The controversy occurs mainly in English-speaking countries, as Continental Europe does not practice water fluoridation. Instead, fluoride is added to most table salt in Europe.

Those opposed argue that water fluoridation imposes ethical issues, may cause serious health problems, is not effective enough to justify the costs, and has a dosage that cannot be precisely controlled.

The weight of the scientific evidence have found that at the dosage recommended for water fluoridation, the only clear adverse effect is dental fluorosis, which can alter the appearance of children’s teeth during tooth development.

This effect is mildly cosmetic and is unlikely to represent any real effect on public health. Despite opponents’ concerns, water fluoridation has been effective at reducing cavities in both children and adults.