The Source, Pathway, and Preventive Measures of Endemic Fluorosis in Guizhou

The content of fluorine in coal, clay used for coal combustion, mixed fuel of coal and clay, corn, and chili from families of the endemic fluorosis in Zhijin County, Guizhou, was determined using the pyrohydrolysis/fluorine ion-selective electrode method. The results showed the average content of fluorine in samples is 237.1 μg/g, 2261.9 μg/g, 827.9 μg/g, 1418.8 μg/g, and 110.1 μg/g, respectively. The content of fluorine in corn and chili are about 1400 and 73 times higher than that of the permitted level of fluorine in foods of the Chinese Standard. The clay used for coal combustions is the main fluorine source of the endemic fluorosis. In addition to occurring in apatite and hornblende, fluorine is closely related to the adsorption of illite and mixed-layer clay minerals of smectite and illite. About eighty percent of fluorine was emitted out during the combustion of mixed fuel of coal and clay minerals. Besides the technologies of fluorine fixation and decreation, changes in the living habits of the residents, for example, the chili washed by water, the corn husked before it was processed into corn powder, will remove a certain content of fluorine absorbed on the corn husk and will play a important role in endemic fluorosis prevention.