The National Toxicology Program's 2024 systematic review of 72 studies concluded with moderate confidence that fluoride exposure at levels found in some water supplies (above 1.5 mg/L) is associated with lower IQ in children. A federal judge ruled the EPA must take regulatory action. While the optimal fluoridation level (0.7 mg/L) is below the concerning threshold, the finding validated decades of concerns that were dismissed as pseudoscience.