Oncogenic Evaluation of 3,3′-Dimethoxybenzidine Dihydrochloride in BALB/c Mice

Abstract

3,3′-Dimethoxybenzidine, a congener of the known carcinogen benzidine, is carcinogenic in the rat and possibly the hamster. This study was undertaken to assess carcinogenicity in an inbred mouse strain. Male and female (840 each) BALB/c mice were given 0, 20, 40, 80, 160, 315, or 630 ppm of 3,3′-dimethoxybenzidine dihydrochloride in their drinking water. At the serial sacrifices (13, 26, 39, 52, 78, or 112 weeks on dose), detailed necropsies and histopathologic examinations were performed. There was a decrease in water consumption at the 630 ppm dose level. Compared with controls, the 630 ppm dose produced a decrease in body weight gain of 10.7 and 13.3% in males and females, respectively, at 48 to 52 weeks on test. These weight decrements may be related to low water palatability at the 630 ppm dose level and may not reflect toxicity induced by 3,3′-dimethoxybenzidine itself. There was no treatment-related effect upon mortality or pathology. In summary, 3,3′-dimethoxybenzidine dihydrochloride was not carcinogenic in the mouse in the current investigation.