Ecological and health risk assessment of cadmium in soil of ten provinces and cities, China

Objective To investigate the status of heavy metal cadmium (Cd) pollution in soil of ten provinces and cities and its ecological and health risks in China, so as to provide a scientific basis for related departments to formulate measures for the prevention and control of pollution and health risks.

Methods The surveillance data of soil heavy metal Cd content were obtained from 1 730 samples at 1 200 sites in the ten provinces and cities across China from 2013 to 2020, and ecological and health risks were assessed based on single-factor pollution index and the health risk assessment model of the United States Environmental Protection Agency (US EPA) respectively.

Results The mean concentration of Cd was 0.29 mg/kg in all 1730 soil samples, and the rate of sites with Cd content unqualified was 29.6%(355/1 200); the highest concentration of Cd was observed in 2016 (0.42 mg/kg) and the lowest concentration was observed in 2018 (0.21 mg/kg). The single-factor pollution index analyse showed slight Cd contamination in 269 soil samples, moderate Cd contamination in 72 samples, and heavy Cd contamination in 37 samples. Health risk assessment result showed that the carcinogenic risk of Cd ranged from 1.63×10^-9 to 2.09×10^-5 for children and ranged from 8.58×10^-10 to 1.10×10^-5 for adults, both of which were lower than the maximum acceptable value of 10^-6 proposed by US EPA. However, Cd in 500 soil samples showed a carcinogenic risk ranged from 10^-6 to 10^-4 for children, and Cd in 148 soil samples showed a carcinogenic risk ranged from 10^-6 to 10^-4 for adults. As for spatial distribution, Cd concentration, ecological risk, and health risk in southern China were higher than those in northern China, and the carcinogenic risk of soil Cd was more than 10^-6 for children in some western, central, and western provinces. The hazard quotient (HQ) values were all below the threshold of 1.

Conclusion There is a relatively low non-carcinogenic risk of heavy metal Cd in soil samples of the ten provinces and cities in China, which is not expected to cause obvious non-carcinogenic risk, but heavy Cd pollution is observed in some areas, which may have caused carcinogenic health risk to the local population. Therefore, Cd pollution should be taken seriously and prevention and control measures should be adopted.