Evaluating pesticide-induced toxicity in Cyprinus carpio using hemato-biochemical biomarkers.

Abstract

The increasing use of pesticides threatens aquatic ecosystems. This study evaluated the toxic effects of carbosulfan, pyriproxyfen, thiamethoxam, and their mixture on the hemato-biochemical profile of Cyprinus carpio over a 30-day exposure period. The 96 h LC₅₀ values, determined via probit analysis, were 5.49 µg/L for carbosulfan, 8.91 µg/L for pyriproxyfen, and 11.48 µg/L for thiamethoxam. A total of 150 fish were divided into five groups (G1, G2, G3, G4, and G5), with 50 specimens in each group, and each treatment was replicated three times. Group G1 served as the control, while groups G2-G5 were exposed to 2.74 µg/L carbosulfan, 4.45 µg/L pyriproxyfen, 5.74 µg/L thiamethoxam, and a mixture of all three pesticides, respectively. The concentrations used correspond to 50% of each pesticide's 96 h LC₅₀ value. Blood samples were collected on the 15^th and 30^th days from both control and exposed groups for hemato-biochemical assessment. Results showed a significant (p < 0.05) decline in red blood cells, hemoglobin, hematocrit, and platelets, along with increased white blood cells across all treated groups. Mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration in pyriproxyfen- and thiamethoxam-treated groups increased insignificantly on day 15, but significantly (p < 0.05) on day 30 compared with controls. Pesticide exposure also resulted in a significant (p < 0.05) reduction in serum total protein, triglycerides, sodium, potassium, calcium, chloride, and thyroid hormones (T₃ and T₄). Conversely, glucose, cholesterol, urea, creatinine, phosphorus, iron, thyroid-stimulating hormone, cortisol, and liver enzymes aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and lactate dehydrogenase showed significant (p < 0.05) increases. The toxicity ranking was carbosulfan > mixture > pyriproxyfen > thiamethoxam. Our findings highlight the adverse effects of the combined use of the selected pesticides and support the efficacy of the multi-biomarker approach in elucidating the toxicological mechanisms induced by pesticide exposure.