According to the Centers for Disease Control and Prevention (CDC), the proper
amount of fluoride from infancy through old age helps prevent and control tooth
decay. In a minority of children, fluoride exposure during the ages when teeth
are forming (from birth through age 8) also can result in a range of changes
within the outer surface of the tooth called enamel fluorosis. Recent evidence
suggests that mixing powdered or liquid infant formula concentrate with
fluoridated water on a regular basis may increase the chance of a child
developing the faint white markings of very mild or mild enamel fluorosis. This
occurs on baby and permanent teeth while they are forming under the gums. Once
the teeth come into the mouth, they are no longer able to develop this
condition.  Typically, very mild or mild fluorosis is barely noticeable,
if noticed at all. Studies have not shown that teeth are likely to develop more
esthetically noticeable forms of fluorosis, even with regular mixing of formula
with fluoridated water.

The possibility of
an association between fluoride in infant formula and the risk for enamel
fluorosis has been studied for many years. Until now, most researchers
concluded that fluoride intake during a child's first 10 to12 months had little
impact on the development of this condition in permanent teeth. A recent study,
however, has raised the possibility that fluoride exposure during the first
year of life may play a more important role on fluorosis development than was
previously understood. It now appears that the amount of the fluoride contained
in the water used for mixing infant formula may influence a child’s risk for
developing enamel fluorosis, particularly if the child’s sole source of
nutrition is from reconstituted infant formula.

Here are the CDC’s
recommendations for infant formula and enamel fluorosis:

What is the best
source of nutrition for infants?

Breastfeeding
is ideal for infants. CDC is committed to increasing breastfeeding rates
throughout the United States and to promoting optimal breastfeeding practices.
Both babies and mothers gain many benefits from breastfeeding. Breast milk is
easy to digest and contains antibodies that can protect infants from bacterial
and viral infections. 
If breastfeeding is not possible, several types of
formula are available for infant feeding. Parents and caregivers are encouraged
to speak with their pediatrician about which type of infant formula is best
suited for their child.

What type of water
does CDC recommend for mixing infant formula?

Parents
should follow the advice of the formula manufacturer and their child’s doctor
for the type of water appropriate for the formula they are using. Parents and
caregivers of infants fed primarily with formula from concentrate who are
concerned about the effect that mixing their infant’s formula with fluoridated
water may have in developing enamel fluorosis can lessen this exposure by
mixing formula with low fluoride water most or all of the time. This may be tap
water, if the public water system is not fluoridated (check with your local
water utility). If tap water is fluoridated or has substantial natural fluoride
(0.7 mg/L or higher), a parent may consider using a low-fluoride alternative
water source. Bottled water known to be low in fluoride is labeled as purified,
deionized, demineralized, distilled, or prepared by reverse osmosis. Most
grocery stores sell these types of low-fluoride water.  Ready to feed
(no-mix) infant formula typically has little fluoride and may be preferred for
use at least some of the time.

What types of infant
formula may increase the risk for enamel fluorosis?

There are
three types of formula, including powder, which comes in bulk or single serve
packets, concentrated liquid, or ready-to-feed formula. Ready-to-feed formula
is more convenient, but also more expensive. Powder formula is usually the
least expensive, but requires mixing with water, as does the liquid
concentrate.

Ready-to-feed
formula contains little fluoride and does not contribute to enamel fluorosis.
Those types of formula that require mixing with water—powdered or liquid
concentrates—can be the child’s main source of fluoride intake (depending upon
the water source) and may contribute to this condition.

Should all parents
consider mixing formula with water from sources other than tap water?

There is no
evidence that water containing low concentrations of fluoride introduces a risk
for enamel fluorosis in the developing teeth of young children. Some tap water
and most bottled water contain low concentrations of fluoride. Mixing
concentrate with fluoridated tap water on an occasional basis is unlikely to be
of much consequence.  For infants whose primary nutrition source is
formula from concentrates, parents should take into consideration the fluoride
concentration in their water source when making decisions about mixing formula.

How can I find out
what the concentration of fluoride is in my tap water?

The best
source of information on fluoride levels in your water system is your local
water utility. Other knowledgeable sources may be a local public health
authority, dentist, dental hygienist, or physician. Nearly all tap water
contains some natural fluoride, but, depending on the water system, the
concentration can range from very low (0.2 mg/L fluoride or less) to very high
(2.0 mg/L fluoride or higher). Approximately 69% of all public water systems
serving about 184 million people have optimally adjusted fluoride in their
water—that is between 0.7 and 1.2 mg/L fluoride.

Is all bottled
water low in fluoride?

Most bottled
water contains low fluoride concentrations; however, much variation exists—some
brands may contain optimal or higher levels. Because there currently is no
requirement to display the fluoride concentration on bottle labels, you may
need to contact the bottler to learn the level of fluoride in bottled drinking
water. Certain types of bottled water are, by definition, always low in
fluoride and can reliably be used for mixing formula. Water labeled as
purified, distilled, deionized, demineralized, or produced through reverse
osmosis are always low in fluoride.

Will using only
low fluoride water to mix formula eliminate the risk for fluorosis?

Using only
water with low fluoride levels to mix formula will not eliminate the risk of
enamel fluorosis. But following such a practice may reduce the chance of
fluorosis occurring. This condition occurs among some children in all
communities, even in communities with a low natural concentration of fluoride
in the water. Other factors that contribute to developing fluorosis include
swallowing of toothpaste and use of dietary supplements that include fluoride
(tablets or drops).

What can be done
to reduce my child’s chance of developing fluorosis?

CDC has developed
recommendations to reduce the risk for enamel fluorosis. Remember, fluorosis
can only occur during the time of enamel formation, before the teeth come into
the mouth. Young children who use multiple sources of fluoride such as fluoride
toothpaste, dietary supplements, and water with optimal or higher natural
fluoride have a higher risk for this condition. Community water fluoridation is
a safe, effective, and inexpensive way to prevent tooth decay, and CDC
recommends continuing and extending this practice. Steps can be taken to reduce
the potential for enamel fluorosis associated with drinking water and other
fluoride products.

Adapted
From CDC’s Community Water Fluoridation, August 2009