Why Fluoride Is Necessary for Public Health
The fluoride in our water protects our dental health.
The fluoride in our water has passively protected the oral health of Americans for decades by reducing cavities, tooth decay, and oral health disparities. So much so, that the CDC has declared community water fluoridation one of the 20th century's greatest public health achievements.
But recently, concerns about the safety of fluoride—a naturally occurring mineral in soil, water, and rocks—have returned to the headlines, as President-elect Trump has tapped Robert F. Kennedy Jr. as the next U.S. Health Secretary. Among Kennedy’s proposed priorities? Taking fluoride out of the drinking water.
In this Q&A, adapted from the November 22 episode of Public Health On Call, Stephanie Desmon speaks with Charlotte Lewis, MD, a pediatrician at Seattle Children’s hospital and a professor at University of Washington Medicine, about the history of fluoride in the U.S, how it protects our dental and overall health, and why it remains crucial to public health.
Why is there fluoride in the U.S. water supply? What are the benefits?
In the first part of the 20th century, dental caries [dental decay and cavities] were very prevalent, costly conditions that caused a lot of suffering, and impacted the entire population. There was a lot of tooth loss in children, and there were toothaches and abscesses related to extensive dental decay. The problems left many Americans with no teeth at all.
Around the 1930s, researchers were looking at why there were some individuals in certain parts of our country that didn't have as much dental decay, and who also had some mottling or staining to their teeth. Ultimately, they found that in some parts of the country, like Colorado, fluoride was naturally present in the drinking water.
At very high levels of fluoride intake, you can get some erosion of tooth enamel, which predisposes them to staining from things like drinking coffee. That is what these researchers were seeing. But they noticed at slightly lower levels of fluoride, you saw primarily caries prevention. That was a transformative revelation to the oral health of our country, because based on that research, they looked at other cities around the U.S. with fluoride naturally present in the water. Those concentrations varied from zero to more than four parts per million. Our current recommended amount of fluoride in community water fluoridation is 0.7 parts per million.
There were people already benefiting from fluoride in the water even before we had community water fluoridation, and researchers said, where is that sweet spot where we can optimize dental decay prevention but not cause side effects?
The reason why we know that fluoride is effective is because it's naturally present in the water around our globe, and there are more than 50 million people who are already drinking water that is one part per million, because that's naturally present in their water. This is not something that is added or a pollutant.
Does fluoridated water have side effects?
The biggest side effect that people were concerned about in the past was dental fluorosis, which is dose dependent. At low doses, it may just cause little white specks on the teeth, but those teeth are also more resistant to dental decay. As you get to higher doses, then you can start to have more adverse effects. And in some parts of the world where there are very high levels of fluoride in the environment, you actually have a chronic condition that develops called skeletal fluorosis, which is essentially very brittle bones. We don't see that sort of fluorosis in the U.S.
What do you think about the suggestion that we should remove fluoride from our water?
Trying to connect fluoride in the water to health risks has been going on for decades. Those potential connections, for example, hip fractures or bone cancer, have all been disproven through robust research.
The more recent concerns that have arisen, are about the impact on neurocognitive development based on fetal and early childhood exposure to fluoride. We don't know what the exact dose is that would cause those problems. We know that in environments, such as India, China, and Iran, where there's very high concentrations of fluoride naturally present in the soil, that there can be an increased risk of a neurocognitive effect of very high exposure [to] fluoride—but the quality of the studies is poor. Based on that, concerns then spread to lower levels of fluoride exposure, including what we use for community water fluoridation.
When did these concerns start to become more widespread?
There was an article published late in the 2010s by Rivka Green, who conducted some epidemiologic analysis based on some cities in Canada, and concluded that a fluoride exposure early in development could decrease IQ in boys. That paper was published in a prominent pediatric journal and got a lot of press.
However, there are a lot of problems with that particular study, and subsequent studies have not shown that same effect, and in fact, have shown an opposite effect. There have also been population-based studies, which do a much better job at establishing cause and effect, that have shown absolutely no effect on neurocognitive development or IQ scores, and have shown that in an economic analysis, if you have fewer cavities, you're more likely to be successful in life and to attain higher earnings in adulthood. There's even been some work showing that it's quite beneficial to have exposure to fluoride in the levels that we see in community water fluoridation. But those haven't gotten the same attention.
Unfortunately, what did get a lot of attention was a report by the [federal] National Toxicology Program, which is also a problematic document. Two attempts underwent peer review by the National Academies of Sciences, Engineering, and Medicine (NASEM) and were rejected as bad science that relied on studies of poor quality, and drew conclusions that were not supported by the research. On their third attempt, they did not take it to NASEM, and instead it went to a judge in San Francisco. Even though the report explicitly said that it was not meant to apply to community water fluoridation, or to apply to levels below 1.5 parts per million, the judge drew conclusions from it that fluoride in the water is risky to health. That is not a valid conclusion from the work.
Since we have access to fluoridated toothpaste and dental care, do we need fluoride in the water anymore?
There's a number of advantages to community water fluoridation, including that it's a relatively passive public health intervention. By adding it to the water supply, it's available to everyone, regardless of their access to dental care or their ability to routinely participate in home oral hygiene practices. That’s why we've seen it be so effective, particularly in eradicating some disparities in oral health, which are pronounced in the U.S.
If you don't consider the historical perspective, you may be led to believe that these things are no longer problems. However, you'd be ignoring the fact that we already have a very robust system in place to try to keep those issues as low as possible. Two-thirds of the population is supplied by a public water supply that has fluoride in it. Many manufacturing plants produce beverages—like juices and soda—using community water that has fluoride in it. These things are now unlabeled sources of community water fluoridation, and have diffused from centers where there's community water fluoridation into areas where it's unfluoridated.
Because of that, we've seen a smaller difference between communities with and without community water fluoridation in terms of cavity levels. In the initial studies done in the 1940s, there was a 60% drop over a period of a few years in terms of the amount of cavities in children. That's still very valid and important research, because during those studies, there were no other sources of fluoride—no supplementation. It wasn't diffusing into other communities and fluoridated toothpaste wasn't commercially available till the early 1960s. Those studies show the dramatic effect of fluoride in the water and the drop in cavities was an incredible achievement.
It may seem like we don't need fluoride anymore, but in reality, it's everywhere. Removing it from the water will cause a lot of vulnerable populations to suffer—it's not a good thing for us to be contemplating, a. And we've seen that in some studies. Calgary discontinued their fluoridation program in 2011 and over a relatively short period of time, saw dramatic increases in cavities in kids. The number of kids who are requiring IV antibiotics or needing operative dental care under general anesthesia, increased quickly with removal of fluoride from the water.
I believe ongoing use of community water fluoridation is safe because it's at a low enough level that we know that it's advantageous to be drinking it based on the research that we have.
This interview was edited for length and clarity by Morgan Coulson, an editorial associate in the Office of External Affairs at the Johns Hopkins Bloomberg School of Public Health.
