I'm a medial pathologst and toxicologist and my research over the past 20 to 30 years has involved looking at the effect of toxic substances on development in the fetus and in the infant..... I guess the thing that got me interested in fluroide in the first place was the very very low levels that you find in human breast milk. What that tells me is that throughout evolution we've built up a special mechanism for keeping fluoride away from the developing infant.