Prenatal Fluoride Exposure and Cognitive Outcomes in Children | Hacker News Reader

Prenatal Fluoride Exposure and Cognitive Outcomes in Children

ehp.niehs.nih.gov

60 pointsvixen9952 comments

Looking at the shotgun blasts they had been able to produce, I'm disappointed there wasn't a clearer signal. Take out the 130 IQ kid with little fluoride and the three kids with high fluoride and slightly-below-average IQ's and you might even be able to predict a beneficial effect to fluoride.

To clear up a few of the other questions, they didn't measure where mama was getting her fluoride, or how much was in her tap water, or even how effective she was at excreting it. They also didn't measure postnatal fluoride exposure by the children, which may be less, more, or just as important.

Mama could have swallowed some toothpaste or mouthwash even though she lived on unfluoridated water. She could have eaten a steady diet of fluoride-infused potato chips manufactured in a place with fluoridated water even though her water was unfluoridated. Or, she could have been a tea drinker, which is a leading source of fluoride.

Absent evidence to the contrary, I believe this study's conclusions are the right ones, but the study could do little to back them up. For all we know (and for all the efforts the study didn't make to rule it out), higher fluoride exposure could simply be a reflection of poverty, which would similarly correlate to lower childhood IQ's.

If you drink untreated water in Mexico, you may very well be drinking fluoridated water, which occurs naturally in some spots. El Paso and Albuquerque have naturally fluoridated water.

They adjusted the results for the excretion ratio (adjusted for urinary creatinine and specific gravity, respectively).

Note that at least in Europe the toothpastes for children contain no fluoride.

In Germany toothpaste for children contains a third of the flouride of toothpaste for adults (500ppm).

Some brands of toothpaste substitute fluoride with xylitol. There is evidence that it hardens enamel.

https://www.ncbi.nlm.nih.gov/pubmed/14700079

https://www.sciencedirect.com/science/article/pii/S091723940...

Oh, boy. This will be fun.

To the (many) people in this comments section who seem unable to read, here's the conclusion of the study:

"Community water and salt fluoridation, and fluoride toothpaste use, substantially reduces the prevalence and incidence of dental caries (sic) (Jones et al. 2005) and is acknowledged as a public health success story (Easley 1995). Our findings must be confirmed in other study populations, and additional research is needed to determine how the urine fluoride concentrations measured in our study population are related to fluoride exposures resulting from both intentional supplementation and environmental contamination. However, our findings, combined with evidence from existing animal and human studies, reinforce the need for additional research on potential adverse effects of fluoride, particularly in pregnant women and children, and to ensure that the benefits of population-level fluoride supplementation outweigh any potential risks."

This is a preliminary study that doesn't even try to establish a causal connection between water fluoridation and intelligence. It suggests an avenue of future research. It's not a license to assert whatever fringe beliefs you want. The evidence is that water fluoridation is safe and effective. Maybe future studies will change that, but those studies have yet to be done.

We should all be skeptics. Dismissing the consensus in favor of conspiracy theories is not skepticism. It is blind credulity.

They found a 2 IQ point difference testing kids 6-12 years old with a sample size of 500. I'm not sure why I'm supposed to believe anything in this study.

I understand that it's expensive to run longer studies, but with an effect size of 2 IQ points, they'd really have to test the kids post puberty at a minimum. Otherwise the numbers will just be too volatile.

500 sounds like a sufficient sample size to me. How many samples would you need before accepting the results of a study?

It's not necessarily any one aspect of the study, but all of the elements as a whole.

1. This is an observational study, not a double blind experiment. We know that these are basically garbage. In many cases it's unethical to do experiments, so observation is the best we have; that doesn't mean it's any good.

2. IQ pre puberty is highly volatile. The younger you test, the less your results correlate with eventual adult IQ.

It may be possible to add say 100x more participants to compensate for the 2nd point. You can't add more participants to fix the first point; blacklisting confounders just doesn't work except in exceptional cases (e.g. smoking and cancer).

The real way to do this study is

1. Double blind study instead of observation. This means along with everything they're already doing, they need to give the mothers a 16 year supply of water filters (presumably over time). Half of them would be inert.

2. Run the study until the kids are at least 16.

Yes, this is more expensive, but the knowledge per dollar gained would be infinitely higher.

> but the knowledge per dollar gained would be infinitely higher.

Would it be? It sounds like millions, potentially tens of millions, would be required to run this hypothetical study. And the likely outcome is that the effect is minimal.

>> but the knowledge per dollar gained would be infinitely higher.

> Would it be?

I meant that literally. 1/4x is infinitely larger than 0/x

> And the likely outcome is that the effect is minimal.

Everyone knew this was true before the study started.

I misunderstood. I thought you were saying the knowledge would be worth infinitely more than the millions this would cost.

https://www.ada.org/en/publications/ada-news/2017-archive/se...

Where does toothpaste fall on this scale?

Fluoride toothpastes sold in the U.S. generally contain between 1,100 and 1,450 parts per million (ppm) fluoride (the equivalent of over 1 mg of fluoride for each gram of paste). http://fluoridealert.org/issues/dental-products/toothpastes/

Is that enough to lower intelligence? I couldn’t seem to figure it out from the paper.

The authors of the paper wouldn't claim to know. They measured levels in urine and have no idea where that fluoride came from.

Maybe if you change your brand of toothpaste you will?

Supposedly fluoridation leads to a change in the pineal gland, which is a partially understood part of the brain. Any truth to that?

But why fluoridate? Why add fluoride to the water supply? Even IF it helps prevent tooth decay and even IF we knew there were no harmful side effects, how is that a reason? Why not add something to make hair shinier? Or your breath smell fresh? Or something for heart disease? It's such an arbitrary thing to add to water. Besides, with fluoride in toothpaste, what's the point?

I would prefer that nothing were added to tap water. Leave it alone.

The savings of public funds (e.g. avoided emergency room visits resulting from cavity) due to cavities dwarf the private savings.

Dental health is not just cosmetic; it affects multiple areas of physical health. If there were a safe way to add something that would prevent heart disease, it would absolutely be in the public interest. Your other examples are strawmen.

You can certainly argue (as this paper’s conclusion does) that more research is needed on other potential effects of fluoridation, but it isn’t arbitrary.

and fluoridation doesn't affect dental health because you're drinking the water which means the fluoride doesn't get to the teeth but is absorbed elsewhere in the body. If you want fluoride you can get it through toothpaste. It should be a choice.

So, does it turn out that all those nut jobs who ignored science and claimed that putting a neurotoxin in the water supply was a bad thing might have had a point?

More public utilities remove naturally occurring fluoride from the water so that it stays below the WHO suggested safe levels 0.5 to 1.5 mg/L.

The paper doesn't actually argue a linear relationship and seems to show .8 mg/L might be ideal, which is the lower part of the current range. But I think you would need a much larger study of people exposed to the recommended range to see if lower is always better.

No; it turned out that bad studies produce not very useful statistics.

Others in this thread have already indicated why this study doesn't help with much. Unfortunately it will just give the anti-fluoride crowd ammunition.

Why don't Europeans fluoridate?

Because they have working public health systems?

Actually, I think it's a pretty personal and difficult question to answer that's unlikely to be uniform across Europe. Perhaps it's because they drink more tea and coffee which themselves have high fluoride levels (~3-5x fluoridated water levels in the US?

http://fluoridealert.org/issues/sources/tea/

Because they ad fluoride to salt (or sometimes in milk).

In some places they remove naturally occurring fluoride from the water until it reaches what the WHO considers safe.

I've never understood this view. Do you think all the other educated people who look at this issue are thinking "haha, more doop in the water to poison everyone!"?

I personally always choose the highest fluoride toothpaste I can, because the benefits of reduced tooth issues make up for a (if you believe this paper and their pointillism graph) 1.2 pt iq drop.

It always makes me sad how many people think that just because some group is making a decision that affects them, that group is out to get them.

And, before someone says it, no, I'm not opposed to these studies being done occasionally for the sake of conventional wisdom being wrong, but people shouldn't try to make hay off a non-effect.

I think people are upset (perhaps now rigthly) that fluoride was added to public water supplies and most toothpaste. It's one thing for you to be able to seek out toothpaste. It's another for it to be pushed on everybody.

Isn't that the cost of using a public good? I might not like that the municipality cleans waste out of the water (not having it could lead to allergies, right?) or traffic lights (because what if I have to get somewhere fast in an emergency?), but that's the price I pay for living on the grid.

Finally seeing the Squidbillies episode from 2010 in real life

Was the anti-fluoride movement ever not based on scientific studies?

I remember reading that arguments for fluoridation are rather weak and that fluorosis of the bones is common.

Conventional wisdom is often wrong.

Are teeth more important than brain? Only when your real interest is to sell more sugary drinks and processed sugary foods. Sugar is cheap and addictive and if you somehow fix the tooth decay, it is your "perfect product".

Serious questions need to be asked about the World Health Organisation for supporting and pushing fluoridation globally.

This is a conspiracy theory view which isn’t worth giving much consideration to.

Since a couple of years, I use the Himalaya Herbals Indian toothpaste, with fluoride from natural sources only, and I heavily endorse it.

The title I supplied was " More research on potential adverse effects of fluoride is needed" and was taken from the paper. Not sure how the actual paper title appeared.

This makes me wonder if fluoride could be a cause of the rise in autism.

Where are those fluoride shills, proclaiming the great benefits of involuntrary medicating everyone to improve teeth by osmosis(fluoride is applied topically)? Sooner or later, this will be on the same page of history as asbestos and leaded fuel.

I mean there is pretty compelling evidence that water fluoridation reduces tooth decay in children. I’m not clear what your objection is - are you suggesting this is not the case?

http://fluoridealert.org/new-visitors/teeth/

Yeah, I think the chances of "fluoridealert.com" being a legitimate source of scientific information to be pretty slim.

Do kids really need fluoride before their adult teeth start to grow in?

They don't "need" it, but my understanding is that water fluoridation reduces rates of tooth decay in both deciduous and permanent teeth.

Not really. Tooth paste for kids generally doesn’t contain fluoride to begin with. But it’s still important to get kids into the habit of brushing and prevent gum disease.

My understanding was that there is compelling evidence for topical application (e.g. how the dentist applies it as well as toothpaste) but not much evidence for water supply.

Do you have a link to the research you mention?

That's exactly the point: topical application vs. systemic ingestion. I've yet to see a credible model for ingestion having any uniformly beneficial effect.

Toothpastes, rinses, and topical application by professionals are fine. Otherwise, I'll pass.

Let's put it this way:

There is pretty compelling evidence that leaded gasoline reduces knocking in car engines, and that asbestos reduces fire deaths in buildings.

No one's debating the direct goal of fluoride- it's the externalities that make the matter controversial.

Also the fact that there's already fluoride in food, perhaps more than we get from swallowing toothpaste (and which is after all topically available to the teeth!) Also that food could be fortified with Vitamin D3 which might also reduce tooth decay, perhaps more effectively.

On the societal scale, a slight decrease in the average IQ due to fluoridation might correspond to a larger deficit at the genius end of the spectrum. Society disproportionately benefits from the work of geniuses & it should protect them more.

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