Tag Archives: Mary Byrne

Why is it so difficult to get an open discussion on fluoridation?

Yes, I know – everyone’s mind is already made up so participants just talk past each other. People’s positions on this and similar issues have become a matter of identity – people are driven by emotions, not information.

But, the information is there – and while I agree many people are driven by emotions they often attempt to use that information to support their positions. In a sense, the information acts as a proxy for their real driving force – their emotions.

Nevertheless, I have always considered a good-faith scientific exchange on issues like this is possible. I believe the exchange I had with Paul Connett, a US anti-fluoride campaigner, four years ago was a good example of what is possible (see Fluoride Debate or download Connett & Perrott (2014) – the pdf document of the exchange).

So, I always look for the chance to repeat that discussion – and I thought that might happen with my recent articles discussing the Mexican maternal prenatal urinary F/child IQ study. Why, because my recent article Paul Connett’s misrepresentation of maternal F exposure study debunked got a response from Mary Byrne, National Coordinator of Fluoride Free New Zealand. I posted her article as Anti-fluoride group coordinator responds to my article.

I responded to that with Mary Byrne’s criticism is misplaced and avoids the real issues and again I offered her a right of reply.

But no response. In fact, she refuses to answer any of my emails.

OK, I can take a hint – but then I see her claiming on Facebook (see image above) that SciBlogs would not allow this discussion! Would not allow “exposure to both sides!” This is patently untrue and she is completely misrepresenting SciBlogs and me.

Note: SciBlogs is a collection of New Zealand science bloggers. My science-oriented blogs usually appear there by syndication.

The email exchange

So it is worth actually looking at the email exchange where Mary requested publication of her article and we responded. Please note the dates and times and excuse the low magnifications. Here are the emails in sequence:

11 March, 12:51 pm: Mary Byrne requests SciBlogs publish her response to my article.
11 March, 1:06pm: After internal passing on the email, Peter Griffin sends it to me.

Pretty quick service. Remember this was a Sunday.

My response was also pretty quick (considering I usually have my daily power nap at that time). I didn’t have to do much thinking about the issue (please excuse my verbosity).

11 March, 2.11 pm

Mary Byrne did not reply so I went ahead anyway and interpreted the original request to mean that a right of reply post on my blog was acceptable. Her article was posted on Tuesday, March 13 (I already posted on Monday and like to spread posts throughout the week) – Anti-fluoride group coordinator responds to my article. I emailed Mary to let her know her article was posted and I would respond to it.

I posted my promised response to her article on Wednesday, March 14th – Mary Byrne’s criticism is misplaced and avoids the real issues and sent Mary an email to let her know – once again offering her another right of reply.

So, Mary’s claim of SciBlogs not allowing exposure from both sides is completely false.

Incidentally, I have emailed Mary asking her to correct that misrepresentation. She has ignored my email, as she ignored all the other emails I have sent her about this issue. The misrepresentation is still on the Fluoride Free NZ Facebook page.

So, I do not expect Mary to continue this exchange, unfortunately. And I do regret she has chosen to misrepresent the situation in the way she has.

But I guess it is just another case of misrepresentation by an anti-fluoridation activist.

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Mary Byrne’s criticism is misplaced and avoids the real issues

Image credit: BuildGreatMinds.Com

First, thanks to Mary Byrne and FFNZ for this response (see Anti-fluoride group coordinator responds to my article). Hopefully, this will help encourage some good faith scientific discussion of the issues involved in my original article (Paul Connett’s misrepresentation of maternal F exposure study debunked). I am pleased to promote such scientific exchange.

I will deal with the issues Mary raised point by point. But first, let’s correct some misunderstandings. Mary claimed I am a “fluoride promoter” and had “sought to discredit the study via his blog posts and tweets.”

  1. I do not “promote fluoride.” My purpose on this issue has always been to expose the misinformation and distortion of the science surrounding community water fluoridation (CWF). I leave promotion of health policies to the health experts and authorities.
  2. I have not “sought to discredit the study.” The article Mary responded to was a critique of the misrepresentation of that study by Paul Connett – not an attack on the study itself. This might become clear in my discussion below of the study and how it was misrepresented.

The study

The paper we are discussing is:

Bashash, M., Thomas, D., Hu, H., Martinez-mier, E. A., Sanchez, B. N., Basu, N., … Hernández-avila, M. (2016). Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6 – 12 Years of Age in Mexico.Environmental Health Perspectives, 1, 1–12.

Anti-fluoride activists have leaped on it to promote their cause – Paul Connett, for example, claimed it should lead to the end of community water fluoridation throughout the world! But this is not the way most researchers, including the paper’s authors, see the study. For example, Dr. Angeles Martinez-Mier, co-author and one of the leading researchers,  wrote this:

1. “As an individual, I am happy to go on the record to say that I continue to support water fluoridation”
2. “If I were pregnant today I would consume fluoridated water, and that if I lived in Mexico I would limit my salt intake.”
3.  “I am involved in this research because I am committed to contribute to the science to ensure fluoridation is safe for all.”

Was the reported association statistically significant?

Mary asserts:

“Perrott claims that the results were not statistically significant but his analysis is incorrect.”

That is just not true. I have never claimed their reported association was not statistically significant.

I extracted the data they presented in their Figures 2 and 3A and performed my own regression analysis on the data. This confirmed that the associations were statistically significant (something I never questioned). The figures below illustrating my analysis were presented in a previous article (Maternal urinary fluoride/IQ study – an update). These results were close to those reported by Bashash et al., (2017).

For Fig. 2:

My comment was – “Yes, a “statistically significant” relationship (p = 0.002) but it explains only 3.3% of the variation in GCI (R-squared = 0.033).”

For Fig 3A:

My comment was – “Again, “statistically significant” (p = 0.006) but explaining only 3.6% of the variation in IQ (R-squared = 0.0357).”

So I in no way disagreed with the study’s conclusions quoted by Mary that:

” higher prenatal fluoride exposure, in the general range of exposures reported for other general population samples of pregnant women and nonpregnant adults, was associated with lower scores on tests of cognitive function in the offspring at age 4 and 6–12 y.”

I agree completely with that conclusion as it is expressed. But what Mary, Paul Connett and all other anti-fluoride activists using this study ignore is the real relevance of this reported association. The fact that it explains only about 3% of the IQ variance. I discussed this in the section The small amount of variance explained in my article.

This is a key issue which should have been clear to any reader or objective attendee of Paul Connett’s meeting where the following slide was presented:

Just look at that scatter. It is clear that the best-fit line explains very little of it.  And the 95% confidence interval for that line (the shaded area) does not represent the data as a whole. The comments on the statistical significance and confidence intervals regarding to the best-fit line do not apply to the data as a whole.

Finally, yes I did write (as Mary quotes) in my introductory summary that “the study has a high degree of uncertainty.” Perhaps I should have been more careful – but my article certainly makes clear that I am referring to the data as a whole – not to the best fit line that Connett and Mary concentrate on. The regression analyses indicate the uncertainty in that data by the low amount of IQ variance explained (the R squared values) and the standard error of the estimate (about 12.9 and 9.9 IQ points for Fig 2 and  Fig 3A respectively).

The elephant in the room – unexplained variance

Despite being glaringly obvious in the scatter, this is completely ignored by Mary, Paul Connett and other anti-fluoride activists using this study. Yet it is important for two reasons:

  • It brings into question the validity of the reported statistically significant association
  • It should not be ignored when attempting to apply these findings to other situations like CWF in New Zealand and the USA.

Paul Connett actually acknowledged (in a comment on his slides) I was correct about the association explaining such small amount of the variance but argued:

  • Other factors will be “essentially random with respect to F exposure,” and
  • The observed relationship will not be changed by the inclusion of these other factors.

I explained in my article Paul Connett’s misrepresentation of maternal F exposure study debunked how both these assumptions were wrong. In particular, using as one example the ADHD-fluoridation study I have discussed elsewhere (see Perrott, 2017). I hope Mary will refer to my article and discussion in her response to this post.

While ignoring the elephant in the room – the high degree of scattering, Mary and others have limited their consideration to the statistical significance and confidence intervals of the reported association – the association which, despite being statistically significant, explains only 3% of the variation (obvious from the slide above.

For example, Mary quotes from the abstract of the Bashash et al., (2017) paper:

“In multivariate models we found that an increase in maternal urine fluoride of 0.5mg/L (approximately the IQR) predicted 3.15 (95% CI: −5.42, −0.87) and 2.50 (95% CI −4.12, −0.59) lower offspring GCI and IQ scores, respectively.”

I certainly agree with this statement – but please note it refers only to the model they derived, not the data as a whole. Specifically, it applies to the best-fit lines shown in Fig 2 and Fig 3A as illustrated above. The figures in this quote relate to the coefficient, or slope, of the best fit line.

Recalculating from 0.5 mg/L to 1 mg/L this simply says the 95% of the coefficient values, or slopes, of the best fit lines resulting from different resampling should be in the range  -10.84 to -1.74 CGI (Fig 2) and -8.24 to 1.18 IQ (Fig 3A).

[Note – these are close to the CIs produced in my regression analyses described above – an exact correspondence was not expected because digital extraction of data from an image is never perfect and a simple univariate model was used]

The cited CI figures relate only to the coefficient – not the data as a whole. And, yes, the low p-value indicates the chance of the coefficient, or slope, of the best-fit line being zero is extremely remote. The best fit line is highly significant, statistically. But it is wrong to say the same thing about its representation of the data as a whole.

This best-fit line explains only 3% of the variance in IQ – and a simple glance at the figures shows the cited confidence intervals for that line simply do not apply to the data as a whole.

The misrepresentation

That brings us back to the problem of misrepresentation. We should draw any conclusions about the relevance of the data in the Bashash et al., (2017) study from the data as a whole – not just from the small fraction with an IQ variance explained by the fitted line.

Paul Connett claimed:

“The effect size is very large (decrease by 5-6 IQ points per 1 mg/L increase in urine F) and is highly statistically significant.”

But this would only be true if the model used (the best-fit line) truly represented all the data. A simple glance at Fig 2 in the slide above shows that any prediction from that data with such a large scatter is not going to be “highly statistically significant.” Instead of relying on the CIs for the coefficient or slope of the line, Connett should have paid attention to the standard error for estimates from the data as a whole given in the Regression statistics of the Summary output. – For Fig. 2, this is 12.9 IQ points. This would have produced an estimate of “5-6 ± 36 IQ points which is not statistically significantly different to zero IQ points,”  as I described in my article

Confusion over confidence intervals

Statistical analyses can be very confusing, even (or especially) to the partially initiated. We should be aware of the specific data referred to when we cite confidence intervals (CIs).

For example, Mary refers to the CI values for the coefficients, or slopes, of the best fit lines.

Figs 2 and 3A in the Bashash et al., (2017) paper include confidence intervals (shaded areas) for the best fit lines (these take into account the CIs of the constants as well as the CIs of the coefficients). That confidence interval describes the region of 95% probability for where the best-fit line will be.

Neither of those confidence intervals applies to the data as a whole as a simple glance at Figs 2 and 3A will show. In contrast, the “prediction interval” I referred to in my article, does. This is based on the standard error of the estimate listed in the Regression statistics. Dr. Gerard Verschuuren demonstrated this in this figure from his video presentation.

Mary is perfectly correct to claim “it is the average effect on the population that is of interest” – but that is only half the story as we are also interested in the likely accuracy of that prediction. The degree of scatter in the data is also relevant because it indicates how useful this average is to any prediction we make.

Given the model described by Bashash et al., (2017) explained only 3% of the IQ variance, while the standard error of the estimate was relatively large, it is misleading to suggest any “effect size” predicted by that model would be “highly significant” as this ignores the true variability in the reported data. When this is considered the effect size (and 95% CIs) is actually “5-6 ± 36 IQ points which is not statistically significantly different to zero IQ points,”

Remaining issues

I will leave these for now as they belong more to a critique of the paper itself (all published papers can be critiqued) rather than the misrepresentation of the paper by Mary Byrne and Paul Connett. Mary can always raise them again if she wishes.

So, to conclude, Mary Byrne is correct to say that the model derived by Bashash et al., (2017) predicts that an increase of “fluoride level in urine of 1 mg/L could result in a loss of 5-6 IQ points” – on average. But she is wrong to say this prediction is relevant to New Zealand, or anywhere else, because when we consider the data as a whole that loss is “5-6 ± 36 IQ points.”

I look forward to Mary’s response.

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Anti-fluoride group coordinator responds to my article

Image credit: Debate. The science of communication.

My recent article Paul Connett’s misrepresentation of maternal F exposure study debunked got some online feedback and criticism from anti-fluoride activists. Mary Byrne, National coordinator Fluoride Free New Zealand, wrote a response and requested it is published on SciBlogs “in the interests of putting the record straight and providing balance.”

I welcome her response and have posted it here. Hopefully, this will satisfy her right of reply and help to develop some respectful, good faith, scientific exchange on the issue.

I will respond to Mary’s article within a few days.

Perrott wrong. New US Government study does find large, statistically significant, lowering of IQ in children prenatally exposed to fluoride

By Mary Byrne, National coordinator Fluoride Free New Zealand.

While the New Zealand Ministry of Health remains silent on a landmark, multi-million-dollar, US Government funded study (Bashash et al), and the Minister of Health continues to claim safety based on out-dated advice, fluoride promoter Ken Perrott has sought to discredit the study via his blog posts and tweets.

Perrott claims that the results were not statistically significant but his analysis is incorrect.

The conclusion by the authors of this study, which was published in the top environmental health journal, Environmental Health Perspectives, was:

In this study, higher prenatal fluoride exposure, in the general range of exposures reported for other general population samples of pregnant women and nonpregnant adults, was associated with lower scores on tests of cognitive function in the offspring at age 4 and 6–12 y.”

Perrott states the study has “a high degree of uncertainty”. But this contrasts with the

statistical analysis and conclusion of the team of distinguished neurotoxicity researchers from Harvard, the University of Toronto, Michigan and McGill. These researchers have written over 50 papers on similar studies of other environmental toxics like lead and mercury.

RESULTS: In multivariate models we found that an increase in maternal urine fluoride of 0.5 mg/L (approximately the IQR) predicted 3.15 (95% CI: −5.42, −0.87) and 2.50 (95% CI −4.12, −0.59) lower offspring GCI and IQ scores, respectively.

The 95% CI is the 95% Confidence Interval which is a way of judging how likely the results of the study sample reflect the true value for the population. In this study, the 95% CIs show the results are highly statistically significant. They give a p-value of 0.01 which means if the study were repeated 100 times with different samples of women only once could such a large effect be due to chance.

Perrott comes to his wrong conclusion because he has confused Confidence Intervals with Prediction Intervals and improperly used Prediction Intervals to judge the confidence in the results. A Prediction Interval is used to judge the confidence one has in predicting an effect on a single person, while a Confidence Interval is the proper measure to judge an effect on a population. In epidemiological studies, it is the average effect on the population that is of interest, not how accurately you can predict what will happen to a single person.

Despite the authors controlling for numerous confounders, Perrott claimed they did not do a very good job and had inadequately investigated gestational age and birth weight.

Once again Perrott makes a fundamental mistake when he says that the “gestational period < 39 weeks or > 39 weeks was inadequate” and “The cutoff point for birth weight (3.5 kg) was also too high.”

Perrott apparently did not understand the Bashash paper and mistook what was reported in Table 2 with how these covariates were actually treated in the regression models. The text of the paper plainly states:

“All models were adjusted for gestational age at birth (in weeks), birthweight (kilograms)”

Thus, each of these two variables were treated as continuous variables, not dichotomized into just two levels. Perrott’s criticism is baseless and reveals his misunderstanding of the Bashash paper.

Perrott states that the results are not relevant to countries with artificial fluoridation because it was done in Mexico where there is endemic fluorosis. But Perrott is wrong. The study was in Mexico City where there is no endemic fluorosis. Furthermore, the women’s fluoride exposures during pregnancy were in the same range as found in countries with artificial fluoridation such as New Zealand.

The study reports that for every 0.5 mg/L increase of fluoride in the urine of the mothers there was a statistically significant decrease in average IQ of the children of about 3 IQ points. It is therefore correct to say that a fluoride level in urine of 1 mg/L could result in a loss of 5 – 6 IQ points. This is particularly relevant to the New Zealand situation where fluoridation is carried out at 0.7 mg/L to 1 mg/L and fluoride urine levels have been found to be in this range2.

There is no excuse for Health Minister, David Clark, to continue to bury his head in the sand. This level of science demands that the precautionary principle be invoked and fluoridation suspended immediately.

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Declan Waugh scaremongers over fluoride – again

Mary Byrne, the convener of the anti-fluoridation activist group Fluoride Action Network of NZ, is promoting “alarming information” about incidence of neural tube developmental defects like spina bifida with the implication they are caused by community water fluoridation. Her authority for this is Declan Waugh!


Declan Waught – promoted as a “leading expert” on fluoride by anti-fluoride movement

Any critical examination of Waugh’s claims on fluoridation (and there are many) would show him to be the last person one should trust on the issue. Unfortunately, though, he does seem to fool some people – using a mixture of extensive, but misleading, citation of scientific papers and claims about the high incidence of many illnesses in the Republic of Ireland. Anti-fluoride activists love to quote him as “scientific proof” for their own extreme claims and, worryingly, the Hamilton City Council was persuaded that he is indeed a reliable “expert” – citing one of his reports in the list of 10 documents which convinced them to stop fluoridation last year (see When politicians and bureaucrats decide the science).

Very often simple checking will show his claims about the incidence of illnesses are actually completely wrong, and the scientific papers he cites don’t actually say what he claims. Completely dishonest but  it seems you can fool some of the people some of the time with fancy sciency-looking reports. Especially if your citations are so intimidatingly extensive few readers have the energy to check them.

Here I will take apart the fear mongering he is currently promoting over spina bifida and similar neural defects.

The incidence of neural defects in Ireland

The “alarming information” on incidence of neural defects in The Republic of Ireland  he relies on is a paper by McDonnell et al (2014), Neural tube defects in the Republic of Ireland in 2009–11.  The authors concluded:

“The incidence of NTDs [neural tube defects] in the Republic of Ireland appears to be increasing. Renewed public health interventions, including mandatory folic acid food fortification, must be considered to reduce the incidence of NTD.”

A press release from the UCD School of Medicine and Medical Science in Dublin put this in context:

“This comprehensive national audit over three years found that the incidence of neural tube defects (NTDs) increased slightly during the period studied, reversing the trend of the previous ten years.

NTD incidence had increased from 0.92/1 000 in 2009 to 1.17/1 000 in 2011. And nowhere was fluoride implicated as a cause of this.

So no basis for Waugh’s fear mongering and implication of community water fluoridation as the cause. However, I imagine the average anti-fluoride activist would be aghast at the idea of a social health policy involving mandatory folic acid food fortification and would campaign against it.

Manufacturing a link to fluoride

Declan Waugh manufactures a link of NTDs to fluoride and community water fluoridation in two ways:

1: The old trick of using a brief report from an area of high dietary fluoride intake. In this case the paper of Gupta et al (1994). This brief 2 page report studied children suffering dental and skeletal fluorosis in India. Drinking water concentration was high (4.5 to 8.5 ppm compared with the recommended 0.7 for community water fluoridation). Fourteen of the 30 children studied showed spinal bifida occulta (the mildest form which usually presents no problems) on X-rays but not on clinical examination.

Although the incidence in this small sample is higher than the 20% normally found in average spines the number of subjects is low so no conclusions are possible. In fact, all the authors did was to propose “a randomised controlled study to evaluate a possible correlation between spina bifida and high fluoride intake.” The also pointed out that they could not find any literature reports correlating spina bifida with fluoride.

So all pretty speculative – but enough for a desperate anti-fluoride “authority” like Declan Waugh to do a bit of scaremongering.

2: Waugh goes out of his way to suggest a mechanism for community water fluoridation causing neural tube defects – fluoride reduces folic acid concentration in the body! And he manages to cite a couple of scientific papers to support his ideas. Problem is – they don’t.

He argues in a 2012 report (which he describes as his “main report”) that “Fluoride is known to be an inhibitor of enzymatic activity and research has identified fluoride as an inhibitor of homocysteine hydrolase363 and this causes a decline in folic acid levels.

The cited paper is Mehdi S, Jarvi ET, Koehl JR, McCarthy JR, Bey P. The mechanism of inhibition of S-adenosyl-L-homocysteine hydrolase by fluorine-containing adenosine analogs. J Enzyme Inhib. 1990;4(1):1-13.

Waugh is citing work using “fluoride-containing adenosine analogs” to make the claim about the fluoride anion. Specifically, the compounds (Z)-4,5′-Didehydro-5′-deoxy-5′-fluoroadenosine, 5′-deoxy-5′-difluoroadenosine, and 4′,5′-didehydro-5′-deoxy-5′-fluoroarabinosyl-adenosine  – not fluoride.

Extremely sloppy!

Declan Waugh has just pulled out any old citation referring to fluoride – maybe he hasn’t even read past the title of the paper.

Yet the tame alternative health media make the claim that “amongst the international scientific community, Waugh is now regarded as a leading expert on the subject!”

That reminds me of the local anti-fluoridation activists who continually describe Paul Connett, from the sister activists organisations Fluoride Alert, as a “World expert on fluoridation!”

Actually, Waugh gave the show away in his 2013 report when he said:

“To my knowledge no study has ever been undertaken to examine if fluoride exposure combined with nutritional status may be a contributory factor to the alarming levels of congenital defects in fluoridated compared to non-fluoridated countries.”

But as is often the case with these sorts of admissions, the very lack of evidence appears to be used to infer a cause. He is advancing the fallacy that the lack of evidence really means the evidence is there but just hasn’t been found yet – probably because evil scientists are conspiring to prevent the necessary research.

The old trick of making a wild claims, suggesting something as a possibility and then promoting the idea as some sort of scientifically proven fact in his scaremongering.

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Fluoridation debate: Why I support fluoridation – 2nd reply to Connett

This is Ken Perrott’s response to Paul Connett’s second criticism of Ken’s article Fluoride Debate: Why I support fluoridation – 2nd response from Connett.

For Ken Perrott’s original article see – Fluoride debate: Why I support fluoridation.

It is a pity that Paul Connett chose to ignore the ethical question of balancing personal choice and social good because he took my comments on this as a personal criticism of him. They were not meant to be. I am happy to discuss the science but, in the end, science cannot make ethical and values decisions for us. Yes, it can, and should, inform those decisions – but pretending they are only about science does a disservice to science and to ethics.

Unfortunately science is often used in these sort of debates as a proxy for values issues. Professor Gluckman pointed that out in his statement What is in the water?  An excellent article by Tania Ritchie in Science and Society outlines the dangers of this approach (see  The fluoridation debate: why we all lose when we pretend it’s just about science). She shows how using science as a proxy backs people into pseudoscientific corners (and that is certainly an issue for these opposing fluoridation). It also places an impossible demand of certainty on science (“prove to me beyond doubt that fluoride at optimal concentrations is completely safe – if in doubt leave it out”). And concentration on the science often disguises poor ethical positions. She concludes:

“Using good science to counter bad science is productive. Using good science to tell us what will happen if we make a certain decision is also, of course, vital. But pretending science can tell us what decision we should make, or trying to counter ethical concerns with science, will never be helpful.”

Well, for the moment I guess I am opting for “using good science to counter bad science” but I hope we can return to these ethical issues at some stage.

Nature of bioapatites and systemic role for fluoride

Paul seems not to have taken on board my description of the structural role of fluoride in apatites and the recognised beneficial role of ingested fluoride. (Perhaps he considered that section was somehow a personal criticism and should be ignored.)

Mind you, I keep coming across that problem with other anti-fluoride  activists. They wish to talk only about topical application of fluoride, and ignore completely the beneficial effects of ingested fluoride. This seems to create reading, hearing and comprehension problems for them. So I get accused of advocating that suntan lotion should be drunk or similar attempts at humour!

However, it is a critical feature of this debate so I will just start this response by briefly repeating a few things.

  • Fluoride is a normal, natural component of bioapatites. In the real world these don’t exist as end-member compounds such as hydroxylapatite or fluoroapatite. They are more correctly described as hydroxyl-fluoro-carbonate-apatites.
  • Accumulation of fluoride, together with calcium and phosphate, in our bioapatites is a normal part of development. This is beneficial because it helps strength our bones and teeth, and lowers their solubility.
  • Both insufficient fluoride, or excess fluoride in our bioapatites can cause problems.
  • Excessive dietary intake can result in excessive fluoride in our bones and teeth. Insufficient intake may also cause our bioapatites to be weaker and more prone to dissolve. When dietary intake of fluoride is reduced fluoride can be lost from bones and calcified tissues.
  • The scientific literature reports that fluoride has a systemic role benefitting bones and pre-erupted teeth

Surface mechanisms for reducing tooth decay

We seem to be making a little progress here with the so-called “topical” mechanism – but only a little and very grudgingly. Paul has apologised for misrepresenting my explanation of the surface mechanism for the action of fluoridated water in countering tooth decay in existing teeth. He acknowledges that I was discussing the transfer of fluoride to saliva from water during drinking water, and not the smaller concentrations coming from the salivary glands after ingestion.

In this I was simply reporting what I have read in the scientific literature.  But Paul will still have none of that. He concedes that fluoride in saliva “may or may not do something” and presents his own “simple personal observations” to claim that there is little chance of drinking water mixing with saliva. Not the first time I have heard this argument – and it always brings a picture to mind of a committed anti-fluoride activist drinking their water through a tube down the throat. I leave it to readers to observe their own drinking behaviour and decide if drinking water has little chance of mixing with saliva – or transferring ions to saliva.

So it is one step forward and another step back. Made worse by his assertion (from personal experience) “that the fluoride ions have little opportunity to form a biofilm on any teeth other than the back of the front teeth.” Of course the fluoride does not form a biofilm. It and other ions in the water and saliva do, however, transfer to, and diffuse through, existing biofilms (plaque) on the teeth.

There are quite a few reports of the effect of regular consumption of fluoridated water increasing the F concentrations in saliva and plaque both after ingestion (eg Cury & Tenuta 2008Martínez-Mier 2012) and directly Featherston 2000Bruun & Thylstrup 1984). (Yes, I realise that the CDC sates that the ingested fluoride delivered to saliva “is not likely to affect cariogenic activity” and this is echoed by other writers. However, there still seem to be workers who argue this does contribute and I am aware of laboratory experiments showing the mechanism can work at very low fluoride concentrations. But this is a detail I will leave to the experts – it doesn’t affect the current exchange).

Loaded language and scientific knowledge

Paul again refers to advances of scientific knowledge in a sneering way. He claims that the CDC “admitted” that research indicated the prevention of dental caries by fluoride occurs by a topical mechanism in existing teeth. He also speculates that the CDC “was scrambling to salvage some kind of role for fluoridated water . . . Despite its admission of the predominance of the topical effect.” Can somebody with research experience in chemistry really see scientific progress as some sort of winning-out over a conspiracy to ignore the “truth?”

Mary Byrne, a local anti-fluoridation spokesperson, shows a similar apparent misunderstanding of the nature of scientific knowledge when she describes, disparagingly,  this progress in understanding as scientists being “wrong for fifty years.” She keeps repeating this even though her error has been explained to her.

These characterisations are like saying Newton was wrong with his laws of motion or that he was somehow hiding the truth and Einsteinian relativity  is simply a case of scientists being forced to “admit”, or “concede” they were wrong – as if they had hidden something!

Use of loaded language like this has a political purpose which interferes with proper understanding of the science.

The journal Fluoride

Paul describes my comments about the journal Fluoride, and its editors, as “derogatory,” and accuses me of “double standards.” I think that shows a sensitivity and inability to consider my comments objectively. Not surprising, as Paul has some “irons in the fire” on this issue.

I said that “if I had some credible findings in fluoride chemistry and wished to present a paper to the scientific community for their consideration Fluoride is the last journal I would choose.” This isn’t completely hypothetical because I have published a few papers on fluoride chemistry. So how do I decide where to publish my work?

Firstly, my fluoride work was relevant to pedology and soil chemistry so it was natural to consider soil science journals. This was the audience to aim for and our work was of direct relevance to readers of those journals. I doubt that many of our intended audience or their institutes subscribed to, or read, Fluoride.

But, today if I were considering a general  journal and had a look at Fluoride what would I find. First of all the website (where I would go to judge the journal’s scope, requirements and refereeing policy) – seriously, does this show a credible scientific society or editorial office?


This is what greets you as the home page for the Fluoride journal (http://www.fluorideresearch.org/)

That extremely amateurish web page puts me off – perhaps there are other general journals dealing with fluoride (contrary to Paul’s claim). Let us see if Journal of Fluoride Chemistry is better? See the difference?


Home page for the Journal of Fluorine Chemistry

Secondly, a quick skim of accepted papers in Fluoride indicates many are related to areas where fluoride toxicity is a problem because natural levels are high or excessive. The quality of many of these papers appears poor, a common problem where there are many authors whose main language is not English. It has a predominantly “third World” appearance. This would also raise a flag about possibly low standards of editorial review. Have a look at the list of contents for one of the 2007 issues.

None of these factors would attract me as a working and publishing scientist concerned at establishing a publication record in high quality and credible journals.

However, if I was a non-English speaker with routine work which I might find difficulty publishing elsewhere, and especially if that work was related to areas where natural fluoride levels were high, I would probably consider the journal. With the realisation in the back of my mind that I would probably have no luck with submission to a more reputable journal.

Now, I am not being “personal” or “derogatory” in making  that realistic evaluation. Nor do I think there are “double standards’ in choosing a good journal for publication. Good work deserves a good journal for publication.

Paul effectively concedes this in referring to attempts by Xiang et al to get their work published in a more reputable journal. He laments the fact that this journal would not include material already published in Fluoride (standard procedure in the publishing world) as amounting to Xiang’s material being “withheld from the mainstream scientific community.” (Paul obviously agrees that Fluoride does not have a good standing in the mainstream scientific community). The lesson being that Xiang should have gone for the reputable journal first time around. Why publish in a journal which does not give access to “the mainstream scientific community” if one’s work is good enough to get published in a reputable journal

That is a sensible question – not a derogatory one.

Connett’s relation with Fluoride

It is instructive to look at Paul Connett’s own publications in Fluoride. He claims to have researched the issue for 17 years and I would expect that at least some of his research papers would have ended up in this journal.

A simple search for the name Connett showed me a couple of guest editorials – often coauthored with editors of the journal (see for example Professionals moblize to end water fluroidation and Misplaced trust in official reports), a book review (coauthored with editors of the journal), reports of the International Fluoride Society (IFS – owner of Fluoride) conferences. There were abstracts of papers or posters presented at IFS conferences authored by Paul, Ellen and Michael Connett – but no sign of formal papers for these. (I hope Paul will correct me and provide links if I have missed papers with full text.)

This at least tells me that Paul is on excellent terms with those editing and running this journal. Not surprising when one looks at the names in the editorial board of the journal, the western contributors to the journal and the names on the advisory board of Paul’s activist organisation Fluoride Alert.

Another thing that stands out for me about the editorial and advisory boards is the large number of retired, former, emeritus academics (around 17 from a glance). In the past I have also noticed this about the organisations and petitions of climate change climate contrarians/deniers/pseudosceptics. As a retired scientist myself I can appreciate how such issues can become hobbies, and avenues for social involvement and personal standing for people who formerly relied on their employment and professional standing for such things. I can also appreciate that retirement often also means loss of contact with current research and findings. This increases my suspicions of the journal and organisation.

There was one normal looking journal paper by Michael Connett Vulvar paget’s disease: recovery wihtout surgery following change to very low-fluoride spring and well water.” My impression is this was simply an anecdotal history for one person – probably not normally acceptable in a scientific journal (unless at least written by the practicing medical person handling the case). A quick search of Google Scholar shows this to be Michael’s sole scientific paper – perhaps not surprising as he is not a scientist. He is the Special Projects Director for the Fluoride action network, an attorney in Philadelphia, PA, and received his law degree from Temple Law School in 2011. But now has a scientific publication record!

(Note for non-scientists wishing to show a scientific publication record. There  are plenty of anecdotal stories on the internet by people claiming sensitivity to fluoride. Hell, the other day I read the personal account of one person with skeletal fluorosis which cleared up immediately he stopped drinking tap water! You could select your own “case history,” write it up as a scientific paper and submit to Fluoride. Mind you, your paper might not be all that visible to the “mainstream scientific community”).

Looking at Fluoride, Fluoride Alert and the International Society for Fluoride Research I get a strong impression of a group who take in each other’s laundry – but at the same time give publication space for some third world scientists who may not meet the standards of more reputable journals.

Paul gave it away when he reported to us that “the US National Institute of Health (NIH) has refused to cover the contents of this journal in PubMed.” Surely that tells us something about how this journal is considered by the science community (and please – if one has to resort to conspiracy theories to explain this the argument is surely already lost.)

Bones, hip fractures and the literature

Kurt Ferre’s comment about misrepresentation of the Li et al (2001) paper referred to Paul’s note on it in Fluoride Alert (Reason 29 of 50 reasons to oppose fluoridation). Here Paul did describe the data as relating to hip fractures and not over all fractures. OK, Paul in chapter 17 of his book may have been more specific but that is not what Kurt referred to. (By the way, I am still plodding through Paul’s book – on chapter 9 at the moment).

Paul claims I “prefer” an “interpretation” of the Li et al (2001) paper that there is a “sudden” appearance of hip fracture at a higher concentration rather than a linear increase from low concentrations. He is wrong – I don’t prefer any specific interpretation. I was merely pointing out what can be drawn from the statistical analysis of the data.

One of our commenters has already noted that Paul’s argument for his own intepretation of the data here amounts to special pleading – where he has to ignore, or denigrate, the statistical analysis. He is pleading when he writes that increases “appear to be ‘real’ even though they are not statistically signficant individually.” Or that the data “appear consistent with a linear regression. Statistical significance is not the final word on whether a data point or data set is real or not.”

These were the sort of statements I would put red lines through when I was reviewing papers submitted for publication.

However, this is a digression. The interpretation of the increase at higher concentrations is not important. The fact is neither overall fractures or hip fractures showed an increase at fluoride concentrations considered optimum for oral health.

It was clear to me when I originally read and wrote about  Li et al’s (2001)  paper (see  – Is fluoride an essential dietary mineral? ) that the increased incidence of overall fractures at concentrations below optimum did not refer to hip fractures. The authors specifically brought that to readers attention – “the data show a somewhat different pattern for hip fractures in relation to the water fluoride levels. . . Instead, the prevalence of hip fractures was stable until the water concentration reached 1.45–2.19 ppm.” They qualified this with “However, it may not be appropriate to conclude that the risk of hip fracture is more sensitive to the water fluoride concentration as compared with overall fractures, because the number of hip fractures in the present study is relatively small.” And they did conclude that “our results on hip fractures support previous findings that fluoride around 1 ppm in drinking water does not increase the risk of hipfracture.”

This diagram by Ethan Seigel (which I reproduced in an article earlier this year (see Getting a grip on the science behind claims about fluoridation) was clearly taking on board Li et al’s work – when perhaps it should not have been so specific.

But of course the issue of hip fractures does not rest with the work of Li et al alone. I wrote about this specifically in Fluoridation: the hip fracture deception  where I also mentioned the recent paper of Näsman et al (2013) “Estimated Drinking Water Fluoride Exposure and Risk of Hip Fracture: A Cohort Study showing no significant correlation of hip fractures with fluoride in drinking water at the optimum concentrations.


Delivery systems: It seems I must respond to Paul’s suggestion of “an alternative delivery system for fluoridated water” – selling fluoridated bottled water. I guess that already happens in many places but I did not take his suggestion  seriously because he is offering it as a substitute for already existing social health policies. That is not my area of expertise but I can understand how fluoridated water and fluoridated salt are effective as social policies for overcoming problems where the natural fluoride levels are deficient. Surely bottled water in the corner of a “supermarket, pharmacy or clinic” hardly measures up as a social health policy? Fluoridated salt seems to me to be a more credible alternative to water fluoridation.

Having said that, bottled water is culturally preferred in some countries and is attractive to some age groups in others. There are suggestions, therefore, that fluoridation of bottled water should be encouraged. New Zealand and Australia recently brought in regulations allowing this.

Inference from high concentrations: Paul has objected to my criticism that he often relies on extrapolation from laboratory or epidemiological  studies where higher than optimum fluoride concentrations were used.  He responded by discussing Xiang et al (2003) and argued that some of  the studies covered by Choi et al  (2012) did include lower concentrations.

However, there is still a tendency to then fall back on all the studies to give extra weight to his assertions, rather than just rely on the low concentration studies. I think the image below prepared by fellow New Zealander Andrew Sparrow helps put this issue into context. High fluoride cases in Choi et al (2012) were almost all completely out of the zone for optimum fluoridation of drinking water.

Chinese IQ

Appeal to authority with declarations: This tactic is used a lot by anti-fluoride activists. The poster below is a recent example from Fluoride Free NZ. The inclusion of a citation gives it some authority – but can anyone find that paper? No one at Fluoride free could – yet they were promoting a claim using the citation!

The Journal of Dental Medicine is now defunct and I could find no abstracts or full text on the internet. However, I did find a description at http://slweb.org – a well-known anti-fluoride activist site. This claimed adverse reactions, affecting “the dermatologic, gastro-intestinal and neurological systems,” to fluoride in 1% of the group studied!  I would have liked to check out the statistical analysis used in the study as this seems a very small response. Was 1% significantly different to zero in this study?

What the hell – Fluoride Free NZ doesn’t care. They went ahead with a poster and its promotion anyway. As a political activist group they are concerned more with moulding public opinion than the facts.

Paul might argue this case is a diversion he is not responsible for. But my point is that activists do this sort of thing all the time. And Paul is no different with the way he quotes from the NRC (2006) report in his section “7. What other authorities are saying about fluoride as a neurotoxicant.”

He quotes phrases like:

  • “the results appears significant enough to warrant additional research on the effects of fluoride on intelligence.”
  • “These changes have a bearing on the possibility that fluorides act to increase the risk”
  • “More research is needed to clarify fluoride’s biochemical effects onthe brain.”
  • “studies of populations exposed to different concentrations of fluoride in drinking water should include “
  • “Studies of populations exposed to different concentrations of fluoride should be undertaken”
  • “Consideration should be given to assessing.”

The point is one can agree with all these suggestions for ongoing and future research and still accept the current assessment that fluoridation is safe. Just because there is a logical possibility of a suggested danger does not, in itself, make that danger real.

This ongoing research is happening and health authorities do monitor current research findings. In New Zealand the Ministry of Health set up  the National Fluoride Information Service to do this specific job and it regularly reports current research findings. Similarly, a report from the NZ Parliamentary health committee just the other day recommended:

“the Government work with the Ministry of Health to ensure that the addition of fluoride to the drinking water supply is backed by strong scientific evidence and that ongoing monitoring of the scientific evidence is undertaken by, or for, the Ministry of Health, and that the Director-General of Health is required to report periodically to the Minister of Health on the status of the evidence and coverage of community water fluoridation.” (see From dental neglect to child abuse?).

It is irresponsible to use such urgings to continue research as some sort of proof that there are problems sufficiently big enough to warrant abandoning a social health policy known to help people. Or to call that social health policy “reckless,” as Paul does.

Paul Connett does the same thing with the paper by Xiang et al (2003) and other Chinese work in the area of IQ. He acknowledges himself that “there are weaknesses in many of these IQ studies.” These weakness and the speculative nature of his conclusions do not stop him from seriously claiming that there is a very low limit of sensitivity to fluoride effects on IQ. I repeat my question from my last article about the huge variability in the data and how the hell one can place any confidence on the result drawn from Xiang’s figure.

“Yet Paul uses Xiang’s paper to authoritatively claim it had “found a threshold at 1.9 ppm for this effect.” (What effect he refers to is unclear.) How reliable is that figure of 1.9 ppm (actually 1.85 or 2.32 ppm F in the paper) –  considering the huge variation in the data points of the Figure 1? (Unfortunately the paper is not a lot of use in explaining that figure – reviewers should have paid more attention.)”

The final request: Paul wants me “to list the primary studies that you have read which most convinced you that fluoridation is both safe for the bottle-fed baby and for the adult over lifelong exposure.” In thinking about this I have concluded it is a strange request because I don’t think creative scientists think that mechanically.

My concepts and ideas derive from multiple sources – I never put my eggs all in one basket as it were. I can find I am impressed by something in a paper which also has something which doesn’t impress me. Consequently I take what I can from wherever I can and try to critically  understand what I read.

It’s a bit like that with people. You have to accept them warts and all and avoid the immaturity of placing anyone on a pedestal – a sure way to later find they have feet of clay.

So unfortunately I cannot satisfy Paul’s request. He will have to deal with the actual arguments I put forward.

As for the issue of bottle-fed babies – I am sure this will come up at some stage. It already has in the comments discussion.

Anyone wanting to follow the debate and/or check back over previous articles in the debate can find the list of articles at Fluoride Debate.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page

Word of wisdom, and otherwise

Dara O’Briain and Frankie Boyle on religion and creationism

The comedian Dara O’Briain is a real gem. I was pleased to see him mentioned in this weeks NZ Listener – with some of his great sayings. How is this for words of wisdom about science:

Dara Ó Briain

“Science knows it doesn’t know everything; otherwise it’d stop. But just because science doesn’t know everything doesn’t mean you can fill in the gaps with whatever fairy tale most appeals to you.” NZ Listener issue 3835

Now just for contrast – here is something from a local leader of an anti-fluoridation group:

Mary Byrne

“Why would you rely on the so-called experts when they have already been proved to be wrong? and if you rely on the experts then what are you promoting? just someone else’s views, what is the point in that. Plus that sounds like religion to me.” Facebook comment.

Funny thing about these people who dislike science so much – they are always cherry picking a little bit of science, removing the context and qualifications and then presenting it as their alternative. As Dara would say – their “fairy tale.”