Causes
Common causes of fluorosis include inhalation of fluoride dusts/fumes by workers in industry, use of coal as an indoor fuel source (a common practice in China), consumption of fluoride from drinking water (naturally occurring levels of fluoride in excess of the CDC recommended safe levels), and consumption of fluoride from the drinking of tea, particularly brick tea. Skeletal fluorosis can be caused by cryolite (Na3AlF6, sodium hexafluoroaluminate).
In India, the most common cause of fluorosis is fluoride-laden water derived from deep bore wells. Over half of ground water sources in India have fluoride above recommended levels.
In Tibet, excessive consumption of poor-quality pu-erh tea is reported to cause fluorosis.
Fluorosis can also occur as a result of volcanic activity. The 1783 eruption of the Laki volcano in Iceland is estimated to have killed approximately 25% of the Icelandic population, and 50–80% of livestock, as a result of fluorosis and sulfur dioxide gases. The 1693 eruption of Hekla also led to fatalities of both people and livestock under similar conditions.
Read more about this topic: Skeletal Fluorosis