Dose-dependent hepatorenal toxicity of polystyrene microplastics in BALB/c mice

Microplastics have emerged as pervasive environmental contaminants with increasing concern regarding their potential adverse effects on mammalian health. However, comprehensive evaluations of the dose-related hepatorenal toxicity of polystyrene microplastics (PS-MPs) remain limited. This study investigated the effects of oral exposure to PS-MPs on hepatic and renal function in BALB/c mice. Animals were randomly assigned to four groups (n = 10/group) and orally administered 0 (control), 10, 20, or 30 mg PS-MPs/kg body weight/day for 28 consecutive days. Hepatorenal toxicity was evaluated using serum biochemical biomarkers, histopathological examination, semi-quantitative lesion scoring, and Pearson’s correlation analysis. PS-MP exposure produced dose-related increases in serum alanine aminotransferase (ALT; P = 0.0247), aspartate aminotransferase (AST; P = 0.0192), alkaline phosphatase (ALP; P = 0.0044), bilirubin ( P = 0.0045), creatinine ( P = 0.0029), and urea ( P = 0.0006), with generally higher values observed at increasing PS-MPs doses indicating hepatic and renal dysfunction. Histopathological assessment demonstrated increasing severity of hepatic inflammatory infiltration, hepatocellular degeneration, necrosis, sinusoidal dilatation, and renal tubular epithelial degeneration/necrosis with increasing PS-MP dose. Semi-quantitative histopathological scores differed significantly among groups (Kruskal–Wallis, P < 0.0001), with the greatest lesion severity observed in the high-dose group. Pearson’s correlation analysis revealed significant positive correlations between creatinine and urea ( r = 0.7628, P < 0.0001) and between ALP and bilirubin ( r = 0.5229, P = 0.0087), supporting the biochemical evidence of renal and hepatobiliary dysfunction. In conclusion, oral exposure to PS-MPs was associated with hepatorenal toxicity,characterized by biochemical alterations and increasing histopathological injury with increasing exposure dose. These findings provide experimental evidence of the adverse effects of PS-MPs on mammalian liver and kidney function and contribute to a better understanding of the potential health risks associated with chronic microplastic exposure.