Data on Coal-burning – Endemic
Fluorosis Throughout China – In these regions the incidence of dental
fluorosis has a significant positive correlation
with the concentration of fluoride in coal.
106 Fluoride Vol. 36 No. 2 106-112 2003 Research Report For Correspondence: Prof Wuyi Wang, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. E-mail: email@example.com
ENVIRONMENTAL EPIDEMIC CHARACTERISTICS OF COALBURNING ENDEMIC FLUOROSIS AND THE SAFETY THRESHOLD OF COAL FLUORIDE IN CHINA
Yonghua Li, Wuyi Wang, a Linsheng Yang, Hairong Li Beijing, China
SUMMARY: 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.
Fluorine (F), the most electronegative and reactive of the halogens, is a common chemical element in the earth’s crust in combined form. F concentrations in rocks and soils are well documented, but data on the F concentration in coal are relatively limited.
1-4 ) Swaine reported the total F concentration in coal ranges from 20 to 500 mg/kg.
5) Statistical data indicate that the mean concentration of F in coal worldwide is 80 mg/kg, but in China it is 200 mg/kg.
6) In the mountainous areas of Southwest China, it is even higher— up to 3106 mg/kg in local coal.
7) Fluoride in coal can be released into the ambient environment as atmospheric F, waterborne F, and residue F during mining, handling, and combustion.