Migration of Selenium in Soil-rice-human System and Its Health Risk Assessment in Enshi

In order to to provide scientific reference for the management and development of selenium resources in Enshi, four soil samples and four relevant rice samples were collected from four regions of Enshi, and then selenium content in the soil and rice samples were measured by ICP-MS. Afterwards, the occurrence forms of selenium in the soil samples were detected by continuous extraction. At last, the bioavailability of selenium in rice was studied by the in vitro gastrointestinal model. The results showed that selenium content in soil was 0.15-5.42 mg/kg in Enshi. The proportion of water-soluble selenium in soil was the lowest, ranging from 1.41% to 3.80%; the proportion of residual selenium was the highest, reaching 36.1%-41.7%. Besides, selenium content in rice was 0.07-1.61 mg/kg, and the bioconcentration factor of selenium in rice was 0.22-0.48. The bioaccessibility of selenium in rice ranged from 45.7% to 56.4% in the stomach and from 58.4% to 68.5% in the small intestine. In addition, the daily intake of selenium per capita (PDI) in Yutangba, Changping, Shadi, and Taiyanghe was 490, 26, 132 and 57 μg/d, indicating that people in Yutangba had the risk of chronic selenium poisoning, and people’s diet was rich in selenium in Shadi and Taiyanghe, while people’s diet was deficient in selenium in Changping.