Risk Assessment of Heavy Metal Levels in Vegetables Grown in the Vicinity of Local Mining Areas in Odu, Dekina Local Government Area, Kogi State, Nigeria

Abstract

This study assessed the concentrations of selected heavy metals and the associated non-carcinogenic health risk in vegetables cultivated in the vicinity of the Odu local mining area in Dekina Local Government Area, Kogi State, Nigeria. Five vegetable species—Amaranthus hybridus, Abelmoschus esculentus, Lycopersicon esculentum, Capsicum frutescens, and Solanum incanum—were collected from mining-affected locations. The samples were dried, pulverized, digested by a wet-acid procedure using aqua regia, and analyzed for cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and arsenic (As) using atomic absorption spectrophotometry. The reported concentrations of Cd, Cr, Cu, Ni, and Pb ranged from 0.01–0.05, 0.01–0.11, 0.04–0.09, 0.04–0.09, and 0.03–0.21 mg/kg, respectively, while As was below the instrumental detection limit in all samples. Comparison with the permissible limits reported in the original study indicates that Cd and Pb warrant particular attention, while Ni exceeded some of the cited guideline values in three vegetable samples. The calculated target hazard quotients (THQs) and summed health risk indices (HRIs) were below 1 for the reported exposure scenario. These findings indicate that, although the calculated non-carcinogenic risk was below the conventional threshold, continued consumption of vegetables cultivated near mining areas may warrant precaution because heavy metals can persist in environmental media and enter the food chain. Regular monitoring, farmer education, and cultivation of vegetables away from potentially contaminated mining-affected soils are recommended.