Comment by tashar
21 days ago
> Thoroughly scientifically debunked. Repeatedly, over decades.
"The NTP monograph concluded, with moderate confidence, that higher levels of fluoride exposure, such as drinking water containing more than 1.5 milligrams of fluoride per liter, are associated with lower IQ in children"
This is from an NIH meta-analysis. Its a pretty rigorous study.
https://ntp.niehs.nih.gov/whatwestudy/assessments/noncancer/...
"It is important to note that there were insufficient data to determine if the low fluoride level of 0.7 mg/L currently recommended for U.S. community water supplies has a negative effect on children’s IQ"
This is why there's such a fierce debate. Based on the most recent scientific literature there seems to be evidence of a dose-dependent effect of fluorine levels in water and lowered IQ in children, meaning it has some kind of neurotoxic effect. But we don't have robust evidence to say 0.7 mg/L has a similar effect. That doesn't mean it is DEFINITELY safe, it just means more research needs to be done and the current research that does cover the 0.7 mg/L range may not reach statistical significance.
The fact though the NIH suggests 1.5mg/L is likely unsafe, which is only 2x what America's tap water contains, I would not blame people for being uneasy about. It is often the case the that the FDA regulates food additives that have potential negative side effects to be limited to concentrations 10x lower than what is seen as unsafe.
I am not suggesting it's a straightforward choice to defluorinate water, but I see people often repeating claims like you have that dangers of fluoride are "thoroughly debunked" and that's simply not true. I don't blame people for having that sentiment either, because 0.7mg/L is seemingly still considered safe, and some of the loudest advocates of defluorination have no shortage of thoroughly debunked crazy views on things (possibly due to brains half eaten by worms). It makes it very easy to brush off the skepticism.
But it's also important to keep in mind science is built on the premise that one must be ready to re-evaluate past assumptions when new data arises, and generally speaking the new data around fluoride I hate to say seems to show there is indeed smoke.
It's also the case that when the US initially fluorinated water supplies it was a massive public health success, but these days it seems to make a much lower impact now that fluoride toothpaste use is ubiquitous (plus the levels were lowered from 1.0mg/L in the 70s, likely reducing its overall effectiveness). It is IMO both very reasonable to fund more research into this to know conclusively if 0.7mg/L is indeed safe, and also consider public health policy that focuses on promoting dental hygiene through other means in places that do defluorinate.
I do not agree with Utah's decision here mostly because it seems to neglect that defluorination will create a void that requires other public health policy efforts to fill it, poorer and less educated communities will suffer unless government led efforts to promote and make dental hygine affordable are not also undertaken.
> It is IMO both very reasonable to fund more research into this to know conclusively if 0.7mg/L is indeed safe
How exactly do you propose we do this? It's tough to prove absence of harm.
The meta-analysis put together tons of research under different situations, and found a weak and relatively small dose-response relationship above 1.0 mg/L and failed to find a relationship below. The evidence between 1.0mg/L and 1.5mg/L is particularly weak. And, of course, most dose-response curves are sigmoidal, so the failure to find a response under 1.0 mg/L is most easily explained by the inflection point being above that level.
If you're not satisfied when combining 74 studies fails to find a relationship, will you be happy with 75? 76? 100?
(Sure, a big proportion of the studies and study power focused on higher levels of fluorination-- and I always support filling gaps in research; but it's not like we have an absence of research below 1.5 mg/L).
Well I mean the flip side is... does community water fluorination at its current levels actually help?
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD...
The Cochrane Collaboration's research is near the gold standard, and yet they find surprisingly limited evidence of benefit for CWF in the modern research:
"These low‐certainty findings (a 4 percentage point difference and 3 percentage point difference for primary and permanent dentition, respectively) favoured CWF."
3-4% reduction in cavities is not nothing, but it's a far cry from the 60% drop observed in the 1940s and certainly much less than what I think most strong proponents of water fluoridation would have you believe. The ongoing discussion I find quite legitimate given we're no longer living in the 1940s and CWF seems to have a substantially lower benefit than it once did, and likewise we do notice a concerning trend with fluorine neurotoxicity that has only emerged in the last few decades of research.
Public health policy is all about a risk/benefit analysis, and CWF is one of those topics that I feel legitimately should be discussed because much has changed over the many decades since the US first introduced it and since then the risks seemingly have gone up and the benefit has astronomically gone down.
Again, I do not think there'd be much discussion if current water fluorination was at 0.15mg/L, and we started seeing a negative trend at 1.5mg/L. But I don't think its actually at all unreasonable for public health officials to be worried and possibly start considering alternatives to CWF out of an abundance of caution.
3-4% of your teeth is an entire tooth.
> but it's not like we have an absence of research below 1.5 mg/L).
But it is?
>> "It is important to note that there were insufficient data to determine if the low fluoride level of 0.7 mg/L currently recommended for U.S. community water supplies has a negative effect on children’s IQ"
Yes you would need a higher powered study to rule out the potentially smaller effect, but when your treatment can affect tens of millions of children, it doesn't seem crazy to ask for more funding.
> > but it's not like we have an absence of research below 1.5 mg/L).
> But it is?
But it isn't. There's 7 studies included in that meta-analysis looking at levels below 1.5mg/L, covering 2832 children. The effect measured so far across all of the studies is a statistically insignificant increase in IQ.
I'm in favor of additional research; I just don't think getting to n=10,000 showing little or no effect is going to convince anyone. I also don't think that these possible modest effects are going to be in the top 5 most important environmental stressors to measure the effects of.
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