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### UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHI NGTON D.C., 20460

MEMORANDUM May 4 , 2011 Subject: Registration Review

– Preliminary Problem Formulation for Ecological Risk and Environmental Fate, Endangered Species, and Drinking Water Asse ssments for Fipronil ( PC Code 1 29121 ; DP 387319 ) To: Susan Bartow , Chemical Review Manager

Eric Olson , Team Leader Risk Management and Implementation Branch IV Pesticide Re
- evaluation Division (PRD) Office of Pesticide Programs From: Edward Odenkirchen , Ph.D., Senior Biologist

Stephen Wente, Ph.D., Biologist Environmental Risk Branch 1 Environmental Fate and Effects Division (EFED) Office of Pesticide Programs Through: Nancy

Andrews , Ph.D., Chief Sujatha Sankula, Ph.D., Risk Assessment Process L eader Environmental Risk Branch 1 Environmental Fate and Effects Division (EFED) 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, fipronil (PC 129121). The problem formulation draws on information from both open literature and studies submitted by the technical registrants in response to data requirements. This document is intended to provide an overview of what is currentl y known regarding the environmental fate and ecological effects associated with fipronil and all of its degradates and outlines uncertainties regarding attributes of the parent compound and its transformation products. It describes the preliminary

ecological risk hy

pothesis and the processes that will be used during the completion of drinking water and ecological risk assessments in supp ort of registration review. This document also recommends studies that should be included in a data call
- in (DCI) to address uncertainties surrounding the environmental fate and potential ecological effects of fipronil.

### Page 2 of 71 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

# Problem Formulation for the Environmental Fate and Ecological Risk,

Endangered Species, and Drinking Water Assessment s in Support of the Registration Review of Fipronil

N N Cl

Cl H 2 

# N S

C CF 3 

# O CF 3



# N Fipronil (CAS # 120068 - 37 - 3 ) 

### Prepared by: Edward Odenkirchen, Ph.D., Senior Biologist Stephen Wente, Ph.D., Biologist U. S. Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division Environmental Risk Branch I 1200 Pennsylvania Ave., NW Mai l Code 7507P Washington, DC 20460 Reviewed by: Anita Ullagaddi , Biologist Faruque Khan , Ph.D., Senior Scientist

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### Table of Contents I. Purpose ................................ ................................ ................................ ........................... 5 II. Problem Formulation ................................ ................................ ................................ ..... 5 A. Nature of Regulatory

Action ................................ ................................ ..................... 5 B. Conclusions from Previous Risk Assessments ................................ .......................... 6 1. Fipronil Ecological Risk Assessments ................................ ................................ ... 6 2. Drinking W

ater Exposure Assessments ................................ ................................ . 7 III. Stressor Source and Distribution ................................ ................................ ................. 8 A. Mechanism of Action ................................ ................................ ................................ 8 B. Overview of Pesticide Usage ................................ ................................ .................... 8 C. Environmental Fate and Transport ................................ ................................ .......... 12 IV . Receptors ................................ ................................ ................................ ................... 18 A. Effects to Aquatic Organisms ................................ ................................ ................. 19 B. Effects to Terrestrial Organisms ................................ ................................ ............. 20 C. Degradate toxicity ................................ ................................ ................................ ... 21 D. Ecological Incidents ................................ ................................ ................................ 21 D. Ecos ys tems Potentially at Risk ................................ ................................ ............... 22 V. Assessment Endpoints ................................ ................................ ................................ . 22 VI . Conceptual Model ................................ ................................ ................................ ....... 22 A. Risk Hy

pothesis ................................ ................................ ................................ ...... 23 B. Conceptual Diagram ................................ ................................ ................................ 23 VII. Anal ys is Plan ................................ ................................ ................................ ............ 25 A. Stressors of Concern ................................ ................................ ............................... 26 B. Measures o f Exposure ................................ ................................ ............................. 26 C. Measures of Effect ................................ ................................ ................................ .. 28 D. Integration of Exposure and Effects ................................ ................................ ........ 29 1. Deterministic and Probabilistic Assessment Methods ................................ ......... 30 E. Endangered Species Assessments ................................ ................................ ........... 30 F. Drinking Water Assessment ................................ ................................ .................... 31 G. Preliminary

I dentification of Data Gaps ................................ ................................ . 31 H. Preliminary

I dentification of Data Gaps ................................ ................................ . 32 1. Fate ................................ ................................ ................................ ...................... 32 2. Effects ................................ ................................ ................................ ................... 35 VIII. References ................................ ................................ ................................ ............... 40 Appendix 1. Currently

Registered Uses of Fipronil. ................................ ....................... 43 Appendix 2. Chemical Names, Structures, Maximum Reported Amounts of Fipronil and its Degradates and Ov erview of Degradation Pathway s. ................................ .................. 51 Appendix 3. Available Effects data from most recent ecological risk assessment in 2007

................................ ................................ ................................ ................................ ........... 57 List of Tables Table 1. History

of U.S. Environmental Protection Agency ecological risk assessments for fipronil. ................................ ................................ ................................ .......................... 6 Table 2. General phys ico
- chemical and environment al fate properties of fipronil and

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### degradates of concern. ................................ ................................ ................................ ...... 13 Table 3. Test Species Evaluated for Assessing Potential Ecological Effects of Fipronil and the Associated Acute Toxicity Classific ation. ................................ ........................... 19 Table 4. Available environmental fate data for fipronil and remaining data gaps. ......... 32 Table 5. Available environmental fate data for fipronil sulfide (MB 54950) and remaining data gaps. ................................ ................................ ................................ ......... 33 Table 6. Available environmental fate data for fipronil sulfone (MB 46136) and remaining data gaps. ................................ ................................ ................................ ......... 34 Table 7. Available environmental fate data for MB46513 and remaining data gaps. ..... 34 Table 8. Non
- Target Organism Toxicity Data Gaps ................................ ........................ 35 Table 9. Terrestrial Organism Toxicity Endpoints Used in Past Risk Assessment ......... 38 Table 10. Aquatic Organism Toxicity Endpoints Used in Past Risk Assessment ........... 38 List of Figures Figure 1. Corn Production Areas in the United States ................................ ..................... 10 Figure 2. General Fire Ant Quarantine Area in the United States (updated and more detailed 2009 map available at: http://www.aphis.usda.gov/plant_health/plant_pest_info/fireants/downloads/fireant.pdf).

................................ ................................ ................................ ................................ ........... 10 Figure 3. Sweet Potato Production Areas in the United States ................................ ........ 11 Figure 4. Potato Production Areas in the United States ................................ ................... 11 Figure 5. Conceptual model depicting stressors, exposure pathways, and potential effects to aquatic organisms from the use of fipronil. Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk. ................................ ........... 24 Figure 6. Conceptual model depicting stressors, generic exposure pathways, and potential effects to terrestrial organisms (terrestrial plants, terrestrial invertebrates, and dietary routes of exposure for terrestrial vertebrates) from the use of fipronil. Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk.

................................ ................................ ................................ ................................ ........... 25

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# I. Purpose The purpose of this problem formulation is to provide an understanding of the environmental fate and ecological effects of the registered uses of fipronil, also known as MB 46030. Fipronil is a non
- sy stemic , chiral phenylpy razole insecticide . The chiral center is associated with the sulfur in parent fipronil. The current registrations are onl y for the racemic mixture of stereoisomers (50% R: 50% S). It is formulated as a technical chemical, formulation intermediate, dust, granular, pelletted/tabletted, wettable powder, impregnated materials, emulsifia ble concentrate, flowable concentrate, soluble concentrate, solution
- ready to use, or pressurized liquid , depending on the use. Current outdoor fipronil uses include broadcast treatment for control of fire ants, carpenter ants, and nuisance ants; in
- furrow treatment for control of corn root worm on corn and wire worms on sweet potatoes/potatoes; seed treatments for corn; soil injection for control of termites; and bait treatments for fire ants, fruit flies, and Texas leaf
- cutter ants. This document will pro vide a plan for analyzing data relevant to fipronil and for conducting environmental fate and ecological risk, endangered species and drinking water assessments for its registered uses. Additionally , this problem formulation is intended to identify data g aps, uncertainties, and potential assumptions used to address those uncertainties, relative to characterizing the ecological risk associated with the registered uses of fipronil. 

# II. Problem Formulation A. Nature of Regulatory Action The Food Quality Protection Act of 1996 mandated EPA to implement a new program for assessing the risks of pesticides, i.e ., registration review (http://www.epa.gov/oppsrrd1/registration_review/). All pestic ides distributed or sold in the United States generally must be registered b y 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, w orkers, 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 pe sticides to ensure that as change occurs, products in the marketplace can be used safel y. 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 fipronil continues to meet the FIFRA standard for registration. This problem formulation for the environmental fate

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### and ecological risk aTable 1 Table 1 essment chapter in support of the registration review is intended for the initial docket opening the public phase of the review process. 

## B. Conclusions from Previous Risk Assessments Fipronil was first registered in 19 93 . The Agency conducted multiple subsequent ecological risk and drinking water assessments on f ipronil between 1993 and present . 1
. Fipronil Ecological Risk Assessments Because of the large number of fipronil ecological risk assessments and revisions to those assessments, the eco logical risk assessments are very briefl y summarized in Table 1 . Fipronil was not subject to the reregistration process due to its recent initial registration occurring after the November 1 st 

### , 1984 initial registration cut
- off dat e for chemicals required to undergo reregistration. However, a comprehensive risk assessment was performed (dated April 26, 1996) that is similar to the science chapters produced b y EFED in support of Reregistration Eligibility Decisions (RED). Table 1 . History of U.S. Environm ental Protection Agency ecological risk assessments for fipronil. Date Title Risk Concerns 1/16/96 Request for a Section 3 of FIFRA for use of Fipronil

(GAUNTLET 0.1G) on golf and commercial turfgrass (not fo r use on domestic turf or sod farms ) ( D214746 ) Risks to estuarine/marine invertebrates 4/26/96 Fipronil: Environmental Assessment, Current for the Turf

Registration (No DP Barcode) Possible risks to estuarine/marine invertebrates 7/12/96 Request for a Se ction 3 of F IFRA f or use of Fipronil (REGENT 1.5G) on corn (D214762) Risk to freshwater and estuarine invertebrate specie s 8/21/96 Request for Section 3 of FI FRA for use of Fipronil (Termidor 80

WG) as a termiticide f

o r preconstruction, post - construction, hollow block foundations, soil excavation, and post poles and wood landscape ornamentation. ( D227607 ) None No date EFED's Section 3 Registration Eligibility Decision Chapter' for

Fipronil Use on Corn ( D236430, D236432, D237516, D2285 55, D237727, D236394, D2375 16, D2375 17, D236956, D23971 ) Risk for direct chronic effects to both fr e sh and salt water fish species 11/20/97 EFED's Section 3 Registration Eligibility Decision Chapter for

Fipronil Use on Corn Ac ute and chronic estuarine invertebrate risks 4/16 /99 EFED's Section 3 Registra on Eligibility Decision Chapter for

Fipronil Use Rice as a Pre
- Plant Broadcast Treatment (No DP Barcode) Risks for estuarine organisms 7/6/99 EFED's Section 3 Registration Review for Fipronil Use in

Potting Soil for Fire Ant Control and Other Insect Pests (D254052) None 7/19/99 Fipronil: Emergenc y Exemption Use on Rangeland in Wyoming:

Environmental Risk Assessment Conclusions ( D253226 ) None 8/19/99 EFED's Section 3 Registrati on Eligibility Decision Chapter for

Fipronil Use as Granular and Bait applications for control of Fire Ants and Other Turf pests ( D253952, D254316, D25407 5 , D253660 ) Ac ute and chronic estuarine invertebrate and fish risks

### Page 7 of 71 Date Title Risk Concerns 12/6/99 EFED's Section 3 Registrati on Eligibility Decision Chapter for

Fipronil Us e as Granular and Bait application s for control of Fire Ants and Other Turf pests (Revised) ( D260843, D253952, D2543 16 , D254075, D253660, D24406 1 ) Risks to estuarine/marine invertebrates
4/10/01 EFED's Section 3 Registration Eligibility Decision Chapter f or Fipronil Use as Granular Applications for Control of Fire Ants and Other Turf Pests (Addendum) ( D260607, D273236, D273241, D273375, D274014 ) Acute and chronic risks to freshwater and estuarine/marine invertebrates 6/20/01 Section 3 Registration Eligib i lity Decision Chapter for Fipronil Use on Cotton ( D236414 ) Ac ute and chronic estuarine invertebrate and fish risks 11/15/01 Updated Environmental Risk Assessment for Fipronil. Corn: in
furrow application and seed treatment (D277292, D27729 1, D277289, D278 506, D269236 ) Acute and chronic risks to freshwater and estuarine/marine invertebrates 12/5/01 Updated Environmental Risk Assessment for Fipronil. Corn: in
furrow application and seed treatment ( D277292, D277291, D277289, D278506, D269236 ) C hronic freshwater aquatic invertebrate 4/18/02 Section 3 Registration Request for Uses of Firponil in Maxforce

Tic k Management System Bait Station Treatment of Small Mammals ( D281 019) None 1/26/05 Special Local Needs Registration [Section 24(c)] for Fipronil

(Topchoi ce ® ) Use to Control Fire Ants in Arizona (D311943) Acute endangered freshwater aquatic invertebrates
8/31/05 Section 18 Ecological Risk Assessment for F ipronil Use to

Control Cabbage Maggot in Turnip and Rutabaga ( D356402 ) Acute lethal and reproduction ri sks to birds ; reproductive effects in insectivorous mammals ; acute and chronic effects to freshwater invertebrates 2/6/07 Ecological Risk Assessment for Fipronil Uses (D 331595,

331519, 331593, 329522, 314530, 332424, 325983, 326009, 326000, 325999, 325997 , 325990, 326003, 331867, 314530, 322414, 314197, 331714, 331713, 313295, 331872, 335805 ) Acute and chronic risks to freshwater and estuarine/marine invertebrates
3/30/07 Ecological Risk Assessment for Fipronil Uses (Addendum)

(D 331595, 331519, 331593, 32 9522, 314530, 332424, 325983, 326009, 326000, 325999, 325997, 325990, 326003, 331867, 314530, 322414, 314197, 331714, 331713, 313295, 331872, 335805 ) Acute and chronic terrestrial vertebrate risk based on revise assessment for onion
- seed treatment 4/18/07 Updated Section 18 Ecological Risk Assessment for Fipronil

Use to Control Cabbage Maggot in Turnip and Rutabaga ( D33 8854 ) Acute and chronic effects to freshwater invertebrates 5/15/07 Section 18 Ecological Risk Assessment for Fipronil Use to

Control Cabb age Maggot in Turnip and Rutabaga. Add endum regarding assessment of potential for effects to listed fishes ( D338854 ) Indirect effects to endangered fish species due to acute and chronic risk to fr eshwater invertebrates 

### 2. Drinking W

ater Exposure Assess ment s A drinking water exposure assessment was conducted in 2006 in support of human health risk assessment (DP Barcode 322415 ) , which was subsequently revised in 2007 (under the same DP Barcode 322415) for the parent fipronil and the individual degradati on products , MB 46513, MB 461 36 and MB45950 . PRZM (3.12 beta) and EXAM (2.97.5) using PE4V0l.pl (August 13, 2003) were used to estimate fipronil residue concentrations in drinking water. From the registered and proposed uses for fipronil, the highest

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### concentrations of fipronil and its degradation products in surface source drinking water were expected to be from the proposed use on onion seeds. Fipronil concentrations in surface source water are not expected to exceed 2,654.1 ng/L for the 1 in 10 year peak concentration, 317.9 ng/L for 1 in 10 year annual average concentration, and 161.2 ng/L for the 30 ye ar annual average concentration . However, the onion seed treatment was not approved. Therefore, the drinking water exposure may need to be re
- assessed. Ground water concentrations for fipronil and its degradation products were estimated using SC2.3 (July

29, 2003). The proposed use on in
- furrow corn and rutabagas/turnip uses had the highest predicted concentration (21 ng/L) in ground water. 

# III. Stressor Source and Distribution Fipronil is a broad
- spectrum phenylpy razole insecticide. The current and proposed new uses for fipronil are in
- furrow treatments, broadcast treatments, seed treatments, and bait stations for control of insect pests. The use pattern includes residential uses for control of termites, fire ants, carpenter/nuisance ants, leaf cutter ants, and fruit flies on the following crops: corn, corn seed, sweet potato, potato, and pine seedlings. Fipronil use for control of fire ant is limited to the USDA 14 state plus Puerto Rico fire ant quarantine area. Distributions of the crops were determined based on 1997 AgCensus data and 70 Code of Federal Regulation, 1996 . Maps showing these distributions are included in Section B (below). Because fiproni l degradation products are persistent in soil (soil degradation t 1/2 

### ~ 700 day), they

are expected to accumulate in soil from successive use of fipronil (MRID 46477001). The persistence of fipronil degradation products is expected to prolong ecological exp osure. 

## A. Mechanism of Action Fipronil affects the gamma
- aminobuty ric acid neurotransmission sy stem by interfering with the passage of chloride. In addition, research data indicate that fipronil displays a higher potency

in the insect GABA chloride ch annel than in the vertebrate GABA chloride channel, which may indicate selective toxicity (Hainzl and Casida, 1996). Additionally , there are open
- literature data showing enantioselective biodegradation of fipronil in rainbow trout (Konwick et al, 2006). 

## B . Overview of Pesticide Usage Current labels allow outdoor use of fipronil on forestry uses (forest tree management/forest pest management, forest trees (softwoods, conifers), and pine (forest/shelterbelt)); outdoor residential uses (household/domestic dwellings outdoor premises, refuse/solid waste containers (garbage cans), and residential lawns); terrestrial food + feed crop uses (orchards (unspecified), potato and white/Irish); terrestrial non -

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### food + outdoor residential uses (fencerows/hedgerows, ornam ental and/or shade trees, and paths/patios); and terrestrial non - food crop uses (Christmas tree plantations, commercial storages/warehouses premises, commercial/industrial lawns, commercial/institutional/industrial premises/equipment (outdoor), field corn, golf course turf, industrial / construction areas (outdoor), nonagricultural outdoor buildings/structures, nonagricultural uncultivated areas/soils, nursery stock, ornamental and/or shade trees, ornamental herbaceous plants, ornamental lawns and turf, ornamental non - flowering plants, ornamental sod farm (turf), ornamental woody shrubs and vines, paved areas (private roads/sidewalks), potting soil/topsoil, recreation area lawns, recreational areas, refuse/solid waste sites (outdoor), utility poles / right
- o f

- way , wood protection treatment to buildings/products outdoor, and zoos . In door use of fipronil include indoor food uses (dairy farm milk handling facilities/equipment, food/grocery

/marketing/storage/distribution facility premise, and household/domestic dwellings indoor food handling areas); indoor medical uses (hospitals/medical institutions premises (human/veterinary)); indoor non - food uses (bathroom premises/hard surfaces, commercial storages/warehouses premises, commercial transportation facilities
- non feed/nonfood, commercial/institutional/industrial premises/equip. (indoor) , dairies/cheese processing plant premises (nonfood contact) , eating establishments , eating establishments food handling areas (nonfood contact) , eating establishments food serving areas (nonfood contact) , eating establishments non
food areas (nonfood contact) , feed mills/feed processing plants , food processing plant non - food handling areas , food processing plant premises (nonfood contact) , food stores/markets/supermarkets premises , m eat processing plant premises (nonfood contact) , refuse/solid waste sites (indoor) , ships and boats, and zoos); and indoor residential uses (cats (adults/kittens), dogs/canines (adults/puppies), household/domestic dwellings contents, household/domestic dwe llings indoor premises, and refuse/solid waste containers (garbage cans). Currently registered uses of fipronil (with maximum application rates, maximum number of applications, and minimum re
- treatment intervals) are listed in Appendix 1 . A spatial anal ys is of the fipronil use areas in the United States suggests the predominant fipronil use areas are the Midwestern and Southeastern United States (Figures 1 and 2). These use areas are associated with conditional re gistrations for in
- furrow use of fipronil corn and broadcast/bait fipronil use for fire ant use in residential areas.

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Figure 1 . Corn Production Areas in the United States

Figure 2 . General Fire Ant Quarantine Area in the United States (updated and more detailed 2009 map available at: http://www.aphis.usda.gov/plant_health/plant_pest_info/fireants/downloads/fireant.pdf ). 

### Proposed uses of fipronil on sweet potato are not expected to extend the use area beyond the fire ant quarantine use areas (Figure 3). However, the use of fipronil on potatoes is expected to extend the fipronil use area into the Northeastern United States (Maine).

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Figure 3 . Sweet Potato Production Areas in the United States

Figure 4 . Potato Production Areas in the United States 

### The proposed pine seedling use for fipronil is expected to be in pine nursery areas for plantations associated with pulp and paper mill production ( i.e. , Southeastern United States) . Although the AMULETTM C - L label for fruit fly bait does not restrict the geographical use, the use area is expected to be limited to Hawaii (Personal Communication from Jack Arthur, BASF, 10/5/06). The proposed perimeter house treatment use of fipronil (TERMIDOR® SC, EPA Reg. No. 7969
- 210) will be predominantly

associated with urban and suburban areas. The geographic range of house perimeter use is expected to be correlated with geographic extent of termites. The screening
- level use assessment (SLUA) e stimates of agricultural uses of fipronil indicate that use on : corn (~100,000 lbs. a.i./year on average) account s for < 2.5 % of the total pesticide use on corn on average (maximum of ~5 %); potatoes (~2,000 lbs. a.i./year on average) accounts for < 2.5% o f the total use pesticide use on potatoes on average (maximum of < 2.5 %); sweet corn < 500 lbs. a.i./year on average) accounts for < 1% of the total use pesticide use on sweet corn on average (maximum of < 2.5 %) (USEPA

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### 20 10 ) (Values are calculated by merging pesticide usage data sources together; averaging across all observations, then rounding. ) 

## C. Environmental Fate and Transport Fipronil dissipation appears to be dependent on photodegradation in water, microbially mediated degradation, and soil binding. Data indicate that fipronil is relatively persistent and immobile in terrestrial environments. In aquatic environments, a determination of the environmental behavior of fipronil is more tentative because soil and aquatic metabolism studies provide contradictory data on fipronil persistence to microbiall y- mediated degradation processes. Photoly sis is expected to be a major factor in controlling fipronil dissipation in aquatic environments. Fipronil degrades to form persistent and immobile degradates (f

ipronil s ulfide (MB 45950) , f ipronil s ulfone (MB 46136) , and MB 46513 ) . These degradates are considered in the HED dietary tolerance expression for fipronil. Because fipronil and its degradates have a moderate to high sorption affinity to organic carbon, it is likely

sorption on soil organic matter will limit fipronil residue movement into ground and surface waters. However, fipronil residue may have the potential to move in very vulnerable soils ( e.g. , coarse - textured soils with low organic matter content) and in erodable soils when bound to particles entrained in runoff. In
- furrow fipronil applications are expected to limit runoff potential. Registrant
- submitted data defining the physical, chemical, fate and transport characteristics associated with fipronil and combined residues of concern are summarized in Table 2 . (Structural representations of fipronil and degradates may be found in Appendix 2.)

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Table 2 . General physico - chemical and envi ronmental fate properties of fipronil and degradates of concern . Fipronil Fipronil S ulfide (MB 45950) Fipronil S ulfone (MB 46136) MB 46513 Param eter Value(s) Source (M RID) Value(s) Source (M RID) Value(s) Source (M RID) Value(s) Source (M RID) Physico - chemical Param eters Molecular weight 437 . 14 g/mol 44262826 421 .1 g/mol 44262826 453 .15 g/mol 44262826 389 .09 g/mol 44262826 Vapor pressure (at 25  C) 7.5 × 10 - 8 torr 47723916 1.7 × 10 - 8 torr 44262803 5.7 × 10 - 9 torr 44262802 3.0 × 10 - 8 torr 44262801 Water so lubility (at 20  C) 2. 3 mg/L 47723915 No Data 0.16 mg/L 44350001 0.95 mg/L 44350002 Henry’s law constant (at 25  C) 5.2 × 10 - 13 atm - m 3 /mol (calculated) No Data 2.7 × 10 - 1 5 atm m 3 /mol (calculated) 9.6 × 10 - 1 4 atm m 3 /mol (calculated) Octanol
- air partition co efficient (KOA) (at 25  C) 11.463 EpiSuite v4.00 Not Estimated Not Estimated Not Estimated Octanol
- to - water partition coefficient (log P OW) 3.5 44350003 No Data 3.8 44350004 3.4 44350005 Persistence Hydroly sis half

- lives (20  C) Stable pH 5 Stable pH 7 28 d pH 9 42977905 No Data No Data No Data Aqueous photolysis half

life 0.33 d 42918661 No Data No Data No Data Soil photolysis half

- life 34 d 42918662 No Data No Data No Data Aerobic soil metabolism half
- life sandy loam 128 d

sand 308 d 42918663 No Data No Data loamy sand I 630 d loamy sand II 693 d 44262830 Aerobic aquatic metabolism half

- life sandy loam 14.5 d

Ongar 35.5 d Manningtree 16.42 d 44261909 44661301 44661301 No Data No Data No Data Anaerobic aquatic metabolism half

- life 160 d (total system) 43291704 No Data No Data No Data

### Page 14 of 71 Fipronil Fipronil S ulfide (MB 45950) Fipronil S ulfone (MB 46136) MB 46513 Param eter Value(s) Source (M RID) Value(s) Source (M RID) Value(s) Source (M RID) Value(s) Source (M RID) Soil Mobility Organic carbon
normalized adsorption coefficient (KOC ) 1248 mL/ g 800 mL/g 673 mL/g 427 mL/g 486 mL/g 44039003 5621 mL/ g 3530 mL/ g 4362 mL/ g 4349 mL/ g 1695 mL/ g 44537902 5310 mL/ g 4054 mL/ g 6745 mL/ g 1 448 mL/ g 3486 mL/ g 44537901 1150 mL/ g 1498 mL/ g 1164 mL/ g 1245 mL/ g 1392 mL/ g 44262831 Dissipation

Terrestrial field dissipation half

- life (soil texture or crop ) 1.1 months (FL bare sand) 0.4 months (FL turfed sand) 1.5 months (NC bare loamy

sand) 1.5 months (NC turfed sand) 3.4 months (loam soil) 3.0 months (clay loam) 3.8 months (sand) 7.3 months (loamy sand) 159 d (CA cotton) 30.2 d (TX cotton) 192 d (WA potato) 44078601

43401103
44262826 No Data No Data No Data

Aquatic field dissip ation half
- life (soil texture or crop ) Seed Treatment: 14.6 d ( MS loam) 12.6 d ( TX sandy loam) 11.9 d ( CA clay) Soil Pre
-plant Incorporated: 17.4 d ( MS loam) 18.8 d ( TX sandy loam) 119 d ( CA clay) 44443402 No Data No Data No Data

### Page 15 of 71 Fipronil Fipronil S ulfide (MB 45950) Fipronil S ulfone (MB 46136) MB 46513 Param eter Value(s) Source (M RID) Value(s) Source (M RID) Value(s) Source (M RID) Value(s) Source (M RID) Fish bioconcentration fac tors (BCF) 164 × (edible) 575 × (non
- edible) 380 × (w hole fish) 43291706 No Data No Data No Data

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### Abiotic Degradation The chemical degradation of fipronil appears to be dependent predomina nt ly on photodegradation in water and, to a lesser extent, on alkaline - catal yz ed hydrolysis. Fipronil is stable (t 1/2 

### > 30 days) in pH 5 and pH 7 buffer solution and hydroly zes slowly (t 1/2 

### =28 days) in pH 9 buffer solution. The major hydrol ys is degradate is RPA 200766 (5
- amino
- 3 - carbamo yl
- 1 - (2,6
- dichloro
- 4 - trifluoromethylph enyl )
- 4 - trifluoro
- methanesulfinyl py razole. Photodegradation of fipronil is a major route of degradation (photodegradation in water half

- life=3.63 hours) in aquatic environment. In contrast, fipronil photodegradation on soil surfaces (dark control correcte d half
- life=149 days) does not appear to be a major degradation pathway . Major photolysis products of fipronil are MB 46513 (5
- amino
- 3 - cyano - 1 - (2,6
- dichloro
- 4 - trifluoromethyl
- phenyl)
- 4 - trifluoro
methylpy razole 350, and RPA 104615 (5
- amino
- 3 - cyano - 1 - (2,6
- di chloro
- 4 - trifluoro methyl phenyl ) p yr azole
- 4 - sulfonic acid). Biotic Degradation Fipronil degradation in terrestrial and aquatic s ys tems appears to be controlled by slow microbially
- mediated processes. In aerobic mineral soil, fipronil is moderately persi stent to persistent (t 1/2 

### = 128 to 300 day s). Major aerobic soil degradates (>10% of applied of fipronil) are RPA 200766 and MB 46136 (5
- amino
- 1 - (2,6
- dichloro
- 4 - trifluoro methylphenyl )
- 3 - cyano - 4 - trifluoromethyl
- sulphonyl
-py razole). Minor degradates (<10% of applied fipronil) are MB 45950(5
- amino
- 1 - (2,6
- dichloro
- 4 - trifluoromethylphenyl)
- 3 - cyano - 4 - trifluoro
- methyl
- thio
-py razole) and MB46513. These degradation products are not unique soil metabolism degradation products. Fipronil degraded (t 1/2 

### =14.5 days to 35 days) under stratified redox aquatic/sediment systems. Fipronil also is moderatel y persistent (anaerobic aquatic t 1/2 

### = 116 - 130 days) in anoxic aquatic environments. Major anaerobic aquatic degradates are MB 45950 and RPA 200766. Supplemental aerobic aquatic metabolism data indicate that fipronil degradation (t 1/2 

### =14 days) is rapid in aquatic environments with stratified redox potentials. These data contradict the longer fipronil persistence reported in anaerobic aquatic and aerobic soil studies. Mobility Fipronil has a moderate sorption affinity (Kf 

### =4.19 to 20.69 mL/g; 1/n= 0.938 to 0.969; Koc 

### = 427 to 1248 mL/g) on five non
- United States soils (FAO mobility class: s lightly mobile ) . Fipronil sorption appears to be lower (Kf 

### < 5 mL/g) on coarse
- textured soil s with low organic matter contents. Desorption coefficients for fipronil ranged from 7.25 to 21.51 mL/g . These data suggest that fipronil sorption on soil is not a completely reversible process. Since the fipronil sorption affinity correlates with soil org anic matter content, fipronil mobility may be adequatel y described using a Koc 

### partitioning model. Soil column leaching studies confirm the immobility of fipronil.

### Page 17 of 71



### Terrestrial Field Dissipation Terrestrial field studies confirm observations of the relative persistence and immobility of fipronil residues in laboratory studies. Fipronil, formulated as a 1% granular, had half
lives of 1.1 to 1.5 months on bare ground in North Carolina (NC) and Florida (FL), 0.4 to 0.5 months on turf in NC and FL, and 3.4 to 7.3 months for in
- furrow applications on field corn in California (CA), Nebraska (NE), NC, and Washington (WA). Fipronil, formulated as 80WG and applied as a foliar spray at 0.3 lbs ai/A, had a field dissipation half
- life of 159 day s on a cotton site in Cal ifornia, 30.2 days on a cotton site in Washington, and 192 days on a potato site in Washington. The fipronil degradates MB 46136, MB45950, and RPA 200766 were detected in the field studies for in
- furrow and turf uses. The degradate MB46513 was detected during field trials with the foliar spray . Fipronil residues were predominantly detected in the 0 to 15 cm soil depth at all test sites. However, there was detection of fipronil, MB 45950, MB 46136 and RPA 200766 at a depth of 15 to 45 cm for in
- furrow treatments on coarse sandy loam soil in Ephrata, Washington. Although the field dissipation half
- life of individual residues was not reported, the half
- life of combined fipronil residues (including fipronil, MB 46136, MB 46513, MB 45950, and RPA 200766) ranged from 9 to 16 months. Long - term field dissipation studies in Nebraska, Illinois, Ohio, Mississippi, Texas, and Washington show fipronil, applied at 0.13 to 0.20 lbs ai/A as a broadcast application with soil incorporation or foliar spray , is moderatel y pers istent (t 1/2 

### = 5.1 to 144.4 days) in surface soils. There was no discernable ye ar - to - ye ar accumulation of MB46513. There was year- to - ye ar soil accumulation of MB 45950 and MB 46136. There were no detectable patterns of movement of fipronil residues except for MB46136. MB46136 was detected below 0.15 meter soil layer at all test sites except IL. The major routes of fipronil dissipation were through microbial
- mediated oxidation to form MB46136, microbial
- mediated reduction to MB45950, and photodegradation to form MB 46513. Aquatic Field Dissipation Fipronil residues were detected in soil samples in the California, Mississippi, and Texas field studies. Fipronil had calculated half
- lives of 14.6 day s (r2 

### =0.9 4) and 17.4 days (r2 

### =0.92 ) for Mississippi dry seedin g and pre -plant incorporated ( PPI) treatments, 12.6 days (r2 

### =0.53) and 18.8 day s (r2 

### =0.85) for Texas dry seeding, an d PPItreatments, and 11.9 day s (r2 

### =0. 9 4) and 119 day s (extrapolated) fo r California w et seeding and PPI treatment , respectivel y. The calcul ated half
- lives for combined Fip ronil residues (fipronil, MB 46513, MB 45950, MB 46136, and RPA 200766) are 35.0 day s (r2 

### =0.67) and 97.6 days (r2 

### =0.63) for Mississippi dry seeding and PPI treatments, 99.0 day s (r2 

### =0.19) and 34 7 days (r2 

### =0.28) for Texas dry seeding and PPItreatments, and 210 days (r2 

### = 0.20 ) and 257 (r2 

### =0.41) days for California wet seeding and PPItreatments . (MRID 44443402 ) Bio concentration in Fish

### Page 18 of 71



### The bioconcentration factor for radio labeled fipronil was 3 80× in whole fish, 164 × in edibl e tissues, and 575 × in non
- edible tissues. Accumulated fipronil residues were eliminated (>96%) after a 14
- day depuration period. Because fipronil exhibited a high depuration rate, fipronil is not expected to accumulate under flowing water conditions. Environmental Fate of Fipronil Degradates Because discernable decline patterns for the fipronil degradates were not observed in laboratory

metabolism studies, the degradates are believed to be persistent (t 1/2 

###  700 days) to microbially

mediated degradation in terrestrial and aquatic environments. However, the fipronil degradate, MB46136, rapidl y photodegrades (t 1/2 

### =7 days) in water. Radiolabelled MB 46513, applied at 0.1 μg/g, had an extrapolated half
- life of 63 0 or 693 days in loamy sand soils when incubated aerobically in the dark at 25 o C. The major metabolite of MB 46513 was RPA 105048(5
- amino
- 3 - carbamo yl
- 1 - (2,6
- dichloro
- 4 - trifluoromethylphenyl)
- 4 - trifluoromethylsulfonyl py razone). Fipronil degradation produ cts have a relativel y low potential mobility because of a moderate to high sorption affinity to soil organic matter. Organic carbon partitioning coefficients for fipronil degradates can range from 1150 to 1498 m l/g for MB 46513, 1619 to 3521 m l/g for MB 45 950, and 1448 to 6745 m l/g for MB 46136. The high sorption affinity

of fipronil degradation products is expected to limit movement into ground and surface water (FAO Classification of mobility is “hardl y mobile” for parent and all degradates). 

# IV . Recept ors Consistent with the process described in the Overview Document (USEPA 2004), the risk assessment for fipronil will rely on a surrogate species approach. T oxicological data generated from surrogate test species, which are intende d 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 pesticide registrants along with the available open literature are used to evaluate the potential direct and indirect effects of fipronil on aquatic and terrestrial receptors. This includes toxicity data on the technical grade active ingredient, degradates, and when available, formulated products ( e.g . , “Six
- Pack” studies). The open literature studies are identified using EPA’s ECOTOX database (USEPA 2007), which emplo ys a literature search engine for locating chemical toxicity

data for aquatic life, terrestrial plants, and wil dlife. The evaluation of both sources of data can also provide insight into the direct and indirect effects of fipronil on biotic communities from loss of species that are sensitive to the chemical and from changes in structure and functional characteristics of the affected communities. The ECOTOX database was searched in 2007 and data discovered during that search is summarized herein. The Agency intends to conduct an updated search of the database prior to initiation of the draft risk assessment.

### Page 19 of 71



### The e ffects section of this document summarizes the endpoints used in past fipronil risk assessments. Table 2 below describes the test species surrogate applications to various receptor taxonomic categories. Table 3 . Test Species Eval uated for Assessing Potential Ecological Effects of Fipronil and the Associated Acute Toxicity Classification . Taxonomic Group Surrogate Species Acute Toxicity

-- Chronic Toxicity Birds 1 Bobwhite quail ( Colinus virginianus ) 1 - day LD 50 8 - day LC 50

-- Repro duction NOAEC Mammals Laboratory rat ( Rattus norvegicus) 96 - hr LD 50

-- Reproduction NOAEC/LOAEC Insects Honey bee ( Apis mellifera L. ) Extended contact 72 hr
Freshwater fish 2 Bluegill sunfish ( Leponis macrochirus)

-- Rainbow trout ( Oncorynchus mykis ) ACR applied to bluegill 96 -hr LC 50

-- ACR- based NOAEC
Freshwater invertebrates Blackfly (Simulium vitta tum )

-- Water flea (

Daphnia magna ) ACR applied to blackfly 48 -hr EC 50

-- ACR- based NOAEC/LOAEC Estuarine/marine fish Sheepshead minnow ( Cyprinodont variegatus ) 96 -hr L C 50

-- NOAEC/LOAEC Estuarine/marine invertebrates Mysid ( Americ amysis bahia ) Eastern oyster ( Crassostrea virginica ) 96 -hr LC 50

-- NOAEC/LOAEC Terrestrial plants 3 Seedling Emergence (no data) Vegetative Vigor (no data) EC 25 /NOAEC Aquatic plants and al gae Diatom ( Navicula pelliculosa ) Duckweed ( Lemna gibba ) 5 - day EC 50 NOAEC

-- 14 - day EC 50 NOAEC 

## A. Effects to Aquatic Organisms Fipronil parent has been tested for acute effects in three species of fish with acute lethal endpoints ranging from 83 to 56 0 μg/L . Acute affects testing for freshwater invertebrates is available on at least 25 species and acute lethal endpoints range from 0.22 μg/L to >2000 μg/L. Available acute fish toxicity data for the three degradates of concern fall within these ranges in toxicity, though the number of species tested is far less than for the

### Page 20 of 71



### parent compound. There are limited species tested in estuarine /marine organisms, but the invertebrate and fish endpoints are close to the range established for freshwater organisms . Chronic effects thresholds for fish are generall y a half to two orders of magnitude lower than acute effects depending on the within species comparison made. In invertebrates, chronic effects endpoints are approximately an order of magnitude lower than the acute effects endpoint. There are sediment toxicity data available for select midge species, but the effects in these species are quite similar to water onl y exposure - based effects endpoints in similar midge species. Aquatic plant toxicity

data are available to parent fipronil and with five species with no effects thresholds of 100 to 140 μg/L . Only the degradate MB46513 has been tested with aquatic plants and it is more potent than parent fipronil in the single species tested common to both chemical s. Owing to this potential difference and potential for degradates to be more potent than the parent, additional tier 1 aquatic plant testing (850.440 and 5400) is recommended. 

## B . Effects to Terrestrial Organisms Fipronil has been tested in six species of birds for acute effects, including one passeriform species. The range in acute lethal endpoints is 11.3 to >2150 mg/kg
- bw. The degradate MB46513 is the only degradate tested with birds, and within species comparisons suggest that the degradate is 2 to at least 5 times more acutely toxic than the parent. Sublethal dietary

testing with the parent compound has been conducted in two species with the range in values of 48 to >5000 mg/kg - diet. Testing with all three degradates of concern with a species rep resented by the parent data set indicates the degradates are slightl y less toxic than the parent via the dietary route. Chronic effects endpoints have only

been empirically

determined for the parent, but the relationship between acute and chronic endpoint s for the parent has been routinel y applied to the degradate acute data to derive chronic endpoints. Acute and chronic mammalian data with the rat are the basis for mammalian wildlife risk assessment. Fipronil and MB45950 are relatively close in acute lethal potency with endpoints of 97 and 83 mg/kg
- bw respectively . MB46136 is less toxic than the parent with an acute lethal endpoint of 218 mg/kg
- bw and MB46513 is more toxic to rats than parent with an acute lethal endpoint of 16 mg/kg
- bw. Only the parent has been tested for reproduction effects in mammals, but the relationship between acute and chronic endpoints for the parent has been routinel y applied to the degradate acute data to derive chronic endpoints. Terrestrial invertebrate testing is limited to a single honey bee extended foliar contact study showing an endpoint of 100 % mortality at a 25 g/ a application rate. Acute contact and field studies are recommended for a more complete characterization of risks to insect pollinators.

### Page 21 of 71



### Tier 1 plant effe cts testing data are not available for fipronil products. Studies to provide suitable seedling emergence and vegetative vigor effects endpoints are recommended. 

## C
. Degradate toxicity Based on an analy sis of available toxicity information and the preval ence of degradates in one or more environmental fate studies , the stressor of concern in the assessment include the parent (fipronil) and degradates: fipronil sulfide (MB 45950; CAS name: 5
- amino
- 1 - (2,6
- dichloro
- 4 - (trifluoromethyl)phenyl )
- 4 - trifluoromethylthio
- 1 - py razole
- 3 - carbonitrile); fipronil sulfone (MB 46136; CAS name: 5 - amino
- 1 - (2,6
- dichloro
- a,a,a trifluoro
-p - tolyl)
- 4 - trifluoro
- methylsulfonylpy razole
- 3 - carbonitrile) ; MB 46513 ( CAS name: 5 - amino
- 1 - (2,6
- dichloro
- alpha,alpha,alpha
- trifluoro
- p - tolyl)
- 4 - trifluoro
methylpy razole
- 3 - carbonitrile ). 

## D . Ecological Incidents There are few incidents in the Agency database for effects on non
- target organisms associated with the labeled use of fipronil. The degree to which the low number of ye ars of outdoor use contributes to a lack of incidents is unknown. In cident number I009142001 is a report of crayfish mortality following use of fipronil as a seed treatment on rice in L ouisiana. The database classifies this incident as highl y probable. In March of 1999 L ouisiana Department of Agriculture and Safety issued a stop order to prevent the use of fipronil on rice seed in Allen, Calcasieu, Cameron, Lafayette, St. Martin, Iberia, St. Mary , St. L andry , Beauregard, Vermillion, Evangeline, Acadia, and Jefferson Davis Parishes. Fipronil was detected in 3 of 9 crawfish samples (mean detection 0.04 μg/kg). Fipronil was detected in water samples from 8 of 16 ponds (average 2.08 μg/L, high 6.09 μg/L), in all samples of the Mermentau River (average 1.67 μg/L, high 3.16 μg/L), and 14 of 17 other water monitoring sites (average 0.84 μg/L, high 5.33 μg/L). the registrant (Rhone
- Poulenc reported that 17 crawfish growers had reported to them observations of crawfish at the edges of ponds bordering rice fields planted with fipronil
- treated rice. The LA department of Agriculture was investigating 31 reported incidents of crawfish kills on rice. Among the department and registrant reports there were 45 total incidents. The Louisiana state university Agricultural center conducte d a survey

and several experiments which substantiated the link between fipronil
- treated rice seed and reduced survival of crawfish under hot dry weather conditions. Fipronil is no longer registered for rice seed treatment. There are two reports of corn crop damage (I011723098 300 acres in North Dakota, and I013103054300 550 acres in I daho) following use of fipronil Regent SC. These incidents are classified in the database as possible (Idaho incident) and probable (North Dakota). In neither incident repo rt are there any confirmatory residue analyses.

### Page 22 of 71



### Another probable incident, outside the United States, is also reported in the Agency database. Itinvolves locust control efforts on the island of Madagascar (I010380001). The incident was summarized in a BBC news article. The article refers to survey results citing declines in the Madagascar bee eater and a kestrel species. In addition, surveys of termite colonies showed a 90% elimination rate ten months after spraying. There are no confirmatory

anal yti cal data reported in the incident summary . Finally , incident I010775001 reported that fipronil treated sunflower seeds were potentially

responsible for observations of honey bee hive mortality in France. This incident is controversial as another, commonly accepted to be s ys temic pesticide, was also implicated. The incident report includes no third party confirmation or refutation of the fipronil alleged involvement in the incident. 

## D
. Ecosystems Potentially at Risk The ecos ys tems potentially at risk are often extensive in scope; therefore, it may not be possible to identify

specific ecos ys tems during the development of a nation
- wide ecological risk assessment. However, in general terms, terrestrial ecos ys tems potentially at risk could include the treated field and immediately adjacent areas that may

receive drift or runoff. Areas adjacent to the treated field could include cultivated fields, fencerows and hedgerows, meadows, fallow fields or grasslands, woodlands, riparian habitats, and other uncultivated areas. Aquatic ecos ys tems potentially at risk include water bodies adjacent to or downstream from the treated field and might include impounded bodies such as ponds, lakes and reservoirs, or flowing waterway s such as streams or rivers. For uses in co astal areas, aquatic habitat also includes marine ec os ys tems, including estuaries. 

# V. As sessment End points Assessment endpoints represent the actual environmental value that is to be protected, as defined b y an ecological entity (species, community , or other entity) and its attribute or characteristics (EPA 1998). For fipronil, the ecological entities include the following: birds, reptiles, terrestrial
- phase amphibians, mammals, freshwater fish, freshwater aquatic
-phase amphibians and invertebrates, es tuarine/marine fish and invertebrates, terrestrial plants, insects, aquatic plants, and algae. The attributes for each of these entities include growth, reproduction, and survival. 

# VI. Conceptual Model For a pesticide to pose an ecological risk, it must reach ecological receptors in biologicall y significant concentrations. An exposure pathway is the means by which a

### Page 23 of 71



### pesticide moves in the environment from a source to an ecological receptor. For an ecological pathway to be complete, it must have a source, a release mechanism, an environmental transport medium, a point of exposure for ecological receptors, and a feasible route of exposure. The conceptual model for fipronil provides a written description and visual representation of the predicted relationships between fipronil, potential routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model consists of two major components: risk hy

pothesis and a conceptual diagram (USEPA 1998). 

## A . Risk Hypothesis A risk hy pothesis describes the predicted relationship among the stressor, exposure, and assessment endpoint response along with the rationale for their selection. For fipronil, the following ecologi cal risk hy pothesis is being employed for this national
- level ecological risk assessment: Fipronil, when used in accordance with current labels, can result in off
-site movement of the compound via runoff, erosion of sediment
- bound residues and spray drift leading to exposure of nontarget plants and animals. Applications to foliar surfaces may serve as a major source of fipronil exposure to wildlife. This potential exposure pathway may result in adverse effects upon the survival, growth, and reproduction of non
- target terrestrial and aquatic organisms. These nontarget organisms include Federally
- listed threatened and endangered species. 

## B. Conceptual Diagram The environmental fate properties of fipronil indicate that runoff, erosion of sediment
bound residues, and spray drift represent potential transport mechanisms of fipronil to aquatic and terrestrial organisms. These transport mechanisms ( e.g . , sources) are depicted in the conceptual models below ( Figures 5 and 6 ) and re sult in the movement of fipronil into aquatic (water and sediment) and terrestrial (soil and foliage) habitats. The movement away

from the site of application in turn represents exposure pathway s for a broad range of biological receptors of concern (nontarget animals) and the potential attribute changes, i.e. , effects such as reduced survival, growth and reproduction, in the receptors due to fipronil exposure.

### Page 24 of 71

Figure 5 . Conceptual m odel depicting str essors, exposure pathways, and potential effects to aquatic organisms fromthe use of fipronil . Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk. ** Route of exposure includes only ingestion of fish and aquatic 

## Stressor Source

Receptors

At tribute Change Fipronil applied to use site

Spray drift

Aq uatic animals Invertebrates Ve rtebrates **Piscivorous mammals and birds Individual organisms Reduced survival Reduced growth Reduced Food chain Reduction in algae and vascular plants Reduction in prey Modification of PCEs related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Community change Modification of PCEs related to habitat Surface water/ Sediment Runoff

Aq uatic A nimals I nvertebrates Vertebrates 

## Exposure Media
Uptake/gills

or integument Ingestion Ingestion Atm ospheric transport
We t/dry deposition Soil Leaching to

Groundwater

Uptake/gills or integument Aq uatic Plants

Non - vascular Vascular Uptake/cell, roots, leaves Riparian plants te rrestrial exposure pathways see Figure 6

### Page 25 of 71

Figure 6 . Conceptual m odel depicting stressors, generic exposure pathways, and potential effects to terrestrial organism s (terrestrial plants, terrestrial invertebrates, and dietary routes of exposure for terrestrial vertebrates) from the use of fipronil. Dotted lines indicate expos ure pathways that have a low likelihood of contributing to ecological risk. 

# VII. An al ys is Plan In order to address the risk hy pothesis, the potential for adverse effects on the environment is estimated. The use, enviro nmental fate, and ecological effects of fipronil are characterized and integrated to assess the risks. This is accomplished using a risk quotient (ratio of exposure concentration to effects concentration) approach. Although risk is often defined as the l ikelihood and magnitude of adverse ecological effects, the risk quotient
- based approach does not provide a quantitative estimate of likelihood and/or magnitude of an adverse effect. However, as outlined in the Overview Document (USEPA 2004), the likelihoo d of effects to individual organisms from particular uses of fipronil is estimated using the probit dose
- response slope and either the level of concern (discussed below) or actual calculated risk quotient values. Stressor Source

Attribute Change Fipronil applied to use site

Direct application Spray drift

Terrestrial vertebrates Terrestrial inverts

Individual organisms Reduced survival Reduced growth Reduced reproduction Food chain Reduction in prey and food Modification of PCEs related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Community change Modification of PCEs related to habitat Terrestrial plants grasses/forbs, fruit, seeds (trees, shrubs) Runoff

Terrestrial Vertebrates 

### Exposure Media & Receptors Soil

Ingestion Ingestion Ingestion Dermal uptake/Ingestion Atmospheric transport

Root uptake/contact

We t/dry depositi on

Ingestion Leaching to

Groundwater Irrigation water

### Page 26 of 71



### This analysis plan will be revisited and m ay be revised depending upon the information submitted by

the public in response to the opening of the Registration Review docket for fipronil. 

## A . Stressors of Concern Based on an analysis of available toxicity information and the prevalence of degradate s in one or more environmental fate studies the stressor of concern in the assessment include the parent (fipronil) plus the following degradates: MB 45950 Fipronil Sulfide CAS name: 5 - amino
- 1 - (2,6
- dichloro
- 4 - (trifluoromethyl)phenyl )
- 4 - trifluoromethylthio
- 1 - py razole
- 3 - carbonitrile MB 46136 Fipronil Sulfone CAS name: 5 - amino
- 1 - (2,6
- dichloro
- a,a,a - trifluoro
-p - tolyl)
- 4 - trifluoro
methylsulfonylpy

razole
- 3 - carbonitrile MB 46513 CAS name: 5 - amino
- 1 - (2,6
- dichloro
- alpha,alpha,alpha
- trifluoro
-p - tolyl)
- 4 - trifluoro methylpy razole
- 3 - carbonitrile Evaluation of environmental pesticide mixtures is beyond the scope of this assessment because of the myriad factors that cannot be quantified based on the available data. Those factors include identification of other pos sible co
- contaminants and their concentrations, differences in the pattern and duration of exposure among contaminants, and the differential effects of other phys ical/chemical characteristics of the receiving waters ( e.g. , organic matter present in sediment and suspended water). Evaluation of factors that could influence additivity /sy nergism is beyond the scope of this assessment and the capabilities of the available data to allow for an evaluation. However, it is acknowledged that not considering mixture s could over
- or under
- estimate risks depending on the type of interaction and factors discussed above. The assessment will, however, anal yz e the toxicity of formulated products (including formulations involving more than one active ingredient) and will determine whether formulated products are more toxic than the technical grade active ingredient. 

## B. Measures of Exposure In order to estimate risks of fipronil exposures in aquatic and terrestrial environments, all e xposure modeling and resulting risk conclusions will be based on maximum application rates and methods cited in Table 1 (of Appendix 1 ) and will be estimated for each use of fipronil. Measures of exposure are base d on aquatic and terrestrial models that predict estimated environmental concentrations (EECs) of fipronil. The models used to predict aquatic EECs are the Pesticide Root Zone Model coupled with the Exposure Anal ys is Modeling S ys tem (PRZM/EXAMS). The mod el used to predict terrestrial EECs on food

### Page 27 of 71



### items is T
- REX. The model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant. These models are parameterized using relevant reviewed environmental fate data from registrant submissions and the literature; model input values will be consistent with the most recent version of the input parameter guidance (Version 2; EFED 2002). PRZM and EXAMS are simulation models coupled with the linkage program shell, PE5, which incorporates the standard scenarios developed by EFED. The models generate daily exposures and calculated 1
- in
- 10 year EECs of fipronil ( and degradates of concern) that may occur in surface water bodies adjacent to application sites. PRZM simulates pesticide fate and transport as a result of leaching, direct spray drift, runoff and erosion from an agricultural field, and EXAMS estimates environmental fate and transport of pesticides in a surface water body for a 30
- ye ar period. The standard scenarios used for ecological pestici de assessments assume application to a 10
- hectare agricultural field that drains into an adjacent 1
- hectare water body that is 2 meters deep (20,000 m 3 

### volume) with no outlet. The combined models ( i.e. , PRZM/EXAMS ) are designed to estimate pesticide concentrations found in the water body (standard pond) at the edge of the treated field. As such, they provide high
- end values of the pesticide concentrations that might be found in ecologically sensitive environments following pesticide application. The location of the field is specific to the crop being simulated using site
- specific information on the soils, weather, cropping, and management factors associated with the scenario. The crop/location scenario is intended to represent a high
- end exposure site on which the crop is normally grown. Based on historical rainfall patterns, the receiving water body receives multiple runoff events during the years simulated. Weather and agricultural practices are simulated for 30 years so that the 10
- ye ar exceedance probability

at the site can be estimated. The simulation is generated using 30 years of meteorological data, ty

pically , encompassing the years from 1961 to 1990. Additional information on these models can be found at: http://www.epa.gov/oppefed1/models/water/index.htm . To estimate exposure related to releases of fipronil and its degradates through domestic wastewater treatment plants, the Agency will rel y on the Office of Pollution Preventi on and Toxics (OPPT) model, Exposure and Fate Assessment Screening Tool (EFAST, version 2.0, or EFAST2, 2007). From this model, the Agency will use the “Down
- the
Drain” module, which is designed for releases to domestic wastewater treatment. It is suitabl e for all the sources of fipronil and its degradates that could potentially be exposed through a “down
- the
- drain” scenario. The model provides screening level estimate concentrations of chemicals in surface water that may result from household uses and th e disposal of consumer products into wastewater using a few simple input parameters (production volume and fraction of the chemical removed during wastewater treatment). The measure of exposure for aquatic species is the 1
- in
- 10 year return peak or rolling mean concentration. The 1
- in
- 10 year peak is used for estimating acute exposures of direct effects to aquatic organisms. The 1
- in
- 10 - year 60 - day mean is used for assessing chronic exposure to fish and aquatic
-phase amphibians. The 1
- in
- 10 - ye ar 21 - day mean is used for assessing chronic exposure to aquatic invertebrates.

### Page 28 of 71



### Exposure estimates for terrestrial animals assumed to be in the target area or in an area exposed to spray

drift are derived using the T
- REX model. This model inc orporates the Kenega nomograph, as modified by Fletcher et al. (1994), which is based on a large set of field residue data. The upper limit values from the nomograph represent the 95 th 

### percentile of residue values from actual field measurements (Hoerger a nd Kenega 1972). The Fletcher et al. (1994) modifications to the Kenega nomograph are based on measured field residues from 249 published research papers, including information on 118 species of plants, 121 pesticides, and 17 chemical classes. EECs for t errestrial plants inhabiting dry and wetland areas are derived using TerrPlant. 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. Available monitoring data will be used to qualitatively characterize exposure and compare with modeling results. The Agency is aware of monitoring conducted by storm water management agencies and this route of exposure will be considered in the assessment to the extent that data on fipronil are available. Two spray

drift models, AGD ISP and AgDRIFT will be used to assess exposures of terrestrial plants to fipronil deposited in terrestrial habitats by spray drift. AgDrift will be used to simulate ground appli cations. 

## C . Measures of Effect Ecological effect data are used as measures of direct and indirect effects to biological receptors. Data were obtained from registrant
- submitted studies or from literature studies identified by

ECOTOX. The ECOTOXicology dat abase (ECOTOX) was searched in order to provide more ecological effects data 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 (USEPA 2007). In formation on the potential effects of f ipronil on non
- target animals is also collected from the Ecological Incident Information System (EIIS; USEPA 2007 c ). 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. Where available, sublethal effects observed in both registrant
- submitted and open literature studies wi ll be evaluated qualitatively . Such effects have included behavioral changes ( e.g. , lethargy , changes in coloration and effects olfaction). 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.

### Page 29 of 71



### The assessment of risk for direct effects to non
- target organisms makes the assumption that toxicity

of fipronil to birds is similar to terrestrial
-phase amphibians and reptiles . The same assumption is made for fish and aquatic
-phase amphibians. The acute measures of effect used f or animals in this screening
- level assessment are the LD 50 

### , L C 50 

### and EC 50 

### . LD stands for "Lethal Dose", and LD 50 

### 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 LC 50 

### is the concentration of a chemical that is estimated to kill 50% of the test organisms. EC stands for “Effective Concentration” and the EC 50 

### is the concentration of a chemical that is estimated to produce a specific effect in 50% of the t est 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 hav e no harmful (adver se) 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
- Observe d
- Effects
- Concentration. For non - listed plants, only acute exposures are assessed ( i.e. , EC 25 

### for terrestrial plants and EC 50 

### for aquatic plants); for listed plants, either the NOAEC or EC 05 

### is used. In the absence of data for either acute or chronic effe cts for fipronil or degradates of concern , the risk assessment will make conservative assumptions based on extrapolations from the existing available data. 

## D . Integration of Exposure and Effects Risk characterization is the integration of exposure and ec ological effects characterization to determine the potential ecological risk from the use of fipronil on forestry uses (forest tree management/forest pest management, forest trees (softwoods, conifers), and pine (forest/shelterbelt)); outdoor residential u ses (household/domestic dwellings outdoor premises, refuse/solid waste containers (garbage cans), and residential lawns); terrestrial food + feed crop uses (orchards (unspecified), potato and white/Irish); terrestrial non food + outdoor residential uses (f encerows/hedgerows, ornamental and/or shade trees, and paths/patios); and terrestrial non - food crop uses (Christmas tree plantations, commercial storages/warehouses premises, commercial/industrial lawns, commercial/institutional/industrial premises/equipment (outdoor), field corn, golf course turf, industrial / construction areas (outdoor), nonagricultural outdoor buildings/structures, nonagricultural uncultivated areas/soils, nursery stock, ornamental and/or shade trees, ornamental herbaceous plants, ornam ental lawns and turf, ornamental non - flowering plants, ornamental sod farm (turf), ornamental woody shrubs and vines, paved areas (private roads/sidewalks), potting soil/topsoil, recreation area lawns, recreational areas, refuse/solid waste sites (outdoor) , utility poles / right
- of

- way , wood protection treatment to buildings/products outdoor, and zoos and the likelihood of direct and indirect effects to non
- target organisms in aquatic and terrestrial habitats. The exposure and toxicity

effects data are int egrated in order to evaluate the risks of adverse ecological effects on non
- target species. For the assessment of fipronil risks, the risk

### Page 30 of 71



### quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are divided b y acute and chroni c toxicity values. The resulting RQs are then compared to the Agency ’s levels of concern (LOCs) (USEPA 2004). These criteria are used to indicate when fipronil’s uses, as directed on the label, have the potential to cause adverse direct or indirect effec ts to non - target organisms. As noted previousl y, where data are lacking on the toxicity

of fipronil, risk will be presumed. 1. Deterministic and Probabilistic Assessment Methods The quantitative assessment of risk will primarily depend on the determini stic point
estimate based approach described in the risk assessment. An effort will be made to further qualitativel y describe risk using probabilistic tools that the Agency has developed. These tools have been reviewed b y F IFRA Scientific Advisory Panels and have been deemed as appropriate means of refining assessments where deterministic approaches have identified risks. 

## E. Endangered Species Assessments Consistent with the Agency ’s responsibility under the Endangered Species Act (ESA), the Agency

wil l evaluate risks to Federally
- listed threatened and/or endangered (listed) species from registered uses of fipronil. 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 fipronil is based on an action area. The action area is considered to be the area directly or indirectl y affected b y the federal action, as indicated by the exceedance of Agency L evels 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 assessm ent 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 fipronil application occurs), plus all areas where offsite transport ( i.e. , spray

drift, runoff, etc.) may

result in potential exposure that exceeds the Agency ’s LOCs. Specific measures of ecological effect that define the action are a 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 sublethal effects available in the effects literature . Therefore, the action area extends to a point where environmental exposures are below any measured lethal or sublethal effect threshold for any biological entity at the whole organism, organ, tissue, and cellular level of organization. In situations wh ere 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.

### Page 31 of 71



## F. Drinking Water Assessment A drinking water assessment will be conducted to support future human health dietary risk assessments of fipronil. The drinking water assessment will incorporate model estimates of fipronil plus degradates of concern in surface water and ground water. Concentrations of fipronil residues in surface waters will be es timated using PRZM/EXAMS (see description above). An Estimated Drinking Water Concentration (EDWC) of fipronil residues in ground water will be estimated using EFED’s Tier I aquatic model SCI - GROW (Screening Concentration in Ground Water). SCI - GROW is a regression model used as a screening tool to estimate pesticide concentrations found in ground water used as drinking water. The output of SCI
- GROW represents the concentrations that might be expected in shallow unconfined aquifers under sandy soils, which is representative of the ground water most vulnerable to pesticide contamination likely to serve as a drinking water source. The drinking water assessment will also include available surface and ground water monitoring data with consideration of changes in use patterns that may have occurred. States are encouraged to submit monitoring data for review. 

## G. Preliminary Identification of Data Gaps As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor Screening Program (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 b y 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, and or thy roid (E, A, or T) hormonal sy stems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal s ys tems will proceed to the next s tage 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 b y the substance, and establish a dose
- response relationship between the dose and the E, A, or T effect. 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. This list of chemicals was selected based on the potential for human exposure through pathway s such as food and water, residential activity , and certain post
application agricultural scenarios. This list should not be construed as a list of known or likely endocrine di sruptors. Fipronil and its degradates of concern are not among the group of 58 pesticide active ingredients on the initial list to be screened under the EDSP. The Agency will review the EDSP Tier 1 data and any “other scientifically relevant information” submitted in

### Page 32 of 71



### response to test orders. Based on this review the Agency will determine the need for additional testing. For further information on the status of the EDSP, the policies and procedures, the list of 67 chemicals, the test guidelines and the Ti er 1 screening battery , please refer to the following website: http://www.epa.gov/endo/ . 

## H. Preliminary Identification of Data Gaps 1. Fate The environmental fate data set is complete for the parent fipronil ( Table 4 ). However, the fate data sets for the degradates of concern are incomplete. Fipronil sulfide (MB 45950) is formed as a major degrad ate of fipronil (greater than 10% of parent applied) in both terrestrial and aquatic laboratory studies and aquatic field, terrestrial field, long
- term soil dissapation studies . Therefore, both aquatic and terrestrial fate studies are needed for fipronil s ulfide ( Table 5 ) . Fipronil sulfone (MB 46136) only occurs as a major degradate in terrestrial fate and field studies . Because of concerns with accumulation in the terrestrial environment and runoff from terrestrial environments, both aquatic and terrestrial fate studies are needed for fipronil sulfone ( Table 6 ) . MB 46513 only occurs as a major degradate in aquatic fate studies. Therefore, aquatic fate studies are needed for MB 46513 ( Table 7 ) . (See Appendix 1 Table B for maximum reported amounts of fipronil degradation products from each fate study.) Table 4 . Available environmental fate data for fipronil and rem aining data gaps. 158 Guideline (OPPTS) Description Reference (MRID) Classification Data Gap? Comments 161 - 1 (835.2120) H ydrolysis 42194701 Acceptable No 161 - 2 (835.2240) Photodegradation

in water 42918661 Acceptable No 161 - 3 (835.2410) Photodegradation

on soil 42918662 Acceptable No 162 - 1 (835.4100) Aerobic soil

metabolism 42918663

44262830 Acceptable

Acceptable No 162 - 2 (835.4200) Anaerobic soil

metabolism None Submitted Yes In absence of acceptable data, 2× the aerobic soil metabolism rate will be used in exposure assessment. 162 - 3 (835.4400) Anaerobic Aquatic

Metabolism 43291704 Acceptable No 162 - 4 (835.4300) Aerobic Aquatic

Metabolism 44261909

44661301 M arginally acceptable No Conducted in stratified redox conditions .

### Page 33 of 71 158 Guideline (OPPTS) Description Reference (MRID) Classification Data Gap? Comments 163 - 1 (835.1230) (835.1240) Leaching and

adsorption/ desorption 42918664

43018801 44039003 44262831 44537901 44537902 44537903 Acceptable

Accep table Acceptable Acceptable Acceptable Acceptable Acceptable No

164 - 1 (835.6100) Terrestrial Field

Dissipation 43291705

43401103 44262826 44262827 44298001 Acceptable

Acceptable Acceptable (supplemental material) (supplemental material) No

164 - 2 Aquati c field

dissipation 44443402

45344701 46016801 Acceptable

Acceptable Acceptable No
164 - 5 Long term soil

dissipation 44952701

45279901 46038001 46477001 Acceptable

Acceptable Acceptable Acceptable No

165 - 4 (850.1730) Bioaccumulation in

Fish 43291706

432 91707 44298002 Acceptable No 165 - 5 Bioaccumulation in

aquatic non
- target organisms 45183601 Acceptable No

Table 5 . Available environmental fate data for fipronil sulfide ( MB 54950 ) and remaining data gaps. 158 Guideline (OPPTS ) Description Reference (MRID) Classification Data Gap? Comments 63 - 8 ( 830.7840 ) Water Solubility None Yes 161 - 1 (835.2120) Hydroly sis None Yes 161 - 2 (835.2240) Photodegradation

in water None Yes 161 - 3 (835.2410) Photodegradation

on soil None Ye s 162 - 1 (835.4100) Aerobic soil

metabolism None Yes 162 - 2 (835.4200) Anaerobic soil

metabolism None Yes 162 - 3 (835.4400) Anaerobic Aquatic

Metabolism None Yes 162 - 4 (835.4300) Aerobic Aquatic

Metabolism None Yes

### Page 34 of 71 158 Guideline (OPPTS ) Description Reference (MRID) Classification Data Gap? Comments 163 - 1 (835.1230) (835.1240) Le aching and

adsorption/ desorption 44537902 Acceptable No
164 - 1 (835.6100) Terrestrial Field

Dissipation None Yes 165 - 4 (850.1730) Bioaccumulation in

Fish None Yes
Table 6 . Available environmental fate data for fipronil su lfone (MB 46136) and remaining data gaps. 158 Guideline (OPPTS) Description Reference (MRID) Classification Data Gap? Comments 161 - 1 (835.2120) Hydroly sis None Yes 161 - 2 (835.2240) Photodegradation

in water None Yes 161 - 3 (835.2410) Photodegradation

on soil None Yes 162 - 1 (835.4100) Aerobic soil

metabolism None Yes 162 - 2 (835.4200) Anaerobic soil

metabolism None Yes 162 - 3 (835.4400) Anaerobic Aquatic

Metabolism None Yes 162 - 4 (835.4300) Aerobic Aquatic

Metabolism None Yes 163 - 1 (835.12 30) (835.1240) Leaching and

adsorption/ desorption 44537901 Acceptable No 164 - 1 (835.6100) Terrestrial Field

Dissipation None Yes 165 - 4 (850.1730) Bioaccumulation in

Fish None Yes
Table 7 . Available environmental fate data for MB46513 and rem aining data gaps. 158 Guideline (OPPTS) Description Reference (MRID) Classification Data Gap? Comments 161 - 1 (835.2120) Hydroly sis None Yes 161 - 2 (835.2240) Photodegradation

in water None Yes

### Page 35 of 71 158 Guideline (OPPTS) Description Reference (MRID) Classification Data Gap? Comments 161 - 3 (835.2410) Photodegradation

on soil None No Occurs as a major degradate in aquatic fate studies only 162 - 1 (835.4100) Aerobic soil

metabolism 44262830 Acceptable No 162 - 2 (835.4200) Anaerobic soil

metabolism None No Occurs as a major degradate in aquatic fate studies only 162 - 3 (8 35.4400) Anaerobic Aquatic

Metabolism None Yes 162 - 4 (835.4300) Aerobic Aquatic

Metabolism None Yes 163 - 1 (835.1230) (835.1240) Leaching and

adsorption/ desorption 44262831 Acceptable No
164 - 1 (835.6100) Terrestrial Field

Dissipation None No Occur s as a major degradate in aquatic fate studies only 165 - 4 (850.1730) Bioaccumulation in

Fish None Yes 

### 2. Effects The following table presents the status of study submissions to comply

with 40 CFR Section 148 dat a requirements applicable to fip ronil and degradates of concern for the outdoor sues of the compound as formulated. Although many submissions have been made to provide data on the effects of fipronil and the three degradates of concern to aquatic and terrestrial o rganisms, gaps in experimental effects information still exist. With the exception of outstanding pollinator and plant testing there are no appreciable data gaps regarding laboratory testing for biological effects that have previously impacted the quantitative assessment of risks to the taxa that form the basis of risk assessment process described in the Overview of Ecological Risk Assessment process in the Office of Pesticide Programs (USEPA 2004) . Table 8 . Non - Target Organism Toxicity Data Gaps Test guideli ne Number Description Chemical Reference Classification Data Gap? Comments 850.2100 Avian oral Fipronil 42918617 42918618 acceptable no 2 MB46136 -- -- yes 1 MB46513 43776601 acceptable yes 3 MB45950 -- -- yes 1 850.2200 Avian dietary Fipronil 42918620 acceptable no

### Page 36 of 71

Test guideli ne Number Description Chemical Reference Classification Data Gap? Comments MB46136 44890301 acceptable no MB46513 4529201 acceptable no MB45950 44890302 acceptable no 850.2300 Avian

reproduction Fipronil 42918622/3 acceptable no

MB46136 -- -- yes 1 MB46513 -- -- yes 1 MB45950 -- -- yes 1 850.3020 Honey bee acute

contact Fipronil
-- -- yes

MB46136 -- -- yes MB46513 -- -- yes MB45950 -- -- yes 850.3030 Honey bee foliage

residue toxicity Fipronil 44884101 supplemental yes

MB46136 -- -- yes MB46513 -- -- yes MB45950 -- -- yes 850.3040 Field testing for

pollinators Fipronil
-- -- yes

MB46136 -- -- no 4 MB46513 -- -- no 4 MB45950 -- -- no 4 850.4100 Seedling

emergence Tier 1 Fipronil
-- -- yes

MB46136 -- -- no 4 MB46513 -- -- no 4 MB45950 -- -- no 4 850.4150 Vegetative vigor

Tier 1 Fipronil
-- -- yes

MB46136 -- -- no 4 MB46513 -- -- no 4 MB45950 -- -- no 4 850.1075 Freshwater fish

acute toxicity Fipronil 42977902 42918624 acceptable no MB46136 429218673

42918674 acceptable no MB46513 43279702

43291718 43279703 acceptable no MB45950 -- -- yes 1 850.1010 Freshwater

invertebrate acute toxicity Fipronil 42918625 acceptable no 5

MB46136 42918671 acceptable no MB46513 -- -- yes 5 MB45950 42918669 acceptable no 850.1300 Freshwater

aquatic invertebrate life cycle Fipronil 42918626 acceptable no

MB46136 -- -- yes 1 MB46513 43279704,

44812801 acceptable no MB45950 -- -- yes 1 850.1400 Freshwater fish

early life stage Fipronil 42918627 acceptable no

MB46136 -- -- yes 1 MB46513 -- -- yes 1 MB45950 -- -- yes 1 850.1025/1055 Oy ster acute Fipronil 3291701 acceptable no

### Page 37 of 71

Test guideli ne Number Description Chemical Reference Classification Data Gap? Comments toxicity/bivalve acute toxicity MB46136 -- -- yes

MB46513 -- -- yes MB45950 -- -- yes 850.1035 /1045 My sid acute

toxicity/penaeid shrinp acute toxicity Fipronil 43279701 acceptable no

MB46136 45156301 acceptable no MB46513 45120001 acceptable no MB45950 45156302 acceptable no 850.1075 Estuarine/marine

fish Fipronil 43291702 acceptabl e no

MB46136 -- -- yes 1 MB46513 -- -- yes 1 MB45950 -- -- yes 1 850.1350 Estuarine
- marine

invertebrate life cycle Fipronil 43681201 supplemental yes 6

MB46136 45259203 acceptable no MB46513 -- -- yes 1 MB45950 45259202 acceptable no 850.1400/1500 Estuarine
- marine

fish early life stage/full life cycle Fipronil 44605502 45265101 acceptable no MB46136 -- -- yes 1 MB46513 -- -- yes 1 MB45950 -- -- yes 1 850.4400/5400 Aquatic plant tier

1 Fipronil 42918658 42918656 429186 60 42918659 42918657 acceptable no

MB46136 -- -- yes 1 MB46513 43279705 acceptable yes 7 MB45950 -- -- yes 1 850.1735 Whole sediment

acute f reshwater invertebrate toxicity Fipronil 45878001 acceptable yes 8

MB46136 45175901 acceptable yes 8 MB46513 45375901 acceptable yes 8 MB45950 45084801 acceptable yes 8 850.1740 Whole sediment

acute estuarine marine invertebrate toxicity Fipronil
-- -- yes

MB46136 -- -- yes MB46513 -- -- yes MB45950 -- -- yes 850.1790 Chronic Sediment

Toxicity Fipronil
-- -- yes

MB46136 -- -- yes MB46513 -- -- yes MB45950 -- -- yes 1 - Estimated value used in previous risk assessments 2 - Non -passerine and passerine requirements will be of lesser concern met 3 -Non -passerine requireme nt met, passerine not met but available parent data suggest passerines 4 - Testing with parent pesticide should suffice to represent contributions from degradates 5 - Literature value used in place of guideline study in past risk assessments 6 - Previously waived requirement of repeated study though no NOEC established 7 - Single species tested, requirement outstanding for multiple unicellular and vascular aquatic plants 8 - single species tested ( Chironimus tentans ), current requirements include two additional species (Hyalella azteca and Leptocheirus plumulosus )

### Page 38 of 71



### The following tables present the previous risk assessment approaches for establishing e sti m ated effects endpoints for various taxonomic groups in the absence of empirical effects with the respective taxonomic group and chemical. In these tables, any established effects threshold with an origin number of “1” is derived from direct testing. All other origin codes correspond to a situation here there are no available effects data suitable for risk asses sment and where some estimation approach was used to continue with risk assessment. The Agency considers these estimation areas to be gaps in the available suite of empirical effects knowledge. The A genc y proposes to reevaluate situations where estimatio n methods were used in past risk assessment, in light of new effects data searches, and determine if the same or similar estimation assumptions will continue for the Registration Review effort or if new data are available. The Agency desire s public comment in this regard. Table 9 . Terrestrial Organism Toxicity Endpoints Used in Past Risk Assessment Chemical Acute Toxicity

Threshold Chronic Toxicity Threshold Acute

Threshold Origin Chronic

Threshold Origin Birds Fipronil LD 50 1 1.3 mg/kg
-bw

LC 50 48 mg/kg
- diet NOEC 10 mg/kg
- diet 1 1 MB46136 LD 50 19.7 mg -bw

LC 50 84mg/kg
- diet NOEC 10 mg/kg
- diet 3 1 2 MB46513 LD 50 5 mg/kg
-bw

LC 50 119.2 mg/kg
- diet NOEC 10 mg/kg
- diet 1 2 MB45950 LD 50 26.79 mg/kg
-bw

LC 50 114 mg/kg
-bw NOEC 10 mg/kg
- diet 3 1 2 Mam mals Fipronil LD 50 97 mg/kg
-bw NOEC 30 mg/kg
- diet NOEL 2.64 mg/kg
-bw 1 1 MB46136 LD 50 218 mg/kg
-bw NOEC 30 mg/kg
- diet NOEL 2.64 mg/kg
-bw 1 2 MB46513 LD 50 16 mg/kg
-bw NOEC 30 mg/kg
- diet NOEL 2.64 mg/kg
-bw 1 2 MB459 50 LD 50 83 mg/kg
-bw NOEC 30 mg/kg
- diet NOEL 2.64 mg/kg
-bw 1 2 Plants Fipronil 0.025 lb/acre (NOEC) Not applicable 1 Not applicable MB46136 0.025 lb/acre (NOEC) Not applicable 2 Not applicable MB46513 0.025 lb/acre (NOEC) Not applicable 2 Not appl icable MB45950 0.025 lb/acre (NOEC) Not applicable 2 Not applicable 1 most sensitive species tested 2 assumed to be equivalent to parent fipronil 3 estimated by multiplying available LC 50 by parent fipronil LD:LC 50 ratio Table 10 . Aquatic Organism Toxicity Endpoints Used in Past Risk Assessment Chemical Acute Toxicity

Threshold μ g/L Chronic Toxicity

Threshold μ g/L Acute Threshold Origin Chronic

Threshold Origin Freshwater Fish Fipronil 83 6.6 1 1

### Page 39 of 71 Chemical Acute Toxicity

Threshold μ g/L Chronic Toxicity

Threshold μ g/L Acute Threshold Origin Chronic

Threshold Origin MB46136 25 0.67 1 2 MB46513 20 0.59 1 2 MB45950 83 6.6 3 3 Estuarine/Marine Fish Fipronil 130 0.24 1 1 MB46136 21 0.039 4 5 MB 46513 31 0.057 4 5 MB45950 130 0.24 3 3 Freshwater Invertebrates Fipronil 0.22 0.011 1 6 MB46136 0.72 0.037 1 6 MB46513 200 10.31 1 6 MB45950 2.13 0.11 1 6 Estuarine/Marine Invertebrates Fipronil 0.14 <0.005 1 1 MB46136 0.56 <0.0026 1 1 MB46513 1 .5 0.054 1 7 MB45950 0.077 0.0046 1 1 Freshwater Plants (endpoints non - listed/listed plants) Fipronil Unicellular

140/<140 Vascular >100/100 Not applicable 1 Not applicable
MB46136 Unicellular

140/<140 Vascular >100/100 Not applicable 3 Not applicable
MB46513 Unicellular

>76/7.5 Vascular >100/100 Not applicable 3 Not applicable
MB45950 Unicellular

140/<140 Vascular >100/100 Not applicable 3 Not applicable
Estuarine/Marine Plants Fipronil >140/140 Not applicable 1 Not applicable MB46136 >140 /140 Not applicable 3 Not applicable MB46513 >76/7.5 Not applicable 1 Not applicable MB45950 >140/140 Not applicable 3 Not applicable 1 most sensitive species tested 2 most sensitive species tested acute value divided by O. mykis acute:chronic ratio of parent fipronil 3 assumed to be equivalent to parent fipronil for vascular and most sensitive plant species for unicellular 4 estimated based on estuarine/marine value for parent fipronil divided by largest freshwater fish acute parent to degradate ratio 5 estimated by dividing acute value by parent acute to chronic ratio for estuarine/marine fish 6 lowest acute value divided by parent fipronil acute:chronic ratio for D. magna 7 lowest acute value divided by parent fipronil acute:chronic ratio of A. bahia 

### A full accounting of data available at the time of the last ecological risk assessment performed in 2007 for fipronil are included in Appendix 3.

### Page 40 of 71



# VIII. References Ali, A., J.K. Nayar, and W. Gu. 1998. Toxicity of a phenylpy

razole insecticide, fipronil, to mosquito and chironomid midge larvae in the laboratory . Journal of the American Mosquito Control Association 14:216
- 218. Avery , M. L., T. M. Primus, E. M. Mihaich, D. G. Decker, and J. S. Humphrey . 1998. Consumption of fipronil
- treated rice seed does not affect captive blackbirds. Pesticide Science 52:(91
- 96). Biever, R.C., J.R. Hoberg, B. Jacobson, E. Dionne, M. Sulaaiman, and P McCahon. 2003. Icon rice seed treatment toxicity to crayfish (

Procambarus clarkii) in experimental rice paddies. Environmental Toxicology and Chemistry

22:167 - 174. Chandler, G.T., T.L. Cary, D.C. Volz, S.S. Walse, J.L . Ferry , and S.L. Klosterhaus. 20034. Fipronil effects on estuarine copepod ( Amphiascus tenuiremis ) development, fertility, and reproduction: A rapid life
- cycle assay in 96
- well microplate format. Environmental Toxicology and Chemistry

23:117 - 124. Chaton, P.F., P. Ravanel, M. Tissut, and J.C. Meyran. 2002. Toxicity and bioaccumulation of fipronil in the nontarget arthropodan fauna associated with subalpine mosquito breeding sites. Ecotoxicological and Environmental Safety 52:8 - 12. Key , P.B., K.W. Chung, A.D. Opatkiewicz, E.F. Wirth, and M.H. Fulton. 2003. Toxicity of the insecticides fipronil and endosulfan to se lected life stages of the grass shrimp (Palaemonetes pugio). Bull. Environ. Contam. Toxicol 70:533
- 540. Konwick, B.J., A.T. fisk, A.W. Garrison, J. K. Avantis, and M.C. Black. 2005. Acute enantioselective toxicity

of fipronil and its desulfinyl photoproduct to Ceriodaphnia dubia . Environmental Toxicology and Chemistry

24: 2350 - 2355. Maher, B. 2005a. The Case of the Anomalous Springs. Using all the clues to solve a karst mystery . USGS presentation to the ESIFrance - UT Karst Workshop; February 8, 20 05 Mulder, P.G., Jr. 1997. Effects of insecticides on thrips populations peanut injury growth and yi eld, 1995. in C.R. Saxena, Arthropod Management Tests, Volume 22, Entomol. Soc. Of Am., L anham, MD 22:284
- 285. Overmyer, J.P., B.N. Mason, K.L . Armbr ust. 2005. Acute toxicity of imidacloprid and fipronil to a nontarget aquatic insect, Simulium vittatum Zetterstedt cy tospecies IS - 7. Bull. Environ. Toxicol. 74:872
- 879.

### Page 41 of 71



### Peveling, R., and S.A. Demba. 2003. Toxicity and pathogenicity

of Metarhizium a nisopliae var. acridum (Deuteromycotina, H yphomycetes) and fipronil to the fringe
- toed lizard Acanthodactylus dumerili (Squamata: Lacertidae). Environ Toxicol Chem.22: 1437
- 47. Sandstrom, M.W. and J. E. Madison. 2003. Determination of Fipronil and Degrad ates in Environmental
- Water Samples by Solid
- Phase Extraction and Gas Chromatography/Mass Spectrometry (GC/MS). USGS, National Water Quality Laboratory . SETAC Meeting Poster. Schlenk, d., D.B. Huggett, J. Allgood, E. Bennett, J. Rimoldi, A.B. Beeler, D. Block, A.W. Holder, R. Hovinga, and P. Bedient. 2001. Toxicity of fipronil and its degradation products to Procambarus sp .; field and laboratory studies. Arch. Environ. Contam. Toxicol. 41: 325
- 332. Shan, Z., L. Wang, D. cali, R. Gong, Z. Zhu, and F. Yu. 2003. Impact of fipronil on crustacean aquatic organisms in a paddy field
- fishpond ecos ys tem. Bull. Environ. Contam. Toxicol. 70;746
- 752. Stark, J.D., and R.I . Vargas. 2005. Toxicity and hazard assessment of firponil to Daphnia pulex. Ecotoxico logy and Environmental Safety 62: 11 - 16. Stevens, M.M., S. Helliwell, and G.N. Warren. 1998. Fipronil seed treatments for the control of chironomid larvae (diptera:Chironomidae) in aeriall y- sown rice crops. Field crops research 57:195
- 207. Stevens, M. M., K.M. Fox , N.E. Coombes, and L .A. Lewin LA. 1999. Effect of fipronil seed treatments on the germination and earl y growth of rice, Pesticide Science 55: 517 - 523. United States Environmental protection Agency (YSEPA). 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. USEPA. (20 10 ) Screening Level Estimates of Agricultural Uses on Fipronil . Biological and Economic Assessment Division, Office of Pesticide Programs. Dated August 24, 2010. United States Geologic al Survey (USGS). 2003. Fipronil and Degradation Products in the Rice
- Producing Areas of the Mermentau River Basin, Louisiana, February
September 2 000. USGS Fact Sheet FS
- 010 - 03. Volz , D.C., E.F. Wirth, M.H. Fulton, G.I. Scott, E. Strosier, D.S. block, J.L. ferry, S.S. Walse, and G.T. chandler. 2003. Effects of fipronil and chlorpy rifos on endocrine
- related endpoints in female grass shrimp ( Palaemonetes pugio ). Bull.

### Page 42 of 71 

### Environ. Contam. Toxicol. 71:497
- 503. Wirth, E.F., P.L . Pennington, J.C. L awton, M.E. DeL orenzo, D. Bearden, B. Shaddrix, S. Siversten, and M.H.Fulton. 2004. The effect of contemporary
- use insecticide (fipronil) in an estuarine m esocosm. Environmental Pollution 131:365
- 371.

### Page 43 of 71



# Ap pendix 1 . CurrentlyRegistered Uses of Fipronil. Table 1 . Methods and rates of application of currently registered uses of fipronil. Use Site Max. Rate

p er App Max. Rate

Unit/Area *UG Form Max.# Apps cc & yr Max. App

Rate/ cc & yr Min. App

Interval (days) Application Equipment/Type

(Reg # Code) Aquatic Non - Food Industrial Drainage Systems 0.00245 lb/a B/S NS NS NS Bait application. 1713 lb/a EC NS N S NS Soil treatment (rodding and trenching). 0.0393 lb/drain EC NS NS NS Soil treatment (subslab injection). 1819 lb/a WP NS NS NS Soil treatment (rodding and trenching). 0.0418 lb/drain WP NS NS NS Soil treatment (subslab injection). Sewage Systems 0.00245 lb/a B/S NS NS NS Bait application. NDC B/S NS NS NS Bait application; Crack and crevice treatment; Spot treatment. Forestry Forest Tree Management/Forest Pest Management NDC B/S NS NS 90 d Bait application. Forest Trees (Softwoods, Conifers) 0.000556 lb/cu ft G NS NS NS Soil/media treatment. Pine (Forest/Shelterbelt) 0.131 lb/a FlC 1 / yr .131 lb / a NS Soil injection treatment. Indoor Food Dairy Farm Milk Handling Facilities/Equipment NDC B/S NS NS NS Crack and crevice treatment. Food/Grocery/Marketing/St orage/Distribution Facility Premise 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment. Household/Domestic Dwellings Indoor Food Handling Areas 0.00408 lb/a B/S NS NS NS Bait application. Indoor Medical Hospitals/Medical Institutions Premises (Human/Veterinary) 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000055 lb/placement B/S NS NS NS Bait application. 0.00000099 lb/room B/S NS NS NS Bait application.

### Page 44 of 71 Use Site Max. Rate

p er App Max. Rate

Unit/Area *UG Form Max.# Apps cc & yr Max. App

Rate/ cc & yr Min. App

Interval (days) Application Equipment/Type

(Reg # Code) NDC B/S N S NS NS Crack and crevice treatment; Spot treatment. Indoor Non - Food Bathroom Premises/Hard Surfaces 0.00000055 lb/placement B/S NS NS NS Bait application. NDC B/S NS NS NS Crack and crevice treatment; Spot treatment. Commercial Storages/Warehouses Pr emises 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000055 lb/placement B/S NS NS NS Bait application. 0.00000099 lb/room B/S NS NS NS Bait application.

NDC B/S NS NS NS Crack and crevice tre atment; Spot treatment. Commercial Transportation Facilities
Nonfeed/Nonfood 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000055 lb/placement B/S NS NS NS Bait application. 0.00000099 lb/room B/S NS NS NS Bait application.

NDC B/S NS NS NS Crack and crevice treatment; Spot treatment. Commercial/Institutional/In dustrial Premises/Equip. (Indoor) 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000055 lb/placement B/S NS NS NS Bait application. 0.00000099 lb/room B/S NS NS NS Bait application. 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment.

NDC B/S NS NS NS Bait application; Crack and crevice treatment; Spot treatment. Dairies/Cheese Processing Plant Premises (Nonfood Contact) 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment. Eating Establishments 0.00000099 lb/room B/S NS NS NS Bait application. NDC B/S NS NS NS Crack and crevice treatment. Eating Establi shments Food Handling Areas (Nonfood Contact) 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment. NDC B/S NS NS NS Crack and crevice treatment. Eating Establishments Food Serving Areas (Nonfood Contact) 0.00408319 lb/a B/S NS NS NS Bait application. 0.00001196 lb/placement B/L NS NS NS Bait application. 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment.

### Page 45 of 71 Use Site Max. Rate

p er App Max. Rate

Unit/Area *UG Form Max.# Apps cc & yr Max. App

Rate/ cc & yr Min. App

Interval (days) Application Equipment/Type

(Reg # Code) Eating Establishments Non
Food Areas (Nonfood Contact) NDC B/S NS NS NS Crack and crevice treatment. Feed Mills/Feed Processing Plants 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment. Food Processing Plant Non - Food Handling Areas 0.00000099 lb/room B/S NS NS NS Bait application. Food Processing Plant Premises (Nonfood Contact) 0.00408319 lb/a B/S NS NS NS Bait application. 0.00001196 lb/placement B/L NS NS NS Bait application.

NDC B/S NS NS NS Crack and crevice treatment. Food Stores/Markets/Supermarke ts Premises NDC B/S NS NS NS Crack and crevice treatment. Meat Processing Plant Premises (Nonfood Contact) NDC B/ S NS NS NS Crack and crevice treatment. Refuse/Solid Waste Sites (Indoor) 0.00000055 lb/placement B/S NS NS NS Bait application. NDC B/S NS NS NS Crack and crevice treatment; Spot treatment. Ships And Boats 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000099 lb/room B/S NS NS NS Bait application.
Zoos 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000055 lb/placement B/S NS NS NS Bait application. 0.00000099 lb/room B/S NS NS NS Bait application.

NDC B/S NS NS NS Crack and crevice treatment; Spot treatment. Indoor Residential Cats (Adults/Kittens) NDC L NS / a 30 d Animal treatment (rub
- on and spray). Dogs/Canines (Adults/Puppie s) 0.000904 lb/lb animal RTU NS NS 28 d Animal treatment (rub
- on and spray). NDC L NS / a 30 d Animal treatment (rub
- on and spray). Household/Domestic Dwellings Contents 0.00000099 lb/room B/S NS NS NS Bait application. Household/Domestic Dwellings Ind oor Premises 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application.

### Page 46 of 71 Use Site Max. Rate

p er App Max. Rate

Unit/Area *UG Form Max.# Apps cc & yr Max. App

Rate/ cc & yr Min. App

Interval (days) Application Equipment/Type

(Reg # Code) 0.00000055 lb/placement B/S NS NS NS Bait application. 0.00000099 lb/room B/S NS NS NS Bait application. 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment.

NDC B/S NS NS NS Bait application; Crack and crevice treatment; Spot treatment. Refuse/Solid Waste Containers (Garbage Cans) NDC B/S NS NS NS Bait application. Outdoor Residential

Household/Domestic Dwellings Outdoor Premi ses 0.005005 lb/1 gal EC 2 / yr NS NS Crack and crevice treatment; Outdoor general surface spray. 0.1305 lb/25 gal WP 2 / yr NS NS Crack and crevice treatment; Outdoor general surface spray. 0.00408319 lb/a B/S NS NS 75 d Bait application. 0.0000155 lb/linear ft EC 2 / yr NS NS Perimeter treatment. 0.00000259 lb/linear ft RTU 1 / yr NS NS Mound treatment; Perimeter treatment; Spot treatment; Spray. 0.0000163 lb/linear ft WP 2 / yr NS NS Perimeter treatment. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment.

NDC B/S NS NS NS Bait application; Crack and crevice treatment; Spot treatment. Refuse/Solid Waste Containers (Garbage Cans) NDC B/S NS NS NS Bait application. Residential L awns 0.0011271 lb/a B/S 4 / yr NS 21 d Bait application; Broadcast. 0.025 lb/a G 1 / yr .05 lb / a NS Broadcast; Subsurface/slit application treatment. NDC B/S 4 / yr NS 21 d Mound treatment.

Terrestrial Food + Feed Crop Orchards (Unspecified) NDC B/ S NS NS 90 d Bait application. Potato, White/Irish 0.0999775 lb/a FlC NS NS NS Soil in
- furrow treatment. Terrestrial Non - Food + Outdoor Residential Fencerows/Hedgerows 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment.

NDC B/S NS NS NS Bait application. Ornamental and/or Shade Trees NDC B/S NS NS NS Bait application.

### Page 47 of 71 Use Site Max. Rate

p er App Max. Rate

Unit/Area *UG Form Max.# Apps cc & yr Max. App

Rate/ cc & yr Min. App

Interval (days) Application Equipment/Type

(Reg # Code) Paths/Patios 0.00244991 lb/a B/S NS NS NS Bait application. Terrestrial Non - Food Crop Christmas Tree Plantations 0.000 556 lb/cu ft G NS NS NS Soil/media treatment. Commercial Storages/Warehouses Premises 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application.

NDC B/S NS NS NS Bait application. Commercial/Industrial Lawns 0.0 00025 lb/a B/S 4 / yr NS 21 d Broadcast. 0.025 lb/a G 1 / yr .05 lb / a NS Broadcast; Subsurface/slit application treatment. NDC B/S 4 / yr NS 21 d Mound treatment.

Commercial/Institutional/In dustrial Premises/Equipment (Outdoor) 0.00501 lb/1 gal EC 2 / yr NS NS Crack and crevice treatment; Outdoor general surface spray. 0.1305 lb/25 gal WP 2 / yr NS NS Crack and crevice treatment; Outdoor general surface spray. 0.00408 lb/a B/S NS NS NS Bait application. 0.025 lb/a G 1 / yr .05 lb / a NS Broadca st; Subsurface/slit application treatment. 0.0000155 lb/linear ft EC 2 / yr NS NS Perimeter treatment. 0.0000163 lb/linear ft WP 2 / yr NS NS Perimeter treatment. 0.0000120 lb/placement B/L NS NS NS Bait application. 0.00000002 lb/spot B/S NS NS NS Crack and crevice treatment.

NDC B/S NS NS NS Bait application; Crack and crevice treatment; Spot treatment. Corn, Field 0.0976 lb/lb seed FlC NS NS NS Seed treatment. Eating Establishments NDC B/S NS NS NS Bait application. Golf Course Turf 0.000025 lb/a B/S 4 / yr NS 21 d Broadcast. 0.025 lb/a G 1 / yr .05 lb / a NS Broadcast; Subsurface/slit application treatment. NDC B/S 4 / yr NS 21 d Mound treatment. Industrial / Construction Areas (Outdoor) 1.044 lb/100 gal WP NS NS NS Soil treatment (subs lab injection); Void treatment. 0.976 lb/98 gal EC NS NS NS Soil treatment (subslab injection); Void treatment. 64.3 lb/a EC NS NS NS Surface treatment. 68.2 lb/a WP NS NS NS Surface treatment.

### Page 48 of 71 Use Site Max. Rate

p er App Max. Rate

Unit/Area *UG Form Max.# Apps cc & yr Max. App

Rate/ cc & yr Min. App

Interval (days) Application Equipment/Type

(Reg # Code) 0.00393 lb/linear ft EC NS NS NS Soil treatment (rodding and trenching); Soil treatment (subslab injection); Void treatment. 0.00418 lb/linear ft WP NS NS NS Soil treatment (rodding and trenching); Soil treatment (subslab injection); Void treatment. Nonagricultural Outdoor Buildings/Structures NDC B/S NS N S NS Bait application; Crack and crevice treatment; Spot treatment. Nonagricultural Uncultivated Areas/Soils NDC B/S NS NS 90 d Bait application. Nursery Stock 0.0250 lb/a G 1 / yr .025025 lb / a NS Broadcast.
Ornamental and/or Shade Trees 1.04 lb/100 g al WP NS NS NS Crack and crevice treatment; Foam application; Void treatment. 0.976 lb/98 gal EC NS NS NS Crack and crevice treatment; Foam application; Void treatment. 0.0250 lb/a G NS .025025 lb / a NS Broadcast. 0.000556 lb/cu ft G NS NS NS Soil/media treatment. NDC B/S NS NS 90 d Bait application. Ornamental Herbaceous Plants 0.0250 lb/a G NS .025025 lb / a NS Broadcast. 0.000556 lb/cu ft G NS NS NS Soil/media treatment. Ornamental Lawns and Turf 0.000025 lb/a B/S 4 / yr NS 21 d Broadcast. 0.0250 lb/a G 1 / yr .05 lb / a NS Broadcast; Subsurface/slit application treatment. NDC B/S 4 / yr NS 21 d Mound treatment. Ornamental Nonflowering Plants 0.0250 lb/a G NS .025025 lb / a NS Broadcast. 0.000556 lb/cu ft G NS NS NS Soil/media treatment. Ornamental Sod Farm (Turf) 0.000025 lb/a B/S 4 / yr NS 21 d Broadcast. 0.025 lb/a G 2 / yr .05 lb / a NS Broadcast; Subsurface/slit application treatment. NDC B/S 4 / yr NS 21 d Mound treatment. Ornamental Woody Shrubs and Vines 0.0250 lb/a G NS . 025025 lb / a NS Broadcast. 0.000556 lb/cu ft G NS NS NS Soil/media treatment. NDC B/S NS NS 90 d Bait application. Paved Areas (Private Roads/Sidewalks) NDC B/S NS NS NS Bait application. Potting Soil/Topsoil 0.000556 lb/cu ft G NS NS NS Soil/media treatment.

### Page 49 of 71 Use Site Max. Rate

p er App Max. Rate

Unit/Area *UG Form Max.# Apps cc & yr Max. App

Rate/ cc & yr Min. App

Interval (days) Application Equipment/Type

(Reg # Code) Recreation Area Lawns 0.000025 lb/a B/S 4 / yr NS 21 d Broadcast. 0.025 lb/a G 1 / yr .05 lb / a NS Broadcast; Subsurface/slit application treatment. NDC B/S 4 / yr NS 21 d Mound treatment. Recreational Areas 0.025 lb/a G 1 / yr .05 lb / a NS Broadcast; Subsurface/slit application treatment. Refuse/Solid Waste Sites (Outdoor) NDC B/S NS NS NS Bait application; Crack and crevice treatment; Spot treatment. Utility Poles / Right
- Of

Way 0.00393 lb/linear ft EC NS NS NS Soil treatment (subslab injection and trenching); Other soil treatment. 0.00418 lb/linear ft WP NS NS NS Soil treatment (subslab injection and trenching); Other soil treatment. Wood Protection Treatment To Buildings/Products Outdoor 1.04 lb/100 gal WP NS NS NS Crack and crevi ce treatment; Foam application; Void treatment. 0.976 lb/98 gal EC NS NS NS Crack and crevice treatment; Foam application; Void treatment. Zoos 0.00408 lb/a B/S NS NS NS Bait application. 0.0000120 lb/placement B/L NS NS NS Bait application.

NDC B/S NS NS NS Bait application. LEGEND HEADER ABBREVIATIONS Use Site : The use site refers to the entity (crop, building, surface or article) where a pesticide is applied and/or which is being p rot ected. Max.Rate per App : Maximum dose for a single application to a single site. System calculated. Max.Rate Unit/Area : Units and Area associated with the maximum dose. *UG : Use Group codes. Form : The physical form of the end use product found in the container. Max. # Apps cc & yr : The maximum number of appli cations. Max. A pp Rate/cc & yr : The maximum amount of pesticide product that can be applied to a site in one growing season (/cc) or during the span of one year (/yr). Min. App Interval (days): The minimum retreatment interval between applications in day s (aggreg ated). Application Equipment : The equipment used to apply pesticide (aggreg ated). Application T ype : The type of pesticide application (aggreg ated). ABBREVIATIONS AN - As Needed. NA - Not Applicable. NS - Not Specified (on label).

### Page 50 of 71

(L)
- The dosage information provided is from the label in terms of product ( e.g. , ounces, gallons, or pounds of the product) because there was insufficient information ( e.g. , missing density, area, or active ingredient percentages) to provide converted dosage information. ~ - The tilde in "Max. Rate per App" indicates a dosage that includes information from a SLN label. UC - Unconverted due to lack of data (on label). APPLICATION RATE W : PPM calculated by weight V : PPM calculated by volume U : Unknown whether PPM is given by weight or by volume cw t : Hundred W eight. nnE - xx : nn times (10 power - xx), for instance, "1.234E
- 4" is equivalent to ".0001 234".

-- : No description available in LUIS unit conve rsion vocabulary.

~ : The dosage information includes a contribution from one or more (TQ, CL, BR, I) active ingredients. FORMULATION CODES B/L

– Bait Liquid B/S

– Bait Solid EC

– Em ulsifiable Concentrate FlC

– Formulation Intermediate Concentrate G

– Granular L

– Liquid RTU

– Ready
- to - use WP

– Wettable Po wd er

### Page 51 of 71



# Appendix 2 . Chemical Names, Structures, Maxim um Reported Amounts of Fipronil and its Degradates and Overview of Degradation Pathways . Table A . Chemical Names and Structures of Fipronil and its Degradates. Chemical Name Structure Fipronil (MB 46030) IUPAC name: 5 - amino
- 1 - (2,6
- dichloro
- α,α,α - trifluoro
-p - tolyl)
- 4 - trifluoromethylsulfinylpyrazole
- 3 - carbonitrile CAS name: 5 - amino
- 1 - [2,6 - dichloro
4 - (trifluoromethyl)phenyl]
- 4 - [(trifluoromethyl)sulfinyl]
- 1H pyrazole
- 3 - carbonitrile 

## N N Cl

Cl H 2 

## N S

C CF 3 

## O CF 3



## N MB 45897 CAS name: 5 - amino
- 1 - (2,6
- dichloro
alpha,alpha,alpha
- trifluoro
-p - tolyl)
- 1H -py razole
- 3 - carbonitrile 

## N N Cl

Cl H 2 

## N

C CF 3 

## N Fipronil sulfide (MB 45950) CAS name: 5 - amino
- 1 - (2,6
- dichloro
4 - (trifluoromethyl)phenyl)
- 4 - trifluoromethylthio
- 1 -py

razole
- 3 - carbonitrile 

## N N Cl

Cl H 2 

## N S

C CF 3 

## CF 3



## N Fipronil sulfone (MB 46136) CAS name: 5 - amino
- 1 - (2,6
- dichloro
a,a,a - trifluoro
-p - tolyl)
- 4 - trifluoro
methylsulfonylpyrazole
- 3 - carbonitrile 

## N N Cl

Cl H 2 

## N S

C CF 3 

## O CF 3



## N O

### Page 52 of 71

Chemical Name Structure MB 46513 CAS name: 5 - amino
- 1 - (2,6
- dichloro
alpha,alpha,alpha
- trifluoro
-p - tolyl)
- 4 - trifluoro
- methylpyrazol e - 3 - carbonitrile 

## N N Cl

Cl H 2 

## N CF 3



## C CF 3 

## N RPA 104615 CAS name: 5 - amino
- 3 - cyano - 1 - (2,6
- dichloro
- 4 - trifluoromethylphenyl) pyrazole
- 4 - sulfonic acid, potassium 

## N N Cl

Cl H 2 

## N S

C CF 3 

## O OH

N O

RPA 105048 CAS name: 1 - (2,6
- dichloro
- 4 - trifluoromethylphenyl)
- 3 - amino
- 5 - amino
- 4 - trifluoromethylsulfonylpyrazole 

## N N Cl

Cl H 2 

## N CF 3



## C CF 3 

## O H 2 

## N Fipronil amide (RPA 200766) CAS name: 5 - amino
- 1 - (2,6
- dichloro
4 - (trifluoromethyl)phenyl)
- 4 - trifluoromethylsulfonyl
- 1H -pyrazole
3 - carboxamide 

## N N Cl

Cl H 2 

## N S

C CF 3 

## O CF 3



## O H 2 

## N Table B . Maximum Reported Amounts of Fipronil Degradation Products. Degradate Maximum % of Applied (μg/L

or μg/kg in Field Studies ) Study Type MRID MB 45897 Laboratory studies

0.76 % (252 d) 1.0% (120 d) Aerobic soil metabolism Anaerobic aquatic metabolism 42918663 43291704 14.16% TRR (uptake edible) 22.92% TRR (uptake inedible) Bioaccumulation in Fish 43291707

### Page 53 of 71 Degradate Maximum % of Applied (μg/L

or μg/kg in Field Studies ) Study Type MRID 24.28% TRR (uptake whole fish) 31.97% TRR (depuration edible) 47.87% TRR (depuration inedible) 26.14% TRR (depuration whole) Fipronil sulfide (M B 45950) Laboratory studies

12.7 % (30 d , Control ) 4.88 % (336 d) 47.0 % (365 d) 82.6 % (365 d) 17% (35 d , 0 - 14 cm soil section) Soil photolysis Aerobic soil metabolism Anaerobic aquatic metabolism Aerobic aquatic metabolism Aged column leaching 42918662 42918663 43291704 44261909 42918664 9.04% TRR (uptake edible) 9.03% TRR (uptake inedible) 8.55% TRR (uptake whole fish) 15.49% TRR (depuration edible) 16.33% TRR (depuration inedible) 11.21% TRR (depuration whole) Bioaccumulation in Fish 43291707

Terrestrial field dissipation studies 66.6 μg/kg (12 m) 62.8 μg/kg (12 m) 49.9 μg/kg (8 m) 44.5 μg/kg (16 m) 18 - m CA In furrow corn 18 - m NE In furrow corn 18 - m NC In furrow

corn 18 - m W A In furrow

corn 43401103 8.3 μg/kg (after application 2) 11.5 μg/kg (183 d) 490 d CA foliar cotton 548 d WA foliar p otato 44262826 Aquatic field dissipation studies Water: 0.49 μg/L (3.9 d) Sed./Soil: 7.3 μg/kg (drain ditch) Water: 0.26 μg/L (
- 1 d) Sed./Soil: 5.9 μg/kg (drain ditch) Water: 0.15 μg/L (1 d) Sed./Soil: 4.0 μg/kg (drain ditch) Water: 0.33 μg/L (2.88 d) Sed./Soil: <0.6 μg/kg 98 d LA rice trial 1 103 d LA rice trial 2 94 d LA rice trial 3 113 d LA rice trial 4 45344701
Water: <1 μg/L Sed./Soil: 32 μg/kg (84 d) Water: <1 μg/L Sed./Soil: 7 μg/kg (55 d) Water: <1 μg/L Sed./Soil: 25 μg/kg (258 d) Water: <1 μg/L Sed./Soil: 15 μg/kg (258 d) Water: <1 μg/L Sed./Soil: 10 μg/kg (306 d) Water: <1 μg/L Sed./Soil: 13 μg/kg (127
- 252 d) 361 d MS rice seed Trt. 361 d MS rice soil Trt. 375 d TX rice seed Trt. 375 d TX rice soil Trt. 376 d CA rice seed Trt. 379 d CA rice soil Trt. 44443402

0.13 μg/L (3 d) 0.35 μg/L (1 d) 0.22 μg/L (23 d) <0.083 μg/L 0.12 μg/L (3 d) 0.15 μg/L (1 d) 118 d LA drill
- seeded rice, site 1 116 d LA dry
- seeded rice, site 1 118 d LA pre
- sprout rice, site 1 111 d LA drill
- seeded rice, sit e 2 109 d LA dry
- seeded rice, site 2 107 d LA pre
- sprout rice, site 2 46016801 Long
- term soil dissipation studies

### Page 54 of 71 Degradate Maximum % of Applied (μg/L

or μg/kg in Field Studies ) Study Type MRID 14 μg/kg (85 d, 3 y) 12 μg/kg (91 d, 3 y) 10 μg/kg (101 d, 3 y) 8 μg/kg (190 d, 3 y) 10 μg/kg (1 d, 4 y) 29 μg/kg (92 d, 2 y) 4 y NE Corn PPI 4 y IL Corn PPI 4 y OH Corn PPI 4 y MS Cotton foliar 4 y TX Cotton foliar 4 y WA Potato foliar 46477001 Fipronil sulfone (M B 46136) Laboratory studies

9.4 % (30 d, Control) 24.4 % (336 d) 0.6 % (59 d) 19 % ( 0 d , 0 - 13 cm soil section) Soil photolysis Aerobic soil metabolism Anaerobic aquatic metabolism Un - aged column leaching 42918662 42918663 43291704 42918664 54.9% TRR (uptake edible) 59.07% TRR (uptake inedible) 27.98% TRR (uptake whole fish) 47.96% TRR (depuration edible) 101.9% TRR (depuration inedible) 43.8% TRR (depuration whole) Bioaccumulation in Fish 43291707

Terrestrial field dissipation studies 7.6 μg/kg (3 m) 8.9 μg/kg (2 m) 5.4 μg/kg (2 m) 6.2 μg/kg (4 m) 4 - m FL Bare Soil 4 - m FL Turfed Soil 4 - m NC Bare Soil 4 - m NC Turfed Soil 43291705 168.2 μg/kg (12 m) 168.6 μg/kg (12 m) 119.6 μg/kg (8 m) 182.5 μg/kg (16 m) 18 - m CA In furrow corn 18 - m NE In furrow corn 18 - m NC In furrow

corn 18 - m W A In furrow

corn 43401103 50.8 μg/kg (126 d) 36.1 μg/kg (7 d) 63.1 μg/kg (548 d) 490 d CA foliar cotton 553 d TX foliar cotton 548 d WA foliar potato 44262826 Aquatic field dissipation studies Water: 0.81 μg/L (1 d) Sed./Soil: <0.6 μg/kg Water: 0.66 μg/L (1 d) Sed./Soil: <0.6 μg/kg Water: 0.86 μg/L (1 d) Sed./Soil: <0.6 μg/kg Water: 0.57 μg/L (0.5 d) Se d./Soil: 4.3 μg/kg (drain ditch) 98 d LA rice trial 1 103 d LA rice trial 2 94 d LA rice trial 3 113 d LA rice trial 4 45344701
Water: <1 μg/L Sed./Soil: 11 μg/kg (84 d) Water: 1 μg/L (29 d) Sed./Soil: 12 μg/kg (27 d) Water: <1 μg/L Sed./Soil: 14 μg/kg (39 d) Water: <1 μg/L Sed./Soil: 19 μg/kg (39 d) Water: 1 μg/L (0 d) Sed./Soil: <5 μg/kg Water: <1 μg/L Sed./Soil: 9 μg/kg (3 d) 361 d MS rice seed Trt. 361 d MS rice soil Trt. 375 d TX rice seed Trt. 375 d TX rice soil Trt. 376 d CA rice seed Trt. 379 d CA rice soil Trt. 44443402

0.41 μg/L (3 d) 2.14 μg/L (1 d) 118 d LA drill
- seeded rice, site 1 116 d LA dry
- seeded rice, site 1 46016801

### Page 55 of 71 Degradate Maximum % of Applied (μg/L

or μg/kg in Field Studies ) Study Type MRID 0.60 μg/L (0 d) 1.73 μg/L (66 d) 0.74 μg/L (3 d) 0.85 μg/L (2 d) 118 d LA pre
- sprout rice, site 1 111 d LA drill
- seeded rice, site 2 109 d LA dry
- seeded rice, site 2 107 d LA pre
- sprout rice, site 2 Long
- term soil dissipation studies 68 μg/kg (85 d, 3 y) 72 μg/kg (91 d, 3 y) 48 μg/kg (101 d, 3 y) 10 8 μg/kg ( 351 d, 2 y) 68 μg/kg ( 3 d, 4 y) 138 μg/kg (92 d, 3 y) 4 y NE Corn PPI 4 y IL Corn PPI 4 y OH Corn PPI 4 y MS Cotton foliar 4 y TX Cotton foliar 4 y WA Potato foliar 46477001
MB 46513 Laboratory studies

44.4 % (6 d) 6.9 % (30 d) 0.9% (14 d) 1.0% (59 d) 1.6% (14 d) Aqueous photolysis Soil photolysis Aerobic s oil metabolism Anaerobic aquatic metabolism Aerobic aquatic metabolism 42 9 18661 42918662 42918663 43291704 44261909 Terrestrial field dissipation studies 28.5 μg/kg (126 d) 12.9 μg/kg (3 d) 22.7 μg/kg (183 d) 490 d CA foliar cotton 553 d TX foliar cotton 548 d WA foliar potato 44262826 Aquatic field dissipation studies Water: 1.9 μg/L (2 d) Sed./Soil: <0.6 μg/kg Water: 1.3 μg/L (1 d) Sed./Soil: <0.6 μg/kg Water: 12.3μg/L (1 d) Sed./Soil: <0.6 μg/kg Water: 0.39 μg/L (2 d) Sed./Soil: <0.6 μg/kg 98 d LA rice trial 1 103 d LA rice trial 2 94 d LA rice trial 3 113 d LA rice trial 4 45344701
Water: <1 μg/L Sed./Soil: <5 μg/kg Water: <1 μg/L Sed./Soil: <5 μg/kg Water: <1 μg/L Sed./Soil: <5 μg/kg Water: <1 μg/L Sed./Soil: <5 μg/kg Water: 3 μg/L (3 d) Sed./Soil: 11 μg/kg (376 d) Water: 2 μg/L (1 d) Sed./Soil: 10 μg/kg (3 d) 361 d MS rice seed Trt. 361 d MS rice soil Trt. 375 d TX rice seed Trt. 375 d TX rice soil Trt. 376 d CA rice seed Trt. 379 d CA rice soil Trt. 44443402

0.88 μg/L (2 d) 5.38 μg/L (1 d) 3.18 μg/L (2 d) 0.20 μg/L (9 d) 7.22 μg/L (1 d) 6.16 μg/L (1 d) 118 d LA drill
- seeded rice, site 1 116 d LA dry
- seeded rice, site 1 118 d LA pre
- sprout rice, site 1 111 d LA drill
- seeded rice, site 2 109 d LA dry
- seeded rice, site 2 107 d LA pre
- sprout rice, site 2 46016801 Long
- term soil dissipation studies 3 μg/kg (3 d, 3 y) <2 μg/kg 4 y NE Corn PPI 4 y IL Corn PPI 46477001

### Page 56 of 71 Degradate Maximum % of Applied (μg/L

or μg/kg in Field Studies ) Study Type MRID 3 μg/kg (1 d, 4 y) 22 μg/kg (3 d, 1 y) 14 μg/kg (1 d, 4 y) 11 μg/kg (3 d, 3 y) 4 y OH Corn PPI 4 y MS Cotton foliar 4 y TX Cotton foliar 4 y WA Potato foliar RPA 104615 Laboratory studies

8.3 % (6 d) 7.2% (30 d) 4% (35 d , 0 - 14 cm soil section) Aqueous photolysis Soil photoly sis Aged column leaching 42 9 18661 42918662 42918664 RPA 105048 Laboratory studies

17.6 % (368 d) 7.7% (365 d) ASM of MB 46513 Aerobic aquatic metabolism 44262830 44261909 Fipronil amide (RPA 200766) Laboratory studies

54.2 % (30 d, pH 9, HPLC) 8.6 % (30 d) 38.3 % (336 d) 18.7% (365 d) 11.1% (60 d) 26% (35 d , 0 - 14 cm soil section) Hydroly sis Soil photolysis Aerobic soil metabolism Anaerobic aquatic metabolism Aerobic aquatic metabolism Aged column leaching 42977905 42918662 42918663 43291704 44261909 42918 664 Terrestrial field dissipation studies 3.7 μg/kg (3 m) 6.2 μg/kg (3 m) 4 - m FL Bare Soil 4 - m NC Bare Soil 43291705 90.1 μg/kg (4 m) 109.6 μg/kg (12 m) 40.5 μg/kg (4 m) 53.5 μg/kg (14 m) 18 - m CA In furrow corn 18 - m NE In furrow corn 18 - m NC In furro w corn 18 - m W A In furrow

corn 43401103 14.9 μg/kg (126 d) 11 μg/kg (14 d) 490 d CA foliar cotton 548 d WA foliar potato 44262826 Aquatic field dissipation studies Water: <1 μg/L Sed./Soil: <5 μg/kg Water: <1 μg/L Sed./Soil: <5 μg/kg Water: <1 μg/L Se d./Soil: 8 μg/kg (47 d) Water: <1 μg/L Sed./Soil: 16 μg/kg (39 d) Water: <1 μg/L Sed./Soil: <5 μg/kg Water: <1 μg/L Sed./Soil: <5 μg/kg 361 d MS rice seed Trt. 361 d MS rice soil Trt. 375 d TX rice seed Trt. 375 d TX rice soil Trt. 376 d CA rice seed T rt. 379 d CA rice soil Trt. 44443402



### d = days; m = months ; Trt. = treatment; TRR = total radioactive residues ; ASM = aerobic soil metabolism; PPI= pre -plant incorporated.

### Page 57 of 71



# Ap pendix 3 . Av ailable Effects data from most recent ecological risk assessment in 2007

a. Acute and Chronic Effects to Birds The following tables summarize the submitted acute and chronic toxicity data for avian wildlife. It should be noted that all studies are registrant submissions and found to be either acceptable or supplemental and therefore suitable for use in the risk assessment. The Agency

will be conducting an updated ECOTOX database search, not available at the time of this Problem Formulation document. The results of this updated database run will be used to more completely inform the available toxicity information for fipronil and degradates. Comparison of parent fipronil and degradate single oral dose endpoints for the bobwhite quail suggests that the photodegradate MB46513 may be more toxic than the parent and that the other two major environmental degradates MB46136 and MB45950 are less toxic that parent fipronil. There is no evidence that formulated products are more toxic, on an active ingredient adjusted basis, than technical fipronil. On first inspection the av ailable acute oral dose data may suggest that fipronil is more toxic in gallinaceous birds (pheasants, quail grouse, etc.) than in other orders. However, the number of tested species within each order is very small (3 or less), precluding any definitive c onclusion regarding any phyl ogenic relationship on sensitivity in birds. The Agency is interested in receiving public comment associated with any additional evidence that supports or refutes a hyp othesis that galliformes are uniquel y sensitive to fipronil in comparison to other birds. Acute Oral Dose Toxicity Data for Birds

Species Chemical %A.I. LD 50 mg/kg - bw MRID Northern bobwhite fipronil 96 11.3 42918617 Mallard fipronil 96.8 >2150 42918616 Pigeon fipronil 97.7 >500 42918613 Red
- legged partridge fipronil 95.4 34 42918614 Pheasant fipronil 95.4 31 42918615 House sparrow fipronil 96.7 1000 42918618 Northern bobwhite MB46513 99.7 5 43776601 Mallard duck MB46513 98.6 420 43776602 Northern bobwhite fipronil (1.6 WG) 1.6 1065 42918619

### Page 58 of 71

Dietary Acute Toxicity Data for Birds

Species Chemical %A.I. LC 50 mg/kg - diet MRID Northern bobwhite fipronil 95 48 42918620 Mallard duck fipronil 95 >5000 42918621 Northern bobwhite MB46513 97.8 119.2 45259201 Northern bobwhite MB46513 97.8 <178 44920701 Northern bobwhite MB46136 99.7 84 44890301 Northern bobwhite MB45950 98.8 114 44890302 Reproduction Toxicity Data for Birds Species Chemical %A.I. LOEC mg/kg - diet NOEC

mg/kg - diet MRID Northern bobwhite fip ronil 96.7 >10 10 42918622 Mallard duck fipronil 96.7 >1000 1000 42918623 

### A search of the ECOTOX database identified additional data for fipronil administered via the diet to male red
- winged blackbirds ( Agelaius phoeniceus L) male and female brown
headed cowbirds (

Molothrus ater Boddaert), and female boat
- tailed grackles (Q uiscalus major Viellot) (Avery

et al. 1998). Fipronil was added to a rice seed medium at 0, 325, and 500 mg a.i./kg. Birds were allowed to feed at will from open cups of the treated diet. No adverse toxicological effects were noted and no reduction in food consumption (p>0.05) was noted for any species and any

dose group. Calculation of Acute LD 50 

### or Acute LC 50 

### Ratios and Other Extrapolation Factors for Terrestrial Organisms From the data above it is evident that acute single oral dose studies are not available for MB45950 and MB46136. For the purposes of evaluating risks for these degradates, estimates for single oral dose LD 50 

### values are necessary . EFED evaluated the relati onship of the acute effects data (LD 50 

### :L C 50 

### ) for bobwhite quail, the most sensitive species tested (LD 50 

### :L C 50 

### ). The ratio of LD 50 

### to LC 50 

### from these data is 0.235 (11.3/48). This value will be used to estimate LD 50 

### values for MB45950 and MB46136, using the following equation L C 50 

### *0.235=Estimated LD 50 

### .

### Page 59 of 71 

### b. Acute and Chronic Effects to Mammals The following table presents the available mammalian toxicity data for fipronil for acute oral dose and for reproduction endpoints. The Agency will be conducting an up dated ECOTOX database search, not available at the time of this Problem Formulation document. The results of this updated database run will be used to more completely inform the available toxicity information for fipronil and degradates Toxicity Data for Mam mals Species % AI LD 50 (m g/kg - bw) MRID

Rat 93% LD 50 (mg/kg
-bw) 97 reproduction NOEC 30 mg/kg
- diet effects: litter size

and number of matings reproduction NOEL 2.64 mg/kg
-bw 42918628 42918647 Rat MB45950 LD 50 (mg/kg
-bw) 83 HED memo* Rat MB46513 LD 50 (mg/kg
-bw) 16 43235402 Rat MB46136 (98%) LD 50 (mg/kg
-bw) 218 42918675 Rat 1.6(form.)

EXP60655A LD 50 (mg/kg
-bw)>5000 42918636 Rat 0.25(form.)

RM1601c LD 50 (mg/kg
-bw)>5000 43121104 *Fipronil
- Review of toxicity studies (28
- day studies with fipro nil and metabolite RPA 200766, a developmental neurotoxicity study with fipronil and a paper on the toxicological significance of fipronil and its metabolites). From V.A. Dobozy (Registration Branch 1/HED) to M. Johnson (RD), 8/6/1997.



### c. Other Terrestrial Vertebrate Effects Fipronil was administered by gavage or by

contaminated diet in a single exposure event at 30 mg ai/kg body weight to fringe
- toed lizard s Acanthodactylus dumerili (Peveling and Demba 2003). By

four weeks post treatment, 62.5% of the liz ards feed treated diet and 42% of gavaged lizards died. In both tests survivors showed reduced feeding activity , food consumption, body

weight, and liver or fat to body weight ratios. It is notable that these values suggest an LD 50 

### on the order of 30 mg/kg
- bw which is bracketed by available LD 50 

### values for birds.

d. Terrestrial Invertebrate Effects The registrant submitted an extended laboratory contact toxicity

test to evaluate the toxicity of fipronil residues on foliage to honey bees (MRID 44884101). Ho ney bees were exposed to bean cuttings treated with 25 g of fipronil 80wg for 72 hours. By 72 hours, mortality in treatments was 100% compared to 5 to 8.35 in controls. This study was found to be supplemental.

e. Terrestrial Plant Effects Continuous seedling exposure to fipronil (up to 25 days) at 4000 mg/L did not affect rice ( Oryza sativa ) seedling growth, but that 4
- day exposure to 200 mg/L did produce

### Page 60 of 71



### reductions in seed germination (Stevens et al. 1999). Other data from the literature showed fipronil having no effect on biomass of peanuts ( Arachis hypogaea ) treated with fipronil at a rate of 0.025 lb/acre (Mulder 1997). This later study expresses effects information in units consisted with terrestrial plant exposure modeling and could as the basis for t errestrial plant risk assessment.

f. Acute and Chronic Aquatic Organism Effects The following section presents the following tables the available aquatic organism effects data for fipronil, formulated products and degradates for freshwater and estuarine/ma rine invertebrates and fish and well as aquatic plants. The data include studies originating as registrant submitted studies in compliance with 40 CFR Section 158 (identifiable as studies with MRID reference numbers). In addition effects data identified from the publicly available literature (ECOTOX database studies identifiable as studies with Author citations) are also included as captured in the 2007 ECOTOX database search. All MRID - based data have been described in previous risk assessments and those appearing in the following tables meet either the Agency acceptable or supplemental criteria. Studies identified from the ECOTOX summary of available literature have been evaluated b y the Office of Research and Development as suitable for ECOTOX inclusion and have undergone EFED evaluation for inclusion in the risk assessment for possible quantitative evaluation. The following are short summaries of studies extracted from the ECOTOX search of available literature. The Agency will be conducting an update d ECOTOX database search, not available at the time of this Problem Formulation document. The results of this updated database run will be used to more completely inform the available toxicity information for fipronil and degradates. Analy tical grade fip ronil, (>98% purity) was tested for acute toxicity using 5 th 

### instar black fl y larvae (Simulium vittatum ), a native emergent aquatic insect species of the United States (Overmye r et al. 2005). Six concentrations of fipronil, a solvent control (equivalent to highest solvent in all fipronil treatments), and a test water control were included. Test concentrations of fipronil were measured at the start and termination of the 48 - hour exposure period. The study was conducted three times with one replicate at each control and test concentration. Medial lethal concentrations and corresponding probit slope estimates were reported: test 1 L C 50 

### 0.19 μg/L slope 2.25; test 2 L C 50 

### 0.19 μg/L slope 2.43; test 3 0.29 μg/L slope 1.21. The geometric mean of these values is L C 50 

### 0.22 μg/L with a slope of 2.20. Fipronil (99.9% purity) toxicity was tested in six aquatic invertebrate species (Chaton et al. 2002 ). Studies were preformed in triplicate with 20 individuals per replicate. Controls were performed in test water, which was de
- chlorinated tap water. The following results were reported in nominal concentration units:

### Page 61 of 71

Summary of Chaton et al. (2002 ) st udy.

Species 48 - h LC 50 μg/L Probit Slope Cladocerans Daphnia pulex > highest dose Copepods Acanthocyclops robustus 84.8 4.8 Diaptomus castor 3.4 4.7 Ostracods Eucrypris virens >highest dose Dipterans Chaoborus crystallinus 646 1.5 Chironomus annularis 2.4 1.2 

### Fipronil (97.1% purity) was tested in 4 th 

### instar larvae of 6 species of mosquitoes and two species of field collected chironomid midges (Ali et al. 1998). The assay s involved 20 larvae in each of three replicates for six or seven test concentrations of fipronil . Tap water served as a diluent and control. The results in nominal units were reported as follows: Summary of Ali et al. (1998 ) study.

Species 48 - h LC 50 μg/L Probit Slope Mosquitoes Aedes aegypti 1.54 4.28 Aedes albopictus 23 1.95 Aedes taeniorhynchus 0.43 4.19 Anopheles quadrimaculatus 0.43 2.51 Culex nigripalpus 0.87 3.16 Culex quinqefasciatus 7.3 5.46 Midges Chironomus crassicaudatus 0.42 2 Gl yptendipes paripes 0.42 2.18 

### Konwick et al. (2005) evaluated the acute enantioselective toxicity of fipronil and its desulfinyl photoproduct (MB46513) to the cladoceran Ceriodaphnia dubia . Neonates of less than 24 hours age were introduced b y pipet to 3 0 mLpol yprop yl ene cups containing moderatel y hard water (control), a 0.1 % acetone solution in moderately hard water (vehicle control), or fipronil compound dissolved in acetone and diluted with moderatel y hard water. No feeding took place over the cours e of the study . Two series of tests were conducted for each fipronil enantiomer and for the racemic mixture. The first test series occurred under a normal photoperiod (16:8 light:dark fluorescent light source). The other test series was conducted dark co nditions. For the desulfinyl product, only a 16:8 photoperiod test was conducted. Three replicate tests were conducted for each compound under each photoperiod (except as noted for desulfinyl product). A total of 15 neonates (3 cups of 5) were exposed at all controls and test chemical exposure levels. Mortality was assessed b y response to a probe. At 48 hours test conditions (dissolved oxygen and pH) were measured with results ranging from 7.80
- 8.38 mg/L and 8.3
- 8.46, respectivel y. Control survival ac ceptability criteria was set and attained at >90%. All LC 50 

### values are reported on the basis of measured water concentrations of test chemical ( i.e. , adjust of nominal by

observed nominal
- measured relationship for low and high doses). The following 48
- h LC 50 

### results were reported:

### Page 62 of 71

Summary of Konwick et al. (2005) study. Ceriodaphnia dubia Mean 48 - h LC 50 (μg/L) Test compound Light Dark fipronil (+) enantiomere 11.3 +2.0 9.4 + 0.7 fipronil (
- ) enantiomere 35.4 +2.6 28.4 +2.4 fipronil racemic 17.9 +2.7 17.5 + 1.3 desulfinyl product (MB46513) 355 + 9.3 

### The toxicity

of fipronil to three aquatic invertebrates (giant river prawn ( Macrobrachium rosenbergii) , oriental river shrimp ( Macrobrachium nipponensis) , and Chinese mitten crab ( Eriocheir sinensis )) was determined under semi
- static conditions (Shan et al. 2003). Test water consisted of aerated tap water (pH 7.1) and test temperature was 20 + 1 C. Test chambers consisted of 25 l glass containers filled with 20 L of test solution. Fipronil material consi sted of a 5% suspension provided by Aventis CropScience (no other information on the content of the suspension was provided). A total of 10 test organisms were added to each test container with average loading ranging from 0.5 to 1.15 g organism/L . Test solution was replaced every 24 hours. Mortality

and any observations of abnormal behavior were recorded each 24 hours. All L C 50 

### s were reported as nominal concentrations: Summary of the Shan et al. (2003) study. Acute LC 50 (μg/L)

Species 24 h 48h 72h 96h Macrobrachium rosenbergii 6.41 2.24 1.63 0.98 Macrobrachium nipponense >25.7 11.61 7.02 4.32 Eriocheir sinensis 57.83 22.57 12.44 8.56 

### Stark and Vargas (2005) evaluated the acute toxicity of fipronil to Daphnia pulex . Regent 4Sc formulation of fipronil was serially diluted in reconstituted dilution water. Batches of 5 neonates (3 rd 

### filial generation <24 hours of age) were introduced to 30 mL plastic cups containing 25 mLof each of five to eight logarithmicall y space d fipronil concentrations and a water only control. Test conditions were static non renewal. Mortality of test subjects was evaluated based on movement under mechanical stimulation. The experiment was conducted three times with three different generations of test animals. The LC 50 

### was expressed as nominal fipronil active ingredient and reported as 15.6 μg/L (95% CI0.88 - 83) with a slope of 0.93 ( + 0.26). The toxicity

of fipronil to the crayfish Procambarus clarkii was evaluated using static renewal (4 8 h interval) methods (Biever et al. 2003). Testing was conducted with the formulation I CON 6.2 FS diluted in well water (pH 6.9, hardness 38 mg/L as CaCO 3 

### ). Test concentrations were performed in duplicate and each chamber consisted of 21 L aquaria fille d with 15 Lof test solution maintained at 22 + 1 C. Crayfish were observed every 24 hours for mortality . The fipronil nominal 96
- hr L C 50 

### was reported as 180 μg/L. Fipronil as Rhone
- Poulenc “suspensible” concentrate EXP 60145A (200g ai/L) was tested for acute toxicity

in the final larval instar of the midge Chironomus tepperi . Ten larvae were added to 25 ml glass specimen tubes containing 20 mL of fipronil so lution or

### Page 63 of 71



### untreated controls. Photoperiod was maintained at 15:9 (light:dark). The bioassays were run in triplicate and replicated 4 times with different larvae cultures all under static conditions. Mortality

was assessed as response to manipulation by forceps. The mean 24 - hr L C 50 

### was reported by the authors to be 0.43 μg/L (95% limits 0.39
- 0.47) with a mean slope of 3.29 + 0.44. Field collected grass shrimp, Palaemonetes pugio , were evaluated for acute toxic response to fipronil (Stevens et al. 1998). One study involved the use of 10 adult shrimp housed in 4 Lglass j ars filled with 2 Lof test media or control. There were two replicates per treatment. A second study involved the use of 10 larvae (one to two days old) per 600 ml beaker filled with 400 ml of media, three replicates per treatment. A third study

involv ed the use of embryos in 24
- well microtiter plates, one stage IV embryo/ 2 mL well. The control and each test concentration were allocated to a single plate for a total of 24 organisms per treatment. Pesticide grade acetone (0.1%) was used as a carrier s olvent in all treatments and controls. The following 96
- hr LC 50 

### values were reported: Summary of the Stevens et al. (1998) study. Life Stage 96 - hr LC 50 (μg/l) Palaemonetes pugio Adult 0.32 larvae 0.68 em bryo >512 

### A 96 - hr acute toxicity

study with th e adult copepod Amphiascus tenuiremis was conducted using 98% fipronil (Chandler 2004). Adult male and female organisms were exposed to four nominal concentrations of fipronil (4.3, 7.2, 12.0, and 20 μg/L) and an acetone control in artificial seawater. F our replicates per treatment level were emplo yed and the test chambers consisted of 50 mLglass cry stallizing dishes filled with 30 mLof test solution. Twenty

organisms (evenl y distributed between males and females) were introduced to each replicate, which were then incubated at 20 C for 96 hours in a 12:12 light:dark photoperiod. The L C 50 

### for combined sexes was 6.8 μg/L, with a male L C 50 

### of 3.5 μg/L and a female LC 50 

### of 13.0 μg/L. Chandler et al. (2004) conducted a life cycle study (21 day s) with the estuarine copepod A. tenuiremis exposed to fipronil (98% technical) at measured concentrations of 0.16, 0.22, and 0.4 2 μg/L in seawater. The study was conducted in 96
- well microtiter plates. One hundred forty- four test microwells for each treatment and or control were distributed over three microplates per treatment or control. One animal per treatment well was introd uced to a treatment or control solution volume of approximately 200 μL for portions of the experiment involving observed copepod rearing (endpoints specific to copepod survival and development). Alternating rows were evaluated for sexually mature copepod pairing and mating and involved two animals (male and female) per cell. The animals were fed with 2 μL of mixed algal cell suspension. All plates were maintained covered at 25C with a photoperiod of 12:12 light:dark. Treatment or control solution was renewed every 3 day s and food was introduced every 6 day s. There were no adverse effects on copepod survival observed at either day 12 or day

21 of the study (NOEC for survival 0.42 μg/L). Copepod development from stage 1 to adult was

### Page 64 of 71



### significantl y (p<0.01 ) delayed for treatment groups 0.22 and 0.42 μg/L (NOEC for delayed development 0.16 μg/L, LOEC 0.22 μg/L). Developmental delay s were observed to range from 1.5 to 2.4 day s at the LOEC of 0.22 μg/L. The number of mature adults at day

12 was also reduced at 0.22 μg/l , with controls averaging 97.8 adults and 0.22 μg/l averaging 85.6 adults. Fipronil significantly reduced (p<0.010 the incidence of female egg production at the 0.22 and 0.42 μg/L by 71% and 94% , respectively (NOEC for incidence of female egg production 0.16 μg/L LOEC 0.22 μg/L). The most sensitive endpoint from this study

was time from mating to female egg extrusion. Reproductivel y successful females took statistically longer than controls to extrude eggs at 0.16 and 0.22 μg/L (p<00.05) than controls by average margins of 1.9 and 2.3 day s, respectively (NOEC for time to egg production <0.16 μg/L, LOEC o.16 μg/L). Volz et al. (2003) examined the response of grass shrimp Palaemonetes pugio exposed to nominal concentrations of fipronil (techni cal 98%) at 0, 0.1 and 0.2 μg/L in seawater. Test chambers consisted of 70 Laquaria p[retreated for three weeks with test solutions. A total of 34 adult shrimp (17 male and 167 female) were assigned to each control and treatment chamber (three replicate chambers per treatment level). Measured concentrations of fipronil averaged 0.0979 μg/L (SD 0.02084) and 0.14298 μg/L (SD 0.04052) for the 0.1 and 0.2 μg/L treatment groups. Fipronil significantly (p=0.01) reduced adult survival at 0.14298 μg/L, with an observed 19.6% decrease relative to controls (survival NOEC 0.0979 μg/l, LOEC 0.14298 μg/l ). Among surviving shrimp, no significant (p 0.05) effects on the numbers of gravid females, female grass shrimp egg production, vitellogenin, cholesterol, and ecdysteroids were observed at any treatment level (NOEC 0.14298 μg/L). Aquatic Animal Acute Toxicity data Species Chemical %A.I. LC 50 or EC 50 μ g/L MRID or Reference Freshwater Acute Invertebrate Toxicity Data Daphnia magna Fipronil 100 190 42918625 Cerioda phnia dubia 98 (racemic) 17.9 (light condition) 17.5 (dark condition0 Konwick et al. 2005 Ceriodaphnia dubia 98.1 (
- ) enantiomere 35.4 (light

condition) 28.4 (dark condition) Konwick et al. 2005 Ceriodaphnia dubia 97.3 (+) enantiomer 11.3 (light

condition) 9.4 (dark condition) Konwick et al. 2005 Corbicula fluminea 95 >2000 46329904 Lumbriculus variegatus 99.7 >1900 46329903 Simulium vittatum >98 0.22 Overmyer et al. 2005 Acanthocyclops robustus 99.9 84.8 Chaton et al. 2002 Diaptomus castor 99.9 3.4 Chaton et al. 2002 Chaoborus crystallinus 99.9 646 Chaton et al. 2002

### Page 65 of 71

Species Chemical %A.I. LC 50 or EC 50 μ g/L MRID or Reference Giant river praw

n Macrobrachium rosenbergii 5 24h
- 6.41 48h
- 2.24 72h
- 1.63 96h
- 0.98 Shan et al. 2003 Oriental river shrimp M acrobrachium nipponense 5 24h
- >25.70 48h
- 11.61 72h
- 7.02 96h
- 4.32 Shan et al. 2003
Chinese mitten crab Eriocheir sinensis 5 24h
- >57.83 48h
- 22.57 72h
- 12.44 96h
- 8.56 Shan et al. 2003
Procambarus clarkii
-- 14.3 (96
- h) Schlenk et al. 2001 Procambarus zonangulus -- 19.5 (96
- h) Schlenk et al. 2001 Chironomus annularis 99.9 2.4 Chaton et al. 2002 Chironomus crassicaudatus 97.1 0.42 Ali et al. 1998 Glyptendipes paripes 97.1 0.42 Ali et al. 1998 Chironomus tentans 98.3 0.41 45878001 (Water
-based endpoint) Hexagenia sp. 99. 7 0.44 46329902 Aedes aegypti 97.1 1.54 Ali et al. 1998 Aedes albopictus 97.1 23 Ali et al. 1998 Aedes taeniorhynchus 97.1 0.43 Ali et al. 1998 Anopheles quadrimaculatus 97.1 0.43 Ali et al. 1998 Culex nigripalpus 97.1 0.87 Ali et al. 1998 Culex quinqefasciatus 97.1 7.3 Ali et al. 1998 Culex quinqefasciatus -- 350 Ali et al. 1999 Daphnia magna RPA 10461 94.7 100,000 43291719 Chironomus riparius RPA 200766 99.8 430 46376701 Daphnia magna MB46136 100 29 42918671 Chironomus tentans 99.1 0. 72 45175901 (Water
-based endpoint) Daphnia magna MB45950 100 100 42918669 Chironomus tentans 99.5 2.13 45084801 (Water
-based endpoint) Ceriodaphnia dubia MB46513 97.8 355 Konwick et al. 2005 Chironomus tentans 99.1 200 45375901 (Water
-based endpo int) Procambarus clarkii ICON 6.2 FS 56.02 174 45029601 Procambarus clarkii ICON 6.2 FS -- 180 Biever et al. 2003 Daphnia pulex Regent 4SC -- 15.6 Stark and Vargas 2005 Chironomus tepperi RP EXP 60145a 20% (adjusted) 0.43 (24 hr study) Stevens et al. 1 998 Freshwater Acute Fish Toxicity Data Onchorynchus mykis Fipronil 100 246 42977902 Lepomis 100 83 42918624

### Page 66 of 71

Species Chemical %A.I. LC 50 or EC 50 μ g/L MRID or Reference macrochirus Ictalurus punctatus 97 560 44299401 Onchorynchus mykis MB46136 99.2 39 42918673 Lepomis macrochirus 99.2 25 42918674 Lepomis macrochirus MB46513 No data 20 43279702 Onchorynchus mykis 94.7 >100,000 43291718 Onchorynchus mykis 100 >100,000 43279703 Onchorynchus mykis RPA104615 94.7 94.7 >100,000 43291718 Estuarine/Marine Acute Invert ebrate Toxicity Data Amphiascus tenuiremis Fipronil 98 (96 hr study) 6.8 combined 3.5 male 13.0 female Chandler et al. 2004 Palaemonetes pugio
-- adult 0.32 larvae 0.68 em bryo >512 Key

et al. 2003 Crassostrea virginianus 96.1 770 43291701 Americamys is bahia 96.1 0.14 43279701 Americamysis bahia MB46513 97.8 1.5 45120001 Americamysis bahia MB46136 99.7 0.56 45156301 Americamysis bahia MB45950 99.7 0.077 45156302 Estuarine/Marine Acute Fish Toxicity Data Cyprinodon variegatus Fipronil 96.1 130 43 291702 Aquatic Animal Chronic Toxicity data Species Chemical %A.I. LOEC/ NOEC μ g/L MRID or Reference Freshwater Invertebrate Chronic Toxicity Data Daphnia magna Fipronil 100 20/9.8 42918626 Daphnia magna MB46513 -- 100/41 43279704, 44812801 Freshwater Fish Chronic Toxicity Data Oncorynchus mykis Fipronil 96.7 15/6.6 42818627 E stuarine/Marine Invertebrate Chronic Toxicity Data Americamysis bahia Fipronil 97.7 0.005/not determined 43681201 Palaemonetes pugio 98 adult survival 0.14298/0.0979 reproduction >0.14298/0.14298 Volz et al. 2003 Amphiascus tenuiremis 98 Survival 0.22 /0.16 Time to adult 0.22/0.16 Incident of female egg production Chandler et al. 2004

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Species Chemical %A.I. LOEC/ NOEC μ g/L MRID or Reference 0.22/0.16 Time from mating to egg production 0.16/<0.16 Americamysis bahia MB45950 99.5 0.0087/0.0046 45259202 Americamysis bahia MB46136 99 0.0026 /< 0.0026 45259203 E stuarine/Marine Fish Chronic Toxicity Data Cyprinodon variegatus Fipronil 95 97 full life cycle

1.7/0.85 early life stage 0.41/0.24 45265101

44605502 Aquatic Plant Toxicity data Species Tested Chemical % A.I. 5 Day EC 50 (μg/L) NOEC

(μg/L) MRID or Refe rence Navicula pelliculosa (FW diatom) fipronil 96.1 >120 120 42918658 Lemna gibba (Duckweed) 96.1 >100 100 42918656 Selenastrum capricornutum (FW green alga) 96.1 140 <140 42918660 Skeletonema costatum (marine diatom) 96.1 >140 140 42918659 Anabaena flos aquae (FW Blue
- green alga) 96.1 >170 140 42918657 Selenastrum capricornutum (FW green alga) MB46513 98.6 76 7.5 43279705



### g. Effects on Infaunal Sediment organisms The following table presents the results of sediment toxicity testing with fipronil and degradates. Sediment Organism Toxicity Data Species Tested Chemical % A.I. 10 Day LC 50/EC 50 (NOEC) μg/kg - sediment 10 Day LC 50/EC 50 (NOEC) μg/l pore water MRID
Chironomus tentans fipronil 98.3 mo rtality 30.7(16) mo rtality 0.41(0.24) 458780 01

MB46513 97.8 - 99.6 mo rtality 1300(200) grow th 520(<200) Not available

Not available 45375901 MB46136 99.01 mo rtality 44.8(14) grow th 34.8(9.1) mo rtality 0.72(0.35)

grow th 0.41(0.41) 45175901 MB45950 99.5 mo rtality 116.9(29) grow th 50.9(54) mo rtality 2.13(0.35)

grow th 0.66 (0.94) 45084801

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### h. Calculation of Acute to Chronic Ratios and Other Aquatic Organism Extrapolations Chronic toxicity

data are available for but a subset of the freshwater invertebrate species tested in acute toxicity

studies. In o rder to capture the potential for interspecies differences in sensitivity

observed in the acute studies, an assumption was made that such differences are conserved in chronic effects. The following acute:chronic ratios (ACRs) for fipronil are available from the data set: A cute:chronic ratios (ACRs) for fipronil . Species Invertebrate or

Fish Freshwater or

Estuarine/marine Acute LC 50 Chronic NOEC ACR D. magna invertebrate freshwater 190 9.8 19.39 O. mykis fish freshwater 246 6.6 37.27 A. bahia invertebrate estuarine/marine 0.14 <0.005 >28.00 P. Pugio invertebrate estuarine/marine 0.32 0.0979 3.26 A. tenurans invertebrate estuarine/marine 6.8 <0.16 >42.50 C. variegates fish estuarine/marine 130 0.85 0.24 <152.9

<541.7 

### For the purposes of extrapolatin g acute freshwater invertebrate results to an estimated chronic effects NOEC when chronic data are unavailable, this risk assessment may use the single ACR for D. magna (19.39), where the resulting chronic NOEC estimate will be made using the calculation: LC 50

### /ACR=NOEC est 

### . For estuarine/marine invertebrates, extrapolations of acute to chronic effects endpoints would employ the ACR for A. bahia, where the resulting chronic NOEC estimate will be made using the calculation: LC 50

### /ACR=NOEC est 

### . The selection of A. bahia is made because most acute testing available for degradates uses the same species and such extrapolations within the species have the least uncertainty. There are data gaps for the degradates of concern for estuarine/marine fish. To address the se gaps this risk assessment may assume the relationship between freshwater species sensitivities for parent fipronil and degradates are conserved. The following relationships can be calculated with available data Relationship between freshwater species sensitivities for parent fipronil and degradates. Species Fipronil LC 50 Degradate LC 50 Ratio Parent to Degradate MB46136 O. mykis 246 39 6.3 L. macrochirus 83 25 3.3 MB46513 O. mykis 246 >10,000 <.00246 L. macrochirus 83 20 4.15



### i. Mesocosm, Microsom , and Field Studies Wirth et al. (2004) evaluated the effects of fipronil (purity not stated) upon estuarine mesocosms. Each mesocosm chamber consisted of an aerated tank with a simulated

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### diurnal tidal volume 55l to 250 L . Each tank consisted of 2 plots of low marsh, 2 plots of mid marsh, and a simulated stream. Natural seawater and unspecified sediment were used. Three replicate mesocosm chambers were used for a control, and 0.150, 0.355, and 5.00 μg/L nominal additions of fipronil. Dosing occurred in the seawater sump approximately

one hour prior to flood tide, avoiding a plume event. Test organisms were acclimated in the mesocosms three days prior to dosing. The community consisted of 24 6 month grass shrimp (

P. pugio, 16 males 8 females ), 30 o ys ters ( C. virginica ), 30 juvenile clams (

Mercenaria mercenaria ), and 25 fish ( C. variegatus ). Exposure duration was for 28 days, evaporative loss in each chamber was offset through deionized water additio n. Clams exhibited no adverse effects at all exposure levels. There were no significant (p=0.33) effects on oyster survival or oy ster weight (p=0.38), but height of oysters was slightl y reduced (p=0.01) at the highest dose tested. Grass shrimp exhibited reduced survival (p<0.05) at the middle dose. Grass shrimp also exhibited a dose dependent reduction in number off oviparous females, though without statistical significance. Fish exhibited no significant effects on survival, length or weight. Because concentrations of fipronil in the water column decreased substantiall y over the course of the study the NOEC and LOEC for this study can be expressed both as nominal concentration (NOEC 0.150 μg/L, LOEC 0.355 μg/L) and as a 28
- day average measured concentration (NOEC 0.076 μg/L, LOEC 0.148 μg/L). No monitoring of sediments nor for degradates was conducted in the study . Consequently the disappearance of fipronil parent from the water column cannot be reliabl y attributed to any particular fate or dissipation process. Shan et al. (2003) explored the potential effects of fipronil in rice paddy drainage water upon freshwater crustaceans. An experimental rice paddy was treated with fipronil (5% f ipronil suspension) by

spray application of 45 g ai./hectare. Water drawn from the experimental paddy

was introduced to a fishpond (concrete lined with mud and planted with “water grass”) that contained 80 M. rosenbergii , 50 M. nipponensis , and 80 E. simensis . At 24 hours post fipronil application to the paddy draw water from the paddy was introduced to the pond in a 50% volumetric mixture with existing pond water. E. simensis, immediately

after application of paddy water, showed signs of intoxication (c onvulsion and arched bodies). Within 10 days there was complete mortality of this species as compared to 50% mortality in an untreated control pond. The other test species also exhibited signs of agitation and complete mortality by 7 day s ( M. nipponensis ) or 3 day s (

M. rosenbergii) compared to controls where mortality was 345 and 13.85, respectivel y. Fipronil concentration in the fish ponds, upon application of treated paddy water was a measured 3.48 μg/L and declined to 2.6 μg/L 30 days later. Traces o f MB046136 were detected, while the other two degradates were negligible. Baye r Crop Science submitted to the Agency an evaluation of fipronil effects on the fauna of outdoor simulated ponds (MRID46733901). Fipronil, as Chipco TopChoice, was used in th e experiment. Eight outdoor ponds were used in the study (four replicates for treatment and control). Fipronil was introduced to pond surface water at a nominal initial concentration of 0.4 μg/L. The time
- weighted average concentration of fipronil in treated mesocosms from initiation of biological exposure out to 84 day s (holding non
detects at half detection limit) was 0.042 μg/L. Biological sampling commenced two

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### weeks prior to test substance treatment and continued for approximately 12 weeks after application. There were no statistically significant (P>0.05) differences in phy toplankton (determined b y phaeophytin, chlorophyll, and total pigment analysis) between control and treatment. M ean arthropod abundance was lower in the treatment than control at day 7 (52% of control), and Day 14 (61% of control) This trend reversed for days 21, 28, 42, and 56, where treatments showed increases in abundance relative to controls ranging from 0.5% to 183 %. None of the overall arthropod effects, though marked were statistically

significant (P>0.05). Within the arthropods, certain copepod species (Mesocyclops edax and Tropocyclops prasinus ) showed statistically significant (p < 0.05) reductions in a

bundance in treatment relative to control. Treatment abundances ranged from 65 to 365 of control values. By day 21 (the last day

of analysis at species resolution) these reductions were not statisticall y significant, but were still markedl y reduced 14% to 60% of controls. Hester
- Dendy sampling results for clitellora (worms and leeches) showed statistically significant increase in treatments relative to control for sampling days 8, and 14, and 56 (increases greater than 200%). Gastropods (snails) showed similar increases in abundance, though not statistically significant, in treatments relative to control. Evaluation of total macroinvertebrate insect abundance showed mixed results as the study

progressed. Reductions in total abundance were statistically significant (P<0.5) for fipronil treatment at day 8, with reductions still evident at day 28 and 56, though not statistically significant. Benthic sampling for mayfl y juveniles showed significant reductions in the presence of fipronil (p<0.05) at days 8, 14, 28, and 56 of the study . Juvenile chironomids were also reduced significantl y (p<0.05) by fipronil at day

8, though these effects were largel y reversed b y day 56 of the study . Numbers of emergent insects were too small in the study to make definitive statistically supported statements about individual taxonomic groups. However, total emergent insects were lower in the fipronil treatment than in control for all sampling days of the study . The registrant has submitted an interim report on the effects of in place sediment concentrations of fipronil on the re
- colonization of natural streams (MRID 46936104). The objective of the study was to evaluate the long
- term effects of fipronil on benthic macroinvertebrates in freshwater ecos ys tems. A total of ei ght separate surface water sites were considered in this evaluation. Surficial sediments were collected from each test site. These sediments were untreated (control), or treated with fipronil as a low dose 0.75 μg/kg (wet) or high dose 1.5 μg/kg (wet) and replicates of control and fipronil doses (3 each) were placed prepared using the aforementioned sediment placed into 700 ml tray s. These trays were then reintroduced to the test sites. The study reports have not been completed at the time of the draf ting of this risk assessment. j. In cidents There are few incidents in the Agency database for effects on non
- target organisms associated with the labeled use of fipronil. The degree to which the low number of ye ars of outdoor use contributes to a lack of incidents is unknown. In cident number I009142001 is a report of crayfish mortality following use of fipronil as

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### a seed treatment on rice in L ouisiana. The database classifies this incident as highl y probable. In March of 1999 L ouisiana Department of Agri culture and Safety issued a stop order to prevent the use of fipronil on rice seed in Allen, Calcasieu, Cameron, Lafayette, St. Martin, Iberia, St. Mary , St. L andry , Beauregard, Vermillion, Evangeline, Acadia, and Jefferson Davis Parishes. Fipronil was detected in 3 of 9 crawfish samples (mean detection 0.04 μg/kg). Fipronil was detected in water samples from 8 of 16 ponds (average 2,08 μg/L, high 6.09 μg/L), in all samples of the Mermentau River (average 1.67 μg/L, high 3.16 μg/L), and 14 of 17 other wat er monitoring sites (average 0.84 μg/L, high 5.33 μg/L). the registrant (Rhone
- Poulenc reported that 17 crawfish growers had reported to them observations of crawfish at the edges of ponds bordering rice fields planted with fipronil
- treated rice. The LA department of Agriculture was investigating 31 reported incidents pf crawfish kills on rice. Among the department and registrant reports there were 45 total incidents. The Louisiana state university Agricultural center conducted a survey

and several experiments which substantiated the link between fipronil
- treated rice seed and reduced survival of crawfish under hot dry weather conditions. Fipronil is no longer registered for rice seed treatment. There are two reports of corn crop damage (I011723098 300 acres in North Dakota, and I013103054300 550 acres in I daho) following use of fipronil Regent SC. These incidents are classified in the database as possible (Idaho incident) and probable (North Dakota). In neither incident report are there any confirmato ry residue analyses. One other probable incident, outside the United States, is also reported in the Agency database. Itinvolves locust control efforts on the island of Madagascar (I010380001). The incident was summarized in a BBC news article. The ar ticle refers to survey

results citing declines in the Madagascar bee eater and a kestrel species. In addition, surveys of termite colonies showed a 90% elimination rate ten months after spraying. There are no confirmatory

anal ytical data reported in the incident summary .