DNA damage and oxidative stress induced by endosulfan exposure in zebrafish (Danio rerio)

Endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzo-dioxathiepin-3-oxide), an organochlorine pesticide, is prevalently used all around the world. It is considered to be a new candidate for the persistent organic pollutants group. Endosulfan residues in the environment may cause serious damage to ecosystems, especially in aquatic environments. The present study was conducted to investigate the effect of endosulfan on antioxidant enzymes [catalase (CAT) and superoxide dismutase (SOD)], reactive oxygen species (ROS) generation and DNA damage in zebrafish. Male and female zebrafish were separated and exposed to a control solution and four concentrations of endosulfan (0.01, 0.1, 1, and 10 μg L⁻¹) and were sampled after 7, 14, 21, and 28 days. It is noteworthy that the present research explored the correlation among the three indicators induced by endosulfan. Low endosulfan concentrations (0.01 μg L⁻¹) induced a slight increase of SOD and CAT activity, which kept ROS in a stable level. High endosulfan concentration (10 μg L⁻¹) induced excessive ROS production which exceeded the capacity of the cellular antioxidants and exhausted the enzyme including CAT and SOD. The DNA damage of zebrafish was evaluated by single-cell gel electrophoresis and was enhanced with increasing endosulfan concentration. In conclusion, the present study showed that endosulfan (0.01-10 μg L⁻¹) has toxic effects on zebrafish.