The most intriguing news about fluoride is the evidence suggesting that fluorine is an essential element for rat growth and for mouse fertility.1-3 Traces, such as occur naturally in "normal" diets, apparently prevent deficiencies. Whether an essential role of such traces can be demonstrated for normal human development or not, fluoride is important for man because, in slightly larger amounts, it reduces the incidence of dental caries, whereas in excess, depending on the dose, it exhibits toxic or lethal effects.
Water fluoridation, a major contribution by dentistry to preventive medicine, ranks among the great public health developments of this century. The practice of water fluoridation at 1 ppm fluoride in temperate climates rests firmly on the demonstrated reduction in decay observed as the concentration of fluoride naturally present increases from traces to about 1 ppm in the water supplies of communities in the United States and elsewhere. Since water