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PubMed2000

Genotoxicity of two novel pesticides for the earthworm, Eisenia fetida.

In this paper, several studies were conducted to evaluate the genotoxicity of two pesticides, Imidacloprid and RH-5849, for earthworm (Eisenia fetida). Earthworms were exposed in different exposure systems to evaluate their acute toxicity and the genotoxicity of the two pesticides was evaluated by using the method of sperm deformity assessment, micronucleus test of root tip cells in Vicia faba, a mouse bone-marrow micronucleus test, and comet assay. LC(50) (interpolated concentration at which 50% mortality of test population occurs) for earthworms varied in different exposure systems. The results indicated that Imidacloprid was consistently more toxic than RH-5849 in all exposure systems. In this study, sperm deformity test was used to detect the potential adverse influences of pesticides on the reproduction of earthworms. The results demonstrated that significant induction of sperm deformity (p<0.01) and a dose-effect relationship displayed at Imidacloprid concentrations higher than 0.5 mg/kg dry soil. However, the sperm deformity frequency of groups exposed to RH-5849 did not show significant difference (p>0.05) from the control until the dose reached 100 mg/kg dry soil. The results of the V. faba micronucleus tests showed that micronuclei frequency of the exposed group did not show significant difference (p>0.05) from the control until the concentration of Imidacloprid and RH-5849 reached 100 mg/ml. The results of the mouse bone-marrow micronuclei test also indicate that two pesticides did not show significant effects (p>0.05) on the micronuclei frequency in mice bone-marrow cells until the dose reached 100 mg/kg for Imidacloprid and 300 mg/kg for RH-5849 (2/3 LD(50)). Although no genotoxicity was detected by using the micronucleus tests, the results of the comet assay showed that the two pesticides induce significant DNA damage (p<0.01) in earthworms and dose-effect relationships were displayed. The 'earthworm comet assay' is a rapid and sensitive way to screen chemicals or terrestrial environments for their DNA-damaging properties.

Journal Article↗
PubMed2000

Bound pesticide residues in soils: a review.

This article is a review of the current state of knowledge regarding the formation and biological/environmental significance of bound pesticide residues in soils. We begin by defining various terms used in our discussions and identifying the types/classes of pesticides which may be added to soil and interact with it. We then consider various soil properties and aspects of land management which will influence the nature and degree of the soil-pesticide association and discuss the possible physical and chemical binding mechanisms. We then move on to consider the role of microorganisms and other forms of soil biota in bound residue formation and the bioavailability of soil-borne pesticide residues. The review ends with a consideration of the significance of bound pesticide residues.

Journal Article↗
PubMed1997

Comparative in vitro and in vivo protein kinase C activation by selected pesticides and transition metal salts.

Various pesticides and transition metals induce oxidative deterioration of biological macromolecules. Protein kinase C (PKC) may mediate these effects. However, no information is available regarding whether these xenobiotics can modulate PKC which is a critical event signaling the increase in endothelial permeability and cell proliferation. Female Sprague-Dawley rats were treated p.o. with two 0.25 LD50 doses of selected pesticides and transition metal salts at 0 and 21 h, and killed at 24 h. PKC activities were measured in liver and brain tissues. Cultured PC-12 cells were incubated for 24 h with 50, 100 or 200 nM concentrations of these pesticides, while 0.20, 0.40 or 0.60 microM concentrations of cadmium chloride (Cd(II)) and sodium dichromate (Cr(VI)) salts were employed. PKC activations were observed in the hepatic and brain cytosol fractions by all xenobiotics. Approximately 1.4- to 2.0-fold and 1.6- to 3.5-fold increases in PKC activity in the hepatic and brain cytosol fractions were observed, respectively. In the hepatic tissues, the greatest increases in activities were observed with TCDD, chlorpyrifos, endrin and Cd(II), while chlorpyrifos and fenthion exerted the greatest increases in the brain tissues. In cultured PC-12 cells, the greatest activation of PKC was observed primarily with 100-nM concentrations of the pesticides. The maximum effects were induced by chlorpyrifos, fenthion, Cd(II) and Cr(VI) salt. The results clearly indicate that pesticides as well as Cd(II) and Cr(VI) salts can modulate a vital component of the cell signaling pathway, namely PKC activity. PKC may be a target of free radicals and oxidative stress, leading to altered cell proliferation and differentiation.

Animals↗
PubMedDate not supplied

Six high-priority organochlorine pesticides, either singly or in combination, are nonestrogenic in transfected HeLa cells.

There have been increasing concerns that environmental chemicals may adversely affect the health of humans and wildlife by acting as endocrine modulators. These concerns have been augmented by the realization that human exposure occurs not just to single chemical agents, but typically to mixtures of chemicals that could exhibit estrogenic activity qualitatively and/or quantitatively different from that of individual components. To address these concerns, we have evaluated the ability of six organochlorine pesticides (4, 4'-DDT, 4,4'-DDD, 4,4'-DDE, aldrin, dieldrin, or endrin, all classified high priority by ATSDR) to modulate transcriptional activation of an estrogen-responsive reporter gene in transfected HeLa cells. In these assays, HeLa cells cotransfected with an expression vector encoding estrogen receptor and an estrogen-responsive chloramphenicol acetyltransferase (CAT) reporter plasmid were exposed to these pesticides individually and in defined combinations. While estradiol consistently elicited 10- to 23-fold dose-dependent inductions in these assays, the six organochlorine pesticides showed no detectable dose-related response when tested individually. When tested in binary combinations, the pesticide mixtures showed no additional estrogenicity. Thus, the pesticides tested, singly or as mixtures, showed virtually no evidence of estrogenicity.

Aldrin↗
PubMedDate not supplied

Influence of organochlorine pesticides on maturation and postfertilization development of bovine oocytes in vitro.

The aim of this study was to perform a dose-response test to determine whether bovine oocytes exposed to dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (gammaHCH), or methoxychlor (MXC) in vitro would exhibit changes in maturation rates, cleavage rates at Day 2, or blastocyst rates at Day 7 to 8 after fertilization in vitro (IVF). All three pesticides affected maturation and degeneration rates in a dose-dependent manner, but to different extents. Higher concentrations of pesticides were associated with higher rates of chromatin degeneration. Because the maturation of bovine oocytes was depressed in a dose-dependent manner, the fertilizability and further embryonic development of in vitro matured oocytes was studied at the lowest previously tested concentration (7.25 microg/mL) only. No significant difference in fertilization rates was seen between unexposed control and treated groups. The cleavage rates did not differ among groups 48 h after IVF. The number of morulae and blastocysts on Day 7 to 8 after IVF, which is commonly used as a parameter for normal development, was significantly different between control and DDT- and gammaHCH-treated groups, but not between the control and MXC groups. The pesticides did not differ significantly among themselves. These results show that the tested pesticides decrease the rate of normal oocyte maturation in vitro in a dose-dependent manner. The effect of the lowest concentration of pesticides is seen only after Day 7 of embryo development.

Animals↗
PubMed2001

Emission of chiral organochlorine pesticides from agricultural soils in the cornbelt region of the U.S.

Several organochlorine pesticides are chiral molecules manufactured as racemic mixtures. Past research has shown that selective degradation of pesticide enantiomers by microorganisms occurs resulting in nonracemic signatures in soils. In this work, volatilization of chiral pesticides from soil was investigated to determine if enantioselective breakdown in soils could be used as a source signature to track releases of chiral pesticides to the atmosphere. Air samples were taken directly above agricultural soils at several sites, and enantiomeric signatures were found to be nonracemic following patterns found in the soil. A follow up study at one site showed that for most compounds concentration decreased with increasing height above the soil, while enantiomer fractions for chiral pesticides were similar to that found in the soil, signifying the soil as a source to the air. The enantiomer fractions of ambient air samples from rural nonagricultural areas in the region were also found to be nonracemic.

Agriculture↗
PubMed2002

Influence of rhamnolipids and triton X-100 on the desorption of pesticides from soils.

A rhamnolipid biosurfactant mixture produced by P. aeruginosa UG2 and the surfactant Triton X-100 were tested for their effectiveness of enhancing the desorption of trifluralin, atrazine, and coumaphos from soils. Sorption of both surfactants by the soils was significant and adequately described by the Langmuir-type isotherm. Values of maximum sorption capacity (Qmax) and Langmuir constant (Klang) did not correlate with the amount of soil organic matter. Our results indicate that clay surfaces play an important role in the sorption of surfactants. When surfactant dosages were high enough to reach soil saturation and maintain an aqueous micellar phase, pesticide desorption was only enhanced. At dosages below soil saturation, surfactants sorbed onto soil, increasing its hydrophobicity and enhancing the sorption of the pesticides by a factor of 2. Similar values of water-soil partition coefficients (Ksol*) for aged and fresh added pesticides to soils indicate that the aging process used did not significantly after the capability of either surfactant to desorb the pesticides. A model able to estimate equilibrium distributions of organic compounds in soil-aqueous-micellar systems was tested against experimental results. The determined organic carbon partition coefficients, Koc values, indicate that, on a carbon normalized basis, sorbed Rh-mix is a much better sorbent of pesticides than TX-100 or soil organic matter. These results have significant implications on determining the effectiveness of surfactants to aid soil remediation technologies.

Adsorption↗
PubMedDate not supplied

Functionalized surfaces for optical biosensors: applications to in vitro pesticide residual analysis.

Functionalized biosensing surfaces were developed for chemiluminescent immunoassay of pesticides. Two approaches to construct functionalized surfaces were tested: (i) pesticide is immobilized to the surface and interacts with a labeled antibody; (ii) antibody is immobilized and interacts with a labeled pesticide. As labels alkaline phosphatase and peroxidase were used with their corresponding substrates CSPD and luminol, respectively. Light produced by chemiluminescent substrate was detected by a thermoelectrically cooled CCD camera or a photomultiplier. The best detection limit 0.00001 ng/ml was obtained using antibodies immobilized to dextran-enhanced surface. Completely renewable surface was obtained using reversible lectin-monosaccharide interaction, one surface was used for 200 analyses without any loss of binding capacity. Most favorable stability and cost per analysis was achieved with molecularly imprinted polymer (MIP) instead of antibody. The functionalized biosensing surfaces were prepared to detect 2,4-dichlorophenoxyacetic (2,4-D) acid as a model pesticide. The developed concepts are, however, generally applicable to other pesticides and to other optical formats, e.g. optical fiber.

Journal Article↗
PubMedDate not supplied

Residential environmental measurements in the national human exposure assessment survey (NHEXAS) pilot study in Arizona: preliminary results for pesticides and VOCs.

A major objective of the National Human Exposure Assessment Survey (NHEXAS) performed in Arizona was to conduct residential environmental and biomarker measurements of selected pesticides (chlorpyrifos, diazinon), volatile organic compounds (VOCs; benzene, toluene, trichloroethene, formaldehyde, 1,3-butadiene), and metals for total human exposure assessments. Both personal (e.g., blood, urine, dermal wipes, 24 h duplicate diet) and microenvironmental (e.g., indoor and outdoor air, house dust, foundation soil) samples were collected in each home in order to describe individual exposure via ingestion, inhalation, and dermal pathways, and to extrapolate trends to larger populations. This paper is a preliminary report of only the microenvironmental and dermal wipe data obtained for the target pesticides and VOCs, and provides comparisons with results from similar studies. Evaluations of total exposure from all sources and pathways will be addressed in future papers. The pesticides and VOCs all showed log-normal distributions of concentrations in the Arizona population sampled, and in most cases were detected with sufficient frequency to allow unequivocal description of the concentration by media at the 90th, 75th, and 50th (median) percentiles. Those combinations of pollutant and media, in which a large fraction of the measurements were below the detection limit of the analysis method used, included trichloroethene, 1,3-butadiene, and formaldehyde in outdoor air; chlorpyrifos and diazinon in outdoor air; and diazinon in dermal and window sill wipes. In general, indoor air concentrations were higher than outdoor air concentrations for all VOCs and pesticides investigated, and VOC levels were in good agreement with levels reported in other studies. In addition, the agreement obtained between co-located VOC samplers indicated that the low-cost diffusional badges used to measure concentrations are probably adequate for use in future monitoring studies. For the pesticides, the median levels found in indoor samples agreed well with other studies, although the levels corresponding to the upper 0.1-1% of the population were considerably higher than levels reported elsewhere, with indoor air levels as high as 3.3 and 20.5 microg/m3 for chlorpyrifos and diazinon, respectively. These data showed excellent correlation (Pearson and Spearman correlation coefficients of 0.998 and 0.998, respectively) between chlorpyrifos in indoor air and in the corresponding dermal wipes, and relatively poor correlation between chlorpyrifos in dust (microg/g or microg/ml) and dermal wipes (Pearson=0.055 microg/g and 0.015 microg/m2; Spearman=0.644 microg/g and 0.578 microg/m2). These data suggest the importance of dermal penetration of semi-volatiles as a route of residential human exposure.

Air Pollutants↗
PubMed2001

Predator-induced stress makes the pesticide carbaryl more deadly to gray treefrog tadpoles (Hyla versicolor).

Global declines in amphibians likely have multiple causes, including widespread pesticide use. Our knowledge of pesticide effects on amphibians is largely limited to short-term (4-d) toxicity tests conducted under highly artificial conditions to determine lethal concentrations (LC50). We found that if we used slightly longer exposure times (10-16 d), low concentrations of the pesticide carbaryl (3-4% of LC50(4-d)) killed 10-60% of gray treefrog (Hyla versicolor) tadpoles. If predatory cues also were present, the pesticide became 2-4 times more lethal, killing 60-98% of tadpoles. Thus, under more realistic conditions of increased exposure times and predatory stress, current application rates for carbaryl can potentially devastate gray treefrog populations. Further, because predator-induced stress is ubiquitous in animals and carbaryl's mode of action is common to many pesticides, these negative impacts may be widespread in nature.

Animals↗
PubMedDate not supplied

Occupational illnesses from cholinesterase-inhibiting pesticides among agricultural applicators in California, 1982-1985.

California pesticide illness investigation reports involving toxicity category I or II organophosphate and carbamate pesticide exposures among agricultural pesticide applicators were reviewed for the years 1982-1985. The pesticides associated with each illness were recorded, and the exposures were classified as chronic, short-term, or accidental. Illnesses were associated with a range of pesticides, including both organophosphates and carbamates in both toxicity categories I and II. Approximately 19% of the illnesses were due to accidents. Overall, the analysis identified a need for improving occupational health surveillance and the regulations governing worker health and safety.

Accidents, Occupational↗
PubMed2006

Estimation of apoptosis and necrosis caused by pesticides in vitro on human lymphocytes using DNA diffusion assay.

Organophosphorus pesticides like monocrotophos, profenofos, chlorpyrifos, and acephate are most commonly used in India for agriculture and public health programs. Previous studies have revealed that at low doses, organophosphorus pesticides not only act as genotoxic agents but also affect several other biochemical pathways. The aim of the current investigation was to assess apoptosis and necrosis caused by these pesticides on human peripheral blood lymphocytes under in vitro conditions using the DNA diffusion assay. Our studies have revealed that all the above pesticides induced apoptosis and necrosis in cultured human peripheral blood lymphocytes in in vitro conditions. The results are statistically significant (p < 0.001). Data on these alterations of immune cells are required for understanding the subchronic effects mediated by pesticides on nontarget organisms.

Apoptosis↗
PubMed1997

A new sensitive cell culture test for the assessment of pesticide toxicity.

A new, simple and sensitive cell culture test for the determination of cytotoxicity of pesticides is described. This test is based on assessment of the growth inhibitory effect of pesticides on the rapidly growing mouse hybridoma cell line 1E6 cultivated in a defined serum-free medium (RPMI-SR3). In addition the cytotoxicity in serum-containing medium was investigated. The results showed that the sensitivity of 1E6 cell towards the toxicity of the pesticides; carbofuran, cypermethrin, lindane, glyphosate and 2,4-D was considerably higher in the serum-free medium than in serum-containing medium. Also IC50 values of these pesticides were compared with LD50 values obtained from the literature. The ratio between the in vitro IC50 and the in vivo LD50 showed that the present cell culture test determine the toxicity of low levels of pesticides with much higher sensitivity than tests based on using animals.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1998

Pesticide concentration variations correlated with well bore volume removal in shallow coastal plain ground water.

The effects of well bore volume removal (Vn) on the concentration of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxy methyl) acetamide] and prometon (6-methoxy-N,N'-bis(1-methylethyl)-1,3,5-triazine-2,4-diamine] in ground water obtained from three monitoring wells installed in the Coastal Plain region of North Carolina was investigated. Seasonal effects were also investigated by conducting the exercise in February and May. In the majority of cases, the lowest pesticide concentrations occurred in the initial well bore volume (V1 = stagnant water). Removal of additional well bore volumes (V2 to V10) from two of the wells resulted in pesticide concentrations that did not vary substantially. This indicates that a representative aquifer sample was obtainable, in most cases from these wells, after removal of the initial well bore volume. In contrast, a third well required the purging of two well bore volumes before a stable alachlor concentration was achieved. Seasonal effects of bore volume removal vs. pesticide concentrations for the three wells were not significant (P > 0.05). It was concluded that a protocol for improved accuracy in pesticide analyses of ground water can be obtained by establishing a pesticide concentration-purging (well bore volume) relationship for each well.

Acetamides↗
PubMed1994

Mammalian toxicology of organophosphorus pesticides.

Organophosphorus compounds have been utilized as pesticides for almost five decades. They continue to be used as insecticides, helminthicides, ascaricides, nematocides, and to a lesser degree as fungicides and herbicides. While they have been and continue to be extremely useful in agricultural pest control throughout the world, their extensive use has led to numerous poisonings of nontarget species, including many human fatalities. The primary acute mammalian toxicity associated with exposure to organophosphorus pesticides results from inhibition of the enzyme acetylcholinesterase. However, other toxicities, some of which are life-threatening but not related to acetylcholinesterase inhibition, have been observed following exposure to certain organophosphorus compounds. The focus of the current review is to summarize the known effects, both cholinergic and noncholinergic, of organophosphorus pesticides in mammals. Included in this summary is a discussion of the metabolic activation of organophosphorus pesticides, since this process plays a critical role in mediating the acute toxicities of many of these pesticides.

Animals↗
PubMed2004

Cancer incidence among pesticide applicators exposed to chlorpyrifos in the Agricultural Health Study.

BACKGROUND: Chlorpyrifos is one of the most widely used insecticides in the United States. We evaluated the incidence of cancer among pesticide applicators exposed to chlorpyrifos in the Agricultural Health Study, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina. METHODS: A total of 54,383 pesticide applicators were included in this analysis. Detailed information on pesticide exposure and lifestyle factors was obtained from self-administered questionnaires completed at the time of enrollment (December 1993-December 1997). Poisson regression analysis was used to evaluate the association between chlorpyrifos exposure and cancer incidence after adjustment for potential confounders. All statistical tests were two-sided. RESULTS: A total of 2070 incident malignant neoplasms were diagnosed through 2001. The rate ratio for all cancers combined among chlorpyrifos-exposed applicators compared with nonexposed applicators was 0.97 (95% confidence interval = 0.87 to 1.08). For most cancers analyzed, there was no evidence of an exposure-response relationship. However, the incidence of lung cancer was statistically significantly associated with both chlorpyrifos lifetime exposure-days (P(trend) = .002) and chlorpyrifos intensity-weighted exposure-days (P(trend) = .036). After adjustment for other pesticide exposures and demographic factors, individuals in the highest quartile of chlorpyrifos lifetime exposure-days (>56 days) had a relative risk of lung cancer 2.18 (95% confidence interval = 1.31 to 3.64) times that of those with no chlorpyrifos exposure. CONCLUSION: Our findings suggest an association between chlorpyrifos use and incidence of lung cancer that deserves further evaluation.

Adult↗
PubMed2001

Agricultural exposure to carbamate pesticides and risk of non-Hodgkin lymphoma.

Recent epidemiological studies have suggested an increased risk of non-Hodgkin lymphoma (NHL) from carbamate insecticide use among farmers. To further explore the possible relationships, we conducted a pooled analysis of three population-based case-control studies conducted in four midwestern states in the United States. A total of 985 white male subjects and 2895 control subjects were included in this analysis. Unconditional logistic regression was used to estimate the association and control for confounding. Compared with nonfarmers, farmers who had ever used carbamate pesticides had a 30% to 50% increased risk of NHL, whereas farmers without carbamate pesticide use showed no increased risk. Analyses for individual carbamate pesticides found a more consistent association with Sevin but not carbofuran, butylate, or S-ethyl dipropylthiocarbamate plus protectant. Among farmers using Sevin, the risk of NHL was limited to those who personally handled the product, those who first used the product for > or = 20 years before their disease diagnosis, and those who used the product for a longer period. These associations persisted after adjusting for other major classes of pesticides. These results suggest an increased risk of NHL associated with carbamate pesticide use, particularly Sevin. Further investigation of the association is warranted.

Adult↗
PubMed1992

Hazards of closed pesticide mixing and loading systems: the paradox of protective technology in the Third World.

In studies in developing countries, closed systems for mechanically mixing and loading hazardous pesticides have been shown to reduce exposure to workers. To evaluate the efficacy of closed systems in preventing worker exposure in the developing world, a cross sectional study was conducted at rural crop dusting airports in the cotton growing region of Nicaragua. Worker exposure was evaluated by measuring the activity of erythrocyte cholinesterase in the field with a new design battery operated colorimeter. The 10 mixer loaders at four airstrips with closed systems were compared with the 16 mixer loaders at four airstrips where pesticides were hand poured. Paradoxically, cholinesterase activity was 1.1 IU/ml blood (95% Cl 0.49-1.8) lower (inhibited) among workers in airstrips with closed systems than among workers hand pouring insecticides, after adjusting for weight of organophosphates sprayed in the past 14 days, and for prior training in safe use of pesticides. Mixer loaders with prior training had cholinesterase activity 0.83 IU (95% Cl 0.30-1.4) higher than untrained workers, and the weight of organophosphates sprayed was also a statistically significant predictor in the model. Unfortunately, management viewed the closed systems primarily as a production tool, rather than as a way to protect workers. Airstrips with closed systems were able to apply an average of 3250 lb organophosphates per worker in the 14 days before the survey compared with 849 lb per worker in airstrips without closed systems. Only three of 10 mixer-loaders at airstrips with closed systems had received formal training in safer use of pesticides. Because of shortage of personnel and transport, it was difficult for the responsible government agencies to train workers adequately and to enforce pesticide health and safety standards at multiple dispersed worksites.

Cholinesterase Inhibitors↗