title: Oxidative stress and DNA damage in the earthworm Eisenia fetida induced by toluene, ethylbenzene and xylene.
abstract: Superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and the comet assay (SCGE) were used as biomarkers to evaluate the oxidative stress and genotoxicity of toluene, ethylbenzene and xylene in earthworms (Eisenia fetida). The results indicated that the exposure of the three pollutants caused a stress response of the three enzymes, an approximate bell-shaped change (a tendency of inducement firstly and then inhibition with increasing concentrations of the pollutants) was mostly found. The three enzymes tested differed in their sensitivity to different pollutants. While the activity of POD was not significantly changed within the concentration range, the concentration thresholds for significant (P < 0.05) responses to toluene based on SOD and CAT were 5 mg kg(-1), respectively. Similarly, the concentration thresholds for significant (P < 0.05) responses to ethylbenzene based on CAT and POD were 10 and 5 mg kg(-1), respectively, while the activity of SOD was not significantly changed within the concentration range. Significant responses to xylene based on CAT and POD were 5 mg kg(-1), respectively, while the activity of SOD was significantly (P < 0.05) induced at 10 mg kg(-1). The SCGE assay results showed that these three pollutants could significantly (P < 0.01) induce DNA damage in earthworms and the clear dose-dependent relationships were displayed, indicating potential genotoxic effects of toluene, ethylbenzene, and xylene on E. fetida. The inducement of DNA damage may be attributed to the oxidative attack of toluene, ethylbenzene, and xylene. Toluene seemed to be more genotoxic as it could induce the higher extent of DNA damage than ethylbenzene and xylene. The results suggest that the SCGE assay of earthworms is simple and efficient for diagnosing the genotoxicity of pollutants in terrestrial environment.
authors.affiliation: Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education/College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Liu
authors.forename: Qixing
authors.initials: Q
authors.lastname: Zhou
authors.forename: Xiujie
authors.initials: X
authors.lastname: Xie
authors.forename: Dasong
authors.initials: D
authors.lastname: Lin
authors.forename: Luxi
authors.initials: L
authors.lastname: Dong
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000008:administration & dosage / Q000633:toxicity*; D002374:Catalase / Q000187:drug effects / Q000378:metabolism; D020552:Comet Assay / Q000379:methods; D004249:DNA Damage / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000379:methods; D009835:Oligochaeta / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D009195:Peroxidase / Q000187:drug effects / Q000378:metabolism; D012989:Soil Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D013482:Superoxide Dismutase / Q000187:drug effects / Q000378:metabolism; D014050:Toluene / Q000008:administration & dosage / Q000633:toxicity*; D014992:Xylenes / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D001555:Benzene Derivatives; D012989:Soil Pollutants; D014992:Xylenes; D014050:Toluene; C121048:guaiacol peroxidase; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; C004912:ethylbenzene