Human health risk hazards by heavy metals through consumption of vegetables cultivated by wastewater

Abstract

Need for irrigated agriculture is rising daily, but quality water for irrigation is on the decline, necessitating the use of urban wastewater as alternative source, particularly in low or middle income countries. This study assessed the effect of urban wastewater irrigation on the quality of groundwater, soil and vegetables in farms around Faisalabad, Pakistan. Human health risks of heavy metals were investigated through consumption of wastewater irrigated vegetables. Samples of soil, vegetables and water were obtained and analyzed for heavy metal concentrations (cadmium, Cd; lead, Pb; manganese, Mn; nickel, Ni; cobalt, Co; and zinc, Zn). The groundwater could be declared safe for consumption in the present state, as concentration of heavy metals standards. But wastewater-irrigated vegetables had higher Pb, Cd and Mn than the permissible limits. In wastewater-irrigated vegetables, highest HRI-Pb was recorded in mustard leaf and cabbage and was >1. EF for Zn and Mn in all vegetable plants, Ni in potato and cauliflower, Pb in mustard leaf and cabbage were >1.5, suggesting that the metals were generated by anthropogenic processes (such as wastewater irrigation). Long-term irrigation of farmlands with the wastewater will result to heavy metal contamination of groundwater, soil and vegetables in the study area. Therefore, strategies to save the groundwater from future contamination are necessary.