1988. Dr. Phyllis J. Mullenix is asked to test fluoride toxicity in rats by her new employers, the Forsyth Dental Research Institute. She assumed that her results would be negative - but to her astonishment, she found a positive correlation between blood levels of fluoride and neuronal toxicity: in lay terms, fluoride was able to get into the brain of rats at blood levels similar to those found in humans. The paper was published in 1994: Neurotoxicity of sodium fluoride in rats. The following video is of poor quality: bad sound, bad lighting, but it shows that Dr. Mullenix is a serious researcher.