DIFFERENCES OF MUTAGENIC ACTIVITY OF AIRBORNE-PARTICULATES BY PARTICLE-SIZE - ASSAY BY THE SALMONELLA MICROSUSPENSION PROCEDURE

The mutagenicity of airborne particulates in Tokyo was evaluated by the Salmonella microsuspension procedure. Airborne particles were collected in 9 collection stages according to their aerodynamic diameter and tested for the mutagenicity with S. typhimurium strain TA 98. Because the microsuspension procedure is highly sensitive, it was possible to detect the mutagenic activity from only 10 mug of the particles of less than 2.5 mum in diameter. Moreover we could detect the mutagenic activity of the particles ranging from 2.5 to 10 mum, which had been difficult to be detected by the original Ames test. The particles collected in winter showed higher activity than those in summer. The mutagenic activity was high in the particles of less than 0.4 mum and of about 1 mum in winter. In the same season, the specific activity for the mutagenicity of the particulates did not differ in the sampling area. The concentration of polyaromatic hydrocarbons in airborne particulates correlated with the mutagenicity of those in every collection stage, and it was suggested that mutagens in particulate matter behave as polyaromatic hydrocarbons.