Mutagenicity of soot and associated polycyclic aromatic hydrocarbons to Salmonella typhimurium.

The mutagenic activity of the polycyclic aromatic hydrocar bon-containing fraction of several soot samples was measured in Salmonella typhimurium, using resistance to the purine analog 8-azaguanine as a genetic marker. A postmitochondrial supernatant derived from livers of phénobarbitaland/or Aroclor-pretreated male Sprague-Dawley rats was incorporated into all assays to allow metabolism of promutagens to their active forms. The mutagenic activity of the soot extracts ranged from 10 to 20 times higher than could be accounted for by the amount of benzo(a)pyrene present. The possibility that synergism oc curs between benzo(a)pyrene and some component in the soot extracts was discounted by the finding of a simple additive relationship of mutagenicity of a soot extract and added benzo(a)pyrene. To examine the alternative explanation that other compo nents of soot may have undiscovered mutagenic activity, 70 polycyclic aromatic hydrocarbons were quantitatively assayed for their mutagenic potential; 34 of these compounds induced a significant increase in the mutant fraction resistant to 8azaguanine. Of particular interest are the extreme mutagenicities of perylene, cyclopenta(ccOpyrene, and fluoranthene, all of which exhibit greater mutagenicity than does benzo(a)pyrene at equimolar concentrations. Using the measured activities of each polycyclic aromatic hydrocarbon constituent in a kerosene soot, we are able to account for the mutagenic activity of the whole polycyclic aromatic hydrocarbon fraction in terms of the additive muta genicity of its individual components.