Inadequate or excess fluoride
Fluoride intake has both beneficial effects – in reducing the incidence of dental caries – and
negative effects – in causing tooth enamel and skeletal fluorosis following prolonged high
exposure. The ranges of intakes producing these opposing effects are not far apart.
It is estimated that caries of the permanent teeth is the most prevalent of all conditions
assessed, with 2.4 billion people globally suffering from caries of permanent teeth and
486 million children from caries of primary teeth. Public health actions are needed to
provide sufficient fluoride intake in areas where this is lacking, so as to minimize tooth
decay. This can be done through drinking-water fluoridation or, when this is not possible,
through salt or milk fluoridation or use of dental care products containing fluoride, and
by advocating a low-sugar diet.
Excessive fluoride intake usually occurs through the consumption of groundwater
naturally rich in fluoride, particularly in warm climates where water consumption is
greater, or where high-fluoride water is used in food preparation or irrigation of crops.
Such exposure may lead to dental fluorosis or crippling skeletal fluorosis, which is
associated with osteosclerosis, calcification of tendons and ligaments, and bone
deformities. While the global prevalence of dental and skeletal fluorosis is not entirely
clear, it is estimated that excessive fluoride concentrations in drinking-water have
caused tens of millions of dental and skeletal fluorosis cases worldwide over a range
of years. Although removal of excessive fluoride from drinking-water may be difficult
and expensive, low-cost solutions that can be applied at a local level do exist.
WHO has published guidance to help communities control fluoride exposures to
establish the important balance between caries prevention and protection against
adverse effects. However, risk mitigation measures implemented should also take
into consideration local contexts and sensitivities.