Mutagenic and chemical assay of extracts of airborne particulates

Abstract

The mutagenic activity of extracts of airborne particulates was evaluated in the Salmonella system. The mutagenicity of airborne particulates was not always correlated with the content of benzo[ a]pyrene (B[ a]P) in the complex mixtures, especially when the samples were collected at different sites. Large-scale fractionation of extracts of airborne particulates was used to determine the content of specific mutagenic chemicals. The neutral fraction of material soluble in cyclohexane and nitromethane contained the polycyclic aromatic hydrocarbon (PAH) compounds, which accounted for 27.9% of the mutagenic activity of the whole extracts. 9 kinds of PAH compound were identified quantitatively by thin-layer chromatography. They included, per 1000 m 3 of air, 12.6 μg of benzo[ e]pyrene (B[ e]P), 10.7 μg of chrysene (CHRY), 10.0 μg of fluoranthene (FL), 6.43 μg of benzo[ ghi]perylene (B[ ghi]P), 5.75 μg of benz[ a]anthracene (B[ a]A), 5.33 μg of B[ a]P, 3.38 μg of pyrene (PYR), 1.83 μg of coronene (COR), and 1.34 μg of perylene (PERY). Mutagenicity of the ether-soluble acidic, basic and methanol-soluble neutral fractions accounted for 10.9, 9.71 and 6.78% of the total mutagenic activity of crude extract, respectively, when assayed in strain TA98 with liver S9 fraction. The total recovery of mutagenic activity after fractionation was 58%. Two acidic fractions (weak and strong ether-soluble acids) and the methanol-soluble neutral fraction reverted strain TA98 dramatically to prototrophy in the presence of rat-lung S9 fraction more than liver. But the mutagenic chemicals in these fractions remain to be clarified. Direct mutagens were present in essentially all fractions. The particulates, which had diameters ranging from 0.3 to 1.0 μm and were able to penetrate alveoli, contained a high content of mutagens.