Abstract: OBJECTIVE: To investigate the genotoxic effects of extractable organic matter (EOM) from coke oven emissions (COEs) and motor vehicle exhausts on human hepatoma HepG2 cells. METHODS: After treated with different concentrations of coke oven- and traffic-EOMs,the genotoxic damage in HepG2 cells were evaluated by comet assay and cytokinesis-block micronucleus cytome assay. RESULTS: Significant dose-dependent increases in Olive tail moment, tail DNA (%),and tail length were observed in both coke oven- and traffic-EOMs treated HepG2 cells,except for the Olive tail moment in 0.006 ng/L traffic-EOMs treated group. The micronuclei and nucleoplasmic bridges frequencies induced by 5.5 μg/L of coke oven EOM increased to a maximum of 3.6 and 2.5 folds,respectively. Coke oven EOM led to a significant increase in nuclear buds frequency that progressively increased to 2.3 fold of the control level after 24 h treatment. The traffic-EOM showed appreciable increases in micronuclei and nucleoplasmic bridges frequencies over the controls across a range of concentration (0.6-626.3 ng/L). However,compared with the control group,only 63 and 626.3 ng/L traffic-EOM led to significant increases in nuclear buds frequency in HepG2 cells. CONCLUSION: Both the coke oven- and traffic-EOMs could induce DNA strand breaks and genomic instability in the metabolically competent HepG2 cells. The comet assay could provide a sensitive method for rapid screening of the genotoxicity of low concentrations of environmental complex mixtures.

Key words: coke oven emissions, motor vehicle exhausts, DNA strand breaks, chromosome damage, genotoxicity