A study on persistent organochlorine pesticide residues in fish tissues and water from an agricultural fish pond

Organochlorine pesticides (OCPs), (α - BHC, β - BHC, γ - BHC, Heptachlor, Aldrin, Chlordane, p, p - DDE, o, p - DDD, p, p - DDD, Dieldrin, Endrin, Endosulfan and p, p - DDT) were determined in water and fish samples from the fish pond of Oke-Osun Farm Settlement, Osogbo, Nigeria that receive runoffs from agricultural lands. The aim of the study was to investigate the pollution status of the pond water and fish samples. Qualitative and quantitative analysis of the OCPs after clean-up on silica gel adsorbent were carried out using Gas Chromatography equipped with Electron Capture Detector (GC-ECD). The results showed higher levels of OCPs in the pond water during the rainy season than during the dry season. Higher levels of OCPs were found in the fish samples in the dry season than during the rainy season. Significant positive correlations at p ≤ 0.05 level were observed for β - BHC and aldrin, chlordane, p, p - DDE, dieldrin and endrin; γ - BHC and heptachlor, p, p - DDE, dieldrin and endrin; heptachlor and p, p - DDD, dieldrin and endrin; heptachlor and p, p - DDD, dieldrin and endrin; p, p - DDE and dieldrin and endrin; and dieldrin and endrin. The mean seasonal levels of OCPs in the fish were higher, in most cases, than the recommended WHO Maximum Residue Levels (MRLs) in food items and should give cause for concern. Due to possible toxicity and bioaccumulation tendency of the OCPs by the predators higher in the food chain, the levels of OCPs detected in the fish samples could be a source of future health problems. The OCPs detected are consistent with the agricultural activities of the study area due to pesticide usage.