Appellate Court Rules in Favor of the EPA in Fluoride Matter
On May 21, 2026, the US Court of Appeals for the Ninth Circuit overturned a lower court’s ruling that would have required the Environmental Protection Agency (EPA) to issue new rules on fluoride levels in tap water.
The Opinion
In its opinion, the appellate court found that a lower court violated the principle of party presentation under which the court must act as a neutral arbiter rather than an active investigator. Among the issues cited were the lower court’s actions holding the case “in abeyance” to await publication of the NTP Monograph, State of the Science Concerning Fluoride Exposure and Neurodevelopment and Cognition and the second bench trial it subsequently held to consider that publication. The opinion described the court’s conduct as “commandeering” and concluded that it “departed so drastically from the principle of party presentation as to constitute an abuse of discretion.”
Seven+ Year Process
The original lawsuit, brought in 2017 after the EPA denied a petition to end US fluoridation, took over seven years to adjudicate. That included a four year period in which the NTP Monograph twice failed peer review by the National Academies of Science, Engineering and Medicine (NASEM), required further scientific evaluation, and underwent numerous revisions before its August 21, 2024, release. Both the report and a separately published meta-analysis have since been the subject of intense scrutiny and criticism, as have many of the studies on which they were based.
Evidence Builds
Importantly, there is ample evidence that community water fluoridation in the U.S., and as similarly practiced elsewhere, does not adversely affect neurodevelopment. Recent additions to the evidence include a November 2025 representative US study of nearly 27,000 people that examined multiple test scores across the lifespan. It found that “children exposed to recommended levels of fluoride in drinking water exhibit modestly better cognition in secondary school”. A 2025 national review in England concluded that the published evidence showed no effect on neurodevelopment or other non-dental harms. And in April of 2026, a new US study, also representative of a large population over many years, found “no evidence that [water fluoridation] is negatively associated with adolescent IQ or adult cognitive functioning.”
The Campaign for Dental Health applauds the appellate court for vacating and remanding the lower court’s ruling and providing an opportunity for the matter to be adjudicated fairly and are confident in the growing body of evidence — including over 80 years of research and more than 7,000 studies — that validates the EPA’s position.
