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  Wikipedia: Fluoride

Wikipedia: Fluoride
Fluoride
From Wikipedia, the free encyclopedia.

A fluoride is a binary compound of fluorine with another element or radical. Examples of common fluoride compounds include hydrofluoric acid (HF), and sodium fluoride (NaF).

Uses

Fluoride compounds are used in a wide range of applications.

Where instead used in very low concentrations (on the order of parts per million), fluorides are used in human health applications; specifically, fluorides such as sodium fluoride (NaF), sodium monofluorophosphate (SMFP), stannous fluoride (SnFF2), and amine fluoride are common ingredients in toothpaste. Many dentists also give their patients semiannual fluoride treatments.

Similarly, many North American municipalities also fluoridate their water supplies, citing effectiveness in reducing tooth decay, safety of fluoridation, and the low cost to do so. The American Dental Association, World Health Organization, and some other health organizations recommend fluoridation of municipal water supplies to a level between 0.7 and 1.2 ppm.

When used in very high concentrations (on the order of 10% by volume or higher) , sodium fluoride may be found in rat poisons, insecticides, and wood preservatives.

Fluorides and human health

High concentrations

In high concentrations, as with almost all substances, fluoride compounds are toxic. 5 grams of full strength sodium fluoride will kill most adult humans; a lethal dose is approximately 75mg per kilogram body mass. When ingested directly, fluoride compounds are readily absorbed by the intestines; over time, the compound is excreted through the urine, and the half life for concentration of fluorine compounds is on an order of hours. Implied is that fluoride is taken out of circulation by the body and trace amounts bound in bone. Urine tests are a good indication of high exposure to fluoride compounds in the recent past.

In 1973 Jason Burton, a boy in Melbourne, Australia died after swallowing six fluoride tablets; four were recovered after a stomach pumping while the other two had already been absorbed into the body. The hospital staff had assumed it would take well over 100 tablets to be fatal, making the Burton case an object lesson in high concentration fluoride intake.[1]

High concentration salts of fluorine are toxic if swallowed or inhaled. In October 1948 Donora, Pennsylvania had an incident of fluoride poisoning as a result of a temperature inversion in a valley of zinc and steel works; 20 died.[1]

Contact by many fluoride compounds (in high concentrations) with skin or eyes is dangerous. In case of accidental swallowing, give milk, calcium carbonate or milk of magnesia to slow absorption. Eye or skin contact should be treated by removing any contaminated clothing and flushing with water.

Low concentrations

Fluoride is best known for its use in small quantities to help reduce cavity frequency in teeth. A debate continues about whether fluoride ions (F-) are a trace element beneficial to humans for other reasons. Health Canada's current stance is that fluorides are beneficial to teeth, but that other physiological benefits are unproven.[[1] p3]. The National Academy of Sciences generally agrees with Health Canada's opinion; from a November 1998 letter: "First, let us reassure you with regard to one concern. Nowhere in the report is it stated that fluoride is an essential nutrient. If any speaker or panel member at the September 23rd workshop referred to fluoride as such, they misspoke. As was stated in Recommended Dietary Allowances 10th Edition, which we published in 1989: 'These contradictory results do not justify a classification of fluoride as an essential element, according to accepted standards. Nonetheless, because of its valuable effects on dental health, fluoride is a beneficial element for humans.'"[1]

Fluoride compounds, usually calcium fluoride, are naturally found in low concentration in drinking water and some foods, like tea. Fluoride ions replace Hydroxide ions in Calciumhydroxyapatite Ca5[(PO4)3OH] in teeth, forming Calciumfluoroapatite, Ca5[(PO4)3F] which is more chemically stable and dissolves at a pH of 4.5, compared to 5.5 pH for Calciumhydroxyapatite. This is generally believed to lead to fewer cavities, since stronger acids are needed to attack the tooth enamel.

The only generally accepted adverse effect of low concentration fluoridation at this time is fluorosis. It is a condition caused by 'excessive' intake of fluorine compounds over an extended period of time, and can cause yellowing of teeth, or brittling of bones and teeth. The definition of 'excessive' in the context of fluorosis falls on the order of parts per million and is generally accepted to mean significantly higher than the 0.7 to 1.2 ppm amounts the American Dental Association recommends for fluoridated water. One brand of popular bottled water was tested by a critic of the practice of fluoridation to have 3.6 ppm of fluoride; this is a good example.[1]

Fluoride was also tried as a therapy for osteoporosis (on an order of 75mg/day, a relatively high dose). Bone density did increase in the studies. However, some in the study had to reduce their fluoride dosage to avoid side effects. Additionally, overall bone strength was compromised. The treatment created a coarse crystalline matrix with reduced tensile strength, which made the bone (especially the cranked hip joint) susceptible to failure in bending.[1]

The fluoridation debate

Possible side effects of low concentration intake

Some scientific studies suggest that the use of fluorides, particularly silicofluorides (H2SiF6 and Na2SiF6), when over 2 ppm in water, has been implicated as a possible contributing factor in many cases of fetal damage, dental fluorosis, weakened bones and Alzheimer's Disease. [1] [1] Note that 2ppm is significantly higher than the American Dental Association's recommendation of 0.7 - 1.2 ppm in water supplies.

Even tiny amounts may have side effects. Florida International University found that peripheral-vision response delay increased by 0.5 seconds with just 0.5 mg of sodium fluoride - about as much fluoride as would be in a pint of "optimally" fluoridated water.

Another study states that water fluoridation done with silicofluorides (as opposed to sodium fluoride, which does not show this effect) may cause higher lead absorption levels in children[1].

At least four separate large-scale studies totalling nearly half a million persons showed no net reduction in caries by fluoridation; other studies have shown the decline in caries has been occurring at statistically the same rate in fluoridated and unfluoridated areas.[1] [1] [1] This is in contradiction to the great majority of studies and reviews on this subject. A few examples: [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1]

A large majority of epidemiological studies of fluoridation have found no adverse health effects. Critics point out these studies are often funded by institutions with an interest in continuing fluoridation and, they say, that researchers such as Phyllis Mullenix have been fired for coming up with "fluoride is harmful" results. However Dr. Charles Vorhees, editor-in-chief of the journal Neurotoxicology and Teratology said of Mullenix, "Nobody else could ever produce (results) consistent with Phyllis'" even though non-US researchers have done so, including finding the effect in humans.[1] Critics also contend that others, such as William Marcus (reinstated with back pay and interest in 1992 by a court order, the judge noting "the reasons given for Dr. Marcus' firing were a pretext…his employment was terminated because he publicly questioned and opposed EPA's fluoride policy.") and John Colquhoun, have been fired for poking holes in attempts to show fluoride is safe. They go on to say that this discourages objectivity and that studies have been repeatedly shown to have flawed techniques or to have misrepresented or massaged their data.[1] [1]

Industrial conspiracy

Critics of fluoridation charge that fluoride is deliberately associated with good health to protect many major industries, especially uranium, aluminum, and steel smelting, from the massive lawsuits that began to be filed in the 1930s for fluoride related damage to livestock, farms, and community health. One noted critic, Dr. Robert Carton of the US EPA said "Fluoridation is the greatest case of scientific fraud of this century, if not of all time." (Marketplace CBC 1992 Nov 24). The EPA's scientists continue to wrangle with their employer over its fluoride policies.[]

It is, however, true that the volte-faces on fluoridation by the ADA, AMA, and PHS occurred coïncidentally with the heading of the FSA by Oscar Ewing, a highly-paid lawyer for Alcoa. Alcoa had been connected to fluoride study since the discovery of fluorosis in the town of Bauxite, Arkansas as part of the "brown stain" mystery.[1]

Court cases

The issue of fluoridation has been the basis for many court cases. Anti-fluoride activists have sued cities for infringing upon their rights, and on the claim that fluoridation is a form of involuntary medication.[1] Individuals have sued cities for a number of illnesses that they blamed on fluoridation of the city's water supply. In general courts have found in favour of cities in such cases and have not found a connection between health problems and fluoride.

Cities and countries' choices on fluoridation

A 1998 ADA study asked the question Do you believe community water should be fluoridated? 70% said 'yes', and 18% said 'no', with the rest undecided. Health organizations and dentists that recommend water fluoridation point to the great majority of studies which show statistically significant decreases in cavities where water fluoridation is done. A handful of other studies show no reduction or even increases in cavities.

The idea to fluoridate public water supplies goes back to study of "Colorado brown stain", a condition of the first settlers wherein their teeth were severely stained, sometimes chocolate colored. This was eventually identified as severe fluorosis. Unusual resistance to dental decay was also noted. This was attributed to the fluorine content of the water;[1] the water also had high calcium and magnesium content which was apparently overlooked.[1]

Fluoridation was first introduced in the late 1940s. Debates began in many communities; ultimately, most decided to accept fluoridation. The first city to fluoridate its water was Grand Rapids, Michigan in 1945, as part of a ten year evaluation of fluoridation. (The experiment was effectively terminated early, in 1951, with the imposition of fluoridation in the control group, Muskegon, Michigan.[1])

Unlike North America, less than 2% of Europe's population has fluoridated water. Sweden banned fluoridation in 1971 by mandate of their Supreme Court; Holland banned it constitutionally in 1976. West Germany rejected it in 1971; Norway, 1975; Denmark, 1977; France, 1980. In other places in the world, Chile rejected fluoridation in 1977; India and Egypt also have. Finland maintains an "experimental program" covering only 1½% of its people.[1] In Switzerland, only Basel's water was fluoridated, and that was stopped in April 2003 on the advice of their Health and Social Commission.class="external">[1 Diesendorf "Mystery of Declining Tooth Decay" Nature 1986 points out "in western Europe where there is little fluoridation...large reductions in caries had been occurring in unfluoridated areas."—emphasis added)

In the United States, 45 cities abandoned the practice between 1990 and 1996. Gov. Pataki of New York signed on July 2, 1996 a law transferring the decision to fluoridate water from bureaucrats to elected officials.[1])

In Canada, Calgary began fluoridating in 1991 after the fifth plebicite on the prospect finally approved it in 1989--although a 1984 study showed that fluoridated Edmonton had a statistically identical rate of tooth decay. Whitehorse, watching Calgary review the decision in 1998, ended its 30 years of fluoridation.[1]

Secondary effects of fluoridation

In 1970, Grand Rapids, Michigan and Newburgh, New York had twice the United States average of dentists per capita (Anne-Lise Gotzsche The Fluoride Question, Panacea or Poison? p8). The ADA found in 1972 that dentists make 17% more profit in fluoridated areas as opposed to non-fluoridated areas (Douglas et al. "Impact of water fluoridation on dental practices and dental manpower" Journal of the American Dental Association 84:355-67, 1972). This could simply be a correlation between cities with fluoridated water having larger populations to serve, on the assumption that larger cities or water supplies are more likely to fluoridate their water. <someone should check that Gotzsche and ADA compared equivalent water supplies>

Conclusion on controversy

There are numerous studies dealing with water fluoridation. Most show that water fluoridation reduces cavities with no significant risk of other effects, when done at prescribed levels (this is what most North American communities accept as scientific fact). Some show a statistically significant increase in fluorosis when fluoridation is done (even while cavities are decreased). Still others show fluoridation providing no benefits at all.

An overriding concern with any fluoridation study, pro or against, is that the scientific method, and direct causation is established that cannot be otherwise explained.

In any event, the controversy over fluoridation's effects (positive or negative) on the public health is unlikely to end soon.

See also, Dr. Strangelove, a movie in which a character goes insane and believes that water flouridation is a conspiracy.

External Links

Pro fluoridation

Anti fluoridation

Research sites


  

From Wikipedia, the free encyclopedia. 
Modified by Geona