摘要：The mutagenic activity of size-fractionated atmospheric particulate matter (PM) was investigated at both a roadside site and a suburban site in Saitama, Japan. Sampling was carried out using a low-pressure cascade impactor between January and February 2005. The mutagenic activity of the size-fractionated PM was determined by the Ames test using Salmonella typhimurium strain TA98 without metabolic activation (S9). Most of the mutagenic activity was found in the fine particle fraction (< 2.1 μm) at both sites. There was almost no difference in the contribution of fine particles to the mutagenic activity of total PM between the two sites. On the other hand, there was a clear difference in the contribution of ultrafine particles (< 0.12 μm) to the mutagenic activity between the two sites. At the suburban site, ultrafine particles accounted for 5.7% of the mutagenic activity of total PM. In contrast, at the roadside site, ultrafine particles contributed as much as 12% to the mutagenic activity of total PM, although their contribution to the total PM mass was only 2.3%. Moreover, the mutagenic activity per unit air volume in the ultrafine particle fraction at the roadside site (1.2 revertants/m3) was 3.1-fold higher than that at the suburban site (0.38 revertants/m3), although the activity in the fine particle fraction at the roadside site was only 1.4-fold higher than that at the suburban site. These results indicated that, with regard to mutagenicity, the health risk due to ultrafine particles is relatively high at roadside areas.
关键词：ultrafine particle;mutagenic activity;roadside;size distribution
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