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Sample records for hexamethylene diisocyanate exposure

  1. Urine 1,6-Hexamethylene Diamine (HDA) Levels Among Workers Exposed to 1,6-Hexamethylene Diisocyanate (HDI)

    OpenAIRE

    Gaines, Linda G. T.; Fent, Kenneth W.; Flack, Sheila L.; Thomasen, Jennifer M.; Ball, Louise M.; Richardson, David B.; Ding, Kai; Whittaker, Stephen G.; Nylander-french, Leena A.

    2010-01-01

    Urinary 1,6-hexamethylene diamine (HDA) may serve as a biomarker for systemic exposure to 1,6-hexamethylene diisocyanate (HDI) in occupationally exposed populations. However, the quantitative relationships between dermal and inhalation exposure to HDI and urine HDA levels have not been established. We measured acid-hydrolyzed urine HDA levels along with dermal and breathing-zone levels of HDI in 48 automotive spray painters. These measurements were conducted over the course of an entire workd...

  2. Hemoglobin adducts in workers exposed to 1,6-hexamethylene diisocyanate.

    Science.gov (United States)

    Flack, Sheila L; Fent, Kenneth W; Gaines, Linda G T; Thomasen, Jennifer M; Whittaker, Stephen G; Ball, Louise M; Nylander-French, Leena A

    2011-05-01

    We investigated the utility of 1,6-hexamethylene diamine (HDA) hemoglobin adducts as biomarkers of exposure to 1,6-hexamethylene diisocyanate (HDI) monomer. Blood samples from 15 spray painters applying HDI-containing paint were analyzed for hemoglobin HDA (HDA-Hb) and N-acetyl-1,6-hexamethylene diamine (monoacetyl-HDA-Hb) by GC-MS. HDA-Hb was detected in the majority of workers (≤1.2-37 ng/g Hb), whereas monoacetyl-HDA-Hb was detected in one worker (0.06 ng/g Hb). The stronger, positive association between HDA-Hb and cumulative HDI exposure (r(2) = 0.3, p HDA-Hb adducts. This association demonstrates the suitability of HDA-Hb adducts for further validation as a biomarker of HDI exposure.

  3. Effect of 1,6-hexamethylene diisocyanate exposure on peak flowmetry in automobile paint shop workers in Iran.

    Science.gov (United States)

    Pourabedian, Siyamak; Barkhordari, Abdullah; Habibi, Ehsanallah; Rismanchiyan, Masoud; Zare, Mohsen

    2010-06-01

    The aim of this study was to investigate the effects of occupational exposure to 1,6-hexamethylene diisocyanate (HDI) on peak flowmetry in automobile body paint shop workers in Iran. We studied a population of 43 car painters exposed to HDI at their workplaces. Peak expiratory flow was tested for one working week, from the start to the end of each shift. Air was sampled and HDI analysed in parallel, according to the OSHA 42 method. Daily and weekly HDI exposure averages were (0.42+/-0.1) mg m(-3) and (0.13+/-0.05) mg m(-3), respectively. On painting days, 72 % of workers showed more than a 10 % variation in peak expiratory flow. Inhalation exposure exceeded the threshold limit value (TLV) ten times over. This strongly suggests that HDI affected the peak flowmetry in the studied workers.

  4. Gene expression profiling in mouse lung following polymeric hexamethylene diisocyanate exposure

    International Nuclear Information System (INIS)

    Lee, C.-T.; Ylostalo, Joni; Friedman, Mitchell; Hoyle, Gary W.

    2005-01-01

    Isocyanates are a common cause of occupational lung disease. Hexamethylene diisocyanate (HDI), a component of polyurethane spray paints, can induce respiratory symptoms, inflammation, lung function impairment, and isocyanate asthma. The predominant form of HDI in polyurethane paints is a nonvolatile polyisocyanate known as HDI biuret trimer (HDI-BT). Exposure of mice to aerosolized HDI-BT results in pathological effects, including pulmonary edema, lung inflammation, cellular proliferation, and fibrotic lesions, which occur with distinct time courses following exposure. To identify genes that mediate lung pathology in the distinct temporal phases after exposure, gene expression profiles in HDI-BT-exposed C57BL/6J mouse lungs were analyzed. RNase protection assay (RPA) of genes involved in apoptosis, cell survival, and inflammation revealed increased expression of IκBα, Fas, Bcl-X L , TNFα, KC, MIP-2, IL-6, and GM-CSF following HDI-BT exposure. Microarray analysis of approximately 10 000 genes was performed on lung RNA collected from mice 6, 18, and 90 h after HDI-BT exposure and from unexposed mice. Classes of genes whose expression was increased 6 h after exposure included those involved in stress responses (particularly oxidative stress and thiol redox balance), growth arrest, apoptosis, signal transduction, and inflammation. Types of genes whose expression was increased at 18 h included proteinases, anti-proteinases, cytoskeletal molecules, and inflammatory mediators. Transcripts increased at 90 h included extracellular matrix components, transcription factors, inflammatory mediators, and cell cycle regulators. This characterization of the gene expression profile in lungs exposed to HDI-BT will provide a basis for investigating injury and repair pathways that are operative during isocyanate-induced lung disease

  5. Characterization of polyurethane based on polyol synthesized from glycerol and hexamethylene diisocyanate

    International Nuclear Information System (INIS)

    Carvalho, Sabrina M.; Weber, Vanessa; Silva, Tailu N.; Barreto, Pedro L.M.

    2009-01-01

    A new polyol based on glycerol was synthesized and used in the production of polyurethane by reaction with hexamethylene diisocyanate. The polyol was characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform-infrared spectroscopy (FTIR). The polyurethane produced was characterized by FTIR, thermogravimetry (TG), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The polyol was shown to be reactive with hexamethylene diisocyanate, as the FTIR spectrum showed no free isocyanate groups and identified the presence of group -C=O of urethane groups. Analysis by DSC showed that the sample of polyurethane has a glass transition temperature around -8.53 deg C and SEM micrographs showed fracture and surface continuous and not broken. The thermogravimetric analysis showed that the polyurethane produced has a high thermal stability with a temperature of maximum degradation around 430 deg C. (author)

  6. Urine 1,6-hexamethylene diamine (HDA) levels among workers exposed to 1,6-hexamethylene diisocyanate (HDI).

    Science.gov (United States)

    Gaines, Linda G T; Fent, Kenneth W; Flack, Sheila L; Thomasen, Jennifer M; Ball, Louise M; Richardson, David B; Ding, Kai; Whittaker, Stephen G; Nylander-French, Leena A

    2010-08-01

    Urinary 1,6-hexamethylene diamine (HDA) may serve as a biomarker for systemic exposure to 1,6-hexamethylene diisocyanate (HDI) in occupationally exposed populations. However, the quantitative relationships between dermal and inhalation exposure to HDI and urine HDA levels have not been established. We measured acid-hydrolyzed urine HDA levels along with dermal and breathing-zone levels of HDI in 48 automotive spray painters. These measurements were conducted over the course of an entire workday for up to three separate workdays that were spaced approximately 1 month apart. One urine sample was collected before the start of work with HDI-containing paints and subsequent samples were collected during the workday. HDA levels varied throughout the day and ranged from nondetectable to 65.9 microg l(-1) with a geometric mean and geometric standard deviation of 0.10 microg l(-1) +/- 6.68. Dermal exposure and inhalation exposure levels, adjusted for the type of respirator worn, were both significant predictors of urine HDA levels in the linear mixed models. Creatinine was a significant covariate when used as an independent variable along with dermal and respirator-adjusted inhalation exposure. Consequently, exposure assessment models must account for the water content of a urine sample. These findings indicate that HDA exhibits a biphasic elimination pattern, with a half-life of 2.9 h for the fast elimination phase. Our results also indicate that urine HDA level is significantly associated with systemic HDI exposure through both the skin and the lungs. We conclude that urinary HDA may be used as a biomarker of exposure to HDI, but biological monitoring should be tailored to reliably capture the intermittent exposure pattern typical in this industry.

  7. Factors affecting variability in the urinary biomarker 1,6-hexamethylene diamine in workers exposed to 1,6-hexamethylene diisocyanate.

    Science.gov (United States)

    Gaines, Linda G T; Fent, Kenneth W; Flack, Sheila L; Thomasen, Jennifer M; Whittaker, Stephen G; Nylander-French, Leena A

    2011-01-01

    Although urinary 1,6-hexamethylene diamine (HDA) is a useful biomarker of exposure to 1,6-hexamethylene diisocyanate (HDI), a large degree of unexplained intra- and inter-individual variability exists between estimated HDI exposure and urine HDA levels. We investigated the effect of individual and workplace factors on urine HDA levels using quantitative dermal and inhalation exposure data derived from a survey of automotive spray painters exposed to HDI. Painters' dermal and breathing-zone HDI-exposures were monitored over an entire workday for up to three separate workdays, spaced approximately one month apart. One urine sample was collected before the start of work with HDI-containing paints, and multiple samples were collected throughout the workday. Using mixed effects multiple linear regression modeling, coverall use resulted in significantly lower HDA levels (p = 0.12), and weekday contributed to significant variability in HDA levels (p = 0.056). We also investigated differences in urine HDA levels stratified by dichotomous and classification covariates using analysis of variance. Use of coveralls (p = 0.05), respirator type worn (p = 0.06), smoker status (p = 0.12), paint-booth type (p = 0.02), and more than one painter at the shop (p = 0.10) were all found to significantly affect urine HDA levels adjusted for creatinine concentration. Coverall use remained significant (p = 0.10), even after adjusting for respirator type. These results indicate that the variation in urine HDA level is mainly due to workplace factors and that appropriate dermal and inhalation protection is required to prevent HDI exposure.

  8. Single-tracer technique to evaluate pulmonary edema and its application to detect the effect of hexamethylene diisocyanate trimer aerosol exposures

    International Nuclear Information System (INIS)

    Valentini, J.E.; Wong, K.L.; Alarie, Y.

    1983-01-01

    Two hours after a four-hour exposure to hexamethylene diisocyanate trimer (HDIt) aerosol between 2.5 and 39 mg/m3, mice were injected iv with 51 Cr-EDTA (chromium ethylenediaminetetraacetate). Ten minutes later the lung was lavaged. A larger amount of 51 Cr-EDTA was detected in the lung lavage of HDIt mice than of controls in a concentration-related fashion. The concentration-response curve was shifted to the left compared with that constructed using lung weight increase as response. Kinetic studies of the plasma level of 51 Cr-EDTA revealed a three-exponential profile in normal mice, and similar plasma levels were obtained with mice exposed to 18-24 mg/m3 HDIt. However, both the amount of 51 Cr-EDTA in the alveolar space and concentration in the pulmonary extravascular compartment were higher in HDIt-exposed mice than in controls. The data of 51 Cr-EDTA distribution in the lung were fitted with a three-compartment model. According to the model, HDIt exposures increase the permeability constants of 51 Cr-EDTA transport into the alveolar space from blood which accounts for the larger amount of 51 Cr-EDTA in lung lavage of HDIt-exposed mice. This 51 Cr-EDTA injection and lung lavage technique is a sensitive method for detecting pulmonary edema

  9. Neuronal modulation of lung injury induced by polymeric hexamethylene diisocyanate in mice

    International Nuclear Information System (INIS)

    Lee, C.-T.; Poovey, Halet G.; Rando, Roy J.; Hoyle, Gary W.

    2007-01-01

    1,6-Hexamethylene diisocyanate biuret trimer (HDI-BT) is a nonvolatile isocyanate that is a component of polyurethane spray paints. HDI-BT is a potent irritant that when inhaled stimulates sensory nerves of the respiratory tract. The role of sensory nerves in modulating lung injury following inhalation of HDI-BT was assessed in genetically manipulated mice with altered innervation of the lung. Knockout mice with a mutation in the low-affinity nerve growth factor receptor (NGFR), which have decreased innervation by nociceptive nerve fibers, and transgenic mice expressing nerve growth factor (NGF) from the lung-specific Clara cell secretory protein (CCSP) promoter, which have increased innervation of the airways, were exposed to HDI-BT aerosol and evaluated at various times after exposure. NGFR knockout mice exhibited significantly more, and CCSP-NGF transgenic mice exhibited significantly less injury and inflammation compared with wild-type mice, indicative of a protective effect of nociceptive nerves on the lung following HDI-BT inhalation. Transgenic mice overexpressing the tachykinin 1 receptor (Tacr1) in lung epithelial cells also showed less severe injury and inflammation compared with wild-type mice after HDI-BT exposure, establishing a role for released tachykinins acting through Tacr1 in mediating at least part of the protective effect. Treatment of lung fragments from Tacr1 transgenic mice with the Tacr1 ligand substance P resulted in increased cAMP accumulation, suggesting this compound as a possible signaling mediator of protective effects on the lung following nociceptive nerve stimulation. The results indicate that sensory nerves acting through Tacr1 can exert protective or anti-inflammatory effects in the lung following isocyanate exposure

  10. Field Evaluation of Solvent-Free Sampling with Di-n-butylamine for the Determination of Airborne Monomeric and Oligomeric 1,6-Hexamethylene Diisocyanate

    Science.gov (United States)

    2014-03-27

    ISO Guide 34:2009 and ISO / IEC 17025 :2005) for HDI oligomers. Per the manufacturer, a single ASSETTM sampler may be used for over 8 hours which leads...hexamethylene diisocyanate (HDI). During this study, the Supelco ASSETTM EZ4-NCO Dry Sampler was compared to the Omega Specialty Instrument Company ISO ...detection (HPLC-MS); 2) do ASSETTM and ISO -CHEK® samplers collect equivalent HDI monomer and oligomer concentrations; and 3) what is the relative cost of

  11. ASSESSMENT OF HUMAN EXPOSURE TO TOLUENE DIISOCYANATE

    Directory of Open Access Journals (Sweden)

    OLIVIA ANCA RUSU

    2011-03-01

    Full Text Available Assessment of human exposure to toluene diisocyanate. Toluene diisocyanate (TDI, an aromatic compound, may be dangerous for human health. Diisocyanates have wide industrial use in the fabrication of flexible and rigid foams, fibers, elastomers, and coatings such as paints and varnishes. Isocyanates are known skin and respiratory sensitizers, and proper engineering controls should be in place to prevent exposure to isocyanate liquid and vapor; exposure to TDI vapors is well documented to increase asthma risk. The study focused on the exposure of workers and nearby populations to toluene diisocyanate in a Polyurethane Foam Factory located in Baia Mare, Romania. Workplace air measurements were performed in different departments of the plant, after sampling either in fixed points or as personal monitoring. Sampling in four different locations of Baia Mare town was carried out, - during and after the foaming process. TDI sampling was performed on silica cartridge followed by GC-MS analysis. TDI concentration at workplace was lower than 0,035 mg/m³, which represents the permissible exposure limit, while in the city the TDI concentration had shown values below 0,20 μg/m³. Health assessment of a group of 49 workers was based on questionnaire interview, determination of TDI antibodies and lung function tests. Data collected until this stage do not show any negative effects of TDI on the employees health. Since this plant had only recently begun operating, continuous workplace and ambient air TDI monitoring, along with workers health surveillance, is deemed necessary.

  12. Dermal, inhalation, and internal exposure to 1,6-HDI and its oligomers in car body repair shop workers and industrial spray painters

    NARCIS (Netherlands)

    Pronk, A.; Yu, F.; Vlaanderen, J.; Tielemans, E.; Preller, L.; Bobeldijk, I.; Deddens, J.A.; Latza, U.; Baur, X.; Heederik, D.

    2006-01-01

    Objectives: To study inhalation and dermal exposure to hexamethylene diisocyanate (HDI) and its oligomers as well as personal protection equipment (PPE) use during task performance in conjunction with urinary hexamethylene diamine (HDA) in car body repair shop workers and industrial spray painters.

  13. Sub-acute occupational hypersensitivity pneumonitis due to low-level exposure to diisocyanates in a secretary.

    Science.gov (United States)

    Schreiber, J; Knolle, J; Sennekamp, J; Schulz, K T; Hahn, J U; Hering, K G; Raulf-Heimsoth, M; Merget, R

    2008-09-01

    There is virtually no information in the literature about the exposure levels needed to induce hypersensitivity pneumonitis (HP) by diisocyanates. The present study reports a case of occupational HP due to diisocyanates after low-level exposure. A 53-yr-old female never-smoker developed progressive shortness of breath on exertion, cough, fatigue and flu-like symptoms shortly after she began work as a secretary of a car body repair shop. A diagnosis of HP was made 2 yrs later, based on a restrictive ventilatory defect, a reticulonodular and discrete ground-glass pattern on high-resolution computed tomography, lymphocytosis in bronchoalveolar lavage and specific immunoglobulin G antibodies to diisocyanate human serum albumin conjugates in the patient's serum. The diagnosis was confirmed by recovery after exposure cessation and deterioration after re-exposure. Ambient monitoring revealed air concentrations of different diisocyanate monomers below the detection limit in both the patient's work station and in front of the paint spray booths, with the exception of one measurement that showed 4,4-methylenediphenyl diisocyanate concentrations of 3 microg x m(-3) in front of one booth (corresponding to a total reactive isocyanate group concentration of 1 microg x m(-3)). The present authors conclude that concentrations of diisocyanates far below current exposure limits may induce hypersensitivity pneumonitis in susceptible subjects.

  14. Occupational Exposure to HDI: Progress and Challenges in Biomarker Analysis

    OpenAIRE

    Flack, Sheila L.; Ball, Louise M.; Nylander-French, Leena A.

    2010-01-01

    1,6-hexamethylene diisocyanate (HDI) is extensively used in the automotive repair industry and is a commonly reported cause of occupational asthma in industrialized populations. However, the exact pathological mechanism remains uncertain. Characterization and quantification of biomarkers resulting from HDI exposure can fill important knowledge gaps between exposure, susceptibility, and the rise of immunological reactions and sensitization leading to asthma. Here, we discuss existing challenge...

  15. Occupational exposure to diisocyanates in polyurethane foam factory workers

    Directory of Open Access Journals (Sweden)

    Dominika Świerczyńska-Machura

    2015-12-01

    Full Text Available Objectives: The aim of the study was to evaluate health effects of occupational exposure to diisocyanates (DIC among polyurethane foam products factory workers. Material and Methods: Thirty workers had a physical examination, skin prick tests with common allergens, allergen-specific immunoglobulin E (IgE antibodies to diisocyanates and pulmonary function tests. Concentrations of selected isocyanates in the workplace air samples as well as concentration of their metabolites in the urine samples collected from the workers of the plant were determined. Results: The most frequent work-related symptoms reported by the examined subjects were rhinitis and skin symptoms. Sensitization to at least 1 common allergen was noted in 26.7% of the subjects. Spirometry changes of bronchial obstruction of a mild degree was observed in 5 workers. The specific IgE antibodies to toluene diisocyanate (TDI and 4,4’-methylenebis(phenyl isocyanate (MDI were not detected in any of the patients’ serum. Cellular profiles of the collected induced sputum (ISP did not reveal any abnormalities. Air concentrations of TDI isomers ranged 0.2–58.9 μg/m3 and in 7 cases they exceeded the Combined Exposure Index (CEI value for those compounds. Concentrations of TDI metabolites in post-shift urine samples were significantly higher than in the case of pre-shift urine samples and in 6 cases they exceeded the British Biological Monitoring Guidance Value (BMGV – 1 μmol amine/mol creatinine. We didn’t find a correlation between urinary concentrations of TDI, concentrations in the air and concentrations of toluenediamine (TDA in the post shift urine samples. Lack of such a correlation may be an effect of the respiratory protective equipment use. Conclusions: Determination of specific IgE in serum is not sensitive enough to serve as a biomarker. Estimation of concentrations of diisocyanate metabolites in urine samples and the presence of work-related allergic symptoms seem to be

  16. Quantitative plasma biomarker analysis in HDI exposure assessment.

    Science.gov (United States)

    Flack, Sheila L; Fent, Kenneth W; Trelles Gaines, Linda G; Thomasen, Jennifer M; Whittaker, Steve; Ball, Louise M; Nylander-French, Leena A

    2010-01-01

    Quantification of amines in biological samples is important for evaluating occupational exposure to diisocyanates. In this study, we describe the quantification of 1,6-hexamethylene diamine (HDA) levels in hydrolyzed plasma of 46 spray painters applying 1,6-hexamethylene diisocyanate (HDI)-containing paint in vehicle repair shops collected during repeated visits to their workplace and their relationship with dermal and inhalation exposure to HDI monomer. HDA was detected in 76% of plasma samples, as heptafluorobutyryl derivatives, and the range of HDA concentrations was HDA levels and HDI inhalation exposure measured on the same workday was low (N = 108, r = 0.22, P = 0.026) compared with the correlation between plasma HDA levels and inhalation exposure occurring approximately 20 to 60 days before blood collection (N = 29, r = 0.57, P = 0.0014). The correlation between plasma HDA levels and HDI dermal exposure measured on the same workday, although statistically significant, was low (N = 108, r = 0.22, P = 0.040) while the correlation between HDA and dermal exposure occurring approximately 20 to 60 days before blood collection was slightly improved (N = 29, r = 0.36, P = 0.053). We evaluated various workplace factors and controls (i.e. location, personal protective equipment use and paint booth type) as modifiers of plasma HDA levels. Workers using a downdraft-ventilated booth had significantly lower plasma HDA levels relative to semi-downdraft and crossdraft booth types (P = 0.0108); this trend was comparable to HDI inhalation and dermal exposure levels stratified by booth type. These findings indicate that HDA concentration in hydrolyzed plasma may be used as a biomarker of cumulative inhalation and dermal exposure to HDI and for investigating the effectiveness of exposure controls in the workplace.

  17. Diisocyanate emission from a paint product: a preliminary analysis.

    Science.gov (United States)

    Jarand, Curtis W; Akapo, Samuel O; Swenson, Lonie J; Kelman, Bruce J

    2002-07-01

    Exposure of workers to diisocyanates in the polyurethane foam manufacturing industry is well documented. However, very little quantitative data have been published on exposure to diisocyanates from the use of paints and coatings. The purpose of this study was to evaluate emission of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate (2,6-TDI), and isophorone diisocyanate from a commercially available two-stage concrete coating and sealant. A laboratory model of an outdoor deck coating process was developed and diisocyanate concentrations determined by derivatization with 1-(2-methoxyphenol)-piperazine and subsequent high performance liquid chromatographic analysis with UV detection. The detection limit for 2,4-toluene diisocyanate and 2,6-toluene diisocyanate urea derivatives was 0.6 microg TDI/gm wet product, and 0.54 microg IPDI/gm wet product for the isophorone diisocyanate urea derivative. No 2,4-toluene diisocyanate or isophorone diisocyanate was detected in the mixed product. A maximum mean 2,6-TDI emission rate of 0.32 microg of 2,6-TDI/gram of wet product applied/hour was observed for the 1-hour sampling time, 0.38 microg of 2,6-TDI/gram of wet product applied/hour was observed for the 5-hour sampling time, and 0.02 micrpg of 2,6-TDI/gram of wet product applied/hour was observed for the 15-hour sampling time. The decrease in rate of 2,6-TDI emission over the 15-hour period indicates that emission of 2,6-TDI is virtually complete after 5 hours. These emission rates should allow industrial hygienists to calculate exposures to isocyanates emitted from at least one curing sealant.

  18. Phosgene-free synthesis of hexamethylene-1,6-diisocyanate by the catalytic decomposition of dimethylhexane-1,6-dicarbamate over zinc-incorporated berlinite (ZnAlPO{sub 4})

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Da-Lei [Department of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Luo, Jun-Yin; Wen, Ru-Yu [Department of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006 (China); Deng, Jian-Ru [College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Chao, Zi-Sheng, E-mail: zschao@yahoo.com [College of Chemistry and Chemical Engineering, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2014-02-15

    Highlights: • Synthesis of HDI via HDU decomposition over ZnAlPO{sub 4} heterogeneous catalyst. • Employment of self-designed reliable fixed bed reactor for HDU decomposition to HDI. • As high as 89.4% yield of HDI over ZnAlPO{sub 4} catalyst. • High stability and large ability for repeating usage of ZnAlPO{sub 4} catalyst. -- Abstract: The phosgene-free synthesis of hexamethylene-1,6-diisocyanate (HDI) by the decomposition of dimethylhexane-1,6-dicarbamate (HDU) was carried out on a self-designed fixed-bed catalytic reactor, using zinc-incorporated berlinite (ZnAlPO{sub 4}) as catalyst, dioctyl phthalate (DOP) as solvent and N{sub 2} as carrier gas. Factors influencing the yield of HDI, including the Zn/Al molar ratio, HDU concentration and liquid space velocity (LHSV), were investigated. Under the optimized reaction conditions, i.e., 4.8 wt.% concentration of HDU in DOP, 100 ml/min N{sub 2} flow rate, 0.09 MPa vacuum, 623 K reaction temperature, 1.2 h{sup −1} LHSV and catalyst usage 2.0 g, a 89.4% yield of HDI had been achieved over the ZnAlPO{sub 4} (molar ratio Zn/Al = 0.04) catalyst. The ZnAlPO{sub 4} catalyst was found to exhibit a considerable large on-stream stability and could be repeatedly used in the decomposition of HDU to HDI, after its regeneration.

  19. Occupational exposure to HDI: progress and challenges in biomarker analysis.

    Science.gov (United States)

    Flack, Sheila L; Ball, Louise M; Nylander-French, Leena A

    2010-10-01

    1,6-Hexamethylene diisocyanate (HDI) is extensively used in the automotive repair industry and is a commonly reported cause of occupational asthma in industrialized populations. However, the exact pathological mechanism remains uncertain. Characterization and quantification of biomarkers resulting from HDI exposure can fill important knowledge gaps between exposure, susceptibility, and the rise of immunological reactions and sensitization leading to asthma. Here, we discuss existing challenges in HDI biomarker analysis including the quantification of N-acetyl-1,6-hexamethylene diamine (monoacetyl-HDA) and N,N'-diacetyl-1,6-hexamethylene diamine (diacetyl-HDA) in urine samples based on previously established methods for HDA analysis. In addition, we describe the optimization of reaction conditions for the synthesis of monoacetyl-HDA and diacetyl-HDA, and utilize these standards for the quantification of these metabolites in the urine of three occupationally exposed workers. Diacetyl-HDA was present in untreated urine at 0.015-0.060 μg/l. Using base hydrolysis, the concentration range of monoacetyl-HDA in urine was 0.19-2.2 μg/l, 60-fold higher than in the untreated samples on average. HDA was detected only in one sample after base hydrolysis (0.026 μg/l). In contrast, acid hydrolysis yielded HDA concentrations ranging from 0.36 to 10.1 μg/l in these three samples. These findings demonstrate HDI metabolism via N-acetylation metabolic pathway and protein adduct formation resulting from occupational exposure to HDI. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Indoor air pollution evaluation with emphasize on HDI and biological assessment of HDA in the polyurethane factories.

    Science.gov (United States)

    Mirmohammadi, Mirtaghi; Hakimi Ibrahim, M; Ahmad, Anees; Kadir, Mohd Omar Abdul; Mohammadyan, M; Mirashrafi, S B

    2010-06-01

    Today, many raw materials used in factories may have a dangerous effect on the physiological system of workers. One of them which is widely used in the polyurethane factories is diisocyanates. These compounds are widely used in surface coatings, polyurethane foams, adhesives, resins, elastomers, binders, and sealants. Exposure to diisocyanates causes irritation to the skin, mucous membranes, eyes, and respiratory tract. Hexamethylene diamine (HDA) is metabolite of hexamethylene diisocyanate (HDI). It is an excretory material by worker's urine who is exposed to HDI. Around 100 air samples were collected from five defined factories by midget impinger which contained dimethyl sulfoxide absorbent as a solvent and tryptamine as reagent. Samples were analyzed by high-performance liquid chromatography with EC\\UV detector using NIOSH 5522 method of sampling. Also, 50 urine samples collected from workers were also analyzed using William's biological analysis method. The concentration of HDI into all air samples were more than 88 microg/m(3), and they have shown high concentration of pollutant in the workplaces in comparison with NIOSH standard, and all of the workers' urine were contaminated by HDA. The correlation and regression test were used to obtain statistical model for HDI and HDA, which is useful for the prediction of diisocyanates pollution situation in the polyurethane factories.

  1. Evaluation of level of impregnation monomers in hydrotalcite; Avaliacao do grau de impregnacao de monomeros em hidrotalcita

    Energy Technology Data Exchange (ETDEWEB)

    Carmo, Danieli M. do, E-mail: danielimcarmo@hotmail.com [Instituto de Macromoleculas Professora Eloisa Mano - IMA, Universidade Federal do Rio de Janeiro - UFRJ, RJ (Brazil); Machado, Jacson S.C.; Oliveira, Marcelo F.L.; Oliveira, Marcia G. [Instituto Nacional de Tecnologia - INT, Rio de Janeiro, RJ (Brazil); Soares, Bluma G. [Instituto de Macromoleculas Professora Eloisa Mano - IMA, Universidade Federal do Rio de Janeiro - UFRJ, RJ (Brazil)

    2011-07-01

    To evaluate the impregnation degree of 1,6-hexamethylene diisocyanate and 1,4-butanediol monomers in hydrotalcite clays it was prepared dispersions with mixing ratio 1:100 (clay/monomer), using the Ultraturrax and Ultrasound. Subsequently the samples were characterized by Fourier Transform Infrared Spectroscopy and X-ray Diffraction. Swelling tests and Tyndall effect were used to illustrate the different dispersions. The results indicated a strong interaction between the hydrotalcite with 1,6-hexamethylene diisocyanate, favoring the formation of intercalated structures. (author)

  2. Evaluation of level of impregnation monomers in hydrotalcite

    International Nuclear Information System (INIS)

    Carmo, Danieli M. do; Machado, Jacson S.C.; Oliveira, Marcelo F.L.; Oliveira, Marcia G.; Soares, Bluma G.

    2011-01-01

    To evaluate the impregnation degree of 1,6-hexamethylene diisocyanate and 1,4-butanediol monomers in hydrotalcite clays it was prepared dispersions with mixing ratio 1:100 (clay/monomer), using the Ultraturrax and Ultrasound. Subsequently the samples were characterized by Fourier Transform Infrared Spectroscopy and X-ray Diffraction. Swelling tests and Tyndall effect were used to illustrate the different dispersions. The results indicated a strong interaction between the hydrotalcite with 1,6-hexamethylene diisocyanate, favoring the formation of intercalated structures. (author)

  3. Isocyanate test antigens

    International Nuclear Information System (INIS)

    Karol, M.H.; Alarie, Y.C.

    1980-01-01

    A test antigen for detecting antibodies to a diisocyanate comprises the reaction product of a protein and a monoisocyanate derived from the same radical as the diisocyanate. The diisocyanates most usually encountered and therefore calling for antibody detection are those of toluene, hexamethylene, methylene, isophorone and naphthylene. The preferred protein is human serum albumin. (author)

  4. Degradation Studies of β-Cyclodextrin Polyurethane Polymers using

    African Journals Online (AJOL)

    diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) were carried out by exposing the polymers to different soil types for up to 120 days. The aim of the study was to determine the fate of these novel polymers in the environment.

  5. 78 FR 37818 - Request for Information on Toluene Diisocyanates

    Science.gov (United States)

    2013-06-24

    ...) information on possible health effects observed in workers exposed to toluene diisocyanate, including exposure... information demonstrating potential health effects in workers exposed to TDI. (6) Research findings from in... DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention [CDC-2013-0011...

  6. Polyurethanes elastomers with amide chain extenders of uniform length

    NARCIS (Netherlands)

    van der Schuur, J.M.; Noordover, B.A.J.; Noordover, Bart; Gaymans, R.J.

    2006-01-01

    Toluene diisocyanate based polyurethanes with amide extenders were synthesized poly(propylene oxide) with a number average molecular weight of 2000 and endcapped with toluene diisocyanate was used as the polyether segment. The chain extenders were based on poly(hexamethylene terephthalamide):

  7. Polyuretehane elastomers with amide chain extenders of uniform length

    NARCIS (Netherlands)

    Schuur, van der M.; Noordover, B.A.J.; Gaymans, R.J.

    2006-01-01

    Toluene diisocyanate based polyurethanes with amide extenders were synthesized poly(propylene oxide) with a number average molecular weight of 2000 and endcapped with toluene diisocyanate was used as the polyether segment. The chain extenders were based on poly(hexamethylene terephthalamide):

  8. Isocyanate exposure and asthma in the UK vehicle repair industry.

    Science.gov (United States)

    Stocks, S J; Jones, K; Piney, M; Agius, R M

    2015-12-01

    Organic diisocyanates are a common cause of occupational asthma, particularly in motor vehicle repair (MVR) workers. The UK Health & Safety Laboratory provides screening for urinary hexamethylenediamine (UHDA), a biomarker of exposure to 1,6-hexamethylene diisocyanate (HDI). The UK Surveillance of Work-related and Occupational Respiratory Disease scheme (SWORD) has collected reports of occupational asthma since 1996. To compare trends in HDI exposure with trends in the incidence of work-related asthma attributed to isocyanates or paint spraying in MVR workers reported to SWORD. Two-level regression models were used to estimate trends in UHDA levels and work-related asthma in MVR workers reported to SWORD. The direction and magnitude of the trends were compared descriptively. From 2006 to 2014, there was a significant decline in the number of urine samples with detectable levels of UHDA (odds ratio = 0.96; 95% confidence intervals 0.94-0.98) and minimal change in those over the guidance value (1.03; 1.00-1.06). Over the same period, there was a significant decline in all asthma cases attributed to isocyanates or paint spraying reported to SWORD (0.90; 0.86-0.94) and a non-significant decline among MVR workers (0.94; 0.86-1.02). The simultaneous decrease in HDI exposure and incident cases of asthma reported to SWORD is temporally consistent with a reduction in exposure to airborne isocyanate leading to a reduction in asthma. Although this is not direct evidence of a causal relationship between the two trends, it is suggestive. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine.

  9. Evaluation of workers' exposure to methylene diphenyl diisocyanate (MDI) in an automobile manufacturing company, Iran.

    Science.gov (United States)

    Kakooei, Hossein; Shahtaheri, Seyed Jamaleddin; Karbasi, Hossein-Ali

    2006-01-01

    Evaluation of personal inhalation exposure to methylene diphenyl diisocyanate (MDI) among 39 employees, working in the window fixation and window glue processes in an automobile manufacturing company was performed. This study was conducted for both case and control groups. After sampling and sample preparation processes, MDI was determined with a UV-VIS spectrophotometer at 590 nm; the lung function was assessed with a digital spirometer, too. The average concentration of MDI in the window fixation, and window glue workplaces were 34.53 and 27.37 micro g/m3, respectively, which was lower than the threshold limit value (TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) (51 micro g/m3). Respiratory symptoms in the exposed group were significantly different compared to the unexposed group (p < .05). Lung capacities in the case group were lower than in the control group (p < .05). Therefore, MDI can be easily measured making it possible to evaluate the adverse effects caused by occupational exposure.

  10. The respiratory local lymph node assay as a tool to study respiratory sensitizers.

    Science.gov (United States)

    Arts, Josje H E; de Jong, Wim H; van Triel, Jos J; Schijf, Marcel A; de Klerk, Arja; van Loveren, Henk; Kuper, C Frieke

    2008-12-01

    The local lymph node assay (LLNA) is used to test the potential of low molecular weight (LMW) compounds to induce sensitization via the skin. In the present study, a respiratory LLNA was developed. Male BALB/c mice were exposed head/nose-only during three consecutive days for 45, 90, 180, or 360 min/day to various LMW allergens. Ear application (skin LLNA) was used as a positive control. Negative controls were exposed to the vehicle. Three days after the last exposure, proliferation was determined in the draining mandibular lymph nodes, and the respiratory tract was examined microscopically. Upon inhalation, the allergens trimellitic anhydride, phthalic anhydride, hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate (IPDI), dinitrochlorobenzene, and oxazolone were positive and showed stimulation indices (SIs) up to 11, whereas trimeric IPDI, formaldehyde, and methyl salicylate were negative (viz. SI LLNA.

  11. Contact and respiratory sensitizers can be identified by cytokine profiles following inhalation exposure

    International Nuclear Information System (INIS)

    De Jong, Wim H.; Arts, Josje H.E.; De Klerk, Arja; Schijf, Marcel A.; Ezendam, Janine; Kuper, C. Frieke; Van Loveren, Henk

    2009-01-01

    There are currently no validated animal models that can identify low molecular weight (LMW) respiratory sensitizers. The Local Lymph Node Assay (LLNA) is a validated animal model developed to detect contact sensitizers using skin exposure, but all LMW respiratory sensitizers tested so far were also positive in this assay. Discrimination between contact and respiratory sensitizers can be achieved by the assessment of cytokine profiles. In a LLNA using the inhalation route, both contact and respiratory sensitizers enhanced proliferation in the draining lymph nodes. The question was if their cytokine profiles were affected by the route of exposure. Male BALB/c mice were exposed head/nose-only during 3 consecutive days to the respiratory sensitizers trimellitic anhydride, phthalic anhydride, toluene diisocyanate, hexamethylene diisocyanate (HDI), and isophorone diisocyanate; the contact sensitizers dinitrochlorobenzene (DNCB), oxazolone (OXA) and formaldehyde (FA), and the irritant methyl salicylate (MS). Three days after the last exposure the draining lymph nodes were excised and cytokine production was measured after ex vivo stimulation with Concanavalin A. Skin application was used as a positive control. After inhalation exposure the respiratory sensitizers induced more interleukin-4 (IL-4) and interleukin (IL-10) compared to the contact sensitizers, whereas the contact sensitizers, except formaldehyde, induced relatively more interferon-γ (IFN-γ) production. When IL-4 and IFN-γ were plotted as a function of the proliferative response, it was shown that IL-4 could be used to identify respiratory sensitizers, except HDI, at concentration levels inducing intermediate stimulation indices. HDI could be distinguished from DNCB and OXA at high SI values. In contrast, contact sensitizers could only be identified when IFN-γ was measured at high stimulation indices. The skin positive control, tested at high concentrations, showed comparable results for IL-4 and IL-10

  12. Airborne Isocyanate Exposures in the Collision Repair Industry and a Comparison to Occupational Exposure Limits

    Science.gov (United States)

    Reeb-Whitaker, Carolyn; Whittaker, Stephen G.; Ceballos, Diana M.; Weiland, Elisa C.; Flack, Sheila L.; Fent, Kenneth W.; Thomasen, Jennifer M.; Gaines, Linda G. Trelles; Nylander-French, Leena A.

    2014-01-01

    Isocyanate exposure was evaluated in 33 spray painters from 25 Washington State autobody shops. Personal breathing zone samples (n = 228) were analyzed for isophorone diisocyanate (IPDI) monomer, 1,6-hexamethylene diisocyanate (HDI) monomer, IPDI polyisocyanate, and three polyisocyanate forms of HDI. The objective was to describe exposures to isocyanates while spray painting, compare them with short-term exposure limits (STELs), and describe the isocyanate composition in the samples. The composition of polyisocyanates (IPDI and HDI) in the samples varied greatly, with maximum amounts ranging from up to 58% for HDI biuret to 96% for HDI isocyanurate. There was a significant inverse relationship between the percentage composition of HDI isocyanurate to IPDI and to HDI uretdione. Two 15-min STELs were compared: (1) Oregon's Occupational Safety and Health Administration (OR-OSHA) STEL of 1000 μg/m3 for HDI polyisocyanate, and (2) the United Kingdom's Health and Safety Executive (UK-HSE) STEL of 70 μg NCO/m3 for all isocyanates. Eighty percent of samples containing HDI polyisocyanate exceeded the OR-OSHA STEL while 98% of samples exceeded the UKHSE STEL. The majority of painters (67%) wore half-face air-purifying respirators while spray painting. Using the OROSHA and the UK-HSE STELs as benchmarks, 21% and 67% of painters, respectively, had at least one exposure that exceeded the respirator's OSHA-assigned protection factor. A critical review of the STELs revealed the following limitations: (1) the OR-OSHA STEL does not include all polyisocyanates, and (2) the UK-HSE STEL is derived from monomeric isocyanates, whereas the species present in typical spray coatings are polyisocyanates. In conclusion, the variable mixtures of isocyanates used by autobody painters suggest that an occupational exposure limit is required that includes all polyisocyanates. Despite the limitations of the STELs, we determined that a respirator with an assigned protection factor of 25 or

  13. Airborne isocyanate exposures in the collision repair industry and a comparison to occupational exposure limits.

    Science.gov (United States)

    Reeb-Whitaker, Carolyn; Whittaker, Stephen G; Ceballos, Diana M; Weiland, Elisa C; Flack, Sheila L; Fent, Kenneth W; Thomasen, Jennifer M; Trelles Gaines, Linda G; Nylander-French, Leena A

    2012-01-01

    Isocyanate exposure was evaluated in 33 spray painters from 25 Washington State autobody shops. Personal breathing zone samples (n = 228) were analyzed for isophorone diisocyanate (IPDI) monomer, 1,6-hexamethylene diisocyanate (HDI) monomer, IPDI polyisocyanate, and three polyisocyanate forms of HDI. The objective was to describe exposures to isocyanates while spray painting, compare them with short-term exposure limits (STELs), and describe the isocyanate composition in the samples. The composition of polyisocyanates (IPDI and HDI) in the samples varied greatly, with maximum amounts ranging from up to 58% for HDI biuret to 96% for HDI isocyanurate. There was a significant inverse relationship between the percentage composition of HDI isocyanurate to IPDI and to HDI uretdione. Two 15-min STELs were compared: (1) Oregon's Occupational Safety and Health Administration (OR-OSHA) STEL of 1000 μg/m(3) for HDI polyisocyanate, and (2) the United Kingdom's Health and Safety Executive (UK-HSE) STEL of 70 μg NCO/m(3) for all isocyanates. Eighty percent of samples containing HDI polyisocyanate exceeded the OR-OSHA STEL while 98% of samples exceeded the UK-HSE STEL. The majority of painters (67%) wore half-face air-purifying respirators while spray painting. Using the OR-OSHA and the UK-HSE STELs as benchmarks, 21% and 67% of painters, respectively, had at least one exposure that exceeded the respirator's OSHA-assigned protection factor. A critical review of the STELs revealed the following limitations: (1) the OR-OSHA STEL does not include all polyisocyanates, and (2) the UK-HSE STEL is derived from monomeric isocyanates, whereas the species present in typical spray coatings are polyisocyanates. In conclusion, the variable mixtures of isocyanates used by autobody painters suggest that an occupational exposure limit is required that includes all polyisocyanates. Despite the limitations of the STELs, we determined that a respirator with an assigned protection factor of 25 or

  14. Poly(Lactic Acid) Based Flexible Films

    OpenAIRE

    Fathilah binti Ali; Jamarosliza Jamaluddin; Arun Kumar Upadhyay

    2014-01-01

    Poly(lactic acid) (PLA) is a biodegradable polymer which has good mechanical properties, however, its brittleness limits its usage especially in packaging materials. Therefore, in this work, PLA based polyurethane films were prepared by synthesizing with different types of isocyanates; methylene diisocyanate (MDI) and hexamethylene diisocyanates (HDI). For this purpose, PLA based polyurethane must have good strength and flexibility. Therefore, polycaprolactone which has b...

  15. Fate and potential environmental effects of methylenediphenyl diisocyanate and toluene diisocyanate released into the atmosphere.

    Science.gov (United States)

    Tury, Bernard; Pemberton, Denis; Bailey, Robert E

    2003-01-01

    Information from a variety of sources has been collected and summarized to facilitate an overview of the atmospheric fate and potential environmental effects of emissions of methylenediphenyl diisocyanate (MDI) or toluene diisocyanate (TDI) to the atmosphere. Atmospheric emissions of both MDI and TDI are low, both in terms of concentration and mass, because of their low volatility and the need for careful control over all aspects of their lifecycle from manufacture through disposal. Typical emission losses for TDI are 25 g/t of TDI used in slabstock foam production. MDI emission losses are lower, often less than 1 g/t of MDI used. Dispersion modeling predicts that concentrations at the fenceline or beyond are very low for typical releases. Laboratory studies show that TDI (and by analogy MDI) does not react with water in the gas phase at a significant rate. The primary degradation reaction of these aromatic diisocyanates in the atmosphere is expected to be oxidation by OH radicals with an estimated half-life of one day. Laboratory studies also show that this reaction is not expected to result in increased ground-level ozone accumulation.

  16. Atmospheric analyzer, carbon monoxide monitor and toluene diisocyanate monitor

    Science.gov (United States)

    Shannon, A. V.

    1977-01-01

    The purpose of the atmospheric analyzer and the carbon monoxide and toluene diisocyanate monitors is to analyze the atmospheric volatiles and to monitor carbon monoxide and toluene diisocyanate levels in the cabin atmosphere of Skylab. The carbon monoxide monitor was used on Skylab 2, 3, and 4 to detect any carbon monoxide levels above 25 ppm. Air samples were taken once each week. The toluene diisocyanate monitor was used only on Skylab 2. The loss of a micrometeoroid shield following the launch of Skylab 1 resulted in overheating of the interior walls of the Orbital Workshop. A potential hazard existed from outgassing of an isocyanate derivative resulting from heat-decomposition of the rigid polyurethane wall insulation. The toluene diisocyanate monitor was used to detect any polymer decomposition. The atmospheric analyzer was used on Skylab 4 because of a suspected leak in the Skylab cabin. An air sample was taken at the beginning, middle, and the end of the mission.

  17. Dermal, inhalation, and internal exposure to 1,6-HDI and its oligomers in car body repair shop workers and industrial spray painters.

    Science.gov (United States)

    Pronk, A; Yu, F; Vlaanderen, J; Tielemans, E; Preller, L; Bobeldijk, I; Deddens, J A; Latza, U; Baur, X; Heederik, D

    2006-09-01

    To study inhalation and dermal exposure to hexamethylene diisocyanate (HDI) and its oligomers as well as personal protection equipment (PPE) use during task performance in conjunction with urinary hexamethylene diamine (HDA) in car body repair shop workers and industrial spray painters. Personal task based inhalation samples (n = 95) were collected from six car body repair shops and five industrial painting companies using impingers with di-n-butylamine (DBA) in toluene. In parallel, dermal exposure was assessed using nitril rubber gloves. Gloves were submerged into DBA in toluene after sampling. Analysis for HDI and its oligomers was performed by LC-MS/MS. Urine samples were collected from 55 workers (n = 291) and analysed for HDA by GC-MS. Inhalation exposure was strongly associated with tasks during which aerosolisation occurs. Dermal exposure occurred during tasks that involve direct handling of paint. In car body repair shops associations were found between detectable dermal exposure and glove use (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.09 to 0.57) and inhalation exposure level (OR 1.34, 95% CI 0.97 to 1.84 for a 10-fold increase). HDA in urine could be demonstrated in 36% and 10% of car body repair shop workers and industrial painting company workers respectively. In car body repair shops, the frequency of detectable HDA was significantly elevated at the end of the working day (OR 2.13, 95% CI 1.07 to 4.22 for 3-6 pm v 0-8 am). In both branches HDA was detected in urine of approximately 25% of the spray painters. In addition HDA was detected in urine of a large proportion of non-spray painters in car body repair shops. Although (spray) painting with lacquers containing isocyanate hardeners results in the highest external exposures to HDI and oligomers, workers that do not perform paint related tasks may also receive a considerable internal dose.

  18. A study on the grafting reaction of isocyanates with hydroxyapatite particles

    NARCIS (Netherlands)

    Liu, Q.; de Wijn, J.R.; van Blitterswijk, Clemens

    1998-01-01

    The surface grafting reactions of a series of isocyanates with hydroxyapatite particles at different temperatures were studied by Infrared spectrophotometry (IR) and thermal gravimetric analysis (TGA). The study results show that both hexamethylene diisocyanate (HMDI) and isocyanatoethyl

  19. Dermal, inhalation, and internal exposure to 1,6‐HDI and its oligomers in car body repair shop workers and industrial spray painters

    Science.gov (United States)

    Pronk, A; Yu, F; Vlaanderen, J; Tielemans, E; Preller, L; Bobeldijk, I; Deddens, J A; Latza, U; Baur, X; Heederik, D

    2006-01-01

    Objectives To study inhalation and dermal exposure to hexamethylene diisocyanate (HDI) and its oligomers as well as personal protection equipment (PPE) use during task performance in conjunction with urinary hexamethylene diamine (HDA) in car body repair shop workers and industrial spray painters. Methods Personal task based inhalation samples (n = 95) were collected from six car body repair shops and five industrial painting companies using impingers with di‐n‐butylamine (DBA) in toluene. In parallel, dermal exposure was assessed using nitril rubber gloves. Gloves were submerged into DBA in toluene after sampling. Analysis for HDI and its oligomers was performed by LC‐MS/MS. Urine samples were collected from 55 workers (n = 291) and analysed for HDA by GC‐MS. Results Inhalation exposure was strongly associated with tasks during which aerosolisation occurs. Dermal exposure occurred during tasks that involve direct handling of paint. In car body repair shops associations were found between detectable dermal exposure and glove use (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.09 to 0.57) and inhalation exposure level (OR 1.34, 95% CI 0.97 to 1.84 for a 10‐fold increase). HDA in urine could be demonstrated in 36% and 10% of car body repair shop workers and industrial painting company workers respectively. In car body repair shops, the frequency of detectable HDA was significantly elevated at the end of the working day (OR 2.13, 95% CI 1.07 to 4.22 for 3–6 pm v 0–8 am). In both branches HDA was detected in urine of ∼25% of the spray painters. In addition HDA was detected in urine of a large proportion of non‐spray painters in car body repair shops. Conclusion Although (spray) painting with lacquers containing isocyanate hardeners results in the highest external exposures to HDI and oligomers, workers that do not perform paint related tasks may also receive a considerable internal dose. PMID:16728504

  20. Composite biomaterials with chemical bonding between hydroxyapatite filler particles and PEG/PBT copolymer matrix

    NARCIS (Netherlands)

    Liu, Qing; de Wijn, J.R.; van Blitterswijk, Clemens

    1998-01-01

    In an effort to make composites from hydroxyapatite and a PEG/PBT copolymer (PolyactiveTM 70/30), chemical linkages were introduced between the filler particles and polymer matrix using hexamethylene diisocyanate as a coupling agent. Infrared spectra (IR) and thermal gravimetric analysis (TGA)

  1. Synthesis, Characterization and Biocompatibility of Biodegradable Elastomeric Poly(ether-ester urethane)s Based on Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and Poly(ethylene glycol) via Melting Polymerization

    DEFF Research Database (Denmark)

    Li, Zibiao; Yang, Xiaodi; Wu, Linping

    2009-01-01

    Poly(ether-ester urethane)s (PUs) multiblock co-polymers were synthesized from telechelic hydroxylated poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(ethylene glycol) (PEG) via a melting polymerization (MP) process using 1,6-hexamethylene diisocyanate (HDI) as a non-toxic couplin...

  2. Immune sensitization to methylene diphenyl diisocyanate (MDI resulting from skin exposure: albumin as a carrier protein connecting skin exposure to subsequent respiratory responses

    Directory of Open Access Journals (Sweden)

    Redlich Carrie A

    2011-03-01

    Full Text Available Abstract Background Methylene diphenyl diisocyanate (MDI, a reactive chemical used for commercial polyurethane production, is a well-recognized cause of occupational asthma. The major focus of disease prevention efforts to date has been respiratory tract exposure; however, skin exposure may also be an important route for inducing immune sensitization, which may promote subsequent airway inflammatory responses. We developed a murine model to investigate pathogenic mechanisms by which MDI skin exposure might promote subsequent immune responses, including respiratory tract inflammation. Methods Mice exposed via the skin to varying doses (0.1-10% w/v of MDI diluted in acetone/olive oil were subsequently evaluated for MDI immune sensitization. Serum levels of MDI-specific IgG and IgE were measured by enzyme-linked immunosorbant assay (ELISA, while respiratory tract inflammation, induced by intranasal delivery of MDI-mouse albumin conjugates, was evaluated based on bronchoalveolar lavage (BAL. Autologous serum IgG from "skin only" exposed mice was used to detect and guide the purification/identification of skin proteins antigenically modified by MDI exposure in vivo. Results Skin exposure to MDI resulted in specific antibody production and promoted subsequent respiratory tract inflammation in animals challenged intranasally with MDI-mouse albumin conjugates. The degree of (secondary respiratory tract inflammation and eosinophilia depended upon the (primary skin exposure dose, and was maximal in mice exposed to 1% MDI, but paradoxically limited in mice receiving 10-fold higher doses (e.g. 10% MDI. The major antigenically-modified protein at the local MDI skin exposure site was identified as albumin, and demonstrated biophysical changes consistent with MDI conjugation. Conclusions MDI skin exposure can induce MDI-specific immune sensitivity and promote subsequent respiratory tract inflammatory responses and thus, may play an important role in MDI asthma

  3. Process for the encapsulation of radioactive wastes

    International Nuclear Information System (INIS)

    Pordes, O.; Plows, J.P.; Hill, M.L.

    1980-01-01

    Radioactive waste material, particularly radioactive ion exchange resin in the wet condition, is encapsulated in a polyurethane by dispersing the waste in an aqueous emulsion of an organic polyol, a polyisocyanate and an hydraulic cement and allowing the emulsion to set to form a monolithic block. If desired the emulsion may also contain additional filler e.g. sand or aggregate to increase the density of the final product. Preferred polyurethanes are those made from a polyester polyol and an organic diisocyanate, particularly hexamethylene diisocyanate. (author)

  4. Toluene diisocyanate: Induction of the autotaxin-lysophosphatidic acid axis and its association with airways symptoms

    Energy Technology Data Exchange (ETDEWEB)

    Broström, Julia M. [Division of Occupational and Environmental Medicine, Lund University, SE 221 85 Lund (Sweden); Ye, Zhi-wei [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE 171 77 Stockholm (Sweden); Axmon, Anna; Littorin, Margareta; Tinnerberg, Håkan; Lindh, Christian H. [Division of Occupational and Environmental Medicine, Lund University, SE 221 85 Lund (Sweden); Zheng, Huiyuan; Ghalali, Aram; Stenius, Ulla [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE 171 77 Stockholm (Sweden); Jönsson, Bo A.G. [Division of Occupational and Environmental Medicine, Lund University, SE 221 85 Lund (Sweden); Högberg, Johan, E-mail: johan.hogberg@ki.se [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE 171 77 Stockholm (Sweden)

    2015-09-15

    Diisocyanates are industrial chemicals which have a wide range of applications in developed and developing countries. They are notorious lung toxicants and respiratory sensitizers. However, the mechanisms behind their adverse effects are not adequately characterized. Autotaxin (ATX) is an enzyme producing lysophosphatidic acid (LPA), and the ATX-LPA axis has been implicated in lung related inflammatory conditions and diseases, including allergic asthma, but not to toxicity of environmental low-molecular-weight chemicals. We investigated effects of toluene diisocyanate (TDI) on ATX induction in human lung epithelial cell models, and we correlated LPA-levels in plasma to biomarkers of TDI exposure in urine collected from workers exposed to < 5 ppb (parts per billion). Information on workers' symptoms was collected through interviews. One nanomolar TDI robustly induced ATX release within 10 min in vitro. A P2X7- and P2X4-dependent microvesicle formation was implicated in a rapid ATX release and a subsequent protein synthesis. Co-localization between purinergic receptors and ATX was documented by immunofluorescence and confocal microscopy. The release was modulated by monocyte chemoattractant protein-1 (MCP-1) and by extracellular ATP. In workers, we found a dose–response relationship between TDI exposure biomarkers in urine and LPA levels in plasma. Among symptomatic workers reporting “sneezing”, the LPA levels were higher than among non-symptomatic workers. This is the first report indicating induction of the ATX-LPA axis by an environmental low-molecular-weight chemical, and our data suggest a role for the ATX-LPA axis in TDI toxicity. - Highlights: • Human epithelial cells release autotaxin in response to 1 nM toluene diisocyanate (TDI). • The release involves P2X4 and P2X7 receptors and is modulated by ATP and MCP-1. • Lysophosphatidic acid (LPA) was measured in workers exposed to < 5 ppb TDI. • LPA in plasma correlated to TDI exposure

  5. Warfarin binding to plasma of workers exposed to toluene diisocyanate

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, K.; Shapiro, R.; Forney, R.B. Jr.

    1982-02-01

    The extent of (14)C-warfarin binding to plasma proteins was evaluated in a group of normal, healthy volunteers and in two groups of individuals occupationally exposed to toluene diisocyanate (TDI). Plasma binding was assessed by ultrafiltration after the addition of racemic (14)C-warfarin to a final concentration of 0.8 microgram/ml. Chronic occupational exposure to TDI did not affect the extent of warfarin binding since warfarin free fractions (normalized to an albumin concentration of 4.5 g/dl) were 1.09 +/- 0.23 (mean +/- SD), 0.98 +/- 0.19, and 0.97 +/- 0.15 for controls and the two groups of TDI-exposed individuals, respectively.

  6. Skin exposure to aliphatic polyisocyanates in the auto body repair and refinishing industry: II. A quantitative assessment.

    Science.gov (United States)

    Bello, Dhimiter; Redlich, Carrie A; Stowe, Meredith H; Sparer, Judy; Woskie, Susan R; Streicher, Robert P; Hosgood, H Dean; Liu, Youcheng

    2008-03-01

    Skin exposure to isocyanates, in addition to respiratory exposures, may contribute to sensitization and asthma. Quantitative skin exposure data are scarce and quantitative methods limited. As part of the Survey of Painters and Repairers of Autobodies by Yale study, a method to sample and quantify human isocyanate skin exposure was developed (based on NIOSH 5525 method) and used to evaluate aliphatic isocyanate skin exposure in 81 auto body shop painters and body technicians. Wipe samples were collected from unprotected skin and from under PPE (gloves, clothing and respirator) using a polypropylene glycol-impregnated wipe. Hexamethylene diisocyanate (HDI), its polyisocyanates [HDI-derived polyisocyanates (pHDI)], isophorone diisocyanate (IPDI) and its polyisocyanates and IPDI-derived polyisocyanates (pIPDI) were quantified separately and also expressed as the total free isocyanate groups (total NCO). For unprotected skin areas, 49 samples were collected for spray painting, 13 for mixing, 27 for paint-related tasks (e.g. sanding and compounding) and 53 for non-paint-related tasks. Forty-three samples were also collected under PPE. The geometric mean (GM) [geometric standard deviation (GSD)] total NCO concentrations (ng NCO cm(-2)) for unprotected skin (hands, face and forearms) was 1.9 (10.9) and range 0.0-64.4. pHDI species were the major contributor to the total NCO content. Levels were very variable, with the highest concentrations measured for clear coating and paint mixing tasks. Isocyanate skin exposure was also commonly detected under PPE, with 92% of samples above the limit of detection. Levels were very variable with the overall GM (GSD) total NCO (ng NCO cm(-2)) under PPE 1.0 (5.2) and range (0.0-47.0) and similar under the different PPE (glove, respirator and clothing). The highest concentrations were detected for mixing and spraying tasks, 6.9 (5.3) and 1.0 (5.2), respectively. Levels under PPE were generally lower than unpaired samples obtained with no

  7. Conjugation of diisocyanate side chains to dimethacrylate reduces polymerization shrinkage and increases the hardness of composite resins.

    Science.gov (United States)

    Jan, Yih-Dean; Lee, Bor-Shiunn; Lin, Chun-Pin; Tseng, Wan-Yu

    2014-04-01

    Polymerization shrinkage is one of the main causes of dental restoration failure. This study tried to conjugate two diisocyanate side chains to dimethacrylate resins in order to reduce polymerization shrinkage and increase the hardness of composite resins. Diisocyanate, 2-hydroxyethyl methacrylate, and bisphenol A dimethacrylate were reacted in different ratios to form urethane-modified new resin matrices, and then mixed with 50 wt.% silica fillers. The viscosities of matrices, polymerization shrinkage, surface hardness, and degrees of conversion of experimental composite resins were then evaluated and compared with a non-modified control group. The viscosities of resin matrices increased with increasing diisocyanate side chain density. Polymerization shrinkage and degree of conversion, however, decreased with increasing diisocyanate side chain density. The surface hardness of all diisocyanate-modified groups was equal to or significantly higher than that of the control group. Conjugation of diisocyanate side chains to dimethacrylate represents an effective means of reducing polymerization shrinkage and increasing the surface hardness of dental composite resins. Copyright © 2012. Published by Elsevier B.V.

  8. Longitudinal and Cross-sectional Analyses of Lung Function in Toluene Diisocyanate Production Workers.

    Science.gov (United States)

    Wang, Mei Lin; Storey, Eileen; Cassidy, Laura D; Doney, Brent; Conner, Patrick R; Collins, James J; Carson, Michael; Molenaar, Don

    2017-12-01

    The aim of this study was to investigate lung function among toluene diisocyanate (TDI) production workers. One hundred ninety-seven U.S workers performed spirometry from 2006 through 2012. Results were compared within the study cohort and with U.S. population measures. A mixed-effects model assessed factors affecting repeated forced expiratory volume in 1 second (FEV1) measurements. The cohort's mean FEV1 and forced vital capacity (FVC) percent reference values, although greater than 90%, were significantly lower and the prevalence of abnormal spirometry (predominantly restrictive pattern) was significantly higher than in the U.S. Differences in lung function among workers with higher cumulative TDI exposure were in the direction of an exposure effect, but not significant. We found little evidence of an adverse effect of TDI exposure on longitudinal spirometry in these workers. The association between TDI exposure and the increasing prevalence of a restrictive pattern needs further exploration.

  9. Synthesis and characterization of thiolated carboxymethyl chitosan-graft-cyclodextrin nanoparticles as a drug delivery vehicle for albendazole.

    Science.gov (United States)

    Alamdarnejad, Ghazaleh; Sharif, Alireza; Taranejoo, Shahrouz; Janmaleki, Mohsen; Kalaee, Mohammad Reza; Dadgar, Mohsen; Khakpour, Mazyar

    2013-08-01

    A new strategy for the synthesis of thiolated carboxymethyl chitosan-g-cyclodextrin nanoparticles by an ionic-gelation method is presented. The synthetic approach was based on the utilization of 1,6-hexamethylene diisocyanate during cyclodextrin grafting onto carboxymethyl chitosan. The use of the 1,6-hexamethylene diisocyanate resulted in reactions between cyclodextrin and active sites at the C6-position of chitosan, and preserved amino groups of chitosan for subsequent reactions with thioglycolic acid, as the thiolating agent, and tripolyphosphate, as the gelling counterion. Various methods such as scanning electron microscopy, rheology and in vitro release studies were employed to exhibit significant features of the nanoparticles for mucosal albendazole delivery applications. It was found that the thiolated carboxymethyl chitosan-g-cyclodextrin nanoparticles prepared using an aqueous solution containing 1 wt% of tripolyphosphate and having 115.65 (μmol/g polymer) of grafted thiol groups show both the highest mucoadhesive properties and the highest albendazole entrapment efficiency. The latter was confirmed theoretically by calculating the enthalpy of mixing of albendazole in the above thiolated chitosan polymer.

  10. The effect of crosslinker on mechanical and morphological properties of tropical wood material composites

    International Nuclear Information System (INIS)

    Islam, Md. Saiful; Hamdan, Sinin; Rahman, Md. Rezaur; Jusoh, Ismail; Ahmed, Abu Saleh

    2011-01-01

    In this study, wood polymer composites (WPCs) based on five kinds of selected tropical wood species, namely Jelutong (Dyera costulata), Terbulan (Endospermum diadenum), Batai (Paraserianthes moluccana), Rubber (Hevea brasiliensis), and Pulai (Alstonia pneumatophora), were impregnated with methyl methacrylate (MMA) and hexamethylene diisocyanate (HMDIC) monomers mixture in the ratio of 1:1 for composite manufacturing. All these tropical wood reacted with hexamethylene diisocyanate and crosslinked with MMA which enhanced the hydrophobic (restrained water) nature of wood. The vacuum-pressure method was used to impregnate the samples with monomer mixture. The monomer mixture loading achievable was found to be dependent on the properties of wood species. Low loading was observed for the high density wood species. Mechanical strength of fabricated wood polymer composites (WPCs) in term of modulus of elasticity (MOE) and modulus of rupture (MOR) were found to be significantly improved. The wood-polymer interaction was confirmed by Fourier transform infrared (FTIR) spectroscopy. Morphological properties of raw wood and WPC samples were evaluated by scanning electron microscopy (SEM) and XRD analysis and an improvement in morphological properties was also observed for WPC.

  11. Determination of isocyanate specific albumin-adducts in workers exposed to toluene diisocyanates.

    Science.gov (United States)

    Sabbioni, Gabriele; Gu, Qi; Vanimireddy, Lakshiminiranjan Reddy

    2012-03-01

    Toluene diisocyanates (2,4-TDI and 2,6-TDI) are important intermediates in the chemical industry. Among the main damages after low levels of TDI exposure are lung sensitization and asthma. It is therefore necessary to have sensitive and specific methods to monitor isocyanate exposure of workers. Urinary metabolites or protein adducts have been used as biomarkers in workers exposed to TDI. However, with these methods it was not possible to determine if the biomarkers result from exposure to TDI or to the corresponding toluene diamines (TDA). This work presents a new procedure for the determination of isocyanate-specific albumin adducts. Isotope dilution mass spectrometry was used to measure the adducts in albumin present in workers exposed to TDI. 2,4-TDI and 2,6-TDI formed adducts with lysine: N(ϵ)-[({3-amino-4-methylphenyl}amino)carbonyl]-lysine, N(ϵ)-[({5-amino-2-methylphenyl}amino)carbonyl]-lysine, and N(ϵ)- [({3-amino-2-methylphenyl}amino)carbonyl]-lysine. In future studies, this new method can be applied to measure TDI-exposures in workers.

  12. Development of a respiratory sensitization/elicitation protocol of toluene diisocyanate (TDI) in Brown Norway rats to derive an elicitation-based occupational exposure level

    International Nuclear Information System (INIS)

    Pauluhn, Jürgen

    2014-01-01

    Highlights: • Toluene diisocyanate (TDI) was unequivocally identified as asthmagens in BN-rats. • The elicitation response on BAL-PMN was threshold-dose dependent. • The elicitation of asthma-like responses follow a concentration × time-relationship. • The human-equivalent dose–response was duplicated in rats. • The derived occupational exposure level (OEL) matches current standards. - Abstract: Toluene diisocyanate (TDI), a known human asthmagen, was investigated in skin-sensitized Brown Norway rats for its concentration × time (C × t)-response relationship on elicitation-based endpoints. The major goal of study was to determine the elicitation inhalation threshold dose in sensitized, re-challenged Brown Norway rats, including the associated variables affecting the dosimetry of inhaled TDI-vapor in rats and as to how these differences can be translated to humans. Attempts were made to duplicate at least some traits of human asthma by using skin-sensitized rats which were subjected to single or multiple inhalation-escalation challenge exposures. Two types of dose-escalation protocols were used to determine the elicitation-threshold C × t; one used a variable C (C var ) and constant t (t const ), the other a constant C (C const ) and variable t (t var ). The selection of the ''minimal irritant'' C was based an ancillary pre-studies. Neutrophilic granulocytes (PMNs) in bronchoalveolar lavage fluid (BAL) were considered as the endpoint of choice to integrate the allergic pulmonary inflammation. These were supplemented by physiological measurements characterizing nocturnal asthma-like responses and increased nitric oxide in exhaled breath (eNO). The C const × t var regimen yielded the most conclusive dose–response relationship as long C was high enough to overcome the scrubbing capacity of the upper airways. Based on ancillary pre-studies in naïve rats, the related human-equivalent respiratory tract irritant threshold

  13. Physical and Chemical Characterization of Poly(hexamethylene biguanide Hydrochloride

    Directory of Open Access Journals (Sweden)

    Luiz Henrique C. Mattoso

    2011-06-01

    Full Text Available We present the characterization of commercially available Poly(hexamethylene biguanide hydrochloride (PHMB, a polymer with biocidal activity and several interesting properties that make this material suitable as a building block for supramolecular chemistry and “smart” materials. We studied polymer structure in water solution by dynamic light scattering, surface tension and capacitance spectroscopy. It shows typical surfactant behavior due to amphiphilic structure and low molecular weight. Spectroscopic (UV/Vis, FT-NIR and thermal characterization (differential scanning calorimetry, DSC, and thermogravimetric analysis, TGA were performed to give additional insight into the material structure in solution and solid state. These results can be the foundation for more detailed investigations on usefulness of PHMB in new complex materials and devices.

  14. Proteomic analysis of erythroid differentiation induced by hexamethylene bisacetamide in murine erythroleukemia cells

    Czech Academy of Sciences Publication Activity Database

    Petrák, J.; Myslivcová, D.; Man, Petr; Čmejlová, J.; Čmejla, R.; Vyoral, D.

    2007-01-01

    Roč. 35, - (2007), s. 193-202 ISSN 0301-472X R&D Projects: GA MŠk LC545 Grant - others:CZ(CZ) 023736; GA ČR(CZ) GA303/04/0003; GA MŠk(CZ) LC06044 Institutional research plan: CEZ:AV0Z50200510 Source of funding: V - iné verejné zdroje ; V - iné verejné zdroje ; V - iné verejné zdroje Keywords : murine erythroleukemia cells * erythroid differentiation * hexamethylene bisacetamide Subject RIV: EE - Microbiology, Virology Impact factor: 3.147, year: 2007

  15. Preparation and Characterization of Antibacterial Polypropylene Meshes with Covalently Incorporated β-Cyclodextrins and Captured Antimicrobial Agent for Hernia Repair

    Directory of Open Access Journals (Sweden)

    Noor Sanbhal

    2018-01-01

    Full Text Available Polypropylene (PP light weight meshes are commonly used as hernioplasty implants. Nevertheless, the growth of bacteria within textile knitted mesh intersections can occur after surgical mesh implantation, causing infections. Thus, bacterial reproduction has to be stopped in the very early stage of mesh implantation. Herein, novel antimicrobial PP meshes grafted with β-CD and complexes with triclosan were prepared for mesh infection prevention. Initially, PP mesh surfaces were functionalized with suitable cold oxygen plasma. Then, hexamethylene diisocyanate (HDI was successfully grafted on the plasma-activated PP surfaces. Afterwards, β-CD was connected with the already HDI reacted PP meshes and triclosan, serving as a model antimicrobial agent, was loaded into the cyclodextrin (CD cavity for desired antibacterial functions. The hydrophobic interior and hydrophilic exterior of β-CD are well suited to form complexes with hydrophobic host guest molecules. Thus, the prepared PP mesh samples, CD-TCL-2 and CD-TCL-6 demonstrated excellent antibacterial properties against Staphylococcus aureus and Escherichia coli that were sustained up to 11 and 13 days, respectively. The surfaces of chemically modified PP meshes showed dramatically reduced water contact angles. Moreover, X-ray diffractometer (XRD, differential scanning calorimeter (DSC, and Thermogravimetric (TGA evidenced that there was no significant effect of grafted hexamethylene diisocyanate (HDI and CD on the structural and thermal properties of the PP meshes.

  16. The Development of Testing Methods for Characterizing Emissions and Sources of Exposures from Polyurethane Products

    Science.gov (United States)

    The relationship between onsite manufacture of spray polyurethane foam insulation (SPFI) and potential exposures is not well understood. Currently, no comprehensive standard test methods exist for characterizing and quantifying product emissions. Exposures to diisocyanate compoun...

  17. [Determination of residual toluene diisocyanate in sponge bra by gas chromatography].

    Science.gov (United States)

    Wang, Aixia; Ye, Ping; Huang, Nan; Chen, Yan; Li, Xinggen

    2017-06-08

    A gas chromatography (GC) with internal standard method was developed for the determination of residual toluene diisocyanate (TDI) in sponge bra. The samples were extracted with ethyl acetate dehydrated, and cleaned up with 0.22 μm microfiltration membrane. The residual toluene diisocyanate was separated on a DB-624 capillary column using temperature programming. The flame ionization detector (FID) was used at 250 ℃. The inlet temperature was 180 ℃ with nitrogen as carrier gas. The linear range was 10-200 mg/L ( R 2 =0.9989) for TDI. The average recovery ranged from 80.5% to 91.6% with RSD not more than 7.9%( n =6). The limit of detection (LOD) and limit of quantification (LOQ) were 10 mg/kg and 100 mg/kg, respectively. The developed method was then utilized to analyse the 100 batches of sponge bra samples from the manufacturing enterprises, the entity shops and electric business platforms. The method is simple, time-saving and environment friendly with high sensitivity and good reproducibility, and has practical application value due to its low-cost and short-circle.

  18. Morphological effects of single-layer graphene oxide in the formation of covalently bonded polypyrrole composites using intermediate diisocyanate chemistry

    International Nuclear Information System (INIS)

    Whitby, Raymond L. D.; Korobeinyk, Alina; Mikhalovsky, Sergey V.; Fukuda, Takahiro; Maekawa, Toru

    2011-01-01

    Single-layer graphene oxide (SLGO) possesses carboxylic and hydroxyl groups suitable for reactions with aliphatic or aromatic diisocyanate molecules. TEM analysis reveals that aliphatic diisocyanate molecules caused SLGO to scroll into star-like formations, whereas aromatic diisocyanate molecules retained SGLO in a flat-sheet morphology. TGA confirms the stabilisation of the formed urea and urethane groups on SLGO, but the onset of sheet pyrolysis occurs at a lower temperature due to isocyanate reactions with anhydride and epoxide groups embedded in the sheet. Pendant isocyanate groups act as bridging units to facilitate the attachment of pyrrole molecules, which are then used as anchor sites for the covalent polymerisation of pyrrole to polypyrrole (PPy). The use of FeCl 3 as the polymerisation catalyst generated both covalent and free PPy, but also iron hydroxide nanoparticles were observed decorating the SLGO surface. When using ammonium persulfate as a catalyst and dodecylbenzenesulfonate as a dopant, free PPy could be removed under treatment with solvents to leave a purely covalent system. Discrete regions of SLGO were observed decorated with nanoparticles of PPy along the edge or across the surface of individual sheets. It was found that the flexibility of the SLGO sheet and the type of diisocyanate used directly affected the electrical resistance of the final composite.

  19. Waterborne polyurethane single-ion electrolyte from aliphatic diisocyanate and various molecular length of polyethylene glycol

    Directory of Open Access Journals (Sweden)

    2007-03-01

    Full Text Available The waterborne polyurethane (WPU dispersions from the reaction of cycloaliphatic diisocyanates [4,4’-methylenebis(cyclohexyl isocyanate (H12MDI and isophorone diisocyanate (IPDI] and polyethylene glycol (PEG with various molecular lengths were synthesized using our modified acetone process. Differetial scanning calorimeter (DSC and Fourier transform infrared spectroscopy (FTIR were utilized to characterize WPU films for the behavior of their crystallinity and H-bonding of WPU films. The Tg value of WPU increases with increasing the molecular length of PEG, whereas the Tm of WPU decreases with increasing PEG length. Alternating current (AC impedance experiments were performed to determine the ionic conductivities of WPU films. The WPU gel electrolytes exhibits an ionic conductivity as high as ~ 10-5 S/cm at room temperature.

  20. Catalytic synthesis of aromatic diisocyanates by means of carbonylation of nitrocompounds with carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Nefedov, B K; Manov-Yuvenskii, V I; Khoshdurdev, Kh O; Novikov, S S [AN SSSR, Moscow. Inst. Organicheskoj Khimii

    1977-02-11

    The development of an active and selective heterogeneous catalyst for synthesis of aromatic diisocyanates has been studied. The catalytic ability of the catalyst PdO-MoO/sub 3/-Fe/sub 2/O/sub 3/ deposited on ..gamma..-Al/sub 2/O/sub 3/ has been investigated in the reactions of carbonylation of aromatic dinitrocompounds with carbon oxide. The effect of the catalyst composition, method of catalyst production, reaction temperature and pressure on the catalytic ability have been studied. It has been established that the catalyst PdO-MoO/sub 3/-Fe/sub 2/O/sub 3/(2-6:1:1) deposited on ..gamma..-Al/sub 2/O/sub 3/ is highly active and selective in the reactions of carbonilation of aromatic dinitrocompounds at 210 deg and 300 atm. It has been used for synthesis of aromatic diisocyanates in yield 32-75%.

  1. Understanding Factors that Influence Protective Glove Use among Automotive Spray Painters

    Science.gov (United States)

    Ceballos, Diana; Reeb-Whitaker, Carolyn; Glazer, Patricia; Murphy-Robinson, Helen; Yost, Michael

    2017-01-01

    Dermal contact with isocyanate-based coatings may lead to systemic respiratory sensitization. The most common isocyanates found in sprayed automotive coatings are monomeric and oligomeric 1,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). Most spray painters use thin (4–5 mil) latex gloves that are not effective at preventing dermal exposures when spraying isocyanate paints. Personal interviews with collision repair industry personnel and focus groups with spray painters were held to characterize risk awareness, to examine perceptions and challenges concerning protective glove use and selection, and to generate ideas for protective glove use interventions. The most popular gloves among spray painters were thin (4–5 mil) and thick (14 mil) latex. We found that medium to thick (6–8 mil) nitrile were not always perceived as comfortable and were expected to be more expensive than thin (4–5 mil) latex gloves. Of concern is the users’ difficulty to distinguish between nitrile and latex gloves; latex gloves are now sold in different colors including blue, which has traditionally been associated with nitrile gloves. Even though spray painters were familiar with the health hazards related to working with isocyanate paints; most were not always aware that dermal exposure to isocyanates could contribute to the development of occupational asthma. There is a need for more research to identify dermal materials that are protective against sprayed automotive coatings. Automotive spray painters and their employers need to be educated in the selection and use of protective gloves, specifically on attributes such as glove material, color, and thickness. PMID:24215135

  2. Thermally reversible cross-linked poly(ether-urethanes

    Directory of Open Access Journals (Sweden)

    V. Gaina

    2013-07-01

    Full Text Available Cross-linked poly(ether-urethanes were prepared by Diels-Alder (DA reaction of the furan-containing poly(ether-urethane to bismaleimides and showed thermal reversibility evidenced by differential scanning calorimetry and attenuated total reflectance in conjunction with Fourier transform infrared spectroscopy (ATR-FTIR. The furan-containing poly(ether-urethanes were synthesized by the polyaddition reaction of 1,6-hexamethylene diisocyanate (HMDI or 4,4'- dibenzyl diisocyanate (DBDI to poly(tetramethylene ether glycol (PTMEG having Mn = 250, 650, 1000, 1500 and 2000 and 2-[N,N-bis(2-methyl-2-hydroxyethylamino]furfuryl as chain extender by the solution prepolymer method. The molar ratio of isocyanate: PTMEG:chain extender varied from 2:1:1 to 4:1:3, which produces a molar concentration of furyl group ranging between 3.65•10–4 and 1.25•10–3 mol/g.

  3. Refractive index modulation in the polyurethane films containing diazo sulfonamide chromophores

    Energy Technology Data Exchange (ETDEWEB)

    Ortyl, E. [Insitute of Organic and Polymer Technology, WrocIaw University of Technology, 50-384 WrocIaw (Poland); Kucharski, S. [Insitute of Organic and Polymer Technology, WrocIaw University of Technology, 50-384 WrocIaw (Poland)]. E-mail: stanislaw.kucharski@pwr.wroc.pl; Gotszalk, T. [Faculty of Microsystem Electronics and Photonics, WrocIaw University of Technology, 50-384 WrocIaw (Poland)

    2005-05-23

    The series of photochromic polyurethanes was obtained by modification of precursor polymers prepared from 4,4'-diphenylmethane diisocyanate (MDI), hexamethylene 1,6-diisocyanate (HDI) or toluene 2,4-diisocyanate (TDI) and N,N'-di-(2-hydroxyethyl) aniline. The precursor polymers were functionalized by an azo-coupling reaction to form the polymers with different degrees of functionalization and various heterocyclic sulfonamide groups. Ellipsometric measurements showed a decrease of the refractive index during illumination of thin polymer films with white light. The change of real part of the refractive index was in the range of 0.0033-0.0296 depending on the polymer kind and chromophore content. It was found that photocurrent was generated in the polymer films deposited onto indium tin oxide (ITO) glass plates. For the polyurethanes containing sulfathiazole groups in side chains the current density was up to 180 nA/cm{sup 2}. The formation of diffraction grating in the polymer films was easily achieved using linearly polarized laser light (532 nm) in a standard two beam coupling (TBC) system. The diffraction efficiency of the first diffraction beam was dependent on the chromophore content reaching ca. 12% for the derivatives of sulfamethoxazole.

  4. Conjugation of diisocyanate side chains to dimethacrylate reduces polymerization shrinkage and increases the hardness of composite resins

    Directory of Open Access Journals (Sweden)

    Yih-Dean Jan

    2014-04-01

    Conclusion: Conjugation of diisocyanate side chains to dimethacrylate represents an effective means of reducing polymerization shrinkage and increasing the surface hardness of dental composite resins.

  5. Determination of airborne isocyanates generated during the thermal degradation of car paint in body repair shops.

    Science.gov (United States)

    Boutin, Michel; Dufresne, André; Ostiguy, Claude; Lesage, Jacques

    2006-06-01

    Polyurethanes are widely used in car paint formulations. During thermal degradation, such polymeric systems can generate powerful asthmatic sensitizing agents named isocyanates. In body repair shops, the thermal degradation of car paint can occur during abrasive processes that generate enough heat to involve release of isocyanates in air. An environmental monitoring study was performed in two body repair training schools and in a body repair shop to evaluate the workers' exposure to isocyanates during cutting, grinding and orbital sanding operations. For sampling, cassettes containing two 1-(2-methoxyphenyl)piperazine (MOPIP)-coated glass fiber filters (MFs) ( approximately 5 mg of MOPIP per filter) and bubblers containing 15 ml of MOPIP solution in toluene (1.0 mg ml(-1)) backed at the outlet with cassettes containing two MFs were used. Tandem mass spectrometry was used to analyze the MOPIP derivatives of isocyanic acid (HNCO), all the linear aliphatic isocyanates ranging from methyl isocyanate (Me-i) to hexyl isocyanate, all the alkenyl isocyanates ranging from propylene isocyanate to hexylene isocyanate, 1,6-hexamethylene diisocyanate (HDI), trans- and cis-isophorone diisocyanate (IPDI), 2,4- and 2,6-toluene diisocyanate (TDI), 2,4'-; 2,2'- and 4,4'-methylenediphenyl diisocyanate (MDI), phenyl isocyanate (Ph-i) and p-toluene isocyanate (p-Tol-i). The instrumental detection limits (LOD) were in the 0.13-0.75 microg of NCO per m(3) range for 15 l air samples converted into 3 ml liquid samples. The isocyanate concentrations detected in the workers' breathing zone were in the 1.07-9.80 microg of NCO per m(3) range for cutting, 0.63-3.62 microg of NCO per m(3) range for grinding and 0-1.29 microg of NCO per m(3) range for sanding. However, a rapid decrease of the isocyanate concentration was observed while moving away from the emission source. Among the isocyanates detected the most abundant were the monomers (MDI, HDI, TDI and IPDI) and Me-i.

  6. Investigation of a Biocompatible Polyurethane-Based Isotropically Conductive Adhesive for UHF RFID Tag Antennas

    Science.gov (United States)

    Yang, Cheng; Yuen, Matthew M. F.; Gao, Bo; Ma, Yuhui; Wong, C. P.

    2011-01-01

    As a candidate dispersant for silver-based isotropically conductive adhesives (ICAs), polyurethane (PU) is an environmentally benign material that can withstand a high deformation rate and that exhibits excellent reliability. In this work we investigated methyl ethyl ketoxime (MEKO) blocked isophorone diisocyanate (IPDI) and MEKO blocked hexamethylene diisocyanate (HDI) as dispersant materials, and we characterize the electrical conductivity, mechanical properties, and reliability of these PU-based ICAs with silver-flake filler content ranging from 30 wt.% to 75 wt.%. Results of temperature-humidity testing (THT) at 85°C and 85% relative humidity (RH) and thermal cycling testing (TCT) at -40°C to 125°C show that these ICAs have excellent reliability. Our experimental results suggest that the MEKO blocked PU dispersants are suitable for preparing ultralow-cost, flexible, high-performance ICAs for printing antennas for ultrahigh-frequency radiofrequency identification (RFID) tags. These tags can potentially be used for identifying washable items and food packaging.

  7. Determination of albumin adducts of 4,4'-methylenediphenyl diisocyanate after specific inhalative challenge tests in workers.

    Science.gov (United States)

    Sabbioni, Gabriele; Dongari, Nagaraju; Kumar, Anoop; Baur, Xaver

    2016-10-17

    4,4'-Methylenediphenyl diisocyanate (MDI) is the most important isocyanate used in the industry. Lung sensitization with bronchial asthma is the main disorder in exposed workers. Albumin adducts of MDI might be involved in specific immunological reactions. MDI adducts with lysine (MDI-Lys) of albumin have been found in MDI-workers and construction workers. MDI-Lys is an isocyanate-specific adduct of MDI with albumin. In the present study, we report MDI-adducts in workers undergoing diagnostic MDI challenge tests. The workers were exposed for 2h to 5ppb of MDI. The adduct levels increase significantly after the exposure to MDI in the challenge chamber. About 0.6% of the dose was bound to albumin. So far, only urinary metabolites of MDI were measured to monitor isocyanate workers. However, such urinary metabolites are not isocyanate specific. Therefore, we propose to measure albumin adducts for monitoring MDI exposed subjects. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Transport behavior of n-alkane penetrants into castor oil based polyurethane-polyester nonwoven fabric composites

    International Nuclear Information System (INIS)

    Satheesh Kumar, M.N.; Manjula, K.S.; Siddaramaiah

    2007-01-01

    Castor oil based polyurethane (PU)-polyester nonwoven fabric composites were fabricated by impregnating the polyester nonwoven fabric in a composition containing castor oil and diisocyanate. Composites were fabricated with two different isocyanates such as toluene-2,4-diisocyanate (TDI) and hexamethylene diisocyanate (HMDI). Transport behavior of n-alkane penetrants (pentane, hexane and heptane) into both PUs and PU-polyester nonwoven fabric composites were studied. Sorption studies were carried out at different temperatures. From the sorption results, the diffusion (D) and permeation (P) coefficients of penetrants have been calculated. Significant increase in the diffusion and permeation coefficients was observed with increase in the temperature of sorption experiments. Drastical reduction in diffusion and permeation coefficients was noticed in the composites compared to neat PUs. Attempts were made to estimate the empirical parameters like n, which suggests the mode of transport and K is a constant depends on the structural characteristics of the composite in addition to its interaction with penetrants. The temperature dependence of the transport coefficients has been used to estimate the activation energy parameter for diffusion (E D ) and permeation (E P ) processes from Arrhenius plots. Furthermore, the sorption results have been interpreted in terms of the thermodynamic parameters such as enthalpy (ΔH) and entropy (ΔS)

  9. Retinoic acid, hemin and hexamethylen bisacetamide interference with "in vitro" differentiation of chick embryo chondrocytes.

    Science.gov (United States)

    Manduca, P; Abelmoschi, M L

    1992-01-01

    We have investigated the effect of all-trans Retinoic acid, and of substances (Hemine and Hexamethylene bisacetamide) which interfere with "in vitro" differentiation of mesenchyme derived cell lineages on the expression of specific markers of hyperthrophy in "in vitro" differentiating chick embryo chondrocytes. (Castagnola P., et al., 1986). Continuous treatment of chondrogenic cells in conditions allowing differentiation "in vitro" with Retinoic acid resulted in persistence of type I collagen synthesis and in lack of type X collagen and Ch 21 protein expression. Hemin treated cells secreted a reduced amount of type X collagen. HMBA treatment inhibited type X collagen expression and caused reduction of the ratio between type II collagen and Ch 21 synthesized. The data indicate an independent regulation of these markers during chondrocyte differentiation.

  10. IL-4 and IL-5 Secretions Predominate in the Airways of Wistar Rats Exposed to Toluene Diisocyanate Vapor

    Directory of Open Access Journals (Sweden)

    Kouame Kouadio

    2014-01-01

    Full Text Available ObjectivesWe established a Wistar rat model of asthma caused by toluene diisocyanate (TDI exposure, and investigated the relationship between TDI exposure concentrations and respiratory hypersensitivity, airway inflammation, and cytokine secretions in animals, to better understand the mechanism of TDI induced occupational asthma.MethodsWistar rats were exposed to two different concentrations of TDI vapor four hours a day for five consecutive days. Bronchoalveolar lavage (BAL was performed, and differential leucocytes from the BAL fluid were analyzed. Lung histopathological examination was carried out to investigate the inflammatory status in the airways. Production of cytokines interleukin (IL-4 and IL-5 productions in the BAL fluid in vivo was determined with enzyme-linked immunosorbent assay kits.ResultsThe TDI-exposed rats exhibited greater airway hypersensitivity symptoms than the control rats. The BAL differential cell count and lung histopathological examination demonstrated that inflammation reactions were present in both the central and peripheral airways, characterized with marked infiltration of eosinophils in the TDI-exposed rats. The cytokine assay showed that IL-4 and IL-5 were predominantly produced in the BAL fluid in vivo.ConclusionsThese findings imply that TDI exposure concentrations may greatly affect the occurrence and extent of inflammatory events and that Th2 type cytokines may play an important role in the immunopathogenesis of TDI-induced occupational respiratory hypersensitivity.

  11. Preparation and properties of new cross-linked polyurethane acrylate electrolytes for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, P.; Vasudevan, T.; Gopalan, A. [Department of Industrial Chemistry, Alagappa University, Karaikudi-630 003 (India); Lee, Kwang-Pill [Department of Chemistry Education, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

    2006-09-29

    A cross-linked polyurethane acrylate (PUA) is synthesized by end-capping a hexamethylene diisocyanate, hexamethylene diisocyanate/poly(ethylene glycol)-based prepolymer with hydroxy butyl methacrylate (HBMA). Significant interactions of lithium ions with the soft and hard segments of the host polymer are observed for the PUA complexed with lithium perchlorate (LiClO{sub 4}) by means of differential scanning calorimetry (DSC), and Fourier transform infra-red (FT-IR) spectroscopy measurements. The DSC results indicate the formation of transient cross-links with the ether oxygen of the soft segment and mixing of soft and hard phases induced by the Li{sup +} ions. The results of FT-IR spectroscopy and thermogravimetric analysis measurements support the formation of different types of complexes by interaction of Li{sup +} ions with different coordination sites of PUA. No detectable interactions are found between Li{sup +} ions and groups in HBMA. In addition, PUA follows the Arrhenius relationship for ion transport. Predominant formation of contact ion-pairs of LiClO{sub 4} is observed through a.c. conductivity and DSC measurements. The lithium stripping-plating process is reversible and this implies better electrochemical stability over the working voltage range. Also, the PUA electrolyte shows better compatibility with lithium metal as inferred from impedance measurements and has a good cationic transference number that is suitable for the material to be used as a solid polymer electrolyte. Addition of HBMA into the PU matrix improves the tensile strength of the cross-linked PUA. Swelling measurements of PUA with plasticizer indicate better dimensional stability. A cell is constructed with PUA as the electrolyte and its performance is evaluated. (author)

  12. Toluene diisocyanate concentration investigation among TDI-related factories in Taiwan and their relations to the type of industry.

    Science.gov (United States)

    Yeh, Hui-Jung; Shih, Tung-Sheng; Tsai, Perng-Jy; Chang, Ho-Yuan

    2002-03-01

    To determine nationwide 2,4- and 2,6-toluene diisocyanates (TDI) concentrations among polyurethane (PU) resin, PU foam, and other TDI-related industries in Taiwan. The ratios of 2,4-/2,6-TDI and the noncarcinogenic risk among these three industries were also investigated. Personal and fixed-area monitoring of TDI concentrations as well as questionnaires were performed for 26 factories in Taiwan. The modified OHSA 42 method was applied in sampling and analysis. Noncarcinogenic hazard index was estimated for these three industries based on the average concentration measurements. Significant differences of TDI concentrations were found among the three industry categories. For personal monitoring, PU foam was found to have the highest TDI levels [18.6 (+/-33.6) and 22.1 (+/-42.3) ppb for 2,4- and 2,6-TDI], Others average [8.3 (+/-18.9) and 10.2 (+/-17.2) ppb], and PU resin lowest [2.0 (+/-3.5) and 0.7 (+/-1.2) ppb]. The estimated average hazard indices were found to be 310-3310. A substantial percentage of airborne TDI concentrations among in Taiwan industries exceeded current TDI occupational exposure limit, and significant difference of TDI levels were found among the three industry categories. The control remedy for the tasks of charging and foaming should be enforced with the highest priority. A separate 2,6-TDI exposure standard is warranted.

  13. Biological monitoring of isocyanates and related amines. I. Determination of 1,6-hexamethylene diamine (HDA) in hydrolysed human urine after oral administration of HDA.

    Science.gov (United States)

    Brorson, T; Skarping, G; Sandström, J F; Stenberg, M

    1990-01-01

    1,6-Hexamethylene diamine (HDA), used as raw material in industrial manufacturing operations, was orally administered to six healthy volunteers. After acid hydrolysis of the urine by hydrochloric acid, HDA and the metabolite 6-aminohexanoic acid were quantified. HDA was determined as an ethyl-chloroformate derivative by capillary gas chromatography using thermionic specific detection (TSD), and 6-aminohexanoic acid was quantified by ion chromatography using the ninhydrin reaction. In nonhydrolysed urine, monoacetylated HDA (N-acetyl-1,6-hexamethylene diamine) and HDA, were verified as heptafluorobutyric anhydride derivatives by gas chromatography-mass spectrometry (GC-MS), in a chemical ionization mode using isobutane and ammonia as reagent gases. In hydrolysed urine, a mean of 0.28 mg (range 1-6%) of the administered dose (8.2 mg) was recovered as HDA, and a mean of 0.8 mg (range less than 1-27%) as 6-aminohexanoic acid. The urinary excretion of both the determined compounds was rapid, and the principal part (greater than 90%) of the elimination was completed within 10 h. There was a considerable inter-individual variation in the excreted amounts, but the intra-individual variation in the excretion of HDA was limited. The subjects N-acetylator phenotype was determined by a dapsone test. Three slow acetylators excreted lower amounts (mean 2% of given dose) of HDA than three rapid ones (mean 5%).

  14. Assessing isocyanate exposures in polyurethane industry sectors using biological and air monitoring methods.

    Science.gov (United States)

    Creely, K S; Hughson, G W; Cocker, J; Jones, K

    2006-08-01

    Isocyanates, as a chemical group, are considered to be the biggest cause of occupational asthma in the UK. Monitoring of airborne exposures to total isocyanate is costly, requiring considerable expertise, both in terms of sample collection and chemical analysis and cannot be used to assess the effectiveness of protection from wearing respiratory protective equipment (RPE). Biological monitoring by analysis of metabolites in urine can be a relatively simple and inexpensive way to assess exposure to isocyanates. It may also be a useful way to evaluate the effectiveness of control measures in place. In this study biological and inhalation monitoring were undertaken to assess exposure in a variety of workplaces in the non-motor vehicle repair sector. Companies selected to participate in the survey included only those judged to be using good working practices when using isocyanate formulations. This included companies that used isocyanates to produce moulded polyurethane products, insulation material and those involved in industrial painting. Air samples were collected by personal monitoring and were analysed for total isocyanate content. Urine samples were collected soon after exposure and analysed for the metabolites of different isocyanate species, allowing calculation of the total metabolite concentration. Details of the control measures used and observed contamination of exposed skin were also recorded. A total of 21 companies agreed to participate in the study, with exposure measurements being collected from 22 sites. The airborne isocyanate concentrations were generally very low (range 0.0005-0.066 mg m(-3)). A total of 50 of the 70 samples were polyurethane foam insulation (0.023 mg m(-3)). The most commonly detected isocyanate in the urine was hexamethylene diisocyanate, which was detected in 21 instances. The geometric mean total isocyanate metabolite concentration for the dataset was 0.29 micromol mol(-1) creatinine (range 0.05-12.64 micromol mol(-1

  15. Airborne concentrations of methylene diphenyl diisocyanate (MDI) in North American wood mills during the manufacturing of oriented strand board (OSB).

    Science.gov (United States)

    Karoly, William J; Flatley, John J; Stevenson, Ralph D; Bowers, John D

    2004-12-01

    Air monitoring data were collected from industrial hygiene surveys over an 8-year period in oriented strand board (OSB) mills. Personal samples were taken to evaluate potential employee exposures to MDI. Area samples were taken to determine the effectiveness of control measures used in the mills to prevent fugitive emissions of wood dust, MDI, and MDI-coated wood dust from the OSB manufacturing process. Personal sampling results (578 samples covering 11 different job categories) ranged from 0.0002-0.524 mg/m3, with a GM = 0.001 and GSD = 3.71. Area sampling results (1657 samples covering 14 stationary locations in the mills) ranged from 0.0002-2.5 mg/m3, with a GM = 0.004 and GSD = 5.52. The statistical range of the data suggests high variability. While exposures to MDI above the established limits (0.051 mg/m3, 8-hour time-weighted average, 0.2 mg/m3, ceiling) can and do occur when engineering controls are not maintained and/or proper work practices and personal protective equipment are not followed/used for certain high exposure potential tasks, the data indicate that over 97% of the personal and 92% of the area sampling results are less than 0.051 mg/m3. Wipe testing was performed to determine the presence of removable, unreacted diisocyanates (NCO functional groups)from various surfaces. Positive results were found in about 13% of the wipe tests on surfaces confined to the blender, forming line, and hopper deck process areas.

  16. Synthesis and molecular characterization of chitosan based polyurethane elastomers using aromatic diisocyanate.

    Science.gov (United States)

    Zia, Khalid Mahmood; Anjum, Sohail; Zuber, Mohammad; Mujahid, Muhammad; Jamil, Tahir

    2014-05-01

    The present research work was performed to synthesize a new series of chitosan based polyurethane elastomers (PUEs) using poly(ɛ-caprolactone) (PCL). The chitosan based PUEs were prepared by step-growth polymerization technique using poly(ɛ-caprolactone) (PCL) and 2,4-toluene diisocyanate (TDI). In the second step the PU prepolymer was extended with different mole ratios of chitosan and 1,4-butane diol (BDO). Molecular engineering was carried out during the synthesis. The conventional spectroscopic characterization of the synthesized samples using FT-IR confirms the existence of the proposed chitosan based PUEs structure. Internal morphology of the prepared PUEs was studied using SEM analysis. The SEM images confirmed the incorporation of chitosan molecules into the PU backbone. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Determination of hexamethylene tetramine in the process solution of sol-gel method for nuclear fuel fabrication

    International Nuclear Information System (INIS)

    Ganatra, V.R.; Sawant, R.M.; Chaudhuri, N.K.; Vaidya, V.N.

    1998-01-01

    Hexamethylene tetramine (HMTA) was determined in the presence of large quantities of urea, formaldehyde and ammonium hydroxide by potentiometric titration with perchloric acid solution using an autotitrator coupled to a personal computer. This analysis is required for the process control of the sol-gel method in the production of ceramic metal oxide (e.g., oxides and mixed oxides of Th, U and Pu) microspheres using the internal gelation route. Feed solution used for preparation of microspheres contains large quantities of urea. The washings of gel microspheres produced after the internal gelation process contain urea, formaldehyde, urea-formaldehyde complex and ammonium hydroxide. The presence of these constituents in the feed solution and washings seriously interfere in the commonly used methods for the determination of HMTA. Using this method the relative standard deviation was found to be 0.27% in eleven determinations of a typical feed solution (3.0M HMTA) when the aliquots contained 75 to 125 mg of HMTA. Time required for each titration was 5-7 minutes. Feed and effluent solutions of sol-gel process were analysed. (author)

  18. Removal of Parabens from Aqueous Solution Using β-Cyclodextrin Cross-Linked Polymer

    Directory of Open Access Journals (Sweden)

    Mhd Radzi Bin Abas

    2010-09-01

    Full Text Available The removal of four parabens, methyl-, ethyl-, propyl-, and benzyl-paraben, by β-cyclodextrin (β-CD polymer from aqueous solution was studied. Different β-CD polymers were prepared by using two cross-linkers, i.e., hexamethylene diisocyanate (HMDI and toluene-2,6-diisocyanate (TDI, with various molar ratios of cross-linker. β-CD-HMDI polymer with molar ratio of 1:7 and β-CD-TDI polymer with ratio 1:4 gave the highest adsorption of parabens among the β-CD-HMDI and β-CD-TDI series, and were subsequently used for further studies. The adsorption capacity of β-CD-HMDI is 0.0305, 0.0376, 0.1854 and 0.3026 mmol/g for methyl-, ethyl-, propyl-, and benzyl-paraben, respectively. β-CD-TDI have higher adsorption capacities compared with β-CD-HMDI, the adsorption capacity are 0.1019, 0.1286, 0.2551, and 0.3699 mmol/g methyl-, ethyl-, propyl-, and benzyl-paraben respectively. The parameters studied were adsorption capacity, water retention, and reusability. Role of both cross-linker in adsorption, hydrophobicity of polymers, and adsorption capacity of different parabens were compared and discussed. All experiments were conducted in batch adsorption technique. These polymers were applied to real samples and showed positive results.

  19. New biobased high functionality polyols and their use in polyurethane coatings.

    Science.gov (United States)

    Pan, Xiao; Webster, Dean C

    2012-02-13

    High-functionality polyols for application in polyurethanes (PUs) were prepared by epoxide ring-opening reactions from epoxidized sucrose esters of soybean oil-epoxidized sucrose soyates-in which secondary hydroxyl groups were generated from epoxides on fatty acid chains. Ester polyols were prepared by using a base-catalyzed acid-epoxy reaction with carboxylic acids (e.g., acetic acid); ether polyols were prepared by using an acid-catalyzed alcohol-epoxy reaction with monoalcohols (e.g., methanol). The polyols were characterized by using gel permeation chromatography, FTIR spectroscopy, (1)H NMR spectroscopy, differential scanning calorimetry (DSC), and viscosity measurements. PU thermosets were prepared by using aliphatic polyisocyanates based on isophorone diisocyanate and hexamethylene diisocyanate. The properties of the PUs were studied by performing tensile testing, dynamic mechanical analysis, DSC, and thermogravimetric analysis. The properties of PU coatings on steel substrates were evaluated by using ASTM methods to determine coating hardness, adhesion, solvent resistance, and ductility. Compared to a soy triglyceride polyol, sucrose soyate polyols provide greater hardness and range of cross-link density to PU thermosets because of the unique structure of these macromolecules: well-defined compact structures with a rigid sucrose core coupled with high hydroxyl group functionality. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Acyclic N-halamine-immobilized polyurethane: Preparation and antimicrobial and biofilm-controlling functions

    Science.gov (United States)

    Luo, Jie; Porteous, Nuala; Lin, Jiajin; Sun, Yuyu

    2015-01-01

    Hydroxyl groups were introduced onto polyurethane surfaces through 1,6-hexamethylene diisocyanate activation, followed by diethanolamine hydroxylation. Polymethacrylamide was covalently attached to the hydroxylated polyurethane through surface grafting polymerization of methacrylamide using cerium (IV) ammonium nitrate as an initiator. After bleach treatment, the amide groups of the covalently bound polymethacrylamide chains were transformed into N-halamines. The new N-halamine-immobilized polyurethane provided a total sacrifice of 107–108 colony forming units per milliliter of Staphylococcus aureus (Gram-positive bacteria), Escherichia coli (Gram-negative bacteria), and Candida albicans (fungi) within 10 min and successfully prevented bacterial and fungal biofilm formation. The antimicrobial and biofilm-controlling effects were both durable and rechargeable, pointing to great potentials of the new acyclic N-halamine-immobilized polyurethane for a broad range of related applications. PMID:26089593

  1. Protic Cationic Oligomeric Ionic Liquids of the Urethane Type

    DEFF Research Database (Denmark)

    Shevchenko, V. V.; Stryutsky, A. V.; Klymenko, N. S.

    2014-01-01

    Protic oligomeric cationic ionic liquids of the oligo(ether urethane) type are synthesized via the reaction of an isocyanate prepolymer based on oligo(oxy ethylene)glycol with M = 1000 with hexamethylene-diisocyanate followed by blocking of the terminal isocyanate groups with the use of amine...... derivatives of imidazole, pyridine, and 3-methylpyridine and neutralization of heterocycles with ethanesulfonic acid and p-toluenesulfonic acid. The structures and properties of the synthesized oligomeric ionic liquids substantially depend on the structures of the ionic groups. They are amorphous at room...... temperature, but ethanesulfonate imidazolium and pyridinium oligomeric ionic liquids form a low melting crystalline phase. The proton conductivities of the oligomeric ionic liquids are determined by the type of cation in the temperature range 80-120 degrees C under anhydrous conditions and vary within five...

  2. Clinical and immunologic findings of methylene diphenyl diisocyanate-induced occupational asthma in a car upholstery factory.

    Science.gov (United States)

    Hur, G-Y; Koh, D-H; Choi, G-S; Park, H-J; Choi, S-J; Ye, Y-M; Kim, K-S; Park, H-S

    2008-04-01

    Although methylene diphenyl diisocyanate (MDI) is widely used in many industries, there have been few immunological studies of MDI-induced occupational asthma. We investigated the effects of MDI exposure on the clinical and immunologic condition of workers in a single car upholstery factory. Fifty-eight MDI-exposed workers were studied. Work-related lower-respiratory symptoms (WRRS) were identified using a questionnaire. Serum-specific IgE and IgG antibodies to MDI-human serum albumin conjugate were detected by ELISA. Atopy was evaluated using a skin prick test. MDI-induced occupational asthma was confirmed in the symptomatic workers with a positive result on an MDI-specific inhalation test. Thirteen (22.4%) of the subjects complained of WRRS. MDI-induced occupational asthma was confirmed in five (8.6%) of the workers, and occupational eosinophilic bronchitis was confirmed in two (3.5%). The prevalence of specific IgG antibodies (20.7%) was higher than that of specific IgE antibodies (8.6%). The prevalence of MDI-induced occupational asthma/eosinophilic bronchitis was strongly associated with the presence of both WRRS and serum-specific IgG antibodies to an MDI-human serum albumin conjugate (Pworkers. The prevalence of MDI-induced occupational asthma was 8.6%, and MDI-induced eosinophilic bronchitis was confirmed in two workers. The presence of work-related lower-respiratory symptoms and serum-specific IgG antibodies to an MDI-human serum albumin conjugate may be used to predict MDI-induced occupational asthma/eosinophilic bronchitis in MDI-exposed workers.

  3. Using Gas Phase Reactions of Hexamethylene Triperoxide Diamine (HMTD) to Improve Detection in Mass Spectrometry

    Science.gov (United States)

    Colizza, Kevin; Yevdokimov, Alexander; McLennan, Lindsay; Smith, James L.; Oxley, Jimmie C.

    2018-01-01

    Our efforts to lower the detection limits of hexamethylene triperoxide diamine (HMTD) have uncovered previously unreported gas-phase reactions of primary and secondary amines with one of the six methylene carbons. The reaction occurs primarily in the atmospheric pressure chemical ionization (APCI) source and is similar to the behavior of alcohols with HMTD [1]. However, unlike alcohols, the amine reaction conserves the hydrogen peroxide on the intact product. Furthermore, with or without amines, HMTD is oxidized to tetramethylene diperoxide diamine dialdehyde (TMDDD) in a temperature-dependent fashion in the APCI source. Synthesized TMDDD forms very strong adducts (not products) to ammonium and amine ions in the electrospray ionization (ESI) source. Attempts to improve HMTD detection by generating TMDDD in the APCI source with post-column addition of amines were not successful. Signal intensity of the solvent related HMTD product in methanol, [HMTD+MeOH2-H2O2]+ (m/z 207.0975), was understandably related to the amount of methanol in the HMTD environment as it elutes into the source. With conditions optimized for this product, the detection of 100 pg on column was accomplished with a robust analysis of 300 pg (1.44 pmol) routinely performed on the Orbitrap mass spectrometers. [Figure not available: see fulltext.

  4. Analytical determination of specific 4,4'-methylene diphenyl diisocyanate hemoglobin adducts in human blood.

    Science.gov (United States)

    Gries, Wolfgang; Leng, Gabriele

    2013-09-01

    4,4'-Methylene diphenyl diisocyanate (MDI) is one of the most important isocyanates in the industrial production of polyurethane and other MDI-based synthetics. Because of its high reactivity, it is known as a sensitizing agent, caused by protein adducts. Analysis of MDI is routinely done by determination of the nonspecific 4,4'-methylenedianiline as a marker for MDI exposure in urine and blood. Since several publications have reported specific adducts of MDI and albumin or hemoglobin, more information about their existence in humans is necessary. Specific adducts of MDI and hemoglobin were only reported in rats after high-dose MDI inhalation. The aim of this investigation was to detect the hemoglobin adduct 5-isopropyl-3-[4-(4-aminobenzyl)phenyl]hydantoin (ABP-Val-Hyd) in human blood for the first time. We found values up to 5.2 ng ABP-Val-Hyd/g globin (16 pmol/g) in blood samples of workers exposed to MDI. Because there was no information available about possible amounts of this specific MDI marker, the analytical method focused on optimal sensitivity and selectivity. Using gas chromatography-high-resolution mass spectrometry with negative chemical ionization, we achieved a detection limit of 0.02 ng ABP-Val-Hyd/g globin (0.062 pmol/g). The robustness of the method was confirmed by relative standard deviations between 3.0 and 9.8 %. Combined with a linear detection range up to 10 ng ABP-Val-Hyd/g globin (31 pmol/g), the enhanced precision parameter demonstrates that the method described is optimized for screening studies of the human population.

  5. [Synthesis and characterization of polylactide-based thermosetting polyurethanes with shape memory properties].

    Science.gov (United States)

    Shi, Shuo; Gu, Lin; Yang, Yihu; Yu, Haibin; Chen, Rui; Xiao, Xianglian; Qiu, Jun

    2016-06-25

    A series of bio-based thermosetting polyurethanes (Bio-PUs) were synthesized by the crosslinking reaction of polylactide and its copolymers diols with hexamethylene diisocyanate (HDI) trimer. The obtained Bio-PUs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), universal tensile testing machine and cytotoxicity test. Results indicate that the PLA copolymer (P(LA-co-CL)) diols reduced the glass transition temperature (Tg) of Bio-PUs and improved their thermal stability, compared with PLA diols. The Bio-PUs synthesized from P (LA-co-CL) diols exhibit better mechanical performance and shape memory properties. Especially, Young modulus and elongation at break of the obtained Bio-PUs were 277.7 MPa and 230% respectively; the shape recovery time of the obtained Bio-PUs at body temperature was only 93 s. Furthermore, alamar blue assay results showed that the obtained Bio-PUs had no cell toxicity.

  6. Control of Mechanical Properties of Thermoplastic Polyurethane Elastomers by Restriction of Crystallization of Soft Segment

    Directory of Open Access Journals (Sweden)

    Sadaharu Nakamura

    2010-12-01

    Full Text Available Mechanical properties of thermoplastic polyurethane elastomers based on either polyether or polycarbonate (PC-glycols, 4,4’-dipheylmethane diisocyanate (1,1’-methylenebis(4-isocyanatobenzene, 1,4-butanediol, were controlled by restriction of crystallization of polymer glycols. For the polyether glycol based-polyurethane elastomers (PUEs, poly(oxytetramethylene glycol (PTMG, and PTMG incorporating dimethyl groups (PTG-X and methyl side groups (PTG-L were employed as a polymer glycol. For the PC-glycol, the randomly copolymerized PC-glycols with hexamethylene (C6 and tetramethylene (C4 units between carbonate groups with various composition ratios (C4/C6 = 0/100, 50/50, 70/30 and 90/10 were employed. The degree of microphase separation and mechanical properties of both the PUEs were investigated using differential scanning calorimetry, dynamic viscoelastic property measurements and tensile testing. Mechanical properties could be controlled by changing the molar ratio of two different monomer components.

  7. Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility.

    Science.gov (United States)

    Dawlee, S; Jayabalan, Muthu

    2011-10-01

    Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.

  8. Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility

    International Nuclear Information System (INIS)

    Dawlee, S; Jayabalan, Muthu

    2011-01-01

    Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.

  9. Thermal stability of segmented polyurethane elastomers reinforced by clay particles

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2009-01-01

    Full Text Available The aim of this work was to determine the influence of clay nanoparticles on thermal properties of segmented polyurethanes based on hexamethylene- diisocyanate, aliphatic polycarbonate diol and 1,4-butanediol as chain extender. The organically modified particles of montmorillonite and bentonite were used as reinforcing fillers. The structure of elastomeric materials was varied either by diol type or chain extender content. The ratio of OH groups from diol and chain extender (R was either 1 or 10. Thermal properties of prepared materials were determined using modulated differential scanning calorimetry (MDSC. Thermal stability of obtained elastomers has been studied by simultaneously thermogravimetry coupled with DSC. The glass transition temperature, Tg, of soft segments for all investigated samples was about -33°C. On the basis of DTG results, it was concluded that obtained materials were very stable up to 300°C.

  10. Development of segmented polyurethane elastomers with low iodine content exhibiting radiopacity and blood compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Dawlee, S; Jayabalan, Muthu, E-mail: muthujayabalan@rediffmail.com [Polymer Science Division, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala 695 012 (India)

    2011-10-15

    Biofunctionally active and inherently radiopaque polymers are the emerging need for biomedical applications. Novel segmented polyurethane elastomer with inherent radiopacity was prepared using aliphatic chain extender 2,3-diiodo-2-butene-1,4-diol, polyol polytetramethylene glycol and 4,4'-methylenebis(phenyl isocyanate) (MDI) for blood compatible applications. Aliphatic polyurethane was also prepared using hexamethylene diisocyanate for comparison. X-ray analysis of the polyurethanes revealed good radiopacity even at a relatively low concentration of 3% iodine in aromatic polyurethane and 10% in aliphatic polyurethane. The polyurethanes also possessed excellent thermal stability. MDI-based polyurethane showed considerably higher tensile strength than the analogous HDI-based polyurethane. MDI-based aromatic polyurethane exhibited a dynamic surface morphology in aqueous medium, resulting in the segregation of hydrophilic domains which was more conducive to anti-thrombogenic properties. The polyurethane was cytocompatible with L929 fibroblast cells, non-hemolytic, and possessed good blood compatibility.

  11. Highly sensitive determination of poly(hexamethylene guanidine) by Rayleigh scattering using aggregation of silver nanoparticles

    International Nuclear Information System (INIS)

    Artemyeva, Anastasia A.; Sharov, Andrei V.; Beklemishev, Mikhail K.; Samarina, Tatyana O.; Abramchuk, Sergei S.; Ovcharenko, Elena O.; Dityuk, Alexander I.; Efimov, Konstantin M.

    2015-01-01

    We have found that low concentrations of the polycationic disinfectant poly(hexamethylene guanidine) hydrochloride (PHMG) induce the aggregation of citrate-stabilized silver nanoparticles (AgNPs) in aqueous solution. Based on this finding, we have worked out a method to the determination of PHMG. The protocol includes the steps of (a) centrifuging the water sample, (b) addition of an aliquot of the colloidal solution of the AgNPs, and (c) measurement of the intensity of scattered light. The method is surprisingly selective in that comparable concentrations of surfactants, humic acids and protein do not interfere. Besides, an up to 50 mM concentration NaCl, and up to 5 mM of Mg(II) or Ca(II) are tolerated. Other cationic polyelectrolytes, polyethyleneimine and poly(dimethyldiallyammonium chloride), also cause aggregation of AgNPs but to a lesser extent. The determination of PHMG was performed in spiked samples (run-off, tap and swimming pool waters) with detection limits of 2·10 −8 , 4·10 −7 , and 6·10 −6 M (by monomer unit), respectively. The linear ranges are wider and the detection limits are lower than those of known spectrophotometric methods. It is necessary, however, to correct the calibration plot for background scattering by the sample and to establish a calibration plot for each kind of water sample. Notwithstanding this, the approach is attractive because it is sensitive, rapid, and simple. (author)

  12. Effect of toluene diisocyanate on homeostasis of intracellular-free calcium in human neuroblastoma SH-SY5Y Cells

    International Nuclear Information System (INIS)

    Liu, P.-S.; Chiung, Y.-M.; Kao, Y.-Y.

    2006-01-01

    The mechanisms of TDI (2,4-toluene diisocyanate)-induced occupational asthma are not fully established. Previous studies have indicated that TDI induces non-specific bronchial hyperreactivity to methacholine and induces contraction of smooth muscle tissue by activating 'capsaicin-sensitive' nerves resulting asthma. Cytosolic-free calcium ion concentrations ([Ca 2+ ] c ) are elevated when either capsaicin acts at vanilloid receptors, or methacholine at muscarinic receptors. This study therefore investigated the effects of TDI on Ca 2+ mobilization in human neuroblastoma SH-SY5Y cells. TDI was found to elevate [Ca 2+ ] c by releasing Ca 2+ from the intracellular stores and extracellular Ca 2+ influx. 500 μM TDI induced a net [Ca 2+ ] c increase of 112 ± 8 and 78 ± 6 nM in the presence and absence of extracellular Ca 2+ , respectively. In Ca 2+ -free buffer, TDI induced Ca 2+ release from internal stores to reduce their Ca 2+ content and this reduction was evidenced by a suppression occurring on the [Ca 2+ ] c rise induced by thapsigargin, ionomycin, and methacholine after TDI incubation. In the presence of extracellular Ca 2+ , simultaneous exposure to TDI and methacholine led a higher level of [Ca 2+ ] c compared to single methacholine stimulation, that might explain that TDI induces bronchial hyperreactivity to methacholine. We conclude that TDI is capable of interfering the [Ca 2+ ] c homeostasis including releasing Ca 2+ from internal stores and inducing extracellular Ca 2+ influx. The interaction of this novel character and bronchial hyperreactivity need further investigation

  13. Preparation and characterization of starch grafted with toluene poly (propylene oxide diisocyanate

    Directory of Open Access Journals (Sweden)

    D.C. Dragunski

    2001-01-01

    Full Text Available Amylopectin-rich starch samples (Amidex 4001 Corn Products Brasil Ingredientes Industriais Ltda. were grafted with polyethers with the purpose of obtaining new materials for application as solid polymeric electrolytes. Grafting reaction was performed by the addition of starch dissolved in DMSO to toluene poly(propylene oxide diisocyanate (Resibras dissolved in the same solvent. This reaction produced a film with good mechanical properties. The film samples were characterized by 13C-NMR, FTIR, DSC, X-Ray and SEM. The FTIR spectrum shows a sharp NH band and a very small urethane band. The 13C-NMR spectrum revealed a peak at 20 ppm, that can be attributed to the CH3 of the polyether chain, and two small peaks at 117 and 140 ppm, attributed to the aromatic ring. The X-ray diffractograms also indicated that after the grafting reaction, the samples of amylopectin-rich starch are more amorphous. Moreover, the glass transition temperature (Tg dropped from 50 °C to -11 °C. These results indicate formation of grafted products and the low Tg of the samples suggests that polyether-grafted starch is a good candidate to obtain solid polymeric electrolytes.

  14. Synthesis of polycarbonate urethane elastomers and effects of the chemical structures on their thermal, mechanical and biocompatibility properties.

    Science.gov (United States)

    Zhu, Rong; Wang, Yiyu; Zhang, Zongrui; Ma, Daiwei; Wang, Xinyu

    2016-06-01

    In this study, to obtain biomedical polyurethane elastomers with good mechanical properties and biocompatibility, a series of polycarbonate urethanes were synthesized via a two-step solution of polymerization method using the poly(1,6-hexanediol)carbonate diols (PCDL) as the soft segment, 4,4'-methylenebis(cyclohexyl isocyanate) (H12MDI), 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) as the hard segment with dibutyltin dilaurate as the catalyst. In this article, we illustrated the physical behaviors were obviously influenced by synthetic routes. And their chemical and physical structures were investigated by gel permeation chromatograph (GPC), differential scanning calorimeter (DSC), fourier transform infrared spectrography (FT-IR) and mechanical properties tests. The surface wettability were studied by contact angle measurement (CA). As a kind of short-term implant biomaterial, the results of the hemolysis and platelet adhesive tests were recorded by spectrophotometer and scanning electron microscopy (SEM), indicating the materials have a great potential for developments and applications in biomedical field.

  15. Synthesis of polycarbonate urethane elastomers and effects of the chemical structures on their thermal, mechanical and biocompatibility properties

    Directory of Open Access Journals (Sweden)

    Rong Zhu

    2016-06-01

    Full Text Available In this study, to obtain biomedical polyurethane elastomers with good mechanical properties and biocompatibility, a series of polycarbonate urethanes were synthesized via a two-step solution of polymerization method using the poly(1,6-hexanediolcarbonate diols (PCDL as the soft segment, 4,4′-methylenebis(cyclohexyl isocyanate (H12MDI, 1,6-hexamethylene diisocyanate (HDI and 1,4-butanediol (BDO as the hard segment with dibutyltin dilaurate as the catalyst. In this article, we illustrated the physical behaviors were obviously influenced by synthetic routes. And their chemical and physical structures were investigated by gel permeation chromatograph (GPC, differential scanning calorimeter (DSC, fourier transform infrared spectrography (FT-IR and mechanical properties tests. The surface wettability were studied by contact angle measurement (CA. As a kind of short-term implant biomaterial, the results of the hemolysis and platelet adhesive tests were recorded by spectrophotometer and scanning electron microscopy (SEM, indicating the materials have a great potential for developments and applications in biomedical field.

  16. Synthesis and properties of aqueous polyurethane dispersions: Influence of molecular weight of polyethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Mumtaz, Fatima; Zuber, Mohammad; Zia, Khalid Mahmood [Government College University, Faisalabad (Pakistan); Jamil, Tahir [University of the Punjab, Lahore (Pakistan); Hussain, Rizwan [National Engineering and Scientific Commission (NESCOM), Islamabad (Pakistan)

    2013-12-15

    Aqueous polyurethane dispersions (PUDs) have recently emerged as important alternatives to their solvent-based counterparts for various applications due to increasing health and environmental awareness. A series of aqueous polyurethane dispersions containing carboxylate anion as hydrophilic pendant groups were synthesized through step growth polymerization reaction using hexamethylene diisocyanate (HDI), 1,4-butanediol (1,4-BDO), dimethylol propionic acid (DMPA) and polyethylene glycol (PEG) of different molecular weight. Effect of PEG molecular weight was investigated on molecular structure, contact angle measurement, and physical and adhesive properties of PU emulsions. Fourier transform infrared spectroscopy (FT-IR) was used to check the completion of polymerization reaction. Contact angle measurement indicated that the hydrophilicity of polymer increases by increasing molecular weight of PEG with a corresponding decrease in contact angle. Results of T-peel test showed a decrease in peel strength by increasing molecular weight of PEG. Moreover, solid contents%, drying time and storage stability suggested fast drying properties and greater stability of aqueous PU dispersions.

  17. Manufacturing of biodegradable polyurethane scaffolds based on polycaprolactone using a phase separation method: physical properties and in vitro assay

    Science.gov (United States)

    Asefnejad, Azadeh; Khorasani, Mohammad Taghi; Behnamghader, Aliasghar; Farsadzadeh, Babak; Bonakdar, Shahin

    2011-01-01

    Background Biodegradable polyurethanes have found widespread use in soft tissue engineering due to their suitable mechanical properties and biocompatibility. Methods In this study, polyurethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and a copolymer of 1,4-butanediol as a chain extender. Polyurethane scaffolds were fabricated by a combination of liquid–liquid phase separation and salt leaching techniques. The effect of the NCO:OH ratio on porosity content and pore morphology was investigated. Results Scanning electron micrographs demonstrated that the scaffolds had a regular distribution of interconnected pores, with pore diameters of 50–300 μm, and porosities of 64%–83%. It was observed that, by increasing the NCO:OH ratio, the average pore size, compressive strength, and compressive modulus increased. L929 fibroblast and chondrocytes were cultured on the scaffolds, and all samples exhibited suitable cell attachment and growth, with a high level of biocompatibility. Conclusion These biodegradable polyurethane scaffolds demonstrate potential for soft tissue engineering applications. PMID:22072874

  18. [Analysis of correlation between pulmonary function and expression levels of matrix metalloproteinases-9 and tissue inhibitor of metalloproteinase-1 among toluene diisocyanate exposed workers].

    Science.gov (United States)

    Miao, P P; Meng, T; Jia, Q; Niu, Y; Ye, M; Ji, Y Q; Ju, R; Chen, X L; Shao, H; Zheng, Y X; Dai, Y F

    2016-05-01

    To investigate the effect of occupational toluene diisocyanate(TDI) exposure on matrix metalloproteinases-9 (MMP-9) and tissue inhibitor of metalloproteinase-1(TIMP-1), and analysis of the correlation of MMP-9,TIMP-1,MMP-9/TIMP-1 and lung function. In October 2014, based on cluster sampling, we conducted a cross-sectional study in a TDI production factory located in China's western region. 61 exposed workers were recruited from workers engaged in packing, operating and checking. Based on different levels of the external exposure, the packers were classified as high exposed group, while operators and checkers as low exposed group. 58 factory managers, matching age and agent, were selected as controls, having same work intense and not contacting the TDI or other allergens. The questionnaire surveys were used to obtain the agent, age, work age, smoking and drinking, personal and family allergic history, occupational history, and the recent health conditions. The levels of MMP-9 and TIMP-1 in serum of subjects were determind by ELISA. The time weighted average concentrations (8h-TWA) were used to describe the levels of TDI air exposure in working environment. Spearman correlation assay was used to investigate the correlation of MMP-9, TIMP-1, MMP-9/TIMP-1 and lung function, exposure time. 8-hour TWA means of TDI air levels in exposed group, packers, operators and checkers were 0.39, 0.76, 0.25 mg/m(3), respectively . According to the external exposure concentration, the packers were classified as high exposed group, and the operators and checkers were classified as low exposed group. In controls, low exposed group and high exposed group, the levels of MMP-9, respectively, were (807.21±347.70),(586.91±317.50),(388.94±312.01) ng/ml (χ(2)=16.69, Pcorrelation analysis showed that levels of MMP-9 were positively associated with FEV1.0, and FEV1.0/FVC (r values were 0.27, 0.25, respectively, all Pcorrelated with exposure time(r=-0.26, P=0.040). The positive correlations

  19. Modeling Heat Transfer and Pressurization of Polymeric Methylene Diisocyanate (PMDI) Polyurethane Foam in a Sealed Container.

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Sarah Nicole

    2018-01-01

    Polymer foam encapsulants provide mechanical, electrical, and thermal isolation in engineered systems. It can be advantageous to surround objects of interest, such as electronics, with foams in a hermetically sealed container to protect the electronics from hostile en vironments, such as a crash that produces a fire. However, i n fire environments, gas pressure from thermal decomposition of foams can cause mechanical failure of the sealed system . In this work, a detailed study of thermally decomposing polymeric methylene diisocyanate (PMDI) - polyether - polyol based polyurethane foam in a sealed container is presented . Both experimental and computational work is discussed. Three models of increasing physics fidelity are presented: No Flow, Porous Media, and Porous Media with VLE. Each model us described in detail, compared to experiment , and uncertainty quantification is performed. While the Porous Media with VLE model matches has the best agreement with experiment, it also requires the most computational resources.

  20. Comparison of the rationale used in setting occupational exposure standards for ionizing radiation and hazardous chemical substances

    International Nuclear Information System (INIS)

    Halton, D.M.

    1986-12-01

    Ten chemicals which create significant occupational hazard are reviewed. They are toluene diisocyanate, hydrogen fluoride, n-hexane, carbon disulphide, cadmium, inorganic mercury, cobalt, nitroglycerol, silica and vinyl chloride. Each is discussed under the headings of physiological intake and elimination in humans, characteristics of acute and chronic toxicity, sites of occupational exposure and rationale for limits of such exposure. Since radioactive substances yield ionizing radiation as the common hazard the treatment of the current permissible levels of exposure is somewhat simpler. Having set out industrial standards for exposure to hazardous substances and radionuclides, a detailed comparison is made. Exposure limits to ioninzing radiation are sufficiently low to remove the appearance of directly related injury. It is expected however that low level exposure may have a stochastic effect, that is, there is the possibility of a slightly increased incidence of neoplasms in a large exposed population, but numbers will be too small to be able to attribute any particular case to the exposure. TLVs on the other hand, depending on the particular chemical, may be high enough in the workplace to permit some directly related signs or symptoms in the exposed individual. 244 refs

  1. Assessment of the risk of respiratory sensitization from fragrance allergens released by air fresheners.

    Science.gov (United States)

    ter Burg, Wouter; Bouma, Krista; Schakel, Durk J; Wijnhoven, Susan W P; van Engelen, Jacqueline; van Loveren, Henk; Ezendam, Janine

    2014-04-01

    Consumers using air fresheners are exposed to the emitted ingredients, including fragrances, via the respiratory tract. Several fragrances are known skin sensitizers, but it is unknown whether inhalation exposure to these chemicals can induce respiratory sensitization. Effects on the immune system were assessed by testing a selection of five fragrance allergens in the respiratory local lymph node assay (LLNA). The probability and extent of exposure were assessed by measuring concentrations of the 24 known fragrance allergens in 109 air fresheners. It was shown that the most frequently used fragrances in air fresheners were D-limonene and linalool. In the respiratory LLNA, these fragrances were negative. Of the other tested chemicals, only isoeugenol induced a statistically significant increase in cell proliferation. Consumer exposure was assessed in more detail for D-limonene, linalool, and isoeugenol by using exposure modeling tools. It was shown that the most frequently used fragrances in air fresheners, D-limonene, and linalool gave rise to a higher consumer exposure compared with isoeugenol. To evaluate whether the consumer exposure to these fragrances is low or high, these levels were compared with measured air concentrations of diisocyanates, known human respiratory sensitizers. This comparison showed that consumer exposure from air fresheners to D-limonene, linalool, and isoeugenol is considerably lower than occupational exposure to diisocyanates. By combing this knowledge on sensitizing potency with the much lower exposure compared to diisocyanates it seems highly unlikely that isoeugenol can induce respiratory sensitization in consumers using air fresheners.

  2. Fluorescent determination of poly(hexamethylene guanidine) via the aggregates it forms with quantum dots and magnetic nanoparticles

    International Nuclear Information System (INIS)

    Likhachev, Konstantin V.; Beklemishev, Mikhail K.; Ovcharenko, Elena O.; Dityuk, Alexander I.; Efimov, Konstantin M.; Abramchuk, Sergei S.

    2016-01-01

    The authors report that the cationic polymer-oligomer poly(hexamethylene guanidine) (PHMG) in the form of its hydrochloride induces the formation of mixed aggregates composed of anionic magnetic nanoparticles (magNPs), PHMG and anionic quantum dots (QDs). The magNPs consisted of polymer-coated magnetite nanoparticles, and the QDs consisted of polymer-coated CdSe-CdS/ZnS nanoparticles with an emission maximum at 617 nm. This finding is exploited in a semi-quantitative method for the determination of PHMG. The protocol includes magnetic separation of the mixed aggregates (magNPs/PHMG/QDs) from the sample and excess QDs, redispersion of the aggregates in water, and measurement of fluorescence intensity. The signal is proportional to the concentration of PHMG in the 0.05 to 0.2 mg L"−"1 concentration range, with intra-day RSDs of up to 27 %. The limit of detection (LOD) of PHMG in spiked run-off waters, swimming pool water and wastewater is 23 μg L"−"1. This PHMG assay is selective in that high concentrations of surfactants and inorganic salts are tolerated. Polyethyleneimine and poly(diallyldimethylammonium chloride) also cause the formation of mixed aggregates but only at higher concentrations. Both a fluorometer and a digital camera (using a 365-nm LED as a light source) were used to measure fluorescence. In case of using a digital camera, the LOD is 40 μg L"−"1 and the intraday RSDs are up to 23 %. The method is sensitive, fairly selective and rather simple. (author)

  3. Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

    Energy Technology Data Exchange (ETDEWEB)

    Mortley, Aba [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, P.O. Box 17000, Stn Forces, Kingston, ON, K7K 7B4 (Canada)], E-mail: aba.mortley@rmc.ca; Bonin, H.W.; Bui, V.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, P.O. Box 17000, Stn Forces, Kingston, ON, K7K 7B4 (Canada)

    2007-12-15

    Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging {sup 13}C solid state NMR spectra imply limited sample degradation with increasing radiation.

  4. Polyurethane/fluor-hydroxyapatite nanocomposite scaffolds for bone tissue engineering. Part I: morphological, physical, and mechanical characterization

    Science.gov (United States)

    Asefnejad, Azadeh; Behnamghader, Aliasghar; Khorasani, Mohammad Taghi; Farsadzadeh, Babak

    2011-01-01

    In this study, new nano-fluor-hydroxyapatite (nFHA)/polyurethane composite scaffolds were fabricated for potential use in bone tissue engineering. Polyester urethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and 1,4-butanediol as chain extender. Nano fluor-hydroxyapatite (nFHA) was successfully synthesized by sol-gel method. The solid–liquid phase separation and solvent sublimation methods were used for preparation of the porous composites. Mechanical properties, chemical structure, and morphological characteristics of the samples were investigated by compressive test, Fourier transform infrared, and scanning electron microscopy (SEM) techniques, respectively. The effect of nFHA powder content on porosity and pore morphology was investigated. SEM images demonstrated that the scaffolds were constituted of interconnected and homogeneously distributed pores. The pore size of the scaffolds was in the range 50–250 μm. The result obtained in this research revealed that the porosity and pore average size decreased and compressive modulus increased with nFHA percentage. Considering morphological, physical, and mechanical properties, the scaffold with a higher ratio of nFHA has suitable potential use in tissue regeneration. PMID:21289986

  5. Shape memory polymers based on uniform aliphatic urethane networks

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, T S; Bearinger, J P; Herberg, J L; Marion III, J E; Wright, W J; Evans, C L; Maitland, D J

    2007-01-19

    Aliphatic urethane polymers have been synthesized and characterized, using monomers with high molecular symmetry, in order to form amorphous networks with very uniform supermolecular structures which can be used as photo-thermally actuable shape memory polymers (SMPs). The monomers used include hexamethylene diisocyanate (HDI), trimethylhexamethylenediamine (TMHDI), N,N,N{prime},N{prime}-tetrakis(hydroxypropyl)ethylenediamine (HPED), triethanolamine (TEA), and 1,3-butanediol (BD). The new polymers were characterized by solvent extraction, NMR, XPS, UV/VIS, DSC, DMTA, and tensile testing. The resulting polymers were found to be single phase amorphous networks with very high gel fraction, excellent optical clarity, and extremely sharp single glass transitions in the range of 34 to 153 C. Thermomechanical testing of these materials confirms their excellent shape memory behavior, high recovery force, and low mechanical hysteresis (especially on multiple cycles), effectively behaving as ideal elastomers above T{sub g}. We believe these materials represent a new and potentially important class of SMPs, and should be especially useful in applications such as biomedical microdevices.

  6. Investigating the use of coupling agents to improve the interfacial properties between a resorbable phosphate glass and polylactic acid matrix.

    Science.gov (United States)

    Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew J; Rudd, Chris D; Walker, Gavin S; Scotchford, Colin A

    2013-09-01

    Eight different chemicals were investigated as potential candidate coupling agents for phosphate glass fibre reinforced polylactic acid composites. Evidence of reaction of the coupling agents with phosphate glass and their effect on surface wettability and glass degradation were studied along with their principle role of improving the interface between glass reinforcement and polymer matrix. It was found that, with an optimal amount of coupling agent on the surface of the glass/polymer, interfacial shear strength improved by a factor of 5. Evidence of covalent bonding between agent and glass was found for three of the coupling agents investigated, namely: 3-aminopropyltriethoxysilane; etidronic acid and hexamethylene diisocyanate. These three coupling agents also improved the interfacial shear strength and increased the hydrophobicity of the glass surface. It is expected that this would provide an improvement in the macroscopic properties of full-scale composites fabricated from the same materials which may also help to retain these properties for the desired length of time by retarding the breakdown of the fibre/matrix interface within these composites.

  7. Polycarbonate-based polyurethane as a polymer electrolyte matrix for all-solid-state lithium batteries

    Science.gov (United States)

    Bao, Junjie; Shi, Gaojian; Tao, Can; Wang, Chao; Zhu, Chen; Cheng, Liang; Qian, Gang; Chen, Chunhua

    2018-06-01

    Four kinds of polycarbonate-based polyurethane with 8-14 wt% hard segments content are synthesized via reactions of polycarbonatediol, hexamethylene diisocyanate and diethylene glycol. The mechanical strength of the polyurethanes increase with the increase of hard segments content. Solid polymer electrolytes composed of the polycarbonate-based polyurethanes and LiTFSI exhibits fascinating characteristics for all-solid-state lithium batteries with a high ionic conductivity of 1.12 × 10-4 S cm-1 at 80 °C, an electrochemical stability window up to 4.5 V (vs. Li+/Li), excellent mechanical strength and superior interfacial stability against lithium metal. The all-solid-state batteries using LiFePO4 cathode can deliver high discharge capacities (161, 158, 134 and 93 mAh g-1 at varied rates of 0.2, 0.5, 1 and 2 C) at 80 °C and excellent cycling performance (with 91% capacity retention after 600 cycles at 1 C). All the results indicate that such a polyurethane-based solid polymer electrolyte can be a promising candidate for all-solid-state lithium batteries.

  8. Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

    International Nuclear Information System (INIS)

    Mortley, Aba; Bonin, H.W.; Bui, V.T.

    2007-01-01

    Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging 13 C solid state NMR spectra imply limited sample degradation with increasing radiation

  9. A water-soluble, mucoadhesive quaternary ammonium chitosan-methyl-β-cyclodextrin conjugate forming inclusion complexes with dexamethasone.

    Science.gov (United States)

    Piras, Anna Maria; Zambito, Ylenia; Burgalassi, Susi; Monti, Daniela; Tampucci, Silvia; Terreni, Eleonora; Fabiano, Angela; Balzano, Federica; Uccello-Barretta, Gloria; Chetoni, Patrizia

    2018-03-30

    The ocular bioavailability of lipophilic drugs, such as dexamethasone, depends on both drug water solubility and mucoadhesion/permeation. Cyclodextrins and chitosan are frequently employed to either improve drug solubility or prolong drug contact onto mucosae, respectively. Although the covalent conjugation of cyclodextrin and chitosan brings to mucoadhesive drug complexes, their water solubility is restricted to acidic pHs. This paper describes a straightforward grafting of methyl-β-cyclodextrin (MCD) on quaternary ammonium chitosan (QA-Ch60), mediated by hexamethylene diisocyanate. The resulting product is a water-soluble chitosan derivative, having a 10-atom long spacer between the quaternized chitosan and the cyclodextrin. The derivative is capable of complexing the model drug dexamethasone and stable complexes were also observed for the lyophilized products. Furthermore, the conjugate preserves the mucoadhesive properties typical of quaternized chitosan and its safety as solubilizing excipient for ophthalmic applications was preliminary assessed by in vitro cytotoxicity evaluations. Taken as a whole, the observed features appear promising for future processing of the developed product into 3D solid forms, such as controlled drug delivery systems, films or drug eluting medical devices.

  10. Modification of an Amposta origin bitumen by using tlie Friedel and Crafts reaction with toluyiene-2,4-diisocyanate

    Directory of Open Access Journals (Sweden)

    Blanco, M.

    1988-03-01

    Full Text Available In this works, we have modified a bitumen from Amposta by using the Friedel and Crafts reaction with toluylene-2,4-diisocyanate in presence of aluminium trichloride, presenting as well as the characteristics of the original bitumen as the ones of the modification products. We have made technological test, aging of thin film, rheological test, thermical susceptibility and components analyses.

    En el presente trabajo se ha modificado un betún procedente de Amposta por reacción de Friedei y Crafts con 4-metil-1,3-bencenodiisocianato, en presencia de tricloruro de aluminio. Se han determinado las características del betún original así como las de los productos obtenidos en la modificación. Se han llevado a cabo ensayos de tipo tecnológico, envejecimiento en película delgada, propiedades reológicas, susceptibilidad térmica y análisis de componentes.

  11. Surface modification of calcined kaolin with toluene diisocyanate based on high energy ball milling

    International Nuclear Information System (INIS)

    Yuan, Yongbing; Chen, Hongling; Lin, Jinbin; Ji, Yan

    2013-01-01

    The surface of calcined kaolin particle was modified with toluene diisocyanate (TDI) by using high energy ball milling. The prepared hybrids were characterized by FT-IR, MAS NMR, thermal analysis (TGA-DSC), static water contact angle (CA), apparent viscosity and transmission electron microscopy (TEM). FT-IR and MAS NMR spectra demonstrated that TDI molecules were chemically anchored to kaolin surface after modification. The results of thermal analysis showed that the maximum grafting ratio reached up to 446.61% when the mass ratio of TDI/kaolin was 0.5:1.0, and CA measurements revealed that the resultant hybrids exhibited strong hydrophobicity (148.82°). Apparent viscosity and TEM were employed to examine the dispersion properties of blank and modified kaolin particles in poly (dimenthylsiloxane) matrix. The results illustrated that the dispersion stability depended strongly on the grafting ratio of TDI, neither too low nor too high achieved uniform and stable dispersion, and the favorable grafting ratio was obtained when the mass ratio of TDI/kaolin was 0.2:1.0. Further modification of TDI/kaolin (mass ration of TDI/kaolin, 1.0:1.0) particles with bis(aminopropyl)-terminated-poly(dimethylsiloxane) (APS) was also investigated. TEM evidenced that the dispersion properties of the obtained TDI/APS/kaolin particles were remarkably improved in octamethyl cyclotetrasiloxane compared with the original TDI/kaolin particles.

  12. Surface modification of calcined kaolin with toluene diisocyanate based on high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yongbing; Chen, Hongling, E-mail: hlchen@njut.edu.cn; Lin, Jinbin; Ji, Yan

    2013-11-01

    The surface of calcined kaolin particle was modified with toluene diisocyanate (TDI) by using high energy ball milling. The prepared hybrids were characterized by FT-IR, MAS NMR, thermal analysis (TGA-DSC), static water contact angle (CA), apparent viscosity and transmission electron microscopy (TEM). FT-IR and MAS NMR spectra demonstrated that TDI molecules were chemically anchored to kaolin surface after modification. The results of thermal analysis showed that the maximum grafting ratio reached up to 446.61% when the mass ratio of TDI/kaolin was 0.5:1.0, and CA measurements revealed that the resultant hybrids exhibited strong hydrophobicity (148.82°). Apparent viscosity and TEM were employed to examine the dispersion properties of blank and modified kaolin particles in poly (dimenthylsiloxane) matrix. The results illustrated that the dispersion stability depended strongly on the grafting ratio of TDI, neither too low nor too high achieved uniform and stable dispersion, and the favorable grafting ratio was obtained when the mass ratio of TDI/kaolin was 0.2:1.0. Further modification of TDI/kaolin (mass ration of TDI/kaolin, 1.0:1.0) particles with bis(aminopropyl)-terminated-poly(dimethylsiloxane) (APS) was also investigated. TEM evidenced that the dispersion properties of the obtained TDI/APS/kaolin particles were remarkably improved in octamethyl cyclotetrasiloxane compared with the original TDI/kaolin particles.

  13. Síntesis y caracterización de adhesivos reposicionables de poliuretano dispersos en agua, obtenidos a partir de aceite de castor maleinizado Synthesis and characterization of pressure-sensitive adhesives of waterborne polyurethane from maleinizated castor oil

    Directory of Open Access Journals (Sweden)

    Paula Mazo

    2010-06-01

    Full Text Available El presente trabajo se centró en la producción de dispersiones acuosas de poliuretano empleando el método de emulsificación por inversión de fases. Para la síntesis fueron empleados dos polioles: uno comercial tipo poliéster y el otro es aceite de castor maleinizado (MACO; dos diisocianatos, uno aromático Toluen diisocianato (TDI y otro alifático Hexametilen diisocianato (HDI, siendo poco comunes para esta aplicación. Como emulsificante interno se empleó ácido cítrico el cual es muy económico y de fácil adquisición. Como factores se evaluaron la cantidad de ácido cítrico y la relación molar de grupos isocianato a hidroxilos (NCO/OH, generando un diseño de experimentos factorial 3² y minimizando el contenido de sólidos sedimentados. Mediante la metodología de superficie de respuesta, se obtuvo una ecuación polinomial cuadrática por un análisis de regresión múltiple. Los poliuretanos formados fueron evaluados en cuanto a sus propiedades adhesivas y mecánicas (pegajosidad tack, pegajosidad en cinta loop tack, cohesión hold, pelado peel, lo que permitió clasificar el adhesivo como reposicionable, para emplearlo en etiquetas.This work focused on the production of aqueous dispersions of polyurethane using the emulsification method by phase inversion. For the synthesis two polyols were employed, viz. a commercial polyester and Maleinizated Castor Oil (MACO, with two diisocyanates: one aromatic, toluene diisocyanate (TDI and another aliphatic, hexamethylene diisocyanate (HDI, which are not common for this application. Citric acid was used as internal emulsifier which is inexpensive and readily available. The parameters were the amount of citric acid and the mole ratio of isocyanate groups to hydroxyl (NCO/OH, generating a 3² factorial design, with minimization of the sedimented solids. The surface methodology was used to obtain a quadratic polynomial equation by multiple regression analysis. Polyurethanes synthesized were

  14. The influence of hard segment content on mechanical and thermal properties of polycarbonate-based polyurethane materials

    Directory of Open Access Journals (Sweden)

    Budinski-Simendić Jaroslava

    2012-01-01

    Full Text Available Aliphatic segmented polyurethanes were prepared by one-step procedure in catalytic reaction between polycarbonate diol, hexamethylene-diisocyanate and 1,4-butandiol (as chain extender. The hard segment content TS was varied (17, 24, 30 and 42 wt. % by changing the ratio of starting compounds. The soft segment is made from flexible aliphatic polycarbonate diol, while hard segments consist of chain extender and diisocyanate component. In order to study the hydrogen bonding formation and phase separation, Fourier transform infrared spectroscopy (FT-IR was used. Wide angle X-ray scattering (WAXS was performed to determine a degree of crystallinity and to investigate the phase behavior of prepared elastomers. The effect of TS content on mechanical properties (tensile strength, elongation at break and hardness was tested. Thermal behavior of prepared novel polycarbonate-based polyurethanes was investigated using differential scanning callorimetry (DSC. It was determined that the elastomer which contains the highest amount of urethane groups in its structure (TS content of 42 wt. % exhibits the most pronounced phase separation and the highest degree of crystallinity. All prepared polyurethanes exhibit high elongation at break (over 700%. The glass transition temperature Tg of prepared samples was in the temperature region from −39 to −36°C, and it was found to be slightly influenced by the soft segment content. The enthalpy of chain segments relaxation in diffused region between hard and soft domains (detected in the temperature range from 35 to 55 °C was decreased with the increase of hard segment content. The multiple melting of hard segments (connected with the dissruption of physical crosslinks appeared above 100 °C. It was found that the melting enthalpy linearly increases with the increase of urethane group content. Sample with 42 wt. % of TS has the highest value of melting enthalpy (41.5 J/g.

  15. Fe-Ni Nanoparticles supported on carbon nanotube-co-cyclodextrin polyurethanes for the removal of trichloroethylene in water

    Energy Technology Data Exchange (ETDEWEB)

    Krause, Rui W. M., E-mail: rkrause@uj.ac.za; Mamba, Bhekie B.; Dlamini, Langelihle N.; Durbach, Shane H. [University of Johannesburg, Department of Chemical Technology (South Africa)

    2010-02-15

    Nanoscale bimetallic particles of nickel on iron were supported on carbon nanotubes and then co-polymerized with {beta}-cyclodextrin (CNTs/CD) and the resulting polymers applied to the degradation of pollutants in water. The bimetallic nanoparticles (BMNPs) were first embedded on functionalized carbon nanotubes (f-CNTs) before being copolymerized with beta cyclodextrin ({beta}-CD) and hexamethylene diisocyanate (HMDI) forming a water-insoluble polyurethane. The particle size and distribution of BMNPs were determined by Transmission Electron Microscopy (TEM), and the surface area was determined by using the Brunauer-Emmett-Teller (BET) method. Energy dispersive X-ray spectroscopy (EDXS) was used to confirm the formation of the BMNPs. Degradation of trichloroethylene (TCE) as a model pollutant was studied and more than 98% reduction in TCE was achieved by the polymers. Polymers with the BMNPs maintained their efficiency in degrading TCE after several cycles compared to metal-free polymers. The degradation was monitored by using gas chromatography-mass spectrometry (GC-MS), while the production of chlorides was verified by using ion chromatography (IC). Atomic absorption spectroscopy (AAS) was employed to determine the possible leaching of the BMNPs from the polymer, and confirmed to be extremely low.

  16. N-halamine-based rechargeable antimicrobial and biofilm-controlling polyurethane

    Science.gov (United States)

    Sun, Xinbo; Cao, Zhengbing; Porteous, Nuala; Sun, Yuyu

    2012-01-01

    An N-halamine precursor, 5, 5-dimethyl hydantoin (DMH), was covalently linked to the surface of polyurethane (PU) with 1,6-hexamethylene diisocyanate (HDI) as a coupling agent. The reaction pathways were investigated using propyl isocyanate (PI) as a model compound, and the results suggested that the imide and amide groups of DMH had very similar reactivity toward the isocyanate groups on PU surfaces activated with HDI. After bleach treatment, the covalently bound DMH moieties were transformed into N-halamines. The new N-halmaine-based PU provided potent antimicrobial effects against Staphylococcus aureus (S. aureus, Gram-positive), Escherichia coli (E. coli, Gram-negative), methicillin-resistant staphylococcus aureus (MRSA, drug resistant Gram-positive bacteria), vancomycin-resistant enterococcus (VRE, drug resistant Gram-positive bacteria), and Candida albicans (C. ablicans, fungi), and successfully prevented bacterial and fungal biofilm formation. The antimicrobial and biofilm-controlling effects were stable for longer than 6 months under normal storage in open air. Furthermore, if the functions were lost due to prolonged use, they could be recharged by another chlorination treatment. The recharging could be repeated as needed to achieve long-term protection against microbial contamination and biofilm-formation. PMID:22244984

  17. Influence of Hard Segments on the Thermal, Phase-Separated Morphology, Mechanical, and Biological Properties of Polycarbonate Urethanes

    Directory of Open Access Journals (Sweden)

    Rong Zhu

    2017-03-01

    Full Text Available Abstract: In this study, we have fabricated a series of polycarbonate polyurethanes using a two-step bulk reaction by the melting pre-polymer solution-casting method in order to synthesize biomedical polyurethane elastomers with good mechanical behavior and biostability. The polyurethanes were prepared using dibutyltin dilaurate as the catalyst, poly(1,6-hexanediolcarbonate microdiols (PCDL as the soft segment, and the chain extender 1,4-butanediol (BDO and aliphatic 1,6-hexamethylene diisocyanate (HDI as the hard segments. The chemical structures and physical properties of the obtained films were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR spectroscopy, gel permeation chromatography (GPC, differential scanning calorimeter (DSC, and mechanical property tests. The surface properties and degrees of microphase separation were further analyzed by water droplet contact angle measurements (CA and atomic force microscopy (AFM. The materials exhibited a moderate toxic effect on the tetrazolium (MTT assay and good hemocompatibility through hemolytic tests, indicating a good biocompatibility of the fabricated membranes. The materials could be considered as potential and beneficial suitable materials for tissue engineering, especially in the fields of artificial blood-contacting implants or other biomedical applications.

  18. Fe-Ni Nanoparticles supported on carbon nanotube-co-cyclodextrin polyurethanes for the removal of trichloroethylene in water

    International Nuclear Information System (INIS)

    Krause, Rui W. M.; Mamba, Bhekie B.; Dlamini, Langelihle N.; Durbach, Shane H.

    2010-01-01

    Nanoscale bimetallic particles of nickel on iron were supported on carbon nanotubes and then co-polymerized with β-cyclodextrin (CNTs/CD) and the resulting polymers applied to the degradation of pollutants in water. The bimetallic nanoparticles (BMNPs) were first embedded on functionalized carbon nanotubes (f-CNTs) before being copolymerized with beta cyclodextrin (β-CD) and hexamethylene diisocyanate (HMDI) forming a water-insoluble polyurethane. The particle size and distribution of BMNPs were determined by Transmission Electron Microscopy (TEM), and the surface area was determined by using the Brunauer-Emmett-Teller (BET) method. Energy dispersive X-ray spectroscopy (EDXS) was used to confirm the formation of the BMNPs. Degradation of trichloroethylene (TCE) as a model pollutant was studied and more than 98% reduction in TCE was achieved by the polymers. Polymers with the BMNPs maintained their efficiency in degrading TCE after several cycles compared to metal-free polymers. The degradation was monitored by using gas chromatography-mass spectrometry (GC-MS), while the production of chlorides was verified by using ion chromatography (IC). Atomic absorption spectroscopy (AAS) was employed to determine the possible leaching of the BMNPs from the polymer, and confirmed to be extremely low.

  19. RX-08-HD, a low-viscosity, injection-moldable explosive for filling tortuous paths

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.M.; Jessop, E.S.; Swansiger, R.W.

    1997-10-01

    Cast cure, extrusion cast, and paste extrudable explosives have not been designed for transferring through long tortuous paths or into fine three dimensional shapes. To allow the crystalline explosive to flow a lubricating fluid is required. The energetic liquid ethane trinitrate (TMETN) was used as the lubricant to maximize the explosive energy. TMETN is a liquid nitrate ester which requires stabilization with conventional free radical stabilizers such as 2- nitrodiphenylamine, methyl-nitroanaline, or ethyl centrylite. Since these injection moldable explosives are expected to cure in place, a polyesterurethane binder based on polymeric isocyanate of hexamethylene diisocyanate and polycaprolactone polyols is dissolved in TMETN. The solubility of the polymer precursors in TMETN also reduces the energetic liquids sensitivity. The latent cure catalyst Dabco T-131 was used to minimize shrinkage associated with thermal expansion, reduce cost associated with oven cures, to give 4-6 hour potlife and overnight cure to handling strength. The product RX-08-HD is a new, low-viscosity, injection moldable explosive that can be extruded into complex, void-free shapes. Combined with appropriate design and other aspects of weaponization, RX-08-HD has produced outstanding results.

  20. Carboxylated Polyurethanes Containing Hyperbranched Polyester Soft Segments

    Directory of Open Access Journals (Sweden)

    Žigon, M.

    2006-09-01

    Full Text Available hyperbranched polyester soft segments (HB PU with functional carboxylic groups in order to enable the preparation of stable HB PU dispersions. Carboxylated hyperbranched polyurethanes were synthesized using a hyperbranched polyester based on 2,2-bis(methylolpropionic acid of the fourth pseudo-generation (Boltorn H40 and hexamethylene (HDI or isophorone diisocyanate (IPDI. The reactivity of hyperbranched polyester with HDI was lower than expected, possibly due to the presence of less reactive hydroxyl groups in the linear repeat units. A gel was formed at mole ratios rNCO/OH = 1:2 or 1:4. The synthesis of HB PU was performed with partly esterified hyperbranched polyester with lowered hydroxyl functionality. The carboxyl groups were incorporated in the HB PU backbone by reaction of residual hydroxyl groups with cis-1,2-cyclohexanedicarboxylic anhydride. HB PU aqueous dispersions were stable at least for two months, although their films were brittle. The tensile strength and Young's modulus of blends of linear and HB PU decreased with increasing content of HB PU whereas elongation at break remained nearly constant, which was explained in terms of looser chain packing due to more open tree-like hyperbranched structures.

  1. Isocyanate-functionalized chitin and chitosan as gelling agents of castor oil.

    Science.gov (United States)

    Gallego, Rocío; Arteaga, Jesús F; Valencia, Concepción; Franco, José M

    2013-06-03

    The main objective of this work was the incorporation of reactive isocyanate groups into chitin and chitosan in order to effectively use the products as reactive thickening agents in castor oil. The resulting gel-like dispersions could be potentially used as biodegradable lubricating greases. Three different NCO-functionalized polymers were obtained: two of them by promoting the reaction of chitosan with 1,6-hexamethylene diisocyanate (HMDI), and the other by using chitin instead of chitosan. These polymers were characterized through 1H-NMR, FTIR and thermogravimetric analysis (TGA). Thermal and rheological behaviours of the oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA and small-amplitude oscillatory shear (SAOS) measurements. The evolution and values of the linear viscoelasticity functions with frequency for -NCO-functionalized chitosan- and chitin-based oleogels are quite similar to those found for standard lubricating greases. In relation to long-term stability of these oleogels, no phase separation was observed and the values of viscoelastic functions increase significantly during the first seven days of ageing, and then remain almost constant. TGA analysis showed that the degradation temperature of the resulting oleogels is higher than that found for traditional lubricating greases.

  2. Comparison of the concepts used to develop and apply occupational exposure limits for ionizing radiation and hazardous chemical substances

    International Nuclear Information System (INIS)

    Halton, D.M.

    1988-01-01

    The rationales used by the American Conference of Governmental Industrial Hygienists (AC-GIH) to recommend exposure limits for 10 chemicals were reviewed. The 10 chemicals chosen were known to produce chronic disease after prolonged overexposure in the workplace. The chemicals were toluene diisocyanate, hydrogen fluoride, n-hexane, carbon disulfide, cadmium, inorganic mercury, cobalt, nitroglycerol, silica, and vinyl chloride. The rationales used by the International Commission on Radiological Protection (ICRP) to recommend limits for workplace exposure to ionizing radiation were reviewed. The rationales used in occupational health by ACGIH were then compared with those used by ICRP in health physics. The comparison revealed a significant divergence in the underlying concepts and philosophies of the two approaches. This divergence cannot be solely attributed to differences in scientific knowledge about toxicological and radiological effects. In areas of scientific uncertainty, exposure limits for ionizing radiation are based on worst case or conservative assumptions. This approach favors human safety. Parallel approaches could not be found for any of the 10 chemicals reviewed. Other factors such as the costs incurred by industry in meeting the proposed standards played a more significant role in establishing limits for workplace chemicals than for ionizing radiation

  3. MALDI MS-based Composition Analysis of the Polymerization Reaction of Toluene Diisocyanate (TDI) and Ethylene Glycol (EG).

    Science.gov (United States)

    Ahn, Yeong Hee; Lee, Yeon Jung; Kim, Sung Ho

    2015-01-01

    This study describes an MS-based analysis method for monitoring changes in polymer composition during the polyaddition polymerization reaction of toluene diisocyanate (TDI) and ethylene glycol (EG). The polymerization was monitored as a function of reaction time using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS). The resulting series of polymer adducts terminated with various end-functional groups were precisely identified and the relative compositions of those series were estimated. A new MALDI MS data interpretation method was developed, consisting of a peak-resolving algorithm for overlapping peaks in MALDI MS spectra, a retrosynthetic analysis for the generation of reduced unit mass peaks, and a Gaussian fit-based selection of the most prominent polymer series among the reconstructed unit mass peaks. This method of data interpretation avoids errors originating from side reactions due to the presence of trace water in the reaction mixture or MALDI analysis. Quantitative changes in the relative compositions of the resulting polymer products were monitored as a function of reaction time. These results demonstrate that the mass data interpretation method described herein can be a powerful tool for estimating quantitative changes in the compositions of polymer products arising during a polymerization reaction.

  4. Development of test systems for characterizing emissions from spray polyurethane foam insulation (SPFI)

    Science.gov (United States)

    The relationship between onsite manufacture of spray polyurethane foam insulation (SPFI) and potential exposures to diisocyanates, amines, flame retardants (FRs), blowing agents, aldehydes and other organic compounds that may be emitted from SPFI is not well understood. EPA is de...

  5. Glutathione-mediated biodegradable polyurethanes derived from L-arabinitol.

    Science.gov (United States)

    de Paz, M Violante; Zamora, Francisca; Begines, Belén; Ferris, Cristina; Galbis, Juan A

    2010-01-11

    The synthesis, characterization, and some properties of new glutathione-mediated biodegradable sugar-based copolyurethanes are described. These copolyurethanes were obtained by polyaddition reaction of mixtures of 2,2'-dithiodiethanol (DiT) and 2,3,4-tri-O-benzyl-L-arabinitol (ArBn) or 2,3,4-tri-O-methyl-L-arabinitol (ArMe) to 1,6-hexamethylene diisocyanate (HMDI). The copolymer compositions were studied by elemental microanalyses and (1)H NMR, revealing that the content of the copolymer units is in all cases very similar to that of their corresponding feed. The PU(DiT-HMDI) homopolymer exhibited a high crystallinity, but the introduction of the arabinitol-based diols led to a reduction in the crystallinity of the copolymers. In their TG curves, the copolymers exhibited a mixed trend of the related homopolymers, and all of them were thermally stable, with degradation temperatures above 220 degrees C. The degradation properties of the macromolecules under physiological conditions in the presence of glutathione were tested. All the copolyurethanes proved to be biodegradable under the experimental conditions (pH = 7.02 and 37 degrees C). The degradation pattern of the copolymers depended not only on the dithiodiethanol (DiT) reactive units ratio in the polymer backbone, but also on the crystallinity of the macromolecule.

  6. Synthesis and Characterization of Polycaprolactone-Based Polyurethanes for the Fabrication of Elastic Guided Bone Regeneration Membrane

    Directory of Open Access Journals (Sweden)

    Shyh-Yuan Lee

    2018-01-01

    Full Text Available The aim of this research is to synthesize polycaprolactone-based polyurethanes (PCL-based PUs that can be further used for the fabrication of guided bone regeneration (GBR membranes with higher tensile strength and elongation at break than collagen and PTFE membranes. The PCL-based PUs were prepared by the polymerization of polycaprolactone (PCL diol with 1,6-hexamethylene diisocyanate (HDI at different ratios using either polyethylene glycol (PEG or ethylenediamine (EDA as chain extenders. The chemical, mechanical, and thermal properties of the synthesized polymers were determined using NMR, FTIR, GPC, DSC, and tensile tester. The PCL and polyurethanes were fabricated as nanofiber membranes by electrospinning, and their mechanical properties and SEM morphology were also investigated. In vitro tests, including WST-1 assay, SEM of cells, and phalloidin cytoskeleton staining, were also performed. It was shown that electrospun membranes made of PCL and PCL-HDI-PEG (2 : 3 : 1 possessed tensile strength of 19.84 MPa and 11.72 MPa and elongation at break of 627% and 362%, respectively. These numbers are equivalent or higher than most of the commercially available collagen and PTFE membrane. As a result, these membranes may have potential for future GBR applications.

  7. Mass spectrometric identification of isocyanate-induced modifications of keratins in human skin

    NARCIS (Netherlands)

    Hulst, A.G.; Verstappen, D.R.W.; Riet-van Oeveren, D. van der; Vermeulen, N.P.E.; Noort, D.

    2015-01-01

    In the current paper we show that exposure of human callus to isocyanates leads to covalent modifications within keratin proteins. Mass spectrometric analyses of pronase digests of keratin isolated from exposed callus show that both mono- and di-adducts (for di-isocyanates) are predominantly formed

  8. Asthma Symptoms and Specific IgE Levels among Toluene Diisocyanate (TDI) Exposed Workers in Tehran, Iran.

    Science.gov (United States)

    Sharifi, Laleh; Karimi, Akram; Shokouhi Shoormasti, Raheleh; Miri, Sara; Heydar Nazhad, Hassan; Bokaie, Saied; Fazlollahi, Mohammad Reza; Sadeghniiat Haghighi, Khosro; Pourpak, Zahra; Moin, Mostafa

    2013-01-01

    Toluene diisocyanate (TDI) is an imperative chemical substance used in the production of polyurethane foams, elastomers, paints and coatings that cause a variety of health problems in workers who are exposed in work places. This study aimed to determine the asthma symptoms and serum specific IgE levels in TDI exposed workers and comparing the results with healthy control group. All the plants that use TDI in the manufacturing of paint and glue in the west of Tehran Province entered to the study and all the workers (550) completed modified initial questionnaire of the NIOSH, the questions were consisted of asthma symptoms. For each symptomatic exposed worker one healthy, sex and age matched control selected. Total IgE and Specific TDI IgE tests were done for each case and control groups. Among 550 TDI exposed workers, 26(4.7%) had asthma symptoms. Nine (34.6%) of symptomatic workers who were exposed to TDI were active cigarette consumer versus 3(11.5%) unexposed workers, P=0.049(CI= 0.953-17.29) OR=4.059. Nine (34.6%) workers had positive family history of atopy versus 1(3.8%) unexposed workers, P=0.0138 (CI= 1.45-305.41) OR=13.24. TDI specific IgE was found in 2 TDI exposed workers and 1 unexposed worker (P=0.5). Mean of total IgE was 339.05 in exposed workers (P=0.201). This study provides clinical and paraclinical data of workers exposed to TDI and points to a relation between atopy and smoking habit with asthma symptoms that offer preventing recommendations for TDI exposed workers and their heath administrators.

  9. Synthesis and luminescent properties of a novel green-emitting Tb (Ⅲ) complex based on amino-modified fluorine silicone oil and isophorone diisocyanate

    Science.gov (United States)

    Hao, Haixia; Chu, Yang; Yu, Zhenjiang; Xie, Hongde; Seo, Hyo Jin

    2017-10-01

    The novel luminescent polymer-rare earth complexes, denoted as (PFSi-IPDI)-Tb(Ⅲ)-Phen, have been successfully synthesized and can be made into flexible films. Amino-modified fluorine silicone oil-isophorone diisocyanate (PFSi-IPDI) was used as the host macromolecular ligand, and 1, 10-Phenanthroline (Phen) as the secondary small-molecular co-ligand. The luminescent lanthanide complexes were characterized by fourier transform infrared (FITR), scanning electron microscope (SEM), thermogravimetric analysis (TGA). The luminescent properties were investigated through photoluminescence excitation (PLE) and emission (PL) spectroscopy. FTIR analysis verifies the successful preparation and integration of PFSi-IPDI to Tb3+. The comparatively uniform morphological structure can be observed in the images of SEM. The polymer-rare earth complexes display the typical luminescence emission peaks under the excitation wavelength of 330 nm. From the decay curve, the short lifetime (about 0.89 ms) is observed for (PFSi-IPDI)-Tb(Ⅲ)-Phen (0.6 mol/L). Moreover, these luminescent polymer-rare earth complexes possess superior thermal stability (T5 > 195 °C). All the interesting results suggest the potential application of the luminescent polymer-rare earth complexes in green-emitting luminescent materials under high temperature.

  10. Compatibility study of trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD) with some energetic components and inert materials

    International Nuclear Information System (INIS)

    Yan Qilong; Li Xiaojiang; Zhang Laying; Li Jizhen; Li Hongli; Liu Ziru

    2008-01-01

    The compatibility of trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD) with some energetic components and inert materials of solid propellants was studied by using the pressure DSC method where, cyclotetramethylenetetranitroamine (HMX), cyclotrimethylenetrinitramine (RDX), 1,4-dinitropiperazine (DNP), 1.25/1-NC/NG mixture, lead 3-nitro-1,2,4-triazol-5-onate (NTO-Pb), aluminum powder (Al, particle size = 13.6 μm) and N-nitrodihydroxyethylaminedinitrate (DINA) were used as energetic components and polyethylene glycol (PEG), polyoxytetramethylene-co-oxyethylene (PET), addition product of hexamethylene diisocyanate and water (N-100), 2-nitrodianiline (2-NDPA), 1,3-dimethyl-1,3-diphenyl urea (C 2 ), carbon black (C.B.), aluminum oxide (Al 2 O 3 ), cupric 2,4-dihydroxy-benzoate (β-Cu), cupric adipate (AD-Cu) and lead phthalate (φ-Pb) were used as inert materials. It was concluded that the binary systems of TNAD with NTO-Pb, RDX, PET and Al powder are compatible, and systems of TNAD with DINA and HMX are slightly sensitive, and with 2-NDPA, φ-Pb, β-Cu, AD-Cu and Al 2 O 3 are sensitive, and with PEG, N-100, C 2 and C.B. are incompatible. The impact and friction sensitivity data of the TNAD and TNAD in combination with the other energetic materials under present study was also obtained, and there was no consequential affiliation between sensitivity and compatibility

  11. Cyclodextrin conjugated magnetic colloidal nanoparticles as a nanocarrier for targeted anticancer drug delivery

    International Nuclear Information System (INIS)

    Banerjee, Shashwat S; Chen, D.-H.

    2008-01-01

    A novel magnetic nanocarrier (CD-GAMNPs) was fabricated for targeted anticancer drug delivery by grafting cyclodextrin (CD) onto gum arabic modified magnetic nanoparticles (GAMNPs) using hexamethylene diisocyanate (HMDI) as a linker. Analyses by transmission electron microscopy (TEM) and dynamic light scattering (DLS) revealed that the product had a mean diameter of 17.1 nm and a mean hydrodynamic diameter of 44.1 nm. The CD grafting was confirmed by Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) indicated that the amount of CD grafted on the GAMNPs was 16.8 mg g -1 . The study on the loading of anticancer drug all-trans-retinoic acid (retinoic acid) revealed that the newly fabricated magnetic nanocarrier possessed a considerably higher adsorption capability as compared to GAMNPs due to the special hydrophobic cavity structure of CD, which could act as a host-guest complex with retinoic acid. Furthermore, it was found that the complexation of CD-GAMNPs with retinoic acid was exothermic and the presence of a surfactant (sodium dodecyl sulfate) led to the decrease in the inclusion of retinoic acid because the linear structure of sodium dodecyl sulfate made it easier to enter the cavity of CD as compared to less linear retinoic acid. In addition, the in vitro release profile of retinoic acid from CD-GAMNPs was characterized by an initial fast release followed by a delayed release phase

  12. Biocompatible, Biodegradable, and Electroactive Polyurethane-Urea Elastomers with Tunable Hydrophilicity for Skeletal Muscle Tissue Engineering.

    Science.gov (United States)

    Chen, Jing; Dong, Ruonan; Ge, Juan; Guo, Baolin; Ma, Peter X

    2015-12-30

    It remains a challenge to develop electroactive and elastic biomaterials to mimic the elasticity of soft tissue and to regulate the cell behavior during tissue regeneration. We designed and synthesized a series of novel electroactive and biodegradable polyurethane-urea (PUU) copolymers with elastomeric property by combining the properties of polyurethanes and conducting polymers. The electroactive PUU copolymers were synthesized from amine capped aniline trimer (ACAT), dimethylol propionic acid (DMPA), polylactide, and hexamethylene diisocyanate. The electroactivity of the PUU copolymers were studied by UV-vis spectroscopy and cyclic voltammetry. Elasticity and Young's modulus were tailored by the polylactide segment length and ACAT content. Hydrophilicity of the copolymer films was tuned by changing DMPA content and doping of the copolymer. Cytotoxicity of the PUU copolymers was evaluated by mouse C2C12 myoblast cells. The myogenic differentiation of C2C12 myoblasts on copolymer films was also studied by analyzing the morphology of myotubes and relative gene expression during myogenic differentiation. The chemical structure, thermal properties, surface morphology, and processability of the PUU copolymers were characterized by NMR, FT-IR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and solubility testing, respectively. Those biodegradable electroactive elastic PUU copolymers are promising materials for repair of soft tissues such as skeletal muscle, cardiac muscle, and nerve.

  13. Cytocompatibility and Mechanical Properties of Short Phosphate Glass Fibre Reinforced Polylactic Acid (PLA Composites: Effect of Coupling Agent Mediated Interface

    Directory of Open Access Journals (Sweden)

    Gavin Walker

    2012-10-01

    Full Text Available In this study three chemical agents Amino-propyl-triethoxy-silane (APS, sorbitol ended PLA oligomer (SPLA and Hexamethylene diisocyanate (HDI were identified to be used as coupling agents to react with the phosphate glass fibre (PGF reinforcement and the polylactic acid (PLA polymer matrix of the composite. Composites were prepared with short chopped strand fibres (l = 20 mm, ϕ = 20 µm in a random arrangement within PLA matrix. Improved, initial composite flexural strength (~20 MPa was observed for APS treated fibres, which was suggested to be due to enhanced bonding between the fibres and polymer matrix. Both APS and HDI treated fibres were suggested to be covalently linked with the PLA matrix. The hydrophobicity induced by these coupling agents (HDI, APS helped to resist hydrolysis of the interface and thus retained their mechanical properties for an extended period of time as compared to non-treated control. Approximately 70% of initial strength and 65% of initial modulus was retained by HDI treated fibre composites in contrast to the control, where only ~50% of strength and modulus was retained after 28 days of immersion in PBS at 37 °C. All coupling agent treated and control composites demonstrated good cytocompatibility which was comparable to the tissue culture polystyrene (TCP control, supporting the use of these materials as coupling agent’s within medical implant devices.

  14. The effects of crosslinkers on physical, mechanical, and cytotoxic properties of gelatin sponge prepared via in-situ gas foaming method as a tissue engineering scaffold.

    Science.gov (United States)

    Poursamar, S Ali; Lehner, Alexander N; Azami, Mahmoud; Ebrahimi-Barough, Somayeh; Samadikuchaksaraei, Ali; Antunes, A P M

    2016-06-01

    In this study porous gelatin scaffolds were prepared using in-situ gas foaming, and four crosslinking agents were used to determine a biocompatible and effective crosslinker that is suitable for such a method. Crosslinkers used in this study included: hexamethylene diisocyanate (HMDI), poly(ethylene glycol) diglycidyl ether (epoxy), glutaraldehyde (GTA), and genipin. The prepared porous structures were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), thermal and mechanical analysis as well as water absorption analysis. The microstructures of the prepared samples were analyzed using Scanning Electron Microscopy (SEM). The effects of the crosslinking agents were studied on the cytotoxicity of the porous structure indirectly using MTT analysis. The affinity of L929 mouse fibroblast cells for attachment on the scaffold surfaces was investigated by direct cell seeding and DAPI-staining technique. It was shown that while all of the studied crosslinking agents were capable of stabilizing prepared gelatin scaffolds, there are noticeable differences among physical and mechanical properties of samples based on the crosslinker type. Epoxy-crosslinked scaffolds showed a higher capacity for water absorption and more uniform microstructures than the rest of crosslinked samples, whereas genipin and GTA-crosslinked scaffolds demonstrated higher mechanical strength. Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Influence of Functionalization Degree on the Rheological Properties of Isocyanate-Functionalized Chitin- and Chitosan-Based Chemical Oleogels for Lubricant Applications

    Directory of Open Access Journals (Sweden)

    Rocío Gallego

    2014-07-01

    Full Text Available This work deals with the influence of functionalization degree on the thermogravimetric and rheological behaviour of NCO-functionalized chitosan- and chitin-based oleogels. Chitosan and chitin were functionalized using different proportions of 1,6-hexamethylene diisocyanate (HMDI and subsequently dispersed in castor oil to promote the chemical reaction between the –NCO group of the modified biopolymer and the –OH group located in the ricinoleic fatty acid chain of castor oil, thus resulting in different oleogels with specific thermogravimetric and rheological characteristics. Biopolymers and oleogels were characterized through Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (TGA. Small-amplitude oscillatory shear (SAOS measurements were performed on the oleogels. Oleogels presented suitable thermal resistance, despite the fact that the inclusion of HMDI moieties in the polymer structure led to a reduction in the onset temperature of thermal degradation. The insertion of low amounts of HMDI in both chitin and chitosan produces a drastic reduction in the values of oleogel viscoelastic functions but, above a critical threshold, they increase with the functionalization degree so that isocyanate functionalization results in a chemical tool to modulate oleogel rheological response. Several NCO-functionalized chitosan- and chitin-based oleogel formulations present suitable thermal resistance and rheological characteristics to be proposed as bio-based alternatives to traditional lubricating greases.

  16. Manufacturing of biodegradable polyurethane scaffolds based on polycaprolactone using a phase separation method: physical properties and in vitro assay

    Directory of Open Access Journals (Sweden)

    Asefnejad A

    2011-10-01

    Full Text Available Azadeh Asefnejad1, Mohammad Taghi Khorasani2, Aliasghar Behnamghader3, Babak Farsadzadeh1, Shahin Bonakdar4 1Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; 2Iran Polymers and Petrochemical Institute, Tehran, Iran; 3Materials and Energy Research Center, Tehran, Iran; 4National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran Background: Biodegradable polyurethanes have found widespread use in soft tissue engineering due to their suitable mechanical properties and biocompatibility. Methods: In this study, polyurethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and a copolymer of 1,4-butanediol as a chain extender. Polyurethane scaffolds were fabricated by a combination of liquid–liquid phase separation and salt leaching techniques. The effect of the NCO:OH ratio on porosity content and pore morphology was investigated. Results: Scanning electron micrographs demonstrated that the scaffolds had a regular distribution of interconnected pores, with pore diameters of 50–300 µm, and porosities of 64%–83%. It was observed that, by increasing the NCO:OH ratio, the average pore size, compressive strength, and compressive modulus increased. L929 fibroblast and chondrocytes were cultured on the scaffolds, and all samples exhibited suitable cell attachment and growth, with a high level of biocompatibility. Conclusion: These biodegradable polyurethane scaffolds demonstrate potential for soft tissue engineering applications. Keywords: polyurethane, tissue engineering, biodegradable, fibroblast cells

  17. Adhesion of nitrile rubber (NBR) to polyethylene terephthalate (PET) fabric. Part 1: PET surface modification by methylenediphenyl di-isocyanate (MDI)

    Science.gov (United States)

    Razavizadeh, Mahmoud; Jamshidi, Masoud

    2016-01-01

    Fiber to rubber adhesion is an important subject in rubber composite industry. It is well known that surface physical, mechanical and chemical treatments are effective methods to improve interfacial bonding. Ultra violet (UV) light irradiation is an efficient method which is used to increase interfacial interactions. In this research UV assisted chemical modification of PET fabric was used to increase its bonding to nitrile rubber (NBR). NBR is perfect selection to produce fuel and oil resistant rubber parts but it has weak bonding to fabrics. For this purpose at first, the PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was reacted and grafted to carboxylated PET. T-peel test was used to evaluate PET fabric to NBR bonding strength. Attenuated total reflectance-Fourier transform infrared spectroscopy (FTIR-AT) was used to assess surface modifications of the PET fabrics. The chemical composition of the PET surfaces before and after carboxylation and MDI grafting was investigated by X-ray photoelectron spectroscopy (XPS). It was found that at vulcanizing temperature of 150 °C, carboxylation in contrary to MDI grafting, improved considerably PET to NBR adhesion. Finally effect of curing temperature on PET to NBR bonding strength was determined. It was found that increasing vulcanizing temperature to 170 °C caused considerable improvement (about 134%) in bonding strength.

  18. Measurement of emissions during the crosslinking of phenolic resins. Problems with cross-sensibility when determining formaldehyde. Messung von Emissionen bei der Aushaertung von Phenolharzen. Probleme durch Querempfindlichkeiten bei der Bestimmung von Formaldehyd

    Energy Technology Data Exchange (ETDEWEB)

    Haub, H.G.; Muehlhauser, S.; Mueller, F.J.; Gardziella, A. (Bakelite GmbH, Iserlohn (Germany, F.R.))

    1988-04-01

    Phenol and formol (37-50% aqueous solution of formaldehyde) are the main raw materials for the production of phenolic resins. Hexamethylene tetramine is the common constituent for crosslinking when processing phenol novolaks. Most of the today colorimetric methods for the determination of formaldehyde have a strong cross sensibility to hexamethylene tetramine. The error may be 1-2 powers of ten. The only exception is the AHMT-method. Hexamethylene tetramine-containing phenolic resin systems are required for grinding and friction materials, for textile fibre mass and in the foundry industries (croning process). These systems are also used for refractories, for impregnation and for producing carbon and graphite materials. (orig.).

  19. Associations of symptoms related to isocyanate, ureaformol, and formophenolic exposures with respiratory symptoms and lung function in coal miners

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, J.P.; Simon, V.; Chau, N. [Houilleres Bassin Lorraine, Freyming Merlebach (France)

    2007-04-15

    The respiratory effects of diphenylmethane diisocyanate (MDI)-based resins and ureaformol- and formophenolic-based resins, used in coal mining, are unknown. This cross-sectional study of 354 miners evaluated respiratory health in miners with MDI-related symptoms (IS) and ureaformol/formophenolic-related symptoms (UFS). The protocol included clinical examination, chest radiograph, questionnaire on respiratory symptoms, smoking habit, job history, resin handling, and spirometry. Resin handling concerned 27.7% of the miners. IS affected 5.6%, and 1.4% also after work. UFS affected 22.6%, and 2.3% also after work. Wheezing affected 35.6%; chronic cough, expectoration, or bronchitis about 10%; dyspnea 5.4%; and asthma 2.8%. The miners with UFS had significantly more frequent chronic cough, expectoration, chronic bronchitis, dyspnea, and wheezing, whereas those with IS at and after work had markedly lower FVC, FEV1, MMEF, FEF50% and FEF25%. These findings raise the possibility of deleterious effects of exposures to MDI and ureaformol/ ormophenolic resins on respiratory health and lung function in coal miners during their working life.

  20. Preparation and Characterization of Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

    OpenAIRE

    Wenjing Xia; Nianqing Zhu; Rongjie Hou; Wengui Zhong; Mingqing Chen

    2017-01-01

    The polyurethane prepolymer terminated with a double bond was synthesized using isophorone diisocyanate (IPDI), hydroxyl terminated polybutadiene (HTPB), 1,4-butanediol (BDO), and 2-hydroxyethyl acrylate (HEA). Then, a series of innovative UV-curable polyurethane coatings were prepared by blending ene-terminated polyurethane, fluoroacrylate monomer, and multifunctional thiol crosslinker upon UV exposure. The incorporation of fluoroacrylate monomer and multifunctional thiols into polyurethane ...

  1. Castor Oil Based Polyurethanes: Synthesis and Characterization

    Science.gov (United States)

    Macalino, AD; Salen, VA; Reyes, LQ

    2017-09-01

    In this study, polyurethanes based on castor oil and 1,6-hexamethylene diisocyanate (HMDI) were synthesized with varying weight ratio of the castor oil and HMDI. The formation of urethane linkages was verified through the use of a fourier transform infrared spectroscopy (FTIR). The hydrophilicity of the films was evaluated through the use of a contact angle meter and it was found that the contact angle of all the films were below 90 degrees which confirms their hydrophilicity. The thermal stability of the PU films were studies through the use of a thermal gravimetric analyzer and found that all of the polyurethane films exhibited two weight loss events at elevated temperatures wherein the first weight loss event was observed to occur at 285°C to 384°C while the second weight loss event was observed at around 521°C to 551°C. The hardness, elastic modulus, and tensile elongation of the PU films were determined by using a universal testing machine (UTM) where it was found out that the hardness and the elastic modulus of the film is directly proportional with HMDI loading while the tensile elongation is inversely proportional to it. Lastly, it was known through the swelling studies of the PU films that it does not swell, this is due to the presence of unreacted triglycerides in the material, which prevents water from permeating to the films.

  2. Polyethyleneimine-modified superparamagnetic Fe3O4 nanoparticles for lipase immobilization: Characterization and application

    International Nuclear Information System (INIS)

    Khoobi, Mehdi; Motevalizadeh, Seyed Farshad; Asadgol, Zahra; Forootanfar, Hamid; Shafiee, Abbas; Faramarzi, Mohammad Ali

    2015-01-01

    Magnetically separable nanospheres consisting of polyethyleneimine (PEI) and succinated PEI grafted on silica coated magnetite (Fe 3 O 4 ) were prepared and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, vibrating sample magnetometer, scanning electron microscopy and transmission electron microscopy. The prepared magnetic nanoparticles were then applied for physical adsorption or covalent attachment of Thermomyces lanuginosa lipase (TLL) via glutaraldehyde or hexamethylene diisocyanate. The reusability, storage, pH and thermal stabilities of the immobilized enzymes compared to that of free lipase were examined. The obtained results showed that the immobilized lipase on MNPs@PEI-GLU was the best biocatalyst which retained 80% of its initial activity after 12 cycles of application. The immobilized lipase on the selected support (MNPs@PEI-GLU) was also applied for the synthesis of ethyl valerate. Following 24 h incubation of the immobilized lipase on the selected support in n-hexane and solvent free media, the esterification percentages were 72.9% and 28.9%, respectively. - Graphical abstract: A schematic of the preparation of PEI- and succinated PEI-grafted Fe 3 O 4 MNPs (MNPs@PEI) and the immobilization of lipase by covalent bonding and adsorption. - Highlights: • Functionalized polyethylenimine-grafted magnetic nanoparticles were synthesized. • The prepared supports were fully characterized by various analysis methods. • Lipase was immobilized on the nanostructures by adsorption and covalent attachment. • Immobilized lipase produced ethyl valerate in solvent free medium

  3. Polyethyleneimine-modified superparamagnetic Fe{sub 3}O{sub 4} nanoparticles for lipase immobilization: Characterization and application

    Energy Technology Data Exchange (ETDEWEB)

    Khoobi, Mehdi; Motevalizadeh, Seyed Farshad [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 1417614411 (Iran, Islamic Republic of); Asadgol, Zahra [Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran 1417614411 (Iran, Islamic Republic of); Forootanfar, Hamid [Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Kerman University of Medical Sciences, Kerman (Iran, Islamic Republic of); Shafiee, Abbas, E-mail: ashafiee@ams.ac.ir [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran 1417614411 (Iran, Islamic Republic of); Faramarzi, Mohammad Ali, E-mail: faramarz@tums.ac.ir [Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, Tehran 1417614411 (Iran, Islamic Republic of)

    2015-01-15

    Magnetically separable nanospheres consisting of polyethyleneimine (PEI) and succinated PEI grafted on silica coated magnetite (Fe{sub 3}O{sub 4}) were prepared and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, vibrating sample magnetometer, scanning electron microscopy and transmission electron microscopy. The prepared magnetic nanoparticles were then applied for physical adsorption or covalent attachment of Thermomyces lanuginosa lipase (TLL) via glutaraldehyde or hexamethylene diisocyanate. The reusability, storage, pH and thermal stabilities of the immobilized enzymes compared to that of free lipase were examined. The obtained results showed that the immobilized lipase on MNPs@PEI-GLU was the best biocatalyst which retained 80% of its initial activity after 12 cycles of application. The immobilized lipase on the selected support (MNPs@PEI-GLU) was also applied for the synthesis of ethyl valerate. Following 24 h incubation of the immobilized lipase on the selected support in n-hexane and solvent free media, the esterification percentages were 72.9% and 28.9%, respectively. - Graphical abstract: A schematic of the preparation of PEI- and succinated PEI-grafted Fe{sub 3}O{sub 4} MNPs (MNPs@PEI) and the immobilization of lipase by covalent bonding and adsorption. - Highlights: • Functionalized polyethylenimine-grafted magnetic nanoparticles were synthesized. • The prepared supports were fully characterized by various analysis methods. • Lipase was immobilized on the nanostructures by adsorption and covalent attachment. • Immobilized lipase produced ethyl valerate in solvent free medium.

  4. Síntese e caracterização de poliuretanos segmentados contendo blocos de peso molecular controlado: parte 1 preparação e caracterização dos materiais Synthesis and characterization of segmented polyurethanes containing blocks of controlled molecular weight: 1. Materials preparation and characterization

    Directory of Open Access Journals (Sweden)

    C. L. Almeida

    1999-06-01

    molecular weight of 3800, and 1,6-hexamethylene diisocyanate. The molecular weight of these polymers varied acording to the NCO/OH ratio used in the synthesis, always greater than unity, providing -NCO end capped segments. The unreacted HDI was removed under vacuum (10-6-10-8mbar. The molecular weights of the soft segments, SS products, was determined by GPC analytical techniques. The hard segment was prepared from the reaction of the 1,6 hexamethylene diisocyanate and 1,4-butanediol, using a NCO/OH ratio equal to unity. These polymers were functionalized by the addition of an excess BDO after the reaction was completed, providing -OH terminated segments. The unreacted BDO was removed using a solvent. The molecular weights of the hard segments (HS products was determined by MALDI (matrix assisted laser desorption, analytical techniques. The coupling of the soft with the hard segment (SPU products was made in solution (DMF. The characterization of the SPU products was made by infrared, DSC, TGA, and mechanical analytical techniques. The SPU product characteristics were compared to those of a conventional polyurethane (PU, prepared by a prepolymer procedure.

  5. Adhesion of nitrile rubber (NBR) to polyethylene terephthalate (PET) fabric. Part 1: PET surface modification by methylenediphenyl di-isocyanate (MDI)

    International Nuclear Information System (INIS)

    Razavizadeh, Mahmoud; Jamshidi, Masoud

    2016-01-01

    Graphical abstract: - Highlights: • Glutaric anhydride peroxide (GAP) was grafted on PET surface by UV irradiation method. Then MDI was attached to GAP on PET surface. • The fabric was vulcanized by nitrile rubber. • Peet test was performed after each stage of surface modification. • Curing temperature was increased and the tests were repeated. • Effect of MDI coating on PET without carboxylation was evaluated. Effect of vulcanizing temperature on this product was also studied. - Abstract: Fiber to rubber adhesion is an important subject in rubber composite industry. It is well known that surface physical, mechanical and chemical treatments are effective methods to improve interfacial bonding. Ultra violet (UV) light irradiation is an efficient method which is used to increase interfacial interactions. In this research UV assisted chemical modification of PET fabric was used to increase its bonding to nitrile rubber (NBR). NBR is perfect selection to produce fuel and oil resistant rubber parts but it has weak bonding to fabrics. For this purpose at first, the PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was reacted and grafted to carboxylated PET. T-peel test was used to evaluate PET fabric to NBR bonding strength. Attenuated total reflectance-Fourier transform infrared spectroscopy (FTIR-AT) was used to assess surface modifications of the PET fabrics. The chemical composition of the PET surfaces before and after carboxylation and MDI grafting was investigated by X-ray photoelectron spectroscopy (XPS). It was found that at vulcanizing temperature of 150 °C, carboxylation in contrary to MDI grafting, improved considerably PET to NBR adhesion. Finally effect of curing temperature on PET to NBR bonding strength was determined. It was found that increasing vulcanizing temperature to 170 °C caused considerable improvement (about 134%) in bonding strength.

  6. Improving the Distortional Deformation Capabilities of Aerospace Composite Networks

    Science.gov (United States)

    2011-02-28

    and 44DDS/DGEBA will be simulated and compared to experimental analysis. Additionally, matrices of hexamethylene diamine ( HDA ) and bis(hexamethylene...simulation in terms of defining secondary forces, such as hydrogen bonding, and make matrices even more rigid. Our hypothesis was that the HDA /DGEBA and...DGEBA (a) and 33DDS/DGEBA (b). HDA /DGEBA and B-HTA/DGEBA Experimental vs. Simulation Comparison Tensile Modulus, Tg, and density of HDA /DGEBA and B

  7. The effects of crosslinkers on physical, mechanical, and cytotoxic properties of gelatin sponge prepared via in-situ gas foaming method as a tissue engineering scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Poursamar, S. Ali [Institute for Creative Leather Technologies, Park Campus, The University of Northampton, Boughton Green Road, Northampton NN2 7AL (United Kingdom); Lehner, Alexander N. [Centre for Physical Activity and Chronic Disease and the Aging Research Centre, Institute for Health and Wellbeing, School of Health, Park Campus, The University of Northampton, Boughton Green Road, Northampton NN2 7AL (United Kingdom); Azami, Mahmoud; Ebrahimi-Barough, Somayeh [Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Samadikuchaksaraei, Ali [Cellular and Molecular Research Centre, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Department of Tissue Engineering & Regenerative Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Department of Medical Biotechnology, Faculty of Applied Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Antunes, A.P.M., E-mail: Paula.Antunes@northampton.ac.uk [Institute for Creative Leather Technologies, Park Campus, The University of Northampton, Boughton Green Road, Northampton NN2 7AL (United Kingdom)

    2016-06-01

    In this study porous gelatin scaffolds were prepared using in-situ gas foaming, and four crosslinking agents were used to determine a biocompatible and effective crosslinker that is suitable for such a method. Crosslinkers used in this study included: hexamethylene diisocyanate (HMDI), poly(ethylene glycol) diglycidyl ether (epoxy), glutaraldehyde (GTA), and genipin. The prepared porous structures were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), thermal and mechanical analysis as well as water absorption analysis. The microstructures of the prepared samples were analyzed using Scanning Electron Microscopy (SEM). The effects of the crosslinking agents were studied on the cytotoxicity of the porous structure indirectly using MTT analysis. The affinity of L929 mouse fibroblast cells for attachment on the scaffold surfaces was investigated by direct cell seeding and DAPI-staining technique. It was shown that while all of the studied crosslinking agents were capable of stabilizing prepared gelatin scaffolds, there are noticeable differences among physical and mechanical properties of samples based on the crosslinker type. Epoxy-crosslinked scaffolds showed a higher capacity for water absorption and more uniform microstructures than the rest of crosslinked samples, whereas genipin and GTA-crosslinked scaffolds demonstrated higher mechanical strength. Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples. - Highlights: • In-situ gas foaming application in the production of sponge-like gelatin structures • The crosslinkers molecular length impacts on the physical and mechanical properties of the structure. • The effect of crosslinkers on the biocompatibility of gelatin scaffolds.

  8. Airborne thermal degradation products of polyurethene coatings in car repair shops.

    Science.gov (United States)

    Karlsson, D; Spanne, M; Dalene, M; Skarping, G

    2000-10-01

    A methodology for workplace air monitoring of aromatic and aliphatic, mono- and polyisocyanates by derivatisation with di-n-butylamine (DBA) is presented. Air sampling was performed using midget impinger flasks containing 10 ml of 0.01 mol l(-1) DBA in toluene and a glass-fibre filter in series after the impinger flask, thereby providing the possibility of collecting and derivatising isocyanates in both the gas and particle phases. Quantification was made by LC-MS, monitoring the molecular ions [MH]+. Air samples taken with this method in car repair shops showed that many different isocyanates are formed during thermal decomposition of polyurethane (PUR) coatings. In addition to isocyanates such as hexamethylene (HDI), isophorone (IPDI), toluene (TDI) and methylenediphenyl diisocyanate (MDI), monoisocyanates such as methyl (MIC), ethyl (EIC), propyl (PIC), butyl (BIC) and phenyl isocyanate (PhI) were found. In many air samples the aliphatic monoisocyanates dominated. During cutting and welding operations, the highest levels of isocyanates were observed. In a single air sample from a welding operation in a car repair shop, the highest concentrations found were: MIC, 290; EIC, 60; PIC, 20; BIC, 9; PhI, 27; HDI, 105; IPDI, 39; MDI, 4; and 2,4-TDI and 2,6-TDI 140 microg m(-3). Monitoring the particle size distribution and concentration during grinding, welding and cutting operations showed that ultrafine particles (< 0.1 microm) were formed at high concentrations. Isocyanates with low volatility were mainly found in the particle phase, but isocyanates with a relatively high volatility such as TDI, were found in both the particle and gas phases.

  9. The effects of crosslinkers on physical, mechanical, and cytotoxic properties of gelatin sponge prepared via in-situ gas foaming method as a tissue engineering scaffold

    International Nuclear Information System (INIS)

    Poursamar, S. Ali; Lehner, Alexander N.; Azami, Mahmoud; Ebrahimi-Barough, Somayeh; Samadikuchaksaraei, Ali; Antunes, A.P.M.

    2016-01-01

    In this study porous gelatin scaffolds were prepared using in-situ gas foaming, and four crosslinking agents were used to determine a biocompatible and effective crosslinker that is suitable for such a method. Crosslinkers used in this study included: hexamethylene diisocyanate (HMDI), poly(ethylene glycol) diglycidyl ether (epoxy), glutaraldehyde (GTA), and genipin. The prepared porous structures were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), thermal and mechanical analysis as well as water absorption analysis. The microstructures of the prepared samples were analyzed using Scanning Electron Microscopy (SEM). The effects of the crosslinking agents were studied on the cytotoxicity of the porous structure indirectly using MTT analysis. The affinity of L929 mouse fibroblast cells for attachment on the scaffold surfaces was investigated by direct cell seeding and DAPI-staining technique. It was shown that while all of the studied crosslinking agents were capable of stabilizing prepared gelatin scaffolds, there are noticeable differences among physical and mechanical properties of samples based on the crosslinker type. Epoxy-crosslinked scaffolds showed a higher capacity for water absorption and more uniform microstructures than the rest of crosslinked samples, whereas genipin and GTA-crosslinked scaffolds demonstrated higher mechanical strength. Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples. - Highlights: • In-situ gas foaming application in the production of sponge-like gelatin structures • The crosslinkers molecular length impacts on the physical and mechanical properties of the structure. • The effect of crosslinkers on the biocompatibility of gelatin scaffolds

  10. Development of a fast curing tissue adhesive for meniscus tear repair.

    Science.gov (United States)

    Bochyńska, Agnieszka Izabela; Hannink, Gerjon; Janssen, Dennis; Buma, Pieter; Grijpma, Dirk W

    2017-01-01

    Isocyanate-terminated adhesive amphiphilic block copolymers are attractive materials to treat meniscus tears due to their tuneable mechanical properties and good adhesive characteristics. However, a drawback of this class of materials is their relatively long curing time. In this study, we evaluate the use of an amine cross-linker and addition of catalysts as two strategies to accelerate the curing rates of a recently developed biodegradable reactive isocyanate-terminated hyper-branched adhesive block copolymer prepared from polyethylene glycol (PEG), trimethylene carbonate, citric acid and hexamethylene diisocyanate. The curing kinetics of the hyper-branched adhesive alone and in combination with different concentrations of spermidine solutions, and after addition of 2,2-dimorpholinodiethylether (DMDEE) or 1,4-diazabicyclo [2.2.2] octane (DABCO) were determined using FTIR. Additionally, lap-shear adhesion tests using all compositions at various time points were performed. The two most promising compositions of the fast curing adhesives were evaluated in a meniscus bucket handle lesion model and their performance was compared with that of fibrin glue. The results showed that addition of both spermidine and catalysts to the adhesive copolymer can accelerate the curing rate and that firm adhesion can already be achieved after 2 h. The adhesive strength to meniscus tissue of 3.2-3.7 N was considerably higher for the newly developed compositions than for fibrin glue (0.3 N). The proposed combination of an adhesive component and a cross-linking component or catalyst is a promising way to accelerate curing rates of isocyanate-terminated tissue adhesives.

  11. Liquid, urea group-containing polyisocyanate mixtures and plastics derived therefrom

    Energy Technology Data Exchange (ETDEWEB)

    Buethe, I.; Marx, M.; Schoenleben, W.

    1988-04-05

    The invention relates to urea group-containing polyisocyanate mixtures which are liquid at room temperature and have an isocyanate group content of from 15 to 30 weight percent and a diphenylmethane diisocyanate content of from 55 to 90 weight percent. These mixtures are obtained through the reaction of polyoxyalkylene polyamines having a functionality of from 2 to 5 and an amine number from 20 to 250 with a polyisocyanate selected from the group consisting of: a mixture of diphenylmethane diisocyanates and polyphenyl polymethylene polysocyanates having a diphenylmethane diisocyanate content of from 55 to 90 wt%, or at least one diphenylmethane diisocyanate isomer. The polyisocyanate mixtures claimed in the invention are used to prepare dense or cellular polyurethane and/or polyisocyanurate plastics, in particular, flexible polyurethane foams.

  12. Antihistamines suppress upregulation of histidine decarboxylase gene expression with potencies different from their binding affinities for histamine H1 receptor in toluene 2,4-diisocyanate-sensitized rats

    Directory of Open Access Journals (Sweden)

    Hiroyuki Mizuguchi

    2016-04-01

    Full Text Available Antihistamines inhibit histamine signaling by blocking histamine H1 receptor (H1R or suppressing H1R signaling as inverse agonists. The H1R gene is upregulated in patients with pollinosis, and its expression level is correlated with the severity of nasal symptoms. Here, we show that antihistamine suppressed upregulation of histidine decarboxylase (HDC mRNA expression in patients with pollinosis, and its expression level was correlated with that of H1R mRNA. Certain antihistamines, including mepyramine and diphenhydramine, suppress toluene-2,4-diisocyanate (TDI-induced upregulation of HDC gene expression and increase HDC activity in TDI-sensitized rats. However, d-chlorpheniramine did not demonstrate any effect. The potencies of antihistamine suppressive effects on HDC mRNA elevation were different from their H1R receptor binding affinities. In TDI-sensitized rats, the potencies of antihistamine inhibitory effects on sneezing in the early phase were related to H1R binding. In contrast, the potencies of their inhibitory effects on sneezing in the late phase were correlated with those of suppressive effects on HDC mRNA elevation. Data suggest that in addition to the antihistaminic and inverse agonistic activities, certain antihistamines possess additional properties unrelated to receptor binding and alleviate nasal symptoms in the late phase by inhibiting synthesis and release of histamine by suppressing HDC gene transcription.

  13. Pervaporation separation of ethanol-water mixtures using polyethylenimine composite membranes

    Science.gov (United States)

    Neidlinger, H.H.; Schissel, P.O.; Orth, R.A.

    1985-06-19

    Synthetic, organic, polymeric membranes were prepared from polyethylenimine for use with pervaporation apparatus in the separation of ethanol-water mixtures. The polymeric material was prepared in dilute aqueous solution and coated onto a polysulfone support film, from which excess polymeric material was subsequently removed. Cross-links were then generated by limited exposure to toluene-2,4-diisocyanate solution, after which the prepared membrane was heat-cured. The resulting membrane structures showed high selectivity in permeating ethanol or water over a wide range of feed concentrations. 2 tabs.

  14. Facile preparation of pH-responsive polyurethane nanocarrier for oral delivery

    Energy Technology Data Exchange (ETDEWEB)

    Nabid, Mohammad Reza, E-mail: M-nabid@sbu.ac.ir; Omrani, Ismail

    2016-12-01

    This study reports a novel one pot synthesis of pH-responsive nanocarrier for oral delivery of hydrophobic drug under gastrointestinal tract. Triblock copolymer MPEG-HTPB-MPEG was synthesized coupling of MPEG and HTPB using hexamethylene diisocyanate(HDI) and pH-responsive carboxylic acid group was attached to polybuthadiene backbone by thiol-ene click reaction in a facile and convenient procedure. The MPEG-HTPB (g-COOH)-MPEG block copolymers were self-organized into micelle assemblies in the water. The size and shape of the micelle assemblies were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The nanocarriers have high drug loading ability for poorly water-soluble drug. The pH-responsive profile was demonstrated by pH-dependent swelling and in vitro drug release. < 10.0% IBU was released under artificial gastric fluid after 2 h, whereas an immediate release was observed under artificial intestinal fluid. The XTT assay indicated that the micelle obtained from PEG-HTPB (g-COOH)-PEG triblock copolymer are safe in a wide range of concentrations. The results show that pH-responsive PEG-HTPB (g-COOH)-PEG triblock copolymers are promising nanocarriers for the oral administration of hydrophobic drugs. - Highlights: • A facile method for synthesis of pH-responsive nanocarriers was developed. • pH-responsive amphiphilic polymer was synthesized using a rapid and one-pot procedure. • The nanocarriers have high drug loading ability for poorly water-soluble drug. • The nanocarriers show pH-dependent release profile. • The nanocarriers were stable in the gastric fluid and ruptured to release the loaded drug in intestinal fluid.

  15. Facile preparation of pH-responsive polyurethane nanocarrier for oral delivery

    International Nuclear Information System (INIS)

    Nabid, Mohammad Reza; Omrani, Ismail

    2016-01-01

    This study reports a novel one pot synthesis of pH-responsive nanocarrier for oral delivery of hydrophobic drug under gastrointestinal tract. Triblock copolymer MPEG-HTPB-MPEG was synthesized coupling of MPEG and HTPB using hexamethylene diisocyanate(HDI) and pH-responsive carboxylic acid group was attached to polybuthadiene backbone by thiol-ene click reaction in a facile and convenient procedure. The MPEG-HTPB (g-COOH)-MPEG block copolymers were self-organized into micelle assemblies in the water. The size and shape of the micelle assemblies were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The nanocarriers have high drug loading ability for poorly water-soluble drug. The pH-responsive profile was demonstrated by pH-dependent swelling and in vitro drug release. < 10.0% IBU was released under artificial gastric fluid after 2 h, whereas an immediate release was observed under artificial intestinal fluid. The XTT assay indicated that the micelle obtained from PEG-HTPB (g-COOH)-PEG triblock copolymer are safe in a wide range of concentrations. The results show that pH-responsive PEG-HTPB (g-COOH)-PEG triblock copolymers are promising nanocarriers for the oral administration of hydrophobic drugs. - Highlights: • A facile method for synthesis of pH-responsive nanocarriers was developed. • pH-responsive amphiphilic polymer was synthesized using a rapid and one-pot procedure. • The nanocarriers have high drug loading ability for poorly water-soluble drug. • The nanocarriers show pH-dependent release profile. • The nanocarriers were stable in the gastric fluid and ruptured to release the loaded drug in intestinal fluid.

  16. Preparation and characterization of polyvinyl alcohol hydrogels crosslinked by biodegradable polyurethane for tissue engineering of cartilage

    International Nuclear Information System (INIS)

    Bonakdar, Shahin; Emami, Shahriar Hojjati; Shokrgozar, Mohammad Ali; Farhadi, Afshin; Ahmadi, Seyed Amir Hoshiar; Amanzadeh, Amir

    2010-01-01

    Polyurethane was prepared from hexamethylene diisocyanate (HMDI) and polycaprolactone diol (PCL) with stoichiometry ratio of two in a reactor to form prepolymer. Polyvinyl alcohol (PVA) at PVA/prepolymer ratios of 8, 4, 2 and 1 was crosslinked with the former degradable polyester polyurethane. Fourier transform infrared (FTIR) was employed to confirm polyurethane formation during the course of reactions. FTIR spectrum revealed bands at 1729-1733 cm -1 and 3347-3340 cm -1 which indicates carbonyl and NH of amine groups, respectively. Polyurethane formation was also confirmed by the absence of the isocyanate peaks (NCO) at 2270 cm -1 . Dynamic mechanical thermal analysis (DMTA) showed that by increasing prepolymer concentration glass transition temperature decreases from 26 deg. C for PVA to 19 deg. C for sample with PVA/prepolymer ratio of 4 and then it rises up to 31 deg. C. Water uptake measurements illustrated about four fold reduction in swelling ratio of PVA after crosslinking and the sample with equal amounts of PVA and PPU had water uptake of 100%, close to that of a natural cartilage and much less than PVA (425%). All samples had compressive modulus in the range of the articular cartilage (1.9-14.4 MPa). The morphology of the isolated cells on the samples was evaluated by scanning electron microscopy (SEM) and revealed cell attachment and proliferation. The cell viability (3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) and GAG expression (dimethylmethylene blue, DMMB) assays with human chondrocytes on the sample with PVA/prepolymer ratio of one showed about 14 and 33% increase in cell viability and GAG expression after 14 days of culture compare to the PVA, respectively.

  17. Method of coating using active radiation curable polyene-polythiol compositions

    International Nuclear Information System (INIS)

    Morgan, C.R.

    1977-01-01

    A curable composition comprising compatible polyene and polythiol in which both the components ae derived from a hydantoin glycol is claimed. The polyene is typically a reaction product of N,N'-bis(2-hydroxyethyl) dimethylhydantoin, a diisocyanate and an unsaturated alcohol, e.g., allyl alcohol. The polythiol is typically a reaction product of N,N'-bis(2-hydroxyethyl) dimethylhydantoin and a mercapto carboxylic acid, e.g., β-mercaptopropionic acid. Upon exposure to a free radical generator, e.g., actinic radiation, this polyene-polythiol composition cures to solid, insoluble, chemically resistant, cross-linked polythioether products

  18. Opportunities and obstacles in translating evidence to policy in occupational asthma.

    Science.gov (United States)

    Tarlo, Susan M; Arif, Ahmed A; Delclos, George L; Henneberger, Paul; Patel, Jenil

    2018-06-01

    Occupational asthma (OA), a common respiratory disorder in Western countries, is caused by exposures at the workplace. It is part of a broader definition of work-related asthma (WRA) that also includes pre-existing asthma aggravated by substances present in the workplace environment, and it is potentially preventable. The purpose of this paper is to illustrate preventive measures for occupational asthma by case studies. In three case studies we discuss preventive measures that have been associated with reductions in incidence of occupational asthma from natural rubber latex and from diisocyanates as supported by published literature. We also discuss challenges in relation to asthma from cleaning products in healthcare work. Several preventive measures have been associated with reduction in incidence of occupational asthma from natural rubber latex and from diisocyanates, and may provide lessons for prevention of other causes of occupational asthma. Cleaning products remain an unresolved problem at present with respect to asthma risks but potential measures include the use of safer products and safer applications such as avoidance of spray products, use of occupational hygiene methods such as improving local ventilation, and when appropriate, the use of personal protective devices. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Improved Procedure for Preparation of Covalently Bonded Cellulose Tris-phenylcarbamate Chiral Stationary Phases

    Institute of Scientific and Technical Information of China (English)

    秦峰; 陈小明; 刘月启; 邹汉法; 王俊德

    2005-01-01

    The classical method for preparation of covalently boned cellulose derivative chiral stationary phases (CSP) with diisocyanate as spacer was improved. Diisocyanate was firstly allowed to react with 3-aminopropyltriethoxysilane, and the resulting product was then applied as the spacer reagent to immobilize cellulose derivatives onto silica gel. Influences of the amount and the length of the spacer on the optical resolution ability of the CSP were investigated. Comparing improved procedure to classical diisocyanate method, the cross-linking between the glucose units of the cellulose derivatives was avoided to the most extent. With the improved procedure, regio-nonselective ways could be adooted to prepare covalently bonded CSP, which showed an advantage for the rapid preparation.

  20. Polyurethanes Crosslinked with Poly(vinyl alcohol as a Slowly-Degradable and Hydrophilic Materials of Potential Use in Regenerative Medicine

    Directory of Open Access Journals (Sweden)

    Justyna Kucińska-Lipka

    2018-02-01

    Full Text Available Novel, slowly-degradable and hydrophilic materials with proper mechanical properties and surface characteristics are in great demand within the biomedical field. In this paper, the design, synthesis, and characterization of polyurethanes (PUR crosslinked with poly(vinyl alcohol (PVA as a new proposition for regenerative medicine is described. PVA-crosslinked PURs were synthesized by a two-step polymerization performed in a solvent (dimethylsulfoxide, DMSO. The raw materials used for the synthesis of PVA-crosslinked PURs were poly(ε-caprolactone (PCL, 1,6-hexamethylene diisocyanate (HDI, and PVA as a crosslinking agent. The obtained materials were studied towards their physicochemical, mechanical, and biological performance. The tests revealed contact angle of the materials surface between 38–47° and tensile strength in the range of 41–52 MPa. Mechanical characteristics of the obtained PURs was close to the characteristics of native human bone such as the cortical bone (TSb = 51–151 MPa or the cancellous bone (TSb = 10–20 MPa. The obtained PVA-crosslinked PURs did not show significant progress of degradation after 3 months of incubation in a phosphate-buffered saline (PBS. Accordingly, the obtained materials may behave similar to slowly-degradable materials, which can provide long-term physical support in, for example, tissue regeneration, as well as providing a uniform calcium deposition on the material surface, which may influence, for example, bone restoration. A performed short-term hemocompatibility study showed that obtained PVA-crosslinked PURs do not significantly influence blood components, and a cytotoxicity test performed with the use of MG 63 cell line revealed the great cytocompatibility of the obtained materials. According to the performed studies, such PVA-crosslinked PURs may be a suitable proposition for the field of tissue engineering in regenerative medicine.

  1. Enhancement of antibacterial properties of polyurethanes by chitosan and heparin immobilization

    International Nuclear Information System (INIS)

    Kara, Filiz; Aksoy, E. Ayse; Yuksekdag, Zehranur; Aksoy, Serpil; Hasirci, Nesrin

    2015-01-01

    Graphical abstract: - Highlights: • Polyurethane elastomer was synthesized in medical purity. • Chitosan (CH) and heparin (Hep) were immobilized on polyurethane films. • Modification with CH and Hep increased hydrophilicity and surface free energy. • Immobilized films had high antibacterial activity against four bacteria. • Bacterial adhesion significantly decreased on the modified surfaces. - Abstract: Being antibacterial is a required property for the materials used in medical devices and instruments. Polyurethanes (PUs) are one class of polymers widely used in the production of devices that especially come in contact with blood (e.g. heart valves, blood vessels, vascular grafts and catheters). In this study, hexamethylene diisocyanate based polyurethanes (PUh) were synthesized and antibacterial and anti-adhesive properties were added by immobilizing chitosan (CH) and heparin (Hep) on the samples of PUh via a stepwise process. Chemistry and topography of the modified film samples (PUh-CH and PUh-CH-Hep) were examined by Fourier Transform Infrared Spectrophotometry-Attenuated Total Reflectance (FTIR-ATR), Electron Spectroscopy for Chemical Analysis (ESCA) and Atomic Force Microscopy (AFM), and surface free energy (SFE) values after each step were determined by goniometer. PUh-CH and PUh-CH-Hep samples were found to be antibacterial against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) (both Gram positive) and Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) (both Gram negative) bacteria, and bacterial adhesion results showed a significant decrease in the number of viable bacteria on both modified samples where PUh-CH-Hep was the most effective. The findings of this study show that polymeric surfaces can be effectively modified and converted to be antibacterial by chitosan and heparin immobilization, and presence of both chemicals enhance efficacy against bacteria.

  2. In vitro and biomechanical screening of polyethylene glycol and poly(trimethylene carbonate) block copolymers for annulus fibrosus repair.

    Science.gov (United States)

    Long, Rose G; Rotman, Stijn G; Hom, Warren W; Assael, Dylan J; Illien-Jünger, Svenja; Grijpma, Dirk W; Iatridis, James C

    2018-02-01

    Herniated intervertebral discs (IVDs) are a common cause of back and neck pain. There is an unmet clinical need to seal annulus fibrosus (AF) defects, as discectomy surgeries address acute pain but are complicated by reherniation and recurrent pain. Copolymers of polyethylene glycol with trimethylene carbonate (TMC) and hexamethylene diisocyanate (HDI) end-groups were formulated as AF sealants as the HDI form covalent bonds with native AF tissue. TMC adhesives were evaluated and optimized using the design criteria: stable size, strong adherence to AF tissue, high cytocompatibility, restoration of IVD biomechanics to intact levels following in situ repair, and low extrusion risk. TMC adhesives had high adhesion strength as assessed with a pushout test (150 kPa), and low degradation rates over 3 weeks in vitro. Both TMC adhesives had shear moduli (220 and 490 kPa) similar to, but somewhat higher than, AF tissue. The adhesive with three TMC moieties per branch (TMC3) was selected for additional in situ testing because it best matched AF shear properties. TMC3 restored torsional stiffness, torsional hysteresis area and axial range of motion to intact states. However, in a failure test of compressive deformation under fixed 5 ° flexion, some herniation risk was observed with failure strength of 5.9 MPa compared with 13.5 MPa for intact samples; TMC3 herniated under cyclic organ culture testing. These TMC adhesives performed well during in vitro and in situ testing, but additional optimization to enhance failure strength is required to further this material to advanced screening tests, such as long-term degradation. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  3. A new approach to fabrication of Cs/BG/CNT nanocomposite scaffold towards bone tissue engineering and evaluation of its properties

    Energy Technology Data Exchange (ETDEWEB)

    Shokri, S. [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Movahedi, B., E-mail: b.movahedi@ast.ui.ac.ir [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Rafieinia, M. [Biosensor Research Center, Department of Advanced Medical Technology, Isfahan University of Medical Sciences, Isfahan, 64716 (Iran, Islamic Republic of); Salehi, H. [Department of Anatomical Sciences, Isfahan University of Medical Sciences, Isfahan, 64716 (Iran, Islamic Republic of)

    2015-12-01

    Graphical abstract: - Highlights: • Nanocomposite scaffold was produced using a novel technique. • Bioactive glass, carbon nanotube and chitosan were used for fabrication of nanocomposite scaffold. • The compressive strength of the scaffold was near to the cancellous bone. • Biodegradability of the scaffolds in PBS shows the slow destruction. - Abstract: In the present study, bioactive glass (BG), carbon nanotube (CNT), and chitosan (Cs) were used with different ratios for the fabrication of nanocomposite scaffold for bone tissue engineering. BG was synthesized by sol–gel process and CNT was functionalized by immersing in sulfuric acid as well as nitric acid. Nanocomposite scaffold was produced using a novel technique, hot press, and salt leaching process and cross-linked by Hexamethylene diisocyanate (HDI). The optimum porosity of the scaffold with respect to the ratio of salt and precursor was kept around 70%. Mechanical properties of the scaffolds were increased by the addition of CNT and hence, the compressive strength of them with 4 wt% CNT was increased up to 5.95 ± 0.5 MPa. The nanocomposite scaffolds were characterized by FT-IR, SEM, XRD, and electrochemical analysis. Furthermore, scaffolds were immersed in PBS for evaluating the biodegradability, water absorption, and CNT release. The results indicated that water absorption of the scaffolds was increased by adding CNT to the scaffold. The amount of released CNT after 30 days was measured within 6 × 10{sup −4} and 1 × 10{sup −3} mg/ml. Attachment and proliferation of MG63 osteoblast cell line on Cs/BG/CNT scaffolds were investigated by MTT assay indicating no toxicity for this nanocomposite scaffolds. According to the results of the experiments, the nanocomposite scaffold with modified composition (Cs/BG/CNT, 80:20:2 wt%) was the best one in matters of mechanical, chemical, and cellular properties and also the most appropriate for trabecular bone tissue.

  4. Enhancement of antibacterial properties of polyurethanes by chitosan and heparin immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Kara, Filiz [Department of Chemistry, Faculty of Science, Gazi University, 06500 Ankara (Turkey); Aksoy, E. Ayse [Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Hacettepe University, 06100 Ankara (Turkey); Yuksekdag, Zehranur [Biotechnology Laboratory, Department of Biology, Faculty of Science, Gazi University, 06500 Ankara (Turkey); Aksoy, Serpil [Department of Chemistry, Faculty of Science, Gazi University, 06500 Ankara (Turkey); Hasirci, Nesrin, E-mail: nhasirci@metu.edu.tr [BIOMATEN, Center of Excellence in Biomaterials and Tissue Engineering, Middle East Technical University, 06800 Ankara (Turkey); Department of Chemistry, Faculty of Arts and Sciences, Middle East Technical University, 06800 Ankara (Turkey)

    2015-12-01

    Graphical abstract: - Highlights: • Polyurethane elastomer was synthesized in medical purity. • Chitosan (CH) and heparin (Hep) were immobilized on polyurethane films. • Modification with CH and Hep increased hydrophilicity and surface free energy. • Immobilized films had high antibacterial activity against four bacteria. • Bacterial adhesion significantly decreased on the modified surfaces. - Abstract: Being antibacterial is a required property for the materials used in medical devices and instruments. Polyurethanes (PUs) are one class of polymers widely used in the production of devices that especially come in contact with blood (e.g. heart valves, blood vessels, vascular grafts and catheters). In this study, hexamethylene diisocyanate based polyurethanes (PUh) were synthesized and antibacterial and anti-adhesive properties were added by immobilizing chitosan (CH) and heparin (Hep) on the samples of PUh via a stepwise process. Chemistry and topography of the modified film samples (PUh-CH and PUh-CH-Hep) were examined by Fourier Transform Infrared Spectrophotometry-Attenuated Total Reflectance (FTIR-ATR), Electron Spectroscopy for Chemical Analysis (ESCA) and Atomic Force Microscopy (AFM), and surface free energy (SFE) values after each step were determined by goniometer. PUh-CH and PUh-CH-Hep samples were found to be antibacterial against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) (both Gram positive) and Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) (both Gram negative) bacteria, and bacterial adhesion results showed a significant decrease in the number of viable bacteria on both modified samples where PUh-CH-Hep was the most effective. The findings of this study show that polymeric surfaces can be effectively modified and converted to be antibacterial by chitosan and heparin immobilization, and presence of both chemicals enhance efficacy against bacteria.

  5. Preparation and characterization of polyvinyl alcohol hydrogels crosslinked by biodegradable polyurethane for tissue engineering of cartilage

    Energy Technology Data Exchange (ETDEWEB)

    Bonakdar, Shahin [Biomedical Engineering Department, Amirkabir University of Technology, Tehran, 15875-4413 (Iran, Islamic Republic of); Emami, Shahriar Hojjati, E-mail: shahriar16@yahoo.com [Biomedical Engineering Department, Amirkabir University of Technology, Tehran, 15875-4413 (Iran, Islamic Republic of); Shokrgozar, Mohammad Ali [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, 13164 (Iran, Islamic Republic of); Farhadi, Afshin [Tehran Azad University of Medical Science, Amiralmomenin Hospital (Iran, Islamic Republic of); Ahmadi, Seyed Amir Hoshiar [Biomedical Engineering Department, Amirkabir University of Technology, Tehran, 15875-4413 (Iran, Islamic Republic of); Amanzadeh, Amir [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, 13164 (Iran, Islamic Republic of)

    2010-05-10

    Polyurethane was prepared from hexamethylene diisocyanate (HMDI) and polycaprolactone diol (PCL) with stoichiometry ratio of two in a reactor to form prepolymer. Polyvinyl alcohol (PVA) at PVA/prepolymer ratios of 8, 4, 2 and 1 was crosslinked with the former degradable polyester polyurethane. Fourier transform infrared (FTIR) was employed to confirm polyurethane formation during the course of reactions. FTIR spectrum revealed bands at 1729-1733 cm{sup -1} and 3347-3340 cm{sup -1} which indicates carbonyl and NH of amine groups, respectively. Polyurethane formation was also confirmed by the absence of the isocyanate peaks (NCO) at 2270 cm{sup -1}. Dynamic mechanical thermal analysis (DMTA) showed that by increasing prepolymer concentration glass transition temperature decreases from 26 deg. C for PVA to 19 deg. C for sample with PVA/prepolymer ratio of 4 and then it rises up to 31 deg. C. Water uptake measurements illustrated about four fold reduction in swelling ratio of PVA after crosslinking and the sample with equal amounts of PVA and PPU had water uptake of 100%, close to that of a natural cartilage and much less than PVA (425%). All samples had compressive modulus in the range of the articular cartilage (1.9-14.4 MPa). The morphology of the isolated cells on the samples was evaluated by scanning electron microscopy (SEM) and revealed cell attachment and proliferation. The cell viability (3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) and GAG expression (dimethylmethylene blue, DMMB) assays with human chondrocytes on the sample with PVA/prepolymer ratio of one showed about 14 and 33% increase in cell viability and GAG expression after 14 days of culture compare to the PVA, respectively.

  6. Preparation and Characterization of Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

    Directory of Open Access Journals (Sweden)

    Wenjing Xia

    2017-08-01

    Full Text Available The polyurethane prepolymer terminated with a double bond was synthesized using isophorone diisocyanate (IPDI, hydroxyl terminated polybutadiene (HTPB, 1,4-butanediol (BDO, and 2-hydroxyethyl acrylate (HEA. Then, a series of innovative UV-curable polyurethane coatings were prepared by blending ene-terminated polyurethane, fluoroacrylate monomer, and multifunctional thiol crosslinker upon UV exposure. The incorporation of fluoroacrylate monomer and multifunctional thiols into polyurethane coatings significantly enhanced the hydrophobic property, mechanical property, pencil hardness, and glossiness of the polyurethane coatings. This method of preparing UV crosslinkable, hydrophobic polyurethane coatings based on thiol-ene chemistry exhibited numerous advantages over other UV photocuring systems.

  7. Intermedia transfer factors for fifteen toxic pollutants released to air basins in California

    Energy Technology Data Exchange (ETDEWEB)

    McKone, T.E.; Daniels, J.I. [Lawrence Livermore National Lab., CA (United States); Chiao, F.F.; Hsieh, D.P.H. [Univ. of California, Davis, CA (United States)

    1993-10-01

    This report provides a summary definition of the intermedia-transfer factors (ITFs). Methods are discussed for estimating these parameters in the absence of measured values, and the estimation errors inherent in these estimation methods are considered. A detailed summary is provided of measured and estimated ITF values for fifteen air contaminants. They include: 1,3 butadiene; cadmium; cellosolve; cellosolve acetate; chloroform; di-2-ethylhexylphthalate; 1,4-dioxame; hexachlorobenzene; inorganic arsenic; inorganic lead; nickel; tetrachloroethylene; toluene; toluene-2,4-diisocyanate; and 1,3-xylene. Recommendations are made regarding the expected value and variance in these values for use in exposure models.

  8. Characterization of Functionalized Polyurethane Foam for Lead Ion Removal from Water

    Directory of Open Access Journals (Sweden)

    Subhashini Gunashekar

    2014-01-01

    Full Text Available Polyurethane foams functionalized with sulfonic acid groups are used in this study to exchange lead (Pb2+ ions from aqueous solutions. Toluene-2, 4-diisocyanate, 2,6-diisocyanate (TDI was reacted with Polypropylene glycol 1200 (PPG in 2 : 1 molar ratio to form a linear prepolymer. The linear prepolymer was further polymerized using N,N-bis(2-hydroxyethyl-2-aminoethanesulfonic acid (BES, which acts both as a chain extender and an ion-exchanger for Pb2+ ions. The functionalized polyurethane foam was characterized by Fourier transform infrared spectroscopy (FTIR, gel permeation chromatography (GPC, scanning electron microscopy (SEM, and energy dispersive X-ray spectroscopy (EDX. The Pb2+ ion exchange capacity was determined using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS. The maximum Pb2+ ion exchange capacity of the foam was found to be 51 ppb/g from a 100 ppb Pb2+ solution over a period of two hours. In addition, pH analysis was carried out on the foam composition with the best Pb2+ ion removal capacity. The pH results based on two-hour exposures showed that the functionalized polyurethane foam performed better at lower pH levels.

  9. Dispersiones acuosas de poliuretano bloqueado: una alternativa como agente curtiente Aqueous dispersions of blocked polyurethane: an alternative as tanning agents

    Directory of Open Access Journals (Sweden)

    José Luis Mata-Mata

    2008-06-01

    Full Text Available Se sintetizaron y se evaluaron como agentes curtientes de pieles vacunas dos tipos de agentes de reticulación base poliuretano bloqueado. Se presentan los resultados de la síntesis de dispersiones acuosas de poliuretano bloqueado (DPU’s, basadas en prepolímeros a partir de la reacción de los diisocianatos alifáticos H12MDI (4,4’ metilenbis-ciclohexilisocianato y HDI (hexametilendiisocianato con polioles base poliéter óxido de etileno de peso molecular 1 y 2 KDa, en una relación molar isocianato/oxhidrilo (NCO/OH de 4:1 y 6:1 a 100 °C por 2 y 4 horas. En una segunda reacción, los grupos isocianato (NCO libres del prepolímero se bloquearon con una solución acuosa de NaHSO3 ó Na2S2O5 al 40%p/p. Los prepolímeros se caracterizaron mediante espectroscopia IR y RMN de ¹H. El tanto por ciento de isocianato libre en el prepolímero, así como el bloqueo de dichos grupos, se determinaron por espectroscopía IR. La evaluación de la capacidad curtiente de las DPU’s se determinó de acuerdo a la estabilidad térmica de la piel (temperatura de desnaturalización, mediante Calorimetría Diferencial de Barrido (DSC y a la determinación del índice de reticulación de las DPU’s con la colágena de la piel mediante un ensayo con ninhidrina.Two types of crosslinking agents blocked polyurethanes were synthesized and evaluated as tanning agents of bovine skins. The results of the synthesis of aqueous dispersions of blocked polyurethane (DPU’s are presented. They were based on prepolymers from the reaction of the aliphatic diisocyanates H12MDI 4,4’-methylenebis(cyclohexyl isocyanate and HDI (hexamethylene diisocyanate with HO-polyols such as polyethylene oxide of molecular weight 1 and 2 kDa. The molar NCO/OH ratio was fixed in 4:1 or 6:1, at 100 °C and 2 or 4 hours for the reaction time. In a second reaction, the prepolymer containing terminal NCO groups were blocked by reaction with an aqueous NaHSO3 or Na2S2O5 solution to 40% w/w. The

  10. Fabrication and thermal stability studies of polyamide 66 containing ...

    Indian Academy of Sciences (India)

    Administrator

    by two-step polymerization reaction with adipic acid hexamethylene salt (AH salt) and bis(4-carboxyphenyl) .... polymerization autoclave (Weihai-controlled reactor Ltd,. WHF-2) equipped ... After melt polymerization, the molten copolymer was.

  11. Sorption of oil in the polyurethane from oil or castor oil; Sorcao de oleo no poliuretano derivado do petroleo ou do oleo de mamona

    Energy Technology Data Exchange (ETDEWEB)

    Florentino, Wagner M; Goulart, Shane A.S.; Mulinari, Daniella R. [Centro Universitario de Volta Redonda (UniFOA), Volta Redonda, RJ (Brazil)], e-mail: wagner-can@hotmail.com

    2011-07-01

    The oil outpouring has caused serious environmental problems. To minimize this damage polyurethane foams have been used. In this work, the use of polyurethane from oil and castor oil, in different polyol/diisocyanate mass ratios, to absorb oil was evaluated. Results revealed that the proportion of polyol and diisocyanate influenced in the sorption capacity and the polyurethane from castor oil presented greater sorption capacity. Of this way, can say that the polyurethane from oil can be replaced by castor oil, contributing to sustainable development. (author)

  12. Investigation of the stable combustion of initiating explosives at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Fogelzang, A.E.; Egorshev, V.IU.; Pimenov, A.IU.; Sinditskii, V.P.; Saklantii, A.R.

    1985-01-01

    The combustion of typical initiating explosives - tetrazene, tricycloacetone peroxide, diazodinitrophenol, hexamethylene triperoxide diamine, and cyanur triazide - was studied experimentally in the 0.1-40 MPa pressure range. The dependence of combustion rate on pressure was studied for these explosives. 8 references.

  13. Stereocomplexation, Thermal and Mechanical Properties of Conetworks Composed of Star-Shaped l-Lactide, d-Lactide and ε-Caprolactone Oligomers Utilizing Sugar Alcohols as Core Molecules

    Directory of Open Access Journals (Sweden)

    Kaito Sugane

    2017-11-01

    Full Text Available It is important to develop tailor-made biodegradable/biocompatible polymer networks usable for biomaterials whose thermal and mechanical properties are easily controlled by changing the composition. We synthesized sugar-alcohol-based polymer networks (SPN-mscLAO/3CLO, m = 4, 5 or 6 by the crosslinking reactions of erythritol, xylitol or sorbitol-based m-armed star-shaped l-lactide and d-lactide oligomers (HmSLLAO and HmSDLAO, a glycerol-based 3-armed star-shaped ε-caprolactone oligomer (H3SCLO and hexamethylene diisocyanate (HDI at the weight ratios of HmSLLAO/HmSDLAO = 1/1 and (HmSLLAO + HmSDLAO/H3CLO = 100/0, 75/25, 50/50, 25/75 or 0/100. The influence of the arm number on the crystallization behavior, thermal and mechanical properties of SPN-mscLAO/3CLOs were systematically investigated by comparing with those of sugar-alcohol-based homochiral polymer network (SPN-mLLAO, m = 4, 5 or 6 prepared by the reaction of HmSLLAO and HDI. Stereocomplex (sc crystallites are dominantly formed for SPN-mscLAO/3CLOs 100/0–25/75, whereas SPN-mLLAOs were amorphous. The higher order of melting temperature of sc-crystals for SPN-mscLAO/3CLOs 100/0–25/75 was m = 5 > m = 6 > m = 4. The sc-crystallinities of SPN-4scLAO/3CLOs 100/0–50/50 were significantly lower than those of SPN-mscLAO/3CLOs 100/0–50/50 (m = 5 and 6. The larger order of the sc-spherulite size at crystallization temperature of 110 °C was m = 5 > m = 6 > m = 4 for SPN-mscLAO/3CLO 100/0. The size and number of sc-spherulites decreased with increasing crystallization temperature over the range of 110–140 °C and with increasing CLO fraction. Among all the networks, SPN-5scLAO/3CLOs 75/25 and 50/50 exhibited the highest and second highest tensile toughnesses (21.4 and 20.3 MJ·m−3, respectively.

  14. Development of biodegradable hyper-branched tissue adhesives for the repair of meniscus tears.

    Science.gov (United States)

    Bochyńska, A I; Van Tienen, T G; Hannink, G; Buma, P; Grijpma, D W

    2016-03-01

    Meniscus tears are one of the most commonly occurring injuries of the knee joint. Current meniscus repair techniques are challenging and do not bring fully satisfactory results. Tissue adhesives are a promising alternative, since they are easy to apply and cause minimal tissue trauma. In this study, a series of amphiphilic copolymers based on polyethylene glycol, trimethylene carbonate and citric acid were synthesized and subsequently end-functionalized with hexamethylene diisocyanate to form reactive adhesive materials. The shear adhesive strength of the networks to bovine meniscus tissue measured in a lap-shear adhesion test ranged between 20 and 80 kPa, which was better than for fibrin glue (10 kPa). The elastic modulus of the networks depended on composition and was in the same range as that of human meniscus. Cell compatibility was assessed using Alamar Blue staining after incubation of the bovine meniscus cells with different concentrations of the glues for 7 days. Cell viability was not affected after adding up to 3mg of the adhesive/mL of medium. The proposed materials are suitable candidates to be used as resorbable tissue adhesives for meniscus repair. They have excellent mechanical and adhesive properties that can be adjusted by varying the composition of the copolymers. Meniscal tears often occur and current treatment strategies do not bring fully satisfactory results. Use of biodegradable tissue adhesives would be an interesting option, but currently available adhesives are not suited due to toxicity or poor mechanical properties. Here, we describe the development of novel biodegradable, hyper-branched, adhesive copolymers. These adhesives cure upon contact with water forming flexible networks. Their adhesion to bovine meniscus tissue was significantly better than that of clinically used fibrin glue. The tensile properties of the cured networks were in the same range of values of the human meniscus. When physiologically relevant amounts were added to

  15. Polyurethane Binder Systems for Polymer Bonded Explosives

    Science.gov (United States)

    2006-12-01

    Propulsion (2005), Santiago , Chile . 8. Huang, C.-C., Hwu, W.-H., Cheng, C.-S., Shyy, I.-N., and Yang, K.-K., Study on Thermal Decomposition of Composite...water or amines to form ureas (Figure 2). R NCO R N C O H+ H2O O H R NH2 - CO2 R NCO R N C O NR’ H H ureaamine Figure 2. Reaction of an isocyanate...Monoisocyanates are present as impurities in low concentration in most diisocyanates. Table 1. Common diisocyanates Isocyanate Structure B.p. (ºC

  16. Precise Measurement of Refractive Index and Absorption Coefficient of Near Millimeter Wave and Far Infrared Materials.

    Science.gov (United States)

    1987-06-01

    polyethylene. The plexiglass is a polymethyl methacrylate and the acrylic is a polymethacrylate . The polyamide(nylon) is made with adipic acid and hexamethylene...are made with acrylic acid . It was not sur- prizing to see both exhibiting similar absorption characteristics atleast 30 times higher than

  17. USSR Report, Life Sciences, Biomedical and Behavioral Sciences

    Science.gov (United States)

    1987-02-18

    received one tablet of the multivitamin "Hexavit" as a supplement to their diet. The ration was vacuum-packed, wrapped in three layers of polymer...salicylate, hexamethylene tetramine, etc.) and increasing the useful life of many parenteral drugs (pyrodoxine HC1, norsulfazole, isoniazid

  18. Medium wave exposure characterisation using exposure quotients.

    Science.gov (United States)

    Paniagua, Jesús M; Rufo, Montaña; Jiménez, Antonio; Antolín, Alicia; Pinar, Iván

    2010-06-01

    One of the aspects considered in the International Commission on Non-Ionizing Radiation Protection guidelines is that, in situations of simultaneous exposure to fields of different frequencies, exposure quotients for thermal and electrical stimulation effects should be examined. The aim of the present work was to analyse the electromagnetic radiation levels and exposure quotients for exposure to multiple-frequency sources in the vicinity of medium wave radio broadcasting antennas. The measurements were made with a spectrum analyser and a monopole antenna. Kriging interpolation was used to prepare contour maps and to estimate the levels in the towns and villages of the zone. The results showed that the exposure quotient criterion based on electrical stimulation effects to be more stringent than those based on thermal effects or power density levels. Improvement of dosimetry evaluations requires the spectral components of the radiation to be quantified, followed by application of the criteria for exposure to multiple-frequency sources.

  19. Radiation curing applications of palm oil acrylates

    International Nuclear Information System (INIS)

    Mohd Hilmi Mahmood; Khairul Zaman; Rida, Anak Tajau; Mek Zah Salleh; Rosley Che Ismail

    2007-01-01

    Various palm oil based urethan acrylate prepolymers (UP) were prepared from palm oil based polyols, diisocyanate compounds and hydroxyl terminated acrylate monomers by following procedure derived from established methods. The products were compared with each other in term of their molecular weights (MW), viscosities, curing speed by UV irradiation, gel contents and film hardness. The molecular structure of diisocyanate compounds and hydroxyl acrylate monomers were tend to determine the molecular weights and hence viscosities of the final products of urethan acrylate prepolymers (UP), whereas, the MW of the UP has no direct effects on the UV curing properties of the prepolymers. (author)

  20. Exposure Forecaster

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Exposure Forecaster Database (ExpoCastDB) is EPA's database for aggregating chemical exposure information and can be used to help with chemical exposure...

  1. Exposure levels and determinants of inhalable dust exposure in bakeries.

    Science.gov (United States)

    Burstyn, I; Teschke, K; Kennedy, S M

    1997-12-01

    The study's objectives were to measure full-shift exposure to inhalable dust in bakeries and define the determinants of full-shift exposure. Inhalable dust was measured gravimetrically. Ninety-six bakery workers, employed in seven different bakeries, participated in the study. Two side-by-side full-shift inhalable dust samples were obtained from each study participant on a single occasion. Samples were collected on 18 days selected at random. During the entire sampling period, bakers were observed and information on 14 different tasks was recorded at 15 min intervals. Other production characteristics were also recorded for each sampling day. These task and production variables were used in statistical modelling to identify significant predictors of exposure. The mean full-shift inhalable dust exposure was 8.2 mg/m3 (range: 0.1-110 mg/m3). A regression model explained 79% of the variability in exposure. The model indicated that tasks such as weighing, pouring and operating dough-brakers and reversible sheeters increased the exposure, while packing, catching and decorating decreased the exposure. Bread and bun production lines were associated with increased full-shift inhalable dust exposure, while cake production and substitution of dusting with the use of divider oil were associated with decreased exposure. Production tasks and characteristics are strong predictors of personal full-shift exposures to flour dust among bakers; these can be altered to reduce exposure levels.

  2. Exploring Global Exposure Factors Resources for Use in Consumer Exposure Assessments

    Science.gov (United States)

    Zaleski, Rosemary T.; Egeghy, Peter P.; Hakkinen, Pertti J.

    2016-01-01

    This publication serves as a global comprehensive resource for readers seeking exposure factor data and information relevant to consumer exposure assessment. It describes the types of information that may be found in various official surveys and online and published resources. The relevant exposure factors cover a broad range, including general exposure factor data found in published compendia and databases and resources about specific exposure factors, such as human activity patterns and housing information. Also included are resources on exposure factors related to specific types of consumer products and the associated patterns of use, such as for a type of personal care product or a type of children’s toy. Further, a section on using exposure factors for designing representative exposure scenarios is included, along with a look into the future for databases and other exposure science developments relevant for consumer exposure assessment. PMID:27455300

  3. Fast exposure time decision in multi-exposure HDR imaging

    Science.gov (United States)

    Piao, Yongjie; Jin, Guang

    2012-10-01

    Currently available imaging and display system exists the problem of insufficient dynamic range, and the system cannot restore all the information for an high dynamic range (HDR) scene. The number of low dynamic range(LDR) image samples and fastness of exposure time decision impacts the real-time performance of the system dramatically. In order to realize a real-time HDR video acquisition system, this paper proposed a fast and robust method for exposure time selection in under and over exposure area which is based on system response function. The method utilized the monotony of the imaging system. According to this characteristic the exposure time is adjusted to an initial value to make the median value of the image equals to the middle value of the system output range; then adjust the exposure time to make the pixel value on two sides of histogram be the middle value of the system output range. Thus three low dynamic range images are acquired. Experiments show that the proposed method for adjusting the initial exposure time can converge in two iterations which is more fast and stable than average gray control method. As to the exposure time adjusting in under and over exposed area, the proposed method can use the dynamic range of the system more efficiently than fixed exposure time method.

  4. Optical Properties of Hexamethylene-Tetraselenafulvalinium Tetracyanoquinodi-Methanide (HMTSF-TCNQ)

    DEFF Research Database (Denmark)

    Jacobsen, C. S.; Bechgaard, Klaus; Andersen, Jan Rud

    1977-01-01

    conducting direction displays a plasma edge. An analysis yields a plasmon frequency ohgrp = 7400 cm–1, an inverse life time lambda = 1300 cm–1, and an optical mass m* = 1.9 mo. The low-temperature reflectance gives ohgrp = 8200 cm–1 and a 2.4 times longer lifetime, consistent with the temperature dependence...

  5. Residual Isocyanates in Medical Devices and Products: A Qualitative and Quantitative Assessment

    Directory of Open Access Journals (Sweden)

    Gillian Franklin

    2016-01-01

    Full Text Available We conducted a pilot qualitative and quantitative assessment of residual isocyanates and their potential initial exposures in neonates, as little is known about their contact effect. After a neonatal intensive care unit (NICU stockroom inventory, polyurethane (PU and PU foam (PUF devices and products were qualitatively evaluated for residual isocyanates using Surface SWYPE ™ . Those containing isocyanates were quantitatively tested for methylene diphenyl diisocyanate (MDI species, using UPLC-UV-MS/MS method. Ten of 37 products and devices tested, indicated both free and bound residual surface isocyanates; PU/PUF pieces contained aromatic isocyanates; one product contained aliphatic isocyanates. Overall, quantified mean MDI concentrations were low (4,4‘-MDI = 0.52 to 140.1 pg/mg and (2,4‘-MDI = 0.01 to 4.48 pg/mg. The 4,4‘-MDI species had the highest measured concentration (280 pg/mg. Commonly used medical devices/products contain low, but measurable concentrations of residual isocyanates. Quantifying other isocyanate species and neonatal skin exposure to isocyanates from these devices and products requires further investigation.

  6. Occupational radiation exposure in Germany: many monitored persons = high exposure?

    International Nuclear Information System (INIS)

    Nitschke, J.

    1996-01-01

    Natural radiation affects the entire population in Germany, and most of Germany's inhabitants are exposed to medical radiation in their lifetime. Occupational radiation exposure, however, is a kind of exposure affecting only a limited and well-defined group of the population, and this radiation exposure has been recorded and monitored as precisely as technically possible ever since the radiation protection laws made occupational radiation exposure monitoring a mandatory obligation. Official personal dosimetry applying passive dosemeters in fact does not offer direct protection against the effects of ionizing radiation, as dosemeter read-out and dose calculation is a post-exposure process. But it nevertheless is a rewarding monitoring duty under radiation protection law, as is shown by the radiation exposure statistics accumulated over decades: in spite of the number of monitored persons having been increasing over the years, the total exposure did not, due to the corresponding improvements in occupational radiation protection. (orig.) [de

  7. Radon daughter exposure estimation and its relation to the exposure limit

    International Nuclear Information System (INIS)

    Stocker, H.

    1981-10-01

    Under current Atomic Energy Control Regulations, the annual limit for individual exposure to radon daughters is 4 WLM. The Regulations do not specify how the exposure is to be determined nor to what accuracy the measurements should be made. This paper discusses the historical and conventional grab-sampling and time-weighting methods for assigning exposures to radon daughters in uranium mines in Canada. As a further step in the evolution of exposure assignments, the system of personal radon daughter dosimetry is introduced as the more accurate means of assigning individual exposures and of adhering to the intent of the exposure limit

  8. The Australian Work Exposures Study: Prevalence of Occupational Exposure to Formaldehyde.

    Science.gov (United States)

    Driscoll, Timothy R; Carey, Renee N; Peters, Susan; Glass, Deborah C; Benke, Geza; Reid, Alison; Fritschi, Lin

    2016-01-01

    The aims of this study were to produce a population-based estimate of the prevalence of work-related exposure to formaldehyde, to identify the main circumstances of exposure and to describe the use of workplace control measures designed to decrease those exposures. The analysis used data from the Australian Workplace Exposures Study, a nationwide telephone survey, which investigated the current prevalence and exposure circumstances of work-related exposure to 38 known or suspected carcinogens, including formaldehyde, among Australian workers aged 18-65 years. Using the web-based tool OccIDEAS, semi-quantitative information was collected about exposures in the current job held by the respondent. Questions were addressed primarily at tasks undertaken rather than about self-reported exposures. Of the 4993 included respondents, 124 (2.5%) were identified as probably being exposed to formaldehyde in the course of their work [extrapolated to 2.6% of the Australian working population-265 000 (95% confidence interval 221 000-316 000) workers]. Most (87.1%) were male. About half worked in technical and trades occupations. In terms of industry, about half worked in the construction industry. The main circumstances of exposure were working with particle board or plywood typically through carpentry work, building maintenance, or sanding prior to painting; with the more common of other exposures circumstances being firefighters involved in fighting fires, fire overhaul, and clean-up or back-burning; and health workers using formaldehyde when sterilizing equipment or in a pathology laboratory setting. The use of control measures was inconsistent. Workers are exposed to formaldehyde in many different occupational circumstances. Information on the exposure circumstances can be used to support decisions on appropriate priorities for intervention and control of occupational exposure to formaldehyde, and estimates of burden of cancer arising from occupational exposure to formaldehyde

  9. The report of medical exposures in diagnostic radiology. Pt. 1. The questionnaire of medical exposure and standard radiation exposure

    International Nuclear Information System (INIS)

    Sasakawa, Yasuhiro; Matsumura, Yoshitaka; Iwasaki, Takanobu; Segawa, Hiroo; Yasuda, Sadatoshi; Kusuhara, Toshiaki

    1997-01-01

    We had made reports of patient radiation exposure for doctors to judge adaptation of medical radiation rightly. By these reports the doctors can be offered data of exposure dose and somatic effect. First, we sent out questionnaires so that we grasped the doctor's understanding about radiation exposure. Consequently we understood that the doctors had demanded data of exposure dose and somatic effect. Secondly, by the result of questionnaires we made the tables of exposure dose about radiological examination. As a result we have be able to presume exposure dose about high radiation sensitive organization as concrete figures. (author)

  10. Designing exposure registries for improved tracking of occupational exposure and disease.

    Science.gov (United States)

    Arrandale, Victoria H; Bornstein, Stephen; King, Andrew; Takaro, Timothy K; Demers, Paul A

    2016-06-27

    Registries are one strategy for collecting information on occupational exposure and disease in populations. Recently leaders in the Canadian occupational health and safety community have shown an interest in the use of occupational exposure registries. The primary goal of this study was to review a series of Canadian exposure registries to identify their strengths and weaknesses as a tool for tracking occupational exposure and disease in Canada. A secondary goal was to identify the features of an exposure registry needed to specifically contribute to prevention, including the identification of new exposure-disease relationships. A documentary review of five exposure registries from Canada was completed. Strengths and limitations of the registries were compared and key considerations for designing new registries were identified. The goals and structure of the exposure registries varied considerably. Most of the reviewed registries had voluntary registration, which presents challenges for the use of the data for either surveillance or epidemiology. It is recommended that eight key issues be addressed when planning new registries: clear registry goal(s), a definition of exposure, data to be collected (and how it will be used), whether enrolment will be mandatory, as well as ethical, privacy and logistical considerations. When well constructed, an exposure registry can be a valuable tool for surveillance, epidemiology and ultimately the prevention of occupational disease. However, exposure registries also have a number of actual and potential limitations that need to be considered.

  11. The effect of oxidation on the enzyme-catalyzed hydrolytic biodegradation of poly(urethane)s.

    Science.gov (United States)

    Labow, Rosalind S; Tang, Yiwen; McCloskey, Christopher B; Santerre, J Paul

    2002-01-01

    Although the biodegradation of polyurethanes (PU) by oxidative and hydrolytic agents has been studied extensively, few investigations have reported on the combination of their effects. Since neutrophils (PMN) arrive at an implanted device first and release HOCl, followed by monocyte-derived macrophages (MDM) which have potent esterase activities and oxidants of their own, the combined effect of oxidative and hydrolytic degradation on radiolabeled polycarbonate-polyurethanes (PCNU)s was investigated and compared to that of a polyester-PU (PESU) and a polyether-PU (PEU). The PCNUs were synthesized with PCN (MW = 1,000), and butanediol (14C-BD) and one of two diisocyanates, hexane-1,6-diisocyanate (14C-HDI) or methylene bis-p-phenyl diisocyanate (MDI). The PESU and PEU were synthesized using toluene-diisocyanate (14C-TDI), with polycaprolactone and polytetramethylene oxide as soft segments respectively, and ethylene diamine as the chain extender. The effect of pre-treatment with 0.1 mM HOC1 for 1 week on the HDI-based PCNUs and both TDI-based PUs resulted in a significant inhibition of radiolabel release (RR) elicited by cholesterol esterase (CE), when compared to buffer alone, whereas the MDI-based PCNU showed a small but significant increase. When PMN were activated on the HDI-based PCNU surface with phorbol myristate acetate (PMA), HOCl was released for 3 h, and was almost completely abolished by sodium azide (AZ). Simultaneously, the PMN-elicited RR, shown previously to be due to the esterolytic cleavage by serine proteases, was inhibited approximately 75% by PMA-activation of the cells, but significantly increased relative to the latter when AZ was added. Both in vitro oxidation by HOCl and the release of HOCI by PMN were associated with the inhibition of RR and suggest perturbations between oxidative and hydrolytic mechanisms of biodegradation.

  12. Intracellular Delivery of siRNA by Polycationic Superparamagnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Betzaida Castillo

    2012-01-01

    Full Text Available The siRNA transfection efficiency of nanoparticles (NPs, composed of a superparamagnetic iron oxide core modified with polycationic polymers (poly(hexamethylene biguanide or branched polyethyleneimine, were studied in CHO-K1 and HeLa cell lines. Both NPs demonstrated to be good siRNA transfection vehicles, but unmodified branched polyethyleneimine (25 kD was superior on both cell lines. However, application of an external magnetic field during transfection (magnetofection increased the efficiency of the superparamagnetic NPs. Furthermore, our results reveal that these NPs are less toxic towards CHO-K1 cell lines than the unmodified polycationic-branched polyethyleneimine (PEI. In general, the external magnetic field did not alter the cell’s viability nor it disrupted the cell membranes, except for the poly(hexamethylene biguanide-modified NP, where it was observed that in CHO-K1 cells application of the external magnetic field promoted membrane damage. This paper presents new polycationic superparamagnetic NPs as promising transfection vehicles for siRNA and demonstrates the advantages of magnetofection.

  13. Integrated toxic evaluation of sulfamethazine on zebrafish: Including two lifespan stages (embryo-larval and adult) and three exposure periods (exposure, post-exposure and re-exposure).

    Science.gov (United States)

    Yan, Zhengyu; Yang, Qiulian; Jiang, Weili; Lu, Jilai; Xiang, Zhongrun; Guo, Ruixin; Chen, Jianqiu

    2018-03-01

    Persistence of antibiotics in aquatic environment may pose a risk to the non-target aquatic organisms. This study provided an integrated evaluation to analyze the toxic stress of sulfamethazine (SMZ) on zebrafish in two lifespan stages (embryo-larval and adult) and three exposure periods (exposure, post-exposure and re-exposure). Zebrafish embryos and adult zebrafish were exposed to SMZ at 0.2, 20 and 2000 μg/L, respectively. The results showed that SMZ at any given concentration inhibited the hatching of embryos at 58-96 hpf (hours post-fertilization). Our result also indicated that two major kinds of the malformation, which was induced by the antibiotic, were edema and spinal curvature. Additionally, the antibiotic stimulated the heartbeat while reduced the body length of the embryo at 72 hpf. Superoxide dismutase (SOD) activities and malondialdehyde (MDA) contents significantly increased at 120 hpf when the embryos were exposed to the lowest concentration (0.2 μg/L) of the antibiotic. On the other hand, the antibiotic induced SOD activities and MDA contents in adult zebrafish in the exposure and re-exposure periods. The MDA contents could recover while SOD activities still increased in 2 d after the exposure. Both SOD activities and MDA contents could recover in 7 d after the exposure. Levels of SOD and MDA in the re-exposure were higher than those in the first exposure. Our results suggested that SMZ had toxic effects on both embryos and adult zebrafish, and provided an integrated evaluation of the toxic effects of SMZ on zebrafish at a new perspective. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effect of structure and molecular weight on properties of pressure sensitive adhesives (PSA) formulated from palm oil based urethane acrylate (POBUA)

    International Nuclear Information System (INIS)

    Mohd Hilmi Mahmood; Shahrol Najmin Baharom; Rida Tajau; Mek Zah Salleh; Khairul Zaman Mohd Dahlan; Rosley Che Ismail

    2004-01-01

    Various palm oil (RBD Palm Olein) based urethane acrylate prepolymers (UPs) having different structures and molecular weight were synthesized from palm oil based polyols, diisocyanate compounds and hydroxyl terminated acrylate monomers by following established synthesis procedures described elsewhere. The products (UPs) were compared with each other in term of their molecular weight (MW), viscosities and UV curing performances of pressure sensitive adhesives (PSA) UP based formulations. The molecular structure of diisocyanate compounds and hydroxyl acrylate monomers tend to determine the molecular weight and hence viscosities of the final products of urethane acrylate prepolymers (UP), whereas, the MW of the UP has no direct effects on the coatings and adhesive properties of UV curable UP based PSA. (Author)

  15. Radiation exposure records management

    International Nuclear Information System (INIS)

    Boiter, H.P.

    1975-12-01

    Management of individual radiation exposure records begins at employment with the accumulation of data pertinent to the individual and any previous occupational radiation exposure. Appropriate radiation monitorinng badges or devices are issued and accountability established. A computer master file is initiated to include the individual's name, payroll number, social security number, birth date, assigned department, and location. From this base, a radiation exposure history is accumulated to include external ionizing radiation exposure to skin and whole body, contributing neutron exposure, contributing tritium exposure, and extremity exposure. It is used also to schedule bioassay sampling and in-vivo counts and to provide other pertinent information. The file is used as a basis for providing periodic reports to management and monthly exposure summaries to departmental line supervision to assist in planning work so that individual annual exposures are kept as low as practical. Radiation exposure records management also includes documentation of radiation surveys performed by the health physicist to establish working rates and the individual estimating and recording his estimated exposure on a day-to-day basis. Exposure information is also available to contribute to Energy Research and Development Administration statistics and to the National Transuranium Registry

  16. Ytterbium triflate as a new catalyst on the curing of epoxy-isocyanate based thermosets

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Marjorie; Fernandez-Francos, Xavier [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili, Marcelli Domingo s/n, 43007 Tarragona (Spain); Morancho, Josep M. [Laboratori de Termodinamica, ETSEIB, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Serra, Angels [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili, Marcelli Domingo s/n, 43007 Tarragona (Spain); Ramis, Xavier, E-mail: ramis@mmt.upc.es [Laboratori de Termodinamica, ETSEIB, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain)

    2012-09-10

    Highlights: Black-Right-Pointing-Pointer Ytterbium triflate is an active catalyst for diepoxides/diisocyanate formulations. Black-Right-Pointing-Pointer Ytterbium triflate promotes the formation of oxazolidone, isocyanurate, urethane and allophanate groups and the polyetherification of epoxides. Black-Right-Pointing-Pointer Diepoxides/diisocyanate formulations catalyzed by ytterbium triflate show higher pot-life than equivalent formulations catalyzed by benzyldimethylamine. - Abstract: Networks containing oxazolidone, isocyanurate, urethane, allophanate and ether groups were prepared by copolymerization of mixtures of diglycidylether of bisphenol A and toluene-2,4-diisocyanate in presence of ytterbium triflate. It has been demonstrated that ytterbium triflate promotes six elemental reactions that coexist during curing and yield the aforementioned groups. Changes during curing, fraction of different groups present in the network and final properties of the cured materials were investigated by thermal analysis and infrared spectroscopy. The influence of the molar ratio of isocyanate to epoxide groups on the properties and curing has been studied. The curing kinetics were analyzed by means of an integral isoconversional non-isothermal procedure. The results obtained were compared with those obtained by using a common catalyst such as the benzyldimethylamine. The structure and the properties of the resulting thermosets are controlled by the initial composition of the formulation and the catalyst used.

  17. Polymerization of impregnated monomer in wood by microwave irradiation

    International Nuclear Information System (INIS)

    Kawase, Kaoru; Hayakawa, Kiyoshi

    1976-01-01

    The manufacturing of a wood-plastic combination (WPC) by irradiation of microwave (2,450 and 915 +- 50 MHz) or gamma-ray was carried out. After the impregnation of dry woods (Hinoki: Chamaecyparis obtusa Endl., Buna: Acer mono Maxim., and Kaede: Fagus crenata Blume) with the mixture of the vinyl monomers and chemical reagents, the monomer in wood was polymerized by irradiation. In case of polymerization with microwave (2,450 MHz) the effect of oxygen was not recognized, but in the case of gamma-ray the rate of polymerization remarkably decreased in the presence of oxygen. The polymerization of various monomers was carried out also in the air, and the conversions of styrene, methyl-, ethyl-, n-propyl-, and n-butyl-methacrylate were 51.8 -- 89.1%, but that of vinyl acetate was lower (4.3 -- 8.2%). The conversion of monomers with irradiation of 915 MHz microwave was very low (2.6 -- 33.5%). The conversion of monomers increased when toluylene diisocyanate was added in the monomers. The percentage of extraction with hot benzene of WPC (chip) decreased by the addition of toluylene diisocyanate. It was concluded from C.H.N. analyses that the reaction took place among the wood, toluylene diisocyanate and methyl methacrylate. (auth.)

  18. Biological monitoring of occupational exposure to N,N-dimethylformamide--the effects of co-exposure to toluene or dermal exposure.

    Science.gov (United States)

    Yang, J S; Kim, E A; Lee, M Y; Park, I J; Kang, S K

    2000-09-01

    The objective of this study is to assess the exposure and intake dose of N,N-dimethylformamide (DMF) and the correlation between them, according to the type of exposure for the workers in the DMF industry. We monitored 345 workers occupationally exposed to DMF, from 15 workshops in the synthetic fiber, fiber coating, synthetic leather and paint manufacturing industries. Ambient monitoring was carried out with personal samplers to monitor the external exposure. Biological monitoring was done to determine the internal dose by analyzing N-methylformamide (NMF) in end-shift urine. Work procedure and exposure type of each DMF workshop was carefully surveyed, to classify workers by exposure type according to work details. Workers were classified into three groups (Group A: continuous and direct exposure through inhalation and skin; Group B: intermittent and short-term exposure through inhalation and skin; Group C: continuous and indirect exposure mostly through inhalation). Geometric mean of DMF concentration in air was 2.62 (GSD 5.30) ppm and that of NMF in urine was 14.50 (GSD 3.89) mg/l. In the case of continuous absorption through inhalation and dermal exposure (Group A), the value of NMF in urine corresponding to 10 ppm of DMF was 45.3 mg/l (r = 0.524, n = 178), 39.1 mg/g creatinine (r = 0.424), while it was 37.7 mg/l (r = 0.788, n = 37), 24.2 mg/g creatinine (r = 0.743) in the case of absorption mostly through inhalation (Group C). Creatinine correction reduced the correlation between two parameters. The NMF in urine corresponding to 10 ppm DMF, of the dermal and inhalation exposure group was 39.1 mg/g creatinine (r = 0.424, n = 178), while that of the inhalation exposure-only group was 24.2 mg/g creatinine (r = 0.743, n = 37). Co-exposure with toluene reduced the NMF excretion in urine.

  19. EPA EcoBox Tools by Exposure Pathways - Exposure Pathways In ERA

    Science.gov (United States)

    Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

  20. Biodegradable block poly(ester-urethane)s based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymers.

    Science.gov (United States)

    Ou, Wenfeng; Qiu, Handi; Chen, Zhifei; Xu, Kaitian

    2011-04-01

    A series of block poly(ester-urethane)s (abbreviated as PU3/4HB) based on biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) segments were synthesized by a facile way of melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent and stannous octanoate (Sn(Oct)(2)) as catalyst, with different 4HB contents and segment lengths. The chemical structure, molecular weight and distribution were systematically characterized by (1)H nuclear magnetic resonance spectrum (NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hydrophilicity was investigated by static contact angle of deionized water and CH(2)I(2). DSC curves revealed that the PU3/4HB polyurethanes have their T(g) from -25.6 °C to -4.3 °C, and crystallinity from 2.5% to 25.3%, being almost amorphous to semi-crystalline. The obtained PU3/4HBs are hydrophobic (water contact angle 77.4°-95.9°), and their surface free energy (SFE) were studied. The morphology of platelets adhered on the polyurethane film observed by scanning electron microscope (SEM) showed that platelets were activated on the PU3/4HB films which would lead to blood coagulation. The lactate dehydrogenase (LDH) assay revealed that the PU3/4HBs displayed higher platelet adhesion property than raw materials and biodegradable polymer polylactic acid (PLA) and would be potential hemostatic materials. Crystallinity degree, hydrophobicity, surface free energy and urethane linkage content play important roles in affecting the LDH activity and hence the platelet adhesion. CCK-8 assay showed that the PU3/4HB is non-toxic and well for cell growth and proliferation of mouse fibroblast L929. It showed that the hydrophobicity is an important factor for cell growth while 3HB content of the PU3/4HB is important for the cell proliferation. Through changing the

  1. A Technique: Exposure Therapy

    Directory of Open Access Journals (Sweden)

    Serkan AKKOYUNLU

    2013-07-01

    Full Text Available Introduction: Exposure with response prevention is an effective treatment for all anxiety disorders. According to the behavioral learning theories, fears which are conditioned via classical conditioning are reinforced by respondent conditioning. Avoidance and safety seeking behaviors prevent disconfirmation of anxious beliefs. In exposure client faces stimulates or cues that elicit fear or distress, by this avoidance is inhibited. Clients are also encouraged to resists performing safety seeking behaviors or rituals that they utilize to reduce fear or distress. Accomplishing these habituation or extinction is achieved. In addition to this clients learn that feared consequences does not realize or not harmful as they believed by experiencing. Emotional processing is believed to be the mechanism of change in exposure.Objective: The aim of this review is to provide a definition of exposure and its effectiveness briefly, and describe how to implement exposure, its steps and remarkable aspects using. Exposure therapies and treatments that involve exposure are proved to be effective in all anxiety disorders. Exposure therapy can be divided in three parts: Assessment and providing a treatment rationale, creating an exposure hierarchy and response prevention plan, implementing exposure sessions. Clients must also continue to perform exposure between sessions. Therapy transcripts are also provided to exemplify these parts. Conclusion: Exposure with response prevention is a basic and effective technique. Every cognitive behavior therapist must be able to implement this technique and be cognizant of pearls of this procedure.

  2. Occupational exposures and chronic obstructive pulmonary disease (COPD): comparison of a COPD-specific job exposure matrix and expert-evaluated occupational exposures.

    Science.gov (United States)

    Kurth, Laura; Doney, Brent; Weinmann, Sheila

    2017-03-01

    To compare the occupational exposure levels assigned by our National Institute for Occupational Safety and Health chronic obstructive pulmonary disease-specific job exposure matrix (NIOSH COPD JEM) and by expert evaluation of detailed occupational information for various jobs held by members of an integrated health plan in the Northwest USA. We analysed data from a prior study examining COPD and occupational exposures. Jobs were assigned exposure levels using 2 methods: (1) the COPD JEM and (2) expert evaluation. Agreement (Cohen's κ coefficients), sensitivity and specificity were calculated to compare exposure levels assigned by the 2 methods for 8 exposure categories. κ indicated slight to moderate agreement (0.19-0.51) between the 2 methods and was highest for organic dust and overall exposure. Sensitivity of the matrix ranged from 33.9% to 68.5% and was highest for sensitisers, diesel exhaust and overall exposure. Specificity ranged from 74.7% to 97.1% and was highest for fumes, organic dust and mineral dust. This COPD JEM was compared with exposures assigned by experts and offers a generalisable approach to assigning occupational exposure. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  3. A novel kind of concrete superplasticizer based on aryl isocyanate polycondensates

    Science.gov (United States)

    Ding, Bei; Qian, Shanshan; Qiu, Ying; Wang, Yi; Zheng, Chunyang; Wang, Gaoming

    2017-03-01

    A novel superplasticizer was synthesized by polycondensation of Alkyl phenol phosphate and toluene diisocyanate grafting with methoxy polyoxyethylene ether (MPEG). The chemical structure and molecular weight of polycondensates molecules were determined by 1H nuclear magnetic resonance (NMR) and gel permeation chromatography respectively. The experimental results indicated that the polycondensates of Alkyl phenol phosphate and toluene diisocyanate grafting with MPEG not only exhibited good water-reducing properties but also demonstrated effective anti-clay abilities alone. Furthermore, the polycondensates showed good fluidity maintaining abilities within 1-3 h and good workability of concrete. The results of T500 Time experiments show that lower plastic viscosity of the polycondensates leads to fresh concrete much “looser” than conventional PCEs in self-compacting concrete.

  4. Nanoparticle exposure biomonitoring: exposure/effect indicator development approaches

    Science.gov (United States)

    Marie-Desvergne, C.; Dubosson, M.; Lacombe, M.; Brun, V.; Mossuz, V.

    2015-05-01

    The use of engineered nanoparticles (NP) is more and more widespread in various industrial sectors. The inhalation route of exposure is a matter of concern (adverse effects of air pollution by ultrafine particles and asbestos). No NP biomonitoring recommendations or standards are available so far. The LBM laboratory is currently studying several approaches to develop bioindicators for occupational health applications. As regards exposure indicators, new tools are being implemented to assess potentially inhaled NP in non-invasive respiratory sampling (nasal sampling and exhaled breath condensates (EBC)). Diverse NP analytical characterization methods are used (ICP-MS, dynamic light scattering and electron microscopy coupled to energy-dispersive X-ray analysis). As regards effect indicators, a methodology has been developed to assess a range of 29 cytokines in EBCs (potential respiratory inflammation due to NP exposure). Secondly, collaboration between the LBM laboratory and the EDyp team has allowed the EBC proteome to be characterized by means of an LC-MS/MS process. These projects are expected to facilitate the development of individual NP exposure biomonitoring tools and the analysis of early potential impacts on health. Innovative techniques such as field-flow fractionation combined with ICP-MS and single particle-ICPMS are currently being explored. These tools are directly intended to assist occupational physicians in the identification of exposure situations.

  5. Nanoparticle exposure biomonitoring: exposure/effect indicator development approaches

    International Nuclear Information System (INIS)

    Marie-Desvergne, C; Dubosson, M; Mossuz, V; Lacombe, M; Brun, V

    2015-01-01

    The use of engineered nanoparticles (NP) is more and more widespread in various industrial sectors. The inhalation route of exposure is a matter of concern (adverse effects of air pollution by ultrafine particles and asbestos). No NP biomonitoring recommendations or standards are available so far. The LBM laboratory is currently studying several approaches to develop bioindicators for occupational health applications. As regards exposure indicators, new tools are being implemented to assess potentially inhaled NP in non-invasive respiratory sampling (nasal sampling and exhaled breath condensates (EBC)). Diverse NP analytical characterization methods are used (ICP-MS, dynamic light scattering and electron microscopy coupled to energy-dispersive X-ray analysis). As regards effect indicators, a methodology has been developed to assess a range of 29 cytokines in EBCs (potential respiratory inflammation due to NP exposure). Secondly, collaboration between the LBM laboratory and the EDyp team has allowed the EBC proteome to be characterized by means of an LC-MS/MS process. These projects are expected to facilitate the development of individual NP exposure biomonitoring tools and the analysis of early potential impacts on health. Innovative techniques such as field-flow fractionation combined with ICP-MS and single particle-ICPMS are currently being explored. These tools are directly intended to assist occupational physicians in the identification of exposure situations. (paper)

  6. Eliminating the mere exposure effect through changes in context between exposure and test.

    Science.gov (United States)

    de Zilva, Daniel; Mitchell, Chris J; Newell, Ben R

    2013-01-01

    The present study examined the extent to which increased liking of exposed stimuli--the mere exposure effect--is dependent on experiencing the stimuli in the same context in exposure and on test. Participants were repeatedly exposed to pairs of cues (nonsense words) and target stimuli (faces and shapes), and were asked to rate the pleasantness of the target stimuli in a subsequent test phase. Familiar targets were preferred to novel targets-a mere exposure effect was obtained. This preference for familiar targets was disrupted, however, when the cue-target pairings were rearranged between exposure and test, or a novel cue was introduced at test. Overall, the study suggests that the context of exposure and test moderates the mere exposure effect. Liking of stimuli due to exposure is specific to the context of exposure and does not apply to new or familiar but different contexts.

  7. Presidential Green Chemistry Challenge: 2005 Greener Reaction Conditions Award

    Science.gov (United States)

    Presidential Green Chemistry Challenge 2005 award winner, BASF, invented a one-component, urethane acrylate oligomer primer system for automobile refinishing that is UV-curable, has VOCs, and is free of diisocyanates.

  8. Personal exposure control system

    International Nuclear Information System (INIS)

    Tanabe, Ken-ichi; Akashi, Michio

    1994-01-01

    Nuclear power stations are under strict radiation control. Exposure control for nuclear workers is the most important operation, and so carefully thought out measures are taken. This paper introduces Fuji Electric's personal exposure control system that meets strict exposure control and rationalizes control operations. The system has a merit that it can provide required information in an optimum form using the interconnection of a super minicomputer and exposure control facilities and realizes sophisticated exposure control operations. (author)

  9. Application of maximum radiation exposure values and monitoring of radiation exposure

    International Nuclear Information System (INIS)

    1996-01-01

    The guide presents the principles to be applied in calculating the equivalent dose and the effective dose, instructions on application of the maximum values for radiation exposure, and instruction on monitoring of radiation exposure. In addition, the measurable quantities to be used in monitoring the radiation exposure are presented. (2 refs.)

  10. Affecting Factors of Secondhand Smoke Exposure in Korea: Focused on Different Exposure Locations.

    Science.gov (United States)

    Sun, Li Yuan; Cheong, Hae Kwan; Lee, Eun Whan; Kang, Kyeong Jin; Park, Jae Hyun

    2016-09-01

    Exposure to secondhand smoke (SHS) not only can cause serious illness, but is also an economic and social burden. Contextual and individual factors of non-smoker exposure to SHS depend on location. However, studies focusing on this subject are lacking. In this study, we described and compared the factors related to SHS exposure according to location in Korea. Regarding individual factors related to SHS exposure, a common individual variable model and location-specific variable model was used to evaluate SHS exposure at home/work/public locations based on sex. In common individual variables, such as age, and smoking status showed different relationships with SHS exposure in different locations. Among home-related variables, housing type and family with a single father and unmarried children showed the strongest positive relationships with SHS exposure in both males and females. In the workplace, service and sales workers, blue-collar workers, and manual laborers showed the strongest positive association with SHS exposure in males and females. For multilevel analysis in public places, only SHS exposure in females was positively related with cancer screening rate. Exposure to SHS in public places showed a positive relationship with drinking rate and single-parent family in males and females. The problem of SHS embodies social policies and interactions between individuals and social contextual factors. Policy makers should consider the contextual factors of specific locations and regional and individual context, along with differences between males and females, to develop effective strategies for reducing SHS exposure.

  11. OCCUPATIONAL EXPOSURE AND COPD

    DEFF Research Database (Denmark)

    Würtz, Else Toft

    Chronic Obstructive Pulmonary Disease (COPD) is a common disease. The main risk factor is smoking although 15% of the COPD cases are expected to be preventable if the occupational exposures from vapour, gas, dust, and fume were eliminated; the population attributable fraction (PAF). The thesis...... addresses the association between occupational exposure and COPD in a population-based cohort of Danes aged 45-84-years. 4717 participants were included at baseline and 2624 at the four year follow-up. COPD was defined by spirometry and the occupational exposure was based on specialist defined jobs...... and questionnaires. The main occupational exposure was organic dust and 49% reported no lifetime occupational exposure. The results suggest occupational exposures to be associated to COPD also in never smokers and women. We found an exposure-response relation in the cross sectional analyses. The results...

  12. Contaminant exposure in terrestrial vertebrates

    International Nuclear Information System (INIS)

    Smith, Philip N.; Cobb, George P.; Godard-Codding, Celine; Hoff, Dale; McMurry, Scott T.; Rainwater, Thomas R.; Reynolds, Kevin D.

    2007-01-01

    Here we review mechanisms and factors influencing contaminant exposure among terrestrial vertebrate wildlife. There exists a complex mixture of biotic and abiotic factors that dictate potential for contaminant exposure among terrestrial and semi-terrestrial vertebrates. Chemical fate and transport in the environment determine contaminant bioaccessibility. Species-specific natural history characteristics and behavioral traits then play significant roles in the likelihood that exposure pathways, from source to receptor, are complete. Detailed knowledge of natural history traits of receptors considered in conjunction with the knowledge of contaminant behavior and distribution on a site are critical when assessing and quantifying exposure. We review limitations in our understanding of elements of exposure and the unique aspects of exposure associated with terrestrial and semi-terrestrial taxa. We provide insight on taxa-specific traits that contribute, or limit exposure to, transport phenomenon that influence exposure throughout terrestrial systems, novel contaminants, bioavailability, exposure data analysis, and uncertainty associated with exposure in wildlife risk assessments. Lastly, we identify areas related to exposure among terrestrial and semi-terrestrial organisms that warrant additional research. - Both biotic and abiotic factors determine chemical exposure for terrestrial vertebrates

  13. The impact assessment of anticancer drug imatinib on the feeding behavior of rotifers with an integrated perspective: Exposure, post-exposure and re-exposure.

    Science.gov (United States)

    Yan, Zhengyu; Yan, Kun; He, Xingliang; Liu, Yanhua; Zhang, Jie; Lopez Torres, Oscar; Guo, Ruixin; Chen, Jianqiu

    2017-10-01

    The anticancer drugs are getting increasing attention as an emerging contaminant in the aquatic environments. In the present study, feeding behavior of the rotifer Brachionus calyciflorus under the impact of anticancer drug imatinib was evaluated. Traditional toxicological studies usually focus on dose-effect relationship at a given exposure time, while ignore the possible impact after the exposure. Thus, how the impact varied in the post-exposure and re-exposure was also considered in the present study. The feeding depression of the rotifers was attributed to the increased concentration of imatinib. Although the filtration and ingestion rate of the rotifers recovered to a certain extent after the exposure, the significant feeding inhibition still persisted even if the exposure was ended. In the re-exposure period, the feeding behavior was less depressed than those of the exposure period, which implied that rotifers might develop a tolerance to the same toxics. The activities of acetylcholine esterase (AchE) and the levels of reactive oxygen species (ROS) in rotifers were also detected. Imatinib inhibited the activities of AchE in the exposure and re-exposure while ROS levels increased significantly in the re-exposure period. Our present study provided an integrated assessment the potential environmental risks of imatinib at a new perspective. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Comparing exposure zones by different exposure metrics using statistical parameters: contrast and precision.

    Science.gov (United States)

    Park, Ji Young; Ramachandran, Gurumurthy; Raynor, Peter C; Eberly, Lynn E; Olson, Greg

    2010-10-01

    Recently, the appropriateness of using the 'mass concentration' metric for ultrafine particles has been questioned and surface area (SA) or number concentration metrics has been proposed as alternatives. To assess the abilities of various exposure metrics to distinguish between different exposure zones in workplaces with nanoparticle aerosols, exposure concentrations were measured in preassigned 'high-' and 'low-'exposure zones in a restaurant, an aluminum die-casting factory, and a diesel engine laboratory using SA, number, and mass concentration metrics. Predetermined exposure classifications were compared by each metric using statistical parameters and concentration ratios that were calculated from the different exposure concentrations. In the restaurant, SA and fine particle number concentrations showed significant differences between the high- and low-exposure zones and they had higher contrast (the ratio of between-zone variance to the sum of the between-zone and within-zone variances) than mass concentrations. Mass concentrations did not show significant differences. In the die cast facility, concentrations of all metrics were significantly greater in the high zone than in the low zone. SA and fine particle number concentrations showed larger concentration ratios between the high and low zones and higher contrast than mass concentrations. None of the metrics were significantly different between the high- and low-exposure zones in the diesel engine laboratory. The SA and fine particle number concentrations appeared to be better at differentiating exposure zones and finding the particle generation sources in workplaces generating nanoparticles. Because the choice of an exposure metric has significant implications for epidemiologic studies and industrial hygiene practice, a multimetric sampling approach is recommended for nanoparticle exposure assessment.

  15. Nature of activities and natural, artificial, accidental exposures. Magnitude of these exposures

    International Nuclear Information System (INIS)

    Aurengo, A.

    2009-01-01

    The exposure to ionizing radiation (I.R.) is linked to radioelements of organism (9%), earth (12%), cosmic radiation (10%), radon (37%), atmospheric fallout ( nuclear tests 2.5% and industry 0.5%) and to medical procedures (29%). The natural exposure varies in France from 2.5 to 5 mSv by year. In some areas in the world it reaches several tens of mSv by year. The medical exposure is very heterogeneous and concerns particularly old people. For a same examination, the patients exposure varies in an important way ( sometimes from 1 to 10) according to the country, even in France. In France, 250 000 persons are occupationally exposed to ionizing radiation. Among these ones, the most of cases exceeded regulatory limits for exposure to IR concern the health sector. The accidental exposures are in relation with industrial activities (51%) research (20%) civil nuclear (13%) or military (5%) and medical activities (11%). The exposures and then the consequences are very variable, ranging from death to unapparent consequences. in the most of cases a human error is involved and these accidents could have been avoided through measures of prevention and training. (N.C.)

  16. Application of maximum radiation exposure values and monitoring of radiation exposure

    International Nuclear Information System (INIS)

    1993-01-01

    According to the Section 32 of the Radiation Act (592/91) the Finnish Centre for Radiation and Nuclear Safety gives instructions concerning the monitoring of the radiation exposure and the application of the dose limits in Finland. The principles to be applied to calculating the equivalent and the effective doses are presented in the guide. Also the detailed instructions on the application of the maximum exposure values for the radiation work and for the natural radiation as well as the instructions on the monitoring of the exposures are given. Quantities and units for assessing radiation exposure are presented in the appendix of the guide

  17. Smoke exposure at western wildfires.

    Science.gov (United States)

    Timothy E. Reinhardt; Roger D. Ottmar

    2000-01-01

    Smoke exposure measurements among firefighters at wildfires in the Western United States between 1992 and 1995 showed that altogether most exposures were not significant, between 3 and 5 percent of the shift-average exposures exceeded occupational exposure limits for carbon monoxide and respiratory irritants. Exposure to benzene and total suspended particulate was not...

  18. Virtual reality exposure therapy

    OpenAIRE

    Rothbaum, BO; Hodges, L; Kooper, R

    1997-01-01

    It has been proposed that virtual reality (VR) exposure may be an alternative to standard in vivo exposure. Virtual reality integrates real-time computer graphics, body tracking devices, visual displays, and other sensory input devices to immerse a participant in a computer- generated virtual environment. Virtual reality exposure is potentially an efficient and cost-effective treatment of anxiety disorders. VR exposure therapy reduced the fear of heights in the first control...

  19. Determinants of Dermal Exposure Relevant for Exposure Modelling in Regulatory Risk Assessment

    NARCIS (Netherlands)

    Marquart, J.; Brouwer, D.H.; Gijsbers, J.H.J.; Links, I.H.M.; Warren, N.; Hemmen, J.J. van

    2003-01-01

    Risk assessment of chemicals requires assessment of the exposure levels of workers. In the absence of adequate specific measured data, models are often used to estimate exposure levels. For dermal exposure only a few models exist, which are not validated externally. In the scope of a large European

  20. Mechanical Behavior of Castor-Oil-Based Advanced Polyurethane Functionalized with Glycidol and Siloxanes

    Science.gov (United States)

    Mathew, Aiswarea; Kurmvanshi, Surendra; Mohanty, Smita; Nayak, Sanjay K.

    2017-12-01

    Castor-oil-based polyurethane (PU), epoxy (glycidol) terminated polyurethane (EPU), and hydroxy terminated poly (dimethyl siloxane) (HTPDMS) modified EPU (EPDMS) were synthesized. The PU and EPU were synthesized with polyol:diisocyanate and polyol:diisocyanate:glycidol ratio of 1:1.2 and 1:3:3, respectively, whereas EPDMS was prepared by the incorporation of 5 wt.%, 10 wt.%, 20 wt.%, and 30 wt.% of HTPDMS into the EPU. The structural modification of EPDMS was confirmed by solid-state CP/MAS 13C and 29Si NMR spectroscopy. The results of a tensile test revealed that the EPDMS with 10 wt.% loading of HTPDMS (EPDMS10) exhibited considerable enhancement in the tensile strength and modulus. The scanning electron microscope analysis was performed to understand the increased phase heterogeneity of the samples.

  1. Exposure is not enough: suppressing stimuli from awareness can abolish the mere exposure effect.

    Directory of Open Access Journals (Sweden)

    Daniel de Zilva

    Full Text Available Passive exposure to neutral stimuli increases subsequent liking of those stimuli--the mere exposure effect. Because of the broad implications for understanding and controlling human preferences, the role of conscious awareness in mere exposure has received much attention. Previous studies have claimed that the mere exposure effect can occur without conscious awareness of the stimuli. In two experiments, we applied a technique new to the mere exposure literature, called continuous flash suppression, to expose stimuli for a controlled duration with and without awareness. To ensure the reliability of the awareness manipulation, awareness was monitored on a trial-by-trial basis. Our results show that under these conditions the mere exposure effect does not occur without conscious awareness. In contrast, only when participants were aware of the stimuli did exposure increase liking and recognition. Together these data are consistent with the idea that the mere exposure effect requires conscious awareness and has important implications for theories of memory and affect.

  2. Exposure is not enough: suppressing stimuli from awareness can abolish the mere exposure effect.

    Science.gov (United States)

    de Zilva, Daniel; Vu, Luke; Newell, Ben R; Pearson, Joel

    2013-01-01

    Passive exposure to neutral stimuli increases subsequent liking of those stimuli--the mere exposure effect. Because of the broad implications for understanding and controlling human preferences, the role of conscious awareness in mere exposure has received much attention. Previous studies have claimed that the mere exposure effect can occur without conscious awareness of the stimuli. In two experiments, we applied a technique new to the mere exposure literature, called continuous flash suppression, to expose stimuli for a controlled duration with and without awareness. To ensure the reliability of the awareness manipulation, awareness was monitored on a trial-by-trial basis. Our results show that under these conditions the mere exposure effect does not occur without conscious awareness. In contrast, only when participants were aware of the stimuli did exposure increase liking and recognition. Together these data are consistent with the idea that the mere exposure effect requires conscious awareness and has important implications for theories of memory and affect.

  3. Environmental radioactivity and radiation exposure

    International Nuclear Information System (INIS)

    1980-01-01

    In 1977 population exposure in the Federal Republic of Germany has not changed as compared to the previous years. The main share of the total exposure, nearly two thirds, is attributed to natural radioactive substances and cosmic radiation. The largest part (around 85%) of the artificial radiation exposure is caused by X-ray diagnostics. In comparison to this, radiation exposure from application of ionizing radiation in medical therapy, use of radioactive material in research and technology, or from nuclear facilities is small. As in the years before, population exposure caused by nuclear power plants and other nuclear facilities is distinctly less than 1% of the natural radiation exposure. This is also true for the average radiation exposure within a radius of 3 km around nuclear facilities. On the whole, the report makes clear that the total amount of artificial population exposure will substantially decrease only if one succeeds in reducing the high contribution to the radiation exposure caused by medical measures. (orig.) [de

  4. Post-Exposure Prophylaxis (PEP)

    Science.gov (United States)

    ... Child Transmission of HIV Post-Exposure Prophylaxis (PEP) Pre-Exposure Prophylaxis (PrEP) HIV Treatment HIV Treatment: The Basics Just ... to HIV frequently. Another HIV prevention method, called pre-exposure prophylaxis or PrEP, is when people at high risk ...

  5. Development of acute exposure guideline levels for airborne exposures to hazardous substances.

    Science.gov (United States)

    Krewski, Daniel; Bakshi, Kulbir; Garrett, Roger; Falke, Ernest; Rusch, George; Gaylor, David

    2004-04-01

    Hazardous substances can be released into the atmosphere due to industrial and transportation accidents, fires, tornadoes, earthquakes, and terrorists, thereby exposing workers and the nearby public to potential adverse health effects. Various enforceable guidelines have been set by regulatory agencies for worker and ambient air quality. However, these exposure levels generally are not applicable to rare lifetime acute exposures, which possibly could occur at high concentrations. Acute exposure guideline levels (AEGLs) provide estimates of concentrations for airborne exposures for an array of short durations that possibly could cause mild (AEGL-1), severe, irreversible, potentially disabling adverse health effects (AEGL-2), or life threatening effects (AEGL-3). These levels can be useful for emergency responders and planners in reducing or eliminating potential risks to the public. Procedures and methodologies for deriving AEGLs are reviewed in this paper that have been developed in the United States, with direct input from international representatives of OECD member-countries, by the National Advisory Committee for Acute Exposure Guidelines for Hazardous Substances and reviewed by the National Research Council. Techniques are discussed for the extrapolation of effects across different exposure durations. AEGLs provide a viable approach for assisting in the prevention, planning, and response to acute airborne exposures to toxic agents.

  6. Stimulus threat and exposure context modulate the effect of mere exposure on approach behaviors

    Directory of Open Access Journals (Sweden)

    Steven Young

    2016-11-01

    Full Text Available Mere-exposure research has found that initially neutral objects made familiar are preferred relative to novel objects. Recent work extends these preference judgments into the behavioral domain by illustrating that mere exposure prompts approach-oriented behavior toward familiar stimuli. However, no investigations have examined the effect of mere exposure on approach-oriented behavior toward threatening stimuli. The current work examines this issue and also explores how exposure context interacts with stimulus threat to influence behavioral tendencies. In two experiments participants were presented with both mere-exposed and novel stimuli and approach speed was assessed. In the first experiment, when stimulus threat was presented in a homogeneous format (i.e., participants viewed exclusively neutral or threatening stimuli, mere-exposure potentiated approach behaviors for both neutral and threatening stimuli. However, in the second experiment, in which stimulus threat was presented in a heterogeneous fashion (i.e., participants viewed both neutral and threatening stimuli, mere exposure facilitated approach only for initially neutral stimuli. These results suggest that mere-exposure effects on approach behaviors are highly context sensitive and depend on both stimulus valence and exposure context. Further implications of these findings for the mere-exposure literature are discussed.

  7. Synthesis and self-assembly of Chitosan-g-Polystyrene copolymer: A new route for the preparation of heavy metal nanoparticles

    KAUST Repository

    Francis, Raju S.; Baby, Deepa K.; Gnanou, Yves

    2015-01-01

    Amphiphilic graft copolymers made of a Chitosan (CS) backbone and three arm polystyrene (PS) grafts were prepared by "grafting onto" strategy using Toluene Diisocyanate. IR spectroscopy and SEC show the successful grafting process. SEM pictures

  8. Determinants of dermal exposure relevant for exposure modelling in regulatory risk assessment.

    Science.gov (United States)

    Marquart, J; Brouwer, D H; Gijsbers, J H J; Links, I H M; Warren, N; van Hemmen, J J

    2003-11-01

    Risk assessment of chemicals requires assessment of the exposure levels of workers. In the absence of adequate specific measured data, models are often used to estimate exposure levels. For dermal exposure only a few models exist, which are not validated externally. In the scope of a large European research programme, an analysis of potential dermal exposure determinants was made based on the available studies and models and on the expert judgement of the authors of this publication. Only a few potential determinants appear to have been studied in depth. Several studies have included clusters of determinants into vaguely defined parameters, such as 'task' or 'cleaning and maintenance of clothing'. Other studies include several highly correlated parameters, such as 'amount of product handled', 'duration of task' and 'area treated', and separation of these parameters to study their individual influence is not possible. However, based on the available information, a number of determinants could clearly be defined as proven or highly plausible determinants of dermal exposure in one or more exposure situation. This information was combined with expert judgement on the scientific plausibility of the influence of parameters that have not been extensively studied and on the possibilities to gather relevant information during a risk assessment process. The result of this effort is a list of determinants relevant for dermal exposure models in the scope of regulatory risk assessment. The determinants have been divided into the major categories 'substance and product characteristics', 'task done by the worker', 'process technique and equipment', 'exposure control measures', 'worker characteristics and habits' and 'area and situation'. To account for the complex nature of the dermal exposure processes, a further subdivision was made into the three major processes 'direct contact', 'surface contact' and 'deposition'.

  9. Occupational exposures. Annex H

    International Nuclear Information System (INIS)

    1982-01-01

    This Annex focuses on significant changes in the pattern of occupational exposure which have appeared since the 1972 and 1962 reports, and presents information on trends or particular causes of high exposures. A further objective is to clarify the reasons for which the Committee requires data on occupational exposure, and to suggest areas in which better data collection or analysis may be performed. Data are also reviewed on accidents involving the exposure of workers to substantial radiation doses.

  10. Non-medical exposures - Ethical concerns

    International Nuclear Information System (INIS)

    O'Reilly, G.

    2009-01-01

    The scope of the Medical Exposure Directive (MED), 97/43/Euratom (Council Directive 97/43/EURATOM, on the health protection of individuals against the dangers of ionising radiation in relation to medical exposures. OJ L 180 of 09.07.1997), is such that it includes not only those exposures which are part of the normal diagnosis and treatment of patients but also exposures for occupational health surveillance, health-screening programmes, research and medico-legal exposures. This is the first time that radiation protection legislation has tried to deal explicitly with the issue of medico-legal exposures in a European Directive. However, it has done so in the context of a Directive whose primary focus is the protection of patients undergoing diagnostic or therapeutic medical exposures. This may not be an appropriate framework for medico-legal exposures. In considering medico-legal exposures, a significant number of ethical considerations arise. The MED may not adequately take account of these matters and in fact may not be a suitable legal instrument for dealing with them. This paper looks specifically at the issues surrounding medico-legal exposures and considers whether or not the current system provides adequate protection for the individuals exposed. (authors)

  11. Evaluation of environmental radiation exposure

    International Nuclear Information System (INIS)

    Imai, Kazuhiko

    1974-01-01

    The environmental radiation exposure due to radioactive rare gases is most important both at the time of reactor accidents and also in the long-term normal operation of reactor plants. The exposure dose is usually calculated by means of computers. The procedure of the calculation on environmental exposure dose is divided in several consecutive steps. The calculational formulae frequently used and those proposed recently are given with the explanation on released radionuclides, release to the atmosphere, concentration in the atmosphere, β-ray exposure, γ-ray exposure, and calculation of long-term exposure dose. (Mori, K.)

  12. Natural radiation exposure indoors

    International Nuclear Information System (INIS)

    Brown, L.; Cliff, K.D.; Wrixon, A.D.

    1981-01-01

    A brief review is presented of the state of knowledge of indoor natural radiation exposure in the U.K. and the current survey work the N.R.P.B. is carrying out in this field. Discussion is limited in this instance to the improvement in estimation of population exposure and the identification of areas and circumstances in which high exposure occur, rather than the study of properties of a building and methods of building affecting exposure to radiation. (U.K.)

  13. Opinion of the scientific committee on consumer safety (SCCS)--2nd Revision of the safety of the use of poly(hexamethylene) biguanide hydrochloride or polyaminopropyl biguanide (PHMB) in cosmetic products.

    Science.gov (United States)

    Bernauer, Ulrike

    2015-12-01

    Conclusion of the opinion: On the basis of the data available, the SCCS concludes that Polyaminopropyl Biguanide (PHMB) is not safe for consumers when used as a preservative in cosmetic spray formulations and in all cosmetic products up to the maximum concentration of 0.3%. The safe use could be based on a lower use concentration and/or restrictions with regard to cosmetic products' categories. Dermal absorption studies on additional representative cosmetic formulations are needed. PHMB is used in a variety of applications other than cosmetics. General exposure data from sources others than cosmetics should be submitted for the assessment of the aggregate exposure of PHMB. Copyright © 2015. Published by Elsevier Inc.

  14. Dioxin Exposure Initiative

    Science.gov (United States)

    The Dioxin Exposure Initiative (DEI) is no longer active. This page contains a summary of the dioxin exposure initiative with illustrations, contact and background information.Originally supported by scientist Matthew Lorber, who retired in Mar 2017.

  15. Assessment of human exposures

    Energy Technology Data Exchange (ETDEWEB)

    Lebret, E. [RIVM-National Inst. of Public Health and Environmental Protection (Netherlands)

    1995-12-31

    This article describes some of the features of the assessment of human exposure to environmental pollutants in epidemiological studies. Since exposure assessment in air pollution epidemiology studies typically involve professionals from various backgrounds, interpretation of a concepts like `exposure` may vary. A brief descriptions is therefore given by way of introduction

  16. Assessment of human exposures

    Energy Technology Data Exchange (ETDEWEB)

    Lebret, E [RIVM-National Inst. of Public Health and Environmental Protection (Netherlands)

    1996-12-31

    This article describes some of the features of the assessment of human exposure to environmental pollutants in epidemiological studies. Since exposure assessment in air pollution epidemiology studies typically involve professionals from various backgrounds, interpretation of a concepts like `exposure` may vary. A brief descriptions is therefore given by way of introduction

  17. Development of a Job-Exposure Matrix (AsbJEM) to Estimate Occupational Exposure to Asbestos in Australia.

    Science.gov (United States)

    van Oyen, Svein C; Peters, Susan; Alfonso, Helman; Fritschi, Lin; de Klerk, Nicholas H; Reid, Alison; Franklin, Peter; Gordon, Len; Benke, Geza; Musk, Arthur W

    2015-07-01

    Occupational exposure data on asbestos are limited and poorly integrated in Australia so that estimates of disease risk and attribution of disease causation are usually calculated from data that are not specific for local conditions. To develop a job-exposure matrix (AsbJEM) to estimate occupational asbestos exposure levels in Australia, making optimal use of the available exposure data. A dossier of all available exposure data in Australia and information on industry practices and controls was provided to an expert panel consisting of three local industrial hygienists with thorough knowledge of local and international work practices. The expert panel estimated asbestos exposures for combinations of occupation, industry, and time period. Intensity and frequency grades were estimated to enable the calculation of annual exposure levels for each occupation-industry combination for each time period. Two indicators of asbestos exposure intensity (mode and peak) were used to account for different patterns of exposure between occupations. Additionally, the probable type of asbestos fibre was determined for each situation. Asbestos exposures were estimated for 537 combinations of 224 occupations and 60 industries for four time periods (1943-1966; 1967-1986; 1987-2003; ≥2004). Workers in the asbestos manufacturing, shipyard, and insulation industries were estimated to have had the highest average exposures. Up until 1986, 46 occupation-industry combinations were estimated to have had exposures exceeding the current Australian exposure standard of 0.1 f ml(-1). Over 90% of exposed occupations were considered to have had exposure to a mixture of asbestos varieties including crocidolite. The AsbJEM provides empirically based quantified estimates of asbestos exposure levels for Australian jobs since 1943. This exposure assessment application will contribute to improved understanding and prediction of asbestos-related diseases and attribution of disease causation. © The

  18. View point of medical exposure

    International Nuclear Information System (INIS)

    Akahane, Keiichi

    2008-01-01

    This text contains the following subjects. (1) Introduction, (2) Progress of medical examinations by radiation, (2-1) Decision of applying radiation, (2-2) Irradiation method, (2-3) Irradiation dose, (3) Exposure at medical examinations by radiation, (3-1) Dose to express the exposure, (3-2) Dose at medical exposure, (4) Types of medical examinations by radiation, (4-1) Radiation diagnosis, (4-2) Radiation therapy, (4-3) Nuclear medicine, (5) Radiation effects, (5-1) Types of radiation effect, (5-2) Effects of medical exposure, (6) Present status of medical examination by radiation, (6-1) Actual status of medical exposure, (6-2) Medical examinations by radiation in Japan, (7) Assessment of medical exposure, (7-1) Exposure dose, (7-2) Papers on radiation risk, and (7-3) Radiation protection. (K.Y.)

  19. Stimulus threat and exposure context modulate the effect of mere exposure on approach behaviors

    OpenAIRE

    Steven Young; Heather Claypool; Isaiah Jones

    2016-01-01

    Mere-exposure research has found that initially neutral objects made familiar are preferred relative to novel objects. Recent work extends these preference judgments into the behavioral domain by illustrating that mere exposure prompts approach-oriented behavior toward familiar stimuli. However, no investigations have examined the effect of mere exposure on approach-oriented behavior toward threatening stimuli. The current work examines this issue and also explores how exposure context intera...

  20. Vaporous Decontamination Methods: Potential Uses and Research Priorities for Chemical and Biological Contamination Control

    Science.gov (United States)

    2006-06-01

    over time. Ammonia gas is typically used to neutralise formaldehyde forming a white precipitate, hexamethylene- tetramine, which is then washed down...sulphite scrubbers DSTO-GD-0465 4 and a carbon bed to prevent any leakage of the ClO2 gas into the environment. The decontamination period (12...of ammonia gas) produces a broad-spectrum decontaminant against C agents [7]. However, initial studies have shown that the modified vaporous

  1. Poliuretanos obtenidos a partir de aceite de higuerilla modificado y poli-isocianatos de lisina: síntesis, propiedades mecánicas y térmicas y degradación in vitro

    Directory of Open Access Journals (Sweden)

    Manuel F. Valero

    2014-01-01

    Full Text Available Biodegradable polyurethanes (PUR were prepared from polyols derived from castor oil by transesterification of pentaerythritol-modified castor oil and lysine polyisocyanates (LDI and LTI. The polyurethanes obtained were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA, and dynamic mechanical thermal analysis (DMTA. The mechanical behavior of the polyurethanes was measured by Shore A hardness and tensile testing (stress-strain curves. The biodegradable nature of the material was determined by contact angle, water absorption tests, and in vitro degradation in PBS solution. This study aims to examine the effect of the structure and functionality of diisocyanate on the mechanical properties and in vitro degradation of the material. The results were compared with homologous materials obtained from isophorone diisocyanate (IPDI used in previous works. The objective was to evaluate candidate materials that can be potentially used in tissue engineering.

  2. Occupational Exposure to Pesticides With Occupational Sun Exposure Increases the Risk for Cutaneous Melanoma.

    Science.gov (United States)

    Fortes, Cristina; Mastroeni, Simona; Segatto M, Marjorie; Hohmann, Clarissa; Miligi, Lucia; Bakos, Lucio; Bonamigo, Renan

    2016-04-01

    The objective of the study was to examine the association between occupational exposure to pesticides and cutaneous melanoma, controlling for all possible confounders. A pooled analysis of two case-control studies was conducted in two different geographic areas (Italy and Brazil). Detailed pesticides exposure histories were obtained. Ever use of any pesticide was associated with a high risk of cutaneous melanoma (odds ratio 2.58; 95% confidence interval 1.18-5.65) in particular exposure to herbicides (glyphosate) and fungicides (mancozeb, maneb), after controlling for confounding factors. When subjects were exposed to both pesticides and occupational sun exposure, the risk increased even more (odds ratio 4.68; 95% confidence interval 1.29-17.0). The study suggests an augmented risk of cutaneous melanoma among subjects with exposure to pesticides, in particular among those exposed to occupational sun exposure.

  3. Occupational risk and lifetime exposure

    International Nuclear Information System (INIS)

    Lapp, R.E.

    1991-01-01

    Any lowering of annual radiation limits for occupational exposure should be based on industry experience with lifetime doses and not on a worst case career exposure of 47 years. Two decades of experience show a lifetime accumulation of less than 1.5 rem for workers with measurable exposure. This is 5% of the normal lifetime exposure of Americans to natural and medical radiation. Any epidemiology of the US nuclear power workforce's two decade long exposure would have to focus on excess leukemia. Application of the Hiroshima and Nagasaki cancer mortality shows that too few leukemias would be expressed to permit a feasible epidemiology. Ionizing radiation appears to be a mild carcinogen as compared to physical and chemical agents presented in the occupational environment. A realistic factor in determining any change in occupational exposure limits for ionizing radiation should take into account the past performance of the licensee and potential health effects applicable to the workplace. Specifically, the lifetime exposure data for workers at nuclear power plants and naval shipyards should be considered. The nuclear industry and the US Navy have detailed data on the annual exposure of workers with a combined collective exposure approaching 1 million worker-rem. The lifetime dose for naval personnel and shipyard workers averages 1.1 rem J 1990. Shipyard workers have an annual dose of 0.28 rem per work-year and a mean exposure time of 4.4 years. The data apply to workers with measurable dose

  4. The Mere Exposure Instruction Effect.

    Science.gov (United States)

    Van Dessel, Pieter; Mertens, Gaëtan; Smith, Colin Tucker; De Houwer, Jan

    2017-09-01

    The mere exposure effect refers to the well-established finding that people evaluate a stimulus more positively after repeated exposure to that stimulus. We investigated whether a change in stimulus evaluation can occur also when participants are not repeatedly exposed to a stimulus, but are merely instructed that one stimulus will occur frequently and another stimulus will occur infrequently. We report seven experiments showing that (1) mere exposure instructions influence implicit stimulus evaluations as measured with an Implicit Association Test (IAT), personalized Implicit Association Test (pIAT), or Affect Misattribution Procedure (AMP), but not with an Evaluative Priming Task (EPT), (2) mere exposure instructions influence explicit evaluations, and (3) the instruction effect depends on participants' memory of which stimulus will be presented more frequently. We discuss how these findings inform us about the boundary conditions of mere exposure instruction effects, as well as the mental processes that underlie mere exposure and mere exposure instruction effects.

  5. Exposure Factors Resources: Contrasting EPA’s Exposure Factors Handbook with International Sources (Journal Article)

    Science.gov (United States)

    Efforts to compile and standardize exposure human factors have resulted in the development of a variety of resources available to the scientific community. For example, the U.S. EPA developed the Exposure Factors Handbook and Child-specific Exposure Factors Handbook to promote c...

  6. Monitoring of radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-02-01

    The guide specifies the requirements for the monitoring of radiation exposure in instances where radiation is used. In addition to workers, the guide covers students, apprentices and visitors. The guide shall also apply to exposure from natural radiation. However, the monitoring of radiation exposure in nuclear power plants is dealt with in YVL Guide 7.10 and 7.11. The guide defines the concepts relevant to the monitoring of radiation exposure and provides guidelines for determining the necessity of monitoring and subsequently arranging such in different operations. In addition, the guide specifies the criteria for the approval and regulatory control of the dosimetric service.

  7. Monitoring of radiation exposure

    International Nuclear Information System (INIS)

    2000-02-01

    The guide specifies the requirements for the monitoring of radiation exposure in instances where radiation is used. In addition to workers, the guide covers students, apprentices and visitors. The guide shall also apply to exposure from natural radiation. However, the monitoring of radiation exposure in nuclear power plants is dealt with in YVL Guide 7.10 and 7.11. The guide defines the concepts relevant to the monitoring of radiation exposure and provides guidelines for determining the necessity of monitoring and subsequently arranging such in different operations. In addition, the guide specifies the criteria for the approval and regulatory control of the dosimetric service

  8. A paediatric X-ray exposure chart

    Energy Technology Data Exchange (ETDEWEB)

    Knight, Stephen P, E-mail: stephen.knight@health.qld.gov.au [Department of Medical Imaging, Royal Children' s Hospital, Brisbane, Queensland (Australia)

    2014-09-15

    The aim of this review was to develop a radiographic optimisation strategy to make use of digital radiography (DR) and needle phosphor computerised radiography (CR) detectors, in order to lower radiation dose and improve image quality for paediatrics. This review was based on evidence-based practice, of which a component was a review of the relevant literature. The resulting exposure chart was developed with two distinct groups of exposure optimisation strategies – body exposures (for head, trunk, humerus, femur) and distal extremity exposures (elbow to finger, knee to toe). Exposure variables manipulated included kilovoltage peak (kVp), target detector exposure and milli-ampere-seconds (mAs), automatic exposure control (AEC), additional beam filtration, and use of antiscatter grid. Mean dose area product (DAP) reductions of up to 83% for anterior–posterior (AP)/posterior–anterior (PA) abdomen projections were recorded postoptimisation due to manipulation of multiple-exposure variables. For body exposures, the target EI and detector exposure, and thus the required mAs were typically 20% less postoptimisation. Image quality for some distal extremity exposures was improved by lowering kVp and increasing mAs around constant entrance skin dose. It is recommended that purchasing digital X-ray equipment with high detective quantum efficiency detectors, and then optimising the exposure chart for use with these detectors is of high importance for sites performing paediatric imaging. Multiple-exposure variables may need to be manipulated to achieve optimal outcomes.

  9. Estimating Contact Exposure in Football Using the Head Impact Exposure Estimate.

    Science.gov (United States)

    Kerr, Zachary Y; Littleton, Ashley C; Cox, Leah M; DeFreese, J D; Varangis, Eleanna; Lynall, Robert C; Schmidt, Julianne D; Marshall, Stephen W; Guskiewicz, Kevin M

    2015-07-15

    Over the past decade, there has been significant debate regarding the effect of cumulative subconcussive head impacts on short and long-term neurological impairment. This debate remains unresolved, because valid epidemiological estimates of athletes' total contact exposure are lacking. We present a measure to estimate the total hours of contact exposure in football over the majority of an athlete's lifespan. Through a structured oral interview, former football players provided information related to primary position played and participation in games and practice contacts during the pre-season, regular season, and post-season of each year of their high school, college, and professional football careers. Spring football for college was also included. We calculated contact exposure estimates for 64 former football players (n = 32 college football only, n = 32 professional and college football). The head impact exposure estimate (HIEE) discriminated between individuals who stopped after college football, and individuals who played professional football (p < 0.001). The HIEE measure was independent of concussion history (p = 0.82). Estimating total hours of contact exposure may allow for the detection of differences between individuals with variation in subconcussive impacts, regardless of concussion history. This measure is valuable for the surveillance of subconcussive impacts and their associated potential negative effects.

  10. Using Information on Exposure to Characterizing Risks to Human Health from Concurrent Exposures to Multiple Chemicals

    NARCIS (Netherlands)

    Mr Price, PSP

    2012-01-01

    This thesis explores the concept of using exposure information to understand, organize, and manage the risks associated with cumulative exposures to chemicals (exposures to multiple chemicals from multiple sources). The issue of cumulative exposures was identified in more than 30 years ago, but in

  11. Influence of gamma radiation on the crosslinking properties of oligo-butadiene-base polyurethane elastomers

    International Nuclear Information System (INIS)

    Dedgaonkar, V.G.

    1994-01-01

    Liquid oligo-butadiene-base diol was cured by gammas when a diisocyanate and a triol were present. The NCO/OH ratio was at unity. Radiation brought about crosslink networks through urethane linkages and among polybutadiene segments. (author). 5 refs., 1 tab

  12. Characterisation of Rapeseed Oil Based Resins Using Infrared and ...

    African Journals Online (AJOL)

    The hydroxylated chemical structure was crosslinked using methylene-pphenyl diisocyanate to produce a thermoset rapeseed oil resin. The cross linking process was monitored in situ using the Attenuated Total Internal Reflectance Fourier Transform-Infrared spectroscopy and the thermogravimetric analysis techniques.

  13. Electrospun Polyurethane Fibers for Absorption of Volatile Organic Compounds from Air

    NARCIS (Netherlands)

    Scholten, E.; Bromberg, L.; Rutledge, G.C.; Hatton, T.A.

    2011-01-01

    Electrospun polyurethane fibers for removal of volatile organic compounds (VOC) from air with rapid VOC absorption and desorption have been developed. Polyurethanes based on 4,4-methylenebis(phenylisocyanate) (MDI) and aliphatic isophorone diisocyanate as the hard segments and butanediol and

  14. Development of retrospective quantitative and qualitative job-exposure matrices for exposures at a beryllium processing facility.

    Science.gov (United States)

    Couch, James R; Petersen, Martin; Rice, Carol; Schubauer-Berigan, Mary K

    2011-05-01

    To construct a job-exposure matrix (JEM) for an Ohio beryllium processing facility between 1953 and 2006 and to evaluate temporal changes in airborne beryllium exposures. Quantitative area- and breathing-zone-based exposure measurements of airborne beryllium were made between 1953 and 2006 and used by plant personnel to estimate daily weighted average (DWA) exposure concentrations for sampled departments and operations. These DWA measurements were used to create a JEM with 18 exposure metrics, which was linked to the plant cohort consisting of 18,568 unique job, department and year combinations. The exposure metrics ranged from quantitative metrics (annual arithmetic/geometric average DWA exposures, maximum DWA and peak exposures) to descriptive qualitative metrics (chemical beryllium species and physical form) to qualitative assignment of exposure to other risk factors (yes/no). Twelve collapsed job titles with long-term consistent industrial hygiene samples were evaluated using regression analysis for time trends in DWA estimates. Annual arithmetic mean DWA estimates (overall plant-wide exposures including administration, non-production, and production estimates) for the data by decade ranged from a high of 1.39 μg/m(3) in the 1950s to a low of 0.33 μg/m(3) in the 2000s. Of the 12 jobs evaluated for temporal trend, the average arithmetic DWA mean was 2.46 μg/m(3) and the average geometric mean DWA was 1.53 μg/m(3). After the DWA calculations were log-transformed, 11 of the 12 had a statistically significant (p < 0.05) decrease in reported exposure over time. The constructed JEM successfully differentiated beryllium exposures across jobs and over time. This is the only quantitative JEM containing exposure estimates (average and peak) for the entire plant history.

  15. Radiation camera exposure control

    International Nuclear Information System (INIS)

    Martone, R.J.; Yarsawich, M.; Wolczek, W.

    1976-01-01

    A system and method for governing the exposure of an image generated by a radiation camera to an image sensing camera is disclosed. The exposure is terminated in response to the accumulation of a predetermined quantity of radiation, defining a radiation density, occurring in a predetermined area. An index is produced which represents the value of that quantity of radiation whose accumulation causes the exposure termination. The value of the predetermined radiation quantity represented by the index is sensed so that the radiation camera image intensity can be calibrated to compensate for changes in exposure amounts due to desired variations in radiation density of the exposure, to maintain the detectability of the image by the image sensing camera notwithstanding such variations. Provision is also made for calibrating the image intensity in accordance with the sensitivity of the image sensing camera, and for locating the index for maintaining its detectability and causing the proper centering of the radiation camera image

  16. Long- and short-term exposure to PM2.5 and mortality: using novel exposure models.

    Science.gov (United States)

    Kloog, Itai; Ridgway, Bill; Koutrakis, Petros; Coull, Brent A; Schwartz, Joel D

    2013-07-01

    Many studies have reported associations between ambient particulate matter (PM) and adverse health effects, focused on either short-term (acute) or long-term (chronic) PM exposures. For chronic effects, the studied cohorts have rarely been representative of the population. We present a novel exposure model combining satellite aerosol optical depth and land-use data to investigate both the long- and short-term effects of PM2.5 exposures on population mortality in Massachusetts, United States, for the years 2000-2008. All deaths were geocoded. We performed two separate analyses: a time-series analysis (for short-term exposure) where counts in each geographic grid cell were regressed against cell-specific short-term PM2.5 exposure, temperature, socioeconomic data, lung cancer rates (as a surrogate for smoking), and a spline of time (to control for season and trends). In addition, for long-term exposure, we performed a relative incidence analysis using two long-term exposure metrics: regional 10 × 10 km PM2.5 predictions and local deviations from the cell average based on land use within 50 m of the residence. We tested whether these predicted the proportion of deaths from PM-related causes (cardiovascular and respiratory diseases). For short-term exposure, we found that for every 10-µg/m increase in PM 2.5 exposure there was a 2.8% increase in PM-related mortality (95% confidence interval [CI] = 2.0-3.5). For the long-term exposure at the grid cell level, we found an odds ratio (OR) for every 10-µg/m increase in long-term PM2.5 exposure of 1.6 (CI = 1.5-1.8) for particle-related diseases. Local PM2.5 had an OR of 1.4 (CI = 1.3-1.5), which was independent of and additive to the grid cell effect. We have developed a novel PM2.5 exposure model based on remote sensing data to assess both short- and long-term human exposures. Our approach allows us to gain spatial resolution in acute effects and an assessment of long-term effects in the entire population rather than a

  17. Effect of the average soft-segment length on the morphology and properties of segmented polyurethane nanocomposites

    International Nuclear Information System (INIS)

    Finnigan, Bradley; Halley, Peter; Jack, Kevin; McDowell, Alasdair; Truss, Rowan; Casey, Phil; Knott, Robert; Martin, Darren

    2006-01-01

    Two organically modified layered silicates (with small and large diameters) were incorporated into three segmented polyurethanes with various degrees of microphase separation. Microphase separation increased with the molecular weight of the poly(hexamethylene oxide) soft segment. The molecular weight of the soft segment did not influence the amount of polyurethane intercalating the interlayer spacing. Small-angle neutron scattering and differential scanning calorimetry data indicated that the layered silicates did not affect the microphase morphology of any host polymer, regardless of the particle diameter. The stiffness enhancement on filler addition increased as the microphase separation of the polyurethane decreased, presumably because a greater number of urethane linkages were available to interact with the filler. For comparison, the small nanofiller was introduced into a polyurethane with a poly(tetramethylene oxide) soft segment, and a significant increase in the tensile strength and a sharper upturn in the stress-strain curve resulted. No such improvement occurred in the host polymers with poly(hexamethylene oxide) soft segments. It is proposed that the nanocomposite containing the more hydrophilic and mobile poly(tetramethylene oxide) soft segment is capable of greater secondary bonding between the polyurethane chains and the organosilicate surface, resulting in improved stress transfer to the filler and reduced molecular slippage.

  18. The Australian Work Exposures Study: prevalence of occupational exposure to diesel engine exhaust.

    Science.gov (United States)

    Peters, Susan; Carey, Renee N; Driscoll, Timothy R; Glass, Deborah C; Benke, Geza; Reid, Alison; Fritschi, Lin

    2015-06-01

    Diesel engines are widely used in occupational settings. Diesel exhaust has been classified as a lung carcinogen, but data on number of workers exposed to different levels of diesel exhaust are not available in Australia. The aim of this study was to estimate the current prevalence of exposure to diesel engine exhaust in Australian workplaces. A cross-sectional survey of Australian males and females (18-65 years old) in current paid employment was undertaken. Information about the respondents' current job and various demographic factors was collected in a telephone interview using the web-based tool OccIDEAS. Semi-quantitative occupational exposure levels to diesel exhaust were assigned using programmed decision rules and numbers of workers exposed in Australia in 2011 were estimated. We defined substantial exposure as exposed at a medium or high level, for at least 5h per week. Substantial occupational exposure to diesel exhaust was experienced by 13.4% of the respondents in their current job. Exposure prevalence varied across states, ranging from 6.4% in the Australian Capital Territory to 17.0% in Western Australia. Exposures occurred mainly in the agricultural, mining, transport and construction industries, and among mechanics. Men (20.4%) were more often exposed than women (4.7%). Extrapolation to the total working population indicated that 13.8% (95% confidence interval 10.0-20.4) of the 2011 Australian workforce were estimated to be substantially exposed to diesel exhaust, and 1.8% of the workers were estimated to experience high levels of exposures in their current job. About 1.2 million Australian workers were estimated to have been exposed to diesel exhaust in their workplace in 2011. This is the first study to describe the prevalence of occupational diesel exhaust exposure in Australia and will enable estimation of the number of lung cancers attributable to diesel exhaust exposure in the workplace. © The Author 2015. Published by Oxford University Press

  19. Perinatal bisphenol A exposure and adult glucose homeostasis: identifying critical windows of exposure.

    Directory of Open Access Journals (Sweden)

    Jingli Liu

    Full Text Available Bisphenol A (BPA is a widespread endocrine-disrupting chemical used as the building block for polycarbonate plastics. Epidemiological evidence has correlated BPA exposure with higher risk of heart disease and type 2 diabetes. However, it remains unknown whether there are critical windows of susceptibility to BPA exposure on the development of dysglycemia. This study was an attempt to investigate the critical windows and the long-term consequences of perinatal exposure to BPA on glucose homeostasis. Pregnant mice were given either vehicle or BPA (100 µg/kg/day at different time of perinatal stage: 1 on days 1-6 of pregnancy (P1-P6, preimplantation exposure; 2 from day 6 of pregnancy until postnatal day (PND 0 (P6-PND0, fetal exposure; 3 from lactation until weaning (PND0-PND21, neonatal exposure; and 4 from day 6 of gestation until weaning (P6-PND21, fetal and neonatal exposure. At 3, 6 and 8 months of age, offspring in each group were challenged with glucose and insulin tolerance tests. Then islet morphometry and β-cell function were measured. The glucose homeostasis was impaired in P6-PND0 mice from 3 to 6 months of age, and this continued to 8 months in males, but not females. While in PND0-PND21 and P6-PND21 BPA-treated groups, only the 3-month-old male offspring developed glucose intolerance. Moreover, at the age of 3 months, perinatal exposure to BPA resulted in the increase of β-cell mass mainly due to the coordinate changes in cell replication, neogenesis, and apoptosis. The alterations of insulin secretion and insulin sensitivity, rather than β-cell mass, were consistent with the development of glucose intolerance. Our findings suggest that BPA may contribute to metabolic disorders relevant to glucose homeostasis and the effects of BPA were dose, sex, and time-dependent. Fetal development stage may be the critical window of susceptibility to BPA exposure.

  20. Exposure of healthy subjects with emissions from a gas metal arc welding process: part 1--exposure technique and external exposure.

    Science.gov (United States)

    Brand, P; Havlicek, P; Steiners, M; Holzinger, K; Reisgen, U; Kraus, T; Gube, M

    2013-01-01

    Studies concerning welding fume-related adverse health effects in welders are hampered by the heterogeneity of workplace situations, resulting in complex and non-standardized exposure conditions. In order to carry out welding fume exposure studies under controlled and standardized conditions, the Aachen Workplace Simulation Laboratory was developed. This laboratory consists of an emission room, in which welding fume is produced, and an exposure room in which human subjects are exposed to these fumes. Both rooms are connected by a ventilation system which allows the welding fume concentration to be regulated. Particle mass concentration was measured with a TEOM microbalance and the particle number-size distribution using a Grimm SMPS device. In a study, which is the subject of this paper, it has been shown that welding fume concentration can easily be regulated between 1 and about 3 mg m(-3). The chosen concentration can be kept constant for more than 8 h. However, transport of the particles from the emission room into the exposure room leads to a change in particle size distribution, which is probably due to coagulation of the fraction of smallest particles. The Aachen Workplace Simulation Laboratory is suitable for controlled exposure studies with human subjects.

  1. The validated sun exposure questionnaire

    DEFF Research Database (Denmark)

    Køster, B; Søndergaard, J; Nielsen, J B

    2017-01-01

    Few questionnaires used in monitoring sun-related behavior have been tested for validity. We established criteria validity of a developed questionnaire for monitoring population sun-related behavior. During May-August 2013, 664 Danes wore a personal electronic UV-dosimeter for one week...... that measured the outdoor time and dose of erythemal UVR exposure. In the following week, they answered a questionnaire on their sun-related behavior in the measurement week. Outdoor time measured by dosimetry correlated strongly with both outdoor time and the developed exposure scale measured...... in the questionnaire. Exposure measured in SED by dosimetry correlated strongly with the exposure scale. In a linear regression model of UVR (SED) received, 41 percent of the variation was explained by skin type, age, week of participation and the exposure scale, with the exposure scale as the main contributor...

  2. Benzene exposures in urban areas

    International Nuclear Information System (INIS)

    Valerio, F.; Pala, M.; Cipolla, M.; Stella, A.

    2001-01-01

    Benzene exposures in urban areas were reviewed. Available data confirm that both in USA and Europe, benzene concentrations measured by fixed outdoor monitoring stations underestimate personal exposures of urban residents. Indoor sources, passive smoke and the high exposures during commuting time may explain this difference. Measures in European towns confirm that very frequently mean daily personal exposures to benzene exceed 10 μg/m 3 , current European air quality guideline for this carcinogenic compound [it

  3. Existing Default Values and Recommendations for Exposure Assessment - A Nordic Exposure Group Project 2011

    DEFF Research Database (Denmark)

    Höglund, Lena; Räisänen, Jouni; Hämäläinen, Anne-Maija

    range of more or less well-documented values originating from many different sources. The purpose of this report is to give an overview and to evaluate exposure factors that are currently used by the authorities and industry in the exposure assessments for both adults (occupational and consumer exposure......) and children in relation to REACH. Another important purpose of the report is to contribute towards a further harmonisation of exposure factors by giving recommendations of most valid and representative defaults. These recommendations can be used besides REACH also in biocide's and plant protection product...

  4. Sound Exposure of Symphony Orchestra Musicians

    DEFF Research Database (Denmark)

    Schmidt, Jesper Hvass; Pedersen, Ellen Raben; Juhl, Peter Møller

    2011-01-01

    dBA and their left ear was exposed 4.6 dB more than the right ear. Percussionists were exposed to high sound peaks >115 dBC but less continuous sound exposure was observed in this group. Musicians were exposed up to LAeq8h of 92 dB and a majority of musicians were exposed to sound levels exceeding......Background: Assessment of sound exposure by noise dosimetry can be challenging especially when measuring the exposure of classical orchestra musicians where sound originate from many different instruments. A new measurement method of bilateral sound exposure of classical musicians was developed...... and used to characterize sound exposure of the left and right ear simultaneously in two different symphony orchestras.Objectives: To measure binaural sound exposure of professional classical musicians and to identify possible exposure risk factors of specific musicians.Methods: Sound exposure was measured...

  5. The sources of radiation exposure

    International Nuclear Information System (INIS)

    Bennett, B.G.

    1992-01-01

    Radiation protection of workers and of members of the public requires an assessment of the various sources of exposure, their variations in time or under specific conditions or circumstances, and the possibilities for control or limitation. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has evaluated the various components of natural and man-made sources in some detail. Natural exposures form the largest component of radiation exposure of man. Variability in exposures depends on elevation, the concentrations of radionuclides in soil, food and water, the composition of building materials and the susceptibility of indoor spaces to radon build-up. Man-made sources have included exposures to fallout from atmospheric nuclear testing and discharged from nuclear fuel cycle installations in routine operations or in accidents. The other main source of radiation exposures of individuals is in medical diagnostic examinations and therapeutic treatments. (author)

  6. Assessment of Human Exposure to ENMs.

    Science.gov (United States)

    Jiménez, Araceli Sánchez; van Tongeren, Martie

    2017-01-01

    Human exposure assessment of engineered nanomaterials (ENMs) is hampered, among other factors, by the difficulty to differentiate ENM from other nanomaterials (incidental to processes or naturally occurring) and the lack of a single metric that can be used for health risk assessment. It is important that the exposure assessment is carried out throughout the entire life-cycle as releases can occur at the different stages of the product life-cycle, from the synthesis, manufacture of the nano-enable product (occupational exposure) to the professional and consumer use of nano-enabled product (consumer exposure) and at the end of life.Occupational exposure surveys should follow a tiered approach, increasing in complexity in terms of instruments used and sampling strategy applied with higher tiers in order tailor the exposure assessment to the specific materials used and workplace exposure scenarios and to reduce uncertainty in assessment of exposure. Assessment of consumer exposure and of releases from end-of-life processes currently relies on release testing of nano-enabled products in laboratory settings.

  7. Reconstructing exposures from biomarkers using exposure-pharmacokinetic modeling--A case study with carbaryl.

    Science.gov (United States)

    Brown, Kathleen; Phillips, Martin; Grulke, Christopher; Yoon, Miyoung; Young, Bruce; McDougall, Robin; Leonard, Jeremy; Lu, Jingtao; Lefew, William; Tan, Yu-Mei

    2015-12-01

    Sources of uncertainty involved in exposure reconstruction for short half-life chemicals were characterized using computational models that link external exposures to biomarkers. Using carbaryl as an example, an exposure model, the Cumulative and Aggregate Risk Evaluation System (CARES), was used to generate time-concentration profiles for 500 virtual individuals exposed to carbaryl. These exposure profiles were used as inputs into a physiologically based pharmacokinetic (PBPK) model to predict urinary biomarker concentrations. These matching dietary intake levels and biomarker concentrations were used to (1) compare three reverse dosimetry approaches based on their ability to predict the central tendency of the intake dose distribution; and (2) identify parameters necessary for a more accurate exposure reconstruction. This study illustrates the trade-offs between using non-iterative reverse dosimetry methods that are fast, less precise and iterative methods that are slow, more precise. This study also intimates the necessity of including urine flow rate and elapsed time between last dose and urine sampling as part of the biomarker sampling collection for better interpretation of urinary biomarker data of short biological half-life chemicals. Resolution of these critical data gaps can allow exposure reconstruction methods to better predict population-level intake doses from large biomonitoring studies. Published by Elsevier Inc.

  8. Radiation exposure during ureteroscopy

    International Nuclear Information System (INIS)

    Bagley, D.H.; Cubler-Goodman, A.

    1990-01-01

    Use of fluoroscopy during ureteroscopy increases the risk of radiation exposure to the urologist and patient. Radiation entrance dosages were measured at skin level in 37 patients, and at the neck, trunk and finger of the urologist, and neck and trunk of the circulating nurse. Radiation exposure time was measured in 79 patients, and was related to the purpose of the procedure and the type of ureteroscope used, whether rigid or flexible. Exposure could be minimized by decreasing the fluoroscopy time. A portable C-arm fluoroscopy unit with electronic imaging and last image hold mode should be used to minimize exposure time. Lead aprons and thyroid shields should be used by the urologist and other personnel in the endoscopy room

  9. Exposures to natural radiation in Switzerland

    International Nuclear Information System (INIS)

    Murith, Ch.; Gurtner, A.

    1999-01-01

    The exposure of human beings to ionising radiation from natural sources is a continuing and inescapable feature of life on earth. There are two main sources that contribute to this exposure: high-energy cosmic-ray particles incident to the earth's atmosphere and radioactive nuclides that originated in the earth's crust and are present everywhere in the environment, including human body itself. Both external and internal exposures to humans arise from these sources. Exposures to natural radiation sources in Switzerland and some of their variations are here summarised and the resulting effective doses are compared to those from man-made sources exposures. It results that the natural background exposures are more significant for the population than most exposures to man-made sources. (authors)

  10. Population exposure to ultraviolet radiation in Finland 1920-1995: Exposure trends and a time-series analysis of exposure and cutaneous melanoma incidence

    International Nuclear Information System (INIS)

    Kojo, Katja; Jansen, Christer T.; Nybom, Pia; Huurto, Laura; Laihia, Jarmo; Ilus, Taina; Auvinen, Anssi

    2006-01-01

    Ultraviolet radiation (UVR) is the principal cause of cutaneous malignant melanoma (CMM). However, the relation between CMM and UVR exposure is not clear. We present the trends of population exposure to UVR and conduct a time-series analysis of the relation between UVR exposure and incidence of CMM. Data on CMM incidence were obtained from the Finnish Cancer Registry. Clothing coverage of the body was scored from archival photographs and the proportion of uncovered skin was used as a measure of solar exposure. Information on the number of sunny resort holidays, duration of annual holidays, and sunscreen sales were obtained from various sources. Exposed skin area doubled from 1920 to 1985. The average duration of annual holidays increased 30-fold. The number of sunny resort holidays and the sales of sunscreens increased rapidly from 1980. CMM was most strongly associated with solar exposure of 5-19 years earlier. There is a considerable decrease in clothing coverage during the 20th century. UVR exposure preceding CMM occurrence 4 years or less does not appear relevant, whereas the period 5-19 years prior to CMM occurrence might be the most relevant period. However, findings of ecological studies may not be applicable at the individual level

  11. Chelation in metal intoxication. VIII. Removal of chromium from organs of potassium chromate administered rats.

    Science.gov (United States)

    Behari, J R; Tandon, S K

    1980-03-01

    Some polyaminocarboxylic acids were examined for their ability to mobilize chromium from certain vital organs, their subcellular fractions, and blood cells of potassium chromate administered rats. Hexamethylene 1,6-diamino tetraacetic acid (TDTA), triethylene tetramine hexaacetic acid (TTHA), and ethylene diamine di (O-hydroxylphenyl acetic acid) (EDDHA) may be useful in preventing or reducing chromate toxicity. No definite relationship could be observed between the structure of the chelating agents and their chromium-removing capacity.

  12. Risk factors precipitating exacerbations in adult asthma patients ...

    African Journals Online (AJOL)

    one-third of the direct care costs of asthma are attributable to ED visits ... The setting for this study was the emergency unit, the primary health clinic and the asthma .... diisocyanate or when they were employed in the pharmaceutical, plastics or ...

  13. Meniscal tissue regeneration in porous 50/50 copoly(L-lactide/epsilon-caprolactone) implants

    NARCIS (Netherlands)

    de Groot, J. H.; Zijlstra, F. M.; Kuipers, HW; Pennings, A. J.; Veth, RPH; Jansen, HWB

    Porous materials of a high-molecular-weight 50/50 copolymer of L-lactide and epsilon-caprolactone with different compression moduli were used for meniscal repair. In contrast to the previously used 4,4'-diphenylmethane and 1,6-trans-cyclohexane diisocyanates containing polyurethanes, degradation

  14. Characterization of polycaprolactone and starch blends for potential ...

    African Journals Online (AJOL)

    Thermally blending starch and polycaprolactone with the compatibilizer methylenediphenyl diisocyanate (MDI) distributed in the polyester phase had been previously confirmed to enhance the mechanical properties and interface between the two phases of the blends. In this study, blends of polycaprolactone with various ...

  15. Characterization studies of lower and non-TDI polyurethane encapsulants

    International Nuclear Information System (INIS)

    Wilson, M.H.

    1993-09-01

    Polyurethane prepolymers containing toluene diisocyanate (TDI) are used within the Nuclear Weapons complex for many adhesive and encapsulation applications. As part of a program for minimizing hazards to workers and the environment, TDI will be eliminated. This report presents evaluation of alternative encapsulants

  16. Ability to Discriminate Between Sustainable and Unsustainable Heat Stress Exposures-Part 1: WBGT Exposure Limits.

    Science.gov (United States)

    Garzón-Villalba, Ximena P; Wu, Yougui; Ashley, Candi D; Bernard, Thomas E

    2017-07-01

    Heat stress exposure limits based on wet-bulb globe temperature (WBGT) were designed to limit exposures to those that could be sustained for an 8-h day using limited data from Lind in the 1960s. In general, Sustainable exposures are heat stress levels at which thermal equilibrium can be achieved, and Unsustainable exposures occur when there is a steady increase in core temperature. This paper addresses the ability of the ACGIH® Threshold Limit Value (TLV®) to differentiate between Sustainable and Unsustainable heat exposures, to propose alternative occupational exposure limits, and ask whether an adjustment for body surface area improves the exposure decision. Two progressive heat stress studies provided data on 176 trials with 352 pairs of Sustainable and Unsustainable exposures over a range of relative humidities and metabolic rates using 29 participants wearing woven cotton clothing. To assess the discrimination ability of the TLV, the exposure metric was the difference between the observed WBGT and the TLV adjusted for metabolic rate. Conditional logistic regression models and receiver operating characteristic curves (ROC) along with ROC's area under the curve (AUC) were used. Four alternative models for an occupational exposure limit were also developed and compared to the TLV. For the TLV, the odds ratio (OR) for Unsustainable was 2.5 per 1°C-WBGT [confidence interval (CI) 2.12-2.88]. The AUC for the TLV was 0.85 (CI 0.81-0.89). For the alternative models, the ORs were also about 2.5/°C-WBGT, with AUCs between 0.84 and 0.88, which were significantly different from the TLV's AUC but have little practical difference. This study (1) confirmed that the TLV is appropriate for heat stress screening; (2) demonstrated the TLV's discrimination accuracy with an ROC AUC of 0.85; and (3) established the OR of 2.5/°C-WBGT for unsustainable exposures. The TLV has high sensitivity, but its specificity is very low, which is protective. There were no important

  17. AirPEx. Air Pollution Exposure Model

    Energy Technology Data Exchange (ETDEWEB)

    Freijer, J.I.; Bloemen, H.J.Th.; De Loos, S.; Marra, M.; Rombout, P.J.A.; Steentjes, G.M.; Van Veen, M.P.

    1997-12-01

    Analysis of inhalatory exposure to air pollution is an important area of investigation when assessing the risks of air pollution for human health. Inhalatory exposure research focuses on the exposure of humans to air pollutants and the entry of these pollutants into the human respiratory tract. The principal grounds for studying the inhalatory exposure of humans to air pollutants are formed by the need for realistic exposure/dose estimates to evaluate the health effects of these pollutants. The AirPEx (Air Pollution Exposure) model, developed to assess the time- and space-dependence of inhalatory exposure of humans to air pollution, has been implemented for use as a Windows 3.1 computer program. The program is suited to estimating various exposure and dose quantities for individuals, as well as for populations and subpopulations. This report describes the fundamentals of the AirPEx model and provides a user manual for the computer program. Several examples included in the report illustrate the possibilities of the AirPEx model in exposure assessment. The model will be used at the National Institute of Public Health and the Environment as a tool in analysing the current exposure of the Dutch population to air pollutants. 57 refs.

  18. Developing a General Population Job-Exposure Matrix in the Absence of Sufficient Exposure Monitoring Data

    OpenAIRE

    Tmannetje, AM; McLean, DJ; Eng, AJ; Kromhout, H; Kauppinen, T; Fevotte, J; Pearce, NE

    2011-01-01

    In New Zealand, there is a need for a comprehensive and accessible database with national occupational exposure information, such as a general population job-exposure matrix (GPJEM). However, few New Zealand-specific exposure data exist that could be used to construct such a GPJEM. Here, we present the methods used to develop a GPJEM for New Zealand (NZJEM), by combining GPJEMs from other countries with New Zealand-specific exposure information, using wood dust as an example to illustrate thi...

  19. The Effect of Uncertainty in Exposure Estimation on the Exposure-Response Relation between 1,3-Butadiene and Leukemia

    Directory of Open Access Journals (Sweden)

    George Maldonado

    2009-09-01

    Full Text Available Abstract: In a follow-up study of mortality among North American synthetic rubber industry workers, cumulative exposure to 1,3-butadiene was positively associated with leukemia. Problems with historical exposure estimation, however, may have distorted the association. To evaluate the impact of potential inaccuracies in exposure estimation, we conducted uncertainty analyses of the relation between cumulative exposure to butadiene and leukemia. We created the 1,000 sets of butadiene estimates using job-exposure matrices consisting of exposure values that corresponded to randomly selected percentiles of the approximate probability distribution of plant-, work area/job group-, and year specific butadiene ppm. We then analyzed the relation between cumulative exposure to butadiene and leukemia for each of the 1,000 sets of butadiene estimates. In the uncertainty analysis, the point estimate of the RR for the first non zero exposure category (>0–<37.5 ppm-years was most likely to be about 1.5. The rate ratio for the second exposure category (37.5–<184.7 ppm-years was most likely to range from 1.5 to 1.8. The RR for category 3 of exposure (184.7–<425.0 ppm-years was most likely between 2.1 and 3.0. The RR for the highest exposure category (425.0+ ppm-years was likely to be between 2.9 and 3.7. This range off RR point estimates can best be interpreted as a probability distribution that describes our uncertainty in RR point estimates due to uncertainty in exposure estimation. After considering the complete probability distributions of butadiene exposure estimates, the exposure-response association of butadiene and leukemia was maintained. This exercise was a unique example of how uncertainty analyses can be used to investigate and support an observed measure of effect when occupational exposure estimates are employed in the absence of direct exposure measurements.

  20. Center for the Polyurethanes Industry summary of unpublished industrial hygiene studies related to the evaluation of emissions of spray polyurethane foam insulation.

    Science.gov (United States)

    Wood, Richard D

    2017-09-01

    Spray polyurethane foam (SPF) insulation is used as thermal insulation for residential and commercial buildings. It has many advantages over other forms insulation; however, concerns have been raised related to chemical emissions during and after application. The American Chemistry Council's (ACC's) Center for the Polyurethanes Industry (CPI) has gathered previously unpublished industrial hygiene air sampling studies submitted by member companies that were completed during an eight-year period from 2007-2014. These studies address emissions from medium density closed cell and low density open cell formulations. This article summarizes the results of personal and area air samples collected during application and post application of SPF to interior building surfaces in both laboratory and field environments. Chemicals of interest included: Volatile Organic Compounds (VOCs), methylene diphenyl diisocyanate (MDI), flame retardants, amine catalysts, blowing agents, and aldehydes. Overall, the results indicate that SPF applicators and workers in close proximity to the application are potentially exposed to MDI in excess of recommended and governmental occupational exposure limits and should use personal protective equipment (PPE) consisting of air supplied respirators and full-body protective clothing to reduce exposure. Catalyst emissions can be reduced by using reactive catalysts in SPF formulations, and mechanical ventilation is important in controlling emissions during and after application.

  1. Hazards of radiation exposure

    International Nuclear Information System (INIS)

    Solomon, S.B.

    1982-01-01

    Radiation induced carcinogenesis and mutagenesis form the main risks to health from exposure to low levels of radiation. There is scant data on somatic and genetic risks at environmental and occupational levels of radiation exposure. The available data on radiation induced carcinogenesis and mutagenesis are for high doses and high dose rates of radiation. Risk assessments for low level radiation are obtained using these data, assuming a linear dose-response relationship. During uranium mining the chief source of radiation hazard is inhalation of radon daughters. The correlation between radon daughter exposure and the increased incidence of lung cancer has been well documented. For radiation exposures at and below occupational limits, the associated risk of radiation induced cancers and genetic abnormalities is small and should not lead to a detectable increase over naturally occurring rates

  2. Safety lock for radiography exposure device

    International Nuclear Information System (INIS)

    Gaines, T.M.

    1982-01-01

    A safety lock for securing a radiation source in a radiography exposure device is disclosed. The safety lock prevents the inadvertent extension of the radiation source from the exposure device. The exposure devices are used extensively in industry for nondestructive testing of metal materials for defect. Unnecessary exposure of the radiographer or operator occurs not infrequently due to operator's error in believing that the radiation source is secured in the exposure device when, in fact, it is not. The present invention solves this problem of unnecessary exposure by releasingly trapping the radiation source in the shield of the radiography exposure device each time the source is retracted therein so that it is not inadvertently extended therefrom without the operator resetting the safety lock, thereby releasing the radiation source. Further, the safety lock includes an indicator which indicates when the source is trapped in the exposure device and also when it is untrapped. The safety lock is so designed that it does not prevent the return of the source to the trapped, shielded position in the exposure device. Further the safety lock includes a key means for locking the radiation source in the trapped position. The key means cannot be actuated until said radiation source is in said trapped position to further insure the safety lock cannot be inadvertently locked with the source untrapped and thus still extendable from the exposure device

  3. Exposure scenario libraries as a tool for exposure assessment

    International Nuclear Information System (INIS)

    Jiménez, Araceli Sánchez; Rashid, Shahzad; Van Tongeren, Martie; Brouwer, Derk; Fransman, Wouter; Fito, Carlos; Boulougouris, George

    2015-01-01

    The development of nanotechnology has reached a point where it is being widely applied, and numerous nanomaterials and nano-enabled products are handled across a broad range of industrial sectors. Exposure extends beyond occupational settings as products containing nanomaterials are used by different consumer groups.Despite the knowledge on their toxic effects is growing there is still not OEL for most NMS and therefore the precautionary approach is still used where levels are kept as low as possible Therefore there is a need to assess workers and consumers exposure. (paper)

  4. Stimulus Threat and Exposure Context Modulate the Effect of Mere Exposure on Approach Behaviors.

    Science.gov (United States)

    Young, Steven G; Jones, Isaiah F; Claypool, Heather M

    2016-01-01

    Mere-exposure (ME) research has found that initially neutral objects made familiar are preferred relative to novel objects. Recent work extends these preference judgments into the behavioral domain by illustrating that mere exposure prompts approach-oriented behavior toward familiar stimuli. However, no investigations have examined the effect of mere exposure on approach-oriented behavior toward threatening stimuli. The current work examines this issue and also explores how exposure context interacts with stimulus threat to influence behavioral tendencies. In two experiments participants were presented with both mere-exposed and novel stimuli and approach speed was assessed. In the first experiment, when stimulus threat was presented in a homogeneous format (i.e., participants viewed exclusively neutral or threatening stimuli), ME potentiated approach behaviors for both neutral and threatening stimuli. However, in the second experiment, in which stimulus threat was presented in a heterogeneous fashion (i.e., participants viewed both neutral and threatening stimuli), mere exposure facilitated approach only for initially neutral stimuli. These results suggest that ME effects on approach behaviors are highly context sensitive and depend on both stimulus valence and exposure context. Further implications of these findings for the ME literature are discussed.

  5. Radiation-induced taste aversion: effects of radiation exposure level and the exposure-taste interval

    International Nuclear Information System (INIS)

    Spector, A.C.; Smith, J.C.; Hollander, G.R.

    1986-01-01

    Radiation-induced taste aversion has been suggested to possibly play a role in the dietary difficulties observed in some radiotherapy patients. In rats, these aversions can still be formed even when the radiation exposure precedes the taste experience by several hours. This study was conducted to examine whether increasing the radiation exposure level could extend the range of the exposure-taste interval that would still support the formation of a taste aversion. Separate groups of rats received either a 100 or 300 R gamma-ray exposure followed 1, 3, 6, or 24 h later by a 10-min saccharin (0.1% w/v) presentation. A control group received a sham exposure followed 1 h later by a 10-min saccharin presentation. Twenty-four hours following the saccharin presentation all rats received a series of twelve 23-h two-bottle preference tests between saccharin and water. The results indicated that the duration of the exposure-taste interval plays an increasingly more important role in determining the initial extent of the aversion as the dose decreases. The course of recovery from taste aversion seems more affected by dose than by the temporal parameters of the conditioning trial

  6. Assessment of exposure to shiftwork mechanisms in the general population: the development of a new job-exposure matrix.

    Science.gov (United States)

    Fernandez, Renae C; Peters, Susan; Carey, Renee N; Davies, Michael J; Fritschi, Lin

    2014-10-01

    To develop a job-exposure matrix (JEM) that estimates exposure to eight variables representing different aspects of shiftwork among female workers. Occupational history and shiftwork exposure data were obtained from a population-based breast cancer case-control study. Exposure to light at night, phase shift, sleep disturbances, poor diet, lack of physical activity, lack of vitamin D, and graveyard and early morning shifts, was calculated by occupational code. Three threshold values based on the frequency of exposure were considered (10%, 30% and 50%) for use as cut-offs in determining exposure for each occupational code. JEM-based exposure classification was compared with that from the OccIDEAS application (job-specific questionnaires and assessment by rules) by assessing the effect on the OR for phase shift and breast cancer. Using data from the Australian Workplace Exposure Study, the specificity and sensitivity of the threshold values were calculated for each exposure variable. 127 of 413 occupational codes involved exposure to one or more shiftwork variables. Occupations with the highest probability of exposure shiftwork included nurses and midwives. Using the 30% threshold, the OR for the association between phase shift exposure and breast cancer was decreased and no longer statistically significant (OR=1.14, 95% CI 0.92 to 1.42). The 30% cut-off point demonstrated best specificity and sensitivity, although results varied between exposure variables. This JEM provides a set of indicators reflecting biologically plausible mechanisms for the potential impact of shiftwork on health and may provide an alternative method of exposure assessment in the absence of detailed job history and exposure data. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  7. Aircrew radiation exposure: sources-risks-measurement

    International Nuclear Information System (INIS)

    Duftschmid, K.E.

    1994-05-01

    A short review is given on the actual aircrew exposure and its sources. The resulting risks for harmful effects to the health and discuss methods for in-flight measurements of exposure is evaluated. An idea for a fairly simple and economic approach to a practical, airborne active dosimeter for the assessment of individual crew exposure is presented. The exposure of civil aircrew to cosmic radiation, should not be considered a tremendous risk to the health, there is no reason for panic. However, being significantly higher than the average exposure to radiation workers, it can certainly not be neglected. As recommended by ICRP, aircrew exposure has to be considered occupational radiation exposure and aircrews are certainly entitled to the same degree of protection, as other ground-based radiation workers have obtained by law, since long time. (author)

  8. Effects after prenatal radiation exposures

    International Nuclear Information System (INIS)

    Streffer, C.

    2001-01-01

    The mammalian organism is highly radiosensitive during all prenatal developmental periods. For most effects a dose relationship with a threshold is observed. These threshold doses are generally above the exposures from medical diagnostic procedures. The quality and extent of radiation effects are very much dependent on the developmental stage during which an exposure takes place and on the radiation dose. An exposure during the preimplantation period will cause lethality. Malformations are usually induced after exposures during the major organogenesis. Growth retardation is also possible during the late organogenesis and foetal periods. The lower limits of threshold doses for these effects are in the range of 100 mGy. A radiation exposure during the early foetal period can lead to severe mental retardation and impairment of intelligence. There are very serious effects with radiation doses above 0.3 Gy. Carcinogenesis can apparently occur after radiation exposures during the total prenatal development period. The radiation risk factor up to now has not been clear, but it seems that it is in the range of risk factors for cancer that are observed after exposures during childhood. For radiation doses that are used in radiological diagnostics the risk is zero or very low. A termination of pregnancy after doses below 100 mGy should not be considered. (author)

  9. Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential.

    Science.gov (United States)

    Mitchell, Jade; Arnot, Jon A; Jolliet, Olivier; Georgopoulos, Panos G; Isukapalli, Sastry; Dasgupta, Surajit; Pandian, Muhilan; Wambaugh, John; Egeghy, Peter; Cohen Hubal, Elaine A; Vallero, Daniel A

    2013-08-01

    While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA's need to develop novel approaches and tools for rapidly prioritizing chemicals, a "Challenge" was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA's effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Comparison of modeling approaches to prioritize chemicals based on estimates of exposure and exposure potential

    Science.gov (United States)

    Mitchell, Jade; Arnot, Jon A.; Jolliet, Olivier; Georgopoulos, Panos G.; Isukapalli, Sastry; Dasgupta, Surajit; Pandian, Muhilan; Wambaugh, John; Egeghy, Peter; Cohen Hubal, Elaine A.; Vallero, Daniel A.

    2014-01-01

    While only limited data are available to characterize the potential toxicity of over 8 million commercially available chemical substances, there is even less information available on the exposure and use-scenarios that are required to link potential toxicity to human and ecological health outcomes. Recent improvements and advances such as high throughput data gathering, high performance computational capabilities, and predictive chemical inherency methodology make this an opportune time to develop an exposure-based prioritization approach that can systematically utilize and link the asymmetrical bodies of knowledge for hazard and exposure. In response to the US EPA’s need to develop novel approaches and tools for rapidly prioritizing chemicals, a “Challenge” was issued to several exposure model developers to aid the understanding of current systems in a broader sense and to assist the US EPA’s effort to develop an approach comparable to other international efforts. A common set of chemicals were prioritized under each current approach. The results are presented herein along with a comparative analysis of the rankings of the chemicals based on metrics of exposure potential or actual exposure estimates. The analysis illustrates the similarities and differences across the domains of information incorporated in each modeling approach. The overall findings indicate a need to reconcile exposures from diffuse, indirect sources (far-field) with exposures from directly, applied chemicals in consumer products or resulting from the presence of a chemical in a microenvironment like a home or vehicle. Additionally, the exposure scenario, including the mode of entry into the environment (i.e. through air, water or sediment) appears to be an important determinant of the level of agreement between modeling approaches. PMID:23707726

  11. Head and neck cancer due to heavy metal exposure via tobacco smoking and professional exposure: A review

    International Nuclear Information System (INIS)

    Khlifi, Rim; Hamza-Chaffai, Amel

    2010-01-01

    Chronic exposures to heavy metals via tobacco smoking and professional exposure may increase the risk of head and neck cancer, although the epidemiologic evidence is limited by problems of low study power and inadequate adjustment for tobacco and professional exposure use. Numerous scientific reviews have examined the association of various heavy metals exposure with respiratory cancer as well as other cancer types, but few have been published on head and neck cancer. The purpose of this paper, therefore, is to review the head and neck tract cancer-related data on exposure to heavy metals via smoking and working exposure and to study the major mechanisms underlying some toxic metals carcinogenesis.

  12. Pesticide Exposure in Children

    Science.gov (United States)

    Roberts, James R.; Karr, Catherine J.

    2018-01-01

    Pesticides are a collective term for a wide array of chemicals intended to kill unwanted insects, plants, molds, and rodents. Food, water, and treatment in the home, yard, and school are all potential sources of children’s exposure. Exposures to pesticides may be overt or subacute, and effects range from acute to chronic toxicity. In 2008, pesticides were the ninth most common substance reported to poison control centers, and approximately 45% of all reports of pesticide poisoning were for children. Organophosphate and carbamate poisoning are perhaps the most widely known acute poisoning syndromes, can be diagnosed by depressed red blood cell cholinesterase levels, and have available antidotal therapy. However, numerous other pesticides that may cause acute toxicity, such as pyrethroid and neonicotinoid insecticides, herbicides, fungicides, and rodenticides, also have specific toxic effects; recognition of these effects may help identify acute exposures. Evidence is increasingly emerging about chronic health implications from both acute and chronic exposure. A growing body of epidemiological evidence demonstrates associations between parental use of pesticides, particularly insecticides, with acute lymphocytic leukemia and brain tumors. Prenatal, household, and occupational exposures (maternal and paternal) appear to be the largest risks. Prospective cohort studies link early-life exposure to organophosphates and organochlorine pesticides (primarily DDT) with adverse effects on neurodevelopment and behavior. Among the findings associated with increased pesticide levels are poorer mental development by using the Bayley index and increased scores on measures assessing pervasive developmental disorder, inattention, and attention-deficit/hyperactivity disorder. Related animal toxicology studies provide supportive biological plausibility for these findings. Additional data suggest that there may also be an association between parental pesticide use and adverse birth

  13. Exposure scenarios for workers

    NARCIS (Netherlands)

    Marquart, H.; Northage, C.; Money, C.

    2007-01-01

    The new European chemicals legislation REACH (Registration, Evaluation, Authorisation and restriction of Chemicals) requires the development of Exposure Scenarios describing the conditions and risk management measures needed for the safe use of chemicals. Such Exposure Scenarios should integrate

  14. 40 CFR 721.6498 - Modified polyisocyanates (generic).

    Science.gov (United States)

    2010-07-01

    ... paragraph (a)(2) of this section. (2) The significant new uses are: (i) Protection in the workplace... diisocyanate concentrations; an appropriate National Institute for Occupational Safety and Health/Mine Safety... SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical...

  15. 78 FR 44857 - Seventy-Second Report of the TSCA Interagency Testing Committee to the Administrator of the...

    Science.gov (United States)

    2013-07-24

    ..., 98 High Production Volume (HPV) Challenge Program orphan chemicals, and 50 diisocyanates and related... HPV Challenge Program orphan chemicals because they no longer meet the = 1 million lb criterion for... process TSCA-covered chemicals and you may be identified by the North American Industrial Classification...

  16. 76 FR 21339 - Certain New Chemicals; Receipt and Status Information

    Science.gov (United States)

    2011-04-15

    ... identification, pass through a metal detector, and sign the EPA visitor log. All visitor bags are processed... for (G) Alkyl producing siloxane polymer silicon oxycarbide ceramics. P-11-0071......... 11/05/10 02... polypropylene light/electron glycol ether beam curable polymer with formulations. isophorone diisocyanate...

  17. Neutron exposure

    International Nuclear Information System (INIS)

    Prillinger, G.; Konynenburg, R.A. van

    1998-01-01

    As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. In chapter 6, LWR-PV neutron transport calculations and dosimetry methods and how they are combined to evaluate the neutron exposure of the steel of pressure vessels are discussed. An effort to correlate neutron exposure parameters with damage is made

  18. Challenges and perspectives of nanoparticle exposure assessment.

    Science.gov (United States)

    Lee, Ji Hyun; Moon, Min Chaul; Lee, Joon Yeob; Yu, Il Je

    2010-06-01

    Nanoparticle exposure assessment presents a unique challenge in the field of occupational and environmental health. With the commercialization of nanotechnology, exposure usually starts from the workplace and then spreads to environment and consumer exposure. This report discusses the current trends of nanoparticle exposure assessment, including the definition of nanotechnology relevant terms, essential physicochemical properties for nanomaterial characterization, current international activities related nanomaterial safety, and exposure assessment standard development for nanotechnology. Further this report describes challenges of nanoparticle exposure assessment such as background measurement, metrics of nanoparticle exposure assessment and personal sampling.

  19. Radiation exposure during ESWL

    International Nuclear Information System (INIS)

    McCullough, D.L.; Van Swearingen, F.L.; Dyer, R.B.; Appel, B.

    1987-01-01

    This paper discusses exposure to ionizing radiation by the ESWL patient and for health professionals. Although the patient is exposed acutely to the highest level of radiation, the lithotripter team is chronically exposed to ionizing radiation at varying levels. Attention to detail is important in reducing that exposure. The operator should follow the guidelines set forth in this chapter in order to minimize exposure to the patient, himself or herself, and to all co-workers. At the present time, investigation of an alternative modality for stone localization, ultrasound, is being investigated

  20. Ethical issues in medico-legal exposures

    International Nuclear Information System (INIS)

    O'Reilly, G.; Malone, J. F.

    2008-01-01

    The Medical Exposure Directive (MED) 97/43/Euratom defines medico-legal procedures as 'procedures performed for insurance or legal purposes without a medical indication'. The term 'medico-legal exposures' covers a wide range of possible types of exposures, very different in nature, for which the only feature in common is the fact that the main reason for performing them does not relate directly to the health of the individual being exposed to ionising radiation. The key issue in medico-legal exposures is justification. Balancing the advantages and disadvantages of such exposures is complex because not only can these be difficult to quantify and hence compare, but often the advantage may be to society whereas the disadvantage is usually to an individual. This adds an additional layer of ethical complexity to the problem and one, which requires input from a number of sources beyond the established radiation protection community. Because medico-legal exposures are considered to be medical exposures, they are not subject to dose limits. In medico-legal exposures where the benefit is not necessarily to the individual undergoing the exposure, the question must be asked as to whether or not this is an appropriate framework within which to conduct such exposures. This paper looks at the current situation in Europe, highlighting some of the particular problems that have arisen, and tries to identify the areas, which require further clarification and guidance. (authors)

  1. Early cannabinoid exposure influences neuroendocrine and reproductive functions in male mice: I. Prenatal exposure.

    Science.gov (United States)

    Dalterio, S; Steger, R; Mayfield, D; Bartke, A

    1984-01-01

    Maternal exposure to delta 9-tetrahydrocannabinol (THC), the major psychoactive constituent in marihuana, or to the non-psychoactive cannabinol (CBN) or cannabidiol (CBD) alters endocrine functions and concentrations of brain biogenic amines in their male offspring. Prenatal CBN exposure on day 18 of gestation resulted in decreased plasma FSH levels, testicular testosterone (T) concentrations, and seminal vesicles weights, but increased plasma levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) post-castration in adulthood. Prenatal exposure to THC significantly enhanced the responsiveness of the testes to intratesticular LH injection in vivo and tended to increase human chorionic gonadotropin (hCG)-stimulated T production by decapsulated testes in vitro. In the CBN-exposed mice, hCG-stimulated T production was enhanced, while CBD exposure had no effect. Prenatal THC exposure altered the negative feedback effects of exogenous gonadal steroids in castrated adults, with lower plasma T and FSH levels after 20 micrograms T than in castrated controls. In contrast, CBD-exposed mice had higher levels of LH in plasma post-castration. In CBN-exposed adults, two weeks post-castration the concentration of norepinephrine (NE) and dopamine (DA) in hypothalamus and remaining brain were reduced, while levels of serotonin (5-HT) and its metabolite, 5-HIAA, were elevated compared to that in castrated OIL-controls. Prenatal CBD-exposure also reduced NE and elevated 5-HT and 5-HIAA, but did not affect DA levels post-castration. Concentrations of brain biogenic amines were not influenced by prenatal THC exposure in the present study. A single prenatal exposure to psychoactive or non-psychoactive components of marihuana results in long term alterations in the function of the hypothalamo-pituitary-gonadal axis. Changes in the concentrations of brain biogenic amines may be related to these effects of prenatal cannabinoids on endocrine function in adult male mice.

  2. Mercury exposure in children: a review

    International Nuclear Information System (INIS)

    Counter, S. Allen; Buchanan, Leo H.

    2004-01-01

    Exposure to toxic mercury (Hg) is a growing health hazard throughout the world today. Recent studies show that mercury exposure may occur in the environment, and increasingly in occupational and domestic settings. Children are particularly vulnerable to Hg intoxication, which may lead to impairment of the developing central nervous system, as well as pulmonary and nephrotic damage. Several sources of toxic Hg exposure in children have been reported in biomedical literature: (1) methylmercury, the most widespread source of Hg exposure, is most commonly the result of consumption of contaminated foods, primarily fish; (2) ethylmercury, which has been the subject of recent scientific inquiry in relation to the controversial pediatric vaccine preservative thimerosal; (3) elemental Hg vapor exposure through accidents and occupational and ritualistic practices; (4) inorganic Hg through the use of topical Hg-based skin creams and in infant teething powders; (5) metallic Hg in dental amalgams, which release Hg vapors, and Hg 2+ in tissues. This review examines recent epidemiological studies of methylmercury exposure in children. Reports of elemental Hg vapor exposure in children through accidents and occupational practices, and the more recent observations of the increasing use of elemental Hg for magico-religious purposes in urban communities are also discussed. Studies of inorganic Hg exposure from the widespread use of topical beauty creams and teething powders, and fetal/neonatal Hg exposure from maternal dental amalgam fillings are reviewed. Considerable attention was given in this review to pediatric methylmercury exposure and neurodevelopment because it is the most thoroughly investigated Hg species. Each source of Hg exposure is reviewed in relation to specific pediatric health effects, particularly subtle neurodevelopmental disorders

  3. Self-Assembled Cationic Biodegradable Nanoparticles from pH-Responsive Amino-Acid-Based Poly(Ester Urea Urethane)s and Their Application As a Drug Delivery Vehicle.

    Science.gov (United States)

    He, Mingyu; Potuck, Alicia; Kohn, Julie C; Fung, Katharina; Reinhart-King, Cynthia A; Chu, Chih-Chang

    2016-02-08

    The objective of this study is to develop a new family of biodegradable and biologically active copolymers and their subsequent self-assembled cationic nanoparticles as better delivery vehicles for anticancer drugs to achieve the synergism between the cytotoxicity effects of the loaded drugs and the macrophage inflammatory response of the delivery vehicle. This family of cationic nanoparticles was formulated from a new family of amphiphilic cationic Arginine-Leucine (Arg-Leu)-based poly(ester urea urethane) (Arg-Leu PEUU) synthesized from four building blocks (amino acids, diols, glycerol α-monoallyl ether, and 1,6 hexamethylene diisocyanate). The chemical, physical, and biological properties of Arg-Leu PEUU biomaterials can be tuned by controlling the feed ratio of the four building blocks. The Arg-Leu PEUU copolymers have weight-average molecular weights from 13.4 to 16.8 kDa and glass-transition temperatures from -3.4 to -4.6 °C. The self-assembled cationic nanoparticles (Arg-Leu PEUU NPs) were prepared using a facile dialysis method. Arg-Leu PEUU NPs have average diameters ranging from 187 to 272 nm, show good biocompatibility with 3T3 fibroblasts, and they support bovine aortic endothelial cell (BAEC) proliferation and adhesion. Arg-Leu PEUU NPs also enhanced the macrophages' production of tumor necrosis factor-α (TNF-α) and nitric oxide (NO), but produced relatively low levels of interleukin-10 (IL-10), and therefore, the antitumor activity of macrophages might be enhanced. Arg-Leu PEUU NPs were taken up by HeLa cells after 4 h of incubation. The in vitro hemolysis assay showed the cationic Arg-Leu PEUU NPs increased their chance of endosomal escape at a more acidic pH. Doxorubicin (DOX) was successfully incorporated into the Arg-Leu PEUU NPs, and the DOX-loaded Arg-Leu PEUU NPs exhibited a pH-dependent drug release profile with accelerated release kinetics in a mild acidic condition. The DOX-loaded 6-Arg-4-Leu-4 A/L-2/1 NPs showed higher HeLa cell

  4. Nerve regeneration using tubular scaffolds from biodegradable polyurethane.

    Science.gov (United States)

    Hausner, T; Schmidhammer, R; Zandieh, S; Hopf, R; Schultz, A; Gogolewski, S; Hertz, H; Redl, H

    2007-01-01

    In severe nerve lesion, nerve defects and in brachial plexus reconstruction, autologous nerve grafting is the golden standard. Although, nerve grafting technique is the best available approach a major disadvantages exists: there is a limited source of autologous nerve grafts. This study presents data on the use of tubular scaffolds with uniaxial pore orientation from experimental biodegradable polyurethanes coated with fibrin sealant to regenerate a 8 mm resected segment of rat sciatic nerve. Tubular scaffolds: prepared by extrusion of the polymer solution in DMF into water coagulation bath. The polymer used for the preparation of tubular scaffolds was a biodegradable polyurethane based on hexamethylene diisocyanate, poly(epsilon-caprolactone) and dianhydro-D-sorbitol. EXPERIMENTAL MODEL: Eighteen Sprague Dawley rats underwent mid-thigh sciatic nerve transection and were randomly assigned to two experimental groups with immediate repair: (1) tubular scaffold, (2) 180 degrees rotated sciatic nerve segment (control). Serial functional measurements (toe spread test, placing tests) were performed weekly from 3rd to 12th week after nerve repair. On week 12, electrophysiological assessment was performed. Sciatic nerve and scaffold/nerve grafts were harvested for histomorphometric analysis. Collagenic connective tissue, Schwann cells and axons were evaluated in the proximal nerve stump, the scaffold/nerve graft and the distal nerve stump. The implants have uniaxially-oriented pore structure with a pore size in the range of 2 micorm (the pore wall) and 75 x 700 microm (elongated pores in the implant lumen). The skin of the tubular implants was nonporous. Animals which underwent repair with tubular scaffolds of biodegradable polyurethanes coated with diluted fibrin sealant had no significant functional differences compared with the nerve graft group. Control group resulted in a trend-wise better electrophysiological recovery but did not show statistically significant

  5. Quality assurance: using the exposure index and the deviation index to monitor radiation exposure for portable chest radiographs in neonates

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Mervyn D. [Indiana University School of Medicine, Department of Radiology, Riley Children' s Hospital, Indianapolis, IN (United States); Riley Hospital for Children, Department of Radiology, Indianapolis, IN (United States); Cooper, Matt L.; Piersall, Kelly [Indiana University School of Medicine, Department of Radiology, Riley Children' s Hospital, Indianapolis, IN (United States); Apgar, Bruce K. [Agfa HealthCare Corporation, Greenville, SC (United States)

    2011-05-15

    Many methods are used to track patient exposure during acquisition of plain film radiographs. A uniform international standard would aid this process. To evaluate and describe a new, simple quality-assurance method for monitoring patient exposure. This method uses the ''exposure index'' and the ''deviation index,'' recently developed by the International Electrotechnical Commission (IEC) and American Association of Physicists in Medicine (AAPM). The deviation index measures variation from an ideal target exposure index value. Our objective was to determine whether the exposure index and the deviation index can be used to monitor and control exposure drift over time. Our Agfa workstation automatically keeps a record of the exposure index for every patient. The exposure index and deviation index were calculated on 1,884 consecutive neonatal chest images. Exposure of a neonatal chest phantom was performed as a control. Acquisition of the exposure index and calculation of the deviation index was easily achieved. The weekly mean exposure index of the phantom and the patients was stable and showed <10% change during the study, indicating no exposure drift during the study period. The exposure index is an excellent tool to monitor the consistency of patient exposures. It does not indicate the exposure value used, but is an index to track compliance with a pre-determined target exposure. (orig.)

  6. Quality assurance: using the exposure index and the deviation index to monitor radiation exposure for portable chest radiographs in neonates

    International Nuclear Information System (INIS)

    Cohen, Mervyn D.; Cooper, Matt L.; Piersall, Kelly; Apgar, Bruce K.

    2011-01-01

    Many methods are used to track patient exposure during acquisition of plain film radiographs. A uniform international standard would aid this process. To evaluate and describe a new, simple quality-assurance method for monitoring patient exposure. This method uses the ''exposure index'' and the ''deviation index,'' recently developed by the International Electrotechnical Commission (IEC) and American Association of Physicists in Medicine (AAPM). The deviation index measures variation from an ideal target exposure index value. Our objective was to determine whether the exposure index and the deviation index can be used to monitor and control exposure drift over time. Our Agfa workstation automatically keeps a record of the exposure index for every patient. The exposure index and deviation index were calculated on 1,884 consecutive neonatal chest images. Exposure of a neonatal chest phantom was performed as a control. Acquisition of the exposure index and calculation of the deviation index was easily achieved. The weekly mean exposure index of the phantom and the patients was stable and showed <10% change during the study, indicating no exposure drift during the study period. The exposure index is an excellent tool to monitor the consistency of patient exposures. It does not indicate the exposure value used, but is an index to track compliance with a pre-determined target exposure. (orig.)

  7. Radiation exposure and infant cancer

    Energy Technology Data Exchange (ETDEWEB)

    Watari, T [Tokyo Univ. (Japan). Faculty of Medicine

    1974-12-01

    Medical exposures accompanied by an increase in radiation use in the field of pediatrics were described. Basic ideas and countermeasures to radiation injuries were outlined. In order to decrease the medical exposure, it is necessary for the doctor, x-ray technician and manufacturer to work together. The mechanism and characteristics of radio carcinogenesis were also mentioned. Particularly, the following two points were described: 1) How many years does it take before carcinogenesis appears as a result of radiation exposure in infancy 2) How and when does the effect of fetus exposure appear. Radiosensitivity in infants and fetuses is greater than that of an adult. The occurrence of leukemia caused by prenatal exposure was reviewed. The relation between irradiation for therapy and morbidity of thyroid cancer was mentioned. Finally, precautions necessary for infants, pregnant women and nursing mothers when using radioisotopes were mentioned.

  8. Cea-Expo: A facility exposure matrix to assess passed exposure to chemical carcinogens and radionuclides of nuclear workers

    International Nuclear Information System (INIS)

    Telle-Lamberton, M.; Bouville, P.; Bergot, D.; Gagneau, M.; Marot, S.; Telle-Lamberton, M.; Giraud, J.M.; Gelas, J.M.

    2005-01-01

    A 'Facility-Exposure Matrix' (FEM) is proposed to assess exposure to chemical carcinogens and radionuclides in a cohort of nuclear workers. Exposures are to be attributed in the following way: a worker reports to an administrative unit and/or is monitored for exposure to ionising radiation in a specific workplace. These units are connected with a list of facilities for which exposure is assessed through a group of experts. The entire process of the FEM applied in one of the nuclear centres included in the study shows that the FEM is feasible: exposure durations as well as groups of correlated exposures are presented but have to be considered as possible rather than positive exposures. Considering the number of facilities to assess (330), ways to simplify the method are proposed: (i) the list of exposures will be restricted to 18 chemical products retained from an extensive bibliography study; (ii) for each of the following classes of facilities: nuclear reactors, fuel fabrication, high-activity laboratories and radiation chemistry, accelerators and irradiators, waste treatment, biology, reprocessing, fusion, occupational exposure will be deduced from the information already gathered by the initial method. Besides taking into account confusion factors in the low doses epidemiological study of nuclear workers, the matrix should help in the assessment of internal contamination and chemical exposures in the nuclear industry. (author)

  9. Development of a spatial stochastic multimedia exposure model to assess population exposure at a regional scale

    Energy Technology Data Exchange (ETDEWEB)

    Caudeville, Julien, E-mail: Julien.CAUDEVILLE@ineris.fr [INERIS (French National Institute for Industrial Environment and Risks), Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France); Joint research unit UMR 6599, Heudiasyc (Heuristic and Diagnoses of Complex Systems), University of Technology of Compiegne and CNRS, Rue du Dr Schweitzer, 60200 Compiegne (France); Bonnard, Roseline, E-mail: Roseline.BONNARD@ineris.fr [INERIS (French National Institute for Industrial Environment and Risks), Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France); Boudet, Celine, E-mail: Celine.BOUDET@ineris.fr [INERIS (French National Institute for Industrial Environment and Risks), Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France); Denys, Sebastien, E-mail: Sebastien.DENYS@ineris.fr [INERIS (French National Institute for Industrial Environment and Risks), Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France); Govaert, Gerard, E-mail: gerard.govaert@utc.fr [Joint research unit UMR 6599, Heudiasyc (Heuristic and Diagnoses of Complex Systems), University of Technology of Compiegne and CNRS, Rue du Dr Schweitzer, 60200 Compiegne (France); Cicolella, Andre, E-mail: Andre.CICOLELLA@ineris.fr [INERIS (French National Institute for Industrial Environment and Risks), Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France)

    2012-08-15

    Analyzing the relationship between the environment and health has become a major focus of public health efforts in France, as evidenced by the national action plans for health and the environment. These plans have identified the following two priorities: -identify and manage geographic areas where hotspot exposures are a potential risk to human health; and -reduce exposure inequalities. The aim of this study is to develop a spatial stochastic multimedia exposure model for detecting vulnerable populations and analyzing exposure determinants at a fine resolution and regional scale. A multimedia exposure model was developed by INERIS to assess the transfer of substances from the environment to humans through inhalation and ingestion pathways. The RESPIR project adds a spatial dimension by linking GIS (Geographic Information System) to the model. Tools are developed using modeling, spatial analysis and geostatistic methods to build and discretize interesting variables and indicators from different supports and resolutions on a 1-km{sup 2} regular grid. We applied this model to the risk assessment of exposure to metals (cadmium, lead and nickel) using data from a region in France (Nord-Pas-de-Calais). The considered exposure pathways include the atmospheric contaminant inhalation and ingestion of soil, vegetation, meat, egg, milk, fish and drinking water. Exposure scenarios are defined for different reference groups (age, dietary properties, and the fraction of food produced locally). The two largest risks correspond to an ancient industrial site (Metaleurop) and the Lille agglomeration. In these areas, cadmium, vegetation ingestion and soil contamination are the principal determinants of the computed risk. -- Highlights: Black-Right-Pointing-Pointer We present a multimedia exposure model for mapping environmental disparities. Black-Right-Pointing-Pointer We perform a risk assessment on a region of France at a fine scale for three metals. Black-Right-Pointing-Pointer We

  10. Development of a spatial stochastic multimedia exposure model to assess population exposure at a regional scale

    International Nuclear Information System (INIS)

    Caudeville, Julien; Bonnard, Roseline; Boudet, Céline; Denys, Sébastien; Govaert, Gérard; Cicolella, André

    2012-01-01

    Analyzing the relationship between the environment and health has become a major focus of public health efforts in France, as evidenced by the national action plans for health and the environment. These plans have identified the following two priorities: -identify and manage geographic areas where hotspot exposures are a potential risk to human health; and -reduce exposure inequalities. The aim of this study is to develop a spatial stochastic multimedia exposure model for detecting vulnerable populations and analyzing exposure determinants at a fine resolution and regional scale. A multimedia exposure model was developed by INERIS to assess the transfer of substances from the environment to humans through inhalation and ingestion pathways. The RESPIR project adds a spatial dimension by linking GIS (Geographic Information System) to the model. Tools are developed using modeling, spatial analysis and geostatistic methods to build and discretize interesting variables and indicators from different supports and resolutions on a 1-km 2 regular grid. We applied this model to the risk assessment of exposure to metals (cadmium, lead and nickel) using data from a region in France (Nord-Pas-de-Calais). The considered exposure pathways include the atmospheric contaminant inhalation and ingestion of soil, vegetation, meat, egg, milk, fish and drinking water. Exposure scenarios are defined for different reference groups (age, dietary properties, and the fraction of food produced locally). The two largest risks correspond to an ancient industrial site (Metaleurop) and the Lille agglomeration. In these areas, cadmium, vegetation ingestion and soil contamination are the principal determinants of the computed risk. -- Highlights: ► We present a multimedia exposure model for mapping environmental disparities. ► We perform a risk assessment on a region of France at a fine scale for three metals. ► We examine exposure determinants and detect vulnerable population. ► The largest

  11. Children's exposure to polybrominated diphenyl ethers.

    Science.gov (United States)

    Zuurbier, Moniek; Leijs, Marike; Schoeters, Greet; ten Tusscher, Gavin; Koppe, Janna G

    2006-10-01

    Polybrominated biphenyl ethers (PBDEs), a class of brominated flame retardants, are frequently used in consumer products. PBDEs levels in environmental and human samples have increased in recent decades. Children are exposed to PBDEs through diet, mainly through fish, meat and milk. Total dietary exposure of children in Europe was calculated to be 2-3 ng/kg b.w./day. For nursing infants the main source of PBDE exposure is breast milk; exposure levels are around 15 ng/kg b.w./day. PBDE exposure levels in North America are 10 to a 100 times higher. Because of their persistence and their similarity to polychlorinated biphenyls (PCBs), concern has been raised about the effects of PBDEs on human health. Exposure to penta- and octa-BDE led to learning impairment and impaired motor behaviour in rodents. Exposure to penta-, octa- and also deca-BDE caused effects on thyroid homeostasis in animals. The EU has banned the production and use of penta- and octa-BDE since 2004; however, exposure will continue during the coming decades. Based upon current toxicological evidence, human exposure to deca-BDEs is not expected to lead to health effects, but data on exposure to deca-BDE and data on toxicity of deca-BDE are scarce. Therefore, monitoring studies and toxicity studies on deca-BDEs and other BDEs should continue.

  12. Human Exposure Assessment for Air Pollution.

    Science.gov (United States)

    Han, Bin; Hu, Li-Wen; Bai, Zhipeng

    2017-01-01

    Assessment of human exposure to air pollution is a fundamental part of the more general process of health risk assessment. The measurement methods for exposure assessment now include personal exposure monitoring, indoor-outdoor sampling, mobile monitoring, and exposure assessment modeling (such as proximity models, interpolation model, air dispersion models, and land-use regression (LUR) models). Among these methods, personal exposure measurement is considered to be the most accurate method of pollutant exposure assessment until now, since it can better quantify observed differences and better reflect exposure among smaller groups of people at ground level. And since the great differences of geographical environment, source distribution, pollution characteristics, economic conditions, and living habits, there is a wide range of differences between indoor, outdoor, and individual air pollution exposure in different regions of China. In general, the indoor particles in most Chinese families comprise infiltrated outdoor particles, particles generated indoors, and a few secondary organic aerosol particles, and in most cases, outdoor particle pollution concentrations are a major contributor to indoor concentrations in China. Furthermore, since the time, energy, and expense are limited, it is difficult to measure the concentration of pollutants for each individual. In recent years, obtaining the concentration of air pollutants by using a variety of exposure assessment models is becoming a main method which could solve the problem of the increasing number of individuals in epidemiology studies.

  13. Occupational blood exposure among health care workers: II. Exposure mechanisms and universal precautions

    DEFF Research Database (Denmark)

    Nelsing, S; Nielsen, T L; Nielsen, Jens Ole

    1993-01-01

    We investigated mechanisms of mucocutaneous exposure (MCE) and percutaneous exposure (PCE) to blood, and compliance with protective barriers among all former and presently employed medical staff at a Danish Department of Infectious Diseases. All subjects were asked to complete an anonymous...

  14. Video exposure monitoring as part of a strategy to assess exposure to nanoparticles

    NARCIS (Netherlands)

    Beurskens-Comuth, P.A.W.V.; Verbist, K.; Brouwer, D.

    2011-01-01

    Objectives: There is a growing awareness of the potential risks for human health of exposure to ultrafine particles or nanoparticles. In that context, workplace air measurements become important, and various strategies have been developed to monitor exposure. In addition, observations and

  15. Constant exposure technique in industrial radiography

    International Nuclear Information System (INIS)

    Domanus, J.C.

    1983-08-01

    The principles and advantages of the constant exposure technique are explained. Choice of exposure factors is analyzed. Film, paper and intensifying screens used throughout the investigation and film and paper processing are described. Exposure technique and the use of image quality indicators are given. Methods of determining of radiographic image quality are presented. Conclusions about the use of constant exposure vs. constant kilovoltage technique are formulated. (author)

  16. Economic Exposure and Integrated Risk Management

    OpenAIRE

    Miller, Kent D.

    1994-01-01

    Most corporate risk management research focuses on particular risk exposures to the exclusion of other interrelated exposures. By contrast, this study models corporate risk exposures using a multivariate approach integrating the distinct exposures of interest to finance and strategy researchers. The paper addresses the implications of multivariate modeling for corporate risk management, some key methodological issues arising in empirical estimation of corporate economic exposrues, and direc...

  17. SHEDS-HT: an integrated probabilistic exposure model for prioritizing exposures to chemicals with near-field and dietary sources.

    Science.gov (United States)

    Isaacs, Kristin K; Glen, W Graham; Egeghy, Peter; Goldsmith, Michael-Rock; Smith, Luther; Vallero, Daniel; Brooks, Raina; Grulke, Christopher M; Özkaynak, Halûk

    2014-11-04

    United States Environmental Protection Agency (USEPA) researchers are developing a strategy for high-throughput (HT) exposure-based prioritization of chemicals under the ExpoCast program. These novel modeling approaches for evaluating chemicals based on their potential for biologically relevant human exposures will inform toxicity testing and prioritization for chemical risk assessment. Based on probabilistic methods and algorithms developed for The Stochastic Human Exposure and Dose Simulation Model for Multimedia, Multipathway Chemicals (SHEDS-MM), a new mechanistic modeling approach has been developed to accommodate high-throughput (HT) assessment of exposure potential. In this SHEDS-HT model, the residential and dietary modules of SHEDS-MM have been operationally modified to reduce the user burden, input data demands, and run times of the higher-tier model, while maintaining critical features and inputs that influence exposure. The model has been implemented in R; the modeling framework links chemicals to consumer product categories or food groups (and thus exposure scenarios) to predict HT exposures and intake doses. Initially, SHEDS-HT has been applied to 2507 organic chemicals associated with consumer products and agricultural pesticides. These evaluations employ data from recent USEPA efforts to characterize usage (prevalence, frequency, and magnitude), chemical composition, and exposure scenarios for a wide range of consumer products. In modeling indirect exposures from near-field sources, SHEDS-HT employs a fugacity-based module to estimate concentrations in indoor environmental media. The concentration estimates, along with relevant exposure factors and human activity data, are then used by the model to rapidly generate probabilistic population distributions of near-field indirect exposures via dermal, nondietary ingestion, and inhalation pathways. Pathway-specific estimates of near-field direct exposures from consumer products are also modeled

  18. Epidemic gasoline exposures following Hurricane Sandy.

    Science.gov (United States)

    Kim, Hong K; Takematsu, Mai; Biary, Rana; Williams, Nicholas; Hoffman, Robert S; Smith, Silas W

    2013-12-01

    Major adverse climatic events (MACEs) in heavily-populated areas can inflict severe damage to infrastructure, disrupting essential municipal and commercial services. Compromised health care delivery systems and limited utilities such as electricity, heating, potable water, sanitation, and housing, place populations in disaster areas at risk of toxic exposures. Hurricane Sandy made landfall on October 29, 2012 and caused severe infrastructure damage in heavily-populated areas. The prolonged electrical outage and damage to oil refineries caused a gasoline shortage and rationing unseen in the USA since the 1970s. This study explored gasoline exposures and clinical outcomes in the aftermath of Hurricane Sandy. Prospectively collected, regional poison control center (PCC) data regarding gasoline exposure cases from October 29, 2012 (hurricane landfall) through November 28, 2012 were reviewed and compared to the previous four years. The trends of gasoline exposures, exposure type, severity of clinical outcome, and hospital referral rates were assessed. Two-hundred and eighty-three gasoline exposures were identified, representing an 18 to 283-fold increase over the previous four years. The leading exposure route was siphoning (53.4%). Men comprised 83.0% of exposures; 91.9% were older than 20 years of age. Of 273 home-based calls, 88.7% were managed on site. Asymptomatic exposures occurred in 61.5% of the cases. However, minor and moderate toxic effects occurred in 12.4% and 3.5% of cases, respectively. Gastrointestinal (24.4%) and pulmonary (8.4%) symptoms predominated. No major outcomes or deaths were reported. Hurricane Sandy significantly increased gasoline exposures. While the majority of exposures were managed at home with minimum clinical toxicity, some patients experienced more severe symptoms. Disaster plans should incorporate public health messaging and regional PCCs for public health promotion and toxicological surveillance.

  19. Radiation exposure of uranium mill workers

    International Nuclear Information System (INIS)

    Jha, Giridhar; Saha, S.C.

    1982-01-01

    The uranium mill workers at Jaduguda were covered by a regular film badge service from 1969 onwards. Since the log normal plot is useful in interpreting occupational exposure, a statistical analysis of the radiation exposure data was attempted. Exposure data for each year has been plotted as cumulative percentage and worker's population with exposure levels in different class intervals. The plot for each of the year under investigation shows an occupational exposure distribution more or less consistent with the log normal distribution function. The analysis shows that more than 98% of radiation workers received less than 200 mrem (2 mSv). (author)

  20. Radiation exposure during equine radiography

    International Nuclear Information System (INIS)

    Ackerman, N.; Spencer, C.P.; Hager, D.A.; Poulos, P.W. Jr.

    1988-01-01

    All personnel present in the X-ray examination room during equine radiography were monitored using low energy direct reading ionization chambers (pockets dosimeters) worn outside the lead apron at neck level. The individuals' task and dosimeter readings were recorded after each examination. Average doses ranged from 0 to 6 mrad per study. The greatest exposures were associated with radiography of the shoulder and averaged less than 4 mrad. The individual extending the horse's limb was at greatest risk although the individual holding the horse's halter and the one making the X-ray exposure received similar exposures. A survey of the overhead tube assembly used for some of the X-ray examinations also was performed. Meter readings obtained indicated an asymetric dose distribution around the tube assembly, with the highest dose occurring on the side to which the exposure cord was attached. Although the exposures observed were within acceptable limits for occupational workers, we have altered our protocol and no longer radiograph the equine shoulder unless the horse is anesthetized. Continued use of the pocket dosimeters and maintenance of a case record of radiation exposure appears to make the technologists more aware of radiation hazards

  1. Environmental radioactivity and radiation exposure

    International Nuclear Information System (INIS)

    1976-01-01

    The environmental radioactivity in the Federal Republic of Germany was almost as high in 1976 as in 1975. It only increased temporarily in autumn 1976 as a result of the above-ground nuclear weapons test of the People's Republic of China on September 29th 1976 and then returned to its previous level. The radioactivity in food had a slight decreasing trend in 1976, apart from a temporary increase in the radioactivity in milk also caused by the nuclear weapons test mentioned. The population exposure remains basically unchanged in 1976 compared with 1975. The artificial radiation exposure is about half as high as the natural radiation exposure to which man has always been exposed. The former is based to 83% on using X-rays in medicine, particularly for X-ray diagnostic purposes. The population exposure due to nuclear power plants and other nuclear plants is still well below 1% of the natural radiation exposure although in 1976 three new nuclear power plants were put into operation. This is also true for the average radiation exposure within an area of 3 km around the nuclear plant. (orig.) [de

  2. Sources of radiation exposure - an overview

    International Nuclear Information System (INIS)

    Mason, G.C.

    1990-01-01

    Sources of radiation exposure are reviewed from the perspective of mining and milling of radioactive ores in Australia. The major sources of occupational and public exposure are identified and described, and exposures from mining and milling operations are discussed in the context of natural radiation sources and other sources arising from human activities. Most radiation exposure of humans comes from natural sources. About 80% of the world average of the effective dose equivalents received by individual people arises from natural radiation, with a further 15-20% coming from medical exposures*. Exposures results from human activities, such as mining and milling of radioactive ores, nuclear power generation, fallout from nuclear weapons testing and non-medical use of radioisotopes and X-rays, add less than 1% to the total. 9 refs., 4 tabs., 10 figs

  3. Skin exposure to isocyanates: reasons for concern.

    Science.gov (United States)

    Bello, Dhimiter; Herrick, Christina A; Smith, Thomas J; Woskie, Susan R; Streicher, Robert P; Cullen, Mark R; Liu, Youcheng; Redlich, Carrie A

    2007-03-01

    Isocyanates (di- and poly-), important chemicals used worldwide to produce polyurethane products, are a leading cause of occupational asthma. Respiratory exposures have been reduced through improved hygiene controls and the use of less-volatile isocyanates. Yet isocyanate asthma continues to occur, not uncommonly in settings with minimal inhalation exposure but opportunity for skin exposure. In this review we evaluate the potential role of skin exposure in the development of isocyanate asthma. We reviewed the published animal and human literature on isocyanate skin-exposure methods, workplace skin exposure, skin absorption, and the role of skin exposure in isocyanate sensitization and asthma. We selected relevant articles from computerized searches on Medline, U.S. Environmental Protection Agency, Occupational Safety and Health Administration, National Institute for Occupational Safety and Health, and Google databases using the keywords "isocyanate," "asthma," "skin," "sensitization," and other synonymous terms, and our own extensive collection of isocyanate publications. Isocyanate production and use continues to increase as the polyurethane industry expands. There is substantial opportunity for isocyanate skin exposure in many work settings, but such exposure is challenging to quantify and continues to be underappreciated. Isocyanate skin exposure can occur at work, even with the use of personal protective equipment, and may also occur with consumer use of certain isocyanate products. In animals, isocyanate skin exposure is an efficient route to induce sensitization, with subsequent inhalation challenge resulting in asthma-like responses. Several lines of evidence support a similar role for human isocyanate skin exposure, namely, that such exposure occurs and can contribute to the development of isocyanate asthma in certain settings, presumably by inducing systemic sensitization. Integrated animal and human research is needed to better understand the role of skin

  4. Radiation exposure from incorporated isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Beleznay, F [Hungarian Academy of Sciences, Budapest. Central Research Inst. for Physics

    1985-01-01

    Recommendations for the limitation of the burden of the human body from radiation exposure were developed to avoid direct radiation health damage such that the occurrence of stochastic damage can be held below a resonable risk level. The recommendations, published under ICRP 26 and ICRP 30, contain several guidelines and concepts which are discussed here. They include the primary internal dose exposure limits, secondary and implied limits for the monitoring of internal radiation exposure (Annual Limit of Intake, Derived Air Concentrations). Methods are presented for inspection and monitoring of internal exposure in medical laboratories, inspection of incorporation of sup(131)I and sup(99m)Tc.

  5. The relationships between short-term exposure to particulate matter and mortality in Korea: impact of particulate matter exposure metrics for sub-daily exposures

    International Nuclear Information System (INIS)

    Son, Ji-Young; Bell, Michelle L

    2013-01-01

    Most studies of short-term particulate matter (PM) exposure use 24 h averages. However, other pollutants have stronger effects in shorter timeframes, which has influenced policy (e.g., ozone 8 h maximum). The selection of appropriate exposure timeframes is important for effective regulation. The US EPA identified health effects for sub-daily PM exposures as a critical research need. Unlike most areas, Seoul, Korea has hourly measurements of PM 10 , although not PM 2.5 . We investigated PM 10 and mortality (total, cardiovascular, respiratory) in Seoul (1999–2009) considering sub-daily exposures: 24 h, daytime (7 am–8 pm), morning (7–10 am), nighttime (8 pm–7 am), and 1 h daily maximum. We applied Poisson generalized linear modeling adjusting for temporal trends and meteorology. All PM 10 metrics were significantly associated with total mortality. Compared to other exposure timeframes, morning exposure had the most certain effect on total mortality (based on statistical significance). Increases of 10 μg m −3 in 24 h, daytime, morning, nighttime, and 1 h maximum PM 10 were associated with 0.15% (95% confidence interval 0.02–0.28%), 0.14% (0.01–0.27%), 0.10% (0.03–0.18%), 0.12% (0.03–0.22%), and 0.10% (0.00–0.21%) increases in total mortality, respectively. PM 10 was significantly associated with cardiovascular mortality for 24 h, morning, and nighttime exposures. We did not identify significant associations with respiratory mortality. The results support use of a 24 h averaging time as an appropriate metric for health studies and regulation, particularly for PM 10 and mortality. (letter)

  6. Estimating Contact Exposure in Football Using the Head Impact Exposure Estimate

    OpenAIRE

    Kerr, Zachary Y.; Littleton, Ashley C.; Cox, Leah M.; DeFreese, J.D.; Varangis, Eleanna; Lynall, Robert C.; Schmidt, Julianne D.; Marshall, Stephen W.; Guskiewicz, Kevin M.

    2015-01-01

    Over the past decade, there has been significant debate regarding the effect of cumulative subconcussive head impacts on short and long-term neurological impairment. This debate remains unresolved, because valid epidemiological estimates of athletes' total contact exposure are lacking. We present a measure to estimate the total hours of contact exposure in football over the majority of an athlete's lifespan. Through a structured oral interview, former football players provided information rel...

  7. Occupational blood exposure among health care workers: II. Exposure mechanisms and universal precautions

    DEFF Research Database (Denmark)

    Nelsing, S; Nielsen, T L; Nielsen, Jens Ole

    1993-01-01

    We investigated mechanisms of mucocutaneous exposure (MCE) and percutaneous exposure (PCE) to blood, and compliance with protective barriers among all former and presently employed medical staff at a Danish Department of Infectious Diseases. All subjects were asked to complete an anonymous questi...

  8. Medical exposure and the effects of radiation

    International Nuclear Information System (INIS)

    Okuyama, Chio

    2011-01-01

    Radiation gives cracks to genes. The influence is divided into deterministic effect with a threshold value, and the stochastic effect (tumor and genetic effect) which increases according to the exposure amount. Although we are put to various non-artificial radiations, which we cannot be avoided, on the earth, the contamination by artificial radiation can be defended. Artificial radioactive exposure includes medical exposure and non-medical exposure for example by nuclear power plant. As to medical examinations using radiation, the inquiry about the radiation exposure is increasing after the occurrence of the first nuclear power plant disaster of Fukushima. While concern about non-medical radioactive exposure increases, the uneasiness to medical irradiation is also increasing. The dose limit by artificial radioactive exposure other than medical exposure is set up in order to prevent the influence on the health. While the dose limit of the public exposure is set to the lower value than the total dose of non-artificial exposure concerning of a safety margin for all people, the dose limit of medical exposure is not defined, since it is thought that medical irradiation has a benefit for those who receive irradiation. Making an effort to decrease the radiation dose in performing the best medical treatment is the responsibility with which we are burdened. (author)

  9. 78 FR 41853 - Safety Advisory Guidance: Heating Rail Tank Cars To Prepare Hazardous Material for Unloading or...

    Science.gov (United States)

    2013-07-12

    ... rail tank car due to chemical self-reaction and expansion of the toluene diisocyanate matter wastes. On...: Cheryl West Freeman, Division of Engineering and Research, Pipeline and Hazardous Materials Safety... catastrophically ruptured at a transfer station at the BASF Corporation chemical facility in Freeport, Texas. The...

  10. Use of porous polyurethanes for meniscal reconstruction and meniscal prostheses

    NARCIS (Netherlands)

    deGroot, JH; deVrijer, R; Pennings, AJ; Veth, RPH; Jansen, HWB

    In the past, porous materials made of an aromatic polyurethane (PU) were successfully used for meniscal reconstruction in dogs. Since aromatic PUs yield very toxic fragments upon degradation, a linear PU was synthesized by curing a poly(epsilon-caprolactone) and 1,4-trans-cyclohexane diisocyanate I

  11. Completing the Link between Exposure Science and Toxicology for Improved Environmental Health Decision Making: The Aggregate Exposure Pathway Framework.

    Science.gov (United States)

    Teeguarden, Justin G; Tan, Yu-Mei; Edwards, Stephen W; Leonard, Jeremy A; Anderson, Kim A; Corley, Richard A; Kile, Molly L; Simonich, Staci M; Stone, David; Tanguay, Robert L; Waters, Katrina M; Harper, Stacey L; Williams, David E

    2016-05-03

    Driven by major scientific advances in analytical methods, biomonitoring, computation, and a newly articulated vision for a greater impact in public health, the field of exposure science is undergoing a rapid transition from a field of observation to a field of prediction. Deployment of an organizational and predictive framework for exposure science analogous to the "systems approaches" used in the biological sciences is a necessary step in this evolution. Here we propose the aggregate exposure pathway (AEP) concept as the natural and complementary companion in the exposure sciences to the adverse outcome pathway (AOP) concept in the toxicological sciences. Aggregate exposure pathways offer an intuitive framework to organize exposure data within individual units of prediction common to the field, setting the stage for exposure forecasting. Looking farther ahead, we envision direct linkages between aggregate exposure pathways and adverse outcome pathways, completing the source to outcome continuum for more meaningful integration of exposure assessment and hazard identification. Together, the two frameworks form and inform a decision-making framework with the flexibility for risk-based, hazard-based, or exposure-based decision making.

  12. Paternal Exposures and Pregnancy

    Science.gov (United States)

    ... increased risk for birth defects. Can the father’s workplace exposures affect my pregnancy? There have been a number of studies looking ... else could a father’s work exposure affect a pregnancy? Men exposed to ... chemicals in the workplace may carry these agents on their clothes and ...

  13. Linking Expert Judgement and Trends in Occupational Exposure into a Job-Exposure Matrix for Historical Exposure to Asbestos in The Netherlands

    NARCIS (Netherlands)

    Swuste, P.; Dahhan, M.; Burdorf, A.

    2008-01-01

    The aim of this article was to describe the structure and content of a job-exposure matrix (JEM) for historical asbestos exposure in The Netherlands. The JEM contained 309 occupational job title groups in 70 branches of industry during 10 periods of 5 years during 1945– 1994, resulting in 3090

  14. Linking expert judgement and trends in occupational exposure into a job-exposure matrix for historical exposure to asbestos in The Netherlands

    NARCIS (Netherlands)

    P. Swuste (Paul); M. Dahhan; A. Burdorf (Alex)

    2008-01-01

    textabstractThe aim of this article was to describe the structure and content of a job-exposure matrix (JEM) for historical asbestos exposure in The Netherlands. The JEM contained 309 occupational job title groups in 70 branches of industry during 10 periods of 5 years during 1945-1994, resulting in

  15. [Exposure to addictogenic substances, conditioned response and treatment of the exposure with response prevention].

    Science.gov (United States)

    Khazaal, Y; Frésard, E; Zullino, D

    2007-01-01

    Exposure to drugs or related cues is associated with psycho-physiological reactivity. These responses are conditioned during periods of active consumption. Exposure with response prevention (EPR) is a treatment established for anxiety disorder and aims to reduce anxiety by an extinction of previously conditioned responses. The conditioning recognized in additive processes has led to research into EPR's therapeutic potential for treating addiction. This paper is a review of the main studies on reactivity to cues, and EPR, particularly with respect to addiction to alcohol, opiates, cocaine and tobacco. This review is based on information from the Medline database, dealing with cue reactivity, attentional bias during exposure to cues and exposure treatment for addiction in general and, in particular, for each of the aforementioned substances. Exposure to drug-related cues is clearly associated with psycho-physiological reactivity and with attentional bias. Those phenomena are associated with craving and more difficulty in maintaining abstinence. The subject's attention is thus held by a large number of drug-related environmental stimuli. These observations are linked with conditioning phenomena and suggest the possibility of treatment by EPR conditioning extinction procedures. EPR has been most widely studied for abuse and alcohol addiction. Case reports give favourable outcomes. Results from controlled studies are less clear. Studies on patients addicted to cocaine or heroine are still limited and not conclusive. Different controlled studies on EPR for nicotine addiction have not produced conclusions in favour of this treatment. Generally, the EPR procedures used vary among studies. Studies focussing particularly on the evolution of physiological responses in a laboratory setting after EPR have demonstrated reduced autonomic nervous system activity. These results do not consistently lead to a reduction in consumption behaviour and in craving when the patient is in

  16. Metal dust exposure and lung function deterioration among steel workers: an exposure-response relationship.

    Science.gov (United States)

    Hamzah, Nurul Ainun; Mohd Tamrin, Shamsul Bahri; Ismail, Noor Hassim

    2016-07-01

    Metallic dust is a heterogeneous substance with respiratory sensitizing properties. Its long term exposure adversely affected lung function, thus may cause acute or chronic respiratory diseases. A cross-sectional study was conducted in a steel factory in Terengganu, Malaysia to assess the metal dust exposure and its relationship to lung function values among 184 workers. Metal dust concentrations values (Co, Cr, and Ni) for each worker were collected using air personal sampling. Lung function values (FEV 1 , FVC, and %FEV 1 /FVC) were determined using spirometer. Exposure to cobalt and chromium were 1-3 times higher than permissible exposure limit (PEL) while nickel was not exceeding the PEL. Cumulative of chromium was the predictor to all lung function values (FEV 1 , FVC, and %FEV 1 /FVC). Frequency of using mask was positively associated with FVC (Adj b = 0.263, P = 0.011) while past respiratory illnesses were negatively associated with %FEV 1 /FVC (Adj b = -1.452, P = 0.026). Only few workers (36.4%) were found to wear their masks all times during the working hours. There was an exposure-response relationship of cumulative metal dust exposure with the deterioration of lung function values. Improvement of control measures as well as proper and efficient use or personal protection equipment while at work could help to protect the respiratory health of workers.

  17. Minimizing radiation exposure during percutaneous nephrolithotomy.

    Science.gov (United States)

    Chen, T T; Preminger, G M; Lipkin, M E

    2015-12-01

    Given the recent trends in growing per capita radiation dose from medical sources, there have been increasing concerns over patient radiation exposure. Patients with kidney stones undergoing percutaneous nephrolithotomy (PNL) are at particular risk for high radiation exposure. There exist several risk factors for increased radiation exposure during PNL which include high Body Mass Index, multiple access tracts, and increased stone burden. We herein review recent trends in radiation exposure, radiation exposure during PNL to both patients and urologists, and various approaches to reduce radiation exposure. We discuss incorporating the principles of As Low As reasonably Achievable (ALARA) into clinical practice and review imaging techniques such as ultrasound and air contrast to guide PNL access. Alternative surgical techniques and approaches to reducing radiation exposure, including retrograde intra-renal surgery, retrograde nephrostomy, endoscopic-guided PNL, and minimally invasive PNL, are also highlighted. It is important for urologists to be aware of these concepts and techniques when treating stone patients with PNL. The discussions outlined will assist urologists in providing patient counseling and high quality of care.

  18. Natural background radiation exposures world-wide

    International Nuclear Information System (INIS)

    Bennett, B.G.

    1993-01-01

    The average radiation dose to the world's population from natural radiation sources has been assessed by UNSCEAR to be 2.4 mSv per year. The components of this exposure, methods of evaluation and, in particular, the variations in the natural background levels are presented in this paper. Exposures to cosmic radiation range from 0.26 mSv per year at sea level to 20 times more at an altitude of 6000 m. Exposures to cosmogenic radionuclides ( 3 H, 14 C) are relatively insignificant and little variable. The terrestrial radionuclides 40 K, 238 U, and 232 Th and the decay products of the latter two constitute the remainder of the natural radiation exposure. Wide variations in exposure occur for these components, particularly for radon and its decay products, which can accumulate to relatively high levels indoors. Unusually high exposures to uranium and thorium series radionuclides characterize the high natural background areas which occur in several localized regions in the world. Extreme values in natural radiation exposures have been estimated to range up to 100 times the average values. (author). 15 refs, 3 tabs

  19. Use of dose constraints in medical exposure

    International Nuclear Information System (INIS)

    Mutanga, N. V. T.

    2013-04-01

    Medical-related radiation is the largest source of controllable radiation exposure to humans and it accounts for more than 95% of radiation exposure from man-made sources. Medical exposure to radiation is exposure incurred by patients as part of their own medical or dental diagnosis or treatment; by persons, other than those occupationally exposed, knowingly, while voluntarily helping in the support and comfort of patients; and by volunteers in a programme of biomedical research involving their exposure. Because it is planned exposure, medical exposure has to conform to a set of principles of protection that apply equally to all controllable exposure situations: the principle of justification, the principle of optimisation of protection, and the principle of application of limits on maximum doses in planned situations. In this study the concept of dose constraints is being scrutinized to see if it can be applied in medical exposures and the benefits of such restrictions. Dose constraints can only be applied to exposure to persons voluntary helping in the support and comfort of patients as well as volunteers in the programme of biomedical research. There are no dose constraints for patients but the concept of reference levels applies. (au)

  20. Low-exposure tritium radiotoxicity in mammals

    International Nuclear Information System (INIS)

    Dobson, R.L.

    1982-01-01

    Studies of tritium radiotoxicity involving chronic 3 H0H exposures in mammals demonstrate in both mice and monkeys that biological effects can be measured following remarkably low levels of exposure - levels in the range of serious practical interest to radiation protection. These studies demonstrate also that deleterious effects of 3 H beta radiation do not differ significantly from those of gamma radiation at high exposures. In contrast, however, at low exposures tritium is significantly more effective than gamma rays, rad for rad, by a factor approaching 3. This is important for hazard evaluation and radiation protection because knowledge concerning biological effects of chronic low-level radiation exposure has come mainly from gamma-ray data; and predictions based on gamma-ray data will underestimate tritium effects - especially at low exposures - unless the RBE is fully taken into account

  1. Rabies exposures, post-exposure prophylaxis and deaths in a region of endemic canine rabies.

    Directory of Open Access Journals (Sweden)

    Katie Hampson

    Full Text Available Thousands of human deaths from rabies occur annually despite the availability of effective vaccines following exposure, and for disease control in the animal reservoir. Our aim was to assess risk factors associated with exposure and to determine why human deaths from endemic canine rabies still occur.Contact tracing was used to gather data on rabies exposures, post-exposure prophylaxis (PEP delivered and deaths in two rural districts in northwestern Tanzania from 2002 to 2006. Data on risk factors and the propensity to seek and complete courses of PEP was collected using questionnaires. Exposures varied from 6-141/100,000 per year. Risk of exposure to rabies was greater in an area with agropastoralist communities (and larger domestic dog populations than an area with pastoralist communities. Children were at greater risk than adults of being exposed to rabies and of developing clinical signs. PEP dramatically reduced the risk of developing rabies (odds ratio [OR] 17.33, 95% confidence interval [CI] 6.39-60.83 and when PEP was not delivered the risks were higher in the pastoralist than the agro-pastoralist area (OR 6.12, 95% CI 2.60-14.58. Low socioeconomic class and distance to medical facilities lengthened delays before PEP delivery. Over 20% of rabies-exposed individuals did not seek medical treatment and were not documented in official records and <65% received PEP. Animal bite injury records were an accurate indicator of rabies exposure incidence.Insufficient knowledge about rabies dangers and prevention, particularly prompt PEP, but also wound management, was the main cause of rabies deaths. Education, particularly in poor and marginalized communities, but also for medical and veterinary workers, would prevent future deaths.

  2. Combined Toxic Exposures and Human Health: Biomarkers of Exposure and Effect

    Directory of Open Access Journals (Sweden)

    Johan Högberg

    2011-02-01

    Full Text Available Procedures for risk assessment of chemical mixtures, combined and cumulative exposures are under development, but the scientific database needs considerable expansion. In particular, there is a lack of knowledge on how to monitor effects of complex exposures, and there are few reviews on biomonitoring complex exposures. In this review we summarize articles in which biomonitoring techniques have been developed and used. Most examples describe techniques for biomonitoring effects which may detect early changes induced by many chemical stressors and which have the potential to accelerate data gathering. Some emphasis is put on endocrine disrupters acting via epigenetic mechanisms and on carcinogens. Solid evidence shows that these groups of chemicals can interact and even produce synergistic effects. They may act during sensitive time windows and biomonitoring their effects in epidemiological studies is a challenging task.

  3. Occupational dermatoses from colophony exposure

    Directory of Open Access Journals (Sweden)

    Aleš Christian Mihelač

    2015-04-01

    Full Text Available Colophony is a resin, obtained from pine trees. It has many applications in industry as well as in products for everyday life and exposure is virtually impossible to avoid. In article, we concentrate on occupational exposure, which is frequent in workers in electronics, furniture and paper industry, production of adhesives, plastics, printing ink and synthetic rubber as well as in everyone, daily in contact with products, which contain colophony, or pine wood, like carpenters and woodworkers. Main allergens are oxidation products of abietic-type acids, but cross-reactivity with fragrances, wood resins, Balsam of Peru, wood tar and oil of turpentine is also possible. Exposure to colophony manifests itself on skin in allergic patients mainly as allergic contact dermatitis. The diagnosis is based on history of exposure, clinical presentation and epicutaneous testing. Although the only effective treatment is complete avoidance of exposure, it is difficult to avoid colophony. Consequently, prophylaxis is essential and concentrates on safe working practices, personal hygiene and protection.

  4. Occupational exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Snihs, J.O.

    1985-01-01

    An overview of occupational exposure is presented. Concepts and quantities used for radiation protection are explained as well as the ICRP system of dose limitation. The risks correlated to the limits are discussed. However, the actual exposure are often much lower than the limits and the average risk in radiation work is comparable with the average risk in other safe occupations. Actual exposures in various occupations are presented and discussed. (author)

  5. Environmental Source of Arsenic Exposure

    OpenAIRE

    Chung, Jin-Yong; Yu, Seung-Do; Hong, Young-Seoub

    2014-01-01

    Arsenic is a ubiquitous, naturally occurring metalloid that may be a significant risk factor for cancer after exposure to contaminated drinking water, cigarettes, foods, industry, occupational environment, and air. Among the various routes of arsenic exposure, drinking water is the largest source of arsenic poisoning worldwide. Arsenic exposure from ingested foods usually comes from food crops grown in arsenic-contaminated soil and/or irrigated with arsenic-contaminated water. According to a ...

  6. From dermal exposure to internal dose

    NARCIS (Netherlands)

    Sandt, J.J.M. van de; Dellarco, M.; Hemmen, J.J. van

    2007-01-01

    Exposure scenarios form an essential basis for chemical risk assessment reports under the new EU chemicals regulation REACH (Registration, Evaluation, Authorisation and restriction of Chemicals). In case the dermal route of exposure is predominant, information on both exposure and dermal

  7. Patient radiation exposure during pediatric cardiac catheterization

    International Nuclear Information System (INIS)

    Fellows, K.E.; Leibovic, S.J.

    1983-01-01

    Exposure air product (EAP) and center field entrance exposure (free-in-air) were measured in seventeen pediatric patients undergoing cardiac catheterization. Exposures were recorded separately for biplane fluoroscopy and cine angiocardiography using flat-plate ionization chambers. In the posterior-anterior (PA) projections, median EAP was 425 Roentgen-square centimeter (R-cm 2 ), with a range of 90.5-3,882 R-cm 2 ; 29-35% of this exposure occurred during cine filming. In the lateral projection, median EAP was 276 R-cm 2 (range 117-1,173); 52-59% of this exposure was due to cine filming. Median center field entrance exposure in the PA view was 7.86 Roentgens (R) with a range 2.16-73.9 of and in the lateral projection 7.39 R (range 2.64-24.6). As much as 25% of the exposure from the entire examination was contributed by manual ''test'' exposures to set cine radiographic kVp. We recommend use of testing circuits, which determine cine radiographic factors automatically and thus should lower levels of exposure

  8. Patient radiation exposure during pediatric cardiac catheterization

    International Nuclear Information System (INIS)

    Fellows, K.E.; Leibovic, S.J.

    1983-01-01

    Exposure are product (EAP) and center field entrance exposure (free-in-air) were measured in seventeen pediatric patients undergoing cardiac catheterization. Exposures were recorded separately for biplane fluoroscopy and cine angiocardiography using flat-plate ionization chambers. In the posterior-anterior (PA) projections, median EAP was 425 Roentgen-square centimeter (R-cm 2 ), with a range of 90.5-3,882 R-cm 2 ; 29-35% of this exposure occurred during cine filming. In the lateral projection, median EAP was 276 R-cm 2 (range 117-1,173); 52-59% of this exposure was due to cine filming. Median center field entrance exposure in the PA view was 7.86 Roentgens (R) with a range 2.16-73.9 of and in the lateral projection 7.39 R (range 2.64-24.6). As much as 25% of the exposure from the entire examination was contributed by manual ''test'' exposures to set cine radiographic kVp. We recommend use of testing circuits, which determine cine radiographic factors automatically and thus should lower levels of exposure. (orig.)

  9. Health impact assessment of air pollution using a dynamic exposure profile: Implications for exposure and health impact estimates

    International Nuclear Information System (INIS)

    Dhondt, Stijn; Beckx, Carolien; Degraeuwe, Bart; Lefebvre, Wouter; Kochan, Bruno; Bellemans, Tom; Int Panis, Luc; Macharis, Cathy; Putman, Koen

    2012-01-01

    In both ambient air pollution epidemiology and health impact assessment an accurate assessment of the population exposure is crucial. Although considerable advances have been made in assessing human exposure outdoors, the assessments often do not consider the impact of individual travel behavior on such exposures. Population-based exposures to NO 2 and O 3 using only home addresses were compared with models that integrate all time-activity patterns—including time in commute—for Flanders and Brussels. The exposure estimates were used to estimate the air pollution impact on years of life lost due to respiratory mortality. Health impact of NO 2 using an exposure that integrates time-activity information was on average 1.2% higher than when assuming that people are always at their home address. For ozone the overall estimated health impact was 0.8% lower. Local differences could be much larger, with estimates that differ up to 12% from the exposure using residential addresses only. Depending on age and gender, deviations from the population average were seen. Our results showed modest differences on a regional level. At the local level, however, time-activity patterns indicated larger differences in exposure and health impact estimates, mainly for people living in more rural areas. These results suggest that for local analyses the dynamic approach can contribute to an improved assessment of the health impact of various types of pollution and to the understanding of exposure differences between population groups. - Highlights: ► Exposure to ambient air pollution was assessed integrating population mobility. ► This dynamic exposure was integrated into a health impact assessment. ► Differences between the dynamic and residential exposure were quantified. ► Modest differences in health impact were found at a regional level. ► At municipal level larger differences were found, influenced by gender and age.

  10. The mere exposure effect for consumer products as a consequence of existing familiarity and controlled exposure.

    Science.gov (United States)

    Hekkert, Paul; Thurgood, Clementine; Whitfield, T W Allan

    2013-10-01

    The finding that repeated exposure to a stimulus enhances attitudes directed towards it is a well-established phenomenon. Despite this, the effects of exposure to products are difficult to determine given that they could have previously been exposed to participants any number of times. Furthermore, factors other than simple repeated exposure can influence affective evaluations for stimuli that are meaningful. In our first study, we examined the influence of existing familiarity with common objects and showed that the attractiveness of shapes representing common objects increases with their rated commonness. In our second study, we eliminated the effects of prior exposure by creating fictitious yet plausible products; thus, exposure frequency was under complete experimental control. We also manipulated the attention to be drawn to the products' designs by placing them in contexts where their visual appearance was stressed to be important versus contexts in which it was indicated that little attention had been paid to their design. Following mere exposure, attractiveness ratings increased linearly with exposure frequency, with the slope of the function being steeper for stimuli presented in an inconspicuous context-indicating that individuals engage in more deliberate processing of the stimuli when attention is drawn to their visual appearance. © 2013 Elsevier B.V. All rights reserved.

  11. PET radiation exposure control for nurses

    International Nuclear Information System (INIS)

    Kawabata, Yumiko; Kikuta, Daisuke; Anzai, Taku

    2005-01-01

    Recently, the number of clinical PET centers is increasing all over Japan. For this reason, the monitoring and control of radiation exposure of employees, especially nurses, in PET-dedicated clinics and institutions are becoming very important issues for their health. We measured the radiation exposure doses of the nurses working at Nishidai Diagnostic Imaging Center, and analyzed the exposure data obtained from them. The exposure doses of the nurses were found to be 4.8 to 7.1 mSv between April 2003 and March 2004. We found that the nurses were mostly exposed to radiation when they had to have contact with patients received an FDG injection or they had trouble with the FDG automatic injection system. To keep radiation exposure of nurses to a minimum we reconfirmed that a proper application of the three principles of protection against radiation exposure was vital. (author)

  12. Natural and anthropogenic radiation exposure of humans in Germany

    International Nuclear Information System (INIS)

    Koelzer, Winfried

    2016-12-01

    The contribution on natural and anthropogenic radiation exposure in Germany covers the following issues: (1) natural radiation exposure: external radiation exposure - cosmic and terrestric radiation, internal radiation exposure - primordial and cosmogenic radionuclides; radiation exposure due to sola neutrinos and geo-neutrinos. (2) Anthropogenic radiation exposure: radiation exposure in medicine, radioactivity in industrial products, radiation exposure during flights, radiation exposure due to nuclear facilities, radiation exposure due to fossil energy carriers in power generation, radiation exposure due to nuclear explosions, radiation exposure due to nuclear accidents. (3) Occupational radiation exposure in Germany: radiation monitoring with personal dosimeters in medicine and industry, dose surveillance of the aviation personal, working places with increases radiation exposure by natural radiation sources.

  13. Calculating radiation exposure and dose

    International Nuclear Information System (INIS)

    Hondros, J.

    1987-01-01

    This paper discusses the methods and procedures used to calculate the radiation exposures and radiation doses to designated employees of the Olympic Dam Project. Each of the three major exposure pathways are examined. These are: gamma irradiation, radon daughter inhalation and radioactive dust inhalation. A further section presents ICRP methodology for combining individual pathway exposures to give a total dose figure. Computer programs used for calculations and data storage are also presented briefly

  14. 10 CFR 850.24 - Exposure monitoring.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Exposure monitoring. 850.24 Section 850.24 Energy... Exposure monitoring. (a) General. The responsible employer must ensure that: (1) Exposure monitoring is... activities properly. (b) Initial monitoring. The responsible employer must perform initial monitoring in...

  15. Relevance of protection quantities in medical exposures

    International Nuclear Information System (INIS)

    Pradhan, A.S.

    2008-01-01

    International Commission on Radiological Protection (ICRP) continues to classify the exposures to radiation in three categories; namely 1- occupational exposure, 2- public exposure, and 3- medical exposure. Protection quantities are primarily meant for the regulatory purpose in radiological protection for controlling and limiting stochastic risks in occupational and public exposures. These are based on two basic assumptions of 1- linear no-threshold dose-effect relationship (LNT) at low doses and 2- long-term additivity of low doses. Medical exposure are predominantly delivered to individuals (patients) undergoing diagnostic examinations, interventional procedures and radiation therapy but also include individual caring for or comforting patients incurring exposure and the volunteers of biomedical medical research programmes. Radiation protection is as relevant to occupational and public exposure as to medical exposures except that the dose limits set for the formers are not applicable to medical exposure but reference levels and dose constrains are recommended for diagnostic and interventional medical procedures. In medical institutions, both the occupational and medical exposure takes place. Since the doses in diagnostic examinations are low, it has been observed that not only the protection quantities are often used in such cases but these are extended to estimate the number of cancer deaths due to such practices. One of the striking features of the new ICRP recommendations has been to elaborate the concepts of the dosimetric quantities. The limitation of protection quantities ((Effective dose, E=Σ RT D TR .W T .W R and Equivalent Dose H T =Σ RT D TR .W R ) have been brought out and this has raised a great concern and initiated debates on the use of these quantities in medical exposures. Consequently, ICRP has set a task group to provide more details and the recommendations. It has, therefore, became important to draw the attention of medical physics community

  16. Subliminal mere exposure: specific, general, and diffuse effects.

    Science.gov (United States)

    Monahan, J L; Murphy, S T; Zajonc, R B

    2000-11-01

    The present research examined the possibility that repeated exposure may simultaneously produce specific and diffuse effects. In Study 1, participants were presented with 5-ms exposures of 25 stimuli each shown once (single-exposure condition) or with five repetitions of 5 stimuli (repeated-exposure condition). Participants in the repeated-exposure condition subsequently rated their own mood more positively than those in the single-exposure condition. Study 2 examined whether affect generated by subliminal repeated exposures transfers to unrelated stimuli. After a subliminal exposure phase, affective reactions to previously exposed stimuli, to new but similar stimuli, and to stimuli from a different category were obtained. Previously exposed stimuli were rated most positively and novel different stimuli least positively. All stimuli were rated more positively in the repeated-exposure condition than in the single-exposure condition. These findings suggest that affect generated by subliminal repeated exposure is sufficiently diffuse to influence ratings of unrelated stimuli and mood.

  17. Synthesis and characterization of castor oil based polyurethane ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. A series of interpenetrating polymer networks (IPNs) of castor oil based polyurethane/polyacrylo- nitrile (PU/PAN: 80/20, 60/40, 50/50, 40/60 and 20/80) were synthesized by condensation reaction of castor oil with methylene diisocyanate and acrylonitrile, employing benzoyl peroxide (BPO) and ethylene glycol ...

  18. Human exposure to bisphenol A by biomonitoring: Methods, results and assessment of environmental exposures

    International Nuclear Information System (INIS)

    Dekant, Wolfgang; Voelkel, Wolfgang

    2008-01-01

    Human exposure to bisphenol A is controversially discussed. This review critically assesses methods for biomonitoring of bisphenol A exposures and reported concentrations of bisphenol A in blood and urine of non-occupationally ('environmentally') exposed humans. From the many methods published to assess bisphenol A concentrations in biological media, mass spectrometry-based methods are considered most appropriate due to high sensitivity, selectivity and precision. In human blood, based on the known toxicokinetics of bisphenol A in humans, the expected very low concentrations of bisphenol A due to rapid biotransformation and the very rapid excretion result in severe limitations in the use of reported blood levels of bisphenol A for exposure assessment. Due to the rapid and complete excretion of orally administered bisphenol A, urine samples are considered as the appropriate body fluid for bisphenol A exposure assessment. In urine samples from several cohorts, bisphenol A (as glucuronide) was present in average concentrations in the range of 1-3 μg/L suggesting that daily human exposure to bisphenol A is below 6 μg per person (< 0.1 μg/kg bw/day) for the majority of the population

  19. Human exposure to per- and polyfluoroalkyl substances (PFASs) via house dust in Korea: Implication to exposure pathway.

    Science.gov (United States)

    Tian, Zhexi; Kim, Seung-Kyu; Shoeib, Mahiba; Oh, Jeong-Eun; Park, Jong-Eun

    2016-05-15

    A wide range of per- and polyfluoroalkyl substances (PFASs), including fluorotelomer alcohols (FTOHs), perfluorooctane sulfonamidoethanols (FOSEs), perfluoroalkyl carboxylic acids (PFCAs), and perfluoroalkane sulfonic acids (PFSAs), were measured in fifteen house dust and two nonresidential indoor dust of Korea. Total concentrations of PFASs in house dust ranged from 29.9 to 97.6 ng g(-1), with a dominance of perfluorooctane sulfonic acid (PFOS), followed by 8:2 FTOH, N-Ethyl perfluorooctane sulfonamidoethanol (EtFOSE), perfluoroctanoic acid (PFOA). In a typical exposure scenario, the estimated daily intakes (EDIs) of total PFASs via house dust ingestion were 2.83 ng d(-1) for toddlers and 1.13 ng d(-1) for adults, which were within the range of the mean EDIs reported from several countries. For PFOA and PFOS exposure via house dust ingestion, indirect exposure (via precursors) was a minor contributor, accounting for 5% and 12%, respectively. An aggregated exposure (hereafter, overall-EDIs) of PFOA and PFOS occurring via all pathways, estimated using data compiled from the literature, were 53.6 and 14.8 ng d(-1) for toddlers, and 20.5 and 40.6 ng d(-1) for adults, respectively, in a typical scenario. These overall-EDIs corresponded to 82% (PFOA) and 92% (PFOS) of a pharmacokinetic model-based EDIs estimated from adults' serum data. Direct dietary exposure was a major contributor (>89% of overall-EDI) to PFOS in both toddlers and adults, and PFOA in toddlers. As for PFOA exposure of adults, however direct exposure via tap water drinking (37%) and indirect exposure via inhalation (22%) were as important as direct dietary exposure (41%). House dust-ingested exposure (direct+indirect) was responsible for 5% (PFOS in toddlers) and house-dust ingestion was a minor contributor in this study, but should not be ignored for toddlers' PFOS exposure due to its significance in the worst-case scenario. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. 30 CFR 57.5071 - Exposure monitoring.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Exposure monitoring. 57.5071 Section 57.5071... Exposure monitoring. (a) Mine operators must monitor as often as necessary to effectively determine, under... miners and their representatives with an opportunity to observe exposure monitoring required by this...

  1. AirPEx: Air Pollution Exposure Model

    NARCIS (Netherlands)

    Freijer JI; Bloemen HJTh; Loos S de; Marra M; Rombout PJA; Steentjes GM; Veen MP van; LBO

    1997-01-01

    Analysis of inhalatory exposure to air pollution is an important area of investigation when assessing the risks of air pollution for human health. Inhalatory exposure research focuses on the exposure of humans to air pollutants and the entry of these pollutants into the human respiratory tract. The

  2. Occupational Exposures and Chronic Airflow Limitation

    Directory of Open Access Journals (Sweden)

    Helen Dimich-Ward

    1996-01-01

    Full Text Available The recent literature was reviewed to evaluate whether chronic airflow limitation is associated with occupational exposures to dusts. Only those studies that controlled for the effects of smoking were included. There is compelling evidence that exposure to inorganic dusts, such as from coal and hardrock mining or asbestos, are associated with the development of chronic airflow limitation, independently of pneumoconiosis. Nonsmoking gold miners are particularly at high risk of airflow obstruction and emphysema. Findings from studies of organic dusts, such as exposures to wood, cotton, grain or other agricultural dusts, or to mixed dust exposures, were less consistent but tended to show positive dose-response associations. In the majority of studies, no statistical interaction was shown between dust exposures and smoking; however, the effects of the dust exposures were often more pronounced. An occupational history should be considered, in addition to a smoking history, as an integral part of an investigation of chronic airflow limitation in a patient.

  3. Radon exposure in uranium mining industry vs. exposure in tourist caves

    International Nuclear Information System (INIS)

    Quindos Poncela, L.; Fernandez Navarro, P.; Sainz Fernandez, C.; Gomez Arozamena, J.; Bordonoba Perez, M.

    2004-01-01

    There is a fairly general consensus among health physicists and radiation professionals that exposure to radon progeny is the largest and most variable contribution to the population's exposure to natural sources of radiation. However, this exposure is the subject of continuing debate concerning the validity of risk assessment and recommendations on how to act in radon-prone areas. The purpose of this contribution is to situate the radon issue in Spain in two very different settings. The first is a uranium mining industry located in Saelices el Chico (Salamanca), which is under strict control of the Spanish Nuclear Safety Council (CSN). We have measured radon concentrations in different workplaces in this mine over a five-year period. The second setting comprises four tourist caves, three of which are located in the province of Cantabria and the fourth on the Canary Island of Lanzarote. These caves are not subject to any administrative control of radiation exposure. Measured air 222 Rn concentrations were used to estimate annual effective doses due to radon inhalation in the two settings, and dose values were found to be from 2 to 10 times lower in the uranium mine than in the tourist caves. These results were analysed in the context of the new European Basic Safety Standards Directive (EU-BSS, 1996). (authors)

  4. An Exposure Assessment of Polybrominated Diphenyl Ethers ...

    Science.gov (United States)

    EPA announced the availability of the final report, An Exposure Assessment of Polybrominated Diphenyl Ethers. This report provides a comprehensive assessment of the exposure of Americans to this class of persistent organic pollutants. Individual chapters in this document address: the production, use, and lifecycle of PBDEs; environmental fate; environmental levels; and human exposure. This final report addresses the exposure assessment needs identified in the OPBDE Workgroup project plan. It provides a comprehensive assessment of the exposure of Americans to this class of persistent organic pollutants. Individual chapters in this document address: the production, use, and lifecycle of PBDEs; environmental fate; environmental levels; and human exposure.

  5. Oral Chromium Exposure and Toxicity

    Science.gov (United States)

    Sun, Hong; Brocato, Jason

    2015-01-01

    Hexavalent chromium [Cr(VI)] is a known carcinogen when inhaled. However, inhalational exposure to Cr(VI) affects only a small portion of the population, mainly by occupational exposures. In contrast, oral exposure to Cr(VI) is widespread and affects many people throughout the globe. In 2008, the National Toxicology Program (NTP) released a 2-year study demonstrating that ingested Cr(VI) was carcinogenic in rats and mice. The effects of Cr(VI) oral exposure is mitigated by reduction in the gut, however a portion evades the reductive detoxification and reaches target tissues. Once Cr(VI) enters the cell, it ultimately gets reduced to Cr(III), which mediates its toxicity via induction of oxidative stress during the reduction while Cr intermediates react with protein and DNA. Cr(III) can form adducts with DNA that may lead to mutations. This review will discuss the potential adverse effects of oral exposure to Cr(VI) by presenting up-to-date human and animal studies, examining the underlying mechanisms that mediate Cr(VI) toxicity, as well as highlighting opportunities for future research. PMID:26231506

  6. Attentional Modulation of the Mere Exposure Effect

    Science.gov (United States)

    Yagi, Yoshihiko; Ikoma, Shinobu; Kikuchi, Tadashi

    2009-01-01

    The "mere exposure effect" refers to the phenomenon where previous exposures to stimuli increase participants' subsequent affective preference for those stimuli. This study explored the effect of selective attention on the mere exposure effect. The experiments manipulated the to-be-attended drawings in the exposure period (either red or green…

  7. Environmental source of arsenic exposure.

    Science.gov (United States)

    Chung, Jin-Yong; Yu, Seung-Do; Hong, Young-Seoub

    2014-09-01

    Arsenic is a ubiquitous, naturally occurring metalloid that may be a significant risk factor for cancer after exposure to contaminated drinking water, cigarettes, foods, industry, occupational environment, and air. Among the various routes of arsenic exposure, drinking water is the largest source of arsenic poisoning worldwide. Arsenic exposure from ingested foods usually comes from food crops grown in arsenic-contaminated soil and/or irrigated with arsenic-contaminated water. According to a recent World Health Organization report, arsenic from contaminated water can be quickly and easily absorbed and depending on its metabolic form, may adversely affect human health. Recently, the US Food and Drug Administration regulations for metals found in cosmetics to protect consumers against contaminations deemed deleterious to health; some cosmetics were found to contain a variety of chemicals including heavy metals, which are sometimes used as preservatives. Moreover, developing countries tend to have a growing number of industrial factories that unfortunately, harm the environment, especially in cities where industrial and vehicle emissions, as well as household activities, cause serious air pollution. Air is also an important source of arsenic exposure in areas with industrial activity. The presence of arsenic in airborne particulate matter is considered a risk for certain diseases. Taken together, various potential pathways of arsenic exposure seem to affect humans adversely, and future efforts to reduce arsenic exposure caused by environmental factors should be made.

  8. Environmental Source of Arsenic Exposure

    Directory of Open Access Journals (Sweden)

    Jin-Yong Chung

    2014-09-01

    Full Text Available Arsenic is a ubiquitous, naturally occurring metalloid that may be a significant risk factor for cancer after exposure to contaminated drinking water, cigarettes, foods, industry, occupational environment, and air. Among the various routes of arsenic exposure, drinking water is the largest source of arsenic poisoning worldwide. Arsenic exposure from ingested foods usually comes from food crops grown in arsenic-contaminated soil and/or irrigated with arsenic-contaminated water. According to a recent World Health Organization report, arsenic from contaminated water can be quickly and easily absorbed and depending on its metabolic form, may adversely affect human health. Recently, the US Food and Drug Administration regulations for metals found in cosmetics to protect consumers against contaminations deemed deleterious to health; some cosmetics were found to contain a variety of chemicals including heavy metals, which are sometimes used as preservatives. Moreover, developing countries tend to have a growing number of industrial factories that unfortunately, harm the environment, especially in cities where industrial and vehicle emissions, as well as household activities, cause serious air pollution. Air is also an important source of arsenic exposure in areas with industrial activity. The presence of arsenic in airborne particulate matter is considered a risk for certain diseases. Taken together, various potential pathways of arsenic exposure seem to affect humans adversely, and future efforts to reduce arsenic exposure caused by environmental factors should be made.

  9. Post-exposure treatment with nasal atropine methyl bromide protects against microinstillation inhalation exposure to sarin in guinea pigs

    International Nuclear Information System (INIS)

    Che, Magnus M.; Conti, Michele; Chanda, Soma; Boylan, Megan; Sabnekar, Praveena; Rezk, Peter; Amari, Ethery; Sciuto, Alfred M.; Gordon, Richard K.; Doctor, Bhupendra P.; Nambiar, Madhusoodana P.

    2009-01-01

    We evaluated the protective efficacy of nasal atropine methyl bromide (AMB) which does not cross the blood-brain barrier against sarin inhalation exposure. Age and weight matched male guinea pigs were exposed to 846.5 mg/m 3 sarin using a microinstillation inhalation exposure technique for 4 min. The survival rate at this dose was 20%. Post-exposure treatment with nasal AMB (2.5 mg/kg, 1 min) completely protected against sarin induced toxicity (100% survival). Development of muscular tremors was decreased in animals treated with nasal AMB. Post-exposure treatment with nasal AMB also normalized acute decrease in blood oxygen saturation and heart rate following sarin exposure. Inhibition of blood AChE and BChE activities following sarin exposure was reduced in animals treated with nasal AMB, indicating that survival increases the metabolism of sarin or expression of AChE. The body weight loss of animals exposed to sarin and treated with nasal AMB was similar to saline controls. No differences were observed in lung accessory lobe or tracheal edema following exposure to sarin and subsequent treatment with nasal AMB. Total bronchoalveolar lavage fluid (BALF) protein, a biomarker of lung injury, showed trends similar to saline controls. Surfactant levels post-exposure treatment with nasal AMB returned to normal, similar to saline controls. Alkaline phosphatase levels post-exposure treatment with nasal AMB were decreased. Taken together, these data suggest that nasal AMB blocks the copious airway secretion and peripheral cholinergic effects and protects against lethal inhalation exposure to sarin thus increasing survival.

  10. 30 CFR 62.130 - Permissible exposure level.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Permissible exposure level. 62.130 Section 62... REGULATIONS OCCUPATIONAL NOISE EXPOSURE § 62.130 Permissible exposure level. (a) The mine operator must assure that no miner is exposed during any work shift to noise that exceeds the permissible exposure level. If...

  11. Double blind placebo controlled exposure to molds

    DEFF Research Database (Denmark)

    Meyer, H W; Jensen, K A; Nielsen, K F

    2005-01-01

    non-significant, and at the same level as after placebo exposure. The developed exposure system based on the Particle-Field and Laboratory Emission Cell (P-FLEC) makes it possible to deliver a precise and highly controlled dose of mold spores from water-damaged building materials, imitating realistic......The objective was to develop an experimental setup for human exposure to mold spores, and to study the clinical effect of this exposure in sensitive subjects who had previously experienced potentially building-related symptoms (BRS) at work. From three water-damaged schools eight employees....... In conclusion this is, to our knowledge, the first study to successfully conduct a human exposure to a highly controlled dose of fungal material aerosolized directly from wet building materials. This short-term exposure to high concentrations of two different molds induced no more reactions than exposure...

  12. Peripheral blood signatures of lead exposure.

    Directory of Open Access Journals (Sweden)

    Heather G LaBreche

    Full Text Available BACKGROUND: Current evidence indicates that even low-level lead (Pb exposure can have detrimental effects, especially in children. We tested the hypothesis that Pb exposure alters gene expression patterns in peripheral blood cells and that these changes reflect dose-specific alterations in the activity of particular pathways. METHODOLOGY/PRINCIPAL FINDING: Using Affymetrix Mouse Genome 430 2.0 arrays, we examined gene expression changes in the peripheral blood of female Balb/c mice following exposure to per os lead acetate trihydrate or plain drinking water for two weeks and after a two-week recovery period. Data sets were RMA-normalized and dose-specific signatures were generated using established methods of supervised classification and binary regression. Pathway activity was analyzed using the ScoreSignatures module from GenePattern. CONCLUSIONS/SIGNIFICANCE: The low-level Pb signature was 93% sensitive and 100% specific in classifying samples a leave-one-out crossvalidation. The high-level Pb signature demonstrated 100% sensitivity and specificity in the leave-one-out crossvalidation. These two signatures exhibited dose-specificity in their ability to predict Pb exposure and had little overlap in terms of constituent genes. The signatures also seemed to reflect current levels of Pb exposure rather than past exposure. Finally, the two doses showed differential activation of cellular pathways. Low-level Pb exposure increased activity of the interferon-gamma pathway, whereas high-level Pb exposure increased activity of the E2F1 pathway.

  13. Health impact assessment of air pollution using a dynamic exposure profile: Implications for exposure and health impact estimates

    Energy Technology Data Exchange (ETDEWEB)

    Dhondt, Stijn, E-mail: stijn.dhondt@vub.ac.be [Department of Medical Sociology and Health Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090, Brussels (Belgium); Beckx, Carolien, E-mail: Carolien.Beckx@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Degraeuwe, Bart, E-mail: Bart.Degraeuwe@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Lefebvre, Wouter, E-mail: Wouter.Lefebvre@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Kochan, Bruno, E-mail: Bruno.Kochan@uhasselt.be [Transportation Research Institute, Hasselt University, Wetenschapspark 5 bus 6, 3590 Diepenbeek (Belgium); Bellemans, Tom, E-mail: Tom.Bellemans@uhasselt.be [Transportation Research Institute, Hasselt University, Wetenschapspark 5 bus 6, 3590 Diepenbeek (Belgium); Int Panis, Luc, E-mail: Luc.intpanis@vito.be [Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol (Belgium); Transportation Research Institute, Hasselt University, Wetenschapspark 5 bus 6, 3590 Diepenbeek (Belgium); Macharis, Cathy, E-mail: cjmachar@vub.ac.be [Department MOSI-Transport and Logistics, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels (Belgium); Putman, Koen, E-mail: kputman@vub.ac.be [Department of Medical Sociology and Health Sciences, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090, Brussels (Belgium); Interuniversity Centre for Health Economics Research (I-CHER), Vrije Universiteit Brussel, Brussels (Belgium)

    2012-09-15

    In both ambient air pollution epidemiology and health impact assessment an accurate assessment of the population exposure is crucial. Although considerable advances have been made in assessing human exposure outdoors, the assessments often do not consider the impact of individual travel behavior on such exposures. Population-based exposures to NO{sub 2} and O{sub 3} using only home addresses were compared with models that integrate all time-activity patterns-including time in commute-for Flanders and Brussels. The exposure estimates were used to estimate the air pollution impact on years of life lost due to respiratory mortality. Health impact of NO{sub 2} using an exposure that integrates time-activity information was on average 1.2% higher than when assuming that people are always at their home address. For ozone the overall estimated health impact was 0.8% lower. Local differences could be much larger, with estimates that differ up to 12% from the exposure using residential addresses only. Depending on age and gender, deviations from the population average were seen. Our results showed modest differences on a regional level. At the local level, however, time-activity patterns indicated larger differences in exposure and health impact estimates, mainly for people living in more rural areas. These results suggest that for local analyses the dynamic approach can contribute to an improved assessment of the health impact of various types of pollution and to the understanding of exposure differences between population groups. - Highlights: Black-Right-Pointing-Pointer Exposure to ambient air pollution was assessed integrating population mobility. Black-Right-Pointing-Pointer This dynamic exposure was integrated into a health impact assessment. Black-Right-Pointing-Pointer Differences between the dynamic and residential exposure were quantified. Black-Right-Pointing-Pointer Modest differences in health impact were found at a regional level. Black

  14. Gamma radiographic exposure time indicator

    International Nuclear Information System (INIS)

    Risbud, V.H.; Thiagarajan, A.; Gangadharan, P.

    1979-01-01

    In industrial radiography, with the proper selection of source and film, the radiographic quality depends very much on the exposure time, which in turn depends upon the source strength and the source to film distance. Conventional methods to arrive at correct exposure time involve time consuming calculations and in these methods the knowledge of the above mentioned parameters is imperative. An instrument to determine the required exposure time has been developed which indicates exposure times in about 30 secs. This covers two commonly used gamma radiography sources, viz., 192 Ir and 60 Co and six commonly used radiography films of different speeds. Knowledge of source strength and source to film distance is not required with the use of this instrument. With a knowledge of the total exposure required by the film to give the required sensitivity and by the measurement of radiation level at the film location, the correct exposure time is determined. The radiation level is measured by placing a GM counter behind the radiographic specimen at the film location. To match the responses of the film and the GM counter, the counter is incorporated in a suitably designed probe. In this instruments, an integrator to integrate the GM-pulses and a constant current integrator (timer) are started simultaneously. The voltage at the GM-pulse integrator is compared with a preselected voltage, (selected on the basis of film type, source, source strength and order of object thickness) by a comparator. The comparator is so adjusted that when the GM-pulse integrator voltage exceeds the preselected voltage, it switches its state and stops the integration of constant current. The constant current integrator output which is proportional to the time taken for the GM-pulse integrator to reach the preselected voltage, is read on a meter graduated in terms of exposure time. The instrument can measure exposure times from 5 minutes to 10 hours read in two ranges, the range-changing being automatic

  15. Personal exposure to ultrafine particles.

    Science.gov (United States)

    Wallace, Lance; Ott, Wayne

    2011-01-01

    Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement periods in several homes were documented, along with 25 h of driving two cars, and 22 visits to restaurants. Cooking on gas or electric stoves and electric toaster ovens was a major source of UFP, with peak personal exposures often exceeding 100,000 particles/cm³ and estimated emission rates in the neighborhood of 10¹² particles/min. Other common sources of high UFP exposures were cigarettes, a vented gas clothes dryer, an air popcorn popper, candles, an electric mixer, a toaster, a hair dryer, a curling iron, and a steam iron. Relatively low indoor UFP emissions were noted for a fireplace, several space heaters, and a laser printer. Driving resulted in moderate exposures averaging about 30,000 particles/cm³ in each of two cars driven on 17 trips on major highways on the East and West Coasts. Most of the restaurants visited maintained consistently high levels of 50,000-200,000 particles/cm³ for the entire length of the meal. The indoor/outdoor ratios of size-resolved UFP were much lower than for PM₂.₅ or PM₁₀, suggesting that outdoor UFP have difficulty in penetrating a home. This in turn implies that outdoor concentrations of UFP have only a moderate effect on personal exposures if indoor sources are present. A time-weighted scenario suggests that for typical suburban nonsmoker lifestyles, indoor sources provide about 47% and outdoor sources about 36% of total daily UFP exposure and in-vehicle exposures add the remainder (17%). However, the effect of one smoker in the home results in an overwhelming increase in the importance of indoor sources (77% of the total).

  16. Testing of Disposable Protective Garments Against Isocyanate Permeation From Spray Polyurethane Foam Insulation.

    Science.gov (United States)

    Mellette, Michael P; Bello, Dhimiter; Xue, Yalong; Yost, Michael; Bello, Anila; Woskie, Susan

    2018-05-12

    Diisocyanates (isocyanates), including methylene diphenyl diisocyanate (MDI), are the primary reactive components of spray polyurethane foam (SPF) insulation. They are potent immune sensitizers and a leading cause of occupational asthma. Skin exposure to isocyanates may lead to both irritant and allergic contact dermatitis and possibly contribute to systemic sensitization. More than sufficient evidence exists to justify the use of protective garments to minimize skin contact with aerosolized and raw isocyanate containing materials during SPF applications. Studies evaluating the permeation of protective garments following exposure to SPF insulation do not currently exist. To conduct permeation testing under controlled conditions to assess the effectiveness of common protective gloves and coveralls during SPF applications using realistic SPF product formulations. Five common disposable garment materials [disposable latex gloves (0.07 mm thickness), nitrile gloves (0.07 mm), vinyl gloves (0.07 mm), polypropylene coveralls (0.13 mm) and Tyvek coveralls (0.13 mm)] were selected for testing. These materials were cut into small pieces and assembled into a permeation test cell system and coated with a two-part slow-rise spray polyurethane foam insulation. Glass fiber filters (GFF) pretreated with 1-(9-anthracenylmethyl)piperazine) (MAP) were used underneath the garment to collect permeating isocyanates. GFF filters were collected at predetermined test intervals between 0.75 and 20.00 min and subsequently analyzed using liquid chromatography-tandem mass spectrometry. For each garment material, we assessed (i) the cumulative concentration of total isocyanate, including phenyl isocyanate and three MDI isomers, that effectively permeated the material over the test time; (ii) estimated breakthrough detection time, average permeation rate, and standardized breakthrough time; from which (iii) recommendations were developed for the use of similar protective garments following

  17. Influence of exposure assessment and parameterization on exposure response. Aspects of epidemiologic cohort analysis using the Libby Amphibole asbestos worker cohort.

    Science.gov (United States)

    Bateson, Thomas F; Kopylev, Leonid

    2015-01-01

    Recent meta-analyses of occupational epidemiology studies identified two important exposure data quality factors in predicting summary effect measures for asbestos-associated lung cancer mortality risk: sufficiency of job history data and percent coverage of work history by measured exposures. The objective was to evaluate different exposure parameterizations suggested in the asbestos literature using the Libby, MT asbestos worker cohort and to evaluate influences of exposure measurement error caused by historically estimated exposure data on lung cancer risks. Focusing on workers hired after 1959, when job histories were well-known and occupational exposures were predominantly based on measured exposures (85% coverage), we found that cumulative exposure alone, and with allowance of exponential decay, fit lung cancer mortality data similarly. Residence-time-weighted metrics did not fit well. Compared with previous analyses based on the whole cohort of Libby workers hired after 1935, when job histories were less well-known and exposures less frequently measured (47% coverage), our analyses based on higher quality exposure data yielded an effect size as much as 3.6 times higher. Future occupational cohort studies should continue to refine retrospective exposure assessment methods, consider multiple exposure metrics, and explore new methods of maintaining statistical power while minimizing exposure measurement error.

  18. Bases for establishing radiation exposure limits

    International Nuclear Information System (INIS)

    Pochin, E.E.

    1977-01-01

    It is an essential requirement of good radiation protection that all unnecessary exposure of people should be avoided and that any necessary exposure, whether of workers or of members of the general public, should be minimized. It is, however, an additional requirement that such necessary exposures should not exceed certain stated limits. These principles are based on the possibility that even the smallest exposures may involve some risk of harm, that any risk of harm should be justifiable by the circumstances necessitating it, and that risk should always be limited to an appropriately low level. The bases for establishing exposure limits must therefore involve an assessment of the risk involved in any form of radiation exposure, and an opinion as to the degree of safety that should be ensured in circumstances which necessitate any occupational or public exposure to radiation. There is increasing quantitative evidence on the frequency on which harm, and particularly the induction of malignancies, may be caused in people exposed to radiation at high doses; and somewhat clearer bases than previously for inferring the possible frequencies at low doses. It is therefore easier to assess the degree of safety ensured by restricting radiation exposure to particular levels. It is clear also that a comparable degree of safety should be ensured whether the radiation exposure involves the whole body more of less uniformly, or individual tissues or organs selectively. The ''weighting'' factors appropriate to irradiation of particular tissues from internal emitters can thus be defined in terms of their likely individual contributions to the harm of whole-body irradiation. In this way the limits for different modes of exposure by external or internal radiation can be related so as to ensure that protection should be equally effective for different distributions of absorbed dose in the body. In particular, the over-simplified concept of a single critical organ determining the

  19. Asbestos Exposure Assessment Database

    Science.gov (United States)

    Arcot, Divya K.

    2010-01-01

    Exposure to particular hazardous materials in a work environment is dangerous to the employees who work directly with or around the materials as well as those who come in contact with them indirectly. In order to maintain a national standard for safe working environments and protect worker health, the Occupational Safety and Health Administration (OSHA) has set forth numerous precautionary regulations. NASA has been proactive in adhering to these regulations by implementing standards which are often stricter than regulation limits and administering frequent health risk assessments. The primary objective of this project is to create the infrastructure for an Asbestos Exposure Assessment Database specific to NASA Johnson Space Center (JSC) which will compile all of the exposure assessment data into a well-organized, navigable format. The data includes Sample Types, Samples Durations, Crafts of those from whom samples were collected, Job Performance Requirements (JPR) numbers, Phased Contrast Microscopy (PCM) and Transmission Electron Microscopy (TEM) results and qualifiers, Personal Protective Equipment (PPE), and names of industrial hygienists who performed the monitoring. This database will allow NASA to provide OSHA with specific information demonstrating that JSC s work procedures are protective enough to minimize the risk of future disease from the exposures. The data has been collected by the NASA contractors Computer Sciences Corporation (CSC) and Wyle Laboratories. The personal exposure samples were collected from devices worn by laborers working at JSC and by building occupants located in asbestos-containing buildings.

  20. Exposure to wet work in working Australians.

    Science.gov (United States)

    Keegel, Tessa G; Nixon, Rosemary L; LaMontagne, Anthony D

    2012-02-01

    The Australian National Hazard Exposure Worker Surveillance (NHEWS) Survey 2008 was a cross-sectional survey undertaken by Safe Work Australia to inform the development of exposure prevention initiatives for occupational disease. This is a descriptive study of workplace exposures. To assess the occupational and demographic characteristics of workers reporting exposure to wet work. Computer-assisted telephone interviews were conducted with 4500 workers. Two wet work exposure outcomes (frequent washing of hands and duration of time spent at work with the hands immersed in liquids) were analysed. The response rate for the study was 42.3%. For hand-washing, 9.8% [95% confidence interval (CI) 8.9-10.7] reported washing their hands more than 20 times per day. For immersion of hands in liquids, 4.5% (95% CI 3.9-5.1) reported immersion for more than 2 hr per day. Females were more likely to report exposure to frequent hand-washing than males [odds ratio (OR) 1.97, 95% CI 1.49-2.61]. Workers in the lowest occupational skill level jobs were more likely to report increased exposure to hands immersed in liquids than those in the highest (OR 6.41, 95% CI 3.78-10.88). Workers reporting skin exposure to chemicals were more likely to report exposure to hand-washing (OR 3.68, 95% CI 2.91-4.66) and immersion of the hands in liquids (OR 4.09, 95% CI 2.92-5.74). Specific groups of workers reported high levels of exposure to wet work. There were differences between the profiles of workers reporting frequent hand-washing and workers reporting increased duration of exposure to hands immersed in liquids. We also found a high correlation between wet work and chemical exposure. © 2011 John Wiley & Sons A/S.

  1. A new radiation exposure record system

    International Nuclear Information System (INIS)

    Lyon, M.; Berndt, V.L.; Trevino, G.W.; Oakley, B.M.

    1993-04-01

    The Hanford Radiological Records Program (HRRP) serves all Hanford contractors as the single repository for radiological exposure for all Hanford employees, subcontractors, and visitors. The program administers and preserves all Hanford radiation exposure records. The program also maintains a Radiation Protection Historical File which is a historical file of Hanford radiation protection and dosimetry procedures and practices. Several years ago DOE declared the existing UNIVAC mainframe computer obsolete and the existing Occupational Radiation Exposure (ORE) system was slated to be redeveloped. The new system named the Radiological Exposure (REX) System is described in this document

  2. Estimating Exposure of Terrestrial Wildlife to Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Sample, B.E.

    1994-01-01

    This report presents a general model for exposure of terrestrial wildlife to contaminants (Sect. 2), methods for estimating parameters of the model (Sect. 3), species specific parameters for endpoint species on the Oak Ridge Reservation (ORR) (Sect. 4), and a sample application (Sect. 5). Exposure can be defined as the coincidence in both space and time of a receptor and a stressor, such that the receptor and stressor come into contact and interact (Risk Assessment Forum 1992). In the context of ecological risk assessment, receptors include all endpoint species or communities identified for a site [see Suter (1989) and Suter et al. (1994) for discussions of ecological endpoints for waste sites]. In the context of waste site assessments, stressors are chemical contaminations, and the contact and interaction are uptake of the contaminant by the receptor. Without sufficient exposure of the receptor to the contaminants, there is no ecological risk. Unlike some other endpoint assemblages, terrestrial wildlife are significantly exposed to contaminants in multiple media. They may drink or swim in contaminated water, ingest contaminated food and soil, and breath contaminated air. In addition, because most wildlife are mobile, moving among and within habitats, exposure is not restricted to a single location. They may integrate contamination from several spatially discrete sources. Therefore, exposure models for terrestrial wildlife must include multiple media. This document provides models and parameters for estimating exposure of birds and mammals. Reptiles and amphibians are not considered because few data exist with which to assess exposure to these organisms. In addition, because toxicological data are scarce for both classes, evaluation of the significance of exposure estimates is problematic. However, the general exposure estimation procedure developed herein for birds and mammals is applicable to reptiles and amphibians. Exposure models must be appropriate to the

  3. CONSEXPO 3.0, consumer exposure and uptake models

    NARCIS (Netherlands)

    Veen MP van; LBM

    2001-01-01

    The report provides a modelling approach to consumer exposure to chemicals, based on mathematical contact, exposure and uptake models. For each route of exposure, a number of exposure and uptake models are included. A general framework joins the exposure and uptake models selected by the user. By

  4. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure

    International Nuclear Information System (INIS)

    Hinwood, A.L.; Stasinska, A.; Callan, A.C.; Heyworth, J.; Ramalingam, M.; Boyce, M.; McCafferty, P.; Odland, J.Ø.

    2015-01-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children. - This study has demonstrated exposure to alkali, alkali earth and transition metals in pregnant women with factors such as breastfeeding, fish oil use and diet affecting exposures

  5. Development of a spatial stochastic multimedia exposure model to assess population exposure at a regional scale.

    Science.gov (United States)

    Caudeville, Julien; Bonnard, Roseline; Boudet, Céline; Denys, Sébastien; Govaert, Gérard; Cicolella, André

    2012-08-15

    Analyzing the relationship between the environment and health has become a major focus of public health efforts in France, as evidenced by the national action plans for health and the environment. These plans have identified the following two priorities: - identify and manage geographic areas where hotspot exposures are a potential risk to human health; and - reduce exposure inequalities. The aim of this study is to develop a spatial stochastic multimedia exposure model for detecting vulnerable populations and analyzing exposure determinants at a fine resolution and regional scale. A multimedia exposure model was developed by INERIS to assess the transfer of substances from the environment to humans through inhalation and ingestion pathways. The RESPIR project adds a spatial dimension by linking GIS (Geographic Information System) to the model. Tools are developed using modeling, spatial analysis and geostatistic methods to build and discretize interesting variables and indicators from different supports and resolutions on a 1-km(2) regular grid. We applied this model to the risk assessment of exposure to metals (cadmium, lead and nickel) using data from a region in France (Nord-Pas-de-Calais). The considered exposure pathways include the atmospheric contaminant inhalation and ingestion of soil, vegetation, meat, egg, milk, fish and drinking water. Exposure scenarios are defined for different reference groups (age, dietary properties, and the fraction of food produced locally). The two largest risks correspond to an ancient industrial site (Metaleurop) and the Lille agglomeration. In these areas, cadmium, vegetation ingestion and soil contamination are the principal determinants of the computed risk. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. A statistical framework for the validation of a population exposure model based on personal exposure data

    Science.gov (United States)

    Rodriguez, Delphy; Valari, Myrto; Markakis, Konstantinos; Payan, Sébastien

    2016-04-01

    Currently, ambient pollutant concentrations at monitoring sites are routinely measured by local networks, such as AIRPARIF in Paris, France. Pollutant concentration fields are also simulated with regional-scale chemistry transport models such as CHIMERE (http://www.lmd.polytechnique.fr/chimere) under air-quality forecasting platforms (e.g. Prev'Air http://www.prevair.org) or research projects. These data may be combined with more or less sophisticated techniques to provide a fairly good representation of pollutant concentration spatial gradients over urban areas. Here we focus on human exposure to atmospheric contaminants. Based on census data on population dynamics and demographics, modeled outdoor concentrations and infiltration of outdoor air-pollution indoors we have developed a population exposure model for ozone and PM2.5. A critical challenge in the field of population exposure modeling is model validation since personal exposure data are expensive and therefore, rare. However, recent research has made low cost mobile sensors fairly common and therefore personal exposure data should become more and more accessible. In view of planned cohort field-campaigns where such data will be available over the Paris region, we propose in the present study a statistical framework that makes the comparison between modeled and measured exposures meaningful. Our ultimate goal is to evaluate the exposure model by comparing modeled exposures to monitor data. The scientific question we address here is how to downscale modeled data that are estimated on the county population scale at the individual scale which is appropriate to the available measurements. To assess this question we developed a Bayesian hierarchical framework that assimilates actual individual data into population statistics and updates the probability estimate.

  7. [Occupational exposure to nanoparticles. Assessment of workplace exposure].

    Science.gov (United States)

    Bujak-Pietrek, Stella

    2010-01-01

    Nanotechnology is currently one of the most popular branch of science. It is a technology that enables designing, manufacturing and application of materials and structures of very small dimensions, and its products are applied in almost every field of life. Nanoparticles are the structures having one or more dimensions of the order of 100 nm or less. They are used in precise mechanics, electronics, optics, medicine, pharmacy, cosmetics and many other spheres. Due to their very small size, nanostructures have completely different and specific properties, unknown for the bulk of materials. Fast-growing nanotechnology provides a wide spectrum of applications, but it also brings about new and unknown danger to human health. Nanotechnology is the branch that has developed rather recently, and much information about health risk and its influence on the environment is beyond our knowledge. Nanoparticles, released in many technological processes, as well as manufactured nanoparticles can induce occupational hazards to workers. The lack of regulations and standards, compulsory in the manufacture and use ofnanoparticles is a fundamental problem faced in the evaluation of exposure. Another problem is the choice of proper measurement equipment for surveying of very small particles - their number, mass and surface area in the workpost air. In this article, the possibility and scope of exposure assessment is discussed and a brief specification of available instrumentation for counting and assessing the parameters essential for classifying the exposure to nanoparticles is presented.

  8. Quantifying human exposure to air pollution - moving from static monitoring to spatio-temporally resolved personal exposure assessment

    DEFF Research Database (Denmark)

    Steinle, Susanne; Reis, Stefan; Sabel, Clive E

    2013-01-01

    exposure studies to accurately assess human health risks. ? We discuss potential and shortcomings of methods and tools with a focus on how their development influences study design. ? We propose a novel conceptual model for integrated health impact assessment of human exposure to air pollutants. ? We......Quantifying human exposure to air pollutants is a challenging task. Ambient concentrations of air pollutants at potentially harmful levels are ubiquitous in urban areas and subject to high spatial and temporal variability. At the same time, every individual has unique activity-patterns. Exposure...... results from multifaceted relationships and interactions between environmental and human systems, adding complexity to the assessment process. Traditionally, approaches to quantify human exposure have relied on pollutant concentrations from fixed air quality network sites and static population...

  9. Mere Exposure and Racial Prejudice: Exposure to Other-Race Faces Increases Liking for Strangers of That Race.

    Science.gov (United States)

    Zebrowitz, Leslie A; White, Benjamin; Wieneke, Kristin

    2008-01-01

    White participants were exposed to other-race or own-race faces to test the generalized mere exposure hypothesis in the domain of face perception, namely that exposure to a set of faces yields increased liking for similar faces that have never been seen. In Experiment 1, rapid supraliminal exposures to Asian faces increased White participants' subsequent liking for a different set of Asian faces. In Experiment 2, subliminal exposures to Black faces increased White participants' subsequent liking for a different set of Black faces. The findings are consistent with prominent explanations for mere exposure effects as well as with the familiar face overgeneralization hypothesis that prejudice derives in part from negative reactions to faces that deviate from the familiar own-race prototype.

  10. Measuring water ingestion from spray exposures.

    Science.gov (United States)

    Sinclair, Martha; Roddick, Felicity; Nguyen, Thang; O'Toole, Joanne; Leder, Karin

    2016-08-01

    Characterisation of exposure levels is an essential requirement of health risk assessment; however for water exposures other than drinking, few quantitative exposure data exist. Thus, regulatory agencies must use estimates to formulate policy on treatment requirements for non-potable recycled water. We adapted the use of the swimming pool chemical cyanuric acid as a tracer of recreational water ingestion to permit detection of small water volumes inadvertently ingested from spray exposures. By using solutions of 700-1000 mg/L cyanuric acid in an experimental spray exposure scenario, we were able to quantify inadvertent water ingestion in almost 70% of participants undertaking a 10 min car wash activity using a high pressure spray device. Skin absorption was demonstrated to be negligible under the experimental conditions, and the measured ingestion volumes ranged from 0.06 to 3.79 mL. This method could be applied to a range of non-potable water use activities to generate exposure data for risk assessment processes. The availability of such empirical measurements will provide greater assurance to regulatory agencies and industry that potential health risks from exposure to non-potable water supplies are well understood and adequately managed to protect public health. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Health Effects of Chronic Arsenic Exposure

    Directory of Open Access Journals (Sweden)

    Young-Seoub Hong

    2014-09-01

    Full Text Available Arsenic is a unique element with distinct physical characteristics and toxicity whose importance in public health is well recognized. The toxicity of arsenic varies across its different forms. While the carcinogenicity of arsenic has been confirmed, the mechanisms behind the diseases occurring after acute or chronic exposure to arsenic are not well understood. Inorganic arsenic has been confirmed as a human carcinogen that can induce skin, lung, and bladder cancer. There are also reports of its significant association to liver, prostate, and bladder cancer. Recent studies have also suggested a relationship with diabetes, neurological effects, cardiac disorders, and reproductive organs, but further studies are required to confirm these associations. The majority of research to date has examined cancer incidence after a high exposure to high concentrations of arsenic. However, numerous studies have reported various health effects caused by chronic exposure to low concentrations of arsenic. An assessment of the health effects to arsenic exposure has never been performed in the South Korean population; thus, objective estimates of exposure levels are needed. Data should be collected on the biological exposure level for the total arsenic concentration, and individual arsenic concentration by species. In South Korea, we believe that biological exposure assessment should be the first step, followed by regular health effect assessments.

  12. Comparison of cytogenetic effects after occupational exposure to X-rays with those after foetal pelvimetric exposure

    International Nuclear Information System (INIS)

    Kirsch-Volders, M.; Poma, K.; Verschaeve, L.; Hens, L.; Susanne, C.; Elegem, P. van

    1978-01-01

    In utero acute low-level exposure to X-rays (300 to 350 mrads) induces a significant increase of band-loss in G-trypsin banded chromosomes of umbilical lymphocytes. Results, however, have to be confirmed by dose-effect relation studies and analysis with spectro-photometric scanning of deleted chromosomes. The same in utero exposure induces a significant dissociaton of chromosome pair 13 as revealed by centromere-centromere, angle and association tendency analysis of chromosome distribution in comparison with a control group. Occupational chronic low-level exposure to ionizing radiation does not modify significantly the amount of SCE in lymphocytes of peripheral blood. However, an analysis of centromere-centromere distances, angle values and associaton tendencies of the different chromosome combinations clearly shows an association of chromosome pair 12-16 after exposure to ionizing radiation. It is difficult to assess the exact biological importance of the observed chromosome modifications. However, referring to the already described dissociation of human acrocentric chromosomes after in vivo exposure to low levels of phenyl Hg acetate or inorganic Pb, the chromosome distribution seems not to be significantly disturbed by chronic or acute low-level exposure to ionizing radiation. (author)

  13. Variation in calculated human exposure. Comparison of calculations with seven European human exposure models

    NARCIS (Netherlands)

    Swartjes F; ECO

    2003-01-01

    Twenty scenarios, differing with respect to land use, soil type and contaminant, formed the basis for calculating human exposure from soil contaminants with the use of models contributed by seven European countries (one model per country). Here, the human exposures to children and children

  14. Outdoor ultraviolet exposure of children and adolescents

    International Nuclear Information System (INIS)

    Diffey, B.L.; Gibson, C.J.

    1996-01-01

    The weekday and weekend outdoor ultraviolet exposure of young people from primary and secondary schools in three geographically distinct regions of England was determined over a 3-month period in summer. Ultraviolet exposure was measured using personal film badges worn by each young person and time spent outdoors, in hourly intervals, assessed using exposure records. In each area a class of 9-10 year-old children from a primary school and a class of 14-15-year-old adolescents from a secondary school took part, giving a total of 180 subjects. We found that primary school children received higher outdoor ultraviolet exposure than young people in secondary schools, and geographical differences in exposure could not be accounted for solely by differences in ambient ultraviolet. There was little difference between the exposure of males and females. Children and adolescents did not behave as homogeneous groups with regard to exposure. (Author)

  15. Indoor, outdoor, and personal exposure monitoring of particulate air pollution: the Baltimore elderly epidemiology-exposure pilot study

    Science.gov (United States)

    Williams, Ron; Creason, John; Zweidinger, Roy; Watts, Randall; Sheldon, Linda; Shy, Carl

    A 17-day pilot study investigating potential PM exposures of an elderly population was conducted near Baltimore, Maryland. Collection of residential indoor, residential outdoor, and ambient monitoring data associated with the subjects living at a common retirement facility was integrated with results from a paired epidemiological pilot study. This integration was used to investigate the potential pathophysiological health effects resulting from daily changes in estimated PM exposures with results reported elsewhere. Objectives of the exposure study were to determine the feasibility of performing PM exposure assessment upon an elderly population and establishing relationships between the various exposure measures including personal monitoring. PM 2.5 was determined to be the dominant outdoor size fraction (0.83 PM 2.5/PM 10 mass ratio by dichot monitoring). Individual 24-h PM 1.5 personal exposures ranged from 12 to 58 μg m -3. Comparison of data from matched sampling dates resulted in mean daily PM 1.5 personal, PM 2.5 outdoor, and PM 1.5 indoor concentrations of 34, 17, and 17 μg m -3, respectively. Activity patterns of the study population indicated a generally sedentary population spending a mean of 96% of each day indoors. Future studies would benefit from the use of a consistent sampling methodology across a larger number of PM measurement sites relevant to the elderly subjects, as well as a larger personal PM exposure study population to more successfully collect data needed in matched epidemiological-exposure studies.

  16. Evaluation of cumulative PCB exposure estimated by a job exposure matrix versus PCB serum concentrations

    Science.gov (United States)

    Ruder, Avima M.; Succop, Paul; Waters, Martha A.

    2015-01-01

    Although polychlorinated biphenyls (PCBs) have been banned in many countries for more than three decades, exposures to PCBs continue to be of concern due to their long half-lives and carcinogenic effects. In National Institute for Occupational Safety and Health studies, we are using semiquantitative plant-specific job exposure matrices (JEMs) to estimate historical PCB exposures for workers (n=24,865) exposed to PCBs from 1938 to 1978 at three capacitor manufacturing plants. A subcohort of these workers (n=410) employed in two of these plants had serum PCB concentrations measured at up to four times between 1976 and 1989. Our objectives were to evaluate the strength of association between an individual worker’s measured serum PCB levels and the same worker’s cumulative exposure estimated through 1977 with the (1) JEM and (2) duration of employment, and to calculate the explained variance the JEM provides for serum PCB levels using (3) simple linear regression. Consistent strong and statistically significant associations were observed between the cumulative exposures estimated with the JEM and serum PCB concentrations for all years. The strength of association between duration of employment and serum PCBs was good for highly chlorinated (Aroclor 1254/HPCB) but not less chlorinated (Aroclor 1242/LPCB) PCBs. In the simple regression models, cumulative occupational exposure estimated using the JEMs explained 14–24 % of the variance of the Aroclor 1242/LPCB and 22–39 % for Aroclor 1254/HPCB serum concentrations. We regard the cumulative exposure estimated with the JEM as a better estimate of PCB body burdens than serum concentrations quantified as Aroclor 1242/LPCB and Aroclor 1254/HPCB. PMID:23475397

  17. Modelling exposure opportunities

    DEFF Research Database (Denmark)

    Sabel, Clive E.; Gatrell, Anthony C.; Löytönen, Markku

    2000-01-01

    This paper addresses the issues surrounding an individual's exposure to potential environmental risk factors, which can be implicated in the aetiology of a disease. We hope to further elucidate the 'lag' or latency period between the initial exposure to potential pathogens and the physical...... boundaries.We use kernel estimation to model space-time patterns. Raised relative risk is assessed by adopting appropriate adjustments for the underlying population at risk, with the use of controls. Significance of the results is assessed using Monte Carlo simulation, and comparisons are made with results...

  18. Exposure to radon

    International Nuclear Information System (INIS)

    1988-01-01

    Part 3 is given of the Code of Practice approved by the UK Health and Safety Commission with the consent of the Secretary of State for the purpose of providing practical guidance with respect to the provisions of the Ionising Radiations Regulations 1985. Part 3 gives specific guidance on the application of the Regulations to certain work involving exposure to isotopes of radon and their decay products. Aspects covered in the Regulations include restriction of exposure, dose limits, controlled areas, radiation protection advisers and supervisors, dosimetry and area monitoring. (U.K.)

  19. Exposure to natural radiation

    International Nuclear Information System (INIS)

    Green, B.M.R.

    1985-01-01

    A brief report is given of a seminar on the exposure to enhanced natural radiation and its regulatory implications held in 1985 at Maastricht, the Netherlands. The themes of the working sessions included sources of enhanced natural radiation, parameters influencing human exposure, measurement and survey programmes, technical countermeasures, risk and assessment studies, philosophies of dose limitations and national and international policies. (U.K.)

  20. Exposures of the elbow.

    Science.gov (United States)

    Axelrod, Terry S

    2014-11-01

    This article describes the basic bony, ligamentous, and neurologic anatomy of the structures about the elbow. The surgical exposures of the elbow joint are described, providing details of the various posterior, lateral, and medial approaches to the articular segments. Clinical applications describing the potential benefits of each surgical exposure are provided as examples. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Hexavalent chromium exposures and exposure-control technologies in American enterprise: results of a NIOSH field research study.

    Science.gov (United States)

    Blade, L M; Yencken, M Story; Wallace, M E; Catalano, J D; Khan, A; Topmiller, J L; Shulman, S A; Martinez, A; Crouch, K G; Bennett, J S

    2007-08-01

    The National Institute for Occupational Safety and Health (NIOSH) conducted 21 field surveys in selected industries to characterize workers' exposures to hexavalent chromium-containing airborne particulate and to evaluate existing technologies for controlling these exposures. Hexavalent chromium Cr(VI) is a respiratory irritant and chronic inhalation may cause lung cancer. Primary evaluation methods included collection of full work shift, personal breathing-zone (PBZ) air samples for Cr(VI), measurement of ventilation system parameters, and documentation of processes and work practices. This study emphasized evaluation of engineering exposure control measures, so PBZ exposures were measured on the outside of personal protective equipment, for example, respirators. Field surveys were conducted in two chromium electroplating facilities, including one where full-shift PBZ exposures to Cr(VI) ranged from 3.0 to 16 times the 1 micro g/m(3)NIOSH recommended exposure limit (REL) despite several engineering controls on the plating tanks. At a painting and coating facility that used Cr(VI)-containing products, full-shift exposures of painters and helpers (2.4 to 55 micro g/m(3)) exceeded the REL, but LEV effectiveness was limited. Other operations evaluated included welding in construction; metal cutting operations on chromium-containing materials in ship breaking; chromate-paint removal with abrasive blasting; atomized alloy-spray coating; foundry operations; printing; and the manufacture of refractory brick, colored glass, prefabricated concrete products, and treated wood products. NIOSH researchers concluded that, in many of the evaluated processes, Cr(VI) exposures at or below the current NIOSH REL are achievable. However, for some processes, it is unclear whether controlling exposures to this range is consistently achievable without respirator use. Some operations involving the application of coatings and finishes may be among those most difficult to control to this

  2. Surgery for subacromial impingement syndrome in relation to intensities of occupational mechanical exposures across 10-year exposure time windows.

    Science.gov (United States)

    Dalbøge, Annett; Frost, Poul; Andersen, Johan Hviid; Svendsen, Susanne Wulff

    2018-03-01

    We aimed to identify intensities of occupational mechanical exposures (force, arm elevation and repetition) that do not entail an increased risk of surgery for subacromial impingement syndrome (SIS) even after prolonged durations of exposure. Additionally, we wanted to evaluate if exposure to hand-arm vibration (HAV) is an independent risk factor. We used data from a register-based cohort study of the entire Danish working population (n=2 374 403). During follow-up (2003-2008), 14 118 first-time events of surgery for SIS occurred. For each person, we linked register-based occupational codes (1993-2007) to a general population job exposure matrix to obtain year-by-year exposure intensities on measurement scales for force, upper arm elevation >90° and repetition and expert rated intensities of exposure to HAV. For 10-year exposure time windows, we calculated the duration of exposure at specific intensities above minimal (low, medium and high). We used a logistic regression technique equivalent to discrete survival analysis adjusting for cumulative effects of other mechanical exposures. We found indications of safe exposure intensities for repetition (median angular velocity 90° >2 min/day implied an increased risk reaching ORs of 1.7 and 1.5 after 10 years at low intensities. No associations were found for HAV. We found indications of safe exposure intensities for repetition. Any intensities of force and upper arm elevation >90° above minimal implied an increased risk across 10-year exposure time windows. No independent associations were found for HAV. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  3. Radiation in complex exposure situations. Assessing health risks at low levels from concomitant exposures to radiation and chemicals

    International Nuclear Information System (INIS)

    Hornhardt, S.; Jung, T.; Burkart, W.

    2000-01-01

    Health effects from exposures to ionizing radiation are in general the result of complex multi-step reaction chains involving changes and responses on the level of molecules, cells, tissues and organisms. In environmental low dose exposure situations ionizing radiation only contributes a small fraction to the life-long attack on DNA by other exogenous and endogenous genotoxins. Nevertheless, efforts to assess and quantify deleterious effects at low exposure levels are directed mainly towards radiation as a single isolated agent, and rarely towards the concomitant presence of other natural and anthropogenic toxicants. Only these combined exposures may lead to observable health risk effects. In addition they might differ from those expected from simple addition of the individual risks due to interaction. The existing data base on combined effects is rudimentary, mainly descriptive and rarely covers exposure ranges large enough to make direct inferences to present day low dose exposure situations. Therefore, any risk assessment will have to consider the question whether combined effects, i.e. interaction between two or more agents will influence the health outcome from specific exposure situations in such a way that predictions derived from simple standard exposure situations would have to be revised. In view of the multitude of possible interactions between the large number of potentially harmful agents in the human environment, descriptive approaches will have to be supplemented by the use of mechanistic models for critical health endpoints such as cancer. Agents will have to be grouped depending on their physical or chemical mode of action at the molecular and cellular level, to generalize and predict the outcome of combined exposures at low exposure levels and the possibility of interactions. (author)

  4. Exposure to background radiation in Australia

    International Nuclear Information System (INIS)

    Solomon, S.B.

    1997-01-01

    The average effective dose received by the Australian population is estimated to be ∼1.8 mSv / year. One half of this exposure arises from exposure from terrestrial radiation and cosmic rays, the remainder from radionuclides within the body and from inhalation of radon progeny. This paper reviews a number of research programmes carried out by the Australian Radiation Laboratory to study radiation exposure from natural background, particularly in the workplace and illustrate approaches to the quantification and management of exposure to natural radiation. The average radiation doses to the Australian population are relatively low; the average annual radon concentration ranged from 6 Bq m -3 in Queensland to 16 Bq m -3 in the Australian Capital Territory (ACT). Of more importance is the emerging issue of exposure to elevated background radiation in the workplace. Two situation are presented; the radiation exposure to air crues and show cave tour guides. Annual doses up to 3.8 mSv were estimated for international crew members while the highest estimate for show cave tour guides was 9 mSv per year

  5. Occupational exposure to beryllium in French enterprises: a survey of airborne exposure and surface levels.

    Science.gov (United States)

    Vincent, Raymond; Catani, Jacques; Créau, Yvon; Frocaut, Anne-Marie; Good, Andrée; Goutet, Pierre; Hou, Alain; Leray, Fabrice; André-Lesage, Marie-Ange; Soyez, Alain

    2009-06-01

    An assessment survey of occupational exposure to beryllium (Be) was conducted in France between late 2004 and the end of 2006. Exposure estimates were based on the analytical results of samples collected from workplace air and from work surfaces in 95 facilities belonging to 37 sectors of activity. The results of this study indicated airborne Be concentrations in excess of the occupational exposure limit value of 2 microg m(-3) recommended in France. Metallurgy and electronic component manufacturing represented the activities and occupations where workers had the highest arithmetic mean exposures to Be. Surface contamination levels were also high and frequently exceeded thresholds recommended by different bodies. These results should prompt the development of prevention programmes that include Be substitution, process control and surface decontamination, in conjunction with suitable medical surveillance.

  6. Challenges and Perspectives of Nanoparticle Exposure Assessment

    OpenAIRE

    Lee, Ji Hyun; Moon, Min Chaul; Lee, Joon Yeob; Yu, Il Je

    2010-01-01

    Nanoparticle exposure assessment presents a unique challenge in the field of occupational and environmental health. With the commercialization of nanotechnology, exposure usually starts from the workplace and then spreads to environment and consumer exposure. This report discusses the current trends of nanoparticle exposure assessment, including the definition of nanotechnology relevant terms, essential physicochemical properties for nanomaterial characterization, current international activi...

  7. Environmental radiation and exposure to radiation

    International Nuclear Information System (INIS)

    1981-02-01

    Compared to 1977 the exposure to radiation of the population of the Federal Republic of Germany from both natural and artificial radiation sources has not greatly charged. The amin part of exposure to natural radiation is caused by environmental radiation and by the absorption of naturally radioactive substances into the body. Artificial exposure to radiation of the population is essentially caused by the use of ionizing rays and radioactive substances in medicine. When radioactive materials are released from nuclear facilities the exposure to radiation of the population is only very slightly increased. The real exposure to radiation of individual people can even in the worst affected places, have been at most fractions of a millirem. The exposure to radiation in the worst afected places in the area of a hard-coal power station is higher than that coming from a nuclear power station of the same capacity. The summation of all contributions to the exposure of radiation by nuclear facilities to the population led in 1978 in the Federal Republic of Germany to a genetically significant dose of clearly less than 1 millerem per year. The medium-ranged exposure to radiation by external radiation effects through professional work was in 1978 at 80 millirems. No difference to 1977. The contribution of radionuclide from the fallout coming from nuclear-weapon tests and which has been deposited in the soil, to the whole-body dose for 1978 applies the same as the genetically significant dose of the population with less than 1 millirem. (orig./HP) [de

  8. Time-activity relationships to VOC personal exposure factors

    Science.gov (United States)

    Edwards, Rufus D.; Schweizer, Christian; Llacqua, Vito; Lai, Hak Kan; Jantunen, Matti; Bayer-Oglesby, Lucy; Künzli, Nino

    Social and demographic factors have been found to play a significant role in differences between time-activity patterns of population subgroups. Since time-activity patterns largely influence personal exposure to compounds as individuals move across microenvironments, exposure subgroups within the population may be defined by factors that influence daily activity patterns. Socio-demographic and environmental factors that define time-activity subgroups also define quantifiable differences in VOC personal exposures to different sources and individual compounds in the Expolis study. Significant differences in exposures to traffic-related compounds ethylbenzene, m- and p-xylene and o-xylene were observed in relation to gender, number of children and living alone. Categorization of exposures further indicated time exposed to traffic at work and time in a car as important determinants. Increased exposures to decane, nonane and undecane were observed for males, housewives and self-employed. Categorization of exposures indicated exposure subgroups related to workshop use and living downtown. Higher exposures to 3-carene and α-pinene commonly found in household cleaning products and fragrances were associated with more children, while exposures to traffic compounds ethylbenzene, m- and p-xylene and o-xylene were reduced with more children. Considerable unexplained variation remained in categorization of exposures associated with home product use and fragrances, due to individual behavior and product choice. More targeted data collection methods in VOC exposure studies for these sources should be used. Living alone was associated with decreased exposures to 2-methyl-1-propanol and 1-butanol, and traffic-related compounds. Identification of these subgroups may help to reduce the large amount of unexplained variation in VOC exposure studies. Further they may help in assessing impacts of urban planning that result in changes in behavior of individuals, resulting in shifts in

  9. DOE 2010 occupational radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2011-11-01

    The U.S. Department of Energy (DOE) Office of Analysis within the Office of Health, Safety and Security (HSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE.* The DOE 2010 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with DOE Part 835 dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protection of individuals from the effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. The occupational radiation exposure information is analyzed in terms of aggregate data, dose to individuals, and dose by site over the past 5 years.

  10. Bases for establishing radiation exposure limits

    International Nuclear Information System (INIS)

    Pochin, E.E.

    1977-01-01

    It is an essential requirement of good radiation protection that all unnecessary exposure of people should be avoided and that any necessary exposure, whether of workers or of members of the general public, should be minimised. It is, however, an additional requirement that such necessary exposures should not exceed certain stated limits. These principles are based on the possibility that even the smallest exposures may involve some risk of harm, that any risk of harm should be justifiable by the circumstances necessitating it, and that risk should always be limited to an appropriately low level. The bases for establishing exposure limits must therefore involve an assessment of the risk involved in any form of radiation exposure, and an opinion as to the degree of safety that should be ensured in circumstances which necessitate any occupational or public exposure to radiation. There is increasing quantitative evidence on the frequency on which harm, and particularly the induction of malignancies, may be caused in people exposed to radiation at high doses; and somewhat clearer bases than previously for inferring the possible frequencies at low doses. It is therefore easier to assess the degree of safety ensured by restricting radiation exposure to particular levels. The degree of safety which should be regarded as appropriate in different circumstances remains a matter for review, but suggestions are made as to levels which would be advocated by informed opinion, and the exposure limits which would correspond to these. It is clear also that a comparable degree of safety should be ensured whether the radiation exposure involves the whole body more of less uniformly, or individual tissues or organs selectively. Increasing epidemiological evidence is available on the relative sensitivity to radiation induction of malignancies in a number of organs, and to the apparently much lower sensitivity of other organs; and experimental evidence in animals allows a comparable

  11. Open-field exposure facilitates consummatory extinction.

    Science.gov (United States)

    Justel, Nadia; Psyrdellis, Mariana; Pautassi, Ricardo M

    2016-12-07

    During extinction, the organism learns that a conditioned stimulus or a conditioned response is no longer associated with an unconditioned stimulus, and as a consequence, a decrement in the response is presented. The exposure to novel situations (e.g. exploration of a novel open field) has been used widely to modulate (i.e. either enhance or deteriorate) learning and memory. The aim of the present study was to test whether open-field exposure could modulate consummatory extinction. The results indicated that open-field exposure accelerated the extinction response (i.e. experimental animals provided novelty exposure had lower consummatory behavior than control animals) when applied before - but not after - the first extinction trial, or when applied before the second extinction trial. The results suggest that environmental treatments such as novelty exposure provide a valuable, nonpharmacological alternative to potentially modulate extinction processes.

  12. External radiation exposure of the public

    International Nuclear Information System (INIS)

    Mehl, J.

    1977-01-01

    Results of several ten thousand measurements on external radiation (outside buildings, in living rooms) are used for illustrating by isodose charts covering the total area of the Federal Republic of Germany the exposure of the public from external radiation originating from natural radiation of the environment. Results of calculations on external radiation exposure of the public due to releases of radioactivity in air from nuclear installations are used for illustrating by coloured isodose charts the exposure of the public in the plant site vicinity. From comparison of the exposure levels it becomes obvious that if exposure levels of several 10 mrem per year are considered to be of real concern to public health, control of natural radoactivity in the environment of man would require more attention than present and foreseeable releases of radioactivity in air from nuclear inst

  13. Cost benefit analysis for occupational radiation exposure

    International Nuclear Information System (INIS)

    Caruthers, G.F.; Rodgers, R.C.; Donohue, J.P.; Swartz, H.M.

    1978-01-01

    In the course of system design, many decisions must be made concerning different aspects of that particular system. The design of systems and components in a nuclear power plant has the added faction of occupational exposure experienced as a result of that design. This paper will deal with the different methods available to factor occupational exposure into design decisions. The ultimate goal is to have exposures related to the design 'As Low As Reasonably Achievable' or ALARA. To do this an analysis should be performed to show that the cost of reducing exposures any further cannot be justified in a cost-benefit analysis. In this paper examples will be given that will show that it is possible to change to a design which would increase occupational exposure somewhat but would increase the benefit over the cost of the extra exposure received. It will also be shown that some changes in design or additional equipment could be justified due to a reduction in exposure while some changes could not be justified on a reduction in exposure aspect alone but are justified on a time saving aspect such as during a refueling outage. (author)

  14. Prevalence of hazardous exposures in veterinary practice

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, P.; Schenker, M.B.; Green, R.; Samuels, S.

    1989-01-01

    All female graduates of a major U.S. veterinary school were surveyed by mailed questionnaire to obtain details of work practice and hazard exposure during the most recent year worked and during all pregnancies. Exposure questions were based on previously implicated occupational hazards which included anesthetic gases, radiation, zoonoses, prostaglandins, vaccines, physical trauma, and pesticides. The response rate was 86% (462/537). We found that practice type and pregnancy status were major determinants of hazard exposure within the veterinary profession. Small-animal practitioners reported the highest rates of exposure to anesthetic gas (94%), X-ray (90%), and pesticides (57%). Large-animal practitioners reported greater rates of trauma (64%) and potential exposure to prostaglandins (92%), Brucella abortus vaccine (23%), and carbon monoxide (18%). Potentially hazardous workplace practices or equipment were common. Forty-one percent of respondents who reported taking X-rays did not wear film badges, and 76% reported physically restraining animals for X-ray procedures. Twenty-seven percent of the respondents exposed to anesthetic gases worked at facilities which did not have waste anesthetic gas scavenging systems. Women who worked as veterinarians during a pregnancy attempted to reduce exposures to X-rays, insecticides, and other potentially hazardous exposures. Some potentially hazardous workplace exposures are common in veterinary practice, and measures to educate workers and to reduce these exposures should not await demonstration of adverse health effects.

  15. Prevalence of hazardous exposures in veterinary practice

    International Nuclear Information System (INIS)

    Wiggins, P.; Schenker, M.B.; Green, R.; Samuels, S.

    1989-01-01

    All female graduates of a major U.S. veterinary school were surveyed by mailed questionnaire to obtain details of work practice and hazard exposure during the most recent year worked and during all pregnancies. Exposure questions were based on previously implicated occupational hazards which included anesthetic gases, radiation, zoonoses, prostaglandins, vaccines, physical trauma, and pesticides. The response rate was 86% (462/537). We found that practice type and pregnancy status were major determinants of hazard exposure within the veterinary profession. Small-animal practitioners reported the highest rates of exposure to anesthetic gas (94%), X-ray (90%), and pesticides (57%). Large-animal practitioners reported greater rates of trauma (64%) and potential exposure to prostaglandins (92%), Brucella abortus vaccine (23%), and carbon monoxide (18%). Potentially hazardous workplace practices or equipment were common. Forty-one percent of respondents who reported taking X-rays did not wear film badges, and 76% reported physically restraining animals for X-ray procedures. Twenty-seven percent of the respondents exposed to anesthetic gases worked at facilities which did not have waste anesthetic gas scavenging systems. Women who worked as veterinarians during a pregnancy attempted to reduce exposures to X-rays, insecticides, and other potentially hazardous exposures. Some potentially hazardous workplace exposures are common in veterinary practice, and measures to educate workers and to reduce these exposures should not await demonstration of adverse health effects

  16. Understanding the Impact of Exposure Patterns on Risks from Combined Exposures to Multiple Chemicals

    Science.gov (United States)

    The talk was invited so there is no formal abstract. However, the focus of the talk is on the use of exposure information in the evaluation of risks from combined exposures to chemicals. The talk presents a bit of history and several case studies. All empirical data presented hav...

  17. Infant media exposure and toddler development.

    Science.gov (United States)

    Tomopoulos, Suzy; Dreyer, Benard P; Berkule, Samantha; Fierman, Arthur H; Brockmeyer, Carolyn; Mendelsohn, Alan L

    2010-12-01

    To determine whether duration and content of media exposure in 6-month-old infants are associated with development at age 14 months. Longitudinal analysis of 259 mother-infant dyads participating in a long-term study related to early child development, from November 23, 2005, through January 14, 2008. An urban public hospital. Mothers with low socioeconomic status and their infants. Duration and content of media exposure at age 6 months. Cognitive and language development at age 14 months. Of 259 infants, 249 (96.1%) were exposed to media at age 6 months, with mean (SD) total exposure of 152.7 (124.5) min/d. In unadjusted and adjusted analyses, duration of media exposure at age 6 months was associated with lower cognitive development at age 14 months (unadjusted: r = -0.17, P development (r = -0.16, P cognitive and language development at age 14 months. No significant associations were seen with exposure to young child-oriented educational or noneducational content. This study is the first, to our knowledge, to have longitudinally assessed associations between media exposure in infancy and subsequent developmental outcomes in children from families with low socioeconomic status in the United States. Findings provide strong evidence in support of the American Academy of Pediatrics recommendations of no media exposure prior to age 2 years, although further research is needed.

  18. Review of Phthalates Exposure and Toxicity

    Directory of Open Access Journals (Sweden)

    Samaneh Taghilou

    2015-12-01

    Full Text Available The dialkyl- or alkyl/aryl esters of 1, 2-benzenedicarboxylic acid, which are known as Phthalates, are high-production volume synthetic chemicals and considered as environmental pollutants, due to high production and uses in community, plastics industry and common consuming products. Di-(2-ethylhexyl phthalate (DEHP is the most abundant phthalate in the environment. Human exposure with DEHP could be done via different chemical compounds including food packaging, household furnishings, nutritional supplements, cleaning materials and insecticides. Besides, exposure of human with phthalates occurs through different pathways such as direct contact and using Phthalate-containing products, and indirectly through leaching into other products, or general environmental contaminations. Historically, the diet has been considered the major source of phthalate exposure in the general population, but in all sources, pathways, and their relative contributions to human exposures are not well understood. Medical devices are other source of significant exposure in human. Furthermore, cosmetics, personal care products, pharmaceuticals, nutritional supplements, herbal remedies and insecticides, may result in significant but poorly quantified human exposure with this compounds. In the present review article, we tried to discuss about metabolism of phthalates in human, toxicity, monitoring of phthalates in foods, environment, and cosmetic products and then metabolites of phthalates. Finally, evaluation of human exposure through biological control is discussed.

  19. Doses from radiation exposure

    International Nuclear Information System (INIS)

    Menzel, H-G.; Harrison, J.D.

    2012-01-01

    Practical implementation of the International Commission on Radiological Protection’s (ICRP) system of protection requires the availability of appropriate methods and data. The work of Committee 2 is concerned with the development of reference data and methods for the assessment of internal and external radiation exposure of workers and members of the public. This involves the development of reference biokinetic and dosimetric models, reference anatomical models of the human body, and reference anatomical and physiological data. Following ICRP’s 2007 Recommendations, Committee 2 has focused on the provision of new reference dose coefficients for external and internal exposure. As well as specifying changes to the radiation and tissue weighting factors used in the calculation of protection quantities, the 2007 Recommendations introduced the use of reference anatomical phantoms based on medical imaging data, requiring explicit sex averaging of male and female organ-equivalent doses in the calculation of effective dose. In preparation for the calculation of new dose coefficients, Committee 2 and its task groups have provided updated nuclear decay data (ICRP Publication 107) and adult reference computational phantoms (ICRP Publication 110). New dose coefficients for external exposures of workers are complete (ICRP Publication 116), and work is in progress on a series of reports on internal dose coefficients to workers from inhaled and ingested radionuclides. Reference phantoms for children will also be provided and used in the calculation of dose coefficients for public exposures. Committee 2 also has task groups on exposures to radiation in space and on the use of effective dose.

  20. Fluoroscopic radiation exposure: are we protecting ourselves adequately?

    Science.gov (United States)

    Hoffler, C Edward; Ilyas, Asif M

    2015-05-06

    While traditional intraoperative fluoroscopy protection relies on thyroid shields and aprons, recent data suggest that the surgeon's eyes and hands receive more exposure than previously appreciated. Using a distal radial fracture surgery model, we examined (1) radiation exposure to the eyes, thyroid, chest, groin, and hands of a surgeon mannequin; (2) the degree to which shielding equipment can decrease exposure; and (3) how exposure varies with fluoroscopy unit size. An anthropomorphic model was fit with radiation-attenuating glasses, a thyroid shield, an apron, and gloves. "Exposed" thermoluminescent dosimeters overlaid the protective equipment at the eyes, thyroid, chest, groin, and index finger while "shielded" dosimeters were placed beneath the protective equipment. Fluoroscopy position and settings were standardized. The mini-c-arm milliampere-seconds were fixed based on the selection of the kilovolt peak (kVp). Three mini and three standard c-arms scanned a model of the patient's wrist continuously for fifteen minutes each. Ten dosimeter exposures were recorded for each c-arm. Hand exposure averaged 31 μSv/min (range, 22 to 48 μSv/min), which was 13.0 times higher than the other recorded exposures. Eye exposure averaged 4 μSv/min, 2.2 times higher than the mean thyroid, chest, and groin exposure. Gloves reduced hand exposure by 69.4%. Glasses decreased eye exposure by 65.6%. There was no significant difference in exposure between mini and standard fluoroscopy. Surgeons' hands receive the most radiation exposure during distal radial plate fixation under fluoroscopy. There was a small but insignificant difference in mean exposure between standard fluoroscopy and mini-fluoroscopy, but some standard units resulted in lower exposure than some mini-units. On the basis of these findings, we recommend routine protective equipment to mitigate exposure to surgeons' hands and eyes, in addition to the thyroid, chest, and groin, during fluoroscopy procedures

  1. Radiation protection: occupational exposure

    International Nuclear Information System (INIS)

    Shah, G.A.

    1990-01-01

    The basis of the occupational exposure limit of 50 mSv recommended by the ICRP is questioned. New dosimetry at Hiroshima and Nagasaki, the fact that the dose-response curve may be non-linear and that the relative risk model may be applicable, are some of the arguments advanced to support a reduction in the occupational exposure dose limits. 5 refs., 2 tabs., 3 figs

  2. Air Pollution Exposure Modeling for Health Studies | Science ...

    Science.gov (United States)

    Dr. Michael Breen is leading the development of air pollution exposure models, integrated with novel personal sensor technologies, to improve exposure and risk assessments for individuals in health studies. He is co-investigator for multiple health studies assessing the exposure and effects of air pollutants. These health studies include participants with asthma, diabetes, and coronary artery disease living in various U.S. cities. He has developed, evaluated, and applied novel exposure modeling and time-activity tools, which includes the Exposure Model for Individuals (EMI), GPS-based Microenvironment Tracker (MicroTrac) and Exposure Tracker models. At this seminar, Dr. Breen will present the development and application of these models to predict individual-level personal exposures to particulate matter (PM) for two health studies in central North Carolina. These health studies examine the association between PM and adverse health outcomes for susceptible individuals. During Dr. Breen’s visit, he will also have the opportunity to establish additional collaborations with researchers at Harvard University that may benefit from the use of exposure models for cohort health studies. These research projects that link air pollution exposure with adverse health outcomes benefit EPA by developing model-predicted exposure-dose metrics for individuals in health studies to improve the understanding of exposure-response behavior of air pollutants, and to reduce participant

  3. Foreign exchange transaction exposure of enterprises in Serbia

    Directory of Open Access Journals (Sweden)

    Bogićević Jasmina

    2016-01-01

    Full Text Available Enterprises involved in international business face transaction exposure to foreign exchange risk. This type of exposure occurs when an enterprise trades, borrows, or lеnds in foreign currency. Transaction exposure has a direct effect on an enterprise’s financial position and profitability. It is one of the three forms of exposure to exchange rate fluctuations, the other two being translation exposure and operating exposure. The aim of this paper is to assess the transaction exposure of enterprises in Serbia operating internationally. In addition to identifying and measuring transaction exposure, this paper explores the practical importance that enterprises in Serbia attach to management of this type of foreign exchange risk. We do not find significant differences between domestic and foreign enterprises in their choice of the type of foreign exchange risk exposure to manage. Although transaction exposure is the most managed type of foreign exchange risk, research has shown that, compared to foreign businesses, Serbian enterprises do not use sufficient protective measures to minimize the negative impact of this type of exposure on their cash flows and profitability. We expected that there would be a statistically significant dependence between the volume of enterprises’ foreign currency transactions and the level of applied transaction exposure management practices. However, the results of our research, based on a sample of enterprises in Serbia operating internationally, show that transaction exposure management practices can be influenced by factors other than the level of an enterprise’s foreign currency transactions, such as the enterprise’s country of origin.

  4. Environmental exposure assessment in European birth cohorts

    DEFF Research Database (Denmark)

    Gehring, Ulrike; Casas, Maribel; Brunekreef, Bert

    2013-01-01

    of the environmental exposure and health data in these studies was made as part of the ENRIECO (Environmental Health Risks in European Birth Cohorts) project. The focus with regard to exposure was on outdoor air pollution, water contamination, allergens and biological organisms, metals, pesticides, smoking and second...... hand tobacco smoke (SHS), persistent organic pollutants (POPs), noise, radiation, and occupational exposures. The review lists methods and data on environmental exposures in 37 European birth cohort studies. Most data is currently available for smoking and SHS (N=37 cohorts), occupational exposures (N......Environmental exposures during pregnancy and early life may have adverse health effects. Single birth cohort studies often lack statistical power to tease out such effects reliably. To improve the use of existing data and to facilitate collaboration among these studies, an inventory...

  5. Lead exposure in US worksites: A literature review and development of an occupational lead exposure database from the published literature

    Science.gov (United States)

    Koh, Dong-Hee; Locke, Sarah J.; Chen, Yu-Cheng; Purdue, Mark P.; Friesen, Melissa C.

    2016-01-01

    Background Retrospective exposure assessment of occupational lead exposure in population-based studies requires historical exposure information from many occupations and industries. Methods We reviewed published US exposure monitoring studies to identify lead exposure measurement data. We developed an occupational lead exposure database from the 175 identified papers containing 1,111 sets of lead concentration summary statistics (21% area air, 47% personal air, 32% blood). We also extracted ancillary exposure-related information, including job, industry, task/location, year collected, sampling strategy, control measures in place, and sampling and analytical methods. Results Measurements were published between 1940 and 2010 and represented 27 2-digit standardized industry classification codes. The majority of the measurements were related to lead-based paint work, joining or cutting metal using heat, primary and secondary metal manufacturing, and lead acid battery manufacturing. Conclusions This database can be used in future statistical analyses to characterize differences in lead exposure across time, jobs, and industries. PMID:25968240

  6. Exposure to organophosphate flame retardants in spray polyurethane foam applicators: Role of dermal exposure.

    Science.gov (United States)

    Bello, Anila; Carignan, Courtney C; Xue, Yalong; Stapleton, Heather M; Bello, Dhimiter

    2018-04-01

    Spray polyurethane foam (SPF) is a highly effective thermal insulation material that has seen considerable market growth in the past decade. Organophosphate flame retardants (PFRs) are added to SPF formulations to meet fire code requirements. A common flame retardant used in SPF formulations is tris 1-chloro 2-propyl phosphate (TCIPP), a suspected endocrine disruptor. Exposure monitoring efforts during SPF applications have focused primarily on the isocyanate component, a potent respiratory and dermal sensitizer. However, to our knowledge, there is no monitoring data for TCIPP. To characterize occupational exposures to TCIPP and other flame retardants during SPF insulation. Workers at four SPF insulation sites and one foam removal site (total n = 14) were recruited as part of this pilot study. Personal inhalation exposure to TCIPP was monitored with a CIP-10MI inhalable sampler and potential dermal exposure was assessed through the use of a glove dosimeter. Biomarkers of TCIPP and three other PFRs were measured in urine collected from workers pre-and post-shift. Linear mixed effect models were used to analyze associations of urinary biomarkers with inhalation and dermal exposures and paired t-tests were used to examine the difference on the means of urinary biomarkers pre-and post-shift. Chemical analysis of all species was performed with liquid chromatography-electrospray ionization tandem mass spectrometry. Geometric mean (GM) concentrations of TCIPP in personal air monitors and glove dosimeters collected from SPF applicators, 294.7 μg/m 3 and 18.8 mg/pair respectively. Overall, GM concentrations of the two TCIPP urinary biomarkers BCIPP and BCIPHIPP and (6.2 and 88.8 μg/mL) were 26-35 times higher than reported in the general population. Post-shift levels of TCIPP biomarkers were higher than pre-shift even though workers at insulation sites wore supplied air respirators, gloves and coveralls. The urinary biomarkers for the other PFRs were not

  7. Noise exposure and public health

    NARCIS (Netherlands)

    Passchier-Vermeer, W.; Passchier, W.F.

    2000-01-01

    Exposure to noise constitutes a health risk. There is sufficient scientific evidence that noise exposure can induce hearing impairment, hypertension and ischemic heart disease, annoyance, sleep disturbance, and decreased school performance. For other effects such as changes in the immune system and

  8. Diesel Exhaust Exposure, Wheezing and Sneezing

    Science.gov (United States)

    2012-01-01

    The rising incidence of allergic disorders in developed countries is unexplained. Exposure to traffic related air pollutants may be an important cause of wheezing and asthma in childhood. Experimental evidence from human studies suggests that diesel exhaust particles, constituents of fine particulate matter less than 2.5 microns (PM2.5), may act to enhance IgE mediated aeroallergen sensitization and Th2 directed cytokine responses. To date, epidemiologic investigations indicate that children living in close proximity to heavily travelled roads are more likely to be atopic and wheeze. The Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) birth cohort study was initiated to test the hypothesis that early high exposure to traffic related air pollutants is associated with early aeroallergen sensitization and allergic respiratory phenotypes. Using an exposure cohort design, more than 700 infants born to atopic parents were recruited at age 1 living either less than 400 meters (high traffic pollutant exposure) or greater than 1,500 meters (low exposure) from a major road. Children were medically evaluated and underwent skin prick testing with aeroallergen at screening, and re-evaluated sequentially at ages 1, 2, 3, 4, and 7. In this study, both proximity and land use regression (LUR) models of traffic air pollutant exposure have been assessed. Proximity to stop and go traffic with large concentrations of bus and truck traffic predicted persistent wheezing during infancy. The LUR model estimated elemental carbon attributable to traffic (ECAT) as a proxy for diesel exhaust particulate exposure. High ECAT was significantly associated with wheezing at age 1 as well as persistent wheezing at age 3. High mold exposure predicted a well defined asthma phenotype at age 7. PMID:22754710

  9. When is exposure to a natural disaster traumatic? Comparison of a trauma questionnaire and disaster exposure inventory.

    Science.gov (United States)

    Harville, Emily W; Jacobs, Marni; Boynton-Jarrett, Renée

    2015-01-01

    Few studies have compared the sensitivity of trauma questionnaires to disaster inventories for assessing the prevalence of exposure to natural disaster or associated risk for post-disaster psychopathology. The objective of this analysis was to compare reporting of disaster exposure on a trauma questionnaire (Brief Trauma Questionnaire [BTQ]) to an inventory of disaster experience. Between 2011 and 2014, a sample of 841 reproductive-aged southern Louisiana women were interviewed using the BTQ and completed a detailed inventory about exposure to hurricanes and flooding. Post-traumatic stress disorder (PTSD) symptomology was measured with the Post-Traumatic Stress Checklist, and depression with the Edinburgh Depression Scale. The single question addressing disaster exposure on the BTQ had a sensitivity of between 65% and 70% relative to the more detailed questions. Reporting disaster exposure on the BTQ was more likely for those who reported illness/injury due to a hurricane or flood (74%-77%) or danger (77-79%), compared to those who reported damage (69-71%) or evacuation (64-68%). Reporting disaster exposure on the BTQ was associated with depression (odds ratio [OR] 2.29, 95% confidence interval [CI] 1.43-3.68). A single question is unlikely to be useful for assessing the degree of exposure to disaster across a broad population, and varies in utility depending on the mental health outcome of interest: the single trauma question is useful for assessing depression risk.

  10. Computing transient exposure to indoor pollutants

    International Nuclear Information System (INIS)

    Owczarski, P.C.; Parker, G.B.

    1983-03-01

    A computer code, CORRAL, is used to compute the transient levels of gases and respirable particulates in a residence. Predictions of time-varying exposure to radon (from the outside air, soil and well water) and respirable particulates (from outside air, wood stove operation and cigarette smoke) for a mother and child over 24 hours are made. Average 24-hour radon exposures are 13 times background (0.75 pCi/l) for the child and 4.5 times background for the mother. Average 24-hour respirable particulate exposures are 5.6 times background (100 μg/m 3 ) for the mother and 4.2 times background for the child. The controlling parameters examined are source location, flow rates between rooms, air infiltration rate and lifestyle. The first three are shown to influence the formation of local pockets of high concentration of radon and particulates, and the last parameter shows that lifestyle patterns ultimately govern individual exposure to these pockets of high concentrations. The code is useful for examination of mitigation measures to reduce exposure and examination of the effects that the controlling parameters have on exposure to indoor pollutants

  11. Adverse effects of e-cigarette exposures.

    Science.gov (United States)

    Cantrell, F Lee

    2014-06-01

    In 2007, a new source of nicotine exposure was introduced to the United States market, the electronic cigarette (ECIG) or "e-cigarette". Since then, the USA ECIG market has been doubling annually. Despite their widespread popularity, there is a paucity of existing data regarding ECIG toxicity. We report the experience of a statewide poison system. The database of a statewide poison system was queried for human ECIG exposures from 2010 (when Poisindex code first generated) through 2012. Year, age, manner and route of exposure, estimate exposure amount, product concentration, if evaluated at healthcare facility and symptoms were recorded. A total of 35 cases were identified--4 in 2010, 12 in 2011, 19 in 2012. Age range 8 months-60 years. Reported symptoms were mild and transient. Five patients were evaluated in an emergency department and none were admitted. Product concentrations ranged from 4 to 30 mg of nicotine per ml. Poison centers are likely to see an increase in exposures to ECIG given their growing popularity. Our modest results suggest that adverse effects and accidental exposures to ECIG cartridges are unlikely to result in serious toxicity.

  12. Exposure to background radiation in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, S.B. [Australian Radiation Lab., Melbourne, VIC (Australia)

    1997-12-31

    The average effective dose received by the Australian population is estimated to be {approx}1.8 mSv / year. One half of this exposure arises from exposure from terrestrial radiation and cosmic rays, the remainder from radionuclides within the body and from inhalation of radon progeny. This paper reviews a number of research programmes carried out by the Australian Radiation Laboratory to study radiation exposure from natural background, particularly in the workplace and illustrate approaches to the quantification and management of exposure to natural radiation. The average radiation doses to the Australian population are relatively low; the average annual radon concentration ranged from 6 Bq m{sup -3} in Queensland to 16 Bq m{sup -3} in the Australian Capital Territory (ACT). Of more importance is the emerging issue of exposure to elevated background radiation in the workplace. Two situation are presented; the radiation exposure to air crues and show cave tour guides. Annual doses up to 3.8 mSv were estimated for international crew members while the highest estimate for show cave tour guides was 9 mSv per year. 9 refs., 2 tabs., 4 figs.

  13. Overview of UNSCEAR re-evaluation of public exposure

    International Nuclear Information System (INIS)

    Rochedo, Elaine R.R.

    2009-01-01

    The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has re-evaluated the levels of public radiation exposure for four broad categories of sources: natural sources of radiation, enhanced exposure to naturally occurring radioactive material (NORM), man-made sources used for peaceful purposes and man-made sources used for military purposes. Regarding natural radiation sources, recent data confirmed former results from 2000 Report, but with a more wide range. Very few information is available for public exposure from NORM. Most works describes concentration levels but dose assessments are usually restricted to occupational exposures. The use of source and by-product materials may however lead to doses up to a few milisieverts to members of the public. The nuclear fuel cycle and electric energy generation have very small contributions to public exposure. Uranium mining contributes with the largest individual doses, mainly due to radon from tailings. Most relevant military use of nuclear energy were the atmospheric nuclear tests, interrupted in the 60's. Residual radioactivity deposited worldwide is now responsible for a very small contribution to worldwide exposures. However, they left a legacy of several contaminated sites. The use of depleted uranium in munitions in Kuwait, Kosovo, Serbia, Montenegro and Bosnia-Herzegovina, has led to great public concern, although not usually associated to any major consequence regarding public exposure. Some accidents resulted in environmental contamination and exposures of members of the public. Except for the Chernobyl accident, the areas affected were usually small and the exposure restricted to small number of persons, up to a few hundred, without any significant contribution to worldwide exposures. The exposure to natural sources of radiation is still the major component of worldwide exposure to ionizing radiation although for some highly developed countries, medical exposure has surpassed the

  14. Individual exposure to NO2 in relation to spatial and temporal exposure indices in Stockholm, Sweden: the INDEX study.

    Directory of Open Access Journals (Sweden)

    Tom Bellander

    Full Text Available Epidemiology studies of health effects from air pollution, as well as impact assessments, typically rely on ambient monitoring data or modelled residential levels. The relationship between these and personal exposure is not clear. To investigate personal exposure to NO(2 and its relationship with other exposure metrics and time-activity patterns in a randomly selected sample of healthy working adults (20-59 years living and working in Stockholm. Personal exposure to NO(2 was measured with diffusive samplers in sample of 247 individuals. The 7-day average personal exposure was 14.3 µg/m(3 and 12.5 µg/m(3 for the study population and the inhabitants of Stockholm County, respectively. The personal exposure was significantly lower than the urban background level (20.3 µg/m(3. In the univariate analyses the most influential determinants of individual exposure were long-term high-resolution dispersion-modelled levels of NO(2 outdoors at home and work, and concurrent NO(2 levels measured at a rural location, difference between those measured at an urban background and rural location and difference between those measured in busy street and at an urban background location, explaining 20, 16, 1, 2 and 4% (R(2 of the 7-day personal NO(2 variation, respectively. A regression model including these variables explained 38% of the variation in personal NO(2 exposure. We found a small improvement by adding time-activity variables to the latter model (R(2 = 0.44. The results adds credibility primarily to long-term epidemiology studies that utilise long-term indices of NO(2 exposure at home or work, but also indicates that such studies may still suffer from exposure misclassification and dilution of any true effects. In contrast, urban background levels of NO(2 are poorly related to individual exposure.

  15. Natural radio-exposure

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    Although the amounts are small, man is exposed on a daily basis to alpha, beta, and gamma radiation emitted by radioactive elements present in the earth's crust. The natural radioactive elements are measurable, either by physicochemical means or by radiometric methods and can be the cause of external or internal exposure in man. Also of importance is cosmic radiation. Of galactic or solar origin, primary cosmic rays cause external radiation exposure. The majority of these particles disintegrate rapidly. They reach the ground at a mean rate of the order of one particle per square centimeter per minute

  16. INFLUENCE OF EXPOSURE ASSESSMENT METHOD IN AN EPIDEMIOLOGIC STUDY OF TRIHALOMETHANE EXPOSURE AND SPONTANEOUS ABORTION

    Science.gov (United States)

    Trihalomethanes are common contaminants of chlorinated drinking water. Studies of their health effects have been hampered by exposure misclassification, due in part to limitations inherent in using utility sampling records. We used two exposure assessment methods, one based on ut...

  17. Exposure-dependent misclassification of exposure in interaction analyses

    DEFF Research Database (Denmark)

    Lundberg, Mats; Hallqvist, J; Diderichsen, Finn

    1999-01-01

    The objectives of this paper are to analyze the consequences of exposure misclassification on effect estimates in interaction analysis, and to develop a mathematical equation for the potentially biased estimate. The main point is to identify situations in which misclassification of the first expo...

  18. DOE Occupational Radiation Exposure, 2001 report

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2001-12-31

    The goal of the U.S. Department of Energy (DOE) is to conduct its operations, including radiological, to ensure the safety and health of all DOE employees, contractors, and subcontractors. The DOE strives to maintain radiation exposures to its workers below administrative control levels and DOE limits and to further reduce these exposures to levels that are “As Low As Reasonably Achievable” (ALARA). The 2001 DOE Occupational Radiation Exposure Report provides a summary and analysis of the occupational radiation exposure received by individuals associated with DOE activities. The DOE mission includes stewardship of the nuclear weapons stockpile and the associated facilities, environmental restoration of DOE, and energy research.

  19. Exposure of croatian population to radiopharmaceuticals

    International Nuclear Information System (INIS)

    Prlic, I.; Suric Mihic, M.; Marovic, G.; Mestrovic, T.; Mrcela, I.; Cerovac, Z.; Golubovic, D.; Hajdinjak, M.

    2010-01-01

    The aim of this paper is to call attention to the exposure of Croatian population to open sources of ionising radiation used in medical diagnostics, radiopharmaceuticals in particular, whose initial activity is very high. Without proper exposure monitoring, it is not possible to establish the effective dose per capita, but we have estimated it to be between 6.8 μSv and 7.0 μSv for this type of internal exposure, based on a very loose assumption that about 35,000 diagnostic procedures with radiopharmaceuticals are performed in Croatia every year. This calls for further research that would eventually lead to limiting the doses received through exposure to radiopharmaceuticals. (authors)

  20. Preparation and Characterization of UV-Curable Cyclohexanone-Formaldehyde Resin and Its Cured Film Properties

    Directory of Open Access Journals (Sweden)

    Guang Yang

    2014-01-01

    Full Text Available UV-curable cyclohexanone-formaldehyde (UVCF resin was prepared with cyclohexanone-formaldehyde (CF resin, isophorone diisocyanate (IPDI, and pentaerythritol triacrylate (PETA as base substance, bridging agent, and functional monomer, respectively. The structure of UVCF was characterized by Fourier transform infrared spectroscopy (FT-IR, 1H-nuclear magnetic resonance spectroscopy (1H-NMR, and gel permeation chromatography (GPC. The viscosity and photopolymerization behavior of the UV-curable formulations were studied. The thermal stability and mechanical properties of the cured films were also investigated. The results showed that UVCF resin was successfully prepared, the number of average molecular weight was about 2010, and its molecular weight distribution index was 2.8. With the increase of UVCF resin content, the viscosity of the UV-curable formulations increased. After exposure to UV irradiation for 230 s, the photopolymerization conversion of the UV-curable formulations was above 80%. Moreover, when the UVCF content was 60%, the formulations had high photopolymerization rate, and the cured UVCF films showed good thermal stability and mechanical properties.

  1. Surgery for subacromial impingement syndrome in relation to intensities of occupational mechanical exposures across 10-year exposure time windows

    DEFF Research Database (Denmark)

    Dalbøge, Annett; Frost, Poul; Andersen, Johan Hviid

    2018-01-01

    OBJECTIVES: We aimed to identify intensities of occupational mechanical exposures (force, arm elevation and repetition) that do not entail an increased risk of surgery for subacromial impingement syndrome (SIS) even after prolonged durations of exposure. Additionally, we wanted to evaluate...... if exposure to hand-arm vibration (HAV) is an independent risk factor. METHODS: We used data from a register-based cohort study of the entire Danish working population (n=2 374 403). During follow-up (2003-2008), 14 118 first-time events of surgery for SIS occurred. For each person, we linked register...... of exposure at specific intensities above minimal (low, medium and high). We used a logistic regression technique equivalent to discrete survival analysis adjusting for cumulative effects of other mechanical exposures. RESULTS: We found indications of safe exposure intensities for repetition (median angular...

  2. Delineating pMDI model reactions with loblolly pine via solution-state NMR spectroscopy. Part 1, Catalyzed reactions with wood models and wood polymers

    Science.gov (United States)

    Daniel J. Yelle; John Ralph; Charles R. Frihart

    2011-01-01

    To better understand adhesive interactions with wood, reactions between model compounds of wood and a model compound of polymeric methylene diphenyl diisocyanate (pMDI) were characterized by solution-state NMR spectroscopy. For comparison, finely ground loblolly pine sapwood, milled-wood lignin and holocellulose from the same wood were isolated and derivatized with...

  3. The mere exposure effect for visual image.

    Science.gov (United States)

    Inoue, Kazuya; Yagi, Yoshihiko; Sato, Nobuya

    2018-02-01

    Mere exposure effect refers to a phenomenon in which repeated stimuli are evaluated more positively than novel stimuli. We investigated whether this effect occurs for internally generated visual representations (i.e., visual images). In an exposure phase, a 5 × 5 dot array was presented, and a pair of dots corresponding to the neighboring vertices of an invisible polygon was sequentially flashed (in red), creating an invisible polygon. In Experiments 1, 2, and 4, participants visualized and memorized the shapes of invisible polygons based on different sequences of flashed dots, whereas in Experiment 3, participants only memorized positions of these dots. In a subsequent rating phase, participants visualized the shape of the invisible polygon from allocations of numerical characters on its vertices, and then rated their preference for invisible polygons (Experiments 1, 2, and 3). In contrast, in Experiment 4, participants rated the preference for visible polygons. Results showed that the mere exposure effect appeared only when participants visualized the shape of invisible polygons in both the exposure and rating phases (Experiments 1 and 2), suggesting that the mere exposure effect occurred for internalized visual images. This implies that the sensory inputs from repeated stimuli play a minor role in the mere exposure effect. Absence of the mere exposure effect in Experiment 4 suggests that the consistency of processing between exposure and rating phases plays an important role in the mere exposure effect.

  4. EPA EcoBox Tools by Exposure Pathways

    Science.gov (United States)

    Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

  5. Human exposure, health hazards, and environmental regulations

    International Nuclear Information System (INIS)

    Steinemann, Anne

    2004-01-01

    United States environmental regulations, intended to protect human health, generally fail to address major sources of pollutants that endanger human health. These sources are surprisingly close to us and within our control, such as consumer products and building materials that we use within our homes, workplaces, schools, and other indoor environments. Even though these indoor sources account for nearly 90% of our pollutant exposure, they are virtually unregulated by existing laws. Even pollutant levels found in typical homes, if found outdoors, would often violate federal environmental standards. This article examines the importance of human exposure as a way to understand and reduce effects of pollutants on human health. Results from exposure studies challenge traditional thinking about pollutant hazards, and reveal deficiencies in our patchwork of laws. And results from epidemiological studies, showing increases in exposure-related diseases, underscore the need for new protections. Because we cannot rely solely on regulations to protect us, and because health effects from exposures can develop insidiously, greater efforts are needed to reduce and prevent significant exposures before they occur. Recommendations include the development and use of safer alternatives to common products, public education on ways to reduce exposure, systematic monitoring of human exposure to pollutants, and a precautionary approach in decision-making

  6. Clarifying and simplifying the management of environmental exposures under different exposure situations

    International Nuclear Information System (INIS)

    Pentreath, R.J.

    2012-01-01

    The International Commission on Radiological Protection recognises three different exposure situations: planned, existing, and emergency. In all three situations, the release of radionuclides into the natural environment leads to exposures of non-human species, as well as having the potential for exposures of the general public. Each release may therefore need separate evaluations of these two consequences in order to clarify the relevant objectives of protection, their compliance with various legal requirements, and how these objectives can be achieved. However, the need to meet more than one objective should not necessarily lead to a more complicated regulatory system. Indeed, with regard to low-level routine discharges from most nuclear plants, there would appear to be scope for simplifying the entire system, to protect both humans and biota, by using discharge consent and specified radionuclide environmental quality standards for water, soil, and air in a manner similar to that used to regulate other major, non-nuclear industries. In contrast, different objectives for humans and the environment need to be set and evaluated independently for existing exposure situations. For emergency situations, the separate consequences of different management options for humans and the environment should be made clear. Should an emergency occur, it is important to have meaningful environmental criteria in order to communicate clearly with the public at large as events unfold.

  7. Exposures related to hand eczema

    DEFF Research Database (Denmark)

    Ibler, K.S.; Jemec, G.B.E.; Agner, T.

    2012-01-01

    Background. Hand eczema is common in healthcare workers, owing to intensive exposure to wet work and skin irritants. Targeted interventions and vocational guidance based on documented exposures and risk factors are needed. Objectives. The aims of the study were to investigate the relationship bet...

  8. Assessing the importance of different exposure metrics and time-activity data to predict 24-H personal PM2.5 exposures.

    Science.gov (United States)

    Chang, Li-Te; Koutrakis, Petros; Catalano, Paul J; Suh, Helen H

    Personal PM(2.5) data from two recent exposure studies, the Scripted Activity Study and the Older Adults Study, were used to develop models predicting 24-h personal PM(2.5) exposures. Both studies were conducted concurrently in the summer of 1998 and the winter of 1999 in Baltimore, MD. In the Scripted Activity Study, 1-h personal PM(2.5) exposures were measured. Data were used to identify significant factors affecting personal exposures and to develop 1-h personal exposure models for five different micro-environments. By incorporating the time-activity diary data, these models were then combined to develop a time-weighted microenvironmental personal model (model M1AD) to predict the 24-h PM(2.5) exposures measured for individuals in the Older Adults Study. Twenty-four-hour time-weighted models were also developed using 1-h ambient PM(2.5) levels and time-activity data (model A1AD) or using 24-h ambient PM(2.5) levels and time-activity data (model A24AD). The performance of these three models was compared to that using 24-h ambient concentrations alone (model A24). Results showed that factors affecting 1-h personal PM(2.5) exposures included air conditioning status and the presence of environmental tobacco smoke (ETS) for indoor micro-environments, consistent with previous studies. ETS was identified as a significant contributor to measured 24-h personal PM(2.5) exposures. Staying in an ETS-exposed microenvironment for 1 h elevated 24-h personal PM(2.5) exposures by approximately 4 microg/m 3 on average. Cooking and washing activities were identified in the winter as significant contributors to 24-h personal exposures as well, increasing 24-h personal PM(2.5) exposures by about 4 and 5 microg/m 3 per hour of activity, respectively. The ability of 3 microenvironmental personal exposure models to estimate 24-h personal PM(2.5) exposures was generally comparable to and consistently greater than that of model A24. Results indicated that using time-activity data with 1

  9. Radiation exposures: risks and realities

    International Nuclear Information System (INIS)

    Ganesh, G.

    2010-01-01

    Discovery of radioactivity in 1869 by Henry Becquerel and artificial radioactivity by Irene Curie in 1934 led to the development of nuclear field and nuclear materials in 20th century. They are widely used for man-kind across the globe in electricity production, carbon dating, treatment and diagnosis of diseases etc. While deriving benefits and utilizing nuclear resources for the benefit of man-kind, it is inevitable that exposure to radiation can not be avoided. Radiation exists all around us either natural or man-made which can not be totally eliminated or avoided. Radiation exposures from natural background contribute 2.4 to 3.6 mSv in a year. Radiation exposures incurred by a member of public due to nuclear industries constitute less than one hundredth of annual dose due to natural background. Hence it is important to understand the risk posed by radiation and comparison of radiation risk with various risks arising due to other sources. Studies have indicated that risks due to environmental pollution, cigarette smoking, alcohol consumption, heart diseases are far higher in magnitude compared to radiation risks from man made sources. This paper brings about the details and awareness regarding radiation exposures, radiation risk, various risks associated with other industries and benefits of radiation exposures. (author)

  10. Exposure Assessment Tools by Chemical Classes - Nanomaterials

    Science.gov (United States)

    EPA ExpoBox is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

  11. Major depression and secondhand smoke exposure.

    Science.gov (United States)

    Patten, Scott B; Williams, Jeanne V A; Lavorato, Dina H; Woolf, Benjamin; Wang, Jian Li; Bulloch, Andrew G M; Sajobi, Tolulope

    2018-01-01

    Epidemiological studies have consistently linked smoking to poor mental health. Among non-smokers, some studies have also reported associations between secondhand smoke exposure and psychological symptoms. However, an association between secondhand smoke exposure and depressive disorders has not been well established. This analysis used cross-sectional data from a series of 10 population surveys conducted in Canada between 2003 and 2013. The surveys targeted the Canadian household population, included a brief structured interview for past year major depressive episode (MDE) and included items assessing secondhand smoke exposure. We used two-stage individual-level random-effects meta-regression to synthesize results from these surveys. Over the study interval, about 20% of non-smokers reported substantial exposure to secondhand smoke. In this group, the pooled annual prevalence of MDE was 6.1% (95% CI 5.3-6.9) compared to 4.0% (95% CI 3.7-4.3) in non-smokers without secondhand smoke exposure. The crude odds ratio was 1.5 (95% CI 1.4-1.7). With adjustment for a set of potential confounding variables the odds ratio was unchanged, 1.4 (95% CI 1.2 - 1.6). These results provide additional support for public health measures aimed at reducing secondhand smoke exposure. A causal connection between secondhand smoke exposure and MDEs cannot be confirmed due to the cross-sectional nature of the data. Longitudinal studies are needed to establish temporal sequencing. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. The mere exposure effect with scene stimuli

    OpenAIRE

    八木 , 善彦

    2016-01-01

     The mere exposure effect refers to the phenomenon where previous exposures to stimuli increasesubsequent affective preference for those stimuli. It has been indicated that with specific stimulus-category(i.e., paintings, matrices, and photographs of scene), repeated exposure has little or oppositeeffect on affective ratings. In this study, two experiments were conducted in order to explore theeffect of stimulus-category on the mere exposure effects. Photographs of young woman’s(Experiment1)a...

  13. Subliminal exposure to faces and racial attitudes : Exposure to whites makes whites like blacks less

    NARCIS (Netherlands)

    Smith, P.K.; Dijksterhuis, A.; Chaiken, S.

    Despite recent social and political advances, most interracial contact is still superficial in nature, and White individuals interact mainly with other Whites. Based on recent mere exposure research, we propose that repeated exposure to Whites may actually increase prejudice. In a series of

  14. Quantifying human exposure to air pollution--moving from static monitoring to spatio-temporally resolved personal exposure assessment.

    Science.gov (United States)

    Steinle, Susanne; Reis, Stefan; Sabel, Clive Eric

    2013-01-15

    Quantifying human exposure to air pollutants is a challenging task. Ambient concentrations of air pollutants at potentially harmful levels are ubiquitous in urban areas and subject to high spatial and temporal variability. At the same time, every individual has unique activity-patterns. Exposure results from multifaceted relationships and interactions between environmental and human systems, adding complexity to the assessment process. Traditionally, approaches to quantify human exposure have relied on pollutant concentrations from fixed air quality network sites and static population distributions. New developments in sensor technology now enable us to monitor personal exposure to air pollutants directly while people are moving through their activity spaces and varying concentration fields. The literature review on which this paper is based on reflects recent developments in the assessment of human exposure to air pollution. This includes the discussion of methodologies and concepts, and the elaboration of approaches and study designs applied in the field. We identify shortcomings of current approaches and discuss future research needs. We close by proposing a novel conceptual model for the integrated assessment of human exposure to air pollutants taking into account latest technological capabilities and contextual information. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. UV exposure in cars.

    Science.gov (United States)

    Moehrle, Matthias; Soballa, Martin; Korn, Manfred

    2003-08-01

    There is increasing knowledge about the hazards of solar and ultraviolet (UV) radiation to humans. Although people spend a significant time in cars, data on UV exposure during traveling are lacking. The aim of this study was to obtain basic information on personal UV exposure in cars. UV transmission of car glass samples, windscreen, side and back windows and sunroof, was determined. UV exposure of passengers was evaluated in seven German middle-class cars, fitted with three different types of car windows. UV doses were measured with open or closed windows/sunroof of Mercedes-Benz E 220 T, E 320, and S 500, and in an open convertible car (Mercedes-Benz CLK). Bacillus subtilis spore film dosimeters (Viospor) were attached to the front, vertex, cheeks, upper arms, forearms and thighs of 'adult' and 'child' dummies. UV wavelengths longer than >335 nm were transmitted through car windows, and UV irradiation >380 nm was transmitted through compound glass windscreens. There was some variation in the spectral transmission of side windows according to the type of glass. On the arms, UV exposure was 3-4% of ambient radiation when the car windows were shut, and 25-31% of ambient radiation when the windows were open. In the open convertible car, the relative personal doses reached 62% of ambient radiation. The car glass types examined offer substantial protection against short-wave UV radiation. Professional drivers should keep car windows closed on sunny days to reduce occupational UV exposure. In individuals with polymorphic light eruption, produced by long-wave UVA, additional protection by plastic films, clothes or sunscreens appears necessary.

  16. Extreme Precipitation and Flooding: Exposure Characterization and the Association Between Exposure and Mortality in 108 United States Communities, 1987-2005

    Science.gov (United States)

    Severson, R. L.; Peng, R. D.; Anderson, G. B.

    2017-12-01

    There is substantial evidence that extreme precipitation and flooding are serious threats to public health and safety. These threats are predicted to increase with climate change. Epidemiological studies investigating the health effects of these events vary in the methods used to characterize exposure. Here, we compare two sources of precipitation data (National Oceanic and Atmospheric Administration (NOAA) station-based and North American Land Data Assimilation Systems (NLDAS-2) Reanalysis data-based) for estimating exposure to extreme precipitation and two sources of flooding data, based on United States Geological Survey (USGS) streamflow gages and the NOAA Storm Events database. We investigate associations between each of the four exposure metrics and short-term risk of four causes of mortality (accidental, respiratory-related, cardiovascular-related, and all-cause) in the United States from 1987 through 2005. Average daily precipitation values from the two precipitation data sources were moderately correlated (Spearman's rho = 0.74); however, values from the two data sources were less correlated when comparing binary metrics of exposure to extreme precipitation days (Jaccard index (J) = 0.35). Binary metrics of daily flood exposure were poorly correlated between the two flood data sources (Spearman's rho = 0.07; J = 0.05). There was little correlation between extreme precipitation exposure and flood exposure in study communities. We did not observe evidence of a positive association between any of the four exposure metrics and risk of any of the four mortality outcomes considered. Our results suggest, due to the observed lack of agreement between different extreme precipitation and flood metrics, that exposure to extreme precipitation may not serve as an effective surrogate for exposures related to flooding. Furthermore, It is possible that extreme precipitation and flood exposures may often be too localized to allow accurate exposure assessment at the

  17. Radio frequency exposure in mobile phone users: Implications for exposure assessment in epidemiological studies

    International Nuclear Information System (INIS)

    Morrissey, J. J.

    2007-01-01

    The majority of epidemiological studies investigating correlations between long-term low-level radiofrequency (RF) exposure from mobile phones and health endpoints have followed a case-control design, requiring reconstruction of individual RF exposure. To date, these have employed 'time of use' as an exposure surrogate from questionnaire information or billing records. The present study demonstrates such an approach may not account for variability in mobile phone transmit power, which can be roughly correlated with RF exposure. This variability exists (a) during a single call, (b) between separate calls, (c) between averaged values from individuals within a local study group and (d) between average values from groups in different geographical locations. The present data also suggest an age-related influence on talk time, as well as significant inaccuracy (45-60%) in recalling 'time of use'. Evolving technology and changing use behaviours may add additional complexities. Collectively, these data suggest efforts to identify dose response and statistical correlations between mobile phone use and subtle health endpoints may be significantly challenged. (authors)

  18. Cellular responses to tritium exposure in rainbow trout: HTO- and OBT-spiked feed exposure experiments

    Energy Technology Data Exchange (ETDEWEB)

    Festarini, A.; Shultz, C.; Stuart, M.; Kim, S.B., E-mail: amy.festarini@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Ferreri, C. [National Research Council of Italy, Dept. of Chemical Sciences and Materials Technologies, Bologna (Italy)

    2016-06-15

    Biological effects were evaluated in rainbow trout (Oncorhynchus mykiss) exposed to tritiated water (HTO) or food spiked with organically bound tritium (OBT). An HTO exposure study was conducted using a tritium activity concentration of 7000 Bq/L, and an OBT exposure study was conducted using a tritium activity concentration of 30 000 Bq/L. Following 140 days of in vivo HTO exposure, liver, heart, spleen, kidney, and brain cells did not show statistically significant differences in viability; kidney, liver, and spleen cells did not show significant differences in DNA double-strand break repair activity compared with control cells. Membrane fatty acid composition analysis was conducted on liver cells and no effects of HTO exposure could be detected. Following 140 days of in vivo OBT exposure, viability and DNA double-strand break repair activity were not statistically different from controls in liver, heart, spleen, kidney, and brain cells. Changes, however, were noted in the fatty acid composition of liver and muscle tissues. For both studies, all measurements were performed on each tissue and on a fraction of the same tissue that was exposed to a gamma 4 Gy dose in vitro to test for adaptive responses, and no effects were observed except for fatty acid composition. The findings demonstrated that membrane fatty acid composition is a sensitive marker and that microscopic evaluation of gamma-H2AX foci is more sensitive than the flow cytometric approach. These studies are the first to correlate uptake and depuration with biological health indicators in edible fish for tritium exposures within worldwide drinking water guidelines. (author)

  19. Cellular responses to tritium exposure in rainbow trout: HTO- and OBT-spiked feed exposure experiments

    International Nuclear Information System (INIS)

    Festarini, A.; Shultz, C.; Stuart, M.; Kim, S.B.; Ferreri, C.

    2016-01-01

    Biological effects were evaluated in rainbow trout (Oncorhynchus mykiss) exposed to tritiated water (HTO) or food spiked with organically bound tritium (OBT). An HTO exposure study was conducted using a tritium activity concentration of 7000 Bq/L, and an OBT exposure study was conducted using a tritium activity concentration of 30 000 Bq/L. Following 140 days of in vivo HTO exposure, liver, heart, spleen, kidney, and brain cells did not show statistically significant differences in viability; kidney, liver, and spleen cells did not show significant differences in DNA double-strand break repair activity compared with control cells. Membrane fatty acid composition analysis was conducted on liver cells and no effects of HTO exposure could be detected. Following 140 days of in vivo OBT exposure, viability and DNA double-strand break repair activity were not statistically different from controls in liver, heart, spleen, kidney, and brain cells. Changes, however, were noted in the fatty acid composition of liver and muscle tissues. For both studies, all measurements were performed on each tissue and on a fraction of the same tissue that was exposed to a gamma 4 Gy dose in vitro to test for adaptive responses, and no effects were observed except for fatty acid composition. The findings demonstrated that membrane fatty acid composition is a sensitive marker and that microscopic evaluation of gamma-H2AX foci is more sensitive than the flow cytometric approach. These studies are the first to correlate uptake and depuration with biological health indicators in edible fish for tritium exposures within worldwide drinking water guidelines. (author)

  20. Americans' Average Radiation Exposure

    International Nuclear Information System (INIS)

    2000-01-01

    We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body

  1. Ultrafine particle exposure in Danish residencies

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Karottki, Dorina Gabriela; Wierzbicka, Aneta

    2016-01-01

    candle burning, cooking, toasting and unknown activities, were responsible on average for ∼65% of the residential integrated exposure. Residents of another 60 homes were then asked to carry a backpack equipped with a GPS recorder and a portable monitor to measure real-time individual exposure over ~48 h...... personal exposure, indoor environments other than home or vehicles contributed with ~40%, and being in transit or outdoors contributed 5% or less....

  2. Volatility Exposure for Strategic Asset Allocation

    OpenAIRE

    Briere, Marie; Burgues, Alexandre; Signori, Ombretta

    2008-01-01

    This paper examines the advantages of incorporating strategic exposure to equity volatility into the investment-opportunity set of a long-term equity investor. We consider two standard volatility investments: implied volatility and volatility risk premium strategies. To calibrate and assess the risk/return profile of the portfolio, we present an analytical framework offering pragmatic solutions for long-term investors seeking exposure to volatility. The benefit of volatility exposure for a co...

  3. DOE 2012 occupational radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2013-10-01

    The U.S. Department of Energy (DOE) Office of Analysis within the Office of Health, Safety and Security (HSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE (including the National Nuclear Security Administration [NNSA]). The DOE 2012 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with Title 10, Code of Federal Regulations (C.F.R.), Part 835, Occupational Radiation Protection dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protection of individuals from the adverse health effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. Over the past 5-year period, the occupational radiation exposure information is analyzed in terms of aggregate data, dose to individuals, and dose by site.

  4. DOE 2011 occupational radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-12-01

    The U.S. Department of Energy (DOE) Office of Analysis within the Office of Health, Safety and Security (HSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE (including the National Nuclear Security Administration [NNSA]). The DOE 2011 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with Title 10, Code of Federal Regulations (C.F.R.), Part 835, Occupational Radiation Protection dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protection of individuals from the adverse health effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. The occupational radiation exposure information is analyzed in terms of aggregate data, dose to individuals, and dose by site over the past five years.

  5. Techniques for controlling radiation exposure

    International Nuclear Information System (INIS)

    Ocken, H.; Wood, C.J.

    1993-01-01

    The US nuclear power industry has been remarkably successful in reducing worker radiation exposure over the past 10 years. There has been more than a fourfold reduction in person-rem per MW-year of electric power generated: from 1.8 person-rems in 1980 to only 0.4 person-rems in 1991. Despite this substantial improvement, challenges for the industry remain. Individual exposure limits have been tightened in the 1990 Recommendations of the International Commission on Radiological Protection, ICRP Publication 60, and there will be more requirements for special maintenance work as plants age, suggesting that vigorous efforts will be required to meet the 1995 industry goals for unit median collective exposure. No one method will suffice, but implementing suitable combinations from this compendium will help utilities to achieve their exposure goals. Radiation reduction is generally cost-effective: Outages are shorter, staffing requirements are reduced, and work quality is improved. Despite up-front costs, the benefits over the following one to three years typically outweigh the expenses

  6. DOE 2013 occupational radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2014-11-01

    The Office of Analysis within the U.S. Department of Energy (DOE) Office of Environment, Health, Safety and Security (EHSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE (including the National Nuclear Security Administration [NNSA]). The DOE 2013 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with Title 10, Code of Federal Regulations (C.F.R.), Part 835, Occupational Radiation Protection dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protection of individuals from the adverse health effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. Over the past five-year period, the occupational radiation exposure information has been analyzed in terms of aggregate data, dose to individuals, and dose by site.

  7. Fetal exposure in diagnostic radiology

    International Nuclear Information System (INIS)

    Baker, M.L.; Vandergrift, J.F.; Dalrymple, G.V.

    1979-01-01

    The problem of possible radiation damage to the fetus or embryo as a result of diagnostic radiography during pregnancy, particularly in the early stages, is discussed. Recommendations of therapeutic abortion after fetal exposure require an adequate knowledge of the doses involved. In the absence of actual dose measurements or estimates, approximate exposure levels may be determined from the literature. A summary of published values for radiography involving the lower abdomen is given. Data is also presented from a series of fetal exposures resulting mostly from routine diagnostic radiography when pregnancy was not known at the time but was established later. Results of actual dose measurements using a phantom and of dose calculations based on published values are in reasonable agreement indicating that literature values of dose provide a satisfactory alternative to measurement. These data suggest that diagnostic radiography rarely, if ever, results in fetal exposures high enough to justify therapeutic abortion. (author)

  8. Specific requirements for public exposure in medical practice

    International Nuclear Information System (INIS)

    Fernandez Gomez, Isis Maria

    2012-01-01

    The cause of radiation sources, by exposure to the public, has excluded all those medical and occupational exposures and exposure to natural background radiation normal, in the area. The main sources of public exposure that have found are: practices, discharges or spills, food or merchandise contaminated, chronic exposure scenarios (radon, NORM), waste management (predisposal management, storage, disposal). Public exposure can occur in two forms. One has been by procedure: transport, storage, handling of sources, radioactive waste, radioactive patient. The second has been per incident: transportation accidents, loss of sources, spread of contamination, unchecked pollution. (author) [es

  9. The Exposure Advantage: Early Exposure to a Multilingual Environment Promotes Effective Communication.

    Science.gov (United States)

    Fan, Samantha P; Liberman, Zoe; Keysar, Boaz; Kinzler, Katherine D

    2015-07-01

    Early language exposure is essential to developing a formal language system, but may not be sufficient for communicating effectively. To understand a speaker's intention, one must take the speaker's perspective. Multilingual exposure may promote effective communication by enhancing perspective taking. We tested children on a task that required perspective taking to interpret a speaker's intended meaning. Monolingual children failed to interpret the speaker's meaning dramatically more often than both bilingual children and children who were exposed to a multilingual environment but were not bilingual themselves. Children who were merely exposed to a second language performed as well as bilingual children, despite having lower executive-function scores. Thus, the communicative advantages demonstrated by the bilinguals may be social in origin, and not due to enhanced executive control. For millennia, multilingual exposure has been the norm. Our study shows that such an environment may facilitate the development of perspective-taking tools that are critical for effective communication. © The Author(s) 2015.

  10. Integrated Environmental Assessment Part III: ExposureAssessment

    Energy Technology Data Exchange (ETDEWEB)

    McKone, Thomas E.; Small, Mitchell J.

    2006-06-01

    Human exposure assessment is a key step in estimating the environmental and public health burdens that result chemical emissions in the life cycle of an industrial product or service. This column presents the third in a series of overviews of the state of the art in integrated environmental assessment - earlier columns described emissions estimation (Frey and Small, 2003) and fate and transport modeling (Ramaswami, et al., 2004). When combined, these first two assessment elements provide estimates of ambient concentrations in the environment. Here we discuss how both models and measurements are used to translate ambient concentrations into metrics of human and ecological exposure, the necessary precursors to impact assessment. Exposure assessment is the process of measuring and/or modeling the magnitude, frequency and duration of contact between a potentially harmful agent and a target population, including the size and characteristics of that population (IPCS, 2001; Zartarian, et al., 2005). Ideally the exposure assessment process should characterize the sources, routes, pathways, and uncertainties in the assessment. Route of exposure refers to the way that an agent enters the receptor during an exposure event. Humans contact pollutants through three routes--inhalation, ingestion, and dermal uptake. Inhalation occurs in both outdoor environments and indoor environments where most people spend the majority of their time. Ingestion includes both water and food, as well as soil and dust uptake due to hand-to-mouth activity. Dermal uptake occurs through contacts with consumer products; indoor and outdoor surfaces; the water supply during washing or bathing; ambient surface waters during swimming or boating; soil during activities such as work, gardening, and play; and, to a lesser extent, from the air that surrounds us. An exposure pathway is the course that a pollutant takes from an ambient environmental medium (air, soil, water, biota, etc), to an exposure medium

  11. Attentional modulation of the mere exposure effect

    OpenAIRE

    Yagi, Yoshihiko; Ikoma, Shinobu; Kikuchi, Tadashi

    2009-01-01

    The mere exposure effect refers to the phenomenon where previous exposures to stimuli increase participants’ subsequent affective preference for those stimuli. This study explored the effect of selective attention on the mere exposure effect. The experiments manipulated the to-be-attended drawings in the exposure period (either red or green polygons in Experiments 1 and 2; both red and green polygons in Experiments 3 and 4) and black to-be-evaluated drawings in the affective judgment period (...

  12. When is exposure to a natural disaster traumatic? Comparison of a trauma questionnaire and disaster exposure inventory.

    Directory of Open Access Journals (Sweden)

    Emily W Harville

    Full Text Available Few studies have compared the sensitivity of trauma questionnaires to disaster inventories for assessing the prevalence of exposure to natural disaster or associated risk for post-disaster psychopathology. The objective of this analysis was to compare reporting of disaster exposure on a trauma questionnaire (Brief Trauma Questionnaire [BTQ] to an inventory of disaster experience. Between 2011 and 2014, a sample of 841 reproductive-aged southern Louisiana women were interviewed using the BTQ and completed a detailed inventory about exposure to hurricanes and flooding. Post-traumatic stress disorder (PTSD symptomology was measured with the Post-Traumatic Stress Checklist, and depression with the Edinburgh Depression Scale. The single question addressing disaster exposure on the BTQ had a sensitivity of between 65% and 70% relative to the more detailed questions. Reporting disaster exposure on the BTQ was more likely for those who reported illness/injury due to a hurricane or flood (74%-77% or danger (77-79%, compared to those who reported damage (69-71% or evacuation (64-68%. Reporting disaster exposure on the BTQ was associated with depression (odds ratio [OR] 2.29, 95% confidence interval [CI] 1.43-3.68. A single question is unlikely to be useful for assessing the degree of exposure to disaster across a broad population, and varies in utility depending on the mental health outcome of interest: the single trauma question is useful for assessing depression risk.

  13. Gas-phase organics in environmental tobacco smoke: 2. Exposure-relevant emission factors and indirect exposures from habitual smoking

    Science.gov (United States)

    Singer, Brett C.; Hodgson, Alfred T.; Nazaroff, William W.

    Sorption of emitted gas-phase organic compounds onto material surfaces affects environmental tobacco smoke (ETS) composition and exposures indoors. We have introduced a new metric, the exposure relevant emission factor (EREF) that accounts for sorptive uptake and reemission to give the mass of individual ETS constituents available for exposure over a day in which smoking occurs. This paper describes month-long experiments to investigate sorption effects on EREFs and potential ETS exposures under habitual smoking conditions. Cigarettes were smoked in a 50-m 3 furnished room over a 3-h period 6-7 days per week, with continuous ventilation at 0.3, 0.6, or 2.1 h -1. Organic gas concentrations were measured every few days over 4-h "smoking", 10-h "post-smoking" and 10-h "background" periods. Concentration patterns of volatile ETS components including 1,3-butadiene, benzene and acrolein were similar to those calculated for a theoretical non-sorbing tracer, indicating limited sorption. Concentrations of ETS tracers, e.g. 3-ethenylpyridine (3-EP) and nicotine, and lower volatility toxic air contaminants including phenol, cresols, and naphthalene increased as experiments progressed, indicating mass accumulation on surfaces and higher desorption rates. Daily patterns stabilized after week 2, yielding a steady daily cycle of ETS concentrations associated with habitual smoking. EREFs for sorbing compounds were higher under steady cycle versus single-day smoking conditions by ˜50% for 3-EP, and by 2-3 times for nicotine, phenol, cresols, naphthalene, and methylnaphthalenes. Our results provide relevant information about potential indirect exposures from residual ETS (non-smoker enters room shortly after smoker finishes) and from reemission, and their importance relative to direct exposures (non-smoker present during smoking). Under the conditions examined, indirect exposures accounted for a larger fraction of total potential exposures for sorbing versus non-sorbing compounds

  14. Developmental toxicity of prenatal exposure to toluene.

    Science.gov (United States)

    Bowen, Scott E; Hannigan, John H

    2006-01-01

    Organic solvents have become ubiquitous in our environment and are essential for industry. Many women of reproductive age are increasingly exposed to solvents such as toluene in occupational settings (ie, long-term, low-concentration exposures) or through inhalant abuse (eg, episodic, binge exposures to high concentrations). The risk for teratogenic outcome is much less with low to moderate occupational solvent exposure compared with the greater potential for adverse pregnancy outcomes, developmental delays, and neurobehavioral problems in children born to women exposed to high concentrations of abused organic solvents such as toluene, 1,1,1-trichloroethane, xylenes, and nitrous oxide. Yet the teratogenic effects of abuse patterns of exposure to toluene and other inhalants remain understudied. We briefly review how animal models can aid substantially in clarifying the developmental risk of exposure to solvents for adverse biobehavioral outcomes following abuse patterns of use and in the absence of associated health problems and co-drug abuse (eg, alcohol). Our studies also begin to establish the importance of dose (concentration) and critical perinatal periods of exposure to specific outcomes. The present results with our clinically relevant animal model of repeated, brief, high-concentration binge prenatal toluene exposure demonstrate the dose-dependent effect of toluene on prenatal development, early postnatal maturation, spontaneous exploration, and amphetamine-induced locomotor activity. The results imply that abuse patterns of toluene exposure may be more deleterious than typical occupational exposure on fetal development and suggest that animal models are effective in studying the mechanisms and risk factors of organic solvent teratogenicity.

  15. Environmental exposure to asbestos: from geology to mesothelioma.

    Science.gov (United States)

    Bayram, Mehmet; Bakan, Nur Dilek

    2014-05-01

    This article aims to review the geological background of environmental asbestos exposure and the distribution of asbestos-related disease (ARD) in association with naturally occurring asbestos (NOA), and discusses the potential health risks associated with exposure to non-occupational asbestos. With the motion of continental and oceanic plates, in some parts of the world serpentinites in the lower layer of the oceanic plate move into the continental plate and form the so-called ophiolites. Ophiolites consist of soil and rocks containing serpentine-type asbestos. There is an increase in ARDs in regions close to ophiolites. Indoor exposure and outdoor exposure to NOA, outdoor exposure to industrial asbestos and mines, urbanization and construction works in NOA regions are the known sources and types of environmental asbestos exposure. Although there is an expectance of decline in ARDs caused by industrial exposure to asbestos, the environmental exposure to asbestos is still a challenge waiting to be overcome.

  16. Exposure Knowledge and Perception of Wireless Communication Technologies

    Directory of Open Access Journals (Sweden)

    Frederik Freudenstein

    2015-11-01

    Full Text Available The presented survey investigates risk and exposure perceptions of radio frequency electromagnetic fields (RF EMF associated with base stations, mobile phones and other sources, the key issue being the interaction between both sets of perceptions. The study is based on a cross-sectional design, and conducted with an online sample of 838 citizens from Portugal. The results indicate that respondents’ intuitive exposure perception differs from the actual exposure levels. Furthermore, exposure and risk perceptions are found to be highly correlated. Respondents’ beliefs  about exposure factors, which might influence possible health risks, is appropriate. A regression analysis between exposure characteristics, as predictor variables, and RF EMF risk perception, as the response variable, indicates that people seem to use simple heuristics to form their perceptions. What is bigger, more frequent and longer lasting is seen as riskier. Moreover, the quality of exposure knowledge is not an indicator for amplified EMF risk perception. These findings show that exposure perception is key to future risk communication.

  17. Task-based dermal exposure models for regulatory risk assessment.

    Science.gov (United States)

    Warren, Nicholas D; Marquart, Hans; Christopher, Yvette; Laitinen, Juha; VAN Hemmen, Joop J

    2006-07-01

    The regulatory risk assessment of chemicals requires the estimation of occupational dermal exposure. Until recently, the models used were either based on limited data or were specific to a particular class of chemical or application. The EU project RISKOFDERM has gathered a considerable number of new measurements of dermal exposure together with detailed contextual information. This article describes the development of a set of generic task-based models capable of predicting potential dermal exposure to both solids and liquids in a wide range of situations. To facilitate modelling of the wide variety of dermal exposure situations six separate models were made for groupings of exposure scenarios called Dermal Exposure Operation units (DEO units). These task-based groupings cluster exposure scenarios with regard to the expected routes of dermal exposure and the expected influence of exposure determinants. Within these groupings linear mixed effect models were used to estimate the influence of various exposure determinants and to estimate components of variance. The models predict median potential dermal exposure rates for the hands and the rest of the body from the values of relevant exposure determinants. These rates are expressed as mg or microl product per minute. Using these median potential dermal exposure rates and an accompanying geometric standard deviation allows a range of exposure percentiles to be calculated.

  18. Joint analysis of French and Czech uranium miners: lung cancer risk at low radon exposure rates and modifying effects of time since exposure and age at exposure

    International Nuclear Information System (INIS)

    Ladislav Tomasek; Agnes Rogel; Margot Tirmarche; Dominique Laurier

    2006-01-01

    The present analysis was conducted in the frame of European project 'Quantification of lung cancer risk after low radon exposure and low exposure rate: synthesis from epidemiologic and experimental data'. The overall goal of the project related to uranium miners was the evaluation of lung cancer dose-response relationship and of dose rate effects among European uranium miners exposed to low doses and low dose rates of radon decay products. In addition, modifying factors like attained age, age at exposure and time since exposure were investigated. The joint analysis of French and Czech uranium miners was conducted mainly in order to increase the statistical power and to allow a more detailed description of the variation of dose-response relationship in time. (N.C.)

  19. Joint analysis of French and Czech uranium miners: lung cancer risk at low radon exposure rates and modifying effects of time since exposure and age at exposure

    Energy Technology Data Exchange (ETDEWEB)

    Ladislav Tomasek [National Radiation Protection Institute, Prague (Czech Republic); Agnes Rogel; Margot Tirmarche; Dominique Laurier [Institut de Radioprotection et de Surete Nucleaire, Fontenay-aux-Roses (France)

    2006-07-01

    The present analysis was conducted in the frame of European project 'Quantification of lung cancer risk after low radon exposure and low exposure rate: synthesis from epidemiologic and experimental data'. The overall goal of the project related to uranium miners was the evaluation of lung cancer dose-response relationship and of dose rate effects among European uranium miners exposed to low doses and low dose rates of radon decay products. In addition, modifying factors like attained age, age at exposure and time since exposure were investigated. The joint analysis of French and Czech uranium miners was conducted mainly in order to increase the statistical power and to allow a more detailed description of the variation of dose-response relationship in time. (N.C.)

  20. In-depth methods for systemic exposure predictions

    Science.gov (United States)

    Exposure to a wide range of chemicals is ubiquitous and largely unavoidable within modern society. The potential for human exposure, however, has not been quantified for the vast majority of chemicals with wide commercial use. Creative advances in exposure science are needed to s...

  1. Transient threshold shift after gunshot noise exposure.

    Science.gov (United States)

    Saedi, B; Ghasemi, M; Motiee, M; Mojtahed, M; Safavi, A

    2013-01-01

    Many people, such as soldiers, are routinely exposed to gunshot noise during target practice. It is suspected that this high-intensity noise may affect audition through repeated Transient Threshold Shifts (TTS); it can also mechanically alter auditory components such as waves. This study investigates the scope of gunshot noise from the AK-47 rifle (Kalashnikov) and the impact on the shooters' audition. Forty soldiers (80 ears) were recruited in this study. They were all young and being exposed to gunshot noise for the first time. Gunshot characteristics were measured before exposure. The soldiers underwent auditory evaluation with Pure Tone Audiometry (PTA) and Oto-Acoustic Emission (OAE) once before exposure and immediately (less than one hour) after exposure. The AK-47 gunshot noise pressure level varied between L(AIm) = 73.7 dBA to L(AIm) = 111.4 dBA. Fourteen participants had subclinical hearing impairment in their pre-exposure evaluation; this number increased to 16 after the exposure. Six months post-exposure and later, the number of cases with impairment had fallen to eight (improvement in 50%). Both pre- and post-exposure OAE results were within normal values, while PTA results indicated a significant threshold alteration only at 6 kHz. The results of this study confirm that exposure to gunshot noise with no ear protection can represent a significant hazard for auditory function, especially at higher frequencies.

  2. Mercury Exposure and Heart Diseases

    Science.gov (United States)

    Genchi, Giuseppe; Sinicropi, Maria Stefania; Carocci, Alessia; Lauria, Graziantonio; Catalano, Alessia

    2017-01-01

    Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive, and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease, and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence has shown that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system. PMID:28085104

  3. Mercury Exposure and Heart Diseases.

    Science.gov (United States)

    Genchi, Giuseppe; Sinicropi, Maria Stefania; Carocci, Alessia; Lauria, Graziantonio; Catalano, Alessia

    2017-01-12

    Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive, and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease, and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence has shown that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system.

  4. Mercury Exposure and Heart Diseases

    Directory of Open Access Journals (Sweden)

    Giuseppe Genchi

    2017-01-01

    Full Text Available Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive, and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease, and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence has shown that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system.

  5. Patient radiation exposure dose evaluation of whole spine scanography due to exposure direction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Su; Seo, Deok Nam [Dept. of Bio-convergence Engineering, Graduate School of Korea University, Seoul (Korea, Republic of); Kwon, Soon Mu [Dept. of Radiologic Technology, Daegu Health College, Daegu (Korea, Republic of); Kim, Jung Min [Dept. of Radiological Science, Korea University, Seoul (Korea, Republic of)

    2015-04-15

    Whole spine scanography (WSS) is a radiological examination that exposes the whole body of the individual being examined to x-ray radiation. WSS is often repeated during the treatment period, which results in a much greater radiation exposure than that in routine x-ray examinations. The aims of the current study were to evaluate the patient dose of WSS using computer simulation, image magnification and angulation of phantom image using different patient position. We evaluated the effective dose(ED) of 23 consecutive patients (M : F = 13:10) who underwent WSS, based on the automatic image pasting method for multiple exposure digital radiography. The Anterior-Posterior position(AP) and Posterior-Anterior position( PA) projection EDs were evaluated based on the PC based Monte Carlo simulation. We measured spine transverse process distance and angulation using DICOM measurement. For all patient, the average ED was 0.069 mSv for AP position and 0.0361 mSv for PA position. AP position calculated double exposure then PA position. For male patient, the average ED was 0.089 mSv(AP) and 0.050 mSv(PA). For female patient, the average ED was 0.0431 mSv(AP) and 0.026 mSv(PA). The transverse process of PA spine image measured 5% higher than AP but angulation of transverse process was no significant differences. In clinical practice, just by change the patient position was conformed to reduce the ED of patient. Therefore we need to redefine of protocol for digital radiography such as WSS, whole spine scanography, effective dose, patient exposure dose, exposure direction, protocol optimization.

  6. The diesel exhaust in miners study: II. Exposure monitoring surveys and development of exposure groups.

    NARCIS (Netherlands)

    Coble, J.B.; Stewart, P.A.; Vermeulen, R.; Yereb, D.; Stanevich, R.; Blair, A.; Silverman, D.T.; Attfield, M.

    2010-01-01

    Air monitoring surveys were conducted between 1998 and 2001 at seven non-metal mining facilities to assess exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), for an epidemiologic study of miners exposed to DE. Personal exposure measurements were taken on workers in a

  7. Development of novel whole-body exposure setups for rats providing high efficiency, National Toxicology Program (NTP) compatibility and well-characterized exposure

    Energy Technology Data Exchange (ETDEWEB)

    Kainz, Wolfgang [Food and Drug Administration (FDA), Center for Devices and Radiological Health (CDRH), 12725 Twinbrook Parkway, Rockville, MD 20852 (United States); Nikoloski, Neviana [IT' IS Foundation-The Foundation for Research on Information Technologies in Society, ETH Zurich, 8092 Zurich (Switzerland); Oesch, Walter [IT' IS Foundation-The Foundation for Research on Information Technologies in Society, ETH Zurich, 8092 Zurich (Switzerland); Berdinas-Torres, Veronica [IT' IS Foundation-The Foundation for Research on Information Technologies in Society, ETH Zurich, 8092 Zurich (Switzerland); Froehlich, Juerg [IT' IS Foundation-The Foundation for Research on Information Technologies in Society, ETH Zurich, 8092 Zurich (Switzerland); Neubauer, Georg [ARC Seibersdorf research GmbH, Kramergasse 1, A-1010 Vienna (Austria); Kuster, Niels [IT' IS Foundation-The Foundation for Research on Information Technologies in Society, ETH Zurich, 8092 Zurich (Switzerland)

    2006-10-21

    This paper presents the design, optimization, realization and verification of novel whole-body exposure setups for rats. The setups operating at 902 MHz and 1747 MHz provide highly efficient, National Toxicology Program (NTP) compatible and well-characterized exposures. They are compared to existing concepts of exposure setups with respect to efficiency, induced field uniformity, good laboratory practice (GLP) compatibility and cost. The novel exposure setup consists of a circular cascade of 17 sectorial waveguides excited by a novel loop antenna placed in the centre. The 70% overall efficiency of the exposure setup surpasses comparable values of existing setups. A field uniformity inside the phantom of more than 86% for the 1g cubical averaged specific absorption rate (SAR) within {+-}5 dB of the whole-body SAR (WB-SAR) was attained. The uniformity of the exposure inside the setup, defined as the variation of the WB-SAR between animals, was better than {+-}24%. Using only stainless steel, gold and polycarbonate in the vicinity of the animals ensured full GLP compatibility. The entire exposure system features fully automated computer controlled exposure and data monitoring, data storing and failure handling. Therefore, the proposed exposure system can be used to run blinded large scale, long-term exposure studies.

  8. Variability and uncertainty in Swedish exposure factors for use in quantitative exposure assessments.

    Science.gov (United States)

    Filipsson, Monika; Öberg, Tomas; Bergbäck, Bo

    2011-01-01

    Information of exposure factors used in quantitative risk assessments has previously been compiled and reported for U.S. and European populations. However, due to the advancement of science and knowledge, these reports are in continuous need of updating with new data. Equally important is the change over time of many exposure factors related to both physiological characteristics and human behavior. Body weight, skin surface, time use, and dietary habits are some of the most obvious examples covered here. A wealth of data is available from literature not primarily gathered for the purpose of risk assessment. Here we review a number of key exposure factors and compare these factors between northern Europe--here represented by Sweden--and the United States. Many previous compilations of exposure factor data focus on interindividual variability and variability between sexes and age groups, while uncertainty is mainly dealt with in a qualitative way. In this article variability is assessed along with uncertainty. As estimates of central tendency and interindividual variability, mean, standard deviation, skewness, kurtosis, and multiple percentiles were calculated, while uncertainty was characterized using 95% confidence intervals for these parameters. The presented statistics are appropriate for use in deterministic analyses using point estimates for each input parameter as well as in probabilistic assessments. © 2010 Society for Risk Analysis.

  9. Radiation exposure in medicare-occupational and medical exposure

    International Nuclear Information System (INIS)

    Morozumi, Kunihiko

    2012-01-01

    Recent cases of the occupational and medical exposures are discussed in relation to the justification of practice, optimization of protection and effort to reduce the dose. Instances of the occupational exposure in doctors and nurses like 26.5 mSv/15 mo and 53.9 mSv/y, and of skin cancer were reported in newspapers of 1999-2004, which might have had been prevented by their self evaluation of daily and monthly exposed dose. For reasonably lowering the occupational dose and number of exposed stuff in the present law, the prior radiation protection measures are to be taken in consideration of social/economical factors to conduct beneficial radiation medicare without restriction of practice under safest conditions, protecting personal determinative hazard and preventing stochastic effect. Medical stuff must be equipped with personal dosimeter. Further, recent media also commented such cases as unwished abortions after careless X-CT of pregnant women, and risk of increased cancer prevalence (3.2% in Japan) due to medical exposure, etc (200-2010). The prevalence is calculated on the linear non-threshold (LNT) hypothesis and is probably overestimated, possibly causing patient's fear. There has been a history of proposal by IAEA (1996) of the guidance levels of the ordinary roentgenography and in vivo nuclear medical test, and introduction of the concept of dose constraint by ICRP (Pub. 60). The incident dose rate to the patient under fluoroscopy defined by Japan Medical Service Law (2001) is, as an air-kerma rate, 15,600 residents for their contamination as well as remains, and measured the ambient dose rate of cities nearby. (T.T.)

  10. Measuring exposure to organochlorinated pesticides

    Directory of Open Access Journals (Sweden)

    Gulnar Azevedo e Silva Mendonça

    1998-01-01

    Full Text Available Environmental epidemiological investigations in cancer remain, with rare exceptions, inconclusive. The difficulties of establishing patterns of measurements of exposure in the human body is one of the limitations of these studies. The findings of six recent epidemiological studies that analyzed the association between organochlorinated compounds and breast cancer are reviewed in considering the problems of measuring environmental exposure through biological markers. The epidemiological evidence based on these studies do not indicate a risk of breast cancer related to organochlorines. Some aspects that may partially explain this absence of risk are discussed regarding the investigation of environmental carcinogenic agents in populations with low but homogeneously sprayed levels of exposure.

  11. Management of exposure to waste anesthetic gases.

    Science.gov (United States)

    Smith, Francis Duval

    2010-04-01

    Anesthetic agents were developed in the 1700s, and nitrous oxide was first used in 1884. Research on the effects of waste anesthetic gas exposure started appearing in the literature in 1967. Short-term exposure causes lethargy and fatigue, and long-term exposure may be linked to spontaneous abortion, congenital abnormalities, infertility, premature births, cancer, and renal and hepatic disease. Today, perioperative staff members are exposed to trace amounts of waste anesthetic gas, and although this exposure cannot be eliminated, it can be controlled. Health care facilities are required to develop, implement, measure, and control practices to reduce anesthetic gas exposure to the lowest practical level. Exposure levels must be measured every six months and maintained at less than 25 parts per million for nitrous oxide and 2 parts per million for halogenated agents to be compliant with Occupational Safety and Health Administration standards. Copyright 2010 AORN, Inc. Published by Elsevier Inc. All rights reserved.

  12. 1976 Hanford Americium exposure incident: hematologic effects

    International Nuclear Information System (INIS)

    Ragan, H.A.; Mahaffey, J.A.; Breitenstein, B.D.

    1982-05-01

    Hematologic evaluation of an individual with an initial systemic body burden of approx. 200 μCi 241 Am revealed a significant (P < 0.01) reduction of total leukocytes, neutrophils, and lymphocytes. This effect on total leukocytes and neutrophils was evident approx. 30 days after exposure, appeared to stabilize at about 3 months after exposure, and remained at this lower level thorugh a 52-months observation period. The effect on lymphocytes was apparent by 3 days after exposure, stabilizing at approx. 50% of pre-exposure values for about 7 months, with a return to pre-exposure levels in the following 4 y. There was a progressive and significant (P < 0.001) decline in platelet counts during the 52-months postexposure period. The pattern of response in erythrocyte parameters was complex. Immediately after the accident, these values were less than the pre-exposure mean level; they gradually increased (P < 0.001) for approx. 2 y and then began a progressive decline (P < 0.001)

  13. Effects of prenatal exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Miller, R.W.

    1990-01-01

    Prenatal exposure to ionizing radiation induces some effects that are seen at birth and others that cannot be detected until later in life. Data from A-bomb survivors in Hiroshima and Nagasaki show a diminished number of births after exposure under 4 wk of gestational age. Although a wide array of congenital malformations has been found in animal experimentation after such exposure to x rays, in humans only small head size (exposure at 4-17 wk) and mental retardation (exposure primarily at 8-15 wk) have been observed. In Hiroshima, small head size occurred after doses of 0.10-0.19 Gy or more, and an excess of mental retardation at 0.2-0.4 Gy or more. Intelligence test scores were reduced among A-bomb survivors exposed at 8-15 wk of gestational age by 21-29 IQ points per Gy. Other effects of in-utero exposure to atomic radiation include long-lasting complex chromosome abnormalities

  14. Effects of prenatal exposure to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.W. (National Cancer Institute, Bethesda, MD (USA))

    1990-07-01

    Prenatal exposure to ionizing radiation induces some effects that are seen at birth and others that cannot be detected until later in life. Data from A-bomb survivors in Hiroshima and Nagasaki show a diminished number of births after exposure under 4 wk of gestational age. Although a wide array of congenital malformations has been found in animal experimentation after such exposure to x rays, in humans only small head size (exposure at 4-17 wk) and mental retardation (exposure primarily at 8-15 wk) have been observed. In Hiroshima, small head size occurred after doses of 0.10-0.19 Gy or more, and an excess of mental retardation at 0.2-0.4 Gy or more. Intelligence test scores were reduced among A-bomb survivors exposed at 8-15 wk of gestational age by 21-29 IQ points per Gy. Other effects of in-utero exposure to atomic radiation include long-lasting complex chromosome abnormalities.

  15. Medical exposures requirements, present situation and prospects

    International Nuclear Information System (INIS)

    Cardenas Herrera, Juan

    2012-01-01

    Scope of medical exposures is studied, these include: exposure to patients as part of their diagnosis or treatment, exposures to persons who knowingly have assisted patients, exposures volunteers included in biomedical research programs. Medical exposures have contributed their benefits for human health improvement: possess a necessary character that people have to be exposed to radiation doses to achieve their goals, convergence of risk and benefit in the same individual is presented, variability is implicated in dose given to patients in terms of size and distribution, have contributed significantly to the doses received by the world population. Despite the above attributes and generally contribute to the direct benefit of the patient, long has been given less attention than other forms of exposure, there still potential for dose reduction to patients as a result of the applications of ionizing radiation. Currently have used for nuclear medicine diagnostic x-ray procedures, exams MN, radiotherapy, tomography, both medical and dental radiology. (author) [es

  16. Occupational standard for exposure to ultraviolet radiation (1989)

    International Nuclear Information System (INIS)

    1989-12-01

    The exposure limit (EL) values in this standard refer to ultraviolet radiation (UVR) in the spectral region between 180 and 400 nm and represents conditions under which it is believed that nearly all workers may be repeatedly exposed without adverse effect. The EL values for exposure of the eye or the skin may be used to evaluate potentially hazardous exposure from UVR. The limits do not apply to ultraviolet lasers. The values should be used as guides in the control of exposure to both pulsed and continuous sources of UVR where the exposure duration is not less than 0.1 μsec. The ELs are below levels used for UV exposures of patients as a part of medical treatment or for elective cosmetic purposes. They are intended as upper limits for non therapeutic and non cosmetic exposure. 2 refs., 2 tabs

  17. Foreign Exchange Exposures of Korean Firms

    Directory of Open Access Journals (Sweden)

    Sungbin Cho

    2011-03-01

    Full Text Available We measure foreign exchange exposures as sensitivity of firm's value to FX premium in the CAPM plus FX premium model, and try to find determinants of the exposures; using data of non-financial companies listed in the Korea Exchange from the year 2007 to 2008. Main findings are as follows. If Korean won depreciates, only a small number of firms is benefitted while majority of firms are harmed to the contrary of common knowledge. As a firm's export increases, the foreign exchange exposure increases up to a certain level and after that it declines. And, smaller firms of negative foreign exchange exposures are more sensitive to foreign exchange changes. These suggest heterogeneous effects of foreign exchange rates on industries and firms.

  18. Tetrachloroethylene exposure and bladder cancer risk

    DEFF Research Database (Denmark)

    Vlaanderen, Jelle; Straif, Kurt; Ruder, Avima

    2014-01-01

    BACKGROUND: In 2012, the International Agency for Research on Cancer classified tetrachloroethylene, used in the production of chemicals and the primary solvent used in dry cleaning, as "probably carcinogenic to humans" based on limited evidence of an increased risk of bladder cancer in dry...... cleaners. OBJECTIVES: We assessed the epidemiological evidence for the association between tetrachloroethylene exposure and bladder cancer from published studies estimating occupational exposure to tetrachloroethylene or in workers in the dry-cleaning industry. METHODS: Random-effects meta-analyses were...... carried out separately for occupational exposure to tetrachloroethylene and employment as a dry cleaner. We qualitatively summarized exposure-response data because of the limited number of studies available. RESULTS: The meta-relative risk (mRR) among tetrachloroethylene-exposed workers was 1.08 (95% CI...

  19. Dose evaluation for external exposure in radiation accidents

    International Nuclear Information System (INIS)

    Maruyama, Takashi

    1989-01-01

    Abnormal exposures including emergency and accidental are categorized into external exposure and internal contamination, although both of these may be associated with external contamination. From a point of view of lifesaving in the abnormal exposures, it is primarily important to evaluate radiation dose of exposed persons as soon as possible. This report reviews the status of early dosimetry in the accidental exposures and discusses the optimum methodology of the early dose determination for external exposures in abnormal exposures. Personal monitors generally give an indication of dose to an exposed person only at a single part of the body. The data obtained from the personal monitors should be interpreted with care and in the light of information about the circumstances of exposure. In most cases, the records of environmental monitors or the survey with area monitors provide valuable information on the radiation fields. In the some cases, the reconstruction of the abnormal exposure is required for the dose evaluation by means of phantom experiments. In the case of neutron exposures, activation products in the body or its components or personnel possession can be useful for the early dosimetry. If the dose received by the whole body is evaluated as being very high, clinical observations and biological investigations may be more important guide to initial medical treatment than the early dosimetry. For the dose evaluation of general public, depending on the size of abnormal exposure, information that could be valuable in the assessment of abnormal exposures will come from the early dose estimates with environmental monitors and radiation survey meters. (author)

  20. Is cumulated pyrethroid exposure associated with prediabetes?

    DEFF Research Database (Denmark)

    Hansen, Martin Rune; Jørs, Erik; Lander, Flemming

    2014-01-01

    was to investigate an association between exposure to pyrethroids and abnormal glucose regulation (prediabetes or diabetes). A cross-sectional study was performed among 116 pesticide sprayers from public vector control programs in Bolivia and 92 nonexposed controls. Pesticide exposure (duration, intensity...... pyrethroids, a significant positive trend was observed between cumulative pesticide exposure (total number of hours sprayed) and adjusted OR of abnormal glucose regulation, with OR 14.7 [0.9-235] in the third exposure quintile. The study found a severely increased prevalence of prediabetes among Bolivian...