The dental association refuted claims that fluoride is a Neurotoxin and that's  not scientific enough for me.  The 12 members of the National Research Council reviewed the last 10 years of research on fluoride and concluded unanimously that the current maximum contaminant level for fluoride is unsafe and should be lowered.  The fact is that the batches of fluorosilicic acid differ from one to the other and they are not tested for safety by any agency. Contaminants accumulate in the body.