Communities across Central Florida, in recent months, have taken up the question of whether or not to fluoridate drinking water. Earlier this month, Melbourne joined a growing list of Florida jurisdictions voting to end the practice of fluoridation.
More than 70% of Floridians who get water from community water systems receive fluoridated water, , and more Central Florida communities are expected to take up the fluoride issue.
But what does it mean to fluoridate water? How long has the practice been around? And why does adding fluoride to water concern some communities?
What is fluoride?
Fluoride is a naturally occurring mineral found in groundwater, soil, rivers, and lakes, according to the National Library of Medicine.
In the United States, nearly 11% of domestic wells pump water with fluoride concentrations above the 0.7 parts per million (ppm) level currently recommended for drinking water, . One way to envision 0.7 ppm: it鈥檚 like a little less than one minute every two years, . (0.7 ppm is the same as 0.7 milligrams per liter, or 0.7 mg/L)
Cognitive impacts are associated with higher fluoride exposures starting at 1.5 ppm, a little more than twice as much as the 0.7 ppm amount recommended for drinking water, according to a review of some recent studies.
Why do we fluoridate?
Community water fluoridation is the act of adjusting fluoride amounts in drinking water to a level recommended for cavity prevention, .
Evidence shows that fluoride can prevent and even reverse early tooth decay, according to the The road to that understanding is long and when a dentist in Colorado Springs began noting brown stains on residents' teeth. However, what interested scientists was that people with brown stains were also found to be resistant to tooth decay. Decades later, researchers found that the water contained high concentrations of fluoride, which was determined to be responsible for the brown stains and the resistance to decay.
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In 1945, the first large-scale study of fluoridating water was conducted in Grand Rapids, Michigan. After 11 years of observing school children, researchers found a 60% drop in the rate of tooth decay. As a result, fluoridation projects began popping up around the country. Today, water fluoridation projects impact 200 million Americans, according to the .
Why do some people want to end community water fluoridation?
For as long as fluoridation has been going on, there have been skeptics suggesting other harmful effects of fluoride. Through the decades, water fluoridation has been heralded by a majority in the scientific community.
However, President Donald Trump's pick for Health and Human Services Secretary Robert F. Kennedy Junior is anti-fluoride and has talked about ending fluoridation, sparking renewed attention on the subject.
鈥淭hat caused a ripple effect,鈥� said Justin Harvey, a Maitland resident who says he started raising concerns to local community leaders about fluoride seven years ago. 鈥淲e've had commissioners say, solely based on that, that is good enough reason for us to take it out.鈥�
At the end of 2024, Florida Surgeon General Joseph Ladapo issued discouraging local governments from fluoridating water and going as far as to call it 鈥減ublic health malpractice.鈥� The guidance mentions a number of concerns outlined by studies, including associations between fluoride exposure and ADHD and diminished impulse control in children, as well as reduced IQ.
Those associations are identified in some from the National Institutes of Health鈥檚 National Toxicology Program: a meta-analysis, or systematic review of existing epidemiological studies on fluoride exposure鈥檚 potential cognitive impacts on children.
The new science is what a federal judge recently relied upon in favor of an anti-fluoridation coalition, which sued the Environmental Protection Agency back in 2017. Now, the EPA must reevaluate its current maximum standards for fluoride and the science behind those standards, per the ruling.
The ruling also took issue with the EPA鈥檚 current safety margin for fluoride. In its risk assessment process for chemicals, the EPA establishes a safety margin: a gap between each chemical鈥檚 maximum exposure level and hazard level, meaning the point at which known risks appear. The agency鈥檚 default safety margin is typically ten, meaning the chemical is assigned a maximum exposure level ten times lower than the hazard level.
For fluoride, though, the safety margin is only twice as high as the recommended drinking water level, 0.7 ppm. At the same time, NTP has found fluoride levels of 1.5 ppm 鈥� about twice the recommended amount of fluoride 鈥� to have some associations with negative cognitive outcomes.
The new science informing the court ruling is compelling but has some limitations. Most of the studies included in the meta-analysis were deemed low-quality (52/74), meaning they had a high risk of bias. Also, the studies didn鈥檛 all use the same methodology: some measured fluoride concentrations in drinking water, but others measured urine samples. Most of the studies reviewed were from China, and none from the United States.
That said, zooming into the handful of high-quality studies there were in NTP鈥檚 review, almost all of those studies found associations between estimated fluoride exposure in children and either reduced IQ or other types of adverse cognitive or neurodevelopmental outcomes.
Fluoride could be harmful, depending on the amount of fluoride exposure. That meta-analysis found that for every 1.0 ppm increase in urinary fluoride, there is a decrease of 1.63 IQ points in children.
What do 鈥� and don鈥檛 鈥� studies tell us about the harms of fluoride?
Much more research would be necessary to establish whether fluoridated drinking water is a primary cause of the cognitive impacts observed by some studies 鈥� especially because many other factors are already known to contribute to those cognitive impacts.
co-authored by a University of Florida researcher is the first of its kind in the U.S. to examine how prenatal fluoride exposure might impact child neurobehavior, according to Assistant Professor of Epidemiology Ashley Malin. The study鈥檚 findings are consistent with those from similar studies based in Canada and Mexico.
鈥淲e found that higher exposure to fluoride during pregnancy was associated with more neurobehavioral problems in the children by age three,鈥� Malin said.
惭补濒颈苍鈥檚 study found prenatal fluoride exposures of 1.2 ppm and above were associated with an increased risk of neurobehavioral problems, including ADHD. It did not consider IQ levels.
How much fluoride are we actually adding to water? What are we talking about here?
The Department of Health and Human Services recommends a 0.7 ppm concentration of fluoride for drinking water, which is what water utilities will typically add.
Meanwhile, for fluoride is 4.0 ppm, that鈥檚 the maximum amount allowed in public water systems. The EPA also requires systems to notify customers if average fluoride in water levels exceed 2.0 ppm.
With developments in dentistry over the years, is fluoridation still necessary?
Most dentists say yes.
Cavities are a big deal. They鈥檙e infections that lead straight to the bloodstream. show that in extreme cases, cavities can cause cardiac arrest, heart disease, or even a stroke.
鈥淔luoridated water will slow (cavities) down,鈥� said Dr. Johnny Johnson, president of the American Fluoridation Society and a pediatric dentist. 鈥淵ou will have a lot less cavities and less severe cavities. And through what you're doing, good hygiene, having fluoride in your water, using a fluoridated toothpaste, those are complementary.鈥�
Fluoridated water reduces cavities by 25% in children and adults, according to the Studies have also shown schoolchildren living in fluoridated communities have fewer decayed teeth compared to similar children in non-fluoridated communities.
According to the CDC, fluoridation is the most cost-effective way of supplying dental care across all communities regardless of age, education, and income levels.
What the new science does say:
A 鈥渟tatistically significant association between higher fluoride exposure and lower children's IQ scores, showing that the more fluoride a child is exposed to, the more likely that child's IQ will be lower than if they were not exposed,鈥� is perhaps the most compelling finding from .
The authors wrote their review finds, 鈥渨ith moderate confidence, that higher estimated fluoride exposures鈥� 鈥� specifically, at concentrations above 1.5 ppm 鈥� 鈥渁re consistently associated with lower IQ in children.鈥� (Remember, 0.7 ppm is the recommended level for drinking water in the U.S.)
What it 诲辞别蝉苍鈥檛 say:
The meta-analysis is definitive in that its findings are not definitive on fluoride鈥檚 impacts: 鈥淢ore studies are needed to fully understand the potential for lower fluoride exposure to affect children鈥檚 IQ.鈥�
And it鈥檚 key to remember, the associations found by the studies were at concentrations well above the currently recommended 0.7 ppm for drinking water in the United States. 鈥淭here were not enough data to determine if 0.7 mg/L of fluoride exposure in drinking water affected children鈥檚 IQ,鈥� according to JAMA鈥檚 meta-analysis.
Also, 鈥渢here were few studies, and therefore uncertainty, in the relationship below 1.5 mg/L when fluoride was measured only in drinking water.鈥� Remember, the studies were based in a mix of two different approaches: they measured fluoride concentrations in either urine or drinking water.
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