Kinetics of benzo[a]pyrene induced mutagenesis in a highly sensitive salmonella/microsome assay.

The kinetics of benzo[a]pyrene induced mutagenesis in Salmonella typhimurium TA98 and TA100 were studied using a liquid-phase assay and were compared to kinetics of metabolism of benzo[a]pyrene in the same system. Mutagenesis was terminated by the addition of pyrene + menadione at selected times. Under conditions of the assay using hepatic microsomes from 3-methyl-cholanthrene pretreated rats, metabolism of benzo[a]pyrene was over 50% complete in 5 min, and metabolism of initial metabolites became appreciable after this time. The revertant frequency (revertants/10(8) survivors) and the production of tertiary metabolites increased sharply after 5 min and leveled off at 40 min.