The cause of endemic fluorosis in western Guizhou Province, Southwest China

The endemic fluorosis in western Guizhou Province, southwest China is usually attributed to a high-fluorine content in Late Permian coals. This study found that the average fluorine content in 50 coal channel samples from western Guizhou Province ranges from 16.6 to 500 μg/g, with an average of 83.1 μg/g, which is close to the world average (80 μg/g) and that of Chinese coals (82 μg/g). Additionally, the fluorine content of drinking water and fresh corn is too low to lead to fluorosis in western Guizhou Province. However, the clay used as an additive for coal-burning and as a binder in briquette-making by local residents has a very high content of fluorine, ranging from 100.8 to 2455.7 μg/g, with an average of 1027.6 μg/g. The endemic fluorosis is likely caused by fluorine in the clay. Therefore, in areas where unhealthy traditional coal-burning habits and customs are kept and furnaces without chimneys are used, the more clay used for a coal-burning additive and as a binder for briquettes, the more serious the fluorosis problem is.