Fluorine : human health risks

Fluorine (fluoride) is beneficial to human health in low concentration but toxic in excess. One of the main exposure routes is via drinking water. It is unproven whether fluoride is essential for health but numerous studies have demonstrated that low concentrations in drinking water (0-0.5 mg L-1) are associated with increased dental caries (tooth decay) rates whereas contents of 0.5-1.5 mg L-1 are protective against the disease. As a result, fluoride is widely used in dental products and water fluoridation programs have been implemented in many countries. However, exposure to higher concentrations via drinking water (> 1.5 mg L-1), some teas and fluoride-contaminated salt and the burning of high-fluoride fuels can cause deformities of the hard tissues, namely dental and skeletal fluorosis. Dental fluorosis is an irregular calcification disorder of the enamel-forming process during childhood leading to pitted, stained and eroded teeth. In contrast, skeletal fluorosis is a crippling disease caused by over-mineralization of the bones and joints as a result of longer term exposure to high fluoride intakes. It is estimated that these diseases affect over 70 million people globally, limiting their ability to work and support their families. Hence the need for better understanding of environmental exposure to help mitigate these health outcomes.