In vitro mutagenicity assays of chemical carcinogens and related compounds with Salmonella typhimurium.

The mutagenic activity of 101 chemicals was studied with the use of the Salmonella typhimurium-microsome system described by Ames. The tester strains were TA1535, TA1536, TA1537, TA1538, TA98, and TA100. Assays were conducted in the presence and absence of a metabolic activation system prepared from the livers of randomly bred Sprague-Dawley rats that had been pretreated with Aroclor 1254. The test chemicals were incorporated into the agar with bacteria and the metabolic activation system. Mutagens were defined as chemicals that induced a reproducible dose-related increase in the number of histidine-independent revertants. With the use of these procedures, 65% of the organic carcinogens and 25% of the noncarcinogens were found to be mutagenic.