Pesticide accumulation in tissues of cultured Oreochromis niloticus and Mugil cephalus: effects on biochemical biomarkers and associated human health risks

Abstract

Background

Egypt's food security depends heavily on aquaculture, however fish farmed on farms that receive agricultural drainage water may be subjected to pesticide pollution. Such contamination can impair fish health, alter physiological functions, and pose potential risks to consumers. This study investigated the occurrence and distribution of pesticide residues in water and in the gill, liver, and muscle tissues of two economically important species, Oreochromis niloticus and Mugil cephalus, collected from four fish farms that differ in their water sources in Fayoum Governorate, Egypt. The control farm was irrigated with fresh water, while the other farms were irrigated with agricultural drainage water. It also evaluated the biochemical and stress-related responses in fish and assessed potential risks associated with human consumption.

Results

Farms supplied with drainage water exhibited higher salinity and nutrient pollution compared to the freshwater control farm. Multiple classes of pesticides, including organochlorine insecticides, pyrethroid insecticides, and herbicides, were detected in both water and fish tissues, with the highest concentrations found at the El-Bats and Dayer El-Berka farms. Pesticide accumulation varied by species and organ: O. niloticus accumulated the highest levels in the liver, whereas M. cephalus accumulated more in the gills. Fish from polluted farms showed reduced activities of the liver enzymes aspartate aminotransferase and alanine aminotransferase, alongside increased concentrations of triglycerides, cholesterol, and total lipids in muscle tissue. Oxidative and cellular stress markers, including malondialdehyde and caspase-12, were elevated in all examined tissues, while catalase activity was reduced.

Conclusions

Fish raised in agriculture drainage-fed aquaculture systems showed clear evidence of pesticide exposure, organ-specific accumulation patterns, and associated biochemical and stress responses. Despite exceedances of regulatory residue limits for some compounds, the overall dietary risk to consumers was found to be low based on estimated intake calculations. Nevertheless, the high prevalence of pesticide mixtures in water and fish highlights the need for continuous monitoring and management of agricultural runoff to maintain aquaculture productivity and ensure safe consumption.