zineb and Cocarcinogenesis

The carcinogenic potential of 5 pesticides was analyzed using a medium-term multi-organ bioassay for carcinogenicity. Male F344 rats were initially treated with 3 known carcinogens (diethylnitrosamine, N-methyl-N-nitrosourea and N-bis(2-hydroxypropyl)nitrosamine) during a period of 4 weeks to induce neoplastic changes in a variety of organs, and then given one of 5 pesticides in the diet for a further 16 weeks. Neoplastic and pre-neoplastic lesions were found in the thyroid, kidney and urinary bladder with propineb, in the forestomach, kidney and thyroid with captan and folpet. The number of glutathione S-transferase placental-form-positive liver-cell foci was significantly increased in the captan- and phosmet-treated groups. Based on these findings, captan and propineb can be considered as carcinogens and carcinogenicity is suspected for folpet and phosmet. These results are in concordance with reported long-term carcinogenicity for captan, folpet and propineb. Daminozide was considered not to be carcinogenic. Thus, the present assay of 20 weeks' duration is useful for the prediction of potential carcinogens.

Topics: Animals; Body Weight; Captan; Carcinogenicity Tests; Carcinogens; Cocarcinogenesis; Diethylnitrosamine; Liver; Liver Neoplasms, Experimental; Male; Methylnitrosourea; Models, Biological; Nitrosamines; Organ Size; Pesticides; Precancerous Conditions; Rats; Rats, Inbred F344; Zineb

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Cocarcinogenesis; Female; Fungicides, Industrial; Maneb; Mice; Skin Neoplasms; Thiocarbamates; Zineb

In this study the tumour-promoting activity of a carbamate fungicide, mancozeb, has been observed following topical application on mouse skin in a two-stage initiation--promotion protocol for carcinogenesis. Female Swiss albino mice were initiated with a single subcarcinogenic dose (52 micrograms) of 7,12-dimethylbenz[a]anthracene painted on the interscapular region. Seven days after initiation the mice underwent topical application of mancozeb (100 mg/kg body wt) three times per week as promoter. Development of tumours was observed after 12 weeks of mancozeb application in 1/14 animals and 100% tumorigenesis was recorded after 17 weeks of mancozeb application. On histological examination, these tumours were found mostly to be benign in nature, e.g. squamous cell papillomas and keratocanthomas.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Cocarcinogenesis; Female; Fungicides, Industrial; Maneb; Mice; Skin Neoplasms; Thiocarbamates; Zineb