### registration review of pyridaben. This document recommends studies that should be included in a generic data call-in (DCI) to address uncerta inties surrounding the environmental fate and potential ecological effects of pyridaben.

-2 of 62-UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION



# Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments in Support of the Registration Review of Pyridaben

N

N CH 3 CH

3

CH 3 O

S Cl

C H 2 CH 3

CH 3 CH 3



## 2-tert-butyl-5-(4-tert-butylbe nzylthio)-4-chloropyridazin-3(2 H )-one CAS Registry Number: 96489-71-3
PC Code: 129105

Prepared by: Kristina Garber, Biologist Reuben Baris, Environmental Scientist Reviewed by: Brian Kiernan, Biologist Cheryl Sutton, Ph.D., Environmental Scientist Mark Corbin, Branch Chief ERB6 Marietta Echeverria, Acting Branch Chief ERB4 U. S. Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division
Environmental Risk Branch IV 1200 Pennsylvania Ave., NW
Mail Code 7507P Washington, DC 20460



### August 26, 2010

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### Table of Contents

1. Purpose..................................................................................................................... ............... 5
2. Problem Formulation ......................................................................................................... ..... 5 2.1. Nature of Regulatory Action........................................................................................... 5
2.2. Conclusions from Previous Risk Assessments ............................................................... 5 2.2.1. Ecological Risk Assessments.................................................................................. 5 2.2.2. Drinking Water Exposure Assessments.................................................................. 6
3. Stressor Source and Distribution ............................................................................................ 6
3.1. Mechanism of Action...................................................................................................... 6 3.2. Overview of Pesticide Use and Usage............................................................................ 7 3.3. Environmental Fate and Transport.................................................................................. 8 3.4. Degradates of Concern.................................................................................................. 10 3.5. Water Quality............................................................................................................. ... 11 4. Receptors................................................................................................................... ............ 12 4.1. Effects of Pyridaben to Aquatic Organisms.................................................................. 12 4.2. Effects of Pyridaben to Terrestrial Organisms.............................................................. 14 4.3. Effects of Pyridaben’s Degradates of Concern to Non-Target Organisms................... 15
4.4. Incident Databases Review........................................................................................... 15 4.5. Ecosystems Potentially at Risk ..................................................................................... 16 5. Consideration of Persistent, Bioaccumulativ e and Toxic Properties of Pyridaben .............. 16 6. Assessment Endpoints ........................................................................................................ .. 17 7. Conceptual Model............................................................................................................ ..... 18 7.1. Risk Hypothesis ........................................................................................................... . 18 7.2. Conceptual Diagram ..................................................................................................... 18 8. Analysis Plan ............................................................................................................... ......... 20
8.1. Stressors of Concern ..................................................................................................... 20 8.2. Measures of Exposure................................................................................................... 21
8.3. Measures of Effect ........................................................................................................ 22 8.4. Integration of Exposure and Effects ............................................................................. 23
8.5. Deterministic and Probabilistic Assessment Methods.................................................. 24 8.6. Endangered Species Assessments................................................................................. 24 8.7. Drinking Water Assessment ......................................................................................... 25 8.8. Preliminary Identification of Data Gaps....................................................................... 25
8.8.1. Environmental Fate Data ...................................................................................... 25
8.8.2. Effects Data........................................................................................................... 2 7
9. References.................................................................................................................. ........... 32
9.1. Scientific Literature and Government Publications...................................................... 32 9.2. Submitted Environmental Fate and Product Chemistry Studies................................... 33
9.3. Submitted Effects Studies............................................................................................. 34 APPENDIX A: Current Regi strations for Pyridaben................................................................... 37
APPENDIX B: Characterization of Envi ronmental Fate Data for Pyridaben ............................. 38
APPENDIX C: Characterization of Ecol ogical Effects Data for Pyridaben ............................... 43 APPENDIX E: PRZM/EXAMS Input Parameters...................................................................... 51
APPENDIX F: Data Call-In Tables............................................................................................. 52

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### 1. Purpose

The purpose of this problem formulation is to pr ovide an understanding of what is known about the environmental fate and ecological effects of pyridaben, considering its currently registered uses. Pyridaben is a selective contact insecticide a nd miticide that controls pests in apples, citrus (including non-bearing nursery beds), cranberries, grapes, pears (including Asian varieties), stone fruit ( e.g. , apricots, cherries, nectarines, peac hes, plums, and prunes), tree nuts ( e.g. , almond, beech, brazil, butternut, cashew, chestnut, chinquapin, filbert, hickory, macadamia, pecan, black walnut, English waln ut, and pistachios), and commercia lly grown ornamentals. This document provides a plan for analyzing data relevant to pyridaben and for conducting environmental fate, ecological risk, enda ngered species, and drinking water exposure assessments for its registered uses. Additionally, th is problem formulation is intended to identify data gaps, uncertainties, and poten tial assumptions used to address those uncertainties relative to characterizing the ecological risk associated with the registered uses of pyridaben.

2. Problem Formulation

2.1. Nature of Regulatory Action

Under the Federal Insecticide, F ungicide, and Rodenticide Act (FIF RA), all pesticid es distributed
or sold in the United States generally must be registered by the Environmental Protection Agency (EPA). In determining whether a pesticid e can be registered in the United States, the Agency evaluates its safety to non-target spec ies based on a wide range of environmental and health effects studies. In 1996, FIFRA was amended by the Food Quality Protection Act, and the Agency was mandated to implement a new program for the periodic review of pesticides, i.e

., registration review ( http://www.epa.gov/oppsrrd1/registration_review/ ). The Registration Review program is intended to ensure that, as th e ability to assess risk evolves and as policies and practices change, all register ed 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 Registration Review program, the Agency periodically reevaluates pestic ides to make sure that as change occurs, products in the marketplace can be used safely.

As part of the implementation of the Registratio n Review program pursuant to Section 3(g) of the Federal Insecticide, Fungicide and Rodentic ide Act (FIFRA), the Agency is beginning its evaluation of pyridaben to determine whether it continues to meet the FIFRA standard for registration. This problem formulation for the environmental fate, ecological risk, endangered species, and drinking water exposure assessments in support of the registration review will be posted in the initial docket that will open the public phase of the review process.

2.2. Conclusions from Previous Risk Assessments

2.2.1. Ecological Risk Assessments

Pyridaben is a contact insecticide/miticide that was first registered in 1996 for use on citrus groves, apple orchards, pears, and almonds (Case No. 015679). In 2004, an ecological risk assessment was conducted for proposed new uses of pyridaben on strawb erries, hops, tropical

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### fruit, and stone fruit (D285563+). The assessment c oncluded that pyridaben (parent only), at the proposed maximum use rates, exceeds acute and ch ronic risk levels of concern for freshwater fish and invertebrates, acute risk for estuarine/ma rine fish and invertebrates, and chronic risk for birds and mammals for the proposed uses.

EFED recently (August 2010) completed an ecological risk assessment of a special local needs use of pyridaben on pears in the state of Wash ington. This assessment concluded that based on maximum application rates, exposure levels and available effects data, pyridaben applied to pears in Washington at 0.75 lb a.i./A, has the pote ntial to cause effects to survival, growth and reproduction of aquatic animals and terrestrial ma mmals and effects to the reproduction of birds, terrestrial-phase amphibians and reptiles. This includes non-listed and li sted species. Because pyridaben is highly toxic to bees on an acute exposu re basis, there is potential for acute effects to
beneficial insects. Effects to non-listed terrestr ial and wetland plants ar e not expected; however, risks to listed plants cannot be precluded. Because no toxicity data are available to characterize the effects of pyridaben to aquatic plants, risks to aquatic plants cannot be precluded. There is also potential for indirect effect s to species that depend on those th at may be directly affected by pyridaben (i.e., fish, aquatic and terrestr ial invertebrates, mammals and birds).

2.2.2. Drinking Water Exposure Assessments

The Agency conducted three drinking water expo sure assessments for pyridaben from 1999 to 2004 in support of the establishment of toleran ces for use on cranberries, and the proposed new uses on strawberries, hops, tropical fruit, and stone fruit (USEPA, 1999a&b; USEPA, 2004a). The most recent assessment (USEPA, 2004a) re ported screening-level acute and chronic concentrations of pyridaben in surface wate r at 5.5 μg/L and 1.4 μg /L, respectively, and a screening-level ground water con centration of 0.006 μg/L, which is the same concentration reported for ground water in the 1999 a ssessments (D258903 & D259315). The Agency concluded that pyridaben is not likely to be a significant ground water contaminant. However, the Agency noted that compounds such as pyridaben with K
oc 

### values greater than 9995 ml/g are beyond the scope of the regression data used in SCI-GROW developmen t; therefore, if ground water contamination by pyridaben is a concer n, the Agency recommended a higher tier ground water exposure assessment be considered, regard less of the concentrat ion returned by SCIGROW. In the 2004 assessment, estimated dri nking water concentra tions (EDWCs) were reported for pyridaben only (parent only). Degradat es identified by the Hea lth Effects Division to be of toxicological concern (P B 7 and PB9) were not included in the drinking water assessment since they were not identified in fate studies great enough to impact environmental modeling inputs for pyridaben.

3. Stressor Source and Distribution

3.1. Mechanism of Action

Pyridaben is a selective contact pesticide used to control a wide variety of mites and other
insects. It is an inhibitor of glutamate-dependent mitochondrial respiration in both vertebrates and invertebrate systems and specifically inhibits NADH:CoQ oxi doreductase activity (Hollingworth et al. 1994).

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### 3.2. Overview of Pesticide Use and Usage

Currently, there are seven national registrations (S ection 3) for formulated products that contain pyridaben. These formulations are water sol uble packets, wettable powders, or aqueous suspensions. There are three registrations for technical pyridaben that are used to create formulated products. In additi on, there are six special local needs [SLNs; Section 24(c)] registrations. These special local needs regist rations apply to greenhous e tomatoes grown in Arizona, Maine, Minnesota, Pennsylvania, and Texas, and pears grow n in Washington. The greenhouse uses will not be considered in ecological risk assessments asso ciated with pyridaben since exposure to non-target organisms is not exp ected from the greenhouse uses of pyridaben. A list of the registrati ons is provided in Appendix A

.

Pyridaben is registered for use on citrus, cranberr ies, grapes, stone fruits and tree nuts applied twice at a single maximum application rate of 0.5 lb a.i./A (annual ma ximum rate is 1.0 lbs a.i./A/yr). Pyridaben is also registered on apples and pears for one applic ation (per season) at a maximum single application of 0.5 lb a.i./A. Curr ently, there is an active SLN in Washington for pears that allows for one application (per seas on) at a maximum single application of 0.75 lb a.i./A. Pyridaben is also registered for use on commercially grown ornament al plants at a single maximum rate of 1.0 lb a.i./A (per season). A pplications are allowed by ground spray only, with the exception of chemigation applications that may be made to cranberries. Aerial applications of pyridaben are prohibited on product labels. Max imum single application rates for pyridaben, number of applications per year , application intervals and app lication methods are provided in
Table 3.1

.

TABLE 3.1. Maximum Use Patterns and Genera l Management Practices for Pyridaben.

Use Single max application rate (lb a.i./A) Number of app.

per year Application interval (d) Annual max application rate

(lbs a.i./A/yr) Application method(s)

Almonds 0.5 2 30 1.0 Ground spray
Apples 0.5 1 30 0.5 Ground spray

Apricots 1 0.5 2 30 1.0 Ground spray

Beech Nut 0.5 2 30 1.0 Ground spray

Brazil Nut 0.5 2 30 1.0 Ground spray

Butternut 0.5 2 30 1.0 Ground spray

Cashew 0.5 2 30 1.0 Ground spray

Cherries 1 0.5 2 30 1.0 Ground spray

Chestnut 0.5 2 30 1.0 Ground spray
Chinquapin 0.5 2 30 1.0 Ground spray

Citrus 0.5 2 90 1.0 Ground spray

Cranberries 2 0.5 2 30 1.0 Ground spray, chemigation

Filbert 0.5 2 30 1.0 Ground spray

Grapes 0.5 2 30 1.0 Ground spray

Hickory 0.5 2 30 1.0 Ground spray

Macadamia 0.5 2 30 1.0 Ground spray

Nectarines 0.5 2 30 1.0 Ground spray

Peaches 0.5 2 30 1.0 Ground spray

Pear 0.5 1 30 0.5 Ground spray
Pear (SLN) 3 0.75 1 30 0.75 Ground spray



### -7 of 62-Use Single max application rate (lb a.i./A) Number of app.

per year Annual max Application Application application rate interval (d) method(s) (lbs a.i./A/yr)

Pecan 0.5 2 30 1.0 Ground spray

Pistachio 0.5 2 30 1.0 Ground spray

Plums 0.5 2 30 1.0 Ground spray

Prunes 0.5 2 30 1.0 Ground spray

Ornamental Plants 4 1.0 1 No successive

treatments 1.0 Ground spray

Stone Fruit 0.5 2 30 1.0 Ground spray

Walnut (Black and English) 0.5 2 30 1.0 Ground spray

NA = not applicable SLN = special local needs registration

1 Except in California.

2 Allowed only in CT, DE, ME, MA, NH, NJ, RI, and VT.

3 Allowed in Washington only.

4 Use on greenhouse and outdoor orname ntal plants and foliage crops.



### 3.3. Environmental Fate and Transport

Pyridaben (2-tert-butyl-5 -(4-tert-butylbenzylthio)-4 -chloropyridazin-3(2H)-one, CAS RN: 96489-71-3) is a semi-vol atile, hydrophobic compound that is hardly mobile in soil based on the FAO soil mobility classifications (K
oc 

### ’s >10,000) (USEPA, 2006). Pyridaben is semi-volatile, with a vapor pressure of 8.21 x 10 -5 

### torr (MRID 42676103) and a unitless Henry's Law Constant of 0.07 (calculated) . However, based on the compound 's tendency to sorb to soil (Koc > 10,000; MRID 42680155) and plants (Log Kow = 6.37; MRID 42676103), pyridaben is not expected to volatilize when applied to the surf aces of soil or plants. Pyridaben dissipates in the environment through abiotic and biotic degr adation (primary route of degradation is photolysis, both aqueous and from soil). The com pound is persistent in aerobic soil (half-life of 110 days). Pyridaben is stable to hydrolysis at pH 5, 7, and 9. Th e persistence of pyridaben in aquatic environments (both aerobic and anaerobic) is uncertain as there are no acceptable studies available that report this data. However due to its high tendency to bind to soil, it is likely to partition quickly to the sediment in aquatic environments. Terre strial field dissipation data indicate that the compound dissipa tes, with dissipation half-lives (DT50s) in the top 12” of soil ranging from 12 to 14 days (DT90s ranged from 120 to 629 days); the compound was not
detected below 12”. The field studies illustrate that initially pyridaben degrades rather quickly, but tends to persist much longer at lower con centrations once the DT50 has been achieved (i.e., the compound degrades much sl ower after the initial DT50).

Table 3.4 summarizes the submitted environmental fate data for pyridaben. Additional
characterization of the submitted environmental fate data is located in Appendix B

.

There was one major degradate (4-tert-butyl benzyl a1coho1, B-3) was identified in the definitive aqueous photolysis study, however it was not found at >10% in the quantitative portion of the study. There were no major degradat es of pyridaben identi fied in the remaining
environmental fate studies. There were several minor degradates that were identified, some with concentrations approaching 10% of th e applied at the study termination ( e.g. , PB-4). These compounds include:

• 2-tert-Butyl-5-(4-tert-butylbenzylsulfinyl )-4-chloropyridazin-3(2H)-one (PB-4),



### -8 of 62-• 2-tert-Butyl-5-[4-(1-carboxy-1-methylethyl)benzylthio]-4-chloropyridazin-3(2H)-one (PB-7),

• 2-tert-butyl-4-chloro-5-[4-(1,1-dimethyl-2-hydrox yethyl) benzylthio]pyridazin-3(2H)-one (PB-9),

• 2-tert-Butyl-4-(4-tert-butylbenzoyl)-pyridazin-3(2H)-one-5-sulfonic acid (P-14),

• 2-tert-Butyl-4-(4-tert-butylbenzyl)-pyridazi n-3(2H)-one-5-sulfonic acid (PB-14), and

• 4-Chloropyridazin-3(2H)-one-5-sulfonic acid (PB-16).



### Bioconcentration data are available from two se parate BCF laboratory st udies involving rainbow trout (MRID 43792113). After 28 days of exposure to pyridaben (0.11 μg a.i./L), whole fish BCF values (based on total radioactivity) we re 342 and 439 (μg/kg-ww per μg/L). Metabolites were identified in the fish tissue; however, their levels were not quantifie d. Identified metabolites included: PB-5, PB-7, PB-9, PB-10, PB-11, PB-12 a nd PB-13. In a life cycle test with fathead minnows ( Pimephales promelas ), BCF values ranged 1168 to 3780 in larval and adult fish exposed to pyridaben (MRID 43792106).

As discussed in USEPA 2008, several authors, including Kelly and Gobas (2003), Armitage and Gobas (2007) and Kelly et al . (2007), conclude that chemicals with Log K OA 

### >5 and Log K OW 

### >2 may biomagnify in terrestrial food chains. The estimated Log K OA 

### of 9.1 (EPIsuite, v.4.0) combined with the measured Log Kow value of 6.37 suggest that bioaccumulation of pyridaben in air-breathing organisms is possible. As with aquatic organisms, bioaccumulation may be limited by metabolism of pyridaben.

TABLE 3.4. General Chemical Properties an d Environmental Fate Properties of Pyridaben.

Parameter Value Reference (MRID #)

Physical/Chemical Parameters

Molecular mass 364.9 42676103
Vapor pressure (20°C) 8.21 x 10 -5 torr 42676103
Henry’s Law Constant (20oC) 6.84 x 10 -3 Calculated (VP/Wsol)

Water solubility (20°C) 0.012 mg·L -1 42676103
Octanol-water partition coefficient (K OW ) (25°C, pH not reported) 2,344,228 Log K
ow = 6.37 42676103

Mobility
Organic carbon partitioning coefficient (K OC, L·kg
1 ) 64,600 (sand) 34,900 (sandy loam) 87,900 (silt loam, low CEC) 78,700 (silt loam, high CEC) 42680155

Persistence in Water
Hydrolysis half-life (25°C, pH 5, 7, & 9) Stable 42680153
Aqueous photolysis half-life (25°C) 0.06 day † 43680427
Aerobic aquatic metabolis m half-life no data none Anaerobic aquatic metabolis m half-life no data none

Persistence in Soil
Soil photolysis half-life (25°C) 11 days 43792110

Aerobic soil metabolism half-life (25°C) 110 days 42680154

Anaerobic soil metabolism half-life (25oC) Stable 43680128

Field Dissipation
Terrestrial field dissipa tion half-life; maximum leaching depth 14 days; 0-12” (CA citrus) 12 days; 0-6” (FL Citrus) 43680430



### -9 of 62-Parameter Value Reference (MRID #)

Aquatic Bioconcentration

Bioconcentration Factor (BCF) in fish 342-439
1168-3780 43792113,
43792106

† The previously accepted study on aqueous photolysis (MRID 436804-27) used acetone (a known photosensitizer) as a co-solvent an d reported a halflife of 5.3 minutes. A preliminary study in the same submi ssion, however, used acetonitrile as a co-solvent, and EFED deter mined the halflife to be 40 minutes for this study. Therefore input would be co rrected to account for partial sunlight (720 minutes), thus 0. 06 day.



### 3.4. Degradates of Concern

HED has identified two degradates of concern: PB -7 and PB-9 to be included in the drinking water exposure assessment (D230656). Both degrad ates are similar in structure to parent pyridaben. These degradates are considered of to be of concern in the ec ological risk assessment of pyridaben. However, the estimated environm ental concentrations (E ECs) generated in the ecological assessment will use environmental fate data for the parent only, since these two degradates were found at such low concentratio ns in the aerobic and anaerobic soil metabolism studies. Half-lives calculated for pyridaben do not differ from half-lives calculated for total residues of concern (i.e., pyridaben + PB-7 + PB-9). Thus adding them into the exposure expression would not impact the es timated exposure concentrations.

Table 3.5. Estimated (using EpiSuite v.4.0) Ch emical Properties of Pyridaben and Its Degradates of Concern

Parameter (units) Pyridaben (measured)* PB-7** PB-9***

Molecular mass (g/mol) 364.9 352.8 338.9
Vapor pressure (Torr, 25°C) 2.9e-8 (8.21 x 10 -5 ) 1.1e-10 6.4e-12

Water solubility (mg/L @ 25°C) 0.018 (0.012) 6.9 40.2

Octanol-water partition coefficient (Log K OW ) (25°C) 5.5 (6.4) 3.4 2.6

*measured values from Table 3.4 provided in parentheses for reference purposes. **Smiles code: c1cc(C(O)=O)ccc1CSC2=C(Cl)C(=O)N(C(C)(C)C)N=C2 ***Smiles code: c1cc(CO)ccc1CSC2=C(Cl)C(=O)N(C(C)(C)C)N=C2

N

N CH 3 CH

3

CH 3 O

S Cl

C H 2 CH 3

CH 3 CH 3



### Pyridaben

-10 of 62-N

N CH 3 CH

3

CH 3 O

S Cl

C H 2 CH 3

CH 3 O

OH



### PB-7

N

N CH 3 CH

3

CH 3 O

S Cl

C H 2 CH 3

CH 3 H2

OH



### PB-9

Figure 3.1. Structures of Pyrida ben and Its Degradates of Concern for Drinking Water and Ecological Risk Assessments.

3.5. Water Quality

Pyridaben is not identifie d as a cause of impairment for any water bodies under section 303(d) of
the Clean Water Act 1 

### . In addition, no Total Maximum Daily Loads (TMDL) have been developed for pyridaben 2 

### and there are no aquatic life criteria for pyridaben 3 

### . More information on impaired water bodies and TMDLs can be found at http://www.epa.gov/owow/tmdl/

.

The Agency invites submission of water quality data for this pesticide. To the extent possible, data should conform to the quality standards in Appendix A of the OPP Standard Operating Procedure: Inclusion of Im paired Water Body and Other Water Quality Data in OPP’s Registration Review Risk A ssessment and Management Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf ), in order to ensure they can be used quantitatively or qual itatively in pesticide risk assessments.

No monitoring data were available for pyridab en. Neither the USGS’s NAWQA program nor the California Department of Pesticide Regulation monitoring studies included pyridaben as an analyte.

1 based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 , accessed Jan. 26, 2010

2 based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl _pollutant_detail?p_pollutant_group_id=885&p_pollutant_ group_name=PESTICIDES , accessed Jan. 26, 2010

3 based on information provided at http://www.epa.gov/waterscien ce/criteria/aqlife/index.html



### -11 of 62-

### 4. Receptors

Consistent with the process described in th e Overview Document (USEPA, 2004b), the risk assessment for pyridaben relies on a surrogate sp ecies approach. Toxicological data generated from surrogate test species, which are intended to be representative of broad taxonomic groups, are used to extrapolate the pot ential effects on a variety of species (receptors) included under these taxonomic groupings. To adequa tely capture the risk from pyrid aben use, the toxicity and potential exposure of non-target animals to pyridaben will be considered. The most sensitive endpoints from the available toxicity data for pyridaben will be used to quantify risk.

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 pyridaben to aquatic and terrestrial receptors. This in cludes toxicity on the technical grade active ingredient, degradates, and when available, formulated products. The ope n literature studies are identified through EPA’s ECOTOXicology (ECOT OX) database, which employs a literature search engine for locating chemical toxicity data for aquatic life, terrest rial plants, and wildlife (USEPA, 2007 f

). The evaluation of both sour ces of data may also provid e insight into the direct and indirect effects of pyridaben on biotic commun ities from loss of species that are sensitive to the chemical and from changes in structure a nd functional characteristics of the affected communities. A preliminary review of open literature data from ECOTOX on pyridaben was conducted as part of this Problem Formulation to help identify data gaps. Nine studies were
identified in ECOTOX. These stud ies contain effects data for terrestrial invertebrates, aquatic animals and algae. A more complete review of the data from ECOTOX will be conducted for evaluation for possible quantitative and/or qua litative inclusion in this risk assessment.

A summary of the most sensitive data representing non-target orga nisms exposed to pyridaben in aquatic and terrestrial habitats is provided in Sections 4.1 and 4.2 . Additional toxicity data are
summarized in Appendix C . A summary of ecological incidents associated with pyridaben and a description of ecosystems potentia lly at risk are provided in Sections 4.3 and 4.4 , respectively.

4.1. Effects of Pyridaben to Aquatic Organisms

Pyridaben is very highly toxic to fish and invertebrates (fresh water and estuarine/marine) on an acute exposure basis. Chronic toxi city data are available from a full life cycle test conducted with the fathead minnow ( Pimephales promelas ). Growth (length and weight) of the F 0 

### and F 1 

### generations, as well as survival of the F 1 

### generation were significan tly decreased relative to controls at 0.555 μg a.i./L (NOAEC = 0.277 μg a.i./L; MRID 43792106). Because the rainbow trout ( Oncorhynchus mykiss 

### ) is more sensitive on an acute exposure basis when compared to the fathead minnow, the acute to chronic ratio (A CR; 8.3) from MRID 43792106 is used to derive a chronic endpoint for the rainbow trout which is 0.087 μg a.i./L. In a chronic study with the water flea ( Daphnia magna ), time to reproduction was significan tly affected at 0.086 μg a.i./L (NOAEC = 0.044 μg a.i./L; MRID 43680408). In a chronic study with mysid shrimp ( Mysidopsis bahia ), no reproductive, growth or survival effects were observed in exposures as high as 0.13 μg a.i./L (MRID 43680409). No data ar e available to quantif y the toxicity of pyridaben to sediment-dwelling invertebrates. In a Tier II test with green algae ( Selenastrum

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### capricornutum), an EC 50 

### was estimated as >665 μg a.i./L. A Ti er I toxicity test with duckweed ( Lemna gibba ) exposed to 16.2 μg a.i./L pyridaben resulted in a no decrease in frond production compared to the solvent control and a 7% decrease in frond produc tion compared to the negative
control. The most sensitive acute and chronic toxicity endpoints for aquatic animals and plants exposed to pyridaben are provided in Table 4.1 . These endpoints may be considered for calculating risk quotients in future risk assessments of pyridaben.

TABLE 4.1. Summary of the Most Sensitive Endpoints from Submitted Aquatic Toxicity Studies for Pyridaben.

Taxa represented Species (common name) Toxicity Value (μg a.i./L) Citation (MRID) Comments

96-hr LC 50 = 0.72 43680402 Slope = 6.9 (95% C.I. = 4.4-9.3)

freshwater fishand aquaticphase amphibians Oncorhynchus mykiss (rainbow trout) NOAEC = 0.087 See

comments Acute and chronic toxicity data are
available for fetched minnows ( Pimephales promelas ) exposed to pyridaben (96-h LC50 = 2.3 μg a.i./L; NOAEC = 0.277 μg a.i./L; ACR = 8.3; MRID 43792106). B ecause the rainbow
trout is more sensitive on an acute exposure basis, the ACR is used to derive
a NOAEC for the rainbow trout.

48-hr EC 50 = 0.53 42680111 Slope = 6.4 (95% C.I. = 4.2-8.6)
freshwater
invertebrates Daphnia magna (waterflea) NOAEC = 0.044 43680408 Study classification is Acceptable. LOAEC = 0.086 μg/L based on delayed time to reproduction.

96-hr LC 50 = 17.2 43680406 Slope = 4.7 (95% C.I. = 2.2-7.2)
Estuarine/
Marine fish Cyprinodon variegates (Sheepshead minnow) NOAEC = 2.1 See

comments Derived using ACR for fathead minnow (8.3) and acute toxicity value for sheepshead minnow.

96-hr EC 50 = 0.67 43680405 Slope = 3.1 (95% C.I. = 1.8-4.5) Estuarine/
Marine
Invertebrates Mysidopsis
bahia (mysid shrimp) NOAEC = 0.13 43680407 A LOAEC was not established in this study because no effects were observed at any treatment level.

Selenastrum capricornutum (green algae) EC 50 >665
NOAEC <20.8 43680421 Due to a poor dose-response relationship,
a reliable EC 05 could not be calculated.

Aquatic Plants Lemna gibba (duckweed) EC 50 and

NOAEC >16.2 43680422 Estimated from tier 1 test where no biologically significant effects to duckweed were observed at 16.2 μg
a.i./L. Note that these effects values are greater than pyridaben’s solubility in water (i.e., 12 μg/L).



### -13 of 62-

### 4.2. Effects of Pyridaben to Terrestrial Organisms

Pyridaben is classified practical ly non-toxic to birds on an acut e oral exposure basis. On a subacute dietary basis, pyridaben is classified as slightly toxic to birds. Reproductive (decreases in eggs laid, eggs set, viable embryos, live 3 week embryos, normal hatchlings and hatch survival) and parental effects (decrease in size of adult male testes and decrease in number of female ovaries) were observed in mallard ducks fed pyridaben at levels as low as 500 mg/kg-diet (LOAEC). The resulting no observed adverse e ffects concentration (NOAEC) was 100 mg/kgdiet.

Pyridaben is moderately toxic to mammals on an acute oral exposure basis. In a 2-generation reproduction study, the LOAEC for pyridaben pare ntal toxicity was 80 mg/kg-diet based on decreased body weights, body weight gains a nd food efficiency. The resulting NOAEC was 28 mg/kg-diet. No reproductive effects were observed at any test leve l, resulting in a reproductive LOAEC >80 mg/kg-diet.

Pyridaben is highly toxic to honey bees (LD 50 

### = 0.024 μg a.i./bee). Available foliar residue studies indicate that pyridaben can cause mort ality (> 20%) in honey bees up to 24 hours after application (MRID 43680424).

Seedling emergence and vegetative vi gor data are available for 6 sp ecies of dicots and 4 species of monocots exposed to technica l pyridaben (MRIDs 436804-19 and - 20). In these studies, <25% decrease in dry weight was obser ved in plants exposed to 0.5 lb a.i./A pyridaben (compared to controls). Because no data are avai lable at the highest single applic ation rate (i.e., 1.0 lb a.i./A), there is uncertainty in the potential effects of pyridaben on terrestrial plants.

The most sensitive acute and chronic toxicity endpoints for terrestrial animals exposed to pyridaben are provided in Table 4.2. These endpoin ts may be considered for calculating risk quotients in future risk a ssessments of pyridaben.

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### TABLE 4.2. Summary of the Most Sensit ive Endpoints from Submitted Terrestrial Toxicity Studies for technical Pyridaben.

Taxa represented Species Toxicity Value Citation (MRID) Comments

LD 50 >2500 mg/kgbw 42680105

LC 50 = 4688 mg/kg-diet 42680107 Birds, terrestrial-phase amphibians and reptiles Anas platyrhynchos (Mallard Duck)

NOAEC = 100 mg/kg-diet 43792101 LOAEC = 500 mg/kg-diet based on reproductive and parental
effects

Mus sp. (mouse) LD 50 = 383 mg/kg-bw Female 42680120 LD 50 for males = 424 Study conducted with TGAI

Terrestrial
mammals Rattus norvegicus (laboratory rat) NOAEC = 28 mg/kg-diet 42680143
42680144 NOAEL = 2.2 and 2.4 mg/kgbw/day for males and females respectively LOAEC = 80 mg/kg-diet based on parental effects. No reproductive
effects were observed. LOAEL = 6.3 and 7.8 mg/kg-bw for males and females, respectively

Terrestrial
invertebrates Apis mellifera (Honey bee) LD 50 = 0.024 μg/bee 43680423 Slope = 3.31

Non-target
terrestrial and wetland plants 10 species of
monocots and
dicots EC 25 >0.5 lb a.i./A 43680419
43680420 <25% effects to dry weight were observed in all 10 test species for Tier 1 seedling emergence and vegetative vigor tests.



### 4.3. Effects of Pyridaben’s Degradates of Concern to Non-Target Organisms

As stated previously, HED has identified PB-7 and PB-9 as degradates of concern for human health. No empirical data are available from registrant-submitted studies or from the literature to characterize the toxicity of PB-7 and PB-9 to non-target organisms. ECOSAR (v.1.0) and
ASTER were run to estimate the toxicity of these degradates to aquatic organisms (Appendix D). When the estimated toxicity values genera ted by ECOSAR and ASTER are compared to available empirical data (Table 4.1), both tool s predict acute toxicity values for fish and invertebrates exposed to pyridaben that are 1-2 or ders of magnitude less toxic when compared to empirical data. This suggests that ECOSAR and ASTER may not be appropriate tools for estimating the toxicity of pyridaben and its degrad ates. Therefore, in the absence of data to the contrary and given the structural similarities of PB-7 and PB-9 to the parent, it will be assumed that the toxicities of PB-7 and PB-9 are equivale nt to that of pyridaben. Available toxicity data for pyridaben (Tables 4.1 and 4.2) will be used as surrogates for characteri zing the effects of PB7 and PB-9 to non-target aquati c and terrestrial organisms.

4.4. Incident Databases Review

Searches of the EIIS (Environm ental Incident Information System) database for ecological incidents (run on April 27, 2010) and AIMS (run on August 9, 2010) identified no incidents

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### involving pyridaben. One note of un certainty associated with thes e databases is the nature of reporting of incidents. Pyridabe n exposure incidents may have oc curred that were not reported due to various factors, such as a lack of reporting, or a lack of witnessing of effects. Therefore, the absence of incident reports does not neces sarily indicate the absence of incidents.

4.5. Ecosystems Potentially at Risk

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

Aquatic ecosystems potentially at risk include water bodies and sediment adjacent to, or down stream from, the treated site and might in clude impounded bodies such as ponds, lakes and reservoirs, or flowing waterways such as streams or rivers including all adjacent off-channel habitats that are permanently or intermittently co nnected to flowing waters. For uses in coastal areas, aquatic habitat also incl udes marine ecosystems, including estuaries, embayment’s, and
near shore environments.

5. Consideration of Persistent, Bioaccumula tive and Toxic Properties of Pyridaben

The EPA’s PBT Profiler is a screening-level tool that provides estimates of the persistence, bioaccumulation, and chronic toxicity to fish. When pyridaben is run through the PBT profiler, the tool indicates that pyridaben may have pers istent, bioaccumulative and toxic characteristics. This conclusion is supported by empirical enviro nmental fate and effects data available for pyridaben.

For pyridaben, the persisten ce conclusion is based on the estimatedaerobic metabolism halflives for sediment, water and soil (Table 5.1); th is does not account for photodegradation in soil, which could be a significant degradation pathwa y in the natural environment during periods of intense light. Empirical data are available froman aerobic soil metabolism study where the halflife (110 d) was a 92% of the estimated value (120 d); however, both the estimated and the empirical soil metabolism half-lives are sufficient to consider pyridaben persistent according to the PBT profiler’s definition ( i.e. , t 1/2 

### ≥ 60 d). No empirical aquatic or sediment metabolism data are available for which to compare the estimated half-lives for these media.

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### Table 5.1. Estimated (via PBT profiler) and empi rical half-lives (in days) for pyridaben in
different media.

Media Estimated Empirical

Water* 60 No data

Soil* 120 110**

Sediment* 540 No data

Air 0.37 No data

*Represents biodegradation. Estimate d using BIOWIN; this estimate doe s not account for photodegradation.
**MRID 42680154



### The bioaccumulation conclusion for pyridaben is based on an estimated BCF for fish of 16,000. The PBT profiler’s threshold for concluding that a chemical is bioaccumulative is a BCF of 1000. Empirical BCFs from two separate laborat ory studies involving rainbow trout (MRID 43792113) were 342 and 439. In a life cycle test with fathead minnows ( Pimephales promelas ), BCF values ranged 1168 to 3780 in larval a nd adult fish exposed to pyridaben (MRID 43792106). Differences in BCF values observed in the 30-d rainbow trout and full life cycle fathead minnow tests may be attributed to th e durations of the studi es. Based on the Kow of pyridaben, the time required to reach steady stat e may be greater than 30 days, which would result in underestimation of BCF values obtained from the rainbow trout studies. Regardless of these differences, empirical BCF values are 1-2 orders of magnitude below the PBT profiler’s
estimated BCF. One reason for this overestimate ma y be a lack of consideration of metabolism of pyridaben by fish, which was observe d in the laboratory BCF study. KABAM ( K OW 

### (based)

A quatic B io A ccumulation M odel; version 1.0) was used to estim ate a fish BCF that considers metabolism (see Appendix B). When the metabolism rate is estimated from the empirical BCF studies, estimated BCF for fish is 5740, which is on the same order of magnitude as the empirical
BCF values observed in fathead minnows. A lthough metabolism reduces the bioconcentration potential of pyridaben, the estimated and empiri cal BCF data are still sufficient to consider pyridaben bioaccumulative ( i.e. , BCF ≥ 1000) according to the PB T profiler’s definition.

The PBT profiler consider s a chemical “toxic” when its ch ronic value is below 10,000 μg/L. The chronic value is the geometric mean of the NOAEC and LOAEC from a chronic fish study ( i.e. the MATC). The estimated chronic value for pyrid aben is 4 μg/L. The MATC from the full life cycle test conducted with the fathead minnow exposed to pyridaben was 0.392 μg/L (MRID 43792106), which is an order of magnitude below th e PBT profiler’s estimated chronic value.

6. Assessment Endpoints

Assessment endpoints represent the ac tual environmental value that is to be protected, defined by an ecological entity (species, community, or othe r entity) and its attri bute or characteristics (USEPA, 1998). For pyridaben, the ecological entities may include th e following: birds, mammals, terrestrial-phase amphibian s, reptiles, freshwater fish a nd invertebrates, aquatic-phase amphibians, estuarine/marine fish and invertebrate s, terrestrial plants, terrestrial invertebrates, and aquatic plants. The attributes for each of these entities include growth, reproduction, and survival. The proposed assessment endpoi nts for pyridaben are provided in Tables 4.1 and 4.2

. No endpoints have been established for aquatic plants.

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### 7. Conceptual Model

For a pesticide to pose an ecological risk, it mu st reach ecological receptors in biologically significant concentrations. An exposure pathway is the means by which a pesticide moves in the environment from a source to an ecological recepto r. 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, an d a feasible route of exposure.

The conceptual model for pyridaben provides a wr itten description and visual representation of the predicted relationships betw een pyridaben, potential routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model consists of two major components: a risk hypothesis and a conceptual diagram (USEPA, 1998).

Based on the submitted environmental fate data and previous assessments in support of the original registration and Section 24c registrations, the pyridaben va por pressure suggests that the chemical is semi-volatile; however, it is not expect ed to volatilize due to its tendency to sorb to soil (high Koc) and plants (high Koc and Kow). Gi ven that pyridaben will sorb to soil, there is potential for it to be transported via wind eroded soil with sorbed compound, thus may be a concern for long range transport. Persisten ce in aqueous environments is uncertain. The compound is unlikely to leach to ground water due to its adsorptive potential, however it may move to surface water bodies through spray drift, and/or in runoff events that are accompanied by erosion. Estimated and empirical bioconcentr ation data indicate that bioaccumulation of pyridaben may occur, but it will be significan tly reduced by metabolism of the compound by aquatic organisms. A previous ecological risk assessment conc luded that pyridaben (parent only), at the maximum use rates, exceeds acute and chronic risk levels of concern for freshwater fish and invertebrates, acute risk for estuarine/ma rine fish and invertebrates, and chronic risk for
birds and mammals.

7.1. Risk Hypothesis

A risk hypothesis describes the predicted re lationship among the stre ssor, exposure, and assessment endpoint response along with the rati onale for their selection. For pyridaben, the following hypothesis will employed for the ecolo gical risk assessmen t associated with registration review:

Given the uses of pyridaben and its environmen tal fate properties, th ere is a likelihood of exposure of non-target terrestrial and aquatic organisms to pyridaben and its degradates of concern (PB-7 and PB-9). When used in a ccordance with the labe l, pyridaben results in potential adverse effect s upon the survival, growth, and reproduction of non-target terrestrial and aquatic organisms.

7.2. Conceptual Diagram

The environmental fate properties of pyridaben indi cate that runoff, spray dr ift, and direct spray represent potential transport mech anisms of pyridaben to aquatic and terrestrial habitats where non-target organisms may be exposed. The potential transport mechanisms ( i.e ., sources) of

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### pyridaben are depicted in the conceptual models below ( Figures 7.1 and 7.2 ) along with the receptors of concern and the potential attribute changes in the receptors due to exposures of pyridaben.

Pyridaben applied to use site Degradation to PB-7 and PB-9

Spray drift

Fish/aquatic-phase amphibians Eggs

Larvae
Juveniles / Adults

Individual organisms
Reduced survival Reduced growth Reduced reproduction Food chain Reduction in algae Reduction in prey Habitat integrity Reduction in primary productivity
Reduced cover Community change Surface water/

Sediment Runoff

Aquatic Animals
Invertebrates
Vertebrates Uptake/gills or integument

Ingestion Ingestion Long-range atmospheric

transport

Wet/dry deposition Soil Ground water

Uptake/gills or integument

Aquatic Plants

N on-vascular
Vascular Uptake/cell, roots, leaves Riparian plant
terrestrial

exposure pathways (see

Figure 6.2 ) 

### Stressor

Source

Exposure
Media

Receptors

Attribute Change

FIGURE 7.1. Conceptual Model for Pyridaben Effects on Aquatic Organisms. Dotted Lines Indicate Exposure Pathways that H ave a Low Likelihood of Contributing to Ecological Risk.

-19 of 62-Pyridaben applied to use site 

### Stressor Degradation to PB-7 and PB-9



### Source

Receptors

Attribute Change Direct application Spray drift

Birds / Terrestrialphase amphibians / reptiles / mammals Terrestrial
invertebrates

Individual organisms
Reduced survival Reduced growth Reduced reproduction Food chain Reduction in prey Habitat integrity Reduction in primary productivity
Reduced cover Community change Terrestrial/riparian plants grasses/forbs, fruit, seeds (trees, shrubs) Runoff

Mammals 

### Exposure
Media Soil

Ingestion Ingestion

Ingestion Ingestion Dermal uptake/Ingestion Long-range atmospheric

transport

Root uptake
Wet/dry deposition

Birds / Amphibians

Ingestion



### FIGURE 7.2. Conceptual Model for Pyridaben Effects on Terrestrial Organisms.

8. Analysis Plan

In order to address the risk hypot hesis, the potential for adverse effects on the environment is estimated. The use, environmental fate, and ecologi cal effects of pyridaben are characterized and integrated to assess the risks. Risk quotients (RQs) will be derived for pyridaben residues of concern by dividing estimated environmental concentrations (EEC) by the most sensitive endpoint from the relevant, available toxicity data for the pyridaben residues of concern.

This analysis plan will be re visited and may be revised dependi ng upon a full review of the data available in the open literature and the inform ation submitted by the public in response to the opening of the Registration Review docket.

8.1. Stressors of Concern

Pyridaben and its degradates PB-7 and PB-9 are c onsidered the stressors of concern in the risk assessment. The PB-7 and PB-9 degradates are identified as stressors of concern for drinking water and ecological risk assessments because HED has identified these two degradates of concern (D230141 and D230656; Oct and Nov 1996). Both degradates are similar in structure to

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### parent pyridaben. These degradates are considered of to be of concern in the ecological risk assessment of pyridaben. However, half-lives calculated for pyrid aben do not differ from halflives calculated for total residues of concern (i.e., pyridaben + PB-7 + PB-9). Thus adding them into the exposure expressi on would not significantly impact the estimated exposure
concentrations.

Available toxicity data for environmental mixtures of pyridaben with other pesticides will be presented as part of the ecological risk assessmen t. It is expected that the toxic effect of pyridaben, in combination with ot her pesticides used in the environment, is likely to be a function of many factors including but not necessarily limited to: (1 ) the exposed sp ecies, (2) the co-contaminants in the mixture, (3) the ratio of pyridaben and co -contaminant concentrations, (4) differences in the pattern and duration of expos ure among contaminants, and (5) the differential effects of other physical/chemical charac teristics of the r eceiving waters ( e.g. organic matter present in sediment and suspended in water). Qu antitatively predicting the combined effects of
all these variables on mixture toxicity to any given taxa with confidence is beyond the capabilities of the available data and methodologies. However, a qualitative discussion of implications of the available pesticide mixture effects data on the confidence of risk assessment conclusions will be addressed as part of the uncertainty analysis.

8.2. Measures of Exposure

In order to estimate risks of pyridaben exposures in aquatic and terres trial environments, all exposure modeling and resulting risk conclusion s will be made based on maximum application rates for the currently registered uses. Measures of exposure are based on aquatic and terrestrial models that predict estimated environmental co ncentrations (EEC) of pyridaben using maximum labeled application rates and appl ication methods that have the gr eatest potential for off-site transport of the chemical. The models used to predict aquatic EECs are the Pesticide Root Zone Model coupled with the EXposure Analysis Modeling System (PRZM/EXAMS). For exposure to sediment dwelling organisms, predicted pore water EECs are generate d using the Pesticide Root Zone Model coupled with the EXposure An alysis Model System (PRZM/EXAMS). If long range transport potential (LRT P) is of concern, The “OECD Pov and LRTP Screening Tool” (version 2.0 4 

### ) will be used in evaluating the overall pe rsistence (Pov), and LRTP of pyridaben. The OECD Tool requires estimated degradation half-lives in so il, water and air, and partition
coefficients between air and wa ter and between octanol and wate r as chemical-specific input parameters to calculate persistence and the metrics of LRTP. The m odel used to predict
terrestrial EECs on food items is T-REX. The model used to deri ve EECs relevant to terrestrial and wetland plants is TerrPlant. These models ar e parameterized using environmental fate data from studies submitted by registrants and from the scientific literature.

PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, April 2005) are simulation models coupled with the graphical user interface, PE (v5.0, Nove mber 2006) to generate daily exposures and 1- in-10-year EECs of pyridaben that may occur in surface water bodies adjacent to application sites receiving pyridaben through runoff and spray drift. PRZM simulates pesticide application,
movement and transformation on an agricultural field and the resultant pesticide loadings to a receiving water body via runoff, erosion, and spra y drift. EXAMS simulates the fate of the

4 Available online at: http://www.oecd.org/document/17/0,3343,en_2649_34373_40754961_1_1_1_1,00.html



### -21 of 62-

### pesticide and resulting concentrations in the water body. The standard watershed geometry used for ecological pesticide assessments assumes app lication to a 10-hectare agricultural field that drains into an adjacent 1-hectare wa ter body that is 2 meters deep (20,000 m 3 

### volume) with no outlet. The composite model PRZM/EXAMS is used to estimate exposure of aquatic organisms to pyridaben at a location that is expected to be more vulnerable than most locations where a specific crop is crown. Therefore, the resulting exposure estimates are expected to be protective of aquatic wildlife in most locations. Measures of exposure for aquatic species include the 1-in10-year peak and 1-in-10-year rolling mean con centrations. The 1-in-10-year peak is used for estimating acute exposures of direct effects to aq uatic 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-year 21-day mean is used for assessing a quatic invertebrate chronic exposure. Appendix E includes a summary of PRZM/EXAMS input parameters as we ll as an example output for applications of pyridaben on pears in Washington.

KABAM v.1.0 is used to estimate potential bioaccu mulation of pyridaben in freshwater aquatic food webs and subsequent risks to mammals and birds via consumption of contaminated aquatic prey. At this time, no tool is available in EF ED to quantify the bioaccumulation potential of pyridaben in terrestrial food webs.

Exposure estimates for terrestrial an imals assumed to be in the target area or in an area exposed to spray drift are derived using the T-RE X model (version 1.4.1, 10/08/2008). This model incorporates the Kenaga nomogr aph, as modified by Fletcher et al. (1994), which is based on a large set of actual field residue data. The uppe r limit values from the nomograph represent high
end residue values from actual field measurem ents (Hoerger and Kena ga, 1972). The Fletcher et al. (1994) modifications to the Kenaga nomograph are based on m easured field residues from 249 published research papers, including informa tion on 118 species of plants, 121 pesticides,
and 17 chemical classes. Given that no suitable data on interception and subsequent dissipation from foliar surfaces is available for pyridaben, th e EFED default foliar di ssipation half-life of 35 days is used based on high-end dissipation values for pesticides reported by Willis and McDowell (1987).

EECs for terrestrial plants inha biting dry and wetland areas are derived using TerrPlant (version 1.2.2, 12/26/2006). This model estimates exposure by calculating residues in runoff and in spray drift. These calculations are solely based upon inputs of solubility, application rate, and minimum incorporation depth.

The AgDRIFT spray drift model (v2.01; May 2001) is used to assess exposures of organisms to pyridaben that is deposited on terr estrial habitats by spray drift.

8.3. Measures of Effect

Ecological effects data are used as measures of di rect and indirect effect s to biological receptors. Data are obtained from registrant-submitted studies or from literature studies identified by ECOTOX. The ECOTOX database provi des more ecological effects data in an attempt to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and wildlife. ECOTOX was

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### 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.

Information on the potential effects of pyridaben on non-target animal s is also collected from the Ecological Incident Information System (EIIS; USEPA 2007 e ). The EIIS is a database containing adverse effect (typic ally mortality) reports on non -target organisms where such
effects have been associated with the use of pesticides. Any new incident reports beyond what have already been discussed in this problem formulation will be reviewed.

Incidents reported in the aggreg ate incident reports and the Av ian Incident Monitoring System (AIMS) will also be searched. AIMS is a da tabase administered by the American Bird Conservancy (it was partially funded by the EPA). It contains publicly av ailable data on reported avian incidents involving pesticides (online at: http://www.abcbirds.org/abcprograms/ policy/pesticides/aims/aims/index.cfm ).

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

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

The acute measures of effect used fo r animals in this assessment are the LD 50 

### , LC 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 test organisms. Endpoints for chronic measures of exposure for listed and non-lis ted animals are the NOAEL/NOAEC and NOEC.
NOAEL stands for “No Observed-Adverse-Effect-Level ” and refers to the hi ghest tested dose of a substance that has been reported to have no ha rmful (adverse) effects on test organisms. The NOAEC ( i.e. , “No-Observed-Adverse-Effect-Concentration” ) is the highest test concentration at
which none of the observed effects were statistically different from the control. The NOEC is the
No-Observed-Effects-Concentration. For non-list ed plants, only acute exposures are assessed ( i.e. , EC 25 

### for terrestrial plants and EC 50 

### for aquatic plants); for lis ted plants either the NOAEC

or EC 05 

### is used.

8.4. Integration of Exposure and Effects

Risk characterization is the integration of e xposure and ecological effe cts characterization to determine the potential ecological risk from the use of pyridaben and the likelihood of direct and indirect effects to non-target organisms in aquatic and terrestrial habitats. The exposure and toxicity effects data are integrated in order to evaluate the risks of a dverse ecological effects on

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### non-target species. For the assessment of pyridaben risks, the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are divide d by acute and chronic toxicity values. The resu lting RQs are then compared to the Agency’s Levels of Concern (LOC) (USEPA, 2004b). These criteria are used to indica te when pyridaben use, as directed on the labels, has the potential to cause adverse direct or indirect eff ects to non-target organisms. In addition, incident data from EIIS, aggregate incide nt reports, and AIMS will be considered as part of the risk characterization.

8.5. Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the deterministic point-estimate based approach described in th e risk assessment. Depending on the risk manager’s need for additional information regarding risk, an effort will be made to further describe risk using probabilistic tools that the Agency has developed. These t ools have been reviewed by FIFRA Scientific Advisory Panels ( http://www.epa.gov/scipoly/sap/index.htm ) and have been deemed as appropriate means of refining assessments wh ere deterministic approaches have identified
risks.

8.6. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to Federally-listed th reatened and/or endangere d (listed) species from registered uses of pyridaben. This assessmen t will be conducted in accordance with the Overview Document (USEPA, 2004b), provisions of the ESA, and the Services’ Endangered Species Consultation Handbook (USFWS/NMFS, 1998).

The action area is used to identify all listed (t hreatened and endangered) species and designated
critical habitat that could be affected by the Federal action. The Federal action is the authorization or registration of pesticide use or uses as descri bed on the label(s) of pesticide products containing a particular active ingredient. The action ar ea is defined by the Endangered Species Act as, “all areas to be affected directly or indirec tly by the Federal action and not merely the immediate are involved in the action” (50 CFR §402.2). Based on an analysis of the Federal action, the action area is defined by the actual and pote ntial use of the pesticide.

In the case of nationwide ecological risk a ssessment conducted for pyridaben under Registration Review, the action area will encomp ass the entire United States and its territories. The purpose of defining the action area as the entire United States and its territories is to ensure that the initial area of consideration encompasses all areas where pyridaben may be used now and in the future, including the potential for off-site trans port via spray drift and downstream dilution. Additionally, the concept of a na tionwide action area takes into acc ount the potential for direct and indirect effects and any poten tial modification to critical ha bitat based on ecological effect measures associated with reduction in survival, growth, and reproduction, as well as the full suite
of sublethal effects available in the effects litera ture. It is important to note that the nationwide action area does not imply that dire ct and/or indirect e ffects and critical ha bitat modification are expected to or are likely to occur over the full ex tent of the action area, but rather to identify all listed species and critical habita t that may potentially be affect ed by the action. The Agency will

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### use more rigorous analysis including consideratio n of available land cover data, toxicity data, and exposure information to determine areas wh ere individual listed species and designated critical habitat may be affected or modified via endpoints associated with reduced survival, growth, or reproduction.

8.7. Drinking Water Assessment

A drinking water assessment will be conducte d to support future human dietary exposure assessments of pyridaben. Concentrations of pyrid aben plus the identified residues of concern (pyridaben + PB-7 + PB-9) in surface wate r will be estimated using PRZM/EXAMS (see description in Section 7.2 ). However, the contribution of th e two residues of concern (PB-7 and PB-9) are expected to have littl e impact on the persistence of the exposure estimates since both of these degradates were formed in minor amounts (<10%) in fate studies ( e.g ., anaerobic soil metabolism) that do not signi ficantly impact the environmental modeling. Ground water exposure estimates for pyridaben plus the resi dues of concern will be estimated using the Screening Concentration in Ground Water (SCI -GROW) model (v.2.3, July 2003) followed by a higher tier model if necessary. It is important to note that com pounds such as pyridaben with K
oc 

### values greater than 9995 ml/g are beyond the scope of the regre ssion data used in SCI-GROW development. Therefore, if ground water contam ination by pyridaben is a concern, the Agency recommends that a higher tier ground water expos ure assessment be considered, regardless of the concentration returned by SCI-GROW. The dr inking water assessment will also include a summary of available surface and ground water monitoring data.

8.8. Preliminary Identification of Data Gaps

8.8.1. Environmental Fate Data

The studies submitted to fulfill environmental fa te data requirements for pyridaben are not sufficient to conduct an exposure assessment; si x requirements have not been met: 1) An acceptable aerobic aquatic metabolism study ha s not been submitted. Conditional data was submitted to the Agency but was classified as una cceptable. This study is necessary in order to describe the fate of pyridaben in surface water bodi es down-gradient from terrestrial use sites. 2) There is only one acceptable aerobic soil metabolism study conducted on one soil. Conditional data was submitted to fulfill this requirement, but the studies were found unacceptable. This study needs to be conducted on at le ast four relevant soils of di fferent organic carbon content, pH, clay content, and microbial biomass in order to begin to understand th e variability in aerobic biodegradation of pyridaben in the environment. 3) Submi ssion of an anaerobic aquatic metabolism study is necessary to understand th e degradation of pyrid aben in oxygen-limiting environments. 4) Submission of a storage stability study is essential in orde r to be confident that any degradation measured in the test system wa s due solely to the environment of that test system, and not due to handling and storage. Lastly, although not necessary for exposure assessment, submission of an environmental chemistry method in water and in soil, as well as associated independent laboratory validations for these methods is also necessary in order to support enforcement and monitoring purposes at the federal, state, and local levels (5 th 

### and 6 th


### data requirements).

-25 of 62-

### Due to the bioaccumulation potential of pyridabe n, EFED is requesting a bioconcentration study with the oyster and an aqua tic food chain transfer study.

Draft Data Call-In (DCI) tables for the requested data are provided in APPENDIX F

. Table 8.1 identifies studies by MRID that offer data fo r each guideline requirement, as well as study
classifications and whether or not further data are needed in order to support risk assessment ( i.e. , whether there is a data gap).

TABLE 8.1. Environmental Fate Da ta Requirement Table for Pyridaben.

OPPTS
Guideline Data Requirement Submitted
Studies (MRID) Classification Data Gap? Comments

835.2120 Hydrolysis 4 2680153 Acceptable No
-- 835.2240 Aqueous photolysi s 43680127 Acceptable No
-- 835.2410 Soil photolysis 43792110 Acceptable No
-- 42680154 Acceptable Only one soil was acceptable.

47576104 Unacceptable 835.4100 Aerobic soil
metabolism

47583301 Unacceptable Yes

835.4200 Anaerobic soil
metabolism 43680128 Acceptable No
--

835.4300 Aerobic aquatic
metabolism 47576105 Unacceptable Yes

835.4400 Anaerobic aquatic
metabolism -- -- Yes No data submitted

42680156 Supplemental

42680155 Supplemental

44008302 Supplemental 835.1230
835.1240 Adsorption/ desorption and leaching

43792111 Supplemental No No additional data needed

43909904 Supplemental Terrestrial field dissipation
43680430 Supplemental No Studies were downgraded since there is no acceptable storage stability study conducted for the longest duration of storage from sampling to analysis.

Confined terrestrial field dissipation 43680429 Supplemental No Not a required study. Provides supplemental data on the dissipation of pyridaben in terrestrial environments. 835.6100

Storage Stability 42680103 Unacceptable Yes Interim study submitted. Need final study conducted for the long est sample storage
duration in the unconfined field dissipation study.
Aquatic Microcosm Study 43792108 Supplemental No Not a required study. Provides supplemental data on the dissipation of pyridaben in aquatic environments. 835.6200

Confined aquatic dissipation 43792112 Supplemental No Not a required study. Provides supplemental data on the dissipation of pyridaben in aquatic environments.

850.1710 Oyster
bioconcentration none Not applicable Yes No data submitted

Supplemental 43792114 Does not fulfill guideline. 850.1730 Fish
bioconcentration Acceptable 43792113 No
Supersedes MRID 43792114



### -26 of 62-OPPTS
Guideline Data Requirement Submitted Classification Data Comments
Studies Gap? (MRID)

850.1850 Aquatic food chain
transfer none Not applicable Yes No data submitted

835.6200 Analytical method
in water -- -- Yes No data submitted

835.6100 Analytical method
in soil -- -- Yes No data submitted



### 8.8.2. Effects Data

Although many submissions have been made to pr ovide data on the effects of pyridaben to aquatic and terrestrial organisms, data gaps still exist ( Tables 8.2-8.4 ). Data gaps include the following: avian acute oral toxic ity for a passerine species, acute toxicity with estuarine/marine fish, estuarine/marine fish early-life stage toxicity, estuarine/marine invertebrate full life cycle toxicity, aquatic vascular and non- vascular plant and terrestrial pl ant toxicity. These data gaps
are discussed below.

TABLE 8.2. Available Ecologi cal Effects Data for Terrestrial Animals Exposed to Pyridaben and Remaining Data Gaps.

Guideline Description MRID Classification Data Gap? Comments

42680105 Acceptable 850.2100 Avian oral toxicity

42680106 Acceptable Yes*

42680107 Acceptable 850.2200 Avian dietary toxicity 42680108 Acceptable No

43792101 Acceptable 850.2300 Avian reproduction

43792102 Acceptable No

850.3020 Honeybee acute contact toxicity 43680423 Acceptable No

850.3030 Honey bee residue on foliage 43680424 Acceptable No

850.3040 Field testing for pollinators none Not applicable Yes** *At this time, EFED is not requesting data to fulfill this data gap.

**These data are required
because data from a residual toxicity study (MRID 43680424) indicates extended residual toxicity.



### Avian acute oral toxicity with a passerine species

According to the 40 CFR 158, acute oral toxicity data are requir ed for a passerine species. Because no acute oral toxicity data have been submitted for a passerine species exposed to pyridaben, this is a data gap. Available acute oral toxicity data for birds (MRIDs 426801-05 and -06) indicate that pyridaben is classified practically non-toxic to birds on an acute oral exposure basis. Therefore, EFED is not requesting oral toxicity data fo r passerines exposed to pyridaben.
It should be noted that no acute oral toxicity data for passerines exposed to pyridaben have been identified in the scientific literature (using ECOTOX) and no ecological in cidents involving birds exposed to pyridaben have b een identified (using EIIS).

-27 of 62-

### Field testing for pollinators

According to 40 CFR Part 158, this study is requir ed if any of the following are met: 1) data from other sources (Experimental Use Permit program, university research, registrant submittals,

etc .) indicate potenti al adverse effects on colonies, especial ly effects other than acute mortality (reproductive, behavioral, etc .); 2) data from residual toxici ty studies indicat e extended residual toxicity; or 3) data derived fr om studies with terrestrial arth ropods other than bees indicate potential chronic, reproductive or behavioral effects. In a foliar residue study MRID (43680424), pyridaben residues aged 24 h caused mortality (> 20%) in honey bees. Therefore, the second
condition relevant to this data re quirement is met and submission of a field study of the effects of pyridaben on pollinators is required (Guidelin e 850.3040). Pyridaben registrants must submit a study protocol for review by the Agency prior to initiation of the field testing for pollinators study.

TABLE 8.3. Available Ecological Effects Data for Aquatic Animals Exposed to Pyridaben and Remaining Data Gaps.

Guideline Description MRID Classification Data Gap? Comments

42680109 Acceptable

42680110 Acceptable

43680401 Acceptable

43680402 Acceptable 850.1075 Freshwater fish – Acute toxicity

43680403 Supplemental No

850.1075 Saltwater fish – Acute toxicity 43680406 Supplemental Yes

43680404 Acceptable 850.1010 Freshwater invertebrates – Acute toxicity 42680111 Acceptable No

43680405 Acceptable 850.1025
850.1035
850.1045
850.1055 Saltwater invertebrates – Acute toxicity * 43680407 Supplemental No

43680408 Acceptable 850.1300 Freshwater invertebrate – life cycle test 43680410 Supplemental No

850.1350 Saltwater invertebrates – life cycle test 43680409 Supplemental Yes

850.1400 Freshwater fish – early life stage test none Not applicable No**

850.1400 Saltwater fish – early life stage test Not available Not applicable Yes

850.1500 Freshwater fish - lifecycle 43792106 Acceptable No

850.1735 Whole sediment: acute
freshwater invertebrates Not available Not applicable Yes

none Whole sediment: chronic
freshwater invertebrates Not available Not applicable Yes *Data are required for
one estuarine/marine
mollusk and one
estuarine/marine
invertebrate. These data
are submitted for
Guidelines 850.1025 (MRID 43680407) and 850.1035 (MRID 43680405), respectively.
No data have been
submitted under
850.1045 and 850.1055.

**Chronic toxicity data
for a freshwater fish are
available from a full life cycle study.



### -28 of 62-

### Acute toxicity to es tuarine/marine fish

Acute toxicity data are available for sheepshead minnow exposed to pyridaben ( Cyprinodon variegates ; MRID 43680406). This study was classified su pplemental because the highest test concentration resulted in 50% mortality, l eading to uncertainty in the established LC 50



### . Submission of acceptable acute toxi city data for estuarine/marine fish (guideline 850.1075) will reduce uncertainty associated with the acute endpoint and increase confidence in risk
conclusions.

Chronic toxicity to estuarine/marine fish

Chronic toxicity data are not available for es tuarine/marine fish. The updated Part 158 data requirements, specify that an early life-stage st udy is required for estu arine/marine fish for chemicals that have the potential to enter estuarine/marine water. In addition, these data may be required when the acute LC 50 

### for an estuarine/marine fish is <1 mg/L, and when reproductive effects are observed in other aquatic organisms. Because pyridaben use sites may overlap with
watersheds of estuarine/marine environmen ts, pyridaben has the potential to enter estuarine/marine environments. In addition, the LC 50 

### for sheepshead minnow exposed to pyridaben is <1 mg/L (MRID 43680406) and repr oductive effects have been observed in freshwater fish (MRID 43792106) and inve rtebrates (MRIDs 43680408 and 43680410) exposed to pyridaben. Therefore, an early life stage test (guideline 850.1400) is required for pyridaben.

Chronic toxicity to estuarine/marine invertebrate

Supplemental chronic toxicity data are available for mysid shrimp exposed to pyridaben (43680409). This study was classified supplemental due to poor cont rol performance and lack of observed effects at any treatment level. Subm ission of acceptable chroni c toxicity data for estuarine/marine invertebrates (Guideline 850.1350) will reduce uncertainty associated with the chronic endpoint that is currently available a nd will increase confidence in risk conclusions.

Whole sediment toxicity to freshwater invertebrates

No data are currently available to characterize the acute or chronic toxicity of pyridaben to sediment dwelling invertebrates. The updated Pa rt 158 data requirements, published in October 2007, specify that acute and chroni c toxicity data for sediment invertebrates are conditionally required if the half-life of th e pesticide in sediment >10 da ys in aerobic soil or aquatic
metabolism studies and if any of the following conditions exist: a) the K d 

### is ≥ 50; b) the log K
ow 

### is ≥ 3 or c) the K
oc 

### is ≥ 1000. Since the half-live of pyridaben in soil under aerobic conditions is >10 days, the Log K
ow 

### is >3 and the K
oc 

### is >1000, acute and chronic t oxicity data for one species of sediment-dwelling invertebra te are required for pyridaben. Pyridaben registrants must submit a study protocol for revi ew by the Agency prior to init iation of the chronic toxicity study with sediment dwelling invertebrates.

-29 of 62-

### TABLE 8.4. Available Ecologi cal Effects Data for Plants Exposed to Pyridaben and Remaining Data Gaps.

Guideline Description MRID Classification Data Gap? Comments

850.4100 Terrestrial Plant toxicity: seedling emergence (Tier 1) 43680419 Supplemental Yes

850.4150 Terrestrial Plant toxicity: vegetative vigor (Tier 1) 43680420 Acceptable* Yes

43680422 Supplemental 850.5400 Aquatic Plant Growth: algae (Tiers 1 and 2) 43680421 Supplemental Yes **

850.4400 Aquatic Plant Growth: vascular plants (Tier 1) 43680422 Supplemental Yes ** *Although this study is classified acceptable, it was
conducted with TGAI.
Because no data are
available from studies conducted with a typical end use product, this guideline is not fulfilled.

**Although Tier 1 studies
are available for 1vascular and 4 non-vascular aquatic plants, these studies did not test up to the limit concentration of 100 mg/L.



### Terrestrial plants: seedling em ergence and vegetative vigor

Tier 1 data were submitted for seedling emergence and vegetative vigor studies were plants were exposed to 0.5 lb a.i./A techni cal pyridaben. There are two uses of pyridaben (SLN on Pears and ornamentals) that have single ap plication rates that exceed 0.5 lb a.i./A. In addition, the 40 CFR158 requires that Tier I seedling emergence and vegetative vigor te sts are conducted with typical end use product. Theref ore, guidelines 850.4100 and 850.4150 ar e data gaps. In order to fulfill these guidelines, additional Tier 1 seedling emergence and vegetative vigor studies are required. These studies must be co nducted at the highest single application rate for pyridaben (1.0 lbs a.i./A on ornamentals) and with a typi cal end use product contai ning pyridaben. If the Tier I data result in significant decreases in endp oints compared to controls or >25% effects to any test species, Tier II data should be submitted for that species.

Aquatic Plant Growth: algae

Supplemental Tier I data are available for four species of algae exposed to <20 μg a.i./L pyridaben (MIRD 43680422). In addition, a suppleme ntal Tier II study is available for green algae exposed to pyridaben (MRID 43680421). In or der to fulfill the guide line requirement for algae, additional Tier I data must be submitted for four species of algae exposed to pyridaben at a concentration of 100 mg a.i. /L (limit test). If the Tier I data result in >50% effects to any test species, Tier II data should be submitted for that species.

Aquatic Plant Growth: vascular plants

Supplemental Tier I data are available for duckw eed exposed to <20 μg a.i./L pyridaben (MIRD 43680422). In order to fulfill the gui deline requirement for aquatic vascular plants, additional Tier I data must be submitted for a vascular aquatic plant ( i.e. , duckweed) exposed to pyridaben

-30 of 62-

### at a concentration of 100 mg a.i./L (limit test). If the Tier I data re sult in >50% effects to the test species, Tier II data should be submitted for that species.

-31 of 62-

### 9. References

9.1. Scientific Literature and Government Publications

Armitage, J.M. and F.A.P.C. Gobas. 2007. A terrestrial food-chain bioaccumulation model for POPs. Environmental Science and Technology, 41 (11): 4019-4025.

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

Hoerger, F. and E. E. Kenaga. 1972. Pesticide Residues on Plants: Correlation of Representative Data as a Basis for Estimation of their Magnitude in the Environment. In F. Coulston and F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and Technology, Georg Thieme Publ., Stuttgart, West Germany, pp. 9-28.

Hollingworth, R.M., K.I. Ahammadsahib, G. Gadelhak, J.L. McLaughlin. 1994. New inhibitors of Complex I in the
mitochondria1 electron transfer ch ain with activities as pesticides. Biochem. Soc. Trans. 22,23 0 23 3.

Kelly, B.C. and F.A.P.C. Gobas. 2003. An Arctic terres trial food-chain bioaccumulation model for persistent organic pollutants. Environmental Science and Technology, 37(13): 2966-2974.

Kelly, B.C.; Ikonomou, M.G.; Blair, J.D.; Morin, A.E. and F.A.P.C. Gobas. 2007. Food web-specific biomagnifications of persistent organic pollutants. Science, 317: 236.

USEPA. 1998. Guidelines for Ecological Risk Assessment. EPA/630/R-95/002F. Risk Assessment Forum, Office of Research and Development, Washington, D.C. April 1998. Online at: http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=12460

USEPA. 1999a. Tier I Estimated Environmental Concentrations of Pyridaben in Drinking Water for Tolerance Petition for the use on Cranberry (DP 258903). USEPA/OPP/EFED, Washington, DC 20460.

USEPA. 1999b. Tier II Drinking Water EECs for Use in the Human Health Risk Assessment (DP 259315). USEPA/OPP/EFED, Washington, DC 20460.

USEPA. 2004a. Drinking Water Exposure Screening Assessme nt for Proposed Uses of Pyridaben on Strawberries, Hops, Tropical Fruit and Stone Fruit. USEPA/OPP/EFED, Washington, DC 20460.

USEPA. 2004b. Overview of the Ecological Risk Assessm ent Process in the Office of Pesticide Programs. U.S. Environmental Protection Agency, Of fice of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004.

USEPA. 2006. Standardized Soil Mobility Classifica tion Guidance. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances , Office of Pesticide Programs, Environmental Fate and Effects Division, Memorandum. Apr. 21, 2006.

USEPA. 2008. White paper on methods for assessing ecologi cal risks of pesticides with persistent, bioaccumulative
and toxic characteristics. Submitted to the FIFRA Sc ientific Advisory Panel for review and comment. United States Environmental Protection Agency, Envi ronmental Fate and Effects Division. Available
online at: http://www.epa.gov/scipoly/sap/meetings/2008/oc tober/sap_pbt_whitepaper_final_Oct_7_08d.pdf.

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



### -32 of 62-

### 9.2. Submitted Environmental Fate an d Product Chemistry Studies

42676103 Sato, T. (1993) Physical and Chemical Character istics of Pyridaben (NC-129) Acaricide and Insecticide Technical Grade Active Ingredient and Manufact uring-use Product: Lab Project Number NCI-129- H506. Unpublished study prepared by Battelle, Ricerca, Inc., and Chemicals Inspection & Testing Inst. 402 p.

42680153 O'Connor, J. (1992) NC-129: Determination of Hydrolysis as a Function of pH: Final Report: Lab Project Number: 92/NAS106/0374: 92/11493. Unpublished study prepared by Life Science Research, Ltd. 131 p.

43680427 O'Connor, J. (1995) NC-129: Photodegradation in Water: Final Report: Lab Project Number: 94/11765: 94/0160: 94/NAS101/0160. Unpublished study prepared by Pharmaco LSR Ltd. 304 p.

43792110 O'Connor, J. (1995) NC-129: Photodegradation on Soil: Final Report: Lab Project Number: 94/0044: 94/11766: NAS/102. Unpublished study prepared by Pharmaco-LSR Ltd. 331 p.

42680154 O'Connor, J. (1993) NC-129: A Study of Aerobic Soil Metabolism: Lab Project Number: NAS/099/NC129: 92/NAS099/0211: 93/10100. Unpublished study prepared by Life Science Research, Ltd. 541 p.

47576104 Crowe, A. (2002) Pyridaben - Aerobic Soil Metabolism (Route of Degradation). Project Number: NAS/341. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 99 p.

43680428 O'Connor, J. (1994) NC-129--A Study of Anaerobic Metabolism plus First Amendment: Final Report: Lab Project Number: 94/10947: 94/NAS103/0285: 93/NAS103/0546. Unpublished study prepared by Pharmaco LSR Ltd. 412 p.

42680155 O'Connor, J. (1992) NC-129: Determination of Soil Adsorption/Desorption Properties: Lab Project Number: LSR 92/0172: 92/11152. Unpublished study prepared by Life Science Research, Ltd. 202 p.

42680156 O'Connor, J. (1993) NC-129: Determination of the Mobility of NC-129 and Its Degradates by Soil Column Studies: Lab Project Number: NAS/105/NC-129: 92/NAS105/0215: 93/10099. Unpublished study prepared by Life Science Research, Ltd. 415 p.

43360701 Winkler, V. (1994) BASF Response to EPA Revi ew of NC-129: Determination of the Mobility of NC129 and its Degradates by Soil Column Studies: Lab Project Number: 94/5110: LSR 92/NAS 105/0215: 93/10099. Unpublished study prepared by BASF Corp. 53 p.

43792111 O'Connor, J. (1995) NC-129: Determination of the Mobility of NC-129 and its Degradates by Soil Column Studies: Amended Final Report: Lab Pr oject Number: 94/1164: 94/11764: NAS/105. Unpublished study prepared by Pharmaco LSR Ltd. 431 p.

44008302 Morgan, P. (1996) P-14: Determination of the Adsorption/Desorption Properties in Soils: Final Report: Lab Project Number: NAS/176: 95/NAS176/1199: 96/5038. Unpublished study prepared by Huntingdon Life Sciences Ltd. 51 p.

43680429 Venkatesh, K. (1995) Confined Terrestrial Field Dissipation of (carbon 14)-BAS 300 I: Lab Project Number: 95/5012: M9019: M9317. Unpublished study prepared by BASF Corp. and Agvise Labs. 100

p.

43680430 Clark, J.; Jackson, S.; Qiu, J. (1995) Pyridabe n Soil Dissipation in Citrus Groves: Lab Project Number: 95/5052: 93002: ER 95004. Unpublished study prepared by Grayson Research Ltd. 1322 p.

43792112 Singh, M. (1995) Confined Aquatic Dissipation of Pyridaben (BAS 300 I) in a Simulated Microcosm Environment: Lab Project Number: 95/5020: 93013: M9418. Unpublished study prepared by Toxicon Environmental Sciences and BASF Corp. 177 p.

43909904 Clark, J.; Jackson, S.; Qiu, J. (1995) Pyridaben Soil Dissipation in Apple Orchards in the USA: Through



### -33 of 62-180 Days: Summary Report: Lab Project Number: RCN 94164: RCN 94165: 95/5178. Unpublished study prepared by Grayson Research , Ltd.; ACDS Research, Inc.; and Qualls Agricultural Labs. 892 p.

43680432 Singh, M. (1994) Dissipation of (Carbon 14)-BAS 300 I in an Outdoor Confined Aquatic Ecosystem: Lab Project Nos. 94/5182; 91118; M9316. Unpublished study prepared by BASF Corp. and Wildlife International Ltd. 134 p.

43680433 Smith, M. (1995) HPLC Method for Residue Dete rminations of Pyridaben (BAS 300 I) Metabolite, P-16 in Pond Water, Sediment, and Soil: Lab Project Number: 95/5011: D9307: 93065. Unpublished study prepared by BASF Corp. 65 p.

43792113 Jenkins, W. (1994) NC-129: Determination of its Accumulation in the Rainbow Trout Under FlowThrough Exposure Conditions: (Final Report): Lab Project Number: 94/10081: 93/NAS087: 93/NAS088. Unpublished study prepared by Pharmaco:LSR, Ltd. 376 p.

43792114 Ohuchiyama, N. (1987) Test on Bioaccumulation of NC-129 in Carp: Test Number: 6208: Final Report: Lab Project Number: 88/0573. Unpublished study prepared by Kyushu Lab. 60 p.



### 9.3. Submitted Effects Studies

42680105 Grimes, J.; Jaber, M. (1986) The Acute Oral To xicity with the Mallard (NC-129): Final Report: Lab Project Number: 221-102: 88/0600. Unpublished study prepared by Wildlife International, Ltd. 23 p.

42680106 Grimes, J.; Jaber, M. (1986) NC-129: An Acute Oral Toxicity Study with the Bobwhite: Final Report: Lab Project Number: 221-101: 88/0598. Unpublished study prepared by Wildlife International, Ltd. 21 p.

42680107 Grimes, J.; Jaber, M. (1987) NC-129: A Dietary LC50 Study with the Mallard: Final Report: Lab Project Number: 221-106: 88/0601. Unpublished study prepared by Wildlife International, Ltd. 25 p.

42680108 Grimes, J.; Hinken, C.; Jaber M. (1986) NC-129: A Dietary LC50 Study with the Bobwhite: Final Report: Lab Project Number: 221-105: 88/0599. Unpublished study prepared by Wildlife International, Ltd. 24 p

42680109 Willis, C.; Wilson, I. (1987) The Acute Toxicity of NC-129 to Rainbow Trout: Final Report: Lab Project Number: AFT/86/022B: 88/0596. Unpublished study prepared by Aquatox, Ltd. 40 p.

42680110 Willis, C. (1988) The Acute Toxicity of NC-129 to Bluegill Sunfish: Final Report: Lab Project Number: LSR/87/NAS021/600: 87/NAS021/600: 88/0595. Unpublished study prepared by Life Science Research, Ltd. 51 p.

42680111 Willis, C.; Wilson, I. (1987) The Acute Toxicity of NC-129 to Daphnia Magna: Final Report: Lab Project Number: AFT/86/024: 88/0594. Unpublished study prepared by Aquatox, Ltd. 35 p.

42680119 Yanagita, T. (1990) Acute Toxicity Study by Oral Administration of NC-129 in Rats: Lab Project Number: ML-303F: 90/0585. Unpublished study prepared by Preclinical Research Laboratories Central Institute for Experimental Animals. 102 p.

42680120 Yanagita, T. (1990) Acute Toxicity Study by Oral Administration of NC-129 in Mice: Lab Project Number: ML-303E: 90/0586. Unpublished study prepared by Preclinical Research Laboratories Central Institute for Experimental Animals. 94 p

42680143 Tesh, J. et al. (1989) NC-129: Effects of Dietary Administration upon Reproductive Performance in the Rat: Dose Range-Finding Study: Lab Project Number: LSR 88/0025: 88/0025: 89/0372. Unpublished study prepared by Life Science Research. 94 p.



### -34 of 62-42680144 Willoughby, C. (1990) NC-129: Reproductive Perf ormance Study in Rats Treated Continuously through Two Successive Generations--Volumes I and II: Lab Project Number: LSR 89/NAS033/0937: 89/NAS033/0937: 89/0937: 90/0046. Unpublished study prepared by Life Science Research. 724 p.

43680401 Ward, G. (1994) Pyridaben Technical: Acute Toxi city to Bluegill, Lepomis macrochirus, Under FlowThrough Conditions: Lab Project Number: 94/5002: 93062: ER93046. Unpublished study prepared by Toxikon Environmental Sciences. 33 p.

43680402 Ward, G. (1994) Pyridaben Technical: Acute Toxicity to Rainbow Trout, Oncorhynchus mykiss, Under Flow- Through Conditions: Lab Project Number: 94/5001: 93142: ER93047. Unpublished study prepared by Toxikon Environmental Sciences. 33 p.

43680403 Bootman, J.; Jenkins, W.; O'Connor, J. (1989) NC-129: 21-Day Rainbow Trout Toxicity Study Under Flow-Through Conditions: Lab Project Number: 89/0258: 88/NAS041/0824: 88/0824. Unpublished study prepared by Life Sciences Research Ltd. 41 p.

43680404 Graves, W.; Swigert, J. (1993) Pyridaben Technical A.I.: A 48-Hour Flow-Through Acute Toxicity Test with the Cladoceran (Daphnia magna): Lab Project Number: 93/5169: ER 93057: 92076. Unpublished study prepared by Wildlife International Ltd. 45 p.

43680405 Morrow, J. (1993) Pyridaben (BAS 300 I-Tech. A.I.): Acute Toxicity to the Mysid, Mysidopsis bahia, Under Flow-Through Test Conditions: Lab Project Number: 93/5171: 92017: ER93039. Unpublished study prepared by Toxikon Environmental Sciences. 36 p.

43680406 Morrow, J.; Ward, G. (1993) Pyridaben Technical: Acute Toxicity to the Sheepshead Minnow, Cyprinodon variegatus, Under Flow-Through Test Conditions: Lab Project Number: 93/5155: 92018: ER93058. Unpublished study prepared by Toxikon Environmental Sciences. 33 p.

43680407 Ward, G. (1994) Pyridaben (BAS 300 I-Tech. A.I.): Acute Effect on New Shell Growth of the Eastern Oyster, Crassostrea virginica: Lab Project Number: 94/5024: 93074: ER93048. Unpublished study prepared by Toxikon Environmental Sciences. 44 p.

43680408 Drottar, K.; Swigert, J. (1994) (Carbon 14)-Pyridaben: A Flow-Through Life Cycle Toxicity Test with the Cladoceran, Daphnia magna: Lab Project Number: 94/5074: 93063: ER 94001. Unpublished study prepared by Wildlife International Ltd. 61 p.

43680409 Holmes, C.; Machado, M. (1995) (Carbon 14)Pyridaben (BAS 300 I) Technical--Chronic Toxicity to Mysids (Mysidopsis bahia) Under Fl ow-Through Conditions: Final Report: Lab Project Number: 95/5018: 93033: ER95001.Unpublished study prepared by Springborn Labs, Inc. 180 p.

43680410 Jenkins, W.; Jenkins, C.; O'Connor, J. (1989) NC-129: 21-Day Juvenile Production Study Using Daphnia magna Under Semi-Static Test Conditions: Lab Project Numb er: 89/0271: 88/0700. Unpublished study prepared by Life Science Research Ltd. 45 p.

43680419 Elliott, D. (1992) Tier 1 Seed Germination/Seedling Emergence Nontarget Phytotoxicity Study Using Pyridaben (BAS 300 I-Tech. a.i.): Lab Project Number: 92/5161: 92013: ER92041. Unpublished study prepared by Pan- Agricultural Labs, Inc. 93 p.

43680420 Blackburn, R. (1992) Tier 1 Vegetative Vigor Nontarget Phytotoxicity Study Using Pyridaben (BAS 300 I-Tech. a.i.): Lab Project Number: 92/5160: 92012: ER92040. Unpublished study prepared by Pan-Agricultural Labs, Inc. 70 p.

43680421 Jenkins, W. (1988) Determination of the EC50 of NC-129 to Selenastrum capricornutum Under NonAxenic Conditions: Lab Project Number: 88/0597: 87/NAS027/897. Unpublished study prepared by Life Science Research Ltd. 46 p.



### -35 of 62-43680422 Hughes, J.; Jackson, S. (1994) Tier 1 Non-Target Aquatic Plant Toxicity Study on BAS 300..I (Pyridaben): Lab Project Number: 95/5064: 93008: ER 93034. Unpublished study prepared by Malcolm Pirnie, Inc. and Huntingdon Analytical Services. 106 p.

43792101 Beavers, J.; Sipler, O.; Mitchell, L. et al. (1994) Pyridaben Technical (NC 129): A Reproduction Study with the Mallard: Lab Project Number: 94/10237: 147-159: 72W0021/929008. Unpublished study prepared by Wildlife International Ltd. and BASF Corp. 208 p.

43792102 Beavers, J.; Sipler, O.; Mitchell, L.; et al. (1994) Pyridaben Technical (NC 129): A Reproduction Study with the Northern Bobwhite: Lab Project Number: 94/10238: 147-158: 71W0021/929019. Unpublished study prepared by Wildlife Internationa l, Ltd. and BASF Corp. 206 p.

43792103 Motohashi, F.; Sakamoto, S. (1991) Acute Toxicity Study of 20% WP-Formulation of NC-129 to FreshWater Fish Under Paddy Field Condition: (The First Test): Lab Project Number: 91-504. Unpublished study prepared by Nissan Chemical Industries Ltd.'s Shirao ka Research Station of Bi ological Science. 35 p.

43792104 Motohashi, F.; Sakamoto, S. (1991) Acute Toxicity Study of 20% SC-Formulation of NC-129 to FreshWater Fish Under Paddy Field Condition: (The Second Test): Lab Project Number: 91-519: 91/11266. Unpublished study prepared by Nissan Chemical Industries Ltd.'s Shiraoka Research Station of Biological Science. 36 p.

43792105 Motohashi, F.; Sakamoto, S. (1991) Acute Toxicity Study of 20% WP-Formulation of NC-129 to FreshWater Fish Under Paddy Field Condition: (The Third Test): Lab Project Number: 91-527: 91/11267. Unpublished study prepared by Nissan Chemical Industries Ltd.'s Shiraoka Research Station of Biological Science. 36 p.

43792106 Rhodes, J.; Leak, T.; Holmes, C. (1995) Full Li fe-Cycle Toxicity of BAS 300 I (Pyridaben) to the Fathead Minnow (Pimephales promelas) Under Flow-Thr ough Conditions: Lab Project Number: 40571: 92160: ER94070. Unpublished study prepared by ABC Labs, Inc. and BASF Corp. 1310 p.

43792107 Springer, T.; Jackson, B.; Reed, C. et al. (1994) Acute Toxicity (96 Hour LC 50) of BAS 300 11 I to Bluegill Sunfish in Outdoor Studies: Lab Project Number: 94/5181: 147-146: 91096. Unpublished study prepared by Wildlife International Ltd. and BASF Corp. 114 p.

43792108 Rand, G.; Holmes, C. (1995) Pyridaben (BAS 300 11 I): An Outdoor Aquatic Microcosm Study: Lab Project Number: ER 94066: 92077: J9203004. Unpublished study prepared by Toxikon Environmental Sciences; Huntingdon Analytical Services; an d A & L Midwest Labs, Inc. 677 p.

44039601 Cunningham, F. (1996) Pyridaben: An Outdoor 96-Hour Static Acute Toxicity Test with the Saltwater Mysid, (Mysidopsis bahia): Lab Project Number: J9509002: 96/5075: J9509002/BASF 95121. Unpublished study prepared by Toxikon Environmental Sciences. 202 p.



### -36 of 62-

## APPENDIX A: Current Re gistrations for Pyridaben

Section 3 registrations for formulated products:

7969-106

7969-125

7969-202

7969-225

81880-3

81880-4

81880-5

81880-6

Section 3 registrations for technical pyridaben:

7969-110

7969-164

33906-16 Special local needs registrations for pyridaben:

AZ070009

ME080001
MN080010
PA070003
TX070009
WA090017

-37 of 62-

## APPENDIX B: Characterization of En vironmental Fate Data for Pyridaben

B.1. Transport and Mobility

Pyridaben (2-tert-butyl-5-(4-tert-butylbenzylt hio)-4-chloropyridazin- 3(2H)-one) is a white, crystalline solid that has a melting point of 108-110oC (MRID 42676103). It has a low solubility in water (0.012 ppm @ 20oC ; MRID 42676103). Based on a low vapor pressure 8.21 x 10 -5 

### torr (25oC; MRID 42676103) and Henr y’s Law Constant 6.84 x 10 -3 

### atm·m 3 

### /mole (estimated, EpiSuite v4.0), pyridaben has the potential to volatilize from trea ted sites; however, due to the compound’s high propensity to bind to soil particle s it, it is unlikely that it will volatilize.

Due to pyridaben’s low solubility, low va por pressure, and high level of binding (K ads 

### = 108- 6600; MRID 42680155), it is likely that the chem ical would remain bound to the soils during runoff events. According to the FAO soil mobility classification scheme, pyridaben is hardly mobile (K
oc 

### > 10,000; USEPA, 2006). Therefore, it w ould reach adjacent bodies of water when the runoff events are accompanied by erosion. Py ridaben is unlikely to leach to ground water.

B.2. Bioaccumulation

Based on pyridaben’s Log Kow (6.37; MRID 42676103) , bioaccumulation in aquatic ecosystems is potentially a concern.

Bioconcentration data are available from two sepa rate laboratory studies involving rainbow trout (MRID 43792113). These studies were conducted according to similar methods, but are distinguished by the position of th e radiolabels on the pyridaben molecule. After 28 days of exposure to pyridaben (0.11 μg a.i./L), whole fish BCF values (based on to tal radioactivity) were 342 and 439 (μg/kg-ww per μg/L). In a life cycle test with fathead minnows ( Pimephales promelas ), BCF values ranged 1168 to 3780 in larval and adult fish exposed to pyridaben (MRID 43792106).

In the BCF studies with rainbow trout, the rate constant for the depur ation phase of the two experiments was 0.18 d -1 

### (k T 

### ). Metabolites were identified in th e fish tissue; however, their levels were not quantified. Identified metabolites included: PB-5, PB-7, PB-9, PB-10, PB-11, PB-12 and PB-13 (illustrated below in Table A1). The presence of these metabolites indicate that metabolism of pyridaben may alter the bio accumulation potential of pyridaben through
transformation.

Differences in BCF values observed in the 30-d rainbow trout and full life cycle fathead minnow tests may be attributed to the durations of the studies. Based on the Kow of pyridaben, the time required to reach steady state may be great er than 30 days, which would result in
underestimation of BCF values obtained from the rainbow trout studies. For this reason, KABAM was run to estimate BCF values considering metabolism and steady state conditions.

Using a Log Kow value of 6.37, KABAM (v.1.0) estimates a fish BCF of 1.1x10 5 

### for pyridaben. This value assumes no metabolism of the parent compound. The sum of the loss rate constants for KABAM ( i.e. , k 2 

### , k E 

### and k G 

### ) is 0.012 d -1 

### , which is an order of magnitude lower than the k T



### -38 of 62-

### value estimated from the laboratory BCF studies. A metabolism rate constant can be estimated by subtracting the estimated loss rate constants for respiration, fecal el imination and growth dilution from the empirical k T 

### from MRID 43792113. The result is an estimated k M 

### = 0.17, which indicates that metabolism is likely th e dominant elimination pathway for pyridaben, leading to much lower bioconcentration of to tal pyridaben residues than expected when considering the Kow of pyridaben. When k M 

### is considered, the estimated BCF for a 3.6 g fish (similar to the weight of the test fish in the laboratory BCF studies ) is 5740. This revised estimated BCF is 2 orders of magnitude lo wer than the estimated BCF that assumes no metabolism. Although this estimated value is 1 order of magnitude above the empirical BCF values from the rainbow trout studies (342 and 43 9), it is consistent with the maximum BCF for fathead minnows (3780) reported by the full life cycle study authors.

B.3. Degradation

It appears that photolysis consti tutes the major degradation pathwa y for pyridaben in water (t 1⁄2 = 5 minutes; MRID 43680427). Aerobic soil metabolism is expected to play a minor role in the degradation of the chemical (t 1⁄2 = 110 days; MRID 42680154). Pyridaben degrades to numerous minor degradates (Table B1), at re latively low levels; no major organic degradates (>10% of the applied) were observed, except for B-3 identified in the definitive aqueous photolysis study. Pyridaben is stable to hydr olysis at pH 5, 7 and 9 (MRID 42680153) and is
stable in soil under anae robic conditions (MRID 43680128).

Based on results of a soil photolysis study (MRID 43792110), pyridaben appears to have a biphasic degradation profile (quickly at the begi nning, likely due to soil photolysis, and more slowly afterwards). The initial half-life of pyridaben on soils e xposed to a xenon arc lamp was 11 days. Multiple degradates, at <10% of the applie d were formed. It appear s that the soil photolysis
could enhance the aerobic soil metabolism as evid enced by the formation of additional levels of

C0 2 

### , as compared to the control (unexposed samples).

In an aerobic soil metabolism study (MRID 42680154), pyridaben degraded slowly, with a registrant calculated half-life of 86 days (review er calculated half-life of 110 days) in sandy loam soil (only one soil, CA sandy loam, was accep table; MRID 42680154). Only minor non-volatile degradates were identified. Among them, the follo wing were identified: PB-4, PB-7, and PB-14, as well as other unidentified compounds and CO 2



### .

Evidence suggests that anaerobic soil metabolism does not constitute an important route of degradation for pyridaben. Anaerobic soil metabo lism studies were conducted on two soils: a Florida sand soil, and a California sandy lo am soil (MRID 43680128). The study started with
incubation of the soils under aerobic conditi ons, followed by establishment of anaerobic conditions by maintaining a nitrogen atmosphere. As a result of the esta blishment of anaerobic conditions the degradation of pyridaben essent ially ceased. In addition, the release of C0 2 

### decreased substantially and ultimately ceased. Multiple degradates were observed throughout, the study at < 8% of the applied, including PB-4, PB- 14, PB-5, PB-9, PB-11, B-I, B-3, and B-7.

-39 of 62-

### Table B.1. Pyridaben and Its Radiolabeled Degradates

Common

Name Chemical Name Chemical Structure Study Type Maximum
%AR A (day)

Parent

Pyridaben 2-tert-butyl-5-(4-tertbutylbenzylthio)-4- chloropyridazin-3(2H)-one N

N CH 3 CH 3

CH 3 O

S Cl

C

H 2 CH 3

CH 3

CH 3 -- --

Major Radiolabeled Degradates (>10% AR)

B-3 Unknown Unknown Aqueous Photolysis 20% (30 min)

CO 2 Carbon dioxide C O O

Minor Radiolabeled Degradates

PB-4 2-tert-butyl-5-(4-tertbutylbenzylsulfinyl)-4- chloropyridazin-3(2H)-one N

N CH 3 CH 3

CH 3 O

S Cl

O C H 2 CH 3

CH 3 CH 3 Aerobic Soil Metabolism

Anaerobic Soil Metabolism < 10% (2 months)

<8%

PB-5 5-(4-tert-Butylbenzylthio)- 4-chloropyridazin-3(2H)-

one Anaerobic Soil Metabolism
Fish Bioaccumulation <8%

PB-7 2-tert-butyl-5-[4-(1- carboxy-1- methylethyl)benzylthio]-3- chloro-pyridazin-3(2H)-one N

N CH 3 CH 3

CH 3 O

S Cl

C

H 2 CH 3

CH 3 O

OH Aerobic Soil Metabolism

Anaerobic Soil Metabolism
Fish Bioaccumulation < 10% (2 months)

< 8%

PB-9 2-tert-Butyl-4-chloro-5-[4- (1,1-dimethyl-2- hydroxyethyl)benzylthio]py ridazin-3(2H)-one N

N CH 3 CH 3

CH 3 O

S Cl

C

H 2 CH 3

CH 3 H2

OH Anaerobic Soil Metabolism <8%

PB-11 5-(4-tert-Butylbenzylthio)- 4-chloro-2-(1,1-dimethyl-2-

hydroxyethyl)-pyridazin3(2H)-one Anaerobic Soil Metabolism <8%



### -40 of 62-Common Maximum Chemical Name Chemical Structure Study Type Name %AR A (day)

PB-12 5-(4-tert-Buthylbenzylthio)- 2-(1-carboxy-1- methylethyl)-4- chloropyridazin-3(2H)-one Fish Bioaccumulation

PB-14 2-tert-Butyl-4-chloropyridazin-3(2H)one5-sulphonic acid. N

N CH 3 CH

3

CH 3 O

S O 3 H Cl Aerobic Soil Metabolism

Aqueous Photolysis < 10% (6 months) 7% (6 hours)

PB-16 4-Chloropyridazin-3-(2H)-
one-5-sulfonic acid. NH

N O

S O 3 H Cl Aqueous Photolysis 5% (4-6 hours)

B-1 Unknown Unknown
--

B-7 2-(4-Carboxyphenyl)-2- methylpropionic acid CH 3

CH 3 O

OH O

OH --

A. %AR means “percent of applied radioactivity”.



### B.4. Field Dissipation

Four terrestrial field dissipati on studies were conducted to suppor t the registration of pyridaben, two in apple orchards, and two in citrus groves. For the orchard studies pyridaben was applied
twice at 0.6 lbs a.i./A with an application inte rval of 30 days (MRID 43909904), and for the citrus grove study pyridaben was a pplied twice at 0.5 lbs a. i./A with an applic ation interval of 30 days (MRID 43680430). For the apple orchards studies, conducted in New York and Washington, the registrant repor ted DT50’s for pyridaben after th e first and second applications. The DT50’s were consistent with a range of 6-12 days. For the citrus grove studies, conducted in California and Florida, the regi strant reported overall nonlinear DT50’s, which were 14 days in California, and 12 days in Florida. Calculated DT50’s and DT90’s from each study are
summarized below in Table B.2.

Table B.2. Summary of DT50s from Terrestrial Field Dissipation Studies for Pyridaben.

Study DT50 Comments DT90 MRID

New York Apples 7.5 days Mean of two
values 214 days 43909904

Washington Apples 10 days Mean of two
values 188 days 43909904

Florida Citrus 12 days None 120 days 43680430

California Citrus 14 days None 629 days 43680430



### -41 of 62-

### It should be noted that in all ca ses the initial rate of dissipation of pyridaben was faster, likely due to soil photolysis, with some potential fo r volatilization, with mu ch slower dissipation afterwards (calculated DT90s ranged from 120 to 629 days). Parent pyridaben remained in the upper 0-6" soil level, except for rare trace levels in the 6-12" soil level in Washington and California only. Six metabolites of pyridaben were monitored: P-14, P-16, PB-4, PB-7, PB-9, and PB-14, Trace levels of some of these compounds were occasionally detected in the 0-6" soil level only.

There are also three additional supplemental studies that are di scussed below. In a Confined
Terrestrial Field Diss ipation study (MRID 43792112), 14 

### C-pyridaben was applied to a loamy sand. Based on non-linear DT50’s, the following results were reported:

DT 50 

### pyridazinone labeled parent 71 days

DT 50 

### benzene labeled parent 1 day

There were glaring differences in the DT50’s for the two labels. Despite the differences in DT50s it was apparent in both studies that the de gradation of pyridaben was biphasic. Essentially
all the residues remained in the 0-3" soil de pth. The following degradat es were monitored and found only in small amounts ( < 2.85% of the total applied) : PB -4, PB-7, PB-9, PB-14, P-14, and

P-16.

In another supplemental study, an Outdoor A quatic Microcosms study of pyridaben (MRID 43792108), conducted in Palm Beach County, Florida, three levels of application were used: 0.34 μg/L, 3.4 μg/L, and 34 μg/L. Based on the results obtained, post-appli cation half-lives for the low, mid, and high treatment concentrations in water were 28.5, 21.2, and 23.0 hours, respectively. The residue concentrations of pyridab en in sediment at the highest application rate (34 ppt) gave a DT50 of approximately 9.8 days.

Thirdly, a supplemental confined Aquatic field dissipation stu dy was conducted using radiolabeled pyridaben (MRI D 43792112). Pyridaben degraded ra pidly to a large number of minor products after 3 DAT. The half-life fo r the benzene label was 0.28 days, and for the pyridazinone label it was 0.99 days.

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### APPENDIX C: Characterization of Ec ological Effects Data for Pyridaben

C.1. Effects to Aquatic Organisms

Toxicity to aquatic fish and i nvertebrates is categorized using the definitions provided in Table C1 (U.S. EPA, 2004). Toxicity categories fo r aquatic plants have not been defined.

Table C1. Categories of Acute Toxicity for Fish and Aquatic Invertebrates.

LC 50 (mg a.i./L) Toxicity Category

< 0.1 Very highly toxic

> 0.1 - 1 Highly toxic

> 1 - 10 Moderately toxic

> 10 - 100 Slightly toxic

> 100 Practically nontoxic



### The available acute and chronic toxicity data for aquatic orga nisms exposed to pyridaben are from registrant-submitted studies conducted in the laboratory. The data summarized below correspond to exposures involving the technical grade active i ngredient (TGAI) pyridaben.

Some supplemental data are available from outdoor mesocosm studies that were conducted with formulated products containing pyridaben (MRIDs 43792103, 43792104, 43792105, 43792108, 44039601, 53792107). These studies are not described in this problem formulation, but may be considered for characterization purposes in future risk assessments of pyridaben.

An ECOTOX search that was conducted on Se ptember 15, 2009, identified several studies containing acute and chronic toxicity data fo r aquatic organisms (Rand and Clark 2000a; Rand and Clark 2000b; Rand et al. 2000; Rand et al. 2001). Rand and Clark 2000a present acute and chronic toxicity data for seve ral species of freshwater a nd estuarine/marine fish and invertebrates. The reported details of these studies ( i.e. , concentration range tested, slope, effect and NOEC) are consistent with those provided by the registrant in the flow through tests for these species that are described below. Rand and Clark 2000b, Rand et al. 2000 and Rand et al. 2001 present effects data from microcosms, wh ich are not considered for this problem
formulation.

C.1.1. Freshwater Fish

Pyridaben is very highly toxic to freshwater fish on an acute e xposure basis. The most sensitive acute endpoint is a 96-h LC 50 

### of 0.72 μg a.i./L for rainbow trout ( Oncorhynchus mykiss; MRID 43680402). Registrant submitted acute toxicity data for fish exposed to pyridaben are
summarized in Table C2.

-43 of 62-

### Table C2. Acute toxicity data for freshwat er fish exposed to pyridaben (TGAI; 98-100% a.i.). LC 50 

### values are based on mean-measured concentrations.
Species Common

name Flow/static 96-h LC 50 (μg a.i./L) 95% C.I. Slope Citation (MRID)

Flow 3.43 3.13-3.80 4.95 43680401 Lepomis
macrochirus Bluegill
sunfish Static (renewal) 2.52 1.85-3.2 5.01 42680110

Flow 0.72 0.63-0.83 6.86 43680402 Static (renewal) 2.3 1.9-2.68 5.68 42680109 Oncorhynchus mykiss Rainbow Trout

Flow 3.2 NA NA 43680403

NA = not available



### Chronic toxicity data are available from a full life cycle test conducted with the fathead minnow ( Pimephales promelas ). Growth (length and weight) of the F 0 

### and F 1 

### generations, as well as
survival of the F 1 

### generation were significantly decreased re lative to controls at 0.555 μg a.i./L. The resulting study NOAEC was 0.277 μg a.i./L (MRID 43792106).This study reported a 96-h

LC 50 

### of 2.3 μg a.i./L for fish (30-d old) from the same lot that was tested in the full life cycle test. Although the study report did not provide the raw mort ality data for the acute test, these data can
be used to characterize th e acute to chronic ratio ( i.e. , LC 50 

### /NOEC = 8.3) of pyridaben to fathead
minnows.

C.1.2. Freshwater Invertebrates

Pyridaben is very highly toxic to freshwater invertebrates on an acute exposure basis. Data are
available from two acu te studies involving Daphnia magna . In a static test, the 48-h EC 50 

### was 0.53 (0.47-0.61) μg a.i./L (MRID 42680111). In a flow-through test, the 48-h EC 50 

### was 1.02 (0.90-1.16) μg a.i./L (MRID 43680404).

In a registrant submitted chronic semi-static study with D. magna , a decrease in adult survival (10% relative to controls ) and a decrease in reproduction (6% decrease in numb er of offspring per female) was observed at the lowest treatmen t level, resulting in a NOAEC <0.013 μg a.i./L (MRID 43680410). This study was classified suppleme ntal and will not be used for establishing the chronic endpoint for freshw ater invertebrates due to high variability in exposure concentrations (average declin es of >40% in concentration within 2 days of exposure).

In a second chronic study with D. magna , time to reproduction was significantly affected at 0.086 μg a.i./L, with a NOAEC of 0.044 μg a.i./L (MRID 43680408).The second study was conducted under flow-through conditions, with cons istent exposure concentrations. Therefore, the NOAEC from this study is considered more reliable than the NOAEC derived from MRID
43680410. This NOAEC will be used in future eco logical risk assessments of pyridaben.

C.1.3. Estuarine/marine Fish

Pyridaben is very highly toxic to estuarine/marine fish on an acute exposure basis. This is based
on one 96-h LC 50 

### value of 17.2 (13.3-26.5) μg a.i./L for sheepshead minnow ( Cyprinodon variegates ; MRID 43680406). This study was classified su pplemental because the highest test concentration resulted in 50% mortality, l eading to uncertainty in the established LC 50



### .

-44 of 62-

### C.1.4. Estuarine/marine Invertebrates

Pyridaben is very highly toxic to estuarine/marine invertebrates on an acute exposure basis. This
is based on a 96-h LC 50 

### value of 0.67 (0.54-0.94) μg a.i./L for mysid shrimp ( Mysidopsis bahia; MRID 43680405) and a 96-h EC 50 

### of 5.7 μg a.i./L for reduction of shell deposition in the Eastern oyster ( Crassostrea virginica ; MRID 43680407).

In a 35-d chronic flow-through study with mysid shrimp, no reproductive, growth or survival effects were observed in expos ures as high as 0.13 μg a.i. /L (MRID 43680409). This study was classified supplemental due to poor control perf ormance and lack of observed effects at any treatment level. Despite this uncertainty, this endpoi nt will be used in future risk assessments of pyridaben if no additional acceptable or supplemental data are available.

C.1.5. Aquatic Plants

Data from Tier 1 studies are available for 4 species of non-vascular plants ( Navicula pelliculosa, Skeletonema costatum, Anabaena flos-aquae and Selenastrum capricornutum ) exposed to pyridaben for 5 d under static conditions. Re ported concentrations were based on initial measured values. Pyridaben was not detected at the conclusion of the studies. Percent inhibiton of cell density at the test c onclusions are provided in Tabl e C3 (MRID 43680422). In a Tier II
test with S. capricornutum, an EC 50 

### was estimated as >665 μg a.i./L (MRID 43680421).

Table C3. Observed inhibition of growth of non-vascular and vascular plants exposed to pyridaben in Tier 1 tests (MRID 43680422).

% inhibition of treatment level compared to controls Species Common name Initial

exposure concentration

(μg a.i./L) Negative Solvent

Navicula pelliculosa Freshwater diatom 13.6 0.5 none Skeletonema costatum Saltwater diatom 16.1 16 24 Anabaena flos-aquae Blue-green algae 13.4 11 none Selenastrum capricornutum Green algae 17.3 none none Lemna gibba duckweed 16.2 7 none



### A 14-d Tier I toxicity test with duckweed ( Lemna gibba ) exposed to 16.2 μg a.i./L pyridaben resulted in a no decrease in frond production comp ared to the solvent cont rol and a 7% decrease in frond production compared to the negative control (MRID 43680422; Table C3). Because this was a tier 1 test, no EC 50 

### or NOAEC was established for duckweed exposed to pyridaben. The exposure concentration is based on the initial measured value. Pyri daben was not detected at the conclusion of the 14 d study.

-45 of 62-

### C.2. Effects to Terrestrial Organisms

Acute toxicity to terrestrial animals is cat egorized using the definitions provided in Table C4 (U.S. EPA, 2004). Toxicity categories for terrestrial plants have not been defined.

Table C4. Categories of Acute Toxicity for Avian and Ma mmalian Studies.

Toxicity Category Oral LD 50 (mg/kg-bw) Dietary LC 50 (mg/kg-diet)

Very highly toxic < 10 < 50
Highly toxic 10 - 50 50 - 500
Moderately toxic 51 - 500 501 - 1000

Slightly toxic 501 - 2000 1001 - 5000
Practically non-toxic > 2000 > 5000



### The available acute and chronic t oxicity data for terrestrial an imals exposed to pyridaben are from registrant-submitted studies conducted in the laboratory. The data summarized below correspond to exposures involving the technical grade active ingredient (TGAI) pyridaben. Terrestrial plant studies involved exposure s in the greenhouse to technical pyridaben.

As of February 15, 2010, no additional acute or chronic toxicity data for mammals or birds exposed to pyridaben were identified in the scientific literature (based on a search of ECOTOX).
Effects data are available in the scientific literature involving expos ures of arthropods to pyridaben; however these studies do not generate the endpoints used by EFED for beneficial insects ( i.e. , 48-h LD 50 

### ). No data have been identified in the scientific literature that involve exposures of plants to pyridaben.

C.2.1. Birds

Pyridaben is classified practically non-toxic to birds on an acute oral exposure basis. In an acute oral toxicity study with th e Northern bobwhite quail ( Colinus virginianus ), the LD 50 

### for technical pyridaben (98%) was >2250 mg/kg-bw (MRID 42680106). In an acute oral study with the mallard duck ( Anas platyrhyncos), the LD 50 

### was >2500 mb/kg-bw for technical pyridaben (98%) MRID 42680105). There were no mortalit ies in the treatment levels of either acute oral test.

On a subacute dietary basis, pyridaben is classifi ed slightly toxic to birds. Data are available from two registrant submitted studies where 8-d LC 50 

### values for technical pyridaben (98%) were 4688 mg/kg-diet for mallard duck (MRID 42680107) and >5620 mg/ kg-diet for bobwhite quail (MRID 42680108).

Reproductive toxicity studies are availabl e for the bobwhite quail (MRID 43792102) and the mallard duck (MRID 43792101) exposed to technical pyridaben (99.7%). In the mallard study, reproductive (decreases in eggs laid, eggs set, viable embryos, live 3 week embryos, normal hatchlings and hatch survival) and parental effect s (decrease in size of adult male testes and
decrease in number of female ova ries) were observed in birds fed pyridaben at levels as low as 500 mg/kg-diet (LOAEC). The resulting NOAEC for the mallard duck was 100 mg/kg-diet. In

-46 of 62-

### the bobwhite quail study, no statistically signifi cant reproductive or parental effects were observed at the highest test dose, re sulting in a NOAEC of 1000 mg/kg-diet.

C.2.2. Mammals

Pyridaben is moderately toxic to mammals on an acute oral exposure basis. The acute oral LD 50 

### for mice exposed to pyridaben was 383 (318-462) mg a.i./kg-bw for females and 424 (364-494) for males (MRID 42680120). The acute oral LD 50 

### (95% confidence interval ) for rats exposed to pyridaben was 570 (373-872) mg a.i./kg-bw for females and 1100 (510-2374) mg a.i./kg-bw for males (MRID 42680119).

In a 2-generation reproduction st udy, the LOAEC for pyridaben pa rental toxicity was 80 mg/kgdiet (6.31 and 7.82 mg/kg-bw/day for males and females, respectively) based on decreased body weights, body weight gains and food efficiency. No reproductive effects were observed at any test level, resulting in a reproductive LOAEC >80 mg/kg-diet. The study NOAEC was 28 mg/kg-diet (2.20 and 2.41 mg/kg-bw/day for ma les and females, respectively) (MRIDs 42680143 and 42680144).

C.2.3. Invertebrates

In an acute contact study, adult worker honey b ees were exposed to te chnical pyridaben (99.7%) for 44 hours. The resulting LD 50 

### was 0.024 (0.016-0.031) μg a.i./bee (MRID 43680423), indicating that pyrid aben is highly toxic to honey bees.

The toxicity of pyridaben applie d to foliage was evaluated for hone y bees after application of a formulated product containing py ridaben (76.8%) at 0.5 lbs a.i./A. At 2, 8 and 24 h after the application, 71.3%, 42.9% and 20.3% mortality, respectively, was observed in exposed adult worker bees (MRID 43680424).

In a literature study, caged bumbl e bees, honey bees, alkali bees a nd alfalfa leafcutter bees were exposed to alfalfa treated with 0.4 lb a.i./A pyr idaben (formulated product). Table C5 displays the reported % mortality in thes e species after 24 h of exposure to residues aged 2 and 8 h. Field residues aged 2 h resulted in mortality as high as 48% in alfalfa leafcu tter bees. Field residues aged 8 h resulted in mortality as high as 31% in honey bees exposed for 24 hours (Mayer et al. 1997).

Table C5. Percent mortality in bees exposed to alfalfa containing aged residues of pyridaben.

Bee Percent mortality from
residues a g ed 2 h Percent mortality from residues

a g ed 8 h

bumble bees 0 10
honey bees 23 31

alkali bees 36 15

alfalfa leafcutter bees 48 6



### -47 of 62-

### C.2.4. Plants

Seedling emergence and vegetative vi gor data are available for 6 sp ecies of dicots and 4 species of monocots exposed to technical pyridaben (MRIDs 436804-19 and -20) ( Table C6 ). These
data are from Tier I studies that were conducted at 0.5 lb a.i./A.

Table C6. Percent reduction of dry weight in monocot and dicot species exposed to technical pyridaben in Tier I seedling emergence and vegetative vigor.
% Reduction in dry weight observed in treatment level (0.5
lb a.i./A ) relative to control Species (common name)
Monocot/
dicot Seedling emergence ( MRID 43680419 ) Vegetative vigor ( MRID 43680420 ) Zea mays (Corn) monocot 22 1 Allium cepa (Onion) monocot none 1 Lolium perenne (Ryegrass) monocot none 14

Avena sativa (Oat) monocot none 8 Glycine max (Soybean) dicot none 4 Raphanus sativus (Radish) dicot none 11

Solanum esculentum (Tomato) dicot 23 18

Cucumis sativus (Cucumber) dicot none none
Brassica oleracea (Cabbage) dicot none 1

Lactuca sativa (Lettuce) dicot 13 11



### C.3. References Cited

Mayer, D. F., Lunden, J. D., and Kov acs, G. (1997). Susceptibility of Four B ee Species (Hymenoptera: Apoidea) to
Field Weathered Insecticide Residues. J.Entomol.Soc.BC 94: 27-30.

Rand, G. M. and Clark, J. R. (2000). Hazard/Risk Assessment of Pyridaben: I. Aquatic Toxicity and Environmental Chemistry. Ecotoxicology 9: 157-168.

Rand, G. M., Clark, J. R., and Holmes, C. M. (2000). Us e of Outdoor Freshwater Pond Microcosms: II. Responses of Biota to Pyridaben. Environ.Toxicol.Chem. 19: 396.

Rand, G. M., Clark, J. R., and Holmes , C. M. (2001). The Use of Outdoor Freshwater Pond Microcosms. III. Responses of Phytoplankton and Periphyton to Pyridaben. Environ.Toxicol. 16: 96-103.

Rand, G. M. and Clark, J. R. (2000). Hazard/Risk Assessment of Pyridaben: II. Outdoor Aquatic Toxicity Studies
and the Water-Effect Ratio. Ecotoxicology 9: 169-177.



### -48 of 62-

## APPENDIX D: QSAR estimate s of toxicities of pyridaben, PB-7 and PB-9 to aquatic organisms

D.1. ECOSAR

ECOSAR identifies three chemical classes for pyridaben, including hydrazines, vinyl/allyl halides and amides. For PB-7, the relevant classe s are the acid forms for pyridaben’s chemical classes. For PB-9, ECOSAR identifies the same classes as pyridaben, as well as the benzyl
alcohols. The ECOSAR estimated toxicities for pyridaben, PB-7 and PB-9 derived using the hydrazine, vinyl/allyl halide and amide classes are provided in Table D1.

Table D1. Estimated (using ECOSAR v.1.0) Toxici ties of Pyridaben a nd Its Degradates of Concern to Aquatic Organisms †

Estimated toxicity Taxa (endpoint) Measured toxicity of Pyridaben 1 Pyridaben PB-7 2,3 PB-9 4

Vinyl/allyl halides
FW fish (96-h LC 50 ) 0.72-3.43 89 45600 20900
FW invertebrate – daphnid (48-h LC 50 ) 0.53-1.02 37 66300 50000
Green Algae (96-h EC 50 ) >665 996 81700 451000
SW fish (96-h LC 50 ) 17.2 319 62000 19400
SW invertebrate – mysid shrimp (96-h LC 50 ) 0.67 33 67900 54000
Hydrazines
FW fish (96-h LC 50 ) 0.72-3.43 49 3723 808
FW invertebrate – daphnid (48-h LC 50 ) 0.53-1.02 4950 84500 10200
Green Algae (72-h EC 50 ) No data 0.0684 0.661 0.0635

Amides
FW fish (96-h LC 50 ) 0.72-3.43 85 33100 13600
FW invertebrate – daphnid (48-h LC 50 ) 0.53-1.02 159 307 9560
Green Algae (96-h EC 50 ) >665 87 3010 494

† Units in μg/L. measured toxicity values for pyridaben are provided for comparison purposes.

1 Study details in Appendix C.

2 Smiles code: c1cc(C(O)=O)ccc1CSC2=C(Cl)C(=O)N(C(C)(C)C)N=C2

3 ECOSAR multiplies all estimated values by 10 because of acid moiety.

4 Smiles code: c1cc(CO)ccc1CSC2=C(Cl)C(=O)N(C(C)(C)C)N=C2



### All three chemical classes predict acute toxicity values for fish and invertebrates exposed to pyridaben that are 1-2 orders of magnitude less toxic when compared to empirical data. Comparison of estimated fish and invertebrate va lues for pyridaben and PB -7 and PB-9 indicate that pyridaben is 2 orders of magnitude more toxi c when compared to its degradates of concern.

For green algae exposed to pyridaben, the empirical EC 50 

### is greater than 665 μg a.i./L. The
estimated EC 50 

### for the vinyl/allyl halide class is on the same order of magnitude ( i.e. , 996 μg/L) compared to the empirical data; however, the estimated value for the amide class is 1 order of magnitude more toxic. Comparison of estimated algae values for pyridaben and PB-7 and PB-9 indicate that pyridaben is 1-3 or ders of magnitude more toxic when compared to its degradates of

-49 of 62-

### concern. Because no empirical 72-h EC 50 

### data are available for green algae exposed to pyridaben, the estimated values generated us ing the hydrazine class are not considered.

D.2. ASTER

ASTER predicts acute toxici ty values for fish and D. magna exposed to pyridaben that are 1-2 orders of magnitude less toxic wh en compared to empirical data. Comparison of estimated fish values for pyridaben and PB-7 and PB-9 indicate that pyridaben is 1 or der of magnitude more toxic to fish when compared to its degradates of concern. For D. magna , the estimated toxicity of PB-7 is on the same order of magnitude as the parent, and PB-9 is an order of magnitude less
toxic.

Table D2. Estimated (using ASTER) Acute Toxi cities of Pyridaben a nd Its Degradates of Concern to Aquatic Organisms †

Estimated toxicity Taxa (endpoint) Measured toxicity of Pyridaben 1 Pyridaben PB-7 2,3 PB-9 4

Rainbow trout (96-h LC 50 ) 0.72-3.2 963 5402 27325
Bluegill sunfish (96-h LC 50 ) 2.52-3.43 2176 11024 50669
Fathead minnow (96-h LC 50 ) 2.3 2598 13616 64618
Daphnia magna (48-h LC 50 ) 0.53-1.02 1660 7983 34918

† Units in μg/L. measured toxicity values for pyridaben are provided for comparison purposes.

1 Study details in Appendix C.

2 Smiles code: c1cc(C(O)=O)ccc1CSC2=C(Cl)C(=O)N(C(C)(C)C)N=C2

3 ECOSAR multiplies all estimated values by 10 because of acid moiety.

4 Smiles code: c1cc(CO)ccc1CSC2=C(Cl)C(=O)N(C(C)(C)C)N=C2



### -50 of 62-

## APPENDIX E: PRZM/EXA MS Input Parameters

Table D.1. Chemical-Specific PRZM/EXAMS Input Parameters Used in Aquatic Exposure Modeling for pyridaben. 1

Input Parameter Value Reference Comment

Molecular mass (g/mol) 364.9 42676103 Vapor pressure (torr) 8.21 x 10 -5 42676103 Henry's law constant (atm-m 3 /mol) 6.84 x 10 -3

-- Estimated (VP/WSol)

Water solubility (mg/L) 0.012 42676103 Organic carbon partitioning coefficient (K OC, L·kg -1 ) 66,525 42680155 Mean of four values (USEPA, 2009)

Aerobic soil metabolism

t 1/2 (days) 330 42680154 3x aerobic soil t 1/2 (110 days; USEPA, 2009)

Aerobic aquatic
metabolism t 1/2 (days) 660 No data No acceptable data, therefore 2x
Aerobic soil t 1/2 (330 days; USEPA, 2009) Anaerobic aquatic
metabolism t 1/2 (days) 0 42680154 Compound is stable to anaerobic microbial degradation.

Hydrolysis t 1/2 (days) 0 42680153 Compound is stable to hydrolytic degradation. Aqueous photolysis t 1/2 (days) 0.06 43680427

Foliar extraction 0.5 USEPA, 2009 Default Decay rate on foliage (days) 0 USEPA, 2009 Assume stable (default)

1 Application information, and management practices are listed in Table 3.1.



### -51 of 62-

## APPENDIX F: Data Call-In Tables

The Environmental Fate and Effects Division (EFE D) has completed a Data Call-In (DCI) table for the pyridaben environmental fate and effects da ta gaps identified in this Registration Review
Problem Formulation. The attached DCI tabl es, which include the guideline number and study title for required data, also pr ovide a rationale for requiring the data, an explanation of how the data will be used, and a brief description of how the data coul d impact the Agency’s future decision-making.

Guideline Number: 835.4100 Study Title: Aerobic Soil Metabolism Rationale for Requiring the Data Acceptable data on the aerobic soil metabolism of pyridaben are required under 40 CFR Part 158, Subpart N (revised July 1, 2009) for labeling that terrestrial outdoor uses. The Agency has a limited understanding of how pyridaben behaves in soil once applied. Depending on how quickly, to what extent, and to which transformation products the compound degrades, pyridaben may or may not pose potential exposure concern. Because the submitted aerobic soil metabolism study (MRID 43680128 ) only reported acceptable data from one soil that analyzed py ridaben biodegradation, this degradation route is not well understood. Therefore, the Agency is re quiring an aerobic soil metabolism study conducted on three additional relevant soils of different organi c carbon content, pH, clay content, and microbial
biomass. Practical Utility of the Data

How will the data be used?
Additional aerobic soil metabolism data will facilitate a better understanding of the fate of pyridaben residues in soil. If data indicate that degradati on in aerobic soil occurs rapidly and produces nontoxic transformation products, then the Agency could potentially determine that pyridaben residues of concern do not persist in soil under aerobic conditions. If data indicate that degradation is not appreciable in soil or that the transformation products are of similar or higher toxicity than the parent compound, then the Agency could conclude that pyridaben residues of concern persist in soil un der some aerobic conditions.

How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the required data, the half-life w ith be multiplied by three, per guidance, due to uncertainty from using a single value. If the require d data indicate that pyridaben in aerobic soils is rapidly biodegraded to nontoxic transformation product s, then risk assessment conclusions and associated labeled use precautions and/or restricti ons could be made less restrictive.

Guideline Number: 835.4300 Study Title: Aerobic Aquatic Metabolism Rationale for Requiring the Data Acceptable data on the aerobic aquatic metabolism of pyridaben are required under 40 CFR Part 158, Subpart N (revised July 1, 2009) for labeling that in cludes terrestrial outdoor uses. The Agency has a limited understanding of how pyridaben behaves in aquatic environments on ce applied. Depending on how quickly, to what extent, and to which transformation products the compound degrades, pyridaben may or may not pose potential exposure concern in wate r. Because pyridaben bi odegradation in aquatic environments is not well understood, the Agency is requiring an aerobic aquatic metabolism study conducted at different pH levels.



### -52 of 62-Practical Utility of the Data

How will the data be used? Aerobic aquatic metabolism data will facilitate a better understanding of th e fate of pyridaben residues in water. If data indicate that degradation in aerobi c conditions occurs rapidly in water and produces nontoxic transformation products, then the Agency coul d potentially determine that pyridaben residues of concern do not persist in water unde r aerobic conditions. If data indicate that degradation is not appreciable in aquatic environments or that the transf ormation products are of similar or higher toxicity than the parent compound, then the Agency could conc lude that pyridaben residues of concern persist in aerobic aqueous conditions.

How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the required data , pyridaben will be conservatively assumed stable to aerobic aquatic metabolism. If the required data indicate that pyri daben in aerobic, aqueous environments is rapidly biodegraded, then risk assessment conclusions and asso ciated labeled use precautions and/or restrictions
could be made less restrictive.

Guideline Number: 835.4400 Study Title: Anaerobic Aquatic Metabolism Rationale for Requiring the Data Acceptable data on the anaerobic aquatic metabolism of pyridaben are required under 40 CFR Part 158, Subpart N (revised July 1, 2009) for labeling that in cludes terrestrial outdoor uses. The Agency has a limited understanding of how pyridaben behaves in anaerobic aquatic environments following application. Depending on how quickly, to what extent, and to which transformation products the compound degrades, pyridaben may or may not pose potential exposure concern in water. Because pyridaben biodegradation in aquatic environments, pa rticularly oxygen-limiting environments, is not well understood, the Agency is requiring an anaerobic aqua tic metabolism study conducted at different pH
levels. Practical Utility of the Data

How will the data be used? Anaerobic aquatic metabolism data w ill facilitate a better understanding of the fate of pyridaben residues in water, particularly oxygen-limiting environments . If data indicate that degradation in anaerobic aqueous conditions occurs rapidly and produces nontoxic transformation products, then the Agency could potentially determine that pyridaben residues of concern do not persist in water under anaerobic conditions. If data indicate that degradation is not appreciable in water or that the transformation products are of similar or higher toxicity than the parent compound, then the Agency could conclude that pyridaben residues of concern pers ist in anaerobic aqueous conditions.

How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the required data , pyridaben will be conservatively assumed stable to anaerobic aquatic metabolism, since the default assumption is to use the anaerobic soil metabolism study, which is stable. If the required data indicate that pyridaben in anaer obic, aqueous environments is rapidly biodegraded,
then risk assessment conclusions and associated labele d use precautions and/or restrictions could be made
less restrictive.

Guideline Number: 835.6100 Study Title: Storage Stability Rationale for Requiring the Data The Agency has a limited understanding of how pyri daben behaves in frozen storage conditions between the time of sampling and the time of analysis. Subm ission of a storage stability study is essential in order to be confident that any degradation measured in the t est system was due solely to the environment of that



### -53 of 62-test system, and not due to handling and storage.

Practical Utility of the Data

How will the data be used? Storage stability data will facilitate a better understanding of the fate of pyridaben residues during storage and handling between sampling and analysis. If data indicate that degradation of pyridaben or its degradates occur then the data from the field studies are no longer valid as it would not be feasible to determine if the degradation measured in the test syst em was due solely to the environment of that test system, and not due to handling and storage.

How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the required data, the field data for pyridaben will be qualitatively used in the risk assessment. These data are used for confirmatory data to ensure that any degradation observed in the test systems is due solely to the test e nvironment and not handling or storage.

Guideline Number: 835.6200 Study Title: Analytical Method (and Associated Independent Laboratory Validation) for Residues
in Water Rationale for Requiring the Data Independently validated analytical methods for resi dues in soil, water, sediment, and plant material (environmental chemistry methods) submitted by the regist rant are used to evaluate analyses described in submitted environmental fate and ecological effects studies. Submitted analytical methods are also used by various Federal, State, Tribal, and local agenci es to detect and monitor residues that are or are suspected to be in environmental compartments due to outdoor uses and accidental releases. Independent laboratory validations for submitted analytical methods are necessary to confirm that the methods are
functional and to confirm the leve ls of detection and quantitation reported in registrant-prepared
validations.

Use of pyridaben may impact surface water quality due to runoff of rain water and drift of residues. This is especially true for poorly draining soils, erodibl e soils, and soils with shallow ground water. Therefore, outside agencies may request analytical methods with which to monitor for pyridaben residues
in water. Practical Utility of the Data

How will the data be used? In the absence of independently validated enviro nmental chemistry methods , submitted environmental fate and ecological effects data may not be revi ewable and entities outside the Agency may lack chemical-specific methods for analyses in enviro nmental compartments. Independently validated environmental chemistry methods will be used to evaluate newly submitted environmental fate and ecological effects data and will be made availabl e for enforcement and monitoring purposes at the federal, state, and local levels.

How could the data change the Agency’s decision, or impact the Agency’s future decision-making?
Risk assessment conclusions could be altered if th ey are not supported by either study data or environmental monitoring detections that are based on independently validated environmental chemistry methods. Furthermore, while not directly related to Agency decision-making, independently validated environmental chemistry methods are necessary to ensure the safety of those in proximity to releases of pyridaben residues in the environment.



### -54 of 62-Guideline Number: 835.6100 Study Title: Analytical Method (and Associated Independent Laboratory Validation) for Residues
in Soil Rationale for Requiring the Data Independently validated analytical methods for resi dues in soil, water, sediment, and plant material (environmental chemistry methods) submitted by the regist rant are used to evaluate analyses described in submitted environmental fate and ecological effects studies. Submitted analytical methods are also used by various Federal, State, Tribal, and local agenci es to detect and monitor residues that are or are suspected to be in environmental compartments due to outdoor uses and accidental releases. Independent laboratory validations for submitted analytical methods are necessary to confirm that the methods are
functional and to confirm the leve ls of detection and quantitation reported in registrant-prepared
validations. Practical Utility of the Data

How will the data be used? In the absence of independently validated enviro nmental chemistry methods , submitted environmental fate and ecological effects data may not be revi ewable and entities outside the Agency may lack chemical-specific methods for analyses in enviro nmental compartments. Independently validated environmental chemistry methods will be used to ev aluate submitted environm ental fate and ecological
effects data and will be made available for enforcemen t and monitoring purposes at the federal, state, and
local levels.

How could the data change the Agency’s decision, or impact the Agency’s future decision-making?
Risk assessment conclusions could be altered if th ey are not supported by either study data or environmental monitoring detections that are based on independently validated environmental chemistry methods. Furthermore, while not directly related to Agency decision-making, independently validated environmental chemistry methods are necessary to ensure the safety of those in proximity to releases of pyridaben residues in the environment.

Guideline Number: 850.1710 Study Title: Bioconcentration in oysters Rationale for Requiring the Data Empirical BCFs from two separate laboratory st udies involving rainbow trout (MRID 43792113) were
342 and 439. BCF values are also available from a life cycle test with fathead minnows, BCF values ranged 1168-3780 (MRID 43792106). KABAM was used to estimate a fish BCF that considers metabolism and steady state. When the metabolism rate is estimated from the empirical BCF studies with the rainbow trout, estimated BCF for fish is 5740. Although metabolism by fish reduces the bioconcentration potential of pyridaben, this estim ated BCF value is still sufficient to indicate that pyridaben may bioaccumulate in aquatic ecosystems. At this time, no empirical data are available that consider bioconcentration of pyrida ben in aquatic invertebrates. Therefore, bioconcentration data are required for oysters. Practical Utility of the Data

How will the data be used? Bioconcentration data for oysters will increase th e understanding of the bioaccumulation potential of pyridaben in aquatic ecosystems. Although empirical BCF data indicate that pyridaben is metabolized in fish, the ability of aquatic invertebrates to metaboli ze pyridaben is unknown. Me tabolism is an important consideration in determining the bioaccumulati on potential of a chemical because metabolism can decrease the bioaccumulation of that chemical. In the case of fish exposed to pyridaben, metabolism by fish decreases the bioaccumulation pot ential of pyridaben. BCF data for oysters will provide information on the potential of aquatic invert ebrates to metabolize pyridaben.



### -55 of 62-How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the required data, EFED will assume that pyridaben is not metabolized by aquatic invertebrates. This is a conservative assumption th at could potentially overestimate bioaccumulation of pyridaben in aquatic organisms if this chemical is actually metabolized by aquatic invertebrates. Alternatively, if the BCF study with oysters indicates that pyridaben is not metabolized by oysters, these data will support the conservative assumption of no metabolism by aquatic invertebrates, thereby increasing the certainty in the model estimates bioaccumulation.

Guideline Number: 850.1850 Study Title: Aquatic food chain transfer Rationale for Requiring the Data Empirical BCFs from two separate laboratory st udies involving rainbow trout (MRID 43792113) were
342 and 439. BCF values are also available from a life cycle test with fathead minnows, BCF values ranged 1168-3780 (MRID 43792106). KABAM was used to estimate a fish BCF that considers metabolism and steady state. When the metabolism rate is estimated from the empirical BCF studies with the rainbow trout, estimated BCF for fish is 5740. Although metabolism by fish reduces the bioconcentration potential of pyridaben, this estim ated BCF value is still sufficient to indicate that pyridaben may bioaccumulate in aquatic ecosystems. This study is required to determine the potential bioaccumulation of pyridaben.

Pyridaben registrants must submit a study protocol for review by the Agency prior to initiation of the aquatic food chain transfer study. Practical Utility of the Data

How will the data be used? Empirical bioaccumulation data will increase the understanding of the bioaccumulation potential of pyridaben in aquatic ecosystems.

How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the required data, EFED will assess the bioaccumulation potential of pyridaben using models and will make conservative assumptions in the place of data to refute the conservative assumptions ( e.g. , no metabolism of pyridaben by aquatic i nvertebrates). These empirical data will supplement model estimates.

Guideline Number: 850.3040 Study Title: Field testing for pollinators Rationale for Requiring the Data According to 40 CFR Part 158, this study is required if any of the following are met: 1) data from other sources (Experimental Use Permit program, uni versity research, registrant submittals, etc .) indicate potential adverse effects on colonies, especially effects other than acute mortality (reproductive, behavioral, etc .); 2) data from residual toxicity studies indicate extended residual toxicity; or 3) data derived from studies with terrestrial arthropods other than bees indicate potential chronic, reproductive or behavioral effects. In a foliar residue study MR ID (43680424), pyridaben residues aged 24 h caused mortality (> 20%) in honey bees. Therefore, the second condition relevant to this data requirement is met and submission of a field study of the effects of pyridaben on pollinators is required (Guideline 850.3040). Pyridaben registrants must submit a study pr otocol for review by the Agency prior to initiation of the field testing for pollinators study.

Practical Utility of the Data

How will the data be used?



### -56 of 62-Field testing data for pollinators ( i.e. , honey bees) will be used to iden tify potential risks to non-target, terrestrial invertebrates, including native pollinators, from chronic exposure to pyridaben. In this case, pyridaben will be present in the field as it is intende d to be applied according to labels. The data will
reduce uncertainties associated with the current risk assessment for terrestrial insects and will improve the Agency’s understanding of the potential effects of pyridaben on terrestrial species. If field testing effects data are not submitted, than risk to terrestrial insects from chronic exposure to pyridaben will not
be refuted.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are pe rformed without these data, the Agency would have to assume that pyridaben “may affect” listed terrest rial insects directly (and listed species from other taxa that rely upon terrestrial insects indirectly [ecol ogical services] through pollination), and use of pyridaben and its formulated products may need to be restrict ed in areas where listed species could be affected. The lack of these data will limit the flexibility the Agen cy and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for pyridaben use that are unnecessarily severe.

Guideline Number: 850.1075 Study Title: Estuarine/Marine Fish Acute Toxicity Test Rationale for Requiring the Data Acute toxicity data are available for sheepshead minnow exposed to pyridaben (43680406). This study was classified supplemental because the highest test c oncentration resulted in 50% mortality, leading to uncertainty in the established LC 50 . Submission of acceptable acute toxici ty data for estuarine/marine fish will reduce uncertainty associated with the acute e ndpoint and increase confidence in risk conclusions. Practical Utility of the Data

How will the data be used? Estuarine/marine fish acute toxicity data will be u sed to determine the potential for pyridaben to affect fish species in estuarine/marine environments. The data will reduce uncertainties associated with the
current risk assessment for estuarine/marine fish a nd will improve the Agency’s understanding of the potential effects of pyridaben on aquatic animals. In the absence of data specific for estuarine/marine fish, supplemental data from MRID 43680406 will be used.

How could the data impact the Agency’s future decision-making? Using toxicity data from a supplemental stud y increases the uncertainty for assessing risks to estuarine/marine species in screening-level assessments.

Guideline Number: 850.1400 Study Title: Saltwater fish early-life stage test Rationale for Requiring the Data Chronic toxicity data are not available for estuarine/marine fish. The Part 158 data requirements, specify that an early life-stage study is required for estuarine /marine fish for chemicals that have the potential to enter estuarine/marine water. In addition, these data may be required when the acute LC 50 for an estuarine/marine fish is <1 mg/L, and when reproducti ve effects are observed in other aquatic organisms. Because pyridaben use sites may overlap with waters heds of estuarine/marine environments, pyridaben pas the potential to enter estuarine/mar ine environments. In addition, the LC 50 for sheepshead minnow exposed to pyridaben is <1 mg/L (MRID 43680406) and reproductive effects have been observed in freshwater fish (MRID 43792106) and invertebra tes (MRIDs 43680408 and 43680410) exposed to pyridaben. Therefore, chronic fish toxi city data are required for pyridaben. Practical Utility of the Data

How will the data be used?



### -57 of 62-Chronic estuarine/marine fish toxicity data will be used to determine the potential for pyridaben to affect fish species in estuarine/marine environments fo llowing prolonged exposure. The data will reduce
uncertainties associated with the cu rrent risk assessment for estuarine /marine fish and will improve the Agency’s understanding of the potential effects of pyri daben on aquatic animals. In the absence of data specific for these fish, the Agency w ill use acute to chronic ratios available for freshwater fish exposed to pyridaben.

How could the data impact the Agency’s future decision-making? Using acute to chronic ratios increases the uncertain ty for assessing risks to est uarine/marine species in screening-level assessments.

Guideline Number: 850.1350 Study Title: Estuarine/Marine invertebrate life cycle test Rationale for Requiring the Data Supplemental chronic toxicity data are available for mysid shrimp exposed to pyridaben (43680409). This study was classified supplemental due to poor control performance and lack of observed effects at any treatment level. Submission of acceptable chronic toxicity data for estuarine/marine invertebrates will reduce uncertainty associated with the chronic en dpoint and increase confidence in risk conclusions. Practical Utility of the Data

How will the data be used? Estuarine/marine invertebrate chronic toxicity data will be used to determine the potential for pyridaben to affect invertebrates species in estuarine/marin e environments. The data will reduce uncertainties
associated with the current risk assessment for estuarine/marine i nvertebrates and will improve the Agency’s understanding of the potential effects of pyri daben on aquatic animals. In the absence of data specific for estuarine/marine invertebrates, supplemental da ta from MRID 43680409will be used.

How could the data impact the Agency’s future decision-making? Using toxicity data from a supplemental stud y increases the uncertainty for assessing risks to estuarine/marine species in screening-level assessments.

Guideline Number: 850.1735 Study Title: Whole sediment: acute freshwater invertebrates Rationale for Requiring the Data No data are currently available to characterize th e acute toxicity of pyridaben to sediment dwelling invertebrates. The Part 158 data requirements, specify that acute toxicity data for sediment invertebrates are conditionally required if the half-life of the pesticide in sediment >10 days in aerobic soil or aquatic
metabolism studies and if any of the following conditions exist: a) the K d is ≥ 50; b) the log K

ow is ≥ 3 or c) the K

oc is ≥ 1000. Since the half-live of pyridaben in soil under aerobic conditions is >10 days, the Log
Kow is >3 and the K

oc is >1000, acute toxicity data for one sp ecies of sediment-dwelling invertebrate are required for pyridaben. Practical Utility of the Data

How will the data be used? Invertebrate acute toxicity data will be used to de termine the potential for pyridaben to affect sedimentdwelling aquatic invertebrates. The data will reduce uncertainties associated with the current risk assessment for sediment-dwelling invertebrates an d will improve the Agency’s understanding of the potential effects of pyridaben on aquatic animals.

How could the data impact the Agency’s future decision-making? Using toxicity data from a species inhabiting the water column as a surrogate for sediment-dwelling species increases the uncertainty for assessing risks to aquatic species in screening-level assessments,



### -58 of 62-especially because pyridaben is likely to partition to sediments. Additionally, if future endangered species risk assessments are perform ed without these data, the Agency would have to presume risk to listed sediment dwelling invertebrate species ( e.g ., mollusks) in the absence of such data for pyridaben. Therefore, the use of pyridaben and its formulated products may need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for pyridaben that are unnecessarily severe.

Guideline Number: no guideline Study Title: Whole sediment: ch ronic freshwater invertebrates Rationale for Requiring the Data No data are currently available to characterize the chronic toxicity of pyridaben to sediment-dwelling invertebrates. The Part 158 data requirements, specify that chronic toxicity data for sediment invertebrates are conditionally required if the EEC in sediment is >0.1 of the acute LC/EC 50 values and the half-live of the pesticide in the sediment is >10 days in aerobic soil or aquatic metabolism studies and if any of the following conditions exist: a) the K d is ≥ 50; b) the log K

ow is ≥ 3 or c) the K

oc is ≥ 1000. Since the acute toxicity of pyridaben to sediment- dwelling invertebrates is unknown due to a lack of effects data, the relationship between the EEC and the acute toxicity cannot be determined. However, the half-live of pyridaben in soil under aerobic conditio ns is >10 days, the Log Kow is >3 and the K

oc is >1000. Therefore, chronic toxicity data for one sp ecies of sediment-dwelling invertebrate are required for pyridaben. Pyridaben registrants must submit a study protocol for review by the Agency prior to initiation of the chronic toxicity study with sediment dwelling invertebrates. Practical Utility of the Data

How will the data be used? Invertebrate chronic toxicity data will be used to determine the potential for pyridaben to affect sediment dwelling aquatic invertebrates. The data will reduce uncertainties associated with the current risk assessment for sediment dwelling invertebrates an d will improve the Agency’s understanding of the potential effects of pyridaben on aquatic animals.

How could the data impact the Agency’s future decision-making? Using toxicity data from a species inhabiting the water column as a surrogate for sediment dwelling species increases the uncertainty for assessing risks to aquatic species in screening-level assessments, especially because pyridaben is likely to partition to sediments. Additionally, if future endangered species risk assessments are perform ed without these data, the Agency would have to presume risk to listed sediment dwelling invertebrate species ( e.g ., mollusks) in the absence of such data for pyridaben. Therefore, the use of pyridaben and its formulated products may need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for pyridaben that are unnecessarily severe.

Guideline Number: 850.4100 Study Title: Terrestrial Plant Toxicity Test, Tier I (Seedling Emergence) Rationale for Requiring the Data According to the 850.4100 guideline, seedling emergence data are required for a total of 10 plant species, including 4 monocot and 6 dicot species. The 4 monocot species must be from at least 2 families. One species of monocots must be corn. The 6 dicot spec ies must be from 4 different families, and must include soybean and a root crop.

Tier 1 data must test up to the highest single application rate allowed for a pesticide. If the Tier I data result in significant decreases in endpoints compared to controls or >25% effects to any test species, Tier



### -59 of 62-II data should be submitted for that species. Both Ti er I and Tier II seedling emergence studies must be conducted with a typical end use product.

Tier 1 data were submitted for seedling emergence study were plants were exposed to 0.5 lb a.i./A technical pyridaben (MRID 43680419). There are 2 uses of pyridaben (SLN on Pears and ornamentals) that have single application rates that exceed 0.5 lb a.i./A. This study was not conducted with a typical end use product. Therefore, guidelin e 850.4100 represents a data gap. In order to fulfill these guidelines, additional Tier 1 seedling emergence and vegetative vigor studies are required. These studies must be conducted at the highest single application rate for py ridaben (1.0 lbs a.i./A on ornamentals) and with a typical end use product containing pyridaben.

If the Tier I data result in >25% effects to any test species, Tier II data should be submitted for that species. Practical Utility of the Data

How will the data be used? Seedling emergence data for terrestrial plants will be used to determine the potential for pyridaben to affect non-target plant species in the terrestrial envi ronment. The data will reduce uncertainties associated
with the current risk assessment for terrestrial plants and will improve the Agency’s understanding of the potential effects of pyridaben on terrestrial plants. In the absence of data sp ecific for these plants, for uses with applications of 0.5 lb a.i./A, it will be assumed that <25% effects occur. For uses with applications >0.5 lb a.i./A, risk cannot be precluded.

How could the data impact the Agency’s future decision-making? Because terrestrial plants form the basis of the food chain in many terrestrial habitats, a solid understanding of the potential risks to terrestrial plants is essential for sound environmental risk management decision-making. Submission of seedling emergence data conducted at the highest single application rate and with a typical end use product w ill increase the Agency’s certa inty in the measures of pyridaben’s toxicity to plants.

Guideline Number: 850.4150 Study Title: Terrestrial Plant Toxicity Test, Tier I (Vegetative Vigor) Rationale for Requiring the Data According to the 850.4150 guideline, vegetative vigor data are required for a total of 10 plant species, including 4 monocot and 6 dicot species. The 4 monocot species must be from at least 2 families. One species of monocots must be corn. The 6 dicot spec ies must be from 4 different families, and must include soybean and a root crop.

Tier 1 data must test up to the highest single application rate allowed for a pesticide. If the Tier I data result in significant decreases in endpoints compared to controls or >25% effects to any test species, Tier II data should be submitted for that species. Both Ti er I and Tier II vegetative vigor studies must be conducted with a typical end use product.

Tier 1 data were submitted for vegetative vigor study were plants were e xposed to 0.5 lb a.i./A technical pyridaben (MRID 43680420). There are 2 uses of pyrida ben (SLN on Pears and ornamentals) that have single application rates that exceed 0.5 lb a.i./A. This study was not conducted with a typical end use product. Therefore, guideline 850.4150 represents a data gap. In order to fulfill these guidelines, additional Tier 1 seedling emergence and vegetative vigor studies are required. These studies must be conducted at the highest single application rate for py ridaben (1.0 lbs a.i./A on ornamentals) and with a typical end use product containing pyridaben.



### -60 of 62-If the Tier I data result in >25% effects to any test species, Tier II data should be submitted for that species. Practical Utility of the Data

How will the data be used? Seedling emergence data for terrestrial plants will be used to determine the potential for pyridaben to affect non-target plant species in the terrestrial envi ronment. The data will reduce uncertainties associated
with the current risk assessment for terrestrial plants and will improve the Agency’s understanding of the potential effects of pyridaben on terrestrial plants. In the absence of data sp ecific for these plants, for uses with applications of 0.5 lb a.i./A, it will be assumed that <25% effects occur. For uses with applications >0.5 lb a.i./A, risk cannot be precluded.

How could the data impact the Agency’s future decision-making? Because terrestrial plants form the basis of the food chain in many terrestrial habitats, a solid understanding of the potential risks to terrestrial plants is essential for sound environmental risk management decision-making. Submission of vegeta tive vigor data conducted at the highest single application rate and with a typical end use product w ill increase the Agency’s certa inty in the measures of pyridaben’s toxicity to plants.

Guideline Number: 850.5400 Study Title: Aquatic plant toxicity (Tier I): algae Rationale for Requiring the Data Supplemental Tier I data are available for 4 species of algae exposed to <20 μg a.i./L pyridaben (MIRD 43680422). In addition, a supplementa l Tier II study is available for green algae exposed to pyridaben (MRID 43680421). In order to fulfill the guideline requireme nt for algae, additional Tier I data must be submitted for 4 species of algae exposed to pyridaben at a concentration of 100 mg a.i./L (limit test). If the Tier I data result in >50% effects to any test sp ecies, Tier II data should be submitted for that species. Practical Utility of the Data

How will the data be used? Data from Tier I aquatic plant toxicity studies will be used to estimate potential risks to aquatic nonvascular plants from pyridaben exposure. The data will reduce uncertainties asso ciated with the current risk assessment for aquatic plants and will improve the Agency’s understanding of the potential effects of pyridaben on aquatic plants. In the absence of Tier I data, risks to non-vascular aquatic plants will be presumed.

How could the data impact the Agency’s future decision-making? Because aquatic non-vascular plants form the basis of the food chain for aquatic habitats and significantly contribute to overall water quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental risk management d ecision-making. Without aquatic plant data for pyridaben, the Agency cannot determine if the current application rates for pyridaben may result in direct adverse effects to aquatic plants and/or indirect effects resulting from reduction in the prey base and/or loss of habitat/cover. If future endangered species ri sk assessments are performed without these data, the Agency would have to assume that pyridaben “may a ffect” aquatic plants directly (and listed species from other taxa indirectly via reduction in prey base a nd/or habitat), and use of pyridaben may need to be restricted in areas where listed speci es could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for pyridaben which are unnecessarily severe.



### -61 of 62-Guideline Number: 850.4400 Study Title: Aquatic plant toxicity (Tier I): vascular plants Rationale for Requiring the Data Supplemental Tier I data are available for duckw eed exposed to <20 μg a.i./L pyridaben (MIRD 43680422). In order to fulfill the guideline requirement for aquatic vascular plants, additional Tier I data must be submitted for a vascular aquatic plant ( i.e. , duckweed) exposed to pyridaben at a concentration of 100 mg a.i./L (limit test). If the Tier I data result in >50% effects to the test species, Tier II data should be submitted for that species. Practical Utility of the Data

How will the data be used? Data from Tier I aquatic plant toxicity studies will be used to estimate potential risks to aquatic vascular plants from pyridaben exposure. The data will redu ce uncertainties associated with the current risk assessment for aquatic plants and w ill improve the Agency’s understa nding of the potential effects of pyridaben on aquatic plants. In the absence of Tier I data, risks to vascular aquatic plants will be presumed.

How could the data impact the Agency’s future decision-making? Because aquatic vascular plants form the basis of th e food chain for aquatic habitats and significantly contribute to overall water quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental risk management d ecision-making. Without aquatic plant data for pyridaben, the Agency cannot determine if the current application rates for pyridaben may result in direct adverse effects to aquatic plants and/or indirect effects resulting from reduction in the prey base and/or loss of habitat/cover. If future endangered species ri sk assessments are performed without these data, the Agency would have to assume that pyridaben “may a ffect” aquatic plants directly (and listed species from other taxa indirectly via reduction in prey base a nd/or habitat), and use of pyridaben may need to be restricted in areas where listed speci es could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for pyridaben which are unnecessarily severe.



### -62 of 62-