Health Risk Assesment of Heavy Metals in Vegetables from Wastewater Irrigated Area in Addis Ababa, Ethiopia

This study assessed the concentrations of toxic and potentially toxic elements (Cd, Pb, As, Cu, Zn, Cr, Co, Ni, Ba, B, Sr, V, Fe and Mn) in agricultural soils and vegetables irrigated with wastewater and their possible human... [ view full abstract ]

This study assessed the concentrations of toxic and potentially toxic elements (Cd, Pb, As, Cu, Zn, Cr, Co, Ni, Ba, B, Sr, V, Fe and Mn) in agricultural soils and vegetables irrigated with wastewater and their possible human health risk in Addis Ababa. The result revealed that concentrations of Cr, Cd, Pb and Fe in most vegetables surpassed the maximum recommended levels. Pollution levels were varied with metals and vegetable types. The average concentrations (mg/kg) of all elements in the vegetables were found in order of Pb > Fe > Mn > Sr > Zn > Ba > B > Cu > Cr > Ni > V > Co > As > Cd. Many of the concentrations were higher than previously reported. Moreover, the concentrations of Cu, Mn, Sr, Ba, B, Sr, Co, Pb and Zn in the soils were shown significant correlations with those in the vegetables. The metal transfer factor was found highest for B followed by Pb > Sr > Zn > Cd > Cu > Ba > Cr > Mn > As > Ni > V > Co > Fe. Metal pollution index showed that Swiss chard was maximally contaminated with metals followed by carrot, lettuce, cabbage, kale and potato that had a significant threat of negative impact on human health. The health risk assessment data also revealed that a high level of hazard quotient (˃1) for Pb in all vegetables except cabbage, Sr in Ethiopian Kale, Mn in Ethiopian kale, lettuce, cabbage and Swiss chard, Cu in lettuce, Swiss chard and carrot, As and Fe in all the vegetables except potato, Zn in lettuce and Swiss chard, Ba in Ethiopian kale and Swiss chard and B in Swiss chard were recorded that would pose a potential health risk to the consumers. This study highlights the need for proper treatment and disposal of wide range of effluents and waste materials and regular monitoring of potential contaminants in water, soil and vegetables and enforcement of standards.