We use data from the nationally representative (United States) High School and Beyond cohort, characterize fluoride exposure from drinking water across adolescence, adjust for confounders, and observe cognitive test performance in both secondary school and at age ~60. We find that children exposed to recommended levels of fluoride in drinking water exhibit modestly better cognition in secondary school, an advantage that is smaller and no longer statistically significant at age ~60.

West Island mayors say that Montreal’s consultation on water fluoridation was triggered by a 2020 petition submitted by Ray Coelho — a man they describe as a “far-right” extremist.

Fluoride toothpaste is efficacious in preventing dental caries, but its effectiveness depends on frequency of use by persons or their caregivers. In contrast, water fluoridation reaches all residents of communities and generally is not dependent on individual behavior.

Although early studies focused mostly on children, water fluoridation also is effective in preventing dental caries among adults. Fluoridation reduces enamel caries in adults by 20%-40% (16) and prevents caries on the exposed root surfaces of teeth, a condition that particularly affects older adults.

Water fluoridation is especially beneficial for communities of low socioeconomic status (18). These communities have a disproportionate burden of dental caries and have less access than higher income communities to dental-care services and other sources of fluoride. Water fluoridation may help reduce such dental health disparities.

Based on 2013 estimated costs ($324 million), net savings (savings minus costs) from fluoridation systems were estimated to be $6,469 million and the estimated return on investment, 20.0.

To see the potential impact of stopping water fluoridation, Yancoskie points to locations that have been previously studied.

"The two areas that were studied were Juneau, Alaska, and Alberta, Canada, and when they removed that fluoride, the rates of cavities increased dramatically in the children of those populations," he said.

"Seventy years of research, thousands of studies and the experience of more than 210 million Americans tell us that water fluoridation is effective in preventing cavities and is safe for children and adults," according to the American Dental Association.