Evaluation of three physiologically based pharmacokinetic (PBPK) modeling tools for emergency risk assessment after acute dichloromethane exposure

NARCIS (Netherlands)

Boerleider, R. Z.; Olie, J. D N; van Eijkeren, J. C H; Bos, P. M J; Hof, B. G H; de Vries, I.; Bessems, J. G M; Meulenbelt, J.; Hunault, C. C.

2015-01-01

Introduction: Physiologically based pharmacokinetic (PBPK) models may be useful in emergency risk assessment, after acute exposure to chemicals, such as dichloromethane (DCM). We evaluated the applicability of three PBPK models for human risk assessment following a single exposure to DCM: one model

Multimedia radionuclide exposure assessment modeling. Annual report, October 1980-September 1981

International Nuclear Information System (INIS)

Whelan, G.; Onishi, Y.; Simmons, C.S.; Horst, T.W.; Gupta, S.K.; Orgill, M.M.; Newbill, C.A.

1982-12-01

Pacific Northwest Laboratory (PNL) and Los Alamos National Laboratory (LANL) are jointly developing a methodology for assessing exposures of the air, water, and plants to radionuclides as part of an overall development effort of a radionuclide disposal site evaluation methodology. Work in FY-1981 continued the development of the Multimedia Contaminant Environmental Exposure Assessment (MCEA) methodology and initiated an assessment of radionuclide migration in Los Alamos and Pueblo Canyons, New Mexico, using the methodology. The AIRTRAN model was completed, briefly tested, and documented. In addition, a literature search for existing validation data for AIRTRAN was performed. The feasibility and advisability of including the UNSAT moisture flow model as a submodel of the terrestrial code BIOTRAN was assessed. A preliminary application of the proposed MCEA methodology, as it related to the Mortandad-South Mortandad Canyon site in New Mexico is discussed. This preliminary application represented a scaled-down version of the methodology in which only the terrestrial, overland, and surface water components were used. An update describing the progress in the assessment of radionuclide migration in Los Alamos and Pueblo Canyons is presented. 38 references, 47 figures, 11 tables

Annual report, October 1980-September 1981 Multimedia radionuclide exposure assessment modeling.

Energy Technology Data Exchange (ETDEWEB)

Whelan, G.; Onishi, Y.; Simmons, C.S.; Horst, T.W.; Gupta, S.K.; Orgill, M.M.; Newbill, C.A.

1982-12-01

Pacific Northwest Laboratory (PNL) and Los Alamos National Laboratory (LANL) are jointly developing a methodology for assessing exposures of the air, water, and plants to radionuclides as part of an overall development effort of a radionuclide disposal site evaluation methodology. Work in FY-1981 continued the development of the Multimedia Contaminant Environmental Exposure Assessment (MCEA) methodology and initiated an assessment of radionuclide migration in Los Alamos and Pueblo Canyons, New Mexico, using the methodology. The AIRTRAN model was completed, briefly tested, and documented. In addition, a literature search for existing validation data for AIRTRAN was performed. The feasibility and advisability of including the UNSAT moisture flow model as a submodel of the terrestrial code BIOTRAN was assessed. A preliminary application of the proposed MCEA methodology, as it related to the Mortandad-South Mortandad Canyon site in New Mexico is discussed. This preliminary application represented a scaled-down version of the methodology in which only the terrestrial, overland, and surface water components were used. An update describing the progress in the assessment of radionuclide migration in Los Alamos and Pueblo Canyons is presented. 38 references, 47 figures, 11 tables.

Dermal Exposure Assessment to Pesticides in Farming Systems in Developing Countries: Comparison of Models

Directory of Open Access Journals (Sweden)

Camilo Lesmes Fabian

2015-04-01

Full Text Available In the field of occupational hygiene, researchers have been working on developing appropriate methods to estimate human exposure to pesticides in order to assess the risk and therefore to take the due decisions to improve the pesticide management process and reduce the health risks. This paper evaluates dermal exposure models to find the most appropriate. Eight models (i.e., COSHH, DERM, DREAM, EASE, PHED, RISKOFDERM, STOFFENMANAGER and PFAM were evaluated according to a multi-criteria analysis and from these results five models (i.e., DERM, DREAM, PHED, RISKOFDERM and PFAM were selected for the assessment of dermal exposure in the case study of the potato farming system in the Andean highlands of Vereda La Hoya, Colombia. The results show that the models provide different dermal exposure estimations which are not comparable. However, because of the simplicity of the algorithm and the specificity of the determinants, the DERM, DREAM and PFAM models were found to be the most appropriate although their estimations might be more accurate if specific determinants are included for the case studies in developing countries.

An introduction to the indirect exposure assessment approach: modeling human exposure using microenvironmental measurements and the recent National Human Activity Pattern Survey.

Science.gov (United States)

Klepeis, N E

1999-01-01

Indirect exposure approaches offer a feasible and accurate method for estimating population exposures to indoor pollutants, including environmental tobacco smoke (ETS). In an effort to make the indirect exposure assessment approach more accessible to people in the health and risk assessment fields, this paper provides examples using real data from (italic>a(/italic>) a week-long personal carbon monoxide monitoring survey conducted by the author; and (italic>b(/italic>) the 1992 to 1994 National Human Activity Pattern Survey (NHAPS) for the United States. The indirect approach uses measurements of exposures in specific microenvironments (e.g., homes, bars, offices), validated microenvironmental models (based on the mass balance equation), and human activity pattern data obtained from questionnaires to predict frequency distributions of exposure for entire populations. This approach requires fewer resources than the direct approach to exposure assessment, for which the distribution of monitors to a representative sample of a given population is necessary. In the indirect exposure assessment approach, average microenvironmental concentrations are multiplied by the total time spent in each microenvironment to give total integrated exposure. By assuming that the concentrations encountered in each of 10 location categories are the same for different members of the U.S. population (i.e., the NHAPS respondents), the hypothetical contribution that ETS makes to the average 24-hr respirable suspended particle exposure for Americans working their main job is calculated in this paper to be 18 microg/m3. This article is an illustrative review and does not contain an actual exposure assessment or model validation. Images Figure 3 Figure 4 PMID:10350522

Predictive models for the assessment of occupational exposure to chemicals: A new challenge for employers

Directory of Open Access Journals (Sweden)

Jan Piotr Gromiec

2013-10-01

Full Text Available Employers are obliged to carry out and document the risk associated with the use of chemical substances. The best but the most expensive method is to measure workplace concentrations of chemicals. At present no "measureless" method for risk assessment is available in Poland, but predictive models for such assessments have been developed in some countries. The purpose of this work is to review and evaluate the applicability of selected predictive methods for assessing occupational inhalation exposure and related risk to check the compliance with Occupational Exposure Limits (OELs, as well as the compliance with REACH obligations. Based on the literature data HSE COSHH Essentials, EASE, ECETOC TRA, Stoffenmanager, and EMKG-Expo-Tool were evaluated. The data on validation of predictive models were also examined. It seems that predictive models may be used as a useful method for Tier 1 assessment of occupational exposure by inhalation. Since the levels of exposure are frequently overestimated, they should be considered as "rational worst cases" for selection of proper control measures. Bearing in mind that the number of available exposure scenarios and PROC categories is limited, further validation by field surveys is highly recommended. Predictive models may serve as a good tool for preliminary risk assessment and selection of the most appropriate risk control measures in Polish small and medium size enterprises (SMEs providing that they are available in the Polish language. This also requires an extensive training of their future users. Med Pr 2013;64(5:699–716

Health risk assessment of exposure to ionizing radiation

International Nuclear Information System (INIS)

Ogata, Hiromitsu

2011-01-01

Risk assessment is an essential process for evaluating the human health effects of exposure to ionizing radiation and for determining acceptable levels of exposure. There are two major components of radiation risk assessment: a measure of exposure level and a measure of disease occurrence. For quantitative estimation of health risks, it is important to evaluate the association between exposure and disease occurrence using epidemiological or experimental data. In these approaches, statistical risk models are used particularly for estimating cancer risks related to exposure to low levels of radiation. This paper presents a summary of basic models and methods of risk assessment for studying exposure-risk relationships. Moreover, quantitative risk estimates are subject to several sources of uncertainty due to inherent limitations in risk assessment studies. This paper also discusses the limitations of radiation risk assessment. (author)

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.

Generic Screening Models for Assessing Exposures to the Public and ICRP Reference Animals and Plants

Energy Technology Data Exchange (ETDEWEB)

Yankovich, Tamara L.; Proehl, Gerhard; Telleria, Diego [International Atomic Energy Agency, P.O. Box 100, 1400 Vienna (Austria); Berkovskyy, Volodymyr [Ukrainian Radiation Protection Institute (RPI), 53, Melnikova Street, 04050, Kiev (Ukraine)

2014-07-01

With the update of the IAEA Fundamental Safety Principles (SF-1) stating the objective to protect people and the environment from harmful effects of ionizing radiation, it has been necessary to update International Basic Safety Standards (BSS) on Radiation Protection and Safety of Radiation Sources and the underlying safety guides and technical documents to provide guidance on how this could be achieved in practice. The current paper provides an update on the status and plans to revise the IAEA Safety Report 'Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment' (SRS 19) that was published in 2001. The models of SRS 19 (2001), which was focused on assessment of exposures to the public, is being expanded into three volumes that provide methodologies for screening assessments for the public, as well as for flora and fauna. The revised SRS 19 guide will ultimately facilitate the application of screening models for different levels of assessment using updated parameter values from database that have been developed as part of the IAEA's EMRAS (Environmental Modelling for Radiation Safety) and EMRAS II international model validation programmes. The scope of the revised SRS 19 covers prospective screening assessment of doses to the representative person and Reference Animals and Plants (RAPs), and will provide simple and robust assessment methods for radiological assessment related to planning and design, applying a graded approach. Tabulated screening coefficients and environmental dilution factors will be included for 825 radionuclides. The screening coefficients are developed assuming equilibrium conditions; they can be used to assess radiological impacts arising from routine discharges of radionuclides to terrestrial and aquatic receptors for planned exposure situations. Volumes 1 and 2 of the revised SRS 19 are at an advanced stage of completion and are focused on 'Screening Assessment of Public

Kriged and modeled ambient air levels of benzene in an urban environment: an exposure assessment study

Directory of Open Access Journals (Sweden)

Lai Dejian

2011-03-01

Full Text Available Abstract Background There is increasing concern regarding the potential adverse health effects of air pollution, particularly hazardous air pollutants (HAPs. However, quantifying exposure to these pollutants is problematic. Objective Our goal was to explore the utility of kriging, a spatial interpolation method, for exposure assessment in epidemiologic studies of HAPs. We used benzene as an example and compared census tract-level kriged predictions to estimates obtained from the 1999 U.S. EPA National Air Toxics Assessment (NATA, Assessment System for Population Exposure Nationwide (ASPEN model. Methods Kriged predictions were generated for 649 census tracts in Harris County, Texas using estimates of annual benzene air concentrations from 17 monitoring sites operating in Harris and surrounding counties from 1998 to 2000. Year 1999 ASPEN modeled estimates were also obtained for each census tract. Spearman rank correlation analyses were performed on the modeled and kriged benzene levels. Weighted kappa statistics were computed to assess agreement between discretized kriged and modeled estimates of ambient air levels of benzene. Results There was modest correlation between the predicted and modeled values across census tracts. Overall, 56.2%, 40.7%, 31.5% and 28.2% of census tracts were classified as having 'low', 'medium-low', 'medium-high' and 'high' ambient air levels of benzene, respectively, comparing predicted and modeled benzene levels. The weighted kappa statistic was 0.26 (95% confidence interval (CI = 0.20, 0.31, indicating poor agreement between the two methods. Conclusions There was a lack of concordance between predicted and modeled ambient air levels of benzene. Applying methods of spatial interpolation for assessing exposure to ambient air pollutants in health effect studies is hindered by the placement and number of existing stationary monitors collecting HAP data. Routine monitoring needs to be expanded if we are to use these data

An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios (Final Report, 2008)

Science.gov (United States)

EPA announced the availability of the final report, An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios. This report investigates the potential dioxin exposure to artists/hobbyists who use ball clay to make pottery and related products. Derm...

Assessment of predictive dermal exposure to chemicals in the work environment

Directory of Open Access Journals (Sweden)

Agnieszka Jankowska

2017-08-01

Full Text Available Assessment of dermal exposure to chemicals in the work environment is problematic, mainly as a result of the lack of measurement data on occupational exposure to chemicals. Due to common prevalence of occupational skin exposure and its health consequences it is necessary to look for efficient solutions allowing for reliable exposure assessment. The aim of the study is to present predictive models used to assess non-measured dermal exposure, as well as to acquaint Polish users with the principles of the selected model functioning. This paper presents examples of models to assist the employer in the the assessment of occupational exposure associated with the skin contact with chemicals, developed in European Union (EU countries, as well as in countries outside the EU. Based on the literature data dermal exposure models EASE (Estimation and Assessment of Substance Exposure, COSHH Essentials (Control of Substances Hazardous to Health Regulations, DREAM (Dermal Exposure Assessment Method, Stoffenmanager , ECETOC TRA (European Centre for Ecotoxicology and Toxicology of Chemicals Targeted Risk Assessment, MEASE (Metal’s EASE, PHED (Pesticide Handlers Exposure Database, DERM (Dermal Exposure Ranking Method and RISKOFDERM (Risk Assessment of Occupational Dermal Exposure to Chemicals were briefly described. Moreover the characteristics of RISKOFDERM, guidelines for its use, information on input and output data were further detailed. Problem of full work shift dermal exposure assessment is described. An example of exposure assessment using RISKOFDERM and effectiveness evaluation to date were also presented. When no measurements are available, RISKOFDERM allows dermal exposure assessment and thus can improve the risk assessment quality and effectiveness of dermal risk management. Med Pr 2017;68(4:557–569

The Validity and Applicability of Using a Generic Exposure Assessment Model for Occupational Exposure to Nano-Objects and Their Aggregates and Agglomerates

NARCIS (Netherlands)

Bekker, Cindy; Voogd, Eef; Fransman, Wouter; Vermeulen, Roel

2016-01-01

BACKGROUND: Control banding can be used as a first-tier assessment to control worker exposure to nano-objects and their aggregates and agglomerates (NOAA). In a second tier, more advanced modelling approaches are needed to produce quantitative exposure estimates. As currently no general quantitative

The validity and applicability of using a generic exposure assessment model for occupational exposure to nano-objects and their aggregates and agglomerates

NARCIS (Netherlands)

Bekker, C.; Voogd, E.; Fransman, W.; Vermeulen, R.

2016-01-01

Background: Control banding can be used as a first-tier assessment to control worker exposure to nano-objects and their aggregates and agglomerates (NOAA). In a second tier, more advanced modelling approaches are needed to produce quantitative exposure estimates. As currently no general quantitative

Opportunities for using spatial property assessment data in air pollution exposure assessments

Directory of Open Access Journals (Sweden)

Keller C Peter

2005-10-01

Full Text Available Abstract Background Many epidemiological studies examining the relationships between adverse health outcomes and exposure to air pollutants use ambient air pollution measurements as a proxy for personal exposure levels. When pollution levels vary at neighbourhood levels, using ambient pollution data from sparsely located fixed monitors may inadequately capture the spatial variation in ambient pollution. A major constraint to moving toward exposure assessments and epidemiological studies of air pollution at a neighbourhood level is the lack of readily available data at appropriate spatial resolutions. Spatial property assessment data are widely available in North America and may provide an opportunity for developing neighbourhood level air pollution exposure assessments. Results This paper provides a detailed description of spatial property assessment data available in the Pacific Northwest of Canada and the United States, and provides examples of potential applications of spatial property assessment data for improving air pollution exposure assessment at the neighbourhood scale, including: (1 creating variables for use in land use regression modelling of neighbourhood levels of ambient air pollution; (2 enhancing wood smoke exposure estimates by mapping fireplace locations; and (3 using data available on individual building characteristics to produce a regional air pollution infiltration model. Conclusion Spatial property assessment data are an extremely detailed data source at a fine spatial resolution, and therefore a source of information that could improve the quality and spatial resolution of current air pollution exposure assessments.

CAirTOX: A compartment model for assessing the fate of and human exposure to toxic-chemical emissions to air

Energy Technology Data Exchange (ETDEWEB)

McKone, T.E.

1993-10-01

CAirTOX has been developed as a spreadsheet model to assist in making a risk assessment of toxic air emissions. With CAirTOX, one can address how contaminants released to an air basin can lead to contamination of soil, food, surface water, and sediments. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify uncertainty in multimedia, multiple-pathway exposure assessments. The multimedia transport and transformation model is a steady-state, but non-equilibrium model that can be used to assess concentrations of contaminants released continuously to air. In Part 1, the authors describe the multimedia transport and transformation model used to determine the fate of air emissions. In Part 2, they describe inputs and data needs for CAirTOX and the development of a set of landscape factors, which can be used to represent regional air basin/water-shed systems in California. In Part 3, they describe the multiple-pathway exposure scenarios and exposure algorithms. In Part 4, they compare the HRA approach and results and the CAirTOX exposure equations. In Part 5, they consider model sensitivity and uncertainty to determine how variability and uncertainty in model inputs affects the precision, accuracy, and credibility of the model output.

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...

Validity of a traffic air pollutant dispersion model to assess exposure to fine particles.

Science.gov (United States)

Kostrzewa, Aude; Reungoat, Patrice; Raherison, Chantal

2009-08-01

Fine particles (PM(2.5)) are an important component of air pollution. Epidemiological studies have shown health effects due to ambient air particles, particularly allergies in children. Since the main difficulty is to determine exposure to such pollution, traffic air pollutant (TAP) dispersions models have been developed to improve the estimation of individual exposure levels. One such model, the ExTra index, has been validated for nitrogen oxide concentrations but not for other pollutants. The purpose of this study was to assess the validity of the ExTra index to assess PM(2.5) exposure. We compared PM(2.5) concentrations calculated by the ExTra index to reference measures (passive samplers situated under the covered part of the playground), in 15 schools in Bordeaux, in 2000. First, we collected the input data required by the ExTra index: background and local pollution depending on traffic, meteorology and topography. Second, the ExTra index was calculated for each school. Statistical analysis consisted of a graphic description; then, we calculated an intraclass correlation coefficient. Concentrations calculated with the ExTra index and the reference method were similar. The ExTra index underestimated exposure by 2.2 microg m(-3) on average compared to the reference method. The intraclass correlation coefficient was 0.85 and its 95% confidence interval was [0.62; 0.95]. The results suggest that the ExTra index provides an assessment of PM(2.5) exposure similar to that of the reference method. Although caution is required in interpreting these results owing to the small number of sites, the ExTra index could be a useful epidemiological tool for reconstructing individual exposure, an important challenge in epidemiology.

Perspectives for integrating human and environmental exposure assessments.

Science.gov (United States)

Ciffroy, P; Péry, A R R; Roth, N

2016-10-15

Integrated Risk Assessment (IRA) has been defined by the EU FP7 HEROIC Coordination action as "the mutual exploitation of Environmental Risk Assessment for Human Health Risk Assessment and vice versa in order to coherently and more efficiently characterize an overall risk to humans and the environment for better informing the risk analysis process" (Wilks et al., 2015). Since exposure assessment and hazard characterization are the pillars of risk assessment, integrating Environmental Exposure assessment (EEA) and Human Exposure assessment (HEA) is a major component of an IRA framework. EEA and HEA typically pursue different targets, protection goals and timeframe. However, human and wildlife species also share the same environment and they similarly inhale air and ingest water and food through often similar overlapping pathways of exposure. Fate models used in EEA and HEA to predict the chemicals distribution among physical and biological media are essentially based on common properties of chemicals, and internal concentration estimations are largely based on inter-species (i.e. biota-to-human) extrapolations. Also, both EEA and HEA are challenged by increasing scientific complexity and resources constraints. Altogether, these points create the need for a better exploitation of all currently existing data, experimental approaches and modeling tools and it is assumed that a more integrated approach of both EEA and HEA may be part of the solution. Based on the outcome of an Expert Workshop on Extrapolations in Integrated Exposure Assessment organized by the HEROIC project in January 2014, this paper identifies perspectives and recommendations to better harmonize and extrapolate exposure assessment data, models and methods between Human Health and Environmental Risk Assessments to support the further development and promotion of the concept of IRA. Ultimately, these recommendations may feed into guidance showing when and how to apply IRA in the regulatory decision

Assessing exposure to violence using multiple informants: application of hierarchical linear model.

Science.gov (United States)

Kuo, M; Mohler, B; Raudenbush, S L; Earls, F J

2000-11-01

The present study assesses the effects of demographic risk factors on children's exposure to violence (ETV) and how these effects vary by informants. Data on exposure to violence of 9-, 12-, and 15-year-olds were collected from both child participants (N = 1880) and parents (N = 1776), as part of the assessment of the Project on Human Development in Chicago Neighborhoods (PHDCN). A two-level hierarchical linear model (HLM) with multivariate outcomes was employed to analyze information obtained from these two different groups of informants. The findings indicate that parents generally report less ETV than do their children and that associations of age, gender, and parent education with ETV are stronger in the self-reports than in the parent reports. The findings support a multivariate approach when information obtained from different sources is being integrated. The application of HLM allows an assessment of interactions between risk factors and informants and uses all available data, including data from one informant when data from the other informant is missing.

A PROBABILISTIC EXPOSURE ASSESSMENT FOR CHILDREN WHO CONTACT CCA-TREATED PLAYSETS AND DECKS USING THE STOCHASTIC HUMAN EXPOSURE AND DOSE SIMULATION (SHEDS) MODEL FOR THE WOOD PRESERVATIVE EXPOSURE SCENARIO

Science.gov (United States)

The U.S. Environmental Protection Agency has conducted a probabilistic exposure and dose assessment on the arsenic (As) and chromium (Cr) components of Chromated Copper Arsenate (CCA) using the Stochastic Human Exposure and Dose Simulation model for wood preservatives (SHEDS-Wood...

Modeling The Inhalation Exposure Pathway In Performance Assessment Of Geologic Radioactive Waste Repository At Yucca Mountain

International Nuclear Information System (INIS)

M.A. Wasiolek

2006-01-01

Inhalation exposure pathway modeling has recently been investigated as one of the tasks of the BIOPROTA Project (BIOPROTA 2005). BIOPROTA was set up to address the key uncertainties in long term assessments of contaminant releases into the environment arising from radioactive waste disposal. Participants of this international Project include national authorities and agencies, both regulators and operators, with responsibility for achieving safe and acceptable radioactive waste management. The objective of the inhalation task was to investigate the calculation of doses arising from inhalation of particles suspended from soils within which long-lived radionuclides, particularly alpha emitters, had accumulated. It was recognized that site-specific conditions influence the choice of conceptual model and input parameter values. Therefore, one of the goals of the task was to identify the circumstances in which different processes included in specific inhalation exposure pathway models were important. This paper discusses evaluation of processes and modeling assumptions specific to the proposed repository at Yucca Mountain as compared to the typical approaches and other models developed for different assessments and project specific contexts. Inhalation of suspended particulates that originate from contaminated soil is an important exposure pathway, particularly for exposure to actinides such as uranium, neptunium and plutonium. Radionuclide accumulation in surface soil arises from irrigation of soil with contaminated water over many years. The level of radionuclide concentration in surface soil depends on the assumed duration of irrigation. Irrigation duration is one of the parameters used on biosphere models and it depends on a specific assessment context. It is one of the parameters addressed in this paper from the point of view of assessment context for the proposed repository at Yucca Mountain. The preferred model for the assessment of inhalation exposure uses

Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment

Science.gov (United States)

Diao, Y. L.; Sun, W. N.; He, Y. Q.; Leung, S. W.; Siu, Y. M.

2017-10-01

In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort—the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.

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

Bayesian algorithm implementation in a real time exposure assessment model on benzene with calculation of associated cancer risks.

Science.gov (United States)

Sarigiannis, Dimosthenis A; Karakitsios, Spyros P; Gotti, Alberto; Papaloukas, Costas L; Kassomenos, Pavlos A; Pilidis, Georgios A

2009-01-01

The objective of the current study was the development of a reliable modeling platform to calculate in real time the personal exposure and the associated health risk for filling station employees evaluating current environmental parameters (traffic, meteorological and amount of fuel traded) determined by the appropriate sensor network. A set of Artificial Neural Networks (ANNs) was developed to predict benzene exposure pattern for the filling station employees. Furthermore, a Physiology Based Pharmaco-Kinetic (PBPK) risk assessment model was developed in order to calculate the lifetime probability distribution of leukemia to the employees, fed by data obtained by the ANN model. Bayesian algorithm was involved in crucial points of both model sub compartments. The application was evaluated in two filling stations (one urban and one rural). Among several algorithms available for the development of the ANN exposure model, Bayesian regularization provided the best results and seemed to be a promising technique for prediction of the exposure pattern of that occupational population group. On assessing the estimated leukemia risk under the scope of providing a distribution curve based on the exposure levels and the different susceptibility of the population, the Bayesian algorithm was a prerequisite of the Monte Carlo approach, which is integrated in the PBPK-based risk model. In conclusion, the modeling system described herein is capable of exploiting the information collected by the environmental sensors in order to estimate in real time the personal exposure and the resulting health risk for employees of gasoline filling stations.

Indirect human exposure assessment of airborne lead deposited on soil via a simplified fate and speciation modelling approach.

Science.gov (United States)

Pizzol, Massimo; Bulle, Cécile; Thomsen, Marianne

2012-04-01

In order to estimate the total exposure to the lead emissions from a municipal waste combustion plant in Denmark, the indirect pathway via ingestion of lead deposited on soil has to be quantified. Multi-media fate models developed for both Risk Assessment (RA) and Life Cycle Assessment (LCA) can be used for this purpose, but present high uncertainties in the assessment of metal's fate. More sophisticated and metal-specific geochemical models exist, that could lower the uncertainties by e.g. accounting for metal speciation, but they require a large amount of data and are unpractical to combine broadly with other fate and dispersion models. In this study, a Simplified Fate & Speciation Model (SFSM) is presented, that is based on the parsimony principle: "as simple as possible, as complex as needed", and that can be used for indirect human exposure assessment in different context like RA and regionalized LCA. SFSM couples traditional multi-media mass balances with empirical speciation models in a tool that has a simple theoretical framework and that is not data-intensive. The model calculates total concentration, dissolved concentration, and free ion activity of Cd, Cu, Ni, Pb and Zn in different soil layers, after accounting for metal deposition and dispersion. The model is tested for these five metals by using data from peer reviewed literature. Results show good accordance between measured and calculated values (factor of 3). The model is used to predict the human exposure via soil to lead initially emitted into air by the waste combustion plant and both the lead cumulative exposure and intake fraction are calculated. Copyright © 2012 Elsevier B.V. All rights reserved.

Model for screening-level assessment of near-field human exposure to neutral organic chemicals released indoors.

Science.gov (United States)

Zhang, Xianming; Arnot, Jon A; Wania, Frank

2014-10-21

Screening organic chemicals for hazard and risk to human health requires near-field human exposure models that can be readily parametrized with available data. The integration of a model of human exposure, uptake, and bioaccumulation into an indoor mass balance model provides a quantitative framework linking emissions in indoor environments with human intake rates (iRs), intake fractions (iFs) and steady-state concentrations in humans (C) through consideration of dermal permeation, inhalation, and nondietary ingestion exposure pathways. Parameterized based on representative indoor and adult human characteristics, the model is applied here to 40 chemicals of relevance in the context of human exposure assessment. Intake fractions and human concentrations (C(U)) calculated with the model based on a unit emission rate to air for these 40 chemicals span 2 and 5 orders of magnitude, respectively. Differences in priority ranking based on either iF or C(U) can be attributed to the absorption, biotransformation and elimination processes within the human body. The model is further applied to a large data set of hypothetical chemicals representative of many in-use chemicals to show how the dominant exposure pathways, iF and C(U) change as a function of chemical properties and to illustrate the capacity of the model for high-throughput screening. These simulations provide hypotheses for the combination of chemical properties that may result in high exposure and internal dose. The model is further exploited to highlight the role human contaminant uptake plays in the overall fate of certain chemicals indoors and consequently human exposure.

Bayesian Algorithm Implementation in a Real Time Exposure Assessment Model on Benzene with Calculation of Associated Cancer Risks

Directory of Open Access Journals (Sweden)

Pavlos A. Kassomenos

2009-02-01

Full Text Available The objective of the current study was the development of a reliable modeling platform to calculate in real time the personal exposure and the associated health risk for filling station employees evaluating current environmental parameters (traffic, meteorological and amount of fuel traded determined by the appropriate sensor network. A set of Artificial Neural Networks (ANNs was developed to predict benzene exposure pattern for the filling station employees. Furthermore, a Physiology Based Pharmaco-Kinetic (PBPK risk assessment model was developed in order to calculate the lifetime probability distribution of leukemia to the employees, fed by data obtained by the ANN model. Bayesian algorithm was involved in crucial points of both model sub compartments. The application was evaluated in two filling stations (one urban and one rural. Among several algorithms available for the development of the ANN exposure model, Bayesian regularization provided the best results and seemed to be a promising technique for prediction of the exposure pattern of that occupational population group. On assessing the estimated leukemia risk under the scope of providing a distribution curve based on the exposure levels and the different susceptibility of the population, the Bayesian algorithm was a prerequisite of the Monte Carlo approach, which is integrated in the PBPK-based risk model. In conclusion, the modeling system described herein is capable of exploiting the information collected by the environmental sensors in order to estimate in real time the personal exposure and the resulting health risk for employees of gasoline filling stations.

Assessment and improvement of biotransfer models to cow’s milk and beef used in exposure assessment tools for organic pollutants

OpenAIRE

Takaki, Koki; Wade, Andrew J.; Collins, Christopher D.

2015-01-01

The aim of this study was to assess and improve the accuracy of biotransfer models for the organic pollutants (PCBs, PCDD/Fs, PBDEs, PFCAs, and pesticides) into cow’s milk and beef used in human exposure assessment. Metabolic rate in cattle is known as a key parameter for this biotransfer, however few experimental data and no simulation methods are currently available. In this research, metabolic rate was estimated using existing QSAR biodegradation models of microorganisms (BioWIN) and fish ...

76 FR 365 - Exposure Modeling Public Meeting

Science.gov (United States)

2011-01-04

... classification for ecological risk assessments using aerial photography and GIS data. Dermal contact, movement... ENVIRONMENTAL PROTECTION AGENCY [EPA-HQ-OPP-2009-0879; FRL-8860-5] Exposure Modeling Public Meeting AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: An Exposure Modeling...

Assessment of risk of potential exposures on facilities industries

International Nuclear Information System (INIS)

Leocadio, Joao Carlos

2007-03-01

This work develops a model to evaluate potential exposures on open facilities of industrial radiography in Brazil. This model will decisively contribute to optimize operational, radiological protection and safety procedures, to prevent radiation accidents and to reduce human errors in industrial radiography. The probabilistic safety assessment (PSA) methodology was very useful to assess potential exposures. The open facilities of industrial radiography were identified as the scenario to be analyzed in what concerns the evaluation of potential exposures, due to their high accidents indices. The results of the assessment of potential exposures confirm that the industrial radiography in Brazil is a high-risk practice as classified by the IAEA. The risk of potential exposure was estimated to be 40,5 x 10 -2 per year in Brazil, having as main consequences injuries to the workers' hands and arms. In the world scene, the consequences are worst, leading to fatalities of people, thus emphasizing the high risk of industrial radiography. (author)

Risk assessment and management of radiofrequency radiation exposure

Energy Technology Data Exchange (ETDEWEB)

Dabala, Dana [Railways Medical Clinic Cluj-Napoca, Occupational Medicine Department, 16-20 Bilascu Gheorghe St., 400015 Cluj-Napoca (Romania); Surducan, Emanoil; Surducan, Vasile; Neamtu, Camelia [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath St., 400293 Cluj-Napoca (Romania)

2013-11-13

Radiofrequency radiation (RFR) industry managers, occupational physicians, security department, and other practitioners must be advised on the basic of biophysics and the health effects of RF electromagnetic fields so as to guide the management of exposure. Information on biophysics of RFR and biological/heath effects is derived from standard texts, literature and clinical experiences. Emergency treatment and ongoing care is outlined, with clinical approach integrating the circumstances of exposure and the patient's symptoms. Experimental risk assessment model in RFR chronic exposure is proposed. Planning for assessment and monitoring exposure, ongoing care, safety measures and work protection are outlining the proper management.

Risk assessment and management of radiofrequency radiation exposure

International Nuclear Information System (INIS)

Dabala, Dana; Surducan, Emanoil; Surducan, Vasile; Neamtu, Camelia

2013-01-01

Radiofrequency radiation (RFR) industry managers, occupational physicians, security department, and other practitioners must be advised on the basic of biophysics and the health effects of RF electromagnetic fields so as to guide the management of exposure. Information on biophysics of RFR and biological/heath effects is derived from standard texts, literature and clinical experiences. Emergency treatment and ongoing care is outlined, with clinical approach integrating the circumstances of exposure and the patient's symptoms. Experimental risk assessment model in RFR chronic exposure is proposed. Planning for assessment and monitoring exposure, ongoing care, safety measures and work protection are outlining the proper management

Environmental fate and exposure models: advances and challenges in 21st century chemical risk assessment.

Science.gov (United States)

Di Guardo, Antonio; Gouin, Todd; MacLeod, Matthew; Scheringer, Martin

2018-01-24

Environmental fate and exposure models are a powerful means to integrate information on chemicals, their partitioning and degradation behaviour, the environmental scenario and the emissions in order to compile a picture of chemical distribution and fluxes in the multimedia environment. A 1995 pioneering book, resulting from a series of workshops among model developers and users, reported the main advantages and identified needs for research in the field of multimedia fate models. Considerable efforts were devoted to their improvement in the past 25 years and many aspects were refined; notably the inclusion of nanomaterials among the modelled substances, the development of models at different spatial and temporal scales, the estimation of chemical properties and emission data, the incorporation of additional environmental media and processes, the integration of sensitivity and uncertainty analysis in the simulations. However, some challenging issues remain and require research efforts and attention: the need of methods to estimate partition coefficients for polar and ionizable chemical in the environment, a better description of bioavailability in different environments as well as the requirement of injecting more ecological realism in exposure predictions to account for the diversity of ecosystem structures and functions in risk assessment. Finally, to transfer new scientific developments into the realm of regulatory risk assessment, we propose the formation of expert groups that compare, discuss and recommend model modifications and updates and help develop practical tools for risk assessment.

An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios (External Review Draft)

Science.gov (United States)

EPA has released an external review draft entitled, An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios(External Review Draft). The public comment period and the external peer-review workshop are separate processes that provide opportunities ...

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

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

Probabilistic assessment of wildfire hazard and municipal watershed exposure

Science.gov (United States)

Joe Scott; Don Helmbrecht; Matthew P. Thompson; David E. Calkin; Kate Marcille

2012-01-01

The occurrence of wildfires within municipal watersheds can result in significant impacts to water quality and ultimately human health and safety. In this paper, we illustrate the application of geospatial analysis and burn probability modeling to assess the exposure of municipal watersheds to wildfire. Our assessment of wildfire exposure consists of two primary...

From eyeballing to statistical modelling : methods for assessment of occupational exposure

NARCIS (Netherlands)

Kromhout, H.

1994-01-01

In this thesis methods for assessment of occupational exposure are evaluated and developed. These methods range from subjective methods (qualitative and semiquantitative) to more objective quantitative methods based on actual measurement of personal exposure to chemical and physical

Applicability of western chemical dietary exposure models to the Chinese population.

Science.gov (United States)

Zhao, Shizhen; Price, Oliver; Liu, Zhengtao; Jones, Kevin C; Sweetman, Andrew J

2015-07-01

A range of exposure models, which have been developed in Europe and North America, are playing an increasingly important role in priority setting and the risk assessment of chemicals. However, the applicability of these tools, which are based on Western dietary exposure pathways, to estimate chemical exposure to the Chinese population to support the development of a risk-based environment and exposure assessment, is unclear. Three frequently used modelling tools, EUSES, RAIDAR and ACC-HUMANsteady, have been evaluated in terms of human dietary exposure estimation by application to a range of chemicals with different physicochemical properties under both model default and Chinese dietary scenarios. Hence, the modelling approaches were assessed by considering dietary pattern differences only. The predicted dietary exposure pathways were compared under both scenarios using a range of hypothetical and current emerging contaminants. Although the differences across models are greater than those between dietary scenarios, model predictions indicated that dietary preference can have a significant impact on human exposure, with the relatively high consumption of vegetables and cereals resulting in higher exposure via plants-based foodstuffs under Chinese consumption patterns compared to Western diets. The selected models demonstrated a good ability to identify key dietary exposure pathways which can be used for screening purposes and an evaluative risk assessment. However, some model adaptations will be required to cover a number of important Chinese exposure pathways, such as freshwater farmed-fish, grains and pork. Copyright © 2015 Elsevier Inc. All rights reserved.

Exposure assessment of process-related contaminants in food by biomarker monitoring.

Science.gov (United States)

Rietjens, Ivonne M C M; Dussort, P; Günther, Helmut; Hanlon, Paul; Honda, Hiroshi; Mally, Angela; O'Hagan, Sue; Scholz, Gabriele; Seidel, Albrecht; Swenberg, James; Teeguarden, Justin; Eisenbrand, Gerhard

2018-01-01

Exposure assessment is a fundamental part of the risk assessment paradigm, but can often present a number of challenges and uncertainties. This is especially the case for process contaminants formed during the processing, e.g. heating of food, since they are in part highly reactive and/or volatile, thus making exposure assessment by analysing contents in food unreliable. New approaches are therefore required to accurately assess consumer exposure and thus better inform the risk assessment. Such novel approaches may include the use of biomarkers, physiologically based kinetic (PBK) modelling-facilitated reverse dosimetry, and/or duplicate diet studies. This review focuses on the state of the art with respect to the use of biomarkers of exposure for the process contaminants acrylamide, 3-MCPD esters, glycidyl esters, furan and acrolein. From the overview presented, it becomes clear that the field of assessing human exposure to process-related contaminants in food by biomarker monitoring is promising and strongly developing. The current state of the art as well as the existing data gaps and challenges for the future were defined. They include (1) using PBK modelling and duplicate diet studies to establish, preferably in humans, correlations between external exposure and biomarkers; (2) elucidation of the possible endogenous formation of the process-related contaminants and the resulting biomarker levels; (3) the influence of inter-individual variations and how to include that in the biomarker-based exposure predictions; (4) the correction for confounding factors; (5) the value of the different biomarkers in relation to exposure scenario's and risk assessment, and (6) the possibilities of novel methodologies. In spite of these challenges it can be concluded that biomarker-based exposure assessment provides a unique opportunity to more accurately assess consumer exposure to process-related contaminants in food and thus to better inform risk assessment.

Exposure assessment of mobile phone base station radiation in an outdoor environment using sequential surrogate modeling.

Science.gov (United States)

Aerts, Sam; Deschrijver, Dirk; Joseph, Wout; Verloock, Leen; Goeminne, Francis; Martens, Luc; Dhaene, Tom

2013-05-01

Human exposure to background radiofrequency electromagnetic fields (RF-EMF) has been increasing with the introduction of new technologies. There is a definite need for the quantification of RF-EMF exposure but a robust exposure assessment is not yet possible, mainly due to the lack of a fast and efficient measurement procedure. In this article, a new procedure is proposed for accurately mapping the exposure to base station radiation in an outdoor environment based on surrogate modeling and sequential design, an entirely new approach in the domain of dosimetry for human RF exposure. We tested our procedure in an urban area of about 0.04 km(2) for Global System for Mobile Communications (GSM) technology at 900 MHz (GSM900) using a personal exposimeter. Fifty measurement locations were sufficient to obtain a coarse street exposure map, locating regions of high and low exposure; 70 measurement locations were sufficient to characterize the electric field distribution in the area and build an accurate predictive interpolation model. Hence, accurate GSM900 downlink outdoor exposure maps (for use in, e.g., governmental risk communication and epidemiological studies) are developed by combining the proven efficiency of sequential design with the speed of exposimeter measurements and their ease of handling. Copyright © 2013 Wiley Periodicals, Inc.

Ecological models and pesticide risk assessment: current modeling practice.

Science.gov (United States)

Schmolke, Amelie; Thorbek, Pernille; Chapman, Peter; Grimm, Volker

2010-04-01

Ecological risk assessments of pesticides usually focus on risk at the level of individuals, and are carried out by comparing exposure and toxicological endpoints. However, in most cases the protection goal is populations rather than individuals. On the population level, effects of pesticides depend not only on exposure and toxicity, but also on factors such as life history characteristics, population structure, timing of application, presence of refuges in time and space, and landscape structure. Ecological models can integrate such factors and have the potential to become important tools for the prediction of population-level effects of exposure to pesticides, thus allowing extrapolations, for example, from laboratory to field. Indeed, a broad range of ecological models have been applied to chemical risk assessment in the scientific literature, but so far such models have only rarely been used to support regulatory risk assessments of pesticides. To better understand the reasons for this situation, the current modeling practice in this field was assessed in the present study. The scientific literature was searched for relevant models and assessed according to nine characteristics: model type, model complexity, toxicity measure, exposure pattern, other factors, taxonomic group, risk assessment endpoint, parameterization, and model evaluation. The present study found that, although most models were of a high scientific standard, many of them would need modification before they are suitable for regulatory risk assessments. The main shortcomings of currently available models in the context of regulatory pesticide risk assessments were identified. When ecological models are applied to regulatory risk assessments, we recommend reviewing these models according to the nine characteristics evaluated here. (c) 2010 SETAC.

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.

Framework for Multi-Pathway Cumulative Exposure for Comparative Assessments

DEFF Research Database (Denmark)

McKone, Tom; Fantke, Peter

2016-01-01

in comparative risk assessment, life-cycle assessment (LCA), and chemical alternatives assessment (CAA), multimedia fate and exposure models synthesize information about partitioning, reaction, and intermedia-transport properties of chemicals in a representative (local to regional) or generic (continental...

Harmonizing exposure metrics and methods for sustainability assessments of food contact materials

DEFF Research Database (Denmark)

Ernstoff, Alexi; Jolliet, Olivier; Niero, Monia

2016-01-01

) and Cradle to Cradle to support packaging design. Each assessment has distinct context and goals, but can help manage exposure to toxic chemicals and other environmental impacts. Metrics a nd methods to quantify and characterize exposure to potentially toxic chemicals specifically in food packaging are......, however, notably lacking from such assessments. Furthermore, previous case studies demonstrated that sustainable packaging design focuses, such as decreasing greenhouse gas emissions or resource consumption, can increase exposure to toxic chemicals through packaging. Thereby, developing harmonized methods...... for quantifying exposure to chemicals in food packaging is critical to ensure ‘sustainable packages’ do not increase exposure to toxic chemicals. Therefore we developed modelling methods suitable for first-tier risk screening and environmental assessments. The modelling framework was based on the new product...

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...

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.

Assessment of dermal exposure to chemicals

NARCIS (Netherlands)

Hemmen, J.J. van; Brouwer, D.H.

1995-01-01

The methods for the dermal exposure assessment vary in their complexity and are in some sense complementary to each other. The most easy-to-use methods involve a pseudo-skin-approach, such as gloves and removal by washing. In some cases generic modelling appears to be possible. The experimental

Development of Toxicological Risk Assessment Models for Acute and Chronic Exposure to Pollutants

Directory of Open Access Journals (Sweden)

Elke S. Reichwaldt

2016-08-01

Full Text Available Alert level frameworks advise agencies on a sequence of monitoring and management actions, and are implemented so as to reduce the risk of the public coming into contact with hazardous substances. Their effectiveness relies on the detection of the hazard, but with many systems not receiving any regular monitoring, pollution events often go undetected. We developed toxicological risk assessment models for acute and chronic exposure to pollutants that incorporate the probabilities that the public will come into contact with undetected pollution events, to identify the level of risk a system poses in regards to the pollutant. As a proof of concept, we successfully demonstrated that the models could be applied to determine probabilities of acute and chronic illness types related to recreational activities in waterbodies containing cyanotoxins. Using the acute model, we identified lakes that present a ‘high’ risk to develop Day Away From Work illness, and lakes that present a ‘low’ or ‘medium’ risk to develop First Aid Cases when used for swimming. The developed risk models succeeded in categorising lakes according to their risk level to the public in an objective way. Modelling by how much the probability of public exposure has to decrease to lower the risks to acceptable levels will enable authorities to identify suitable control measures and monitoring strategies. We suggest broadening the application of these models to other contaminants.

Comparative Assessment of Particulate Air Pollution Exposure from Municipal Solid Waste Incinerator Emissions

Science.gov (United States)

Ashworth, Danielle C.; Fuller, Gary W.; Toledano, Mireille B.; Font, Anna; Elliott, Paul; Hansell, Anna L.; de Hoogh, Kees

2013-01-01

Background. Research to date on health effects associated with incineration has found limited evidence of health risks, but many previous studies have been constrained by poor exposure assessment. This paper provides a comparative assessment of atmospheric dispersion modelling and distance from source (a commonly used proxy for exposure) as exposure assessment methods for pollutants released from incinerators. Methods. Distance from source and the atmospheric dispersion model ADMS-Urban were used to characterise ambient exposures to particulates from two municipal solid waste incinerators (MSWIs) in the UK. Additionally an exploration of the sensitivity of the dispersion model simulations to input parameters was performed. Results. The model output indicated extremely low ground level concentrations of PM10, with maximum concentrations of incinerator characteristics, magnitude of emissions, and surrounding meteorological and topographical conditions are considered. Reducing exposure misclassification is particularly important in environmental epidemiology to aid detection of low-level risks. PMID:23935644

Exposure assessment of dioxins and dioxin-like PCBs in pasteurised bovine milk using probabilistic modelling.

Science.gov (United States)

Adekunte, Adefunke O; Tiwari, Brijesh K; O'Donnell, Colm P

2010-09-01

Quantitative exposure assessment is a useful technique to investigate the risk from contaminants in the food chain. The objective of this study was to develop a probabilistic exposure assessment model for dioxins (PCDD/Fs) and dioxin-like PCBs (DL-PCBs) in pasteurised bovine milk. Mean dioxins and DL-PCBs (non-ortho and mono-ortho PCBs) concentrations (pg WHO-TEQ g(-1)) in bovine milk were estimated as 0.06 ± 0.07 pg WHO-TEQ g(-1) for dioxins and 0.08 ± 0.07 pg WHO-TEQ g(-1) for DL-PCBs using Monte Carlo simulation. The simulated model estimated mean exposure for dioxins was 0.19 ± 0.29 pg WHO-TEQ kg(-1)bw d(-1) and 0.14 ± 0.22 pg WHO-TEQ kg(-1) bw d(-1) and for DL-PCBs was 0.25 ± 0.30 pg WHO-TEQ kg(-1) bw d(-1) and 0.19 ± 0.22 pg WHO-TEQ kg(-1) bw d(-1) for men and women, respectively. This study showed that the mean dioxins and DL-PCBs exposure from consumption of pasteurised bovine milk is below the provisional maximum tolerable monthly intake of 70 pg TEQ kg(-1) bw month(-1) (equivalent of 2.3 pg TEQ kg(-1) bw d(-1)) recommended by the Joint FAO/WHO Expert Committee on Food Additives and Contaminants (JECFA). Results from this study also showed that the estimated dioxins and DL-PCBs concentration in pasteurised bovine milk is comparable to those reported in previous studies. Copyright © 2010 Elsevier Ltd. All rights reserved.

A study on modeling nitrogen dioxide concentrations using land-use regression and conventionally used exposure assessment methods

Science.gov (United States)

Choi, Giehae; Bell, Michelle L.; Lee, Jong-Tae

2017-04-01

The land-use regression (LUR) approach to estimate the levels of ambient air pollutants is becoming popular due to its high validity in predicting small-area variations. However, only a few studies have been conducted in Asian countries, and much less research has been conducted on comparing the performances and applied estimates of different exposure assessments including LUR. The main objectives of the current study were to conduct nitrogen dioxide (NO2) exposure assessment with four methods including LUR in the Republic of Korea, to compare the model performances, and to estimate the empirical NO2 exposures of a cohort. The study population was defined as the year 2010 participants of a government-supported cohort established for bio-monitoring in Ulsan, Republic of Korea. The annual ambient NO2 exposures of the 969 study participants were estimated with LUR, nearest station, inverse distance weighting, and ordinary kriging. Modeling was based on the annual NO2 average, traffic-related data, land-use data, and altitude of the 13 regularly monitored stations. The final LUR model indicated that area of transportation, distance to residential area, and area of wetland were important predictors of NO2. The LUR model explained 85.8% of the variation observed in the 13 monitoring stations of the year 2009. The LUR model outperformed the others based on leave-one out cross-validation comparing the correlations and root-mean square error. All NO2 estimates ranged from 11.3-18.0 ppb, with that of LUR having the widest range. The NO2 exposure levels of the residents differed by demographics. However, the average was below the national annual guidelines of the Republic of Korea (30 ppb). The LUR models showed high performances in an industrial city in the Republic of Korea, despite the small sample size and limited data. Our findings suggest that the LUR method may be useful in similar settings in Asian countries where the target region is small and availability of data is

Turbulent eddy diffusion models in exposure assessment - Determination of the eddy diffusion coefficient.

Science.gov (United States)

Shao, Yuan; Ramachandran, Sandhya; Arnold, Susan; Ramachandran, Gurumurthy

2017-03-01

The use of the turbulent eddy diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic eddy diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by eddy diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43-2.89 ACHs). An eddy diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent eddy diffusion models for exposure assessment in workplace/indoor environments more practical.

Modelling ecological and human exposure to POPs in Venice lagoon - Part II: Quantitative uncertainty and sensitivity analysis in coupled exposure models.

Science.gov (United States)

Radomyski, Artur; Giubilato, Elisa; Ciffroy, Philippe; Critto, Andrea; Brochot, Céline; Marcomini, Antonio

2016-11-01

The study is focused on applying uncertainty and sensitivity analysis to support the application and evaluation of large exposure models where a significant number of parameters and complex exposure scenarios might be involved. The recently developed MERLIN-Expo exposure modelling tool was applied to probabilistically assess the ecological and human exposure to PCB 126 and 2,3,7,8-TCDD in the Venice lagoon (Italy). The 'Phytoplankton', 'Aquatic Invertebrate', 'Fish', 'Human intake' and PBPK models available in MERLIN-Expo library were integrated to create a specific food web to dynamically simulate bioaccumulation in various aquatic species and in the human body over individual lifetimes from 1932 until 1998. MERLIN-Expo is a high tier exposure modelling tool allowing propagation of uncertainty on the model predictions through Monte Carlo simulation. Uncertainty in model output can be further apportioned between parameters by applying built-in sensitivity analysis tools. In this study, uncertainty has been extensively addressed in the distribution functions to describe the data input and the effect on model results by applying sensitivity analysis techniques (screening Morris method, regression analysis, and variance-based method EFAST). In the exposure scenario developed for the Lagoon of Venice, the concentrations of 2,3,7,8-TCDD and PCB 126 in human blood turned out to be mainly influenced by a combination of parameters (half-lives of the chemicals, body weight variability, lipid fraction, food assimilation efficiency), physiological processes (uptake/elimination rates), environmental exposure concentrations (sediment, water, food) and eating behaviours (amount of food eaten). In conclusion, this case study demonstrated feasibility of MERLIN-Expo to be successfully employed in integrated, high tier exposure assessment. Copyright © 2016 Elsevier B.V. All rights reserved.

Biodegradation kinetics for pesticide exposure assessment.

Science.gov (United States)

Wolt, J D; Nelson, H P; Cleveland, C B; van Wesenbeeck, I J

2001-01-01

Understanding pesticide risks requires characterizing pesticide exposure within the environment in a manner that can be broadly generalized across widely varied conditions of use. The coupled processes of sorption and soil degradation are especially important for understanding the potential environmental exposure of pesticides. The data obtained from degradation studies are inherently variable and, when limited in extent, lend uncertainty to exposure characterization and risk assessment. Pesticide decline in soils reflects dynamically coupled processes of sorption and degradation that add complexity to the treatment of soil biodegradation data from a kinetic perspective. Additional complexity arises from study design limitations that may not fully account for the decline in microbial activity of test systems, or that may be inadequate for considerations of all potential dissipation routes for a given pesticide. Accordingly, kinetic treatment of data must accommodate a variety of differing approaches starting with very simple assumptions as to reaction dynamics and extending to more involved treatments if warranted by the available experimental data. Selection of the appropriate kinetic model to describe pesticide degradation should rely on statistical evaluation of the data fit to ensure that the models used are not overparameterized. Recognizing the effects of experimental conditions and methods for kinetic treatment of degradation data is critical for making appropriate comparisons among pesticide biodegradation data sets. Assessment of variability in soil half-life among soils is uncertain because for many pesticides the data on soil degradation rate are limited to one or two soils. Reasonable upper-bound estimates of soil half-life are necessary in risk assessment so that estimated environmental concentrations can be developed from exposure models. Thus, an understanding of the variable and uncertain distribution of soil half-lives in the environment is

Modelling survival: exposure pattern, species sensitivity and uncertainty.

Science.gov (United States)

Ashauer, Roman; Albert, Carlo; Augustine, Starrlight; Cedergreen, Nina; Charles, Sandrine; Ducrot, Virginie; Focks, Andreas; Gabsi, Faten; Gergs, André; Goussen, Benoit; Jager, Tjalling; Kramer, Nynke I; Nyman, Anna-Maija; Poulsen, Veronique; Reichenberger, Stefan; Schäfer, Ralf B; Van den Brink, Paul J; Veltman, Karin; Vogel, Sören; Zimmer, Elke I; Preuss, Thomas G

2016-07-06

The General Unified Threshold model for Survival (GUTS) integrates previously published toxicokinetic-toxicodynamic models and estimates survival with explicitly defined assumptions. Importantly, GUTS accounts for time-variable exposure to the stressor. We performed three studies to test the ability of GUTS to predict survival of aquatic organisms across different pesticide exposure patterns, time scales and species. Firstly, using synthetic data, we identified experimental data requirements which allow for the estimation of all parameters of the GUTS proper model. Secondly, we assessed how well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates to build species sensitivity distributions for different exposure patterns. We find that GUTS adequately predicts survival across exposure patterns that vary over time. When toxicity is assessed for time-variable concentrations species may differ in their responses depending on the exposure profile. This can result in different species sensitivity rankings and safe levels. The interplay of exposure pattern and species sensitivity deserves systematic investigation in order to better understand how organisms respond to stress, including humans.

Assessment of human exposure to environmental sources of nickel in Europe: Inhalation exposure.

Science.gov (United States)

Buekers, Jurgen; De Brouwere, Katleen; Lefebvre, Wouter; Willems, Hanny; Vandenbroele, Marleen; Van Sprang, Patrick; Eliat-Eliat, Maxime; Hicks, Keegan; Schlekat, Christian E; Oller, Adriana R

2015-07-15

The paper describes the inhalation nickel (Ni) exposure of humans via the environment for the regional scale in the EU, together with a tiered approach for assessing additional local exposure from industrial emissions. The approach was designed, in the context of REACH, for the purpose of assessing and controlling emissions and air quality in the neighbourhood of Ni producers and downstream users. Two Derived No Effect Level (DNEL) values for chronic inhalation exposure to total Ni in PM10 (20 and 60ngNi/m(3)) were considered. The value of 20ngNi/m(3) is the current EU air quality guidance value. The value of 60ngNi/m(3) is derived here based on recently published Ni data (Oller et al., 2014). Both values are protective for respiratory toxicity and carcinogenicity but differ in the application of toxicokinetic adjustments and cancer threshold considerations. Estimates of air Ni concentrations at the European regional scale were derived from the database of the European Environment Agency. The 50th and 90th percentile regional exposures were below both DNEL values. To assess REACH compliance at the local scale, measured ambient air data are preferred but are often unavailable. A tiered approach for the use of modelled ambient air concentrations was developed, starting with the application of the default EUSES model and progressing to more sophisticated models. As an example, the tiered approach was applied to 33 EU Ni sulphate producers' and downstream users' sites. Applying the EUSES model demonstrates compliance with a DNEL of 60ngNi/m(3) for the majority of sites, while the value of the refined modelling is demonstrated when a DNEL of 20ngNi/m(3) is considered. The proposed approach, applicable to metals in general, can be used in the context of REACH, for refining the risk characterisation and guiding the selection of risk management measures. Copyright © 2015 Elsevier B.V. All rights reserved.

ASSESSING CHILDREN'S EXPOSURES TO PESTICIDES: AN IMPORTANT APPLICATION OF THE STOCHASTIC HUMAN EXPOSURE AND DOSE SIMULATION MODEL (SHEDS)

Science.gov (United States)

Accurately quantifying human exposures and doses of various populations to environmental pollutants is critical for the Agency to assess and manage human health risks. For example, the Food Quality Protection Act of 1996 (FQPA) requires EPA to consider aggregate human exposure ...

Optimum modellings of atmospheric diffusion of radioactive effluents and exposure doses in the accident consequence assessment (Level 3 PSA)

International Nuclear Information System (INIS)

Kim, Byung Woo; Lee, Young Bok; Han, Moon Hee; Kim, Eun Han; Suh, Kyung Suk; Hwang, Won Tae

1992-12-01

Atmospheric diffusion and exposure strongly dependent on the environment were firstly considered in the full spectrum of accident consequence assessment to establish based on Korean conditions. An optimum weather category based on Korean climate and site-specific meteorology of Kori region was established by statistical analysis of measured data for 10 years. And a trajectory model was selected as the optimal one in the ACA by reviewing several existing diffusion models. Following aspects were considered in this selection as availability of meteorological data, ability to treat the change to wind direction, easy applicability of the model, and restriction of CPU time and core memory in current computers. Numerical integration method of our own was selected as the optimal dose assessment tool of external exposure. Unit dose rate was firstly computed with this method as the function of energy level of radionuclide, size of lattice, and distance between source and receptor, and then the results were rearranged as the data library for the rapid access to the ACA run. Dynamic ecosystem modelling has been done in order to estimate the seasonal variation of radioactivity for the assessment of ingestion exposure, considering Korean ingestion behavior, agricultural practice and the transportation. There is a lot of uncertainty in a countermeasure model due to the assumed values of parameters such as fraction of population with different shielding factor and driving speed. A new countermeasure model was developed using the concept of fuzzy set theory, since it provided the mathematical tools which could characterize the uncertainty involved in countermeasure modelling. (Author)

Assessment of mankind's exposure through his environment: new tools and aid to decision - Colloquium report

International Nuclear Information System (INIS)

Thierry-Mieg, Morgane; Rousset, Marine; Varkados-Lemarechal, Margaret

2012-01-01

During this colloquium, the different sessions addressed environmental measurement strategies to assess mankind's exposure, the use and the interpretation of exposure bio-markers, the estimation and reconstruction of exposures (integrated modelling, model-measurement coupling), the organization and motives of dialogue between involved parties. Round tables addressed topics such as: measurement strategies and objectives, bio-availability of soil pollutants, approaches and tools for exposure assessment, new methodological strategies for the assessment of chemical exposure, interpretation of bio-markers, reference toxicological values, interest of bio-monitoring in professional environment, transcriptomic analysis, evolutions in the characterization of genotoxic hazards, a tool for the assessment of the exposure of newborn children to pesticides, and so on

Assessment of exposure dose to workers in virtual decommissioning environments

International Nuclear Information System (INIS)

Jeong, KwanSeong; Moon, JeiKwon; Choi, ByungSeon; Hyun, Dongjun; Lee, Jonghwan; Kim, Ikjune; Kim, GeunHo; Seo, JaeSeok

2014-01-01

This paper is intended to suggest the method analyze and assess the exposure dose to workers in virtual decommissioning environments. To simulate a lot of decommissioning scenarios, decommissioning environments were designed in virtual reality. To simulate and assess the exposure dose to workers, human model also was designed in virtual environments. These virtual decommissioning environments made it possible to real-time simulate and assess the exposure dose to workers. This work was to be able to simulate scenarios of decommissioning so that exposure dose to workers could be measured and assessed. To establish the plan of exposure dose to workers during decommissioning of nuclear facilities before decommissioning activities are accomplished, the method of simulation assessment was developed in virtual radiological environments. But this work was developed as a tool of simulation for single subject mode. Afterwards, the simulation environment for multi-subjects mode will be upgraded by simultaneous modules with networking environments. Then the much more practical method will be developed by changing number of workers and duration of time under any circumstances of decommissioning

Assessment of exposure dose to workers in virtual decommissioning environments

Energy Technology Data Exchange (ETDEWEB)

Jeong, KwanSeong; Moon, JeiKwon; Choi, ByungSeon; Hyun, Dongjun; Lee, Jonghwan; Kim, Ikjune; Kim, GeunHo; Seo, JaeSeok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

This paper is intended to suggest the method analyze and assess the exposure dose to workers in virtual decommissioning environments. To simulate a lot of decommissioning scenarios, decommissioning environments were designed in virtual reality. To simulate and assess the exposure dose to workers, human model also was designed in virtual environments. These virtual decommissioning environments made it possible to real-time simulate and assess the exposure dose to workers. This work was to be able to simulate scenarios of decommissioning so that exposure dose to workers could be measured and assessed. To establish the plan of exposure dose to workers during decommissioning of nuclear facilities before decommissioning activities are accomplished, the method of simulation assessment was developed in virtual radiological environments. But this work was developed as a tool of simulation for single subject mode. Afterwards, the simulation environment for multi-subjects mode will be upgraded by simultaneous modules with networking environments. Then the much more practical method will be developed by changing number of workers and duration of time under any circumstances of decommissioning.

Addressing bystander exposure to agricultural pesticides in life cycle impact assessment

DEFF Research Database (Denmark)

Ryberg, Morten Walbech; Rosenbaum, Ralph K.; Mosqueron, Luc

2018-01-01

Residents living near agricultural fields may be exposed to pesticides drifting from the fields after application to different field crops. To address this currently missing exposure pathway in life cycle assessment (LCA), we developed a modeling framework for quantifying exposure of bystanders...... magnitude of individual bystanders can be substantially larger than the exposure of populations not living in the proximity to agricultural fields. Our framework for assessing bystander exposure to pesticide applications closes a relevant gap in the exposure assessment included in LCA for agricultural...... to pesticide spray drift from agricultural fields. Our framework consists of three parts addressing: (1) loss of pesticides from an agricultural field via spray drift; (2) environmental fate of pesticide in air outside of the treated field; and (3) exposure of bystanders to pesticides via inhalation...

Modelling of individual subject ozone exposure response kinetics.

Science.gov (United States)

Schelegle, Edward S; Adams, William C; Walby, William F; Marion, M Susan

2012-06-01

A better understanding of individual subject ozone (O(3)) exposure response kinetics will provide insight into how to improve models used in the risk assessment of ambient ozone exposure. To develop a simple two compartment exposure-response model that describes individual subject decrements in forced expiratory volume in one second (FEV(1)) induced by the acute inhalation of O(3) lasting up to 8 h. FEV(1) measurements of 220 subjects who participated in 14 previously completed studies were fit to the model using both particle swarm and nonlinear least squares optimization techniques to identify three subject-specific coefficients producing minimum "global" and local errors, respectively. Observed and predicted decrements in FEV(1) of the 220 subjects were used for validation of the model. Further validation was provided by comparing the observed O(3)-induced FEV(1) decrements in an additional eight studies with predicted values obtained using model coefficients estimated from the 220 subjects used in cross validation. Overall the individual subject measured and modeled FEV(1) decrements were highly correlated (mean R(2) of 0.69 ± 0.24). In addition, it was shown that a matrix of individual subject model coefficients can be used to predict the mean and variance of group decrements in FEV(1). This modeling approach provides insight into individual subject O(3) exposure response kinetics and provides a potential starting point for improving the risk assessment of environmental O(3) exposure.

Assessment of inhomogeneous ELF magnetic field exposures

International Nuclear Information System (INIS)

Leitgeb, N.; Cech, R.; Schroettner, J.

2008-01-01

In daily life as well as at workplaces, exposures to inhomogeneous magnetic fields become very frequent. This makes easily applicable compliance assessment methods increasingly important. Reference levels have been defined linking basic restrictions to levels of homogeneous fields at worst-case exposure conditions. If reference levels are met, compliance with basic restrictions can be assumed. If not, further investigations could still prove compliance. Because of the lower induction efficiency, inhomogeneous magnetic fields such as from electric appliances could be allowed exceeding reference levels. To easily assess inhomogeneous magnetic fields, a quick and flexible multi-step assessment procedure is proposed. On the basis of simulations with numerical, anatomical human models reference factors were calculated elevating reference levels to link hot-spot values measured at source surfaces to basic limits and allowing accounting for different source distance, size, orientation and position. Compliance rules are proposed minimising assessment efforts. (authors)

Prioritizing Chemicals and Data Requirements for Screening-Level Exposure and Risk Assessment

Science.gov (United States)

Brown, Trevor N.; Wania, Frank; Breivik, Knut; McLachlan, Michael S.

2012-01-01

Background: Scientists and regulatory agencies strive to identify chemicals that may cause harmful effects to humans and the environment; however, prioritization is challenging because of the large number of chemicals requiring evaluation and limited data and resources. Objectives: We aimed to prioritize chemicals for exposure and exposure potential and obtain a quantitative perspective on research needs to better address uncertainty in screening assessments. Methods: We used a multimedia mass balance model to prioritize > 12,000 organic chemicals using four far-field human exposure metrics. The propagation of variance (uncertainty) in key chemical information used as model input for calculating exposure metrics was quantified. Results: Modeled human concentrations and intake rates span approximately 17 and 15 orders of magnitude, respectively. Estimates of exposure potential using human concentrations and a unit emission rate span approximately 13 orders of magnitude, and intake fractions span 7 orders of magnitude. The actual chemical emission rate contributes the greatest variance (uncertainty) in exposure estimates. The human biotransformation half-life is the second greatest source of uncertainty in estimated concentrations. In general, biotransformation and biodegradation half-lives are greater sources of uncertainty in modeled exposure and exposure potential than chemical partition coefficients. Conclusions: Mechanistic exposure modeling is suitable for screening and prioritizing large numbers of chemicals. By including uncertainty analysis and uncertainty in chemical information in the exposure estimates, these methods can help identify and address the important sources of uncertainty in human exposure and risk assessment in a systematic manner. PMID:23008278

Prioritizing chemicals and data requirements for screening-level exposure and risk assessment.

Science.gov (United States)

Arnot, Jon A; Brown, Trevor N; Wania, Frank; Breivik, Knut; McLachlan, Michael S

2012-11-01

Scientists and regulatory agencies strive to identify chemicals that may cause harmful effects to humans and the environment; however, prioritization is challenging because of the large number of chemicals requiring evaluation and limited data and resources. We aimed to prioritize chemicals for exposure and exposure potential and obtain a quantitative perspective on research needs to better address uncertainty in screening assessments. We used a multimedia mass balance model to prioritize > 12,000 organic chemicals using four far-field human exposure metrics. The propagation of variance (uncertainty) in key chemical information used as model input for calculating exposure metrics was quantified. Modeled human concentrations and intake rates span approximately 17 and 15 orders of magnitude, respectively. Estimates of exposure potential using human concentrations and a unit emission rate span approximately 13 orders of magnitude, and intake fractions span 7 orders of magnitude. The actual chemical emission rate contributes the greatest variance (uncertainty) in exposure estimates. The human biotransformation half-life is the second greatest source of uncertainty in estimated concentrations. In general, biotransformation and biodegradation half-lives are greater sources of uncertainty in modeled exposure and exposure potential than chemical partition coefficients. Mechanistic exposure modeling is suitable for screening and prioritizing large numbers of chemicals. By including uncertainty analysis and uncertainty in chemical information in the exposure estimates, these methods can help identify and address the important sources of uncertainty in human exposure and risk assessment in a systematic manner.

A Review of Exposure Assessment Methods in Epidemiological Studies on Incinerators

Directory of Open Access Journals (Sweden)

Michele Cordioli

2013-01-01

Full Text Available Incineration is a common technology for waste disposal, and there is public concern for the health impact deriving from incinerators. Poor exposure assessment has been claimed as one of the main causes of inconsistency in the epidemiological literature. We reviewed 41 studies on incinerators published between 1984 and January 2013 and classified them on the basis of exposure assessment approach. Moreover, we performed a simulation study to explore how the different exposure metrics may influence the exposure levels used in epidemiological studies. 19 studies used linear distance as a measure of exposure to incinerators, 11 studies atmospheric dispersion models, and the remaining 11 studies a qualitative variable such as presence/absence of the source. All reviewed studies utilized residence as a proxy for population exposure, although residence location was evaluated with different precision (e.g., municipality, census block, or exact address. Only one study reconstructed temporal variability in exposure. Our simulation study showed a notable degree of exposure misclassification caused by the use of distance compared to dispersion modelling. We suggest that future studies (i make full use of pollution dispersion models; (ii localize population on a fine-scale; and (iii explicitly account for the presence of potential environmental and socioeconomic confounding.

Optimizing cost-efficiency in mean exposure assessment--cost functions reconsidered.

Science.gov (United States)

Mathiassen, Svend Erik; Bolin, Kristian

2011-05-21

Reliable exposure data is a vital concern in medical epidemiology and intervention studies. The present study addresses the needs of the medical researcher to spend monetary resources devoted to exposure assessment with an optimal cost-efficiency, i.e. obtain the best possible statistical performance at a specified budget. A few previous studies have suggested mathematical optimization procedures based on very simple cost models; this study extends the methodology to cover even non-linear cost scenarios. Statistical performance, i.e. efficiency, was assessed in terms of the precision of an exposure mean value, as determined in a hierarchical, nested measurement model with three stages. Total costs were assessed using a corresponding three-stage cost model, allowing costs at each stage to vary non-linearly with the number of measurements according to a power function. Using these models, procedures for identifying the optimally cost-efficient allocation of measurements under a constrained budget were developed, and applied on 225 scenarios combining different sizes of unit costs, cost function exponents, and exposure variance components. Explicit mathematical rules for identifying optimal allocation could be developed when cost functions were linear, while non-linear cost functions implied that parts of or the entire optimization procedure had to be carried out using numerical methods.For many of the 225 scenarios, the optimal strategy consisted in measuring on only one occasion from each of as many subjects as allowed by the budget. Significant deviations from this principle occurred if costs for recruiting subjects were large compared to costs for setting up measurement occasions, and, at the same time, the between-subjects to within-subject variance ratio was small. In these cases, non-linearities had a profound influence on the optimal allocation and on the eventual size of the exposure data set. The analysis procedures developed in the present study can be used

CalTOX, a multimedia total exposure model for hazardous-waste sites

International Nuclear Information System (INIS)

McKone, T.E.

1993-06-01

CalTOX has been developed as a spreadsheet model to assist in health-risk assessments that address contaminated soils and the contamination of adjacent air, surface water, sediments, and ground water. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify and reduce uncertainty in multimedia, multiple-pathway exposure models. This report provides an overview of the CalTOX model components, lists the objectives of the model, describes the philosophy under which the model was developed, identifies the chemical classes for which the model can be used, and describes critical sensitivities and uncertainties. The multimedia transport and transformation model is a dynamic model that can be used to assess time-varying concentrations of contaminants introduced initially to soil layers or for contaminants released continuously to air or water. This model assists the user in examining how chemical and landscape properties impact both the ultimate route and quantity of human contact. Multimedia, multiple pathway exposure models are used in the CalTOX model to estimate average daily potential doses within a human population in the vicinity of a hazardous substances release site. The exposure models encompass twenty-three exposure pathways. The exposure assessment process consists of relating contaminant concentrations in the multimedia model compartments to contaminant concentrations in the media with which a human population has contact (personal air, tap water, foods, household dusts soils, etc.). The average daily dose is the product of the exposure concentrations in these contact media and an intake or uptake factor that relates the concentrations to the distributions of potential dose within the population

Assessment and improvement of biotransfer models to cow's milk and beef used in exposure assessment tools for organic pollutants.

Science.gov (United States)

Takaki, Koki; Wade, Andrew J; Collins, Chris D

2015-11-01

The aim of this study was to assess and improve the accuracy of biotransfer models for the organic pollutants (PCBs, PCDD/Fs, PBDEs, PFCAs, and pesticides) into cow's milk and beef used in human exposure assessment. Metabolic rate in cattle is known as a key parameter for this biotransfer, however few experimental data and no simulation methods are currently available. In this research, metabolic rate was estimated using existing QSAR biodegradation models of microorganisms (BioWIN) and fish (EPI-HL and IFS-HL). This simulated metabolic rate was then incorporated into the mechanistic cattle biotransfer models (RAIDAR, ACC-HUMAN, OMEGA, and CKow). The goodness of fit tests showed that RAIDAR, ACC-HUMAN, OMEGA model performances were significantly improved using either of the QSARs when comparing the new model outputs to observed data. The CKow model is the only one that separates the processes in the gut and liver. This model showed the lowest residual error of all the models tested when the BioWIN model was used to represent the ruminant metabolic process in the gut and the two fish QSARs were used to represent the metabolic process in the liver. Our testing included EUSES and CalTOX which are KOW-regression models that are widely used in regulatory assessment. New regressions based on the simulated rate of the two metabolic processes are also proposed as an alternative to KOW-regression models for a screening risk assessment. The modified CKow model is more physiologically realistic, but has equivalent usability to existing KOW-regression models for estimating cattle biotransfer of organic pollutants. Copyright © 2015. Published by Elsevier Ltd.

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.

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.

Risk assessment of exposure to radon decay products

Energy Technology Data Exchange (ETDEWEB)

Monchaux, G

1999-07-01

The aim of this project was to assess the risk due to inhalation of radon and its decay products using an horizontal approach across a large scale research programme. The central objective was the assessment of human risk which requires combination of several topics involving a multidisciplinary approach. In the Aerosol Studies Group, progress was achieved in improvement, calibration and automation of experimental techniques for continuous and integrated measurements of the unattached fraction f{sub p}- and equilibrium factor F- values. Measurements were performed to determine the variation of size distributions of unattached and aerosol-associated radon decay products under typical living conditions. All aerosol groups performed controlled chamber studies to understand the basic behaviour of airborne activity concentrations. Measurements were performed to determine neutralisation rates of {sup 218}Po, to understand the cluster growth with residence time and to understand the hygroscopic growth of aerosol particles. In the Modelling Group, the programme RADEP has been developed to calculate the weighted committed equivalent lung dose per unit exposure of radon progeny (H{sub w}/P{sub p}) which implements the ICRP Publication 66 Human Respiratory Tract Model (HRTM). The stochastic deposition model (IDEAL) has been compared with the deposition model used by the HRTM, and the agreement between the two deposition models was excellent. A deterministic radon progeny dosimetry model (RADOS) has been developed. This model includes all bronchial airway generations compared with the HRTM that groups the 16 airway generations into three regions. Initial calculations with RADOS show that the basal and secretory cell doses are slightly smaller compared with that of the HRTM. A sensitivity analysis has been performed that has identified those HRTM model parameters that most affect the Hw/Pp. A stochastic rat deposition model (RALMO) and a clearance model for the rat based on the

Risk assessment of exposure to radon decay products

International Nuclear Information System (INIS)

Monchaux, G.

1999-01-01

The aim of this project was to assess the risk due to inhalation of radon and its decay products using an horizontal approach across a large scale research programme. The central objective was the assessment of human risk which requires combination of several topics involving a multidisciplinary approach. In the Aerosol Studies Group, progress was achieved in improvement, calibration and automation of experimental techniques for continuous and integrated measurements of the unattached fraction f p - and equilibrium factor F- values. Measurements were performed to determine the variation of size distributions of unattached and aerosol-associated radon decay products under typical living conditions. All aerosol groups performed controlled chamber studies to understand the basic behaviour of airborne activity concentrations. Measurements were performed to determine neutralisation rates of 218 Po, to understand the cluster growth with residence time and to understand the hygroscopic growth of aerosol particles. In the Modelling Group, the programme RADEP has been developed to calculate the weighted committed equivalent lung dose per unit exposure of radon progeny (H w /P p ) which implements the ICRP Publication 66 Human Respiratory Tract Model (HRTM). The stochastic deposition model (IDEAL) has been compared with the deposition model used by the HRTM, and the agreement between the two deposition models was excellent. A deterministic radon progeny dosimetry model (RADOS) has been developed. This model includes all bronchial airway generations compared with the HRTM that groups the 16 airway generations into three regions. Initial calculations with RADOS show that the basal and secretory cell doses are slightly smaller compared with that of the HRTM. A sensitivity analysis has been performed that has identified those HRTM model parameters that most affect the Hw/Pp. A stochastic rat deposition model (RALMO) and a clearance model for the rat based on the HRTM have been

Evaluation of semi-generic PBTK modeling for emergency risk assessment after acute inhalation exposure to volatile hazardous chemicals

NARCIS (Netherlands)

Olie, J Daniël N; Bessems, Jos G; Clewell, Harvey J; Meulenbelt, Jan; Hunault, Claudine C

BACKGROUND: Physiologically Based Toxicokinetic Models (PBTK) may facilitate emergency risk assessment after chemical incidents with inhalation exposure, but they are rarely used due to their relative complexity and skill requirements. We aimed to tackle this problem by evaluating a semi-generic

Evaluation of semi-generic PBTK modeling for emergency risk assessment after acute inhalation exposure to volatile hazardous chemicals

NARCIS (Netherlands)

Olie, J. Daniël N; Bessems, Jos G.; Clewell, Harvey J.; Meulenbelt, Jan; Hunault, Claudine C.

2015-01-01

BACKGROUND: Physiologically Based Toxicokinetic Models (PBTK) may facilitate emergency risk assessment after chemical incidents with inhalation exposure, but they are rarely used due to their relative complexity and skill requirements. We aimed to tackle this problem by evaluating a semi-generic

Human Exposure Model (HEM): A modular, web-based application to characterize near-field chemical exposures and releases

Science.gov (United States)

The U.S. EPA’s Chemical Safety and Sustainability research program is developing the Human Exposure Model (HEM) to assess near-field exposures to chemicals that occur in various populations over the entire life cycle of a consumer product. The model will be implemented as a...

Exposure assessment and modeling of particulate matter for asthmatic children using personal nephelometers

Science.gov (United States)

Wu, Chang-Fu; Delfino, Ralph J.; Floro, Joshua N.; Quintana, Penelope J. E.; Samimi, Behzad S.; Kleinman, Michael T.; Allen, Ryan W.; Sally Liu, L.-J.

It has been shown that acute exposures to particulate matter (PM) may exacerbate asthma in children. However, most epidemiological studies have relied on time-integrated PM measurements taken at a centrally located stationary monitoring sites. In this article, we characterized children's short-term personal exposures to PM 2.5 (PM with aerodynamic diameters size-selective inlet was used to estimate real-time PM 2.5 concentrations on 20 asthmatic children, inside and outside of their residences, and at a central site. The personal and indoor pDRs were operated passively, while the home outdoor and central site instruments were operated actively. The subjects received 29.2% of their exposures at school, even though they only spent 16.4% of their time there. More precise personal clouds were estimated for the home-indoor and home-outdoor microenvironments where PM concentrations were measured. The personal cloud increased with increasing activity levels and was higher during outdoor activities than during indoor activities. We built models to predict personal PM exposures based on either microenvironmental or central-site PM 2.5 measurements, and evaluated the modeled exposures against the actual personal measurements. A multiple regression model with central site PM concentration as the main predictor had a better prediction power ( R2=0.41) than a three-microenvironmental model ( R2=0.11). We further constructed a source-specific exposure model utilizing the time-space-activity information and the particle infiltration efficiencies (mean=0.72±0.15) calculated from a recursive mass balance model. It was estimated that the mean hourly personal exposures resulting from ambient, indoor-generated, and personal activity PM 2.5 were 11.1, 5.5, and 10.0 μg/m 3, respectively, when the modeling error was minimized. The high PM 2.5 exposure to personal activities reported in our study is likely due to children's more active lifestyle as compared with older adult subjects in

Chapter three: methodology of exposure modeling

CSIR Research Space (South Africa)

Moschandreas, DJ

2002-12-01

Full Text Available methodologies and models are reviewed. Three exposure/measurement methodologies are assessed. Estimation methods focus on source evaluation and attribution, sources include those outdoors and indoors as well as in occupational and in-transit environments. Fate...

Parameterization models for pesticide exposure via crop consumption.

Science.gov (United States)

Fantke, Peter; Wieland, Peter; Juraske, Ronnie; Shaddick, Gavin; Itoiz, Eva Sevigné; Friedrich, Rainer; Jolliet, Olivier

2012-12-04

An approach for estimating human exposure to pesticides via consumption of six important food crops is presented that can be used to extend multimedia models applied in health risk and life cycle impact assessment. We first assessed the variation of model output (pesticide residues per kg applied) as a function of model input variables (substance, crop, and environmental properties) including their possible correlations using matrix algebra. We identified five key parameters responsible for between 80% and 93% of the variation in pesticide residues, namely time between substance application and crop harvest, degradation half-lives in crops and on crop surfaces, overall residence times in soil, and substance molecular weight. Partition coefficients also play an important role for fruit trees and tomato (Kow), potato (Koc), and lettuce (Kaw, Kow). Focusing on these parameters, we develop crop-specific models by parametrizing a complex fate and exposure assessment framework. The parametric models thereby reflect the framework's physical and chemical mechanisms and predict pesticide residues in harvest using linear combinations of crop, crop surface, and soil compartments. Parametric model results correspond well with results from the complex framework for 1540 substance-crop combinations with total deviations between a factor 4 (potato) and a factor 66 (lettuce). Predicted residues also correspond well with experimental data previously used to evaluate the complex framework. Pesticide mass in harvest can finally be combined with reduction factors accounting for food processing to estimate human exposure from crop consumption. All parametric models can be easily implemented into existing assessment frameworks.

A hybrid modeling with data assimilation to evaluate human exposure level

Science.gov (United States)

Koo, Y. S.; Cheong, H. K.; Choi, D.; Kim, A. L.; Yun, H. Y.

2015-12-01

Exposure models are designed to better represent human contact with PM (Particulate Matter) and other air pollutants such as CO, SO2, O3, and NO2. The exposure concentrations of the air pollutants to human are determined by global and regional long range transport of global and regional scales from Europe and China as well as local emissions from urban and road vehicle sources. To assess the exposure level in detail, the multiple scale influence from background to local sources should be considered. A hybrid air quality modeling methodology combing a grid-based chemical transport model with a local plume dispersion model was used to provide spatially and temporally resolved air quality concentration for human exposure levels in Korea. In the hybrid modeling approach, concentrations from a grid-based chemical transport model and a local plume dispersion model are added to provide contributions from photochemical interactions, long-range (regional) transport and local-scale dispersion. The CAMx (Comprehensive Air quality Model with Extensions was used for the background concentrations from anthropogenic and natural emissions in East Asia including Korea while the road dispersion by vehicle emission was calculated by CALPUFF model. The total exposure level of the pollutants was finally assessed by summing the background and road contributions. In the hybrid modeling, the data assimilation method based on the optimal interpolation was applied to overcome the discrepancies between the model predicted concentrations and observations. The air quality data from the air quality monitoring stations in Korea. The spatial resolution of the hybrid model was 50m for the Seoul Metropolitan Ares. This example clearly demonstrates that the exposure level could be estimated to the fine scale for the exposure assessment by using the hybrid modeling approach with data assimilation.

A flexible matrix-based human exposure assessment framework suitable for LCA and CAA

DEFF Research Database (Denmark)

Jolliet, Olivier; Ernstoff, Alexi; Huang, Lei

2016-01-01

are not applicable to all types of near-field chemical releases from consumer products, e.g. direct dermal application. A consistent near-and far-field framework is needed for life cycle assessment (LCA) and chemical alternative assessment (CAA) to inform mitigation of human exposure to harmful chemicals. To close......Humans can be exposed to chemicals via near-field exposure pathways (e.g. through consumer product use) and far-field exposure pathways (e.g. through environmental emissions along product life cycles). Pathways are often complex where chemicals can transfer directly from products to humans during...... use or exchange between near-and far-field compartments until sub -fractions reach humans via inhalation, ingestion or dermal uptake. Currently, however, multimedia exposure models mainly focus on far-field exposure pathways. Metrics and modeling approaches used in far-field, emission-based models...

Real-time assessment of exposure dose to workers in radiological environments during decommissioning of nuclear facilities

International Nuclear Information System (INIS)

Jeong, KwanSeong; Choi, ByungSeon; Moon, JeiKwon; Hyun, Dongjun; Lee, Jonghwan; Kim, IkJune; Kim, GeunHo; Seo, JaeSeok; Jeong, SeongYoung; Lee, JungJun; Song, HaeSang; Lee, SangWha; Son, BongKi

2014-01-01

Highlights: • The method of exposure dose assessment to workers during decommissioning of nuclear facilities. • The environments of simulation were designed under a virtual reality. • To assess exposure dose to workers, human model was developed within a virtual reality. - Abstract: This objective of this paper is to develop a method to simulate and assess the exposure dose to workers during decommissioning of nuclear facilities. To simulate several scenarios, decommissioning environments were designed using virtual reality. To assess exposure dose to workers, a human model was also developed using virtual reality. The exposure dose was measured and assessed under the principle of ALARA in accordance with radiological environmental change. This method will make it possible to plan for the exposure dose to workers during decommissioning of nuclear facilities

Combining exposure and effect modeling into an integrated probabilistic environmental risk assessment for nanoparticles.

Science.gov (United States)

Jacobs, Rianne; Meesters, Johannes A J; Ter Braak, Cajo J F; van de Meent, Dik; van der Voet, Hilko

2016-12-01

There is a growing need for good environmental risk assessment of engineered nanoparticles (ENPs). Environmental risk assessment of ENPs has been hampered by lack of data and knowledge about ENPs, their environmental fate, and their toxicity. This leads to uncertainty in the risk assessment. To deal with uncertainty in the risk assessment effectively, probabilistic methods are advantageous. In the present study, the authors developed a method to model both the variability and the uncertainty in environmental risk assessment of ENPs. This method is based on the concentration ratio and the ratio of the exposure concentration to the critical effect concentration, both considered to be random. In this method, variability and uncertainty are modeled separately so as to allow the user to see which part of the total variation in the concentration ratio is attributable to uncertainty and which part is attributable to variability. The authors illustrate the use of the method with a simplified aquatic risk assessment of nano-titanium dioxide. The authors' method allows a more transparent risk assessment and can also direct further environmental and toxicological research to the areas in which it is most needed. Environ Toxicol Chem 2016;35:2958-2967. © 2016 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC. © 2016 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

[The methods of assessment of health risk from exposure to radon and radon daughters].

Science.gov (United States)

Demin, V F; Zhukovskiy, M V; Kiselev, S M

2014-01-01

The critical analysis of existing models of the relationship dose-effect (RDE) for radon exposure on human health has been performed. Conclusion about the necessity and possibility of improving these models has been made. A new improved version ofthe RDE has been developed. A technique for assessing the human health risk of exposure to radon, including the method for estimating of exposure doses of radon, an improved model of RDE, proper methodology risk assessment has been described. Methodology is proposed for the use in the territory of Russia.

Probabilistic calculations and sensitivity analysis of parameters for a reference biosphere model assessing the potential exposure of a population to radionuclides from a deep geological repository

Energy Technology Data Exchange (ETDEWEB)

Staudt, Christian; Kaiser, Jan Christian [Helmholtz Zentrum Muenchen, Institute of Radiation Protection, Munich (Germany); Proehl, Gerhard [International Atomic Energy Agency, Division of Radiation, Transport and Waste Safety, Wagramerstrasse 5, 1400 Vienna (Austria)

2014-07-01

Radioecological models are used to assess the exposure of hypothetical populations to radionuclides. Potential radionuclide sources are deep geological repositories for high level radioactive waste. Assessment time frames are long since releases from those repositories are only expected in the far future, and radionuclide migration to the geosphere biosphere interface will take additional time. Due to the long time frames, climate conditions at the repository site will change, leading to changing exposure pathways and model parameters. To identify climate dependent changes in exposure in the far field of a deep geological repository a range of reference biosphere models representing climate analogues for potential future climate states at a German site were developed. In this approach, model scenarios are developed for different contemporary climate states. It is assumed that the exposure pathways and parameters of the contemporary biosphere in the far field of the repository will change to be similar to those at the analogue sites. Since current climate models cannot predict climate developments over the assessment time frame of 1 million years, analogues for a range of realistically possible future climate conditions were selected. These climate states range from steppe to permafrost climate. As model endpoint Biosphere Dose conversion factors (BDCF) are calculated. The radionuclide specific BDCF describe the exposure of a population to radionuclides entering the biosphere in near surface ground water. The BDCF are subject to uncertainties in the exposure pathways and model parameters. In the presented work, probabilistic and sensitivity analysis was used to assess the influence of model parameter uncertainties on the BDCF and the relevance of individual parameters for the model result. This was done for the long half-live radionuclides Cs-135, I-129 and U-238. In addition to this, BDCF distributions for nine climate reference regions and several scenarios were

The assessment of the aircrew exposure

International Nuclear Information System (INIS)

Tommasino, L.

2002-01-01

In 1991 ICRP first included exposure of aircraft crew to cosmic radiation as occupational exposure. The European Dosimetry Group (EURADOS) established a working group in 1992 to address this issue. The report 'Exposure of Air Crew to Cosmic Radiation' was published in the European Commission's Radiation Protection series as report 85. The first section of the report assesses the existing data on radiation exposure, describes the radiation environment at civil aviation altitudes and summarizes the computational models that have been developed to describe the cosmic ray radiation field in the atmosphere. The second section describes the quantities used to assess the radiation doses. It is clear that conventional radiation protection dosimetry as applied on the ground is not quite applicable to the situation for air crews. A multinational European research project was launched to investigate the problem of cosmic rays and dosimetry at aviation altitudes. The major objective was to measure the flux and energy spectra of neutrons and charged particles over a wide energy interval at aviation altitudes and compare the results with those calculated with various computer codes. Within the project much progress was made in different areas, for instance the determination of the fundamental physical characteristics of the cosmic radiation field at aircraft altitudes, development of instrumentation, measurements of dose rates and route doses and application of routine radiation protection. Surveys of air crew exposure have been carried out with different advanced dosimetric systems and comparisons were made between passive and real-time detector systems

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

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.

Primary blast survival and injury risk assessment for repeated blast exposures.

Science.gov (United States)

Panzer, Matthew B; Bass, Cameron R Dale; Rafaels, Karin A; Shridharani, Jay; Capehart, Bruce P

2012-02-01

The widespread use of explosives by modern insurgents and terrorists has increased the potential frequency of blast exposure in soldiers and civilians. This growing threat highlights the importance of understanding and evaluating blast injury risk and the increase of injury risk from exposure to repeated blast effects. Data from more than 3,250 large animal experiments were collected from studies focusing on the effects of blast exposure. The current study uses 2,349 experiments from the data collection for analysis of the primary blast injury and survival risk for both long- and short-duration blasts, including the effects from repeated exposures. A piecewise linear logistic regression was performed on the data to develop survival and injury risk assessment curves. New injury risk assessment curves uniting long- and short-duration blasts were developed for incident and reflected pressure measures and were used to evaluate the risk of injury based on blast over pressure, positive-phase duration, and the number of repeated exposures. The risk assessments were derived for three levels of injury severity: nonauditory, pulmonary, and fatality. The analysis showed a marked initial decrease in injury tolerance with each subsequent blast exposure. This effect decreases with increasing number of blast exposures. The new injury risk functions showed good agreement with the existing experimental data and provided a simplified model for primary blast injury risk. This model can be used to predict blast injury or fatality risk for single exposure and repeated exposure cases and has application in modern combat scenarios or in setting occupational health limits. .Copyright © 2012 by Lippincott Williams & Wilkins

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

Assessment of exposure-response functions for rocket-emission toxicants

National Research Council Canada - National Science Library

Subcommittee on Rocket-Emission Toxicants, National Research Council

... aborted launch that results in a rocket being destroyed near the ground. Assessment of Exposure-Response Functions for Rocket-Emmission Toxicants evaluates the model and the data used for three rocket emission toxicants...

Truncated Levy flights and agenda-based mobility are useful for the assessment of personal human exposure

International Nuclear Information System (INIS)

Schlink, Uwe; Ragas, Ad M.J.

2011-01-01

Receptor-oriented approaches can assess the individual-specific exposure to air pollution. In such an individual-based model we analyse the impact of human mobility to the personal exposure that is perceived by individuals simulated in an exemplified urban area. The mobility models comprise random walk (reference point mobility, RPM), truncated Levy flights (TLF), and agenda-based walk (RPMA). We describe and review the general concepts and provide an inter-comparison of these concepts. Stationary and ergodic behaviour are explained and applied as well as performance criteria for a comparative evaluation of the investigated algorithms. We find that none of the studied algorithm results in purely random trajectories. TLF and RPMA prove to be suitable for human mobility modelling, because they provide conditions for very individual-specific trajectories and exposure. Suggesting these models we demonstrate the plausibility of their results for exposure to air-borne benzene and the combined exposure to benzene and nonane. - Highlights: → Human exposure to air pollutants is influenced by a person's movement in the urban area. → We provide a simulation study of approaches to modelling personal exposure. → Agenda-based models and truncated Levy flights are recommended for exposure assessment. → The procedure is demonstrated for benzene exposure in an urban region. - Truncated Levy flights and agenda-based mobility are useful for the assessment of personal human exposure.

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.

Assessing global exposure and vulnerability towards natural hazards: the Disaster Risk Index

Directory of Open Access Journals (Sweden)

P. Peduzzi

2009-07-01

Full Text Available This paper presents a model of factors influencing levels of human losses from natural hazards at the global scale, for the period 1980–2000. This model was designed for the United Nations Development Programme as a building stone of the Disaster Risk Index (DRI, which aims at monitoring the evolution of risk. Assessing what countries are most at risk requires considering various types of hazards, such as droughts, floods, cyclones and earthquakes. Before assessing risk, these four hazards were modelled using GIS and overlaid with a model of population distribution in order to extract human exposure. Human vulnerability was measured by crossing exposure with selected socio-economic parameters. The model evaluates to what extent observed past losses are related to population exposure and vulnerability. Results reveal that human vulnerability is mostly linked with country development level and environmental quality. A classification of countries is provided, as well as recommendations on data improvement for future use of the model.

An approach for assessing human exposures to chemical mixtures in the environment

International Nuclear Information System (INIS)

Rice, Glenn; MacDonell, Margaret; Hertzberg, Richard C.; Teuschler, Linda; Picel, Kurt; Butler, Jim; Chang, Young-Soo; Hartmann, Heidi

2008-01-01

Humans are exposed daily to multiple chemicals, including incidental exposures to complex chemical mixtures released into the environment and to combinations of chemicals that already co-exist in the environment because of previous releases from various sources. Exposures to chemical mixtures can occur through multiple pathways and across multiple routes. In this paper, we propose an iterative approach for assessing exposures to environmental chemical mixtures; it is similar to single-chemical approaches. Our approach encompasses two elements of the Risk Assessment Paradigm: Problem Formulation and Exposure Assessment. Multiple phases of the assessment occur in each element of the paradigm. During Problem Formulation, analysts identify and characterize the source(s) of the chemical mixture, ensure that dose-response and exposure assessment measures are concordant, and develop a preliminary evaluation of the mixture's fate. During Exposure Assessment, analysts evaluate the fate of the chemicals comprising the mixture using appropriate models and measurement data, characterize the exposure scenario, and estimate human exposure to the mixture. We also describe the utility of grouping the chemicals to be analyzed based on both physical-chemical properties and an understanding of environmental fate. In the article, we also highlight the need for understanding of changes in the mixture composition in the environment due to differential transport, differential degradation, and differential partitioning to other media. The section describes the application of the method to various chemical mixtures, highlighting issues associated with assessing exposures to chemical mixtures in the environment

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

Tools for regulatory assessment of occupational exposure: Development and challenges

NARCIS (Netherlands)

Tielemans, E.; Warren, N.; Schneider, T.; Tischer, M.; Ritchie, P.; Goede, H.; Kromhout, H.; Hemmen, J. van; Cherrie, J.W.

2007-01-01

REACH (Registration, Evaluation and Authorization of CHemicals) requires improved exposure models that can be incorporated into screening tools and refined assessment tools. These are referred to as tier 1 and 2 models, respectively. There are a number of candidate in tier 1 models that could be

Evaluation of semi-generic PBTK modeling for emergency risk assessment after acute inhalation exposure to volatile hazardous chemicals.

Science.gov (United States)

Olie, J Daniël N; Bessems, Jos G; Clewell, Harvey J; Meulenbelt, Jan; Hunault, Claudine C

2015-08-01

Physiologically Based Toxicokinetic Models (PBTK) may facilitate emergency risk assessment after chemical incidents with inhalation exposure, but they are rarely used due to their relative complexity and skill requirements. We aimed to tackle this problem by evaluating a semi-generic PBTK model built in MS Excel for nine chemicals that are widely-used and often released in a chemical incident. The semi-generic PBTK model was used to predict blood concentration-time curves using inhalation exposure scenarios from human volunteer studies, case reports and hypothetical exposures at Emergency Response Planning Guideline, Level 3 (ERPG-3) levels.(2) Predictions using this model were compared with measured blood concentrations from volunteer studies or case reports, as well as blood concentrations predicted by chemical-specific models. The performances of the semi-generic model were evaluated on biological rationale, accuracy, and ease of use and range of application. Our results indicate that the semi-generic model can be easily used to predict blood levels for eight out of nine parent chemicals (dichloromethane, benzene, xylene, styrene, toluene, isopropanol trichloroethylene and tetrachloroethylene). However, for methanol, 2-propanol and dichloromethane the semi-generic model could not cope with the endogenous production of methanol and of acetone (being a metabolite of 2-propanol) nor could it simulate the formation of HbCO, which is one of the toxic end-points of dichloromethane. The model is easy and intuitive to use by people who are not so familiar with toxicokinetic models. A semi-generic PBTK modeling approach can be used as a 'quick-and-dirty' method to get a crude estimate of the exposure dose. Copyright © 2015 Elsevier Ltd. All rights reserved.

Road traffic air and noise pollution exposure assessment - A review of tools and techniques.

Science.gov (United States)

Khan, Jibran; Ketzel, Matthias; Kakosimos, Konstantinos; Sørensen, Mette; Jensen, Steen Solvang

2018-09-01

Road traffic induces air and noise pollution in urban environments having negative impacts on human health. Thus, estimating exposure to road traffic air and noise pollution (hereafter, air and noise pollution) is important in order to improve the understanding of human health outcomes in epidemiological studies. The aims of this review are (i) to summarize current practices of modelling and exposure assessment techniques for road traffic air and noise pollution (ii) to highlight the potential of existing tools and techniques for their combined exposure assessment for air and noise together with associated challenges, research gaps and priorities. The study reviews literature about air and noise pollution from urban road traffic, including other relevant characteristics such as the employed dispersion models, Geographic Information System (GIS)-based tool, spatial scale of exposure assessment, study location, sample size, type of traffic data and building geometry information. Deterministic modelling is the most frequently used assessment technique for both air and noise pollution of short-term and long-term exposure. We observed a larger variety among air pollution models as compared to the applied noise models. Correlations between air and noise pollution vary significantly (0.05-0.74) and are affected by several parameters such as traffic attributes, building attributes and meteorology etc. Buildings act as screens for the dispersion of pollution, but the reduction effect is much larger for noise than for air pollution. While, meteorology has a greater influence on air pollution levels as compared to noise, although also important for noise pollution. There is a significant potential for developing a standard tool to assess combined exposure of traffic related air and noise pollution to facilitate health related studies. GIS, due to its geographic nature, is well established and has a significant capability to simultaneously address both exposures. Copyright �

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

Exposure Assessment Tools by Tiers and Types - Deterministic and Probabilistic Assessments

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

Comparative Probabilistic Assessment of Occupational Pesticide Exposures Based on Regulatory Assessments

Science.gov (United States)

Pouzou, Jane G.; Cullen, Alison C.; Yost, Michael G.; Kissel, John C.; Fenske, Richard A.

2018-01-01

Implementation of probabilistic analyses in exposure assessment can provide valuable insight into the risks of those at the extremes of population distributions, including more vulnerable or sensitive subgroups. Incorporation of these analyses into current regulatory methods for occupational pesticide exposure is enabled by the exposure data sets and associated data currently used in the risk assessment approach of the Environmental Protection Agency (EPA). Monte Carlo simulations were performed on exposure measurements from the Agricultural Handler Exposure Database and the Pesticide Handler Exposure Database along with data from the Exposure Factors Handbook and other sources to calculate exposure rates for three different neurotoxic compounds (azinphos methyl, acetamiprid, emamectin benzoate) across four pesticide-handling scenarios. Probabilistic estimates of doses were compared with the no observable effect levels used in the EPA occupational risk assessments. Some percentage of workers were predicted to exceed the level of concern for all three compounds: 54% for azinphos methyl, 5% for acetamiprid, and 20% for emamectin benzoate. This finding has implications for pesticide risk assessment and offers an alternative procedure that may be more protective of those at the extremes of exposure than the current approach. PMID:29105804

Comparative Probabilistic Assessment of Occupational Pesticide Exposures Based on Regulatory Assessments.

Science.gov (United States)

Pouzou, Jane G; Cullen, Alison C; Yost, Michael G; Kissel, John C; Fenske, Richard A

2017-11-06

Implementation of probabilistic analyses in exposure assessment can provide valuable insight into the risks of those at the extremes of population distributions, including more vulnerable or sensitive subgroups. Incorporation of these analyses into current regulatory methods for occupational pesticide exposure is enabled by the exposure data sets and associated data currently used in the risk assessment approach of the Environmental Protection Agency (EPA). Monte Carlo simulations were performed on exposure measurements from the Agricultural Handler Exposure Database and the Pesticide Handler Exposure Database along with data from the Exposure Factors Handbook and other sources to calculate exposure rates for three different neurotoxic compounds (azinphos methyl, acetamiprid, emamectin benzoate) across four pesticide-handling scenarios. Probabilistic estimates of doses were compared with the no observable effect levels used in the EPA occupational risk assessments. Some percentage of workers were predicted to exceed the level of concern for all three compounds: 54% for azinphos methyl, 5% for acetamiprid, and 20% for emamectin benzoate. This finding has implications for pesticide risk assessment and offers an alternative procedure that may be more protective of those at the extremes of exposure than the current approach. © 2017 Society for Risk Analysis.

GPS-based microenvironment tracker (MicroTrac) model to estimate time-location of individuals for air pollution exposure assessments: model evaluation in central North Carolina.

Science.gov (United States)

Breen, Michael S; Long, Thomas C; Schultz, Bradley D; Crooks, James; Breen, Miyuki; Langstaff, John E; Isaacs, Kristin K; Tan, Yu-Mei; Williams, Ronald W; Cao, Ye; Geller, Andrew M; Devlin, Robert B; Batterman, Stuart A; Buckley, Timothy J

2014-07-01

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure to do so can add uncertainty and bias to risk estimates. In this study, a classification model, called MicroTrac, was developed to estimate time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from global positioning system (GPS) data and geocoded building boundaries. Based on a panel study, MicroTrac estimates were compared with 24-h diary data from nine participants, with corresponding GPS data and building boundaries of home, school, and work. MicroTrac correctly classified the ME for 99.5% of the daily time spent by the participants. The capability of MicroTrac could help to reduce the time-location uncertainty in air pollution exposure models and exposure metrics for individuals in health studies.

Transport of Aquatic Contaminant and Assessment of Radioecological Exposure with Spatial and Temporal Effects

Science.gov (United States)

Feng, Ying

1995-01-01

A comprehensive study of the radioecological exposure assessment for a contaminated aquatic ecosystem has been performed in this dissertation. The primary objectives of this research were to advance the understanding of radiation exposure in nature and to increase current capabilities for estimating aquatic radiation exposure with the consideration of spatial and temporal effect in nature. This was accomplished through the development of a two-dimensional aquatic exposure assessment framework and by applying the framework to the contaminated Chernobyl cooling lake (pond). This framework integrated spatial and temporal heterogeneity effects of contaminant concentration, abundance and distribution of ecosystem populations, spatial- and temporal-dependent (or density-dependent) radionuclide ingestion, and alternative food web structures. The exposure model was built on the population level to allow for the integration of density dependent population regulation into the exposure assessment. Plankton population dynamics have been integrated into the hydrodynamic-transport model to determine plankton biomass density changes and distributions. The distribution of contaminant in water was also calculated using a hydrodynamic-transport model. The significance of adding spatial and temporal effects, spatial and temporal related ecological functions, and hydrodynamics in the exposure assessment was illustrated through a series of case studies. The results suggested that the spatial and temporal heterogeneity effects of radioactive environments were substantial. Among the ecological functions considered, the food web structure was the most important contributor to the variations of fish exposure. The results obtained using a multiple prey food web structure differed by a factor of 20 from the equilibrium concentration, and by a factor of 2.5 from the concentration obtained using a single-prey food web. Impacts of changes in abundance and distribution of biomass on contaminant

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...

Assessing population exposures to motor vehicle exhaust.

Science.gov (United States)

Van Atten, Chris; Brauer, Michael; Funk, Tami; Gilbert, Nicolas L; Graham, Lisa; Kaden, Debra; Miller, Paul J; Bracho, Leonora Rojas; Wheeler, Amanda; White, Ronald H

2005-01-01

The need is growing for a better assessment of population exposures to motor vehicle exhaust in proximity to major roads and highways. This need is driven in part by emerging scientific evidence of adverse health effects from such exposures and policy requirements for a more targeted assessment of localized public health impacts related to road expansions and increasing commercial transportation. The momentum for improved methods in measuring local exposures is also growing in the scientific community, as well as for discerning which constituents of the vehicle exhaust mixture may exert greater public health risks for those who are exposed to a disproportionate share of roadway pollution. To help elucidate the current state-of-the-science in exposure assessments along major roadways and to help inform decision makers of research needs and trends, we provide an overview of the emerging policy requirements, along with a conceptual framework for assessing exposure to motor-vehicle exhaust that can help inform policy decisions. The framework includes the pathway from the emission of a single vehicle, traffic emissions from multiple vehicles, atmospheric transformation of emissions and interaction with topographic and meteorologic features, and contact with humans resulting in exposure that can result in adverse health impacts. We describe the individual elements within the conceptual framework for exposure assessment and discuss the strengths and weaknesses of various approaches that have been used to assess public exposures to motor vehicle exhaust.

In Vitro Exposure Systems and Dosimetry Assessment Tools ...

Science.gov (United States)

In 2009, the passing of The Family Smoking Prevention and Tobacco Control Act facilitated the establishment of the FDA Center for Tobacco Products (CTP) and gave it regulatory authority over the marketing, manufacture and distribution of tobacco products, including those termed “modified risk”. On 4-6 April 2016, the Institute for In Vitro Sciences, Inc. (IIVS) convened a workshop conference titled “In Vitro Exposure Systems and Dosimetry Assessment Tools for Inhaled Tobacco Products” to bring together stakeholders representing regulatory agencies, academia, and industry to address the research priorities articulated by the FDA CTP. Specific topics were covered to assess the status of current in vitro smoke and aerosol/vapor exposure systems, as well as the various approaches and challenges to quantifying the complex exposures, in in vitro pulmonary models developed for evaluating adverse pulmonary events resulting from tobacco product exposures. The four core topics covered were, 1) Tobacco Smoke And E-Cigarette Aerosols, 2) Air-Liquid Interface-In Vitro Exposure Systems, 3) Dosimetry Approaches For Particles And Vapors; In Vitro Dosimetry Determinations and 4) Exposure Microenvironment/Physiology Of Cells. The two and a half day workshop included presentations from 20 expert speakers, poster sessions, networking discussions, and breakout sessions which identified key findings and provided recommendations to advance these technologies. Here, we will re

Methyldibromo glutaronitrile: clinical experience and exposure-based risk assessment.

Science.gov (United States)

Zachariae, Claus; Rastogi, Suresh; Devantier, Charlotte; Menné, Torkil; Johansen, Jeanne Duus

2003-03-01

In the year 2000, the level of methyldibromo glutaronitrile (MDGN) allergy in dermatology clinics in Europe exceeded the level of allergies to all other preservatives, with a prevalence of 3.5%. In the present study, cases of primary sensitization and elicitation to MDGN due to cosmetic products were collected over an 8-month period at the Department of Dermatology, Gentofte University Hospital. The aim was to identify the products related to hand eczema, assess exposure to MDGN in these products and relate the findings to results from a newly developed updated risk assessment model for contact allergy. Out of 24 patients with a positive patch test to MDGN, 17 patients with hand eczema were identified. In 11 of these patients, cosmetic products used in relation to the onset of the disease were shown to contain MDGN (65%). In 8 of these 11 cases, primary sensitization was probable, 5 due to hand/body lotions and 3 due to lotions and/or liquid hand soap. Chemical analysis of 12 products showed that lotions contained 149-390 ppm of MDGN, liquid hand soap 144-399 ppm, a rinsing cream 293 ppm and shampoos 78-79 ppm. The shampoo exposure was not of certain relevance to the eczema. Applying the newly developed updated risk assessment model showed that the concentrations of MDGN in lotions of 149-390 ppm exceeded the calculated maximum acceptable exposure level for MDGN, which would be expected to lead to sensitization in consumers using such products, as seen in the current study. The present cases and updated exposure-based risk assessment process add to the evidence and need for re-defining safe-use concentrations of MDGN in cosmetic products.

Health effects assessment of chemical exposures: ARIES methodology

Energy Technology Data Exchange (ETDEWEB)

Sierra, L; Montero, M.; Rabago, I.; Vidania, R.

1995-07-01

In this work, we present ARIES* update: a system designed in order to facilitate the human health effects assessment produced by accidental release of toxic chemicals. The first version of ARIES was developed in relation to 82/501/EEC Directive about mayor accidents in the chemical industry. So, the first aim was the support of the effects assessment derived for the chemicals included into this directive. From this establishment, it was considered acute exposures for high concentrations. In this report, we present the actual methodology for considering other type of exposures, such as environmental and occupational. Likewise other versions, the methodology comprises two approaches: quantitative and qualitative assessments. Quantitative assessment incorporates the mathematical algorithms useful to evaluate the effects produced by the most important routes of exposure: inhalation, ingestion, eye contact and skin absorption, in a short, medium and long term. It has been included models that realizes an accurate quantification of doses, effects,... and so on, such as simple approaches when the available information is not enough. Qualitative assessment, designed in order to complement or replace the previous one, is incorporated into an informatics system, developed in Clipper. It executes and displays outstanding and important toxicological information of about 100 chemicals. This information comes from ECDIN (Environmental Chemicals Data and Information Network) database through a collaboration with JRC-ISPRA working group. (Author) 24 refs.

Health effects assessment of chemical exposures: ARIES methodology

International Nuclear Information System (INIS)

Sierra, L; Montero, M.; Rabago, I.; Vidania, R.

1995-01-01

In this work, we present ARIES* update: a system designed in order to facilitate the human health effects assessment produced by accidental release of toxic chemicals. The first version of ARIES was developed in relation to 82/501/EEC Directive about mayor accidents in the chemical industry. So, the first aim was the support of the effects assessment derived for the chemicals included into this directive. From this establishment, it was considered acute exposures for high concentrations. In this report, we present the actual methodology for considering other type of exposures, such as environmental and occupational. Likewise other versions, the methodology comprises two approaches: quantitative and qualitative assessments. Quantitative assessment incorporates the mathematical algorithms useful to evaluate the effects produced by the most important routes of exposure: inhalation, ingestion, eye contact and skin absorption, in a short, medium and long term. It has been included models that realizes an accurate quantification of doses, effects,... and so on, such as simple approaches when the available information is not enough. Qualitative assessment, designed in order to complement or replace the previous one, is incorporated into an informatics system, developed in Clipper. It executes and displays outstanding and important toxicological information of about 100 chemicals. This information comes from ECDIN (Environmental Chemicals Data and Information Network) database through a collaboration with JRC-ISPRA working group. (Author) 24 refs

Comprehensive European dietary exposure model (CEDEM) for food additives.

Science.gov (United States)

Tennant, David R

2016-05-01

European methods for assessing dietary exposures to nutrients, additives and other substances in food are limited by the availability of detailed food consumption data for all member states. A proposed comprehensive European dietary exposure model (CEDEM) applies summary data published by the European Food Safety Authority (EFSA) in a deterministic model based on an algorithm from the EFSA intake method for food additives. The proposed approach can predict estimates of food additive exposure provided in previous EFSA scientific opinions that were based on the full European food consumption database.

Use-exposure relationships of pesticides for aquatic risk assessment.

Directory of Open Access Journals (Sweden)

Yuzhou Luo

2011-04-01

Full Text Available Field-scale environmental models have been widely used in aquatic exposure assessments of pesticides. Those models usually require a large set of input parameters and separate simulations for each pesticide in evaluation. In this study, a simple use-exposure relationship is developed based on regression analysis of stochastic simulation results generated from the Pesticide Root-Zone Model (PRZM. The developed mathematical relationship estimates edge-of-field peak concentrations of pesticides from aerobic soil metabolism half-life (AERO, organic carbon-normalized soil sorption coefficient (KOC, and application rate (RATE. In a case study of California crop scenarios, the relationships explained 90-95% of the variances in the peak concentrations of dissolved pesticides as predicted by PRZM simulations for a 30-year period. KOC was identified as the governing parameter in determining the relative magnitudes of pesticide exposures in a given crop scenario. The results of model application also indicated that the effects of chemical fate processes such as partitioning and degradation on pesticide exposure were similar among crop scenarios, while the cross-scenario variations were mainly associated with the landscape characteristics, such as organic carbon contents and curve numbers. With a minimum set of input data, the use-exposure relationships proposed in this study could be used in screening procedures for potential water quality impacts from the off-site movement of pesticides.

Examining Exposure Assessment in Shift Work Research: A Study on Depression Among Nurses.

Science.gov (United States)

Hall, Amy L; Franche, Renée-Louise; Koehoorn, Mieke

2018-02-13

Coarse exposure assessment and assignment is a common issue facing epidemiological studies of shift work. Such measures ignore a number of exposure characteristics that may impact on health, increasing the likelihood of biased effect estimates and masked exposure-response relationships. To demonstrate the impacts of exposure assessment precision in shift work research, this study investigated relationships between work schedule and depression in a large survey of Canadian nurses. The Canadian 2005 National Survey of the Work and Health of Nurses provided the analytic sample (n = 11450). Relationships between work schedule and depression were assessed using logistic regression models with high, moderate, and low-precision exposure groupings. The high-precision grouping described shift timing and rotation frequency, the moderate-precision grouping described shift timing, and the low-precision grouping described the presence/absence of shift work. Final model estimates were adjusted for the potential confounding effects of demographic and work variables, and bootstrap weights were used to generate sampling variances that accounted for the survey sample design. The high-precision exposure grouping model showed the strongest relationships between work schedule and depression, with increased odds ratios [ORs] for rapidly rotating (OR = 1.51, 95% confidence interval [CI] = 0.91-2.51) and undefined rotating (OR = 1.67, 95% CI = 0.92-3.02) shift workers, and a decreased OR for depression in slow rotating (OR = 0.79, 95% CI = 0.57-1.08) shift workers. For the low- and moderate-precision exposure grouping models, weak relationships were observed for all work schedule categories (OR range 0.95 to 0.99). Findings from this study support the need to consider and collect the data required for precise and conceptually driven exposure assessment and assignment in future studies of shift work and health. Further research into the effects of shift rotation frequency on depression is

A Formaldehyde Exposure Assessment Tool for Occupants of FEMA Temporary Housing Units

Energy Technology Data Exchange (ETDEWEB)

Parthasarathy, Srinandini; Spears, Michael; Maddalena, Randy L.; Russell, Marion L; Apte, Michael G.

2010-10-01

The report outlines the methodology used to develop a web-based tool to assess the formaldehyde exposure of the occupants of Federal Emergency Management Administration (FEMA) temporary housing units (THUs) after Hurricanes Katrina and Rita in 2005. Linear regression models were built using available data to retrospectively estimate the indoor temperature and relative humidity, formaldehyde emission factors and concentration, and hence the formaldehyde exposures. The interactive web-tool allows the user to define the inputs to the model to evaluate formaldehyde exposures for different scenarios.

Statistical multi-path exposure method for assessing the whole-body SAR in a heterogeneous human body model in a realistic environment.

Science.gov (United States)

Vermeeren, Günter; Joseph, Wout; Martens, Luc

2013-04-01

Assessing the whole-body absorption in a human in a realistic environment requires a statistical approach covering all possible exposure situations. This article describes the development of a statistical multi-path exposure method for heterogeneous realistic human body models. The method is applied for the 6-year-old Virtual Family boy (VFB) exposed to the GSM downlink at 950 MHz. It is shown that the whole-body SAR does not differ significantly over the different environments at an operating frequency of 950 MHz. Furthermore, the whole-body SAR in the VFB for multi-path exposure exceeds the whole-body SAR for worst-case single-incident plane wave exposure by 3.6%. Moreover, the ICNIRP reference levels are not conservative with the basic restrictions in 0.3% of the exposure samples for the VFB at the GSM downlink of 950 MHz. The homogeneous spheroid with the dielectric properties of the head suggested by the IEC underestimates the absorption compared to realistic human body models. Moreover, the variation in the whole-body SAR for realistic human body models is larger than for homogeneous spheroid models. This is mainly due to the heterogeneity of the tissues and the irregular shape of the realistic human body model compared to homogeneous spheroid human body models. Copyright © 2012 Wiley Periodicals, Inc.

GPS-based microenvironment tracker (MicroTrac) model to estimate time–location of individuals for air pollution exposure assessments: Model evaluation in central North Carolina

Science.gov (United States)

Breen, Michael S.; Long, Thomas C.; Schultz, Bradley D.; Crooks, James; Breen, Miyuki; Langstaff, John E.; Isaacs, Kristin K.; Tan, Yu-Mei; Williams, Ronald W.; Cao, Ye; Geller, Andrew M.; Devlin, Robert B.; Batterman, Stuart A.; Buckley, Timothy J.

2014-01-01

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure to do so can add uncertainty and bias to risk estimates. In this study, a classification model, called MicroTrac, was developed to estimate time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from global positioning system (GPS) data and geocoded building boundaries. Based on a panel study, MicroTrac estimates were compared with 24-h diary data from nine participants, with corresponding GPS data and building boundaries of home, school, and work. MicroTrac correctly classified the ME for 99.5% of the daily time spent by the participants. The capability of MicroTrac could help to reduce the time–location uncertainty in air pollution exposure models and exposure metrics for individuals in health studies. PMID:24619294

Modeling Of In-Vehicle Human Exposure to Ambient Fine Particulate Matter

Science.gov (United States)

Liu, Xiaozhen; Frey, H. Christopher

2012-01-01

A method for estimating in-vehicle PM2.5 exposure as part of a scenario-based population simulation model is developed and assessed. In existing models, such as the Stochastic Exposure and Dose Simulation model for Particulate Matter (SHEDS-PM), in-vehicle exposure is estimated using linear regression based on area-wide ambient PM2.5 concentration. An alternative modeling approach is explored based on estimation of near-road PM2.5 concentration and an in-vehicle mass balance. Near-road PM2.5 concentration is estimated using a dispersion model and fixed site monitor (FSM) data. In-vehicle concentration is estimated based on air exchange rate and filter efficiency. In-vehicle concentration varies with road type, traffic flow, windspeed, stability class, and ventilation. Average in-vehicle exposure is estimated to contribute 10 to 20 percent of average daily exposure. The contribution of in-vehicle exposure to total daily exposure can be higher for some individuals. Recommendations are made for updating exposure models and implementation of the alternative approach. PMID:23101000

Modeled exposure assessment via inhalation and dermal pathways to airborne semivolatile organic compounds (SVOCs) in residences.

Science.gov (United States)

Shi, Shanshan; Zhao, Bin

2014-05-20

Exposure to airborne semivolatile organic compounds (SVOCs) in indoor and outdoor environments of humans may lead to adverse health risks. Thus, we established a model to evaluate exposure to airborne SVOCs. In this model, SVOCs phase-specific concentrations were estimated by a kinetic partition model accounting for particle dynamics. The exposure pathways to airborne SVOCs included inhalation exposure to gas- and particle-phases, dermal exposure by direct gas-to-skin pathway and dermal exposure by direct particle deposition. Exposures of defined "reference people" to two typical classifications of SVOCs, one generated from both indoor and outdoor sources, represented by polycyclic aromatic hydrocarbons (PAHs), and the other generated mainly from only indoor sources, represented by di 2-ethylhexyl phthalate (DEHP), were analyzed as an example application of the model. For PAHs with higher volatility, inhalation exposure to gas-phase, ranging from 6.03 to 16.4 ng/kg/d, accounted for the most of the exposure to the airborne phases. For PAHs with lower volatility, inhalation exposure to particle-phase, ranging from 1.48 to 1.53 ng/kg/d, was the most important exposure pathway. As for DEHP, dermal exposure via direct gas-to-skin pathway was 460 ng/kg/d, which was the most striking exposure pathway when the barrier effect of clothing was neglected.

Range-finding risk assessment of inhalation exposure to nanodiamonds in a laboratory environment.

Science.gov (United States)

Koivisto, Antti J; Palomäki, Jaana E; Viitanen, Anna-Kaisa; Siivola, Kirsi M; Koponen, Ismo K; Yu, Mingzhou; Kanerva, Tomi S; Norppa, Hannu; Alenius, Harri T; Hussein, Tareq; Savolainen, Kai M; Hämeri, Kaarle J

2014-05-16

This study considers fundamental methods in occupational risk assessment of exposure to airborne engineered nanomaterials. We discuss characterization of particle emissions, exposure assessment, hazard assessment with in vitro studies, and risk range characterization using calculated inhaled doses and dose-response translated to humans from in vitro studies. Here, the methods were utilized to assess workers' risk range of inhalation exposure to nanodiamonds (NDs) during handling and sieving of ND powder. NDs were agglomerated to over 500 nm particles, and mean exposure levels of different work tasks varied from 0.24 to 4.96 µg·m(-3) (0.08 to 0.74 cm(-3)). In vitro-experiments suggested that ND exposure may cause a risk for activation of inflammatory cascade. However, risk range characterization based on in vitro dose-response was not performed because accurate assessment of delivered (settled) dose on the cells was not possible. Comparison of ND exposure with common pollutants revealed that ND exposure was below 5 μg·m(-3), which is one of the proposed exposure limits for diesel particulate matter, and the workers' calculated dose of NDs during the measurement day was 74 ng which corresponded to 0.02% of the modeled daily (24 h) dose of submicrometer urban air particles.

Range-Finding Risk Assessment of Inhalation Exposure to Nanodiamonds in a Laboratory Environment

Directory of Open Access Journals (Sweden)

Antti J. Koivisto

2014-05-01

Full Text Available This study considers fundamental methods in occupational risk assessment of exposure to airborne engineered nanomaterials. We discuss characterization of particle emissions, exposure assessment, hazard assessment with in vitro studies, and risk range characterization using calculated inhaled doses and dose-response translated to humans from in vitro studies. Here, the methods were utilized to assess workers’ risk range of inhalation exposure to nanodiamonds (NDs during handling and sieving of ND powder. NDs were agglomerated to over 500 nm particles, and mean exposure levels of different work tasks varied from 0.24 to 4.96 µg·m−3 (0.08 to 0.74 cm−3. In vitro-experiments suggested that ND exposure may cause a risk for activation of inflammatory cascade. However, risk range characterization based on in vitro dose-response was not performed because accurate assessment of delivered (settled dose on the cells was not possible. Comparison of ND exposure with common pollutants revealed that ND exposure was below 5 μg·m−3, which is one of the proposed exposure limits for diesel particulate matter, and the workers’ calculated dose of NDs during the measurement day was 74 ng which corresponded to 0.02% of the modeled daily (24 h dose of submicrometer urban air particles.

Models for Pesticide Risk Assessment

Science.gov (United States)

EPA considers the toxicity of the pesticide as well as the amount of pesticide to which a person or the environments may be exposed in risk assessment. Scientists use mathematical models to predict pesticide concentrations in exposure assessment.

How to assess exposure of aquatic organisms to manufactured nanoparticles?

DEFF Research Database (Denmark)

Quik, Joris T.K.; Vonk, Jan Arie; Hansen, Steffen Foss

2011-01-01

Ecological risk of chemicals is measured by the quotient of predicted no-effect concentrations and predicted exposure concentrations, which are hard to assess for manufactured nanomaterials (NMs). This paper proposes modifications to currently used models, in order to make them suitable for estim......Ecological risk of chemicals is measured by the quotient of predicted no-effect concentrations and predicted exposure concentrations, which are hard to assess for manufactured nanomaterials (NMs). This paper proposes modifications to currently used models, in order to make them suitable...... on sedimentation and dissolution of NMs in environmentally relevant systems. We deduce that the overall kinetics of water–sediment transport of NMs should be close to first order. The lack of data on dissolution of NMs under environmentally realistic conditions calls for a pragmatic decision on which rates...

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.

EPa`s program for risk assessment guidelines: Exposure issues

Energy Technology Data Exchange (ETDEWEB)

Callahan, M.A. [Environmental Protection Agency, Washington, DC (United States)

1990-12-31

Three major issues to be dealt with over the next ten years in the exposure assessment field are: consistency in terminology, the impact of computer technology on the choice of data and modeling, and conceptual issues such as the use of time-weighted averages.

Sensitivity Analysis of Personal Exposure Assessment Using a Computer Simulated Person

DEFF Research Database (Denmark)

Brohus, Henrik; Jensen, H. K.

2009-01-01

The paper considers uncertainties related to personal exposure assessment using a computer simulated person. CFD is used to simulate a uniform flow field around a human being to determine the personal exposure to a contaminant source. For various vertical locations of a point contaminant source...... three additional factors are varied, namely the velocity, details of the computer simulated person, and the CFD model of the wind channel. The personal exposure is found to be highly dependent on the relative source location. Variation in the range of two orders of magnitude is found. The exposure...

Exposure assessment in studies on health effects of traffic exhaust

Energy Technology Data Exchange (ETDEWEB)

Setaelae, S. [Association for the Pulmonary Disabled, Helsinki (Finland); Jaakkola, J.J.K. [Helsinki Univ. (Finland). Dept. of Public Health

1995-12-31

A main source of outdoor air pollution is road traffic, which produces a complex mixture of nitrogen oxides, carbon monoxide, volatile hydrocarbons, airborne particles and some other compounds. Traffic exhaust affects also the concentrations of ozone and other photo chemical oxidants. In earlier studies those components have had remarkable health effects. Several studies on occupational exposure to automobile exhaust have been published and several studies have been observed an association between both outdoor and indoor pollutant levels and health outcomes. However, there are only a few epidemiological studies in which traffic exhaust, a complex mixture, has been studied in its entirety. During recent years, interesting epidemiological studies of the health effects of this complex mixture have been published. Human exposure assessment for traffic exhaust can be categorized according to the environment of exposure (indoors, outdoors, in-traffic) or to the method of exposure assessment (direct or indirect methods). In this presentation the methods are further categorized into (1) traffic activity, (2) air concentration measurements, and (3) dispersion models, in order to better understand the advantages and disadvantages of different approaches. The objective of this presentation is to make a critical review of exposure assessments in the epidemiological studies on health effects of traffic exhaust. (author)

Exposure assessment in studies on health effects of traffic exhaust

Energy Technology Data Exchange (ETDEWEB)

Setaelae, S [Association for the Pulmonary Disabled, Helsinki (Finland); Jaakkola, J J.K. [Helsinki Univ. (Finland). Dept. of Public Health

1996-12-31

A main source of outdoor air pollution is road traffic, which produces a complex mixture of nitrogen oxides, carbon monoxide, volatile hydrocarbons, airborne particles and some other compounds. Traffic exhaust affects also the concentrations of ozone and other photo chemical oxidants. In earlier studies those components have had remarkable health effects. Several studies on occupational exposure to automobile exhaust have been published and several studies have been observed an association between both outdoor and indoor pollutant levels and health outcomes. However, there are only a few epidemiological studies in which traffic exhaust, a complex mixture, has been studied in its entirety. During recent years, interesting epidemiological studies of the health effects of this complex mixture have been published. Human exposure assessment for traffic exhaust can be categorized according to the environment of exposure (indoors, outdoors, in-traffic) or to the method of exposure assessment (direct or indirect methods). In this presentation the methods are further categorized into (1) traffic activity, (2) air concentration measurements, and (3) dispersion models, in order to better understand the advantages and disadvantages of different approaches. The objective of this presentation is to make a critical review of exposure assessments in the epidemiological studies on health effects of traffic exhaust. (author)

The Diesel Exhaust in Miners Study: I. Overview of the Exposure Assessment Process

Science.gov (United States)

Stewart, Patricia A.; Coble, Joseph B.; Vermeulen, Roel; Schleiff, Patricia; Blair, Aaron; Lubin, Jay; Attfield, Michael; Silverman, Debra T.

2010-01-01

This report provides an overview of the exposure assessment process for an epidemiologic study that investigated mortality, with a special focus on lung cancer, associated with diesel exhaust (DE) exposure among miners. Details of several components are provided in four other reports. A major challenge for this study was the development of quantitative estimates of historical exposures to DE. There is no single standard method for assessing the totality of DE, so respirable elemental carbon (REC), a component of DE, was selected as the primary surrogate in this study. Air monitoring surveys at seven of the eight study mining facilities were conducted between 1998 and 2001 and provided reference personal REC exposure levels and measurements for other agents and DE components in the mining environment. (The eighth facility had closed permanently prior to the surveys.) Exposure estimates were developed for mining facility/department/job/year combinations. A hierarchical grouping strategy was developed for assigning exposure levels to underground jobs [based on job titles, on the amount of time spent in various areas of the underground mine, and on similar carbon monoxide (CO, another DE component) concentrations] and to surface jobs (based on the use of, or proximity to, diesel-powered equipment). Time trends in air concentrations for underground jobs were estimated from mining facility-specific prediction models using diesel equipment horsepower, total air flow rates exhausted from the underground mines, and, because there were no historical REC measurements, historical measurements of CO. Exposures to potentially confounding agents, i.e. respirable dust, silica, radon, asbestos, and non-diesel sources of polycyclic aromatic hydrocarbons, also were assessed. Accuracy and reliability of the estimated REC exposures levels were evaluated by comparison with several smaller datasets and by development of alternative time trend models. During 1998–2001, the average

A Realistic Human Exposure Assessment of Indoor Radon released from Groundwater

International Nuclear Information System (INIS)

Yu, Dong Han; Han, Moon Hee

2002-01-01

The work presents a realistic human exposure assessment of indoor radon released from groundwater in a house. At first, a two-compartment model is developed to describe the generation and transfer of radon in indoor air from groundwater. The model is used to estimate radon concentrations profile of indoor air in a house using by showering, washing clothes, and flushing toilets. Then, the study performs an uncertainty analysis of model input parameters to quantify the uncertainty in radon concentration profile. In order to estimate a daily internal dose of a specific tissue group in an adult through the inhalation of such indoor radon, a PBPK(Physiologically-Based Pharmaco-Kinetic) model is developed. Combining indoor radon profile and PBPK model is used to a realistic human assessment for such exposure. The results obtained from this study would be used to the evaluation of human risk by inhalation associated with the indoor radon released from groundwater

Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models.

Science.gov (United States)

Teng, S; Tebby, C; Barcellini-Couget, S; De Sousa, G; Brochot, C; Rahmani, R; Pery, A R R

2016-08-15

Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro - in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-time cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds. Copyright © 2016 Elsevier Inc. All rights reserved.

Application of Physiologically Based Pharmacokinetic Models in Chemical Risk Assessment

Directory of Open Access Journals (Sweden)

Moiz Mumtaz

2012-01-01

Full Text Available Post-exposure risk assessment of chemical and environmental stressors is a public health challenge. Linking exposure to health outcomes is a 4-step process: exposure assessment, hazard identification, dose response assessment, and risk characterization. This process is increasingly adopting “in silico” tools such as physiologically based pharmacokinetic (PBPK models to fine-tune exposure assessments and determine internal doses in target organs/tissues. Many excellent PBPK models have been developed. But most, because of their scientific sophistication, have found limited field application—health assessors rarely use them. Over the years, government agencies, stakeholders/partners, and the scientific community have attempted to use these models or their underlying principles in combination with other practical procedures. During the past two decades, through cooperative agreements and contracts at several research and higher education institutions, ATSDR funded translational research has encouraged the use of various types of models. Such collaborative efforts have led to the development and use of transparent and user-friendly models. The “human PBPK model toolkit” is one such project. While not necessarily state of the art, this toolkit is sufficiently accurate for screening purposes. Highlighted in this paper are some selected examples of environmental and occupational exposure assessments of chemicals and their mixtures.

A review of models for near-field exposure pathways of chemicals in consumer products

DEFF Research Database (Denmark)

Huang, Lei; Ernstoff, Alexi; Fantke, Peter

2017-01-01

able to quantify the multiple transfers of chemicals from products used near-field to humans. The present review therefore aims at an in-depth overview of modeling approaches for near-field chemical release and human exposure pathways associated with consumer products. It focuses on lower......-tier, mechanistic models suitable for life cycle assessments (LCA), chemical alternative assessment (CAA) and high-throughput screening risk assessment (HTS). Chemicals in a product enter the near-field via a defined “compartment of entry”, are transformed or transferred to adjacent compartments, and eventually end......Exposure to chemicals in consumer products has been gaining increasing attention, with multiple studies showing that near-field exposures from products is high compared to far-field exposures. Regarding the numerous chemical-product combinations, there is a need for an overarching review of models...

Assessing radiological impacts (exposures and doses) associated with the mining and milling of radioactive ores

International Nuclear Information System (INIS)

Williams, G.A.

1990-01-01

The basic units and concepts applicable to radiological assessment are presented. Data relevant to the assessment of radiological exposures from the mining and milling phases of uranium and thorium ores are discussed. As a guide to the assessment of environmental exposures to members of the public, concepts such as the critical group are defined. Environmental transport and exposure pathways are presented in general terms, together with a discussion of the use of mathematical models. The dose assessment procedures defined in the 1987 Code of Practice are described. 13 refs., 2 tabs., 1 fig

A probabilistic assessment of health risks associated with short-term exposure to tropospheric ozone

Energy Technology Data Exchange (ETDEWEB)

Whitfield, R.G; Biller, W.F.; Jusko, M.J.; Keisler, J.M.

1996-06-01

The work described in this report is part of a larger risk assessment sponsored by the U.S. Environmental Protection Agency. Earlier efforts developed exposure-response relationships for acute health effects among populations engaged in heavy exertion. Those efforts also developed a probabilistic national ambient air quality standards exposure model and a general methodology for integrating probabilistic exposure-response relation- ships and exposure estimates to calculate overall risk results. Recently published data make it possible to model additional health endpoints (for exposure at moderate exertion), including hospital admissions. New air quality and exposure estimates for alternative national ambient air quality standards for ozone are combined with exposure-response models to produce the risk results for hospital admissions and acute health effects. Sample results explain the methodology and introduce risk output formats.

Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models

International Nuclear Information System (INIS)

Teng, S.; Tebby, C.; Barcellini-Couget, S.; De Sousa, G.; Brochot, C.; Rahmani, R.; Pery, A.R.R.

2016-01-01

Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro – in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-time cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds. - Highlights: • We could predict cell response over repeated exposure to mixtures of cosmetics. • Compounds acted independently on the cells. • Metabolic interactions impacted exposure concentrations to the compounds.

Analysis of real-time mixture cytotoxicity data following repeated exposure using BK/TD models

Energy Technology Data Exchange (ETDEWEB)

Teng, S.; Tebby, C. [Models for Toxicology and Ecotoxicology Unit, INERIS, Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France); Barcellini-Couget, S. [ODESIA Neosciences, Sophia Antipolis, 400 route des chappes, 06903 Sophia Antipolis (France); De Sousa, G. [INRA, ToxAlim, 400 route des Chappes, BP, 167 06903 Sophia Antipolis, Cedex (France); Brochot, C. [Models for Toxicology and Ecotoxicology Unit, INERIS, Parc Technologique Alata, BP 2, 60550 Verneuil-en-Halatte (France); Rahmani, R. [INRA, ToxAlim, 400 route des Chappes, BP, 167 06903 Sophia Antipolis, Cedex (France); Pery, A.R.R., E-mail: alexandre.pery@agroparistech.fr [AgroParisTech, UMR 1402 INRA-AgroParisTech Ecosys, 78850 Thiverval Grignon (France); INRA, UMR 1402 INRA-AgroParisTech Ecosys, 78850 Thiverval Grignon (France)

2016-08-15

Cosmetic products generally consist of multiple ingredients. Thus, cosmetic risk assessment has to deal with mixture toxicity on a long-term scale which means it has to be assessed in the context of repeated exposure. Given that animal testing has been banned for cosmetics risk assessment, in vitro assays allowing long-term repeated exposure and adapted for in vitro – in vivo extrapolation need to be developed. However, most in vitro tests only assess short-term effects and consider static endpoints which hinder extrapolation to realistic human exposure scenarios where concentration in target organs is varies over time. Thanks to impedance metrics, real-time cell viability monitoring for repeated exposure has become possible. We recently constructed biokinetic/toxicodynamic models (BK/TD) to analyze such data (Teng et al., 2015) for three hepatotoxic cosmetic ingredients: coumarin, isoeugenol and benzophenone-2. In the present study, we aim to apply these models to analyze the dynamics of mixture impedance data using the concepts of concentration addition and independent action. Metabolic interactions between the mixture components were investigated, characterized and implemented in the models, as they impacted the actual cellular exposure. Indeed, cellular metabolism following mixture exposure induced a quick disappearance of the compounds from the exposure system. We showed that isoeugenol substantially decreased the metabolism of benzophenone-2, reducing the disappearance of this compound and enhancing its in vitro toxicity. Apart from this metabolic interaction, no mixtures showed any interaction, and all binary mixtures were successfully modeled by at least one model based on exposure to the individual compounds. - Highlights: • We could predict cell response over repeated exposure to mixtures of cosmetics. • Compounds acted independently on the cells. • Metabolic interactions impacted exposure concentrations to the compounds.

How Exposure Science can be Integrated into the Assessment ...

Science.gov (United States)

The presentation describes ongoing research in the Rapid Exposure and Dosimetry project funded under the Chemical Safety for Sustainability Research Program of the Office of Research and Development. There is a well known need for information on human exposure to thousands of chemicals, especially with respect to route of exposure. A combination of curation of legacy data, new data collection activities, and mathematical models based both upon statistics (empirical) and mechanism are allowing chemicals to be prioritized for further exposure study. This presentation pays special attention to the opportunities presented by non-targeted screening using mass spectrometry. This is a presentation to the American College of Toxicology annual meeting in Baltimore, Maryland on November 7, 2016. This half hour presentation is part of a session on 21st Century Approaches to Assessing Food Ingredient Safety.

Validation of the dermal exposure model in ECETOC TRA.

Science.gov (United States)

Marquart, Hans; Franken, Remy; Goede, Henk; Fransman, Wouter; Schinkel, Jody

2017-08-01

The ECETOC TRA model (presently version 3.1) is often used to estimate worker inhalation and dermal exposure in regulatory risk assessment. The dermal model in ECETOC TRA has not yet been validated by comparison with independent measured exposure levels. This was the goal of the present study. Measured exposure levels and relevant contextual information were gathered via literature search, websites of relevant occupational health institutes and direct requests for data to industry. Exposure data were clustered in so-called exposure cases, which are sets of data from one data source that are expected to have the same values for input parameters in the ECETOC TRA dermal exposure model. For each exposure case, the 75th percentile of measured values was calculated, because the model intends to estimate these values. The input values for the parameters in ECETOC TRA were assigned by an expert elicitation and consensus building process, based on descriptions of relevant contextual information.From more than 35 data sources, 106 useful exposure cases were derived, that were used for direct comparison with the model estimates. The exposure cases covered a large part of the ECETOC TRA dermal exposure model. The model explained 37% of the variance in the 75th percentiles of measured values. In around 80% of the exposure cases, the model estimate was higher than the 75th percentile of measured values. In the remaining exposure cases, the model estimate may not be sufficiently conservative.The model was shown to have a clear bias towards (severe) overestimation of dermal exposure at low measured exposure values, while all cases of apparent underestimation by the ECETOC TRA dermal exposure model occurred at high measured exposure values. This can be partly explained by a built-in bias in the effect of concentration of substance in product used, duration of exposure and the use of protective gloves in the model. The effect of protective gloves was calculated to be on average a

Radiation transport modeling and assessment to better predict radiation exposure, dose, and toxicological effects to human organs on long duration space flights

Science.gov (United States)

Denkins, P.; Badhwar, G.; Obot, V.; Wilson, B.; Jejelewo, O.

2001-01-01

NASA is very interested in improving its ability to monitor and forecast the radiation levels that pose a health risk to space-walking astronauts as they construct the International Space Station and astronauts that will participate in long-term and deep-space missions. Human exploratory missions to the moon and Mars within the next quarter century, will expose crews to transient radiation from solar particle events which include high-energy galactic cosmic rays and high-energy protons. Because the radiation levels in space are high and solar activity is presently unpredictable, adequate shielding is needed to minimize the deleterious health effects of exposure to radiation. Today, numerous models have been developed and used to predict radiation exposure. Such a model is the Space Environment Information Systems (SPENVIS) modeling program, developed by the Belgian Institute for Space Aeronautics. SPENVIS, which has been assessed to be an excellent tool in characterizing the radiation environment for microelectronics and investigating orbital debris, is being evaluated for its usefulness with determining the dose and dose-equivalent for human exposure. Thus far. the calculations for dose-depth relations under varying shielding conditions have been in agreement with calculations done using HZETRN and PDOSE, which are well-known and widely used models for characterizing the environments for human exploratory missions. There is disagreement when assessing the impact of secondary radiation particles since SPENVIS does a crude estimation of the secondary radiation particles when calculating LET versus Flux. SPENVIS was used to model dose-depth relations for the blood-forming organs. Radiation sickness and cancer are life-threatening consequences resulting from radiation exposure. In space. exposure to radiation generally includes all of the critical organs. Biological and toxicological impacts have been included for discussion along with alternative risk mitigation

Radiation transport modeling and assessment to better predict radiation exposure, dose, and toxicological effects to human organs on long duration space flights

Science.gov (United States)

Denkins, Pamela; Badhwar, Gautam; Obot, Victor; Wilson, Bobby; Jejelewo, Olufisayo

2001-08-01

NASA is very interested in improving its ability to monitor and forecast the radiation levels that pose a health risk to space-walking astronauts as they construct the International Space Station and astronauts that will participate in long-term and deep-space missions. Human exploratory missions to the moon and Mars within the next quarter century, will expose crews to transient radiation from solar particle events which include high-energy galactic cosmic rays and high-energy protons. Because the radiation levels in space are high and solar activity is presently unpredictable, adequate shielding is needed to minimize the deleterious health effects of exposure to radiation. Today, numerous models have been developed and used to predict radiation exposure. Such a model is the Space Environment Information Systems (SPENVIS) modeling program, developed by the Belgian Institute for Space Aeronautics. SPENVIS, which has been assessed to be an excellent tool in characterizing the radiation environment for microelectronics and investigating orbital debris, is being evaluated for its usefulness with determining the dose and dose-equivalent for human exposure. Thus far, the calculations for dose-depth relations under varying shielding conditions have been in agreement with calculations done using HZETRN and PDOSE, which are well-known and widely used models for characterizing the environments for human exploratory missions. There is disagreement when assessing the impact of secondary radiation particles since SPENVIS does a crude estimation of the secondary radiation particles when calculating LET versus Flux. SPENVIS was used to model dose-depth relations for the blood-forming organs. Radiation sickness and cancer are life-threatening consequences resulting from radiation exposure. In space, exposure to radiation generally includes all of the critical organs. Biological and toxicological impacts have been included for discussion along with alternative risk mitigation

Probabilistic mercury multimedia exposure assessment in small children and risk assessment.

Science.gov (United States)

Morisset, Typhaine; Ramirez-Martinez, Alejandra; Wesolek, Nathalie; Roudot, Alain-Claude

2013-09-01

Emissions of mercury in the environment have been decreasing for several years. However, mercury species are still found in different media (food, water, air and breast-milk). Due to mercury toxicity and typical behaviour in children, we have conducted a mercury exposure assessment in French babies, and small children aged 0 to 36months. Consumption and mercury concentration data were chosen for the exposure assessment. The Monte Carlo technique has been used to calculate the weekly exposure dose in order to integrate inter-individual variability and parameter uncertainty. Exposure values have been compared to toxicological reference values for health risk assessment. Inorganic mercury median exposure levels ranged from 0.160 to 1.649μg/kg of body weight per week (95th percentile (P95): 0.298-2.027µg/kg bw/week); elemental mercury median exposure level in children was 0.11ng/kg bw/week (P95: 28ng/kg bw/week); and methylmercury median exposure level ranged from 0.247 to 0.273µg/kg bw/week (P95: 0.425-0.463µg/kg bw/week). Only elemental mercury by inhalation route (indoor air) and methylmercury by ingestion (fish and breast-milk) seem to lead to a health risk in small children. These results confirm the importance of assessing total mercury concentration in media like breast-milk, indoor air and dust and methylmercury level in food, other than fish and seafood. In this way, informed monitoring plan and risk assessment in an at-risk sub-population can be set. © 2013 Elsevier Ltd. All rights reserved.

Analysis of intervention strategies for inhalation exposure to polycyclic aromatic hydrocarbons and associated lung cancer risk based on a Monte Carlo population exposure assessment model.

Science.gov (United States)

Zhou, Bin; Zhao, Bin

2014-01-01

It is difficult to evaluate and compare interventions for reducing exposure to air pollutants, including polycyclic aromatic hydrocarbons (PAHs), a widely found air pollutant in both indoor and outdoor air. This study presents the first application of the Monte Carlo population exposure assessment model to quantify the effects of different intervention strategies on inhalation exposure to PAHs and the associated lung cancer risk. The method was applied to the population in Beijing, China, in the year 2006. Several intervention strategies were designed and studied, including atmospheric cleaning, smoking prohibition indoors, use of clean fuel for cooking, enhancing ventilation while cooking and use of indoor cleaners. Their performances were quantified by population attributable fraction (PAF) and potential impact fraction (PIF) of lung cancer risk, and the changes in indoor PAH concentrations and annual inhalation doses were also calculated and compared. The results showed that atmospheric cleaning and use of indoor cleaners were the two most effective interventions. The sensitivity analysis showed that several input parameters had major influence on the modeled PAH inhalation exposure and the rankings of different interventions. The ranking was reasonably robust for the remaining majority of parameters. The method itself can be extended to other pollutants and in different places. It enables the quantitative comparison of different intervention strategies and would benefit intervention design and relevant policy making.

Analysis of intervention strategies for inhalation exposure to polycyclic aromatic hydrocarbons and associated lung cancer risk based on a Monte Carlo population exposure assessment model.

Directory of Open Access Journals (Sweden)

Bin Zhou

Full Text Available It is difficult to evaluate and compare interventions for reducing exposure to air pollutants, including polycyclic aromatic hydrocarbons (PAHs, a widely found air pollutant in both indoor and outdoor air. This study presents the first application of the Monte Carlo population exposure assessment model to quantify the effects of different intervention strategies on inhalation exposure to PAHs and the associated lung cancer risk. The method was applied to the population in Beijing, China, in the year 2006. Several intervention strategies were designed and studied, including atmospheric cleaning, smoking prohibition indoors, use of clean fuel for cooking, enhancing ventilation while cooking and use of indoor cleaners. Their performances were quantified by population attributable fraction (PAF and potential impact fraction (PIF of lung cancer risk, and the changes in indoor PAH concentrations and annual inhalation doses were also calculated and compared. The results showed that atmospheric cleaning and use of indoor cleaners were the two most effective interventions. The sensitivity analysis showed that several input parameters had major influence on the modeled PAH inhalation exposure and the rankings of different interventions. The ranking was reasonably robust for the remaining majority of parameters. The method itself can be extended to other pollutants and in different places. It enables the quantitative comparison of different intervention strategies and would benefit intervention design and relevant policy making.

A Comparison of Two Strategies for Building an Exposure Prediction Model.

Science.gov (United States)

Heiden, Marina; Mathiassen, Svend Erik; Garza, Jennifer; Liv, Per; Wahlström, Jens

2016-01-01

Cost-efficient assessments of job exposures in large populations may be obtained from models in which 'true' exposures assessed by expensive measurement methods are estimated from easily accessible and cheap predictors. Typically, the models are built on the basis of a validation study comprising 'true' exposure data as well as an extensive collection of candidate predictors from questionnaires or company data, which cannot all be included in the models due to restrictions in the degrees of freedom available for modeling. In these situations, predictors need to be selected using procedures that can identify the best possible subset of predictors among the candidates. The present study compares two strategies for selecting a set of predictor variables. One strategy relies on stepwise hypothesis testing of associations between predictors and exposure, while the other uses cluster analysis to reduce the number of predictors without relying on empirical information about the measured exposure. Both strategies were applied to the same dataset on biomechanical exposure and candidate predictors among computer users, and they were compared in terms of identified predictors of exposure as well as the resulting model fit using bootstrapped resamples of the original data. The identified predictors were, to a large part, different between the two strategies, and the initial model fit was better for the stepwise testing strategy than for the clustering approach. Internal validation of the models using bootstrap resampling with fixed predictors revealed an equally reduced model fit in resampled datasets for both strategies. However, when predictor selection was incorporated in the validation procedure for the stepwise testing strategy, the model fit was reduced to the extent that both strategies showed similar model fit. Thus, the two strategies would both be expected to perform poorly with respect to predicting biomechanical exposure in other samples of computer users. © The

Population models for time-varying pesticide exposure

NARCIS (Netherlands)

Jager T; Jong FMW de; Traas TP; LER; SEC

2007-01-01

A model has recently been developed at RIVM to predict the effects of variable exposure to pesticides of plant and animal populations in surface water. Before a pesticide is placed on the market, the environmental risk of the substance has to be assessed. This risk is estimated by comparing

Underwater Sound Propagation Modeling Methods for Predicting Marine Animal Exposure.

Science.gov (United States)

Hamm, Craig A; McCammon, Diana F; Taillefer, Martin L

2016-01-01

The offshore exploration and production (E&P) industry requires comprehensive and accurate ocean acoustic models for determining the exposure of marine life to the high levels of sound used in seismic surveys and other E&P activities. This paper reviews the types of acoustic models most useful for predicting the propagation of undersea noise sources and describes current exposure models. The severe problems caused by model sensitivity to the uncertainty in the environment are highlighted to support the conclusion that it is vital that risk assessments include transmission loss estimates with statistical measures of confidence.

Modeling and Characterization of the Uplink and Downlink Exposure in Wireless Networks

Directory of Open Access Journals (Sweden)

Anis Krayni

2017-01-01

Full Text Available This paper deals with a new methodology to assess the exposure induced by both uplink and downlink of a cellular network using 3D electromagnetic simulations. It aims to analyze together the exposure induced by a personal device (uplink exposure and that induced by a base station (downlink exposure. The study involved the major parameters contributing to variability and uncertainty in exposure assessment, such as the user’s posture, the type of wireless device, and the propagation environment. Our approach is relying basically on the modeling of the power radiated by the personal device and the ambient electric field, while taking into account the effects of human body shadowing and the propagation channel fluctuations. The exposure assessment as well as the human-wave interactions has been simulated using the finite difference in time domain method (FDTD. In uplink scenarios, four FDTD simulations were performed with a child model, used in two postures (sitting and standing and in two usage scenarios (voice and data, which aimed to examine the exposure induced by a mobile phone and a tablet emitting, respectively, at 900 MHz and 1940 MHz. In the downlink scenario, a series of FDTD simulations of an exposure to a single plane wave and multiplane waves have been conducted, and an efficient metamodeling of the exposure using the Polynomial Chaos approach has been developed.

Modeling exposure to air pollution and cardiovascular mortality: the ESCAPE study

NARCIS (Netherlands)

Wang, M.|info:eu-repo/dai/nl/345480279

2013-01-01

Exposure assessment is one of the key issues for health effect estimates in environmental epidemiology. Recent interest has increased in exposure modeling incorporating Geographic Information System (GIS) data to capture small-scale spatial variability in air pollution concentrations. Land use

Traffic-Related Air Pollution and Childhood Asthma: Recent Advances and Remaining Gaps in the Exposure Assessment Methods.

Science.gov (United States)

Khreis, Haneen; Nieuwenhuijsen, Mark J

2017-03-17

Background : Current levels of traffic-related air pollution (TRAP) are associated with the development of childhood asthma, although some inconsistencies and heterogeneity remain. An important part of the uncertainty in studies of TRAP-associated asthma originates from uncertainties in the TRAP exposure assessment and assignment methods. In this work, we aim to systematically review the exposure assessment methods used in the epidemiology of TRAP and childhood asthma, highlight recent advances, remaining research gaps and make suggestions for further research. Methods : We systematically reviewed epidemiological studies published up until 8 September 2016 and available in Embase, Ovid MEDLINE (R), and "Transport database". We included studies which examined the association between children's exposure to TRAP metrics and their risk of "asthma" incidence or lifetime prevalence, from birth to the age of 18 years old. Results : We found 42 studies which examined the associations between TRAP and subsequent childhood asthma incidence or lifetime prevalence, published since 1999. Land-use regression modelling was the most commonly used method and nitrogen dioxide (NO₂) was the most commonly used pollutant in the exposure assessments. Most studies estimated TRAP exposure at the residential address and only a few considered the participants' mobility. TRAP exposure was mostly assessed at the birth year and only a few studies considered different and/or multiple exposure time windows. We recommend that further work is needed including e.g., the use of new exposure metrics such as the composition of particulate matter, oxidative potential and ultra-fine particles, improved modelling e.g., by combining different exposure assessment models, including mobility of the participants, and systematically investigating different exposure time windows. Conclusions : Although our previous meta-analysis found statistically significant associations for various TRAP exposures and

Human exposure assessment to environmental chemicals using biomonitoring.

Science.gov (United States)

Calafat, Antonia M; Ye, Xiaoyun; Silva, Manori J; Kuklenyik, Zsuzsanna; Needham, Larry L

2006-02-01

In modern societies, humans may be exposed to a wide spectrum of environmental chemicals. Although the health significance of this exposure for many chemicals is unknown, studies to investigate the prevalence of exposure are warranted because of the chemicals' potential harmful health effects, as often indicated in animal studies. Three tools have been used to assess exposure: exposure history/questionnaire information, environmental monitoring, and biomonitoring (i.e. measuring concentrations of the chemicals, their metabolites, or their adducts in human specimens). We present an overview on the use of biomonitoring in exposure assessment using phthalates, bisphenol A and other environmental phenols, and perfluorinated chemicals as examples. We discuss some factors relevant for interpreting and understanding biomonitoring data, including selection of both biomarkers of exposure and human matrices, and toxicokinetic information. The use of biomonitoring in human risk assessment is not discussed.

CalTOX, a multimedia total exposure model for hazardous-waste sites; Part 1, Executive summary

Energy Technology Data Exchange (ETDEWEB)

McKone, T.E.

1993-06-01

CalTOX has been developed as a spreadsheet model to assist in health-risk assessments that address contaminated soils and the contamination of adjacent air, surface water, sediments, and ground water. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify and reduce uncertainty in multimedia, multiple-pathway exposure models. This report provides an overview of the CalTOX model components, lists the objectives of the model, describes the philosophy under which the model was developed, identifies the chemical classes for which the model can be used, and describes critical sensitivities and uncertainties. The multimedia transport and transformation model is a dynamic model that can be used to assess time-varying concentrations of contaminants introduced initially to soil layers or for contaminants released continuously to air or water. This model assists the user in examining how chemical and landscape properties impact both the ultimate route and quantity of human contact. Multimedia, multiple pathway exposure models are used in the CalTOX model to estimate average daily potential doses within a human population in the vicinity of a hazardous substances release site. The exposure models encompass twenty-three exposure pathways. The exposure assessment process consists of relating contaminant concentrations in the multimedia model compartments to contaminant concentrations in the media with which a human population has contact (personal air, tap water, foods, household dusts soils, etc.). The average daily dose is the product of the exposure concentrations in these contact media and an intake or uptake factor that relates the concentrations to the distributions of potential dose within the population.

Radiation exposure and risk assessment for critical female body organs

International Nuclear Information System (INIS)

Atwell, W.; Weyland, M.D.; Hardy, A.C.

1991-07-01

Space radiation exposure limits for astronauts are based on recommendations of the National Council on Radiation Protection and Measurements. These limits now include the age at exposure and sex of the astronaut. A recently-developed computerized anatomical female (CAF) model is discussed in detail. Computer-generated, cross-sectional data are presented to illustrate the completeness of the CAF model. By applying ray-tracing techniques, shield distribution functions have been computed to calculate absorbed dose and dose equivalent values for a variety of critical body organs (e.g., breasts, lungs, thyroid gland, etc.) and mission scenarios. Specific risk assessments, i.e., cancer induction and mortality, are reviewed. 13 refs

Quantitative assessment of human and pet exposure to Salmonella associated with dry pet foods.

Science.gov (United States)

Lambertini, Elisabetta; Buchanan, Robert L; Narrod, Clare; Ford, Randall M; Baker, Robert C; Pradhan, Abani K

2016-01-04

Recent Salmonella outbreaks associated with dry pet foods and treats highlight the importance of these foods as previously overlooked exposure vehicles for both pets and humans. In the last decade efforts have been made to raise the safety of this class of products, for instance by upgrading production equipment, cleaning protocols, and finished product testing. However, no comprehensive or quantitative risk profile is available for pet foods, thus limiting the ability to establish safety standards and assess the effectiveness of current and proposed Salmonella control measures. This study sought to develop an ingredients-to-consumer quantitative microbial exposure assessment model to: 1) estimate pet and human exposure to Salmonella via dry pet food, and 2) assess the impact of industry and household-level mitigation strategies on exposure. Data on prevalence and concentration of Salmonella in pet food ingredients, production process parameters, bacterial ecology, and contact transfer in the household were obtained through literature review, industry data, and targeted research. A probabilistic Monte Carlo modeling framework was developed to simulate the production process and basic household exposure routes. Under the range of assumptions adopted in this model, human exposure due to handling pet food is null to minimal if contamination occurs exclusively before extrusion. Exposure increases considerably if recontamination occurs post-extrusion during coating with fat, although mean ingested doses remain modest even at high fat contamination levels, due to the low percent of fat in the finished product. Exposure is highly variable, with the distribution of doses ingested by adult pet owners spanning 3Log CFU per exposure event. Child exposure due to ingestion of 1g of pet food leads to significantly higher doses than adult doses associated with handling the food. Recontamination after extrusion and coating, e.g., via dust or equipment surfaces, may also lead to

The landscape of existing models for high-throughput exposure assessment

DEFF Research Database (Denmark)

Jolliet, O.; Fantke, Peter; Huang, L.

2017-01-01

and ability to easily handle large datasets. For building materials a series of diffusion-based models have been developed to predict the chemicals emissions from building materials to indoor air, but existing models require complex analytical or numerical solutions, which are not suitable for LCA or HTS...... applications. Thus, existing model solutions needed to be simplified for application in LCA and HTS, and a parsimonious model has been developed by Huang et al. (2017) to address this need. For SVOCs, simplified solutions do exist, assuming constant SVOC concentrations in building materials and steadystate...... for skin permeation and volatilization as competing processes and that requires a limited number of readily available physiochemical properties would be suitable for LCA and HTS purposes. Thus, the multi-pathway exposure model for chemicals in cosmetics developed by Ernstoff et al.constitutes a suitable...

Modelling exposure of mammalian predators to anticoagulant rodenticide

Directory of Open Access Journals (Sweden)

Christopher John Topping

2016-12-01

Full Text Available Anticoagulant rodenticides (AR are a widespread and effective method of rodent control but there is concern about the impact these may have on non-target organisms, in particular secondary poisoning of rodent predators. Incidence and concentration of AR in free-living predators in Denmark is very high. We postulate that this is caused by widespread exposure due to widespread use of AR in Denmark in and around buildings. To investigate this theory a spatio-temporal model of AR use and mammalian predator distribution was created. This model was supported by data from an experimental study of mice as vectors of AR, and was used to evaluate likely impacts of restrictions imposed on AR use in Denmark banning the use of rodenticides for plant protection in woodlands and tree-crops. The model uses input based on frequencies and timings of baiting for rodent control for urban, rural and woodland locations and creates an exposure map based on spatio-temporal modelling of movement of mice-vectored AR (based on Apodemus flavicollis. Simulated predator territories are super-imposed over this exposure map to create an exposure index. Predictions from the model concur with field studies of AR prevalence both before and after the change in AR use. In most cases incidence of exposure to AR is predicted to be greater than 90%, although cessation of use in woodlots and Christmas tree plantations should reduce mean exposure concentrations. Model results suggest that the driver of high AR incidence in non-target small mammal predators is likely to be the pattern of use and not the distance AR is vectored. Reducing baiting frequency by 75% had different effects depending on the landscape simulated, but having a maximum of 12% reduction in exposure incidence, and in one landscape a maximum reduction of <2%. We discuss sources of uncertainty in the model and directions for future development of predictive models for environmental impact assessment of rodenticides. The

Retrospective Occupational Exposure Assessment in Community-Based Studies Made Easier

International Nuclear Information System (INIS)

Fritschi, L.; Girschik, J.; Friesen, M.C.; Glass, D.; Monash, G.B.; Sadkowsky, T.

2010-01-01

Occ DEAS Assessing occupational exposure in retrospective community-based case-control studies is difficult as measured exposure data are very seldom available. The expert assessment method is considered the most accurate way to attribute exposure but it is a time consuming and expensive process and may be seen as subjective, non reproducible, and non transparent. In this paper, we describe these problems and outline our solutions as ope rationalized in a web-based software application (Occ DEAS). The novel aspects of Occ DEAS are combining all steps in the assessment into one software package; enmeshing the process of assessment into the development of questionnaires; selecting the exposure(s) of interest; specifying rules for exposure assignment; allowing manual or automatic assessments; ensuring that circumstances in which exposure is possible for an individual are highlighted for review; providing reports to ensure consistency of assessment. Development of this application has the potential to make high-quality occupational assessment more efficient and accessible for epidemiological studies

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

Wishful Thinking? Inside the Black Box of Exposure Assessment.

Science.gov (United States)

Money, Annemarie; Robinson, Christine; Agius, Raymond; de Vocht, Frank

2016-05-01

Decision-making processes used by experts when undertaking occupational exposure assessment are relatively unknown, but it is often assumed that there is a common underlying method that experts employ. However, differences in training and experience of assessors make it unlikely that one general method for expert assessment would exist. Therefore, there are concerns about formalizing, validating, and comparing expert estimates within and between studies that are difficult, if not impossible, to characterize. Heuristics on the other hand (the processes involved in decision making) have been extensively studied. Heuristics are deployed by everyone as short-cuts to make the often complex process of decision-making simpler, quicker, and less burdensome. Experts' assessments are often subject to various simplifying heuristics as a way to reach a decision in the absence of sufficient data. Therefore, investigating the underlying heuristics or decision-making processes involved may help to shed light on the 'black box' of exposure assessment. A mixed method study was conducted utilizing both a web-based exposure assessment exercise incorporating quantitative and semiqualitative elements of data collection, and qualitative semi-structured interviews with exposure assessors. Qualitative data were analyzed using thematic analysis. Twenty-five experts completed the web-based exposure assessment exercise and 8 of these 25 were randomly selected to participate in the follow-up interview. Familiar key themes relating to the exposure assessment exercise emerged; 'intensity'; 'probability'; 'agent'; 'process'; and 'duration' of exposure. However, an important aspect of the detailed follow-up interviews revealed a lack of structure and order with which participants described their decision making. Participants mostly described some form of an iterative process, heavily relying on the anchoring and adjustment heuristic, which differed between experts. In spite of having undertaken

Probabilistic integrated risk assessment of human exposure risk to environmental bisphenol A pollution sources.

Science.gov (United States)

Fu, Keng-Yen; Cheng, Yi-Hsien; Chio, Chia-Pin; Liao, Chung-Min

2016-10-01

Environmental bisphenol A (BPA) exposure has been linked to a variety of adverse health effects such as developmental and reproductive issues. However, establishing a clear association between BPA and the likelihood of human health is complex yet fundamentally uncertain. The purpose of this study was to assess the potential exposure risks from environmental BPA among Chinese population based on five human health outcomes, namely immune response, uterotrophic assay, cardiovascular disease (CVD), diabetes, and behavior change. We addressed these health concerns by using a stochastic integrated risk assessment approach. The BPA dose-dependent likelihood of effects was reconstructed by a series of Hill models based on animal models or epidemiological data. We developed a physiologically based pharmacokinetic (PBPK) model that allows estimation of urinary BPA concentration from external exposures. Here we showed that the daily average exposure concentrations of BPA and urinary BPA estimates were consistent with the published data. We found that BPA exposures were less likely to pose significant risks for infants (0-1 year) and adults (male and female >20 years) with human long-term BPA susceptibility in relation to multiple exposure pathways, and for informing the public of the negligible magnitude of environmental BPA pollution impacts on human health.

An assessment of air pollutant exposure methods in Mexico City, Mexico.

Science.gov (United States)

Rivera-González, Luis O; Zhang, Zhenzhen; Sánchez, Brisa N; Zhang, Kai; Brown, Daniel G; Rojas-Bracho, Leonora; Osornio-Vargas, Alvaro; Vadillo-Ortega, Felipe; O'Neill, Marie S

2015-05-01

Geostatistical interpolation methods to estimate individual exposure to outdoor air pollutants can be used in pregnancy cohorts where personal exposure data are not collected. Our objectives were to a) develop four assessment methods (citywide average (CWA); nearest monitor (NM); inverse distance weighting (IDW); and ordinary Kriging (OK)), and b) compare daily metrics and cross-validations of interpolation models. We obtained 2008 hourly data from Mexico City's outdoor air monitoring network for PM10, PM2.5, O3, CO, NO2, and SO2 and constructed daily exposure metrics for 1,000 simulated individual locations across five populated geographic zones. Descriptive statistics from all methods were calculated for dry and wet seasons, and by zone. We also evaluated IDW and OK methods' ability to predict measured concentrations at monitors using cross validation and a coefficient of variation (COV). All methods were performed using SAS 9.3, except ordinary Kriging which was modeled using R's gstat package. Overall, mean concentrations and standard deviations were similar among the different methods for each pollutant. Correlations between methods were generally high (r=0.77 to 0.99). However, ranges of estimated concentrations determined by NM, IDW, and OK were wider than the ranges for CWA. Root mean square errors for OK were consistently equal to or lower than for the IDW method. OK standard errors varied considerably between pollutants and the computed COVs ranged from 0.46 (least error) for SO2 and PM10 to 3.91 (most error) for PM2.5. OK predicted concentrations measured at the monitors better than IDW and NM. Given the similarity in results for the exposure methods, OK is preferred because this method alone provides predicted standard errors which can be incorporated in statistical models. The daily estimated exposures calculated using these different exposure methods provide flexibility to evaluate multiple windows of exposure during pregnancy, not just trimester or

Modeling human exposure to hazardous-waste sites: a question of completeness

International Nuclear Information System (INIS)

Daniels, J.I.; McKone, T.E.

1991-01-01

In risk analysis, we use human-exposure assessments to translate contaminant sources into quantitative estimates of the amount of contaminant that comes in contact with human-environment boundaries, that is, the lungs, the gastrointestinal tract, and the skin surface of individuals within a specified population. An assessment of intake requires that we determine how much crosses these boundaries. Exposure assessments often rely implicitly in the assumption that exposure can be linked by simple parameters to ambient concentration in air, water, and soil. However, more realistic exposure models require that we abandon such simple assumptions. To link contaminant concentrations in water, air, or soil with potential human intakes, we constrict pathway-exposure factors (PEFs). For each PEF we combine information in environmental partitioning as well as human anatomy, physiology, and patterns into an algebraic term that converts concentrations of contaminants (in mg/L water, mg/m 3 air, and mg/kg soil) into a daily intake per unit body weight in mg/kg-d for a specific rout of exposure such as inhalation, ingestion, or dermal uptake. Using examples involving human exposure to either a radionuclide (tritium, 3 H) or a toxic organic chemical (tetrachloroethylene, PCE) in soil, water, and air, we illustrate the use of PEFs and consider the implications for risk assessment. (au)

Exposure Assessment Tools by Lifestages and Populations - General Population

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

Predictions of models for environmental radiological assessment

International Nuclear Information System (INIS)

Peres, Sueli da Silva; Lauria, Dejanira da Costa; Mahler, Claudio Fernando

2011-01-01

In the field of environmental impact assessment, models are used for estimating source term, environmental dispersion and transfer of radionuclides, exposure pathway, radiation dose and the risk for human beings Although it is recognized that the specific information of local data are important to improve the quality of the dose assessment results, in fact obtaining it can be very difficult and expensive. Sources of uncertainties are numerous, among which we can cite: the subjectivity of modelers, exposure scenarios and pathways, used codes and general parameters. The various models available utilize different mathematical approaches with different complexities that can result in different predictions. Thus, for the same inputs different models can produce very different outputs. This paper presents briefly the main advances in the field of environmental radiological assessment that aim to improve the reliability of the models used in the assessment of environmental radiological impact. The intercomparison exercise of model supplied incompatible results for 137 Cs and 60 Co, enhancing the need for developing reference methodologies for environmental radiological assessment that allow to confront dose estimations in a common comparison base. The results of the intercomparison exercise are present briefly. (author)

Multi-scale spatial modeling of human exposure from local sources to global intake

DEFF Research Database (Denmark)

Wannaz, Cedric; Fantke, Peter; Jolliet, Olivier

2018-01-01

Exposure studies, used in human health risk and impact assessments of chemicals are largely performed locally or regionally. It is usually not known how global impacts resulting from exposure to point source emissions compare to local impacts. To address this problem, we introduce Pangea......, an innovative multi-scale, spatial multimedia fate and exposure assessment model. We study local to global population exposure associated with emissions from 126 point sources matching locations of waste-to-energy plants across France. Results for three chemicals with distinct physicochemical properties...... occur within a 100 km radius from the source. This suggests that, by neglecting distant low-level exposure, local assessments might only account for fractions of global cumulative intakes. We also study ~10,000 emission locations covering France more densely to determine per chemical and exposure route...

Integrated fate modeling for exposure assessment of produced water on the Sable Island Bank (Scotian shelf, Canada).

Science.gov (United States)

Berry, Jody A; Wells, Peter G

2004-10-01

Produced water is the largest waste discharge from the production phase of oil and gas wells. Produced water is a mixture of reservoir formation water and production chemicals from the separation process. This creates a chemical mixture that has several components of toxic concern, ranging from heavy metals to soluble hydrocarbons. Analysis of potential environmental effects from produced water in the Sable Island Bank region (NS, Canada) was conducted using an integrated modeling approach according to the ecological risk assessment framework. A hydrodynamic dispersion model was used to describe the wastewater plume. A second fugacity-based model was used to describe the likely plume partitioning in the local environmental media of water, suspended sediment, biota, and sediment. Results from the integrated modeling showed that the soluble benzene and naphthalene components reach chronic no-effect concentration levels at a distance of 1.0 m from the discharge point. The partition modeling indicated that low persistence was expected because of advection forces caused by tidal currents for the Sable Island Bank system. The exposure assessment for the two soluble hydrocarbon components suggests that the risks of adverse environmental effects from produced water on Sable Island Bank are low.

Safety assessments for potential exposures

International Nuclear Information System (INIS)

Dunn, D.I.

2012-04-01

Safety Assessment of potential exposures have been carried out in major practices, namely: industrial radiography, gamma irradiators and electron accelerators used in industry and research, and radiotherapy. This paper focuses on reviewing safety assessment methodologies and using developed software to analyse radiological accidents, also review, and discuss these past accidents.The primary objective of the assessment is to assess the adequacy of planned or existing measures for protection and safety and to identify any additional measures that should be put in place. As such, both routine use of the source and the probability and magnitude of potential exposures arising from accidents or incidents should be considered. Where the assessment indicates that there is a realistic possibility of an accident affecting workers or members of the public or having consequences for the environment, the registrant or licensee should prepare a suitable emergency plan. A safety assessment for normal operation addresses all the conditions under which the radiation source operates as expected, including all phases of the lifetime of the source. Due account needs to be taken of the different factors and conditions that will apply during non-operational phases, such as installation, commissioning and maintenance. (author)

Pesticide Flow Analysis to Assess Human Exposure in Greenhouse Flower Production in Colombia

Directory of Open Access Journals (Sweden)

Claudia R. Binder

2013-03-01

Full Text Available Human exposure assessment tools represent a means for understanding human exposure to pesticides in agricultural activities and managing possible health risks. This paper presents a pesticide flow analysis modeling approach developed to assess human exposure to pesticide use in greenhouse flower crops in Colombia, focusing on dermal and inhalation exposure. This approach is based on the material flow analysis methodology. The transfer coefficients were obtained using the whole body dosimetry method for dermal exposure and the button personal inhalable aerosol sampler for inhalation exposure, using the tracer uranine as a pesticide surrogate. The case study was a greenhouse rose farm in the Bogota Plateau in Colombia. The approach was applied to estimate the exposure to pesticides such as mancozeb, carbendazim, propamocarb hydrochloride, fosetyl, carboxin, thiram, dimethomorph and mandipropamide. We found dermal absorption estimations close to the AOEL reference values for the pesticides carbendazim, mancozeb, thiram and mandipropamide during the study period. In addition, high values of dermal exposure were found on the forearms, hands, chest and legs of study participants, indicating weaknesses in the overlapping areas of the personal protective equipment parts. These results show how the material flow analysis methodology can be applied in the field of human exposure for early recognition of the dispersion of pesticides and support the development of measures to improve operational safety during pesticide management. Furthermore, the model makes it possible to identify the status quo of the health risk faced by workers in the study area.

A model to systematically employ professional judgment in the Bayesian Decision Analysis for a semiconductor industry exposure assessment.

Science.gov (United States)

Torres, Craig; Jones, Rachael; Boelter, Fred; Poole, James; Dell, Linda; Harper, Paul

2014-01-01

Bayesian Decision Analysis (BDA) uses Bayesian statistics to integrate multiple types of exposure information and classify exposures within the exposure rating categorization scheme promoted in American Industrial Hygiene Association (AIHA) publications. Prior distributions for BDA may be developed from existing monitoring data, mathematical models, or professional judgment. Professional judgments may misclassify exposures. We suggest that a structured qualitative risk assessment (QLRA) method can provide consistency and transparency in professional judgments. In this analysis, we use a structured QLRA method to define prior distributions (priors) for BDA. We applied this approach at three semiconductor facilities in South Korea, and present an evaluation of the performance of structured QLRA for determination of priors, and an evaluation of occupational exposures using BDA. Specifically, the structured QLRA was applied to chemical agents in similar exposure groups to identify provisional risk ratings. Standard priors were developed for each risk rating before review of historical monitoring data. Newly collected monitoring data were used to update priors informed by QLRA or historical monitoring data, and determine the posterior distribution. Exposure ratings were defined by the rating category with the highest probability--i.e., the most likely. We found the most likely exposure rating in the QLRA-informed priors to be consistent with historical and newly collected monitoring data, and the posterior exposure ratings developed with QLRA-informed priors to be equal to or greater than those developed with data-informed priors in 94% of comparisons. Overall, exposures at these facilities are consistent with well-controlled work environments. That is, the 95th percentile of exposure distributions are ≤50% of the occupational exposure limit (OEL) for all chemical-SEG combinations evaluated; and are ≤10% of the limit for 94% of chemical-SEG combinations evaluated.

Quantitative assessment of exposure and risk for three carcinogenics in long-standing pollution sites

International Nuclear Information System (INIS)

Wichmann, H.E.; Wuppertal Univ.; Ihme, W.; Mekel, O.C.L.; Wuppertal Univ.

1993-01-01

The project attempts a quantitative assessment of risks for three carcinogenics that are common in sites of long-standing pollution. Benzo(a)pyrene stands for the group of polycyclic aromatic hydrocarbons, cadmium for heavy metals, and benzene for volatile aromatic compounds. The report discusses the general fundamentals of exposure and risk assessment. The exposure model is described in detail and applied to the three test substances. (orig./MG) [de

Estimating Margin of Exposure to Thyroid Peroxidase Inhibitors Using High-Throughput in vitro Data, High-Throughput Exposure Modeling, and Physiologically Based Pharmacokinetic/Pharmacodynamic Modeling

Science.gov (United States)

Leonard, Jeremy A.; Tan, Yu-Mei; Gilbert, Mary; Isaacs, Kristin; El-Masri, Hisham

2016-01-01

Some pharmaceuticals and environmental chemicals bind the thyroid peroxidase (TPO) enzyme and disrupt thyroid hormone production. The potential for TPO inhibition is a function of both the binding affinity and concentration of the chemical within the thyroid gland. The former can be determined through in vitro assays, and the latter is influenced by pharmacokinetic properties, along with environmental exposure levels. In this study, a physiologically based pharmacokinetic (PBPK) model was integrated with a pharmacodynamic (PD) model to establish internal doses capable of inhibiting TPO in relation to external exposure levels predicted through exposure modeling. The PBPK/PD model was evaluated using published serum or thyroid gland chemical concentrations or circulating thyroxine (T4) and triiodothyronine (T3) hormone levels measured in rats and humans. After evaluation, the model was used to estimate human equivalent intake doses resulting in reduction of T4 and T3 levels by 10% (ED10) for 6 chemicals of varying TPO-inhibiting potencies. These chemicals were methimazole, 6-propylthiouracil, resorcinol, benzophenone-2, 2-mercaptobenzothiazole, and triclosan. Margin of exposure values were estimated for these chemicals using the ED10 and predicted population exposure levels for females of child-bearing age. The modeling approach presented here revealed that examining hazard or exposure alone when prioritizing chemicals for risk assessment may be insufficient, and that consideration of pharmacokinetic properties is warranted. This approach also provides a mechanism for integrating in vitro data, pharmacokinetic properties, and exposure levels predicted through high-throughput means when interpreting adverse outcome pathways based on biological responses. PMID:26865668

Combination of a higher-tier flow-through system and population modeling to assess the effects of time-variable exposure of isoproturon on the green algae Desmodesmus subspicatus and Pseudokirchneriella subcapitata.

Science.gov (United States)

Weber, Denis; Schaefer, Dieter; Dorgerloh, Michael; Bruns, Eric; Goerlitz, Gerhard; Hammel, Klaus; Preuss, Thomas G; Ratte, Hans Toni

2012-04-01

A flow-through system was developed to investigate the effects of time-variable exposure of pesticides on algae. A recently developed algae population model was used for simulations supported and verified by laboratory experiments. Flow-through studies with Desmodesmus subspicatus and Pseudokirchneriella subcapitata under time-variable exposure to isoproturon were performed, in which the exposure patterns were based on the results of FOrum for Co-ordination of pesticide fate models and their USe (FOCUS) model calculations for typical exposure situations via runoff or drain flow. Different types of pulsed exposure events were realized, including a whole range of repeated pulsed and steep peaks as well as periods of constant exposure. Both species recovered quickly in terms of growth from short-term exposure and according to substance dissipation from the system. Even at a peak 10 times the maximum predicted environmental concentration of isoproturon, only transient effects occurred on algae populations. No modified sensitivity or reduced growth was observed after repeated exposure. Model predictions of algal growth in the flow-through tests agreed well with the experimental data. The experimental boundary conditions and the physiological properties of the algae were used as the only model input. No calibration or parameter fitting was necessary. The combination of the flow-through experiments with the algae population model was revealed to be a powerful tool for the assessment of pulsed exposure on algae. It allowed investigating the growth reduction and recovery potential of algae after complex exposure, which is not possible with standard laboratory experiments alone. The results of the combined approach confirm the beneficial use of population models as supporting tools in higher-tier risk assessments of pesticides. Copyright © 2012 SETAC.

Development of model for assessment of radiation discharge to the environment

International Nuclear Information System (INIS)

Shang Zhaorong; Wu Hao; Liu Hua

2003-01-01

International Atomic Energy Agency (IAEA) establish basic and detailed requirements for protection against the risks associated with exposure to radiation and for the safety of radiation sources that may deliver such exposure, in which, particularly emphasize to 'make an assessment of the nature, magnitude and likelihood of the exposure attributed to the source'. It is clear that the assessment of the consequential radiation exposure arising from any releases of radioactive materials to the environment will have to rely on some form of model. This paper summary recent progress in radiation protection policy and radioecology research and primary concludes the basis requirements in assessment model development

Multi-pathway exposure modelling of chemicals in cosmetics with application to shampoo

Science.gov (United States)

We present a novel multi-pathway, mass balance based, fate and exposure model compatible with life cycle and high-throughput screening assessments of chemicals in cosmetic products. The exposures through product use as well as post-use emissions and environmental media were quant...

Determining the validity of exposure models for environmental epidemiology : predicting electromagnetic fields from mobile phone base stations

NARCIS (Netherlands)

Beekhuizen, Johan|info:eu-repo/dai/nl/34472641X

2014-01-01

One of the key challenges in environmental epidemiology is the exposure assessment of large populations. Spatial exposure models have been developed that predict exposure to the pollutant of interest for large study sizes. However, the validity of these exposure models is often unknown. In this

Using toxicokinetic-toxicodynamic modeling as an acute risk assessment refinement approach in vertebrate ecological risk assessment.

Science.gov (United States)

Ducrot, Virginie; Ashauer, Roman; Bednarska, Agnieszka J; Hinarejos, Silvia; Thorbek, Pernille; Weyman, Gabriel

2016-01-01

Recent guidance identified toxicokinetic-toxicodynamic (TK-TD) modeling as a relevant approach for risk assessment refinement. Yet, its added value compared to other refinement options is not detailed, and how to conduct the modeling appropriately is not explained. This case study addresses these issues through 2 examples of individual-level risk assessment for 2 hypothetical plant protection products: 1) evaluating the risk for small granivorous birds and small omnivorous mammals of a single application, as a seed treatment in winter cereals, and 2) evaluating the risk for fish after a pulsed treatment in the edge-of-field zone. Using acute test data, we conducted the first tier risk assessment as defined in the European Food Safety Authority (EFSA) guidance. When first tier risk assessment highlighted a concern, refinement options were discussed. Cases where the use of models should be preferred over other existing refinement approaches were highlighted. We then practically conducted the risk assessment refinement by using 2 different models as examples. In example 1, a TK model accounting for toxicokinetics and relevant feeding patterns in the skylark and in the wood mouse was used to predict internal doses of the hypothetical active ingredient in individuals, based on relevant feeding patterns in an in-crop situation, and identify the residue levels leading to mortality. In example 2, a TK-TD model accounting for toxicokinetics, toxicodynamics, and relevant exposure patterns in the fathead minnow was used to predict the time-course of fish survival for relevant FOCUS SW exposure scenarios and identify which scenarios might lead to mortality. Models were calibrated using available standard data and implemented to simulate the time-course of internal dose of active ingredient or survival for different exposure scenarios. Simulation results were discussed and used to derive the risk assessment refinement endpoints used for decision. Finally, we compared the

Assessing Climate Change Impacts on Wildfire Exposure in Mediterranean Areas.

Science.gov (United States)

Lozano, Olga M; Salis, Michele; Ager, Alan A; Arca, Bachisio; Alcasena, Fermin J; Monteiro, Antonio T; Finney, Mark A; Del Giudice, Liliana; Scoccimarro, Enrico; Spano, Donatella

2017-10-01

We used simulation modeling to assess potential climate change impacts on wildfire exposure in Italy and Corsica (France). Weather data were obtained from a regional climate model for the period 1981-2070 using the IPCC A1B emissions scenario. Wildfire simulations were performed with the minimum travel time fire spread algorithm using predicted fuel moisture, wind speed, and wind direction to simulate expected changes in weather for three climatic periods (1981-2010, 2011-2040, and 2041-2070). Overall, the wildfire simulations showed very slight changes in flame length, while other outputs such as burn probability and fire size increased significantly in the second future period (2041-2070), especially in the southern portion of the study area. The projected changes fuel moisture could result in a lengthening of the fire season for the entire study area. This work represents the first application in Europe of a methodology based on high resolution (250 m) landscape wildfire modeling to assess potential impacts of climate changes on wildfire exposure at a national scale. The findings can provide information and support in wildfire management planning and fire risk mitigation activities. © 2016 Society for Risk Analysis.

Progress in human exposure assessment for biocidal products

NARCIS (Netherlands)

Hemmen, J.J. van

2004-01-01

An important shortcoming in our present knowledge required for risk assessment of biocidal products is the assessment of human exposure. This knowledge gap has been filled in a preliminary fashion with the TNsG on human exposure to biocidal products (available from the ECB website). Explicit User

Assessment of chemical exposures: calculation methods for environmental professionals

National Research Council Canada - National Science Library

Daugherty, Jack E

1997-01-01

... on by scientists, businessmen, and policymakers. Assessment of Chemical Exposures: Calculation Methods for Environmental Professionals addresses the expanding scope of exposure assessments in both the workplace and environment...

Default values for assessment of potential dermal exposure of the hands to industrial chemicals in the scope of regulatory risk assessments

NARCIS (Netherlands)

Marquart, H.; Warren, N.D.; Laitinen, J.; Hemmen, J.J. van

2006-01-01

Dermal exposure needs to be addressed in regulatory risk assessment of chemicals. The models used so far are based on very limited data. The EU project RISKOFDERM has gathered a large number of new measurements on dermal exposure to industrial chemicals in various work situations, together with

Comparison of modeled estimates of inhalation exposure to aerosols during use of consumer spray products.

Science.gov (United States)

Park, Jihoon; Yoon, Chungsik; Lee, Kiyoung

2018-05-30

In the field of exposure science, various exposure assessment models have been developed to complement experimental measurements; however, few studies have been published on their validity. This study compares the estimated inhaled aerosol doses of several inhalation exposure models to experimental measurements of aerosols released from consumer spray products, and then compares deposited doses within different parts of the human respiratory tract according to deposition models. Exposure models, including the European Center for Ecotoxicology of Chemicals Targeted Risk Assessment (ECETOC TRA), the Consumer Exposure Model (CEM), SprayExpo, ConsExpo Web and ConsExpo Nano, were used to estimate the inhaled dose under various exposure scenarios, and modeled and experimental estimates were compared. The deposited dose in different respiratory regions was estimated using the International Commission on Radiological Protection model and multiple-path particle dosimetry models under the assumption of polydispersed particles. The modeled estimates of the inhaled doses were accurate in the short term, i.e., within 10 min of the initial spraying, with a differences from experimental estimates ranging from 0 to 73% among the models. However, the estimates for long-term exposure, i.e., exposure times of several hours, deviated significantly from the experimental estimates in the absence of ventilation. The differences between the experimental and modeled estimates of particle number and surface area were constant over time under ventilated conditions. ConsExpo Nano, as a nano-scale model, showed stable estimates of short-term exposure, with a difference from the experimental estimates of less than 60% for all metrics. The deposited particle estimates were similar among the deposition models, particularly in the nanoparticle range for the head airway and alveolar regions. In conclusion, the results showed that the inhalation exposure models tested in this study are suitable

The multimedia models for the evaluation of exposure bond to the atmospheric emissions of classified installations

International Nuclear Information System (INIS)

Bonnard, R.

2001-12-01

Risk assessment and environmental impacts studies are realized to preserve the public health. Today one of the most used approach is the use of an atmospheric dispersion model to assess the risks. The data are then injected in a calculation software of exposure bond to polluted soils, to evaluate the risks of non direct exposure. This report details and evaluates the models corresponding to the need: the methodology for assessing Health Risks associated with multiple pathways of exposure to combustor, human health risk assessment proto col for hazardous waste combustion facilities, EUSES, CALTOX, MEPAS, MEND-TOX, RESRAD, MMSOILS, FRAMES-HWIR, PC-GEMS and TRIM. (A.L.B.)

Korean Ministry of Environment's web-based visual consumer product exposure and risk assessment system (COPER).

Science.gov (United States)

Lee, Hunjoo; Lee, Kiyoung; Park, Ji Young; Min, Sung-Gi

2017-05-01

With support from the Korean Ministry of the Environment (ME), our interdisciplinary research staff developed the COnsumer Product Exposure and Risk assessment system (COPER). This system includes various databases and features that enable the calculation of exposure and determination of risk caused by consumer products use. COPER is divided into three tiers: the integrated database layer (IDL), the domain specific service layer (DSSL), and the exposure and risk assessment layer (ERAL). IDL is organized by the form of the raw data (mostly non-aggregated data) and includes four sub-databases: a toxicity profile, an inventory of Korean consumer products, the weight fractions of chemical substances in the consumer products determined by chemical analysis and national representative exposure factors. DSSL provides web-based information services corresponding to each database within IDL. Finally, ERAL enables risk assessors to perform various exposure and risk assessments, including exposure scenario design via either inhalation or dermal contact by using or organizing each database in an intuitive manner. This paper outlines the overall architecture of the system and highlights some of the unique features of COPER based on visual and dynamic rendering engine for exposure assessment model on web.

Multi-pathway exposure modelling of chemicals in cosmetics with application to shampoo

DEFF Research Database (Denmark)

Ernstoff, Alexi S.; Fantke, Peter; Csiszar, Susan A.

2016-01-01

We present a novel multi-pathway, mass balance based, fate and exposure model compatible with life cycle and high-throughput screening assessments of chemicals in cosmetic products. The exposures through product use as well as post-use emissions and environmental media were quantified based...

The EPA's human exposure research program for assessing cumulative risk in communities.

Science.gov (United States)

Zartarian, Valerie G; Schultz, Bradley D

2010-06-01

Communities are faced with challenges in identifying and prioritizing environmental issues, taking actions to reduce their exposures, and determining their effectiveness for reducing human health risks. Additional challenges include determining what scientific tools are available and most relevant, and understanding how to use those tools; given these barriers, community groups tend to rely more on risk perception than science. The U.S. Environmental Protection Agency's Office of Research and Development, National Exposure Research Laboratory (NERL) and collaborators are developing and applying tools (models, data, methods) for enhancing cumulative risk assessments. The NERL's "Cumulative Communities Research Program" focuses on key science questions: (1) How to systematically identify and prioritize key chemical stressors within a given community?; (2) How to develop estimates of exposure to multiple stressors for individuals in epidemiologic studies?; and (3) What tools can be used to assess community-level distributions of exposures for the development and evaluation of the effectiveness of risk reduction strategies? This paper provides community partners and scientific researchers with an understanding of the NERL research program and other efforts to address cumulative community risks; and key research needs and opportunities. Some initial findings include the following: (1) Many useful tools exist for components of risk assessment, but need to be developed collaboratively with end users and made more comprehensive and user-friendly for practical application; (2) Tools for quantifying cumulative risks and impact of community risk reduction activities are also needed; (3) More data are needed to assess community- and individual-level exposures, and to link exposure-related information with health effects; and (4) Additional research is needed to incorporate risk-modifying factors ("non-chemical stressors") into cumulative risk assessments. The products of this

Use of an aggregate exposure model to estimate consumer exposure to fragrance ingredients in personal care and cosmetic products.

Science.gov (United States)

Safford, B; Api, A M; Barratt, C; Comiskey, D; Daly, E J; Ellis, G; McNamara, C; O'Mahony, C; Robison, S; Smith, B; Thomas, R; Tozer, S

2015-08-01

Ensuring the toxicological safety of fragrance ingredients used in personal care and cosmetic products is essential in product development and design, as well as in the regulatory compliance of the products. This requires an accurate estimation of consumer exposure which, in turn, requires an understanding of consumer habits and use of products. Where ingredients are used in multiple product types, it is important to take account of aggregate exposure in consumers using these products. This publication investigates the use of a newly developed probabilistic model, the Creme RIFM model, to estimate aggregate exposure to fragrance ingredients using the example of 2-phenylethanol (PEA). The output shown demonstrates the utility of the model in determining systemic and dermal exposure to fragrances from individual products, and aggregate exposure. The model provides valuable information not only for risk assessment, but also for risk management. It should be noted that data on the concentrations of PEA in products used in this article were obtained from limited sources and not the standard, industry wide surveys typically employed by the fragrance industry and are thus presented here to illustrate the output and utility of the newly developed model. They should not be considered an accurate representation of actual exposure to PEA. Copyright © 2015 Elsevier Inc. All rights reserved.

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

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)

Underwater noise modelling for environmental impact assessment

Energy Technology Data Exchange (ETDEWEB)

Farcas, Adrian [Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR33 0HT (United Kingdom); Thompson, Paul M. [Lighthouse Field Station, Institute of Biological and Environmental Sciences, University of Aberdeen, Cromarty IV11 8YL (United Kingdom); Merchant, Nathan D., E-mail: nathan.merchant@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR33 0HT (United Kingdom)

2016-02-15

Assessment of underwater noise is increasingly required by regulators of development projects in marine and freshwater habitats, and noise pollution can be a constraining factor in the consenting process. Noise levels arising from the proposed activity are modelled and the potential impact on species of interest within the affected area is then evaluated. Although there is considerable uncertainty in the relationship between noise levels and impacts on aquatic species, the science underlying noise modelling is well understood. Nevertheless, many environmental impact assessments (EIAs) do not reflect best practice, and stakeholders and decision makers in the EIA process are often unfamiliar with the concepts and terminology that are integral to interpreting noise exposure predictions. In this paper, we review the process of underwater noise modelling and explore the factors affecting predictions of noise exposure. Finally, we illustrate the consequences of errors and uncertainties in noise modelling, and discuss future research needs to reduce uncertainty in noise assessments.

Underwater noise modelling for environmental impact assessment

International Nuclear Information System (INIS)

Farcas, Adrian; Thompson, Paul M.; Merchant, Nathan D.

2016-01-01

Assessment of underwater noise is increasingly required by regulators of development projects in marine and freshwater habitats, and noise pollution can be a constraining factor in the consenting process. Noise levels arising from the proposed activity are modelled and the potential impact on species of interest within the affected area is then evaluated. Although there is considerable uncertainty in the relationship between noise levels and impacts on aquatic species, the science underlying noise modelling is well understood. Nevertheless, many environmental impact assessments (EIAs) do not reflect best practice, and stakeholders and decision makers in the EIA process are often unfamiliar with the concepts and terminology that are integral to interpreting noise exposure predictions. In this paper, we review the process of underwater noise modelling and explore the factors affecting predictions of noise exposure. Finally, we illustrate the consequences of errors and uncertainties in noise modelling, and discuss future research needs to reduce uncertainty in noise assessments.

Matrix Population Model for Estimating Effects from Time-Varying Aquatic Exposures: Technical Documentation

Science.gov (United States)

The Office of Pesticide Programs models daily aquatic pesticide exposure values for 30 years in its risk assessments. However, only a fraction of that information is typically used in these assessments. The population model employed herein is a deterministic, density-dependent pe...

Environmental exposure assessment in European birth cohorts: results from the ENRIECO project

Directory of Open Access Journals (Sweden)

Gehring Ulrike

2013-01-01

Full Text Available Abstract 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 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=33, outdoor air pollution, and allergens and microbial agents (N=27. Exposure modeling is increasingly used for long-term air pollution exposure assessment; biomonitoring is used for assessment of exposure to metals, POPs and other chemicals; and environmental monitoring for house dust mite exposure assessment. Collaborative analyses with data from several birth cohorts have already been performed successfully for outdoor air pollution, water contamination, allergens, biological contaminants, molds, POPs and SHS. Key success factors for collaborative analyses are common definitions of main exposure and health variables. Our review emphasizes that such common definitions need ideally be arrived at in the study design phase. However, careful comparison of methods used in existing studies also offers excellent opportunities for collaborative analyses. Investigators can use this review to evaluate the potential for future collaborative analyses with respect to data availability and methods used in the different cohorts and to identify potential partners

Using cell phone location to assess misclassification errors in air pollution exposure estimation.

Science.gov (United States)

Yu, Haofei; Russell, Armistead; Mulholland, James; Huang, Zhijiong

2018-02-01

Air pollution epidemiologic and health impact studies often rely on home addresses to estimate individual subject's pollution exposure. In this study, we used detailed cell phone location data, the call detail record (CDR), to account for the impact of spatiotemporal subject mobility on estimates of ambient air pollutant exposure. This approach was applied on a sample with 9886 unique simcard IDs in Shenzhen, China, on one mid-week day in October 2013. Hourly ambient concentrations of six chosen pollutants were simulated by the Community Multi-scale Air Quality model fused with observational data, and matched with detailed location data for these IDs. The results were compared with exposure estimates using home addresses to assess potential exposure misclassification errors. We found the misclassifications errors are likely to be substantial when home location alone is applied. The CDR based approach indicates that the home based approach tends to over-estimate exposures for subjects with higher exposure levels and under-estimate exposures for those with lower exposure levels. Our results show that the cell phone location based approach can be used to assess exposure misclassification error and has the potential for improving exposure estimates in air pollution epidemiology studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Hygiene and legal aspects of occupational exposure assessment to cytostatics].

Science.gov (United States)

Kupczewska-Dobecka, Małgorzata; Pałaszewska-Tkacz, Anna; Czerczak, Sławomir; Konieczko, Katarzyna

2018-01-01

The employers responsibilities for the assessment of occupational exposure to cytostatics in the workplace were analyzed in the light of existing legal regulations. Cytostatics may pose a threat to health and life of workers taking care of patients treated oncologically, i.e., pharmacists, physicians, nurses and other personnel. The significant scale of occupational exposure to cytostatics in Poland is confirmed by the data collected in the Central Register of Data on Exposure to Carcinogenic or Mutagenic Substances, Mixtures, Agents or Technological Processes, maintained by the Nofer Institute of Occupational Medicine, Łódź, Poland. The issue of occupational risk assessment of exposure to cytostatics gives raise to numerous concerns. Polish regulations concerning health protection of employees occupationally exposed to cytostatics are not unequivocal, as they are derived from different areas of the law, especially those applying to hazard classification, labeling and preparation of safety data sheets for cytostatics. There are neither binding occupational exposure limits legally set for active compounds of antineoplastic drugs nor methods for monitoring of these substances concentrations in a worker's breathing zone and biological material. This prevents the employer to carry out the correct assessment of occupational exposure, the results of which are the basis for preparing the proper preventive strategy. In this article the consequences of amendments to the European chemical legislation for employers responsible for adequate protection of health and life of employees exposed to cytostatics, were discussed, as well as some legal changes aimed at a better health and life protection of workers exposed to cytostatics in a workplace were proposed. Med Pr 2018;69(1):77-92. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Final report on the Project Research 'Assessment of Human Exposure to Environmental Radiation'

International Nuclear Information System (INIS)

1989-03-01

This is the final report of the Project Research, 'Assessment of Human Exposure to Environmental Radiation', which has been conducted during the period 1983-1988. With the objective of assessing risk of environmental radioactivity to the population, the Project was divided into the following five research groups: (1) research for establishing calculation models and parameters in transfer of radionuclides from crop species through the human body; (2) research for analyzing transfer of radionuclides in the ocean and their contributions to exposure doses in the human body; (3) research for surveying accuracy of exposure models for the external body and respiratory organ and the influential factors; (4) research for determining uptake and biokinetics of radionuclides in the body; and (5) research for estimating and evaluating physical and physiological characteristics of reference Japanese man and the populaltion doses. Effluents from nuclear power plants and reprocessing plants were regarded as radionuclide sources in the water and atmosphere. (N.K.)

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)

Control banding tools for occupational exposure assessment of nanomaterials - Ready for use in a regulatory context?

DEFF Research Database (Denmark)

Liguori, Biase; Hansen, Steffen Foss; Baun, Anders

2016-01-01

area of concern. Therefore, a number of Control Banding (CB)-based tools have been developed in order to assess and manage the potential risks associated with occupational exposure to nanomaterials. In this paper we provide a comparative analysis of different nanomaterial-specific types of control-banding/risk...... developed for different purposes, with different application domains and inclusion criteria. The exposure assessments and derived risk levels are based on different concepts and assumptions and outputs in different formats. The use of requested input parameters for exposure assessment differ greatly among...... the tools. Therefore, direct inter-comparison and combination of the different models into a larger holistic framework is not immediately possible. Harmonization of input parameters and output could allow establishment of an exposure assessment framework with different levels of information requirements....

Estimators for longitudinal latent exposure models: examining measurement model assumptions.

Science.gov (United States)

Sánchez, Brisa N; Kim, Sehee; Sammel, Mary D

2017-06-15

Latent variable (LV) models are increasingly being used in environmental epidemiology as a way to summarize multiple environmental exposures and thus minimize statistical concerns that arise in multiple regression. LV models may be especially useful when multivariate exposures are collected repeatedly over time. LV models can accommodate a variety of assumptions but, at the same time, present the user with many choices for model specification particularly in the case of exposure data collected repeatedly over time. For instance, the user could assume conditional independence of observed exposure biomarkers given the latent exposure and, in the case of longitudinal latent exposure variables, time invariance of the measurement model. Choosing which assumptions to relax is not always straightforward. We were motivated by a study of prenatal lead exposure and mental development, where assumptions of the measurement model for the time-changing longitudinal exposure have appreciable impact on (maximum-likelihood) inferences about the health effects of lead exposure. Although we were not particularly interested in characterizing the change of the LV itself, imposing a longitudinal LV structure on the repeated multivariate exposure measures could result in high efficiency gains for the exposure-disease association. We examine the biases of maximum likelihood estimators when assumptions about the measurement model for the longitudinal latent exposure variable are violated. We adapt existing instrumental variable estimators to the case of longitudinal exposures and propose them as an alternative to estimate the health effects of a time-changing latent predictor. We show that instrumental variable estimators remain unbiased for a wide range of data generating models and have advantages in terms of mean squared error. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Risk of breast cancer following exposure to tetrachloroethylene-contaminated drinking water in Cape Cod, Massachusetts: reanalysis of a case-control study using a modified exposure assessment

Directory of Open Access Journals (Sweden)

Webster Thomas F

2011-05-01

Full Text Available Abstract Background Tetrachloroethylene (PCE is an important occupational chemical used in metal degreasing and drycleaning and a prevalent drinking water contaminant. Exposure often occurs with other chemicals but it occurred alone in a pattern that reduced the likelihood of confounding in a unique scenario on Cape Cod, Massachusetts. We previously found a small to moderate increased risk of breast cancer among women with the highest exposures using a simple exposure model. We have taken advantage of technical improvements in publically available software to incorporate a more sophisticated determination of water flow and direction to see if previous results were robust to more accurate exposure assessment. Methods The current analysis used PCE exposure estimates generated with the addition of water distribution modeling software (EPANET 2.0 to test model assumptions, compare exposure distributions to prior methods, and re-examine the risk of breast cancer. In addition, we applied data smoothing to examine nonlinear relationships between breast cancer and exposure. We also compared a set of measured PCE concentrations in water samples collected in 1980 to modeled estimates. Results Thirty-nine percent of individuals considered unexposed in prior epidemiological analyses were considered exposed using the current method, but mostly at low exposure levels. As a result, the exposure distribution was shifted downward resulting in a lower value for the 90th percentile, the definition of "high exposure" in prior analyses. The current analyses confirmed a modest increase in the risk of breast cancer for women with high PCE exposure levels defined by either the 90th percentile (adjusted ORs 1.0-1.5 for 0-19 year latency assumptions or smoothing analysis cut point (adjusted ORs 1.3-2.0 for 0-15 year latency assumptions. Current exposure estimates had a higher correlation with PCE concentrations in water samples (Spearman correlation coefficient = 0.65, p

Multiple-Strain Approach and Probabilistic Modeling of Consumer Habits in Quantitative Microbial Risk Assessment: A Quantitative Assessment of Exposure to Staphylococcal Enterotoxin A in Raw Milk.

Science.gov (United States)

Crotta, Matteo; Rizzi, Rita; Varisco, Giorgio; Daminelli, Paolo; Cunico, Elena Cosciani; Luini, Mario; Graber, Hans Ulrich; Paterlini, Franco; Guitian, Javier

2016-03-01

Quantitative microbial risk assessment (QMRA) models are extensively applied to inform management of a broad range of food safety risks. Inevitably, QMRA modeling involves an element of simplification of the biological process of interest. Two features that are frequently simplified or disregarded are the pathogenicity of multiple strains of a single pathogen and consumer behavior at the household level. In this study, we developed a QMRA model with a multiple-strain approach and a consumer phase module (CPM) based on uncertainty distributions fitted from field data. We modeled exposure to staphylococcal enterotoxin A in raw milk in Lombardy; a specific enterotoxin production module was thus included. The model is adaptable and could be used to assess the risk related to other pathogens in raw milk as well as other staphylococcal enterotoxins. The multiplestrain approach, implemented as a multinomial process, allowed the inclusion of variability and uncertainty with regard to pathogenicity at the bacterial level. Data from 301 questionnaires submitted to raw milk consumers were used to obtain uncertainty distributions for the CPM. The distributions were modeled to be easily updatable with further data or evidence. The sources of uncertainty due to the multiple-strain approach and the CPM were identified, and their impact on the output was assessed by comparing specific scenarios to the baseline. When the distributions reflecting the uncertainty in consumer behavior were fixed to the 95th percentile, the risk of exposure increased up to 160 times. This reflects the importance of taking into consideration the diversity of consumers' habits at the household level and the impact that the lack of knowledge about variables in the CPM can have on the final QMRA estimates. The multiple-strain approach lends itself to use in other food matrices besides raw milk and allows the model to better capture the complexity of the real world and to be capable of geographical

The Potential Neurotoxic Effects of Low-Dose Sarin Exposure in a Guinea Pig Model

Science.gov (United States)

2002-01-01

1 THE POTENTIAL NEUROTOXIC EFFECTS OF LOW-DOSE SARIN EXPOSURE IN A GUINEA PIG MODEL Melinda R. Roberson, PhD, Michelle B. Schmidt...Proving Ground, MD 21010 USA ABSTRACT This study is assessing the effects in guinea pigs of repeated low-dose exposure to the nerve...COVERED - 4. TITLE AND SUBTITLE The Potential Neurotoxic Effects Of Low-Dose Sarin Exposure In A Guinea Pig Model 5a. CONTRACT NUMBER 5b

Analysis of coupled model uncertainties in source-to-dose modeling of human exposures to ambient air pollution: A PM 2.5 case study

Science.gov (United States)

Özkaynak, Halûk; Frey, H. Christopher; Burke, Janet; Pinder, Robert W.

Quantitative assessment of human exposures and health effects due to air pollution involve detailed characterization of impacts of air quality on exposure and dose. A key challenge is to integrate these three components on a consistent spatial and temporal basis taking into account linkages and feedbacks. The current state-of-practice for such assessments is to exercise emission, meteorology, air quality, exposure, and dose models separately, and to link them together by using the output of one model as input to the subsequent downstream model. Quantification of variability and uncertainty has been an important topic in the exposure assessment community for a number of years. Variability refers to differences in the value of a quantity (e.g., exposure) over time, space, or among individuals. Uncertainty refers to lack of knowledge regarding the true value of a quantity. An emerging challenge is how to quantify variability and uncertainty in integrated assessments over the source-to-dose continuum by considering contributions from individual as well as linked components. For a case study of fine particulate matter (PM 2.5) in North Carolina during July 2002, we characterize variability and uncertainty associated with each of the individual concentration, exposure and dose models that are linked, and use a conceptual framework to quantify and evaluate the implications of coupled model uncertainties. We find that the resulting overall uncertainties due to combined effects of both variability and uncertainty are smaller (usually by a factor of 3-4) than the crudely multiplied model-specific overall uncertainty ratios. Future research will need to examine the impact of potential dependencies among the model components by conducting a truly coupled modeling analysis.

Assessment of long-term spatio-temporal radiofrequency electromagnetic field exposure.

Science.gov (United States)

Aerts, Sam; Wiart, Joe; Martens, Luc; Joseph, Wout

2018-02-01

As both the environment and telecommunications networks are inherently dynamic, our exposure to environmental radiofrequency (RF) electromagnetic fields (EMF) at an arbitrary location is not at all constant in time. In this study, more than a year's worth of measurement data collected in a fixed low-cost exposimeter network distributed over an urban environment was analysed and used to build, for the first time, a full spatio-temporal surrogate model of outdoor exposure to downlink Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) signals. Though no global trend was discovered over the measuring period, the difference in measured exposure between two instances could reach up to 42dB (a factor 12,000 in power density). Furthermore, it was found that, taking into account the hour and day of the measurement, the accuracy of the surrogate model in the area under study was improved by up to 50% compared to models that neglect the daily temporal variability of the RF signals. However, further study is required to assess the extent to which the results obtained in the considered environment can be extrapolated to other geographic locations. Copyright © 2017 Elsevier Inc. All rights reserved.

Historical Exposures to Chemicals at the Rocky Flats Nuclear Weapons Plant: A Pilot Retrospective Exposure Assessment

Energy Technology Data Exchange (ETDEWEB)

Robertson, Janeen Denise [Univ. of New Mexico, Albuquerque, NM (United States)

1999-02-01

In a mortality study of white males who had worked at the Rocky Flats Nuclear Weapons Plant between 1952 and 1979, an increased number of deaths from benign and unspecified intracranial neoplasms was found. A case-control study nested within this cohort investigated the hypothesis that an association existed between brain tumor death and exposure to either internally deposited plutonium or external ionizing radiation. There was no statistically significant association found between estimated radiation exposure from internally deposited plutonium and the development of brain tumors. Exposure by job or work area showed no significant difference between the cohort and the control groups. An update of the study found elevated risk estimates for (1) all lymphopoietic neoplasms, and (2) all causes of death in employees with body burdens greater than or equal to two nanocuries of plutonium. There was an excess of brain tumors for the entire cohort. Similar cohort studies conducted on worker populations from other plutonium handling facilities have not yet shown any elevated risks for brain tumors. Historically, the Rocky Flats Nuclear Weapons Plant used large quantities of chemicals in their production operations. The use of solvents, particularly carbon tetrachloride, was unique to Rocky Flats. No investigation of the possible confounding effects of chemical exposures was done in the initial studies. The objectives of the present study are to (1) investigate the history of chemical use at the Rocky Flats facility; (2) locate and analyze chemical monitoring information in order to assess employee exposure to the chemicals that were used in the highest volume; and (3) determine the feasibility of establishing a chemical exposure assessment model that could be used in future epidemiology studies.

Spatiotemporal air pollution exposure assessment for a Canadian population-based lung cancer case-control study

Directory of Open Access Journals (Sweden)

Hystad Perry

2012-04-01

Full Text Available Abstract Background Few epidemiological studies of air pollution have used residential histories to develop long-term retrospective exposure estimates for multiple ambient air pollutants and vehicle and industrial emissions. We present such an exposure assessment for a Canadian population-based lung cancer case-control study of 8353 individuals using self-reported residential histories from 1975 to 1994. We also examine the implications of disregarding and/or improperly accounting for residential mobility in long-term exposure assessments. Methods National spatial surfaces of ambient air pollution were compiled from recent satellite-based estimates (for PM2.5 and NO2 and a chemical transport model (for O3. The surfaces were adjusted with historical annual air pollution monitoring data, using either spatiotemporal interpolation or linear regression. Model evaluation was conducted using an independent ten percent subset of monitoring data per year. Proximity to major roads, incorporating a temporal weighting factor based on Canadian mobile-source emission estimates, was used to estimate exposure to vehicle emissions. A comprehensive inventory of geocoded industries was used to estimate proximity to major and minor industrial emissions. Results Calibration of the national PM2.5 surface using annual spatiotemporal interpolation predicted historical PM2.5 measurement data best (R2 = 0.51, while linear regression incorporating the national surfaces, a time-trend and population density best predicted historical concentrations of NO2 (R2 = 0.38 and O3 (R2 = 0.56. Applying the models to study participants residential histories between 1975 and 1994 resulted in mean PM2.5, NO2 and O3 exposures of 11.3 μg/m3 (SD = 2.6, 17.7 ppb (4.1, and 26.4 ppb (3.4 respectively. On average, individuals lived within 300 m of a highway for 2.9 years (15% of exposure-years and within 3 km of a major industrial emitter for 6.4 years (32% of exposure-years. Approximately 50

ASSESSING HUMAN EXPOSURE TO GRASS POLLEN IN DENMARK

DEFF Research Database (Denmark)

Peel, Robert George; Hertel, Ole; Herbert, Rob

Objectives: Exposure to pollen is typically assessed using data collected at fixed roof-top monitoring stations, which give a general picture of airborne pollen concentrations over a wide region. Actual exposure levels can be obtained through personal exposure monitoring. This is typically done u...

[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.

Modeling approaches for characterizing and evaluating environmental exposure to engineered nanomaterials in support of risk-based decision making.

Science.gov (United States)

Hendren, Christine Ogilvie; Lowry, Michael; Grieger, Khara D; Money, Eric S; Johnston, John M; Wiesner, Mark R; Beaulieu, Stephen M

2013-02-05

As the use of engineered nanomaterials becomes more prevalent, the likelihood of unintended exposure to these materials also increases. Given the current scarcity of experimental data regarding fate, transport, and bioavailability, determining potential environmental exposure to these materials requires an in depth analysis of modeling techniques that can be used in both the near- and long-term. Here, we provide a critical review of traditional and emerging exposure modeling approaches to highlight the challenges that scientists and decision-makers face when developing environmental exposure and risk assessments for nanomaterials. We find that accounting for nanospecific properties, overcoming data gaps, realizing model limitations, and handling uncertainty are key to developing informative and reliable environmental exposure and risk assessments for engineered nanomaterials. We find methods suited to recognizing and addressing significant uncertainty to be most appropriate for near-term environmental exposure modeling, given the current state of information and the current insufficiency of established deterministic models to address environmental exposure to engineered nanomaterials.

A spatiotemporal multi-hazard exposure assessment based on property data

Science.gov (United States)

Fuchs, Sven; Keiler, Margreth; Zischg, Andreas

2016-04-01

The paper presents a nation-wide spatially explicit object-based assessment of buildings and citizens exposed to natural hazards in Austria, including river flooding, torrential flooding, and snow avalanches. The assessment was based on two different datasets, (a) hazard information providing input to the exposure of elements at risk, and (b) information on the building stock combined from different spatial data available on the national level. Hazard information was compiled from two different sources. For torrential flooding and snow avalanches available local-scale hazard maps were used, and for river flooding the results of the countrywide flood modelling eHORA were available. Information on the building stock contained information on the location and size of each building, as well as on the building category and the construction period. Additional information related to the individual floors, such as their height and net area, main purpose and configuration, was included for each property. Moreover, this dataset has an interface to the population register and allowed therefore retrieving the number of primary residents for each building. With the exception of sacral buildings, an economic module was used to compute the monetary value of buildings using (a) the information of the building register such as building type, number of storeys and utilisation, and (b) regionally averaged construction costs. It is shown that the repeatedly-stated assumption of increasing exposure due to continued population growth and related increase in assets has to be carefully evaluated by the local development of building stock. While some regions have shown a clearly above-average increase in assets, other regions were characterised by a below-average development. This mirrors the topography of the country, but also the different economic activities. While hotels and hostels are extraordinary prone to torrential flooding, commercial buildings as well as buildings used for

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.

Stochastic modeling of near-field exposure to parabens in personal care products

DEFF Research Database (Denmark)

Csiszar, Susan A.; Ernstoff, Alexi; Fantke, Peter

2017-01-01

Exposure assessment is a key step in determining risks to chemicals in consumer goods, including personal care products (PCPs). Exposure models can be used to estimate exposures to chemicals in the absence of biomonitoring data and as tools in chemical risk prioritization and screening. We apply...... a PCP exposure model based on the product intake fraction (PiF), which is defined as the fraction of chemical in a product that is taken in by the exposed population, to estimate chemical intake based on physicochemical properties and PCP usage characteristics. The PiF can be used to estimate route...... and pathway-specific exposures during both the use and disposal stages of a product. As a case study, we stochastically quantified population level exposures to parabens in PCPs, and compared estimates with biomarker values. We estimated exposure based on the usage of PCPs in the female US population, taking...

Assessment of risk of potential exposures on facilities industries; Estimativa do risco de exposicao potencial em instalacoes industriais

Energy Technology Data Exchange (ETDEWEB)

Leocadio, Joao Carlos

2007-03-15

This work develops a model to evaluate potential exposures on open facilities of industrial radiography in Brazil. This model will decisively contribute to optimize operational, radiological protection and safety procedures, to prevent radiation accidents and to reduce human errors in industrial radiography. The probabilistic safety assessment (PSA) methodology was very useful to assess potential exposures. The open facilities of industrial radiography were identified as the scenario to be analyzed in what concerns the evaluation of potential exposures, due to their high accidents indices. The results of the assessment of potential exposures confirm that the industrial radiography in Brazil is a high-risk practice as classified by the IAEA. The risk of potential exposure was estimated to be 40,5 x 10{sup -2} per year in Brazil, having as main consequences injuries to the workers' hands and arms. In the world scene, the consequences are worst, leading to fatalities of people, thus emphasizing the high risk of industrial radiography. (author)

Assessment of risk of potential exposures on facilities industries; Estimativa do risco de exposicao potencial em instalacoes industriais

Energy Technology Data Exchange (ETDEWEB)

Leocadio, Joao Carlos

2007-03-15

This work develops a model to evaluate potential exposures on open facilities of industrial radiography in Brazil. This model will decisively contribute to optimize operational, radiological protection and safety procedures, to prevent radiation accidents and to reduce human errors in industrial radiography. The probabilistic safety assessment (PSA) methodology was very useful to assess potential exposures. The open facilities of industrial radiography were identified as the scenario to be analyzed in what concerns the evaluation of potential exposures, due to their high accidents indices. The results of the assessment of potential exposures confirm that the industrial radiography in Brazil is a high-risk practice as classified by the IAEA. The risk of potential exposure was estimated to be 40,5 x 10{sup -2} per year in Brazil, having as main consequences injuries to the workers' hands and arms. In the world scene, the consequences are worst, leading to fatalities of people, thus emphasizing the high risk of industrial radiography. (author)

EPHECT III: Health risk assessment of exposure to household consumer products.

Science.gov (United States)

Trantallidi, M; Dimitroulopoulou, C; Wolkoff, P; Kephalopoulos, S; Carrer, P

2015-12-01

In the framework of the EU EPHECT project (Emissions, Exposure Patterns and Health Effects of Consumer Products in the EU), irritative and respiratory effects were assessed in relation to acute (30-min) and long-term (24-h) inhalation exposure to key and emerging indoor air pollutants emitted during household use of selected consumer products. A detailed Health Risk Assessment (HRA) was performed for five selected pollutants of respiratory health relevance, namely acrolein, formaldehyde, naphthalene, d-limonene and α-pinene. For each pollutant, the Critical Exposure Limit (CEL) was compared to indoor air concentrations and exposure estimates for the use of 15 selected consumer products by two population groups (housekeepers and retired people) in the four geographical regions of Europe (North, West, South, East), which were derived previously based on microenvironmental modelling. For the present HRA, health-based CELs were derived for certain compounds in case indoor air quality guidelines were not available by the World Health Organization for end-points relevant to the current study. For each pollutant, the highest indoor air concentrations in each microenvironment and exposure estimates across home microenvironments during the day were lower than the corresponding acute and long-term CELs. However, considerable contributions, especially to acute exposures, were obtained in some cases, such as formaldehyde emissions resulting from single product use of a floor cleaning agent (82% CEL), a candle (10% CEL) and an electric air freshener (17% CEL). Regarding multiple product use, the case of 30-min formaldehyde exposure reaching 34% CEL when eight product classes were used across home microenvironments, i.e. all-purpose/kitchen/floor cleaning agents, furniture/floor polish, combustible/electric air fresheners, and perfume, needs to be highlighted. Such estimated values should be evaluated with caution, as these may be attributed to the exposure scenarios

Assessing the risks from exposure to radon in dwellings

International Nuclear Information System (INIS)

Walsh, P.J.; Lowder, W.M.

1983-07-01

The factors used to assess the radiation dose and health risks from human exposure to radon in dwellings are critically reviewed in this summary. Sources of indoor radon and determinants of air concentrations and exposure levels are given as well as the uncertainties that exist in their formulation. Methods of assessing health effects from inhalation of radon and its progeny are discussed with emphasis on dosimetry of radon daughters and formulation of risk per dose values. Finally, methods of assessing risks for general population exposures to indoor radon concentrations are treated

Scientific Opinion on outline proposals for assessment of exposure of organisms to substances in soil

DEFF Research Database (Denmark)

Petersen, Annette

2010-01-01

appropriate for both conventional and reduced tillage in multi-year exposure calculations. The Panel proposes a tiered exposure assessment approach with four tiers. Tier 1 consists of a simple analytical model. Tier 2 consists of three scenarios (one for each of the three regulatory zones) that can be used...... for any annual crop in a zone. In Tiers 3 and 4, the exposure assessment can be refined considering the specific crops and/or substances with specific properties. The Panel proposes to develop guidance for estimating the degradation rate within the soil matrix from field persistence studies...

Exposure assessment strategies for non-routine work operations (NORWO)

International Nuclear Information System (INIS)

Lew, V.; Cohen, J.; Chiusano, S.; McGann, C.; McLouth, L.

1993-09-01

The DOE Office of Health and Office of Safety and Health Oversight are collaborating to address special problems related to assessment of worker exposures associated with nonroutine work operations (NORWO), such as hazardous waste operations. Both off ices have formed a single working group of industrial hygiene specialists from the DOE, fts contractors, and other interested organizations which held its first meeting July 1993. The DOE Canter of Excellence for Exposure Assessment, maintained at Lawrence Livermore National Laboratory, is assisting in developing reasonable policies and guidance on exposure assessment strategies for NORWO. The DOE EA Center will research this subject to assist the DOE in formulating guidance documents for conduct of EA for NORWO that are consistent with the DOE draft EAS technical standard. This report presents an outline for a section on NORWO intended for inclusion in the DOE technical guidance documents for EAS and Hazardous Waste Operations Emergency Response (HAZWOPER) currently under development by the DOE Industrial Hygiene Division (EH-412), and EM-23. Also presented is a review of the July 21--23 meeting and a proposed workplan for developing NORWO exposure assessment procedures. Appendices include: (A) David Weitzman's memo on NORWO, (B) Draft annotated outline of the technical standard for the Assessment of Employee Exposure to Hazardous Chemical Agents, (C) ORC proposed EAS standard, (D) program for the October 31--November 3, 1993 ACGIH Conference on Occupational Exposure Databases, (E) agenda for the July 15, 1993 DOE meeting on NORWO, (F) viewgraphs used in formal presentations at this meeting, (G) Hanford Exposure Assessment Program Plan, and (H) a list of attendees and invitees to the July DOE -- NORWO meeting

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

Exposure monitoring and risk assessment of biphenyl in the workplace.

Science.gov (United States)

Kim, Hyeon-Yeong; Shin, Sae-Mi; Ham, Miran; Lim, Cheol-Hong; Byeon, Sang-Hoon

2015-05-13

This study was performed to assess exposure to and the risk caused by biphenyl in the workplace. Biphenyl is widely used as a heat transfer medium and as an emulsifier and polish in industry. Vapor or high levels of dust inhalation and dermal exposure to biphenyl can cause eye inflammation, irritation of respiratory organs, and permanent lesions in the liver and nervous system. In this study, the workplace environment concentrations were assessed as central tendency exposure and reasonable maximum exposure and were shown to be 0.03 and 0.12 mg/m³, respectively. In addition, the carcinogenic risk of biphenyl as determined by risk assessment was 0.14 × 10⁻⁴ (central tendency exposure) and 0.56 × 10⁻⁴ (reasonable maximum exposure), which is below the acceptable risk value of 1.0 × 10⁻⁴. Furthermore, the central tendency exposure and reasonable maximum exposure hazard quotients were 0.01 and 0.06 for oral toxicity, 0.05 and 0.23 for inhalation toxicity, and 0.08 and 0.39 for reproduction toxicity, respectively, which are all lower than the acceptable hazard quotient of 1.0. Therefore, exposure to biphenyl was found to be safe in current workplace environments. Because occupational exposure limits are based on socioeconomic assessment, they are generally higher than true values seen in toxicity experiments. Based on the results of exposure monitoring of biphenyl, the current occupational exposure limits in Korea could be reviewed.

Exposure Monitoring and Risk Assessment of Biphenyl in the Workplace

Directory of Open Access Journals (Sweden)

Hyeon-Yeong Kim

2015-05-01

Full Text Available This study was performed to assess exposure to and the risk caused by biphenyl in the workplace. Biphenyl is widely used as a heat transfer medium and as an emulsifier and polish in industry. Vapor or high levels of dust inhalation and dermal exposure to biphenyl can cause eye inflammation, irritation of respiratory organs, and permanent lesions in the liver and nervous system. In this study, the workplace environment concentrations were assessed as central tendency exposure and reasonable maximum exposure and were shown to be 0.03 and 0.12 mg/m3, respectively. In addition, the carcinogenic risk of biphenyl as determined by risk assessment was 0.14 × 10−4 (central tendency exposure and 0.56 × 10−4 (reasonable maximum exposure, which is below the acceptable risk value of 1.0 × 10−4. Furthermore, the central tendency exposure and reasonable maximum exposure hazard quotients were 0.01 and 0.06 for oral toxicity, 0.05 and 0.23 for inhalation toxicity, and 0.08 and 0.39 for reproduction toxicity, respectively, which are all lower than the acceptable hazard quotient of 1.0. Therefore, exposure to biphenyl was found to be safe in current workplace environments. Because occupational exposure limits are based on socioeconomic assessment, they are generally higher than true values seen in toxicity experiments. Based on the results of exposure monitoring of biphenyl, the current occupational exposure limits in Korea could be reviewed.

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

Review of the chronic exposure pathways models in MACCS [MELCOR Accident Consequence Code System] and several other well-known probabilistic risk assessment models

International Nuclear Information System (INIS)

Tveten, U.

1990-06-01

The purpose of this report is to document the results of the work performed by the author in connection with the following task, performed for US Nuclear Regulatory Commission, (USNRC) Office of Nuclear Regulatory Research, Division of Systems Research: MACCS Chronic Exposure Pathway Models: Review the chronic exposure pathway models implemented in the MELCOR Accident Consequence Code System (MACCS) and compare those models to the chronic exposure pathway models implemented in similar codes developed in countries that are members of the OECD. The chronic exposures concerned are via: the terrestrial food pathways, the water pathways, the long-term groundshine pathway, and the inhalation of resuspended radionuclides pathway. The USNRC has indicated during discussions of the task that the major effort should be spent on the terrestrial food pathways. There is one chapter for each of the categories of chronic exposure pathways listed above

Stochastic health effects assessment due to short-term external exposure

International Nuclear Information System (INIS)

Raicevic, J.J.; Raskob, W.; Merkle, M.; Ninkovic, M.M.

2001-01-01

The new model for calculation of stochastic health effects is presented in this paper. The exposure pathways which are briefly considered are the short-term external exposure due to passage of the radioactive cloud (cloudshine) and the short-term external exposure due to radioactive material deposited on skin and clothes (skin contamination). The quantitative assessment of stochastic effects is expressed in numbers of deaths, which are given as a functions of the time at the accident, and age at death, what on the other side enables estimation of the number of deaths within the specified range of the time/age parameters. That means the model calculates the number of deaths within one particular year, summed up over all ages at deaths, or vice versa, it finds the number of deaths within the specified range of ages at death, summed up over all observation times. Results presented in this paper are implemented in the module LATEHEAL, which is incorporated in RODOS, a new European system for decision support for nuclear emergencies. (author)

Physiologically based pharmacokinetic toolkit to evaluate environmental exposures: Applications of the dioxin model to study real life exposures

Energy Technology Data Exchange (ETDEWEB)

Emond, Claude, E-mail: claude.emond@biosmc.com [BioSimulation Consulting Inc, Newark, DE (United States); Ruiz, Patricia; Mumtaz, Moiz [Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, Atlanta, GA (United States)

2017-01-15

Chlorinated dibenzo-p-dioxins (CDDs) are a series of mono- to octa-chlorinated homologous chemicals commonly referred to as polychlorinated dioxins. One of the most potent, well-known, and persistent member of this family is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). As part of translational research to make computerized models accessible to health risk assessors, we present a Berkeley Madonna recoded version of the human physiologically based pharmacokinetic (PBPK) model used by the U.S. Environmental Protection Agency (EPA) in the recent dioxin assessment. This model incorporates CYP1A2 induction, which is an important metabolic vector that drives dioxin distribution in the human body, and it uses a variable elimination half-life that is body burden dependent. To evaluate the model accuracy, the recoded model predictions were compared with those of the original published model. The simulations performed with the recoded model matched well with those of the original model. The recoded model was then applied to available data sets of real life exposure studies. The recoded model can describe acute and chronic exposures and can be useful for interpreting human biomonitoring data as part of an overall dioxin and/or dioxin-like compounds risk assessment. - Highlights: • The best available dioxin PBPK model for interpreting human biomonitoring data is presented. • The original PBPK model was recoded from acslX to the Berkeley Madonna (BM) platform. • Comparisons were made of the accuracy of the recoded model with the original model. • The model is a useful addition to the ATSDR's BM based PBPK toolkit that supports risk assessors. • The application of the model to real-life exposure data sets is illustrated.

The Health Impacts of Energy Policy Pathways in Ulaanbaatar, Mongolia: A Total Exposure Assessment

Science.gov (United States)

Hill, L. A.; Damdinsuren, Y.; Olkhanud, P. B.; Smith, K. R.; Turner, J. R.; Edwards, R.; Odsuren, M.; Ochir, C.

2015-12-01

Ulaanbaatar is home to nearly half of Mongolia's 2.8 million residents. The city's rapid growth, frigid winters, valley topography, and reliance on coal-fired stoves have led to some of the worst winter pollution levels in the world. To better understand this issue, we modeled integrated PM2.5exposures and related health impacts for various city-wide heating policies through 2024. This assessment is one of the first to employ a total exposure approach and results of the 2014 Comparative Risk Assessments of the Global Burden of Disease Project (CRA/GBD) in a policy-relevant energy study. Emissions related to heating, traffic, and power generation were considered under Business as Usual, Moderate Improvement, and Max Improvement scenarios. Calibrated outdoor models were combined with indoor models, local infiltration and time activity estimates, and demographic projections to estimate PM2.5exposures in 2014 and 2024. Indoor exposures were assigned by heating type, home type, and smoking status; outdoor exposures were assigned through geocoding. Population average annual exposures were calculated and applied to local disease rates and integrated exposure-response curves (2014 CRA/GBD) to arrive at annual projections of premature deaths and DALYs. We estimate 2014 annual average exposures at 68 μg/m3, dictated almost exclusively by indoor winter exposures. Under current trends, annual exposures increase 10% to 75 μg/m3 in 2024. This is in stark contrast to the moderate and max improvement scenarios, which lead to 2024 annual exposures that are 31%, and 68% lower, respectively. Under the Moderate scenario, 2024 per capita annual DALY and death burdens drop 26% and 22%, respectively, from 2014 levels. Under the Max scenario, 2024 per capita annual DALY and death burdens drop 71% and 66%, respectively, from 2014. SHS becomes a major contributor as emissions from other sectors decrease. Reductions are dominated by cardiovascular and lower respiratory diseases in children.

Modeling population exposures to silver nanoparticles present in consumer products

Science.gov (United States)

Royce, Steven G.; Mukherjee, Dwaipayan; Cai, Ting; Xu, Shu S.; Alexander, Jocelyn A.; Mi, Zhongyuan; Calderon, Leonardo; Mainelis, Gediminas; Lee, KiBum; Lioy, Paul J.; Tetley, Teresa D.; Chung, Kian Fan; Zhang, Junfeng; Georgopoulos, Panos G.

2014-11-01

Exposures of the general population to manufactured nanoparticles (MNPs) are expected to keep rising due to increasing use of MNPs in common consumer products (PEN 2014). The present study focuses on characterizing ambient and indoor population exposures to silver MNPs (nAg). For situations where detailed, case-specific exposure-related data are not available, as in the present study, a novel tiered modeling system, Prioritization/Ranking of Toxic Exposures with GIS (geographic information system) Extension (PRoTEGE), has been developed: it employs a product life cycle analysis (LCA) approach coupled with basic human life stage analysis (LSA) to characterize potential exposures to chemicals of current and emerging concern. The PRoTEGE system has been implemented for ambient and indoor environments, utilizing available MNP production, usage, and properties databases, along with laboratory measurements of potential personal exposures from consumer spray products containing nAg. Modeling of environmental and microenvironmental levels of MNPs employs probabilistic material flow analysis combined with product LCA to account for releases during manufacturing, transport, usage, disposal, etc. Human exposure and dose characterization further employ screening microenvironmental modeling and intake fraction methods combined with LSA for potentially exposed populations, to assess differences associated with gender, age, and demographics. Population distributions of intakes, estimated using the PRoTEGE framework, are consistent with published individual-based intake estimates, demonstrating that PRoTEGE is capable of capturing realistic exposure scenarios for the US population. Distributions of intakes are also used to calculate biologically relevant population distributions of uptakes and target tissue doses through human airway dosimetry modeling that takes into account product MNP size distributions and age-relevant physiological parameters.

Testing of an accident consequence assessment model using field data

International Nuclear Information System (INIS)

Homma, Toshimitsu; Matsubara, Takeshi; Tomita, Kenichi

2007-01-01

This paper presents the results obtained from the application of an accident consequence assessment model, OSCAAR to the Iput dose reconstruction scenario of BIOMASS and also to the Chernobyl 131 I fallout scenario of EMRAS, both organized by International Atomic Energy Agency. The Iput Scenario deals with 137 Cs contamination of the catchment basin and agricultural area in the Bryansk Region of Russia, which was heavily contaminated after the Chernobyl accident. This exercise was used to test the chronic exposure pathway models in OSCAAR with actual measurements and to identify the most important sources of uncertainty with respect to each part of the assessment. The OSCAAR chronic exposure pathway models had some limitations but the refined model, COLINA almost successfully reconstructed the whole 10-year time course of 137 Cs activity concentrations in most requested types of agricultural products and natural foodstuffs. The Plavsk scenario provides a good opportunity to test not only the food chain transfer model of 131 I but also the method of assessing 131 I thyroid burden. OSCAAR showed in general good capabilities for assessing the important 131 I exposure pathways. (author)

A dynamic urban air pollution population exposure assessment study using model and population density data derived by mobile phone traffic

Science.gov (United States)

Gariazzo, Claudio; Pelliccioni, Armando; Bolignano, Andrea

2016-04-01

A dynamic city-wide air pollution exposure assessment study has been carried out for the urban population of Rome, Italy, by using time resolved population distribution maps, derived by mobile phone traffic data, and modelled air pollutants (NO2, O3 and PM2.5) concentrations obtained by an integrated air dispersion modelling system. More than a million of persons were tracked during two months (March and April 2015) for their position within the city and its surroundings areas, with a time resolution of 15 min and mapped over an irregular grid system with a minimum resolution of 0.26 × 0.34 Km2. In addition, demographics information (as gender and age ranges) were available in a separated dataset not connected with the total population one. Such BigData were matched in time and space with air pollution model results and then used to produce hourly and daily resolved cumulative population exposures during the studied period. A significant mobility of population was identified with higher population densities in downtown areas during daytime increasing of up to 1000 people/Km2 with respect to nigh-time one, likely produced by commuters, tourists and working age population. Strong variability (up to ±50% for NO2) of population exposures were detected as an effect of both mobility and time/spatial changing in pollutants concentrations. A comparison with the correspondent stationary approach based on National Census data, allows detecting the inability of latter in estimating the actual variability of population exposure. Significant underestimations of the amount of population exposed to daily PM2.5 WHO guideline was identified for the Census approach. Very small differences (up to a few μg/m3) on exposure were detected for gender and age ranges population classes.

Non-ionizing electromagnetic exposure assessment and dosimetry

International Nuclear Information System (INIS)

Paulsson, L.E.

1992-11-01

A comprehensive literature survey of advancements in the area 'human exposure assessment and dosimetry' for the years 1988-1992 has been performed by the author and published elsewhere. In the present report that material has been complemented with a historical background and a thorough description of the physical principles behind the methods and techniques. The report covers strategies, principles, methods, limitations and future developments for the area of human exposure assessment and dosimetry of electromagnetic fields form extremely low frequencies up to and including microwaves

DREAM: a method for semi-quantitative dermal exposure assessment

NARCIS (Netherlands)

Wendel de Joode, B. van; Brouwer, D.H.; Kromhout, H.; Hemmen, J.J. van

2003-01-01

This paper describes a new method (DREAM) for structured, semi-quantitative dermal exposure assessment for chemical or biological agents that can be used in occupational hygiene or epidemiology. It is anticipated that DREAM could serve as an initial assessment of dermal exposure, amongst others,

Assessing frost damages using dynamic models in walnut trees: exposure rather than vulnerability controls frost risks.

Science.gov (United States)

Guillaume, Charrier; Isabelle, Chuine; Marc, Bonhomme; Thierry, Améglio

2018-05-01

Frost damages develop when exposure overtakes frost vulnerability. Frost risk assessment therefore needs dynamic simulation of frost hardiness using temperature and photoperiod in interaction with developmental stage. Two models, including or not the effect of photoperiod, were calibrated using five years of frost hardiness monitoring (2007-2012), in two locations (low and high elevation) for three walnut genotypes with contrasted phenology and maximum hardiness (Juglans regia cv Franquette, J. regia × nigra 'Early' and 'Late'). The photothermal model predicted more accurate values for all genotypes (efficiency = 0.879; Root Mean Standard Error Predicted (RMSEP) = 2.55 °C) than the thermal model (efficiency = 0.801; RMSEP = 3.24 °C). Predicted frost damages were strongly correlated to minimum temperature of the freezing events (ρ = -0.983) rather than actual frost hardiness (ρ = -0.515), or ratio of phenological stage completion (ρ = 0.336). Higher frost risks are consequently predicted during winter, at high elevation, whereas spring is only risky at low elevation in early genotypes exhibiting faster dehardening rate. However, early frost damages, although of lower value, may negatively affect fruit production the subsequent year (R 2  = 0.381, P = 0.057). These results highlight the interacting pattern between frost exposure and vulnerability at different scales and the necessity of intra-organ studies to understand the time course of frost vulnerability in flower buds along the winter. © 2017 John Wiley & Sons Ltd.

Exposure assessment of tetrafluoroethylene and ammonium perfluorooctanoate 1951-2002.

Science.gov (United States)

Sleeuwenhoek, Anne; Cherrie, John W

2012-03-01

To develop a method to reconstruct exposure to tetrafluoroethylene (TFE) and ammonium perfluorooctanoate (APFO) in plants producing polytetrafluoroethylene (PTFE) in the absence of suitable objective measurements. These data were used to inform an epidemiological study being carried out to investigate possible risks in workers employed in the manufacture of PTFE and to study trends in exposure over time. For each plant, detailed descriptions of all occupational titles, including tasks and changes over time, were obtained during semi-structured interviews with key plant personnel. A semi-quantitative assessment method was used to assess inhalation exposure to TFE and inhalation plus dermal exposure to APFO. Temporal trends in exposure to TFE and APFO were investigated. In each plant the highest exposures for both TFE and APFO occurred in the polymerisation area. Due to the introduction of control measures, increasing process automation and other improvements, exposures generally decreased over time. In the polymerisation area, the annual decline in exposure to TFE varied by plant from 3.8 to 5.7% and for APFO from 2.2 to 5.5%. A simple method for assessing exposure was developed which used detailed process information and job descriptions to estimate average annual TFE and APFO exposure on an arbitrary semi-quantitative scale. These semi-quantitative estimates are sufficient to identify relative differences in exposure for the epidemiological study and should good data become available, they could be used to provide quantitative estimates for all plants across the whole period of operation. This journal is © The Royal Society of Chemistry 2012

Source attribution of human campylobacteriosis at the point of exposure by combining comparative exposure assessment and subtype comparison based on comparative genomic fingerprinting.

Directory of Open Access Journals (Sweden)

André Ravel

Full Text Available Human campylobacteriosis is a common zoonosis with a significant burden in many countries. Its prevention is difficult because humans can be exposed to Campylobacter through various exposures: foodborne, waterborne or by contact with animals. This study aimed at attributing campylobacteriosis to sources at the point of exposure. It combined comparative exposure assessment and microbial subtype comparison with subtypes defined by comparative genomic fingerprinting (CGF. It used isolates from clinical cases and from eight potential exposure sources (chicken, cattle and pig manure, retail chicken, beef, pork and turkey meat, and surface water collected within a single sentinel site of an integrated surveillance system for enteric pathogens in Canada. Overall, 1518 non-human isolates and 250 isolates from domestically-acquired human cases were subtyped and their subtype profiles analyzed for source attribution using two attribution models modified to include exposure. Exposure values were obtained from a concurrent comparative exposure assessment study undertaken in the same area. Based on CGF profiles, attribution was possible for 198 (79% human cases. Both models provide comparable figures: chicken meat was the most important source (65-69% of attributable cases whereas exposure to cattle (manure ranked second (14-19% of attributable cases, the other sources being minor (including beef meat. In comparison with other attributions conducted at the point of production, the study highlights the fact that Campylobacter transmission from cattle to humans is rarely meat borne, calling for a closer look at local transmission from cattle to prevent campylobacteriosis, in addition to increasing safety along the chicken supply chain.

Source attribution of human campylobacteriosis at the point of exposure by combining comparative exposure assessment and subtype comparison based on comparative genomic fingerprinting.

Science.gov (United States)

Ravel, André; Hurst, Matt; Petrica, Nicoleta; David, Julie; Mutschall, Steven K; Pintar, Katarina; Taboada, Eduardo N; Pollari, Frank

2017-01-01

Human campylobacteriosis is a common zoonosis with a significant burden in many countries. Its prevention is difficult because humans can be exposed to Campylobacter through various exposures: foodborne, waterborne or by contact with animals. This study aimed at attributing campylobacteriosis to sources at the point of exposure. It combined comparative exposure assessment and microbial subtype comparison with subtypes defined by comparative genomic fingerprinting (CGF). It used isolates from clinical cases and from eight potential exposure sources (chicken, cattle and pig manure, retail chicken, beef, pork and turkey meat, and surface water) collected within a single sentinel site of an integrated surveillance system for enteric pathogens in Canada. Overall, 1518 non-human isolates and 250 isolates from domestically-acquired human cases were subtyped and their subtype profiles analyzed for source attribution using two attribution models modified to include exposure. Exposure values were obtained from a concurrent comparative exposure assessment study undertaken in the same area. Based on CGF profiles, attribution was possible for 198 (79%) human cases. Both models provide comparable figures: chicken meat was the most important source (65-69% of attributable cases) whereas exposure to cattle (manure) ranked second (14-19% of attributable cases), the other sources being minor (including beef meat). In comparison with other attributions conducted at the point of production, the study highlights the fact that Campylobacter transmission from cattle to humans is rarely meat borne, calling for a closer look at local transmission from cattle to prevent campylobacteriosis, in addition to increasing safety along the chicken supply chain.

A class of non-linear exposure-response models suitable for health impact assessment applicable to large cohort studies of ambient air pollution.

Science.gov (United States)

Nasari, Masoud M; Szyszkowicz, Mieczysław; Chen, Hong; Crouse, Daniel; Turner, Michelle C; Jerrett, Michael; Pope, C Arden; Hubbell, Bryan; Fann, Neal; Cohen, Aaron; Gapstur, Susan M; Diver, W Ryan; Stieb, David; Forouzanfar, Mohammad H; Kim, Sun-Young; Olives, Casey; Krewski, Daniel; Burnett, Richard T

2016-01-01

The effectiveness of regulatory actions designed to improve air quality is often assessed by predicting changes in public health resulting from their implementation. Risk of premature mortality from long-term exposure to ambient air pollution is the single most important contributor to such assessments and is estimated from observational studies generally assuming a log-linear, no-threshold association between ambient concentrations and death. There has been only limited assessment of this assumption in part because of a lack of methods to estimate the shape of the exposure-response function in very large study populations. In this paper, we propose a new class of variable coefficient risk functions capable of capturing a variety of potentially non-linear associations which are suitable for health impact assessment. We construct the class by defining transformations of concentration as the product of either a linear or log-linear function of concentration multiplied by a logistic weighting function. These risk functions can be estimated using hazard regression survival models with currently available computer software and can accommodate large population-based cohorts which are increasingly being used for this purpose. We illustrate our modeling approach with two large cohort studies of long-term concentrations of ambient air pollution and mortality: the American Cancer Society Cancer Prevention Study II (CPS II) cohort and the Canadian Census Health and Environment Cohort (CanCHEC). We then estimate the number of deaths attributable to changes in fine particulate matter concentrations over the 2000 to 2010 time period in both Canada and the USA using both linear and non-linear hazard function models.

Integration of Probabilistic Exposure Assessment and Probabilistic Hazard Characterization

NARCIS (Netherlands)

Voet, van der H.; Slob, W.

2007-01-01

A method is proposed for integrated probabilistic risk assessment where exposure assessment and hazard characterization are both included in a probabilistic way. The aim is to specify the probability that a random individual from a defined (sub)population will have an exposure high enough to cause a

Assessing the reliability of dose coefficients for exposure to radioiodine by members of the public, accounting for dosimetric and risk model uncertainties.

Science.gov (United States)

Puncher, M; Zhang, W; Harrison, J D; Wakeford, R

2017-06-26

Assessments of risk to a specific population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficients used as a radiation protection device for the specified exposure pathway. An estimate of the uncertainty on the associated risk is important for informing judgments on reliability; a derived uncertainty factor, UF, is an estimate of the 95% probable geometric difference between the best risk estimate and the nominal risk and is a useful tool for making this assessment. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to radioiodine by members of the public, specifically 1, 10 and 20-year old females from the population of England and Wales. Best estimates of thyroid cancer incidence risk (lifetime attributable risk) are calculated for ingestion or inhalation of 129 I and 131 I, accounting for uncertainties in biokinetic model and cancer risk model parameter values. These estimates are compared with the equivalent ICRP derived nominal age-, sex- and population-averaged estimates of excess thyroid cancer incidence to obtain UFs. Derived UF values for ingestion or inhalation of 131 I for 1 year, 10-year and 20-year olds are around 28, 12 and 6, respectively, when compared with ICRP Publication 103 nominal values, and 9, 7 and 14, respectively, when compared with ICRP Publication 60 values. Broadly similar results were obtained for 129 I. The uncertainties on risk estimates are largely determined by uncertainties on risk model parameters rather than uncertainties on biokinetic model parameters. An examination of the sensitivity of the results to the risk models and populations used in the calculations show variations in the central estimates of risk of a factor of around 2-3. It is assumed that the direct proportionality of excess thyroid cancer

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)

Modelling of aircrew radiation exposure during solar particle events

Science.gov (United States)

Al Anid, Hani Khaled

show a very different response during anisotropic events, leading to variations in aircrew radiation doses that may be significant for dose assessment. To estimate the additional exposure due to solar flares, a model was developed using a Monte-Carlo radiation transport code, MCNPX. The model transports an extrapolated particle spectrum based on satellite measurements through the atmosphere using the MCNPX analysis. This code produces the estimated flux at a specific altitude where radiation dose conversion coefficients are applied to convert the particle flux into effective and ambient dose-equivalent rates. A cut-off rigidity model accounts for the shielding effects of the Earth's magnetic field. Comparisons were made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during Ground Level Enhancements 60 and 65. An anisotropy analysis that uses neutron monitor responses and the pitch angle distribution of energetic solar particles was used to identify particle anisotropy for a solar event in December 2006. In anticipation of future commercial use, a computer code has been developed to implement the radiation dose assessment model for routine analysis. Keywords: Radiation Dosimetry, Radiation Protection, Space Physics.

Low Pathogenic Avian Influenza Exposure Risk Assessment in Australian Commercial Chicken Farms

Science.gov (United States)

Scott, Angela Bullanday; Toribio, Jenny-Ann; Singh, Mini; Groves, Peter; Barnes, Belinda; Glass, Kathryn; Moloney, Barbara; Black, Amanda; Hernandez-Jover, Marta

2018-01-01

This study investigated the pathways of exposure to low pathogenic avian influenza (LPAI) virus among Australian commercial chicken farms and estimated the likelihood of this exposure occurring using scenario trees and a stochastic modeling approach following the World Organization for Animal Health methodology for risk assessment. Input values for the models were sourced from scientific literature and an on-farm survey conducted during 2015 and 2016 among Australian commercial chicken farms located in New South Wales and Queensland. Outputs from the models revealed that the probability of a first LPAI virus exposure to a chicken in an Australian commercial chicken farms from one wild bird at any point in time is extremely low. A comparative assessment revealed that across the five farm types (non-free-range meat chicken, free-range meat chicken, cage layer, barn layer, and free range layer farms), free-range layer farms had the highest probability of exposure (7.5 × 10−4; 5% and 95%, 5.7 × 10−4—0.001). The results indicate that the presence of a large number of wild birds on farm is required for exposure to occur across all farm types. The median probability of direct exposure was highest in free-range farm types (5.6 × 10−4 and 1.6 × 10−4 for free-range layer and free-range meat chicken farms, respectively) and indirect exposure was highest in non-free-range farm types (2.7 × 10−4, 2.0 × 10−4, and 1.9 × 10−4 for non-free-range meat chicken, cage layer, and barn layer farms, respectively). The probability of exposure was found to be lowest in summer for all farm types. Sensitivity analysis revealed that the proportion of waterfowl among wild birds on the farm, the presence of waterfowl in the range and feed storage areas, and the prevalence of LPAI in wild birds are the most influential parameters for the probability of Australian commercial chicken farms being exposed to avian influenza (AI) virus. These results

Low Pathogenic Avian Influenza Exposure Risk Assessment in Australian Commercial Chicken Farms.

Science.gov (United States)

Scott, Angela Bullanday; Toribio, Jenny-Ann; Singh, Mini; Groves, Peter; Barnes, Belinda; Glass, Kathryn; Moloney, Barbara; Black, Amanda; Hernandez-Jover, Marta

2018-01-01

This study investigated the pathways of exposure to low pathogenic avian influenza (LPAI) virus among Australian commercial chicken farms and estimated the likelihood of this exposure occurring using scenario trees and a stochastic modeling approach following the World Organization for Animal Health methodology for risk assessment. Input values for the models were sourced from scientific literature and an on-farm survey conducted during 2015 and 2016 among Australian commercial chicken farms located in New South Wales and Queensland. Outputs from the models revealed that the probability of a first LPAI virus exposure to a chicken in an Australian commercial chicken farms from one wild bird at any point in time is extremely low. A comparative assessment revealed that across the five farm types (non-free-range meat chicken, free-range meat chicken, cage layer, barn layer, and free range layer farms), free-range layer farms had the highest probability of exposure (7.5 × 10 -4 ; 5% and 95%, 5.7 × 10 -4 -0.001). The results indicate that the presence of a large number of wild birds on farm is required for exposure to occur across all farm types. The median probability of direct exposure was highest in free-range farm types (5.6 × 10 -4 and 1.6 × 10 -4 for free-range layer and free-range meat chicken farms, respectively) and indirect exposure was highest in non-free-range farm types (2.7 × 10 -4 , 2.0 × 10 -4 , and 1.9 × 10 -4 for non-free-range meat chicken, cage layer, and barn layer farms, respectively). The probability of exposure was found to be lowest in summer for all farm types. Sensitivity analysis revealed that the proportion of waterfowl among wild birds on the farm, the presence of waterfowl in the range and feed storage areas, and the prevalence of LPAI in wild birds are the most influential parameters for the probability of Australian commercial chicken farms being exposed to avian influenza (AI) virus. These results

Low Pathogenic Avian Influenza Exposure Risk Assessment in Australian Commercial Chicken Farms

Directory of Open Access Journals (Sweden)

Angela Bullanday Scott

2018-04-01

Full Text Available This study investigated the pathways of exposure to low pathogenic avian influenza (LPAI virus among Australian commercial chicken farms and estimated the likelihood of this exposure occurring using scenario trees and a stochastic modeling approach following the World Organization for Animal Health methodology for risk assessment. Input values for the models were sourced from scientific literature and an on-farm survey conducted during 2015 and 2016 among Australian commercial chicken farms located in New South Wales and Queensland. Outputs from the models revealed that the probability of a first LPAI virus exposure to a chicken in an Australian commercial chicken farms from one wild bird at any point in time is extremely low. A comparative assessment revealed that across the five farm types (non-free-range meat chicken, free-range meat chicken, cage layer, barn layer, and free range layer farms, free-range layer farms had the highest probability of exposure (7.5 × 10−4; 5% and 95%, 5.7 × 10−4—0.001. The results indicate that the presence of a large number of wild birds on farm is required for exposure to occur across all farm types. The median probability of direct exposure was highest in free-range farm types (5.6 × 10−4 and 1.6 × 10−4 for free-range layer and free-range meat chicken farms, respectively and indirect exposure was highest in non-free-range farm types (2.7 × 10−4, 2.0 × 10−4, and 1.9 × 10−4 for non-free-range meat chicken, cage layer, and barn layer farms, respectively. The probability of exposure was found to be lowest in summer for all farm types. Sensitivity analysis revealed that the proportion of waterfowl among wild birds on the farm, the presence of waterfowl in the range and feed storage areas, and the prevalence of LPAI in wild birds are the most influential parameters for the probability of Australian commercial chicken farms being exposed to avian influenza (AI virus

A geographic approach to modelling human exposure to traffic air pollution using GIS

Energy Technology Data Exchange (ETDEWEB)

Solvang Jensen, S.

1998-10-01

A new exposure model has been developed that is based on a physical, single media (air) and single source (traffic) micro environmental approach that estimates traffic related exposures geographically with the postal address as exposure indicator. The micro environments: residence, workplace and street (road user exposure) may be considered. The model estimates outdoor levels for selected ambient air pollutants (benzene, CO, NO{sub 2} and O{sub 3}). The influence of outdoor air pollution on indoor levels can be estimated using average (I/O-ratios. The model has a very high spatial resolution (the address), a high temporal resolution (one hour) and may be used to predict past, present and future exposures. The model may be used for impact assessment of control measures provided that the changes to the model inputs are obtained. The exposure model takes advantage of a standard Geographic Information System (GIS) (ArcView and Avenue) for generation of inputs, for visualisation of input and output, and uses available digital maps, national administrative registers and a local traffic database, and the Danish Operational Street Pollution Model (OSPM). The exposure model presents a new approach to exposure determination by integration of digital maps, administrative registers, a street pollution model and GIS. New methods have been developed to generate the required input parameters for the OSPM model: to geocode buildings using cadastral maps and address points, to automatically generate street configuration data based on digital maps, the BBR and GIS; to predict the temporal variation in traffic and related parameters; and to provide hourly background levels for the OSPM model. (EG) 109 refs.

Meta-modeling of the pesticide fate model MACRO for groundwater exposure assessments using artificial neural networks

Science.gov (United States)

Stenemo, Fredrik; Lindahl, Anna M. L.; Gärdenäs, Annemieke; Jarvis, Nicholas

2007-08-01

Several simple index methods that use easily accessible data have been developed and included in decision-support systems to estimate pesticide leaching across larger areas. However, these methods often lack important process descriptions (e.g. macropore flow), which brings into question their reliability. Descriptions of macropore flow have been included in simulation models, but these are too complex and demanding for spatial applications. To resolve this dilemma, a neural network simulation meta-model of the dual-permeability macropore flow model MACRO was created for pesticide groundwater exposure assessment. The model was parameterized using pedotransfer functions that require as input the clay and sand content of the topsoil and subsoil, and the topsoil organic carbon content. The meta-model also requires the topsoil pesticide half-life and the soil organic carbon sorption coefficient as input. A fully connected feed-forward multilayer perceptron classification network with two hidden layers, linked to fully connected feed-forward multilayer perceptron neural networks with one hidden layer, trained on sub-sets of the target variable, was shown to be a suitable meta-model for the intended purpose. A Fourier amplitude sensitivity test showed that the model output (the 80th percentile average yearly pesticide concentration at 1 m depth for a 20 year simulation period) was sensitive to all input parameters. The two input parameters related to pesticide characteristics (i.e. soil organic carbon sorption coefficient and topsoil pesticide half-life) were the most influential, but texture in the topsoil was also quite important since it was assumed to control the mass exchange coefficient that regulates the strength of macropore flow. This is in contrast to models based on the advection-dispersion equation where soil texture is relatively unimportant. The use of the meta-model is exemplified with a case-study where the spatial variability of pesticide leaching is

Biological exposure assessment to tetrachloroethylene for workers in the dry cleaning industry

Directory of Open Access Journals (Sweden)

Ashley David L

2008-04-01

Full Text Available Abstract Background The purpose of this study was to assess the feasibility of conducting biological tetrachloroethylene (perchloroethylene, PCE exposure assessments of dry cleaning employees in conjunction with evaluation of possible PCE health effects. Methods Eighteen women from four dry cleaning facilities in southwestern Ohio were monitored in a pilot study of workers with PCE exposure. Personal breathing zone samples were collected from each employee on two consecutive work days. Biological monitoring included a single measurement of PCE in blood and multiple measurements of pre- and post-shift PCE in exhaled breath and trichloroacetic acid (TCA in urine. Results Post-shift PCE in exhaled breath gradually increased throughout the work week. Statistically significant correlations were observed among the exposure indices. Decreases in PCE in exhaled breath and TCA in urine were observed after two days without exposure to PCE. A mixed-effects model identified statistically significant associations between PCE in exhaled breath and airborne PCE time weighted average (TWA after adjusting for a random participant effect and fixed effects of time and body mass index. Conclusion Although comprehensive, our sampling strategy was challenging to implement due to fluctuating work schedules and the number (pre- and post-shift on three consecutive days and multiplicity (air, blood, exhaled breath, and urine of samples collected. PCE in blood is the preferred biological index to monitor exposures, but may make recruitment difficult. PCE TWA sampling is an appropriate surrogate, although more field intensive. Repeated measures of exposure and mixed-effects modeling may be required for future studies due to high within-subject variability. Workers should be monitored over a long enough period of time to allow the use of a lag term.

The Future of Exposure Assessment: Perspectives from the ...

Science.gov (United States)

The British Occupational Hygiene Society, in collaboration with the Institute of Occupational Medicine, the University of Manchester, the UK Health and Safety Executive, and the University of Aberdeen hosted the 7th International Conference on the Science of Exposure Assessment (X2012) on 2 July–5 July 2012 in Edinburgh, UK. The conference ended with a special session at which invited speakers from government, industry, independent research institutes, and academia were asked to reflect on the conference and discuss what may now constitute the important highlights or drivers of future exposure assessment research. This article summarizes these discussions with respect to current and future technical and methodological developments. For the exposure science community to continue to have an impact in protecting public health, additional efforts need to be made to improve partnerships and cross-disciplinary collaborations, although it is equally important to ensure that the traditional occupational exposure themes are still covered as these issues are becoming increasingly important in the developing world. To facilitate this the ‘X’ conferences should continue to retain a holistic approach to occupational and non-occupational exposures and should actively pursue collaborations with other disciplines and professional organizations to increase the presence of consumer and environmental exposure scientists. The National Exposure Research Laboratory′s (NERL′

Uncertainties in radioecological assessment models

International Nuclear Information System (INIS)

Hoffman, F.O.; Miller, C.W.; Ng, Y.C.

1983-01-01

Environmental radiological assessments rely heavily on the use of mathematical models. The predictions of these models are inherently uncertain because models are inexact representations of real systems. The major sources of this uncertainty are related to bias in model formulation and imprecision in parameter estimation. The magnitude of uncertainty is a function of the questions asked of the model and the specific radionuclides and exposure pathways of dominant importance. It is concluded that models developed as research tools should be distinguished from models developed for assessment applications. Furthermore, increased model complexity does not necessarily guarantee increased accuracy. To improve the realism of assessment modeling, stochastic procedures are recommended that translate uncertain parameter estimates into a distribution of predicted values. These procedures also permit the importance of model parameters to be ranked according to their relative contribution to the overall predicted uncertainty. Although confidence in model predictions can be improved through site-specific parameter estimation and increased model validation, health risk factors and internal dosimetry models will probably remain important contributors to the amount of uncertainty that is irreducible. 41 references, 4 figures, 4 tables

Estimating the value of a Country's built assets: investment-based exposure modelling for global risk assessment

Science.gov (United States)

Daniell, James; Pomonis, Antonios; Gunasekera, Rashmin; Ishizawa, Oscar; Gaspari, Maria; Lu, Xijie; Aubrecht, Christoph; Ungar, Joachim

2017-04-01

In order to quantify disaster risk, there is a demand and need for determining consistent and reliable economic value of built assets at national or sub national level exposed to natural hazards. The value of the built stock in the context of a city or a country is critical for risk modelling applications as it allows for the upper bound in potential losses to be established. Under the World Bank probabilistic disaster risk assessment - Country Disaster Risk Profiles (CDRP) Program and rapid post-disaster loss analyses in CATDAT, key methodologies have been developed that quantify the asset exposure of a country. In this study, we assess the complementary methods determining value of building stock through capital investment data vs aggregated ground up values based on built area and unit cost of construction analyses. Different approaches to modelling exposure around the world, have resulted in estimated values of built assets of some countries differing by order(s) of magnitude. Using the aforementioned methodology of comparing investment data based capital stock and bottom-up unit cost of construction values per square meter of assets; a suitable range of capital stock estimates for built assets have been created. A blind test format was undertaken to compare the two types of approaches from top-down (investment) and bottom-up (construction cost per unit), In many cases, census data, demographic, engineering and construction cost data are key for bottom-up calculations from previous years. Similarly for the top-down investment approach, distributed GFCF (Gross Fixed Capital Formation) data is also required. Over the past few years, numerous studies have been undertaken through the World Bank Caribbean and Central America disaster risk assessment program adopting this methodology initially developed by Gunasekera et al. (2015). The range of values of the building stock is tested for around 15 countries. In addition, three types of costs - Reconstruction cost

Assessment of genetic risk for human exposure to radiation. State of the art

International Nuclear Information System (INIS)

Shevchenko, V.A.

2000-01-01

Historical aspects of the conception of genetic risk of human irradiation for recent 40 years. Methodology of assessing the genetic risk of radiation exposure is based on the concept of hitting the target. To predict genetic risk of irradiation, the direct and indirect methods of assessment, extrapolation, integral and populational criteria of risk analysis is widely used. Combination of these methods permits to calculate the risk from human exposure on the basis of data obtained for mice. Method of doubling dose based on determination of the dose doubling the level of natural mutational process in humans is the main one used to predict the genetic risk. Till 1972 the main model for assessing the genetic risk was the human/mouse model (the use of data on the spontaneous human variability and data on the frequency of induced mutations in mice). In the period from 1972 till 1994 the mouse/mouse model was intensively elaborated in many laboratories. This model was also used in this period to analyse the genetic risk of human irradiation. Recent achievements associated with the study of molecular nature of many hereditary human diseases as well as the criticism of a fundamental principles of the mouse/mouse model for estimating the genetic risk on a new basis. Estimates of risk for the different classes of genetic diseases have been obtained using the doubling-dose method [ru

Quantitative self-assessment of exposure to solvents among shoe repair men

NARCIS (Netherlands)

Hertsenberg, S.; Brouwer, D.; Lurvink, M.; Rubingh, C.; Rijnders, E.; Tielemans, E.

2007-01-01

Self-assessment of exposure (SAE) refers to any exposure assessment methodology wherein the worker takes an active role in establishing his or her exposure status. The objective of this study was to investigate the reliability and feasibility of SAE approaches among shoe repair workers collecting

Technical Overview of Ecological Risk Assessment - Analysis Phase: Exposure Characterization

Science.gov (United States)

Exposure Characterization is the second major component of the analysis phase of a risk assessment. For a pesticide risk assessment, the exposure characterization describes the potential or actual contact of a pesticide with a plant, animal, or media.

Spatial and Temporal Dynamics in Air Pollution Exposure Assessment

Science.gov (United States)

Dias, Daniela; Tchepel, Oxana

2018-01-01

Analyzing individual exposure in urban areas offers several challenges where both the individual’s activities and air pollution levels demonstrate a large degree of spatial and temporal dynamics. This review article discusses the concepts, key elements, current developments in assessing personal exposure to urban air pollution (seventy-two studies reviewed) and respective advantages and disadvantages. A new conceptual structure to organize personal exposure assessment methods is proposed according to two classification criteria: (i) spatial-temporal variations of individuals’ activities (point-fixed or trajectory based) and (ii) characterization of air quality (variable or uniform). This review suggests that the spatial and temporal variability of urban air pollution levels in combination with indoor exposures and individual’s time-activity patterns are key elements of personal exposure assessment. In the literature review, the majority of revised studies (44 studies) indicate that the trajectory based with variable air quality approach provides a promising framework for tackling the important question of inter- and intra-variability of individual exposure. However, future quantitative comparison between the different approaches should be performed, and the selection of the most appropriate approach for exposure quantification should take into account the purpose of the health study. This review provides a structured basis for the intercomparing of different methodologies and to make their advantages and limitations more transparent in addressing specific research objectives. PMID:29558426

Pro-tobacco advertisement exposure among African American smokers: An ecological momentary assessment study.

Science.gov (United States)

Robinson, Cendrine D; Muench, Christine; Brede, Emily; Endrighi, Romano; Szeto, Edwin H; Sells, Joanna R; Lammers, John P; Okuyemi, Kolawole S; Izmirlian, Grant; Waters, Andrew J

2018-08-01

Many African Americans live in communities with a disproportionately high density of tobacco advertisements compared to Whites. Some research indicates that point-of-sale advertising is associated with impulse purchases of cigarettes and smoking. Ecological Momentary Assessment (EMA) can be used to examine associations between tobacco advertisement exposure and smoking variables in the natural environment. Non-treatment seeking African American smokers were given a mobile device for 2weeks (N=56). They were prompted four times per day and responded to questions about recent exposure to tobacco advertisements. Participants were also asked to indicate the number of cigarettes smoked, and if they made any purchase, or an impulse purchase, since the last assessment. Linear mixed models (LMMs) analyzed between- and within-subject associations between exposure and outcomes. Participants reported seeing at least one advertisement on 33% of assessments. Of those assessments, they reported seeing menthol advertisements on 87% of assessments. Between-subject analyses revealed that participants who on average saw more advertisements were generally more likely to report purchasing cigarettes and to purchase cigarettes on impulse. Within-subject analyses revealed that when an individual participant reported seeing more advertisements than usual they were more likely to have reported purchasing cigarettes, making an impulse purchase and smoking more cigarettes during the same period, but not the subsequent time period. Many African American smokers are frequently exposed to pro-tobacco marketing. Advertisement exposure is cross-sectionally associated with impulse purchases and smoking. Future research should assess prospective associations in more detail. Published by Elsevier Ltd.

Standardizing measurement, sampling and reporting for public exposure assessments

Energy Technology Data Exchange (ETDEWEB)

Rochedo, Elaine R.R. [Instituto de Radioprotecao e Dosimetria, Comissao Nacional de Energia Nuclear, Av. Salvador Allende s/No. CEP 22780-160 Rio de Janeiro, RJ (Brazil)], E-mail: elaine@ird.gov.br

2008-11-15

UNSCEAR assesses worldwide public exposure from natural and man-made sources of ionizing radiation based on information submitted to UNSCEAR by United Nations Member States and from peer reviewed scientific literature. These assessments are used as a basis for radiation protection programs of international and national regulatory and research organizations. Although UNSCEAR describes its assessment methodologies, the data are based on various monitoring approaches. In order to reduce uncertainties and improve confidence in public exposure assessments, it would be necessary to harmonize the methodologies used for sampling, measuring and reporting of environmental results.

An Agent-Based Modeling Framework for Simulating Human Exposure to Environmental Stresses in Urban Areas

Directory of Open Access Journals (Sweden)

Liang Emlyn Yang

2018-04-01

Full Text Available Several approaches have been used to assess potential human exposure to environmental stresses and achieve optimal results under various conditions, such as for example, for different scales, groups of people, or points in time. A thorough literature review in this paper identifies the research gap regarding modeling approaches for assessing human exposure to environment stressors, and it indicates that microsimulation tools are becoming increasingly important in human exposure assessments of urban environments, in which each person is simulated individually and continuously. The paper further describes an agent-based model (ABM framework that can dynamically simulate human exposure levels, along with their daily activities, in urban areas that are characterized by environmental stresses such as air pollution and heat stress. Within the framework, decision-making processes can be included for each individual based on rule-based behavior in order to achieve goals under changing environmental conditions. The ideas described in this paper are implemented in a free and open source NetLogo platform. A basic modeling scenario of the ABM framework in Hamburg, Germany, demonstrates its utility in various urban environments and individual activity patterns, as well as its portability to other models, programs, and frameworks. The prototype model can potentially be extended to support environmental incidence management through exploring the daily routines of different groups of citizens, and comparing the effectiveness of different strategies. Further research is needed to fully develop an operational version of the model.

A structured observational method to assess dermal exposure to manufactured nanoparticles: DREAM as an initial assessment tool

NARCIS (Netherlands)

Duuren-Stuurman, B. van; Pelzer, J.; Moehlmann, C.; Berges, M.; Bard, D.; Wake, D.; Mark, D.; Jankowska, E.; Brouwer, D.

2010-01-01

Preliminary results of inventories of exposure scenarios for nanomaterials have indicated possible dermal exposure. Within the NANOSH project focused on occupational safety and health aspects of nanotechnology a shortened version of the observational DeRmal Exposure AssessMent (DREAM) method was

A quantitative screening-level approach to incorporate chemical exposure and risk into alternative assessment evaluations.

Science.gov (United States)

Arnold, Scott M; Greggs, Bill; Goyak, Katy O; Landenberger, Bryce D; Mason, Ann M; Howard, Brett; Zaleski, Rosemary T

2017-11-01

As the general public and retailers ask for disclosure of chemical ingredients in the marketplace, a number of hazard screening tools were developed to evaluate the so-called "greenness" of individual chemical ingredients and/or formulations. The majority of these tools focus only on hazard, often using chemical lists, ignoring the other part of the risk equation: exposure. Using a hazard-only focus can result in regrettable substitutions, changing 1 chemical ingredient for another that turns out to be more hazardous or shifts the toxicity burden to others. To minimize the incidents of regrettable substitutions, BizNGO describes "Common Principles" to frame a process for informed substitution. Two of these 6 principles are: "reduce hazard" and "minimize exposure." A number of frameworks have emerged to evaluate and assess alternatives. One framework developed by leading experts under the auspices of the US National Academy of Sciences recommended that hazard and exposure be specifically addressed in the same step when assessing candidate alternatives. For the alternative assessment community, this article serves as an informational resource for considering exposure in an alternatives assessment using elements of problem formulation; product identity, use, and composition; hazard analysis; exposure analysis; and risk characterization. These conceptual elements build on practices from government, academia, and industry and are exemplified through 2 hypothetical case studies demonstrating the questions asked and decisions faced in new product development. These 2 case studies-inhalation exposure to a generic paint product and environmental exposure to a shampoo rinsed down the drain-demonstrate the criteria, considerations, and methods required to combine exposure models addressing human health and environmental impacts to provide a screening level hazard and exposure (risk) analysis. This article informs practices for these elements within a comparative risk context

Simulation of Population-Based Commuter Exposure to NO2 Using Different Air Pollution Models

Directory of Open Access Journals (Sweden)

Martina S. Ragettli

2014-05-01

Full Text Available We simulated commuter routes and long-term exposure to traffic-related air pollution during commute in a representative population sample in Basel (Switzerland, and evaluated three air pollution models with different spatial resolution for estimating commute exposures to nitrogen dioxide (NO2 as a marker of long-term exposure to traffic-related air pollution. Our approach includes spatially and temporally resolved data on actual commuter routes, travel modes and three air pollution models. Annual mean NO2 commuter exposures were similar between models. However, we found more within-city and within-subject variability in annual mean (±SD NO2 commuter exposure with a high resolution dispersion model (40 ± 7 µg m−3, range: 21–61 than with a dispersion model with a lower resolution (39 ± 5 µg m−3; range: 24–51, and a land use regression model (41 ± 5 µg m−3; range: 24–54. Highest median cumulative exposures were calculated along motorized transport and bicycle routes, and the lowest for walking. For estimating commuter exposure within a city and being interested also in small-scale variability between roads, a model with a high resolution is recommended. For larger scale epidemiological health assessment studies, models with a coarser spatial resolution are likely sufficient, especially when study areas include suburban and rural areas.

Task-based exposure assessment of nanoparticles in the workplace

International Nuclear Information System (INIS)

Ham, Seunghon; Yoon, Chungsik; Lee, Euiseung; Lee, Kiyoung; Park, Donguk; Chung, Eunkyo; Kim, Pilje; Lee, Byoungcheun

2012-01-01

Although task-based sampling is, theoretically, a plausible approach to the assessment of nanoparticle exposure, few studies using this type of sampling have been published. This study characterized and compared task-based nanoparticle exposure profiles for engineered nanoparticle manufacturing workplaces (ENMW) and workplaces that generated welding fumes containing incidental nanoparticles. Two ENMW and two welding workplaces were selected for exposure assessments. Real-time devices were utilized to characterize the concentration profiles and size distributions of airborne nanoparticles. Filter-based sampling was performed to measure time-weighted average (TWA) concentrations, and off-line analysis was performed using an electron microscope. Workplace tasks were recorded by researchers to determine the concentration profiles associated with particular tasks/events. This study demonstrated that exposure profiles differ greatly in terms of concentrations and size distributions according to the task performed. The size distributions recorded during tasks were different from both those recorded during periods with no activity and from the background. The airborne concentration profiles of the nanoparticles varied according to not only the type of workplace but also the concentration metrics. The concentrations measured by surface area and the number concentrations measured by condensation particle counter, particulate matter 1.0, and TWA mass concentrations all showed a similar pattern, whereas the number concentrations measured by scanning mobility particle sizer indicated that the welding fume concentrations at one of the welding workplaces were unexpectedly higher than were those at workplaces that were engineering nanoparticles. This study suggests that a task-based exposure assessment can provide useful information regarding the exposure profiles of nanoparticles and can therefore be used as an exposure assessment tool.

Pathway analysis and exposure assessment: MEPAS modeling for nonradiological chemical contaminants at the Hanford Site

International Nuclear Information System (INIS)

Blanton, M.L.; Dirkes, R.; Buck, J.; Cooper, A.; Castieton, K.; Glantz, C.

1995-01-01

A Chemical Pathway Analysis and Exposure Assessment was performed by the Surface Environmental Surveillance Project (SESP). The SESP monitors air, surface water, sediment, agricultural products, vegetation, soil, and wildlife in order to assess onsite of offsite environmental impacts and offsite human health risk at the Hanford Site. The objectives of this study are (1) determine if a nonradiological chemical monitoring program is warranted for the Hanford Site, (2) ensure that the selection of surveillance parameters such as media, sampling location, and analytes are chosen in a manner that is scientifically sound and cost-efficient, and (3) identify specific nonradiological chemicals of concern (COC) for the Hanford Site. The basis for identification of COC for the Hanford Site was an extensive literature review. The model was also used to predict COC concentrations required onsite to achieve an offsite cancer incidence of 1 E-6 and a hazard quotient of 1.0. This study indicated that nonradiological chemical contamination occurring onsite does not pose a significant offsite human health risk. The highest cancer incidence to the offsite maximally exposed individual from COC was from arsenic (1.76E-1 0); the highest hazard quotient was chromium VI (1.48E-04)

How much, how long, what, and where: air pollution exposure assessment for epidemiologic studies of respiratory disease.

Science.gov (United States)

Brauer, Michael

2010-05-01

Epidemiology has played an important role in the understanding of air pollution as a risk factor for respiratory disease and in the evidence base for air quality standards. With the widespread availability of genetic information and increasingly sophisticated measurements of molecular markers of adverse effects, there is a need for more specific and precise assessment of exposure to maximize the potential information to be derived from epidemiologic studies. Here advances in air pollution exposure assessment and their applications to studies of respiratory disease are reviewed, with a focus on recent studies of traffic-related air pollution and asthma. Although continuous measurements of personal exposures for all study subjects for a complete study period might be considered the desired "gold standard" for exposure, this is rarely, if ever, achieved due to feasibility constraints. Given this, exposure is typically estimated using models. Recent applications of geospatial (e.g., land use regression) models to studies of respiratory disease have made possible new study designs focused on spatial variability in exposure within urban areas and have provided new insights into the potential role of traffic-related air pollution (TRAP) as a risk factor for the development of childhood asthma. Substantial uncertainty remains, however, regarding what agent(s) within TRAP might be responsible for the observed associations. Future research will require increasing the specificity of exposure assessment to identify the potential roles of individual air pollution components, to elucidate potential mechanisms, and to facilitate studies of mixtures and gene-air pollution interactions.

Exposure levels, environmental fate modelling and human health risk assessment of lindane in Ghana

International Nuclear Information System (INIS)

Adu-Kumi, S.

2011-01-01

This thesis discusses an innovative approach of combining chemical trace analysis including the use of 13 C-labelled isotopes as internal and recovery standards) with multi-media modelling for assessing health risks of Lindane which is a persistent organic pollutant (POP) and a commercial formulated insecticide also known as Gamma-hexachlorocyclohexane (γ-HCH). Samples studied were background air, human breast milk, and edible fish (tilapia and catfish). The investigations focused on the exposure of the general population. For the first time levels and seasonal variation of Lindane, α-HCH and β-HCH in background air of Lake Bosumtwi, Kwabenya and East Legon in Ghana were studied with polyurethane foam based passive air samplers. Lindane (average concentration 53 pg m -3 ) was measured in all samples with (i) gas chromatography-mass spectrometer (GC-MS) and (ii) gas chromatography-mass spectrometer operated in electron ionization mode (GC-EI-MS). Agricultural application and revolatilisation from soils were main primary and secondary sources of HCH releases. Levels and variation of Lindane, α-HCH and β-HCH in pooled and individual human breast milk samples collected from lactating mothers countrywide were determined using a high-resolution gas chromatography interfaced with a high-resolution gas chromatography interfaced with a high-resolution mass spectrometer (HRGC-HRMS). This constitutes the first comprehensive nationwide human breast milk study of assessing risks of HCHs for the general population of Ghana. Mothers were selected from three major cities (Accra, Kumasi and Tamale) and three rural communities (Ada, Jachie/Pramso and Tolon) representing the Southern, Middle and Northern sectors respectively. The results of the study showed that the general population of Ghana is widely exposed to HCHs although the current levels are generally low; and also suggest that the usage pattern and exposure levels of Lindane vary among the various regions in Ghana. �

A Conceptual Framework for the Assessment of Cumulative Exposure to Air Pollution at a Fine Spatial Scale

Directory of Open Access Journals (Sweden)

Kihal-Talantikite Wahida

2016-03-01

Full Text Available Many epidemiological studies examining long-term health effects of exposure to air pollutants have characterized exposure by the outdoor air concentrations at sites that may be distant to subjects’ residences at different points in time. The temporal and spatial mobility of subjects and the spatial scale of exposure assessment could thus lead to misclassification in the cumulative exposure estimation. This paper attempts to fill the gap regarding cumulative exposure assessment to air pollution at a fine spatial scale in epidemiological studies investigating long-term health effects. We propose a conceptual framework showing how major difficulties in cumulative long-term exposure assessment could be surmounted. We then illustrate this conceptual model on the case of exposure to NO2 following two steps: (i retrospective reconstitution of NO2 concentrations at a fine spatial scale; and (ii a novel approach to assigning the time-relevant exposure estimates at the census block level, using all available data on residential mobility throughout a 10- to 20-year period prior to that for which the health events are to be detected. Our conceptual framework is both flexible and convenient for the needs of different epidemiological study designs.

A Conceptual Framework for the Assessment of Cumulative Exposure to Air Pollution at a Fine Spatial Scale

Science.gov (United States)

Wahida, Kihal-Talantikite; Padilla, Cindy M.; Denis, Zmirou-Navier; Olivier, Blanchard; Géraldine, Le Nir; Philippe, Quenel; Séverine, Deguen

2016-01-01

Many epidemiological studies examining long-term health effects of exposure to air pollutants have characterized exposure by the outdoor air concentrations at sites that may be distant to subjects’ residences at different points in time. The temporal and spatial mobility of subjects and the spatial scale of exposure assessment could thus lead to misclassification in the cumulative exposure estimation. This paper attempts to fill the gap regarding cumulative exposure assessment to air pollution at a fine spatial scale in epidemiological studies investigating long-term health effects. We propose a conceptual framework showing how major difficulties in cumulative long-term exposure assessment could be surmounted. We then illustrate this conceptual model on the case of exposure to NO2 following two steps: (i) retrospective reconstitution of NO2 concentrations at a fine spatial scale; and (ii) a novel approach to assigning the time-relevant exposure estimates at the census block level, using all available data on residential mobility throughout a 10- to 20-year period prior to that for which the health events are to be detected. Our conceptual framework is both flexible and convenient for the needs of different epidemiological study designs. PMID:26999170

What are the elements required to improve exposure estimates in life cycle assessments?

DEFF Research Database (Denmark)

Ernstoff, Alexi; Rosenbaum, Ralph K.; Margni, Manuele

2016-01-01

human toxicity and ecosystem toxicity of chemicals posed by different product life cycle stages are characterized in the life cycle impact assessment (LCIA) phase. Exposure and effect quantification as part of LCIA toxicity characterization faces numerous challenges related to inventory analysis (e.......g. number and quantity of chemicals emitted), substance-specific modelling (e.g. organics, inorganics, nano-materials) in various environments and time horizons, human and ecosystem exposure quantification (e.g. exposed organisms and exposure pathways), and toxicity end-points (e.g. carcinogenicity...... chemical exposure and harmful effects. Thereby, we structure this study of key elements identified as areas of elevated public, industrial, regulatory, and scientific concerns. We found the majority of missing elements are directly related to the definition of exposed populations (both ecosystems...

Assessment of Industrial Exposure to Magnetic Fields (invited paper)

International Nuclear Information System (INIS)

Chadwick, P.

1999-01-01

Magnetic field strengths produced by industrial processes can be very large, but they often exhibit a marked spatial variation. Whilst there may be the potential for exposures of workers to be high, actual exposure will be determined to a great extent by working practices. Possible metrics for epidemiological studies might be based on the temporal variability of exposure as well as maximum operator exposure or time-weighted average exposure and, whilst it might be possible to estimate these quantities from spot magnetic field strength measurements and observed working practices, this might be very difficult to achieve in practice. An alternative would be the use of a logging dosemeter: this paper describes some of the results of exposure assessments carried out in industrial environments with a modified EMDEX II magnetic field dosemeter. Magnetic fields in industrial environments often have waveforms which are not purely sinusoidal. Distortion can be introduced by the magnetic saturation of transformer and motor cores, by rectification, by poor matching between oscillator circuits and loads and when thyristors are used to control power. The resulting repetitive but non-sinusoidal magnetic field waveforms can be recorded and analysed; the spectral data may be incorporated into possible exposure metrics. It is also important to ensure that measurement instrumentation is responding appropriately in a non-sinusoidal field and this can only be done if the spectral content of the field is characterised fully. Some non-sinusoidal magnetic field waveforms cannot be expressed as a harmonic series. Specialist instrumentation and techniques are needed to assess exposure to such fields. Examples of approaches to the assessment of exposure to repetitive and non-repetitive magnetic fields are also discussed. (author)

Potential for MERLIN-Expo, an advanced tool for higher tier exposure assessment, within the EU chemical legislative frameworks

International Nuclear Information System (INIS)

Suciu, Nicoleta; Tediosi, Alice; Ciffroy, Philippe; Altenpohl, Annette; Brochot, Céline; Verdonck, Frederik; Ferrari, Federico; Giubilato, Elisa; Capri, Ettore; Fait, Gabriella

2016-01-01

MERLIN-Expo merges and integrates advanced exposure assessment methodologies, allowing the building of complex scenarios involving several pollution sources and targets. The assessment of exposure and risks to human health from chemicals is of major concern for policy and ultimately benefits all citizens. The development and operational fusion of the advanced exposure assessment methodologies envisaged in the MERLIN-Expo tool will have a significant impact in the long term on several policies dealing with chemical safety management. There are more than 30 agencies in Europe related to exposure and risk evaluation of chemicals, which have an important role in implementing EU policies, having especially tasks of technical, scientific, operational and/or regulatory nature. The main purpose of the present paper is to introduce MERLIN-Expo and to highlight its potential for being effectively integrated within the group of tools available to assess the risk and exposure of chemicals for EU policy. The main results show that the tool is highly suitable for use in site-specific or local impact assessment, with minor modifications it can also be used for Plant Protection Products (PPPs), biocides and REACH, while major additions would be required for a comprehensive application in the field of consumer and worker exposure assessment. - Highlights: • Exposure and risk evaluation of chemicals • Coupling environmental exposure and pharmacokinetic models • MERLIN-expo as a higher tier exposure tool • MERLIN-expo potential application in EU chemical regulations • EU legislations and policies related to risk assessment and management of chemicals

Potential for MERLIN-Expo, an advanced tool for higher tier exposure assessment, within the EU chemical legislative frameworks

Energy Technology Data Exchange (ETDEWEB)

Suciu, Nicoleta, E-mail: nicoleta.suciu@unicatt.it [Università Cattolica del Sacro Cuore, 29122 Piacenza (Italy); Tediosi, Alice [Aeiforia Srl, 29027 Gariga di Podenzano (PC) (Italy); Ciffroy, Philippe [Electricité de France (EDF) R& D, National Hydraulic and Environment Laboratory, 6 quai Watier, 78400 Chatou (France); Altenpohl, Annette [Österreichisches Normungsinstitut/Austrian Standards Institute, Heinestraße 38, 1020 Wien (Austria); Brochot, Céline [INERIS, Parc ALATA, BP2, 60550 Verneuil en Halatte (France); Verdonck, Frederik [ARCHE cvba, Liefkensstraat 35d, 9032 Gent-Wondelgem (Belgium); Ferrari, Federico [Aeiforia Srl, 29027 Gariga di Podenzano (PC) (Italy); Giubilato, Elisa [University Ca Foscari Venice, Department of Environmental Sciences, Informatics and Statistics, via Torino 155, 30172 Mestre-Venice (Italy); Capri, Ettore [Università Cattolica del Sacro Cuore, 29122 Piacenza (Italy); Fait, Gabriella [EFSA, via Carlo Magno 1/a, 43126 Parma (Italy)

2016-08-15

MERLIN-Expo merges and integrates advanced exposure assessment methodologies, allowing the building of complex scenarios involving several pollution sources and targets. The assessment of exposure and risks to human health from chemicals is of major concern for policy and ultimately benefits all citizens. The development and operational fusion of the advanced exposure assessment methodologies envisaged in the MERLIN-Expo tool will have a significant impact in the long term on several policies dealing with chemical safety management. There are more than 30 agencies in Europe related to exposure and risk evaluation of chemicals, which have an important role in implementing EU policies, having especially tasks of technical, scientific, operational and/or regulatory nature. The main purpose of the present paper is to introduce MERLIN-Expo and to highlight its potential for being effectively integrated within the group of tools available to assess the risk and exposure of chemicals for EU policy. The main results show that the tool is highly suitable for use in site-specific or local impact assessment, with minor modifications it can also be used for Plant Protection Products (PPPs), biocides and REACH, while major additions would be required for a comprehensive application in the field of consumer and worker exposure assessment. - Highlights: • Exposure and risk evaluation of chemicals • Coupling environmental exposure and pharmacokinetic models • MERLIN-expo as a higher tier exposure tool • MERLIN-expo potential application in EU chemical regulations • EU legislations and policies related to risk assessment and management of chemicals.

Instruments to assess and measure personal and environmental radiofrequency-electromagnetic field exposures.

Science.gov (United States)

Bhatt, Chhavi Raj; Redmayne, Mary; Abramson, Michael J; Benke, Geza

2016-03-01

Radiofrequency-electromagnetic field (RF-EMF) exposure of human populations is increasing due to the widespread use of mobile phones and other telecommunication and broadcasting technologies. There are ongoing concerns about potential short- and long-term public health consequences from RF-EMF exposures. To elucidate the RF-EMF exposure-effect relationships, an objective evaluation of the exposures with robust assessment tools is necessary. This review discusses and compares currently available RF-EMF exposure assessment instruments, which can be used in human epidemiological studies. Quantitative assessment instruments are either mobile phone-based (apps/software-modified and hardware-modified) or exposimeters. Each of these tool has its usefulness and limitations. Our review suggests that assessment of RF-EMF exposures can be improved by using these tools compared to the proxy measures of exposure (e.g. questionnaires and billing records). This in turn, could be used to help increase knowledge about RF-EMF exposure induced health effects in human populations.

Instruments to assess and measure personal and environmental radiofrequency-electromagnetic field exposures

International Nuclear Information System (INIS)

Bhatt, Chhavi R.; Redmayne, Mary; Abramson, Michael J.; Benke, Geza

2016-01-01

Radiofrequency-electromagnetic field (RF-EMF) exposure of human populations is increasing due to the widespread use of mobile phones and other telecommunication and broadcasting technologies. There are ongoing concerns about potential short- and long-term public health consequences from RF-EMF exposures. To elucidate the RF-EMF exposure-effect relationships, an objective evaluation of the exposures with robust assessment tools is necessary. This review discusses and compares currently available RF-EMF exposure assessment instruments, which can be used in human epidemiological studies. Quantitative assessment instruments are either mobile phone-based (apps/software-modified and hardware-modified) or exposimeters. Each of these tool has its usefulness and limitations. Our review suggests that assessment of RF-EMF exposures can be improved by using these tools compared to the proxy measures of exposure (e.g. questionnaires and billing records). This in turn, could be used to help increase knowledge about RF-EMF exposure induced health effects in human populations.

Modeled occupational exposures to gas-phase medical laser-generated air contaminants.

Science.gov (United States)

Lippert, Julia F; Lacey, Steven E; Jones, Rachael M

2014-01-01

Exposure monitoring data indicate the potential for substantive exposure to laser-generated air contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported gas-phase constituents of medical laser-generated air contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) concentrations in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The concentrations were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.

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...

Retrospective internal radiation exposure assessment in occupational epidemiology

International Nuclear Information System (INIS)

Neton, J.W.; Flora, J.T.; Spitz, H.B.; Taulbee, T.D.

2000-01-01

Epidemiologic studies of workers at U.S. Department of Energy facilities are being conducted by the U.S. National Institute for Occupational Safety and Health to evaluate the health risk associated with exposure to sources of external and internal ionizing radiation. While exposure to external sources of radiation can be estimated from personal dosimeter data, reconstruction of exposure due to internally deposited radioactivity is more challenging because bioassay monitoring data is frequently less complete. Although comprehensive monitoring was provided for workers with the highest internal exposures, the majority of workers were monitored relatively infrequently. This monitoring was conducted to demonstrate compliance with regulations rather than to evaluate exposure for use in epidemiologic studies. Attributes of past internal monitoring programs that challenge accurate exposure assessment include: incomplete characterization of the workplace source term; a lack of timely measurements; insensitive and/or nonspecific bioassay measurements; and the presence of censored data. In spite of these limitations, many facilities have collected a large amount of worker and workplace monitoring information that can be used to evaluate internal exposure while minimizing worker misclassification. This paper describes a systematic approach for using the available worker and workplace monitoring data that can lead to either a qualitative or quantitative retrospective assessment of internal exposures. Various aspects of data analysis will be presented, including the evaluation of minimum detectable dose, the treatment of censored data, and the use of combinations of bioassay and workplace data to characterize exposures. Examples of these techniques applied to a cohort study involving chronic exposure scenarios to uranium are provided. A strategy for expressing exposure or dose in fundamental, unweighted units related to the quantity of radiation delivered to an organ will also

Assessment of health risks from exposure to ionizing radiation

International Nuclear Information System (INIS)

Beebe, G.W.

1982-01-01

Rapid development in the assessment of health risks from exposure to ionizing radiation has produced an impressive array of risk differentials of presumed biologic significance. In the human data these differentials involve: (1) the variety of cancer, especially its size; (2) host factors, especially age; (3) time following exposure; (4) magnitude of dose; and (5) type of radiation. From experimental work we may presume that dose-rate also plays a role, especially for sparsely ionizing radiation. Current research is extending the scope of differentials with respect to these and other variables, including cell type and concomitant environmental risk factors, and testing dose-response models suggested by experimental and theoretical work. As facts to be explained, differentials in risk may lead to hypotheses to be explored experimentally and improve our understanding of how ionizing radiation causes cancer. 74 references

Human exposure assessment: Approaches for chemicals (REACH) and biocides (BPD)

NARCIS (Netherlands)

Hemmen, J.J. van; Gerritsen-Ebben, R.

2008-01-01

The approaches that are indicated in the various guidance documents for the assessment of human exposure for chemicals and biocides are summarised. This reflects the TNsG (Technical notes for Guidance) version 2: human exposure assessment for biocidal products (1) under the BPD (Biocidal Products

Extending Participatory Sensing to Personal Exposure Using Microscopic Land Use Regression Models

Directory of Open Access Journals (Sweden)

Luc Dekoninck

2017-05-01

Full Text Available Personal exposure is sensitive to the personal features and behavior of the individual, and including interpersonal variability will improve the health and quality of life evaluations. Participatory sensing assesses the spatial and temporal variability of environmental indicators and is used to quantify this interpersonal variability. Transferring the participatory sensing information to a specific study population is a basic requirement for epidemiological studies in the near future. We propose a methodology to reduce the void between participatory sensing and health research. Instantaneous microscopic land-use regression modeling (µLUR is an innovative approach. Data science techniques extract the activity-specific and route-sensitive spatiotemporal variability from the data. A data workflow to prepare and apply µLUR models to any mobile population is presented. The µLUR technique and data workflow are illustrated with models for exposure to traffic related Black Carbon. The example µLURs are available for three micro-environments; bicycle, in-vehicle, and indoor. Instantaneous noise assessments supply instantaneous traffic information to the µLURs. The activity specific models are combined into an instantaneous personal exposure model for Black Carbon. An independent external validation reached a correlation of 0.65. The µLURs can be applied to simulated behavioral patterns of individuals in epidemiological cohorts for advanced health and policy research.

GPS-based Microenvironment Tracker (MicroTrac) Model to Estimate Time-Location of Individuals for Air Pollution Exposure Assessments: Model Evaluation in Central North Carolina

Science.gov (United States)

A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure...

Atmospheric Dispersion Modelling and Spatial Analysis to Evaluate Population Exposure to Pesticides from Farming Processes

Directory of Open Access Journals (Sweden)

Sofia Costanzini

2018-01-01

Full Text Available This work originates from an epidemiological study aimed to assess the correlation between population exposure to pesticides used in agriculture and adverse health effects. In support of the population exposure evaluation two models implemented by the authors were applied: a GIS-based proximity model and the CAREA atmospheric dispersion model. In this work, the results of the two models are presented and compared. Despite the proximity analysis is widely used for these kinds of studies, it was investigated how meteorology could affect the exposure assessment. Both models were applied to pesticides emitted by 1519 agricultural fields and considering 2584 receptors distributed over an area of 8430 km2. CAREA output shows a considerable enhancement in the percentage of exposed receptors, from the 4% of the proximity model to the 54% of the CAREA model. Moreover, the spatial analysis of the results on a specific test site showed that the effects of meteorology considered by CAREA led to an anisotropic exposure distribution that differs considerably from the symmetric distribution resulting by the proximity model. In addition, the results of a field campaign for the definition and planning of ground measurement of concentration for the validation of CAREA are presented. The preliminary results showed how, during treatments, pesticide concentrations distant from the fields are significantly higher than background values.

Assessment of occupational exposure to radiofrequency fields and radiation

International Nuclear Information System (INIS)

Cooper, T. G.; Allen, S. G.; Blackwell, R. P.; Litchfield, I.; Mann, S. M.; Pope, J. M.; Van Tongeren, M. J. A.

2004-01-01

The use of personal monitors for the assessment of exposure to radiofrequency fields and radiation in potential future epidemiological studies of occupationally exposed populations has been investigated. Data loggers have been developed for use with a commercially available personal monitor and these allowed personal exposure records consisting of time-tagged measurements of electric and magnetic field strength to be accrued over extended periods of the working day. The instrumentation was worn by workers carrying out tasks representative of some of their typical daily activities at a variety of radio sites. The results indicated significant differences in the exposures of workers in various RF environments. A number of measures of exposure have been examined with a view to assessing possible exposure metrics for epidemiological studies. There was generally a good correlation between a given measure of electric field strength and the same measure of magnetic field strength. (authors)

Categorization framework to aid exposure assessment of nanomaterials in consumer products

DEFF Research Database (Denmark)

Hansen, Steffen Foss; Michelson, Evan S.; Kamper, Anja

2008-01-01

Exposure assessment is crucial for risk assessment for nanomaterials. We propose a framework to aid exposure assessment in consumer products. We determined the location of the nanomaterials and the chemical identify of the 580 products listed in the inventory maintained by the Woodrow Wilson Inte...

Environmental tobacco smoke in designated smoking areas in the hospitality industry: exposure measurements, exposure modelling and policy assessment.

Science.gov (United States)

McNabola, A; Eyre, G J; Gill, L W

2012-09-01

Tobacco control policy has been enacted in many jurisdictions worldwide banning smoking in the workplace. In the hospitality sector many businesses such as bars, hotels and restaurants have installed designated smoking areas on their premises and allowance for such smoking areas has been made in the tobacco control legislation of many countries. An investigation was carried out into the level of exposure to environmental tobacco smoke (ETS) present in 8 pubs in Ireland which included designated smoking areas complying with two different definitions of a smoking area set out in Irish legislation. In addition, ETS exposure in a pub with a designated smoking area not in compliance with the legislation was also investigated. The results of this investigation showed that the two differing definitions of a smoking area present in pubs produced similar concentrations of benzene within smoking areas (5.1-5.4 μg/m(3)) but differing concentrations within the 'smoke-free' areas (1.42-3.01 μg/m(3)). Smoking areas in breach of legislative definitions were found to produce the highest levels of benzene in the smoking area (49.5 μg/m(3)) and 'smoke-free' area (7.68 μg/m(3)). 3D exposure modelling of hypothetical smoking areas showed that a wide range of ETS exposure concentrations were possible in smoking areas with the same floor area and same smoking rate but differing height to width and length to width ratios. The results of this investigation demonstrate that significant scope for improvement of ETS exposure concentrations in pubs and in smoking areas may exist by refining and improving the legislative definitions of smoking areas in law. Copyright © 2012 Elsevier Ltd. All rights reserved.

Health Risk Assessment of Inhalation Exposure to Formaldehyde and Benzene in Newly Remodeled Buildings, Beijing

Science.gov (United States)

Huang, Lihui; Mo, Jinhan; Sundell, Jan; Fan, Zhihua; Zhang, Yinping

2013-01-01

Objective To assess health risks associated with inhalation exposure to formaldehyde and benzene mainly emitted from building and decoration materials in newly remodeled indoor spaces in Beijing. Methods We tested the formaldehyde and benzene concentrations in indoor air of 410 dwellings and 451 offices remodeled within the past year, in which the occupants had health concerns about indoor air quality. To assess non-carcinogenic health risks, we compared the data to the health guidelines in China and USA, respectively. To assess carcinogenic health risks, we first modeled indoor personal exposure to formaldehyde and benzene using the concentration data, and then estimated the associated cancer risks by multiplying the indoor personal exposure by the Inhalation Unit Risk values (IURs) provided by the U.S. EPA Integrated Risk Information System (U.S. EPA IRIS) and the California Office of Environmental Health Hazard Assessment (OEHHA), respectively. Results (1) The indoor formaldehyde concentrations of 85% dwellings and 67% offices were above the acute Reference Exposure Level (REL) recommended by the OEHHA and the concentrations of all tested buildings were above the chronic REL recommended by the OEHHA; (2) The indoor benzene concentrations of 12% dwellings and 32% offices exceeded the reference concentration (RfC) recommended by the U.S. EPA IRIS; (3) The median cancer risks from indoor exposure to formaldehyde and benzene were 1,150 and 106 per million (based on U.S. EPA IRIS IURs), 531 and 394 per million (based on OEHHA IURs). Conclusions In the tested buildings, formaldehyde exposure may pose acute and chronic non-carcinogenic health risks to the occupants, whereas benzene exposure may pose chronic non-carcinogenic risks to the occupants. Exposure to both compounds is associated with significant carcinogenic risks. Improvement in ventilation, establishment of volatile organic compounds (VOCs) emission labeling systems for decorating and refurbishing materials

Occupational exposure assessment: Practices in Malaysian nuclear agency

Energy Technology Data Exchange (ETDEWEB)

Sarowi, S. Muhd, E-mail: suzie@nuclearmalaysia.gov.my; Ramli, S. A.; Kontol, K. Mohamad [Radiation Safety & Health Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia); Rahman, N. A. H. Abd. [Faculty of Science & Mathematics, Sultan Idris of Education Universit, 35900, Tanjong Malim, Perak Darul Ridzuan (Malaysia)

2016-01-22

Malaysian Nuclear Agency (Nuclear Malaysia) is the leading agency in introducing and promoting the application of nuclear science technology in Malaysia. The agency provides major nuclear facilities purposely for research and commercialisation such as reactor, irradiation plants and radioisotope production laboratory. When dealing with ionizing radiation, there is an obligatory requirement to monitor and assess the radiation exposure to the workers. The personal dose of radiation workers were monitored monthly by assessing their Thermoluminescence Dosimeter (TLD) dose reading. This paper will discuss the current practice in managing, assessing, record keeping and reporting of the occupational exposure in Nuclear Malaysia including the Health Physic Group roles and challenges. The statistics on occupational radiation exposure of monitored workers working in different fields in Nuclear Malaysia from 2011 - 2013 will also be presented. The results show that the null hypothesis (H{sub 0}) was accepted which the means of every populations are all equal or not differ significantly. This hypothesis states that the dose exposure received by the radiation workers in Nuclear Malaysia is similar and there were no significant changes from 2011 to 2013. The radiation monitoring programme correlate with the requirement of our national law, the Atomic Energy Licensing Act 1984 (Act 304)

Occupational exposure assessment: Practices in Malaysian nuclear agency

Science.gov (United States)

Sarowi, S. Muhd; Ramli, S. A.; Kontol, K. Mohamad; Rahman, N. A. H. Abd.

2016-01-01

Malaysian Nuclear Agency (Nuclear Malaysia) is the leading agency in introducing and promoting the application of nuclear science technology in Malaysia. The agency provides major nuclear facilities purposely for research and commercialisation such as reactor, irradiation plants and radioisotope production laboratory. When dealing with ionizing radiation, there is an obligatory requirement to monitor and assess the radiation exposure to the workers. The personal dose of radiation workers were monitored monthly by assessing their Thermoluminescence Dosimeter (TLD) dose reading. This paper will discuss the current practice in managing, assessing, record keeping and reporting of the occupational exposure in Nuclear Malaysia including the Health Physic Group roles and challenges. The statistics on occupational radiation exposure of monitored workers working in different fields in Nuclear Malaysia from 2011 - 2013 will also be presented. The results show that the null hypothesis (H₀) was accepted which the means of every populations are all equal or not differ significantly. This hypothesis states that the dose exposure received by the radiation workers in Nuclear Malaysia is similar and there were no significant changes from 2011 to 2013. The radiation monitoring programme correlate with the requirement of our national law, the Atomic Energy Licensing Act 1984 (Act 304).

Occupational exposure assessment: Practices in Malaysian nuclear agency

International Nuclear Information System (INIS)

Sarowi, S. Muhd; Ramli, S. A.; Kontol, K. Mohamad; Rahman, N. A. H. Abd.

2016-01-01

Malaysian Nuclear Agency (Nuclear Malaysia) is the leading agency in introducing and promoting the application of nuclear science technology in Malaysia. The agency provides major nuclear facilities purposely for research and commercialisation such as reactor, irradiation plants and radioisotope production laboratory. When dealing with ionizing radiation, there is an obligatory requirement to monitor and assess the radiation exposure to the workers. The personal dose of radiation workers were monitored monthly by assessing their Thermoluminescence Dosimeter (TLD) dose reading. This paper will discuss the current practice in managing, assessing, record keeping and reporting of the occupational exposure in Nuclear Malaysia including the Health Physic Group roles and challenges. The statistics on occupational radiation exposure of monitored workers working in different fields in Nuclear Malaysia from 2011 - 2013 will also be presented. The results show that the null hypothesis (H 0 ) was accepted which the means of every populations are all equal or not differ significantly. This hypothesis states that the dose exposure received by the radiation workers in Nuclear Malaysia is similar and there were no significant changes from 2011 to 2013. The radiation monitoring programme correlate with the requirement of our national law, the Atomic Energy Licensing Act 1984 (Act 304)

Exposure Monitoring and Risk Assessment of Biphenyl in the Workplace

OpenAIRE

Kim, Hyeon-Yeong; Shin, Sae-Mi; Ham, Miran; Lim, Cheol-Hong; Byeon, Sang-Hoon

2015-01-01

This study was performed to assess exposure to and the risk caused by biphenyl in the workplace. Biphenyl is widely used as a heat transfer medium and as an emulsifier and polish in industry. Vapor or high levels of dust inhalation and dermal exposure to biphenyl can cause eye inflammation, irritation of respiratory organs, and permanent lesions in the liver and nervous system. In this study, the workplace environment concentrations were assessed as central tendency exposure and reasonable ma...

Sex Differences in Adolescent Depression: Stress Exposure and Reactivity Models

Science.gov (United States)

Hankin, Benjamin L.; Mermelstein, Robin; Roesch, Linda

2007-01-01

Stress exposure and reactivity models were examined as explanations for why girls exhibit greater levels of depressive symptoms than boys. In a multiwave, longitudinal design, adolescents' depressive symptoms, alcohol usage, and occurrence of stressors were assessed at baseline, 6, and 12 months later (N=538; 54.5% female; ages 13-18, average…

Development of a physiologically based pharmacokinetic model for assessment of human exposure to bisphenol A

International Nuclear Information System (INIS)

Yang, Xiaoxia; Doerge, Daniel R.; Teeguarden, Justin G.; Fisher, Jeffrey W.

2015-01-01

A previously developed physiologically based pharmacokinetic (PBPK) model for bisphenol A (BPA) in adult rhesus monkeys was modified to characterize the pharmacokinetics of BPA and its phase II conjugates in adult humans following oral ingestion. Coupled with in vitro studies on BPA metabolism in the liver and the small intestine, the PBPK model was parameterized using oral pharmacokinetic data with deuterated-BPA (d 6 -BPA) delivered in cookies to adult humans after overnight fasting. The availability of the serum concentration time course of unconjugated d 6 -BPA offered direct empirical evidence for the calibration of BPA model parameters. The recalibrated PBPK adult human model for BPA was then evaluated against published human pharmacokinetic studies with BPA. A hypothesis of decreased oral uptake was needed to account for the reduced peak levels observed in adult humans, where d 6 -BPA was delivered in soup and food was provided prior to BPA ingestion, suggesting the potential impact of dosing vehicles and/or fasting on BPA disposition. With the incorporation of Monte Carlo analysis, the recalibrated adult human model was used to address the inter-individual variability in the internal dose metrics of BPA for the U.S. general population. Model-predicted peak BPA serum levels were in the range of pM, with 95% of human variability falling within an order of magnitude. This recalibrated PBPK model for BPA in adult humans provides a scientific basis for assessing human exposure to BPA that can serve to minimize uncertainties incurred during extrapolations across doses and species. - Highlights: • A PBPK model predicts the kinetics of bisphenol A (BPA) in adult humans. • Serum concentrations of aglycone BPA are available for model calibration. • Model predicted peak BPA serum levels for adult humans were in the range of pM. • Model predicted 95% of human variability fell within an order of magnitude.

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...

Assessment of personal exposures to optical radiation in large entertainment venues

International Nuclear Information System (INIS)

Bonner, R.; O'Hagan, J. B.; Khazova, M.

2012-01-01

Workplace exposure to optical radiation from artificial sources is regulated in Europe under the Artificial Optical Radiation Directive 2006/25/EC implemented in the UK as The Control of Artificial Optical Radiation at Work Regulations 2010. The entertainment environment often presents an extremely complex situation for the assessment of occupational exposures. Multiple illumination sources, continuously changing illumination conditions and people moving during performances add further complexity to the assessment. This document proposes a methodology for assessing the risks arising from exposure to optical radiation and presents detailed case studies of practical assessment for two large entertainment venues. (authors)

Heavy Metal Exposure and Metabolic Syndrome: Evidence from Human and Model System Studies.

Science.gov (United States)

Planchart, Antonio; Green, Adrian; Hoyo, Cathrine; Mattingly, Carolyn J

2018-03-01

Metabolic syndrome (MS) describes the co-occurrence of conditions that increase one's risk for heart disease and other disorders such as diabetes and stroke. The worldwide increase in the prevalence of MS cannot be fully explained by lifestyle factors such as sedentary behavior and caloric intake alone. Environmental exposures, such as heavy metals, have been implicated, but results are conflicting and possible mechanisms remain unclear. To assess recent progress in determining a possible role between heavy metal exposure and MS, we reviewed epidemiological and model system data for cadmium (Cd), lead (Pb), and mercury (Hg) from the last decade. Data from 36 epidemiological studies involving 17 unique countries/regions and 13 studies leveraging model systems are included in this review. Epidemiological and model system studies support a possible association between heavy metal exposure and MS or comorbid conditions; however, results remain conflicting. Epidemiological studies were predominantly cross-sectional and collectively, they highlight a global interest in this question and reveal evidence of differential susceptibility by sex and age to heavy metal exposures. In vivo studies in rats and mice and in vitro cell-based assays provide insights into potential mechanisms of action relevant to MS including altered regulation of lipid and glucose homeostasis, adipogenesis, and oxidative stress. Heavy metal exposure may contribute to MS or comorbid conditions; however, available data are conflicting. Causal inference remains challenging as epidemiological data are largely cross-sectional; and variation in study design, including samples used for heavy metal measurements, age of subjects at which MS outcomes are measured; the scope and treatment of confounding factors; and the population demographics vary widely. Prospective studies, standardization or increased consistency across study designs and reporting, and consideration of molecular mechanisms informed by model

DynaPop-X: A population dynamics model applied to spatio-temporal exposure assessment - Implementation aspects from the CRISMA project

Science.gov (United States)

Aubrecht, Christoph; Steinnocher, Klaus; Humer, Heinrich; Huber, Hermann

2014-05-01

In the context of proactive disaster risk as well as immediate situational crisis management knowledge of locational social aspects in terms of spatio-temporal population distribution dynamics is considered among the most important factors for disaster impact minimization (Aubrecht et al., 2013a). This applies to both the pre-event stage for designing appropriate preparedness measures and to acute crisis situations when an event chain actually unfolds for efficient situation-aware response. The presented DynaPop population dynamics model is developed at the interface of those interlinked crisis stages and aims at providing basic input for social impact evaluation and decision support in crisis management. The model provides the starting point for assessing population exposure dynamics - thus here labeled as DynaPop-X - which can either be applied in a sense of illustrating the changing locations and numbers of affected people at different stages during an event or as ex-ante estimations of probable and maximum expected clusters of affected population (Aubrecht et al., 2013b; Freire & Aubrecht, 2012). DynaPop is implemented via a gridded spatial disaggregation approach and integrates previous efforts on spatio-temporal modeling that account for various aspects of population dynamics such as human mobility and activity patterns that are particularly relevant in picturing the highly dynamic daytime situation (Ahola et al., 2007; Bhaduri, 2008; Cockings et al., 2010). We will present ongoing developments particularly focusing on the implementation logic of the model using the emikat software tool, a data management system initially designed for inventorying and analysis of spatially resolved regional air pollutant emission scenarios. This study was performed in the framework of the EU CRISMA project. CRISMA is funded from the European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement no. 284552. REFERENCES Ahola, T., Virrantaus, K., Krisp, J

Status update: is smoke on your mind? Using social media to assess smoke exposure

Directory of Open Access Journals (Sweden)

B. Ford

2017-06-01

Full Text Available Exposure to wildland fire smoke is associated with negative effects on human health. However, these effects are poorly quantified. Accurately attributing health endpoints to wildland fire smoke requires determining the locations, concentrations, and durations of smoke events. Most current methods for assessing these smoke events (ground-based measurements, satellite observations, and chemical transport modeling are limited temporally, spatially, and/or by their level of accuracy. In this work, we explore using daily social media posts from Facebook regarding smoke, haze, and air quality to assess population-level exposure for the summer of 2015 in the western US. We compare this de-identified, aggregated Facebook dataset to several other datasets that are commonly used for estimating exposure, such as satellite observations (MODIS aerosol optical depth and Hazard Mapping System smoke plumes, daily (24 h average surface particulate matter measurements, and model-simulated (WRF-Chem surface concentrations. After adding population-weighted spatial smoothing to the Facebook data, this dataset is well correlated (R2 generally above 0.5 with the other methods in smoke-impacted regions. The Facebook dataset is better correlated with surface measurements of PM2. 5 at a majority of monitoring sites (163 of 293 sites than the satellite observations and our model simulation. We also present an example case for Washington state in 2015, for which we combine this Facebook dataset with MODIS observations and WRF-Chem-simulated PM2. 5 in a regression model. We show that the addition of the Facebook data improves the regression model's ability to predict surface concentrations. This high correlation of the Facebook data with surface monitors and our Washington state example suggests that this social-media-based proxy can be used to estimate smoke exposure in locations without direct ground-based particulate matter measurements.

Status update: is smoke on your mind? Using social media to assess smoke exposure

Science.gov (United States)

Ford, Bonne; Burke, Moira; Lassman, William; Pfister, Gabriele; Pierce, Jeffrey R.

2017-06-01

Exposure to wildland fire smoke is associated with negative effects on human health. However, these effects are poorly quantified. Accurately attributing health endpoints to wildland fire smoke requires determining the locations, concentrations, and durations of smoke events. Most current methods for assessing these smoke events (ground-based measurements, satellite observations, and chemical transport modeling) are limited temporally, spatially, and/or by their level of accuracy. In this work, we explore using daily social media posts from Facebook regarding smoke, haze, and air quality to assess population-level exposure for the summer of 2015 in the western US. We compare this de-identified, aggregated Facebook dataset to several other datasets that are commonly used for estimating exposure, such as satellite observations (MODIS aerosol optical depth and Hazard Mapping System smoke plumes), daily (24 h) average surface particulate matter measurements, and model-simulated (WRF-Chem) surface concentrations. After adding population-weighted spatial smoothing to the Facebook data, this dataset is well correlated (R2 generally above 0.5) with the other methods in smoke-impacted regions. The Facebook dataset is better correlated with surface measurements of PM2. 5 at a majority of monitoring sites (163 of 293 sites) than the satellite observations and our model simulation. We also present an example case for Washington state in 2015, for which we combine this Facebook dataset with MODIS observations and WRF-Chem-simulated PM2. 5 in a regression model. We show that the addition of the Facebook data improves the regression model's ability to predict surface concentrations. This high correlation of the Facebook data with surface monitors and our Washington state example suggests that this social-media-based proxy can be used to estimate smoke exposure in locations without direct ground-based particulate matter measurements.

TOWARDS RELIABLE AND COST-EFFECTIVE OZONE EXPOSURE ASSESSMENT: PARAMETER EVALUATION AND MODEL VALIDATION USING THE HARVARD SOUTHERN CALIFORNIA CHRONIC OZONE EXPOSURE STUDY DATA

Science.gov (United States)

Accurate assessment of chronic human exposure to atmospheric criteria pollutants, such as ozone, is critical for understanding human health risks associated with living in environments with elevated ambient pollutant concentrations. In this study, we analyzed a data set from a...

Occupational Exposure Assessment of Nanomaterials using Control Banding Tools

DEFF Research Database (Denmark)

Liguori, Biase

, are relatively advanced, and they are good foundations for an advanced exposure assessment. Considering the tiered approach for workplace assessment proposed by the OECD, these two tools could be situated, between Tier 1 (Information gathering) and Tier 2 (Basic exposure assessment). Moreover, the thesis......Nanotechnology can be termed as the “new industrial revolution”. A broad range of potential benefits in various applications for the environment and everyday life of humans can be related to the use of nanotechnology. Nanomaterials are used in a large variety of products already in the market......, and because of their novel physical and chemical characteristics, the application of nanomaterials is projected to increase further. This will inevitably increase the production of nanomaterials with potential increase of exposure for the workers which are the first in line expected to become exposed...

Nano-metal oxides: Exposure and engineering control assessment.

Science.gov (United States)

Garcia, Alberto; Eastlake, Adrienne; Topmiller, Jennifer L; Sparks, Christopher; Martinez, Kenneth; Geraci, Charles L

2017-09-01

In January 2007, the National Institute for Occupational Safety and Health (NIOSH) conducted a field study to evaluate process specific emissions during the production of ENMs. This study was performed using the nanoparticle emission assessment technique (NEAT). During this study, it was determined that ENMs were released during production and cleaning of the process reactor. Airborne concentrations of silver, nickel, and iron were found both in the employee's personal breathing zone and area samples during reactor cleaning. At the completion of this initial survey, it was suggested that a flanged attachment be added to the local exhaust ventilation system.  NIOSH re-evaluated the facility in December 2011 to assess worker exposures following an increase in production rates. This study included a fully comprehensive emissions, exposure, and engineering control evaluation of the entire process. This study made use of the nanoparticle exposure assessment technique (NEAT 2.0). Data obtained from filter-based samples and direct reading instruments indicate that reactor cleanout increased the overall particle concentration in the immediate area. However, it does not appear that these concentrations affect areas outside of the production floor. As the distance between the reactor and the sample location increased, the observed particle number concentration decreased, creating a concentration gradient with respect to the reactor. The results of this study confirm that the flanged attachment on the local exhaust ventilation system served to decrease exposure potential.  Given the available toxicological data of the metals evaluated, caution is warranted. One should always keep in mind that occupational exposure levels were not developed specifically for nanoscale particles. With data suggesting that certain nanoparticles may be more toxic than the larger counterparts of the same material; employers should attempt to control emissions of these particles at the source

Population-Based Assessment of Exposure to Risk Behaviors in Motion Pictures.

Science.gov (United States)

Sargent, James D; Worth, Keilah A; Beach, Michael; Gerrard, Meg; Heatherton, Todd F

2008-01-01

The aim of most population-based studies of media is to relate a specific exposure to an outcome of interest. A research program has been developed that evaluates exposure to different components of movies in an attempt of assess the association of such exposure with the adoption of substance use during adolescence. To assess exposure to movie substance use, one must measure both viewing time and content. In developing the exposure measure, the study team was interested in circumventing a common problem in exposure measurement, where measures often conflate exposure to media with attention to media. Our aim in this paper is to present a validated measure of exposure to entertainment media, the Beach method, which combines recognition of a movie title with content analysis of the movie for substance use, to generate population based measures of exposure to substance use in this form of entertainment.

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.

Toxicity assessment of unintentional exposure to multiple chemicals

International Nuclear Information System (INIS)

Mumtaz, M.M.; Ruiz, P.; De Rosa, C.T.

2007-01-01

Typically exposure to environmental chemicals is unintentional, and often the exposure is to chemical mixtures, either simultaneously or sequentially. When exposure occurs, in public health practice, it is prudent to ascertain if thresholds for harmful health effects are exceeded, whether by individual chemicals or by chemicals in combination. Three alternative approaches are available for assessing the toxicity of chemical mixtures. Each approach, however, has shortcomings. As the procedures of each approach are described in this paper, at various steps research needs are identified. Recently, reliance has increased on computational toxicology methods for predicting toxicological effects when data are limited. Advances in molecular biology, identification of biomarkers, and availability of accurate and sensitive methods allow us to more precisely define the relationships between multiple chemical exposures and health effects, both qualitatively and quantitatively. Key research needs are best fulfilled through collaborative research. It is through such collaborations that resources are most effectively leveraged to further develop and apply toxicity assessment methods that advance public health practices in vulnerable communities

Stakeholder attitudes towards cumulative and aggregate exposure assessment of pesticides.

Science.gov (United States)

Verbeke, Wim; Van Loo, Ellen J; Vanhonacker, Filiep; Delcour, Ilse; Spanoghe, Pieter; van Klaveren, Jacob D

2015-05-01

This study evaluates the attitudes and perspectives of different stakeholder groups (agricultural producers, pesticide manufacturers, trading companies, retailers, regulators, food safety authorities, scientists and NGOs) towards the concepts of cumulative and aggregate exposure assessment of pesticides by means of qualitative in-depth interviews (n = 15) and a quantitative stakeholder survey (n = 65). The stakeholders involved generally agreed that the use of chemical pesticides is needed, primarily for meeting the need of feeding the growing world population, while clearly acknowledging the problematic nature of human exposure to pesticide residues. Current monitoring was generally perceived to be adequate, but the timeliness and consistency of monitoring practices across countries were questioned. The concept of cumulative exposure assessment was better understood by stakeholders than the concept of aggregate exposure assessment. Identified pitfalls were data availability, data limitations, sources and ways of dealing with uncertainties, as well as information and training needs. Regulators and food safety authorities were perceived as the stakeholder groups for whom cumulative and aggregate pesticide exposure assessment methods and tools would be most useful and acceptable. Insights obtained from this exploratory study have been integrated in the development of targeted and stakeholder-tailored dissemination and training programmes that were implemented within the EU-FP7 project ACROPOLIS. Copyright © 2014 Elsevier Ltd. All rights reserved.

Probabilistic assessment of exposure to hair cosmetic products by the French population.

Science.gov (United States)

Ficheux, A S; Bernard, A; Chevillotte, G; Dornic, N; Roudot, A C

2016-06-01

Cosmetic exposure data are limited in Europe and especially in France. The aim of this study was to assess the exposure to hair cosmetics using recent consumption data (percentage of users, frequency of use and amount per use) generated for the French population (Ficheux et al., 2015, 2016). Exposure was assessed using a probabilistic method for eleven hair products: liquid shampoo, dry shampoo, conditioner, hair mask, hair serum, hair oil, styling lacquer, styling gel, styling foam, styling wax and styling spray. Exposure was assessed by sex and by age classes in adults and children. Pregnant women were also studied. For liquid shampoo, conditioner and some styling products (gel, lacquer and foam), the levels of exposure were higher than the values currently used by the Scientific Committee on Consumer Safety (SCCS). Exposure values found for styling wax and styling spray were lower than SCCS values. Exposure was assessed for the first time for dry shampoo, hair mask, hair serum and hair oil products. These new French exposure values will be useful for safety assessors and for safety agencies in order to protect the general population and these at-risk populations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Model for evaluation of the radiological exposure in an urban environment after a radioactive contamination

International Nuclear Information System (INIS)

Rochedo, Elaine Rua Rodriguez

1994-08-01

A dynamic model aimed on the assessment of the long-term consequences of an accidental contamination of an urban environments has been developed. The model was designed to assess the radiation exposure, as a function of time, of the different kinds of people that uses the contaminated environment, the relative contribution of each exposure pathway and to simulate the application of countermeasures and its effects on the reduction of surfaces contamination and on the exposure of the individuals and of the population. The model is an empirical one, mainly based on environmental data gathered after the Chernobyl and Goiania accidents, and takes into account climatic and population habits characteristic of tropical areas. The model was applied here to a contamination with the radionuclide 137 Cs but can be easily adapted to other nuclides by changes on parameter values. An analysis of the variabilities associated to the model outputs regarding population habits, different kinds of urban environment and parameters uncertainty has shown that the main source of uncertainty on model predictions is associated to a correct knowledge of population characteristics, its habits and used of the contaminated environment. (author)

Performance of GPS-devices for environmental exposure assessment.

Science.gov (United States)

Beekhuizen, Johan; Kromhout, Hans; Huss, Anke; Vermeulen, Roel

2013-01-01

Integration of individual time-location patterns with spatially resolved exposure maps enables a more accurate estimation of personal exposures to environmental pollutants than using estimates at fixed locations. Current global positioning system (GPS) devices can be used to track an individual's location. However, information on GPS-performance in environmental exposure assessment is largely missing. We therefore performed two studies. First, a commute-study, where the commute of 12 individuals was tracked twice, testing GPS-performance for five transport modes and two wearing modes. Second, an urban-tracking study, where one individual was tracked repeatedly through different areas, focused on the effect of building obstruction on GPS-performance. The median error from the true path for walking was 3.7 m, biking 2.9 m, train 4.8 m, bus 4.9 m, and car 3.3 m. Errors were larger in a high-rise commercial area (median error=7.1 m) compared with a low-rise residential area (median error=2.2 m). Thus, GPS-performance largely depends on the transport mode and urban built-up. Although ~85% of all errors were 50 m. Modern GPS-devices are useful tools for environmental exposure assessment, but large GPS-errors might affect estimates of exposures with high spatial variability.

A Spatial Model of the Mere Exposure Effect.

Science.gov (United States)

Fink, Edward L.; And Others

1989-01-01

Uses a spatial model to examine the relationship between stimulus exposure, cognition, and affect. Notes that this model accounts for cognitive changes that a stimulus may acquire as a result of exposure. Concludes that the spatial model is useful for evaluating the mere exposure effect and that affective change does not require cognitive change.…