From plastic to pathophysiology: polyethylene (PE) and polyvinyl chloride (PVC) microplastics disrupt fish blood, metabolism, and growth.

Abstract

Rising global plastic use has led to widespread synthetic polymer pollution in aquatic ecosystems, threatening aquatic life. The combined toxicity of prevalent plastics like polyethylene (PE) and polyvinyl chloride (PVC) under realistic conditions remains largely unexplored. This study provides the first evaluation of the impact of environmentally relevant concentrations (0.5 mg/L) of PE- and PVC-MPs, individually and in combination, on Channa punctatus over a 21-day exposure period, uniquely revealing the enhanced toxicity of combined MPs through an integrated assessment of hematological, biochemical, genotoxic, and growth biomarkers. Hematological assessments revealed declines in hemoglobin and erythrocyte count, alongside increments in leukocytes, suggesting anemia and immune activation. Biochemical analyses revealed significant (p < 0.05) physiological stress, as reflected by elevated SGOT, SGPT, ALP, LDH, creatinine, blood urea nitrogen, glucose, cholesterol, triglycerides, and disturbances in protein profiles, including albumin, globulin, and the A/G ratio. Erythrocytic nuclear abnormalities such as micronuclei, nuclear bud, binucleated cells, blebbed, tear-drop, kidney-shaped and notched nuclei reflected genotoxic and cytotoxic stress. Growth performance was markedly impaired, with reductions in weight gain, %weight gain, specific growth rate, feed intake ratio and condition factor. Notably, the co-exposed group exhibited the most severe alterations across all parameters, underscoring the mixture toxicity of combined MPs. Pearson correlation analysis further established strong associations among all studied parameters, strengthening the diagnostic potential of these biomarkers for MPs toxicity in sentinel fish species. These findings sound an urgent call to recognize and mitigate the silent yet combined threat of mixed microplastic pollution in freshwater ecosystems.