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
The first large fluoridation controversy occurred in Wisconsin in 1950. Fluoridation opponents questioned the ethics, safety, and efficacy of fluoridation. New Zealand was the second country to fluoridate, and similar controversies arose there. Fears about fluoride were likely exacerbated by the reputation of fluoride compounds as insect poisons and by early literature which tended to use terms such as "toxic" and "low grade chronic fluoride poisoning" to describe mottling from consumption of 6 mg/L of fluoride prior to tooth eruption, a level of consumption not expected to occur under controlled fluoridation. When voted upon, the outcomes tend to be negative, and thus fluoridation has had a history of gaining through administrative orders in North America.