Toxic geogenic contaminants in wild foods and water along the great dyke and surrounding areas in Zimbabwe

• Wild foods contain TGCs in elevated concentrations relative to surrounding areas • E. natalensis and F. indica are safer for consumption relative to other wild foods • Geophagic material and termites consumption has high TGCs exposure risk • Wild fruits, herbs and water have a lower TGCs exposure risk compared to termites • Overall, TGCs in soils were significantly higher in SUG than GG environments Wild foods are essential to the diets of rural communities worldwide, particularly in developing countries. Wild foods and water found along Zimbabwe’s Great Dyke and in other serpentinic ultramafic geological (SUG) environments may contain toxic geogenic contaminants (TGCs). The objective of this study was to determine TGC concentrations in soils, water, wild foods and geophagic material consumed along the Great Dyke and surrounding granitic geological (GG) environment and evaluate their potential implications for human health exposure based on comparison with global guidelines. Wild fruits, medicinal plants, insects, rodents, geophagic material, water, and soils were collected from quadrats at eight sites within the SUG and the GG environments, and analysed for As, Cd, Co, Cu, Cr, Cr (VI), Fe, Mn, Ni, Pb, and Zn. Total concentrations of Cd, Co, Cr, Fe, Mn, Ni and Zn were significantly higher (p < 0.05) in soil from the SUG than soils from the GG environment. In borehole water, TGCs were below the detection limits (<0.01 mg/l), except for Cr and Mn, of which Cr concentrations from the SUG environment were significantly higher than those from GG environment, while Mn was significantly higher in the GG than in the SUG environment. Wild foods and geophagic material in this study contained all ten TGCs, with the SUG environment largely exhibiting higher concentrations. All fruits and medicinal plants exhibited moderate to high bioaccumulation factor (BAFs > 1) for at least one TGC in both environments. Euclea natalensis and Flacourtia indica showed lower TGC concentrations relative to other wild foods assessed. Consumption of wild foods and geophagic material from the SUG and similar environments may increase TGC health concerns as their levels exceeded permissible limits, except for Zn in fruits, medicinal plants, and water. Future studies to conclusively separate the contributions of geogenic and anthropogenic sources of TGCs and assessing potential human health risks are recommended.