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What are the uses of Water Fluoride ?
Fluorine is a member of the halogen
family. The ionic form of fluorine is the fluoride ion. Thus
they can be defined as the organic and inorganic elements
containing fluorine. Few examples of common fluoride compounds
include hydrofluoric acid (HF), sodium fluoride (NaF), calcium
fluoride (CaF2), oxygen difluoride (OF2). Fluorides are
generally colorless and to a great extent water soluble.
They are present in the following
forms
• In air in the form of gases
• In water as fluoride ions
• In soils with calcium and aluminum
• In living beings
Fluorides are used for a variety of commercial purposes
including fluoridation of drinking water, and aluminium
production. Fluoride is particularly helpful in strengthening
the tooth enamel if taken in optimal amounts. Hence sodium
fluoride and sodium monofluorophosphate are usually added to
water in oral hygiene products like the toothpaste. Research has
shown that 0.7 to 1.5 milligrams of fluoride in drinking water
prevents tooth decay and also helps in bone and tooth
development. The American Dental Association has affirmed that
fluoride is beneficial for people of all ages. In young children
(whose teeth are in the process of formation), fluoride hardens
the tooth enamel. People who consume fluoridated water from
their childhood can prevent tooth decay to a great extent.
Fluoride also helps in combating tooth decay much before it is
detectable- a process known as re-mineralization.
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One of the key sources of fluoride
consumption is water. Since it exists in all forms in nature, it
dissolves in water when the latter passes through rocks and
various other particles. Thus small quantities of fluoride are
present in almost all the water sources. Many countries add an
optimum amount of fluoride (less than 4 ppm) to the public water
supplies, a process that is termed as fluoridation. Fluoridation
of drinking water can be controversial. Opponents argue
fluoridation violates individual rights and goes against
religious beliefs that ban medication. The courts have
established fluoridation is not an unconstitutional invasion of
religious freedom or other individual rights. It has been the
position of courts that a significant government interest in
health and welfare of the public generally overrides individual
objections to public health regulation. Historically,
populations benefiting from fluoridated drinking water have
developed fewer cavities. |
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Opponents also argue that drinking
fluoridated water promotes a variety of physical and mental
ailments including sickle-cell anemia, cancer, cardiovascular
disease, AIDS, Down Syndrome and Alzheimer's disease. Since the
1930's, many scientific studies have shown that water
fluoridation, at the concentrations recommended for good oral
health, has no harmful effects. However, an excess intake of
fluoride is harmful for health and causes fluorosis. It can also
lead to severe toxicity resulting in vomiting and nausea. So in
such cases of accidental consumption of large amount of
fluoride, one needs to rush for medical attention. Skeletal
fluorosis is another result of excessive fluoride accumulation
in our body. The symptoms are intermittent pains and cramping of
the joints, muscle weakness, stomach ache and head ache. This
can lead to the deformations of the bones. Unfortunately, till
date there has been no treatment of fluorosis, thus the best way
to prevent it is to keep the fluoride intake minimal.
There are multiple industrial usages of fluoride in various
forms. Hydrofluoric acid (HF) is used industrial applications
like integrated circuit manufacturing. It is also used
extensively in the etching of glass. Fluoride containing
compounds are added to toothpaste, drinking water, prescribed
treatments, and other commercially available oral hygiene
products because fluoride proponents believe they help
strengthen the tooth enamel. Sodium fluoride and sodium
monofluorophosphate (MFP, SMFP) are the common additives. Many
local water municipalities fluoridate their water supplies by
adding fluoride in concentrations of less than 4 ppm.
Originally, sodium fluoride was used to fluoridate water;
however, hexafluorosilicic acid (H2SiF6) and its salt (Na2SiF6)
are more commonly used. Fluoride ion has a very significant use
in synthetic organic chemistry. The silicon-fluorine chemical
bond is quite strong. Silyl ether protecting groups can be
easily removed by the addition of fluoride ion. Sodium fluoride
or tetra-n-butyl ammonium fluoride (TBAF) are the most common
reagents used.
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In surface waters, such as rivers,
fluoride levels depend on the proximity to natural emission
sources; they generally range from 0.01 to 0.3 mg/liter. In
seawater fluoride concentrations are higher, i.e. 1.2 to 1.5
mg/liter. In areas where the natural rock is rich in fluoride or
where there is geothermal or volcanic activity, very high
fluoride levels, up to 50 mg/liter, may be found in groundwater
or hot springs.
In air, fluoride emitted both naturally and from human
activities in gaseous and particulate forms generally deposits
relatively near its emission source. In areas without nearby
emission sources, the mean concentrations of fluoride in ambient
air are generally less than 0.1 µg/m3. Even near emission
sources, the levels of airborne fluoride usually do not exceed
2–3 µg/m3.
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In most soils, fluoride is present at
concentrations ranging from 20 to 1000 µg/g. This figure can reach
several thousand µg/g in mineral soils with natural phosphate or
fluoride deposits. Aquatic organisms take up fluorides directly from
water and to a lesser extent via food, and tend to accumulate
fluoride in their exoskeleton or bone tissue. In the exoskeleton of
krill the mean fluoride concentrations have been measured to be more
than 2000 mg/kg while mean bone fluoride concentrations in aquatic
mammals, such as seals and whales, ranged from 135 to 18 600 mg/kg
dry weight.
Fluoride levels in terrestrial animals and plants are higher near
natural and human fluoride emission sources. Lichens, which have
been used extensively as bio-monitors for fluorides, generally
contain less than 1 mg fluoride/kg (background level), but at a
distance of 2 to 3 km from fluoride emission sources mean
concentrations range from 150 to 250 mg/kg. Most of the fluoride in
the soil is insoluble and, therefore, less available to plants. But
the fluoride that is present in soil solution is taken up through
the root and accumulates in leaves. Fluoride accumulates in the bone
tissue of terrestrial vertebrates, depending on factors such as diet
and the proximity of fluoride emission sources. For example, mean
fluoride concentrations of 7000 to 8000 mg/kg have been measured in
the bones of small mammals living near an aluminum smelter. |
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Article Contributed By: Sukanaya Banerjee
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