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Editor’s note: The Defender is providing daily updates on the landmark trial that started Jan. 31 pitting Fluoride Action Network against the U.S. Environmental Protection Agency taking place in San Francisco, beginning Feb. 1. To read previous coverage, click here.

During the second day of testimony in a landmark fluoride trial, expert witnesses presented evidence that fluoride exposure is associated with lower IQ in children and that it poses risks to pregnant mothers.

Food & Water Watch, Fluoride Action Network, Moms Against Fluoridation and other advocacy groups and individuals are suing the U.S. Environmental Protection Agency (EPA), in a bid to force the agency to prohibit water fluoridation in the U.S. due to fluoride’s toxic effects on children’s developing brains.

The agency maintains that the 0.7 milligrams per liter (mg/L) recommended level at which fluoride, an industrial waste byproduct, is added to community water supplies is safe

However, in their testimonies, Dr. Bruce Lanphear, professor of Health Sciences at Simon Fraser University, and Philippe Grandjean, M.D., Ph.D., adjunct professor in environmental health at Harvard and chair of environmental medicine at the University of Southern Denmark, outlined the findings of a large body of evidence they said contradicts the EPA’s claims about safety.

Both men are experts on environmental toxins, including fluoride and lead, and have acted as advisors to the EPA and other international organizations on setting hazard levels for major environmental toxins.

Fluoride, maternal hypothyroidism and fetal health

During the first day of testimony the plaintiffs’ first expert witness provided an overview of research on the neurotoxic studies of fluoride for the developing brain from the Mexican ELEMENT, the Canadian MIREC and the Danish Odense cohort studies — where researchers collect epidemiological data during pregnancy and then from children over their lifetimes to study a variety of health outcomes tied to environmental exposures.

The EPA implied in its cross-examination of Hu that pooling data from these three cohorts to establish a benchmark dose without first publishing the Odense data was a form of selective reporting of results.

On Thursday, attorney Michael Connett, who represents the plaintiffs, asked Lanphear — who created the benchmark for acceptable levels of lead for the EPA — about pooled analyses.

Lanphear said he and his colleagues also used a pooled analysis to create the EPA’s benchmark for lead and in that work, they included previously unpublished data in that paper, which he clarified is not an uncommon practice.

In the rest of his testimony, which lasted several hours, Lanphear walked the court through evidence from his research as a principal investigator on different MIREC cohort studies.

In one study, for example, they found babies fed with formula made from fluoridated water had lower IQs as children.

The questioning then turned to the details of Lanphear’s work linking water fluoridation to hypothyroidism in pregnant mothers of children with lower IQ scores, which he said may be one of many possible mechanisms by which fluoride impacts fetal brain development.

It is undisputed in the literature that hypothyroidism in mothers causes IQ loss in children, he said, and his research investigated whether fluoridated water could cause that hypothyroidism.

Research by the National Resource Council has shown that fluoride is an endocrine disruptor, he said, which means it can disrupt the proper functioning of the thyroid gland.

That could be a possible mechanism for the effects of fluoride on IQ, he said. He also noted that in the past, fluoride was administered as a drug to treat people with hyperthyroidism.

Lanphear published this research, which was funded and had its methodology vetted by the National Institutes of Health (NIH) in several papers. His team measured fluoride in several different ways — the amount ingested, the amount in the water supply and the amount in the mothers’ urine. The researchers found a statistically significant link between fluoridated water levels and lowered children’s IQ, but not with the other measures.

On cross-examination, the EPA challenged this finding, asking whether the study accounted for the fact that pregnant mothers may have moved into the study area from other locations that were not fluoridated — only about 38% of Canada fluoridates its water — meaning their hypothyroidism could have had a different origin. Lanphear conceded the study did not account for that possibility.

After the hearing, Lamphear explained the link between fluoride and hypothyroidism among pregnant women to journalist Derrick Broze:

In his testimony, Lanphear addressed the variability of findings in different studies — some find sex-differentiated responses to fluoride and others don’t, or some find neurotoxicity at lower levels and some at higher levels.

Lanphear told the court that studies with different findings are often compatible, or demonstrate the same broader issue.

For example, he said, the same variability exists in toxicity studies for lead, where some studies find greater effects in boys and others in girls. Still, the overall indication is that lead is toxic and other factors drive sex differentiation in a particular context.

This variability, he says, brings up questions about things that ought to be investigated further.

Connett asked Lanphear whether there is reason to believe that Americans living in poor and low-income communities might be more susceptible to fluoride, which Lanphear confirmed, pointing to studies in Cincinnati and Rochester.

It is widely reported in the literature, he said, that children in poor communities are exposed to toxic chemicals at higher rates generally.

In cross-examination, the attorney for the EPA questioned the generalizability of Lanphear’s findings. He said all studies, including his, have limitations in terms of generalizability.

Fluoride’s toxicity from the 1930s to latest NTP report

The next witness, Grandjean, author of “Only One Chance: How Environmental Pollution Impairs Brain Development — and How to Protect the Brains of the Next Generation,” previously testified as an expert witness for the EPA on mercury toxicity. Grandjean established the reference dose and exposure limit for methylmercury used by the EPA, and conducted a benchmark concentration analysis of PFAS (per- and polyfluoroalkyl substances) chemicals.

Grandjean began his testimony by emphasizing that the most vulnerable populations to neurotoxicity are pregnant mothers and babies.

Grandjean provided a long history of research on fluoride toxicity that preceded the latest birth cohort studies. That research began with occupational studies by Kaj Roholm in the 1930s that found evidence of skeletal fluorosis and neurotoxicity.

Research on fluoride’s neurotoxicity also included animal studies discussed in the first phase of the trial by the EPA’s expert witness Kristina Thayer, Ph.D.

Grandjean’s own research also supports the biological plausibility of fluoride’s neurotoxic effects in humans and his own ecological studies linking fluoride exposure to cognitive deficits among children in China, which he said showed that even at lower levels, fluoride impacted cognitive functioning in children.

In 2012, Grandjean published a literature review on the topic the findings of which were consistent with the NTP report published in draft form more than 10 years later, he said.

However, the NTP report, Grandjean said, now had twice as many studies supporting evidence of fluoride’s neurotoxicity.

In the EPA’s opening statement, the agency told the court the NTP’s conclusions were driven by studies that had more than 0.7mg/L in the water.

Connett asked Grandjean to walk through the NTP’s data. Grandjean read out the numbers from Table 6 in the NTP report, showing the vast majority — 18 of the 27 high-quality studies — identified by the NTP were in the 1.5-4 mg/L level, which is lower-level exposure.

And several of the highest quality studies showing lower IQs in children were done in optimally fluoridated areas (0.7 mg/L) areas in Canada.

The NTP report found that “the high-quality studies (i.e., studies with low potential for bias) consistently demonstrate lower IQ scores with higher fluoride exposure.”

Grandjean confirmed that consistency across communities with different characteristics in the NTP report supports the hypothesis that there is a causal relationship between fluoride and neurotoxicity, particularly combined with other sources of data.

Grandjean also pointed out that different magnitudes of effects of fluoride in those different communities were “entirely expected,” adding, “This isn’t an indication that fluoride has variable effects, this is simply an indication of real-world variability.”

We should not just rely on a single study or a couple of studies because of that variability and with fluoride, we have “a massive amount of data” showing there is something really significant going on, Grandjean said.

EPA names surprise rebuttal witness

Just before the court adjourned Thursday, the EPA said they planned to call a rebuttal witness later in the trial, NTP director, Richard Woychik, Ph.D.

EPA attorneys told the court they would call Woychik to possibly rebut the testimony of plaintiffs’ witness Brian Berridge, DVM, Ph.D., the NTP’s scientific director when the NTP fluoride report was produced.

Although NTP scientists finalized the report in May 2022, it was March 2023 before the report was finally released, under a court order. According to emails obtained by FAN via Freedom of Information Act (FOIA) requests, top officials from the U.S. Department of Health and Human Services and the Centers for Disease Control and Prevention blocked the NTP from releasing the report.

Woychik publicly took responsibility for blocking the release of the NTP report. However, FOIA’d emails show it was HHS Assistant Secretary of Health Rachel Levine who blocked it.

Today, almost two years after the NTP scientists finalized the report, the final draft has not yet been published. Instead, the draft report continues to be mired in an ongoing process of repeated peer review, which FAN alleged is an attempt to “weaken, delay, or kill” the report.

Attorneys for FAN plan to call Berridge to discuss the report, the peer-review process and why he signed off on the May 2022 version as a final and complete report that was ready for publication, Connett told The Defender last month.

In December 2023, the 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.

In a blow to the agency, federal Judge Edward Chen said he would allow Berridge’s testimony.

Chen had earlier informed the parties that given that the draft report had been released, he didn’t see merit in further investigating the motives behind the release. He said it was “the science” regarding fluoride’s neurotoxicity, rather than the politics behind the case, that would decide the case.

Both parties agreed to focus on the science and that has been the focus of the trial thus far.

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 is not calling on him to speak to that issue.

Rather, they will question him about the integrity of the scientific process in the report’s production.

Nevertheless, the EPA said it plans to call Woychick to counter, if the EPA deems necessary, aspersions it anticipates Berridge may cast on the NTP publication process.