Fluorine Toxicity

Most of the body’s fluorine (F) is contained in bones and teeth. Fluoride (the ionic form of fluorine) is widely distributed in nature. The main source of fluoride is fluoridated drinking water.

Excess fluorine can accumulate in teeth and bones, causing fluorosis. Permanent teeth that develop during high fluoride intake are most likely to be affected; exposure must be much greater to affect deciduous teeth. High fluoride content (>10 parts per million) in drinking water is the most common cause of fluorosis. In the United States, the recommended water fluoride level is 0.7 parts per million.

The earliest signs of fluorine toxicity are

• Chalky-white, irregularly distributed patches on the surface of the enamel

These patches become stained yellow or brown, producing a characteristic mottled appearance. Severe toxicity weakens the enamel, pitting its surface. Bony changes, including osteosclerosis, exostoses of the spine, and genu valgum, can develop but only in adults after prolonged high intake of fluoride.

Though controversial, there is evidence that prolonged exposure to high levels of fluoride in drinking water (far higher than in normal fluoridated drinking water) is associated with lower IQ scores, though this association was not found at levels below 1.5 parts per million (1).

Diagnosis of fluorine toxicity is based on symptoms. Tests to measure fluoride serum and urine levels may be available..

Treatment of fluorine toxicity involves reducing fluoride intake; eg, in areas with high fluoride water levels, patients should not drink fluoridated water or take fluoride supplements. Children should always be told not to swallow fluoridated toothpastes.