Document ID: EPA-HQ-OPP-2011-0173-0002
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-03-30T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C., 20460
                                   OFFICE OF
                   CHEMICAL SAFETY AND POLLUTION PREVENTION
                                       
                                                                               

March 8, 2011

MEMORANDUM

Subject:	Registration Review  -  Preliminary Problem Formulation for the Ecological Risk and Drinking Water Exposure Assessments for Cryolite (PC Code 075101; DP Barcode 383606) 

To:		Molly Clayton, Risk Manager Reviewer 
		Risk Management and Implementation Branch 3 
      Pesticide Re-evaluation Division

From:		Pamela Hurley, Ph.D., Toxicologist 
		James Hetrick, Ph.D., Senior Science Advisor
		Melissa Panger, Ph.D., Senior Biologist
		Environmental Risk Branch 3
		Environmental Fate and Effects Division
		Office of Pesticide Programs

Through:	Dana Spatz, Branch Chief
		Environmental Risk Branch 3
		Environmental Fate and Effects Division
		Office of Pesticide Programs

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem formulation (attached) for the ecological risk, environmental fate, endangered species, and drinking water assessments to be conducted as part of the Registration Review of the insecticide, cryolite.  Because cryolite is an inorganic pesticide, the ecological risk and exposure assessment methodologies must account for the specific properties of this compound.  This document is intended to provide an overview of what is currently known regarding the environmental fate and ecological effects associated with cryolite and outlines uncertainties regarding attributes of the parent compound and its elemental constituents.  It describes the preliminary ecological risk hypothesis and the processes that will be used during the completion of drinking water and ecological risk assessments in support of Registration Review.  

              Office of Chemical Safety and Pollution Prevention
				
                          Problem Formulation for the
            Ecological Risk and Drinking Water Exposure Assessments
                   in Support of the Registration Review of 
                                   Cryolite

                                       
                                       
                                       
                                       
                          Cryolite (CAS 102851-06-9)
Sodium aluminofluoride or sodium aluminum fluoride or sodium hexafluoroaluminate

Prepared by:
Pamela M. Hurley, Ph. D., Toxicologist
James Hetrick, Ph.D, Senior Science Advisor
Melissa Panger, Ph.D., Senior Biologist
U. S. Environmental Protection Agency
Office of Pesticide Programs
Environmental Fate and Effects Division
Environmental Risk Branch 3
1200 Pennsylvania Ave., NW
Mail Code 7507P
Washington, DC20460
Reviewed by:
Dana Spatz, Branch Chief

Date
March 8, 2011

                                       
                               Table of Contents
                                       
I.  Purpose	4
II. Nature of Regulatory Action	4
A. 	Regulatory History	4
B.	Previous Risk Assessments	5
III. Stressor Source and Distribution	6
A.	Nature of Chemical Stressor	6
B.	Mechanism of Action	7
C.	Overview of Pesticide Usage	7
D.	Environmental Fate and Transport	9
Physical and Chemical Properties of Cryolite	9
Environmental Fate Properties of Cryolite	9
IV. Receptors	10
A.  Effects to Aquatic Organisms	11
B.  Effects to Terrestrial Organisms	13
C.  Adverse Ecological Incidents	14
D.  Ecosystems at Risk	14
V.  Assessment Endpoints	15
VI. Conceptual Model	15
A.  Risk Hypotheses	15
B.  	Diagram	16
Direct Terrestrial Uses	16
VII. Analysis Plan	18
A.	Ecological Risk Assessment	18
Measures of Exposure	18
(1)	Aquatic Exposure Models	18
(2) 	 Terrestrial Exposure Models	18
SIP (Screening Imbibition Program)	19
Measures of Effects	20
B.	Endangered Species	21
C.	Drinking Water Assessment	21
D.	Clean Water Act	22
E.	Anticipated Data Needs	23
Environmental Fate	23
There are no fate data requirements at this time.	23
Environmental Effects	23
Other Information Needs	27

I.  Purpose

The purpose of this problem formulation is to provide a better understanding of the environmental fate and ecological effects of cryolite (CAS Number 15096-52-3; Sodium aluminofluoride or sodium aluminum fluoride or sodium hexafluoroaluminate).  As such, it articulates the purpose and objectives of the risk assessment, evaluates the nature of the problem, and provides a plan for analyzing the data and characterizing the ecological risk.  Additionally, this problem formulation is intended to identify any data gaps, uncertainties, and potential assumptions needed to address those uncertainties in characterizing the ecological risk associated with the registered uses of cryolite.
 
II. Nature of Regulatory Action

The Food Quality Protection Act of 1996 mandated the EPA to implement a new program for assessing the risks of pesticides, i.e., registration review.  All pesticides distributed or sold in the United States generally must be registered by EPA.  The decision to register a pesticide is based on the consideration of scientific data and other factors showing that it will not cause unreasonable risks to human health, workers, or the environment when used as directed on product labeling.  The Registration Review program is intended to ensure 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 and the environment.  Changes in science, public policy, and pesticide use practices will occur over time.  Through the new Registration Review program, the Agency periodically reevaluates pesticides to ensure that as change occurs, products in the marketplace can be used safely. 
As part of the implementation of the new Registration Review program pursuant to Section 3(g) of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the Agency is beginning its evaluation to determine whether cryolite continues to meet the FIFRA standard for registration.  This problem formulation for the environmental fate and ecological risk assessment chapter in support of the registration review is intended for the initial docket opening for the public phase of the review process. 
      
      A. 	Regulatory History

The 1996 Reregistration Eligibility Decision (RED) states that:

       "Cryolite has been registered in the United States since 1957 for use as an insecticide.  A Registration Standard was issued in June 1983 for all pesticide products containing the active ingredient, cryolite.  This document identified the additional generic data required to support the continued registration of cryolite for terrestrial outdoor food and non-food uses.  The 1983 Registration Standard also specified the product-specific product chemistry and acute toxicity data required for manufacturing use products.  At the time the 1983 Registration Standard was issued, the Agency's data base for cryolite was extremely poor and extensive data gaps existed in all disciplines.  The Agency reviewed all of the data submitted in response to the data requirements outlined in the 1983 Registration Standard and subsequently issued a Final Registration Standard and Tolerance Reassessment (FRSTR) in April 1988.  In the 1988 Registration Standard, the Agency concluded that additional data were required to make a full assessment regarding the continued registration of all uses of cryolite.  Existing data gaps resulted from a determination that certain submitted studies were unacceptable, and changes in data status from "reserved" to "required" based on results of lower tier studies, and/or expanded CFR Part 158 data requirements.  A Data Call-In (DCI) for cryolite was issued in 1990, which required ecological effects, toxicological data and additional residue data to reassess current tolerances for cryolite.  In response to the DCI and Product and Residue Chemistry Update, the basic registrants chose not to support certain registered food uses.  On March 12, 1996, a Generic Data Exemption (GDE) revocation letter was sent to the remaining end-use product registrant, who also opted not to support those same registered food uses.  Amended labels showing the removal of these unsupported uses are required to be submitted within sixty days from the date of issuance of this Reregistration Eligibility Document."  

The 1996 Reregistration Eligibility Decision reflected a reassessment of all data submitted in response to the Registration Standard for cryolite, as well as assessments of data submitted in response to the DCI and Product and Residue Chemistry Update.  The current Registrants for cryolite are Gowan Company and Elf Atochem North America Inc.

      B.	Previous Risk Assessments

The most complete risk assessment on cryolite is the 1996 RED.  The following paragraphs summarize the risk conclusions for the 1996 RED.

Although the risk quotients (RQ's) exceeded the acute LOC for birds for several uses, acute risk to birds was not expected from any registered use of cryolite.  The RED stated: "it is unlikely that birds would receive significant dietary exposure.  Although many bird species will eat grasses, they generally provide a relatively poor quality food when compared with other potential food items.  A more reasonable "worst case" scenario for cryolite ingestion by birds is exemplified by contaminated grapes.  This residue level is much less than 10% of the avian LC50 value (i.e., the criterion for concern about endangered species).  Therefore, it is unlikely that cryolite use poses any significant acute risks to avian species, including those designated as endangered."

Avian reproduction data are not available for cryolite.  The RED stated the following concerning risk to birds following chronic exposure:  "Ordinarily, any pesticide with multiple applications generates a concern for chronic risk to birds.  Although most cryolite uses allow for multiple applications, chronic risk is not a concern in this case as cryolite is not acutely toxic to birds and it is a naturally occurring mineral that is soluble in water (i.e., 400 - 1200 ppm).  In view of the above, it is unlikely that cryolite residues will accumulate on foliage.  Any significant rainfall or irrigation would also serve to decrease the probability of accumulation on foliage."

Although for some uses the RQ's exceeded the acute LOC for mammals, the RED stated that: "it should be noted that these calculations are estimates based on the value LD50> 1500 mg/kg, which is the "lowest" value available.  The data also show longer studies (e.g., 28-day and 3-month) with rats, with no mortality at levels as high as 50,000 ppm in the diet.  Based on all the available information, acute risk to small mammals is not expected from the use of cryolite."  For the same reasons listed above in the discussion on birds, chronic risk to mammals was not expected from the cryolite's registered uses.

For terrestrial invertebrates, the RED stated that with an acute contact LD50 of >217 micrograms per bee, cryolite is considered nontoxic to honey bees.  Risk to honey bees is not expected.

The RED stated that terrestrial plant testing (e.g., seedling emergence and vegetative vigor) is required for herbicides that have terrestrial non-residential outdoor use patterns and appear to move off site of application through volatilization (vapor pressure >1.0 x 10[-5]mm Hg at 25°C) or drift (aerial or irrigation), and/or that may have endangered or threatened plant species associated with the site of application.  The above conditions did not apply for cryolite; therefore, plant data was not required.

No risks to endangered species were identified in the RED.

For aquatic organisms, the RED stated that because of the unique nature of cryolite and the fact that it is a naturally occurring mineral, the standard estimated environmental concentration (EEC) calculations are not appropriate for this pesticide.  This conclusion was based upon the fact that in the presence of sufficient water, cryolite is quickly converted to near natural background levels of its constituents.  Any minor chemical imbalances caused by its insecticidal application are expected to be offset by the specific mineral buffering capacity of the environment and self-correcting agricultural practices.  Ground or surface water effects are expected to be negligible, and no significant difference in the accumulation of aluminum or fluoride moieties in plants or animals is expected to occur.  Therefore, the use of cryolite was not expected to present significant risk to aquatic organisms.

III. Stressor Source and Distribution

      A.	Nature of Chemical Stressor

The chemical structure of cryolite (CAS Number 15096-52-3; Sodium aluminofluoride or sodium aluminum fluoride or sodium hexafluoroaluminate) is shown in Figure 1 and additional chemical identification is provided in Table 1.  

                                       

                                       

  Figure 1. Chemical Structure of Cryolite.
   
  Table 1. Chemical Identification of Cryolite.
                                       
                                   Parameter
                                     Value
                               Chemical Name(s)
Sodium aluminofluoride or sodium aluminum fluoride or sodium hexafluoroaluminate
                                  Common Name
                                   Cryolite
                                 Trade Name(s)
                        Kryocide(R), Prokil(R), Cryolite
                       Chemical Abstracts Service (CAS)
                                Registry Number
                                  15096-52-3
                          USEPA Pesticide Code (PC #)
                                    075101
                               Empirical Formula
                                  [Na]3[AlF]6
                                Pesticide Type
                                  Insecticide
                                Chemical Class
                                    Mineral

      B. Mechanism of Action

Cryolite is an inorganic insecticide.  It's mode of action is predominantly a non-specific feeding blocker/stomach poison.  Its exact mechanism of action is not yet well understood.  The 1996 RED states: "Insects with chewing mouthparts digest cryolite's tiny sharp crystals, which lacerate their guts and introduces fluoride ions.  The fluoride ions act to inhibit enzymes containing iron, calcium, and magnesium.  Insects with piercing/sucking mouthparts are not affected by cryolite because they cannot ingest crystals.  Cryolite is reported to have minimal or no effect on beneficial insects, such as bees, predators and parasites."

      C.	Overview of Pesticide Usage

All currently registered uses are listed in Table 2.  Cryolite is registered on 34 different food crops.  It is formulated as bait/solid, dust, water dispersible granule, and wettable powder.  The maximum single cryolite application rate ranges from 8 to 23.04 lbs/A.  The maximum seasonal application rates ranges from 23.04 to 153.6 lbs/A.  Label warnings include drift mitigation language, surface water advisories, and fish toxicity warnings.

Table 2. Summary of Cryolite Registered Uses.

                                       
                                   Crop/Site
                                       
                           Application Type, Method
                                       
                           Maximum Application Rate
                                    (lbs/A)
                                       
                          Maximum Application Number
                         Minimum Retreatment Interval
                                    (days)
                               Maximum Seasonal
                                     Rate
                                    (lbs/A)
                                   Blueberry
                                 Foliar Ground
                                      8 
                                      NS
                                      10 
                                      NS
                                   Broccoli
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     92.16
                                Brussel Sprouts
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     92.16
                                    Cabbage
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                    122.88
                                  Cauliflower
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     92.16
                                    Citrus
                             Foliar/Ground/Aerial
                                     28.8
                                      NS
                                      30
                                     86.4
                                   Collards
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                      10
                                     92.16
                                   Cranberry
                             Foliar/Ground/Aerial
                                     11.52
                                      NS
                                      10
                                     34.56
                                   Cucumber
                             Foliar/Ground/Aerial
                                     11.52
                                      NS
                                      10
                                     46.08
                                   Eggplant
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     61.44
                                  Grapefruit
                             Foliar/Ground/Aerial
                                     18.6
                                      NS
                                      30
                                     83.7
                                    Grapes
                             Foliar/Ground/Aerial
                                      9.6
                                      NS
                                      14
                                     19.2
                                  Kiwi Fruit
                                 Foliar/Ground
                                      9.6
                                      NS
                                      15
                                     38.4
                                   Kohlrabi
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     92.16
                                     Lemon
                             Foliar/Ground/Aerial
                                     18.6
                                      NS
                                      30
                                     83.7
                                    Lettuce
                             Foliar/Ground/Aerial
                                     18.6
                                      NS
                                       7
                                     148.8
                                 Lettuce, Head
                             Foliar/Ground/Aerial
                                     19.2
                                      NS
                                       7
                                     153.6
                                 Leaf Lettuce
                             Foliar/Ground/Aerial
                                     19.2
                                      NS
                                       7
                                     153.6
                                     Lime
                             Foliar/Ground/Aerial
                                     18.6
                                      NS
                                      30
                                     83.7
                                    Melons
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     76.8
                               Melon, Cantaloupe
                             Foliar/Ground/Aerial
                                     14.88
                                      NS
                                       7
                                     59.52
                                  Watermelon
                             Foliar/Ground/Aerial
                                     14.88
                                      NS
                                       7
                                     59.52
                                    Orange
                             Foliar/Ground/Aerial
                                     18.6
                                      NS
                                      30
                                     83.7
                                     Peach
                             Foliar/Ground/Aerial
                                     11.52
                                      NS
                                      10
                                     23.04
                                    Pepper
                             Foliar/Ground/Aerial
                                     11.52
                                      NS
                                       7
                                     23.04
                                    Potato
                             Foliar/Ground/Aerial
                                     11.52
                                      NS
                                       7
                                     92.16
                                    Pumpkin
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     76.8
                                   Raspberry
                                 Foliar/Ground
                                       8
                                      NS
                                      10
                                      NS
                                    Squash
                             Foliar/Ground/Aerial
                                     14.88
                                      NS
                                       7
                                     59.52
                                 Summer Squash
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     76.8
                                 Winter Squash
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     76.8
                                 Strawberries
                                 Foliar/Ground
                                       8
                                      NS
                                      10
                                      NS
                                    Tangelo
                             Foliar/Ground/Aerial
                                     18.6
                                      NS
                                      30
                                     83.7
                                  Tangerines
                             Foliar/Ground/Aerial
                                     18.6
                                      NS
                                      30
                                     83.7
                                    Tomato
                             Foliar/Ground/Aerial
                                     15.36
                                      NS
                                       7
                                     61.44
                            Ornamental Shade Trees
                             Foliar/Ground/Aerial
                                     23.04
                                      NS
                                      NS
                                      NS
                         Ornamental Herbaceous Plants
                             Foliar/Ground/Aerial
                                     23.04
                                      NS
                                      10
                                      NS
                        Ornamental NonFlowering Plants
                             Foliar/Ground/Aerial
                                     23.04
                                      NS
                                      10
                                      NS
                       Ornamental Woody Shrubs and Vines
                             Foliar/Ground/Aerial
                                     23.04
                                      NS
                                      10
                                      NS

      
      D.	Environmental Fate and Transport

      Physical and Chemical Properties of Cryolite

The physicochemical properties of cryolite are shown in Table 3.  
      
   
      Table 3. Physical/Chemical Characteristics of Cryolite.
                                       
                                   Parameter
                                     Value
                                    Source
                            Molecular mass (g/mol)
                                    209.95
                                  Calculated 
                                Vapor pressure
                                Not Applicable
                                    Mineral
                            Henry's Law Constant
                                Not Applicable
                                    Mineral
                               Water solubility
                                    at 25°C
                                    (mg/L)
                                   400-1200 
                                       
                                      Kow
                                Not Applicable
                                    Mineral
                                    Log Kow
                                Not Applicable
                                    Mineral

      Environmental Fate Properties of Cryolite

Cryolite is a naturally occurring mineral; however, most present day supplies of cryolite pesticide products are synthetically produced.  Because cryolite is an inorganic substance, the complement of environmental fate studies normally required for registration of organic chemicals is not appropriate.  Therefore, open-literature data in conjunction with registrant submitted data were used to address the environmental chemistry of cryolite.  No additional fate data were required at the time of the 1996 RED (USEPA, 1996; DP Barcode D216315).

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.  The maximum seasonal application of cryolite is 153.6 lbs/A.  The relative contribution of elemental components from cryolite applications to soil are shown in Table 4.  The maximum seasonal application of cryolite is not expected to exceed average elemental soil concentrations of Al, F, and Na.

Table 4. Relative contribution of elemental components from cryolite application to soil.  
                             Elemental Components
                                   Elemental
                                   Fraction
                      Elemental Maximum Application Rate
                                  (lbs/A)[1]
                      Elemental Maximum Application Rate
                                  (mg/kg)[2]
                    Average Elemental Concentration in Soil
                                    (mg/kg)
                                      Al
                                     0.13
                                     19.97
                                     9.985
                                     71000
                                       F
                                     0.55
                                     84.48
                                     42.24
                                      200
                                      Na
                                     0.32
                                     49.15
                                     24.58
                                     6300
   1- elemental fraction in cryolite*maximum season cryolite application rate 
   2- assumes 2.0 x 10[6] lbs dry soil per acre; calculated  by lbs/A /2
      
Standard agricultural practices to maintain soil fertility, particularly pH regulation and maintenance of sources of available calcium, insure that extreme excursions in the amounts of aluminum or fluorine species present in some natural environments do not occur.  Although the use of cryolite should have negligible impacts on ground and surface water quality, cryolite applications in acidic soils or aquatic environments may contribute to Al[3+] toxicity in plants and aquatic organisms.  There should be no difference in the accumulation of aluminum or fluorine moieties in plants or animals under most agricultural conditions.

Two environmental fate laboratory studies were submitted to the Agency by registrants.  The study containing hydrolysis information serves only to show that free fluoride concentrations increase with pH, and that in pure or laboratory buffered water, less than half of the total fluorine is usually available in the form of free fluoride ion.  In the hydrolysis study, aluminum speciation with fluoride or hydroxide was not determined, equilibrium constants were not measured, and the results were not compared with those from scientific literature.  The study on leaching and adsorption suggest precipitation of fluoride controlled the adsorption isotherm.

IV. Receptors

Consistent with the process described in the Overview Document (USEPA, 2004), the risk assessment for cryolite will rely on a surrogate species approach.  Toxicological data generated from surrogate test species, which are intended to be representative of broad taxonomic groups, are used to extrapolate to potential effects on a variety of species (receptors) included under these taxonomic groupings.  
      
Acute and chronic toxicity data from studies submitted by registrants along with the available scientific literature are used to evaluate the potential direct and indirect effects of cryolite on aquatic and terrestrial receptors.  Toxicity studies for the technical grade active ingredient (TGAI) and the typical end-use product (TEP) will all be considered in the ecological risk assessment.  Open literature studies are identified using EPA's ECOTOX database, which employs a literature search engine for identifying chemical toxicity data for aquatic life, terrestrial plants, and wildlife.  Research papers accepted into the ECOTOX database are screened using standard procedures to ensure consistent and high quality information. These studies will be considered during the `Analysis' phase of the risk assessment process.  The Incident Data System (IDS), which tracks incident reports submitted to EPA, is used to identify supportive and line of evidence information on exposure of aquatic and terrestrial receptors.  Data from all of these sources can also provide insight into the direct and indirect effects of cryolite on biotic communities (e.g., loss of species that are sensitive to the chemical, and/or changes in structure and functional characteristics of the affected communities). 

A.  Effects to Aquatic Organisms

The available toxicity data cannot differentiate the toxicity of cryolite from the individual elements in cryolite.  Therefore, the toxicity assessment will consider both the available toxicity data on cryolite only and an exploration of toxicity concerns from the introduced aluminum and fluoride elements from cryolite. 

There is sufficient information to characterize cryolite as no more than slightly toxic to freshwater fish (MRID 40094602) and moderately toxic to freshwater invertebrates (MRID 40094602).   

Acute toxicity testing with estuarine/marine organisms and with aquatic plants is required.  Registered uses of cryolite include aerial applications.  Therefore, cryolite may reach estuarine/marine and freshwater environments through drift.  Currently, there is sufficient information to characterize cryolite as no more than slightly toxic to estuarine/marine shrimp (MRID 00073805); however, there are currently no toxicity data available for estuarine/marine mollusks.   Additionally, as discussed above, although there should be no difference in the accumulation of aluminum or fluorine moieties in plants or animals under most agricultural conditions, cryolite applications in acidic soils or aquatic environments may contribute to Al[3+] toxicity in plants and aquatic organisms.  Therefore, data on mollusks and aquatic plants (both vascular and non-vascular species) are required.  

Freshwater and marine fish and invertebrate chronic studies (e.g. early life-stage/life-cycle tests)
are not required because there are currently no registered aquatic uses.  Furthermore, the dissolution of cryolite to form sodium and the aluminum fluoride complex is expected to produce no significant chronic exposure.

Table 5 summarizes the aquatic toxicity endpoints for cryolite. 

Table 5.  Aquatic Toxicity Profile for Cryolite.

                              Assessment Endpoint

                                    Species

                                Toxicity Values
                                       
Toxicity Category[1]
                                   Reference

                                    Comment

Acute Toxicity to Freshwater Fish
Rainbow trout
47 ppm a.i.
Slightly toxic
MRID 40094602
Johnson & Finley 1980
Acceptable
Acute Toxicity to Estuarine/Marine Fish
                        No data available  -  required
Chronic Toxicity to Freshwater Fish
                                 Not required
Chronic Toxicity to Estuarine/Marine Fish

Acute Toxicity to Freshwater Invertebrates
Simocephalus
5.0 ppm a.i.
Moderately toxic
MRID 40094602 Johnson and
Finley, 1980

Supplemental: Simpcephalusis not a recommended test species
Acute Toxicity to Freshwater Invertebrates
Daphnia pulex
10 ppm a.i.
Moderately toxic
MRID 40094602 Johnson and
Finley, 1980
Acceptable
Acute Toxicity to Estuarine/ Marine Invertebrates
Pink shrimp
> 14 ppm a.i.
Slightly toxic
MRID 00073805 Heitmuller, 1975
Supplemental:  Study was conducted to test the limits of solubility; actual EC50 was not determined.  However, this test is not required.
Chronic Toxicity to Freshwater Invertebrates
Daphnia magna
MATC >5.1, <9.9 ppm for survival
Not applicable
MRID 41207701 Battelle, 1989
Supplemental: MATC's for reproduction and growth were not established.  Assay not required (see notes above table)
Chronic Toxicity to Estuarine/Marine Invertebrates
                                 Not required
Toxicity to Aquatic Plants 
                            Vascular aquatic plants
                        No data available  -  required

                          Non-vascular aquatic plants
                                       
N/A = not applicable
1Based on LC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic; >1-10 moderately toxic; >10-100 slightly toxic; >100 practically nontoxic.

B.  Effects to Terrestrial Organisms

Toxicity from exposure to cryolite requires consideration of the toxicity of the individual elements of cryolite.  Toxicity of the introduced elements of cryolite (Al and F) is expected to be washed off food items into the soil.

Cryolite is practically nontoxic to avian species on an acute oral and sub-acute dietary basis (MRIDs 00152375 and 00084001).  Due to dissolution of cryolite in soils and the relative lack of acute toxicity to birds, chronic risk to birds is not expected.  Therefore, avian reproduction studies are not required for this chemical.

The available mammalian data indicate that cryolite is no more than slightly toxic to small mammals on an acute oral basis (MRID 00071392).  As with the chronic avian studies, the chronic mammalian study is not required.

There is sufficient information to characterize cryolite as practically nontoxic to honey bees based on an acute bee contact study (MRID 00036935).  However, 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.  Therefore, an acute oral honey bee study is not being requested at this time.  In the absence of data indicating otherwise, for the cryolite risk assessment, the following will be assumed:  cryolite poses a risk to terrestrial invertebrates that do not have sucking or piercing mouthparts; risks to invertebrates that have sucking or piercing mouthparts are assumed to be low.   

Terrestrial plant testing (seedling emergence and vegetative vigor) is required for pesticides that have terrestrial non-residential outdoor use patterns and appear to move off site of application through volatilization (vapor pressure >1.0 x 10 [-5]mm Hg at 25°C) or drift (aerial or irrigation), and/or that may have endangered or threatened plant species associated with the site of application.  Because cryolite can be aerially-applied, it may move off the site of application through drift.  Additionally, because of the wide number of agricultural uses, there is a potential for endangered and/or threatened species to be in the vicinity of use sites.  Furthermore, as discussed above, although there should be no difference in the accumulation of aluminum or fluorine moieties in plants or animals under most agricultural conditions, cryolite applications in acidic soils may contribute to Al[3+] toxicity in plants.  Therefore, data on terrestrial plants are required.  

Table 6 summarizes the terrestrial toxicity endpoints for cryolite.

Table 6. Terrestrial Toxicity Profile for Cryolite.
Endpoint
                                    Species
                                Toxicity Value 
                             Toxicity Category[1]
                                   Citation
                                  MRID#/Date
                                    Comment
Acute Avian Oral  Toxicity 
Bobwhite quail (Colinusvirginianus)
>2150 mg/kg
Practically nontoxic
00152375
Fletcher, 1984
Acceptable
Subacute Avian Dietary Toxicity 
Bobwhite quail (Colinusvirginianus)
>10,000 ppm.
Practically nontoxic
00084001
Fink, 1975
Acceptable
Chronic Avian
                                 Not required
Acute Mammalian 
Rat (rattusnorvegicus)
>1500 mg/kg
Slightly toxic
00071392
Acceptable
Chronic Mammalian 
                                 Not required
Acute  Terrestrial Invertebrate 

Honey bee (Apismellifera)
>217 ug a.i./bee
Practically nontoxic
00036935 Atkins, 1975
Acceptable; contact study
Terrestrial Plants

Seedling Emergence
Monocots 
                        No data available  -  required

Seedling Emergence
Dicots 
                                       

Vegetative Vigor
Monocots 
                                       

Vegetative Vigor
Dicots 
                                       
1 Categories of acute toxicity to terrestrial animals, avian and mammalian (U.S. EPA, 2004).  LC50 (ppm):< 50 very highly toxic; 50 - 500 highly toxic; 501 - 1000 moderately toxic; 1001-5000 slightly toxic; >5000 practically non-toxic.  LD50 (mg/kg bw): < 10 very highly toxic; 10 - 50 highly toxic; 51 - 500 moderately toxic; 501-2000 slightly toxic; >2000 practically non-toxic.  Toxicity categories for terrestrial plants have not been defined. 
N/A = not applicable

C.  Adverse Ecological Incidents

The Ecological Incident Information System (EIIS version 2.1) was run on 11/10/2010.  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 legality is unknown (incident report number 1000116-001).

D.  Ecosystems at Risk

Cryolite may be applied as a ground spray for a variety of uses, but the most significant uses in terms of environmental exposure are on woody and herbaceous ornamental plantscapes, eugenia and pepper trees, outdoor ornamentals and on food crops (see Table 2).  It can also be applied aerially on specific crops.

The ecosystems potentially at risk are often extensive in scope; therefore, it may not be possible to identify specific ecosystems at risk during the development of a nation-wide ecological risk assessment.  However, in general terms, terrestrial ecosystems potentially at risk include the treated field and immediately adjacent areas that may receive spray drift or runoff.  Areas adjacent to the treated field could include residential areas, cultivated fields, fencerows, hedgerows, meadows, fallow fields, grasslands, woodlands, riparian habitats, and other uncultivated areas.  

Cryolite has the potential to contaminate surface water through spray drift.  Introduced elemental components of cryolite (Na, Al, F) may contaminate surface water through runoff or erosion.  Aquatic ecosystems potentially at risk include water bodies adjacent to, or downstream of the application site.

V.  Assessment Endpoints

The most sensitive toxicity endpoints are used from surrogate test species to estimate treatment-related direct effects on acute mortality and chronic reproductive, growth, and survival assessment endpoints.  Surrogate aquatic organisms include freshwater and estuarine/marine fish and invertebrates, and surrogate terrestrial animal species include birds and mammals.  These tests include short-term acute, sub-acute, and reproduction studies and are typically arranged in a hierarchical or tiered system that progresses from basic laboratory tests to applied field studies.

For plants in terrestrial and semi-aquatic environments, the screening assessment endpoint is the perpetuation of populations of non-target species (crops and non-crop plant species).  When data are available, endpoints assessed include emergence of seedlings and vegetative vigor. 

VI. Conceptual Model

A.  Risk Hypotheses

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in assessment endpoints) and may be based on theory and logic, empirical data, mathematical models, or probability models (USEPA, 2004).  For this assessment, the risk is stressor-initiated, where the stressor is the release of cryolite to the environment.  The following risk hypothesis is presumed for this screening-level assessment:

      When used in accordance with current labels, cryolite can move off-site via spray drift and expose non-target organisms.  Additionally, individual elements in cryolite (Al, F, and Na) can move with runoff (both dissolved phase and with eroded sediment) and expose non-target organisms.  Application to foliar surfaces and soil may also result in exposure to non-target organisms.  These potential exposure pathways may result in adverse effects on the survival, growth, and/or reproduction of non-target terrestrial and aquatic organisms, including Federally-listed threatened and endangered species.

      B.  	Diagram

      Direct Terrestrial Uses

The environmental fate properties of cryolite indicate that it may reach terrestrial and aquatic environments as depicted in the conceptual diagram presented in Figure 3.  It is also important to address the exposure of introduced Al[3+] and F[-] formed through the dissolution of cryolite. 

Source/
Transport Pathways 
                                Volatilization/
                                Wind Suspension
                               Direct Deposition
                               Runoff / Erosion
                                   Leaching 
                          (infiltration percolation)
Source/ Exposure Media

                               Terrestrial Food
                      Residues (foliage, fruit, insects)
                         Receiving Water Body/Sediment
                                  Groundwater
                           Irrigation water on crops
Exposure
Route
Receptors
                            Terrestrial Vertebrates
            Birds, Mammals, Reptiles, Terrestrial Phase Amphibians
                                Aquatic Plants
                             Aquatic Invertebrates
                                and Vertebrates
                           Insectivorous Vertebrates
                               Birds and Mammals
Attribute
Changes
                  Plant Population Reduced population growth
                   Individual Vertebrates and Invertebrates
                               Reduced survival
                                Reduced growth
                             Reduced reproduction

                                  Spray Drift
                               Uptake/Adsorption
                                Gill/Integument
                                   Ingestion
                              Individual Animals
                               Reduced survival
                                Reduced Growth
                             Reduced Reproduction
                              Individual Animals
                               Reduced survival
                                Reduced growth
                             Reduced reproduction
                Dissolution in soil to form Al[3+], F[-], Na[+]
                      Cryolite Spray Application to Crops
Figure 2. Conceptual Model for Exposure and Effects of Cryolite and the Individual Elements of Cryolite.       
VII. Analysis Plan

During Registration Review, pesticide ecological risk assessments will follow the Agency's Guidelines for Ecological Risk Assessment, will be consistent with the paper titled "Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S. Environmental Protection Agency" ("Overview Document") (January 2004), and will be done in accordance with Section 7 of the Endangered Species Act.  Modifications in exposure assessments will be required to account for the contribution of introduced elements in cryolite (Al, F, Na) and their impact on ambient concentrations of Al, F, Na in soil and aquatic environments.
      
      A.	Ecological Risk Assessment

      Measures of Exposure

In order to estimate risks of cryolite exposure to aquatic and terrestrial environments, all exposure modeling and resulting risk conclusions will be made based on maximum application rates, application methods, and any mitigation measures specifically indicated on the labels.     

         (1) Aquatic Exposure Models

Because cryolite will undergo dissolution to form Na+ and AlF6[-][3], standard exposure modeling is not appropriate.  The aquatic exposure modeling will address the environmental chemistry of Al[3+], F[-], Na[+] from cryolite in aquatic and terrestrial environments.  Tier II Pesticide Root Zone Model- Exposure Analysis Modeling System (PRZM/EXAMS can be used to estimate the concentration of introduced Al[3+], F[-], and Na[+] in surface water.  Chemical equilibria modeling will be used to estimate free ion concentrations of introduced Al[3+], F[-], Na[+] in aquatic environments.  Free ion concentrations will be used to estimate toxicity.  A similar approach has been used to assess agricultural uses of inorganic copper salts (Ecological Risk Assessment for Cu Containing Pesticides, 4/20/06).  

(2) 		Terrestrial Exposure Models

The existing acute toxicity values for birds, mammals and invertebrates are all greater than the highest dose/concentration tested.  For those studies that have mortalities, the T-REX model will be used for a quantitative estimate of risk and a risk description will be conducted.  For those studies with no mortalities, only a risk description will be given.  The focus of terrestrial wildlife exposure estimates is for birds (also acting as surrogate for reptiles and terrestrial-phase amphibians) and mammals with an exposure route emphasis on uptake through the diet.  The cryolite residues in or on potential dietary sources for mammals and birds (e.g., vegetation, insects, and seeds) will be estimated using the Tier I model T-REX (Version 1.4.1, 2008).  In this Tier I assessment, it is assumed that organisms are exposed to one active ingredient in a given exposure scenario.  In all screening-level assessments, the organisms are assumed to consume 100% of their diet as one food type.  

The approach used to estimate exposure of terrestrial animals to cryolite will be based on potential foliar applications of cryolite.  Upper-bound exposure levels will be calculated for spray applications of cryolite using the maximum proposed application rates.  The exposure estimates are based on a database of pesticide residues on wildlife food sources associated with specified application rates (Hoerger and Kenaga, 1972; Fletcher et al., 1994).  Essentially, for a single application, there is a linear relationship between the amount of pesticide applied and the amount of pesticide residue present on a given food item.  Food item residue levels are then linearly adjusted based on application rate.  The upper-bound estimates are used to estimate risks since these values represent the high-end exposure that may be encountered for terrestrial species that consume food items that have received label-specified pesticide application.  Although these represent higher-end estimates, they do not represent the highest possible exposure estimates.  

T-REX is a simulation model that, in addition to incorporating the relationship between application rate and food item residue concentrations, accounts for pesticide degradation in the estimation of terrestrial EECs.  T-REX calculates pesticide residues on each type of food item on a daily interval for one year.  A first-order decay function is used to calculate the residue concentration at each day based on the concentrations present from both initial and all subsequent applications.  The decay rate is dependent on the foliar dissipation half-life.  The food item concentration on any given day is the sum of all concentrations up to that day, taking into account the first-order degradation.  The initial application occurs on day 0 (t=0) and the model runs for 365 days.  Over the 365-day run, the highest residue concentration is the measure of exposure (EEC) used to calculate risk quotients (RQs).

Foliar dissipation and residue decline studies can be important in estimating exposure because they essentially determine how long the pesticide remains in or on food items after application.  In many cases, neither empirically determined foliar dissipation nor residue decline half-life (with a day 0 residue) values are available, in which case the default value of 35 days is used (Willis and McDowell, 1987).  

EECs for terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant (version 1.2.2, 12/26/2006).  This model uses estimates of pesticides in runoff and in spray drift to calculate EECs.  EECs are based upon solubility, application rate and minimum incorporation depth.  

The AgDRIFT spray drift model (v2.01; May 2001) is used to assess exposures of organisms to cryolite deposited on terrestrial habitats by spray drift.
SIP (Screening Imbibition Program)

The Screening Imbibition Program (SIP v.1.0, Released June 15, 2010) may be used to calculate an upper bound estimate of exposure using cryolite's solubility (1200 mg/L), the most sensitive acute avian toxicity endpoint (LD50>2150 mg a.i./kg bw for bobwhite quail) and the most sensitive acute mammalian toxicity endpoint (LD50: 1500 mg a.i./kg bw for the rat).  Drinking water exposure alone was not determined to be a potential pathway of concern for avian/mammalian species on an acute basis.  Although drinking water exposure alone does not appear to be of concern, this does not take into account that when aggregated with other exposure pathways (i.e., dietary food sources, dermal, inhalation) drinking water may contribute to a total exposure that has a potential for effects on non-target animals.  Detailed information about SIP v.1.0, as well as the tool, can be found on the EPA's website at: http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial.

      Measures of Effects

Ecological effects data are used as measures of direct and indirect effects to biological receptors.  Data are typically obtained from registrant-submitted studies or from literature studies identified by ECOTOX.  The ECOTOX database provides more ecological effects data in an attempt to bridge existing data gaps.  ECOTOX is a source for locating single chemical toxicity data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and wildlife.  ECOTOX was created and is maintained by the USEPA, Office of Research and Development, and the National Health and Environmental Effects Research Laboratory's Mid-Continent Ecology Division.

The acute measures of effect used for animals in this assessment are the LD50, LC50 and EC50.  LD stands for "Lethal Dose", and LD50 is the amount of a material, given all at once, that is estimated to cause the death of 50% of the test organisms.  LC stands for "Lethal Concentration" and LC50 is the concentration of a chemical that is estimated to kill 50% of the test organisms.  EC stands for "Effective Concentration" and the EC50 is the concentration of a chemical that is estimated to produce a specific effect in 50% of the test organisms.  Endpoints for chronic measures of exposure for listed and non-listed animals are the NOAEL/NOAEC and NOEC.  NOAEL stands for "No Observed-Adverse-Effect-Level" and refers to the highest tested dose of a substance that has been reported to have no harmful (adverse) effects on test organisms.  The NOAEC (i.e., "No-Observed-Adverse-Effect-Concentration") is the highest test concentration at which none of the observed effects were statistically different from the control.  The NOEC is the No-Observed-Effects-Concentration.  For non-listed plants, only acute exposures are assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for listed plants either the NOAEC or EC05 is used.

Information on the potential effects of cryolite on non-target animals is also collected from the Ecological Incident Information System (EIIS).  The EIIS is a database containing adverse effect (typically mortality) reports on non-target organisms where such effects have been associated with the use of pesticides.  Information on incidents involving avian species is also provided through the Avian Monitoring Information System (AIMS), which is maintained by the American Bird Conservancy.  

Where available, sub-lethal effects observed in both registrant-submitted and open literature studies will be evaluated qualitatively.  Such effects may include behavioral changes (e.g., lethargy and changes in coloration).  Quantitative assessments of risks, though, are limited to those endpoints that can be directly linked to the Agency's assessment endpoints of impaired survival, growth and reproduction.

The assessment of risk for direct effects to non-target organisms makes the assumption that the toxicity of cryolite to birds is similar to terrestrial-phase amphibians and reptiles.  The same assumption is made for fish and aquatic-phase amphibians.

      Integration of Exposure and Effects

Risk characterization is the integration of exposure and ecological effects characterization to determine the potential ecological risk from the use of pesticides and the likelihood of direct and indirect effects to non-target organisms in aquatic and terrestrial habitats.  The exposure and toxicity effects data are integrated in order to evaluate the risks of adverse ecological effects on non-target species.  For the assessment of risks, the RQ method is used to compare exposure and measured toxicity values.  EECs are divided by acute and chronic toxicity values.  The resulting RQs are then compared to the Agency's Levels of Concern (LOCs) (USEPA 2004).  These criteria will be used to indicate when cryolite's uses, as directed on the label, have the potential to cause adverse direct or indirect effects to non-target organisms.  In addition, incident data from the EIIS will be considered as part of the risk characterization.

      B.	Endangered Species

Consistent with the Agency's responsibility under the Endangered Species Act (ESA), EPA will evaluate risks to Federally-listed threatened and/or endangered (listed) species from registered uses of cryolite.  This assessment will be conducted in accordance with the Overview Document (USEPA, 2004), provisions of the ESA, and the Services' Endangered Species Consultation Handbook (USFWS/NMFS, 1998). 

The assessment of effects associated with registrations of cryolite is based on an action area.  The action area is considered to be the area directly or indirectly affected by the federal action, as indicated by the exceedance of Agency Levels of Concern (LOCs) used to evaluate direct or indirect effects.  The Agency's approach to defining the action area under the provisions of the Overview Document (USEPA, 2004) considers the results of the risk assessment process to establish boundaries for that action area with the understanding that exposures below the Agency's defined LOCs constitute a no-effect threshold.  For the purposes of this assessment, attention will be focused on the footprint of the action (i.e., the area where cryolite application occurs), plus all areas where offsite transport (i.e., spray drift and runoff) may result in potential exposure that exceeds the Agency's LOCs.  Specific measures of ecological effect that define the action area for listed species include any direct and indirect effects and/or potential modification of its critical habitat, including reduction in survival, growth, and reproduction as well as the full suite of sub-lethal effects available in the effects literature.  Therefore, the action area extends to a point where environmental exposures are below any measured lethal or sub-lethal effect threshold for any biological entity at the whole organism, organ, tissue, and cellular level of organization.  In situations where it is not possible to determine the threshold for an observed effect, the action area is not spatially limited and is assumed to be the entire United States. 
      B. Drinking Water Assessment
            
The drinking water assessment to be conducted for cryolite must account for the fact that it dissociates to form Al[3+], F[-], and Na[+].  Tier II Pesticide Root Zone Model- Exposure Analysis Modeling System (PRZM/EXAMS  can be used to estimate the concentration of introduced Al[3+], F[-], and Na[+] in surface water.  Chemical equilibria modeling will be used to estimate free ion concentrations of introduced Al[3+], F[-], Na[+] in surface source drinking water.

      D.	Clean Water Act

Cryolite is not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act based on information provided at: http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T#tmdl_by_pollutant.  In addition, no Total Maximum Daily Loads (TMDL) have been developed for cryolite.

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 OtherWater Quality Data in OPP's Registration Review Risk Assessment and Management Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf), in order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments.

      E.	Anticipated Data Needs

      Environmental Fate

There are no fate data requirements at this time.

      Environmental Effects

Guideline Number: 850.1075 
Study Title:  Fish Acute Toxicity Test, Estuarine/Marine
                       Rationale for Requiring the Data
Acute toxicity data are not available for estuarine and marine fish.  According to 40 CFR Part 158, Subpart G (Ecological Effects) §158.630 (Terrestrial and Aquatic Nontarget Organism Data Requirements Table), the acute marine/estuarine fish study is required for all terrestrial use patterns except greenhouse and indoor uses.  Cryolite has several outdoor agricultural and ornamental uses. Additionally, although there should be no difference in the accumulation of aluminum or fluorine moieties in animals under most agricultural conditions, cryolite applications in aquatic environments may contribute to Al[3+] toxicity in aquatic organisms.  Therefore, effects on non-target estuarine/marine fish cannot be discounted, and the level of risk is unknown.   
                         Practical Utility of the Data
How will the data be used?
Estuarine/marine fish acute toxicity data will be used to determine the potential for cryolite to affect fish species in estuarine/marine environments.  The data will reduce uncertainties associated with the current risk assessment for estuarine/marine fish and will improve the Agency's understanding of the potential effects of cryolite on aquatic animals.  In the absence of data specific for these fish, data from freshwater fish species will be used as a surrogate for estuarine/marine fish.

How could the data impact the Agency's future decision-making?
Using toxicity data from a freshwater species as a surrogate for estuarine/marine species increases the uncertainty for assessing risks to estuarine/marine species in screening-level assessments.  Additionally, if future endangered species risk assessments are performed without these data, the Agency would have to presume risk to listed estuarine/marine fish species in the absence of such data for cryolite.  Therefore, the use of cryolite may need to be restricted in areas where listed species could be exposed.  The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for cryolite that are unnecessarily severe.

Guideline Number:  850.1025
Study Title:  Oyster Acute Toxicity Test (Shell Deposition)
                       Rationale for Requiring the Data
Acute toxicity data are not available for estuarine/marine mollusk.  According to 40 CFR Part 158, Subpart G (Ecological Effects) §158.630 (Terrestrial and Aquatic Nontarget Organism Data Requirements Table), the oyster acute toxicity test is required for all terrestrial use patterns except greenhouse and indoor uses.  Cryolite has several outdoor agricultural and ornamental uses. Additionally, although there should be no difference in the accumulation of aluminum or fluorine moieties in animals under most agricultural conditions, cryolite applications in aquatic environments may contribute to Al[3+] toxicity in aquatic organisms.  Therefore, effects on non-target estuarine/marine mollusks cannot be discounted, and the level of risk is unknown.   
                         Practical Utility of the Data
How will the data be used?
Estuarine/marine mollusk acute toxicity data will be used to determine the potential for cryolite to affect mollusk species in estuarine/marine environments.  The data will reduce uncertainties associated with the current risk assessment for estuarine/marine invertebrates and will improve the Agency's understanding of the potential effects of cryolite on aquatic animals.  

How could the data impact the Agency's future decision-making?
If future endangered species risk assessments are performed without these data, the Agency would have to presume risk to listed estuarine/marine mollusk species in the absence of such data for cryolite.  Therefore, the use of cryolite may need to be restricted in areas where listed species could be exposed.  The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for cryolite that are unnecessarily severe.

Guideline Number: 850.4400 
Aquatic Plant Growth Tier I Study (Vascular Aquatic Plant) 
                       Rationale for Requiring the Data
Aquatic (both vascular and non-vascular species) toxicity studies and associated risk analysis of plants are required for registration of pesticides with outdoor uses (CFR Part 158).  There are currently no data available to determine the levels of cryolite that could result in effects to aquatic vascular plants.  Additionally, although there should be no difference in the accumulation of aluminum or fluorine moieties in plants or animals under most agricultural conditions, cryolite applications in acidic soils or aquatic environments may contribute to Al[3+] toxicity in plants and aquatic organisms.  Therefore, effects on non-target aquatic plants cannot be discounted, and the level of risk is unknown.  Therefore, an aquatic vascular plant study is required as specified in 40 CFR Part 158 (OPPTS Guideline 850.4400).
                         Practical Utility of the Data
How will the data be used?  
Data from Tier I aquatic plant toxicity studies will be used to estimate potential risks to aquatic plants from cryolite exposure.  The data will reduce uncertainties associated with the current risk assessment for plants and will improve our understanding of the potential effects of cryolite use on aquatic plants.  Because plants form the basis of most habitats and significantly contribute to overall environmental quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental management.  The data will also be used in determining whether a "may affect" to Federally-listed threatened and endangered species is likely under the Endangered Species Act.

Additionally, the need for labeling language to mitigate effects on non-target aquatic plant species is unknown.  Results of this study would be used to determine if surface water exposure concentrations, due to run-off, are below levels of concern at the current label rates and to identify what, if any, label language is needed to mitigate identified risks.

How could the data impact the Agency's future decision-making?
Without aquatic plant growth data for cryolite, the Agency cannot determine the levels of cryolite that result in effects to vascular aquatic plants.  Until these data are available, the registration decision will be based on the information listed on the label.  The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act, and could result in use restrictions for cryolite which may otherwise be avoided, or which are unnecessarily severe.

Guideline Number: 850.5400 
Aquatic Plant Growth Tier I Study (Non-vascular Aquatic Plant) 
                       Rationale for Requiring the Data
Aquatic (both vascular and non-vascular species) toxicity studies and associated risk analysis of plants are required for registration of pesticides with outdoor uses (CFR Part 158).  There are currently no data available to determine the levels of cryolite that could result in effects to aquatic non-vascular plants. Additionally, although there should be no difference in the accumulation of aluminum or fluorine moieties in plants or animals under most agricultural conditions, cryolite applications in acidic soils or aquatic environments may contribute to Al[3+] toxicity in plants and aquatic organisms.   Therefore, effects on non-target aquatic plants cannot be discounted, and the level of risk is unknown. Therefore, aquatic non-vascular plant studies are required as specified in 40 CFR Part 158 (OPPTS Guideline 850.5400).
                         Practical Utility of the Data
How will the data be used?  
Data from Tier I aquatic plant toxicity studies will be used to estimate potential risks to aquatic plants from cryolite exposure.  The data will reduce uncertainties associated with the current risk assessment for plants and will improve our understanding of the potential effects of cryolite use on aquatic plants.  Because plants form the basis of most habitats and significantly contribute to overall environmental quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental management.  The data will also be used in determining whether a "may affect" to Federally-listed threatened and endangered species is likely under the Endangered Species Act.

Additionally, the need for labeling language to mitigate effects on non-target aquatic plant species is unknown.  Results of this study would be used to determine if surface water exposure concentrations, due to run-off, are below levels of concern at the current label rates and to identify what, if any, label language is needed to mitigate identified risks.

How could the data impact the Agency's future decision-making?
Without aquatic plant growth data for cryolite, the Agency cannot determine the levels of cryolite that result in effects to non-vascular aquatic plants.  Until these data are available, the registration decision will be based on the information listed on the label.  The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act, and could result in use restrictions for cryolite which may otherwise be avoided, or which are unnecessarily severe.

Guideline Numbers:  850.4100 and 850.4150
Study Title:  Terrestrial Plant Toxicity Tests (Tier I)
                       Rationale for Requiring the Data
Terrestrial plant toxicity studies and associated risk analysis of plants are required for registration of pesticides with outdoor uses (CFR Part 158).  For terrestrial plants, Tier II studies are required when potential concerns are triggered (i.e., when there is some indication that there may be significant toxicity to plants).  These indicators may be an herbicidal mode of action or statements on the label indicating toxicity to plants.  None of these indicators are present for cryolite.  Because of the wide number of currently registered agricultural uses for cryolite, there is a potential for endangered and/or threatened species to be in the vicinity of use sites.  Additionally, although there should be no difference in the accumulation of aluminum or fluorine moieties in plants or animals under most agricultural conditions, cryolite applications in acidic soils may contribute to Al[3+] toxicity in plants.  Tier I seedling emergence and vegetative vigor studies (OPPTS Guidelines 850.4100 and 850.4150) are, therefore, required.  
                         Practical Utility of the Data
How will the data be used?
Tier I vegetative vigor and seedling emergence data for terrestrial plants will be used to determine the potential for cryolite to affect non-target plant species in the terrestrial environment.  In the absence of data specific for these plants, risk to terrestrial plants will be assumed.

How could the data impact the Agency's future decision-making?
If future endangered species risk assessments are performed without these data, the Agency would have to presume risk to non-target terrestrial plants from use of cryolite. Therefore, use of cryolite and its formulated products may need to be restricted in areas where listed species could be exposed.  The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for cryolite that are unnecessarily severe.

      Other Information Needs

   There are no other information needs at this time.  

The analysis plan will be revisited and may be revised depending upon the data available in the open literature and the information submitted by the public in response to the opening of the Registration Review docket.

VIII. References

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger.  1994.  Literature review and evaluation of the EPA food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on plants.  Environ. Tox. Chem. 13:1383-1391.

Hoerger, F., and E.E. Kenaga.  1972.  Pesticide residues on plants: Correlation of representative data as a basis for estimation of their magnitude in the environment.  In F. Coulston and F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and Technology, Georg ThiemePubl, Stuttgart, West Germany, pp. 9-28.  Support Document #14.  

U.S. Environmental Protection Agency (USEPA), 2004.  Overview of the Ecological Risk
Assessment Process in the Office of Pesticide Programs.  Office of Prevention, Pesticides, and Toxic Substances.  Office of Pesticide Programs.  Washington, D.C.  January 23, 2004

U.S. Environmental Protection Agency (USEPA), 1996.  Reregistration Eligibility Decision for Cryolite.  Office of Prevention, Pesticides and Toxic Substances.  Office of Pesticide Programs.  Washington, D.C. August, 1996.

USEPA. 2006. User's Guide: TerrPlant Version 1.2.2.  United States Environmental Protection Agency. Environmental Fate and Effects Division.

USEPA. 2008. User's Guide: T-REX Version 1.4.1 (Terrestrial Residue Exposure model).  United States Environmental Protection Agency. Environmental Fate and Effects Division.

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS),  1998.  Endangered Species Consultation Handbook:  Procedures for Conducting Consultation and Conference Activities Under Section 7 of the Endangered Species Act.  Final Draft.  March 1998

Willis, G. H. and L..L. McDowell, 1987.  Pesticide Persistence on Foliage. in Reviews of Environmental Contamination and Toxicology.  100:23-73.