Assessment of Pesticide Contamination Level of Fish and Human Health Risks in Lake Ziway, Ethiopia

Lake Ziway, located in the Ethiopian Rift Valley, faces significant environmental pressure due to intensive agricultural and floriculture practices. Pesticides are heavily utilized to boost production. This study examined the concentrations, bioaccumulation, and health risks associated with 22 selected pesticides in four fish species: Oreochromis niloticus, Cyprinus carpio, Carassius carrasius , and Clarias gariepinus . A total of 48 fish, grouped by size into three sets for each species, were sourced from local fisheries and analyzed in duplicate. The dorsal muscle samples were extracted using a speed extractor, purified with florisil, and quantified using gas chromatography coupled with mass spectrometry (GC-MS/MS). Most compounds showed mean recoveries between 60% and 120%, except for dieldrin (51.33%) and bendiocarb (121.86%). Detection limits ranged from 0.01 to 2.6 µg kg ^− 1 . Positive pesticide residues, including Σ HCH, Σ DDTs, HCB, Σ heptachlor, chlorpyrifos, propoxur, and diazinon, were detected at concentrations between 0.010 and 66.44 µg kg ^− 1 . However, levels of β-HCH, γ-HCH, aldrin, dieldrin, endosulfan I, endosulfan sulfate, bendiocarb, profenofos, chlordane-trans, chlordane-cis, methoxychlor, and chlorpyrifos-methyl were below the detection limit. DDTs were the most prevalent contaminants, with concentrations ranging from 5.08 to 213.61 µg kg ^− 1 , likely due to historical contamination from past practice. Prolonged consumption of pesticide-contaminated fish poses carcinogenic risks, highlighting the need for stringent enforcement of pesticide regulations.