Assessment of organochlorine pesticide residues in agricultural soils of southern Nigeria and analysis of potential health risks.

Abstract

The use of pesticides in commercial farms can lead to exposure among various vulnerable groups. This study assessed the distribution, human health risks, and origins of 13 targeted organochlorine pesticides (OCPs) in soil samples from commercial farms in Southern Nigeria. Following a questionnaire survey on pesticide usage, soil samples were subjected to Soxhlet extraction and analyzed using gas chromatography-mass spectrometry. Results indicated that 31.6 % of farmers did not use personal protective equipment, and only 37.6 % had received training on safe pesticide application. While pyrethroids and organophosphates were commonly used, organochlorines were rarely applied. The detected levels of OCPs in the agricultural zones ranged from below detection limit (BDL) to 18.35 ± 13.83 µg/kg and were generally within the minimum risk level (MRL), except for α-HCH and β-HCH in Oron and Etinan zones. The estimated non-carcinogenic risk s from detected OCPs were insignificant at the time of the study, as the calculated Hazard Indexes (HIs) and Hazard Quotients (HQs) for ingestion, dermal absorption, and inhalation were all less than 1, indicating generally low risks. The carcinogenic risk assessment showed that the Incremental Lifetime Cancer Risk (ILCR) values ranged from 10^-10 to 10^-4, indicating a very low to low risk level according to the classification by the United States Agency for Toxic Substances and Disease Registry (US ATSDR). Source apportionment suggested that most OCP congeners were of historical origin, with only a few indicating recent use. In conclusion, organochlorine pesticide residues in the studied farms posed minimal health risks, with most originating from historical rather than recent use.