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PubMedDate not supplied

Accumulation pattern of pesticides in tropical fresh waters.

High-performance liquid chromatography has been used to study the persistence of commonly used organophosphorus and carbamate pesticides-carbaryl, carbendazim, carbofuran, dimethoate, malathion and methyl parathion in river water in the presence of bottom sediment in laboratory aquaria. The fate of pesticides in water and sediment in pre- and post-monsoon water from three sources has been compared. It has been established that rapid degradation occurs once the pesticide leaches into sediment from water. Degradation was at a much faster rate in post-monsoon water and sediment. It was found that pH and organic matter content affect rate of decay.

Antinematodal Agents↗
PubMedDate not supplied

Simultaneous determination of a mixture of organophosphorus and carbamate pesticides by high performance liquid chromatography.

A simple HPLC procedure has been developed for the simultaneous determination of a mixture of standard carbaryl, carbofuran, carbendazim, dimethoate, malathion and methyl parathion from a spiked agricultural soil sample. The pesticide mixture has been extracted using methanol-water. A concave gradient elution with acetonitrile-phosphate buffer for 15 min followed by linear elution for 5 min, using a wavelength of 224 nm for detection, has been found to resolve the mixture efficiently.

Benzimidazoles↗
PubMed1997

Heat shock proteins (HSP70) as biomarkers in ecotoxicological studies.

Hsp70, so-called stress proteins, were studied in the centipede Lithobius mutabilis when exposed in laboratory tests to different concentrations of the insecticide dimethoate (DMT; 0, 0.012, 0.111 mg kg-1 dwt), the detergent linear alkilobenzene sulfonate (LAS; 0, 16, 80, 400, 2000, 10,000 mg kg-1 dwt), and copper (Cu; 0, 56, 167, 500, 1000, 1500 mg kg-1 dwt) and in the field in captured animals from polluted (2 and 4 km from a zinc-and-lead smelter) and unpolluted (35 and 40 km from the smelter) areas. Hsp70 in centipedes were also tested for seasonal differences (March and September) in field-captured animals and for a temperature effect under laboratory conditions (5, 15, and 25 degrees C). Moreover, hsp70 were examined in housefly (Musca domestica) pupae after rearing larvae on food medium contaminated with DMT or LAS. Hsp70 were found in all animals tested, including controls, and their levels were not clearly related to the laboratory treatment with chemicals or temperature or to the degree of contamination in polluted areas. In centipedes from unpolluted areas, a significant seasonal difference in hsp70 content was found. The problems with using hsp70 as a universal biomarker in ecotoxicological studies are discussed.

Animals↗
PubMed2000

Simultaneous geno- and immunotoxicological investigations for early detection of organophosphate toxicity in rats.

Detectability of toxic effects by repeated doses of dimethoate (DM) and methylparathion (MPT) were investigated by geno-and immunotoxicological methods in male Wistar rats following a 28-day oral exposure. In the dose range of 28.2, 14.1, and 7.04, and 7.04 mg/kg/day DM, the two higher doses decreased the body weight gain. The top dose increased the weight of liver, kidneys, and testicles; the white blood cell count; and the cell content of the femoral bone marrow. From immune function parameters measured [IgM-plaque forming cells (PFC) assay, delayed-type hypersensitivity (DTH) reaction] only the maximum of the DTH reaction decreased at the top dose. Of the MPT doses (0.872, 0.436, and 0.218 mg/kg/day) the two higher ones increased the liver weight, and a dose-dependent increase was found in the MCV value. No evaluable changes in the examined immune function parameters were observed. Both substances increased the number of numerical but not the structural chromosome aberrations at lower dose levels (the two larger doses of DM, and all the three doses of MPT) than those ones which caused changes in the examined immune function parameters. According to these results, the genotoxicological approach seems to be more sensitive for detection of repeated-dose oral toxicity of the investigated two organophosphates than the immunotoxicological one.

Animals↗
PubMed1986

Induction of chromosomal aberrations in the Syrian hamster by insecticides tested in vivo.

The insecticides demeton, dimetoat, dichlorovos, endosulfan, trichlorofon, carbaryl, lindane, methoxychlor, propoxur and malathion were examined for their ability to induce chromosomal aberrations in the bone marrow cells of the Syrian hamster (Mesocricetus auratus) treated in vivo. Mutagenicity of commercial preparations was examined at four doses: LD50; 1/2, 1/5 and 1/10 LD50. The positive control was an IP injection of cyclophosphamide to hamsters at a dose of 40 mg/kg body wt. Demeton, dichlorovos and endosulfan gave positive results. Malathion, dimethoate and the mixture of methoxychlor and propoxur were weakly clastogenic; at some doses these compounds induced statistically significant increases in the number of aberrations. Trichlorfon and the mixture of carbaryl and lindane were negative in this test.

Animals↗
PubMed1993

Cholinesterase reactivation in organophosphorus poisoned patients depends on the plasma concentrations of the oxime pralidoxime methylsulphate and of the organophosphate.

We measured in nine patients, poisoned by organophosphorus agents (ethyl parathion, ethyl and methyl parathion, dimethoate, or bromophos), erythrocyte and serum cholinesterase activities, and plasma concentrations of the organophosphorus agent. These patients were treated with pralidoxime methylsulphate (Contrathion), administered as a bolus injection of 4.42 mg.kg-1 followed by a continuous infusion of 2.14 mg.kg-1/h, a dose regimen calculated to obtain the presumed "therapeutic" plasma level of 4 mg.l-1, or by a multiple of this infusion rate. Oxime plasma concentrations were also measured. The organophosphorus agent was still detectable in some patients after several days or weeks. In the patients with ethyl and methyl several days or weeks. In the patients with ethyl and methyl parathion poisoning, enzyme reactivation could be obtained in some at oxime concentrations as low as 2.88 mg.l-1; in others, however, oxime concentrations as high as 14.6 mg.l-1 remained without effect. The therapeutic effect of the oxime seemed to depend on the plasma concentrations of ethyl and methyl parathion, enzyme reactivation being absent as long as these concentrations remained above 30 micrograms.l-1. The bromophos poisoning was rather mild, cholinesterases were moderately inhibited and increased under oxime therapy. The omethoate inhibited enzyme could not be reactivated.

Adult↗
PubMed1983

Influence of pretreatment with various insecticides on the N-demethylation of dimethylnitrosamine.

The effects of various classes of insecticides were studied on the N-demethylation of dimethylnitrosamine (DMN) by mouse liver enzymes. Organochlorine insecticides, represented by lindane, DDT, and endrin, increased the activities of DMN demethylase I and II. The latter enzyme was more susceptible to the inducive action of the tested chlorinated insecticides. On the other hand, the synthetic pyrethroids, fenvalerate and flucythrinate, did not alter the activity of either enzyme. While pretreatment with carbaryl, a carbamate derivative, was without effect, moderate elevation in the activity of both demethylases was observed following administration of carbofuran. Dimethoate, representing organophosphorus compounds, was the only insecticide tested to inhibit the N-demethylation of DMN, with more pronounced effect on DMN demethylase I. Since DMN requires metabolic activation for its hepatotoxic and carcinogenic actions, alterations in the activities of its metabolizing enzymes as a sequela of exposure to certain insecticides may change susceptibility to its toxicity and/or carcinogenicity.

Animals↗
PubMed1988

Genotoxicity studies with four organophosphorus insecticides using the unstable white-zeste system of Drosophila melanogaster.

The present study was carried out to evaluate the suitability of the unstable white-zeste system in Drosophila melanogaster by testing 4 organophosphorus insecticides for potential genotoxic activity: dimethoate, fenitrothion, malathion, and methyl parathion. In view of the high sensitivity to insecticides of the unstable zeste strain used in this assay and the negative results obtained in this work, the white-zeste system does not appear to be sufficiently accurate for the evaluation of the mutagenic potential of specifically toxic chemicals, like insecticides.

Animals↗
PubMed1988

Genotoxicity of Rogor studied in the sex-linked recessive lethal test and wing, eye and female germ-line mosaic assays in Drosophila melanogaster.

The genotoxic potential of Rogor (dimethoate), an anticholinesterase organophosphate insecticide, has been studied in the sex-linked recessive lethal test and the wing, eye and female germ-line mosaic assays in Drosophila melanogaster. Larvae of different instars carrying suitable recessive genetic markers on their first and third chromosomes were exposed to the LD50 or half of this dose for the entire larval life. The Basc technique was followed for the detection of the induction of sex-linked recessive lethals. The wings and eyes of the adult flies and the eggs laid by the heterozygous females were checked for the induction of mosaicism. It is concluded that Rogor induces sex-linked recessive lethals in immature male germ cells and is recombinogenic and/or mutagenic in both the somatic and the germ-line cells of Drosophila.

Animals↗
PubMed1985

Potential consequences of a fire in an insecticide storage facility.

Assumptions are identified and made in an attempt to model the acute human health risk associated with a hypothetical fire in an insecticide storage facility. The insecticides used in the model are endrin and dimethoate. The model indicates that persons residing a few hundred meters from the facility could suffer a variety of adverse effects, including possible death from contact with smoke from a prolonged, low-temperature fire. Knowledge of the special hazards of cool toxic smoke as well as current atmospheric conditions could be of use to fire fighters. That is, fire fighters might wisely choose to promote a fast, hot fire which would propel toxicants high into the atmosphere rather than risk local fumigation.

Animals↗
PubMed2004

Influence of the application of sewage sludge on the degradation of pesticides in the soil.

A study was made of the influence of the application of sewage sludge on the degradation of pesticides in the soil. Two kinds of sludge were used, with different characteristics, one from an urban treatment plant and one from a food processing plant. Three organophosphorus insecticides, fenitrothion, diazinon and dimethoate, were studied. The relative importance was determined of the chemical and biological degradation processes, which involved experiments on soil and sterile soil samples. A comparative study was also made of the degradation of pesticide residues and the evolution of the microbial population. The application of sludge seems to have a complex effect on the degradation of pesticides, determined by the bioavailability and biodegradability of their active ingredient. The biodegradation of pesticide residues brings about alterations in the microorganism population of the soil.

Biodegradation, Environmental↗
PubMed2005

Determination of pesticide residues in olives and olive oil by matrix solid-phase dispersion followed by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry.

A novel analytical approach has been developed and evaluated for the quantitative analysis of a selected group of widely used pesticides (dimethoate, simazine, atrazine, diuron, terbuthylazine, methyl-parathion, methyl-pirimiphos, endosulfan I, endosulfan II, endosulfan sulphate, cypermethrin and deltamethrin), which can be found at trace levels in olive oil and olives. The proposed methodology is based on matrix solid-phase dispersion (MSPD), (with a preliminary liquid-liquid extraction in olive oil samples) using aminopropyl as sorbent material with a clean-up performed in the elution step with Florisil, followed by mass spectrometric identification and quantitation of the selected pesticides using both gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode and liquid chromatography tandem mass spectrometry (LC-MS-MS) in positive ionization mode. The recoveries obtained (with mean values between 85 and 115% (obtained at different fortification levels) with RSD values below 10% in most cases, confirm the usefulness of the proposed methodology for the analyses of these kind of complex samples with a high fat content. Moreover, the obtained detection limits, which were below 5 microg kg(-1) by LC-MS analyses and ranged from 10 to 60 microg kg(-1) by GC-MS meet the requirements established by the olive oil pesticide regulatory programs. The method was satisfactorily applied to different olives and olive oil samples.

Dimethoate↗
PubMed2006

Phototactic behavior in Daphnia magna Straus as an indicator of toxicants in the aquatic environment.

In this study, the phototactic behavior of Daphnia magna was investigated as a possible bioindicator for the following 11 chemicals commonly found in the aquatic environment: benzo(b)fluoranthene, mercury (II) chloride, dimethoate, lindane, linuron, MCPA, TBTO, carbon tetrachloride, thiram, 2,4,6-trichlorophenol and arsenic trioxide. Phototactic response was monitored as the movement of 7 to 8 day-old D. magna individuals. The analysis was carried out using glass test tubes divided radially into two zones, with increasing distance from a light source. For each of the compounds, different concentrations and exposure times were analyzed, and the behavior of the D. magna in each of the treatments compared to the controls in which the chemicals were not added. Using the experimental model described here, all of the 11 chemicals could be detected following exposure times of between 15 min and 48 h. The lowest concentrations detected using this technique were between 2 and 43 times lower than the LC(50) and EC(50) values reported for D. magna. The results of this study show that the analysis of phototactism is a useful method for detecting the presence of a wide range of potentially toxic chemicals found in the aquatic environment.

2-Methyl-4-chlorophenoxyacetic Acid↗
PubMed2005

Extrapyramidal parkinsonism complicating acute organophosphate insecticide poisoning.

The aim of this study is to report our experience with a child who developed extrapyramidal perturbations complicating acute organophosphate insecticides poisoning and to review the literature reporting on basal ganglia impairment associated with this poisoning. Our patient had developed overt parkinsonism presenting with a resting tremor, expressionless face, and lack of blinking along with marked cogwheel rigidity and a stooped, slow gait. He was alert, coherent, and cooperative, yet agitated. The parkinsonian perturbations developed 5 days after an accidental ingestion of a raw eggplant sprayed with the organophosphate dimethoate (Rogor) when he had already recovered from the acute cholinergic crisis, the first stage of organophosphate poisoning. Such a presentation was initially perceived by his caregivers as severe reactive depression or even psychosis. Once a parkinsonian syndrome was diagnosed, he was begun on amantadine and completely recovered within 1 week with no relapse of symptoms. Basal ganglia impairment should be considered in any patient who develops extrapyramidal symptoms such as marked rigidity and bradykinesia or choreoathetosis while recovering from the acute cholinergic phase of organophosphate insecticide poisoning. Thus, administration of a drug such as amantadine, which probably enhances neurotransmission, may hasten the rate of recovery and prevent long-term neurologic and emotional sequelae.

Acute Disease↗
PubMed2001

Metabolic activation of three arylamines and two organophosphorus insecticides by coriander (Coriandrum sativum) a common edible vegetable.

Organophosphorus insecticides and arylamines, widely distributed in the environment, can be activated into mutagens by plants. Plant activation of three aromatic amines, 4-nitro-o-phenylenediamine (NOP), m-phenylenediamine (m-PDA) and 2-aminofluorene (2AF), and two organophosphorus insecticides, dimethoate and methyl parathion has been the focus of this study. The plant cell/microbe coincubation assay was used employing coriander (Coriandrum sativum) suspended cell cultures as the activating system. Interestingly, this vegetable is included in the Mexican diet and ingested generally uncooked and could have epidemiological consequences. As a genetic end point, the Salmonella typhimurium tester strain TA98 was used. Protein contents, as well as peroxidase activity and peroxidase activity inhibited by diethyldithiocarbamate (DEDTC) of coriander cultures were determined after the coculture. Coriander cells highly activated three aromatic amines, NOP, m-PDA and 2-AF to mutagenic products detected in Salmonella. On the other hand, insecticides were only lightly activated, probably because peroxidase activity of coriander cells was inhibited, corroborated by DEDTC peroxidase inhibition. In all the assays, NOP was the more potent mutagenic compound. The results demonstrated that coriander cells were metabolically competent and suitable for a plant cell microbe coincubation assay, developed to analyze the promutagen activation by plant systems and can be used as a indicator of potential genetic effects.

Biotransformation↗
PubMed1997

Human lymphocyte micronucleus genotoxicity test with mixtures of phytochemicals in environmental concentrations.

This study was carried out to assess the genotoxicity of mixtures of pesticides using the micronucleus test with human lymphocytes in culture. Benomyl, azinphos-methyl, diazinon, dimethoate, pirimiphos-methyl pesticides were tested at doses estimated from their daily intake (EDI). Benomyl is a carbamate fungicide, the other compounds are organophosphorous insecticides. The compounds were tested both separately and in combination. The results showed a weak genotoxicity for three of the four organophosphorous insecticides and for benomyl. The various mixtures did not give additive effects.

Azinphosmethyl↗
PubMed2004

Effect of different soil textures on leaching potential and degradation of pesticides in biobeds.

Biobeds can be used to intercept pesticide-contaminated runoff from the mixing/washdown area, creating optimum conditions for sorption and biodegradation such that the amount of pesticide reaching adjacent water bodies is significantly reduced. The biobed is built on the farm using locally available materials, which include, straw, compost, and topsoil. The topsoil acts as the inoculum for the system and is likely to vary in terms of its physical, chemical, and microbiological characteristics from one farm to another. This study therefore investigated the effects of using different soil types on the degradation and leaching potential from biobeds. Three contrasting topsoils were investigated. Leaching studies were performed using isoproturon, dimethoate, and mecoprop-P, which were applied at simulated disposal rates to 1.5 m deep biobeds. Annual average concentrations were similar for each soil type with leaching losses of even the most mobile (Koc = 12-25) pesticide <1.64% of the applied dose. Greater than 98% of the retained pesticides were degraded in all matrices. Degradation studies investigated the persistence of individual pesticides and pesticide mixtures in the different matrices. DT50 values for isoproturon, chlorothalonil, mecoprop-P, and metsulfuron-methyl applied at 4 times the maximum approved rate were similar across the biomix types and were all less than or equal to reported DT50 values for soil treated at approved rates. When applied as a mixture, DT50 values in each biomix increased, indicating that interactions between pesticides are possible. However, DT90 values of <167 days were obtained in all circumstances, indicating a negligible risk of accumulation. Studies therefore indicate that substrate will have little impact on biobed performance so it should be possible to use local soils in the construction process.

2-Methyl-4-chlorophenoxyacetic Acid↗