Bioaccessibility and Human Health Risk Assessment of Heavy Metals in Soils of Antimony Mine Area

The total contents and pollution status of heavy metals (Fe, Mn, Cu, Zn, Pb, Cd, As and Sb) were investigated in 29 soil samples collected from antimony mine area in Xikuangshan, Lengshuijiang City, Hunan Province. The simple bioaccessibility extraction test (SBET) was used to evaluate the bioaccessibility of heavy metals in soils. In addition, the human health risk assessment of the oral ingestion soil for adults was carried out based on the human health risk model. The results showed that As and Sb are the main pollution elements in the soils, and they have high homology and are easily affected by human activities. Bioaccessibility of soil heavy metals covered a wide range, the rate of bioaccessibility of heavy metals decreased in the order of Mn(36.7%) > Cd(30.7%) > Pb(24.4%)>Zn(23.1%) > Cu(12.0%) > As(5.89%) > Fe(3.88%) > Sb(2.13%), indicating that most of the heavy metals through oral ingestion could not be adsorbed by human body. The results based on total metal contents might overestimate the actual human health risks. After adjustment by bioaccessibility, the health risk values were greatly reduced, the average hazard index (HI) and total carcinogenic risk (TCR) values were reduced by 97% and 92%, respectively. Sb and As are two predominant contributors to human health risks. In addition, the hazard index values of some samples in tailing dam area were still higher than the risk threshold value after adjustment by bioaccessibility and deserved special attention.