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cryolite (Kryocide) Pesticide Tolerance Petition Filing 4/97

ENVIRONMENTAL PROTECTION AGENCY
[PF-712; FRL-5587-7]

The Cryolite Task Force; Pesticide Tolerance Petition Filing 

AGENCY: Environmental Protection Agency (EPA). 

ACTION: Notice of filing.
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SUMMARY: This notice announces the filing of a pesticide petition proposing 
regulations establishing tolerances for residues of the insecticidal fluorine 
compounds cryolite and/or synthetic cryolite (sodium aluminum fluoride or 
sodium aluminofluoride) in or on potatoes and in processed potato waste. 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-712] must be 
received on or before April 11, 1997. 

ADDRESSES: By mail, submit written comments to: Public Response and Program 
Resources Branch, Field Operations 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 22202. 

Comments and data may also be submitted electronically by sending electronic 
mail (e-mail) to: opp-docket@epamail.epa.gov. Electronic comments must be 
submitted either in ASCII format (avoiding the use of special characters and 
any form of encryption) or in WordPerfect in 5.1 file format. All comments and 
data in electronic form must be identified by the docket control number [PF-
712]. Electronic comments on this notice may be filed online at many Federal 
Depository Libraries. The official record for this rulemaking, as well as the 
public version described above, will be kept in paper form. Additional 
information on electronic submissions can be found in Unit II. of this 
document.

Information submitted as a comment concerning this notice may be claimed 
confidential by marking any part or all of that information as "Confidential 
Business Information" (CBI). Information so marked will not be disclosed 
except in accordance with procedures set forth in 40 CFR part 2. No CBI should 
be submitted through e-mail. 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.

FOR FURTHER INFORMATION CONTACT: William Jacobs, Acting, Product Manager 14, 
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. 219, CM #2, 1921 Jefferson Davis Highway, 
Arlington, VA 22202. (703) 305-6600; e- mail: jacobs.william@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 to renew the regulations that 
established tolerances for the insecticidal fluorine compounds cryolite and/or 
synthetic cryolite in or on potatoes at 2.0 parts per million (ppm) and 
processed potato waste at 22 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 (FQPA) (Pub. L. 104-170), 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. 

I. The Cryolite Task Force's Petition Summary 

This petition is submitted by the Cryolite Task Force (Consortium No. 62569), 
under section 408 of the FFDCA, as most recently amended by the FQPA.

This submission amends petitions PP 9F3739 and FAP 1H5604 by providing the 
additional information specified by the FQPA. A permanent tolerance is 
proposed for residues of the insecticide sodium aluminofluoride (cryolite 
and/or synthetic cryolite) in or on the raw agricultural commodities (RAC) 
potatoes, as provided by the new FFDCA section 408. In addition, the 
petitioner proposes that EPA establish a permanent tolerance for residues of 
cryolite in processed potato waste, as provided under the new FFDCA section 
408. 

Time-limited tolerances for residues of sodium aluminofluoride (cryolite 
and/or synthetic cryolite) in/on potatoes and processed potato waste were 
initially granted on May 5, 1993. These tolerances expired on May 6, 1996. A 
time limitation was required initially for these regulations because a chronic 
dog feeding study and a two- generation rat reproduction study were 
outstanding. These two studies were submitted and were found acceptable in 
reviews dated April 13, 1994 (chronic dog) and February 24, 1995 (rat 
reproduction). In the Federal Register of May 8, 1996 (61 FR 20781) (FRL-5362-
6), EPA proposed establishing permanent tolerances of 2 ppm and 22 ppm for 
residues of cryolite in/on potatoes and processed potato waste, respectively. 
A 30-day comment period was specified by the Agency for these proposed 
regulations. However, prior to publication of final regulations, the FQPA 
specified additional requirements for tolerance petitions. This submission 
amends PP 9F3739 and FAP 1H5604 by providing the additional information 
specified.

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 occurring 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 May 8, 1996 Federal Register and reiterated 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.

2. Magnitude of the residue in plants. As documented in the May 8, 1996 
Federal Register and reiterated in the RED, the Agency has concluded that 
complete and acceptable crop residue data are available to support the 
proposed tolerance of 2 ppm in or on potatoes. 

Data previously reviewed by EPA show background levels of fluoride in 
untreated potatoes ranging from 0.14 ppm to 0.31 ppm. Levels of fluoride found 
in treated potatoes ranged from 0.18 ppm to 0.94 ppm. 

3. Magnitude of the residue in processed food/feed. As documented in the May 
8, 1996 Federal Register and reiterated in the RED, EPA has concluded that an 
acceptable potato processing study supports the proposed tolerance of 22 ppm 
in or on processed potato waste. This study indicates that cryolite residues 
concentrated 11x in potato peels/potato waste processed from potatoes treated 
at a 6.7x exaggerated rate. Residues did not concentrate in potato chips, 
flakes, or granules.

4. Directions for use. Labeling has been approved for foliar application to 
potatoes at up to 11.5 lbs. active ingredient (a.i.) per acre, with a maximum 
seasonal application of 92 lbs. a.i. per acre. 

5. Analytical method. EPA concluded in the May 8, 1996 Federal Register and 
reiterated 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 PAM, 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 occurring fluoride and fluoride resulting from agricultural 
use of cryolite. Current FDA multi-residue screening protocols are not 
appropriate for inorganic fluoride residues.

6. Practical methods for removing residues. Plant residues are inorganic 
surface residues of cryolite. Data previously submitted in FAP 1H5604 show 
that washing and peeling are effective methods of removing these residues.

7. Plant metabolism. EPA concluded in the May 8, 1996 Federal Register and 
reiterated 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. 

8. Animal metabolism. EPA concluded in the May 8, 1996 Federal Register and 
reiterated 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.

9. Magnitude of the residue in meat, milk, poultry and eggs. EPA concluded in 
the May 8, 1996 Federal Register and reiterated 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 was adequate for a 
reregistration eligibility decision for numerous crop uses, including 
potatoes. 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 micrograms/plate. Cryolite 
was tested in an in vitro chromosome aberration assay (MRID 41838402) using 
human lymphocytes at 100, 500, and 1,000 micrograms/ml, with and without 
activation. The results were negative. Cryolite also was negative in an 
unscheduled DNA synthesis study (MRID 41838403) with rat hepatocytes at dose 
levels up to and including 50 micrograms/ml.

4. Chronic toxicity. The Agency concluded in the May 8, 1996 Federal Register 
and reiterated in the cryolite RED that the available information does not 
support the regulation of cryolite insecticides as carcinogens. The Agency 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 May 8, 1996 Federal Register 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 NTP using sodium fluoride as the test material at dose levels of 0, 25, 
47, 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 1 male of 50 (1/ 50) in the 100 ppm group and in 3 of 80 
(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 May 8, 1996 Federal Register and reiterated 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 should 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 threshold 
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 May 8, 1996 Federal 
Register and reiterated 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 rat, 
rabbit and mouse developmental studies and the dog chronic studies summarized 
above did not demonstrate any effects with cryolite that are similar to those 
produced by naturally occurring 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 May 8, 1996 Federal Register and 
reiterated in the RED, the Agency has estimated dietary exposure to cryolite 
using reassessed tolerances for all crops (including the proposed tolerances 
for potatoes) 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 1-6, 
0.015 mg/kg/day for children 7-12, and 0.028 mg/kg/day for nursing females 13+ 
years. For the highest exposed subgroup (females 20 years old and over), the 
Agency estimated exposure of 0.038 mg/kg/day (61 FR 20781). The Agency 
estimated dietary exposure resulting from the specific use of cryolite on 
potatoes to be approximately 0.00016 mg/kg/day. The Task Force believes that 
these exposure estimates in fact 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 to 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 previously estimated 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 May 8, 1996 Federal Register and reiterated 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. For dietary exposure, EPA has concluded that rather than 
establishing a traditional Reference Dose (RfD), a weight- of-the-evidence 
risk assessment is a more appropriate approach for cryolite. The toxicological 
endpoint of concern for dietary exposure to cryolite is skeletal fluorosis. 
EPA 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 0.038 
mg/kg/day for the highest exposed subgroup (females 20 years old and over). 
The proposed potato tolerances have been estimated by EPA to contribute 
approximately 0.00016 mg/kg/day to total dietary exposure. 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 crops would not include imported foodstuffs.

II. Public Record

A record has been established for this notice under docket control number [PF-
712] (including comments and data submitted electronically as described 
below). A public version of the 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 public record is located in Room 1132 of the 
Public Response and Resources Branch, Field Operations Division (7506C), 
Office of Pesticide Programs, Environmental Protection Agency, Crystal Mall 
#2, 1921 Jefferson Davis Highway, Arlington, VA.

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. 

The official record for this rulemaking, as well as the public version, as 
described above will be kept in paper form. Accordingly, EPA will transfer all 
comments received electronically into printed, paper form as they are received 
and will place the paper copies in the official rulemaking record which will 
also include all comments submitted directly in writing. The official 
rulemaking record is the paper record maintained at the address in "ADDRESSES" 
at the beginning of this document.

List of Subjects

Environmental protection, Administrative practice and procedure, Agricultural 
commodities, Pesticides and pests, Reporting and recordkeeping requirements.

Dated: February 24, 1997.

Peter Caulkins,
Acting Director, Registration Division, Office of Pesticide Programs. 

[FR Doc. 97-6015 Filed 3-11-97; 8:45 am]