On Friday, the Environmental Protection Agency officially appealed a federal court ruling which ordered the agency to take action against the risks posed by fluoridation chemicals.

The EPA staked their appeal on three main arguments, including a belief that the plaintiffs' lack standing, the judge improperly considered new evidence, and the district court went beyond its authority in its management of the case.

The EPA's appeal is the latest development in a nearly decade-long legal saga between the EPA, and parents of children impacted by water fluoridation, as well as the Fluoride Action Network (FAN). The lawsuit began following the EPA's 2016 decision to deny the plaintiff's petition under the Toxic Substances Control Act (TSCA). In September 2024, Judge Edward Chen found that fluoridation of water at 0.7 milligram per liter "poses an unreasonable risk of reduced IQ in children".

Chen said the risk is sufficient to require the EPA to enact a regulatory response. However, he said that TSCA only granted him the authority to direct the EPA to take action against the risk, but not to prescribe the specifics of its response, which could range from a national warning to an outright ban.

In the final days of the Biden administration the EPA filed their appeal, and now, under leadership appointed by President Donald Trump, the EPA has decided to continue fighting the judge's ruling.

The EPA contends that at least one of the plaintiffs' water contains naturally occurring fluoride and thus they cannot prove injury as a result of community water fluoridation. The agency also claims that the Judge's decision to allow studies which were published after the original 2016 TSCA petition violated the act.

"The district court violated TSCA Section 21 by permitting Plaintiffs to rely on evidence not first presented to EPA in the petition and reviewed by EPA in denying the petition. The court's final merits ruling overwhelmingly relied on voluminous evidence that did not even exist at the time of the original petition," the EPA and Department of Justice wrote in their appeal.

Michael Connett, the lead attorney representing the Fluoride Action Network and plaintiffs, said the EPA is arguing the court should have ignored relevant science published after 2016.