Toxicological evaluation and metabolic profiling of earthworms (Eisenia fetida) after exposure to microplastics and acetochlor

In recent years, microplastic (MPs) and pesticide pollution have become prominent issues in the field of soil pollution. This research endeavored to assess the impact of ultraviolet radiation (UV) on the characteristics of microplastics, as well as investigating the toxicological effect on earthworms (Eisenia fetida) when subjected to the dual stressors of microplastics and acetochlor (ACT). This research found that microplastics aged under UV were more prone to wear and tear in the environment, and produced more oxygen-containing functional groups. Chronic exposure experiments were conducted on ACT and aged-MPs. The results revealed that aged-MPs and ACT inhibited earthworm growth, induced oxidative stress, and caused damage to both the body cavity muscles and the intestinal lumen. Compared with individual exposure, combined exposure increased the oxidative products (superoxide dismutase (SOD) and catalase (CAT)) and altered the expression levels of related genes (TCTP and Hsp70) significantly. PE inflicted more significant harm to the earthworm intestinal tissue compared to PBAT. By 1H-NMR metabolomics, the investigation delved into the repercussions of PE and ACT on the metabolic pathways of earthworms. Exposure to ACT and PE can disrupt the stability of intestinal membranes stability, amino acid metabolism, neuronal function, oxidative stress and energy metabolism. Overall, the research revealed that combined exposure of MPs and ACT exacerbated the negative effects on earthworms significantly, and contributed valuable insights to environmental risk assessment of the combined toxicity of microplastics and pesticides.