Health risk assessment of heavy metals via dietary intake of vegetables irrigated with treated wastewater around Gaborone, Botswana

Abstract

Heavy metal concentrations of Cd, Cr, Cu, Ni, Pb and Zn in green peppers (Capsicum annuum) and tomatoes (Solanum lycopersicum) irrigated with treated wastewater from the Glen Valley farms were determined. Concentrations of Cr, Pb and Zn were significantly high when compared with their respective recommended safe limits prescribed by the Joint WHO/FAO Food Standards Program Code Alimentarius Commission. The daily intake of metals, DIM values for Cr and Pb were also found to be higher than their recommended safe limit values, whereas those for Cd, Cu and Ni were within the safe limit values while that for Zn was far below the recommended safe limit value. In this study, we expect that consumption of Cr and Pb through vegetables poses substantial health risk to consumers and for this reason, these products are probably not recommended consumption. Therefore, this emphasizes the need for proper method to manage using wastewater to reduce the health risk and the extent of heavy metals contamination.