Chemical characterization of direct-acting airborne mutagens: the functional group

Durham NC air was sampled, extracted, and bioassayed for mutagenic activity in Salmonella typhimurium TA98. Portions of the extracts were treated with sodium borohydride over copper (II) acetylacetonate to reduce any nitroaromatic substances to their corresponding amines. All of the reduced extracts were not directly mutagenic, but the 2 that were derived from cold-weather air samplings did contain substances that could be activated oxidatively. These "indirect-acting" mutagens were present in the same 2 reduced extracts that contained detectable concentrations of aromatic amines. These results suggest that a major portion of the total mutagenic activity in air-pollution particles is contributed by nitro-substituted compounds that are detectable as their corresponding amines. They also suggest that the atmospheric concentrations of these substances may be high in the colder months of Durham's year.