The health effects of a cavity-fighting chemical backed by health providers for decades will be on trial starting Wednesday, marking a unique development in implementation of the EPA’s landmark chemicals law.

A federal judge in California will decide if adding fluoride to the drinking water of 200 million Americans is too risky for children’s developing brains based on research showing it could lower their IQs.

If Judge Edward M. Chen decides fluoride poses an unreasonable risk, the Environmental Protection Agency would have to restrict its drinking water use in some way.

The case, Food & Water Watch Inc. v. EPA, is the first-ever trial challenging the EPA’s dismissal of a citizens’ petition to compel a regulation using a section of the Toxic Substances Control Act (TSCA) that allows such petitions. It also puts a judge in the uncommon role of judging science without deference to a federal agency.

The outcome could affect the EPA’s chemicals oversight, attorneys said in recent interviews.

Chen, with the US District Court for the Northern District of California, has scheduled the case for a bench trial of up to 10 days.

Public Health

During those two weeks, a coalition of concerned advocacy groups and individuals led by Food & Water Watch will take on a core tenet of public health.

For 75 years, health professionals have encouraged public water systems to add fluoride to drinking water to protect communities.

Fluoride strengthens teeth and reduces cavities by about 25%, according to the Centers for Disease Control and Prevention. “Community water fluoridation has been shown to save money both for families and for the US health care system,” it says.

Yet too much fluoride can be risky, health professionals acknowledge. High concentrations of fluoride increases the risk of skeletal fluorosis, which weakens bones and causes pain and tenderness in major joints.

The EPA limits the amount of fluoride in drinking water to 4 milligrams per liter of water (mg/L). The enforceable standard reflects the agency’s knowledge that high levels of fluoride occur naturally in some parts of the country and it can cost too much for some systems to reduce fluoride to 0.7 mg/L, which is the concentration the Department of Health and Human Services recommends.

Fluoride’s risks in drinking water is the only issue in this case.

Other uses, like fluoride in toothpaste, won’t be discussed, and evidence about fluoride’s benefits won’t be allowed. TSCA specifies that determinations of “unreasonable risk of injury to health” must be made “without consideration of costs or other nonrisk factors.” That means evidence on fluoride’s benefits can’t be introduced, Chen ruled in 2020.

The HHS’ recommended drinking water concentration is too high and is harmful, according to the plaintiffs coalition.

Fluoride passes through the placenta, gets into the developing fetus’ brain, and reduces IQ, they said in pretrial submissions. The result is that the “vast majority” of 72 human studies found an association between fluoride and reduced IQ, they said referencing a draft government analysis.

That means roughly two million pregnant women and 400,000 formula-fed babies exposed to the fluoride in water are at risk, the plaintiffs told the court. TSCA requires the agency to consider injuries chemicals pose to sensitive and highly exposed people as it analyzes the substances’ risks.

The EPA has examined the science, including a draft National Toxicology Program analysis of fluoride that has featured prominently in court hearings.

“Plaintiffs have not provided a scientifically defensible basis to conclude that developmental neurotoxicity is a hazard of fluoride exposure under the conditions of use—at concentrations of 0.7 mg/L,” the Department of Justice, which represents the EPA, maintains in pretrial submissions.

The scientific evidence is insufficient to reach the informed risk determination TSCA requires, DOJ said.

No Deference

Chen is in the rare position of being asked to judge the science behind the agency’s rulemakings.

The section of TSCA that authorizes citizens’ petitions, also says petitioners who later sue the EPA for denying their petition must be provided an opportunity for a “de novo” review by the court.

The court is authorized to review the entirety of the administrative record developed by the EPA and to allow new facts and information be introduced into evidence, which Chen chose to do, said Lynn Bergeson, managing partner of Bergeson & Campbell PC, which specializes in chemical laws and regulations.

The de novo review that TSCA offers to weigh the science in a district court case is unique, said Alexandra Dapolito Dunn, a partner at Baker Botts LLP, who specializes in environmental law and previously served as the EPA’s assistant administrator for chemical safety and pollution prevention.

“The agency gets no deference. Its evidence is as good as the judge thinks it is,” said Robert M. Sussman, an attorney in private practice who specializes in TSCA and served as the EPA’s Deputy Administrator under former President Bill Clinton.

Many judges wouldn’t want to take on a de novo review of science, he said. They’ll think “I’ve got to find a way to go with the agency or we’ll be lost in the complexity of the science.”

Chen is in the position of making determinations much like judges may be invited to do if the US Supreme Court overrules the Chevron doctrine, Bergeson said. The Chevron doctrine directs courts in regulatory cases to defer to the agency’s reasonable interpretation. The top court is set to weigh in on the doctrine this year.

De novo reviews of science, like that in the Food & Water Watch case, mean courts have to deal with a good amount of uncertainty, she said.

Overturning Chevron deference wouldn’t directly change the scientific challenge district courts face in TSCA trials challenging the EPA’s denial of a citizens petition, Dunn said. But it would mean agencies’ interpretations of unclear or ambiguous statutory language would no longer get deference, she said.

Defining Unreasonable Risk

Whatever decision Chen makes could provide insight into how courts define unreasonable risk, Sussman said.

The statute doesn’t define the term, but the law requires the EPA to regulate any chemical meeting to that standard so it no longer poses as much potential to injure people or the environment.

If Chen makes a call about fluoride’s risks, he’ll have to explain his reasoning: the criteria he used to decide whether adding it to drinking water is an unreasonable risk. Sussman said. “By defining unreasonable risk, the judge would put some meat on the law’s bones.”

The case also is likely to open the door to more petitions from interested parties. That can include states, as shown by a recent Washington state request that the EPA issue a rule eliminating the amount of polychlorinated biphenyls that can be in consumer products.

Groups will try to “leap frog the normal EPA process” and force the agency to control a chemical that wasn’t on a list of substances it’s already teed up for a years-long process of examination and possible regulation, Sussman said.

Even though the EPA denies most petitions, petitioners will file their requests to lay the groundwork for a trial where they’ll try to get new evidence before the court, he said.

The case is Food & Water Watch Inc. v. EPA, N.D. Cal., No. 17-cv-02162, trial begins 1/31/24.

To contact the reporter on this story: Pat Rizzuto in Washington at

To contact the editors responsible for this story: Zachary Sherwood at; Maya Earls at

*Original full-text article online at: