Fluoridation – the IQ myth

fluoride_kills_test (1)Some of the myths promoted by anti-fluoridation activists really are of the “unsinkable rubber duck” variety. No matter how many times they are debunked they keep being repeated.

If you follow the fluoridation debate at all you will have come across the “Harvard Study” “proving” fluoride makes you dumb. It is often associated with the claim that the Nazis used fluoridated water supplies in their concentration camps to distract the inmates. Some will even claim that this is the purpose for fluoridation in the US!

I haven’t dealt with this particular myth yet, but really can’t do better than repeat this post from the US Life is Better with Teeth web site. (By the way, this is an excellent source of information on the fluoridation issue). The article is Fluoride and IQs


In July 2012, anti-fluoride activists circulated an article from a journal called Environmental Health Perspectives (EHP) to support their claim that fluoride lowers IQ scores in children. There are several reasons why the claim being made by opponents lacks credibility.

  • The EHP article reviewed studies on IQ scores for children living in areas of China, Mongolia and Iran where the water supplies have unusually high, natural fluoride levels. In many cases, the high-fluoride areas were significantly higher than the levels used to fluoridate public water systems in the U.S. In fact, the high-fluoride areas in these countries reached levels as high as 11.5 mg/L — more than 10 times higher than the optimal level used in the U.S.
  • This article offers a meta-analysis, and its credibility hinges on whether good-quality studies are reviewed. Yet the article’s co-authors admit that “each of the [studies] reviewed had deficiencies, in some cases rather serious, which limit the conclusions that can be drawn.” Although the studies compared high-fluoride with low-fluoride areas, the authors acknowledge that “the actual exposures of the individual children are not known.”
  • The two Harvard researchers who reviewed these studies have distanced themselves from the way in which anti-fluoride activists have misrepresented their article. After contacting these researchers, the Wichita Eagle newspaper reported, “While the studies the Harvard team reviewed did indicate that very high levels of fluoride could be linked to lower IQs among schoolchildren, the data is not particularly applicable here because it came from foreign sources where fluoride levels are multiple times higher than they are in American tap water.”
  • The Harvard researchers wrote in their article that the average standardized mean difference (0.45) in IQ scores “may be within the measurement error of IQ testing.” Despite web pages claiming that the article ”confirms” that fluoride reduces IQ scores, the Harvard co-authors did not reach a firm conclusion, writing instead that “our results support the possibility of adverse effects …” Indeed, their article called for more and better-quality research, including more “precise” data on the children involved and assurances that other factors have been ruled out as reasons for the IQ differences.
  • Given the small difference in IQ scores, it’s possible that arsenic levels, school quality, nutrition, parents’ educational levels or other factors could have shaped the results. The authors also added that “reports of lead concentrations in the study villages in China were not available”— another factor that could not be ruled out. A Britishresearch team reviewed similar Chinese studies, found “basic errors” in them, and reported that “water supplies may be contaminated with other chemicals such as arsenic, which may affect IQ.”
  • Between the 1940s and the 1990s, the average IQ scores of Americans improved 15 points.  This gain (approximately 3 IQ points per decade) came during the same period when fluoridation steadily expanded to serve millions and millions of additional Americans.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
Fluoridate our water Facebook page
New Zealanders for fluoridation Facebook page

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55 responses to “Fluoridation – the IQ myth

  1. “No physician in his right senses would prescribe for a person he has never met, whose medical history he does not know, a substance which is intended to create bodily change, with the advice: ‘Take as much as you like, but you will take it for the rest of your life because some children suffer from tooth decay. ‘ It is a preposterous notion.”

    Like

  2. jwillie6 – Quote marks – care to attribute and link – only polite?

    And then perhaps you could attempt a justification.

    Like

  3. Shouldn’t we just trust jwillie6? After all, it seems legit. Why bother with any fact-checking? Some anonymous guy on the internet shares some other anonymous person’s opinion. Well…alrighty then. ;)

    Liked by 1 person

  4. Apparently jeillie6 is a well established international troll – he or she can sniff out the F word within minutes if its internet appearance anywhere in the world.

    Like

  5. jwillie6 was quoting Dr. Peter Mansfield, a physician from the UK who was an advisory panel member on the ‘The York Review – A systematic review of public water fluoridation’ (McDonagh et al., 2000) on behalf of the UK government. A fairly reliable source I would think. This is the ethical issue that all local governments have been forced to consider. What justification is needed?

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  6. Out of idle curiosity, I followed one of the links for the anti-fluoride nutters.

    First we get the “shock, gasp” headline.
    (Hey, it’s traditional.)

    Breaking: Major Harvard Study Published in Federal Govt Journal Confirms Fluoride Lowers IQ

    Oh my stars and garters! Science overturned. Feel the Earth beneath your very feet shift from titanic forces etc. etc. etc.
    Straight away, one’s bullshit meter should start flashing.
    Could be true. Could be. But….probably not. Let’s have a closer look.

    If the scientific link between fluoride exposure and a noted decreased in IQ is a conspiracy theory, then perhaps the Harvard researchers who just confirmed such a link should be tarred and feathered by the ‘evidence-based’ medical media.

    How many times have we seen this before?

    “Hey, we’re no longer the cranks! SEE? We’ve got xyz backing us up now!
    We’re legit. Can’t call us kooks any more. If you call us kooks then your calling xyz kooks too. So there!”

    Ah huh. Sure. You’ve made it to the big time. Of course you have. Riiight. It’s just that, well, things get lost in translation. Someone tells something about someone else who tells someone about that other thing and…it all gets a little bit bendy by the time it gets to you personally.

    Getting your science information second-hand is stupid when, with a simple google search, you can skip the middle man entirely.

    The actual article give tiny, tiny little quotes from the original paper. Odd.
    Why not give a generous amount of space to the xyz study? Perhaps the bottom line where they give their conclusions in their own words, in context and in detail?
    No?
    You surprise me.

    So what are we actually reading here? It’s not the xyz nor their work. They are MIA. Nope. What we’ve got is some goober with a blog just name-dropping xyz for support and riding on their shirt-tails.
    What kind of a goober, you ask?
    Oh……the wonderful kind.

    He’s a “seeker of truth”.

    I shit you not. Check out his self-description and weep with laughter.

    Anthony is the Editor of NaturalSociety, producer, consultant, and seeker of truth. Anthony’s work has been read by millions worldwide and is routinely featured on major alternative and mainstream news website alike, like the powerful Drudge Report, NaturalNews, Infowars, and many others. Anthony has appeared, oftentimes routinely, on programs like Russia Today (RT), The Alex Jones Show, Coast to Coast AM, and others. Anthony is also a founding member of Natural Attitude and the creator of the independent political website.

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  7. So what is the justification, Ross? And is it at relevant to this post?

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  8. Christ, you would think people would try to hide that sort of information – not put it in their CV.

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  9. jwillie6 was quoting Dr.XYZ , a physician from the UK who was an advisory panel member on the !@# on behalf of the UK government. A fairly reliable source I would think.

    Then you need to think harder. It’s not the credentials that’s important. It’s the work. Stop meekly swallowing stuff from someone just because they flash their credentials at you.

    Wakefield’s a doctor. (Or at least he was.) Are you going to not vaccinate your children because of him?
    Deusberg’s a research scientist. A genuine big shot in his day before he went wierd. Are you going to become an AIDS denialist just on his say-so?

    Science is not about “the experts”. The personalities are irrelevent. It’s the work.

    Science Works! How the Scientific Peer Review Process works

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  10. So what is the justification, Ross? And is it at relevant to this post?

    Ross was helping you out by finding the attribution of the quote.
    Ross doesn’t know the relevance of the quote to the post since Ross didn’t post the original quote
    The original quote was posted by commenter jwillie6.

    jwillie6 is the provider of the Primary Source of Information. Ross is the provider of the explanation of the attribution of the quote by the was posted by jwillie6

    Therefore, I think Ross should receive some thanks for answering your question as to who wrote the quote posted by jwillie6,

    Like

  11. Ross said no justification was required which is of course a cop out. As it stands the statement is irrelevant to this post. So yes, I want to see how Ross justifies the statement. It’s called discussion.

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  12. I managed to Bing the quote and find it on this page

    http://www.healthfreedom.co.nz/fluoridation-free-nz/65-fluoride.html

    which may be used as a Primary Source of Information for any further discussions.
    There are several other similar quotes that may be placed within quotation marks and back-reference to this page to enable any further discussion; my interest is only in furthering the understanding of the random attribution of blog comments that are placed by random commenters on random blogs

    This may be an enabling platform for us ti collaborate and discuss the issues in a cooperative framework going forward

    Like

  13. Andy, you seem at a loss since Treadgold’s blog collapsed. I guess Richard Cummings is really not stimulating enough to for a sensible discussion.

    You will be helping blind people across the street next.

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  14. Hey, that’s not a primary source. It is rubbish.

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  15. It is not a primary source? What is a primary source?
    It is some kind of source, maybe a secondary or tertiary source,.

    But why the aggro? I found a quote that you asked about in a webpave using a search engine. I guess this is pretty close to helping blind people across the road, since you seem incapable of highlighting the text, right clicking and using the search with google feature

    If you don’t want people to comment on your blog then just go to the pub and watch rugby.

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  16. Or the Americas Cup, much more fun.

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  17. More fun than even Richard Cummings?

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  18. Badgers can be fun too

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  19. More fun than Richard?

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  20. I don’t know Ken. I don’t know how much “fun” Richard is, since I have never met him.
    You can have fun with Dicks though, as I am sure you know, so in general, the answer would be yes

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  21. I second Ken’s stating that jwille6 is an international fluoridation troll. His real name is James Reeves. He’s a retired engineer from the state of Louisiana in the deep South of the U.S.A
    I would venture that he spends 18 hours a day sniffing out any article in the World that has the “f word” in it.

    I am a Yank, have visited your country twice, and there’s no place that I’ve visited that I’ve said to my wife, “I could have been born a Kiwi”. Congrats to your America’s Cup win. 4 million Kiwi’s versus 300 million Americans.

    And keep the heat on the anti’s. Good luck in Hamilton with the upcoming vote. The whole public health World is watching…………

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  22. We haven’t won the America’s Cup yet.

    Like

  23. Also, it’s not “. 4 million Kiwi’s versus 300 million Americans.”, it’s one billion dollar corporation against another. The Kiwis like to think they are part of it, but they are not. (Unless the win of course, in which case we’ll all be celebrating, apart from Russell Coutts, who will down the Job Centre)

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  24. .Also, it’s not “. 4 million Kiwi’s versus 300 million Americans.”, it’s one billion dollar corporation against another.

    Almost true, in NZ the long suffering taxpayer stumps up most of the bill for the challenge, but gets none of the credit. Ah, NZ – where – for some inexplicable reason – yacht races and rugby games are routinely hailed as saviors of the economy.

    Like

  25. It’s probably a bargain compared with hosting the Olympics

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  26. “In conclusion, our results support the possibility of adverse effects of fluoride exposures on children’s neurodevelopment. ”
    Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis

    http://ehp.niehs.nih.gov/1104912/

    Like

  27. “the majority of the studies that the Harvard team reviewed investigated fluoride levels that are still considered “safe” in the United States. Of the twenty studies that investigated the effect of fluoride intake from water, twelve examined communities with a fluoride content less than 4 mg/l. This is a level that is still considered “safe” by the U.S. EPA. Every one of these twelve studies found reduced IQ in the “high-fluoride” community when compared to a low-fluoride community. ”

    http://fluoridealert.org/articles/iq-facts/

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  28. “Virtually no human studies in this field have been conducted in the U.S., said lead author Anna Choi, research scientist in the Department of Environmental Health at HSPH.”

    http://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/

    Like

  29. On March 22, 2006, the prestigious National Research Council of the National Academies of Science released a 450-page review of fluoride toxicity. The report, which was three years in the making, concluded that the safe drinking water standard for fluoride (4 ppm) causes significant damage to teeth, and places consumers at elevated risk for bone damage, including bone fracture and joint pain. Because of this, the NRC recommended that the fluoride safety standard be reduced. In addition to its concerns about tooth and bone damage, the NRC identified a range of other health effects that may be associated with fluoride exposure, including damage to the brain, disruption of the endocrine system (thyroid gland, pineal gland, glucose metabolism), and bone cancer.

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  30. Ken, perhaps yopu should read the discussion I had with Paul Connett – he is the main propoent of the IQ argument and it was covered in several of our articles.

    Could you tell us what document you are copy and pasting from? it will make the whole discussion simpler.

    meanwhile,. I will just take you up on a couple fo your claims.

    1: You claim (well, actually you quote the activist web site “Fluoride Alert) – ” Every one of these twelve studies found reduced IQ in the “high-fluoride” community when compared to a low-fluoride community.”

    Then what about the studies on this list by Li et al (2010) and Wang et al (2001) – they reported no significant difference between high fluoride and low fluoride samples?

    2: the conclusion you quote from Choi’s paper also mentioned the need to assess connfounders – this was essentially ignorted in most of the studies. A recent New Zealand study did include many confounders – it found that fluoridation did not infuence IQ but education and breast feeding did.

    3: It is suspicious that 2 of these studies were from Iran – the rest from China and not published in English. This reaises the swuspicion of a selection process – even if it is the nill effect.

    4: Choi et al acknowledged their review was not relevant to fluoridation. Similar the NRC report did not look at fluoridation levels, simply the question of lowering maximum concentrations from 4 to 2 ppm.

    5: Have you read eiuther the Choi paper or the NRC review? Or have you relied simply on a biased interpretation at Fluoride Alert?

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  31. fluoride-is-bad-4-u

    lol u all mad keep eating ur fluoride u dum dums obveeuslee ur iq is 2 low for u to see that its bad 4 u :3

    Just one area of negative effect: http://fluoridealert.org/issues/health/pineal-gland/
    All claims are fully cited and backed up by legitimate research. Fluoride should be completely opt-in, if you want to eat fluoride the local municipality should send you free fluoride tablets and not just put it into everyone’s water.

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  32. This article yet only picks out the shortcomings of one anti-flouride study, offering no evidence whatsoever that flouride doesn’t have negative mental health effects. Furthermore the author has the audacity to state that iq scores have increased since mandatory water flouridation has been implemented, yet isn’t it highly likely the iq increase is due advancements in education.

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  33. Shane, it is this particular study which is promoted by anti-fluoridationists as “proof” of a negative effect of fluoride a o it is logical that we should look at it and identify it’s failing. I have written further about this in http://openparachute.wordpress.com/2014/02/16/quality-and-selection-counts-in-fluoride-research/ and http://openparachute.wordpress.com/2014/02/20/repeating-bad-sicence-on-fluoride/. A sensible analysis of the literature does not indicate any negative effect of fluoridation on IQ. That is normally considered sufficient evidence in science.

    No one is suggesting fluoridation is the cause of increasing IQ – recent studies show no effect of fluoridation on IQ at all.

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  34. Christopher Atkinson

    Hi Shane.

    I may have got the wrong end of the schtick but, you seem to think fluoridated water has a negative effect on IQ?
    Which study/research do you think is the one that clinches it for you? :-)

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  35. Which study/research do you think is the one that clinches it for you?

    (grabs popcorn, gets comfy)

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  36. You are not addressing my point, and i assumed no “side” of the argument as I am just looking for reliable information on the matter.

    I just find it ironic in an annoying kind of way that an article that attacks the credibilty of one study would actualy be lacking in credibility in itself, just assuming that to debunk the notion that flouridation has negative effects a research paper/article would not only pointout the flaws in one study but offer peer reviewed information that was to the contrary.

    Pointing out limitations on one study does not prove anything, it only casts doubt on the ONE study.

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  37. just find it ironic in an annoying kind of way that an article that attacks the credibilty of one study would actualy be lacking in credibility in itself…

    Wait. What? Who says?

    Pointing out limitations on one study does not prove anything..

    Nothing?

    …it only casts doubt on the ONE study.

    Oh, you mean apart from that little thing?
    Ah.

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  38. Christopher Atkinson

    Hi Shane,
    “…I am just looking for reliable information on the matter”
    Really?
    You avoid my polite request by saying that I have not addressed your point.

    But to address you concern. In any scientific situation, remember – the onus of “proving” an assertion is “true” is on the side who asserts that it is true.

    In this case, it is the responsibility of those who believe that Fluoridated water causes low IQ (or anything else for that matter)
    There need not be any opposing studies to show that fluoridated water doesn’t cause low IQ – it is not possible to prove a negative (Bertrand Russell’s teapot etc).

    So, again, which study/research do you think is the one that clinches it for you? :-)

    Like

  39. Is there really need for such condesention, I could pick apart a terrible and innacurate study done on “lead levels in water number of females in a polpulation “. Would this prove that lead has no adverse effects.

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  40. Shane – if there is a study you refer to on Pb and females and it’s bad then pick it apart. But an intelligent person looks at all the research. And does this critically so they would support your picking it apart. The intelligent conclusion is that Pb is harmful because many studies show that.

    Now the case with F is the opposite. We are picking apart the meta survey of Choi because anti-fluoridation activists make claims based on it which are incorrect. Looking at the scientific literature critically and intelligently there is no credible evidence of harmful effect of CWF on IQ – quite the contrary.

    If your disagree why not refer to the studies which convince you of this?

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  41. Shane

    which study/research do you think is the one that clinches it for you?

    The question is still there, on the internet … effectively forever … it doesn’t look good to ignore it.

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  42. Christopher Atkinson

    Shane, I apologise if you feel I have been condescending.

    I would be interested however why you are so determined to find that fluoridated water is responsible for lowering IQ?
    Do you think it is the cause of other problems?

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  43. Christopher Atkinson

    Shane – where have you gone?

    I was hoping that you were actually genuine and we could have a constructive dialogue

    You said “…I could pick apart a terrible and inaccurate study done on…”

    Well…yes…perhaps, but it would be a shame to use this as a reason to avoid answering my question

    Condescending or otherwise (I can’t help how you interpret my simple and direct questions) and for the fourth time, can you provide any other studies that support the idea that fluoridated water has any effect on lowered IQ?

    Are you able to?

    Or will you resort to diverting the issue a few more times (which you have already) to progressing to accusations of me of being condescending (which you have already begun) to other equally silly reasons for not being able to answer a simple

    simple

    question

    If I have got things wrong, by all means point them out, I will apologise if I have got things wrong

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  44. There are studies out there that do cast doubt on the benefits of flouridated drinking water, and even the potential harm to people a simple search of many scientific databases will present you with various arguments, i could point you to this study since you are so persistantly asking me for a study on the negative effects. Even though i never assumed a “side” on the fluoride debate, only critisized this article.

    Campbell, A. W., M.D. (2013). Fluoride: What are the facts? Alternative Therapies in Health and Medicine, 19(5), 8-10.

    chronic toxicology is difficult by nature to measure accurately, especially being species specific.

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  45. There are studies out there that do cast doubt on the benefits of flouridated drinking water,

    (I’m sure Chris or Cedric deal with the switch and also the lack of link to citation)

    I’ll just let Shane mull over the observation:

    The studies “out there” are not convincing enough to cause any scientific, medical, public health or dental community of the planet to dispute the mainstream scientific consensus on the positive benefits to dental health of fluoridated drinking water. Not a single one.

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  46. Shane, there’s this thing called the burden of proof.

    …offering no evidence whatsoever that flouride doesn’t have negative mental health effects.

    There’s no reason to suspect that water fluoridation is harmful.
    For almost seventy years now, people in a wide variety of communities have had access to fluoridated water.
    There’s been a conspicuous absence of dead people…or birth defects….or IQ loss… or anything really.

    If you want to claim that “X” is dangerous then the burden of proof is on you.

    “…offering no evidence whatsoever that flouride doesn’t have negative vampire effects.”

    It’s put up or shut up.

    The burden of proof

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  47. Christopher Atkinson

    Hi Shane,

    Thank you for replying.

    “There are studies out there….”
    Yep…but it is only fair to reference specifics rather than point to a general collection of nonspecific flotsam – there is a mountain of rubbish out there.

    It also adds credibility to what you say, not only do we know what you are talking about, it gives the ability for everyone to comment on , criticize and otherwise discuss the merits of what you assert.

    You said ”… since you are so persistently asking me…”
    I am only asking you persistently as you are persistently avoiding my question!!

    It’s not a good look if you can’t/won’t/choose not to back up what you say.
    How can I take you seriously if you don’t take what you say seriously?

    I’ll have a look at the reference you provided – could you please provide a link in future? It makes it far easier to find.
    Cheers :-)

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  48. Christopher Atkinson

    Hi Shane,

    I had a brief look for the Jounal “Alternative Therapies in Health and Medicine” –

    By definition it is “alternative” and at a glance doesn’t follow the mainstream scientific method – not a credible souce to show anything of any value really.

    Do you take this seriously?
    How to you filter out the flotsam or do you prefer non scientific sources?

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  49. Christopher Atkinson

    Shane,

    I spent 10 minutes to find out that the author of the article you provided has some very dubious issues surrounding him;

    http://scholarlyoa.com/2013/12/26/a-medical-publisher-with-some-problems/

    If this source is reliable, it appears that he had numerous complaints made against him and is unable to practice medicine in Texas.

    There are also some very dodgy things going on around the publication of the journal’s he is the editor in chief of.

    I think you seriously need to vet/filter your sources before trying to rely upon the claims they make.

    Not a good look.
    :-(

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  50. Fact and source checking, not taught in Conspiracy 101.

    Nor in any other course offered by the Faculty of Oogity Boogity.

    Like

  51. Oh you guys are so mean and arrogant.

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  52. Steve Slott

    Damn! How’d I miss out on all this fun?? I gotta start paying better attention to my NZ pals!

    Steven D. Slott, DDS

    Like

  53. I truly appreciate your website! One year into our move from the city to the ‘burbs and I keep running into adults who “don’t believe” in science (like fluoridation and vaccines) – maybe the better explanation is they don’t believe in Public Health policies. As a scientist and an environmental engineer, that perspective is personally insulting. SO glad you developed this website – and specifically this article – so that I don’t have to. Cheers!

    Like

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