Docket Number: EPA-HQ-OPP-2011-0173 

www.regulations.gov 

Cryolite Summary Document 

Registration Review: Initial Docket 

 March 2011 
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TABLE OF CONTENTS 

 Page # 

I. Preliminary Work Plan (PWP) 4 

II. Fact Sheet 12 

III. Summary of Data Gaps 18 

________________________________________ 

Please Note 

This Preliminary Work Plan and Fact Sheet summarize the Environmental Protection Agency's 

current position based on the following documents: 

1. Registration Review – Preliminary Problem Formulation for the Ecological Risk and 

Drinking Water Exposure Assessments for Cryolite. March 8, 2011. 

2. Cryolite. Human Health Scoping Document in Support of Registration Review. March 

16, 2011. 

3. Sulfuryl Fluoride – Revised Human Health Risk Assessment for Fluoride to Incorporate 

New Hazard and Exposure Information. January 7, 2011. Available in the sulfuryl 

fluoride docket EPA-HQ-OPP-2005-0174. 

4. Updated Review of Cryolite Incident Reports. November 30, 2010. 

5. Chemical Profile for Registration Review: Cryolite. November 10, 2010. 

6. Screening Level Use Analysis (SLUA) for Cryolite. June 21, 2010. 

7. Appendix A for Cryolite. September 2, 2010. 

Additional supporting documents for cryolite may be found in the cryolite registration review 

docket located on the internet at: www.regulations.gov
4

I. Preliminary Work Plan – Cryolite 

Introduction:

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides sold or distributed in the United States generally must be registered by the 

Environmental Protection Agency (EPA), based on scientific data showing that they will not 

cause unreasonable risks to human health or the environment when used as directed on product 

labeling. The registration review program is intended to make sure that, as the ability to assess 

risk evolves and as policies and practices change, all registered pesticides continue to meet the 

statutory standard of no unreasonable adverse effects to human health or the environment. 

Changes in science, public policy, and pesticide use practices will occur over time. Through the 

registration review program, the Agency periodically reevaluates pesticides to make sure that as 

change occurs, products in the marketplace can be used safely. Information on this program is 

provided at: http://www.epa.gov/oppsrrd1/registration_review/. 

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The Agency will consider benefits information and data as required by FIFRA. The 

public phase of registration review begins when the initial docket is opened for each case. The 

docket is the Agency’s opportunity to state what it knows about the pesticide and what additional 

risk analyses and data or information it believes are needed to make a registration review 

decision. After reviewing and responding to comments and data received in the docket during 

this initial comment period, the Agency will develop and commit to a final work plan and 

schedule for the registration review of cryolite. 

Cryolite is a naturally-occurring mineral of sodium aluminum fluoride, and is part of the 

inorganic fluorine chemical family. Products included in this registration review case include 

both natural and synthetic sources. Cryolite is registered for use in agricultural settings on 

various fruits and vegetables, as well as for some uses on ornamental plants. There are no 

residential or public recreational uses of cryolite. 

Furthermore, cryolite's toxicity is attributed to its dissociation into fluoride ions in the 

environment. The only residue of concern for the tolerance expression for cryolite is fluoride. 

Therefore, all cryolite food tolerances are expressed in terms of fluoride. Cryolite was subject to 

a Reregistration Eligibility Decision (RED), which was completed in June 1996. The 1996 RED 

evaluated data on both cryolite and fluoride. Cryolite tolerances were reassessed in 1997 in 

conjunction with a registration action. 

On January 19, 2011, EPA published a proposed order granting objections to tolerances and a 

stay request with regard to sulfuryl fluoride and fluoride tolerances promulgated in 2004 and 

2005 under section 408(d) of the Federal Food, Drug, and Cosmetic Act (FFDCA) (FRL–8857–

9). The objections and stay request were filed by the Fluoride Action Network (FAN), the 
5

Environmental Working Group (EWG), and Beyond Pesticides. The Objectors argue that the 

fluoride tolerances should not have been established by EPA because aggregate exposure to 

fluoride is unsafe under FFDCA section 408. EPA is currently seeking public comment on all 

aspects of the proposed resolution of objections, including the scientific evaluations and the 

flouride aggregate risk assessment (EPA Docket No. EPA–HQ–OPP–2005–0174). This action is 

relevant to cryolite because, like sulfuryl fluoride, cryolite breaks down into fluoride. The 

aggregate fluoride risk assessment, which served as the basis for EPA’s proposed order to 

withdraw the sulfuryl fluoride tolerances, considered all sources of fluoride exposure including 

fluoride exposure as a result of the use of cryolite. Therefore, this action may affect cryolite’s 

registration review timeline and decision. 

Anticipated Risk Assessment and Data Needs:

The Agency anticipates updating and revising the ecological risk assessment (including an 

endangered species risk assessment) and the human health risk assessment for all uses of 

cryolite. Below is a summary of the issues relevant to the registration review of cryolite and the 

data the Agency anticipates requiring: 

Ecological Risk: 

• The most recent ecological risk assessment for cryolite was completed in 1996 in support 

of the RED. 

• The Agency has not conducted an ecological risk assessment that supports a complete 

endangered species determination for cryolite. The ecological risk assessment planned 

during registration review will allow the Agency to determine whether cryolite’s use has 

“no effect” or “may affect” federally listed threatened or endangered species (listed 

species) or their designated critical habitats. When an assessment concludes that a 

pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency 

will consult with the U.S. Fish and Wildlife Service (FWS) and/or National Marine 

Fisheries Service (NMFS) (the Services), as appropriate. 

• The Agency does not anticipate requiring environmental fate data during registration 

review. However, the Agency anticipates requiring the following environmental effects 

data for use in conducting a complete ecological risk assessment, including an 

endangered species assessment, for all uses: 

o Guideline (GLN) No. 850.2100 – Avian Oral Toxicity (Passerine) 

o GLN No. 850.1025 – Acute Toxicity Estuarine/Marine Organisms (Oyster) 

o GLN No. 850.1075 – Freshwater Fish Toxicity (Estuarine/Marine) 
6

o GLN No. 850.4100 – Nontarget Area Phytotoxicity Tier II, Seedling Emergence1 

o GLN No. 850.4150 – Nontarget Area Phytotoxicity Tier II, Vegetative Vigor1 

GLN No. 850.4400 – Nontarget Area Phytotoxicity Tier II, Aquatic Plant Growth 

(Vascular Plants) 1

o GLN No. 850.5400 – Nontarget Area Phytotoxicity Tier II, Aquatic Plant Growth 

(Algal Plants) 1

• Please refer to Registration Review – Preliminary Problem Formulation for the 

Ecological Risk and Drinking Water Exposure Assessments for Cryolite, March 8, 2011, 

located in the docket, for a detailed discussion of these anticipated risk assessment and 

data needs. 

Human Health Risk:

• A comprehensive human health risk assessment was completed in 1996 in support of 

reregistration, which assessed dietary (food and water) and occupational exposures. The 

1996 RED evaluated data on both cryolite and fluoride because cryolite’s toxicity is 

attributed to its dissociation into fluoride ions. 

• On January 7, 2011, the Office of Pesticide Programs and the Office of Water completed 

an aggregate risk assessment for all dietary exposure sources of fluoride in food and 

drinking water, including the pesticide cryolite and sulfuryl fluoride. 

• Based on an endpoint of severe dental fluorosis, exposures for some sub-populations 

exceeded the Agency’s level of concern particularly for children living in areas with high 

levels of naturally-occurring fluoride in their drinking water. The Agency is currently 

seeking comment on this risk assessment (EPA Docket No. EPA-HQ-OPP-2005-0174). 

• Since fluoride is the only residue of concern from cryolite applications, the Agency will: 

1) review all the comments received on the January 2011 fluoride aggregate risk 

assessment; 2) determine if a new aggregate risk assessment for cryolite is needed; and 3) 

determine whether cryolite meets the FFDCA safety standard. The registration review 

timeline for cryolite, described on page 8 of this document, is contingent upon the 

Agency’s safety standard determination for cryolite following the review of comments 

received on the January 2011 fluoride aggregate risk assessment. 

• Currently, there are no registered uses for cryolite that would result in residential 

exposure. However, residential bystander inhalation exposures resulting from off-site 

transport (e.g., spray drift) may occur as a result of applications of cryolite. The Agency 

 1

A Tier II study is expected to be required. The DCI expected to be issued will provide that a Tier I plant 

study may be conducted in lieu of a Tier II study with the understanding that any adverse effects observed 

by the Tier I study would necessitate conduct and submission of a Tier II study as well. 
7

is in the process of examining its policies and refining the methods used to complete 

residential exposure assessments. Therefore, the potential need for a bystander inhalation 

risk assessment for cryolite will be examined during registration review. 

• If an applicable endpoint is identified in the anticipated 90-Day Inhalation Toxicity study, 

the Agency intends to conduct a quantitative risk assessment for occupational exposure. 

The Agency is currently evaluating the March 2, 2010 Scientific Advisory Panel (SAP) 

final report on issues related to volatilization of pesticides and may, as appropriate, 

develop policies and procedures to identify whether to incorporate post-application 

inhalation exposure into the Agency’s risk assessments, and methods to assess postapplication inhalation exposure. If new policies or procedures are implemented, the 

Agency would anticipate revisiting the need for a quantitative occupational postapplication inhalation exposure assessment for cryolite. 

• Since the residue of concern for cryolite applications is fluoride, tolerance levels and 

residue definition may need to be modified or revoked in the future based on a 

determination of fluoride aggregate risks and whether cryolite meets the FFDCA safety 

standard. 

• For a discussion of tolerances, see Cryolite: Registration Review Scoping Document for 

Human Health Assessments, dated March 16, 2011. 

• The toxicity database is complete except for the following studies, which the Agency 

anticipates requiring in order to conduct a complete human health assessment: 

o GLN No. 870.3465 - 90-Day Inhalation Toxicity 

o GLN No. 870.7800 - Immunotoxicity 

• Please refer to the Cryolite. Human Health Scoping Document in Support of Registration 

Review, March 16, 2011, located in the docket, for a detailed discussion of the anticipated 

risk assessment and data needs for human health. 

Endocrine Disruptor Screening Program:

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its most recent registration decision, EPA reviewed these data and 

selected the most sensitive endpoints for relevant risk assessment scenarios from the existing 
8

hazard database. However, as required by FFDCA section 408(p), cryolite is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. Cryolite is not 

among the group of 58 pesticide active ingredients on the initial list to be screened under the 

EDSP. EPA may issue future EDSP orders/data call-ins as part of registration review requiring 

the submission of EDSP screening assays for cryolite. This action will be contingent on the 

regulatory safety determination of cryolite following the review of comments on the January 

2011 fluoride aggregate risk assessment. For further information on the status of the EDSP, the 

policies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 

screening battery, please visit our website: http://www.epa.gov/endo/. 

Timeline:

EPA has created the following estimated timeline for the completion of the cryolite registration 

review. It should be noted that this timeline will be contingent on the regulatory safety 

determination of cryolite following the review of comments on the January 2011 fluoride 

aggregate risk assessment. 

Registration Review for Cryolite– Projected Registration Review Timeline 

Activities Estimated Date 

Opening the Docket 

Open Docket and Public Comment Period 2011 – March 

Close Public Comment 2011 – May 

Case Development 

Final Work Plan 2011 – August 

Issue DCI 2012 – April – June 

Data Submission 2014 – April – June 

Open Public Comment Period for Draft Risk Assessments 2015 – Oct. – Dec. 
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Registration Review for Cryolite– Projected Registration Review Timeline 

Close Public Comment Period 2016 – Jan. – March 

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review 

Decision 

 2016 – April – June 

Close Public Comment Period 2016 – July – Sept. 

Registration Review Decision and Begin Post-Decision Follow-up 2017 

Total (years) 6 

Guidance for Commenters:

The public is invited to comment on EPA’s preliminary work plan and rationale. The Agency 

will carefully consider all comments as well as any additional information or data provided in a 

timely manner prior to issuing a final work plan (FWP) for cryolite. 

Trade Irritants:

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. Growers and 

other stakeholders are asked to comment on any trade irritant issues resulting from lack of 

Maximum Residue Limits (MRLs) or disparities between U.S. tolerances and MRLs in key 

export markets, providing as much specificity as possible regarding the nature of the concern. 

Water Quality:

Neither cryolite nor fluoride are identified as a cause of impairment for any water bodies listed as 

impaired under section 303(d) of the Clean Water Act2. In addition, no Total Maximum Daily 

Loads (TMDL) have been developed for cryolite3

. More information on impaired water bodies 

and TMDLs can be found on the Agency’s website4

. The Agency invites submission of water 

quality data for this pesticide. To the extent possible, data should conform to the quality 

standards in Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired 

Water Body and Other Water Quality Data in OPP’s Registration Review Risk Assessment and 

Management Process5

 in order to ensure they can be used quantitatively or qualitatively in 

pesticide risk assessments. 

Environmental Justice:

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

 

2 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 3 http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_group_name=PESTICIDES 4 http://www.epa.gov/owow/tmdl/

5 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
10

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to cryolite, compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population. 

Other Information:

Stakeholders are also specifically asked to provide information and data that will assist the 

Agency in refining the risk assessments, including any species-specific ecological effects 

determinations. The Agency is interested in receiving the following information: 

1. confirmation on the following label information; 

a. sites of application 

b. formulations 

c. application methods and equipment 

d. maximum application rates in units related to mass per unit area of treatment 

zone 

e. frequency of application, application intervals and maximum number of 

applications per season 

f. geographic limitations on use 

2. use or potential use distribution (e.g., acreage and geographical distribution of 

relevant crops); 

3. use history; 

4. median and 90th percentile reported use rates (lbs. a.i./acre) from usage data – 

national, state, and county; 

5. application timing (date of first application and application intervals) by crop – 

national, state and county; 

6. sub-county crop location data; 

7. directly acquired county-level usage data (not derived from state level data); 

a. maximum reported use rate (lbs. a.i./acre) from usage data – county 

b. percent crop treated – county 

c. median and 90th percentile number of applications – county 

d. total pounds per year – county 

e. the year the pesticide was last used in the county/sub-county area 

f. the years in which the pesticide was applied in the county/sub-county area 

8. typical interval (days); 

9. state or local use restrictions; 

10. ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian 

and mammalian mortalities) not already reported to the Agency; 

11. pests controlled by cryolite and what are the chemical and non-chemical alternatives 

to cryolite for these pest(s); 
11

12. barriers for adopting chemical and non-chemical alternatives for pest(s) controlled by 

cryolite (e.g., price, relative efficacy, use restrictions, application methods, etc.); 

Next Steps:

After the 60-day comment period closes, the Agency will review and respond to any comments 

received in a timely manner, and then issue its Final Work Plan (FWP) for cryolite. 

 
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II. FACT SHEET 

 

Background Information:

• Cryolite PC code: 075101, CAS No.: 15096-52-3. 

• Registration review case number: 0087. 

• Technical registrants: AMVAC Chemical Company; United Phosphorous, Incorporated; 

and Gowan Company. 

• First registered for use in the U.S. in 1957. 

• The RED for cryolite was completed in June, 1996. 

• Cryolite product reregistration is complete, and the mitigation specified in the 1996 RED 

is on current labels. 

• Cryolite tolerances were reassessed in December 5, 1997 in conjunction with a 

registration action (62 FR 64294-64301). 

• There are currently four end-use products and two technical products registered. 

• There are multiple tolerances for use of cryolite in or on food crops under 40 CFR § 

180.1045. 

• Pesticide Re-evaluation Division Chemical Review Manager: Molly Clayton, 

clayton.molly@epa.gov.

• Registration Division Contact: Venus Eagle, eagle.venus@epa.gov. 

Use & Usage Information: (For additional details, please refer to the Appendix A, SLUA, and 

Chemical Profile documents in the cryolite docket.) 

• Cryolite is an inorganic fluorine compound registered for use as an insecticide and used 

primarily on raisins and table grapes to control leafrollers, leaffolders, worms, and mites.

• Cryolite is formulated as bait/solid, wettable powder/dust, and dust and dry flowable. It 

may be applied as a broadcast foliar spray in early summer and late spring, as 

chemigation with sprinkler irrigation, and as a dust or spray with aircraft.

• The agricultural usage for cryolite from 1998-2008 averaged almost 2 million pounds 

active ingredient for use in about 300,000 acres per year. 

• From 1998-2008, the largest markets in terms of total pounds of active ingredient applied 

were: raisin grapes (71%), table grapes (12%), and wine grapes (9%). 

Recent and Pending Actions:

• On January 19, 2011, EPA published a proposed order granting objections to tolerances 

and a stay request with regard to sulfuryl fluoride and fluoride tolerances promulgated in 

2004 and 2005 under section 408(d) of the Federal Food, Drug, and Cosmetic Act 

(FFDCA) (FRL–8857–9). The objections and stay request were filed by the Fluoride 

Action Network, the Environmental Working Group, and Beyond Pesticides. The 

Objectors argue that the fluoride tolerances should not have been established by EPA 

because aggregate exposure to fluoride is unsafe under FFDCA section 408. EPA is 
13

currently seeking public comment on all aspects of the proposed resolution of objections, 

including the scientific evaluations and the aggregate risk assessment (EPA Docket No. 

EPA–HQ–OPP–2005–0174). 

Ecological Risk Assessment Status:

The following are key findings of the most recent ecological risk assessment for cryolite. Please 

refer to the Registration Review – Preliminary Problem Formulation for the Ecological Risk and 

Drinking Water Exposure Assessments for Cryolite, March 8, 2011, located in the docket, for a 

detailed discussion of the ecological risk assessment. 

Environmental Fate: 

• Cryolite is a naturally-occurring mineral; however, most present day supplies of cryolite 

pesticide products are synthetically produced. Open-literature data were used in 

conjunction with registrant submitted data in the 1996 ecological assessment to address 

the environmental chemistry of cryolite. The fate of the elemental components in cryolite 

(Na, Al, and F) is dependent on the natural biogeochemical cycles influenced by the soil 

chemical and mineralogical properties. 

Risk Estimates: 

• While some acute avian and mammalian risk quotients (RQs) exceeded the Agency’s 

level of concern (LOC) in the 1996 assessment, risk to birds and mammals was not 

expected from any registered use of cryolite based on the likelihood of the species to 

receive significant dietary exposure at the anticipated low exposure levels. Similarly, 

risks to terrestrial invertebrates and plants (i.e., foliage) were not expected. 

• In the 1996 assessment, risk to aquatic organisms was not quantitatively assessed. 

Ground or surface water effects were expected to be negligible. No significant difference 

in the accumulation of aluminum or fluoride moieties in plants or animals was expected 

to occur.

• There is sufficient information to characterize cryolite as practically nontoxic to honey 

bees based on data evaluated from an acute bee contact study. Cryolite’s insecticidal 

mode of action requires ingestion and non-target terrestrial invertebrates are not expected 

to be sensitive to this pesticide via a contact route of exposure. Additionally, insects with 

piercing/sucking mouthparts (including bees) are not expected to be affected by cryolite 

via an oral route because they cannot ingest crystals. 

Human Health Risk Assessment Status:

The following are key findings of the most recent human health risk assessments for cryolite. 

Please refer to the Cryolite. Human Health Assessment Scoping Document in Support of 
14

Registration Review, March 16, 2011, located in the docket, for a detailed discussion of the 

human health risk assessment. 

• The most recent human health risk assessment for cryolite was completed in 1996 in 

support of reregistration. An aggregate risk assessment that included contributions from 

all sources of fluoride, including exposures from cryolite, was completed in January 

2011. 

Hazard Characterization: 

• The 1996 RED evaluated data on both cryolite and fluoride because cryolite's toxicity is 

attributed to its dissociation into fluoride ions. Data evaluated included guideline toxicity 

studies with cryolite, carcinogenicity studies with fluoride, and assessments by several 

government agencies on fluoride in drinking water. 

• Currently, severe dental fluorosis, including enamel pitting and other effects, is the effect 

of concern from dietary exposure. The Office of Water has recently completed a 

benchmark dose analysis in order to select a point of departure based on severe dental 

fluorosis from exposure to fluoride. 

• Dental lesions in rats and mice cryolite toxicity studies were due to enamel fluorosis and 

included effects such as attrition, deformity, mottling, and degeneration. Fluoride can 

also accumulate in bone, and increased bone density in rats after treatment with cryolite 

has been noted in toxicity studies. 

• The recent aggregate risk assessment for fluoride included an analysis for potential 

sensitivity of children to fluoride. Given the relative completeness of the fluoride 

toxicology database; the use of a child-specific endpoint (i.e., the most sensitive effect 

and well-documented outcome in the literature); the data indicating a U-shaped doseresponse curve for oral health; and the understanding of the potential exposures to 

fluoride, the Agency reduced the FQPA Safety Factor for fluoride to 1X. 

• The Agency did not require a dermal toxicity study for its 1996 reregistration decision. 

Given the chemical properties of parent cryolite and degradate (fluoride ions), the 

Agency considered dermal absorption unlikely. 

• As it is well-known that cryolite dissociates into fluoride, the Agency did not require a 

metabolism study. 

 

• Cryolite was classified as “not classifiable as to human carcinogenicity.” 

Dietary (Food and Water): 

• The Agency has recently completed a dietary exposure assessment for all sources of 
15

fluoride in food and drinking water, including the pesticides cryolite and sulfuryl 

fluoride. 

• Monitoring data were used to account for residues of fluoride as a result of cryolite 

application; residues in grapes and raisins were higher than other crops (consistent with 

the usage assessment). 

Residential: 

 

• Cryolite is not registered for use in residential or public recreational settings. Therefore, 

a standard residential exposure risk assessment was not conducted for the 1996 RED.

Aggregate: 

• In January 2011, the Agency completed an aggregate risk assessment for exposure to 

fluoride, including the following sources of fluoride: dietary exposure from the pesticides 

cryolite and sulfuryl fluoride; water exposure from naturally occurring sources of fluoride 

in the environment as well as the intentional addition of fluoride to drinking water 

sources to prevent dental caries; incidental ingestion of fluoride while brushing teeth; and 

soil ingestion by children. 

• This aggregate assessment identified some sub-populations whose exposure exceeded the 

Agency’s level of concern for fluoride, particularly children living in areas with high 

levels of naturally-occurring sources of fluoride in their drinking water. 

Occupational: 

• In the most recent occupational risk assessment (1996), no dermal or inhalation 

toxicological endpoints were identified; therefore, a quantitative occupational risk 

assessment for occupational exposures was not conducted. 

• Toxicity via the dermal route was not expected due to the ionic nature of cryolite. 

Cumulative: 

• Unlike other pesticides for which EPA has followed a cumulative risk approach based on 

a common mechanism of toxicity, EPA has not made a common mechanism of toxicity 

finding as to cryolite and any other substances. As described in the aggregate section 

above, fluoride is a degradate of cryolite, and has been previously assessed. For the 

purposes of this registration review assessment of data needs, EPA has not assumed nor 

determined that cryolite has a common mechanism of toxicity with other substances. For 

information regarding EPA’s efforts to determine which chemicals have a common 

mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the 

policy statements released by EPA’s Office of Pesticide Programs concerning common 
16

mechanism determinations and procedures for cumulating effects from substances found 

to have a common mechanism on EPA’s website at: 

http://www.epa.gov/pesticides/cumulative/. If, in the future, the Agency determines that 

new information on cryolite is available that could potentially impact a cumulative risk 

assessment and result in a risk of concern, the Agency will revisit the need for a 

cumulative risk assessment. 

Incidents:

Ecological:

• The Ecological Incident Information System (EIIS) was consulted for reports of 

ecological incidents associated with cryolite. There is one 1992 reported incident in 

Delaware in which a wettable powder containing cryolite was sprayed on potatoes. One 

thousand fish were killed from the runoff. The certainty code is unlikely and the legal 

status of the particular use in relation to the product label is unknown. 

Human Health: 

• No cryolite poisoning incidents were reported in the Office of Pesticide Programs 

Incident Data System (IDS) since 2002. 

Tolerances and International Harmonization: 

• The residue of concern for the tolerance expression for cryolite is fluoride. All food 

tolerances are expressed in terms of fluoride. Although uses of cryolite are registered for 

animal feed commodities, the Agency had previously determined that there is no 

reasonable expectation of finite residues in livestock; therefore, livestock commodity 

tolerances are not needed. 

• No maximum residue limits (MRLs) have been established by Codex or Canada for 

residues of cryolite or fluoride. Mexico adopts US tolerances and/or Codex MRLs for its 

export purposes. 

Data Call-In Status: 

• Generic data call-ins (GDCI-075101-16283, GDCI-075101-15979, and GDCI-075101-

16944) were issued in January 1980, January 1991, and November 1996, respectively. 

All of these data requirements have been fulfilled. 

Labels: 

 

• The labels for cryolite can be obtained from the Pesticide Product Label System (PPLS) 

website at: http://oaspub.epa.gov/pestlabl/ppls.home. 
17

Cryolite Registrations as of March 4, 2011 

Registration No. Product Name Company Name 

5481-132 Cryolite 93 AMVAC Chemical 

Corporation 

10163-41 PROKIL Cryolite 96 Gowan Company 

10163-185 PROKIL Cryolite Water Dispersable Granular Gowan Company 

10163-225 Gowan Cryolite Bait Gowan Company 

10163-242 PROKIL Cryolite 75 Dust Gowan Company 

10163-243 PROKIL Cryolite 50 Dust Gowan Company 

70506-172 Kryocide Insecticide United Phosphorus, Inc. 

 
18

III. Summary of Data Gaps 

The table below summarizes the anticipated data requirements for cryolite. 

Guideline 

Number Study Title Test 

Material 

Estimated 

Timeframe 

(Measured 

in Months) 

850.2100 Avian Oral Toxicity (Passerine) TGAI6 12 

850.1075 Freshwater Fish Toxicity (Estuarine/Marine) TGAI 12 

850.1025 Acute Toxicity Estuarine/Marine Organisms (Oyster) TGAI 12 

850.4100 Nontarget Area Phytotoxicity Tier II, Seedling 

Emergence7 TGAI 12 

850.4150 Nontarget Area Phytotoxicity Tier II, Vegetative Vigor7

 TGAI 12 

850.4400 Nontarget Area Phytotoxicity Tier II, Aquatic Plant 

Growth (Aquatic Vascular Plants) 7 TGAI 12 

850.5400 Nontarget Area Phytotoxicity Tier II, Aquatic Plant 

Growth (Algal Plants) 7 TGAI 12 

870.3465 90-Day Inhalation Toxicity TGAI 24 

870.7800 Immunotoxicity TGAI 12 

 

6

 Technical Grade Active Ingredient (TGAI). 

7

 A Tier II study is expected to be required. The DCI expected to be issued will provide that a Tier I plant study 

may be conducted in lieu of a Tier II study with the understanding that any adverse effects observed by the Tier I 

study would necessitate conduct and submission of a Tier II study as well. The purpose of a Tier II study is to 

establish both a definitive No Observed Adverse Effect Concentration (NOAEC), or alternatively, a concentration at 

which there is a 5% observed inhibition effect (IC05) to be used in a risk assessment and effects determination for 

endangered or threatened species (listed species), and a definitive IC25 (concentration at which there is a 25% 

observed inhibition effect) for assessing risk to non-listed nontarget plants. If any adverse effects are observed in a 

Tier I study and neither a definitive NOAEC nor a definitive IC05 value is available, then the Agency may have to 

presume in its effects determination, that cryolite "may affect" and is “likely to adversely affect” listed plant species.