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.
Water fluoridation in the United States
A study of varying amounts of fluoride in water was led by Dr. H. Trendley Dean, a dental officer of the U.S. Public Health Service. In 1936 and 1937, Dr. Dean and other dentists compared statistics from Amarillo, which had 2.8 – 3.9 mg/L fluoride content, and low fluoride Wichita Falls. The data is alleged to show fewer cavities in Amarillo children, but the studies were never published. Dr. Dean's research on the fluoride-dental caries relationship, published in 1942, included 7,000 children from 21 cities in Colorado, Illinois, Indiana, and Ohio. The study concluded that the optimal amount of fluoride which minimized the risk of severe fluorosis but had positive benefits for tooth decay was 1 mg per day, per adult. Although fluoride is more abundant in the environment today, this was estimated to correlate with the concentration of 1 mg/L.