Fluoride is a naturally occurring mineral, and local communities across the U.S. decide whether to add fluoride to water supplies in order to reduce cavities.
The history of fluoride in water has a fascinating Colorado connection. Back in 1901, a young dental school graduate named Frederick McKay moved to Colorado Springs and while launching his dental practice, noticed brown stains on the teeth of children in Colorado Springs. McKay worked for years to understand the cause of the staining and decades later, he and other dentists and researchers confirmed that the staining was linked to naturally-occurring fluoride in Colorado Springs’ water. They also found naturally-occurring fluoride in other communities around the country. (Learn how McKay and others figured out that fluoride in water was decreasing cavities and improving dental health.)
While high levels of natural fluoride in water caused brown stains, dentists also learned that fluoride strengthened the protective coating on teeth and prevented tooth decay. That’s what led public health experts to start adding safe amounts of fluoride to water supplies. The first community to do so was Grand Rapids, Michigan in 1945. The results were stunning. After 10 years, dentists found that the rate of cavities in children in Grand Rapids dropped by 60%.
As fluoridated water has reemerged as a hotly-debated health topic, we consulted with a dental expert to answer frequently asked questions about fluoride and public health.
Dr. Bruce Dye is a professor at the University of Colorado School of Dental Medicine on the Anschutz Medical Campus. He is also chair of the Department of Community Dentistry and Population Health and is a co-author of the seminal U.S. study: “Oral Health in America.”
Dye also previously worked at National Institute of Dental and Craniofacial Research at the National Institutes of Health.
What is fluoride?
“Fluoride is a mineral that exists naturally in various concentrations in different places in the country and around the world,” Dye said.
“Fluoride is in rock and soil and there can be a lot of fluoride in water because it’s attracted to water,” he said.
Can there be too much or too little natural fluoride in water?
Yes, there can be too much. That’s what happened in Colorado Springs and in some other communities when dentists like Frederick McKay noticed some brown discoloration on people’s teeth more than a century ago.
“The natural levels in some places could be much higher than we would recommend, for instance, to prevent dental caries,” Dye said.
Some water managers dilute the amount of naturally-occurring fluoride in municipal water supplies. In other areas where there is very little naturally-occurring fluoride in water supplies, utility managers add small amounts of fluoride to water to help prevent tooth decay.
What are dental caries?
Dental caries or tooth decay is a disease process that causes tooth enamel to weaken, creating damage, tooth infection and potential pain. Dentists and public health experts more commonly use the phrase dental caries rather than talking about cavities.
Does Colorado Springs add fluoride to its water now?
No. Colorado Springs water managers dilute the amount of fluoride in the city’s water since naturally-occurring fluoride is plentiful in the Pikes Peak region. If you live in the area, you can check out an interactive map to see how much fluoride is in your water.
Do other communities in Colorado and around the U.S add fluoride to water?
Local community leaders decide whether to add fluoride to water. You can look up information about communities that add fluoride to their water through the U.S. Centers for Disease Control and Prevention (CDC).
About 63% of people in the U.S. live in communities with fluoridated water supplies.
Who decides whether to add fluoride to water supplies, and who determines safe levels?
No arm of the federal government requires communities to add fluoride to water.
“In the United States, the decision to add fluoride to a public water system is made by local communities. The federal government and the CDC don’t make that decision,” Dye said.
“The FDA (U.S. Food and Drug Administration) doesn’t regulate adding fluoride to water,” Dye said. “None of the regulatory agencies within the HHS (U.S. Department of Health and Human Services) mandate fluoride.
“So adding fluoride to water systems is voluntary, and communities, through their elected officials, make the decision about whether to add fluoride or not,” he said.
An entity called the U.S. Public Health Service has determined safe levels of fluoride in water.
What is the recommended level of fluoride in water?
Experts at the U.S. Public Health Service recommend a level of .7 milligrams per liter of fluoride in drinking water.
“The primary reason for this current recommended level is that there’s a recognition that people are also being exposed to fluoride in other ways. For example, we have widespread fluoride in toothpaste.
“So, we want to maximize the benefit for cavity prevention while minimizing dental fluorosis,” Dye said.
Fluorosis is when tooth enamel takes up too much fluoride, like an overexposure to fluoride.
“It’s mostly a cosmetic issue. In mild cases it can cause white spots or lines and in more moderate to severe cases it can cause yellowing or pitting of the teeth.”
Why do dentists and public health experts support adding fluoride in water?
“The evidence is very clear. Community fluoridation really helps children, especially those in underserved communities,” Dye said.
Fluoridated water is vital for kids who live in lower-income areas because many might not be getting regular dental care, be brushing their teeth every day with toothpaste that contains fluoride or be receiving fluoride varnishes that many children in higher-income areas receive during regular visits to the dentist.
Public health experts with the CDC echo these recommendations, noting that fluoridated water is safe and highly cost effective for the following reasons:
- Good oral health boosts overall health.
- Tooth decay is one of the most common chronic diseases among American children.
- One in four children living in poverty in the U.S. is experiencing untreated tooth decay.
- Tooth decay can reduce quality of life, increase pain for kids and negatively affect success in school.
- Tooth decay is preventable.
- Adding low levels of fluoride to water reduces tooth decay by about 25% in children.
Are there financial benefits to adding fluoride to public water supplies?
Yes. According to studies by Joan O’Connell, a health economist with the Colorado School of Public Health, communities save an average of $20 for every dollar spent on water fluoridation.
O’Connell also did an analysis of community water fluoridation programs in Colorado and found that each year of exposure to fluoridated water yielded an average savings of $60 per person.
Read more from the CDC about the health and financial benefits of water fluoridation.
Why do some people believe fluoride in water is bad for you?
While fluoridated water has been studied for decades and the scientific evidence clearly shows benefits for dental health, some people believe fluoride is harmful.
The amount of fluoride in water is key.
Researchers have studied how exposure to high levels of fluoride — more than double the recommended levels for drinking water — may decrease IQ in children.
But Dye points out that studies linking fluoride to adverse impacts on brain development are based on studies of exposure to even much higher levels.
“The issues around neurotoxicity relate to animal models, and when the animal model research was being done, mice were being exposed to very high levels of fluoride that far exceeded the public health guidelines,” he said.
Another important public health activity similar to adding fluoride to water to prevent cavities is adding folic acid to grain products to help prevent birth defects.
Does bottled water have fluoride in it?
It depends on the source of the bottled water. Some bottled water companies use springs that might or might not have naturally-occurring fluoride. Other companies use tap water that might be fluoridated.
Are communities considering taking fluoride out of their water?
Dye encourages people to review the evidence and pay attention to details. Some communities and countries — including Israel — have removed fluoride in water only to see dental caries spike among children there.
“After Israelis removed fluoride from water in 2014, the number of caries and cavities in children began to rise — which is what we would expect to happen.
“If communities stop adding fluoride to water, we should expect the same thing will happen here in the U.S.,” Dye said. “More young children will have more tooth decay requiring more trips to the dentist to address it.”
The harms likely will be greatest for the lowest-income children.
“Young children who don’t live in households where their parents reinforce good brushing with fluoridated toothpaste, their teeth may get exposed to very little fluoride.”
Why do children benefit from exposure to fluoride?
“When you’re young, and your adult teeth are beginning to develop and come in, fluoride can provide protection,” Dye said. “Having adequate fluoride at a young age strengthens the teeth and helps people throughout the course of their lives.”
People who receive plenty of fluoride as children are much less likely to develop caries and lose their teeth from tooth decay as they age.
The opposite is true too. People who don’t get enough fluoride early in life are at greater risk for dental health problems both as children and later in life.
“It’s a cycle that can repeat over your life. If you get a cavity in one of your newer adult molars when you’re 8 or 9 years old, you’ll need to get that filled. Then as you age you can remain at risk for recurrent exposure to caries and may need new fillings. Every time you get a filling, it can get bigger, and pretty soon, you might need a cap or a crown.
“If you can’t afford dental care, as the cavities get bigger and bigger, before long, the only way to solve the problem and to reduce the pain is to have teeth taken out,” Dye said. “Obviously, we don’t want children or adults to lose their teeth.
“It’s best to hold on to as many teeth as possible as you age,” Dye said. “It’s really important for supporting quality of life and well-being.”
Losing teeth has surprisingly significant impacts. Along with causing shame, pain and trouble eating, poor dental health and loss of teeth also can affect cognition for older adults.
How does fluoridation of water relate to military readiness?
Long before fluoride was ever added to water, U.S. leaders struggled to find enough young men who could serve in the military due to poor dental health.
Former President Harry Truman in 1948 created a federal entity then called the National Institute for Dental Research, now known as the National Institute of Dental and Craniofacial Research.
“The primary purpose of the Dental Institute was to find ways to reduce the prevalence and severity of tooth decay in Americans because something like one in five young men who were drafted to serve in World War II could not. The problems with their teeth were so severe that they could not meet qualification standards to enlist,” Dye said.
“In the 1940s and going into the 1950s, when we were moving into the Cold War, having so many young men with significant dental problems became a national security issue. If it would ever be necessary to fight a third World War, there would not be enough eligible men to serve without a very costly investment by the government to provide the necessary dental treatment to accept men for service,” Dye said.
So federal officials invested in research on how to improve dental health for military readiness and also to boost everyone’s overall health.
Decades ago, it also used to be common for older people to lose many if not all of their teeth.
“It used to be very common for people to have grandparents who had no teeth. They had full plates or full dentures,” Dye said. “It was very common — and even expected — that by the time people turned 30, most of their teeth might be gone from caries.”
For instance, in the 1960s, half of everyone age 65-74 had no teeth.
When fluoride started being added to water, dental health improved dramatically.
Today, among adults who are 65 or older, only about 10% no longer have teeth, Dye said.
“A big reason for that is that so many of them were exposed to water fluoridation and fluoride in toothpaste when they were young,” he said. “Fluoride has helped millions of Americans, especially older Americans, keep more teeth, and that’s fantastic.”
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