Carcinogenic effect of combined administration of 2,4-diaminoanisole sulfate, 4,4'-thiodianiline and N,N'-diethylthiourea in male Wistar rats.

Male Wistar rats were divided into two groups. Rats of group 1 were fed basal powdered diet containing 610 ppm 2,4- diaminoanisole sulfate (DAAS), 46 ppm 4,4'-thiodianiline (TDA) and 200 ppm N,N'-diethylthiourea (DETU) for 52 weeks (DTD treatment). Rats of group 2 were maintained on basal diet throughout the experiment as controls. At 52 weeks all surviving rats were sacrificed and subjected to an autopsy. Thyroid, lungs, stomach, liver, spleen, kidneys, testes and all gross lesions suspected of being a tumor were removed. After DTD treatment, the incidence of thyroid hyperplasia and papillary thyroid carcinoma was 59% (10/17) and 65% (11/17), respectively. Hepatocellular adenoma was induced in 2 of 17 rats (12%). Papillary thyroid carcinoma metastasis was found in the lung of 1 rat. No neoplastic tumors were found in kidney, spleen, stomach and testis tissue.