Objective: Comparing the genotoxicity of gasoline-fueled vehicle exhaust (gasoline exhaust for short) with that of methanol-fueled vehicle exhaust (methanol exhaust for short) so as to provide a scientific basis for replacement of gasoline by methanol as fuel in vehicle.
Methods: The MTT method was used first to evaluate the cytotoxicity of the two kinds of vehicle exhausts, and the concentration that had no obvious cytotoxicity would be used as the highest dose in the experiments. The A549 cells micronucleus test and single cell gel electrophoresis (SCGE) assay (comet assay) in vitro were applied to compare the genotoxicity of gasoline exhaust and methanol exhaust.
Results: The MTT results showed that the gasoline-fueled vehicle exhaust exerted stronger cytotoxicity to A549 cells in both 2 h and 24 h exposure times, compared with the methanol exhaust. In A549 cells micronucleus test in vitro, at doses 0.025, 0.05, 0.1 and 0.2 L/ml, the micronucleated cell (MNC) rates were 2.65%, 4.35%, 4.95% and 5.85% respectively, which were higher than those (1.30% and 1.35%) of controls (P<0.01). For the methanol-fueled vehicle exhaust, there was no significant difference in the rate of A549 cells micronucleus between the test groups and control group. In the comet assay, gasoline-fueled vehicle exhaust could induce A549 cells DNA damage. The rate of caudate cell and the length of DNA migration increased with the escalation of dosing level. However, the methanol-fueled vehicle exhaust did not show any DNA damage to A549 cells.
Conclusion: The results demanstrate that gasoline-fueled vehicle exhaust can induce DNA and chromosome damage, it has a distinct genotoxicity, whereas the methanol-fueled vehicle exhaust does not show any potential genotoxicity in both tests.