Category Archives: Health and Medicine

Paper claiming water fluoridation linked to hypothyroidism slammed by experts

“As epidemiological evidence goes, this is about as weak as it gets.”

Author Stephen Peckham – former chairperson of activist group “Hampshire against fluoridation”

That is the comment by Prof David Coggon, Professor of Occupational and Environmental Medicine, University of Southampton, on a new paper claiming hyporthyroidism is linked to water fluoridation. Published yesterday in the peer-reviewed Journal of Epidemiology & Community Health, the paper is:

Peckham, S., Lowery, D., & Spencer, S. (2015). Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water. J Epidemiol Community Health, 1–6.

Prof Coggan goes on to say:

“Essentially the researchers have shown that after limited adjustment for demographic differences, there are somewhat higher rates of hypothyroidism (which can result from a number of different diseases) in four areas of England that have higher concentrations of fluoride in drinking water.   It is quite possible that the observed association is a consequence of other ways in which the areas with higher fluoride differ from the rest of the country.  There are substantially more rigorous epidemiological methods by which the research team could have tested their idea”

Having read the paper I think that about sums it up.

Critical role of iodine.

The authors acknowledge that iodine plays a key role in thyroid status but they did nothing to include dietary intake or deficiency in their statistical model. It is just not good enough to declare “it is unlikely that there are significant differences [in dietary iodine intake] between people, living in fluoridated and non-fluoridated areas.”

They did include data for the proportion of people over 40 and the proportion of females because they recognised age and gender influence the incidence of hyperthyroidism. So why not include dietary iodine which is recognised as the main factor? And they are arguing that fluoride potentially acts as an iodine inhibitor, making the data for iodine even more important. Perhaps this data was not so easy to find – but did they look very hard?

Correlation is not causation

This cannot be repeated often enough. Trouble is that almost anyone can get hold of data these days and force it through a statistical package. And if they have a bias to confirm, and are willing to select their data and avoid confounders, they might get lucky.

This seems to be the case here as the senior author is a well-known anti-fluoride campaigner in the UK.* This is outside his specialty (health policy, not epidemiology).

Fluoridation data is readily available for cities and regions but it can easily be a proxy for more meaningful information like the size of towns (smaller towns usually don’t have artificially fluoridated water) or rural/urban distinctions. Cultural and ethnic factors may also be reflected in fluoridation data.

In this case, Peckham et al., (2015) simply correlated the incidence of hypothyroidism reported by individual medical practices against drinking water fluoride concentrations reported by local bodies in the region. There was no attempt to match data at the individual level. And there was no attempt to include dietary iodine intake as a factor – despite its key importance.

The size of the effect

The prevalence of hypothyroidism in the data they used is relatively low  – 3.2% with a standard deviation of 1.1%. The authors argue their results would mean that fluoridation would increase this small number by a small amount (about 30%).

Given the tentative nature and unreliability of their conclusions – if only because they did not consider dietary iodine as a factor – their recommendation should be taken with a grain of salt (preferably iodised). They recommend:

“To minimise the risk of increasing the prevalence of hypothyroidism, it is important, therefore, to limit fluoride ingestion from all sources.”

Sensible health authorities will balance the low incidence of hypothyroidism and the small effect Peckham et al (2015) claim, based on their unsatisfactory analyses, against the fact of the beneficial role that fluoride plays in the oral health of most people throughout their lives

Obviously authorities are no going to change their views as a result of this paper. Of course there will be special pleading by those opposed to fluoridation. They will argue that despite the problems with this paper the questions of fluoride as a factor in hyperthyroidism should be research further. Of course it should – scientific conclusions are always open to being altered by new evidence. But future research must be of a better quality than this. As a Prof Coggan says:

“There are substantially more rigorous epidemiological methods by which the research team could have tested their idea”

Stephen Peckham is a well-known anti-fluoride activist

I discussed Stephen Peckham in a earlier article Peer review, shonky journals and misrepresenting fluoride science. This deals with a previous paper of his and the journal he published it in.

That paper was a collection of the usual anti-fluoride arguments – based in citations without any original work. It was published in a shonky journal known to have poor peer review standards.

The current paper is in a reputable journal and does include some original work – although it is basically a statistical analysis of readily available data. No effort seems to have been made to include data for dietary iodine intake which I would think is a basic need for such a study. I am personally surprised the reviewers used by this journal did not seriously question the paper’s publication for that reason alone. I guess this reflects the imperfect and human nature of peer review even in good science journals.

At least with the current paper Stephen Peckham has declared  a conflict of interest involving his activity opposing water fluoridation – this did not happen with his earlier paper.

I expect this new paper will become another weapon in the anti-fluoridation artist armoury. It will be cited and presented as absolute proof that fluoridation is bad for our thyroids. Claims will be made that a leading scientific journal and university officially claim this! Harvard University and The Lancet all over again.

But sensible readers should never take such claims at face value. Just because a paper is published in a reputable peer-reviewed journal does not make it gospel truth. Whatever the source, such papers need to be considered intelligently and critically.

This paper does not live up to the claims the anti-fluoride propagandists will make about it.

See also:

Flawed study overstates link between fluoride and ill health: experts
Tournage de la scène «Fluoration de l’eau», prise 2793… (Shooting the scene “Water fluoridation,” taken in 2793)

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NZ Fluoridation review – Response to Micklen

I welcome open and transparent discussion here so am thankful to Dr Micklen for his response (see NZ Fluoridation review – HS Micklen responds to critique). Unfortunately he is the only author or “peer-reviewer” of Fluoride Free NZ’s report criticising the NZ Fluoridation review to accept my offer of a right of reply to my critiques.

A pity, as if any of them think I have got things wrong, and they can support this with evidence, I certainly want to know about it.

There are three aspects to Dr Micklen’s reply – dental fluorsis chronic kidney disease and his critique of my letter in the journal Neurotoxicology and Teratology –   Perrott (2015). I will deal with these separately.

Dental fluorosis

I appreciate Dr Micklen is unhappy about my criticisms of his article, and my suggestion his comments of dental fluorosis were muddled. I may have been a bit harsh but he has still not responded to my specific criticism that he:

“unfairly attributes the more severe forms [of dental fluorosis] to community water fluoridation (CWF). Consequently he calculates a cost of dental treatment which is wrong.”

The key problem is that Micklen is assuming that all the  medium and severe dental fluorosis can be attributed to CWF, whereas none of it can.

Briefly reviewing the argument – the figure below is from the NZ Ministry of Health’s Our Oral Health – the same source Micklen used.

My comment on the relevance of the different grades of dental fluorosis was:

“Moderate and severe grades of dental fluorosis are common in areas where fluorosis is endemic, but relatively rare where CWF is used. Occurrences in the latter case, despite the low concentrations of fluoride in treated drinking water, will have other causes – high natural levels in well water, industrial pollution, excessive consumption of toothpaste, etc.”

The important factor is that severe and moderate forms of dental fluorosis are not caused by CWF.

CWF can contribute to mild and very mild forms of dental fluorosis but because these are usually judged positively they certainly don’t need expensive veneers – my dentist colleagues advise simple microabrasion usually works.

So Micklen was wrong to suggest the cost of cost of veneers (up to $1750 per tooth) should be attributed to CWF because such costs would be encountered in non-fluoridated areas as well.

(In fact, if Micklen had calculated costs for such treatment in non-fluoridated areas using the “Oral Health” data in the literal way he did for the fluoridated areas,  he would have found costs to be higher than in non-fluoridated areas! Certainly doesnt’ support his claim but a meaningless result because of the small numbers and large variability).

Chronic kidney disease

Micklen accuses me of  using “a piece of grammatical legerdemain to pretend that I [Micklen] called for CKD sufferers to be warned to avoid tap water, which I did not.”

Granted he left himself a way out by actually writing:

“I suspect that most opponents of fluoridation would call for CKD sufferers to be warned to avoid tap water. Possibly the NZ health authorities have done so.”

OK, so its not a direct personal recommendation (perhaps he doesn’t belong to the group of “most opponents of fluoridation”) but a reader could be excused for getting that message and in this context it comes across as “dog whistling.”

However I will accept his assurance now that:

” In fact, I am inclined to agree with him [me] that that might be extreme in the present state of knowledge.”

As for questions like: “Does further research on the topic receive any funding priority, for example?” – well this is a round about way of giving the message that it doesn’t. Perhaps he should actually check that out and give some evidence instead of making an unwarranted implication.

This tactic of posing unfounded questions to convey an unwarranted message is typical of the approach Micklen and Connett take in their book The Case against Fluoride. I criticised this tactic in my exchange with Paul Connett (see Fluoride Debate).

I reject Micklen’s suggestion that:

“Perhaps it would be embarrassing, too, for a government to insist on putting fluoride in the water and then advise a substantial number of people not to drink it – or so one might think.”

That is silly – it is like a conspiracy theory. Why would genuine health authorities refuse to give warnings to a small group of people who might be put at risk from a social health policy that is beneficial to the vast majority? Surely they are used to such situations.

I also think he is waxing lyrical with the word “substantial!” The numbers involved would be very small, if any, and such a group would already be advised about a number of risks to them because of their condition and treatments.

Micklen also lets his ideological position take over  by drawing the implication from my article that I am saying CWF is “effective and safe – for some.” Far from it. Surely I am saying it is effective and safe for the vast majority (which is what we can expect from a social health policy) and simply recommending (as in all such policies) that the small group of people, if any, who might be at risk should use alternatives.

I am actually saying that CWF is effective and safe for at least  the vast majority and that claims to the contrary should be backed up with evidence which should be considered critically

Severe dental fluorosis and cognitive deficits

I thank Dr Micklen for his comments on my letter in the journal Neurotoxicology and Teratology – (Perrott 2015). I am pleased he accepts the hypothesis that severe dental fluorosis could explain observations of cognitive deficits is worth considering and  he agreed with the other reviewers the letter was worth publishing.

Influence of age

I take his point that the poor appearance of teeth may not influence young children (ages 6-8 as in the small the group Choi et al, (2015) studied). However, this is pure speculation on his part and is surely a detail. A detail that should be considered in any planned research incorporating this hypothesis, but not in itself a reason for rejecting the hypothesis out of hand – surely?

Unless, of course, he can give evidence to support his suggestion. I notice that he does not support the idea with any citations so suspect the idea is more one of straw-clutching  than a serious suggestion.

Actually most, but not all, of the citation I used did indeed refer to work with older children. Some were review papers and did not limit their review to any age group. Aguilar-Díaz, et al., (2011) considered children from 8 – 10 years old, Do and Spencer, (2007) studied 8-12 year olds and Abanto et al., (2012) 6-14 year old children. Chikte (2001) studied three groups: 6, 12, 15 year olds.

However, I found a quick literature search showed reports of negative effects of oral defects like tooth decay on the child’s quality of life. Kramer et al., (2013) reported this for ages 2 – 5, Scarpelli et al., (2013) for 5 year olds and Cunnion et al., (2010) for 2 – 8 year olds.

So, I suggest on the available evidence the negative influence of severe dental fluorosis on quality of life (and possibly cognitive deficits) is likely to occur even in younger children who have not “reached an age to be self-conscious about their appearance.”

I don’t think young children are as immune to social attitudes and personal appearance as Dr Micklen suggests.

Does effect depend on how common dental fluorosis is? 

Dr Micklen suggests that:

“Since fluorosis was common in the community [the children studied by Choi el., 2015], having the condition would not appear abnormal.”

Again I think he is indulging in straw-clutching, or special pleading.


Clearly medium and severe dental fluorosis is far more common in this Chinese group than in countries like New Zealand which use CWF. In the graph below I compare their data with that for New Zealand and USA. Incidentally, this figure shows why the data from Choi et al., (2012, 2015) should not be used as an argument against CWF – yet that is what Micklen did in his original article.


But this does not mean that those children with more severe forms will not stand out against the children with less severe forms. There is always a range of appearances of such defects in a group of children. Some will obviously suffer more than others because of their appearance.

If Choi et al., do continue to include detailed analysis of dental fluorosis in their future work on this issue then it will be possible to compare cognitive deficit measurements with dental fluorosis indices in a larger group. Such data will be interesting.

However, discussion of details like this is premature. My letter simply raised to idea as an alternative worth considering and encouraged the group to continue including detailed dental fluorosis measurements in future work. I was also concerned that they were not being sufficiently open-minded in their choice of a working hypothesis. I concluded my letter with:

Researchers need to be careful not to limit their possible hypotheses or research approaches. Unfortunately Choi et al. (2014) appear to be doing just this with their plans for a larger scale study targeted only at “fluoride’s developmental neurotoxicity.”

Unfortunately none of this group have yet responded to my letter.

So, again, I thank Dr Micklen for his feedback on that letter – and his acceptance of the right-of-reply to my article critiquing the FFNZ report.

See also:


Abanto, J., Carvalho, T. S., Bönecker, M., Ortega, A. O., Ciamponi, A. L., & Raggio, D. P. (2012). Parental reports of the oral health-related quality of life of children with cerebral palsy. BMC Oral Health, 12, 15. doi:10.1186/1472-6831-12-15

Aguilar-Díaz, F. C., Irigoyen-Camacho, M. E., & Borges-Yáñez, S. A. (2011). Oral-health-related quality of life in schoolchildren in an endemic fluorosis area of Mexico. Quality of Life Research : An International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation, 20(10), 1699–706.

Chikte, U. M., Louw, A. J., & Stander, I. (2001). Perceptions of fluorosis in northern Cape communities. SADJ : Journal of the South African Dental Association = Tydskrif van Die Suid-Afrikaanse Tandheelkundige Vereniging, 56(11), 528–32.

Choi, A. L., Sun, G., Zhang, Y., & Grandjean, P. (2012). Developmental fluoride neurotoxicity: A systematic review and meta-analysis. Environmental Health Perspectives, 120(10), 1362–1368.

Choi, A. L., Zhang, Y., Sun, G., Bellinger, D., Wang, K., Yang, X. J., … Grandjean, P. (2015). Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study. Neurotoxicology and Teratology, 47, 96–101.

Cunnion, D. T., Spiro, A., Jones, J. a, Rich, S. E., Papageorgiou, C. P., Tate, A., … Garcia, R. I. (2010). Pediatric oral health-related quality of life improvement after treatment of early childhood caries: a prospective multisite study. Journal of Dentistry for Children, 77, 4–11.

Do, L. G., & Spencer, A. (2007). Oral Health-Related Quality of Life of Children by Dental Caries and Fluorosis Experience. Journal of Public Health Dentistry, 67(3), 132–139.

Kramer, P. F., Feldens, C. A., Ferreira, S. H., Bervian, J., Rodrigues, P. H., & Peres, M. A. (2013). Exploring the impact of oral diseases and disorders on quality of life of preschool children. Community Dentistry and Oral Epidemiology, 41(4), 327–35.

NZ Ministry of Health. (2010). Our Oral Health Key findings of the 2009 New Zealand Oral Health Survey.

Perrott, K. W. (2015). Severe dental fluorosis and cognitive deficits. Neurotoxicology and Teratology.

Scarpelli, A. C., Paiva, S. M., Viegas, C. M., Carvalho, A. C., Ferreira, F. M., & Pordeus, I. A. (2013). Oral health-related quality of life among Brazilian preschool children. Community Dentistry and Oral Epidemiology, 41(4), 336–44.

NZ Fluoridation review – HS Micklen responds to critique

I have posted several articles in a series critiquing contributions to the Fluoride Free NZ report Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report which is aimed at discrediting the recent review Health Effects of Water Fluoridation: a Review of the Scientific Evidence produced by the Royal Society of NZ together with the Office of the Prime Minister’s Chief Science Advisor. The articles in this series are collected into a pdf document which can be downloads from Download report analysing anti-fluoride attacks on NZ Fluoridation Review.

In an attempt to encourage a discussion on the fluoridation review and the FFNZ report I offered all the authors and “peer-reviewers” of the FFNZ report the right of reply to my critiques. So far Dr H. S. Micklen (whose article I critiqued in Fluoride Free NZ report disingenuous – conclusion), is the only one to take up this offer.

Here is his reply. 

I thank Dr Perrott for reproducing my notes on the NZ Fluoridation Review and appreciate his comments. My appreciation would be warmer had he spent less time using his imagination and paid more attention to what I actually wrote.  He has me bustling around, agenda in hand, clutching at straws here, raising bogeys there, scaremongering, relying on this, calling for that, and getting confused about different grades of fluorosis (as if..,). All nonsense.  If I “distort the science” as Perrott’s headline proclaims, he does a great job of distorting the distortion.

Most of my short piece merely commented on a few places where, in my opinion, the NZ report failed – through error, omission or incompetence – to reach proper standards of objectivity and impartiality and exhibited ill-founded complacency. Since the NZ report was highly biased in favour of fluoridation, any criticisms of it are likely to have an anti-F flavour. Too bad; I was dealing with the report’s view of the science, not pushing my own. I avoided speculating on the outcome of issues that I consider unresolved, dental fluorosis (where Perrott makes nonsense of what I wrote) being the only exception.

Most of these issues have been argued over ad nauseam and I shall not try to unscramble Perrott’s lucubrations. The question of chronic kidney disease and its possible cardiovascular consequences is perhaps an exception. I gave credit to the Review for discussing the paper by Martin-Pardillos. Agreeing with the Review’s opinion that the results needed to be confirmed, I remarked “The interesting question is, what should happen meanwhile?” That is not a rhetorical question. What does, or should, happen when an alarm bell sounds over a long-established procedure? Does further research on the topic receive any funding priority, for example?  Perrott uses a piece of grammatical legerdemain to pretend that I called for CKD sufferers to be warned to avoid tap water, which I did not. In fact, I am inclined to agree with him that that might be extreme in the present state of knowledge. Perhaps it would be embarrassing, too, for a government to insist on putting fluoride in the water and then advise a substantial number of people not to drink it – or so one might think. But Perrott concludes “Any patients who are particularly worried can then take steps like using filtered water for their own peace of mind. This seems more appropriate than denying the rest of the population access to a simple, effective and safe (for them at least) social health policy like CWF.”  So that’s all right then, thanks to the patients, whom Perrott doubtless consulted, being willing to promote the alleged greater good. He has pricked a hole in the old mantra, though: “effective and safe – for some”.

Perrott asked for my feedback on his idea about the possible effect of dental fluorosis on IQ.  Since then his paper has appeared online as a short article in Neurotoxicology and Teratology. Perhaps the best thing I can do at this stage is pretend that it had arrived on my desk for peer review. I would have commented as follows.

“This communication refers to a recent paper by Choi et al (2014) that reports certain cognitive defects in young children affected by moderate-severe dental fluorosis. Choi et al suggest that this is due to an adverse effect of fluoride on the developing brain. The present author proposes an alternative explanation, namely that fluorosis itself, and the stress of living with it, can affect learning and general quality of life and result in poor performance in certain types of cognitive test. This appears to be a novel idea and, as such, is suitable in principle for publication as a short communication. There is, however, a fundamental question that the author should be invited to address and clarify with a view to possible resubmission.

“The paper is somewhat discursive and lacking in focus and in the course of it the author seems to lose track of what age group he is talking about. Surprisingly, he does not mention the age of Choi’s (2014) subjects, which averaged 7 years  (range 6-8). When he finally presents evidence that moderate-severe fluorosis is aesthetically displeasing and likely to impair quality of life, all of it relates to older children, mainly teenagers, who have reached an age to be self-conscious about their appearance and have been living with fluorosis for several years. In contrast, 16% of Choi’s (2014) subjects had no erupted permanent teeth at all and in the remainder eruption of the first permanent teeth would have been very recent. Since fluorosis was common in the community, having the condition would not appear abnormal. The crucial question is whether the author is proposing that the quality of life of these young children is so compromised by fluorosis as to impair their performance in cognitive tests. Apparently the answer is a tentative affirmative: It is just possible that the negative quality of life associated with oral defects like severe dental fluorosis contribute to cognitive deficits reported by Choi et al. (2012, 2014)’

“The author needs to discuss this issue in a transparent fashion so that readers can judge for themselves whether the proposal is plausible. Conversely, if he is not making such a proposal, that too should be made clear.

“The author might wish to refresh his memory of the paper by Hilsheimer and Kurko (1979), which really is of virtually no relevance to his argument.”

I hope this helps.

H S M 12 February 2015

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Did business interests interfere with Hamilton’s fluoride tribunal process?


 Source: Abuse of democratic process in Hamilton Tribunal?. (Click to enlarge).

Early results from a Waikato University research project show that around 2/3 of all the written submissions to the Hamilton City Council’s fluoride tribunal process were directly or indirectly provided by parties associated with the ‘natural health’ lobby.

This is interesting as it raises the question of links between this lobby and the anti-fluoride movement. I showed in When politicians and bureaucrats decide the science  how the submission process in this case was dominated by the anti-fluoride movement and how their misrepresentation of the science fooled the local body politicians and bureaucrats. In Who is funding anti-fluoridation High Court action? I showed how big money from the “natural” health industry was financing legal action against fluoridation.

This research is not yet complete so we look forward to further details on this relationship and on how such corporate interests and activists groups cooperate in submissions to local body councils.

The research project is “Public Integrity and Participatory Democracy: Hamilton City Council’s Water Fluoridation Decision“. Waikato University student Luke Oldfield is carrying out the work financed by the grant. He recently displayed a poster(above) to an audience of academic faculty sharing some preliminary results of his research.

Interestingly spokespeople for the anti-fluoride groups have opposed this research from the moment of the announcment of the grant (see Anti-fluoride activists unhappy about scientific research).

Something to hide, perhaps?

Thanks to Abuse of democratic process in Hamilton Tribunal? at the new Making Sense of Fluoride web page.

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Download report analysing anti-fluoride attacks on NZ Fluoridation Review


The NZ Fluoridation review, Health Effects of Water Fluoridation: a Review of the Scientific Evidence, is an authoritative and up-to-date review on water fluoridation in New Zealand. The anti-fluoridation activist organisation Fluoride Free NZ (FFNZ) attempted to discredit the review with their report Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report.

In this report, Fluoridation is Safe and Effective, I analyse the FFNZ critique and show it was written, and “peer-reviewed” by well know anti-fluoridation activists

This report analyses the three main articles in the FFNZ document showing that the critique is based on misinformation commonly promoted by anti-fluoride propagandists.

I point out a small mistake in the executive summary of the Fluoridation review and describe how it arose. The concept was explained correctly in the body of that report. The mistake, little more than a typo, has now been corrected.

Fluoridation is Safe and Effective is a slightly edited version of a number of articles posted on this blog. It is now available to download in pdf format.

I hope this report will be useful wherever Fluoride Free NZ use their own document in an attempt to discredit the NZ Fluoridation Review. If FFNZ use their misleading document in their campaigns to local body councils, or in presentations to the media and public meetings this report can provide the material which debunks their claims.

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Social health policies, freedom of choice and responsibility

Social health policies inevitably raise the issue of the individual’s freedom of choice. While debates around these policies often concentrate on questions of fact, scientific consensus and reliability of evidence, these tend to be surrogates for the underlying values issues. To what extent should I sacrifice my freedom of choice, or my freedom of choice to decide for my children, for the good health of the community? And what if my freedom of choice violates the freedom of choice for others?

hall-offit-fullPaul Offit discussed these issues in a recent Point of Inquiry podcast – Paul Offit, MD, on Measles in the Magic Kingdom and the Anti-Vaccine Movement. He is a Professor in the Division of Infectious Diseases and the Director of the Vaccine Education Center at the Children Hospital of Philadelphia. Offit is the author of the book Do You Believe in Magic?: The Sense and Nonsense of Alternative Medicine.

He basically talks about the spread of measles throughout California and neighboring states because of a source of infection at Disneyland. Although measles were eliminated in the U.S. by 2000, the misinformation of the anti-vaccine movement has caused a return of a full-fledged outbreak.

Levels of responsibility and consequences

Paul makes the comparison of opposition to vaccination with opposition to blood transfusion.

1: Blood transfusions. A person my refuse to accept treatment involving blood transfusion because of their personal religious beliefs. More questionably they may refuse on behalf of their children. However, the consequences are limited to the person or her child. The decision does not harm the community at large.

2: Vaccinations. A person may refuse a measles vaccination for themselves or their children. But in this case the consequences are not personal – they affect the whole of society. By lowering the degree of immunisation in the community they threaten the lives of others – particularly the most vulnerable, children.

In these two cases the person has refused an intervention, a medical treatment or vaccination, which could be seen to violate their freedom of choice – or even to violate their body. In the first case the consequences are personal, limited to the person who made the wrong decision. But in the second case the consequences are social. An personal wrong decision has taken away the freedom of choice, the health and in some cases the lives, of others in society.

A bit like the personal decision to drive on the wrong side of the road. Society has taken away a small personal freedom of choice in our road rules to protect the lives of all of us.

3: Fluoridation. Social health policies like community fluoridation of water, salt, milk, etc., are recognised as being safe, beneficial and cost-effective. But they are opposed by a vocal minority. Activists will passionately promote the freedom of choice argument and, considering they don’t have the scientific evidence on their side this is often seen as their strongest argument. After all, it is values-based and therefore can’t be tested and rejected by evidence.

But, this third case is different to the other 2.

  • The act of fluoridation or not is social, taken by society as a whole or their representatives. An person may contribute to the decision but cannot decide the issue by a personal action as they can with vaccinations or blood transfusions. Although individual political action, or dissemination of information or misinformation, may influence that social decision – and hence the social consequences.
  • Fluoridation does not involve an intervention or treatment, medical or otherwise. No one is forced to drink fluoridated water or milk, or to consume fluoridated salt. The freedom of choice argument is invalid here because there are always alternatives.

Despite actively promoting the freedom of choice argument even the NZ anti-fluoride activist Fluoride Free NZ provides information on these atlernatives. They list alternative water sources, distillation, ion exchange filters and reverse osmosis. Most of these choices are cheap and available.

So what is driving anti-fluoridation propagandists?

Unlike opponents to blood transfusion they cannot argue freedom of choice to refuse an intervention on religious grounds. There is no intervention. The only personal imposition is that they may wish to buy a water filter (many already have these) or buy water from a different source.

Again, unlike opponents of vaccination they cannot argue freedom of choice to refuse an intervention even on grounds of personal belief – because there is no personal intervention.

Given the lack of any forced or personal intervention I am forced to conclude the freedom of choice issue that concerns the anti-fluoride activists is their freedom of choice to decide the oral health quality of other members of their community. And given the health and scientific expert consensus on the issue they are really arguing for their freedom of choice to decide the oral health of others on the grounds of their own minority personal beliefs or convictions.

In last year’s High Court judgement on the question of fluoridation in South Tarinaki, Justice Hansen wrote:

“Provided it does not have consequences for public health a person has the right to make even the poorest decisions in respect of their own health. But where the state, either directly or through local government, employs public health interventions, the right is not engaged. Were it otherwise, the individual’s right to refuse would become the individual’s right to decide outcomes for others. It would give any person a right of veto over public health measures which it is not only the right but often the responsibility of local authorities to deliver.”

The freedom of choice the anti-fluoride activists are promoting is their freedom of choice to decide health outcomes for others – not themselves.

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tin foilCredit: The Skeptics’ Guide to the Universe

This cartoon reminded me of some of the local campaigners against fluoridation. They almost all are either strongly connected to the “natural” health movement and its businesses, or, because of their beliefs, are customers of that industry. Yet they often argue that genuine scientific and health experts are in the pay of “big pharma” or similar businesses and are acting as “shills” for industry! That is plain hypocrisy. Similar articles

Severe dental fluorosis and cognitive deficits – now peer reviewed

Last May I raised the possibility that the much touted relationship of small IQ declines for children living in areas with naturally high fluoride in drinking water could be associated with severe dental fluorosis and not a chemical neurotoxicant (see Confirmation blindness on the fluoride-IQ issue). In November I repeated this argument because the recently published work by Choi et al (2015) provided evidence of a statistically significant relationship of cognitive deficits to severe dental fluorosis for Chinese children living in high fluoride areas  (see Severe dental fluorosis the real cause of IQ deficits?).
I am pleased to report the journal Neurotoxicology and Teratology (which published the Choi et al., 2015 paper) have now accepted a peer-reviewed letter to the Editor from me on the subject:

Perrott, K. W. (2015). Severe dental fluorosis and cognitive deficits. Neurotoxicology and Teratology.

Don’t limit possible hypotheses

My letter warns:

“cognitive deficits could have many causes or influences – genetic, environmental and/or social. Researchers need to be careful not to limit their possible hypotheses or research approaches. Unfortunately Choi et al. (2015) appear to be doing just this with their plans for a larger scale study targeted only at “fluoride’s developmental neurotoxicity.””

It points out:

Choi et al. (2012) did highlight the need for further research. Broadbent et al. (2014) showed no effect of fluoride on IQ at the optimum drinking water concentrations used in CWF [community water fluoridation]. However, most of the reports reviewed by Choi et al. (2012) considered data from areas of endemic fluorosis where drinking water fluoride concentrations are higher.”

“Choi et al. (2015) did not find a statistically significant association of drinking water fluoride concentration with any of the neuropsychological measurements. But they did find one for moderate and severe dental fluorosis with the WISC-R digit span subtest.”

This suggests a possible hypothesis involving the effects of negative physical appearance and not a chemical neurotxocant:

“Emotional problems in children have been related to physical anomalies, including obvious oral health problems like severe tooth decay (Hilsheimer and Kurko, 1979). Cognitive deficits can sometimes be related to emotional problems and subsequent learning and behavior problems. Quality of life- particularly oral health related quality of life is negatively related to tooth decay and severe dental fluorosis. It is possible that negative oral health quality of life feelings in children could induce learning and behavior difficulties which are reflected in neuropsychological measurements.”

Difference between areas of endemic fluorosis and CWF

This hypothesis is applicable to children in areas of endemic fluorosis but is not relevant to areas where CWF is used:

“Sixty percent of the children in the Choi et al. (2015) pilot study had dental fluorosis graded as moderate or severe. This likely reflects the endemic fluorosis of the study area. Only a few percent of individuals in areas exposed to the optimum levels of drinking water fluoride used in CWF have dental fluorosis that severe. For example, a recent oral health survey in New Zealand found 2% of individual had moderate dental fluorosis and 0% had severe dental fluorosis (Ministry of Health, 2010). Similarly a US survey found only 2% of individuals exhibited moderate dental fluorosis and less the 1% severe dental fluorosis (Beltrán-Aguilar et al., 2010).”

“Tooth decay and other oral defects negatively impact a child’s quality of life as assessed by children and parents (Barbosa and Gavião, 2008; Nurelhuda et al., 2010; de Castro et al., 2011; Aguilar-Díaz et al., 2011; Biazevic et al., 2008; Abanto et al., 2012Krisdapong et al., 2012; Bönecker et al., 2012; Locker, 2007). Quality of life impacts have also been found for dental fluorosis, but there is a marked difference in physical appearance and quality of life assessments for children with moderate/severe dental fluorosis compared with those having none/questionable or very mild/mild forms.

The physical appearance of moderate and severe forms of dental fluorosis is generally considered undesirable so we could expect these forms to be associated with poor quality of life and this appears to be the case (Chankanka et al., 2010; Do and Spencer, 2007; Chikte et al., 2001). In contrast, most studies report no effect or a positive effect of questionable, very mild and mild forms of dental fluorosis on quality of life (Do and Spencer, 2007; Chankanka et al., 2010; Peres et al., 2009; Biazevic et al., 2008; Büchel et al., 2011; Michel-Crosato et al., 2005).

Given the different patterns of dental fluorosis severity in areas of endemic fluorosis and areas where CWF is practiced and fluoride intakes are likely to be optimal it seems reasonable to expect a difference in ways fluoride intake influences health-related quality of life and possibly cognitive factors.”

My purpose in this letter was to argue that other mechanisms besides chemical neurotoxicity should be considered in these studies. I hope researchers take this on board and look forward to the response of Choi and her co-workers to this suggestion.

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Those evil chemicals

Looks like community water fluoridation has become an issue in the upcoming by-election for the New Plymouth City Council. All the usual arguments are being promoted but the one I find most grating is the rejection of fluoride because “it is a chemical.”

So I loved this comment:

“I vote that anyone who doesn’t want the chemicals added to their water has all the chemicals removed from their bodies… they can keep what’s left.”


body elements

“Internet and social media misinform thousands daily”

A recent analysis of the internet and social media illustrates the up-hill battle science and health professionals, and pro-science lay people, often face with misinformation and outright distortion of science. The authors show the problem for the case of community water fluoridation and concluded:

“The Internet and social media are misinforming thousands of people daily about the safety, health, and economic benefits of community water fluoridation. The leading anti-fluoridation website had 5 to 60 times more traffic than the two leading profluoridation health organizations. All Groups and Pages analyzed on Facebook were against fluoridation, while 99 percent of the videos searched on YouTube and the majority (70 percent) of fluoridation tweets on Twitter were anti-CWF fluoridation.”

This study drew important lessons for science and health professions:

Pro-fluoridation organizations need to have a better presence on the Internet and utilize social media to educate the American people about the facts on fluoridation. Individual dental and health practitioners need to educate their patients about fluoridation, so their patients will not be easily misguided by misinformation on the Internet and social media.

And, of course, these lessons are just as applicable to New Zealand.

The study is reported in the paper:

Mertz & Allukian (2014). Community Water Fluoridation on the Internet and Social Media. Journal of the Massachusetts Dental Society, 63(2), 32–36. (You can download a pdf here.)

They monitored website traffic for major fluoridation websites from June 2011 – May 2012 and fluoridation information on Facebook on April 3, 2012. In addition they collected search data for the term “fluoridation” on Twitter for 2 periods (March 1 – 14 and April 1 – 14, 2012) and on YouTube for April 3, 2012.

The data

I illustrate some examples of the data presented in the figures and tables below.

This figure shows that the most important anti-fluoridation website, Paul Connett’s Fluoride Action Network, had far more traffic than the Wikipedia fluoridation section and the institutional web sites (which are pro-fluoridation) on fluoridation.


The situation for Facebook groups and pages was even more dire with 193 search results being “anti” while none were “pro.”


The Twitter search also showed far more anti- than pro-fluoridation tweets, although the data shows  the numbers are influenced by important articles.


Some observations

Of course this is a limited study and much more could be said about this situation, the business interests driving it and possible solutions. I list a few observations below:

1: This study is a snapshot in time. For example, Table 1 would look a little different at this time (January 2015) than it did in April 2012. There are now a number of specifically pro-fluoridation, or at least uncommitted Facebook pages and groups.

My brief search for Facebook “pages” and “groups” using the words fluoride or fluoridation showed about 8 pro-fluoridation, or neutral, pages in the first 50 results for “fluoride” and 2 for “fluoridation.” There were about 4 “pro” Facebook groups in the first 50 for either of these two search terms.

Things are improving. In New Zealand we have seen an increased activity of pro-science groups since the undemocratic decision (now reversed) of the Hamilton City Council to stop fluoridation. This was under pressure from anti-fluoride activists (nationally and internationally) and against the expressed wishes of the citizens. Similar fight-backs are happening overseas – in USA, Canada, Ireland and the UK. The progress is welcome  but more is required. Although I should note there is a tendency for anti-fluoridation activists to set up Facebook pages for many locations where there may have been suggestions of campaigns but the pages become inactive in a short while.

2: Who is financing these anti-fluoridation websites and social media activity? There is a clear connection between the “natural” health industry and anti-fluoridation organisations and activity. Paul Connett’s Fluoride Action Network is organisationally connected with Mercola’s “natural” health business (and anti-vaccination groups) through the “Health Liberty” organisation  and financial flows from Mercolla to FAN are well known. Similarly in  New Zealand the “natural” health industry, through the NZ Health trust, has financed legal action of anti-fluoridation groups (see Who is funding anti-fluoridation High Court action? and Corporate backers of anti-fluoride movement lose in NZ High Court).

3: Is there an underlying purposeful strategy behind then internet and social media anti-fluoridation activity? Definitely. I gave an example illustrating this in Anti-fluoridationist astro-turfing and media manipulation. Activist groups will create press releases pretending to be scientifically authoritative. These are picked up by the “natural” health web sites and magazines (and sometimes, if they are lucky) by the main media. They get coverage on Facebook pages and are tweeted – often automatically by internet bots and the web sites themselves. They can easily create “Twitter storms” this way and widely spread their misinformation.

Here are some typical examples that get repeated ad nauseum:

And, the misinformation cycle gets repeated. Information on Twitter gets reproduced in blog comments and included in web sites and press releases.

4: Institutional web sites are not really suitable for this sort of debate on the internet and in social media. This is partly the problem of a serious, rational or logical web presence challenging an often emotional web presence. A calm explanation of the science challenging claims appealing to preconceived prejudices and emotional needs.

Also, institutions traditionally have felt such debates are somewhat “below” them, preferring not to get into what they see as “street-fighting.” Recently I heard of a case where an anti-pseudoscience group had asked permission to use material from a professional dental site for use in a booklet. They were turned down because the association could not see why this was necessary!

This suggests that pro-science activists should consider taking the initiative, launching their own web sites, etc., and participating in these sorts of struggles, rather than relying on existing institutions. Similarly such activists should see they can play a far more active role on Facebook and Twitter than institutions can, or a willing to.


This study shows that people are in general being misinformed by social media and the internet about community water fluoridation. I suggest this is not accidental – political and business interests are actively encouraging this misinformation. In particular, the “natural” health industry plays a key role in promoting misinformation on fluoridation.

Recently things are improving a little with a fight back from pro-science groups and individuals. I suggest their activity is essential as institutional groups and media outlets are not suited for  internet and social media debates.

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