Enantioselective Oxidative Stress and DNA Damage Induced by - and -metolachlor on the Earthworm .

Metolachlor is a widely used chiral herbicide. However, information on its enantioselective toxicity to earthworms, an important soil organism, remains limited. Herein, the effects of - and -metolachlor on oxidative stress and DNA damage in were investigated and compared. Moreover, the degradation of both herbicides in the soil was also determined. The results showed that reactive oxygen species (ROS) in were more easily induced by -metolachlor than -metolachlor at a higher concentration (above 16 µg/g). Similarly, the effects of -metolachlor on superoxide dismutase (SOD) activity and DNA damage in were more significant than those of -metolachlor at the same exposure concentration and time. - and -metolachlor did not result in severe lipid peroxidation. The toxic effects of both herbicides on gradually decreased after 7 days as the exposure was prolonged. At the same concentration, -metolachlor degrades faster than -metolachlor. These results suggest that -metolachlor has a greater effect on than -metolachlor, providing a significant reference for the rational use of metolachlor.