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PubMed2004

Degradation and leaching potential of pesticides in biobed systems.

Biobeds provide a potential solution to pesticide contamination of surface waters arising from the farmyard. Previous work has shown that biobeds can effectively treat spills and splashes of pesticide. This study investigated the potential for biobeds to treat much larger volumes and amounts of pesticide waste not only arising from spills but also from washing processes. Two systems were assessed using a range of pesticides at the semi-field scale, ie a lined biobed system and an unlined system. Studies using the lined biobeds demonstrated that water management was crucial, with biobeds needing to be covered to exclude rain-water. Once covered, the top of the biobed became hydrophobic, restricting moisture loss and resulting in saturated conditions at depth. The drying out of the top layer coincided with a measured decrease in microbial biomass in the treated biobeds. Applied pesticides were effectively retained within the 0-5 cm layer. Whilst all pesticides tested degraded, low moisture content and microbial activity meant degradation rates were low. Studies using unlined biobeds showed that only the most mobile pesticides leached, and for these > 99% was removed by the system, with a significant proportion degraded within 9 months. Peak concentrations of the two most mobile pesticides did however exceeded the limits that are likely to be required by regulatory bodies. However, it is thought that these limits could be reached by optimisation of the system.

Biodegradation, Environmental↗
PubMed1989

Pesticides and food safety.

This report reviews recent developments regarding the environmental, toxicological, and regulatory issues surrounding pesticide residues in food. Factors affecting the establishment of regulatory limits are discussed. Pesticides monitored by state and federal agencies are compiled and the need for improvements in analytical techniques and enforcement procedures in governmental monitoring programs is pointed out. Specific incidents of concern related to pesticides in food including EDB in grain and grain products, aldicarb in watermelon, demeton-methyl in wine, DDT in fish, S,S,S-tributylphosphorotrithioate in chili peppers, and daminozide in apples and processed apple products are described. The National Academy of Science's study on the Environmental Protection Agency's (EPA) method for setting tolerances for pesticide residues is discussed, especially the dietary cancer risk estimates from pesticides and the inconsistencies in regulating oncogenic pesticides in raw and processed foods existing under the Delaney Clause. The EPA's Tolerance Assessment System is identified to improve the quality of the tolerance establishment process. New California laws to ensure food safety include mandated activities in identifying the toxicological data gaps for pesticides and evaluating pesticide tolerances. Already initiated, tighter regulatory activities at both the federal and the state levels are expected to improve scientific information development, regulatory decisions, and public health protection.

Food Analysis↗
PubMed1998

An indicator of pesticide environmental impact based on a fuzzy expert system.

Pesticide use options available to farmers differ strongly with respect to the risks they pose to the environment. This paper proposes a fuzzy expert system to calculate an indicator "Ipest" which reflects an expert perception of the potential environmental impact of the application of a pesticide in a field crop. We defined four modules, one reflecting the presence (rate of application) of the pesticide, the other three reflecting the risk for three major environmental compartments (groundwater, surface water, air). The input variables for these modules are pesticide properties, site-specific conditions and characteristics of the pesticide application. For each input variable two functions describing membership to the fuzzy subsets Favourable (F) and Unfavourable (U) have been defined. These functions are based on criteria drawn from the literature or on the authors' expert judgment. The expert system calculates the value of modules according to the degree of membership of the input variables to the fuzzy subsets F and U and according to sets of decision rules. The four modules can be considered individually or can be aggregated (again according to membership to fuzzy subsets F and U and a set of decision rules) into the indicator Ipest. The system is flexible and can be turned to expert perception, it can be used as a decision aid tool to rank or choose between alternative pesticide application options with respect to their potential environmental impact. Results of a sensitivity analysis and module and Ipest scores for some pesticide application cases are presented. An agro-ecological indicator IPEST, based on the expert system, is proposed as a tool to assess the environmental impact of all pesticide applications related to a crop within a year. The practical implementation of the expert system and its validation are discussed.

Biodegradation, Environmental↗
PubMed2004

Analysis of pesticides in honey by solid-phase extraction and gas chromatography-mass spectrometry.

An analytical method for the simultaneous determination of 51 pesticides in commercial honeys was developed. Honey (10 g) was dissolved in water/methanol (70:30; 10 mL) and transferred to a C(18) column (1 g) preconditioned with acetonitrile and water. Pesticides were subsequently eluted with a hexane/ethyl acetate mixture (50:50) and determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM). Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. Pesticides were confirmed by their retention times, their qualifier and target ions, and their qualifier/target abundance ratios. Recovery studies were performed at 0.1, 0.05, and 0.025 microg/g fortification levels for each pesticide, and the recoveries obtained were >86% with relative standard deviations of <10%. Good resolution of the pesticide mixture was achieved in approximately 41 min. The detection limits of the method ranged from 0.1 to 6.1 microg/kg for the different pesticides studied. The developed method is linear over the range assayed, 25-200 microg/L, with determination coefficients of >0.996. The proposed method was applied to the analysis of pesticides in honey samples, and low levels of a few pesticides (dichlofluanid, ethalfluralin, and triallate) were detected in some samples.

Food Contamination↗
PubMedDate not supplied

Pesticide-handling practices in agriculture in Tanzania: observational data from 27 coffee and cotton farms.

The practices of pesticide handling in agriculture were surveyed in 1991-1993 in Tanzania, to identify hazardous practices and farms where they occurred. The study involved 23 coffee farms with 246 persons exposed to hazardous practices, and four cotton farms with 45 exposed. An observation form addressed locations of important places with respect to pesticide spraying, storage, disposal, and equipment; personal protection; and hygiene. More pesticide formulations were used for coffee compared with cotton and by individual rather than cooperative farms. Coffee farms more often had unlabeled pesticide containers and missing mixing instructions, while cotton pesticides were stored in bedrooms, near food, and near open fires, and pesticide leftovers were often present. Hazardous practices were more pronounced at individual than cooperative farms, with significant differences in pesticide storage areas, as well as unlabeled and non-original containers. The study demonstrated the need to train farmers in pesticide safety, strengthen advisory and regulatory services, and extend protection to farm workers' families.

Agriculture↗
PubMedDate not supplied

Predicting and measuring environmental concentration of pesticides in air after soil application.

Pesticides can volatilize into the atmosphere, which affects the air quality. The ability to predict pesticide volatilization is an essential tool for human risk and environmental assessment. Even though there are several mathematical models to assess and predict the fate of pesticides in different compartments of the environment, there is no reliable model to predict volatilization. The objectives of this study were to evaluate pesticide volatilization under agricultural conditions using malathion [ O,O-dimethyl-S-(1,2-dicarbethoxyethyl)-dithiophosphate], ethoprophos (O-ethyl S,S-dipropylphosphorodithioate), and procymidone [N-(3,5-dichlorophenyl)-1,2-dimethylcyclopropane-1,2-dicarboximide] as test compounds and to evaluate the ability of the Pesticide Leaching Model (PELMO) to calculate the predicted environmental concentrations of pesticides in air under field conditions. The volatilization rate of procymidone, malathion, and ethoprophos was determined in a field study during two different periods (December 1998 and September 1999) using the Theoretical Profile Shape (TPS) method. The experiments were performed on bare silty soil in the Bologna province, Italy. Residues in the air were continuously monitored for 2 to 3 wk after the pesticide applications. The amount of pesticide volatilized was 16, 5, and 11% in December 1998 and 41, 23, and 19% in September 1999 for procymidone, malathion, and ethoprophos, respectively. In both these experiments, the PELMO simulations of the concentration of ethoprophos and procymidone were in good agreement with the measured data (factor +/- 1.1 on average). The volatilization of malathion was underestimated by a factor of 30 on average. These results suggest that volatilization described by PELMO may be reliable for volatile substances, but PELMO may underpredict volatilization for less-volatile substances.

Agriculture↗
PubMed1982

Toxicological significance of pesticide conjugates.

Products formed by the reaction of pesticides and their metabolites with endogenous chemicals (glucose, glucuronic acid, sulfate, glutathione, amino acid, etc.) are referred to as pesticide conjugates. Evidence to date suggests that this is a detoxification process since the resulting products are polar and usually rapidly eliminated from the body. However, very little is known about their acute toxicity, and almost nothing concerning the effects of chronic dietary exposure of animals to these materials. Though conjugates may be formed in vivo by animals administered the parent pesticide, this hardly can be considered an adequate means of assessing their toxic properties. Pesticide metabolites formed by primary metabolic reactions are often evaluated individually in both acute and subchronic toxicity tests, but similar experiments are not conducted with conjugates. To assume that pesticide conjugates are toxicologically insignificant is unsound scientifically, although the rationale for such an assumption is not completely without merit. Many polar compounds are inactive but many, including some conjugates, are biologically active and indeed may be very toxic. While elaborate toxicological investigations of all pesticide conjugates do not appear warranted, there is a clear need to strengthen the data base relative to their potential toxicological significance. Extensive investigations of selected model compounds, representing different pesticide groups and conjugate types, are in order if the issue is to be placed in proper perspective relative to the total safety evaluation of pesticidal chemicals.

Animals↗
PubMedDate not supplied

Determination of residues of 446 pesticides in fruits and vegetables by three-cartridge solid-phase extraction-gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

A method was developed for determination of residues of 446 pesticides in fruits and vegetables through the use of cleanup by a 3-cartridge solid-phase extraction-gas chromatography/ mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Fruit and vegetable samples (20 g) were extracted with 40 mL acetonitrile, salted out, and centrifuged. Half of the supernatant was passed into an Envi-18 cartridge, eluted with acetonitrile, and cleaned up with Envi-Carb and aminopropyl Sep-Pak cartridges in series after concentration of the eluates. Pesticides were eluted with acetonitrile-toluene (3 + 1, v/v), and eluates were concentrated to 0.5 mL and then added into internal standards after solvent exchange with 2 mL hexane and used for determination of 383 pesticides by GC/MS. The other half of the supernatant was concentrated to 1 mL and cleaned up with Envi-Carb and aminopropyl Sep-Pak cartridges in series. Pesticides were eluted with acetonitrile-toluene (3 + 1, v/v), and the eluates were concentrated to 0.5 mL, dried with nitrogen gas, diluted to 1.0 mL with acetonitrile-water (3 + 2, v/v), and used for determination of 63 pesticides by LC/MS/MS. The limit of detection for the method was 0.2-600 ng/g depending on the individual pesticide. In the method, fortification recovery tests at high, medium, and low levels were conducted on 6 varieties of fruits and vegetables, i.e., apples, oranges, grapes, cabbage, tomatoes, and celery, with average recoveries falling within the range of 55.0-133.8% for 446 pesticides, among which average recoveries between 60.0-120.0% accounted for 99% of the results. The relative standard deviation was between 2.1-39.1%, of which a relative standard deviation of 2.1-25.0% made up 96% of the results. Experiments proved that the method was applicable for determination of residues of 446 pesticides in fruit and vegetables.

Acetonitriles↗
PubMed2005

Pesticides and risk of Parkinson disease: a population-based case-control study.

BACKGROUND: Pesticide exposures are suspected risk factors for Parkinson disease (PD), but epidemiological observations have been inconsistent. OBJECTIVE: To investigate associations between pesticide exposures and idiopathic PD. DESIGN: Population-based case-control study. SETTING: Group Health Cooperative, a health care system in western Washington State, and the University of Washington. PARTICIPANTS: Two hundred fifty incident PD case patients and 388 healthy control subjects (age- and sex-matched). We assessed self-reported pesticide exposures using a structured interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined using logistic regression models, controlling for age, sex, and smoking. RESULTS: Odds ratios for occupational exposures were not significant but suggested a gradient that paralleled occupational exposures (pesticide worker: OR, 2.07; 95% CI, 0.67-6.38; crop farmer: OR, 1.65; 95% CI, 0.84-3.27; animal and crop farmer: OR, 1.10; 95% CI, 0.60-2.00; and dairy farmer: OR, 0.88; 95% CI, 0.46-1.70). Odds ratios for organophosphates paralleled the World Health Organization hazard classifications, with parathion much higher than diazinon or malathion. We also found elevated ORs from herbicides (OR, 1.41; 95% CI, 0.51-3.88) and paraquat (OR, 1.67; 95% CI, 0.22-12.76). We found no evidence of risk from home-based pesticide exposures. We found significantly increased ORs from lifelong well water consumption (OR, 1.81; 95% CI, 1.02-3.21). CONCLUSIONS: The findings for occupational pesticide exposures are consistent with a growing body of information linking pesticide exposures with PD. However, the lack of significant associations, absence of associations with home-based exposures, and weak associations with rural exposures suggest that pesticides did not play a substantial etiologic role in this population.

Adult↗
PubMed1996

Estimating underreported pesticide poisonings in Nicaragua.

We undertook to estimate the degree of underreporting to a regional pesticide poisoning registry, and to estimate the true incidence of poisoning in an agricultural region of Nicaragua. We surveyed 633 workers at 25 of 33 agricultural cooperatives and any nearby private forms in a area geographically convenient to the regional health headquarters with a short structured interview about pesticide poisonings. Eighty-three percent of workers described current use of pesticides. Twenty-five percent described a pesticide poisoning in the preceding 12 months, and almost one-half (48%) described having been made ill by pesticides at some point in time. Sixty-nine (11%) described a poisoning in the preceding month, 23 of whom had received medical attention. The names of the medically treated were sought in the Regional Pesticide Poisoning Registry for the survey year of 1988. Only 8 of the 23 subjects were found reported to the registry when a total of 1,143 human pesticide poisonings were reported in the entire region. Using 65% as an estimate of underreporting to the registry, we calculate that 3,300 (95% CI 2100-7500) poisonings had received treatment in the region in 1988, of whom more than 2,100 remained unreported. Based on the ratio of total poisonings (treated and untreated) to registry-reported poisonings among our survey respondents, we estimate that 6,700 (95% CI 4100-18000) systemic poisonings, occurred in 1988 in the region. Underreporting of pesticide poisonings disguises the enormity of the problem in developing countries. Even in a region with a strong emphasis on illness reporting for targeted conditions, underreporting is substantial. This method for estimating underreporting is easily applied and provides a rough estimate of registry underreporting and actual incidence for conditions identifiable by a community-applied questionnaire.

Adolescent↗
PubMed1998

Exposure opportunities of families of farmer pesticide applicators.

BACKGROUND: Families of farmer pesticide applicators have unusual opportunities for exposure, directly or indirectly, to pesticides. These exposures are not well characterized. METHODS: Subjects were 26,793 licensed private pesticide applicators enrolled in the Agricultural Health Study, a cohort study being conducted in Iowa and North Carolina. Questionnaires were completed by the applicators and their spouses. RESULTS: Many indirect exposure opportunities exist; for example, 21% of homes are within 50 yards of pesticide mixing areas, 27% of applicators store pesticides in their homes, and 94% of clothing worn for pesticide work is washed in the same machine as other laundry. Direct exposure opportunities also occur; for example, 51% of wives of applicators worked in the fields in the last growing season, 40% of wives have ever mixed or applied pesticides, and over half of children aged 11 or more do farm chores. DISCUSSION/CONCLUSIONS: The extent of the opportunities for exposure of family members of farmer pesticide applicators makes studies of their health important.

Adult↗
PubMed2002

Monitoring of pesticide residues on cucumber, tomatoes and strawberries in Gaza Governorates, Palestine.

Three techniques of gas chromatography (GC) either with flame photometric-detector (FPD), electron capture detector (ECD), or with mass-spectrometry (MS) were applied for identification and quantification of pesticide residues on 45 samples of cucumber, tomatoes, and strawberries in fifteen locations in Gaza Governorates. GC-FPD analysis showed the presence of four different organo-phosphorus (OP) pesticides, their levels were very low and below maximum residue limits (MRL's). GC-ECD detected ten different pesticides at levels below the MRL's. Using the GC-MS technique, alpha and beta-endosulfan, chlorpyrifos, carbofuran, chlorfluazuron, triadimenol I and II, penconazole, coptafolmetabolite, pyrimethanil and iprodione were detected and confirmed on some samples of cucumber, tomatoes and strawberries. All GC-MS pesticide residues detected on tomato were below the MRL's except chlorfluazuron while on strawberry were below the MRL's except penconazole, chlorfluazuron and pyrimethanil, but on cucumber were slightly higher than the MRL's except alpha and beta-endosulfan. Also, statistical analysis of pesticide residues in all samples showed that most of the detected residues mean were significantly lower than the MRL's (p < 0.05). Generally, tomatoes showed the least number and level of pesticide residues by all the GC-techniques. On the other hand, strawberries showed greater number and levels of pesticide residues, particularly by the GC-MS technique. These results indicate that the protective period to elapse before harvesting should be increased especially on strawberry. The results also can help in risk assessment of consumers exposure to the expected pesticide residues.

Chromatography, Gas↗
PubMedDate not supplied

Bioluminescence determination of enzyme activity of firefly luciferase in the presence of pesticides.

Firefly luciferase (EC 1.13.12.5) (FL) is the key enzyme in the firefly bioluminescence method (FB), which is widely used to determine the viability of living cells. The FB method can also be applied to monitoring the influence of different pollutants, such as pesticides. Firefly luciferase is a hydrophobic enzyme and its activity depends on the type of solvent, pH and substances present in the reaction mixture. The influence of three aromatic pesticides, including fenoxaprop-p-ethyl (I), diclofop-methyl (II) and metsulfuron methyl (III), on the enzyme activity was indirectly evaluated through the measurement of emitted light in the bioluminescence reaction, expressed in relative luminescence units (RLU). The reaction mixture used in the bioluminescence measurements consisted of: Tris buffer (pH 7.75), adenosine triphosphate (ATP) and ATP monitoring reagent, where FL is present. Ethanol-water solutions of each pesticide were then added at concentrations of 2.4 x 10(-4)-2.4 x 10(-8) mol/L. The FL activity inhibition factors (FL In%) were determined. The FL activity was maximally inhibited in the presence of all pesticides under study at a concentration of 2.4 x 10(-4) mol/L and was lowered by about 15-26% for pesticide I at concentrations of 2.4 x 10(-5)-2.4 x 10(-8) mol/L, whereas pesticides II and III, applied in the same concentration range, showed smaller FL inhibition values (5.3-20%). The pesticide degradation products (obtained after a 1 month period), measured in the same experimental conditions, in most cases exhibited a much less inhibitory effect on the enzyme activity than the corresponding initial pesticide.

Environmental Monitoring↗
PubMed2002

Occupational exposure to pesticides and cytogenetic damage: results of a Hungarian population study using the micronucleus assay in lymphocytes and buccal cells.

The frequency of micronuclei (MN) in peripheral blood lymphocytes and in buccal epithelial cells was used as a biomarker of genotoxic effects resulting from occupational exposure to pesticides. In addition, the cytokinesis-block proliferation index (CBPI) was calculated to detect possible variations in the proliferative kinetics of lymphocytes due to pesticide exposure. This study was performed on 84 pesticide-exposed workers and 65 unexposed controls from Hungary. The pesticide-exposed workers, classified as moderately and highly exposed, were also evaluated separately. Statistical evaluation of the cytogenetic biomarkers indicated that there were no significant differences between pesticide-exposed workers and controls, nor between moderately and highly exposed workers. Nevertheless, the statistical analysis revealed that additional factors such as age, sex, ingestion of raw vegetables, and working as a pesticide applicator affected lymphocyte MN frequency. In addition, age, sex, and smoking affected the frequency of MN in buccal cells. Results from the CBPI analysis showed that the proliferation index decreased with pesticide exposure and that this parameter was also affected by smoking and by the gender of individuals. The results of this study indicate no significant increase in MN in this group of Hungarian workers; however, the reduced CBPI in the highly exposed population suggests a possible genotoxic effect of pesticide exposure.

Adult↗
PubMed1999

Characteristics of persons who self-reported a high pesticide exposure event in the Agricultural Health Study.

Characteristics of persons who report high pesticide exposure events (HPEE) were studied in a large cohort of licensed pesticide applicators from Iowa and North Carolina who enrolled in the Agricultural Health Study between December 1993 and December 1995. Fourteen percent reported having "an incident or experience while using any pesticide which caused an unusually high personal exposure. " After taking into account total number of applications made and education, females (OR=0.76), applicators from NC (OR=0.65), and privately licensed applicators (OR=0.65) were less likely to have reported an HPEE. Work practices more common among both private and commercial applicators with an HPEE included delay in changing clothing or washing after pesticide application, mixing pesticide application clothing with the family wash, washing up inside the house after application, applying pesticides within 50 yards of their well, and storing pesticides in the home. Job characteristics more common among those with an HPEE included self-repair of application equipment and first pesticide use more than 10 years in the past. These job characteristics explained much of the difference in reported HPEE between males and females, but not between IA and NC subjects or between commercial or private applicators.

Adult↗
PubMed2000

Pesticide exposure of children in an agricultural community: evidence of household proximity to farmland and take home exposure pathways.

Children's exposure to organophosphorus (OP) pesticides in an agricultural community in central Washington State was determined. Spot urine and hand wipe samples were collected from 109 children 9 months to 6 years of age, as were house dust samples, and wipe samples from various surfaces. Children were categorized based on parental occupation (agricultural vs nonagricultural) and on household proximity to pesticide-treated orchards. Median house dust concentrations of dimethyl OP pesticides in homes of agricultural families were seven times higher than those of reference families (1. 92 vs 0.27 microg/g; P<0.001). Median pesticide metabolite concentrations in agricultural children were five times higher than those in reference children (0.05 vs 0.01 microg/ml; P=0.09). Median pesticide concentrations in housedust (P=0.01) and metabolite concentrations in urine (P=0.01) from agricultural families were significantly higher in the children living near treated orchards (within 200 ft or 60 m) than those living more distant. Ten of 61 agricultural children had detectable OP pesticide levles on their hands, whereas none of the reference children had detectable levels. These findings indicate that children living with parents who work with agricultural pesticides, or who live in proximity to pesticide-treated farmland, have higher exposures than do other children living in the same community

Agriculture↗
PubMed1996

Interaction of structurally diverse pesticides with the human MDR1 gene product P-glycoprotein.

P-glycoprotein (P-gp) is a 170-kDa membrane-bound glycoprotein shown to efflux a wide variety of chemicals, such as chemotherapeutic agents and carcinogens. Experiments were conducted using B16/F10 murine melanoma cells transfected with the human MDR1 gene (B16/hMDR1 cells), which codes for P-gp, to determine whether this transporter may contribute to the cellular efflux of some pesticides. Thirty-eight pesticides representing several classes of compounds were evaluated for their potential to bind to P-gp, as measured by the inhibition of efflux of the P-gp substrate doxorubicin. Carbamate and pyrethroid insecticides exhibited little interaction with P-gp, while many of the organophosphorus and organochlorine pesticides significantly inhibited the efflux of doxorubicin. Pesticides that significantly inhibited the efflux of doxorubicin were then assessed for P-gp-mediated efflux. One pesticide, endosulfan, exhibited slight though significant transport mediated by P-gp. Competition experiments performed with the P-glycoprotein ligand [3H]azidopine demonstrated that the P-gp inhibitory pesticides bound to P-gp. Both lipophilicity and molecular mass were major physical/chemical determinants in dictating pesticide binding to P-gp, with optimum binding occurring with compounds having a log Kow value of 3.6-4.5 and a molecular weight of 391-490 Da. The transport substrate endosulfan possessed optimal binding characteristics. These results demonstrated that many pesticides are capable of binding to P-gp; however, binding does not infer transport.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

National standards and guidelines for pesticides in water, sediment, and aquatic organisms: application to water-quality assessments.

National standards and guidelines for pesticides can be useful tools in water-quality assessment for evaluating potential human health or ecological effects of measured pesticide residues in water, bed sediment, or aquatic organisms. However, valid use of a given standard or guideline requires an understanding of its technical basis and underlying assumptions. Each type of standard or guideline is specific for one sampling medium (water, bed sediment, and fish and shellfish tissue) and is aimed at protection of one or more beneficial uses of the hydrologic system (drinking water, fish and shellfish consumption, aquatic organisms, and wildlife). These characteristics can be used to identify which standards and guidelines are appropriate for comparison with measured pesticide concentrations in environmental samples from a given hydrologic system. A review of standards and guidelines can be restricted to the applicable sampling medium. Then, the beneficial uses of the hydrologic system need to be identified and the measured pesticide concentrations compared with standards and guidelines for all beneficial uses that apply to that system. Several key factors that must be considered when applying this general process to water-quality assessment are summarized below. Two precautions need to be considered regarding sampling media: 1. Standards and guidelines for water distinguish between finished drinking water (potable water, often treated) and ambient surface water. If standards and guidelines for drinking water (EPA primary drinking-water regulations and drinking-water health advisories) are applied to measured pesticide concentrations in ambient water samples, the effects of water treatment (such as filtration) need to be considered. 2. Standards and guidelines for fish and shellfish tissue distinguish between edible fish and shellfish tissue and whole fish tissue. Comparison of pesticide concentrations in whole fish tissue with standards or guidelines for edible fish and shellfish tissue is appropriate only as a screening procedure to determine whether additional sampling and analysis for contaminants in edible fish fillets are warranted. For some sampling media (water, fish and shellfish tissues), both standards and guidelines may exist for a given pesticide. Standards and guidelines may differ in their technical bases and in the implications or consequences of finding measured concentrations in exceedance of the standard or guideline value. Therefore, comparison of measured pesticide concentrations with both standards and guidelines is useful because each provides different information about the hydrologic system.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗