Category Archives: Science and Society

New research confirms water fluoridation does not cause bone cancers

Osteosarcoma
The most common type of bone cancer is Osteosarcoma. Image credit:  Osteosarcoma

This time for Texas.

A new study confirms what other researchers have found elsewhere. It is reported in this recent paper:

Archer, N. P., Napier, T. S., & Villanacci, J. F. (2016). Fluoride exposure in public drinking water and childhood and adolescent osteosarcoma in Texas. Cancer Causes & Control

The paper concludes with this statement:

“No relationship was found between fluoride levels in public drinking water and childhood/adolescent osteosarcoma in Texas.”

The same conclusion has been drawn in many reviews of the literature. For example, a local review:

Broadbent, J., Wills, R., McMillan, J., Drummond, B., & Whyman, R. (2015). Evaluation of evidence behind some recent claims against community water fluoridation in New Zealand. Journal of the Royal Society of New Zealand, 6758(October), 1–18.

They pointed out that Bassin et al., (2006) “found a small but
statistically significant association with fluoridated water among the 60 cases [of osteosarcoma]  that occurred among males.”

Anti-fluoride campaigners have relied on this study, even though Bassin et al., (2006) had acknowledged methodological issues with their analysis and urged caution in interpreting their findings. Broadbent et al., (2015) say:

“The work of Bassin et al. (2006) stimulated further, more comprehensive research; however, the new studies have not replicated their findings.”

This conclusion was based on the findings of Kim et al. (2011), Comber et al. (2011), Levy & Leclerc (2012) and Blakey et al. (2014).

The New Zealand Fluoridation Information Service (2013) drew similar conclusions from their review of the literature but also checked out the New Zealand data. They reported in Community Water Fluoridation and Osteosarcoma:

“The analysis confirms that osteosarcoma is extremely rare in New Zealand with only 127 new cases registered during this period averaging 14.1 per year. The peak age is 10 to 19 years for both sexes. These rates indicate that there is no difference in the rates of osteosarcoma cases between areas with CWF [community water fluoridation] and areas without CWF for both sexes,”

The authoritative New Zealand Fluoridation Review (Eason et al., 2014. Health effects of water fluoridation : A review of the scientific evidencealso drew the same conclusion:

“We conclude that on the available evidence there is no appreciable risk of cancer arising from CWF.”

So, once again community water fluoridation has been found safe and a published study suggesting otherwise not confirmed. But I am betting this will not stop anti-fluoride campaigners continuing to cite the Bassin et al. (2006) study as the last word on the topic and “proof” CWF causes osteosarcoma.

Note: For the pet lovers out there.

PetsWelcome

You can also be reassured by this recent study:

Rebhun, R. B., Kass, P. H., Kent, M. S., Watson, K. D., Withers, S. S., Culp, W. T. N., & King, A. M. (2016). Evaluation of optimal water fluoridation on the incidence and skeletal distribution of naturally arising osteosarcoma in pet dogs. Veterinary and Comparative Oncology.

This concluded:

“Taken together, these analyses do not support the hypothesis that optimal fluoridation of drinking water contributes to naturally occurring [osteosarcoma] in dogs.”

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Public discussion of science can be toxic

Public discussion of the science around problems humanity faces today seems inevitably to be diverted by hostility, misleading propaganda, personal attacks, and even outright censorship* of scientists and supporters of science. This creates an atmosphere, and an information overload, which turns the ordinary person off –  if it doesn’t actually fool them into taking up an unscientific position.

So I welcome the publication of the new book I’m Right and Your an Idiot. Subtitled The Toxic State of Public Discourse and How to Clean it up, the book which is launched next week, looks like it will help scientists and supporters of science who regularly confront this problem.

James Hoggan, the author, is a co-founder of the website, DeSmog, which is well known for its activity in disseminating the real science about climate change. So it is significant that the Amazon blurb for the book starts with this:

“The most pressing environmental problem we face today is not climate change. It is pollution in the public square, where a smog of adversarial rhetoric, propaganda, and polarization stifles discussion and debate, creating resistance to change and thwarting our ability to solve our collective problems.”

In the book, Hoggan explores:

“How trust is undermined and misinformation thrives in today’s public dialogue. Why facts alone fail – the manipulation of language and the silencing of dissent. The importance of reframing our arguments with empathy and values to create compelling narratives and spur action.”

The blurb finishes with this very relevant point:

“Our species’ greatest survival strategy has always been foresight and the ability to leverage our intelligence to overcome adversity. For too long now this capacity has been threatened by the sorry state of our public discourse. Focusing on proven techniques to foster more powerful and effective communication, this book will appeal to readers looking for both deep insights and practical advice.”

James Hogan is also the author of Climate Cover-Up and Do the Right Thing.

*NoteI think anti-science hysteria can create its own censorship, quite apart from government,  where ideologically motivated activists seek to exclude scientists from debates. This was brought home to me recently when I joined a Facebook group, Methven Fluoride Facts, which has the declared aim:

“This is a place to come for facts about fluoride. Everyone is welcome. We would like facts only. Please refrain from personal attacks on others, this will not be tolerated. This is simply about educating the community in a safe forum.”

I spent the first day answering questions and  attempting to correct some of the scientific misunderstandings on the group posts. Then I was subjected to a frenzy of anti-fluoride memes, accusations of being a shill and a troll, hostile comments and finally banned from the group. Administrators of this group tolerated the science for only two days! And their actions help censor scientific input from other members of the group.

(Come to think of it, I must have been banned from almost every anti-fluoide social discussion group I have ever commented on – and I don’t think it is just me).

These days internet forums, blogs, and social media are an important place for the public discussion of issues.  When such forums fall under the control or pressure of anti-science groups they can seriously distort the discussion by censorship like this.

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Fluoridation cessation studies reviewed – overall increase in tooth decay noted

Anti-fluoride activists love to trot out studies where no increase in tooth decay was found after community water fluoridation  (CWF) ceased. They are cherry-picking, of course, because they ignore the studies which do show a decline in dental health. I have written about this before in What happens when fluoridation is stopped? and Anti-fluoridationist’s flawed attacks on Calgary study.

So I am pleased to see a new, just published, review of fluoridation cessation studies. Also pleased that it confirms my impression of the literature.

In short, this review concluded that:

“Overall, the published research points more to an increase in dental caries post-CWF cessation than otherwise.”

The study is published in this paper – it’s open access so you can download a pdf or see the full text:

Mclaren, L., & Singhal, S. (2016). Does cessation of community water fluoridation lead to an increase in tooth decay ? A systematic review of published studies. J Epidemiol Community Health 2, 1–7.

Unsurprisingly, these sort of studies have problems – humans cannot be treated as laboratory rats. Researchers must rely on ordinary data for dental health collected before and after cessation.

Nevertheless, these researchers managed to find 15 instances of cessation occurring in 13 countries and reported in 29 publications. Several of these were excluded because they did not consider specific cessation effects  but reported on the enduring benefits of CWF even after cessation when children were exposed to CWF in the first 4 years of life. Evidence supporting a beneficial systemic effect of CWF in developing teeth. Another instance was excluded because of the complexity of its reports results didn’t enable any conclusion about effects.

Of the remaining situations, eight showed an increase in tooth decay after CWF was stopped. These occurred in Europe, Asia and North America. This paper was obviously submitted before the publication of the Calgary cessation study (Measuring the short-term impact of fluoridation cessation on dental caries in Grade 2 children using tooth surface indices) which also showed an increase in tooth decay (see Anti-fluoridationist’s flawed attacks on Calgary study for a discussion of this paper). So there are really nine instances showing an increase in tooth decay.

The other three instances did not show an increase in tooth decay. These occurred in East Germany, Finland and Cuba. These last three are, of course, the only studies anti-fluoridationists ever mention.

It’s worth quoting an observation from the paper which could help explain these different results:

“Importantly, in all three interventions, there were other factors which could have contributed to findings observed. In Finland, the CWF-cessation community started to provide fluoride tablets to children postcessation. In East Germany, postcessation fissure sealants were paid for by statutory health funds. In Cuba, postcessation, all children received fluoride mouth rinses fortnightly, and children aged 2–5 years received 1–2 fluoride varnish applications annually. Those initiatives could have offset an impact of cessation on dental caries.”

This is a really useful review as the cessation literature has not been properly reviewed before. For example, the recent Cochrane Review only considered one cessation study and concluded: “there is insufficient information to determine the effect of stopping [CWF] on caries levels.” The authors stress the need for researchers to take advantage of research opportunities presented by CWF cessation.

The authors stress the need for researchers to take advantage of research opportunities presented by CWF cessation ( there is a lot of it about in some countries). The also say there is a need for information on how cessation impacts different socio-economic groups and how decisions about cessation are made.

CWF cessation studies are just one area where anti-fluoride campaigners cherry-pick the literature. This example underlines why readers must always treat claims made by these campaigners critically. Always look at the original studies, the data, other treatments, etc.  And check other research these campaigners are hiding.

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Mistakes were made – but by who?

36-chesterfield-cigarettes-are-good-for-you-ad

How often do we see ads like this promoting a product by claiming scientific support that doesn’t exist. All in the interest of profit.

We are all wrong at times – usually a lot more often than we think, or are happy to acknowledge. But the only person who doesn’t make a mistake is the person who is not doing anything – and that is a mistake in itself. Humanity didn’t get where it is today by refusing to act on our best knowledge – even when realising that our knowledge is inevitably  imperfect.

So why do people sometimes resort to the argument that science has made mistakes? They certainly cannot suggest a better alternative. I can only conclude they do this to attack a current scientific consensus they disagree with. A pathetic argument but one often used. Particularly by people who don’t have a scientific leg to stand on.

The trope of scientific mistakes

The Skeptical Raport put it this way in a recent article (Debunking the “mistakes science made” tropes?:

“The antivaccinationists, creationists, anthropogenic global warming deniers, and whomever else pretends to use science to actually deny science frequently focus on a trope covering the mistakes science made.  And then they produce a list of historical events that “prove” that science is wrong. Of course, this indicates more of a misunderstanding of what is science and the history of science than it is a condemnation of science. But your typical science denier is probably not going to let facts get in the way of maintaining faith in their beliefs.”

The article spends some time discussing the nature of scientific knowledge and the scientific method. It states:

“Yes, science does find errors, all the time. In fact, one of the goals of the scientific process is precisely what defines scientific skepticism, a term frequently co-opted by science deniers, which is a process of evaluating a claim based on the quality and quantity of evidence supporting that claim. A real scientist (or scientific skeptic) is looking for errors, because it is a part of the process.”

The excitement of finding a mistake

Working scientists will know the excitement that comes with finding one’s first ideas have been proven wrong by experiment. Or that we can show that a published scientific idea has just been destroyed by our experiment. Mistakes and incorrect hypothesis are exciting when we find them because they open the door to a better, more complete, knowledge that we can be responsible for.

This searching for, and discovery of, mistakes is an important driver for the improvement of scientific knowledge:

“Because science is not based on dogma or faith, it is self-challenging and self-critical, uncovering errors is part of the process that makes good science. And science is unbiased. The proper method of science is not to invent a conclusion, then find evidence that supports it. It actually works by gathering all of the evidence, deciding which is high quality and which is junk, then determining where that evidence leads.

“And as opposed to science deniers, who think that they have the one truth, real science makes mistakes and uncovers it rather rapidly.”

The smoking is healthy myth

The article goes on to discuss several  examples used by those who wish to claim that science is often wrong. I will only deal with the “Science said smoking is healthy” myth – it is one often used by anti-fluoride and anti-vaccination campaigners. The article says:

“But really, did any real scientist claim that smoking was healthy?Smoking tobacco was prevalent through the native American tribes well before the advent of modern science. There was no Native American CDC, FDA or Board of Physicians to approve the use of tobacco as “safe and effective.”

In fact, those Native Americans and Europeans who picked up the habit believed in all kinds of nonsense about tobacco, including that it cured cancer. This wasn’t “science” pushing these beliefs, but it was the traditions of the world at the time that put inordinate faith in various herbs and how they could cure various maladies. In fact, thinking smoking or tobacco was healthy was advertised by the woo-pushers of the time (who are barely different than the woo-pushers of the modern world).

An article inThe Lancet in 1913 warns “that tobacco smoking can give rise to constitutional effects which diminish the resisting power of the body to disease”

“By the 1930’s, real science observed the increase in lung cancer from smoking. The Nazis banned cigarette smoking in the 1930’s because of the known health effects. . . . In 1950, the Journal of the American Medical Association published an article by Martin Levin that linked smoking and lung cancer. By the mid-1950’s, numerous epidemiological studies showed a profound increase in lung cancer risk for smokers. The Royal College of Physicians (UK) warned against smoking in 1962. The Surgeon General of the USA warned against smoking in 1964. The CDC has warned against smoking for over 50 years.”

“Yes, tobacco advertisers used to make ads that showed doctors smoking, or worse, endorsing cigarettes. But that wasn’t the “science” of the time. Big Tobacco (a truly evil lot of characters) said just about anything to get people to smoke, whether it was showing doctors smoking or that smoking made you sexy. But they weren’t using peer-reviewed science, these ads were worse than anecdotes, because they were outright lies and mischaracterizations. Science had already concluded that cigarettes were unhealthy a half century before those ads.”

“Once real epidemiological studies were published in peer-reviewed journals, the attitude about smoking changed almost immediately in the medical and general scientific community. And that’s how real science works–it self-corrects.”

As the author says of this particular myth:

“As a suggestion to the science deniers–quit using this trope. It shows how ignorant you are of history, the scientific method, and reality.”

Blaming science for the errors of others

Often these myths about scientific errors boil down to inability to see who made the real errors.  The article quotes Emily Willingham who wrote the following about science in an article in Forbes:

“That said, other ways of viewing of our world clearly carry greater weight for people than science or evidence does. If evidence and data were the only factors in human decision-making, the epic debates humans engage in about whether vaccines eradicated smallpox or whether global climate change is real wouldn’t exist. Even though science is the ultimate lens for truly understanding what underlies our entire existence, we obviously use other, frequently more myopic lenses available to us.

And that leads me to the faults of science. Humans do science, and because we bring our own personalized lenses and biases to whatever we do, science will involve error. But the wonderful thing about science is that it’s a self-correcting process that over time, disciplines itself. How did we discover the real effects of tobacco or DDT that ultimately were revealed? Science made those revelations, and science provided the data everyone needed to know the truth.”

Let’s acknowledge up front that science makes mistakes. But let’s also acknowledge that anti-science campaigners are using these myths inappropriately – blaming science for social mistakes made by governments, business interests or other opinion drivers in society.

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Don’t be fooled by simple media “science”

This video is getting plenty of coverage – and despite its length, it is worth watching. The humour helps, of course. You certainly won’t be bored if you commit the 20 minutes required to watch the video right through.

Oliver warns about the way journalists often misrepresent the science. Further, he is warning that often the science itself is suspect – or even no good.

It’s a warning we should all take on board. If we are interested in understanding something, and not just cherry-picking to confirm an existing ideological bias, then we have to approach what we read in the media about science critically and thoughtfully. Not accepting things at face value. Nor interpreting a journalist attempt at a false balance as somehow authenticating an article.

Hell, all good working scientists know that we should approach the peer-reviewed scientific literature itself in the same critical way. So we should hardly be more gullible when it comes to the media reporting of science.

I do get annoyed at the way our media often presents scientific issues in simplistic and shallow ways.

But then again, I also get very annoyed at the way our media presents important political issues in the same way – or even worse. Just look at the disgraceful way our media covers important issues like the war in Syria.

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“Do the math” – a bit like “Do the research!”

ChCh press letterCherry-picking data is an old technique used by those who wish to raise doubt about a scientific consensus. On the one hand, it isolates the cherry-picked data from their context and the rest of the data. On the other hand is present a “sciency” authority to the argument by pretending to be evidence-based.

I have written about cherry-picking in several articles discussing the fluoridation issue – so nothing new here. But the current surge of activity by anti-fluoridation activists  attempting to raise doubt with the upcoming parliamentary discussion of new legislation on fluoridation is producing a fresh wave of cherry-picked arguments.

The image here is just one example in a letter to the Christchurch Press a few days ago. I thought it worthwhile to actually check out the quoted figures to see if the arguments awere justified.

Firstly, the figures were taken from the Ministry of Health’s 2014 data for the dental health of New Zealand children. Unfortunately, while the actual numbers used are correct, the data has since been withdrawn because of errors in the spreadsheet. So I will use the data for earlier years,  2005 – 20013, in my analysis.

The overall picture

First off – the overall picture shown by the Ministry of Health data is that community water fluoridation does reduce tooth decay. Of course, that is why the anti-fluoride campaigner rarely discusses the overall picture – instead, they cherry-pick data to confirm their bias. The figure below is for 5-year-olds  averaged over the years 2005-2013

MoH-overall

I have separated the data by ethnicity because of the big differences Māori and Pacifica on the one hand and the other ethnic groups on the other. In particular, the dental health of Māori and Pacifica children is poorer. This is an important factor which needs to be taken into account when comparing data from different regions. I discussed this further in my article Anti-fluoridation cherry-pickers at it again.

Data for Canterbury

It is likely that at least some of the 2014 spreadsheet mistakes were in the Canterbury data – but still the claim that there is no real difference between data for fluoridated and non-fluoridated areas could well be true – at least for some years. The figure below displays the data for 5-year-old children. Choose your year and you will get the answer you want to confirm your bias. Children from fluoridated areas seem to have poorer teeth in 2008 and 2010 and better teeth in 2012 and 2013.

Canterbury-5-years

MoH 5-year-old child dental health data for 2005-2013. dmft = decayed, missing and filled teeth.

The plots in the above figure indicate how unreliable such comparisons are for Canterbury because the fluoridated data is all over the place. This is because of the very low number of children in the fluoridated area: 22 – 70 over the years, 42 on average. There were on average 4720 children in the non-fluoridated areas. Children from the fluoridated area usually comprised less than 1% of the total.

The data for Canterbury does not deny the effectiveness of fluoridation, as the letter writer claims. They just show that no conclusion can be drawn from this cherry-picked data. At least I cherry-picked the data from 2005-2013 which enabled me to see how unreliable they were. The letter writer just cherry-picked one year! What will they do if the corrected spreadsheet for 2014 no longer supports their bias – switch to 2010 instead?

Comparing Canterbury and Waikato data

Here we have a different problem. The letter writer has simply cherry-picked these figures because they confirm her bias. She has not taken into account the important influence that ethnic composition has. Any intelligent analysis of this comparison must consider this aspect.

This is the ethnic composition of the 5-year-olds MoH data (averaged over 2005-2013).

Canterbury Waikato
Māori (%) 10.2 31.5
Pacifica (%) 3.2 2.1
Other (%) 86.6 66.4

So, whereas only 13.4% of Canterbury 5-year-olds are Māori or Pacifica, 33.6% of Waikato 5-year-olds are Māori or Pacifica. This is an important difference – especially as the dental health of Māori and Pacifica is poorer than others as demonstrated in the first figure .

Any analysis that does not take this difference into account will be misleading.

As well as ethnic distribution between regions there is also the influence of ethnic distribution between the fluoridated and non-fluoridated areas. This was a factor I discussed in Anti-fluoridation cherry-pickers at it again. The graphic below for 5-year-old children shows Māori and Pacifica are more concentrated in the fluoridated Waikato areas than in the non-fluoridated ones.

MoH-ethnic

Distribution of Māori and Pacifica between fluoridated and non-fluoridated areas.

We can ignore the bar for fluoridated Canterbury because of the very small numbers.

What this means is that the mean value for fluoridated Waikato areas is decreased by the higher presence of Māori and Pacifica than in the non-fluoridated Waikato areas. This higher proportion Māori and Pacific in the Waikato region also affects the comparison of the two regions made by the letter writer.

Rather than comparing oranges with apples, let’s compare Canterbury and Waikato for the same ethnic group – Others (not including Māori and Pacifica). As the figure below shows, removal of the effect of Māori and Pacifica from the Canterbury data increase the caries-free percentage – but it is still slightly less than the equivalent data for the fluoridated Waikato areas.

Waikato-Canterbury

So much for children from non-fluoridated Canterbury areas having better teeth than children from fluoridated Waikato areas.

Auckland and Counties/Manakau

Some anti-fluoride campaigners are pulling the same trick – asserting the dental health of non-fluoridated Canterbury children is better than for the fluoridated Auckland and Counties/Manakau children.

Here is a comparison of the ethnic composition of the three regions for the 2013 5-year-old MoH data.

% Māori + Pacifica
Canterbury

13

Auckland

32

Counties/Manakau

52

See the problem? It is just completely naive – or worse, dishonest – to compare data between regions like this without taking ethnic composition into account.

But that is not going to stop the determined activist who will just cherry-pick whatever fits their bias. I think the naive presentation of data in this way is no more justified by the declaration “Do the math” than misrepresentation of the science is justified by the declaration “Do the research!”

Note: I am well aware that the MoH data have other problems. A truly scientific analysis would also take into account factors like the degree of misallocation of children due to different fluoridation status of home and school, dental treatments such as fluoride varnishes differently used in different regions, missing data, different proportion of attendance according to region and ethnicity, etc. I am not the person to make such a thorough analysis. My sole purpose here is to show how such raw data can be misused for confirmation bias and “sciency” support of mistaken political agendas.

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Will we be using contact lens cameras in future?

contact_patent

A future contact lens camera – from a patent by Sony

A few decades ago I taught photography to night classes. We had no idea then that it would not be long before almost everyone would be carrying around a small camera in the form of a mobile phone. I couldn’t even get students interested in the concept of digitising their photos and processing or storing them on their computers.

It’s hard to predict the paths of new technology or its uptake by industry and the population. But I wonder if this new patent by Sony might give some insight to how we well take photographs in a few decades time. Just imagine – all it may take is to blink!

This article from Digital Photography Review, Sony patents contact lens camera with blink-triggered shutter, predicts privacy problems if the technology goes ahead.

The patented contact lens:

“comes with an integrated miniature camera module and all its components, such as image sensor, lens, processor, storage and even a wireless module to transfer images to a smartphone or other connected device. The camera is triggered by a “conscious” eyelid aperture and closure. A sensor measures the pressure of your eyelid, and other settings such as aperture and zoom can be controlled via eyelid movement as well. A display unit allows you to view captured images directly on the lens.”

So not any old blink will fire the shutter. Even so, I imagine there will be lots of accidental shots. And I have a picture of newbies pulling all sorts of facial expressions as they learn to apply just the right sort of pressure via their eyelid. Then there will be subjects who interpret the “conscious” blink as a wink!

As the article says:

“It’s impossible to know if a product like this will ever hit the market but if it does, it’s certain to raise even more privacy concerns than Google Glass at the time.”

The patent document is available here for anyone who enjoys torturing themselves with the convoluted language which seems unique to patents.

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Anti-fluoride campaigners cherry-pick irrelevant overseas research but can’t find relevant New Zealand research

fluorosis

Ever seen this in New Zealand?! Example of skeletal fluorosis from an overseas study used by local anti-fluoride campaigners to argue against community water fluoridation. Image Credit: Das et al., (2016)

Yes, I know. This is getting boring. A local anti-fluoride campaigner misrepresents research on fluoridation – yet again.

Perhaps I should apologise for yet another article debunking this sort of misrepresentation. In my defense can I just say this is just such a clear example that it can help drive the message home. These people cherry-pick research from areas of endemic fluorosis in China and India – pretend they are relevant to New Zealand or the USA – and ignore those studies which are relevant to countries which carry out community water fluoridation.

Stan Litras is (yet again) the guilty party. He has disseminated a press release, FIND cites new research, which will, of course, be reproduced by the Fluoride action network and make its way into the “natural”/alternative health media. That will, in turn, be cited by other anti-fluoride campaigners as “proof” that community water fluoridation is harmful!

Stan claims that:

“New research has confirmed that increased fluoride in water results in reduced intelligence. The research, published in the journal,of environmental monitoring and assessment, found that the higher the fluoride content in water, the lower the IQ of children, . . “

The paper Stan Litras relies on reports data from an area of endemic fluorosis in India. An area quite unlike New Zealand. Here is the citation for the paper (it’s a full-text version if you wish to check it out for yourself):

Das, K., & Mondal, N. K. (2016). Dental fluorosis and urinary fluoride concentration as a reflection of fluoride exposure and its impact on IQ level and BMI of children of Laxmisagar, Simlapal Block of Bankura District, W.B., India. Environmental Monitoring and Assessment, 188(4), 218.

Whatever its findings we can see how inapplicable that research is to New Zealand by comparing its data for dental fluorosis with similar data for New Zealand, USA and China. In this graphic below I compare prevalences of the mild forms (“none,”, “questionable,” very mild,” and “mild”) with the prevalences of “moderate” and “severe” forms. Only the latter forms are of concern (the milder forms are usually considered positively by adolescents and parents – see Water fluoridation and dental fluorosis – debunking some myths).

(Note: for a discussion of how severe dental fluorosis may influence IQ see Severe dental fluorosis and cognitive deficits.)

The figure  contrasts data for prevalence of dental fluorosis in NZ and theUSA where CWF is common with data for an area of endemic fluorosis in China and data from this paper (Das).

DF severe

While there is hardly any dental fluorosis of concern in USA and New Zealand these forms are very prevalent in the region of India covered by this study and a similar region of endemic fluorosis in China.

Or perhaps we should look at some more graphic evidence. Das et al., (2016) include the photo at the head of this article as an example of skeletal fluorosis found in the subjects they studied. And the photo below as an example of dental fluorosis found in their subjects.

DF Das 2016

Example of dental fluorosis observed by das et al., (2016) in subjects studied.

Come  on Stan – how often have you seen dental and skeletal fluorosis like this in New Zealand?

It is just not honest to cite this study in any discussion of the New Zealand situation. It has absolutely no relevance here.

To make this worse, Stan completely ignored New Zealand studies on these issues. For example the paper:

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

These researchers found no influence of community water fluoridation on IQ – see figure below.

NZ-IQ

Data from Broadbent et al., (2014)

So yes – just one more example of how local anti-fluoride campaigners are misrepresenting research on fluoridation. But a clear example of cherry-picking overseas studies irrelevant to community water fluoridation in New Zealand while, at the same time, ignoring New Zealand studies relevant to community water fluoridation.

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Cochrane fluoridation review described as “empty”

What-the-Cochrane-Review-Should-Have-Concluded

Image credit: MSoF – Ooops, [Newsweek] Did It Again

Publication of the Cochrane fluoridation review last year caused quite a flurry. Anti-fluoridation activists launched an avalanche of cherry-picked quotations and claims that completely misrepresented the review’s findings. On the other hand, the Cochrane review was poorly written and laid itself open to this cherry picking and misrepresentation.

Now, an authoritative group of authors has published a new critique which summarises the faults of the Cochrane review and shows how it has come to be misrepresented. The paper is:

Rugg-Gunn, A. J., Spencer, A. J., Whelton, H. P., Jones, C., Beal, J. F., Castle, P., … Zusman, S. P. (2016). Critique of the review of ‘Water fluoridation for the prevention of dental caries’ published by the Cochrane Collaboration in 2015. Bdj, 220(7), 335–340.

The on-line version is full text so readers can check it out for themselves.

The authors say:

“The Cochrane Review’s conclusion that ‘there is very little contemporary evidence. that has evaluated the effectiveness of water fluoridation for the prevention of caries’ is self-fulfiling due to its omission of contemporary studies designed for surveillance of public health programmes.

So they say:

“This, it could be argued, led to what is termed ‘an empty review’.”

And this is because a key problem of the review was “the restrictive inclusion criteria  used to judge adequacy of study design and risk of bias.”

Nature of water fluoridation programmes

A problem with the Cochrane review is that its judgement criteria were more suitable for drug trials than for evaluation of a social health policy. Drug evaluation relies on randomised controlled trials (RCTs), but:

“With public health interventions things are different. There will only sometimes be RCTs demonstrating efficacy and effectiveness. There are frequently no such trials because the highly complex practical, ethical and financial factors involved mean that RCTs are not feasible. Consequently, when determining whether a public health intervention is cost effective, evidence has to be drawn from a wide variety of other scientific methods and research designs including cross-sectional ones and process evaluations. . . . .

“In many cases it is simply impossible to make recommendations for public health interventions and policy if reliance is only placed on RCTs. Further, with public health interventions, the issue is not about individual patient benefit but whether the population as a whole will benefit.”

There are also many confounding effects with fluoridation:

“variations in use of other sources of fluoride, mainly from toothpaste, and diet, particularly sugar consumption. In many societies, these are closely linked to SES, and evaluation should also measure and control for these explanatory factors and interactions.”

Therefore:

“Water fluoridation should be evaluated using contemporary methods which are appropriate for evaluating public health interventions with such complexities, and systematic reviews should take this into account.”

The Cochrane review failed to do this and, although these problems were aired in the review’s discussion, the abstract and main conclusions were, therefore, misleading and open to misrepresentation.

Criteria for study inclusion

This “purist” approach was also demonstrated in the review’s criteria for study selection. The Cochrane authors considered:

“only prospective studies with a concurrent control, comparing at least two populations, one receiving fluoridated water and the other non-fluoridated water, with at least two points in time evaluated. Groups had to be comparable in terms of fluoridated water at baseline.”

But baseline data can be irrelevant when considering long-term fluoridation schemes. Rugg-Gunn et al., (2016) point out:

“Over time, in many countries, coverage of the population with water fluoridation schemes was almost complete, at least to the limits of public health requirements and technical feasibility. In such jurisdictions, the priority for health authorities was to monitor the continued effectiveness of existing schemes. Most recent evaluations of water fluoridation have been of this type, using the most appropriate design, which is a single cross-sectional survey of fluoridated and non-fluoridated groups with control for confounding factors.” One of the critical problems with the 2015 Cochrane Review is that these data have been excluded from the Review.

This, although recent evaluations have usually been of higher quality than older ones because of the availability of computer processing, use of more sophisticated statistical analysis and greater awareness of the need to taker confounding factors into account.

The authors discuss the impracticability of requiring baseline data for such long-term schemes. The Cochrane reviewers themselves stipulated baseline data should be taken within 3 years of implementing water fluoridation:

“an acknowledgement that the communities may, mainly through population change, lose comparability after three years. While this assumption of similarity may be reasonable over a short period, it becomes less tenable as the period between baseline and final examinations increases.”

This requirement looks silly when considering recent data from long-term schemes or considering possible benefits for 50-year-olds because:

“baseline information on the caries experience of people of this age would be required in the community to be fluoridated and in a comparable reference community, as well as information to be collected 50 years later on the caries experience of people from the same age group in the same communities which have continued to remain fluoridated or non-fluoridated for the whole of that very long period. Such requirements are unfeasibly stringent given the potential for community demographic characteristics to change over time, and render 50-year historical comparability of intervention and reference communities meaningless for present-day comparisons.[My emphasis]

Rugg-Gunn et al., (2016) discuss in-depth other aspects of the criteria used, exclusions if modern research by the Cochrane authors and study design.

Dental fluorosis

The Cochrane review’s inclusion of dental fluorosis seems to be “tacked on” and does not use the criteria outlined for their review and selection of caries studies. In particular, it ignored the influence of different sources of dietary fluoride – leaving the impression that the resulting data related to water fluoridation when it didn’t:

“In the Cochrane Review, the effect of water fluoridation on the prevalence of fluorosis should have been isolated from the confounding effect of other fluorides. The Cochrane Review’s analysis of fluorosis studies is silent on the possible contribution of other fluorides, such as fluoridated toothpaste, which risks leaving readers with the impression that all dental fluorosis arises from fluoride in water supplies. Research since 2000 has indicated that a greater proportion of dental fluorosis risk is due to the use (and therefore swallowing) of fluoride-containing toothpastes than to optimally fluoridated water.

Consequently, an intelligent interpretation of the fluorosis data in the Cochrane review requires some extra calculation – of the sort the reviewers themselves did for the caries studies:

“This comparison between intervention and reference communities was the method used for evaluating caries prevention in the Cochrane Review but, for an unexplained reason, not for the evaluation of dental fluorosis. For communities with lower fluoride concentrations (such as 0.5 mgF/L), their fluorosis levels should be compared with those in the corresponding reference (non-fluoridated) community.”

And

“The highly restrictive approach taken by the Cochrane Review in examining the effect of community water fluoridation on dental caries seems to have been abandoned for dental fluorosis. The reason for this difference is unclear.”

I attempted this “extra calculation” in my article Cochrane fluoridation review. III: Misleading section on dental fluorosis.”

When differences between “fluoridated” and “non-fluoridated” areas are considered there was no significant contribution of water fluoridation to the “dental fluorosis of aesthetic concern.” However, because  this comparison was not made in the Cochrane review anti-fluoride campaigners are claiming that fluoridation causes a prevalence of 12% “dental fluorosis of aesthetic concern!”

That is very misleading.

Anti-fluoride campaigners love to quote prevalence figures for all forms of dental fluorosis, not just the more serious – implying that even the mildest forms should concern us. Consequently, they cite the Cochrane review to claim a 40% prevalence of dental fluorosis This is for all forms from the most severe to the mildest. But, in fact, when the differences between “fluoridated” and “unfluoridated” areas are calculated the prevalence of all forms of dental fluorosis attributable to community water fluoridation is only 7%. And, remember, these will be only the mildest forms.

Again, very misleading.

Conclusions

The Cochrane fluoridation review agrees with all other authoritative reviews when it states:

“that water fluoridation is effective at reducing caries levels in both deciduous [primary] and permanent dentition in children.”

But its conclusions conflict with the literature on:

“the effectiveness of water fluoridation in respect of: its effectiveness in adults; its effectiveness in reducing social disparities in oral health; and the effect of cessation of water fluoridation. On these, the Cochrane Review said that there was insufficient evidence; it did not say that water fluoridation was ineffective in these regards.”

On these, the review would only say that “there is insufficient evidence.” But that is a self-fulfilling conclusion given their restrictive selection criteria. Some observers may actually say such a conclusion is irresponsible because:

“It is a fundamental premise of interpreting evidence from trials that the absence of evidence, or the existence of poor-quality evidence, should not be confused with, or taken to imply, an absence of effect. There is a risk that the Cochrane Review will be inadvertently, or deliberately, misinterpreted in this way.”

And we know this is, in fact, what has happened. Motivated anti-fluoride campaigners have chosen to present an absence of evidence (because of the restricted selection of studies) as “proof” that fluoridation is not effective.

It just shows how an “empty review” can be used to make the most unwarranted claims.

Similar articles on the Cochrane fluoridation review

Anti-fluoridationists misrepresent new dental data for New Zealand children

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Another whopper from the anti-fluoridation movement in New Zealand.

They claimed yesterday that “data released by the Ministry of Health today confirm that water fluoridation is having no noticeable effect in reducing tooth decay” (see DHB Data Show No Benefit From Water Fluoridation).

Yet a simple scan of the data (which can be downloaded from the MoH website) shows this to be patently untrue.

Here is a graphical summary of the New Zealand-wide data for 5-year-olds and year 8 children. It is for 2014 and I have separated the data ethnically as well as presenting the summary for all children (“total”).

DMFT and dmft = decayed, missing and filled teeth.

2014_5_years

214---8-yrNow – don’t these figures show the press release headline and the first sentence  are completely dishonest?

The data for all children (“total”) Maori and “other” show children in fluoridated areas have a higher percentage of caries-free teeth and a lower mean value of decayed, missing and filled teeth. The data for Pacifica are less definite – because the vast majority of Pacific children live in fluoridated areas. I discussed this further in my last post A challenge to anti-fluoridationers to justify their misrepresentation of New Zealand research.

Cherry-picking

So the headline and main message of the anti-fluoridationists press release were outright lies. However, they will fall back on the claim that the press release does contain some facts.  But these are just cherry-picked snippets taken out of context to confirm the bias of the anti-fluoride mind.

For example, comparing data for Christchurch and Nelson-Marlborough with those for  Auckland and Counties-Manukau is just disingenuous if the ethnic differences (which we know clearly play a role in oral health) are not considered. Similarly, reference to the 2o14 “overturning” of the Hamilton Council decision to stop fluoridation is just silly considering that there are no separate data for the city and the Hamilton Council fiasco over water fluoridation overlapped the period the data covers.

Of course, this press release has been processed through the international anti-fluoridation – “natural”/alternative health media channels so expect to be bombarded with international reports based on these lies.

The lesson from this little story – don’t take claims made by anti-fluoridation campaigners, or similar activists with an anti-science agenda, at face value. Always check them out.

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