A Great Public Health Conspiracy?
The collusion of science, medicine, and the government to improve public health. Episode Five of The Reality Project.
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In January 2013, the city council of Windsor, Ontario made a curious choice. By a vote of 8–3, they implemented a plan to increase rates of tooth decay and cavities among the town’s children by more than 50%. What evil action did these councilors impose? Holding Halloween multiple times per year? Letting a candy company make school lunches? No, they did something far more disastrous: they deliberately choose to ignore mountains of medical advice, give in to public hysteria, and undo one of the greatest public health achievements of the last century, the fluoridation of public water.
Water fluoridation, adding the mineral fluoride to public water supplies to protect against tooth decay, has been a common practice since 1945. About 400 million people worldwide drink water with added fluoride, including at least 66% of the US population. Thousands of studies have found water fluoridation to be beneficial and risk-free, with the Centers for Disease Control and Prevention Concluding: “fluoride is both safe and effective in preventing and controlling dental caries” (caries being the medical term for tooth decay/cavities). Nonetheless, the government of one small Canadian town thought they knew better than the entire medical community.
After 6 years, a 51% increase in cavities among children, a 300% increase in low-income families needing financial support for dental care, and untold suffering for the town’s children, the Windsor council reluctantly reversed its decision in a December 2018 meeting. At the meeting, 5 dental experts testified, giving their full support to water fluoridation in accordance with all the medical evidence. On the other hand, 20 citizens— none with a medical degree — voiced their opposition based on unfounded fears and a belief government should not “medicate” the public even when that medication prevents children from going to the hospital. Fortunately, at the end of the day, reason, and a poll showing 80% of the citizens wanted water fluoridation prevailed, and Windsor will once again enjoy the benefits.
This story immediately caught my attention due to the intriguing elements: a great medical achievement undone by conspiracy theorists, people refusing to acknowledge a substantial body of evidence, and finally, a triumph of science over superstition. Further, it illustrates why The Reality Project, an effort to become less wrong about the world with data, is important: it’s only by examining the data that we can figure out which policies work and then — even as individual citizens — campaign for their implementation. Being right when it comes to science, medicine, and our view of the world is not just about vanity, it’s about ensuring we make the best decisions for society.
In this fifth episode of The Reality Project, we’ll dive into the evidence on public water fluoridation. While previous episodes have focused on large-scale ideas, this one is more personal: it involves your health and that of your family. We need to know the facts, because while we might initially laugh off conspiracy theorists, it’s only funny until they start eroding trust in governments, and with it, degrading the well-being of society. Perhaps we have a natural inclination to seek out insane theories (you did click on this because of “conspiracy” in the title right?) but the truth is often more amazing as is demonstrated by the data on public water fluoridation.
The Facts on Public Water Fluoridation
With any health topic, especially one that has attracted controversy, we must be careful about where we get our data. Even studies in peer-reviewed journals can have biases — intentional or not. Therefore, the best practice for reviewing medical evidence is to look at meta-analyses, reviews that evaluate results from dozens or hundreds of studies. The Cochrane Organization, a British charity, was founded to carry out systematic reviews of medical literature and make objective recommendations for the good of the public. We’ll be relying on their meta-analysis of public water fluoridation as well as one from the Australian National Health and Medical Research Council (NHMRC). For an economic analysis, we’ll use data from “Economic Evaluation of Community Water Fluoridation”.
None of these sources are captivating reading, but relying on entertainment (that is, the news) as a source of facts is disastrous when it comes to health. Reading the actual evidence is difficult, but it’s the only way to not be fooled by special interests. Wikipedia articles can be a good place to start, but we should always follow through to the citations. Here I’ll summarize the relevant parts, but if you’re skeptical, I encourage you to read the articles.
Does Public Water Fluoridation Work to Reduce Tooth Decay?
Let’s start off with an easy question: does water fluoridation work to prevent cavities and tooth decay? The unequivocal answer: yes, at least in children. According to the Cochrane review (based on 107 studies) public water fluoridation reduces cavities by 35% in baby teeth and 26% in permanent teeth. Other meta-analyses have found similar results. The report from the NHMRC found a risk reduction between 9% and 35% across studies. The same review found the number of people needed to treat (NNT) to prevent a cavity ranged from 3–14. An NNT of 3 means that for every 3 people receiving fluoridated water, 1 person will not develop a cavity as a result.
The relevant findings of the NHMRC review are pictured below. Dental caries is the scientific term for tooth decay (which is the same thing as cavities caused by acid produced by bacteria). The risk difference and the NNT are the two most helpful columns. In all studies reviewed, the risk of tooth decay was decreased by the fluoridation of public water supplies.
The Cochrane review is careful to point out there are not enough studies to confirm water fluoridation reduces the prevalence of tooth decay in adults. However, the Centers for Disease Control and Prevention (CDC) cites at least one study that showed a 20–40% reduction in cavities for adults suggesting benefits may persist throughout life. It’s important to acknowledge both the evidence we have — water fluoridation improves dental health in children — and admit where we need more research before drawing conclusions.
What are the potential side effects?
The efficacy of a medical intervention is not the only critical factor: there need to be no harmful side effects, or at least the benefits must be greater than the adverse outcomes. The second question is therefore: Are there any side effects to fluoridation? Opponents of water fluoridation list a litany of side effects (including cancer and lower IQ), but, in study after study, the medical evidence points to only one that occurs infrequently: a mild discoloration of the teeth. Known as dental fluorosis, this condition is purely aesthetic meaning it only affects how the teeth appear. In other news, drinking coffee and tea can also stain your teeth!
Any studies trumpeted by the conspiracy theorists claiming to have found negative effects examined doses far beyond what any community water fluoridation plan calls for (which is 0.7 parts per million). What this means is the only possible side effect of public water fluoridation is a slight stain similar to what you might get from too much tea. So, it comes down to what you value: if you want your teeth to rot but look impeccable, stop drinking fluoridated water (and tea)! For those of us who dislike dental pain and tooth decay, the risk of mild discoloration is well worth the benefits of fluoride.
In case you don’t believe me, perhaps the following statement from the American Dental Association (ADA) can sway you: “[the ADA] unreservedly endorses the fluoridation of community water supplies as safe, effective and necessary in preventing tooth decay”. Mind you, the ADA stands to lose from fluoridated water because of the resulting reduction in patients. Maybe the only person who benefitted from the situation? A local dentist who now has bookings through 2020 because of the cessation of water fluoridation.
Economics
An effective treatment is one thing, but the most important question for communities before implementation may be: is it worth it? We can’t put a price on the human suffering prevented, but we can look at the cost of fluoridation compared to the reduction in treatment costs for tooth decay. In the review “Economic Evaluation of Community Water Fluoridation”, 6 different studies across various population sizes were examined and the cost for water fluoridation per person per year was found to range from $0.24 to $4.85 depending on community size (larger populations mean lower per capita costs). To put these numbers in context, the average benefit provided per person per year ranged from $5.49 to $93.19.
Comparing the costs and benefits side by side, community water fluoridation delivered up to $135 for every dollar invested. In every study, the benefits exceeded the costs as can be seen in the table below:
As a note of interest, the cost to benefit ratio generally increases as the size of the community increases. This makes sense: the infrastructure is the most expensive part and the fluoride itself is relatively cheap. Therefore, the more people served from the same water system, the cheaper the costs per person.
We expect our retirement funds to deliver positive returns, and we should do the same from our public health interventions. You could do worse than put your money in public water fluoridation: it not only reduces suffering of the children in your community but can also return 135x the investment! Any community that chooses to fluoridate its water is not only improving the dental health of its citizens but doing so at a societal profit.
Alternatives
Are there other ways to get the same benefits without putting fluoride in the water? The answer is a definite yes: milk and salt can both be fluoridated and the most common alternatives are topical options including gels and toothpaste. About 90% of the toothpaste in the United States now contains fluoride. What’s more, the concentrations in toothpaste are nearly 1,000 times that of water fluoridation (1000+ ppm compared to 0.7 ppm for water)! For anyone who may be concerned with potential health effects of fluoridation, the clear solution is not to avoid tap water, but to stop brushing one’s teeth.
The prevalence of other sources of fluoride could be why the effects of public water fluoridation have decreased over the past several decades. Initial studies conducted in the 1950s and 1960s found reductions of 50–70% in tooth decay when fluoridation was introduced. However, as we learned above, the present evidence suggests a more modest reduction of around 20–35%. This is good news as the overall rate of tooth decay in the US decreases and the gaps in dental health between fluoridated and non-fluoridated communities shrinks. It should be noted however, that access to fluoridated toothpaste and alternative sources are limited in low socioeconomic areas, precisely the places where they are needed most. The CDC sums it up well:
Water fluoridation is especially beneficial for communities of low socioeconomic status. These communities have a disproportionate burden of dental caries and have less access than higher income communities to dental-care services and other sources of fluoride… Although other fluoride-containing products are available, water fluoridation remains the most equitable and cost-effective method of delivering fluoride to all members of most communities, regardless of age, educational attainment, or income level.
The best part about public water fluoridation, as opposed to the alternatives, is that it does not discriminate based on wealth. It’s also much cheaper compared to the application of fluoride gel which can cost $100 per person per year. A common refrain among opponents to public water fluoridation is that all the other options mean it is no longer needed. However, if that were the case, what can explain the rapid rise in tooth decay seen in Windsor in just a few years? Granted that is only an anecdote, but other studies have found similar adverse effects once water fluoridation is stopped. Yes, there are alternatives, but they require people to be able to afford them and know they should be using them. It’s much more effective to fluoridate public water, cover all the bases, and reach those who are most vulnerable.
Why the Pushback?
Given the above evidence: fluoride is effective, safe, and the cheapest option for preventing tooth decay especially for children, it can be hard to imagine anyone opposing this measure. Nonetheless, there is vociferous pushback to water fluoridation, often from those who oppose government intervention of any kind. The Rational Wiki has a great page that debunks many of the illogical arguments against water fluoridation, but here I’ll only mention two.
1. The World Health Organization opposes fluoridation
It is true the WHO has put out publications about removing fluoride from drinking water. However, the WHO is not talking about controlled public water fluoridation but only excessive natural fluoridation. This only applies to a very narrow section of the world population that lives in areas where the natural supply of fluoride is extremely high. Anything is dangerous in extreme amounts, including many vitamins and comparing these locations to public water fluoridation is faulty logic. The 0.7 parts per million used in the United States to fluoridate public water is well below the 4 ppm the National Resource council considers safe.
The WHO is, in fact, one of the strongest supporters of water fluoridation, unequivocally stating: “ fluoridation of water supplies, where possible, is the most effective public health measure for the prevention of dental decay.” Citing the ability of water fluoridation to reduce inequalities in health, the WHO advocates adopting this intervention wherever possible. The use of one limited example to stand in for all instances is a classic tactic used by conspiracy theorists. It represents a fallacy of over-generalization and a comparison of two entirely different situations.
2. Consumers should have a choice about water fluoridation
This is probably the most common argument against water fluoridation and comes in many forms: the government shouldn’t medicate its citizens, consumers are not given a choice to receive fluoridation, we should be able to live our lives free from tyranny. The argument from choice breaks down on several levels. Given that governments — at least in the US where the opposition is strong — are elected by the people, you do have a choice about water fluoridation. If you don’t like it, there is nothing preventing you from running for office to change things. Also, you have the choice to only drink bottled water, which may or may not be fluoridated (since the FDA is somewhat lax over enforcing regulations around bottled water).
Furthermore, children, the ones who stand to benefit most from water fluoridation, can’t vote and therefore do not have a choice either way. If things were really up to the people, then everyone would have an equal say. Also, the government does plenty of other things for public safety, like plow roads in the winter and regulate medicines. Should we have a choice about whether we want to drive on a highway covered in snow or give our children medication that could contain anything companies want (before medicine was regulated, it often killed more people than it helped). When it comes to the safety of the public, we often don’t really have a choice, which is a good thing given our predilection for irrational, harmful behavior.
The critics of water fluoridation are not numerous, they just tend to be loud. In Windsor, where 4/5 residents were for water fluoridation, a vocal minority were the ones causing most of the damage. Likewise, a 1998 Gallup Poll found that 70% of respondents in the United States were in favor of the practice indicating a small fraction of the population is responsible for the opposition. The problem appears to be not one of public opinion, but one of who is the loudest. People are much more likely to speak out when they believe (falsely) they are being hurt by the government than when they know they are being helped and it makes for more compelling news.
I’ll end this section on one telling story. When Kuopio, a Finnish city, stopped water fluoridation in 1992, they implemented the change one month before the announced cessation without telling the public. This means the public was drinking un-fluoridated water for one whole month without knowing it. Researchers used this offset to survey residents about symptoms supposedly associated with water fluoridation and even the taste of the water. The results of the research showed the residents had no clue the water fluoridation had stopped early: they reported no change in symptoms or taste of the water even after the fluoridation had been stopped.
It was only when the residents were told they were no longer drinking fluoridated water that they miraculously reported reductions in symptoms and stated they could notice a change in taste. In other words, the entire effect was in their heads. The studies’ authors nicely sum it up: “it seems likely that the prevalence of the symptoms … is connected with the psychological rather than with the physical effects of being exposed to fluoridated water.” Those who regarded fluoridation as a negative practice were most likely to report feeling better once they knew it had stopped (but noticed no change when it actually occurred). The human mind is very good at justifying irrational beliefs, and the concept that public water fluoridation is harmful has to rank as one of the most illogical theories. Whatever people’s motivation for opposing water fluoridation, one thing is clear: they have not examined the data themselves and thought critically about the evidence.
Conclusions
The story of water fluoridation is a classic tale of how medicine should work: it was intensively studied, and, after being proven safe and effective, implemented at a national scale in the United States. While the article I started with may make you question humanity’s future, I view the tale as a positive. The important lesson is that science and medicine won out in the end. Windsor is once again getting fluoridated water, and the children in the town (and potentially adults) will experience the relief. It’s worth pointing out that the truth won not by out-shouting the other side, but by presenting clear evidence. The problem is not a lack of public support for beneficial measures, it’s that the opposition is so loud. To paraphrase a famous quote, all that is necessary for superstition to win is for science to sit quietly by.
Now that you know the facts: water fluoridation clearly delivers health benefits, has no adverse side effects, and is the most cost-effective method to prevent tooth decay — you are prepared to use this information to continue making the world a better place. If humans have the tendency to seek out the sensational, then present water fluoridation as sensational. It’s a scheme carried out by science, medicine, and government on the grandest scale that has actually managed to improve public health while delivering a profit.
As always, I welcome feedback and constructive criticism. I can be reached on Twitter @koehrsen_will.
This article has been archived for your research. The original version from Towards Data Science can be found here.
