16 American Dental Association the most accurate results, a state certified laboratory that conducts drinking water tests should be used for fluoride testing. For a list of state certified laboratories, contact the local, county or state water/health department. The EPA does not specifically recommend testing private wells for the level of fluoride. However, if a household with a private well has children under 16 years of age, their health professionals will need to know the fluoride level of the well water prior to consideration of prescription of dietary fluoride supplements8 or to counsel patients about alternative water sources to reduce the risk of fluorosis if the natural fluoride levels are above 2 mg/L. Dietary fluoride supplements (tablets, drops or lozenges) are available only by prescription and are intended for use by children ages six months to 16 years living in nonfluoridated areas and at high risk of developing tooth decay. Your dentist or physician can prescribe the correct dosage.8 Additional information on this topic can be found in this Section, Question 12 and in the Safety Section, Questions 21, 27, 28 and 29. 5. What additives are used to fluoridate water supplies in the United States? Answer. Sodium fluoride, sodium fluorosilicate and fluorosilicic acid are the three additives approved for use in community water fluoridation in the United States. Sodium fluorosilicate and fluorosilicic acid are sometimes referred to as silicofluoride additives. Fact. The three basic additives used to fluoridate water in the United States are: 1) sodium fluoride which is a white, odorless material available either as a powder or crystals 2) sodium fluorosilicate which is a white or yellow-white, odorless crystalline material and 3) fluorosilicic acid which is a white to straw- colored liquid.22 Water fluoridation began in the U.S. in 1945 with the use of sodium fluoride the use of silicofluorides began in 1946 and by 1951, they were the most commonly used additives.23 First used in the late 1940s, fluorosilicic acid is currently the most commonly used additive to fluoridate communities in the United States.24 To ensure the public’s safety, regardless of where the additives are manufactured, they should meet safety standards for water treatment in the U.S.22 Specifically, additives used in water fluoridation should meet standards of the American Water Works Association (AWWA). With respect to NSF/ANSI certification, fluoride additives are considered no different than other water additives. Fluoride additives, like any other water additive should also meet NSF/ANSI Standards.22 In the United States, the authority to regulate products for use in drinking water, including additives used to fluoridate community water systems, rests with individual states. In 2013, AWWA reported that 47 states had adopted the NSF/ANSI Standard 60 which specifies the product quality with validation supplied by independent certification entities.22 To ensure the public’s safety, regardless of where the additives are manufactured, they should meet safety standards for water treatment in the U.S. Additional information on the topic of fluoride additives can be found in the Fluoridation Practice section of this publication and at the CDC’s fluoridation website, “Water Operators and Engineers” at https://www.cdc. gov/fluoridation/engineering/index.htm. 6. Is there a difference in the effectiveness between naturally occurring fluoridated water (at optimal fluoride levels) and water that has fluoride added to reach the optimal level? Answer. No. The dental benefits of optimally fluoridated water occur regardless of the fluoride’s source. Fact. Fluoride is present in water as “ions” or electrically- charged atoms.25 These ions are the same whether acquired by water as it seeps through rocks and sand or added to the water supply under carefully controlled conditions.