The first trial project to add fluoride to a community’s water supply began in 1945, and today, almost two-thirds of the U.S. population get their water from fluoridated supplies. Data suggest that at optimal levels, water fluoridation reduces childhood tooth decay by about 25%.
Despite findings from public health organizations and rigorous scientific studies, there have always been individuals and groups who remained skeptical of the safety of fluoride. More recently, commentary from some public figures has stoked those fears, particularly with the head of the U.S. Department of Health & Human Services publicly musing about unsupported claims of cognitive damage.
This latest study directly addresses that claim, providing clear evidence that fluoride in public water supplies has no effect whatsoever on cognitive function.
What Does The Study Show?
Proceedings of the National Academy of Sciences (PNAS) has released data from a study examining over 10,000 individuals in the graduating class of 1957.
The study measures these individuals’ intelligence levels at 6 different points in their lives. First, it collects IQ scores from tests administered by their schools in the freshman and junior years. Then, a Wechsler Adult Intelligence Scale (WAIS) was conducted at ages 53, 64, and 72. Finally, at age 80, participants were tested with the Modified Telephone Interview for Cognitive Status (TICSm).
Using address information from the 1940 and 1950 U.S. Censuses, researchers confirmed whether each participant would have been living in an area with fluoridated public water at around ages 1 and 11 years.
Then, they compared the results and concluded:
“We find no evidence that CWF is associated with lower adolescent IQ or cognition later in life.”
What Claims Is The Study Debunking?
In 2025, two states (Utah and Florida) banned community water fluoridation. Florida’s governor argued, according to the Associated Press, that people should use fluoride on their teeth, but that to have it in the water supply was “basically forced medication” and taking away individual choice.
In August of 2024, the National Toxicology Program (NTP) released findings indicating that high-concentration fluoride exposure was associated with lower IQ scores. That report noted, in bold:
What This Monograph Does Not Do:
This Monograph and Addendum do not address whether the sole exposure to fluoride added to drinking water in some countries (i.e., fluoridation, at 0.7 mg/L in the United States and Canada) is associated with a measurable effect on IQ.
Nonetheless, Fact Check reports that a then-candidate for president, who would later be named the Health Secretary, posted on social media, describing fluoride as a “neurotoxin,” quoting the report as indicating a link between fluoride and decreased intelligence, and entirely leaving out the relevant facts that this was about much higher doses of fluoride, and that the report itself was still under review.
The New Report Does Address These Claims
The researchers involved in the new study directly addressed these recent claims, noting that political figures have used them in arguments against community fluoridation.
They noted that these studies are based on exposure levels much higher than what is permitted in water supplies, and that there have been other concerns about the legitimacy and relevance of their data:
“None of their evidence came from population-representative samples; most failed to account for selection into treatment. None of the research was conducted using data collected in the United States.”
At this time, there appears to be no good data supporting claims of harm from fluoridation of community water (at regulated levels), and, in fact, this large new longitudinal study in the U.S. seems to affirm that there is none.
Why Does Community Fluoride Matter?
Yes, individuals can use fluoride at home. Infants can be given fluoride drops if recommended by their doctors, fluoride rinses and fluoridated toothpastes are available for purchase, and dentists can provide fluoride treatments.
However, community water fluoridation is a proven method to reduce tooth decay in children, to the extent that the American Dental Association (ADA) has attempted to intervene in states where bans have been passed. The ADA News released a statement when Utah passed its legislation:
“The evidence of reduced disease and cost implications provide a compelling reason to strongly consider the ramifications of ending community water fluoridation. With the weight of the evidence and nearly universal support of community water fluoridation in all corners of the health care sector, we urge your veto of [House Bill] 81,” states the letter, signed by ADA President Brett Kessler, D.D.S., and Interim Executive Director Elizabeth Shapiro, D.D.S., J.D.
Dental health is directly tied to whole-body health. Poor dental health makes it difficult to obtain necessary nutrition, causes severe pain, and can lead to further health concerns. The ADA urged legislators to choose children’s well-being over this agenda.
What Parents Can Take From All This
Conflicting studies, experts, and political figures taking opposing sides, along with heaps of data, can all be extremely confusing.
However, this latest data confirms that fluoride at levels in drinking water shows no signs of harm to children, intellectually or otherwise. Dentists, as a whole, say that fluoride is important for dental health, and recognize that dental health is vital to lifelong health.
If you do live in an area where your community water is not fluoridated, or you use water from an unfluoridated source, speak to your child’s pediatrician and/or dentist about whether you should be using fluoride drops for your infant, or if you need to take additional steps to protect your child’s teeth.
If your community water is fluoridated, rest easy. If you aren’t sure about your local water, the CDC has a page, My Water’s Fluoride, where you can get local information. For the most up-to-date and specific information, contact your local water provider.
