Determination of Organ chlorine Pesticide Residues in Water, Sediment, and Fish from the Gilgel Gibe Reservoir and Its Tributaries, And Associated Health Risk Assessment, Jimma, Ethiopia

Abstract

In this study, the levels of Organochlorine pesticides (OCPs) residues in water, sediment, and fish samples collected from the Gilgel Gibe I Dam and its tributaries were investigated, along with the associated health risks. Prior to GC-MS analysis, Soxhlet extraction was used to extract OCPs from sediment and fish, while homogeneous liquid-liquid microextraction (HLLME) was used for water samples. The findings revealed that from the OCPs, gamma hexachlorocyclohexanes (γ HCH) was the most prevalent in the reservoir and tributaries water samples, especially in Yadi River (YR) (10.97 µg/L) and Nada Guda River (NGR) (7.04 µg/L), with lower levels in their River mouths and reservoirs. Para, para dichlorodiphenyltrichloroethane (p’, p’-DDT) and its metabolites dichlorodiphenyldichloroethylene (p’, p’-DDE), dichlorodiphenyldichloroethane (p’, p’-DDD) were widely detected across sites, ranging from 5.55 µg/L to 11.70 µg/L. High pesticide levels, particularly alpha hexachlorocyclohexanes (α-HCH), γ-HCH, heptachlor (HC), and aldrin, were found in Nadi River Sediment (NRS), Yadi River Sediment (YRS), and Nada Guda River Sediment (NGRS), with concentrations up to 71.93 µg/kg. Beta endosulfan (β-ES) and dieldrin were detected at lower levels. Sediments from Nada Qala River and River mouths sites showed lower pesticide concentrations. African catfish from Unkure had heptachlor epoxide (HCE) levels (225.22 µg/kg) exceeding the maximum residue limit (MRL) of 200 µg/kg. Other OCPs like α HCH, γ-HCH, HC, and p’, p’-DDT were detected in African catfish and Nile tilapia but remained below MRLs. However, the Health Risk Index (HRI) values for both fish species remained below the critical value of 1, indicating no significant health risks from consumption.