Detection of oxidative mutagens in an urban air-particulate extract: a preliminary study

The Ames assays strains TA98 and TA100 have been useful in characterizing complex mixtures from organic solvent extracts of particles from diesel-powered vehicles, ambient air, and other sources. In this paper we report preliminary experiments using TA102, a bacterial strain that detects compounds that can oxidize DNA, to characterize the mutagenicity of an ambient air sample collected in Ann Arbor, MI. Four sets of ambient air filters were collected in duplicate over a period of several days. The mutagenicities of methylene chloride extracts of these filters were compared using strains TA98, TA100 and TA102. The concentration-mutagenicity data for TA98 and TA100 were linear over the concentration range 0-200 micrograms extract/plate. The mutagenicity of the extracts using TA102 was much lower than the other two strains and was non-linear over the concentration range tested. These results suggest that it would be difficult to use TA102 to identify the oxidative mutagens present in an ambient air particulate extract.