doesn’t. The EPA doesn’t differentiate between high and low doses in determining whether something is a hazard. Barone also confirmed that once something has been confirmed as a hazard, medium- and high-quality studies are then used to identify a hazard level. These are points our attorney laid out in his opening remarks.
In what would become a defining moment in the trial, Dr. Barone testified that in his estimation we should have a margin of safety of at least 10x for fluoride to protect the most vulnerable in society. The current margin of safety between fluoridated water at 0.7 ppm and the level that NTP found neurotoxicity, 1.5 ppm, is only 2x. EPA would backpedal from this admission throughout the rest of the trial. Some observers might say this moment forced the EPA to change strategy mid-trial.
FAN attorneys then called to the witness stand Dr. Brian Berridge, DVM, DACVP, Ph.D., who oversaw the completion of the NTP’s work, to discuss the NTP fluoride review and the peer-review process.
In December 2023, EPA moved to exclude Berridge’s testimony from the trial, arguing it would speak to the political influence exerted to stop the NTP report’s publication, rather than to the scientific findings in the report, which are central to the trial. EPA attorneys argued Berridge’s testimony would be “unfairly prejudicial” to the agency. Although Berridge commented in an email, obtained by FAN via a FOIA request, that there was an ongoing attempt to modify the report to satisfy interested actors and to obstruct its publication, FAN did not call on him to speak to that issue, but rather on the integrity of the scientific process in the report’s production. In a blow to EPA, Judge Chen said he would allow Berridge’s testimony.
Dr. Berridge testified at trial that he signed off on the May 2022 version of the NTP fluoride review as a final and complete report that was ready for publication.
Read more: What Dr. Berridge Couldn’t Tell The Court
FAN Attorney Michael Connett then called veteran risk assessment scientist, Dr. Kathleen Thiessen as the next expert witness. Connett establishes that Dr. Thiessen is the author of a large portion of the 2006 NRC fluoride review, and that she also worked on the 2009 review. Connett asked Thiessen if there is any reasonable doubt that neurotoxicity is a hazard of fluoride exposure. Thiessen replied that “neurotoxicity is a hazard of fluoride exposure, the evidence is abundant”.
Connett then asked several questions comparing the NTP review process to the EPA review process, Thiessen says the EPA has not been as open and transparent. That the NTP's communication of its conclusions about fluoride's toxicity was more transparent.
Day six of the second trial in the fluoride lawsuit started off with a bang, as FAN attorneys shared with the Court a new systematic review by Canadian researchers, published the night before, linking fluoride exposure at very low levels to lower IQ in children.
Canada’s public health agency, Health Canada, commissioned a team of scientists to study the effects of fluoride on human health, but the agency did not publish the review. The peer-reviewed journal Critical Reviews in Toxicology instead independently published the study. The researchers calculated the “point of departure” for the effects of fluoride on IQ - also known as the “hazard level,” the lowest point at which a toxic effect is observed - and found it to be 0.179 milligrams per liter (mg/L) in water.
Levels of fluoride found in drinking water in the U.S. and Canada typically are in the higher range of 0.7 mg/L. The NTP report set the hazard level at 1.5 mg/L, and one of the key studies at the center of the trial set the level even lower than 0.2 mg/L.
Even at a hazard level of 1.5 mg/L, exposure levels for fluoride carry significant risk under TSCA’s guidelines, but this new level identified by Canadian researchers would set a risk level even further below current exposure levels.
The findings are important to the trial because the identified hazard level was quite low and also because the authors calculated their hazard level in terms of water fluoridation levels, which they extrapolated from the urinary fluoride levels used in most studies.
The findings also are significant because David Savitz, Ph.D., professor of epidemiology at Brown University and the EPA’s first witness, was part of the expert panel that advised Health Canada on how to interpret this study and other data. The expert panel that included Savitz concluded there wasn’t enough evidence to lower the amount of fluoride in drinking water based on its neurocognitive effects.
Next, EPA’s first key witness, David Savitz, Ph.D. took the stand. Dr. Savitz is a professor of epidemiology at Brown University School of Public Health. He worked with the National Academies of Sciences, Engineering, and Medicines (NASEM) in reviewing the draft NTP fluoride report.
Over nearly three days of testimony, Savitz downplayed the link between fluoride and IQ loss in children. Savitz’s testimony supported the EPA’s three key arguments:
Data on fluoride’s neurotoxic effects for children at current levels of water fluoridation is mixed or uncertain and therefore no action should be taken.
There are limitations to the NTP’s conclusions, published in draft form last year, linking fluoride exposure and IQ loss in children at 1.5 milligrams per liter (mg/L).
More recent studies not considered by the NTP cast doubt on the NTP’s findings.
However attorney Michael Connett and even Judge Chen pushed back on his conclusions. Connett underscored in his cross-examination that Savitz is an expert in epidemiology but has no experience researching fluoride.
Savitz testified that the Health Canada panel he was on determined that data showing IQ loss in children at existing water fluoridation levels contained too much “uncertainty” to set a hazard level for drinking water, so they advised Health Canada not to change its fluoridation levels.