Questions related to test capabilities identified in this document and additional assistance in ...... Pesticide analysis; glyphosate. Carbamates ... Method. Total Suspended Solids. 160.2. TCL-Pesticide/PCBs(P/PCBs) 8081. Total Dissolved ...

Pesticides have been suspected to act as endocrine disruptive compounds (EDCs) through several mechanisms of action, however data are still needed for a number of currently used pesticides. In the present study, 30 environmental pesticides selected from different chemical classes (azole, carbamate, ...

While information exists regarding inhibition of cholinesterase (ChE) activity, little is known about neurophysiological changes produced by a mixture of N-methyl carbamate pesticides. Previously, we reported that acute treatment with propoxur or carbaryl decreased the duration o...

A physiologically-based pharmacokinetic (PBPK) model for a mixture of N-methyl carbamate pesticides was developed based on single chemical models. The model was used to compare urinary metabolite concentrations to levels from National Health and Nutrition Examination Survey (NHA...

This paper describes method validation for determination of more than 40 pesticides in apples using a GC technique. Target compounds belonged to the organochlorine, organophosphorus, carbamates, pyrethroids, triazoles, dicarboximides and strobilurins groups, among others. Sample preparation consisted of acetone extraction and subsequent cleanup/concentration by SPE with a polymer-based sorbent. Single quadrupole GC-MS operating in SIM mode and electron impact ionization was used for identification and quantification of the pesticides. Average recoveries for analytes ranged between 70 and 110% at three fortification levels - 0.01, 0.1 and 0.2 mg kg-1. Relative standard deviations were lower than 20% for all tested compounds. Calculated limits of detection and limits of quantification were b...

We investigated the possibility of a method to monitor pesticides in water by assaying effects of organophosphorus and carbamate pesticides upon acetylcholinesterase (AChE) activity. The procedure is very simple as follows; the human red blood cell suspension was added to sample water and then AChE activity was determined by autoanalyzer. Using this method, we assayed 33 kinds of organophosphorus pesticide, 8 kinds of its oxon, and 12 kinds of carbamate pesticide. Nineteen out of the 33 organophosphorus pesticides, 7 out of the 8 oxons of organophosphorus pesticide, and all of the 12 carbamate pesticides tested were detected at the concentration of less than 1mg{center_dot}l{sup -1}. Even at the concentration 100ng{center_dot}l{sup -1}, EDDP, Benfracarb, Chlorpyrifos oxon, Isoxathion oxon and Diazinon oxon were detected. In addition, 13 pesticides were detected at the concentration of 100ng{center_dot}l{sup -1} in the water containing 1mg{center_dot}l{sup -1} chlorine, which is equivalent to the chlorine level in water disinfection process. This analytical method, although the detectable concentration levels are varied widely according to the type of pesticides, is capable of detecting many of organophosphorus and carbamate pesticides in water. 12 refs., 1 fig., 5 tabs.

A simple liquid chromatography/mass spectrometry (LC/MS) approach for the determination of widely used representatives of polar/thermolabile pesticides in fruits was developed and validated. The group of pesticides comprised benzimidazoles and azoles (carbendazim, thiabendazole, imazalil, propiconazole, prochloraz, epoxiconazole, flusilazole, tebuconazole, bitertanol); N-methylcarbamates (carbaryl, carbofuran, methiocarb); and phenylureas and benzoylphenylureas (linuron, diflubenzuron, triflumuron, teflubenzuron, flufenoxuron). Matrixes (apple, apricot) were extracted with acetonitrile and crude extracts were cleaned up by solid-phase extraction (SPE) using either mixed cation exchange or hydrophilic lipophilic balance cartridges. LC separation of pesticides was performed on a reversed-phase column, Discovery C18. Electrospray ionization and ion trap MS/MS detection were applied. For most pesticides, overall recoveries ranged from 75 to 122%, and repeatability (as relative standard deviation) from 5 repetitive determinations of recovery ranged from 3 to 21%. Carbofuran was the only compound for which recovery was not satisfactory due to its loss in the SPE cleanup step. Limits of detection were 0.1-3 microg/kg for benzimidazole and azole fungicides and carbamate insecticides. For urea insecticides, detection limits were slightly higher (3-10 microg/kg). PMID:12852583

A new multiresidue method has been developed and validated for the simultaneous extraction of more than two hundred pesticides, including non-polar and polar pesticides (carbamates, organochlorine, organophosphorous, pyrethroids, herbicides and insecticides) in urine at trace levels by gas and ultra high pressure liquid chromatography coupled to ion trap and triple quadrupole mass spectrometry, respectively (GC-IT-MS/MS, UHPLC-QqQ-MS/MS). Non-polar and polar pesticides were simultaneously extracted from urine samples by a simple and fast solid phase extraction (SPE) procedure using C(18) cartridges as sorbent, and dichloromethane as elution solvent. Recovery was in the range of 60-120%. Precision values expressed as relative standard deviation (RSD) were lower than 25%. Identification and confirmation of the compounds were performed by the use of retention time windows, comparison of spectra (GC-amenable compounds) or the estimation of the ion ratio (LC-amenable compounds). For GC-amenable pesticides, limits of detection (LODs) ranged from 0.001 to 0.436 ?g L(-1) and limits of quantification (LOQs) from 0.003 to 1.452 ?g L(-1). For LC-amenable pesticides, LODs ranged from 0.003 to 1.048 ?g L(-1) and LOQs ranged from 0.011 to 3.494 ?g L(-1). Finally, the optimized method was applied to the analysis of fourteen real samples of infants from agricultural population. Some pesticides such as methoxyfenozide, tebufenozide, piperonyl butoxide and propoxur were found at concentrations ranged from 1.61 to 24.4 ?g L(-1), whereas methiocarb sulfoxide was detected at trace levels in two samples. PMID:21645688

A comprehensive multi-residue method for the chromatographic separation and accurate mass identification of 101 pesticides and their degradation products using liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) is reported here. Several classes of compounds belonging to different chemical families (triazines, organophosphorous, carbamates, phenylureas, neonicotinoids, etc.) were carefully chosen to cover a wide range of applications in the environmental field. Excellent chromatographic separation was achieved by the use of narrow accurate mass windows (0.05 Da) in a 30 min interval. Accurate mass measurements were always below 2 ppm error for all the pesticides studied. A table compiling the accurate masses for 101 compounds together with the accurate mass of several fragment ions is included. At least the accurate mass for one main fragment ion for each pesticide was obtained to achieve the minimum of identification points according to the 2002/657/EC European Decision, thus fulfilling the EU point system requirement for identification of contaminants in samples. The method was validated with vegetable samples. Calibration curves were linear and covered two orders of magnitude (from 5 to 500 microg/L) for most of the compounds studied. Instrument detection limits (LODs) ranged from 0.04 to 150 microg/kg in green-pepper samples. The methodology was successfully applied to the analysis of vegetable and water samples containing pesticides and their degradation products. This paper serves as a guide for those working in the analytical field of pesticides, as well as a powerful tool for finding non-targets and unknowns in environmental samples that have not been previously included in any of the routine target multi-residue methods. PMID:17996875

The toxicity of carbaryl, chlorpyrifos, dimethoate and profenofos to the freshwater shrimp, Paratya australiensis was assessed by measuring acetylcholinesterase (AChE) inhibition after 96h exposures. Shrimp exposed to these pesticides exhibited significant AChE inhibition, with mortality in shrimp corresponding to 70–90% AChE inhibition. The sensitivity of P. australiensis to the four pesticides based on AChE inhibition can be given as chlorpyrifos>profenofos>carbaryl>dimethoate. Recovery of AChE activity was followed in shrimp after 96h exposures to carbaryl, chlorpyrifos and dimethoate. Recovery after exposure to the carbamate pesticide carbaryl was more rapid than for the two organophosphorus pesticides, chlorpyrifos and dimethoate. The slow recovery of d...

The presence of pesticide residues in Brassica vegetables (365 samples) produced in north-eastern Poland (2006-2009) was determined and their health risks assessed. The analytical procedure was developed to examine of 130 pesticides of different chemical classes (chloroorganic, phosphoroorganic, carbamates, strobilurines, neonicotinoids, amides, pyrimidines, benzimidazoles, imidazoles and triazoles) in broccoli, Brussels sprouts, cauliflower, head and Chinese cabbage. Pesticides were extracted using matrix solid phase dispersion (MSPD) and analyzed by gas chromatography (GC) with dual detection system: electron capture (ECD) and nitrogen-phosphorus (NPD). Linearity (R^2 >= 0.997) was good over the concentration range from 2.5 to 0.001 mg/kg for all the pesticides, and instrumental detectio...

This project is still in its early phases. Future work in this area will involve theoretical analyses of the limits of dose-additivity assumptions, and physiologically-based pharmacokinetic and pharmacodynamic (PBPK/PD) models for n-methyl carbamate and pyrethroid pesticides (in ...

Obsolete pesticides were stored in Poland from the middle sixties until the late eighties of the 20th century mostly in underground disposal sites, called ''pesticide burial grounds'' or ''pesticide tombs''. The total amount of pesticide waste and packaging materials disposed of in these landfills exceeded 20000Mg. Typically, the content of a pesticide tomb was dominated by organochlorine pesticides (comprising 10-100% of the total waste volume) with DDT as the prevailing compound. Other pesticide types, such as phosphoroorganic, carbamate insecticides, dinitrophenols, phenoxyacids, and inorganic compounds were stored in smaller quantities, usually not exceeding 10-20% of the total waste volume. With the growing awareness of the threats that these landfills posed to the environment, the fi...

Organophosphorus and carbamate pesticides are acetylcholinesterase-inhibiting pesticides and as such have a common mode of action. We assessed the cumulative acute exposure of the population of Denmark to 25 organophosphorus and carbamate pesticide residues from the consumption of fruit, vegetables and cereals. The probabilistic approach was used in the assessments. Residue data obtained from the Danish monitoring programme carried out in the period 2004-2007, which included 6704 samples of fruit, vegetables and cereals, were used in the calculations. Food consumption data were obtained from the nationwide dietary survey conducted in 2000-2002. Contributions from 43 commodities were included in the calculations. We used the relative potency factor (RPF) approach to normalize the toxicity o...

Chemical residues, such as insecticides and anthelmintics, are frequently redistributed from the aquatic environment to marine species. This work reports on a fast validated protocol for the analysis of azamethiphos, three avermectins, two carbamates and two benzoylurea pesticides and chemotherapeutic agents in seaweeds based on pressurized liquid extraction and separation of analytes by liquid chromatography coupled with tandem mass spectrometry. The variables affecting the efficiency of pressurized liquid extraction, including temperature, number of extraction cycles, static extraction time and percent acetonitrile flush volume, were studied using a Doehlert design. The optimum parameters were 100 °C and one cycle of 3 min with 70 % acetonitrile. Adequate in-cell clean-up of the seaweeds was achieved using 0.8 g of Florisil over 0.1 g of graphitized carbon black on the bottom of the cell. The optimized method was validated using an analyte-free seaweed sample fortified at different concentrations. The limits of quantification ranged from 3.6 ?g kg(-1) (azamethiphos) to 31.5 ?g kg(-1) (abamectin). The recovery was from 87 to 120 % in most cases at different spiking levels. Finally, the reproducibility of the method expressed as the relative standard deviation and evaluated at concentrations of 10 and 50 ?g kg(-1) was in the range 9-14.3 % and 6.1-12.3 %, respectively. The applicability of the method was evaluated with five commercial and 12 wild edible seaweeds, and four target compounds were detected in two wild seaweeds at a concentration below the quantification limit. PMID:22638882

The suitability of a mixed-mode sorbent made up of admicelles of sodium dodecyl sulphate (SDS) and tetrabutylammonium (TBA) to extract and preserve pesticides from river and underground water was assessed. Pesticides belonging to different structural groups (i.e. triazines, carbamates, phenylureas, anilides, chloroacetanilides, organophosphorus and phenoxyacids), most of them well known by their instability, were selected for this purpose. Extraction of pesticides with the admicellar sorbent was optimized. Percolation of 250mL of sample through the SPE cartridge, elution with 1mL of methanol (neutral and basic pesticides) or 2mL of 0.3M NaOH:methanol (90:10, v/v) (acidic pesticides) and direct analysis of the extract by liquid chromatography/UV detection, permitted to obtain method detecti...

The goal of this study was to develop a method to detect pesticide adducts in tryptic digests of butyrylcholinesterase in human plasma from patients poisoned by pesticides. Adducts to butyrylcholinesterase in human serum may serve as biomarkers of pesticide exposure because organophosphorus and carbamate pesticides make a covalent bond with the active site serine of butyrylcholinesterase. Serum samples from five attempted suicides (with dichlorvos, Aldicarb, Baygon and an unknown pesticide) and from one patient who accidentally inhaled dichlorvos were analyzed. Butyrylcholinesterase was purified from 2 ml serum by ion exchange chromatography at pH 4, followed by procainamide affinity chromatography at pH 7. The purified butyrylcholinesterase was denatured, digested with trypsin and the mod...

A cross sectional study was conducted to investigate the effects of pesticide exposure (organophosphate and carbamate) using nerve conductive velocity, current perception threshold (CPT). Cluster random sampling was employed to recruit 64 paddy farmers and 22 fishermen in June 2006. The duration of pesticide exposure was between (5-20) years. The CPT values were measured using Neurometer CPT/Eagle, on the index finger and the great toe with three neuroselective frequencies range (2000, 250, and 5 Hz). The results showed that at the three different frequencies, the CPT values were significantly elevated among farmers on both the medial and peroneal nerves (P < .002). The measurement of CPT can be used as a biomarker to determine and monitor the effects of organophosphate and carbamate exposure among workers who may have been exposed. PMID:19533876

Bioterrorism poses a real threat to the public health and national security, and the restoration of affected facilities after a chemical, biological or radiological attack is a major concern. This paper reviewed aspects of a project conducted to collect information, test and validate procedures for site restoration after a terrorist attack. The project began with a review of existing technology and then examined new technologies. Restoration included pickup, neutralization, decontamination, removal and final destruction and deposition of contaminants as well as cleaning and neutralization of material and contaminated waste from decontamination. The project was also intended to test existing concepts and develop new ideas. Laboratory scale experiments consisted of testing, using standard laboratory techniques. Radiation decontamination consisted of removal and concentration of the radioisotopes from removal fluid. General restoration guidelines were provided, as well as details of factors considered important in specific applications, including growth conditions and phases of microorganisms in biological decontamination, or the presence of inhibitors or scavengers in chemical decontamination. Various agents were proposed that were considered to have broad spectrum capability. Test surrogates for anthrax were discussed. The feasibility of enhanced oxidation processes was examined in relation to the destruction of organophosphorus, organochlorine and carbamate pesticides. The goal was to identify a process for the treatment of surfaces contaminated with pesticides. Tests included removal from carpet, porous ceiling tile, steel plates, and floor tiles. General radiation contamination procedures and techniques were reviewed, as well as radiological decontamination waste treatment. It was concluded that there is no single decontamination technique applicable for all contaminants, and decontamination methods depend on economic, social and health factors. The amount of waste generated by decontamination is a major feasibility factor. Waste volume should be minimized to avoid high costs. It was suggested that extensive testing should be continued, as many of the ideas have not been tried except on ideal targets and surfaces. 11 refs., 14 figs.

Recently, it has been observed in the authors' laboratory that growth, nitrogen fixation, protein content of cyanobacteria Nostoc muscorum were reduced by methylparathion and benthiocarb treatment. Though many works on toxicity of pesticides on cyanobacteria, specially on growth, photosynthesis and nitrogen fixation are available, the effects of pesticides on antioxidant enzyme levels is still unclear. In this communication, studies have been presented on the effects of organophosphate insecticide methyl-parathione and carbamate herbicide benthiocarb, on glutathione content, glutathione reductase (GR) and superoxide dismutase (SOD) activities of filamentous, nitrogen-fixing cyanobacteria Nostoc muscorum.

Organophosphates and carbamates (OPs/CMs) are known for their acetylcholinesterase inhibiting character. A cross-sectional study of pesticide handling practices and self-perceived symptoms of acute pesticide poisoning was conducted using questionnaire-based interviews with 89 pesticide sprayers in Boeung Cheung Ek (BCE) Lake, Phnom Penh, Cambodia. The study showed that 50% of the pesticides used belonged to WHO class I + II and personal protection among the farmers were inadequate. A majority of the farmers (88%) had experienced symptoms of acute pesticide poisoning, and this was significantly associated with the number of hours spent spraying with OPs/CMs (OR = 1.14, CI 95%: 1.02-1.28). The higher educated farmers reduced their risk of poisoning by 55% for each extra personal protective measure they adapted (OR = 0.45, CI 95%: 0.22-0.91). These findings suggest that improving safe pesticide management practices among the farmers and enforcing the effective banning of the most toxic pesticides will considerably reduce the number of acute pesticide poisoning episodes.

Pesticides are a large group of structurally diverse toxic chemicals. The toxicity may be modified by cytochrome P450 (CYP) enzyme activity. In the current study, we have investigated effects and mechanisms of 24 structurally varying pesticides on human CYP expression. Many pesticides were found to efficiently activate human pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Out of the 24 compounds tested, 14 increased PXR- and 15 CAR-mediated luciferase activities at least 2-fold. While PXR was predominantly activated by pyrethroids, CAR was, in addition to pyrethroids, well activated by organophosphates and several carbamates. Induction of CYP mRNAs and catalytic activities was studied in the metabolically competent, human derived HepaRG cell line. CYP3A4 mRNA was induced most powerfully by pyrethroids; 50 ?M cypermethrin increased CYP3A4 mRNA 35-fold. CYP2B6 was induced fairly equally by organophosphate, carbamate and pyrethroid compounds. Induction of CYP3A4 and CYP2B6 by these compound classes paralleled their effects on PXR and CAR. The urea herbicide diuron and the triazine herbicide atrazine induced CYP2B6 mRNA more than 10-fold, but did not activate CAR indicating that some pesticides may induce CYP2B6 via CAR-independent mechanisms. CYP catalyzed activities were induced much less than the corresponding mRNAs. At least in some cases, this is probably due to significant inhibition of CYP enzymes by the studied pesticides. Compared with human CAR activation and CYP2B6 expression, pesticides had much less effect on mouse CAR and CYP2B10 mRNA. Altogether, pesticides were found to be powerful human CYP inducers acting through both PXR and CAR. PMID:22310298

The correlation of predicted environmental concentrations (PEC) with cholinesterase activity inhibition detected in soil extracts was determined. PEC was derived from organophosphate (OP) and carbamate (CA) compounds applied to a flower crop area. Samples of surface soil (0 - 30 cm in depth) and subsurface soil (30 to 60 cm in depth) were taken from a flower crop area in which OP pesticides such as acephate ((RS)-N-[methoxy(methylthio)phosphinoyl]acetamide), dimethoate (2-dimethoxyphosphinothioylthio-N-methylacetamide) and methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate), and CA pesticides such as carbendazim (methyl benzimidazol-2-ylcarbamate), carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) and methomyl (S-methyl (EZ)-N-(methylcarbamoyloxy) thioacetimidate) were applied for two years. Weekly loads of these pesticides were registered to estimate the annual load of each compound. Physicochemical analysis and relative inhibition of cholinesterasic activity were measured for each soil sample. PEC values were estimated with Pesticide Analytical Model (PESTAN), a leach model, for each pesticide using soil sample data obtained from physicochemical analysis. From all pesticides tested, only acephate and methomyl showed a significant correlation (p pesticides. Further studies could be developed to measure acephate and methomyl concentrations to reduce their environmental impact. PMID:20390953

Abstract in english Pesticides, aflatoxins, and nutritional analyses of commercial citrus pulp pellets in Brazil were performed in samples from São Paulo State. They were stored during 86 days and were processed for detection of toxic agents. Residual pesticides (organochlorinated, organophosphorus, pyrethoids, carbamates, chloroalquil tio fungicides, triazols, and the miscellaneous compound propargit) and aflatoxins (B1, B2, G1 and G2) were assayed at 0, 43 and 86 days of storage. It was n (more) ot detected residual pesticide and aflatoxins in any sample. The analysis indicated reduced levels of phosphorous and high values of calcium. Assessment of micro minerals indicated the presence of aluminum, barium, titanium, cooper, manganese, thorium, vanadium, zinc, lanthanum, samarium, cobalt, antimony, arsenic, and scandium.

Twenty chiral pesticides were tested, of which seven samples were directly separated by HPLC using cellulose tris-3,5-dimethyl carbamate (CDMPC) chiral stationary phase under RP conditions. The influence of mobile phase composition and column temperatures from 0degreeC to 40degreeC on the separations were investigated. The mobile phases were methanol/water or ACN/water at a flow rate of 0.8 mL/min with UV detection at 230 or 210 nm. Epoxiconazole, terallethrin, benalaxyl, and diclofop-methyl were observed to obtain the baseline separation under suitable conditions and other pesticides pyriproxyfen, lactofen, and quizalofop-ethyl were separated partially. The retention factors (k) and selectivity factor (a) for the enantiomers of most investigated pesticides decreased upon increasing the te...

The European Parliament recently approved a new EU regulation aimed at eliminating the use of pesticides that have unwanted endocrine-disrupting properties. The test criteria for these chemicals are slated to be finalized by 2013. For this reason, in this review, we have evaluated the meta data of lists and databanks that address pesticides with potentially endocrine-disrupting properties, and have checked which of the 250 active ingredients currently in use in Germany are affected. Azoles, dithio-carbamates/carbamates, and pyrethroids were most frequently rated as endocrine-active ingredients. In Germany, assessments have shown that total environmental pesticide emission is equivalent to approximately 0.1% of total pesticide use.Courtyard drainage and field runoff are regarded to constitute the most important sources of pesticide emission into the aquatic environment. In addition, in several investigations of drinking- and groundwater contamination, various pesticide-active ingredients and their metabolites were confirmed to be contaminants. Water suppliers recorded the following pesticides or their metabolites as being most frequently detected in drinking water: atrazine, desethylatrazine, diuron, simazine, isoproturon,and its dichlobenil metabolite 2,6-dichlorobenzamide. Surface water contamination results mainly from substances that are no longer approved by EU pesticide regulation. The most frequently detected pesticides in streaming waters that are still authorized were bentazone, diuron, glyphosate, isoproturon, MCPA, mecoprop,metamitron, pendimethalin, and tebuconazole. Pesticide residues in comestible goods of herbal origin are periodically detected in all EU member countries. The European Commission recently published results showing that 54% of all monitoring samples were devoid of positive findings. Of samples showing detectable residues, 42% were below, and 4.4% exceeded the EUMRLs. Monitoring data over a 10-year period revealed that the percentage of foodstuff without detectable pesticide residues has continuously decreased from 64 to 51.5%. In Germany, herbal samples mainly contained residues of maneb, iprodion,procymidone and deltamethrin. Notwithstanding these detections, chronic health risk evaluations indicated that there were no violations of ADI values. However,for carbaryl, methomyl, and procymidone, ARfDs were exceeded substantially for intake of grapefruit and bell peppers. As a result, the EU withdrew the methomyl authorization in 2008 and revised procymidone guideline values. PMID:21541850

We have developed a simple method for the microextraction of the carbamate pesticides carbofuran, pirimicarb, and carbaryl. It is termed ionic liquid magnetic bar microextraction (ILMB-ME) and based on an ionic liquid deposited on a magnetic stirrer bar placed in a sealed short PCR tube into which microholes where pinned. When placed in a vial containing the aqueous sample solution, the ILMB tumbles freely in the aqueous solution and the carbamates are extracted into the ionic liquid phase which then was determined by HPLC. The enrichment factors for carbofuran, pirimicarb, and carbaryl are 107, 94, 95, respectively. The limits of detection, calculated as three times the signal-to-noise ratio (S/N), are 1.4??g?L?1 for carbofuran, 3.4??g?L?1 for pirimicarb, and 1.7??g?L?1 for carbaryl. The ...

Pesticides are a collective term for a wide array of chemicals intended to kill unwanted insects, plants, molds, and rodents. Food, water, and treatment in the home, yard, and school are all potential sources of children's exposure. Exposures to pesticides may be overt or subacute, and effects range from acute to chronic toxicity. In 2008, pesticides were the ninth most common substance reported to poison control centers, and approximately 45% of all reports of pesticide poisoning were for children. Organophosphate and carbamate poisoning are perhaps the most widely known acute poisoning syndromes, can be diagnosed by depressed red blood cell cholinesterase levels, and have available antidotal therapy. However, numerous other pesticides that may cause acute toxicity, such as pyrethroid and neonicotinoid insecticides, herbicides, fungicides, and rodenticides, also have specific toxic effects; recognition of these effects may help identify acute exposures. Evidence is increasingly emerging about chronic health implications from both acute and chronic exposure. A growing body of epidemiological evidence demonstrates associations between parental use of pesticides, particularly insecticides, with acute lymphocytic leukemia and brain tumors. Prenatal, household, and occupational exposures (maternal and paternal) appear to be the largest risks. Prospective cohort studies link early-life exposure to organophosphates and organochlorine pesticides (primarily DDT) with adverse effects on neurodevelopment and behavior. Among the findings associated with increased pesticide levels are poorer mental development by using the Bayley index and increased scores on measures assessing pervasive developmental disorder, inattention, and attention-deficit/hyperactivity disorder. Related animal toxicology studies provide supportive biological plausibility for these findings. Additional data suggest that there may also be an association between parental pesticide use and adverse birth outcomes including physical birth defects, low birth weight, and fetal death, although the data are less robust than for cancer and neurodevelopmental effects. Children's exposures to pesticides should be limited as much as possible. PMID:23184105

Exposure to organophosphate and carbamate pesticides can lead to neurotoxic effects through inhibition of cholinesterase enzymes. The paraoxonase (PON1) enzyme can detoxify oxon derivatives of some organophosphates. Lower PON1, acetylcholinesterase, and butyrylcholinesterase activities have been reported in newborns relative to adults, suggesting increased susceptibility to organophosphate exposure in young children. We determined PON1, acetylcholinesterase, and butyrylcholinesterase activities in Mexican–American mothers and their 9-year-old children (n=202 pairs) living in an agricultural community. We used Wilcoxon signed-rank tests to compare enzymatic activities among mothers and their children, and analysis of variance to identify factors associated with enzyme activities. Subs...

Previous studies in rainbow trout have shown that acclimation to hypersaline environments enhances the toxicity to thioether organophosphate and carbamate pesticides. In order to determine the role of biotransformation in this process, the metabolism of the thioether organophosphate biocide, fenthion was evaluated in microsomes from gills, liver and olfactory tissues in rainbow trout (Oncorhynchus mykiss) acclimated to freshwater and 17? salinity. Hypersalinity acclimation increased the formation of fenoxon and fenoxon sulfoxide from fenthion in liver microsomes from rainbow trout, but not in gills or in olfactory tissues. NADPH-dependent and independent hydrolysis was observed in all tissues, but only NADPH-dependent fenthion cleavage was differentially modulated by hypersalinity in liver...

Abstract in english This paper describes the use of pesticides in agriculture. Research has shown that significant quantities of pesticide residues have been found in many types of foods. Thus, an overview is given of pesticide residue determinations in fruits and vegetables, with special attention to apples. The toxicity and the adverse effects possibly caused by the exposure of these compounds are alerting the scientific community to develop studies about the validation of analytical metho (more) ds for multiresidue pesticide determination in these samples. This review shows that pesticide-residue determination in apples is becoming a very important and challenging issue.

The suitability of a mixed-mode sorbent made up of admicelles of sodium dodecyl sulphate (SDS) and tetrabutylammonium (TBA) to extract and preserve pesticides from river and underground water was assessed. Pesticides belonging to different structural groups (i.e. triazines, carbamates, phenylureas, anilides, chloroacetanilides, organophosphorus and phenoxyacids), most of them well known by their instability, were selected for this purpose. Extraction of pesticides with the admicellar sorbent was optimized. Percolation of 250 mL of sample through the SPE cartridge, elution with 1 mL of methanol (neutral and basic pesticides) or 2 mL of 0.3M NaOH:methanol (90:10, v/v) (acidic pesticides) and direct analysis of the extract by liquid chromatography/UV detection, permitted to obtain method detection limits in the range 2-60 ng L(-1). Their degradation on the SPE cartridges after sample percolation was investigated under a variety of experimental conditions, namely darkness, natural illumination and different temperatures (room temperature, 4 °C and -20 °C) for 3 months. Under darkness, most of pesticides were stable for 1 month at room temperature and 3 months at 4 °C. Only atriazine and clorfenvinfos did not follow this general behaviour. No influence of matrix components on the stabilization of pesticides in the admicellar sorbent was observed. The stabilizing capability of surfactant aggregates surpassed that of C18 and black carbon and was similar to that obtained in some polymeric materials, which have the disadvantage of requiring large volumes of solvents for analyte elution. The stabilization of pesticides on the admicellar sorbent was long enough to permit easy shipping and storage of the cartridges in monitorization campaigns. PMID:22727328

Pesticide transport models are tools used to develop improved pesticide management strategies, study pesticide processes under different conditions (management, soils, climates, etc) and illuminate aspects of a system in need of more field or laboratory study. This paper briefly overviews RZWQM history and distinguishing features, overviews key RZWQM components and reviews RZWQM validation studies. RZWQM is a physically based agricultural systems model that includes sub-models to simulate: infiltration, runoff, water distribution and chemical movement in the soil; macropore flow and chemical movement through macropores; evapotranspiration (ET); heat transport; plant growth; organic matter/nitrogen cycling; pesticide processes; chemical transfer to runoff; and the effect of agricultural management practices on these processes. Research to date shows that if key input parameters are calibrated, RZWQM can adequately simulate the processes involved with pesticide transport (ET, soil-water content, percolation and runoff, plant growth and pesticide fate). A review of the validation studies revealed that (1) accurate parameterization of restricting soil layers (low permeability horizons) may improve simulated soil-water content; (2) simulating pesticide sorption kinetics may improve simulated soil pesticide concentration with time (persistence) and depth and (3) calibrating the pesticide half-life is generally necessary for accurate pesticide persistence simulations. This overview/review provides insight into the processes involved with the RZWQM pesticide component and helps identify model weaknesses, model strengths and successful modeling strategies. PMID:15025234

The correlation of predicted environmental concentrations (PEC) with cholinesterase activity inhibition detected in soil extracts was determined. PEC was derived from organophosphate (OP) and carbamate (CA) compounds applied to a flower crop area. Samples of surface soil (0 - 30 cm in depth) and subsurface soil (30 to 60 cm in depth) were taken from a flower crop area in which OP pesticides such as acephate ((RS)-N-[methoxy(methylthio)phosphinoyl]acetamide), dimethoate (2-dimethoxyphosphinothioylthio-N-methylacetamide) and methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate), and CA pesticides such as carbendazim (methyl benzimidazol-2-ylcarbamate), carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) and methomyl (S-methyl (EZ)-N-(methylcarbamoyloxy) thioacetim...

A multiresidue method was developed for the quantification and confirmation of 70 pesticides in paddy field water. After its filtration, water was injected directly in a liquid chromatograph coupled to a hybrid triple quadrupole-linear ion trap-mass spectrometer (QqLIT). The list of target analytes included organophosphates, phenylureas, sulfonylureas, carbamates, conazoles, imidazolinones and others compounds widely used in different countries where rice is cropped. Detection and quantification limits achieved were in the range from 0.4 to 80ngL^-^1 and from 2 to 150ngL^-^1, respectively. Correlation coefficients for the calibration curves in the range 0.1-50mgL^-^1 were higher than 0.99 except for diazinon (0.1-25mgL^-^1). Only 9 pesticides presented more than 20% of signal suppression/e...

Although natural populations may evolve resistance to anthropogenic stressors such as pollutants, this evolved resistance may carry costs. Using an experimental evolution approach, we exposed different Daphnia magna populations in outdoor containers to the carbamate pesticide carbaryl and control conditions, and assessed the resulting populations for both their resistance to carbaryl as well as their susceptibility to infection by the widespread bacterial microparasite Pasteuria ramosa. Our results show that carbaryl selection led to rapid evolution of carbaryl resistance with seemingly no cost when assessed in a benign environment. However, carbaryl-resistant populations were more susceptible to parasite infection than control populations. Exposure to both stressors reveals a synergistic effect on sterilization rate by P. ramosa, but this synergism did not evolve under pesticide selection. Assessing costs of rapid adaptive evolution to anthropogenic stress in a semi-natural context may be crucial to avoid too optimistic predictions for the fitness of the evolving populations. PMID:21884064

Water is a necessity for life. Currently, because of different contaminations in tap water, most people prefer using bottled mineral waters. Pesticides (e.g., organophophorous, carbamates, etc.) are among the most dangerous chemicals that may be found in drinking waters, which can cause long- and short-term complications. Because all people consume at least 2 L of water per day, water-quality monitoring is vital. In this study, we determined the concentration of three pesticides (aldicarb, parathion, and thiobencarb) in 13 tap-water samples collected from 13 different urban areas and 10 samples of bottled mineral water in Mashhad, a major city in northeast Iran. Samples were analyzed by gas chromatography coupled with a pulsed flame photometric detector after solid-phase extraction. Result...

In Brazil, in the last 20 years, dietary risk assessments have been conducted on pesticides, mycotoxins, food additives, heavy metals (mainly mercury), environmental contaminants (mainly DDT) and acrylamide, a compound formed during food processing. The objectives of this paper were to review these studies, discuss their limitations and uncertainties and identify the most critical chemicals that may pose a health risk to Brazilian consumers. The studies have shown that the cumulative intake of organophosphorus and carbamate pesticides by high consumers of fruits and vegetables may represent a health concern (up to 169% of the ARfD), although the benefits of consuming large portions of those foods most probably overcome the risks. High consumers of maize products may also be at risk due to ...

The photocatalytic treatment of soil washing wastes containing the pesticide swep and three different surfactants: sodium dodecylsulfate (SDS), hexadecyltrimethylammonium bromide (HTAB) and polyoxyethylene(8) dodecyl ether (C12E8), has been investigated. Better extraction performances of swep (methyl-N-(3,4-dichlorophenyl)carbamate) from contaminated soil samples have been obtained using aqueous SDS solutions. The pesticide abatement in the wastes, performed by photocatalysis in the presence of irradiated TiO2 dispersions, was faster in the presence of SDS and slower in the presence of HTAB, whereas a marked degradation inhibition was observed when C12E8 solutions were used. The monitoring of end products formation in water, together with a detailed MS examination of the transient intermed...

A simple and fast method of low-density extraction solvent-based solvent terminated dispersive liquid-liquid microextraction (ST-DLLME) was developed for the highly sensitive determination of carbamate pesticides in the water samples by gas chromatography-tandem mass spectrometry (GC-MSMS). After dispersing, the obtained emulsion cleared into two phases quickly when an aliquot of acetonitrile was introduced as a chemical demulsifier into the aqueous bulk. Therefore, the developed procedure does not need centrifugation to achieve phase separation. It was convenient for the usage of low-density extraction solvents in DLLME. Under the optimized conditions, the limits of detection for all target carbamate pesticides were in range of 0.001-0.50 ng mL(-1) and the precisions were in the range of 2.3-6.8% (RSDs, 2 ng mL(-1), n=5). The proposed method has been successfully applied to the analysis of real water samples and good spiked recoveries over the range of 94.5-104% were obtained. PMID:20060535

Validation experiments were conducted of a simple, fast, and inexpensive method for the determination of 229 pesticides fortified at 10-100 ng/g in lettuce and orange matrices. The method is known as the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for pesticide residues in foo...

We studied the influence of some factors on plasma butyrylcholinesterase activity (BChE) and we assessed the health status of agricultural workers and looked for the effects of chronic exposure to pesticides, in the aim to determinate factors that must be considered for interpretation of BChE, for occupational monitoring of workers exposed to pesticides. The study was carried out in 110 workers from the Sahel region of Tunisia exposed to pesticides and in 97 controls. All individuals have undergone clinical examination. BChE activity was measured by spectrophotometric method. The mean of BChE activity of workers was significantly lower than that of control group (P?carbamates mixture were implicated in significant decreases of BChE activity and can be considered as risk factors of cholinergic toxic effects. Thus, BChE activity is a useful indicator to monitor workers chronically exposed to pesticides. However, it should be accompanied by periodical health examination, taking into account risk factors, for an early identification of workers at increased risk. PMID:21464008

An amperometric biosensor for highly selective and sensitive determination of methyl parathion (MP) was developed based on dual-signal amplification: (1) a large amount of introduced enzyme on the electrode surface and (2) synergistic effects of nanoparticles towards enzymatic catalysis. The fabrication process includes (1) electrochemical deposition of gold nanoparticles by a multi-potential step technique at multiwalled carbon nanotube (MWCNT) film pre-cast on a glassy carbon electrode and (2) immobilization of methyl parathion degrading enzyme (MPDE) onto a modified electrode through CdTe quantum dots (CdTe QDs) covalent attachment. The introduced MWCNT and gold nanoparticles significantly increased the surface area and exhibited synergistic effects towards enzymatic catalysis. CdTe QDs are further used as carriers to load a large amount of enzyme. As a result of these two important enhancement factors, the proposed biosensor exhibited extremely sensitive, perfectly selective, and rapid response to methyl parathion in the absence of a mediator. The detection limit was 1.0 ng/mL. Moreover, since MPDE hydrolyzes pesticides containing the P-S bond, it showed high selectivity for detecting MP and many interfering compounds, such as carbamate pesticides. Other organophosphorous pesticides and oxygen-containing inorganic ions (SO(4)(2-), NO(3)(-)) did not interfere with the determination. The proposed MPDE biosensor presents good reproducibility and stability, and the MPDE is not poisoned by organophosphate pesticides. Unlike cholinesterase-based biosensor, the MPDE biosensor can be potentially reused and is suitable for continuous monitoring. PMID:19926466

Abstract in spanish Introducción. Por ser los plaguicidas anticolinesterásicos una causa importante de intoxicación y de muerte por intoxicación en los países en vía de desarrollo, el Instituto Nacional de Salud implementó el Programa de Vigilancia Epidemiológica de Organofosforados y Carbamatos, del cual, este informe corresponde al período 2002-2005. Objetivo. Determinar la actividad de la acetilcolinesterasa en participantes con riesgo de exposición a plaguicidas organofosforado (more) s y carbamatos, e identificar los plaguicidas más utilizados en el área estudiada. Materiales y métodos. Es un estudio descriptivo de información reportada al Programa de Vigilancia Epidemiológica de Organofosforados y Carbamatos por once departamentos colombianos, los cuales realizaron la determinación de acetilcolinesterasa con el equipo Lovibond. Resultados. Participaron 28.303 personas con riesgo de exposición a plaguicidas; 81,4% eran hombres. El 9,3% de las determinaciones analíticas fueron anormales, con una prevalencia de anormalidad entre los hombres de 9,9% y de 7,0% en las mujeres. Presentaron mayor prevalencia de valores anormales los grupos de edad de 18 a 25 años (12,3%) y de 0 a 5 años (10,7%), y los oficios de jornalero (27,0%) y servicios generales del campo (26,1%). De los 975 participantes, en el departamento del Meta, 80% de los participantes presentaron niveles anormales de actividad de la enzima. Los plaguicidas más reportados fueron los organofosforados (39,7%) y carbamatos (16,6%). Conclusión. El incremento en la prevalencia de valores anormales de la acetilcolinesterasa y el riesgo de exposición infantil, hacen necesario disminuir el uso y la comercialización de plaguicidas de alto riesgo, y utilizar métodos menos tóxicos para el control de plagas. Abstract in english Introduction. Due to the importance of acetylcholinesterase inhibiting chemicals as pesticides in developing countries, the Instituto Nacional de Salud in Colombia designed the organophosphate and carbamate epidemiological surveillance program for the period 2002-2005. Objective. The acetylcholinesterase activity was determined in study participants with a history of organophosphate and carbamate exposure and the most commonly used pesticides were identified in each study (more) area. Materials and methods. The information was compiled from reports sent to the Instituto Nacional de Salud organophosphate and carbamate epidemiological surveillance program from each of 11 provinces in Colombia. The analytical determination of the biomarker was performed by acetylcholinestare activity determined with the Lovibond field equipment. Results. A total of 28,303 people were designated as having risk of exposure to pesticides. Most were men (81.4%). Abnormal determinations averaged 9.3% (9.9% in men and 7.0% in women). The 18-25 year old age group showed the highest prevalence of abnormal results (12.3%), followed by the group of 0-5 year olds (10.7%). The highest prevalence of abnormal acetylcholinesterase activity was in farm workers (27.0%), followed by general outdoor activities (26.1%). In the province of Meta, 80% of participants showed abnormal values of enzyme activity. The most commonly used pesticides were organophosphates (39.7%) and carbamates (16.6%). Conclusion. The increase in the prevalence of abnormal values of acetylcholinesterase activity and the risk of exposure to pesticides in children necessitates a lowering of use and commercialization of high risk pesticides, and a need for developing safer methods for pest management.

We report on the development and validation under ISO 17025 criteria of a multi-residue confirmatory method to identify and quantify 17 widely chemically different pesticides (insecticides: Carbofuran, Methiocarb, Pirimicarb, Dimethoate, Fipronil, Imidacloprid; herbicides: Amidosulfuron, Rimsulfuron...

Pesticides are among the most widely used chemicals in the world. Because of the widespread use of agricultural chemicals in food production, people are exposed to low levels of pesticide residues through their diets. Scientists do not yet have a total understanding of the health effects of these pesticide residues. This work aims to determine differences in terms of pesticide residue content in Portuguese strawberries grown using different agriculture practices. The Quick, Easy, Cheap, Effective, Rugged, and Safe sample preparation method was conducted and shown to have good performance for multiclass pesticides extraction in strawberries. The screening of 25 pesticides residue was performed by gas chromatography-tandem mass spectrometry. In quantitative validation, acceptable performances were achieved with recoveries of 70-120 and organic and integrated pest management (IPM) practices harvested in 2009-2010. The results showed the presence of fludioxonil, bifenthrin, mepanipyrim, tolylfluanid, cyprodinil, tetraconazole, and malathion when using IPM below the maximum residue levels. PMID:22562348

Dormant spray application of pesticides to almond and other stone fruit orchards is the main source of diazinon during the winter in California's central valley. Understanding the pesticide transport and the tradeoffs associated with the various management practices is greatly facilitated by the use of physically-based contaminant transport models. In this study, performance of Joyce's et al. (2008) pesticide transport model was evaluated using experimental data collected from two ground treatments such as resident vegetation and bare soil. The model simulation results obtained in calibration and validation process were analyzed for pesticide concentration and total load. The pesticide transport model accurately predicted the pesticide concentrations and total load in the runoff from bare ...

In order to estimate the risk op groundwater contamination by surface applied pesticides, the fate of pesticides in the unsaturated zone needs to be evaluated. Process models that describe relevant processes such as transport of dissolved pesticides, sorption, degradation and root uptake, in combination with water and heat fluxes in the soil have been developed and used for regulatory purposes. Regional assessments are required to indentify regions with higher risks of groundwater contamination. A major problem for the application of process models for a regional, EU-member state, or EU-scale assessment of pesticide leaching risk is the availability of regional databases of input parameters and boundary conditions that are required to run these models. Therefore, procedures that can assess pesticide leaching risk based on databases with regional coverage are required. In this presentation, we compare two different approaches for a regional estimation of pesticide leaching risk to groundwater in Germany. The first method uses an indicator approach to evaluate the risk of pesticide leaching as a function of a number of categorized soil, climate and pesticide properties. The result is a map of categorized risks. In the second approach, a metamodel is used to estimate the leached pesticide concentrations based on nation-wide available data of yearly average precipitation, temperature, soil organic matter content, soil texture, and pesticide parameters. The metamodel represents a synthesis of relations between climate, soil, and pesticide properties on one hand and leaching concentrations that are simulated by a more detailed process model on the other hand. The obtained maps of leaching risks and leaching concentrations were compared with the locations of anomynized pesticide findings in groundwater. The use of databases of pesticide findings in groundwater for the validation of leaching risks assessments is discussed.

Although it is relatively easy to find chemiluminescent (CL) molecules working on the field of direct liquid phase (especially employing strong oxidants), the molecules found as chemiluminescent are normally very weak CL compounds for developing suitable analytical CL-procedures. Therefore, it is mandatory to develop new strategies to enhance in a simple way the native chemiluminescence of such a compounds, and even to increase the number of compounds to be determined by direct chemiluminescence. Photoinduced chemiluminescence (Ph-CL) results in a simple and easily on-line accessible strategy to solve these disadvantages. In the present paper, molecular connectivity, a topological method which allows an unique mathematical characterization of molecular structures by the so-named topological descriptors and their correlation with physical, chemical and biological properties of molecules was applied to predict the Ph-CL in liquid phase. Molecular connectivity calculations and discriminant analysis was applied to 72 pesticides for which either a Ph-CL or non Ph-CL behaviour was observed in an experimental screening. The screening test is based on the on-line photodegradation of pesticides by using an automated multicommutation based flow asssembly provided with a photoreactor consisting of 150 cm x 0.8mm PTFE tubing helically coiled around a 20 W low-pressure mercury lamp. Photodegraded pesticides are detected by direct chemiluminescence of the resulting photo-fragments and their subsequent reaction with potassium permanganate in sulfuric acid medium as oxidant. The screening comprised pesticides with different molecular structures and relevant members of the most important families of pesticides were tested (oxime carbamates, sulfonylcarbamates, thiocarbamates, 1,3,5-triazines, organophosphorous, hydroxybenzonitrile, sulfonylureas, phosphonic acid derivatives, imidazolinones, carboxamides, aryloxyalkanoic acids, 1,2,4-triazinones, etc.). The theoretical predictions agree with the empirical results obtained by means of the screening test performed in the multicommutation flow-assembly. PMID:19071628

Solid phase extraction. SPE. using C{sub 1}8 bonded silica cartridges for trace amounts determination of carbaryl, propoxur, thiram, propham and methiocarb in water samples was studied and the breakthrough volume of the cartridges was established. The high enrichment factor and large injection volume admissible in the isocratic reverse-phase HPLC system allows pesticides determination with UV detection at 22o nm even at a concentration lower than 0.05 mug/L. Purified tap natural and underground water samples were spiked with carbamate pesticides in the concentration range 0.16-16.0 mug/L. Large volumes of samples (up to 2L) were passed through available C{sub 1}8, cartridges and eluted with acetonitrile. The preconcentrated samples were analyzed by HPLC using a Spherisorb ODS column with a 42.58 acetonitrile-water mobile phase. From replicate samples, recovery for the pesticides ranged from 79.0 to 103.7% except for thiran which is not retained. Tehe relative standard deviation (n=4 at 0.16 to 1.61 mug/L concetration level) range from 1.1 to 6.8%. (Author) 14 refs.

Acetylcholinesterase (ChE) sensor based on Prussian blue (PB) modified electrode was developed and tested for the detection of organophosphorus and carbamic pesticides. The signal of the sensor was generated in PB mediated oxidation of thiocholine recorded at +200 mv in DC mode. ChE from electric eel was immobilized by cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) on the surface of screen-printed carbon electrode covered with PB and Nafion. The content of the surface layer (specific enzyme activity, Nafion and BSA amounts) was optimized to establish high and reliable response toward the substrate and ChE inhibitors. The ChE/PB sensor makes it possible to detect Aldicarb, Paraoxon and Parathion-Methyl with limits of detection 30, 10 and 5 ppb, respectively (incubation 10 min). The feasibility of practical application of the ChE/PB sensor developed for the monitoring of degradation of the pesticides in wine fermentation was shown. To diminish matrix interferences, the electrolysis of the grape juice with Al anode and evaporation of ethanol were suggested, however the procedures decrease the sensitivity of pesticide detection and stability of the sample tested. PMID:16163484

In 2007, samples of treated effluent were collected at point of discharge to the environment from 39 wastewater treatment plants (WWTPs) located across Victoria, Australia grouped by treatment type. Sample genotoxicity was assessed with a high-throughput luminescent umu test method using Salmonella typhimurium TL210 strain, with and without addition of a commercially available metabolic activation system. Samples were also screened using a gas chromatographic-mass spectrometric mass-structure database recognition method. A genotoxic response was observed in half of the samples tested without metabolic activation system (tyre leachates (e.g. 2(3H)-benzothiazolone), antioxidants, flame retardants (e.g. tris(2-chloroethyl)phosphate), insect repellents (e.g. diethyltoluamide), stimulants (e.g. caffeine) and anticonvulsants (e.g. carbamazepine). Of the 451 pesticides screened, carbamate insecticides (e.g. bendiocarb, propoxur), plant growth regulators (e.g. propham) and herbicides (e.g. atrazine, metolachlor, simazine) were amongst the compounds observed. PMID:22766865

A fast and efficient method for the determination of trace level of carbamate pesticides using a lower-density-than-water solvent for ultrasound-assisted emulsification microextraction coupled to on-column derivatization and analysis by GC-MS has been developed and studied. In this approach, a soft plastic Pasteur pipette was employed as a convenient extraction device. Fifty microliters of extraction solvent, of lower density than water, was injected into the sample solution held in the pipette. The latter was immediately immersed in an ultrasound water bath to form an emulsion. After 2min extraction, the emulsion was fractionated into two layers by centrifugation. The upper layer (organic extract) could be collected conveniently by squeezing the bulb of the pipette, now held upside down, ...

Enzyme spectrophotometric assays based on acetylcholinesterase (AChE) inhibition were used in combination with Artificial Neural Network (ANN) chemometric analysis for the resolution of pesticides mixtures of chlorpyriphos, dichlorvos and carbofuran. Electric eel (EE) AChE and the recombinant B394-AChE from Drosophila melanogaster were selected due to their different sensitivities to insecticides. These enzymes were used in association with phosphotriesterase (PTE), an enzyme allowing to discriminate between organophosphate and carbamate insecticides. The combined response of three enzymes systems composed of EE-AChE, EE-AChE+PTE, and B394-AChE+PTE was modelled by means of ANN. Specifically, an ANN was constructed where the structure providing the best modelling was a single hidden layer c...

Benthiavalicarb-isopropyl, a novel member of the amino acid amide carbamate group of fungicides, is effective against all Oomycete fungal plant pathogens except Pythium spp. Our results demonstrate that this fungicide effectively controls potato and tomato late blight caused by metalaxyl-sensitive and -resistant strains of Phytophthora infestans. Experiments in vitro demonstrated that benthiavalicarb-isopropyl was ineffective in stopping the discharge of zoospores from zoosporangia and suppressing their motility; but strongly inhibited mycelial growth, sporulation, and the germination of sporangia and cystospores. Experiments in a greenhouse showed that benthiavalicarb-isopropyl has not only a strong preventive, but also a curative effect; its translaminar properties are effective along with its rainfastness and residual activity. In field trials, it was effective in controlling tomato and potato late blight at 25–75 g a.i./ha. © Pesticide Science Society of Japan   

Fipronil is a relatively new insecticide that controls a broad spectrum of insects at low field application rates. It is a “new generation” insecticide because its mode of action, interference with the normal function of ?-aminobutyric acid (GABA)-gated channels, differs from the classical insecticides, such as organophosphates and carbamates, to which some insects have developed resistance. Fipronil is extensively used throughout the world and numerous studies have evaluated its toxicity and environmental fate. However, a concise review summarizing and combining the recent scientific findings available in the scientific literature is lacking even though the pesticide has been found to be highly toxic to some aquatic organisms. Thus, this document evaluates, summarizes, and combines important toxicological and environmental fate information from recent scientific articles and other literature to produce a detailed review of fipronil.   

We report the presence of organophosphorus and carbamate residues in 24 surface water samples and five ground water samples from Pirgacha Thana, Rangpur district, Bangladesh using high-performance liquid chromatography. A number of samples of surface water from paddy fields were found to contain chlorpyriphos, carbofuran and carbaryl at concentrations ranging from 0â??1.189, 0â??3.395 and 0â??0.163 μg/L, respectively. Surface water from the lakes had chlorpyriphos, carbofuran and carbaryl at concentrations ranging from 0.544â??0.895, 0.949â??1.671 and 0â??0.195 μg/L, respectively. This result indicates that the general public living in the area of Rangpur is at high risk of pesticide exposure from contaminated waters in the environment.

The objective of this study was to investigate the response of acetylcholinesterase (AChE) activities in Clarias gariepinus in response to Organophosphates (Ops) and carbamate exposure. The AChE activities were determined in plasma, and eye and brain homogenates of unexposed and exposed fish using Ellman?s method and 5,5?-dithiobis-2-nitrobenzoic acid (DTNB) chromophore. The baseline AChE activities in plasma, eyes and brain tissues in unexposed fish were comparable between males and females (P?>?0.05). Concentrations of pesticides that inhibited 50% (IC50) of AChE activities in brain homogenates following in vitro exposures were 0.003, 0.03, 0.15, 190, 0.2, 0.003 and 0.002??M for carbaryl, chlorfenvinphos, diazinon, dimethoate, fenitrothion, pirimiphosmethyl and profenofos, respectively. ...

Tibial dyschondroplasia (TD) is a major poultry leg problem, the natural etiology of which is unknown. Certain dithiocarbamate pesticides such as tetramethyl thiuram disulfide (thiram) have been shown to induce the disease in chickens. Because many different carbamate and thiocarbamate chemicals are used in a number of agricultural, industrial, and household applications, the objective of this study was to determine whether all chemicals of these categories induce TD and whether there is a concentration-dependent relationship between the ingestion of these chemicals and the incidences and the severity of the disease. Week-old broiler chicks were fed diets containing thiram or other assorted carbamate and thiocarbamate pesticides mixed in feed for 24-48 hr between ages 8 and 10 days. The birds were killed on day 15 and the proximal tibial and tarsometatarsal growth plates were evaluated for the presence and severity of TD lesions. TD was distinguished by broadening of growth plates; upon histologic exam chondrocytes appeared to be shrunken and dead. When compared by including equimolar concentrations of these chemicals in the feed, the dithiocarbamates with more than two sulfide groups, such as disulfiram, ferbam, thiram, and ziram were potent inducers of TD, whereas those with two sulfides to no sulfide group appeared ineffective at inducing TD. Both thiram and ferbam also reduced the bird's body weights. Thiram increased the incidence and the severity of the disease, denoted by TD index, in a dose-dependent manner. These results suggest that inadvertent contamination of feed or litter with some of these or similar chemicals may cause leg problems in poultry. PMID:17626489

Abstract in portuguese Um método espectrofotométrico simples, baseado na reação de um pesticida carbamato, carbofurano (2,3-diidro,2,2-dimetil-7-benzofuranil metil carbamato), com o sal diazônio da p-aminoacetofenona (PAAPD) sob condições alcalinas é descrito. O corante laranja formado pela reação do pesticida com o PAAPD foi medido em 460 nm. A lei de Beer é obedecida no intervalo de concentração de 0,1 a 1,2 µg mL-1 de carbofurano em uma solução final de 25 mL. A absortividade (more) molar e sensitividade de Sandell encontradas foram 1,2x10(5) L mol-1 cm-1 e 0,0014 mg cm-2, respectivamente. As condições ótimas de reação e outras condições analíticas foram avaliadas. O efeito de íons interferentes na determinação de carbofurano é descrito. O método foi aplicado com sucesso na determinação de carbofurano em arroz, germe de trigo e várias amostras biológicas e ambientais. Os resultados obtidos foram comparados com outros métodos espectrofotométricos e cromatográficos estabelecidos para carbofurano. Abstract in english A simple spectrophotometric method based on the coupling of a carbamate pesticide, carbofuran (2, 3-dihydro, 2, 2-dimethyl-7-benzofuranyl methyl carbamate) with diazotized p-aminoacetophenone (DPAAP) under alkaline condition is described. The orange dye formed by coupling of the pesticide with DPAAP was measured at 460 nm. Beer's law is obeyed over the concentration range of 0.1 to 1.2 µg mL-1 of carbofuran in a final solution of 25 mL. Molar absorptivity and Sandell's s (more) ensitivity were found to be 1.2x10(5) L mol-1 cm-1 and 0.0014 µg cm-2 respectively. The optimum reaction condition and other analytical conditions were evaluated. The effect of interfering ions on the determination of carbofuran is described. The method has been successfully applied to the determination of carbofuran in rice, wheat and various environmental and biological samples. The results obtained were compared with other spectrophotometric and chromatographic methods reported for carbofuran.

Abstract in english This paper presents a practical and rapid method which was validated for simultaneous quantification and confirmation of 29 pesticides in fruits and vegetables using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted following the method known as QuEChERS. Using the developed chromatographic conditions, the pesticides can be separated in less than 9 min. Two multiple reaction monitoring (MRM) assays were used for each (more) pesticide. Four representative matrices (lettuce, tomato, apple and grapes) were selected to investigate the effect in recoveries and precision. Typical recoveries ranged from 70-120%, with relative standard deviation (RSDs) lower than 20%.

Despite considerable increased pesticide use over the past decades, little research has been done into their fate and effects in surface waters in tropical regions. In the present review, possible differences in response between temperate and tropical freshwaters to pesticide stress are discussed. Three underlying mechanisms for these differences are distinguished: (1) climate related parameters, (2) ecosystem sensitivity, and (3) agricultural practices. Pesticide dissipation rates and vulnerability of freshwaters appear not to be consistently higher or lower in tropical regions compared to their temperate counterparts. However, differences in fate and effects may occur for individual pesticides and taxa. Furthermore, intensive agricultural practices in tropical countries lead to a higher input of pesticides and spread of contamination over watersheds. Field studies in tropical farms on pesticide fate in the enclosed and surrounding waterways are recommended, which should ultimately lead to the development of surface water scenarios for tropical countries like developed by the Forum for the co-ordination of pesticide fate models and their use for temperate regions. Future tropical effect assessment studies should evaluate whether specific tropical taxa, not represented by the current standard test species in use, are at risk. If so, tropical model ecosystem studies evaluating pesticide concentration ranges need to be conducted to validate whether selected surrogate indigenous test species are representative for local tropical freshwater ecosystems. PMID:19705279

The toxicity of carbaryl, chlorpyrifos, dimethoate and profenofos to the freshwater shrimp, Paratya australiensis was assessed by measuring acetylcholinesterase (AChE) inhibition after 96h exposures. Shrimp exposed to these pesticides exhibited significant AChE inhibition, with mortality in shrimp corresponding to 70-90% AChE inhibition. The sensitivity of P. australiensis to the four pesticides based on AChE inhibition can be given as chlorpyrifos > profenofos > carbaryl > dimethoate. Recovery of AChE activity was followed in shrimp after 96 h exposures to carbaryl, chlorpyrifos and dimethoate. Recovery after exposure to the carbamate pesticide carbaryl was more rapid than for the two organophosphorus pesticides, chlorpyrifos and dimethoate. The slow recovery of depressed AChE activity may mean that affected organisms in the natural system are unable to sustain physical activities such as searching for food or eluding predators. To investigate the ecological significance of AChE inhibition, chemotaxis behaviour was assessed in shrimp exposed to profenofos for 24h. Abnormal chemotaxis behaviour in the exposed shrimp was observed at concentrations representing 30-50% AChE inhibition. A clear relationship existed between the depression of AChE activity and observed chemotaxis responses, such as approaching and grasping the chemoattractant source. These results suggest that in vivo toxicity tests based on this specific biomarker are sensitive and present advantages over conventional acute tests based on mortality. Behavioural studies of test organisms conducted in conjunction with measurement of AChE inhibition will provide data to clarify the toxic effects caused by sublethal chemical concentrations of anti-cholinesterase compounds. PMID:20701973

Daphnia magna is a key invertebrate in the freshwater environment and is used widely as a model in ecotoxicological measurements and risk assessment. Understanding the genomic responses of D. magna to chemical challenges will be of value to regulatory authorities worldwide. Here we exposed D. magna to the insecticide methomyl and the herbicide propanil to compare phenotypic effects with changes in mRNA expression levels. Both pesticides are found in drainage ditches and surface water bodies standing adjacent to crops. Methomyl, a carbamate insecticide widely used in agriculture, inhibits acetylcholinesterase, a key enzyme in nerve transmission. Propanil, an acetanilide herbicide, is used to control grass and broad-leaf weeds. The phenotypic effects of single doses of each chemical were evaluated using a standard immobilisation assay. Immobilisation was linked to global mRNA expression levels using the previously estimated 48h-EC(1)s, followed by hybridization to a cDNA microarray with more than 13,000 redundant cDNA clones representing >5000 unique genes. Following exposure to methomyl and propanil, differential expression was found for 624 and 551 cDNAs, respectively (one-way ANOVA with Bonferroni correction, Ptest chemicals. Both pesticides promoted transcriptional changes in energy metabolism (e.g., mitochondrial proteins, ATP synthesis-related proteins), moulting (e.g., chitin-binding proteins, cuticular proteins) and protein biosynthesis (e.g., ribosomal proteins, transcription factors). Methomyl induced the transcription of genes involved in specific processes such as ion homeostasis and xenobiotic metabolism. Propanil highly promoted haemoglobin synthesis and up-regulated genes specifically related to defence mechanisms (e.g., innate immunity response systems) and neuronal pathways. Pesticide-specific toxic responses were found but there is little evidence for transcriptional responses purely restricted to genes associated with the pesticide target site or mechanism of toxicity. PMID:20092900

Abstract in spanish Introducción. En 2005 el Sistema de Vigilancia en Salud Pública encontró que el departamento del Putumayo es la región con mayor incidencia de intoxicaciones por plaguicidas en Colombia. Objetivo. Establecer la exposición a plaguicidas organofosforados y carbamatos en la población agrícola mediante la determinación de los niveles de acetilcolinesterasa en el departamento de Putumayo, utilizando el método de Michel. Materiales y métodos. Se realizó un estudio tr (more) ansversal en 204 trabajadores ocupacionalmente expuestos, en cuatro municipios del departamento de Putumayo. Se aplicó una encuesta para recolectar información y se tomó una muestra de sangre para la determinación de la acetilcolinesterasa. Se llevó a cabo el análisis simple de las variables y se exploraron posibles asociaciones. Un grupo de trabajadores fueron capacitados con la metodología SARAR (una estrategia educacional participativa que significa: S: seguridad, A: asociación, R: reacción, A: actualización y R: responsabilidad) sobre el uso y el manejo de plaguicidas. Resultados. Se estableció que el tiempo promedio de exposición fue de nueve años. El 75,2% manifestó emplear plaguicidas extremadamente tóxicos y el 13,0% altamente tóxicos. En promedio refirieron aplicar plaguicidas 7,3 horas al día. El 9,8% usaban plaguicidas organoclorados. En cuanto a la actividad de la enzima acetilcolinesterasa, 17,6% presentaban inhibición. Conclusión. Este trabajo permitió tener una dimensión real del problema de los plaguicidas en el Putumayo y utilizarla para hacer una intervención educativa sobre los trabajadores y sus familias, con la metodología SARAR. Abstract in english Introduction. In 2005, the Sistema de Vigilancia en Salud Pública, the governmental agency responsible for monitoring public health, found that Putumayo Province has the highest incidence of poisoning by pesticides in Colombia. Objective. Exposure to organophosphorus and carbamate pesticides and carbamates was established in the agricultural population of Putumayo by determining acetylcholinesterase levels. Materials and methods. A cross-sectional survey was made in 204 (more) occupationally exposed workers in four municipalities of Putumayo. A questionnaire was administered to collect subject information; a blood sample was taken for acetylcholinesterase determination by Michel?s method. A straightforward analysis of the variables and possible associations were explored. A group of workers was enabled with SARAR (a participative educational strategy that means: S: safety, A: association, R: reaction, A: actualization and R: responsability)methodology for use and handling of pesticides. Results. The average time of exposure was nine years. Seventy-five percent declared using extremely toxic pesticides and 13% highly toxic. On average, they applied pesticides 7.3 hours/day. Nearly 10% used organochloride pesticides. Furthermore, 17.6% demonstrated inhibition of the enzyme acetylcholinesterase. Conclusion. A realistic scale of the pesticide use problem in humans was obtained; and the data effectively recommend an educatiional intervention for the workers and their families with SARAR methodology.

A novel, proteomics based method was developed for the detection, quantification, and categorization of serum butyrylcholinesterase (BChE) inhibitors, including organophosphates (OPs) and carbamates (CBs). This method was based on the MALDI-TOF-MS analysis of the trypsin generated BChE active site peptide (191-SVTLFGESAGAASVSLHLLSPR-212) previously modified by reaction with an OP or CB. The ionization efficiency of OP modified active site peptides by MALDI was greatly improved by adding diammonium citrate to the MALDI matrix, which made the quantification of OP exposure feasible. Excellent linearity (r2 > 0.98) between the normalized abundance ratios (NARs) and OP concentrations or logarithm of carbaryl concentration was obtained. The accuracy of the developed assay was evaluated by comparison of IC50 and IC100 values from the assay with those determined by the Ellman method. Results from this method were comparable with those from the Ellman method. The advantage of the assay was that both the origin and the extent of pesticide exposure can be determined in one analysis. Our MALDI method can provide critical evidence for the pesticide exposure at low BChE inhibition levels even down to 3%, not available with the Ellman method. PMID:17223355

Carboxylesterases (CES, EC 3.1.1.1) are members of a superfamily of serine hydrolases that hydrolyze ester, amide, and carbamate bonds. Several different CES genes exist in mammalian species with evidence of multiple gene duplication events occurring throughout evolutionary history. There are five CES genes reported in the Human Genome Organization database, although CES1 and CES2 are the two best characterized human genes. An emerging picture of the CES family suggests that these enzymes have dual roles in the metabolism of xenobiotic and endobiotic compounds. Pesticides, such as the pyrethroids, are important xenobiotic substrates that are metabolized by CES, whereas cholesteryl esters, triacylglycerols, and 2-arachidonoylglycerol are examples of endobiotics known to be substrates for CES. Functional studies using selective chemical inhibitors, siRNA, and gene knockout models are providing valuable insights into the physiological functions of CES, and suggest that CES may be a novel target for the treatment of diseases such as diabetes and atherosclerosis. This review will examine the known physiological functions of CES, the interactions between xenobiotics (primarily pesticides) and lipids that occur with CES enzymes, and where possible the implications that these findings may have in terms of health and disease.   

Abstract in spanish Debido al alto grado de contaminación por plaguicidas de productos agrícolas y al alto costo que implica su detección se consideró importante optimizar el método de escrutinio de inhibición de colinesterasas humanas en presencia de extractos vegetales. Se demostró que las suspensiones de glóbulos rojos y plasma son estables al menos por tres meses si se mantienen entre 4 y 8 °C. El reactivo de color es estable por al menos dos años y medio en refrigeración y lo (more) s sustratos de ambas colinesterasas son estables congelados al menos por dos años. La mezcla del extracto vegetal y los glóbulos rojos o plasma debe incubarse 90 minutos a 37 °C para determinar los porcentajes de inhibición enzimática. Se determinó que los porcentajes de inhibición superiores a 16% en la plasmática y a 21% en la eritrocítica indican presencia de plaguicida en los vegetales. Este método de screening optimizado para detectar la presencia de carbamatos y organofosforados tiene ventaja sobre otros por su bajo costo, facilidad y rapidez de análisis sin requerir de equipo costoso y poco versátil. Esta metodología no cuantifica ni identifica el plaguicida presente pero permite diferenciar entre organofosforados y carbamatos si el periodo de incubación del vegetal con eritrocitos o plasma se prolonga por 24 horas a 20-25 °C. Abstract in english Optimization of the screening method of inhibition of human cholinesterases is considered important because of the high contamination rate of agricultural products with pesticides and its high detection cost. It has been demonstrated that erythrocytes and plasma are stable at least for three months at 4-8 °C. The colour reaction reagent is stable for at least two and a half years at 4-8 °C and the substrate for both cholinesterases is stable when frozen, at least for tw (more) o years. The solution of vegetable extract and erythrocytes or plasma must be incubated 90 minutes at 37 °C in order to determine the percentages of enzymatic inhibition. It was established that inhibition percentages higher than 16% for the plasmatic solution, and 21% for the erythrocytic solution mean that pesticide is present in vegetables. The advantages of this optimized screening method for the detection of carbamates and organophosphates in vegetables are its low cost and its easy and quick analysis without the need of expensive equipment. This method does not quantify or identify the pesticide, but rather it differentiates organophosphates from carbamates if the incubation time of the vegetable extract with erythrocytes or plasma is maintained at 20- 25 °C for 24 hours.

Simulation of pesticide volatilization from plant and soil surfaces as an integral component of pesticide fate models is of utmost importance, especially as part of the PEC (predicted environmental concentrations) models used in the registration procedures for pesticides. Experimentally determined volatilization rates at different scales were compared to model predictions to improve recent approaches included in European registration models. To assess the influence of crucial factors affecting volatilization under well-defined conditions, a laboratory chamber was set-up and validated. Aerodynamic conditions were adjusted to fulfill the requirements of the German guideline on assessing pesticide volatilization for registration purposes. At the semi-field scale, volatilization rates were determined in a wind-tunnel study after soil surface application of pesticides to gleyic cambisol. The following descending order of cumulative volatilization was observed: chlorpyrifos > parathion-methyl > terbuthylazine > fenpropimorph. Parameterization of the models PEARL (pesticide emission assessment at regional and local scales) and PELMO (pesticide leaching model) was performed to mirror the experimental boundary conditions. (orig.)

The applicability of multi-residue analytical method for 496 pesticides (including metabolites) in frozen gyoza dumplings was verified. This method involved extraction using aqueous acetonitrile (around 70% of acetonitrile content) followed by cleanup using octadecylsilyl (ODS) and primary secondary amine (PSA) mini-column solid-phase extraction (SPE). The target compounds were determined by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Validation tests were performed on frozen gyoza dumplings fortified at 0.01 and 0.10 ?g/g in accordance with the guideline issued by the Japanese Ministry of Health, Labour and Welfare. Among the 496 pesticides tested, 378 pesticides were found to conform to the guideline when the solvent standard was used, and 432 pesticides conformed when the matrix-matched standard was used, respectively. The limits of quantitation (S/N?10) were set at 0.01 ?g/g for all, except 20 of the pesticides that were tested. Although no significant matrix effects were observed for most of the pesticides, the use of the matrix-matched standard was preferable to the solvent standard for accurate quantitation. The method was applied to 11 commercial samples, and 14 different pesticides were detected from 8 samples at concentrations ranging from trace levels (<0.01 ?g/g) to 0.11 ?g/g.   

The distribution of pyrethroid and phenylpyrazole pesticides in the water environment has raised public concerns because of their potential risks to ecosystem and human health. However, co-extraction of emulsifier type compounds (by liquid-liquid extraction, LLE) present in environmental samples can present a challenge for quantifying typically low concentrations of pesticides. Several methods were evaluated for breaking emulsions in problematic environmental surface water samples extracted by LLE using methylene chloride. Target pesticides included 11 typical pyrethroid and phenylpyrazole pesticides commonly used in agricultural and landscape insect pest control. The most effective method was selected for validation in fortification studies with GC-ECD analysis. The average recoveries of spiked pyrethroid and phenylpyrazole pesticides were 88.2-123.4% for water samples with moderate emulsions and 93.0-117.4% for water samples with severe emulsions. Recoveries of the pesticides ranged 81.0-126.4% (water samples with moderate emulsions) and 95.9-110.6% (water samples with severe emulsions) for lowest fortification level (5-20 ngL(-1)), 88.2-123.4% (water samples with moderate emulsions) and 93.0-117.4% (water samples with severe emulsions) for middle fortification level (10-40 ngL(-1)), and 90.2-119.9% (water samples with moderate emulsions) and 91.2-105.9% (water samples with severe emulsions) for highest fortification level (50-200 ngL(-1)). Relative standard deviations of pesticide recoveries were usually emulsion-prone surface water samples. PMID:20832073

Pesticides are widely used in rice cultivation, often resulting in detection of their residues in rice grains. So far, no analytical method has been available for the simultaneous determination of most rice pesticides in rice grains. This paper reports the development and validation of such a method for the determination of eight rice pesticides (penoxsulam tricyclazole, propanil, azoxystrobin, molinate, profoxydim, cyhalofop-butyl, deltamethrin) and 3,4-dichloroaniline, the main metabolite of propanil. Pesticide extraction and clean-up was performed by an optimized matrix solid-phase dispersion (MSPD) protocol on neutral alumina (5?g) using acetonitrile as the elution solvent. Samples were analyzed in a high-performance liquid chromatography?diode array detection (HPLC-DAD) system. Pestic...

Aldicarb, 2-methyl-2-(methylthio)propionaldehyde-O-methylcarbamoyloxime, is an oxime carbamate insecticide manufactured by the Union Carbide Corporation and sold under the trade name Temik. It is a soil-applied systemic pesticide used against certain insects, mites, and nematodes, and is applied below the soil surface for absorption by plant roots. It is generally applied to the soil in the form of 5, 10, or 15% granules, and soil moisture is essential for the release of the toxicant. Uptake by plants is rapid. Aldicarb is currently registered for use on cotton, sugar beets, sugar cane (Louisiana only), potatoes, sweet potatoes, peanuts, oranges, pecans (Southeast only), dry beans, soybeans, and ornamental plants. Home and garden use is not permitted. Discovery of aldicarb and its oxidative sulfoxide and sulfone metabolites in well or ground water in Florida, Wisconsin, and New York, and accidental poisonings from ingesting contaminated watermelons and cucumbers in the South and West have spurred interest and concern about this pesticide. The primary mechanism of toxic action of aldicarb is cholinesterase inhibition. However, unlike the relatively irreversible anticholinesterase activity of the organophosphate pesticides, the carbamylation process which produces the anti-AChE action is quickly reversible. Aldicarb is readily absorbed through both the gut and the skin, but is rapidly metabolized and excreted in the urine almost completely within 24 hr. Although it is acutely toxic to humans and laboratory animals, aldicarb is not known to be carcinogenic, teratogenic, conclusively mutagenic, or to produce other long-term adverse health effects. In cases of accidental poisoning, the cholinergic symptoms have generally subsided within 6 hr, with no side effects or complications.

Objective: The impact of long term exposure to cholinesterase (ChE)-inhibiting organophosphate (OP) and carbamate (C) pesticides on the respiratory health of agricultural workers in India was investigated. Methods: Three hundred and seventy-six nonsmoking agricultural workers (median age 41 yr) from eastern India who sprayed OP and C pesticides in the field and 348 age- and sex-matched control subjects with non-agricultural occupations from the same locality were enrolled. Prevalence of respiratory symptoms was obtained by questionnaire survey, and pulmonary function tests were carried out by spirometry. Chronic obstructive pulmonary disease (COPD) was diagnosed by the Global Obstructive Lung Disease (GOLD) criteria, and erythrocyte acetylcholinesterase (AChE) was measured by the Ellman method. Results: Agricultural workers had greater prevalences of upper and lower respiratory symptoms, and appreciable reduction in spirometric measurements. Overall, lung function reduction was noted in 48.9% of agricultural workers compared with 22.7% of control, and a restrictive type of deficit was predominant. COPD was diagnosed in 10.9% of agricultural workers compared with 3.4% of controls (p<0.05 in ?2 test), and the severity of the disease was greater in agricultural workers. Red blood cell (RBC) AChE was lowered by 34.2% in agricultural workers, and the fall in AChE level was positively associated with respiratory symptoms, lung function decrement and COPD after controlling for education and income as potential confounders. Conclusions: Long-term exposure to cholinesterase-inhibiting agricultural pesticides currently in use in India is associated with a reduction in lung function, COPD and a rise in respiratory symptoms.   

A method for the determination of pesticide residues in water and sediment was developed using the QuEChERS method followed by gas chromatography – mass spectrometry. The method was validated in terms of accuracy, specificity, linearity, detection and quantification limits. The recovery percentages ...

An Euler atmospheric transport model (Canadian Model for Environmental Transport of Organochlorine Pesticides, CanMETOP) was applied and validated to estimate polycyclic aromatic hydrocarbon (PAH) ambient air concentrations at ground level in China based on a high-resolution emission inventory. The ...

The objective of this work was to evaluate the EPA’s proposed Test Plan for the validation testing of pesticide spray drift reduction technologies (DRTs) for row and field crops, focusing on the evaluation of ground application systems using the low-speed wind tunnel protocols and processing the dat...

Pesticides in stream flow at the outlet of a 142ha catchment in Eastern England (Col- worth, Bedfordshire), have been monitored since October 1999. About 50% of the total catchment is directly controlled within one farm and a rotation of wheat, oil seed rape, grass, linseed, beans and peas is grown. The data from this catchment are being used to investigate the performance of the USDA SWAT contaminant transport pack- age at the catchment scale. Three years of stream flow and climate data are available with a useful set of pesticide application and detection data. Following calibration and validation of the hydrology of the catchment, pesticide modelling was carried out for tebuconazole, terbutryn, and terbuthylazine. This paper reports on the results of a sen- sitivity analysis of the model, and the final calibrated pesticide component. Analysis of the results obtained show that the timing and decay of predicted pesticide concen- trations are correct. It is therefore recommended that SWAT can be used as a tool to understand pesticide behaviour at the catchment scale.

Short-term pollution events via runoff are typical of streams in agricultural areas. Existing runoff models that simulate pesticide loss from agricultural fields require extensive input of information. There is thus a need for a simple model that can predict runoff-related pesticide concentrations in many streams on a landscape level when only limited data are available. To validate such a model, the runoff-related pesticide load of 18 small lowland streams was predicted with an extended version of the model "simplified formula for indirect loadings caused by runoff" (available from the Organisation for Economic Cooperation and Development, OECD). The authors suggest that the model presented here is suitable for use in routine exposure assessment of pesticides on a landscape level, as all input data (soil, slope, precipitation, pesticide application) are readily available from public authorities or could be generated by simple regional flood hydrograph curves. The predicted concentrations were compared with measured concentrations obtained by runoff-triggered sampling. Fungicides, insecticides and herbicides were detected in 17 streams, with max. concentrations measuring up to 29.7 microg/l for the fungicide azoxystrobin and 0.3 microg/l for the insecticide parathion-ethyl. Herbicides were detected in 16 streams, with max. concentrations between 13.7 and 1.2 microg/l. The linear regression between the predicted and measured concentrations (log-values) shows significant correlations for the following pesticides: azoxystrobin: r2=0.43; p=0.03; epoxiconazole: r2=0.71; por=0.5 microg/l). PMID:15620762

The analytical capabilities of liquid chromatography with single-stage high-resolution mass spectrometry have been investigated with emphasis on qualitative aspects related to selective detection during screening and to identification. The study involved 21 different vegetable and fruit commodities, a screening database of 556 pesticides for evaluation of false positives, and a test set of 130 pesticides spiked to the commodities at 0.01, 0.05, and 0.20 mg/kg for evaluation of false negatives. The final method involved a QuEChERS-based sample preparation (without dSPE clean up) and full scan acquisition using alternating scan events without/with fragmentation, at a resolving power of 50,000. Analyte detection was based on extraction of the exact mass (±5 ppm) of the major adduct ion at the database retention time ±30 s and the presence of a second diagnostic ion. Various options for the additional ion were investigated and compared (other adduct ions, M + 1 or M + 2 isotopes, fragments). The two-ion approach for selective detection of the pesticides in the full scan data was compared with two alternative approaches based on response thresholds. Using the two-ion approach, the number of false positives out of 11,676 pesticide/commodity combinations targeted was 36 (0.3 %). The percentage of false negatives, assessed for 2,730 pesticide/commodity combinations, was 13 %, 3 %, and 1 % at the 0.01-, 0.05-, and 0.20-mg/kg level, respectively (slightly higher with fully automated detection). Following the SANCO/12495/2011 protocol for validation of screening methods, the screening detection limit was determined for 130 pesticides and found to be 0.01, 0.05, and ?0.20 mg/kg for 86, 30, and 14 pesticides, respectively. For the detected pesticides in the spiked samples, the ability for unambiguous identification according to EU criteria was evaluated. A proposal for adaption of the criteria was made. PMID:22664752

An analytical method employing gas chromatography (GC) with nitrogen-phosphorus detection has been developed for the simultaneous determination of eight insecticides (seven organophosphorus pesticides: ethoprophos, diazinon, chlorpyrifos-methyl, fenitrothion, malathion, chlorpyrifos and fenamiphos, and one thiadiazine: buprofezin) in banana leaves that are currently being used to feed cattle or hogs. The extraction and preconcentration of these pesticides were carried out using a modified QuEChERS procedure and the whole method was validated in terms of repeatability, linearity, precision and accuracy. Triphenylphosphate was used as internal standard. Matrix effect evaluation was also carried out using a matrix matched calibration. The developed procedure gave satisfactory recovery (89-104...

A multi-residue method was developed for the simultaneous determination of 85 current-use and legacy organochlorine pesticides in a single sediment sample. After microwave-assisted extraction, clean-up of samples was optimized using gel permeation chromatography and either stacked carbon and alumina solid-phase extraction cartridges or a deactivated Florisil column. Analytes were determined by gas chromatography with ion-trap mass spectrometry and electron capture detection. Method detection limits ranged from 0.6 to 8.9 ??g/kg dry weight. Bed and suspended sediments from a variety of locations were analyzed to validate the method and 29 pesticides, including at least 1 from every class, were detected.

Abstract in portuguese A exposição humana a substâncias tóxicas, incluindo agrotóxicos, pode levar a danos irreversíveis no organismo e até ao óbito, sendo considera um grave problema de saúde pública. Este é um estudo retrospectivo, que utilizou dados reportados ao Centro de Informação e Assistência Toxicológica do Distrito Federal, Brasil (Ciat-DF) referentes a intoxicações por agrotóxicos ocorridas no DF de 2004 a 2007. Nesse período, 709 intoxicações foram notificadas e (more) avaliadas neste estudo. A maioria dos indivíduos envolvidos nas intoxicações foi do sexo masculino (51,2%), intoxicados no domicílio (91%), em área urbana (86,3%) e por via oral (84%). Crianças de 1 a 4 anos e adultos de 20 a 39 anos estiveram envolvidos em 30 e 36% das intoxicações, respectivamente. As intoxicações acidentais corresponderam a 47,1% dos casos, seguidas pelas tentativas de suicídio (44,2%). O raticida ilegal chumbinho, conhecido por conter, principalmente, o inseticida carbamato aldicarbe, esteve envolvido em 35,1% dos casos, principalmente em tentativas de suicídio. Dezoito das intoxicações registradas evoluíram a óbito, 15 por suicídio e 3 por acidente individual. Quando comparado com outras fontes de dados, este estudo detectou uma alta taxa de subnotificação das intoxicações por agrotóxicos reportadas ao Ciat-DF no período do estudo. Abstract in english Exposure to toxic substances, including pesticides, can cause irreversible damage to humans, including death, and is therefore considered a serious public health problem worldwide. This is a retrospective study using data gathered by the Toxicological Information and Assistance Center of Brazil's Federal District (Ciat-DF) between 2004 and 2007. During this period, 709 intoxications with pesticide occurred in the DF and were analyzed in this study. Fifty-one percent of th (more) e intoxicated individuals were men; the events occurred mostly in the home (91%), in the urban area (86.3%) and by ingestion (84%). Children from 1 to 4 years of age and adults from 20 to 39 years were involved in 30% and 36% of the cases, respectively. Accidental intoxication corresponded to 47.1% of the cases, followed by attempted suicide (44.2%). The illegal rodenticide known as "chumbinho", the main ingredient of which is carbamate insecticide aldicarb, was involved in 35.1% of the cases, mostly in suicide attempts. In eighteen cases, the intoxicated individuals died after exposure to the pesticides, namely 15 suicides and 3 accidental poisonings. When compared with other data sources, this study identified a high level of underreporting to the Ciat-DF of intoxication by pesticide during the period under study.

Abstract in spanish Objetivo. Determinar la actividad de la acetilcolineterasa en trabajadores con riesgo de exposición a plaguicidas organofosforados y carbamatos y los plaguicidas más frecuentemente aplicados en los cultivos agrícolas en siete departamentos colombianos durante el período de 1998 a 2001. Material y métodos. De 1998 a 2001, participaron las entidades territoriales de salud de Boyacá, Caldas, Huila, Meta, Norte de Santander, Santander y Valle del Cauca, con 25.242 traba (more) jadores a quienes se les realizó la determinación de la actividad de la acetilcolinesterasa como biomarcador de exposición a estos plaguicidas mediante el método de Limperos y Ranta modificado por Edson. Resultados. Del total de trabajadores, el 78,9% eran hombres y 21,1% mujeres; el 38,8% se encontraba en un rango de edad de 26 a 40 años. El 66,1% reportó pertenecer a un régimen de seguridad social; los oficios con mayor número de trabajadores fueron: fumigador-aplicador con 39,1% y jornalero con 24,9%. Se realizaron 25.356 pruebas de acetilcolinesterasa, de las cuales, 7,6% mostraron resultados anormales. Conclusiones. Con relación a los plaguicidas de importancia en salud pública más usados, se encontraron los organofosforados con 42,4% seguido por carbamatos con 17,8%, insecticidas organoclorados con 8,4% y clorinados 6,6%, lo cual hace necesario ampliar el uso de biomarcadores para la vigilancia de trabajadores expuestos a plaguicidas no controlados por el programa. Abstract in english Objective. Acetylcholinesterase activity was measured in workers potentially exposed to pesticides that are frequently used in agriculture in 7 provinces in Colombia between 1998and 2001. Material and methods. During this period, local health centers in the Departments (provinces) of Boyacá, Caldas, Huila, Meta, Norte de Santander, Santander and Valle del Cauca monitored a total of 25,242 workers for acetylcholinesterase activity. The Limperos and Ranta method, modified (more) by Edson, was used to detect levels of pesticide exposure. Results. The worker sample consisted of 78.9% men and 21.1% women. Thirty-nine percent of the workers were between 26 and 40 years of age, and 66% had social security. The most common work activities were use of spray applicators (39.1%) and harvesters (24.9%). Of the 25,356 tests for acetylcholinesterase activity, 7.6% showed abnormal activity levels. Conclusion. In the zones investigated, organophosphosphates were the most commonly used pesticides (42.4%), followed by carbamates (17.8%), organochlorines (8.4%) and chlorinates (6.6%). The diversity of pesticides in use underlines the need to increase the variety of biomarkers for monitoring exposed workers.

Hydrogen cyanamide is a plant-growth regulator used on fruit crops, and has a high toxicity. In this study, a simple and sensitive method for detecting hydrogen cyanamide in fruit was developed. In the proposed method, cyanamide was extracted with water from homogenized fruit samples (grape, kiwi, and peach). The extract was purified through twice liquid?liquid extraction. Then, the purified extract was derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Finally, the cyanamide derivative was analyzed using HPLC with fluorescence detection. This method was validated at 2, 0.2, and 0.01?mg?kg?1 cyanamide. The recovery rates were between 87.1 and 96.6?%, and the intraday and interday reproducibilities were within 1.8 and 2.2?%, respectively. The limits of detection and quantific...

This study presents the potential of multiple headspace solid-phase microextraction (multiple HS-SPME) for the quantification of analytes in solid samples. Multiple HS-SPME shares the same advantages as SPME. It also enables a complete recovery of the target compound and therefore the matrix effect, which commonly appears in SPME-based analysis, is avoided. A method based on multiple HS-SPME for the determination of the toxic contaminant ethyl carbamate (EC) in bread samples has been developed and validated, using gas chromatography with flame ionization detector. A novel polyethylene glycol/hydroxy-terminated silicone oil fiber was prepared for the first time and subsequently used instead of commercial ones because of its high extraction ability and good operational stability. An importan...

Intensive use of pesticides, particularly dithiocarbamates, in agriculture often leads to contamination of freshwater ecosystems. To our knowledge, the mechanisms of toxicity to fish by the carbamate fungicide Tattoo that contains mancozeb [ethylenebis(dithiocarbamate)] have not been studied. The present study aimed to evaluate the effects of Tattoo on goldfish gills and blood, tissues that would have close early contact with the pollutant. Exposure of goldfish Carassius auratus to 3, 5 or 10mgL(-1) of Tattoo for 96h resulted in moderate lymphopenia (by 8 percent) with a concomitant increase in both stab (by 66-88 percent) and segmented (by 166 percent) neutrophils. An increase in the content of protein carbonyl groups in blood (by 137-184 percent) together with decreased levels of protein thiols (by 23 percent) and an enhancement of lipid peroxide concentrations (by 29 percent) in gills after exposure to 10mgL(-1) of Tattoo demonstrated the induction of mild oxidative stress in response to Tattoo exposure. At the same time, the activities of selected antioxidant enzymes were enhanced in gills: superoxide dismutase by 18-25 percent and catalase by 27 percent. A 34 percent increment in low molecular mass thiol concentrations (mainly represented by glutathione) also occurred in gills and could be related to increased activity (by 13-30 percent) of glucose-6-phosphate dehydrogenase. The results indicate that Tattoo exposure perturbs free radical processes, i.e. induces mild oxidative stress and enhances the activity of certain antioxidant and associated enzymes in goldfish gills. It is clear that goldfish respond to the presence of waterborne pesticide by adjusting antioxidant defenses through upregulation of activities of antioxidant and associated enzymes. PMID:22963715

A new analytical method for the determination of 14 pesticide residues in fresh peppermint was developed based on the QuEChERS sample preparation technique followed by gas chromatography coupled to electron capture and nitrogen phosphorus detectors (GC/ECD/NPD). The validation study clearly demonstrated suitability of the method for its intended application. The overall recoveries of the pesticides from peppermint, at the three spiking levels of 0.01, 0.1 and 1.0?mg?kg?1, were 100?%???10?% with relative standard deviations of 6?%???5?% on average. The limit of quantification was 0.01?mg?kg?1 for all the pesticides. The expanded uncertainties were in the range between 7?% and 30?% (14?% on average), which was distinctively less than a maximum default value of ?50?%. Compared with our previo...

In this work, the capability of gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF MS) for quantitative analysis of pesticide residues has been evaluated. A multiclass method for rapid screening of pesticides (insecticides, acaricides, herbicides and fungicides) in fruit and vegetable matrices has been developed and validated, including detection, identification and quantification of the analytes. To this aim, several food matrices were selected: high water content (apples, tomatoes and carrots), high acid content (oranges) and high oil content (olives) samples. The well known QuEChERS procedure was applied for extraction of pesticides, and matrix-matched calibration using relative responses versus internal standard was used for quantification. The sample extracts were ...

A new material based on poly(methyltetradecylsiloxane) (PMTDS) thermally immobilized onto a silica support has been tested as a sorbent for the solid-phase extraction (SPE) from water of several pesticides used in soybean cultivation. The SPE methodology was developed and validated for six of these pesticides (imazethapyr, imazaquin, metsulfuron-methyl, bentazone, chlorimuron-ethyl and tebuconazole) according to the International Conference on Harmonization directives and the results were compared with those obtained with a commercial C18 SPE cartridge. The PMTDS-based sorbent gives results similar to the commercial sorbent with recoveries and precisions in agreement with directives for residue analysis. The quantification limits, after concentration, of all the pesticides evaluated were 1.0 microg L(-1), below the levels imposed by the principal regulatory agencies. The PMTDS-based sorbent preparation is fast, easy and reproducible and the cartridges are less expensive than similar commercial SPE materials. PMID:17386471

Surface runoff is one of the most important pathways for pesticides to enter surface waters. Mathematical models are employed to characterize its spatio-temporal variability within landscapes, but they must be simple owing to the limited availability and low resolution of data at this scale. This study aimed to validate a simplified spatially-explicit model that is developed for the regional scale to calculate the runoff potential (RP). The RP is a generic indicator of the magnitude of pesticide inputs into streams via runoff. The underlying runoff model considers key environmental factors affecting runoff (precipitation, topography, land use, and soil characteristics), but predicts losses of a generic substance instead of any one pesticide. We predicted and evaluated RP for 20 small strea...

Dimethoate, diazinon, parathion methyl, pirimiphos methyl, malathion, fenthion, chlorpyriphos, methidathion and azinphos methyl were determined in 71 olive oil samples produced in Chile from different varieties of olives (arbequina, frantoio, picual, lechino and blend) at three different harvest periods (2007, 2008 and 2009). The target pesticides were determined using a validated analytical method based on microwave-assisted liquid-liquid and solid-phase extraction with subsequent GC-FPD detection and GC-MS/MS for confirmation purposes. In 79% of the samples, five of the nine pesticides tested were detected with a frequency of one pesticide per sample. The highest detection rates were observed for the residues of chlorpyriphos and diazinon. The average concentration of chlorpyriphos, diaz...

A modified version of the QuEChERS method has been developed for the determination of a group of ten organophosphorus pesticides (i.e. ethoprofos, dimethoate, diazinon, malaoxon, chlorpyrifos-methyl, fenitrothion, malathion, chlorpyrifos, fenamiphos and phosmet) and one thiadiazine pesticide (buprofezin) in three different types of soils (forestal, ornamental and agricultural). The method was validated through linearity, recovery, precision and accuracy studies, and also by carrying out a matrix-matched calibration for the three soils owing to the existence of a strong matrix effect. Acceptable recovery values were obtained (between 45 and 96%) for all the pesticides and soils, except for malathion and malaoxon in forestal and ornamental soils, from which they could not be quantitatively extracted. Limits of detection of the whole method ranged between 0.48 and 7.78 ng/g. The method was finally applied to the determination of chlorpyrifos concentration in a treated soil for cultivation of potatoes. PMID:20127321

PestLCI is a new, modular model for estimation of pesticide emissions from field application to the different environmental compartments. It calculates emission fractions to the air, water, soil and groundwater compartments of the environment based on generally available information about: Type and time of application, crop species and development stage, and properties of the pesticide active ingredients. The required physical-chemical information on the 69 organic pesticides approved for field-use in Denmark is included in the model as a data base. So is the relative leaf area for 28 common European crops on 2-5 development stages together with meteorological data for 12 stations in Denmark. The use and capability of the model is illustrated through Danish case studies but the modular structure of the model will allow its adaptation to conditions valid for other regions.

The stereoisomers of metolachlor and its two polar metabolites [ethane sulfonic acid (ESA) and oxanilic acid (OXA)] were separated using liquid chromatography-mass spectrometry (LC-MS) and capillary zone electrophoresis (CZE), respectively. The separation of metolachlor enantiomers was achieved using a LC-MS equipped with a chiral stationary phase based on cellulose tris(3,5-dimethylphenyl carbamate) and an atmospheric pressure chemical ionization source operated under positive ion mode. The enantiomers of ESA and OXA were separated using CZE with gamma-cyclodextrin (??-CD) as chiral selector. Various CZE conditions were investigated to achieve the best resolution of the ESA and OXA enantiomers. The optimum background CZE electrolyte was found to consist of borate buffer (pH = 9) containing 20% methanol (v/v) and 2.5% ??-CD (w/v). Maximum resolution of ESA and OXA enantiomers was achieved using a capillary temperature of 15??C and applied voltage of 30 kV. The applicability of the LC-MS and CZE methods was demonstrated successfully on the enantiomeric analysis of metolachlor and its metabolites in samples from a soil and water degradation study that was set up to probe the stereoselectivity of metolachlor biodegradation. These techniques allow the enantiomeric ratios of the target analytes to be followed over time during the degradation process and thus will prove useful in determining the role of chirality in pesticide degradation and metabolite formation. ?? 2005 Elsevier Ltd. All rights reserved.

Previous studies in euryhaline fish have shown that acclimation to hypersaline environments enhances the toxicity of thioether organophosphate and carbamate pesticides. To better understand the potential mechanism of enhanced toxicity, the effects of the organophosphate insecticide phorate were evaluated in coho salmon (Oncorhynchus kisutch) maintained in freshwater (<0.5 g/L salinity) and 32 g/L salinity. The observed 96-h LC50 in freshwater fish (67.34 ± 3.41 ?g/L) was significantly reduced to 2.07 ± 0.16 ?g/L in hypersaline-acclimated fish. Because organophosphates often require bioactivation to elicit toxicity through acetylcholinesterase (AChE) inhibition, the in vitro biotransformation of phorate was evaluated in coho salmon maintained in different salinities in liver, gills, and olfactory tissues. Phorate sulfoxide was the predominant metabolite in each tissue but rates of formation diminished in a salinity-dependent manner. In contrast, formation of phorate-oxon (gill; olfactory tissues), phorate sulfone (liver), and phorate-oxon sulfoxide (liver; olfactory tissues) was significantly enhanced in fish acclimated to higher salinities. From previous studies, it was expected that phorate and phorate sulfoxide would be less potent AChE inhibitors than phorate-oxon, with phorate-oxon sulfoxide being the most potent of the compounds tested. This trend was confirmed in this study. In summary, these results suggest that differential expression and/or catalytic activities of Phase I enzymes may be involved to enhance phorate oxidative metabolism and subsequent toxicity of phorate to coho salmon under hypersaline conditions. The outcome may be enhanced fish susceptibility to anticholineterase oxon sulfoxides. PMID:21488666

Abstract in english Six supercritical fluid extraction (SFE) methods were tested, by varying the following operational parameters: CO2 pressure, time and temperature of extraction, type and proportion of static modifier, and Hydromatrix®/sample rate into cell. Firstly, insecticide carbamates were extracted from spiked potatoes samples (fortification level of 0,5 mg.Kg-1) by using SPE procedures, and then final extracts were analyzed HPLC/fluorescence. Good performance was observed with SFE (more) methods that operated with values of temperature and CO2 pressure of 50 ºC and 350 bar, respectively. Best efficiency was obtained when it was used acetonitrile as a modifier (3% on the cell volume), and Hydromatrix®/sample rate of 2:1. Static time was of 1 min; total extraction time was of 35 min; dynamic extraction was performed with 15 mL of CO2, and it was used methanol (2 mL) for the dissolution of the final residue. In such conditions, pesticide recoveries varied from 72 to 94%, depending on the analyzed compound. In higher extraction temperatures, a rapid degradation was observed for some compounds, such as aldicarb and carbaryl; presence of their metabolites was further confirmed by HPLC-APCI/MS in positive mode. Detection limits for chromatographic analysis varied from 0,2 to 1,3 ng.

Cholinesterases form a family of serine esterases that arise in animals from at least two distinct genes. Multiple forms of these enzymes can be precisely localized and regulated by alternative mRNA splicing and by co- or posttranslational modifications. The high catalytic efficiency of the cholinesterases is quelled by certain very selective reversible and irreversible inhibitors. Owing largely to the important role of acetylcholine hydrolysis in neurotransmission, cholinesterase and its inhibitors have been studied extensively in vivo. In parallel, there has emerged an equally impressive enzyme chemistry literature. Cholinesterase inhibitors are used widely as pesticides; in this regard the compounds are beneficial with concomitant health risks. Poisoning by such compounds can result in an acute but usually manageable medical crisis and may damage the ONS and the PNS, as well as cardiac and skeletal muscle tissue. Some inhibitors have been useful for the treatment of glaucoma and myasthenia gravis, and others are in clinical trials as therapy for Alzheimer`s dementia. Concurrently, the most potent inhibitors have been developed as highly toxic chemical warfare agents. We review treatments and sequelae of exposure to selected anticholinesterases, especially organophosphorus compounds and carbamates, as they relate to recent progress in enzyme chemistry.

Over the past decade, molecular, biochemical and cellular markers have been extensively used in pollution monitoring of aquatic environments. Biochemical markers have been selected among early molecular events occurring in the toxicological mechanisms of main contaminants. This paper assesses the marine environment quality along the Tunisian coasts using a statistical approach. Clams (Ruditapes decussatus) were collected during the four seasons of 2003 on seven different sites from the Tunisian coasts. Oxidative stress was evaluated in gills using catalase activity (Cat), neutral lipids and malonedialdehyde accumulation. Glutathione S-transferase activity is related to the conjugation of organic compounds and was evaluated in both, gills and digestive glands. Acetylcholinesterase activity was evaluated as the biomarker of exposure to organophosphorous, carbamate pesticides and heavy metals. For each biomarker, a discriminatory factor was calculated and a response index allocated. For each site, a global response index was calculated as the sum of the response index of each biomarker. Discriminant analysis shows significant differences between sites and seasons compared with control sample. Faroua (site 1) and Menzel Jemile (site 2) seem to be the less polluted with respect to the other sites for all seasons. Gargour (site 6) shows the highest Multimarker Pollution Index during the four seasons, indicating higher contamination level. PMID:16076726

Reconnaissance-level sampling for selected nutrients, pesticides and surfactants in groundwater upgradient from the Idaho National Engineering Laboratory was conducted during June 1989. Water samples collected from eight irrigation wells, five domestic or livestock wells, and two irrigation canals were analyzed for nutrients, herbicides, insecticides and polychlorinated compounds, and surfactants. In addition to the above constituents, water samples from one irrigation well, one domestic well, and one irrigation canal were analyzed for arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. Concentrations of nitrite plus nitrate as nitrogen ranged from less than the reporting level to 6.10 mg/L and orthophosphate concentrations of 2,4-D in two water samples were 0.01 and 0.10 micrograms/L. Water samples analyzed from 15 other herbicides, 10 carbamate insecticides, 11 organophosphorus insecticides, and 15 organochlorine insecticides, gross polychlorinated biphenyls, and gross polychlorinated naphthalenes all had concentrations below their report levels. Concentrations of surfactant ranged from 0.02 to 0.35 mg/L. Arsenic, barium, chromium, selenium, and silver concentrations exceeded reporting levels in most of the samples.

Multiresidue methods (MRMs) for pesticides residues determination in fruit and vegetables, based on GC-MS, are mainly performed in electron impact ionization mode. However an important group of them provide much better response working in negative chemical ionization mode due to the elimination of a high percentage of background signal. Considering that a selective and sensitive method has been developed for the determination of multiclass pesticide residues in different commodities by GC-MS with a triple stage quadrupole analyzer (GC-TSQ-MS); the pesticide signal has been optimized in MS-MS whilst working in negative chemical ionization mode using methane as the reagent gas. The proposed method was fully validated for 53 compounds in tomato, apple and orange matrices. The obtained limits of determination were lower than 0.1?g/kg for more than 50% of the pesticides studied, and lower than 1?g/kg for all pesticides studied, except for cypermethrin, boscalid, bifenthrin and deltamethrin. Linearity was studied in the 0.5-50?g/kg range and a linear response was obtained for all pesticides in all matrices. Recoveries were evaluated at two different levels (1 and 50?g/kg) and recoveries were ranged between 70 and 120% in tomato, apple and orange, except in the cases of chlorfenapyr, ofurace, chlozolinate, chlorothalonil, tolylfluanid and dichlofluanid with recovery values close to 60% at 1?g/kg fortification levels. Repetitivity was evaluated and the relative standard deviation (RSD%) was lower than 10% in all cases. The developed method was employed in the analysis of real samples intended for baby food and the obtained results showed that 50% of the samples were positive for different pesticide residues. The concentration range detected was between 5 and 100?g/kg. The positive detection of OCs was particularly noticeable; these included chlorothalonil, fenhexamide, clorpyrifos and lambda cyhalothrin, which are very persistent and toxic with low acute reference dose. Endosulfan sulfate, which is not approved, was detected at a low concentration. PMID:23058941

The environmental risk assessment of pesticides in Europe is based on crop relevant exposure scenarios for the intended uses. A tiered FOCUSsw modelling approach (Step 1-4) is used to provide harmonised exposure data for the aquatic risk assessment. At FOCUSsw Step 3 exposure is modelled in different water bodies (pond, ditch and stream) in 10 scenarios representing geo-climate conditions across Europe. The model provides estimates of surface water concentration, based on the intended use, taking into account potential input routes (drift, drainage and run-off). Leaching and subsequent transport through the drainage system poses an important contamination pathway allowing rapid transport of pesticides to the surface water system. With FOCUSsw this input is modelled via the 1 dimensional root zone model MACRO allowing preferential transport to occur in the unsaturated zone. Although models (such as MACRO) are widely used within the registration process, their validation requires further work, not least becauseof the limited availability of field data. The Danish Pesticide Leaching Assessment Programme (PLAP), an intensive monitoring programme which is used to evaluate the risk of leaching of pesticides under field conditions, aims to analyse whether pesticides applied in accordance with granted uses enter the aquatic environment in unacceptable concentrations. Within this programme a high resolution data set comprising 10 years of various pesticide concentrations in drainage from 3 field sites (1.7 – 2.3 ha, sandy loam) are available for model validation. Moreover, a “site specific” setup of the MACRO model already calibrated and validated with respect to water and non reactive solute transport is available from these field sites. For a sub-set of pesticides representing a range of use patterns and inherent properties (e.g. sorption potential, persistency and toxicity) output from drain to surface water has been assessed from both measured and modelled data. The latter comprising output from the MACROmodel parameterised either via the FOCUSsw setup (relevant scenarios) or the “site specific setup” applied at the PLAP sites. Output from monitoring and the two modelling approached are compared and uncertainties of the different approached are discussed. It is considered how monitoring data from post registration systems can be “optimised” in order to improve their usability in risk assessment (e.g. validation of modelling, output format).

A series of carbamates of the phenolic compound 1 were prepared and evaluated in vivo as its prodrug. Each carbamate was orally administered to rats, and plasma concentrations of the parent compound 1 were measured with the passage of time. We judged which carbamate was suitable for the prodrug of 1 from both the AUC value of 1 and absence of the carbamate in plasma. The AUC value of 1 after oral administration of 2b was approximately 40-fold higher than that for an administration of 1, and the bioconversion from 2b to 1 was excellent. As a whole, di-substituted carbamates resulted in higher plasma concentrations of 1 than did mono-substituted ones. However di-substituted carbamates were almost always detected in plasma. As a result, we found that the ethycarbamoyl derivative 2b demonstrates the best prodrug property in this series.   

A within-laboratory validation procedure for a selective and sensitive method for the simultaneous determination of 98 pesticide residues in mango is presented. QuEChERS extraction was adapted to laboratory conditions. Mango samples (10 g) mixed with sodium sulfate (4 g) and sodium acetate (1 g) were extracted with acetonitrile/acetic acid (99/1 v/v), cleaned using dispersive solids, and subsequently identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Pesticides were separated on a reversed-phase column using a gradient elution in conjunction with positive-mode electrospray ionisation. The analytical performance of the method was demonstrated by analysis of spiked mango samples at three concentration levels (0.01, 0.05 and 0.1 mg kg(-1)) for 3 different days, and the analysis was performed by three analysts. Calibration curves were statistically acceptable by the ordinary last-square method (OLSM), with a regression coefficient above 0.98 for all analytes. The method accuracy (n = 18) was between 80% and 110%, and precisions were below 20% for 95% of the analytes. The method uncertainty at the LOQ was evaluated considering the uncertainty associated with the calibration curve and the uncertainty associated with the method precision. The validation data for all pesticides were in accordance with Brazilian and European guidelines for pesticide residue analysis. PMID:22014095

A multi-residue analytical method for 185 pesticides (including metabolites) in meat products was validated by the guideline of the Japanese Ministry of Health, Labour and Welfare. This method involved extraction with ethyl acetate–cyclohexane (1 : 1) and cleanup by gel permeation chromatography (GPC), and primary secondary amine (PSA) and silica-gel mini-column solid-phase extraction (SPE). The target compounds were determined by gas chromatography/mass spectrometry (GC-MS) and liquid chromatography/mass spectrometry (LC-MS). Validation tests were performed on beef, chicken and pork muscles fortified at 0.01 and 0.10 ?g/g. Among 185 pesticides tested, 175 in beef, 175 in chicken and 172 in pork were found to conform to the guideline when the solvent standard was used, and 181 in beef, 176 in chicken and 177 in pork when the matrix-matched standard was used. Although significant matrix effects were not observed for most pesticides, use of the matrix-matched standard was preferable for accurate quantitation to the solvent standard. Limits of quantitation (S/N ?10) were set at 0.01 ?g/g for all pesticides. The method was applied to the regulatory monitoring of meat products.   

Abstract in spanish Mediante un método sencillo y de bajo costo basado en la inhibición de la actividad de las colinesterasas sérica y eritrocítica, se detectó la presencia de plaguicidas organofosforados y/o carbamatos en lechuga (Lactuca sativa), culantro (Coriandum santivum) y apio (Apium graveolens) obtenidos de las Ferias del Agricultor del Valle Central de Costa Rica. El porcentaje de inhibición de las colinesterasas se relaciona con la cantidad de plaguicida presente en el veget (more) al. El 13% del total de muestras analizadas resultaron ser positivas por estos plaguicidas al utilizar colinesterasa sérica como indicador y el 33% al utilizar colinesterasa eritrocítica. El lavado y el cocinado de los vegetales para ambas colinesterasas no causan mayor efecto en la eliminación del plaguicida pero tiende a disminuir ligeramente la concentración del mismo. Se encontró evidencia estadística altamente significativa (p = 0,0001) indicando que la colinesterasa eritrocítica presenta mayor sensibilidad analítica con respecto a la sérica. Es de suma importancia determinar la presencia de plaguicidas en los productos agrícolas que consumimos, pues éstos están expuestos a contaminación por fumigación directa, contaminación de los suelos y aguas de riego, y por lo general son productos que se consumen sin un lavado adecuado y sin cocción. Abstract in english Pesticide detection in Costarican vegetables based on the inhibition of serum and erythrocytic human cholinesterases. A simple and low cost method able to detect the presence of pesticides, organophosphates and carbamates based on the inhibition of serum and erythrocytic cholinesterases, was used in lettuce (Lactuca sativa), cilantro (Coriandum santivum) and celery (Apium graveolens) obtained from the Ferias del Agricultor from Valle Central of Costa Rica. The percentage (more) inhibition of cholinesterases is related to the presence of plaguicide in the vegetable. Thirteen percent of the analyzed samples were positive for plaguicides using serum cholinesterase and 33% for erythrocytic cholinesterase. Washing and cooking the vegetables does not eliminate the presence of plaguicides but they lower slightly the concentration. Statistical evidence (p = 0,0001) indicates that erythrocytic cholinesterase has higher analytical sensitivity than serum cholinesterase. It is very important to establish the degree of contamination with pesticides in these agricultural products because they are exposed to direct contamination by fumigation, soil contamination and irrigation water, and are products that are often consumed without adequate cooking and washing.

Acetylcholinesterase (AChE) activity has traditionally been monitored as a biomarker of organophosphate (OP) and/or carbamate exposure. However, AChE activity may not be the most sensitive endpoint for these agrochemicals, because OPs can cause adverse physiological effects at concentrations that do not affect AChE activity. Carboxylesterases are a related family of enzymes that have higher affinity than AChE for some OPs and carbamates and may be more sensitive indicators of environmental exposure to these pesticides. In this study, carboxylesterase and AChE activity, cytochrome P4501A (CYP1A) protein levels, and mortality were measured in individual juvenile Chinook salmon (Oncorhynchus tshawytscha) following exposure to an OP (chlorpyrifos) and a pyrethroid (esfenvalerate). As expected, high doses of chlorpyrifos and esfenvalerate were acutely toxic, with nominal concentrations (100 and 1 ??g/l, respectively) causing 100% mortality within 96 h. Exposure to chlorpyrifos at a high dose (7.3 ??g/l), but not a low dose (1.2 ??g/l), significantly inhibited AChE activity in both brain and muscle tissue (85% and 92% inhibition, respectively), while esfenvalerate exposure had no effect. In contrast, liver carboxylesterase activity was significantly inhibited at both the low and high chlorpyrifos dose exposure (56% and 79% inhibition, respectively), while esfenvalerate exposure still had little effect. The inhibition of carboxylesterase activity at levels of chlorpyrifos that did not affect AChE activity suggests that some salmon carboxylesterase isozymes may be more sensitive than AChE to inhibition by OPs. CYP1A protein levels were ???30% suppressed by chlorpyrifos exposure at the high dose, but esfenvalerate had no effect. Three teleost species, Chinook salmon, medaka (Oryzias latipes) and Sacramento splittail (Pogonichthys macrolepidotus), were examined for their ability to hydrolyze a series of pyrethroid surrogate substrates and in all cases hydrolysis activity was undetectable. Together these data suggest that (1) carboxylesterase activity inhibition may be a more sensitive biomarker for OP exposure than AChE activity, (2) neither AChE nor carboxylesterase activity are biomarkers for pyrethroid exposure, (3) CYP1A protein is not a sensitive marker for these agrochemicals and (4) slow hydrolysis rates may be partly responsible for acute pyrethroid toxicity in fish. ?? 2005 Elsevier B.V. All rights reserved.

A study was conducted on raw cow?s milk to measure the residues of 15 organophosphorus pesticides used as dairy cattle ectoparasiticides or as insecticides in crops used for animal feed. For this purpose a previously devised method was improved and validated. The samples were collected directly from tank trucks during delivery of 3,974?tonnes of raw milk at nine Italian dairy plants. Approximately 4.4% of the 298 samples analyzed contained residues only in traces. The main pollutant was chlorpyriphos.

...Renovation, Repair and Painting Activities in Target...renovation, repair and painting program in accordance...and Pesticides Branch, Water, Wetlands, and Pesticides...and Pesticides Branch, Water, Wetlands, and Pesticides...renovation, repair and painting program in...

...Pesticide Petition Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petition Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petition Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...regulations in 40 CFR part 180 for residues of pesticide chemicals in or on...

...Several Pesticide Petitions for Residues of Pesticide Chemicals in or on Various...establishment of regulations for residues of pesticide chemicals in or on various...regulations in 40 CFR part 180 for residues of pesticide chemicals in or on...

...Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petition Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...regulations in 40 CFR part 180 for residues of pesticide chemicals in or on...

...Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petition Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

...Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...modification of regulations for residues of pesticide chemicals in or on various...CFR part 174 or part 180 for residues of pesticide chemicals in or on...

Epidemiologists frequently rely on self-reported information regarding a variety of exposures including smoking history, medication use, and occupational exposure because other sources of information are either unavailable or difficult to obtain. One way to evaluate the accuracy of self-reported information is through logic checks using other sources. To assess the quality of the self-reported pesticide product use history of 57,311 licensed pesticide applicators in the Agricultural Health Study (AHS), we compared the self-reported decade of first use and total years of use to the year the pesticide active ingredient was first registered for use. We obtained pesticide active ingredient registration information from the United States Environmental Protection Agency (USEPA) and other publicly available sources for the 52 pesticides on the AHS initial questionnaires administered from 1994 to 1997. Based on the registration year, we assessed 19 pesticides for potential inaccuracies regarding duration of use or decade of first use. When calculating potential total years of use, we did not consider the impact of chemicals being removed from the market, since the possibility for continued use existed. The majority of respondents provided plausible responses for both decade of first use and total duration of use. On average, 1% of the subjects overestimated total possible duration of use, ranging from less than 1% for carbofuran and chlorpyrifos to 5% for imazethapyr. Decade of first use was also reasonably reported, although more subjects did not report decade of first use than duration of use, with an average of 6% of subjects missing decade information for an individual chemical. For subjects who reported a decade of first use, 98% gave plausible responses on average, with overestimates highest for cyanazine, introduced in 1971 (6% reported earlier use), and chlorimuron ethyl, introduced in 1985 (7% reported earlier use). This analysis provided the opportunity to consider only one source of potential overreporting of exposure, and while underreporting may have also occurred, we cannot evaluate its role nor the balance between these potential inaccuracies. While we are unable to validate directly the accuracy of a respondent's use of pesticides, this analysis suggests that participants provide plausible information regarding their pesticide use. PMID:12198579

A laboratory-made sorbent for solid-phase extraction (SPE) was obtained by thermal immobilization of poly(methyloctylsiloxane) (PMOS) onto silica. Cartridges packed with the new sorbent were used for the simultaneous determination of imazethapyr, nicosulfuron, diuron, linuron and chlorimuron-ethyl in water. These pesticides were separated and quantified using high-performance liquid chromatography with diode array detection (HPLC-DAD). The recoveries achieved with the laboratory-made PMOS cartridges were compared with those of some commercially available silica-based and polymer-based cartridges having C18, C8 and NH(2) pendant groups. Method validation using the laboratory-made sorbent was performed for the five pesticides at three fortifications levels (1x, 2x and 10x the limit of quantification of each pesticide). The laboratory-made PMOS cartridge has low cost preparation and showed good recoveries (72-111%) for all pesticides. Repeatability and intermediate precision were lower than 15%. Its performance was similar or even better, in some cases, than those of the commercial cartridges. PMID:16600261

An HPLC-MS/MS method for the analysis of three pesticides in strawberries was developed and validated. Recoveries were measured at three spiking levels and ranged from 85 to 99% (mean recoveries). The effects of processing of strawberries ranging from rinsing to jam production were investigated for the three fungicides tolylfluanid, fenhexamid and pyrimethanil, which were applied under field conditions. Kresoxim-methyl was also applied in the field, but was not found in any of the samples investigated. The effect of parameters such as preharvest interval, dose, harvest time and observed pesticide concentration after harvest (initial concentration, mg kg(-1)), were examined with respect to possible reduction of the pesticides. The results from rinsing showed that all three pesticides were reduced on average by 37% for tolylfluanid, by 34% for fenhexamid and by 19% for pyrimethanil. For tolylfluanid and fenhexamid, the initial concentration significantly affected the reduction. For fenhexamid, dose could also have a minor influence on reduction. For pyrimethanil, none of the parameters significantly influenced the reduction. For jam production, cooking significantly reduced tolylfluanid by an average of 91%. For fenhexamid and pyrimethanil, a smaller reduction was seen, 25% and 33%, respectively. The reduction of tolylfluanid and pyrimethanil was affected by the preharvest interval, while fenhexamid was affected by the initial concentration. The unit-to-unit variability of fungicide contents was also investigated and the variability factors for the three fungicides were from 1.9 to 2.8. PMID:13129790

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2(C15H14NS2)Cl], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl atom and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate...

In the title compound, [Zn2(C22H36NS2)4], two bidentate dithio­carbamate groups chelate directly to the ZnII atoms, whereas the two remaining dithio­carbamate ligands bridge the Zn atoms via a crystallographic inversion centre. The Zn atoms show a strongly distorted tetra­hedral geometry. Adding the...

One of the major drawbacks of aqueous alkanolamine based CO(2) capture processes is the requirement of significantly higher energy of regeneration. This weakness can be overcome by separating the CO(2)-captured product to regenerate the corresponding amine, thus avoiding the consumption of redundant energy. Replacing aqueous phase with more stable and practically nonvolatile imidazolium based room-temperature ionic liquid (RTIL) provided a viable approach for carbamate to crystallize out as supernatant solid. In the present study, regeneration capabilities of solid carbamates have been investigated. Diethanolamine (DEA) carbamate as well as 2-amino-2-methyl-1-propanol (AMP) carbamate were obtained in crystalline form by bubbling CO(2) in alkanolamine-RTIL mixtures. Hydrophobic RTIL, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf(2)N]), was used as aqueous phase substituent. Thermal behavior of the carbamates was observed by differential scanning calorimetry and thermogravimetric analysis, while the possible regeneration mechanism has been proposed through (13)C NMR and FTIR analyses. The results showed that decomposition of DEA-carbamate commenced at lower temperature (?55 °C), compared to that of AMP-carbamate (?75 °C); thus promising easy regeneration. The separation of carbamate as solid phase can offer two-way advantage by letting less volume to regenerate as well as by narrowing the gap between CO(2) capture and amine regeneration temperatures. PMID:22963662

N-monoalkyl-O-succinimidyl carbamates reached with primary and secondary amines to produce ureas. However, N,N-dialkyl-O-succinimidyl-carbamates reacted with primary and secondary amines, via succinimide ring opening, to afford N-(O-carbamoyl)-succinmonoamide derivatives. This ring opening trend w...

New carbamates that are highly selective for inhibition of Anopheles gambiae acetylcholinesterase (AChE) over the human enzyme might be useful in continuing efforts to limit malaria transmission. In this report we assessed 34 synthesized and commercial carbamates for their selectivity to inhibit the AChEs found in carbamate-susceptible (G3) and carbamate-resistant (Akron) An. gambiae, relative to human AChE. Excellent correspondence is seen between inhibition potencies measured with carbamate-susceptible mosquito homogenate and purified recombinant wild-type (WT) An. gambiae AChE (AgAChE). Similarly, excellent correspondence is seen between inhibition potencies measured with carbamate-resistant mosquito homogenate and purified recombinant G119S AgAChE, consistent with our earlier finding that the Akron strain carries the G119S mutation. Although high (100- to 500-fold) WT An. gambiae vs human selectivity is observed for several compounds, none of the carbamates tested potently inhibits the G119S mutant enzyme. Finally, we describe a predictive model for WT An. gambiae tarsal contact toxicity of the carbamates that relies on inhibition potency, molecular volume, and polar surface area. PMID:22989775

The reaction of 3-chlorocarbonyl derivatives of bile acid esters with O,O-, N,N-, and S,S-dinucleophiles provides a general and efficient entry into steroid dimers with bis-carbamate, bis-carbonate, and bis-monothiocarbonate moieties in the linker fragment. The macrocyclization of the bis-carbamate 10 afforded the dimeric and tetrameric cholaphanes, 15 and 16, respectively.

The separation factor for carbon isotope exchange reaction between CO{sub 2} and amine in nonaqueous solvent was related to absorption reaction of CO{sub 2} in a solution. The test solutions were mixtures of primary amine (such as butylamine and tert-butylamine) or secondary amine (such as diethylamine, dipropylamine and dibutylamine) diluted with nonpolar solvent (octane or triethyalmine) or polar solvent (methanol), respectively. The isotope exchange reaction consists of three steps related to chemical reaction of CO{sub 2} in amine and nonaqueous solvent mixture, namely the reaction between CO{sub 2} and carbamic acid, that between CO{sub 2} and amine carbamate, and that between CO{sub 2} and carbamic ion. Above all, the isotope separation factor between CO{sub 2} and carbamic acid had the highest value. The overall separation factor can be higher in amine-nonaqueous solvent mixture where the concentration of carbamic acid becomes higher. (author).

Abstract in portuguese Agrotóxicos e raticidas são responsáveis por inúmeras intoxicações humanas e animais. Dados preliminares sugerem que o uso ilegal desses compostos com a finalidade de intoxicação fatal em pequenos animais é uma prática comum na região central do Estado do Rio Grande do Sul. O Laboratório de Toxicologia (LATOX) recebe amostras de casos em que a principal suspeita é a intoxicação por agrotóxicos ou raticidas (lícitos e ilícitos). O presente estudo teve com (more) o objetivo apresentar um levantamento das intoxicações de pequenos animais, analisadas pelo LATOX no período de 2004 a 2008, sendo identificados os xenobióticos por meio de métodos analíticos otimizados pelo laboratório, incluindo screening por cromatografia em camada delgada (CCD) e possível confirmação por cromatografia líquida de alta eficiência (CLAE-UV). No período, foram analisadas 68 amostras oriundas de intoxicações em cães e gatos. As amostras biológicas analisadas foram o estômago e o conteúdo estomacal, das quais a CCD permitiu a identificação de carbamatos, warfarina e estricnina. Esta mostrou ser uma técnica qualitativa eficiente e adequada para esse propósito, além de ser relativamente rápida, de baixo custo e de sofrer pouca interferência de componentes da matriz. Também foi realizado um screening toxicológico por CLAE-UV para os carbamatos n-metilados: aldicarb, carbaril, carbofuran e propoxur. O resultado das análises indicou que o principal agente tóxico encontrado foi o aldicarb (chumbinho), responsável por 39,7% das intoxicações (27 casos), seguido por estricnina (seis casos), warfarina (três casos) e monofluoracetato de sódio (um caso). Sendo assim, o "chumbinho" foi o principal agente envolvido em intoxicações de cães e gatos na região central do Estado no período avaliado, e os métodos analíticos CCD e CLAE-UV podem ser utilizados de forma eficiente na rotina laboratorial para identificação e confirmação dos xenobióticos mais envolvidos nessas intoxicações. Abstract in english The pesticides and rodenticides are responsible for several human and animal intoxications. Preliminary data suggest that the illegal use of these compounds to poison small animals is a common practice in the central region of the Rio Grande do Sul state. The Laboratory of Toxicology received samples, of cases in which the main suspected cause of death is poisoning by pesticides or exogenous rodenticides (licit and illicit). The aim of this study was show the survey of sm (more) all animals poisoned and analyzed by LATOX during the period of 2004 to 2008 identifying the xenobiotics by optimized analytical methods, including screening by thin-layer chromatography (TLC) and a possible confirmation by high performance liquid chromatography - ultraviolet detection (HPLC-UV). In this period 68 samples were analyzed from small poisoned animals. The biological samples analyzed were stomach and stomach content and the TLC permitted carbamates, warfarin and stricnine identification. This proved to be an efficient and adequate technique for this purpose, relatively fast, inexpensive and with low matrix interference. The screening by HPLC for N-methyl carbamates was also realized: aldicarb, carbaryl, carbofuran and propoxur. The analysis showed that the main toxic agent found was aldicarb (chumbinho), responsible for 39.7% of poisoning (27 cases), followed by stricnine (6 cases), warfarin (3 cases) and sodium monofluoracetate (1 case). Thus, the 'chumbinho' was the main agent involved in dogs and cats poisoning in the central region of the state, during the analyzed period. The analytical methods TLC and HPLC can be used efficiently in laboratorial routine for identification and confirmation of xenobiotics involved in these poisonings.

Acetylcholinesterase (AChE) is a proven target for control of the malaria mosquito (Anopheles gambiae). Unfortunately, a single amino acid mutation (G119S) in An. gambiae AChE-1 (AgAChE) confers resistance to the AChE inhibitors currently approved by the World Health Organization for indoor residual spraying. In this report, we describe several carbamate inhibitors that potently inhibit G119S AgAChE and that are contact-toxic to carbamate-resistant An. gambiae. PCR-RFLP analysis was used to confirm that carbamate-susceptible G3 and carbamate-resistant Akron strains of An. gambiae carry wild-type (WT) and G119S AChE, respectively. G119S AgAChE was expressed and purified for the first time, and was shown to have only 3% of the turnover number (k(cat)) of the WT enzyme. Twelve carbamates were then assayed for inhibition of these enzymes. High resistance ratios (>2,500-fold) were observed for carbamates bearing a benzene ring core, consistent with the carbamate-resistant phenotype of the G119S enzyme. Interestingly, resistance ratios for two oxime methylcarbamates, and for five pyrazol-4-yl methylcarbamates were found to be much lower (4- to 65-fold). The toxicities of these carbamates to live G3 and Akron strain An. gambiae were determined. As expected from the enzyme resistance ratios, carbamates bearing a benzene ring core showed low toxicity to Akron strain An. gambiae (LC(50)>5,000 ?g/mL). However, one oxime methylcarbamate (aldicarb) and five pyrazol-4-yl methylcarbamates (4a-e) showed good to excellent toxicity to the Akron strain (LC(50)?=?32-650 ?g/mL). These results suggest that appropriately functionalized "small-core" carbamates could function as a resistance-breaking anticholinesterase insecticides against the malaria mosquito. PMID:23049714

A series of compounds representing four major pesticide groups were tested for toxicity to beneficial insects representing four different insect orders: Coleoptera (Coccinellidae), Hemiptera (Anthocoridae), Hymenoptera (Aphelinidae), and Neuroptera (Chrysopidae). These materials included organophosphates (methidathion, esfenvalerate and phosmet), carbamates (carbofuran, methomyl and carbaryl), pyrethroids (bifenthrin, fenpropathrin, zeta-cypermethrin, cyfluthrin and permethrin) and the oxadiazine indoxacarb. Toxicity to coccinellid and lacewing species was assessed by treating 1st instar larvae with the recommended field rate of commercial products, and two 10 fold dilutions of these materials, in topical spray applications. Adult Aphytis melinus Debach and 2nd instar Orius insidiosus (Say) were exposed to leaf residues of the same concentrations for 24 h. ANOVA performed on composite survival indices derived from these data resolved significant differences among materials with respect to their overall toxicity to beneficial insects. Cyfluthrin, fenpropathrin and zeta-cypermethrin all increased the developmental time of the lacewing and one or more coccinellid species for larvae that survived topical applications. Bifenthrin increased developmental time for two coccinellid species and decreased it in a third. Indoxacarb (Avaunt® WG, DuPont Corp.) ranked highest overall for safety to beneficial insects, largely because of its low dermal toxicity to all species tested. Zeta-cypermethrin (Super Fury®, FMC Corporation) received the second best safety rating, largely because of its low toxicity as a leaf residue to A. melinus and O. insidiosus. Phosmet (Imidan® 70W, Gowan Co.) and methidathion (Supracide® 25W, Gowan Co.) ranked high for safety to coccinellid species, but compounds currently recommended for use in citrus such as fenpropathrin (Danitol® 2.4EC, Sumimoto Chem. Co.) and carbaryl (Sevin® XLR EC, Rhone Poulenc Ag. Co.) ranked very low for IPM-compatibility based on their relatively high toxicity to all species tested. Abbreviation: FR field rate

Tibial dyschondroplasia (TD) is characterized by expansion of the proximal growth plates of the tibiotarsus that fail to form bone, lack blood vessels, and contain non-viable cells. Thiram (a carbamate pesticide), when fed to young broiler chicks, induces TD with high regularity and precision. We used this experimental model to understand the cause of the defects associated with TD by selecting and identifying the genes differentially expressed in the TD growth plate of broiler chickens. Broiler chicks at 7 days of age were randomly divided into two groups. After fasting overnight, they were fed with regular diet (control) or the same diet containing 100 mg/kg thiram for 96 h to induce TD (thiram-fed). mRNA was purified from the growth plates of control and thiram-fed broilers. Forward and reverse-subtracted cDNA libraries were generated by suppression subtractive hybridization technology. Ten selected genes from cDNA libraries were identified by real-time quantitative polymerase chain reaction. All were differentially expressed in TD growth plates (P<0.05 or P<0.01). The levels of collagen type X (Col X), pro-alpha-1 collagen type I (Col I alpha1), collagen type IX (Col IX), NADH dehydrogenase (NADH DH), cytochrome C oxidase subunit III (COX III), enolase 1, alpha (ENO1), carbonic anhydrase II (CA2) and heat shock protein 90 (Hsp90) mRNA transcripts were up-regulated, while the expression levels of Matrilin 3 (MATN3) and chondromodulin-I (ChM-I) were down-regulated. Col I and Hsp90 were detected by immunohistochemistry at different stages. Given that these genes are involved in matrix formation, endochondral ossification, developmental regulation, electron transport in the mitochondrial respiratory chain and vascularization, our findings may provide new insights into understanding the pathogenesis of TD. PMID:19322716

Thyroid disease is common, and evidence of an association between organochlorine exposure and thyroid disease is increasing. The authors examined the cross-sectional association between ever use of organochlorines and risk of hypothyroidism and hyperthyroidism among female spouses (n = 16,529) in Iowa and North Carolina enrolled in the Agricultural Health Study in 1993-1997. They also assessed risk of thyroid disease in relation to ever use of herbicides, insecticides, fungicides, and fumigants. Prevalence of self-reported clinically diagnosed thyroid disease was 12.5%, and prevalence of hypothyroidism and hyperthyroidism was 6.9% and 2.1%, respectively. There was an increased odds of hypothyroidism with ever use of organochlorine insecticides (adjusted odds ratio (OR(adj)) = 1.2 (95% confidence interval (CI): 1.0, 1.6) and fungicides (OR(adj) = 1.4 (95% CI: 1.1, 1.8) but no association with ever use of herbicides, fumigants, organophosphates, pyrethroids, or carbamates. Specifically, ever use of the organochlorine chlordane (OR(adj) = 1.3 (95% CI: 0.99, 1.7), the fungicides benomyl (OR(adj) = 3.1 (95% CI: 1.9, 5.1) and maneb/mancozeb (OR(adj) = 2.2 (95% CI: 1.5, 3.3), and the herbicide paraquat (OR(adj) = 1.8 (95% CI: 1.1, 2.8) was significantly associated with hypothyroidism. Maneb/mancozeb was the only pesticide associated with both hyperthyroidism (OR(adj) = 2.3 (95% CI: 1.2, 4.4) and hypothyroidism. These data support a role of organochlorines, in addition to fungicides, in the etiology of thyroid disease among female spouses enrolled in the Agricultural Health Study. PMID:20061368

A series of compounds representing four major pesticide groups were tested for toxicity to beneficial insects representing four different insect orders: Coleoptera (Coccinellidae), Hemiptera (Anthocoridae), Hymenoptera (Aphelinidae), and Neuroptera (Chrysopidae). These materials included organophosphates (methidathion, esfenvalerate and phosmet), carbamates (carbofuran, methomyl and carbaryl), pyrethroids (bifenthrin, fenpropathrin, zeta-cypermethrin, cyfluthrin and permethrin) and the oxadiazine indoxacarb. Toxicity to coccinellid and lacewing species was assessed by treating 1st instar larvae with the recommended field rate of commercial products, and two 10 fold dilutions of these materials, in topical spray applications. Adult Aphytis melinus Debach and 2nd instar Orius insidiosus (Say) were exposed to leaf residues of the same concentrations for 24 h. ANOVA performed on composite survival indices derived from these data resolved significant differences among materials with respect to their overall toxicity to beneficial insects. Cyfluthrin, fenpropathrin and zeta-cypermethrin all increased the developmental time of the lacewing and one or more coccinellid species for larvae that survived topical applications. Bifenthrin increased developmental time for two coccinellid species and decreased it in a third. Indoxacarb (Avaunt WG, DuPont Corp.) ranked highest overall for safety to beneficial insects, largely because of its low dermal toxicity to all species tested. Zeta-cypermethrin (Super Fury), FMC Corporation) received the second best safety rating, largely because of its low toxicity as a leaf residue to A. melinus and O. insidiosus. Phosmet (Imidan 70W, Gowan Co.) and methidathion (Supracide 25W, Gowan Co.) ranked high for safety to coccinellid species, but compounds currently recommended for use in citrus such as fenpropathrin (Danitol 2.4EC, Sumimoto Chem. Co.) and carbaryl (Sevin XLR EC, Rhone Poulenc Ag. Co.) ranked very low for IPM-compatibility based on their relatively high toxicity to all species tested. PMID:15841234

An ultra-high-performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous quantification and identification of 116 pesticide residues which were most widely used in plants used in Traditional Chinese Medicine (TCM) in 15 min has been developed and validated. Samples were extracted and cleaned up with modified QuEChERS method and detected by UHPLC-MS/MS under multiple reactions monitoring mode, and quantified by matrix-match calibration. The validation study was carried out on five different matrixes following DG SANCO/2007/3131 of the European Quality Control Guidelines. The linearity of the calibration was good between 5 and 100 ng ml?¹ concentration ranges, and the limits of quantification (LOQs) less than 0.01 mg/kg for most pesticides. The mean recoveries of almost all pesticides were in the range from 70% to 120% at three concentration levels ranging from 0.01 mg/kg to 0.1mg/kg with relative standard deviations (RSD) better than 15%. The method was applied on 138 real samples from 102 different kinds of Chinese herbal medicine. 95 positive samples were detected. This method is fast, robust, accurate, selective, sensitive and easy to operate. PMID:22257925

This paper reports the development of a method to control the flow rate of fluids within paper-based microfluidic analytical devices. We demonstrate that by simply sandwiching paper channels between two flexible films, it is possible to accelerate the flow of water through paper by over 10-fold. The dynamics of this process are such that the height of the liquid is dependent on time to the power of 1/3. This dependence was validated using three different flexible films (with markedly different contact angles) and three different fluids (water and two silicon oils with different viscosities). These covered channels provide a low-cost method for controlling the flow rate of fluid in paper channels, and can be added following printing of reagents to control fluid flow in selected fluidic channels. Using this method, we redesigned a previously published bidirectional lateral flow pesticide sensor to allow more rapid detection of pesticides while eliminating the need to run the assay in two stages. The sensor is fabricated with sol-gel entrapped reagents (indoxyl acetate in a substrate zone and acetylcholinesterase, AChE, in a sensing zone) present in an uncovered "slow" flow channel, with a second, covered "fast" channel used to transport pesticide samples to the sensing region through a simple paper-flap valve. In this manner, pesticides reach the sensing region first to allow preincubation, followed by delivery of the substrate to generate a colorimetric signal. This format results in a uni-directional device that detects the presence of pesticides two times faster than the original bidirectional sensors. PMID:23079674

Abstract in portuguese O presente trabalho tem como objetivo aplicar uma metodologia multiresíduo visando a determinação de pesticidas em frutas e vegetais, utilizando extração com fluido supercrítico e análise por cromatografia gasosa e detector por captura de elétrons e espectrometria de massas. Um método convencional por extração sólido-líquido baseado na literatura e um método com fluido supercrítico desenvolvido, foram aplicados na determinação simultânea de 32 pesticidas (more) de 4 classes diferentes (organoclorados, organonitrogenados, organofosforados e piretróides) em amostras de alface, batata, maçã e tomate. As recuperações obtidas para a maioria dos pesticidas foram de 74% a 96% para ambos os métodos em níveis entre 0,04 - 0,10 mg kg-1, os limites de quantificação (dependendo da matriz e do pesticida) foram menores que 0,01 mg kg-1. SFE mostrou-se vantajosa quando comparada à extração sólido-líquido como economia de solventes, tempo e custos, podendo ser aplicada no monitoramento de pesticidas em alimentos. Abstract in english The aim of this paper was to apply a multiresidue method using Supercritical Fluid Extraction (SFE) and capillary gas chromatography with electron capture and mass spectrometry detections in the analysis of the levels of pesticide residues in fruits and vegetables. Single laboratory validation of both solid-liquid and supercritical fluid extraction methods was carried out for 32 compounds selected from four pesticide classes (organochlorine, organonitrogen, organophosphor (more) us and pyretroid) in blank and fortified samples of fresh lettuce, potato, apple and tomato. Recoveries for the majority of pesticides from fortified samples at fortification level of 0.04-0.10 mg kg-1 ranged 74-96% for both methods and confirmation of pesticide identity was performed by gas-chromatography-mass spectrometry in a selected-ion monitoring mode. Both methods showed good limits of detection (less 0.01 mg kg-1, depending on the pesticide and matrix) and the SFE method minimized environmental concerns, time, and laboratory work.

The analysis of a wide range of pesticides in wastewaters (WWs) undergoing different treatments (both modern and conventional) has been studied. The need for optimizing specific extraction methods for each WW effluent based on their physico-chemical characteristics has been considered. A distribution study was performed to establish if the filtration step before extraction is a correct procedure since pesticides can be more prone to be in the aqueous or the solid phase, depending on their hydrophobicity. This evaluation demonstrated that pesticides are distributed between the aqueous phase and the suspended particulate matter (SPM; e.g. pyrethroids are only found in the SPM). The proposed methodologies involved the determination of 39 polar and 139 non-polar pesticides using solid-phase extraction (SPE) and pressurized-liquid extraction (PLE) for the extraction of the aqueous phase and the SPM, respectively. Ultra high pressure liquid chromatography and gas chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS, GC-MS/MS) were used in the determination stage. WW samples from four different technologies were evaluated: membrane bioreactor, extended aeration, maturation pond and anaerobic pond. Validation data for the four effluents studied were generated, obtaining adequate precision values (estimated as % relative standard deviation, RSD) in almost all cases (<25%). The methods showed limits of detection at 0.01-0.20?gL(-1) and limits of quantification from 0.02 to 0.50?gL(-1). The proposed methods were applied to the analysis of real samples collected from an experimental WW treatment plant, detecting non-polar and polar pesticides at concentrations in the range 0.02-1.94?gL(-1) and 0.02-0.33?gL(-1), respectively. PMID:21035807

The validation of a multi-residue method for the determination of five neonicotinoid insecticides (imidacloprid, clothianidin, acetamiprid, thiacloprid and thiamethoxam) in honeybees is described. The method involves the extraction of pesticides using acetonitrile and liquid partitioning with n-hexane. One clean-up is then performed on a florisil cartridge (1 g, 6 mL) and the extract is analysed by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS). The recovery data were obtained by spiking honeybees samples free of pesticides at two concentration levels of the various neonicotinoids. The recoveries were in the range between 93.3 and 104.0% with relative standard deviation (RSD) less than 20%. The limit of quantification (LOQ) was 0.5 ng g-1 (correspondi...

A risk assessment tool for contaminated sites in low-permeability fractured media is developed, based on simple transient and steady-state analytical solutions. The tool, which explicitly takes into account the transport along fractures, covers different source geometries and can be applied to a wide range of compounds (conservative, sorbing, degradable). The superiority of this risk assessment tool compared to an Equivalent Porous Media (EPM) model is clearly demonstrated on experimental data. The use of the model for risk assessment is illustrated for diffuse pesticide sources in a Danish catchment. The model simulates well the presence of pesticides in drinking water wells and predicts the contamination duration, however, the early breakthrough and long term tailing cannot be validated due to lack of long term monitoring data.

Independent methods for determination of organic contaminants such as pharmaceuticals and pesticides in drinking water samples, using SPE as the extraction technique and LC-MS/MS in the MRM mode with electrospray ionization, were developed and validated. Different SPE sorbents were evaluated, including lab-made fluorinated and phenyl and commercial Oasis HLB and C18, with the commercial phases being more suitable for the target compounds. Recoveries in the range of 70-120% were obtained for all target compounds, with the exception for paracetamol (acetaminophen), and precision values (inter-day and intra-day), expressed in terms of relative standard deviations (RSD), lower than 20% were obtained for all target compounds. Quantification limits were in the range of 0.006-0.208?gL(-1) and the methods developed were successfully applied for the analysis of drinking water samples, detecting some pharmaceuticals and pesticides, but at concentration levels lower than the MRL. PMID:23141309

An alternative method has been developed to determine more than 50 pesticides in alcoholic beverages using hollow fibre liquid phase microextraction (HF-LPME) followed by ultra-high pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), without any further clean-up step. Pesticides were extracted from the sample to the organic solvent immobilized in the fibre and they were desorbed in methanol prior to chromatographic analysis. Experimental parameters related to microextraction such as type of organic solvent, extraction time and agitation rate have been optimized. The extraction method has been validated for several types of alcoholic beverages such as wine and beer, and no matrix effect was observed. The technique requires minimal sample handling and solvent co...

A rapid and simultaneous method for identification and quantification of pesticides residues in water samples have been developed and applied to the analysis of real samples. Tap and San Francisco River water samples were collected from Propria town and Aracaju city in the state of Sergipe, Brazil. A new single-drop microextraction (SDME) followed by gas chromatography-mass spectrometry techniques were used to determine the dimethoate, methyl parathion, ethion (organophosphates) and permethrin (pyrethroid) pesticides in water samples. The parameters linearity, linear range, precision, accuracy, sensitivity and robustness were studied for validation of the SDME/GC-MS method. An important point to this study is that plots of relative response and logarithmic concentrations were used to verif...

The ocelot (Felis pardalis) is an endangered neotropical cat distributed within a small range in the Lower Rio Grande Valley (LRGV), in Texas, U.S.A. Studies of the impacts of environmental contaminants in wild cats are few. Approximately one fourth of the estimated population (about 100) of ocelots in the LRGV was sampled to evaluate the impacts of chlorinated pesticides, polychlorinated biphenyls, and trace elements on the population. Hair was collected from 32 ocelots trapped between 1986-1992, and blood was collected from 20 ocelots trapped between 1993-1997. A few blood samples were obtained from individuals recaptured two or three times. Tissue samples from 4 road-killed ocelots were also analyzed. DDE, PCBs, and Hg were some of the most common contaminants detected in hair and blood. Mean Hg levels in hair ranged from 0.5 to 1.25 ??g g-1 dw, Se from 1.5 to 3.48 ??g g-1 dw, and Pb from 0.56 to 26.8 ??g g-1 dw. Mean DDE concentrations in plasma ranged from 0.005 ??g g-1 ww to 0.153 ??g g-1 ww, and PCBs ranged from 0.006 ??g g-1 ww to 0.092 ??g g-1 ww. Mean Hg levels in red blood cells ranged from 0.056 ??g g-1 dw to 0.25 ??g g-1 dw. Concentrations of DDE, PCBs, or Hg, did not increase significantly with age, although the highest concentrations of DDE and Hg were found in older animals. Overall, concentrations of DDE, PCBs, and Hg were low and at levels that currently do not pose any threat to health or survival of the ocelot. This is further supported by good reproduction of the ocelot in the LRGV, where adult females averaged about 1.5 kittens/litter. Thus, it seems that the current major threat to recovery of the ocelot in the LRGV may be habitat loss, although potential impacts of new generation pesticides, such as organophosphorus and carbamate insecticides need further study.The ocelot (Felis pardalis) is an endangered neotropical cat distributed within a small range in the Lower Rio Grande Valley (LRGV), in Texas, U.S.A. Studies of the impacts of environmental contaminants in wild cats are few. Approximately one fourth of the estimated population (about 100) of ocelots in the LRGV was sampled to evaluate the impacts of chlorinated pesticides, polychlorinated biphenyls, and trace elements on the population. Hair was collected from 32 ocelots trapped between 1986-1992, and blood was collected from 20 ocelots trapped between 1993-1997. A few blood samples were obtained from individuals recaptured two or three times. Tissue samples from 4 road-killed ocelots were also analyzed. DDE, PCBs, and Hg were some of the most common contaminants detected in hair and blood. Mean Hg levels in hair ranged from 0.5 to 1.25 ??g g-1 dw, Se from 1.5 to 3.48 ??g g-1 dw, and Pb from 0.56 to 26.8 ??g g-1 dw. Mean DDE concentrations in plasma ranged from 0.005 ??g g-1 ww to 0.153 ??g g-1 ww, and PCBs ranged from 0.006 ??g g-1 ww to 0.092 ??g g-1 ww. Mean Hg levels in red blood cells ranged from 0.056 ??g g-1 dw to 0.25 ??g g-1 dw. Concentrations of DDE, PCBs, or Hg, did not increase significantly with age, although the highest concentrations of DDE and Hg were found in older animals. Overall, concentrations of DDE, PCBs, and Hg were low and at levels that currently do not pose any threat to health or survival of the ocelot. This is further supported by good reproduction of the ocelot in the LRGV, where adult females averaged about 1.5 kittens/litter. Thus, it seems that the current major threat to recovery of the ocelot in the LRGV may be habitat loss, although potential impacts of new generation pesticides, such as organophosphorus and carbamate insecticides need further study.The impacts of PCBs, trace elements, and chlorinated pesticides on the endangered ocelot population in the Lower Rio Grande Valley, TX, was studied. Hair was sampled from 32 animals trapped during 1986-92 and blood was collected from 20 ocelots trapped during 1993-97. Mean mercury, selenium, and lead levels in hair were in the 0.5-1.25, 1.5-3.48, and 0.56-26.8 ??g/g

In this study, a new gas chromatography-mass spectrometry (GC-MS) method, using the very selective negative chemical ionization (NCI) mode, was developed and applied in combination with a modified acetonitrile-based extraction method (QuEChERS) for the analysis of a large number of pesticide residues (51 pesticides, including isomers and degradation products) in green coffee beans. A previously developed integrated sample homogenization and extraction method for both pesticides and mycotoxins analysis was used. An homogeneous slurry of green milled coffee beans and water (ratio 1:4, w/w) was prepared and extracted with acetonitrile/acetic acid (1%), followed by magnesium sulfate addition for phase separation. Aliquots from this extract could be used directly for LC-MS/MS analysis of mycotoxins and LC-amenable pesticides. For GC-MS analysis, a further clean-up was necessary. C18- and PSA-bonded silica were tested as dispersive solid-phase extraction (d-SPE) sorbents, separate and as a mixture, and the best results were obtained using C18-bonded silica. For the optimal sensitivity and selectivity, GC-MS detection in the NCI-selected ion monitoring (SIM) mode had to be used to allow the fast analysis of the difficult coffee bean matrix. The validation was performed by analyzing recovery samples at three different spike concentrations, 10, 20 and 50 ?g kg(-1), with 6 replicates (n=6) at each concentration. Linearity (r(2)) of calibration curves, estimated instrument and method limits of detection and limits of quantification (LOD(i), LOD(m), LOQ(i) and LOQ(m), respectively), accuracy (as recovery %), precision (as RSD%) and matrix effects (%) were determined for each individual pesticide. From the 51 analytes (42 parent pesticides, 4 isomers and 5 degradation products) determined by GC-MS (NCI-SIM), approximately 76% showed average recoveries between 70-120% and 75% and RSD ? 20% at the lowest spike concentration of 10 ?g kg(-1), the target method LOQ. For the spike concentrations of 20 and 50 ?g kg(-1), the recoveries and RSDs were even better. The validated LOQ(m) was 10, 20 and 50 ?g kg(-1) for respectively 33, 3 and 6 of the analytes studied. For five compounds, the European Union method performance requirements for the validation of a quantitative method (average recoveries between 70-120% and repeatability RSD ? 20%) were not achieved and 4 problematic pesticides (captan, captafol, folpet and dicofol) could not be detected as their parent compound, but only via their degradation products. Although the matrix effect (matrix-enhanced detector response) was high for all pesticides studied, the matrix interference was minimal, due to the high selectivity obtained with the GC-NCI-MS detection. Matrix-matched calibration for applying the method in routine analysis is recommended for reliable quantitative results. PMID:22771261

Brassinin hydrolase (BHAb), an inducible enzyme produced by the plant pathogen Alternaria brassicicola under stress conditions, catalyzes the hydrolysis of the methyl dithiocarbamate group of the phytoalexin brassinin, to indolyl-3-methanamine, methane thiol and carbonyl sulfide. Thirty four substrate inspired compounds, bioisosteres of brassinin and a range of related compounds, were evaluated as potential substrates and inhibitors of BHAb for the first time. While six compounds containing thiocarbamate, carbamate and carbonate groups displayed inhibitory activity against BHAb, only two were found to be substrates (thionecarbamate and dithiocarbamate). Methyl naphthalen-1-yl-methyl carbamate, the most potent inhibitor of the six, and methyl Nprime-(1-methyl-3-indolylmethyl)carbamate inhib...

The blue emission of a carbamic acid oligo(2-methyl-2-oxazoline) synthesized by a cationic ring-opening polymerization in supercritical carbon dioxide under controlled conditions is reported. The increase of the light-emission intensity of oligo(2-oxazoline)s was achieved by carbamic acid insertion at the oligomer starting end during the polymerization. Successful labeling of gram-positive S. aureus bacterial cells with carbamic acid ammonium-quaternized oligo(2-oxazoline)s turn these materials into promising blue fluorescent markers for imaging and bioanalytical assays.

One of the major factors contributing to surface water contamination in agricultural areas is the use of pesticides. The Soil and Water Assessment Tool (SWAT) is a hydrologic model capable of simulating the fate and transport of pesticides in an agricultural watershed. The SWAT model was used in this study to estimate stream flow and atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) losses to surface water in the Cedar Creek Watershed (CCW) within the St. Joseph River Basin in northeastern Indiana. Model calibration and validation periods consisted of five and two year periods, respectively. The National Agricultural Statistics Survey (NASS) 2001 land cover classification and the Soil Survey Geographic (SSURGO) database were used as model input data layers. Data from the St. Joseph River Watershed Initiative and the Soil and Water Conservation Districts of Allen, Dekalb, and Noble counties were used to represent agricultural practices in the watershed which included the type of crops grown, tillage practices, fertilizer, and pesticide application rates. Model results were evaluated based on efficiency coefficient values, standard statistical measures, and visual inspection of the measured and simulated hydrographs. The Nash and Sutcliffe model efficiency coefficients (E(NS)) for monthly and daily stream flow calibration and validation ranged from 0.51 to 0.66. The E(NS) values for atrazine calibration and validation ranged from 0.43 to 0.59. All E(NS) values were within the range of acceptable model performance standards. The results of this study indicate that the model is an effective tool in capturing the dynamics of stream flow and atrazine concentrations on a large-scale agricultural watershed in the midwestern USA. PMID:17332256

This study focused on the input of hydrophilic biocides into the aquatic environment and on the efficiency of their removal in conventional wastewater treatment by a mass flux analysis. A fully automated method consisting of on-line solid phase extraction coupled to LC-ESI-MS/MS was developed and validated for the simultaneous trace determination of different biocidal compounds (1,2-benzisothiazoline-3-one (BIT), 3-Iodo-2-propynylbutyl-carbamate (IPBC), irgarol 1051 and 2-N-octyl-4-isothiazolinone (octhilinone, OIT), carbendazim, diazinon, diuron, isoproturon, mecoprop, terbutryn and terbutylazine) and pharmaceuticals (diclofenac and sulfamethoxazole) in wastewater and surface water. In the tertiary effluent, the highest average concentrations were determined for mecoprop (1010 ng/L) which was at comparable levels as the pharmaceuticals diclofenac (690 ng/L) and sulfamethoxazole (140 ng/L) but 1-2 orders of magnitude higher than the other biocidal compounds. Average eliminations for all compounds were usually below 50%. During rain events, increased residual amounts of biocidal contaminants are discharged to receiving surface waters. PMID:20663596

Fermented foods and beverages contain several different types of dipeptides, which are believed to be important components for taste. To date, however, a method for the comprehensive analysis of dipeptides in these products has not yet been established. In this study, comprehensive analysis of dipeptides in alcoholic beverages was performed by a high-resolution separation method based on the structural characteristics of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC)-derivatized dipeptides as well as dipeptide quantification and structural estimation using ultra-high-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and UHPLC-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOFMS), respectively. Dipeptide content was found to differ considerably among Japanese sake, beer, and wine; UHPLC-MS/MS analysis revealed that many types of dipeptides are present in sake. Dipeptide quantification analysis identified 32 types of dipeptides within the concentration range of 1.1-97.2 ?M in sake. The analysis was validated by dipeptide recovery of 64.0-107.2% (2.5 ?M of standard) with a relative standard deviation of ?33.2% from an actual alcoholic sample. Furthermore, UHPLC-Q-TOFMS analysis suggested the existence of more than 35 types of dipeptides in sake. Thus, by the combined analysis methods, we discovered that more than 60 dipeptides are present in sake. This research is the first report of dipeptide profiling of fermented alcoholic beverages by comprehensive analysis. PMID:22560451

Using several extraction methods including the QuEChERS approach, samples of both model and natural sediments were prepared. For the isolation of the target group of pesticides, two variants of two complementary extractions had to be used. Resulting extracts were analysed with LC/MS/MS. Selected methods furnishing the best results were validated in the terms of linearity and repeatability. Their limits of detection ranged from 0.1 to 2 ng/g, their limits of quantification from 1 to 6 ng/g and their recovery percentage varied between 46 % and 102 %. PMID:22481210

Plasmopara viticola, the causal agent of grapevine downy mildew, severely affects grape yield and wine quality worldwide. Biocontrol agents and resistance inducers could be valid alternatives to chemical pesticides. We demonstrated the capability of Trichoderma harzianum T39 to protect susceptible grapevine cultivars (Vitis vinifera cv. Pinot Gris and cv. Pinot Noir) against downy mildew under greenhouse conditions. T. harzianum T39 reduced downy mildew severity on grapevine without a direct inhibition of P. viticola sporangia germination. Plant-mediated resistance was activated after preventive T. harzianum treatments, in a manner similar to that observed for benzothiadiazole (BTH) elicitation. Optimal disease control results were seen when BTH was applied 24h before pathogen inoculation ...

Stemona spp. have been traditionally used as natural pesticides and medicinal plants. S. curtisii, a dominant species of south and southwest Thailand, attracted attention for its insecticidal properties caused by specific alkaloids. A HPLC analytical method for quantitative determination of the major derivatives oxystemokerrine, stemocurtisine, stemocurtisinol, and stemofoline in root extracts of S. curtisii was developed. The method was validated for its linearity, precision, accuracy, limit of detection (LOD) and limit of quantitation (LOQ). Ten root samples were collected from various localities in Thailand and investigated for their insecticidal activities against neonate larvae of Spodoptera littoralis. Stemofoline was shown to possess the highest insecticidal activity with a LC50 val...

Abstract Analytical potentiality of a modified version of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method has been studied and validated for the extraction of a group of 11 pesticides (ethoprophos, cadusafos, dimethoate, terbufos, disulfoton, chlorpyrifos-methyl, fenitrothion, pirimiphos-methyl, malathion, chlorpyrifos and fensulfothion) and some of their metabolites (malaoxon, disulfoton sulfoxide, terbufos sulfone and disulfoton sulfone) in toasted barley and chickpea flours. The method involves separation and quantification by gas chromatography (GC) with nitrogen phosphorus detection (NPD) using triphenylphosphate as the internal standard. Matrix-matched calibration was carried out for both flours due to the existence of a matrix effect. Linearity, recovery, precis...

A new analytical method for the determination of 14 pesticide residues in fresh peppermint was developed based on the QuEChERS sample preparation technique followed by gas chromatography coupled to electron capture and nitrogen phosphorus detectors (GC/ECD/NPD). The validation study clearly demonstrated suitability of the method for its intended application. The overall recoveries of the pesticides from peppermint, at the three spiking levels of 0.01, 0.1 and 1.0 mg kg(-1), were 100% ± 10% with relative standard deviations of 6% ± 5% on average. The limit of quantification was 0.01 mg kg(-1) for all the pesticides. The expanded uncertainties were in the range between 7% and 30% (14% on average), which was distinctively less than a maximum default value of ±50%. Compared with our previous method, that entailed dichloromethane/acetone extraction and florisil column cleanup with collection of four fractions, the new method was more straightforward, less time and labour intensive as well as more sensitive, selective and accurate, simultaneously. PMID:22752220

A method for the detection and quantification of 16 pesticides: flufenoxuron, fenoxycarb, dimethomorph, acetamiprid, imidacloprid, lufenuron, thiacloprid, thiabendazole, thiophanate-methyl, spinosad, fenbutatin oxide, methoxyfenozide, oxamyl, clothianidin, thiamethoxam and carbendazim has been developed based on high-performance liquid chromatography-mass spectrometry. Pesticide residues were extracted from the samples according to the QuEChERS method which stands for quick, essay, cheap, effective, rugged and safe. Homogenised analytical portions (10 g ± 0.1) of samples of peppers were spiked at two levels (10 and 100 ?g kg?¹) with a small volume of an appropriate standard mixture solution containing each pesticide. Analyses were performed using electrospray ionization (ESI) and a MSD trap system. Chromatography separation was achieved using a ZORBAX SB-C18 3.5 ?m particle size analytical column, 2.1 × 50 mm from Agilent, with gradient elution at a flow-rate of 0.4 mL/min with mobile phases: waters-0.1 % HCOOH-5 mM HCOONH? and MeOH-5 mM HCOONH?. The method has been validated based on the SANCO European Guidelines. Under the optimized conditions the recoveries (n = 7) were in the range 70-110 % with satisfactory precision (CV ? 20 %). A linear dynamic range was obtained over a range of concentrations from 10 to 100 ?g kg?¹ for each of the analytes, with correlation coefficients >0.997. PMID:21726151

An extraction and analytical method for the determination of pesticide residues in fruits and vegetables has been developed. The method includes extraction with a pressurised liquid solvent containing a mixture of 1,1,1,2-tetrafluoroethane and toluene, and identification/quantification of pesticides using ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UPLC/MS/MS). Validation studies were carried out to evaluate the performance of the method for the determination of 71 different pesticides and metabolites in tomato, cucumber, pepper, spinach, zucchini, grape, cherry, peach and apricot. Matrix-matched calibration curves were applied and correlation coefficients (r(2)) came out to be greater than 0.99. Limit of quantification (LOQ) values of the active substances were found to be lower than the maximum residue limits (MRL) according to regulations in Turkey. The recovery values were found to be between 70% and 120% with relative standard deviations less than 20%. Based on these results, the proposed method is fast, cheaper, rugged and gives quantitative results with no additional clean-up steps. PMID:22953939

An alternative method has been developed to determine more than 50 pesticides in alcoholic beverages using hollow fibre liquid phase microextraction (HF-LPME) followed by ultra-high pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), without any further clean-up step. Pesticides were extracted from the sample to the organic solvent immobilized in the fibre and they were desorbed in methanol prior to chromatographic analysis. Experimental parameters related to microextraction such as type of organic solvent, extraction time and agitation rate have been optimized. The extraction method has been validated for several types of alcoholic beverages such as wine and beer, and no matrix effect was observed. The technique requires minimal sample handling and solvent consumption. Using optimum conditions, low detection limits (0.01-5.61microgL(-1)) and good linearity (R(2)>0.95) were obtained. Repeatability and interday precision ranged from 3.0 to 16.8% and from 5.9 to 21.2%, respectively. Finally the optimized method was applied to real samples and carbaryl, triadimenol, spyroxamine, epoxiconazole, triflumizol and fenazaquin were detected in some of the analyzed samples. The obtained results indicated that the new method can be successfully applied for extraction and determination of pesticides in alcoholic beverages, increasing sample throughput. PMID:18762301

An adult vial test was used to determine the contact toxicity of several technical insecticides comprised of synthetic pyrethroids, organophosphates, neonicotinoids and carbamates to cotton fleahopper, Pseudatomoscelis seriatus (Reuter). Among the synthetic pyrethroids, bifenthrin was most toxic to ...

The solution was effected by the choice of a sintered nickel electrode to replace the .... The precipitate, a metal carbamate, was a curing agent was used in the ... The city water was filtered through particulate filters, charcoal filters, and two ...

...the document by docket ID number and other identifying information (subject heading, Federal...o-tolyl] carbamate (BF 500-3); expressed as parent compound, in or on sugarcane, cane at 0.2 ppm. No...

A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3-N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pestic...

Cholesterol-appended benzothiadiazole fluorescent dyes were self-assembled to form aggregates through van der Waals interactions among the cholesterol moieties, hydrogen-bonding interactions among the carbamate moieties, and ?-stacking interactions among the benzothiadiazole moieties.   

When humans serve as inadvertent intermediate hosts for Echinococcus multilocularis, disease (alveolar echinococcosis [AE]) may result from the expanding parasite metacestode in visceral organs, mostly in the liver. Benzimidazole carbamate derivatives such as mebendazole and albendazole are used for...

Abstract in portuguese OBJETIVO: Descrever o perfil dos casos de intoxicações exógenas de crianças admitidas em hospitais de emergência da região metropolitana do Rio de Janeiro, durante três anos. MÉTODOS: Realizou-se levantamento dos dados a partir dos boletins de atendimento de emergência, tendo sido identificados os casos suspeitos ou confirmados de intoxicação nas seguintes categorias: drogas, medicamentos e substâncias biológicas; solventes orgânicos e hidrocarbonetos haloge (more) nados; produtos químicos; monóxido de carbono e outros gases, fumaças e vapores; e pesticidas. RESULTADOS: Foram registrados 1.574 casos de intoxicação entre crianças até cinco anos de idade, sendo que cerca de 40% dos casos envolveu produtos químicos de uso doméstico, 35% os medicamentos, e 15% algum tipo de pesticida. Mais da metade das intoxicações por pesticidas envolveu o chumbinho, um produto ilegalmente vendido como raticida, que frequentemente contém o agrotóxico carbamato. A distribuição dos agentes envolvidos variou significativamente segundo sexo, sendo a frequência relativa das intoxicações por medicamentos e chumbinho maior no sexo feminino em comparação ao masculino. Observou-se que a participação dos produtos químicos de uso doméstico decresceu com a idade, enquanto aumentou a dos medicamentos como agentes da intoxicação. No período analisado não observou-se redução significativa no número total de casos registrados anualmente. CONCLUSÃO: Fortalecer a rede de Centros de Controle de Intoxicações, intervir na linha de produção de embalagens para medicamentos e produtos químicos, aumentar a fiscalização sobre a comercialização ilegal do chumbinho, e enfatizar atividades de educação em saúde são ações que podem contribuir para mudar este panorama. Abstract in english OBJECTIVE: To describe the profile of poisoning cases among children attended during three years at emergency hospitals in the metropolitan area of Rio de Janeiro, Brazil. METHODS: All confirmed or suspected poisoning cases, due to drugs and biological substances; organic solvents and hydrocarbons; chemical products; carbon monoxide and other gases; and pesticides, were collected. RESULTS: 1,574 cases of poisoning in children up to 5 years of age were detected. Around 40% (more) of the cases involved chemical products of domestic use, 35% were caused by drugs, and 15% by pesticides. More than half of pesticide poisonings involved the "chumbinho", an illegal product sold as a rodenticide, and usually including in its formulation a carbamate. Distribution of agents varied significantly by gender, the relative frequency of poisonings due to drugs and "chumbinho" being higher among females than males. Participation of chemical products of domestic use decreased with age, but the role of drugs increased as agents of poisoning. During the observation period there was no significant reduction in the total number of annual cases. CONCLUSION: Supporting the expansion of the network of Poison Control Centers, developing intervention for the production of safer packaging devices for drugs chemical products, suppressing the illegal commerce of "chumbinho", and fostering health education activities might contribute to modify this situation.

... herbal dietary supplements for the presence of lead, arsenic, mercury, cadmium, organichlorine pesticides, and organophosphorous pesticides. Certain ... those, 32 also contained mercury, 28 cadmium, 21 arsenic, and 18 residues from at least one pesticide. ...

The rates and pathways for pesticide transformation under drinking water treatment conditions are known for only a few pesticides and only under limited conditions. For example, it is known that chlorine reacting with organophosphate (OP) pesticides that contain the thiophosphate...

...Commission: Codex Committee on Pesticide Residues (CCPR) AGENCY: Office of...Session of the Codex Committee on Pesticide Residues (CCPR) of the Codex Alimentarius...establishing maximum limits for pesticide residues in specific food items or...

...FRL-9364-3] Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...July 25, 2012, concerning Pesticide Petition (PP) 2F8026...establish tolerances for residues of the herbicide...

...amendment of regulations for residues of pesticide chemicals in or on various...regulation in 40 CFR part 180 for residues of pesticide chemicals in or on various...modification of regulations for residues of pesticides in or on food various...