Sources, pathways, and health risk assessment of harmful elements in soil and crops: a case study from East Cameroon

This study aimed to assess the contamination of soils by potentially harmful elements (PHEs), their transfer to food crops, and the potential health risks to humans. Samples of four rock types, ten soil samples, and six staple food crop samples were collected from representative sites and analyzed for cations using inductively coupled plasma mass spectrometry and for anions using ion chromatography. The mean concentrations (mg/kg) of Fe, Al, Cr, Mn, Ba, Zn, Pb, NO₃⁻, Ni, Cu, Co, As, Se, and F⁻ exceeded the safe limits set by the Food and Agriculture Organization. The pollution load index was > 3 for Mn, Cr, Pb, Se, and NO₃⁻. The geoaccumulation index was > 1 for all elements except Se. The ecological risk index was > 300 solely for Mn. Statistical analysis and GIS-based geospatial plots indicated pollution from both geogenic and anthropogenic sources. Non-carcinogenic risk (HQ) was > 1 for NO₃⁻ and Fe in adults and > 1 for Mn, Fe, Al and Cr in children. The bioaccumulation factors were higher in vegetables than in grains. The cumulative hazard index (HI) was low for Cr, Co, and Se in adults, while in children, it was low for Ni, Se, and Ba. Carcinogenic risk indices indicated that Cr posed the highest risk among all PHEs, with children being more vulnerable than adults. Overall, children had a higher exposure to PHEs compared to adults. The findings highlight the human health risks associated with PHE exposure from contaminated agricultural systems, particularly in semi-arid regions.