Effects of micro-plastic particles on paraquat toxicity to common carp (Cyprinus carpio): biochemical changes

In this study, we investigated the possible effects of paraquat and micro-plastics on blood biochemical parameters in common carp (Cyprinus carpio). We exposed C. carpio for 21 days to sublethal concentrations of paraquat (0.2 and 0.4 mg L-1) and micro-plastics (1 and 2 mg L-1), alone or in combination. Blood biochemical analysis indicated that exposure to 0.4 mg L-1 paraquat and mixture of paraquat and micro-plastics was followed by an increase in aspartate aminotransferase (AST), alkaline phosphatase (ALP), and creatine phosphokinase (CPK) activities and glucose levels. The activity of ALP and CPK showed a significant increase in fish treated with 2 mg L-1 micro-plastics. No significant changes were observed in glucose level, AST, ALT, and LDH activities in fish exposed to micro-plastics. Exposure to paraquat and/or micro-plastics resulted in a significant decrease in total protein, globulin, cholesterol, and triglyceride levels and gamma-glutamyl transferase activity. When fish were exposed to paraquat or paraquat and micro-plastics, alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) activities increased significantly compared to the control group. Treating fishes with a mixture of paraquat and 2 mg L-1 micro-plastics caused a significant increase in albumin levels. However, a significant decrease in the albumin level was observed after exposure to paraquat or micro-plastics. Creatinine levels increased after exposure to paraquat and/or micro-plastics. The results indicate that increased doses of micro-plastics in water significantly increased toxic effects of paraquat in fish. Finally, these data support the hypothesis that changes in blood biochemical parameters were induced by exposure to paraquat and/or micro-plastics.