Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PESTICIDES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed2006

Pesticide poisoning of farm workers-implications of blood test results from Vietnam.

Information on the health impacts of pesticides is quite limited in many developing countries, with many surveys relying solely on farmer self-assessments of their health status. To test the reliability of self-reported data, an acetyl cholinesterase enzyme (AChE) blood test was conducted for 190 rice farmers in the Mekong Delta, Vietnam. Results reveal a high prevalence of pesticide poisoning by organophosphate and carbamate exposure, where over 35% of test subjects experienced acute pesticide poisoning (a reduction of AChE >25%), and 21% chronically poisoned (>66% AChE reduction). Using the medical test results as benchmarks, we find that farmers' self-reported symptoms have very weak associations with actual poisoning. To investigate the possible determinants of pesticide poisoning, a probit model was constructed with pesticide amount, toxicity, training, and the use of protective measures as explanatory variables. The results indicate that although the absolute amount of pesticides used does not increase the probability of poisoning, a 1% increase in the use of highly hazardous pesticides (WHO Ia or Ib) increases the probability of poisoning by 3.9% and an increased use of protective measures decreases the probability of poisoning by 44.3%. We also find significant provincial differences in poisoning incidence after we control for individual factors. The provincial effects highlight the potential importance of negative externalities, and suggest that future research on pesticide-related damage should include information on local water, air and soil contamination.

Adolescent↗
PubMed2004

The potential of pesticides to contaminate the groundwater resources of the Axios river basin in Macedonia, Northern Greece. Part I. Monitoring study in the north part of the basin.

The Axios river basin is an area of high agricultural importance for Macedonia, Northern Greece. High priced crops such as cotton, corn, sugarbeets, vegetables and rice are rotated with cereals and alfalfa and thus a great variety of pesticides are used annually for the control of pests and diseases. Moreover, the groundwater resources of the specific area constitute the main source of potable water for the surrounding cities and villages. Therefore, a study was initiated to investigate the probable risks of groundwater contamination with pesticides. The leaching of pesticides from agricultural soils was monitored in the phreatic horizon as well as in soil water samples collected with suction lysimeters. In parallel studies, the presence of pesticides in the irrigation water and the water of Axios river was also monitored. Pesticides like carbofuran, atrazine, alachlor and prometryne, which were regularly applied in the northern part of the basin during 1992-1994 were detected at concentrations occasionally exceeding 1 microg/l in soil water from the deeper soil layers and in the phreatic horizon. Residues of pesticides others than the ones applied in the studied area like propanil, terbufos and paraoxon-methyl were also detected at the deeper soil layers and in the phreatic horizon. The latter pesticides were also detected at significant concentrations in the irrigation water which mainly consisted of riverine water. The lack of an independent soil draining system and the use of riverine water for irrigation purposes resulted in the redistribution of residual amounts of these pesticides in the phreatic horizon beneath the agricultural area.

Agriculture↗
PubMed2006

Water quality and macroinvertebrate community response following pesticide applications in a banana plantation, Limon, Costa Rica.

Pesticides used in banana production may enter watercourses and pose ecological risks for aquatic ecosystems. The occurrence and effects of pesticides in a stream draining a banana plantation was evaluated using chemical characterization, toxicity testing and macrobenthic community composition. All nematicides studied were detected in the surface waters of the banana plantation during application periods, with peak concentrations following applications. Toxicity tests were limited to the carbofuran application and no toxicity was observed with the acute tests used. However, since pesticide concentrations were generally below the lowest LC50 value for crustaceans but above calculated aquatic quality criteria, there remains a risk of chronic toxicity. Accurate ecological assessments of pesticide use in banana plantations are currently limited by the lack of local short-term chronic toxicity tests and tests using sensitive native species. Relatively constant levels of four pesticides (imazalil, thiabendazole, chlorpyrifos and propiconazole), which had toxic effects according to the 96h hydra and 21d daphnia chronic test, were recorded in the effluent of the packing plant throughout the study, indicating that the solid waste trap used in this facility was not effective in eliminating toxic chemicals. Certain taxa, such as Heterelmis sp. (Elmidae), Heteragrion sp. (Megapodagrionidae, Odonata), Caenis sp. (Caenidae, Ephemerotera), and Smicridea sp. (Hidropsychidae, Trichoptera), were more abundant at reference sites than in the banana farm waters, and may be good candidates for toxicity testing. Multivariate analyses of the macroinvertebrate communities clearly showed that the banana plantation sites were significantly different from the reference sites. Moreover, following the pesticide applications, all the banana plantation sites showed significant changes in community composition, with the same genera being affected at all sites and for all pesticides (terbufos, cadusafos and carbofuran). Consequently, the results presented here show that multivariate analysis of community composition was more sensitive in distinguishing pesticide effects than the toxicity tests and richness and composition measures used. We conclude that monitoring macroinvertebrate communities can be a powerful tool in the assessment of ecological effects of banana production.

Agriculture↗
PubMed2006

Modelling of the long term fate of pesticide residues in agricultural soils and their surface exchange with the atmosphere: Part I. Model description and evaluation.

Sources of pesticides in the atmosphere can be releases of new material through current use, or emission/reemission from soil residues resulting from historical use. It is the latter aspect, soil residues, that is the focus of this study. This paper describes the application of a simple coupled atmosphere-soil pesticide exchange model that can assist in the interpretation of soil residue and air concentration measurements, and in the projection of short period field measurements to larger spatial scales and longer time periods. Only dry gaseous exchange (emission and deposition) between bare agricultural lands and the atmosphere is modelled. Wet deposition and particle associated deposition of pesticide are not included. Model results are compared with published co-located air and soil pesticide concentration measurements made on agricultural lands in the southern U.S. that have soil residues of lindane and the following six highly persistent pesticides: cis-, trans-chlordane, p,p'-DDE, dieldrin, trans-nonachlor and toxaphene. The study results show: (i) that measured air concentrations of toxaphene and p,p'-DDE above agricultural soils in the southern U.S. can be attributed to emissions due to local soil residues of these pesticides rather than to the regional background air concentrations; (ii) that both soil emissions and background air concentrations of dieldrin contribute significantly to the measured air concentrations; (iii) that measured air concentrations of cis- and trans-chlordane as well as trans-nonachlor and lindane are mainly due to the regional background with little contribution from local soil residues. An analysis of modelled summer day and night average soil-air exchange fluxes shows that toxaphene and p,p'-DDE soil residues are strong sources of emission to the atmosphere during both the day and night while the chlordanes, trans-nonachlor, lindane and dieldrin are deposited from the atmosphere to the soil during the night hours and emitted to the atmosphere during the day time. This result illustrates the model's capability to simulate the processes that lead to the 'grasshopper' effect whereby persistent pesticides in soils can be transported in the atmosphere by successive periods of emission and deposition to terrestrial surfaces. In the second part to this paper, the model is used to study the trends of pesticide residues and air concentrations over a twenty year period.

Agriculture↗
PubMed2006

Impacts of climate change on the fate and behaviour of pesticides in surface and groundwater--A UK perspective.

Over the last two decades significant effort has been dedicated to understanding the fate and transport of pesticides in surface water and groundwater and to use this understanding in the development of environmental policy and regulation. However, there have been few studies that have investigated the relationships between pesticides and climate change, and where this work has been undertaken it has principally been in relation to the impacts of climate change on agricultural production rather than in the context of environmental protection. This study addresses that gap by reviewing how climate change may impact the fate and transport of pesticides in surface and groundwaters as a pre-cursor to quantitative studies. In order to structure the review, we have adopted a source-pathway-receptor approach where climate sensitivities of pesticide source terms, environmental pathways and receptors are reviewed. The main climate drivers for changing pesticide fate and behaviour are thought to be changes in rainfall seasonality and intensity and increased temperatures, but the effect of climate change on pesticide fate and transport is likely to be very variable and difficult to predict. In the long-term, indirect impacts, such as land-use change driven by changes in climate, may have a more significant effect on pesticides in surface and groundwaters than the direct impacts of climate change on pesticide fate and transport. The review focuses on climate change scenarios and case studies from the UK; however, the general conclusions can be applied more widely.

Agriculture↗
PubMed2003

Evaluation of two-dimensional gas chromatography-time-of-flight mass spectrometry for the determination of multiple pesticide residues in fruit.

In recent years, comprehensive two-dimensional gas chromatography (GC x GC) has attained increasing attention for its outstanding separation potential and capability to solve demanding analytical tasks. Trace level analysis of pesticides residues in complex food matrices represents such a demanding task. For some commodities, such as baby food, the requirements on method detection limits are very strict and the unambiguous confirmation of the pesticide presence based on mass spectrometric detection is required. In this work, GC x GC coupled to time-of-flight mass spectrometry (TOF MS) has been evaluated for the determination of pesticides residues in fruit samples. Twenty modern pesticides with a broad range of physico-chemical properties were analysed in apple and peach samples. It has been demonstrated that the application of comprehensive two-dimensional gas chromatography brings distinct advantages such as enhanced separation of target pesticides from matrix co-extracts as well as their improved detectability. The limits of detection of the pesticides comprised in the study (determined at S/N = 5) ranged from 0.2 to 30 pg, injected with the exception of the last eluted deltamethrin, for which 100 pg could be detected. When compared to one-dimentional GC-TOF MS analysis under essentially the same conditions the detectability enhancement was 1.5-50-fold. Full mass spectral information by time-of-flight mass spectrometry and the deconvolution capability of the dedicated software allowed for reliable identification of most pesticides at levels below 0.01 mg/kg (< 10 pg injected) in fruit. Performance characteristics of the GC x GC-TOF MS method, such as linearity of calibration curves, repeatability of (summed) peak areas, as well as repeatability of first and second dimension retention times, were shown to fully satisfy the requirements for trace level analysis of the pesticide residues in food.

Fruit↗
PubMed2002

Sister chromatid exchange and proliferative rate index in the longitudinal risk assessment of occupational exposure to pesticides.

At present, there are more than 1,000 chemicals classified as pesticides and many reports have shown that some of them have genotoxic properties. In the present longitudinal study, possible genetic damage on a population of workers occupationally exposed to a mixture of pesticides by using sister chromatid exchange (SCE) analysis has been evaluated. As an additional cytogenetic parameter, the proportion of lymphocytes that undergo one, two or three cell divisions as well as proliferative rate index have been determined. This study was performed on the exposed group of workers employed in pesticide production, simultaneously exposed to a complex mixture of pesticides (atrazine, alachlor, cyanazine, 2,4-dichlorophenoxyacetic acid, and malathion). The blood samples of the exposed subjects were collected in three different periods: before the beginning of the new pesticide production period, after 8 months of everyday work in the pesticide production, and 8 months after the removal of subjects out of the production. In all three samplings, the mean value of SCE and number of cells with high sister chromatid exchange frequency (HFC) in the exposed group was significantly higher in the comparison with the control group. There were no differences in the proliferative rate index (PRI) between the control and exposed group, regardless of the sampling period. In both groups examined, the majority of lymphocytes were found in the second cell division, following cultivation. These results suggest that the increase in the number of SCE found in the exposed subjects is not the result of either cytotoxic or epigenetic action of pesticide mixture, but chronic occupational exposure to mixture of pesticides.

Adult↗
PubMed1999

Agricultural pesticides threaten the ecological integrity of northern prairie wetlands.

The northern Great Plains of North America has millions of small wetlands, and these are often dispersed through cultivated fields. We investigated relationship between pesticide occurrence and precipitation in selected wetlands in a 30.4 x 10(4) km2 area of the Great Plains with relatively uniform farming practices and 1,777,600 wetlands (southern Saskatchewan, Canada). By early July after pesticides have been applied to crops, the mean number of pesticides detected in wetlands ranged from 1.8 in regions with little precipitation (< 21 mm rain during the previous 15 days) to 3.2 in regions under higher rainfall (> 90 mm). The proportion of wetlands in which at least one pesticide exceeded Canadian guidelines for the protection of aquatic life increased from 0% to 60% over this same precipitation range. The maximum number of pesticides detected in a single wetland was six. Concentration of lindane in wetlands increased with increasing precipitation. Using geographic information on rainfall, wetland densities, area seeded to crops, and region specific relationships between pesticides and precipitation, we estimated the number of wetlands in Saskatchewan with elevated levels of pesticides. In early July, during 3 of the 6 years, the number of wetlands subjected to pesticide levels that exceeded guidelines for the protection of aquatic life was significant, ranging from 152,000 to 424,000 wetlands or 9-24%, respectively, of the total. Lindane and triallate exceeded the guidelines most frequently.

Agriculture↗
PubMed2003

Evaluation of toxicity of the pesticides, chlorpyrifos and arsenic, in the presence of compost humic substances in aqueous systems.

An improved understanding of pesticide toxicity in natural systems can have important consequences for pesticide management and remediation strategies for contaminated areas. The interaction between humic substances extracted from compost natural organic matter and both organic and inorganic pesticides was evaluated for its effect on the toxicity of pesticides in the aqueous phase. The toxicity of contaminants was measured using the Microtox toxicological bioassay. Solutions containing concentrations ranging from 2 to 42 mg C/l of humic substance extracted from a South Texas compost were added to concentrations of the organic pesticide, chlorpyrifos, and toxicity reduction ranging from 50 to 100% was demonstrated. Different concentrations of arsenic ranging from 0.5 to 5 mg/l were also associated with three different concentrations of humic substances and the arsenic toxicity was consistently reduced by a factor of 100%. These results demonstrate a significant relationship between humic substance interactions with organic and inorganic pesticides, and pesticide toxicity in natural systems, and may also suggest a mechanism for pesticide toxicity reduction in natural waters through compost humic addition for contaminated groundwaters and surface waters.

Arsenic↗
PubMed2003

Farm pesticides: outcomes of a randomized controlled intervention to reduce risks.

BACKGROUND: In response to the multiple health risks that farm pesticide applicators experience and the need for controlled trials to evaluate prevention programs, this study tested the effects of a small-group educational intervention designed to increase personal protective equipment (PPE) use and to reduce direct pesticide exposure. DESIGN: A randomized controlled design was used with random selection of participants, random assignment to intervention and control groups, and baseline and postintervention assessments. SETTING/PARTICIPANTS: Four hundred Wisconsin dairy farmers certified to apply pesticides to field crops were recruited to participate over a 1-year evaluation period. INTERVENTION: Three-hour educational sessions were conducted with approximately 100 randomly assigned participants. Sessions targeted four educational messages: (1) existing evidence of excess cancers among farmers, (2) simulation of pesticide exposure presented through slide show and description, (3) feedback of self-reported data collected from the farmers reporting on frequency of exposure and gear use, and (4) cognitive behavioral strategies that can be adopted to reduce pesticide hazards. MAIN OUTCOME MEASURES: A change in use of required protective equipment use during application and self-reported dermal exposure were evaluated in the control and intervention groups postintervention. RESULTS: Six-month postintervention analyses showed that an educational intervention had significant effects on the use of gloves and gear during the most recent application and an actual reduction in the total number of pesticides used. However, the intervention did not have a significant impact on achieving full PPE compliance nor in reducing the amount of self-reported dermal pesticide exposure during the most recent application reported by applicators. CONCLUSIONS; This one-time educational intervention successfully increased protective equipment use. However, more-intensive programs are needed to achieve greater reductions in personal pesticide exposure.

Agricultural Workers' Diseases↗
PubMed2006

Quantifying the effect of soil moisture on the aerobic microbial mineralization of selected pesticides in different soils.

A standardized quantitative approach was developed to reliably elucidate the effect of increasing soil moisture on pesticide mineralization. The mineralization of three aerobically degradable and chemically different 14C-labeled pesticides (isoproturon, benazolin-ethyl, and glyphosate) was studied under controlled conditions in the laboratory at an identical soil density of 1.3 g cm(-3). The agricultural soils used are characterized by (i) large variations in soil texture (sand content 4-88%) and organic matter content (0.97-2.70% org. C), (ii) fairly diverse soil-water retention curves, and (iii) differing pH values. We quantified the effect of soil moisture on mineralization of pesticides and found that (i) at soil water potential < or = -20 MPa minimal pesticide mineralization occurred; (ii) a linear correlation (P < 0.0001) exists between increasing soil moisture (within a soil water potential range of -20 and -0.015 MPa), and increased relative pesticide mineralization; (iii) optimum pesticide mineralization was obtained at a soil water potential of -0.015 MPa, and (iv) when soil moisture approximated water holding capacity, pesticide mineralization was considerably reduced. As both selected pesticides and soils varied to a large degree, we propose that the correlation observed in this study may be also valid in the case of aerobic degradation of other native and artificial organic compounds in soils.

Aerobiosis↗
PubMed2001

Potential contributions of smectite clays and organic matter to pesticide retention in soils.

Soil organic matter (SOM) is often considered the dominant sorptive phase for organic contaminants and pesticides in soil-water systems. This is evidenced by the widespread use of organic-matter-normalized sorption coefficients (K(OM)) to predict soil-water distribution of pesticides, an approach that ignores the potential contribution of soil minerals to sorption. To gain additional perspective on the potential contributions of clays and SOM to pesticide retention in soils, we measured sorption of seven pesticides by a K-saturated reference smectite clay (SWy-2) and SOM (represented by a muck soil). In addition, we measured the adsorption of atrazine by five different K-saturated smectites and Ca-saturated SWy-2. On a unit mass basis, the K-SWy-2 clay was a more effective sorbent than SOM for 4,6-dinitro-o-cresol (DNOC), dichlobenil, and carbaryl of the seven pesticides evaluated, of which, DNOC was sorbed to the greatest extent. Atrazine was sorbed to a similar extent by K-SWy-2 and SOM. Parathion, diuron, and biphenyl were sorbed to a greater extent by SOM than by K-SWy-2. Atrazine was adsorbed by Ca-SWy-2 to a much lesser extent than by K-SWy-2. This appears to be related to the larger hydration sphere of Ca(2+) (compared to that of K(+)) which shrinks the effective size of the adsorption domains between exchangeable cations, and which expands the clay layers beyond the apparently optimal spacing of approximately 12.2 A for sorption of aromatic pesticide structures. Although a simple relation between atrazine adsorption by different K-smectites and charge properties of clay was not observed, the highest charge clay was the least effective sorbent; a higher charge density would result in a loss of adsorption domains. These results indicate that for certain pesticides, expandable soil clays have the potential to be an equal or dominant sorptive phase when compared to SOM for pesticide retention in soil.

Absorption↗
PubMed2002

Subcritical water extraction to evaluate desorption behavior of organic pesticides in soil.

We evaluated the feasibility of extracting organic pesticides in soil using a hot-water percolation apparatus at 105 degrees C and 120 kPa pressure. Efficiency of the method was assessed by extracting six selected pesticides (acetochlor, atrazine, diazinon, carbendazim, imidacloprid, and isoproturon) from previously equilibrated soil at 13.6-65.8 mg/kg concentration range. Studies were performed on brown forest soil with clay alluviation (Luvisol). The method developed was compared to the traditional batch equilibrium method in terms of desorbed amount of pesticides from soil and extraction time. Pesticides in the liquid phase from the batch sorption experiment and in the effluent from the hot-water percolation were quantified by high-performance liquid chromatography with UV detection. The results of the percolation experiment are in close correlation with those of the conventional soil testing method. Desorbed quantities by hot-water percolation were 85% acetochlor, 62% atrazine, 65% carbendazim, 44% diazinon, 95% imidacloprid, and 84% isoproturon, whereas using batch equilibrium method 101, 66, 64, 37, 81, and 90% were desorbed, expressed as the percentage of the adsorbed amount of pesticide on soil following equilibration. The average time for hot-water extraction was 3.45 min, in contrast to the 16 h time consumption of the traditional batch method. The effect of temperature on stability of selected compounds was also evaluated using pesticide-spiked sand without soil. Recoveries of analytes ranged between 84.6 and 91.1% with reproducibility of 7.9-10.2%, except for diazinon, for which recovery was 59.4% with 14.4% relative standard deviation since decomposition occurred at elevated temperature. The percolation process has been described by a first-order kinetic equation. The parameters calculated from the equation provide an opportunity to estimate the amount of compound available for desorption, the rate of desorption processes in the studied soil-pesticide-water system, and modeling the leaching process to obtain additional information on the environmental behavior of the examined pesticide.

Atrazine↗
PubMed2004

Multiresidue determination of pesticides in soil by gas chromatography-mass spectrometry detection.

An analytical multiresidue method for the simultaneous determination of various classes of pesticides in soil was developed. Pesticides were extracted from soil with ethyl acetate. Soil samples were placed in small columns, and the extraction was carried out assisted by sonication. Pesticides were determined by gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode. 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 0.2, 0.1, and 0.05 microg/g fortification levels of each pesticide, and the recoveries obtained ranged from 87.0 to 106.2% with a relative standard deviation between 2.4 and 10.6%. Good resolution of the pesticide mixture was achieved in approximately 41 min. The detection limits of the method ranged from 0.02 to 1.6 microg/kg for the different pesticides studied. The developed method is linear over the range assayed, 25-1000 microg/L, with determination coefficients >0.999. The proposed method was used to determine pesticide levels in real soil samples, taken from different agricultural areas of Spain, where several herbicides and insecticides were found.

Gas Chromatography-Mass Spectrometry↗
PubMed2004

Leaching of pesticides from biobeds: effect of biobed depth and water loading.

Pesticides may be released to farmyard surfaces as a result of spillages, leakages, and the decontamination of tractors and sprayers. Biobeds can be used to intercept and treat contaminated runoff, thus minimizing losses to the environment. Previous studies using lined and unlined biobeds showed that water management was the limiting factor for both systems. While lined biobeds effectively retained pesticides, the system rapidly became water logged and degradation was slow. Studies using unlined biobeds showed that >99% of the applied pesticides were removed by the system, with a significant proportion degraded within 9 months. However, peak concentrations of certain pesticides (Koc < 125) were unacceptable to the regulatory authorities. These experiments were designed to optimize the design and management of unlined biobeds. Experiments performed to investigate the relationship between biobed depth and water loading showed that biobeds need to have a minimum depth of 1-1.5 m. The surface area dimension of the biobed depends on the water loading, which is controlled by the nature and frequency of pesticide handling activities on the farm. Leaching losses of all but the most mobile (Koc < 15) pesticides were <0.32% of the applied dose from 1.5 m deep biobeds subject to a water loading of 1175 L m(-2). These were reduced to <0.06% when a water loading of 688 L m(-2) was applied and down to <0.0001% for a water loading of 202 L m(-2). On the basis of these data, a 1.5 m deep biobed, subject to a maximum water loading of 1121 L m(-2) and with a surface area of 40 m(2) should be able to treat < or =44000 L of pesticide waste and washings such that the average concentration of all pesticides, other than those classified as very mobile, does not exceed 5 microg L(-1). This level of treatment can be improved by further reduction in the hydraulic loading.

Agriculture↗
PubMed2004

Multiresidue determination of pesticides in malt beverages by capillary gas chromatography with mass spectrometry and selected ion monitoring.

A method was developed to determine pesticides in malt beverages using solid phase extraction on a polymeric cartridge and sample cleanup with a MgSO4-topped aminopropyl cartridge, followed by capillary gas chromatography with electron impact mass spectrometry in the selected ion monitoring mode [GC-MS(SIM)]. Three GC injections were required to analyze and identify organophosphate, organohalogen, and organonitrogen pesticides. The pesticides were identified by the retention times of peaks of the target ion and qualifier-to-target ion ratios. GC detection limits for most of the pesticides were 5-10 ng/mL, and linearity was determined from 50 to 5000 ng/mL. Fortification studies were performed at 10 ng/mL for three malt beverages that differ in properties such as alcohol content, solids, and appearance. The recoveries from the three malt beverages were greater than 70% for 85 of the 142 pesticides (including isomers) studied. The data showed that the different malt beverage matrixes had no significant effect on the recoveries. This method was then applied to the screening and analysis of malt beverages for pesticides, resulting in the detection of the insectide carbaryl and the fungicide dimethomorph in real samples. The study indicates that pesticide levels in malt beverages are significantly lower than the tolerance levels set by the United States Environmental Protection Agency for malt beverage starting ingredients. The use of the extraction/cleanup procedure and analysis by GC-MS(SIM) proved effective in screening malt beverages for a wide variety of pesticides.

Beer↗
PubMed2001

Pesticides and nitrate in groundwater and rainwater in the Province of Limburg in The Netherlands.

The purpose of this study was to investigate the occurrence of high levels of pesticides in groundwater and rainwater in The Province of Limburg in The Netherlands. In groundwater samples in particular the presence of triazines--atrazine, simazine and propazine--was observed; besides these pesticides, dieldrin has also been observed. Atrazine and simazine were found to exceed the groundwater standard of 100 ng L(-1). In the rainwater samples, the presence of 13 of 23 different analyzed pesticides was observed. A number of pesticides were found in high concentrations; e.g. atrazine (>200 ng L(-1)). Two pesticides detected in rainwater (beta+gamma-HCH and atrazine) were found to exceed the groundwater standard. Seven pesticides in rainwater were found to exceed the target value and three pesticides the maximum tolerable risk value (DDT, heptachlor and heptachlorepoxide A), which are used as ecotoxicological standards in The Netherlands. Nitrate in 15 of 16 analyzed natural springs was found to exceed the guideline value for nitrate in drinking water of 50 mg L(-1), up to levels of about 200 mg L(-1). Nitrate concentrations in rainwater samples were observed up to 4.5 mg L(-1). A risk analysis of exposure to high pesticide levels in groundwater or rainwater has been performed using the model HESP. For atrazine levels due to deposition of rainwater in two different locations, exceedance of the T.D.I. level of 0.5 microg kg(-1) day(-1) based on WHO criteria was observed for children using both an urban and a rural scenario and use of groundwater as drinking water.

Environmental Monitoring↗
PubMed2004

Effects of the agricultural pesticides atrazine, chlorothalonil, and endosulfan on South Florida microbial assemblages.

One of the most impacted watersheds in the US in terms of pesticide usage is South Florida, which drains through a series of canals into the Florida Everglades and Florida Bay. Single species responses to pesticide exposure are well documented; however, little is known about community level responses to pesticides, especially at lower trophic levels. Microbial assemblages at two sites along the C-111 canal in the Dade County agricultural area in October 1999 (wet season, limited pesticide application) and in February 2000 (dry season, heavy pesticide application) were colonized onto artificial substrates, transported to the laboratory and exposed to atrazine (20 and 200 microg/l), chlorothalonil (2 and 20 microg/l), or endosulfan (1 and 10 microg/l). Structural and functional responses were measured at 24 h and 168 h post-dose. Regardless of site, season or exposure time, the highest atrazine dose (200 microg/l) significantly reduced chlorophyll a, phototrophic carbon assimilation and bacterial biomass, but stimulated heterotrophic bacterial productivity. Chlorophyll a was also significantly reduced by 20 microg/l atrazine (October only). The lowest endosulfan dose (1 microg/l) significantly increased phototrophic carbon assimilation. The highest chlorothalonil dose (20 microg/l) stimulated heterotrophic bacterial productivity (October only). An overall decrease in the number of protist taxa was observed with all pesticide treatments. Atrazine significantly decreased the relative abundance of chlorophytes and chrysophytes and increased the number of diatom and heterotrophic protist taxa. Chlorothalonil significantly increased the relative abundance of diatoms and chlorophytes, while chrysophytes and heterotrophic protists decreased. Endosulfan also significantly reduced diatom abundance, as well as decreasing the number of chrysophyte, cryptophyte and dinoflagellate taxa. Although previous agricultural pesticide exposure was greater at site C than at site E, the microbial assemblages at site C did not exhibit increased resistance to a subsequent dose of the pesticides.

Agriculture↗