Human Health Risk of Some Heavy Metals in the Surface Soil of Arak Plain

Soil contamination with heavy metals is becoming a major environmental concern today. Therefore, the present study was conducted to evaluate the health risks of heavy metals in the surface soil of Arak plain.

Soil samples were collected by random sampling from 30 stations with three replications from a depth of 0-20 cm. After acidic digestion of the samples (HNO3: HclO4: HF = 3: 2: 1), the concentrations of lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), and cadmium (Cd) were determined by atomic absorption spectrometry. Finally, the carcinogenic and non-carcinogenic hazards of heavy metals in surface soils for human health were assessed through ingestion, inhalation, and dermal absorption using the method recommended by the EPA for children and adults.

The results indicated that the average total concentrations of heavy metals of Pb, Zn, Cu, Ni, and Cd in the study area are 10.01, 13.83, 39.82, 43.41, and 11.9 mg/kg, respectively. The highest and lowest average daily dose (ADD) of elements in both age groups were related to Ni metal from the ingestion route and Cd metal from the inhalation tract, respectively. Further, the non-carcinogenic risk hazard quotient (HQ) of heavy metals in all three paths was less than 1. The results of the non-carcinogenic hazard index (HI) risk assessment of all three pathways separately for each metal and for both groups of children and adults showed metal values as Cu > Cd > Zn > Pb > Ni, respectively. In addition, the results of the carcinogenic risk index (RI) in the surface soil of Arak plain revealed that Ni and Pb have the highest and the lowest carcinogenic risk, respectively.

Finally, considering the size of the study area and proving the carcinogenic hazards and risks in the area, it is necessary and important to pay attention to health and environmental principles.