Mutagenicity spectra in bacterial strains of airborne and engine exhaust particulate extracts.

The mutagenicity spectra of the organic extracts of both airborne particulate matter and diesel and gasoline soot particles were determined using a battery of 9 bacterial strains of different genetic specificity. The assays with crude extracts and with fractionated acidic, neutral and basic components revealed striking differences in the patterns of mutagenic responses produced by each of the complex mixtures investigated. The mutagenicity of air particulate matter was shown to depend mainly on direct-acting acidic and neutral compounds, with a lesser contribution of basic promutagens which required exogenous metabolic activation by liver S9. The assays with a diesel soot extract indicated the prevailing contribution of direct-acting acidic and neutral compounds, and suggested an important role also for nitro derivatives other than nitropyrenes. The gasoline exhaust was characterized by powerful promutagenic compounds, belonging to either the acidic, neutral or basic fractions. The implications of these results are discussed with respect to the contribution of engine exhausts to air pollution, and the possible use of mutagenicity spectra in the analysis of environmental complex mixtures.