MUTAGENICITY OF AIRBORNE-PARTICULATES IN ALLEGHENY COUNTY - UNMASKING OF POTENTIAL CARCINOGENICITY BY SIZE CLASS FRACTIONATION

Acetone extracts of crude and size-classified airborne particulates were tested for mutagenicity using the Ames Salmonella typhimurium microsomal bioassay. Both direct and indirect acting frameshift and base-substitution mutagens were detected. Size fractionation unveiled direct and indirect acting mutagens which were concealed in the crude preparation, and demonstrated that the mutagenic potential of the crude extract increased as the particle size decreased (0.95-0.49 mum). The mutagenicity observed in this fraction increased by approximately 1.8-fold and 2.0-fold of that found in the crude extract of the same sampling site with S-9 activation, thus warranting further study of the mutagenic interactions present in complex environmental airborne pollutants. Approximately 41.4% of the deposited particulate mass was extractable by acetone. Furthermore, 67% of this extractable mass was derived from particles of < 1.5 mum diameter which contained the bulk (73%) of mutagenic activity.