The Great Queensland Fluoridation Scare

Queensland state premier Anna Bligh announced late 2007 that Queensland would start fluoridating drinking water (at the time only done in a small fraction of the state). Predictably, anti-fluoride campaigns have sprung up.

Is this another scare along the lines of controlling tobacco or climate change will destroy the economy, or is there something in it?

I picked up a pamphlet with a number of claims, and decided to investigate them systematically. After all, if fluoridation really is bad, we ought to stop it.

I am not a dentist or involved in any way professionally or commercially with water fluoridation or dentistry. I just like to get the science straight on matters of public policy.

Here are the “facts” presented as bullet points, and investigated in like style:

• In healthy adults 50% of ingested fluoride is retained in the body. In young children 80%. (Eksterand et al. Adv Dent Res 1994b;8:175-80) – so what? These numbers are well known and are used to calculate the level of fluoridation that may be safely introduced.
  
• Too much fluoride -> poisoning – juxtaposed with the previous fact, this obvious statement (you can die from drinking too much water) is just a plain and simple scare tactic.
  
• Baby formula made up with fluoridated water is no longer considered safe (American Dental Assoc. Nov 2006) – I guess they mean this guidance published in November 2006. Nowhere does the article say they consider fluoride in drinking water in any case “unsafe”. However because of the risk of dental fluorosis (discolouring of teeth, not a dangerous condition) if very young children have too much fluoride, they recommend against mixing powdered formula (in any case not the optimum choice of baby food) with fluoridated water. Read the whole article for context. Another scare tactic.
  
• Up to 40% of the community will develop fluorosis at the fluoridation levels planned for QLD (York Review, 2000; Fluoridation of Drinking Water; A Systematic Review of Its Efficacy and Safety) – let's see what the actual review, an examination of published evidence said. At a fluoridation level of 1 part per million (ppm), the incidence of dental fluorosis could be up to 48%; that of aesthetic concern, 12.5%. This is the most negative finding reported. 12.5% with slightly off tooth colouring as a cost for reduced dental caries may be an acceptable price to pay, or not – but if we are debating based on the facts, not scares, we can be rational about this. The most important thing about the York Review is its claim that the research (positive and negative) was not of sufficiently high quality to make strong conclusions.
  
• 1% of the population displays sensitivity to fluoride in various ways e.g dermatitis, headaches, nausea and abdominal pain (Journal of Dental Medicine 16: 190-99) – they forgot to mention the year in this reference: 1961. A 1961 paper? Hasn’t the matter been studied since then? It turns out is has. The cited paper is reference [100]* in a 1990 paper, which reports a finding by a study that this and related work suffered methodological flaws (see p 9).
  
• Only 1% of fluoridated water is drunk. The rest is used in industry or domestically. Fluoridation is inefficient and costly. (Pine Rivers Shire Council, 2005) – This is a good argument for separating industrial water supply (for example to get rid of the debate about drinking recycling water). But it's a pretty weak argument in this context. If you accept the benefits, the costs are very minor by comparison. You could use the same argument against any costs in purifying the entire water supply to drinking standards.
  
• Most countries have rejected water fluoridation while Australia and USA still promote it. European countries that have ceased water fluoridation have no increase in tooth decay – no references, so I'd to look this one up. However they have a table in the pamphlet illustrating relative tooth decay rates in fluoridated and non-fluoridated areas, so let’s get back to that after the bullet points.
  
• The Australian Dental Association (ADA) aggressively promotes fluoridation but in 2006 the ADA denied any liability for any harm caused by water fluoridation – no reference, so it's hard to investigate this claim. I’m not a dentist so I’ll leave this one for the ADA to defend.
  
• Water fluoridation is mass medication denying FREEDOM OF CHOICE [pamphlet’s capitals] – this is an opinion, not a fact. Everyone’s' entitled to have an opinion of course but let’s not misrepresent an opinion as fact.
  

The pamphlet includes a table featuring areas with and without fluoridation. The rates of tooth decay in the fluoridated areas are from 0.95 to 1.38. The comparable numbers in non-fluoridated areas range from 0.76 to 1.95. All you can really say comparing two sets of numbers with such a wide range is that there must be factors other than fluoridation confounding the statistics. You need to correct for dental hygiene practices, socio-economic differences, naturally occurring fluoridation, diet and anything else that may influence the state of dental health.

What else do they have? They quote a couple of findings from the US National Research Council's 2006 report (I'm guessing they mean Fluoride in Drinking Water: A Scientific Review of EPA's Standards since they don't give a more specific reference) that ingesting fluoride causes hip fractures through increasing bone brittleness, and disrupts thyroid function. Some context is needed here: this report was motivated by complaints that the US Environment Protection Agency (EPA) had set the safety level for fluoridation at 4ppm, more than 4 times the level proposed for Queensland. The focus in the report was on deciding whether this level was too high, with a secondary focus on investigating whether 2ppm would be a safer limit. The conclusion was that 4ppm was probably too high but the risks at 2ppm needed further investigation. Presenting this data as a case against the level of fluoridation proposed for Queensland is either dishonest or incompetent.

There’s more but when I reach the point where I suspect I am being lied to, I hit the ball to the other court. Federer style.

Finally, for those who want to read further to pick up a balanced perspective, here's a good starting point: Hannu W Hausen. Fluoridation, fractures, and teeth (editorial), BMJ 2000;321:844-845.

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* Feltman, R. and Kosel, G., Prenatal and postnatal ingestion of fluorides — fourteen years of investigation — final report, J. Dent. Med., 16, 190, 1961