Evaluating the contamination of soil, water and vegetables with heavy metals along with the estimation of transfer factor and human health risk in Gondar city, Ethiopia
Molla Tefera, Berhan Solomon, Atnafu Guadie, Worku Lakew, Banchamlak Sewachen, Desta Shumye
Abstract
Vegetables are consumed in greater quantities in Ethiopia and are necessary for human life. However, growing vegetables using wastewater could be harmful to the health. Thus, in this study, the levels of metals were determined in the leaves of lettuce, Swiss chard, and Ethiopian kale and the tubers of potato samples, water and soil around Gondar city, and their health risks were also evaluated. The levels of Fe, Zn, Cd, Cr, Mn, Pb and Cu in vegetables ranged from 301.9 to 1017.9, 19.2 to 41.6, 11.6 to 13.7, 3.9 to 5.0, 7.4 to 206.4, 10.4 to 21.2 and 18.7 to 60.8 mg/kg, respectively. The lowest and highest values in vegetables, soil, and water were Cr and Fe, respectively. The levels (mg/kg) of Cd and Pb in vegetables, Fe and in lettuce and Swiss chard, and Cu in all vegetables except potato were above the values set by FAO/WHO. The Cu and Fe levels in soil, Cd, Pb, Fe, and Mn, in water were also higher than FAO/WHO recommended levels. Higher values of these metals above the recommended level are attributed to high agricultural runoff containing fertilizers and pesticides, industrial pollution, improper household waste disposal, and leaching of old plumbing systems. The values of hazard index (HI) for every vegetable studied were below unity, and the incremental lifetime cancer risk (ILCR) values were also below the tolerable range (10− 4), showing that consuming such vegetables has no non-carcinogenic or carcinogenic health risks. The findings underscore the importance of recognizing possible hotspots of water, soil, and vegetable pollution to ensure monitoring the metals.