Soil selenium concentration and residents daily dietary intake in a selenosis area: A preliminary study in Yutangba Village, Enshi City, China

Authors: LONG, ZEDONG - Hefei University Of Technology; XIANG, JIQIAN - Hubei Academy Of Agricultural Sciences; SONG, JIAPING - University Of Science And Technology Of China; LU, YAPU - University Of Science And Technology Of China; YIN, HONGQING - Academy Of Agricultural Science; ZHU, YUNFEN - Academy Of Agricultural Science; LIU, XIAODONG - University Of Science And Technology Of China; QIN, LIQIANG - Medical College Of Soochow University; Banuelos, Gary; WANG, ZHANGMIN - Suzhou Institute For Advanced Study, Ustc; KANG, YU - Academy Of Agricultural Science; YUAN, LINXI - Liverpool University; YIN, XUEBIN - Hefei University Of Technology

Submitted to: Bulletin of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2020
Publication Date: 9/9/2020
Citation: Long, Z., Xiang, J., Song, J., Lu, Y., Yin, H., Zhu, Y., Liu, X., Qin, L., Banuelos, G.S., Wang, Z., Kang, Y., Yuan, L., Yin, X. 2020. Soil selenium concentration and residents daily dietary intake in a selenosis area: A preliminary study in Yutangba Village, Enshi City, China. Bulletin of Environmental Contamination and Toxicology. 105:798-805. https://doi.org/10.1007/s00128-020-02983-x.
DOI: https://doi.org/10.1007/s00128-020-02983-x

Interpretive Summary: Selenium (Se) is an essential trace element required on a daily basis for humans. However, a high Se intake can lead to a range of health disorders, such as hair loss, weak nails, garlic breath odor, tooth decay and discoloration. Because the range for safe Se intake is rather narrow, humans living in Se-rich areas need to pay attention to the amount of Se they consume via agricultural food products. In northwestern Enshi China, the village of Old Yutangba is well-known as the only Se-mine in the world. In 1963, villagers in Old Yutangba experienced hair and nail losses, which are characteristic symptoms of natural selenosis. For this reason, a series of preliminary studies were performed to investigate the sources, distribution, and factors associated with Se concentrations at this village site. These studies evaluated Se content in soils, vegetables, meat products, as well as Se content in hair and blood from the local residents. Total intake of Se was calculated based upon their daily consumption of food and animal products. Results showed that that the high Se content found in hair and blood originated from consumption of the locally-produced food and animal products grown in the mine-like soils of Old Yutanga. Moreover, the Se-enriched coal used for cooking was also an additional source of Se. Consequently, residents were required to move to a neighboring village site called New Yutanga, a region with low Se content in the soil. At this new location, crops and animals were produced, and consumed by the residents. Soil, plants, animals, blood and hair samples were again collected and analyzed for Se, as well as for specific Se biomarkers in the blood plasma. Results showed lower Se concentrations in all food products and reductions in the plasma biomarkers related to Se content in blood. In conclusion, moving the residents from Old Yutanga to New Yutanga, a region with low Se content in the soil, was an effective strategy for reducing selenosis in villagers living in a naturally-rich Se area of Enshi China.

Technical Abstract: In 1963, selenosis occurred in residents living in Old Yutangba, a village located in northwestern Enshi, China. This part of China has high levels of natural-occurring selenium (Se) in rock/soil deposits. Because Se toxicity symptoms were observed in many residents of Old Yutangba, they were required to migrate to a new area of Yutangba (New Yutangba) to avoid high levels of Se exposure. To evaluate dietary Se intake by Old Yutangba residents after moving to New Yutangba, samples were randomly collected by University of Science and Technology of China in New Yutangba and analyzed for Se in soils, food products, as well as samples in hair, blood serum and plasma from local residents who previously had lived in Old Yutangba for at least 3 years. Results showed that the mean total and bioavailable Se concentrations were 1753.6±742.8 µg/kg and 47.4±29.9 µg/kg, respectively, in soil samples. In food products, the Se concentrations were as follows: tubers (23.8±9.6 µg/kg FW), grains (rice: 62.9±45.1 µg/kg DW), vegetables (170.6±157.4 µg/kg FW) and animal meats (331.4±48.2 µg/kg DW). Based on these concentrations, the estimated daily Se intake in New Yutangba was estimated to be at a safe level of 63.2 ±39.8 µg/day, which was slightly higher than the recommended dietary intake for Se in Chinese adults (60 µg/day). The mean Se concentrations in hair and plasma samples were 549.7±165.2 µg/kg (n=60) and 98.4±32.1 µg/L (n=58), respectively. The activities of selenium-dependent antioxidant enzymes of total glutathione peroxidase (GPx) and superoxide dismutase (SOD) were 169.2±57.0 U/mg FW (n=58) and 55.9±43.3 µg/L (n=58), respectively, while biomarkers plasma Sepp1 level (selenoprotein P, encoded by SEPP1 gene) was 344.9±118.0 µg/L (n=58). These results clearly showed that by relocating the residents to New Yuangba, consumption of local and market foods containing lower Se concentration, could effectively (as indicated by biomarker responses) reduce the risk of high Se exposure from natural food products produced in Old Yutangba.