There's no doubt about it: Fluoride should not be ingested. Even scientists from the EPA's National Health and Environmental Effects Research Laboratory have classified fluoride as a "chemical having substantial evidence of developmental neurotoxicity.” Furthermore, according to the Centers for Disease Control and Prevention (CDC), 41 percent of American adolescents now have dental fluorosis—unattractive discoloration and mottling of the teeth that indicate overexposure to fluoride.