Coal burning induced endemic fluorosis in China

Wide-spread coal-burning in China is caused by indoor combustion of high fluoride(F)-containing coal. The incidence of fluorosis increases with increase in the F content of coal. Indoor airborne F of fluorosis-afflicted areas exists mainly in a gaseous form (SiF4 and HF) with some co-existing aerosol forms. Gaseous F contributes about 40 - 84% of total inorganic F emission. Total airborne inorganic F was in the range of 11 - 155 mu g/m(3), several times higher than the National Hygienic Standards. Total F intake by adults in disease areas was found to be about 10 mg/day as compared to 0.8 mg/day in nondisease areas.