Consider this quote on fluoride and developing fetus brains:

* "An earlier study by Mullenix et al., reported in Nevrotoxicology and Teratology, in 1995, found that animals exposed to fluoride at various stages of gestation suffered either permanent hyperactivity if exposed prenatally, or became "the rat version of couch potato" if exposed after birth, though there was no elaboration of exactly what that is.

The Natick folks say "there is good evidence that fluoride . . . affects the IQ and behavioral patterns of the developing fetus at doses that are not toxic to the mother."

The International Society for Fluoride Research has also reported studies implicating fluoride in the rising rates of Down's syndrome, chronic fatigue syndrome and sleep disorders."
http://www.pwgazette.com/fluoride.htm