Oxidative Stress and DNA Damage Induced by DEP Exposure in Earthworms

Abstract

Diethyl phthalate (DEP) is a plastic additive that entered the soil environment due to the extensive use of plastic products. However, its toxicity to soil animals and the associated toxicity mechanism were not completely understood. Eisenia foetida was selected as the research object and exposed to simulated contaminated soil with different concentrations of DEP. Antioxidant enzyme activity, reactive oxygen species (ROS) content, Glutathione-S-Transferase (GST) activity, Malondialdehyde (MDA) content and amount of DNA damage in the earthworms were used as evaluation parameters for the study. The results showed that under DEP stress, the activities of antioxidant enzymes, GST and ROS in earthworms changed and resulted in gene damage. Under the stress of 0.1-50 mg·kg-1 DEP exposure during the 28 d experiment, the level of ROS increased and there was a "dose-effect" relationship. Excessive ROS gave rise to an increase of MDA content in the body from lipid peroxidation. Under the combined action of ROS and MDA, DNA in the body cavity of earthworm was damaged and there was also a "dose-effect" relationship between the degree of damage and the concentration of DEP. In summary, DEP may cause a certain degree of damage to organisms, with damage to the DNA of earthworms representing fairly strong eco-toxicological effects. Therefore, adequate attention should be paid to DEP disposal.