There is a cultural controversy dating back several decades that is very similar to the anti-vaccine controversy that we are dealing with today. Back in the early 1900s, a dentist in Colorado noticed that many of the town’s native-born people had brown-stained teeth. Not only that, but their teeth were also very resistant to decay. Through observations and testing of different water supplies in different parts of the country — where people had the brown stains and not — Dr. McKay and colleagues discovered that high levels of fluoride in water were to account for the staining and the resistance to decay. (Read more about this by clicking here.)
As it became more and more of a settled scientific concept that fluoride in water led to teeth resistant to decay (after adjusting the level to prevent the staining of the teeth), towns and cities began to add fluoride to their water supplies. Of course, not all the towns did. As is human nature, some of the people in those towns were suspicious of anything being put into their water supply by the government, beneficial or not. So not every town did.
Interestingly, this allowed for natural experiments on the effects of fluoridated water. Time after time, epidemiological studies have shown that fluoridated water leads to less tooth decay. Less tooth decay leads to better health outcomes as poor oral health is a risk factor for a variety of conditions. At the same time, all of these studies failed to see any association between bad outcomes and fluoridation done correctly.
In the modern era, where toothpaste is easily attained by most of us, the level of fluoride in potable water has been adjusted down by environmental health authorities. However, doing away with fluoridation completely would have an adverse effect on those who do not have access to toothpaste and/or dental care. Heck, I have access to toothpaste and fluoridated water, and I still managed to get cavities. Can you imagine if I didn’t?
Anyway, those people who were suspicious of putting fluoride in the water did what people who are suspicious of public health interventions often do: they heard of some bad outcome of ingesting fluoride (which is a compound made up of fluorine, the chemical element), amplified it, exaggerated it and showed it as the ultimate example of what fluoride consumption at any concentration can do to a person. If this sounds familiar to you, it’s because you’ve been reading this blog and you know the shenanigans of the anti-vaccine crowd. They took the effects of methylmercury on health, especially at high levels, then they amplified it, exaggerated it and use it as an example of what happens to everyone who gets a flu shot. Never mind that the mercury in vaccines has always been ethylmercury and at concentrations so low so as to be harmless. Never mind that saying that ethylmercury is mercury is like saying that salt is chlorine or sodium. (You don’t want pure sodium to come into contact with water, even humidity in the air. But you’ll be fine if you add salt to your broth.)
This leads us to the modern anti-fluoride movement, a group of people who are convinced that fluoride in water is, well, a sort of poisoning of the population. They are so vocal in their opposition to fluoride in the water that they actually have managed to convince some towns and cities to stop fluoridation altogether. While some scientists do push back against them, most of us don’t because we don’t see it as such a huge problem as, say, measles. We forget that not everyone can afford toothpaste, and that not everyone can afford a trip to the dentist.
Worst of all, we forget that children can and do die of tooth decay.
To make things even more complicated, some of these anti-fluoridation activists have made their way into scientific studies and publications. Like with anti-vaccine researchers and the junk studies they produce, the studies showing that fluoride causes this or that adverse event at a population level are also pretty junky.
In the next part of this short blog series, I will talk to you about a recent study from the Faculty of Health, York University, Toronto, Ontario, Canada. The study, published in the Journal of the American Medical Association, contends that increased fluoride intake by expectant mothers leads to a drop in IQ in boys. The study was so sensational that there are rumblings about removing fluoride from even more towns solely because of it. JAMA editors even had to publish an editor’s note on why they accepted the paper, and there are plenty of junk news articles that are more alarmist than informing, like this one, this one and this one. Even the American Dental Association (ADA) put out a statement asking everyone to pump the brakes on running with the conclusions of the paper.
And don’t get me started on the conspiracy sites and their take on it.
In consultation with friends and colleagues, we found a lot to be worried about in the epidemiological design of the study and the biostatistical analysis of the resulting data… And, of course, of the conclusions reached by the authors and the press (with some help from the authors). In the next part, I will lay out the epidemiological design of the study and how it is flawed both in terms of its internal and external validity. In the third part, I will lay out the biostatistical analysis issues we observed.
So, just like we had to do in the late 1990s with the Wakefield Fraud “study” that was not a study, here we go fighting a new fight against misinformation…
René F. Najera, DrPH
I'm a Doctor of Public Health, having studied at the Johns Hopkins University Bloomberg School of Public Health.
All opinions are my own and in no way represent anyone else or any of the organizations for which I work.
About History of Vaccines: I am the editor of the History of Vaccines site, a project of the College of Physicians of Philadelphia. Please read the About page on the site for more information.
About Epidemiological: I am the sole contributor to Epidemiological, my personal blog to discuss all sorts of issues. It also has an About page you should check out.