K. OJEAGA

Mining and quarrying activities significantly contribute to environmental degradation and heavy metal contamination in Nigeria. The mechanical extraction of mineral resources leads to extensive landscape degradation, soil contamination, and increased human exposure to toxic elements. The study evaluated the carcinogenic and non-carcinogenic health risks associated with heavy metal contamination in soils surrounding quarrying communities in Ikpeshi and its environs, Edo State, Nigeria; assessing the extent of pollution, the ecological risk posed by heavy metals, and their potential human health implications. Soil samples were collected from four different locations at varying distances (0m, 100m, 200m) from active quarrying sites. Heavy metal concentrations were analyzed using Atomic Absorption Spectrophotometry (AAS). Pollution indices, including the Contamination Factor (Cf), Pollution Load Index (PLI), and Geo-accumulation Index (Igeo), were used to assess contamination levels. Human health risk assessments followed the United States Environmental Protection Agency (USEPA) guidelines, computing the Average Daily Dose (ADD), Hazard Quotient (HQ), and Total Carcinogenic Risk (TCR) for ingestion, dermal contact, and inhalation exposure. The findings revealed that iron (Fe) had the highest concentration, with a mean value of 412.884 mg/kg. Followed by zinc (Zn) with a mean concentration of 40.652 mg/kg. Copper (Cu) (28.348 mg/kg). Lead (Pb) (1.105–5.755 mg/kg), cadmium (Cd) (0.5–2.01 mg/kg), nickel (Ni) (6.86–18.41 mg/kg), and chromium (Cr) (5.16–12.075 mg/kg) were also detected, with Cd and Ni exceeding permissible limits. The Pollution Load Index (PLI > 1) and Geo-accumulation Index (Igeo > 1) indicated moderate to heavy contamination in soils near quarry sites. The non-carcinogenic risk assessment showed that children had a higher cumulative Hazard Index (HI = 0.13745) than adults (HI = 0.02417), suggesting increased vulnerability. For dermal exposure, cobalt (Co) had the highest HQ (0.03526) in children, indicating potential health risks. Carcinogenic risk assessment showed that nickel (Ni) (TCR = 2.14 × 10⁻⁴ for children, 3.10 × 10⁻⁵ for adults) and chromium (Cr) (TCR = 4.61 × 10⁻⁵ for children, 6.68 × 10⁻⁶ for adults) posed potential long-term cancer risks, exceeding the safe threshold (10⁻⁶) set by USEPA. Lead (Pb) and cadmium (Cd) had relatively lower carcinogenic risks, but their cumulative exposure remains a concern. The results reveal significant heavy metal contamination in quarrying communities, with potential long-term health consequences, particularly for children.