Mutagenesis in Salmonella after metabolic activation of carcinogenic azo dyes and their isomers by liver S9 from rats, mice and hamsters.

The mutagenicities of 3'-methyl-N,N-dimethyl-4-aminoazobenzene (3'-Me-DAB) and 3'-CH2OH-DAB, potent hepatocarcinogens, activated by rat-liver S9 were compared with those of their isomers (2'- or 4'-substituted DAB) and with those obtained with liver S9 from mice, hamsters and man. All 6 aminoazo dyes showed positive mutagenicity on both strains TA98 and TA100 in the presence of liver S9 from rats pretreated with polychlorinated biphenyls (PCB) whereas 3'-Me-DAB and 3'-CH2OH-DAB were negative in the presence of S9 from other organs of rats and human liver. 3'-Me-DAB and 3'-CH2OH-DAB also showed negative or only a weak mutagenicity in the presence of liver S9 from non-treated animals. Treatment of the muta-carcinogens by liver S9 from PCB-treated mice or hamsters exerted mutagenicity on TA98, but less than that seen with rat-liver S9. The activity of 3'-Me-DAB in the presence of female rat-liver S9 was lower than that obtained with the male. Thus a specificity in the aminoazo dye carcinogenesis in regard to species, sex and organ was also observed in the mutagenic effects of 3'-Me-DAB on Salmonella.