Lead and endosulfan toxicity: individual and synergistic effects on <i>Labeo rohita</i> health biomarkers, tissue accumulation, and genotoxicity

This study investigated the individual and combined toxicological effects of lead (Pb) and endosulfan on <i>Labeo rohita</i> fingerlings following a 28-day sublethal exposure. Seven experimental groups were established, including control, low and high concentrations of Pb and endosulfan, and their respective combinations. Hematological, biochemical, neurotoxic, tissue bioaccumulation, and genotoxic biomarkers were assessed. Results revealed significant hematological disturbances characterized by reductions in red blood cell count, hemoglobin, and hematocrit, alongside elevated white blood cell counts. Biochemical analyses showed hyperglycemia, hypoproteinemia, dyslipidemia, increased creatinine and urea levels, and marked elevation of hepatic enzymes (ALT, AST, ALP). Neurotoxicity was evident through significant inhibition of acetylcholinesterase activity, with the greatest suppression observed under combined high-dose exposure. Tissue analysis demonstrated substantial accumulation of Pb and endosulfan in gill, liver, and kidney tissues, with co-exposure resulting in up to 1.7-fold higher accumulation than individual treatments. Genotoxicity assessment using the comet assay revealed pronounced DNA damage, with damaged erythrocytes exceeding 65% and a threefold increase in genetic damage index in the combined high-dose group. Two-way ANOVA confirmed significant Pb × endosulfan interactions, highlighting synergistic toxicity. Overall, the findings underscore the heightened ecological and food safety risks associated with concurrent heavy metal and pesticide contamination in freshwater ecosystems.