Fluoridation

Definition

Fluoridation is the addition of fluoride to water supplies to help prevent tooth decay .

Description

The element fluorine is the seventeenth most abundant element in the earth's crust. It occurs as fluoride ion in combination with other elements such as sodium. Most water supplies naturally contain low levels of fluoride. In much of the United States, as well as in other parts of the world, fluoride is added to community water systems to bring fluoride levels up to the recommended amount for preventing teeth decay: 0.7–1.2 parts of fluoride to 1 million parts of water (parts per million or ppm). The levels of naturally occurring fluoride in fresh water range from less than 0.1 ppm to more than 13 ppm. Seawater contains about 1.5 ppm. As of 2000, about 162 million Americans—two-thirds of the population—were served by fluoridated water systems.

Mode of action

Systemic fluorides, including fluoridated water and prescription fluoride supplements supplied as tablets, drops, or lozenges, can be incorporated into the enamel of children's developing teeth. The enamel that covers the crown, the part of the tooth that is above the gum, is made of a substance called hydroxyapatite. When enough fluoride from water, supplements, food, or other sources enters the bloodstream and reaches the teeth while the enamel is forming, the fluoride can replace a piece of the hydroxyapatite molecule to form fluorapatite. Thus fluoride becomes part of the tooth enamel. Fluoride makes the tooth more resistant to acids produced by the bacteria that cause tooth decay. These acids dissolve the enamel, causing cavities. Fluoride in the enamel appears to do the following:

• make the enamel less susceptible to bacterial acids
• reduce the bacteria's ability to produce acid
• reduce the number of bacteria in plaque deposits

It is unlikely that sufficient fluoride will be incorporated into the enamel throughout the years of crown formation. With optimally fluoridated water (1 ppm) as the primary source of fluoride, a child would have to drink two quarts of water every day for 12 to 14 years to incorporate fluoride into all of the baby and adult teeth as they form. The child would be ingesting about 2 mg. of fluoride daily.

Topical fluorides are applied directly to the surfaces of fully-formed teeth. Fluoridated water acts as a topical—as well as a systemic—source of fluoride. Other topical fluorides include fluoridated toothpastes and mouthwashes and fluoride gels that are applied to children's teeth at dental examinations. Topical fluoride is the most effective mineral for renewing or remineralizing the surface layers of enamel and dentin as they wear out and are eaten away by acids from food and bacteria. Fluoride remineralization makes the tooth surface more resistant to decay and reverses early decay processes. Thus topical fluorides help prevent decay in both children and adults. Systemic fluorides also can provide topical protection because they are incorporated into the saliva that bathes the teeth.

Sources of fluoride

Fluoridated water is a major source of fluoride. Most bottled water contains only trace amounts of fluoride. Filtered water and well water vary greatly in their fluoride content. Children who drink water that is low in fluoride may be given fluoride supplements.

Fluoride occurs in many different foods and is also added to some foods. Fruits and vegetables may contain more than 0.2 mg of fluoride per serving, depending on where they were grown and whether fluoridated water was used for irrigation and processing. Most seafood is high in fluoride. The amount of fluoride in beverages depends on the amount of fluoride in the water used to make them. Many vitamins and medicines also contain fluoride. Most baby food is made with nonfluoridated water.

Fluoridated toothpastes and mouthwashes contain high amounts of fluoride. A tube of fluoridated toothpaste may contain as much as 1 to 2 gm of fluoride. Nonprescription mouthwashes can contain up to 120 mg of fluoride. Children between the ages of two and six swallow about 33 percent of the toothpaste they use; children between seven and 15 swallow about 20 percent. The average child using the typical amount of fluoridated toothpaste will swallow or absorb 0.5 to 1.0 mg. of fluoride per brushing. Much of this fluoride is excreted.

It is believed that fluoridated water is between 20 and 60 percent effective in preventing cavities in children and adults. Early studies suggested that water fluoridation was eliminating tooth decay in children. However, other factors are recognized in the early 2000s as having contributed to the decline in dental cavities. The widespread use of fluoridated toothpastes and mouthwashes has increased children's sources of fluoride significantly. Furthermore, both children's and adults' knowledge about dental care and dental hygiene has improved in the last quarter of the twentieth century.

General use

History

In the early twentieth century a young dentist in Colorado Springs, Colorado, named Frederick McKay, noticed that many local residents had brown stains on their permanent teeth and that their teeth were surprisingly resistant to decay. McKay eventually discovered that this "mottling"—as he called it—resulted from high levels of naturally occurring fluoride in the drinking water.

The first fluoridation of a public water system took place in Grand Rapids, Michigan, in 1945. By the 1950s and 1960s increasing numbers of communities were fluoridating their water using by-products from the phosphate fertilizer industry. The practice became mired in controversy, and it remains so in the first decade of the twenty-first century. Since the decision to fluoridate usually is made at the local level, by public officials or a vote of the people, fluoridation has become a political as well as a scientific controversy.

Proponents

Proponents of water fluoridation argue the following:

• It significantly reduces tooth decay, both before and after tooth enamel has formed.
• The fluoride levels used are completely safe.
• The children of parents who are poorly informed about dental hygiene and cavity prevention or who cannot afford dental treatment are still protected against tooth decay.

Most government agencies and scientific and professional organizations agree that water fluoridation is safe and effective in preventing tooth decay and cost-effective in that it reduces the need for expensive dental treatment. Among the organizations that endorse fluoridation of water supplies are the following:

• American Academy of Pediatric Dentistry
• American Dental Association
• American Medical Association
• National Institute of Dental and Craniofacial Research
• U.S. Centers for Disease Control and Prevention (CDC)
• U.S. Public Health Service
• World Health Organization (WHO)

Opponents

Opponents of water fluoridation often use one or more of the following arguments:

• Any fluoride above the naturally occurring (usually trace) amounts is unnecessary and possibly toxic.
• An individual dose of fluoride cannot be controlled because it depends on the amount of fluoridated water that a child ingests each day.
• Fluoridation of public water systems deprives people of freedom-of-choice as to what they ingest.
• People can choose from a variety of fluoride-containing products that are just as effective as fluoridated water.
• Where the water is not fluoridated, schools often provide fluoridation programs, and parents can choose whether their children participate.
• Although fluoride may help prevent decay, good diet, good oral hygiene , and regular dental cleanings can be just as effective.
• Fluoride can be toxic and even fatal at higher doses.
• The difference between the amount of fluoride that is beneficial and the amount that can cause mottling is only two to four-fold.
• People vary in their susceptibility to the effects of fluoride.
• It is impossible to determine how much fluoride a child is ingesting because of the numerous sources of fluoride in food and products; a child may regularly drink water from sources with different fluoride levels.
• Fluoride is ineffective against gum disease, the major destroyer of teeth.

Communities throughout the United States, as well as many countries, have chosen not to fluoridate their water. In the early 2000s a number of countries have discontinued fluoridation because of ongoing concerns about possible health effects.

Fluoride dosages

There is some disagreement as to whether fluoride is an essential mineral in humans. Relatively low levels of fluoride (20–80 mg) are considered toxic. Less than 1 gm of fluoride can be fatal to a small child. The Food and Nutrition Board of the Institute of Medicine of the U.S. National Institutes of Health has determined an adequate daily intake of fluoride and a maximal safe daily intake, based on a child's weight:

• infants up to six months of age or about 16 lb (7 kg): 0.01 mg is adequate and 0.7 mg is the maximum safe intake
• infants between six and 12 months or about 20 lb (9 kg): 0.5 mg and 0.9 mg
• children one to three years of age or about 29 lb (13 kg): 0.7 mg and 1.3 mg
• children aged four to seven or about 48 lb (22 kg): 1.0 mg and 2.0 mg
• children aged nine to 13 or about 88 lb (40 kg): 2.0 mg and 10 mg
• children aged 14 to 19 or about 125–166 lb (57–76 kg): 3.0 mg and 10 mg

Fluoride supplements often are prescribed for children who drink nonfluorinated water and do not use fluoride toothpaste. Fluoride supplements should not be used if the drinking water contains more than 0.6 ppm of fluoride. One ppm of fluoride is equivalent to about 1 mg per quart (or liter) of water. Fluoride supplements should not be given to babies under six months of age regardless of the fluoride content of the water. Babies get adequate fluoride from breast milk or infant formula. Powdered or concentrated infant formula should be mixed with low-fluoride or fluoride-free water.

If the water supply contains 0.0 to 0.3 ppm fluoride, the recommended daily dosage of fluoride supplement is:

• 0.25 mg for children aged six months to three years
• 0.50 mg for children aged three to six years
• 1 mg for children aged six to 16 years

If the water supply contains 0.3 to 0.6 ppm fluoride, the recommended daily dosage of fluoride supplement is:

• 0.0 mg for babies aged six months to three years
• 0.25 mg for children aged three to six years
• 0.50 mg for children aged six to 16

Fluoride supplements usually come in the form of sodium fluoride: 2.2 mg of sodium fluoride supplies 1 mg of fluoride ion.

Precautions

A child easily can swallow enough fluoridated toothpaste to exceed the recommended daily amount of fluoride by four-fold. A medium-sized toothpaste tube contains enough fluoride to make a child seriously ill or even cause death should the child eat it all. The flavorings added to toothpaste to encourage children to brush also can entice them into eating it. Toothpaste always should be stored out of the reach of children.

Side effects

As little as four to eight mg of fluoride ingested daily while the tooth enamel is forming can cause mottling—often called fluorosis—in children under age eight. Fluorosis only affects children whose teeth are still developing within the gums. Symptoms of fluorosis include:

• teeth discoloration
• white or brown chalky spots
• brown enamel
• pitting of teeth
• excessive wear on the enamel
• structural damage to the enamel
• brittle teeth in which the enamel breaks easily

The extent of mottling depends on the following:

• when the excess fluoride is ingested
• how much is ingested
• over how long of a period it is ingested
• how much of the fluoride reaches the enamel

Most cases of fluorosis are very mild. Very mild to mild fluorosis has no effect on tooth function and may help prevent decay. Even severe fluorosis is not harmful. Fluorosis in children appears as of 2004 to be increasing; however, it is not known whether this is from water fluoridation, the excessive use of fluoride-containing products, or both.

Prevention

No type of fluoridation can replace good dental care and hygiene, which are necessary for preventing gum disease as well as tooth decay. Weekly rinsing with a fluoride mouthwash can reduce decay in children by 20–40 percent. Fluoride supplements can reduce decay in children by 40 percent, if administered at least 150 days of every year that enamel is forming.

Topical fluoride treatments given in a dentist's office have been proven to be 40 percent or more effective in preventing decay. These treatments include fluoride gels and foams and fluoride varnishes. Advantages of fluoride varnishes include the following:

• They are more concentrated than other fluoride treatments and so are less likely to be ingested.
• They are fast and easy to apply.
• They continue to provide fluoride to the enamel for about 24 hours after application.

Varnishes may be particularly appropriate for young children and those with special needs since varnishes do not require the use of a fluoride tray.

Parental concerns

It is the parents' responsibility to monitor their child's fluoride intake. Pregnant and nursing mothers should pay close attention to how much fluoride they ingest. Children should:

• be over two years of age before using a fluoridated toothpaste; younger children are likely to swallow most of their toothpaste
• use a pea-sized amount of toothpaste or less
• not use fluorinated mouthwashes until the age of six
• be prevented from swallowing fluoridated toothpaste or mouthwash

KEY TERMS

Dentin —The middle layer of a tooth, which makes up most of the tooth's mass.

Enamel —The hard, outermost surface of a tooth.

Fluorapatite —Fluoride-substituted hydroxyapatite.

Fluorosis —Mottled discoloration of tooth enamel due to excessive systemic ingestion of fluoride during tooth development.

Mottling —Fluorosis; spotting on the teeth due to excess fluoride as the tooth enamel is forming.

Plaque —A deposit, usually of fatty material, on the inside wall of a blood vessel. Also refers to a small, round demyelinated area that develops in the brain and spinal cord of an individual with multiple sclerosis.

Remineralization —Recalcification; the process by which minerals from saliva and food are added to the surface of the enamel or to the dentin.

Systemic absorption —Any substance topical, inhaled, or ingested that is absorbed into the blood-stream and distributed throughout the body.

Topical —Not ingested; applied to the outside of the body, for example to the skin, eye, or mouth.

See also Dental development.

Resources

BOOKS

Bailey, K., et al. Fluoride in Drinking Water. London: IWA, 2002.

Bryson, Christopher. The Fluoride Deception. New York: Seven Stories Press, 2004.

PERIODICALS

"Anti-Fluoride Flood." Better Nutrition 65, no. 1 (January 2003): 30–1.

Gorman, Megan Othersen. "Got Enough Fluoride?" Prevention 54, no. 2 (February 2002): 48.

Mascarenhas, Ana Karina. "Risk Factors for Dental Fluorosis: A Review of the Recent Literature." Pediatric Dentistry 22, no. 4 (2000): 269–77.

Motavalli, Jim. "Your Health: Facing up to Fluoride." E: the Environmental Magazine 12, no. 1 (January/February 2001): 40–1.

Pendrys, D. G. "Risk of Enamel Fluorosis in Nonfluoridated and Optimally Fluoridated Populations: Considerations for the Dental Professional." Journal of the American Dental Association 131 (2000): 746–55.

Pratt, Edwin, Jr., et al. "Fluoridation at Fifty: What Have We Learned?" The Journal of Law, Medicine, and Ethics 30, no. 3 (Fall 2002): 117–22.

"Water Fluoridation Debate." Journal of Environmental Health 65, no. 3 (October 2002): 52.

ORGANIZATIONS

American Academy of Pediatric Dentistry. 211 East Chicago Avenue, Suite 700, Chicago, IL 60611–2663. Web site: <www.aapd.org>.

American Dental Association. 211 East Chicago Avenue, Chicago, IL 60611–2678. Web site: <www.ada.org>.

Fluoride Action Network. PO Box 5111, Burlington, VT 05402. Web site: <www.fluoridealert.org>.

National Center for Fluoridation Policy and Research. Department of Oral Biology, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY 14214–3008. Web site: <http://fluoride.oralhealth.org>.

WEB SITES

Connett, Paul. "The Absurdities of Water Fluoridation." Redflagsdaily.com, November 28, 2002. Available online at <www.redflagsweekly.com/connett/2002_nov28.html> (accessed December 27, 2004).

"Fluoride." American Academy of Pediatric Dentistry. Available online at <www.aapd.org/publications/brochures/content/floride.html> (accessed December 27, 2004).

"Oral Health Topics: Fluoride & Fluoridation." American Dental Association. Available online at <www.ada.org/public/topics/fluoride/fluoride_article01.asp> (accessed December 27, 2004).

Margaret Alic, PhD

Fluoridation

Fluoride and tooth decay

Early fluoridation studies

To fluoridate or not to fluoridate

Fluoridation outside the United States

Fluoridation today

Resources

Fluoridation consists of adding fluoride to a substance (often drinking water) to reduce tooth decay. Fluoridation was first introduced into the United States in the 1940s in an attempt to study its effect on the reduction of tooth decay. Since then many cities have added fluoride to their water supply systems. Proponents of fluoridation have claimed that it dramatically reduced tooth decay, which was a serious and widespread problem in the early twentieth century. Opponents of fluoridation have not been entirely convinced of its effectiveness, are concerned by possible side effects, and are disturbed by the moral issues of personal rights that are raised by the addition of a chemical substance to an entire city’s water supply. The decision to fluoridate drinking water has generally rested with local governments and communities and has always been a controversial issue.

Fluoride and tooth decay

Tooth decay occurs when food acids dissolve the protective enamel surrounding each tooth and create a hole, or cavity, in the tooth. These acids are present in food, and can also be formed by acid-producing bacteria that convert sugars into acids. There is overwhelming evidence that fluoride can substantially reduce tooth decay. When ingested into the body, fluoride concentrates in bones and in dental enamel that makes the tooth enamel more resistant to decay. It is also believed that fluoride may inhibit the bacteria that convert sugars into acidic substances that attack the enamel.

Fluoride is the water soluble, ionic form of the element fluorine. It is present in most water supplies at low levels and nearly all food contains traces of fluoride. When water is fluoridated, chemicals that release fluoride are added to the water. In addition to fluoridation of water supplies, toothpaste and mouthwash also contain added fluoride.

Early fluoridation studies

In 1901 Frederick McKay (1874–1959), a dentist in Colorado Springs, Colorado, noticed that many of his patients’ teeth were badly stained. Curious about the cause of this staining, or dental fluorosis as it is also known, McKay concluded after three decades of study that some substance in the city’s water supply caused the discolorations. Analysis of the water indicated high levels of fluoride, and it was concluded that the fluoride was responsible for the stained teeth. McKay also observed that although unsightly, the stained teeth of his patients seemed to be more resistant to decay. The apparent connection between fluoride and reduced decay eventually convinced H. Trendley Dean (1893–1962), of the U.S. Public Health Service (USPHS), to examine the issue more closely.

In the 1930s, Dean studied the water supplies of some 345 U.S. communities and found a low incidence of tooth decay where the fluoride levels in community water systems were high. He also found that staining was very minor at fluoride concentrations less than or equal to one part fluoride per million parts of water (or one ppm). The prospect of reducing tooth decay on a large scale by adding fluoride to community water systems became extremely appealing to many public health officials and dentists. By 1939, a proposal to elevate the fluoride levels to about one ppm by adding it artificially to water supplies was given serious consideration and, eventually, several areas were selected to begin fluoridation trials. By 1950, USPHS administrators endorsed fluoridation throughout the country.

To fluoridate or not to fluoridate

The early fluoridation studies apparently demonstrated that fluoridation was an economical and convenient method to produce a 50–60% reduction in the tooth decay of an entire community and that there were no health risks associated with the increased fluoride consumption. Consequently, many communities quickly moved to fluoridate their water supplies in the 1950s. However strong opposition to fluoridation soon emerged as opponents claimed that the possible side effects of fluoride had been inadequately investigated. It was not surprising that some people were concerned by the addition of fluoride to water since high levels of fluoride ingestion can be lethal. However, it is not unusual for a substance that is lethal at high concentration to be safe at lower levels, as is the case with most vitamins and trace elements.

Opponents of fluoridation were also very concerned on moral grounds because fluoridation represented compulsory mass medication. Individuals had a right to make their own choice in health matters, fluoridation opponents argued, and a community violated these rights when fluoride was added to its water supply. Fluoridation proponents countered such criticism by saying that it was morally wrong not to fluoridate water supplies because this would result in many more people suffering from tooth decay that could have easily been avoided through fluoridation.

The issue of fluoridation had become very much polarized by the 1960s since there was no middle ground: water was either fluoridated or not. Controversy and heated debate surrounded the issue across the country. Critics pointed to the known harmful effects of large doses of fluoride that led to bone damage and to the special risks for people with kidney disease or those who were particularly sensitive to toxic substances. Between the 1950s and 1980s, some scientists suggested that fluoride may have a mutagenic effect (that is, it may be capable of causing human birth defects). Controversial claims that fluoride can cause cancer were also raised. Today, some scientists still argue that the benefits of fluoridation are not without health risks.

Fluoridation outside the United States

The development of the fluoridation issue in the United States was closely observed by other countries. Dental and medical authorities in Australia, Canada, New Zealand, and Ireland endorsed fluoridation, although not without considerable opposition from various groups. Fluoridation in Western Europe was greeted less enthusiastically and scientific opinion in some countries, such as France, Germany, and Denmark, concluded that it was unsafe. Widespread fluoridation in Europe is therefore uncommon.

Fluoridation today

Up until the 1980s the majority of research into the benefits of fluoridation reported substantial reductions (50–60% on average) in the incidence of tooth decay where water supplies had fluoride levels of about one ppm. By the end of the decade however, the extent of this reduction was being viewed more critically. By the 1990s, even some fluoridation proponents suggested that observed tooth decay reduction, directly because of water fluoridation, may only have been at levels of around 25%. Other factors, such as education and better dental hygiene, could also be contributing to the overall reduction in tooth decay levels. Fluoride in food, salt, toothpastes, rinses, and tablets, have undoubtedly contributed to the drastic declines in tooth decay during the twentieth century and, now, in the twenty-first century. It also remains unclear as to what, if any, are the side effects of one ppm levels of fluoride in water ingested over many years.

Although it has been argued that any risks associated with fluoridation are small, these risks may not necessarily be acceptable to everyone. The fact that only about 50% of U.S. communities have elected to adopt fluoridation is indicative of people’s cautious approach to the issue. In 1993, the National Research Council published a report on the health effects of ingested fluoride and attempted to determine if the maximum recommended level of four ppm for fluoride in drinking water should be modified. The report concluded that this level was appropriate but that further research may indicate a need for revision. The report also found inconsistencies in the scientific studies of fluoride toxicity and recommended further research in this area.

Now, early into the twenty-first century, controversy with fluoridation remains strong in the United States and around the world. The American Water Works Association (AWWA), a leading authority on water use, states that the U.S. Public Health Service continues to advise that the optimal level for fluoride in drinking water be in the range of 0.7 to 1.2 milligrams per liter, which is about 0.7 to 1.2 ppm. This optimal level, according to the AWWA, is safe for human consumption and helps to reduce tooth decay. The AWWA also indicates that many public health and professional organizations such as the American Dental Association, the American Medical Association, the U.S. Public Health Service, the

KEY TERMS

Element —A pure substance that can not be changed chemically into a simpler substance.

Fluoridation —The addition to a city’s water supply of chemicals that release fluoride into the water.

Fluoride —The ionic form (negatively charged) of the element fluorine which is soluble in water.

Parts per million (ppm) —A way to express low concentrations of a substance in water. For example, 1 ppm of fluoride means 1 gram of fluoride is dissolved in 1 million grams of water.

Centers for Disease Control and Prevention, and the World Health Organization, are proponents of fluoridation. According to several articles published in the 1990s and 2000s, which stated both sides of the fluoridation issue, opponents of fluoridation represent a minority of the general population and only a small percentage of the scientific community. Most anti-fluoridation organizations are civil, non-profit, or grass-roots organizations.

See also Groundwater; Poisons and toxins; Water conservation.

Resources

BOOKS

Axelsson, Per, DDS. Preventive Materials, Methods, and Programs. Chicago, IL: Quintessence Publishing, 2004.

Liteplo, R. Fluorides. Geneva, Switzerland: World Health Organization, 2002.

Weinstein, Leonard H. Fluorides in the Environment: Effects on Plants and Animals. Wallingford, UK, and Cambridge, MA: CABI Publishing, 2004.

PERIODICALS

Demos, L.L., et al. “Water fluoridation, osteoporosis, fractures: recent developments.” Australian Dental Journal. 46 (2): 80-87 (2001).

Harrison, P.T.C. “Fluoride in water: A UK perspective.” Journal of Fluorine Chemistry. 126 (11-12): 1448-1456 (2005).

Nicholas C. Thomas

Fluoridation

Fluoridation consists of adding fluoride to a substance (often drinking water ) to reduce tooth decay. Fluoridation was first introduced into the United States in the 1940s in an attempt to study its effect on the reduction of tooth decay. Since then many cities have added fluoride to their water supply systems. Proponents of fluoridation have claimed that it dramatically reduced tooth decay, which was a serious and widespread problem in the early twentieth century. Opponents of fluoridation have not been entirely convinced of its effectiveness, are concerned by possible side effects, and are disturbed by the moral issues of personal rights that are raised by the addition of a chemical substance to an entire city's water supply. The decision to fluoridate drinking water has generally rested with local governments and communities and has always been a controversial issue.

Fluoride and tooth decay

Tooth decay occurs when food acids dissolve the protective enamel surrounding each tooth and create a hole, or cavity, in the tooth. These acids are present in food, and can also be formed by acid-producing bacteria that convert sugars into acids. There is overwhelming evidence that fluoride can substantially reduce tooth decay. When ingested into the body, fluoride concentrates in bones and in dental enamel which makes the tooth enamel more resistant to decay. It is also believed that fluoride may inhibit the bacteria that convert sugars into acidic substances that attack the enamel.

Fluoride is the water soluble, ionic form of the element fluorine. It is present in most water supplies at low levels and nearly all food contains traces of fluoride. When water is fluoridated, chemicals that release fluoride are added to the water. In addition to fluoridation of water supplies, toothpaste and mouthwash also contain added fluoride.

Early fluoridation studies

In 1901 Frederick McKay (1874-1959), a dentist in Colorado Springs, Colorado, noticed that many of his patients' teeth were badly stained. Curious about the cause of this staining, or dental fluorosis as it is also known, McKay concluded after three decades of study that the discolorations were caused by some substance in the city's water supply. Analysis of the water indicated high levels of fluoride, and it was concluded that the fluoride was responsible for the stained teeth. McKay also observed that although unsightly, the stained teeth of his patients seemed to be more resistant to decay. The apparent connection between fluoride and reduced decay eventually convinced H. Trendley Dean (1893-1962), of the U.S. Public Health Service (USPHS), to examine the issue more closely.

In the 1930s, Dean studied the water supplies of some 345 U.S. communities and found a low incidence of tooth decay where the fluoride levels in community water systems were high. He also found that staining was very minor at fluoride concentrations less than or equal to one part fluoride per million parts of water (or one ppm). The prospect of reducing tooth decay on a large scale by adding fluoride to community water systems became extremely appealing to many public health officials and dentists. By 1939, a proposal to elevate the fluoride levels to about one ppm by adding it artificially to water supplies was given serious consideration, and eventually several areas were selected to begin fluoridation trials. By 1950, USPHS administrators endorsed fluoridation throughout the country.

To fluoridate or not to fluoridate

The early fluoridation studies apparently demonstrated that fluoridation was an economical and convenient method to produce a 50-60% reduction in the tooth decay of an entire community and that there were no health risks associated with the increased fluoride consumption. Consequently, many communities quickly moved to fluoridate their water supplies in the 1950s. However strong opposition to fluoridation soon emerged as opponents claimed that the possible side effects of fluoride had been inadequately investigated. It was not surprising that some people were concerned by the addition of fluoride to water since high levels of fluoride ingestion can be lethal. However, it is not unusual for a substance that is lethal at high concentration to be safe at lower levels, as is the case with most vitamins and trace elements .

Opponents of fluoridation were also very concerned on moral grounds because fluoridation represented compulsory mass medication. Individuals had a right to make their own choice in health matters, fluoridation opponents argued, and a community violated these rights when fluoride was added to its water supply. Fluoridation proponents countered such criticism by saying that it was morally wrong not to fluoridate water supplies because this would result in many more people suffering from tooth decay which could have easily been avoided through fluoridation.

The issue of fluoridation had become very much polarized by the 1960s since there was no middle ground: water was either fluoridated or not. Controversy and heated debate surrounded the issue across the country. Critics pointed to the known harmful effects of large doses of fluoride that led to bone damage and to the special risks for people with kidney disease or those who were particularly sensitive to toxic substances. Between the 1950s and 1980s, some scientists suggested that fluoride may have a mutagenic effect (that is, it may be capable of causing human birth defects ). Controversial claims that fluoride can cause cancer were also raised. Today, some scientists still argue that the benefits of fluoridation are not without health risks.

Fluoridation outside the United States

The development of the fluoridation issue in the U.S. was closely observed by other countries. Dental and medical authorities in Australia , Canada, New Zealand, and Ireland endorsed fluoridation, although not without considerable opposition from various groups. Fluoridation in Western Europe was greeted less enthusiastically and scientific opinion in some countries, such as France, Germany, and Denmark, concluded that it was unsafe. Widespread fluoridation in Europe is therefore uncommon.

Fluoridation today

Up until the 1980s the majority of research into the benefits of fluoridation reported substantial reductions (50-60% on average) in the incidence of tooth decay where water supplies had fluoride levels of about one ppm. By the end of the decade however, the extent of this reduction was being viewed more critically. By the 1990s, even some fluoridation proponents suggested that observed tooth decay reduction, directly as a result of water fluoridation, may only have been at levels of around 25%. Other factors, such as education and better dental hygiene, could also be contributing to the overall reduction in tooth decay levels. Fluoride in food, salt , toothpastes, rinses, and tablets, have undoubtedly contributed to the drastic declines in tooth decay during the twentieth century. It also remains unclear as to what, if any, are the side effects of one ppm levels of fluoride in water ingested over many years.

Although it has been argued that any risks associated with fluoridation are small, these risks may not necessarily be acceptable to everyone. The fact that only about 50% of U.S. communities have elected to adopt fluoridation is indicative of people's cautious approach to the issue. In 1993, the National Research Council published a report on the health effects of ingested fluoride and attempted to determine if the maximum recommended level of four ppm for fluoride in drinking water should be modified. The report concluded that this level was appropriate but that further research may indicate a need for revision. The report also found inconsistencies in the scientific studies of fluoride toxicity and recommended further research in this area.

See also Groundwater; Poisons and toxins; Water conservation.

Resources

books

Martin, B. Scientific Knowledge in Controversy: The Social Dynamic of the Fluoridation Debate. Albany, New York: State University of New York Press, 1991.

Whitford, G.M. The Metabolism and Toxicity of Fluoride. Basel, New York: Karger, 1989.

periodicals

Hileman, B. "Fluoridation of Water." Chemistry and Engineering News 66 (August 1, 1988): pp. 26-42.

other

National Research Council Committee on Toxicology. Health Effects of Ingested Fluoride. Washington, DC: National Academy Press, 1993.

United States Department of Health and Human Services Committee to Coordinate Environmental Health and Related Programs. Ad Hoc Subcommittee on Fluoride. Review of Fluoride Benefits and Risks: Report of the Ad Hoc Sub-committee on Fluoride. Washington, DC: Public Health Service, Department of Health and Human Services, 1991.

Nicholas C. Thomas

KEY TERMS

Element

—A pure substance that can not be changed chemically into a simpler substance.

Fluoridation

—The addition to a city's water supply of chemicals that release fluoride into the water.

Fluoride

—The ionic form (negatively charged) of the element fluorine which is soluble in water.

Parts per million (ppm)

—A way to express low concentrations of a substance in water. For example, 1 ppm of fluoride means 1 gram of fluoride is dissolved in 1 million grams of water.

Fluoridation

Fluoridation is the precise adjustment of the concentration of the essential trace element fluoride in the public water supply to protect teeth and bones. Advocates of fluoridation such as the American Dental Association (ADA) and the National Center for Chronic Disease Prevention and Health Promotion (CDC) state that fluoridation is a safe and effective method of preventing tooth decay. Opponents of fluoridation however, such as Citizens for Health and the Fluoride Action Metwork, maintain that the role fluoridation in the decline of tooth decay is in serious doubt and that more research is required before placing a compound in water reservoirs that could cause cancer , brittle bones, and neurological problems.

Fluoride is any compound that contains fluorine, a corrosive, greenish-yellow element. Tooth enamel contains small amounts of fluoride. In addition, fluoride is found in varying amounts in water and in all food and beverages, according to the ADA.

A Colorado dentist discovered the effects of fluoride on teeth in the 1900s. When Frederick McKay began practicing in Colorado Springs, he established a connection between a substance in the water and the condition of residents' teeth. People did not have cavities, but their teeth were stained brown. Dental research started on the substance that was identified as fluoride during the 1930s. Researchers concluded that a concentration of fluoride in drinking water at a ratio of 1 part per million (ppm) prevented tooth decay without staining teeth. In 2000, the ADA stated that a fluoride concentration ranging from 0.7 ppm to 1.2 ppm was sufficient to fight tooth decay.

The first community to try fluoridation was Grand Rapids, Michigan. The city fluoridated the community water supply in 1945. Ten years later, Grand Rapids reported that incidents of tooth decay had declined by 60% in the children raised on fluoridated water. During the 1950s, Chicago, Philadelphia, and San Francisco also started to fluoridate their water supply. Cities including New York and Detroit opted for fluoridation during the 1960s. However, not all Americans advocated fluoridation. During the 1950s and 1960s, members of the John Birch Society maintained that fluoridation was a form of mass medication by the government. Some members charged that fluoridation was part of a Communist plot to take over the country. In the decades that followed, fluoridation was no longer associated with conspiracy theories. However, opinion about fluoridation was divided at the close of the twentieth century. By 2000, public water systems served 246.1 million Americans, according to the federal CDC. Of that amount, 65.8% of Americans used fluoridated water.

In Washington D.C., 100% of the water is fluoridated, according to a CDC report on the percentage of state populations with fluoridated public water systems in 2000. The top 10 on the list were: Minnesota (98.2%), Kentucky (96.1%), North Dakota (95.4%), Indiana (95.3%), Tennessee (94.5%), Illinois (93.4%), Virginia (93.4%), Georgia (92.9%), Iowa (91.3%), and South Carolina (91.2%). At the other end of the spectrum in terms of fluoridated public water usage were: Louisiana (53.2%), Mississippi (46%), Idaho (45.4%), New Hampshire (43%), Wyoming (30.3%), California (28.7%), Oregon (22.7%), Montana (22.2%), New Jersey (15.5%), Hawaii (9%), and Utah (2%). The CDC estimated the cost of fluoridation at 50 cents per year in communities of more than 20,000 residents. The annual cost was estimated at $1 in communities of 10,000 to 20,000 residents. In communities numbering less than 5,000 people, the yearly cost was estimated at $3.

The CDC reported in 2000 that extensive research during the previous 50 years proved that fluoridation was safe. Fluoridation was also endorsed by groups including the American Medical Association, the American Academy of Pediatrics, the National PTA, and the American Cancer Society. Advocates of fluoridation state that it especially benefits people who may not be able to afford dental care. Opponents however, counter that toothpaste with fluoride is available for people who believe that fluoride fights tooth decay. Furthermore, opponents point out that toothpaste with fluoride contains a warning label advising users to "seek professional assistance or contact a poison control center" if they accidentally swallow more than the amount used for brushing teeth. Lastly, their question the research methodology used to conclude that fluoridation is responsible for decreased tooth decay. Fluoridation critics include consumer advocates Ralph Nader and Jim Turner. Turner chairs the board of Citizens for Health, a grassroots organization that is asking Congress to hold hearings and review fluoridation policy. Citizens for Health belongs to the groups that believe more research is required to determine the risks and benefits of fluoridation.

[Liz Swain ]

RESOURCES

BOOKS

American Water Works Association. Water Fluoridation Principles and Practices. Denver: AWWA, 1996.

Health Research Staff. Facts You Should Know About Fluoridation. Pomeroy, WA: Health Research Books, 1996.

Martin, Brian. Scientific Knowledge in Controversy: The Social Dynamics of the Fluoridation Debate (Science, Technology and Society). Albany, NY: SUNY Press, 1991.

ORGANIZATIONS

American Dental Association, 211 E. Chicago Avenue, Chicago, IL USA 60611 (312) 440-2500, Fax: (312) 440-2800, Email: [email protected], <http://www.ada.org>

Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA USA 30333 (404) 639-3534, Toll Free: (800) 311-3435, , <http://www.cdc.gov>

Citizens for Health, 5 Thomas Circle, NW, Suite 500, Washington, D.C. USA 20005 (202) 483-1652, Fax: (202) 483-7369, Email: [email protected], <http://www.citizens.org>

National Center for Fluroridation Policy and Research (NCFPR) at the University of Buffalo, 315 Squire Hall, Buffalo, NY USA 14214 (716) 829-2056 , Fax: (716) 833-3517, Email: [email protected], <http://fluoride.oralhealth.org>

Fluoridation

Fluoridation is the process of adding the chemical fluoride to a substance (often drinking water) to reduce tooth decay. In the human body, fluoride acts to prevent tooth decay by strengthening tooth enamel and inhibiting the growth of plaque-forming bacteria. Fluoridation was first introduced into the United States in the 1940s in an attempt to study its effect on the reduction of tooth decay. Since then many cities have added fluoride to their water supply systems.

Early fluoridation studies

In 1901, Frederick McKay (1874–1959), a dentist in Colorado Springs, Colorado, noticed that many of his patients had brown stains, called mottled enamel, on their teeth. After studying the cause of this staining for three decades, McKay concluded that it was due to high concentrations of fluoride in the patients' drinking water. McKay also observed that although unsightly, the stained teeth of his patients seemed to be more resistant to decay. After experimentation, he found that the ideal level of fluoride in water should be one part fluoride per million parts of water (or one ppm). That was enough to stop decay but too little to cause mottling.

The U.S. Public Health Service (USPHS) grew interested in fluoride and, following safety tests on animals, conducted field tests. In 1945, the public water systems of Newburgh, New York, and Grand Rapids, Michigan, became the first ever to be artificially fluoridated with sodium fluoride.

Results of these tests seemed to show that fluoridation reduced dental cavities by as much as two-thirds. Based on those results, the USPHS recommended in 1950 the fluoridation of all public water systems in the United States. Later that year, the American Dental Association added its endorsement, and the American Medical Association followed suit in 1951.

To fluoridate or not to fluoridate

Even though almost the entire dental, medical, and public health establishment favored fluoridation, the recommendation was immediately controversial, and has remained so. Opponents objected to fluoridation because of possible health risks (fluoride is toxic, or poisonous, in large amounts). They also objected to being deprived of the choice whether to consume a chemical. Despite the opposition, nearly 60 percent of people in the United States now drink fluoridated water. Fluoridation also is practiced in about 30 other countries.

Fluoridation today

Over the years, other ways of applying fluoride have been developed. In 1956, Procter & Gamble added fluoride to one of its brands of toothpaste, Crest. Four years later, the Council on Dental Therapeutics of the ADA gave Crest its seal of approval as "an effective decay-preventive dentifrice." The ADA now estimates that brushing with fluoride-containing toothpaste reduces tooth decay by as much as 20 to 30 percent.

By the 1990s, the initial claims that fluoridation in drinking water produced two-thirds less tooth decay had been modified to about 20 to 25 percent reduction. Researchers now believe that the overall reduction of tooth decay levels in the twentieth century has been brought about by the addition of fluoride to many items, including food, salt, toothpaste, and mouth rinses. Education and better dental hygiene also have played a part. In 1993, the National Research Council published a report stating the maximum recommended level of four ppm for fluoride in drinking water was appropriate. Since then, the scientific debate of the health benefits of fluoridation versus its possible health risks has continued. Both sides agree that further research into this area is needed.

Words to Know

Fluoride: A form of the element fluorine that is soluble in water. It is often added to drinking water to reduce tooth decay.

Parts per million (ppm): A way to express low concentrations of a substance in water. For example, 1 ppm of fluoride means 1 gram of fluoride is dissolved in 1 million grams of water.

[See also Poisons and toxins ]