For decades, concerns about fluoride's neurological effects were dismissed as conspiracy theory. In 2024, the NTP published findings showing IQ decreases as fluoride exposure increases, particularly above 1.5 mg/L. A federal judge ruled fluoride in water poses an 'unreasonable risk' and ordered the EPA to address it. The controversy remains active — the NTP study has critics, but the fact that government scientists found any IQ association validated what was long dismissed.