The study, published in PNAS, examined Wisconsin state testing records, archival information about when Wisconsin cities began to fluoridate their water, and data from the Wisconsin Longitudinal Study, which has followed a random sample of 10,317 high school seniors from 1957 through 2026. Key findings include:
- There is no evidence supporting a connection between community water fluoridation and children’s IQ.
- There is also no evidence supporting a connection between community water fluoridation and cognitive functioning at various points later in life.
- Findings confirm evidence published in previous research which also used a national sample, but considered school achievement test scores instead of actual IQ scores.



Citation needed.
Why not? Or more specifically, why is this insufficient in the US? Are there studies comparing the efficacies?
Correction added to my comment, it looks like that for most of Western Europe, fluoridation in water is not common. That was a mistake and I acknowledge that, and I have edited my comment to reflect that.
However, Ireland and England both implement the fluoridation of water. In particular, 73% of Ireland’s population drinks fluoridised water
https://ukhsa.blog.gov.uk/2016/04/13/water-fluoridation-what-it-is-and-how-it-helps-dental-health/ (UK) https://pmc.ncbi.nlm.nih.gov/articles/PMC4081215/ (Ireland)
Additionally, so does Canada:
https://www.canada.ca/en/services/health/publications/healthy-living/fluoride-factsheet.html https://www.canada.ca/en/public-health/services/publications/healthy-living/community-water-fluoridation-across-canada.html
Well, for one, tap water is readily available in the U.S., making fluoride super accessible to a large portion of the population! Also, fluoride toothpastes exist in the U.S. too, why can’t we have both? Both are effective at preventing tooth decay, perhaps toothpaste moreso (and there are studies that show that, you can easily search for yourself I think), but both help to prevent cavities.
Because drinking water is a basic need and should not be medicated when it’s not even a great way to apply the medicine.
Note that while the risk of issues from proper dosing is low. Improper dosing can and does occur. Sandy City, Hooper Bay, Richmond to list a few. When you improperly dose community water you’re affecting everyone using the water.
If toothpaste or mouthwash was improperly dosed, it would be mostly spit out and the risk is minimized while also maximizing exposure to the enamel.