US federal health officials warned last week that 100 million Americans risk dental disease due to a lack of fluoride in their drinking water. The Centre for Disease Control and Prevention said it issued new recommendations in part because of the surge in popularity of bottled water in the past decade. Although some bottled waters marketed in the United States contain an optimal amount of fluoride, most contain only a fraction of the one part per million recommended concentration. "Fluoride is needed throughout the lifespan to prevent and control tooth decay. Better use of fluoride can lead to considerable savings in public and private resources and continue the tremendous advances we've made in reducing tooth decay," said CDC Director Dr. Jeffrey Koplan. Fluoridation of community drinking water, which began in the late1940s, and use of other fluoride products, are credited for the dramatic reductions in tooth decay experienced by U.S. residents. In 1999, the CDC included water fluoridation in its list of 10 great public health achievements of the 20th century. Studies show that fluoride prevents the formation, slows the progression, and even reverses newly-forming cavities. The recommended that bottled water manufacturers label bottled water with the fluoride concentration and that an increased labelling of bottled waters on a voluntary basis will allow consumers to make informed decisions on their fluoride intake. The full report is available on the CDC web site.