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Hyping it up over fluoridation

In my time as a scientific researcher, honest scientists used to condemn colleagues who over-hyped their science. To our mind there should have been a special place in hell for scientists who misrepresented their findings or dishonestly described their significance.

That sort of self-promotional behaviour is probably understandable for reasons of ambition – or even the attempt to secure future funding. And these self-promoting scientists usually moved on rather quicker into higher-paid administrative jobs. Not exactly to that special place in hell – but maybe their promotion away from active research reduced the damage their personal self-hyping could do to science in the long run (although I did often wonder about the damage they did to science with their administrative decisions).

A recent article (Hype isn’t just annoying, it’s harmful to science and innovation) got me thinking of this problem again – and to realise we are facing a classic case of this self-promotional over-hyping in recent science related to community water fluoridation (CWF).

Readers may pick up that I am referring to the behaviours of a north-American research group which has been indulging in a wave of self-promotion – a promotion which involves misrepresenting of their own findings and the significance of those findings. I have discussed the research findings of this group in a number of posts – including the following:

More recently they have produced a video promoting and misrepresenting the significance of their work. A video which is being gleefully used by anti-fluoride activists in their propaganda (there has been a bit of a dance over this video which has been roundly criticised scientifically and taken down or moved several times so links often don’t work. But a recent appearance was on the New Zealand anti-fluoride Facebook page).

Group members have also attacked, in a very unprofessional way, fellow scientists who have critiqued their work (see for example When scientists get political: Lead fluoride-IQ researcher launches emotional attack on her scientific critics). On social media, they have attempted to close down any critical discussion of their work – and in a similar manner, they purposely ignore, or even attempt to hide, studies that do not support their claims. (At the personal level I have had a member of this group refuse to fulfil their prior undertaking to do a peer review on a draft paper of mine – presumably because on reading it she became aware that my paper discussed flaws in their work).

In support of my contention that this group is over-hyping their findings, and unprofessionally using this misrepresentation to give support to anti-fluoride activists, I will briefly list below what their findings were.

No effect of CWF on child IQ

While claiming their findings support the claim that CWF is harmful to the brains of children they actually refused to even discuss their own reported data which shows this is not the case. In fact, the data in their two main papers (Green et al 2019 & Till et al 2020) show no effect of CWF on the IQ of children. This confirms the finding of Broadbent et al (2015) – the only other study comparing IQs of children from fluoridated and unfluoridated areas (see Canadian studies confirm findings of Broadbent et al (2015) – fluoridation has no effect on child IQ).

The table below lists their data together with that of Broadbent et al (2015)

A comparison of IQ for children and adults living in fluoridated and unfluoridated areas in countries where CWF is used

I think it unprofessional for this group to ignore their own data while at the same time lending support to activists who are claiming that CWF harms child’s brains. Perhaps they assume that this finding could not be hyped to promote their standing and ambitions. So, instead, they have diverted attention to another part of their work – the relationship between child IQ and measures of fluoride consumption.

Occasional weak relationships of child IQ with fluoride intake

While ignoring some other data – which is unprofessional in itself – they have devoted their promotional material to just one part of their findings – the few cases when they are able to demonstrate a relationship, albeit only a weak relationship, of child IQ with fluoride intake as measured by drinking water fluoride content, estimated fluoride intake or urinary fluoride levels.

I have discussed problems with this approach in my articles listed above but will stress here that the relationships are usually not statistically significant, or very weak when significant (explaining only a few per cent of the variance in IQ), and suffer from inadequate consideration of possible important confounders or other risk-modifying factors. A common problem with the sort of “fishing expedition” involving statistical searching of existing databases in an attempt to confirm a bias.

The figure below shows the relationships considered in the two studies. Most simply are not statistically significant. In a recent article (see Perrott, K. W. (2020). Health effects of fluoridation on IQ are unproven. New Zealand Medical Journal, 133(1522), 177–179) I describe it this way:

“Multiple measures for both cognitive factors and of fluoride exposure are used producing many relationships. Only four of the ten relationships reported by Green et al were statistically significant (p<0.5). Similarly, only three of the twelve relationships reported by Till et al were statistically significant. There is a danger that reported relationships could be misleading – as the proverb says, “If you torture your data long enough, they will tell you whatever you want to hear.” “

Relationships of cognitive measures with exposure to fluoride obtained by linear regression analyses using Canadian MIREC database. Red data points statistically significant (p<0.05) and green data points not significant. Bars represent 95% confidence intervals.

Even if the reported relationships correctly reflected reality (being a “fishing expedition” the chances are they don’t) their concentration on such weak relationships (explaining only a few per cent of the data) could be actively diverting attention away from the factors which are more important. Although this group has been very shy about making their data available for other researchers to check, the data they have published indicate that regional and ethnic differences may be making a much bigger contribution to child IQ.

A big problem (always glossed over by those promoting this work) is that the studies are exploratory, using existing data bases rather than experiments specifically designed to answer the relevant questions. Reported relationships may support preconceived beliefs but it is easy to ignore important confounders or risk-modifying factors (which properly designed experiments would attempt to minimize).

I highlighted the problem of inadequate consideration of other factors in my article critiquing an early paper from this group (see Perrott, K. W. (2018). Fluoridation and attention deficit hyperactivity disorder a critique of Malin and Till (2015). British Dental Journal, 223(11), 819–822). In this case, I showed that when regional factors (in thas case elevation) were included in the statistical analysis the relationship of ADHD prevalence with the extent of fluoridation that Malin & Till (2015) reported simply disappeared.

It is worth adding that in subsequent reports from this group my critique has been completely ignored and they still reported the flawed Malin & Till (20915) as being reliable. I think that is very unprofessional but it does align with the tactics of self promotion and over-hyping of their work.

The down-side of self-promotional hype in science

The article I introduced at the beginning (Hype isn’t just annoying, it’s harmful to science and innovation) finished by concluding:

“Acting this way has a cost. It’s not just about allowing people to feel awe: it’s about empowering those who are not professional scientists or technologists to be able to participate, instead of being spoon-fed a whizz-bang watered-down version of science as cheap entertainment. Hype doesn’t just obscure the reality of what’s going on in science and technology – it makes it less interesting. It’s time we start to look past it and delight in what lies beyond.”

So as honest working researchers we were right to resent self-promotional hype and, perhaps, to wish that a place in hell was reserved for these ambitious self-promoters.

But, looking back, I can recognize that scientists are human and, like everyone else, fallible. It is easy to see how people will place ambition over the truth and why that should resort to hyping their science for ambitious reasons. I can also recognise, as Ioannidis (2015) reported, that “Most Published Research Findings Are False.” I believe Ioannis is basically correct and there are big problems with the scientific literature which contains reports from so many studies based on an exploratory statistical analysis of the sort indulged in by this North American group.

It’s inevitable that such poor science will be seized on by those with political, commercial and ideological agendas to support their claims. This has been done by the anti-fluoride activist groups. For the rest of us it is matter of reading the scientific literature intelligently and critically. And I mean all the literature, not just that related to fluoridation, vaccination and similar “hot topics.”

And, in the end, the truth will out. Poor science and self-promoting ambition and hype do get exposed. The faults in the promotional messages do get exposed. And, new research and data usually provide context for a proper evaluation of the claims made by those which currently hype their work.

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June ’20 – NZ blogs sitemeter ranking delayed

Unfortunately, due to a medical emergency, I have landed in hospital so am not able to do a current update on the NZ blog statistics.

Let’s hope I can get back to this in good time.

September ’18 NZ blog ranking – delayed

Gaztelugatxe on Gulf of Biscay coast, Spain

An apology

I am on holiday so will be a few weeks late with this month’s blog rankings.

Opportunities and problems for grassroots activism offered by the internet

Caitlin Johnstone is an amazing woman. Very literate and on the ball politically.

Her analysis of recent changes in information transfer offered by the internet and the reaction of mainstream media is important. This speech, “How to Win a Grassroots Media Rebellion,” is well worth watching.

It explains a lot of the recent history of the media, the control of information and the threats to media and internet access by ordinary people.

If you find her arguments interesting follow her on Facebook, Twitter, the Medium, and on Steemit.

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Visualising the numbers – The Fallen of World War II

Today and tomorrow we remember the end of the war in Europe 72 years ago. I think this video provides a fitting illustration of what that war meant to nations and families around the world – and why we commemorate its end.

It’s also an excellent example of what can be done with data visualisation. I don’t think I have seen a better presentation of the reality of that war – of the numbers of soldiers and civilians killed in the different countries during that war.

Something to aspire to for anyone involved in data presentation.

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Fluoridation: Making sense of the Ministry of Health data

Image credit: Built in Colorado

Every year local anti-fluoride activists eagerly await release of the latest Ministry of Health (MoH) data on the oral health of New Zealand School children. These data are a mine of examples which can be cherry-picked to argue that community water fluoridation is ineffective – or even that the oral health of children in non-fluoridated areas is better than fluoridated areas.

Well, the latest data (for 2015) has just been released and the anti-fluoridationist reaction is typical. They are presenting selected data to argue that “the gap [between the numbers of caries-free children in fluoridated and non-fluoridated areas] has become practically non-existent.”

And the make a big thing of comparing this “practically non-existent” gap with the 40% difference claim they attribute to the MoH. Needless to say, they are wrong.

Let’s have a look at what the 2105 data shows, how this compares with data from previous years and what the limitations of the data, and consequently any conclusions drawn from the data, are.

The data

The figures below show the data – I have included it in graphs showing the data for earlier years. Notice that the data is for Māori and “Other.” This is because the “Total” figures in the data tables throw all ethnic groups together and are therefore misleading. As I have pointed out several times in the past (Anti-fluoridation cherry-pickers at it again A challenge to anti-fluoridationers to justify their misrepresentation of New Zealand researchDebunking anti-fluoridationist’s remaining 12 reasons for opposing fluoridation and Schluter & Lee 2016 noted in their paper Water fluoridation and ethnic inequities in dental caries profiles of New Zealand children aged 5 and 12–13 years: analysis of national cross-sectional registry databases for the decade 2004–2013), Pacific island children, whose oral health is poorer than other groups, are concentrated in fluoridated areas of Auckland. This distorts the “Total” figures (in particular underestimating the oral health for fluoridated areas). Local anti-fluoride propagandists have taken advantage of this in the past to make untruthful claims.

The “Other” group will be mainly Pakeha, but also will contain some Asian. I have not included the data for Pacific island children – the relatively small number in non-fluoridated areas mean the comparison is rather erratic.

Data are presented for “% caries-free” – the proportion of children with no tooth decay, and mean dmft – the average number of decayed missing or filled tooth for each child.

5-year-old children

In summary, the reduction of dental decay (using % caries-free figures) for 5-year-old Māori varied between 8% and 60% in the years 2005 – 2015 and was 25% in 2015.

In summary, the reduction of dental decay (using % caries-free figures) for 5-year-old “Other” varied between 3% and 22% in the years 2005 – 2015 and was 3% in 2015.

Year 8 children

In summary, the reduction of dental decay (using % caries-free figures) for year 8 Māori varied between 12% and 48% in the years 2005 – 2015 and was 12% in 2015.

In summary, the reduction of dental decay (using % caries-free figures) for year 8 “Other” varied between 5% and 27% in the years 2005 – 2015 and was 5% in 2015.

Average effects

It’s worth looking at average effects out over several years to limit the effect of variability in the data. The is the result of the effect of fluoridation in reducing tooth decay (using % caries-free figures) – average effect in the period 2005 – 2015.

Average reduction of tooth decay: 2005 – 2015

  5-year-olds Year 8 children
Māori 33% 27%
“Other” 11% 15%

Problems with the data

Of course, this data is not meant to provide definitive measurements – it is simply the records for oral health (% caries-free and dmft) for different regions. There has been no determined effort to make sure that the resident regions of the child are the same as the school region. While there is some separation into ethnic groups there has been no effort to take into account factors like sex differences, socio-economic influences, dietary differences, and other dental treatment differences. For example, in some regions the health authorities have a programme of treating children in non-fluoridated areas with fluoride varnishes or taking extra steps to provide access to dentists.

It’s interesting that the anti-fluoride people prefer such data to more definitive data corrected for problems. Well, they do at the moment as they are cherry picking to support their claims (see MoH says Fluoridation reduces dental decay by 40% – No it doesn’t!). They are very critical of data from the MoH’s New Zealand Oral health Survey. The MoH acknowledged limitations inherent in this survey for determining an effect of fluoridation – and the anti-fluoride people love to quote that acknowledgment. But at least the Survey did give data:

“for people living in non-fluoridated areas, which are adjusted for age, sex, ethnic group and neighbourhood deprivation to allow appropriate comparisons with people living in fluoridated areas.”

Instead, the anti-fluoride people rely on cherry-picked comparisons from data where no such adjustments have been made. And they never acknowledge the limitations of that data.

Fluoride Free NZ cherry-picks data without correcting for ethnic differences, etc., to make their claim.

The “Halo Effect”

The graphs above do show a tendency for the fluoridated and non-fluoridated lines to approach each other. One could speculate on the reasons and more definitive studies are required to check out such speculation. But here are some of my ideas:

The results could be influenced by changes in residential vs school or dental clinic location. For example, the introduction of “hub and spoke” dental clinics during the 2000s may mean that more children now live in a region with different access to fluoridated water than that for the clinic or school. The recent provision of extra dental care, such as fluoride varnishes or more dentist visits in non-fluoridated areas, is also a likely possibility.

But another possibility is that the efficacy of community water fluoridation is declining – maybe because of better health care, diet, and parental responsibility. In fact, the evidence indicates that community water fluoridation may now have less importance in some cases than dietary intake from other food sources. This graph from a US Environmental Protection Agency report (Fluoride: Exposure and Relative Source Contribution Analysis) shows fluoridated water may now contribute less than 50% of the dietary intake for many children and certainly no more than 70%.

Percentage Media Contribution to Total Daily Fluoride Intake. Figure 7-1 in EPA report Fluoride: Exposure and Relative Source Contribution Analysis.

This has resulted in a “Halo effect.” Because processed foods and beverages now contain more fluoride than in the past (when non-fluoridated water may have been used in processing) the difference in total dietary fluoride intake between children living in fluoridated and non-fluoridated areas has been reduced. The common use of fluoridated toothpaste also contributes to this “Halo Effect.”

This does raise the question – if community water fluoridation is less important as a dietary source perhaps it could be stopped? Although the warning is that if community water fluoridation was stopped perhaps other dietary sources like processed foods and beverages would have a lower fluoride content and dietary intake would then fall below optimum levels.

It’s a complex issue.


Once again the local anti-fluoride activists have been caught out misrepresenting the MoH data by cherry-picking and purposely ignoring important factors like ethnicity.

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‫Tha Amnesty report – and a response from Syria

Amnesty International has just produced a report on mass executions in a Syrian prison. It has received a lot of publicity and can be downloaded from Human slaughterhouse: Mass hangings and extermination at Saydnaya prison, Syria.

The trouble with reports like this is that they can be based on limited evidence – yet once published they become evidence themselves. From now on people will cite this report as “evidence” for mass atrocities in Syria, despite the fact the report contains only a small amount of evidence, mostly hearsay from opposition sources, and extrapolates freely to produce very large numbers.

I agree – where there is smoke these is usually a fire. And I do not believe Syria has been exempt from human rights problems. But, then again, what country – inducing those claiming to be bastions of democracy – are really exempt from human rights abuses? And do the human rights violations in secular Syria occur so frequently or unjustly as in neighbouring Gulf states like the theocratic Saudi Arabia?

Anyway, download and read the report if you are interested. I have. But I have also looked for critiques of the report.

I think the above interview with the Syrian President provides some response to the Amnesty report. His specific comments on the report occur from about 13 minutes on – but the whole interview is very interesting. Because of his views on the Syrian conflict and its possible solutions. But also in his refusal to interfere in the internal affairs of the US by taking sides in domestic disputes.

Perhaps we could all learn something from his attitude.

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Trump’s victory – why the surprise, why the anger?

This morning my social media threads seem full of emotional outbursts, even hatred, and the ripping of garments. All over the results of the US presidential elections.

But I have to ask – why this emotion? Why the surprise? And why blame the voters.

Why the surprise? Surely a Trump victory was on the cards – even a strong possibility? At least that is how it appeared to me. But then again I did not have a dog in this race. I wasn’t going to vote. I didn’t support either of the main candidates – and weren’t we all saying it was a matter of choosing between two evils? Then why get so partisan, so emotional?

Perhaps it is because of that irrational indulgence – wishful thinking. By the media – to me the election coverage of the main stream media was partisan and biased. And certainly many people in my social media streams were partisan – refusing to face up to the way the US establishment manipulated the election process (successfully in the case of the Democrats) and willfully allowing themselves to be diverted and manipulated by cynical neo-McCarthyism.

But why blame the voters – especially if it was a choice between two evils? Why not blame the system that delivered such a limited choice to voters?

I could go on – but Thomas Frank’s article in the Guardian today certainly says it more eloquently than I can – Donald Trump is moving to the White House, and liberals put him there.

Is Trump all bad?

Frank starts by ripping into Trump and his campaign. Many will agree with his criticisms – although the fact Trump succeeded suggests the possibility he may have known something his critics didn’t, or understood the mood of the electorate better than his critics did.

Frank considers the election result “is a disaster, both for liberalism and for the world.” Again, Frank may be exaggerating. I think he is a buffoon but if Trump’s policies of real international cooperation in the fight against terrorism and getting along with other countries become realities I consider that a positive.

But instead of expanding on what is wrong with Trump, Frank asks the questions others have been afraid to ask.

Why Clinton?

The electorate was in a mood to punish the establishment – so why put up an establishment candidate? Frank puts it this way:

“What we need to focus on now is the obvious question: what the hell went wrong? What species of cluelessness guided our Democratic leaders as they went about losing what they told us was the most important election of our lifetimes?

“Start at the top. Why, oh why, did it have to be Hillary Clinton? Yes, she has an impressive resume; yes, she worked hard on the campaign trail. But she was exactly the wrong candidate for this angry, populist moment. An insider when the country was screaming for an outsider. A technocrat who offered fine-tuning when the country wanted to take a sledgehammer to the machine.

“She was the Democratic candidate because it was her turn and because a Clinton victory would have moved every Democrat in Washington up a notch. Whether or not she would win was always a secondary matter, something that was taken for granted. Had winning been the party’s number one concern, several more suitable candidates were ready to go. There was Joe Biden, with his powerful plainspoken style, and there was Bernie Sanders, an inspiring and largely scandal-free figure. Each of them would probably have beaten Trump, but neither of them would really have served the interests of the party insiders.

“And so Democratic leaders made Hillary their candidate even though they knew about her closeness to the banks, her fondness for war, and her unique vulnerability on the trade issue – each of which Trump exploited to the fullest. They chose Hillary even though they knew about her private email server. They chose her even though some of those who studied the Clinton Foundation suspected it was a sketchy proposition.

“To try to put over such a nominee while screaming that the Republican is a rightwing monster is to court disbelief. If Trump is a fascist, as liberals often said, Democrats should have put in their strongest player to stop him, not a party hack they’d chosen because it was her turn. Choosing her indicated either that Democrats didn’t mean what they said about Trump’s riskiness, that their opportunism took precedence over the country’s well-being, or maybe both.”

A biased and manipulating media

Frank also blames the media – and in my view rightly so. Even with my limited appreciation of politics the media bias and manipulation stood out like a sore thumb:

“Clinton’s supporters among the media didn’t help much, either. It always struck me as strange that such an unpopular candidate enjoyed such robust and unanimous endorsements from the editorial and opinion pages of the nation’s papers, but it was the quality of the media’s enthusiasm that really harmed her. With the same arguments repeated over and over, two or three times a day, with nuance and contrary views all deleted, the act of opening the newspaper started to feel like tuning in to a Cold War propaganda station.”

After listing some of the medias biased pro-Clinton propaganda Frank says:

“How did the journalists’ crusade fail? The fourth estate came together in an unprecedented professional consensus. They chose insulting the other side over trying to understand what motivated them. They transformed opinion writing into a vehicle for high moral boasting. What could possibly have gone wrong with such an approach?”

I think this post-election media comment is very relevant – The media didn’t want to believe Donald Trump could win… So they looked the other way.

Where my social media friends went wrong

What has amazed me, and taught me a lesson (I guess), is how irrational some of my Facebook friends were about this election. And these were people I had friended because on many issues (particularly scientific ones) I considered them rational and unbiased. In the end we are not a rational species and wishful thinking, confirmation bias and avoidance of self-criticism are only human traits. But Frank describes this self-delusion as “the single great mystery of 2016:”

“The American white-collar class just spent the year rallying around a super-competent professional (who really wasn’t all that competent) and either insulting or silencing everyone who didn’t accept their assessment.”

That insulting and silencing were very real. I experienced the shouting down when I criticised Clinton’s dishonest use of neo-McCarthyist tactics to divert attention aways from her faults. Critics, and even the ordinary people, were insulted and, yes, silenced by this intimidation. Frank points out – “And then they lost.” We are now forced to face up to facts – the emperor really has no clothes.

But I  hope at least some of those social media friends who were caught up in the wishful thinking and group thinking – the partisanship of the US elections – can take on board this bit of advice from Frank:

Maybe it’s time to consider whether there’s something about shrill self-righteousness, shouted from a position of high social status, that turns people away.”

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Fluoridation debate: Responding to Tom O’Connor

This is the second article in the debate between Tom O’Connor and me. It is a response to his post Debating fluoridation and tyranny – Tom O’Connor responds).

I think Tom’s concept of “freedom of choice” is confused. He appears to be arguing for his own right to determine a social decision. But that is undemocratic, it imposes an individual’s wish on society.

We all have the freedom to influence, make submissions on, contribute to, etc., a social decision. In the end, that decision is made democratically. The minority does not have the right to use the individual’s “freedom of choice” argument to demand that decision not be democratic.

That is not the ‘tyranny of the majority”  Tom claims because on  most issues the individual still has the “freedom of choice” to make individual arrangments to satisfy their position. No one is being coerced and the individual can take personal responsibility for their own arrangements. This is particular true with community water fluoridation (CWF).

Tom and I have different values or politic outlooks underlying our different attitudes towards CWF.

Opposing values systems

I don’t want to put words in Tom’s mouth but in practically he is opposed to CWF despite the clear social benefits. He is claiming his personal “freedom of choice” is more important than the community’s – or at least the majority of the community.

In contrast, I support CWF because of its social benefits. However, I accept the obligation of governing bodies to consult the community when there is a controversy and support the decisions of the community (I also support the right of individuals and communities to make the wrong decision – within reason, of course).

In the most general terms, these boil down to issues of social responsibility vs individual or personal responsibility. Put simplistically, some would see the conflict a between a “socialist” or “libertarian” perspective. (I apologise for using labels.) These different values systems lead to different understandings of freedom of choice (and of being “forced”).

Given the stand of personal responsibility, as a personal values system, Tom should not need to seek the justification of advancing or questioning facts. He should simply stand on principle, and seek support for that principle. On the other hand, there is an obligation on people arguing for social responsibility. We need to show that the advocated social policy provides a net advantage to the community and/or individuals. If there are no advantages there is no point in such policies and the personal responsibility or “libertarian” position may as well stand.

Tom is welcome to his values system, and he no doubt says the same about me. We live in a pluralist society and most of us accept such differences are handled by the democratic process. I should also add that most people do not adhere to an absolutist “libertarian” or “socialist” approach and prefer a more balanced and sophisticated approach to social issues.

Society usually attempts to balance individual rights/responsibilities and freedom of choice against social responsibility. After all, individual rights and social responsibility are co-dependent. Our individual rights and freedom of choice cannot survive where our freedom, rights, health and well-being are not supported by sensible social policies.

A democratic social decision may appear to result in the loss of that freedom of choice. After all, I can express my freedom of choice to have a Green government, but after the election I have to accept that freedom is put on hold for another three years and in the meantime I have to put up with a National-led government. But that does not deprive me of the freedom to advocate for policies underlining my preference for the Greens – and under MMP such advocacy can be effective even between elections.

Similarly, the minority in a decision on CWF does not lose personal “freedom of choice.” If they are willing to take personal responsibility for their situation they can with very little effort, make personal arrangements. Those with a hangup about fluoride can use to filters or alternatives sources. Those who wish to use fluoride can resort to mouth rises or alternative water sources. In taking these actions we are exerting our freedom of choice.

Tom has stepped outside the ethical issues to argue some statements of fact which need challenging.

Raising doubt and the balance fallacy

Tom asserts:

“Both sides have accused the other of engaging in pseudo-science and scare mongering. Both are, to some extent, probably accurate and in agreement on that point alone. However, where doubts exist, it is probably better to err on the side of caution.”

Putting “both sides” into the same box of “engaging in pseudo-science and scare mongering” is a Clayton’s argument. A claim made without any substantiation but appealing to “balance” nad “fairness. Rather than relying on such “warm fuzzies” Tom should present the examples and evidence if he wishes to make such claims.

Similarly, unsupported claims of doubts and the need for caution can be a way of discounting the science and its quality. Hence, the emotional slogan “if in doubt, leave it out!” Society should make decisions based on evidence, not warm fuzzies and catchy slogans.

We are familiar with the financially and ideologically motivated purposeful raising of doubt on issues like the science regarding tobacco use and climate change.  Merchants of Doubt by Oreskes and Conway provide a good description of such dishonest tactics – and the title is very appropriate.

Drinking water standards

Tom claims:

“The principle responsibility of local authorities, as outlined in the Drinking Water Standards for New Zealand, administered by the Ministry of Health, is to ensure drinking water is as free from all other substances and organisms as possible.”

Where do the standards say that, Tom? My checking of Drinking Water Standards for New Zealand produced these principles:

“all water suppliers have a duty to ensure their water is safe to drink.”


“all drinking-water suppliers providing drinking-water to over 500 people must develop and implement a water safety plan (originally known as a Public Health Risk Management Plan, PHRMP) to guide the safe management of their supply. This quality assurance approach is complemented by the DWSNZ, which specify the maximum acceptable concentrations of harmful contaminants in the water.”

What these standards do is set maximum acceptable values (MAVs) for a whole list of possible “harmful contaminants” – occurring naturally or from the water treatment itself. Think about it – no realistic body would set standards demanding water was “free from all other substances and organisms as possible” – leaving interpretation up to the individual operator!

Of course, individuals may want to lower these MAVs (or even make them zero) – but they are derived from the best available science and practical considerations. If individuals are unhappy they can, of course, challenge the standards. But they do not have the “freedom of choice” to arbitrarily  replace them with their own personal values. They do have the freedom of choice to use other water sources or tap filters. That is the sensible and responsible thing to do, rather than childishly demand a change just to satisfy their own hangup.


This involves additions to water that Tom has absolutely no control over. Why does he not object to that addition on his ethical stance that he has the “freedom of choice” to control what goes into community water supplies?

Personally, I would oppose chlorination  long before I objected to fluoridation because irrespective of whether there is any detectable chlorine “at the end of the process” (there should be),  chlorine can react with naturally occurring organic material to produce possible hazardous or carcinogenic compounds. That is why local authorities check for these in our water.

My city uses UV irradiation for the early disinfection process and only adds chlorine at the end so that the tap water remains organism free. But if I lived in a city where the first disinfection use chlorine I would seriously consider using a tap filter to remove possible hazardous compounds.

Iodised salt

Tom is OK with the “mass medication or treatment” involved in iodised salt because there is “always un-iodised salt as a practical, convenient and affordable option on grocer shop shelves for those who did not want it.”

Does he bother to exert that “freedom of choice” when he shops? Has he even checked the availability of uniodised salt? I checked the other day and my supermarket had plenty of iodised salt but no specifically non-iodised salt. It had boutique salts (even “chemical free” salt) and I imagine the chemophobic shoppers might prefer those products to iodised salt – not realising they also contain iodine.

This can get silly. There are anti-fluoride people who treat their water by reverse osmosis – then replace the removed minerals by adding Tibetan salt which contains fluoride (and is sometimes sold as “chemical-free.”

Folic acid

I would willingly support mandatory folic acid fortification. More countries will probably do this in future because the evidence is pretty clear that it helps prevent the tragedy of neural tube defects. It seems a sensible approach because of the need for folic acid at the stage of pregnancy where the mother may be unaware.

At the moment, New Zealand has a voluntary folic acid fortification system. About 17% of packaged bread was fortified with folic acid in 2012. The industry is working towards fortification levels of 50%  – with at least 25% meant to be achieved by the end of 2014.

Tom, you appear to oppose folic acid fortification. Do you check your bread packaging to check it hasn’t been fortified? I suggest hardly anyone does so.

There are lots of things individuals can have hangups about. Some people object to chlorination. Some to pasteurized milk. Given that society does set standards for our food and water it is inevitable individuals may sometimes have to take personal responsibility and check the food and water they purchase. But I cannot understand the directed concern over fluoride as it is one of the easiest things to check and make personal arrangements for.

While I had plenty of choice at my supermarket if I wanted “fluoride-free” water. I had no choice if I wanted “iodine-free” salt” or unpasteurized milk. If I had a hangup about folic acid I would need to make the effort to carefully scrutinise bread packaging to find “folic-free” bread. And do that often because of plans to increase folic acid fortification of bread over time.

Removal and personal responsibility

Tom really should back up this claim:

“Suggesting that those who object to fluoride in the water they pay their local authority to deliver can obtain alternative supplies from a community tap or buy it from the supermarket is unacceptable. These options are not possible, practical, convenient or affordable for many people.”

What about some monetary figures to claim alternatives are not affordable? Frankly I do not think he has a leg to stand on here as people who choose to opt out of our secular education  and free hospital systems face far bigger financial costs. In my experience most anti-fluoride campaigners already take such steps for themselves and when pressed claim they are speaking up for others less fortunate than themselves. Yeah, right!

Tap filtration practical and convenient. “Fluoride-free” water is readily and cheaply available (more so than unpasteurised milk and non-iodised salt I have found). And the slight inconvenience involved is of little consequence to someone who really believes the anti-fluoride story.

Incidentally, several cities provide “fluoride-free” community taps. the fact these get very little use suggests to me that those who are really concerned already have more convenient arrangements.

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Once more on the IQ and fluoride myth – why ignore other factors?

The “fluoride damages IQ” myth won’t go away – mainly because it is avidly promoted by campaigners against community water fluoride (CWF). This is despite the fact that no link has even been drawn between CWF and IQ (the only relevant study shows no connection). But that doesn’t stop ideologically driven campaigners who rely on poor quality studies from areas of endemic fluorosis where dietary fluoride intake is higher than in areas using CWF.

There are plenty such studies, but a more recent one illustrates their problems – and the role  confirmation bias seems to play in these studies. It is:

Kundu, H., Basavaraj, P., Singla, A., Gupta, R., Singh, K., & Jain, S. (2015). Effect of fluoride in drinking water on children′s intelligence in high and low fluoride areas of Delhi. Journal of Indian Association of Public Health Dentistry, 13(2), 116.

It’s another study where the IQ values of children from a “high fluoride” area were compared with those for children from a “low fluoride area.” There was a statistically significant difference and the paper goes on to claim:

“High F concentration in the drinking water was found to have marked systemic effects on the IQ of children. Though the precise mechanism by which F crosses the blood brain barrier is still not clean‑cut; enough evidence survives for the influence of F intake via drinking water and low IQ of the child.”

However they do acknowledge:

“Apart from fluoride there are other factors which also affect IQ of children. In the present study, mothers diet during pregnancy also significantly affected the IQ of the children.”

The supporting data is poorly presented and described – for example, no indication is given of the fluoride concentration in the drinking water of the “high fluoride and “low fluoride” areas used. Although they do cite areas in Delhi (where the study was located) with fluoride concentration as high as 32.5 ppm!. And I cannot find any details on “mothers diet during pregnancy” (except perhaps division into two groups – “routine” or “special diet as suggested by the doctor during pregnancy”).

Those confounding factors

These sorts of studies almost always rely on finding a statistically significant difference in the IQ values of children in two different areas or villages. But that statistical significance says nothing about the causal factors involved – it may have nothing to do with differences in fluoride levels.

Kundu et al., (2015) do at least include some data on confounding factors which is often missing from such studies. These show significant difference between the groups from the “high fluoride” and “low fluoride” areas which have no connection with fluoride in drinking water – such as father’s occupation, mother’s education and father’s education) – or only an indirect connection (dental fluorosis).

Here is a summary of the data for the various factors. I have selected the data so to show as two values – equal to “high fluoride” and “low fluoride.”


You get the picture. The areas were chosen according to the concentrations of fluoride in drinking water (whatever they were), but they could equally have been chosen on the basis of parental education, father’s occupation or prevalence of the more severe forms of dental fluorosis.

In fact, rather than concluding drinking water fluoride has a “marked systemic effects on the IQ of children” we could equally have concluded:

  • “The father’s occupation has a marked effect on the IQ of children with the children of unskilled fathers having a lower IQ.”
  • “The mother’s and father’s education has a marked effect on the IQ of children with the children of parents with a higher education having a higher IQ.”
  • “Diet of mothers during pregnancy has a marked effect on the IQ of children.” (The paper did not include data suitable for plotting for this.)

The dental fluorosis factor interests me as I have suggested that, in areas of endemic fluorosis, the physical appearance of defective teeth could lower quality of life and cause learning difficulties which are reflected in lower IQ values (see Severe dental fluorosis the real cause of IQ deficits?Severe dental fluorosis and cognitive deficits – now peer reviewed and Free download – “Severe dental fluorosis and cognitive deficits”).

I think that this is more reasonable as a mechanism than the chemical toxicity mechanism that almost all authors of these sorts of papers assume – but never support with any evidence. Even when dental fluorosis is considered it is usually treated as an indicator of lifetime intake of fluoride (which it is) rather than and independent cause of low IQ.


Most studies like this seem to be motivated by confirmation bias. Despite the possibility of a range of factors being involved, and some of these such as parental education being a more obvious cause, there appears to be an urge to interpret data as evidence of a chemical toxicity mechanism involving fluoride. And there is never any experimental work to confirm this preferred mechanism.

To my mind, if fluoride is implicated in the low IQ values the mechanism involving effects of dental fluorosis on quality of life and learning difficulties appears more credible than an unproven chemical toxicity.

Note: None of this is directly relevant to areas where CWF is used. The prevalence of more serious forms of dental fluorosis is very small in these areas and not related to CWF. Also, no study has yet found an effect of CWF on IQ. Given the higher levels of fluoride used in the studies from areas of endemic fluorosis, and the higher levels of serious forms of dental fluorosis, extrapolation of the results to areas where CWF is used is completely unwarranted.

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