Fluoride occurs naturally in drinking water, especially well water, but the concentrations are generally low in public water supplies. In some countries, such as the US, Canada, UK, Australia and Ireland, fluoride is commonly added to the public water supply at around 0.7mg per litre to prevent tooth decay. The World Health Organization guideline for fluoride in drinking water is 1.5mg per litre.
Given the concern that fluoride in drinking water might affect children’s intelligence, the addition of this mineral to drinking water has become controversial. Consensus among researchers about the precise nature of the link between fluoridation and intelligence is lacking and the existing evidence is widely debated.
