Benzidine and 3,3'-dichlorobenzidine (DCB) induce micronuclei in the bone marrow and the fetal liver of mice after gavage

Single oral dose of benzidine (300 mg/kg) and DCB (1000 mg/kg) to male ICR mice elicited positive response in the bone marrow micronucleus test. In the transplacental micronucleus test, the compounds were administered to pregnant females in the same manner. A significant increase in the frequency of micronuclei occurred in the fetal liver, but not in the bone marrow of mothers. The relative values of bone marrow and transplacental micronucleus tests for the prediction of carcinogenicity of these compounds is discussed.