Abstract: Objective: To clarify the genotoxicity induced by acute exposure of ozone with different concentrations on pulmonary cells in rats. Methods: Thirty-six Wistar rats were randomly divided into control group (filtered air exposure) and ozone exposure group (0.12 ppm, 0.5 ppm, 1.0 ppm, 2.0 ppm, 4.0 ppm) with 6 in each group. After rats were exposed to different concentrations of ozone for 4 h, lung tissues were taken and single cells were isolated. Then, 8-hydroxydeoxyguanosine (8-OHdG) was quantitatively detected by enzyme-linked immunosorbent assay. Comet assay, micronucleus test and DNA- protein cross-linking assay were used to analyze DNA and chromosome damages. Results: Compared with the control group, the content of 8-OHdG in lung tissue was increased significantly from the ozone exposure concentration of 0.12 ppm, reaching the highest value at 0.5 ppm. With the increase of ozone exposure concentration, the tail rate of comets was increased gradually, and there was a significant dose-effect relationship. The cross-linking rate of DNA- protein was increased first and then was decreased with a maximum value at 2.0 ppm group. Although the micronucleus rate of lung cells showed an upward trend, there was no significant difference compared with the control group. Conclusion: Acute exposure of ozone at low concentrations (0.12 ppm) could lead to DNA damage in the pulmonary cells of rats, while no significant chromosome damage was found even in the group with ozone concentration reached to 4 ppm.

Key words: ozone, acute exposure, genotoxicity, lung tissue, rat