Category Archives: New Zealand

Cherry-picking and misinformation in Stan Litras’s anti-fluoride article

This is the second article in a series critiquing contributions to the Fluoride Free NZ report Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report.”

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).

I will shortly post a 3rd article discussing 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 report and anti-fluoride activist groups.

There is a lot in Stan Litras’s article to criticise – there is a lot which is misleading or outright wrong. I hope Stan will seriously consider my criticisms and respond to them, especially where he thinks I am wrong.

My criticisms should also be considered by Bruce Spittle and Hardy Limeback who Fluoride Free NZ listed as “peer reviewers” of Stan’s article. They must bear some responsibility for allowing the article to go ahead without the necessary corrections.

Litras makes many of his criticisms of community water fluoridation (CWF) in passing – without argument or evidence. But he declares:

“My comments will focus on the gross over statement of the purported benefits of fluoridation in our society, New Zealand, 2014.”

So, I will start with the claims he makes on this.

“Overseas studies” – The WHO data

Central to this are Stan’s assertions:

“The “elephant in the room” is that while decay rates fell in areas where fluoridation was implemented, it also fell in areas that weren’t, often at a faster rate. (8)”


“Globally, fluoridation is seen to make no difference to reduced decay rates, there being no difference between the few countries which use artificial fluoridation, and those that don’t. (8,7)”

His only evidence for this is a figure prepared by Chris Neurath from the Fluoride Action Network – using data from the World Health Organisation (WHO). Here it is in a slightly simpler version to the one used by Stan.

I am amazed that anti-fluoride propagandists keep using this graphic as “proof” that fluoride is ineffective. But they do – which can only mean they haven’t thought it through.

While the plots do show improvements in oral health for countries independent of fluoridation they say nothing about the effect of fluoride. Simple comparison of countries obscures all sorts of effects such as differences in culture, history, social and political policies, etc. Such plots are also influenced by changes and differences in dental treatment and measurement techniques.

Robyn Whyman in his report Does delayed tooth eruption negate the effect of water fluoridation? exposes the little trick Stan is trying to pull with the WHO data:

“Studies that appropriately compare the effectiveness of water fluoridation do not compare poorly controlled inter-country population samples. They generally compare age, sex, and where possible ethnicity matched groups from similar areas. Inter-country comparisons of health status, including oral health status, are notoriously difficult to interpret for cause and effect, because there are so many environmental, social and contextual differences that need to be considered.”

There are some within country data within the WHO data set Neurath used which can give a better idea of the beneficial effects of fluoridation. This plot shows the results for the WHO data for Ireland. A clear sign that fluoridation plays a beneficial role.

Neurath covered up evidence for the benefits of CWF by simply using the mean of fluoridated and unfluoridated areas for countries like Ireland and New Zealand. Also, the straight lines in Chris Neurath’s plots are a real give away to the poor quality of the data used. Two data points for each country!

New Zealand – Cherry-picking the MoH data

I have criticised Stan’s misrepresentation the Ministry of Health (MoH) data before. At the time he was using and misrepresenting some of my own graphics on his business website. He has since removed the offending article but now he returns with a vengeance – with tables and figures of his own.

This has given him free hand to cherry-pick and misrepresent to his heart’s content.

He claims:

“Ministry of Health figures recorded every year in 5 year olds and year 8s (12-13 year olds) consistently show minimal or no differences between fluoridated and nonfluoridated areas of NZ.”


Cherry-picked data from Stan Litras

And he backs this up with a graph.

That looks about right. The data for 2011 shows 59.9% of 5 year olds in fluoridated areas were caries-free while 59.2% were carries free in non-fluoridated areas. No real difference.

But come on! A single data point, one year, one of the age groups for the fluoridated and unfluoridated areas! That is blatantly cherry-picking – as I mentioned in my article Cherry picking fluoridation data. In that I presented all the data for 5 year olds and year 8s, and for the total population and Maori, and for % caries free and decayed, missing and filled teeth (DMFT).

I have reproduced this data here in a simpler form using several figures.

caries-freeConsidering the % caries free data there are several points:

1: These do not “consistently show minimal or no differences between fluoridated and nonfluoridated areas” as Stan claims.

2. They do show a decline in differences between fluoridated and non-fluoridated areas in recent years.

3: This trend is less obvious for Maori but still present.

4: Stan has blatantly cherry-picked the  data points for 5 year-olds in 2011 to give him the least possible difference (see red circle in figure).


The data for decayed, missing and filled teeth (DMFT) shows similar trends.

Presumably both measures (% caries free and DMFT) are useful indicators of oral health but they probably convey complementary and not exactly the same information.

I discussed features of the graphs and their trends in in my articles Cherry picking fluoridation data and Fluoride debate: Response to Paul’s 5th article where I also discussed limitations in the data.

We need to appreciate this is just normal school clinic data, without technique standardisation for those making the measurements or proper recording of place of residence. The latter effect probably shows up more strongly after 2004 when a “hub and spoke” dental clinics system was introduced further confusing proper records of likely fluoride intake. One school dental clinic could serve a number of areas – both fluoridated and non-fluoridated. This mixing is a likely explanation for the apparent decline of the effectiveness of fluoridation after 2006.

So, yes, the MoH data is not straightforward. But this means it should be considered sensibly, taking into account its limitations and the social factors involved.  Instead, Stan has leapt in – found the data points which best fit his own biases and then tried to claim those data  are representative when they aren’t.

Stan presented another self-prepared graphic using data for the 4 different regions for 5 year olds (see his page 27). He appears not to have used the correct data – at least for the Northern and Southern regions.  My own graphic for this shows differences to his. (Of course, the mistake may be mine – if Stan can show I am wrong I will happily delete this part from my critique).


Again, that data should also not just be considered at face value – or selected to confirm a bias. It has limitations. For example in this case there were only 55 children in the fluoridated Southern region compared with 7568 in the non-fluoridated area. A footnote on the data sheet says:

“2. Excludes Southern DHB because data were not reported for 1 Jan-20 Feb 2012, and fluoridation status was not captured for most children throughout 2012, due to transition to a new data system. “

Proper consideration of such data must take these sort of limitations into account. But of course all Stan Litras did was select data to support his assertions and ignore the rest. Any limitations in the data did not concern him.

Lifetime benefit

Stan has a thing about the “lifetime benefits,” or lack of benefits, of CWF. Most studies of CWF have used data for children – data for adults is less common but there is still research literature on this available.

But all Stan did on this was to cherry-pick a graphic (Figure 53) from the NZ Oral Health Survey showing no significant change in DMFT for 65-74 year olds between the years 1976, 1988 and 2009. He then claims:

“Data from the NZOHS 2010 do not support statements of a lifetime benefit, indicating that the action of fluoride is simply to delay the decay. (13)”

But he has had to work hard to avoid other data like that in Figure 49 below which do show a significant improvement in the number of retained teeth of that age group. The Oral Health Survey report itself says:

“In dentate adults aged 65–74 years, the mean number fell from 17.1 to 12.1 missing teeth per person on average from 1976 to 2009.”


Again, instead of cherry-picking, searching for an image to fit his story, Stan should have considered the data and figures critically and intelligently. Perhaps the DMFT data does not show what he claims because more teeth have been retained in recent years. The decline in missing teeth could have been balanced by increases in fillings due to increase in remaining teeth. The lack of a significant difference in DMFT actually suggests the opposite to what he claims.

Litras also misrepresent the York review on the question of benefits from CWF for adults. He says:

“The York Review found there was no weight of evidence to support benefit in adults or in low SES groups, or increase of decay in cessation studies. (7)”

Just not true. The York report says:

“One study (Pot, 1974) found the proportion of adults with false teeth to be statistically significantly greater in the control (low-fluoride) area compared with the fluoridated area.”

Sheiham and James (2014) stressed that a proper assessment of oral health problems should include data for adults as well as children. Recent research is starting to take up this issue. For example O′Sullivan and O′Connell (2014) recently showed that water fluoridation provides a net health gain for older Irish adults.

Systemic vs topical

Stan promotes the common mythology of the anti-fluoridation propagandist that any mechanism for a beneficial effect of fluoride in restricting tooth decay is purely “topical.” He claims:

“It has been widely accepted since the 1990s that any effect on tooth decay from swallowing fluoride is insignificant or non-existent. To quote: CDC 1999: “the effect of Fluoride is topical “ (5); J Featherstone 1999: “the systemic effect is, unfortunately, insignificant” (6).”

Let’s consider what the sources Stan cites actually do say. I will quote from the 2001 edition of Stan’s citation 5 which he (partly) cites on page 36:

“Fluoride works to control early dental caries in several ways. Fluoride concentrated in plaque and saliva inhibits the demineralization of sound enamel and enhances the remineralization (i.e., recovery) of demineralized enamel (12,13 ). As cariogenic bacteria metabolize carbohydrates and produce acid, fluoride is released from dental plaque in response to lowered pH at the tooth-plaque interface (14 ). The released fluoride and the fluoride present in saliva are then taken up, along with calcium and phosphate, by demineralized enamel to establish an improved enamel crystal structure. This improved
structure is more acid resistant and contains more fluoride and less carbonate (12,15–19 ) (Figure 1). Fluoride is more readily taken up by demineralized enamel than by sound enamel (20 ). Cycles of demineralization and remineralization continue throughout the lifetime of the tooth.”



“Saliva is a major carrier of topical fluoride. The concentration of fluoride in ductal saliva, as it is secreted from salivary glands, is low — approximately 0.016 parts per million (ppm) in areas where drinking water is fluoridated and 0.006 ppm in nonfluoridated areas (27 ). This concentration of fluoride is not likely to affect cariogenic activity. However, drinking fluoridated water, brushing with fluoride toothpaste, or using other fluoride dental products can raise the concentration of fluoride in saliva present in the mouth 100-to 1,000-fold. The concentration returns to previous levels within 1–2 hours but, during this time, saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization (28 ).”

(Note: Stan simply quotes the first part of this statement (in red) in his article (page 36) and completely omits the second part (in black) – presumably because he wants to deny a role for fluoridated water in influencing the saliva fluoride concentrations. This cherry-picking of the CDC statement is typical for anti-fluoride propagandists – see Fluoridation – topical confusion).

There is an attempt to confuse a “topical” or “surface” mechanism with a “topical” application (eg toothpaste or dental treatments). However, fluoride is transferred to saliva from food and drink during ingestion so that ingested fluoride also contributes to the “topical” or “surface” mechanism.

However Stan wants to deny a “topical” role for ingested fluoride and claims (page 36):

“The required elevation of baseline levels only occurs after using fluoridated toothpaste or mouth rinse, a concentration of 1,000 ppm or more instead of 1 ppm from water.(24)”

His citation 24 is to Bruun (1984) and he misrepresents that paper which actually said:

“It was concluded that direct contact of the oral cavity with F in the drinking water is the most likely source of the elevated whole saliva fluoride and that the increased availability of fluoride in the oral fluids has an important relationship to the reduced caries progression observed in fluoridated areas.”

Systemic role.

Featherstone does say:

“Fluoride works primarily via topical mechanisms which include (1) inhibition of demineralization at the crystal surfaces inside the tooth, (2) enhancement of remineralization at the crystal surfaces (the resulting remineralized layer is very resistant to acid attack), and (3) inhibition of bacterial enzymes. Fluoride in drinking water and in fluoride-containing products reduces tooth decay via these mechanisms. Low but slightly elevated levels of fluoride in saliva and plaque provided from these sources help prevent and reverse caries by inhibiting demineralization and enhancing remineralization. The level of fluoride incorporated into dental mineral by systemic ingestion is insufficient to play a significant role in caries prevention. The effect of systemically ingested fluoride on caries is minimal.”

There is some debate over the role of systemic fluoride exuded by salivary glands. Many feel the concentration is too low – but because its effect is also determined by the presence of calcium, phosphate, organic species and pH it is best not to be dogmatic about this. It is, anyway, difficult to separate salivary fluoride derived from transfer from food and beverage in the oral cavity from that exuded by the salivary glands from systemic sources.

Stan is determined to deny a role for systemic fluoride during tooth development asserting:

“the erroneous theory that fluoride incorporated into children’s developing tooth enamel would make teeth more resistant to decay.”

While often neglected because of the concentration on surface mechanisms with existing teeth the theory that fluoride is incorporated into the developing teeth of children and confers a degree of protection is far from erroneous.

Newbrun (2004), for example, stressed in a review of the systemic role of fluoride and fluoridation on oral health:

“The role of systemic fluoride in caries prevention is neither “minimal” nor “of borderline significance.” On the contrary, it is a major factor in preventing pit and fissure caries, the most common site of tooth decay. Maximal caries-preventive effects of water fluoridation are achieved by exposure to optimal fluoride levels both pre- and posteruptively.”

Cho et al (2014) presented data showing that children exposed to CWF during teeth development retained an advantage over those never exposed to it even after fluoridation ceased.

Let’s stop confusing the issue. Systemic fluoride may not play a role with existing teeth but it does during tooth development – even if the relative contributions of systemic fluoride and “topical” or surface fluoride to lasting oral health are difficult to determine.

Tooth eruption delays

Stan resorts to special pleading when he claims with reference to NZ MoH data:

“Small apparent differences could be accounted for by other factors such as delayed eruption of teeth in fluoridated communities, therefore less time in the mouth exposed to plaque acids, ethnic distribution and urban/rural differences.”

He relies on the “York review” (McDonagh et al., 2000) to back up his “delayed tooth eruption” excuse:

“Importantly, the York Review noted that the variation of tooth eruption times between fluoridated and unfluoridated areas was not taken into account. (7)”

But that review actually said on this subject:

“It has been suggested that fluoridation may delay the eruption of teeth and thus caries incidence could be delayed as teeth would be exposed to decay for a shorter period of time. Only one study compared the number of erupted teeth per child. The difference was very small and in opposite directions in the two age groups examined, however no measure of the statistical significance of these differences was provided. Only one of the studies attempted to control for confounding factors using multivariate analysis (Maupomé 2000).”

Robyn Whyman has gone into this claim in more detail in his report Does delayed tooth eruption negate the effect of water fluoridation?Here he critiques Paul Connett’s reliance on this excuse and concludes from his review of the literature:

“The studies and reports cited by Professor Connett to try and validate an argument for delayed tooth eruption either do not make the claims he suggests, or do not have direct relevance to trying to assess the issue. The claimed association is at odds with the published literature which indicates minimal variation in eruption time of permanent teeth by exposure to fluoride. A rational explanation exists for the minimal variations that have been reported based on the relationship between fluoride exposure, caries experience in the primary teeth and emergence timing for the permanent teeth.”

The “delayed tooth eruption” excuse is nothing more than special pleading and straw clutching.

Socio-economic factors

Stan again misrepresented the York review regarding socio-economic effects on oral health and the effectiveness of CWF when he claimed “there was no weight of evidence to support benefit in adults or in low SES groups.” The York review actually said:

“Studies should also consider changes in social class structure over time. Only one included study addressed the positive effects of fluoridation in the adult population. Assessment of the long-term benefits of water fluoridation is needed.”


“Within the UK there is a strong social gradient associated with the prevalence of dental caries. This is found both in adults and in children. Those who are more deprived have significantly greater levels of disease. There is also geographical variation with the northwest of England, Scotland and Northern Ireland most severely affected. (Pitts, 1998; Kelly, 2000)”

There have been a range of studies internationally showing that fluoridation can aid in reducing differences in oral health due to socio-economic effects. See for example Cho, et al., (2014).

What happens when fluoridation is stopped

Stan briefly refers to this issue, citing (as anti-fluoridation activists always do) Künzel and·Fischer (2000). I will simply refer him, and interested readers to my article What happens when fluoridation is stopped? This boils down to the need to read the scientific literature properly as usually the anti-fluoridation activists ignore the details referring to fluoride treatments and procedures which replaced CWF.

There are a number of other points mentioned briefly by Stan Litras which could be discussed but this article is already too long so I will leave that to the comments section.


Stan Litras has simply indulged in blatant cherry-picking of data, and misrepresentation of the literature, in his critique of 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. Perhaps we shouldn’t expect better from a political activist in the anti-fluoride movement but he, and Fluoride Free NZ, attempt to present this, and other articles in the collection, as objective and scientifically credible. It is neither – such cherry-picking and misrepresentation violates any scientific ethics and needs to be exposed for what it is. The Fluoride Free NZ claimed “peer reviewers,” Bruce Spittle and Hardy Limeback, must share responsibility because, by their endorsement, they signal their approval of such behaviour.


I offered Stan Litras a right of reply to this post, or even an ongoing exchange with him along the lines of my debate with Paul Connett. He replied:

“I look forward to your comments on my review, as a lay person, but I cannot engage in a serious dialogue with someone who is not a peer with the same level of knowledge as myself in the dental field. “

Hopefully this means he will at least comment here, take issue with me where he thinks I am wrong and correct me where I am mistaken. I also hope than Bruce Spittle and Hardy Limeback will also take advantage of their right to comment here.


Bruun, C., & Thylstrup, A. (1984). Fluoride in Whole Saliva and Dental Caries Experience in Areas with High or Low Concentrations of Fluoride in the Drinking Water. Caries Research, 18(5), 450–456.

Centers for Disease Control and Prevention. (2001). Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States (Vol. 50, p. 50).

Cho, H.-J., Jin, B.-H., Park, D.-Y., Jung, S.-H., Lee, H.-S., Paik, D.-I., & Bae, K.-H. (2014). Systemic effect of water fluoridation on dental caries prevalence. Community Dentistry and Oral Epidemiology.

Cho, H.-J., Lee, H.-S., Paik, D.-I., & Bae, K.-H. (2014). Association of dental caries with socioeconomic status in relation to different water fluoridation levels. Community Dentistry and Oral Epidemiology.

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

Künzel, W.;·Fischer, T. (2000). Caries Prevalence after Cessation of Water Fluoridation in La Salud, Cuba. Caries Res, 34, 20–25. Retrieved from

McDonagh, M., Whiting, P., Bradley, M., Cooper, J., Sutton, A., & Chestnutt, I. (2000). A Systematic Review of Public Water Fluoridation.

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

Ministry of Health (2014) Age 5 and Year 8 oral health data from the Community Oral Health Service.

National Fluoridation Information Service (2011): Does Delayed Tooth
Eruption Negate The Effect of Water Fluoridation? National Fluoridation Information Service Advisory June 2011, Wellington, New Zealand.

O′Sullivan, V., & O′Connell, B. C. (2014). Water fluoridation, dentition status and bone health of older people in Ireland. Community Dentistry and Oral Epidemiology.

Sheiham, A., & James, W. P. T. (2014). A reappraisal of the quantitative relationship between sugar intake and dental caries: the need for new criteria for developing goals for sugar intake. BMC Public Health, 14(1), 863.

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The farce of a “sciency” anti-fluoride report

F network

Click for a larger image

I came up with the image above after a quick glance at a “report” promoted by the local Fluoride Free groups and Paul Connett’s Fluoride Alert organisation. (Scientific and Critical Analysis of the 2014 New Zealand Fluoridation Report). It illustrates the incestuous network of authors and “peer reviewers” involved in producing the “report.” I have also illustrated connections of these people to a number of anti fluoride organisations and 2 publications.

The first column lists the authors in red, and their claimed peer reviewers in green. The third column lists the anti-fluoride organisations and several publications these people are connected to.

The middle column lists some other people who are also connected to these organisations and publications. I have already reviewed Kathleen Theissen’s article (see Peer review of an anti-fluoride “peer review”) and will get around to reviewing the other 2 articles (by H.S. Miclen and Stan Litras) later.

Meanwhile, lets just consider the connections between these authors, “peer reviewers” and anti-fluoride organisations.

Taking in each other’s laundry

Most of these names are familiar to anyone who has followed the anti-fluoride movement. That fact in itself shows how this report can in no way be seen as “expert,” “independent” or at all credible. Some details on the illustrated people, organisations and publications.

NRC Review minority: There were several disagreements on the 12 member panel which produce the 2006 NRC report “Fluoride in drinking water. A scientific review of EPA’s standards” because 3 members were anti-fluoride. They were Robert Issacson, Hardy Limeback and Kathleen Theissen. Hardy Limeback is involved in several anti-fluoride activist groups.

Kathleen Theissen appears not to be organisationally involved but regularly makes anti-fluoridation submissions when the issue is debated.

UPDATE: Steve Slott has reminded me of this example of Theissen’s lack of credibility as a peer reviewer of fluoridation-related papers:

“In July 2013, Douglas Main, that freelance reporter and bastion of “objectivity”, interviewed Thiessen to get her opinion on Hirzy’s study on which he based his petition to the EPA.

From the article:

“Experts not involved with Hirzy’s study agreed with its findings.”

“I think this is a reasonable study, and that they haven’t inflated anything,” said Kathleen Thiessen, a senior scientist at SENES Oak Ridge Inc., a health and environmental risk assessment company.”

When the EPA reviewers looked at Hirzy’s study they found that he had made a 70-fold miscalculation in his study. When corrected for that error, the EPA reviewers found that Hirzy’s data actually demonstrated the exact opposite of what he had concluded.

Seems Thiessen either didn’t bother to read Hirzy”s study prior to commenting on it, or she overlooked his glaring error, too.”

Fluoride/ISFR: The International Society for Fluoride Reasearch (ISFR) publishes the journal Fluoride and organises regular conferences. They provide an avenue for authors to publish anti-fluoride articles, and generally poor quality research from areas where endemic fluorosis is common which may not be acceptable in the normal scientific journal.

The Society is based in New Zealand and is registered here as a charity. Bruce Spittle is the treasurer and journal managing editor.

FTRC/Second look: The anti-fluoride organisation and web site Second Look as set up the Fluoride Toxicity Research Collaborative (FTRC). It appears to be a weak attempt to provide a front “scientific institute” for anti-fluoride activists who want to present themselves as scientific experts.

This reminds me of the creationist Biologic Institute set up by the intelligent design creationists at the Discovery Institute. Actually, the Intelligent Design “pretend” scientific journal Bio-complexity also reminds me of the anti-fluoride journal Fluoride.

The FTRC lists the following staff:

  • Russell Blaylock, M.D., FTRC Medical Director
  • Hardy Limeback, Ph.D., D.D.S, FTRC Principle Investigator
  • Phyllis J. Mullenix, PhD., FTRC Research Program Director
  • Aliss Terpstra, RNCP, FTRC Research Coordinator

So far they claim to have sponsored (financed?) 2 research papers only by Phyllis Mullinex. Have a read of them and make up your own mind about their quality.

Case Against Fluoride: This is Paul Connett’s book The Case against Fluoride: How Hazardous Waste Ended Up in Our Drinking Water and the Bad Science and Powerful Politics That Keep It There. It is usually treated as a holy scripture in the anti-fluoridation movement. His co-authors were H. S. Micklen and James Beck.

Connett is very proud of this book and relies on it to support his claim to be a “world expert” on fluoridation.

Fluorine in Medicine: This is the sole scientific paper that Paul Connett can claim authorship (actually co-authorship) to:

Strunecká, A. ., & Patočka, J.; Connett, P. (2004). Fluorine in medicine. Journal of Applied Biomedicine, 2, 141–150.

The senior author Anna Strunecká is also part of the anti-fluoride network illustrated above. I am personally very suspicious of the quality of the journal which published this paper – anti-fluoride people have a history of placing poor quality papers in suspect journals purely to attain some sort of scientific credibility. DonQuixoteJune2011

FIND: The Fluoride Information Network for Dentists is one of the local Fluoride Free’s astroturf organisations claiming about 8 members but only Stan Litras is active. Stan uses his FIND hat for his anti-fluoride press releases – such as the one promoting the “report” considered here.

NZ Tour of Don Quixote & Sancho Panza: Sorry, can’t help thinking of these two when the upcoming NZ tour of Paul Connett and Bill Hirzy is mentioned. They do seem to be charging local fluoridation windmills with meetings in Taupo and Auckland.

William Hirzy: He is Paul Connett’s wingman on the Don Quixote & Sancho Panza Tour. Unlike Paul’s sole co-authorship he actually has 2 published scientific papers related to fluoridation where he appears as senior author. (See Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride as fluoridating agents—A cost–benefit analysis and Corrigendum to “Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride as fluoridating agents—A cost–benefit analysis” [Environ. Sci. Policy 29 (2013) 81–86]“)

The “credibility” of his “expertise” on the subject is shown by the fact his second paper was necessary to correct the huge arithmetic mistake he made in the first paper!

Perhaps you can see why the Connett/Hirzy act brings Done Quixote and Sancho Panza to my mind.


The “report” is discredited even before addressing the arguments presented – simply because of the well-known anti-fluoride stance of all the authors and “peer-reviewers.” The diagrammatic network shows just how incestuous the “report” is. It is simply an attempt to put a “sciency” face on their political stand and their attack on the Royal Society Review.

As a scientific presentation it is a farce.

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November ’14 – NZ blogs sitemeter ranking



PLEASE NOTE: Sitemeter is still playing up but far fewer blogs are effected. It was still impossible to get the stats for a the blogs that I list below. Maybe more bloggers will shift to StatCounter or other counter.

No stats could be found for these blogs:

Works in progress This Mum Rocks
Weakly Whirled News Science Behind the Curtain
Two Minutes Sport Grumpollie
Wysiwygpurple’s Blog Louis’ Outlook
Stats Chat A conservative perspective
Webweaver’s world The Meaning of Trees

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 November 2014. 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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Severe dental fluorosis the real cause of IQ deficits?

A new study finds cognitive function defects, like IQ, in children are not significantly related to fluoride in drinking water. But they are associated with medium and severe dental fluorosis.

This interests me for two reasons:

  1. The report is by Choi and Grandjean who had also authored the 2012 meta-review often used by anti-fluoride activists to claim that community water fluoridation causes a lowering of IQ (the authors subsequently pointed out the high fluoride concentrations in the papers they reviewed meant that conclusion is not valid)
  2. The data reported is consistent with my suggestion in Confirmation blindness on the fluoride-IQ issue that reported relationships between IQ and drinking water fluoride concentration could really indicate a relationship with severe dental fluorosis, and not drinking water fluoride itself.

The new report is:

Choi, A. L., Zhang, Y., Sun, G., Bellinger, D., Wang, K., Yang, X. J., … Grandjean, P. (2014). Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study. Neurotoxicology and Teratology.

Firstly – this is only a pilot study and has several acknowledged weaknesses – the small number of children studied (51) being the most obvious. However, this is what was found:

“Sixty percent of the subjects examined had moderate or severe fluorosis. These children were exposed to elevated fluoride concentrations in drinking water. Children with normal or questionable Dean Index were all from households with a water fluoride concentration of 1 mg/L and had urinary fluoride excretion levels below 1 mg/L.”

The children were placed in 3 groups according to their degree of dental fluorosis:

  1. Normal/questionable (N=8)
  2. Very mild/mild (N=9)
  3. Moderate/severe (N=26)

The high proportion of children with moderate/sever dental fluorosis indicates the study involved an area of endemic fluorosis.

And the results of neuropsychological tests:

“Results of multiple regression models show that moderate and severe fluorosis was significantly associated with lower total and backward digit span scores when compared to the reference combined categories of normal and questionable fluorosis (Table 4). Although the associations between fluoride in urine and in drinking water with digit span were not significant, they were in the anticipated direction. Motor coordination and dexterity were not significantly associated with fluoride in drinking water and fluorosis although higher levels were associated with poorer scores as well. Other outcomes did not reveal any association with the fluoride exposure.”

The authors used a number of neuropsychological tests. The digit span test results suggest a “deficit in working memory” for the children with moderate and severe dental fluorosis. None of the other tests used show any signficant relationship with indices for fluoride exposure.

So, this pilot study did not show any association of neuropsychological tests with fluoride concentration in drinking water but it did find an association with medium and severe dental fluorosis. This is consistent with my speculation in Confirmation blindness on the fluoride-IQ issue that “a physical defect like dental and skeletal fluorosis could lead to decreasing IQ.”

I argued that:

“minor physical anomalies are known to be associated with learning difficulties and emotional illness in children (seeHilsheimer & Kurko 1979). It seems entirely reasonable that a physical anomaly like severe dental fluorosis could lead to learning difficulties in children which could be seen as lower IQ values.”

There are many problems with the studies anti-fluoride activists promote relating IQ to fluoride in drinking water. But it could be that any real effect seen with the higher fluoride concentrations could simply be explained by effects of the physical anomaly of medium and severe dental fluorosis common at these higher concentrations.

Unfortunately the authors of this study still do not consider this possibility. I guess it could be that someone with a hammer only sees nails, and chemical toxicologists are only capable of considering brain damage caused by toxic chemicals. The effects of physical anomalies on learning difficulties are probably quite outside their training and experience.

Their confirmation bias and mental blockage on this meant they were considering dental fluorosis as just another indicator of dietary fluoride intake. However, even that assumption has its problems because genetic differences are also known to be involved in dental fluorosis.

I think this must be why they ended with a conclusion that could well be quite unfounded:

“This pilot study in a community with stable lifetime fluoride exposures supports the notion that fluoride in drinking water may produce developmental neurotoxicity”

Dental fluorosis and community water fluoridation

Fluorosis is endemic in many parts of China and the high prevalence of medium/severe dental fluorosis (60%) among the children in the Choi et al (2014) pilot study shows their situation is not at all similar to that in areas of New Zealand and USA using community water fluoridation (CWF).

The figures below give some context.

Here are examples of the different degrees of dental fluorosis.

The graph below shows the situation reported for New Zealand in the 2009 New Zealand Oral health Survey (see Our Oral Health). No severe and only 2% moderate dental fluorosis reported.

This figure (taken from Fluorosis Facts: A Guide for Health Professionals) shows the amount  of moderate and severe dental fluorosis in the US is also very small.

Perhaps we can now contrast the situation here, in areas where CWF is common, with the situation in China in areas with endemic fluorosis where these studies were undertaken. The figure below is a slide from a presentation by Xiang (2014) to Paul Connett’s recent anti-fluoride “get-together” (Xiang 2014). This is not the very mild dental fluorosis attributed to CWF.

(Anti-fluoride people also often single out the study of Xiang, et al (2003). Effect of fluoride in drinking water on children’s intelligence. Fluoride, 36(2), 84–94, because unlike the others it is more detailed.  Xiang’s team has studied areas where fluorosis is endemic.)


Anti-fluoride activists often promote the meta-review of Choi et al (2012) in their arguments against CWF. However, there are many problems with these studies including the fact reported IQ effects were associated with much higher drinking water fluoride concentrations than occurs with CWF.

The new study of Choi et al (2014) did not confirm any association of neuropsychiatric measurements with drinking water fluoride concentration. However, it did show association of negative neuropsychological effects with medium/severe dental fluorosis.

This is consistent with the physical anomaly of severe dental fluorosis being the real cause of IQ effects and not any direct chemical toxic effect.

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Standing up to junk science in New Zealand

Last week we saw several local victories for science over pseudoscience. And the US mid-term elections also gave electoral victories supporting community water fluoridation in 5 out of 6 communities where it was voted on.*

Peter Griffin from New Zealand’s Science Media Centre reported on the New Zealand victories in his post Experts shine in fight against junk science.

“It was a week when climate change denial, a “miracle” ebola cure and homeopathy grabbed headlines.

But by and large it was also a week where the media laid out the evidence and featured expert commentary putting the science behind the claims in perspective.”

So, the media seemed to be “on-side” this time and scientific experts were fronting up to counter the pseudoscience.

“The pending arrival in New Zealand of Genesis II Church of Health and Healing leader James Humble to push his Miracle Mineral Solution (MMS) was front page news. Medsafe warned that the treatment acts like an industrial bleach and could cause serious harm to those who took it. Australia’s Nine News reported that four Victorians had been hospitalised after taking the MMS treatment.

Shaun Holt

Dr Shaun Holt

Natural remedies expert Dr Shaun Holt and University of Auckland microbiologist Dr. Siouxsie Wiles made numerous media appearances to explain the pseudoscience Humble has been spreading about MMS, including that it can cure Ebola, HIV and malaria.The Herald reported today that an Auckland man who attempted to attend one of the “non-religious” Church’s seminars in the Hauraki Plains, was removed when it emerged he had not paid the US$500 registration fee, a hint perhaps at the real reason behind Humble’s Australasian tour.”


NZ Herald’s front page piece on MMS

The latest report from the Intergovernmental Panel on Climate Change renewed the media interest in climate change.

“False balance in climate coverage

Professor Tim Naish and Dr James Renwick, who have both contributed to IPCC reports put the latest update in context for New Zealand on One News and 3 News.

However TVNZ undermined its own climate change coverage by featuring noted climate sceptic and energy sector consultant Bryan Leyland on the Breakfast show, including presenting a graph featuring data supplied by Leyland himself.

By the end of the day the item had been pulled from TVNZ’s website after the broadcaster received numerous complaints from the public, scientists, as well as journalists.”

Then there was the response to the Green Party’s natural products spokesman Steffan Browning’s folly in signing a petition calling for homeopathic treatments to be used in the fight against Ebola. This lead to his demotion within the party and removal of his spokesman role.

“The embarrassing endorsement attracted attention in the UK and the condemnation of Browning’s own caucus.

Writing on Sciblogs, Dr Grant Jacobs applauded Browning’s demotion, but pointed out that he retained other science-related shadow portfolios.

“I’m aware of a number of people who have said they didn’t vote for the Greens because of Steffan Browning’s stance on genetic engineering and others who have said that while they voted for the Greens they don’t approve of Browning’s approach to GMOs and GE.”

Peter Griffin finishes by thanking “all the scientists who stepped up to make sense of the dubious claims journalists and the public were faced with this week.”

I think this also shows what can be achieved when good science journalism is actively promoted by groups like the Science Media Centre, and when scientists and other experts  participate in the social communication media and make themselves available to journalists.

*Support for community water fluoridation in these 5 communities was pretty overwhelming:

Boyne City, Michigan – 68% support for fluoridation:
Bronson, Michigan – 63% support for fluoridation:
Kalama, Washington – 73% support for fluoridation:
Saline County, Kansas – 67% support for fluoridation:
Healdsburg, California – 68% support for fluoridation:

These victories were probably because fluoridation supporters, families and dentists organised public campaigns. See Group wants fluoride vote to keep its teeth.

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Fluoridation – a racist conspiracy?

Political activists campaigning on health issues often resort to scaremongering. This can be dangerous – especially when their stories have no real basis but rely on selective and distorted information.

Paul Connett’s Fluoride Action Network (FAN) often resorts to this sort of scaremongering. Now they are launching a series of stories dressed up as “exposès.”  The first is aimed at African-Americans and claims the US  “federal government has known for five decades that blacks were even more susceptible than whites to serious damage from fluoride added to water supplies, but it urged local governments to fluoridate the population anyway.”

Typically, Connett’s Crowd is promoting this campaign through FAN press releases which get picked up by “natural” health magazines and web pages. The articles are then heavily promoted throughout social media by activists – sometimes even making their way into the mass media (see Gov’t Failed to Warn about Fluoride’s Disproportionate Harm to Black Community and Feds: Blacks Suffer Most From Fluoride, Fluoridate Anyway).

The press release is summed up in the first paragraph:

“Government health authorities knew over 50 years ago that black Americans suffered greater harm from fluoridation, yet failed to warn the black community about their disproportionate risk, according to documents obtained by the Fluoride Action Network (FAN).”

So the evidence, the “document,” on which they hang this story, is a memo.


Now, that is very pathetic to hang a campaign on, isn’t it. And the campaigners are also relying on the false idea that anything obtained via freedom of information inquiry must have been “secret” or “hidden” from the public eyes. (Incidentally they do the same with the Certificates of Analysis for fluoridation chemicals used by water treatment plants – even appearing to think that listing an analytical result for contaminants, however small, is somehow “proof” that the contamination is a problem – see Fluoridation: emotionally misrepresenting contamination and Natural News comes out with a load of heavy metal rubbish on fluoride).

Differences in dental fluorosis prevalence not hidden

But the scientific information comparing prevalence of dental fluorosis among US whites and African-Americans is neither new or hidden. In fact, FAN’s press release does refer to a little of this published data, but again typically they distort it.

In particular it uses data from studies where fluoride in drinking water were often higher than the optimum levels for community water fluoridation (CWF). Consequently the studies include some people exhibiting the medium and severe forms of dental fluorosis never observed with CWF.

One of the papers cited is Martinez-Mier, E. A., & Soto-Rojas, A. E. (2010). Differences in exposure and biological markers of fluoride among White and African American children. Journal of Public Health Dentistry, 70(3), 234–40. It did report higher amounts of dental fluorosis in the African-American children they studied. But it also found that the African-American children in the study reported using larger amounts of toothpaste and had higher urine fluoride concentrations than white children. It concluded:

“Differences in fluoride exposure between two racial groups were observed. These differences are complex and need to be better defined.”

This does not warrant claims of  African-Americans being more susceptible than whites. Nor is the information “explosive” as the FAN press release claims.

Another study cited was Williams, J. E., & Zwemer, J. D. (1990). Community Water Fluoride Levels, Preschool Dietary Patterns, and the Occurrence of Fluoride Enamel Opacities. Journal of Public Health Dentistry, 50(4), 276–281. But the study actually doesn’t back up the FAN claims as these authors found:

“higher TSIF scores [an index of dental fluorosis prevalence] were associated with city children significantly more than with county children. There was no association of TSIF scores either in the city children or the county children with respect to gender, race, preschool dietary patterns, or dentifrice ingestion.”

Another cited paper is Butler, W. J., Segreto, V., & Collins, E. (1985). Prevalence of dental mottling in school-aged lifetime residents of 16 Texas communities.  American Journal of Public Health, 75(12), 1408–1412. These authors found “children who were White or had a Spanish surname had about the same prevalence of mottling while Blacks had a higher prevalence.” This appears to support the FAN claim but air conditioning in the children’s home and total dissolved solids and zinc in the drinking water also influenced prevalence of mottling. Significant mottling only occurred where  drinking water fluoride concentrations were over 2 ppm making the conclusions irrelevant to CWF where concentrations are usually in the range 0.7 to 1 ppm

Finally, they cite Beltrán-Aguilar, E. D. ., & Gooch, B. F. ; (n.d.). Surveillance for Dental Caries, Dental Sealants, Tooth Retention, Edentulism, and Enamel Fluorosis — United States, 1988–1994 and 1999–2002. Yes, this study did show African American had a slightly higher prevalence of very mild and mild dental fluorosis, as the figure below shows.


They did not advance an explanation for this but note that “different hypotheses have been proposed, including biologic susceptibility or greater fluoride intake.” One could also suggest differences in residential location – especially as some of the people in the study had moderate or severe dental fluorosis indicating they were likely consuming drinking water with a fluoride content above the level recommended for CWF.

But we could make the same comparisons with tooth decay data from this study (see figure below):


Perhaps we should be jumping up and down about the increased racial sensitivity of African-Americans and Mexican Americans to the disease of tooth decay and claim that this information has been suppressed or nothing done about the problem.

Or perhaps, as is most likely happening, authorities are just getting on with the job of working out how to deal with health inequalities in different ethnic groups.


This campaign is just another of the scaremongering attempts of Connett’s crowd. Appealing to conspiracy theorists it uses a memo obtained as part of a freedom of information inquiry to imply a cover-up. The campaing cites studies which do show real differences but do not show they result from differences in sensitivity. And they are not large enough to justify the extreme language of the press release and reports.

Of course there may be similarities in the dental health conditions of disadvantaged ethnic groups in the US, and in New Zealand and Australia, but the way some anti-fluoride propagandists have used these press releases to “prove” that NZ Maori and Australian Aborigine are adversely effected by CWF borders on naive racism.

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September ’14 – NZ blogs sitemeter ranking


PLEASE NOTE: Sitemeter is playing up again making it impossible to automatically get the stats for some blogs – those I list below. Maybe more bloggers will shift to StatCounter or other counter.

No stats could be found for these blogs:

Works in progress Sportsfreak
Weakly Whirled News Infectious thoughts
Two Minutes Sport Science Behind the Curtain
Wysiwygpurple’s Blog Grumpollie
Stats Chat Louis’ Outlook
Webweaver’s world West City Darts
Social Media and the 2014 General Election A conservative perspective
Love your work Save our schools NZ
Today is my birthday The Meaning of Trees
This Mum Rocks

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 September 2014. 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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Peer review of an anti-fluoride “peer review”

In  Anti-fluoride activists define kangaroo court as “independent” I promised to review the anti-fluoridationist International Peer Review.” This is Anti-fluoride  critique of 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).

So here is my peer review, of a review, of a review.

General comments

Anti-fluoride activists have  busily mentioned all the apparent contributors to this critique but I will only deal with Kathleen Theissen’s and Chris Neurath’s comments as only these have any substance.  James Beck declined comment saying only “On the current New Zealand case I don’t think I can do any better than Chris has done.” Similarly Speeding Micklem says only that “Chris’s analysis is excellent.”

Hardy Limeback does not engage at all with the science in the Royal Society Review, but does express his emotional attitude towards it. He says:

“I can’t be bothered to show step by step where this review does not meet the standards of critical scientific analysis. . . . Chris is right on the ball in critiquing this review. I’m not sure many people will appreciate just how detailed he is.
I’m disgusted by how sloppy the NZ reviewers were. They were obviously politically motivated.”

However, Limeback’s comment on the use they will make of their critique is interesting:

“The effort to critiquing every paragraph of the NZ review is taxing but once it is done and posted on the website, it would be most useful for those people who want to take on the promoters of fluoridation who will undoubtedly use this review to support the profluoridation agenda and point to how unscientific, one-sided, politically motivated this review really is.
I would be happy to lend my name to the list of scientific reviewers of this critique.”

So, you can get an idea of what their purpose is in their “peer review.”

Now, the specific issues raised in Theissen and Neurath’s comments.

Margin of safety

The Royal Society Review found some population groups may exceed the prescribed “safe” levels of F intake. So Theissen concludes that “the fluoride concentration in drinking water is too high and should be lowered.” However, she ignores completely the review’s comments on this issue.

“Infants 0-6 months of age who are exclusively fed formula reconstituted with fluoridated water will have intakes at or exceeding the upper end of the recommended range (UL; 0.7 mg/day). The higher intakes may help strengthen the developing teeth against future decay, but are also associated with a slightly increased risk of very mild or mild dental fluorosis. This risk is considered to be very low, and recommendations from several authoritative groups support the safety of reconstituting infant formula with fluoridated water.”

The review also noted that children from 1 – 4 yrs old do not exceed recommended levels on F intake but intake from ingested toothpaste my increase intake above recommended levels. It goes on to conclude:

“Consumption of fluoridated water is highly recommended for young children, as is the use of fluoride toothpaste (regular strength – at least 1000ppm), but only a smear of toothpaste should be used, and children should be supervised during toothbrushing to ensure that toothpaste is not swallowed/eaten.”

I also discussed the issue of risk for formula-fed infants in my article When politicians and bureaucrats decide the science  and in my exchange with Paul Connett. Here I note how “peace of mind” advice to those parents who may be concerned about increased risk of dental fluorosis gets presented by anti-fluoride people as safety warnings.

Adequacy of standards for fluoride intake

Theissen discusses the adequacy of a stands for F intake at length but her only beef with the Royal Society Review on this appears to be that it doesn’t challenge existing standards. She herself considers that these standards should be revised to “obtained values much lower than those currently considers desirable by the New Zealand government.” But here she is promoting a personal agenda and not objectively critiquing the Royal Society Review.

Effects of community water fluoridation (CWF) in NZ

Theissen considers that the NZ review offered “little documentation for the beneficial effects of fluoride.” Strange – has she read the review? Table A2 lists 21 major reviews it considered and 7 New Zealand sources were included – the 2009 NZ Oral Health Survey and regional studies in Otago, Southland, Canterbury, Wellington, Auckland and Northland.

If that was insufficient for Theissen then why is her only counter to mention John Coulquhoun’s reminiscences in his article of 1997? It is not enough for Theissen to use his assertions “that there are virtually no differences in tooth decay rates related to fluoridation” and “25 percent of children had dental fluorosis.” But has she bothered to check out his data at all critically? Why no more citations supporting her  claim?

Coulquoun was a committed anti-fluoridationist  and a critical check of his claims show them to be unreliable. Here is a sentence from the abstract of his paper Colquhon 1985:

“In the unfluoridated areas all the children, and in the fluoridated areas only selected children, had received regular topical fluoride treatments.” And he concluded “When the socioeconomic variable is allowed for, child dental health appears to be better in the unfluoridated areas.”

Apart from the wishful thinking displayed in his interpretation of a statistically non-significant difference he has glossed over the fact that both fluoridated and unfluoridated groups were receiving fluoride treatments of one sort or another!

Similarly, Theissen puts more trust in Colquhoun’s brief comment on dental fluorsis than the several  pages on this subject in the review. Anti-fluoride propagandists are continually misrepresenting dental fluorosis data to imply any extremely mild forms attributable to fluoridation should be treated like the severe forms which are not caused by fluoridation. The Royal Society review’s comment on the aesthetic effects help bring some context back on this issue:

“It is important to note that the seemingly high prevalence of fluorosis reported in some studies and systematic reviews includes mainly mild and very mild (and sometimes questionable) degrees of fluorosis, with only a small proportion that would be considered to be of aesthetic concern.

Surveys have shown that very mild to mild dental fluorosis is not associated with negative impact on perception of oral health,[142] and that adolescents actually preferred the whiteness associated with mild fluorosis.[143] In a recent study, adolescents answered a questionnaire regarding the impact of enamel fluorosis on dental aesthetics, older adolescents rated photographs of mild fluorosis more favorably than younger ones. A fluorosis score indicative of moderate fluorosis was the level considered to have aesthetic significance. Carious teeth were rated significantly lower than fluorosed teeth.[144]

Carcinogenicity and genotoxicity

Theissen, like almost all anti-fluoride propagandists, relies completely on the  the Bassin et al (2006) study for evidence here and ignores later studies which did not confirm Bassin’s work. In my exchange with Connett I criticised him for the same tactic (see Fluoride debate: Final article – Ken Perrott):

“the importance Paul gives to a single study on fluoride and osteosarcoma illustrates his mechanical and selective approach to “weight of evidence.” He has not bothered including either the study by Comber et al (2011) of this issue in Ireland or the study by Levy & Leclerc (2012) for the US. Possibly because both of these concluded that water fluoridation has no influence on osteosarcoma incidence rates.”

So while Theissen is upset the Review “dismisses” Bassin’s work, this is not the “out of hand” rejection she implies. The Review says:

“The few studies that have suggested a cancer link with CWF suffer from poor methodology and/or errors in analysis. Multiple thorough systematic reviews conducted between 2000 and 2011 all concluded that based on the best available evidence, fluoride (at any level) could not be classified as carcinogenic in humans. More recent studies, including a large and detailed study in the UK in 2014, have not changed this conclusion. “


I partially agree with Neurath’s charge on the inadequacy of the Royal Society’s comment on the standardised weighted mean difference in IQ scores discussed by Choi at al (2012). Some people have made a lot of the confusion around this issue. I would like someone with good statistical skills to comment on the risks involved in making such an analysis in a meta study where there is no conformity of experimental design or treatment in the individual studies.  Wikipedia lists a number of pitfalls in statistical meta analysis, two of which seem particularly relevant here – publication bias and agenda-driven bias. In my article Quality and selection counts in fluoride research I described how the studies used had been selected and it is hard not to see an agenda behind this. So, I do think Choi et al’s statistical analysis is questionable.

However,  this issue is irrelevant to CWF because of the generally high drinking water fluoride concentrations used in these studies. Theissen and Neurath resort to the special pleading in their efforts to avoid that problem.

Theissen stressed that in the Choi et al review “One study had “high” at 0.88 mg/L, quite relevant to CWF.” Neurath says “In fact, one of the Chinese IQ studies had an average water concentration of 0.88 mgL in the high exposure group.”

At first sight this seems relevant to CWF and Paul Connett, like many anti-fluoride activists, stress this study in defending the relevance of Choi et al (2012). Strange then that none of them actually discuss the study details. Perhaps we should.

The study is a one and a half pages newsletter report:

Lin et al (1991). The relationship of of low-iodine and high-fluoride environment to subclinical cretinism in Xinjiang. Iodine Deficiency Disorder Newsletter, 24–25.

It has few of the details we normally expect in scientific papers. For example, I would like to know what the range of fluoride concentrations was in the drinking water, what other dietary intake occurred, how was the “dental fluorosis” observed defined, etc.

Children from low iodine areas were compared with a group from another area that had received iodine supplementation. About 15% of the children suffered mental retardation, 69% of these exhibited subclinical endemic cretinism. The effect of iodine supplementation was clear, the effect of fluoride not so clear. But anyway, hardly a report to hang any conclusion on about CWF in New Zealand.

They also resorted to special pleading to downplay other problems with these studies:


“the one study . .  that did not show lower IQ still showed a tendency in that direction (just not statistically significant) and it certianly did not show clear absence of any effect”

“While some of the neurotixicity studies did not address confounders, some did handle them responsibly” [Most of them didn’t]


“most of the studies did consider other sources of exposure such as from food dried over coal fires . . . This in almost all studies, major alternative sources of fluoride exposure were ruled out or controlled for” ”  – [In fact they weren’t as most didn’t consider other inputs]

“several of the studies did consider each of these potentially confounding factors, and at least one group of researchers (lead by Xiang) considered all of them and more.” [yes, one – “all and more” – but why not consider Xiang in detail then? Why try to spread his thoroughness throughout all these meagre studies?

“simply failing to assess these factors in a study does not mean the study was confounded and produced invalid results.” [well no, but isn’t it best to check known confounders?]


“Connett’s get-together” – 5th FAN Conference, Sept 6-8, 2014. Credit: Photo by Corey Sturmer,

Anti-fluoride people also often single out the study of Xiang, et al (2003). Effect of fluoride in drinking water on children’s intelligence. Fluoride, 36(2), 84–94, because unlike the others it is more detailed.  Xiang’s team has studied areas where fluorosis is endemic. Here is a slide from his presentation  to Paul Connett’s recent anti-fluoride “get-together” (Xiang 2014). This is not the very mild dental fluorosis attributed to CWF.

xiang-Endemic fluorosis

Now I think severe dental fluorosis like this would create learning difficulties for children in the same way dental decay does (Seirawan et al 2012). I suggested this in Confirmation blindness on the fluoride-IQ issuePresumably Xiang could have analysed his data to check if the apparent IQ drop was correlated with the prevalence of dental fluorosis. I would think that could be an obvious first step.

Theissen  berates the Royal Society review for suggesting there is no plausible mechanism for the effect of F on IQ. Instead she resorts to special pleading again – admitting “no mechanism has been established,” attributing that to lack of research, not the absence of a mechanism. And then speculating on possible mechanism related to thyroid function, etc. The trouble is that this sort of special pleading can soon convert logical possibilities into established proof in the minds of the faithful. And meanwhile an obvious possible cause of the IQ data may be staring her in the face but she is oblivious because it does not involve “brain damage.”

Animal studies

Theissen rejects the Royal Society’s dismissal of results from animal studies because of the high concentrations used in them. She says baldly “animals require much higher exposures (5-20 times higher, or more; see NRC 2006; 2009). But what does NRC 2006 actually say (The NRC 2009 simply references NRC 2006)? It discussed the contradictory data used for attempting to show a ratio between humans and rats for blood plasma levels and concluded:

“Dunipace et al. (1995) concluded that rats require about five times greater water concentrations than humans to reach the same plasma concentration. That factor appears uncertain, in part because the ratio can change with age or length of exposure. In addition, this approach compares water concentrations, not dose. Plasma levels can also vary considerably both between people and in the same person over time (Ekstrand 1978).”

Again Theissen resorts to special pleading converting a vague possibility into an established “fact” in an effort to justify the unquestioned use of animal studies using high concentrations.

Mullinex et al (1995) also attempted to justify use of similar animal studies by comparison of blood plasma F levels. However, there is a huge range and variability in these levels so extremely easy to make subjective justification. I am suspicious of such speculation.

While I am happy to  acknowledge that it may be too simple to equate the effects for humans and animals at the same intakes, I think Theissen’s assertion “animals require much higher exposures” is straw-clutching. Millunex et al (1995) exhibited the same straw-clutching when she asserted plasma levels in her rats were similar to those in “humans exposed to high levels of fluoride.” Anti-fluoride activists love to quote Mullinex while ignore or downplaying the word “high.” She was quoting plasma F concentrations for children receiving 5 – 10, and 16 mg/L F, 10 or 20 times higher than used in CWF! But the huge effect of treatment time on plasma F concentration in rats must surely warn any objective reader to be very careful about these sort of claims. (Rats receiving 125 ppm F had plasma concentrations of about 0.1 mg/L after 6 weeks exposure but 0.64 ± 0.31  mg/L after 20 weeks).

Endrocrine effects

Theissen appears not to have properly read this section of the Royal Society Review.

Contrary to her assertion it does refer to the NRC discussion of these effects and comments:

“Most of the reviewed animal studies were designed to ascertain whether certain effects occurred, and not to determine the lowest exposures at which they occurred. The report concluded that fluoride (at unspecified levels) can affect normal endocrine function or response, and that better characterisation of fluoride exposure in humans in epidemiological studies is needed to investigate the potential endocrine effects of fluoride.”

It acknowledges potential effects (at unspecified levels) despite Theissen’s claim it “failed to mention” them. However, at this time no such effects have been observed in humans at the concentrations used in CWF. So the Review summarises its findings this way:

“A number of other alleged effects of CWF on health outcomes have been reviewed, including effects on reproduction, endocrine function, cardiovascular and renal effects, and effects on the immune system. The most reliable and valid evidence to date for all of these effects indicates that fluoride in levels used for CWF does not pose appreciable risks of harm to human health.”


The Royal Society Review evaluated current scientific knowledge on health effects of fluoridation. It was requested by the Auckland Council on behalf of several local Councils. They wanted a review of the scientific evidence for and against the efficacy and safety of fluoridation of public water supplies. This requirement arose from the recent campaigns by anti-fluoridation activists who targeted individual councils with a barrage of misinformation.

We should understand that the size and accessibility of the Review is aimed at informing public decision-making on the issue.  For this reason it also deals with New Zealand aspects. It is not meant to be as extensive and detailed as the 530 page US National Research Council report.

Hopefully any future consideration of community water fluoridation by local body councils will be better informed because of the Royal Society review. In particular it should help counter the sort of misinformation that has confused some councils in the past.


Colquhoun, J. (1985). Influence of social class and fluoridation on child dental health. Community Dentistry and Oral Epidemiology, 13(1), 37–41.

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.

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.

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The information war – The NZ Listener takes up arms

First – have a look at this satirical programme from Germany. It has English captions but is worth watching a few times for the subtleties.

I have commented before about the information war going on around the Ukrainian conflict. It might seem like a distant issue here (and it usually doesn’t get much coverage). But I believe the biassed propaganda we are exposed to is dangerous because of its jingoism.

And this week the NZ Listener brought the conflict right into our living rooms with an editorial which uses the same innuendo and unconfirmed claims that feeds this jingoism (see Alarmed World).

Out of the blue in a piece seeming to be about Islamic State and the conflict in the Middle East we get this:

The West faces a similar test of its resolve in Ukraine, where attempts to deter Russian-backed aggression have been largely ineffectual. The world knows that Russia supports the separatist rebellion in eastern Ukraine, that it has troops on Ukrainian soil and that it probably supplied the missiles that brought down a Malaysian airliner. Yet the European Union’s sanctions against Russia have succeeded only in provoking economic counter-measures that have hurt European food producers, for whom Russia was a $19 billion export market, and threats to ban “unfriendly” airlines from Russian airspace.

The assertion the “world knows” has become a substitute for evidence! The world certainly knew when the USSR invaded Hungary and Czechoslovakia, or the US invaded Iraq. We could see the evidence. Tanks surging across borders, planes bombing, troops on the ground. But nothing of that here (except the occasional soldier who claims to have lost his way – or fuzzy satellite photos of combine harvesters*).

[Yes, I know the presence in Ukraine of Russian and other voluntary (or even mercenary) fighters is well established – fighting on both sides. But that is not the same as invasion of a foreign army the media often claims.]

The “world knows” that Russia “probably” supplied missiles used to shoot down Malaysian airline MH17 – when the world knows nothing of the sort! At this stage this issue is wide open (see MH17 – Preliminary report leaves most conspiracy theories intact) – but it seems our media thinks we don’t deserve anything better than unwarranted claims on such a serious matter.

That shows no respect for the victims of this tragedy.

As for the danger of this sort of biased reporting and media manipulation, and the jingoism it promotes, we can read the last paragraph in the Listener editorial.

“What has become painfully apparent, in both the Middle East and Ukraine, is that the democratic West is susceptible to paralysis and self-doubt when confronted with the forces of totalitarianism and autocracy. Perhaps it’s time to consider what the world’s fate might have been without the moral resolve exhibited by Churchill and Roosevelt in World War II.”

Isn’t this the sort of talk used to prepare a population for war?


* Of course I have taken poetic license here about these fuzzy photos. After all,  whether these were photos of artillary or combine harvesters is not evidence for or against an invasion. We know that both sides in Ukraine have plenty of artillery weapons and are using them. But for the pedantic, and those confused by my aside, here are some links to the combine harvester/artillery story:

Dave Lindorff writes about it in his article Satellite Images of Alleged Russian Artillery in Ukraine Come A-Cropper. He produced this photo below:


And commented:

“In the ongoing propaganda campaign mounted by the Obama administration to claim that Russia has “invaded” Ukraine from the east, it offered up some grainy black-and-white satellite images purporting to show heavy Russian military equipment inside Ukraine.

I earlier noted how unlikely it was that heavy mobile artillery pieces would be set up in a perfect line in what appeared to be a field of crops, with, as the government claimed, cannons aimed towards Ukrainian positions in toward the west. As I pointed out, there was no sign of piles of ammunition alongside these “units” as we routinely see in closeups of heavy mobile artillery — for example in photos of IDF pieces positioned outside of Gaza. I also noted the unlikelihood that such equipment would have been set up in an open field, unprotected by trees or other cover, and lined up to make for easy targeting by enemy artillery or air attack.

Now an alert reader from the agricultural state of Texas (Laredo, TX to be precise), has sent a note suggesting out that what the supposedly incriminating images most likely show are combines in a field of grain or some other crop planted in rows. He sent along photos showing harvesters, which of course feature a long, straight “cannon-like” tube which is used to shoot the harvested grain up and into an accompanying truck to be hauled off to market or to a storage silo.”

Here is a higher resolution of the satellite photo which, I understand, came from the US State Department:


(from European Union Court of Justice Imposes Anti-Rasmussen Rule – Sanctions Cannot Be Imposed by Reason of Fabrication, Lies, Dissimulation)

I wouldn’t pretend to draw any definite conclusions from these photos but I think Dave Lindorff  has a point:

“Now maybe the released satellite images do show Russian artillery, but given Washington’s extensive history of abject lying in the interest of promoting its war agenda (think Gulf of Tonkin, Iraq WMDs and mobile poison gas factories, Assad gas attacks in Damascus, etc.), it’s worth taking the claim with a “grain” of…well, in this case actual grain.”

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Activist’s anti-science adverts found misleading – again

The activist Fluoride Free NZ (FFNZ) organisation have had a bad year with the Advertising Standards Authority (ASA). They have had half a dozen complaints against them for misleading advertising upheld.

The latest complaint referred to FFNZ’s adverts for a meeting they organised in Rotorua last July. This advert claimed

“Informed Doctors and Dentists say:
Keep Rotorua’s water safe. It’s our right to choose.
Swallowing Fluoride

Is unsafe for babies
Doesn’t protect teeth
Can cause harm.”

The complaint basically was that these claims were presented as matters of fact, rather than opinion. And the declarations of harm, danger to babies and lack of effectiveness protecting teeth were effectively claims implying scientific  substantiation. It also raised the issue of misrepresentation of the views of New Zealand doctors and dentists – implying that the claims are supported by a majority of these professional when they aren’t. Quite the opposite.

In fact, FFNZ can get only about half a dozen such professionals willing to promote their message. It is dishonest to then use these handful of mavericks to imply the whole profession supports the anti-fluoride claims.

The complainant also pointed out the advert was effectively indulging in scaremongering because it claimed there was harm, when there wasn’t any, and it appeared to be promoting the advice of professionals, when professionals weren’t saying what was claimed.

The ASA ruling concludes:

“The Complaints Board said the advertisement was likely to mislead as the claims were presented as facts, but were not substantiated by the Advertiser, in breach of Basic Principle 3 and Rule 2 and was not saved by advocacy, in breach of Rule 11 of the Code of Ethics. It said the advertisement unjustifiably played on fear, in breach of Rule 6 of the Code of Ethics and was socially irresponsible in breach Basic Principle 4 of the Code of Ethics and the Complaints Board ruled the matter was upheld.

It is good to see more people coming forward to make these sort of complaints. The anti-science lobby has been getting away with this sort of misrepresentation for years. Hopefully the experience of the ASA upholding such complaints will embarrass organisation like this to be more careful in their advertising.

In many cases all it takes is a simple sentence to clarify the advert is presenting the viewpoint or belief  of the advertiser, rather than scientifically established facts.