Concentrations and Health Risk Assessments of Heavy Metal Contents in Soil and Rice of Mine Contaminated Areas

Abstract

Nandan County is famous for its mining of nonferrous metals. In order to investigate the effects of mining activities on the soil and rice and to evaluate the health risk of the exposure of typical local inhabitants to heavy metals via consumption of rice, a consecutive 3-day household diet survey in four villages in Nandan was conducted. Liuzhai is an uncontaminated contrast area, and Chehe, Dachang, and Zhanglao are contaminated areas. The data for rice consumption rates were obtained. At the same time, 56 soil samples from rice fields and 90 rice samples were collected for the analysis of As, Sb, Cd, Pb, Cu, and Zn. In addition, the potential health risk of the exposure of local people to heavy metals via consumption of the rice was assessed using the pollution index method and the data from the intake of heavy metals. Results showed that the mean contents of As, Sb, Cd, Pb, Cu, and Zn were 58.1, 16.4, 1.22, 49.1, 52.1, and 271 mg·kg-1 in the soil samples from contaminated areas, with higher pollution risks than from the control area for soil heavy metal contents. The Nemero comprehensive contamination index (PN) was 3.14, a heavy pollution grade. Cd contents in rice in Liuzhai, Chehe, Dachang, and Zhanglao were 2.23 times, 4.40 times, 3.81 times, and 3.52 times higher than those of GB 2762-2017.The content in rice exceeds the standard in all four areas. The daily intake (DI) of Cd in the four areas was higher than the provisional tolerable daily intake (PTDI) established by FAO/WHO. This indicates that Cd and As are the major heavy metal elements posing health risks to the health of the inhabitants in the mining areas and that the inhabitants in the mining areas are facing severe risks of exposure to heavy metals.