Fluoride in groundwater

Fluoride is an ion of the chemical element fluorine which belongs to the halogen group.

Fluoride has a significant mitigating effect against dental caries if the concentration is approximately 1 mg/l. However, continuing consumption of higher concentrations can cause dental fluorosis and in extreme cases even skeletal fluorosis. High fluoride concentrations are especially critical in developing countries, largely because of lack of suitable infrastructure for treatment (http://www.wateraid.org).

Fluoride is a common constituent of groundwater. Natural sources are connected to various types of rocks and to volcanic activity. Agricultural (use of phosphatic fertilizers) and industrial activities (clays used in ceramic industries or burning of coals) also contribute to high fluoride concentrations in groundwater.

IGRAC produced a report on the probability of occurrence of excessive concentrations of Fluoride at the global scale.
Most of the report can also be read online.