Contamination Levels and Human Health Risk Assessment of Heavy Metals in Soil from the Royal Salt Mining Site, Ikwo, Ebonyi State, Southeastern Nigeria

Background and Objective: Heavy metal contamination in residential soils near mining sites poses significant health risks. The Royal Salt mining site in Ikwo, Ebonyi State, may contribute to elevated levels of Pb, Cr, and Cd in surrounding soils. This study aims to evaluate the chronic daily intake of Lead (Pb) and Chromium (Cr) for both adults and children through ingestion and dermal exposure. Additionally, it seeks to assess the potential non-carcinogenic and carcinogenic health risks associated with heavy metal exposure in residential soils. Materials and Methods: A total of 100 soil samples were collected from the study area at a depth of 0-10 cm using a soil auger and core sampler at a horizontal spacing of 100 m between each location (A, B, C, D, and E) points in 2024. The soils were analyzed for Pb, Cr, and Cd using an atomic absorption spectrophotometer. Results: The mean concentrations of Pb and Cr in soil samples were 70.6 and 83.6 mg/kg, respectively, while Cd was not detected. The hazard quotient (HQ) for Pb via ingestion was above one for both adults (22.8) and children (11.43), indicating potential health risks, whereas the HQ for Cr and all dermal exposures were below one. Cancer risk values for Pb and Cr via ingestion and dermal exposure ranged between 10^–6 and 10^–4, indicating an acceptable cancer risk level. Conclusion: The findings indicate that residents near the Royal Salt mining site are at risk of non-carcinogenic health effects due to Pb exposure via ingestion. However, the carcinogenic risk for both Pb and Cr remains within acceptable limits, suggesting no significant cancer risk for residents.