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Fluoride in drinking water has no effect on IQ or brain function, long-term study shows (twin-cities.umn.edu)
submitted 7 months ago by to c/science@mander.xyz
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Study.

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.
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[–] 1 point 7 months ago (8 children)

Eh the first major study in fluoride, the Grand Rapids study would never hold up to today’s standards. It was not a blind study and cavity detection is subjective.

Also drinking water is a poor way to deliver fluoride. The mechanism of action requires physical contact with your teeth to work. Toothpaste and mouthwash would be a better option and reduce consumption. To my knowledge, there hasn’t been a modern large scale study conducted looking into different delivery methods. We do have some evidence comparing countries that don’t fluoridate but still have low cavity rates.

And while rare, fluoride allergies do exist.

It can also be difficult to dose.

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  • [–] 5 points 7 months ago (7 children)

    the first major study in fluoride, the Grand Rapids study would never hold up to today’s standards. It was not a blind study and cavity detection is subjective.

    There has been many more studies on fluoride, none of which have shown that that the low concentrations of fluoride added to drinking water has any negative health effect. Not just the one, always check multiple sources!

    Also drinking water is a poor way to deliver fluoride

    It depends on the area you're dealing with. In some countries, it's more cost effective to put fluoride in the water supply, while in others, fluoride toothpastes are more effective. In Germany, they put fluoride in iodized salt!

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  • [–] -1 points 7 months ago* (6 children)

    There has been many more studies on fluoride, none of which have shown that that the low concentrations of fluoride added to drinking water has any negative health effect.

    Again, there have not been any randomized control trials testing the efficacy of fluoride in drinking water compared to other delivery methods.

    It depends on the area you're dealing with. In some countries, it's more cost effective to put fluoride in the water supply, while in others, fluoride toothpastes are more effective. In Germany, they put fluoride in iodized salt!

    Did you just not read my comment? The reason isn’t cost, it’s not that expensive to add fluoride.

    The reason is we wouldn’t be adding anything to drinking water if there were better alternatives. If we started again with today’s standards, no scientist would recommend fluoridated drinking water.

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  • [–] 4 points 7 months ago* (last edited 7 months ago) (5 children)

    The reason isn’t cost, it’s not that expensive to add fluoride.

    In many countries, particularly in developing nations, fluoridation of water is too expensive (since you need the infrastructure for it), and fluoride toothpastes are preferred instead. But in industrialised countries, where infrastructure for managing the water supply already exists, fluoridation of water is more effective. Places where tap water is more readily available (like the U.S., much of Western Europe, Canada, Ireland, etc.) will also be more likely to adopt the fluoridation of water.

    The reason is we wouldn’t be adding anything to drinking water if there were better alternatives. If we started again with today’s standards, no scientist would recommend fluoridated drinking water.

    Fluoridation of water still helps to prevent tooth decay, and in regions where it is cost-effective, it is a great benefit to public health! Of course, fluoride toothpastes are great, but it's not the best solution for everywhere.

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  • [–] 1 point 7 months ago (4 children)

    much of Western Europe, etc.) will also be more likely to adopt the fluoridation of water.

    Citation needed.

    Of course, fluoride toothpastes are great, but it's not the best solution for everywhere.

    Why not? Or more specifically, why is this insufficient in the US? Are there studies comparing the efficacies?

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  • [–] 3 points 7 months ago (3 children)

    much of Western Europe

    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

    Why not? Or more specifically, why is this insufficient in the US?

    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.

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  • [–] 1 point 7 months ago (2 children)

    why can't we have both?

    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.

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  • [–] 0 points 7 months ago (1 child)

    I don't understand why this is such an issue. The water isn't fluoridated where I live and there is no resulting epidemic of dental caries. It's not a problem in developed nations.

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  • [–] 2 points 7 months ago

    What’s happened is that there have been tons of conspiracy theorist claims against water fluoridation. These claims are not based on any scientific evidence.

    However, valid criticism has also been suppressed and in the process fewer studies have been conducted. The topic has been highly politicized, especially recently.

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