Bioaccessibility and Health Risk Assessment of Heavy Metals in Agricultural Soil from Zhuzhou,China

Forty two agricultural soil samples were collected from Zhuzhou of Hunan province,China. The samples were analyzed to study the heavy metal bioaccessibility using SBET method,and to discuss their relationship with soil properties. In addition,the health risk assessment of the oral ingestion soil was carried out based on the common-used methods. The results showed that the concentrations of Cr,Cu,Zn,As,Cd and Pb in soils were 101-407,22. 9-139,64. 0-2286,5. 80-137,0. 310-26. 4 and 17. 9-691 mg/kg,respectively,while the bioaccessible concentrations of these metals were 3. 80-38. 1,1. 96-106,5. 06-1516,0. 160-53. 6,0. 140-21. 3 and 10. 8-570 mg/kg,respectively. The results showed a wide range of bioaccessibility of soil heavy metals. The rate of bioaccessibility of heavy metals were generally decreased as the order of Cd (66. 0%) Pb (59. 0%) Cu (44. 9%) Zn (35. 8%) As (16. 9%) Cr (5. 72%) .The bioaccessible heavy metals were well predicted by statistical models based on pseudototal contents,pH,organic matters and the total carbon. The health risk of soil heavy metals to children was obviously higher than that to adults. The average HI and TCR values of heavy metals to children were 8. 0 times and 1. 5 times higher than those to adults,respectively. Results based on the total metal contents might overestimate the actual human health risks in comparison with oral bioaccessibility assessment could reduce the risk significantly.After adjustment by bioaccessibility,the average HI and TCR values were reduced 71% and 74%,respectively. In contrast,the HI and TCR of some samples were still higher than the risk thresholds after adjustment by bioaccessibility and deserved our special attention.