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Study suggests link between fluoride and IQ — but don't panic just yet

arthwollipot

Observer of Phenomena, Pronouns: he/him
arthwollipot
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Study of fluoride during pregnancy and children's IQ raises questions but draws criticism

A new study links fluoride consumption during pregnancy to lower IQ in children, but experts are saying it's not time to rush out and filter your H2O just yet.

Researchers in Canada found women who drank fluoridated tap water while pregnant had children with slightly lower IQ scores than women who lived in non-fluoridated cities.

The message from public health experts, however, is "don't panic".

While the authors of the study claim the research "raises possible concern", other researchers say the findings don't move the needle much — if at all — on the question of fluoride safety.

"The overwhelming body of evidence is still supporting water fluoridation," said Matt Hopcraft, associate professor of dental public health at the University of Melbourne.

"Here's a single study that points a little in the other direction. I think we just need to be cautious."
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Here's the study, for those who are more qualified than I am to read scientific studies. But without good reason I'm not changing my opinion of water fluoridation.
 
So the toddlers of people who (can afford to!) buy bottled water have slightly higher IQs?
 
dann said:
So the toddlers of people who (can afford to!) buy bottled water have slightly higher IQs?
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The article doesn't mention bottled water - it's comparing people who live in cities with fluoridated tap water with people who live in cities with unfluoridated tap water.
 
arthwollipot said:
The article doesn't mention bottled water - it's comparing people who live in cities with fluoridated tap water with people who live in cities with unfluoridated tap water.
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It does more than that: "the researchers analysed the average fluoride concentration in the mothers' urine during pregnancy,"

That's not what comes out of the tap, I hope!
 
dann said:
It does more than that: "the researchers analysed the average fluoride concentration in the mothers' urine during pregnancy,"

That's not what comes out of the tap, I hope!
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Obviously not, but without having actually read the paper I idly wonder if they did control for the mothers (or the children) drinking bottled water.
 
Kinda, but not really:

Second, the fluoride intake data did not measure actual fluoride concentration in tap water in the participants' homes. Rather, it was an estimate of fluoride intake based on self-reported beverage consumption, and did not include fluoride from other sources, such as dental products and food.
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There is no evidence in this paper whatsoever that fluoridation affects children's IQ. The authors found a marginally significant (p=.025) relation between maternal urinary flooride and the IQ of boys, but not girls. The authors make no attempt to explain why, if fluoride exposure lowers childrens' IQs, it would only affect boys.

Just because a p-value is signficant by some arbitrary standandard, ie < .05, does not mean the result is evidence against the null hypothesis. To estimate the evidential value of the results, I computed Bayes factors*, which measure the relative support of the evidence for the null hypothesis vs the alternative, for boys and girls. For boys, the Bayes factor was 1.0, suggesting that the evidence, despite being "statistically significant," favors neither the null or the alternative hypothesis. For girls, the Bayes factor was 8.6, meaning that the evidence favors the null hypothesis over the althernative by nearly a factor or 9.

The authors conclusions are wrong. Not only did they fail to find evidence that fluoridation affects childrens' IQ, they found the opposite: that it doesn't.

______________________
* Using the BayesFactor package in R.
 
theprestige said:
Huh. I thought this was gonna be one of those joke headlines where the study showed that fluoride increased IQ.

Turns out there's actually cause for concern.
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Not really. As has been pointed out, there are a lot of problems with the study and it lacks prior plausibility, as the vast majority of studies on fluoride safety say that it is safe. Again,

"The overwhelming body of evidence is still supporting water fluoridation," said Matt Hopcraft, associate professor of dental public health at the University of Melbourne.

"Here's a single study that points a little in the other direction. I think we just need to be cautious."
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It's worth reading the whole article - I posted, like I always do when I post such things because to do otherwise is against the forum rules, just an extract.
 
Oh noes, I could have had even more potential to waste.


ETA - Just a lame joke, I'm aware of the problems with the study.
 
If I recall correctly from the NPR report, they were only talking about a one or two point drop in IQ. Would that even be distinguishable in any real world situation? I'd rather have fewer cavities if those are my options.
 
Ryan O'Dine said:
If I recall correctly from the NPR report, they were only talking about a one or two point drop in IQ. Would that even be distinguishable in any real world situation? I'd rather have fewer cavities if those are my options.
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I haven't read the study, but if there's an average drop of 1-2 points, one might assume that the effect is not consistent.

For instance if you measured the average life expectancy reduction for smoking you would be averaging people who died of cancer and people who got lucky. Whatever the average life expectancy reduction is for smoking, there's a significant risk of a much greater effect.

So if fluoride truly creates an average decreased IQ a couple points lower that would quite possibly be averaging people who experienced the effect with people who escaped it (who knows what the mechanism might be). So there might be a certain risk of a more significant drop.
 
Cavemonster said:
I haven't read the study, but if there's an average drop of 1-2 points, one might assume that the effect is not consistent.

For instance if you measured the average life expectancy reduction for smoking you would be averaging people who died of cancer and people who got lucky. Whatever the average life expectancy reduction is for smoking, there's a significant risk of a much greater effect.

So if fluoride truly creates an average decreased IQ a couple points lower that would quite possibly be averaging people who experienced the effect with people who escaped it (who knows what the mechanism might be). So there might be a certain risk of a more significant drop.
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A much more sensible way of looking at it, thank you.
 
Cavemonster said:
So if fluoride truly creates an average decreased IQ a couple points lower that would quite possibly be averaging people who experienced the effect with people who escaped it (who knows what the mechanism might be). So there might be a certain risk of a more significant drop.
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There is no evidence in the results of any effect on IQ. On the contrary, the results support the null hypothesis, that there is no effect on IQ. The authors of the study misinterpreted their own results. See my previous post.
 
Didn't take long for Pete to jump all over it.

Expert warn over controversial new anti-fluoride study

Damn, what a terrible headline that is. Anyway...

He’s said sunscreen is toxic and promoted a dangerous baby broth, now celebrity chef Pete Evans is at it again with his strangest claim yet.

Pete Evans has once again been told to stick to celebrity cheffing and stay out of scientific debate after he came out in support of a new controversial study.

Research out today in US medical journal JAMA Pediatrics found pregnant women who drank fluoridated water had babies with a lower IQ.

Not one to shy away from a controversial stance, Evans told the Herald Sun: “This has been known for ages, and this is just the tip of that iceberg.

“Fluoride is a known neurotoxin and it should not be put in our water supply.

“If people choose to add fluoride then it should be their choice to do so. I cannot wait for it to be eliminated from being added to Australian water supplies.”

Experts were quick to rubbish Evans’ comments and the researchers’ claims that pregnant women should avoid fluoridated water, or that it should be removed from our supply entirely.

Associate Professor Matt Hopcraft, the chief executive of the Australian Dental Association Victorian Branch, said Evans should stick to what he knew.

“I think we should take public health advice from the experts and he should probably stick to the celebrity cheffing and leave public health policy to the experts,” he told news.com.au.

“Of course Pete is going to jump on board and say this is the silver bullet — as a lot of anti-fluoridationists will — but overwhelmingly there’s no evidence to link water fluoridation with health concerns.”
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In other words, shut the **** up, Pete. You don't have a clue what you're talking about.
 
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