Comparative evaluation of groundwater, wastewater and canal water for irrigation on toxic metal accumulation in soil and vegetable: Pollution load and health risk assessment

Accumulation of toxic heavy metals (THMs) in the soil-water-plant can negatively affects regional eco-safety and poses a threat to agricultural productivity, ecosystem, animals, humans and plants. Additionally, THMs can enter human bodies through the food chain, leading to an increased incidence of chronic diseases such as deformity and cancer. Leafy vegetables irrigated with untreated as well as contaminated waters were usually abounded with heavy metals in high concentrations. These contaminated leafy green vegetables although very popular here, may cause threats to human health, since these are usually grown in sub-urban areas, by irrigations of the untreated contaminated waters (canal water, groundwater and waste water carrying many city effluents). In this study, we analysed and measured the levels of hazardous metals (Zn, Cr, Ni, Cd, Cu, Fe and Pb) found in spinach (Spinacia oleracea L.) at 3 different places of district Sargodha. Results revealed that the measured concentrations of Cd in water and spinach, and that of Pb in spinach were exceeding the standard permissible limits. High values of health quotient were found for Cr, Cd and Pb. The sequence of EC was recorded in ascending order as Pb > Cr > Cd > Ni > Zn > Cu >Fe in all the samples which were examined. The results of the study conclude, as the heavy metals are carcinogenic for human health, not only proper monitoring of soil and irrigation water should be made as well as such contaminated vegetables may be avoided.