Evaluating heavy metal accumulation and potential health risks in vegetables irrigated with treated wastewater

Effect of irrigation with treated municipal wastewater on the accumulation of heavy metals in soils and food crops and potential health risks to human via consumption of these food crops are evaluated. The higher concentrations of iron (Fe), copper (Cu), chromium (Cr) and zinc (Zn) were found in lettuce, radish and carrots, respectively. However, trace metal levels in all vegetables were far lower than the food safety criteria of World Health Organization and European Union. Bioaccumulation factors (BAF) for heavy metals in different vegetables showed a trend in the order: Fe > Zn > Cu > Cr. The trends of estimated dietary intake (EDIs) for adults were in the order of Fe > Zn > Cr > Cu. The highest level of total coliform was recorded in spinach, followed by radish, egg plant, tomatoes and lettuce. The low uptake of heavy metals by vegetables shows that the health risks for human are insignificant. As the variations in transfer factor of metals is related to absorption capability of vegetables, soil properties and nutrient management, the risk of human exposure to metal contamination can be significantly reduced by selecting appropriate crops.