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.
D000818:Animals; D002802:Cholinesterases / Q000032:analysis; D004006:Dichlorvos / Q000633:toxicity*; D005260:Female; D006128:Growth / Q000187:drug effects; D008297:Male; D009369:Neoplasms / Q000139:chemically induced*; D051381:Rats; D012137:Respiratory System / Q000187:drug effects; D012737:Sex Factors
D004006:Dichlorvos; D002802:Cholinesterases