Introduction: Globally, pollutants, such as heavy metals and nitrates, from both natural and anthropogenic sources threaten groundwater, posing significant risks to human health and the environment.
Methods: This study assessed the health risks to adults and children resulting from oral and dermal exposure to heavy metals (Pb, As, Cd, Cr, Fe, Ni, and Mn) and nitrates in the groundwater of Mariri, Nigeria, in 2024. Non-carcinogenic and carcinogenic risks were assessed using methods from the US Environmental Protection Agency.
Results: Cd is the only pollutant that poses a significant non-carcinogenic risk (HQ > 1) and is the major contributor to the total risk to adults (73.06%) and children (74.69%). The hazard index through the oral exposure route is greater than one (HI > 1), whereas that through the dermal route is less than one (HI < 1) for adults and children. The multi-route hazard index (MHI) is greater than one for adults (2.49) and children (2.73), suggesting a significant non-cancer risk. The oral route contributed a higher risk than the dermal route for both receptors; children are more at risk (53%) of non-cancer health effects than adults (48%). There was also a significant cancer risk (CR > 10−4) for adults through oral exposure to Cd and Ni, and children through dermal exposure to Cr, leading to significant cumulative cancer risk (RI) for adults through the oral route and for children through the dermal route.
Conclusion: This study indicates a significant non-cancer risk, particularly due to Cd, and cancer risk due to Cd, Ni, and Cr, thus necessitating corrective measures.