Water fluoridation

Water fluoridation is the practice of adding fluoride compounds to water with the intended purpose of reducing tooth decay in the general population. Many North American and Australian municipalities fluoridate their water supplies in the belief that this practice will reduce tooth decay at a low cost. Currently 66% of United States residents on public water supplies have fluoridated water.^[1]

Water purveyors typically add a fluoride in the form of sodium hexafluorosilicate or hexafluorosilicic acid,^[2][3] at a level between 0.7 and 1.2 ppm. These compounds originate as side products from the processing ("defluorination") of phosphate ores to prepare fertilizers, food additives, etc.^[4][5] Fluorides such as sodium fluoride (NaF), sodium monofluorophosphate ("SMFP" or "MFP", Na₂FPO₃), tin(II) fluoride ("Stannous fluoride", SnF₂), and amine fluorides are common ingredients in toothpaste.

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History

While the use of fluorides for prevention of dental caries was discussed in the 19th century in Europe,^[6] community water fluoridation in the United States owes its origin in part to the research of Dr. Frederick McKay, who pressed the dental community for an investigation into what was then known as "Colorado brown stain."^[7] In 1909, of the 2,945 children seen by Dr. McKay, 87.5% had some degree of stain or mottling. All the affected children were from the Pikes Peak region. Despite having a negative impact on the physical appearance of their teeth, the children with stained or mottled teeth also had fewer cavities than other children. McKay brought the problem to the attention of Dr. G.V. Black, and Black's interest into the Colorado stain led to greater interest throughout the dental profession.

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.^[7] 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).^[8] 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 research then moved toward determining a safe level for fluoride in 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 prevent the Colorado stain, currently known as dental fluorosis, and (2) to encourage communities with a low concentration of fluoride in drinking water to increase the fluoride levels in order to help prevent tooth decay.

The classic epidemiological study to attempt to determine the optimal level of fluoride in water was led by Dr. H. Trendley Dean, a dental officer of the U.S. Public Health Service, in 1934.^[9][10] His 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 level of fluoride which minimized the risk of severe fluorosis but had positive benefits for tooth decay was 1 part per million (ppm). In 1939, Dr. Gerald J. Cox^[11] conducted laboratory tests on fluoride and suggested adding fluoride to drinking water (or other media such as milk or bottled water) in order to improve oral health.^[12] 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.^[13] 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 modify its fluoride levels in drinking water to benefit dental health on January 25, 1945.^[14] Kingston, New York was paired with Newburgh, New York.^[15] Oak Park, Illinois was paired with Evanston, Illinois. Sarnia, Ontario was paired with Brantford, Ontario, Canada.^[16] The research found a decrease in the incidence of tooth decay in cities which had added fluoride to water supplies.

Controversy

Main article: Water fluoridation controversy

Water fluoridation by public authorities has provoked controversy. Advocates of water fluoridation say that fluoridation is similar to fortifying salt with iodine, milk with vitamin D and grape juice with vitamin C and say it is an effective way to prevent tooth decay. Those opposed to public fluoridation of drinking water contend that water fluoridation can have harmful health effects such as dental fluorosis and bone cancer. Some opponents claim that fluoridation takes away individual choice as to the substances a person ingests and that it amounts to mass medication.

Bottled water and fluoridation

Currently, there is some concern among dental professionals that the growing use of bottled water may decrease the amount of fluoride exposure people will receive.^[17] Some bottlers such as Dannon have begun adding fluoride to their water. ^[18] Most bottlers, however, do not add fluoride, and fluoride concentrations are not usually labeled on the bottle. As a result, people who have fluoridated water supplies may receive less than the amounts of fluoride that fluoride proponents recommend if they choose bottled water over tap water. However, if consumers are merely choosing bottled water over other packaged drinks, such as orange juice or soda (when the latter is produced using water which has not been fluoridated), the effects may be absent, especially because consumers will still turn to tap water for cooking (i.e. preparing pasta or making bread).

Malfunctions in water fluoridation equipment

Water fluoridation equipment has, on occasion, malfunctioned in the United States. Perhaps the worst incident in the United States occurred in Hooper Bay, Alaska in 1992. When fluoridation equipment failed, a large amount of fluoride was released into the drinking water supply and 296 people were poisoned; 1 person died,^[19] marking the first reported death due to fluoride toxicity caused by drinking water from a community water system.^[20]

International status

Canada

Approximately 40% of the Canadian population receives fluoridated water^[21]

Implementation of fluoridation usually lies with provincial or city governments. Brantford, Ontario became the first city in Canada to fluoridate its water supplies in 1945. In 1955, Toronto approved water fluoridation, but delayed implementation of the program until 1963 due to a campaign against fluoridation by broadcaster Gordon Sinclair.^[22] The city continues to fluoridate its water today.^[23] There have been some recent decreases in the amount of fluoridation used, however, from 1 mg per litre to between 0.6 and 0.8 mg per litre. Historically, British Columbia has been the province with least percentage of its population receiving fluoridated water;^[24] Greater Vancouver Water District member municipalities within the Metro Vancouver region receive water supplies that do not have added fluoride. ^[25]

Europe

In the United Kingdom 10% of the population receives fluoridated water - including two major cities: Birmingham and Newcastle upon Tyne.^[26]

Some provinces of Spain allow drinking water fluoridation, but the extent of that practice is only 10% population coverage.^[27]

France does not fluoridate its water supply. As a consequence, in this country, fluoride chemicals are not included in the list of 'chemicals for drinking water treatment'. This is due to ethical as well as medical considerations. See: Directeur de la Protection de l'Environment, August 25, 2000).^[28] However, fluoridated salt is widely available.^[29]

In Switzerland since 1962 two fluoridation programmes had operated in tandem: water fluoridation in the City of Basel, and salt fluoridation in the rest of Switzerland (around 83% of domestic salt sold had fluoride added). However it became increasingly difficult to keep the two programmes separate. As a result some of the population of Basel were assumed to use both fluoridated salt and fluoridated water. In order to correct that situation, in April 2003 the State Parliament agreed to cease water fluoridation and officially expand salt fluoridation to Basel.^[30]

Oceania

Australia has fluoridation in all but one state, Queensland, in which water fluoridation is under local government control. However, on 5 December 2007 Queensland Premier Anna Bligh announced fluoridation of most of Queensland's water supply will begin in 2008. ^[31] The City of Geelong, west of Melbourne, does not fluoridate its water supplies. This is despite the fact that all of Melbourne's water is fluoridated. The first town to fluoridate the water supply in Australia was Beaconsfield, Tasmania in 1953.^[32]

New Zealand has fluoridated nearly all water-supplies except those in remote areas. The use of water fluoridation first began in New Zealand in Hastings in 1954. A Commission of Inquiry was held in 1957 and then its use rapidly expanded in the mid 1960s. ^[33]

United States

As of May 2000, 42 of the 50 largest U.S. cities have water fluoridation.^[34] According to a 2002 study,^[35] 67% of Americans are living in communities with fluoridated water. As of 2001, 19 states have at least 75% of their population receiving fluoridated water.^[36] There is a CDC database for researching the water fluoridation status of neighborhood water.^[37]

In 1998, 70% of people polled in a survey conducted by the American Dental Association believed community water should be fluoridated, with 18% disagreeing and the rest undecided.^[38]

The issue of whether or not to fluoridate water supplies occasionally arises in local governments. For example, on November 8, 2005, citizens of Mt. Pleasant, Michigan voted 63% to 37% in favor of reinstating fluoridation in public drinking water after a 2004 ballot initiative ceased water fluoridation in the city.^[39] At the same time, voters in Xenia, Ohio; Springfield, Ohio; Bellingham, Washington; and Tooele City, Utah all rejected water fluoridation.^[40]

The cost of fluoridating water supplies in the United States has been researched.^[41] In cities with a population of over 50,000 people, fluoridation costs 31 cents per person per year. The cost rises to $2.12 per person in cities with a population below 10,000.

Other

The government of South Africa supports the fluoridation of water supplies.^[42]

In Brazil, about 45% of cities have a fluoridated water supply. Government studies reported a decrease in cavities in the affected populations of between 40% and 80%.^[43]

In Chile 70.5% of the population receive fluoridated water (10.1 million adjusted, 604,000 naturally occurring).^[44]

Israel adopted fluoridation beginning in 1981. By 2002, more than 2 million people (roughly one-third of the population) were receiving fluoridated water.

See also

• Fluoride therapy
• Fluorine deficiency

References