MUTAGENICITY OF SOME OF THE PROPOSED METABOLITES OF DIRECT BLACK 38 AND PIGMENT YELLOW 12 IN THE SALMONELLA-TYPHIMURIUM ASSAY SYSTEM

The Ames Salmonella/mammalian microsome assay system was used to evaluate the mutagenic potential of some of the proposed metabolites of Direct Black 38 and Pigment Yellow 12. Direct Black 38, benzidine, 4-aminobiphenyl, monoacetylbenzidine, and diacetylbenzidine were mutagenic for at least one of the tester strains after metabolic activation with mouse liver S-9 fractions. The proposed metabolites of Pigment Yellow 12, namely dichlorobenzidine, monoacetyldichlorobenzidine and diacetyldichlorobenzidine were strongly mutagenic for Salmonella typhimurium TA 98. The major metabolite in the urine from hamsters given a single dose of Direct Black 38 (100 mg/kg) was found to be monoacetylbenzidine. Monoacetylbenzidine and the urine from the animals treated with Direct Black 38 were active in the Ames test only after S-9 fraction was added to the test mixture. © 1979.