Health risk assessment of heavy metals/metalloid caused by using sewage sludge in agriculture

The use of sewage sludge in agriculture is considered as an available option, especially in developing countries. However, due to sludge pollutants, including heavy metals/metalloid as potentially toxic elements (PTE), there are serious health and environmental concerns. In this study, the health risk caused by heavy metals/metalloid in the using of sewage sludge in the agricultural lands of Khoy, Iran was investigated. The results showed that the concentration of heavy metals/metalloids in studied sewage sludge ranged from 0.38 to 11,228.22 mg/kg. The pH of the studied sludge was in the range of 6–7, which was not recognized as a synergistic factor for penetration or precipitation of metals in the soil. The calculated Hazard Index (HI) for adults and children was 0.264 and 0.530, respectively. The highest Hazard Quotient (HQ) was related to As, Zn, Hg, and Cr. The total carcinogenic risk of using studied sewage sludge in agriculture was calculated to be 2.12E-03, which indicated the occurrence of carcinogenic risk. The advantages of using sewage sludge in agriculture, including increasing soil fertility, have increased the desire to use this option in sludge management, but the results of this study showed that the development of sludge treatment processes led to a reduction in the concentration of heavy metals/metalloid, a necessity before its use in agricultural land.