| Abstract: | Airborne particulates collected from urban and non-urban air were extracted with calf serum or benzene, and their mutagenic potencies were evaluated in the Salmonella reversion assay. The serum extracts were mutagenic to strains TA98 and TA100 and contained both direct- and indirect-acting mutagens. Mutagenic activities for TA98 recovered from the particulates by serum or benzene extraction were much less in the serum extracts than in the benzene extracts. There was no significant difference in mutagenic potencies of the extracts between the urban and non-urban particulates, irrespective of the presence of S9 mix. The calculated mutagenic activities per m3 of air, however, were greater for urban air than for non-urban air, because of higher concentration of particulates in urban air than in non-urban air. Serum effectively reduced both direct and indirect mutagenic activities of the benzene extracts except for an insufficient reduction in direct mutagenicity at a high dose of benzene extracts. These findings suggest that serum could contribute greatly to decrease the mutagenicity of airborne particulates by mechanisms such as less efficient solubilization of mutagenic components and inactivation by protein binding. Biological availability of mutagens, therefore, should be considered for evaluation of actual mutagenic hazard by airborne particulates. |
