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Fluorine (soluble fluoride)
CASRN 7782-41-4
Contents
0053
Fluorine (soluble fluoride); CASRN 7782-41-4
Health assessment information on a chemical substance is included in IRIS only
after a comprehensive review of chronic toxicity data by U.S. EPA health
scientists from several Program Offices and the Office of Research and
Development. The summaries presented in Sections I and II represent a
consensus reached in the review process. Background information and
explanations of the methods used to derive the values given in IRIS are
provided in the Background Documents.
STATUS OF DATA FOR Fluorine (soluble fluoride)
File On-Line 01/31/1987
Category (section) Status Last Revised
----------------------------------------- -------- ------------
Oral RfD Assessment (I.A.) on-line 06/01/1989
Inhalation RfC Assessment (I.B.) no data
Carcinogenicity Assessment (II.) no data
_I. CHRONIC HEALTH HAZARD ASSESSMENTS FOR NONCARCINOGENIC EFFECTS
__I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
Substance Name -- Fluorine (soluble fluoride)
CASRN -- 7782-41-4
Primary Synonym -- Flouride
Last Revised -- 06/01/1989
The oral Reference Dose (RfD) is based on the assumption that thresholds exist
for certain toxic effects such as cellular necrosis. It is expressed in units
of mg/kg-day. In general, the RfD is an estimate (with uncertainty spanning
perhaps an order of magnitude) of a daily exposure to the human population
(including sensitive subgroups) that is likely to be without an appreciable
risk of deleterious effects during a lifetime. Please refer to the Background
Document for an elaboration of these concepts. RfDs can also be derived for
the noncarcinogenic health effects of substances that are also carcinogens.
Therefore, it is essential to refer to other sources of information concerning
the carcinogenicity of this substance. If the U.S. EPA has evaluated this
substance for potential human carcinogenicity, a summary of that evaluation
will be contained in Section II of this file.
___I.A.1. ORAL RfD SUMMARY
Critical Effect Experimental Doses* UF MF RfD
-------------------- ----------------------- ----- --- ---------
Objectionable dental NOAEL: 1 ppm (converted 1 1 6E-2
fluorosis, a cosmetic 0.06 mg/kg/day mg/kg/day
effect
LOAEL: 2 ppm
Epidemiologic Study
in Children
Hodge, 1950, cited
in Underwood, 1977
*Conversion Factors: see text
___I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
Hodge, H.C. 1950. The concentration of fluorides in drinking water to give
the point of minimum caries with maximum safety. J. Am. Dent. Assoc. 40:
436. Cited in: Underwood, E.J. 1977. Trace Elements in Human and Animal
Nutrition. Academic Press, NY.
Fluoride-related compounds are used in the prevention of dental caries.
Extensive human epidemiologic studies with large populations have been carried
out over the last 40 years. The NOAEL (1 ppm) and LOAEL (2 ppm) in drinking
water are defined within a narrow dose range.
Hodge (1950) studied children consuming fluoride in their drinking water.
Fluoride levels of 0-14 ppm were investigated. Dental mottling was the
parameter of interest. Fluoride levels of 2-10 ppm produced a linear dose-
response curve (increasing mottling with increasing dose). Fluoride levels of
0.1-1.0 ppm produced no observable effect. An assumption of 20 kg bw and 1
L/day water consumption for children was used, since the children studied were
12-14 years old. It is further assumed that a 20-kg child consumes 0.01 mg of
fluoride/kg bw/day in the diet (50 FR 20164). Thus, a total intake would be
approximately 0.06 mg/kg/day.
___I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
UF -- Uncertainty factors were not deemed necessary since the NOAEL is that of
the critical effect (i.e., dental fluorosis) in a sensitive population of
humans (i.e., children) for a length of exposure that encompasses both the
critical effect and the sensitive population.
MF -- None
___I.A.4. ADDITIONAL COMMENTS (ORAL RfD)
Dental fluorosis results from excess exposure to fluoride during the age of
calcification of the teeth (up to about 8 years of age for anterior teeth).
Dental fluorosis in its mild form is characterized by white opaque areas
covering 50% of a given tooth; in its severe form, dental fluorosis is
characterized by brown to black stains and pitting (50 FR 20164). There is
considerable controversy over whether objectionable dental fluorosis (moderate
and severe) is a toxic and/or adverse health effect. However, the U.S. EPA
has determined that objectionable dental fluorosis is a cosmetic effect and
not a toxic and/or adverse health effect (50 FR 47142). Numerous
epidemiologic studies have been conducted in the U.S. concerning the
relationship between dental fluorosis and fluoride levels in drinking water
(50 FR 20164). Based on these studies, the NOAEL for objectionable dental
fluorosis is approximately 1.0 ppm fluoride in drinking water. Assuming that
a child weighs 20 kg, drinks 1.0 L of water/day and ingests fluoride at 0.01
mg/kg/day in the diet (50 FR 20164), a NOAEL of 1 ppm fluoride in drinking
water corresponds to 0.06 mg/kg/day. Since data are available for the only
susceptible population (children), an uncertainty factor of 1 is appropriate.
It has been estimated that the development of crippling skeletal fluorosis in
man requires the consumption of 20 mg or more of fluoride/person/day over a
20-year period, i.e., 0.28 mg/kg/day (U.S. EPA, 1985). While the NOEL for
crippling skeletal fluorosis in humans is unknown, a safe level of fluoride
exposure can be determined. No cases of crippling skeletal fluorosis have
been observed in the United States associated with the consumption of 2 L of
water/day containing 4 ppm fluoride (50 FR 20614). Assuming a 70 kg adult
ingests 0.01 mg fluoride/day in the diet and consumes 8 mg fluoride/ day in
drinking water (2 L/day containing 4 ppm fluoride), this would correspond to a
total intake of 0.12 mg/kg/day. Thus, 0.12 mg fluoride/kg/day is a safe
exposure level for this more severe endpoint in adults.
___I.A.5. CONFIDENCE IN THE ORAL RfD
Study -- High
Data Base -- High
RfD -- High
Confidence in both the study and the data base is high because the large
number of studies conducted in children all support the chosen NOAEL.
Confidence in the RfD is high because little uncertainty remains in the
toxicity data base.
___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
Source Document -- U.S. EPA. 1985. Federal Register, Vol. 50, p. 20164,
47142.
ECAO-Cincinnati Internal Review, July 1985.
Other EPA Documentation -- None
Agency Work Group Review -- 08/05/1985, 02/05/1986, 02/26/1986
Verification Date -- 02/26/1985
___I.A.7. EPA CONTACTS (ORAL RfD)
Please contact the Risk Information Hotline for all questions concerning this
assessment or IRIS, in general, at (513)569-7254 (phone), (513)569-7159 (FAX)
or RIH.IRIS@EPAMAIL.EPA.GOV (internet address).
__I.B. REFERENCE CONCENTRATION FOR CHRONIC INHALATION EXPOSURE (RfC)
Substance Name -- Fluorine (soluble fluoride)
CASRN -- 7782-41-4
Primary Synonym -- Flouride
Not available at this time.
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE
Substance Name -- Fluorine (soluble fluoride)
CASRN -- 7782-41-4
Primary Synonym -- Flouride
This substance/agent has not undergone a complete evaluation and determination
under US EPA's IRIS program for evidence of human carcinogenic potential.
_VI. BIBLIOGRAPHY
Substance Name -- Fluorine (soluble fluoride)
CASRN -- 7782-41-4
Primary Synonym -- Flouride
Last Revised -- 08/01/1989
__VI.A. ORAL RfD REFERENCES
Hodge, H.C. 1950. The concentration of fluorides in drinking water to give
the point of minimum caries with maximum safety. J. Am. Dent. Assoc.
40: 436.
Underwood, E.J. 1977. Trace elements in human and animal nutrition.
Academic Press, New York. p. 347-369.
U.S. EPA. 1985. Federal Register. Vol. 50, p. 20164, 47142.
__VI.B. INHALATION RfC REFERENCES
None
__VI.C. CARCINOGENICITY ASSESSMENT REFERENCES
None
_VII. REVISION HISTORY
Substance Name -- Fluorine (soluble fluoride)
CASRN -- 7782-41-4
Primary Synonym -- Flouride
-------- -------- --------------------------------------------------------
Date Section Description
-------- -------- --------------------------------------------------------
03/31/1987 I.A.6. Documentation corrected
06/30/1988 I.A.7. Contacts switched
04/01/1989 V. Supplementary data on-line
06/01/1989 I.A.6. Work group review dates corrected
08/01/1989 VI. Bibliography on-line
01/01/1992 I.A.7. Secondary contact changed
01/01/1992 IV. Regulatory actions updated
VIII. SYNONYMS
Substance Name -- Fluorine (soluble fluoride)
CASRN -- 7782-41-4
Primary Synonym -- Flouride
Last Revised -- 01/31/1987
7782-41-4
Flouride
Fluoride
Fluoride ion
Fluoride ion(1-)
Fluorine
Fluorine, ion
Hydrofluoric acid, ion(1-)
Perfluoride
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0053.HTM
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