John Yiamouyiannis PhD.|
Author of "Fluoride: The Aging Factor" (Three editions: 1983, 1986, 1993) which shows what the fluoride ion (in all its guises) does to the human body. He writes "There may be no safe level of fluoride."
He worked with founder of the (US) National Cancer Institute (NCI) Dr Dean Burk in the mid 1970s proving the fluoride-cancer link through epidemiology.
This video was from 1992.