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PubMed2002

Microwave-assisted extraction (MAE)-acid hydrolysis of dithiocarbamates for trace analysis in tobacco and peaches.

A simple and rapid method is presented for the analysis of residues of ethylenebis(dithiocarbamate) (maneb, zineb, and mancozeb) and N,N-dimethyldithiocarbamate (thiram and ziram) fungicides in dry tobacco leaves and peaches. Residues are extracted and hydrolyzed to CS(2) in a single step by use of microwave energy in a closed-vessel system while the evolved CS(2) trapped in a layer of iso-octane overlaying the reaction mixture is taken for gas chromatographic-flame photometric analysis. This combined extraction-hydrolysis step is carried out in 10 and 15 min for sets of 12 samples of tobacco and peach matrices, respectively. Total sample preparation time for GC analysis is 40 min. The limits of detection (LOD) are 0.005 mg/kg for thiram and ziram on peaches and 0.1 mg/kg for maneb, zineb, and mancozeb on tobacco. The respective LOD and limit of quantification (LOQ) levels in CS(2) equivalents are 0.003 and 0.006 mg/kg on peaches and 0.04 and 0.2 mg/kg on tobacco, respectively. Recoveries in the 0.01-60 mg/kg fortification range are 80-100% with respective relative standard deviations <20%. The method was used for the analysis of >3000 commercial tobacco samples including also different marketed cigarette brands.

Drug Stability↗
PubMed1978

Oral toxicity of ferric dimethyl-dithiocarbamate (ferbam) and tetramethylthiuram disulfide (thiram) in rodents.

Single oral doses of ferbam, thiram, zineb, or maneb produced central nervous system stimulation followed by depression and alopecia. Ferbam and thiram were more toxic on the basis of weight than zineb; maneb was relatively nontoxic. There was no species difference in acute toxicity between rats and mice. In 13- and 80-wk feeding studies, the toxic effects of ferbam and thiram in rats were similar; however, thiram was more toxic on the basis of weight than ferbam. During the 80-wk feeding study, weight gain was reduced in ferbam-treated rats starting at daily doses of 8 mg/kg in males and 37 mg/kg in females and in thiram-treated rats staring at daily doses of 5 mg/kg in males and 26 mg/kg in females. Food consumption was reduced in proportion to the reduced weight gain. Death occurred in males fed 109 or 331 mg/kg.d ferbam and in males fed 58 or 132 mg/kg.d thiram. Female rats fed 96 mg/kg.d ferbam or 67 mg/kg.d thiram developed alopecia and ataxia, which led to paralysis of the hind limbs. Male rats fed ferbam or thiram had a more severe incidence of squamous metaplasia in the thyroid and fatty infiltration in the pancreas than control males. Ferbam or thiram reduced the incidence of spontaneous nephritis in both males and females. The male rats that were fed 109 or 331 mg/kg.d ferbam and died betweeen 1 and 5 wk had golden pigment in the reticuloendothelial cells of the spleen and in the enlarged mesenteric lymph nodes, associated with hemosiderosis. Moderate tubular degeneration of the testes with atypical spermatids in the epididymis occured in some rats fed 132 mg/kg.d thiram for 13 wk but not in rats fed up to 52 mg/kg.d for 80 wk. Periodic hematologic examination and terminal clinical blood tests did not reveal any severe changes. Ferbam and thiram did not alter the occurrence or latent period of the spontaneous tumors seen in control rats.

Animal Feed↗
PubMed1983

Allergic contact dermatitis from ethylene thiourea.

A case of allergic contact dermatitis to the rubber additive material ethylene thiourea (ETU) is presented. Testing for cross-sensitivity gave a positive reaction to the fungicide Maneb, manganous ethylenebisdithiocarbamate, but this reaction was probably due to ETU which was detected in Maneb by thin-layer chromatography. Different sources of ETU are reported.

Dermatitis, Contact↗
PubMed1990

Studies on synergistic toxic effects of copper and dithiocarbamate pesticides with the ciliate protozoan Colpidium campylum (Stokes).

The toxicity of seven dithiocarbamates and interactions occurring with copper were studied with the ciliate protozoan Colpidium campylum. No product was toxic at 0.1 mg liter-1. Thiram and mancozeb are the most toxic products (lethal at 1 mg liter-1) and ziram and propineb the least toxic. Concerning interactions with copper, no or slight interactions were observed with propineb and mancozeb, although a strong synergistic toxic effect was observed in a previous work with two structurally related products, maneb and zineb. On the contrary, the responses observed with alkyl-related dithiocarbamates (ferbam and ziram) and ethylene bis-related dithiocarbamates (nabam, thiram, and metiram) are in correlation with the results known in the literature. The synergistic toxic effect of copper and dithiocarbamates thus seems to be related mainly to the alkyl- or the ethylene bis-dithiocarbamate structure, but is not constant for molecules associated with metals (propineb, mancozeb, maneb, and zineb).

Animals↗
PubMed2004

Proteasomal inhibition induced by manganese ethylene-bis-dithiocarbamate: relevance to Parkinson's disease.

Maneb, a widely used fungicide, has been associated with Parkinsonism in humans. In experimental models, maneb and its major active element, manganese ethylene-bis-dithiocarbamate (Mn-EBDC) cause selective nigrostriatal neurodegeneration in mice and in rats, respectively. To investigate the mechanisms underlying this neurodegeneration, we studied the effects of Mn-EBDC on proteasomal function, which is decreased in patients with Parkinson's disease (PD), in a dopaminergic neuronal cell line (MES 23.5 or MES). The results demonstrated that exposure of MES cells to 6 microM Mn-EBDC for 7 days produced not only significant neurotoxicity but also inhibition of proteasomal chymotrypsin-like and postglutamyl peptidase activities. Proteasomal dysfunction was accompanied by formation of cytoplasmic inclusions that were positive for alpha-synuclein immunostaining and significantly increased sodium dodecyl sulfate-insoluble alpha-synuclein aggregation seen by Western blot analysis. In addition, there was a significant increase in oxidative stress, evidenced by elevated total protein carbonyl content, in cells treated with Mn-EBDC. Manipulation of intracellular reduced glutathione levels with N-acetyl-L-cysteine or L-buthionine sulfoximine pretreatment to modulate Mn-EBDC-mediated oxidative stress altered Mn-EBDC-mediated neurotoxicity, proteasomal dysfunction, and alpha-synuclein aggregation in these cells. These data suggest that neurotoxicity-induced by Mn-EBDC is at least partially attributable to Mn-EBDC-mediated proteasomal inhibition, and that the proteasome may be an important target by which environmental exposure modifies the risk for developing PD in vulnerable populations.

Amino Acid Sequence↗
PubMed1987

Comparative effects of ten dithiocarbamate and thiuram compounds on tissue distribution and excretion of lead in rats.

Combined treatment of rats with lead and disulfiram is known to cause increased levels of lead in brain and potentiation of the neurotoxicity of lead. Ten dithiocarbamate and thiuram compounds, including disulfiram, were compared for their efficacies in influencing tissue distribution of a trace dose of intravenously injected lead plus 203Pb in rats. The tested compounds were sodium diethyldithiocarbamate (DEDTC), sodium dimethyldithiocarbamate (DMDTC), tetraethylthiuram disulfide (disulfiram), a complex of zinc and manganese ethylenebisdithiocarbamate (mancozeb), manganese ethylenebisdithiocarbamate (maneb), sodium monomethyldithiocarbamate (metham), zinc propylene bisdithiocarbamate (propineb), tetramethylthiuram disulfide (thiram), zinc ethylenebisdithiocarbamate (zineb), and zinc dimethyldithiocarbamate (ziram). Pronounced effects on tissue distribution of lead were seen after peroral and subcutaneous administration of DEDTC, DMDTC, disulfiram, metham, thiram, and ziram. After peroral administration there was an increased uptake of lead in brain, liver, lung, and spleen and a decreased uptake in femur compared to control rats receiving only lead. Thiram was the most effective compound in enhancing lead uptake in brain, causing a 100-fold increase in 203Pb concentration at 72 hr survival. After subcutaneous administration, metham caused the highest increase in brain concentration of 203Pb. Fecal excretion of lead, which is the main excretory pathway, was decreased after peroral administration of disulfiram, ziram, and thiram to about 20% of the excretion in control rats at 48 hr. Urinary excretion of lead was significantly decreased in all the treated groups except the group treated with zineb. The effects on tissue distribution and excretion can be explained by in vivo formation of lipophilic complexes between lead and these compounds or their metabolites facilitating the transport of lead through cell membranes and the blood-brain barrier. Zineb, maneb, propineb, and mancozeb did not cause similar effects on the tissue distribution of lead. The results of this study show that interactions can occur between lead and DEDTC, DMDTC, disulfiram, metham, thiram, and ziram, resulting in increased levels of lead in brain and probably potentiation of the neurotoxic effects of lead.

Animals↗
PubMed1978

Tests in vitro and in pots with certain chemicals for inhibition of Pseudomonas solanacearum.

Twenty one isolates of Pseudomonas solanacearum E. F. Smith (Race 3) from various parts of Egypt were inhibited in vitro by Ampicillin, Chloramphenicol, Kanamycin, Oxytetracycline. Tetracycline, Penicillin G, Streptomycin, Nabam (Dithane A-40), Maneb (Dithane M-22), Zinc-ion maneb complex (Dithane M-45), and the insecticide Chlorthion. On the basis of in vitro-sensitivity to the selected 11 chemicals the 21 isolates could not be separated into different groups. Carbendazin (Bavistin), Benomyl, Drazoxolon (Mil-Col), and Temik proved ineffective in inhibiting the in vitro growth of all isolates at all tested concentrations. Preliminary investigations indicate that drenching the soil with solutions of Dithane M-22 (0.25% w/v, Dithane M-45 (0.25%) w/v, or insecticide Chlorthion (50 microgram/ml active ingredient) decreased the incidence of potato wilt disease that developed in soil, artificially infested with P. solanacearum.

Anti-Bacterial Agents↗
PubMed2003

Manganese ethylene-bis-dithiocarbamate and selective dopaminergic neurodegeneration in rat: a link through mitochondrial dysfunction.

Manganese ethylene-bis-dithiocarbamate (Mn-EBDC) is the major active element of maneb, a pesticide linked to parkinsonism in certain individuals upon chronic exposure. Additionally, it has been shown to produce dopaminergic neurodegeneration in mice systemically coexposed to another pesticide, 1,1'-dimethyl-4,4'-bipyridinium (paraquat). Here, we described a rat model in which selective dopaminergic neurodegeneration was produced by delivering Mn-EBDC directly to the lateral ventricles. After establishing this model, we tested whether Mn-EBDC provoked dopamine efflux in the striatum, a well-known phenomenon produced by the mitochondrial inhibitor 1-methyl-4-phenylpyridinium (MPP+), the active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that causes parkinsonism in humans, as well as in some animals. Finally, we investigated whether Mn-EBDC directly inhibited mitochondrial function in vitro using isolated brain mitochondria. Our data demonstrated that Mn-EBDC induced extensive striatal dopamine efflux that was comparable with that induced by MPP+, and that Mn-EBDC preferentially inhibited mitochondrial complex III. As mitochondrial dysfunction is pivotal in the pathogenesis of Parkinson's disease (PD), our results support the proposal that exposure to pesticides such as maneb, or other naturally occurring compounds that inhibit mitochondrial function, may contribute to PD development.

Animals↗
PubMed2002

Mycorrhizal growth in pure cultures in the presence of pesticides.

The effects of pesticides on 64 ectomycorrhizal fungi of boreal forest trees were studied in vitro. The pesticides (fungicides: benomyl, chlorothalonil, copper oxychloride, maneb and propiconazole; herbicides: chlorthiamid, glyphosate, hexazinone, linuron and terbuthylazine; insecticide: cypermethrin) were selected as those commonly used in Nordic forest nurseries and afforestation sites. In general, the fungicides proved to be more toxic to ectomycorrhizal fungi than the herbicides and cypermethrin. The fungicides, chlorothalonil and propiconazole, had the clearest inhibitory effect on growth of mycorrhizal fungi. Conversely, maneb, glyphosate and terbuthylazine stimulated the growth of some mycorrhizal fungi. Leccinum versipelle and L. scabrum, Paxillus involutus and Cenococcum geophilum were the most sensitive ectomycorrhizal fungi to the various pesticides.

Colony Count, Microbial↗
PubMed1997

Dermatitis in Ecuadorean farm workers.

Using a cross-sectional survey of potato farm workers in northern Ecuador, we examined the relationship between pesticide exposure and skin disorders. From a farm population census, all pesticide applicators and 1/2 of exposed field workers were selected. Controls were age-matched from urban occupations. Individual exposure measures included overall years and current hours working with pesticides. Farm-level measures included numbers of applications over the last 6 months and an application practices score (range 0-4). Each participant underwent a clinical skin examination, with patch tests to maneb on a sample of dermatitis cases. Exposure-related increases in conjunctivitis (7% of applicators, 0% in other groups), dermatitis (68% of exposed and 55% of applicators versus 31% of controls, p < 0.001) and pigmentation disorders (25% of exposed and applicators vs 10% controls, p = 0.06) were found. Among dermatitis cases (n = 117), 5% were positive to maneb on patch testing. In logistic regression analysis, significant predictors (p < 0.1) of dermatitis included years using fungicides (OR = 1.12 per year) and poor application practices (OR = 1.42 per score unit). Agricultural fungicide application in high-exposure situations can contribute to dermatitis prevalence among farm populations.

Adult↗
PubMed1967

Laboratory examination of organic fungicides against zoopathogenic fungi in soil.

Seven commercial and five experimental organic fungicides were tested against Histoplasma capsulatum, Cryptococcus neoformans, Allescheria boydii, and Sporotrichum schenckii in a series of laboratory studies. Preliminary agar dilution plate tests indicated that Lanstan, DAC 649, DAC 469, DAC 2787, He 3944, maneb, and nabam, in order of decreasing activity, inhibited all test fungi. Terraclor, Dexon, and He 13274 were active only in high concentration. The best fungicidal properties were exhibited by Lanstan, Vapam, and DAC 649; maneb, nabam, DAC 469, and DAC 2787 were fungicidal but to a lesser degree than the former compounds. In subsequent tests against H. capsulatum and C. neoformans in artificially infested soil or by use of the buried plug technique, Lanstan, Vapam, and DAC 649 showed good activity and merit further study.

Antifungal Agents↗
PubMed2005

Early environmental origins of neurodegenerative disease in later life.

Parkinson disease (PD) and Alzheimer disease (AD), the two most common neurodegenerative disorders in American adults, are of purely genetic origin in a minority of cases and appear in most instances to arise through interactions among genetic and environmental factors. In this article we hypothesize that environmental exposures in early life may be of particular etiologic importance and review evidence for the early environmental origins of neurodegeneration. For PD the first recognized environmental cause, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), was identified in epidemiologic studies of drug abusers. Chemicals experimentally linked to PD include the insecticide rotenone and the herbicides paraquat and maneb; interaction has been observed between paraquat and maneb. In epidemiologic studies, manganese has been linked to parkinsonism. In dementia, lead is associated with increased risk in chronically exposed workers. Exposures of children in early life to lead, polychlorinated biphenyls, and methylmercury have been followed by persistent decrements in intelligence that may presage dementia. To discover new environmental causes of AD and PD, and to characterize relevant gene-environment interactions, we recommend that a large, prospective genetic and epidemiologic study be undertaken that will follow thousands of children from conception (or before) to old age. Additional approaches to etiologic discovery include establishing incidence registries for AD and PD, conducting targeted investigations in high-risk populations, and improving testing of the potential neurologic toxicity of chemicals.

Age Factors↗
PubMed1999

The toxicity of dithiocarbamate fungicides to soil nematodes, assessed using a stress-inducible transgenic strain of Caenorhabditis elegans.

The dithiocarbamate fungicides maneb and mancozeb induce a short-term stress response in a transgenic Caenorhabditis elegans strain (PC72) carrying a reporter lacZ gene under the control of a homologous heat shock (hsp16) promoter. This response can be readily monitored as induced beta-galactosidase activity, either by in situ staining or by a quantitative fluorometric enzyme assay. Particularly strong responses are induced by mancozeb (three- to fivefold above controls at 500 microg mL(-1)), causing acute toxicity at concentrations comparable to those recommended for field application (2 mg mL(-1)). Although much of this fungicide is adsorbed by soil, sufficient (ca. 6%) enters the soil water compartment to cause mild stress in the transgenic worm assay. Among possible metabolites from mancozeb breakdown, neither Mn2+ nor ethylenethiourea (ETU) is particularly toxic even at 10% of the optimum mancozeb dosage. Stress responses to a range of other pesticides are also reported, and in several cases it is clear that a nontarget soil species (here, transgenic C. elegans) may be sensitive to low-level contamination.

Animals↗
PubMed1977

Inhibits of of colon carcinogenesis.

Disulfiram (tetraethylthiuram disulfide, Antabuse) and sodium diethyldithiocarbamate, when added to the diet, inhibit 1,2-dimethylhydrazine (DMH)-induced neoplasia of the large bowel in female CF1 mice. Ethylene bis(dithiocarbamato)manganese (Maneb) and bis(ethylxanthogen), two pesticides with structural similarities to disulfiram, produce comparable inhibition of DHM. In other work, disulfiram was found to inhibit the carcinogenic effect of azoxymethane (AOM) on the large bowel. Under comparable conditions the inhibition of AOM was considerably less than that obtained with DMH as the carcinogen. The data suggest that disulfiram inhibits DMH metabolism at more than one oxidative step.

Animals↗
PubMedDate not supplied

Development of a field bioassay for the side effects of pesticides on decomposition.

A method has been developed for assessing the side effects of fungicides on decomposition using litterbags. Twenty dried leaf disks of Chinese cabbage, Brassica oleracea, were placed in litterbags (20 x 20 cm) made of nylon fabric (25 microns mesh). The litterbags were laid in a treated plot and 5, 10, 20, and > 200 m from the treated plot and covered with 1 cm of standard soil. After 1 week, the dry weight of the leaf disks was determined. In an iterative procedure the method was optimized and significant differences of 5% in decomposition rate between litterbags were found using the final method presented here. In and around agriculturally managed plots, negative effects on decomposition of two fungicides could be traced. Effects on decomposition were found after application of captan (in fruit, 1.5 kg a.i./ha) and maneb (in potatoes, 3 kg a.i./ha) up to 10 m from the treated plot, at moderate wind speeds (3-5 m/s). In one case the concentration of captan in the soil covering the litterbags was measured. A negative correlation was established between captan concentration and decomposition. These experiments were repeated in an experimental plot under more controlled conditions with respect to the amount and time of application. The results of the field experiments could not be reproduced on the experimental plot. Additional experiments with soil fungi in agar again demonstrated a significant effect of exposure to captan, however. Given the results, the method using litterbags requires further development before a standard field trial can be designed. Given the knowledge gained with respect to the key factors involved, a bioassay using soil fungi seems to have high potential, however.

Biodegradation, Environmental↗
PubMed1996

Toxicity of fungicides containing ethylene-bis-dithiocarbamate in serumless dissociated mesencephalic-striatal primary coculture.

Agricultural exposure to the organomanganese fungicide MANEB (manganese-ethylene-bis-dithiocarbamate) may induce an extrapyramidal syndrome resembling parkinsonism. To evaluate the relative role of manganese (Mn) and ethylene-bis-dithiocarbamate (EBDTC) in the hazard of organomanganese fungicides, we studied the effects of MANCOZEB (Mn-Zinc-EBDTC) and ZINEB (Zinc-EBDTC) on serumless dissociated mesencephalic-striatal primary coculture. High affinity 3H-dopamine (DA) and 14C GABA uptakes as well as immunocytochemical staining of tyrosine hydroxylase (TH)-containing cells were used as specific functional markers of DA and GABA neuron viability. Both MANCOZEB and ZINEB, at 10 and 50 microM concentrations, dose dependently reduced DA and GABA viability parameters. These data suggest that EBDTC rather than Mn may be primarily responsible for the cytotoxicity of organomanganese fungicides on neuronal systems relevant to the pathophysiology of parkinsonism.

Animals↗
PubMed1985

Studies on the toxicity of some carbamate fungicides in Drosophila melanogaster Meig. (Insecta, Diptera).

This paper reports the effects of three commercial powders mixed into the diet, Dithane M-45 (mancozeb 80%), Pomarsol (thiram 80%) and Peltar (maneb 50% and methyltiophanate 25%) on survivorship of adults Drosophila and on the progeny. With wild-type adults (Oregon), fungicides were added to the diet at the rate recommended on the label. The mean lifespan was reduced by 42.5% (Pomarsol), 50% (Dithane M-45), and 83% (Peltar). For larvae of two strains (Oregon and triploid) intoxicated with Dithane M-45 and Peltar, a linear relationship was demonstrated between the doses and the percentage of the progeny reduction. The calculated doses inducing a 50% reduced progeny (PR50) are in the range of 400 to 700 ppm. With Pomarsol in the range of 500 to 1500 ppm and for the both strains, the progeny was decreased by about 60%. A very reduced size and a leg paralysis was observed with each toxic powder for Oregon and triploid flies. It appears that a triploid stock of chromosomes does not significantly modify the reaction of the flies.

Animals↗