Selenium Content in Staple Crops and Drinking Water and Associated Health Risk Assessment: A Case Study of a Selenium-Rich Region in Southern Shaanxi, China

To study the selenium (Se) content and dietary risk in typical Se-rich regions (the soil Se thresholds were as follows: high Se at 0.4-3.0 mg/kg and excessive Se at >3.0 mg/kg), the northern of Langao County, Ankang City, Shaanxi Province was studied. Contents of Se in crops and drinking water were analyzed. The average Se contents in drinking water was 12.32 μg/L in the excessive-Se and 13.50 μg/L in the high-Se areas. Corn, rice, sweet potato, and eggplant exhibited the highest average Se contents in the excessive-Se area, while potato and radish showed the highest levels in the high-Se area. Adults (and children) living in excessive-Se areas had a mean daily Se intake of 598 (305) μg/day, and those in high-Se areas had an intake of 536 (275) μg/day. Although crops were the main dietary source of Se, the contribution of drinking water, particularly for children, should not be overlooked as an additional source of Se intake. The average hazard quotients of adults (children) from excessive-Se and high-Se areas were 1.77 (1.95) and 1.58 (1.76), respectively. Therefore, there are non-carcinogenic health risks for humans in the two regions.