Histopathological Changes in Fish Exposed to Organophosphate Insecticides

Abstract

The increasing use of organophosphate insecticides in agricultural practices poses a serious threat to aquatic ecosystems, particularly freshwater fish that are often exposed to these toxicants through runoff and leaching. This study was undertaken to assess the histopathological effects of two commonly used organophosphates, chlorpyrifos and monocrotophos, on freshwater fish species under sub-lethal exposure conditions. Fish were exposed to environmentally relevant concentrations over a 28-day period, and histological examinations were conducted on critical organs such as the gills, liver, and kidneys. The findings revealed pronounced structural damage in all three organs. Gills exhibited epithelial lifting, lamellar fusion, and hemorrhage; liver samples showed hepatocellular vacuolization, necrosis, and vascular congestion; and kidneys displayed tubular degeneration and glomerular deformities. These pathological alterations indicate compromised respiratory, detoxification, and excretory functions in the fish, even under non-lethal exposure levels. The severity of tissue damage was more pronounced in fish exposed to monocrotophos compared to chlorpyrifos, suggesting higher toxicity. The results emphasize the utility of histopathological biomarkers as sensitive indicators of aquatic pollution and underline the urgent need for sustainable pesticide use practices. This research contributes to a better understanding of the chronic effects of organophosphate pesticides on aquatic fauna and supports their consideration in environmental monitoring and regulatory frameworks.