Environmental Epidemic Characteristics of Coal- Burning Endemic Fluorosis and the Safety Threshold of Coal Fluoride in China

Data on coal-burning endemic fluorosis throughout China and on the exposure-response relationship between concentrations of fluoride determined in coal samples and the prevalence of dental fluorosis reported from 17 representative surveillance stations in Southwest China were used to estimate the safety threshold for coal fluoride. Coal-burning endemic fluorosis occurs mainly in the mountainous areas of this part of China, where the prevalence of the disease is closely linked to geochemical parameters of the local environment. In these regions the incidence of dental fluorosis has a significant positive correlation with the concentration of fluoride in coal. The safety threshold of coal fluoride is estimated to be 190 mg/kg by the criterion of 0% incidence of dental fluorosis.