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Fluoride Exposure and Children's IQ Scores a Systematic Review and Meta-Analysis

30 points by logicchains 2y ago

deleted 2y ago
[deleted]
mensetmanusman 2y ago
Takeaways: -Higher fluoride exposure may negatively affect children’s IQ. -At lower levels, particularly in water, this effect seems weaker or non-existent. -More careful studies still show a potential risk, even at relatively low exposure levels.
- trod1234 2y ago
  Growing body of science for what some people have been saying for years now.
simple10 2y ago
TLDR; children who got higher fluoride exposure tended to have slightly lower IQ. Lower amounts in drinking water <1.5 mg/L were inconclusive on IQ impact and requires additional study.
lalaland1125 2y ago
It's very interesting that the group level results (table 1) of this analysis seem entirely opposite when comparing western and non-western countries. As noted by table 1, all the group level results indicating that fluoride has a negative impact on IQ come from China, India and Iran. When you look at the studies done in western countries, in particular Canada, New Zealand, Taiwan, Australia, Sweden, Denmark or Spain, you do not see negative IQ effects (Australia, Sweden, Denmark and Spain studies were not included in this meta analysis, but you can find links to studies from those countries in https://www.statnews.com/2025/01/06/fluoride-iq-jama-pediatrics-critiques-meta-analysis/ https://www.statnews.com/2025/01/06/fluoride-iq-jama-pediatr...).
- AlanYx 2y ago
  >As noted by this meta-analysis itself, all the results indicating that fluoride has a negative impact on IQ come from China, India and Iran. That's not accurate. Table 3 shows negative impact from data collected in Canada and Mexico as well.
  - GettyVilla 2y ago
    The Canadian and Mexican studies are invalid because they use spot urine to measure fetal fluoride exposure. Spot urine of the pregnant woman can't measure her chronic fluoride exposure. It can't tell us anything about what the fetus was exposed to. These are studies, regretfully, that might as well not have been written. They are not useful because they are invalid.
    - AlanYx 2y ago
      I think you're referring to the Canadian and Mexican studies that were excluded from the meta-analysis. If you read the paper, two Canadian studies and three Mexican studies were excluded, but not all of them were. Table 3 only shows results from studies that were judged to be robust.
- beepbopboopp 2y ago
  This feels a lot like the "blue-zone problem" in that it turned out blue zones were only prevalent in areas where they kept birth records poorly. I dont know much, but are less wealthy countries more statistically likely to create unreliable research or is that not a vector that seems to affect deep science?
  - throw194553 2y ago
    China and India are countries with highly trained good scientists, who work in a bad system. They have to make results constantly to keep officials happy. So there is a lot of research fraud. I don't know about Iran but it's probably similar. A lot depends on the field and institution but it's possible. (The West is really bad for research fraud too, but not as bad.) This meta analysis tries to look for high "risk of bias" based on methodology. But it doesn't look like they consider the possibility of fraud, only bad methodology and statistics.
deleted 2y ago
[deleted]
fridder 2y ago
The study does seem to have some problems: https://arstechnica.com/health/2025/01/controversial-fluoride-analysis-published-after-years-of-failed-reviews/ https://arstechnica.com/health/2025/01/controversial-fluorid...
Evron 2y ago
A good science based take on this issue: https://sciencebasedmedicine.org/fluoride-and-iq/ https://sciencebasedmedicine.org/fluoride-and-iq/
bitshiftfaced 2y ago
Seems like SES could be a confounder since it looks at individuals from various countries, and fluoridation policy is probably related dental health found in a population. Yet I see no attempt to control for SES.

30 points by logicchains 2y ago

deleted 2y ago

[deleted]

Takeaways: -Higher fluoride exposure may negatively affect children’s IQ. -At lower levels, particularly in water, this effect seems weaker or non-existent. -More careful studies still show a potential risk, even at relatively low exposure levels.

trod1234 2y ago
Growing body of science for what some people have been saying for years now.

simple10 2y ago

TLDR; children who got higher fluoride exposure tended to have slightly lower IQ. Lower amounts in drinking water <1.5 mg/L were inconclusive on IQ impact and requires additional study.

lalaland1125 2y ago

It's very interesting that the group level results (table 1) of this analysis seem entirely opposite when comparing western and non-western countries. As noted by table 1, all the group level results indicating that fluoride has a negative impact on IQ come from China, India and Iran. When you look at the studies done in western countries, in particular Canada, New Zealand, Taiwan, Australia, Sweden, Denmark or Spain, you do not see negative IQ effects (Australia, Sweden, Denmark and Spain studies were not included in this meta analysis, but you can find links to studies from those countries in https://www.statnews.com/2025/01/06/fluoride-iq-jama-pediatrics-critiques-meta-analysis/ https://www.statnews.com/2025/01/06/fluoride-iq-jama-pediatr...).

AlanYx 2y ago
>As noted by this meta-analysis itself, all the results indicating that fluoride has a negative impact on IQ come from China, India and Iran. That's not accurate. Table 3 shows negative impact from data collected in Canada and Mexico as well.
- GettyVilla 2y ago
  The Canadian and Mexican studies are invalid because they use spot urine to measure fetal fluoride exposure. Spot urine of the pregnant woman can't measure her chronic fluoride exposure. It can't tell us anything about what the fetus was exposed to. These are studies, regretfully, that might as well not have been written. They are not useful because they are invalid.
  - AlanYx 2y ago
    I think you're referring to the Canadian and Mexican studies that were excluded from the meta-analysis. If you read the paper, two Canadian studies and three Mexican studies were excluded, but not all of them were. Table 3 only shows results from studies that were judged to be robust.
beepbopboopp 2y ago
This feels a lot like the "blue-zone problem" in that it turned out blue zones were only prevalent in areas where they kept birth records poorly. I dont know much, but are less wealthy countries more statistically likely to create unreliable research or is that not a vector that seems to affect deep science?
- throw194553 2y ago
  China and India are countries with highly trained good scientists, who work in a bad system. They have to make results constantly to keep officials happy. So there is a lot of research fraud. I don't know about Iran but it's probably similar. A lot depends on the field and institution but it's possible. (The West is really bad for research fraud too, but not as bad.) This meta analysis tries to look for high "risk of bias" based on methodology. But it doesn't look like they consider the possibility of fraud, only bad methodology and statistics.

deleted 2y ago

[deleted]

fridder 2y ago

The study does seem to have some problems: https://arstechnica.com/health/2025/01/controversial-fluoride-analysis-published-after-years-of-failed-reviews/ https://arstechnica.com/health/2025/01/controversial-fluorid...

Evron 2y ago

A good science based take on this issue: https://sciencebasedmedicine.org/fluoride-and-iq/ https://sciencebasedmedicine.org/fluoride-and-iq/

bitshiftfaced 2y ago

Seems like SES could be a confounder since it looks at individuals from various countries, and fluoridation policy is probably related dental health found in a population. Yet I see no attempt to control for SES.