Organochlorine pesticide residue levels in river water and sediment from cocoa-producing areas of Ondo State central senatorial district, Nigeria

The health risks posed by organochlorine compounds to the total environment have continued to elicit concern among researchers worldwide. Hence, this study focused on investigating the varieties and concentrations of organochlorine pesticide residues in river water and sediments from cocoa-producing areas in Ondo Central Senatorial District of Nigeria. The organochlorine pesticides extracted with a mixture of organic solvents were quantified by Gas Chromatography – Mass Spectrometry (GC-MS). Aldrin, dieldrin, lindane, heptachlor epoxide, α-endosulfan, β- endosulfan, β- benzene hexachloride, and δ-benzene hexachloride were detected in the samples, with endosulfan isomers occurring most frequently. The findings provide no evidence of accumulation of organochlorine compounds in the river benthics but the total organochlorine compounds measured gave a significant positive correlation (p < 0.05) with the organic and clayey matter contents of the river sediments, suggesting that these components of river sediments play important role in retaining organochlorine compounds. This study constitutes an initial investigation of the levels of organochlorine compounds in the area and will thus serve as a reference for future investigations and environmental performance measurements.