Tag Archives: Water fluoridation controversy

Cyber bullying of science

cyberbullyingI am always amazed at how easily public discussion about scientific issues can degenerate into childish and nasty attacks on science, and scientists. This is especially true for internet discussion – this medium really does seem to bring out the worst in some people.

Over the last few years we have seen climate science, and climate scientists treated this way. I have always tried to support that science, and those scientists, from afar and never thought I would become a victim of such nastiness myself.

Then I got involved in the fluoridation issue.

I am not critical of everyone who opposes fluoridation – some of my best friends oppose it. I can understand why some people will advocate personal freedom over social good. I can even understand the chemophobia and other misunderstanding which can make the less scientifically literate person a bit wary of fluoridation.

Anti-fluoridationists – a strange social mixture

But the anti-fluoridationists are a strange social mixture. Amongst the well-meaning environmentalists and health advocates there are some really irrational people. Conspiracy theorists are common. Some are concerned about chemtrails, others about Agenda 21 and attempts by the UN to control birth rates! Then there are the right-wing extremists, supporters of the US Tea Party Republicans, absolutely opposed to any community measure for social good.

The anti-fluoridation movement is a strange mixture of left and right, concerned greenies and outright libertarians. One wonders what would happen to these groups if the fluoride issue disappeared and internal strife broke out.

Unfortunately, it seems that quite often in the current controversy the more extreme conspiracy theorists and anti-science elements seem to be making the running. Speaking and acting for the more genuine members of the anti-fluoridation groups.

Internet bullying

I thought this only happened with teenage schoolgirls, or young female celebrities, but now find that even someone my age can become a victim. This video demonstrates the sort of attacks people who speak out about the science underpinning fluoridation can be exposed to. It really does put into context the decisions by local Health Boards not to participate in political meetings on fluoridation because of threats to, and attacks on, their staff.


In a way, this sort of bullying is a bit of a compliment. Perhaps I have done something right to have upset these anti-science extremists. But it is not about me. This sort of thing illustrates the sort of nasty hysterical anti-science propoganda out there on the internet. The worrying thing is that this guy actually does have a following (about 9500 subscribers to his YouTube channel). When I expressed ignorance of who he is one commenter told me that “everyone” in Australia and New Zealand has heard of him!

Yeah, right. But he is obviously popular with a certian group of people.

Image credit: uknowkids 

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
Fluoridate our water Facebook page
New Zealanders for fluoridation Facebook page

Fluoridation: the hip fracture deception

Warning – this book is deceptive

One of the myths promoted by the anti-fluoride people is that fluoridation is bad for our bones. As with similar myths the evidence used to support the claims usually comes from studies of situations where people have high F intake, often from natural sources.

However, there are studies which anti-fluoridationists can quote which do relate to fluoridated water concentrations.  For example, this is one of the many claims made by Christopher Bryson in his book The Fluoride Deception. This book tends to be used as scripture by anti-fluoridationists today so I thought I would look a bit more deeply into his claim.

Such deeper looks can often show problems of confirmation bias or uncritical evaluation of the literature – it did in this case.


Bryson based his claim solely on work by Joseph Lyon, in particular the paper Hip Fractures and Fluoridation in Utah’s Elderly Population by Christa Danielson; Joseph L. Lyon; Marlene Egger; and Gerald K. Goodenough (1992). However, he does claim  “subsequent studies have found similar associations between fluoride in water and bone fractures.”

Danielson et al. concluded:

“We found a small but significant increase in the risk of hip fracture in both men and women exposed to artificial fluoridation at 1 ppm, suggesting that low levels of fluoride may increase the risk of hip fracture in the elderly”


Well, it doesn’t take much searching to find papers with contrary conclusions. For example Community water fluoridation, bone mineral density, and fractures: prospective study of effects in older women by
Kathy R Phipps, Eric S Orwoll, Jill D Mason, Jane A Cauley (2000).

They concluded:

“Long term exposure to fluoridated drinking water does not increase the risk of fracture.”

So different conclusions, but why? Well Phipps et al. allude to the causes of contradictory conclusions in their introduction.

“While the benefit of fluoridation in the prevention of dental caries has been overwhelmingly substanti­ated, the effect of fluoridation on bone mineral density and rates of fracture is inconsistent. Ecological studies that compare rates of fracture specific for age and sex between fluoridated and non­fluoridated communities have variously found that exposure to fluoridated water increases the risk of hip fracture, (here they refer to Danielson et al 1992) increases the risk of proximal humerus and distal forearm fracture, has no effect on fracture risk, and decreases the risk of hip fracture. Ecological studies, however, have a major design flaw—they are based on community level data and cannot control for confounding variables at the individual level.” (My emphasis).

In contrast:

“We determined, on an individual level, whether older women with long term exposure to fluoridated water had different bone mass and rates of fracture compared with women with no exposure.” (My emphasis).

And they concluded:

“This is the first prospective study with adequate power to examine the risk of specific fractures associated with fluoride on an individual rather than a community basis. Our results show that long term exposure to fluoridation may reduce the risk of fractures of the hip and vertebrae in older white women. Because the bur­den of osteoporosis is largely due to fractures of the hip, this finding may have enormous importance for public health. If fluoridation does reduce the risk of hip fracture it may be one of the most cost effective meth­ods for reducing the incidence of fractures related to osteoporosis. In addition, our results support the safety of fluoridation as a public health measure for the con­trol of dental caries.”

So, if we compare the results from the two studies we see that while Danielson et al (1992) reported an increase in the risk of hip fracture for women drinking fluoridated water, Phipps et al (2000) actually reported a decrease in the risk. The difference being that Phipps et al (2000) removed confounding factors such as  medical history, drugs and supplements, reproductive history, menopause, alcohol consumption, exercise, smoking, caffeine intake, height and weight.


Relative risk of hip fracture for women with fluoride exposure compared to women with no fluoride exposure


While preparing this I noted a new paper on this subject just published – Näsman et al (2013) “Estimated Drinking Water Fluoride Exposure and Risk of Hip Fracture:A Cohort Study

The abstract reports:

“Estimated individual drinking water fluoride exposure was stratified into 4 categories: very low, < 0.3 mg/L; low, 0.3 to 0.69 mg/L; medium, 0.7 to 1.49 mg/L; and high, ≥ 1.5 mg/L. Overall, we found no association between chronic fluoride exposure and the occurrence of hip fracture. . . . fluoride exposure from drinking water does not seem to have any important effects on the risk of hip fracture, in the investigated exposure range.”

So extra support for the conclusion that fluoridation does not lead to increased risk of hip fracture.

Motivated cherry picking

I think this shows the danger of cherry picking studies to support a preconceived position. And of relying on individual sources, or ideologically motivated sources like  The Fluoride Deception, for information.

There is a large amount of research on fluoride which to the uninitiated must seem contradictory. Proper review of this literature requires skills in critical thinking, and background in the field. The sort of thing that activist groups, and local body councils, don’t have.

Of course, I have no special background in this area either – and I don’t pretend that my summary here is at all definitive. However, it does show how misinformation can easily be promoted, with an apparent respectability conferred by  scientific references, when motivated people cherry pick.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
Fluoridate our water Facebook page
New Zealanders for fluoridation Facebook page

Fluoridation – the IQ myth

fluoride_kills_test (1)Some of the myths promoted by anti-fluoridation activists really are of the “unsinkable rubber duck” variety. No matter how many times they are debunked they keep being repeated.

If you follow the fluoridation debate at all you will have come across the “Harvard Study” “proving” fluoride makes you dumb. It is often associated with the claim that the Nazis used fluoridated water supplies in their concentration camps to distract the inmates. Some will even claim that this is the purpose for fluoridation in the US!

I haven’t dealt with this particular myth yet, but really can’t do better than repeat this post from the US Life is Better with Teeth web site. (By the way, this is an excellent source of information on the fluoridation issue). The article is Fluoride and IQs

In July 2012, anti-fluoride activists circulated an article from a journal called Environmental Health Perspectives (EHP) to support their claim that fluoride lowers IQ scores in children. There are several reasons why the claim being made by opponents lacks credibility.

  • The EHP article reviewed studies on IQ scores for children living in areas of China, Mongolia and Iran where the water supplies have unusually high, natural fluoride levels. In many cases, the high-fluoride areas were significantly higher than the levels used to fluoridate public water systems in the U.S. In fact, the high-fluoride areas in these countries reached levels as high as 11.5 mg/L — more than 10 times higher than the optimal level used in the U.S.
  • This article offers a meta-analysis, and its credibility hinges on whether good-quality studies are reviewed. Yet the article’s co-authors admit that “each of the [studies] reviewed had deficiencies, in some cases rather serious, which limit the conclusions that can be drawn.” Although the studies compared high-fluoride with low-fluoride areas, the authors acknowledge that “the actual exposures of the individual children are not known.”
  • The two Harvard researchers who reviewed these studies have distanced themselves from the way in which anti-fluoride activists have misrepresented their article. After contacting these researchers, the Wichita Eagle newspaper reported, “While the studies the Harvard team reviewed did indicate that very high levels of fluoride could be linked to lower IQs among schoolchildren, the data is not particularly applicable here because it came from foreign sources where fluoride levels are multiple times higher than they are in American tap water.”
  • The Harvard researchers wrote in their article that the average standardized mean difference (0.45) in IQ scores “may be within the measurement error of IQ testing.” Despite web pages claiming that the article ”confirms” that fluoride reduces IQ scores, the Harvard co-authors did not reach a firm conclusion, writing instead that “our results support the possibility of adverse effects …” Indeed, their article called for more and better-quality research, including more “precise” data on the children involved and assurances that other factors have been ruled out as reasons for the IQ differences.
  • Given the small difference in IQ scores, it’s possible that arsenic levels, school quality, nutrition, parents’ educational levels or other factors could have shaped the results. The authors also added that “reports of lead concentrations in the study villages in China were not available”— another factor that could not be ruled out. A Britishresearch team reviewed similar Chinese studies, found “basic errors” in them, and reported that “water supplies may be contaminated with other chemicals such as arsenic, which may affect IQ.”
  • Between the 1940s and the 1990s, the average IQ scores of Americans improved 15 points.  This gain (approximately 3 IQ points per decade) came during the same period when fluoridation steadily expanded to serve millions and millions of additional Americans.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
Fluoridate our water Facebook page
New Zealanders for fluoridation Facebook page

When politicians and bureaucrats decide the science

The current seperation of responsibility for water treatment (local body councils) and community health policy (District Health Boards) is a problem when considering fluoridation. This was illustrated by the Hamilton City Council’s suspension of  fluoridation of the city’s water supply. In the end the City Council neglected its real responsibility (to find out and reflect the views of its citizens) and instead took over the health Board’s responsibility for public health policy.

The council set itself up as a “tribunal” to make judgements on the science – a task they were clearly not equipped for.

The “tribunal” process

Tegan McIntyre, the Hamilton City Council’s Strategy and Research Unit manager, recently revealed a little of the process used by the council in its judgment of the science around fluoridation. She released “a list of the key research papers referenced during the submission and tribunal process.” She also described the “in-house evaluation” of that research. This evaluation appeared to find the research acceptable if it was “validated (peer reviewed) and/or published in an acknowledged peer-reviewed journals.”

You can download Tegan’s list –Scientific research supporting the stopping of fluoridation. The research seems to have been chosen using some sort of popularity index – she says “Please note, this list does not cover all the reports referred as this was extensive but focuses on the ones most frequently cited.”

So, the unrepresentative nature of submissions is a bit of a problem to start with – the summary of submissions says – ”

“Of the 1,557 submissions received 1,385 (89%) seek Council to stop the practise of adding fluoride to the Hamilton water supply. 170 (10.9%) seek Council to continue the practise of adding fluoride and 2 (0.1%) submitters did not indicate a stance.”


This in a city which showed 70% support for fluoridation at its 2006 referendum!

The validity of scientific research determined by this sort of popularity contest. Or by the way the councillors and council bureaucrats kept referring to “experts on both sides” as if it was simply a matter of weighing the submissions without any proper evaluation of the validity of claims made by the “experts.”

This approach is not acceptable for scientists who are used to critical consideration and in depth analysis of published research.

However, maybe it’s a natural way for bureaucrats without the scientific background necessary to make sense of a large number of submissions. I am sure the anti-fluoridation activist organisations realise this and I can understand why they use the approach of swamping such hearings with unrepresentative numbers of submissions, basically repeating the same message.

I will comment below on the documents in the list and the validity of the Council’s assessments. Sorry for the inevitable length of these comments. You can download a pdf to read at your leisure.

1: Public Health Investigation of Epidemiological data on Disease and Mortality in Ireland related to Water Fluoridation and Fluoride Exposure by Declan Waugh.

Declan Waugh is a darling of the anti-fluoridation movement. He also made presentations (written and by Skype from Ireland) to the “tribunal” so I am not surprised to find it top of the list. Apparently the Council evaluated the document highly because it was a “literature review collated by environmental scientist/consultant.”

I haven’t had time to critically consider this specific document but in the scientific world Declan Waugh’s work is not so highly regarded. The Irish Expert Body on Fluorides and Health evaluated Waugh’s previous report – which he considers his “main Report” – (Human Toxicity, Environment Impact and Legal Implications of Water Fluoridation)  and found it was “not reliable.” That while the “report is expertly produced and is impressive in size and appearance. However, in spite of its presentation, its content is decidedly unscientific” (see Appraisal of Waugh report – May 2012). Among specific points it made are these (see Executive Summary of Appraisal of Waugh report – May 2012):

  • “The allegations of ill health effects are based on a misreading of laboratory experiments and human health studies, and also on an unfounded personal theory of the author’s.
  • There is an absence of reporting of the bulk of the scientific literature which points to the lack of harmful effects from fluoridation.
  • The views of authoritative bodies such as the World Health Organisation, the European Commission and others are significantly misrepresented.
  • There is a misunderstanding of the evidence of benefits to oral health and with regards to enamel fluorosis.
  • The view that there is a build up of fluoride in the environment is unfounded and not supported by the evidence.”

Anyone willing to spend a little time can make their own evaluation of Declan Waugh’s scientific integrity simply by checking his approach to citations.

Two examples:

On page 74 of his “main report” we find the claim:

“Fluoride is known to be an inhibitor of enzymatic activity and research has identified fluoride as an inhibitor of homocysteine hydrolase.363

The cited paper is:

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

Waugh is citing work about “fluoride-containing adenosine analogs” to make the claim about the fluoride anion. Extremely sloppy!

On Page 75 he claims:

“Current research has also identified the link between fluoride and atherosclerosis.370

The cited paper is:

Li Y, Berenji G R, Shaba W F, Tafti B, Yevdayev E, Dadparvar S. Association of vascular fluoride uptake with vascular calcification and coronary artery disease. Nucl Med Commun. 2012 Jan;33(1):14-20.

Those familiar with the claims made by anti-fluoridation propagandists will recognise this paper. It concluded “[18F]fluoride PET/CT might be
useful in the evaluation of the atherosclerotic process in
major arteries, including coronary arteries. “ Fluoride does not cause atherosclerosis but because fluoride is associated with calcium containing products of atherosclerosis – fluoride is only along for the ride – the authors proposed the technique for detecting atherosclerosis.

Waugh uses citations like a drunk uses a lamp post – for support rather than illumination. And this causes him to use the citations dishonestly – as evidence for claims that they actually don’t support. Try checking out a few citations yourself.

2:  Ethics of Artificial Water Fluoridation in Australia by Niyi Awofeso

This appears to be an academic discussion of the ethical issues involved and comes out in opposition to fluoridation. Effectively it balances  health equity against individual autonomy – a values/political judgement. The Council evaluated the document highly because it was “Published in a peer-reviewed international journal.”

I could not get the full text of this document so can’t really comment on it – except to conclude from the abstract that no scientific issues seem to be discussed.

3: Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis by Anna L. Choi, Guifan Sun, Ying Zhang,and Philippe Grandjean

If you are familiar with the fluoridation debate you will recognise this paper – it is one of the most quoted by anti-fluoridation commenters on the internet.  The Council evaluated the document highly because it was “Published in a peer-reviewed research and news journal published with support from the National Institute of Environmental Health Sciences.”

The study often seems to be quoted alongside outrageous claims like the Nazis used fluoride in the concentration camps to placate inmates. Or the US government adds fluoride to water to keep the population from revolting (see Fluoridation and conspiracy theories).

Because of the study’s misuse to attack fluoridation the authors warned in a press release:

“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. We therefore recommend further research to clarify what role fluoride exposure levels may play in possible adverse effects on brain development, so that future risk assessments can properly take into regard this possible hazard.”

One problem is that the effects on IQ were seen at high fluoride intakes (studies were of Chinese localities with a range of fluoride in drinking water from both natural and industrial pollution sources). The “control” ‘low fluoride exposure” groups in this study are often exposed to fluoride concentrations comparable to that achieved by community water fluoridation schemes. Andrew Sparrow illustrated this with the following infogram:


Another problem is that no causal link between fluoride and IQ levels was sought or found. The fact that some of the locations suffered from industrial and coal pollution means these IQ effects, if real as social factors were not elimated, could have been caused by any number of pollutants.

This work should not have been considered relevant to the question of fluoridation of Hamilton’s water supply – despite its popularity with anti-fluoridation submitters.

4: Critical review of any new evidence on the hazard profile, health effects, and human exposure to fluoride and the fluoridating agents of drinking water by SCHER

The Council evaluated the document highly because it was “Published by one of the independent non-food Scientific Committees which  provides the European Commission with scientific advice.

This review is often cited by both sides. Reasons for anti-fluoridation citing could include the clear assertion that fluoride “is not an essential element for human growth and devlopment.” But the review does make clear the fluoride is beneficial for oral health. Misunderstandings often revolve around precise usage of words like “essential.”

Another reason could be the vague comparsion between “topical fluoride application” and “systemic” intake of fluoride. This could enable anti-fluoridationists to claim fluoridated water is ineffective. However, the report does refer to the effectiveness of maintianing “a continuous level of fluoride in the oral cavity.” Fluoridated water does do this.

Again this illustrates the need for careful and critical evaluation of the scientific literature and the need to avoid simple claims which may incorrectly cite that literature. I just don’t think politicans and bureaucrats can be relied on for that.

5: Estimated Dietary Fluoride Intake For New Zealanders by Peter Cressey, Dr Sally Gaw and Dr John Love

The Council evaluated the document highly because it “was prepared as part of a Ministry of Health contract for scientific services.”

It is a straightforward desktop study of the “dietary fluoride intakes for a range of age and gender sub-populations based on New Zealand data.” There are no surprises in the data, although the interest for anti-fluoridationists was probably their findings for  formula-fed infants:

“The estimates for a fully formula-fed infant exceeded the UL [upper level of intake] approximately one-third of the time for formula prepared with water at 0.7 mg fluoride/L and greater than 90% of the time for formula prepared with water at 1.0 mg fluoride/L. However, it should be noted that the current fluoride exposure estimates for formula-fed infants are based on scenarios consistent with regulatory guidelines, rather than on actual water fluoride concentrations and observed infant feeding practices.”

They conclude “the very young appear to be the group at greatest risk of exceeding the UL.” However:

“the rarity of moderate dental fluorosis in the Australia or New Zealand populations indicates that current exceedances do not constitute a safety concern, and indicates that the UL may need to be reviewed.”

Anti-fluoridationist have made some mileage out of this, taking advantage of parent’s’ understandable concerns about their children. They (and the Hamilton City Council in their initial advice to ratepayers) advised parent not to use fluoridated water to make up formulae when infants are  fully formula-fed.

While the current expert advice is a little confusing it does take account of the need for review of current UL’s and considers use of fluoridated water safe for fully formula-fed infants. However, they also advise that if parents are concerned they should use non-fluoridated water for part of the feeding – a peace of mind matter.

Again, I question if the “tribunal” really understood the complexity of the situation for fully formula-fed children. Even though health experts had explained the situation during the hearings they apear to have simply accepted the anti-fluoridationist’s interpretation of this research.

Maybe it was the loudest, or more frequently presented, message which prevailed?

6: Fluoride in Drinking Water: A Scientific Review of EPA’s Standards by National Research Council Of  The National Academies Committee on Fluoride in Drinking Water.

The Council evaluated the document highly because the national research council is a “government funded research entity.”

This report usually get cited by both supporters and opponents of fluoridation – however, it actually does not have direct relevance to fluoridation of water supplies at the concentrations used in New Zealand (0.7 – 1.0 ppm) or in the US (0.7 to 1.2 ppm). “The charge to the committee did not include an examination of the benefits and risks that might occur at these lower concentrations of fluoride in drinking water.”

The NRC’s task was to evaluate the scientific evidence to determine if the Environmental Protection Agency’s maximum recommended levels of 4 ppm F should be lowered. They concluded it should be lowered to below 2 ppm to avoid any severe fluorosis. Anti-fluoride activists very often cite this report because of its thorough discussion of the negative effects of fluoride observed at high concentrations. They rarely admit that these effects are not reported for the concentration range used in public water fluoridation. This sort of scare-mongering often comes up in political debate but I would expect a critical evaluation of the report would have recognised that it is not relevant to the Hamilton situation.

But then again, why should we expect politicians and bureaucrats to be capable of such critical consideration.

7: Water Fluoridation: a Review of Recent Research and Actions by Joel M. Kauffman

The Council evaluated the document highly because although the “journal  is not listed as an academic journal but as a professional association journal. [It]Has a double-blind peer-review process.”

This was published in the Journal of American Physicians and Surgeons which really has no scientific standing. Issuepedia says “the journal does not appear to be considered respectable by the scientific establishment because:

  • It is not listed in the major literature databases ( MEDLINE/PubMed nor the Web of Science).
  • The World Health Organization found that a 2003 article on vaccination published in the journal had “a number of limitations which undermine the conclusions drawn by the authors.” 
  • Quackwatch lists it as an untrustworthy, non-recommended periodical. 

Investigative journalist Brian Deer described the journal as the:

“house magazine of a right-wing American fringe group, the Arizona-based Association of American Physicians and Surgeons, which campaigns against US vaccination policies. The association is also vocal in opposing moves to combat fraud by private doctors, and medical professional efforts to reduce deaths from domestic firearms. In 2005, Time Magazine reported that the association had only 4,000 members. Although cited by Private Eye in stories attacking MMR, the association’s journal – recently renamed from the Medical Sentinel, presumably for the purpose of attempting to give its ideologically slanted material the aura of science – is barely credible as an independent forum for such material. No objective medical scientist with important information of any standard would submit it to such a publication, unless they couldn’t get it published anywhere else.”

So much for the Hamilton City Council high evaluation. But the paper itself is not at all convincing. It’s claims are poorly supported. It relies heavily on citation of sources from anti-fluoridation activists. Much of the citation is to just one book Fluoride: Drinking Ourselves to Death by Barry Groves – a staple anti-fluoridationist manual. Kauffman’s ideological motivation are obvious.

8: Prevention and reversal of dental caries: Role of low level fluoride  by J. D. Featherstone.

The Council evaluated the document highly because it was in a “ranking academic journal.”

This paper is often cited by anti-fluoridationists as support for their claim that the “topical mechanism” of protection of existing teeth means that fluoridated water is ineffective. Yet the paper clearly includes “fluoride in drinking water” (as well as in “fluoride-containing products”) as operating via the topical mechanisms. Featherstone has also stressed drinking water in recent descriptions of the “topical mechanism” (Topical Effects of Fluoride in the Reversal and Prevention of Dental Decay). I can only conclude that some people have the wrong impression through superficial reading and their conclusions have been adopted by others without any checking. The Fluoridation Action network NZ (FANNZ) website even claims, incorrectly, that a topical effect of fluoridated water on teethis contradicted by Featherstone.”

Again, and again, I find this website very misleading in their use of citations.

The Hamilton City Council repeated this incorrect interpretation of topical mechanisms in their information leaflet for citizens (see Topical confusion persists) – a serious mistake which has been strongly criticised by health professionals. Did Council bureaucrats simple take the anti-fluoridationist use of this citation at their word – without any checking?

9: Why I changed my mind about water fluoridation by J. Colquhoun.

The Council evaluated the document highly because it was in a “Peer-reviewed academic journal published by Johns Hopkins. Author: former dental officer in New Zealand during the 1970s and early 1980s”

This is really a memoir, and not a high quality review. I found that it generally gave a lot of emphasis to longitudinal studies which show improvement in oral health over time for both fluoridated and unfluoridated areas. This may have suprised researchers at the time but is well recognised today and, by itself, is not evidence against the effectiveness of fluoridation. He also seems to be very selective, some would say cherry-picking, in referring to studies where comparison have been made between fluoridated and unfluoridated areas. The all appear to show either no effect, or that oral health was better in the non-fluoridated areas! (Anti-fluoridations regularly do such cherry-picking today).

Colquoun presented the “topical” mechanism as an argument that fluoridated water is ineffective – a suprising interpretation for someone familiar with the literature. However, I guess his committment to the anti-fluoridationist cause when he wrote this memoir might explain the faulty interpretation.

10: The mystery of declining tooth decay by Mark Diesendorf

The Council evaluated the document highly because it was published in “Nature [which] is a prominent interdisciplinary scientific journal. Ranked the world’s most cited. “

Although Diesendorf is an environmental scientist he is also an anti-fluoridation activist. In this paper he relies heavily on longitudinal studies, where oral health was found to improve in both fluoridated and unfluoridated areas over time. This is a well accepted observation, explained by improvements in diet and care of teeth, as well as availability of fluoridated toothpaste. I believe some of this improvement is also due to changes in dental practice involving less fillings.

Such research does not invalidate the also well recorded difference in oral health between fluoridated and unfluoridated areas observed in many good studies. However, the longitude observations still get trotted out as evidence against fluoridation by the anti-fluoridation activists.

Despite the high standing of Nature, this paper does come across as somewhat one-sided, maybe partly because of its age (1986).


The mistaken approach of the Hamilton City Council in its “tribunal” judgement of the science behind fluoridation illustrates the problems of the current situation where councils effectively make decisions about fluoridation because they manage water supplies. This can force them into a role for which they have neither the skills nor the training – making scientific and health judgements. Anti-fluoridation activists have taken advantage of this anomaly with a certain amount of success.

The Medical Association has called the debate on fluoridation to be raised to a national level. “Medical Association chairman Dr Mark Peterson says it’s not ideal for it to be discussed at a regional level and not nationwide.” This could be a way of avoiding the problems illustrated by the actions of some councils – including the Hamilton City Council.

The way scientific research was evaluated by the Hamilton City Council and its bureaucrats shows what can happen when such evaluations are not done critically by people with expertise in research and some understanding of the issues involved. Discussion and decision of the fluoridation issues at the natioanl level could help ensure such evaluations are done by bodies better equipped for the job.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
Fluoridate our water Facebook page
New Zealanders for fluoridation Facebook page

Activists peddle chemical misinformation for fluoridation referenda

The propaganda produced by anti-fluoridation activists reminds me of this cartoon.


There are just so many examples of this in a flyer produced by the Fluoride Action Network of NZ (FANNZ) for the upcoming fluoridation referenda in Hamilton, Whakatane and Hastings. Here is just one small section describing the fluoridating chemicals used in New Zealand.


They are, of course, referring to the most commonly used fluoridating, chemicals –  fluorosilicic acid and sodium fluorosilicate. I have written about these chemicals, and the FANNZ misinformation on them before – see Fluoridation – are we dumping toxic metals into our water supplies?,  Water treatment chemicals – why pick on fluoride?  and Hamilton – the water is the problem, not the fluoride! .

The claims on the flyer are just misleading, if not outright lies. Just in the extract above (only a small part of the flyer):

1: Fluorosilicic acid is a by-product of the fertiliser industry in New Zealand. There is a market for that chemical (if only a relatively small one in New Zealand because we don’t have a fluoride industry) so it is not waste.  Sure, in its concentrated form it is corrosive and toxic – as are all such chemicals. Including those used in water treatment like chlorine, sodium hydroxide, aluminium sulphate, etc. (see Water treatment chemicals – why pick on fluoride? ).

2: No, it is not food grade, neither is the chlorine, sodium hydroxide and alum used in water treatment. Because they aren’t used in foods – especially at those concnetrations.

3: Contamination with “mercury, arsenic, lead, cadmium and other heavy metals” is extremely small (see Fluoridation – are we dumping toxic metals into our water supplies?,  Water treatment chemicals – why pick on fluoride?  and Hamilton – the water is the problem, not the fluoride! ). Regulations define permissible levels of contaminants in our water supply and the chemicals used to treat it. They are based on known health risks of such chemicals and include large safety factors.  Suppliers must fulfill these requirements, and provide certificates of analysis from independent laboratories, or the material is rejected.

Here is an example of the data from a Certificate of Analysis for a batch of fluorosilicic acid supplied to the Hamilton City council earlier this year:


Those levels of heavy metals are extremely low. FANNZ has access to this information – a copy of this certificate was supplied to the local FANNZ representative by the Hamilton City Council. So why do they persist with this lie about contamination with toxic heavy metals?

4: No, it is not the same as naturally occurring calcium fluoride (CaF2). But when diluted in water fluorosilicic acid and the fluorosilicate anion decomposes to form the fluoride anion (F) and silica.


The reaction is driven to completion by removal of SiO2 from solution. The fluoride anion is exactly the same as that in calcium fluoride and a solution of dissolved CaF2. It is the F species which provides the beneficial action to teeth and bones.

5: No it has never been tested for human safety at the low concentrations used in water fluoridation – for a very good reason. You can’t prepare a solution of fluorosilicic acid at these low concentrations because of its decomposition (see equation above). But, because it is hydrolysed to form F, safety studies carried out with fluoride solutions prepared from chemicals like sodium fluoride and CaF2 are completely relevant. Remember, the fluoride anion is the fluoride anion, whatever its origin.

Chemical confabulation

Anti-fluoridation activists are nothing if not faithful to their story. They perform all sorts of difficult mental gymnastics when confronted with the facts above. Some of them will invent anything to deny these facts. For example:

Claim 1: The fluorosilicate does not decompose completely – it still gets into your drinking water and body. They will even quote Crosby et al (1969) who reported “that sodium fluorosilicate, at the concentration normally present in public water supplies, is dissociated to at least 95%.” The activists choose to interpret “at least 95%” to mean they have 5% to point to, and not representing any margin of error in the data.

There have been a number of studies specifically for checking the completion of hydrolysis of fluorosilicate anion at low concentrations. Although equilibrium measurements indicate complete hydrolysis it was necessary to make sure that kinetic factors did not inhibit the reaction.

Most of these studies were reviewed by Urbansky 2002, in his paper “Fate of Fluorosilicate Drinking Water Additives.” He concluded that all the chemical “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.”

Similarly, Finney et al (2006) investigated fluorosilicate hydrolysis using 19F NMR and reported their results agreed with “previous findings that at pH ~ 7 and at typical drinking water formal fluoride concentration, hexafluorosilicate dissociation to produce free fluoride ions will be essentially complete.”

Claim 2: Fluoride in natural CaF2 is bound tightly to Ca and the extra Ca acts as “a partial antidote to fluoride toxicity, so, obviously, the statement ‘fluoride is fluoride is fluoride’ is misleading.”

As a chemist I find this confused but several anti-fluoridation activists have made that claim to me. Fluoride exists in solution as the hydrated F anion – not directly connected to a cation as in the solid crystal. Effectively it is independent of the cations in solution. Sure, if there is excessive Ca2+ then CaF2 crystals will precipitate. And other ions could also promote removal of other insoluble products. But in solution fluoride is fluoride is fluoride. It is not influenced by its origin.

Really, this sort of gobbledygook is just an attempt to avoid reality. It is not science.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
New Zealanders for fluoridation Facebook page

Hamilton – the water is the problem, not the fluoride!

Saw this on Facebook the other night – together with the comment:

“If Hamilton don’t want fluoride in the water, how about we replace the water”


Yes, that would be convenient, wouldn’t it. Instead of Hot and Cold taps, why not Red and White?

However, there is an element of truth in the joke. To some extent, the Waikato water is the problem, rather than fluoride added during fluoridation. Anti-fluoridationists are concentrating on the “evils” of the fluoridation agent, fluorosilicic acid, without realising that the source for our water supply in Hamilton introduces more contamination than the fluoridation chemicals.

Have a look at this graphic showing the levels of arsenic (As) in the Waikato River. Through almost the entire length of the river As levels are several times higher than the recommended maximum concentration for human consumption which is 0.01 parts per million (ppm).

The source water for the Hamilton water treatment plant is 2 or 3 times that recommended maximum As concentration.

Fortunately the treatment process remove about 80% of the As.

Let’s compare that with the contamination introduced by fluoridation chemicals.

A typical concentration of As in fluorosilicic acid is 2 ppm (see Fluoridation – are we dumping toxic metals into our water supplies?  and Water treatment chemicals – why pick on fluoride?). There is a large amount of dilution of the fluorosilicic acid when added to water at the recommended dose (0.7 – 1.0 ppm). The final concentration in our drinking water is 0.0001 ppm As. Several orders of magnitude lower than the maximum recommended concentration for human consumption.

In reality, even after removal of 80% of As from the source water the major contribution to any As contamination in Hamilton’s public water supply is the Waikato River itself – not the fluoridation chemicals. By several orders of magnitude.

  Original Arsenic (ppm As) Dilution Contribution to finished water (ppm)
Recommended maximum As (ppm)     0.01
Waikato River water ~0.025 None ~0.005
Fluorosilicic acid 2* ~200,000 ~0.0001

* see Fluoridation – are we dumping toxic metals into our water supplies?  and Water treatment chemicals – why pick on fluoride?

Haven’t the Hamilton anti-fluoridation campaigners got their priorities wrong when they complain about contamination of the fluoridation chemicals used?

See also:

Making sense of fluoride Facebook page
Other Fluoridation articles

Topical confusion persists

I got a little leaflet from the Hamilton City Council the other day – with my rate demand. The leaflet tells me the council has stopped adding fluoride to the city’s water supply, gives some advice on alternative sources of fluoride – and then assures me their decision was all for the best. Because:

“Application by toothpaste and other means that directly affect the tooth surface are much more effective at reduing tooth decay than fluoridation of water supplies.”

Trouble is that is just wrong. I shows the council did not learn anything about the mechanism of fluoride protection against tooth decay from their recent hearings . Worse, they are confused – and are passing on their confusion to their citizens.

I discussed this issue of the topical mechanism in my article Fluoridation – topical confusion. But I guess it bears repeating because the Hamilton City Council is not the only group confused about this. And the anti-fluoridation activists are working hard to spread that confusion.

It’s a topical mechanism –  not application

When the word “topical” gets mentioned in this situation we need to understand clearly this refers to the mechanism of inhibiting mineralisation – not to the method of application. The topical mechanism is the major one preventing decay of existing teeth at all ages, it operates at the tooth surface ( and just below) and relies on having a relatively continuous low concentration of F in the saliva and biofilms on the teeth.

Fluoridated water (and fluoride in our food) participates in that mechanism of protection. Some of the fluoride in the drink and food gets transferred directly to saliva, and thence the tooth surface – during consumption.

Anti-fluoridation activists attempt to confuse the issue by talking about fluoride which is ingested, metabolised and then excreted from the salivary duct at a concentration lower than in fluoridated water. That fluoride has little effect at the tooth surface – because of its low concentration.

It is the fluoride transferred directly to saliva during the act of drinking (or consumption of food) that provides a sufficiently high concentration to have a protective effect. That is, F is transferred to the saliva, and then biofilms, during drinking and eating – something we do regularly. The concentration  in saliva spikes and then declines over an hour or so.

The US Center for Disease Control stresses this mechanism in its  report Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States:

” . . 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.”

The diagram below portrays this – the fluoride is going directly from the drink and food into the saliva:


Mineralisation and remineralisation = tooth decay

Tooth decay occurs because when the pH at the tooth surface is lowered (this happens bacteria decompose sugars) some of the the calcium hydroxy apatite at the tooth  surface dissolves – mineralisation. With time the pH increases and the reaction is reversed – calcium and phosphate ions at the tooth surface reform as the solid hydroxy apatite (remineralisation).

When fluoride is present at the tooth surface a fluorohydroxy apatite is formed. This is “harder” – it doesn’t dissolve as readily. Consequently the incorporation of fluoride into the tooth surface reduces mineralisation – and enhances remineralisation. It inhibits tooth decay.

It turns out that F in fluoridated water and food does this very effectively. And, because we drink and eat often, dietary forms of fluoride help to maintain a useful concentration of saliva fluoride over time.

Topical application methods (toothpastes and dentrifices) are a supplement to fluoridated water and dietary fluoride, but not a substitute – partly because they are not applied as often (if at all). Even here it seems their mode of operation may be by the formation of CaF2 globules on the tooth surface (because if the high F concentration) which then slowly release their F over time to maintain saliva concentrations at an appropriate level (see the  review article Mechanisms of Action of Fluoride for Caries Control by Buzalaf, Pessan, Honório, and ten Cate JM (2011)).

This topical mechanism which operates with fluoridated water means that the whole population can and does access the “topical mechanism” without thinking about it. Unfortunately the anti-fluoride lobby are spreading a lot of misinformation about the word “topical.” And, now, so is our local City Council.

The dangers of consultation

Hamilton City Councillors came in for a lot of criticism after their shock decision to end fluoridation. In their defence they claim their consultation process (“The Fluoride Tribunal”) gave them then information they needed – and the process was “robust.” (That word “robust” is the latest trendy word at the council these days).

But the fact they are repeating this mistaken description of the topical mode of fluoride protection against tooth decay shows it was far from “robust.” Despite all their efforts – and the large number of submissions, the council got it wrong.

I have watched many of the videos of submissions I know that the group of experts from the Waikato District Health Board and Ministry of Health did explain this topical mechanism. I know they explained it clearly. So why did the “tribunal” get it so wrong?

Here’s a couple of reasons which come to mind:

  1. The expert submissions were swamped by the submissions from anti-fluoridation activists (about 90% of the submissions). Many of those repeated the misleading interpretation of the topical mode of action.
  2. The Council had set itself up as a “tribunal” (my dictionary describes that as a group “with the authority to judge, adjudicate on, or determine claims or disputes.”) They were assuming they had the power, knowledge and ability to make an authoritative judgement of the scientific evidence set before them.
  3. The council appeared to give at least equal credence to “both sides” – councillors often referred to hearing evidence from “eminent experts on both sides.” Apparently an academic title was enough to show credibility in the eyes of these councillors – no attention being paid to the submitters background, specialisation or research experience.
  4. Worse, some of the councillors appeared to give more credence to the anti-fluoridation submitters than the District Health Board and Ministry of Health experts. A telling comment from one councillor was his reference to attempting to balance information from “experts who do no research and non-experts who do all the research.” His concept of research seemed to be internet Google searching and listing multiple but unsubstantiated claims. I experienced hostility from several councillors who were very dismissive of any reference to science.

It seems to me the sort of consultation set up by the Hamilton City Council was poorly thought out. It should never have been seen as a “tribunal” set up to make judgments about the science of fluoridation or possible health problems. The council members just do not have the scientific ability – or indeed the necessary skills in critical thinking, to make judgements in such a complex area. They could not produce a decision reflecting the best judgment of the evidence – and indeed they didn’t. Their document purely listed common arguments presented by submitters. There was no assessment of credibility, evidential support or confirmation.

If an assessment of the current science around fluoridation was really required then this should have been done by appropriate professionals – not politicians. The council should have relied on such an expert review, or in its absence, the recommendation of the proper experts. Instead they set themselves up in judgment of the complex science – and took evidence from some of the most inappropriate sources.

In the end, a referendum at the next local boy elections was the only way to resolve the pickle they had got themselves in to. Hopefully the new council will not make the same sort of mistakes about fluoridation advice.

See also:

Making sense of fluoride Facebook page
Other Fluoridation articles

Fluoridation – an organised campaign to misinform.


Credit: World Congress for freedom of scientific research

In my article Poisoning the well with a caricature of science I mentioned the anti-fluoridation activists in the US using a conscious strategy of casting doubt on the science. It strikes me this is also a conscious strategy used by local activists on this subject.

They are dong this by making unjustified claims about the nature of the fluoridation chemicals, the possible toxic effects of fluoride and the efficacy of fluoridation in limiting tooth decay. In the series of articles I have written on this blog there are a number of clear examples where scientific findings have been distorted or completely misrepresent in the anti-fluoridation propaganda. See, for example: Is fluoride an essential dietary mineral?
Fluoridation – are we dumping toxic metals into our water supplies?Fluoridation – topical confusionFluoridation and conspiracy theories.

Internet, newspapers and local bodies

The outright distortions are being disseminated by a very active and organised letter writing campaign on the internet, to newspapers and to local bodies. Because of the responsibility of local bodies for water supply these activist organisations see them as a key target in their misinformation campaign. Soften them up with letters, get a hearing of submissions which they dominate (quantitatively but not qualitatively) and then get a decision to stop fluoridation. Hamilton was just such an example.

A short note on a recent posting at the Fluoride Action Networks Facebook page gives an idea of how this misinformation can work. This is a reply the network got from the Manawatu District Council:

“Thank you for your submission on the fluoridation of the Council’s water supply. Council is interested in your arguments and believe they warrant closer examination. Council also believes that the Ministry of Health’s pro-fluoride position should be reviewed. However, Council does not believe it has the expertise to evaluate the evidence itself.”

I think this is quote revealing for several reasons:

  1. The council recognises they do not have the expertise to check the evidence they are getting from the anti-fluoridation network (or anywhere else, presumably). Seems sensible – call in the experts.
  2. Despite this lack of expertise they have concluded that the Ministry of Health’s “pro-fluoride” position should be reviewed. (I can only imagine this was because of peroieved public pressure as they lack any expertise).
  3. There is an implication that perhaps the Ministry of Health’s expert advice should be discounted because they are “pro-fluoride.” Hence a false balance between the expert’s scientific advice and the activist’s misinformed and distorted “science.”

We saw all these factors in the Hamilton example.

The council and the Mayor admitted they did not have the expertise to judge the evidence. They even passed a resolution asking for these sorts of decisions to be made by central government.

Despite this acknowledgement they went ahead and set themselves up as a tribunal to review and make decisions on the science! Several councillors justified the decision by repeating  some of the pseudoscience they had been dished up as if it were fact. They now consider themselves experts on the subject!

Some councillors also discounted correspondents who took issue with their interpretations, and the very bodies with the expertise – the Ministry of Health and the District Health Board. Some councillors have gone as far as suggesting that limitations should somehow be placed on the ability of these bodies to communicate with Hamiltonians during the buildup to the October fluoridation referendum!

I don’t necessarily blame members of councils for getting into this position. After all, they are given the responsibility to make the decision. And their concepts of community consultation can easily be distorted when activists groups with international backing come in from outside with a highly organised campaign to misinform them

But really the Hamilton experience should make other New Zealand councils suspicious of these campaigns. After all, this council did come out against the views of its citizens demonstrated in the 2006 referendum and in more recent polling. Consequently they came in for a certain amount of ridicule from local media and commenters for their anti-fluoridation decision.

The fight back

I hope councils will also take on board the warning of the Minister of Health about this issue. Tony Ryall warned councils and communities that:

“There will be people who come from out of town and tell all sorts of shock-horror stories around fluoridation.

“Communities need to know that that’s part of the strategy that these groups run, and they should look to their local district health boards, their local dentists and the evidence which shows that fluoridation in NZ is safe and does benefit families.”

This week’s NZ Listener editorial (The fluoride debate) described the anti-fluoridation campaign as “clever and bellicose” and warned “the anti-fluoridation lobby saw the win [in Hamilton] as a stepping stone to the likes of Auckland and Wellington.”

According to this editorial the Minister of Health has ordered officials to marshal the strong scientific case for both the health benefits and safety of fluoridation in strengthening and protecting teeth against decay.” He sees an increased responsibility for the Ministry of Health, and probably district health boards, to counter the anti-fluoridation misinformation campaign.

Personally I think this is an important response – but it still suffers from being seen as a battle between institutions and grass-roots activists. There is a limit to the amount of initiative such institutions can take.  We need more scientific and health experts to also be seen, by name, opposing and exposing this misinformation.

See also:

debunking anti-fluoridation arguments

Similar articles

Hamilton gets its fluoridation referendum

referendum2It was a close thing, (passed by 7 votes to 6) but today the Hamilton City Council decided to hold a referendum on fluoridation of its public water supply at the October elections (see Hamilton to go to referendum on fluoride).

This represents a backdown from their decision last month to stop fluoridation – – despite a previous referendum and all their polling showing citizens support for the treatment.

In my mind this local experience raised a number of questions.

1: The questionable validity of the hearings process held by the Hamilton City Council. This was swamped by anti-fluoridation activists with only a few speakers (mainly institutional) supporting fluoridation. (There are no activist pro-science groups, unfortunately). This appeared to sway councillors who were exposed to a lot of “sciency” sounding misinformation, often extensively but falsely referenced. Councillors also appeared to be taken in by quantity and not quality, and seeing it as an issue on which scientists didn’t agree. They were fooled into the false “balance” argument – placing the activists “experts” on the same, or often higher, level of credibility as the experts in the District Health Board and Ministry of Health,

2: Council just don’t have the skills for this job. In effect, councillors were put in a position of having to make scientific judgements for which they are just not trained. The Mayor more or less admitted this when she said councils should not be put in this position and the decisions should be made by central government.

While such hearings have often been preferred to referenda I think this example shows how easily they can be captured. At least a referendum represents the will of the people, even if that can be influenced by chemophobia and activist propaganda. At least most people do put value on expert opinion.

3: The foolishness of council ignoring public opinion. I find incredible that the council could have made that June decision  knowing that their polling showed it would not be popular. Did they really think they had raised themselves to expert status and therefore could over-ride that public opinion as well as expert advice?

4: The anti-science sympathies within the council. I communicated with all the councillors asking them to support a referendum and was shocked at the response of a minority (3). This was rude (extreme in one case), accused me of being involved in some sort of internal political infighting, and discounted any reply I made to their claims on the science of fluoridaiton. In effect these 3 councillors seemed to think that the “science” stories they got from the activists groups was of higher value than any comment made by a scientist. Not just me but also other people expressing concern and those on the District Health Board and Ministry of Health teams.

For example a warning about misinformation in the activists’ submissions brought accusations of being “condescending, and even a bit offensive” and scientists comments were described as “designed to put down those involved, and are unscientific themselves.” No explanation of  what they based the claim on given. Yet the anti-fluoridationsts have been making quite irresponsible claims about the science and scientists, as well as our health institutions, without a single complaint.

And let’s face it, concerns expressed in the letters to the councillors really only echoed those of the Minister of Health.

But I have learned something

This experience brought home to me that anti-science attitudes are relatively widespread, even extending into representative bodies like councils. This is a bit of a shock as Hamilton has a long history of scientific research institutes and the University of Waikato in or near the city. In recent years science based industries and innovation centres have also proliferated. I had thought this scientific presence had actually promoted good attitudes towards science in the local community.

I must say, I was also surprised at such a rude response from a few councillors just months before the local body elections. I would have thought they would not be silly enough to offend voters in such a silly way.

Oh well, the Council has given us a referendum and I also found the experience useful in another way. I now have some good information which will help me in my voting decisions next October.

See also:

debunking anti-fluoridation arguments
Fluoridation – topical confusion
Fluoridation and conspiracy theories
Fluoridation – the violation of rights argument.
Poisoning the well with a caricature of science

Getting a grip on the science behind claims about fluoridation
Is fluoride an essential dietary mineral?
Fluoridation – are we dumping toxic metals into our water supplies?
Tactics and common arguments of the anti-fluoridationists

Poisoning the well with a caricature of science

Spoiler alert – if you haven’t seen this video before have a look at it before reading on.

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