Regional assessment of cadmium pollution in agricultural lands and the potential health risk related to intensive mining activities: a case study in Chenzhou City, China.

The purpose of this study was to assess the extent of cadmium (Cd) contamination in agricultural soil and its potential risk for people. Soils, rice, and vegetables from Chenzhou City, Southern China were sampled and analyzed. In the surface soils, the 95% confidence interval for the mean concentration of Cd varied between 2.72 and 4.83 mg/kg (P < 0.05) in the survey, with a geometric mean concentration of 1.45 mg/kg. Based on the GIS map, two hot spot areas of Cd in agricultural soils with high Cd concentrations were identified to be located around the Shizhuyuan, Jinshiling, and Yaogangxian mines, and the Baoshan and Huangshaping mines, in the center of the city. About 60% of the total investigated area, where the agricultural soil Cd concentration is above 1 mg/kg, is distributed in a central belt across the region. The critical distances, at which the soil Cd concentration were increased by the mining activities, from the mines of the soils were 23 km for the Baoshan mine, 46 km for the Huangshaping mine, and 63 km for the Shizhuyuan mine, respectively. These are distances calculated from models. The Cd concentrations in rice samples ranged from 0.01 to 4.43 mg/kg and the mean dietary Cd intake from rice for an adult was 191 microg/d. Results of risk indexes showed that soil Cd concentrations possessed risks to local residents whose intake of Cd from rice and vegetables grown in soils in the vicinity of the mine was 596 microg/d.