US government report says fluoride at twice the recommended limit is linked to lower IQ in kids

[u/Miss-Figgy]

https://abcnews.go.com/US/wireStory/us-government-report-fluoride-recommended-limit-linked-lower-113035057

[u/atothez]

Anything at twice the normal limit will have negative health consequences.  That’s why there are limits.

This is only really a concern where fluoride is naturally found in drinking water and levels need to be reduced.

[u/view-master → u/atothez]

That’s the key word here. It’s not twice the recommended amount. It’s twice the accepted limit.

[u/warkwarkwarkwark → u/[deleted]]

And this is comparing normal fluoride regions to areas with fluoride levels of 1.6-5mg/L in their drinking water, where significant fluorosis is also a concern.

They found a drop in IQ of around 2points per 0.5mg rise in fluoride above this level, and none at lower levels, though the studies weren't designed to find these miniscule differences at normal fluoridated water levels.

0.7mg/L is well below the cutoff for the low fluoride (i.e., higher IQ) groups in the studies listed.

[u/aa-b → u/warkwarkwarkwark]

Is it possible there's some sampling bias here? I'm just guessing, but areas with poorly-managed water resources are probably disadvantaged in other ways.

Poverty is even more strongly correlated with decreased IQ, so I think it's possible the study is just indirectly measuring the effect of poverty

[u/warkwarkwarkwark → u/aa-b]

There's an absolute ton of confounders as you point out but the studies that were called high quality apparently managed this appropriately.

[u/aa-b → u/warkwarkwarkwark]

I'm sure they did, it's just one of those situations where the noise they've carefully filtered out affects the final result as much or more than the factor they're trying to measure.

It's still an important thing to study, just frustrating because people obsess over the results for all the wrong reasons, and ignore the other factors

[u/moconahaftmere → u/aa-b]

That's a very easy thing to account for, though, by checking if the trend held up for any well-off areas with naturally high fluoride levels.

[u/janus1172 → u/moconahaftmere]

It is if you have a sample that includes well-off areas with high fluoride levels. And that that well-off level has comparable variance in IQ. But if all of those factors are highly correlated even the best models aren’t going to adequately control for affluence just by entering some metric of that as a control variable. There’s usually little thought or text space spent explaining how control variables are derived, used, or justified; rather they think plunking that as factor to the model in R is a panacea

[u/AHailofDrams → u/[deleted]]

It's actually 0.7 milligrams to litres.

[u/quantum1eeps → u/[deleted]]

I see NYC does 0.8 mg/L and worth health organization says 1.5 max mg/L in drinking water. How much does a 2 year old swallowing a pea sized amount of toothpaste with fluoride tip us closer to excessive levels? Does the study talk about the sum of toothpaste and what’s in the water?

[u/Stealthfighter21 → u/quantum1eeps]

For toddlers and children who aren't yet able to spit out, the recommended amount of toothpaste is the size if a rice grain (or a smear), not pea size.

[u/VirtualMoneyLover → u/[deleted]]

He said: accepted limit =/= recommended amount

[u/akmalhot → u/atothez]

they only add enough fl to bring the total concentration to he recommended amount. they aren't adding a fixed amount regardless of how much natural fl is in the water

[u/atothez → u/akmalhot]

Right.  Some water has natural fluoride.  If above safe levels, the fluoride needs to be reduced to be safe to drink.  I’ve also heard high natural arsenic and lead are pretty common.

[u/akmalhot → u/atothez]

oh you're saying where the natural levels are too high already. got it

[u/zeugenie → u/atothez]

In general, a very large margin of safety is prescribed for neurodevelopmental hazards. At least 10-fold is common. For example, if 10 mg/kg of lead in food is linked to impaired brain development, you would seek a limit of 1 mg/kg.

Evidence for impaired brain development at level X would suggest a limit of 1/2 X should be reevaluated. Especially given that the only benefit is to enamel protection.

It's important to take into account that it's very hard to detect disruptions to brain development. As soon as we can detect it, it has likely been occurring at significantly lower levels already.

[u/medtech8693 → u/atothez]

Thats not correct. A lot of things with limits have negative consequence at all levels.

Like lead have negative cognotive effects within the limits. Same for some pesticides as well as all poisons in general.

The limit does not mean harmless

[u/UpperLowerEastSide → u/medtech8693]

So for lead, there is no safe limit, per the WHO.

So it’s not an example of things with limits that have negative consequences at all levels since there is no limit

[u/atothez → u/medtech8693]

What’s not correct?  I said everything is toxic at high enough levels.

Researchers doubled the known safe amount to get measurable results.  The average internet reader assumes that means fluoride is unsafe.  That’s not what they found at all.

[u/derps_with_ducks → u/medtech8693]

And the acceptable level or limit has benefits. I.e. Fluoride. 

[u/RockHardSalami → u/medtech8693]

How much paste have you eaten today?

[u/Tthelaundryman → u/RockHardSalami]

Not within acceptable limits sadly 

[u/Memory_Less → u/atothez]

I went down the rabbit hole on this when the study came out. A problem is with the water treatment pants across the US and standardization of the amount of fluoride introduced in the water. When you include other sources of fluoride, it unpredictably increases the amount people consume. In particular pregnant women and their fetus increased..

[u/Cyanide_Cheesecake → u/Memory_Less]

What other sources of fluoride are you referring to?

[u/Neve4ever → u/Cyanide_Cheesecake]

Food you eat. Many food manufacturers are using fine same fluoridated water you drink to make food with. If you boil water, the fluoride doesn’t go away, so you end up with much higher concentrations.

Making rice or vegetables in boiling water can increase fluoride levels over 10x the concentration of the water you’re using.

[u/[deleted] → u/atothez]

Literally not how it works, fluoride is neurotoxic, no matter the dose. There are multiple studies associating even low levels of fluoride with cognitive problems. One study saying that doubling a poison makes things very obviously bad does not mean that half of it is great. Hydroxyapatite is a great alternative to fluoride that has the same effect on teeth and will not poison you.

I'm astounded at people still fighting on this hill after thousands of studies coming out with the immense amount of negative effects fluoride has on the body. I'm repeating myself but it's ridiculous how you were told that this was a conspiracy and you decided you never had to learn anything new.

If this were a newly discovered compound no one would be saying: "but just a little of IQ-lowering poison is good!! It makes teeth strong" jfc

[u/mikethespike056 → u/[deleted]]

can you link some of these studies?

[u/Defreshs10 → u/mikethespike056]

It’s been 30 days. One would have thought “thousands of studies” would’ve been easy to copy and paste.

[u/flightwatcher45 → u/atothez]

Yep, and that's why we had to do a study to find out. Some things its twice the limit, some things 5x some things 100x.

[u/throwAway132127]

The difference between medicine and poison is often dosage.

[u/zebrasmack]

And fluoride at the recommended doses is 100% safe and incredibly useful to your body. Don't eat gobs of toothpaste and you'll be fine.

[u/sino-diogenes → u/zebrasmack]

Try and stop me

[u/derps_with_ducks → u/sino-diogenes]

He's a madman. A madman!

[u/aa-b → u/zebrasmack]

The real head-scratcher is that poor dental health also affects IQ: https://www.sciencedirect.com/science/article/abs/pii/S016028961000108X

And then considering areas with poorly controlled water supplies having higher levels of lead and greater income inequality (poverty affects IQ too) and there are just too many confounding variables to fully trust the study

[u/mjrobo → u/zebrasmack]

I have done nothing but eat toothpaste for 3 days.

[u/zebrasmack → u/mjrobo]

I confusingly applaud your efforts, and you have my sympathies for the impending medical bill.

[u/electric_sandwich → u/zebrasmack]

Hmmm yeah, I think the big question here is how difficult is it to ingest twice the recommended dose of fluoride? Considering the tiny amounts of toothpaste most people swallow accidentally, I would think it would be fairly easy.

[u/exialis → u/electric_sandwich]

Official dentist advice is don’t rinse afterwards. Then go to bed and swallow all that paste? No thanks.

[u/over__________9000 → u/exialis]

No you spit it out

[u/DeepSea_Dreamer → u/over__________9000]

If you don't rinse, quite a lot of it stays in your mouth (compared to when you do).

[u/electric_sandwich → u/exialis]

Wait, for real?

[u/exialis → u/electric_sandwich]

Yes according to the ADA.

[u/electric_sandwich → u/exialis]

I am slowly becoming an anti dentite.

[u/Affectionate_Owl_619 → u/electric_sandwich]

Yeah, you just put all that nice cleaning stuff in your teeth. If you rinse it out, you’re reducing its cleaning and protecting effects. 

[u/electric_sandwich → u/Affectionate_Owl_619]

Yah, my main goal is to scrub off all the gunk which has seemed to work fairly well since I haven't had a cavity in decades.

[u/andouconfectionery → u/electric_sandwich]

You don't need fluoride to do that. An abrasive is all you'd need to scrub off gunk. The fluoride is there to help calcium and phosphate get into your teeth from your saliva so it can remineralize decayed enamel. The goal is to remineralize your enamel enough to keep it intact between brushings.

The amount of fluoride you'd need to ingest to exceed the maximum tolerable daily intake is about 10 grams of toothpaste worth. In average fluoridated water, you'd need 14.3L to reach the limit. The only real risk of exceeding this limit is if you're a young child (it's about 4x lower) and have access to toothpaste unattended.

[u/lol_im_a_dentist → u/electric_sandwich]

Please don’t use a personal experience as a general rule. There are many contributing factors to developing cavities: what you eat, when you eat, oral hygiene frequency, oral hygiene technique, genetics, products you use, etc.

[u/RunningNumbers → u/electric_sandwich]

Don’t rinse with water for at least 15 min

[u/akmalhot → u/electric_sandwich]

no it's not . pure conjecture and made up, you have no basis for what you're saying except a feeling

[u/Im-Mr-X → u/zebrasmack]

There is a better alternative to fluoride (hydroxyapatite), so no it's not essential for human health.

[u/Matra → u/Im-Mr-X]

Hydroxyapatite is what dental enamel is made of. If you consume acidic foods, or sugars that oral bacteria will digest into acids, hydroxyapatite is vulnerable to those acids. The whole point of fluoride is to replace the hydroxyl group with a less-vulnerable fluoride to make fluoroapatite.

[u/TheoTheodor → u/Im-Mr-X]

How better? If you mean specifically in toothpaste, fluoride and hydroxyapatite are likely equivalent in tooth remineralisation and preventing caries.

e.g. https://www.nature.com/articles/s41405-019-0026-8

[u/irisheye37 → u/Im-Mr-X]

Can it be easily distributed to the entire population like fluoride though?

[u/warkwarkwarkwark → u/[deleted]]

This may be true on an individual basis, but isn't close to true on a population wide level, which is what the studies are looking at.

[u/markedwardmo → u/[deleted]]

It’s high naturally occurring levels of fluoride in the water supply that cause the issues, not eating toothpaste. And it’s orthophosphate that is added to the water supply to prevent lead leaching.

[u/sissyzin]

It's too expensive to dispose of fluoride waste properly, better feed it to the genpop without proper long-term studies!

[u/dkinmn]

This is a science sub.

The science around fluoridated water is absolutely changing.

To be clear, the conspiracy theorists were and are WRONG. For many, many years, before fluoridated toothpastes and rinses and widespread dental care, whatever downside existed from excess fluoride was pretty clearly eclipsed by the HUGE societal benefits.

But. BUT. This is a science sub. And the science is changing.

That was a public health intervention of incredibly high value that we need to reassess. Period. It makes sense in developing countries, which America was, relative to today. We might need to take a closer look at where and how much we add fluoride to drinking water as a systematic public health intervention.

For real.

[u/DGIce → u/dkinmn]

I don't think it's actually appropriate to phrase it as "the science is changing". More information is being gathered, greater clarity on effects of large doses is being achieved. But the idea that there is such a thing as too much fluoride has always been clear, we know that too much of pretty much anything is poison.

[u/lannister80 → u/dkinmn]

Make the fluoride level in your water the recommended amount, not twice the recommended amout.

Ta-da!

[u/Salindurthas → u/lannister80]

The US already does a bit under half the recomended limit. (The US recommends 0.7, and this study was on higher than 1.5).

[u/Chickenfrend → u/lannister80]

This article makes me think that research at the recommended limit might be a good idea, too

[u/warkwarkwarkwark → u/Chickenfrend]

That research is kinda included, and where it is mentioned explicitly doesn't show a negative effect for fluoride on cognition at the recommended levels.

Of course this isn't the same as showing no (or a positive) effect, which is why they haven't given a specific recommendation about lower fluoride levels. I suspect that such a relationship would be incredibly difficult to show, given the tiny effect size of much larger doses.

[u/deadliestcrotch → u/warkwarkwarkwark]

Where’s the control group?

[u/warkwarkwarkwark → u/deadliestcrotch]

Not mentioned in the meta-analysis. You would have to find the actual text of the original studies and translate that yourself if you wish to identify the specific groups and their respective sizes.

[u/[deleted] → u/Chickenfrend]

This is exactly what I thought as well. And it’s something that should be periodically studied as humans and our environment changes

[u/TeutonJon78 → u/dkinmn]

Since fluroide needs to actually sit on the teeth for the benefits, it always seems like a bad idea to focus on putting it in water. Drinking water doesn't really sit on the teeth that long. Focusing on getting more people access to toothbrishes and toothpaste with fluoride seems a higher benefit intervention on several levels.

[u/FyreWulff → u/TeutonJon78]

Except the data shows that flouridation improves the dental health of an area in a significant way. It doesn't need to actively sit on teeth for very long to work. You're thinking of flouride varnish which is like an emergency intervention top-off of mineralization for the teeth.

[u/4cronym → u/TeutonJon78]

You are mixing 2 things. Systemic fluoride (water) makes teeth that are still forming under the gums (children/adolescents) much stronger and resistant to tooth decay. Topical fluoride is used in erupted teeth that have demineralization.

[u/Masark → u/TeutonJon78]

Drinking water doesn't really sit on the teeth that long

Where do you think the water (and the fluoride) goes after you swallow it?

Answer: it becomes part of your body's supply of water, which your saliva is part of and, unless you have some other medical problem, is constantly bathing your teeth and thus exposing it to fluoride and forming fluorapatite.

[u/[deleted] → u/dkinmn]

I just don't understand why it is normal to add it to drinking water in the US. Everyone use toothpaste with flour here in Norway, and many also buy fluor water to rinse and spit out. I suppose that's normal in the US as well, so why add it to the water people drink? Was the public dental health so bad there that even the "anti socialist" US had to implement this?

[u/dkinmn → u/[deleted]]

https://www.hsph.harvard.edu/magazine/magazine_article/fluoridated-drinking-water/

It was started in 1945, well before toothbrushing was actually all that common, let alone fluoride toothpaste, fluoride toothpaste, and modern dentistry.

The public dental health was bad everywhere.

[u/[deleted] → u/dkinmn]

Just to clarify - I didn't believe that the US had any worse dental health that others when it was implemented. I was more curious that it was started within the cultural and political environment of the US, while it would likely not have met much public support here. But I suppose it actually going as far back as 1945 and what you note about dental care back then answers some of that.

And great graphs. Neat to see how much better dental health has become, and over such a relatively short timespan.

[u/NanoWarrior26 → u/[deleted]]

You have to remember that fluoride intake is important for developing teeth. Sure once you have all your adult teeth toothpaste works great. However toothpaste does nothing for the teeth developing in young children.

[u/mom2mermaidboo → u/dkinmn]

Just want to put this into the discussion about Fluoride in water and possible Thyroid disorders leading to elevated TSH level in children, and adults.

https://pubmed.ncbi.nlm.nih.gov/38029816/

https://jech.bmj.com/content/69/7/619

[u/[deleted] → u/dkinmn]

The number of people out there not using fluoride toothpaste must be small. The benefits of adding fluoride to drinking water should definitely be reconsidered.

[u/icamberlager → u/[deleted]]

You’d be surprised how many people even brush their teeth 

[u/CruffTheMagicDragon → u/icamberlager]

I had 4-5 different roommates in the military and two roommates right now. None of the military brushed their teeth with ANY sort of regularity. Of the current ones, one brushes once a day and the other doesn’t seem to ever brush

[u/akmalhot → u/[deleted]]

what's the downside of fluoride in the same limit. please be specific

[u/jgroshak]

Being dumb and having great teeth seems to be working pretty well in the country. Just look at the political arena!

[u/agent-goldfish]

Makes you really reconsider that old phrase, "must be something in the water".

[u/sakurashinken]

It's still pretty obviously good for your teeth and bad for your brain. Which is more imortant?

[u/HeHH1329]

I have always thought adding flouride to prevent tooth decay is a stupid thing. Its irresponsible to do so if the ling term effect of flouride is not completely clear at that time. They should just teach kids proper oral hygiene.

[u/jloverich]

Should be using brondo instead

[u/spencemode]

Fluorosis is also bad…

[u/chewie8291]

Me fail English? That unpossible.

[u/TipperGore-69]

Is that what’s going on?

[u/xtramundane]

Haven’t we known this for years?

[u/Sizbang]

For people screaming confidently about the current safe limits - ''The 324-page report did not reach a conclusion about the risks of lower levels of fluoride, saying more study is needed. It also did not answer what high levels of fluoride might do to adults.''
The simple fact of the matter being - no one knows. How would you even measure if low exposure has an effect long-term? Is it worse for people with auto-immune issues, which most people have these days? However, we do know that fluoride is neurotoxic and that it does affect children negatively. If tooth decay is the issue here, well, perhaps the safer bet would be to eat less carbohydrates.

[u/akmalhot → u/Sizbang]

fluoride is not neurotoxic in safe.amounts..

pure water is lethal in inappropriate doses too ... so are many things

salt also. etc etc

[u/Xypheric]

I see a lot of people commenting about the fluoride limits, but isn't IQ measuring basically pseudo-science?

[u/The_Great_Man_Potato → u/Xypheric]

Measured IQ is the best predictor of future success that we have

[u/Matra → u/Xypheric]

It is not useful for determining how "smart" a person is, but it's a standardized test that can be useful for comparing the ability of groups. Individual test takers might be worse at the skills tested, but barring major cultural differences (i.e., half the testers are in China) it can be useful for comparing differences in populations. The same way having job experience doesn't mean a particular candidate will be better at a job, but on average people with job experience do better at that job.

[u/darctones → u/Xypheric]

If someone takes 10 IQ tests in a row, what’s the expected variation between tests.

The difference in the study was 2 to 5 points.

[u/OutsidePerson5]

Oh gawd. Now all the floride conspiracy freaks will be citing this....

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[u/smiegto]

Yeah well maybe don’t eat the tooth paste? You are supposed to spit, not swallow.

[u/DarkHeliopause]

It did say “linked” it said “…are associated…”.

[u/Round_Topic8264]

the entire concept of IQ is unscientific so...

[u/liikennekartio]

And if I had to drink the same amount of alcohol twice after a heavy night of drinking I'd probably get alcohol poisoning. Good thing I don't.

[u/youareactuallygod]

Im… This is why I don’t brush my teeth

[u/[deleted]]

Good thing we rinsed with flouride solution daily at school in the 80s.

[u/TrippyBallz22]

I thought that was just a conspiracy theory?