LAW360: A Harvard epidemiologist testified in a high-stakes bench trial over environmental groups’ efforts to get the U.S. Environmental Protection Agency to ban fluoride in 200 million Americans’ drinking water that there is “definitely a causal relationship” between fluoride exposure and neurotoxicity, even at low exposure levels.

Danish epidemiologist Philippe Grandjean, who is an adjunct professor at Harvard University and chair of environmental medicine at the University of Southern Denmark, took the stand Thursday on the second day of a two-week bench trial in San Francisco before U.S. District Judge Edward Chen, part of litigation first launched by Food & Water Watch Inc., the Fluoride Action Network and other groups against the U.S. Environmental Protection Agency in April 2017.

The lawsuit seeks to force the EPA to make a new federal rule under the Toxic Substances Control Act that would ban fluoride from being added to drinking water. Local municipalities have added fluoride to the water for decades to boost public dental hygiene and prevent dental decay.

During his direct examination, Grandjean testified he pooled data from multiple animal and human fluoride exposure studies from around the world, including studies conducted in India and China, to conclude there is “definitely a causal relationship” between fluoride exposure and neurotoxicity and brain development. He said the studies show children whose mothers were exposed to high levels of fluoride while they were in the womb have IQ scores approximately seven points lower than children from non-exposed groups.

Grandjean noted that his research into fluoride began over a decade ago, when he included the chemical in a list of roughly a dozen chemicals he found to be capable of crossing the blood-brain barrier, which protects the brain, and were “definitely toxic to the brain development in humans.”

He emphasized fetuses are particularly vulnerable because certain brain development processes must occur in a particular order.

“If something goes wrong, you don’t have a chance later on,” Grandjean said. “You’re stuck with the brain you started developing early in life. That’s why a lot of us have concerns about these chemicals that can interfere with these processes.”

Grandjean testified that fluoride is “virtually insoluble” in water and can’t be boiled off, and when it is inhaled or ingested, roughly half of the chemical ends up being stored in the human skeleton, with the rest either excreted or distributed throughout the body.

“We know that fluoride does pass the blood-brain barrier in adults, it does enter the brain,” he said. “The question is whether there are relevant toxicity changes, and that’s very difficult to assess, because we cannot get fresh brain tissue for obvious reasons, so we don’t really have that evidence.”

Grandjean agreed with other professors testifying in the case on behalf of the plaintiffs who have found links between high fluoride exposure and lower IQ levels. He conducted his own study in a Chinese community on children whose mothers drank different levels of fluoridated water; the results from that study aligned with others, indicating higher levels of fluoride resulted in lower cognitive functioning, as evidenced by IQ scores.

Grandjean noted the studies use IQ scores, which are based on standardized tests, but the tests don’t consider changes in sensory perception, or the behavioral and psychological impacts of fluoride exposure, even though neurotoxins can impact those brain functions as well.

He also countered criticisms by the defense’s suggestion that variabilities in water fluoride levels are too imprecise to support the conclusion that fluoride impacts cognitive function. Grandjean said a more reliable method of studying fluoride levels is by looking at fluoride levels in a mother’s urine samples.

“If you go back in history, we were concerned about lead in gasoline … There’s no practical way for us to measure lead in car exhausts and then relate that to child development,” he said. “Likewise with fluoride. It’s just not practical. We have to accept what counts here is what gets into the body, and we know that water fluoridation is an important source. What really counts in toxicology is what gets into the body and what gets into the fetal brain.”

Before trial recessed for the day, plaintiffs’ counsel Michael Connett of Waters Kraus & Paul LLP asked Grandjean bluntly: “Is neurotoxicity a hazard of fluoride exposure?”

“It definitely is,” Grandjean replied.

Before Grandjean took the stand, the plaintiffs called Bruce Lanphear, a professor at Simon Fraser University, who testified on papers he co-authored regarding the Maternal-Infant Research on Environmental Chemicals, or MIREC, project in Canada. Lanphear noted the papers were extensively reviewed, including by three independent third parties.

“We knew that fluoride research was not only contentious, but also that it could affect policy, so we wanted to get it right,” he said.

The studies concluded that an increase in prenatal fluoride exposure results in lower IQ rates in children. Lanphear said the relationship is mostly linear, even in small concentrations, and the impact of fluoride on IQ is more pronounced when there is a mother with iodine deficiency, or hyperthyroidism related to iodine deficiency.

He noted the study included more than 1,000 mothers, roughly 100 with hyperthyroidism; only women who said they drink tap water were included, and it excluded women with cancer or other serious health conditions.

But under cross and redirect examination, Lanphear acknowledged mothers in the study may have moved from different areas in Canada that don’t have fluoride added to the drinking water. Only 38% of Canadian communities have fluoride added to the public water supply, while 75% of communities in the U.S. have water supplies with added fluoride, according to Lanphear.

The trial will resume Friday morning with the continuation of Grandjean’s direct examination.

The legal fight went to a first bench trial in 2020, with the environmental groups asking the court to declare that fluoride in tap water posed a risk to human health. But Judge Chen suspended litigation for years to give the EPA time to conduct another study and reevaluate fluoride’s risks. Litigation resumed in October 2022.

The environmental groups are represented by C. Andrew Waters and Michael Connett of Waters Kraus & Paul LLP and Christopher T. Nidel of Nidel & Nace PLLC.

The EPA is represented by Brandon N. Adkins and Paul A. Caintic of the U.S. Department of Justice’s Environment and Natural Resources Division and Emmet P. Ong of the U.S. Attorney’s Office for the Northern District of California.

The case is Food & Water Watch Inc. et al. v. EPA et al., case number 3:17-cv-02162, in the U.S. District Court for the Northern District of California.

–Editing by Caitlin Wolper.

Original article online at: https://www.law360.com/articles/1792908/harvard-professor-testifies-fluoride-is-definitely-neurotoxic?copied=1