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Context - Food and drinking water typically contain at least small amounts of fluorides. They occur in the environment both naturally and as a result of human activities.
Fluorides are commonly added to dental products – and sometimes to tap water – to prevent cavities.
Under what conditions can fluoride exposure be beneficial or detrimental to human health?
Latest update: 15 April 2005
1. What are fluorides?
organic and inorganic
compounds containing the fluorine
element. Only inorganic fluorides
are the focus of this study, particularly those which are most present
in the environment and may affect living organisms.
Generally colourless, the different fluoride
compounds are more or less
soluble in water and can take the
form of a solid, liquid, or gas.
Fluorides are important industrial
chemicals with a number of uses but the largest uses are for aluminium
production, drinking water fluoridation, and the manufacture of
fluoridated dental preparations.
2. Where are fluorides found?
In the environment, fluorides
occur both naturally (e.g., rock weathering, volcanic emissions) and
because of human activities (e.g., phosphate rock mining and use,
aluminium manufacturing, drinking water fluoridation).
Fluorides can be present:
- in air, as gases or particulates;
- in water, mostly as fluoride
ions or combined with aluminium;
- in soils, mainly combined with calcium or aluminium; and
- in living organisms.
Fluoride levels in the
environment depend on the proximity to both natural and human fluoride
fluoride in their skeleton and
plants in their leaves.
3. How are humans exposed to fluorides?
fluoride can either be naturally
present due to the specific geological environment from which the water
is obtained, or artificially added for the prevention of
contain at least small amounts of
fluoride, but in some the
concentrations can be higher.
Fluoride concentration in food can
be increased by the presence of fluoride in water used for its
Source: Micro Application
such as toothpaste, fluoride is
present in significant amounts.
The consumption of foodstuffs and drinking water is the principal
route of exposure to
fluoride for adults, while the
ingestion of toothpaste by young
children makes a significant contribution to their total
intake of fluoride.
Humans retain 60 to 90% of the
fluoride taken in and
accumulate almost all of it in
their bones and teeth.
4. Can fluorides affect health?
Various harmful effects were observed in a series of animal laboratory
studies, such as effects on the formation and hardening of
bones, and delayed fracture
Animal laboratory studies did not conclude that
fluoride increases the frequency of
Fluoride does not cause
mutations but it has been shown to
cause damage to chromosomes at high
doses in studies in
cell cultures. This has not been
shown in most studies on test animals fed with fluoride.
Drinking water containing
fluoride has not affected
reproduction or development of the foetus in most studies on test
animals. Microscopic changes in reproductive organs have been seen at
high doses in some studies.
6. To what extent can fluoride exposure be harmful to organisms in the environment?
Different organisms living in water are more or less sensitive to
fluoride. It can affect their
growth, activity, or survival above certain
In plants, high levels of
fluoride can lead to the yellowing
of leaves and slowed growth, as shown by studies where fluoride was
deposited on leaves.
In birds, laboratory tests showed high levels of
fluoride could affect chick growth
or survival. In deer, cattle, and sheep it was observed that high
fluoride intake affected weight,
joints, teeth, and bones, milk
production and reproduction.
7. What are the risks posed by fluorides?
The most serious effect of
fluoride is its
bones from long-term excessive
exposure, which can lead to
skeletal fluorosis and
Fluoride discharges from human
activities can be toxic to aquatic
organisms and pose a risk to local
sensitive plant species on land.
High fluoride content in plants near emission sources or due to
fertilizer use is a potential risk to animals that eat them.
8. What are the beneficial effects of fluoride on teeth?
Oral fluoride is considered as an effective means of reducing dental
© Micro Application
An "optimum" level of fluoride
in drinking water, associated with the maximum level of
dental caries protection and
minimum level of dental fluorosis,
has been determined.
benefiting from fluoridated drinking water have developed fewer
cavities. Today, many other
fluoridated products are more extensively used and contribute to
protecting a wider population.
There is a variety of fluoridated products: fluoridated drinking
water, toothpaste, mouth solutions, gels or varnishes, salt, milk, and
9. Does water fluoridation pose risks?
The intake of excessive amounts of
fluoride can lead to
dental fluorosis, preventing the
normal maturation of the enamel,
but only during the period of tooth development in children, up to 6–8
The increase in the frequency of
dental fluorosis over the past 30
to 40 years is generally attributed to the widespread use of
fluoride products other than
drinking water. Dental fluorosis is common in certain areas of the
world, such as China, where fluoride is naturally present at high levels
in minerals and water.
The greater the amount of
fluoride incorporated into
bone, the more severe the
effects on bones.
In certain areas of the world where high levels of
fluoride are naturally present,
skeletal fluorosis is widespread,
mainly due to an increased intake of
fluoride from foodstuffs and drinking water. However, other factors,
such as nutrition and climate, may also be important.
Fluoride can help prevent
cavities, but at high
intakes it can harm tooth development
(dental fluorosis) and
(skeletal fluorosis); there is a
narrow range between intakes which are beneficial and those which are
detrimental. Populations consuming
artificially fluoridated drinking water or other fluoridated products,
such as fluoridated toothpaste, develop fewer cavities.
In areas of the world with high levels of
fluoride naturally present in
minerals and water,
skeletal fluorosis is common. This
crippling disability, which includes increased
bone fracture, affects millions of
people in various parts of Africa, China and India.
All organisms both on land and in water are
fluoride released from natural
sources and/or by human activities. Excess
exposure poses a
risk to them.
There is a need to better characterize the biological effects of
exposure to different levels of