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PubMed1995

Determination of organophosphorus pesticides and their transformation products in river waters by automated on-line solid-phase extraction followed by thermospray liquid chromatography-mass spectrometry.

The trace-level determination of ten priority organophosphorus (OP) pesticides (e.g., chlorpyrifos-methyl, diazinon, disulfoton, fenthion, fenamiphos) and various transformation products (TPs; e.g., disulfoton sulfoxide, fenthion sulfoxide etc.) using automated on-line solid-phase extraction (SPE) with C18 precolumns followed by LC-MS and thermospray interface with time-scheduled selected-ion monitoring (SIM) was developed. Two main ions (usually [M+H]+ and [M+NH4]+ or [M+CH3CN]+) were used for each pesticide in the positive ion (PI) detection mode, while [M-H]- and [M+HCOO]- ions were used in the negative ion (NI) mode. The proposed method requires 100 ml of sample for a limit of detection (LOD) of 0.01-0.1 microgram/l. Calibration graphs were constructed by preconcentrating 100 ml of water spiked with the pesticide mixture at various concentrations (from 0.025 to 2 microgram/l). Good linearity was observed for most of the analytes studied. The experimental setup described in this paper was applied to study the kinetics of degradation of ten organophosphorus pesticides in spiked river water samples. The different samples were first analyzed by an automated on-line precolumn exchange system (OSP-2) followed by LC with diode array detection. To confirm the identity of the organophosphorus pesticides detected, the samples were then analyzed by automated on-line SPE-LC-MS. The method permitted unequivocal identification of many of the TPs formed during the experiments, e.g., the oxo-derivatives of chlorpyrifos-methyl, temephos and pyridafenthion, fenamiphos sulfoxide. Many of these TPs are here reported for the first time since previously used MS-based techniques were not sensitive enough.

Biodegradation, Environmental↗
PubMed1988

Pesticide use related to cancer incidence as studied in a rural district of Hungary.

General mortality analysis showed an increasing tendency of circulatory diseases in two villages examined. Respiratory diseases and suicide were more frequent in the village with greater pesticide use (village I). The relative risk (RR) of gastric cancer for men is significantly higher in village I (high rate of pesticide use) than in the county as a whole (RR, 1.65; 95% confidence interval (CI), 0.96-2.83) and also in relation to the national data (RR, 3.20; 95% CI, 1.91-5.36). Since the nitrate concentration in the drinking water, the drug consumption, smoking and eating habits are similar in the two villages, and since alcohol consumption is higher in village II (moderate rate of pesticide use), it seems that nitrosable pesticides may play a role in the etiology of stomach cancer. This is supported by the fact that a higher number of gastric cancer cases was found where larger quantities of nitrosable pesticides had been used.

Adult↗
PubMed1992

Biological and chemical interactions of pesticides with soil organic matter.

There is little doubt that organic matter plays a major role in the binding of pesticides in soil, and that this phenomenon is usually the most important cause for interaction of pesticides in the soil environment. Fulvic or humic acids are the chemicals most commonly involved in the binding interactions. Binding can occur with the original pesticide or a transformation product, the reaction being caused by abiotic agents or biotic agents (microbial or plant enzymes). The reactions or processes involved appear to be the same as those responsible for the formation of humic substances, i.e. for the humification process. Binding of pesticides to organic matter can occur by sorption (Van der Waal's forces, hydrogen bonding, hydrophobic bonding), electrostatic interactions (charge transfer, ion exchange or ligand exchange), covalent bonding or combinations of these reactions. Our investigation focused primarily on the binding of substituted phenols and aromatic amines to humus monomers and humic substances. In model reactions, we demonstrated the formation of covalent linkages between pesticides and humus constituents and fulvic or humic acids in the presence of phenol oxidases or clay minerals. With chlorinated phenols and carboxylic acids, it was possible to isolate and identify cross-coupling products and to elucidate the site and type of binding. The binding of chlorinated phenols to humic substances was determined by using 14C-labelled chemicals and by measuring the uptake of radioactivity by the humic material. These experiments provide a base for explaining the formation of bound residues in certain cases and for assuming the toxic potential of the immobilized pollutants.

Adsorption↗
PubMed1987

Impact of pesticides on lipid metabolism in the freshwater catfish, Clarias batrachus, during the vitellogenic phase of its annual reproductive cycle.

Specimens of either sex of the freshwater catfish Clarias batrachus were exposed to safe and sublethal concentrations of an organochlorine, gamma-BHC (2 and 8 ppm), and an organophosphorus compound, malathion (1 and 4 ppm), for 4 weeks during the vitellogenic phase of their annual reproductive cycle. The effects on total lipid and its various fractions, viz., free fatty-acids, monoglycerides, diglycerides, triglycerides, phospholipids, free cholesterol, and esterified cholesterol, were studied in the liver, plasma, gonads, and muscle. Except for elevated liver lipid in the male in response to malathion, no significant change in total lipid could be observed following pesticide exposure. However, various lipid fractions responded differently to two concentrations of the pesticides. Both pesticides affected the metabolism of nonpolar and less polar lipids alike. Malathion inhibited only mobilization of hepatic phospholipid to gonads but not its hepatic biosynthesis, whereas gamma-BHC reduced its synthesis in the liver as well. These pesticides seemed to restrict the conversion of esterified cholesterol into free cholesterol without affecting the biosynthesis of cholesterol as such. In both sexes, esterification of free fatty acids to acyl glycerides and their mobilization from liver to gonads seemed to be restricted as a result of pesticides action.

Animals↗
PubMed1989

Effects of three pesticides on MSX-induced ammonia photoproduction by the cyanobacterium Nostoc linckia.

Three pesticides (2,4-D, basalin, aldrin) inhibited L-methionine-DL-sulfoximine (MSX)-induced photoproduction of ammonia by the nitrogen-fixing cyanobacterium Nostoc linckia. Combinations of pesticides and MSX were inhibitory except at low concentrations (100 and 500 micrograms/ml) of 2,4-D which stimulated NH+4 production. Similar results were obtained when pesticides were added 6 hr after the addition of MSX, but the inhibition was weaker. When MSX was added to the culture 6 hr after the addition of pesticides, the pesticides stimulated NH+4 photoproduction. Similar results were obtained on nitrogenase activity of the organism.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1994

Cytogenetic effects on human lymphocytes of a mixture of fifteen pesticides commonly used in Italy.

Lymphocytes obtained from 5 healthy donors were incubated with a mixture of 15 pesticides commonly found in foods of central Italy (dithiocarbamates (20.7%), benomyl (19.6%), thiabendazole (14.9%), diphenylamine (14.4%), chlorthalonil (13.1%), procymidone (8.0%), methidathion (2.3%), chlorpyrifos-ethyl (2%), fenarimol (1.9%), parathion-methyl (1%), chlorpropham, parathion, vinchlozolin, chlorfenvinphos and pirimiphos-ethyl (< 1%)). The percent of each pesticide in the mixture was proportional to its average concentration in foods. Incubated with the lymphocytes at a concentration of 1-20 micrograms/ml the pesticide mixture did not induce significant variations in the number of hypodiploid, hyperdiploid and polyploid cells or in the number of chromosome and chromatid aberrations. On the contrary, we observed a dose-dependent increase in the number of nonsynchronous centromeric separations which reached the level of 37.9% at 20 micrograms/ml of pesticide mixture in the incubation medium. This effect was not observed when benomyl was excluded from the mixture. These data show that the removal of benomyl could decrease the toxicity of pesticide residues present in human food.

Adult↗
PubMed1984

Evaluation of pesticides which pose carcinogenicity potential in animal testing. II. Consideration of human exposure conditions for regulatory decision making.

In reaching a regulatory decision on the use of pesticides with carcinogenic potential, it is of great importance to investigate the extent of dermal exposure and absorption of a pesticide to users and field workers. By applying this information, along with the appropriate carcinogenicity categorization of a pesticide, a reasonably sound regulatory decision can be derived. Seven pesticides were selected, based on adequacy of tumor data, and were taken through the tumor evaluation system as reported in Part I 1984, Regul. Toxicol. Pharmacol. 4, 355-360). A step-by-step analysis on how a regulatory decision is reached on each pesticide by the EPA and CDFA was discussed.

Agricultural Workers' Diseases↗
PubMed1992

Pesticide tolerances and their relevance as safety standards.

Following an investigation of the relationship between pesticide tolerances and safety, it is concluded that pesticide tolerances are not relevant as safety standards. This conclusion is based upon the findings that theoretical exposures to legal levels of pesticides in the diet may pose greater than negligible risks, while exposures to most illegal residues are of no apparent toxicological significance. Thus, the common and logical views that "legal" residues are "safe" while "illegal" residues are "unsafe" are not supported by scientific evidence. Pesticide tolerances do serve important roles as enforcement tools, and tolerance enforcement programs are useful in the regulation of international trade and provide economic disincentives that may discourage pesticide misuse and emphasize compliance with regulations. Since tolerances are not appropriate as safety standards, however, legislative food safety proposals focusing upon revocation or reduction of tolerances and upon increasing enforcement capabilities may result in little benefit to public health.

Humans↗
PubMed1992

Toxicological considerations for protein components of biological pesticide products.

The toxicity of protein components of microbial pesticide products is evaluated at EPA by requiring that pesticide manufacturers conduct a thorough taxonomic evaluation of the active microbial ingredient. The requirement for acute toxicity testing by dosing laboratory animals with the active microbial ingredient and with fermentation growth medium materials provides additional information on the toxicity of protein components of microbial pesticides. The potential for toxicity from proteins associated with contaminating organisms is addressed by use of appropriate quality control procedures to minimize or prevent growth of contaminants and by screening of fermentation batches for known human/mammalian pathogens. These considerations also would apply to any biochemical pesticide that is formed via the growth of a microorganism. If a protein itself is intended for commercial use as an active pesticide ingredient, acute exposure studies and in vitro digestibility studies could be done to answer potential concerns regarding toxicity.

Animals↗
PubMed1995

Cytogenetic toxicity and no-effect limit dose of pesticides.

The no-effect limit dose (NELD) of three commonly used pesticides with respect to their cytogenetic toxicity was determined in a number of test systems using a sufficient number of lower doses to characterize the dose-effect relationship. For lindane, malathion and metacid, this dose was 3.2, 7.0 and 3.0 mg/litre, respectively, for mitosis inhibition and 9.0, 55 and 60 mg/litre, respectively, for chromosome clastogeny in onion root-tip cells. For chromosome clastogeny in mice bone marrow cells, the NELDs of the three pesticides were 1.6, 1.5 and 2.0 mg/kg body weight/day, respectively. These values for dominant lethals and X-chromosome-linked recessive lethals in Drosophila were 20 and 5 micrograms lindane/litre, 2 and 3.5 micrograms malathion/litre and 4 and 5.5 micrograms metacid/litre, respectively. Thus, the NELDs are not only pesticide specific but also organism specific, tissue specific and even damage specific. Furthermore, the NELD values determined are so small that the real human exposure to pesticides cannot be reduced below these levels without compromising the effectiveness of pesticides in use.

Allium↗
PubMed1995

Lack of carcinogenicity of pesticide mixtures administered in the diet at acceptable daily intake (ADI) dose levels in rats.

Carcinogenic effects of pesticide mixtures were examined with our medium-term carcinogenesis protocols using male F344 rats. In the 8-week liver model, combined dietary administration of 20 pesticides (19 organophosphorus compounds and 1 organochlorine), each at acceptable daily intake (ADI) levels, did not enhance rat liver preneoplastic lesion development initiated by diethylnitrosamine. In contrast, a mixture of 100 times ADI significantly increased the number and area of liver lesions. In the second experiment using a multi-organ carcinogenicity protocol of 28 weeks, mixtures of 40 pesticides (high volume compounds) and 20 pesticides (suspected carcinogens) added to the diet at their respective ADI levels did not enhance carcinogenesis in any organ initiated by 5 different known carcinogens in combination. These results provide support for the safety factor (usually 100) approach presently used for the quantitative hazard evaluation of pesticides.

Animals↗
PubMed1996

Childhood leukaemia and exposure to pesticides: results of a case-control study in northern Germany.

The association between childhood leukaemia and exposure to pesticides was examined in a population-based case-control study conducted in Lower Saxony, Northern Germany. Between July 1988 and June 1992, 219 newly diagnosed cases were identified, of whom 173 participated in the study. Two sex- and age-matched control groups were recruited: local controls from the same communities as the newly diagnosed cases of leukaemia and state controls from other randomly selected communities in Lower Saxony. An additional study group consisted of 175 cases of solid tumours. When the leukaemia cases were compared with the local controls, positive associations with parental occupational exposure, particularly agriculture-related exposure, were observed, which were statistically non-significant. A significant association was found for pesticide use in gardens (odds ratio = 2.52, 95% confidence interval: 1.0-6.1). No positive associations were seen when the leukaemia cases were compared to the state controls, but this finding could be explained by a higher proportion of state controls living in rural areas. In communities with a significantly elevated standardised incidence ratio of childhood leukaemia over the last decade (1984-1993), the prevalence of pesticide use in the garden was 21%, compared with the 10% in other communities. None of the examined risk factors were more common among cases of solid tumours. Our findings add some evidence to the hypothesis that pesticides are a risk factor for childhood leukaemia, and there are good reasons to consider abundant pesticide use in rural areas as a possible cause for clustering of childhood leukaemia.

Adolescent↗
PubMed1993

In vitro study of pesticide hematotoxicity in human and rat progenitors.

Some pesticides are hematotoxic and cause aplastic anemia, agranulocytosis, neutropenia, and thrombopenia. In order to evaluate hematopoietic progenitor cultures in the exploration of pesticide hematotoxicity, human and rat colony-forming unit-granulocyte and macrophage (CFU-GM) were cultured in the presence of different concentrations of pesticides, known to be either hematotoxic or innocuous for blood cells. The results were compared to the control culture of the same sample. Four insecticides (lindane, azinphos, mevinphos, parathion methyl), three herbicides, (2,4,5, T, bromacil, MCPA), and two fungicides (fosethyl-aluminum, DNOC) were tested and exhibited the following data: 1) Pesticides, known to be hematotoxic, inhibited the development of progenitors. Different phenomena were observed and suggested different mechanisms: cell destruction, block in mitosis, decrease or delay in mitosis. 2) Difference in sensitivity to molecules between human and rat progenitors was observed. Human progenitors were more sensitive to pesticides, except for 2,4,5 T.

Animals↗
PubMed2004

Effects of agricultural pesticides on the immune system of Xenopus laevis and Rana pipiens.

Over the last 30 years, there have been mass declines in diverse geographic locations among amphibian populations. Multiple causes have been suggested to explain this decline. Among these, environmental pollution is gaining attention. Indeed, some chemicals of environmental concern are known to alter the immune system. Given that amphibians are frequently exposed to agricultural pesticides, it is possible that these pollutants alter their immune system and render them more susceptible to different pathogens. In this study, we exposed two frog species, Xenopus laevis and Rana pipiens, for a short period of time to a mixture of pesticides (atrazine, metribuzine, endosulfan, lindane, aldicarb and dieldrin) representative in terms of composition and concentrations to what it is found in the environment of the southwest region of the province of Quebec. The pesticides were known to be present in surface water of many tributaries of the St. Lawrence River (Quebec, Canada). Our results demonstrate that the mixture of pesticides could alter the cellularity and phagocytic activity of X. laevis and the lymphocyte proliferation of R. pipiens. Taken together, these results indicate that agricultural pesticides can alter some aspects of the immune response in frogs and could contribute to their global decline by rendering them more susceptible to certain infections.

Analysis of Variance↗
PubMed2004

Semi disposable reactor biosensors for detecting carbamate pesticides in water.

Two flow-injection biosensor systems using semi disposable enzyme reactor have been developed to determine carbamate pesticides in water samples. Acetylcholinesterase was immobilized on silica gel by covalent binding. pH and conductivity electrodes were used to detect the ionic change of the sample solution due to hydrolysis of acetylcholine. Carbamate pesticides inhibited acetylcholinesterase and the decrease in the enzyme activity was used to determine these pesticides. Parameters influencing the performance of the systems were optimized to be used in the inhibition procedure. Carbofuran and carbaryl were used to test these systems. Detection limits for the potentiometric and conductimetric systems were both at 10% inhibition corresponding to 0.02 and 0.3 ppm of carbofuran and carbaryl, respectively. Both systems also provided the same linear ranges, 0.02-8.0 ppm for carbofuran, and 0.3-10 ppm for carbaryl. The analysis of pesticides was done a few times before the reactor was disposed. Percentages of inhibition obtained from different reactors were reproducible, therefore, no recalibration was necessary when changing the reactor. The biosensors were used to analyze carbaryl in water samples from six wells in a vegetable growing area. Both systems could detect the presence of carbaryl in the samples and provided good recoveries of the added carbaryl, i.e., 80-106% for the potentiometric system and 75-105% for the conductimetric system. The presence of carbaryl in water samples analyzed by the biosensors was confirmed by gas chromatography-mass spectrometric system. These biosensors do not require any sample preconcentration and are suitable for detecting pesticides in real water samples.

Acetylcholinesterase↗
PubMed2006

Pesticide exposure on southwestern Taiwanese with MnSOD and NQO1 polymorphisms is associated with increased risk of Parkinson's disease.

BACKGROUND: Hypothetic mechanism of the individual vulnerability to oxidative stress through metabolism of environmental xenobiotics and genotypic polymorphisms has been considered to promote the development of Parkinson's disease (PD). In this case-control study, we determined the role of manganese-containing superoxide dismutase (MnSOD) and NAD(P)H: quinone oxidoreductase 1 (NQO1) genes in PD risk in a population with high prevalence of pesticide exposure. METHODS: From southwestern region of Taiwan, we enrolled 153 patients with idiopathic PD and 155 healthy control subjects matched for age, sex and origin. Detailed questionnaires of face-to-face interviews among these subjects were collected. PCR-based restriction fragment length polymorphism (RFLP) assays were used to determine the genotypes of MnSOD (-9 T>C) and NQO1 (609 C>T) genes. RESULTS: Exposure to pesticides associated with PD was significant among patients with an increased odds ratio (OR) of 1.69 (95%CI, 1.07-2.65), and this association remained significant after adjustment for age, sex, and cigarette smoking (aOR=1.68, 95%CI, 1.03-2.76, P=0.023). Considering genetic factors, there were no significant differences in frequencies of both genotypes of MnSOD and NQO1 polymorphisms between PD patients and the control subjects (P>0.05). However, this difference in genotype distribution was significant among subjects who had been exposed to pesticide, with aOR of 2.49 (95%CI, 1.18-5.26, P=0.0072) for MnSOD C allele and aOR of 2.42 (95%CI, 1.16-4.76, P=0.0089) for NQO1 T allele, respectively. Moreover, among subjects exposed to pesticide, the combined MnSOD/NQO1 variant genotype was significantly associated with a 4.09-fold increased risk of PD (95%CI, 1.34-10.64, P=0.0052). CONCLUSION: Susceptible variants of MnSOD and NQO1 genes may interact with occupational pesticide exposure to increase PD risk in southwestern Taiwanese.

Aged↗
PubMed2005

Pesticide-induced alteration in mice hepato-oxidative status and protective effects of black tea extract.

BACKGROUND: This study investigates the role of black tea extract in protection against oxidative damage induced in mice by a subacute oral dose of a combination of pesticides. METHODS: Liver damage markers like amino-acid transferases and alkaline phosphatase, oxidative damage markers indicating extent of lipid peroxidation, host antioxidant reserve indicators like reduced glutathione (GSH) and total thiol levels, GSH-dependent enzyme activities viz., glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) superoxide dismutase (SOD) and catalase (CAT) were measured by spectrophotometric techniques in four different groups namely (1) control, (2) black tea extract, (3) pesticide alone and (4) pretreatment with black tea extract followed by pesticide treatment. RESULTS: Following exposure to pesticides lipid peroxidation was increased compared to that in the control [0.50+/-0.083 (mean+/-S.E.) vs. 0.21+/-0.02 micromol/mg protein, p<0.001]. Moreover, levels of antioxidants like GSH and total thiol were also significantly decreased in comparison to control, e.g., GSH [5.16+/-0.78 vs. 6.96+/-1.35 micromol/mg protein, p<0.001], total thiol [19.3+/-2.74 vs. 26.15+/-2.8 micromol/mg protein, p<0.001]. In addition, the activities of antioxidant enzymes like GPx, GST, GR, SOD and catalase were also likewise diminished by oxidant damage. Treatment with aqueous black tea extract significantly protects the liver tissue from the oxidative damage and shifts the trend towards amelioration and replenishment of the antioxidant status. CONCLUSIONS: The active components present in natural extracts like that of black tea can be very effective in perhaps reducing the extent of injury and in overcoming oxidant damage caused by exposure to environmental agents like pesticides.

Administration, Oral↗
PubMed2005

Degradation of some biorecalcitrant pesticides by homogeneous and heterogeneous photocatalytic ozonation.

Photo-Fenton/ozone (PhFO) and TiO2-photocatalysis/ozone (PhCO) coupled systems are used as advanced oxidation processes for the degradation of the following biorecalcitrant pesticides: alachlor, atrazine, chlorfenvinfos, diuron, isoproturon and pentachlorophenol. These organic compounds are considered Priority Hazardous Substances by the Water Framework Directive of the European Commission. The degradation process of the different pesticides, that occurs through oxidation of the organic molecules by means of their reaction with generated OH radical, follows a first and zero-order kinetics, when PhFO and PhCO are applied, respectively. These two Advanced Oxidation Processes, together with the traditional ozone+UV, have been used to investigate TOC reduction of the different pesticide aqueous solutions. The best results of pesticide mineralization are obtained when PhFO is applied; with the use of this advanced oxidation process the aqueous pesticide solutions become detoxyfied except in the case of atrazine and alachlor aqueous solutions for which no detoxification is achieved at the experimental conditions used in the work, at least after 2 and 3 h of treatment, respectively.

Coloring Agents↗