Objective To investigate the effects of DDT and nano-TiO2 on ROS level and DNA damage in human embryo liver L-02 cells.
Methods L-02 cells were exposed separately to different doses of DDT(0.001, 0.01, 0.1 μmol/L), nano-TiO2 (0.01, 0.1, 1 μg/mL), and different concentration of DDT mixed with nano-TiO2 respectively for 24 h. Reactive oxygen species(ROS) level was determined by flow cytometry and DNA damage was measured by alkali and neutral comet assay.
Results It was observed that exposure to DDT greater than 0.01 μmol/L or 1 μg/mL nano-TiO2 alone could significantly increase ROS production compared with control cells(P<0.05). In alkaline comet assay, no significant effects on DNA damage were observed in single nano-TiO2 groups(P>0.05), but 0.01 μmol/L concentration of DDT or higher could induce DNA damage(P<0.05). However, there was no statistically significant increase of OTM in all groups compared with control group in neutral comet assay(P>0.05). Mixture of DDT and nano-TiO2 was synergistic to increase ROS generation and DNA single strand breaks(P<0.05).
Conclusion Combination of DDT and nano-TiO2 enhanced their capability synergistically in DNA single strand breaks of L-02 cells. The primary mechanism of toxicity may be that DDT and nano-TiO2 can induce the free radical generation, followed by DNA damage.
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