Category Archives: SciBlogs

No; a new study from Ethiopia does not indicate fluoridation is bad for your bones

Anti-fluoride activists are continually citing scientific studies from areas of endemic fluorosis where dietary F intake is very high in their propaganda against community water fluoridation where F intake is low. Image credit: Science in the age of fake news

Anti-fluoride propagandists on social media have got into a bit of a frenzy about a new study using sonic scans to estimate bone quality. The propagandists are using it as “evidence” against community water fluoridation (CWF). But it simply is not relevant. The Ethiopian study looked at drinking water fluoride and urinary fluoride concentrations up to 15.5 mg/L whereas the fluoride concentration of drinking water in areas where CWF is used is about 0.5 mg/L

The study is:

Godebo, T. R., Jeuland, M., Tekle-Haimanot, R., Shankar, A., Alemayehu, B., Assefa, G., … Wolfe, A. (2020). Bone quality in fluoride-exposed populations: A novel application of the ultrasonic method. Bone Reports, 12(November 2019), 100235. https://doi.org/10.1016/j.bonr.2019.100235

The technique used by these researchers “measures the speed of sound waves (SOS) in bone, as influenced by a combination of bone parameters (e.g., microstructure, collagen composition, cortical thickness, and bone density) that are related to bone quality.” The SOS is reported in m/s.

Drinking water fluoride

Anti-fluoride activists have been citing this paper and telling councils in North America that fluoridation will lead to a decrease in bone quality of 15.8 m/s (measured by the sonic scanning method) for every 1 mg/L increase in drinking water F. This figure is taken from the abstract – “a 1 mg/L increase in F- in drinking water was related to a reduction of 15.8 m/s (95% CI: −21.3 to −10.3)” and is based on a fluoride concentration range of 0 to 15.5 mg/L. The relationship is shown in this figure from the paper:

SOS in all adults and F- concentrations in corresponding community water sources (r = 0.45, p < 0.0001).

But, of course, these drinking water concentrations are very much larger than anyone experiences where there is CWF. So I have extracted the data for the lower concentration levels – up to 4 mg/L. Still far too high for CWF. The resulting data shows no significant effect of drinking water fluoridation on bone quality:

SOS in all adults and F- concentrations in corresponding community water sources for lower drinking water F concentrations more relevant to CWF

The positive relationship (B= 12.326, 95% CI=-15.5, 40.1) is not statistically significant. The data does not show any effect of CWF on bone quality.

Urinary fluoride

The paper reported a similar situation for urine F – 24-hour collection. This is the figure from the paper:

Association between F- concentrations in drinking water and tibia SOS measures (r =0.36; p < 0.0001).

The anti-fluoride propagandist will quote the abstract of the paper:

“A 1 mg/L increase in 24-h urinary F-(range: 0.04–39.5 mg/L) was linked to a reduction of 8.4 m/s (95% CI: −12.7, −4.12) of adult tibial SOS.”

but, of course, those urine-F concentrations are very much higher than observed where CWF is used. Restricting the data to urine F concentrations lower than about 3.5 mg/L produces the following figure:

SOS in all adults and urinary-F concentrations in corresponding community water sources for lower urinary-F F concentrations more relevant to CWF

The negative relationship (B= -4.85, 95% CI=-54.37, 44.67) is not statistically significant. The data does not show any effect of CWF on bone quality. Urinary F data for people in areas where CWF is used is not well defined but values are generally less than 2 mg/L.

But the dedicated anti-fluoride activist doesn’t care about the facts

Health problems are common in areas of endemic fluorosis where dietary fluoride intake is excessive. This is a real problem in areas of the Middle East, Africa, China and India. Even in parts of Europe. So, of course, there are published scientific studies of these problems and it is not hard to find papers relating health problems to dietary fluoride intake.

But none of those studies are relevant to areas where CWF is used because dietary fluoride intake is very much lower.

That doesn’t stop dedicated anti-fluoride activists. They simply wildly exaggerate their claims – for example, they claim there are hundreds of studies showing that fluoride lowers the IQ of children but never mention that the overwhelming majority of those studies were made in areas of endemic fluorosis so are just not relevant to CWF

There is only a very small handful of studies possibly suggesting health problems from CWF. But all these are weak, suffer from poor statistical analysis or have produced conflicting and contradictory results. I mention some of these recent studies in my article What are the recent fluoride-IQ studies really saying about community water fluoridation?

Of course, these studies must be discussed – but they need to be discussed critically and intelligently. Not simply promoted together with the host of studies from areas of endemic fluorosis as an argument for stopping CWF.

It is the nature of social media that these sort of fake claims are easily promoted by anti-fluoride and anti-vaccination activists. The bone quality study discussed here is currently being pushed via Twitter to councillors in North American local governments. There are no attempts to analyse this or other studies – simply to promote them as “evidence” of problems with CWF

Social media is not going to go away and it is the responsibility of people in public office and policymakers to take such ideologically-motivated propaganda with a healthy grain of salt. All such claims need to be critically analysed. If the councillors receiving this information do not feel capable of making this analysis they should call on experts for advice.

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Anti-fluoridationists put faith in new “strong” studies to provide evidence missing in draft NTP review

The US National Academies of Science (NAS) found the National Toxicity Programme’s (NTP) conclusion in their recent draft report that fluoride is neurotoxic was not supported by the reviewed evidence (see Another embarrassment for anti-fluoride campaigners as neurotoxic claim found not to be justified). This was a huge defeat for anti-fluoride activists who had been roundly promoting the conclusion of the draft report – despite the warning on every page that it “should not be construed to represent any NTP determination or policy” and that the draft had been “distributed solely for the purpose of pre-dissemination peer review.”

So the anti-fluoridationists declared belief that the NTP draft was going to mean the end of community water fluoridation (CWF) was dashed. But that has not stopped Paul Connett, head of the main US anti-fluoride group Fluoride Action Network (FAN) from putting his own spin on the NAS peer review report. In his attempt to present this huge defeat as somehow positive he issued a press release where he claims:

“If the recommendations are adopted, they will make the final report ‘iron-clad’ against criticisms. The NAS suggestions should strengthen the draft report’s conclusion that fluoride is a presumed neurotoxin in children, which is based on 149 human studies. This finding brings into question the long-standing assurances from public health officials that water fluoridation is safe.”

The NAS peer review is very critical – and not just about the fact that the draft conclusion was not supported by the reviewed evidence. There are criticisms of biased study selection, insufficient consideration of the effect of confounders and problems with statistical analyses used. But besides playing with words to misrepresent the peer review, Paul Connett has declared a belief that the NTP will now consider new studies, published since the draft report was released, and these will provide the evidence missing in the original draft. He is hoping the revised review will include new “strong” (in his opinion) studies which will finally swing things his way:

“Multiple strong scientific studies, at exposures relevant to fluoridation, have been published after the NTP’s review. They link fluoridation in Canada to greatly lowered IQ in formula-fed infants (Till 2020) and 300% higher rates of ADHD (Ridell 2019); fluoridation in USA with sleep disturbances in adolescents (Malin 2020); and fluoride with lower IQ by thyroid disruption (Wang 2020).”

Notably, Connett actively ignores, yet again, a new study which does not fit his bias because it reports a positive relationship between maternal prenatal urinary F and child IQ – the complete opposite of what he wishes (see The anti-fluoride brigade won’t be erecting billboards about this study). But Connett has been specific so we can objectively consider just how strong or weak these new studies are and evaluate for ourselves the likelihood that they can be used to provide support for the unwarranted conclusion expressed in the draft NTP report.

I have discussed several of these studies in previous articles but briefly consider them together here.

Till et al (2020) formula-fed child study

I discussed this study in my article Anti-fluoride propagandists appear not to read the articles they promoteIt’s citation is:

Till, C., Green, R., Flora, D., Hornung, R., Martinez-mier, E. A., Blazer, M., … Lanphear, B. (2020). Fluoride exposure from infant formula and child IQ in a Canadian birth cohort. Environment International, 134(September 2019), 105315.

This has been blindly promoted by anti-fluoride propagandists as finding a decrease in IQ for children formula-fed as babies and a negative relationship of IQ for these children with drinking water F. However, the relationships are not statistically significant. It’s possible those anti-fluoride activists claiming a significant relationship had been influenced by Till’s previous conference paper where she indulged in special pleading for a non-significant relationship.

The findings reported by Till et al (2020) are summarised below:

While there are no significant relationships for IQ (FSIQ – Full-Scale IQ), the authors did report a significant negative relationship of performance IQ (PIQ) with water fluoride for children both breastfed and formula-fed as babies (and also for estimated F-intake for formula). Strangely, the anti-fluoride promoters of this paper generally don’t refer to this – perhaps because very few of them actually read the papers they promote.

Why there is a difference between IQ and PIQ is a bit of a mystery but there is a recommendation that PIQ, a subset of IQ tests, should not be used for clinical decision making because it is not consistent with current standards (see Beware of scientific paper abstracts – read the full text to avoid being fooled).

Riddell et al (2018) ADHD study

My article ADHD and fluoride – wishful thinking supported by statistical manipulation? discussed this study. Its citation is:

Riddell, J. K., Malin, A., Flora, D., McCague, H., & Till, C. (2019). Association of water fluoride and urinary fluoride concentrations with Attention Deficit Hyperactivity Disorder in Canadian Youth. Submitted to Environment International, 133(May), 105190.

The authors expressed disappointment that they could not find any relationship of ADHD prevalence to urinary F which they considered the best measure of F exposure. However, they were able to squeeze out some significant relationships with water F when the data was divided according to youth age. Significant for older youth but not younger. The findings of Riuddell et al (2019) are summarised in this figure.

The relationships are tenuous with large confidence intervals indicating their weakness. Manipulation of the data by age to find significant relationships reminds me of the saying that if data is tortured enough it will produce the answer you want

So, again, hardly a “strong” study and I cannot see Connett’s wish that the NTP will be able to justify its unwarranted draft conclusion with this.

Malin et al (2020) sleep “disturbances” study

I reviewed this study in my article Sleep disorders and fluoride: dredging data to confirm a bias. The paper citation is:

Malin, A. J., Bose, S., Busgang, S. A., Gennings, C., Thorpy, M., Wright, R. O., … Arora, M. (2019). Fluoride exposure and sleep patterns among older adolescents in the United States: a cross-sectional study of NHANES 2015 – 2016. Environmental Health, 1–9.

First of all, this paper has been poorly peer-reviewed. Effectively just an “in-house” review by coworkers all involved in publishing the same work (see Some fluoride-IQ researchers seem to be taking in each other’s laundry). This figure illustrates the relationships between the authors and their coworkers working with the same and similar data:

Relationships between Malin and her peer reviewers as indicated by joint publications. Links to the papers listed from the top are: Malin & Till (2015) Thomas et al (2014)Bashash et al (2017)Marlin et al (2018), Malin et al (2018)Bashash et al (2018)Thomas et al (2018), and Riddell et al (2018)

I think this sort of self-selected peer-review during journal publication is almost scientifically corrupt. In my article, I concluded that the journal was chosen for publication and the absence of genuine peer review, together with the weak findings, indicated  this is another poor quality paper on fluoride and health effects which make unwarranted claims – and which will be used by anti-fluoride activists in their campaign against community water fluoridation.”

The study used a range of parameters which facilitated dredging of the data to find apparently statistically significant relationships (see  Statistical manipulation to get publishable results). None of the relationships with blood plasma F were statistically significant (despite a bit of special pleading by the authors). They did report significant relationships with water F for sleep apnea, snoring, bedtime and waketime. An apparent reduction of snoring with an increase in water F baffled the authors. The confidence interval for sleep apnea was very large and small differences in bedtime and wake time are easily understood as connected with social differences between rural and city residents. There were no relationships with sleep duration.

So much for Connett’s description of this as a “strong scientific study” capable of reinstalling NTP confidence in their unsupported draft conclusion of a neurotoxic effect of fluoride.

Wang et al (2020) IQ study

This study is reported in:

Wang, M., Liu, L., Li, H., Li, Y., Liu, H., Hou, C., … Wang, A. (2020). Thyroid function, intelligence, and low-moderate fluoride exposure among Chinese school-age children. Environment International, 134(September 2019), 105229. https://doi.org/10.1016/j.envint.2019.105229

Although Connett claims the study was “at exposures relevant to fluoridation” this is not so. The study was aimed at measuring “low-moderate fluoride exposure affects” in the Chinese context and involved comparison of children from areas of “endemic and non-endemic fluorosis areas in Tianjin, China.” Water fluoride concentrations ranged from 0.20 to 3.90 mg/L and urinary F from 0.01 to 5.54 mg/L. Not at all comparable to the concentration where community water fluoridation (CWF) is present.

However, the study did separate results into different quartiles according to water F and urinary F concentrations and the data for the lowest quartiles are worth considering because they are for concentrations similar to that present where CWF is used.

I have extracted that data for quartile 2 of water F (0.7 to 1.00 mg/L) – a bit high compared with CWF but the data for the more relevant quartile 1 was not presented. Also the data for the second and third quartile of urinary F (UF) with the ranges 0.15 to 0.41 mg/L and 0.451 top 2.28 mg/L. Again these values are high.

Linear regression in these ranges showed no significant relationship of child IQ with either water F or Urinary F (UF) (see figure below). So much for Connett’s claim that this is a “strong scientific studies, at exposures relevant to fluoridation” that will lead to the NTP strengthening the NTP’s unsupported draft conclusion of a neurotoxic effect.

The elephant in the room – Santa-marina et al (2019)

Of course, Connett studiously ignores this study because it reported a positive relationship between maternal prenatal urinary F and child IQ (see The anti-fluoride brigade won’t be erecting billboards about this study).

The citation for this study is:

Santa-Marina, L., Jimenez-Zabala, A., Molinuevo, A., Lopez-Espinosa, M., Villanueva, C., Riano, I., … Ibarluzea, J. (2019). Fluorinated water consumption in pregnancy and neuropsychological development of children at 14 months and 4 years of age. Environmental Epidemiology, 3.

I have summarised the findings reported by Santa Marina et al (2019) below. These are certainly not going to provide any hope to Connett that the unsupported NTP conclusion will somehow be retrieved.

Conclusions

Connett is simply attempting, in his press release, to put a brave face on the embarrassment of the NAS peer review report. He and his supporters had been actively promoting the unsupported conclusion of the draft report – even suggesting it would shortly lead to the end of CWF. So a public embarrassment and he responds by holding out hope that his position will be retrieved by new studies.

His reliance on new studies is effectively an acknowledgement that the studies considered by the NTP were not adequate for the draft conclusion presented. However, he is wrong to describe these studies as “strong.” They are actually very weak and are hardly likely to change the final NTP assessment. He has also actively ignored, and hidden, the fact that the new studies are contradictory (Santa-marina et al 2019 produced the opposite result to what Connett wants) and conflicting (the different studies rely on different measures of cognitive ability and fluoride intake as well as manipulation of the data to find significant relationships).

The revised NTP report will not be produced soon as the peer reviewers identified a range of problems which will require major changes. There may well be even newer studies reported in the interim and these may not help Connett’s case any more the ones he cited. On top of that, the NTP may well discover older studies that their biased selection process missed in their original literature search (I still hold out hope that they will this time in include Perrott (2018) which, I believe, raises important issues about the effect of confounders ignored by other studies).

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Industry-funded translation can introduce bias in selection of studies for scientific review

Image credit: Assessing and addressing bias in systematic reviews

The Fluoride Action Network (FAN), in the last decade, paid for translation of a lot of Chinese-language scientific papers linking high fluoride dietary intake to IQ deficits in children. They, of course, selected papers to fit their own ideologically-motivated bias. This is perfectly understandable for an activist group. But has this caused a bias in available English-language sources on this topic? And does this mean recent scientific reviews of this subject unintentionally suffer from selection bias?

I hadn’t considered this possibility before, but it is an issue raised in the recent US National Academies of Sciences (NAS) peer review of the US National Toxicity Program’s (NTP) review of possible neurotoxic effects of fluoride (see Another embarrassment for anti-fluoride campaigners as neurotoxic claim found not to be justified).

Use of FAN sources introduces biased study selection

The NAS peer reviewers are harshly critical of the NTP draft review. A central concern was the way the NTP evaluated the literature on the subject. The NAS peer reviewers say on page 3 of their report:

“The committee had substantive concerns regarding NTP’s evaluation of the human evidence as noted below. The strategy used for the literature search indicated that NTP used FAN as a source to identify relevant literature. The process by which FAN identified and selected studies is unclear, and that uncertainty raises the question of whether the process could have led to a biased selection of studies. Such a concern raises the need for a formal evaluation of any potential bias that might have been introduced into the literature-search process.”

OK, I am not impressed that the NTP used FAN as a source. FAN is hardly a reliable source and its “study tracker” certainly does not pick up anywhere near the full literature available (see Cherry-picking and ring-fencing the scientific literature). But, at first thought, I imagined that the FAN source simply produced a subset of anything that is picked up using a more reliable source like PubMed to do literature searches.

Injection of study bias into English-language scientific literature

But the NAS peer reviewers raise an important problem with reliance on FAN as a source and its effect on the available English-language scientific literature. On page 24 of their report they say:

“. . the process by which FAN identified and selected studies is not clear. FAN identified a number of studies published in Chinese language journals—some of which are not in PubMed or other commonly used databases—and translated them into English. That process might have led to a biased selection of studies and raises the question of whether it is possible that there are a number of other articles in the Chinese literature that FAN did not translate and about which NTP is unaware. NTP should evaluate the potential for any bias that it might have introduced into the literature search process. Possible ways of doing so could include conducting its own searches of the Chinese or other non–English-language literature and conducting subgroup analyses of study quality and results based on the resource used to identify the study (for example, PubMed vs non-PubMed articles). As an initial step in such evaluations, NTP should consider providing empirical information on the pathway by which each of the references was identified. That information would also improve understanding of the sources that NTP used for evidence integration and the conclusions drawn in the monograph.”

In a nutshell, FAN arranged and paid for translation of quite a large number of Chinese papers on this issue (fluoride intake and child IQ deficits). Naturally, they have selected papers supporting their political cause (the abolition of community water fluoridation) and ignored papers which they could not use to that end. It is therefore likely they have introduced into English-language scientific literature a biased selection of Chinese papers because FAN effectively “republished” the translated papers in the journal “Fluoride” – a well-known repository of anti-fluoride material.

Maybe I was wrong to assume anything from FAN would simply be a subset of what is available through more respectable searching sources. But, according to the peer reviewers, some of the translated papers may be picked up when FAN is used as a source of studies but not when PubMed or similar respected sources are used. A warning, though – many of the FAN-promoted translated studies have only been partly translated, maybe only the abstract is available. This is not sufficient for a proper scientific review (see Beware of scientific paper abstracts – read the full text to avoid being fooled).

I am not saying this bias introduction into the English-language scientific literature was intentional, but it is a likely end-result of their actions. Importantly, it is also a likely end-result of funding from big money sources (the “natural”/alternative health industry which funds FAN and similar anti-fluoride and anti-vaccination groups – see Big business funding of anti-science propaganda on health).

So, is this a way that big industry can inject their bias into the available scientific literature? A way to ensure that reviewers will, maybe unintentionally, convey this industry bais into their own summary of scientific findings?

Reviewers should make a critical assessment of studies

The FAN-promoted Chinese studies really do not contribute to any rational discussion of issues with CWF because they were all made in areas of endemic fluorosis. Ironically they often compare child IQ in villages where fluoride intake is high, with that in villages where the fluoride intake is low. It is the low -fluoride villages which are relevant to areas of CWF because their drinking water F concentrations are comparable.

In reality, these Chinese studies could be used to support the idea that CWF is harmless. Even if that is an inherent assumption for low fluoride intake in these studies.

So, perhaps the bias introduced to the literature by translation of the FAN-promoted studies really is of no consequence to the evaluation of CWF. However, consideration of reviews like the recent one by Grandjean (2019) indicates there is a tendency to simply extrapolate from high concentration studies to make unwarranted conclusions about CWF. In this case, the tendency is understandable as Grandjean is well known for his opposition to CWF and is often used by FAN to make press statements raising doubts about this health policy (see Special pleading by Philippe Grandjean on fluorideSome fluoride-IQ researchers seem to be taking in each other’s laundry, and Fluoridation not associated with ADHD – a myth put to rest).

This was also a problem with the draft NTP review which produced the (unwarranted) conclusion “that fluoride is presumed to be a cognitive neurodevelopmental hazard to humans.” The draft did actually mention that the conclusion “is based primarily on higher levels of fluoride exposure (i.e., >1.5 ppm in drinking water” and “effects on cognitive neurodevelopment are inconsistent, and therefore unclear”  for “studies with exposures in ranges typically found in the water distribution systems in the United States (i.e., approximately 0.03 to 1.5 ppm according to NHANES data).” But, of course, it is the unwarranted conclusion that gets promoted.

Conclusions

Reviewers need to be aware of this and other ways activist groups and big business can inject bias into the scientific literature.

This problem underlines the responsibility reviewers have of recognising all possible ways that biased selection of studies they consider can occur. It also means they should make every effort to include negative studies (not supporting the effect they may personally prefer) as well as positive studies. They also need to include all the findings (positive and negative) included in the individual studies they review.

In cases like the FAN-promoted Chinese studies, there is an obligation to at least note the possibility of bias introduced by activists and industry-funded translations. Even better, to ensure that the reviewer undertakes to independently search for all studies on the subject and arrange for translations where necessary.

Above all, reviewers should critically consider the quality of the studies they include in their reviews and not simply rely on their own confirmation bias.

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Another embarrassment for anti-fluoride campaigners as neurotoxic claim found not to be justified

Anti-fluoride campaigners have made the classic mistake of promoting claims based on a draft report. Now peer reviewers have found the claim unjustified and the report will be rewritten. But will the anti-fluoride brigade stop making the claim?

Anti-fluoride campaigners have just lost another of their propaganda claims with the release of a US National Academies of Science (NAS) peer review of the recent National Toxicity Program’s (NTP) draft monograph discussing fluoride exposure and neurotoxicity.

Ever since the release of this draft last October anti-fluoride campaigners have been making hay out of this statement on page 2 of the draft (and repeated several times in its text):

“Conclusions: NTP concludes that fluoride is presumed to be a cognitive neurodevelopmental hazard to humans.”

In general, these campaigners have presented this conclusion as a finding of the NTP, even though the draft includes this statement on every page:

“This DRAFT Monograph is distributed solely for the purpose of pre-dissemination peer review under the applicable information quality guidelines. It has not been formally disseminated by NTP. It does not represent and should not be construed to represent any NTP determination or policy.”

In a clear case of counting eggs before they hatch, the anti-fluoride campaigners now face the embarrassment of losing this claim because the NAS peer reviewers have found the conclusion is not supported by the evidence presented in the draft report. The NAS press release announcing the results of their peer review clearly says:

It “does not find that NTP has adequately supported its conclusion that “fluoride is presumed to be a cognitive neurodevelopmental hazard to humans.”

For readers wanting more detail these are the relevant documents:

Anti-fluoride activists response to the NAS peer review

The peer review has been out for only a few days and the anti-fluoride propagandists on social media have already denounced it (without reading it in most case) as only one committee’s opinion. Or they have indulged in the straw-clutching of quoting the NAS peer review’s sentence after the one that found the conclusion fo the NTP report was not supported. This says.

“The committee emphasized its finding does not mean that the NTP’s conclusion is incorrect; rather, further analysis or reanalysis is needed to support conclusions in the monograph.”

Perfectly normal for a scientific assessment and, in this case, a bit of a face-saver for the NTP (in many of its details the NAS peer review is quite scathing). And if the NTP has done a reasonable job of accessing the literature we all know that no “further analysis or reanalysis” will magically support the draft claim.

But, as an indication of the embarrassment of these people the “authoritative” comment on the peer review from Paul Connett, leader of the anti-fluoride US activist group Fluoride Action Network (FAN) almost reads like an endorsement of the peer review. Despite FAN having originally stressed the faulty NTP draft conclusion that “fluoride is presumed to be a cognitive neurodevelopmental hazard to humans” Connett does not even mention the NAS finding in his press release (see Federal report finding fluoride lowers IQ of children reviewed by National Academy of Sciences.“) Strangely he quotes: “The NAS emphasized its finding ‘… does not mean that the NTP’s conclusion is incorrect.'” without even saying what that conclusion was.

The rest of Connett’s comments amount to spin – putting a brave face on his disappointment at this major loss. His claim that “The NAS suggestions should strengthen the draft report’s conclusion that fluoride is a presumed neurotoxin in children” is fanciful given that the material reviewed by the NTP simply does not support this claim.

He is also attempting diversion with his claim “The NAS review has been misinterpreted by fluoridation defenders. The NAS did not independently review the scientific evidence but instead limited itself to comments on whether the NTP clearly and thoroughly explained their methods” The fact is very few comments have been made by “fluoridation defenders” yet – the peer review has been public for only a few days – barely enough time for busy scientists to get around to reading it. And I have not seen a single person claim that the NAS peer reviewers “independently reviewed the evidence.”

What was required of the peer review?

The peer review report makes their action and purpose very clear. They were not tasked with making an independent review of the literature but their job went a lot further than limiting themselves to “comments on whether the NTP clearly and thoroughly explained their methods”

The NTP Project Information document Peer Review of the NTP Monograph on Systematic Review of Fluoride Exposure and Neurodevelopmental and Cognitive Health Effects) provided a list of requirements for the peer reviewers who were asked to address the following questions:

  • Has the systematic review protocol been followed and modifications appropriately documented and justified?
  • Does the monograph accurately reflect the scientific literature?
  • Are the findings documented in a consistent, transparent, and credible way?
  • Are the report’s key messages and graphics clear and appropriate?  Specifically, do they reflect supporting evidence and communicate effectively?
  • Are the data and analyses handled in a competent manner?  Are statistical methods applied appropriately?
  • What other significant improvements, if any, might be made in the document?
  • Does the scientific evidence in the NTP Monograph support NTP’s hazard category conclusions for fluoride in children and adults?”

The NAS peer reviewers clearly answered the last question with an emphatic No! This is not changed by the desperate straw clutching of propagandists who quote the (inevitable and polite) qualification that a further “further analysis or reanalysis” might provide support. Nor is it changed by Connett simply refusing to acknowledge or comment on that very important finding of the peer review committee.

Other findings of the NAS peer reviewers

The NAS peer review report is quite extensive (it’s 48 pages long) and covers several other important issues besides its rejection of the main conclusion. Issues related to how good the original protocol was and how closely it was followed, bias resulting from incomplete consideration of all the findings (negative as well as positive) and selection in the literature considered, issues related to statistical analysis and presentation, and problems with accounting for the range of different fluoride exposure measures and outcome parameters.

I might return to some of these issues later as I think they are relevant to other reviews in this area – especially the recent review of Grandjean (2019) – Developmental fluoride neurotoxicity: an updated review. This has similar faults – and some extra faults of its own.

But it is clear that in it’s current form the draft NTP report is not credible. Its conclusion is flawed and there are a number of other problems. It will have to be extensively rewritten to take the peer reviewers comments into account. I look forward to the new, and hopefully much better, version.

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Beware of scientific paper abstracts – read the full text to avoid being fooled

Inaccuracies are very common in scientific paper abstracts. Image credit: Science in the Abstract: Don’t Judge a Study by its Cover

I have come to accept anti-fluoride campaigners will never stop cherry-picking research and findings to support their claims but it annoys me when scientists themselves cherry-pick their findings to support a preconceived belief. I guess it’s only human, but it does reinforce my belief that one should never rely on abstracts to understand a paper – one should read the full text. Abstracts are the very place authors will cherry-pick their findings to promote a preferred theory.

Hilda Bastian wrote “Ivan Oransky from Retraction Watch says it’s “journalistic malpractice” to report on a study after only reading an abstract or press release” (see Science in the Abstract: Don’t Judge a Study by its Cover): 

“To be fair, even though it’s a worry, every inaccuracy isn’t critical. But the spin is serious. It’s not just about language that exaggerates or massages results. It’s also about choosing the most exciting results, even when that’s misleading.

Spin in press releases and media coverage often reflects the spin in abstracts. And until more research is open access, that will be all that most people can get to read. In 17 studies of inconsistencies of all kinds in abstracts of biomedical medical research papers, the rate of major problems ranged from 5% to 45% (median 19%)!”

Here is a rather blatant example in recent findings on possible effects of fluoridation for formula-fed babies. The research findings were reported in two places. Firstly a conference paper:

Till, C., Green, R., Flora, R., Hornung, R., Martinez-Mier, E., Blazer, BFarmus, L., … Lanphear, B. (2019). Fluoride Exposure from Infant Formula and Child IQ in a Canadian Birth Cohort. Environmental Epidemiology, 3.

And secondly, a journal paper which provides a full text and the findings in full:

Till, C., Green, R., Flora, D., Hornung, R., Martinez-mier, E. A., Blazer, M., … Lanphear, B. (2020). Fluoride exposure from infant formula and child IQ in a Canadian birth cohort. Environment International, 134(September 2019), 105315.

Let’s look at the actual findings and then consider how they were presented in the abstracts of these two reports.

The findings these reports rely on

This is the data taken from Till et al (2020) illustrating the differences in IQ measures for children (3 – 4 years old) living in fluoridated and nonfluoridated areas. Full-scale IQ (FSIQ) is the usual IQ measures and Verbal IQ (VIQ) and Performance IQ (PIQ) are indices resulting from subtests.

The only statistically significant differences are for VIQ (greater for children breastfed as babies living in fluoridated areas) and PIQ (lower for children formula fed as babies living in fluoridated areas)

The authors don’t comment on those results in either report but they also considered possible relationships between measures of fluoride exposure (water-F concentration and an estimate of F intake from formula). Here are the findings for these.

As we can see the relationship with FSIQ and VIQ are not statistically significant, but the ones with PIQ are. It’s a bit strange – and I do not have the understanding of IQ measurements to interpret the fact that while there were no relationships with the normal IQ measure, there were with the PIQ subtest. However, here is a statement from the reference used by Till et al (2020) in the Methods section (Wechsler, D., 2002. Wechsler Preschool and Primary Scale of Intelligence – Third Edition: Canadian. Pearson Clinical Assessment, Toronto, ON, Canada):

“Subtest and profile interpretation methods are not consistent with Standards for Educational and Psychological Testing (AERA, APA, NCME, 1999) and should not be used in clinical decision-making until psychometric support for them is provided. In the words of Weiner (1989), the ethical psychologist will “(a) know what their tests can do and (b) act accordingly” (p. 829).”

The conference abstract

Here is the relevant section from the conference abstract for Till et al (2019). Only FSIQ is discussed and there is no mention of VIQ or PIQ:

“An increase of 0.5 mg/L fluoride concentration (the difference between fluoridated and non-fluoridated region) corresponded to a drop of 4.4 FSIQ points (95% CI: -8.34, -0.46, p=.03) in the formula-fed group. In contrast, this relationship was not significant in the breastfed group (B=-1.34, 95% CI: -5.04, 2.38, p=.48). Controlling for prenatal fluoride exposure weakened the association between water fluoride concentration and FSIQ in the formula-fed group (B=-3.88, 95% CI = -8.12, 0.37, p=.07).
Conclusions: The results, which indicate that fluoride concentration in drinking water was associated with lower FSIQ in children who were formula-fed, underscore the need to reduce the use of fluoridated water to reconstitute formula during infancy.”

So concentration on FSIQ – and special pleading to make the relationship important (we “need to reduce the use of fluoridated water”) despite the fact it is not statistically significant.

OK, I acknowledge p<0.05 is arbitrary and we should not have hangups on that but one should also consider the scatter of the data and how that affects the strength (or in this case weakness) of the relationship. Here is the actual data as presented in Till et al (2020) – that, and the large confidence interval ( -8.12 to 0.37), warn us that any relationship, significant or not, is extremely weak.

[I discussed this in my article Anti-fluoride propagandists appear not to read the articles they promote and mentioned that although I was able to digitally extract about 90% of the data from this figure my statistical analysis was quite different to that of Till et al (2020).This is probably an inevitable result of the large scatter in data points and the very weak relationship – any change in the position of a few data points could have a big effect on the regression result.]

The paper abstract

Here is the relevant section from the full-text paper abstract for Till et al (2020). Now, there is no mention of FSIQ – only PIQ is mentioned:

“An increase of 0.5 mg/L in water fluoride concentration (approximately equaling the difference between fluoridated and non-fluoridated regions) corresponded to a 9.3- and 6.2-point decrement in Performance IQ among formula-fed (95% CI: −13.77, −4.76) and breast-fed children (95% CI: −10.45, −1.94). The association between water fluoride concentration and Performance IQ remained significant after controlling for fetal fluoride exposure among formula-fed (B=−7.93, 95% CI: −12.84, −3.01) and breastfed children (B=−6.30, 95% CI: −10.92, −1.68). A 0.5 mg increase in fluoride intake from infant formula corresponded to an 8.8-point decrement in Performance IQ (95% CI: −14.18, −3.34) and this association remained significant after controlling for fetal fluoride exposure (B=−7.62, 95% CI: −13.64, −1.60).

Conclusions: Exposure to increasing levels of fluoride in tap water was associated with diminished non-verbal intellectual abilities; the effect was more pronounced among formula-fed children.”

Changing the goalposts – but activists don’t care

Before the full-text journal paper was available activists promoted this work – completely ignoring the lack of statistical significance in the relationship – or at least relying completely on the significant relationship when unadjusted for other important factors.

I have said that activists usually don’t bother reading actual papers, sometimes not even abstracts. But we still have activists promoting this research and citing the relationships for PIQ – but still calling it IQ!

For example:


ChristineM@Christi45657364

All the more reason not to ADD F to tap water. Today the 63rd human study linking F with reduced IQ was published. Fluoride exposure from infant formula and child IQ in a Canadian birth cohort: https://www.sciencedirect.com/science/article/pii/S0160412019326145 

Fluoride exposure from infant formula and child IQ in a Canadian birth cohort

Infant consumption of formula reconstituted with fluoridated water can lead to excessive fluoride intake. We examined the association between fluoride…


And


ChristineM@Christi45657364

Example of recent Canadian studies: NIH-funded study: Fluoride exposure from infant formula and child IQ in a Canadian birth cohort https://ncbi.nlm.nih.gov/pubmed/31743803  found children fed infant formula mixed with fluoridated water (vs. unfluoridated) had significantly lower IQ’s.


So, this woman is heavily promoting a paper with misinformation as the story is not about IQ or FSIQ at all. The only significant relationships are with a subtest which we are warned against using anyway. (Mind you, this woman seems to alternate her prolific anti-fluoride tweets with prolific anti-vaccination tasks so we can see she is hardly worried about the truth of her claims).

Reader beware

I have always urged people not to rely on social media, or even mainstrem media, reports about new research but to actually read the scientific reports themselves. But this example makes clear that it is not enough to just read abstracts – a very easy lazy habit to fall back on as there is more work to obtaining the full text of papers.

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Fluoridation and sex steroid hormones – or the mouse that roared

All the recent research anti-fluoride campaigners promote as “evidence” of harm from community water fluoridation amount to cherry-picking a very few statistically significant results from a large number of non-significant results. The whole exercise is a bit like the “Mouse that Roared.” Credit: The Mouse that Roared – TMTR Intro animation

Another one of those papers with weak or vague relationships with fluoride intake has just been released and is already being promoted by anti-fluoride activists. These activists probably don’t even read these papers but because they confirm their biases they will promote them anyway.

The evidence in this paper is very poor. A large number of sex steroid hormone measures were investigated. None were significantly related to fluoride in water and very few related to blood plasma F levels.

So this new paper is no better than those I reviewed in What are the recent fluoride-IQ studies really saying about community water fluoridation? (Incidentally, I have updated that article to include the recent paper I had discussed in Sleep disorders and fluoride: dredging data to confirm a bias and provided all the results from that study).

The new paper is:

Bai, R., Huang, Y., Wang, F., & Guo, J. (2020). Associations of fluoride exposure with sex steroid hormones among U.S. children and adolescents, NHANES 2013–2016. Environmental Pollution, 114003.

It uses data from a US database so is relevant to community water fluoridation (unlike most studies promoted by anti-fluoride campaigners which are from areas of endemic fluorosis). Basically, it looks for significant relationships of drinking water fluoride or blood plasma fluoride with three sex steroid hormones (testosterone, Estradiol and sex hormone-binding globulin -SHBG) in male children, male adolescents, female children and female adolescents. So a lot of measures and relationships from which to find significant ones.

The results they found are shown in the three figures below -which are figures 1, 2 and 3 from the paper. The methodology used appears quite confused. Instead of simply reporting regression results for the correlation of the hormone levels with water and plasma F they appear to have divided the fluoride data into tertiles. That is the set of one third lowest values, the set of middle third of the values and the set of one third highest values.

They then report differences between the mean hormone levels in the 2nd and first tertile and differences between the mean hormone levels in the third and first tertile. The p-values in the second to the last column indicates the statistical significance of these differences.

The last column reports a p-value for the “trend” – but this appears to be simply a correlation of the geometric mean hormone level against the median water-F or blood plasma-F for each tertile. That is only 3 sample pairs for each set considered. It is a mystery to me that they didn’t simply report linear regressions of all the values in the sample sets. Perhaps this is the only way they could find anything significant.

It would have been more helpful to present all the data graphically so readers could see how scattered it is. (The confidence intervals shown in the graphics below indicate a large amount of scatter).

There are very few statistically significant results – those shown in red. These were for male adolescents and the total sample where there was a decline in levels of testosterone and estradiol with increaser of blood plasma-F. The result foir the total sample probably reflects the male adolescent result as there was no significant difference between either the second or third tertile and the reference first tertile, or any significant decline, for any of the other groups (male children, female children and female adolescents). There were no significant effects with water-F for these hormones with any of the groups.

Ther only significant effects seen with  SHBG  was a decrease in the SHBG level for male adolescents when comparing the third tertile of water-F with the first tertile. And for female children a decrease in SHBG levels when comparing the values for the second tertile of blood plasma-F against the first tertile.

Conclusion

So all this is a bit like the mouse that roared. Despite claims in the conclusion that the public health applications of their finding “are substantial” I do not think there is anything here for public health experts to get concerned about.

My conclusions parallel those expressed for the cognitive studies in What are the recent fluoride-IQ studies really saying about community water fluoridation?.

This is the sort of picture one might expect from exploratory studies using several hormones for different population groups and several measures of fluoride exposure. While these results may be useful in suggesting possible hypotheses to check in future better-designed experiments they are not sufficiently coherent to inform social health policy.

My conclusions about the recent fluoride studies for levels relevant to community water fluoridation applies equally to this study:

“These recent studies do not provide sufficient evidence for revision of community water fluoridation policies because of possible effects on cognitive abilities. Anti-fluoride activists have only been able to use these studies in their scaremongering propaganda by cherry-picking results and ignoring the weakness of the relationships they cite.”

Similar articles

What are the recent fluoride-IQ studies really saying about community water fluoridation?

Scaremongering graphic currently being promoted by Declan Waugh who is well known for misrepresenting the fluoride science

This graphic is typical of current anti-fluoride propaganda. It is scare-mongering, in that it is aimed at undermining community water fluoridation (CWF) which is accepted by health and scientific authorities as safe and effective. It relies on citations of recent research to give an impression of scientific credibility – but it misrepresents that research.

In fact, this research has produced confusing and contradictory results based on very weak relationships. Instead of the cherry-picking commonly indulged in by anti-vaccination and anti-fluoridation groups like this, all the findings in these studies must be considered. In this article, I have attempted to graphically present all these findings in one place. This makes clear how weak the evidence these activist groups rely on is and why it does not provide a basis for reviewing the current acceptance of CWF.

I have given below all the reported findings from the recent research (including the citations given by Declan Waugh in the above graphic). There is a lot here (I have not cherry-picked as the anti-fluoride activists do) so I present the findings graphically to provide a complete overview without the boring job of trying to understand  detailed text. My apologies for the length of this article.

NOTE: I recommend readers refer to the cited papers for more details on methodology and definitions of the cognitive measures and F-exposure measures.

Does fluoridation influence IQ?

The answer provided by these modern studies is clearly no. Remember, these studies use data from areas where CWF is used or where drinking water concentrations are similar. They are quite different from the studies (previously relied on by anti-fluoridation activists) from areas of endemic fluorosis where fluoride intake is much higher and where many health problems result.

All the comparisons from fluoridated and unfluoridated areas in these studies are presented in Figure 1 below. The bars represent the standard deviations for the data sets and the data points are the means. A * indicates differences are statistically significant.

Figure 1:  Comparison of IQ results in fluoridated and non0-fluoridated areas

The only statistically significant differences are for verbal IQ (VIQ) of 3-4 year-olds breastfed as babies (where the VIQ of children in fluoridated areas is higher) and for performance IQ (PIQ) of the same group (where the PIQ of children in fluoridated areas is lower). Till et al (2020) had to dig deep, use multiple measures of the cognitive score and subdivide the children into groups, to find an occasional difference. And these differences are contradictory.

I discussed the Till et al (2020) study which reported these occasional differences in Anti-fluoride propagandists appear not to read the articles they promote.

What about the relationships between IQ and measures of F intake?

Anti-fluoride propagandists ignore the data presented in Figure 1 above (and reported in the papers involved) and instead rely on cherry-picked relationships between measures of cognitive ability and various measures of fluoride exposure. Yes, some of these relationships, but only a small proportion, are statistically significant. But, importantly, none of these explain more than a few percents of the variation of the cognitive measure used.

Figure 2 below displays all the results from all the recent studies where linear regressions were used. The coefficient represents the size of the effect (eg., the change in IQ for every 1 mg/L increase of F exposure measure like drinking water F or maternal urinary F) and the bars represent the 95% confidence levels. The statistically significant (p<0.05) relationships are represented by red points while the green data points represent nonsignificant results.

Figure 2: Relationships of cognitive measures with exposure to fluoride obtained by linear regression analyses

Footnote: UF – concurrent urinary fluoride of the child. UFsg – UF adjusted using the specific gravity of urine. MUF – maternal prenatal urinary fluoride. MUFcr MUF – adjusted using urinary creatinine concentration. MUFsg – MUF adjusted using urine specific gravity. FSIQ – Full-Scale IQ. VIQ – Verbal IQ. PIQ – performance IQ. MDI – Mental development index.

Figure 3 below displays the results obtained by Barberio et al (2017) using logical regression of learning disabilities in children aged 3-12 years on urinary fluoride (UF), specific gravity adjusted urinary fluoride (UFsg), and creatinine adjusted urinary fluoride (UFcr). The data used was from two cycles of the Canadian Health Measures Survey (CHMS).

Findings for logical regression of ADHD and ADD on urinary fluoride are also included.

Figure 3: Relationships of cognitive measures with exposure to fluoride obtained by logical regression analyses

There are a lot of reported relationships in these two figures but only a few are statistically significant. Even these are contradictory – Thomas (2014) and Santa-Marina (2019) found positive coefficients while Bashash et al (2017), Thomas (2018), Green et al (2019) and Till et al (2020) reported some negative relationships. Barberio et al (2017) found a positive relationship for the data from combined CHMS cycles but this disappeared when UFsg or UFcr was used. Most of the reported relationships are not statistically significant.

Moving from nonsignificant to significant by adjusting urinary-F figures

This is illustrated by the evolution of the way the results are presented for the Thomas (2014) study which is related to the Bashash et al (2017) study. In this thesis and early conference reports (Thomas et al 2013 & Thomas et al 2014), She did not find any statistically significant relationships of child IQ with maternal urinary F (MUF) or maternal blood plasma F. But she did report a statistically significant relationship with MUFcr in her last conference paper (Thomas et al 2018).

So what happened?

There appears to be a change in the actual mother-child pairs used as indicated by the numbers and this sort of data selection can easily push a nonsignificant relationship into significance – especially when the relationship is so weak (see A conference paper on the maternal prenatal urinary fluoride/child IQ study has problems).

The other factor is that in the 2018 conference paper she has adjusted the MUF figures using creatinine concentration. Use of individual urinary fluoride measures, especially spot samples rather than a 24-hr collection, is a problem and is not a good measure of F exposure. Adjustment of urinary F using specific gravity or creatinine concentration is often used to improve the measure but this is problematic because creatinine concentration is influenced by a range of other factors.  The adjusted MUF figures may actually be acting as a proxy for one of these other factors. This is why Barr et al (2005) recommended that:

“ For multiple regression analysis of population groups, we recommend that the analyte concentration (unadjusted for creatinine) should be included in the analysis with urinary creatinine added as a separate independent variable. This approach allows the urinary analyte concentration to be appropriately adjusted for urinary creatinine and the statistical significance of other variables in the model to be independent of effects of creatinine concentration.”

This is not done by any of the authors of these recent papers where urinary fluoride was used.

Thomas (2014) also reported a positive relationship of concurrent child urinary F (UF) with a cognitive measure, but not for girls. This seems to have been ignored in later reports – and by Bashash et al (2017) which used the same data but only reported the non-significant result for all children.

Till et al (2020) found that only relationships with PIQ were statistically significant. It is not clear why this happened considering no significant relationships were found for FSIQ or VIQ. It’s interesting that Till et al (2019) initially did not report the PIQ results and instead relied on a significant relationship of FSIQ with water F in children formula-fed as babies. Maybe the PIQ measurement is considered unreliable in practice. This finding was also heavily promoted by ant-fluoride campaigners – despite the fact that adjustment for other factors made this relationship nonsignificant (see Anti-fluoride propagandists appear not to read the articles they promote).

Most anti-fluoride campaigners have stuck with the initial FSIQ relationship – although a few who may have read the paper are now cherry-picking the PIQ relationships and ignoring the others.

What about fluoride and ADHD?

Three of these recent studies used linear regression when considering ADHD – but those of Malin & Till (2015) (claimed to be the first study to suggest an effect of fluoridation on ADHD) and Perrott (2018) are important. Not because one of the studies is mine – but because they illustrate a basic problem with correlation studies.

Even when multiple regression is used to adjust for covariants or other possible risk-modifying factors the investigation may miss an important risk-modifying factor. Not only does correlation not prove causation – the “significant” relationships themselves may be false when important risk-modifying factors are not included in the multiple regressions.

This happened with the Malin & Till (2015) study which reported statistically significant relationships of the extent of fluoridation in US states with ADHD prevalence. However, when the mean state elevation was included in the multiple regression of exactly the same data by Perrott (2018) the relationship with fluoridation extent disappeared (this had a p-value of 0.269 whereas those for Malin & Till 2015 were <o.o5). See Figure 4 below.

Figure 4: The effect of including other important risk-modifying factors on reported significant relationships

Figure 5 below shows the data reported by Bashash et al (2018) for the linear regression of a range of ADHD symptoms against urinary fluoride (UFcr).

Figure 5: Relationships of ADHD symptoms with exposure to fluoride obtained by linear regression analyses

The relationships were statistically significant for only four of the ten symptoms considered. Those relationships were very weak, explaining only a few per cent of the variance in ADHD prevalence (see Fluoridation and ADHD: A new round of statistical straw clutching).

The logistical regression results reported by Riddell et al (2019) for ADHD diagnosis and SDQ subscale score Urinary fluoride (UFcr) are given in Figure 6 below.

Figure 6: Relationships of ADHD diagnoses  with exposure to fluoride obtained by logistical regression analyses

I discussed Riddell et al (2019) in my article ADHD and fluoride – wishful thinking supported by statistical manipulation?

This is another case where authors found unpromising results (no significant relationship for UFsg for example) and searched for other measures. It is also interesting that the significant relationships for water F and CWF status disappeared for younger children when age separation was used. The large confidence intervals in most cases indicate a large scatter in the data and very weak relationships.

I should also mention here the nonsignificant relationships reported by Barberio et al (2017) for ADHD and ADD (see Figure 3 above). These just underline how significant relationships are not common in these recent studies when looked at overall.

Update: Fluoride and sleep disturbances

Strictly, sleep disturbances don’t come under the classification of cognitive effects but a recent paper on fluoride and sleep disturbances is being promoted by anti-fluoride campaigners and should, therefore, be included here. For the sake of completeness.

I discussed the paper, Malin et al (2019), in my article Sleep disorders and fluoride: dredging data to confirm a bias. All the findings reported in that paper, and the supplementary files, are presented in Figure 7 below.

The authors report relationships of a range of sleep disorders against two measures of fluoride exposure – blood plasma-F and tap water-F. None of the relationships with blood plasma were significant (most had a p-value of 1.0). I discussed these in Sleep disorders and fluoride: dredging data to confirm a bias. and made the point that that bedtime and waketime were likely to be related to residence and the tap water F was simply acting as a proxy for regional location.

But again we see the use of a large number of measures for a “disorder’ and very few statistically significant relationships which are probably better explained by other factors than fluoride.

Conclusion

Considering all the findings together of the recent studies relevant to community water fluoridation and cognitive factors shows the results are weak, conflicting, and contradictory. This is probably not surprising considering the nature of the data (the studies were basically exploratory using existing databases – not designed experiments). Although adjustments were made for other possibly important factors this does not mean those really important ones (like the relationship of ADHD prevalence to elevation) were included. All the statistically significant relationships found were very weak – explaining a small proportion of the variance in the cognitive measure.

This is the sort of picture one might expect from exploratory studies using a large number of cognitive factors and measure of fluoride exposure. While these results may be useful in suggesting possible hypotheses to check in future better-designed experiments they are not sufficiently coherent to inform social health policy.

These recent studies do not provide sufficient evidence for revision of community water fluoridation policies because of possible effects on cognitive abilities. Anti-fluoride activists have only been able to use these studies in their scaremongering propaganda by cherry-picking results and ignoring the weakness of the relationships they cite.

References

Aggeborn, L., & Öhman, M. (2016). The Effects of Fluoride In The Drinking Water.

Barberio, A. M., Quiñonez, C., Hosein, F. S., & McLaren, L. (2017). Fluoride exposure and reported learning disability diagnosis among Canadian children: Implications for community water fluoridation. Can J Public Health, 108(3), 229.

Barr, D. B., Wilder, L. C., Caudill, S. P., Gonzalez, A. J., Needham, L. L., & Pirkle, J. L. (2005). Urinary creatinine concentrations in the U.S. population: Implications for urinary biologic monitoring measurements. Environmental Health Perspectives, 113(2), 192–200.

Bashash, M., Thomas, D., Hu, H., Martinez-mier, E. A., Sanchez, B. N., Basu, N., … Hernández-avila, M. (2017). Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6 – 12 Years of Age in Mexico. Enviromental Health Perspectives, 1, 1–12.

Bashash, M., Marchand, M., Hu, H., Till, C., Martinez-Mier, E. A., Sanchez, B. N., … Téllez-Rojo, M. M. (2018). Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6–12 years of age in Mexico City. Environment International, 121(August), 658–666.

Broadbent, J. M., Thomson, W. M., Ramrakha, S., Moffitt, T. E., Zeng, J., Page, L. A. F., & Poulton, R. (2015). Community water fluoridation and intelligence: Prospective study in New Zealand. American Journal of Public Health, 105(1), 72–76.

Green, R., Lanphear, B., Hornung, R., Flora, D., Martinez-Mier, E. A., Neufeld, R., … Till, C. (2019). Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada. JAMA Pediatrics, 1–9.

Malin, A. J., & Till, C. (2015). Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association. Environmental Health, 14(1), 17.

Malin, A. J., Bose, S., Busgang, S. A., Gennings, C., Thorpy, M., Wright, R. O., … Arora, M. (2019). Fluoride exposure and sleep patterns among older adolescents in the United States : a cross-sectional study of NHANES 2015 – 2016. Environmental Health, 1–9. Retrieved from https://link.springer.com/article/10.1186/s12940-019-0546-7

Perrott, K. W. (2018). Fluoridation and attention deficit hyperactivity disorder a critique of Malin and Till (2015). British Dental Journal, 223(11), 819–822.

Riddell, J. K., Malin, A., Flora, D., McCague, H., & Till, C. (2019). Association of water fluoride and urinary fluoride concentrations with Attention Deficit Hyperactivity Disorder in Canadian Youth. Submitted to Environment International, 133(May), 105190.

Santa-Marina, L., Jimenez-Zabala, A., Molinuevo, A., Lopez-Espinosa, M., Villanueva, C., Riano, I., … Ibarluzea, J. (2019). Fluorinated water consumption in pregnancy and neuropsychological development of children at 14 months and 4 years of age. Environmental Epidemiology, 3.

Thomas, D. B. (2014). Fluoride exposure during pregnancy and its effects on childhood neurobehavior: a study among mother-child pairs from Mexico City, Mexico. University of Michigan.

Thomas, D., Hu, H., Basu, N., Sanchez, B., Bellinger, D., Schnaas, L., … Tellez-Rojo, M. M. (2013). A prospective study of prenatal exposure to fluoride and neurobehavior : preliminary analyses. Environmental Health Perspectives.

Thomas, D., Hu, H., Basu, N., Martinez-Mier, E. A., Sanchez, B., Bellinger, D., … Tellez-Rojo, M. M. (2014). Urinary Fluoride in Pregnant Women and Prenatal Fluoride Exposure and Mental Development Index ( MDI ) in 1-3 Year Old Infants from Mexico City, Mexico. Environmental Health Perspectives, 1(Icc), 2–3.

Thomas, D., Sanchez, B., Peterson, K., Basu, N., Angeles Martinez-Mier, E., Mercado-Garcia, A., … Tellez-Rojo, M. M. (2018). OP V – 2 Prenatal fluoride exposure and neurobehavior among children 1–3 years of age in Mexico. Environmental Contaminants and Children’s Health, 75(Suppl 1), A10.1-A10.

Till, C., Green, R., Flora, R., Hornung, R., Martinez-Mier, E., Blazer, BFarmus, L., … Lanphear, B. (2019). Fluoride Exposure from Infant Formula and Child IQ in a Canadian Birth Cohort. Environmental Epidemiology, 3.

Till, C., Green, R., Flora, D., Hornung, R., Martinez-mier, E. A., Blazer, M., … Lanphear, B. (2020). Fluoride exposure from infant formula and child IQ in a Canadian birth cohort. Environment International, 134 (September 2019), 105315.

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Fluoridation science and political advocacy – who is fooling who?

misinformation

It is a false balance to equate the advocacy of scientific and medical experts concerned with truth and child health to the advocacy of ideologically-motivated anti-fluoride and anti-vaccination activists known for their misrepresentation of science. Credit: World Congress for freedom of scientific research

I thank Dr Ghali for taking up my offer of a right of reply to my article Scientific integrity requires critical investigation – not blind acceptanceThis sort of discussion is important and I am pleased he took the time to read my article.

Unfortunately, he did not respond to my point about the need to critically examine research findings and claims. Or my point that he seemed to be attempting to “sweep aside” critical reviews which are inherently part of the scientific process. His characterisation of the letter sent by 30 academic and health experts to the US National Institute of Environmental Health Science (NIEHS) about the  Green et al (2019) study (see Experts complain to funding body about quality of fluoride-IQ research) was unjust and simply avoided the necessary discussion.

However, in his reply, he raises a new issue that is worth discussion. That of how scientists should respond to “advocacy positions.”

Equating political and scientific/health advocacy

He says:

“. . we tried in our presentations to shed some light on the controversy, and to show how advocacy positions have focused on attacking both the evidence on benefits of fluoride (e.g., the multi-pronged attacks on Lindsay McLaren’s study on CWF), and the more recent evidence on potential negative cognitive effects in developing brains.”

This characterisation falls into the trap of equating the advocacy of anti-fluoride activists, organisations like the Fluoride Action Network (FAN) and Fluoride Free NZ (FFNZ), who are well known for distorting and misrepresenting the science, with scientific and medical experts who are attempting to present a good faith expert scientific interpretation and critique of current research.

I believe this is a dangerous position because it comes across to policymakers as saying the scientists disagree with each other, that there is not a majority consensus,  and equates the standard of science presented by both sides. This impression is, of course, very much favoured by political activists because it is an easy way of discrediting scientific information, of avoiding the need to properly and objectively consider the information.

I saw this myself when the fluoridation issue was being considered by the local Hamilton City Council in 2013. Councillors were clearly not up to the job of considering the science (and why should they be) so reacted to any attempt to present scientific details by arguing that “scientists disagree with each other,” that there are “two sides to the science.” In the end, they even based their decision on things like the number of submissions as the deciding factor instead of on the science.

Incidentally, the voters in Hamilton did not let the council get away with such a sloppy disregard for the science and of their own previously expressed majority support for fluoridation. A new referendum was demanded and the result confirmed that of the previous referendum showing 70% support for community water fluoridation.

I cannot understand why Dr Ghali promotes this understanding – even to the extent of appearing to favour those who misrepresent the science above those who are attempting a good scientific critique. For example, he describes the anti-fluoride activist attacks on the science merely as “strong” and “rooted in positional anti-fluoride advocacy,” while he refers to “the unusually vigorous attacks on the fluoride cognition studies” and argues these are “seemingly rooted in the challenging findings of those studies. “

Interpreting normal scientific critique as an “attack”

Dr Ghali specifically mentions the fluoridation cessations study of McLaren et al (2016) as being strongly attacked. Part of that “strong attack” was a published critique of FAN members – Neurath et al (2017) – the sort of critique fully acceptable and expected in the scientific community. McLaren et al., (2017) in turn responded to that critique. Again a normal and necessary process in science. In fact, the opening sentence in this response was:

“Thank you for the opportunity to respond. We are pleased to see thoughtful debate in the peer‐reviewed literature and agree that careful consideration of study limitations can stimulate improvement.”

That is how such critiques should be dealt with – welcomed and responded to. That should have been the way to respond to the critique of the 30 scientific and medical experts who responded to the Green at al (2019) study in their letter (see Experts complain to funding body about quality of fluoride-IQ research).

Yet  Dr Ghali’s response to that letter was:

  • He described it as “The notion that you can just talk away 10 years of research.”
  • He leapt to an emotional defence of the authors of the Green study, saying: “I respect the doers of the research and the deliverers of the evidence and don’t think they should be shot for tough messages.”
  • He uses phrases like  “once published it can’t be unpublished” and refers to this critique as “sweeping aside because one disagrees.”
  • And in his response here (see Scientific integrity & fluoridation – Dr Ghali responds) he reverts to this emotional rejection of the normal scientific critique saying  he could not “pretend that the new studies do not even exist or that they are fatally flawed with irrelevant results.”

Ignoring the real political attacks on the science

But where is his emotional response to the way anti-fluoride activists have resorted to disgusting personal attacks on Lindsay McLaren for her work? That is surely unacceptable in any scientific discussion

An example of the personal attacks on Lindsay McLaren for her fluoridation cessation work. Source: Why the anti-fluoride haters are attacking a Calgary academic, calling her a ‘fraud’

Or to the way that these activists have misrepresented and distorted the findings of the Green et al (2019) study?

Image used in advertising campaigns of FAN and FFNZ which completely misrepresents the scientific findings.

This sort of scaremongering advertising has appeared quite widely in newspapers and public billboards in New Zealand and caused a lot of concern among health professionals and their patients.

Who is advocating for what?

The political position of the anti-fluoride activists is clear – they advocate to end fluoridation or prevent it where it is being considered. This advocacy comes from ideological positions as can be seen with their alliance with anti-vaccination activists in Health Liberty and their funding by the “natural”/alternative health industry (eg., Mercola.com and the NZ Health Trust and see Big business funding of anti-science propaganda on health).

But it is simply wrong to put the advocacy of scientific and medical experts as operating at the same level. This is made clear in the letter from the 30 experts (that Dr Ghali dislikes) which says in its summary:

“The aim of science is to gain a better understanding of our natural world and to build a shared knowledge base for the benefit of all. Every scientist is interested in the truth. If fluoride at common levels of maternal exposure does lead to lower IQ scores, we would certainly want to know. This is why transparency related to the Green article is crucial.”

To be clear – the scientific and medical experts are advocating for good science and the health of the public, especially children. That is what drives their legitimate demand for transparency in the science.

So, I think Dr Ghali is disingenuous to present a false balance between the arguments of scientific and medical experts and the ideologically-driven anti-fluoride activists. He is wrong to treat scientific and medical experts as just another “advocacy group” like FAN. And he is especially wrong to use this false balance to ignore or discredit normal scientific critique which is so essential to good science.

Dr Ghali falsely equates the advocacy of anti-fluoride activists as illustrated by this scaremongering billboard with the advocacy of medical and scientific experts who are concerned about child health and want to know the truth.

Dr Ghali’s characterisation of the new fluoride cognitive studies

I also find the way Dr Ghali’s presentation of both the recent cognitive studies and the expert discussion of them disturbing. he says:

“The new cognition studies (led, interestingly, by two Canadian public health research teams) and the ensuing NTP draft report from the US are now such that it would have been absurd for us to pretend that the new studies do not even exist or that they are fatally flawed with irrelevant results.”

Who the hell is pretending that these studies do not exist? How is a rational, good-faith scientific critique of these studies pretending they “do not even exist?”

As for the question of the possibility these studies “are fatally flawed with irrelevant results,” how can anyone ever decide that question if the scientific critique of the studies is not permitted – or thoughtlessly, even emotively, disregarded?

Even Dr Ghali admits these studies have limitations (although I am unaware of any discussion by him of those limitations). Surely an honest scientific discussion of the is work requires a discussion of these limitations – and that is exactly what the letter from the 30 experts did. It listed ten important limitations – yet Dr Ghali wishes to dismiss the letter. He has certainly shown no interest in considering the specific limitations of the study.

These limitations may well mean the results are irrelevant to the question of community water fluoridation. I have argued that in several articles. I think the conflicting and contradictory results from the different papers and different databases (ELEMENT in Mexico City, MIREC in Canada, INMA in Spain, and NHANES in the USA) do suggest the quality of the results mean they should not directly influence health policy. I have also raised the issue of naive presentation of statistical analysis, reliance only on p-values with no discussion of the small size of the effects as indicated by the inability of the relationships to explain more than a few per cent of the variance in cognitive factors. There is also the problem of using a large number of factors with the inevitable p-hacking – a problem which, I believe, is actually quite widespread in science and needs to be countered.

Dr Ghali appears to argue that these new studies are not fatally flawed despite acknowledging they have “limitations” and that the results of the studies are relevant to CWF. But how can he come to that conclusion without making an objective analysis of the study’s methodology, considering the weak nature of the relationships reported? He is certainly not performing a proper scientific review by simply taking the authors’ claims as fact.

Dr Ghali appears to argue that these new cognition studies be given a free pass – that they not be subjected to the normal scientific process of proper peer-review and critical analysis. He appears to be turning a blind eye to the way these studies have been misrepresented and their finding distorted in scaremongering advertising by anti-fluoride organisations. Does he not realise his attitude plays directly into the hands of the ideologically motivated anti-fluoride and anti-vaccination activists? Can he not draw an appropriate conclusion from the fact that his arguments are being promoted by ideologically motivated activists known for their misrepresentation and distortion of science?

Conclusions

If readers think I have been too harsh in my discussion here they should consider that Dr Ghali’s response did not in any way deal with the points I raised about the need for ongoing scientific discussion. In fact, he went further suggesting that I, or others,  may be pretending “that the new studies do not even exist or that they are fatally flawed with irrelevant results.”

That is patently not true as I have critiqued and discussed these studies in a number of articles here – there is no pretence in my position or the position of others who have participated in a principled discussion of the limitations and faults in this work.

I also did not appreciate Dr Ghali’s suggestion that we could “have a chat some time.” In my experience invitations to private chats as a substitute for participation in a good-faith open scientific discussion are simply a bureaucratic attempt to close down that discussion – or to silence a participant.

Another important factor is that while Dr Ghali attempts to discredit those who honestly critique these new cognitive studies from a scientific perspective he is apparently unwilling to criticise anti-fluoride activists who misrepresent the work and use that misrepresentation in scaremongering claims and advertising campaigns. I specifically asked Dr Ghali if he could point me to any video content where he was critical of the anti-fluoride campaigners – so that I could use it in this post as a balance to the video in my article Scientific integrity requires critical investigation – not blind acceptance where he strongly criticises those participating in a scientific critique. He did not respond which make me think he is unable to find anything where he has subjected anti-fluoride activists to the same emotive attack as he leveled at those critiquing the Green et al (2019) paper.

It is sad to see such partisanship in one who has had the responsibility of reviewing the research in this area.

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Scientific integrity & fluoridation – Dr Ghali responds

Video produced by Calgarians for Kid’s Health which is campaigning for the return of Community water fluoridation to Calgary, Canada. Dr Ghali’s presentation to recent Calgary City Council hearings on fluoridation has been promoted by anti-fluoridation activists.

In my recent article Scientific integrity requires critical investigation – not blind acceptance I expressed some concerns with arguments presented by Dr Ghali in his presentation to the Calgary City Council. The video accompanying the article is one that the Fluoride Action Network and Fluoride Free NZ are using in their campaign against community water fluoridation. A campaign which currently concentrates on misrepresentation of recent fluoride-IQ studies – and resorts to blatant scaremonger.

I offered Dr Ghali a right of reply to my article and he has sent me the following. As it arrived in an email form I have edited it slightly but not changed any of the arguments.


I appreciate your indicating in your email below that you sensed that the recent video posted by the Fluoride Action Network might be presenting just a portion of my comments, without the context of my full presentation (and the presentation of key public health colleagues) at the recent City of Calgary committee meeting on community water fluoridation.  That is indeed the case, and I would greatly appreciate your taking a look at the entire presentation if you have time to do so.  Also, the presentation should be viewed in relation to the full O’Brien Institute report on CWF (that I attach for your convenience).

The link to the full special council meeting is below.  Our O’Brien Institute presentations begin at approximately 17 minutes into the 9 hour meeting, and our main presentations last for 55 minutes followed by some Q&A.  We then reappear as a panel (that includes AHS public health leaders) at about 6h40m into the video.

https://pub-calgary.escribemeetings.com/Players/ISIStandAlonePlayer.aspx?ClientId=calgary&FileName=2019-10-28.mp4

At a high level, we tried in our presentations to shed some light on the controversy, and to show how advocacy positions have focused on attacking both the evidence on benefits of fluoride (e.g., the multi-pronged attacks on Lindsay McLaren’s study on CWF), and the more recent evidence on potential negative cognitive effects in developing brains.

I must say that this journey into the fluoride issue has been quite eye opening, as it exposes the challenge of making sense out of a complicated controversy (– which is, interestingly, the name of your organization…[in my email I had included my position as a scientific advisor for Making Sense of Fluoride]).  You will see in the opening part of my presentation to the City of Calgary that there is an interesting and extensive body of literature on the challenge of integrating science and advocacy (and balancing science vs. advocacy).   The matter of CWF is a particularly challenging one in that regard, as the strong attacks on, for example, the CWF cessation studies (including Lindsay McLaren’s), are rooted in positional anti-fluoride advocacy, just as the unusually vigourous attacks on the fluoride cognition studies are seemingly rooted in the challenging findings of those studies (– both MIREC and ELEMENT are, after all, both NIH-funded prospective cohort studies unlike any of the prior cognition studies, that despite some limitations are clearly also more notable studies than the cognition studies that preceded them).

The O’Brien Institute was tasked with providing Calgary City Council with a non-positional description of the existing studies and evidence.  The new cognition studies (led, interestingly, by two Canadian public health research teams) and the ensuing NTP draft report from the US are now such that it would have been absurd for us to pretend that the new studies do not even exist or that they are fatally flawed with irrelevant results.

Do watch the entirety of the City of Calgary CWF committee meeting, and let me know if you would like to have a chat some time.   And thank you again for your email.


I am still concerned about the way Dr Ghali presents this issue but he also raises an important point about advocacy which needs discussion. So I will be responding to this post with a blog article ion a few days.

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Sleep disorders and fluoride: dredging data to confirm a bias

Sleep disorders are common and have many causes. But anti-fluoride activists will now be blaming them on community fluoridation. Image credit: Sleep Disorders and Problems

There is a pattern to the recent research aimed at finding a link between fluoridation and cognitive deficits, ADHD prevalence or possible thyroid problems. These researchers are simply using large databases from recent health surveys (ELEMENT in Mexico City, MIREC in Canada, INMA in Spain, and NHANES in the USA). Connecting these up with available measurements of drinking water fluoride, their own measurements of urinary or blood plasma fluoride using stored samples from the surveys, or even their own unvalidated estimates of fluoride dietary intake, they then search for statically significant (p < 0.05) relationships.

This gives them a large amount of data to search for effects – and as the p-hacking tool in my recent article, Statistical manipulation to get publishable results, shows – they will, of course, find them. They might have to use different fluoride measure to get a statistically significant result – but they have several to choose from: drinking water F, community water fluoridation, urinary F for the individual or his/her mother, blood plasma F and their own subjective estimate of dietary F intake.

In my last article, Some fluoride-IQ researchers seem to be taking in each other’s laundry, I discussed the biased peer-review process used in a new paper from the research and commented:

“One might expect that the need to use an open-access journal like Environmental Health and to choose “in-house” peer-reviewers indicates that the quality of the paper might not be the best.”

I was correct – this is another poor quality paper on fluoride and health effects which make unwarranted claims – and which will be used by anti-fluoride activists in their campaign against community water fluoridation.

This is the paper citation:

Malin, A. J., Bose, S., Busgang, S. A., Gennings, C., Thorpy, M., Wright, R. O., … Arora, M. (2019). Fluoride exposure and sleep patterns among older adolescents in the United States : a cross-sectional study of NHANES 2015 – 2016. Environmental Health, 1–9.

Multiple parameters to dredge

The researchers had a list of parameters to work with. Sleep duration, sleep apnea symptoms, snoring, daytime sleepiness (subdivided into rarely, sometimes, often and almost always), trouble sleeping, bedtime and wake time. Ten sleep disorder measures. The authors searched for statistically significant relationships of these with two fluoride measures: household tap water fluoride and blood plasma fluoride.

See the problem here? If not have a look at Statistical manipulation to get publishable results, and have a go with the p-hacking tool.

Blood plasma fluoride

In a bit of special pleading involving subgroups divided by gender they report:

“Among males, higher plasma fluoride concentrations were associated with higher odds of reporting sleep apnea symptoms, although this did not reach the threshold for statistical significance (uncorrected p = 0.17).”

And added:

“Plasma fluoride concentrations were not significantly associated with any of the other sleep outcome measures examined herein”

So nothing here. Despite using ten different sleep disorder measures and looking at subgroups there were no statistically significant relationships with blood plasma F.

Water fluoride

The tap water fluoride concentrations were mostly below 0.7 mg/L with mean and median values of 0.35 and 0.29 mg/L. There was no differentiation between community water fluoridated and non-fluoridated areas, but water fluoridation covers a high proportion of US citizens.

The only statistically significant relations shown by regression analyses were for sleep apnea, snoring, bedtime and waketime. Two out of ten sleep disorder measures or four out of ten if one counts different bedtime and waketime as disorders.

Bedtime and wake time

The paper reports that:

“fluoride exposure may be associated with shifts in the sleep-wake cycle, as higher water fluoride concentrations were associated with later weekday bedtime and wake time, but not sleep duration. Specifically, for each 0.52 mg/L increase in adolescents’ water fluoride concentrations, they tended to report going to bed 24-min later and getting out of bed 26-min later. “

 

Why should a different bedtime or wake time be considered sleep disorders – especially as no change in sleep duration occurs?

I think they are indulging in special pleading by attempting to find a reason for this in calcification of the pineal gland. This idea rests on an old observation that calcified pineal glands taken from elderly cadavers are high in fluoride. This is easily explained by the fact that fluoride is attracted to active calcified tissue. Calcification is caused by old age, calcium and phosphorus – not by fluoride. Fluoride is adsorbed by calcified tissue after calcification.

They do acknowledge as a limitation of their work that:

“participants were older adolescents who may be prone to sleep disruptions for various reasons, including playing video games, studying, working at jobs or having social influences, for example.”

Well, yes. And these social influences, jobs, etc., will be more common for adolescents living in cities which are more likely to have community water fluoridation than in rural and small-town areas.

Why were such “sleep disturbances” even included in their study? And why indulge in such fanciful reasoning to “explain” the result.

Snoring

The authors report that:

“each 0.52 mg/L increase in household tap water fluoride concentration was associated with a 38% reduction in the likelihood of male adolescents reporting snoring.”

Maybe young men living in cities and having an active social life are less likely to admit to snoring than their counterparts in rural areas. But the authors again indulge in fanciful reasoning by speculating:

“that our findings may point to a role of fluoride exposure in disrupting this deep sleep stage, thereby reducing opportunities for snoring.”

Or, alternatively”

“another possibility is that the gains in oral health from consumption of fluoridated water may protect against tonsillar infections that can contribute to snoring .”

Perhaps surprising that they are discussing a possibility of beneficial effects of fluoridation but they concede that:

” Future studies are needed to explore potential mechanisms by which fluoride exposure may reduce self-reported snoring.”

Perhaps a more reasonable future study will find absolutely no effect of fluoridation on reported snoring if it includes more relevant factors in its multiple regressions. Remember how Malin & Till (2015) reported a significant positive relationship between fluoridation extent and ADHD prevalence in the USA – yet when more relevant factors where included in the multiple regression the relationship with fluoridation disappear (see Perrott 2018).

Sleep apnea

Only about 10% of the participants reported symptoms of sleep apnea at least once a week. Yet the paper report they found:

“that each 0.52 mg/L increase in household tap water fluoride concentration was associated with a 1.97 times higher likelihood of adolescents reporting having experienced symptoms suggestive of sleep apnea at least once per week.”

Well, there was a very large spread in the data with a confidence interval of 1.27 to 3.05.

On this basis they argue:

“This suggests that fluoride exposure at population-relevant levels may be a risk factor for sleep disturbances; however, additional studies are needed to explore this possibility, given the scarcity of data on this topic.”

Again, perhaps a more reasonable future study will find self-reported sleep apnea is related to living in a city or some other factor rather than fluoride. The results found in this study should not be used to argue that sleep apnea is caused by fluoridation. But, of course, that will not stop the anti-fluoridation activists from doing so.

Speculation without action is arrogant

I submitted a paper to a journal once where I speculated on mechanisms which could explain the associations I had found. One of the peer-reviewers pointed out that speculation was worthless in itself and that I should actually do some measurements to test the proposed mechanism before publication.

The reviewer was quite right – it was arrogant of me to think that my speculation had any scientific worth when it was not supported by data. I was simply resting on an assumed authority or credibility. But most proposed ideas in science turn out to be wrong. Speculation only has value when it is converted to a hypothesis and tested.

I did the experiment to test my speculated hypothesis, included it in my revised paper which was then published (and turned out to be a more valuable contribution). Perhaps this sleep disorder paper would have had more significance if one of the peer reviewers had made a similar comment and the authors had then set out to test some of their speculations. But fat chance of that happening when the peer-reviewers were selected from colleagues who already have a bias for finding similar effects of fluoride (see Some fluoride-IQ researchers seem to be taking in each other’s laundry).

The problem with this sleep disorder paper and other recent papers reporting relationships between fluoride and cognitive effects is that they are only reporting fishing expeditions. They simply report the results of searching through data sets containing a whole range of parameters to find statistically significant relationships. They put all their faith in the p-value so that the relationship appears important even when the effect size is small and explains a minuscule amount of the variability. In itself, a p-value can say absolutely nothing about the cause of an observed relationship or be used to claim an effect. That requires further work.

Nothing wrong with statistical fishing exhibitions like this. I also enjoy searching through data looking for relationships. But that is only the start. Identification of relationship can suggest research – experiments or survey aimed at identifying causes.

I don’t think there is any value in simply reporting the results of fishing expeditions without further research. Such papers only serve as an outlet for unwarranted and unsupported speculation – and as I say above that is arrogant. Why should anyone else take such speculation as evidence or identification of a cause?

Trouble is when one has a bias to confirm one can eagerly clutch at this sort of speculation and promote it as a real effect. When speculation like this is promoted by anti-vaccination or anti-fluoridation activists it can end up undermining effective social health policies – and that is bad.

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