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Cryolite (Gowan; Elf Atochem). August 7, 1997. Pesticide Tolerance Petition. Federal Register.
http://www.epa.gov/fedrgstr/EPA-PEST/1997/August/Day-07/p20845.htm
[Federal Register: August 7, 1997 (Volume 62, Number 152)]
[Notices]
[Page 42546-42551]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07au97-76]
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ENVIRONMENTAL PROTECTION AGENCY
[PF-750; FRL-5727-3]
Pesticide Tolerance Petition; Notice of Filing
AGENCY: Environmental Protection Agency (EPA)
[[Page 42547]]
ACTION: Notice of filing.
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SUMMARY: This notice announces the filing of a pesticide petition
proposing regulations amending the established tolerances for residues
of the insecticidal fluorine compounds cryolite and/or synthetic
cryolite (sodium aluminum fluoride or sodium aluminofluoride) in or on
cabbage, citrus fruits, collards, eggplant, lettuce, peaches, and
tomatoes; and establishing tolerances for the processed foods, raisins
and tomato paste. This notice includes a summary of the petition that
was prepared by the petitioner, The Cryolite Task Force.
DATES: Comments, identified by the docket control number [PF-750]. must
be received on or before September 8, 1997.
ADDRESSES: By mail submit written comments to: Public Information and
Records Integrity Branch, Information Resources and Services Division
(7506C), Office of Pesticide Programs, Environmental Protection Agency,
401 M St., SW., Washington, DC 20460. In person bring comments to: Rm.
1132, CM #2, 1921 Jefferson Davis Highway, Arlington, VA.
Comments and data may also be submitted electronically by following
the instructions under ``SUPPLEMENTARY INFORMATION.'' No confidential
business information should be submitted through e-mail.
Information submitted as a comment concerning this document may be
claimed confidential by marking any part or all of that information as
``Confidential Business Information'' (CBI). CBI should not be
submitted through e-mail. Information marked as CBI will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2. A copy of the comment that does not contain CBI must be submitted
for inclusion in the public record. Information not marked confidential
may be disclosed publicly by EPA without prior notice. All written
comments will be available for public inspection in Rm. 1132 at the
address given above, from 8:30 a.m. to 4 p.m., Monday through Friday,
excluding legal holidays.
FOR FURTHER INFORMATION CONTACT: By mail: Jackie Mosby (7505C),
Registration Division, Office of Pesticide Programs, Environmental
Protection Agency, 401 M St., SW., Washington, DC 20460. Office
location, telephone number, and e-mail address: Rm. 203, CM #2, 1921
Jefferson Davis Highway, Arlington, VA, (703) 305-6792, e-mail: mosby-
romney.jackie@epamail.epa.gov.
SUPPLEMENTARY INFORMATION: EPA has received a pesticide petition from
The Cryolite Task Force c/o Gowan, P.O. Box 5568, Yuma, AZ 85366. The
petition proposes, pursuant to section 408 of the Federal Food, Drug,
and Cosmetic Act (FFDCA), 21 U.S.C. 346a, to amend 40 CFR 180.145 by:
(1) Increasing the established tolerances for residues of the
insecticidal fluorine compounds cryolite and /or synthetic cryolite in
or on the agricultural commodities as listed below; (2) establishing
separate tolerances for the residues in or on head and leaf lettuce;
and (3) establishing tolerances for the residues in the processed
foods, raisins at 55 ppm, and tomato paste at 45 ppm.
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Commodity Current Proposed
------------------------------------------------------------------------
cabbage 7 ppm 45 ppm
citrus fruits 7 ppm 95 ppm
collards 7 ppm 35 ppm
eggplant 7 ppm 30 ppm
lettuce 7 ppm
lettuce, head 180 ppm
lettuce, leaf 40 ppm
peaches 7 ppm 10 ppm
raisins none 55 ppm
tomatoes 7 ppm 30 ppm
tomato paste none 45 ppm
------------------------------------------------------------------------
EPA has determined that the petition contains data or information
regarding the elements set forth in section 408(d)(2); however, EPA has
not fully evaluated the sufficiency of the submitted data at this time
or whether the data supports granting of the petition. Additional data
may be needed before EPA rules on the petition.
As required by section 408(d) of the FFDCA, as recently amended by
the Food Quality Protection Act, The Cryolite Task Force included in
the petition a summary of the petition and authorization for the
summary to be published in the Federal Register in a notice of receipt
of the petition. The summary represents the views of The Cryolite Task
Force; EPA is in the process of evaluating the petition. As required by
section 408(d)(3) EPA is including the summary as a part of this notice
of filing. EPA may have made minor edits to the summary for purposes of
clarity.
The official record for this notice of filing, as well as the
public version, has been established for this notice of filing under
docket control number PF-750 (including comments and data submitted
electronically as described below). A public version of this record,
including printed, paper versions of electronic comments, which does
not include any information claimed as CBI, is available for inspection
from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal
holidays. The official record is located at the address in
``ADDRESSES'' at the beginning of this document.
Electronic comments can be sent directly to EPA at:
opp-docket@epamail.epa.gov
Electronic comments must be submitted as an ASCII file avoiding the
use of special characters and any form of encryption. Comment and data
will also be accepted on disks in Wordperfect 5.1 file format or ASCII
file format. All comments and data in electronic form must be
identified by the docket control number PF-745 and appropriate petition
number. Electronic comments on this notice may be filed online at many
Federal Depository Libraries.
List of Subjects
Environmental Protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Reporting and
recordkeeping requirements.
Dated: July 31, 1997.
Peter Caulkins,
Acting Director, Registration Division, Office of Pesticide Programs.
Summary of Petition
This informative summary is submitted by the Cryolite Task Force
(Consortium No. 62569), under section 408 of FFDCA, as most recently
amended by FQPA. The Cryolite Task Force is comprised of Elf Atochem
North America and Gowan Company. The Cryolite Task Force previously has
petitioned the Agency to amend tolerances for residues of cryolite and/
or synthetic cryolite (sodium aluminofluoride) in or on the raw
agricultural commodities: lettuce (head), lettuce (leaf), cabbage,
collards, eggplant, tomatoes, citrus (crop group) and peaches and to
establish tolerances for residues of cryolite in processed foods:
raisins and tomato paste. EPA approved these new and revised tolerances
in the Cryolite Reregistration Eligibility Decision (RED) and noted its
intent to propose these in the Federal Register. However, prior to
publication of the new regulations, FQPA specified additional
requirements for tolerance petitions. The purpose of this submission is
to provide the additional information specified in the FQPA.
[[Page 42548]]
Cryolite Task Force
PP 5F4599
A. Residue Data
1. Name, identity, and composition of the residue. Cryolite (sodium
aluminofluoride, sodium hexafluoroaluminate, or sodium aluminum
fluoride) is a fluorine containing insecticide which is found in
naturally occuring mineral deposits and also is produced synthetically.
Empirical Formula: Na3AlF6
Molecular Weight: 209.97
CAS Registry No.: 15096-52-3
OPP Chemical Code: 075101
A Reregistration Eligibility Decision (RED) was issued for cryolite
in August 1996. As documented in the RED, the Agency has determined
that plant residues are inorganic surface residues of cryolite,
measured as total fluoride; and that the residue of concern in animals
also is total fluoride.
Provisions in the FQPA which are relevant to degradates or
metabolites of pesticide chemical residues are not applicable to
elemental fluorine.
Magnitude of the residue in plants. Residue data covering all of
the uses associated with the RAC tolerances requested by this petition
have been reviewed and approved by the Agency (see the Cryolite RED,
pages 19 - 26). The proposed tolerance amendments are summarized,
below:
Lettuce (head) - 180 ppm
Lettuce (leaf) - 40 ppm
Cabbage - 45 ppm
Collards - 35 ppm
Eggplant - 30 ppm
Tomato - 30 ppm
Citrus fruit group - 95 ppm
Peaches - 10 ppm
2. Magnitude of the residue in processed food/feed. As documented
in the RED, EPA has concluded that acceptable processing studies
support the proposed tolerances of 45 ppm for tomato paste and 55 ppm
for raisins.
3. Directions for use. Use directions consistent with the proposed
revised RAC and new processed food tolerances have been approved by the
Agency. Labeling was approved by EPA for the Gowan registration (10163-
41) on May 10, 1995. Labeling was approved for the Atochem registration
(4581-116) on October 26, 1995.
4. Analytical method. EPA concluded in the cryolite RED that
adequate methodology is available for data collection and tolerance
enforcement. Methods for both plant residues and animal tissues have
undergone successful Agency validation and will be published in the
Pesticide Analytical Manual, Vol. II. Using these methods, total
fluoride is determined using a pH/ion meter with a fluoride-specific
electrode. The limit of quantitation is 0.05 ppm. The residue
analytical method does not distinguish between naturally occuring
fluoride and fluoride resulting from agricultural use of cryolite.
Current FDA multi-residue screening protocols are not appropriate for
inorganic fluoride residues.
5. Practical methods for removing residues. Plant residues are
inorganic surface residues of cryolite. Data reviewed by EPA for the
RED show that washing, peeling, and trimming are effective methods of
removing these residues.
6. Plant metabolism. EPA concluded in the cryolite RED that the
qualitative nature of the residue in plants is understood and that
plant residues are inorganic surface residues of cryolite which are
measured as fluoride.
7. Animal metabolism. EPA concluded in the cryolite RED that
cryolite metabolism in animals manifests itself as free fluoride, that
the qualitative nature of the residue is understood and that total
fluoride is the residue of concern.
8. Magnitude of the residue in meat, milk, poultry and eggs. EPA
concluded in the cryolite RED that there is no reasonable expectation
of finite fluoride residues in ruminant or poultry tissues as a result
of livestock ingestion of cryolite.
B. Toxicological Data
The cryolite RED concluded that the toxicological data base
supports a reregistration eligibility decision for numerous crops,
including head lettuce, leaf lettuce, cabbage, collards, eggplant,
tomatoes, citrus (crop group), grapes, and peaches. No additional
toxicology requirements were specified in the RED. The cryolite residue
of toxicological concern is fluoride; and health effects identified for
fluoride in humans and animals are skeletal and dental fluorosis.
Dental fluorosis (mottling of tooth enamel) is not considered to be an
adverse effect. Further, the Agency has determined that although
fluoride accumulation is demonstrated in a number of studies, the
accumulation itself is not considered an adverse effect.
1. Acute toxicity. A rat acute oral toxicity study (MRID 00138096)
showed an LD50 greater than 5,000 milligrams/kilograms (mg/
kg). A rabbit acute dermal toxicity study (MRID 00128107) demonstrated
an LD50 of 2,100 mg/kg. An LC50 > 2.06 mg/L and <
5.03 mg/L was seen in an acute inhalation study with rats (MRID
00128107). Technical cryolite is a moderate eye irritant in rabbits
(MRID 00128106). Cryolite is not a skin irritant to rabbits (MRID
00128106) and is not a dermal sensitizer to guinea pigs (MRID
00138097).
2. Subchronic toxicity. Cryolite was tested in a 28-day range-
finding feeding study in rats (MRID 00128109) at dose levels of 0, 250,
500, 1,000, 2,000, 4,000, 10,000, 25,000 and 50,000 ppm in the diet
(representing approximately 0, 25, 50, 100, 200, 400, 1,000, 2,500 and
5,000 mg/kg/day). The only compound related effect seen in this study
was a change in coloration and physical property of the teeth. A no
observed effect level (NOEL) was not determined in this study. The
lowest observed effect level (LOEL) is 250 ppm (25 mg/kg/day) based on
dental fluorosis.
In a 90-day rat feeding study (MRID 00158000), cryolite was tested
at dose levels of 0, 50, 5,000 and 50,000 ppm (corresponding to 0, 3.8,
399.2, and 4,172.3 mg/kg/day in males and 0, 4.5, 455.9 and 4,758.1 mg/
kg/day in females). The NOEL was 50 ppm (3.8 mg/kg/day) for effects
other than fluoride accumulation. The LOEL was 5,000 ppm (399.2 mg/kg/
day) based on lesions observed in the stomach. Fluoride accumulated at
all dose levels in this study.
Cryolite was tested in a 90-day dog feeding study (MRID 00157999)
at dose levels of 0, 500, 10,000, and 50,000 ppm (corresponding to 0,
17, 368, and 1,692 mg/kg/day). The NOEL was 10,000 ppm (368 mg/kg/day).
The LOEL was 50,000 ppm (1,692 mg/kg/day) for effects other than
fluoride accumulation. Fluoride accumulation occurred at all dose
levels.
A 21-day subchronic dermal toxicity study in rabbits (MRID
41224801) is considered invalid because it is likely that cryolite was
ingested by the test animals during the study. For this reason, the
systemic dermal NOEL and LOEL could not be determined from this study.
EPA noted in the RED that an additional subchronic dermal study is not
necessary, because based on its chemical/physical properties, cryolite
would not be absorbed through the skin to any appreciable extent.
3. Genotoxicity. Cryolite was negative in an Ames reverse mutation
test (MRID 41838401) using Salmonella typhimurium with and without
activation at dose levels of 167, 500, 1,670, 5,000, 7,500 and 10,000
g/plate. Cryolite was tested in an in vitro chromosome
aberration assay (MRID 41838402) using human lymphocytes at 100, 500,
and 1,000 g/ml, with and without activation. The results were
negative. Cryolite also was negative in an unscheduled DNA synthesis
study (MRID 41838403) with rat hepatocytes
[[Page 42549]]
at dose levels up to and including 50 g/ml.
4. Chronic toxicity. The Agency concluded in the cryolite RED that
the available information does not support the regulation of cryolite
insecticides as carcinogens. EPA has classified cryolite as a Group
``D'' chemical (not classifiable as to human carcinogenicity.''
Further, EPA has noted that fluoride has been the subject of a
comprehensive review by the National Research Council (National Academy
of Sciences Subcommittee of Health Effects of Ingested Fluoride) who
concluded that ``. . . the available laboratory data are insufficient
to demonstrate a carcinogenic effect of fluoride in animals'' and that
``. . .the weight of evidence from more that 50 epidemiological studies
does not support the hypothesis of an association between fluoride
exposure and increased cancer risk in humans.'' As stated in the
Federal Register of May 8, 1996, and reiterated in the cryolite RED,
the Agency is in agreement with the conclusions reached by the National
Academy of Science (NAS).
The following specific chronic/oncogenicity studies are included in
the cryolite toxicology data base:
A 2-year bioassay in B6C3F1 mice (HED DOC No. 009682) was conducted
by the National Toxicology Program (NTP) using sodium fluoride as the
test material at dose levels of 0, 25, 100, and 175 ppm, in water,
representing 0, 2.4, 9.6, and 16.7 mg/kg/day in males and 0, 2.8, 11.3,
and 18.8 mg/kg/day in females. The NOEL was less than 25 ppm (2.4 mg/
kg/day). The LOEL was 25 ppm (2.4 mg/kg/day) based on attrition of the
teeth in males, discoloration and mottling of the teeth in males and
females and increased bone fluoride in both sexes. NTP considered that
there was ``no evidence'' of carcinogenic activity in male and female
mice. A 2-year bioassay in F344/N rats (HED DOC No. 009682) also was
conducted by the National Toxicology Program (NTP) using sodium
fluoride as the test material at dose levels of 0, 25, 100, and 175
ppm, in water, representing 0, 1.3, 5.2 and 8.6 mg/kg/day in males and
0, 1.3, 5.5 and 9.5 mg/kg/day in females. Osteosarcoma of the bone was
observed only in one male of fifty (1/50) in the 100 ppm group and in
three of eighty (3/80) males in the 175 ppm group. The NOEL was less
than 25 ppm (1.3 mg/kg/day). The LOEL was 25 ppm (1.3 mg/kg/day) based
on mottling of teeth, dentine incisor dysplasia, increased serum, urine
and bone fluoride levels in males and females and incisor odontoblast
and incisor ameloblast degeneration in males. NTP considered that there
was ``equivocal evidence'' of carcinogenic activity in male rats in
this study and ``no evidence'' of carcinogenic activity in female rats.
EPA concluded in the cryolite RED that the NTP studies utilizing
sodium fluoride in lieu of cryolite satisfy the guideline study
requirements for both the rodent chronic feeding study and the rat
carcinogenicity study. Fluoride has been identified as the residue of
toxicological concern in cryolite and synthetic cryolite and these
compounds act as free fluoride. It may be noted that the NTP studies,
which utilized freely soluble NaF represent a ``worst-case''
toxicological scenario on a ppm basis compared to what would be
expected with cryolite per se, from which fluoride ion dissociation is
much more limited.
A 1-year chronic dog feeding study (MRID 42575101) was conducted
with cryolite at dose levels of 0, 3,000, 10,000, and 30,000 ppm,
representing 0, 95, 366, and 1,137 mg/kg/day in males and 0, 105, 387,
and 1,139 mg/kg/day in females (in terms of fluoride the doses are 0,
51, 198, and 614 mg F/kg/day for males and 0, 57, 209, and 615 mg F/kg/
day for females). The NOEL was less than 3,000 ppm (95 mg/kg/day in
males and 105 mg/kg/day in females). The LOEL was 3,000 ppm based on
increases in emesis, nucleated cells in males, renal lesions and a
decrease in urine specific gravity in females.
5. Reproductive toxicity. A two-generation rat reproduction study
(MRID 43387501) was conducted with cryolite at dietary dose levels of
0, 200, 600, and 1,800 ppm (representing 0, 14, 42, and 128 mg/kg/day
for males and 0, 16, 49, and 149 mg/kg/day for females, respectively,
during premating). The systemic toxicity NOEL was not determined. The
LOEL for systemic toxicity was 200 ppm (15 mg/kg/day) based on dental
fluorosis. The NOEL and LOEL for reproductive toxicity were 600 and
1,800 ppm, respectively (46 and 138 mg/kg/day) based on decreased pup
body weights.
The National Research Council (NRC) has reviewed the potential for
reproductive effects from fluoride per se. In the report Health Effects
of Ingested Fluoride, the NRC concluded that:
There have been reports of adverse effects on reproductive
outcomes associated with high levels of fluoride in many animal
species. In most of the studies, however, the fluoride
concentrations associated with adverse effects were far higher than
those encountered in drinking water. The apparent threshhold
concentration for inducing reproductive effects was 100 mg/L in
mice, rats, foxes and cattle; 100-200 mg/L in minks, owls and
kestrels; and over 500 mg/L in hens. Based on these findings, the
subcommittee concludes that the fluoride concentrations associated
with adverse reproductive effects in animals are far higher than
those to which human populations are exposed. Consequently,
ingestion of fluoride at current concentrations should have no
adverse effects on human reproduction.
6. Developmental toxicity. A developmental toxicity study was
performed with cryolite in rats (MRID 00128112) at dose levels of 0,
750, 1,500 and 3,000 mg/kg/day (gavage). The NOEL for both
developmental and maternal toxicity was 3,000 mg/kg/day. At this dose
level, the only observation was whitening of the teeth of dams.
A developmental toxicity study was conducted in female mice (MRID
42297902) with cryolite at dose levels of 0, 30, 100, and 300 mg/kg/day
(gavage). The NOEL for maternal toxicity was 30 mg/kg/day and the LOEL
was 100 mg/kg/day based on a single mortality in this group. Fetuses at
300 mg/kg/day exhibited bent ribs and bent limb bones. The NOEL for
developmental toxicity was 100 mg/kg/day. The LOEL was 300 mg/kg/day
based on an increase in bent ribs and bent limbs.
A range-finding developmental toxicity study in female rabbits
(MRID 42297901) tested cryolite at dose levels of 0, 10, 30, 100, 300,
and 1,000 mg/kg/day (gavage). The NOEL for maternal toxicity was
determined to be 10 mg/kg/day and the LOEL was 30 mg/kg/day based on an
increased incidence of soft stool and dark colored feces and decreased
defecation and urination. The NOEL for developmental toxicity was 30
mg/kg/day. The developmental LOEL could not be assessed due to
excessive maternal toxicity at dose levels of 30 mg/kg/day.
7. Metabolism/metabolite toxicity. As noted in the RED, cryolite
behaves toxicologically as free fluoride. That is, dissociation
produces free fluoride ions which are assimilated into bone. There are
numerous references in the open literature concerning the metabolism of
cryolite and other fluoride salts. The National Research Council
concluded in their 1993 comprehensive report entitled Health Effects of
Ingested Fluoride that fluoride is readily absorbed by the gut and
rapidly becomes associated with teeth and bones. The remaining fluoride
is eliminated almost exclusively by the kidneys with the rate of renal
clearance related directly to urinary pH.
8. Endocrine effects. The two-generation rat reproduction study,
the developmental toxicity studies in rats, rabbits and mice and the
dog chronic study summarized above did not
[[Page 42550]]
demonstrate any effects with cryolite that are similar to those
produced by naturally occuring estrogens, or other endocrine effects.
No endocrine effects were determined in the rat and mouse NTP studies.
In addition, it should be noted that National and International
regulatory organizations (U.S. EPA Office of Water, U.S. DHHS, the
Canadian Government and the World Health Organization) have assessed
potential health risks from exposure to fluoride. EPA has concluded
that the endpoints and estimated effect levels documented by these
organizations are similar and that the health effects of fluoride in
animals and humans include dental and skeletal fluorosis. Endocrine
effects have not been recognized as toxicological endpoints for
fluoride by any worldwide regulatory authority.
C. Aggregate Exposure
1. Dietary exposure-food. As noted in the RED, the Agency has
estimated dietary exposure to cryolite using reassessed tolerances for
all crops (including the proposed tolerances discussed in this
petition) and percent of crop treated assumptions. In the RED EPA
estimated dietary exposure to cryolite from all crops to be
approximately 0.020 mg/kg/day for the U.S. population, 0.024 mg/kg/day
for children ages 1 to 6, 0.015 mg/kg/day for children ages 7 to 12 and
0.028 mg/kg/day for the highest exposed subgroup (nursing females 13+
years). The Task Force believes that these exposure estimates in fact
greatly overstate actual dietary exposure since cryolite tolerance
levels, rather than residues actually present at the consumer level
were used by EPA in the exposure assessments.
2. Dietary exposure-drinking water. In the Environmental Fate
Assessment conducted for the RED, the Agency concluded that the use of
cryolite should have negligible impacts on fluoride levels in ground
and surface water. For this reason, the contribution of cryolite to
potential exposure to fluoride from drinking water need not be
considered in the aggregate risk assessment.
However, fluoride is intentionally supplemented to drinking water
for prevention of dental caries and may also be present at natural
background levels. The U.S. Public Health Service recommends an optimal
fluoride concentration of 0.7 - 1.2 mg/L to prevent dental caries and
minimize dental fluorosis.
Fluoride levels in public drinking water are regulated under the
Safe Drinking Water Act. A Maximum Concentration Limit (MCL) of 4.0 mg/
L (0.114 mg/kg/day) has been established. EPA has estimated previously
that levels of fluoride in/on food from the agricultural use of
cryolite plus fluoride levels in U.S. drinking water supplies results
in a daily dietary intake of fluoride of approximately 0.095 mg/kg/day.
This is substantially less than the Maximum Concentration Limit (MCL)
of 4.0 mg/L (0.144 mg/kg/day), a level which provides no known or
anticipated adverse health effect as determined by the Surgeon General.
As noted in the RED, the Agency has concurred with the findings of the
Surgeon General that adverse health effects have not been found in the
U. S. population below 8 mg F/L (0.23 mg/kg/day).
3. Non-dietary exposure. Cryolite is used almost exclusively as an
agricultural crop protection insecticide. Conceivably, cryolite also
could be used in outdoor homeowner/residential sites for insect control
in ornamentals and shade trees. Cryolite is not registered for either
lawn or crack and crevice treatments. EPA concluded in the RED that a
post-application exposure assessment for cryolite (including both
occupational and residential exposure) was not appropriate since no
toxicological endpoints relevant to non-dietary exposure have been
identified for cryolite.
The Task Force concludes that non-dietary exposure represents a
negligible component of potential aggregate exposure to cryolite and
need not be considered in the aggregate risk assessment.
D. Cumulative Effects
The residue of toxicological concern in cryolite is fluoride.
Although fluoride supplements in drinking water are not considered to
be pesticidal substances, the dietary contribution of drinking water to
overall fluoride exposure has been discussed elsewhere in this summary.
Current tolerances for insecticidal fluorine-containing compounds are
limited to cryolite and synthetic cryolite. For this reason,
consideration of potential cumulative effects of residues from
pesticidal substances other than sodium aluminofluoride with a common
mechanism of toxicity are not applicable.
E. Safety Determination
1. U.S. population. As discussed above, non-dietary exposure to
cryolite is negligible. As stated in the RED, the OPP's Health Effects
Division's RfD Peer Review Committee concluded that ``For acute dietary
exposure, no endpoint of concern could be found from which an acute
dietary risk assessment. . .should be conducted.'' There was no
endpoint for acute dietary exposure since acute toxicity in animal
studies is absent until very high doses of cryolite were used. For
chronic dietary exposure to cryolite, EPA has concluded that rather
than establishing a traditional Reference Dose (RfD), a weight-of-the-
evidence risk assessment is a more appropriate approach. The endpoint
for chronic dietary exposure is skeletal fluorosis. As part of the RED
decision for cryolite, EPA conducted a chronic exposure analysis using
the Dietary Risk Evaluation System (DRES). This analysis was performed
using the proposed tolerances that are the subject of this petition.
The Agency has approximated that total dietary fluoride levels in food
plus drinking water is 0.095 mg/kg/day. Of this total exposure, the
dietary (food) contribution is about 0.020 mg/kg/day for the U.S.
population and 0.028 mg/kg/day for the highest exposed subgroup. These
exposure estimates likely overstate actual dietary exposure, since
marketbasket residue levels for cryolite have not been considered. As
noted above, the Agency has concurred with the findings of the Surgeon
General that adverse health effects (skeletal fluorosis) have not been
found in the U. S. population below 8 mg F/L (0.23 mg/kg/day).
2. Infants and children. EPA has concluded previously that in rats,
the developmental NOEL for cryolite is 3,000 mg/kg/day (1,584 mg/kg/day
F), that in mice, the developmental NOEL is 100 mg/kg/day (52.8 mg/kg/
day F) and that in rabbits, the developmental NOEL is 30 mg/kg/day
(15.8 mg/kg/day F). The NOEL for reproductive toxicity of cryolite
determined in a 2-generation rat reproduction study was determined by
the Agency to be 46 mg/kg/day (24.3 mg/kg/day F). These data show
clearly that no additional margin of safety is required for exposure of
infants and children to cryolite. The developmental NOEL ranges from
more than 166x (rabbit) to more than 16,000x (rat) for the maximum
combined exposure of infants and children to residues of fluoride from
all agricultural uses of cryolite plus drinking water. The reproductive
NOEL is about 256x greater than maximum combined exposure of infants
and children to residues of fluoride.
F. International Tolerances
No Codex, EC or other international tolerances are in effect for
cryolite; thus potential dietary exposure to fluoride from the
agricultural use of cryolite on
[[Page 42551]]
crops would not include imported foodstuffs.
[FR Doc. 97-20845 Filed 8-6-97; 8:45 am]
BILLING CODE 6560-50-F