SEASONAL OCCURRENCE AND ASSOCIATED RISK OF ORGANOCHLORINE PESTICIDES IN SOME SELECTED DUMPSITES SOIL IN OROGUN, DELTA STATE, NIGERIA

The seasonal occurrence and associated risk of organochlorine pesticides (OCPs) in soils from selected dumpsites in Orogun, Delta State, Nigeria, were assessed to evaluate potential risks to human health. Soil samples were collected from three layers (top, sub, and bottom) at various dumpsites using excavation methods. The samples were labeled and transported to the laboratory for analysis. OCPs were extracted and analyzed using gas chromatography with flame ionization detection after solvent extraction. The concentrations of the Ʃ20 OCPs in the soils ranged from 0.74 to 7.29 ng/g during the dry season and from 0.09 to 9.47 ng/g during the wet season. The highest concentrations were found in D23 (dry season) and D2 (wet season), while the lowest were in D21 (dry season) and D3 (wet season). Significant spatial and seasonal variations (p < 0.05) in OCP concentrations were observed, influenced by soil physicochemical properties, OCP sources, and pesticide degradation rates. The hazard index (HI) values for infants were seven times higher than for adults, indicating greater exposure risks for infants. HI values were below 1 for both seasons, except in specific sites (D1, D2, D10, D13, D16, D20, and D26) during the dry season, and (D1, D2, D10, D11, D13, D14, and D16) during the wet season, suggesting health risks in these locations. The total carcinogenic risk (TCR) for infants was 13 times higher than for adults, reflecting a higher exposure risk for infants. TCR values ranged from 9.17 x 10⁻⁴ to 1.25 x 10⁻⁷ in the dry season and 7.27 x 10⁻⁶ to 1.55 x 10⁻⁴ in the wet season, staying below the acceptable limit of 1 x 10⁻⁴, indicating no significant carcinogenic risk for both infants and adults.