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Human Health Risk Distribution and Safety Threshold of Cadmium in Soil of Coal Chemical Industry Area

Cadmium (Cd) is a highly carcinogenic metal that plays an important role in the risk management of soil pollution. In this study, 153 soil samples were collected from a coal chemical plant in northwest China, and the human health risks associated with Cd were assessed through multiple exposure pathways. Meanwhile, by the Kriging interpolation method, the spatial distribution and health risks of Cd were explored. The results showed that the average concentration of Cd in the soil was 0.540 mg/kg, which was 4.821 and 5.567 times that of the soil background value in Ningxia and China, respectively. In comparison, the concentration of Cd in the soil was below the national soil environmental quality three-level standard (1.0 mg/kg). In addition, health risk assessment results showed that the total carcinogenic risk of Cd was 1.269 × 10−6–2.189 × 10−6, both above the acceptable criteria (1 × 10−6), while the hazard quotient was within the acceptable level. Oral intake and ingestion of soil particles were the main routes of exposure, and the carcinogenic risk control value of oral intake was the lowest (0.392 mg/kg), which could be selected as the strict reference of the safety threshold for Cd in the coal chemical soil. From Kriging, a prediction map can be centrally predicted on heavy metal pollution in the area surrounding the coal entrance corridor and pedestrian entrance. This study can provide a theoretical basis for the determination of the heavy metal safety threshold of the coal chemical industry in China.