United States
Environmental Protection OfficeofWater EPA-822-F-11-001
L Agency AMAT .lamia™ 9011
New Fluoride Risk Assessment and Relative Source
Contribution Documents
Summary
Fluoride is an inorganic ion found in drinking
water because of its presence in the earth's crust,
anthropogenic releases to the environment,
and/or due to its addition to treated water to
prevent cavities. The decision on whether to add
fluoride to drinking water is made by state or
local governments with technical support from
the Department of Health and Human Services
and is not governed by the Safe Drinking Water
Act.
Background
EPA established regulations for fluoride ion in
drinking water in 1986. A non-enforceable
Maximum Contaminant Level Goal (MCLG) of
4 mg/L was established to protect against
crippling skeletal fluorosis. The enforceable
Maximum Contaminant Level (MCL) was
established at the same time, requiring systems
to install treatment to remove some fluoride in
situations where the total fluoride concentration
of the delivered water exceeds 4 mg/L.
EPA also established a non-enforceable
Secondary Maximum Contaminant Level
(SMCL) of 2 mg/L to protect against moderate
dental fluorosis (discoloration of the tooth
enamel), a cosmetic effect. Although water
systems are not required to comply with
SMCLs, when the SMCL for fluoride is
exceeded, systems must inform customers of the
risk for dental fluorosis in children. The
notification includes recommending that
consumers use an alternative drinking water
source for those under nine years of age and
consult with a dental professional on measures
that can reduce total fluoride exposure.
The scientific basis for the health assessments
that underlie the MCLG and SMCL was
evaluated by the National Research Council
(NRC) at the request of EPA in 1993. In 2003,
EPA asked for another NRC review due to the
number of new studies on the health effects of
ingested fluoride in humans and laboratory
animals.
The most recent NRC panel recommended in
2006 that EPA conduct a new quantitative risk
assessment for severe dental fluorosis, the risk
for increased bone fractures as related to
fluoride, and the less than crippling form of
skeletal fluorosis (Stage II skeletal fluorosis).
Some dose-response data are available for
severe dental fluorosis, cavities that may be
associated with this defect, and the relation
between fluoride and skeletal fractures. The
collection of dose-response data on skeletal
fluorosis remains a research need.
The findings of the 2006 NRC panel diverged
from those of the 1993 panel in categorizing
severe dental fluorosis resulting in pitting of the
tooth enamel as the health endpoint that should
be evaluated. The 2006 panel also concluded
that the present MCL of 4 mg/L was not
protective for severe dental fluorosis and might
not be protective for the skeletal fracture
endpoint. The NRC report does not question the
beneficial effects for fluoride at levels practiced
for fluoridation programs.
Current Status and Next Steps
EPA has completed and peer-reviewed a
quantitative dose-response assessment based on
the available data for severe dental fluorosis as
recommended by NRC. Additional research will
be necessary to obtain dose-response data
amenable to a quantitative risk assessment for
Stage II skeletal fluorosis and/or skeletal
fractures. The dose-response assessment
provides a reference dose based on the critical
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health effect of pitting of the enamel in severe
dental fluorosis.
EPA has also completed and peer-reviewed a
document on environmental exposure of
children and adults to fluoride and the relative
source contribution (RSC) for water. The RSC
is needed in order to derive the MCLG from the
dose-response assessment.
Both documents are posted on EPA's website at:
http://water, epa. gov/action/advisories/drinking/
fluoride jndex. cfm.
The Agency will review the new risk assessment
of fluoride along with other information (e.g.,
availability of analytical methods, feasibility of
treatment, data on occurrence and exposure) to
determine whether it is appropriate to revise the
drinking water goal and/or standard.
For More Information
Contact Joyce Donohue at 202-566-1098 or by
email at donohue .i ovce@epa. gov.
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