Category Archives: dan savage

Fluoridation: Connett’s naive use of WHO data debunked

Paul Connett is the Executive Director of the anti-fluoride propagandists group, the Fluoridation Action Network (FAN). His recent presentation to the Denver Water Board’s fluoridation forum was full of scientific misrepresentations and distortions.

I debunked his claims on fluoridation and IQ in the article Connett misrepresents the fluoride and IQ data yet again. Here I debunk his claim that WHO data shows community water fluoridation (CWF) is not effective.

This video clip shows his claim:

1: Is there a difference between fluoridated and unfluoridated countries?

Connett waves around graphs showing declines in tooth decay in  some countries but does nothing to support his claim that there is no input from fluoridation to this improvement in oral health. After all, oral health depends on a number of factors so any serious claim needs adjustment for these factors and a proper quantitative comparison.

The data in these graphs is just not suitable for this – but lets humour people like Connett who place so much faith in the graphs. I took this graph from Connett’s book The Case against Fluoride (Chapter 6, page 38).


It is easy enough to do a ballpark comparison of the average rate of decline of dental decay  for the four nonfluoridated countries and compare that to the average rate for the four fluoridated countries. I did this and found the average decline in dmft (decayed, missing and filled teeth) for non-fluoridated countries was 1.4/decade and for fluoridated countries 1.6/decade. On the face of it the decline in tooth decay was more rapid in the fluoridated countries – the opposite to Connett’s claim.

Of course, Connett would laugh at such a comparison and claim the data is just not good enough to make such comparisons.  And I agree – but isn’t that exactly what he was trying to do?

He was simply waiving around a poor set of data which he thinks supports his claim that CWF is ineffective – it doesn’t. He should know that, and he should be ashamed, as someone with scientific training, to make these claims using such evidence.

The huge influence of inter-country differences on these data, irrespective of fluoridation, surely sticks out like a sore thumb in Connett’s graphs. That doesn’t require a scientific training to see. These differences introduce so much noise into the data that no conclusion is possible about the influence on fluoridation.

Robyn Whyman pointed this out in his report for the National Fluoridation Information Service – Does delayed tooth eruption negate the effect of water fluoridation?:

“Studies that appropriately compare the effectiveness of water fluoridation do not compare poorly controlled inter-country population samples. They generally compare age, sex, and where possible ethnicity matched groups from similar areas. Inter-country comparisons of health status, including oral health status, are notoriously difficult to interpret for cause and effect, because there are so many environmental, social and contextual differences that need to be considered.”

2: Comparison within countries

The WHO data includes New Zealand and Ireland where there are fluoridated and unfluoridated areas. Cornett’s graphs do not differentiate – the just use the averages for these two countries.  Yet, even that sparse WHO data set  shows clear benefits of community water fluoridation on oral health. Consider the differences in tooth decay between fluoridated and unfluoridated areas of  Ireland.

I showed this graph to Connett at the beginning of our debate on fluoridation. throughout the next few months he continued to confuse the issue and I kept coming back to it. Finally, he said in his closing statement, “My apologies. I should have checked back.”

An acknowledgment, of sorts, that his use of the WHO data is wrong in his graphs – but he continues to misrepresent it in this way!

The data in the graphs below shows a similar situation for New Zealand – this time using data from the NZ Ministry of Health (which is much more extensive than the WHO data).dmft

3: CWF still effective when fluoridated toothpaste used.

Paul Connett’s claim that CWF is unnecessary when fluoridated toothpaste is used was based on a naive interpretation of the graphs he was waving around. The data above for Ireland and New Zealand show that, even where the use of fluoridated toothpaste is widespread, there is still a difference in the oral health of children living in fluoridated and unfluoridated areas of a country.

Other research also shows CWF is still effective, even though its effectiveness may, these days, be less than observed in the past when fluoridated toothpaste was not used. But, in contrast to what Connett appears to think, fluoridated toothpaste in not the only factor involved. There is the general improvement in dental health treatments and diet in recent years. Rugg-Gunn & Do (2012)  also refer to the “halo” effect – a diffusion of beneficial fluoride from fluoridated area into unfluoridated areas via food and beverages and consumption of water away from the place of residence.

The recent data can also be influenced by differences in residence and place of dental treatment. For example, dental treatment and record taking may occur at a school or dental clinic in a non-fluoridated area but the child may live in a fluoridated area. This effect could explain the apparent reduction of differences for New Zealand children from fluoridated and non-fluoridated areas after 2006 in the above graph. In 2004 a “hub and spoke” dental clinics system was introduced where one school dental clinic could serve several areas – both fluoridated and non-fluoridated.



Paul Connett’s use of the graphs showing improvement in oral health in countries independent of fluoridation, is on the surface, naive because no conclusion about the effectiveness of CWF can be drawn from this sparse data involving comparison between countries with so many political, social and environmental differences. Connett is presumably aware of this, and of the fact the same WHO data shows a beneficial effect for Ireland and New Zealand.

This is another case of Connett using a scientific academic title (his PhD), to give “authority” to his misrepresentation and distortion of the science to local body politicians.


Connett, P., Beck, J., & Micklem, H. S. (2010). The Case against Fluoride: How Hazardous Waste Ended Up in Our Drinking Water and the Bad Science and Powerful Politics That Keep It There.

Ministry of Health (2014) Age 5 and Year 8 oral health data from the Community Oral Health Service.

National Fluoridation Information Service (2011): Does Delayed Tooth Eruption Negate The Effect of Water Fluoridation? National Fluoridation Information Service Advisory June 2011, Wellington, New Zealand.

Rugg-Gunn, A. J., & Do, L. (2012). Effectiveness of water fluoridation in caries prevention. Community Dentistry and Oral Epidemiology, 40, 55–64.

Attitudes will change. Life will get better

This video needs to be seen by everyone. It’s important

Fort Worth City Councilman Joel Burns reaches out to GLBT teens with a personal story and a message of hope.

Vodpod videos no longer available.

Thanks to PZ Myers: You can’t be unmoved by this video : Pharyngula.