John Minto’s blog article “The science is not “settled” on the benefits of fluoridation of water supplies“ is timely. For better or worse, fluoridation is in the news again and we better discuss it. John is in essence, reporting a talk by US anti-fluoride activist Paul Connett. I didn’t attend the meeting John did but the article is a good summary of the arguments Paul advanced in our recent on-line exchange (see Fluoride Debate).

I disagree with Connett’s arguments but welcome John’s summary precisely because it enables us to discuss them here. I am not really partisan on the fluoridation issue – but am partisan when it comes to science. That is my main interest in this and similar controversies (such as climate change and evolutionary science). I don’t like to see science misrepresented and distorted and that is an issue here with Paul Connett’s arguments.

Let me stress first that I admire John personally but think he is mistaken about the fluoridation issue. I am sure John will take my comments here in good faith and I hope he will be happy to discuss this issue further.

Settling in with science

First, I take issue with John’s title – because it’s along the lines of the “when are you going to stop beating your wife” question. Who exactly is claiming the science is settled? Some readers may point to Sir Peter Gluckman, the Prime Minister’s Chief Science Advisor, but they would be wrong. You can check yourself by reading his article What is in the water? where he wrote:

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“The science of fluoride in water is effectively settled. It has been one of the most thoroughly worked questions in public health science over some decades. There is a voluminous scientific and lay literature that needs to be considered.” [My emphasis]

That word “effectively” makes a world of difference. Yes, I know it is easy to miss (I did myself at first – see Poisoning the well with a caricature of science) but I think anti-fluoride activist promotion of this misinformation (the science is settled) is intentional, not accidental.

In practice scientists want to qualify every statement they make, one of the reasons they are often poor communicators. They are never totally certain. It is more about probabilities and degree of certainty – not absolute knowledge. Scientific knowledge is always provisional, subject to improvement (sometimes even change) with time and more data. That is just the way it is for a process building knowledge by relying on information from the real world.

You want absolute certainty – go see a preacher, not a scientist. But we all know that scientific knowledge, for all its incompleteness, works – and we wouldn’t be where we are today without it.

Science is never settled – but often the knowledge is good enough for governments and society to rely on for decisions and policies. Often, and on many subjects, the science is effectively settled.

We humans are used to working with that level of probability and degree of certainty. Yes, we sometimes get it wrong but we learn from our mistakes and move on. More often we get it right and make progress. In fact, if we always waited around until our knowledge was completely “settled,” until we were absolutely sure of things, we would have become extinct very early on because that is just a recipe for doing nothing. Cynical use of a precautionary principle to deny action in such cases is irresponsible. Especially when the action would reduce pain and suffering or improve our health.

There is plenty of empirical evidence for the beneficial role of fluoride in bones and teeth. Fluoridation of drinking water, salt and milk have been shown effective. The only confirmed downside so far is an increased risk of very mild dental fluorosis. The science behind fluoridation is effectively settled.

Yes, there is still plenty of scope for improving our knowledge. There are areas which are worth researching further. It is wise to also keep abreast of the changing dietary froms of fluoride intake. We know that excessive intake has negative health effects so it is important regulatory standards are maintained at appropriate levels. In New Zealand we have a body which monitors research and disseminates current findings thought the health community – the National Fluoridation Information Service. (Beware, though, of the New Zealand Fluoridation Information Service – it is an astroturf organisation set up by local anti-fluoride activists – see Anti-fluoridationist astro-turfing and media manipulation).

There is ongoing research here and elsewhere. Don’t believe anyone who suggests research on the role of fluoride has somehow stopped – it hasn’t.

Connett’s problem

John seems impressed by Paul’s presentation and arguments. I am not so impressed. My online exchange with Paul left me with the impression that he works hard in his retirement trawling the literature to find anything he can use to raise doubt about fluoridation and the effectiveness of fluoride for oral health. He starts with pre-conceived conclusions – he is acting as a political activist, not an objective scientist. (In fact, Paul has not done any original research on fluoride or fluoridation and has no credible scientific publication on the subject).

Confirmation bias is only human – we all do it. One has to work hard to overcome it but political activism doesn’t help. Paul doesn’t work in a scientific community, he is executive Director of the Fluoride Action Network (FAN). I can understand the effect on Paul of being surrounded by people whose group thinking encourages this bias – unlike a scientific community where peers routinely critically assess and comment on one’s ideas and work. It is much harder for a political activist, especially a leader, to change his or her ideas, or admit mistakes – to follow the evidence – than it is for a working scientist.

Connett’s ideological committment is wider than opposition to fluoridation. His FAN is allied with anti-vaccination and anti-GM activists through the Health Liberty Network. Similarly in New Zealand the New Health New Zealand/New Zealand Health Trust, the anti-fluoride organisation which took the High Court action to stop fluoridation in south Taranaki, also campaigns against vaccinations, genetic engineering and chemtrails (see Who is funding anti-fluoridation High Court action? ). It is basically a corporate-funded political lobbying organisation working to promote the interests of the industry selling “natural health products” and “health care products, devices, practices and services within New Zealand.” Incredibly it has charity status so we are all subsiding its activity through our taxes.

Critical and intelligent analysis required

“Skeptical scrutiny is the means, in both science and religion, by which deep thoughts can be winnowed from deep nonsense.” – Carl Sagan

It is tempting to just accept arguments from our “own side” in these sorts of debates – and most protagonists do. Confirmation bias in action. But a proper understanding of the scientific debate in these issues requires us to approach questions intelligently. Recognise the complexity of the research and published literature. Recognise the inevitable confirmation bias and cherry picking going on. We should attempt to critically consider all the available information as far as practical.

With this in mind lets look at some the arguments that impressed John.

Is fluoridation effective?

It is not ethically possible to do the ideal double blind, controlled experiment to answer that question for humans as we might with mice. So conclusions must be drawn from intelligent and critical examination of existing information. Unfortunately, cherry-pickers select data ignoring details like actual sources for fluoride intake, residential status, movement, education, alternative and new dental treatments, etc. This can be why some poeple actually believe fluoride is ineffective.

In Cherry picking fluoridation data I used the NZ data from the Ministry of Health’s database to produce the graph below . This dataset relies on dental clinic location, not the child’s residential address, to decide on fluoridation status. So it is not the ideal “experiment.”

MEAN DECAYED, MISSING AND FILLED TEETH

However, the plots clearly show fluoridation is effective but appears to decline in effectiveness in recent years – since about 2007. While some anti-fluoride activists argue that this shows fluoride is not effective the more rational explanation is that we are seeing the conversion of the school dental clinic to a “hub and spoke model“. This leads to more mixing of children from different fluoridated and unfluoridated areas.

Similarly, there is the problem of variability in the data due to low numbers and/or varaibility in dental practices. It is easy to cherry-pick the data from selected regions or years to produce figures showing fluoridation is ineffective or even that non-fluoridated children have less tooth decay! That misrepresentation by anti-fluoride activists is rife among anti-fluoridation activists in New zealand.

In todays modern world with extensive movement of individuals, multiple sources of dietary fluoride and availabilty of dental treatments it is important to analyse claims carefully. The comments by the author of a scientific paper I read recently are especially relevant:

“The preventive impact of water fluoridation is of necessity different in a place with comprehensive, widely accessible dental services, and which also enjoys the benefits of various sources of fluoride that contribute to substantial overall exposure for most children. . . . the role of water fluoridation in supporting good oral health must be weighed against other measures that may achieve similar success but at a higher cost, such as the widespread utilization of sealants. Moreover, it is unwise to resort to restorative interventions to meet the challenge of dental decay when a primary prevention measure such as water fluoridation preserves the integrity of dental tissues overall, is less expensive, and is more effective.”

Breast milk and bottle-fed infants

John has accepted Paul’s argument against fluoride based on the low concentrations in breast milk. But that is the naturalistic fallacy – “because it occurs in nature it must be right.” The fallacy becomes a bit more obvious when we consider that breast milk is also deficient in other trace elements like zinc, selenium and iron. John is quite wrong to conclude “its clear that bottle-fed babies ar being unnecessarily exposed to potential negative effects from ingesting fluoride.”

Mind you, there is room for concern by over-cautious parents. Excessive fluoride intake by babies can lead to very mild dental fluorosis. It is less of an issue than the far worse problems of tooth decay but health authorities understand parental concerns. Because there is the possibility that infants fed formula made from fluoridated water can on occasion take in an excessive amount of fluoride, health authorities advise concerned parents to use formula made up with unfluoridated water some of the time to reduce intake.

Of course, anti-fluoride activists misquote this advise to imply that formula made with flouridated water is dangerous for infants. It isn’t.

Hastings project

John should have taken Paul Connett’s story on this with a large grain of salt. Connett is being unprofessional and biased in claiming this project was fraudulent. it is a serious charge and he should know better.

Connett takes an isolated out-of-context letter to argue his case and ignores completely the published reports from the project (Ludwig and Ludwig, et al. 1958, 1959, 1962, 1963, 1965, 1971). Reasons for abandonment of Napier as a control are clearly explained in published papers (Ludwig et al (1960), Ludwig & Healy (1962) and Healy et al (1962)). In direct contrast to the claim John reports from Connett that benefits of fluoridation were not seen 8 years after the beginning of the project in 1954/1955 the 1958 paper concluded “fluoridation has produced a substantial reduction in the prevalence of dental caries in children aged six, seven and eight years.” The subsequent papers had similar conclusions.

I discussed this in more detail in my exchange with Connett and suggest John read my article for a list of these publications for him to check out for his own satisfaction. In that article I also plotted some of the data using different starting times to show any changes in dental practice at the beginning of the project did not have an over-riding influence on the conclusions.

A long-term trial involving large numbers of people, like the Hastings project, inevitably has all sorts of issues and problems. It is irresponsible to leap on an individual problem and shout “fraud.” Frankly, considering the seriousness of such a charge in the scientific community I think Connett’s behaviour is unethical.

Topical misrepresentations

Anti-fluoride activists often distort the scientific understanding of the role of fluoride in limiting tooth decay. They use current understanding of the surface mechanism involved in inhibiting the initiation of decay in existing teeth to claim ingested fluoride is useless – or even that fluoride must be applied topically to be effective! Fluoridated water and food helps support the necessary fluoride concentrations in saliva and surface biofilms supplementing the less frequent brushing with fluoridated toothpaste (see Topical confusion persists). Fluoride also helps strengthen developing teeth before eruption. Data shows that there is a beneficial effect of systemic fluoride which lasts to advanced age. The surface and systemic actions of fluoride are not exclusive but complimentary.

But let’s not forget about the beneficial role of optimum amounts of ingested fluoride to bones.

IQ studies

Paul Connett makes mountains out of the mole hills of a few poor quality studies reporting a decline in children’s IQ correlated with high concentrations of fluoride in well water. These studies ignored confounding factors like heavy metal contamination, family education, schooling and incidence of breast-feeding (known to influence IQ). Reviewers of these studies acknowledge they are not relevant to the fluoridation issue – and we all know the danger of trying to infer cause from correlation. (See figure below).

I agree with John – the reporting of such studies (these got wide attention in 2012) should be a “spur for higher quality studies to confirm/adjust/reject these findings.” He will no doubt be pleased that a very recent New Zealand study, using better data, has shown no effect of fluoridation on children’s IQ, but the expected positive effect of family education and breast-feeding.

One of Paul Connett’s “tricks” is to imply that todays researchers ignore such studies. I guess he is playing on the conspiracy theory mentality.

As for stopping fluoridation “in the meantime” to follow a “precautionary principle” – should we stop the sale of organic produce because of its observed correlation with autism – that data is far more convincing than the poor quality IQ data? Of course not. We need to approach such reports and data more intelligently and critically.

Scotland and Europe

Paul Connett is hardly original in advocating tooth brushing campaigns to fight tooth decay – we do that here to. But health authorities generally see these as complimentary to, not alternatives to, health policies like fluoridation of water, salt or milk, and dental applications involving fluoride. The Scottish ChildSmile programme that impressed John, for example, includes this target:

“At least 60% of 3 and 4 year old children in each SIMD quintile to receive at least two applications of fluoride varnish per year by March 2014.”

Connett is disingenuous to use this programme as “evidence” fluoride is not effective.

He is similarly disingenuous to quote cherry-picked studies showing no increase in tooth decay after cessation of water fluoridation as “proof” of ineffectiveness when the same studies reported substituted programmes of fluoride mouth rinses, salt and milk fluoridation and fluoride dental treatments. And, yes, most of Europe does not fluoridate it’s drinking water (for a range of reasons like high natural concentrations of fluoride, unsuitability of the water reticulation systems, etc.), but again alternative methods of fluoride delivery such as fluoridated salt and dental treatments are common.

Dispassionate look or worry-mongering?

John describes his approach, and presumably that of Connett’s as “dispassionate.” I disagree. Connett, especially, is purposely attempting to promote doubt about the science by cherry-picking and misrepresenting it. His activist organisation FAN and its New Zealand branch Fluoride Action Network of NZ (FANNZ) promotes this doubt. Many, if not most, of his supporters are ideologically driven and are often active on similar issues like anti-vaccination and anti-chemtrail campaigns. Some of them get right to what they see as the heart of the matter and rave on about Agenda 21 and the use of fluoride to keep us “sheeples” docile.

But things are never as simple as the picture presented by conspiracy theorists and ideologically motivated political activists. We should be wary about simply accepting their arguments, no matter how convincing they appear.

With subjects as complex as human health and the often contradictory appearance of the scientific literature we cannot afford to be naive. We should alway approach these claims critically and intelligently. And check them out for ourselves by considering all the available evidence.

Ken Perrott is the respected editor of very excellent open parachute on SciBlog. Sciblogs is an initiative of the Science Media Centre, an independent source of expert comment and information for journalists covering science and technology in New Zealand.