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At least 19 recordsLinked to original sources
PubMed1992

Hepatotoxicity of trichlorfon and dichlorvos in isolated rat hepatocytes.

Hepatotoxicity of organophosphorus insecticides, trichlorofon and dichlorvos, a dechlorinated form of the former, was examined in isolated hepatocytes from untreated control and phenobarbital-pretreated (80 mg/kg, i.p., for 3 days) rats. These compounds produced toxic effects on hepatocytes as evidenced by malondialdehyde production and lactate dehydrogenase leakage in a dose-dependent manner up to the concentration of 2 mM, dichlorvos being more toxic than trichlorfon. Hepatocytes from phenobarbital-pretreated rats were more sensitive to these organophosphates than those from control rats. Dichloroacetaldehyde and dichloroacetic acid, metabolites of dichlorvos, did not injure hepatocytes. The toxic effects of dichlorvos on hepatocytes were enhanced by increasing oxygen concentration during the incubation, or by addition of glycolytic substrates (pyruvate, lactate or fructose) to the incubation mixtures. On the other hand, addition of antioxidants (diethyldithiocarbamate or N,N'-diphenyl-p-phenylenediamine), or cytochrome P-450 inhibitors (SKF-525A or metyrapone) to the incubation mixtures attenuated malondialdehyde production caused by dichlorvos and protected cells from death. Addition of dichlorvos to the incubation mixtures of hepatic microsomes stimulated lipid peroxidation in the presence of NADPH, which was inhibited by further addition of superoxide dismutase but not catalase. These results suggest that hepatotoxicity of trichlorfon and dichlorvos are related to their peroxidative property in microsomes which is accelerated by oxygen.

Animals↗
PubMed1979

The chemical and biochemical reactivity of dichlorvos.

The chemical structure, reactivity and metabolic fate of the insecticide dichlorvos (2,2-dichlorovinyl dimethyl phosphate) are discussed in relation to the possible genotoxicity of this and other methyl phosphate triesters. Recent attempts to demonstrate the methylation of DNA following exposure of bacteria and animals to dichlorvos are reviewed. On the basis of comparative data relating mutagenesis to methylation reactions, it seems entirely appropriate to conclude that the mutagenicity of dichlorvos to bacteria is due solely to methylation of the bacterial DNA under the conditions of these tests. However, the methylation of mammalian DNA could not be demonstrated under realistic exposure conditions (when the alkylating mutagen methyl methanesulphonate afforded clearly measurable methylation). The failure to detect methylation by dichlorvos in vivo is attributed to the operation of highly efficient enzyme-catalysed biotransformations which rely largely on the phosphorylating reactivity of dichlorvos. The biotransformation pathways, characterised mostly in the rat, appear to be common also to pig, mouse, hamster, and man.

Animals↗
PubMed1978

Mutagenicity of dichlorvos and other structurally related pesticides in Salmonella and Streptomyces.

The following pesticides: azinphosmethyl, diallate, dichlorvos, EPTC, fenchlorphos, mevinphos, monocrotophos, noruron, parathionmethyl, triallate, trichlorphon and vegadex were tested for the ability to induce his+ revertants in four histidines requiring strains of Salmonella typhimurium--TAI 535(missense), TAI 536, TAI 537 and TAI 538 (frame-shift)- and resistance to low levels of streptomycin in Streptomyces coelicolor. Dichlorvos, which is a phosphoric ester with a dichlorovinyl group as side chain, and trichlorphon, which is known for its spontaneous conversion in dichlorvos, are both mutagenic in Salmonella (strain TAI535) and Streptomyces. Five organophosphorus pesticides similar to dichlorvos but devoid of the vinyl group are not mutagenic. Three carbamates, diallate, triallate and vegadex, which contain a chloroallyl group similar to the vinyl group of dichlorvos are mutagenic in Streptomyes; triallate and vegadex are powerful mutagens also in Salmonella (strain TAI535); two other carbamates devoid of the chlorinated group are not mutagenic. The results suggest that the presence of a vinyl chloride or allyl chloride group in the molecule of these pesticides is responsible for the ability to induce point mutations in Salmonella and Streptomyces.

Animals↗
PubMed1992

Neurotoxicity of dichlorvos: effect on antioxidant defense system in the rat central nervous system.

The effect of dichlorvos exposure (5 mg kg-1 body wt, ip) on lipid peroxidation and antioxidant defense system in different regions of the rat central nervous system was studied. In the present paper an inhibition of acetylcholinesterase activity was used as an index of dichlorvos neurotoxicity. We observed significant increases in the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase which were accompanied by a decrease in the values of lipid peroxidation. Dichlorvos exposure also resulted in a significant decrease in glutathione peroxidase activity. The decreased levels of both reduced and oxidized glutathione as observed on dichlorvos exposure affected the GSH/GSSG ratio. These results indicate that the enzymes SOD and catalase may enhance the disposal of potentially toxic radicals. Furthermore, the decrease in GSH levels may be a mechanism for the detoxification of dichlorvos in the brain.

Acetylcholinesterase↗
PubMed1978

Activities of dichlorvos or disophenol against the hookworm (Uncinaria lucasi) and sucking lice of northern fur seal pups (Callorhinus ursinus) on St. Paul Island, Alaska.

One controlled and six critical tests were conducted in July, 1977 with northern fur seal pups (Callorhinus ursinus) to determine the efficacies of a single dose of dichlorvos capsules at 29.3 to 32.8 mg/kg, tablets at 10.5 to 11.5 mg/kg, or disophenol at 9.9 mg/kg given subcutaneously against natural infections of adult Uncinaria lucasi. In the controlled test, 20 pups were treated and 10 pups were nontreated. Removal of hookworms in this test was 99% for five pups receiving dichlorvos capsules, 99% for five pups receiving dichlorvos tablets, and 77% for 10 pups receiving disophenol. Also, both formulations of dichlorvos and the formulation of disophenol were highly active against natural infestations of two species of sucking lice (Proechinophthirus fluctus and Antarctopthirus callorhini). In critical tests with four pups treated with dichlorvos capsules at 28.6 to 30.6 mg/kg, removal of hookworms was uniformly 100%. Disophenol at 9.9 mg/kg removed 100% and less than 1% of hookworms in two pups, respectively, in critical tests.

Alaska↗
PubMed1979

Teratogenic potential of dichlorvos given by inhalation and gavage to mice and rabbits.

Dichlorvos (2,2-dichlorovinyl dimethyl phosphate) is an important organophosphate insecticide and anthelmintic with widespread use. The purpose of this study was to evaluate the teratogenic potential of dichlorvos given orally at the maximum tolerated dose to mice (60 mg/kg/day) and rabbits (5 mg/kg/day) and by inhalation in both species at a concentration of 4 microgram/l seven hours daily. Dichlorvos was not found to be teratogenic in either species by either route of administration.

Administration, Oral↗
PubMed1976

Dichlorvos -- a 2-year inhalation carcinogenesis study in rats.

To determine the effects of dichlorvos vapour on the tumour incidence in rats, 5 week old Carworth Farm E strain rats weighing between 94 and 150 g were exposed to 0, 0.05, 0.5 and 5.0 mg/m3 in a 2-year inhalation study. The growth rate of all treated rats was depressed, particularly in the males. There was increased survival of the rats exposed to 5 mg/m3. There were no consistent differences in food intakes, organ weights, haematological or blood chemistry estimations, except in cholinesterase activites, amongst the various groups of rats. No compound-related differences were seen in acetylcholine and choline estimations carried out on a small number of female rats' brain tissues after two years' exposure. There were no gross or microscopical compound-related changes in the rats' tissues. Ultrastructural examination of the respiratory tissues of the rats from the control and 5 mg/m3 group showed no changes attributable to dichlorvos. The results of a relative risk analysis of the tumour data showed that no dose-related increase in tumour risk was established for rats of either sex. These data confirm the results of earlier st.udies supporting the safety of insecticidal uses of dichlorvos.

Animals↗
PubMed1977

In vivo alkylation studies with dichlorvos at practical use concentrations.

Twenty male CFE rats were exposed to atmospheres containing 0.064 microgram/l of [Me-14C] dichlorvos (113 Ci/mol) for 12 h. Analysis of the DNA and RNA from the total soft tissues of these rats revealed no methylation of the N7 atom of guanine moieties. The limits of detection of methylation were one methyl group per 6.0 X 10(11) and per 2 X 10(9) nucleotide units for DNA and RNA, respectively. Only 0.000001% of the administered dose would have needed to react with DNA in order to produce detectable methylation of this macromolecule. The exposure period employed in this study (12 h) constituted a significant fraction of the half-life of 7-methylguanine moieties in DNA (3 days). On the basis of this information and the extremely rapid metabolism of dichlorvos in a wide range of mammalian tissues and species it was concluded that dichlorvos does not methylate the nucleic acids of mammalian tissues when it is inhaled continuously at practical use concentrations.

Alkylating Agents↗
PubMed1977

Some toxicity aspects of dichlorvos flea collars in cats.

The effects of the application of a single dichlorvos flea collar containing 500 mg of the insecticide were observed in 23 growing cats for periods of from 1 to 15 weeks. No overt signs of toxicity occurred and weight gain in young growing animals was not significantly affected. Whole blood cholinesterase was reduced within the first week of application of the collar and remained below pretreatment levels for 5 to 8 weeks before returning to normal presumably as the insecticide concentration in the resin was progressively reduced. Signs of systemic organophosphate toxicity did occur within 1 week of the application of three collars to each of two cats kept in the same cage. This suggested that the likelihood of toxicity occurring in cats following the use of dichlorvos flea collars depended mainly on the degree of exposure to the insecticide. Considering recent reports in the literature it was proposed that the environmental conditions of temperature (11 degrees to 23 degrees C) and relative humidity (50 to 65%) under which the experiments were carried out would have promoted a relatively low atmospheric concentration of dichlorvos in the near environment of the test animals and hence generally prevented occurrence of clinical signs. Under most conditions of keeping domestic cats in Australia the use of a single dischlorvos flea collar should therefore be without any untoward effect although some initial and transient inhibition of whole blood and nervous tissue cholinesterases would be expected.

Animals↗
PubMed1978

Comparative efficacy of fenbendazole, dichlorvos, and levamisole HCI against gastrointestinal nematodes of pigs.

Forty-two weanling pigs raised under similar management conditions were used to compare the effectiveness of fenbendazole, dichlorvos, and levamisole HCl against Oesophagostomum dentatum, O. quadrispinulatum, Ascaris suum, Trichuris suis, Hyostrongylus rubidus, and Strongyloides ransomi. All three drugs were given in the feed. Eleven pigs served as unmedicated controls; 11 pigs received fenbendazole (3 mg/kg) on days 1, 2, and 3; 10 pigs received dichlorvos (17 mg/kg) on day 3; and 10 pigs received levamisole HCl (8 mg/kg) on day 3. Fecal specimens from all 11 pigs were collected before and after anthelmintic treatment and examined for nematode eggs. All pigs were killed on day 7, and residual nematodes were counted. The calculated efficacies against the above species, respectively, were: fenbendazole, 99.9, 100, 92.4, 66.0, 99.9, and 0%; dichlorvos, 99.4, 99.9, 100, 99.9, 99.9, and 86.9%; levamisole HCl, 97.1, 99.7, 97.9, 26.1, 94.4, and 99.9%.

Animals↗
PubMed1975

Partition of an organophosphorus compound, dichlorvos, between liquid and liquid crystalline phases.

The partition coefficients for an organophosphorus compound, dichlorvos (2,2-dichlorovinyl dimethyl phosphate), between pure liquids, micellar solutions, and liquid crystalline phases were determined by spectrometric analysis of the dichlorvos content after equilibration and separation of the phases. The results demonstrated the pronounced importance of associated colloid structures on the partition coefficient and showed that the partition coefficient did not display a simple concentration dependence.

Chemistry, Pharmaceutical↗
PubMed1975

Efficacy of two dichlorvos formulations against larval and adult Hyostrongylus rubidus in swine.

Coated (V-13) and uncoated (V-22) formulations of dichlorvos were used to treat experimentally established Hyostrongylus rubidus infections of pigs at intervals after exposure to infective larvae. Both dichlorvos formulations were efficacious against the adult stomach worm H rubidus, but showed little or no activity against 5- or 15-day-old worms. Neither formulation was as effective against H rubidus in sows as in barrows and gilts.

Administration, Oral↗
PubMed1992

Erythro-toxicity of dichlorvos and possibility of its modification in vitro.

The purpose of this study was to investigate the in vitro effects of dichlorvos (organophosphorous pesticide) on the biological value of erythrocytes; an in vitro test of erythrocyte protection against DDVP effects was also included. A significant decrease of glutathione level with concomitant increase of methemoglobin and denatured hemoglobin levels, as well as a rise of Heinz body number were observed after 24 h following the treatment with dichlorvos (100 microM). Preincubation of erythrocytes with glutathione prevented the toxic effects of the pesticide with the maintenance of both glutathione and methemoglobin at a control level.

Cells, Cultured↗
PubMed1977

Management program for improving sow and gilt performance by feeding dichlorvos.

Treated sows were on a special management program which consisted of feeding 1,000 mg of dichlorvos to the sow each day for the last 30 days of gestation. The dichlorvos was delivered as a slow-release formulation. The late gestation treatment signigicantly (P less than 0.01) improved the productivity of the sows by improving the performance of their litters. The litters from treated sows were superior in 4 ways: (1) increased number of pigs born alive per litter (2.3%); (2) increased pig birth weights (9.6%); (3) improved survival of pigs born alive; and (4) improved growth rate to market weight. The litters from treated sows were 11.6%, 16.5%, and 12.4% heavier than control litters at birth, weaning (35 days), and market (160 days), respectively.

Administration, Oral↗
PubMed1979

[Use of dichlorvos in flour mills].

In the framework of studies on the possible use of dichlorvos (DDVP) in flour mills, the authors investigated the effects of various parameters (such as concentration of the DDVP solution to be used, temperature, location of the samples, different kinds of samples and packages) on the formation of DDVP residues on milling products. It was found that a concentration of 0.6 ml of DDVP-50/m3 and temperatures ranging from 18 degrees to 22 degrees C are particularly suited for insect control. Under these conditions, the DDVP residues on the samples were degraded within a period of 2--4 weeks, according to the kind of product. Uncovered foods shall not be present in rooms where DDVP is being applied. In virtue of the present findings, DDVP is recommended for use in flour mills.

Dichlorvos↗
PubMed1979

Effects of dichlorvos (DDVP) inhalation on the activity of acetylcholinesterase in the bronchial tissue of rats.

The experiments presented here deal with the effects of the inhalation of dichlorvos [dimethyl-(2,2 dichlorvinyl)-phosphate, DDVP] vapor on acetylcholinesterase (ACHE) activity in rat bronchial tissue. Exposure to DDVP concentrations of 0.8 and 1.8 micrograms/l for 3 days reduced ACHE activity in the bronchial tissue (62.8 +/- 0.8 and 51.6 +/- 1.6% of the control), but did not elicit any changes in blood ACHE activity (101 +/- 4.5% of the control each). Higher concentrations (4.3 micrograms/l) induced a decline in ACHE activity also in the blood (38.2 +/- 1.1% of the control). In the histochemical preparations used to demonstrate ACHE activity in bronchial tissue (thiolacetic acid method), a staining of the bronchial glands and smooth muscles characteristic of the enzyme activity was strongly reduced after exposure of the animals to even the lowest dose applied (0.2 microgram/l). The question of whether localized inhibition of ACHE in the bronchial tissue might cause increases in airway resistance due to activation of a broncho-bronchial reflex is discussed. This efferent cholinergic mechanism has been found to be at least partly responsible for maintenance of bronchospasm and hypersecretion in chronic obstructive diseases of the respiratory system.

Acetylcholinesterase↗
PubMed1992

High-performance liquid chromatographic method using ultraviolet detection for measuring metrifonate and dichlorvos levels in human plasma.

We report high-performance liquid chromatographic methods using ultraviolet detection, developed for the first time in our laboratory with sensitivity to detect clinically significant concentrations of metrifonate (MTF), an experimental drug for Alzheimer disease, and its active anticholinesterase metabolite, dichlorvos (DDVP). The determination limit of the method for MTF and DDVP was 1 microgram/ml and 40 ng/ml, respectively. Stability of MTF and DDVP at various temperatures in water, buffered solutions and in human plasma were also studied.

Chromatography, High Pressure Liquid↗