Fluorosis

Fluorosis is an abnormal condition caused by excessive intake of fluorine, as from fluoridated drinking water, characterized chiefly by mottling of the teeth.
Moderate level chronic exposure (above 1.5 mg/l of water) is quite common.

Long-term ingestion of large amounts can lead to potentially severe skeletal problems (skeletal fluorosis). The early symptoms of skeletal fluorosis include stiffness and pain in the joints. In severe case, the bone structure may change and ligaments may calcify, with resulting impairment of muscles and pain. Acute high-level exposure to fluoride causes immediate effects of abdominal pain, excessive saliva, nausea and vomiting. Seizures and muscle spasm may also occur.

It is believed that fluorosis affects millions of people around the world, but as regards dental fluorosis the very mild forms are the most frequent. Waters with high levels of fluoride content are mostly found at the foot of high mountains and in areas where the sea has made geological deposits. Known fluoride belt on land include: one that stretches from Syria through Jordan, Egypt, Libya, Algeria, Sudan and Kenya, and another that stretches from Turkey through Iraq, Iran, Afghanistan, India, northern Thailand and China.

Click here to learn for more information about waterborne diseases, dimension of the problem, transmission, prevention.

Sources:
http://www.who.int/water_sanitation_health/diseases/fluorosis/en/
Picture:
http://images.google.com/images?q=fluorosis&hl=en&lr=&rls=GGLD,GGLD:2005-12,GGLD:en&start=0&sa=N