Category Archives: New Zealand

March ’15 – NZ blogs sitemeter ranking

BlogThere are now over 300 blogs on the list, although I am weeding out those which are no longer active or have removed public access to sitemeters. (Let me know if I weed out yours by mistake, or get your stats wrong).

Every month I get queries from people wanting their own blog included. I encourage and am happy to respond to queries but have prepared a list of frequently asked questions (FAQs) people can check out. Have a look at NZ Blog Rankings FAQ. This is particularly helpful to those wondering how to set up sitemeters.

Please note, the system is automatic and relies on blogs having sitemeters which allow public access to the stats.

Here are the rankings of New Zealand blogs with publicly available statistics for March 2015. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers.

Meanwhile I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

Subscribe to NZ Blog Rankings

Subscribe to NZ blog rankings by Email

Find out how to get Subscription & email updates

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Open letter to Lisa Hansen on NZ Fluoridation Review

Dear Lisa,

There are mistakes and misinterpretations of the scientific literature in your recent open letter to Sir Peter Gluckman and Sir David Skeggs. The letter also misrepresents the NZ Fluoridation Review (Eason et al., 2014) and the Fluoride Free NZ (FFNZ) report criticising that review. It gives the latter report more credibility and status than it deserves.

I am responding with an open letter of my own because I think the mistakes and misrepresentations need correction. I hope you receive my critique with the respect for the scientific openness,  criticism and healthy discussion you assert in the last paragraph of your letter. That certainly describes my approach and in that light I offer you a right of reply on my blog to this open letter.

First I consider some aspects of the way you present the NZ Fluoridation Review and the FFNZ report.

Citing the NZ Fluoridation Review

You generally cite Health Effect of water fluoridation: A review of the scientific evidence (Easton et al., 2014) as  the “Gluckman/Skegg report.” I realise you did this because your clients, and particularly the Fluoride Free NZ activist group, have adopted that terminology. It is however disrespectful to the real authors of the review. Such reports are not usually attributed to the heads of institutes or organisations.

Nature of the NZ Fluoridation Review

You unfairly compare Easton et al., (2014) to other major reviews in terms of cost, time taken, processes and the publication period reviewed. You are simply citing the activist FFNZ report which set out to discredit the NZ Fluoridation Review in any way possible.

The Fluoridation Review describes its approach in this way:

“Several previous rigorous systematic reviews were used as the basis for this analysis, and literature searches in Medline, EMBASE, the Cochrane library database, Scopus, and Web of Science were undertaken to identify subsequent studies in the peer-reviewed scientific literature. Alleged health effects from both the scientific and non-scientific literature were considered, and many original studies relating to these claims were re-analysed.” [My emphasis].

The Review’s purpose was not to duplicate the previous extensive reviews on this subject. It instead summarised them and reviewed later research. In other words the goals were simpler and less costly. (Costs were in any case determined by the local bodies which commissioned and, together with the Ministry of Health,  paid for the review.)

The FFNZ comparison is disingenuous.

The FFNZ Report.

You promote the inaccurate self-description of the FFNZ report (Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report) as “international peer reviewed.” That is the impression FFNZ attempts to convey  but it is dishonest – all the authors and “peer-reviewers” are connected with, or work for, Paul Connett’s Fluoride Action Network and similar activist organisations in the US or NZ. I illustrate some of the links in the figure below taken from the blog article The farce of a “sciency” anti-fluoride report.

I have provided an in-depth analysis and critique of the FFNZ report in a series of blog articles which are available in a single PDF document (Fluoridation is safe and effective: A critique of Fluoride Free NZ’s criticism of The NZ Fluoridation Review).

Now, the substantive issues you raise in your open letter.

Endemic fluorosis, community water fluoridation and IQ

Up front we must be clear about the situations behind the various scientific studies on the issue of fluoride and IQ.

So far, the only study  directly relevant to community water fluoridation (CWF) is that of Broadbent et al., (2014). This studied populations in the Dunedin region over a long time period. Notably you do not refer to this study, despite its extensive nature and relevance to the issue at hand. In  fact you seem unaware of the research as you claim in your letter that the “impact on IQ from water fluoridation at between 0.7 and 1 ppm” is “as yet unmeasured!”

The studies you do cite (mainly Choi et al., 2012) are from areas of higher fluoride consumption. Most of the studies were from areas of endemic fluorosis – mainly in China. This means that the findings cannot simply be transferred to areas like NZ.

Choi et al., (2012) are clear about the criteria used for choice of studies in their metareview. They say:

“We specifically targeted studies carried out in rural China that have not been widely disseminated, thus complementing the studies that have been included in previous reviews and risk assessment reports.”

And

“Opportunities for epidemiological studies depend on the existence of comparable population groups exposed to different levels of fluoride from drinking water. Such circumstances are difficult to find in many industrialized countries, because fluoride concentrations in community water are usually no higher than 1 mg/L, even when fluoride is added to water supplies as a public health measure to reduce tooth decay.”

This is why the Choi et al., (2012) meta review is not directly relevant to CWF.

Choi et al., (2012) not relevant to CWF.

I can illustrate the difference between that situations reviewed by Choi et al., (2012) and the New Zealand situation where CWF is common using dental fluorosis data from the recent paper of Choi et al., (2015),  Our Oral Health (2010) and Beltrán-aguilar & Barker (2010) (see Water fluoridation and dental fluorosis – debunking some myths).

There is very little severe or moderate dental fluorosis in NZ and USA. But it is very common in the area studied by Choi et al., (2015) which is probably typical of the areas reviewed by Choi et al., (2012) and the Indian paper you cite (Saxena et al., 2012). Unfortunately most of the studies reviewed by Choi et al., (2012) are of poor quality (see below) and do not include data for many possibly confounding factors like severe dental fluorosis, pesticide use, etc.).

So – clearly different situations.

The metareview of Choi et al (2012) was a metareview of studies from higher fluoride areas – not a metareview of studies from all areas, or studies from areas where CWF is common. Their review is not directly applicable to situations where CWF is considered, like NZ and USA.

The authors have stated this themselves:

“These results do not allow us to make any judgment regarding possible levels of risk at levels of exposure typical for water fluoridation in the U.S. On the other hand, neither can it be concluded that no risk is present.”

Note: I have suggested (Perrott 2015) that the small cognitive deficits report by the Choi et al., (2012) could be caused by severe dental fluorosis, and not directly caused by chemical toxicity. (I discuss this further below.) This is consistent with the results of Choi et al., (2015) who observed a significant relationship of cognitive deficits to severe/medium dental fluorosis but did not find a significant relationship with the fluoride concentration of the drinking water.

I believe researchers studying IQ effects in areas of endemic fluorosis should consider this hypothesis.

The “error” in the NZ Fluoridation Review

Your open letter concentrates mainly on an “error” in the NZ Fluoridation Review. This “error” was little more than a “typo,” occurred only in the executive summary (the body of the review reported the science correctly), and was corrected by the authors when brought to their attention. They also corrected at least one other error at the same time. I have discussed this in Did the Royal Society get it wrong about fluoridation?

Any publishing author is well acquainted with the problems of typos and similar errors. Despite the best proof-reading of drafts one inevitably finds some errors only after publication. (An example of Murphy’s Law, I guess.) This error has only become an issue because of the intention of activist organisations who wish to discredit the review.

It is worth noting that the Harvard University press release reporting the research concerned made exactly the same error and acknowledged and corrected it when pointed out. The current version now says:

“The average loss in IQ was reported as a standardized weighted mean difference of 0.45, which would be approximately equivalent to seven IQ points for commonly used IQ scores with a standard deviation of 15.*

** This sentence was updated on September 5, 2012.”

Yet, you, FFNZ and their associates do not criticise Harvard University!

Your mistaken description of error.

First, I will stress again that discussion of this “error” refers to the work of Choi et al., (2012) and areas where fluorosis is most likely endemic. That research does not deal with CWF or the situations where drinking water fluoride concentrations are that low.

The slide below, from a presentation made by Xiang (2014) at Paul Connett’s last conference in Washington, gives an idea of the situation in areas where these studies were made. Xiang is the author of several of the papers reviewed by Choi et al (2012) and commonly used by anti-fluoride activists in arguing against CWF.

This is clearly a different situation to New Zealand.

What did Choi et al (2012) actually report?

They report in their abstract “The standardized weighted mean difference in IQ score between exposed and reference populations was –0.45.” This is a standard deviation resulting from their analysis of 27 studies with different methods and quality of data. It is not a difference in IQ score.

This approach was necessary because the different studies reviewed had different IQ scales, different measurement methods and different levels of variation in the data. They standardised the differences by expressing them as a fraction of the standard deviation for each study. A mean value over all studies was determined, weighting the contribution from each study according to the precision of the IQ measurements.

Mistakenly, Harvard University and the NZ Review summary originally described this as an IQ score difference instead of SD. (Note – this mistake was not in the body of the NZ Fluoridation Review). In fact many readers were confused as the statistical process used by a Choi et al (2012) was not sufficiently well explained from a lay person’s viewpoint and they had to publish an extra explanation later (Choi et al., 2013).

Going from a standardised weighted mean difference value to a difference in IQ points.

Standard deviation is a function if variation in data so it is wrong to assume a value for all situations. It will be different for different sets of data.

The standardised weighted mean difference value of 0.45 has meaning because we know it represents less than half of one standard deviation so it indicates how it compares with measurement error. Many people have equated the difference of 0.45 to 7 IQ points. However, Choi et al., (2012)  did not report a difference of 7 you claim. This value came out of the explanation in Choi et al., (2013) in their response to a letter to the editor. They provided an example for a commonly used IQ scale normalised against a theoretical bell curve:

“For commonly used IQ scores with a mean of 100 and an SD of 15, 0.45 SDs is equivalent to 6.75 points (rounded to 7 points).”

This cannot simply be translated to any other IQ scale. For example these values would be inappropriate for the IQ scale used in Saxena et al., (2012)  study you refer to later in your letter.

The significance of the 0.45 standard deviation decrease in IQ points.

It is easy to throw around values of 7 and 15, as you do, but what is the significance of the result (for areas of endemic fluorosis – let’s not forget this study is not directly relevant to CWF). Choi et al., (2012) themselves warn that a decrease of 0.45 standard deviation “may seem small and may be within the measurement error of IQ testing.”

All this says is that many data sets, especially those with high variability, may not show a difference between children from high and low fluoride areas because the difference measured by Choi et al., (2012) is relatively small. In saying that I am not trying to deny any significance at all to their results. However, it is provisional and, as they say, it needs further confirmation. I think two points must be made here:

  1. The metareview was purposely biased towards studies from China and high fluorosis areas – many of which show endemic fluorosis. It is not directly relevant to the issue of CWF;
  2. The articles reviewed were in themselves mostly of poor quality, did not consider confounding factors and were often very brief (see figure). Not the fault of Choi et al., (2012) and hardly a surprising situation for the regions of interest, but this does help put the value of 0.45 standard deviation into context. It is, as yet, really only provisional.

Histogram showing size of the reports reviewed by Choi et al., (2012) from 

Your claim the Fluoridation Review misrepresented Choi et al (2012) in a specific quote.

Choi et al., (2012) themselves say:

“The estimated decrease in average IQ associated with fluoride exposure based on our analysis may seem small and may be within the measurement error of IQ resting.”

This is a valid assessment because the mean difference they observed amounted to only 0.45 of a standard deviation which can be related to measurement error.

The Review refers to this text (and quotes as section of it) as follows:

The authors themselves note the difference is so small that “it may be within the measure tn error of IQ testing.”

I really don’t see any misrepresentation there. The authors did note that the difference was small compared with measurement error.

In summary I reject your criticisms on this issue for these reasons:

  1. You have relied for claims on a metareview of studies from areas of endemic fluorosis. A study reviewing reports of mainly poor quality and which the authors had described as not relevant to areas using CWF.
  2. You misrepresent correction of the small mistake as a change in recognition of the science or a “misreading of the available evidence.” There was no change as the science was correctly reported in the body of the review – the mistake occurred only in the summary. Others have made similar  mistakes – including Harvard University in their press release.
  3. You repeatedly refer to an IQ point differences of 7 without at any time considering how significant this value is compared with the measurement errors.
  4. You imply that this issue was not thoroughly addressed, which is wrong as it was discussed in the body of the review. Correction of the mistake in the summary is all that was required.

But, I stress again, whatever the significance of the small IQ differences reported for areas with endemic fluorosis in these studies they are not relevant to areas like NZ where no IQ deficits have been reported for CWF. In fact, quite the opposite (Broadbent et al., 2014).

Claims of neglected evidence

You  express concern “relevant evidence” was neglected by the authors of the review.

You refer to 2 papers:

1: Cheng and Lynn (2013) and a study “(referred to by Cheng and Lynn).” However, you do not attempt to explain what this paper contributes. The journal (it is in Mankind Quarterly) is not one normally considered for publishing scientific papers and is extremely difficult to access. My reading of the paper indicates nothing new – in fact it is a repetition of the data from the Choi et al., (2012) paper (which I find strange as it doesn’t even cite that paper).

Why do you wish Mankind Quarterly to be cited? Published by the Ulster Institute for Social Research (and not a scientific body), Wikipedia describes it this way:

“It has been called a “cornerstone of the scientific racism establishment” and a “white supremacist journal”, “scientific racism’s keepers of the flame”, a journal with a “racist orientation” and an “infamous racist journal”, and “journal of ‘scientific racism'”.

2: The cross-sectional study by Saxena et al., (2012). I agree this wasn’t included – but then again it is not relevant to CWF. The study considered situations where drinking water F concentration was greater than 1.5 ppm.

Unfortunately the images you reproduce could give a misleading impression. The linear plot in your figure was actually for the relationship between urine F concentration and drinking water concentration.

The plot for intelligence grade does not look so impressive (see figure).

Saxena

Saxena et al., (2012 ) do show an increase in mean intelligence grade (corresponding to a decrease in IQ) for the increasing concentration ranges. (You should perhaps note your reference to a standard deviation of 15 in such studies is clearly irrelevant to this study). They admit to several limitations in their study. We can agree with their assertion there is a “need for a more careful evaluation of the effect of fluoride on intelligence.” But given the endemic fluorosis in the area they studied, and in the areas of the studies reviewed by Choi et al., (2012) and studied by Choi et al., (2015) I suggest this is only relevant to such areas. I stress –  no such IQ differences were observed in areas where CWF is used (Broadbent et al., 2014).

I am aware of a number of other studies reporting cognitive deficits in areas of endemic fluorosis – suggesting IQ may well be a topical area of research in such areas. The NZ Fluoridation Review may not have cited these – precisely because they are not relevant to our situation.

However, I will reproduce some data from one of them (Sudhir et al., 2009) because it is directly relevant to the next topic. These authors did see increasing cognitive deficits with increasing concentration of F in drinking water. But they also saw a strong relationship between cognitive deficit and severe dental fluorosis (see figure below).

Sudhir

In this study IQ grade 5 is “intellectually impaired” and grade 3 is “intellectually average.”

Severe dental fluorosis and cognitive deficits

I stressed at the beginning of this letter that these IQ studies have all (except for Broadbent et al., 2014) concentrated on areas of endemic fluorosis. Children in these areas show high incidence of severe dental fluorosis and this is quite different to New Zealand (see the second figure in this letter). It is also noteworthy that Choi et al., (2015) chose to extend their work in an area of endemic fluorosis (in a Chinese village) and not an area of the USA where CWF is common. Maybe they recognise this is a problem for areas of endemic fluorosis and not for areas using CWF.

Unfortunately researchers like Choi et al., (2015) have limited their working hypothesis only to chemical toxicity. But, dental defects are known to cause decreased quality of life and this could be translated into learning difficulties and reduced IQ scores. In a recent article I suggested these researchers widen their considerations to including the hypothesis that severe dental fluorosis, in itself, could be a cause of cognitive deficits simply because of the effect of physical anomalies and appearance on IQ (see Perrott 2015).

This is, after all, consistent with their findings that cognitive deficits were significantly related to incidence of severe/medium dental fluorosis but not to the F concentration in the drinking water.

Other oral defects like bad dental decay are also known to cause a reduced quality of life and may lead to learning problems and cognitive deficits. While severe dental fluorosis is a problem in  areas of endemic fluorosis it is not here. I suggest you worry more about possible IQ effects of tooth decay than any due to fluoride in our drinking water.

You are just scaremongering with your flight of fancy suggesting that “institutionalizing the additional proportion of the population due to mental deficiency” should be considered as a cost against CWF. One could more sensibly say that in NZ the quality of life and possible cognitive deficits arising from dental decay should be considered as a cost against opposition to CWF.

Conclusion

Your letter is part of an ongoing campaign by New Zealand anti-fluoridation activists like FFNZ and New Health NZ to discredit the NZ Fluoridation Review. New Health NZ is part of the NZ Health Trust, a well-funded lobby group for the “natural”/alternative health industry in New Zealand. It campaigns on issues like fluoridation, vaccinations and “chemtrails” (see Who is funding anti-fluoridation High Court action? and Corporate backers of anti-fluoride movement lose in NZ High Court).

On the surface your complaint about the mistake in the summary of the NZ Fluoridation review is at least churlish. Especially as it was corrected when brought to the authors’ attention and there was no mistake in the body of the review. Despite the same mistake in the original version of Harvard University’s press release on the research neither you nor your colleagues in the NZ anti-fluoride movement have complained to Harvard University.

One would have though the correction of the mistake would have pulled the rug out from under the anti-fluoridation critics but you have unjustly tried to use the original mistake to argue that the authors of the NZ Fluoridation Review misunderstood or misrepresented the science. In fact, the misrepresentation comes from you and your anti-fluoridation colleagues as the study you seem to pin all your arguments on was made in areas of endemic fluorosis,  (mainly in China) and has no direct relevance to New Zealand CWF.

New Zealand health professionals and members of local bodies should see your complaint for what it is – part of the ongoing activist campaign against CWF. These decision makers are justified in the confidence they have in the NZ Fluoridation Review.

Yours sincerely,

Dr Ken Perrott

References

Beltrán-aguilar, E. D., & Barker, L. (2010). Prevalence and Severity of Dental Fluorosis in the United States , 1999 – 2004 (pp. 1999–2004).

Broadbent, J. M., Thomson, W. M., Ramrakha, S., Moffitt, T. E., Zeng, J., Foster Page, L. A., & Poulton, R. (2014). Community Water Fluoridation and Intelligence: Prospective Study in New Zealand. American Journal of Public Health, 105(1), 72–76.

Cheng, H., & Lynn, R. (2013). The adverse effect of fluoride on Children’s intelligence: A systematic review. Mankind Quarterly, 53, 306–347.

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., Grandjean, P., Sun, G., & Zhang, Y. (2013). Developmental fluoride neurotoxicity: Choi et al. Respond. Environmental Health Perspectives, 121(3), A70.

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.

Eason, C., & Elwood, JM. Seymour, Thomson, WM. Wilson, N. Prendergast, K. (2014). Health effects of water fluoridation : A review of the scientific evidence (p. 74).

Fluoride Free New Zealand. (2014). Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report

Hansen, L. (2015). An open letter to the Prime Minister’s Chief Science Advisor and to the President of the Royal Society of New Zealand.

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

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

Saxena, S., Sahay, A., & Goel, P. (2012). Effect of fluoride exposure on the intelligence of school children in Madhya Pradesh, India. Journal of Neurosciences in Rural Practice, 3(2), 144–9.

Sudhir, K. M., Chandu, G. N., Prashant, G. M., & Reddy, V. V. S. (2009). Effect of fluoride exposure on Intelligence Quotient ( IQ ) among 13-15 year old school children of known endemic area of fluorosis , Nalgonda District , Andhra Pradesh . JOURNAL OF THE INDIAN ASSOCIATION OF PUBLIC HEALTH DENTISTRY, 2009(13), 88–94.

Xiang, Q. (2014) Fluoride and IQ research in ChinaKeynote Address at FAN’s 5th Citizens’ Conference on Fluoride.

 

 

 

 

 

February ’15 – NZ blogs sitemeter ranking

blog-breakdown

Image credit: Dear Kitty. Some blog

There are now over 300 blogs on the list, although I am weeding out those which are no longer active or have removed public access to sitemeters. (Let me know if I weed out yours by mistake, or get your stats wrong).

Every month I get queries from people wanting their own blog included. I encourage and am happy to respond to queries but have prepared a list of frequently asked questions (FAQs) people can check out. Have a look at NZ Blog Rankings FAQ. This is particularly helpful to those wondering how to set up sitemeters.

Please note, the system is automatic and relies on blogs having sitemeters which allow public access to the stats.

Here are the rankings of New Zealand blogs with publicly available statistics for February 2015. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers.

Meanwhile I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

Subscribe to NZ Blog Rankings

Subscribe to NZ blog rankings by Email

Find out how to get Subscription & email updates

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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.

special-pleading-fallacy

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.

DF---good-and-bad

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:

References

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?

Oldfield-Poster-2015

 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

CWF-safe-report

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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January ’15 – NZ blogs sitemeter ranking

Social-Media-Statistics-You-Need-to-Know1

Credit: 10 Social Media Facts, Figures and Statistics You Need to Know

There are now over 300 blogs on the list, although I am weeding out those which are no longer active or have removed public access to sitemeters. (Let me know if I weed out yours by mistake, or get your stats wrong).

Every month I get queries from people wanting their own blog included. I encourage and am happy to respond to queries but have prepared a list of frequently asked questions (FAQs) people can check out. Have a look at NZ Blog Rankings FAQ. This is particularly helpful to those wondering how to set up sitemeters.

Please note, the system is automatic and relies on blogs having sitemeters which allow public access to the stats.

Here are the rankings of New Zealand blogs with publicly available statistics for January 2015. Ranking is by visit numbers. I have listed the blogs in the table below, together with monthly visits and page view numbers.

Meanwhile I am still keen to hear of any other blogs with publicly available sitemeter or visitor stats that I have missed. Contact me if you know of any or wish help adding publicly available stats to your bog.

You can see data for previous months at Blog Ranks

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Hypocrisy

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

Fluoride Free NZ report disingenuous – conclusion

This is the third and last article 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 (hereafter refered to as the Royal Society Review).

My first article, Peer review of an anti-fluoride “peer review” discussed Kathleen Theissen’s contribution. (It also discussed a draft contribution by Chris Neurath which does not appear in the final version). The second article, Cherry-picking and misinformation in Stan Litras’s anti-fluoride articlecritiques Stan Litras’s contribution. This one discusses H. S. Micklem’s contribution.

See The farce of a “sciency” anti-fluoride report for an analysis of the close relationships between the authors and peer reviewers of the Fluoride Free NZ report and anti-fluoride activist groups.

There are a few smaller articles by Paul Connett and Mark Atkins. They do not deal with the contents of the Royal Society Review so I will not comment on them here.

This article below completes my critique of the Fluoride free NZ report.


H. S. Micklen, who wrote the second article in the Fluoride Free NZ report, is one of the coauthors, together with Paul Connett, of the book  The Case against Fluoride which anti-fluoride activists treat as gospel. His article was “peer-reviewed” by James Beck, the other co-author of the book.

In my comments I use the section headings used by H. S. Micklem.

Dental fluorosis

I think Micklen’s comments on dental fluorsis are quite muddled. He confuses the relevance of the different grades of dental fluorosis and unfairly attributes the more severe forms to community water fluoridation (CWF). Consequently he calculates a cost of dental treatment which is wrong.

Recently I put dental fluorosis, its different grades and its contribution to oral health satisfaction into context with the image below (see Water fluoridation and dental fluorosis – debunking some myths):

Dental fluorosis of grades none, questionable, very mild and mild are common in countries suitable for CWF – in both fluoridated and unfluoridated areas. Fluoridation may cause a small increase in mild grades. But these first 4 grades (none – mild) are judged purely “cosmetic. In fact children and parents often judge the grades “questionable – mild” more highly than “none.” Research finds these milder forms of dental fluorosis often improve dental health related 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).

Micklem is straw-clutching to take one reference used by the Royal Society Review out of context to imply that these studies are wrong because “subjects liked the appearance of a complete set of artificially white teeth.” He says “they did not like the whiteness associated with fluorosis.”  But the authors actually say:

“The ranking of images of teeth with a fluorosis score of TF 1 may lead to the inference this sample of 11 to 13 year olds do not consider milder presentations of fluorosis to be aesthetically objectionable. The very white teeth represented an unnatural presentation that could only be achieved by cosmetic procedures. . . . This is consistent with previous work related to dental aesthetics [18,19] whereby teeth with mild forms of fluorosis (TF 1, TF2) were rated similarly.”

Micklem raises the bogey of the cost of veneers (up to $1750 per tooth) but this is just scaremongering as veneers would not be used for teeth with these mild grades of fluorosis.

Moderate and severe grades of dental fluorosis are common in areas where fluorosis is endemic, but relatively rare where CWF is used. Occurences in the later 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.

Treatment of moderate and severe cases of dental fluorosis using veneers may well be appropriate for a very few young people in countries like New Zealand and the US but it is misleading to attribute this to CWF. Interestingly, Micklem’s misattribution mirrors that of Ko and Thiessen (2014). They also assumed all moderate and  severe dental fluorosis was caused by CWF thereby enabling them to declare no cost benefit to CWF because of the required dental treatments.

Micklem has simply continued the anti-fluoride propagandist tradition of confusing data for the relative amounts of different grades of dental fluorosis and attributing problems with the rare moderate and severe forms to the more common questionable and mild forms.

Neurotoxicity and IQ

In this section Micklem attempts to contrast the Choi et al (2012) metareview with the Broadbent et al (2014) study. He erroneously refers to both as being relevant to CWF and “the case that water fluoridation poses a development risk to human intelligence.”

Let’s make this clear. The Choi et al (2012) review did not include studies of CWF. The authors made clear that their results should not be seen as relevant to CWF. Most of the brief reports they reviewed studied areas of endemic fluorosis and Xiang (2014) (one of the authors of an included study) gives some idea of how this is manifested in a title slide to a recent talk.

The only study Micklem comments on that involved CWF was that of Broadbent at al (2014).  Micklem describes this as “inconclusive” but does not say why. Do I detect some bias there?

Given the available studies I think the Royal Society review was justified in concluding “that on the available evidence there is no appreciable effect on cognition arising from CWF.”

Passing on to the question of the Choi et al (2012) metareview, which is not relevant to CWF. Micklen concedes that included studies were individually  “not strong” but argues “the existence of so many studies almost all saying the same (important) thing” should be treated with attention and respect. I agree – but lets not allow that attention and respect to be blind. Let’s be aware of the limitations and attempt to understand what the results might mean.

The authors of that metareview have extended their work to making their own measurements in a pilot study (Choi et al., 2014). In this new paper they did not find a significant relationship between cognitive deficit measurements and drinking water fluoride. We need to accommodate this finding in our assessment of the metareview.

Choi et al (2014) did find a significant association of cognitive deficits with severe dental fluorosis.  Perhaps we need to respect that finding and give it some attention. Rather than the assuming the mechanism of such cognitive deficits is the speculated but unproven neurotoxic activity of fluoride we should be open to other possible mechanisms (Perrott 2015)..

I have done so with my article  and would welcome any feedback Micklem could give on this. I feel that the effects of a physical deformity like severe dental fluorosis on learning is a more realistic mechanism (for which there is a lot of published evidence) than some sort of vague chemical toxicity which has never been noted at these low concentrations.

Incidentally, Micklem attempts to discredit the Royal Society’s understanding of the Choi et al (2012) saying it suggested that the measured IQ reduction was “arguably negligible.” The Royal Society review actually said:

“Setting aside the methodological failings of these studies, Choi et al. determined that the standardised weighted mean difference in IQ scores between “exposed” and reference populations was only -0.45. The authors themselves note that this
difference is so small that it “may be within the measurement error of IQ testing”.[172]”

Choi et al., (2012) said:

“The estimated decrease in average IQ associated with fluoride exposure based on our analysis may seem small and may be within the measurement error of IQ testing.”

And their abstract reported the “standardized weighted mean difference in IQ score between exposed and reference populations was –0.45 (95% confidence interval: –0.56, –0.35).”

There has been some confusion because Choi et al., (2012) used a standardised weighted mean difference to accommodate the different IQ scales used in the studies they reviewed. But their warning about the small size of the calculated difference and its relationship to measurement errors in IQ testing is relevant.

The Royal Society Review did indeed make a mistake in the executive summary where it referred to a claimed IQ shift of “less than one IQ point” when it should have said “less than one standard deviation.” I discussed this in Did the Royal Society get it wrong about fluoridation? and noted that even Harvard University made the same mistake in its inital press release of the Choi et al (2012) work.

I think the Authors of the Royal Society Review should correct that mistake, as Harvard University did – but it does not change the fact there is no mistake in the review’s evaluation of the Choi et al (2012) paper.

Lead

In this section Micklem attempts to cast doubt on the Royal Society Review’s comments on the form of fluoride in drinking water and a possible role of fluoride in releasing lead from pipe fittings.

The hydrolysis of fluorosilicic acid when diluted during water treatment may not be completely understood (nothing ever is) but recent high quality research (Urbansky & Schock 2000; Urbansky 2002; Finney et al., 2006) has confirmed the review’s statement it is “effectively 100% dissociated to form fluoride ion under water treatment conditions.” Despite acknowledging the need for more and better research Urbansky (2002) concluded “all the rate data suggest that equilibrium should have been achieved by the time the water reaches the consumer’s tap if not by the time it leaves the waterworks plant.”

This debate only exists among anti-fluoride propagandists because of selective and motivated reliance on old and poor quality research, together with confirmation bias. For example, the report by Crosby (1969) that “evidence from specific-ion electrode and conductivity measurements at 25° confirms that sodium fluorosilicate, at the concentration normally present in public water supplies, is dissociated to at least 95%” is interpreted by Coplan et al., (2007) as “proof” the fluorosilicate is 5% unhydrolysed!

Micklem relies on then papers of Master et al., (2000), Copelan et al 2007 and Mass et al., (2007) to argue that fluoride treatment chemical enhances lead release from pipes. However, I think an objective assessment of these paper would conclude the authors argue determinedly for a preconceived hypothesis and that many of their arguments are irrelevant and faulty. This is not to dismiss their finding on lead levels in drinking water – but as Masters et al., (2000) themselves point out – “statistical association should not be confused with causation.” 

Similarly, I suggest that Micklen’s reliance on Sawan et al., (2010) to support Copelan’s hypothesis amounts to special pleading as those workers used drinking water concentration of 100 mg/L of fluoride and 30 mg/L of lead.

Osteosarcoma

Micklem uses the old anti-fluoride activist trick of fixating on a cherry-picked paper which fits his agenda and downplaying or attempting to discredit papers which don’t. He concentrates on Bassin et al (2006), despite its description by its authors as “an explanatory study” requiring “further research” to “confirm or refute” its conclusions. That paper fits Micklem’s agenda because it found a statistically increased risk of osteosarcomas in male boys exposed to water fluoridated at 1.2 mg/L F.

In such a complex area, for a cancer with such a low incidence, a balanced overall consideration of research reports is necessary. All papers have their advantages and drawbacks so conclusions should be derived from proper consideration of the total research findings – as the Royal Society review appears to have done.

The Bassin (2006) findings have not been confirmed by any later work – despite a range of such studies (Kim et al., 2011; Comber et al., 2011; Levy and Leclerc 2012; Blakey et al., 2014). The Royal Society Review pointed out previous reviews had all concluded that “based on the best available evidence, fluoride could not be classified as carcinogenic in humans.” And that “more recent studies have not changed this conclusion.”

Micklem hasproduced nothing to counter that conclusion.

Cardiovascular and renal effects

Micklen attempts to use the paper, Martín-Pardillos et al., (2014), cited by the Royal Society Review, against the reviews conclusions. The review presents the paper this way:

“A number of studies indicate that fluoride may reduce aortic calcification in experimental animals and humans.[199] This preventive effect was recently confirmed by in vitro experiments, but in vivo findings from the same studies showed the opposite result – that phosphate-induced aortic calcification was accelerated following exposure of uremic rats to fluoride in water at around 1.5 mg/L.[200] The authors suggested that chronic kidney disease could be aggravated by relatively low concentrations of fluoride, which (in turn) accelerates vascular calcification. However, further studies are required to test this hypothesis.”

Martín-Pardillos et al., (2014) proceeded from the hypothesis that fluoride did not initiate calcification but because it is attracted to calcified deposits it may influence subsequent crystallisation of the calcified material.

Their in vitro results indicated a protective effect against calcification. While the opposite was observed with the 5/6 nephrectomised rats with induced calcification they still concluded:

“The direct inhibition of ectopic calcification could still occur in vivo when the renal function is correct, such as during aging or even the initial stages of diabetes, and this possibility deserves further research.”

This is relevant to healthy humans without chronic kidney disease (CKD).

The acceleration of induced vascular calcification with the 5/6 nephrectomised rats does raise the need for further studies, and monitoring the situation with humans suffering CKD. But let’s not forget the rat model was extreme. Rats had all of one kidney and 2/3 of the other kidney removed. They were also fed a phosphate enriched diet and the induced CKD was clearly indicated by urea and creatine blood concentration.

Of course these findings are relevant when considering ongoing research and monitory the situation of CKD human patients. As the authors say “the effects of fluoride on renal function and vascular health are more complicated than expected.”

However, the current advice of the National Kidney Foundation is that:

“Dietary advice for patients with Chronic Kidney Disease (CKD) should primarily focus on established recommendations for sodium, calcium, phosphorus, energy/calorie, protein, fat, and carbohydrate intake. Fluoride intake is a secondary concern.”

Given that such patients are already monitory their diet and more advanced cases also probably regularly monitory blood indicators  any possible effect of fluoride for individuals should be detected. It is likely that by the time any problem with fluoride in drinking water is indicated other problems will also have occurred and patients will be taking steps such as water filtering and careful dietary management to handle their situation.

In fact individually directed management of food and drinking water appears to be a sensible way of handling problems if they do occur with a few people.

Micklem’s “call for CKD sufferers to be warned to avoid tap water” is too extreme and alarmist. Already the advice is that persons with CKD should be notified of the potential risk of fluoride exposure and be kept up to date with new research. 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 policy like CWF.

Conclusions

This completes my critique of the Fluoride Free NZ report.

The original Royal Society review, Health Effects of Water Fluoridation: a Review of the Scientific Evidence, was prepared in response to a request from councils for a summary of the current science on CWF. This is because over the last few years activists political groups, like Fluoride Free NZ (and its international associate Fluoride Action Network) have bombarded New Zealand councils with misinformation and distortion of the science in campaigns to prevent CWF or get it removed

Councils do not have the expertise to critical consider claims made by such activist groups and have adopted a policy of requesting central government take over their responsibilities on the issue. Until that happens, however, councils will continue to have such decisions forced upon them.

The Royal Society review provides a timely and authoritative source of information for councils. Understandably Fluoride Free NZ feels somewhat trumpted by the review. So it is understandable this activist groups, and the international associate will use their media influence to try to discredit it.

This report is an attempt to fool councils by pretending to be objective and international. Yet, as my articles in this series show, it is simply a put-up job. It is not objective – all the authors and “peer reviewers” are working for or associated with the Fluoride Action Network or its associates. The articles follow the typical cherry-picking and confirmation bias of such activist organisations.

See The farce of a “sciency” anti-fluoride report for an analysis of the close relationships between the authors and peer reviewers of the Fluoride Free NZ report and anti-fluoride activist groups.

The Fluoride Free report is simply disingenuous – a sham aimed at fooling councils.

References

Bassin, E. B., Wypij, D., Davis, R. B., & Mittleman, M. a. (2006). Age-specific fluoride exposure in drinking water and osteosarcoma (United States). Cancer Causes & Control : CCC, 17(4), 421–8.

Biazevic, M. G. H., Rissotto, R. R., Michel-Crosato, E., Mendes, L. A., & Mendes, M. O. A. (2008). Relationship between oral health and its impact on quality of life among adolescents. Brazilian Oral Research, 22(1), 36–42.

Blakey, K., Feltbower, R. G., Parslow, R. C., James, P. W., Gómez Pozo, B., Stiller, C., … McNally, R. J. (2014). Is fluoride a risk factor for bone cancer? Small area analysis of osteosarcoma and Ewing sarcoma diagnosed among 0-49-year-olds in Great Britain, 1980-2005. International Journal of Epidemiology, 43(1), 224–34.

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