I initially dismissed it as the same category of stupid as anti-vax beliefs, but it turns out that there are a decent amount of good studies showing a link between fluoride in water and (slightly) lower IQ when pregnant mothers ingest the fluoride. Note that there is no significant effect after birth.
The idea is to remove fluoride from water and advise pregnant women to use fluoride-free toothpaste.
Everyone else can get enough fluoride from modern toothpastes, or regular dentist treatments.
The logic is that fluoride in tap water made sense in the era before toothpaste had it, but now it is “overmedicating” a vulnerable fraction of the population.
In the actual research the main "risk" posed by flouridated water is actually fluorosis. This causes minerals in your enamel to be replaced with flouride which can cause them to be brittle in the long term. It's pretty uncommon but the thought is that now that flouride toothpaste are commonplace, the benefit of flouridated water is also way less. Which changes the calculus.
A not insignificant number of researchers are advocating for the view that flouridating water just isn't worth it anymore and the (slight) risk of flourosis is more significant than the (slight) benefit of decreased dental caries.
Children are the main group that benefits from fluoride in water because the fluoride helps strengthen teeth as they form. Lack of fluoride increases childhood cavities, leading to decreased academic performance.
This was a real problem in the San Jose school district until recently. They started fluoridation of water in the last ten years, and were the biggest US city that didn’t fluoridate. The evidence of the above is clear according to SJ dentists I have talked to.
The National Toxicology Program recently completed a fairly substantial meta study and concluded that "for every 1 mg/L increase in urinary fluoride, there is a decrease of 1.63 IQ points in children.". [1] This is also relevant to OP since it's not just pregnant women at risk from excessive fluoridation but also children. For now it seems that adults are, somewhat oddly, unaffected.
> It is important to note that there were insufficient data to determine if the low fluoride level of 0.7 mg/L currently recommended for U.S. community water supplies has a negative effect on children’s IQ.
Yeah, note the measurement is in urine. So there are two separate issues. Determining whether fluoride is damaging to IQ, and then whether the levels in water can drive this. The former is way easier to evaluate than the latter. The reason comes from that study's intro pargraphs:
---
"Since 1945, the use of fluoride has been a successful public health initiative for reducing dental cavities and improving general oral health of adults and children. There is a concern, however, that some pregnant women and children may be getting more fluoride than they need because they now get fluoride from many sources including treated public water, water-added foods and beverages, teas, toothpaste, floss, and mouthwash, and the combined total intake of fluoride may exceed safe amounts."
---
So the issue is trying to isolate the exact amount and source of fluoride people are getting. And that probably has no answer because it's going to vary dependent on how much fluoridated water somebody drinks, the rest of their diet, their other dental hygiene composition, and more. So levels that would be safe for one percent of the population, will be dangerous for another percent of it.
Fluorosis is very common afaik. My dentist told me I have it: slightly whiter patches on my teeth. Then he showed me his own fluorosis. It actually is stronger than the old enamel.
Does the study not literally refute the claim that fluoride's negative impact on IQ is lacking in evidence, contrary to the original claim? What exactly do you think needs to be updated?
the original refutation was "fluoride in the drinking water concentrations is proven safe and it doesn't affect brains". Your study does not show that IQ is effected at concentrations that are being added to water supplies. Just because X can result from Y levels of some substance does't mean X results from Y-n concentrations.
> the original refutation was "fluoride in the drinking water concentrations is proven safe and it doesn't affect brains".
No, this is the original claim:
> but it turns out that there are a decent amount of good studies showing a link between fluoride in water and (slightly) lower IQ when pregnant mothers ingest the fluoride.
Then the parent replied that this IQ link is lacking evidence, which it's not, per the meta-analysis I cited.
For fluoride measured in water, associations remained inverse when exposed groups were restricted to less than 4 mg/L or less than 2 mg/L but not when restricted to less than 1.5 mg/L
There were limited data and uncertainty in the dose-response association between fluoride exposure and children’s IQ when fluoride exposure was estimated by drinking water alone at concentrations less than 1.5 mg/L.
The meta analysis you linked gets the strongest results in areas of the world with outstandingly high levels of fluoride and other elements in the ground water .. water with so many additives it rings like a bell when tapped with a hammer (okay, that's an embellishment).
You can’t win. Freedom, IQ, precious bodily fluids. There’s no end to the nonsense.
My city started fluoridating a few years ago. The crazy was off the chart, they’re still active. NYC has fluoridated for 60 years, you’d think someone would have figured out that the entire city is dumber.
But being serious if it’s relatively low and the negative effects only occur during pregnancy it’s not that easy to measure it.
Obviously there is no conclusive evidence (even if the studies from China seem somewhat credible) but IMHO even if the likelihood of this being true is e.g. only 5-10%, risk of a population wide loss of 1-2 IQ points seems like a massively too high price to pay just to slightly reduce cavity rates.
Also dismissing all credible (albeit weak) scientific evidence out of hand just because crazy people hold similar beliefs is a about as stupid as what they are doing..
Well one issue with your snark here is that IQs within the country are going down, and nobody really knows why. [1]
The Flynn Effect was the observation that real IQ scores were increasing over time. But sometime around 1990 this seems to have stopped in pretty much the entire developed world, including the US. I'm not implying that this is solely due to fluoridation, though it's certainly a plausible contributing factor. But as for your snark about 'someone would have figured out people are getting dumber' - well, they have, and we don't know why.
> IQs within the country are going down, and nobody really knows why.
I’m no expert, but I have seen the public education system attacked and defunded for decades, at home and abroad. Even libraries are being shut down in places with enough anti-intellectual sentiment. This goes much deeper than the fluoride in water.
If you can point to IQ values of New York specifically, going down more significantly starting with the introduction of fluoride into the water system, then you might have something there.
Until then, policy discussions like this will continue to take focus from the things that actually have an impact on IQ, like public education, healthcare/nutrition, and poverty.
Education stuff is more of a political talking point than reality. In reality US education spending per student has continually increased and is always near the top of the world. As of 2019 we're 4th in the world for spending on elementary/secondary spending $15,500 per student contrasted against $11,300 for the OECD average. [1] Of course we are having increasingly poor educational outcomes in spite of spending more, more, and more. So if there is a causal relationship between the reversal of the Flynn Effect and poor educational outcomes, it would seem much more likely that the former is causing the latter.
And I'm certain one could trivially dig up data correlating the decline of IQ in New York to fluoridation. The Flynn Effect reversal began in the 90s, and New York began fluoridating their water in 1965, so there's an excellent age correlation there. But that correlation does not necessarily mean causation. What matters are more controlled studies determining definitively whether fluoride is intellectually harmful by using fluoride levels in urine to control for various confounding variables (people in the same regions getting fluoride from multiple sources, consuming more/less products with fluoride, etc). And we do have those studies, and the answer is yes it is.
That certainly doesn't mean it's the sole cause for the reversal of the Flynn Effect as its seen across the developed world, and many countries do not add fluoride to their water. But it is likely a contributing factor. In recent decades we have begun moving far faster than we're capable of evaluating the consequences of, and long-term consequences may well be stacking from multiple sources of mistakes.
> Education stuff is more of a political talking point than reality. In reality US education spending per student has continually increased and is always near the top of the world.
This is disingenuous, and itself a political talking point.
> In reality US education spending per student has continually increased and is always near the top of the world.
It is much more nuanced than “money in equals IQ out”.
Where does the money end up? Not in classrooms, unfortunately.
What is the average ratio of teachers to students? Is this number going up, up, up?
Now do counselors, nurses, etc.
How much are teachers spending out of pocket for classroom supplies? Has this number gone down, down, down?
Yes, it does end up in classrooms. Feel free to look up the metrics you're talking about. Here [1], for instance, is the student to teacher ratio which has continued to decline dramatically over the years. And this difference becomes even more stark when contrasted against many of the countries, particularly in Asia, with substantially greater educational outcomes with far less in the way of every resource.
By "most" metrics the US should be having phenomenal educational outcomes. The one variable that's not controlled for is the quality of students. Also, I put "most" in quotes because it's a weasel word - to my knowledge we outperform on every single typical educational metric, except result.
Flouridation of drinking water does not happen in the entire developed world, though.
And lower IQ scores don't necessarily say much about pure intelligence directly, a worsening education system could also contribute and that's not exactly far fetched. And your linked source says:
> The steepest slopes occurred for ages 18–22 and lower levels of education
Absolutely. And nutrition in general, the internet, and a large number of other factors. Starting around the 90s the world started changing far faster than we were able to measure the consequences of in many different domains. That's even when the rates of autism and other mental disorders also started to skyrocket. That's why I think it's a viable contributing factor rather than the alpha and omega.
But it's relevant here because most people don't know that general intelligence levels (so far as IQ can measure) have begun to decrease, to the point that the GP here was overtly mocking the mere possibility of such as a [implied] practical impossibility.
Do you think bodily autonomy is absolute? Your comments seem to imply that bodily autonomy is the only relevant thing to consider when discussing patient care. The world doesn't work that way. Believe it or not, a doctor won't amputate a limb when you show up with a runny nose even if you insist that that's the procedure you want. Search up the 4 principles of biomedical ethics if you want to learn more about the factors that influence doctors' ethical decisions.
Or do you mean that your opinion should trump that of any doctor or expert in any field when the issue pertains to your person? If that's the case, I wonder why you choose to participate in society at all, given that you're uncomfortable with the idea that other people might know more than you.
No. When decisions I take could affect others, that can, in a limited way, justify overriding bodily autonomy. E.g. preventing someone with an infectious disease from spreading it by quarantining them. Or when they can't make their own decisions, e.g. if they're children, suffering dementia, or are unconscious and time is critical.
> Believe it or not, a doctor won't amputate a limb
I struggle to understand how this is a reasonable, much less charitable, interpretation of my words. Bodily autonomy does not include commanding others. But people can refuse care, even when it is medically sound. Except in very limited circumstances, doctors may not force procedures or medicine on unwilling patients.
> Or do you mean that your opinion should trump that of any doctor or expert in any field when the issue pertains to your person? If that's the case, I wonder why you choose to participate in society at all, given that you're uncomfortable with the idea that other people might know more than you.
One does not at all follow from the other. Experts in the field will tell me excessive sweets are bad for me (and I believe them) - should they get to put a block my credit card so it cannot be used to buy unhealthy snacks, only healthy food?
I have humored your post, now please explain to me: How does believing people have a right to refuse medical treatment imply I am uncomfortable with others being more knowledgeable?
Not just regular toxic chemicals, either, through the is plenty of that. Quite a bit of radiation too.
And companies that adulterate, misrepresent and obfuscate what they put in food as well. No-one is putting corn syrup or brominated vegetable oil in food with any intention other than money money money.
In fact, if I were an evil subgenius and really actively wanted to damage the IQs of the nation for some nefarious purpose, and it has to be substance-based, I'd avoid things with annoying oversight like public drinking water and vaccines and focus on food and pollution as a vector. If challenged, I just say "why do you hate my freedom to make a profit and provide jobs". Sure, the FDA and EPA exist, but even then you can get away with far, far more in those areas. Food wise, HFCS, BVO, etc, pollution wise, almost everything to with plastics or polymers, oil, coal, gas the list goes on and on.
That's just not true. Most of the studies simply compared areas with different amounts of natural fluoride in their local water supply, and applied some basic statistics comparing dental health. There have also been some A/B studies possible in areas that stopped or started using fluoride in their water.
Multiple such studies have been done, globally, over many decades.
There is limited modern evidence (ie. in a world where everyone is brushing their teeth with fluoride toothpaste) of some reduction in tooth decay in children. There were no studies on adults that met the review criteria.
Overall it seems like we just don't really know how much impact CWF currently has.
Fluoridated toothpaste says not to swallow because it contains much higher concentrations of fluoride than drinking water. If you ingest too much toothpaste, it can cause your teeth to get blotchy: https://en.wikipedia.org/wiki/Dental_fluorosis
Yup, but even for fluoride gels it says explicitly not to swallow. One because fluoride is toxic when concentrated, two because it needs to be on your teeth, not inside your belly.
Once ingested, the fluoride has a systemic affect on teeth before they erupt, incorporating into the matrix of developing teeth to increase the mineralization content and decrease the solubility of enamel. [1]
7mg/L? Where the heck did you get that figure?
The correct value is a tenth of that: 0.7 milligrams per Liter (mg/L)
The limit is 2mg/L, and that's only found in places with naturally occurring high levels of flouride.
The people of Flint, MI were (and some still are!) forced to drink bottled water for years when their water was contaminated with lead.
When you drink from publicly supplied water, you accept risks that can be much worse than fluoride in your water. If you want to avoid that, you need to procure your own drinking water.
There isn’t any! GP doesn’t have that authority! Well done!
On the other hand, the society you live in probably has some sort of document establishing who does have the authority, and how it devolves to the actual policy-makers. Google “$YOUR_LOCATION government” and you’ll have some good starting points. If you’re lucky, you might even get to participate in the process; “$YOUR_LOCATION elections” will give you good pointers in that case.
> but now it is “overmedicating” a vulnerable fraction of the population.
Makes sense, but the intention also is that many people do not brush their teeth, or at least do not brush them as often as they should, and so fluoride is added to drinking water to compensate so people's teeth don't start to fall out at an alarming rate.
Sadly, an alarming percentage of Americans don't drink water. I’ve spoken to way too many people who think water tastes wrong because it’s not sweet enough.
It’s heartbreaking, but not surprising. When you’re dealing with limited resources, constant stress, and often living in areas where healthy options are harder to access or more expensive, sugary drinks can feel like an affordable comfort. Instead of judging SNAP recipients, we should be looking at the systems that make soda more accessible than clean, appealing
, and fresh food.
> I judge them the same way I judge anyone that drinks that crap: harshly. Don't tell others they shouldn't judge people for their misdeeds.
Good job ignoring absolutely everything in the comment except the part that offended you. Nothing more American than having a hard-on for being judgemental and then defending the right instead of actually trying to solve the underlying problem.
Are SNAP recipients not allowed to enjoy a soda at all? I really don't understand the problem with this. Society acts like signing up for SNAP involves signing a contract to lose 100 pounds and only eat iceberg lettuce or something.
Americans seem to love to gatekeep what the poor are allowed to have or not have.
They have this image of the Welfare Queen driving a pink Cadillac to cash her welfare checks at the liquor store.
It seems that no matter how desperately destitute someone might be,
there's a person who will point at something they have,
whether it's a tent to sleep in under a bridge (a gift from an organization providing assistance to the houseless),
a bicycle that's their only means of transportation,
or a garden planted on public property,
and say "they can't be that poor if they have that!
When someone lives off of public benefit, there's a sense in which the public can have an interest in how the money is used -- its use should correlate with its intent.
That's why SNAP money is restricted to particular categories. So caring about how it's spent is already a foregone conclusion, and rightly so.
If someone wants to spend money however they like, they'll have to earn it themselves. Even inherited money carries a sense of obligation to honor the family with how it's used (like not blowing it all in a week of lavish partying in Vegas, as an extreme example).
If an individual spends 10% of their SNAP benefits on soda, they’ve spent about ~$30 over a month on it, which is ten 20fl oz drinks. People drinking a bit more than a gallon of soda per month only supports the notion that they can subsist on that without any water if you believe that they categorically have some sort of exceptional unhuman biology.
Well, it's true that water has zero calories and is neutral tasting. It's not filling to any degree, and milk will give you a lot more of what your body needs.
Water is great for hydration without filling you otherwise. Like, say you need to drink a lot of fluid because you are really active, you would probably get sick of milk pretty quickly.
But anyway, in most cases, the fact that drinking milk doubles as a source of food is clearly a benefit. It's hard to explain a common behavior by reference to a rare circumstance.
The idea of sports drinks is that you can drink them without getting water poisoning. This is only a concern if you need a lot of water because you've been sweating a lot, but I thought that was the scenario you were pointing to.
Probably because the overwhelming majority of countries chlorinates their water to various degrees because they don't have the exceptional plumbing quality needed to otherwise guarantee potability.
Countries where the tap water is drinkable without chlorination have quality that exceeds bottled water, and it might even be sourced from the same aquifers.
When travelling where? The blanket statement here just doesn't work. Every major area has very different water in the tap. A lot of the bottled water is just tap water from another region.
When traveling by vehicle (pickup truck for me) I've thrown in a 5 gallon cooler of water from home. It was so nice to want to drink water because it was my own good well water that tastes like I'm used to.
When I had to fly to NY for work I felt like I couldn't get water anywhere that was worth drinking.
Where in New York? If NYC, this sounds insane to me, because New York municipal water is objectively speaking among the purest (if not the purest) in the country.
San Francisco tap water is almost as good. It was better before they started mixing reclaimed water into it, though I’ve either gotten used to the new taste or they’ve fixed the treatment process.
I question this as a bad take or a data-point of one, because NYC water is the best of Upstate water.
I’ve travelled and lived across the country during my high school and college years; and I’ve travelled my
extensively within Upstate very (Adirondacks, Catskills, and Finger Lakes) and the taste of local water is the first thing I notice.
Bad building pipes aside, I have not tasted any water that exceeds NYC’s tap water in taste.
I’m not the only person who’s expressed this, and guests from other regions have also admitted the same consistently over the years.
It can vary much more closely than that. I moved from one town to another 12 miles away, and the tap water in the new town tasted horrible compared to my old town's tap.
I'm pretty sure that no amount of fluoridated water is going to save you if you do not brush your teeth.
Even if the fluoride somehow manages to overcome all that and prevent you from getting cavities, the gum disease will eventually cause all your teeth to fall out.
Important sentence is "..or at least not as often as they should" :)
I have no doubt most people brush their teeth in one capacity or another, but do you really think 98% of people brush them regularly and sufficiently? I reckon that drops down quite a few double digits at that point, and since we're talking about populations here that's quite a lot of people.
The levels of fluoridation in order to cause difference in IQ as I understand it, from the Chinese studies, suggest that basically the effect if true occurs at around 2x+ the concentration found in supplemented water supplies.
My understanding also is that if you’re a dentist wanting to get rich, move somewhere that has unfluoridated water.
2x is basically no safe margin for something like water. Of course you can question the quality of the study, but if it's actually 2x, fluoride in tap water should be treated like lead pipes.
So if your training and double your water intake your basically lowering you IQ? (according to the Chinese studies) I wonder the method this uses.. has anyone looked at dementia rates in high fluoride areas.. Particularly in people with high water intake?
There is also a host of things we use water for from cooking to preserving, distilling and cooling.. i wonder if any of these things could concentrate the fluoride.
Also since fluoride has a lower boiling point any studies tracked what breathing in fluoride gas over long periods cause?
2x is honestly pretty small. I would expect the amount required to drop IQ to be larger by an order of magnitude or more to conclude that fluoridating water is totally safe.
> I initially dismissed it as the same category of stupid as anti-vax beliefs
Dismissing things out of hand like this is a category of stupid in itself.
Look at the current research, listen to people who devoted their careers to studying this, make up your own mind. If you're on HN, then you're qualified enough to at least figure out who the genuine experts are and read what they recommend.
Putting any science-based debate into a "category" to dismiss is turning yourself into one of the stupid people.
This is bad advice that no one could possibly follow.
> Look at the current research, listen to people who devoted their careers to studying this, make up your own mind.
Do you honestly do this with every single belief you have? Even every single controversial belief? Have you looked, yourself, into whether the world is flat? Whether the 9/11 conspiracy theories are true? Whether crop circles were created by aliens? These are all absurd conspiracy theories, but I assume most people don't know the "up to date" research on any of them, or what people who have "devote their careers" to research them say.
And those are incredibly common and well known to be false theories.
You have to take some things on faith to at least some degree - though to be clear, by "on faith" I mean "on faith of people you trust", which should really start with professional scientists etc. Also, it's totally fine to just say "I have no actual idea" about most things, and just go with what your current understanding of the status-quo position is.
> Have you looked, yourself, into whether the world is flat? Whether the 9/11 conspiracy theories are true? Whether crop circles were created by aliens?
> Everyone else can get enough fluoride from modern toothpastes, or regular dentist treatments.
The advantage of putting it in water is that it ensures all children get it, not just the children whose parents can and do make sure they brush their teeth and go to the dentist.
Agree, my biggest issue is often where they source the fluoride and whether they test it. We found out in my (liberal) hometown that they were actually sourcing some derivative which has no human studies.
Given that everyone gets enough in toothpaste I just don’t see the reason to keep doing it, too much can go wrong. It’s kind of a strange mass medication that I’m not sure the government needs to be involved in.
> The idea is to remove fluoride from water and advise pregnant women to use fluoride-free toothpaste.
What most people don't understand here are the levels of fluoride being ingested. You can very easily remove all fluoride from your water with a relatively cheap RO system. But the recommendation to use "fluoride-free toothpaste" is just plain misinformation.
The reason is that you don't eat toothpaste. And even when adults ingest small amounts of toothpaste, again, the amount of fluoride is basically beyond negligible. Fluoride can both be applied to teeth as a varnish and/or consumed in drinking water. Using a flouride-free toothpaste can oftentimes do more damage than good because of SLS in those alternatives and because those alternatives often have abrasives that do far more harm than good. It's amazing people will recommend a product that may likely be worse because they have no domain expertise. So, yes, people should talk to their Dentist about these things and ask questions of them vs the Internet.
Really the downside to removing fluoride from city water is that low income families will be worse off with respect to dental related issues compared to more well off families that spend time instilling dental hygiene and preventative care for their kids. As you mentioned most people who have decent oral hygiene get enough flouride.
Where we live we have well water. Fluoride in the water isn't a concern, and if it was in our drinking water it generally wouldn't be consumed because of the water filtration anyway.
My anecdotal experience says that using fluride-free biomine toothpaste makes my tooth highly sensitive than using a good ol' Colgate. Now, I use it only twice or thrice per month randomly.
The idea is to remove fluoride from water and advise pregnant women to use fluoride-free toothpaste.
Everyone else can get enough fluoride from modern toothpastes, or regular dentist treatments.
The logic is that fluoride in tap water made sense in the era before toothpaste had it, but now it is “overmedicating” a vulnerable fraction of the population.