By Ken Perrott 13/10/2015

I appreciate Tracey Brown, Director of Sense About Science, taking the time to respond to some of the comments in my article The ugly truth about critics of “the ugly truth” in science (see “The ugly truth” – Tracey Brown ticks me off). 

Despite apparent differences I think Tracey and I are singing from the same hymn sheet regarding the need to confront assumptions and check the evidence supporting common claims. That was the message from her lecture and I simply expanded this to include claims of the sort Tracey herself was making.

An apology

First, I must apologise for implying Tracey relied only on the reading of the two papers that were cited to me. I of course have no idea what other reading she has done on the subject – although some of her comments did reflect the views of Peckham, a well-known anti-fluoride activist, as expressed in his misleading paper Peckham (2012).

I also did not know for sure she had based her comments on “inadequate knowledge – claims from anti-fluoride campaigners she uncritically accepted.” That should have been expressed as my view, my conclusion, drawn from her lecture – rather than a statement of fact.

I did say “even scientists, and pro-science people, can suffer from confirmation bias – just like anyone else. They can sometimes adopt a partisan position which restricts them to considering only the misinformation and distortions peddled by anti-science campaigners.” However, I was simply presenting that as  a general problem – not accusing her specifically of this. We should be able to raise these possibilities without being accused of “rudeness” or “brittleness.” This oversensitivity can be an obstacle to the necessary tasks of demanding evidence for the claims being made by anyone.

The fluoridation issue

I don’t, for a minute, think Tracey has jumped on the anti-fluoride bandwagon. But I am concerned that she seems, at this stage, to have uncritically accepted some of the claims made by people like Peckham and Connett.

Tracey’s understanding of community water fluoridation (CWF) is important. A she said in her lecture, “members of the public have asked “Sense About Science” about it.” Her organisation needs to be able to correct misunderstandings and provide an objective summary of CWF. (In this respect Sense About Science is a similar position to Making Sense of Fluoride, a group I belong to). I think, at the moment, Tracey’s comments indicate her organisation’s advice on CWF could be misleading.

Tracey’s response struck me a being largely defensive – objecting to the style of some of my specific comments rather discussing the evidence for or against CWF or its handling by health authorities and decision makers. As it stands she still appears to adhere to the claims made in her lecture which, I think, are just wrong. So, it is worth expanding on some of the comments I have already made.

Is there really no critical assessment of the evidence for CWF?

It is ironic that Tracey uses CWF as an example where evidence has not been questioned. She even says that “governments went about fluoridation in the 50s by stealth, without discussion which caused a backlash.”

But the facts are that in most jurisdictions the decisions on CWF are usually made by local bodies and water companies, not governments. These decisions usually involve consultations and often very contentious debates.  Unlike many other health measures, CWF has been countered from its very beginnings by protests and representations. Although this has usually been ideologically driven and sometimes, but not always, extreme, such opposition has guaranteed a high level of discussion, consultation and scrutiny of the evidence.

That continues to the present day. In my own city (Hamilton, New Zealand) pressure from activists to cease CWF lead to a limited consultation by the council in 2013, and a decision to stop fluoridating. Citizens, many of them quite knowledgeable on the subject, reacted because they felt they had not been properly consulted or listened to and the council had ignored previous referendums and their own polling data. A new referendum showed overwhelming support and subsequently  the council reversed their decision and CWF returned to our city in 2014.

Actually, this illustrates two features which must be taken into account in our defence or criticism of social health policies.

  1. Often the central issue is one of values – even the conflict between a social approach or a libertarian one. Decision-makers should take account of such values in their community as they may be more relevant than the science.
  2. Decision-makers often just do not have the skills to judge scientific evidence. This was particularly true for the Hamilton City Council which was effectively swamped by anti-fluoride activists promoting misinformation and distortion.

For many people involved in this process, and many citizens, CWF has been revisited so many times, the evidence scrutinised and criticised so many times, there is indeed a backlash. Citizens are not happy about their local bodies spending so much time and money on repetitive consultation and even react negatively to new referenda. New Zealand local bodies now wish to unload the whole issue onto Central government arguing, quite legitimately, they do not have the expertise to make such decisions. They have had a gutsful of the issue.

Benefits of opposition

This continual consultation and rehashing of the evidence has produced some positive outcomes – the anti-fluoride activity has a silver lining. The Royal Society of NZ, together with the Office of the PM’s Chief Scientific advisor produced a review updating the evidence relevant to the efficacy and safety of CWF to the middle of 2014. The citation is:

Eason, C., & Elwood, JM. Seymour, Thomson, WM. Wilson, N. Prendergast, K. (2014). Health effects of water fluoridation: A review of the scientific evidence.

This was partly financed by local bodies who felt thoroughly confused by the competing claims. I suggest Sense About Science people read this document, and others, in their efforts to get up to speed on CWF.

Not only does NZ now have an up-to-date review of CWF we also have several High Court decisions which put to rest some of the claims made by activists. Poetic justice perhaps – as funding  from the “natural”/alternative health industry has actually produced scientific and legal judgements supporting CWF! The opposite of what they intended.

Setting “optimum” levels

Tracey said in her response:

“I stated, briefly, that the one part per million figure originates from those old studies. Other parts of the world have rejected it in favour of different concentrations. My reading of the subsequent research on concentrations was that it was not possible to come up with a clear case for one part per million, as opposed to say 0.7 as used elsewhere, and that although the need for controls is better understood and sometimes applied, the multiple and variable sources of other contributors to dental health have made it harder to get a signal from the noise. In the lecture, I pointed out that it’s very difficult to control and measure the dose that people actually get from water. It’s not clear whether you disagree with this.”

Her original comment on “old studies” still stands. As I said before, standards are set according to the studies available at the time – this does not mean they are not revisited or changes as new studies become available. This has, in fact, happened with CWF and it is misleading to imply otherwise.

I don’t think it is a matter of “rejecting” the research. Health authorities and decision makers in each country make decisions about “optimum” levels taking into account their own specific situations, dietary intake, drinking water consumption, etc. Counties don’t “reject” decisions of other countries.

Of course it is hard to control and measure the “dose”, or intake – but that is true for any beneficial element – most of which have upper and lower bounds for recommended intake. Dietary consumption is hardly an exact science – one should not be concerned about the 0.7 or 1 ppm difference. Why should fluoride present a special problem?

Personally, I see talk about “dose” as another misleading argument promoted by anti-fluoride campaigners. Firstly, because of the implication such accuracy is required and secondly because it is painting fluoride out to be in the same class as a very active and possibly toxic drug requiring accurate control – which it isn’t. Really, fluoride is in the same class as sodium, potassium, phosphorus, magnesium and selenium. It is not a drug.

Trends of declining dental decay

No one claims CWF is a magic bullet, or that it is the only factor behind improving oral health. Yet the graphic Tracey used is promoted constantly by campaigners to “prove” CWF is ineffective by implying health authorities see fluoride as the only factor involved.  The graphic “proves” nothing except that oral health has improved over the years.

In my article I assumed Tracey used the image from Cheng et al (2007). In fact, her comments on Austria introducing gobstoppers suggest she probably used the one below from Peckham (2012). There are warning signs there as the citation was a personal communication from Chris Neurath – an activist and “research director” in the management of Paul Connett’s Fluoride Action Network. Even the journal citation should ring bells as Fluoride is a poor quality journal effectively managed by the anti-fluoride community.

Peckham image

And, as I pointed out in my original article, these images avoid showing the WHO data within countries – which do show that CWF is effective. It is extremely naive, and misleading, to suggest that the WHO data shows that it is not effective.

I am seriously concerned that inadequate review of the scientific literature will lead to Sense About Science promoting this misleading graphic in its response to public requests for information.

Real world problems for public discussion of evidence

Institutional cultures often restrict the ability of staff to comment publicly. This may be expressed as a condition of employment or it may just be informal discouragement. On the fluoridation issue, it may just be a matter of institutions preventing staff from participating in the “street-fighting” nature of many of the public discussions. In fact, some local institutions have said they are not ready to expose their staff to the threats and abuse which are often part of these public discussions. It is a health and safety issue for them.

Consequently, these discussions are often handled better by non-institutional “activist” groups like Sense About Science. The group Making Sense of Fluoride (MSoF)is effectively a sister group to Sense About Science, but concentrating on the scientific and ethical issues around community water fluoridation. It was formed precisely because institutions like District Health Boards are not able to take part fully in the public debate. Many MSoF people are not limited by institutional requirements.

Incidentally, institutional restrictions are another reason many people who discuss scientific issues publicly are retired. Such retirees often have the background knowledge and research skills necessary for this discussion but no restriction on what they can say, and where.

Tactical approaches are also important. Very often the public is not interested in the scientific details and qualifications which should be attached to evidential claims. They are often happy to leave such discussion to the “boffins.” Scientific debates may be suitable for some fora but can be a real turn off in referendums. Institutional decisions to forgo scientific debate and detailed qualifications may be completely correct in such situations.

The public discussion of science, which was the subject of Tracey’s lecture, is not simple and we should not neglect the social and psychological research about public opinion and the way to communicate with the public.


I am grateful to Tracey for responding to my article and wish her and Sense About Science the best in updating their knowledge on CWF.

I am a little disappointed her response was defensive and did not involve an in-depth discussion of CWF. This is probably natural, but it is important that groups like Sense About Science and Making Sense of Fluoride not ignore such challenges. It is also important for such groups to be ready to update their knowledge and opinions on issues when required.

In her article Can you handle the truth? Some ugly facts in science and sensibility introducing her lecture Tracey said:

“The ugly truth is that all of us – however informed, however good our intentions – end up letting things slide once in a while. We overlook, overstate or understate the evidence behind research, claims, or policies, for a number of reasons.”

So true – and something we should continually come back to.

I think Tracey was guilty of this in her claims about CWF. Granted, these were only a small part of her lecture. But to anyone with sufficient knowledge to see her mistakes the claims about CWF did detract from the authenticity of the other claims she made.