Fluoride Action Network

FAN Sets the Science Straight: Calgary Study Fatally Flawed

Fluoride Action Network | Bulletin | December 29, 2017

This year FAN continued to fight back against bogus science claims by fluoridation boosters. In a pattern reminiscent of the poor study methods used in early fluoridation trials of the 1940s, a new study made questionable claims that fluoridation reduces tooth decay because after fluoridation was halted in Calgary, Alberta, Canada, decay increased [Measuring the short-term impact of fluoridation cessation on dental caries in Grade 2 children using tooth surface indices, by McLaren L, Patterson S, Thawer S, et al. Community Dentistry and Oral Epidemiology, 2016 Jun;44(3):274-82].

This study was given extensive media coverage around Canada and other fluoridating countries and was used by proponents to call for Calgary to refluoridate its water (it was ended in 2011). It was also used by proponents to stymie efforts by dozens of communities elsewhere to end fluoridation.

However, a closer look showed the study omitted key data that contradicted that conclusion. When the data from an omitted dental survey was considered, there was no evidence that fluoridation cessation caused an increase in decay. Instead, it was shown that Calgary had been experiencing a steady increase in decay BEFORE fluoridation was halted, and that trend simply continued. The same trend of increasing decay was found in the control city of Edmonton which was fluoridated for the entire study period.

FAN staff collaborated with distinguished scientists to call out the study’s false claims in an article published in the same journal that published the original study [Limitations of fluoridation effectiveness studies: Lessons from Alberta, Canada, by Neurath C, Beck JS, Limeback H, Sprules WG, Connett M, Osmunson B, Davis DR. Community Dentistry and Oral Epidemiology, 2017, Dec;45(6):496-502.]

We give the details of the false science used by Lindsey McLaren below and put what happened into historical and political context of the long dishonest promotion of fluoridation since the practice began in the 1940s. But first a Fundraiser update.


Yesterday (Day 28) was another fantastic day in our efforts to raise $200,000 by midnight Dec 31.

Our total at 9 am this morning was $156,439 from 571 donors. In addition to several very large donations, we received over 100 small donations and these made all the difference to our donor total which is critically important for winning foundation support.

Thank you to all of those who went the extra mile to get their friends, family and colleagues to make small contributions of five or ten dollars. Thanks to very generous support from our super angels these numbers trigger very large pledges to us. We urge all our supporters to keep this marvelous momentum going today.

When we reach 600 donors we will receive $5,000 (that’s just 25 donors away)

When we reach 700 donors we will receive another $6,000, and yes

When we reach 800 donors we will receive another $7,000 !

To keep this simple, make one donation and then email me at pconnett@gmail.com with the names of the people (and state) who contributed to your total

How to Donate:
You can make a donation at our secure online server, or by check, payable to Fluoride Action Network.  Click here for donation details.

Before we get to the details of Calgary manipulation we should stress that there is nothing new about this tactic. Here is a Time Magazine article from April 23, 1965:
  • In 1949, Antigo, Wis. (present pop. 9,600), became one of the first communities in that state to put fluorides into its water supply in an effort to cut down tooth decay. But anti-fluoridation groups kept up a vigorous campaign, claiming that fluoride, a poison when taken in large doses, had cumulative toxic effects even when taken in small quantities. Despite doctors’ denials based on extensive surveys, worried Antigo citizens pushed through a 1960 referendum repealing fluoridation. But before fluorides were eliminated from the town’s water supply, the Wisconsin State Board of Health conducted a careful study of tooth decay among 600 of Antigo’s kindergarten and grade-school children. Antigo became, in effect, a large-scale laboratory for the testing of fluoride as a preventive of dental decay. Last fall the State Board of Health conducted another detailed study of Antigo’s schoolchildren. The results were eloquent testimony to the effectiveness of fluoridation. Four years after the repeal, cavities had increased a jarring 92% among kindergarten children, 183% among second graders, 41% among fourth graders. Convinced by the statistics of decay and by their own rising dentists’ bills, Antigo citizens voted to put fluorides back into their water supply. Last week the City Council agreed, and Antigo was back once more on the fluoridation bandwagon.

Unfortunately in 1965 there was no FAN to put a team of scientists together to show that these claims were false. This tactic has been used time and again by promoters since 1965. Now back to the Calgary study.

The Calgary manipulation

The original study was led by Lindsay McLaren of the University of Calgary. It used data from just two dental surveys in Calgary and Edmonton, one conducted long before fluoridation ceased in Calgary in 2011, and the other from about 3 years after cessation. However, she omitted a survey in Calgary held in 2009/2010 just 1.5 years before cessation. When the decay rate from this omitted survey is combined with the data used by McLaren, and displayed graphically, it is clear that decay had been increasing in Calgary at the same rate before cessation as after cessation:

Edmonton, the so-called control city because it was always fluoridated, also experienced a significant increase in decay over the study period. Therefore, instead of providing evidence that halting fluoridation caused an increase in decay, the full data show that during times when each city was fluoridated decay was increasing despite fluoridation. Factors other than fluoridation status must have been the cause of the increases in both cities. McLaren even claimed in a Canadian Broadcasting Corporation (CBC)news article that her study had ruled out alternative explanations [Lack of fluoride in Calgary drinking water leads to rise in kids’ tooth decay, study indicates, Feb 17, 2017]. Yet her study did not control for any of the confounding factors that are commonly required:  socio-economic status, diet, ethnicity, dental care, and dental hygiene practices.

This was an especially egregious example of fluoridation proponents using rigged science to support their policy. The lead author, Lindsay McLaren, was advocating for fluoridation before she began this study. Canadian public health agencies, the primary proponents of fluoridation, provided the $1 million in funding. Much of that went to McLaren’s salary over 5 years time so it is not surprising she found what her sponsors wanted her to find [McLaren curriculum vitae, May 2016]

Despite the flimsy evidence from McLaren’s study, her conclusions are trumpeted across Canada and other fluoridating countries whenever a local municipality is considering stopping an existing fluoridation scheme.

But with publication of the critique of McLaren’s study, local officials and citizens will now be able to counter the fake fluoridation science with real science. Indeed, the Calgary City Council has shown little interest in revisiting their decision to stop fluoridation.

FAN supporters made it possible to bust this bogus fluoridation science through your generosity. FAN is working on more real science projects that will help toward the goal of halting fluoridation not just in Calgary, but everywhere. More on those later.  Please contribute to keep this work going.

Paul Connett, PhD,
Senior advisor, FAN

The abstract of the critique of McLaren’s study is available here and a copy of the full article and supporting information may be obtained upon request.

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