With fluoride in the political spotlight, an expert digs into the history and latest science.
In 1999, fluoridated drinking water was named one of the 10 great public health achievements of the 20th century by the Centers for Disease Control and Prevention—alongside the ability to control infectious diseases and the discovery of tobacco as a health hazard.
So why is this public health hero suddenly under growing scrutiny by politicians, citizens, and scientists?
New research—and a new administration in Washington, DC—have led many to reexamine the role of fluoride in our water systems. Despite some calls to remove fluoride from drinking water, most dentists continue to support its use, given the well-established benefits to our teeth.
“Fluoride is a naturally occurring mineral that plays a critical role in promoting dental health and preventing tooth decay,” explains Richard Valachovic, clinical professor and executive director of the Center for Oral Health Policy and Management at NYU College of Dentistry.
“It strengthens tooth enamel, helps prevent cavities, and has been a cornerstone of dental public health for decades.”
Here, Valachovic explains the backstory and newest science on fluoride, including why the dose matters:
How did fluoride end up in our water in the first place?
Fluoride is naturally found in groundwater around the world, usually in very low levels. But some areas, including parts of the western United States, East Africa, India, and China, have naturally higher levels of fluoride due to the local geology.
In the early 20th century, a dentist in Colorado discovered that fluoride in the local water was causing tooth discoloration—but it also made teeth resistant to decay. By the late 1930s, researchers determined that lower levels of fluoride would not stain teeth but still protected them against decay.
These discoveries prompted public health officials to introduce fluoride in the drinking water of Grand Rapids, Michigan in 1945, making it the first city in the world to do so. Scientists at the National Institutes of Health monitored the dental health of 30,000 Grand Rapids school children, and the results were dramatic. The rate of dental cavities among children born after fluoride was added to community water sources was more than 60% lower than that of their older peers.
This led other communities to adopt the practice and spurred businesses to develop new products to prevent tooth decay. Fluoridated toothpaste first entered the marketplace in the 1950s, and since then, toothpaste and mouth rinses containing fluoride have become widely available on supermarket and drugstore shelves.
What does research show about water fluoridation?
Decades of research and public health data consistently show that water fluoridation is an effective way to prevent tooth decay across populations, and communities with fluoridated water generally have lower rates of cavities compared to those without fluoridation.
According to the CDC, community water fluoridation safely and inexpensively reduced cavities in children by 40 to 70% and tooth loss in adults by 40 to 60 percent between 1945 and 1999.
Moreover, the cost of water fluoridation is minimal—typically less than $1 per person per year in the United States, and the return on that investment is substantial, with studies estimating that every $1 spent on water fluoridation saves about $20 to $50 in dental treatment costs. Fluoridation decreases the need for fillings, extractions, and other dental procedures, which are far more expensive than preventive measures.
That said, a lot has changed since community water fluoridation was first introduced.
With other improvements in oral health—including the availability of fluoridated toothpaste and school-based oral health programs—studies show that fluoride is no longer the silver bullet that it may have been when it was first introduced.
A Cochrane report released in the fall found that people in areas with fluoridated water had on average fewer decayed, missing, or filled teeth than those in non-fluoridated areas, but the reduction is less dramatic after the widespread introduction of fluoridated toothpastes in the mid-1970s.
Another recent analysis—published in JAMA Pediatrics earlier this month and first released last year by the National Toxicology Program—focused on fluoride and neurodevelopment. It showed a link between exposure to high levels of fluoride and lower IQ in children. It’s important to note that the fluoride levels in the studies analyzed, which were all conducted overseas, was at or above 1.5 milligrams per liter, more than double the amount in US water systems. While the research on lower levels of fluoride and neurodevelopment is more limited, recent studies out of the US and Australia show that fluoride at the levels found in US water systems is not associated with lower IQ in kids, and more research is underway.
When we take everything into account, we can conclude that current fluoride levels in US water supplies are safe, but that the dramatic impact of water fluoridation on cavity incidence and prevalence has gone down. While it’s not as effective, it’s still effective.
We should continue to evaluate emerging research and refine guidelines to ensure safety. The regulation of fluoride concentrations at 0.7 milligrams per liter—the current standard—ensures the population benefits from cavity prevention without exposure to levels associated with cognitive or neurodevelopmental risks.
So is it the amount of fluoride that matters?
Fluoride, like many other substances—even water and vitamins—is beneficial at appropriate levels but can be harmful when consumed in excessive amounts. The concerns about fluoride arise primarily from exposure to levels well above those found in regulated water supplies.
Many studies raising concerns about fluoride’s health effects come from regions with naturally high fluoride levels in groundwater where fluoride concentrations can reach 10 milligrams per liter or more. These studies provide valuable insights but are not directly applicable to communities with tightly regulated fluoride levels. In regulated systems, water fluoridation is carefully monitored to ensure levels remain within the safe range.
What do we know about cities that have stopped adding fluoride to their water?
Removing fluoride from water systems can have a measurable impact on oral health. Here in the US, Juneau, Alaska discontinued fluoride in 2007 and research revealed that cavity-related dental procedures subsequently increased by nearly 50% in children and adolescents.
In Canada, Calgary removed fluoride in 2011 and researchers subsequently found that children had more tooth decay compared to Edmonton, which maintained fluoridation. Calgary is currently in the process of reintroducing fluoride in its water. In the Canadian city of Windsor, across the river from Detroit, fluoride was removed in 2013 but the city council also voted to reintroduce it in 2018 after seeing increased rates of emergency dental care in children.
Who stands to lose the most when fluoride is taken out of community water systems?
Looking at the data, lower-income communities and children tend to be most impacted when fluoride is removed from water systems, for several interconnected reasons.
Benjamin Franklin famously wrote that “an ounce of prevention is worth a pound of cure.” Taking preventive measures to protect our teeth—through good oral hygiene, regular dentist visits, and well-regulated community water fluoridation—is far more cost effective than needing emergency dental care.
However, many people in the US face barriers to accessing preventive dental care, whether due to a lack of dentists who accept Medicaid, language barriers, or difficulty getting to appointments for those in rural areas or without reliable transportation. As a result, dental problems cause more than two million hospital emergency room visits each year in the US, with disproportionate numbers from low-income areas. Lost school and work days due to dental pain create additional financial strain, not to mention worsen the quality of life of the people experiencing them.
Without preventive measures, children are particularly vulnerable. Early childhood cavity rates are higher in non-fluoridated communities, and dental pain can affect school attendance and performance.
Given the current gaps in US dental care access and coverage, removing fluoride would likely exacerbate existing health disparities. Until there’s universal access to preventive dental care, water fluoridation remains one of the most equitable and cost-effective public health measures available.
Source: NYU
