Debunking a “classic” fluoride-IQ paper by leading anti-fluoride propagandists


Three of the paper’s authors – Quanyong Xiang (1st Left), Paul Connett (2nd Left) and Bill Hirzy (far right) – preparing to bother the EPA.

Anti-fluoride groups and “natural”/alternative health groups and websites are currently promoting a new paper by several leading anti-fluoride propagandists. For two reasons:

  1. It’s about fluoride and IQ. The anti-fluoride movement recently decided to give priority to this issue in an attempt to get recognition of possible cognitive deficits, rather than dental fluorosis,  as the main negative health effect of community water fluoridation. They want to use the shonky sort of risk analysis presented in this paper to argue that harmful effects occur at much lower concentrations than currently accepted scientifically. Anti-fluoride guru, Paul Connett, has confidently predicted that this tactic will cause the end of community water fluoridation very soon!
  2. The authors are anti-fluoride luminaries – often described (by anti-fluoride activists) as world experts on community water fluoridation and world-class scientists. However, the scientific publication record for most of them is sparse and this often self-declared expertise is not actually recognised in the scientific community.

This is the paper – it is available to download as a pdf:

Hirzy, J. W., Connett, P., Xiang, Q., Spittle, B. J., & Kennedy, D. C. (2016). Developmental neurotoxicity of fluoride: a quantitative risk analysis towards establishing a safe daily dose of fluoride for children. Fluoride, 49(December), 379–400.


Co-author Bruce Spittle – Chief Editor of Fluoride – the journal of the International Society for Fluoride Research

I have been expecting publication of this paper for some time – Paul Connett indicated he was writing this paper during our debate in 2013/2014. FAN newsletters have from time to time lamented at the difficulty he and Bill Hirzy were having getting a journal to accept the paper. Connett felt reviewers’ feedback from these journals was biased. In the end, he has lumped for publication in Fluoride – which has a poor reputation because of its anti-fluoride bias and poor peer review. But, at last Connett and Hirzy have got their paper published and we can do our own evaluation of it.

The authors are:


Co-author David C. Kennedy – past president of the International Academy of Oral Medicine and Toxicology – an alternative dentist’s group.

Bill Hirzy, Paul Connett and Bruce Spittle are involved with the Fluoride Action Network (FAN), a political activist group which receives financial backing from the “natural”/alternative health industry. Bruce Spittle is also the  Chief Editor of Fluoride – the journal of the International Society for Fluoride Research Inc. (ISFR). David Kennedy is a Past President of the International Academy of Oral Medicine and Toxicology which is opposed to community water fluoridation.

Quanyong Xiang is a Chinese researcher who has published a number of papers on endemic fluorosis in China. He participated in the 2014 FAN conference where he spoke on endemic fluorosis in China.

xiang-Endemic fluorosis

Much of the anti-fluoridation propaganda used by activists relies on studies done in areas of endemic fluorosis. Slide from a presentation by Q. Xiang to an anti-fluoride meeting organised by Paul Connett’s Fluoride Action Network in 2014.

Critique of the paper

I have submitted a critique of this paper to the journal involved. Publication obviously takes some time (and, of course, it may be rejected).

However, if you want to read a draft of my submitted critique you can download a copy from Researchgate – Critique of a risk analysis aimed at establishing a safe dose of fluoride for children.  I am always interested in feedback – even (or especially) negative feedback – and you can give that in the comments section here or at Researchgate.

(Please note – uploading a document to Researchgate does not mean publication. It is simply an online place where documents can be stored. I try to keep copies of my documents there – unpublished as well as published. It is very convenient).

In my critique I deal with the following issues:

The authors have not established that fluoride is a cause of the cognitive deficits reported. What is the point in doing this sort of risk analysis if you don’t actually show that drinking water F is the major cause of cognitive deficits? Such an analysis is meaningless – even dangerous, as it diverts attention away from the real causes we should be concerned about.

All the reports of cognitive deficits cited by the authors are from areas of endemic fluorosis where drinking water fluoride concentrations are higher than where community water fluoridation is used. There are a whole range of health problems associated with dental and skeletal fluorosis of the severity found in areas of endemic fluorosis. These authors are simply extrapolating data from endemic areas without any justification.

The only report of negative health effects they cite from an area of community water fluoridation relates to attention deficit hyperactivity disorder (ADHD) and that paper does not consider important confounders. When these are considered the paper’s conclusions are found to be wrong – see ADHD linked to elevation not fluoridation, and ADHD link to fluoridation claim undermined again.

The data used by the Hirzy et al. (2016) are very poor. Although they claim that a single study from an area of endemic fluorosis shows a statistically significant correlation between IQ and drinking water fluoride that is not supported by any statistical analysis.

The statistically significant correlation of IQ with urinary fluoride they cite from that study explains only a very small fraction of the variability in IQ values (about 3%) suggesting that fluoride is not the major, or maybe not even a significant, factor for IQ. It is very likely that the correlation between IQ and water F would be any better.

Confounders like iodine, arsenic, lead, child age, parental income and parental education have not been properly considered – despite the claims made by Hirzy et al. (2016)

The authors base their analysis on manipulated data which disguises the poor relations of IQ to water fluoride. I have discussed this further in Connett fiddles the data on fluorideConnett & Hirzy do a shonky risk assessment for fluoride, and Connett misrepresents the fluoride and IQ data yet again.

Hirzy et al. (2016) devote a large part of their paper to critiquing Broadbent et al (2014) which showed no evidence of fluoride causing a decrease in IQ  using data from the Dunedin Multidisciplinary Health and Development Study. They obviously see it as a key obstacle to their analysis. Hirzy et al (2016) argue that dietary fluoride intake differences between the fluoridated and unfluoridated areas were too small to show an IQ effect. However, Hirzy et al (2016) rely on a motivated and speculative estimate of dietary intakes for their argument. And they ignore the fact the differences were large enough to show a beneficial effect of fluoride on oral health.


I conclude the authors did not provide sufficient evidence to warrant their calculation of a “safe dose.” They relied on manipulated data which disguised the poor relationship between drinking water fluoride and IQ. Their arguments for their “safe dose,” and against a major study showing no effect of community water fluoridation on IQ, are highly speculative and motivated.

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58 responses to “Debunking a “classic” fluoride-IQ paper by leading anti-fluoride propagandists

  1. The little guy on the left reminds me of Yoda from Star Wars.


  2. Ken though I wrote previously about the inadequacy of the term as you use it, “confounding,” you seem to hope readers have forgotten. You call iodine a confounding variable but it is actually an interacting variable. Here is some more explanation:


  3. Brian, whether there are interactions or not do you seriously support Hirzy et al’s claim that they have eliminated any influence of confounding variables – when they have not done any multiple regressions?

    And do you seriously suggest that a correlation explaining only 3% of the variance demonstrates a main effect when confounding factors are not considered?


  4. Ken it is a bit like low explanation of concrete strength is given by the amount of cement used unless the amount of water is also considered.

    Whar variance explanation do you have for that?


  5. So, Brian, you would advocate considering water and cement as factors in concrete strength – I, of course, agree. And, presumably, you would laugh at building a model based solely on simple correlation (perhaps with a correlation coefficient of 0.1) with temperature – without including water or cement in the statistical analysis?

    So what have you got against inclusion of important factors (in this case age is definitely one that should be included, but also things like birth weight, pregnancy term, etc.) in regression analyses involving IQ areas of endemic fluorosis?


  6. The variance of IQ with fluoride increases at high and low iodine levels. Otago, where the Broadbent study was done has more optimum iodine in water than Canterbury.


  7. Brian, you have absolutely no way of supporting that claim for Xiang’s data because it just wasn’t presented.

    But, seeing you are on your iodine hobby horse I would assume you would be supporting me. Xiang had the data for iodine and he could have included it in a multiple regression – but he didn’t – did he?

    Yet Hirzy and Connett claim that Xiang showed iodine was not a confounder!

    Why do you refuse to criticise such shonky claims?


  8. Ken, Hirzy et al. said: “Measurements by Xiang et al. of co-exposure to arsenic, the urinary iodine levels, and the blood-lead levels
    in the two villages indicated that the decrement
    in IQ seen in the high-fluoride children was unlikely to have been due to arsenic, iodine deficiency, or lead.”

    Do you see the Xiang iodine levels are above 130?

    Later Hirzy reports: “In the 2007–2008 National Health and Nutritional Examination Survey, Caldwell et al.44 found that about 5% of children aged 6–11 yr had a urinary iodine concentration of <50 µg/L. Urinary iodine levels of 20–49 µg/L indicate moderate iodine deficiency and levels <20 µg/L show severe deficiency. Thousands of US children fall into this sensitive subgroup of iodine deficiency. Since USEPA apparently intends to protect 99.5 percent of US children from severe dental fluorosis with a new MCLG, it is not unreasonable to expect that USEPA will take iodine insufficiency into account as a risk factor for IQ loss from
    fluoride as well." – Based on Lin FF et al.

    Hirzy is not claiming that Xiang thinks iodine does not affect IQ related to fluoride. He is just saying that Xiang's experiment was not investigating iodine levels that would show it.


  9. Ken it is not appropriate to try linear regression on segmented data. I talked about it before:

    I thought I had posted this graph but cannot find it on openparachute now:


  10. Hirzy is not claiming anything of the sort Brian. They are actually saying that IQ was correlated with water-F – yet they do not produce a single bit of evidence for that! Where are their correlation coefficients? I have searched high and low and even written to Xiang – with no response. I make this point in my critique and those authors are going to look very bad if they cannot come up with a correlation analysis.

    They did claim the correlation was not confounded by Iodine, Pb or As – yet again they produce no correlation coefficients or regression data.

    They rely only on the mean levels of I and Pb being not significantly different in the two villages. That is not a test for confuonding.

    It’s an extremely poor paper, scientifically. No wonder they couldn’t get it published in a reputable journal and had to lumol for Fluoride in the end.


  11. Brian, my statistician work colleagues always used to stress the importance of actually casting their eyes over the data before doing any analysis. This helped determine if a particular analysis was appropriate, if transformations were required, etc.

    You have absolutely no way of determining if linear regression was appropriate for any of Xiang’s data – except the urinary F vs IQ data where he actually presented it graphically in the paper.

    He provides correlation coefficients for some other regressions. But despite claiming a correlation with water F he does not present even the correalt6ion coefficient, let alone the data. I find this suspicious.

    One thing for sure – you have absolutely no right to comment here an claim that Xiang should or should not do a regression analysis without actually seeing his data.


  12. Ken I took some time reading Xiang’s figures from their graph.

    I gave a file a bit before Christmas 2015 on this thread:


  13. soundhill,

    Community Water Fluoridation has been present for decades, for generations, for millions of people worldwide.

    In the UK, USA, Europe, Australia, New Zealand, other places, exams have been taken by students, both before and after fluoridation, for even longer than CWF has been around.

    If CWF has an effect on IQ, the results will be obvious when comparing exam results from areas with and without CWF, areas before and after CWF.

    Show us the areas that demonstrate decrease in exam results after CWF was introduced… Or differences between comparable areas with/without CWF.

    It may be difficult. Educationalists are busy trying to explain the uniform improvement in exam results, whether or not CWF was present or introduced.


  14. The news that is coming up is the anti-fluoridationist petition to the EPA to get fluoridation stopped was rejected. Interesting because the Connetts gave it their best shot – 79 pages of scientific citations (misrepresented of course,) so the EPA rejection is very humiliating for the anti-fluoride people.

    Here is a quote from the EPA rejection:

    Fluoride Chemicals in Drinking Water; TSCA Section 21 Petition; Reasons for Agency Response page: 33,34

    “The petition has not set forth a scientifically defensible basis to conclude that any persons have suffered neurotoxic harm as a result of exposure to fluoride in the U.S. through the purposeful addition of fluoridation chemicals to drinking water or otherwise from fluoride exposure in the U.S. Still less has the petition set forth a scientifically defensible basis to estimate an aggregate loss of IQ points in the U.S, attributable to this use of fluoridation chemicals. As noted previously, EPA has determined the petition did not establish that fluoridation chemicals present an unreasonable risk of injury to health or the environment, arising from these chemical substances’ use to fluoridate drinking water. The fact that a purported risk relates to a large population is not a basis to relax otherwise applicable scientific standards in evaluating the evidence of that purported risk. EPA and other authoritative bodies have previously reviewed many of the studies cited as evidence of neurotoxic effects of fluoride in humans and found significant limitations in using them to draw conclusions on whether neurotoxicity is associated with fluoridation of drinking water. In contrast, the benefits of community water fluoridation have been demonstrated to reduce dental caries, which is one of the most common childhood diseases and continues to be problematic in all age groups. Left untreated, decay can cause pain, school absences, difficulty concentrating, and poor appearance, all contributing to decreased quality of life and ability to succeed.”


  15. Ken,

    In other words, lots of proven benefits for CWF.

    In contrast, there have been a few vague conjectures that there may be some kind of harm from CWF, but no-one has been able to substantiate those vague conjectures with something like actual evidence.


  16. Stuartg: “It may be difficult. Educationalists are busy trying to explain the uniform improvement in exam results, whether or not CWF was present or introduced.”

    You will have to verify that. You will need to give the scaling data of the old scholarship/bursary results and whether scaling has been adjusted at any stage after fluoridation.

    But I am also interested in all levels of attainment.


  17. soudhill,

    You don’t seem to understand. YOU claim CWF damages IQ, so YOU have to provide the evidence.

    I’ve merely shown you how you can use (publicly available) exam results in places with/without CWF to demonstrate what’s happening in the real world to the intelligence of real humans who experience CWF.

    There’s no need for you to cut and paste from shonky websites, hint, speculate, insinuate, or just plain guess, the data is already out there, merely awaiting your authoritarian analysis.


  18. Stuartg please verify your statement.


  19. Stuartg wrote: “Educationalists are busy trying to explain the uniform improvement in exam results, whether or not CWF was present or introduced.”

    “Uniform improvement” is not the same as “uniform attainment.”

    And here is one mechanism for improvement in exam results:

    “Universities are under pressure to be passing more students, and grade-scaling achieves that. One Victoria University academic we spoke to – he asked not to be named – explained how the University encourages academics to engineer their pass rates. “There is pressure, but they aren’t stupid about it, they’re not explicit. They try and get moderation systems in place, and I guess they communicate through the moderation systems to try and get the pass rates up. They’re obviously feeling the incentives.”

    By incentives, he’s talking about the Government’s Student Achievement Component funding. Of the University’s income last year, we estimate about $5 million was contingent on passing rates – about half of their operating surplus:”


  20. soundhill,

    You’ve said (or implied in the past) that it’s where the child was born and brought up that’s important with CWF – remember that messy speculation about rugby players of yours when you ignored all other sports including female rugby?

    So that rather suggests that university results (where students are from all over the country, if not the world) cannot be used to look at effects of CWF on intelligence.

    School students tend to be educated in the same locality as they live, drinking the same water at home and at school. Those are the students whose exam results you should be using to provide evidence for your speculations about CWF and IQ.

    Residential school students, including the Universities, do not have students from uniform backgrounds wrt CWF and so would be excluded from your definitive analysis.

    In the meantime, whilst you are preparing that definitive analysis of exam results with/without CWF, could you try explaining the uniform improvement in school exam pass rates in NZ, UK, USA, Australia… whether or not there is CWF? After all, you’re the one who has the faith/belief that CWF results in lowered IQ.


  21. Stuartg: “could you try explaining the uniform improvement in school exam pass rates in NZ, UK, USA, Australia… whether or not there is CWF?”

    Because there is more internal assessment and schools are trying to keep pass rates up to attract students, therefore funding. That applies in botfh CWF and non-CWF areas.

    Both CWF and non-CWF areas may have improved by the same percentage but if they were behind for a start the CWF areas will still be behind.


  22. soundhill,

    “Both CWF and non-CWF areas may have improved by the same percentage…”

    “may have” – or may not have? Have they, or haven’t they? Use evidence instead of your fantasy-based beliefs.

    I’ve pointed out how the data is available, on publicly accessible databases, so there’s no need for you to speculate any more. There’s also no need to copy/paste from your anti-fluoride cronies, either.

    The same databases will let you allow for confounding variables such as income, degree of deprivation, diet, ethnicity, dental services and yes, even your favourites such as iodine.

    Just get the data and do the analysis yourself. Then show us the evidence.

    Good solid evidence is what drives the use of CWF, not speculation based on shonky papers and websites.


  23. Stuartg wrote, (I wrote):
    “Both CWF and non-CWF areas may have improved by the same percentage…”

    “may have” – or may not have? Have they, or haven’t they? Use evidence instead of your fantasy-based beliefs.”

    So Stuartg, what did you mean when you wrote on the 23rd?:
    “Educationalists are busy trying to explain the uniform improvement in exam results, whether or not CWF was present or introduced”

    Uniform improvement? But not the same percentage? What then?


  24. soundhill,

    You believe, despite not having any evidence to support your belief, that CWF has an effect on human intelligence.

    Well, I’ve merely shown you how you can use publicly available, real world, human population data to produce evidence to either support or refute your fantasy/belief.

    It’s not up to me to do the work for you. If you don’t know how to do the work, It’s not my job to teach you. If you can’t understand or interpret the data, it’s still not my job to teach you.

    Maybe by attending some high school classes in science and statistics you would learn how to interpret that real world evidence?

    However, if you can’t even read blog comments accurately (where did I mention percentage?) then I suspect that you may have difficulty at school.

    And always remember, the person who makes a claim has to provide the evidence to support that claim.


  25. Stuartg wrote: “Educationalists are busy trying to explain the uniform improvement in exam results, whether or not CWF was present or introduced.”

    Please give evidence for your claim of what educationalists are trying to explain.


  26. soundhill,

    Giving an answer to that (which is easily looked up on the ‘net) will give you no assistance in finding data to support your belief that CWF inhibits human IQ.


  27. Stuartg please tell me which educationalists.


  28. soundhill,

    I made no claim. Improvement in exam results over time has been documented in many, many local and national government reports from many countries. A significant quantity of those reports are on the ‘net and there has been considerable debate about them.

    I can’t help it if you are unaware of the reports or the debates.

    Sheesh. I try to help by pointing out a way for you to get evidence to support or refute your claim that CWF lowers human intelligence, but all you do is deflect away from the claim! It’s almost as if you already know the evidence will refute your claim!


  29. Stuartg I can’t remember where you said I can look up exam results by city or school.

    Now you seem to be suggesting to readers it has already been tabulated by fluoridation presence or not.


  30. soundhill,

    Read back, just one comment. Rather than directing you to a single site, I gave you a general indication of where you could “look up exam results by city or school.”

    I said “Improvement in exam results over time has been documented in many, many local and national government reports from many countries. A significant quantity of those reports are on the ‘net.”

    I did not expect you to require lessons in the use of Google. Or are you limiting yourself with GoodGopher and Mercola for your searches?


  31. soundhill,

    You made a claim.

    You gave no evidence to back your claim, although decades of public health data and school results data would enable you to test your claim.

    I gave you general indications on how a scientist would go about testing that claim.

    I did that because you did not seem to know how or even why scientists are expected to test their claims

    It’s now up to you to do the work to test your claim. No-one else is going to do it for you.


  32. Stuartg you wrote:
    “Educationalists are busy trying to explain the uniform improvement in exam results, whether or not CWF was present or introduced.”

    And people are finding it boring that you keep on repeating the first part of that statement. Now please stop wasting our time and talk about the second part.


  33. Stuartg: “remember that messy speculation about rugby players of yours when you ignored all other sports including female rugby?”

    Why “messy”?
    I did include some soccer.

    no living All Black captains have come from our most populous city, born after fluoridation started in 1966. Kieran Read was born in non-fluoridated Drury.

    All Black Captain Place of birth Year of birth Fluoridated then
    Sam Cane Reporoa 1992, n
    Kieran Read Drury 1985 n
    Richie McCaw Oamaru 1980 n
    Jerry Collins Samoa 1980 n
    Aaron Mauger Chch 1980 n ? fluoridated Waimairi possibly 1/4 Chch at that stage.
    Tom Willis Dunedin 1979 f ? but not if Taieri/Mosgiel
    Rueben Thorne Chch 1975 n ? Waimairi
    Anton Oliver invercargill 1975 f 1963
    Taine Randell Hastings 1974 f 1953
    Tana Umaga LH 1973 n Petone?
    Justin Marshall Mataura 1973 n
    Todd Blackadder Rangiora 1971 n
    Ian Jones Whangerei 1967 n
    Zinzan Brooke Waiuku 1965 n
    Paul Henderson Bluff 1964 f 1963-80s
    John Mitchell Hawera 1964 n
    Mike Brewer Pukekohe 1964 n
    Sean Fitzpatrick Auck 1963 n
    Frank Bunce Auck 1962 n
    Grant Fox New Plymouth 1962 n
    Steve McDowell Rotorua 1961 n
    Albert Anderson Christchurch 1961 n
    Richard Loe Chch 1960 n
    David Kirk Wellington 1960 n 1965
    Gary Whetton Auck 1959 n 1966
    Joe Stanley Auck 1957 n
    Wayne Shelford Rotorua 1957 n

    Note Auckland-born (1975) All Black Jonah Lomu suffered from kidney failure.

    It may not be just the heat of the climate, however.

    Starting about 8 years after fluoridation started in Birmingham in 1970, they have had no more wins in football with unfluoridated Manchester in a contest which has been going on for a long time.

    After Timaru was fluoridated from 1973 to 1985, South Canterbury produced no more All Blacks after 1972 having produced 22 before that.

    (Richie McCaw born in unfluoridated area and did not play for South Canterbury)

    More of the Hawkes Bay Magpies are selected from the unfluoridated areas of Hawkes Bay.


  34. soundhill,

    So, you have a hypothesis about some rugby captains. Now you have to test the hypothesis. Eliminate your current list, because you used it to generate the hypothesis, and test the hypothesis using the next few decades of rugby captains. That’s how to do it scientifically.

    Alternatively, you could test it right now by looking at the past captains of junior, women and mixed teams.

    As to the football – you can also test the hypothesis right now. Eliminate the games used to generate the hypothesis. Use the games between multiple other teams from those same cities to test the hypothesis – use Manchester City, Aston Villa, women teams, multiple amateur teams, reserve teams.

    And don’t forget to include the matches between Manchester United and Birmingham City reserves!

    Two hypotheses, neither of them tested by their developer, even though there are very simple and easy ways to test them.

    Scientists develop ways to test their hypotheses.

    It reflects badly on your claims to scientific veracity that you have been unable to figure out simple ways to test your own hypotheses.

    That’s why I called it “messy speculation.”


  35. soundhill,

    You want me to expound on “whether or not CWF was present or introduced.”

    Simple rephrasing should suffice: CWF is not included in their discussions.


    You said: “Now you seem to be suggesting to readers it has already been tabulated by fluoridation presence or not.”

    No, I’m suggesting nothing. I’m saying that it’s your hypothesis, so you do the testing.

    A simple test of your hypothesis is correlating publicly available school exam results to the presence or absence of CWF, taking into account the dates of introduction of CWF, income, degree of deprivation, ethnicity, (even iodine intake if you like), all of which are public information.

    Maybe you could get a grant from FAN?

    I look forward to you publishing the results.


  36. Stuartg wrote: “Simple rephrasing should suffice: CWF is not included in their discussions.”

    But when you wrote: ““Educationalists are busy trying to explain the uniform improvement in exam results, whether or not CWF was present or introduced.”

    it doesn’t look like that, or it looks as if you have drawn a conclusion, which needs verification.


  37. soundhill,

    I admit, the way I wrote that phrase meant that it could have been interpreted in more than one way.

    Unfortunately that sometimes happens with English.

    I have now clarified my meaning.


  38. soundhill,

    Just a comment about your list of rugby players and fluoridated places.

    Auckland is now a large city. It used to be several cities and smaller townships – Auckland, Manukau, Waitakere, North Shore, Rodney, Howick, Papakura… As a consequence, it gets its water supplies from several sources. Its water distribution grid includes several isolated systems. Not all of those systems are fluoridated.

    CWF was introduced in Auckland in 1966 (your data). But when was CWF introduced to Manukau? Or Waitakere? Or any other of those previously independent localities that have merged to form the current Auckland?

    I once lived in a non-fluoridated area of Auckland (the original Auckland), well after 1966. Even now, that area still doesn’t have CWF!

    Does your list allow for this? Or are you merely seeing what you want to believe?

    In reality, allowing for the historical entities that have now become Auckland doesn’t matter for your current list. Where it will matter is when you develop further lists in order to test your hypothesis.

    To test your hypothesis, every name on your current list has to be excluded from the test because that list resulted in your hypothesis. You simply do not use data that generated a hypothesis to subsequently test the hypothesis. Every scientist knows that.


  39. No my hypothesis came from how strong teams have come from Canterbury.

    But I noted the Brisbane Reds beat the Canterbury Crusaders after they had had fluoridation there for 3 years. I asked would they still beat them in 2014 after they had had it for 6 years. But Richie McCaw gave away a penalty near the end and the Reds won by 1 point.

    Now after 8 years of fluoridation in Brisbane the Reds are at position 15 on the Super Rugby ladder: the lowest they have been.


  40. My fluoridation data come mainly from:

    though for some parts of Auckland, such as Drury (Kieran Read), I contacted the Watercare and the old part of Drury was not fluoridated

    And I do have question marks because part of a city can be fluoridated as for Waimairi in Christchurch and contrarily Taieri in Dunedin isn’t.


  41. soundhill,

    I’m not talking peripheral areas of Auckland – try Onehunga.

    Maybe your anti-fluoride website source isn’t as accurate as the council data is?

    As for Taieri being part of Dunedin? About as much as Rolleston, Rangiora and Darfield are part of Christchurch. Or Paraparaumu and Otaki are part of Wellington.

    It just means that you will have to be very careful with testing your hypotheses. You cannot rely on cut-and-paste from your anti-fluoride websites but will actually have to evaluate the data yourself. (Maybe you wouldn’t get a grant from FAN after all?)


  42. soundhill,

    You said: “But I noted the Brisbane Reds beat the Canterbury Crusaders after they had had fluoridation there for 3 years. I asked would they still beat them in 2014 after they had had it for 6 years.”

    So, according to that statement, it doesn’t matter about CWF where a person was born, it’s all about where they currently live or play their sport.

    What, then, was the point of producing your list of birth places?

    Yo need to make up your mind about your hypothesis before you test it. You have to decide at which stage of life CWF has its putated effects: before birth, at birth, infancy, toddler, primary school, secondary school, early adulthood, or current stage of life (including training and playing sports).

    You seem to be confirming my opinion that so far all you have is messy speculation.


  43. soundhill,

    I previously suggested that anti-fluoride websites may not be the most reliable to determine whether a municipal water supply is fluoridated or not.

    Maybe checking with the local government will be more accurate?

    Take Manchester as an example. Your hypothesis appears to be along the lines of “Manchester United keeps beating Birmingham City because Manchester is fluoride free”. Well, there’s no need to test that hypothesis any more.

    A two minute check of the Manchester water supply web site shows that Manchester has CWF.

    Obviously, because both cities have CWF, you’ll need to search for another potential cause of the discrepancy in results. Personally, I’d consider the differences between club income and hence greater ability of Manchester United to purchase players is likely to be the most significant difference.


  44. Yes, I’ve seen my error – wrong Manchester!


  45. …Although United Utilities, the company that supplies water to much of the UK’s Northwest, does fluoridate some areas, it doesn’t yet include Manchester.

    Your hypothesis testing still needs to be done, soundhill!


  46. Stuartg: “As for Taieri being part of Dunedin? About as much as Rolleston, Rangiora and Darfield are part of Christchurch. Or Paraparaumu and Otaki are part of Wellington.”

    Taieri (Mosgiel) is 15 km from Dunedin
    scarcely more than from Sumner to Christchurch

    Otaki is 70km from Wellington
    Rangiora is 30km from Christchurch
    Rolleston is 23 km from Christchurch

    Mosgiel was a source if “control” subjects in the Broadbent “Dunedin” study

    I am being fairly careful.

    FFNZ “Is my town fluoridated?” says Onehunga and Huia Village not fluoridated.

    Interesting that All Black coaches Sreve Hansen and Ian Foster went to Taieri HIgh School.

    I had a question mark by Tom Willis. I see his father Eion lives in Sr Clair so he possibly comes from the fluoridated area.

    To satisfy you, Stuartg I see I am going to have to have several investigation for effect of fluoride at different ages and sexes and types of sport.

    The eight-year lag for Birmingham and Brisbane to fall back in soccer or rugby after fluoridation could mean there be an affect on developing players for both rugby and soccer.


  47. soundhill,

    It’s not to satisfy me. It’s about how science works.

    You just don’t seem to get it. Maybe it’s because, by your own declaration, you’ve never been taught about how science works?

    You’ve produced, or nearly produced, some hypotheses which you frequently like to mention.

    The next step in science, or even in common sense, is to test those hypotheses.

    We’ve been hearing about these hypotheses from you for years – but you’ve done nothing further about them. You’ve never managed to take the next, obvious, step and test them.

    I’ve assumed that you haven’t been able to figure out how to test those hypotheses, which is why you haven’t done anything about them.

    Well, now I’ve shown you some simple ways to test those hypotheses. It’s now your responsibility to test them, no-one else’s.

    The next time you mention them, particularly the messy speculation about sports, should be when you publish the results of your testing and can confirm or refute the conjectured association by using evidence.


  48. soundhill,

    Finish your speculations and say exactly what your hypothesis is. Then test it.

    It’s very difficult to test a hypothesis when the person who comes up with it can’t clearly tell others what the hypothesis is.

    Does the fluoride effect you postulate occur because of CWF at birth (your list of NZ birthplaces), or because of CWF right now (your football results, with MUFC purchasing the best players from around the world)?

    You seem to be very muddled with your thinking, vaccillating from one to the other, with occasional excursions to some time between the two.

    Before you can test your hypothesis, you need to be certain what your hypothesis actually is.

    However, even without you knowing what your hypothesis actually is, I’ve told you simple ways to determine whether you’ve seen coincidence or there really is an association.


  49. Stuartg wrote: “You seem to be very muddled with your thinking, vaccillating from one to the other, with occasional excursions to some time between the two.”

    All neonatal and childhood-adolescent years are a time of development – a doctor should know which means you are trying to be tricky.

    As with ionising radiation everyone can be affected but yourg ones are more debilitated.


  50. soundhill,

    I seriously suggest that you decide on a specific period of life that you suggest, or even hypothesise, that CWF can have an effect on sporting prowess.

    Being vague about the age at which a putative stimulus is supposed to have an influence on a person’s life merely serves to increase the messiness of your speculation.

    If you have no idea at which point in a person’s life that CWF is supposed to have an effect on sporting prowess, how do you expect anyone to take your speculation seriously?

    It makes it much easier to test a hypothesis when the person who produces a hypothesis can actually state what the hypothesis is.

    Are you actually able to state your hypothesis? Or must we repeatedly be fed this messy speculation?

    As it is, it seems that you’re the one being tricky, refusing to define your hypothesis because you’re beginning to realise that, to all intents and purposes, it’s already implausible.

    Haven’t you realised that, if you follow along this path of increasing obfuscation, you’ll end up stating something like “But we haven’t tested for the effect at seventeen years, thirty-four weeks and three days”?


  51. soundhill,

    If CWF affects sporting prowess at birth, then birthplace is important and you can test for where current sporting superstars were born. You can ignore where they live at the time of their prowess. That’s your rugby example.

    If CWF affects sporting prowess according to where the sporting superstars live, then you can ignore where they were born. That’s your MUFC vs BCFC example (provided we ignore the games between reserves and those of MCFC vs AVFC).

    Haven’t you noticed that your two examples contradict each other?

    Further, if CWF affects sporting prowess during formative years, as in your last comment, then you need to document CWF for each sporting superstar during preschool years. Or kindergarten. Or primary school. Or intermediate school. Or secondary school. Or university. Or maybe all of them? Depends on which part of the formative years you consider CWF has its effect. I note that you haven’t provided examples for any of these formative years, but a scientist really would have considered these options in their speculations.

    If CWF has to have its effect on sporting prowess throughout the entire of life, then you need to consider complications such as when a person living in a CWF area holidayed in a non-CWF area. Or vice versa. Or moved from an area with CWF to an area without. Or vice versa. And what happens if they move back again? What if they’re continually moving back and forward between areas, over multiple years, as happens with most of the players of MUFC and BCFC?

    All told, soundhill, it’s much easier if you decide on a specific time of life that CWF is supposed to have an effect on sporting prowess.

    At least you’d have a chance at testing your hypothesis.


  52. Stuartg: “All told, soundhill, it’s much easier if you decide on a specific time of life that CWF is supposed to have an effect on sporting prowess.”

    So you have a hypothesis that it can only affect it at one point


  53. soundhill,

    No, just trying to help you.

    If you are trying to say that CWF has an effect on sporting prowess, no matter when in life it was ingested, no matter the quantity ingested, contrasting it with the amount of non-CWF drunk (including bottled water and soft drinks…), then the amount of data required to test your idea becomes unobtainable. And even if you could get the data, a massive supercomputer would not be able to sort it’s way through the mess.

    If that’s the case, then you might as well say your idea is untestable and just shut up about it.

    Much better to provide a hypothesis that CWF has an effect on sporting prowess at a specific time of life, like you originally seemed to have with rugby. It was when you started to contradict yourself when trying to enlarge upon your original idea by increasing the times of life the putated effect could occur that it all became messy speculation.

    If you want people to pay more than glancing attention to your speculation, then you’ve got to demonstrate a correlation between CWF and sporting prowess.

    To do that, you’ve got to have a tested hypothesis.

    To test a hypothesis, first you have to produce a hypothesis to test.

    So far you haven’t been capable of doing that.

    So, right now, all you have an is idea. You haven’t yet turned it into a testable hypothesis. Once a tested hypothesis shows a valid correlation, only then is further investigation to determine the validity of the correlation appropriate. Even then there will be lots of discussion occurring over “proof”.

    Right now, you seem to have gone straight from having the idea to believing that your idea is already established science! You seem to have decided your idea doesn’t actually need to be tested.

    Until you produce a hypothesis that can be tested your idea will remain messy speculation.

    It’s now up to you…


  54. From 1929, the start of Jubilee rugby competition, to the time of fluoridation of most of Wellington, though not Petone which hasn’t been, Petone won 23% of the years. After fluoridation (and up until the time of the complicating closure of their secondary school and movement of Petone pupils to school across the river in fluoridated area) Petone won 43% of years.

    I can’t know at what age players would be being affected.

    It’s another “coincidence” of fluoridation correlated to reduced top rugby or soccer performance and the coincidences are mounting up.


  55. soundhill,

    “the coincidences are mounting up” – so the obvious question is: why don’t you test them?

    Anyone who knows anything about science knows that coincidences occur and can be disregarded. Apparently you don’t. But it’s only when testing suggests that events are not coincidental that they become significant.

    This messy speculation of yours isn’t impressing anyone. It’s not adding to your ideas, it’s just demonstrating the degree of your confusion about them. Neither is it improving anyone’s opinion of your expertise in the field of science.

    You’re detracting from your previous speculations by increasing your suppositions and guesswork. Especially when you talk about coincidence. It makes scientists think there must be nothing behind your speculation, otherwise you would have tested it by now.

    The best thing for you to do now would be to shut up about the whole subject until you have actually managed to formulate a hypothesis and then test it.

    You seem to think that I’m trying to attack your ideas. Read back. I’m trying to help you over the confusion you have about them. I’m trying to help you formulate and develop them into a hypothesis that can be tested to see if they are just coincidence or not. I’m trying to give you information and pointers as to how, once you have actually managed to formulate a hypothesis, you can go about testing the hypothesis.

    You now have sufficient information to formulate your hypothesis and then test it. So now we can expect you to shut up and actually do some work on your messy speculations – unless, of course, your entire purpose is FUD about CWF.


  56. Stuartg: ““the coincidences are mounting up” – so the obvious question is: why don’t you test them?”

    It’s a bit like asking an earthquake scientist why they don’t test their hypotheses. Say it is noticed by someone that damage occurs at the junction between rigid and flexible parts of structures. You say it is just coincidence go away and test it.

    The tell you a lot of examples that they know of then you say all that is to generate your hypothesis, do not include that in the testing. So you are making them wait for another big quake. Very convenient.


  57. soundhill,

    Earthquake scientist do test their hypotheses. Perhaps you haven’t noticed their forecasts of aftershock intensity and frequency following the earthquakes at Christchurch? Or Seddon? Or Kaikoura? Or even Murchison, way back in 1929? They’ve been all over the national news in various media, so not exactly easy to miss. Those forecasts are according to their hypotheses and theories. Each forecast has been a test of their hypotheses and theories.

    Maybe you haven’t noticed the news items about structural engineers testing their hypotheses about where the weak parts of structures in an earthquake actually are? About their subsequent hypotheses and theories of earthquake isolation? Their theories of how to protect structures and people in them during an earthquake?

    Are you saying that these forecasts and structural tests by earthquake scientists and structural engineers are all coincidence?

    By discounting these tests of hypothesis and theory, are you implying that your messy speculation about CWF and sporting prowess is merely pointing out coincidences? That it’s impossible to test your speculations?

    I don’t believe that’s what you mean.

    Every scientist knows that your speculations can be tested, even though you apparently don’t think so. I’ve actually informed you of various ways to test several of your speculations.

    I repeat: You now have sufficient information to formulate your hypothesis and then test it. So now we can expect you to shut up and actually do some work on your messy speculations – unless, of course, your entire purpose is FUD about CWF.


  58. Pingback: Anti-fluoridation campaigners often use statistical significance to confirm bias – The Science Page

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