Accumulation and Risk Assessment of Heavy Metals in Vegetables in Wastewater Irrigation Areas

Concentrations of selected heavy metals (Cd, Cu, Pb, Cr and Zn) were determined in vegetables (radish, tomato, gourd, celery, lettuce, Chinese lettuce, Garland chrysanthemum, rape, Chinese cabbage, Sonchus) from the wastewater irrigation area in Tianjin, China. Cd contents in the edible parts were not significantly different among all vegetables. Zn concentration in the leafy vegetables was the highest of all the heavy metals. The metal contents in the vegetables were compared with the Chinese national standards for food quality. The contaminant index of Cr, Pb, Cd and Zn varied respectively between from11.96 to 22.26, from 5.36 to 14.43, from 0.95 to 15.4 and from 0 to 4.06. Although Cu content of the vegetables except lettuce was lower the permitted standard, the results indicated these vegetables could not be regarded as safety for human consumption.