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PubMed2004

Using a linked soil model emulator and unsaturated zone leaching model to account for preferential flow when assessing the spatially distributed risk of pesticide leaching to groundwater in England and Wales.

Although macropore flow is recognized as an important process for the transport of pesticides through a wide range of soils, none of the existing spatially distributed methods for assessing the risk of pesticide leaching to groundwater account for this phenomenon. The present paper presents a spatially distributed modelling system for predicting pesticide losses to groundwater through micro- and macropore flow paths. The system combines a meta version of the mechanistic, dual porosity, preferential flow pesticide leaching model MACRO (the MACRO emulator), which describes pesticide transport and attenuation in the soil zone, to an attenuation factor leaching model for the unsaturated zone. The development of the emulator was based on the results of over 4000 MACRO model simulations. Model runs describe pesticide leaching for the range of soil types, climate regimes, pesticide properties and application patterns in England and Wales. Linking the MACRO emulator to existing spatial databases of soil, climate and compound-specific loads allowed the prediction of the concentration of pesticide leaching from the base of the soil profile (at 1 m depth) for a wide range of pesticides. Attenuation and retardation of the pesticide during transit through the unsaturated zone to the watertable was simulated using the substrate attenuation factor model AQUAT. The MACRO emulator simulated pesticide loss in 10 of 12 lysimeter soil-pesticide combinations, for which pesticide leaching was shown to occur and also successfully predicted no loss from 3 soil-pesticide combinations. Although the qualitative aspect of leaching was satisfactorily predicted, actual pesticide concentrations in leachate were relatively poorly predicted. At the national scale, the linked MACRO emulator/AQUAT system was found to predict the relative order of, and realistic regional patterns of, pesticide leaching for atrazine, isoproturon, chlorotoluron and lindane. The methodology provides a first-step assessment of the potential for pesticide leaching to groundwater in England and Wales. Further research is required to improve the modelling concept proposed. The system can be used to refine regional groundwater monitoring system designs and sampling strategies and improve the cost-effectiveness of the measures needed to achieve 'good status' of groundwater quality as required by the Water Framework Directive.

Journal Article↗
PubMed2004

Pesticide exposure--Indian scene.

Use of pesticides in India began in 1948 when DDT was imported for malaria control and BHC for locust control. India started pesticide production with manufacturing plant for DDT and benzene hexachloride (BHC) (HCH) in the year 1952. In 1958, India was producing over 5000 metric tonnes of pesticides. Currently, there are approximately 145 pesticides registered for use, and production has increased to approximately 85,000 metric tonnes. Rampant use of these chemicals has given rise to several short-term and long-term adverse effects of these chemicals. The first report of poisoning due to pesticides in India came from Kerala in 1958 where, over 100 people died after consuming wheat flour contaminated with parathion. Subsequently several cases of pesticide-poisoning including the Bhopal disaster have been reported. Despite the fact that the consumption of pesticides in India is still very low, about 0.5 kg/ha of pesticides against 6.60 and 12.0 kg/ha in Korea and Japan, respectively, there has been a widespread contamination of food commodities with pesticide residues, basically due to non-judicious use of pesticides. In India, 51% of food commodities are contaminated with pesticide residues and out of these, 20% have pesticides residues above the maximum residue level values on a worldwide basis. It has been observed that their long-term, low-dose exposure are increasingly linked to human health effects such as immune-suppression, hormone disruption, diminished intelligence, reproductive abnormalities, and cancer. In this light, problems of pesticide safety, regulation of pesticide use, use of biotechnology, and biopesticides, and use of pesticides obtained from natural plant sources such as neem extracts are some of the future strategies for minimizing human exposure to pesticides.

Animals↗
PubMed2004

Applicability of headspace solid-phase microextraction to the determination of multi-class pesticides in waters.

The applicability of headspace solid-phase microextraction (HS-SPME) to pesticide determination in water samples was demonstrated by evaluating the effects of temperature on the extraction of the pesticides. The evaluations were performed using an automated system with a heating module. The 174 pesticides that are detectable with gas chromatograph were selected objectively and impartially based on their physical properties: vapor pressure and partition coefficient between octanol and water. Of the 174 pesticides, 158 (90% of tested) were extracted with a polyacrylate-coated fiber between 30 and 100 degrees C and were determined with gas chromatograph-mass spectrometry. The extraction-temperature profiles of the 158 extracted pesticides were obtained to evaluate the effects of temperature on the extraction of pesticides. The pesticides were classified into four groups according to the shape of their extraction-temperature profiles. The line of demarcation between extractable pesticides and non-extractable pesticides could be drawn in the physical property diagram (a double logarithmic plot of their vapor pressure and partition coefficient between octanol and water). The plot also revealed relationships between classified extraction features and their physical properties. The new method for multi residue screening in which the analytes were categorized into sub-groups based on extraction temperature was developed. In order to evaluate the quantitivity of the developed method, the 45 pesticides were chosen among the pesticides that are typically monitored in waters. Linear response data for 40 of the 45 was obtained in the concentration range below 5 microg/l with correlation coefficients ranging between 0.979 and 0.999. The other five pesticides had poor responses. Relative standard deviations at the concentration of the lowest standard solution for each calibration curve of the pesticides ranged from 3.6 to 18%. The value of 0.01 microg/l in the limits of detection for 17 pesticides was achieved only under the approximate conditions for screening, not under the individually optimized conditions for each pesticide. Recoveries of tested pesticides in actual matrices were essentially in agreement with those obtained by solid-phase extraction.

Chromatography, Gas↗
PubMedDate not supplied

Knowledge, attitudes and practices (KAP) among agricultural extension workers concerning the reduction of the adverse impact of pesticides in agricultural areas in Tanzania.

BACKGROUND: Extension workers are educated locally to enable them to train farmers in using improved local farming methods and imported technology, such as pesticides, to increase crop production. However, the extension workers are not adequately trained in health aspects of pesticides and hence are unable to provide adequate services to farmers with regard to safe use of pesticides. OBJECTIVE: The present study assessed the knowledge, attitudes and practices of agricultural extension workers with respect to health effects of pesticides in order to develop strategies for the control of pesticide exposure and prevention of pesticide poisoning in Tanzania. METHODS: A survey of Tanzanian agricultural extensionists was undertaken in 1991-1994 using a standardized questionnaire in face-to-face interviews. Extensionists who were district agricultural officers, assistant agricultural officers, agricultural assistants, and field assistants, working in the coffee and cotton growing areas (N = 61) within a radius of 15 km of farm, estate or village under farm worker study (reported elsewhere) were included in the survey. RESULTS: The majority of extensionists knew that pesticides could enter the human body but only a quarter perceived pesticides as a major problem in the community they served. The majority showed awareness of potential health hazards of the different pesticides used in their service areas, but they did not recognize what pesticides were responsible for poisoning. A high proportion was familiar with first aid procedures in case of pesticide poisoning; however, many procedures described were not appropriate for pesticide poisoning. CONCLUSIONS: The survey indicated that training of agricultural workers in health aspects of pesticide exposure is an important task for adequate provision of service to farmers with regard to safe use of pesticides in Tanzania. Nevertheless, the appropriate role of extensionists in reducing the health impact of pesticides would be to advocate pesticides of low toxicity or non-chemical pest control.

Adult↗
PubMed2006

Application of artificial neural networks to assess pesticide contamination in shallow groundwater.

In this study, a feed-forward back-propagation neural network (BPNN) was developed and applied to predict pesticide concentrations in groundwater monitoring wells. Pesticide concentration data are challenging to analyze because they tend to be highly censored. Input data to the neural network included the categorical indices of depth to aquifer material, pesticide leaching class, aquifer sensitivity to pesticide contamination, time (month) of sample collection, well depth, depth to water from land surface, and additional travel distance in the saturated zone (i.e., distance from land surface to midpoint of well screen). The output of the neural network was the total pesticide concentration detected in the well. The model prediction results produced good agreements with observed data in terms of correlation coefficient (R=0.87) and pesticide detection efficiency (E=89%), as well as good match between the observed and predicted "class" groups. The relative importance of input parameters to pesticide occurrence in groundwater was examined in terms of R, E, mean error (ME), root mean square error (RMSE), and pesticide occurrence "class" groups by eliminating some key input parameters to the model. Well depth and time of sample collection were the most sensitive input parameters for predicting the pesticide contamination potential of a well. This infers that wells tapping shallow aquifers are more vulnerable to pesticide contamination than those wells tapping deeper aquifers. Pesticide occurrences during post-application months (June through October) were found to be 2.5 to 3 times higher than pesticide occurrences during other months (November through April). The BPNN was used to rank the input parameters with highest potential to contaminate groundwater, including two original and five ancillary parameters. The two original parameters are depth to aquifer material and pesticide leaching class. When these two parameters were the only input parameters for the BPNN, they were not able to predict contamination potential. However, when they were used with other parameters, the predictive performance efficiency of the BPNN in terms of R, E, ME, RMSE, and pesticide occurrence "class" groups increased. Ancillary data include data collected during the study such as well depth and time of sample collection. The BPNN indicated that the ancillary data had more predictive power than the original data. The BPNN results will help researchers identify parameters to improve maps of aquifer sensitivity to pesticide contamination.

Environmental Monitoring↗
PubMedDate not supplied

Loss of pesticides from agricultural fields in SE Norway--runoff through surface and drainage water.

Loss of two pesticides with different mobility characteristics, bentazone (Koc approximately 34) and propiconazole (Koc approximately 1800), were studied at three agricultural fields (Askim, Bjørnebekk and Syverud) in SE Norway. A conservative tracer (Br) was used to follow the flow of water. The loss of pesticides varied among the fields, depending on hydrological characteristics and soil properties. The loss of pesticides was higher from two artificially levelled silty clay loam soils with poor aggregate stability (Askim and Bjørnebekk) compared to a loam/silt loam soil with increased content of organic carbon and better aggregate stability (Syverud). The total accumulated loss was <0.5% from all fields. The highest pesticide concentrations were measured at the first runoff episode after application for both the mobile (bentazone) and less mobile pesticide (propiconazole) in the surface runoff. In the drainage water, the peak for the less mobile pesticide coincided with the Br tracer, while the peak for mobile pesticide appeared earlier than the Br tracer. Rapid movement of water, particles and pesticides through soils indicate flow through macropores. Larger proportions (in percent of total applied) of both the mobile and the strongly sorbed pesticides were lost through the drainage as compared to the loss through surface runoff at Askim. Here, it is suggested that macropore flow contribute to the increased loss of pesticides through the drainage. At Syverud, high infiltration capacity reduces the amount of water available for surface runoff, and somewhat higher loss of the mobile pesticide was registered in the drainage compared to the surface runoff. For the strongly sorbed pesticide, however, propiconazole was neither detected in surface nor in drainage water at Syverud. Generally, there was a higher percentage loss of the mobile compared to the strongly sorbed pesticide in both surface and drainage water, which is in agreement with the pesticides mobility characteristics in soil. An exception was, however, the erodible soil Bjørnebekk, where a higher fraction of propiconazole was lost in the surface runoff compared to bentazone. Large amounts of sediment transport from the Bjørnebekk field probably contributed to enhanced transport of the strongly sorbed pesticide.

Adsorption↗
PubMed2006

Use of point-of-sale data to track usage patterns of residential pesticides: methodology development.

BACKGROUND: Residential-use pesticides have been shown to be a major source of pesticide exposure to people in the United States. However, little is understood about the exposures to household pesticides and the resultant health effects. One reason that little is known about home-use pesticide exposure is the lack of comprehensive data on exposures to pesticides in the home. One method to help ascertain the amount of pesticides present in the home is use of point-of-sale data collected from marketing companies that track product sales to obtain the volume of pesticides sold for home-use. This provides a measure of volume of home-use pesticide. METHODS: We have constructed a searchable database containing sales data for home-use permethrin-containing pesticides sold by retail stores in the United States from January 1997 through December 2002 in an attempt to develop a tracking method for pesticide. This pilot project was conducted to determine if point-of-sale data would be effective in helping track the purchase of home-use permethrin containing pesticides and if it would stand as a good model for tracking sales of other home-use pesticides. RESULTS: There are several limitations associated with this tracking method, including the availability of sales data, market coverage, and geographic resolution. As a result, a fraction of sales data potentially available for reporting is represented in this database. However, the database is sensitive to the number and type of merchants reporting permethrin sales. Further, analysis of the sale of individual products included in the database indicates that year to year variability has a greater impact on reported permethrin sales than the amount sold by each type of merchant. CONCLUSION: We conclude that, while nothing could completely replace a detailed exposure assessment to estimate exposures to home-use pesticides, a point-of-sale database is a useful tool in tracking the purchase of these types of pesticides to 1) detect anomalous trends in regional and seasonal pesticide sales warranting further investigation into the potential causes of the trends; 2) determine the most commonly purchased application types; and 3) compare relative trends in sales between indoor and outdoor use products as well as compare trends in sales between different active ingredients.

Commerce↗
PubMed1996

Swedish pesticide risk reduction 1981-1995: food residues, health hazard, and reported poisonings.

The Swedish Government has initiated three pesticide risk-reduction programs since the mid-1980s. Risk-reduction achievements have been measured mainly in terms of reduction in quantities sold. In this review, risk-reduction achievements have been described also in terms of pesticide residues in foods, both imported and grown domestically, acute health hazard to the users, and reported poisonings. The time periods selected for comparisons are 1981-1985 (which is the Government's baseline period), 1990-1994 for food residues and poisonings, and 1991-1995 for acute health hazard and quantities sold. The quantity of pesticides as active ingredient (ai) sold for use in agriculture, horticulture, and forestry decreased from a total of 22,800 tons during 1981-1985 to 8450 tons in 1991-1995, a 63% reduction. Published data on pesticide residues in domestically grown fruits and vegetables show that the proportion of cases of reported residues higher than 20% of the maximum residue limit has decreased only slightly, from 6.9% to 6.2%. Residues in imported food crops of the same type increased from 31% to 37%. Overall, the achieved 63% reduction of quantities used may have resulted in only a 10% reduction in number of cases of reported residues. A forthcoming report on pesticide intake via food from the National Food Administration may shed light on any trends in actual residue levels. The degree of goal fulfillment for the pesticide residue monitoring program and for pesticide residue levels in food is difficult to judge because of imprecise goal formulations. An estimate of the potential acute health hazard to the pesticide users, based on quantities and acute toxicity of individual pesticides, indicates that the acute health hazard in terms of "acute toxicity equivalents" decreased by 71%. The number of poisonings caused by acute exposure at the workplace has decreased between 1984 and 1994, whereas the number of mostly harmless incidents at home has increased. The decline in workplace-related accidents and the favorable pattern and low frequency of pesticide poisonings in Sweden compared to many other countries, especially developing countries, is the result of several factors, such as the mandatory training of workers using pesticides professionally, severe restrictions in availability of pesticides for use in households, and withdrawal from the market of the most toxic pesticides. To improve the worrisome global situation, it would seem appropriate that the United Nations Food and Agriculture Organization pay greater attention to the need for promotion of restrictions on availability of highly toxic and other pesticides, as recommended by FAO and WHO in 1975 (WHO/FAO 1975).

Environmental Exposure↗
PubMed1997

Pesticide prioritization for a brain cancer case-control study.

The incidence of brain cancer is rising in the United States while the causes remain largely unknown. Epidemiologic studies indicate that individuals working in agriculture have an increased risk of brain cancer. The National Institute for Occupational Safety and Health is conducting a case-control study of incident brain cancer cases in Iowa, Michigan, Minnesota, and Wisconsin to evaluate the risk associated with several environmental exposures, in particular agricultural pesticides. Hundreds of different pesticides are used in agriculture and it is not feasible to evaluate the association between brain cancer and exposure to each of these chemicals; therefore, a strategy was developed to identify which pesticides would be targeted in the study. First lists of pesticides were created, documenting usage in each of the four states and the United States as a whole, by using data from reports prepared by the U.S. Department of Agriculture and Departments of Agriculture and land grant colleges within the four states. Then the following factors were considered in prioritizing pesticides for evaluation in the study: total volume of use prior to 1985, ranking of use in the four states and the United States as a whole by pesticide category, and toxicological evidence of carcinogenic, teratogenic, or mutagenic effects. Pesticide usage prior to 1985 was determined to allow for a minimum 10-year latency for the incident brain cancer cases diagnosed in 1995 or later. The selected pesticides include 56 herbicides, 49 insecticides, 12 fungicides, and 17 fumigants, accounting for over 99% of the total pounds of herbicides and insecticides and over 98% of the total pounds of fungicides and fumigants applied pre-1985. Prompt lists of the pesticides are sent to study participants a few days before the study questionnaire is administered to allow them time to recall past use of pesticides; the lists include the common chemical names, trade names, the crops that the pesticides are most commonly used on, and the years that the pesticides have been marketed. The methods used to select this subset of 134 pesticides document historical usage and may be useful in prioritizing pesticides for other research studies.

Brain Neoplasms↗
PubMed2006

Spatial relationships between water quality and pesticide application rates in agricultural watersheds.

Pesticide applications to agricultural lands in California, USA, are reported to a central data base, while data on water and sediment quality are collected by a number of monitoring programs. Data from both sources are geo-referenced, allowing spatial analysis of relationships between pesticide application rates and the chemical and biological condition of water bodies. This study collected data from 12 watersheds, selected to represent a range of pesticide usage. Water quality parameters were measured during six surveys of stream sites receiving runoff from the selected watershed areas. This study had three objectives: to evaluate the usefulness of pesticide application data in selecting regional monitoring sites, to provide information for generating and testing hypotheses about pesticide fate and effects, and to determine whether in-stream nitrate concentration was a useful surrogate indicator for regional monitoring of toxic substances. Significant correlations were observed between pesticide application rates and in-stream pesticide concentrations (p < 0.05) and toxicity (p < 0.10). In-stream nitrate concentrations were not significantly correlated with either the amount of pesticides applied, in-stream pesticide concentrations, or in-stream toxicity (all p > 0.30). Neither total watershed area nor the area in which pesticide usage was reported correlated significantly with the amount of pesticides applied, in-stream pesticide concentrations, or in-stream toxicity (all p > 0.14). In-stream pesticide concentrations and effects were more closely related to the intensity of pesticide use than to the area under cultivation.

Agriculture↗
PubMed2006

Leaching and degradation of 21 pesticides in a full-scale model biobed.

Filling and cleaning of pesticide sprayers presents a potential risk of pollution of soil and water. Three different solutions for handling sprayers have been suggested: Filling and cleaning in the field, filling and cleaning on hard surfaces with collection of the waste water, and filling and cleaning on a biobed, which is an excavation lined with clay and filled with a mixture of chopped straw, sphagnum and soil with turf on top, and with increased sorption capacity and microbial activity for degradation of the pesticides. In the present study the degradation and leaching of 21 pesticides (5 g of each) was followed in an established full-scale model biobed. Percolate was collected and analysed for pesticide residues, and the biobed material was sampled at three different depths and analysed by liquid chromatography double mass spectrometry (LC-MSMS). During the total study period of 563 days, no traces of 10 out of 21 applied pesticides were detected in the percolate (detection limits between 0.02 and 0.9 microg l(-1)) and three pesticides were only detected once and at concentrations below 2 microg l(-1). During the first 198 days before second application, 14% of the applied herbicide bentazone was detected in the leachate with maximum and mean concentrations of 445 and 172 microg l(-1), respectively. About 2% of the initial mecoprop and fluazifop dose was detected in the percolate, with mean concentrations of 23 microg l(-1), while MCPA and dimethoate had mean concentrations of 3.5 and 4.7 microg l(-1), respectively. Leachate concentrations for the remaining pesticides were generally below the detection limit (0.02-0.9 microg l(-1), below 1% of applied). Sorption studies of five pesticides showed that compounds with a low K(d) value appeared in the leachate. After 169 days, all pesticides in the biobed profile were degraded to a level below 50% of the calculated initial dose. Pesticides with K(oc) values above 100 were primarily found in the uppermost 10 cm and degraded slowest due to the low bioavailability. The 11 most degradable pesticides were all degraded such that less than 3% remained in the biobed after 169 days. Following second pesticide application of the biobed, leachate was sampled 215 and 365 days after the treatment. This showed the same pesticides to be leached out and at concentrations comparable to those of the first treatment. The same pesticides as after the first treatment were retained in the biobed.

Chromatography, High Pressure Liquid↗
PubMed2006

Maternal hair--an appropriate matrix for detecting maternal exposure to pesticides during pregnancy.

The detection of exposure of pregnant women to toxicants in the environment is important because these compounds can be harmful to the health of the woman and her fetus. The aim of this study was to analyze for pesticides/herbicides in paired maternal hair and blood samples to determine the most appropriate matrix for detecting maternal exposure to these compounds. A total of 449 pregnant women were prospectively recruited at midgestation from an agricultural site in the Philippines where a preliminary survey indicated significant use at home and on the farm of the following compounds: propoxur, cyfluthrin, chlorpyrifos, cypermethrin, pretilachlor, bioallethrin, malathion, diazinon, and transfluthrin. Paired maternal hair and blood samples were obtained from each subject upon recruitment into the study (midgestation) and at birth and were analyzed for the above compounds, as well as lindane and DDT [1,1,1-trichloro-2-2-bis(p-chlorophenyl) ethane], and some of their known metabolites by gas chromatography/mass spectrometry. The highest exposure rate was seen for propoxur and bioallethrin and maternal hair analysis provided the highest detection rate for these two compounds, compared to blood, at both time periods: (1) At midgestation, 10.5% positive for propoxur in hair compared to 0.7% in blood (P<0.001) and for bioallethrin, 11.9% positive in hair compared to 0% in blood (P < or = 0.001), and (2) at birth, 11.8% positive for propoxur in hair compared to 4% in blood (P < or = 0.001) and for bioallethrin, 7.8% in hair compared to 0% in blood (P < or = 0.001). A small number of maternal hair samples were also positive for malathion, chlorpyrifos, pretilachlor, and DDT. Only a few of the pesticide metabolites were detected, principally 3-phenoxybenzoic acid, malathion monocarboxylic acid, and DDE [1,1,dichloro-2-2-bis(p-chlorophenyl)ethylene], and they were mostly found in maternal blood. There was a significant association between the use of the home spray pesticide, Baygon, and propoxur in maternal hair at birth (P=0.001) and between the use of a slow-burning mosquito coil and the presence of bioallethrin in maternal hair at midgestation and at birth (P=0.001, P < or = 0.041, respectively). There is significant exposure of the pregnant woman to pesticides, particularly to pesticides that are used at home. Our study demonstrates the advantages of analyzing maternal hair as a readily available biologic matrix for studying maternal exposure to toxicants in the environment, compared to blood. For propoxur, there was a 3- to 15-fold higher detection rate of the pesticide in maternal hair as compared to blood. As for the other pesticides, bioallethrin, malathion, chlorpyrifos, and DDT were exclusively found in maternal hair compared to blood. On the other hand, pesticide metabolites were infrequently found in maternal hair or maternal blood. Pesticides in blood most likely represent acute exposure, whereas pesticides in hair represent past and/or concurrent exposure. The high sensitivity, wide window of exposure, availability, and ease of hair collection are distinct advantages in using hair to detect exposure to pesticides among pregnant women. However, pesticides in maternal hair may also be secondary to passive exposure and therefore not truly representative of the internal pesticide dose. Finally, the analysis of maternal hair for pesticides as an index of maternal exposure to pesticides in the environment allows the institution of measures to prevent further exposure during pregnancy.

Adult↗
PubMed2005

Pesticide exposure of non-occupationally exposed subjects compared to some occupational exposure: a French pilot study.

Data about non-dietary exposure to different chemical classes of pesticides are scarce, especially in France. Our objective was to assess residential pesticide exposure of non-occupationally exposed adults, and to compare it with occupational exposure of subjects working indoors. Twenty unexposed persons, five gardeners, seven florists and nine veterinary workers living in Paris area were recruited. Nineteen residences, two greenhouses, three florist shops and three veterinary departments were then sampled. Thirty-eight insecticides, herbicides and fungicides were measured in indoor air with an air sampler for 24 h, and on hands by wiping them with isopropanol-wetted swabs. After extraction, samples were analysed by gas and high-performance liquid chromatography. Seventeen different pesticides were detected at least once in indoor air and twenty-one on the hands. An average of 4.2+/-1.7 different pesticides was detected per indoor air sample. The organochlorines lindane, alpha-endosulfan and alpha-HCH were the most frequently detected compounds, in 97%, 69% and 38% of the samples, respectively. The organophosphates dichlorvos and fenthion, the carbamate propoxur and the herbicides atrazine and alachlor were detected in more than 20% of the air samples. Indoor air concentrations were often low, but could reach 200-300 ng/m(3) in residences for atrazine and propoxur. Propoxur levels significantly differed between the air of veterinary places and other places (Kruskal-Wallis test, p<0.05) and dieldrin levels between residences and workplaces (p<0.05). There was a greater number of pesticides on hands than in air, with an average of 6.3+/-3.3 different pesticides detected per sample, the most frequently detected being malathion, lindane and trifluralin, in more than 60% of the subjects. Maximal levels (up to 1000-3000 ng/hands) were observed either in the general population or in workers, depending on the pesticide. However, no significant difference was observed between workers and general population handwipe pesticide levels. As expected, gardeners were exposed to pesticides sprayed in greenhouses. Florists and veterinary workers, whose pesticide exposure had not been described until now, were also indirectly exposed to pesticides used for former pest control operations. Overall, general population was exposed to more various pesticides and at levels sometimes higher than in occupational places. The most frequent pesticides in residences were not the same as in US studies but levels were similar. These preliminary results need to be confirmed in a greater number of residences from different parts of the country, in order to better assess pesticide exposure of the general population and its influencing factors.

Acetamides↗
PubMed1998

Pesticides in stream water within an agricultural catchment in southern Sweden, 1990-1996.

Pesticide loss to stream water was studied in a small agricultural catchment in southern Sweden during the period 1990-1996. A total of 38 pesticides were detected in water samples, including 30 herbicides, four fungicides, three insecticides and one metabolite of one of the herbicides. Concentrations of pesticides in stream water were observed throughout the sampling periods. Peak concentrations occurred during the spraying seasons and following runoff events. Daily average concentrations sometimes varied by one order of magnitude from one day to another. Pesticides were also found in water samples as a result of incautious actions during handling and application procedures. Concentrations were lower at the outlet of the catchment area when the water had passed an open part of the stream, compared to concentrations detected in discharge from a culvert system upstream. This was largely a result of dilution from groundwater intrusion during low-flow periods. Sampling at different sites along the culvert demonstrated that the small village situated in the catchment did not contribute to pesticide findings in the culvert discharge. Wind drift had little influence on stream-water quality. Pesticide application for weed control in farmyards resulted in a substantial contribution to the pesticide load in stream water. Pesticide were persistent in the discharge throughout the winter and originated from both autumn and spring applications, as well as from farmyard application. Some autumn applied pesticides prevailed in stream flow during the following summer. Total amounts of pesticides lost in stream flow during May-September each year varied between 0.5 and 2.8 kg during the 7-year period, corresponding to approximately 0.1% of the applied amount. Losses of single pesticides were generally less than 0.3% of the applied amount during individual years. Pesticides from agricultural applications in the catchment constituted, on average, 82% of the total transported amount lost during May-September each year, of which 2% was from autumn application the previous year. There was an overall correlation between amounts used in the catchment and occurrence in the water samples. The total pesticide load in water decreased markedly during the course of the investigation, in accordance with decreased amounts applied during spring and early summer. The results indicate that concentrations of some pesticides entering head-water streams in agricultural areas are close to, and during certain time periods even above those levels demonstrated as having an impact on the aquatic flora and fauna.

Agriculture↗
PubMed2006

Pesticide mixtures, endocrine disruption, and amphibian declines: are we underestimating the impact?

Amphibian populations are declining globally at an alarming rate. Pesticides are among a number of proposed causes for these declines. Although a sizable database examining effects of pesticides on amphibians exists, the vast majority of these studies focus on toxicological effects (lethality, external malformations, etc.) at relatively high doses (parts per million). Very few studies focus on effects such as endocrine disruption at low concentrations. Further, most studies examine exposures to single chemicals only. The present study examined nine pesticides (four herbicides, two fungicides, and three insecticides) used on cornfields in the midwestern United States. Effects of each pesticide alone (0.1 ppb) or in combination were examined. In addition, we also examined atrazine and S-metolachlor combined (0.1 or 10 ppb each) and the commercial formulation Bicep II Magnum, which contains both of these herbicides. These two pesticides were examined in combination because they are persistent throughout the year in the wild. We examined larval growth and development, sex differentiation, and immune function in leopard frogs (Rana pipiens). In a follow-up study, we also examined the effects of the nine-compound mixture on plasma corticosterone levels in male African clawed frogs (Xenopus laevis). Although some of the pesticides individually inhibited larval growth and development, the pesticide mixtures had much greater effects. Larval growth and development were retarded, but most significantly, pesticide mixtures negated or reversed the typically positive correlation between time to metamorphosis and size at metamorphosis observed in controls: exposed larvae that took longer to metamorphose were smaller than their counterparts that metamorphosed earlier. The nine-pesticide mixture also induced damage to the thymus, resulting in immunosuppression and contraction of flavobacterial meningitis. The study in X. laevis revealed that these adverse effects may be due to an increase in plasma levels of the stress hormone corticosterone. Although it cannot be determined whether all the pesticides in the mixture contribute to these adverse effects or whether some pesticides are effectors, some are enhancers, and some are neutral, the present study revealed that estimating ecological risk and the impact of pesticides on amphibians using studies that examine only single pesticides at high concentrations may lead to gross underestimations of the role of pesticides in amphibian declines.

Amphibians↗
PubMed1991

Non-target and environmental hazards of pesticides.

When compared with pesticide pollution from other sources and pollution by other agents, the hazards of atmospheric pollution by pesticides appear relatively insignificant. The high persistency in the environment observed especially with the organochlorines suggests that there could be a gradual accumulation of residual pesticides in the atmosphere. Thus, in addition to the function of redistributing pesticides by air currents and aerial drifts, the atmosphere may become a major reservoir for drift prone finely divided particulate pesticides and highly volatile compounds. Indiscriminate aerial spraying should be avoided. A more selective approach should be adopted whereby forest areas are sprayed without contaminating streams, lakes and inland waters. Improvement in spraying devices are needed such that pesticides are more precisely delivered to target. Direct spraying of water bodies should be avoided as much as possible. Treatment of waste water for pesticide removal or neutralization prior to effluence from factories and disposal of effluence to legally designated sites in addition to chemical treatment of contaminated water are more ways of reducing water pollution. Pesticide residues in soil, in addition to eliminating or reducing parasitic microbes, are also toxic to the non-parasitic and ecologically useful soil microbial and vertebrate population. Pesticides may reduce certain microorganism populations while they stimulate the growth of others, especially the saphrophytic and spore forming types. Soil chemical properties may also be altered by accumulation of residual pesticides and their metabolites. These processes may disrupt the ecological balance in the soil microenvironment, first by simplifying the microbial population, and possibly by reducing soil fertility and its ability to support life. Non-target or residual pesticide toxicity would also disrupt the population of some of the valuable soil invertebrates like earthworms, predatory mites, centipedes and carabid beetles. Accumulation of pesticides in resistant or tolerant species may provoke episodes of toxicity to organisms higher in the food chain. The chlorinated hydrocarbons are likely to be most ecotoxic. Use of such pesticides ought to be restricted. Efforts to find alternatives to pesticides, especially research into biological control, should be intensified.

Air Pollution↗
PubMed2004

Growth and survival of five amphibian species exposed to combinations of pesticides.

The global decline of amphibians has sparked interest in the role that pesticides may play. Pesticides in nature typically exist in combinations, but given the vast number of chemicals used, most toxicological experiments necessarily have examined one pesticide at a time. I examined how four commercial formulations of pesticides (diazinon, carbaryl, malathion, and glyphosate) affected the survival and growth of five larval amphibian species (Rana pipiens, R. clamitans, R. catesbeiana, Bufo americanus, and Hyla versicolor) when alone (at 1 or 2 mg/L of active ingredient) and in pairwise combinations (1 mg/L of each pesticide). At 1 mg/L, the pesticides reduced survival in 5% of the 20 species-pesticide comparisons and reduced growth in 35% of the comparisons. At 2 mg/L, the pesticides had more widespread effects, reducing survival in 35% of the 20 species-pesticide comparisons and reducing growth in 70% of comparisons. Combined pesticides occasionally caused lower survival and growth than either pesticide alone, but the effects were never larger than the more deadly of the two pesticides alone at 2 mg/L. This suggests that the impact of combining these four pesticides is similar to that predicted by the total concentration of pesticides in the system.

Amphibians↗
PubMed2003

Atlas of pesticide concentrations in Dutch surface waters: a pilot study.

A pilot study was conducted to explore the potential for geographically mapping concentrations of individual pesticides in Dutch surface waters and compiling these maps into a National Pesticide Atlas. This atlas could be used for various purposes: 1) To see where specific pesticides are monitored, observed and find out whether these are problematical. 2) To explore the relationship between environmental pesticide levels and land use, using the results as feedback to improve national pesticide admission procedures (post-registration review) 3) To review the quality of the present Dutch pesticide monitoring system. For the study we used measured data for the years 1997 and 1998, preparing maps for six illustrative pesticides. The data are presented on a grid scale of 5x5 km2. Pesticide concentrations are compared with three standards: the EU drinking water standard, the maximum tolerable risk (MTR) level and the admission standard set by the Dutch Pesticide Admission Board (CTB). The results show that all these pesticides can be satisfactorily mapped at the national level and that for most of the compounds investigated a useful relationship can be established between environmental concentration and land use. The maps also serve to show up gaps in the present pesticide monitoring system. The study yielded several new insights, among them that standards were found to be exceeded in areas and at times of the year not anticipated on the basis of land use and pesticide use statistics. As a follow-up to this pilot study a new project has been started to develop an internet version of the pesticide atlas for all measured pesticides in The Netherlands.

Environmental Monitoring↗