US Court Case – Frequently Asked Questions

Q. What was the lawsuit about?
A. A group of non-profit environmental and health organizations and individuals petitioned the EPA in 2016 to end the addition of fluoridation chemicals into drinking water based on the risk of neurotoxicity (brain damage). The EPA rejected the petition. In response, the citizen groups sued the EPA in 2017. The case was held in federal court in the Northern District of California in San Francisco. Judge Edward Chen heard the case and ruled in favor of the citizen groups.
https://www.courtlistener.com/docket/6201332/445/food-water-watch-inc-v-environmental-protection-agency/

Q. What health risks were brought up?
A. The court’s 80-page decision evaluated and weighed the evidence from dozens of studies on IQ loss, including studies that both sides agreed were high-quality. The court described this research as “. . . a robust body of evidence finding a statistically significant adverse association between fluoride and IQ.” This evidence included several high-quality studies from North America finding reduced IQ among children exposed to so-called “optimal” amounts of fluoride in the womb
and early infancy.

Q. Does the court’s decision apply to sources of fluoride other than community water fluoridation, such as fluoridated toothpaste?
A. No, the decision applies only to water fluoridation at the current recommended concentration of 0.7 mg/L.

Q. Did the lawsuit address possible dental benefits of fluoridation?
A. No, only possible harm. However, a CDC representative acknowledged in a sworn deposition that fluoridated water provides no cavity-preventive benefit from prenatal or infant exposure before teeth have erupted. These are the life stages when the risk of neurotoxicity is greatest.

Q. What was the court’s ruling?
A. On Sept. 24, 2024, the court ruled in favor of the citizen groups against the EPA: “the Court finds that fluoridation of water at 0.7 milligrams per liter (“mg/L”) – the level presently considered “optimal” in the United States – poses an unreasonable risk of reduced IQ in children….”

The decision also ordered the EPA to establish rules that would remedy this risk.

Q. Did the court say there was absolute certainty that fluoridated water reduced IQ?
A. Certainty of harm is not a requirement for the EPA to find an unreasonable risk, and the court did not go so far as to say there is a certainty of IQ loss from fluoridation. The court did conclude, however, that “There is significant certainty (emphasis in original) . . . regarding the association between fluoride and reduced IQ” and that “Plaintiffs have proven, by a preponderance of evidence,” that water fluoridation presents an “unreasonable risk” of this hazard.

Q. How many IQ point losses were identified by the scientific data in the lawsuit?
A. For mothers drinking an average amount of water, the expected IQ loss for their children is in the range of 1-3 IQ points. However, for mothers drinking substantially more (about 5% of the population), the estimated loss is in the range of 5-7 IQ points. Since there is a wide range of susceptibility between individuals to any toxic chemical, some children will have less (or no) IQ loss while others will have higher IQ loss than average. The court noted that a loss of just 1 IQ point “has been shown to be associated with reduced educational attainment, employment status, productivity, and earned wages….”

Q. How did the judge make his decision?
A. His 80-page ruling was based solely on the science and the TSCA statute. He considered testimony from scientists and government officials from both sides, including experts in neurotoxicity, epidemiology, and risk assessment. The judge also cited the systematic review produced by the National Toxicology Program (NTP), regarded as one of the world’s pre-eminent authorities on the hazards of chemicals. Both sides in the lawsuit agreed the NTP review was
thorough and high quality. It underwent an unprecedented degree of peer-review from independent panels of scientists. Over seven years, NTP analyzed over 70 studies on fluoride and IQ loss. Its monograph documented that out of the 19 highest-quality studies, 18 linked higher fluoride with lower IQs, several at levels in fluoridated water.
https://ntp.niehs.nih.gov/sites/default/files/2024-08/fluoride_final_508.pdf

Q. Didn’t NTP say that fluoride is consistently linked to IQ loss only at water concentrations of 1.5 mg/L and above, with lower levels not as well established? This is double the standard fluoridation level of 0.7 mg/L.
A. Yes, that’s accurate, although NTP cited several studies, all funded by the National Institutes of Health, finding IQ loss at 0.7 mg/L. Furthermore, water concentration is only one factor determining harm from fluoride intake. Another is age. The other is the dose – many people drink more water than average. They also ingest even more fluoride from food and drinks
processed with fluoridated water. All can add to its neurotoxic harms. Also, the judge cited the EPA’s standard risk assessment protocol that requires protecting those people with greater
susceptibility. To do this, the EPA takes an established level of harm and divides by at least 10 to set a level of safety for everyone in a population. Thus, 1.5 mg/L ÷ 10 = 0.15 mg/L, substantially lower than fluoridated water’s 0.7 mg/L.

Q. What did the judge require the EPA to do?
A. The judge said the EPA must take action, implementing rules to eliminate this risk of IQ loss. He did not specify what those rules should be. However, he did say “One thing the EPA cannot do . . . is to ignore that risk.”

Q. Does the ruling apply only to northern California?
A. No, it applies to the entire country.

Q. The EPA filed a notice that it would appeal this ruling on July 18, 2025. What happened?
A. The appeal went to a three-judge panel in the Ninth Circuit Court of Appeals. On May 21, 2026 it vacated (set aside) the district court ruling and sent it back to Judge Chen for another decision based only on scientific evidence up to 2020. The Court of Appeals ruled he did not have the authority to consider scientific evidence after that.

Q. Did the Court of Appeals dispute the scientific evidence establishing the higher risk of IQ loss?
A. No, neither the EPA, in its appeal, nor the Court of Appeals, addressed the science. The ruling was based solely on legal procedural issues.

Q. What happens next and how long will it take to resolve these legal issues?
A. Plaintiffs have a number of legal options they are considering, which also may be challenged by the EPA. The final resolution of these technicalities could easily take several years.

Q. Do communities have to wait for the resolution of these legal issues to take any action?
A. No, not at all. Communities or water authorities can take action to stop, or not start, fluoridation at any time. Following the original district court ruling, over 90 communities have already stopped or paused fluoridation, as have Utah and Florida. States that mandate fluoridation don’t have to wait to rescind those mandates. This FAQ produced by the Fluoride Action Network (www.fluoridealert.org), in consultation with Michael Connett, lead attorney for the plaintiffs in the lawsuit. (June 2026)