On Wednesday, the National Toxicology Program (NTP) released a long-delayed report documenting a link between elevated levels of fluoride in drinking water and lower IQ scores in children. The report marks the first time the government has acknowledged this risk, reigniting debate about the safety of fluoride, a substance that has been widely used in public health for decades.
Key findings
The report, by the NTP, an interagency program within the U.S. Department of Health and Human Services (HHS), is a comprehensive review of existing research on the potential neurotoxic effects of fluoride. It evaluated studies in a variety of geographic regions, including both areas with naturally high fluoride concentrations in groundwater and countries such as the United States, Canada, and Mexico where drinking water is intentionally fluoridated.
Key findings include:
Medium Confidence in Fluoride Neurotoxicity: The report concluded with “medium confidence” that fluoride concentrations in drinking water above 1.5 milligrams per liter (mg/L) are consistently associated with lower IQ scores in children.
Consistent evidence across studies: The report found that 18 of 19 high-quality studies reviewed showed a significant correlation between fluoride exposure and lower IQ levels in children. Additionally, the majority of studies looking at other neurodevelopmental outcomes supported these findings.
Multiple sources of fluoride: The report notes that drinking water is not the only source of fluoride exposure. Products such as toothpaste and tea also contribute to overall fluoride intake, indicating that even in areas with optimal fluoridation, total exposure may exceed recommendations.
The NTP also noted “several lines of evidence” suggesting that fluoride exposure may be associated with effects on a range of neurodevelopmental and cognitive functions in children and, to a lesser extent, adults.
The report did not assess the exact number of IQ points lost as a result of fluoride exposure.
Methodology
While mainstream media outlets such as the Associated Press have stressed that the report discusses concentrations of 0.7 milligrams per liter, double the recommended level, making the findings irrelevant, government scientists have said the exact opposite.
According to the report:
However, because people ingest fluoride from multiple sources (not just drinking water), people who live in areas with optimally fluoridated water may be exposed to higher fluoride concentrations than are present in their drinking water. Additionally, some people live in areas of the United States where natural fluoride in drinking water exceeds 1.5 mg/L.
The report's methodology was rigorous and it underwent multiple peer reviews to ensure accuracy. But the report has been criticized for softening some of its conclusions, which some believe was done to protect existing public health policies. This criticism was expressed by experts who spoke to Children's Health Defense.
Water Fluoridation in the United States
Water fluoridation has been a mainstay of public health policy in the United States since the 1940s. The initiative, which adds the natural mineral fluoride to public water supplies, was adopted as a large-scale method of preventing tooth decay. For many years, the initiative has been hailed as one of the greatest public health achievements of the 20th century, along with vaccinations and family planning.
The principle behind water fluoridation is simple: adding small amounts of fluoride to a community water supply exposes people to fluoride throughout the day, helping to prevent tooth decay. This practice has significantly reduced tooth decay, especially in children, and has earned the support of organizations such as the American Dental Association (ADA) and the World Health Organization (WHO), which considers a concentration of 1.5 milligrams per liter to be safe.
The U.S. Environmental Protection Agency (EPA) has set the fluoride standard for drinking water at 2.0 mg/L.
A study published in 2023 found that the majority of Americans are exposed to high levels of fluoride.
Despite its success in oral health, water fluoridation is not without controversy: critics argue that it is mass drugging without informed consent and that the potential risks, especially to children's neurodevelopment, have been underreported.
Fluoride Trials
The debate over the safety of fluoride has also found its way into the courts, most notably in the ongoing litigation between the EPA and the Fluoride Action Network (FAN).
In 2017, FAN, along with other advocacy groups, filed a lawsuit challenging the EPA's 2016 decision to deny a petition to regulate or ban fluoride under the Toxic Substances Control Act (TSCA). The plaintiffs argued that fluoride is a neurotoxin and should be treated like other toxic substances, including by being strictly regulated or removed entirely from public water supplies.
The case has been postponed multiple times pending the release of the NTP report. Presiding Judge Edward Cheng has paused the trial until the report is released. Now that the report has been released, the trial is likely to continue, and its outcome could have a major impact on fluoridation practices in the United States.
The EPA maintains that fluoride levels in U.S. drinking water are safe and that fluoride's benefits in preventing tooth decay far outweigh any potential risks. But the findings in the new NTP report could give plaintiffs further support and potentially lead to major changes in water treatment practices and public health policies across the country.
Delay in publication of report
Notably, the release of the report appears to have been significantly delayed due to interference from various levels of government: According to emails released in early 2023 as part of the aforementioned trial, there were multiple attempts to block or delay the release of the NTP's findings.
According to a report by the website The Last American Vagabond, internal communications revealed that NTP scientists considered their work complete in early 2022 and planned to release the report in May of that year. But HHS leadership stepped in, expressing concerns about releasing the report without further review by the National Institutes of Health (NIH) and other government agencies. This led to a series of delays, and emails show that senior officials, including the NIH director and assistant secretary of health, were involved in stalling the report's release.
The emails also note that even though the NTP was ready to release it, CDC leadership demanded additional review, effectively blocking the report. Delays were exacerbated by disagreements over whether to include certain statements in the report. Peer reviewers and government scientists debated the need to highlight that most of the studies reviewed involved fluoride exposure levels that exceeded the recommended levels for water fluoridation.
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