Carcinogenicity study of 3,3′-dimethylbenzidine dihydrochloride in BALB/c mice

Abstract

BALB/c mice (120/sex/dose) were given 0, 5, 9, 18, 35, 70 or 140 ppm of 3,3′-dimethylbenzidine dihydrochloride in their drinking-water and killed after 13, 26, 39, 52, 78 or 116 wk. Full histopathological evaluations were performed on all animals that were found dead or moribund, or that were killed on schedule. Fatal lung alveolar cell neoplasms began to appear in males receiving 140 ppm at 78 wk and there was a significant dose-related decrease in the time-to-death from this cause. There were no significant dose-related trends for this neoplasm in females, nor were there treatment-related effects on body weight, water consumption or other lesions in either sex. This is the first report of a neoplastic response to 3,3′-dimethylbenzidine dihydrochloride in mice.