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Comment by agentultra | Hacker News Reader

That’s going to go poorly. A Canadian city removed fluoride from water in 2011 and reversed that decision 10 years later. There’s hard data on the effects and they’re not good [0].

[0] https://www.npr.org/2024/12/13/nx-s1-5224138/calgary-removed...

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The study [1] that's based on seems pretty typical, and is precisely what drives skepticism towards these policies. The differences for permanent teeth were not significant. The paper claimed this may be because "7-year-olds have not had the time to accumulate enough permanent dentition caries experience for differences to have become apparent." The differences in temporary teeth had a deft (decay, extracted, filled teeth) of 66.1% in Calgary (no fluoride) and 54.3% in Edmonton (fluoridated).

So you're looking at a small positive improvements in dental outcomes, for what may be a permanent decline to IQ. That's obviously not a trade I think anybody would make, so the real issue is not whether or not it improves dental outcomes but whether it's having measurable effects on IQ as we have seen in other studies. [2] I don't understand why a study operating in good faith wouldn't also pursue this question in unison, or in fact as the primary question. I think relatively few people outright doubt the dental benefits of fluoride, but rather are concerned about the cost we may pay for such.

[1] - https://onlinelibrary.wiley.com/doi/full/10.1111/cdoe.12685

[2] - https://ntp.niehs.nih.gov/whatwestudy/assessments/noncancer/...

The most ridiculous part is that we have an alternative way to apply fluoride without intaking it. It's called toothpaste. But for some reason people act like Utah is banning vaccine.

Using toothpaste with fluoride can be effective when used regularly as part of dental hygiene. What percentage of the population is going to do this? I've encountered grade school children who have never owned a toothbrush.

Can you answer your own question?

In the 2nd study that shows correlation between fluoride and lower IQ in children, the water had twice as much fluoride as the recommended amount in the US (1.5 mg/L vs 0.7 mg/L).

The only reason for lack of concrete statements on the 0.7 level was a lack of data, owing largely to US political culture (1.5 is the World Health Organization 'safe' limit). Not long ago fluoride stuff was considered a 'conspiracy theory' which greatly deters meaningful scientific research on the topic. This is in part because of social reasons (most people don't want to be perceived as 'fringe') and in part because it results in funding for such research drying up. For that matter even IQ studies themselves are borderline given the US political culture.

So for instance of the 19 low risk-of-bias studies, exactly 0 came from the US. 10 were in China, 3 were in Mexico, 2 in Canada, 3 in India, and 1 in Iran. 18 of those 19 studies found a significant reduction in IQ that corresponds strongly with increases in fluoride (the outlier was in Mexico). With the current administration we'll certainly be seeing funding for such studies in the US and so there should be much more high quality data on the 0.7 level forthcoming. But in general this is a major problem that needs solving. Exploring the breadths of science, including the fringes, should not require an activist political administration.

There are natural experiments where the correlation between IQ and lower amounts of fluoride can be studied. For example in Israel, until 2014, the fluoride level was 0.8-1.0 mg/L depending on the region but starting in 2014 water is no longer fluoridated (naturally occurring fluoride level is in the 0.1-0.3 mg/L range for the vast majority of the population) so the data should be there, it's just a matter of collecting it. Some countries can provide data for the opposite natural experiment (adding fluoride in recent years).

To me, using the 1.5 mg/L doesn't tell anything about lower levels but it does make me interested in seeing such study whereas before I'd have just dismissed it.

For that matter even IQ studies themselves are borderline given the US political culture.

This isn't remotely true; it's just something people say on message boards.

This might have been a viable argument a decade ago because these rules were implicit and not explicit. But as of 2022 they've become explicit. [1] IQ is distributed dramatically differently in different groups, which makes it difficult to meaningfully study in the US because, as Nature now puts it, "Although academic freedom is fundamental, it is not unbounded... Science has for too long been complicit in perpetuating structural inequalities and discrimination in society..."

This is why meaningful studies on IQ are basically dead in the US and similarly why we were one of last countries to confirm the absolutely critical reversal of the Flynn Effect. I think the political tide started to turn really hard after the decades long Minnesota Transracial Adoption Study ended up definitively proving the opposite of what it intended. [2]

[1] - https://www.nature.com/articles/s41562-022-01443-2

[2] - https://en.wikipedia.org/wiki/Minnesota_Transracial_Adoption...

You should tell that to all the researchers publishing work in this field!

Most working in the field in the US are doing so only due to an effort to undermine it, not study it. Otherwise - they aren't getting published, at least not by the traditionally prestigious journals. Here [1] is a search in reverse chronological order from Nature for studies with the terms IQ and intelligence. The exact demarcation mark is difficult to find, but I do think 1996 is a reasonable indicator. In any case the difference is plainly visible.

I particularly like their trend of publishing editorials with ledes like, "We are leading Nature on a journey to help decolonize research and forge a path towards restorative justice and reconciliation." How can that not make you cringe? People are going to look back at this as the equal but opposite of phrenology. Or perhaps we've had our own Al-Ghazali [2] moment and people will look back at this era as an inflection point in science shifting from one culture to another.

[1] - https://www.nature.com/search?q=iq+intelligence&journal=natu...

[2] - https://en.wikipedia.org/wiki/Al-Ghazali

So the problem isn't that the science is being done, it's that the results are challenging conclusions you've already drawn? At least we're clear on what the issue is. The work I'm talking about has nothing about "decolonization" in it, but lots on GWAS and population stratification statistics.

On the contrary, I think the one and only thing that really enabled such widespread advances in science over the past few centuries was the same thing that initially enabled such for the Greeks - people were able to pursue things with near to no limitations, no taboo, no dogma. And it seems that perhaps such things are inherently liminal in nature. The Greeks would then go to on to execute perhaps the greatest thinker in humanity's history for wrongthink, and we ourselves are already well into the times of where not only is there taboo and dogma, but it's even overtly stated.

When you get into population stratification issues you're already again flirting with taboo depending on what is being studied. So yeah - low sample sized, poorly controlled, correlation exclusive GWAS studies are the gold standard in genetics publications. I'm so completely surprised that such, alongside the rusty hacksaw that's CRISPR, failed to live up to even a zillionth of their 'potential'.

Explain the point you just tried to make re: stratification.

Any characteristic being studied whose presence or absence would be seen as socially negative sense is going to be walking a very fine line if it turns out to be associated (or not) with certain subgroups because then you're right back to, in Nature's terms "[being] complicit in perpetuating structural inequalities and discrimination in society."

Unfortunately, hard data is not acceptable. This is how it works for the current administration:

All previous data is ignored because of political reasons.

Teeth to slowly rot in heads.

Sometime in the 2030s, local voters will notice they have very bad teeth.

Locals will debate if adding fluoride is going to make teeth great again.

I don't think it's about hard data and optimization of health, but rather bodily autonomy.

I'm sure there are plenty of chemicals that could be forcibly put in the drinking supply that, based on current scient, would be beneficial for the public. But I would still be skeptical. Sell me these substances in my food or toothpaste, but don't put it in my drinking water by default.

It's also worth noting about 3% of western Europe has fluorinated so let's not pretend like this is unprecedented

Many places in Europe have high levels of fluoride in their water naturally. In fact many of them are likely getting far too much fluoride.

Also realistically, if people cared about bodily autonomy cars would've been banned immediately thanks to the amount of particulates and local pollution produced causing far more adverse health effects.

If a state wants to ban cars it should be free to do so. I think the benefits outweigh the costs and no one would choose to live there.

Also important to note no one is banning flouride. They're preventing it from being put in the drinking water. The equivalent would be if cars were distributed upon arriving to the state.

The state is taking the rights away from the municipalities. Why not leave it up to the local people? No one was forcing local towns to fluoridate their water.

But municipalities that chose to do so would be taking the choice away from each individual.

I don't know enough to form an opinion about whether Utah's new policy is good or bad, but it is clearly on the side of individual freedom. (of course that's not the only concern)

I would say that it's not on the side of individual freedom but the will of the state. It's easier to build a local coalition than a state wide one. Democracy has costs but they're usually lessened when you're going down to the local levels. Sure an individual may not get to choose everything (such as zoning laws) but zoning laws are best managed by the municipality and not at the state nor federal level.

Imagine if 70% of Salt Lake City wants this but can't because of people living hundreds of miles away. Not sure if that's a huge win.

> Imagine if 70% of Salt Lake City wants this but can't because of people living hundreds of miles away. Not sure if that's a huge win.

That 70% can use floride toothpaste or mouthwash. What happens to the 30% who don't want it in your scenario?

Democracies have costs. Unless you expect 100% of people to agree on everything, then you have to accept that the minority should accept certain outcomes. The smaller the group that chooses, the better the majority. The more likely that you personally will be able to make a change.

Local is better than State. State is better than Federal. If this was going from the federal level to the state, I would agree that it's a win for personal liberty. Unfortunately it's local going to the state level. If a water district of 100,000 people all want this, they simply can't do it. It doesn't seem fair that people who won't be impacted get to decide.

> Local is better than State. State is better than Federal.

I agree. When issues require collective action, it should be decided at the smallest capable level.

In this case, the smallest capable level is the individual. To extend your comparison: individual is better than local.

This _isn't_ an issue that requires collective action; people can treat their own teeth with fluoride or take fluoride supplements.

I assume you hold the same consistent viewpoint on say, Abortion, correct?

Yes, municipality is better than state which is better than federal government. The same viewpoint with gun laws, taxation, regulation, etc. It's easier for me to move a few miles to find like minded people than it is for me to move hundreds of miles to leave a state or thousands to leave the my country.

Personally I see states as an artifact of the 20th century. Why can't municipalities govern themselves? Why shouldn't my city be able to leave my state and join another. States made sense before the internet and communication was difficult. Now they're just a middle man without a lot of value.

If eastern towns of California don't want to be grouped together with San Francisco or Los Angeles: why should they be forced to be? Because someone in the 18th or 19th century determined it?

The equivalent would be if I'm forced to have a government funded road with cars just past my front yard.

Is one due the right to potable water at a tap at their home? Or is purified water a service offered by the government as one source of many available to the us population?

Are you not allowed to pay for bottled water instead of paying your local utility for drinking water?

The bodily autonomy argument seems bad to me because you are buying water from the government when you could buy water from any other source instead.

Is the argument that the government water is too convenient and so it should be unfiltered? Who is to say that filtering out poop is not infringing on my right to consume unfiltered water?

Fluoride was introduced late enough in Zimbabwe that many of my childhood adults easily remembered life before it. There were many horror stories about the general state of teeth prior.

That being said, your dentist can apply fluoride to your teeth (boggles the mind why insurance won't pay the $50), and flouride toothpaste is still much more common than not. It's probably not needed in the water supply for dental purposes.

That being said, what are the other fringe benefits: such as microbe control?

The city of Houston has stopped adding fluoride to water but allows natural fluoride levels to exist[0]. We are going on year 6 and the only thing we have noticed is harder water.

There is probably more nuance to both stories tho.

[0] https://houstonherald.com/2018/11/lindsey-and-long-win-count...

All the evidence in that article is based on what a politician thinks. "And I think another meta study came out also".

The actual high quality evidence shows that water fluorination has minimal impact on tooth health in 2025: https://www.cochrane.org/news/water-fluoridation-less-effect...

I was thinking of this study:

https://onlinelibrary.wiley.com/doi/full/10.1111/cdoe.12215

Perhaps more could be done. The situation is complex because of several compounding factors for sure. There are European countries that have no water fluoridation and better oral health outcomes than in North America.

Regardless, there’s 10 years where a city in North America turned off water fluoridation and we have results of that decision to study.

I'm skimming the results, but it looks like adult teeth had less cavities when they turned the fluoride off...and that was not observed in Edmonton where they left the fluoride on the whole time.

"For all tooth surfaces among permanent teeth (Table 1a), there was a statistically significant decrease in Calgary, for the overall mean DMFS, which was not observed in Edmonton."

Based on their data, you could argue that fluoride increases cavities in adults... I'm not making that argument. I agree with you in that I think confounders are at play and the difference attributed to fluorinated water isn't as large.

People will use this study to take about the rampant tooth decay in Calgary, ignoring that there is roughly as much decay in Edmonton which had the fluoride on the whole time.

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