It is noteworthy that fluorine, which is the most abundant halogen and the thirteenth most abundant element in the earth’s crust, was not involved in the ancient evolution of life on Earth as a regular component of organic compounds of living organisms. All the known naturally occurring fluoro-organic compounds are poisonous. The finding of fluorine in teeth enamel, ash of blood, and the yolk and shell of eggs stimulated the search for its physiological role. The effects of fluoride were reported in many enzymatic reactions in research conducted by prominent biochemists Embden, Lohman, Lipmann, Meyerhof, and their coworkers. The use of sodium fluoride helped in understanding the mechanisms of enzyme catalysis in glycolytic and Krebs-cycle pathways.
