[Bioaccessibility of soil cadmium and its health risk assessment]

Sixteen soil samples were collected from different sites of China to study the bioaccessibility of soil cadmium. The relationship between the soil properties and the bioaccessibility as well as the health risk assessment of the oral ingestion soil was also studied. The results showed that comparing with Chinese environmental quality standard for soils, the concentrations of cadmium in 11 soil samples were higher than the standard. The high variability of dissolved and bioaccessible cadmium of soils were observed. Concentrations of bioaccessible Cd ranged from 0.05-20.71 mg x kg(-1) and 0.03-11.99 mg x kg(-1) with a mean of 1.81 mg x kg(-1) and 1.06 mg x kg(-1) in gastric and small intestinal phase respectively. Bioaccessible Cd ranged from 6.37%-69.43% and 3.19%-36.91% with a mean of 25.34% and 14.84% in gastric and small intestinal phase respectively. A significant correlation between dissolved cadmium in gastric stage with the soil pH was also observed. In gastric stage, for children, the highest contribution of the oral ingestion soil cadmium to the provisional tolerable weekly intake (PTWI) that recommended by WHO was 26.90% in the soil sample that was collected from Nanning Guangxi and the contribution rate in 11 soil samples is lower than 1.00%. In small intestinal stage, for children, the contribution of the oral ingestion soil cadmium to PTWI was also variable. The highest contribution rate was 15.57%, the four samples were higher than 1.00% and others were below 1.00%. Health risk from the oral ingestion of soil cadmium was low in most of soils and the high health risk only occurred in the soil sample with high total cadmium concentration and high bioaccessibility.