LAUSR

Abstract Assessment of heavy metals accumulation in vegetables and their levels in human is vital in countries where wastewater is used for irrigation. In this study, I determined the concentrations of highly toxic metals such as Nickel (Ni), chrome (Cr), lead (Pb), zinc (Zn), cadmium (Cd), and copper (Cu) in wastewater, farmlands soils and vegetables (chard, celery, cress and leek), and also their possible human health risk in the area of Erbil city. The heavy metals concentration in the vegetable, soil and water samples were analyzed by using an atomic absorption spectrophotometer. Bio-concentration factor (BCF), daily intake (DI) and health risk index (HRI) were calculated in order to estimate the human health risk. Overall, results indicated that the water, soil and vegetable samples were contaminated with Ni, Cd, Cr, Cu, Pb, and Zn. The trends of these metals concentrations were as follows: 0.613 > 0.316 > 0.162 > 0.065 > 0.041 > 0.028 mL/L for Ni, Cd, Pb, Cr, Cu, and Zn, respectively in the wastewater and 189.09 > 125 > 104.92 > 41.85 > 28.58 > 21.72 for Zn, Cr, Ni, Pb, Cu and Cd mgkg-1 in the soil. The mean concentrations (mg kg-1) in the vegetable samples ranged from 22.74 to 30.30, 5.18 to 9.19, 29.50 to 33.87, 39.42 to 64.78, 7.87 to 11.83 and 77.68 to 117.98 for Ni, Cd, Pb, Cr, Cu and Zn, respectively. In addition, the BCF values ranged from 0.21 to 71.295, with Pb having the highest BCF. The DI for Ni, Cd and Pb exceeded the WHO/FAW safe limits for both children and adult while the HRI values of Cd and Pb exceeded the safe limit for both adults and children, but the HRI for Ni only exceeded the value for children. These findings clearly indicate that the practice of irrigating the vegetables with untreated wastewater by local farmers have caused high accumulation of heavy metals in the soils and vegetables which are posing health risk to the population in the vicinity. Therefore, regular monitoring of these metals in the wastewater-irrigated vegetables is necessary.