Ecological and Human Health Risks of Potentially Toxic Elements and Naturally Occurring Radioactive Elements in Food Crops from Soils in Mampong, Ghana.

Abstract

This study examines the levels, spatial distribution, and health risks of naturally occurring radioactive materials (NORMs) and potentially toxic elements in agricultural soils and food crops (cassava, yam, and cocoyam) in Mampong Municipality. The research focuses on uranium-238, thorium-232, potassium-40, and heavy metals such as cadmium, chromium, lead, and arsenic, which pose environmental and health risks. The study’s findings reveal that the soils are mildly acidic (average pH ~ 6.25), a condition conducive to increased metal solubility and bioavailability, which enhances the transfer of metals to plants. Key physicochemical parameters, such as electrical conductivity and organic carbon content, indicate that soils have low ionic contamination but varying capacities for metal retention and mobility. Potentially toxic elements concentrations in soils exhibited a consistent trend (Mn > Zn > Cr > Ni > Cu > Pb > Cd > As), with manganese and zinc as the most abundant, though potentially harmful elements like cadmium, chromium, and lead exceeded permissible limits in several locations. Mn concentrations, although the highest among metals tested, generally remained within safe levels and posed lower risks to human health and the environment. Zn concentrations were notable but also largely within acceptable limits, indicating moderate environmental concerns. However, the comparison highlights the variability of these metals’ risks depending on location and other soil factors such as pH and organic content. Radionuclide measurements identified moderate activity concentrations of uranium-238, thorium-232, and potassium-40, with calculated hazard indices generally within acceptable limits but with specific areas showing elevated risks. The study found high metal transfer rates from soil to crops, particularly for manganese, chromium, zinc, and cadmium. Cocoyam showed the highest bioaccumulation, with cadmium and chromium posing non-carcinogenic risks to children. Lifetime cancer risk assessments suggest long-term exposure concerns. The research highlights the need for continuous environmental monitoring and regulatory interventions to mitigate contamination risks. Public awareness initiatives and stricter policies are recommended to protect food safety, human health, and the ecosystem.