Water fluoridation
Health and dental organizations worldwide have endorsed its safety and effectiveness. Its use began in 1945, following studies of children in a region where higher levels of fluoride occur naturally in the water. Further research showed that moderate fluoridation prevents tooth decay.
Water fluoridation controversy
Fluoridation began during a time of great optimism and faith in science and experts (the 1950s and 1960s), but even then, the public frequently objected. Opponents drew on distrust of experts and unease about medicine and science. Controversies include disputes over fluoridation's benefits and the strength of the evidence basis for these benefits, the difficulty of identifying harms, legal issues over whether water fluoride is a medicine, and the ethics of mass intervention.