Mutagenicity of various organic fractions of diesel exhaust particles.

Treated with various organic fractions of Diesel Exhaust Particles (DEP), the Ames test withSalmonella typhimurium strains TA98 and TA100, and the mice micronucleus test were employed to study the mutagenic activity in the bacterial reverse mutation system, with and without a mammalian S(9) activation component, and the clastogenic activity in mice polychromatic erythrocyte (PCE) stem cells. Extracted ultrasonically with dichloromethane then using the acid and base separated reaction and column chromatography, DEP were divided into five organic fractions. They are the organic acid fraction (Fl), the organic base fraction (F2), the aliphatic hydrocarbon fraction (F3), the aromatic hydrocarbon fraction (F4) and the polar fraction (F5). Results showed that an increase in the counted numbers of histidine revertants on theSalmonella TA100 and TA98 was observed with or without (S(9) mix), but these activities were more pronounced in the TA98 strains especially in the absence of the S(9) mix. These results suggest that the organic fractions of DEP contain mainly compounds with direct frame-shift mutaganicity. Positive results were also obtained from mice micronucleus assay. The frequency of mice bone marrow micronucleated polychromatic erythrocytes (PCE) was increased using this assay and it showed a definite dose-response relationship. The results suggest that various organic fractions could affect spindle fiber function or formation in mammalian cells. Compared with the results of different organic fraction, the effects of the F2, F4 and F5 were found to be stronger than those of other fractions. Based on the findings obtaind in the Ames and micronucleus tests, DEPs have genotoxic effects in both of the test systems.