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

Acetone extracts of crude and size-classified airborne particulates we re tested for mutagenicity using the Ames Salmonella typhimurium micro somal bioassay. Both direct and indirect acting frameshift and base-su bstitution mutagens were detected. Size fractionation unveiled direct and indirect acting mutagens which were concealed in the crude prepara tion, and demonstrated that the mutagenic potential of the crude extra ct increased as the particle size decreased (0.95-0.49 mum). The mutag enicity 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 s ite with S-9 activation, thus warranting further study of the mutageni c interactions present in complex environmental airborne pollutants. A pproximately 41.4% of the deposited particulate mass was extractable b y acetone. Furthermore, 67% of this extractable mass was derived from particles of < 1.5 mum diameter which contained the bulk (73%) of muta genic activity.