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Dermal absorption of pesticides in the rat.

The Office of Pesticide Programs (OPP) of the Environmental Protection Agency has developed a standard protocol for evaluating the dermal penetration of pesticides in the rat. This protocol was formalized in 1994 as a guideline for Dermal Absorption Studies of Pesticides. To date, in excess of 263 studies on the dermal absorption of over 160 pesticide chemicals have been submitted to OPP as part of the pesticide registration and risk assessment processes. The majority of these studies has been performed according to the OPP standard protocol in the rat. These studies constitute the largest database in existence on the dermal absorption of a wide variety of chemicals using a standard protocol. From this standard protocol it is possible to describe, quantitatively with dose and time, the entrance of a chemical into and penetration through the mammalian epidermis into the systemic circulation, its concentration in blood and in the body, and its excretion in urine and feces. This article describes the experimental design of the standard protocol and presents examples of the types of pesticides studied: pesticides that are neither volatile nor damage the skin (the most common type), volatile pesticides, and pesticides that damage the skin. Examples are selected to illustrate differences in the pattern of dermal uptake and subsequent absorption into the systemic compartment among and within the three classes.

Animals↗

Effect of organophosphorus and organochlorine pesticides (monochrotophos, chlorpyriphos, dimethoate, and endosulfan) on human lymphocytes in-vitro.

The toxicological profile of the four pesticides described herein characterizes its effects on lymphocytes from peripheral blood from healthy donors. The exposure to all pesticides was by direct interaction/incubation with varying concentrations of the pesticide with blood sample in-vitro. The dose response relationship in each case was calculated by applying log tables as LC50 values. Cytotoxicity of these pesticides on lymphocytes was measured using the trypan blue dye exclusion technique. Based on LC50 value, all the four pesticides were found to be highly toxic to lymphocyte culture, among them, monocrotophos and endosulfan were the most toxic and dimethoate was the least toxic. The genotoxicity of the pesticides was also determined by comet assay. The results revealed that the pesticides caused increase in the tail length indicating DNA damage. This study suggests that these pesticides have the capacity to alter the genetic material particularly chromosomes in mammalian cultures. The comet assay used in this study was found to be a sensitive and rapid method to detect genotoxicity of pesticide compounds.

Cells, Cultured↗

Pesticide use and breast cancer risk among farmers' wives in the agricultural health study.

The authors examined the association between pesticide use and breast cancer incidence among farmers' wives in a large prospective cohort study in Iowa and North Carolina. Participants were 30,454 women with no history of breast cancer prior to cohort enrollment in 1993-1997. Information on pesticide use and other information was obtained by self-administered questionnaire at enrollment from the women and their husbands. Through 2000, 309 incident breast cancer cases were identified via population-based cancer registries. Rate ratios were calculated for individual pesticides using Poisson regression, controlling for confounding factors. Breast cancer standardized incidence ratios were 0.87 (95% confidence interval: 0.74, 1.02) for women who reported ever applying pesticides and 1.05 (95% confidence interval: 0.89, 1.24) for women who reported never applying pesticides. There was some evidence of increased risk associated with use of 2,4,5-trichloro-phenoxypropionic acid (2,4,5-TP) and possibly use of dieldrin, captan, and 2,4,5-trichlorophenoxyacetic acid (2,4,5-TP), but small numbers of cases among those who had personally used the pesticides precluded firm conclusions. The authors found no clear association of breast cancer risk with farm size or washing of clothes worn during pesticide application, but risk was modestly elevated among women whose homes were closest to areas of pesticide application. Further follow-up of this cohort should help clarify the relation between pesticide exposure and breast cancer risk.

Adolescent↗

Pesticide exposure and self-reported Parkinson's disease in the agricultural health study.

Previous studies based on limited exposure assessment have suggested that Parkinson's disease (PD) is associated with pesticide exposure. The authors used data obtained from licensed private pesticide applicators and spouses participating in the Agricultural Health Study to evaluate the relation of self-reported PD to pesticide exposure. Cohort members, who were enrolled in 1993-1997, provided detailed information on lifetime pesticide use. At follow-up in 1999-2003, 68% of the cohort was interviewed. Cases were defined as participants who reported physician-diagnosed PD at enrollment (prevalent cases, n = 83) or follow-up (incident cases, n = 78). Cases were compared with cohort members who did not report PD (n = 79,557 at enrollment and n = 55,931 at follow-up). Incident PD was associated with cumulative days of pesticide use at enrollment (for highest quartile vs. lowest, odds ratio (OR) = 2.3, 95% confidence interval: 1.2, 4.5; p-trend = 0.009), with personally applying pesticides more than half the time (OR = 1.9, 95% confidence interval: 0.7, 4.7), and with some specific pesticides (ORs > or = 1.4). Prevalent PD was not associated with overall pesticide use. This study suggests that exposure to certain pesticides may increase PD risk. Findings for specific chemicals may provide fruitful leads for further investigation.

Adolescent↗

Myths, models and mitigation of resistance to pesticides.

Resistance to pesticides in arthropod pests is a significant economic, ecological and public health problem. Although extensive research has been conducted on diverse aspects of pesticide resistance and we have learned a great deal during the past 50 years, to some degree the discussion about 'resistance management' has been based on 'myths'. One myth involves the belief that we can manage resistance. I will maintain that we can only attempt to mitigate resistance because resistance is a natural evolutionary response to environmental stresses. As such, resistance will remain an ongoing dilemma in pest management and we can only delay the onset of resistance to pesticides. 'Resistance management' models and tactics have been much discussed but have been tested and deployed in practical pest management programmes with only limited success. Yet the myth persists that better models will provide a 'solution' to the problem. The reality is that success in using mitigation models is limited because these models are applied to inappropriate situations in which the critical genetic, ecological, biological or logistic assumptions cannot be met. It is difficult to predict in advance which model is appropriate to a particular situation; if the model assumptions cannot be met, applying the model sometimes can increase the rate of resistance development rather than slow it down. Are there any solutions? I believe we already have one. Unfortunately, it is not a simple or easy one to deploy. It involves employing effective agronomic practices to develop and maintain a healthy crop, monitoring pest densities, evaluating economic injury levels so that pesticides are applied only when necessary, deploying and conserving biological control agents, using host-plant resistance, cultural controls of the pest, biorational pest controls, and genetic control methods. As a part of a truly multi-tactic strategy, it is crucial to evaluate the effect of pesticides on natural enemies in order to preserve them in the cropping system. Sometimes, pesticide-resistant natural enemies are effective components of this resistance mitigation programme. Another name for this resistance mitigation model is integrated pest management (IPM). This complex model was outlined in some detail nearly 40 years ago by V. M. Stern and colleagues. To deploy the IPM resistance mitigation model, we must admit that pest management and resistance mitigation programmes are not sustainable if based on a single-tactic strategy. Delaying resistance, whether to traditional pesticides or to transgenic plants containing toxin genes from Bacillus thuringiensis, will require that we develop multi-tactic pest management programmes that incorporate all appropriate pest management approaches. Because pesticides are limited resources, and their loss can result in significant social and economic costs, they should be reserved for situations where they are truly needed--as tools to subdue an unexpected pest population outbreak. Effective multi-tactic IPM programmes delay resistance (= mitigation) because the number and rates of pesticide applications will be reduced.

Animals↗

Federal and state pesticide regulations and legislation.

The combined research, education, and regulatory efforts of federal and state governments have made possible an impressive record of abundant production while imposing minimal harm to human health and the environment. Considering that approximately one billion pounds of pesticides are being applied in the United States annually to control about 2000 pest species, the safety record is remarkable. The increased public concern about environmental values and long-term health effects is constructive and is resulting in some of the regulatory changes discussed in this article. The Federal Environmental Pesticide Control Act can result in an improved and expanded joint effort by federal and state governments to limit the misuse of pesticides while permitting their use to facilitate increased production of food, feed, and fiber; provide protection from spoilage; improve health; and control nuisance insects and unwanted plants. Implementation of current regulations, plus those in the process of being enacted under authority of the new federal act, will be complex and costly. Regulations will control the registration, labeling, distribution, storage, use and application, and disposal of pesticides. A small segment of our society would like to have the use of all chemicals banned. A few individuals oppose all government controls. However, the vast majority of agricultural producer groups, representatives of industry, and the public support the need for pesticide regulations. Only through continued legal controls over pesticides may we hope to retain their use. Our society has gained tremendous benefits from the use of pesticides to prevent disease and to increase the production of food and fiber. Our need to use pesticides will continue to increase for the foreseeable future. Government agencies responsible for protecting human health and the environment must make sound judgments on an individual basis in evaluating the evidence concerning both the benefits and risks of using pesticides.

Government Agencies↗

Identifying constituents to participate in a project to control pesticide exposure in children of farmworkers.

Farmers in Washington State use pesticides to control harmful pests that might interfere with the quality of their products. Farmworkers, who are primarily responsible for thinning, harvesting, and other agricultural work, are often exposed to these pesticides and take home pesticide residues on their clothing, shoes, and skin, potentially exposing children in the household to pesticides. We designed a project to reduce children's exposure by using a community organization model. To better understand the community views regarding pesticide exposure, we conducted a qualitative community analysis. Two methods of data gathering were used to collect information. Individual interviews were conducted with some respondents, and small group discussions were held with others. Analysis indicated wide disparity among involved groups in their views on pesticides; however, a number of themes common to the majority of the constituents were identified and discussed with a community planning group. Because of the contention around pesticides, the group recommended every constituent participate in decision making. The group noted it was important to emphasize that the research project could provide scientific information on pesticide exposure to everyone in the Lower Yakima Valley. Our study demonstrates both the widely varying views of different constituents around the issue of pesticide exposure and common themes that can form the basis for collaboration and consensus on approaching the issue.

Adolescent↗

Developing a comprehensive pesticide health effects tracking system for an urban setting: New York City's approach.

In recent years, there have been substantial investments and improvements in federal and state surveillance systems to track the health effects from pesticide exposure. These surveillance systems help to identify risk factors for occupational exposure to pesticides, patterns in poisonings, clusters of disease, and populations at risk of exposure from pesticide use. Data from pesticide use registries and recent epidemiologic evidence pointing to health risks from urban residential pesticide use make a strong case for understanding better the sale, application, and use of pesticides in cities. In this article, we describe plans for the development of a pesticide tracking system for New York City that will help to elucidate where and why pesticides are used, potential risks to varied populations, and the health consequences of their use. The results of an inventory of data sources are presented along with a description of their relevance to pesticide tracking. We also discuss practical, logistical, and methodologic difficulties of linking multiple secondary data sources with different levels of person, place, and time descriptors.

Data Collection↗

The tobacco industry and pesticide regulations: case studies from tobacco industry archives.

Tobacco is a heavily pesticide-dependent crop. Because pesticides involve human safety and health issues, they are regulated nationally and internationally; however, little is known about how tobacco companies respond to regulatory pressures regarding pesticides. In this study we analyzed internal tobacco industry documents to describe industry activities aimed at influencing pesticide regulations. We used a case study approach based on examination of approximately 2,000 internal company documents and 3,885 pages of U.S. Environmental Protection Agency documents obtained through Freedom of Information Act requests. The cases involved methoprene, the ethylene bisdithiocarbamates, and phosphine. We show how the tobacco industry successfully altered the outcome in two cases by hiring ex-agency scientists to write reports favorable to industry positions regarding pesticide regulations for national (U.S. Environmental Protection Agency) and international (World Health Organization) regulatory bodies. We also show how the industry worked to forestall tobacco pesticide regulation by attempting to self-regulate in Europe, and how Philip Morris encouraged a pesticide manufacturer to apply for higher tolerance levels in Malaysia and Europe while keeping tobacco industry interest a secret from government regulators. This study suggests that the tobacco industry is able to exert considerable influence over the pesticide regulatory process and that increased scrutiny of this process and protection of the public interest in pesticide regulation may be warranted.

Conflict of Interest↗

Neurologic symptoms in licensed private pesticide applicators in the agricultural health study.

Exposure to high levels of many pesticides has both acute and long-term neurologic consequences, but little is known about the neurotoxicity of chronic exposure to moderate levels of pesticides. We analyzed cross-sectional data from 18,782 white male licensed private pesticide applicators enrolled in the Agricultural Health Study in 1993-1997. Applicators provided information on lifetime pesticide use and 23 neurologic symptoms typically associated with pesticide intoxication. An indicator of more symptoms (> or = 10 vs. < 10) during the year before enrollment was associated with cumulative lifetime days of insecticide use: odds ratios (95% confidence intervals) were 1.64 (1.36-1.97) for 1-50 days, 1.89 (1.58-2.25) for 51-500 days, and 2.50 (2.00-3.13) for > 500 days, compared with never users. A modest association for fumigants [> 50 days, 1.50 (1.24-1.81)] and weaker relationships for herbicides [> 500 days, 1.32 (0.99-1.75)] and fungicides [> 50 days, 1.23 (1.00-1.50)] were observed. Pesticide use within the year before enrollment was not associated with symptom count. Only associations with insecticides and fumigants persisted when all four pesticide groups were examined simultaneously. Among chemical classes of insecticides, associations were strongest for organophosphates and organochlorines. Associations with cumulative exposure persisted after excluding individuals who had a history of pesticide poisoning or had experienced an event involving high personal pesticide exposure. These results suggest that self-reported neurologic symptoms are associated with cumulative exposure to moderate levels of fumigants and organophosphate and organochlorine insecticides, regardless of recent exposure or history of poisoning.

Adolescent↗

Workplace, household, and personal predictors of pesticide exposure for farmworkers.

In this article we identify factors potentially associated with pesticide exposure among farmworkers, grade the evidence in the peer-reviewed literature for such associations, and propose a minimum set of measures necessary to understand farmworker risk for pesticide exposure. Data sources we reviewed included Medline, Science Citation Index, Social Science Citation Index, PsycINFO, and AGRICOLA databases. Data extraction was restricted to those articles that reported primary data collection and analysis published in 1990 or later. We read and summarized evidence for pesticide exposure associations. For data synthesis, articles were graded by type of evidence for association of risk factor with pesticide exposure as follows: 1 = association demonstrated in farmworkers; 2 = association demonstrated in nonfarmworker sample; 3 = plausible association proposed for farmworkers; or 4 = association plausible but not published for farmworkers. Of more than 80 studies we identified, only a third used environmental or biomarker evidence to document farmworker exposure to pesticides. Summaries of articles were compiled by level of evidence and presented in tabular form. A minimum list of data to be collected in farmworker pesticide studies was derived from these evidence tables. Despite ongoing concern about pesticide exposure of farmworkers and their families, relatively few studies have tried to test directly the association of behavioral and environmental factors with pesticide exposure in this population. Future studies should attempt to use similar behavioral, environmental, and psychosocial measures to build a body of evidence with which to better understand the risk factors for pesticide exposure among farmworkers.

Agriculture↗

[Rural work and risk factors associated with pesticide use in Minas Gerais, Brazil].

This paper aimed to characterize the rural work process in nine counties in Minas Gerais State, considering socio-demographic indicators, the land tenure structure of farm operations, and work practices related to pesticide use and poisoning Data were obtained through the Jorge Duprat Figueiredo Foundation for Workers' Safety and Occupational Medicine, which applied a questionnaire to 1,064 rural workers from 1991 to 2000. Through a logistic regression, risk factors associated with pesticide poisoning were obtained for the carbamate and organophosphate groups. Some 50% of interviewees displayed at least moderate pesticide toxicity. Risk factors for pesticide poisoning were: last contact with pesticides less than two weeks before the blood cholinesterase test; no use of personal protective equipment by workers applying pesticides; having received instructions from the pesticide salesperson; report of carbamates/organophosphates as the main pesticides used; and working in the counties of Te foli Otoni, Guidoval, or Piraúba. The results emphasize the high level of health risk associated with pesticide use among these rural workers.

Adolescent↗

Toxicity of pesticides to aquatic microorganisms: a review.

Microorganisms contribute significantly to primary production, nutrient cycling, and decomposition in estuarine eco-systems; therefore, detrimental effects of pesticides on microbial species may have subsequent impacts on higher trophic levels. Pesticides may affect estuarine microorganisms via spills, runoff, and drift. Both the structure and the function of microbial communities may be impaired by pesticide toxicity. Pesticides may also be metabolized or bioaccumulated by microorganisms. Mechanisms of toxicity vary, depending on the type of pesticide and the microbial species exposed. Herbicides are generally most toxic to phototrophic microorganisms, exhibiting toxicity by disrupting photosynthesis. Atrazine is the most widely used and most extensively studied herbicide. Toxic effects of organophosphate and organochlorine insecticides on microbial species have also been demonstrated, although their mechanisms of toxicity in such nontarget species remain unclear. There is a great deal of variability in the toxicity of even a single pesticide among microbial species. When attempting to predict the toxicity of pesticides in estuarine ecosystems, effects of pesticide mixtures and interactions with nutrients should be considered. The toxicity of pesticides to aquatic microorganisms, especially bacteria and protozoa, is an area of research requiring further study.

Animals↗

TurfPQ, a pesticide runoff model for turf.

Environmental assessments of golf courses and other turf systems must often rely on mathematical modeling. However, in the case of pesticide runoff, successful modeling applications are rare. Available models were developed for agricultural applications and have seen very limited testing for turf. TurfPQ is a pesticide runoff model developed exclusively for turf. The model is based on a curve number calculation for runoff volume and linear partitioning of pesticide into adsorbed and dissolved components during a precipitation or irrigation event. Calibration is optional, so the model can be applied, using default parameter values, to situations where runoff and chemical loss data are unavailable. TurfPQ was tested with default parameter values for 52 pesticide runoff events involving six pesticides measured in plot studies in four states. The model typically produced conservative overpredictions of pesticide runoff, particularly with strongly adsorbed pesticides. Mean predicted pesticide runoff was 2.9% [corrected] of application, compared with an observed mean of 2.1%. TurfPQ captured the dynamics of the pesticide runoff events well with R2 = 0.65 [corrected]. Sensitivity analyses indicated that prediction errors could be reduced by better estimates of adsorption parameters and runoff curve numbers. However, even with default parameters, TurfPQ predictions are at least as accurate as those produced by more complex models.

Adsorption↗

Turfgrass thatch effects on pesticide leaching: a laboratory and modeling study.

Process-based models are frequently used to assess the water quality impacts of turfgrass management emanating from proposed or existing golf courses. Thatch complicates the prediction of pesticide transport because surface-applied pesticides must pass through an organic-rich layer before entering the soil. This study was conducted to (i) compare the use of a linear equilibrium model (LEM) and two-site nonequilibrium (2SNE) model to predict pesticide transport through soil and thatch + soil columns, and (ii) evaluate thatch effects on pesticide transport through soil columns with a volume-averaging approach. Pesticide breakthrough curves were obtained for soil and thatch + soil columns from a 1 cm h(-1) flux applied one day after applying triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) and carbaryl (1-napthyl-methyl carbamate). Pesticide and bromide transport parameters indicated that nonequilibrium processes were affecting pesticide transport. Columns containing zoysiagrass (Zoysia japonica Steud.) thatch had lower triclopyr and carbaryl leaching losses than did soil-only columns, although total reductions attributable to thatch did not exceed 15% of the applied pesticide. When laboratory-based retardation factors were used, the 2SNE model explained 88 to 93% of the variability for triclopyr and 70 to 94% of the variability for carbaryl. Laboratory-based retardation factors performed well in a 2SNE model to predict the peak concentration and tailing behavior of triclopyr and carbaryl with a volume-averaging approach. These results suggest that separate representation of the thatch layer in process-based models is not a prerequisite to obtain reasonable estimates of pesticide transport under steady state flow conditions.

Environment Design↗

[Multiresidue analysis of nitrogen-containing and sulfur-containing pesticides in agricultural products using dual-column GC-NPD/FPD].

We investigated simultaneous analytical methods for pesticide residues in large numbers of agricultural products samples. Extraction of each sample with acetonitrile was followed by a salting-out step using a graduated cylinder. The test solution was cleaned up with gel permeation chromatography (GPC), which separated the pesticide eluate into 2 fractions, and then with a tandem mini-column. Analysis was done with a dual-column GC equipped with a dual NPD and FPD (S mode) detector. Use of the Siltek-deactivated liner, guard column, and Y connector, and Silcosteel-treated NPD jet was effective for preventing the breakdown of sulfur-containing pesticides. Recoveries of 87 nitrogen-containing and sulfur-containing pesticides from fortified spinach, tomato, apple, strawberry and brown rice, ranged from 71 to 127% with RSD values of 1-24%, except for recoveries of aldicarb, amitraz, ethiofencarb, imazalil, propamocarb and triflumizole. Detection limits of pesticides were very good (0.3-5 ppb (NPD) and 2-20 ppb (FPD)) for routine analysis of pesticide residues in foods. Surveillance of pesticides in agricultural products was carried out by using the present method. From 22 out of 33 samples, 21 pesticides (43 in total) were detected. The results indicated that the present method can be applied as an efficient and reliable means for monitoring pesticide residues in agricultural products.

Chromatography, Gas↗

[Applicability of GC, GC/MS and liquid chromatography with tandem mass spectrometry to screening for 140 pesticides in agricultural products].

The applicability of GC, GC/MS and liquid chromatography with tandem mass spectrometry (LC/MS/MS) to screening for 140 pesticides in agricultural products was examined. Validation of multi-residue screening methods for the determination of 88 pesticides in 12 crops (asparagus, cauliflower, burdock, carrot, broccoli, spinach, matsutake mushroom, orange, soybean, sesame, millet and tea) was done by GC and GC/MS. Of the 88 pesticides, 63 were obtained with recoveries in the range from 50 to 150% at the 0.1 microg/g level in the 12 crops. Applicability of the official methods in Japan to 74 pesticides, including 22 pesticides with low recovery (< 50%) by GC or GC/MS analysis, was also examined by LC/MS/MS. LC/MS/MS acquisition parameters were established for 67 pesticides in positive and negative electrospray ionization (ESI) modes. Of 67 pesticides validated in 7 crops using LC/MS/MS at the 0.1 microg/g level, 44 showed recoveries in the range from 50 to 150%. The occurrence of matrix interference in LC/MS/MS can lead to false-positive detection of MCPA in spinach, cabbage and orange and false-negative detection of four pesticides in orange, spinach, apple and unpolished rice. Good linearity was observed in the studied ranges by GC, GC/MS (r > 0.990) and LC/MS/MS (r > 0.995). Of the total of 140 pesticides validated by GC, GC/MS and LC/MS/MS, 107 were newly recognized as suitable subjects for screening.

Chromatography, Gas↗

Kuwait's total diet study: dietary intake of organochlorine, carbamate, benzimidazole and phenylurea pesticide residues.

The State of Kuwait in cooperation with the U.S. Food and Drug Administration (FDA) conducted a Total Diet Study (TDS) to estimate intakes of pesticide residues by the population. The levels of organochlorine (OC) pesticides, carbamates, benzimidazoles, and phenylureas in the TDS core list are reported here. The TDS core list was established through a national food consumption survey. All food items (140 for the Kuwaiti adult) were prepared as eaten and analyzed for the pesticides mentioned above. The FDA's multiresidue methods in Volume I of the Pesticide Analytical Manual were used in gas, liquid, and gel permeation chromatographic analyses. Only vegetable and fruit samples contained pesticide residues (mg/kg), including the carbamates 1-naphthol (1.4) and 3H-carbofuran (0.94) in carrots; the OC pesticide vinclozolin (0.47), 3H-carbofuran (0.66), and fenuron (0.6) in kiwi fruit; the OC pesticide procymidone (0.32) and carbendazim (0.5) in grapes; 3H-carbofuran (5.0) in apricots; the OC pesticides captan (0.013) and thiabendazole (0.63) in pears; captan (0.035) in plums; and carbendazim (0.4) in mandarin oranges. The levels of 3H-carbofuran found in both apricots and kiwi fruit exceeded the maximum residue limits (MRLs) of the Food and Agriculture Organization/World Health Organization (FAO/WHO) of the United Nations. The daily intakes of pesticides by the different population groups are discussed in light of the FAO/WHO acceptable daily intakes.

Benzimidazoles↗