Endemic Fluorosis caused by indoor air pollution of Fluorine and high-Fluorine clay?

Baoshan Zheng 1*, Daishe Wu 1, Binbin Wang 1, Xiaojing Liu 1, Aimin Wang 2 , Yonghua Wu 2 , Hongshu Chen 2 , Robert B. Finkelman 3

• The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry , The Chinese Academy of Sciences, Guiyang , 550002, P.R. China
• Center of disease control in Zhijin County , Guizhou Province, P.R. China
• US Geological Survey MS 956 National Center, 12201 Sunrise Valley Drive Reston , VA 20192 , U.S.A.

Fluorosis caused by indoor air pollution of Fluorine is the only type of endemic disease that still lacks an effective method of prevention and control. By the end of 2000, there were 33,901 people living in indoor environments contaminated by Fluorine, including 17,695 people with dental fluorosis, and 1,465 people with skeletal fluorosis. Guizhou is the province that suffers the most from indoor coal-combustion type fluorosis. 28.11% of the total population of Guizhou Province , 14,489 people , including 9,910 people with dental fluorosis, are living in indoor coal-combustion type fluorosis areas in Guizhou Province (NSB, 2000).

During the period of 1980-1984, the following results were proved by authors :
1. There is no positive relationship between fluorine concentration in foodstuff and in soils and rocks.
2. Absorbing fluorine from indoor combustion formed high fluorine content foodstuffs. Fluorine emitted from combustion was acid-soluble fluorine.
3. Of the two factors that induced fluorosis, the method used to dry and store foodstuff was more important than the concentration of fluorine in coal. If there was indoor coal combustion without any protection, and if the main foodstuff of local people was corn, even if the fluorine concentration of coal was only dozens of mg/kg, fluorosis would occur.

A recent study investigated endemic fluorosis as well as the fluorine concentration in environmental samples. In indoor coal-combustion type fluorosis area, local clay was mixed with coal for indoor combustion. The authors determined that there are two key steps in the procedure of indoor transition of fluorine: (1) Indoor wet corn and vegetables strongly absorbed fluorine from indoor air; and (2) Fluorine strongly accumulated in clay, which was mixed with coal powder for combustion. Therefore, with the increasing of percentage of clay in the clay mixed coal powder as well as corn in foodstuff, the incidence of fluorosis will be increased.