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Editor’s note: The Defender has provided daily updates on the landmark trial pitting Fluoride Action Network against the U.S. Environmental Protection Agency since Feb. 1. The trial started on Jan. 31. To read previous coverage, click here.

A landmark trial that could determine the future of water fluoridation in the U.S. ended Tuesday with attorneys for the environmental groups and the U.S. Environmental Protection Agency (EPA) responding to the judge’s questions on technical aspects of the link between low-level fluoride exposure and lower IQ scores in children.

The two sides also debated the role of uncertainty in risk assessment.

Rather than delivering summary arguments, the attorneys responded for nearly three hours to questions from U.S. District Judge Edward Chen during the last day of the two-week bench trial in San Francisco federal court.

The trial marked the second phase of a lawsuit brought in 2017 by Food & Water Watch, the Fluoride Action Network and other environmental and consumer advocacy groups and individuals against the EPA after the agency denied their petition to end water fluoridation under the Toxic Substances Control Act (TSCA).

The trial began in 2020 but was put on hold pending the publication of the National Toxicology Program’s (NTP) report informing the case. It resumed on Jan. 31.

During the trial, top scientific experts who advised the EPA on understanding and setting hazard levels for other major environmental toxins and who conducted gold-standard “cohort” studies on the link between fluoride and low IQ in children testified for the plaintiffs.

They explained the NTP’s findings and presented evidence from their own research showing neurotoxic risks — particularly to pregnant women, formula-fed infants and children — posed by water fluoridation.

EPA witnesses conceded fluoride does have neurotoxic effects at relatively low levels, but countered that the risk assessment process under TSCA is highly complex and there is too much uncertainty in the data on fluoride’s toxicity at current levels of water fluoridation to do a proper risk assessment and regulate the chemical.

It is now up to Chen to weigh the evidence and determine if water fluoridation presents an “unreasonable risk” to human health, which would compel the EPA to create a rule regulating or banning water fluoridation in the U.S.

To do that, Chen will need to evaluate the data and set a “point of departure” — also known as the “hazard level” — the lowest point at which a toxic effect is observed or the point at which the toxin is known to cause no effect.

The hazard level he identifies would be a reference point for establishing how much fluoride the most vulnerable members of the population can safely be exposed to — which under TSCA is typically at least 10 times the hazard level, the EPA’s risk assessor told the court.

Chen also will need to determine how much fluoride exposure comes from fluoridated water — which the EPA has already established is 80%, according to EPA expert testimony in the case.

Chen’s decision could affect more than 200 million Americans who drink fluoridated water. The dental lobby and public health agencies for decades have promoted the practice as one of the 10 great achievements of the 20th century, claiming fluoridation improves dental health.

However, experts have raised concerns about fluoride’s toxicity at least since 2006, when the National Research Council published a multi-year study on fluoride’s toxic effects. And plaintiffs have been organizing for almost 10 years to get the EPA to act.

Rick North, former CEO of the American Cancer Society’s Oregon division and Fluoride Action Network board member told The Defender the lawsuit has already been groundbreaking, because it revealed that the government agencies know the risks of fluoride, despite their refusal to regulate it.

“In all the hours of testimony and all the depositions, not once did the EPA’s scientists, who were under oath, or their lawyers claim fluoridation was safe,” he said.

“On the contrary, they acknowledged there were dozens of high-quality studies linking higher fluoride with lower IQs, several at levels in fluoridated water,” he added.

“Regardless of the judge’s verdict, this alone debunks fluoridation promoters throughout the country who insist it’s been proven safe for everyone.”

EPA warns judge a ruling for plaintiffs would make the court an ‘outlier’

EPA attorney Brandon Adkins warned Chen that if he rules that water fluoridation presents an unreasonable risk and sets a point of departure, “this court would be an outlier” and “doing so at this time would be an error,” given that the public health agencies have not done so.

The EPA’s risk assessor, Stanley Barone, Ph.D., testified the “weight of the scientific evidence” didn’t support such a ruling, he said.

But Chen said, “It’s true that on whether there is an adverse effect from exposure to fluoride at low-dose levels, the evidence is mixed. We’ve got studies going both ways and a dose-response relationship is … less clear.”

“But,” he said:

“What do I do with the fact that you don’t have to go much higher to find, in the words of Dr. Barone, ‘something is going on’ and undoubtedly all the studies show that something is going on, and when you get above 1.5 [milligrams per liter (mg/L)], the studies become more consistent, almost unanimous when you are talking about higher levels.

“So even if it’s hard to find the exact point where the lowest adverse effect is observed, clearly there is an adverse effect at some level, whether it’s 2, 3, 4, 7, 10 [mg/L]. And the fact is that the community water range is not that far off in terms of multiples …

“It seems odd to say, well, we can’t identify exactly where it is. We know it’s something’s going on in this range that’s within multiples of 10 of the actual community exposure level [0.7 mg/L] in North America and the United States, but since we can’t tell exactly where it is, we’re going to not do anything.

“Is that consistent with the idea of trying to draw the inferences in favor of health and making sure that the health concerns are paramount? That’s the issue.”

Adkins reiterated that the data at low levels were mixed and contended there was too much uncertainty in the data for Chen to rule in favor of the plaintiffs.

He said it might be “an interesting thought experiment” for the court to consider estimating a conservative point of departure, such as 2 or 4 mg/L based on data presented in the trial, but that under TSCA, the EPA argued the court had to find “by a preponderance of the evidence that 0.7 mg/L fluoride presents an unreasonable risk.”

Adkins argued the court couldn’t use the 1.5 mg/L level of exposure that NTP linked to lower IQ, because such a study hadn’t previously been the basis for setting a hazard level.

He also argued that the studies that did set a point of departure, such as a study by plaintiffs’ expert witness epidemiologist Philippe Grandjean M.D. Ph.D. — adjunct professor in environmental health at Harvard and chair of environmental medicine at the University of Southern Denmark and adviser to the EPA — were “bunk.”

He implied that Grandjean had “cherry-picked” data by excluding the Spanish INMA study that found fluoride exposure increased IQ in boys — a finding even the EPA’s witnesses conceded was “implausible.”

Chen pointed out that Grandjean’s study “doesn’t really look like cherry-picking” data because it included a large study that didn’t find a statistically significant relationship between low-level fluoride exposure and lower IQ. Yet, he had identified a low hazard level of 0.28 mg/L.

Plaintiffs’ attorney Michael Connett pointed out that Grandjean’s methodology, which he had used to set hazard levels for mercury and a group of chemicals known as PFAS, was the exemplar cited by the EPA itself in its handbook on how to do such analysis.

Adkins said Grandjean’s proposed hazard level was based on urinary fluoride measures and not fluoride intake levels. Urinary fluoride levels were problematic, he said, because people could be exposed to fluoride from other sources and one couldn’t conclude the fluoride causing harm came from water.

Chen pointed out that multiple experts had testified there was a clear directional relationship between intake and urinary fluoride levels. Connett added that Barone himself said the most obvious explanation for higher urinary fluoride levels in fluoridated areas was water fluoride.

He also pointed out that two of the EPA’s own witnesses invalidated findings in and interpretations of the Spanish INMA study the EPA insisted was a key piece of evidence. The EPA’s allegation that Grandjean should have used that data, he argued, made no sense.

“Why include information which you know is false if your goal is to find the truth?” Connett asked.

‘We need to take action when we have evidence of risk’

Connett said it was important to “not let the perfect be the enemy of the good.” The EPA’s contention that there was too much uncertainty in the data to effectively do a risk assessment for fluoride “is not more important than protecting the public from a clear risk.”

He said the EPA is asserting that essentially only the gold-standard analysis called  Physiologically-based Pharmacokinetic (PBPK) modeling that would set a very precise point of departure is acceptable. But that hasn’t been necessary for other risk assessments the EPA has done.

Adkins conceded the EPA has not had PBPK models for half of the chemicals it has set hazard levels for.

Connett said the EPA was unfairly placing the responsibility for that analysis onto citizens’ groups.

“I think nowhere recognizes that maybe the EPA had a responsibility to do this a long time ago … As you may recall, the NRC told EPA in 2006 that its drinking water standards for fluoride are too high. They’re unsafe. They need to be lowered. EPA has never taken action to address that.”

He added:

“Would we all like a wonderfully exquisite PBPK model for fluoride? Yes, we all would like to see that, but that level of perfection, that level of precision, that level of certainty is not more important than protecting the American public from a clear risk.

“We do not need to wait for every piece of the puzzle to fit nicely together before we take action to prevent harm.

“And Dr. Barone’s standard of precision, perfection and certainty is antithetical to the command of TSCA to protect people before known harm occurs.

“We need to take action when we have evidence of risk, and we certainly have that here.”

The EPA highlighted the uncertainty in the data, he said, but “the uncertainty needs to be consequential.” It needs to affect whether or not a toxin would be characterized as a risk, “and I don’t see this uncertainty doing that,” he said.

“We don’t need that fine-tuned precision in order to assess risk,” he said.

Chen will now take time to assess the evidence presented and render a judgment. He did not offer a timeline for his decision, but plaintiffs estimate it will be several weeks.

At the end of the hearing, plaintiffs also asked Chen to make the video recordings of the trial available online.

Originally, the videos were scheduled to be uploaded to the District Court website as part of the Cameras in the Courtroom Pilot Program, but one of the parties contested the proposal according to court documents. Plaintiffs told The Defender they did not make the request.