Fluoridation Additives: FAQs
What additives are used to fluoridate water?
Fluorosilicic acid is the most commonly used
additive for water
fluoridation, followed by two dry additives—sodium fluorosilicate and
sodium fluoride. Fluorosilicic acid is derived from production of
phosphate fertilizers. The apatite ore (a type of limestone) is mixed
and heated with sulfuric acid to form a phosphoric acid-gypsum slurry,
the starting point to make pelletized phosphate fertilizers. The
hydrogen fluoride and silicon tetrafluoride that would otherwise be
released to the atmosphere or left in the gypsum slurry is deliberately
recovered from the slurry by evaporators and condensed to fluorosilicic
acid that can be used for the water fluoridation process. Both sodium
fluorosilicate and sodium fluoride are created by neutralizing
fluorosilicic acid with either sodium chloride (table salt) or caustic
soda.
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Is fluorosilicic acid the residue
of the production of pesticides, rodenticides or the nuclear industry?
No. It is a valuable
co-product derived from the
production of fertilizer. It is not derived from pesticide, rodenticide
or nuclear power production.
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Do these additives have to meet standards for quality and purity?
The American Water Works Association (AWWA) prepares
standards for
the manufacturing, quality, and verification of the fluoride additives.
The American National Standards Institute prepares standards which covers impurities of
drinking water treatment additives from their production and
distribution to user and includes documentation of the purity of
additives. Verification testing by independent certification entities
including NSF International and Underwriters Laboratories (UL) documents that the
actual purity exceeds the standards. The NSF/ANSI (National Sanitation
Foundation/American National Standards Institute) standard 60
and 61 were developed by a consortium of associations, including NSF
International, AWWA,
the American National Standards Institute (ANSI), the Association of
State Drinking Water Administrators, and the Conference of State Health
and Environmental Managers.
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Who establishes
standards for the chemicals used
to fluoridate water?
The American Water Works Association (AWWA) prepares standards for
the manufacturing, quality, and verification of the fluoride
additives. The NSF/ANSI (National Sanitation Foundation/American
National Standards Institute) prepares standards which covers
impurities of drinking water treatment additives from their production
and distribution to user and includes documentation of the purity of
additives. A key concept is that an additive should not add more than
10 percent of the MCL (Maximum Contaminant Level) of any regulated
drinking water substance in order to ensure the protection of the
public. independent certification entities including NSF
International and Underwriters Laboratories (UL) documents that the
actual purity exceeds the standards. The NSF/ANSI standard 60
and 61 were developed by a consortium of associations, including NSF
International, AWWA, the American National Standards Institute (ANSI),
the Association of
State Drinking Water Administrators, and the Conference of State
Health and Environmental Managers.
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What is the cost of installing fluoridation equipment
for communities?
The cost of installing fluoridation addition equipment for a
community water system varies from approximately $5 to $20 per person,
depending on a number of factors. Each system would need to have an
engineer review the requirements for an individual location to estimate
its specific costs. Larger systems serving more customers are typically
the most inexpensive and cost effective to manage. In fact, an
economic analysis found that for
larger communities of more than 20,000 people where it costs about 50
cents per person to fluoridate the water, every $1 invested in this
preventive measure yields $38 savings in dental treatment costs.
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How can I find out the fluoride concentration of
my drinking water?
All public water systems are required by the
Environmental Protection Agency to publish an annual Consumer Confidence
Report that will include numerous facts about your drinking water,
including the fluoride level. If you are on a public water system, you
can call the water utility company and request a copy of the utility's
most recent Consumer Confidence Report. If you live in a state that
participates in CDC's
My Water's Fluoride, you can go online and find
information on your water system's fluoridation status. If you have a
home well, you will need to have a sample of your water analyzed by a
laboratory. Your dentist, physician, or public health department should
be able to help you get your water analyzed. Whether on well or public
water supply, if you have water fluoride levels under 0.6 ppm, your
child's dentist or pediatrician should evaluate whether your child can
benefit from daily fluoride supplements. Their recommendation will
depend on your child's risk of developing tooth decay and as well as
exposure to other sources of fluoride (e.g., drinking water at school or
daycare, toothpaste).
If the natural fluoride level of your well or
community drinking water is greater than 2 ppm, you should consider an
alternate source of drinking water for any child 8 years and younger. Their teeth are still developing and will be at risk for
dental fluorosis.
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My home gets its water from a well. Can I add
fluoride to my well water?
Many groundwaters have naturally occurring fluoride content. If there
is less than 0.6 ppm of fluoride in your well water, it is considered
sub-optimal for preventing tooth decay. It is not feasible to add
fluoride for an individual residence’s well. You should have your home
well water tested for its fluoride content by a laboratory. Check with
your dentist, physician or public health department to learn how to have
your home well water tested. Additional information on testing well
water quality in private wells serving homes can be found on the
U.S.
Environmental Protection Agency Web site. See above question for
more information.
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Will using a home water filtration system take the
fluoride out of my home’s water?
Removal of fluoride from water is a difficult water
treatment action. Most point-of-use treatment systems for homes that
are installed for use by single faucets use activated carbon
filtration, which will not remove the fluoride ion. The ability of
other treatment systems such as reverse osmosis, ion exchange, or
distillation systems to reduce fluoride levels vary in their
effectiveness to reduce fluoride. Check with the manufacturer of the
individual product.
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Will boiling or freezing reduce the fluoride
level in water?
Fluoride is not released from water when it is boiled or
frozen. One exception would be a water distillation system. These systems
heat water to the boiling point and then collect water vapor as it
evaporates. Water distillation systems are typically used in laboratory
installations. For home use these systems can be expensive and may present
safety and maintenance concerns.
If you are concerned about the fluoride level in your
home water (above the level of 2 parts per million), you should use water
from a commercial bottler whose water has the level of fluoride you desire.
The optimal level of fluoride in drinking water for the prevention of tooth
decay is 0.7 ppm to 1.2 ppm.
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Will water fluoridation result in pipe
corrosion or increased lead in drinking water?
Water fluoridation will not increase water
corrosion or cause lead to leach (dissolve) from pipes and household plumbing fixtures.
Although lead in public drinking water is typically found to be very low or
is below
laboratory detection, there are locations where old lead pipes, solder,
or plumbing fixtures in old homes may experience leaching of lead into
water. This is principally a problem in some older homes because newer homes
have been constructed in accordance with new plumbing standards that
prohibit the use of lead in plumbing pipes and fixtures. Ask your local
water utility system if there have been problems with higher lead levels in
water from older homes in your community. Claims by some that fluoride
might result in increased lead leaching from pipes and fixtures has not
been substantiated in the peer-reviewed literature.
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Date last reviewed: August 24, 2009
Date last updated: November 17, 2010
Content source:
Division of Oral Health,
National Center for Chronic Disease Prevention and
Health Promotion |
