Human Health Risk Associated with Dietary and Non-Dietary Intake of Organochlorine Pesticide Residues from Rice Fields in Edo State Nigeria

Abstract

The levels, distribution patterns, ecological risk and human health risk of fourteen organochlorine pesticides in surface water, sediment, and fish (Tilapia zilli and Clarias gariepinus) collected from a massive rice field in Illushi, were monitored. Samples obtained were extracted and analyzed using gas chromatography equipped with electron capture detector while risk assessment was carried out using standard models (risk quotient and Chronic daily intake). Pesticide concentration in water samples ranged from ND to 1.65 µg/l, while the concentration of pesticide residues in sediment, C. gariepinus, and T. zilli ranged from ND to 8.45 µg/kg dw, 0.03 to 1.57 µg/kg/ww, and 0.03 to 0.85 µg/kg/ww, respectively. There was a clear dominance of the organochlorine; Hexachlorocyclohexane (α-HCH, γ-HCH, β-HCH) in all matrices. Risk quotient estimates for heptachlor, heptachlor epoxide, aldrin, dieldrin, DDT, endosulfan I, endosulfan II, and endosulfan aldehyde showed risk to aquatic organisms under extreme conditions. Health risk estimations showed that there is a potential risk to humans exposed to contaminated water, sediment, and fishes through ingestion, inhalation, and dermal routes of exposures. Cumulative hazard quotient estimated for pesticide mixtures in each matrix further confirmed that there was potential risk to human health especially children. Furthermore, the risk of non-carcinogenic effects followed the following sequence; biota > sediment > water. This study presents evidence of the multiple contamination of water, sediment, and biota from the Illushi River Basin which would possibly lead to non-cancer effects in humans especially children when exposed. Therefore, water bodies draining agricultural farmlands should be monitored regularly to prevent the contamination of the aquatic environment by toxic and banned pesticides, while efforts should be intensified to regulate the sales, application, and disposal of pesticide products in Nigeria.