Mutagenic activity of airborne particulate organic pollutants

Organic extracts of airborne particulates collected at eight urban locations and one nonurban site in Southern California were analyzed for mutagenic activity using Ames' Salmonella typhimurium assay system. All urban samples exhibited mutagenic activity, confirming initial findings. The activity was observed with strains susceptible to frameshift mutation and was not enhanced by the addition of a mammalian metabolic activation system, thus suggesting the presence of mutagens other than benzo(a)pyrene and other polycyclic hydrocarbons which require metabolic activation. Assay of 0.1 to 1 mg of the samples resulted in a 5- to 20-fold increase in his⁺ revertants above the background level, with the number of revertants per plate ranging from 0.10 to 0.44 per μg of organic carbon tested.