Water fluoridation
Health and dental organizations worldwide have endorsed its safety and effectiveness. Its use began in 1945, following studies of children in a region where higher levels of fluoride occur naturally in the water. Further research showed that moderate fluoridation prevents tooth decay.
History of fluorine
After 74 years of effort by many chemists, on 26 June 1886, Moissan isolated elemental fluorine. Moissan's report to the French Academy of making fluorine showed appreciation for the feat: "One can indeed make various hypotheses on the nature of the liberated gas; the simplest would be that "we are in the presence of fluorine"."