Studies show fluoride causes an array of health problems from thyroid problems to bone density issues, and even brain damage. It should never be ingested and your body treats it like a poison (it's actually the main ingredient in rat poison). In fact it's toxicity level is ranked higher than lead, and we all know the dangers of lead poisoning. Once fluoride is put in the water it is impossible to control the dose each individual receives because people drink different amounts of water. The fluoride goes to everyone regardless of age, health or vulnerability.