Co-exposure to polystyrene microplastics and perfluorooctanoic acid can exacerbate lipid metabolism disorders and liver damage in adult zebrafish

Microplastics (MPs) and perfluorooctanoic acid (PFOA) are common emerging environmental contaminants in aquatic environments, and their ecological risks have become a research focus. Although they coexist widely in aquatic environments, the combined toxicity of polystyrene microplastics (PS-MPs) and PFOA to aquatic organisms remains unclear. This study investigated the individual and combined toxicity of PS-MPs and PFOA to zebrafish after 28 days of exposure. The results showed that ingestion of PS-MPs and PFOA induced intestinal and liver tissue damage, alterations in oxidative stress, and lipid index in zebrafish. The breakdown of the intestinal barrier will further lead to the increase of lipopolysaccharide in the blood. Notably, combined exposure to PS-MPs and PFOA exerted greater adverse effects than exposure to each contaminant individually. Additionally, exposure to PS-MPs and PFOA significantly disrupted the homeostasis of the intestinal microbiota, and the relative abundances of Proteobacteria and Actinobacteria significantly increased. Transcriptomic analysis further revealed that exposure to PS-MPs and PFOA would lead to the upregulation of genes related to lipid metabolism in zebrafish and alterations in pathways such as glycerolipid metabolism, fat digestion and absorption, and peroxisome proliferator-activated receptor signaling. In conclusion, this study demonstrates that combined exposure to PS-MPs and PFOA exacerbates liver and intestinal damage in zebrafish, disrupts lipid homeostasis, and may contribute to the development of nonalcoholic fatty liver disease. This study has enhanced our understanding of the environmental health risks from the coexistence of MPs and PFOA, and has reference value for formulating complex pollution control standards.