Review of scientific evidence presented at landmark US federal court trial on risk of developmental neurotoxicity from artificially fluoridated water

BACKGROUND AND AIM[|]In early 2024 a US federal court judge heard testimony in a landmark lawsuit brought by citizen environmental groups against the US Environmental Protection Agency (EPA). The lawsuit is the first under the Toxic Substances Control Act (TSCA) to reach trial, potentially setting precedent for regulation of toxic chemicals. TSCA allows citizen groups to sue the EPA to compel it to classify a chemical as an unreasonable risk requiring regulation.[¤]METHOD[|]All testimony was video recorded by the court and is available online along with all evidence. I summarize and comment on the testimony and evidence presented at trial. Implications of the trial for water fluoridation policy and toxic chemical regulation are discussed.[¤]RESULTS[|]The citizen groups had testimony from five expert witnesses. Three are leading environmental epidemiologists, and members of ISEE, who have conducted original work on fluoride neurotoxicity. Another was scientific director of the National Toxicology Program (NTP) during its recent systematic review of fluoride neurotoxicity. The fifth is a risk assessment scientist involved with reviews of fluoride toxicology. The three EPA experts were a senior EPA scientist responsible for TSCA risk evaluations; a consultant environmental epidemiologist who chaired a National Academies peer-review panel of the NTP systematic review; and the lead author of a Spanish study finding an unexpected large beneficial association of fluoride with IQ. NTP has only identified adverse effects among over 70 human studies. A central focus was dose-response evidence and consistency of studies with exposures below ~1.5 mg/L water fluoride versus studies above 1.5 mg/L. The quantity and quality of human, animal, and mechanistic studies were debated, focusing on epidemiological studies.[¤]CONCLUSIONS[|]This court trial provided a unique opportunity for vigorous scientific debate on a consequential question of public health, environmental epidemiology, and the risk assessment process of regulatory agencies.[¤]