Spatial Analysis and Biogeochemical Cycles: A Comparative Study of Kashin-Beck Disease Villages and Non-disease Villages in Linzhou County, Tibet

This study investigated Linzhou County in Tibet, which currently hosts the most serious outbreak of Kashin-Beck disease(KBD) in China. This study uses the geographical detector(GeoDetector) algorithm to measure the influences that several risk factors have on KBD prevalence and validates the spatial analysis results with environmental chemistry. Based on a comprehensive examination of 10 potentially related spatial factors and an environmental chemistry analysis of the soil-water-grain-human biogeochemical cycle in the local KBD and non-KBD villages, four main conclusions are drawn.(1) KBD in Linzhou County is a consequence of multiple interrelated environmental factors, of which the most important controlling factor is the stratum factor.(2) The concentrations of selenium(Se) in all environmental media(soil, water, and food) and human tissue in the KBD villages in Linzhou County are lower than those of the non-KBD villages.(3) The intake of Se and chromium(Cr) by local residents is seriously insufficient, especially the average daily dose by ingestion(ADD) for Se in the KBD village, which is only about 4% of the World Health Organization(WHO) recommended lower limit for adult elemental intake.(4) We speculate that the main cause for the local KBD outbreak is a lack of Se in the stratum. This absence leads to a serious Se deficiency in the local population through ecosystem migration and transformation, which will eventually lead to an endemic biogeochemical Se deficiency.