Mass medication through our public water supply is a very dangerous precedent. Most European countries have banned fluoride in their water supplies due to health and safety fears. There is strong scientific evidence that fluoride causes many health problems - it weakens the immune system, it is linked to increased cancer death rates and osteosarcoma rates in young males, and increased hip fractures rates, it adversely affects genes and chromosomes, reduces insulin production by the pancreas, affects thyroid and kidney functions, increases the infant mortality rate in undernourished populations and also causes brittle teeth.
Natural fluoride is different to the "artificial" fluoride put in water - even so, in areas where it occurs naturally to a significant degree, there are health problems. Artificial fluoride is a waste product of the steel and fertiliser industries and requires safe storage and disposal. Even fluoridated toothpaste carries a warning not to swallow.