Fluoridated water is supplied to around two-thirds of U.S. residents, just over a third of Canadian residents and three percent in Europe Photo: AFP/File
health

Controversial study links fluoride in water to lower IQ

15 Comments
By Fred TANNEAU

A study published this week links exposure to fluoridated tap water during pregnancy to lower IQ scores in infants, but several outside experts expressed concern over its methodology and questioned its findings.

Fluoride has been added to community water supplies in industrial countries to prevent tooth decay since the 1950s.

Very high levels of the mineral have been found to be toxic to the brain, though the concentrations seen in fluoridated tap water are generally deemed safe.

"We realized that there were major questions about the safety of fluoride, especially for pregnant women and young children," Christine Till at Canada's York University, senior author of the paper published in JAMA Pediatrics, told AFP.

"We know that decisions need to be based on evidence, and we had no evidence on whether fluoride in pregnancy was safe, and regardless of the outcome, that knowledge was really critical."

The study looked at 601 mother-child pairs across six Canadian cities, with 41 percent living in communities supplied with fluoridated municipal water.

The researchers said fluoridated water is supplied to around two-thirds of U.S. residents, just over a third of Canadian residents and three percent in Europe.

After controlling for other toxins in their analysis, they found an increase in concentration of fluoride in pregnant mother's urine of one milligram a liter was associated with a 4.5-point lower IQ score in boys -- but not girls -- at age three or four.

When estimating the daily maternal fluoride intake instead of fluoride in urine, they found a one milligram increase in intake was associated with a deficit of 3.7 IQ points for both boys and girls.

Anticipating controversy, JAMA Pediatrics took the unusual step of issuing an Editor's Note that said the decision to publish the article was "not easy."

"Given the nature of the findings and their potential implications, we subjected it to additional scrutiny for its methods and the presentation of its findings."

But experts in fields ranging from statistics to toxicology to neuroscience expressed serious reservations.

"The key words in the paper are 'higher levels.'" said Oliver Jones, Associate Professor of Analytical Chemistry, RMIT University.

"The authors state that an increase of one milligram per liter (1 mg/L) increase in fluoride was associated with a 4.49 point lower IQ score but fluoride intake appears to have been below 1 mg/L for most people in the study, even for those with fluoridated water."

Stuart Ritchie, a psychologist at King's College London, added that it was "inconsistent" that the first analysis only found a significant result for boys not girls while the second analysis found an overall effect with no sex differences.

"I think the findings here are pretty weak and borderline," he said. "They might be interesting as part of a larger set of studies on this question, but alone they shouldn't move the needle much at all on the question of the safety of fluoride."

© 2019 AFP

©2019 GPlusMedia Inc.

15 Comments
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This has been known for decades. Japan luckily doesn't fluoridate its water unlike my country of origin England.

-2 ( +6 / -8 )

Another propaganda made by the anti-fluoride campaigners. Non fluoridated is a major reason why Japanese have bad teeth.

1 ( +8 / -7 )

It is interesting but too hyped for the results obtained, unfortunately that is to be expected because of the people that are married to the idea that fluoride has to be bad and will latch to this study as if it were a holy text.

As mentioned in the article the effects observed are weak and inconsistent. Not so weak as to be considered background noise, but perfectly on the levels of a study that can be later contradicted by others in the future without surprise.

2 ( +5 / -3 )

Poor methodology gives flawed conclusions. This is the most significant part of this article;

Stuart Ritchie, a psychologist at King's College London, added that it was "inconsistent" that the first analysis only found a significant result for boys not girls while the second analysis found an overall effect with no sex differences.

"I think the findings here are pretty weak and borderline," he said. "They might be interesting as part of a larger set of studies on this question, but alone they shouldn't move the needle much at all on the question of the safety of fluoride."

5 ( +6 / -1 )

Here is the article: https://jamanetwork.com/journals/jamapediatrics/fullarticle/2748634

They state that women living in areas with fluoridated water had an average of 0.69 mg/L of fluoride in their urine, whereas those in non-fluoridated areas had 0.40 mg/L. Thus, the effect on IQ, if any, would be about 1 point. Given the sample sizes it's difficult to draw any firm conclusions.

They also note that black and green tea are also significant sources of fluoride, which I didn't know. One more thing to worry about if you are pregnant.

5 ( +5 / -0 )

Congratulations! Did you really just figure this out!? The Nazis knew this when they were the first ones to experiment with water fluoridation on the Jews. Lower bone density and IQs were observed. This is SUPER old news.

2 ( +6 / -4 )

Naturally occurring fluoride in water is not the same as artificially induced supplies.

Cheers to you JT! You can now almost see the curve!

-2 ( +1 / -3 )

At least the dimwits will have nice teeth!

4 ( +4 / -0 )

This study is being accepted by (and even shocking) some of those that called those being against fluoridation "consipiracy theorists" or worse. The study has been peer reviewed and even scoured over by some to try to find fault and they concluded the evidence is even stronger (i.e. the negative impact of fluoridation).

The production of fluoride used for additives to drinking water is a rather disgusting process and the mechanism in which it is added does not necessarily ensure the lowest levels deemed necessary are consistently added to the water supply.

Some people see this as a deliberate attempt to dumb down the population and others see it as a way for business to make money (production and sales). Either way this is a convincing study which provides empirical data which is very hard to refute. The only controversy is it provides results that some do not like.

-1 ( +2 / -3 )

This has been known for decades.

Well no. There has been hostility to fluoridation (bordering on obsession for some people) for decades.

That ain't knowledge.

2 ( +2 / -0 )

Fluoride has been added to community water supplies in industrial countries to prevent tooth decay since the 1950s.

Not a very helpful statement. How many industrial countries? From what I can see, very few countries add fluoride to the water. Where I am (Scotland), it's illegal to do so. On the other hand, in Ireland (Republic), it is compulsory.

 Japan luckily doesn't fluoridate its water unlike my country of origin England.

Only a small number of water authorities in England add fluoride. It affects about 5 million people.

0 ( +1 / -1 )

First,

"I think the findings here are pretty weak and borderline,"

2nd, if I lost 1-5 IQ points in exchange for cavity free teeth (which I have) the last many decades, then it is well worth it.

But these studies don't appear to be worth the paper they were printed on. Knowing the facts is good, but only if they are scientifically accepted and other peer researchers can reproduce them.

1 ( +1 / -0 )

if I lost 1-5 IQ points in exchange for cavity free teeth (which I have) the last many decades, then it is well worth it.

But if you lost the IQ points so that your mother could have cavity free teeth, would it be worth it?

(Although other data appears to show that rates of dental cavities have fallen equally across places with and without fluoridated water. Presumably because things such as fluoridated toothpaste are just as effective.)

-2 ( +0 / -2 )

 The study has been peer reviewed and even scoured over by some to try to find fault and they concluded the evidence is even stronger (i.e. the negative impact of fluoridation).

Who are these "some"? because the opposite is quite common, their results are hugely adjusted for some parameters that have not been proved relevant and ignored others very well known variables that are likely to affect the data very strongly (such as lead exposure that strangely was not examined). The prior evidence was not taken in account for the statistical significance calculation, etc. etc.

Either way this is a convincing study which provides empirical data which is very hard to refute. The only controversy is it provides results that some do not like.

Not really, results are barely significant after very arbitrary adjustments, they are not dose dependent as should be expected and inexplicably affect only boys and not girls without any reason for this, as it would be expected if this was for example an amplification of background noise. Very important is also to notice that the whole significance depends on only 2 cases of boys with extremely severe learning problems that in strict studies can be classified as outliers. A good statistician normally makes a calculation to show that significance is maintained even if you don't count these 2 cases, but for some reason in this article it was not done.

There is no need for controversy for the paper, science works like this. The results are interesting but at the level of prior evidence and the valid criticism this can very easily be one more example of a study that do things properly and still get wrong results. Thinking a single study with very limited significance in its results is enough to prove something is simply a mistake.

1 ( +1 / -0 )

Japan luckily doesn't fluoridate its water unlike my country of origin England.

The leading opponents/lobbyists against fluoridation of water in Japan are dentists.

The reason is it would lead to a reduction in cavities and therefore less patients.

All hail the lobbyists.

gary

2 ( +2 / -0 )

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