Seasonal dynamics and ecological risks of organochlorine pesticides in Kafrelsheikh-Egypt: Implications for aquatic ecosystems and public health

Kafrelsheikh, situated in the middle of the Nile Delta, significantly contributes to Egypt's aquaculture and agriculture sectors. However, the local use of organochlorine pesticides (OCPs) in agriculture is often a source of OCP residues in associated drainage waters, which may threaten aquatic ecosystems. These pesticides persist in local water bodies, jeopardizing aquatic ecosystems and potentially impacting human health. This comprehensive study assessed the seasonal variations of 17 OCPs in both water sources and Nile tilapia across eight fish farming locations in Kafrelsheikh. Using gas chromatography coupled with mass spectrometry (GC-MS), we detected OCP concentrations in water that varied seasonally where winter recorded the highest levels at 22.5 ng/mL and, summer showed the lowest levels at 6.2 ng/mL. Despite water samples occasionally showing risk quotients (RQs) greater than 1, indicating a potential threat to aquatic life, the OCP levels in Nile tilapia were sufficiently low, with target hazard quotients (THQ) below 1, suggesting no significant risk for human consumption. The research highlights a pressing need for regular environmental monitoring and stricter regulatory control over pesticide use to protect aquatic life and ensure the safety of aquaculture products. These findings provide a critical basis for policy-making, aimed at balancing agricultural productivity with environmental sustainability in regions heavily dependent on both.