Toxicity Impact of Polyethylene Microplastics on Biochemical Parameters and Oxidative Stress in Benni Fish (Barbus sharpeyi)

Abstract

This study evaluated the effects of polyethylene microplastics (PE-MPs) on the biochemical and oxidative stress parameters in Benni fish (Barbus sharpeyi). Fingerlings (average weight: 10 ± 2 g, length: 6 ± 1 cm) were exposed to PE-MP concentrations of 0, 200, 400, 800, and 1600 mg/L for 21 days under controlled laboratory conditions. Biochemical analyses revealed significant increases in plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP) activities, particularly at higher PE-MP concentrations. A significant increase was observed in albumin levels in fish plasma after exposure to 400, 800, and 1600 mg/L of PE-MPs. Cholesterol levels in fish plasma exposed to 400, 800, and 1600 mg/L of PE-MPs were significantly higher than in the control group. Elevated levels of total protein, albumin, cholesterol, triglycerides, and creatinine were also observed, with minimal changes in globulin levels. Oxidative stress markers, including superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT), were significantly increased in the hepatocytes, while total antioxidant capacity (TAC) and thiol levels decreased. Malondialdehyde (MDA) levels were significantly elevated, indicating lipid peroxidation and oxidative damage. The change in the integrated biomarker response (IBR) index was dose-dependent, and the highest IBR stress was observed at 1600 mg/L PE-MPs. Significant changes in oxidative stress biomarkers and blood biochemical parameters of Barbus sharpeyi indicated the potentially toxic effects of MPs in aquatic environments. These results provided clear evidence of the hepatotoxic, nephrotoxic, and oxidative stress effects of PE-MPs.