Controversial IQ study hammered in The Lancet

I have discussed the paper by Grandjean & Landrigan (2014) before in the article Repeating bad science on fluoride. So have other bloggers and commenters. On the other hand anti-fluoride propagandists are still promoting it heavily in social media and “natural” health web sites.

But the cogs of science publishing have ground slowly on and the scientific critiques are starting to appear. The last issue of The Lancet (which published the original paper) has several articles in the correspondence section critical of the paper (see Neurodevelopmental toxicity: still more questions than answers). Two of these related to claims made about fluoride.

Unsubstantiated claims, misquoted studies

Virginia Feldman wrote that the authors:

“make unsubstantiated claims and misquote previous studies to pull together heterogeneous elements and drugs into a group of substances termed neurotoxicants.

The investigators’ claim of new data is undermined by 24 of the cited references being their own previous, mostly review articles . . . . . . Their “strong evidence” for adding fluoride was a finding from Grandjean’s own review of older Chinese studies. Contrary to their statement—“Confounding from other substances seemed unlikely in most of these studies”—findings from many previous meta-analyses have shown the faults of using intelligence quotient (IQ) data from countries with highly polluted air and water; non-validated IQ tests; poor controls for parent IQ, socioeconomics, and other variables; and studying mega-doses in animals and in human beings. By contrast with this review of Chinese studies, all of problematic methodological robustness, more than 3000 studies of the safety of water fluoridation stretch over 65 years. During this time, as fluoridation increased from 0% to 72% of US households, average US IQs have not decreased, but have instead increased by 15 points.”

She also directs the authors’ attention to a paper by one of their frequent co-authors, David Bellinger, about determining IQ points lost (Grandjean & Landrigan 2014 claimed fluoride can cause a 7 point drop in IQ). Bellinger specifically says the meta-analyses of the sort used by Grandjean & Landrigan (2014) are just not suitable for calculating IQ points lost.

Unacknowledged research

Julianna Gelinas and Myron Allukian were also concerned about the authors’ reliance on very flimsy evidence. The “claim that fluoride might cause neurodevelopmental harm” is “based on only one paper, of which Grandjean is a coauthor.” Further describing the limitations of that study they say “it contains several flaws that undermine its credibility and calls into question its applicability to the community water fluoridation programme in the USA.”

“The study is a meta-analysis of 27 cross-sectional studies done in poor, rural communities in China, Mongolia, and Iran, countries where the drinking water contains high levels of naturally occurring fluoride. The 27 original studies did not adequately control for a variety of intervening and confounding variables that could have affected intelligence quotient (IQ) scores, such as parents’ education and socioeconomic status and air and water pollution. It is unfortunate that Grandjean and Landrigan did not mention these limitations.

Additionally, they did not clearly state that the reference groups in their article use water fluoridated at about the recommended level. Thus, another interpretation of their analysis could be that communities fluoridated at the recommended level have a higher IQ.”

Nor did Grandjean and Landrigan acknowledge research showing fluoride was not harmful:

“No credible scientific studies show a relation between fluoride consumption and IQ levels; however, several have shown that fluoride ingested at recommended levels is not harmful. Grandjean and Landrigan did not acknowledge the animal study that showed no evidence of a neurotoxic effect of fluoride, even at levels up to 230 times the recommended concentration; an earlier study showing that fluoride causes no harm to children; two formal reviews that delineate weaknesses in the Chinese fluoride and IQ studies; and the conclusion by one of these sets of investigators that biological plausibility for a link between fluoridated water and IQ has not been established.”

Request for statement on fluoridation

They are also concerned at the way the original paper is being used by anti-fluoride propagandists:

Unfortunately, Grandjean and Landrigan’s Review has been aggressively and improperly used by antifluoridationists to frighten the public about the effects of fluoridation, a well-established public health measure that has been shown to be cost-effective and safe. As a result, the public’s oral health, especially that of the most vulnerable people, is put in jeopardy. . . .

A statement from Grandjean and Landrigan clearly stating that their addition of fluoride to their list of neurotoxins does not apply to fluoridation at the recommended levels of 0·7—1·2 ppm would clarify our concerns on the misuse and misinterpretation of their paper.”

The authors’ response to these criticisms was brief and rather flippant.  They claim other reviewers of their meta-analysis were “without access to important background information” – without providing information on this. They dismissed Feldman’s reference to the increase in population mean IQ as a “serious error” – again without justification or explanation.

The remained silent about the way they had relied on very few sources, often their own, in their review.

So some important criticisms of the original paper and ones that the authors did not respond to properly. But will this stop anti-fluoride propagandists relying on this paper – one that very few of them have bothered reading?

I doubt it.

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New group challenging the anti-science brigade

Here’s a recent press release from a new group, The Society for Science Based Healthcare, which is having some successes in challenging anti-scientific advertising.


Controversial Church Caught Red Handed

The Advertising Standards Authority (ASA) upheld three complaints from the newly formed Society for Science Based Healthcare today regarding misleading health claims.

The Universal Church of the Kingdom of God, DailyDo and Pure Wellbeing have all been asked by the ASA to remove adverts that make misleading health claims.

The Universal Church of the Kingdom of God, which was recently embroiled in controversy regarding claims that its holy oil could heal a variety of serious health problems, has had a second complaint upheld against it. Bishop Victor Silva, when responding to a previous successful ASA complaint, had promised that:

“When we come to hold another similar event, we will take external advice as to the content of any promotional material to doubly ensure that it is fully compliant with all regulation and that there is no chance of another complaint of this nature.”

Despite these assurances, within 3 weeks of this promise the church sent out another advertisement for a “chain of prayer” series of events. This advert claimed that “IT WORKS!” and that a “HEALING” session covered cases such as “When doctors & medicines are not enough” and “incurable diseases”. A majority of the complaints board agreed that “the Advertiser had presented their religious beliefs in evangelical healing as an absolute fact, rather than opinion, and may mislead and deceive vulnerable people who may be suffering from any of the illnesses listed in the advertisement”. The board ruled to uphold the complaint.

DailyDo, a daily deals website, advertised amber teething necklaces with phrases such as “Traditional homeopathic treatment for teething babies, designed to help provide relief”. As the advertiser was unable to provide any evidence to support their claims, the ASA ruled that “the advertisement was misleading and had not been prepared with the high standard of social responsibility required for products with intended therapeutic use”.

This is the latest in a long series of successful complaints regarding misleading health claims about amber beads, which resulted in a new ANZA guideline being written. In response to the complaint, the ASA has sent a copy of this guideline to other “one day deal” sites.

A number of advertisers of these products, such as Baa Baa Beads, have had complaints upheld against them but have refused to remove their misleading claims. Now that the Fair Trading Act has been recently updated to prohibit unsubstantiated claims in trade, the Society for Science Based Healthcare hopes that the Commerce Commission will step in to put a stop to claims such as these. The Society intends to file a complaint with the Commerce Commission against companies that continue to make these misleading claims.

The Pure Wellbeing website advertised Detox Foot Patches, claiming that they could remove “toxins” and heavy metals “By stimulating the reflexology points and the blood circulation”. Because the advertiser failed to provide any evidence that the claims they were making were true, the complaints board ruled that the advertisement was misleading and must therefore be removed, upholding the complaint made against it.

There were also two settled complaints from the Society for Science Based Healthcare, against a homeopathy advert by Ngaio Health and a colour therapy advert by Colour Therapy Manukau. Both companies had claimed that they were able to treat serious health conditions such as cancer, but did not substantiate these claims. In both cases the company agreed to remove the claims.

The Society for Science Based Healthcare welcomes these decisions, and hopes that the advertisers involved will take them to heart and refrain from making misleading health claims in the future. These are the latest in a long line of complaints about misinformation regarding healthcare, and as there is still plenty of misinformation out there you can expect to hear more from the Society in the future.

About the Society for Science Based Healthcare

The Society for Science Based Healthcare is a newly formed consumer advocacy group that aims to protect consumers’ rights to make informed healthcare decisions. Although the society itself is new, over the past 2 years its founders have lodged over 50 successful complaints with the ASA regarding misleading health claims, dealing with products and services ranging from chiropractic and acupuncture to magnetic mattress underlays and a quantum magnetic health analyser.

Mission statement

“We believe that a strong basis in rigorous science is a necessary prerequisite for providing safe and effective healthcare. Decisions regarding public funding of healthcare in New Zealand should therefore be science based. We support public health measures that have a clear basis in science and evidence, and oppose those that do not.
We will work to counter misinformation about health issues propagated by individuals and organisations in New Zealand.
Consumers have the right to make an informed decision about their healthcare, and should not have to worry about being misled by unsubstantiated claims.”

Relevant links

Society for Science Based Healthcare –
Advertising Standards Authority –
Universal Church of the Kingdom of God –
DailyDo –
Pure Wellbeing –

Upheld Complaints:

Settled Complaints:

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Fluoridation: what about reports it is ineffective?


Fluoride dental treaments also reduce tooth decay

Anti-fluoridation activists are always making claims that fluoridation is not effective. Even sometimes claiming that children in non-fluoridated areas have less tooth decay than those in fluoridated areas. And they will sometimes cite, or link to, scientific papers they believe support these claims.

It’s always worth checking out such claims. Check the paper, find out what it does actually report and what other factors are involved. We should approach the scientific literature intelligently and critically – not cherry pick to support our confirmation bias.

Here is an example of a paper promoted by Declan Waugh purporting to claim that dental health is a result of “social class” and not influenced by fluoridation. The paper is Colquhoun, J. (1985). Influence of social class and fluoridation on child dental health. Community Dentistry and Oral Epidemiology, 13(1), 37–41.

Of course, the role of social economic status in oral health is well known so I am not questioning that. But can that paper actually be used to prove the claim that fluoridation is ineffective or that fluoride does not play a role in oral health?

Colquhoun found no statistical difference in the caries-free percentage of children in fluoridated and non-fluoridated areas around Auckland when areas of “similar social rank” were compared. And of course anti-fluoridation activists like Declan Waugh pounce on that finding – which is supported by the data. But what other factors are involved.

If Declan had read the paper – or was at all interested in conveying the important facts – he would have seen this important note by Colquhoun:

“It should be noted, when comparing child dental health in different areas in this way, that in New Zealand all school dental clinic patients in unfluoridated areas receive routine 6-monthly topical fluoride applications, while only selected “at risk” children receive them in the fluoridated areas. Also, vigorous educational and preventive work, including encouragement of use of fluoride toothpastes, has been carried out in both kinds of areas.”

This even made it to the abstract:

“In the unfluoridated areas all the children, and in the fluoridated areas only selected children, had received regular topical fluoride treatments. In both areas the use of fluoride toothpastes and oral hygiene had been encouraged.”

This information is vital to the conclusion. Colquhoun had allowed for the “socioeconomic variable” but had not allowed for the different dental treatments of the two groups of children. The fact that all children of non-fluoridated areas were receiving 6-monthly topical fluoride applications and most children from fluoridated areas were not is an important factor.

Maybe Colquhoun’s paper can be used to argue that other fluoride treatments may be as effective as community water fluoridation – but his data certainly does not support the claim that fluoridation is ineffective. I guess there was a bit of confirmation bias on Colquhoun’s part – but certainly cherry-picking and confirmation bias on Waugh’s part.

Community water fluoridation is only one of the ways to improve oral health using fluoride. Regular brushing with fluoridated toothpaste, fluoridated salt or milk, and regular fluoride dental treatments also work. These other sources and treatments should always be considered when evaluating this sort of data.

Maupomé, et al (2001) made this point in their conclusions from a study on patterns of dental caries after cessation of water fluoridation. They wrote:

“Our results suggest a complicated pattern of disease following cessation of fluoridation. Multiple sources of fluoride besides water fluoridation have made it more difficult to detect changes in the epidemiological profile of a population with generally low caries experience, and living in an affluent setting with widely accessible dental services. There are, however, subtle differences in caries and caries treatment experience between children living in fluoridated and fluoridation-ended areas.”

An intelligent and critical approach to the scientific literature means we should always keep this in mind when reading papers like this.

And we should never take the claims made by activists like Declan Waugh at face value.

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Approaching scientific literature sensibly


We all suffer more or less from confirmation bias – it is just human.  So it’s natural for people to be selective, and to indulge in some cherry-picking and biased interpretation, when quoting scientific literature to support an idea they promote.


In the scientific community peer review and continual submission of ideas to scrutiny by colleagues helps keep this under control. But it can really get out of hand when used political activists use the literature to support their claims.

I have got used to anti-fluoride commenters on social media simply citing a paper or even providing a bare link, without comment, as if this somehow makes their claims irrefutable. Perhaps, in truth, they have not even read the paper they cite, or understood it, so do not feel confident discussing it.

But this tactic is particularly lazy – and stupid. To simply give a Google Scholar search as proof. Lately I have been presented with links to such searches to argue that fluoridation is toxic. Just a search for “fluoride toxicity.”

This is what that search produces – 234,000 hits:

Fluoride toxicity – 234,000 results


Sounds good to the uninitiated, I guess. It does seem to produce a large number. But does that mean anything?

What about searching for water toxicity. This produces over 2 million hits. Are we to assume from this that water is toxic, seemingly 10 times more toxic than fluoride?

Water toxicity – 2,190,000 results


Yes, I know some social media do not offer much space for commenting but that should not be an excuse for such silly citations.

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Declan Waugh’s misinformation on fluorosilicic acid

Declan Waugh argued recently that silica species produced when fluorosilicates are hydrolysed in water cause a whole range of health problems and deaths. A new theory for him - silica is the problem, not fluoride! He is wrong, of course (see An open letter to Declan Waugh – new mechanism for fluoride toxicity?).

Declan had previously argued the exact opposite. That fluorosilicates do not hydrolyse completely in water and it is the remaining fluorosilicate species that are toxic and cause all these effects. He summarised his arguments and evidence for this in his 2012 report Hexafluorosilicic Acid, Raw Materials, Manufacture, Toxicity and Public Health Concerns as an Active Ingredient in Drinking Water.

This report is typical of Waugh’s writings. He distorts or misrepresents the literature and makes unwarranted inferences. He is not the only person doing this – it’s a common feature of the confirmation bias and cherry picking endemic to the anti-fluoridation movement. However, for some reason some people consider he is an authority on the subject (perhaps they have been fooled by his own hubristic claims to be an “environmental scientist and fluoride researcher”) so his reports get used as evidence and are something quote. For example, the Hamilton City Council listed one of his reports first in the “scientific evidence” which convinced them to stop fluoridation last year (see When politicians and bureaucrats decide the science ). Mark Atkin, the science and legal spokesperson for the local anti-fluoridation group is also fond of citing Declan Waugh – maybe because Waugh is the only source he can find to support his own confirmation bias.

Waugh Hamilton

A poster prepared by Declan Waugh to advertise the decisive effect of his submission to the Hamilton City Council fluoride tribunal

In this article I consider some of the claims Waugh makes in the above report and show how he uses distortions and misrepresentation of the literature he cites to support them.

Exaggerating toxicity of fluoride

This part of Waugh’s report is confused but he quotes the relative toxicities of CaF2 and H2SiF6 (1 to 25) to apparently argue “that 1 ppm of hexafluorosilicic ingested orally is the equivalent of 25 ppm calcium fluoride.”  He then seems to argue that the regulated  concentration limits for fluoride are really for CaF2 – implying that since we use fluorosilicic acid for water fluoridation we should introduce a factor of 25. He seems to say that the limits should not be 1.5 ppm F (he says is set for CaF2) but 1.5/25 = 0.06 ppm! He says:

“The drinking water standards were established for the much less toxic calcium fluoride which is listed as a moderately toxic compound compared to hexafluorosilicic acid, which is categorised as extremely toxic.”

All this ignores that the toxic species in CaF2 is the fluoride anion. This is the same for fluorosilicic acid in drinking water as the fluoride anion is the end product of its hydrolysis when added to water. In fact the relevant species is the fluoride anion whatever the source – NaF, CaF2 or fluorosilicic acid. So the relative toxicities Waugh quotes for solid CaF2 and concentrated fluorosilicic acid are irrelevant.

Calcium fluoride is relatively insoluble (about 15 ppm CaCl2 = 7.3 ppm F) so when the solid is ingested there is less dissolved fluoride anion available to exert a toxic effect. That is why it is less toxic than the readily soluble NaF and fluorosilicic acid. But CaF2 is soluble enough to easily maintain the optimum concentration of fluoride anion required for the beneficial effect (0.7 ppm F). One could use it to fluoridate water – although the mechanics would be difficult as very little dissolves. Whatever the source, NaF, CaF2 or fluorosilicic acid, the end product in drinking water is the same so introduction of such relative toxicities is misleading.

Claim hydrolysis is incomplete

Waugh says:

“When added to drinking water Hexafluorosilicic acid dissociates into free fluoride ions, it is now accepted that this reaction is not complete with the possibility of some silicofluoride compounds remaining present in drinking water.5
It is further known that the following fluorosilicate species may be present in treated water. However current analytical methodologies are not yet available to accurately measure or quantify the level of residual fluorosilicates or fluorosilicon complexes that may be present.”


Strange. He is claiming that we currently do not have the analytical methods to measure or quantify residual fluorosilicates but nevertheless “it is now accepted” and “further known” silica fluoride compounds are present in drinking water. Trouble is neither the table he presents, or the paper he refers to (from which the table is taken) say this. They say the exact opposite!

The table simply lists the different silicofluorides species that have been chemically proposed, reported or inferred in solids, gases or solutions. While some of these may logically exist in water (eg SiF62- and Si(OH)4) there is certainly no evidence that they all do. His reference 5 (Urbansky, E. T. (2002). Fate of fluorosilicate drinking water additives. Chem. Rev., 102, 2837–2854) concludes:

“that in drinking water supply with a pH of 5 or higher, fluoridated with sodium silicofluoride [hexafluorosilicate] to the extent of 16 ppm or less, all of the silicofluoride is completley hydrolysed to slicic acid, fluoride ion and hydrogen fluoride. There can be no question of toxicity of SiF4 or SiF62- under these conditions.”

As for rate of hydrolysis Urbansky (2002) clearly says “all the rate data suggest that equilibrium should have been achieved by the time the water reaches the consumer’s tap if not by the time it leaves the waterworks plant.” This “equilibrium” is essentially the complete hydrolysis of the fluorosilicate as Urbansky and Schock (2000) make clear:

“Based on the above information on both the thermodynamics of the hydrolysis reaction and it’s kinetics, we can safely conclude that there is essentially no (<< 1 part in a trillion) hexafluorosilicate remaining in drinking water at equilibrium and that equilibrium is rapidly reached from the combine uncaltalyzed and metal-catalysed reactions.”

Claim reaction of silica with fluoride in stomach and bladder

Waugh claims:

“According to Urbansky, a senior US EPA chemist and expert upon water fluoridation chemicals” such compounds [H2SiF6, NaF, Na2SiF6 and AlF3] may exist in artificially fluoridated drinking water as well as in low acidic environments within the human body (i.e. Stomach and bladder) after consumption of fluoridated water.3


“It is also now hypothesized that incomplete dissociated SiF residues may re-associate both at intra-gastric pH and in the bladder which are low ph environments9 (thereby exposing the consumer to toxic harm) and during food preparation (low pH soft drinks) producing SiF species including silicon tetrafluoride, (SiF4), a known toxin. It is also believed that commercial SiFs are likely to be contaminated with fluosiloxanes.”

His reference 3 is to Urbansky (2002) and 9 is to Ciavatta, L., Iulianno, M., & Porto, R. (1988). Fluorosilicate Equilibria in Acid Solutions. Polyhedron, 7(18), 1773–7779.

The falseness of his claim that Urbansky provided evidence of the existence of fluorosilicates in drinking water was discussed above. Urbansky and Schock (2000) actually put the theoretical proportion of silica present as fluorosilicate in the “most acidic gastric conditions” at less 0.0002%. As for Ciavatta et al (1988) – their work has no relevance to the stomach or bladder. They studied the reaction of silicic acid and fluoride in 3 Molar Lithium perchlorate with an acidity between 0.3 and 3 Molar. An ideal solution for the laboratory investigate of chemical equilibria but more extreme than conditions in our stomach and bladder.

So again, Waugh has misrepresented the literature and distorted its relevance to the situation in drinking water and our body.

Nevertheless, Waugh get cited as evidence for incomplete fluorosilicate hydrolysis and for recombination in the stomach. For example Mark Atkin relied on this report of Waugh’s in defending this erroneous claim before the NZ Advertising Standards Authority (see Anti-fluoridation advertising deceptive).

Finney et al (2006) is also often used by anti-fluoridationists to claim recombination in the stomach because they showed presence of an intermediate SiF species at pH values below 3.5 (SiF5-). Again this is a laboratory study with higher F concentrations and no interfering species. In the real world drinking water (and especially the stomach content) has all sorts of chemical species, many of which react with F, Si(OH)4 or both. These will displace any theoretically derived equilibria. I have not seen any reports of detection of silicofluorides species in the stomach or bladder. Nor have I seen anything to suggest that these would be any more toxic than fluoride itself – or any of the other chemical species present in the stomach.


Readers having read my comments here and those on Waugh’s theory about silica toxicity (An open letter to Declan Waugh – new mechanism for fluoride toxicity?) might see a pattern:

  • Citation of scientific literature to given credibility to Waugh’s claims;
  • Misrepresentation of the cited literature – often claiming they report the exact opposite of what they in fact do;
  • Confirmation and cherry picking which is very clear to any intelligent reader;
  • Attempt to establish himself as a “scientific authority” on fluoridation which can be used by anti-fluoridation activists to support their own claims.

I guess you can fool some of the people some of the time. But it does show that  such material should always be approached critically and intelligently.

PS: I would of course welcome Declan Waugh’s response to this article. After all, I might be completely wrong – but I won’t know that without some sort of exchange with him.

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A healthy attitude towards quantum mechanics

Credit: xkcd.

Apparently the above quote “You can safely ignore any sentence that includes the phrase’ according to quantum mechanics” is used by Robert P. Crease and Alfred Scharf  in their upcoming book The Quantum Moment: How Planck, Bohr, Einstein, and Heisenberg Taught Us to Love Uncertainty.

Good advice.

An open letter to Declan Waugh – new mechanism for fluoride toxicity?

Dear Declan,

You describe yourself as a scientist and fluoride researcher so I feel the responsibility to bring to your attention what I think are major flaws in a recent presentation of yours. I am sure you understand that research and the scientific ethos requires and encourages constructive criticism, and in fact the debate over ideas and hypotheses is an essential part of the scientific process. I offer my criticisms with this in mind and therefore assume you will receive them in the same open spirit  and give them your honest consideration.


In this presentation to the  Nutritional Therapists of Ireland, Health Impacts of Water Fluoridation May 2014 you make several arguments which I think violate basic chemical principles. You then go on to claim a mechanism for many health complaints you claim results from community water fluoridation.This is a novel mechanism because it attributes health problems not to fluoride but to silica resulting from the hydrolysis of fluorosilicates used as fluoridation chemicals.

Below I list the steps in your argument together with my comments on these:

Slide 16:


You claim “ultra fine silica particles”  form on hydrolysis of fluorosilicates. You cite Finney et al (2006) for this. However, nowhere in  Finney et al (2006) is there a reference  to”ultra fine silica particles.”

What they describe is the well-known hydrolysis reaction:

SiF62-(aq) + 4H2O(l) ↔ 4H+ + 6F- + Si(OH)4(aq)

The silica species produce is the monomeric molecule Si(OH)4. This soluble (“reactive”) silica exists in solution but has a very complex chemistry. Polymerisation occurs and a number of molecular species are possible in solution. The end product of such polymerisation can be solid silica but, on the other hand, solid silica can support a concentration of monomeric silica in solution.

Yes, molecules in solution are extremely small but it is plain  wrong to describe them as if they were just very small, or “ultra fine,” particles of the solid.

Slide 17:


You now go further describing these molecules as “nanoparticles” and cite Napierska et al (2010) to tell viewers that nanoparticles can have negative health effects. They can be toxic. This is a huge leap, on top of the huge leap in the previous slide.

You have gone from a monomolecular species (Si(OH)4), to a finely divided solid,  to “nanoparticles.”

No way is it legitimate to describe a small molecule like Si(OH)4 as a “nanoparticle.” One definition of a nanoparticle describes is as a “microscopic particle with at least one dimension less than 100 nm.” Simple molecules like Si(OH)4 are thousands of times smaller.

Slide 18:


You now put these ideas together to imply that fluoridation can cause a large range of health problems via formation of nanoparticles during hydrolysis of the fluoridation chemical and their toxic reaction in the bloodstream. I believe your arguments here are false, you have not given any evidence to support them, and in fact you have misrepresented the citations you used.

Silica in drinking water

Your wild “theory” introduces a big can of worms which you should have considered but actually ignore. Silica, reactive or monomolecuar silica, exists in all drinking water, fluoridated and unfluoridated. Here are some examples from New Zealand community water supplies. Please note, fluoridation  is irrelevant. In fact the highest levels of reactive silica occur in an unfluoridated supply.

Fluoride (mg/L) Reactive silica (mg/L)
Hamilton Templeview Site 23.08.13 0.16 37
Hamilton Site 12.02.14 0.19 34
Christchurch Christchurch <0.1 16
Wellington Waterloo 0.78 15.5
Wainuiomata 0.83 12.55
Auckland Auckland 0.81 13.23

None of this is surprising as silica will be derived from all sorts of natural, geological, sources the water contacts.

Did you bother comparing natural levels of reactive silica with what could be expected from the hydrolysis of fluorosilicates? My estimates suggest that fluoridation with fluorosilicate at the optimum level (0.7 mg F/L) would produce a reactive silica concentration of 0.37 mg SiO2/L. Surely you can agree this is miniscule compared with he natural levels of reactive silica in all drinking waters?

Your hypothesis of a toxic role of monomolecular silica in drinking water implies  all drinking water is unhealthy and that, in fact, fluoridation could contribute only an insignificant amount to this toxicity.

A serious charge which most scientists would consider better justification and evidence than you have given so far. Personally I think it would be irresponsible of you not to publicly withdraw these unwarranted claims.

I think there are similar faults in the way you have used statistical health information to imply a link of fluoridation to a whole host of health problems but that is a separate issue. At this stage I look forward to a response to my specific chemical criticisms listed above.

If you wish to defend your hypothesis, or to debate this specific issue and the wider claims you are making, I would be happy to offer you space on the Open Parachute blog for an exchange of articles. This proved a very effective method of scientific discussion in my exchange with Paul Connett (see Fluoride Debate). Many anti-fluoridation activists seem to hold you in the same regard as Paul and rely on your for much of their information. You have also contributed submissions to local body councils in New Zealand considering the fluoridation issue. I am sure you would therefore welcome the opportunity to present your scientific claims to a scientifically literate audience that this exchange can offer.

I look forward to your response.

Kind regards

Ken Perrott.


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Toxicity is in the dose or concentration of fluoride

FKANI came across a new organisation, the Fluoride Knowledge & Action Network, the other day. I first thought this is another one of those fluoride free activist groups and it is probably part of Paul Connett’s Worldwide Alliance to End Fluoridation. Digging a little deeper I was pleased to see it did not belong to this alliance, which is really just the anti-fluoride equivalent of the Comintern or the Fourth international.

In fact the Fluoride Knowledge & Action Network is an Indian organisation and describes itself as “a network of passionate people interested in finding solutions and improving awareness for the Fluorosis problem in Rural communities by working on safer water & better nutrition.”

So it’s not another one of these political activist anti-fluoride groups we have become so used to here. It is actually concerned with a real problem caused by excessive fluoride in water and diets which can cause severe dental fluorosis and skeletal fluorosis. These are real problems in parts of India, China,  Africa and the Middle East. They are not a problem in New Zealand and are not caused by fluoride at the optimum concentrations used in water fluoridation.

So, I wish the Fluoride Knowledge and Action Network well in their future activity. They are dealing with an important problem in their area and hopefully won’t get diverted by Connett’s organisation. I think that is a possibility because the fluoride free groups, and the “scientific” journal Fluoride they love to quote, does try to make capital out of these real problems by arguing that they are also a problem with fluoridation in countries like New Zealand. They aren’t.

Most of us understand the concept of “too much of a good thing.” This is also true with diet and with essential and beneficial micro-nutrients and micro-elements.  So it is not surprising to realise that, like selenium, fluoride can also be toxic at high concentrations but beneficial at lower concentrations.

Misrepresenting toxicity of fluoride

Trouble is, political activists opposing fluoridation often resort to using high dose, or high concentration, situations to argue against fluoridation. Here are a few example I came across today while browsing social media.

Remember – the optimum concentration for fluoridation of community water supplies is 0.7 ppm F.

Here’s a couple  of papers promoted by Carol Kopf, the Media Director of Paul Connett’s Fluoride Action Network. She uses the Twitter account @nyscof – the New York Coalition Opposed to Fluoridation, Inc.

  1. Zhou, Y., Qiu, Y., He, J., Chen, X., Ding, Y., Wang, Y., & Liu, X. (2013). The toxicity mechanism of sodium fluoride on fertility in female rats. Food and Chemical Toxicology : An International Journal Published for the British Industrial Biological Research Association, 62, 566–72.

    These workers reported harmful effects of sodium fluoride on rats supplied with drinking water containing 100 and 200 ppm F.

  2. Simon, M. J. K., Beil, F. T., Rüther, W., Busse, B., Koehne, T., Steiner, M., … Oheim, R. (2014). High fluoride and low calcium levels in drinking water is associated with low bone mass, reduced bone quality and fragility fractures in sheep. Osteoporosis International : A Journal Established as Result of Cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 25(7), 1891–903.

    The paper reported negative effects on sheep in the Kalahari Desert, Namibia, which were drinking water containing about 10 ppm F.

Fluoride Free Hamilton often quotes “natural” or alternative health sources. Here they link to the article Fluorides: The neurotoxins in water and toothpaste. Trouble is they raise the bogey of high fluoride concentrations (in India) and link it to  flawed work claiming fluoride is a neurotoxin:

“Here in India at least 20 states, including Andhra Pradesh, Kerala, Mahatrashtra and Punjab are victims of elevated fluoride levels.”Fluorides are known to cause brain toxicity and neurological symptoms in humans,” said Philippe Grandjean, adjunct professor of environmental health at HSPH”

See Repeating bad science on fluoride for my comments on Grandjean’s paper.

Fluoride Free NZ is just as bad (well they are the same organisation and people). Fluoride Free Hamilton via Declan Waugh was recently fear-mongering about fluoride claiming it could be causing depression. They posed the question:

Have you noticed how many people who kill themselves are on anti-depressants? Prozac for one, has fluoride compounds in it. I wonder if there is any connection?

And cited to this paper:

O’Hara, P. J., Fraser, A. J., & James, M. P. (1982). Superphosphate poisoning of sheep: the role of fluoride. New Zealand Veterinary Journal, 30(12), 199–201. doi:10.1080/00480169.1982.34940

Simply reading the abstract shows this paper is not relevant to fluoridation. It says, in part, “A lethal dose of NaF caused severe depression, salivation, hyperpnoea, blindness, ataxia and incoordination. Death ensued three to 52 hours after dosing.” This paper described research into superphosphate poisoning of animals forced to graze freshly topdressed short pastures.

I have a picture of a poor sheep which has been poisoned and is lethargically sitting around waiting to die. But evidence for human depression! Come off it.

There is a lesson here of course. Be very wary of anti-fluoridation activists citing scientific papers as evidence for fluoridation being toxic. In most cases they will be using the evidence obtained from studies using much higher concentrations than used in community water fluoridation.

Concentration does make a difference – don’t be fooled.

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Councils and scientists targeted by anti-fluoride activists

Are ducks somehow connected to the anti-fluoridation  movement? Sure – they do have unsinkable rubber ducks in common. But I am thinking of how media coverage of anti-fluoridation activity and the opening of the duck shooting season peaks annually about May.

The seasonal airing of the fluoridation issue is directly connected to council timetables. Councils consider and decide on their draft annual plans about that time. And of course anti-fluoridation activists take advantage of this to make large numbers of submissions and to dominate council hearings on the plans. That’s not to say these activists are inactive the rest of the year. There are submissions to prepare, supporters to mobilise and the never-ending promotion of their unsinkable rubber ducks – misinformation about fluoride.

Anti-fluoride activists have become council “groupies.” They are familiar with council planning and conscious of any opportunity to present their case. Aware that numbers can impress councillors they help supporters with submission templates (templates A, B, C, D, were used in Hamilton) and submission guides. In contrast the ordinary citizen is rarely conscious of what is going on in their council. For example, the first most Hamiltonians heard of the “Fluoride Tribunal” organised by the Hamilton City Council last year was a news report of the council vote to stop fluoridation!


A group of anti-fluoride council groupies after harassing the Wellington Regional Council this year. Credit: Fluoride Free Wellington

To continue reading this article see GUEST BLOG: Ken Perrott – Anti-fluoride activists target councils – and scientists at The Daily Blog.

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Lugansk – a modern Guernica?


With some of the images of death and destruction coming out of the conflict in eastern Ukraine Picasso’s work “Guernica” is starting to take on more meaning for me.