A Harvard study published in a US National Institute of Environmental Health Sciences journal, Environmental Health Perspectives
, found a relation between lower IQ levels and flouridated water. The article title states a "cause/effect" scenario that can't really be determined from correlative evidence, (article authors are notorious for making the jump from "correlation" to "cause/effect") but the study does raise some serious questions. Other studies have suggested links between flouride and bone cancer.
Read the Reuters article here:
Harvard Study Finds Fluoride Lowers IQ - Published in Federal Gov't Journal