Talk about foot-dragging! Incredibly, it took the NCI twelve years to finish its tests, finding "equivocal evidence" that fluoride caused bone cancer in male rats. Under further direction of Congress, the NCI studied cancer trends in the U.S., and found nationwide evidence of "a rising rate of bone and joint cancer at all ages," especially in youth, in counties that had fluoridated their water, but no such rise was seen in "non-fluoridated" counties.
In more detailed studies, for areas of Washington state and Iowa, NCI found that from the 1970s to the 1980s bone cancer for males under 20 had increased by 70 percent in the fluoridated areas of these states, but had decreased by 4 percent in the non-fluoridated areas. Sounds pretty conclusive to me, but the NCI set some fancy statisticians to work on the data, to conclude that these findings, too, were "spurious." Dispute over this report drove the federal government to one of its favorite ploys in virtually every area: the allegedly expert, bipartisan, "value-free" commission.
http://www.lewrockwell.com/rothbard/rothbard85.html