On January 22, the US Environmental Protection Agency (EPA) announced that it would re-evaluate its scientific review of fluoride in drinking water and potentially update the federal drinking water standards. This is a curious move from an agency that has spent the last year pausing and eliminating regulations for toxic chemicals, including rolling back drinking water protections, all actions that threaten people’s health.
A public health victory, at risk
Fluoride is a naturally occurring mineral that local governments have added to US drinking water supplies since 1945. Evidence suggests this has reduced tooth decay and cavities. It has also been helpful in closing the gap in oral health disparities, particularly among those who might not have access to reliable dental care. Nearly 63 percent of the US population receives fluoridated water. Some toothpastes contain added fluoride but it can also be naturally found in foods like black tea, oatmeal, and potatoes.
While fluoride in small amounts is beneficial for oral health, too much can lead to fluorosis, which harms our teeth and bones. In its new action, EPA points to emerging concerns regarding fluoride exposure and children’s neurodevelopment. (This is also a priority issue identified in the White House’s “MAHA” strategy.) Some recent studies, including a 2024 monograph published by the US Department of Health and Human Services’ (HHS) National Toxicology Program (NTP), have shown an association between high fluoride exposure and lower children’s IQ scores.
Local and state governments regulate drinking water fluoridation under the federal Safe Drinking Water Act (SDWA) using an EPA-set maximum level of 4.0 mg/L for fluoride in public drinking water. The EPA level was set in 1986 to prevent fluorosis, but the US Public Health Service (USPHS) suggests an “optimal level” of 0.7 mg/L for fluoridation in drinking water for dental health, which state and local governments can choose to implement. For example, my state fluoridates at the 0.7 mg/L level in accordance with the USPHS guidance. This means that state and local governments can fluoridate drinking water at lower levels, but if that level exceeds 4.0 mg/L, then the federal government will intervene.
Under the SDWA, every six years, EPA is required to review existing national primary drinking water regulations and determine whether revisions are needed. In July 2024, EPA decided not to re-evaluate the fluoride drinking water standard. In the associated technical documentation, EPA states that the agency did not consider NTP’s then-unpublished study but that, following publication, the agency would consider the results “to inform the agency’s future development of a health effects assessment for fluoride…” Then in September 2024—fueled, in part, by NTP’s study—a judge ruled in favor of a petition calling for the EPA to limit or ban the use of fluoride under the Toxic Substances Control Act (TSCA), our nation’s bedrock law for regulating toxic chemicals. The court broadly required EPA to undertake regulatory action. And then in April 2025, EPA announced, alongside HHS Secretary Robert F. Kennedy—a longtime fluoride skeptic—plans to review the science on fluoride, once again pointing to the NTP study.
As an environmental health researcher and as a parent, I believe EPA’s 40-year-old standard for fluoride in public drinking water should be reviewed and potentially updated. However, I remain puzzled by the administration’s approach, not because it is happening, but because of how it is happening.
All eggs in the NTP basket
The NTP monograph and accompanying meta-analysis, which influenced the judge’s ruling and EPA’s recent announcement, have been called into question by some experts. The monograph underwent two rounds of review by an independent committee of the National Academies of Sciences, Engineering, and Medicine (NASEM), where the committee uncovered major limitations of the study. NASEM’s second review states that while improvements were made to the first draft, the monograph contained significant issues related to potential bias in study selection and review, inconsistent review of confounding factors, and flawed statistical analysis, among other things, which can all undermine the validity of the study’s conclusions. In a letter to the NTP authors, the NASEM committee stated that while the monograph demonstrated a link between high fluoride concentrations and cognitive deficits in children, due to the aforementioned issues, “NTP […] should make it clear that the monograph cannot be used to draw any conclusions regarding low fluoride exposure concentrations, including those typically associated with drinking-water fluoridation.” Furthermore, the studies included in the meta-analysis were conducted outside the US and were from countries that have higher naturally occurring fluoride in their water supplies, which may mean that the populations studied had higher levels of exposure, making it much more difficult to make a comparison between those populations and children in the US.
When the monograph was published, it acknowledged that there were “few studies [and] uncertainty in the relationship below 1.5 mg/L when fluoride was measured only in drinking water”—levels more than twice greater than USPHS’ guidance of 0.7 mg/L. But once it was published, the nuance was lost and it spread like wildfire. Public health experts and groups like the American Dental Association have raised concerns about the weight that the NPT monograph is now being given in decision-making.
Confusion and contradiction
EPA made their announcement that they were re-evaluating fluoride and at the same time released a preliminary assessment plan for how they would evaluate the association between fluoride exposure and fluorosis and neurodevelopment outcomes. In its plan, EPA acknowledges that both the NTP monograph and a 2025 assessment by the European Food Safety Authority found adverse neurodevelopmental effects at fluoride drinking water concentrations above 1.5 mg/L, but associations at exposure levels below that are inconclusive. To put that in context, a 2023 study estimated that 2.9 million Americans, or roughly 4.5 percent of community water supplies, have fluoride concentrations equal to or greater than 1.5 mg/L.
The NTP study features heavily in the assessment plan, used as evidence for the “well-established” neurodevelopmental hazards of fluoride exposure. Yet, in a brief recently filed by EPA attorneys regarding the earlier-mentioned TSCA lawsuit, they state that the NTP study “is incomplete and not reflective of the best available science,” contradicting the agency’s own claims in this assessment. Even more, it is not yet clear whether EPA is giving equal weight to research that doesnotshow a link between fluoride exposure and cognitive effects.
These contradictions in the agency’s rhetoric related to fluoride are troubling in the broader context of the Trump administration’s ongoing attacks on science and federal scientists. While EPA’s Office of Water (OW) did conduct a risk assessment for fluoride in 2010, an assessment like this one may have historically been delegated to the Office of Research and Development (ORD), the agency’s independent science arm, which has been dismantled by this administration. Several ORD scientists were reassigned to policy offices, including the Office of Water. ORD was intentionally designed to help ensure that the agency’s science assessments could be conducted independently, without political inference. Now, that stopgap no longer exists. The agency has withheld science assessments on toxic chemicals in drinking water, rolled back drinking water limits for forever chemicals, interfered with research by OW scientists, and stopped considering the monetary public health benefits of regulation altogether.
A means to a political end
The EPA’s fluoride assessment comes at a time when Administrator Zeldin faces backlash from the MAHA movement amid the agency’s rapid deregulation of polluters and toxic chemicals. There have also been broader calls for Zeldin to resign. EPA appears to be interpreting this action under the SDWA as satisfying the judge’s ruling, rather than pursuing a review under TSCA. This is all happening as EPA is in the process of systematically weakening the TSCA process, which will allow more toxic chemicals to be deemed “safe” for use and will make it more difficult for states to ban toxic chemicals, resulting in a greater risk of increased exposures to substances like formaldehyde and asbestos. Whether this will impact states like Utah that have banned drinking water fluoridation remains unclear.
A good-faith effort to protect children’s health would start by conducting a systematic review that considers all of the best available science on neurodevelopmental impacts of fluoride. Taking the science seriously means that EPA would not rush to deregulate harmful substances such as formaldehyde, PFAS, lead, particulate matter, ethylene oxide, and so much more. The context of this re-evaluation matters. While EPA is not considering the health benefits of fluoridation in its assessment, the reality is that some fluoridation is beneficial to public health (unlike heavy metals like lead and mercury). Banning drinking water fluoridation—as HHS Secretary RFK Jr. has called for—is projected to increase tooth decay in children and health care costs for families. After 10 years of removing fluoride from its water, the city of Calgary, Canada added it back in after evidence showed that it harmed children’s dental health.
While the evidence points to a need to review the drinking water standard for fluoride to better protect the millions of Americans who may be exposed to levels higher than 1.5 mg/L, the agency must allow the OW scientists to conduct their systematic review and draw scientific conclusions without political interference. So far, the agency’s recent track record and manipulation of the scientific process under the guise of “gold standard science” doesn’t leave one with much confidence. Influencing the process so it satisfies the administration’s political goals may leave any future regulatory decision vulnerable to attacks down the line. As NASEM presciently states in its second review of the NTP monograph, “The monograph has great importance [and] will likely influence exposure guidelines or regulations. Thus, it is extremely important for it to be able to withstand scientific scrutiny by those who have vastly different opinions…”
EPA is accepting comments on its fluoride assessment plan until February 27, 2026. You can submit comments here calling on EPA to ensure scientific integrity in the systematic review process by considering all of the best available science on fluoride and neurodevelopmental effects (including those that show no association), as well as the NASEM review of the NTP monograph.