Water fluoridation is the addition of a chemical to increase the concentration of fluoride ions in drinking water with the purpose of reducing the incidence of tooth decay. Fluoride compounds are found naturally in the ground water in some regions, such as Colorado.. Fluoridation chemicals are typically added to potable water in the form of sodium hexafluorosilicate or hexafluorosilicic acid (also known as hydrofluorosilic acid).
Initial hypotheses for the staining included poor nutrition, overconsumption of pork or milk, radium exposure, childhood diseases, or a calcium deficiency in the local drinking water. In 1931, researchers from the Aluminum Company of America (ALCOA) finally concluded that the cause of the Colorado stain was a high concentration of fluoride ions in the region's drinking water (ranging from 2 to 13.7 ppm) and areas with lower concentrations had no staining (1 ppm or less). Pikes Peak's rock formations contained the mineral cryolite, one of whose constituents is fluorine. As the rain and snow fell, the resulting runoff water dissolved fluoride which made its way into the water supply.
Dental and aluminum researchers then moved toward determining a relatively safe level of fluoride chemicals to be added to water supplies. The research had two goals: (1) to warn communities with a high concentration of fluoride of the danger, initiating a reduction of the fluoride levels in order to reduce incidences of fluorosis, and (2) to encourage communities with a low concentration of fluoride in drinking water to add fluoride chemicals in order to help prevent tooth decay.
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 ppm fluoride content, and low fluoride Wichita Falls. The data is alleged to show less 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 part per million (ppm).
In 1939, Dr. Gerald J. Cox conducted laboratory tests using rats that were fed aluminum and fluoride. The anti-carries data from his studies were described as, "inconclusive" and, "anything but convincing," by fluoride historian Peter Meiers. But Dr. Cox suggested adding fluoride to drinking water (or other media such as milk or bottled water) in order to improve oral health. In 1937, dentists Henry Klein and Carroll E. Palmer had considered the possibility of fluoridation to prevent cavities after their evaluation of data gathered by a Public Health Service team at dental examinations of Native American children. In a series of papers published afterwards (1937-1941), yet disregarded by his colleagues within the U.S.P.H.S., Klein summarized his findings on tooth development in children and related problems in epidemiological investigations on caries prevalence.
In the mid 1940s, four widely-cited studies were conducted. The researchers investigated cities that had both fluoridated and unfluoridated water. The first pair was Muskegon, Michigan and Grand Rapids, Michigan, making Grand Rapids the first community in the world to add fluoride chemicals to its drinking water to try to benefit dental health on January 25, 1945. Kingston, New York was paired with Newburgh, New York. Oak Park, Illinois was paired with Evanston, Illinois. Sarnia, Ontario was paired with Brantford, Ontario, Canada.
In 1951, a member of the Newburgh - Kingston Fluoridation Committee, Katherine Bain, stated: "the technical committee set up to work with that study set itself a goal which it wasn´t able to achieve. It had hoped to keep the study under wraps for ten years, and at the end of ten years come out with a definitive answer about what fluoride did, what its harmful effects might be. As you know, that study and other studies began having such results that people became interested, and the pressure was such that people felt we must go ahead with these programs." The Newburgh-Kingston study has been sharply criticized by the Fluoride History website for its, "ludicrous inadequacy," and for engaging in, "obvious manipulations." In 1952 Nebraska Representative A.L. Miller complained that there had been no studies carried out to assess the potential adverse health risk to senior citizens, pregnant women or people with chronic diseases from exposure to the fluoridation chemicals. A decrease in the incidence of tooth decay was found in some of the cities which had added fluoride chemicals to water supplies. However, tooth decay was declining in similar rates in non-fluoridated cities. The early comparison studies would later be criticized as, "primitive," with a, "virtual absence of quantitative, statistical methods...nonrandom method of selecting data and...high sensitivity of the results to the way in which the study populations were grouped..." in the journal Nature.
The damage in tooth development occurs between the ages of 6 months to 5 years, from the overexposure to fluoride. In its severe form it is characterized by black and brown stains, as well as cracking and pitting of the teeth.
The World Health Organization cautions that fluoride levels above 1.5 milligrams per liter leaves the risk for fluorosis. To protect against this health organizations in some high fluoride areas endorse providing alternative water sources, or removing fluoride from the water. 0.07 – 1.2 milligrams per liter of fluoride is considered to be the optimal level. A CDC evaluation concluded that prevalence of some level of fluorosis among children and adolescents in the United States had increased by from 22.8% in 1986 – 1987 to 32% in 1999 – 2002.
Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States, Morbidity and Mortality Weekly Report, August 17, 2001, Centers for Disease Control and Prevention Many communities need to reduce fluoride exposure. Consumption of water exceeding 10 ppm fluoride has been shown to lead to pathological changes in bone structure, and skeletal fluorosis. Debilitating environmental fluorosis of a portion of the population is a problem in several developing countries, where it is complicated by malnutrition. The effects of skeletal fluorosis can be slowly reversed through a reduction of fluoride intake and improved diet.
Those who question the cost-benefits of fluoridation express the greatest concern for vulnerable populations, and the National Research Council states that children have a higher daily average intake than adults per kg of bodyweight. Those who work outside, or have urine problems also will drink more water. osteosarcoma, a rare bone disease affecting male children, has been associated with fluoride intake. The weight of the evidence, as assessed by independent committees of experts, comprehensive systematic reviews, and review of the findings of individual studies does not support an association between water fluoridated at levels optimal for oral health and the risk for cancer, including osteosarcoma, although a study described as the most rigorous yet by the Washington Post found a relationship among young male boys. The authors' adviser faced an investigation based on his dismissal of the results and an apparent conflict of interest. An epidemiological connection between areas with high intake of silicofluorides and increased lead blood levels in children has been observed in areas fluoridated at the recommended dosage. A 2007 update on this study confirmed the result and noted that silicofluorides, fluosilicic acid and sodium fluosilicate are used to fluoridate over 90% of US fluoridated municipal water supplies.
A panel member of the NRC report, Kathleen M. Thiessen, writes that the report does seem relevant to the debate over the cost-benefits of fluoridation, and that the "margin of safety between 1 mg/L and 4 mg/L is very low" because of the uncontrolled nature of the dosage. In her opinion fluoride intake should be minimized. John Dull, the chair of the panel, stated that "the thyroid changes worry me ... we’ve gone with the status quo regarding fluoride for many years—for too long, really—and now we need to take a fresh look ... I think that’s why fluoridation is still being challenged so many years after it began. In the face of ignorance, controversy is rampant". Hardy Limeback, another panel member, stated "the evidence that fluoridation is more harmful than beneficial is now overwhelming and policy makers who avoid thoroughly reviewing recent data before introducing new fluoridation schemes do so at risk of future litigation". Another panel member, Robert Isaacson, stated that "this report should be a wake-up call" and said that the possible effects on the endocrine gland and hormones are "something that I wouldn’t want to happen to me if I had any say in the matter." But, Tom Maier, an assistant biosciences professor at the OHSU School of Dentistry, pointed out that the NAS panel besides saying the current EPA maximum on fluoride in water is unsafe mainly called for more definitive research and that policy change is not needed at this point.
Excess fluoride consumption has been studied as a factor in the following:
On April 2, 1999, the U.S. Centers for Disease Control and Prevention listed water fluoridation as one of the 10 greatest public health achievements of the 20th century.
Fluoridation of milk is being practiced by the Borrow Foundation in some parts of Bulgaria, Chile, Peru, the Russian Federation, Thailand and the United Kingdom. A pilot fluoridated milk program was in effect in the Haidian district of Beijing, China from 1994 through 1999 where laws forbidding fluoridation were passed, the University of Hong Kong and National Committee for Oral Health work with the Borrow Foundation and some Chinese dentists to re introduce fluoridated milk.
Salt was first fluoridated in Switzerland in 1955 followed by France in 1986 and shortly after by Jamaica and Costa Rica. Costa Rica, Jamaica and Colombia today practice universal salt fluoridation, whereby all salt bound for human consumption is fluoridated, this includes salt that is added to ready prepared food, and where no fluoride free salt is available.
In October 2006, the United States Food and Drug Administration issued a health claim notification permitting water bottlers to claim that fluoridated bottled water can promote oral health. The claims are not allowed to be made on bottled water marketed to infants.