Anti-Fluoridation is Science Illiteracy

culture, health, politics, Science Denialism, skepticism 10 Replies

A few days ago, as part of a twitter conversation I was having with the basically anonymous @SafeWaterHfx, I was sent an article in support of their claims that fluoride shouldn’t be added to municipal tap water. The anti-fluoridation crowd make a lot of noise online (they’re not unlike the anti-wifi folk in that regard), but there doesn’t seem to be any evidence in support of their position. Moreover, all the evidence seems to say that adding fluoride to municipal drinking water is a win in every possible way: it has a large positive effect on the population, it’s cheap, and it’s effective.

The argument that SafeWaterHalifax is putting forward (and you have to read between the lines as they’re either unwilling or unable to make an explicit direct statement) is that the levels of fluoridation in the municipal water in the US and Canada is harmful. Sure, they might prefer to couch that as “could be harmful”, but that’s just hedging. Given that they are arguing for it to be removed, you can’t make that argument on the basis that something “could be” harmful, without some sort of belief that it actually is.

First the tweets that led up to this:

Notice that the article linked here isn’t actually the article that was supposedly found in The Lancet (although that was named a couple of days later: Grandjean P, Landrigan P. (2006). Developmental neurotoxicity of industrial chemicals. The Lancet 368: 2167-2178). This is a constant issue when trying to deal with the anti-stuff brigade: trying to get them to actually be clear about their points and where they’re getting their information from is like trying to nail smoke to the wall.

I really wish I was the first to write about this, but a buddy of mine (who apparently knows everything that has happened in the world of Skeptics, ever) was quick to point me to places this has been debunked already. I’d like to go into a little more depth than those places though.

To begin with, it’s important to note that this is a meta-analysis. This means that this paper does no new research itself, but it is collecting and amalgamating a bunch of different studies that were done, perhaps to see if there was a common effect that would otherwise be missed. The Achilles heel of a meta-study is that it can only be as good as the studies that go into it.

The studies that went into this were all conducted in China. The Neurologica post makes the point that:

First it should be noted that almost all of the studies reviewed were conducted in China (one was conducted in Iran) – not in the US. China had a limited fluoridation program for a time, and has had no fluoridation of drinking water since 2002. So why, then, are most of the studies from China?

I dislike this paragraph, and I think it has no real place in a review of the meta-analysis. The authors of the study note that their goal was to bring Chinese-language studies to the attention of those in the English-speaking world. This seems, to me, to be a laudable goal, thus criticising this strikes me as unreasonable. There are waaaaay more problems here that could be addressed, rather than merely Poisoning The Well.

The studies that went into this meta-analysis were all observational studies. This means that rather than directing the people in a particular area to ingest more or less water, they simply located populations that they were pretty sure had a low consumption of fluoride and a comparable population they were pretty sure had a high consumption of fluoride, and then ran IQ tests on both populations. Given the ethics of administering high levels of fluoride (a known neurotoxin), the only possible study that could be done here is observational. I think that the way these studies were set up was quite ingenious.

However. The shine rapidly goes off the rose. Of the studies reviewed, the sole source of fluoride was drinking water in only 9. Most of the others involved fluoride from coal-burning, or also included arsenic exposure, and other heavy metals. This means that, with regards to the relevancy of this meta-analysis, only those 9 studies are relevant to the situation in the US and Canada. If you scan through the exposure levels, many are simply “high” and “low”, without any documentation of what that actually means (this is something that was not collected in the initial observational study). More explicitly, the reviewers say:

Our review cannot be used to derive an exposure limit, because the actual exposures of the individual children are not known. Misclassification of children in both high- and low-exposure groups may have occurred if the children were drinking water from other sources (e.g., at school or in the field).

The setup was that there are people who are all living in the same area, but some live closer to a water source that has higher levels of fluoride than the other water sources in that area, so the people were grouped (it appears) according to whichever source they used. However, they can’t rule out kids going to their friends’ houses and getting water there, or someone bringing them water from another source, or any other useful piece of information which would help make a more solid argument.

Home life is known to have a profound effect on learning outcomes and intelligence in kids. The socioeconomic household of the parents absolutely cannot be ignored, as it will explain some differences in IQ scores in different populations. And yet:

Information on the child’s sex and parental education were not reported in > 80% of the studies, and only 7% of the studies reported household income.

There may well be a correlation between people in higher socioeconomic brackets and living in the low-fluoride-exposure areas. We have no way to rule out (i.e. control for) that possibility, because that (highly relevant) information was not collected.

Again, focusing on relevancy:

The exposed groups had access to drinking water with fluoride concentrations up to 11.5 mg/L (Wang SX et al. 2007); thus, in many cases concentrations were above the levels recommended (0.7–1.2 mg/L; DHHS) or allowed in public drinking water (4.0 mg/L; U.S. EPA) in the United States (U.S. EPA 2011).

So the groups with “high” exposure were, in many cases, consuming above the allowed US levels of fluoride (nevermind the recommended), which means that the “low” exposure groups are more akin to the current situation in the US. In short, this whole review has little to no relevance to the US or Canada, unless someone here was arguing for *increasing* the amount of fluoride in the water.

But for the sake of argument, let’s toss out all of these concerns. Let’s pretend that we had full socioeconomic backgrounds on all the families. Let’s pretend we had the precise exposure rates of every single child involved in these studies, and that we define “high” exposure as 0.7–1.2 mg/L, and “low” exposure as 0.1-0.2 mg/L (i.e. so the levels in the US and Canada fall into the “high” category). Let’s, in short, pretend that this study was near flawless and could not be rejected on the basis of methodology. What was the result of the meta-analysis? Buried (practically hidden) in one of the tables, the kids with the “high” exposure had an IQ that was, on average, 0.29 points lower than the kids with the low exposure (“–0.29 (–0.44, –0.14)”).

Yes, you’re reading that correctly: 0.29. If the average for the kids with the low exposure was 100, the average for the kids with the high exposure was 99.71.

The margin of error on most IQ tests is around 3 full points. The apparent “loss” that these kids were experiencing is 10% of the margin of error of a regular IQ test. Normally, if I score 98 on the test, and you score 102, given that our ‘real’ IQ is considered to be within +/-3 of the score we received on the test, then you and I (with a difference of 4 full points) are considered to have roughly the same IQ. A difference of 0.29 is, for all practical purposes, nothing.

Now I’m not saying that throwing out this study means that fluoride is entirely safe, and we should just start adding it to our lunch menu. But this study does not support the claims the anti-fluoride fear-mongers are making. At all.

Surprise, surprise.

Follow Brian on Twitter!

10 thoughts on “Anti-Fluoridation is Science Illiteracy

  1. Steven Novella

    Brian, You are misrepresenting my post. I bring up the point about the studies being in China, which does not have a fluoridation program, not to poison the well, as you suggest, but to raise the issue of relevance – which is the exact issue you also raise. Perhaps you should have quoted the next paragraph, in which I write:

    “So the question is – how do these levels of exposure relate to the amount of fluoride being added to water in the US (because toxicity is always all about dose)? There was a lot of variability across the studies, but generally the high fluoride groups were in the 2-10 mg/L range, while the reference low fluoride groups were in the 0.5-1.0 mg/L range (not including the coal burning studies, which had much higher fluoride levels).”

    So – they looked at studies in countries with very high industrial fluoride exposure, rather than countries with fluoridation programs.

  2. Anonymous

    Neurologica wasn’t poisoning the well. Their point was that China isn’t a good place to study the effects of water fluoridation… since it “had a limited fluoridation program for a time, and has had no fluoridation of drinking water since 2002″. That’s a perfectly reasonable argument, and not a logical fallacy.

    That the goal of the authors of the meta-analysis was noble/lofty (i.e. “to bring Chinese-language studies to the attention of those in the English-speaking world”) doesn’t excuse using studies from a population that is inadequate for answering the question at hand.

  3. Brian Lynchehaun Post author

    I apologize. I misunderstood thee context of your comment. I’ll strike out that particular line of the post when I get home.

    Looking at this at a bigger screen now: it’s still not clear to me what the relevancy of China is. Either the doses are comparable, or they’re not. While the paragraph you quoted does question relevancy, the paragraph I quoted doesn’t have any obvious link with the second. It appeared (and appears) to me to be merely a rhetorical dig at the source of the study.

    The point of the study is to compare the effects of fluoridation on IQ: what does it matter if the country has a fluoridation program, or not?

  4. Steven Novella

    Brian – your last sentence makes no sense. How can you study the effects of fluoridation in a country without fluoridation? These are studies of industrial-level toxic exposure of fluoride (and likely other contaminants), but they were presented as evidence of the dangers of fluoridation. The relevance of pointing this out should be obvious.

  5. Brian Lynchehaun Post author

    Fine: the point of the study is to compare the effects of different doses of fluoride on IQ: what does it matter if the country has a fluoridation program, or not?

    This kind of hair-splitting seems puerile.

  6. Mattrick Holbert (@Mattrickph)

    It would seem to me that if there were evidence, which indicated to the observers of the study, that an amount of this substance has a detrimental effect on a human or animal, it should be removed from the water table immediately. According to the wikipedia for hexaflourosilicic acid, “The LD50 value of hexafluorosilicic acid is 70 mg/kg.” And according to a Canadian website, hydroflourosilicic acid is coming from, well you can see here: http://cof-cof.ca/hydrofluorosilicic-acid-origins/

    Should we not be considering where this chemical is coming from in the first place, and instead of turning a blind eye to the injustice of this industry to the environment, as well as to our own health? When will the compartmentalized perspective meet its end? Even if this may cause a fraction of a percent of any population to experience an effect of lowering the IQ or neural efficacy, it must be removed from our water table immediately!

    And as for the environment, I mean my god; I am a scientific pantheist and this is just awful. I realize that these chemicals have practical applications for making widgets that make your life more convenient and awesome, but do those widgets make you so happy its worth killing the air for animals and people alike?

    Lets grow up and realize we have a higher calling than that. We live in times of change, where the forms to which we are accustomed will no longer grant us the freedom we deserve. We must acquiesce to a balance of industry with our ancestral heritage and persuasion. If we become too distant too quickly, we will destroy ourselves like a child with a loaded gun.

  7. Brian Lynchehaun Post author

    The actual amount of flouride in the water is nowehere near the LD50 amounts.

    I invite you to provide evidence that it is. (or else go away with your nonsense)

  8. Mattrick Holbert (@Mattrickph)

    Well, one thing that we must recognize is that we are talking about a (semi) lethal dose when we reference the LD50 system. One does not need to have a lethal dose for something like a neurotoxin to have a detrimental effect on a persons brain chemistry or neuronal structure over time.

    Rather than demanding we fluoridate our water–for the children and childlike individuals–to prevent tooth decay, why don’t we wake up and see that we are A) giving our children way too much sugar, and B) that we are putting a carcinogenic chemical into our water to prevent tooth decay, when this stuff can cause fluorosis that damages their teeth anyway.

    Now, even if this chemical were shown not to have the negative effects on the brain and on the environment that it obviously does, what is the point of putting it in the water everywhere? I can see putting it in rural places that have a more prevalent issue with tooth decay, or in inner cities that have a diet of primarily sugar and contrived food-like products, but to administer it everywhere is a mass medication of the population without consent.

    I have searched the CDC’s database for information regarding flouride amounts administered in my area, but there was no data. Then I checked my local consumer confidence reports (in two areas around where I live), which showed that both had different levels. My area has a level of .44-.64 ppm, which is considerably higher than a more rural area with .13-.21 ppm. However, that being a significantly lower level than the standard LD50 does not mean that I am glad that it is in the water. Further, it does not explicitely state whether or not this level is before or after treatment–as in whether this is just the natural amount of fluoride prior to treatment, or post treatment levels, and I am waiting on a call from my local water treatment facility to give me that information. Further, there is no real conclusive way to know how much one is ingesting either through drinking or through brushing, therefore this kind of information is relative and not adequate for discerning real life amounts ingested by individuals.

    Furthermore, if you look into how this chemical is produced, and the difficulty of disposing of it due to its toxicity, it is obvious and well reasoned to recognize why it is put into our drinking water: money. The cost of disposing of fluoride vs the cost of putting it into the drinking water is a no brainer for a government that wants to make money over making sense. And by selling the idea that the costs are outweighed by the rewards, you and many others are duped into believing that this kind of treatment is for your best interest, and the best interest of your children–which you may or may not have.

  9. Brian Lynchehaun Post author

    Well, one thing that we must recognize is that we are talking about a (semi) lethal dose when we reference the LD50 system. One does not need to have a lethal dose for something like a neurotoxin to have a detrimental effect on a persons brain chemistry or neuronal structure over time.

    We seem to be in agreement that your bringing up the LD50 was entirely irrelevant.

    even if this chemical were shown not to have the negative effects on the brain and on the environment that it obviously does

    Nope. Let’s stop the bullshit train right there: there is zero evidence the flouride has any negative effects on the brain and/or environment at the current level found in water.

    Please don’t just make shit up.

    to administer it everywhere is a mass medication of the population without consent.

    /eyeroll

    The cost of disposing of fluoride vs the cost of putting it into the drinking water is a no brainer for a government that wants to make money over making sense.

    This is up there with chemtrails, and 9/11 denialism.

    Look, if you ever have an argument is that things are “obvious” and “a no brainer”, then you have a shitty argument. If it were “obvious”, then there would be no dispute. The fact that you have leapt to this unsupportable conclusions does not make them “obvious”.

    Even if your bullshit conclusions were true, you would still have to explain the reasoning behind getting them. “It’s just obvious” means “I have no idea how I came to this conclusion”.

    You are welcome to continue this discussion, but failing to address the above (i.e. needing evidence to show that flouride causes harm at the current levels in water, and evidence in favour of your conspiracy nonsense) means that your comments won’t leave moderation.

  10. Brian Lynchehaun Post author

    My favourite part of people invested in hyperbolic conspiracy claims is where they demand that you prove their evidence-free claims wrong, and if you refuse to provide rock solid evidence that they’re wrong (which is normally impossible as they prefer to imply, as Mattrick did above, rather than explicitly state things), then you need to stop doing whatever you’re doing.

    In Mattrick’s closing statement of his not-going-to-be-published comment:

    If you think this is an irrational position for me to have, so be it, but if there is nothing you can do but roll your eyes at me, I suggest you consider changing to another website called compartmentalized thought: rudeness applied.

    That which is submitted without evidence, can be dismissed without evidence.

    Calling the fluoridation of the water system “mass medication of the population without consent” is just hyperbolic bullshit, and is the meat-and-potatoes of conspiracy cranks. While one could make the argument that this is ‘mass medication’, in terms of rhetoric it’s entirely an alarmist phrase: it makes teeth healthier. That’s it. Nothing more.

    To childishly demand every piece of trash that gets typed up be dealt with point by point? You don’t get to demand how I spend my time, and I refuse to waste it refuting drivel.

    You want me to respond to your points? Then bring research. To claim that it’s “not possible” to research these areas is to openly declare how little one has looked.

    To declare such on a post that includes a research paper on the topic is just idiotic.

Leave a Reply