Accumulation of heavy Metals in Soil and Green Leafy Vegetables, Irrigated with Wastewater

The present study was carried out to assess the level of Cd, Pb, Zn, Cu, Cr, and Ni in soil and edible portion of green leafy vegetables, grown in soil irrigated with wastewater near to katihar town and impact on health of residents of the study area. Results revealed that concentration of Pb, Zn, Cu, and Ni in some agricultural fields and Cd in all fields exceeded the normal soil value but lower than critical soil value. The accumulation of Cd, Pb, Zn, Cu, Cr, and Ni varied from 0.48-1.51, 2.5-25.5, 60.3-134.5, 5.15-18.7, 1.45-6.22 and 3.5-9.2 mg kg1 respectively, in leafy shoot of the vegetable plants, which were higher than root of corresponding test vegetable plant. The soil–plant transfer factor (TF) decreased in the following orderTFZn > TFCd > TFCu > TFN i > TFPb > TFCr. Transfer factor more than 0.50 was obtained for Zn, Cd and Pb. The daily intake of heavy metals was found to be lower than the provisional tolerable daily intake (PTDIs) set by the Joint FAO/WHO Expert Committee on food additives and minimal risk levels (MIR) value suggested by AQTSDR. The average value of human health risk index (HRI) for different metals was found in following order Pb (0.726) > Cd (0.327) > Ni (0.1083) > Cu (0.094504) > Zn (0.0652) > Cr (0.00798).The data revealed that HRI value of all individual vegetables were below than 1.0 except Pb (1.689) for mustard. Therefore, it is suggested that regular monitoring of heavy metals in vegetables is essential to prevent excessive build –up of heavy metals in the food chain and further use of wastewater for irrigation should be avoided.