Heavy metals in vegetables grown in the vicinity of Hawassa industrial zone, Ethiopia: Estimation of possible human health risks

Concentration of heavy metals (Cr, Ni, Cu, Zn, As, Cd, Pb and Hg) in cabbages and potatoes were determined and the potential human health risks due to the consumption of the vegetables have been estimated. Mean concentrations of Zn (134.0 + 5.62 mg/kg), As (0.12 + 0.01 mg/kg) and Cd (0.32 + 0.01 mg/kg) in cabbages from Biological Lagoon area as well as Zn (103.0 + 8.34 mg/kg), As (0.14 + 0.01 mg/kg) and Cd (0.31 + 0.01 mg/kg) in cabbages from Boicha stream area were above the safety limits of FAO/WHO. Likewise, mean concentrations of As (0.24 + 0.03 mg/kg) in potatoes from Biological Lagoon area as well as As (0.35 + 0.07 mg/kg) and Pb (0.50 + 0.04 mg/kg) from Boicha stream area were also above safety limits. Assessment of Target Hazard Quotients (THQ) indicated no human health concern from consumption of both cabbages and potatoes grown in the areas except as through consumption of potatoes from Biological Lagoon and Boicha stream areas. However, effects of all the metals put together may affect human health as revealed by the high Hazard Index (HI > 1). Assessment of Target Cancer Risk (TCR) revealed human health concern from consumption of these vegetables for As and Cd. Overall, vegetables consumption from industrial zone is more risky than consuming vegetables from the Reference site indicating effluents from industries to be a potential sources of the heavy metals.