1

The results of this risk assessment indicate

that the proposed use of halauxifenͲmethyl

is not likely to result in direct risk to nonͲ

target terrestrial animals, including insects,

birds, reptiles, terrestrialͲphase

amphibians, and mammals. In addition, risk

to aquatic animals including amphibians,

fish, invertebrates, and aquatic nonvascular

plants are also not expected. However, the

proposed use of halauxifenͲmethyl may

pose a risk to terrestrial, semiͲaquatic and

aquatic vascular plants. This includes

agricultural crops grown near the

application site.

Ecological Risk

Assessment for the

New Herbicide

HalauxifenͲmethyl
MELISSA PANGER 

2015.12.16 07:14:05 -05'00'

JAMES HETRICK Digitally signed by JAMES HETRICK 

DN: c=US, o=U.S. Government, ou=USEPA, ou=Staff, cn=JAMES 

HETRICK, dnQualifier=0000005599 

Date: 2015.12.16 09:55:36 -05'00'
3

US20130143739) claims halauxifen and fluroxypyr cause “synergistic effects.” There is the

potential for this formulation, GFͲ2688, to be more highly toxic to plants than the other

formulations for which data are available. Data are not available to evaluate the claims of

synergy or to evaluate the relative risk of GFͲ2688 as compared to the other formulations.

The results of this risk assessment indicate that the proposed use of halauxifenͲmethyl is not

likely to result in direct risk to nonͲtarget terrestrial animals, including insects, birds, reptiles,

terrestrialͲphase amphibians, and mammals. In addition, risk to aquatic animals including

amphibians, fish, invertebrates, and aquatic nonvascular plants are also not expected.

However, the proposed use of halauxifenͲmethyl may pose a risk to terrestrial and semiͲaquatic

and aquatic vascular plants. This includes agricultural crops (e.g., soybean and sunflower)

grown near the application site.

Droplet size greatly influences the predicted distances from the application site at which plant

exposure to drift residues would no longer be of concern. Below are some examples of the

predicted distances at which nontarget plant exposure to drift residues would no longer be of

concern (see APPENDIX I for RQ for various drift distances):

Formulation GFͲ2685 (highest single rate of 0.00873 lb a.e./A)

Aerial application, nonlisted plants (Figure 5)

Ͳ Monocot (most sensitive tested is onion based on vegetative vigor)

o ~250 feet using coarseͲtoͲvery coarse droplets (at 50 feet, RQ = 5; at 100

feet, RQ = 2)

o ~700 feet using fineͲmedium droplets (at 50 feet, RQ = 65; at 100 feet, RQ =

7)

Ͳ Dicot (most sensitive tested is soybean based on vegetative vigor)

o > 2500 feet using coarseͲtoͲvery coarse droplets (at 50 feet, RQ = 66; at 300

feet, RQ = 8)

There is noted variability in sensitivity across the tested species: based on aerial

applications of fineͲtoͲmedium droplets, drift distances ofч50 feet are predicted for

some nonlisted plants (e.g., corn, oat, oilseed rape, tomato, sugar beet, and sunflower),

whereas drift distances of ~250 to >2500 feet are predicted for other nonlisted plants

(e.g., onion, carrot, cucumber, and soybean).

Aerial application, listed plants (Figure 6)

Ͳ Monocots (i.e., onion based on vegetative vigor) and dicots(i.e., soybean based on

vegetative vigor)

o ш2500 feet using fineͲmedium droplets and coarseͲtoͲvery coarse droplets

Ground application, nonlisted plants (Figure 7)

Ͳ Monocot (most sensitive tested is onion based on vegetative vigor)

o ~50 feet using coarseͲtoͲmedium coarse, low boom (at 10 feet, RQ = 2)

o ~200 feet using fineͲvery fine droplet, high boom (at 10 feet, RQ = 18; at 50

feet, RQ = 4)
4

Ͳ Dicot (most sensitive tested is soybean based on vegetative vigor)

o ~500 feet using coarseͲtoͲmedium coarse, low boom (at 10 feet, RQ = 28; at

50 feet, RQ = 6)

o >1000 feet using fineͲvery fine droplet, high boom (at 100 feet RQ = 226; at

300 feet RQ = 8)

Ground application, listed plants (Figure 8)

Ͳ Monocot (most sensitive tested is onion based on vegetative vigor)

o ~450 feet using coarseͲtoͲmedium coarse, low boom

o ~1000 feet using fineͲvery fine droplet, high boom

Ͳ Dicot (most sensitive tested is soybean based on vegetative vigor)

o ~600 feet using coarseͲtoͲmedium coarse, low boom (at 10 feet RQ = 33; at

50 feet RQ = 7)

o >1000 feet using fineͲvery fine droplet, high boom (at 100 ft RQ=22; at 300 ft

RQ = 8)

The vegetative vigor toxicity testing conducted with the GFͲ2687 endͲuse product showed

comparable effects as was observed with testing conducted using GFͲ2685. Following aerial

application of formulation GFͲ2687 (highest proposed single application of 0.0049 lb

halauxifen/A, and coͲformulated with florasulam), the distance from the application site where

risks to nonͲlisted terrestrial plants are no longer of a concern is at the edge of field for

monocots, and is 1500 feet to greater than 2500 ft for dicots (depending on droplet sizes;

Figure 9). For listed terrestrial dicots LOCs are exceeded out beyond 2500 ft for 5 of the tested

species with fineͲmedium droplets and 4 species with coarseͲvery coarse droplets (Figure

10). These distances are reduced when formulation GFͲ2687 is applied by ground sprays;

however, even with ground spray applications the risks to nonͲlisted dicots go out to 200 and

700 feet for coarse and fine droplets, respectively (Figure 11), and the listed species LOCs are

exceeded out beyond 2500 feet for dicots (Figure 12).

It should be noted, that pesticides within the same chemical class as halauxifenͲmethyl,

including picloram and aminopyralid, are mobile and persistent like halauxifenͲmethyl, and

could remain at toxic levels in compost materials as well as on the application site. In addition,

the persistence, mobility, and phytotoxicity also raise concern about persistent residues in

irrigation water and compost as potential exposure pathways. Several compost studies have

been submitted and were considered in this assessment. Some of the studies suggest that

halauxifenͲmethyl residues in treated crops (e.g., wheat) were below detectable levels or

quickly degraded when introduced into a compost system (e.g., via animal excrement).

However, there were extensive uncertainties and missing information to support these claims

(e.g., no reported application rate used; the level of detection; no residue analyses to confirm

mass balance or presence of halauxifen; lack of storage stability information to support

reported halfͲlives). Additionally, a bioassay study using composted wheat straw treated with

halauxifenͲmethyl claimed that observed effects were attributed to elevated salinity. While

salinity levels were high, the greatest effects were not seen in the samples with the highest

salinity. In summary, the studies do not dismiss compost as a potential route of exposure to

halauxifenͲmethyl or XDEͲ729 acid.
5

As for the analytical methods for soil and water, the limits of detection (LOD) and quantification

(LOQ) of halauxifenͲmethyl and XDEͲ729 acid, in soil (0.05 μg/kg and 0.02 μg/kg) and water

(0.05 μg/L), while quite low, are not low enough to detect residues in soil and water at the IC25

for terrestrial plants. The analytical methods are not sufficient for identifying the presence or

absence of these residues at levels equal to the most sensitive toxicological endpoints (e.g.,

IC05) identified for several terrestrial plants or aquatic organisms in this assessment. A recently

submitted soil method reports a lower LOD (0.00045 μg/kg) and LOQ (0.0015 μg/kg) for

halauxifenͲmethyl, XDEͲ729 acid in soil; however, no independent laboratory validation was

provided for this method. As such, this method has not been reviewed since it cannot be

confirmed. The reported lower LOD (0.00045 μg/kg) captures all toxicological endpoints

identified in this assessment except for sunflower. Analytical methods for halauxifenͲmethyl

and XDEͲ729 acid in compost (LOD = 0.02 μg/kg; LOQ = 0.05 μg/kg) were submitted; however,

no independent laboratory validation was provided, thus, the study was not reviewed as it

cannot be confirmed. Based on the reported compost LOD, the method is not sufficient for

identifying the presence or absence of halauxifenͲmethyl and XDEͲ729 acid at levels equal to

the toxicological endpoints for several species included in this assessment. In addition,

analytical methods are not available for detecting X11406790 in soil or degradates 1, 2, 4, 10,

11, and 14 in soil and water. These residues cannot be ruled out as residues of concern for

terrestrial plants.

EPA issued guidance (U.S. EPA, et. al., 2014) on the framework to conduct risk assessments for

pollinators (e.g., honey bees). EPA is unable at this time to conduct a full risk assessment for

pollinators (e.g., honey bees) exposed to halauxifenͲmethyl because EPA does not have a full

suite of toxicity data to assess potential risk to honey bees. Additional data needed in order to

conduct a full risk assessment for pollinators include the following studies:

1. Acute oral toxicity to larvae honey bees (NonͲguideline)

2. Chronic oral toxicity to adult honey bees (OECD 237)

3. Chronic oral toxicity to larval honey bees (NonͲguideline)

4. Honey bee toxicity of residues on foliage (Guideline 850.3030)

5. Field trial of residues in pollen and nectar (contingent on Tier 1 results) (NonͲguideline)

6. SemiͲfield testing for pollinator (contingent on Tier 1 results) (NonͲguideline, OECD

Guidance 75)

7. Field testing for pollinators (contingent on Tier 2 results) (Guideline 850.3040)

 
6

Ecological Risk Assessment for the New Herbicide

HalauxifenͲmethyl

N

NH2

Cl

O

O

Cl

O

F

HALAUXIFENͲMETHYL

Methyl 4ͲaminoͲ3ͲchloroͲ6Ͳ(4ͲchloroͲ2ͲfluoroͲ3Ͳmethoxyphenyl) pyridineͲ2Ͳcarboxylate

CAS No. 943831Ͳ98Ͳ9

 
7

TABLE OF CONTENTS

I. EXECUTIVE SUMMARY ...................................................................................................... 12

A. Nature of Chemical Stressor................................................................................. 12

B. ConclusionsͲExposure Characterization.............................................................. 13

C. ConclusionsͲEffects Characterization.................................................................. 14

D. Potential Risks to NonͲtarget Organisms.............................................................. 15

E. Uncertainties......................................................................................................... 15

II. PROBLEM FORMULATION................................................................................................. 16

A. Stressor Source and Distribution .......................................................................... 16

Source and Intensity ............................................................................................. 16

Pesticide Type, Class, and Mode of Action........................................................... 17

Overview of Pesticide Usage................................................................................. 17

Residues of Concern ............................................................................................. 17

Aquatic Animals ........................................................................................ 17

Aquatic Plants ........................................................................................... 18

Terrestrial Plants....................................................................................... 18

Physical/Chemical/Fate and Transport Properties............................................... 20

Degradation .......................................................................................................... 21

Hydrolysis.................................................................................................. 21

Aquatic Photolysis..................................................................................... 31

Soil Photolysis ........................................................................................... 32

Aerobic Soil Metabolism........................................................................... 32

Anaerobic Soil Metabolism....................................................................... 33

Aerobic Aquatic Metabolism .................................................................... 34

Anaerobic Aquatic Metabolism ................................................................ 34

Mobility and Transport ......................................................................................... 35

Batch Equilibrium...................................................................................... 35

Compost................................................................................................................ 40

Residue Carryover................................................................................................. 41

Bioconcentration................................................................................................... 42

B. Receptors.............................................................................................................. 42

Aquatic and Terrestrial Effects.............................................................................. 42

Ecosystems Potentially at Risk.............................................................................. 42

C. Assessment Endpoints.......................................................................................... 43

D. Conceptual Model................................................................................................. 43

Risk Hypothesis..................................................................................................... 44

Diagram................................................................................................................. 44

E. Analysis Plan ......................................................................................................... 47

Measures to Evaluate Risk Hypotheses and Conceptual Model .......................... 47

F. Measures of Effect................................................................................................ 48

III. ANALYSIS ........................................................................................................................... 48

A. Use Characterization............................................................................................. 48

B. Exposure Characterization.................................................................................... 50
8

Environmental Fate and Transport Characterization ........................................... 50

Measures of Aquatic Exposure ............................................................................. 50

Aquatic Exposure Modeling...................................................................... 50

Measures of Terrestrial Exposure......................................................................... 54

Spray Drift Exposure ................................................................................. 54

Terrestrial Exposure Modeling.................................................................. 54

C. Ecological Effects Characterization....................................................................... 57

D. Aquatic Effects Characterization........................................................................... 61

Aquatic Animals .................................................................................................... 61

Acute Toxicity of HalauxifenͲmethyl......................................................... 67

Chronic Toxicity of HalauxifenͲmethyl...................................................... 68

Degradate Toxicity to Aquatic Animals..................................................... 70

Aquatic Plants ....................................................................................................... 72

Degradate Toxicity to Aquatic Plants.................................................................... 74

E. Terrestrial Effects Characterization ...................................................................... 77

Terrestrial Animals................................................................................................ 77

Birds 77

Mammals .................................................................................................. 80

Terrestrial Invertebrates........................................................................... 80

Terrestrial Plants....................................................................................... 83

F. Risk EstimationͲIntegration of Exposure and Effects Data ................................. 88

Aquatic Plants ....................................................................................................... 90

NonͲtarget Terrestrial Animals............................................................................. 90

NonͲtarget Terrestrial and SemiͲaquatic Plants................................................... 91

Formulation GFͲ2685................................................................................ 91

Ground Application....................................................................... 91

Aerial Application.......................................................................... 92

Spray Drift Distances and LOC exceedances................................. 92

Formulation GFͲ2687................................................................................ 96

Ground Application....................................................................... 96

Aerial Application.......................................................................... 97

Spray Drift Distances and LOC exceedances................................. 97

Terrestrial Plant Communities................................................................ 101

Contaminated Irrigation ......................................................................... 101

Contaminated Compost.......................................................................... 102

Analytical Methods................................................................................. 103

G. Risk Conclusions.................................................................................................. 104

IV. REFERENCES .................................................................................................................... 105

APPENDIX A. Studies Used in this Risk Assessment.................................................................... 106

APPENDIX B. Safener Data .......................................................................................................... 114

APPENDIX C. Kinetic Analysis...................................................................................................... 117

APPENDIX D. HalauxifenͲmethyl Transformation Product Summary......................................... 145

APPENDIX E. Summary of Total HalauxifenͲmethyl Residues.................................................... 153

APPENDIX F. Sample TͲREX Inputs and Outputs for the Proposed Uses of HalauxifenͲmethyl. 156
9

APPENDIX G. TerrPlant Inputs and Outputs for the Proposed HalauxifenͲmethyl Uses............ 160

APPENDIX H. Calculations for Potential Exposure from Residues in Irrigation Water............... 165

APPENDIX I. Spray Drift Analyses................................................................................................ 166

LIST OF FIGURES

Figure 1. Proposed HalauxifenͲmethyl Environmental Transformation Schemea ....................... 22

Figure 2. Conceptual Model Depicting Stressors, Exposure Pathways, and Potential Effects to

Aquatic Organisms from the Proposed Uses of HalauxifenͲmethyla............................................ 45

Figure 3. Conceptual Model Depicting Stressors, Exposure Pathways, and Potential Effects to

Terrestrial Organisms from the Proposed Uses of HalauxifenͲmethyla ....................................... 46

Figure 4. Wheat Growing Areas in the United States................................................................... 50

Figure 5. Tier III AgDrift Aerial Spray Drift Analysis for NonͲlisted Plants: GFͲ2685; the halauxifen

estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial plants

vegetative vigor IC25 endpoints (GFͲ2685 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines. ........................................ 93

Figure 6. Tier III AgDrift Aerial Spray Drift Analysis for Listed Plants: GFͲ2685; the halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC05 endpoints (GFͲ2685 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines. ........................................ 94

Figure 7. Tier I AgDrift Ground Spray Drift Analysis for NonͲlisted Plants: GFͲ2685; the

halauxifen estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial

plants vegetative vigor NOAC or IC05 endpoints (GFͲ2685 formulation; solid lines).

Concentrations exceed the endpoint to the left of the intersection of the dotted and solid lines.

....................................................................................................................................................... 95

Figure 8. Tier I AgDrift Ground Spray Drift Analysis for Listed Plants: GFͲ2685; the halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC05 endpoints (GFͲ2685 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines. ........................................ 96

Figure 9. Tier III AgDrift Aerial Spray Drift Analysis for NonͲListed Plants: GFͲ2687; The

halauxifen estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial

plants vegetative vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines).

Concentrations exceed the endpoint to the left of the intersection of the dotted and solid lines.

....................................................................................................................................................... 98

Figure 10. Tier III AgDrift Aerial Spray Drift Analysis for Listed Plants: GFͲ2687; The halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines. ........................................ 99

Figure 11. Tier I AgDrift Ground Spray Drift Analysis for NonͲlisted Plants: GFͲ2687; The

halauxifen estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial

plants vegetative vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines).
10

Concentrations exceed the endpoint to the left of the intersection of the dotted and solid lines.

..................................................................................................................................................... 100

Figure 12. Tier I AgDrift Ground Spray Drift Analysis for Listed Plants: GFͲ2687; The halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines. ...................................... 101

LIST OF TABLES

Table 1. HalauxifenͲmethyl End Use Product Summary for the United States............................ 16

Table 2. Proposed HalauxifenͲmethyl Application Rates ............................................................. 19

Table 3. Chemical Identification and Physical Chemical Properties for HalauxifenͲmethyl and

Halauxifen ..................................................................................................................................... 20

Table 4. Chemical Properties and Environmental Fate Parameters of HalauxifenͲmethyl.......... 23

Table 5. Chemical Properties and Environmental Fate Parameters of Halauxifen (XDEͲ7219 acid)

....................................................................................................................................................... 26

Table 6. Soil Mobility Data for XDEͲ729 acid and X11449757...................................................... 35

Table 7. Terrestrial Field Dissipation Data for HalauxifenͲmethyl................................................ 37

Table 8. Field Dissipation Reported Temperatures for HalauxifenͲmethyl.................................. 38

Table 9. Terrestrial Field Dissipation Data for XDEͲ729 acid ........................................................ 39

Table 10. Taxonomic Groups and Test Species Generally Used Evaluated for Ecological Effects in

ScreeningͲLevel Risk Assessments................................................................................................ 42

Table 11. Acute and Chronic Measures of Effect.......................................................................... 48

Table 12. National Harvest and Planted Statistics for Proposed HalauxifenͲmethyl Use Sites.... 49

Table 13. Input Parameters Used for Modeling HalauxifenͲmethyl Residues............................. 51

Table 14. Estimated Environmental Concentrations Based on the Proposed Use of HalauxifenͲ

methyl ........................................................................................................................................... 53

Table 15. Tier I Spray Drift Analysis: Offsite Concentrations (in lb a.i./acre) at Various Distances

Downwind From a Field Treated with HalauxifenͲmethyl Using Aerial Equipment..................... 55

Table 16. Tier I Spray Drift Analysis: Offsite Concentrations (in lb a.i./acre) at Various Distances

Downwind From a Field Treated with HalauxifenͲmethyl Using Ground Equipment.................. 55

Table 17. Estimate Concentrations on Potential Food Items Following LabelͲSpecified

Applications of HalauxifenͲmethyl Using the TͲREX Model ......................................................... 56

Table 18. Estimated Environmental Concentrations Derived from the TerrPlant Screening Model

....................................................................................................................................................... 56

Table 19. Summary of Specific Assessment Endpoints for Animals and Plants Considered in this

Assessment for Estimating Risks to NonͲtarget Taxaa .................................................................. 59

Table 20. Submitted Toxicity Data for HalauxifenͲmethyl and Aquatic Animals ......................... 61

Table 21. Submitted Toxicity Data for HalauxifenͲmethyl Transformation Products and Aquatic

Animals.......................................................................................................................................... 71

Table 22. Submitted Toxicity Data for HalauxifenͲmethyl and Aquatic Plants ............................ 72
11

Table 23. Submitted Toxicity Data for HalauxifenͲmethyl Transformation Products and Aquatic

Plants............................................................................................................................................. 74

Table 24. Submitted Toxicity Data for HalauxifenͲmethyl and Birds ........................................... 77

Table 25. Submitted Toxicity Data for HalauxifenͲmethyl and Transformation Products for

Terrestrial Invertebrates............................................................................................................... 81

Table 26. Terrestrial Plants Toxicity: Seedling Emergence for GFͲ2685 (lb a.e./A)a .................... 84

Table 27. Terrestrial Plants: Vegetative Vigor Toxicity Data for GFͲ2685a ................................... 84

Table 28. Summary of the Most Sensitive Endpoints for Formulation GFͲ2685a For RQ

Calculations................................................................................................................................... 85

Table 29. Terrestrial Plants: Vegetative Vigor Toxicity Data For GFͲ2686a .................................. 85

Table 30. Terrestrial Plants Toxicity: Seedling Emergence for GFͲ2687 (lb a.e./A)a .................... 86

Table 31.Terrestrial Plants Toxicity: Vegetative Vigor for GFͲ2687 (lb a.e./A)a ........................... 86

Table 32. Summary of the Most Sensitive Endpoints for Formulation GFͲ2687 For RQ

Calculations................................................................................................................................... 87

Table 33. Terrestrial Plants: Comparison of Submitted Seedling Emergence Toxicity Data for GFͲ

2685, GFͲ2687, XDEͲ729 acid, and X11449757 ............................................................................ 88

Table 34. Agency Levels of Concern (LOC).................................................................................... 89

Table 35. Aquatic Animal Risk Quotients for Exposure Estimates Provided in Table 14 ............. 89

Table 36. Aquatic Plant Risk Quotients for Exposure Estimates Provided in Table 14 ................ 90

Table 37. Risk Quotients for Plants and Endangered Terrestrial Plants for Ground and Aerial

Application of HalauxifenͲmethyl Formulation GFͲ2685.............................................................. 92

Table 38. Risk Quotients for Plants and Endangered Terrestrial Plants for Ground and Aerial

Application of HalauxifenͲmethyl Formulation GFͲ2687.............................................................. 97

Table 39. Analytical Method Comparison with Toxicity Endpoints for Formulation GFͲ2685... 103

LIST OF APPENDICES

APPENDIX A. Studies Used in this Risk Assessment.................................................................... 106

APPENDIX B. Safener Data .......................................................................................................... 114

APPENDIX C. Kinetic Analysis...................................................................................................... 117

APPENDIX D. HalauxifenͲmethyl Transformation Product Summary......................................... 145

APPENDIX E. Summary of Total HalauxifenͲmethyl Residues.................................................... 153

APPENDIX F. Sample TͲREX Inputs and Outputs for the Proposed Uses of HalauxifenͲmethyl. 156

APPENDIX G. TerrPlant Inputs and Outputs for the Proposed HalauxifenͲmethyl Uses............ 160

APPENDIX H. Calculations for Potential Exposure from Residues in Irrigation Water............... 165

APPENDIX I. Spray Drift Analyses................................................................................................ 166

 
12

I. EXECUTIVE SUMMARY 

A. Nature of Chemical Stressor

HalauxifenͲmethyl (also known as XDEͲ729 methyl; PC Code 117501) is a new herbicide

proposed for the postͲemergent control of annual broadleaf weeds such as lambsquarter,

redroot pigweed, cleavers, henbit, wild buckwheat, and mustards in barley, triticale, and wheat.

In addition to the technical product, four end use products [GFͲ2685, GFͲ2686, GFͲ2687, and

GFͲ2688] are proposed for registration in the United States. Three of the proposed end use

products contain additional active ingredients including fluroxypyr (PC code 128959) and

florasulam (PC Code 129108) and three of the four endͲuse products also include a safener.

HalauxifenͲmethyl may be applied as a foliar spray twice per year via aerial or ground

equipment at a maximum single application rate of 0.0091 lb active ingredient (a.i.)/acre or

0.0086 acid equivalents (a.e.)/acre and a maximum of 0.0182 lb a.i./A/year (0.0172

a.e./acre/year) according to the proposed label.

XDEͲ729 acid, a major environmental transformation product of halauxifenͲmethyl, is expected

to have herbicidal characteristics similar to halauxifenͲmethyl1. In addition, based on similar

chemical structures as well as available toxicity data, one other environmental transformation

product, X11406790, shows some herbicidal characteristics (similar toxicity to aquatic vascular

and terrestrial plants). X11449757 has not been shown to retain herbicidal characteristics.

Additional residues were also identified in the environmental fate studies that because

definitive structures were not determined cannot be ruled out as residues of concern

(additional discussion is provided in the Residues of Concern section below) to terrestrial

plants.

For all other taxa, XDEͲ729 acid is expected to have a similar toxicity profile to halauxifenͲ

methyl while X11406790 and X11449757 as well as the other environmental transformation

products are expected to be less toxic (see Residues of Concern section) when compared to

halauxifenͲmethyl.

HalauxifenͲmethyl is considered a picolinic acid2 (pyridine compound containing carboxyl side

chain at the 2Ͳposition) or pyridine herbicide. Similarly registered herbicides include

aminopyralid, clopyralid, and picloram.

1 Ovalle, D., Carranza, G. N. M., RojasͲCalvo, C. E., Paniagua, L., Reichert, A., Masters, R. A. Herbicidal Composition

Containing 4ͲaminoͲ3ͲchloroͲ6Ͳ(4ͲchloroͲ2ͲfluoroͲ3Ͳmethoxyphenyl) pyridineͲ2Ͳcarboxylic acid or Derivative

Thereof and Fluroxypyr or Derivatives Thereof. U.S. Patent Application US 13/705,899 (U.S. publication number

US20130143739), June 6, 2012. http://www.google.com/patents/US20130143739 (accessed 11/6/2013) 2 The methyl ester hydrolyses to the corresponding acid (referred to as halauxifen, halauxifenͲacid, XDEͲ729 acid).
13

B. ConclusionsͲExposure Characterization

Laboratory data suggest that halauxifenͲmethyl, a methyl ester, undergoes rapid

deesterification to the corresponding free acid (halauxifen; XDEͲ729 acid) following application

(representative3 aerobic soil halfͲlife values range from 1 to 2 days; aerobic aquatic halfͲlife

values range fromless than 1 to 5 days) and is considered moderately mobile. Due to

significant degradation of halauxifenͲmethyl in the adsorption and desorption equilibrium

experiment a sorption factor cannot be definitively determined for halauxifenͲmethyl. While

halauxifenͲmethyl is subject to both abiotic (aqueous photolysis and alkaline hydrolysis) and

biotic (metabolism) degradation, the corresponding acid, halauxifen (XDEͲ729 acid), is expected

to be more persistent and mobile, as are some of the other structurallyͲsimilar transformation

products. In the environment the acid is expected to be present as the anion (estimated pKa

5.11)4

. Aerobic soil metabolism halfͲlife values for XDEͲ729 acid range from 2 to 42 days while

the aerobic aquatic halfͲlife values range from 2Ͳ12 days. Koc values range from 28Ͳ423 mL/goc

for XDEͲ729 acid.

Field data suggest that halauxifenͲmethyl and XDEͲ729 acid are more persistent [dissipation

halfͲlife values ranged from less than 3 to 273 days (halauxifenͲmethyl) and 12 to 361 days

(halauxifen) in the environment than the laboratory studies testing the technical grade active

ingredient indicate.

The primary mechanisms of transport of halauxifenͲmethyl away from the treated field will be

spray drift, runoff, and leaching. HalauxifenͲmethyl is not considered volatile and, therefore, is

not likely prone to vapor phase atmospheric transport. XDEͲ729 acid will also runoff into water

bodies as well as leach through the soil profile. XDEͲ729 acid volatilization is not expected.

For all taxa the halauxifenͲmethyl and XDEͲ729 acid are considered residues of concern.

However, for terrestrial plants additional residues are considered of toxicological concern

including (X11406790, degradates 1, 2, 4, 10, 11, and 14). Based on toxicity data for XDEͲ729

acid and X11406790 these residues are expected to have similar toxicity to terrestrial plants. No

toxicity data are available for degradates 1, 2, 4, 10, 11, and 14 (structures were not definitively

determined) and; therefore, cannot be ruled out as residues of toxicological concern to

terrestrial plants. A total residue approach was employed to account for the potential toxicity

of these unidentified residues as well as the unextracted residues. These results are presented

for additional characterization.

For the aquatic exposure modeling, halauxifenͲmethyl and XDEͲ729 acid were modeled

separately. Peak estimated environmental concentrations (EECs) are expected to be no greater

than 0.15 μg/L (ppb) for halauxifenͲmethyl and 0.19 ppb for XDEͲ729 acid. In addition, aquatic

3 Standard Operating Procedure for Using the NAFTA Guidance to Calculate Representative HalfͲlife Values and

Characterizing Pesticide Degradation. March 23, 2015. http://www.epa.gov/sites/production/files/2015-

08/documents/ftt_sop_using_nafta_guidance_version2.pdf

4

MRID 48557711 (pka determined using UVͲVis at 21.9 °C)
14

exposure estimates were also calculated using a total residue approach taking into account

halauxifenͲmethyl, XDEͲ729 acid, X11449757, X11406790, degradates 1, 2, 4, 10, 11, and 14;

the peak is 1 ppb.

Since halauxifenͲmethyl is a new chemical, no monitoring data are available for the halauxifenͲ

methyl or its environmental transformation products.

C. ConclusionsͲEffects Characterization

HalauxifenͲmethyl is classified as moderately toxic to practically nonͲtoxic to freshwater and

estuarine/marine fish, freshwater amphibians, freshwater and estuarine/marine invertebrates,

birds, mammals, and terrestrial invertebrates on an acute exposure basis.

Chronic exposure studies for freshwater and estuarine/marine fish, amphibians and

invertebrates resulted in significant effects on survival, growth and reproduction. However,

based on the modeled estimated concentrations in water, no levels of concern (LOC) were

exceeded for these taxa.

Chronic effects in birds and mammals were also demonstrated with statistically significant

reductions in reproduction and growth for both taxa. However, the NOAECs for these studies

do not result in LOC exceedances based on the proposed labeled rates for wheat, barley and

triticale.

The most sensitive aquatic vascular plant tested with halauxifenͲmethyl was the Eurasian

watermilfoil, Myriophyllum spicatum, with an EC50 value of 0.000135 mg a.i./L and a IC05

0.00008 mg a.i./L (NOAEC <0.0000617 mg a.i./L) based on a reduction in total shoot length

yield. Results from another study with this taxon using XDEͲ729 acid derived similar endpoints.

NonͲvascular aquatic plants are much less sensitive to halauxifenͲmethyl and its environmental

transformation products than vascular aquatic plants.

Terrestrial plant toxicity studies were conducted with two end use product formulations, as

well as with the degradate XDEͲ729 acid. These studies provide a number of endpoints showing

that halauxifenͲmethyl formulations and XDEͲ729 acid are highly toxic to terrestrial plants from

the onset of seed germination through plant maturation phases captured in the seedling

emergence and vegetative vigor studies. The most sensitive monocot was onion in the seedling

emergence and vegetative vigor studies, with IC25 values of 0.000801 lb a.e/acre and 0.00128 lb

a.e./acre, respectively (NOAECs = 0.000557 and 0.000139 lb a.e./acre, respectively).

The dicot studies show sunflower, Helianthus annuus, to be the most sensitive species tested in

the seedling emergence studies with an IC25 = 0.000290 lb a.e./acre and a corresponding NOAEC

of 0.0000696 lb a.e./acre for reduced growth (height). In the vegetative vigor studies, the

soybean (Glycine max) was the most sensitive to the formulations. The IC25 for soybean was

0.0000102 lb a.e./acre based on reduced fresh weight, with a corresponding NOAEC of

0.00000872 lb a.e./acre.
15

D. Potential Risks to NonͲtarget Organisms

Risk to terrestrial and aquatic vascular plants is predicted with risk quotients ranging from 0.1

to 2474. However, risk to birds (and, thus, reptiles and terrestrialͲphase amphibians), fish (and,

thus, aquaticͲphase amphibians), mammals, aquatic nonͲvascular plants, terrestrial and aquatic

invertebrates is not expected from the proposed halauxifenͲmethyl uses.

E. Uncertainties

A large (up to 87% of the applied radioactivity) amount of unextracted residues were observed

in some of the environmental fate studies. The extraction procedures used are not considered

exhaustive. A minimal amount of unextracted residues (<10%) were observed in the sterile soils

studies (MRID 48557736). This suggests that the unextracted residues are the result of

metabolism and are associated with a transformation product. Additionally, variably low

recoveries of XDEͲ729 acid and X11449757 (the only two transformation products analyzed for)

were observed in the spiked soil samples supporting the terrestrial field dissipation, suggesting

the extraction procedures may have been optimized for halauxifenͲmethyl but not for the

corresponding environmental transformation products. Since a default halfͲlife value was used

in the terrestrial exposure modeling the risk assessment approach is expected to be reasonably

conservative for total residues. In addition, EECs that include unextracted residues are

presented.

HalauxifenͲmethyl is characterized as being moderately mobile; however, significant

degradation of halauxifenͲmethyl was observed during the adsorption and desorption

equilibrium experiment. Therefore, the mobility of halauxifenͲmethyl cannot be accurately

assessed. However, it is expected that halauxifenͲmethyl transformation products are more

mobile than halauxifenͲmethyl. Sorption data are available for XDEͲ729 acid and X11449757.

Use of the sorption factor from one of the transformation products in modeling may result in

the overestimation of the actual environmental concentrations of the methyl ester. However,

this may be countered by the underestimation of environmental concentrations due to the use

of model input values derived from laboratory data and used in exposure modeling that

indicate more rapid degradation, than observed in the field studies.

Reproductive risks to plants and effects to terrestrial plants from multiple applications are

currently not included in screeningͲlevel risk assessments, and thus are an uncertainty.

While a number of studies have been conducted on terrestrial plants, EPA has identified one

formulation (GFͲ2688; coͲformulated with fluroxypyr) where the U.S. patent claims a

“synergistic effect”.1 There is a potential for this formulation, GFͲ2688, to be more highly toxic

to terrestrial plants than the other formulations tested. The patent also claims “synergistic

effect” when used in combination with other currently registered herbicides which could be

used as a tank mix with halauxifenͲmethyl. Data to evaluate these claims are not available.
16

Current draft labels only include recommendations for minimizing spray drift and using nozzles

that ‘ensure medium or coarser spray.’ Based on the proposed label language, there is

uncertainty with the potential droplet size spectrum that may be generated resulting from

spray drift (aerial and ground). Therefore, a range of spray drift values were presented in this

assessment, ranging from fine to coarse droplet sizes (droplet sizes defined; see Table 15 and

Table 16).



II. PROBLEM FORMULATION

The purpose of this assessment is to evaluate the potential ecological risks for the proposed

new pesticide halauxifenͲmethyl (Methyl 4ͲaminoͲ3ͲchloroͲ6Ͳ(4ͲchloroͲ2ͲfluoroͲ3Ͳ

methoxyphenyl)pyridineͲ2Ͳcarboxylate; CAS. No.943831Ͳ98Ͳ9, PC Code: 117501).

A. Stressor Source and Distribution

Source and Intensity

HalauxifenͲmethyl is a new chemical proposed for registration by Dow AgroSciences (DAS). In

addition to the technical product, four end use products [GFͲ2685, GFͲ2686, GFͲ2687, and GFͲ

2688] are proposed for registration in the United States. Three of the proposed end use

products contain a combination of multiple active ingredients, including fluroxypyr and

florasulam as described in Table 1. In addition, three of the product end use products contain a

safener (see Table 1). Typically safeners are not assessed as part of a chemical specific risk

assessment; however, due to the high toxicity of halauxifenͲmethyl and the corresponding acid

to plants, it is briefly discussed in this assessment since the proposed application rates are

approximately equal to the IC25 for the proposed crops. Additional information on the safener is

provided in CONFIDENTIAL APPENDIX B.

Table 1. HalauxifenͲmethyl End Use Product Summary for the United States

Formulation

GFͲ2685 GFͲ2686 GFͲ2687 GFͲ2688

lb

a.i./gal

product

%

lb

a.i./gal

product

%

lb

a.i./gal

product

%

lb

a.i./gal

product

%

Active

Ingredients

HalauxifenͲ

methyl 0.10 10.4 0.10 10.5 0.21 20.9 0.14 1.6

Fluroxypyr ͲͲ ͲͲ ͲͲ ͲͲ ͲͲ ͲͲ 2.1 34.9

Florasulam ͲͲ ͲͲ 0.10 10.5 0.20 20 ͲͲ ͲͲ

According to the proposed label, the products would be used for the postͲemergent control of

annual broadleaf weeds such as lambsquarters, redroot pigweed, cleavers, henbit, wild

buckwheat, and mustards in barley, triticale, and wheat. HalauxifenͲmethyl would be applied as

a foliar spray via aerial or ground equipment.
17

Pesticide Type, Class, and Mode of Action

HalauxifenͲmethyl and the corresponding free acid, halauxifen (XDEͲ729 acid)5, are synthetic

auxin analogues in the picolinic acid (pyridine compound containing carboxyl side chain at the

2Ͳposition) class of herbicides. This herbicidal class includes picloram (4ͲaminoͲ3,5,6ͲtrichloroͲ

2Ͳpyridinecarboxylic acid; PC Code 005101), aminopyralid (4ͲaminoͲ3,6ͲdichloropyridineͲ2Ͳ

carboxylic acid; PC Code 005100), and clopyralid (3,6ͲdichloroͲ2Ͳpyridinecarboxylic acid; PC

Code 117403). The specific mechanism of action of these chemicals is not known. Auxins are

plant hormones that regulate a number of plant activities, including development of the plant

embryo, leaf formation, phototropism, gravitropism, apical dominance, fruit development,

abscission and root initiation. Auxins are actively transported into cells by a transmembrane

transporter protein, and leave the cells by facilitated diffusion through a different transporter

(Taiz and Zeiger, 2002). Based on studies of the auxin analogues 2,4ͲD and 2,4,5ͲT (neither of

which are pyridine carboxylic acids), it appears the import mechanism allows auxinic herbicides

into the cell, but the herbicides do not leave the cell through the exporter. Cellular effects

include alterations in cell wall elasticity and gene expression. Additionally, nonͲproductive

tissue growth is often induced, resulting in epinasty and phloem disruption, preventing the

movement of photosynthates and causing death in days to weeks (Thill, 2002).

Overview of Pesticide Usage

The proposed halauxifenͲmethyl use rates are presented in Table 2. The proposed application

rates are similar to use rates currently registered for aminopyralid. Other picolinic acid

herbicides such as picloram and clopyralid have much higher application rates.

Residues of Concern

Halauxifen, XDEͲ729 acid, is thought to be the primary or intended active ingredient while the

methyl ester or halauxifenͲmethyl is the carrier compound (also referred to as parent) which

also has herbicidal properties. Therefore, both of these compounds, halauxifenͲmethyl and the

corresponding free acid (XDEͲ729 acid) are considered active ingredients (or pesticides) in this

assessment. Depending on the taxa being assessed different residues are considered as

residues of concern. These residues are identified below by taxa. The safener was not

considered a residue of concern in this assessment.

Aquatic Animals

Both halauxifenͲmethyl and XDEͲ729 acid are residues of concern individually since both

residues are considered active ingredients. XDEͲ729 acid is expected to be the primary residue

of exposure in the environment; however, halauxifenͲmethyl was observed to be in some cases

three orders of magnitude more toxic to some taxa.

5 XDEͲ729 acid is expected to form via methyl ester hydrolysis or deesterification.
18

Aquatic Plants

Available toxicity data indicate halauxifenͲmethyl and XDEͲ729 acid are equally toxic to aquatic

vascular plants while X11406790 and X11449757 are less toxic. No toxicity data are available for

photolysis transformation products (degradates 1, 2, 4, 10, 11, and 14); however, exposure to

these compound is expected to be low. Low exposure is expected because all transformation

products except transformation products 10 and 11 are minor transformation products and are

only observed in the aquatic photolysis experiments. Aquatic photolysis is only expected to

occur on leaf surfaces and in shallow clear water. The structure of Degradate 10 has not been

confirmed but an exact mass was determined suggesting that one of the chlorine atoms in

halauxifenͲmethyl was replaced by a hydroxyl group. The structure of Degradate 11 was also

not confirmed; nevertheless, the exact mass determination suggests this compound no longer

retains the pyridine ring. Elimination of the pyridine ring is expected to change the binding

interaction with the target receptor; therefore, altering or eliminating the mode of toxicity.

Thus, Deg. 11 is not expected to retain herbicidal activity. For quantitative risk assessment

purposes the residues of concern for aquatic plants included in this assessment are halauxifenͲ

methyl and XDEͲ729 acid; however, for characterization purpose, a total residues approach was

employed to explore the potential risks associated with the aquatic photolysis transformation

products since toxicity data are not available for these unidentified residues.

Terrestrial Plants

For terrestrial plants, this assessment takes into account halauxifenͲmethyl and XDEͲ729 acid as

primary toxicants in the formulations.These residues are referred to as total halauxifenͲmethyl

residues. Seven additional transformation products (X11406790, degradates 1, 2, 4, 10, 11, and

14) may also be potential residues of concern, however, these are expected to have lower

toxicity and would occur in the environment at much lower concentrations than the parent and

acid chemicals.

It should be noted that the unextracted residues observed in the environmental fate soil

studies could not be ruled out as one of the transformation products mentioned above;

therefore, these residues cannot be ruled out as a transformation product of toxicological

concern. Additional analyses were conducted that includes the unextracted residues as residues

of concern.
19

Table 2. Proposed HalauxifenͲmethyl Application Rates

Crop/Site

Residential

Agricultural

ForestryTiming; Application Type Method/ Equipment

Maximum

Single

Application

Rate by

Formulation

(a.i. lb/A)a

Maximum

Application

Rate

Maximum

Application

Number

(days) PHI

d

(hours) REI

d

(days) MRI

d

Geographic

Restrictions Comments Per Yeara

lb/A

Per

CCa,c

lb/A

Per

Year

Per

CCb

Barley,

Triticale,

Wheat

3

PostͲ

emergence

foliar

Broadcast/

Ground

Aerial

0.0091b

(4.1 g/A) 0.018 0.0091 2 1 60 12 ns ns

Label: GFͲ2685Ͳ One application at

0.0091 lb a.i./A or two applications at

less than 0.0091 lb a.i./A may beapplied 10 days apart; however, the

total seasonal application rate cannot

exceed the maximum seasonal

application rate. Labels: GFͲ2686 and

GFͲ2687ͲA minimum retreatment

interval is not specified on the label;

however, only one application rate is

specified on the label which is equal to

the maximum seasonal application rate.

Label: GFͲ2688ͲA minimum

retreatment interval is not specified on

the label.

a. Application rate provided on the label is in terms of halauxifen (0.0086 acid equivalents (a.e.) lb/A. The values provided in the table are for parent, halauxifenͲmethyl

b. maximum application rate calculations:

GFͲ2685Ͳ ͲǤͲͲͻͳ݈ܾ ݄݈ܽܽݔݑ݂݅݁݊Ͳ݉݁ݐ݄ݕ݈ ܣൗ ൌ  ଴Ǥଵ௟௕ଡ଼ୈ୉ି଻ଶଽୟୡ୧ୢ ଵ௟௕GFͲ2685 ൈ  ଵ௟௕GFͲ2685 ଵ଺௢௭GFͲ2685 ൈ ଵǤସ௢௭GFͲ2685 ஺ ൈ ଷସହǤଵ଺g mol halauxifenͲmethyl ൗ ଷଷଵǤଵଷg mol XDEͲ729 acid ൗ

GFͲ2686 Ͳ ͲǤͲͲͶͻ݈ܾ ݄݈ܽܽݔݑ݂݅݁݊Ͳ݉݁ݐ݄ݕ݈ ܣൗ ൌ  ଴Ǥଵ௟௕ଡ଼ୈ୉ି଻ଶଽୟୡ୧ୢ ଵ௟௕GFͲ2686 ൈ ଵ௟௕GFͲ2686 ଵ଺௢௭GFͲ2686 ൈ ଴Ǥ଻ହ௢௭GFͲ2686 ஺ ൈ ଷସହǤଵ଺g mol halauxifenͲmethyl ൗ ଷଷଵǤଵଷg mol XDEͲ729 acid ൗ

GFͲ2687 Ͳ ͲǤͲͲͶͻ݈ܾ ݄݈ܽܽݔݑ݂݅݁݊Ͳ݉݁ݐ݄ݕ݈ ܣൗ ൌ  ଴Ǥଶ௟௕ଡ଼ୈ୉ି଻ଶଽୟୡ୧ୢ ଵ௟௕GFͲ2687 ൈ ଵ௟௕GFͲ2687 ଵ଺௢௭GFͲ2687 ൈ ଴Ǥଷ଻ହ௢௭GFͲ2687 ஺ ൈ ଷସହǤଵ଺g mol halauxifenͲmethyl ൗ ଷଷଵǤଵଷg mol XDEͲ729 acid ൗ

GFͲ2688 Ͳ ͲǤͲͲ͸ͳ݈ܾ ݄݈ܽܽݔݑ݂݅݁݊Ͳ݉݁ݐ݄ݕ݈ ܣൗ ൌ  ଴Ǥଵଷହ௟௕ଡ଼ୈ୉ି଻ଶଽୟୡ୧ୢ ଵ௚௔௟GFͲ2688 ൈ ଵ௚௔௟GFͲ2688 ଵଶ଼௢௭GFͲ2688 ൈ ହǤହ௢௭GFͲ2688 ஺ ൈ ଷସହǤଵ଺g mol halauxifenͲmethyl ൗ ଷଷଵǤଵଷg mol XDEͲ729 acid ൗ

c. Reported as per crop cycle or per season

d. PHI – Preharvest interval; REI – Reentry interval; MRI – Minimum retreatment interval
20

Physical/Chemical/Fate and Transport Properties

The chemical structure of halauxifenͲmethyl and halauxifen along with the chemical

identification and physicalͲchemical properties are provided in Table 3. Based on the reported

vapor pressure of halauxifenͲmethyl it is not expected to be volatile or prone to vapor phase

atmospheric transport.

Table 3. Chemical Identification and Physical Chemical Properties for HalauxifenͲmethyl and

Halauxifen

Common

Chemical Name halauxifenͲmethyl halauxifen or halauxifen acid

IUPAC Chemical

Name

Methyl 4ͲaminoͲ3ͲchloroͲ6Ͳ(4ͲchloroͲ2Ͳ

fluoroͲ3Ͳmethoxyphenyl)pyridineͲ2Ͳ

carboxylate

4ͲAminoͲ3ͲchloroͲ6Ͳ(4ͲchloroͲ2ͲfluoroͲ3Ͳ

methoxyphenyl)pyridineͲ2Ͳcarboxylic acid

CAS Chemical

Name

2ͲPyridinecarboxylic acid, 4ͲaminoͲ3ͲchloroͲ6Ͳ

(4ͲchloroͲ2ͲfluoroͲ3Ͳmethoxyphenyl)Ͳ, methyl

ester

2ͲPyridinecarboxylic acid, 4ͲaminoͲ3ͲchloroͲ6Ͳ(4Ͳ

chloroͲ2ͲfluoroͲ3Ͳmethoxyphenyl)

Company Code XDEͲ729 methyl

X11393729

X’729

XDEͲ729 acid

Chemical

Structure

Chemical

Abstracts Service

(CAS) Registry

Number

943831Ͳ98Ͳ9 943832Ͳ60Ͳ8

Molecular

Formula C14H11Cl2FN2O3 C13H9Cl2FN2O3

Smiles Notation C1(=C(C(=CC=C1C2=NC(=C(C(=C2)N([H])[H])Cl)

C(=O)OC)Cl)OC)F COc1c(ccc(c1F)c2cc(c(c(n2)C(=O)O)Cl)N)Cl

Molecular Mass 345.16 g/mol 331.13 g/mol

Vapor Pressure

(25 °C)

1.5 x 10Ͳ8 Pa

(1.1 x 10Ͳ10 mm Hg)a 1.8 x 10Ͳ9 mm Hg

Water Solubility 1.66Ͳ1.69 mg/L at 20 °C for pH 5, 7, 9;

1.83 mg/L at 20 °C for purified waterb

102 mg/L at 20°C for pH 5

3.1 g/L 20°C for pH 7

46.1 g/L 20°C pH 9

84.0 mg/L at 20°C for purified watere

Henry’s Law

Constant 1.22 x 10Ͳ6 Pa m3

/molc  1.46 x 10Ͳ16 atm m3/mol (bond method EPI Suite)
21

(1.2 x 10Ͳ11 atm m3/mol; 6.1 x 10Ͳ11 atm

m3

/molf)

Log Kow 3.75Ͳ3.92 for pH 5, 7, 9d 0.42 pH 5,Ͳ0.83 pH 7,Ͳ1.01 pH 9g

pKa 2.8h 5.11i

a. MRID 48557727

b.MRID 48557723

c. MRID 48557869

d.MRID 48557717

e. MRID 48557721

f. Calculated based on vapor pressure at 25 °C and solubility at 20 °C.

g. MRID 48557716

h.MRID 48557715

i. MRID 48557711 (22 °C)

Environmental fate parameters of halauxifenͲmethyl and halauxifen are presented in Table 4

and Table 5. A discussion of each environmental fate parameter is provided below for

halauxifenͲmethyl and XDEͲ729 acid. HalfͲlife values referenced in the sections below are the

halfͲlife values unless otherwise specified. The halfͲlife values are consistent with the NAFTA

kinetics guidance.6 Kinetic analyses are provided in APPENDIX C.

The proposed halauxifenͲmethyl environmental transformation scheme is presented in Figure 1

and includes several transformation products including: XDEͲ729 acid (halauxifen; X11393729),

X11406790, X11449757, degradates 1, 2, 4, 107, 118, and 14).Major transformation products

are shown in bold font in Figure 1. Maximum observed concentrations of transformation

products are provided in APPENDIX D as well as a full list of chemical code names and

synonyms for each compound. For characterization, environmental fate properties for total

residues (same residues as identified by the Health Effects Division as residues of toxicological

concern) are provided in APPENDIX E.

Degradation

Hydrolysis

HalauxifenͲmethyl hydrolysis is pH dependent (MRID 48557729). Hydrolysis occurs faster under

basic (higher pHs) conditions than acidic conditions. The estimated hydrolysis halfͲlives for

halauxifenͲmethyl at pH 4, 7, and 9 are approximately 81 days9

, 155 days9, and 3 days,

respectively.

6 Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media Health Canada, U.S.

Environmental Protection Agency, December 21, 2012. 7 A definitive chemical structure was not determined; however, the applicant proposed structures for these

transformation products as shown in Figure 1. 8 Proposed structure 9 HalfͲlife value is much longer than the study duration (i.e., 30 days)
22

The only transformation product observed is the corresponding free acid (for pH7, XDEͲ729 acid

was observed at a maximum concentration of 13% at the final interval), which was produced

quantitatively at each pH condition during the 30Ͳday study as a result of ester hydrolysis. This

suggests that XDEͲ729 acid is stable to hydrolysis; therefore, XDEͲ729 acid and total halauxifenͲ

methyl residues are assumed to be stable to hydrolysis.

Figure 1. Proposed HalauxifenͲmethyl Environmental Transformation Schemea



a. Major transformation products are shown in bold font.
23

Table 4. Chemical Properties and Environmental Fate Parameters of HalauxifenͲmethyl

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Guideline/

Source/

Classification

Comments

DT50 (days) DT90 (days)

Hydrolysis

pH 4, 25°C 81 269 Not applicable 835.2010

MRID

48557729

Acceptable

pH 7, 25°C 155 516 155 The only transformation product observed was XDEͲ729 acid.pH 9, 25°C 3 10 Not applicable

Aqueous

Photolysis pH 7, 25qC <10 minutes Not determinable SFO DT50=0.003

835.2240

MRID

48557731

Supplemental

Several HPLC peaks believed to be polar

compounds were found in the irradiated pH 7

buffer and natural water samples at >10% of the

applied; no attempts were made to identify these

compounds.

Soil Photolysis

Silt loam soil

(28qC, pH 5.9,

6.2% OM)

Not

determinable

Not

determinable Not applicable

835.2410

MRID

48557734

Supplemental

Due to the rapid degradation in the dark control

(faster than the irradiated samples)

phototransformation of halauxifenͲmethyl in soil

could not be appropriately assessed as a route of

dissipation under the conditions used in this

study.

Aerobic Soil

Metabolism

California

Clay loam soil

(20 qC, pH 7.1

2.2% OM)

2.13 (IORE) 17.5 (IORE) TIORE=5.27

835.4100

MRID

48557735

Supplemental

Per treatment type, only single samples were

collected at each sampling interval.

The extraction methods are not considered

exhaustive. Unextracted residues were detected

atш10% of the applied and were not

characterized. Extraction procedures included

either CaCl2 equilibration overnight or

methanol:water (80:20) along with accelerated

solvent extraction method using methanol:water.

Sample results where recoveries were <88% or

>110% of the applied were omitted from the

study report.

Unextracted residues generally increased

throughout the study and accounted for up to

Germany

Loam soil

(20 qC, pH 5.0, 4.3% OM)

1.43 (IORE) 5.35 (IORE) TIORE=1.61

United Kingdom Silt loam

soil (20 qC, pH 5.9, 6.2%

OM)

1.27 (IORE) 6.52 (IORE) TIORE=1.96

United Kingdom Sandy

loam soil (20 qC, pH 7.5,

2.4% OM)

1.08 (SFO) 3.59 (SFO) t1/2=1.08
24

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Guideline/

Source/

Classification

Comments

DT50 (days) DT90 (days)

87% (day 62) of the applied radioactivity. All

unextracted [14C] residues, which were detected

atш10% of the applied, were not characterized. A

minimal amount of unextracted residues (<10%)

were observed in the sterile soils studies (MRID

48557736). This suggests that the unextracted

residues are the result of metabolism and are

associated with a transformation product.d

Calculated halfͲlives for sterile soils (MRID

48557736) ranged from 7.5Ͳ14 days underaerobic conditions. The sterility of the soil was

not confirmed; however, the only transformation

product formed was XDEͲ729 acid (hydrolysis

product). Although the hydrolysis halfͲlife at pH 7

is estimated to be 155 d, the observed

transformation in the sterile soils at pH 7.5 is

likely a result of hydrolysis. This likely occurred as

a result of soil mediated hydrolysis from residual

materials such as enzymes leached from

microorganisms following gamma radiation or

clay within the soil.

Anaerobic Soil

Metabolism

California Clay loam soil

flooded with HPLC grade

water (20qC, pH 7.1)

2.75 (IORE) 23.6 (IORE) TIORE=7.1

835.4200

MRID

48557736

Supplemental

The extraction methods are not considered

exhaustive and unextracted residues detected at

ш10% of the applied were not characterized.

Unextracted residues generally increased

throughout the study and accounted for up to

64.8% (123 d) of the applied radioactivity.

The anaerobic soil metabolism experiment wasconducted for an insufficient length of time as the

formation and decline of transformation products

was not observed.

Germany Loam soil

flooded with HPLC grade

water (20qC, pH 5.0)

1.23(IORE) 10.3 (IORE) TIORE=3.09

United Kingdom Silt loam

soil flooded with HPLC

grade water (20qC, pH 5.9)

0.935 (SFO) 3.11 (SFO) t1/2=0.935

United Kingdom Sandy

loam soil flooded with

HPLC grade water

1.43(IORE) 13.5 (IORE) TIORE=4.07
25

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Guideline/

Source/

Classification

Comments

DT50 (days) DT90 (days)

(20qC, pH 7.5)

Aerobic

Aquatic

Metabolism

England lake water:loamy

sand sediment (20qC,

water pH 7.0,

sediment pH 5.8)

5.01 (SFO) 16.7 (SFO) t1/2=5.01

835.4300

MRID

48557738

supplemental

The extraction methods are not considered

exhaustive and unextracted [14C]residues were

detected atш10% of the applied.

Per treatment type, only single samples were

collected at each sampling interval.

For the silt loam sediment system, the sampling

intervals were inadequate to accurately calculate

a dissipation halfͲlife for parent halauxifenͲ

methyl.

England lake water:silt

loam sediment (20qC,

water pH 8.3,

sediment pH 7.7)

0.848 (IORE) 3.03(IORE) TIORE=0.91

Anaerobic

Aquatic

Metabolism

North Dakota river

water:clay loam sediment

(20qC, water pH 8.2,

sediment pH 8.1)

0.54 (SFO) 1.8 (SFO) t1/2=0.54 834.4400

MRID

117501

Supplemental

Wyoming natural

water:sandy clay loam

sedimentc (20qC, water pH

8.2, sediment pH 8.3)

1.01 (IORE) 9.22 (IORE) TIORE=2.78c

Terrestrial Field

Dissipation

Site 1: New Jersey, Penn

soil series, Silt loam, pH

6.9

1.54 (DFOP) 32.4 (DFOP) Slow t1/2=13.6

835.6100

MRID

49022101

Supplemental

Observed DT50 <1 d; Observed DT90 =16 d

Site 2: Ontario, Fox soil

series, Sandy loam, pH 6.1 2.65 (IORE) 19.3 (IORE) TIORE=2.78 Observed DT50 =1.8 d; Observed DT90 =21 d

Site 3: Manitoba,

Neuhorst soil series, Clay

loam, pH 7.8

14.8 (IORE) 908 (IORE) TIORE=273 Observed DT50 =16.8 d; Observed DT90 =413 d

Site 4: Saskatchewan,

Elstow soil series, Clay

pH 7.6

9.92 (IORE) 407 (IORE) TIORE=122 Observed DT50 =10.8 d; Observed DT90 =355 d
26

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Guideline/

Source/

Classification

Comments

DT50 (days) DT90 (days)

Site 5: Alberta, Angus

Ridge and Camrose soil

series, Bare plot: Loam,

pH 6.1

4.02 (IORE) 175 (IORE) TIORE=52.6 Observed DT50 =4.7 d; Observed DT90 =321 d

Site 5: Alberta, Angus

Ridge and Camrose soil

series, Cropped plot:

Sandy clay loam

pH 7.3

5.4 (DFOP) 42.3 (DFOP) Slow t1/2=16 Observed DT50 =5.3 d; Observed DT90 =173 d

Site 6: North Dakota,

GlyndonͲTiffany soil series,

Bare plot:

Sandy loam, pH 6.7

9.41 (DFOP) 482 (DFOP) Slow t1/2=250 Observed DT50 =9.8d ; Observed DT90 =beyond the scope of the data set.

Site 6: North Dakota

GlyndonͲTiffany soil series,

Cropped plot:

Sandy loam, pH 6.5

6.46 (IORE) 330 (IORE) TIORE=99.4 Observed DT50 =5.1 d; Observed DT90 =362 d

a. DT50 and DT90 values were calculated using single firstͲorder (SFO), double firstͲ order in parallel (DFOP), or indeterminateͲ order equation (IORE). For DFOP, the

overall DT50 and DT90 are reported when available. The equations can be found in the document, Standard Operating Procedure for Using the NAFTA Guidance to

Calculate Representative HalfͲlife Values and Characterize Pesticide Degradation, U.S. Environmental Protection Agency, March 23, 2015

b. The value used to estimate a model input value is the calculated SFO DT50, TIORE, or the 2nd DT50 from the DFOP equation. The model chosen is consistent with that

recommended using the, Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media, Health Canada, U.S. Environmental Protection Agency,

December 21, 2012. The same model used to estimate the value used to derive a model input, is used to describe the DT50 and DT90 results.

c. Data for day three are inconsistent; see graph in DER

Table 5. Chemical Properties and Environmental Fate Parameters of Halauxifen (XDEͲ7219 acid)

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Source/

Classification

Comments

DT50 (days) DT90 (days)

Hydrolysis pH 4, 25°C No substantial degradation was observed 835.2010
27

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Source/

Classification

Comments

DT50 (days) DT90 (days)

pH 7, 25°C

MRID

48557729

Acceptable

The only transformation product observed was

XDEͲ729 acid (X11393729); therefore, XDEͲ729 is

assumed to be stable to hydrolysis.

pH 9, 25°C

Aqueous

Photolysis

pH 7, 25qC

(natural water)

0.02 (SFO)

(29 min)

97 (SFO)

(97 min)

t1/2=0.02

(29 min)

835.2240

MRID

48557731

Supplemental

XDEͲ729 acid (X11393729) was not observed to

form in the pH 7 buffer system; however, it was

observed to form in the natural water system and

XDEͲ729 acid formation increased overtime in the

dark control (assumed stable). The halfͲlife value

reported is based on the results from the natural

water test system.

Soil Photolysis

Silt loam soil

(28qC, pH 5.9,

6.2% OM)

Could not be determined; assumed to be stable

835.2410

MRID

48557734

Supplemental

See Table 4.

Aerobic Soil

Metabolism

California

Clay loam soil

(20oC, pH 7.1

2.2% OM)

19.5 (IORE) 138 (IORE) TIORE=41.6

835.4100

MRID

48557735

Supplemental

Germany

Loam soil

(20oC, pH 5.0, 4.3% OM)

3.3 (SFO) 11 (SFO) t1/2=3.3

IORE was the selected as the model following the

NAFTA kinetics guidance using the PestDF tool;

however, SFO was selected using best profession

judgement because the halfͲlife was a more

conservative value and the IORE C0 parameter

used in the model fitting was 179 which is much

higher than the initial concentration. See

APPENDIX C.

United Kingdom Silt loam

soil (20oC, pH 5.9, 6.2%

OM)

5.1 (IORE) 28.4 (IORE) TIORE=8.54
28

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Source/

Classification

Comments

DT50 (days) DT90 (days)

United Kingdom Sandy

loam soil (20oC, pH 7.5,

2.4% OM)

8.8 (IORE) 52 (IORE) TIORE=15.6

Anaerobic Soil

Metabolism

California Clay loam soil

flooded with HPLC grade

water (20oC, pH 7.1)

102 (SFO) 340 (SFO) t1/2=102

835.4200

MRID

48557736

Supplemental

Data used in this kinetic analysis are from 14 days

after flooding to study termination (121 days)

Germany Loam soil

flooded with HPLC grade

water (20oC, pH 5.0)

19.1(IORE) 77.4 (IORE) TIORE=23.3 Data used in this kinetic analysis are from 2 days after flooding to study termination (121 days)

United Kingdom Silt loam

soil flooded with HPLC

grade water (20oC, pH 5.9)

15.2 (SFO) 50.6 (SFO) t1/2=15.2 The IORE N parameter value is less than one. Selected SFO as the model (see APPENDIX C

United Kingdom Sandy

loam soil flooded with

HPLC grade water

(20oC, pH 7.5)

107 (SFO) 355 (SFO) t1/2=107 Data used in this kinetic analysis are from 6 days after flooding to study termination (121 days)

Aerobic

Aquatic

England lake water:loamy

sand sediment (20oC,

water pH 7.0,

sediment pH 5.8)

11.6 (SFO) 38.6 (SFO) t1/2=11.6 835.4300

MRID

48557738

supplemental

England lake water:silt

loam sediment (20oC,

water pH 8.3,

sediment pH 7.7)

3.0 (SFO) 9.9 (SFO) t1/2=3.0

Anaerobic

Aquatic

North Dakota river

water:clay loam sediment

(20oC, water pH 8.2,

sediment pH 8.1)

3.7 (SFO) 12.4 (SFO) t1/2=3.7 834.4400

MRID

48557739

Supplemental

Wyoming natural

water:sandy clay loam

sedimentc (20oC, water pH

8.2, sediment pH 8.3)

4.4 (SFO) 14.6 (SFO) t1/2=4.4
29

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Source/

Classification

Comments

DT50 (days) DT90 (days)

Terrestrial Field

Dissipation

Site 1: New Jersey, Penn

soil series, Silt loam, pH

6.9

12.4 (SFO) 41.3 (SFO) t1/2=12.4

835.6100

MRID

49022101

Supplemental

Observed DT50 =14.4 d; Observed DT90 =50 d

Site 2: Ontario, Fox soil

series, Sandy loam, pH 6.1 11.5 (SFO) 38.1 (SFO) t1/2=11.5 Observed DT50 =11.5 d; Observed DT90 =55 d

Site 3: Manitoba,

Neuhorst soil series, Clay

loam, pH 7.8

184 (SFO) 612 (SFO) t1/2=184 Observed DT50 =255 d; Observed DT90 beyond the scope of the data set.

Site 4: Saskatchewan,

Elstow soil series, Clay

pH 7.6

361 (SFO) 1200 (SFO) t1/2=361

The IORE N parameter value is less than one.

Selected SFO as the model (see APPENDIX E.

Observed DT50 =316 d; Observed DT90 beyond the

scope of the data set.

Site 5: Alberta, Angus

Ridge and Camrose soil

series, Bare plot: Loam,

pH 6.1

21.1(IORE) 1000 (IORE) TIORE=301 Observed DT50 =23 d; Observed DT90 beyond the scope of the data set.

Site 5: Alberta, Angus

Ridge and Camrose soil

series, Cropped plot:

Sandy clay loam

pH 7.3

17.2 (DFOP) 490 (DFOP) Slow t1/2=244 Observed DT50 =17.4 d; Observed DT90 beyond the scope of the data set.

Site 6: North Dakota,

GlyndonͲTiffany soil series,

Bare plot:

Sandy loam, pH 6.7

409 (SFO) 1359 (SFO) t1/2=409 Observed DT50 =357 d; Observed DT90 beyond the scope of the data set.

Site 6: North Dakota

GlyndonͲTiffany soil series,

Cropped plot:

Sandy loam, pH 6.5

214 (SFO) 709 (SFO) t1/2=214 Observed DT50 =291 d; Observed DT90 beyond the scope of the data set.
30

Study

System Name/

Characteristics

Kinetic Model Fitteda Value

and Unit (Fitting Equation)

HalfͲlife Value

Used to Derive Model

Input Values (days)bͲͲ

Source/

Classification

Comments

DT50 (days) DT90 (days)

a. DT50 and DT90 values were calculated using single firstͲorder (SFO), double firstͲ order in parallel (DFOP), or indeterminateͲ order equation (IORE). For DFOP, the overall

DT50 and DT90 are reported when available. The equations can be found in the document, Standard Operating Procedure for Using the NAFTA Guidance to Calculate

Representative HalfͲlife Values and Characterize Pesticide Degradation, U.S. Environmental Protection Agency, March 23, 2015.

b. The value used to estimate a model input value is the calculated SFO DT50, TIORE, or the 2nd DT50 from the DFOP equation. The model chosen is consistent with that

recommended using the, Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media, Health Canada, U.S. Environmental Protection Agency,

December 21, 2012. The same model used to estimate the value used to derive a model input, is used to describe the DT50 and DT90 results.

c. Data for day three are inconsistent; see graph in DER
31

Aquatic Photolysis

Aquatic photolysis of halauxifenͲmethyl was investigated in pH 7 buffered and natural water

solutions (MRID 48557731). The estimated environmentally relevant halfͲlife for halauxifenͲ

methyl is less than 10 minutes for both test systems.

Several transformation products were observed to form as a result of photolysis. The chemical

structures of the transformation products including a minor transformation product X11861662

(buffered and natural water) and a major transformation product XDEͲ729 acid (natural water),

were identified. For some of the other transformation products, the chemical structures were

proposed by the study author based on an exact mass determination; however, they were not

definitively determined (proposed structures are shown in Figure 1). These transformation

products, except XDEͲ729 acid, may be unique photolysis transformation products. Four of the

unresolved (i.e., structures not determined) transformation products [degradate 1, degradate

10 (Deg. 10), degradate 11 (Deg. 11), and degradate 14) were isolated individually at

concentrations greater than 10% of the applied radioactivity. The exact mass for Deg. 10

suggests that one of the chlorine atoms in halauxifenͲmethyl was replaced by a hydroxyl group.

The exact mass for Deg.11 indicates that Deg. 11 may no longer retain the pyridine ring.

Formation of XDEͲ729 in the natural water test system and lack of formation of XDEͲ729 acid in

the buffered system suggests that XDEͲ729 acid forms via microbial mediated processes and is

not a photolysis product. Since hydrolysis (155 day halfͲlife at pH 7) is much slower than aquatic

photolysis (10 minute halfͲlife) it is not usual that the formation of XDEͲ729 was not observed in

the buffered test system. Since XDEͲ729 acid was not observed to form in the buffered test

system aquatic photolysis of XDEͲ729 acid could not be adequately assessed for this test

system. In the natural water system, XDEͲ729 acid was observed to form at a maximum

observed concentration of 10.7% of the applied radioactivity at 0.003 days and it was not

detected at study termination. In addition, the dark control shows an increasing amount of

XDEͲ729 acid with the maximum concentration observed at study termination. This suggests

that when XDEͲ729 acid is formed by microbial mediated processes in the natural water, it is

susceptible to aquatic photolysis. Assuming that XDEͲ729 acid is stable to microbial mediated

degradation (dark control) on the time scale relevant to the aquatic photolysis study the

estimated environmentally relevant halfͲlife for XDEͲ729 acid is approximately 30 minutes10

based on the natural water system.

Total halauxifenͲmethyl residues were observed to degradate with a halfͲlife of 38.4 days. This

halfͲlife value was calculated for total halauxifenͲmethyl residues by subtracting out the carbon

dioxide (CO2) formation from the total applied radioactivity (t0) for each sampling interval. This

was done because the summation approach for calculating dissipation kinetics for the total

residues did not result in a good model fit or a reasonable halfͲlife value. This approach

assumes that all radioactivity material that is not CO2 is a residue of concern. Photolysis is only

10 k = 44.3; t1/2 = 0.0157 day (22.6 min) adjusted by 1.3 for use of artificial light source.
32

likely to occur in clear shallow surface water and on foliar surfaces. Taken together, aquatic

photolysis is not likely to be a major dissipation route for total halauxifenͲmethyl residues in the

environment.

Soil Photolysis

Rapid halauxifenͲmethyl transformation was observed in the dark control (faster than the

irradiated samples); therefore, the phototransformation of halauxifenͲmethyl in soil could not

be appropriately assessed as a route of dissipation (MRID 48557734). HalauxifenͲmethyl is

assumed to be stable to soil photolysis or at least photolysis is expected to be slower than

aerobic soil metabolism. The reported transformation products, XDEͲ729 acid and X11449757,

observed in the irradiated samples are also reported in the soil metabolism studies (i.e., no

unique phototransformation products were observed). More than 10% of the applied

radioactivity was reported as unextracted residues and less than 5% carbon dioxide was

observed to form. The formation of XDEͲ729 acid is increasing with time in both the irradiated

as well as the dark control experiments; therefore, phototransformation of halauxifen XDEͲ729

acid could not be assessed and is assumed to be stable to soil photolysis.

Soil photolysis is not expected to be an important route of dissipation for halauxifenͲmethyl or

its environmental transformation products in the environment.

Aerobic Soil Metabolism

HalauxifenͲmethyl was observed to transform rapidly under aerobic soil metabolism conditions

(MRID 48557735). HalfͲlife values ranged from 1.1 days to 5.3 days. HalauxifenͲmethyl was also

observed to transform (halfͲlife values ranged from 7.5Ͳ14 d) in sterile soils. Only one

transformation product (XDEͲ729 acid; a product of hydrolysis or deesterification) was

observed. Transformation of halauxifenͲmethyl in the sterile controls was likely the result of soil

mediated hydrolysis from residual materials such as enzymes leached from microorganisms

following gamma radiation or clay within the soil; however, soil surface mediated hydrolysis

cannot be ruled out. Alternatively, it is possible that the soil was not properly sterilized.

Four transformation products were identified in the soil metabolism studies: XDEͲ729 acid,

X11449757, X11406790, and CO2. All transformation products except X11406790 were isolated

at concentrations greater than 10% of the applied radioactivity in at least one soil system

studied and are more persistent than halauxifenͲmethyl.

In the environment, the acid is expected to be present as the anion (estimated pKa 5.11)11. The

halfͲlife values for XDEͲ729 acid ranged from 2 to 42 days (Table 5).

11 MRID 48557711 (pka determined using UVͲVis at 21.9 °C)
33

Across the four soils tested the maximum amount of CO2 formed ranged from 0 to 26%. An

increasingly large (up to 87% of the applied radioactivity) amount of unextracted residues were

observed in all studies. The extraction procedures used in the aerobic soil metabolism study

were not considered exhaustive. A minimal amount of unextracted residues (<10%) were

observed in the sterile soils studies (MRID 48557736). This suggests that the unextracted

residues are the result of metabolism and are associated with a transformation product.

However, the unextracted residues are not expected to be halauxifen, since the unextracted

residue concentration is low and the concentration of halauxifen is high, suggesting halauxifen

was effectively extracted.

Extraction efficiencies for the transformation products were not provided as part of the aerobic

soil metabolism data; however, spiked sample recoveries supporting the terrestrial field

dissipation studies (MRID 49022101) indicate that the extraction procedures used in the soil

studies may result in low recoveries (~50%) of the transformation products (i.e., XDEͲ729 acid

and X11449757). Moreover, the soil photolysis dark control experiment (MRID 48557734)

suggests the formation of unextracted residues is concurrent with the formation of X11449757.

Without additional information on the identification of these residues the unextracted residues

cannot be ruled out as potential transformation products of concern.



Total halauxifenͲmethyl residues (i.e., extracted toxic residues) were observed to degradate

with halfͲlife values ranging from 11 to 41 days with the maximum halfͲlife value approximately

equal to the maximum halfͲlife values calculated for XDEͲ729 acid. When unextracted residues

are considered as part of the total residues the halfͲlife values range from 298 to 499 days.

Additional information on the unextracted residues would be helpful in ruling out these

residues as potential residues of concern.

Anaerobic Soil Metabolism

HalfͲlife values for halauxifenͲmethyl range from 0.94 days to 7.1 days (MRID 48557736).

Transformation products (i.e., XDEͲ729 acid, X11449757, X11406790, and CO2) observed under

anaerobic soil conditions were the same as those observed in the aerobic soil metabolism study

and are more persistent than halauxifenͲmethyl. XDEͲ729 acid and X11449757 are considered

major anaerobic soil metabolism transformation products (>10%) while the other two are

considered minor products. Across the four soils tested the maximum amount of CO2 formed

was less than 1%. An increasing large (up to 59% of the applied radioactivity) amount of

unextracted residues were observed in all studies. The extraction procedures used in the

submitted anaerobic soil metabolism study are not considered exhaustive. Additional

discussion of the unextracted residues is provided in the Aerobic Soil Metabolism section of

this document.

The halfͲlife values for XDEͲ729 acid ranged from 15 to 107 days.
34

Total halauxifenͲmethyl residues were observed to degrade with halfͲlife values ranging from

235 to 5270 days. Degradation was observed to be biphasic. When the unextracted residues

were considered as part of the total residues no appreciable transformation was observed.

Additional information on the unextracted residues would be helpful in ruling out the residues

as potential residues of concern.



Aerobic Aquatic Metabolism

HalauxifenͲmethyl transformed rapidly under aerobic aquatic conditions (MRID 48557738).

HalfͲlife values for the two different systems were calculated on a total system (water and

sediment) basis and ranged from approximately 1 day to 5 days; however, the sampling

intervals were inadequate to accurately calculate a halfͲlife for parent halauxifenͲmethyl in one

of the test systems (i.e., silt loam sediment system). Approximately 20% halauxifenͲmethyl

remained two days after treatment when the first sample was collected following application

verification at time zero.

Four transformation products were identified: XDEͲ729 acid, X11449757, X11406790, and CO2.

All transformation products were isolated at concentrations greater than 10% of the applied

radioactivity in both test systems. These transformation products were more persistent than

halauxifenͲmethyl. Across the four soils tested the maximum amount of CO2 formed ranged

from less than 1% to 16%. An increasingly large (up to 72% of the applied radioactivity) amount

of unextracted residues were observed. The extraction procedures used in the submitted study

are not considered exhaustive. Additional discussion of the unextracted residues is provided in

the Aerobic Soil Metabolism section of this document.

The halfͲlife values for XDEͲ729 acid ranged from 3 to 12 days.

Total halauxifenͲmethyl residues were observed to degradate with halfͲlife values ranging 52 to

257 days. When the unextracted residues are considered as part of the total residues one test

systems has a calculated halfͲlife value of 233 while no appreciable transformation was

observed in the other test system.

Anaerobic Aquatic Metabolism

HalauxifenͲmethyl transformed rapidly under anaerobic aquatic conditions (MRID 48557739).

HalfͲlife values for the two different systems were calculated on a total system (water and

sediment) basis and ranged from approximately 0.5 day to 5.8 days12.

Four transformation products were identified: XDEͲ729 acid, X11449757, X11406790, and CO2.

All transformation products except CO2 were isolated at concentrations greater than 10% of the

applied radioactivity in both test systems. The transformation products were more persistent

12 Data for day three are inconsistent (sandy clay loam system).
35

than halauxifenͲmethyl. Across the four soils tested the maximum amount of CO2 formed was

1%. Unextracted residues were not observed at concentrations greater than 10% applied

radioactivity in either test system.

The halfͲlife values for XDEͲ729 acid were approximately 4 days.

Total halauxifenͲmethyl residues were not observed to degrade under anaerobic aquatic

conditions. The primary transformation product observed at study termination was X11449757.

Mobility and Transport

Batch Equilibrium

Due to significant degradation of halauxifenͲmethyl in the adsorption and desorption

equilibrium experiment a sorption factor cannot be definitively determined for halauxifenͲ

methyl (MRID 48557728). The mobility (i.e., sorption factor) determined in the study may

underestimate the actual mobility of halauxifenͲmethyl due to the degradation observed.

Nevertheless, if the organic carbon partition coefficient (Koc) values estimated in the study were

used to represent halauxifenͲmethyl based on the United Nations' Food and Agriculture

Organization (FAO) Mobility classification13, halauxifenͲmethyl would be characterized as

moderately mobile in soil. Due the degradation and associated uncertainty with the estimated

Koc values for halauxifenͲmethyl, the values are not reported in this assessment but can be

obtained from the data evaluation record. The transformation products are generally more

stable and mobile than halauxifenͲmethyl.

Sorption data are available for XDEͲ729 acid and X11449757. Sorption parameters for these

compounds are presented in Table 6. Both compounds are considered to be mobile to

moderately mobile and are likely to leach under field conditions.

Table 6. Soil Mobility Data for XDEͲ729 acid and X11449757

Transformation

Product Soil Regressed Kd

(L/kg)

Regressed

Koc

KF

(L/kg) KFoc 1/n

XDEͲ729 acid

Yolo Clay loam

(1.3% OC

pH 7.1)

1.5 116 1.5 113 0.833

RefSol 01ͲA (1.1%OC,

pH 5.2)

Loamy sand

2.0 178 1.7 152 0.947

RefSol 03ͲG (2.5%OC,

pH 5.0) Loam 2.6 103 2.4 96 0.834

13 FAO. 2000. Appendix 2.Parameters of pesticides that influence processes in the soil. In FAO Information

Division Editorial Group (Ed.), Pesticide Disposal Series 8.Assessing Soil Contamination.A Reference Manual.

Rome: Food & Agriculture Organization of the United Nations (FAO). Available at

http://www.fao.org/DOCREP/003/X2570E/X2570E06.htm

37

impacting the dissipation of halauxifenͲmethyl and its environmental transformation products

under typical field conditions. For example, the temperatures reported in the field studies vary

substantially from the temperature (20 ȗC) used in the laboratory studies. The range of

reported field temperatures is provided in Table 8. Alternatively, the discrepancy in halfͲlife

values observed between the field and laboratory studies may be the results of an issue with

the laboratory studies such as inadequate extraction procedures.

Table 7. Terrestrial Field Dissipation Data for HalauxifenͲmethyl

System Name/ Characteristics Observed Total

Field DT50 (days)

Kinetic Model Fitteda

DT50 (days)

Fitting

Equation HalfͲlife Valuea



New Jersey Penn soil series, Silt loam pH

6.9 0.97 1.54 DFOP Slow t1/2=13.6

Ontario Fox soil series, Sandy loam pH 6.1 1.8 2.65 IORE TIORE=2.78

Manitoba Neuhorst soil series, Clay loam

pH 7.8 16.8 14.8 IORE TIORE=273

Saskatchewan Elstow soil series Clay pH 7.6 10.8 9.92 IORE TIORE=122

Alberta Angus Ridge and Camrose soil

series Bare plot: Loam pH 6.1 4.7 4.02 IORE TIORE=52.6

Alberta Angus Ridge and Camrose soil

series Cropped plot: Sandy clay loam pH

7.3

5.3 5.4 DFOP Slow t1/2=16

North Dakota GlyndonͲTiffany soil series

Bare plot: Sandy loam pH 6.7 9.8 9.41 DFOP Slow t1/2=250

North Dakota GlyndonͲTiffany soil series

Cropped plot: Sandy loam pH 6.5 5.1 6.46 IORE TIORE=99.4

a. The value used to estimate a model input value is the calculated SFO DT50, TIORE, or the 2nd DT50 from the DFOP

equation.The model chosen is consistent with that recommended using the, Guidance for Evaluating and Calculating

Degradation Kinetics in Environmental Media, Health Canada, U.S. Environmental Protection Agency, December 21, 2012.

The same model used to estimate the value used to derive a model input, is used to describe the DT50.

The average minimum soil temperature wasͲ5 ȗC. The biphasic transformation observed in the

halauxifenͲmethyl field studies may be a result of the seasonal change in temperature (i.e.,

more rapid degradation following application during the warmer months followed by a slow in

degradation as the temperature decreases during the winter months). Temperature adjusted

(toͲ5 ȗC) aerobic soil metabolism halfͲlife values for halauxifenͲmethyl range from 9 to 42 days.

While a temperature ofͲ5 °C seems too low to be relevant for much of the year use of the

temperature adjustment does not completely capture the enhanced persistence observed in

the field studies as compared to the laboratory studies.
38

Table 8. Field Dissipation Reported Temperatures for HalauxifenͲmethyl

System Name/ Characteristics

Air

Temperature

°C

Average

Soil Temperature

°C

2.5 cm

bgs

10 cm

bgs

50 cm

bgs

New Jersey Penn soil series

Silt loam pH 6.9

Max 40.4 34.7 32.5 28.0

Min Ͳ19.2 Ͳ3.8 Ͳ2.0 0.7

Ontario Fox soil series

Sandy loam pH 6.1

Max 33.2 39.7 43 27.6

Min 27.1 Ͳ7.1 Ͳ6.6 Ͳ2.2

Manitoba Neuhorst soil series

Clay loam pH 7.8

Max 36.1 33.2 31.3 22.8

Min Ͳ32.6 Ͳ5.3 Ͳ3.7 sm

Saskatchewan Elstow soil series Clay pH 7.6

Max 33.1 34.9 29.1 19.6

Min Ͳ37.5 Ͳ5.0 4.5 Ͳ1.8

Alberta Angus Ridge and Camrose soil series Bare

plot: Loam pH 6.1 Max 32.6 29.1 26.2 19.0

Alberta Angus Ridge and Camrose soil series

Cropped plot: Sandy clay loam

pH 7.3

Min Ͳ37.6 Ͳ6.2 Ͳ5.3 Ͳ2.5

North Dakota GlyndonͲTiffany soil series Bare

plot: Sandy loam pH 6.7 Max 34.1 36.7 31.5 23.9

North Dakota GlyndonͲTiffany soil series Cropped

plot: Sandy loam pH 6.5 Min Ͳ32.6 Ͳ11.4 Ͳ7.6 Ͳ1.5

bgs – below ground surface

smͲsensor malfunction

The only two transformation products monitored in the field dissipation studies were XDEͲ729

acid and X11449757; however, the soil extraction procedures may not have been adequate for

the transformation products as several of the spiked recovery samples were outside the

acceptable range (additional discussion of the extraction procedures provided in the Aerobic

Soil Metabolism section of this document). Both transformation products were observed to

form under field conditions. For characterization halfͲlife values for halauxifen under field

conditions are presented in Table 4 and Table 9. The observed field DT50 values for XDEͲ729

acid ranged from 11.5 day to 357 days (Table 5; halfͲlife values 11.5 to 409 days) which are

longer than observed in the aerobic soil metabolism laboratory studies (observed halfͲlife

values ranged from 3.3Ͳ19.5 and halfͲlife values range from 3.3 to 41.6 days). This suggests that

dissipation in the environment is slower than the laboratory studies indicate. Temperature

adjusted (toͲ5 ȗC) aerobic soil metabolism halfͲlife values for XDEͲ729 acid range from 26 to

333 days.
39

Table 9. Terrestrial Field Dissipation Data for XDEͲ729 acid

System Name/ Characteristics Observed

Total Field

DT50 (days)

Kinetic Model

Fitteda



DT50 (days)

Fitting Equation

HalfͲlife Valuea



New Jersey Penn soil series

Silt loam pH 6.9

14.4

12.4

SFO

t1/2=12.4

Ontario Fox soil series

Sandy loam pH 6.1

11.5

11.5

SFO

t1/2=11.5

Manitoba Neuhorst soil series

Clay loam pH 7.8

255

184

SFO

t1/2=184

Saskatchewan Elstow soil series Clay pH 7.6 316

361

SFO

t1/2=361

Alberta Angus Ridge and Camrose soil series

Bare plot: Loam pH 6.1 23

21.1

IORE

TIORE=301

Alberta Angus Ridge and Camrose soil series

Cropped plot: Sandy clay loam

pH 7.3

17.4

17.2

DFOP

Slow t1/2=244

North Dakota GlyndonͲTiffany soil series

Bare plot: Sandy loam pH 6.7 357

409

SFO

t1/2=409

North Dakota GlyndonͲTiffany soil series

Cropped plot: Sandy loam pH 6.5 291

214

SFO

t1/2=214

a. The value used to estimate a model input value is the calculated SFO DT50, TIORE, or the 2nd DT50 from

the DFOP equation.The model chosen is consistent with that recommended using the, Guidance for

Evaluating and Calculating Degradation Kinetics in Environmental Media, Health Canada, U.S.

Environmental Protection Agency, December 21, 2012. The same model used to estimate the value

used to derive a model input, is used to describe the DT50.

At several of the sites halauxifenͲmethyl was observed throughout the soil profile [(New Jersey:

0Ͳ15 cm, 15Ͳ30 cm, 30Ͳ45 cm, 45Ͳ60 cm, 60Ͳ75 cm, and 75Ͳ90 cm); (Manitoba: 0Ͳ15 cm, 15Ͳ30

cm and 30Ͳ45 cm); (Saskatchewan: 0Ͳ15 cm, 15Ͳ30 cm); (Alberta: 0Ͳ15 cm and 15Ͳ30 cm; 30Ͳ45

cm) (North Dakota: 0Ͳ15 cm and 15Ͳ30 cm)] the day after application for at least one replicate

sample. For the New Jersey site, two replicates had detections down to 45 cm while only one

replicate had detections at depths greater than 45 cm. Since there was no rain or irrigation

reported on the day of application or the day after application, the mechanism of residue

transport though the soil profile is unclear and likely not be the result of traditional leaching.

HalauxifenͲmethyl and/or its transformation products (XDEͲ729 acid or X11449757) were also

observed to move down through the soil profile overtime suggesting that classic leaching as

well as transformation occurs through the soil profile under field conditions.

A storage stability study is ongoing, with interim results showing stability of XDEͲ729 methyl,

XDEͲ729 acid, and X11449757 in frozen soil for up to 12 months (MRID 49065801). The

maximum storage interval used in the interim stability results did not exceed the maximum

storage interval used for the test soil samples of 752 days.
40

Environmental chemistry methods along with an independent laboratory validation study

report the limits of detection (LOD) and quantification (LOQ) of halauxifenͲmethyl, XDEͲ729

acid, and X11449757 in soil [0.02 μg/kgand 0.05 μg/kg (MRIDs 48557862 and 48557785)] and

water [0.05 μg/L (MRID 48557787 and 48557788)].

A more sensitive environmental chemistry method (MRID 49702101) reports a LOD of 0.00045

μg/kg and a LOQ of 0.0015 μg/kg in soil for halauxifenͲmethyl and XDEͲ729. There is no

independent laboratory validation for this method, therefore, the study has not been reviewed.

An environmental chemistry method for halauxifenͲmethyl and XDEͲ729 acid in compost (MRID

4967103; LOD = 0.02 μg/kg; LOQ = 0.05 μg/kg) is available; however, no independent

laboratory validation (ILV) has been submitted to support this method. Since an ILV has not

been received the method has not been reviewed; however, this method does not appear to be

the same as that submitted and reviewed soil method (MRIDs 48557862 and 48557785).

Compost

A nonͲguideline study (Fate of XDEͲ729 Methyl Ester Applied to Cereal Crops: Effects of Straw

Residues on Legume and Vegetable Crops; MRID 48901102) was submitted that looked at the

use of wheat treated with halauxifenͲmethyl as a “compost” material to grow tomato, lettuce,

lentils, alfalfa, soybean, and broad bean [seeding emergence (formulation study): tomato IC25 =

0.00023 lb a.e./A; soybean IC25 = 0.00593 lb a.e./A; broad bean IC25 = 0.00187 lb a.e./A]. This

study suggests that when wheat is treated with halauxifenͲmethyl the residues in the foliage

are below the limit of detection (LOD; not reported in the submitted study) at harvest and;

therefore, are not a compost concern. However, the halauxifenͲmethyl application rate was not

provided in the report nor was the LOD provided for halauxifenͲmethyl and its environmental

transformation products in wheat (or straw). Since halauxifenͲmethyl residues were not

determined in the wheat (or straw) used in this “compost” study, the impact that composting

has on halauxifenͲmethyl residues on compost materials which retain halauxifenͲmethyl

residues cannot be determined.

A nonͲguideline study (HalauxifenͲMethyl and HalauxifenͲAcid Degradation in Manure/Straw

Compost; MRID 49637101) was submitted that examined the rate of transformation of

halauxifenͲmethyl, XDEͲ729 acid following direct introduction to a compost system (e.g., via

animal excrement). Reported halfͲlife values for halauxifenͲmethyl and XDEͲ729 acid

independently were approximately 3 days. This study is classified as upgradable to

supplemental if the following data were made available for evaluation: storage and shipping

conditions, storage and shipping control spikes, and an ILV for the methods used in this study.

Due to the absence of these data, the interpretation of the study is limited as it is possible that

halauxifenͲmethyl and XDEͲ729 acid may have degraded during storage or shipping. Therefore,

in absence of these data there is no confidence in the reported halfͲlife values being

representative of halauxifenͲmethyl or XDEͲ729 acid in compost. In addition, the representation

of the composting conditions utilized in this study are not discussed nor was a mass balance

provided.
41

A nonͲguideline study (Bioassay Study of Composted HalauxifenͲmethyl Treated Wheat Straw;

MRID 49637102) was submitted that examined plant growth after four different crop species

(clover, soybean, sunflower, and wheat) were planted into compostͲpeat mixtures. The

compost was derived from spring wheat that had been treated with GFͲ2686 at four times the

proposed application rate. Replicate plants were evaluated for herbicide injury symptoms (i.e.,

visual signs of toxicity), as well as plant height and weight. Reduction in plant height and weight

were observed in the sunflower trial.Nevertheless, a direct link between the observed effects

and halauxifenͲmethyl and XDEͲ729 cannot be made because GFͲ2686 is a coͲformulated

product that includes florasulam. In addition, according to the study authors the salinity levels

were elevated. The authors concluded that the elevated salinity may have contributed, at least

in part, to the observed effects. Although salinity levels were high, the greatest effects were not

observed in those samples with the highest salinity. Therefore, this study does not rule out, nor

does it establish a direct link for halauxifenͲmethyl and XDEͲ729 in compost as an exposure

route of concern. An ILV for the methods used in this study were not provided; thus, the study

is classified as upgradable to supplemental if ILV were to be made available for evaluation.

In another nonͲguideline study (Bioassay Study of Composted HalauxifenͲmethyl Treated Wheat

StrawͲPart 2 Bioassay Study of HalauxifenͲmethyl Treated Compost Applied as Mulch to

Commercial Seedlings; MRID 49702102) three different seedlings (sunflower, tomato, and

marigold) were transplanted into peat and top dressed with a compost mixture that was spiked

with halauxifenͲmethyl and XDEͲ729 acid. Replicate plants were evaluated for herbicide injury

symptoms. Effects were observed for all three species and are consistent with auxin herbicide

effects. The concentration of halauxifenͲmethyl and XDEͲ729 acid in the compost mixture is

unclear but it suggests that if halauxifenͲmethyl and/or XDEͲ729 are present in compost

materials, effects to nonͲtarget plants are possible. This study is also classified as upgradable to

supplemental if an ILV for the analytical methods utilized in this study were to become available

for evaluation.

Residue Carryover

In efficacy trials, not submitted to the Agency for review but summarized by the applicant,

canola, corn, barley, flax, mustard, oats, peas, soybeans, sunflower, lentils and wheat were

planted into plots previously treated with halauxifenͲmethyl at application rates 1x to 8x the

proposed label rate. Injury to lentils was observed when planted 10Ͳ11 months after

application; however, no injury was reported when lentils were replanted after 22 months. Soil

concentrations were not reported and toxicity data are not available for lentils; therefore, the

results of the summarized study cannot be compared to available toxicity data and suggests

that under some environmental conditions halauxifenͲmethyl residues (parent or

environmental transformation products) may persist in the soil at concentrations high enough

to cause crop damage to sensitive crops (and other nonͲtarget plants). This is consistent with

the terrestrial field study results that suggest halauxifenͲmethyl and its environmental

transformation products are more persistent in the environment than the laboratory studies

suggest.
42

Bioconcentration

Based on a fish bioconcentration study, halauxifenͲmethyl and the corresponding

environmental transformation products are not expected to bioaccumulate to levels of concern

(whole fish BCFs ranged from 183Ͳ233). HalauxifenͲmethyl residues depurated rapidly.

B. Receptors

Aquatic and Terrestrial Effects

Table 10 gives examples of taxonomic groups and species tested to help understand potential

ecological effects of pesticides to nonͲtarget organisms. Within each of these very broad

taxonomic groups, a measure of effect from exposure is selected from the available test data.

Table 10. Taxonomic Groups and Test Species Generally Used Evaluated for Ecological Effects

in ScreeningͲLevel Risk Assessments

Taxonomic Group Example(s) of Representative Species

Birds1 Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)

Zebra Finch (Taeniopygia guttata)

Mammals Laboratory rat (Rattus norvegicus)

Terrestrial invertebrates Honey bee (Apis mellifera L.)

Freshwater fish2  Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Freshwater invertebrates Water flea (Daphnia magna)

Estuarine/marine fish Sheepshead minnow (Cyprinodon variegatus)

Estuarine/marine invertebrates Mysid (Americamysis bahia)

Eastern oyster (Crassostrea virginica)

Terrestrial plants3 Monocots – corn (Zea mays)

Dicots – soybean (Glycine max)

Aquatic plants and algae Duckweed (Lemna gibba)

Green algae (Pseudokirchneriella subcapitata) 1 Birds represent surrogates for amphibians (terrestrial phase) and reptiles. 2 Freshwater fish may be surrogates for amphibians (aquatic phase). 3 Four species of two families of monocots, of which one is corn; six species of at least four dicot families, of which

one is soybeans.

Ecosystems Potentially at Risk

The ecosystems potentially at risk include the areas adjacent to the application sites and water

bodies adjacent to the application sites and downstream. In addition, organisms that inhabit

the application site (e.g., birds foraging for insects within application areas) are also considered

to be part of the ecosystems at risk.
43

C. Assessment Endpoints

FIFRA Part 158 guideline toxicity tests (CFR 40 §158.630, 2009) are intended to determine

pesticidal effects on a variety of organisms, including birds, mammals, fish, terrestrial and

aquatic invertebrates, and plants. These tests include both shortͲterm and longͲterm exposure

periods and evaluate the survival, reproduction, and/or growth of laboratory species. The

studies, when available, are used to evaluate the potential of a pesticide to cause adverse

effects, to determine whether further testing is required, and to determine the need for

precautionary label statements to minimize the potential adverse effects to nonͲtarget animals

and plants (CFR 40 §158.630, 2009).

Assessment endpoints are intended to represent valued attributes of the environment that, if

detrimentally altered, could pose a risk to the environment. The assessment endpoints of this

ecological risk assessment include terrestrial and aquatic animal and plant mortality following

acute exposure to halauxifenͲmethyl and some of the transformation products and terrestrial

and aquatic animal reproduction, growth and survival effects from chronic exposure to

halauxifenͲmethyl and some of its transformation products. Surrogate species are used to

represent all freshwater fish (2000+) and bird (680+) species in the United States. For

mammals, acute studies are usually limited to the Norway rat (Rattus norvegicus). Usually data

from estuarine/ marine testing are limited to a crustacean, a mollusk, and a fish. The

assessment of risk or hazard makes the assumption that avian toxicity is similar to terrestrialͲ

phase amphibians and reptiles, unless more appropriate data are available. The same

assumption is made for fish and aquaticͲphase amphibians. The most sensitive toxicity

endpoints are used from surrogate test species to estimate treatmentͲrelated direct effects on

mortality and reproductive and growth assessment endpoints.

For terrestrial and semiͲaquatic plants, the screening assessment endpoints for nonͲtarget

species (crops and nonͲcrop plant species) are based on the emergence and growth of seedlings

and vegetative vigor of annuals. Measures of effect for this assessment focus on impacts on

plant emergence and/or on active growth.

For aquatic plants, the assessment endpoint is the maintenance and growth of standing crop or

biomass. Measures of effect for this assessment focus on nonvascular, e.g., algae, and vascular

plants, e.g., duckweed (Lemna gibba), growth rates and biomass measurements.

D. Conceptual Model

The conceptual model used to depict the potential ecological risk associated with halauxifenͲ

methyl is fairly generic and assumes that as an herbicide, halauxifenͲmethyl is capable of

affecting terrestrial and aquatic organisms (animals and plants) provided environmental

exposure is high enough as a result of proposed label uses to cause adverse effects. Therefore,

this assessment considers potential exposure as a result of direct applications, spray drift,

leaching and runoff.
44

Risk Hypothesis

For this assessment, the risk to nonͲtarget organisms is based on potential effects from the

application of halauxifenͲmethyl to the environment. The Agency presumes the following risk

hypothesis for this screening level assessment:

Based on mode of action, the proposed use patterns, and the sensitivity of nonͲtarget

aquatic and terrestrial species, the proposed uses of halauxifenͲmethyl have the

potential to reduce survival, reproduction, and/or growth in terrestrial and aquatic

animals and plants through direct application, spray drift and/or runoff.

In order for a chemical to pose an ecological risk, it must reach nonͲtarget organisms at

concentrations found to cause adverse effects. The assessment of ecological exposure

pathways in this assessment includes an examination of the source and potential migration

pathways to halauxifenͲmethyl exposure, and the determination of potential adverse effects on

nonͲtarget species.

Diagram

Application methods for halauxifenͲmethyl involve foliar spray applications via aerial or ground

equipment. Ecological receptors that may potentially be exposed to halauxifenͲmethyl include

terrestrial and semiͲaquatic wildlife (i.e., mammals, birds, amphibians, terrestrial invertebrates,

and reptiles) and plants. In addition, aquatic receptors (e.g., freshwater and estuarine/marine

fish and invertebrates, amphibians, and plants) may also be exposed as a result of potential

movement of halauxifenͲmethyl via spray drift and/or runoff from the site of application to

aquatic environments. The assessment following the process depicted in Figure 2 (aquatic

exposure) and Figure 3 (terrestrial exposure) forms the basis for identifying potential

endpoints, stressors, and ecological effects associated with halauxifenͲmethyl use.

Since volatility of halauxifenͲmethyl does not appear to be an issue, this assessment does not

take into account atmospheric transport of vapor phase halauxifenͲmethyl or the

corresponding transformation products in estimating environmental concentrations. Exposure

to terrestrial animals is based on dietary consumption of foliar residues while aquatic

assessments assume that all major potential routes of direct exposure are accounted for.
Figure 2. Conceptual Model Depicting Stressors, Exposure Pathways, and Potential Effects to Aquatic Organisms from the

Proposed Uses of HalauxifenͲmethyla

a. Dotted lines indicate exposure pathways that are hypothesized to have a low likelihood of contributing to ecological risk Bold

lines indicate route of exposure considered of higher importance for halauxifenͲmethyl

Stressor 

SourceReceptors 

AttributeChange

Halauxifen-methyl applied to wheat, barley or triticale 

Direct 

application Spray drift 

Birds / Terrestrialphase amphibians / reptiles / mammals

Terrestrial 

insects 

Individual organisms Reduced survival Reduced growth Reduced reproduction 

Food chain Reduction in prey 

Habitat integrity Reduction in primary productivityReduced cover Community change 

Terrestrial/riparian plants 

grasses/forbs, fruit, seeds 

(trees, shrubs) 

Runoff 

Mammals

ExposureMedia

Soil

Ingestion

Ingestion

Ingestion

Ingestion

Dermal uptake/Ingestion 

Long range 

atmospheric 

transport 

Root uptake 

Wet/dry deposition 

Birds / 

Amphibians 

Ingestion

Ground water 
Figure 3. Conceptual Model Depicting Stressors, Exposure Pathways, and Potential Effects to Terrestrial Organisms from the

Proposed Uses of HalauxifenͲmethyla

a. Dotted lines indicate exposure pathways that are hypothesized to have a low likelihood of contributing to ecological risk Bold

lines indicate route of exposure considered of higher importance for halauxifenͲmethyl

Stressor 

SourceReceptors 

AttributeChange

Halauxifen-methyl applied to wheat, barley or triticale 

Spray drift 

Fish/aquatic-phase amphibiansEggs LarvaeJuveniles / Adults 

Individual organisms Reduced survival Reduced growth Reduced reproduction 

Food chain Reduction in algae Reduction in prey 

Habitat integrity Reduction in primary productivityReduced cover Community change 

Surface water/ 

Sediment 

Runoff 

Aquatic Animals Invertebrates Vertebrates 

ExposureMedia

Uptake/gills or integument 

Ingestion Ingestion

Long-range

atmospheric 

transport 

Wet/dry deposition 

Soil Ground water 

Uptake/gills or integument 

Aquatic Plants Non-vascular

Vascular 

Uptake/cell,

roots, leaves Riparian plant terrestrial 

exposure
E. Analysis Plan

This document characterizes the environmental fate of halauxifenͲmethyl to assess whether

proposed label uses of halauxifenͲmethyl on barley, triticale, and wheat provide a means of

exposure to nonͲtarget species. Additionally, the toxicity of halauxifenͲmethyl and its

environmental transformation products are characterized, and then both potential exposure

and effects are integrated to estimate potential risk to nonͲtarget animals and plants.

The maximum proposed label application rates and minimum retreatment intervals for use of

halauxifenͲmethyl on barley, triticale, and wheat were selected for modeling environmental

concentrations for this screeningͲlevel deterministic (riskͲquotient based) assessment. The

most sensitive toxicity endpoints from surrogate test species are used to estimate treatmentͲ

related effects on survival, growth and reproduction.

Measures to Evaluate Risk Hypotheses and Conceptual Model

Measures of Exposure

Measures of exposure are based on aquatic and terrestrial models that estimate environmental

concentrations of halauxifenͲmethyl using maximum proposed labeled application rates and

application methods (see Section III.A.4) that have the greatest potential for offͲsite transport

of the chemical.

Aquatic Modeling

Surface water ECCs for halauxifenͲmethy, halauxifen (XDEͲ729 acid), and total halauxifenͲ

methyl residues resulting from the proposed use of halauxifenͲmethyl were calculated using

the Surface Water Concentration Calculator (SWCC Version 1.106). The measure of exposure

used to assess risk to aquatic species is the 1ͲinͲ10 year return peak or rolling mean

concentration. The 1ͲinͲ10 year peak is used for estimating acute exposures to aquatic

organisms. The 1ͲinͲ10Ͳyear 60Ͳday mean concentration is used for assessing chronic exposure

to fish. The 1ͲinͲ10 year 21Ͳday mean concentration is used for assessing chronic exposures to

aquatic invertebrates.

Terrestrial Modeling

The model used to produce terrestrial EECs on food items is TͲREX. The model used to derive

EECs relevant to terrestrial and wetland plants is TerrPlant. These models are parameterized

using relevant reviewed applicantͲsubmitted data. The AgDRIFT spray drift model (v2.1.1;

August 2010) is used to assess exposures of organisms to halauxifenͲmethyl residues deposited

on terrestrial habitats by spray drift directly following application.
48

F. Measures of Effect

The acute measures of effect routinely used in screening level assessments are the LD50, LC50 or

IC50, depending on taxa (see Table 11). Endpoints for chronic measures of effect are the NOAEL

or NOAEC.

Table 11. Acute and Chronic Measures of Effect

TAXA ASSESSMENT MEASURE OF EFFECT

Aquatic Animals (Freshwater fish

and inverts. and estuarine/marine

fish and inverts.)

Acute Lowest tested EC50 or LC50 (acute toxicity tests)

Chronic Lowest NOAEC (early lifeͲstage or full lifeͲcycle tests)

Terrestrial Animals

Birds

Acute/SubͲacute Lowest LD50 (single oral dose) and LC50 (subacute dietary)

Chronic Lowest NOAEC (21Ͳweek reproduction test)

Terrestrial Animals

Mammals

Acute Lowest LD50 (single oral dose test)

Chronic Lowest NOAEC (twoͲgeneration reproduction test)

Plants

Terrestrial nonͲlisted (monocots

and dicots)

Acute/Chronic Lowest IC25 (seedling emergence and vegetative vigor)

Plants

Terrestrial listed (monocots and

dicots)

Acute/Chronic IC05 or NOAEC associated with the lowest IC25 (seedling

emergence and vegetative vigor)

Plants

Aquatic nonͲlisted (vascular and

nonͲvascular)

Acute/Chronic Lowest IC50

Plants

Aquatic listed (vascular and algae)

Acute/Chronic IC05 or NOAEC associated with the lowest IC50

III. ANALYSIS

A. Use Characterization

HalauxifenͲmethyl may be applied as a foliar spray twice per year via aerial or ground

equipment at a maximum single application rate of 0.0091 lb active ingredient (a.i.)/acre or

0.0086 acid equivalents (a.e.)/acre and a maximum of 0.0182 lb a.i./A/year (0.0172

a.e./acre/year) according to the proposed labels (Table 2).

Barley, triticale, and wheat are grown across the country and based on National Agricultural

Statistics Service (NASS) data (from 2003 and 2013) approximately 3,780,000 and 3,301,000

acres of barley planted and harvested, respectively, each year (Table 12) while approximately

49,448,000 and 58,089,000 acres of wheat are planted and harvested each year, respectively,
49

according to the same source. No data are available for triticale. The spatial distribution of

wheat grown in the United States is provided in Figure 4.

Table 12. National Harvest and Planted Statistics for Proposed HalauxifenͲmethyl Use Sites

Crop

Year

2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003

1,000 acres

BarleyͲ

Harvested 3,000 3,244 2,239 2,465 3,113 3,779 3,502 2,951 3,269 4,021 4,727

BarleyͲ

Planted 3,480 3,637 2,559 2,872 3,567 4,246 4,018 3,452 3,875 4,527 5,348

WheatͲ

Harvested 45,157 48,921 45,705 47,619 49,893 55,699 50,999 46,800 50,104 49,969 53,063

WheatͲ

Planted 56,156 55,666 54,409 53,593 59,168 63,193 60,460 57,334 57,214 59,644 62,141

National Agricultural Statistics Service (NASS) data accessed 1/2/2014


50

Figure 4. Wheat Growing Areas in the United States

B. Exposure Characterization

Environmental Fate and Transport Characterization

HalauxifenͲmethyl may reach surface waters through spray drift and penetration of the canopy

during application and foliar washoff to the soil followed by runoff of halauxifenͲmethyl sorbed

soil or dissolved phase halauxifenͲmethyl. HalauxifenͲmethyl may also leach to groundwater.

Field dissipation studies show that halauxifenͲmethyl transforms in the environment—this

reduces the likelihood that halauxifenͲmethyl will contaminate surface water or groundwater.

However, because the degradation of halauxifenͲmethyl is to mobile or highly mobile

compounds, it is possible that such transformation products may contaminate surface water, as

well as leach to groundwater.

Measures of Aquatic Exposure

Aquatic Exposure Modeling

The environmental fate properties and crop management practices used for modeling for

halauxifenͲmethyl, halauxifen, and total residues (TR; as well as TR plus unextracted residues

are also provided) are summarized in Table 13.

Environmental fate data parameters used in the modeling were selected from the submitted

studies in general accordance with Guidance for Selecting Input Parameters in Modeling the

Environmental Fate and Transport of Pesticides (Version 2.1, October 22, 2009) and the draft
51

Guidance for Modeling Pesticides Total Toxic Residues (TTR) May 20, 2009. Detailed

description, documentation, and direct links for running models used for estimating aquatic

environmental concentrations can be found on EPA’s water models website14.

Table 13. Input Parameters Used for Modeling HalauxifenͲmethyl Residues

Parameter (units)

Input Value Data

Source HalauxifenͲ Comments

methyl

Halauxifen

(XDEͲ729) TTRa

Henry’s Law

Constant 20 °C 

atm m3

/mol

1.2 x 10Ͳ11 1.2 x 10Ͳ11 1.2 x 10Ͳ11 MRID

48557869 Value only available for halauxifenͲmethyl.

Vapor Pressure

(25 °C) torr

1.1 x 10Ͳ10 1.8 x 10Ͳ9 1.8 x 10Ͳ9

MRIDs

48557727

(methyl)

48557726

(acid)

Data available for both halauxifenͲmethyl

and halauxifen.

Water Solubility

(20 °C) 1.8 3100 3100

MRIDs

48557723

(methyl) and

48557721

(acid)

Data available for both halauxifenͲmethyl

and halauxifen.

Molecular Weight

g/mol 345.16 331.13 345.16 Calculated Used ChemDraw Ultra to calculatemolecular weight.

Application Rate lb

a.i./A (kg/ha)

0.0091

(0.01)

0.0086

(0.01)

0.0091

(0.01)

Proposed

label

This is the highest maximum single

application rate permitted on the proposed

halauxifenͲmethyl labels.

Application Method

(CAM) 2 2 2 EFEDGuidance Foliar application.

Application Efficiency 0.95 0.95 0.95 EFED

Guidance

Aerial application permitted on proposed

label.

Spray Drift Fraction 0.125 0.125 0.125 EFED

Guidance

White. K., Khan, F., Peck, C., Corbin, M.,

Guidance on Modeling Offsite Deposition of

Pesticides via Spray Drift for Ecological and

Drinking Water Assessments, December 19,

2013

Scenario (weather) NDwheatSTD

(w14914) Proposed Use Sites

Applications Number 2 2 2

Proposed

label

Two seasons are assumed per year

beginning April 1 (springͲsummer) and

October 1 (fallͲwinter). Since the maximum

single application rate is equal to the

maximum seasonal application rate, two

applications are assumed to occur on April 1

and Oct 1.

Application Interval 183 183 183

Application Date April 1

and Oct. 1

April 1

and Oct. 1

April 1

and Oct. 1

Koc mL/goc 88 88 88

MRID

48557728

Supplemental

Due to degradation of halauxifenͲmethyl in

the batch equilibrium studies the value for

halauxifen (XDEͲ729 acid) was used for

halauxifenͲmethyl. Regressed Koc values

14 http://www2.epa.gov/exposureͲassessmentͲmodels
52

were used to develop model input value.

Since barley, wheat, and triticale are not

typically grown on muck soils the sorption

data from the muck soil was not

considered.

Hydrolysis HalfͲlife

(days) at 25ȗC 155 0 0

MRID

48557729

Acceptable

Aerobic Soil

Metabolism HalfͲlife

(days) 38b, c (Ͳ5°C) 298d,e (Ͳ5°C)

254f (Ͳ5°C)

3511g (Ͳ5°C)

MRID

48557735

Supplemental

See Footnote h.

The aerobic soil metabolism studies were

conducted at 20 °C [corresponding halfͲlife

at 25 °C is 3.4 (methyl), 26 (acid), 22.5 (TR),

and 310 (TR + UE) days]; however, based on

the field dissipation studies under typical

field conditions the soil temperature may

be a lot lower. Surface water simulations

were conducted (cited halfͲlife was

referenced to 25 °C since SWCC assumes a

reference temperature of 25 °C) to

represent a metabolism halfͲlife under

cooler soil conditions [i.e., the average

minimum value (Ͳ5°C) reported for the

terrestrial field studies. Note: PRZM (in

SWCC) does not simulate temperature in

the soil; however, PRZM in PRZMͲGW does.

While a temperature ofͲ5 °C seems too low

to be relevant for much of the year, the

temperature adjustment does not account

for the increased persistence observed in

the field studies.

Aerobic Aquatic

Metabolism HalfͲlife

days

10.3 (20°C) 23.8 (20°C) 490 (20°C)

0 (25°C)

MRID

48557738

Supplemental

The corresponding halfͲlife values at 25 °C

are: 7.3 (methyl), 16.8 (acid), and 347 (total)

days

Anaerobic Aquatic

Metabolism HalfͲlife

days

6.7 (20°C) 5.4 (20°C) 0

MRID

48557739

Supplemental

The corresponding halfͲlife values at 25 °C

are 4.7 (methyl) and 3.8 (acid) days.

Aqueous Photolysis

(days) 0.003 0.02 38.4

MRID

48557731

Supplemental

Value for total halauxifenͲmethyl residues

calculated by subtracting out the amount of

CO2 formed throughout the study.

a. Total residues (TR) includes halauxifenͲmethyl, halauxifen, X11449757, X11406790, and degradates 1, 2, 4, 10, 11, and 14.

b. The 90th percentile confidence bound on the mean halfͲlife value is 4.7 based on the aerobic soil metabolism studies

conducted at 20 °C.

c. If the halfͲlife values from the terrestrial dissipation study were used to calculate the model input value a value of 167

days would be used.

d. The 90th percentile confidence bound on the mean halfͲlife valueis 37.3 based on the aerobic soil metabolism studies

conducted at 20 °C; a higher halfͲlife value was calculated for the acid than the total residues due of the variability in the

halfͲlife values (i.e., larger standard deviation) used in the 90th percentile confidence bound calculation

e. If the halfͲlife values from the terrestrial dissipation study were used to calculate the model input value a value of 301

days would be used.

f. The 90th percentile confidence bound on the mean halfͲlife value is 32 based on the aerobic soil metabolism studies

conducted at 20 °C.
53

g. The 90th percentile confidence bound on the mean halfͲlife value is 439 based on the aerobic soil metabolism studies

conducted at 20 °C

h. Because the unextracted residues cannot be ruled out as a residue of toxicological concern the amount of unextracted

residues was added to the concentrations of halauxifenͲmethyl, XDEͲ729 acid, X11449757, X11406790 at each sampling

Input values provided in italic font are for TTR plus unextracted residues (or TTR+EU).

EECs are reported in Table 14. The TR EECs shown in italics take into account the unextracted

residues observed in the soil studies and are likely conservative concentrations. If the

unextracted residues are truly nonͲextractable or not bioavailable residues the values excluding

unextracted residues should be considered. The TR plus unextracted residue EECs; however,

also likely capture the difference in persistence noted between the laboratory and field data. If

additional data become available on the adequacy of the extraction procedures or the

identification of the nonͲextracted residues, EECs with less uncertainty can be modeled.

However, the EECs are expected to fall within the range of EECs report in Table 14.

Table 14. Estimated Environmental Concentrations Based on the Proposed Use of HalauxifenͲ

methyl

Residue

Surface Watera Groundwaterb

1ͲinͲ10 Year

Peak

Post

Breakthrough

Average Peak 4 Day

Average

21 Day

Average

60 Day

Average

μg/L

HalauxifenͲmethylc 0.15 0.14 0.11 0.04 <0.05f <0.05f

Halauxifen (XDEͲ729

acid)d 0.19 0.19 0.15 0.06 0.76 0.65

Total HalauxifenͲ

methyl Residuese

1.0

4.1

1.0

4.1

1.0

4.1

1.0

4.1

0.62

4.9

0.51

4.5

a. SWCC Version 1.106, ND Wheat PRZM Standard Scenario

b. PRZMͲGW Version 1.07

c. Results are in terms of active ingredient and assumes 100% of the material applied is the methyl

ester; simulations were done that did not include the temperature adjustment and the estimated

concentrations are similar (only slightly lower) than the EECs presented.

d. Results are in terms of acid equivalentsand assumes 100% of the material applied is the acid

e. Residues included in surface water modeling are halauxifenͲmethyl, XDEͲ729 acid, X11406790

X11449757 and degradates 1, 2, 4, 10, 11, and 14; residues included in groundwater modeling are

halauxifenͲmethyl, XDEͲ729 acid, X11406790 andX11449757.

f. Estimated concentration is less than the limit of detection (LOD) in water.

Values in italic considered the unextracted residues as a residue of concern.

PRZMͲGW was used to calculate estimated concentrations in groundwater. The PRZMͲGW

conceptual model represents vulnerable wells that may be used for irrigation water. The PRZMͲ

GW estimated concentrations are also provided in Table 14.
54

Measures of Terrestrial Exposure

Spray Drift Exposure

Spray deposition curves calculated using AgDRIFT (Version 2.1.1) were used to estimate the

distance from the edge of the field to where effects to nonͲtarget organisms are no longer of

concern. The proposed halauxifenͲmethyl labels provide vague spray drift language. Ground

applications are to produce largeͲdroplet spray droplets; however, the diameter size (Dv0.5) is

not provided nor is a reference in terms of ASAE droplet spectrum (e.g., coarse to very coarse)

provided. Wind speed restrictions are also not provided for ground applications. Aerial

applications are not permitted at wind speeds greater than 15 mph. No reference to a spray

drift droplet size is provided for aerial applications. Tier 1 estimated point concentrations are

provided at various distances off field for both aerial (Table 15) and ground (Table 16)

applications.

Terrestrial Exposure Modeling

The application method for the proposed halauxifenͲmethyl use on barely, triticale, and wheat

are limited to foliar spray via aerial or ground equipment. Therefore, for this terrestrial

exposure assessment, only foliar applications are considered. The EECs used for terrestrial

animal exposure are derived from the Kenaga nomograph, as modified by Fletcher et al. (1994),

based on a large set of actual field residue data. The upper limit values from the nomograph

represent the 95th percentile of residue values from actual field measurements (Hoerger and

Kenaga, 1972). The Fletcher et al. (1994) modifications to the Kenaga nomograph are based on

measured field residues from 249 published research papers, including information on 118

species of plants, 121 pesticides, and 17 chemical classes. These modifications represent the

95th percentile of the expanded data set. Risk quotients (RQs) are based on the most sensitive

LD50, LC50 and NOAEC for birds (passerine, bobwhite quail or mallard duck) and for mammals

(based on lab rat studies).

Terrestrial estimated environmental concentrations (Table 17) for halauxifenͲmethyl were

derived using the maximum proposed single application rates (for plants) and maximum annual

application rate (animals). Terrestrial exposure estimates for avian and mammalian risk

assessments were derived using the TͲREX model (version 1.5.2, March 22, 2012). The default

35Ͳday foliar halfͲlife value was used for modeling EECs on terrestrial food items. Because a

default 35Ͳday foliar halfͲlife is used in the terrestrial modeling, the terrestrial EECs are

expected to account for both the parent and the free acid. A complete description of the input

parameters and output is contained in APPENDIX E.
55

Table 15. Tier I Spray Drift Analysis: Offsite Concentrations (in lb a.i./acre) at Various Distances Downwind From a Field Treated

with HalauxifenͲmethyl Using Aerial Equipment

Application

Rate

(lb a.i./a)

Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

10 25 50 75 100 150 200 250 300

0.0091

VF2F Air 0.0039 0.0033 0.0027 0.0024 0.002 0.0016 0.0013 0.0011 0.0009

F2M Air 0.003 0.002 0.0016 0.0011 0.0009 0.0006 0.0004 0.0003 0.0003

M2C Air 0.0027 0.0015 0.001 0.0007 0.0005 0.0003 0.0002 0.0002 0.0001

C2VC Air 0.0025 0.0013 0.0007 0.0005 0.0003 0.0002 0.0001 9.95EͲ05 7.99EͲ05

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM, Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse

to Very Coarse (C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A

Table 16. Tier I Spray Drift Analysis: Offsite Concentrations (in lb a.i./acre) at Various Distances Downwind From a Field Treated

with HalauxifenͲmethyl Using Ground Equipment

Application

Rate

(lb a.i./a)

Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

10 25 50 75 100 150 200 250 300

0.0091

VF2F

Ground

High Boom 0.0024 0.0009 0.0005 0.0003 0.0002 0.0001 0.0001 8.49EͲ05 6.85EͲ05

Ground Low

Boom 0.0008 0.0003 0.0002 0.0001 8.63EͲ05 6.03EͲ05 4.65EͲ05 3.78EͲ05 3.18EͲ05

F2M/C

Ground

High Boom 0.0004 0.0002 0.0001 7.94EͲ05 6.35EͲ05 4.60EͲ05 3.62EͲ05 2.98EͲ05 2.53EͲ05

Ground Low

Boom 0.0003 0.0001 6.70EͲ05 4.98EͲ05 4.04EͲ05 2.99EͲ05 2.40EͲ05 2.01EͲ05 1.73EͲ05

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM, Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground high boom based on 90th percentile

Application rate 0.0091 lb a.i./A
56

Table 17. Estimate Concentrations on Potential Food Items Following LabelͲSpecified

Applications of HalauxifenͲmethyl Using the TͲREX Model

USE DIETARYͲBASED EECs KENAGA VALUES

Upper Bound (ppm)

Wheat, Barley and Triticalea

Short Grass 3.98

Tall Grass 1.82

Broadleaf Plants 2.24

Fruits/Pods/Seeds 0.25

Arthropods 1.56 a Inputs:2 applications at 0.0091 lb a.i./acre with a 10Ͳday application interval.

Exposure to upland and wetland plants is estimated using the TerrPlant (version 1.2.2, October

29, 2009) screening model. TerrPlant estimates potential exposure from a single application

using default assumptions for runoff and spray drift. For runoff plus drift, TerrPlant

incorporates two similar conceptual models for depicting dry and semiͲaquatic (wetland) areas

of terrestrial habitats. For both scenarios, a nonͲtarget area is adjacent to the treated field.

Pesticide exposures to plants adjacent to the treated field are estimated to receive runoff and

drift from the treated field.For a dry area adjacent to the treated field, runoff exposure is

estimated as sheet runoff.In the model, sheet runoff is defined as the amount of pesticide in

water that runs off of the soil surface of a treated field which is equal in size to the nonͲtarget

area (1:1 ratio of areas).For wetland areas, runoff exposure is estimated as channelized runoff.

In the model, channelized runoff is the amount of pesticide that runs off of a treated field 10

times the size of the area adjacent to the treated field (10:1 ratio of areas). The drift

component is calculated as 1% of applied mass (for ground spray) or 5% of applied mass (for

aerial spray). Estimated exposures through runoff plus drift and drift alone are then compared

to measures of plant survival and growth (e.g. effects to seedling emergence and vegetative

vigor) to develop RQ values.Resulting EECs are presented in Table 18. See APPENDIX G for

more information.

Table 18. Estimated Environmental Concentrations Derived from the TerrPlant Screening

Model

USE RATE

lb a.e./A

ADJACENT

UPLAND

LOADINGa

lb a.e./A

ADJACENT

LOADING TO

SEMIͲAQUATIC

AREASa

lb a.e./A

DRIFT ONLY

lb a.e./A

Aerial Spray Application

Wheat, Barley,

Triticale 0.0087 0.000522 0.001305 0.000435

Ground Spray Application

Wheat, Barley,

Triticale 0.0087 0.000174 0.000957 0.000087

a Loading is runoff plus drift

one application per season at the proposed maximum label rate for wheat (0.0086 lb a.e./A)
57

C. Ecological Effects Characterization

Because halauxifenͲmethyl is a synthetic analogue of auxin, a plant growth hormone, effects on

aquatic animals are expected to be limited. The applicant has submitted a battery of studies, as

required by CFR 40 Part 158 that examine the toxicity of halauxifenͲmethyl and a few of the

degradates to representative aquatic organisms that serve as surrogates for organisms that

may be exposed. Both acute and chronic effects were determined for freshwater fish and

invertebrates. Acute effects on marine/estuarine fish and invertebrates and aquatic vascular

and nonvascular plants were also examined.

Based on the available data, halauxifenͲmethyl is classified as moderately toxic to practically

nonͲtoxic for freshwater and estuarine/marine fish, aquaticͲphase amphibians, freshwater and

estuarine/marine invertebrates, birds, mammals, and terrestrial invertebrates on an acute

exposure basis.

Chronic toxicity studies in freshwater fish resulted in statistically significant (ɲ=0.05) effects at

0.259 mg a.i./L based on effects on postͲhatch survival, and length, egg hatchability, and clinical

signs of toxicity. Additional data provided in a study that followed the OCSPP 890.1350 FSTRA

study resulted in statistically significant effects to fecundity (60% reduction) and fertilization

(9% reduction) reported at 0.24 mg a.i./L and a statistically significant reduction in fertilization

success at 0.077 mg a.i./L, therefore the NOAEC for this study is 0.022 mg a.i./L. Chronic toxicity

data for estuarine/marine fish resulted in a NOAEC of 0.00272 mg a.i./L based on statistically

significant reductions of length at 0.00569 mg a.i./L. Additional effects to reproduction were

observed at 0.02 mg a.i./L.

Chronic exposures in freshwater invertebrates resulted in a NOAEC of 0.144 mg a.i./L based on

effects to survival, days to first brood, number of young per surviving adult, and adult length. In

estuarine/marine invertebrates the chronic exposure resulted in a NOAEC of 0.152 mg a.i./L

based on parental generation survival at 14 days (preͲpairing), male length at 14 days, male and

female length at 28 days, days to first brood, and number of young per female.

Chronic exposure in birds resulted in a statistically significant reduction (9%) in the number of

hatched 3Ͳweek embryos NOAEC = 403 mg a.i./kgͲdiet). In mammals, chronic exposure in

females resulted in decreased body weights, decreased body weight gains and food

consumption during late gestation/early lactation (NOAEL = 103 mg a.i./kgͲbw).

Aquatic Amphibians and AquaticͲphase Terrestrial Amphibians:

Based on the available acute data on the African Clawed Frog (Xenopus laevis), there were

mortalities (45% mortality) that were statistically significant at the highest concentration tested

(at 1.75 mg a.i/L); the NOAEC in this acute exposure study was 0.924 mg a.i./L based on

mortality. The most sensitive chronic endpoint, based on an OCSPP 890.1100 Amphibian

Metamorphosis Assay, was a 11% decrease in Hind Limb Length (HLL) at 0.02 mg a.i./L, the
58

lowest concentration tested; additional significant effects were reported at 0.38 mg a.i./L (4%

decrease in Snout Vent Length (SVL)) after 21Ͳdays of exposure.

Aquatic Plants:

The most sensitive aquatic vascular plant tested with halauxifenͲmethyl was the Eurasian

watermilfoil, Myriophyllum spicatum, with an IC50 value of 0.000135 mg a.i./L and a NOAEC

value <0.0000617 mg a.i./L based on a reduction in yield based on shoot length. Results from

another study with this taxon using XDEͲ729 acid derived similar endpoints. Based on the

available data, nonͲvascular aquatic plants are much less sensitive to halauxifenͲmethyl, XDEͲ

729 acid, X11449757, and X11406790.

Terrestrial and SemiͲAquatic Plants:

For terrestrial and semiͲaquatic plants several formulation and degradate studies were

submitted. These submitted studies provide a number of endpoints showing that halauxifenͲ

methyl formulations, at least those without a chemical safener included, and the degradate

XDEͲ729 acid are highly toxic to terrestrial and semiͲaquatic plants from the onset of seed

germination through plant maturation phases captured in the seedling emergence and

vegetative vigor studies. Reproductive risks to plants are not currently evaluated. Effects from

multiple applications are also not assessed at this time. Given the persistence of halauxifenͲ

methyl, XDEͲ729 acid, the other degradates, and the effect on terrestrial plants, risk to some

plant species may be underestimated. The endpoints selected for evaluating the risk to plants

are provided in Table 19 below, however a full crossͲspecies and formulation comparison is

available in the terrestrial plant toxicity section below.

For formulation GFͲ2685, the most sensitive monocot was onion in the seedling emergence and

vegetative vigor studies, the IC25 values were 0.000394 lb a.e/acre (NOAEC = 0.000111 lb a.e./A)

and 0.000128 lb/acre (IC05 = 0.000139 lb a.e./A), respectively. Onion was also the most sensitive

taxon tested with formulation GFͲ2687, the IC25 values were 0.000767 lb a.e/acre (NOAEC =

0.000534 lb a.e./A)and 0.00154 lb/acre (IC05 = 0.00111 lb a.e./A), respectively.

The dicot studies for formulation GFͲ2685 resulted in the carrot, Daucus carrota, being the

most sensitive species in the seedling emergence study based on survival (IC25 = 0.00181 lb

a.e./A, NOAEC = 0.000558 lb a.e./A). For the vegetative vigor study using GFͲ2685, the soybean,

Glycine max, was most sensitive with an IC25 of 0.0000102 lb a.e./A and a NOAEC of 0.00000872

lb a.e./A based on weight. The sunflower, Helianthus annuus, was the most sensitive species in

the seedling emergence and vegetative vigor studies using formulation GFͲ2687 with IC25 values

of 0.000185 lb a.e./acre and 0.0000104 lb. a.e./A respectively for reduced growth (height). The

seedling emergence study had a corresponding NOAEC of 0.000133 lb a.e./acre. In the

vegetative vigor study the NOAEC was not determined so the IC05 value (0.000000095 lb a.e./A)

is used.
59

Table 19. Summary of Specific Assessment Endpoints for Animals and Plants Considered in

this Assessment for Estimating Risks to NonͲtarget Taxaa

TAXA MEASURE OF EFFECT

Survival, growth and/

or reproduction of: Species Toxicity Endpoint

Freshwater Fish

Acute

Oncorhynchus mykiss

Rainbow trout

LC50 = 2.01 mg a.i./L Mortality

Chronic

Pimephales promelas

Fathead minnow

NOAEC valueb = 0.022 mg

a.i./L Reproduction

FreshwaterͲPhase

Amphibians

Acute

Xenopus laevis

African Clawed Frog LC50 = >1.75 mg a.i./L Mortality

Chronic

Xenopus laevis

African Clawed Frog

NOAEC valuec = 0.02 mg

a.i./L Growth and Development

Freshwater

Invertebrates

Acute

Daphnia magna

Waterflea EC50 = 2.12 mg a.i./L Mortality/immobility

Chronic

Daphnia magna

Waterflea NOAEC = 0.144 mg a.i./L Survival/Reproduction

Estuarine/Marine Fish

Acute

Cyprinodon variegates

Sheepshead minnow LC50 = >1.33 mg a.i./L No effects at the highest

concentration tested.

Chronic

Cyprinodon variegates

Sheepshead minnow NOAEC = 0.00276 mg a.i./L Standard lengthreduction

Estuarine/Marine

Invertebrates

Acute

Americamysis bahia

Mysid LC50 >1.3 mg/L Mortality,45 % at 1.3 mg

a.i./L

Chronic

Americamysis bahia

Mysid NOAEC = 0.152 mg a.i./L Survival andReproduction

Aquatic Vascular

Plants

Acute

Myriophyllum spicatum

Eurasian Watermilfoil IC50 = 0.000135 mg a.i./L Reduction in Stem Yield

Listed

Myriophyllum spicatum

Eurasian Watermilfoil

NOAEC < 0.0000617 mg

a.i./L

IC05 = 0.000008 mg a.i./L

Reduction in Stem Yield

Aquatic NonͲVascular

Plants

Acute

Skeletonema costatum

Marine Diatom IC50 = 1.28 mg a.i./L Reduction in biomass

Listed

Skeletonema costatum

Marine Diatom NOAEC 0.468 mg a.i./L Reduction in biomass

Birds

Acute

Colinus virginianus

Northern bobwhite quail

LC50 = >4,858 mg/kgͲdiet

LD50 = >2,250 mg/kgͲbw Mortality
60

Chronic

Colinus virginianus

Northern bobwhite quail NOAEC = 403 mg a.i./kgͲdiet Reduced number ofhatched 3Ͳweek embryos

Mammals

Acute

Rattus Norvegicus

Norway Rat LD50 = >5,000 mg a.i./kgͲbw Mortality

Chronic

Rattus Norvegicus

Norway Rat NOAEL = 103 mg a.i./kgͲbw

Based on decreased body

weights, decreased body

weight gains and food

consumption during late

gestation/early lactation

Terrestrial

Invertebrates

Acute

Apis mellifera

Honey Bee

LD50 = >98.1 μg/bee

(contact)

LD50 = 108.0 μg/bee (oral)

Mortality

Terrestrial Plants

Formulation

GFͲ2685

NonͲlisted (Seedling Emergence)

Monocot: 

Allium cepa

Onion

IC25 =0.00394 lb a.e./acre Reduced Fresh Weight

Dicot:

Daucus carota

Carrot

IC25 = 0.00181 lb a.e./acre Survival

Listed (Seedling Emergence)

Monocot: 

Allium cepa

Onion

NOAEC = 0.00111 lb

a.e./acre

Reduced Fresh Weight

Dicot:

Daucus carota

Carrot

NOAEC = 0.000558 lb

a.e./acre

Survival

NonͲlisted (Vegetative vigor)

Monocot: 

Allium cepa

Onion

IC25 =0.000128 lb a.e./acre Reduced Fresh Weight

Dicot:

Glycine max

Soybean

IC25 = 0.0000102 lb

a.e./acre

Listed (Vegetative vigor)

Monocot: 

Allium cepa

Onion

IC05 = 0.0000122 lb a.e./A Reduced Fresh Weight

Dicot:

Glycine max

Soybean

NOAEC = 0.00000872 lb

a.e./A

Terrestrial Plants

Formulation

GFͲ2687

NonͲlisted (Seedling Emergence)

Monocot: 

Allium cepa

Onion

IC25 = 0.000767 lb a.e./acre Reduced Fresh Weight

Dicot:

Helianthus annuus

Sunflower

IC25 = 0.0000104 lb

a.e./acre

Reduced Height
61

D. Aquatic Effects Characterization

Aquatic Animals

Aquatic animal toxicity studies for halauxifenͲmethyl are summarized in Table 20.

Table 20. Submitted Toxicity Data for HalauxifenͲmethyl and Aquatic Animals

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

FRESHWATER FISH

Acute

Rainbow trout

(Oncorhynchus

mykiss)

96Ͳhr LC50 =

2.01 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557747 Acceptable

NOAEC = 0.786 mg

a.i./L

based on mortality and

sublethal effects (fish

on bottom and fish

surfacing) at 1.50 mg

a.i./L.

Listed (Seedling Emergence)

Monocot: 

Allium cepa

Onion

NOAEC = 0.000534 lb

a.e./acre

Reduced Fresh Weight

Dicot:

Helianthus annuus

Sunflower

NOAEC = 0.000133 lb

a.e./acre

Reduced Height

NonͲlisted (Vegetative vigor)

Monocot: 

Allium cepa

Onion

IC25 =0.00154 lb a.e./acre Reduced Fresh Weight

Dicot:

Helianthus annuus

Sunflower

IC25 = 0.0000104 lb

a.e./acre

Listed (Vegetative vigor)

Monocot: 

Allium cepa

Onion

NOAEC = 0.00111 lb a.e./A Reduced Fresh Weight

Dicot:

Helianthus annuus

Sunflower

IC05 = 0.000000095 lb a.e./A

a

All endpoints are the most sensitive for that taxon and were derived from halauxifenͲmethyl or formulation

based studies (terrestrial plants). b

This study followed an OCSPP 890.1350 guideline. The study design is not appropriate for designating a NOAEC

however in this case there were statistically significant and biologically meaningful effects at the next highest

concentration. This “NOAEC value” will be used in risk characterization only. c

This study followed an OCSPP 890.1100 guideline. The study design is not appropriate for designating a NOAEC

however in this case there were statistically significant and biologically meaningful effects at the next highest

concentration. This “NOAEC value” will be used in risk characterization only.
62

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

Fathead

minnow

(Pimephales

promelas)

96Ͳhr LC50 >3.22

mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557748 Acceptable

NOAEC = 1.73 mg a.i./L

based on statistically

significant effects on

mortality and sublethal

effects (loss of

equilibrium and fish on

bottom of the test

chamber) at 3.22 mg

a.i./L.

Chronic

Fathead

minnow

(Pimephales

promelas)

NOAEC:

0.259 mg a.i./L

LOAEC:

0.536 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557756 Acceptable

NOAEC = 0.259 mg

a.i./L is based on effects

on postͲhatch survival,

and standard length,

egg hatchability, and

clinical signs of toxicity.

Fathead

minnow

(Pimephales

promelas)

Most Sensitive

Apical

Endpoints

(statistically

significant):

0.24 mg a.i./L

treatment

level:

Ͳ60% reduction

in fecundity

Ͳ9.3%

reduction in

fertilization

success

0.077 mg a.i./L

treatment

level:

Ͳ2.5 %

reduction in

fertilization

success (2.5%)

in the 0.077

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557867 Acceptable

Study Followed OCSPP

890.1350 Guideline.

No statistically

significant effects to

apical endpoints at

0.022 mg a.i./L.

Survival:

No mortalities were

observed at highest

test concentration 0.24

mg a.i./L

Fertility and Fecundity:

No effects to apical

endpoints (fertility or

fecundity) were

observed at 0.022 mg

a.i./L

Female GSI:

No significant effects at

0.077 mg a.i./L. There

was a statistically

significant increase in

female GSI compared

to the negative control

in the 0.24 mg a.i./L

treatment groups (30%;

p<0.05)

Female Plasma VTG:
63

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

No significant effects at

0.022 mg a.i./L. There

were statistically

significant increases in

plasma VTG (34%) in

the 0.24 mg ai/L

treatment group

(p<0.05) and in the

0.077 mg a.i./L

treatment group (40%;

p=0.06).

ESTUARINE/MARINE FISH

Acute

Sheepshead

minnow

(Cyprinodon

variegatus)

96Ͳhr LC50

>1.33 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557749 Acceptable

NOAEC = 1.33 mg a.i./L

(the highest

concentration tested)

Chronic

Sheepshead

minnow

(Cyprinodon

variegatus)

NOAEC:

0.00272 mg

a.i./L

LOAEC:

0.00569 mg

a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557759 Acceptable

NOAEC = 0.00272 mg

a.i./L

based on statistically

significant reduction of

standard length at

0.00569 mg a.i./L

PostͲhatch survival

effects were also

significant at the 0.022

mg a.i./L treatment

level, NOAEC = 0.0115

mg a.i./L

FRESHWATER INVERTEBRATES

Acute

Water flea

(Daphnia

magna)

48Ͳhr EC50 =

2.12 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557741 Acceptable

NOAEC = 0.821 mg

a.i./L is based on

immobility at the next

highest concentration.

Chronic

Water flea

(Daphnia

magna)

Mortality/Immo

bility

21Ͳday EC50:

1.18 mg a.i./L

Reproduction

21Ͳday EC50:

0.706 mg a.i./L

NOAEC:

0.144 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557753 Acceptable

NOAEC = 0.144 mg

a.i./L

endpoints affected:

survival, days to first

brood, young per

surviving adult, and

length.
64

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

LOAEC:

0.279 mg a.i./L

Midge Larvae

(Chironomus

dilutus)

10Ͳday

Endpoints

Overlying

Water:

EC50 > 0.11mg

a.i./L

NOAEC = 0.11

mg a.i./L

Pore Water:

EC50 > 5.64 mg

a.i./L

NOAEC = 5.64

mg a.i./L

Sediment:

EC50 > 99.0 mg

a.i./kg

NOAEC = 99.0

mg a.i./kg



HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557761 Acceptable

U.S. EPA OCSPP

Guideline 850.1735

No effects observed in

study

Other Endpoints

(NOAEC/EC50):

XDEͲ729 acid: Overlying

Water

0.31/>0.31 mg a.i./L

Sediment

3.6/>3.6 mg a.i./kg

TTR

Overlying Water

0.42/>0.42 mg a.e./L

Sediment

98.2/>98.2 mg a.e./kg

Midge Larvae

(Chironomus

dilutus)

28Ͳday

Endpoints

Overlying

Water:

EC50 > 0.47 mg

a.i./L

NOAEC = 0.47

mg a.i./L

Pore Water:

EC50 > 0.02 mg

a.i./L

NOAEC = 0.02

mg a.i./L

Sediment:

EC50 > 2.82 mg

a.i./kg

NOAEC = 2.82

mg a.i./kg



HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557885 Acceptable

U.S. EPA OCSPP

Guideline 850.1735

No effects observed in

study

Other Endpoints

(NOAEC/EC50):

XDEͲ729 acid: Overlying

Water

0.62/>0.62 mg a.i./L

Pore Water

0.24/>0.24 mg a.i./L

Sediment

0.82/>0.82 mg a.i./kg

TTR

Overlying Water

1.08/>1.08 mg a.e./L

Pore Water

0.26/>0.26 mg a.e./L

Sediment

3.51/>3.51 mg a.e./kg

ESTUARINE/MARINE INVERTEBRATES
65

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

Acute

Mysid

(Americamysis

bahia)

96Ͳhr LC50

>1.3 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557746

Supplemental

Ͳqualitative

use only

NOAEC = 0.671 mg

a.i./L is based on 40%

mortality in the 1.3 mg

a.i./L treatment.

The study was classified

as supplemental due to

a nonͲdefinitive

endpoint and

uncertainty

surrounding the value

of a definitive endpoint

(mortality was 40% at

the highest test

concentration (limit of

solubility in the test

medium).

Eastern oyster

(Crassostrea

virginica)

96Ͳhr EC50

1.29 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557745

Supplemental

Ͳqualitative

use only

NOAEC = 0.260 mg

a.i./L based on a 22%

inhibition of shell

growth at 0.433 mg

a.i./L.

The study was classified

as supplemental

because the study

began only after 3 days

of oyster acclimation

(recommended 15

days), and a biologically

significant stimulatory

solvent effect (19%

increase compared to

the negative control)

had been detected and

likely muted the toxic

effect of the test

material.

Marine

Amphipod

(Leptocheirus

plumulosus).

10Ͳday

Endpoints

Overlying

Water:

EC50 > 0.17 mg

a.i./L

NOAEC = 0.17

mg a.e./L

Pore Water:

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557762 Acceptable

U.S. EPA OCSPP

Guideline 850.1740

No effects observed in

study

Other Endpoints

(NOAEC/EC50):

XDEͲ729 acid: Overlying

Water
66

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

EC50 > 0.39 mg

a.i./L

NOAEC = 0.39

mg a.i./L

Sediment:

EC50 > 36.1 mg

a.i./kg

NOAEC = 36.1

mg a.i./kg



1.21/>1.21 mg a.i./L

Pore Water

3.79/>3.79 mg a.i./L

Sediment

10.5/>10.5 mg a.i./kg

TTR

Overlying Water

1.37/>1.37 mg a.e./L

Pore Water

4.16/>4.16 mg a.e./L

Sediment

45.0/>45.0 mg a.e./kg

Chronic

Mysid

(Americamysis

bahia)

NOAEC:

0.152 mg a.i./L

LOAEC:

0.325 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557755 Acceptable

NOAEC = 0.152 mg

a.i./L is based on

parental generation

survival at 14 days (preͲ

pairing), male length at

14 days, male and

female length at 28

days, days to first

brood, and number of

young per female.

AQUATIC PHASE AMPHIBIANS

Acute

African Clawed

Frog (Xenopus

laevis)

96Ͳhour

Survival:

LC50 > 1.75

NOAEC:

0.924 mg a.i./L

LOAEC:

1.75 mg a.i./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557884 Acceptable

96Ͳhour study

conducted on tadpoles

(NF Stage 47Ͳ50, 8 days

post hatch) under flowͲ

through conditions.

Survival: 45% of the

tadpoles died at the

1.75 mg a.i./L

treatment level (50%

and 40 % survival

within the two

replicates at that

treatment level).

Sublethal Effects:

Discoloration, loss of

equilibrium, erratic

swimming, and

surfacing observed at

the 0.924 mg a.i,/L and

1.75 mg a.i./ treatment

levels.

Chronic
67

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

African Clawed

Frog (Xenopus

laevis)

7Ͳday Most

Sensitive

Endpoints:

19% decrease in

wet weight at

0.38 mg a.e./L

5% and 7%

decrease in SVL

in 0.094 and

0.38 mg a.e./L

test

concentrations

21Ͳday Most

Sensitive

Endpoints:

11% decrease in

HLL at 0.02 mg

a.e./L, the

lowest

concentration

tested.

4% decrease in

SVL in highest

test

concentration

0.38 mg a.e./L

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557866 Supplemental– qualitative

Study Followed OCSPP

890.1100 Guideline.

This study was

classified as

supplemental due to

significant solvent

effects and control

mortality.

The solvent control

(DMF) caused a

statistically significant

stimulatory effect

compared to the

negative control.

All statistics were run in

comparison to the

negative control as well

as against the solvent

control.

.

Results from

comparisons made

against the solvent

control are provided

here.

Acute Toxicity of HalauxifenͲmethyl

Fish and AquaticͲphase Amphibians

The freshwater fish test species, rainbow trout (Oncorhynchus mykiss; a surrogate for coldwater

vertebrates) and fathead minnow (Pimephales promelas; a surrogate for warmwater

vertebrates) were evaluated in 96Ͳhour acute toxicity tests. In the rainbow trout test (MRID

46235814), 100% of the fish died within 24Ͳhrs when exposed to the highest tested

concentration (3.10 mg a.i./L) and 10% mortality after 48Ͳhrs at 1.50 mg a.i./L. The study also

reported statistically significant sublethal effects (60% of fish on bottom, 10% surfacing) at the

1.50 mg a.i./L test concentration. In the acute test with fathead minnow (MRID 48557748), 30%

of the fish died within 24Ͳhrs when exposed to the highest tested concentration (3.22 mg

a.i./L). No other mortalities occurred in the study. The study also reported statistically

significant sublethal effects (43% of fish on bottom, 57% with a loss of equilibrium) at the 3.22

mg a.i./L test concentration. Therefore, the most sensitive LC50 value for freshwater fish is 2.01

mg a.i./L based on the rainbow trout study, and halauxifenͲmethyl is classified as moderately

toxic to freshwater fish on an acute exposure basis (Table 20).
68

A nonͲguideline 96Ͳhour static acute toxicity study of an amphibian species, the African Clawed

Frog (Xenopus laevis) larvae, was also submitted (MRID 48557884). The LC50 value exceeds 1.75

mg a.i./L (the highest concentration tested); however, 45% of the tadpoles died at the 1.75 mg

a.i./L treatment level. Sublethal effects observed in the study included discoloration, loss of

equilibrium, erratic swimming, and surfacing at the 0.924 mg a.i,/L and 1.75 mg a.i./L treatment

levels. Therefore on an acute exposure basis, halauxifenͲmethyl is classified as most moderately

toxic to aquaticͲphase amphibians.

The preferred estuarine/marine fish test species, sheepshead minnow (Cyprinodon variegatus;

MRID 48557749) was evaluated in 96Ͳhour acute limit toxicity test. The 96Ͳhour LC50 value

exceeds 1.33 mg a.i./L (Table 20). No mortality or sublethal effects were observed. HalauxifenͲ

methyl is classified as moderately toxic to estuarine/marine fish on an acute exposure basis.

Aquatic Invertebrates

An acute study on midge larvae (Chironomus dilutus) had no reported effects in the study up to

1.08 mg TTR/L in water and 3.51 mg a.e./L in sediment (MRID 48557761). Another study used

the waterflea (Daphnia magna) to estimate toxicity to freshwater invertebrates. The acute

toxicity test under static conditions with waterfleas (MRID 48557741) resulted in a 48Ͳhour EC50

= 2.12 mg a.i./L (Table 12). Immobilization was 100% in the 3.23 mg a.i./L treatment group.

HalauxifenͲmethyl is classified as moderately toxic to freshwater invertebrates on an acute

exposure basis.

An acute study on marine amphipods (Leptocheirus plumulosus).had no reported effects in the

study up to 1.37 mg a.i./L in overlying water and up to 45.0 mg a.e./kg in sediment (MRID

48557762). Acute toxicity testing of estuarine/marine invertebrates was conducted using the

mysid shrimp (Americamysis bahia) and Eastern oyster (Crassostrea virginica). In a 96Ͳhour

acute toxicity study of mysid shrimp (MRID 48557746), the NOAEC (0.671 mg a.i./L) is based on

40% mortality in the 1.3 mg a.i./L treatment group, the limit of solubility. There were no subͲ

lethal effects reported. The 96Ͳhour LC50 value exceeds 1.3 mg a.i./L (Table 20), and halauxifenͲ

methyl is classified at most as moderately toxic to the estuarine/marine mysids on an acute

exposure basis. In the 96Ͳhour acute shell deposition toxicity study of Eastern oysters (MRID

48557745), the EC50 value was 1.29 mg a.i./L, and the NOAEC (0.260 mg a.i./L) is based on a

22% inhibition of shell growth at 0.433 mg a.i./L (Table 20). HalauxifenͲmethyl is classified as

moderately toxic to the estuarine/marine mollusk on an acute exposure basis.

Chronic Toxicity of HalauxifenͲmethyl

Aquatic vertebrates

A freshwater fish early life stage study on fathead minnow (Pimephales promelas) resulted in a

NOAEC of 0.259 mg a.i./L, (MRID 48557756) based on effects on postͲhatch survival, standard

length, egg hatchability, and clinical signs of toxicity at the 0.536 mg a.i./L test concentration.
69

A Fish ShortͲterm Reproduction Assay (FSTRA) with the fathead minnow (Pimephales promelas,

OCSPP Guideline 890.1350) was also submitted (MRID 48557867). There were no mortalities in

the study however there were a number of effects related to reproduction reported. There

were statistically significant reductions in fecundity (60%) and fertility (9.3%) compared to the

negative control in the 0.24 mg a.i./L treatment group, and a significant reduction in

fertilization success (2.5%) in the 0.077 mg a.i./L treatment group. There was also a statistically

significant increase in female gonadosomatic index (GSI)compared to the negative control in

the 0.022 mg a.i./L and 0.24 mg a.i./L treatment groups (29% and 30% respectively). There were

also statistically significant increases in plasma vitellogenin (VTG) in the 0.24 mg a.i./L (34%) and

0.077 mg a.i./L treatment groups (40%). There were no other statistically significant differences

in any other endpoint (p>0.05).There were no statistically significant differences (p>0.05)

between histopathology severity scores or gonadal stages in treated groups compared to the

negative controls.

Therefore, the NOAEC of 0.022 mg a.i./L from the fathead minnow study (MRID 48557867) will

be used to assess the risk of halauxifenͲmethyl to freshwater fish based on chronic exposure to

halauxifenͲmethyl.

An estuarine/marine fish early life stage study on sheepshead minnow (Cyprinodon variegatus)

resulted in a NOAEC of 0.00272 mg a.i./L, (MRID 48557759) based on statistically significant

reductions of standard length (7%) at the 0.00569 mg a.i./L test concentration. There were also

statistically significant effects on postͲhatch survival observed at the 0.022 mg a.i./L treatment

level (NOAEC = 0.0115 mg a.i./L). Therefore, a NOAEC of 0.00272 mg a.i./L will be used to assess

the risk of halauxifenͲmethyl to estuarine/marine fish based on chronic exposure.

An amphibian metamorphosis study (OCSPP 890.1100, MRID 48557866) was submitted. In this

study the solvent control (DMF) caused a statistically significant stimulatory effect compared to

the negative control, so all statistics were run in comparison to the negative control as well as

against the solvent control. Statistically significant differences between treatment groups were

detected for a number of the endpoints when comparing to the solvent controls, but these

effects were not statistically significant when compared to the negative controls. It appears that

the stimulatory effect that was manifested in the presence of the solvent masked the effects

when comparing to the negative controls. This study was determined to be supplemental and

only for qualitative use because of the solvent interference in addition to mortalities in the

solvent control (1 death), the 0.02 mg a.i./L (2 deaths) and the highest concentration 0.38 mg

a.i./L (1 death). Results from comparisons made against the solvent control are provided here.

The most sensitive endpoints include a 19% decrease in wet weight at 0.38 mg a.i./L, and 5%

and 7% decrease in snout vent length in 0.094 and 0.38 mg a.i./L test concentrations after 7Ͳ

days of exposure. The most sensitive endpoint after 21Ͳdays of exposure were a 11% decrease

in HLL at 0.02 mg a.i./L, the lowest concentration tested,and a 4% decrease in SVL in highest

test concentration 0.38 mg a.i./L.
70

Aquatic Invertebrates

A chronic exposure sediment study on midges (Chironomus dilutus) reported no effects from

exposure to halauxifenͲmethyl or XDEͲ729 acid in the study (MRID 48557885). A 21Ͳday staticͲ

renewal freshwater invertebrate life cycle test using the waterflea (Daphnia magna) (MRID

48557753) was provided. The study reported that 100% of the daphnids died in the highest test

concentration (1.63 mg a.i./L) and 90% survival at the next lower test concentration (0.920 mg

a.i./L) and resulted in the 21Ͳday EC50 for mortality of 1.18 mg a.i./L. There were also significant

decreases in the number of live offspring per living adult resulting in an EC50 of 0.706 mg a.i./L

and a NOAEC of 0.144 mg a.i./L for reproduction. Therefore, a NOAEC of 0.144 mg a.i./L will be

used to assess the risk of halauxifenͲmethyl to freshwater invertebrates based on chronic

exposure (Table 20).

A 21Ͳday staticͲrenewal estuarine/marine invertebrate life cycle test using mysid (Americamysis

bahia) (MRID 48557755) was also provided. Following 14 days of exposure (prior to pairing),

mean survival was 82% in the 1.27 mg a.i./L treatment level. The difference was statisticallyͲ

significant compared to the negative control at the 1.27 mg a.i./L level. No treatmentͲrelated

effects on postͲpairing survival were observed. After 14 days, there was a statistically significant

difference in the lengths of PͲgeneration male mysids compared to the negative control at the

1.27 mg a.i./L level. Lengths of PͲgeneration female mysids after 14 days showed no

statisticallyͲsignificant differences indicated at any level compared to the control. After 28 days

the lengths of the PͲgeneration male and female mysids were statisticallyͲsignificant at the

ш0.325 mg a.i./L level. The mean time to first brood release, and mean number of total young

produced per female were statistically significant at the 1.27 mg a.i./L level. Mean survival of F1

mysids was evaluated for all but the highest treatment level (i.e., 1.27 mg a.i./L) as the majority

of offspring from this level were not greater than 3 days old before Day 28 of the study, and

none had reached 7 days old.This was due to a delay in PͲgeneration sexual maturity at the

highest treatment level. No treatmentͲrelated effect on F1 survival was indicated at the

remaining treatment levels. No treatmentͲrelated effect on 9Ͳday F1 body lengths were

detected by the study author up to and including the 0.646 mg a.i./L level. The overall NOAEC

and LOAEC is 0.152 and 0.325 mg a.i./L, respectively, based on growth (i.e., 28Ͳday body length)

of PͲgeneration male and female mysids.

Degradate Toxicity to Aquatic Animals

Based on the submitted studies summarized in Table 21, halauxifenͲmethyl degradates are

classified as practically nontoxic to freshwater and estuarine/marine fish and invertebrates on

an acute exposure basis. There were no mortalities or sublethal effects at the highest treatment

levels tested in most of the acute studies and all of the LC50 or EC50 endpoints for aquatic

animals are ‘greater than’ values. These ‘greater than’ endpoints are not used to calculate RQ

values; however, the endpoints are used to help characterize potential risk in the Risk

Description section of this assessment.
71

Table 21. Submitted Toxicity Data for HalauxifenͲmethyl Transformation Products and Aquatic

Animals

TAXON ENDPOINT TEST

SUBSTANCE MRID

STUDY

CLASSͲ

IFICATION

COMMENTS

FRESHWATER FISH

Acute

Rainbow trout

(Oncorhynchus

mykiss)

96Ͳhr LC50

>107 mg a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557750 Acceptable

NOAEC = 107 mg

a.i./L (highest

concentration tested)

Rainbow trout

(Oncorhynchus

mykiss)

96Ͳhr LC50

>124 mg a.i./L

X11449757

TGAI (98.6% a.i.) 48557751 Acceptable

NOAEC = 124 mg

a.i./L

(highest

concentration tested)

Rainbow trout

(Oncorhynchus

mykiss)

96Ͳhr LC50

>29 mg a.i./L

X11406790

TGAI (95% a.i.) 48557752 Acceptable

NOAEC = 29 mg a.i./L

(highest

concentration tested)

Chronic

Fathead

minnow

(Pimephales

promelas)

NOAEC:

12mg a.i./L

LOAEC:

>12 mg a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557868 SupplementalQuantitative

Study Followed

OCSPP 890.1350

Guideline.

No observed frank or

sublethal effects in

study.

Fathead

minnow

(Pimephales

promelas)

NOAEC:

11.8 mg a.i./L

LOAEC:

>11.8 mg a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557757 Acceptable

NOAEC = 11.8 mg

a.i./L (the highest

concentration tested)

Fathead

minnow

(Pimephales

promelas)

NOAEC:

8.9 mg a.i./L

LOAEC:

>8.9 mg a.i./L

X11449757

TGAI (97% a.i.) 48557758 Acceptable

NOAEC = 8.9 mg a.i./L

(highest

concentration tested)

FRESHWATER INVERTEBRATES

Acute

Water flea

(Daphnia

magna)

48Ͳhr EC50

>106 mg a.i./L

XDEͲ729 acid

TGAI (97.2% a.i.) 48557742 Acceptable

NOAEC = 106 mg

a.i./L (the highest

concentration tested)

Water flea

(Daphnia

magna)

48Ͳhr EC50

>115 mg a.i./L

X11449757

TGAI (98.6% a.i.) 48557743 Acceptable

NOAEC = 115 mg

a.i./L

(highest

concentration tested)

Water flea

(Daphnia

magna)

48Ͳhr EC50

>25 mg a.i./L

X11406790

TGAI (95% a.i.) 48557744 Acceptable

NOAEC = 25 mg a.i./L

(highest

concentration tested)

Chronic
72

TAXON ENDPOINT TEST

SUBSTANCE MRID

STUDY

CLASSͲ

IFICATION

COMMENTS

Water flea

(Daphnia

magna)

21Ͳday EC50:

Mortality/Immobility

>98.3 mg a.i./L

Reproduction >98.3

mg a.i./L

NOAEC:

98.3 mg a.i./L

LOAEC:

>98.3 mg a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557754 Acceptable

NOAEC = 98.3 mg

a.i./L (the highest

concentration tested)

Aquatic Plants

Aquatic plant toxicity studies for halauxifenͲmethyl are summarized in Table 22.

Table 22. Submitted Toxicity Data for HalauxifenͲmethyl and Aquatic Plants

TAXON ENDPOINT TEST SUBSTANCE MRID

STUDY

CLASSͲ

IFICATION

COMMENTS

AQUATIC VASCULAR PLANTS

Duckweed (Lemna

gibba)

Frond

Number

Yield IC50 =

3.58 mg

a.i./L

NOAEC =

0.491 mg

a.i./L

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557771 Acceptable

LOAEC = 1.03 mg a.i./L

based on reduced frond

growth rate and yield

Necrosis of fronds was

observed in all test

concentrations

Eurasian

watermilfoil

(Myriophyllum

spicatum)

14ͲDay

Total Shoot

Length Yield

IC50 =

0.000135

mg a.i./L

NOAEC

< 0.000062

mg a.i/L

IC05 =

0.000008

mg a.i/L

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557886 Supplemental

The test was performed

based on the draft

AMRAP Method

(MALTBY et al.

2010): Growth

Inhibition Test for the

Rooted Aquatic

Macrophyte,

Myriophyllum sp.,

submitted to OECD for

evaluation, 2011.

There was a 16%

reduction in total shoot

length yield reported at

the 0.000062 mg a.i/L (p

= 0.06), therefore the

IC05 will be used.
73

TAXON ENDPOINT TEST SUBSTANCE MRID

STUDY

CLASSͲ

IFICATION

COMMENTS

AQUATIC NONͲVASCULAR PLANTS

Cyanobacteria

(Anabaena flosͲ

aquae)

IC50 > 2.62

mg a.i./L

NOAEC =

2.62 mg

a.i./L

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557778 Acceptable No endpoints affected.

Green Algae

(Pseudokirchneriella

subcapitata)

IC50 > 2.6

mg a.i./L

NOAEC =

2.6 mg a.i./L

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557775 Acceptable No endpoints affected.

Marine Diatom

(Skeletonema

costatum)

Biomass

IC50 = 1.28

mg a.i./L

NOAEC =

0.469 mg

a.i./L

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557779 Acceptable

LOAEC = 0.939 mg a.i./L

based on reduced

biomass

NOAEC/LOAEC based on

Growth Rate and Yield =

0.241 and 0.469 mg

a.i./L respectively

Freshwater Diatom

(Navicula

pelliculosa)

Biomass

IC50 = 1.87

mg a.i./L

NOAEC =

0.233 mg

a.i./L

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557777 Acceptable

LOAEC = 0.458 mg a.i./L

based on reduced

biomass

The IC50 for duckweed, based on reduced yield (frond number) in a 7Ͳday toxicity study, is 3.58

mg a.i./L (MRID 48557771). In this study the associated NOAEC was 0.491 mg a.i./L, based on

reduced frond yield and reduced growth rate. In a study with Eurasian watermilfoil (MRID

48557886), the total shoot length yield resulted in an IC50 of 0.000135 mg a.i./L. There was a

16% reduction in total shoot length yield reported at the 0.000062 mg a.i/L (p = 0.06), so the

IC05 (0.000008 mg a.i/L) will be used to calculate RQs for listed aquatic vascular plants.

Therefore, an IC50 value of 0.000135 mg a.i./L and a IC05 0.000008 mg a.i/L will be used to assess

the risk of halauxifenͲmethyl to vascular aquatic plants (macrophytes).

Toxicity tests using nonvascular aquatic plants resulted in 96Ͳhour IC50 values ranging from 1.28

mg a.i./L for reductions in biomass in marine diatoms (Skeletonema costatum) (MRID

48557779) to > 2.6 mg a.i./L in the Green Algae (Pseudokirchneriella subcapitata) (MRID

48557775). The lowest IC50 value of 1.28 mg a.i./L and the associated NOAEC value of 0.469 mg

a.i./L for reductions in biomass in Skeletonema costatum will be used to assess the risk of

halauxifenͲmethyl to nonvascular aquatic plants.
74

Degradate Toxicity to Aquatic Plants

Aquatic plant toxicity studies for halauxifenͲmethyl degradates are summarized in Table 23.

Table 23. Submitted Toxicity Data for HalauxifenͲmethyl Transformation Products and

Aquatic Plants

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

AQUATIC VASCULAR PLANTS

Duckweed (Lemna

gibba)

IC50 = 13.4

mg a.i./L

NOAEC =

0.501 mg

a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557772 Acceptable

LOAEC = 1.29 mg a.i./L

based on reduced

frond growth rate and

yield

Duckweed (Lemna

gibba)

IC50 > 99.5

mg a.i./L

NOAEC =

49.0 mg

a.i./L

X11449757

TGAI (98.6% a.i.) 48557773 Acceptable

LOAEC = 99.5 mg a.i./L

based on reduced

frond growth rate and

yield

Sublethal effects

noted:

Ͳchlorosis observed in

control and all

treatment levels

without clear dose

response

Ͳnecrosis observed in

control and all

treatment levels with

dose response.

Duckweed (Lemna

gibba)

IC50 >12 mg

a.i./L

NOAEC = 2.7

mg a.i./L

X11406790

TGAI (95% a.i.) 48557774 Acceptable

LOAEC = 5.4 mg a.i./L

based on reduced

frond growth rate and

yield

Sublethal effects

noted:

Ͳchlorosis observed in

middle and highest

treatment levels with

dose response

Ͳnecrosis observed in

control and all

treatment levels with

dose response.

Eurasian

watermilfoil

14ͲDay

Length (Total

XDEͲ729 acid

TGAI (95.3% a.i.) 48557887 Supplemental

The test was

performed based on

the draft AMRAP
75

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

(Myriophyllum

spicatum)

Shoot Length

Yield)

IC50 =

0.00058 mg

a.i./L

NOAEC =

0.000185 mg

a.i/L

Method (MALTBY et

al.

2010): Growth

Inhibition Test for the

Rooted Aquatic

Macrophyte,

Myriophyllum sp.,

submitted to OECD for

evaluation, 2011.

Eurasian

watermilfoil

(Myriophyllum

spicatum)

14ͲDay Yield

(Total Shoot

Length Yield)

IC50 = >0.100

mg a.i./L

NOAEC

= 0.100 mg

a.i/L

X11449757

TGAI (98.6% a.i.) 48557888 Supplemental

The test was

performed based on

the draft AMRAP

Method (MALTBY et

al.

2010): Growth

Inhibition Test for the

Rooted Aquatic

Macrophyte,

Myriophyllum sp.,

submitted to OECD for

evaluation, 2011.

No endpoints

affected.

Eurasian

watermilfoil

(Myriophyllum

spicatum)

14ͲDay Yield

(Total Shoot

Length) IC50 =

>0.100 mg

a.i./L

NOAEC

= 0.100 mg

a.i/L

X11406790

TGAI (95% a.i.) 48557889 Supplemental

The test was

performed based on

the draft AMRAP

Method (MALTBY et

al.

2010): Growth

Inhibition Test for the

Rooted Aquatic

Macrophyte,

Myriophyllum sp.,

submitted to OECD for

evaluation, 2011.

No endpoints

affected.

AQUATIC NONͲVASCULAR PLANTS

Cyanobacteria

(Anabaena flosͲ

aquae)

IC50 = 51.7

mg a.i./L

NOAEC =

26.4 mg

a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557783 Acceptable

LOAEC = 52.7 mg a.i./L

based on reduced

yield, growth rate and

biomass

Green Algae

(Pseudokirchneriella

subcapitata)

IC50 = 23.2

mg a.i./L XDEͲ729 acid

TGAI (95.3% a.i.) 48557781 Acceptable LOAEC = 13.3 mg a.i./Lbased on reduced
76

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

NOAEC =

6.60 mg

a.i./L

yield, growth rate and

biomass

Green Algae

(Pseudokirchneriella

subcapitata)

IC50 = 5.28

mg a.i./L

NOAEC =

1.15 mg

a.i./L

X11449757

TGAI (98.6% a.i.) 48557780 Acceptable

LOAEC = 2.36 mg a.i./L

based on reduced

yield, growth rate and

biomass

Green Algae

(Pseudokirchneriella

subcapitata)

Yield IC50 =

1.83 mg

a.i./L

NOAEC =

0.44 mg

a.i./L

X11406790

TGAI (95% a.i.) 48557776 Acceptable

Most Sensitive

endpoint, Yield:

LOAEC = 0.89 mg a.i./L

Biomass:

NOAEC = 0.23 mg

a.i./L

LOAEC = 0.44 mg a.i./L

Growth Rate:

NOAEC = 0.89 mg

a.i./L

LOAEC = 1.9 mg a.i./L

Marine Diatom

(Skeletonema

costatum)

IC50 = 67.1

mg a.i./L

NOAEC =

26.3 mg

a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557784

Supplemental

– suitable for

quantitative

use

LOAEC = 52.5 mg a.i./L

based on reduced

yield and biomass

Freshwater Diatom

(Navicula

pelliculosa)

IC50 = 49.6

mg a.i./L

NOAEC =

13.4 mg

a.i./L

XDEͲ729 acid

TGAI (95.3% a.i.) 48557782 Acceptable

LOAEC = 25.9 mg a.i./L

based on reduced

biomass

Toxicity tests using duckweed resulted in 96Ͳhour IC50 values ranging from 13.4 mg a.i./L to >

99.5 mg a.i./L. The most sensitive IC50 for duckweed, based on reduced yield (frond number) in

a 7Ͳday toxicity study, is 13.4 mg a.i./L (MRID 48557771) of XDEͲ729 acid. In this study the

associated NOAEC was 0.501 mg a.i./L, based on reduced frond yield and reduced growth rate.

The Eurasian watermilfoil studies showed much greater toxicity to XDEͲ729 acid than the

Lemna studies.The most sensitive endpoint was total shoot length yield (IC50 = 0.00058 mg

a.i./L, NOAEC 0.000185 mg a.i/L). Therefore, an IC50 value of 0.00058 mg a.i./L and the NOAEC

of 0.000185 mg a.i./L will be used to assess the risk of XDEͲ729 acid to vascular aquatic plants

(macrophytes).

Toxicity tests using nonvascular aquatic plants resulted in 96Ͳhour IC50 values ranging from 1.83

mg a.i./L for reductions in biomass in Green Algae (Pseudokirchneriella subcapitata)
77

(MRID 48557776) to 67.1 mg a.i./L in the Marine Diatom (Skeletonema costatum) (MRID

48557784). The lowest IC50 value of 1.83 mg a.i./L and the associated NOAEC value of 0.44 mg

a.i./L for reductions in biomass in Pseudokirchneriella subcapitata will be used to assess the risk

of halauxifenͲmethyl degradates to nonvascular aquatic plants.

E. Terrestrial Effects Characterization

Terrestrial Animals

Birds

Based on the LD50 values for the northern bobwhite quail (Colinus virginianus), and zebra finch

(Taeniopygia guttata) of >2,250 mg a.i./kgͲbw, halauxifenͲmethyl is characterized as “practically

nontoxic” to avian species on an acute oralͲexposure basis (MRIDs 47945732, 47945731, and

47945733, respectively) (see Table 24). HalauxifenͲmethyl is no more than “slightly toxic” to

avian species on a subͲacute dietaryͲexposure basis, with LC50 values of >4,858 mg/kgͲdiet

reported for northern bobwhite quail (MRID 47945735) and mallard ducks (MRID 47945734). In

this assessment, a subacute dietary LC50 value of >4,858 mg a.i./kgͲdiet and an acute oral LD50

of >2,000 mg a.i./kg body weight will be used to assess the risk of halauxifenͲmethyl to birds.

Table 24. Submitted Toxicity Data for HalauxifenͲmethyl and Birds

TAXON ENDPOINT TEST

SUBSTANCE MRID STUDY CLASSͲIFICATION COMMENTS

Acute Oral

Bobwhite

quail (Colinus

virginianus)

14Ͳday LD50

>2,250 mg

a.i./kgͲbw

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557763 Acceptable

Male and Female

NOAEL = 2250 mg a.i./kgͲ

bw (the limit dose) no

mortalities or signs of

toxicity were observed in

controls or treatment

groups
78

TAXON ENDPOINT TEST

SUBSTANCE MRID STUDY CLASSͲIFICATION COMMENTS

Zebra Finch

(Poephila

guttata)

14Ͳday LD50

>2,250 mg

a.i./kgͲbw

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557764

SupplementalͲ

for qualitative

use only.

Mortality

NOAEL = 2250 mg a.i./kgͲ

bw (the limit dose) no

mortalities were reported

Female WeightͲgain

NOAEL = 2250 mg a.i./kgͲ

bw (the limit dose)

Male WeightͲgain

NOAEL = <2250 mg a.i./kgͲ

bw

Regurgitation had

occurred in some of the

birds; these birds were

removed from the test and

replaced with new birds.

Although frank sublethal

effects were noted in the

study (i.e., reduced male

weight gain), the highest

concentration tested is >

10x the estimated

environmental

concentration (based on

the proposed label: 2

applications at 0.0091 lb

a.i./acre). Therefore, a

definitive LD50 value is not

needed at this time to fully

assess risks to birds

(including federally listed

and nonͲlisted species).

SubͲAcute Dietary

Bobwhite

quail (Colinus

virginianus)

8Ͳday LC50

>4858 mg

a.i./kgͲdiet

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557765 Acceptable

NOAEC = 3350 mg a.i./kg

diet (based on reduced

weight gain); Although

frank sublethal effects

were noted in the study

(i.e., reduced weight gain),

the highest concentration

tested is > 10x the

estimated environmental

concentration (based on

the proposed label: 4

applications at 0.084 lb

a.i./acre, 3Ͳday application

interval). Therefore, a

definitive LD50 value is not
79

TAXON ENDPOINT TEST

SUBSTANCE MRID STUDY CLASSͲIFICATION COMMENTS

needed at this time to fully

assess risks to birds

(including federally listed

and nonͲlisted species).

Mallard duck

(Anas

platyrhynchos)

8Ͳday LC50

>6000 mg

a.i./kgͲdiet

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557766 Acceptable

NOAEC = 3350 mg a.i./kg

diet (based on reduced

weight gain); Although

frank sublethal effects

were noted in the study

(i.e., reduced weight gain),

the highest concentration

tested is > 10x the

estimated environmental

concentration (based on

the proposed label: 2

applications at 0.0091 lb

a.i./acre, 10Ͳday

application interval).

Therefore, a definitive LD50

value is not needed at this

time to fully assess risks to

birds (including federally

listed and nonͲlisted

species).

Chronic

Bobwhite

quail (Colinus

virginianus)

NOAEC = 403

mg a.i./kgͲ

diet

LOAEC = 1040

mg a.i./kgͲ

diet

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557767 Acceptable

The LOAEC was based on a

statistically significant

reduction (9%) in the

number of hatched 3Ͳweek

embryos.

Mallard duck

(Anas

platyrhynchos)

NOAEC =

1040 mg

a.i./kgͲdiet

LOAEC >1040

mg a.i./kgͲ

diet

HalauxifenͲ

methyl

TGAI (97.2% a.i.)

48557768 Acceptable There were no effects

noted in the study.

In all of the avian acute and subͲacute toxicity studies submitted, there were no mortalities at

the highest treatment levels tested (i.e., all of the LD50 and LC50 endpoints are ‘greater than’

values); therefore, these endpoints are not used to calculate RQ values. These endpoints are,

however, used to help characterize risk in the Risk Description section of this assessment.

Frank sublethal effects were noted in the acute oral study with zebra finch (i.e., regurgitation)

as well as in the subͲacute dietary study (i.e., reduced feed consumption and/or reduced weight

gain) using bobwhite quail and mallard ducks. Although frank sublethal effects were noted in

these studies, the highest concentrations tested are > 10x the estimated environmental

concentration (based on the proposed label: 2 applications at 0.0091 lb a.i./acre, 10Ͳday
80

application interval). The ‘10x’ factor is based on the current acute listed species LOC for birds

and mammals (i.e., RQ > 0.1 or 1/10th the acute/subͲacute endpoint value). Therefore, a

definitive LD50 or LC50 value is not needed at this time to fully assess risks to birds (including

federally listed and nonͲlisted species).

Avian reproduction studies were performed for halauxifenͲmethyl in two species, northern

bobwhite quail and mallard duck. The lowest LOAEC was for the bobwhite quail (1040 mg/kgͲ

diet) based on reduced (9% when compared to controls) number of eggs hatched per live

embryo at 3 weeks (MRID 48557768). The lowest NOAEC was also for the bobwhite quail (403

mg a.i./kgͲdiet) (MRID 48557768). There were no statistically significant (ɲ=0.05) effects noted

in the mallard reproduction study (NOAEC = 1040 mg a.i./kgͲdiet) (MRID 48557768). For the

purposes of this risk assessment, 403 mg a.i./kgͲdiet serves as the toxicological endpoint for

evaluating chronic effects in birds (Table 24).

Mammals

Based on the LD50 value for the Norway rat (Rattus norvegicus) of >5,000 mg a.i./kgͲbw,

halauxifenͲmethyl is characterized as “practically nontoxic” to mammalian species on an acute

oralͲexposure basis (MRID 48557815); the study is classified as ‘acceptable’) (see Table 24).

There were no mortalities or sublethal effects noted in the study. In this assessment, an LD50

value of >5,000 mg a.i./kgͲbw will be used to assess the risk of halauxifenͲmethyl to mammals.

The LD50 value for XDEͲ729 acid with the Norway rat (Rattus norvegicus) is also >5,000 mg a.i./kgͲ

bw, and is characterized as “practically nontoxic” to mammalian species on an acute oralͲ

exposure basis (MRID 48557814); the study is classified as ‘acceptable’) (see Table 24).There

was one mortality within two days of administration. In this assessment, an LD50 value of

>5,000 mg a.i./kgͲbw will be used to assess the risk of halauxifenͲacid to mammals.

A 2Ͳgeneration study was performed for XDEͲ729 acid in R. norvegicus. The lowest NOAEL was

103 mg a.i./kg/day based on decreased body weight gains and food consumption during late

gestation/early lactation in females at 443 mg a.i./kg/day (MRID 48557841; this study is

classified as ‘acceptable’). No effects on reproduction or offspring survival were reported. The

NOAEL for reproductive effects was 443 mg a.i./kg/day. For the purposes of this risk

assessment, the parental NOAEL of 103 mg a.i./kg/day serves as the toxicological endpoint for

evaluating chronic effects of halauxifenͲacid in mammals.

Terrestrial Invertebrates

The applicant submitted several terrestrial invertebrate studies on including the honey bee

(Apis mellifera), earthworm (Eisenia fetida), predatory mite (Hypoaspis aculeifer), and

Collembola (Folsomia candida) to evaluate toxicity of halauxifenͲmethyl and the major

degradates on terrestrial invertebrates. The studies using halauxifenͲmethyl resulted in the

following: a honey bee acute contact LD50 of >98.1 μg a.i./bee (MRID 48557890); a honey bee

acute oral LD50 of >108.0 μg a.i./bee (MRID 48557890); and an EC50 of >1,000 mg a.i./kg dry

weight (dw) substrate for earthworms (MRID 48557891).Therefore, halauxifenͲmethyl is
81

classified as ‘practically nontoxic’ to nonͲtarget terrestrial invertebrates on an acute oral and

contact exposure basis. In the acute contact study with honey bees, the NOAEL was 98.1 μg

a.i./bee (the highest concentration tested) and mortality in the study ranged from 0 to 6% in

the different treatment groups. There were no mortalities or sublethal effects noted in the

acute oral bee study, or the earthworm study, therefore the NOAECs are respectively 108 μg

a.i./bee and 1,000 mg a.i./kgͲdw substrate (the highest concentrations tested). A number of

additional studies were provided to PMRA and APVMA, to fulfill registration requirements in

Canada and Australia. These studies were not reviewed by EPA; however, the results indicate

that halauxifenͲmethyl, XDEͲ729 acid, and X11449757 are not toxic to terrestrial invertebrates

(Table 25) at environmentally relevant concentrations (based on the proposed application

rates).

Table 25. Submitted Toxicity Data for HalauxifenͲmethyl and Transformation Products for

Terrestrial Invertebrates

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

Honey bee

(Apis

melifera)

Acute contact

LD50 >98.1 μg

a.i./bee

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557890 Acceptable

NOAEL = 98.1 μg

a.i./bee (the limit dose).

There were nonͲ

significant mortalities

(6%) in the highest test

concentration as

compared to the

control. No other

effects or sublethal

effects were reported.

Honey bee

(Apis

melifera)

Acute oral

LD50 >108.0

μg a.i./bee

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557890 Acceptable

NOAEL = 108.0 μg

a.i./bee (the limit dose).

There were no

mortalities or sublethal

effects reported.

Earthworm

(Eisenia

fetida)

14Ͳday LC50

>1000 mg

a.i./kg soil

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557891 Supplemental

NOEC = 1000 mg a.i/kg

soil (the limit dose).

There were no

mortalities or sublethal

effects reported.

Earthworm

(Eisenia

fetida)

14Ͳday LC50

>1000 mg

a.i./kg soil

XDEͲ729 acid

TGAI (95.3% a.i.) 48557892 Supplemental

NOEC = 500 mg a.i/kg

soil based on a

significant reduction in

bodyweight at 14Ͳdays.

There were no

mortalities reported.

Earthworm

(Eisenia

fetida)

14Ͳday LC50

>1000 mg

a.i./kg soil

X11449757

TGAI (98.6% a.i.) 48557893 Supplemental

NOEC = 1000 mg a.i/kg

soil (the limit dose).

There were no

mortalities or sublethal

effects reported.
82

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

Predatory

mite

(Hypoaspis

aculeifer)

Reproduction

14Ͳday NOEC

= 12.5 mg

a.i./kg dry

substrate

XDEͲ729 acid TGAI

(95.2% a.i.) 49053113 Supplemental

NOEC = 12.5 mg a.i./kg

dry substrate, based on

a 45% reduction in

young produced at the

25 mg a.i./kg dry

substrate test level.

Mortalities ranged from

13Ͳ20% in the

treatment groups but

were determined to be

not statistically different

from the controls.

Predatory

mite

(Hypoaspis

aculeifer)

Reproduction

14Ͳday NOEC

= 25 mg

a.i./kg dry

substrate

X11449757

TGAI (98.6% a.i.) 49053113 Supplemental

NOEC = 25 mg a.i./kg

dry substrate. No

statistically significant

differences between the

control and treatment

groups for mortality or

reproduction effects.

Mortalities ranged from

8Ͳ15% in the treatment

groups but were

determined to be not

statistically different

from the controls.

Collembola

(Folsomia

candida)

Survival and

Reproduction

28Ͳday NOEC

= 1000 mg

a.i./kg dryͲ

soil

HalauxifenͲmethyl

TGAI (97.2% a.i.) 48557877 Supplemental

NOEC = 1000 mg a.i/kg

dryͲsoil (the limit dose).

There were 12Ͳ18%

mortalities reported in

the test concentrations,

however these were not

statistically different

from the controls.

Statistically significant

reductions of young

springtails were

reported at 2.5 and 5.0

mg a.i./kg dryͲsoil,

however these were not

observed in the highest

two test concentrations.

Collembola

(Folsomia

candida)

Survival and

Reproduction

28Ͳday

LC50/EC50

XDEͲ729 acid TGAI

(95.3% a.i.) 49053112 Supplemental

NOEC = 25 mg a.i./kg

dryͲsubstrate.No

reproductive effects

were observed.

Mortalities ranged from

10Ͳ23% in the
83

TAXON ENDPOINT TEST SUBSTANCE MRID STUDY CLASSͲ

IFICATION COMMENTS

> 25 mg

a.i./kg dryͲ

substrate

treatment groups but

were determined to be

not statistically different

from the control.

Collembola

(Folsomia

candida)

Survival and

Reproduction

28Ͳday

LC50/EC50

> 10 mg

a.i./kg dryͲ

soil

X11449757

TGAI (98.6% a.i.) 49053114 Supplemental

NOEC = 10 mg a.i./kg

dryͲsoil.Mortalities

ranged from 12Ͳ24% in

the treatment groups

but were determined to

be not statistically

different from the

control.

A statistically significant

reduction in the number

of offspring was

reported at 5.0 mg

a.i./kg dryͲsoil. This was

determined to not be

treatment related due

to no effects on

reproduction seen at

the highest test

concentration.



Terrestrial Plants

Formulation GFͲ2685 (halauxifenͲmethyl only)

The effects of the proposed halauxifenͲmethyl formulation, GFͲ2685 (10.4% a.i.), was tested on

various monocots and dicots in Tier II seedling emergence and vegetative vigor studies. Results

of the Tier II seedling emergence study showed no measurable effects to the grasses tested at

the maximum test treatment level and slightly below the proposed application rate of 0.0091

lbs a.i./A (Ryegrass, 0.00892 lb a.i./A; oat and corn, 0.0178 lb a.i./acre (MRID 48557769). The

most sensitive monocot tested (the only nonͲgrass species) showed significant decreases in

fresh weight at 0.00223 lb a.i./A; therefore, the NOAEC for onion is 0.00111 lb a.i./A, and the

IC25 is 0.00394 lb a.i./A. Dicots are most impacted by GFͲ2685; the most sensitive species was

carrot based on survival (number of emerged individuals compared to the number of seeds

planted; NOAEC 0.000558 lb a.i./A, IC25 0.00181 lb a.i./A).

Vegetative vigor testing (MRIDs 48557770 and 49574405) indicated that onion was again the

most sensitive monocot (fresh shoot weight IC25 = 0.000128 lb a.i./A); the NOAEC for onion

fresh shoot weight was 0.000139 lb a.i./A which is higher than the IC25 so the IC05 (0.0000122

lbs a.i./A) is used. In this study the grasses, corn, oat and ryegrass all showed signs of toxicity;

the most sensitive grass was ryegrass (IC25= 0.0103 lb a.i./A, NOAEC = 0.00892 lb a.i./A) which is

equal to the proposed single maximum application rate for wheat, barley and triticale (0.0091
84

lb a.i./A). Among broadleaf plants, soybeans were the most sensitive (fresh weight IC25 =

0.0000102 lb a.i./A); the NOAEC for soybean fresh shoot length was 0.00000872 lb a.i./A. Table

26 and Table 27 provide the most sensitive endpoints from all plant species tested with

formulation GFͲ2685. A summary of the endpoints to be used for RQ calculations are provided

in Table 28.

Table 26. Terrestrial Plants Toxicity: Seedling Emergence for GFͲ2685 (lb a.e./A)a

Species Endpoint NOEC IC05 IC25 IC50

Monocots

Onion Fresh weight 0.00111 0.000735 0.00394 0.0127

Corn None 0.0178 NC >0.0178 >0.0178

Oat None 0.0178 NC >0.0178 >0.0178

Ryegrassb Fresh weight 0.00892 NC >0.00892 >0.00892

Dicots

Oilseed Rape None 0.0178 NC >0.0178 >0.0178

Soybean None 0.00892 NC >0.00892 >0.00892

Cucumber None 0.0178 NC >0.0178 >0.0178

Sugar Beet None 0.00892 NC >0.00892 >0.00892

Tomatoc Fresh weight 0.00446 NC NC NC

Carrot Survival 0.000558 0.000453 0.00181 0.00473

a. Exposure is based on lb a.e./A.

b. Inhibitions for ryegrass fluctuated betweenͲ7 and 40% across all test levels in a random manner such that

there was no doseͲresponse relationship.The ICx estimates could not be calculated due to poor model fit

(nonͲlinear).

c. There were statistically significant reductions for tomato of 36 and 55% at the 10 and 20 g a.e./ha treatment

levels, respectively; however, ICx estimates could not be calculated due to poor model fit (Poisson regression)

and because there was no doseͲresponse effect. Inhibitions fluctuated betweenͲ9 and 18% in the lower test

levels.

NCͲnot calculable; value either could not be computed or was not a realistic value. In cases where less than 25%

were observed, the corresponding IC25 value was set as ‘greater than’ the highest concentration tested.

Bolded values identify most sensitive taxon within monocots and dicots.

Data are from MRID 48557769.

Table 27. Terrestrial Plants: Vegetative Vigor Toxicity Data for GFͲ2685a

Species Endpoint NOEC IC05 IC25

Monocots

Onion1 Fresh weight 0.000139 0.0000122 0.000128

Corn1 Fresh weight 0.0178 0.00276 >0.0178

Oat1 None 0.0178 NC >0.0178

Ryegrass1 Fresh weight 0.00892 0.00110 0.0103

Dicots

Oilseed Rape1 Height 0.00223 0.000507 >0.0178

Soybean1 Fresh weight 0.00000872 0.000000683 0.0000102

Cucumber1 Height <0.0000174 0.000000937 0.0000148

Sugar Beet1 Fresh weight 0.00112 0.00157 0.00291

Tomato1 Fresh weight 0.00223 0.00152 0.00517

Carrot1 Fresh weight 0.0000174 0.0000111 0.0000426

Sunflower2 Height <0.00029 0.000117 0.0014
85

a. Exposure is based on lb a.e./A

NCͲnot calculable; value either could not be computed or was not a realistic value. In cases

where less than 25% effects were observed the corresponding IC25 value is represented as

‘greater than’ the highest concentration tested.

Bolded values identify most sensitive taxon within monocots and dicots. 1

Data are from MRID 48557770. 2

Data are from MRID 49574405

Table 28. Summary of the Most Sensitive Endpoints for Formulation GFͲ2685a For RQ

Calculations

Terrestrial Plant

Study Species Endpoint NOEC[IC05] IC25

Seedling Emergence Onion Weight 0.00111

[0.000735] 0.00394

Seedling Emergence Carrot Survival 0.000558

[0.000453] 0.00181

Vegetative Vigor Onion Weight 0.000139

[0.0000122] 0.000128

Vegetative Vigor Soybean Weight 0.00000872

[0.000000683] 0.0000102

a. Exposure is based on lbs a.e./A

Bolded values identify endpoints for RQ calculation

Formulation GFͲ2686 (halauxifenͲmethyl 10.6%, florasulam 10.4%):

A terrestrial plant toxicity vegetative vigor study was submitted to evaluate the toxicity of the

formulation GFͲ2686 to the field bean. This formulation contains both halauxifenͲmethyl and

florasulam (EPA PC Code 129108). Since the submitted study only included one dicot species,

there is uncertainty regarding the relative toxicity across dicots and monocots with this

formulation.The most sensitive field bean endpoint for the vegetative vigor study using GFͲ

2686 (MRID 49574403) is presented in Table 29. The results indicate that formulation GFͲ2686

is more toxic to developing field bean plants than formulation GFͲ2687 on a vegetative vigor

exposure basis.

Table 29. Terrestrial Plants: Vegetative Vigor Toxicity Data For GFͲ2686a

Species Endpoint NOEC IC05 IC25

MonocotsͲNo toxicity data provided by applicant

Dicots

Field Bean Height 0.000017 0.00000039 0.000021

a. Exposure is based on lb a.e./A

Data are from MRID 49574403.
86

Formulation GFͲ2687 (halauxifenͲmethyl 20.9%, florasulam 20%):

Another set of terrestrial plant toxicity studies was submitted to evaluate the toxicity of the

formulation GFͲ2687 to terrestrial plants. This formulation contains both halauxifenͲmethyl and

florasulam (EPA PC Code 129108). The most sensitive endpoints for the seedling emergence

study using GFͲ2687 (MRID 49053302) are presented in Table 30. The results indicate that

formulation GFͲ2687 is more highly toxic to germinating and developing terrestrial plants than

formulation GFͲ2685 on a seedling exposure basis.

Table 30. Terrestrial Plants Toxicity: Seedling Emergence for GFͲ2687 (lb a.e./A)a



Species Endpoint NOEC IC05 IC25 IC50

Monocots

Onion Weight 0.000534 0.000218 0.000767 0.00184

Oat Weight 0.00892 >0.00892 >0.00892 >0.00892

Ryegrass Weight 0.000278 0.00000959 0.00101 >0.00892

Dicots

Field Bean Weight 0.00111 0.000396 0.00132 0.00307

Carrot Weight 0.000556 0.000136 0.000546 0.00143

Cucumber Weight 0.000139 0.0000619 0.000327 0.00105

Oilseed Rape Weight 0.000139 0.000119 0.000413 0.000979

Soybean Height 0.00221 0.000799 0.00507 >0.00892

Sugarbeet Weight 0.000556 0.0000959 0.000573 0.00198

Sunflower Height 0.000133 0.0000317 0.000185 0.000633

Tomato Weight 0.000556 0.0000889 0.000438 0.00133

a. Exposure is based on acid equivalents.

NCͲnot calculable; value either could not be computed or was not a realistic value. In cases where less than

25% were observed, the corresponding IC25 value was set as ‘greater than’ the highest concentration tested.

Bolded values identify most sensitive taxon within monocots and dicots.

Data are from MRID 49053302.

The most sensitive endpoints for the vegetative vigor study using GFͲ2687 (MRIDs 49053302,

and 49574404) are presented in Table 31. In summary, the results indicate that for some taxa

the GFͲ2687 formulation is more highly toxic to terrestrial plants than formulation GFͲ2685;

however, the most sensitive IC25 for both monocots and dicots across these studies are from

the GFͲ2685 study with onion and soybean. Table 32 summarizes the most sensitive endpoints

for formulation GFͲ2687 which will be used to calculate RQs.

Table 31.Terrestrial Plants Toxicity: Vegetative Vigor for GFͲ2687 (lb a.e./A)a



Species Endpoint NOEC IC05 IC25

Monocots

Onion1 Weight 0.00111 0.000238 0.00154

Oat1 Height 0.00221 0.000826 >0.00892

Ryegrass1 Weight 0.00441 0.00153 >0.00892

Dicots

Field Bean1 Height <0.0000173 0.000000288 0.0000123

Carrot1 Weight 0.0000173 0.0000128 0.000104
87

Cucumber1 Height <0.0000173 0.00000643 0.000165

Oilseed Rape1 Weight 0.0000691 0.0000783 0.000429

Soybean1 Height <0.0000691 0.000000470 0.0000201

Soybean2 Height <0.0000087 0.0000000419 0.0000160

Sugarbeet1 Weight 0.000278 0.0000979 0.000899

Sunflower1 Height <0.0000173 0.000000095 0.0000104

Sunflower2 Height 0.0000357 0.000000675 0.000154

Tomato1 Height 0.0000173 0.00000365 0.0000495

a. Exposure is based on lb a.e./A

NCͲnot calculable; value either could not be computed or was not a realistic value. In cases

where less than 25% effects were observed the corresponding IC25 value is represented as

‘greater than’ the highest concentration tested.

Bolded values identify most sensitive taxon within monocots and dicots. 1

Data are from MRID 49053301 2

Data are from MRID 49574404

Table 32. Summary of the Most Sensitive Endpoints for Formulation GFͲ2687 For RQ

Calculations

Terrestrial Plant Study Species Endpoint NOEC

[IC05] IC25

Seedling Emergence Onion Weight 0.000534 [0.000218] 0.000767

Seedling Emergence Sunflower Height 0.000133 [0.0000317] 0.000185

Vegetative Vigor Onion Weight 0.00111 [0.000238] 0.00154

Vegetative Vigor Sunflower Height <0.0000173

[0.000000095] 0.0000104

a. Exposure is based on lb a.e./A

Bolded values identify endpoints for RQ calculation.

Formulation GFͲ2688 (halauxifenͲmethyl 1.6%, fluroxypyr 34.9%):

Toxicity data on this formulation has not been submitted to the Agency, thus conclusive

comparison to the other formulations cannot be made at this time. The applicant has indicated,

on their patent application for this formulation that the combination of halauxifenͲmethyl and

fluroxypyr results in synergistic toxicity. Without toxicity data for this formulation EFED is

unable to evaluate the risk to terrestrial and aquatic plants based on the proposed uses.

HalauxifenͲmethyl Degradate Toxicity to Terrestrial Plants:

Another seedling emergence study was submitted to evaluate the toxicity of the degradate

XDEͲ729 acid to terrestrial plants (MRID 48557882). Table 33 compares the most sensitive EC50s

estimated from the available seedling emergence toxicity data on halauxifenͲmethyl degradates

and formulations. Based on the reviews provided by Health Canada, Pesticide Management

Regulatory Agency (PMRA) and the Australian Pesticides and Veterinary Medicines Authority
88

(AVMPA), only EC50s were calculated. The most sensitive taxon was carrot with an ER50 of

0.000343 lb a.i./A (= 0.384 g a.i./ha). This value is an order of magnitude more sensitive than

the IC50 calculated based on the carrot data for formulation GFͲ2685 (IC50 =0.00473 lb a.i./A

(7.47 g a.i./ha); MRID 48557770) and is similar to that of GFͲ2687. A comparison of the EC50s for

the remaining species indicates that XDEͲ729 acid is at least as toxic as the formulations, and is

at times indicating a higher toxicity. Additional data for the degradate X11449757 (MRID

48557883) reported that effects in the study did not surmount to a 25% reduction in any of the

endpoints for any of the species tested.

Table 33. Terrestrial Plants: Comparison of Submitted Seedling Emergence Toxicity Data for

GFͲ2685, GFͲ2687, XDEͲ729 acid, and X11449757

Species GFͲ2685 GFͲ2687 XDEͲ729 acid X11449757

IC50 IC50 IC50 IC50

Monocots

Onion 0.0127 0.00184 0.00926 >0.0134

Oat >0.0178 >0.0089 >0.0133 >0.0134

Ryegrass >0.00892 >0.0089 >0.0133 >0.0134

Dicots

Oilseed Rape >0.0178 0.00307 >0.0133 >0.0134

Soybean >0.00892 0.00143 0.00836 >0.0134

Field Bean Ͳ 0.00105 0.00764 >0.0134

Cucumber >0.0178 0.000979 0.00818 >0.0134

Sugar Beet >0.00892 >0.00892 0.0120 >0.0134

Tomato NC 0.00198 0.00996 >0.0134

Sunflower Ͳ 0.000633 >0.0133 >0.0134

Carrot 0.00473 0.00133 0.000342 >0.0134

a. Exposure is based on acid equivalents.

Bolded values identify most sensitive taxon within monocots and dicots.

Data are from MRIDs 48557769 (GFͲ2685; halauxifenͲmethyl), 48557882 (XDEͲ729) and 48557883

(X11449757).

F. Risk EstimationͲIntegration of Exposure and Effects Data

Toxicity data and exposure estimates are used to evaluate the potential for adverse ecological

effects on nonͲtarget species. For this assessment of halauxifenͲmethyl, the deterministic risk

quotient method is used to provide a metric of potential risks. Based on toxicity data for XDEͲ

729 acid, X11449757, and X11406790 (see Section III), these residues are expected to be less

toxic than halauxifenͲmethyl to terrestrial and aquatic animals and invertebrates. For aquatic

nonͲvascular plants, halauxifenͲmethyl, XDEͲ729 acid, X11406790, and degradate X11449757

are considered equally toxic. For terrestrial and aquatic vascular plants, halauxifenͲmethyl, XDEͲ

729 acid, and X11406790 are considered equally toxic, and degradate X11449757 is less toxic.

The RQ is a comparison of exposure estimates to toxicity endpoints; estimated exposure

concentrations are divided by acute and chronic toxicity values. The resulting unitless RQs are

compared to the Agency’s levels of concern (LOCs) (see Table 34), which are the Agency’s

interpretive policy such that when LOCs are exceeded, the need for regulatory action may be
89

considered. These criteria are used to indicate when the use of a pesticide, as directed on the

label, has the potential to cause adverse effects on nonͲtarget organisms.

Table 34. Agency Levels of Concern (LOC).

Risk Description RQ Taxa

Acute

Potential for acute risk to nonͲtarget organisms

which may warrant regulatory action in

addition to restricted use classification

acute RQ > 0.5 aquatic animals,

mammals, birds

Acute Restricted

Use

Potential for acute risk to nonͲtarget

organisms, but may be mitigated through

restricted use classification

acute RQ > 0.1 aquatic animals

acute RQ > 0.2 mammals and

birds

Acute Listed

Species

Listed species may be potentially affected by

use

acute RQ > 0.05 aquatic animals

acute RQ > 0.1 mammals and

birds

Chronic

Potential for chronic risk may warrant

regulatory action, listed species may potentially

be affected through chronic exposure

chronic RQ > 1 all animals

NonͲListed and

Listed Plant

Potential for effects in nonͲlisted and listed

plants RQ > 1 all plants

NonͲtarget Aquatic Animals

Based on the available data, halauxifenͲmethyl is classified as moderately toxic to practically

nonͲtoxic for freshwater and estuarine/marine fish, freshwater amphibians, freshwater and

estuarine/marine invertebrates on an acute exposure basis.

There are no exceedances of the acute or chronic LOCs for aquatic animals based on estimated

exposure to halauxifenͲmethyl, XDEͲ729 acid, or a combination of these with X11406790 and

X11449757 (Table 35).

Table 35. Aquatic Animal Risk Quotients for Exposure Estimates Provided in Table 14

Taxonomic Group HalauxifenͲmethyl Halauxifen (XDEͲ729) Total HalauxifenͲmethyl

Residuesa,b

Acute Chronicc Acute Chronicc Acute Chronicc

Freshwater Fish < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.05

Estuarine/Marine

Fish < 0.01 < 0.01 NA NA < 0.01 0.04

Freshwater

Amphibians < 0.01 < 0.01 NA NA < 0.01 0.05

Freshwater

Invertebrates < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.01

Estuarine/Marine

Invertebrates < 0.01 < 0.01 NA NA < 0.01 0.01

a EEC based on estimated concentrations of halauxifenͲmethyl, XDEͲ729 acid, X11406790 andX11449757 b halauxifenͲmethyl toxicity data (the most toxic of the residues) for each taxonomic group was used to

calculate the RQs c Chronic RQs for invertebrates were calculated using the 21Ͳday average concentration from SWCC, and chronic

RQs for fish and amphibians were calculated using the 60Ͳday average concentration.
90

Aquatic Plants

The highest halauxifenͲmethyl peak EEC from the aquatic modeling is 0.00015 mg/L (Table 14).

The RQ for the most sensitive nonͲvascular plant (Skeletonema, EC50 = 1.28 mg a.i./L) is below

the Agency’s LOC (RQ < 1) for risk to listed and nonͲlisted aquatic plants (Table 36). Toxicity

data for the degradates XDEͲ729 acid and X11449757 suggest that these compounds are much

less toxic to aquatic nonͲvascular plants, however, one study on green algae with X11406790

suggests equal toxicity to halauxifenͲmethyl (Pseudokirchneriella, EC50 = 1.83 mg a.i./L, MRID

48557776). Because of this similar toxicity, the estimated peak for total residues, 0.00100 mg

a.i./L (Table 14) were compared to the most sensitive nonͲvascular plant (Skeletonema,

halauxifenͲmethyl EC50 = 1.28 mg a.i./L). The resulting RQ (<0.01) is also below the LOC for nonͲ

vascular aquatic plants.

Aquatic vascular plant RQs are also generated by comparing the peak EEC with the most

sensitive endpoint (Table 36) for halauxifenͲmethyl (Myriophyllum IC50 = 0.000135 mg a.i./L;

IC05 = 0.000008 mg a.i./L). The resulting RQs for halauxifenͲmethyl exposure exceed the nonͲ

listed species as well as the endangered species LOC. The data for XDEͲ729 acid show similar

toxicity (IC50 = 0.00058 mg a.i./L; NOAEC of 0.000185 mg a.i./L) to the methyl and were

compared against the estimated concentration of XDEͲ729 acid (0.00019 mg a.e./L) in the

water. The LOC for listed vascular plants is exceeded while not exceeded for nonͲlisted vascular

plant species. The degradates X11406790 and X11449757 are much less toxic than either

halauxifenͲmethyl or XDEͲ729 acid; therefore, RQs were not calculated for these

transformation products. When unidentified and unextracted residues were included in the

TTR, the LOC exceedance is higher for listed plants and the LOC is exceeded for nonͲlisted

plants. The same statement can be said if the increased persistence of halauxifenͲmethyl and

XDEͲ729 observed in the field studies is considered as the temperature adjustment does not

completely account for the increased persistence observed.

Table 36. Aquatic Plant Risk Quotients for Exposure Estimates Provided in Table 14

NonͲtarget Terrestrial Animals

Birds

HalauxifenͲmethyl and the major degradates are classified as ‘practically nontoxic’ to birds on

an acute and subͲacute exposure basis. Since all of the endpoints from the acute and subͲacute





Aquatic NonͲVascular

Plants Aquatic Vascular Plants

Listed NonͲlisted Listed NonͲlisted

HalauxifenͲmethyl < 0.01 < 0.01 18.75 1.11

Halauxifen (XDEͲ729 acid) < 0.01 < 0.01 1.0 0.3

Bold values denote an exceedance of the LOC.
91

avian toxicity studies are nonͲdefinitive (i.e., the endpoints are ‘greater than’ values), the

endpoints were not used to calculate RQs.

The dietaryͲbased RQs calculated for chronic exposure range from <0.01 to 0.01 using upper

90th percentile Kenaga values. Therefore, none of the avian RQs calculated for chronic exposure

exceed the Agency’s chronic risk LOC of 1.

Mammals

HalauxifenͲmethyl is classified as ‘practically nontoxic’ to mammals on an acute oral exposure

basis. Since the endpoint from the toxicity study is nonͲdefinitive (i.e., it is a ‘greater than’

value), it was not used to calculate RQs.

The dietaryͲbased RQs calculated for chronic exposure from the wheat use (the use with the

highest EECs reported in Table 14 based on two applications of 0.0091 lb a.i./A with a 10Ͳday

reapplication interval). None of the doseͲbased chronic RQs (ч0.01) exceed the Agency’s LOC.

Typically, the Screening Tool for Inhalation Risk (STIR) would be used to determine if there

could be concerns from an inhalation route of exposure; however, the applicant was unable to

conduct an inhalation study. The risk from inhalation is likely not of concern given halauxifenͲ

methyl and XDEͲ729 acid are practically nonͲtoxic to mammals based on an acute oral and

chronic exposure basis.

Terrestrial Invertebrates

HalauxifenͲmethyl is classified as ‘practically nontoxic’ to nonͲtarget terrestrial invertebrates on

an acute exposure basis. ScreeningͲlevel risk assessments do not typically evaluate risks to

terrestrial invertebrates; however, toxicity information for beneficial insects is used to develop

precautionary label language where necessary. Based on the available data, precautionary label

language for bees does not appear necessary. However, a full suite of toxicity data (i.e., acute

and chronic oral exposure to larvae; chronic oral exposure to adult honey bees) are not

available to conduct an assessment for pollinators.

NonͲtarget Terrestrial and SemiͲaquatic Plants

The toxicity studies submitted to evaluate risk to terrestrial plants include two formulations

(one with only halauxifenͲmethyl, and the other coͲformulated with florasulam) and another

with the XDEͲ729 acid degradate.

Formulation GFͲ2685

Ground Application
92

At the maximum single application rate, RQs for listed and nonͲlisted monocots and dicots are

below the LOC for upland areas based on runoff exposure (Table 37). However, the RQs based

on spray drift only, exceed for listed monocots, and listed and nonͲlisted dicots (RQs ranging

from 7.1Ͳ10.0). RQs for nonͲlisted monocots, listed monocots and nonͲlisted dicots in adjacent

semiͲaquatic areas (wetlands) are below the LOCs, however, the RQ for listed dicots in semiͲ

aquatic areas exceed the LOC (RQ = 1.7).

Aerial Application

The RQs for nonͲlisted and listed monocots and dicots in the upland environment are below the

LOC for aerial applications (Table 37). However, there are risks above the LOCs for listed and

nonͲlisted monocots and dicots based on spray drift exposures alone (RQs = 3.4 – 49.9). Listed

monocots and dicots in semiͲaquatic environments also exceed the LOC with RQs ranging from

1.2 to 2.3.

Table 37. Risk Quotients for Plants and Endangered Terrestrial Plants for Ground and Aerial

Application of HalauxifenͲmethyl Formulation GFͲ2685

Organism

Ground Spray Aerial Spray

Adjacent

uplands

Adjacent

wetlands Drift Only Adjacentuplands

Adjacent

wetlands Drift Only

Monocots <0.1 0.2 0.7 0.1 0.3 3.4

Listed

Monocots 0.2 0.9 7.1 0.5 1.2 35.7

Dicots <0.1 0.5 8.5 0.3 0.7 42.6

Listed Dicots 0.3 1.7 10.0 0.9 2.3 49.9

Bold values denote an exceedance of the LOC.

Results presented are based on the maximum seasonal application rate

Spray Drift Distances and LOC exceedances

Following aerial application of formulation GFͲ2685, the distance from the application site

where risk to nonͲlisted terrestrial plants are no longer of concern is 250Ͳ750 feet (depending

on droplet sizes) for monocots and is greater than 2500 ft for dicots (Figure 5). For listed

terrestrial monocots and dicots LOCs are exceeded out beyond 1700 ft for 4 of the tested

species (Figure 6). These distances are reduced when formulation GFͲ2685 is applied by ground

sprays, however, even with ground spray applications the risks to nonͲlisted monocots and

dicots go out to 200 and 800 feet respectively (Figure 7), and the listed species LOCs are

exceeded out beyond 2500 feet for both monocots and dicots for fineͲvery fine droplets and

out to 400Ͳ600 feet for coarse droplet sprays (Figure 8).
93

Figure 5. Tier III AgDrift Aerial Spray Drift Analysis for NonͲlisted Plants: GFͲ2685; the

halauxifen estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial

plants vegetative vigor IC25 endpoints (GFͲ2685 formulation; solid lines). Concentrations exceed

the endpoint to the left of the intersection of the dotted and solid lines.

0.00001

0.0001

0.001

0.01

0.1

0 500 1000 1500 2000 2500

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2685 Aerial Spray Application

Vegetative Vigor IC25

Fine-Medium Droplet

Coarse to Very Coarse Droplet

Corn, Oat, Oilseed Rape

(>0.0178)

Tomato (0.00517)

Sugar Beet (0.00291)

Sunflower (0.0014)

Onion (0.000128)

Carrot (0.0000426)

Cucumber (0.0000148)

Soybean (0.0000102)
94

Figure 6. Tier III AgDrift Aerial Spray Drift Analysis for Listed Plants: GFͲ2685; the halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC05 endpoints (GFͲ2685 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines.

0.000001

0.00001

0.0001

0.001

0.01

0.1

0 500 1000 1500 2000 2500

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2685 Aerial Spray Application

Vegetative Vigor Listed Species (NOAEC or IC05)

Fine-Medium Droplet

Coarse to Very Coarse Droplet

Corn, Oat (0.0178)

Ryegrass (0.00892)

Oilseed Rape, Tomato (0.00223)

Sugar Beet (0.00112)

Sunflower (0.000117)

Onion (0.0000122)

Carrot (0.0000174)

Cucumber (0.0000148)

Soybean (0.00000872)
95

Figure 7. Tier I AgDrift Ground Spray Drift Analysis for NonͲlisted Plants: GFͲ2685; the

halauxifen estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial

plants vegetative vigor NOAC or IC05 endpoints (GFͲ2685 formulation; solid lines).

Concentrations exceed the endpoint to the left of the intersection of the dotted and solid lines.

0.000001

0.00001

0.0001

0.001

0.01

0.1

0 200 400 600 800 1000

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2685 Ground Spray Application

Vegetative Vigor IC25

GF-2685 Coarse to Medium

Coarse, Low Boom

GF-2685 Fine to Very Fine, High

Boom

Corn, Oat, Oilseed Rape

(>0.0178)

Tomato (0.00517)

Sugar Beet (0.00291)

Sunflower (0.0014)

Onion (0.000128)

Carrot (0.0000426)

Cucumber (0.0000148)

Soybean (0.0000102)
96

Figure 8. Tier I AgDrift Ground Spray Drift Analysis for Listed Plants: GFͲ2685; the halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC05 endpoints (GFͲ2685 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines.

Formulation GFͲ2687

Ground Application

At the maximum single application rate, RQs for listed and nonͲlisted monocots and nonͲlisted

dicots are below the LOC for upland areas based on runoff exposure (Table 37). Listed dicot

risks are of concern for the upland areas with RQs exceeding the LOC (RQ = 1.3). The RQs based

on spray drift only, exceed for listed and nonͲlisted dicots (RQs range from 8.4Ͳ915); however,

listed and nonͲlisted monocot RQs are below the LOCs. RQs for listed and nonͲlisted monocots

and dicots in adjacent semiͲaquatic areas (wetlands) exceed the LOCs with RQs ranging from

1.2 to 7.2.

0.000001

0.00001

0.0001

0.001

0.01

0.1

0 200 400 600 800 1000

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2685 Ground Spray Application

Vegetative Vigor Listed Species (NOAEC or IC05)

GF-2685 Coarse to Medium

Coarse, Low Boom

GF-2685 Fine to Very Fine, High

Boom

Corn, Oat (0.0178)

Ryegrass (0.00892)

Oilseed Rape, Tomato (0.00223)

Sugar Beet (0.00112)

Sunflower (0.000117)

Onion (0.0000122)

Carrot (0.0000174)

Cucumber (0.0000148)

Soybean (0.00000872)
97

Aerial Application

Aerial application of formulation GFͲ2687 results in RQs that exceed the LOCs for listed

monocots, and both listed and nonͲlisted dicots in upland areas (RQs range from 1.0 – 3.9,

Table 38). There are risk concerns for listed and nonͲlisted dicots based on spray drift only (RQs

range from 0.1 to 2473.7), monocot RQs are below the LOCs based on drift alone. The RQs for

listed and nonͲlisted monocots and dicots in adjacent semi aquatic areas are also above the

LOCs (RQs ranging from 1.7Ͳ9.8).

Table 38. Risk Quotients for Plants and Endangered Terrestrial Plants for Ground and Aerial

Application of HalauxifenͲmethyl Formulation GFͲ2687.

Organism

Ground Spray Aerial Spray

Adjacent

uplands

Adjacent

wetlands Drift Only Adjacentuplands

Adjacent

wetlands Drift Only

Monocots 0.1 0.7 <0.1 0.4 0.9 0.3

Listed

Monocots 0.2 1.0 <0.1 0.5 1.3 0.4

Dicots 0.5 2.8 4.5 1.5 3.8 22.6

Listed Dicots 0.7 3.9 494.7 2.1 5.3 2473.7

Bold values denote an exceedance of the LOC.

Results presented are based on the maximum seasonal application rate

Spray Drift Distances and LOC exceedances

Following aerial application of Formulation GFͲ2687, the distance from the application site

where risk to nonͲlisted terrestrial plants are no longer of a concern is at the edge of field for

monocots and is 1500 feet to greater than 2500 ft for dicots (depending on droplet sizes; Figure

9). For listed terrestrial dicots LOCs are exceeded out beyond 2500 ft for 5 of the tested species

with fineͲmedium droplets and 4 species with coarseͲvery coarse droplets (Figure 10).These

distances are reduced when Formulation GFͲ2687 is applied by ground sprays, however, even

with ground spray applications the risks to nonͲlisted dicots go out to 200 and 700 feet for

coarse to fine droplets respectively (Figure 11), and the Listed Species LOCs are exceeded out

beyond 2500 feet dicots (Figure 12).
98

Figure 9. Tier III AgDrift Aerial Spray Drift Analysis for NonͲListed Plants: GFͲ2687; The

halauxifen estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial

plants vegetative vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines).

Concentrations exceed the endpoint to the left of the intersection of the dotted and solid lines.

0.000001

0.00001

0.0001

0.001

0.01

0.1

0 500 1000 1500 2000 2500

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2687 Aerial Spray Application

Vegetative Vigor IC25

Fine-Medium Droplet

Coarse to Very Coarse Droplet

Oat, Ryegrass (>0.00892)

Onion (0.00154)

Sugarbeet (0.0008989)

Oilseed Rape (0.000429)

Cucumber (0.000165)

Carrot (0.000104)

Tomato (0.0000495)

Soybean (0.0000160)

Field Bean (0.0000123)

Sunflower (0.0000104)
99

Figure 10. Tier III AgDrift Aerial Spray Drift Analysis for Listed Plants: GFͲ2687; The halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines.

1E-08

0.0000001

0.000001

0.00001

0.0001

0.001

0.01

0.1

0 500 1000 1500 2000 2500

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2687 Aerial Spray Application

Vegetative Vigor Listed Species (NOAEC or IC05)

Fine-Medium Droplet

Coarse to Very Coarse Droplet

Ryegrass (0.00441)

Oat (0.00221)

Onion (0.00111)

Sugarbeet (0.000278)

Oilseed Rape (0.0000691)

Carrot; Tomato (0.0000173)

Cucumber (0.00000643)

Soybean (0.0000000419)

Field Bean (0.000000288)

Sunflower (0.000000095)
100

Figure 11. Tier I AgDrift Ground Spray Drift Analysis for NonͲlisted Plants: GFͲ2687; The

halauxifen estimated deposition curves (dotted lines) overlaid with the nonͲlisted terrestrial

plants vegetative vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines).

Concentrations exceed the endpoint to the left of the intersection of the dotted and solid lines.

0.000001

0.00001

0.0001

0.001

0.01

0.1

0 200 400 600 800 1000

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2687 Ground Spray Application

Vegetative Vigor IC25

GF-2687 Fine to Very Fine, High

Boom

GF-2687 Coarse to Medium

Coarse, Low Boom

Oat, Ryegrass (>0.00892)

Onion (0.00154)

Sugarbeet (0.0008989)

Oilseed Rape (0.000429)

Cucumber (0.000165)

Carrot (0.000104)

Tomato (0.0000495)

Soybean (0.0000160)

Field Bean (0.0000123)

Sunflower (0.0000104)
101

Figure 12. Tier I AgDrift Ground Spray Drift Analysis for Listed Plants: GFͲ2687; The halauxifen

estimated deposition curves (dotted lines) overlaid with the listed terrestrial plants vegetative

vigor NOAC or IC25 endpoints (GFͲ2687 formulation; solid lines). Concentrations exceed the

endpoint to the left of the intersection of the dotted and solid lines.

Terrestrial Plant Communities

No terrestrial plant community studies have been submitted for halauxifen. The available single

species toxicity tests show that the monocot and dicot taxa with definitive IC25 values would

result in LOC exceedances for potentially large areas off of the field primarily due to spray drift

exposure. While halauxifen exposure impacts from spray drift are the primary concern, runoff,

which may lead to reduced fecundity, is also of concern.

Contaminated Irrigation

In addition to the exposure due to runoff and spray drift, halauxifen is considered mobile and

persistent, so groundwater or surface water used for irrigation purposes is an additional route

of exposure for terrestrial and semiͲaquatic plants. To characterize the potential risk, the range

1E-08

0.0000001

0.000001

0.00001

0.0001

0.001

0.01

0.1

0 200 400 600 800 1000

Concentration (lb a.e./A)

Distance (ft) 

Formulations GF-2687 Ground Spray Application

Vegetative Vigor Listed Species (NOAEC or IC05)

GF-2687 Fine to Very Fine, High

Boom

GF-2687 Coarse to Medium

Coarse, Low Boom

Ryegrass (0.00441)

Oat (0.00221)

Onion (0.00111)

Sugarbeet (0.000278)

Oilseed Rape (0.0000691)

Carrot; Tomato (0.0000173)

Cucumber (0.00000643)

Soybean (0.0000000419)

Field Bean (0.000000288)
102

of peak groundwater concentrations generated using PRZMͲGW were used to estimate the

amount of halauxifenͲmethyl that could be applied to an acre, based on the assumption that an

acre inch of groundwater were used for irrigation. Maximum peak groundwater concentrations

for XDEͲ729 acid estimated across the six standard scenarios (0.76 μg/L, respectively) result in

application rates of 0.00017 lb a.e./A (APPENDIX H). The same process was applied to the

potential use of the farm pond as a water source for irrigation, the maximum peak

concentration from SWCC (0.19 μg/L), which resulted in an application rate of 0.00004 lb a.e./A.

Based on the available seedling emergence data, the estimated concentration for the Wisconsin

Corn scenario (maximum peak estimate) is close to but below the IC25 for monocots (0.000767

lb a.e./A); however, these estimates exceed the IC25 for dicots (0.000185 lb a.e./A). Therefore

irrigating an agricultural crop with this groundwater could result in crop damage. The estimated

irrigation application rates exceed the vegetative vigor IC25 for monocots (0.000128 lb a.e./A)

and dicots (0.0000102 lb a.i./A). Estimated application rates from surface water irrigation

estimates using either the peak or the 60Ͳday maximum average, are similar to the maximum

peak estimate for groundwater. Therefore, as with groundwater, there are risks to crops from

irrigation water taken from a contaminated farm pond or a similar surface water body.

Contaminated Compost

Composted plant materials as well as manure are also a concern for residues of halauxifen.

Similar compounds, such as clopyralid (PC Code 117403), triisopropanolamine salt of

aminopyralid (PC Code 005209), and picloram TIPA salt (PC Codes: 005101, 005102, 005104)

have multiple incident reports in the Agency’s Environment Incident Information System (EIIS)

database. These incidents have included reports of damage and crop failure in potatoes,

tomatoes, peas, beans, melons, onions, peppers, carrots, lettuce, roses and landscape gardens

due to the application of manure compost contaminated residues of these chemicals15,16. While

it is currently unclear if similar effects should be expected from halauxifen, given the effects

seen in other members of the chemical class, potential compost carryͲover cannot be ruled out.

It is important to note that the limits of detection and quantification of halauxifenͲmethyl in soil

(0.05 μg/kg17 and 0.02 μg/kg) and water (0.05 μg/L) are not sufficient for identifying the

presence or absence of halauxifenͲmethyl residues of concern at levels equal to the

toxicological endpoints identified in this assessment for plants18. Therefore, it is possible that

15 USEPA. 2009. Ecological Risk Assessment for the Triisopropanolamine Salt of Aminopyralid Section 3 New Uses

on Field Corn and Field Corn grown for Ensilage. 16 USEPA. 2013. Problem Formulation for the Environmental Fate and Ecological Risk, Endangered Species, and

Drinking Water Assessments in support of the registration review of Picloram. 17 LOQ = 0.05 μg/kg = 0.00005 mg/kg; LOD = 0.02 μg/kg

0.00005 mg/kg (s) = [x] kg/ha x 106 mg/kg / [0.15 m (depth) x 104 m2

/ha x 1.5 x 103 kg(s)/m3(density)]

0.00005 mg/kg(s) = [x] kg/ha x 106 mg/kg / 2.25 x 106 kg (s)/ha

= 1.1 x 10Ͳ4 kg/ha = LOQ = 1.0 x 10Ͳ4 lb/A; LOD = 8.6 x 10Ͳ5 lb/A 18 Listed dicot IC05 = 9.5 x 10Ͳ8 lb/A (MRID 49053301) x 0.454 kg/lb / 2.47 ha/A] x 106 mg/kg / [0.15 m (depth) x 104

m2

/ha x 1.5 x 103 kg(s)/m3(density)] = 1.7 x 10Ͳ8 kg/ha x 106 mg/kg / 2.25 x 106 kg (s)/ha = 4.3 x 10Ͳ9 mg/kg = 7.8 x

10Ͳ6 μg/kg (s) (IC05); Listed aquatic vascular plant IC05 8.0 x 10Ͳ6 mg/L; (IC50 = 0.000135mg a.i./L); MRID 48557886
103

effects may occur following the application of halauxifenͲmethyl with no mechanism to link the

effects to exposure to halauxifenͲmethyl.

Analytical Methods

The limits of detection (LOD) and quantification (LOQ) of halauxifenͲmethyl, XDEͲ729 acid, and

X11449757 in soil (0.05 μg/kg and 0.02 μg/kg) and water (0.05 μg/L), while quite low, are not

sufficient for identifying the presence or absence of these residues at levels equal to the

toxicological endpoints identified for several terrestrial plants or aquatic organisms in this

assessment. A recently submitted soil method reports a lower LOD (0.00045 μg/kg) and LOQ

(0.0015 μg/kg) for halauxifenͲmethyl, XDEͲ729 acid in soil; however, no independent laboratory

validation has been provided for this method. As such this method has not been reviewed since

it cannot be confirmed. The reported lower LOD (0.00045 μg/kg) captures all toxicological

endpoints identified in this assessment except for sunflower. Analytical methods for halauxifenͲ

methyl and XDEͲ729 acid in compost (LOD = 0.02 μg/kg; LOQ = 0.05 μg/kg) have been

submitted; however, no independent laboratory validation has been provided, thus, the study

has not been reviewed as it cannot be confirmed. Based on the reported compost LOD, the

method is not sufficient for identifying the presence or absence of these halauxifenͲmethyl and

XDEͲ729 acid at levels equal to the toxicological endpoints for several species included in this

assessment. For example, a summary of the acceptable analytical methods compared to the

toxicity endpoints for GFͲ2685 is provided in Table 39. In addition, analytical methods are not

available for detecting X11406790 in soil or degradates 1, 2, 4, 10, 11, and 14 in soil and water.

These residues cannot be ruled out as residues of concern for terrestrial plants.

Table 39. Analytical Method Comparison with Toxicity Endpoints for Formulation GFͲ2685.

MEASURE OF EFFECT Exposure Pathway

Terrestrial

Plants

Species

Toxicity

Endpoint

Soil Water

Emergence, Transplant

lb a.e./A

Application, Spray Drift,

Irrigation, Compost Irrigation, Runoff

Current Accepted Method Detection Limit

NonͲlisted (Seedling Emergence)

Monocot: 

Allium cepa

Onion

IC25 = 3.94 x 10Ͳ3

Reduced

Fresh

Weight

LOQ 1.0 x 10Ͳ4 lb a.e./A

(0.05 μg/kg)

LOD 8.6 x 10 Ͳ5 lb a.e./A

(0.02 μg/kg)

LOQ 1.3 x 10Ͳ5 lb a.e./A

(0.05 μg/L)

LOD 3.4 x 10Ͳ6 lb a.e./A

(0.015μg/L)

Dicot:

Daucus carota

Carrot

IC25 = 1.81 x 10Ͳ3 Survival

Listed (Seedling Emergence)

Monocot: 

Allium cepa

Onion

NOAEC = 1.11x 10Ͳ3

Reduced

Fresh

Weight

LOQ 1.0 x 10Ͳ4 lb a.e./A

(0.05 μg/kg)

LOD 8.6 x 10 Ͳ5 lb a.e/A

(0.02 μg/kg)

LOQ 1.3 x 10Ͳ5 lb a.e./A

(0.05 μg/L)

LOD 3.4 x 10Ͳ6 lb a.e./A

(0.015μg/L)

Dicot:

Daucus carota

Carrot

NOAEC = 5.58x 10Ͳ4 Survival

NonͲlisted (Vegetative vigor)

Monocot: 

Allium cepa IC25 = 1.28x 10Ͳ4 LOQ 1.0 x 10Ͳ4 lb a.e./A LOQ 1.3 x 10Ͳ5 lb a.e./A
104

MEASURE OF EFFECT Exposure Pathway

Terrestrial

Plants

Species

Toxicity

Endpoint

Soil Water

Emergence, Transplant

lb a.e./A

Application, Spray Drift,

Irrigation, Compost Irrigation, Runoff

Current Accepted Method Detection Limit

Onion Reduced

Fresh

Weight

(0.05 μg/kg)

LOD 8.6 x 10 Ͳ5 lb a.e./A

(0.02 μg/kg)

(0.05 μg/L)

LOD 3.4 x 10Ͳ6 lb a.e./A

(0.015μg/L)

Dicot:

Glycine max

Soybean

IC25 = 1.02x 10Ͳ5

Listed (Vegetative vigor)

Monocot: 

Allium cepa

Onion

IC05 = 1.22x 10Ͳ5

Reduced

Fresh

Weight

LOQ 1.0 x 10Ͳ4 lb a.e./A

(0.05 μg/kg)

LOD 8.6 x 10 Ͳ5 lb a.e./A

(0.02 μg/kg)

LOQ 1.3 x 10Ͳ5 lb a.e./A

(0.05 μg/L)

LOD 3.4 x 10Ͳ6 lb a.e./A

(0.015μg/L)

Dicot:

Glycine

max

Soybean

NOAEC = 8.72x 10Ͳ6

G. Risk Conclusions

The results of this risk assessment indicate that the proposed use of halauxifenͲmethyl is not

likely to result in risk to nonͲtarget terrestrial animals, including insects, birds, reptiles,

terrestrialͲphase amphibians, and mammals. In addition, risk to aquatic animals including

amphibians, fish, invertebrates and aquatic nonͲvascular plants are also not expected.

However, the proposed use of halauxifenͲmethyl may pose a risk to terrestrial, aquatic and

semiͲaquatic vascular plants. This includes agricultural crops grown near the application site,

except for other grain crops. Spray drift is the primary driver for potential riskͲestimated

distances from the application site where risk to nontarget terrestrial plants are no longer of

concern is estimated to be greater than 2500 feet (aerial applications) for more sensitive plants

(e.g., tested plants include sunflower and soybean), including nonlisted and listed species.

Droplet size greatly influences the predicted distances from the application site at which plant

exposure to drift residues would no longer be of concern. There is noted variability in sensitivity

across the tested species: based on aerial applications of fineͲtoͲmedium droplets, drift

distances of <50 feet are predicted for some plants (e.g., corn, oat), whereas drift distances of

~240 to >2500 feet are predicted for other crops (e.g., onion, carrot, cucumber, and soybean).

Risk to plants from application of contaminated irrigation water or compost cannot be

precluded. Based on the limits of detection and quantification of halauxifenͲmethyl in soil (0.05

μg/kg and 0.02 μg/kg) and water (0.05 μg/L), while quite low, these are levels are not sufficient

for identifying the presence or absence of halauxifenͲmethyl at levels equal to the toxicological

endpoints identified in this assessment. Therefore, it is possible that effects could occur

following the application of halauxifenͲmethyl without being able to detect the presence of the

chemical or its degradates.
105

IV. REFERENCES

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger.1994.Literature review and evaluation of the

EPA foodͲchain (Kenaga) nomogram, an instrument for estimating pesticide residues on plants.

Environ. Tox. Chem. 13:1383Ͳ1391.

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. 9Ͳ28.

Taiz, L. and E. Zeiger. 2002.Plant Physiology, Third Edition. Sinauer Associates, Inc.

Thill, D. 2002.Growth regulator herbicides.In Herbicide Action.Purdue University, West

Lafayette, IN.

U.S. EPA, et. al. 2014. Guidance to Assessing Pesticide Risks to Bees. U.S. Environmental

Protection Agency, Health Canada Pesticide Management Regulatory Agency, and California

Department of Pesticide Regulation. June 23, 2014.
106

APPENDIX A. Studies Used in this Risk Assessment

Table A.1. Environmental Fate and Transport Studies

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

Hydrolysis 835.2010 48557729 Acceptable

Aqueous

Photolysis 835.2240 48557731 Supplemental

Several HPLC peaks believed to be polar

compounds were found in the irradiated pH 7

buffer and natural water samples at >10% of

the applied; no attempts were made to

identify these compounds.

Soil Photolysis 835.2410 48557734 Supplemental

Aerobic Soil

Metabolism 835.4100 48557735 Supplemental

Per treatment type, only single samples were

collected at each sampling interval.

The extraction methods are not considered

exhaustive. Unextracted residues were

detected atш10% of the applied and were not

characterized.

Sample results where recoveries were <88% or

>110% of the applied were omitted from the

study report.

Anaerobic Soil

Metabolism 835.4200 48557736 Supplemental

The extraction methods are not considered

exhaustive and unextracted residues detected

atш10% of the applied were not characterized.

Aerobic Aquatic

Metabolism 835.4300 48557738 supplemental

The extraction methods are not considered

exhaustive and unextracted [

14C] residues

were detected atш10% of the applied.

Anaerobic

Aquatic

Metabolism

834.4400 117501 Supplemental

Per treatment type, only single samples were

collected at each sampling interval. For the

clay loam sediment system, the sampling

intervals were inadequate to accurately

calculate a dissipation halfͲlife for parent

halauxifenͲmethyl.

Terrestrial Field

Dissipation

835.6100 49022101 Supplemental

The stability of halauxifenͲmethyl and its

transformation products in frozen soil and

wheat was not adequately determined. The

analytical method was not appropriate for the

detection of the transformation product

X11449757 in soils from four of the test sites

(Sites 3 to 6). The halfͲlife values determined in

this study are not consistent with those

determined under laboratory conditions.

Method

Validation

850.6100

48557862

Acceptable

The method is scientifically valid; however, the

LOD and LOQ for halauxifenͲmethyl and its

products X11393729 and X11449757 in soil is

higher than the lowest toxicological level of

concern for plants. Therefore, effects to plants

may occur at concentrations less than what is

detectable in the environment. No method in

soil is available for X11406790.

48557785
107

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

48557787

Acceptable

The method is scientifically valid; however, the

LOD and LOQ for halauxifenͲmethyl and its

products X11393729 and X11449757 in water

is higher than the lowest toxicological level of

concern for plants. Therefore, effects to plants

may occur at concentrations less than what is

detectable in the environment. No method in

soil is available for X11406790.

48557788

49702101 Acceptable

This is an environmental chemistry method

study that establishes a LOD/LOQ for

halauxifenͲmethyl and halauxifen acid in soil.

The established LOD/LOQ is not less than the

lowest toxicological level of concern. No

independent laboratory validation is available

for this method.

4967103 Acceptable

This is an environmental chemistry method

that establishes LOQ/LOD for halauxifenͲ

methyl and halauxifen acid in compost. The

established LOQ/LOD is not less than the

lowest toxicological level of concern. No

independent laboratory validation is available

for this method.

Batch

Equilibrium 835.1230 48557728 Supplemental

The soils were sterilized via gamma irradiation

prior to use, and it was not established that

the foreign soils used in this study were

comparable to soils that would be found at the

intended use sites in the United States.

Bioconcentration 850.1730 48557760 Acceptable

Compost NonͲGuideline

4967101 Upgradable

This is a decline kinetic experiment conducted

in compost. This study is upgradable to

supplemental following submission of raw data

for individual sample replicates and spiked

transport and storage stability data.

49637102 Upgradable

This is a bioassay (vegetable vigor) study

conducted using compost as a growth media.

This study is upgradable to supplemental

following submission of raw data of the

individual replicates. There are several study

deficiencies confound the interpretation of the

results of this study.

20150714 NA

This is a response memo that provided

additional information to support MRID

4967102.

49702102 Supplemental

This is a bioassay (vegetable vigor) study

conducted using compost as a topͲdressing.

Spike transport and storage stability data are

desired. 1

OPPIN Classifications: Acceptable/Guideline; Acceptable/NonͲGuideline; Cited; Confirmatory; Decision Deferred; Extraneous

submission; In Review; No Decision; Partially Acceptable; Supplemental: Unacceptable/Guideline; Unacceptable/NonͲ

Guideline; Upgradeable.
108

Table A.2. Environmental Effects Studies

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

Acute toxicity for

Daphnia 850.1010 48557744 Acceptable 

Acute toxicity for

Daphnia 850.1010 48557743 Acceptable 

Acute toxicity for

Daphnia 850.1010 48557742 Acceptable 

Acute toxicity for

Daphnia 850.1010 48557741 Acceptable 

Acute toxicity for

Eastern oyster

(Crassostrea

virginica)

850.1025 48557745 Supplemental

Ͳqualitative use only

The study was classified as supplemental

because the study began only after 3 days of

oyster acclimation (recommended 15 days),

and a biologically significant stimulatory

solvent effect (19% increase compared to the

negative control) had been detected and likely

muted the toxic effect of the test material.

Acute toxicity for

Mysid

(Americamysis

bahia)

850.1035 48557746 Supplemental

Ͳqualitative use only

The study was classified as supplemental due

to a nonͲdefinitive endpoint and uncertainty

surrounding the value of a definitive endpoint

(mortality was 40% at the highest test

concentration (limit of solubility in the test

medium).

Acute toxicity

Rainbow trout

(Oncorhynchus

mykiss)

850.1075 48557752 Acceptable 

Acute toxicity

Rainbow trout

(Oncorhynchus

mykiss)

850.1075 48557751 Acceptable 

Acute toxicity

Rainbow trout

(Oncorhynchus

mykiss)

850.1075 48557750 Acceptable 

Sheepshead

Minnow,

(Cyprinodon

variegatus)

850.1075 48557749 Acceptable 

Warm water fish

species 850.1075 48557748 Acceptable 

Rainbow trout

(Oncorhynchus

mykiss)

850.1075 48557747 Acceptable 

Chronic toxicity

in Daphnia

magna

850.1300 48557754 Acceptable 

Chronic toxicity

in Daphnia

magna

850.1300 48557753 Acceptable 
109

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

Chronic toxicity

for Mysid

(Americamysis

bahia)

850.1350 48557755 Acceptable 

Fish early life

stage toxicity

test (sheepshead

minnow)

850.1400 48557759 Acceptable 

Fish early life

stage toxicity

test Fathead

minnow

(Pimephales

promelas)

850.1400 48557758 Acceptable 

Fish early life

stage toxicity

test Fathead

minnow

(Pimephales

promelas)

850.1400 48557757 Acceptable 

Fish early life

stage toxicity

test Fathead

minnow

(Pimephales

promelas)

850.1400 48557756 Acceptable 

10Ͳday Midge

Larval

(Chironomus

dilutus)

850.1735 48557761 Acceptable 

28Ͳday Midge

Larval

(Chironomus

dilutus)

850.1735 48557885 Acceptable 

10Ͳday Marine

Amphipod

(Leptocheirus

plumulosus).

850.1740 48557762 Acceptable 

Acute oral

toxicity to Zebra

Finch (Poephila

guttata)

850.2100 48557764 SupplementalͲfor

qualitative use only.

Classified Supplemental because regurgitation

had occurred in some of the birds; these birds

were removed from the test and replaced with

new birds.

Acute oral

toxicity to

Bobwhite quail

(Colinus

virginianus)

850.2100 48557763 Acceptable 

Avian dietary

toxicity (5Ͳday)Ͳ 850.2200 48557766 Acceptable 
110

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

Mallard duck

(Anas

platyrhynchos)

Avian dietary

toxicity (5Ͳday)Ͳ

Bobwhite quail

(Colinus

virginianus)

850.2200 48557765 Acceptable 

Subchronic and

reproductive

toxicity to birdsͲ

Mallard duck

(Anas

platyrhynchos)

850.2300 48557768 Acceptable 

Subchronic and

reproductive

toxicity to birdsͲ

Bobwhite quail

(Colinus

virginianus)

850.2300 48557767 Acceptable 

Acute contact

and Acute Oral

toxicity

Honey bee (Apis

melifera)

850.3020 48557890 Acceptable 

Acute

Earthworm

(Eisenia fetida)

OECD Guideline

222 48557891 Supplemental

Ͳquantitative

This study is not a U.S. EPA guideline, and thus

is classified as supplemental.The study is

scientifically sound.

Acute

Earthworm

(Eisenia fetida)

OECD Guideline

222 48557892 Supplemental

Ͳquantitative

This study is not a U.S. EPA guideline, and thus

is classified as supplemental.The study is

scientifically sound.

Acute

Earthworm

(Eisenia fetida)

OECD Guideline

222 48557893 Supplemental

Ͳquantitative

This study is not a U.S. EPA guideline, and thus

is classified as supplemental.The study is

scientifically sound.

Predatory mite

(Hypoaspis

aculeifer)

OECD Guideline

226 49053113 SupplementalͲquantitative

This study is not a U.S. EPA guideline, and thus

is classified as supplemental.The study is

scientifically sound.

Collembola

(Folsomia

candida)

OECD Guideline

232 48557877 Supplemental

Ͳquantitative

This study is not a U.S. EPA guideline, and thus

is classified as supplemental.The study is

scientifically sound.

Collembola

(Folsomia

candida)

OECD Guideline

232 49053112 Supplemental

Ͳquantitative

This study is not a U.S. EPA guideline, and thus

is classified as supplemental.The study is

scientifically sound.

Collembola

(Folsomia

candida)

OECD Guideline

232 49053114 Supplemental

Ͳquantitative

This study is not a U.S. EPA guideline, and thus

is classified as supplemental.The study is

scientifically sound.

Effects on

terrestrial

vascular plants

850.4100 48557769 Acceptable 
111

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

Effects on

terrestrial

vascular plants

850.4150 48557770 Acceptable 

Effects on

terrestrial

vascular plants

850.4100 49053302 Acceptable 

Effects on

terrestrial

vascular plants

850.4150 49053301 Acceptable 

Effects on

terrestrial

vascular plants

850.4100 48557882 Acceptable 

Effects on

terrestrial

vascular plants

850.4150 48557883 Acceptable 

Effects on

Eurasian

watermilfoil

(Myriophyllum

spicatum)

OECD Draft

Guideline 48557886 Supplemental

The test was performed based on the draft

AMRAP Method (MALTBY et al.

2010): Growth Inhibition Test for the Rooted

Aquatic Macrophyte, Myriophyllum sp.,

submitted to OECD for evaluation, 2011.

Effects on

Eurasian

watermilfoil

(Myriophyllum

spicatum)

OECD Draft

Guideline 48557887 Supplemental

The test was performed based on the draft

AMRAP Method (MALTBY et al.

2010): Growth Inhibition Test for the Rooted

Aquatic Macrophyte, Myriophyllum sp.,

submitted to OECD for evaluation, 2011.

Effects on

Eurasian

watermilfoil

(Myriophyllum

spicatum)

OECD Draft

Guideline 48557888 Supplemental

The test was performed based on the draft

AMRAP Method (MALTBY et al.

2010): Growth Inhibition Test for the Rooted

Aquatic Macrophyte, Myriophyllum sp.,

submitted to OECD for evaluation, 2011.

Effects on

Eurasian

watermilfoil

(Myriophyllum

spicatum)

OECD Draft

Guideline 48557889 Supplemental

The test was performed based on the draft

AMRAP Method (MALTBY et al.

2010): Growth Inhibition Test for the Rooted

Aquatic Macrophyte, Myriophyllum sp.,

submitted to OECD for evaluation, 2011.

Effects on lemna 850.4400 48557774 Acceptable

Effects on lemna 850.4400 48557773 Acceptable

Effects on lemna 850.4400 48557772 Acceptable

Effects on lemna 850.4400 48557771 Acceptable

Acute toxicity to

algaeͲsaltwater

diatom

(Skeletonema)

850.4500 48557784 Supplemental

–quantitative

The control and treatments were only

replicated 3 times.A minimum of 4 replicates

per level is needed.Three replicates are

sufficient to satisfy the OECD 201 guideline.

After 96 hours, the mean cell density of the

negative control increased by a factor of 26.

An increase by a factor of at least 30 is needed

for a S. costatum test to be considered valid.

The initial cell density was 7.7x104 cells/mL.
112

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

An initial cell density of 1.0x104 cells/mL is

recommended for S. costatum.

Acute toxicity to

algaeͲbluegreen

(Anabaena)

850.4500 48557783 Acceptable 

Acute toxicity to

algaeͲ

freshwater

diatom

(Navicula)

850.4500 48557782 Acceptable 

Acute toxicity to

algaeͲ

freshwater green

(Pseudokirchneri

ella)

850.4500 48557781 Acceptable 

Acute toxicity to

algaeͲspecies to

be determined

850.4500 48557780 Acceptable 

Acute toxicity to

algaeͲsaltwater

diatom

(Skeletonema)

850.4500 48557779 Acceptable 

Acute toxicity to

algaeͲbluegreen

(Anabaena)

850.4500 48557778 Acceptable 

Acute toxicity to

algaeͲ

freshwater

diatom

(Navicula)

850.4500 48557777 Acceptable 

Acute toxicity to

algaeͲ

freshwater green

(Pseudokirchneri

ella)

850.4500 48557776 Acceptable 

Acute toxicity to

algaeͲ

freshwater green

(Pseudokirchneri

ella)

850.4500 48557775 Acceptable 

Acute Juvenile

Amphibian

Toxicity

Non Guideline 48557884 Acceptable 

Frog

metamorphosis

(AMA)

890.1100 48557866 Supplemental –

qualitative

This study was classified as supplemental due

to significant solvent effects and control

mortality.

Fish short term

reproduction 890.1350 48557867 Acceptable 
113

Data

Requirement

Guideline

Number MRID Study Classification1 Remarks

assay Fathead

minnow

(Pimephales

promelas)

Fish short term

reproduction

assay Fathead

minnow

(Pimephales

promelas)

890.1350 48557868 Supplemental

Ͳquantitative

Since there were no apparent treatmentͲ

related effects of halauxifen on reproduction,

the samples collected for gonad

histophathology and serum vitellogenin (Vtg)

were not processed.

 
*Pages 114-116 Have Been Removed*
117

APPENDIX C. Kinetic Analysis

HalauxifenͲmethyl

Hydrolysis

Aquatic Photolysis

Irradiated Test System
118

Dark Control

Soil Photolysis

Irradiated Test System

Hydrolysis of halauxifen methyl at pH 7, 25°C

Days% AR

0

 1

 1

 3

 3

 7

 7

 10

 10

 14

 14

0

 1

 1

 3

 3

 7

 7

 10

 10

 14

 14

100.

97.1

98.1

97.3

96.5

95.5

96.2

93.7

93.9

92.6

92.8

97.7

97.1

97.9

98.1

97.6

95.8

95.9

94.1

93.3

91.9

93.6

0 2 4 6 8 10 12 14

0

20

40

60

80

100

Time

Concentration

SFO

DFOP

IORE

-1.5

-1

-0.5

0

0.5

1

1.5

-1.5

-1

-0.5

0

0.5

1

1.5

-1.5

-1

-0.5

0

0.5

1

1.5

0 2 4 6 8 10 12 14

DT50 DT90 F

2 C0 Parameters

SFO 158 526 0.31 98.4 k 0.00438

DFOP 352 2184 0.38 98.5 f 0.326k0 0.0122k1 0.000874

IORE 913 1141561 0.34 98.5 N 5.4k 8.44e-12

SC

SSFO

Slowt1 2

tRIORE

11.3

9.82

 793

3.44e+05
119

Dark Control

Aerobic Soil Metabolism

Halauxifen-methyl (XDE-729 methyl) in Clay Loam Soil

DaysHalauxifen-methyl

0

0

 1

 1

 3

 3

 7

 7

 14

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 104

 120

 153

 153

98.1

97.2

69.1

70.6

37.0

40.6

19.8

22.3

12.6

12.1

4.70

5.40

5.20

5.30

3.80

3.70

2.50

3.20

2.80

2.40

2.80

2.00

2.00

0 50 100 150

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 50 100 150

DT50 DT90 F

2 C0 Parameters

SFO 2.76 9.16 17 93.8 k 0.251

DFOP 2.22 22.1 5.3 97.4 f 0.819k0 0.411k1 0.0269

IORE 2.13 17.5 4.7 98.5 N 1.92k 0.00659

SC

SSFO

Slowt1 2

tRIORE

55.4

 528

25.8

5.27
120

Halauxifen-methyl (XDE-729 methyl) in Silt Loam Soil

DaysHalauxifen-methyl

0

0

 1

 1

 3

 3

 7

 7

 14

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 104

 120

 120

 153

 153

94.7

94.7

58.9

51.3

25.0

20.9

7.90

7.30

4.80

4.20

1.70

1.80

1.60

1.70

1.30

1.40

0.900

1.10

1.00

1.10

1.10

1.00

0.900

1.00

0 50 100 150

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

0 50 100 150

DT50 DT90 F

2 C0 Parameters

SFO 1.45 4.81 11 93.4 k 0.479

DFOP 1.34 5.7 3.6 94.4 f 0.92k0 0.58k1 0.034

IORE 1.27 6.52 5.6 95 N 1.48k 0.0717

SC

SSFO

Slowt1 2

tRIORE

72.6

 157

20.4

1.96

Halauxifen-methyl (XDE-729 methyl) in Loam Soil

DaysHalauxifen-methyl

0

0

 1

 1

 3

 3

 7

 7

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 104

 120

 120

 153

 153

97.8

96.4

63.2

60.4

23.7

19.8

8.00

6.40

3.80

1.90

1.50

1.60

0.900

1.10

0.800

0.500

0.700

0.700

0.700

0.700

0.600

0.800

0.600

0 50 100 150

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-4

-2

0

2

4

-4

-2

0

2

4

-4

-2

0

2

4

0 50 100 150

DT50 DT90 F

2 C0 Parameters

SFO 1.48 4.91 8.5 97.3 k 0.469

DFOP 1.42 5.32 4.8 97.8 f 0.956k0 0.518k1 0.0233

IORE 1.43 5.35 8 97.8 N 1.15k 0.262

SC

SSFO

Slowt1 2

tRIORE

76.5

77.5

29.7

1.61
121

Anaerobic Soil Metabolism

Halauxifen-methyl (XDE-729 methyl) in Sandy Loam Soil

DaysHalauxifen-methyl

0

0

 1

 1

 3

 3

 7

 7

 14

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 120

 120

98.5

97.1

55.1

48.2

13.8

13.1

4.60

5.00

2.70

3.20

1.40

1.70

1.30

1.50

1.00

1.50

0.800

1.00

0.600

0.900

1.10

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-4

-2

0

2

4

-4

-2

0

2

4

-4

-2

0

2

4

0 204060 80 120

DT50 DT90 F

2 C0 Parameters

SFO 1.08 3.59 8 97.8 k 0.641

DFOP 1.05 3.82 3.7 98.1 f 0.966k0 0.695k1 0.0164

IORE 1.04 3.91 8 98.1 N 1.14k 0.36

SC

SSFO

Slowt1 2

tRIORE

 92

87.4

42.3

1.18

Halauxifen-methyl (XDE-729 methyl) in Clay Loam Soil

DAF Halauxifen-methyl

0

0

 2

 2

 6

 6

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

42.4

52.1

29.3

28.7

11.6

13.4

8.00

8.70

3.40

3.50

3.20

3.30

2.30

2.20

1.30

1.40

1.00

2.00

0 20 40 60 80 100 120

0

10

20

30

40

50

Time

Concentration

SFO

DFOP

IORE

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

0 204060 80 120

DT50 DT90 F

2 C0 Parameters

SFO 3.48 11.6 18 45.9 k 0.199

DFOP 2.83 29.7 5.6 47.4 f 0.815k0 0.325k1 0.0208

IORE 2.75 23.6 7.1 47.5 N 1.96k 0.00881

SC

SSFO

Slowt1 2

tRIORE

79.3

 186

33.3

 7.1
122

Halauxifen-methyl (XDE-729 methyl) in Silt Loam Soil

DAF Halauxifen-methyl

0

0

 2

 2

 6

 6

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

66.6

25.3

10.6

9.40

3.40

3.00

2.40

2.30

0.900

1.00

0.700

0.600

0.600

0.600

0.400

0.500

0.400

0.300

0 20 40 60 80 100 120

0

10

20

30

40

50

60

Time

Concentration

SFO

DFOP

IORE

-20

-10

0

10

20

-20

-10

0

10

20

-20

-10

0

10

20

0 204060 80 120

DT50 DT90 F

2 C0 Parameters

SFO 0.935 3.11 14 45.9 k 0.742

DFOP 0.935 3.1 16 45.9 f 1.55k0 0.741k1 0.74

IORE 0.53 5.01 3.8 46 N 2.04k 0.0354

SC

SSFO

Slowt1 2

tRIORE

 997

 883

0.937

1.51

Halauxifen-methyl (XDE-729 methyl) in Loam Soil

DAF Halauxifen-methyl

0

0

 2

 2

 6

 6

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

26.4

23.6

10.3

9.20

3.50

3.40

2.00

1.80

0.500

0.700

3.00

0.500

0.400

0.300

0.200

0.200

0.600

0.200

0 20 40 60 80 100 120

0

5

10

15

20

25

Time

Concentration

SFO

DFOP

IORE

-3

-2

-1

0

1

2

3

-3

-2

-1

0

1

2

3

-3

-2

-1

0

1

2

3

0 204060 80 120

DT50 DT90 F

2 C0 Parameters

SFO 1.65 5.47 18 24.7 k 0.421

DFOP 1.45 8.17 7.3 25 f 0.89k0 0.563k1 0.0237

IORE 1.23 10.3 8.2 25 N 1.93k 0.0393

SC

SSFO

Slowt1 2

tRIORE

13.6

28.1

29.3

3.09
123

Aerobic Aquatic Metabolism

Halauxifen-methyl (XDE-729 methyl) in Sandy Loam Soil

DAF Halauxifen-methyl

0

0

 2

 2

 6

 6

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

20.2

17.8

9.10

7.30

3.10

3.30

2.00

2.20

0.900

0.700

0.800

0.700

0.600

0.700

0.500

0.400

0.500

0.400

0 20 40 60 80 100 120

0

5

10

15

20

Time

Concentration

SFO

DFOP

IORE

-2

-1

0

1

2

-2

-1

0

1

2

-2

-1

0

1

2

0 204060 80 120

DT50 DT90 F

2 C0 Parameters

SFO 1.93 6.42 19 18.7 k 0.358

DFOP 1.63 15 5.3 19 f 0.85k0 0.534k1 0.0274

IORE 1.43 13.5 5.3 19 N 2.04k 0.0331

SC

SSFO

Slowt1 2

tRIORE

6.63

20.5

25.3

4.07

Halauxifen-methyl (XDE-729 methyl) in Loamy Sand System

Days Halauxifen-methyl

0

0

 2

 2

 5

 5

 8

 8

 14

 14

 22

 22

 30

 30

 43

 43

 62

 62

 79

 79

 103

 103

89.7

85.4

75.3

79.9

28.1

34.5

24.9

64.0

8.20

5.50

0.800

1.40

0.700

1.10

1.20

1.30

0.900

0.400

1.30

0.600

0.300

0.400

0 20 40 60 80 100

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-30

-20

-10

0

10

20

30

-30

-20

-10

0

10

20

30

-30

-20

-10

0

10

20

30

0 20 40 60 80100

DT50 DT90 F

2 C0 Parameters

SFO 5.01 16.6 25 90.8 k 0.138

DFOP 5.01 16.6 27 90.8 f 0.967k0 0.138k1 0.138

IORE 5.15 16.1 26 90.3 N 0.926k 0.183

SC

SSFO

Slowt1 2

tRIORE

2.13e+03

1.9e+03

5.01

4.86
124

Anaerobic Aquatic Metabolism

Halauxifen-methyl (XDE-729 methyl) in Silt Loam System

DaysHalauxifen-methyl

0

0

 2

 2

 5

 5

 8

 8

 14

 14

 22

 22

 30

 30

 43

 43

 62

 62

 79

 79

 103

 103

93.0

94.7

20.3

18.8

1.90

2.70

0.600

1.40

0.700

0.300

0.500

0.400

0.500

0.300

0.100

0.300

0.700

0.300

0.200

0.700

0.100

0.300

0 20 40 60 80 100

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-1

-0.5

0

0.5

1

-1

-0.5

0

0.5

1

-1

-0.5

0

0.5

1

0 20 40 60 80100

DT50 DT90 F

2 C0 Parameters

SFO 0.888 2.95 3.2 93.8 k 0.781

DFOP 0.878 2.97 1 93.8 f 0.993k0 0.797k1 0.00941

IORE 0.85 3.03 2.9 93.9 N 1.09k 0.57

SC

SSFO

Slowt1 2

tRIORE

7.39

7.56

73.7

0.911

Halauxifen-methyl in Clay Loam System

DaysHalauxifen-methyl

0

0

 1

 1

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 44

 44

105.

94.9

28.0

27.6

1.20

1.30

0.500

10.2

0.300

0.400

0.200

0.300

0.200

0.200

1.00

1.00

0 10 20 30 40

0

20

40

60

80

100

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 10 20 30 40

DT50 DT90 F

2 C0 Parameters

SFO 0.538 1.79 9.1 100 k 1.29

DFOP 0.538 1.79 11 100 f 0.996k0 1.29k1 0.68

IORE 0.542 1.77 9.7 100 N 0.982k 1.38

SC

SSFO

Slowt1 2

tRIORE

 194

 163

1.02

0.534
125

Halauxifen (XDEͲ729 acid; X11393729)

Aquatic Photolysis

Halauxifen-methyl in Sandy Clay Loam System

DaysHalauxifen-methyl

0

0

 1

 1

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 44

 44

 59

 59

102.

101.

49.6

46.1

34.8

19.9

25.8

21.5

1.00

0.200

0.200

0.200

0.200

0.200

0.200

1.00

1.00

1.00

0 10 20 30 40 50 60

0

20

40

60

80

100

Time

Concentration

SFO

DFOP

IORE

-20

-10

0

10

20

-20

-10

0

10

20

-20

-10

0

10

20

0 10 20 30 40 50 60

DT50 DT90 F

2 C0 Parameters

SFO 1.53 5.08 29 95.2 k 0.454

DFOP 0.865 10.5 13 102 f 0.545k0 1.98k1 0.145

IORE 1.01 9.22 18 101 N 2.01k 0.00938

SC

SSFO

Slowt1 2

tRIORE

 620

1.32e+03

4.78

2.78
126

Aerobic Soil Metabolism

Product X11393729 in Clay Loam Soil

Days X11393729

 7

 7

 14

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 104

 120

 153

 153

50.2

53.1

43.5

43.6

21.6

24.6

22.0

23.2

15.7

16.6

12.0

13.3

9.50

9.40

7.80

5.40

6.00

0 50 100 150

0

10

20

30

40

50

60

70

Time

Concentration

SFO

DFOP

IORE -5

0

5

-5

0

5

-5

0

5

0 50 100 150

DT50 DT90 F

2 C0 Parameters

SFO 33.8 112 12 56.5 k 0.0205

DFOP 19.4 134 6.7 69.8 f 0.582k0 0.0666k1 0.0107

IORE 19.5 138 6.7 70.3 N 1.79k 0.00165

SC

SSFO

Slowt1 2

tRIORE

77.3

 189

 65

41.6

Product X11393729 in Silt Loam Soil

Days X11393729

 3

 3

 7

 7

 14

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 104

 120

 120

 153

 153

48.2

51.5

32.7

33.9

17.0

16.6

4.80

6.40

3.90

4.80

3.00

3.30

1.80

3.10

1.80

2.10

1.70

1.70

1.70

1.90

0 50 100 150

0

20

40

60

Time

Concentration

SFO

DFOP

IORE -2

0

2

-2

0

2

-2

0

2

0 50 100 150

DT50 DT90 F

2 C0 Parameters

SFO 7.63 25.4 13 64.4 k 0.0908

DFOP 6.58 26.6 1.9 68.9 f 0.928k0 0.116k1 0.00804

IORE 5.1 28.4 6.6 78.1 N 1.56k 0.0143

SC

SSFO

Slowt1 2

tRIORE

30.9

86.9

86.2

8.54
127

Product X11393729 in Loam Soil

Days X11393729

 3

 3

 7

 7

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 104

 120

 120

 153

 153

38.2

41.3

16.0

16.2

6.40

3.60

3.80

2.90

2.40

1.90

2.20

1.10

1.50

1.00

1.00

1.10

1.30

0.400

0.800

0 50 100 150

0

50

100

150

Time

Concentration

SFO

DFOP

IORE

-4

-2

0

2

4

-4

-2

0

2

4

-4

-2

0

2

4

0 50 100 150

DT50 DT90 F

2 C0 Parameters

SFO 3.31 11 20 73.9 k 0.209

DFOP 2.67 10.8 2.3 86.4 f 0.931k0 0.286k1 0.0169

IORE 0.972 6.62 7.8 179 N 1.75k 0.0188

SC

SSFO

Slowt1 2

tRIORE

15.8

 70

 41

1.99

Product X11393729 in Loam Soil

Days X11393729

 3

 3

 7

 7

 14

 30

 30

 44

 44

 62

 62

 79

 79

 104

 104

 120

 120

 153

 153

38.2

41.3

16.0

16.2

6.40

3.60

3.80

2.90

2.40

1.90

2.20

1.10

1.50

1.00

1.00

1.10

1.30

0.400

0.800

0 50 100 150

0

50

100

150

Time

Concentration

SFO

DFOP

IORE

-4

-2

0

2

4

-4

-2

0

2

4

-4

-2

0

2

4

0 50 100 150

DT50 DT90 F

2 C0 Parameters

SFO 3.31 11 20 73.9 k 0.209

DFOP 2.67 10.8 2.3 86.4 f 0.931k0 0.286k1 0.0169

IORE 0.972 6.62 7.8 179 N 1.75k 0.0188

SC

SSFO

Slowt1 2

tRIORE

15.8

 70

 41

1.99
128

Anaerobic Soil Metabolism

Product X11393729 in Clay Loam Soil

DAF X11393729

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

67.5

69.2

66.8

65.7

55.6

58.9

47.2

50.9

38.2

39.4

22.7

44.6

0 20 40 60 80 100 120

0

10

20

30

40

50

60

70

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 20 40 60 80100

DT50 DT90 F

2 C0 Parameters

SFO 102 340 2.4 77.6 k 0.00678

DFOP 102 340 3 77.6 f 0.487k0 0.00678k1 0.00678

IORE 105 240 2.3 75.4 N 0.457k 0.0574

SC

SSFO

Slowt1 2

tRIORE

 356

 284

 102

72.2
129

Product X11393729 in Silt Loam Soil

DAF X11393729

 2

 2

 6

 6

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

63.6

63.6

52.8

53.3

44.1

36.6

18.9

18.2

6.60

4.90

2.60

2.20

1.90

1.90

1.50

1.70

0 20 40 60 80 100 120

0

10

20

30

40

50

60

70

Time

Concentration

SFO

DFOP

IORE

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

0 20 40 60 80100

DT50 DT90 F

2 C0 Parameters

SFO 15.2 50.6 6.4 70.6 k 0.0455

DFOP 15.2 50.6 7.4 70.6 f 0.824k0 0.0455k1 0.0455

IORE 16.6 47 5.5 68.7 N 0.787k 0.0955

SC

SSFO

Slowt1 2

tRIORE

78.7

86.7

15.2

14.1

Product X11393729 in Loam Soil

DAF X11393729

0

0

 2

 2

 6

 6

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

47.4

45.5

41.4

41.8

37.0

36.5

27.5

25.1

17.0

14.9

13.8

10.9

6.50

4.40

1.80

1.60

1.60

1.70

0 20 40 60 80 100 120

0

10

20

30

40

Time

Concentration

SFO

DFOP

IORE

-3

-2

-1

0

1

2

3

-3

-2

-1

0

1

2

3

-3

-2

-1

0

1

2

3

0 20 40 60 80100

DT50 DT90 F

2 C0 Parameters

SFO 21 69.7 4.4 44.9 k 0.033

DFOP 18.6 76.7 2.9 46.3 f 0.217k0 0.116k1 0.0268

IORE 19.1 77.4 3.3 45.8 N 1.24k 0.016

SC

SSFO

Slowt1 2

tRIORE

30.1

37.2

25.8

23.3
130

Aerobic Aquatic Metabolism

Product X11393729 in Sandy Loam Soil

DAF X11393729

 6

 6

 14

 14

 30

 30

 44

 44

 69

 69

 100

 100

 121

 121

78.9

77.3

79.6

77.0

66.6

68.2

65.5

65.4

60.1

56.9

43.5

44.3

39.0

28.9

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 20 40 60 80100

DT50 DT90 F

2 C0 Parameters

SFO 107 355 3.8 84.1 k 0.00649

DFOP 108 NA 3.3 80.4 f -4.87k0 0.0146k1 0.0126

IORE 108 332 4 83.5 N 0.899k 0.00965

SC

SSFO

Slowt1 2

tRIORE

 215

 183

 55

 100

Product X11393729 in Loamy Sand System

Days X11393729

 5

 5

 8

 8

 14

 14

 22

 22

 30

 30

 43

 43

 62

 62

 79

 79

 103

 103

20.8

23.4

23.5

12.8

14.6

13.0

3.40

7.50

1.40

8.40

3.10

4.10

2.50

2.00

2.20

2.60

1.50

2.40

0 20 40 60 80 100

0

5

10

15

20

25

30

35

Time

Concentration

SFO

DFOP

IORE

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

0 20 40 60 80 100

DT50 DT90 F

2 C0 Parameters

SFO 11.6 38.6 14 29.5 k 0.0596

DFOP 9.73 NA 9.7 32.2 f 0.943k0 0.0778k1 -0.00151

IORE 7.49 41.5 12 36.9 N 1.56k 0.015

SC

SSFO

Slowt1 2

tRIORE

 139

 135

-460

12.5
131

Anaerobic Aquatic Metabolism

Product X11393729 in Silt Loam System

Days X11393729

 2

 2

 5

 5

 8

 8

 14

 14

 22

 22

 30

 30

 43

 43

 62

 62

 79

 79

 103

 103

13.3

16.4

6.50

6.50

3.50

5.30

0.800

0.700

0.500

0.300

0.500

0.300

0.500

0.300

0.500

0.300

0.500

0.300

0.500

0.300

0 20 40 60 80 100

0

20

40

60

80

100

120

140

Time

Concentration

SFO

DFOP

IORE

-1.5

-1

-0.5

0

0.5

1

1.5

-1.5

-1

-0.5

0

0.5

1

1.5

-1.5

-1

-0.5

0

0.5

1

1.5

0 20 40 60 80 100

DT50 DT90 F

2 C0 Parameters

SFO 2.96 9.85 13 23.4 k 0.234

DFOP 0.439 1.99 11 149 f 0.11k0 0.179k1 1.83

IORE 2.14 9.43 12 28.5 N 1.32k 0.123

SC

SSFO

Slowt1 2

tRIORE

11.2

10.8

3.87

2.84

Product X11393729 in Clay Loam System

Days X11393729

 1

 1

 3

 3

 7

 7

 14

 14

 21

 21

16.8

12.1

4.60

6.20

0.300

12.5

1.20

1.20

1.00

1.00 0 5 10 15 20

0

10000

20000

30000

40000

50000

Time

Concentration

SFO

DFOP

IORE -5

0

5

-5

0

5

-5

0

5

0 5 10 15 20

DT50 DT90 F

2 C0 Parameters

SFO 3.72 12.4 28 15.5 k 0.186

DFOP 0.279 1.17 22 117 f 0.931k0 2.75k1 0.0883

IORE 0.0000136 0.00021 23 50624 N 2.44k 0.0152

SC

SSFO

Slowt1 2

tRIORE

 148

 126

7.85

6.32e-05
132

Total Residues

Aquatic Photolysis

Product X11393729 in Sandy Clay Loam System

Days X11393729

 3

 3

 7

 7

 14

 14

42.1

22.3

23.5

21.5

1.00

1.00

0 2 4 6 8 10 12 14

0

10

20

30

40

50

60

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 2 4 6 8 1012 14

DT50 DT90 F

2 C0 Parameters

SFO 4.4 14.6 19 54.1 k 0.158

DFOP 2.77 13 NaN 70 f 0.773k0 0.158k1 4.89

IORE 8.16 13.3 Inf 39 N -0.239k 5.35

SC

SSFO

Slowt1 2

tRIORE

 396

 293

 4.4

4.01
133

Aerobic Soil Metabolism
134
135

Anaerobic Soil Metabolism
136
137

Aerobic Aquatic Metabolism
138

Anaerobic Aquatic Metabolism
139

Total Residues Plus Unextracted Residues

Aerobic Soil Metabolism
140
141
142

Anaerobic Soil Metabolism
143
144

Aerobic Aquatic Metabolism
145

APPENDIX D. HalauxifenͲmethyl Transformation Product Summary

Table D.1. Chemical Identification and Environmental Formation Summary for HalauxifenͲmethyl and CorrespondingEnvironmental Transformation ProductsA

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

PARENT

HalauxifenͲmethyl

XDEͲ729

XDEͲ729 methyl

X11393728XRͲ729 methyl

XDEͲ729 ME

IUPAC: Methyl 4Ͳ

aminoͲ3ͲchloroͲ6Ͳ(4Ͳ

chloroͲ2ͲfluoroͲ3Ͳ

methoxyphenyl)pyridineͲ2Ͳcarboxylate

CAS: Methyl 4Ͳ

aminoͲ3ͲchloroͲ6Ͳ(4Ͳ

chloroͲ2ͲfluoroͲ3Ͳ

methoxyphenyl)Ͳ2Ͳ

pyridinecarboxylateCAS No.: 943831Ͳ98Ͳ

9

Formula:

C14H11Cl2FN O2 3

MW: 345.16 g/mol

SMILES:COc1c(ccc(c1F)c2cc(c(c(n2)C(=O)OC)Cl)N)Cl

F

O

CH3

Cl

O

O

C H3

Cl

N H2N

835.2120

Hydrolysis 48557729

pH 4, 10°C 99.5% (1 d) 91.5% (30 d)pH 7, 10°C 99.6% (1 d) 96.6% (30 d)pH 9, 10°C 95.2% (0 d) 27.9% (30 d)pH 4, 25°C 99.0% (0 d) 77.1% (30 d)pH 7, 25°C 99.5% (0 d) 86.4% (30 d)pH 9, 25°C 95.2% (0 d) ND (30 d)pH 4, 50°C 99.0% (0 d) 18.1% (30 d)pH 7, 50°C 99.5% (0 d) 29.8% (30 d)pH 9, 50°C 95.2% (0 d) ND (30 d)

835.2240

Aqueous

photolysis

48557731

pH 7 100.0% (0 d) ND (15 d)

Natural water 92.7% (0 d) ND (14 d)

835.2410

Soil photolysis 48557734 Silt loam

97.9% (0 d)

Irradiated

97.9% (0 d)

Control

41.0% (15 d)

Irradiated

3.0% (15 d)

Control

835.4100

Aerobic soil

metabolism

48557735

Clay loam 98.1% (0 d) 2.0% (153 d)

Loam 97.8% (0 d) 0.8% (153 d)

Silt loam 94.7% (0 d) 1.0% (153 d)

Sandy loam 98.5% (0 d) NR (153 d)

835.4200

Anaerobic soil

metabolism

48557736

Clay loam

Aerobic: 93.8% (0 d) 2.0% (123 d) Anaerobic: 52.1% (2 d)

Loam

Aerobic: 92.4% (0 d) 0.6% (123 d) Anaerobic: 26.4% (2 d)

Silt loam Aerobic: 91.3% (0 d) 0.4% (123 d)
146

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

Anaerobic: 66.6% (2 d)

Sandy loam

Aerobic: 93.5% (0 d) 0.5% (123 d) Anaerobic: 20.2% (2 d)

835.4300

Aerobic aquatic

metabolism

48557738

Lake water/loamy sand 89.7% (0 d) 0.4% (103 d)

Lake water/silt loam 94.7% (0 d) 0.1% (103 d)

835.4400

Anaerobic aquatic

metabolism

48557739

River water/clay loam 105.4% (0 d) 0.0% (100 d)

Natural water/sandy clay loam 102.1% (0 d) 0.0% (100 d)

MAJOR (>10%) TRANSFORMATION PRODUCTS

X11393729X’729XDEͲ729 acidHalauxifen acid

835.2120

Hydrolysis 48557729

pH 4, 10°C 8.1% (30 d) 8.1% (30 d)

pH 7, 10°C 3.7% (30 d) 3.7% (30 d)pH 9, 10°C 72.0% (30 d) 72.0% (30 d)pH 4, 25°C 23.7% (30 d) 23.7% (30 d)pH 7, 25°C 13.0% (30 d) 13.0% (30 d)pH 9, 25°C 99.3% (30 d) 99.3% (30 d)pH 4, 50°C 83.3% (30 d) 83.3% (30 d)pH 7, 50°C 70.3% (30 d) 70.3% (30 d)pH 9, 50°C 99.6% (3, 7, 21 d) 99.2% (30 d)

835.2240

Aqueous

photolysis

48557731

pH 7 8.9% (14 d) Dark Control 8.9% (14 d) Dark Control

Natural water

10.7%

(0.007 d)

Irradiated

80.3% (14 d)

Dark Control

ND (14 d)

Irradiated

80.3% (14 d)

Dark Control

835.2410

Soil photolysis 48557734 Silt loam

49.1% (15 d)

Irradiated

72.5% (7 d)

Control

49.1% (15 d)

Irradiated

47.1% (15 d)

Control

48557735 Clay loam 53.1% (7 d) 6.0% (153 d)
147

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

IUPAC: 4ͲAminoͲ3Ͳ

chloroͲ6Ͳ(4ͲchloroͲ2Ͳ

fluoroͲ3Ͳ

methoxyphenyl)pyridineͲ2Ͳcarboxylic

acidCAS: 2Ͳ

Pyridinecarboxylicacid, 4ͲaminoͲ3Ͳ

chloroͲ6Ͳ(4ͲchloroͲ2Ͳ

fluoroͲ3Ͳ

methoxyphenyl)ͲCAS No.: 943832Ͳ60Ͳ

8Formula:C13H9Cl2FN O2 3

MW: 331.13 g/mol

SMILES:COc1c(ccc(c1F)c2cc(c(c(n2)C(=O)O)Cl)N)Cl

835.4100

Aerobic soil

metabolism

Loam 41.3% (3 d) 0.8% (153 d)

Silt loam 51.5% (3 d) 1.9% (153 d)

Sandy loam 72.7% (3 d) NR (153 d)

835.4200

Anaerobic soil

metabolism

48557736

Clay loam 69.2% (16 d) 44.6% (123 d)

Loam 47.4% (2 d) 1.7% (123 d)

Silt loam 63.6% (4 d) 1.7% (123 d)

Sandy loam 79.6% (16 d) 39.0% (123 d)

835.4300

Aerobic aquatic

metabolism

48557738

Lake water/loamy sand 23.5% (8 d) 2.4% (103 d)

Lake water/silt loam 16.4% (2 d) 0.0% (103 d)

835.4400

Anaerobic aquatic

metabolism

48557739

River water/clay loam 16.8% (1 d) 0.0% (100 d)

Natural water/sandy clay loam 42.1% (3 d) 0.0% (100 d)

X11449757 (X’757,

DesͲmethylͲXRͲ729,

DesͲmethyl XDEͲ

729, X757)

IUPAC: 4ͲAminoͲ3Ͳ

chloroͲ6Ͳ(4ͲchloroͲ2Ͳ

fluoroͲ3Ͳ

hydroxyphenyl)picolinic acid

CAS: 4ͲAminoͲ3Ͳ

chloroͲ6Ͳ(4ͲchloroͲ2Ͳ

835.2410

Soil photolysis 48557734 Silt loam

6.8% (15 d)

Irradiated

12.7% (12 d)

Control

6.8% (15 d)

Irradiated

12.6% (15 d)

Control

835.4100

Aerobic soil

metabolism 48557735

Clay loam 5.0% (14 d) 1.2% (153 d)

Loam 17.4% (7 d) 1.5% (153 d)

Silt loam 10.8% (7 d) 1.7% (153 d)

Sandy loam 3.1% (3 d) NR (153 d)
148

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

fluoroͲ3Ͳ

hydroxyphenyl)Ͳ

pyridineͲ2ͲcarboxylicacidFormula:C12H7Cl2FN O2 3

MW: 317.11 g/mol

SMILES:c1cc(c(c(c1c2cc(c(c(n2)C(=O)O)Cl)N)F)O)Cl

835.4200

Anaerobic soil

metabolism 48557736

Clay loam 41.4% (123 d) 41.4% (123 d)

Loam 54.3% (123 d) 54.3% (123 d)

Silt loam 46.1% (102 d) 39.3% (123 d)

Sandy loam 46.8% (123 d) 46.8 (123 d)

835.4300

Aerobic aquatic

metabolism 48557738

Lake water/loamy sand 75.6% (22 d) 16.3% (103 d)

Lake water/silt loam 76.7% (8 d) 43.3% (103 d)

X11406790 (X’790,

X790)

CAS: Methyl 4Ͳ

aminoͲ3ͲchloroͲ6Ͳ(4Ͳ

chloroͲ2ͲfluoroͲ3Ͳ

hydroxyphenyl)pyridineͲ2Ͳcarboxylate

Formula:

C13H9Cl2FN O2 3

MW: 331.13 g/mol

SMILES:COC(=O)c1c(c(cc(n1)c2ccc(c(c2F)O)Cl)N)Cl

835.4100

Aerobic soil

metabolism 48557735

Clay loam 1.4% (1, 3 d) 0.2% (153 d)

Loam 0.9% (1 d) 0.0% (153 d)

Silt loam 1.1% (3 d) 0.2% (153 d)

Sandy loam 0.8% (1 d) NR (153 d)

835.4200

Anaerobic soil

metabolism 48557736

Clay loam 1.5% (2 d) 0.0% (123 d)

Loam 0.9% (2 d) 0.0% (123 d)

Silt loam 2.7% (2 d) 0.0% (123 d)

Sandy loam 0.5% (2 d) 0.0% (123 d)

835.4300

Aerobic aquatic

metabolism 48557738

Lake water/loamy sand 23.4% (5 d) 0.6% (103 d)

Lake water/silt loam 23.6% (2 d) 0.2% (103 d)

835.4400

Anaerobic aquatic

metabolism 48557739

River water/clay loam 31.9% (1 d) 0.0% (100 d)

Natural water/sandy clay loam 32.7% (3 d) 0.0% (100 d)

Degradate 11 835.2240

Aqueous

photolysis 48557731

pH 7 41.2% (14 d) 35.0% (15 d)

Natural water 20.4% (7 d) 20.0% (14 d)

Degradate 21 835.2240 48557731 Natural water 12.6% (3 d) 8.0% (14 d)
149

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

Aqueous

photolysis

Degradate 41

NA NA

835.2240

Aqueous

photolysis 48557731 Natural water 14.6% (0.06 d) 0.7% (14 d)

Degradate 102 IUPAC: Methyl 4Ͳ

aminoͲ6Ͳ(4ͲchloroͲ2Ͳ

fluoroͲ3ͲmethoxyͲ

phenyl)Ͳ3ͲhydroxyͲ

pyridineͲ2ͲcarboxylateFormula:C14H12ClFN O2 4

MW: 326 g/mol

SMILES:COc1c(ccc(c1F)c2cc(c(c(n2)C(=O)OC)O)N)Cl

835.2240

Aqueous

photolysis 48557731 pH 7 12.6% (0.01 d) ND (15 d)

Degradate 112 IUPAC: Methyl (2E)Ͳ

2Ͳ(4ͲchloroͲ2ͲfluoroͲ

3ͲmethoxyͲ

benzoyl)iminoacetateFormula:C11H9ClFNO4

MW: 273 g/mol

835.2240

Aqueous

photolysis 48557731

pH 7 15.7% (0.01 d) ND (15 d)

Natural water 13.8% (0.02 d) ND (14 d)
150

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

SMILES:COc1c(ccc(c1F)C(=O)/N=C/C(=O)OC)Cl

Degradate 142 IUPAC: 2Ͳ[(E)Ͳ(4Ͳ

chloroͲ2ͲfluoroͲ3Ͳ

methoxyͲphenyl)methyleneamino]acetaldehydeFormula:C10H9ClFNO2

MW: 229 g/molSMILES:COc1c(ccc(c1F)/C=N/CC=O)Cl

835.2240

Aqueous

photolysis 48557731 pH 7 11.5% (0.09 d) ND (15 d)

Carbon dioxide IUPAC: Carbon

dioxideFormula: CO2

MW: 44 g/mol

SMILES: C(=O)=O

835.2240 Aqueous

photolysis 48557731 pH 7 43.6% (14 d) 42.1% (15 d) Natural water 57.5% (14 d) 57.5% (14 d)

835.2410

Soil photolysis 48557734 Silt loam

4.9% (15)

Irradiated

4.0% (15 d)

Control

4.9% (15)

Irradiated

4.0% (15 d)

Control

835.4100

Aerobic soil

metabolism 48557735

Clay loam 22.2% (153 d) 22.2% (153 d)

Loam 23.9% (153 d) 23.9% (153 d)

Silt loam 26.3% (153 d) 26.3% (153 d)

Sandy loam 37.9% (120 d) NR (153 d)

835.4200

Anaerobic soil

metabolism

48557736

Clay loam 0.8% (46 d) 0.4% (123 d)

Loam 0.8% (16, 46, 102 d) 0.7% (123 d)
151

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

Silt loam 0.6% (4 d) 0.4% (123 d)

Sandy loam 1.0% (123 d) 1.0% (123 d)

835.4300

Aerobic aquatic

metabolism 48557738

Lake water/loamy sand 15.8% (103 d) 15.8% (103 d)

Lake water/silt loam 2.1% (79 d) 1.2% (103 d)

835.4400

Anaerobic aquatic

metabolism 48557739

River water/clay loam 0.4% (80 d) 0.2% (100 d)

Natural water/sandy clay loam 0.3% (80 d) 0.2% (100 d)

Unextractedresidues

NA NA

835.2410

Soil photolysis 48557734 Silt loam

19% (12 d)

Irradiated

34.8% (15 d)

Control

15.9% (15 d)

Irradiated

34.8% (15 d)

Control

835.4100

Aerobic soil

metabolism

48557735

Clay loam 78.4% (153 d) 78.4% (153 d)

Loam 87.0% (62 d) 82.1% (153 d)

Silt loam 83.4% (79 d) 74.9% (153 d)

Sandy loam 62.5% (104 d) NR (153 d)

835.4200

Anaerobic soil

metabolism

48557736

Clay loam 48.4% (123 d) 48.4% (123 d)

Loam 57.2% (123 d) 57.2% (123 d)

Silt loam 64.8% (123 d) 64.8% (123 d)

Sandy loam 28.3% (46 d) 23.8% (123 d)

835.4300

Aerobic aquatic

metabolism 48557738

Lake water/loamy sand 72.4% (79 d) 54.8% (103 d)

Lake water/silt loam 56.6% (8 d) 51.2% (103 d)

835.4400

Anaerobic aquatic

metabolism

48557739 River water/clay loam 9.2 (59 d) 7.0 (100 d)
152

Code Name/

Synonym Chemical Name Chemical Structure Study Type

MRID/

Classificat

ion

Maximum %AR (day) Final %AR (study length)

MINOR (<10%) TRANSFORMATION PRODUCTS

X11861662 (X’662) CAS: Methyl 4Ͳ

aminoͲ6Ͳ(4ͲchloroͲ2Ͳ

fluoroͲ3Ͳ

methoxyphenyl)pyridineͲ2Ͳcarboxylate

Formula:

C14H12ClFN O2 3

MW: 310.71 g/mol

SMILES:COc1c(ccc(c1F)c2cc(cc(n2)C(=O)OC)N)Cl

835.2240

Aqueous

photolysis 48557731

pH 7 6.7% (0.02 d) ND (15 d)

Natural water 8.4% (0.08 d) ND (14 d)

Degradate 9 CAS:

Formula:MW: g/molSMILES:

835.2240

Aqueous

photolysis

48557731 pH 7 7.1% (0.008 d) 0.6% (14 d)

REFERENCE COMPOUNDS NOT IDENTIFIED

All compounds used as reference compounds were identified.

A AR means “applied radioactivity”. MW means “molecular weight”. ND means “not detected”. NR means “1 Unidentified polar compound; structure not proposed.2Unidentified polar compound; MW and chemical composition determined by Mass Spectrometry (MS)
APPENDIX E. Summary of Total HalauxifenͲmethyl Residues

Table E.1. Environmental Fate Parameters of Total HalauxifenͲmethyl Residues

Study System Name/ Characteristics

Kinetic Model Fitteda Value and

Unit (Fitting Equation)

HalfͲlife Value

Used to Derive

Model Input Values

(days)bͲͲ

Source/ Classification Comments

DT50 (days) DT90 (days)

Hydrolysis

pH 4, 25°C

No substantial degradation

(pH 4, 7, and 9)

835.2010

MRID 48557729

Acceptable

pH 7, 25°CpH 9, 25°C

Aqueous

Photolysis pH 7, 25qC 25.2 (DFOP) 114 (DFOP) Slow t1/2=38.4

835.2240

MRID 48557731

Supplemental

Model fitting of the TTR using

a summation approach did notprovide reasonable results due

to the formation and decline of

multiple and nonͲsequential

transformation products

considered as part of the TTR.

A degradation rate was

calculated by subtracting out

the amount of CO2 formed

from the amount of material

applied (time 0) for the study

duration. The halfͲlife value

was not adjusted as CO2

formation was not observed in

the control experiments.

Soil Photolysis

Silt loam soil

(28qC, pH 5.9,

6.2% OM)

Not

determinable

Not

determinable Not applicable

835.2410

MRID 48557734

Supplemental

See Table 4.

Aerobic Soil

Metabolism

California

Clay loam soil

(20oC, pH 7.1

19.8 (IORE)

321 (SFO)

136 (IORE)

1065 (SFO)

TIORE=40.9

t1/2=321

835.4100

MRID 48557735

Supplemental

See Table 4.
154

Study System Name/ Characteristics

Kinetic Model Fitteda Value and

Unit (Fitting Equation)

HalfͲlife Value

Used to Derive

Model Input Values

(days)bͲͲ

Source/ Classification Comments

DT50 (days) DT90 (days)

2.2% OM)

Germany

Loam soil

(20oC, pH 5.0, 4.3% OM)

5.97 (IORE)

298 (SFO)

35.7 (IORE)

960 (SFO)

TIORE=10.7

t1/2=298

United Kingdom Silt loam soil (20oC,

pH 5.9, 6.2% OM)

7.72 (IORE)

338 (SFO)

44.2 (IORE)

1122 (SFO)

TIORE=13.3

t1/2=338

United Kingdom Sandy loam soil

(20oC, pH 7.5, 2.4% OM)

9.83 (IORE)

229 (DFOP)

55.4 (IORE)

1388 (DFOP)

TIORE=16.7

Slow t1/2=499

Anaerobic Soil

Metabolism

California Clay loam soil flooded

with HPLC grade water (20oC, pH

7.1)

235 (SFO)

1519 (SFO)

781 (SFO)

5045 (SFO)

t1/2=235

t1/2=1519

835.4200

MRID 48557736

Supplemental

See Table 4.

Germany Loam soil flooded with

HPLC grade water (20oC, pH 5.0)

170 (IORE)

1597 (SFO)

17511 (IORE)

5304 (SFO)

TIORE=5270

t1/2=1897

United Kingdom Silt loam soil

flooded with HPLC grade water

(20oC, pH 5.9)

78.8 (IORE)

1902 (SFO)

1304 (IORE)

6318 (SFO)

TIORE=393

t1/2=1902

United Kingdom Sandy loam soil

flooded with HPLC grade water

(20oC, pH 7.5)

510 (SFO)

1551 (SFO)

1694 (SFO)

5152 (SFO)

t1/2=510

t1/2=1551

Aerobic

Aquatic

England lake water:loamy sand

sediment (20oC, water pH 7.0,

sediment pH 5.8)

52 (SFO)

58.7 (IORE)

233 (SFO)

173 (SFO)

107 (IORE)

775 (SFO)

t1/2=52

TIORE=32.3

t1/2=233

835.4300

MRID 48557738

supplemental

Approximately 20% of the

applied radioactivity remained

at study termination (103 d) as

well as the second to the last

sampling interval (79 d)

suggesting that transformationslowed at the end of the

experiment. The IORE N

parameter value is less than

one. Selected SFO.
155

Study System Name/ Characteristics

Kinetic Model Fitteda Value and

Unit (Fitting Equation)

HalfͲlife Value

Used to Derive

Model Input Values

(days)bͲͲ

Source/ Classification Comments

DT50 (days) DT90 (days)

England lake water:silt loam

sediment (20oC, water pH 8.3,

sediment pH 7.7)

61.7 (DFOP)

0

614 (DFOP)

0

Slow t1/2=257

0

The measured concentrations

of TTR+UE are within the

observed experimental error.

Therefore, the TTR+UE are

expected to be stable.

Anaerobic

Aquatic

North Dakota river water:clay loam

sediment (20oC, water pH 8.2,

sediment pH 8.1) No significant transformation was observed

834.4400

MRID

117501

Supplemental

The measured concentrations

are within the observedexperimental error. Therefore,

the TTR is expected to be

stable. See Table 4

Wyoming natural water:sandy clay

loam sedimentc (20oC, water pH 8.2,

sediment pH 8.3)

Terrestrial Field

Dissipation Could not be determined.

835.6100

MRID 49022101

Supplemental

Not all residues considered as

part of the total residues were

monitored for in the terrestrial

field dissipation studies.

a. DT50 and DT90 values were calculated using single firstͲorder (SFO), double firstͲ order in parallel (DFOP), or indeterminateͲ order equation (IORE). For DFOP, the

overall DT50 and DT90 are reported when available. The equations can be found in the document, Standard Operating Procedure for Using the NAFTA Guidance to

Calculate Representative HalfͲlife Values and Characterize Pesticide Degradation, U.S. Environmental Protection Agency, March 23, 2015

b. The value used to estimate a model input value is the calculated SFO DT50, TIORE, or the 2nd DT50 from the DFOP equation. The model chosen is consistent with that

recommended using the, Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media, Health Canada, U.S. Environmental Protection Agency,

December 21, 2012. The same model used to estimate the value used to derive a model input, is used to describe the DT50 and DT90 results.

c. Data for day three are inconsistent; see graph in DER

d. Data provided in italic font is for TTR plus unextracted residues (or TTR+EU).
APPENDIX F. Sample TͲREX Inputs and Outputs for the Proposed Uses of HalauxifenͲmethyl

Chemical Identity and Application Information

Chemical Name: HalauxifenͲmethyl

Seed Treatment? (Check if yes)  FALSE

Use: 10

Product name and form: GFͲ2685

% A.I. (leading zero must be entered for formulations

<1% a.i.): 100.00%

Application Rate (lb ai/acre) 0.0091 

HalfͲlife (days): 35 

Application Interval (days): 10 

Number of Applications: 2 

Are you assessing applications with variable rates or

intervals? no 

Avian

 

Endpoint Toxicity value Indicate test species below

LD50 (mg/kgͲbw)

2250.00 1

LC50 (mg/kgͲdiet) 4858.00 1

NOAEL (mg/kgͲbw)  1

NOAEC (mg/kgͲdiet) 403.00 1

Enter the Mineau et al. Scaling Factor 1.15

Mammalian  

  Acute Study

Size (g) of mammal used in toxicity study

Default rat body weight is 350 grams

350

Endpoint Toxicity value

LD50 (mg/kgͲbw) 5000.00 

LC50 (mg/kgͲdiet)  
157

Reported Chronic Endpoint 103.00

1

Is dietary concentration (mg/kgͲ

diet) reported from the available

chronic mammal study? (yes or

no)

NO



 
158

Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs

    

Table 1. Upper Bound Kenaga, Acute Avian DoseͲBasedRisk Quotients

Size

Class

(grams)

Adjusted

LD50

EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 1620.97 4.53 0.00 2.08 0.00 2.55 0.00 0.28 0.00 1.77 0.00 0.06 0.00

100 2063.57 2.58 0.00 1.18 0.00 1.45 0.00 0.16 0.00 1.01 0.00 0.04 0.00

1000 2914.87 1.16 0.00 0.53 0.00 0.65 0.00 0.07 0.00 0.45 0.00 0.02 0.00

    

Table 2.Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients  

LC50

EECs and RQs  

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds Arthropods 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ  

4858 3.98 0.00 1.82 0.00 2.24 0.00 0.25 0.00 1.56 0.00 

Size class not used for dietary risk quotients  

     

Table 3.Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients  

NOAEC

(ppm)

EECs and RQs  

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds Arthropods 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ  

403 3.98 0.01 1.82 0.00 2.24 0.01 0.25 0.00 1.56 0.00 

Size class not used for dietary risk quotients   

     

Table 4. Upper Bound Kenaga, AcuteMammalian DoseͲBasedRisk Quotients

Size

Class

(grams)

Adjusted

LD50

EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 10989.15 3.79 0.00 1.74 0.00 2.13 0.00 0.24 0.00

1.4

8

0.000

1 0.05 5EͲ06

35 8891.40 2.62 0.00 1.20 0.00 1.47 0.00 0.16 0.00

1.0

2

0.000

1 0.04 4EͲ06

1000 3845.80 0.61 0.00 0.28 0.00 0.34 0.00 0.04 0.00

0.2

3 6EͲ05 0.01 2EͲ06

            

    

Table 5.Upper Bound Kenaga, Acute Mammalian Dietary Based Risk Quotients  

LC50

(ppm)

EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/Seeds Arthropods  

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ  

0 3.98

#DIV

/0! 1.82

#DIV

/0! 2.24

#DIV/0

! 0.25 ##### 1.56

#DI

V/0

!  

Size class not used for dietary risk quotients 

     

Table 6.Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients  

NOAEC

(ppm)

EECs and RQs  

Short Grass Tall Grass Broadleaf

Plants

Fruits/Pods/Seeds/La

rge Insects Arthropods  

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ  

2060 3.98 0.00 1.82 0.00 2.24 0.00 0.25 0.00 1.56

0.0

0  

Size class not used for dietary risk quotients     

           
159

Table 7.Upper Bound Kenaga, Chronic Mammalian DoseͲBased Risk Quotients

Size

Class

(grams)

Adjusted

NOAEL

EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 226.38 3.79 0.02 1.74 0.01 2.13 0.01 0.24 0.00 1.48 0.01 0.05 0.00

35 183.16 2.62 0.01 1.20 0.01 1.47 0.01 0.16 0.00 1.03 0.01 0.04 0.00

1000 79.22 0.61 0.01 0.28 0.00 0.34 0.00 0.04 0.00 0.24 0.00 0.01 0.00

 
160

APPENDIX G. TerrPlant Inputs and Outputs for the Proposed HalauxifenͲmethyl Uses

TerrPlant v. 1.2.2    

Green values signify user inputs (Tables 1, 2 and 4).  

Input and output guidance is in popups indicated by red arrows.  

    

Table 1. Chemical Identity. 

Parameter User Inputs 

Chemical Name HalauxifenͲmethyl Formulation GFͲ2685 

PC code 117501 

Use Barley, Wheat, Triticale 

Application Method Aerial Spray 

Application Form Liquid 

Solubility in Water (ppm) 1.8 

    

Table 2. Input parameters used to derive EECs. 

Input Parameter Symbol Value (user inputs) Units 

Application Rate A 0.0087 lbs a.e./A 

Incorporation I 1 none 

Runoff Fraction R 0.01 none 

Drift Fraction D 0.05 none 

    

Table 3. EECs for HalauxifenͲmethyl Formulation GFͲ2685.Units in lbs a.e./A. 

Description Equation EEC 

Runoff to dry areas (A/I)*R 0.000087 

Runoff to semiͲaquatic areas (A/I)*R*10 0.00087 

Spray drift A*D 0.000435 

Total for dry areas ((A/I)*R)+(A*D) 0.000522 

Total for semiͲaquatic areas ((A/I)*R*10)+(A*D) 0.001305 

    

Table 4. Plant survival and growth data used for RQ derivation. Units are in lbs a.e./A. All values are user

inputs

 Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC

Monocot 0.00394 0.00111 0.000128 0.0000122

Dicot 0.00181 0.000558 0.0000102 0.00000872

    

Table 5. RQ values for plants in dry and semiͲaquatic areas exposed to HalauxifenͲmethyl Formulation GFͲ

2685 through runoff and/or spray drift.*

Plant Type Listed Status Dry SemiͲAquatic Spray Drift

Monocot nonͲlisted 0.1 0.3 3.4

Monocot listed 0.5 1.2 35.7

Dicot nonͲlisted 0.3 0.7 42.6
161

Dicot listed 0.9 2.3 49.9

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

TerrPlant v. 1.2.2    

Green values signify user inputs (Tables 1, 2 and 4).  

Input and output guidance is in popups indicated by red arrows.  

    

Table 1. Chemical Identity. 

Parameter User Inputs 

Chemical Name HalauxifenͲmethyl Formulation GFͲ2685 

PC code 117501 

Use Barley, Wheat, Triticale 

Application Method Ground Spray 

Application Form Liquid 

Solubility in Water (ppm) 1.8 

    

Table 2. Input parameters used to derive EECs. 

Input Parameter Symbol Value (user inputs) Units 

Application Rate A 0.0087 lbs a.e./A 

Incorporation I 1 none 

Runoff Fraction R 0.01 none 

Drift Fraction D 0.01 none 

    

Table 3. EECs for HalauxifenͲmethyl Formulation GFͲ2685.Units in lbs a.e./A. 

Description Equation EEC 

Runoff to dry areas (A/I)*R 0.000087 

Runoff to semiͲaquatic areas (A/I)*R*10 0.00087 

Spray drift A*D 0.000087 

Total for dry areas ((A/I)*R)+(A*D) 0.000174 

Total for semiͲaquatic areas ((A/I)*R*10)+(A*D) 0.000957 

    

Table 4. Plant survival and growth data used for RQ derivation. Units are in lbs a.e./A. All values are user

inputs

 Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC

Monocot 0.00394 0.00111 0.000128 0.0000122

Dicot 0.00181 0.000558 0.0000102 0.00000872

    

Table 5. RQ values for plants in dry and semiͲaquatic areas exposed to HalauxifenͲmethyl Formulation GFͲ

2685 through runoff and/or spray drift.*

Plant Type Listed Status Dry SemiͲAquatic Spray Drift

Monocot nonͲlisted <0.1 0.2 0.7

Monocot listed 0.2 0.9 7.1
162

Dicot nonͲlisted <0.1 0.5 8.5

Dicot listed 0.3 1.7 10.0

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

TerrPlant v. 1.2.2    

Green values signify user inputs (Tables 1, 2 and 4).  

Input and output guidance is in popups indicated by red arrows.  

    

Table 2. Chemical Identity. 

Parameter User Inputs 

Chemical Name HalauxifenͲmethyl Formulation GFͲ2687 

PC code 117501 

Use Barley, Wheat, Triticale 

Application Method Aerial Spray 

Application Form Liquid 

Solubility in Water (ppm) 1.8 

    

Table 2. Input parameters used to derive EECs. 

Input Parameter Symbol Value (user inputs) Units 

Application Rate A 0.0087 lbs a.e./A 

Incorporation I 1 none 

Runoff Fraction R 0.01 none 

Drift Fraction D 0.05 none 

    

Table 3. EECs for HalauxifenͲmethyl Formulation GFͲ2687.Units in lbs a.e./A. 

Description Equation EEC 

Runoff to dry areas (A/I)*R 0.000087 

Runoff to semiͲaquatic areas (A/I)*R*10 0.00087 

Spray drift A*D 0.000435 

Total for dry areas ((A/I)*R)+(A*D) 0.000522 

Total for semiͲaquatic areas ((A/I)*R*10)+(A*D) 0.001305 

    

Table 4. Plant survival and growth data used for RQ derivation. Units are in lbs a.e./A. All values are user inputs

 Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC

Monocot 0.000767 0.000534 0.00154 0.00111

Dicot 0.000185 0.000133 0.0000104 0.000000095

    

Table 5. RQ values for plants in dry and semiͲaquatic areas exposed to HalauxifenͲmethyl Formulation GFͲ2687

through runoff and/or spray drift.*

Plant Type Listed Status Dry SemiͲAquatic Spray Drift
163

Monocot nonͲlisted 0.7 1.7 0.6

Monocot listed 1.0 2.4 0.8

Dicot nonͲlisted 2.8 7.1 41.8

Dicot listed 3.9 9.8 4578.9

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

TerrPlant v. 1.2.2    

Green values signify user inputs (Tables 1, 2 and 4).  

Input and output guidance is in popups indicated by red arrows.  

    

Table 1. Chemical Identity. 

Parameter User Inputs 

Chemical Name HalauxifenͲmethyl Formulation GFͲ2687 

PC code 117501 

Use Barley, Wheat, Triticale 

Application Method Ground Spray 

Application Form Liquid 

Solubility in Water (ppm) 1.8 

    

Table 2. Input parameters used to derive EECs. 

Input Parameter Symbol Value (user inputs) Units 

Application Rate A 0.0087 lbs a.e./A 

Incorporation I 1 none 

Runoff Fraction R 0.01 none 

Drift Fraction D 0.01 none 

    

Table 3. EECs for HalauxifenͲmethyl Formulation GFͲ2687.Units in lbs a.e./A. 

Description Equation EEC 

Runoff to dry areas (A/I)*R 0.000087 

Runoff to semiͲaquatic areas (A/I)*R*10 0.00087 

Spray drift A*D 0.000087 

Total for dry areas ((A/I)*R)+(A*D) 0.000174 

Total for semiͲaquatic areas ((A/I)*R*10)+(A*D) 0.000957 

    

Table 4. Plant survival and growth data used for RQ derivation. Units are in lbs a.e./A. All values are user

inputs

 Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC

Monocot 0.000767 0.000534 0.00154 0.00111

Dicot 0.000185 0.000133 0.0000104 0.000000095

    

Table 5. RQ values for plants in dry and semiͲaquatic areas exposed to HalauxifenͲmethyl Formulation GFͲ

2687 through runoff and/or spray drift.*
164

Plant Type Listed Status Dry SemiͲAquatic Spray Drift

Monocot nonͲlisted 0.2 1.2 0.1

Monocot listed 0.3 1.8 0.2

Dicot nonͲlisted 0.9 5.2 8.4

Dicot listed 1.3 7.2 915.8

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.
165

APPENDIX H. Calculations for Potential Exposure from Residues in Irrigation Water

To estimate exposure to plants when groundwater contaminated with halauxifen (XDEͲ729 acid) and total

halauxifen residues is applied to crops, the following method was used.

Assume a field is irrigated with one inch of water containing residues. 

One acre has 6,272,640 cubic inches of water on the field.The 1 acre field with 1 inch of water has 3,630 cubic ft

of water (6,272,640 x 0.00058 cubic ft/cubic inch). The field has 27,156 gallons of water (3,630 cubic ft x 7.481

gallons/cubic ft). Therefore, 1 inch of water on the 1 acre field weighs 226,625 lbs (27,156 gallons x 8.3453

lbs/gallon of water).

Maximum peak estimate halauxifen (XDEͲ729 acid) in groundwater using PRZMͲGW

Assume 0.76 μg a.e./L 226,625 lb of water/acre x 0.76 μg/L=0.000217 lb a.e./A

   1,000,000,000 

Maximum peak estimate total XDEͲ729 acid residues in surface water using SWCC

Assume 0.19 μg a.e./L 226,625 lb of water/acre x 0.19 μg/L =0.00004 lbs a.e./A

   1,000,000,000 

 
166

APPENDIX I. Spray Drift Analyses

This appendix provides the terrestrial plant RQs for different distances, spray droplet sizes that

arise from aerial, and a few ground application scenarios. RQs in Tables IͲ2 – IͲ14 were

generated using EECs based on aerial applications (Tables IͲ2 – IͲ9 using the most sensitive

NOAEC or IC05; Tables IͲ10 – IͲ14 using the most sensitive vegetative vigor IC25). Similar RQs

were generated for the respective IC05 or IC25 using EECs based on ground sprays (Tables IͲ16

– I – 28). RQsш1 indicate an exceedance of the plant LOC (listed and nonlisted).

Table IͲ1. Estimated Spray Drift Residues from Aerial Applications (Acid Equivalent)

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 0.0037415 0.0031659 0.0025903 0.0023024 0.0019187 0.001535 0.0012472 0.0010553 0.0008634

F2M Air 0.0028781 0.0019187 0.001535 0.0010553 0.0008634 0.0005756 0.0003837 0.0002878 0.0002878

M2C Air 0.0025903 0.001439 0.0009594 0.0006715 0.0004797 0.0002878 0.0001919 0.0001919 9.594EͲ05

C2VC Air 0.0023984 0.0012472 0.0006715 0.0004797 0.0002878 0.0001919 9.594EͲ05 9.55EͲ05 7.67EͲ05

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A

          

Table IͲ2   

GFͲ2685 Monocot Seedling Emergence Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 3.4 2.9 2.3 2.1 1.7 1.4 1.1 1.0 0.8

F2M Air 2.6 1.7 1.4 1.0 0.8 0.5 0.3 0.3 0.3

M2C Air 2.3 1.3 0.9 0.6 0.4 0.3 0.2 0.2 0.1

C2VC Air 2.2 1.1 0.6 0.4 0.3 0.2 0.1 0.1 0.1

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.00111 lb a.e./A

Table IͲ3          

GFͲ2685 Monocot Vegetative Vigor Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 306.7 259.5 212.3 188.7 157.3 125.8 102.2 86.5 70.8

F2M Air 235.9 157.3 125.8 86.5 70.8 47.2 31.5 23.6 23.6

M2C Air 212.3 118.0 78.6 55.0 39.3 23.6 15.7 15.7 7.9

C2VC Air 196.6 102.2 55.0 39.3 23.6 15.7 7.9 7.8 6.3
167

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.0000122 lb a.e./A

Table IͲ4          

GFͲ2685 Dicot Seedling Emergence Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 6.7 5.7 4.6 4.1 3.4 2.8 2.2 1.9 1.5

F2M Air 5.2 3.4 2.8 1.9 1.5 1.0 0.7 0.5 0.5

M2C Air 4.6 2.6 1.7 1.2 0.9 0.5 0.3 0.3 0.2

C2VC Air 4.3 2.2 1.2 0.9 0.5 0.3 0.2 0.2 0.1

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Carrot NOAEC = 0.000558 lb a.e./A

Table IͲ5          

GFͲ2685 Dicot Vegetative Vigor Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 429.1 363.1 297.0 264.0 220.0 176.0 143.0 121.0 99.0

F2M Air 330.1 220.0 176.0 121.0 99.0 66.0 44.0 33.0 33.0

M2C Air 297.0 165.0 110.0 77.0 55.0 33.0 22.0 22.0 11.0

C2VC Air 275.0 143.0 77.0 55.0 33.0 22.0 11.0 10.9 8.8

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Soybean IC05 Ͳ= 0.00000872 lb a.e./A

Table IͲ6          

GFͲ2687 Monocot Seedling Emergence Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 7.0 5.9 4.9 4.3 3.6 2.9 2.3 2.0 1.6

F2M Air 5.4 3.6 2.9 2.0 1.6 1.1 0.7 0.5 0.5

M2C Air 4.9 2.7 1.8 1.3 0.9 0.5 0.4 0.4 0.2

C2VC Air 4.5 2.3 1.3 0.9 0.5 0.4 0.2 0.2 0.1

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.000218 lbs a.e./A

 
168

Table IͲ7          

GFͲ2687 Monocot Vegetative Vigor Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 3.4 2.9 2.4 2.1 1.7 1.4 1.1 1.0 0.8

F2M Air 2.6 1.7 1.4 1.0 0.8 0.5 0.3 0.3 0.3

M2C Air 2.4 1.3 0.9 0.6 0.4 0.3 0.2 0.2 0.1

C2VC Air 2.2 1.1 0.6 0.4 0.3 0.2 0.1 0.1 0.1

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.00111 lbs a.e./A

Table IͲ8          

GFͲ2687 Dicot Seedling Emergence Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 28.1 23.8 19.5 17.3 14.4 11.5 9.4 7.9 6.5

F2M Air 21.6 14.4 11.5 7.9 6.5 4.3 2.9 2.2 2.2

M2C Air 19.5 10.8 7.2 5.0 3.6 2.2 1.4 1.4 0.7

C2VC Air 18.0 9.4 5.0 3.6 2.2 1.4 0.7 0.7 0.6

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Sunflower NOAEC = 0.000133 lbs a.e./A

Table IͲ9          

GFͲ2687 Dicot Vegetative Vigor Listed RQs       

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 39383.9 33324.9 27265.8 24236.3 20196.9 16157.5 13128.0 11108.3 9088.6

F2M Air 30295.3 20196.9 16157.5 11108.3 9088.6 6059.1 4039.4 3029.5 3029.5

M2C Air 27265.8 15147.7 10098.4 7068.9 5049.2 3029.5 2019.7 2019.7 1009.8

C2VC Air 25246.1 13128.0 7068.9 5049.2 3029.5 2019.7 1009.8 1004.8 806.9

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM, Coarse to Very Coarse

(C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Sunflower IC05 = 0.000000095 lbs a.e./A

Table IͲ10

GFͲ2685  Dicot Vegetative Vigor Nonlisted RQs for Aerial Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 367 310 254 226 188 150 122 103 85

F2M Air 282 188 150 103 85 56 38 28 28
169

M2C Air 254 141 94 66 47 28 19 19 9

C2VC Air 235 122 66 47 28 19 9 9 8

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM,

Coarse to Very Coarse (C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Soybean IC25 = 0.0000102 lb a.e./A

Table IͲ11

GFͲ2685  Monocot Vegetative Vigor Nonlisted RQs for Aerial Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 29 25 20 18 15 12 10 8 7

F2M Air 22 15 12 8 7 4 3 2 2

M2C Air 20 11 7 5 4 2 1 1 1

C2VC Air 19 10 5 4 2 1 1 1 1

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM,

Coarse to Very Coarse (C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Onion IC25 = 0.000128 lb a.e./A

Table IͲ12

GFͲ2687  Dicot (Sunflower) Vegetative Vigor Nonlisted RQs for Aerial Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 360 304 249 221 184 148 120 101 83

F2M Air 277 184 148 101 83 55 37 28 28

M2C Air 249 138 92 65 46 28 18 18 9

C2VC Air 231 120 65 46 28 18 9 9 7

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM,

Coarse to Very Coarse (C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Sunflower IC25 = 0.0000104 lb a.e./A

Table IͲ13

GFͲ2687  Dicot (Oilseed) Vegetative Vigor Nonlisted RQs for Aerial Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 9 7 6 5 4 4 3 2 2

F2M Air 7 4 4 2 2 1 1 1 1

M2C Air 6 3 2 2 1 1 0 0 0

C2VC Air 6 3 2 1 1 0 0 0 0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM,

Coarse to Very Coarse (C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Oilseed IC25 = 0.000429 lb a.e./A

 
170

Table IͲ14

GFͲ2687  Monocot Vegetative Vigor Nonlisted RQs for Aerial Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.i./a) 10 25 50 75 100 150 200 250 300

0.00873

VF2F Air 2 2 2 1 1 1 1 1 1

F2M Air 2 1 1 1 1 0 0 0 0

M2C Air 2 1 1 0 0 0 0 0 0

C2VC Air 2 1 0 0 0 0 0 0 0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 137 μM,Fine to Medium (F2M): Dv0.5 = 255 μM, Medium to Coarse (M2C): Dv0.5 = 341 μM,

Coarse to Very Coarse (C2VC): Dv0.5 = 439 μM

Application rate 0.0091 lb a.i./A; Onion IC25 = 0.00154 lb a.e./A

Table IͲ15. Estimated Spray Drift Residues from Ground Spray Applications (Acid Equivalent)

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 0.002302 0.000863

0.0004

8 0.000288 0.000192

9.59EͲ

05

9.59EͲ

05

8.14E

Ͳ05

6.57EͲ

05

Ground

Low Boom 0.000767 0.000288

0.0001

92 9.59EͲ05 8.28EͲ05

5.78EͲ

05

4.46EͲ

05

3.63E

Ͳ05

3.05EͲ

05

F2M/C

Ground

High Boom 0.000384 0.000192

9.59EͲ

05 7.62EͲ05 6.09EͲ05

4.41EͲ

05

3.47EͲ

05

2.86E

Ͳ05

2.43EͲ

05

Ground

Low Boom 0.000288 9.59EͲ05

6.43EͲ

05 4.78EͲ05 3.88EͲ05

2.87EͲ

05

2.3EͲ

05

1.93E

Ͳ05

1.66EͲ

05

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A

Table IͲ16

GFͲ2685 Monocot Seedling Emergence Listed RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 2.1 0.8 0.4 0.3 0.2 0.1 0.1 0.1 0.1

Ground

Low Boom 0.7 0.3 0.2 0.1 0.1 0.1 0.0 0.0 0.0

F2M/C

Ground

High Boom 0.3 0.2 0.1 0.1 0.1 0.0 0.0 0.0 0.0

Ground

Low Boom 0.3 0.1 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.00111 lbs a.e./A
171

Table IͲ17

GFͲ2685 Monocot Vegetative Vigor Listed RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 188.7 70.8 39.3 23.6 15.7 7.9 7.9 6.7 5.4

Ground

Low Boom 62.9 23.6 15.7 7.9 6.8 4.7 3.7 3.0 2.5

F2M/C

Ground

High Boom 31.5 15.7 7.9 6.2 5.0 3.6 2.8 2.3 2.0

Ground

Low Boom 23.6 7.9 5.3 3.9 3.2 2.4 1.9 1.6 1.4

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.0000122 lbs a.e./A

Table IͲ18

GFͲ2685 Dicot Seedling Emergence Listed RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 4.1 1.5 0.9 0.5 0.3 0.2 0.2 0.1 0.1

Ground

Low Boom 1.4 0.5 0.3 0.2 0.1 0.1 0.1 0.1 0.1

F2M/C

Ground

High Boom 0.7 0.3 0.2 0.1 0.1 0.1 0.1 0.1 0.0

Ground

Low Boom 0.5 0.2 0.1 0.1 0.1 0.1 0.0 0.0 0.0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A; Carrot NOAEC = 0.000558 lbs a.e./A

Table IͲ19

GFͲ2685 Dicot Vegetative Vigor Listed RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 264.0 99.0 55.0 33.0 22.0 11.0 11.0 9.3 7.5

Ground

Low Boom 88.0 33.0 22.0 11.0 9.5 6.6 5.1 4.2 3.5

F2M/C

Ground

High Boom 44.0 22.0 11.0 8.7 7.0 5.1 4.0 3.3 2.8

Ground

Low Boom 33.0 11.0 7.4 5.5 4.4 3.3 2.6 2.2 1.9

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A; Soybean IC05 Ͳ= 0.00000872 lbs a.e./A
172

Table IͲ20

GFͲ2687

Monocot Seedling Emergence Listed

RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 4.3 1.6 0.9 0.5 0.4 0.2 0.2 0.2 0.1

Ground

Low Boom 1.4 0.5 0.4 0.2 0.2 0.1 0.1 0.1 0.1

F2M/C

Ground

High Boom 0.7 0.4 0.2 0.1 0.1 0.1 0.1 0.1 0.0

Ground

Low Boom 0.5 0.2 0.1 0.1 0.1 0.1 0.0 0.0 0.0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.000218 lbs a.e./A

Table IͲ21

GFͲ2687 Monocot Vegetative Vigor Listed RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 2.1 0.8 0.4 0.3 0.2 0.1 0.1 0.1 0.1

Ground

Low Boom 0.7 0.3 0.2 0.1 0.1 0.1 0.0 0.0 0.0

F2M/C

Ground

High Boom 0.3 0.2 0.1 0.1 0.1 0.0 0.0 0.0 0.0

Ground

Low Boom 0.3 0.1 0.1 0.0 0.0 0.0 0.0 0.0 0.0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A; Onion NOAEC = 0.00111 lbs a.e./A

Table IͲ22

GFͲ2687 Dicot Seedling Emergence Listed RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 17.3 6.5 3.6 2.2 1.4 0.7 0.7 0.6 0.5

Ground

Low Boom 5.8 2.2 1.4 0.7 0.6 0.4 0.3 0.3 0.2

F2M/C

Ground

High Boom 2.9 1.4 0.7 0.6 0.5 0.3 0.3 0.2 0.2

Ground

Low Boom 2.2 0.7 0.5 0.4 0.3 0.2 0.2 0.1 0.1

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile
173

Application rate 0.0091 lb a.i./A; Sunflower NOAEC = 0.000133 lbs a.e./A

Table IͲ23

GFͲ2687 Dicot Vegetative Vigor Listed RQs

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 24236.3 9088.6 5049.2 3029.5 2019.7 1009.8 1009.8 857.4 691.7

Ground

Low Boom 8078.8 3029.5 2019.7 1009.8 871.5 608.9 469.6 381.7 321.1

F2M/C

Ground

High Boom 4039.4 2019.7 1009.8 801.8 641.3 464.5 365.6 300.9 255.5

Ground

Low Boom 3029.5 1009.8 676.6 502.9 408.0 301.9 242.4 203.0 174.7

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground highboom based on 90th percentile

Application rate 0.0091 lb a.i./A; Sunflower IC05 = 0.000000095 lbs a.e./A

Table IͲ24

GFͲ2685  Dicot Vegetative Vigor Nonlisted RQs for Ground Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 226 85 47 28 19 9 9 8 6

Ground

Low Boom 75 28 19 9 8 6 4 4 3

F2M/C

Ground

High Boom 38 19 9 7 6 4 3 3 2

Ground

Low Boom 28 9 6 5 4 3 2 2 2

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground high boom based on 90th percentile

Application rate 0.0091 lb a.i./A; Soybean IC25 = 0.0000102 lb a.e./A

 
174

Table IͲ25

GFͲ2685  Monocot Vegetative Vigor Nonlisted RQs for Ground Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 18 7 4 2 1 1 1 1 1

Ground

Low Boom 6 2 1 1 1 0 0 0 0

F2M/C

Ground

High Boom 3 1 1 1 0 0 0 0 0

Ground

Low Boom 2 1 1 0 0 0 0 0 0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground high boom based on 90th percentile

Application rate 0.0091 lb a.i./A; Onion IC25 = 0.000128 lb a.e./A

Table IͲ26

GFͲ2687  Dicot (Sunflower) Vegetative Vigor Nonlisted RQs for Ground Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 221 83 46 28 18 9 9 8 6

Ground

Low Boom 74 28 18 9 8 6 4 3 3

F2M/C

Ground

High Boom 37 18 9 7 6 4 3 3 2

Ground

Low Boom 28 9 6 5 4 3 2 2 2

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground high boom based on 90th percentile

Application rate 0.0091 lb a.i./A; Sunflower IC25 = 0.0000104 lb a.e./A

Table IͲ27

GFͲ2687  Dicot (Oilseed) Vegetative Vigor Nonlisted RQs for Ground Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 5 2 1 1 0 0 0 0 0

Ground

Low Boom 2 1 0 0 0 0 0 0 0

F2M/C

Ground

High Boom 1 0 0 0 0 0 0 0 0

Ground

Low Boom 1 0 0 0 0 0 0 0 0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground high boom based on 90th percentile

Application rate 0.0091 lb a.i./A; Oilseed IC25 = 0.000429 lb a.e./A
175

Table IͲ28

GFͲ2687  Monocot Vegetative Vigor Nonlisted RQs for Ground Spray

Application

Rate Droplet

Size

Application

Method

Distance Downwind From Treated Field (feet)

(lb a.e./A) 10 25 50 75 100 150 200 250 300

0.00873

VF2F

Ground

High Boom 1 1 0 0 0 0 0 0 0

Ground

Low Boom 0 0 0 0 0 0 0 0 0

F2M/C

Ground

High Boom 0 0 0 0 0 0 0 0 0

Ground

Low Boom 0 0 0 0 0 0 0 0 0

Very Fine to Fine (VF2F): Avg. Droplet size (Dv0.5) = 175 μM,Fine to Medium/Coarse (F2M/C): Dv0.5 = 342 μM

Ground high boom based on 90th percentile

Application rate 0.0091 lb a.i./A; Monocot IC25 = 0.00154 lb a.e./A