Health Risk Assessment of Heavy Metals in Soil from the Iron Mines of Itakpe and Agbaja, Kogi State, Nigeria

Abstract

The study evaluates associated health risks of heavy metals in the soil to inhabitants of two mining areas of Nigeria. For so doing, it collects and analyses nine homogenous soil samples for their lead, copper, cadmium, zinc, and chromium levels, using AAS. The samples are then used to calculate health risks to adults and children. For adult population in Agbaja community, the calculated hazard quotients fall below one in all considered pathways. Hazard index values for all the pathways are also less than one, taking the following order: Cu>Cr>Pb>Cd>Zn. It is shown that for all considered heavy metals, the adult population in Agbaja mining community was not at any risk of non-carcinogenic effects from these metals. As for the children in Agbaja, the calculated HQ values for Cd and Zn have been less than one in all the pathways, while the HQ values for Pb, Cr, and Cu have significantly surpassed 1, with the ingestion route being the main pathway. The HI values have been in the following order: Cu>Cr>Pb>Cd>Zn, which poses serious non-carcinogenic health risks to the children, living around this community. The carcinogenic risk has been calculated based on Pb, Cd, and Cr, with the former (Pb) proven to be the highest contributor to cancer risk. USEPA considers acceptable cancer risk within the range of 1×10⁻⁶ to 1×10⁻⁴. Though insignificant in its values, carcinogenic risk for adults in Agbaja (2.95×10^-4) and Itakpe (4.71×10^-4) and for children in Itakpe (4.47×10^-4) have been higher than the acceptable values. Hence, the adults are more at risk, for whom ingestion is the main contributor to excess lifetime cancer risk, followed by dermal pathways. Considering the health hazards, entailed by the accumulation of these heavy metals, on human health, mining sites and areas require to get monitored properly.