Characteristics of the transformation frequency at the tumor promotion stage of airborne particulate and gaseous matter at ten sites in Japan.

We used a high-volume air sampler in the summer of 2007 and the winter of 2008 at ten Japanese sites (Sapporo, Sendai, Maebashi, Tsukuba, Shinjuku, Sagamihara, Shizuoka, Touhaku, Kitakyushu, and Kagoshima) to collect total suspended particulate (TSP) and gaseous matter for evaluation. We evaluated the transformation frequency at the tumor promotion stage of these samples in a cell transformation assay using Bhas 42 cells, which were established from BALB/c 3T3 cells transfected with the v-Ha-ras oncogene. All samples collected from the gaseous matter were negative for transformed foci.