Skeletal fluorosis is a bone disease exclusively caused by excessive consumption of fluoride. In advanced cases, skeletal fluorosis causes pain and damage to bones and joints. Advanced cases usually involve about ten times the normal amount of fluoride.

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, and consumption of fluoride from the drinking of tea, particularly brick tea.

In India, the most common cause of fluorosis is fluoride-laden water derived from deep bore wells.

Epidemiology

In some areas, skeletal fluorosis is endemic. While fluorosis is most severe and widespread in the two largest countries - India and China - UNICEF estimates that "fluorosis is endemic in at least 25 countries across the globe. The total number of people affected is not known, but a conservative estimate would number in the tens of millions.

Skeletal fluorosis in China and India

The World Health Organization recently estimated that 2.7 million people in China have the crippling form of skeletal fluorosis. In India, 17 of its 32 states have been identified as "endemic" areas, with an estimated 66 million people at risk and 6 million people seriously afflicted.

According to scientific surveys, skeletal fluorosis in India and China occurs when the fluoride concentration in water exceeds 1 part per million (ppm), and has been found to occur in communities with only 0.7 part per million.

The Chinese government now considers any water supply containing over 1 ppm fluoride a risk for skeletal fluorosis.

Skeletal fluorosis in the United States

In the United States, an average of 1 ppm of fluoride is intentionally added to water supplies for water fluoridation. The Maximum Contaminant Level (MCL), as established by the US Environmental Protection Agency, is 4 ppm. In 2006, the U.S. National Academy of Sciences concluded that this MCL is not sufficiently protective against fluorosis, and should be lowered. Symptomatic skeletal fluorosis is almost unknown in the U.S., with about a dozen cases reported.

Skeletal fluorosis phases

Osteosclerotic phase	Ash concentration (mgF/kg)	Symptoms and signs
Normal Bone	500 to 1,000	Normal
Preclinical Phase	3,500 to 5,500	Asymptomatic; slight radiographically-detectable increases in bone mass
Clinical Phase I	6,000 to 7,000	Sporadic pain; stiffness of joints; osteosclerosis of pelvis and vertebral spine
Clinical Phase II	7,500 to 9,000	Chronic joint pain; arthritic symptoms; slight calcification of ligaments' increased osteosclerosis and cancellous bones; with/without osteoporosis of long bones
Phase III: Crippling Fluorosis	8,400	Limitation of joint movement; calcification of ligaments of neck vertebral column; crippling deformities of the spine and major joints; muscle wasting; neurological defects/compression of spinal cord

References

External links

• - An excellent overview of the disease. Authors: Dr. D. Raja Reddy and Dr. Srikanth Deme
• http://www.fluoridation.com/skeletal.htm
• Skeletal fluorosis in India
• with the reference for Hypothyroidism in fluoride poisoning.