Organochlorine pesticide residues in farmed fish in Machakos and Kiambu counties, Kenya

Abstract

This study was conducted to evaluate occurrence of organochlorine pesticide residues in Oreochromis niloticus fish reared by aquaculture in Kiambu and Machakos Counties. A total of 213 fish organ samples were analyzed for organochlorine pesticide residues from Kiambu and Machakos Counties in Kenya using gas–liquid chromatography. Overall, betahexachlorocyclohexane (BHC) group, the cyclodiens, aldrin, heptachlor, dieldrin, endrin and the Dichlodiphenyltrichloroethane (DDT) group of compounds were detected in fish samples. p,p′-DDT and its metabolite p,p′-DDD were detected in the muscle, liver and gonad and their concentration ranged between not detectable (ND) to 0.916 μg kg−1 for p,p′-DDT and ND to 1.684 μg kg−1 for p,p′-DDD. Brain had the highest concentration of DDT metabolites o, p′-DDT (2.098 ± 4.097 μg kg−1) and p′ p-DDD (1.684 ± 3.666 μg kg−1). Organochlorine pesticide residues were generally higher in Kiambu County compared to Machakos County but there was no significant difference. The residue levels of organochlorines in all fish samples analyzed were lower than the benchmark levels set by FAO, FDA, and NAS/NAE.