After the U.S. Environmental Protection Agency (EPA) denied a 2016 petition filed under Section 21 of the Toxic Substances Control Act (TSCA) requesting that EPA consider whether fluoride in drinking water presents an unreasonable risk of injury to human health, a coalition of non-governmental organizations (NGO) promptly filed suit in the U.S. District Court for the Northern District of California. Food & Water Watch v. EPA (No. 3:17-cv-02162-EMC). After a bench trial in 2020, the court held the case in abeyance to wait for a final National Toxicology Program (NTP) Monograph that was issued in August 2024. On September 24, 2024, the court issued its decision, stating that the plaintiffs established by a preponderance of the evidence that the levels of fluoride typical in drinking water in the United States pose an unreasonable risk of injury to the health of the public. The court found that “fluoridation of water at 0.7 milligrams per liter (‘mg/L’) — the level presently considered ‘optimal’ in the United States — poses an unreasonable risk of reduced IQ in children.” The court notes that its finding “does not conclude with certainty that fluoridated water is injurious to public health; rather, as required by the Amended TSCA, the Court finds there is an unreasonable risk of such injury, a risk sufficient to require the EPA to engage with a regulatory response.” The order does not dictate how EPA must respond, but states that “[o]ne thing the EPA cannot do, however, in the face of this Court’s finding, is to ignore that risk.”