4UNITED ST ATES ENVIRONMENT AL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

MEMORANDUM Date: March 22, 2016 

Subject: Preliminary Environmental Fate and Ecological Risk Assessment for the 

Registration Review of Ethalfluralin 

To: 

From: 

PC Code: 113 1 OJ 

DP Barcodes: D429845 

Kelly Ballard, Chemical Review Manager 

Melissa Grable, Team Leader 

Neil Anderson, Chief 

Risk Management and Implementation Branch I 

Pesticide Re-evaluation Division (7505P) 

/_ 

Geoffrey Sinclair, Ph.D., Biol~ ~ 

E

Michael 

nvironmental 

Barrett

Risk 

, Ph.D.

Branch 

, Chem

5 

~ 

Environmental Fate and Effects Division (7507P) 

Reviewed By: Hannah Yingling, Biologist 

Mohammed Ruhman, Ph.D., Senior Agronomist 

Environmental Risk Branch 5 

Environmental Fate and Effects Division (7507P) 

Approved: Mah Shamim, Ph.D., Branch Chief 

Environmental Risk Branch 5 

Environmental Fate and Effects Division (750 P) 

Office of Pesticide Programs 

The Environmental Fate and Effects Division (EFED) has completed the ecological effects and 

environmental fate preliminary risk assessment conducted as part of the registration review of 

the herbicide ethalfluralin. An evaluation of ecological risk to aquatic and terrestrial organisms 

as a result of the use of ethalfluralin is summarized in the Executive Summary and the Risk 

Characterization sections of the attached document. A separate document containing a 

preliminary problem formulation was prepared for ethalfluralin (DP Barcode D382172) in March 

2011 and was released for public comment. 
2

Preliminary Environmental Fate and Ecological Risk 

Assessment for the Registration Review of

Ethalfluralin

Prepared by:

Geoffrey Sinclair, Ph.D., Biologist

Michael Barrett, Ph.D., Environmental Scientist

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Mah Shamim, Ph.D., Branch Chief
3

Table of Contents

1. Executive Summary................................................................................................................ 7

2. Mechanism of Action.............................................................................................................. 9

3. Use Characterization............................................................................................................... 9

3.1 Labelled Use..................................................................................................................... 9

3.2 Usage.............................................................................................................................. 15

4. Exposure Characterization.................................................................................................... 17

4.1 Environmental Fate and Transport Summary ................................................................ 17

4.2 Exposure Pathways ........................................................................................................ 22

4.3 Aquatic Exposure Analysis............................................................................................ 24

4.4 Clean Water Act............................................................................................................. 28

4.5 Terrestrial Exposure Analysis........................................................................................ 28

5 Ecological Effects Characterization...................................................................................... 37

5.5 Aquatic Effects Summary .............................................................................................. 38

5.6 Terrestrial Effects Summary .......................................................................................... 41

5.7 ECOTOX Open Literature ............................................................................................. 45

5.8 Review of Incident Data................................................................................................. 45

6 Risk Characterization............................................................................................................ 54

6.5 Risk Estimation .............................................................................................................. 54

6.6 Non-target Aquatic Animals and Plants......................................................................... 55

6.3 Non-target Terrestrial Animals...................................................................................... 58

7 Risk Description.................................................................................................................... 64

7.1 Risk to Non-Target Aquatic Organisms......................................................................... 64

7.2 Risk to Non-Target Terrestrial Organisms..................................................................... 67

8 Uncertainties, Assumptions, and Limitations....................................................................... 72

9 Endocrine Disruptor Screening Program.............................................................................. 76

10 Federally Threatened and Endangered (Listed) Species of Concern.................................... 76

11 Conclusions........................................................................................................................... 77

12 References............................................................................................................................. 85

Appendix A. Environmental Fate and Ecological Effects Data for Ethalfluralin........................ 87

Appendix B. Ethafluralin ECO Effects Bibliography.................................................................. 93

Appendix C. Aquatic Exposure Modeling Inputs and Results.................................................. 103

Appendix D. Sample TREX Files.............................................................................................. 122

Appendix E. Sample TerrPlant Files ......................................................................................... 124

Appendix F. Sample KABAM Files.......................................................................................... 127

Appendix G. Risk Quotient Method .......................................................................................... 130

Appendix H. Environmental Degradates of Ethalfluralin........................................................... 132
4

Table of Tables

Table 1. Summary of ethalfluralin product labels registration numbers. .................................... 10

Table 2. Summary of ethalfluralin application rates and methods by crop site............................ 12

Table 3. Screening Level Estimates of Agricultural Uses of Ethalfluralin for 2004-2013.......... 15

Table 4. Summary of Physicochemical Properties of Ethalfluralin............................................. 20

Table 5. Ethalfluralin physicochemical and fate property inputs for the SWCC model. ............ 24

Table 6. SWCC crop scenario and application-related input parameter values for ethalfluralin 

aquatic exposure estimation.......................................................................................................... 25

Table 7. SWCC estimated upper-bound peak, 21-day and 60-day concentrations in the surface 

water column and sediment for ethalfluralin at the highest application rate for proposed crop 

uses................................................................................................................................................ 26

Table 8. Input parameters for endpoints used in T-REX v 1.2.5 to determine terrestrial RQs. .. 29

Table 9. Avian TREX upper-bound dose-based EECs (mg/kg)................................................... 30

Table 10. Mammalian TREX dose-based EECs (mg/kg)............................................................. 31

Table 11. T-REX dietary based EECs......................................................................................... 31

Table 12. Estimated LD50/ft2 (in mg active ingredient (a.i.) per square foot) from granular 

applications of ethalfluralin across uses. ...................................................................................... 32

Table 13. TerrPlant EECs (lbs. a.i./A) for ethalfluralin exposure to terrestrial and wetland plants 

resulting from runoff and spray drift. ........................................................................................... 33

Table 14. Ethalfluralin contact and oral estimated exposure dose concentrations to honeybees. 36

Table 15. Input parameters for KABAM model.......................................................................... 36

Table 16. Estimated concentrations of ethalfluralin in ecosystem components. .......................... 37

Table 17. Summary of Acute and Chronic Toxicity Data for Aquatic Taxa Exposed to 

Ethalfluralin. ................................................................................................................................. 39

Table 18. Summary of Toxicity for Terrestrial Taxa Exposed to Ethalfluralin............................ 42

Table 19. Summary of Ecological Incidents as found in EIIS from the Usage of Ethalfluralin 

(Note: In every incident, the taxa affected were terrestrial plants)............................................... 45

Table 20. Risk presumptions for terrestrial animals based on risk quotients (RQ) and levels of 

concern (LOC). ............................................................................................................................. 55

Table 21. Acute RQs for fish and aquatic invertebrates exposed to ethalfluralin. ....................... 56

Table 22. Chronic RQs for fish and aquatic invertebrates exposed to ethalfluralin.................... 56

Table 23. Porewater-based RQs for freshwater sediment-dwelling invertebrates...................... 57

Table 24. Organic carbon normalized sediment based RQs for freshwater sediment dwelling 

invertebrates.................................................................................................................................. 57

Table 25. RQs for non-vascular and vascular aquatic plants exposed to ethalfluralin. ................ 58

Table 26. Chronic dose-based RQs for mammals exposed to proposed spray uses of ethalfluralin.

....................................................................................................................................................... 59

Table 27. Monocot RQs from applications of ethalfluralin in the modeled scenarios of Runoff 

and Spray Drift in Dry areas, Runoff and Spray Drift in Semi-Aquatic Areas, and Spray Drift 

only. .............................................................................................................................................. 60

Table 28. Dicot RQs from applications of ethalfluralin in the modeled scenarios of Runoff and 

Spray Drift in Dry areas, Runoff and Spray Drift in Semi-Aquatic Areas, and Spray Drift only.62
5

Table 29. Contact RQs for bees that result from applications of ethalfluralin. ............................ 64

Table 30. Buffer distances for aquatic taxa using very fine to fine droplet sizes......................... 65

Table 31. Buffer distances for aquatic taxa using fine to medium coarse droplet sizes............... 65

Table 32. Buffer distances from spray applications with very fine to fine droplet sizes.............. 67

Table 33. Buffer distances from spray applications with fine to medium/coarse droplet sizes.... 67

Table 34. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive 

monocot species for applications with very fine to fine droplet size spectrum (ground 

applications).................................................................................................................................. 70

Table 35. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive dicot 

species for applications with very fine to fine droplet size spectrum (ground applications)........ 70

Table 36. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive 

monocot species for applications with fine to medium coarse droplet sizes (ground applications).

....................................................................................................................................................... 71

Table 37. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive 

dicot species for applications with fine to medium coarse droplet sizes (ground applications)... 71

Table 38. Summary of adverse impacts for aquatic organisms expected from the existing uses of 

ethalfluralin................................................................................................................................... 79

Table 39. Summary of adverse impacts for terrestrial organisms expected from the existing uses 

of ethalfluralin............................................................................................................................... 81
6

Table of Figures

Figure 1. USGS estimate agricultural use for ethalfluralin in the US 2012 map (top figure) and 

1992-2013 national summary (bottom figure).............................................................................. 17
7

1. Executive Summary

Scope and Rationale for Registration Review Risk Assessment

This document contains the environmental fate and ecological risk assessment for the registered 

uses of the chemical ethalfluralin. Ethalfluralin is a member of the dinitroaniline class of 

herbicides that inhibits the formation of the cell wall in plants (both aquatic and terrestrial) and 

by initiating desiccation of the xylem and phloem systems in plants. 

Ethalfluralin Current Registered Uses

Ethalfluralin is soil incorporated (mechanically or by wetting in) and used on alfalfa, clover, dill, 

bean (dry), cucurbits, lentils, mustard, oilseed (sunflower, jojoba etc.), oilseed (crambe, 

rapeseed), oilseed sunflower, peanuts, peas (dry), potatoes and soybeans. Both flowable and 

granular formulations are registered for various crops. Also depending on the crop site, 

ethalfluralin may be applied pre-emergence, post-emergence, or in the fall during fallow periods. 

The maximum label rates for the various crop sites range from about 0.75 to 1.69 pounds of 

active ingredient (a.i.) per acre.

Environmental Fate and Exposure Summary

Ethalfluralin residues have the ability to reach nearby water bodies in sediment borne in runoff 

or in a dissolved state via spray drift or runoff. Exposure modeling indicates that under most use 

conditions aquatic exposure is primarily from spray drift at the time of application and that 

transport via runoff is primarily (but not exclusively) in soil-bound residues (erosion) rather than 

dissolved phase. This is consistent with ethalfluralin’s relatively high soil organic carbon –

water partition coefficient (Kfoc range of 3967-8083 mL/g).

The environmental persistence of ethalfluralin varies significantly with the different

transformation pathways that are available after application. Most of the chemical that reaches

the soil system will be transformed within 2 months based on the aerobic soil biotransformation 

with half-lives ranging from 17 to 46 days. Ethalfluralin transformation in soil sediment is 

relatively rapid with an anaerobic aquatic half-life of 1.6 days (single test). If sunlight is present 

ethalfluralin transformation can be quite rapid (aquatic photodegradation half-life value of 6.3 

hours). This may greatly accelerate the degradation of any dissolved residues present in clear 

surface waters but the effect of photolysis on most aquatic systems is not expected to be 

significant due to turbidity and light attenuation in most water bodies. Volatilization can be a 

significant mechanism of dissipation (vapor pressure of 8.2 x 10-5 mm Hg at 25°C is indicative 

of this) and degradation in the atmosphere within a few hours or days is predicted. 

Ecological Effects Summary and Risk Conclusions
8

When estimates of ethalfluralin exposure in terrestrial and aquatic environments are compared to 

the available ecotoxicity data, the results indicate a potential for risk above the level of concern 

to both aquatic and terrestrial taxa from proposed uses of ethalfluralin. Aquatic taxa were 

determined to be at risk from both acute and chronic exposure while terrestrial animals were at 

risk from chronical exposure.

Ethalfluralin is very highly toxic to aquatic animals on an acute exposure basis. In general, risk 

quotients (RQ) for aquatic organisms are calculated considering estimated exposure 

concentration (EEC) in the surface water column for each crop. Acute risk concerns exist for 

federally listed threatened/endangered (hereafter referred to as “listed”) freshwater fish and 

invertebrates (RQs 0.06 – 0.39) and estuarine / marine fish and invertebrates at the highest 

application rates (RQs 0.05-0.07). Chronic risk concerns exist for listed and non-listed 

freshwater fish from multiple application rates (RQs 1.0 to 3.4) and to estuarine/marine fish at 

the highest application rate (RQ = 1.13) but not to aquatic invertebrates. Sediment-dwelling 

freshwater invertebrates were also determined to be at risk from chronic exposure to residues in

sediment (RQs 1.3-4.0). Risk was identified to non-listed aquatic vascular plants only at the 

highest application rates (RQ = 1.7). Risk to listed vascular plants was identified for several 

application rates ranging from 1 to 1.7 lbs ai/A with RQs from 3 to 10.4. Risk to listed nonvascular plants was only identified at the highest application rate of 1.7 lbs ai/A (RQ = 1.1). 

For terrestrial wildlife, ethalfluralin is practically non-toxic to birds, mammals, and terrestrial 

insects on an acute exposure basis. Ethalfluralin is classified as practically non-toxic to honey 

bee adults on an acute contact exposure basis. How ethalfluralin impacts of adults bees from 

chronic exposure or larval bees from acute or chronic exposure remain uncertain. Additional 

studies addressing the pollinator data gaps for chronic adult exposure and acute and chronic 

larval exposure would help reduce this uncertainty.

No risk is identified for either non-listed or listed birds, reptiles, or terrestrial-phase amphibians,

from acute or chronic exposure to ethalfluralin. Chronic risk to mammals is identified for uses 

involving spray applications (RQs range from 0.01 to 3.3). RQs for small- and medium-sized 

mammals (15 g and 35 g mammals respectively) exceed the chronic risk LOC of 1.0 for those 

animals foraging on short grass, tall grass, broadleaf plants following uses on alfalfa, cucurbits, 

potatoes and sunflower with application rates at 1 to 1.69 lbs a.i./A. Modelling suggests there 

may be potential chronic risk to mammals from consuming fish containing residues that have 

accumulated through trophic transfer with one LOC exceedance at the highest application rate 

(RQ 1.1). 

Risk to terrestrial plants was identified for every use of ethalfluralin (non-listed and listed RQs 

ranging between <0.1 – 131), and both runoff and spray drift processes contribute to the overall 

risk. 
9

Data gaps to improve understanding of ecological effects

The ecological database for ethalfluralin has a number of outstanding data gaps as follows:

1. Whole sediment toxicity testing with an estuarine/marine sediment dwelling invertebrate

(Guideline 850.1735)

2. Tier 1 Acute oral toxicity to adult honeybees (Non-guideline; OECD 213)

3. Tier 1 Acute oral toxicity to larval honeybees (Non-guideline; OECD 237)

4. Tier 1 Chronic oral toxicity to adult honey bees (Non-guideline)

5. Tier 1 Chronic oral toxicity to larval honey bees (Non-guideline)

6. Tier 2 Pollinator feeding/semi-field study - The need for these studies is contingent upon 

the results of lower tier bee studies (Non-guideline)

7. Tier 2 Pollen and nectar residue studies – The need for these studies is contingent upon 

the results of lower tier bee studies (Non-guideline)

8. Tier 2 Field testing for pollinators – The need for field testing is contingent upon the 

results of lower tier bee studies (850.3040)

2. Mechanism of Action

Ethalfluralin is a member of the dinitroaniline class of herbicides which are selective herbicides 

mainly used in control of certain annual and broadleaf weeds. Ethalfluralin functions by 

inhibiting the formation of the cell wall in plants (both aquatic and terrestrial) and by initiating 

desiccation of the xylem and phloem systems in plants. Specifically, they inhibit microtubule 

synthesis necessary in the formation of cell walls, but also vital for mitosis, as microtubules 

facilitate the process by ensuring correct positioning and orientation of the mitotic spindle 

apparatus. Microtubules are also involved in the determination of cell division site based on the 

geometry and polarity of the cells. Dinitroaniline herbicides are absorbed somewhat by plant 

root systems, and to a greater extent by young seedling shoot organs such as the hypocotyl or 

coleoptile. Little or no translocation of these herbicides occurs in plants (Parka and Sopa, 1977).

Additionally, ethalfluralin has a registered label with another active ingredient, clomazone. The 

formulation is used for control of broadleaf weeds in melons, pumpkins, squash, and 

watermelons. Clomazone acts by inhibiting carotenoid synthesis so that affecting plants are 

devoid of pigment, and therefore cannot photosynthesize.

3. Use Characterization

3.1 Labelled Use
10

Current labels (Table 1) allow the usage of ethalfluralin on alfalfa, clover, dill, bean (dry), 

cucurbits, lentils, mustard, oilseed (sunflower, jojoba etc), oilseed (crambe, rapeseed), oilseed 

sunflower, peanuts, peas (dry), potatoes and soybeans. Depending on the crop, ethalfluralin may 

be applied pre-emergent, post-emergent, or in the fall prior to a spring planting. More details on 

ethalfluralin maximum application rates and application methods are presented in Table 2. The 

maximum application rates are specified as a single or crop-cycle basis. Liquid formulations of 

ethalfluralin are applied as a band/broadcast surface spray with ground equipment or via

chemigation applied through sprinklers. However, the granular formulation is applied to the soil 

surface with mechanical incorporation or incorporation through rainfall and/or sprinklers. 

Although not explicit on labels, it appears that applications are only made once per year / 

growing season (September 2015 correspondence from Office of Pesticide Programs’ Biological 

and Economic Analysis Division; BEAD). 

Table 1. Summary of ethalfluralin product labels registration numbers.

Registrant Reg. No. 1 Use Sites and SLN ID, if applicable. 1

Dow AgroScience 

-FIFRA Section 3

62719-184 (Granular)

62719-188 (EC)

+ SLNs (see below)

1. Dry beans

2. Dry peas

3. Oilseed – Crambe, flax seed, rapeseed, etc.

4. Oilseed – Sunflower, etc.

5. Oilseed – Safflower

6. Peanut

7. Alfalfa, clover (SLNs= Special Local Needs 

Labels)

8. Lentils (SLNs)

Dow AgroScience

Special Local Needs

62719-184 (Granular)

SLNs

SLN - MT-06-0003

1. Lentils

SLN - ND-090004

1. Yellow Mustard

SLN - ND-050010

1. Lentils

Dow AgroScience

Special Local Needs

62719-188 (EC)

SLNs:

SLN - NV-950001 +

SLN - ID-950020 +

SLN - MT-01-0002 +

SLN - WY-030005 +

SLN - OR-940037 +

SLN - WA-940018 

1. Alfalfa for seed
11

Loveland

FIFRA Section 3

34704-610 (EC)

34704-836 (EC)

OR-120002 SLN

WA-0900l3 SLN

1. Cucurbits group (Cucumbers, etc.)

Loveland

Special Local Needs

34704-610 (EC) OR-120002 SLN

WA-0900l3 SLN

1. Dill 

1 EC= Emusifiable concentrate; SLN=special local needs
12

Table 2. Summary of ethalfluralin application rates and methods by crop site. 

Crop1 Application Timing

Single Application Rates 

(lbs a.i./A2

Application Codes*

Soil Type Specific 

Rates

Label Information

Maximum Range

Variation max . rate 

with soil type, if 

applicable3

Reg. No.

Alfalfa (ID, NV, WA 

& WY, MT, OR)

Pre-emergence 1.69 1.51 - 1.69

EC-1 (ID,MT); EC-2 

(All); EC-3 (OR)

C = 1.7, M = 1.5, F = 

1.3

62719-188 (EC)

24c registrations

Germination 1.69 1.69 EC-2 (NV)

Established plantings 1.52 1.36 - 1.52

EC-2 (WA, WY); EC-3

(WA)

Late tillering 1.51 1.51 EC-1 (NV)

Beans (dry)

Pre-plant

1.69 1.13 - 1.69 EC-2, Gran-F & Gran-2 F = 1.7, M = 1.5, C = 

1.3

62719-184 and -188

Pre-emergence 1.69 1.13 - 1.69 EC-3

Fall 1.70 1.13 - 1.69 Gran-F

Clover (WY) Established plantings 1.50 1.13 – 1.50 EC-2 (WY)

NA 62719-188 (EC) SLN 

WY-30005

Cucurbits 

(Cucumber “CU”, 

Melons, Pumpkin & 

Squash “SQ” 

summer/ winter)

Pre-plant (CU, PM), At 

seeding (All), Preemergence (All) & Postemergence (PM, SQ)

1.70 1.13 – 1.70

0.40- 1.20

(w 

clomazone)

EC-1 F = 1.7, M = 1.5, C = 

1.1

F = 1.2, M = 0.8, C = 

0.6

34704-610

34704-836

Dill (OR, WA)

Pre-plant & Post-plant

1.13 0.56 - 1.13 EC-1 (OR, WA) NA 34704-610 SLN's

OR-120002

WA--090013

Lentils (MT & ND)

Stubble (MT)

Stubble (ND)

0.750

0.950

0.750

0.55 – 0.75

Gran-2 (MT & ND) F = NS, M = 0.75, C = 

0.75

62719-184

24c - MT-06-0003

24c - ND-090004

24c - ND-050010
13

Crop1 Application Timing

Single Application Rates 

(lbs a.i./A2

Application Codes*

Soil Type Specific 

Rates

Label Information

Maximum Range

Variation max . rate 

with soil type, if 

applicable3

Reg. No.

Mustard (ND) Stubble 0.95 0.550 - 0.950 Gran-2 (ND) 62719-184

24c -ND-09004

Oilseed – Sunflower, 

Jojoba, etc. group3 Spring (any time after Jan. 

1), fall

1.7 0.550 – 1.70 Gran-2 & Gran-F

EC-3

Gran-F

F = 1.7, M = 1.5, C = 

1.3

62719-184 and -188

Oilseed – Crambe, 

Rapeseed (canola), 

etc. group4

Except CA.

Spring before planting or 

fall 0.95

0.550 - 0.950

EC-2, Gran-2 & Gran-F, 

Except CA

F = 0.95, M = 0.75, C 

= 0.55

62719-184 and -188

Oilseed - Safflower Pre-plant 1.15 0.550 - 1.15 Gran-2 & Gran-F

F = 1.15, M = 0.95, C 

= 0.75

62719-184 and -188

Peanuts Pre-plant 1.15 0.563 - 1.13 EC-2, Gran-F & Gran-2 F = 1.13, M = 0..938, 

C = 0.750

62719-184 and -188

Peas (dry)

Except CA.

Pre-plant 0.750 0.750 EC-2, Gran-F & Gran-2

Max. rate does not 

vary.

62719-184 and -188

Fall 0.750 0.750 Gran-F

Potatoes ** After planting but prior to 

emergence 1.028 0.500- 1.000 EC-2 & EC-3

F = 1.00, M = 1.00, C 

= 0.75

62719-188 only

Soybeans Pre-plant 1.31 0.56- 1.31 Gran-2 & Gran-F

F = 1.31, M = 1.13, C 

= 0.75

62719-184 and -188

Fall 1.31 0.56 - 1.31 Gran-F

F = 1.31, M = 1.13, C 

= 0.75

62719-184 and -188

* Application Codes:

EC: Applications with an emulsifiable concentrate (EC) formulation type (On Dow labels the EC is identified as an “HFP”, this appears to refer to the use of 

hexafluoropropylene copolymers in the formulation).

EC-1: Band/broadcast (not incorporated) applied by low pressure ground sprayer
14

Crop1 Application Timing

Single Application Rates 

(lbs a.i./A2

Application Codes*

Soil Type Specific 

Rates

Label Information

Maximum Range

Variation max . rate 

with soil type, if 

applicable3

Reg. No.

EC-2: 3" Incorporated applied by spreader/incorporation equipment

Gran-F: Impregnated with dry fertilizers (3” Incorporated) applied by spreader/incorporation equipment 

EC-3: Chemigation applied through sprinklers

Gran-2= Granular formulation: requires 2 separate incorporation steps, the first incorporation needs to occur within 48 hours after application. The label states to use 

incorporation equipment capable of thoroughly and uniformly mixing Sonalan® 10G into the top 2 to 3 inches of the final seedbed. Optional Methods of 

incorporation for soybeans, dry beans and peanuts on medium and coarse textured soils. Sonalan® l0G may be applied as a surface application and incorporated by 

rainfall or sprinkler irrigation.

** Potatoes: for use in the States of AZ, CO, NE (West of Rt. 281), 10, KS (West of Rt. 281), MT, ND (West of Rt. 281), NV, NM, OK (West of Rt. 281/283), OR, 

SD (West of Rt. 281), TX (West of Rt. 281 and Northwest of Rt. 377), UT, WA and WY.

NA = Not applicable (no variation of rates with soil texture classification specified).

FOOTNOTES:

 If local need or geographically restricted label- States / regions where usage is currently permitted are listed in parenthesis or in a footnote.

2 Maximum crop cycle / seasonal / annual application rates are generally not explicitly specified on the product labels. A maximum number of applications (1 in all 

cases where specified) per season is sporadically specified with the uses on cucumber, melon, pumpkin, safflower, winter and summer squash. With the granular 

formulation the following limits are specified:

Safflower = 1.15 lb ai / year.

All other crops on Granular label (canola, crambe, dry beans, dry peas, peanuts, soybeans, and sunflowers) = 1.4 lb ai / year. 

Presumably (but not explicitly specified on the label) in situations where a higher single application rate is specified (e.g., for dry beans and sunflowers) this takes 

precedence over the 1.4 lb ai / year limitation. 3 C = coarse textured soils, M = medium textured soils, and F = fine textured soils

GENERAL NOTES:

If local need or geographically restricted label- States / regions where usage is currently permitted are listed in parenthesis or in a footnote.

Maximum crop cycle / seasonal / annual application rates are generally not explicitly specified on the product labels. A maximum number of applications (1 in all 

cases where specified) per season is sporadically specified with the uses on cucumber, melon, pumpkin, safflower, winter and summer squash. With the granular 

formulation the following limits are specified:

Safflower = 1.15 lb ai / year.

All other crops on Granular label (canola, crambe, dry beans, dry peas, peanuts, soybeans, and sunflowers) = 1.4 lb ai / year. 

Presumably (but not explicitly specified on the label) in situations where a higher single application rate is specified (e.g., for dry beans and sunflowers) this takes 

precedence over the 1.4 lb ai / year limitation. 
15

3.2 Usage

In recent years, the use sites with ten percent or more of the crop treated (estimated) have been: 

cucumbers, pumpkins, squash, dry beans/peas, peanuts, watermelons, and sunflowers according 

to the screening-level use assessment (SLUA) provided by BEAD (see Table 3).The largest uses 

in terms of the estimated annual acres treated have been dry beans/peas followed by peanuts and 

sunflowers. 

Overall, the usage of ethalfluralin has been declining since 2002, according to estimates provided 

by the U.S. Geological Survey (see Figure 1). The most recent year estimate (using the “EPest 

High” method the USGS considers the most conservative for calculating usage) in 2013 was 

about 1.5 million pounds applied nationally.

Table 3. Screening Level Estimates of Agricultural Uses of 

Ethalfluralin for 2004-2013.

Crops

Average Annual 

Lbs. A.I. Applied

Percent Crop Treated

Average Annual Maximum

Alfalfa 9,000 <1 <2.5

Beans, Green+ 6,000 5 25

Cabbage+ <500 <1 <2.5

Canola 4,000 <2.5 <2.5

Cantaloupes 5,000 5 15

Cucumbers 50,000 50 65

Dry Beans/Peas 600,000 25 40

Peanuts 200,000 25 40

Peas, Green+ <500 <1 <2.5

Peppers+ <500 <1 <2.5

Potatoes 2,000 <1 <2.5

Pumpkins 20,000 30 40

Soybeans 40,000 <1 <2.5

Squash 10,000 30 35

Sunflowers 200,000 10 20

Watermelons 20,000 20 35

TOTAL ca. 1,168, 000

(BEAD estimates, 6/11/2015; based on data sources reflecting usage 

over the period 2004 - 2013)
16
17

“Use by Year and Crop” bar chart note: Order of crops in bars from top to bottom is: Other crops, pasture and hay, 

alfalfa, orchards and grapes, rice, vegetables and fruit, cotton, wheat, soybeans, and corn.

Source: 

https://water.usgs.gov/nawqa/pnsp/usage/maps/index.php. 

Specific url:

https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2012&map=ETHALFLURALIN&hilo=H

Figure 1. USGS estimate agricultural use for ethalfluralin in the US 2012 map (top figure) 

and 1992-2013 national summary (bottom figure).

4. Exposure Characterization

4.1 Environmental Fate and Transport Summary

This environmental fate and transport section addresses the environmental fate and transport 

properties of parent ethalfluralin. This assessment does not consider the environmental fate and 

transport properties of any of the numerous minor degradates formed from ethalfluralin 

degradation in the soil through microbial activity (further discussed below). 

Ethalfluralin can be characterized as having low to moderate persistence varying with the 

environmental conditions and dominant transformation pathways pertaining to those conditions. 

The environmental persistence varies from hours to months depending upon the transformation 

pathways that are available after application (always incorporated for all uses). Most of the 

chemical in the soil system will be transformed within 2 months based on the aerobic soil 
18

biotransformation with half-lives ranging from 17 to 46 days. Ethalfluralin transformation is 

relatively rapid with an anaerobic aquatic half-life of 1.6 days (single test). If sunlight is present 

ethalfluralin transformation can be quite rapid (aquatic photodegradation half-life value of 6.3 

hours). This may greatly accelerate the degradation of any dissolved residues present in clear 

surface waters but the effect of photolysis on most aquatic systems is not expected to be 

significant due to turbidity and light attenuation in most water bodies. Ethalfluralin is practically 

insoluble in water and is strongly bound to soil and sediment so the extent to which it is 

dissolved in the water column and susceptible to photolysis is likely limited. 

Ethalfluralin has a vapor pressure of 8.2 x 10-5 mm Hg at 25°C which is indicative of a potential 

for significant dissipation in the environment by volatilization (Kennedy and Talbert, 1977). 

1977).Vapor-phase ethalfluralin is expected to degrade in the atmosphere by reaction with photochemically produced hydroxyl radicals and ozone molecules. The half-life for this reaction in air 

with hydroxyl radicals is estimated to be 6 hours and the half-life for this reaction with ozone is 

estimated as 23 hours.1 With the EPI (Estimation Programs Interface) Suite2 AOPWIN function 

the hydroxyl radical reaction half-life was estimated to be 1.9 hours and ozone reaction half-life 

was estimated to be 22.9 hours. Therefore, chronic atmospheric exposure, or transport are 

precluded, and any concerns would likely be restricted to acute exposures. Ethalfluralin’s 

potential for volatilization may be reduced significantly because it adsorbs strongly to soils as 

well as to suspended solids, particulate, sediment, and organic matter in the water column.

Ethalfluralin will be mostly immobile in soil and bound to sediment in both terrestrial and 

aquatic environments (Freundlich Kads values of 12 to 97 mg/L, Kfoc values of 3957 to 8361 

ml/g). While ethalfluralin is not expected to contaminate ground water, it may reach ground 

water through its binding capacity to soil and soil particles and through erosion (i.e., runoff of 

sediment-bound residues), and a very limited number of low level detections have been reported

in ground water where ethalfluralin was included as an analyte. In surface waters, ethalfluralin is 

likely to be quickly and predominantly partitioned to sediments, however no monitoring data are

available for sediments. Ethalfluralin would be likely though be quickly degraded to less toxic 

compounds which would be tightly bound to sediment colloids and organic material.

Ethalfluralin is stable to hydrolysis at pH values of 3, 6, and 9. Ethalfluralin, based on laboratory 

studies, is expected to be largely bound to soil particles and subject to aerobic or anaerobic 

metabolism. Field dissipation half-lives ranged from 23 to 51 days and are similar to the 

laboratory metabolism half-lives in aerobic soil. No degradates were analyzed for in any of these 

studies since there were no major degradates in the environmental fate studies. 

Adsorption is the highest in soils that are very rich in organic matter or clay content. Higher 

application rates are recommended on the product labels for these types of soils are consistent 

with the more rapid loss of available active ethalfluralin parent.

 1 See MRID 00094810 and http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+7545

(accessed on 1/10/2011).

2 Version 4.0, available at: http://www.epa.gov/oppt/exposure/pubs/episuitedl.htm .
19

Both the aerobic and anaerobic degradation of ethalfluralin is complex with multiple pathways 

and products, none of which have been found to substantially accumulate in the environment. 

Several minor (all were <10% of applied, usually much less) metabolites in soil have been 

detected in the laboratory studies3. Ethalfluralin is very similar structurally to trifluralin (a,a,atrifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) with the only difference in the molecules being in 

the nature of the alkyl substitutions of the amine moiety (N-(2-melhyl-2-propenyl) for 

ethalfluralin versus N,N-dipropyl for trifluralin. For the similar pesticide trifluralin, a very 

complex degradation pattern has been established involving numerous minor degradation 

products4.

See Appendix H for a summary of the ethalfluralin degradation pathway in aerobic and 

anaerobic soil). For example, in an aerobic metabolism study in three test soils ethalfluralin 

degraded almost entirely to a multitude of minor degradation products in three test soils (MRID 

48915601; study classified as supplemental). The most significant degradates detected in terms 

of the maximum percent of applied were:

M2 (ET-20) = 2,6-Dinitro-4-(trifluoromethyl)phenol (Up to 5.2% of applied ethalfluralin)

M5 (ET-15M) = 2-Methyl-7-nitro-5-(trifluoromethyl)benzimidazole (Up to 6.5% of applied 

ethalfluralin)

Unextracted residues increased over time to 51 to 65% in the 3 test soils, but the extraction 

scheme was sufficient to demonstrate that these residues were readily available and the 

corresponding accumulation of degradation products was indicative of extensive transformation 

of parent trifluralin with the accumulation of such residues. 

ET-4 = N2-Ethyl-N2-(2-methyl-2-propenyl)-3-nitro-5- (trifluoromethyl)-1,2-benzenediamine

ET-7 = N2

-Ethyl-N2-(2-methyl-2-propenyl-5-(trifluoromethyl)-1,2,3-benzenetriamine

In an anaerobic soil metabolism study (MRID 42930102) two major metabolites of ethalfluralin, 

formed by the reduction of one nitro group (ET -4) or both nitro groups (ET-7), were identified 

during the study: ET-4 reached a maximum of 31.0% of the applied radiocarbon or 0.04 ppm in 

the day 0 samples, but was not detectable after day 1. ET-7 reached a maximum of 32.0% of the 

applied radiocarbon at Day 1, but was not detectable after day 1. These are not considered to be 

major metabolites because they form almost instantly under anaerobic conditions and further 

transformation takes place rapidly. Multiple strong extraction systems failed to remove most of 

the applied radioactivity with time – at study conclusion after 6 months of incubation 86 to 94% 

of the applied radioactivity remained bound to the soil.

Ethalfluralin has some characteristics which indicate it should be considered for bioaccumulation 

potential, such as a relatively high log octanol-water partition coefficient (log Kow) of 5.11 and 

significant bioaccumulation in fish; however, the compound is also subject to relatively rapid 

depuration half-life of 3 days (Table 3). In a study with radio-labeled ethalfluralin, bluegill 

 3 In the aerobic metabolism study all degradates were present at 3% or less during the entire course of the 9-month 

study. See Appendix for structures of the metabolites and a degradation pathway proposed by the registrant. 

4 Grover, R.; Wolt, J.D.; Cessna, A.J; Schiefer H.B. 1997. Environmental fate of trifluralin. Rev Environ Contam 

Toxicol. 153:1-64.
20

sunfish (Lepomis macrochirus) had measured bioconcentration factors (BCF) ranging from 1040 

to 1560X; however, when exposure stopped, half of the compound was depurated after 3 days

(MRID 41994902). 

In the Environmental Fate and Ecological Risk Assessment Problem Formulation in Support of 

Registration Review of Ethalfluralin (DP Barcode D382172, 3/14/2011) and the Reregistration 

Eligibility Decision (RED) document (EPA 738-R-95-001, March 1995) the only residue of 

concern in animals and plants was determined to be the parent ethalfluralin. However, the RED 

recommended an additional study of cucurbits to verify whether the parent alone should be 

considered in setting tolerances. 

Table 4. Summary of Physicochemical Properties of Ethalfluralin.

Parameter Value and Unit Source

Chemical Structure

Chemical Name N-ethyl-∀∀∀-trifluoro-N-(2-methylallyl)-2,6-dinitro-p-toluidine

OR

N-ethyl-N-(2-melhyl-2-propenyl)-2,6-dinitro4-{trifluoromethyl)benzenamine .

Smiles Code CCN(CC(=C)C)C1=C(C=C(C=C1[N+](=O)[O-

])C(F)(F)F)[N+](=O)[O-]

CAS Number 5528-68-6

PC Code 113101

Empirical Formula C13H14F3N3O4 Product Chemistry data

Molecular Weight 333.27 g Product Chemistry data

Appearance crystalline Product Chemistry data

Color Yellow Product Chemistry data

Odor faint amine-odor Product Chemistry data

Melting Point 57 – 59 o

C Product Chemistry data

Vapor pressure (25oC) 8.2 x 10-5 mm Hg (torr) Product Chemistry data

Water Solubility (pH 7, 20oC) 0.3 mg/L Product Chemistry data

Henry’s law constant (KH) 1.2 x 10-4 atm M3

/mole Calculated from molecular 

weight and solubility
21

Log Octanol/Water Partition 

Coefficient (log Kow) (22oC)

5.11 MRID 41890101 

Log Octanol/Air Partition Coefficient 

(log Koa) 

7.39 Estimated with EPI SuiteTM

4.11a

Biomagnification Potential

Presumption*: If log KOA >5, log KOW >2 

and the rate of chemical transformation is 

low, the chemical may bio-magnify in 

terrestrial food chains►

For ethalfluralin, the log KOW=5.11 easily 

meeting the criterion, but the rate of 

transformation in tissues of biota is relatively 

fast. Therefore it cannot be confirmed that 

ethalfluralin has a potential to bio-magnify in 

terrestrial food chains. In fish, ethalfluralin 

did bioaccumulate (BCF range: 1040 –

1560X) but also rapidly depurated with a 

depuration half-life of 3 days, which suggests 

it may be metabolized in fish and excreted

(MRID 41994902). 

► Gobas et al. 2003 and 

Armitage & Gobas, 2007 5

support this presumption utilized 

here only as a broad reference to 

determine the potential for 

biomagnification in terrestrial 

food webs and is based on 

slowly-metabolized chemicals.

a http://www.epa.gov/tsca-screening-tools/download-epi-suitetm-estimation-program-interface-v411

Summary of Fate Properties of Ethalfluralin.

PROPERTY VALUE DATA SOURCE COMMENTS

Hydrolysis Stable at pH 3,6, and 

9

MRID # 000948-05

Henry’s Law Constant 1.2 x 10-4 atm M3

/mol One-Liner Calculated value

Aqueous Photolysis 

half-life (days)

0.263 MRID 41613916 t 1⁄2 = 6.3 hours

Soil Photolysis half-life 

(days)

14.2 MRID 41613917 There was increased volatilization 

of 14C residues in dark vs. 

irradiated soil, study is 

supplemental.

Aerobic Soil 

Metabolism

half-life (days), 25 oC

42.9

17.4

33.6

19.0

95% Upper C.I. mean 

= 48.5 days

MRID 41613918

MRID 48915601

Half-lives were normalized to 25 

oC (e.g., MRID 48915601 study 

conducted at 20 oC.)

Anaerobic Soil 

Metabolism

half-life (days)

13.8 MRID 41613919

Aerobic Aquatic 

Metabolism half-life 

(days)

No study submitted

Previously waived; but at this time 

it is believed a study could add 

value to the environmental fate 

knowledge base for ethalfluralin.

 5 Gobas, F.A.P.C., B.C. Kelly and J.A. Arnot. 2003. Quantitative structure activity relationships for predicting the 

bioaccumulation of POPs in terrestrial food webs. QSAR Comb. Sci. 22:329-336.
22

Anaerobic Aquatic 

Metabolism half-life 

(days) 1.58 MRID 42930102

Freundlich Adsorption 

Coefficient (Kf)

Nueces Sand, 0.5% 

O.M.: 11.9 (1/n = 

0.956) 

Fox Sandy Loam, 1.4% 

O.M.: 32.6

(1/n = 0.954) 

Crosby Loam, 1.8% 

O.M.: 53.0 (1/n = 

0.963)

Brookston Clay Loam, 

2.0% O.M.: 97.0

(1/n = 0.986)

MRID 42437202 Koc values not calculated in study.

Organic Matter 

Partitioning 

Coefficient (Koc)

3,957 ml/g

Range: 3957 to

8361 (Kfoc)

MRID 42437202 Additional data also available from 

European study for 4 soils6

Terrestrial Field 

Dissipation

half-life (days), field 

conditions

23 (silty clay loam, 

IL)

28 (sandy loam, GA)

51 (loam, CA)

MRID:

41978101

00094819

41441401

41613920

41978101

Fish Accumulation 

(BCF); concentration in 

tissue to exposure 

concentration in water: 

1330X for whole fish, 

1560X for muscle, and 

1040X for the remainder

(Wet weight). 

Depuration was rapid 

with a removal halflife of 3 days after 

exposure ceased,

MRID 41994902

. 

4.2 Exposure Pathways

Ethalfluralin parent compound is considered to be the primary stressors for aquatic and terrestrial 

organisms in this risk assessment. Ethalfluralin degrades in soils and aquatic systems into minor 

degradation products (<6% each) and exposure to these degradation products may be considered 

minimal. There is also evidence of significantly lower phytotoxicity of degradation products7. 

 6 Additional data from European Union dossier Koc range 3967-8083 mL/g. See: 

http://sitem.herts.ac.uk/aeru/footprint/en/Reports/271.htm . 7 James, E.H.,, M.S. Kemp and S.R. Moss2 1995. Phytotoxicity of trifluoromethyl- and methyl-substituted 

dinitroaniline herbicides on resistant and susceptible populations of black-grass (Alopecurus myosuroides). Pesticide 

Science 43:273–277.

Elizabeth H. James1, Malcolm S. Kemp1 and Stephen R. Moss2,*
23

The following description of exposure pathways therefore places emphasis on the environmental 

fate of and exposure to parent ethalfluralin.

In surface waters, ethalfluralin is likely to be quickly and predominantly partitioned to 

sediments, however, the available monitoring studies all focus on dissolved concentrations of 

ethalfluralin. 

Adsorption is the highest in soils that are very rich in organic matter or clay content and 

absorbed herbicide activity is very high. Therefore, higher application rates that are 

recommended on the product labels for these types of soils are consistent with the more rapid 

loss of available active ethalfluralin.

 

Aquatic Exposure

Although ethalfluralin is not particularly mobile, it has potential to be transported to water bodies 

and aquatic habitats in both a dissolved state in runoff or in a sorbed state to erodible soil 

particles as well as by drift from spray applications. Limnetic organisms (fish, aquatic 

invertebrates and plants) which occupy the water column may be exposed to ethalfluralin. 

Exposure is also expected to occur for benthic and sediment-dwelling organisms given that 

ethalfluralin readily partitions to sediment and organic matter given its measured Koc in the range 

between 3957 and 836l mL/g. 

The low to moderate persistence and strong sorption capacity of ethalfluralin in the environment 

lends itself to being available to runoff primarily via the process of erosion. This process is 

likely to be more significant if rain occurs shortly after application. Furthermore, off-site spray 

drift deposition of ethalfluralin to water bodies nearby applications may also result in exposure 

of aquatic organisms. 

Terrestrial Exposure

• Dietary Exposure: Direct dietary exposure to non-target terrestrial organisms (birds and 

mammals) is possible with the application of ethalfluralin. Ethalfluralin is applied prior to

and post emergence of crops; insectivores and granivores may ingest food items possessing 

the ethalfluralin residues. Dietary exposure is also possible given the moderate persistence

of ethalfluralin in the terrestrial environment.

Furthermore, indirect dietary exposure may result from aquatic exposure to fish (discussed 

above). Therefore, piscivorous birds and mammals feeding on contaminated fish may 

potentially be exposed. Bioaccumulation potential of ethalfluralin residues is possible in fish 

given ethalfluralin’s high Log Kow value of 5.11. There is uncertainty in this route of 

exposure since there is relatively rapid metabolism/depuration in fish. 

• Terrestrial plants: Exposure may occur via the runoff of residues off-site from treated 

fields to adjacent lands covered with non-targeted vegetation. Furthermore, off-site 

deposition of ethalfluralin due to spray drift may also occur.
24

• Terrestrial invertebrates: Dietary and contact exposure for terrestrial invertebrates are 

possible pathways with ethalfluralin applications. 

4.3 Aquatic Exposure Analysis

Aquatic Exposure Estimation Modeling

Estimated exposure concentrations for aquatic animals and plants in surface waters for labeled 

ethalfluralin applications are estimated using The Surface Water Concentration Calculator 

interface (SWCC; version 1.106; dated May 22, 2014). The SWCC is available on-line at: 

http://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/models-pesticide-riskassessment. Primarily to test the predicted impact of simulation of volatilization on the exposure 

estimate, limited additional model runs were made with a replacement version of this model that 

was not officially adopted by EFED at the time of this assessment (the Pesticide Water 

Calculator), this can reduce the calculated EECs by up to 5% for ethalfluralin.

In this assessment, exposure estimates for each of the current uses represent the highest and most 

vulnerable exposure for ethalfluralin use sites across the country. For all of the agricultural crop 

uses, broadcast surface spray applications to bare ground with very shallow incorporation is

evaluated since this is the conservative application scenario for runoff. For the FL cucumber 

scenario (which yielded the highest EECs of any modeled scenario) this assumption increases 

acute and chronic EEC estimates by 25 to 30% versus assuming a uniform incorporation to a 4 

cm depth (See Appendix C.) However, estimated environmental concentrations (EECs) in the 

water column for aquatic habitat are mostly dominated by spray drift deposition directly in the 

receiving water body. The fate parameters and use-specific input parameters for the SWCC 

surface water modeling are shown in Table 5 and Table 6, respectively. The EECs of 

ethalfluralin in surface water are summarized in Table 7. A more detailed EEC summary and 

selected SWCC input / output files are provided in Appendix C. Model inputs were selected 

following the input parameter guidance found here: https://www.epa.gov/pesticide-science-andassessing-pesticide-risks/guidance-selecting-input-parameters-modeling .

Table 5. Ethalfluralin physicochemical and fate property inputs for the SWCC model.

PROPERTY VALUE DATA SOURCE COMMENTS

Molecular Weight 333.27 Product Chemistry

Hydrolysis Stable MRID # 000948-05

Water Solubility (pH 7, 

20 oC)

0.3 mg/L Product Chemistry 

data

Water Solubility (pH 7, 20oC)

Vapor pressure (25 oC) 8.2 x 10-5 mm Hg Product Chemistry 

data Vapor pressure (25 C)
25

Aerobic Soil 

Metabolism

half-life (days), 25 oC

95% Upper C.I. mean 

= 48.5 days

MRID 41613918

MRID 48915601

Half-lives were normalized to 25 

oC (e.g., MRID 48915601 study 

conducted at 20 oC.) 95% C.I. due 

to uncertainty regarding 

identification of all residues.

Aerobic Aquatic 

Metabolism half-life 

(days)

97

2 X the aerobic soil metabolism 

half-life input (per guidance when 

direct data are not available.)

Anaerobic Aquatic 

Metabolism half-life 

(days) 1.58 MRID 42930102

Organic Matter 

Partitioning 

Coefficient (Kfoc)

3957 ml/g MRID 42437202 Koc value for sandy loam;

lowest value among 4 soils8

, used 

to provide a conservative estimate 

of runoff.

Table 6. SWCC crop scenario and application-related input parameter values for 

ethalfluralin aquatic exposure estimation.

Use Represented Scenario IDs

Application 

dates (for 

separate 

simulations

# of applications 

/ year

Application rate

(kg ai /ha)

Soybeans IL Corn STD

KS Corn Std

MS corn STD

MS soybean STD

NC corn STD

OH Corn STD

PA corn STD

June 10

June 25

October 10

October 25

1 1.47

Sunflower 

(conservative for 

other oilseed crops)

ND Canola Std

KS corn Std

15-May

10-Jun

10-Oct

25-Oct

1 1.91

Cucurbits FL Cucumber Std October 15

October 30 1 1.91

Peanuts NC Peanut std October 10 1 1.29

Dry Beans

(conservative for 

lentils) MI Dry beans Std October 25 1 1.89

Potatoes ID New Potato Std May 10 1 1.15

Alfalfa, Clover

(conservative for 

dill)

CA Alfalfa Std January 10 1 1.89

 8 European Union dossier Koc range 3967-8083 mL/g. See: 

http://sitem.herts.ac.uk/aeru/footprint/en/Reports/271.htm .
26

6

Spray drift fraction for aerial and ground applications from Table 2 of EPA, 2013, “Guidance on Modeling Offsite Deposition of Pesticides 

via Spray Drift”.

.

The maximum aquatic EECs (peak, 21-day and 60-day) by crop based on the SWCC farm pond 

scenario are summarized in Table 7 (representing multiple scenarios and application dates 

tested, full results are provided in Appendix C. Benthic sediment concentrations were also 

estimated with the peak and 21-day concentrations of 77.6 μg a.i. /L (parts per billion of dry 

sediment; ppb) and 52.8 ppb, respectively.

Table 7. SWCC estimated upper-bound peak, 21-day and 60-day concentrations in the surface water column 

and sediment for ethalfluralin at the highest application rate for proposed crop uses.

Crop Represented

(Scenario ID)

Concentration

μg/L

Applicat. 

Date Peak 21-day 60-day

Soybeans Oct. 10 6.51 2.6 --- (MS Corn)

Soybeans Oct. 25 --- --- 1.36

(MS Corn)

Sunflower+

Jun. 10 7.69 2.92 1.2

(KS Corn) 

Cucurbits

Oct. 30 12.5 3.55 1.36 (FL Cucumber)

Peanut

May 1 4.12 1.37 0.57

(NC Peanut)

Dry Beans May 15 5.9 1.69 0.71

(MI Beans)

Potatoes

May 10 5.9 1.69 0.71

(ID New Potato)

Alfalfa and Clover

Jan. 10 5.81 2.09 0.96

(CA Alfalfa OP)

Water Quality Monitoring Data

Due to its low overall usage profile and relatively low propensity to remain in the dissolved 

phase in surface waters, there are relatively few detections of ethalfluralin almost all at sub ppb 

levels for surface waters and sub ppt levels for groundwater. These data are provided for 

perspective, but the monitoring data are largely not associated with ethalfluralin usage profiles to 

facilitate an understanding of the loadings associated with the monitoring data. These data cannot 
27

be verified to provide an indication of the maximum aquatic exposure potential or the usage 

pattern associated with relatively high levels in water. In addition, monitoring for ethalfluralin 

does not provide a complete picture of ecological exposure potential because of the lack of 

monitoring associated with dissolved organic material or sediment. 

Combined Water Quality Portal Data

A search of the National Water Quality Monitoring Council’s Water Quality Portal (WQP9) was 

conducted on 1/21/2016. The WQP includes data collected by over 400 state, federal, tribal, and 

local agencies along with large previously separate databases associated with STORET, USGS 

National Water Quality Monitoring Program (NAWQA) and other important monitoring sources. 

Out of a total of 31,637 samples (both surface and groundwater) analyzed for ethalfluralin there 

were 185 detections of ethalfluralin at concentrations between 0.01 and 0.768 ppb; there 3 

detections above 0.1 ppb. Since none of these data verified a potential for ethalfluralin to occur 

in surface waters at concentrations greater than modeled, further detailed investigation of the 

nature of the available monitoring data was not conducted for this assessment. 

USDA Pesticide Data Program

Drinking water monitoring data collected by USDA's Pesticide Data Program (PDP) are available 

for ethalfluralin for the years 2003 to 2014. During this time period, a total of 1,253 water samples 

were collected none of which contained detectable residues of ethalfluralin. 

NAWQA Surface Water Monitoring

The USGS NAWQA10 data warehouse was searched on 12/23/2010 (the NAWQA data are now 

included in the WQP for which an updated search including NAWQA was conducted on 

1/21/2016.). Ethalfluralin was detected at concentrations between 0.005 and 0.768 ug/L (ppb) in 

190 of 22,876 surface water samples (0.83% detection frequency) collected across the United 

States11. The detection rate was higher in older samples - 1.49% out of 2,006 stream water 

samples collected from 1992 to 2001 with a minimum detection limit of 0.005 ppb or less for all 

samples analyzed; the higher rate could be because of higher use of ethalfluralin in the earlier 

time period and/or be due to differences in study area concentrations over the years.

The highest number of detections of ethalfluralin occurred in the following states (with 5 or more 

detections):

• 113 in California

• 39 in Washington

• 16 in Colorado

• 15 in Idaho

 9 WQP is a cooperative service cosponsored by the United States Geological Survey (USGS) and the Environmental 

Protection Agency (EPA),

10 http://infotrek.er.usgs.gov/nawqa_queries/swmaster/index.jsp (visited December 23, 2010) 11 The NAWQA long-term monitoring program has focus areas across the US that change over time. There were an 

additional 26 detections below 5 ppt, but levels below 5 ppt would be undetectable if present in most samples 

because the practical minimum detection limit was at or near 5 ppt in most cases. 
28

• 9 in North Dakota

There was a definite geographic concentration of the detections with the following watersheds 

/sites having the highest rate of detections:

(1.) 77 detections at ORESTIMBA CR AT RIVER RD NR CROWS LANDING CA 

(Stanislaus Co., CA)

(2.) 17 detections at SAN JOAQUIN R NR VERNALIS CA (San Joaquin Co., CA)

(3.) 12 detections at ROCK CREEK AB HWY 30/93 XING AT TWIN FALLS ID (Twin 

Falls Co., ID)

(4.) 11 detections at LONETREE CREEK NEAR GREELEY CO. (Weld Co., Colorado)

NAWQA Ground-Water Monitoring

The USGS NAWQA data warehouse was searched on 12/23/2010 (also updated in a WQP 

search on 1/21/2016). Ethalfluralin was detected at concentrations between 0.005 and 0.090 ppb

in 3 of 8,528 ground-water samples (0.035% detection frequency) collected across the United 

States. The sample which contained 0.090 ppb ethalfluralin (from Franklin County, Washington) 

was the only sample with greater than 0.006 ppb ethalfluralin.

4.4 Clean Water Act

Ethalfluralin is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act, based on information provided 

at http://iaspub.epa.gov/waters10/ez_where.retrieval_list .

In addition, no Total Maximum Daily Load (TMDL) has been developed for ethalfluralin, based 

on information provided 

at http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_i

d=885&p_pollutant_group_name=PESTICIDES. More information on impaired water bodies 

and TMDLs can be found at http://www.epa.gov/owow/tmdl/. 

4.5 Terrestrial Exposure Analysis

In order to estimate risks of ethalfluralin exposures in terrestrial environments, all exposure 

modeling and resulting risk conclusions will be based on maximum application rates for a given 

use. Measures of exposure are based on terrestrial models that predict EECs of ethalfluralin. 

. 

4.5.1 Terrestrial Animal (Birds (surrogates for reptiles and terrestrial-phase 

amphibians) and Mammals) Dietary Exposure Estimation

Ethalfluralin may be applied as either a ground application using an emulsified concentrate or in 

granular form which will reduce exposure relative to foliar application. For ground applications 

of emulsifiable concentrate, birds and mammals may be exposed to pesticide residues after 
29

application through oral or dietary exposure to seeds or insects when foraging in the treated 

fields for nesting material or food. Therefore estimation of pesticide concentrations in wildlife 

food items focuses on quantifying possible dietary ingestion of residues on vegetative matter and 

insects. The EFED terrestrial exposure model T-REX (T-REX, Version 1.5, released 03/2012) is 

used to estimate exposures and risks to avian and mammalian species. Input values for avian and 

mammalian toxicity as well as chemical application rates and foliar dissipation half-life data are 

required to run the model. The model provides estimates of exposure concentrations and risk 

quotients (RQs). Specifically, the model provides estimates of concentrations (upper-bound and 

mean) of chemical residues on the surface of different types of foliage and insects that may be 

dietary sources of exposure to avian, mammalian, reptilian, or terrestrial-phase amphibian 

receptors. The surface residue concentration (in mg ai/kg; parts per million; ppm) is estimated 

by multiplying the application rate (pounds active ingredient per acre) by a value specific to each 

food item. These values (termed the Hoerger-Kenaga estimates) along with a more detailed 

discussion of the methodology implemented by T-REX, are presented in Appendix E (T-REX 

Model). By comparing EECs to acute and chronic toxicity reference values, RQs are calculated. 

The EECs on food items may be compared directly with dietary toxicity data or converted to an 

oral dose. The residue concentration is converted to daily oral dose based on the fraction of body 

weight consumed daily as estimated through allometric relationships. The screening-level risk 

assessment for ethalfluralin uses upper-bound predicted residues as the measure of exposure. 

Consideration is given to different types of feeding strategies, including herbivores, insectivores 

and granivores. Dose-based exposures are estimated for three weight classes of birds (20 g, 100 

g, and 1000 g) and three weight classes of mammals (15 g, 35 g, and 1000 g). Summaries of the 

predicted upper-bound residues of ethalfluralin that may be expected to occur on selected avian 

or mammalian food items immediately following application for the maximum use scenario are 

presented in Tables 11, 12, and 13.

4.5.2 Spray Applications

Input values for the endpoints used for estimating avian and mammalian exposure risks to 

ethalfluralin are summarized in Table 8. For spray applications the default value for foliar halflife of 35 days was used for ethalfluralin residues on plants. The application rates and 

application methods are summarized above in Table 10 of the uses and consist of both spray 

applications and granular applications. 

Table 8. Input parameters for endpoints used in T-REX v 1.2.5 to determine terrestrial 

RQs.

Input Parameters Value Source

Avian Oral LD50 >2000 mg/kg-bw (zebra finch) MRID 48915502

Avian Dietary 5000 ppm (bobwhite quail) Acc. No. 070677
30

Avian Reproduction NOEAC 1000 ppm (mallard duck) Acc. No 00094763

Mammal LD50 5000 mg/kg-bw (rat) Acc. No 00135189

Mammal NOAEC 61 mg/kg-bw (rat) Acc. No 0094784 and 

MRID 42300301

For the maximum ethalfluralin application scenario of 1.69 lbs ai/A, concentrations for different 

avian forage types ranged from 1 to 462 ppm for dose-based upper-bound residues (Table 9) and 

7 to 164 ppm for mean residues from emulsified concentrate applications. Mammalian dose-based 

residues ranged from 1 to 387 ppm (Table 10). Dietary residue concentrations ranged from and 

15 to 406 ppm (Table 11). EECs that resulted from granular applications ranged from 1.2 to 2.11 

mg ai ft-2 (Table 12). 

Table 9. Avian TREX upper-bound dose-based EECs (mg/kg)

. 20 g "Small" Bird 100 gram "Medium" Bird 1000 gram "Large" Bird

Use (application

rate lbs a.i./A)

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Alfalfa with low 

broadcast spray 

(1.698)

462 212 260 29 181 6.4 263 121 148 16 103 3.7 118 54.1 66 7.4 46 1.6

Potatoes 

chemigation (1.028) 281 129 158 18 110 3.9 160 73 90.1 10 63 2.2 72 32.9 40 4.5 28 1

Sunflower (1.3) 

granular, 

incorporated, 

chemigation

355 163 200 22 139 4.9 203 93 114 13 79 2.8 91 41.6 51 5.7 36 1.3
31

Table 10. Mammalian TREX dose-based EECs (mg/kg).

15 gram "Small" Mammal 35 gram "Medium" Mammal 1000 gram "Large" Mammal

Use (application 

rate lbs a.i./A)

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Alfalfa with low 

broadcast spray 

(1.698)

387 177 218 24 151 5 267 122 150 17 105 4 62 28 35 4 24 1

Potatoes 

chemigation 

(1.028)

235 108 132 15 92 3 163 75 91 10 64 2 38 17 21 2 15 1

Sunflower (1.3) 

granular, 

incorporated, 

chemigation

297 136 167 19 117 4 206 94 116 13 81 3 48 22 27 3 19 1

Table 11. T-REX dietary based EECs.

Use (application rate 

lbs a.i./A)

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Alfalfa with low 

broadcast spray 

(1.698)

406 186 228 25 159

Potatoes chemigation 

(1.028) 247 113 139 15 97

Sunflower (1.3) 

granular, 

incorporated, 

chemigation

312 143 176 20 122
32

4.5.3 Granular applications

For granular applications of ethalfluralin T-REX (v. 1.5.2; 03/22/2012) is able to calculate the 

LD50 ft-2 risk index values for the labeled uses. The assumed incorporation of these methods of 

application is 85%. Thus 15% of the chemical is assumed to be available for consumption by 

both avian and mammalian taxa. The LD50 ft-2 value is calculated using a toxicity value (adjusted 

LD50) and the EEC (mg a.i. ft-2) and is directly compared with the Agency’s levels-of-concern 

(LOCs). As with EC formulations, consideration is given to different types of feeding strategies 

including herbivores, insectivores and granivores. Dose-based exposures are estimated for three 

weight classes of birds (20 g, 100 g, and 1000 g) and three weight classes of mammals (15 g, 35 

g, and 1000 g). The EECs that result from granular formulations is presented in Table 14.

Table 12. Estimated LD50/ft2 (in mg active ingredient (a.i.) per square foot) from granular 

applications of ethalfluralin across uses.

Use (application rate lbs a.i./A) mg a.i/ft2

Clover 3" incorporated (1.35) 2.11

Lentils, mustard granular formulation 

incorporated (0.95) 1.48

Peanuts granular formulation (1.15) 1.8

Peas granular formulation (0.76) 1.2

Safflower granular 1.15) 1.8

Safflower incorporated (1.142) 1.78

Soybeans granular (1.33) 2

Sunflower (1.3) granular, incorporated, 

chemigation 2

4.5.4 Terrestrial Plant Exposure Estimation

The routes of exposure to terrestrial plants for ethalfluralin include off-site transport via spray 

drift and runoff. The TerrPlant model (v. 1.2.2; December 26, 2006) evaluates terrestrial plant 

exposure contributions from runoff and spray drift. It is used to derive EECs relevant to 

terrestrial and wetland plants. The model employs the assumption that default fractions of the 

intended application are transported to an adjacent field through runoff and spray drift. There is 

not any drift assumed for granular applications and more accurate measures of off-site drift is 

modeled using the AgDrift model. Measures of exposure to terrestrial plants are expressed as a 
33

fraction of the mass of the ethalfluralin applied to the treated field. TerrPlant EECs are shown in 

Table 13 below.

Table 13. TerrPlant EECs (lbs. a.i. /A) for ethalfluralin exposure to terrestrial and wetland 

plants resulting from runoff and spray drift.

Use (application rate - lbs a.i./A) Description of Area

EEC

(lbs a.i/A)

Alfalfa, Beans, Cucurbits with low broadcast spray 

EC1 (1.698)

Runoff to dry areas 0.017

Runoff to semi-aquatic areas 0.17

Spray drift 0.017

Total for dry areas 0.034

Total for semi-aquatic areas 0.187

Alfalfa, Beans with chemigation EC3 (1.698)

Runoff to dry areas 0.017

Runoff to semi-aquatic areas 0.17

Spray drift 0.085

Total for dry areas 0.102

Total for semi-aquatic areas 0.255

Beans granular (1.69)

Runoff to dry areas 0.017

Runoff to semi-aquatic areas 0.17

Spray drift 0

Total for dry areas 0.017

Total for semi-aquatic areas 0.17

Clover 3" incorporated (1.5)

Runoff to dry areas 0.005

Runoff to semi-aquatic areas 0.05

Spray drift 0.015

Total for dry areas 0.02

Total for semi-aquatic areas 0.065

Dill ground spray (1.13)

Runoff to dry areas 0.015

Runoff to semi-aquatic areas 0.15

Spray drift 0.015

Total for dry areas 0.03

Total for semi-aquatic areas 0.165

Lentils, Mustard granular formulation 2" 

incorporation (0.95)

Runoff to dry areas 0.00475

Runoff to semi-aquatic areas 0.0475

Spray drift 0

Total for dry areas 0.00475

Total for semi-aquatic areas 0.0475

Runoff to dry areas 0.0085
34

Use (application rate - lbs a.i./A) Description of Area

EEC

(lbs a.i/A)

Oilseed-Sunflower, Jojoba, etc (1.7) Granular 2 inch 

incorporation

Runoff to semi-aquatic areas 0.085

Spray drift 0

Total for dry areas 0.0085

Total for semi-aquatic areas 0.085

Oilseed-Sunflower, Jojoba, etc (1.7) Granular F 3 

inch incorporation

Runoff to dry areas 0.005667

Runoff to semi-aquatic areas 0.056667

Spray drift 0

Total for dry areas 0.005667

Total for semi-aquatic areas 0.056667

Oilseed-Sunflower, Jojoba, etc (1.7) EC3 

chemigation

Runoff to dry areas 0.017

Runoff to semi-aquatic areas 0.17

Spray drift 0.085

Total for dry areas 0.102

Total for semi-aquatic areas 0.255

Oilseed – Crambe, Rapeseed (canola), etc. group 

(0.95) EC2 spray with 2 inch incorporation

Runoff to dry areas 0.00475

Runoff to semi-aquatic areas 0.0475

Spray drift 0.0095

Total for dry areas 0.01425

Total for semi-aquatic areas 0.057

Oilseed – Crambe, Rapeseed (canola), etc. group 

(0.95) Granular with 2 inch incorporation

Runoff to dry areas 0.00475

Runoff to semi-aquatic areas 0.0475

Spray drift 0

Total for dry areas 0.00475

Total for semi-aquatic areas 0.0475

Oilseed-Safflower (1.15) granular with 2 inch 

incorporation

Runoff to dry areas 0.00575

Runoff to semi-aquatic areas 0.0575

Spray drift 0

Total for dry areas 0.00575

Total for semi-aquatic areas 0.0575

Peanuts granular formulation (1.15) with 2 inch 

incorporation

Runoff to dry areas 0.00575

Runoff to semi-aquatic areas 0.0575

Spray drift 0

Total for dry areas 0.00575

Total for semi-aquatic areas 0.0575

Peanuts EC with 2 inch incorporated (1.15)

Runoff to dry areas 0.00575

Runoff to semi-aquatic areas 0.0575

Spray drift 0.0115
35

Use (application rate - lbs a.i./A) Description of Area

EEC

(lbs a.i/A)

Total for dry areas 0.01725

Total for semi-aquatic areas 0.069

Peas EC (0.75) 2 inch incorporation

Runoff to dry areas 0.00375

Runoff to semi-aquatic areas 0.0375

Spray drift 0.0075

Total for dry areas 0.01125

Total for semi-aquatic areas 0.045

Peas granular formulation (0.75) 2 inch 

incorporation

Runoff to dry areas 0.00375

Runoff to semi-aquatic areas 0.0375

Spray drift 0

Total for dry areas 0.00375

Total for semi-aquatic areas 0.0375

Potatoes chemigation (1.028)

Runoff to dry areas 0.00514

Runoff to semi-aquatic areas 0.0514

Spray drift 0.0514

Total for dry areas 0.05654

Total for semi-aquatic areas 0.1028

Potatoes ground (1.028)

Runoff to dry areas 0.00514

Runoff to semi-aquatic areas 0.0514

Spray drift 0.01028

Total for dry areas 0.01542

Total for semi-aquatic areas 0.06168

Soybeans Granular (1.3) 2 inch incorporation

Runoff to dry areas 0.0065

Runoff to semi-aquatic areas 0.065

Spray drift 0

Total for dry areas 0.0065

Total for semi-aquatic areas 0.065

4.5.5 Terrestrial Invertebrate Exposure Estimation

Drift from the boom sprayers or residues may come into contact with pollinators either through 

direct contact or ingestion of residues in pollen/nectar. Possible exposures from either acute 

contact or oral exposure to the proposed applications rates were calculated using Bee-Rex model

(version 1.0). To calculate contact exposure, the application rate was multiplied by 2.7 μg a.i. 

/bee. Oral exposure was calculated by multiplying the application rate by ((110 μg a.i. /g) *

0.292g/day)). For details see the Guidance for Assessing Pesticide Risks to Bees (USEPA, 
36

2014). Estimated dose exposure concentrations for honeybee (Apis mellifera) contact and oral 

exposure are presented in Table 14 resulting from each representative ethalfluralin uses. 

Table 14. Ethalfluralin contact and oral estimated exposure dose 

concentrations to honeybees.

Use (Application Rate -

lbs a.i./A)

Contact Exposure 

(mg/kg)

Oral Exposure 

(mg/kg)

Alfalfa with low broadcast spray 

(1.698) 4.5 54.5

Potatoes chemigation (1.028) 2.8 33

Sunflower (1.3) granular, incorporated, 

chemigation 3.5 41.8

4.5.6 Picivorous Avian and Mammal exposure to fish containing ethalfluralin residues

The KABAM model (Kow (based) Aquatic BioAccumulation Model; version 1.0) was used to 

evaluate the potential exposure and risk of direct effects to birds and mammals via 

bioaccumulation and biomagnification in aquatic food webs. KABAM is used to estimate 

potential bioaccumulation of hydrophobic organic pesticides in freshwater aquatic ecosystems 

and risks to mammals and birds consuming aquatic organisms which have bioaccumulated these 

pesticides. The bioaccumulation portion of KABAM is based upon work by Arnot and Gobas 

(2004) who parameterized a bioaccumulation model based on polychlorinated biphenyls (PCBs)

and some pesticides (e.g., lindane, DDT) in freshwater aquatic ecosystems (Arnot and Gobas, 

2004). KABAM relies on a chemical's Kow to estimate uptake and elimination constants through 

respiration and diet of organisms in different trophic levels. Pesticide tissue residues are 

calculated for different levels of an aquatic food web. The model then uses pesticide tissue 

concentrations in aquatic animals to estimate dose- and dietary-based exposures and associated 

risks to mammals and birds (surrogate for amphibians and reptiles) consuming aquatic 

organisms. Seven different trophic levels including phytoplankton, zooplankton, benthic 

invertebrates, filter feeders, small-sized (juvenile) forage fish, medium-sized forage fish, and 

larger piscivorous fish, are used to represent an aquatic food web. Importantly, chemical 

metabolism by biota is assumed to be zero in KABAM so modeling will indicate worse case 

scenarios of exposure. Input scenarios and parameters were chosen to represent the range of 

exposures from high to low and are presented in Table 15. Example output from the 

bioaccumulation model is provided in Appendix F. 

Table 15. Input parameters for KABAM model.

Parameter Input Value Source

Pesticide Name Ethalfluralin

Log KOW 5.11 MRID 41890101

KOC 3957-8391L/kg O.C. MRID 42437202
37

Parameter Input Value Source

Use patterns Acute Concentration in water 

column(ppb)

Acute Concentration in pore water 

(ppb)

Cucurbits (1.7 lb 

a.i./A) 12.5 0.49

Soybean (1.3 lb a.i./A) 6 0.19

Based on KABAM results and no depuration, estimated concentrations of ethalfluralin residues 

in the tissue of organisms in the different trophic levels following application on cucurbits range 

from 72,690 μg/kg to 174,190 μg/kg (Table 16). The measured bioconcentration factors 

(BCF’s) in the laboratory were 1330 L/Kg in the whole fish (MRID 41994902) while the 

KABAM model estimated a BCF for large fish of 6191. This suggests that KABAM may 

overestimate the bioaccumulation of ethalfluralin and therefore overestimate the risk from 

consumption of fish from contaminated water bodies. One reason for this discrepancy between 

measured and predicted values may be that ethalfluralin is able to rapidly depurate in fish tissues 

(3 days) and the KABAM models assumes no depuration. So while the Kow indicates that 

ethalfluralin has a strong tendency to bioaccumulate and this is a possible route of exposure, it is 

likely that the exposure modeled by KABAM represents a worst case scenario.

Table 16. Estimated concentrations of ethalfluralin in ecosystem components.

Ecosystem 

Component

Total 

concentration 

(μg/kg-ww)

Lipid 

normalized 

concentration 

(μg/kg-lipid)

Contribution 

due to diet 

(μg/kg-ww)

Contribution 

due to 

respiration 

(μg/kg-ww)

Phytoplankton 72,690 3634482 N/A 72,689.64

Zooplankton 56,920 1897330 2,222.15 54,697.75

Benthic 

Invertebrates 61,641 2054701 5,607.68 56,033.37

Filter Feeders 40,471 2023530 3,612.90 36,857.70

Small Fish 94,288 2357210 24,355.55 69,932.85

Medium Fish 115,675 2891869 48,653.60 67,021.15

Large Fish 174,190 4354746 107,805.01 66,384.81

5 Ecological Effects Characterization

This section contains the ecological effects characterization for ethalfluralin based upon registrantsubmitted toxicity data for the technical grade active ingredient (TGAI; parent ethalfluralin) and 

for specified formulations. Ethalfluralin is characterized as being very highly toxic to freshwater 

and estuarine/marine fish, aquatic-phase amphibians (for which freshwater fish serve as 

surrogates), and to freshwater invertebrates on an acute exposure basis. The compound is highly 

toxic to estuarine/marine invertebrates on an acute exposure basis. Chronic exposure resulted in 
38

reductions in growth in fish and freshwater invertebrates and reduced reproduction in 

estuarine/marine invertebrates. 

5.5 Aquatic Effects Summary

The effects of exposure to ethalfluralin on aquatic organisms were determined by assessing 

freshwater and estuarine/marine taxa. The most sensitive species that are used to assess risk in 

this assessment are listed in Table 18. Additionally, five chronic animal toxicity studies and one 

aquatic vascular plant toxicity study were submitted since the last assessment:

1) a chronic toxicity test with the sheepshead minnow (Cyprinodon variegatus; MRID 

48689101);

2) a chronic toxicity test with the freshwater daphnid (Daphnia magna; MRID 49086902);

3) a chronic toxicity test with the estuarine mysid shrimp (Americamysis bahia; MRID 

49037801);

4) a 10-day toxicity tests with the freshwater benthic invertebrate midge Chironomus dilutus 

(MRID 48975701);

5) a 10-day toxicity tests with the freshwater benthic invertebrate amphipod (Hyalella 

azteca; MRID 48975702); and,

6) a toxicity test with the vascular aquatic plant duckweed (Lemna gibba; MIRD 49086901).

These studies are marked in bold in Table 17 of the aquatic taxa endpoints. Only descriptions of 

these studies are provided below. Refer to previous assessments, (DP# D205884, D296985, and 

D296987) for more comprehensive descriptions of the studies that are not included here. 

Chronic Toxicity to Sheepshead minnow (Cyprinodon variegatus) (MRID 48689101)

The 33-day chronic toxicity of ethalfluralin to the early life-stage (ELS) of estuarine/marine 

sheepshead minnow was studied under flow-through conditions (MRID 48689101). The overall 

NOAEC and LOAEC was 1.2 and 2.7 μg ai/L respectively, based upon the 4% reduction in total 

length at the 2.7 μg ai/L levels. This study is classified as scientifically sound and satisfies the 

guideline requirements for an early life stage toxicity study with fish. 

Chronic Toxicity to the Freshwater Invertebrate (Daphnia magna) (MRID 49086902)

The 21-day-chronic toxicity of ethalfluralin to Daphnia was studied under flow-through 

conditions (MRID 49086902). The NOAEC and LOAEC were 71 and 150 μg ai/L, respectively, 

based upon a treatment-related reduction in both total body length (2% decrease) and dry weight

(13% decrease) at the 150 μg ai/L level. 

Chronic Toxicity to the Saltwater Mysid (Americamysis bahia) (MRID 48936801)

A 28-day life cycle toxicity test of ethalfluralin to mysids was studied under flow-through 

conditions (MRID 48936801). The NOAEC and LOAEC were 29.1 and 57.8 μg a.i. /L 
39

respectively based on a 32.4% reduction in young produced per female. This study is classified 

as acceptable.

Chronic Toxicity to the Midge (Chironomus dilutus) (MRID 48915701) 

A 10-day chronic toxicity test of ethalfluralin (MRID 48915701) was performed with the 

freshwater benthic invertebrate midge using spiked sediment. No treatment-related effects were 

observed on survival or growth following 10 days of exposure. The NOAEC and LOAEC for 

the endpoints normalized to organic carbon were 4800 and >4800 mg ai/kg total organic carbon

(TOC) or 270 μg a.i. /L and >270 μg a.i. /L for pore water. This study was classified as 

acceptable.

Chronic Toxicity to the Freshwater Amphipod (Hyalella azteca) (MRID 48915702) 

A 10-day chronic toxicity test of ethalfluralin (MRID 48915702) was performed with the 

freshwater benthic invertebrate amphipod using spiked sediment. Using mean-measured 

concentrations, the NOAEC and LOAEC for growth were 10 and 19 mg ai/kg (92 and 140 μg a.i. 

/L pore water), respectively, based on a 20% reduction in dry weight. The OC-normalized mean 

measured sediment concentration NOAEC and LOAEC endpoints are 480 and 900 mg ai/kg 

TOC respectively. 

Acute Toxicity of Ethalfluralin to Aquatic Vascular Plants (Lemna gibba) (MRID 

49086901)

In a 7- day acute toxicity study, the freshwater duckweed was exposed to ethalfluralin under 

static renewal conditions (MRID 49086901). The initial mean measured concentrations were 0 

(negative and solvent controls), 0.36, 1.7, 5.2, 18, 70, and 220 μg ai/L. The NOAEC value based 

on reductions in frond number yield and frond number growth rate was 1.7 μg ai/L and based on 

final biomass and biomass growth rate was 5.2 μg ai/L. The EC50/IC50 values based on frond 

number yield, frond number growth rate, final biomass, and biomass growth rate were 7.322, 

29.1, 36.77, and >220 μg ai/L, respectively, in terms of initial measured concentrations. 

Table 17. Summary of Acute and Chronic Toxicity Data for Aquatic Taxa Exposed to 

Ethalfluralin.

Exposure 

Scenario Species Scientific Name

Exposure 

Duration

Toxicity 

Reference 

Value 

(μg a.i./L)

Endpoints 

Affected

Reference

(Classification)

Freshwater Fish

Acute Bluegill 

Sunfish

Lepomis 

macrochirus 96 hours LC50 = 32 Mortality

Acc. 

No.00135183

Very Highly 

Toxic

(Acceptable)

Acute Rainbow 

Trout

Oncorhynch

us mykiss 96 hours LC50 = 37 Mortality

Acc. No. 

00135183

Very Highly 

Toxic

(Acceptable)
40

Chronic Rainbow 

Trout

Oncorhynch

us mykiss 60 day

NOAEC/ 

LOAEC = 

0.4/1.4 

Larval 

survival, 

length, 

weight

MRID 

41994901

(Acceptable)

Freshwater Invertebrate

Acute Waterflea Daphnia 

magna

96 hours LC50 =60 Mortality

Acc. No.

070677 Very 

highly toxic 

(Acceptable)

Chronic* Waterflea Daphnia 

magna 21 days

NOAEC/ 

LOAEC =24/ 

37 

Growth

MRID 

42930101 

(Acceptable)

Chronic Waterflea Daphnia 

magna 21 days

NOAEC/ 

LOAEC =71/ 

150 

Growth

MRID 

49086902 

(Acceptable)

Estuarine Fish

Acute Sheepshead 

Minnow

Cyprinodon 

variegatus 96 hours LC50=240 Mortality

MRID 

41613904, 

Highly Toxic 

(Acceptable)

Chronic Sheepshead 

Minnow

Cyprinodon 

variegatus

33 days 

(ELS)

NOAEC/ 

LOAEC = 1.2 

/ 2.7 

Length

MRID 

48689101

(Acceptable)

Estuarine Invertebrates

Acute Mysid 

Shrimp

Mysidopsis 

bahia 96 hours LC50=230 Mortality

MRID 

41613906

Highly Toxic

(Acceptable)

Acute Eastern 

Oyster

Crassotrea 

virginica 96 hours LC50=170 Mortality

MRID 

42889801

Highly Toxic

(Acceptable)

Chronic Mysid 

Shrimp

Mysidopsis 

bahia 28 days

NOAEC/ 

LOAEC = 

29.1/57.8

Offspring 

produced 

per female

MRID 

49037801

(Acceptable)

Aquatic Plants

NonVascularGreen 

Algae

Pseudokirchne

riella 

swubcapitata 

formerly 

Selenastrum 

capricornutum

120 hours

IC50 = 25 

Cell 

Density

MRID 

41613912

NOAEC=10.9 (Acceptable)

Vascular Duckweed Lemna 

gibba 14 days IC50 = 7.3 MRID 49086901
41

NOAEC=1.7 

Frond 

number 

yield

(Acceptable)

Sediment Invertebrates

Chronic Midge Chironomus

dilutus 10 day

NOAEC/ 

LOAEC =270, 

>270

NA

MRID 

48975701 

Acceptable

Chronic Amphipods Hyalella 

azteca 10 day

NOAEC/ 

LOAEC 

=92/140

Dry weight

MRID 

48975702 

Acceptable

*When two studies are presented, the most sensitive endpoint will be used for risk assessment purposes.

5.6 Terrestrial Effects Summary

Ethalfluralin is practically non-toxic to both mammals and birds, reptiles and terrestrial-phase 

amphibians (for which birds serve as surrogates) on an acute oral exposure basis; the compound 

is also practically non-toxic to birds on a subacute dietary exposure basis. Ethalfluralin is also 

practically non-toxic to young adult honey bees (Apis mellifera) on an acute contact exposure 

basis. Chronic exposure in both birds and mammals resulted in effects on reproduction.

The effects of ethalfluralin on terrestrial organisms that are used to assess risk in this assessment 

are listed in Table 18. Additionally, four new studies were submitted since the last assessment

that include:

1) an acute toxicity study with Japanese quail (Coturnix japonica; MRID 48915501);

2) an acute toxicity study with Zebra finch (Taeniopygia guttata; MRID 49385904); 

3) a vegetative vigor study with the formulated product Sonalan® HP (GF-1740) – 35.1% 

Ethalfluralin (MRID 48915901); and,

4) a seedling emergence study with the formulated product Sonalan® HP (GF-1740) - 35.1% 

Ethalfluralin (MRID 49385904). 

These studies are presented are marked in bold in Table 19 of the terrestrial taxa endpoints. 

Only descriptions of these studies are provided below. Refer to previous assessments for more 

comprehensive descriptions of the studies that are not included here. 

Acute Toxicity to Japanese Quail (Coturnix japonica) (MRID 48915501)

The acute oral toxicity of ethalfluralin to Japanese quail was assessed over 14 days in a limitdose study (MRID 48915501). No mortality, clinical signs of toxicity, or effects on body weight 

were observed at the limit dose of 2000 mg/kg bw. The acute oral LD50 was >2000 mg/kg bw. 

Ethalfluralin GF-705 is classified as practically non-toxic to the Japanese quail on an acute oral 

exposure basis. This toxicity study is classified as scientifically sound and satisfies the guideline 

requirement for an acute oral toxicity study. 
42

Acute Toxicity to the Zebra Finch (Taeniopygia guttata) (MRID 48915502)

The acute oral toxicity of ethalfluralin to passerine birds (i.e., Zebra finches) was assessed over 

14 days in a limit-dose study (MRID 48915502). No mortality, clinical signs of toxicity, or 

effects on body weight or food consumption were observed in the 2000 mg ai/kg bw group. The 

acute oral LD50 was >2000 mg ai/kg bw. Therefore ethalfluralin is classified as practically nontoxic to zebra finches on an acute oral basis. This toxicity study is classified as scientifically 

sound and satisfies the guideline requirement for an acute oral toxicity study with a passerine 

species. 

Toxicity of Ethalfluralin (Sonalan® HFP GF-1742) to Terrestrial Vascular Plants 

Vegetative Vigor (MRID 48915901)

The effect of formulated ethalfluralin (Sonalan® GF-1742; 35.1 % ethalfluralin) on the 

vegetative vigor of monocotyledonous (monocots: grain sorghum, sorghum bicolor; onion, 

Allium cepa; ryegrass, Lolium perenne; and oat, Avena sativa) and dicotyledonous (dicots: 

oilseed rape, Brassica napus; carrot, Daucus carola; soybean, Glycine max; cucumber, Cucumis 

sativus; sugar beet, Beta vulgaris, and tomato, Lycopersicon esculentum) crops was studied at a 

nominal treatment rates ranging from 0.007 to 1.68 lbs a.i./A (MRID 48915901). The most 

sensitive monocot was ryegrass, based on decreased fresh weight with NOAEC and IC25 values

of 0.053 and 0.212 lb ai/A, respectively. The most sensitive dicot species, could not be 

determined due to a lack of toxicity; NOAEC and EC/IC25 values were 1.68 and >1.68 lb ai/A, 

respectively.

Toxicity of Ethalfluralin (Sonalan® HFP GF-1742) to Terrestrial Vascular Plants Seedling 

Emergence (MRID 49385904)

The effect of formulated ethalfluralin (Sonalan® GF-1742; 35.1 % ethalfluralin) on the seedling 

emergence of monocots (corn, Zea mays; oat; onion; and ryegrass) and dicot crops (carrot; 

cucumber; oilseed rape; soybean; sugar beet, Beta vulgaris; and tomato) was studied at rates 

ranging from 0.00328 to 1.68 lb ai/A (MRID 49385904). The most sensitive monocot was 

ryegrass based on reduced fresh weight, with IC05 and EC25 values of 0.00195 and 0.0183 lb 

ai/A, respectively.

The most sensitive dicot species was tomato based on reduced fresh weight, with NOEC and 

EC25 values of 0.105 and 0.139 lb ai/A, respectively. Phytotoxic effects reported included

epinasty (bending outward), leaf cupping, lodging, stunting, chlorosis, necrosis, mosaic, leaf 

wrinkle, and complete mortality. 

Table 18. Summary of Toxicity for Terrestrial Taxa Exposed to Ethalfluralin.

Exposure 

Scenario Species Scientific Name

Exposure 

Duration

Toxicity 

Reference 

Value

Effects

Reference

(Classification)

Mammals
43

Exposure 

Scenario Species Scientific Name

Exposure 

Duration

Toxicity 

Reference 

Value

Effects

Reference

(Classification)

Acute Laboratory 

Rat

Rattus 

norvegicus Acute Oral

LD50 = 

5000

mg/kg bw

Mortality

Acc. No.

00135189 

(Acceptable)

Practically nontoxic

Chronic Laboratory 

Rat

Rattus 

norvegicus Chronic

NOAEL = 

61 mg/kgbw; 

LOAEL >

61 mg/kg 

bw

Reproduction

MRID 

43868313, 

44073701 

(Acceptable)

Invertebrates

Acute 

Contact Honey bee Apis mellifera 48 hours LD50>51 μg a.i./bee Mortality

MRID

41613914

(Acceptable) 

Practically nontoxic

Birds

Acute 

(Dosebased)

Bobwhite 

Quail

Colinus 

virginianus 14days

LD50 > 

2000 mg 

a.i./kg

Mortality

Acc. No.

00094760

(Acceptable) 

Practically nontoxic

Acute 

(Dosebased)

Japanese 

Quail

Coturnix 

coturnix 

japonica

14days

LD50

>2000 mg 

a.i./kg bw

Mortality

MRID 

48915501

(Acceptable) 

Practically 

non- toxic

Acute 

(Dosebased)

Mallard 

Duck

Anas 

platyrhynchos 14 days

LC50 = 

>5000 

mg/kg bw

Mortality

Acc. No.

00094762

(Acceptable) 

Practically nontoxic

Acute 

(Dosebased)

Zebra 

finch

Taeniopygia 

guttata 14 days

LD50

>2000 

mg a.i./kg

Mortality

MRID 

48915502

(Acceptable) 

Practically 

non- toxic

Acute 

(Dietarybased)

Bobwhite 

Quail

Colinus 

virginianus 8 days

LC50 

>5000 

mg/kg diet

N/A

Acc. No.

070677

(Acceptable)

Acute 

(Dietarybased)

Mallard 

Duck

Anas 

platyrhynchos 8 days

LC50 

>5000 

mg/kg diet

N/A

Acc. No.

070677 

(Acceptable)
44

Exposure 

Scenario Species Scientific Name

Exposure 

Duration

Toxicity 

Reference 

Value

Effects

Reference

(Classification)

Chronic Mallard 

Duck

Anas 

platyrhynchos

21 weeks

NOAEL = 

1000 

mg/kg diet

NOAEL 

>1000

mg/kg diet

N/A

Acc. No.

00094763 

(Acceptable)

Reproduction

Plants

Seedling 

Emergence

With TGAI

ND

Sorghum 

vulgare 21 days

EC25 = 

0.09 lb 

a.i./A

Plant weight

Acc. No.

47874101

(Monocot)

NOAEC = 

0.06lb 

a.i./A

Acceptable

Sugar beet

Beta vulgaris 21 days

EC25 = 

0.11 lbs 

a.i./A

Fresh Weight

MRID 

47874101

(Dicot)

NOAEL 

=0.1048 

lbs a.i./A

(Supplemental)

Seedling 

Emergence

ND

Lolium 

perenne 21 days

EC25 = 

0.0183 lb 

a.i./A

EC05 was 

used in lieu 

of NOAEC 

since IC25 

lower than 

NOEAEC

MRID 

49385904

(Monocot)

IC05 = 

0.00195 

lb a.i./A

Acceptable

Tomato

Lycopersicon 

esculentum 21 days

EC25 = 

0.139 lbs 

a.i./A

Fresh Weight

MRID 

49385904

(Dicot)

NOAEL 

=0.105 lbs 

a.i./A

(Acceptable)

Vegetative 

Vigor with 

TGAI

Sorghum

Sorghum 

vulgare 21 days

EC25 > 1.7 

lbs a.i./A

Shoot Length

MRID 

43465002

(Monocot)

NOAEL = 

0.43 lbs 

ai/A

(Acceptable)

Cotton

Cotton 21 days

EC25 = 

0.27 lbs 

a.i./A

Shoot Length

MRID 

42904201

(Dicot)

NOAEL = 

0.027 lbs 

a.i./A

(Acceptable)

Vegetative 

Vigor with 

GF-1742

Ryegrass

Lolium 

perenne 21 days

EC25 = 

0.212 lbs 

a.i./A

Fresh Weight MRID 

48915901 

(Acceptable) (Monocot)

NOAEL 

=0.053 lbs 

a.i./A

ND ND 21 days EC25>1.68 

lbs a.i./A ND
45

Exposure 

Scenario Species Scientific Name

Exposure 

Duration

Toxicity 

Reference 

Value

Effects

Reference

(Classification)

(Dicot)

NOAEL = 

1.68lbs 

a.i./A

Although ethalfluralin degrades to several minor degradates, they are not expected to be of 

environmental concern relative to the parent compound.

5.7 ECOTOX Open Literature

Open literature studies are identified using EPA’s ECOTOXicology database (ECOTOX) 

(USEPA, 2007c), which employs a literature search engine for locating chemical toxicity data 

for aquatic life, terrestrial plants, and wildlife. No additional data on ethalfluralin was identified 

through this review with endpoints more sensitive than those that were submitted.

5.8 Review of Incident Data

Incident reports submitted to EPA since approximately 1994 have been tracked by assignment of 

“incident numbers” in an Incident Data System (IDS), microfiched, and then entered into a 

second database, the Ecological Incident Information System (EIIS; USEPA 2007b). An effort 

has also been made to enter information to EIIS on incident reports received prior to 

establishment of current databases.

A preliminary review of the EIIS database indicates that there are 99 incidents involving 

terrestrial plants associated with the use of ethalfluralin since 1996. Incidents were reported in 

all seasons and resulted from both registered uses as well as occasional misuse of the product of 

both granular and emulsifiable (EC) formulations. The magnitude of damage ranged from a 

small area (1 acre) to the entire treated crop and over 800 acres. The incidents ranged from 

applications in all seasons (spring, summer, autumn and winter) from both granular and spray 

ground applications. These incidents are detailed in Table 19.

Table 19. Summary of Ecological Incidents as found in EIIS from the Usage of Ethalfluralin 

(Note: In every incident, the taxa affected were terrestrial plants).

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I013636-

042 2002 Registered 

use

Highly 

Probable ND Broadcast Sonalan®

Ethalfluralin was applied 

to dry beans in 2001, and 

then wheat was planted in 

2002. Carryover of 

ethalfluralin residues may 

have caused the injury 

due to extremely dry 

winter conditions 

following the harvest of 

the dry beans
46

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I009516-

003 1999 Registered 

Use Possible ND Broadcast Sonalan® HFP

Canola crop showed 

decreased growth and 

abnormal roots. Heavy 

rain and cold conditions 

were present shortly 

before application.

I010927-

021 2000 Registered 

Use Possible ND Spray Sonalan® HFP

707 acres of soybeans 

affected by crop stand 

loss, reported that cool 

wet soils were prevalent 

throughout area during 

the month and may have 

contributed

I014702-

067 2003 Registered 

use

Possible ND Broadcast Sonalan®

Damaged wheat crop 

resulting from carryover 

from sunflower 

application with severe 

drought conditions and 

minimal breakdown of 

Sonalan®

I008183-

001 1997 Undetermined Possible CA Broadcast Sonalan® HFP

Alleged damage of dry 

beans due to treatment, 

excess moisture may have 

also contributed

I012366-

006 2001 Registered 

use

Possible IL N/R Sonalan® EC

21 acres of damaged 

apple crops reported, 

unknown whether 

application of 

ethalfluralin was the 

cause

I012457-

016 2001 Undetermined Possible GA N/R Sonalan® --

I011444-

015 2001 Misuse 

(accidental) Possible GA N/R Sonalan®

There is no evidence that 

ethalfluralin was 

responsible for the fish 

kills reported

I010927-

025 1998 Undetermined Possible Canada N/R EDGE

Canola crop damaged 

when plant failed to 

emerge properly, a test 

conducted in June, 1998 

found ethalfluralin on 

canola at 0.58 ppm.

I011838-

067 2001 Undetermined Possible OK N/R Sonalan® --

I011838-

049 2001 Undetermined Possible GA N/R Sonalan® --

I007755-

023 1998 Registered 

Use Possible ND Soil 

incorporation Sonalan® HFP

Pre-plant incorporation on 

47 acres of wheat crop 

allegedly resulted in 

swollen roots and root 

hair growth
47

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I014702-

066 2003 Registered 

use

Possible ND Broadcast Sonalan® 10G

Carryover from canola 

application in 2002 

coupled with a severe 

drought led to damaged 

stand of durum wheat in 

2003

I008323-

001 1998 Undetermined Possible Canada N/R EDGE 

GRANULAR

Unknown if label 

directions followed, 

canola crop allegedly 

failed to emerge or 

germinate from seed

I011838-

038 2001 Undetermined Possible GA N/R Sonalan® --

I011838-

037 2001 Undetermined Possible GA N/R Sonalan® --

I011838-

036 2001 Undetermined Possible GA N/R Sonalan® --

I009516-

001 1999 Registered 

Use Possible TX Broadcast Sonalan® HFP

Application was a 

possible cause of damage, 

Dow Agrosciences 

inspector judged the 

peanut crop was diseased

I009516-

009 1999 Registered 

Use Possible ND Broadcast Sonalan® HFP

Dow inspector 

determined damage to 90 

acres of canola after soil 

sample analysis and plant 

inspection was more due 

to FARGO product than 

Sonalan®

I011838-

010 2000 Undetermined Possible GA N/R Sonalan® --

I007755-

017 1998 Registered 

Use Possible ND

PPI/GROUND/

Sonalan® 10G

570 acres in wheat crop 

allegedly demonstrated 

crop injury after 

application BROADCAST

I020627-

001 2000 Misuse Possible WA N/R N/R --

I009515-

002 1999 Registered use

Possible ND Broadcast Sonalan® 10G Stand reduction in canola 

crop reported

I014702-

071 2003 Registered 

use

Possible MN Broadcast Sonalan®

80 acres of canola 

damage allegedly due to 

application of 

ethalfluralin

I012457-

019 2001 Undetermined Possible GA N/R Sonalan® --

I011838-

066 2001 Undetermined Possible OK N/R Sonalan® --
48

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I009515-

001 1999 Misuse 

(accidental) Possible ND Soil 

incorporation Sonalan® 10G

Poor emergence of wheat 

reported but may have 

been due to soil that was 

inspected to be too wet 

for seeding

I013550-

001 2002 Registered 

use

Possible TX N/R Sonalan® HFP

Reported that a Sonalan 

tank may have been 

contaminated with some 

source of Picloram, which 

is not approved for 

peanuts

I011838-

045 2001 Undetermined Possible GA N/R Sonalan® --

I011838-

046 2001 Undetermined Possible GA N/R Sonalan® --

I011838-

040 2001 Undetermined Possible GA N/R PROWL --

I011838-

044 2001 Undetermined Possible GA N/R Sonalan® --

I009516-

002 1999 Registered 

Use Possible ND Broadcast Sonalan® HFP

Soybean crop showed 

decreased growth and 

abnormal roots. Heavy 

rain and cold conditions 

were present shortly 

before application.

I011838-

042 2001 Undetermined Possible GA N/R Sonalan® --

I011838-

048 2001 Undetermined Possible GA N/R Sonalan® --

I009516-

012 1999 Registered 

Use Probable MI Broadcast Sonalan® HFP

Damage to 180 acres of 

beans reported, adjacent 

area with no spraying 

showed no symptoms

I009516-

006 1999 Registered 

Use Probable ND Broadcast Sonalan® HFP Severe thinning of 30 

acres of canola reported

I009516-

011 1999 Registered 

Use Probable ND Broadcast Sonalan® HFP Thinning reported in 72 

acres of treated canola.

I009516-

007 1999 Registered 

Use Probable ND Broadcast Sonalan® HFP Severe thinning of 157 

acres of canola reported

I009516-

008 1999 Registered Use Probable ND Broadcast Sonalan HFP Severe thinning of 110 acres of canola reported

I009516-

004 1999 Registered Use Probable ND Broadcast Sonalan HFP Severe thinning of 100 acres of canola reported

I010927-

020 2000 Undetermined Probable ND N/R Sonalan® 10G

Determined by Dow 

inspector that ethalfluralin 

was applied a year before 

a mix of trifluralin and 

triallate, which is known 
49

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

to have damaging effects 

on wheat

I010927-

018 2000 Misuse 

(accidental) Probable ND Spray Sonalan® 10G --

I010927-

026 1999 Registered 

Use Probable Canada N/R EDGE

320 acres of canola crop 

damaged, AFC Agra 

Services Ltd., concluded 

ethalfluralin was 

responsible

I010927-

023 2000 Registered 

Use Probable ND Spray Sonalan® HFP

It was not determined 

whether the deep seeding, 

cold weather, or 

application of 

ethalfluralin that caused 

thinned canola stand

I012366-

003 2001 Registered 

use

Probable ND Broadcast Sonalan HFP

839 acres of canola saw 

severe crop thinning and 

poor emergence

I009510-

001 1999 Registered 

Use Probable IA Broadcast N/R Soybean crop allegedly 

damaged by application

I010927-

022 2000 Registered 

Use Probable ND Spray Sonalan® HFP

500 acres of canola stand 

was thinned compared to 

untreated area

I009516-

013 1999 Registered Use Probable ND Broadcast Sonalan® HFP Poor stand in 195 acres of canola reported

I006196-

012 N/R Registered 

Use Probable ID N/R Sonalan®

No analytical data 

included in report, 

damage to wheat reported 

after treatment

I009969-

001 1999 Registered 

Use Probable CA Broadcast Sonalan® HFP

Bean crop affected when 

hypocotyl was swollen 

following emergence, 

cold weather also may 

have been a factor

I009516-

010 1999 Registered 

Use Probable ND Broadcast Sonalan® HFP Thinning reported in 21 

acres of treated canola.

I010927-

016 2000 Misuse 

(accidental) Probable ND Spray Sonalan® 10G

This use was accidental as 

the product should not be 

used on wheat, it was 

what remained from an 

application the previous 

year

I010927-

017 2000 Misuse 

(accidental) Probable ND Spray Sonalan® 10G

This use was accidental as 

the product should not be 

used on wheat, it was 

what remained from an 

application the previous 

year
50

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I010927-

019 2000 Misuse 

(accidental) Probable ND Spray

Sonalan

® 10G

This use was accidental as 

the product should not be 

used on canola, it was 

what remained from an 

application the previous 

year

I012366-

005 2000 Registered 

use

Probable ND Broadcast Sonalan

® HFP

129 acres of soybeans 

showed poor emergence, 

stunted or slowed yield; a 

check strip showed a 

difference from treated 

vs. non-treated

I006197-

009 N/R Registered 

Use Probable ID N/R

Sonalan

® 10G

No analytical data 

included in report, 

abnormal growth reported 

in wheat crop after 

treatment

I006196-

009 N/R Registered 

Use Probable ID N/R

Sonalan

®

No analytical data 

included in report, 

damage to wheat reported 

after treatment

I006196-

003 N/R Registered 

Use Probable ND N/R

Sonalan

®

No analytical data 

included in report, 

reduced emergence 

reported in soybean crop 

after treatment

I006196-

004 N/R Registered 

Use Probable MN N/R

Sonalan

®

No analytical data 

included in report, 

reduced emergence 

reported in soybean crop 

after treatment

I006196-

005 N/R Registered 

Use Probable ND N/R

Sonalan

®

No analytical data 

included in report, slow 

emergence reported in 

soybean crop after 

treatment

I006196-

006 N/R Registered 

Use Probable ID N/R

Sonalan

®

No analytical data 

included in report, poor 

development of wheat 

crop after treatment

I003130-

001 1996 Registered 

Use Probable MT N/R

Sonalan

®® 10G

Spring crops following 

pesticide treatment 

demonstrated a thin stand

I006196-

007 N/R Registered 

Use Probable ID N/R

Sonalan

®

No analytical data 

included in report, 

damage to wheat reported 

after treatment

I006197-

011 N/R Registered 

Use Probable ID N/R

Sonalan

®10G

No analytical data 

included in report, 

abnormal growth reported 

in wheat crop after 

treatment
51

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I006197-

003 N/R Registered 

Use Probable ND N/R Sonalan®10G

No analytical data 

included in report, 

damage to wheat reported 

after treatment

I006454-

001 1997 Registered 

Use Probable MN N/R Sonalan®10 G The corn crop appeared 

stunted and pale in color

I009969-

002 1999 Undetermined Probable CA Broadcast Sonalan®HFP

100 acres of beans 

reported damaged, 

emergence of beans 

affected by tank mix of 

Sonalan®/DUAL

I014702-

070 2003 Registered 

use

Probable ND Broadcast Sonalan®

Damaged wheat crop 

resulting from carryover 

from sunflower 

application with severe 

drought conditions and 

minimal breakdown of 

Sonalan®

I014702-

068 2003 Registered 

use

Probable ND Broadcast Sonalan®

Damaged wheat crop 

resulting from carryover 

from sunflower 

application with severe 

drought conditions and 

minimal breakdown of 

Sonalan®

I013636-

045 2002 Registered 

use

Probable ND Broadcast Sonalan® HFP

Crop damage to beans 

determined to be due to 

seed cracks and a 

damaged embryonic shoot 

as well as cutworms

I013636-

046 2002 Registered 

use

Probable ND Broadcast Sonalan®

120 acres of canola 

reported damaged with 

thin stand, check strip 

indicated no damage

I014702-

069 2003 Registered 

use

Probable ND Broadcast Sonalan®

Damaged wheat crop 

resulting from carryover 

from application with 

severe drought conditions 

and minimal breakdown 

of Sonalan®

I016962-

037 2005 Registered 

Use Probable ND Band, 

incorporated Sonalan® HFP --

I013636-

043 2001 Registered 

Use Probable OR Broadcast Sonalan® HFP

Carryover of ethalfluralin 

application to dry beans 

from grass seed caused 

damage allegedly

I013636-

044 2000 Registered 

Use Probable OR Broadcast Sonalan® HFP

Carryover from dry beans 

in 2000 allegedly caused 

subsequent crops to be 

damaged
52

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I003146-

001 1996 Registered 

Use Probable MN N/R

Sonalan

® HFP

Treated soybean crop 

demonstrated disease, 

compaction, delayed 

emergence, and swollen 

hypocotyl

I006197-

004 N/R Registered 

Use Probable ND N/R

Sonalan

®10G

No analytical data 

included in report, thin 

stand of wheat reported 

after treatment

I012366-

004 2000 Registered 

Use Probable ND Broadcast Sonalan

® HFP

Soybeans in treated and 

untreated field had a 

difference in emergence, 

stand and yield

I009516-

005 1999 Registered 

Use Probable ND Broadcast

Sonalan

®HFP Severe thinning of 50 

acres of canola reported

I006196-

011 N/R Registered 

Use Probable ID N/R

Sonalan

®

No analytical data 

included in report, 

damage to wheat reported 

after treatment

I006196-

013 N/R Registered 

Use Probable MN N/R

Sonalan

®

No analytical data 

included in report, 

damage to sugar beets 

reported after treatment

I006196-

014 NR Registered 

Use Probable ND N/R

Sonalan

®

No analytical data 

included in report, non-

emergence of canola 

reported after treatment

I006196-

015 N/R Registered 

Use Probable WA N/R

Sonalan

®

No analytical data 

included in report, 

damage to dry bean crop 

reported after treatment

I006196-

016 N/R Registered 

Use Probable MN N/R

Sonalan

®

No analytical data 

included in report,

damage to corn crop 

reported after treatment

I004810-

001 N/R Registered 

Use Probable ND N/R

Sonalan

®10G

No analytical data 

included in report, 

reduced emergence 

reported in wheat crop 

after treatment

I006196-

001 N/R Registered 

Use Probable TX N/R

Sonalan

®

No analytical data 

included in report, reports 

that peanuts grown were 

stunted after exposure

I006196-

008 N/R Registered 

Use Probable ID N/R

Sonalan

®

No analytical data 

included in report, 

damage to wheat reported 

after treatment

I006196-

010 N/R Registered 

Use Probable ID N/R

Sonalan

®

No analytical data 

included in report, 

damage to wheat reported 

after treatment
53

Incident 

ID Year Legality Certainty State Application 

Method Product Comments

I006197-

005 N/R Registered 

Use Probable ND N/R Sonalan®10G

No analytical data 

included in report, poor 

emergence reported in 

wheat crop after treatment

I006197-

006 N/R Registered 

Use Probable ND N/R Sonalan®10G

No analytical data 

included in report, 

damage to wheat reported 

after treatment

I006197-

007 N/R Registered 

Use Probable ND N/R Sonalan®10G

No analytical data 

included in report, poor 

emergence reported in 

wheat crop after treatment

I006197-

008 N/R Registered 

Use Probable ID N/R Sonalan®10G

No analytical data 

included in report, 

abnormal growth reported 

in wheat crop after 

treatment

I006197-

010 N/R Registered 

Use Probable ID N/R Sonalan®10G

No analytical data 

included in report, 

abnormal growth reported 

in wheat crop after 

treatment

I004823-

001 1997 Registered 

Use Probable IL N/R Sonalan®HFP

Treatment allegedly 

rendered a crop that 

demonstrated thin stand, 

swollen hypocotyls, 

brown roots, and dying

I006197-

001 N/R Registered 

Use Probable ND N/R Sonalan®10G

No analytical data 

included in report, 

damage to oats reported 

after treatment

I006196-

002 N/R Registered 

Use Probable MN N/R Sonalan®

No analytical data 

included in report, reports 

that soybeans grown were 

stunted after exposure

I012366-

007 2001 Registered 

use

Probable MT N/R Sonalan®10G

56 acres of dry bean crop 

damaged due to weeds 

that were allowed to grow 

because of ineffective 

product

I006197-

002 N/R Registered

Use Probable ND N/R Sonalan®10G

No analytical data 

included in report, slow 

emergence reported in 

wheat crop after treatment

The Avian Monitoring Information System (AIMS), which is maintained by the American Bird 

Conservancy, indicates there are no incidents for wildlife. 

An absence of reported incidents should not be construed as the absence of incidents. Incident 

reports for non-target organisms typically provide information only on mortality events and plant 
54

damage incidents. Except for phytotoxic effects in terrestrial plants, sublethal effects, such as 

reduced growth or impaired reproduction, are rarely reported. EPA’s changes in the registrant 

reporting requirements for incidents in 1998 may account for a reduced number of reported 

incidents. Registrants are now only required to submit detailed information on ‘major’ fish, 

wildlife, and plant incidents. Minor fish, wildlife, and plant incidents, as well as all other nontarget incidents, are generally reported aggregately and are not included in the EIIS. In addition, 

there have been changes in state monitoring efforts due to a lack of resources. However, the 

incident data that are available suggest that exposure pathways for ethalfluralin are complete and 

that exposure levels are sufficient to result in field-observable effects for terrestrial plants.

6 Risk Characterization

Risk characterization is the integration of exposure and effects characterization to determine the 

potential ecological risk from the use of ethalfluralin and the likelihood of adverse effects on 

aquatic and terrestrial wildlife/plants based on varying pesticide-use scenarios. The risk 

characterization provides an estimation and a description of the risk; articulates risk assessment 

assumptions, limitations, and uncertainties; synthesizes an overall conclusion; and provides the 

risk managers with information to make regulatory decisions.

6.1 Risk Estimation

Results of the exposure modeling and toxicity effects data are used to evaluate the likelihood of 

adverse ecological effects on non-target species. For the assessment of ethalfluralin risks, the 

risk quotient (RQ) method is used to compare exposure and measured toxicity values (Table 20). 

The EECs are divided by the most sensitive acute and chronic toxicity values. The RQs are then 

compared to the Agency’s levels of concern (LOCs). These LOCs, summarized in Table 20, are 

the Agency’s interpretive policy and are used to analyze potential risk to non-target organisms 

and the need to consider regulatory action. These criteria are used to indicate when a pesticide’s 

use as directed on the label has the potential to cause adverse effects on non-target organisms. 
55

Table 20. Risk presumptions for terrestrial animals based on risk quotients (RQ) and levels of 

concern (LOC).

Risk Presumption RQ LOC

Birds

Acute Risk EEC1/LC50 or LD50/ft2 or LD50/day3 0.5

Acute Restricted Use EEC/LC50 or LD50/ft2 or LD50/day (or LD50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC50 or LD50/ft2 or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Wild Mammals

Acute Risk EEC/LC50 or LD50/ft2 or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/ft2 or LD50/day (or LD50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC50 or LD50/ft2 or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

1

 abbreviation for Estimated Environmental Concentration (ppm) on avian/mammalian food items 2

 mg/ft2

3

 mg of toxicant consumed/day

 LD50 * wt. of bird

 LD50 * wt. of bird 

Risk presumptions for aquatic animals based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Acute Risk EEC1/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Endangered Species EEC/LC50 or EC50 0.05

Chronic Risk EEC/NOAEC 1

1

 EEC = (ppm or ppb) in water

Risk presumptions for plants based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Terrestrial and Semi-Aquatic Plants 

Acute Risk EEC1/EC25 1

Acute Endangered Species EEC/EC05 or NOAEC 1

Aquatic Plants

Acute Risk EEC2/EC50 1

Acute Endangered Species EEC/EC05 or NOAEC 1

1

 EEC = lbs ai/A 

2 EEC = (ppb/ppm) in water 

6.2 Non-target Aquatic Animals and Plants
56

6.2.1 Acute Risk to Aquatic Animals

Acute RQs were derived for exposure of freshwater and estuarine/marine fish and invertebrates 

to ethalfluralin for application rates ranging from 0.75 lbs a.i. /A to 1.7 lbs a.i. /A (Table 21). 

Acute RQs for freshwater fish range from 0.11 to 0.39 and exceed the LOCs for acute risk to 

listed species (LOC=0.05) but not for non-listed species (LOC= 0.5). Similarly, acute RQs

ranging from 0.06 to 0.21 for freshwater invertebrates exceed the LOC for acute risk to listed

species. For estuarine/marine fish and invertebrates, the LOC for listed species is only exceeded 

at the highest application rate with RQs of 0.05 and 0.07 respectively. There are no LOC

exceedances for non-listed estuarine/marine species for any crop or application rate.

Table 21. Acute RQs for fish and aquatic invertebrates exposed to ethalfluralin.

Use App. 

Date

App. 

Rate 

lb/A

Peak

FW Fish FW 

Invert SW Fish SW Invert

FW 

Fish

FW 

Invert

SW 

Fish

SW 

Invert

LC50

(μg/L)

EC50

(μg/L)

LC50

(μg/L)

EC50

(μg/L) RQ RQ RQ RQ

Cucurbits 30-Oct 1.7 12.5 32 60 240 170 0.39a 0.21a 0.05a 0.07a

Cucurbits 30-Oct 0.75 5.52 32 60 240 170 0.17a 0.09a 0.02 0.03

Sunflower 10-Jun 1.7 5.91 32 60 240 170 0.18a 0.10a 0.02 0.03

Soybean 10-Oct 1.31 6.02 32 60 240 170 0.19a 0.10a 0.03 0.04

Peanut 1-May 1.15 4.12 32 60 240 170 0.13a 0.07a 0.02 0.02

Potatoes 10-

May 1.03 3.54 32 60 240 170 0.11a 0.06a 0.01 0.02

aBolded values denote that the RQ exceeds acute risk to listed species level of concern (LOC) of 0.05. The non-listed species LOC is 0.5.

6.2.2 Chronic Risk to Aquatic Animals

Chronic RQs were derived for exposure of freshwater fish and invertebrates and estuarine/marine 

invertebrates to ethalfluralin (Table 22). The chronic RQs for freshwater fish range from 1.0 to 

3.4 and exceed the chronic risk LOC (1.0) for every application rate and crop modeled. For 

estuarine/marine fish, the RQ only exceeds the LOC at the highest application rate with an RQ of 

1.13. None of the RQs (ranging from 0.03 to 0.15) for estuarine/marine and freshwater

invertebrates exceed the chronic risk LOC for any use or application rate modeled, 

Table 22. Chronic RQs for fish and aquatic invertebrates exposed to ethalfluralin.

Use

App. 

Rate 

lb/A

Estimated 

Environmental 

Concentration(μg/L)

SW 

Invert

FW 

Invert

SW 

Fish

FW 

Fish

SW 

Invert

FW 

Invert

SW 

Fish

FW 

Fish

NOAEC

(μg/L)

NOAEC

(μg/L)

NOAEC

(μg/L)

NOAEC

(μg/L) RQ RQ RQ RQ 21-day 60-day

Cucurbits 1.7 3.55 1.36 29.1 24 1.200 0.40 0.12 0.15 1.13a 3.40a

Cucurbits 0.75 1.57 0.6 29.1 24 1.200 0.40 0.05 0.07 0.50 1.50a
57

Sunflower 1.7 1.59 0.63 29.1 24 1.200 0.40 0.05 0.07 0.53 1.58a

Soybean 1.31 1.41 0.59 29.1 24 1.200 0.40 0.05 0.06 0.49 1.48a

Peanut 1.15 1.37 0.57 29.1 24 1.200 0.40 0.05 0.06 0.48 1.43a

Potatoes 1.03 1.01 0.4 29.1 24 1.200 0.40 0.03 0.04 0.33 1.00a

* Fish toxicity data are compared to the 60-day EEC while the invertebrate toxicity data are compared to the 21-day EEC. aBolded values indicate RQs exceeds, the chronic risk level of concern (LOC) of 1.0.

6.2.3 Risk to Sediment-dwelling Invertebrates

Chronic RQs were derived for freshwater sediment-dwelling invertebrates using both pore water

and sediment-based EECs and the toxicity endpoints for both Hyallela sp. and Chironomous sp. 

The sediment-based EECs are normalized to the organic carbon (OC) content of the sediment. 

The RQs based on pore water do not exceed the chronic risk LOC of 1.0 for any application rate 

or use modeled and are <0.01 in all cases (Table 23). The OC-normalized sediment-based RQs 

for Hyalella range from 1.3 to 4 and exceed the chronic risk LOC for all uses and application 

rates modeled (Table 24). The OC-normalized sediment-based RQs for Chironomous range 

from 0.13 to 0.4 and do not exceed the chronic risk LOC for any scenario modeled. There are no 

data available for the benthic estuarine/marine species of Leptocheirus. Although RQ values for 

the freshwater midges did not exceed the chronic risk LOC, those for Hyalella exceed the 

chronic risk LOC. Given the propensity of ethalfluralin to bind to the sediments, risk is 

presumed to estuarine/marine sediment-dwelling invertebrates (based on sediment OCnormalized EECs) until more information is received to permit evaluation of risks. 

Table 23. Porewater-based RQs for freshwater sediment-dwelling invertebrates.

Model 

Scenario

Use

Maximum 

Application 

rate

lbs a.i./A

Porewater 

EEC 

(μg/L)

Hyalella Chironomous Hyalella Chironomous

Porewater 

NOAEC

(μg/L)

Porewater 

NOAEC

(μg/L)

Porewater 

RQ

Porewater 

RQ 21-day

Cucurbits 1.7 0.33 92 270 <0.01 <0.01

Sunflower 1.7 0.28 92 270 <0.01 <0.01

Peanut 1.15 0.19 92 270 <0.01 <0.01

Potatoes 1.03 0.19 92 270 <0.01 <0.01

Table 24. Organic carbon normalized sediment based RQs for freshwater sediment 

dwelling invertebrates.

Model 

Scenario

Use

Maximum 

Application 

rate

lbs a.i./A

Sediment

EEC 

(μg/L)

Hyalella Chironomous Hyalella Chironomous

Sediment

(μg ai/KgOC)

Sediment

(μg ai/KgOC)

Sediment 

OC 

normalized 

RQ

Sediment 

OC 

normalized 

RQ

Sediment 

μg ai/KgOC

Cucurbits 1.7 1939.75 480 4800 4.04a 0.40

Sunflower 1.7 1117 480 4800 2.33a 0.23

Peanut 1.15 750 480 4800 1.56a 0.16

Potatoes 1.03 625 480 4800 1.30a 0.13
58

aBolded values indicate RQs exceeds, the chronic risk level of concern (LOC) of 1.0

6.2.4 Risk to Aquatic Plants

The RQs for non-listed vascular plants only exceed the LOC of 1.0 for the highest application 

rate modeled with an RQ of 1.7. The RQs for listed vascular plants range from 3.0 to 10.4 and 

exceed the LOC of 1.0 for every use and application rate modeled (Table 25). None of the RQs 

for non-vascular plants exceed the LOC of 1.0 for any application rate or use modeled with the 

exception of the RQ for listed non-vascular plants at the highest application rate. 

Table 25. RQs for non-vascular and vascular aquatic plants exposed to ethalfluralin.

Model 

Scenario

Use

Maximum 

Application 

rate

lbs a.i./A

EEC 

(μg/L)

Toxicity Values RQs

Non-Vascular 

Plant Vascular Plant Non-Vascular Plant Vascular Plant

Nonlisted

EC50

Listed

NOAEC

Nonlisted

EC50

Listed

NOAEC

Nonlisted Listed Nonlisted Listed

Peak

Cucurbits 1.7 12.5 25.30 10.90 7.30 1.20 0.5 1.1a 1.7b 10.4a

Cucurbits 0.75 5.52 25.30 10.90 7.30 1.20 0.2 0.5 0.8 4.6a

Sunflower 1.7 5.91 25.30 10.90 7.30 1.20 0.2 0.5 0.8 4.9a

Soybean 1.31 6.02 25.30 10.90 7.30 1.20 0.2 0.6 0.8 5.0a

Peanut 1.15 4.12 25.30 10.90 7.30 1.20 0.2 0.4 0.6 3.4a

Potatoes 1.03 3.54 25.30 10.90 7.30 1.20 0.1 0.3 0.5 3.0a

a Bolded RQ exceeds the risk to listed species LOC. bBolded RQ exceeds the risk to non-listed species LOC

6.3 Non-target Terrestrial Animals

6.3.1 Acute Risk to Birds and Mammals

Ethalfluralin is characterized as practically non-toxic to birds on both an acute oral and subacute 

dietary exposure basis. Avian acute toxicity tests did not have any observed mortality, and 

therefore no definitive toxicity values with the endpoints being greater than values of the highest 

doses tested. Therefore, avian acute RQs were not calculated. The acute endpoint for mammals 

is 5000 mg/kg (MRID 00135189) and is ethalfluralin is considered practically non-toxic to 

mammals on an acute oral exposure basis. None of the RQs exceed the LOC for either listed

species (LOC=0.1) or unlisted species (LOC=0.5). Acute risk to birds and mammals is not 

anticipated through either emulsifiable concentrate or granular formulations through registered 

uses of ethalfluralin. 

6.3.2 Chronic Risk to Birds and Mammals
59

Avian Species

The NOAEC in the chronic bird toxicity studies was 1,000 ppm, but no adverse effects were 

observed in these studies. The maximum acute EEC for the proposed uses is 462 ppm for 

residues on short grasses from the alfalfa use with an application rate of 1.69 lbs a.i. /A. 

Therefore, even if effects had been observed at the 1000 ppm level, RQ values would not exceed 

the chronic risk LOC of 1.0.

Mammalian Species

The previous assessment did not identify any chronic risk to mammals (DP# D205884, 

D296985, and D296987). The endpoint used in that assessment could not be confirmed for use 

in this assessment. Therefore, this assessment utilized the chronic toxicity value of 61 mg/kg bw 

based on reduced reproduction. Utilizing this endpoint, dose-based RQ values exceed the

chronic risk LOC; however, dietary-based RQ values for uses of emulsifiable concentrates do not 

exceed the chronic risk LOC (Table 26). RQs based on upper-bound Kenaga values ranged 

from 0.01 to 3.3. RQs for small- and medium-sized mammals (15 g and 35 g mammals,

respectively) exceed the chronic risk LOC of 1.0 for short grass, tall grass, broadleaf plants for 

uses on alfalfa, cucurbits, potatoes and sunflower with application rates that ranged from 1 to 

1.69 lbs a.i./A. RQs at the highest application rate of 1.69 also exceed the chronic risk LOC for 

mammals foraging on arthropods. RQs for large (1000 gram) mammals only exceed the chronic 

risk LOC of 1 for short grass for application rates greater than 1.3 lbs a.i./A. Chronic risk from 

dietary exposure was not identified for mammals at any application rate for spray formulations.

Table 26. Chronic dose-based RQs for mammals exposed to proposed spray uses of ethalfluralin.

15 gram "Small" Mammal 35 gram "Medium" Mammal 1000 gram "Large" Mammal

Use 

(application 

rate lbs a.i./A)

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Short Grass

Tall Grass

Broadleaf Plants

Fruits/pods

Arthropods

Seeds

Alfalfa with 

low broadcast 

spray (1.698)

2.9 1.3 1.6 0.2 1.1 0.0 2.5 1.1 1.4 0.2 1.0 0.0 1.3 0.6 0.7 0.1 0.5 0.0

Potatoes 

chemigation 

(1.028)

1.8 0.8 1.0 0.1 0.7 0.0 1.5 0.7 0.8 0.1 0.6 0.0 0.8 0.4 0.5 0.1 0.3 0.0

Sunflower 

(1.3) granular, 

incorporated,

chemigation

2.2 1.0 1.2 0.1 0.9 0.0 1.9 0.9 1.1 0.1 0.7 0.0 1.0 0.5 0.6 0.1 0.4 0.0

6.3.3 Risks to Piscivorous Birds and Mammals

Ethalfluralin has the ability to bioaccumulate/magnify in the aquatic food chain. In order to 

assess the magnitude of risk the KABAM model was used to predict the level of concern to 

higher trophic levels in aquatic food webs. The only LOC exceedance to piscivorous mammals 
60

feeding on fish containing ethalfluralin residues is from chronic exposure of the large river otter 

(RQ = 1.1) at the highest application rate of 1.69 lb ai/A. The RQs for the other mammals 

modeled ranged from 0.28 for water shrew to 0.7 for small river otter. The RQs for mammalian 

acute exposure do not exceed the acute risk LOC for any group at the highest application rate. 

The RQs for avian acute and chronic exposure feeding on fish containing ethalfluralin residues 

do not exceed acute or chronic risk LOCs at the highest application rate modeled (1.69 lbs ai/A). 

The one chronic RQ for mammals that exceeded the LOC at the 1.7 lbs ai/A level did not exceed 

the LOC at the next highest application rate modeled of 1.3 lbs ai/A. Ethalfluralin is expected to 

depurate in mammal tissues by 50% within three days ounces exposure stops. The KABAM 

model did not assume any depuration so the one exceedance is likely a worst case scenario and 

risk to piscivorous birds and mammals is likely low.

6.3.4 Risk to Non-target Terrestrial Plants

There were two new studies using a formulated end product that have been incorporated into the 

risk assessment for plants. The vegetative vigor study determined that monocots were more 

sensitive to formulated ethalfluralin than TGAI whereas dicots were more sensitive to TGAI than 

the formulated end product. The seedling emergence study with formulated end product had 

more sensitive endpoints for both monocots and dicots than the previous TGAI study. RQs were 

determined using the lowest available endpoint for both monocots and dicots in both the 

vegetative vigor and seedling emergence studies. The EC25 and NOAEC in the vegetative vigor 

studies were 0.212 and 0.053 lbs ai/A respectively for monocots and 0.27 and 0.027 respectively 

for dicots. The EC25 and NOAEC in the seedling emergence studies were 0.0183 and 0.00195 

lbs ai/A respectively for monocots and 0.139 and 0.105 respectively for dicots.

RQs resulting from off-site transport from runoff and spray drift of ethalfluralin are presented 

below. In general, monocots were more sensitive to ethalfluralin than dicots. 

Monocotyledon Species

RQs for monocots range from <0.1 to 130.7 (Table 27). RQs values for plants exposed to runoff 

and spray drift in semi-aquatic areas exceed the risk to non-listed and listed species LOCs for every 

use and application rate modeled. 

Table 27. Monocot RQs from applications of ethalfluralin in the modeled scenarios of 

Runoff and Spray Drift in Dry areas, Runoff and Spray Drift in Semi-Aquatic Areas, and 

Spray Drift only.

Use (application 

rate lbs a.i./A)

Monocot RQ Values

Runoff and 

Spray Drift 

(Dry Areas)

Runoff and 

Spray Drift

(Semi-Aquatic Areas)

Spray Drift Only

Nonlisted 

Species

Listed 

Species

Nonlisted 

Species

Listed 

Species

Nonlisted 

Species

Listed 

Species
61

Alfalfa, Beans with 

low broadcast spray 

EC1 (1.698)

1.86

b 17.44a 10.22b 95.90a 0.93 8.72a

Alfalfa, Beans with 

chemigation EC3 

(1.698)

5.57

b 52.31a 13.93b 130.77a 4.64b 43.59a

Beans granular 

(1.69) 0.92 8.67

a 9.23b 86.67a <0.1 <0.1

Clover 3" 

incorporated (1.5) 1.23

b 11.54a 4.92b 46.15a 0.82 7.69a

Cucurbits with low 

broadcast spray (1.7) 1.86

b 17.44a 10.22b 95.90a 0.93 8.72a

Dill ground spray 

(1.13) 0.93 8.69

a 3.70b 34.77a 0.62 5.79a

Lentils, Mustard 

granular formulation 

2" incorporation 

(0.95)

0.26 2.44

a 2.60b 24.36a <0.1 <0.1

Oilseed-Sunflower, 

Jojoba, etc (1.7) 

Granular 2 inch 

incorporation

0.46 4.36

a 4.64b 43.59a <0.1 <0.1

Oilseed-Sunflower, 

Jojoba, etc (1.7) 

Granular F 3 inch 

incorporation

0.17 1.62

a 1.73b 16.24a <0.1 <0.1

Oilseed-Sunflower, 

Jojoba, etc (1.7) EC3 

chemigation

5.57

b 52.31a 13.93b 130.7a 4.64b 43.59a

Oilseed – Crambe, 

Rapeseed (canola), 

etc. group (0.95) 

EC2 spray with 2 

inch incorporation

0.78 7.31

a 3.11b 29.23a 0.52 4.87a

Oilseed – Crambe, 

Rapeseed (canola), 

etc. group (0.95) G 

with 2 inch 

incorporation

0.26 2.44

a 2.60b 24.36a <0.1 <0.1

Oilseed-Safflower 

(1.15) granular with 

2 inch incorporation

0.31 2.95

a 3.14b 29.49a <0.1 <0.1

Peanuts granular 

formulation (1.15) 

with 2 inch 

incorporation

0.31 2.95

a 3.14b 29.49a <0.1 <0.1

Peanuts EC with 2 

inch incorporated 

(1.15)

0.94 8.85

a 3.77b 35.38a 0.63 5.90a

Peas EC (0.75) 2 

inch incorporation 0.61 5.77

a 2.46b 23.08a 0.41 3.85a

Peas granular 

formulation (0.75) 2 

inch incorporation

0.20 1.92

a 2.05b 19.23a <0.1 <0.1
62

Potatoes chemigation 

(1.028) 3.37 b 31.63a 8.43 b 79.08a 2.81 26.36 a

Potatoes ground 

(1.028) 0.84 7.91a 3.37 b 31.63a 0.56 5.27 a

Soybeans Granular 

(1.3) 2 inch 

incorporation

0.36 3.33a 3.55 b 33.33a <0.1 <0.1

a Bolded RQ exceeds the risk to listed species LOC. bBolded RQ exceeds the risk to non-listed species LOC

Dicotyledon Species

RQs for dicots ranged from <0.01 to 2.43 (Table 28). RQs for only six of the twenty uses exceeded 

the LOC for listed and non-listed dicot species. Application rates for these uses ranged from 1 to 

1.7 lbs a.i. /A. 

Table 28. Dicot RQs from applications of ethalfluralin in the modeled scenarios of Runoff and 

Spray Drift in Dry areas, Runoff and Spray Drift in Semi-Aquatic Areas, and Spray Drift only.

Use (application 

rate lbs a.i./A)

Dicot RQ Values

Runoff and 

Spray Drift 

(Dry Areas)

Runoff and 

Spray Drift

(Semi-Aquatic Areas)

Spray Drift Only

Nonlisted 

Species

Listed 

Species

Nonlisted 

Species

Listed 

Species

Nonlisted 

Species

Listed 

Species

Alfalfa, Beans 

with low 

broadcast spray 

(1.698)

0.24 0.32 1.35 b 1.78a 0.12 0.16

Alfalfa, Beans 

with chemigation 

EC3 (1.698)

0.73 0.97 1.83 b 2.43a 0.61 0.81

Beans granular 

(1.69) 0.12 0.16 1.22 b 1.61a <0.1 <0.1

Clover 3" 

incorporated (1.5) 0.16 0.21 0.65 0.86 0.11 0.14

Cucurbits with 

low broadcast

spray (1.7)

0.24 0.32 1.35 b 1.78a 0.12 0.16

Dill ground spray 

(1.13) 0.12 0.16 0.49 0.65 <0.1 0.11

Lentils granular 

formulation 2" 

incorporation 

(0.95)

<0.1 <0.1 0.34 0.45 <0.1 <0.1

OilseedSunflower, 

Jojoba, etc (1.7) 

Granular 2 inch 

incorporation

<0.1 <0.1 0.61 0.81 <0.1 <0.1
63

Use (application 

rate lbs a.i./A)

Dicot RQ Values

Runoff and 

Spray Drift 

(Dry Areas)

Runoff and 

Spray Drift

(Semi-Aquatic Areas)

Spray Drift Only

Nonlisted 

Species

Listed 

Species

Nonlisted 

Species

Listed 

Species

Nonlisted 

Species

Listed 

Species

OilseedSunflower, 

Jojoba, etc (1.7) 

Granular F 3 inch 

incorporation

<0.1 <0.1 0.23 0.30 <0.1 <0.1

OilseedSunflower, 

Jojoba, etc (1.7) 

EC3 chemigation

0.73 0.97 1.83b 2.43a 0.61 0.81

Oilseed –

Crambe, 

Rapeseed 

(canola), etc. 

group (0.95) EC2 

spray with 3 inch 

incorporation

0.10 0.14 0.41 0.54 <0.1 <0.1

Oilseed –

Crambe, 

Rapeseed 

(canola), etc. 

group (0.95) G 

with 2 inch 

incorporation

<0.1 <0.1 0.30 0.45 <0.1 <0.1

Oilseed-Safflower 

(1.15) granular 

with 2 inch 

incorporation

0.10 0.14 0.41 0.54 <0.1 <0.1

Peanuts granular 

formulation (1.15) 

with 2 inch 

incorporation

0.10 0.14 0.41 0.54 <0.1 <0.1

Peanuts EC with 2 

inch incorporated 

(1.15)

0.12 0.16 0.50 0.66 <0.1 0.11

Peas EC (0.75) 2 

inch incorporation <0.1 0.11 0.32 0.43 <0.1 <0.1

Peas granular 

formulation (0.76) <0.1 <0.1 0.30 0.40 <0.1 <0.1

Potatoes 

chemigation 

(1.028)

0.44 0.59 1.11b 1.47a 0.37 0.49

Potatoes ground 

(1.028) 0.11 0.15 0.44 0.59 <0.1 <0.1

Soybeans 

Granular (1.3) 2 

inch incorporation

<0.1 <0.1 0.47 0.62 <0.1 <0.1

a Bolded RQ exceeds the risk to listed species LOC.
64

b Bolded RQ exceeds the risk to non-listed species LOC

6.3.5 Risk to Terrestrial Invertebrates

Bees may be exposed to ethalfluralin via direct applications, drift from boom or aerial spray, or 

from residues on plants adjacent to treated fields. There are no acute or chronic toxicity studies 

submitted for larval bees or any acute oral or chronic toxicity studies for adult bees. Therefore, 

RQs resulting from contact exposure to ethalfluralin residues are presented in Table 29. The 

RQs are less than values because the toxicity endpoint did not show any toxicity at the highest 

concentrations tested. 

Table 29. Contact RQs for bees that result from applications of ethalfluralin.

Use (application rate lbs a.i./A) Contact 

Exposure

Alfalfa with low broadcast spray (1.698) <1.1

Cucurbits with low broadcast spray (1.932) <1.2

Potatoes chemigation (1.028) <0.6

Sunflower (1.3) granular, incorporated, 

chemigation <0.8

Using calculations from Bee-Rex modeling, the RQs for contact range from <0.6 to <1.2 which, 

based on absolute value, exceed the Agency’s established acute risk LOC of 0.4. The acute 

contact toxicity study did not indicate any adverse effects at the highest concentration tested of 

51 μg/bee, and ethalfluralin is classified as practically non-toxic to adult bees on an acute contact 

exposure basis. The RQs generated are thus the result of non-definitive toxicity estimate and the 

high application rates leading EECs that range from 33 μg/bee to 61 μg/bee. There is significant 

uncertainty in these acute RQs as well as the lack of data on chronic effects. The extent of 

exposure is uncertain as well since pre-plant timing of application may reduce exposure to 

pollinators if early in the growing season when plants are not flowering. If the acute oral 

endpoint was similar to that of the contact study (>51 μg/bee) which was practically non-toxic,

RQs would range from <0.05 to <0.1. 

7 Risk Description

7.1 Risk to Non-Target Aquatic Organisms

Ethalfluralin is applied as both a spray (physically incorporated or wetted in) and in granular 

form and non-target aquatic taxa may come into contact with ethalfluralin as a result of spray 

drift or runoff. Ethalfluralin may still however reach water bodies due to runoff but the high 

organic carbon partition coefficient suggests an affinity to bind to sediment thereby decreasing 

water column concentrations. Additionally, ethalfluralin concentrations in surface water should 

be limited by its susceptibility to photolysis in water (half-life = 6.3 hours) but is somewhat more 

persistent in turbid waters and in low light environments. 
65

Aquatic Animals

The acute studies with freshwater and estuarine/marine fish and invertebrates using TGAI

indicate that ethalfluralin is very highly toxic to estuarine/marine fish, freshwater fish, and 

freshwater invertebrates, and is highly toxic to estuarine/marine invertebrates on acute exposure

basis. The EECs result in RQs for freshwater taxa that exceed LOC for acute risk to listed

species but not for non-listed species. The LOC for acute risk to listed estuarine/marine species

is only exceeded at the highest concentration modeled and RQs do not exceed the acute risk to

non-listed LOC. 

To further analyze the potential risk from ethalfluralin use to aquatic species, the AgDrift model 

was used to predict spray drift deposition, and to determine the distance from the edge of the 

treated site where the risk from spray drift alone is equal to the LOC for acute risk to listed and 

non-listed aquatic species. It is important to recognize, though, that risk from runoff is not 

considered in this analysis. Elimination of spray drift may reduce the impact to water column 

taxa as demonstrated by Table 30 and Table 31. Effects distances, defined as the distance 

within which spray drift may adversely affect water column taxa ranged from 3 feet to 65 feet for 

listed species when using a low boom and high boom, respectively, with very fine to fine droplet 

sizes. Increasing the droplet sizes to fine or medium coarse (median droplet size of 341 μm) 

reduces the effect distance to 0 (Table 31.)

Table 30. Buffer distances for aquatic taxa using very fine to fine droplet sizes.

Aquatic Animals

Use 

(application 

rate lbs 

a.i./A)

Application 

Method

EFFECTS DISTANCES 

Very fine to fine Droplet sized 

(175 μm)

High boom (1.27 

m)

Low Boom (0.5

m height)

Nonlisted Listed Nonlisted Listed

1.69 / 1.7 Ground 0 65 0 7

1.5/1.52 Ground 0 53 0 3

1.15/1.13 Ground 0 33 0 3

1.0/ 0.95 Ground 0 23 0 0

Freshwater Fish LC50 32 μg a.i./A; 

Table 31. Buffer distances for aquatic taxa using fine to medium coarse droplet sizes.

Aquatic Animals

Use 

(application 

rate lbs 

a.i./A)

Application 

Method

EFFECTS DISTANCES

Fine to Medium Coarse Droplet 

sized (341 μm)

High boom (1.27 

m)

Low Boom (0.5

m height)
66

Nonlisted Listed Nonlisted Listed

1.69 / 1.7 Ground 0 0 0 0

1.5/1.52 Ground 0 0 0 0

1.15/1.13 Ground 0 0 0 0

1.0/ 0.95 Ground 0 0 0 0

Freshwater Fish LC50 32 μg a.i./A; 

The RQs for freshwater fish exceed the chronic risk LOC at application rates of 1 lb ai. /A and 

higher. The RQs for estuarine/marine fish exceed the chronic risk LOC only at the highest 

application rate while the RQs for invertebrates in either freshwater or estuarine/marine

environments do not exceed the chronic risk LOC at any of the application rates modeled. Based 

on the available data, there is potential for acute and chronic risks to aquatic animals. Additional

potential for indirect effects to these species also exist because of the risk to aquatic plants (see 

below). Many aquatic animals are directly and/or indirectly dependent upon aquatic plants for 

food and/or shelter during various life-stages.

Ethalfluralin has a high propensity to bind to sediment particles. While this property may reduce 

chronic risk to water column taxa, RQs indicate that freshwater sediment-dwelling invertebrates 

may be at risk. Chronic RQs derived from 10-day toxicity tests for Hyalella sp. range from 1.3 to 

4 and exceed the chronic risk LOC at all of the application rates modeled; however, the RQs 

based on a 10-day toxicity test with Chironomous range from 0.13 to 0.4 and do not exceed the 

chronic risk LOC. For both freshwater species, the sub-chronic 10-day test is often less sensitive 

than the full 28-day chronic test. Thus these RQs may represent lower-bound estimates of risk 

and in order to more fully understand risk to sediment-dwelling invertebrates, a 28-day chronic 

toxicity test may be needed. Additionally, a sediment toxicity test with an estuarine/marine 

species was not submitted. Until these data are available, potential risk to estuarine/marine 

sediment-dwelling invertebrates is presumed when they are exposed to ethalfluralin on a chronic 

basis.

Aquatic Plants

Based on data and the predicted aquatic exposures, the likelihood of adverse effects on non-listed 

species non-vascular aquatic plants is considered low; however, at the highest application rate, 

the RQ for listed non-vascular plants exceeds the LOC. Similarly, the only LOC exceedance for 

non-listed vascular plants is at the highest application rate modeled. RQ values exceed the 

LOC for risk to listed vascular plants at all application rates modeled (RQs 3 – 10; Table 25). 

The contribution of spray drift to the overall risk to aquatic plants may be effectively mitigated 

by adjusting the boom height and droplet sizes to minimize impacts from spray drift. The 

distance from aquatic water bodies that ethalfluralin may be applied without adversely impacting 

aquatic plants is reduced from 59 feet to 7 feet for listed species by lowering the boom height 

when using the highest application rates (Table 32). This effect distance dropped to zero from 

increasing the droplet size for all scenarios modeled (Table 33). 
67

Table 32. Buffer distances from spray applications with very fine to fine droplet sizes.

Aquatic Plants

Use 

(application 

rate lbs 

a.i./A)

Application 

Method

Effects Distances

Very fine to fine Droplet sized (175 

μm)

High boom (1.27 

m)

Low Boom (0.5 m 

height)

Nonlisted Listed Nonlisted Listed

1.69 / 1.7 Ground 0 59 0 7

1.5/1.52 Ground 0 46 0 3

1.15/1.13 Ground 0 26 0 3

1.0/ 0.95 Ground 0 20 0 0

L. gibba LC50 7.3 μg a.i./A; NOAEC = 1.7 μg ai/A

Table 33. Buffer distances from spray applications with fine to medium/coarse droplet 

sizes.

Aquatic Plants

Use 

(application 

rate lbs 

a.i./A)

Application 

Method

Effects Distances

Fine to Medium Coarse Droplet sized 

(341 μm)

High boom (1.27 

m)

Low Boom (0.5 m 

height)

Nonlisted Listed Nonlisted Listed

1.69 / 1.7 Ground 0 0 0 0

1.5/1.52 Ground 0 0 0 0

1.15/1.13 Ground 0 0 0 0

1.0/ 0.95 Ground 0 0 0 0

L. gibba LC50 7.3 μg a.i./A; NOAEC = 1.7 μg ai/A

7.2 Risk to Non-Target Terrestrial Organisms

The magnitude and duration of adverse effects resulting from acute and chronic exposure via 

intake of ethalfluralin residues for birds and mammals is discussed below. The likelihood of 

exposure is increased given the moderate persistence of ethalfluralin in terrestrial environments

(half-lives ranging between 23–51 days). 

Birds 

• Acute Risk (Oral-based)
68

Based on the submitted acute oral toxicity studies on birds, ethalfluralin is categorized as 

practically non-toxic to birds on an acute oral exposure basis. An oral toxicity test with a 

passerine species was recently provided; based on this study ethalfluralin is practically non-toxic

to passerines and these data are similar to results for mallard duck (Anas platyrhynchos) and 

bobwhite quail (Colinus virginianus). Similar to the previous assessment, no risk identified for 

birds on an acute oral exposure basis from either granular or emulsifiable concentrate

formulations. 

• Chronic Risk (Dietary-based)

The NOAEC in the chronic bird toxicity studies was 1,000 ppm, but no adverse effects were 

observed in these studies. The maximum EEC for the proposed uses would be 406 ppm for short 

grass residues from the alfalfa use. Therefore, even if effects had been observed at the 1000 ppm 

level, chronic risks would not be expected.

Since birds serve as surrogates for terrestrial-phase amphibians and reptiles, the low likelihood of 

adverse effects on birds from either acute or chronic exposure to ethalfluralin extends to these 

taxa as well.

Mammals

• Acute Risk (Oral-based)

Ethalfluralin is practically non-toxic to mammals on an acute oral exposure basis. There are no 

acute risk LOC exceedances for any application rates for either emulsified concentrate or granular 

formulations. Therefore, the likelihood of adverse effects to mammals from acute exposure to 

ethalfluralin is considered low.

• Chronic Risk (Dose and Dietary-based)

Dose-based RQ values are above the chronic risk LOC for all size classes of mammals for 

unincorporated uses on alfalfa, cucurbits, potatoes, and sunflower with application rates of 1.3 

lbs. a.i. or higher. RQs range from 1.0 (for large mammals feeding on short grass exposed to the 

lowest application rate) to 3.3 for small mammals feeding on short grass at the highest 

application rate of 1.69 lbs a.i. /A. For small- and medium-sized mammals, RQ values exceed 

the chronic risk LOC for short grass, tall grass, broadleaf plants and arthropods (Table 26). 

These chronic risk estimates differ from the previous assessment as a result of a new endpoint 

(NOAEC = 61 mg/kg-bw based on reproductive effects; MRIDs 43868313 and 44073701) and 

higher application rates. To provide a lower bound to the estimates of risk to mammals resulting 

from chronic exposure to ethalfluralin, RQs using mean Kenaga residue values in addition to 

upper-bound values were calculated. Using the non-conservative mean residue values, implying 

that higher predicted residue values are expected half the time, chronic dose-based RQs only 

exceed the chronic risk LOC of 1.0 for small mammals feeding on short grass at the highest 
69

application rates modeled (i.e., 1.69 lbs ai/A). RQs calculated using mean Kenaga values exceed 

the dose-based chronic risk LOC only for small mammals feeding on short grass exposed the 

highest application rate (RQ =1.02). Using mean Kenaga values did not result in any other RQs 

that exceeded the LOC. Consistent with the previous assessment, dietary-based RQ values do 

not exceed that chronic risk LOC.

Piscivorous Birds and Mammals

The only LOC exceedance to piscivorous mammals feeding on fish containing ethalfluralin 

residues is from chronic exposure of the large river otter (RQ = 1.1) at the highest application

rate of 1.69 lb ai/A. The RQs for the other mammals modeled range from 0.28 for water shrew 

to 0.7 for small river otter. The RQs for mammalian acute exposure do not exceed the acute risk

LOCs for any group at the highest concentration rate. The RQs for birds based on acute and 

chronic exposure from feeding on fish containing ethalfluralin residues do not exceed either the 

acute or chronic risk LOCs at the highest application rate modeled (1.7 lbs ai/A). The one 

chronic RQ for mammals that exceeds the LOC at the 1.7 lbs ai/A level does not exceed the LOC 

at the next highest application rate modeled (1.3 lbs ai/A). While ethalfluralin’s log Kow is 5.11,

suggesting the potential for ethalfluralin residues to partition into fatty tissues, bioconcentration 

studies suggest that the compound is rapidly metabolized (MRID 41994902) and excreted 

(depurated) once exposure ceases. The BCF ranged from 1330 μg/L in whole fish to 1560 μg/L 

in muscle with a depuration half-life of three days after exposure ceased (MRID 41994902). The 

BCF predicted by the KABAM model ranged from 5889 μg/L to 6191 μg/L for small and large 

fish respectively without any metabolism of ethalfluralin. Ethalfluralin is expected to depurate by 

50% within 3 days once exposure is stopped making the estimates from the KABAM model 

highly conservative. The metabolism of ethalfluralin, coupled with low acute toxicity to birds 

and mammals, suggest the potential for adverse effects from acute or chronic exposure to

ethalfluralin residues in fish is relatively low except for large mammals where the chronic risk 

LOC is exceeded at the maximum application rate of 1.69 lbs a.i./A. 

Terrestrial Invertebrates

Results of the acute contact toxicity studies with honey bees demonstrate that ethalfluralin TGAI 

is practically non-toxic to beneficial insects on an acute contact exposure basis (LD50 >51 μg a.i. 

/bee). While the absolute value of RQs for acute risk is above the acute risk LOC of 0.4, all the 

actual values are less than values since the acute contact study did not achieve a definitive LD50. 

Toxicity data for chronic exposure of adult and larval honeybees to ethalfluralin as well as acute 

exposure to larval honeybees are not available; therefore, there is more uncertainty as to the

potential risk to these castes from other exposure routes to ethalfluralin. 

Terrestrial Plants

• Runoff and Spray Drift Exposure

Based on the seedling emergence test with terrestrial plants, ethalfluralin is more toxic to 

monocots than to dicots. The EC25 and NOAEC in the seedling emergence tests are 0.0183 lbs 

ai/A and 0.00195 lbs ai/A, respectively, for monocots versus 0.139 lbs ai/A and 0.105 lbs ai/A,
70

respectively, for dicots. In contrast to the seedling emergence toxicity tests, ethalfluralin is less 

toxic to both monocots and dicots in vegetative vigor tests. The EC25 and NOAEC in the 

vegetative vigor tests are 0.212 lbs ai/A and 0.053 lbs ai/A, respectively, for monocots and 0.27 

lbs ai/A and 0.027 lbs ai/A, respectively, for dicots. Current terrestrial phytotoxicity data and the 

predicted exposures from the TerrPlant model indicate potential risk to non-listed and listed 

monocot and dicot terrestrial and semi-aquatic plant species. Monocot RQs range from 2 to 130 

in semi-aquatic areas; dicot RQs range from 0.2 to 2.4 in semi-aquatic areas. 

To further analyze the potential risk from ethalfluralin use to non-target plants, the AgDrift 

model was used to predict spray drift deposition, and to determine the distance from the edge of 

the treated site where the risk from spray drift alone is equal to the LOC for listed and non-listed 

plants. Beyond these distances, the risk from spray drift alone is not expected to exceed the 

LOC. Table 34 and Table 35 provide effects distances for both monocots and dicots 

respectively using the default droplet size distributions in the AgDRIFT model for ground 

applications (droplet sizes per the American Society of Agricultural and Biological Engineers or 

ASABE: very fine to fine for ground applications). This is done since ethalfluralin labels do not 

specify droplet size distributions. Ground applications are modeled with both high and low 

boom applications (1.27 and 0.5 meters above the ground respectively). 

For monocots, spray drift effects distances resulting from low boom ground applications range 

from 7 feet for non-listed species at the lowest application rate, to 30 feet for listed species 

exposed to the highest application rates (Table 34). These spray drift effects distances increase 

for high boom applications and range from 13 feet for non-listed species at the lowest application

rate to 82 feet for listed species at the highest application rate. 

Table 34. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive 

monocot species for applications with very fine to fine droplet size spectrum (ground 

applications). 

Monocot Effects Distances

Use 

(application 

rate lbs 

a.i./A)

Application 

Method

BUFFER DISTANCES for ground application

Very fine to fine Droplet Size (175 μm)

High boom (1.27 m) Low Boom (0.5 m height)

Non-listed Listed Non-listed Listed

1.69 / 1.7 Ground 23 82 10 30

1.5/1.52 Ground 20 72 10 26

1.15/1.13 Ground 16 56 7 20

1.0/ 0.95 Ground 13 49 7 20

MONOCOT EC25 0.212; NOAEC 0.053

Table 35. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive 

dicot species for applications with very fine to fine droplet size spectrum (ground 

applications)

Dicot Buffer Distances

Buffer distances for ground application
71

Use (application 

rate lbs a.i./A)

Application 

Method

Very fine to fine Droplet Size (175 μm)

High boom (1.27 m) Low Boom (0.5m height)

Non-listed listed Nonlisted listed

1.69 / 1.7 Ground 20 157 7 59

1.5/1.52 Ground 16 141 7 49

1.15/1.13 Ground 13 108 7 39

1.0/ 0.95 Ground 10 95 7 33

DICOT EC25 0.27; NOAEC 0.027

For dicots, spray drift effect distances that result from low boom ground applications range from 

7 feet for non-listed species at the lowest application rate to 59 feet for listed species exposed to 

the highest application rates (Table 35). These effect distances increase for high boom 

applications and range from 10 feet for non-listed species at the lowest application rate to 157

feet for listed species at the highest application rates. 

Table 36. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive 

monocot species for applications with fine to medium coarse droplet sizes (ground 

applications).

Monocot Buffer Distances

Use 

(application 

rate lbs 

a.i./A)

Application 

Method

BUFFER DISTANCES for Coarse droplet sizes for ground 

application

Fine to Medium Coarse Droplet Size (341 μm)

High boom (1.27 m) Low Boom (0.5 m height)

Non-listed Listed Non-listed Listed

1.69 / 1.7 Ground 7 16 3 10

1.5/1.52 Ground 3 16 3 10

1.15/1.13 Ground 3 13 3 7

1.0/ 0.95 Ground 3 10 3 7

MONOCOT EC25 0.212; NOAEC 0.053

Table 37. Modeled spray drift buffer distances needed to mitigate risk to the most sensitive dicot 

species for applications with fine to medium coarse droplet sizes (ground applications).

Dicot Buffer Distances

Use 

(application 

rate lbs 

a.i./A)

Application 

Method

BUFFER DISTANCES for Coarse droplet sizes for 

ground application

Fine to Medium Coarse Droplet Size (341 μm)

High boom (1.27 m) Low Boom (0.5 m height)
72

Non-listed Listed Non-listed Listed

1.69 / 1.7 Ground 3 36 3 20

1.5/1.52 Ground 3 33 3 20

1.15/1.13 Ground 3 23 3 13

1.0/ 0.95 Ground 3 20 3 13

DICOT EC25 0.27; NOAEC 0.027

The AgDRIFT model was also run with the coarsest droplet sizes for ground applications in 

order to evaluate spray drift buffer distances with larger droplet sizes which may be more 

common with pre-emergent herbicide applications and to explore the narrowest buffers possible 

to mitigate the risks due to spray drift with the current ethalfluralin uses. The spray drift buffer 

distances required to mitigate risk for ground applications with fine to medium/coarse droplet 

sizes (DV0.5 droplet size = 341 microns) with a low boom range from 3 feet for non-listed 

monocot species to 10 feet for listed monocot species at the lowest and highest application rates 

respectively (Table 36). The buffer distances required to mitigate risk for ground applications 

with a low boom range from 3 feet for non-listed dicot species to 20 feet for listed dicot species 

at the lowest and highest application rates, respectively (Table 37). Buffer distances are also 

provided for a high boom scenario as well since labels often say to position height of boom for 

uniform coverage but to limit drift. 

8 Uncertainties, Data Gaps, Assumptions, and Limitations

• Environmental Fate

The environmental fate database for ethalfluralin is essentially complete with no major data gaps 

identified. However, some of the aerobic soil metabolism studies have been determined to be 

supplemental and resolution of the study uncertainties could increase the confidence regarding 

the persistence of ethalfluralin in aerobic soils. Overall, besides these uncertainties, the available 

data give a largely complete picture of a herbicide with moderate environmental persistence 

(generally persisting for weeks to months), and moderately high volatility, strong soil / sediment

sorption and partitioning into organic material.

• Ecological Effects and Data Gaps.

The ecological effects data are largely complete with the exception of a chronic toxicity test for 

estuarine/marine benthic invertebrates and additional pollinator studies. There is a high degree of 

uncertainty regarding risk to bees due to a non-definitive endpoint and no adverse effects at the 

highest concentration tested in the acute contact study with adult bees. There are no acute or

chronic toxicity studies submitted for larval bees or any acute oral or chronic toxicity studies for 

adult bees. Additionally risk was identified for freshwater sediment invertebrates but a similar 

study was not submitted. 
73

Data gaps for this chemical are listed below: feeding studies for adult bees. In the absence of this 

data, risk is presumed in these compartments as well.

1. Whole sediment toxicity testing with an estuarine/marine sediment dwelling invertebrate

(Guideline 850.1735)

2. Tier 1 Acute oral toxicity to adult honeybees (Non-guideline; OECD 213)

3. Tier 1 Acute oral toxicity to larval honeybees (Non-guideline; OECD 237)

4. Tier 1 Chronic oral toxicity to adult honey bees (Non-guideline)

5. Tier 1 Chronic oral toxicity to larval honey bees (Non-guideline)

6. Tier 2 Pollinator feeding/semi-field study - The need for these studies is contingent upon 

the results of lower tier bee studies (Non-guideline)

7. Tier 2 Pollen and nectar residue studies – The need for these studies is contingent upon 

the results of lower tier bee studies (Non-guideline)

8. Tier 2 Field testing for pollinators – The need for field testing is contingent upon the 

results of lower tier bee studies (850.3040)

In the absence of this data, risk is presumed in these compartments as well.

• Aquatic Exposure

In general, upper-bound aquatic exposure estimates for ethalfluralin presented in this risk 

assessment are sufficiently conservatively reflect exposure under the most vulnerable conditions 

in high use areas. Monitoring data taken from sites without intensive ethalfluralin usage suggest

low aquatic exposure to dissolved ethalfluralin with concentrations almost always below 0.1 ppb.

Also relevant to the level of confidence in the aquatic exposure estimates is the low usage 

profile, which has been on the decline in recent years. For example, the most recent annual usage 

level is estimated to be less than 1.4 million pounds of active ingredient over the entire United 

States in 2013. The usage is spread over a large portion of U.S. agricultural lands but at 

relatively low intensities, with nearly all reporting districts showing overall usage intensities 

below about 0.05 lb ai / acre. Aquatic environmental exposures, by contrast were modeled as a 

100% of the watershed at maximum label rates, making upper bound exposures highly 

conservative. 

• Terrestrial Exposure

Toxic response is a function of duration and intensity of exposure. For many compounds, an oral

dose represents a very short-term high intensity exposure. Although the dose-based estimates 

may not reflect reality in that animals do not receive a bolus dose while feeding, it is possible 

that a short-duration, high-intensity exposure could occur associated with feeding on an 

agricultural field since many birds may gorge themselves when food items are available. While 

the dietary-based estimates may suggest greater “realism,” they too suffer from some 

uncertainties. Primarily, the dietary-based approach assumes that animals in the field are 

consuming food at a rate similar to that of confined laboratory animals despite the fact that 

energy content in food items differs between the field and the laboratory as does the energy 

requirements of wild and captive animals.
74

Other uncertainties with ethalfluralin are related to the representativeness of T-REX with preemergent applications. Risks indicated by T-REX due to ethalfluralin residues on seeds or 

arthropods located within treated fields are most certain with its pre-emergent applications. 

However, for risks related to broadleaf plants which may be a surrogate to crops, exposure may 

occur with the uptake of ethalfluralin residues in the soil as well as any residual residues that are 

remain in the plant system from the seed after germination. However, it should be noted that the 

extent to which ethalfluralin is systemic is unknown. While a rough indicator, ethalfluralin’s log 

Kow of 5.11 suggests some ability for ethalfluralin to remain within the plant material for some 

period of time. Dinitroaniline herbicides are absorbed somewhat by plant root systems, and to a 

greater extent by young seedling shoot organs such as the hypocotyl or coleoptile. Little or no 

translocation of these herbicides occurs in plants (Parka and Sopa, 1977).

• Other General Uncertainties for Screening Risk Assessments

Routes of Exposure

The screening assessment does not consider ethalfluralin dermal exposure to terrestrial 

organisms. The Agency is actively pursuing modeling techniques to account for dermal exposure 

via direct application of spray and by incidental contact with contaminated vegetation, soil and 

water. Additionally, exposure from inhalation is not assessed. While the compound is 

moderately volatile, its atmospheric half-life is limited given its propensity to react with 

hydroxyl radicals and undergo photolysis.

Age Class and Sensitivity of Effects Thresholds 

It is generally recognized that test organism age may have a significant impact on the observed 

sensitivity to a toxicant. Acute toxicity data for fish are collected on juvenile fish, and aquatic 

invertebrate acute toxicity testing is performed on recommended immature age classes. 

Similarly, acute dietary testing with birds is also performed on juveniles. 

Testing of juveniles may overestimate the toxicity of direct acting pesticides in adults. As 

juvenile organisms may not have fully developed metabolic systems and may not possess the 

ability to transform and detoxify xenobiotics equivalent to the older/adult organism. The 

screening-level risk assessment has no current provisions for a generally applied method that 

accounts for this uncertainty. In so far as the available toxicity data may provide ranges of 

sensitivity information with respect to age class, the risk assessment uses the most sensitive lifestage information as the conservative screening endpoint.

Lack of Effects Data for Amphibians and Reptiles 

Currently, toxicity studies on amphibians and reptiles are not required for pesticide registration. 

Since these data are lacking, the Agency uses fish as surrogates for aquatic-phase amphibians 

and birds as surrogates for terrestrial-phase amphibians and reptiles. If other species are more or 

less sensitive to ethalfluralin than the surrogates, risks may be under- or overestimated, 

respectively. The Agency is not limited to a base set of surrogate toxicity information in 
75

establishing risk assessment conclusions. The Agency also considers toxicity data on nonstandard test species when available. Further research is needed to determine whether, in 

general, reptiles and terrestrial-phase amphibians are suitably represented by bird species in 

assessing risks for ethalfluralin and fish are an appropriate surrogate for aquatic-phase 

amphibians. 

Use of the Most Sensitive Species Tested 

Although the screening-level risk assessment relies on a selected toxicity endpoint from the most 

sensitive species tested, it does not necessarily mean that the selected toxicity endpoints reflect 

sensitivity of the most sensitive species existing in a given environment. The relative position of 

the most sensitive species tested in the distribution of all possible species is a function of the 

overall variability among species to a particular chemical. The relationship between the 

sensitivity of the most sensitive tested species versus wild species (including listed species) is 

unknown and a source of significant uncertainty. In addition, in the case of listed species, there is 

uncertainty regarding the relationship of the listed species' sensitivity and the most sensitive 

species tested. 

Sublethal Effects

When assessing acute risk, the screening-level risk assessment relies on the acute mortality 

endpoint as well as a suite of sublethal responses to the pesticide. Consideration of additional 

sublethal data in the effects determination is exercised on a case-by-case basis and only after 

careful consideration of the nature of the sublethal effect measured and the extent and quality of 

available data to support establishing a plausible relationship between the measure of effect 

(sublethal endpoint) and the assessment endpoints. However, the full suite of sublethal effects 

from valid open literature studies is considered for the characterization purposes within the 

context of the extent to which the effects can be linked to assessment endpoints of impaired 

growth, survival or reproduction. 

To the extent to which sublethal effects are not considered in this assessment, the potential direct 

and indirect effects of ethalfluralin on listed species may be underestimated.

Terrestrial Plants

The EC25 and NOAEC values from terrestrial plant studies only assess the effects on initial plant 

growth and survival. EPA current tests do not provide information on effects to reproduction, 

fruit formation or fruit yield. However, it is currently assumed that a 25 percent or greater effect 

on initial plant growth is indicative of subsequent reductions on plant populations, fruit 

formation and yield. In addition, the number of laboratory test species only account for eight of 

the 300 known plant families. The range of sensitivity of various plants to a phytotoxicant can 

be significantly higher than that exhibited in the laboratory because of intraspecies and 

interspecies variability, genetic differences in adaptability to environmental stresses, and 

magnitude and duration of exposure. 
76

9 Endocrine Disruptor Screening Program

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

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

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

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

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

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

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

studies that assess growth, developmental and reproductive effects in different taxonomic groups. 

As part of registration review for ethalfluralin, EPA reviewed these data and selected the most 

sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. 

However, as required by FFDCA section 408(p), ethalfluralin is subject to the endocrine screening 

part of the Endocrine Disruptor Screening Program (EDSP). 

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

and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a 

“naturally occurring estrogen, or other such endocrine effects as the Administrator may designate.” 

The EDSP employs a two-tiered approach to making the statutorily required determinations. Tier 

1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to 

interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go 

through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal

systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of 

the Tier 2 tests are necessary based on the available data. Tier 2 testing is designed to identify any 

adverse endocrine-related effects caused by the substance, and establish a dose-response 

relationship between the dose and the E, A, or T effect.

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

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

which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals 

identified for EDSP screening was published on June 14, 201312 and includes some pesticides 

scheduled for registration review and chemicals found in water. Neither of these lists should be 

construed as a list of known or likely endocrine disruptors. Ethalfluralin is not on List 1. For further 

information on the status of the EDSP, the policies and procedures, the lists of chemicals, future 

lists, the test guidelines and the Tier 1 screening battery, please visit our website.13

10 Federally Threatened and Endangered (Listed) Species of 

Concern

Before completing this Registration Review, the Agency will conduct an ecological risk 

assessment to address the Agency’s obligations under both the Endangered Species Act (ESA) 

and FIFRA. While the risk assessment supporting this proposed interim Registration Review 

 12 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals. 13 http://www.epa.gov/endo/
77

decision evaluates risks to species that are not subject to the ESA, EPA is still in the process of 

conducting a risk assessment for endangered and threatened (listed) species and their designated 

critical habitats for ethalfluralin. In this proposed interim decision, therefore, EPA has not 

completed effects determinations for listed species associated with the registered uses of 

ethalfluralin. 

At this time, EPA has not fully developed its risk assessment process for listed species. In 

November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the National 

Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department of 

Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks to 

listed species from pesticides. The Interim Approaches were developed jointly by the Agencies 

in response to the National Academy of Sciences’ (NAS) recommendations and reflect a 

common approach to risk assessment shared by the Agencies as a way of addressing scientific 

differences between the EPA and the Services. The NAS report, available 

at http://www.nap.edu/catalog.php?record_id=18344, outlines recommendations on specific 

scientific and technical issues related to the development of pesticide risk assessments that EPA 

and the Services must conduct in connection with their obligations under the ESA and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on November 

15, 2013. In addition, the EPA presented the joint Interim Approaches at the December 2013 

Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues Research and 

Evaluation Group (SFIREG) meetings, allowing additional opportunities for stakeholders to 

comment on the Interim Approaches. As part of a phased, iterative process for developing the 

Interim Approaches, the Agencies will also consider public comments on the Interim 

Approaches in connection with the development of upcoming Registration Review 

decisions. The details of the joint Interim Approaches are contained in the white paper “Interim 

Approaches for National-Level Pesticide Endangered Species Act Assessments Based on the 

Recommendations of the National Academy of Sciences April 2013 Report,” dated November 1, 

2013, available at http://www.epa.gov/espp/2013/nas.html. 

11Conclusions

Ethalfluralin is characterized as having low to moderate persistence; although the compound is 

subject to relatively rapid photolysis, the conditions (clear, shallow water) favoring this route of 

abiotic degradation may be limited. The compound is mostly immobile in soil; however, it can 

move to adjacent waters via spray drift and runoff of sediment-bound residues (erosion). While 

the compound is moderately volatile, its atmospheric half-life is limited given its propensity to 

react with hydroxyl radicals and undergo photolysis. Given the limited solubility of ethalfluralin

and its propensity to sorb to organic matter, the compound is expected to be associated with 

benthic sediments in aquatic systems rather than dispersed in the water column. 

When estimates of ethalfluralin exposure in terrestrial and aquatic environments are compared to 

the available ecotoxicity data, the results of the screening-level assessment indicate a potential 

risks of concern for both aquatic and terrestrial taxa for current uses of ethalfluralin. RQ values 

exceed the acute and chronic risk LOCs for freshwater and estuarine fish (Table 38); since fish 

serve as surrogates for aquatic-phase amphibians, these risk concerns extend to this taxon as 
78

well. Acute RQ values also exceed the acute risk LOC for estuarine/marine invertebrates and in 

the absence of data to the contrary, chronic risk is presumed for estuarine/marine sedimentdwelling invertebrates (Table 38). Risk concerns are also identified for aquatic plants. In the 

terrestrial environment, risk concerns are identified for mammals from chronic exposure as well 

as to terrestrial plants (Table 39). 

Ethalfluralin is very highly toxic to aquatic animals. In general, risk quotients for aquatic 

organisms are calculated considering parent compound alone. Acute risk concerns exist for 

endangered freshwater fish and invertebrates (RQs 0.06 – 0.39) and endangered estuarine / 

marine fish and invertebrates at the highest application rates (RQs 0.05-0.07). Chronic risk 

concerns exist for freshwater fish from multiple application rates (RQs 1.0 to 3.4) and to 

estuarine/marine fish at the highest application rate (RQ = 1.13) but not to aquatic invertebrates. 

Sediment-dwelling freshwater invertebrates were also determined to be at risk from chronic 

exposure to sediment (RQs 1.3-4.0). Risk is identified to non-listed aquatic vascular plants only 

at the highest application rates (RQ = 1.7). Risk to listed vascular plants is identified for 

application rates ranging from 1 to 1.7 lbs ai/A with RQs from 3 to 10.4. Risk to listed nonvascular plants is only identified at the highest application rate of 1.7 lbs ai/A (RQ = 1.1). 

Buffers to mitigate risk to listed aquatic plants and animals range from 0 to 65 feet. Ensuring 

large droplet sizes and low boom heights could substantially reduce impact of spray drift to the 

aquatic environment though runoff would still contribute to exposure.

For terrestrial wildlife, ethalfluralin is practically non-toxic to birds, mammals, and terrestrial 

insects on an acute exposure basis. Since the time of the problem formulation, the Agency now 

also requires acute and chronic toxicity studies for larval bees and chronic toxicity studies for 

adult bees. While ethalfluralin is classified as practically non-toxic to honey bees on an acute 

contact exposure basis, the potential impacts of ethalfluralin on adult and larval bees from

chronic exposure is uncertain. 

No risk is identified for either non-listed or listed birds from acute or chronic exposure to 

ethalfluralin. While dietary-based RQs are below the chronic risk LOC, dose-based RQ values 

exceed the chronic risk LOC for mammals for foliar applications of emulsifiable concentrates 

(RQs ranged from 0.01 to 3.3). RQs for small- and medium-sized mammals (15 g and 35 g 

mammals respectively) exceed the chronic LOC of 1.0 for short grass, tall grass, broadleaf plants 

for uses on alfalfa, cucurbits, potatoes and sunflower with application rates that ranged from 1 to 

1.9 lbs a.i./A. There is also potential risk to piscivorous mammals from chronic exposure with 

one LOC exceedance for the large river otter at the highest application rate (RQ 1.1). 

Consistent with the herbicidal uses of ethalfluralin, risks of concern are identified for terrestrial 

plants for all of the uses/rates evaluated. Terrestrial plant risk was identified for every use of 

ethalfluralin (non-listed and listed RQs ranging between <0.1 – 131); both runoff and spray drift 

processes contribute to the overall risk. Buffers required to mitigate the spray drift to terrestrial 

plants range from 7 feet to 157 feet depending on application method and application rate. 

The overall risk conclusions for aquatic and terrestrial taxa broken down by each use of

ethalfluralin are presented below in Table 38 and Table 39, respectively. 
79

Table 38. Summary of adverse impacts for aquatic organisms expected from the existing 

uses of ethalfluralin.

Adverse Impacts Expected for Aquatic Organisms? (No/Yes: A = Acute, C=Chronic)

Proposed 

Use 

(App. 

Rate - lbs. 

a.i./A)

Freshwat

er Fish

Estuarine/Ma

rine Fish

Freshwater 

Invertebrates(W

ater Column)

Estuarine/

Marine 

Invertebra

tes (Water 

Column)

Freshwater 

and 

Estuarine/Ma

rine Benthic 

Invertebrates 

(Sediment)

Freshwater 

and 

Estuarine/Ma

rine Benthic 

Invertebrates 

(Pore water)

Aquat

ic 

Plants

Alfalfa, 

Beans 

with low 

broadcast 

spray EC1 

(1.698)

YesAC YesAC No YesA Yes No Yes

Alfalfa, 

Beans 

with 

chemigatio

n EC3 

(1.698)

YesAC YesAC No YesA Yes No Yes

Beans 

granular 

(1.69)

YesAC No No YesA Yes No Yes

Clover 3" 

incorporat

ed (1.5)

No ? No No Yes No Yes

Cucurbits 

with low 

broadcast 

spray (1.7)

YesAC YesAC No YesA Yes No Yes

Dill 

ground 

spray 

(1.13)

YesAC No No No Yes No Yes

Lentils, 

Mustard 

granular 

formulatio

n 2" 

incorporati

on (0.95)

YesAC No No YesA Yes No Yes

OilseedSunflower, 

Jojoba, etc 

(1.7) 

Granular 2 

inch 

incorporati

on

YesAC No No No Yes No Yes
80

Adverse Impacts Expected for Aquatic Organisms? (No/Yes: A = Acute, C=Chronic)

Proposed 

Use 

(App. 

Rate - lbs. 

a.i./A)

Freshwat

er Fish

Estuarine/Ma

rine Fish

Freshwater 

Invertebrates(W

ater Column)

Estuarine/

Marine 

Invertebra

tes (Water 

Column)

Freshwater 

and 

Estuarine/Ma

rine Benthic 

Invertebrates 

(Sediment)

Freshwater 

and 

Estuarine/Ma

rine Benthic 

Invertebrates 

(Pore water)

Aquat

ic 

Plants

OilseedSunflower, 

Jojoba, etc 

(1.7) 

Granular F 

3 inch 

incorporati

on

No No No No Yes No Yes

OilseedSunflower, 

Jojoba, etc 

(1.7) EC3 

chemigatio

n

YesAC YesC No YesA Yes No Yes

Oilseed –

Crambe, 

Rapeseed 

(canola), 

etc. group 

(0.95) 

EC2 spray 

with 2 

inch 

incorporati

on

YesAC No No No Yes No

Oilseed –

Crambe, 

Rapeseed 

(canola), 

etc. group 

(0.95) G 

with 2 

inch 

incorporati

on

No No No No Yes No Yes

OilseedSafflower 

(1.15) 

granular 

with 2 

inch 

incorporati

on

No No No No Yes No Yes

Peanuts 

granular 

formulatio

n (1.15) 

with 2 

inch 

incorporati

on

YesAC No No No Yes No Yes
81

Adverse Impacts Expected for Aquatic Organisms? (No/Yes: A = Acute, C=Chronic)

Proposed 

Use 

(App. 

Rate - lbs. 

a.i./A)

Freshwat

er Fish

Estuarine/Ma

rine Fish

Freshwater 

Invertebrates(W

ater Column)

Estuarine/

Marine 

Invertebra

tes (Water 

Column)

Freshwater 

and 

Estuarine/Ma

rine Benthic 

Invertebrates 

(Sediment)

Freshwater 

and 

Estuarine/Ma

rine Benthic 

Invertebrates 

(Pore water)

Aquat

ic 

Plants

Peanuts 

EC with 2 

inch 

incorporat

ed (1.15)

YesAC No No No Yes No Yes

Peas EC 

(0.75) 2 

inch 

incorporati

on

? No No No Yes No Yes

Peas 

granular 

formulatio

n (0.75) 2 

inch 

incorporati

on

? No No No Yes No Yes

Potatoes 

chemigatio

n (1.028)

YesAC No No No Yes No Yes

Potatoes 

ground 

(1.028)

YesAC No No No Yes No Yes

Soybeans 

Granular 

(1.3) 2 

inch 

incorporati

on

YesAC No No No Yes No Yes

Table 39. Summary of adverse impacts for terrestrial organisms expected from the existing 

uses of ethalfluralin.

Proposed 

Use

Adverse Impacts Expected for Terrestrial Organisms? (No/Yes: A = Acute, 

C=Chronic)

(App. Rate 

-

lbs. a.i./A) Birds Mammals Piscivorous 

Birds

Piscivorous 

Mammals

Terrestrial 

Plants

Terrestrial 

Invertebrates

Alfalfa, 

Beans with 

low 

broadcast 

spray EC1 

(1.698)

No YesC No YesC Yes No
82

Proposed 

Use

Adverse Impacts Expected for Terrestrial Organisms? (No/Yes: A = Acute, 

C=Chronic)

(App. Rate 

-

lbs. a.i./A) Birds Mammals Piscivorous 

Birds

Piscivorous 

Mammals

Terrestrial 

Plants

Terrestrial 

Invertebrates

Alfalfa, 

Beans with 

chemigation 

EC3 (1.698)

No YesC No YesC Yes No

Beans 

granular 

(1.69)

No No No No Yes No

Clover 3" 

incorporated 

(1.5)

No No No No Yes No

Cucurbits 

with low 

broadcast 

spray (1.7)

No YesC No No Yes No

Dill ground 

spray (1.13) No YesC No No Yes No

Lentils, 

Mustard 

granular 

formulation 

2" 

incorporation 

(0.95)

No YesC No No Yes No

OilseedSunflower, 

Jojoba, etc 

(1.7) 

Granular 2 

inch 

incorporation

No No No No Yes No

OilseedSunflower, 

Jojoba, etc 

(1.7)

Granular F 3 

inch 

incorporation

No No No No Yes No

OilseedSunflower, 

Jojoba, etc 

(1.7) EC3 

chemigation

No YesC No No Yes No
83

Proposed 

Use

Adverse Impacts Expected for Terrestrial Organisms? (No/Yes: A = Acute, 

C=Chronic)

(App. Rate 

-

lbs. a.i./A) Birds Mammals Piscivorous 

Birds

Piscivorous 

Mammals

Terrestrial 

Plants

Terrestrial 

Invertebrates

Oilseed –

Crambe, 

Rapeseed 

(canola), etc. 

group (0.95) 

EC2 spray 

with 2 inch 

incorporation

No YesC No No Yes No

Oilseed –

Crambe, 

Rapeseed 

(canola), etc. 

group (0.95) 

G with 2 

inch 

incorporation

No No No No Yes No

OilseedSafflower 

(1.15) 

granular with 

2 inch 

incorporation

No No No No Yes No

Peanuts 

granular 

formulation 

(1.15) with 2 

inch 

incorporation

No No No No Yes No

Peanuts EC 

with 2 inch 

incorporated 

(1.15)

No No No No Yes No

Peas EC 

(0.75) 2 inch 

incorporation

No No No No Yes No

Peas 

granular 

formulation 

(0.75) 2 inch 

incorporation

No No No No Yes No

Potatoes 

chemigation 

(1.028)

No YesC No No Yes No
84

Proposed 

Use

Adverse Impacts Expected for Terrestrial Organisms? (No/Yes: A = Acute, 

C=Chronic)

(App. Rate 

-

lbs. a.i./A) Birds Mammals Piscivorous 

Birds

Piscivorous 

Mammals

Terrestrial 

Plants

Terrestrial 

Invertebrates

Potatoes 

ground 

(1.028)

No No No No Yes No

Soybeans 

Granular 

(1.3) 2 inch 

incorporation

No No No No Yes No
85

12 References 

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87

Appendix A. Environmental Fate and Ecological Effects 

Data for Ethalfluralin

113101 Ethalfluralin Fate Chemistry Bibliography Final 11/18/13

161-1 Hydrolysis

MRID Citation Reference

94805 Mosier, J.W.; Sullivan, W.L.; Saunders, D.G. (1976) A Hydrolysis 

Study on the Herbicide Ethalfluralin. (Unpublished study received Feb 

4, 1982 under 1471-122; submitted by Elanco Products Co., Div. of Eli 

Lilly and Co., Indianapolis, Ind.; CDL: 070676-D) 

92062029 Environ Corp. (1990) Dowelanco Phase 3 Summary of MRID 

00094805. A Hydrolysis Study on the Herbicide Ethalfluralin. Prepared 

by LILLY RESEARCH LABS. 10 p. 

161-2 Photodegradation-water

MRID Citation Reference

41086401 Carpenter, M.; Fennessey, M. (1988) Determination of the Photolysis 

of Carbon 14-Ethalfluralin in Aqueous Solution: ABC Second Amended 

Final Report #36868. Unpublished study prepared by Analytical BioChemistry Laboratories, Inc. 76 p. 

41613916 Carpenter, M.; Fennessey, M. (1988) Determination of the Photolysis 

Rate of ?carbon 14|-Ethalfluralin in Aqueous Solution: Final Re- port 

(Second Amended). Lab Project Number: 36868. Unpublished study 

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94807 Day, E.W., Jr. (1976) Preliminary Photochemical Studies with the 

Herbicide Ethalfluralin. (Unpublished study received Feb 4, 1982 under 

1471-122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL:070676-F) 

94808 Mosier, J.W.; Saunders, D.G. (1980) Photolysis of Ethalfluralin in 

Aqueous Solution. (Unpublished study received Feb 4, 1982 under 

1471-122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL:070676-G) 

94810 Saunders, D.G.; Sieck, R.F.; Shuey, E.W. (1982) Vapor Phase Photolysis of Ethalfluralin. (Unpublished study received Feb 4, 1982 under 

1471-122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL:070676-I) 
88

161-3 Photodegradation-soil

MRID Citation Reference

94809 Gray, J.E.; Saunders, D.G.; Sieck, R.F.; et al. (1979) Rate of 

Photolysis of Ethalfluralin on Soil and Glass Plates. (Unpublished study 

received Feb 4, 1982 under 1471-122; submitted by Elanco Products 

Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070676-H) 

41613917 Dykes, J. (1990) Determination of the Photolysis Rate of carbon 14-

Ethalfluralin on the Surface of Soil: Final Report. Lab Project Number 

38051. Unpublished study prepared by ABC Labs, Inc. 41 p. 

162-1 Aerobic soil metabolism

MRID Citation Reference

41613918 Graper, L. (1990) Aerobic Metabolism of carbon 14-Ethalfluralin in Sandy 

Loam Soil: Lab Project Number: ABC 0402. Unpublished study prepared by 

DowElanco. 37 p. 

835.4100 Aerobic soil metabolism

MRID Citation Reference

48509301 Breaux, N.; Douglas, M.; Chavez-Green, A.; et al. (2011) Dow AgroSciences 

Response to US EPAs Ethalfluralin Registration Review Docket EPA-OPP2011-0094. Project Number: NTB053111/OCR. Unpublished study prepared 

by Dow AgroSciences, LLC. 29 p.

48915601 Diehl, M. (2003) Degradation of (Carbon 14)-Ethalfluralin in Three Soils 

Incubated Under Aerobic Conditions. Project Number: 842133. Unpublished 

study prepared by RCC Umweltchemie Ag. 92p.

162-2 Anaerobic soil metabolism

MRID Citation Reference
89

41613919 Graper, L. (1990) Anaerobic Metabolism of carbon 14-Ethalfluralin in 

Sandy Loam Soil: Lab Project Number: ABC 0403. Unpublished study 

prepared by DowElanco. 41 p. 

94812 Golab, T.; Sassic, K.A.; Wooten, H.L. (1981)14C Ethalfluralin Anaerobic Soil Degradation Study: Experiment No. ABC-0111. (Unpublished study received Feb 4, 1982 under 1471-122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070676-K)

162-3 Anaerobic aquatic metab.

MRID Citation Reference

42930102 Lawrence, B.; Mobley, S.; Kesterson, A. (1993) Anaerobic Aquatic 

Metabolism of (carbon 14)Ethalfluralin: Lab Project Number: 650: 

1516: MET91025. Unpublished study prepared by PTRL East, Inc. 172 

p. 

163-1 Leach/adsorp/desorption

MRID Citation Reference

94814 Saunders, D.G.; Smith, S.K.; Sieck, R.F.; et al. (1982) Soil Ad- sorption 

and Desorption of Ethalfluralin: I-EWD-81-04. (Unpublished study 

received Feb 4, 1982 under 1471-122; submitted by Elanco Products 

Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070676-O) 

94815 Sullivan, W.; Saunders, D.G. (1976) Aged Leaching Study with the 

Herbicide Ethalfluralin. (Unpublished study received Feb 4, 1982 under 

1471-122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL:070676-P) 

94816 Gray, J.E.; Loh, A.; Sieck, R.F.; et al. (1982) Laboratory Leaching of 

Ethalfluralin. (Unpublished study received Feb 4, 1982 under 1471-

122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL:070676-Q) 

94820 Golab, T.; Sassic, K.A.; Wooten, H.L. (1981) Dissipation of 14C 

Ethalfluralin from Water-hydrosoil Systems Exposed to Natural 

Environmental Conditions: Experiment No. ABC-0082. (Unpublished 

study received Feb 4, 1982 under 1471-122; submitted by Elanco 

Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070676-

U) 

135185 Loh, A.; Sullivan, W. (1978) Adsorption Coefficient of Ethalfluralin in 

Soil. (Unpublished study received Aug 24, 1978 under 1471-EX-63; 
90

submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, IN; CDL:097325-K) 

41890102 Saunders, D. (1991) Ethalfluralin Aged Soil Leaching Study: Lab 

Project No. AAC9047. Unpublished study prepared by Dow-Elanco. 58 

p. 

42437201 Saunders, D. ; Powers, F. (1987) Adsorption and Desorption of 

Ethalfluralin on Soil: Lab Project Number: EWD8723. Unpublished 

study prepared by Lilly Research Laboratories. 74 p. 

42437202 Saunders, D.G. and F.L. Powers (1987) Adsorption and Desorption of 

Ethalfluralin on Soil: Submitted and Performed by DowElanco, 

Greenfield, Indiana. MRID 42437202

163-2 Volatility - lab

MRID Citation Reference

42496601 Kesterson, A. (1992) Laboratory Volatility of ?Carbon 14|Ethalfluralin: 

Lab Project Number: 579: 1488. Unpublished study prepared by PTRL 

East Inc. 74 p. 

164-1 Terrestrial field dissipation

MRID Citation Reference

28626 Golab, T.; Sherman, W.E.; Wooten, H.L.; et al. (1980) Radiochemical Studies 

with 14C Ethalfluralin in Soil and Various Primary and Rotational Crop Plants. 

(Unpublished study received Feb 22, 1980 under 1471-EX-63; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:099264-

A) 

94818 Golab, T.; Sherman, W.E.; Wooten, H.L.; et al. (1980) Radiochemical Studies 

with 14C Ethalfluralin in Soil and Various Primary and Rotational Crop Plants. 

(Unpublished study received Feb 4, 1982 under 1471-122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070676-

S) 

94819 Decker, O.D.; Sieck, R.F.; Shuey, E.W. (1982) Ethalfluralin Three- year Soil 

Dissipation Studies. (Unpublished study received Feb 4, 1982 under 1471-122; 

submitted by Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070676-T) 

41441401 Decker, O. (1990) Field Dissipation of Ethalfluralin Following Application of 

Sonalan to Bare Soil and Seeded with Dry Beans: Lab Project Number: 

AAC8811. Unpublished study prepared by Dow Elanco. 188 p. 
91

41613920 Decker, O. (1990) Field Dissipation of Ethalfluralin Following Application of 

SONOLAN to Bare Soil: Lab Project Number: AAC8811. Unpublished study 

prepared by DowElanco. 188 p. 

41978101 Decker, O.D. (1991) Ethalfluralin Dissipation Study. Laboratory ID No. 

AAC8712. Unpublished Study Performed and Submitted by DowElanco, 

Indianapolis, IN.

164-2 Aquatic field dissipation

MRID Citation Reference

94806 Hamelink, J.L.; Loh, A. (1976) Dissipation of Ethalfluralin from Water. 

(Unpublished study received Feb 4, 1982 under 1471-122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070676-

E) 

Golab, T. 1981 Dissipation from Water Hydrosoil Systems

165-1 Confined rotational crop

MRID Citation Reference

42930103 O'Neal, S.; Johnson, T. (1993) A Confined Rotational Crop Study with 

(Carbon 14)-Ethalfluralin: Lab Project Number: 576: 1509. Unpublished 

study prepared by PTRL East, Inc. 312 p. 

165-4 Bioaccumulation in fish

MRID Citation Reference

41994902 Woodburn, K.; Hansen, S.; Ball, T.; et al. (1991) Ethalfluralin: 

Bioconcentration in Rainbow Trout (Oncorhynchus mykiss): Lab Project 

Number: ES-DR-0233-3655-1. Unpublished study prepared by Dow 

Chemical Co., Environmental Tox. & Chem. Research Lab. 44 p. 

Non Guideline Selections

94765 Peloso, T.S.; Kline, R.M.; Sieck, R.F.; et al. (1982) The Effect of Ethalfluralin 

on the Degradation of Cellulose, Starch, and Protein in Soil: I-RMK-81-02. 

(Unpublished study received Feb 4, 1982 under 1471-122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070677-T) 
92

94766 Kline, R.M.; Knox, J.W.; Sieck, R.F.; et al. (1982) The Effect of Ethalfluralin 

on Soil Microorganisms. (Unpublished study received Feb 4, 1982 under 

1471-122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL: 070677-K) 

94767 Kline, R.M.; Knox, T.W.; Zornes, L.L.; et al. (1982) The Effect of Ethalfluralin 

on Sewage Microorganisms: I-BSD-79-12 & I-BSD-80- 01. (Unpublished 

study received Feb 4, 1982 under 1471-122; submitted by Elanco Products 

Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070677-L) 

94813 Kline, R.M.; Peloso, J.S.; Sieck, R.F.; et al. (1982) Microbial Interactions--

The Effect of Ethalfluralin on Nitrogen Fixation by Anabaena flos aquae. 

(Unpublished study received Feb 4, 1982 under 1471-122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070676-M)

94821 Saunders, D.G.; Sieck, R.F.; Shuey, E.W. (1982) Estimated Water 

Concentration of Ethalfluralin Following Runoff from a Sonalan-treated 

Watershed. (Unpublished study received Feb 4, 1982 under 1471-122; 

submitted by Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070676-V) 

112920 Saunders, D.; Sieck, R.; Shuey, E. (1982) Estimated Water Concentration of 

Ethalfluralin following Runoff from a Sonalan-treated Watershed. 

(Unpublished study received Sep 2, 1982 under 1471- 122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, IN; CDL:248250-

A) 

43659501 MacCoy, D.; Crepeau, K.; Kuivila, K. (1995) Dissolved Pesticide Data for the 

San Joaquin River at Vernalis and the Sacramento River at Sacramento, 

California, 1991-94: Open File Report 95-110. Prepared by U.S. Geological 

Survey in cooperation with the U.S. EPA and the California Regional Water 

Quality Control Board; available from U.S. Government Printing Office. 31 p. 

43659502 Crepeau, K.; Domagaiski, J.; Kuivila, K. (1994) Methods of Analysis and 

Quality-Assurance Practices of the U.S. Geological Survey Organic 

Laboratory, Sacramento, California--Determination of Pesticides in Water by 

Solid-Phase Extraction and Capillary-Column Gas Chromatography/Mass 

Spectrometry: Open File Report 94-362. Prepared by the U.S. Geological 

Survey; available from U.S. Government Printing Office. 21 p. 

94817 Pikal, M.J. (1976) Vapor Pressure of Ethalfluralin. (Unpublished study 

received Feb 4, 1982 under 1471-122; submitted by Elanco Products Co., 

Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070676-R)

Product Chemistry- check with RD

63-9 Vapor Pressure

MRID Citation Reference

42437202 Decker, O. (1987) Vapor Pressure of Ethalfluralin: Lab Project Number: ODD8721. 

Unpublished study prepared by Lilly Research Laboratories. 11 p. 
93

63-11 Oct/Water partition Coef.

MRID Citation Reference

41890101 Day, E. (1991) Octanol/Water Partition Coefficient of Ethalfluralin : Lab Project 

Number: EWD9104. Unpublished study prepared by Lilly Analytical Chemistry Dept. 9 

p. 

63-13 Stability

MRID Citation Reference

41613901 Hudson, J.; Smith, C. (1990) Ethalfluralin Technical: Chemical Stability: Lab Project 

Number: TIL909004. Unpublished study pre- pared by DowElanco. 6 p. 

42929601 Stolz, W. (1993) Determination of the Stability of Ethalfluralin Technical to Selected 

Metals and Metal Ions at Elevated Temperatures: Lab Project Number: FOR93036. 

Unpublished study prepared by 

Appendix B. Ethafluralin ECO Effects Bibliography 

Revised August 2015

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

94760 West, H.C.; Kehr, C.C.; Hamelink, T.L.; et al. (1980) The Toxicity of 

Compound 94961 (Ethalfluralin) to Bobwhite Quail in a 14-day Acute Oral 

Study: Study No. 7012-78. (Unpublished study received Feb 4, 1982 under 

1471-122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL: 070677-E) 

135181 Elanco Products Co. (1973) Acute Oral Toxicity--Mallard Duck: Study WF-O3-73. (Unpublished study received Aug 24, 1978 under 1471-EX-63; 

CDL:097325-D) 

135182 Elanco Products Co. (1973) Acute Oral Toxicity--Bobwhites: Study Q-O-6-73. 

(Unpublished study received Aug 24, 1978 under 1471- EX-63; CDL:097325-

E) 

48915502 Hubbard, P.; Beavers, J. (2012) Ethalfluralin TGAI: An Acute Oral Toxicity 

Study with the Zebra Finch. Project Number: 379/295, 120326. Unpublished 

study prepared by Wildlife International, Ltd. 35p.
94

92062002 Environ Corp. (1990) Dowelanco Phase 3 Summary of MRID 00094760. The 

Toxicity of Compound 94961 (Ethalfluralin) to Bobwhite Quail in a 14-Day 

Acute Oral Study: Study No. 7012-78. Prepared by LILLY RESEARCH 

LABS. 11 p. 

850.2100 Avian acute oral toxicity test

MRID Citation Reference

48509301 Breaux, N.; Douglas, M.; Chavez-Green, A.; et al. (2011) Dow 

AgroSciences Response to US EPAs Ethalfluralin Registration Review 

Docket EPA-OPP-2011-0094. Project Number: NTB053111/OCR. 

Unpublished study prepared by Dow AgroSciences, LLC. 29 p.

48915501 Burri, R. (2002) GF-705 Ethalfluralin 333 g/L: Acute Oral Toxicity Test in 

the Japanese Quail. Project Number: 841916. Unpublished study 

prepared by RCC Umweltchemie Ag. 56p.

48915502 Hubbard, P.; Beavers, J. (2012) Ethalfluralin TGAI: An Acute Oral 

Toxicity Study with the Zebra Finch. Project Number: 379/295, 120326. 

Unpublished study prepared by Wildlife International, Ltd. 35p.

71-2 Avian Dietary Toxicity

MRID Citation Reference

94761 Kehr, C.C.; Hamelink, T.L.; Brannon, D.R.; et al. (1980) The Toxicity of 

Compound 94961 (Ethalfluralin) to Bobwhite Quail in a 5-day Dietary Study: 

Study No. 7028-78. Includes method AVD dated Nov 7, 1978. (Unpublished 

study received Feb 4, 1982 under 1471-122; submitted by Elanco Products 

Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL:070677-F) 

94762 Karnak, R.E.; Kehr, C.C.; Hamelink, T.L.; et al. (1980) The Toxicity of 

Compound 94961 (Ethalfluralin) to Mallard Ducks in a 5-day Dietary Study: 

Study No. 7030-78. (Unpublished study received Feb 4, 1982 under 1471-

122; submitted by Elanco Products Co., Div. of Eli Lilly and Co., 

Indianapolis, Ind.; CDL:070677-G) 

92062003 Environ Corp. (1990) Dowelanco Phase 3 Summary of MRID 00094761. 

The Toxicity of Compound 94961 (Ethalfluralin) to Bobwhite Quail in a 5-

Day Dietary Study: Project No. 7028-78. Prepared by LILLY RESEARCH 

LABS. 14 p. 

92062004 Environ Corp. (1990) Dowelanco Phase 3 Summary of MRID 00094762. 

The Toxicity of Compound 94961 (Ethalfluralin) to Mallard Ducks in a 5-Day 

Dietary Study: Project No. 7030-78. Prepared by LILLY RESEARCH LABS. 

14 p. 

 71-4 Avian Reproduction
95

MRID Citation Reference

94763 Ringer, R.K.; Breslin, W.; Floga, C.; et al. (1981) The Toxicity of Ethalfluralin 

(El-161, Compound 94961) in a One-generation Reproduction Study with 

Mallards: Study AO2179. (Unpublished study received Feb 4, 1982 under 

1471-122; prepared in cooperation with Michigan State Univ., submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL: 

070677-H) 

94764 Ringer, R.K.; Breslin, W.; Flaga, C.; et al. (1981) The Toxicity of Ethalfluralin 

(El-161, Compound 94961) in a One-generation Reproduction Study with 

Bobwhite: Study AO2079. (Unpublished study received Feb 4, 1982 under 

1471-122; prepared in cooperation with Michigan State Univ., submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; CDL: 

070677-I) 

92062005 Environ Corp. (1990) Dowelanco Phase 3 Summary of MRID 00094764. 

The Toxicity of Ethalfluralin (EL-161,Compound 94961) in One-generation 

Reproduction Study with Bobwhite Quail: Project No. A02079. Prepared by 

LILLY RESEARCH LABS. 18 p. 

92062006 Environ Corp. (1990) Dowelanco Phase 3 Summary of MRID 00094763. 

The Toxicity of Ethalfluralin (EL-161, Compound 94961) in a Onegeneration Reproduction Study with Mallards: Study No. A02179. Prepared 

by LILLY RESEARCH LAB. 18 p. 

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

135183 Sleight, B. (1973) Acute Toxicity of 94961 to Bluegill, Rainbow Trout, and 

Goldfish (Carassius auratus). (Unpublished study received Aug 24, 1978 

under 1471-EX-63; prepared by Bionomics, Inc., submitted by Elanco 

Products Co., Div. of Eli Lilly and Co., Indianapolis, IN; CDL:097325-F) 

41460101 Murray, A.; Meyerhoff, R.; Grothe, D. (1990) Interim Report for An Acute 

Toxicity Study with Ethalfluralin and Bluegill (Lepomis macrochirus): Lab 

Project Number: F01190. Unpublished study prepared by Lilly Research 

Laboratories. 34 p. 

41475001 Murray, A.; Meyerhoff, R.; Grothe, D. (1990) Summary Report for An Acute 

Toxicity Study with Ethalfluralin and Rainbow Trout (Salmo gairdneri): Lab 

Project Number: F01090. Unpublished study pre- pared by Lilly Research 

Laboratories. 34 p. 

41613902 Murray, A. ; Grothe, D. ; Adams, E. (1990) The Acute Toxicity of 

Ethalfluralin to Bluegill (Lepomis macrochirus) in a Flow- through Test 

System: Lab Project Number: F02490. Unpublished study prepared by Lilly 

Research Labs. 2 p. 

41613903 Murray, A. ; Grothe, D. ; Adams, E. (1990) The Acute Toxicity of 

Ethalfluralin to Rainbow Trout (Salmo gairdneri) in a Flow-through Test 
96

System: Lab Project Number: F02390. Unpublished study prepared by Lilly 

Research Labs. 48 p. 

42176401 Murray, A.; Grothe, D.; Adams, E. (1992) The Acute Toxicity of Sonalan (FN 

0802), a Formulation Containing Ethalfluralin (EL-161, Compound 094961), 

to Bluegill (Lepomis macrochirus) in a Static Renewal Test System: Lab 

Project Number: FO2391. Unpublished study prepared by Lilly Research 

Labs. 46 p. 

41465901 Murray, A.; Meyerhoff, R.; Grothe, D. (1990) Summary Report for An Acute 

Toxicity Study with Ethalfluralin and Rainbow Trout (Salmo gairdneri): Lab 

Project Number: F01090. Unpublished study prepared by Lilly Research 

Laboratories. 34 p. 

94769 Hamelink, J.L.; Kehr, C.C.; Adams, E.R.; et al. (1978) The Toxicity of 

Compound 94961 (El-161) to Bluegills in a 96 Hour Soil-water Static Test:

Study No. 2111-78. Includes procedure no. 5801633 dated Sep 24, 1976. 

(Unpublished study received Feb 4, 1982 under 1471-122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070677-N) 

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

94770 Karnak, R.E.; Kehr, C.C.; Hamelink, T.L.; et al. (1980) The Toxic- ity of 

Compound 94961 (Ethalfluralin) to Daphnia magna in a 48- hour Static 

Study: Study No. 5044-78. Includes procedure no. 5801633 dated Sep 24, 

1976. (Unpublished study received Feb 4, 1982 under 1471-122; submitted 

by Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070677-O) 

42176402 Grothe, D.; Adams, E. (1992) The Acute Toxicity of Sonalan EC (FN 0802), 

a Formulation Containing Ethalfluralin (EL-161, Compound 094961), to 

Daphnia magna in a Static-Renewal Test System: Lab Project Number: 

CO1191. Unpublished study prepared by Lilly Research Labs. 37 p. 

92062007 Environ Corp. (1990) Dowelanco Phase 3 Summary of MRID 00094770. 

The Toxicity of Compound 94961 (Ethalfluralin) to Daphnia magna in a 48-

Hour Static Study: Study No. 5044-78. Prepared by LILLY RESEARCH 

LABS. 12 p. 

850.1735 Whole sediment: acute freshwater invertebrates

MRID Citation Reference

48915701 Bradley, M. (2011) Ethalfluralin - 10-Day Toxicity Test Exposing Midge 

(Chironomus dilutus) to a Test Substance Applied to Sediment Under 

Static-Renewal Conditions. Project Number: 12550/6559, 101243. 

Unpublished study prepared by Smithers Viscient Laboratories. 99p.
97

48915702 Bradley, M. (2011) 10-Day Toxicity Test Exposing Freshwater 

Amphipods (Hyalella azteca) to Ethalfluralin Applied to Sediment Under 

Static-Renewal Conditions. Project Number: 12550/6560, 101244. 

Unpublished study prepared by Smithers Viscient Laboratories. 98p.

72-3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference

41613904 Sousa, J. (1990) Ethalfluralin--Acute Toxicity to Sheepshead Minnow 

(Cyprinodon variegatus) under Flow-through Conditions: Lab Project 

Number: SLI 90-7-3404: 1982. 1289. 6108. 505. Unpublished study 

prepared by Springborn Labs, Inc. 56 p. 

41613905 Dionne, E. (1990) Ethalfluralin--Acute Toxicity to Eastern Oysters under 

Flow-through Conditions: Lab Project Number: SLI 90-07-338 1: 1982. 

1289. 6107. 504. Unpublished study prepared by Spring- born Labs, Inc. 54 

p. 

41613906 Sousa, J. (1990) Ethalfluralin--Acute Toxicity to Mysid Shrimp (Mysidopsis 

bahia) under Flow-through Conditions: Lab Project Number: SLI 90-7-3405: 

1982. 1289. 6106. 515. Unpublished study prepared by Springborn Labs, 

Inc. 56 p. 

42889801 Ward, T.; Kowalski, P.; Boeri, R. (1993) Acute Flow-Through Mollusc Shell 

Deposition Test with Ethalfluralin: Lab Project Number: 186-DO: ES-2669. 

Unpublished study prepared by T. R. Wilbury Labs, Inc. 25 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

41613907 Cocke, P.; Mohr, R.; Adams, E. (1990) The Chronic Toxicity of Ethalfluralin 

to Daphnia magna in a Flow-through Life Cycle Test: Lab Project Number: 

C00390. Unpublished study prepared by Lilly Research Labs. 69 p. 

41994901 Murray, A.; Meyerhoff, R.; Adams, E. (1991) The Toxicity of Ethalfluralin to 

Rainbow Trout (Salmo gairdneri) in a 50-Day Early Life-Stage Study: Lab 

Project Number: F02690. Unpublished study prepared by Lilly Research 

Labs. 108 p. 

42930101 Milazzo, D.; Servinski, M.; Kirk, H.; et al. (1993) Ethalfluralin: Evaluation of 

the Chronic Toxicity to the Daphnid, Daphnia magna Straus: Lab Project 

Number: 0233-3655: DECO-ES-2666. Unpublished study prepared by Dow 

Chemical Co. 49 p. 
98

42041001 Sword, M.C. and J.L. Stratton (1991) Early Life-Stage Toxicity of RH-7592 

Technical to Fathead Minnow (Pimephales promelas) under Flow-Through 

Conditions. ABC Report No. 39266. Rohm and Haas Report No. 91RC0007. Study Conducted by Analytical Bio-Chemistry Laboratories, Inc., 

Columbia Mo. Submitted by Rohm and Haas, Spring House, PA. EPA MRID 

No. 42041001.

850.1300 Daphnid chronic toxicity test

MRID Citation Reference

48509301 Breaux, N.; Douglas, M.; Chavez-Green, A.; et al. (2011) Dow AgroSciences 

Response to US EPAs Ethalfluralin Registration Review Docket EPA-OPP2011-0094. Project Number: NTB053111/OCR. Unpublished study prepared 

by Dow AgroSciences, LLC. 29 p.

49086902 Urann, K. (2013) Ethalfluralin TGAI: Full Life-Cycle Toxicity Test with Water 

Fleas, Daphnia magna, Under Flow-Through Conditions. Project Number: 

14050/6100, 120325. Unpublished study prepared by Smithers Viscient 

Laboratories. 102p.

850.1350 Mysid chronic toxicity test

MRID Citation Reference

49037801 Dinehart, S. (2012) Ethafluralin Technical: Life-Cycle Toxicity Test of the 

Saltwater Mysid, Americamysis bahia, Conducted Under Flow-Through 

Conditions. Project Number: 68166, 101246. Unpublished study prepared 

by ABC Laboratories, Inc. 90p.

850.1400 Fish early-life stage toxicity test

MRID Citation Reference

48689101 York, D. (2011) Ethalfluralin - Early Life-Stage Toxicity Test with 

Sheepshead Minnow (Cyprinodon variegatus). Project Number: 

12550/6564, 101245. Unpublished study prepared by Smithers Viscient 

Laboratories. 79p.

0.1.1 72-7 Simulated or Actual Field Testing

MRID Citation Reference

94769 Hamelink, J.L.; Kehr, C.C.; Adams, E.R.; et al. (1978) The Toxicity of 

Compound 94961 (El-161) to Bluegills in a 96 Hour Soil-water Static Test: 

Study No. 2111-78. Includes procedure no. 5801633 dated Sep 24, 1976. 

(Unpublished study received Feb 4, 1982 under 1471-122; submitted by 
99

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070677-N) 

122-1 Seed Germination/Seedling Emergence and Vegetable Vigor

MRID Citation Reference

41613911 Waldrep, T. (1989) Influence of Ethalfluralin on the Germination of Seeds of 

Ten Crop Plants: Lab Project Number: 61989013. Unpublished study prepared 

by DowElanco. 13 p. 

122-2 Aquatic plant growth

MRID Citation Reference

41613912 Murray, A.; Grothe, D.; Adams, E. (1990) Toxicity of Ethalfluralin to a 

Freshwater Green Alga (Selenastrum capricornutum) in a Static Test System: 

Lab Project Number: J01190. Unpublished study prepared by Lilly Research 

Labs. 44 p. 

123-1 Seed germination/seedling emergence and vegetative vigor

MRID Citation Reference

41613913 Waldrep, T. (1990) Influence of Ethalfluralin Pre-emergence Spray on 

Seedling Emergence and Vegetative Vigor of Ten Crop Plants: Lab 

Project Number: 61990001. Unpublished study prepared by Dow- Elanco. 

23 p. 

41613914 Waldrep, T. (1989) Influence of Ethalfluralin Post-emergence Spray on 

the Vegetative Vigor of Ten Crop Plants: Lab Project Number: 61989014. 

Unpublished study prepared by DowElanco. 19 p. 

42904201 Schwab, D. (1993) Evaluating the Effects of Ethalfluralin on the 

Vegetative Vigor of Non-Target Terrestrial Plants: Final Report: Lab 

Project Number: 40903: FAC-40903. Unpublished study prepared by ABC 

Labs, Inc. 86 p. 

No MRID

ACC 

070677

Thompson, L.L. and P.T. McKamey (1981) Crop Phytotoxicity when 

Sonalan 3EC was Applied as an Over-the-Top Post-emergence Spray to 

Seedlings of 12 Crop Species. (Unpublished Study Received Feb 4, 1982 

under 1471-122, Prepared and Submitted by Lilly Research Laboratories, 

Division of Eli Lilly and Company, Greenfield, Indiana; CDL:070677).
100

850.4225 Seedling emergence, Tier II

MRID Citation Reference

47874101 Rockliff, C. 2005 and 2008. First Amendment to Final Report: Evaluation 

of the Phytotoxicity of Sonalan (Ethalfluralin, 333 g ai/L, EC) Seedling 

Emergence and Seedling Growth Test (Based on OECD Guideline 208 A) 

– Northern Europe, 2005. Unpublished study performed by Stockbridge 

Technology Centre Ltd., North Yorkshire, UK. Laboratory Study No.: 

STC/05/E276. Study sponsored by Dow AgroSciences LLC, Indianapolis, 

Indiana. Sponsor Reference No.: EA05T1L001. Original study completed 

December 2005; Amendment to Report completed July 16, 2008.

49385904 Holou, M. (2013) Sonalan HFP (GF-1742 360 g a.s./L, EC): Effects on 

the Seedling Emergence and Growth of Non-Target Terrestrial Plants 

(Tier II). Project Number: 68750, 120537, 10/267065. Unpublished 

study prepared by ABC Laboratories, Inc. 160p.

850.4025 Target area phytotoxicity

MRID Citation Reference

47874101 Rockliff, C. (2008) Evaluation of the Phytotoxicity of Sonalan (Enthalfluralin, 

333g ai/l, EC) Seedling Emergence and Seedling Growth Test (Based on 

OECD Guideline 208 A) - Northern Europe, 2005: (First Amendment to 

Final Report). Project Number: STC/05/E276, EA05T1L001, 22156038. 

Unpublished study prepared by Stockbridge Technology Centre, Ltd. 100 p.

850.4025 Target area phytotoxicity

MRID Citation Reference

47874101 Rockliff, C. (2008) Evaluation of the Phytotoxicity of Sonalan 

(Enthalfluralin, 333g ai/l, EC) Seedling Emergence and Seedling Growth 

Test (Based on OECD Guideline 208 A) - Northern Europe, 2005: (First 

Amendment to Final Report). Project Number: STC/05/E276, 

EA05T1L001, 22156038. Unpublished study prepared by Stockbridge 

Technology Centre, Ltd. 100 p.

850-4150 Terrestrial plant toxicity, Tier 1 (vegetative vigor)

MRID Citation Reference
101

48509301 Breaux, N.; Douglas, M.; Chavez-Green, A.; et al. (2011) Dow 

AgroSciences Response to US EPAs Ethalfluralin Registration Review 

Docket EPA-OPP-2011-0094. Project Number: NTB053111/OCR. 

Unpublished study prepared by Dow AgroSciences, LLC. 29 p.

48915901 Sonalan HFP (Ethalfluralin, GF-1742, 360g as/L EC): Effects on 

Vegetative Vigor of Non-Target Terrestrial Plants (Tier II). 

850.4400 Aquatic plant toxicity test using Lemna spp. Tiers I and II

MRID Citation Reference

47866001 Hertl, J.; Breitwieser, H. (2009) Toxicity of Ethalfluralin Technical to 

the Aquatic Plant Lemna gibba in a Growth Inhibition Test. Project 

Number: 13052240. Unpublished study prepared by Institut fuer 

Biologische Analytik und Consulting IBACON. 76 p.

49086901 Softcheck, K. (2013) Ethalfluralin - 7-Day Toxicity Test with Duckweed 

(Lemna gibba). Project Number: 14050/6132, 120866. Unpublished 

study prepared by Smithers Viscient Laboratories. 105p.

141-1 Honey bee acute contact

MRID Citation Reference

41613914 Hoxter, K.; Jaber, M. (1990) The Acute Contact of Ethalfluralin to the Honey 

Bee: Lab Project Number: 151-114. Unpublished study prepared by Wildlife 

International Ltd. 30 p. 

850.6100 Environmental Chemistry Methods and Associated 

Independent Laboratory Validation

MRID Citation Reference

49385901 Garcia-Alix, M. (2012) Independent Laboratory Validaiton of an Analytical 

Method for the Determination of Ethalfluralin in Soil. Project Number: 

120138, CEMS/5394, 071040. Unpublished study prepared by CEM 

Analytical Services, Ltd. 70p.

49385902 Betson, S. (2012) Validation of an Analytical Method for the 

Determination of Ethalfluralin in Water. Project Number: 120814, 

CEMS/5608, 019/2002. Unpublished study prepared by CEM Analytical 

Services, Ltd. 123p.

49385903 Amic, S. (2013) Independent Laboratory Validation of an Analytical 

Method for the Determination of Ethalfluralin in Water by Gas 
102

Chromatography with Electron-Impact Mass Spectrometry Detection 

(GC/MS). Project Number: 130633, S13/01932, CEMS/5608. 

Unpublished study prepared by Eurofins Agroscience Services Chem 

SAS. 71p.

850.7100 Data reporting for environmental chemistry methods

MRID Citation Reference

48915801 Dial, G. (2007) Validation Report for Method GRM 07.07 - Determination 

of Residues of Benfluralin, Ethalfluralin, and Trifluralin in Soil by Gas 

Chromatography with Electron-Impact Mass Spectrometry Detection. 

Project Number: 071040, GRM/07/07. Unpublished study prepared by 

Dow AgroSciences, LLC. 51p.

Non Guideline Selections

94768 Karnak, R.E.; Kehr, C.C.; Hamelink, T.L; et al. (1980) The Toxicity of 

Compound 94961 (Ethalfluralin) to Earthworms in a 14- day Soil 

Incorporated Study: Study No. 6008-78. (Unpublished study received Feb 4, 

1982 under 1471-122; submitted by Elanco Products Co., Div. of Eli Lilly 

and Co., Indianapolis, Ind.; CDL:070677-M) 

94813 Kline, R.M.; Peloso, J.S.; Sieck, R.F.; et al. (1982) Microbial Interactions--

The Effect of Ethalfluralin on Nitrogen Fixation by Anabaena flos aquae. 

(Unpublished study received Feb 4, 1982 under 1471-122; submitted by 

Elanco Products Co., Div. of Eli Lilly and Co., Indianapolis, Ind.; 

CDL:070676-M) 

47899003 Effects of Ethalfluralin Technical on the Development of SedimentDwelling Larvae of Chironomus riparius in a Water-Sediment System.

48509301 Breaux, N.; Douglas, M.; Chavez-Green, A.; et al. (2011) Dow 

AgroSciences Response to US EPAs Ethalfluralin Registration Review 

Docket EPA-OPP-2011-0094. Project Number: NTB053111/OCR. 

Unpublished study prepared by Dow AgroSciences, LLC. 29 p.
103

Appendix C. Aquatic Exposure Modeling Inputs and Results

Surface Water Concentration Calculator (SWCC) Output Summary Table (all scenarios)

Scenario ID

Crops 

Represented

App. 

Date

App. 

Rate 

lb/A Peak Yr overall 4-day 21-day 60-day

Pore 

Water 

Peak

Pore 

Water 

21-day

Benthic 

Sdmnt. 

Peak

Benthic 

Sdmnt. 

21-day

ILCornSTD Soybean 10-Jun 1.31 4.61 0.11 0.09 3.17 1.36 0.62 0.19 0.15

KSCornStd Soybeam 10-Jun 1.31 5.94 0.16 0.12 4.27 2.25 0.93 0.30 0.24

MScornSTD Soybeam 10-Jun 1.31 4.69 0.20 0.12 3.33 1.90 1.01 0.23 0.17

MSsoybeanSTD Soybeam 10-Jun 1.31 4.51 0.17 0.11 3.32 1.82 0.89 0.22 0.16

NCcornESTD Soybeam 10-Jun 1.31 4.54 0.14 0.11 3.54 2.12 0.82 0.28 0.21

OHCornSTD Soybeam 10-Jun 1.31 4.51 0.12 0.10 3.23 1.39 0.65 0.21 0.16

PAcornSTD Soybeam 10-Jun 1.31 4.51 0.10 0.09 3.30 1.41 0.56 0.21 0.17

ILCornSTD Soybeam 25-Jun 1.31 4.52 0.11 0.09 3.29 1.54 0.63 0.22 0.17

KSCornStd Soybeam 25-Jun 1.31 4.56 0.16 0.11 3.61 1.67 0.81 0.24 0.17

MScornSTD Soybeam 25-Jun 1.31 4.59 0.20 0.13 3.49 1.96 0.97 0.20 0.16

MSsoybeanSTD Soybeam 25-Jun 1.31 4.51 0.17 0.11 3.42 1.88 0.89 0.19 0.15

NCcornESTD Soybeam 25-Jun 1.31 4.60 0.14 0.11 3.60 1.80 0.73 0.21 0.18

OHCornSTD Soybeam 25-Jun 1.31 5.23 0.12 0.10 3.66 1.67 0.63 0.24 0.18
104

PAcornSTD Soybeam 25-Jun 1.31 4.52 0.10 0.08 3.33 1.34 0.54 0.21 0.16

ILCornSTD Soybeam 10-Oct 1.31 4.57 0.12 0.10 3.26 1.31 0.61 0.23 0.19

KSCornStd Soybeam 10-Oct 1.31 5.35 0.15 0.11 3.82 1.60 0.82 0.27 0.22

MScornSTD Soybeam 10-Oct 1.31 6.51 0.25 0.18 4.71 2.60 1.27 0.37 0.30

MSsoybeanSTD Soybeam 10-Oct 1.31 6.05 0.22 0.15 4.30 2.34 1.06 0.33 0.27

NCcornESTD Soybeam 10-Oct 1.31 4.83 0.15 0.12 3.50 1.70 0.82 0.28 0.23

OHCornSTD Soybeam 10-Oct 1.31 4.51 0.15 0.11 3.36 1.35 0.68 0.23 0.19

PAcornSTD Soybeam 10-Oct 1.31 4.52 0.11 0.10 3.31 1.41 0.59 0.24 0.20

ILCornSTD Soybeam 25-Oct 1.31 4.60 0.13 0.10 3.28 1.37 0.63 0.25 0.22

KSCornStd Soybeam 25-Oct 1.31 4.52 0.14 0.11 3.30 1.74 0.75 0.30 0.26

MScornSTD Soybeam 25-Oct 1.31 5.42 0.26 0.18 4.21 2.11 1.36 0.38 0.34

MSsoybeanSTD Soybeam 25-Oct 1.31 5.06 0.22 0.16 3.99 1.96 1.21 0.35 0.29

NCcornESTD Soybeam 25-Oct 1.31 5.61 0.17 0.12 3.87 2.10 0.94 0.37 0.32

OHCornSTD Soybeam 25-Oct 1.31 4.51 0.17 0.13 3.43 1.66 0.78 0.29 0.25

PAcornSTD Soybeam 25-Oct 1.31 4.63 0.12 0.10 3.34 1.37 0.61 0.25 0.22

ND Canola Sunflower 15-May 1.70 5.91 0.10 0.09 4.11 1.42 0.59 0.29 0.24

ND Canola Sunflower 10-Jun 1.70 5.85 0.11 0.09 4.12 1.59 0.63 0.28 0.22

ND Canola Sunflower 10-Oct 1.70 5.85 0.11 0.09 4.08 1.50 0.57 0.30 0.26

ND Canola Sunflower 25-Oct 1.70 5.85 0.13 0.11 4.13 1.49 0.63 0.32 0.28 50.88 44.68

KS corn Sunflower 15-May 1.70 6.10 0.20 0.15 4.56 1.90 1.06 0.30 0.25
105

KS corn Sunflower 10-Jun 1.70 7.69 0.21 0.16 5.53 2.92 1.20 0.38 0.31

KS corn Sunflower 10-Oct 1.70 6.94 0.19 0.14 4.95 2.07 1.06 0.35 0.28

KS corn Sunflower 25-Oct 1.70 5.85 0.19 0.14 4.27 2.25 0.97 0.38 0.34 60.90 54.38

FL Cucu Cucurbits 15-Oct 1.70 8.49 0.24 0.15 5.68 2.59 1.33 0.32 0.23 51.52 37.05

FL Cucu Cucurbits 30-Oct 1.70 12.50 0.25 0.15 8.34 3.55 1.36 0.49 0.33 77.59 52.79

FL Cucu Cucurbits 30-Oct 0.75 5.52 0.11 0.06 3.68 1.57 0.60 0.15 34.23 23.29 0.00

FL Cucu Cucurbits 30-Oct 1.13 8.28 0.16 0.10 5.55 2.36 0.91 0.33 0.22 51.68 35.14

NC Peanut Peanut 1-May 1.15 4.12 0.11 0.09 3.32 1.37 0.57 0.23 0.19 36.252 30.05

MI Beans Dry beans 15-May 1.69 5.90 0.13 0.11 4.28 1.69 0.71 0.31 0.26 49.29 41.82

ID Npotato Potatoes 10-May 1.03 3.54 0.07 0.06 2.56 1.01 0.40 0.19 0.16 30.37 25.92

CA alfalfa-OP

Alfalfa, 

clover 10-Jan 1.69 5.81 0.15 0.13 4.44 2.09 0.96 0.40 0.37 63.92 57.88

Maximum 12.50 0.26 0.18 8.34 3.55 1.36 0.49 34.23 77.59 57.88

Minimum 3.54 0.07 0.06 2.56 1.01 0.40 0.15 0.15 23.29 0.00
106

Surface Water Modeling with the Surface Water Concentration Calculator

(SWCC)

1. Sample Input / Output reports generated by SWCC – Comparison of 1 vs. 4 cm incorp. –

Fl Cucumber Scenario

Table 1. Estimated Environmental Concentrations (ppb) for Ethalfluralin Fl cucumber 

scenario, Oct. 30 annual applications, comparison of conservative at 1 cm versus 

incorporated to 4 cm depth assumptions.

EEC Exposure Duration At 1 cm

depth

Incorp. To 4 

cm depth

Peak (1-in-10 yr) 12.4 8.92

4-day Avg (1-in-10 yr) 8.29 6.13

21-day Avg (1-in-10 yr) 3.50 2.72

60-day Avg (1-in-10 yr) 1.34 1.03

365-day Avg (1-in-10 yr) 0.244 0.184

Entire Simulation Mean 0.146 0.120

a. Application fully Incorporated to 4 cm.

Estimated Environmental Concentrations for Ethalfluralin are presented in Table 1 for the 

USEPA standard pond with the FLcucumberSTD field scenario. A graphical presentation of the 

year-to-year peaks is presented in Figure 1. These values were generated with the Surface Water 

Concentration Calculator (SWCC Version 1.106). Critical input values for the model are 

summarized in Tables 2 and 3.

This model estimates that about 1.2% of Ethalfluralin applied to the field eventually reaches the 

water body. The main mechanism of transport from the field to the water body is by spray drift 

(53.3% of the total transport), followed by runoff (43.6%) and erosion (3.18%).

In the water body, pesticide dissipates with an effective water column half-life of 4.7 days. (This 

value does not include dissipation by transport to the benthic region; it includes only processes 

that result in removal of pesticide from the complete system.) The main source of dissipation in 

the water column is volatilization (effective average half-life = 6.2 days) followed by photolysis 

(22.6 days) and metabolism (104.3 days).

In the benthic region, pesticide dissipates (5.1 days). The main source of dissipation in the 

benthic region is metabolism (effective average half-life = 5.1 days). The vast majority of the 

pesticide in the benthic region (99.77%) is sorbed to sediment rather than in the pore water.
107

Table 1. Estimated Environmental Concentrations (ppb) for Ethalfluralin.

Peak (1-in-10 yr) 8.92

4-day Avg (1-in-10 yr) 6.13

21-day Avg (1-in-10 yr) 2.72

60-day Avg (1-in-10 yr) 1.03

365-day Avg (1-in-10 yr) 0.184

Entire Simulation Mean 0.120

Table 2. Summary of Model Inputs for Ethalfluralin.

Scenario FLcucumberSTD

Cropped Area Fraction 1

Koc (ml/g) 3957

Water Half-Life (days) @ 25 °C 97

Benthic Half-Life (days) @ 25 °C 4.75

Photolysis Half-Life (days) @ 40 

°Lat

0.263

Hydrolysis Half-Life (days) 0

Soil Half-Life (days) @ 25 °C 48.5

Foliar Half-Life (days) 0

Molecular Wt 333.27

Vapor Pressure (torr) 8.3e-5

Solubility (mg/l) 0.3

Table 3. Application Schedule for Ethalfluralin.

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift

10/30 Incorporated to 4 

cm

1.91 0.99 0.062

Figure 1. Yearly Peak Concentrations
108

a. Application fully placed at a 1 cm depth (Assumption used in EEC 

calculations for all scenarios)

Summary of Water Modeling of Ethalfluralin 48asm no vol 4cm-ap 

and the USEPA Standard Pond FL cucumber dept 1 cm

Estimated Environmental Concentrations for Ethalfluralin 48asm no vol 4cm-ap are presented in 

Table 1 for the USEPA standard pond with the FLcucumberSTD field scenario. A graphical 

presentation of the year-to-year peaks is presented in Figure 1. These values were generated with 

the Pesticide Water Calculator (PWC), Version 1.52. Critical input values for the model are 

summarized in Tables 2 and 3.

This model estimates that about 1.4% of Ethalfluralin 48asm no vol 4cm-ap applied to the field 

eventually reaches the water body. The main mechanism of transport from the field to the water 

body is by runoff (55.6% of the total transport) followed by spray drift (44.4%).

In the water body, pesticide dissipates with an effective water column half-life of 4.7 days. (This 

value does not include dissipation by transport to the benthic region; it includes only processes 

that result in removal of pesticide from the complete system.) The main source of dissipation in 

the water column is volatilization (effective average half-life = 6.3 days) followed by photolysis 

(22.6 days) and metabolism (104.3 days).

In the benthic region, pesticide dissipates (5.1 days). The main source of dissipation in the 

benthic region is metabolism (effective average half-life = 5.1 days). The vast majority of the 

pesticide in the benthic region (99.77%) is sorbed to sediment rather than in the pore water.

Table 1. Estimated Environmental Concentrations (ppb) for Ethalfluralin 48asm no vol 

4cm-ap.

Peak (1-in-10 yr) 12.4
109

4-day Avg (1-in-10 yr) 8.29

21-day Avg (1-in-10 yr) 3.50

60-day Avg (1-in-10 yr) 1.34

365-day Avg (1-in-10 yr) 0.244

Entire Simulation Mean 0.146

Table 2. Summary of Model Inputs for Ethalfluralin 48asm no vol 4cm-ap.

Scenario FLcucumberSTD

Cropped Area Fraction 1

Koc (ml/g) 3957

Water Half-Life (days) @ 25 °C 97

Benthic Half-Life (days) @ 25 °C 4.75

Photolysis Half-Life (days) @ 40 

°Lat

0.263

Hydrolysis Half-Life (days) 0

Soil Half-Life (days) @ 25 °C 48

Foliar Half-Life (days) 0

Molecular Weight 333.27

Vapor Pressure (torr) 8.2E-5

Solubility (mg/l) 0.3

Henry's Constant 0.0049

Table 3. Application Schedule for Ethalfluralin 48asm no vol 4cm-ap.

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift

10/30 Placed at a depth 

of 4 cm

1.905 .99 .062

Figure 1. Yearly Peak Concentrations
110

2. Sample Output Summary files – SWCC and PWC

SWCC

1. Sunflower and other Oilseed Crop Use Exposure Asssessment – KScorn Scenario 

\

File Name: SWCC_ethalfl-RR2015_KSCorn_Reserv+Pond_Jun10app (rep sunflower) 

48.5dASM-97dWC_KSCornStd_Pond_Parent.txt

 

Variable Volume Water Model, SWCC Compatible Version

*******************************************

Performed on: 1/19/2016 at 18:25

Peak 1-in-10 = 7.69 ppb

Chronic 1-in-10 = 0.211 ppb

Simulation Avg = 0.155 ppb

4-day avg 1-in-10 = 5.51 ppb

21-day avg 1-in-10 = 2.90 ppb

60-day avg 1-in-10 = 1.19 ppb

90-day avg 1-in-10 = 0.800 ppb

Benthic Pore Water Peak 1-in-10 = 0.381 ppb

Benthic Pore Water 21-day avg 1-in-10 = 0.302 ppb
111

Benthic Conversion Factor = 159. -Pore water (ug/L) to (total mass, ug)/(dry sed 

mass,kg)

Benthic Mass Fraction in Pore Water = 0.233E-02

YEAR Peak 4-day 21-day 60-day 90-day Yearly Avg Benthic Pk Benthic 21-day

 1 5.85E+00 4.20E+00 1.50E+00 7.49E-01 5.12E-01 1.43E-01 2.55E-01 1.79E-01

 2 5.85E+00 3.92E+00 1.57E+00 6.79E-01 5.47E-01 1.45E-01 2.14E-01 1.66E-01

 3 5.85E+00 4.00E+00 1.48E+00 6.62E-01 4.47E-01 1.11E-01 2.36E-01 1.64E-01

 4 5.85E+00 4.65E+00 2.09E+00 7.66E-01 6.25E-01 1.70E-01 3.21E-01 2.30E-01

 5 5.85E+00 4.14E+00 1.77E+00 8.12E-01 5.68E-01 1.57E-01 2.36E-01 1.81E-01

 6 7.73E+00 5.56E+00 2.47E+00 9.19E-01 6.48E-01 1.60E-01 3.81E-01 2.76E-01

 7 9.28E+00 6.83E+00 4.35E+00 1.74E+00 1.16E+00 3.05E-01 5.55E-01 4.48E-01

 8 7.04E+00 4.64E+00 1.79E+00 1.04E+00 7.87E-01 2.06E-01 2.96E-01 2.10E-01

 9 7.73E+00 5.62E+00 2.65E+00 9.99E-01 6.69E-01 1.71E-01 3.77E-01 3.07E-01

10 6.59E+00 4.50E+00 1.52E+00 5.54E-01 3.71E-01 1.11E-01 2.55E-01 1.74E-01

11 6.65E+00 4.50E+00 1.58E+00 6.04E-01 4.03E-01 1.12E-01 2.64E-01 1.81E-01

12 5.85E+00 3.45E+00 1.18E+00 5.31E-01 3.85E-01 1.12E-01 1.86E-01 1.25E-01

13 5.85E+00 3.60E+00 1.14E+00 8.69E-01 6.14E-01 2.06E-01 2.03E-01 1.33E-01

14 5.85E+00 4.02E+00 1.38E+00 5.67E-01 4.22E-01 1.17E-01 2.30E-01 1.60E-01

15 6.36E+00 4.21E+00 1.41E+00 5.08E-01 3.47E-01 1.02E-01 2.35E-01 1.60E-01

16 5.85E+00 3.54E+00 1.09E+00 4.29E-01 2.87E-01 7.44E-02 1.89E-01 1.24E-01

17 6.90E+00 4.96E+00 3.19E+00 1.25E+00 9.35E-01 2.49E-01 4.16E-01 3.03E-01

18 5.85E+00 3.40E+00 1.57E+00 6.40E-01 4.41E-01 1.30E-01 1.98E-01 1.62E-01

19 5.85E+00 4.04E+00 1.64E+00 9.01E-01 6.59E-01 1.75E-01 2.36E-01 1.73E-01

20 5.85E+00 3.90E+00 1.19E+00 4.77E-01 3.58E-01 1.11E-01 2.06E-01 1.28E-01

21 7.05E+00 5.12E+00 2.11E+00 1.07E+00 7.44E-01 1.97E-01 2.86E-01 2.13E-01

22 5.85E+00 4.25E+00 1.86E+00 9.42E-01 6.79E-01 1.75E-01 2.73E-01 2.25E-01

23 5.85E+00 3.90E+00 1.57E+00 6.08E-01 4.06E-01 1.14E-01 2.31E-01 1.74E-01

24 7.33E+00 4.96E+00 2.92E+00 1.20E+00 8.01E-01 2.12E-01 3.73E-01 2.92E-01

25 5.85E+00 3.96E+00 1.40E+00 6.82E-01 5.18E-01 1.58E-01 2.27E-01 1.59E-01

26 5.85E+00 3.87E+00 1.46E+00 6.48E-01 5.01E-01 1.38E-01 2.22E-01 1.57E-01

27 5.85E+00 4.55E+00 1.85E+00 7.31E-01 5.45E-01 1.42E-01 2.55E-01 1.84E-01

28 5.85E+00 4.01E+00 1.49E+00 6.71E-01 4.57E-01 1.16E-01 2.21E-01 1.51E-01

29 5.85E+00 4.03E+00 1.72E+00 8.15E-01 6.30E-01 1.89E-01 2.31E-01 1.83E-01

30 5.89E+00 3.71E+00 1.51E+00 6.71E-01 5.14E-01 1.33E-01 2.31E-01 1.65E-01

******************************************************************************

**********************

Effective compartment halflives averaged over simulation duration:

zero washout 0

water col metab halflife (days) = 186.982755893926 

zero hydrolysis 0

photolysis halflife (days) = 30.8989226773054 

volatile halflife (days) = 8.71834121390727 

total water col halflife (days) = 6.56114624506848 
112

zero burial 0

benthic metab halflife (days) = 9.15637206697060 

zero benthic hydrolysis 0

total benthic halflife (days) = 9.15637206697060 

***********************************************************************

Fractional Contribution of Transport Processes to Waterbody & Total Mass (kg):

Due to Runoff = 0.5039 3.599 

Due to Erosion = 0.0000 0.000 

Due to Drift = 0.4961 3.543 

***********************************************************************

Flow in/out Characteristics of Waterbody:

Average Daily Runoff Into Waterbody (m3/s) = 8.385461856625667E-004

Baseflow Into Waterbody (m3/s) = 0.000000000000000E+000

Average Daily Flow Out of Waterbody (m3/s) = 8.385461856625857E-004

***********************************************************************

Inputs:

 3957. = oc partitioning coefficient

 97.00 = water column half Life

 25.00 = reference temp for water column degradation

 4.750 = benthic Half Life

 25.00 = Reference temp for benthic degradation

 2.000 = Q ten value

 0.2630 = photolysis half life

 40.00 = reference latitude for photolysis study

 0.000 = hydrolysis half life

 333.3 = molecular wt

 0.8200E-04 = vapor pressure

 0.3000 = solubility

 0.1000E+06 = field area

 0.1000E+05 = water body area

 2.000 = initial depth

 2.000 = maximum depth

 2 1=vvwm, 2=usepa pond, 3 = usepa reservoir, 4 = const vol no flow, 5 = const vol 

w/flow 

F T = burial, else no burial

 0.1000E-07 = mass transfer coefficient 

 0.5000 = PRBEN

 0.5000E-01 = benthic compartment depth

 0.5000 = benthic porosity

 1.350 = benthic bulk density

 0.4000E-01 = OC frcation in benthic sediment

 5.000 = DOC in benthic compartment

 0.6000E-02 = benthic biomass

 1.190 = DFAC

 30.00 = SS
113

 0.5000E-02 = chlorophyll

 0.4000E-01 = OC frcation in water column SS

 5.000 = DOC in water column

 0.4000 = biomass in water column

FRACTION AREA CROPPED = 1.00000000000000 

PWC Sample Output File (with volatilization invoked)

ariable Volume Water Model, Version 1.02000000000000 

*******************************************

Performed on: 2/23/2016 at 13:36

Peak 1-in-10.0 = 7.74 ppb

Chronic 1-in-10.0 = 0.219 ppb

Simulation Avg = 0.161 ppb

4-d avg 1-in-10.0 = 5.60 ppb

21-d avg 1-in-10.0 = 2.98 ppb

60-d avg 1-in-10.0 = 1.22 ppb

90-d avg 1-in-10.0 = 0.825 ppb

1-d avg 1-in-10.0 = 7.02 ppb

Benthic Pore Water Peak 1-in-10.0 = 0.392 ppb

Benthic Pore Water 21-d avg 1-in-10.0 = 0.309 ppb

Benthic Conversion Factor = 159. -Pore water (ug/L) to (total mass, ug)/(dry sed 

mass,kg)

Benthic Mass Fraction in Pore Water = 0.233E-02

YEAR Peak 4-day 21-day 60-day 90-day Yearly Avg Benthic Pk Benthic 21-day

 1 5.85E+00 4.28E+00 1.58E+00 7.80E-01 5.33E-01 1.50E-01 2.64E-01 1.87E-01

 2 5.85E+00 3.95E+00 1.61E+00 6.95E-01 5.58E-01 1.49E-01 2.17E-01 1.70E-01

 3 5.85E+00 4.05E+00 1.53E+00 6.80E-01 4.58E-01 1.15E-01 2.42E-01 1.69E-01

 4 5.85E+00 4.72E+00 2.17E+00 7.95E-01 6.45E-01 1.77E-01 3.28E-01 2.38E-01

 5 5.85E+00 4.18E+00 1.82E+00 8.35E-01 5.84E-01 1.62E-01 2.40E-01 1.86E-01

 6 7.84E+00 5.65E+00 2.57E+00 9.57E-01 6.73E-01 1.67E-01 3.93E-01 2.86E-01

 7 9.35E+00 6.97E+00 4.51E+00 1.81E+00 1.21E+00 3.19E-01 5.74E-01 4.64E-01

 8 7.04E+00 4.76E+00 1.89E+00 1.07E+00 8.13E-01 2.13E-01 3.09E-01 2.21E-01

 9 7.78E+00 5.71E+00 2.77E+00 1.05E+00 7.02E-01 1.80E-01 3.91E-01 3.20E-01

10 6.67E+00 4.64E+00 1.62E+00 5.89E-01 3.94E-01 1.17E-01 2.67E-01 1.84E-01

11 6.65E+00 4.58E+00 1.64E+00 6.28E-01 4.19E-01 1.18E-01 2.72E-01 1.87E-01

12 5.85E+00 3.52E+00 1.22E+00 5.49E-01 3.97E-01 1.17E-01 1.92E-01 1.30E-01

13 5.85E+00 3.72E+00 1.22E+00 8.94E-01 6.31E-01 2.16E-01 2.13E-01 1.41E-01

14 5.85E+00 4.07E+00 1.43E+00 5.85E-01 4.35E-01 1.22E-01 2.35E-01 1.65E-01

15 6.36E+00 4.28E+00 1.46E+00 5.29E-01 3.60E-01 1.08E-01 2.41E-01 1.66E-01

16 5.85E+00 3.66E+00 1.16E+00 4.57E-01 3.05E-01 7.99E-02 1.98E-01 1.32E-01

17 6.97E+00 5.03E+00 3.25E+00 1.27E+00 9.51E-01 2.54E-01 4.23E-01 3.09E-01

18 5.85E+00 3.53E+00 1.64E+00 6.68E-01 4.60E-01 1.36E-01 2.08E-01 1.70E-01
114

19 5.85E+00 4.11E+00 1.71E+00 9.33E-01 6.80E-01 1.81E-01 2.43E-01 1.81E-01

20 5.85E+00 3.96E+00 1.23E+00 4.91E-01 3.65E-01 1.16E-01 2.10E-01 1.32E-01

21 7.10E+00 5.20E+00 2.19E+00 1.10E+00 7.63E-01 2.04E-01 2.95E-01 2.21E-01

22 5.85E+00 4.32E+00 1.95E+00 9.86E-01 7.08E-01 1.84E-01 2.82E-01 2.36E-01

23 5.85E+00 4.01E+00 1.67E+00 6.45E-01 4.31E-01 1.23E-01 2.43E-01 1.84E-01

24 7.39E+00 5.06E+00 3.01E+00 1.24E+00 8.26E-01 2.20E-01 3.84E-01 3.00E-01

25 5.85E+00 4.02E+00 1.46E+00 7.02E-01 5.32E-01 1.64E-01 2.32E-01 1.65E-01

26 5.85E+00 3.93E+00 1.51E+00 6.67E-01 5.13E-01 1.42E-01 2.28E-01 1.63E-01

27 5.86E+00 4.58E+00 1.88E+00 7.43E-01 5.52E-01 1.44E-01 2.58E-01 1.87E-01

28 5.85E+00 4.06E+00 1.52E+00 6.86E-01 4.66E-01 1.19E-01 2.25E-01 1.55E-01

29 5.85E+00 4.09E+00 1.78E+00 8.40E-01 6.47E-01 1.96E-01 2.36E-01 1.89E-01

30 5.89E+00 3.82E+00 1.60E+00 7.00E-01 5.34E-01 1.39E-01 2.42E-01 1.73E-01

******************************************************************************

**********************

Effective compartment halflives averaged over simulation duration:

zero washout 0

water col metab halflife (days) = 186.982755893926 

zero hydrolysis 0

photolysis halflife (days) = 30.8989226773054 

volatile halflife (days) = 11.0708851226495 

total water col halflife (days) = 7.81013932066613 

zero burial 0

benthic metab halflife (days) = 9.15637206697060 

zero benthic hydrolysis 0

total benthic halflife (days) = 9.15637206697060 

***********************************************************************

Fractional Contribution of Transport Processes to Waterbody & Total Mass (kg):

Due to Runoff = 0.5042 3.603 

Due to Erosion = 0.0000 0.1157E-26

Due to Drift = 0.4958 3.543 

***********************************************************************

Flow in/out Characteristics of Waterbody:

Average Daily Runoff Into Waterbody (m3/s) = 8.391564781242711E-004

Baseflow Into Waterbody (m3/s) = 0.000000000000000E+000

Average Daily Flow Out of Waterbody (m3/s) = 8.391564781242700E-004

***********************************************************************

Inputs:

 3957. = oc partitioning coefficient

 97.00 = water column half Life

 25.00 = reference temp for water column degradation

 4.750 = benthic Half Life

 25.00 = Reference temp for benthic degradation

 2.000 = Q ten value
115

 0.2630 = photolysis half life

 40.00 = reference latitude for photolysis study

 0.000 = hydrolysis half life

 333.3 = molecular wt

 0.8200E-04 = vapor pressure

 0.3000 = solubility

 0.1000E+06 = field area

 0.1000E+05 = water body area

 2.000 = initial depth

 2.000 = maximum depth

 2 1=vvwm, 2=usepa pond, 3 = usepa reservoir, 4 = const vol no flow, 5 = const vol 

w/flow 

F T = burial, else no burial

 0.1000E-07 = mass transfer coefficient 

 0.5000 = PRBEN

 0.5000E-01 = benthic compartment depth

 0.5000 = benthic porosity

 1.350 = benthic bulk density

 0.4000E-01 = OC frcation in benthic sediment

 5.000 = DOC in benthic compartment

 0.6000E-02 = benthic biomass

 1.190 = DFAC

 30.00 = SS

 0.5000E-02 = chlorophyll

 0.4000E-01 = OC frcation in water column SS

 5.000 = DOC in water column

 0.4000 = biomass in water column

FRACTION AREA CROPPED = 1.00000000000000 

Sample SWCC Input Files

2. Sunflower and other Oilseed Crop Use Exposure Asssessment – KScorn Scenario 

File Name: SWCC_ethalfl-RR2015_KSCorn_Reserv+Pond_Jun10app (rep sunflower) 

48.5dASM-97dWC.SWI

Ethalfluralin 

1

True

3957,,,

97,,,

25,,,

4.75,,,

25,,,
116

0.263,,,

40,,,

0,,,

48.5,,,

25,

0,,,

333.27,,,

8.2E-5,,,

0.3,,,

0,0,

0,0,

0,0,

0,0,

0,0,

0,0,

2

1

10,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

6,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

1.905,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

False

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

4,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.99,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.062,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.99,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.0661,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

1,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

True

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

KSCornStd

C:\Models\Inputs\Metfiles\W13996.dvf

True,True,False,False,False

False,30

False

10000
117

12

4.2

4.8

1E-08

0.5

0.05

0.5

1.35

0.04 5

0.006

1.19

30

0.005

0.04 5

0.4

False

1.0,1.0

10597

20

10

90,300

100

0.25 1

0.72

0.36

17.5 0

0.37

0.58

0.5 3

3.4

600 4

10,8,8,66,

1.3,1.3,1.3,1.29,
118

0.364,0.364,0.274,0.32,

0.139,0.139,0.224,0.229,

1.74,1.74,1.3,0.87,

100,4,4,33,

,,,,

,,,,

False

29

10,16,1,16,1,16,1,16,1,16,1,5,16,1,16,1,16,1,16,1,16,1,16,1,10,16,20,25,1,,,,,,,,,,,,,,,,,,,,,,,,

5,5,6,6,7,7,8,8,9,9,10,10,10,11,11,12,12,1,1,2,2,3,3,4,4,4,4,4,5,,,,,,,,,,,,,,,,,,,,,,,,

88,88,88,88,88,88,88,88,88,88,88,88,88,94,94,94,94,94,94,94,94,94,94,94,94,94,94,94,94,,,,,,,,,,,,

,,,,,,,,,,,,

.189,.195,.151,.122,.101,.107,.115,.122,.130,.150,.178,.099,.106,.096,.084,.087,.089,.038,.038,.0

39,.039,.040,.042,.044,.090,.094,.160,.184,.189,,,,,,,,,,,,,,,,,,,,,,,,

.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.023,.0

23,.023,.023,.023,.023,.023,.023,.023,.023,.023,,,,,,,,,,,,,,,,,,,,,,,,

2.0,1.55,0.266,

0.1,0,

False

3. Cucurbits Use Exposure Asssessment – FL Cucumber Scenario (Oct. 30 application 

date)

File Name: SWCC_ethalfl-RR2015_FLcucu_Reserv+Pond_Oct30 app (rep 

Cucurb)48.5dASMH2O97d.SWI 

Ethalfluralin B test

1

True

3957,,,

97,,,

25,,,

4.75,,,

25,,,

0.263,,,

40,,,

0,,,

48.5,,,

25,

0,,,

333.27,,,

8.2E-5,,,

0.3,,,
119

0,0,

0,0,

0,0,

0,0,

0,0,

0,0,

2

1

30,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

10,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

1.905,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

False

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

4,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.99,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.062,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.99,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.0661,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

1,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

True

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

FLcucumberSTD

C:\Models\Inputs\Metfiles\W12844.dvf

True,True,False,False,False

False,30

False

10000

12

4.2

4.8

1E-08

0.5

0.05

0.5

1.35

0.04
120

5

0.006

1.19

30

0.005

0.04 5

0.4

False

1.0,1.0

16

105

12

10

12

50,30

80

0.15 1

0.78 0

32.5 0

0.03

0.2 141

600 3

10,62,28,

1.65,1.65,1.7,

0.073,0.073,0.211,

0.023,0.023,0.091,

1.16,1.16,0.174,

100,31,7,

,,,

,,,

False
121

27

16,1,16,1,16,1,16,1,16,1,16,1,16,1,15,16,25,1,16,1,16,1,10,16,1,16,1,,,,,,,,,,,,,,,,,,,,,,,,,,

10,11,11,12,12,1,1,2,2,3,3,4,4,5,5,5,5,6,6,7,7,8,8,8,9,9,10,,,,,,,,,,,,,,,,,,,,,,,,,,

87,87,87,87,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,91,,,,,,,,,,,,,,,,,,,,,,

,,,,

.683,.715,.743,.768,.793,.813,.830,.846,.859,.870,.878,.881,.881,.880,.836,.849,.938,.840,.572,.2

85,.177,.162,.210,.291,.422,.547,.636,,,,,,,,,,,,,,,,,,,,,,,,,,

.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.011,.0

11,.011,.011,.011,.011,.011,.011,.011,,,,,,,,,,,,,,,,,,,,,,,,,,

2.0,1.55,0.266,

0.1,0,

False

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
122

Appendix D. Sample TREX Files

Upper Bound Kenaga Residues For RQ Calculation

Chemical Name: Ethalfluralin

 Use 24

 Formulation 0

Application Rate 1.69 lbs a.i./acre

Half-life 35 days 

Application Interval 0 days

Maximum # Apps./Year 1

Length of Simulation 1 year

Variable application rates? no

Endpoints

Avian

Redwinged blackbird LD50 (mg/kg-bw) 2000.00

Bobwhite quail LC50 (mg/kg-diet) 5000.00

Bobwhite quail NOAEL(mg/kg-bw) 0.00

Mallard duck NOAEC (mg/kg-diet) 1000.00

Mammals

LD50 (mg/kg-bw) 5000.00

LC50 (mg/kg-diet) 0.00

NOAEL (mg/kg-bw) 61.00

NOAEC (mg/kg-diet) 1220.00

Dietary-based EECs (ppm) Kenaga

Values

Short Grass 405.60

Tall Grass 185.90

Broadleaf plants 228.15

Fruits/pods/seeds 25.35

Arthropods 158.86
123

Dose-based EECs (mg/kg-bw)

Avian Classes and Body Weights (grams)

small mid large

20 100 1000

Short Grass 461.94 263.42 117.94

Tall Grass 211.72 120.73 54.05

Broadleaf plants 259.84 148.17 66.34

Fruits/pods 28.87 16.46 7.37

Arthropods 180.93 103.17 46.19

Seeds 6.42 3.66 1.64

Dose-based RQs 

(Dose-based EEC/adjusted LD50)

Avian Acute RQs

Size Class (grams)

20 100 1000

Short Grass 0.27 0.12 0.04

Tall Grass 0.13 0.06 0.02

Broadleaf plants 0.15 0.07 0.02

Fruits/pods 0.02 0.01 0.00

Arthropods 0.11 0.05 0.02

Seeds 0.00 0.00 0.00

Dietary-based RQs 

(Dietary-based EEC/LC50 or 

NOAEC)

RQs

Acute Chronic

Short Grass 0.08 0.41

Tall Grass 0.04 0.19

Broadleaf plants 0.05 0.23

Fruits/pods/seeds 0.01 0.03

Arthropods 0.03 0.16

Mammalian Classes and Body weight

(grams)
124

Dose-Based EECs 

(mg/kg-bw) 15 35 1000

Short Grass 386.71 267.27 61.97

Tall Grass 177.24 122.50 28.40

Broadleaf plants 217.52 150.34 34.86

Fruits/pods 24.17 16.70 3.87

Arthropods 151.46 104.68 24.27

Seeds 5.37 3.71 0.86

Dose-based RQs 

(Dose-based EEC/LD50 or NOAEL) small medium large

Chronic Chronic Chronic

Short Grass 2.88 2.46 1.32

Tall Grass 1.32 1.13 0.61

Broadleaf plants 1.62 1.39 0.74

Fruits/pods 0.18 0.15 0.08

Arthropods 1.13 0.97 0.52

Seeds 0.04 0.03 0.02

Dietary-based RQs 

(Dietary-based EEC/LC50 or 

NOAEC)

Mammal RQs

Acute Chronic

Short Grass #DIV/0! 0.33

Tall Grass #DIV/0! 0.15

Broadleaf plants #DIV/0! 0.19

Fruits/pods/seeds #DIV/0! 0.02

Arthropods #DIV/0! 0.13

Appendix E. Sample TerrPlant Files

Table 1. Chemical Identity.

Chemical Name Ethalfluralin
125

PC code 113101

Use alfalfa

Application Method Spray

Application Form Ground Application

Solubility in Water (ppm) 0.3

Table 2. Input parameters used to derive EECs.

Input Parameter Symbol Value Units

Application Rate A 1.3 y

Incorporation I 2 none

Runoff Fraction R 0.01 none

Drift Fraction D 0 none

Table 3. EECs for Ethalfluralin. Units in y.

Description Equation EEC

Runoff to dry areas (A/I)*R 0.0065

Runoff to semi-aquatic areas (A/I)*R*10 0.065

Spray drift A*D 0

Total for dry areas ((A/I)*R)+(A*D) 0.0065

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.065

Table 4. Plant survival and growth data used for RQ derivation. Units are in y.

Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 0.0183 0.00195 0.212 0.053

Dicot 0.139 0.105 0.27 0.027

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to Ethalfluralin through runoff 

and/or spray drift.*

Plant Type Listed Status Dry Semi-Aquatic Spray Drift
126

Monocot non-listed 0.36 3.55 <0.1

Monocot listed 3.33 33.33 <0.1

Dicot non-listed <0.1 0.47 <0.1

Dicot listed <0.1 0.62 <0.1

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.
127

Appendix F. Sample KABAM Files

Table 11. Estimated concentrations of Ethalfluralin in ecosystem components.

Ecosystem Component

Total 

concentration 

(μg/kg-ww)

Lipid 

normalized 

concentration 

(μg/kg-lipid)

Contribution 

due to diet 

(μg/kg-ww)

Contribution 

due to 

respiration 

(μg/kg-ww)

Water (total)* 13 N/A N/A N/A

Water (freely dissolved)* 13 N/A N/A N/A

Sediment (pore water)* 0 N/A N/A N/A

Sediment (in solid)** 52 N/A N/A N/A

Phytoplankton 72,690 3634482 N/A 72,689.64

Zooplankton 56,920 1897330 2,222.15 54,697.75

Benthic Invertebrates 61,641 2054701 5,607.68 56,033.37

Filter Feeders 40,471 2023530 3,612.90 36,857.70

Small Fish 94,288 2357210 24,355.55 69,932.85

Medium Fish 115,675 2891869 48,653.60 67,021.15

Large Fish 174,190 4354746 107,805.01 66,384.81

* Units: μg/L; **Units: μg/kg-dw

Table 12. Total BCFand BAF values of Ethalfluralin in aquatic 

trophic levels.

Trophic Level

Total BCF 

(μg/kg-ww)/(μg/L)

Total BAF 

(μg/kg-ww)/(μg/L)

Phytoplankton 6184 5815

Zooplankton 4407 4554

Benthic 

Invertebrates 4578 4931

Filter Feeders 3010 3238

Small Fish 5889 7543

Medium Fish 5889 9254

Large Fish 6191 13935

Table 13. Lipid-normalized BCF, BAF, BMF and BSAF values of Ethalfluralin in aquatic 

trophic levels.

Trophic Level

BCF 

(μg/kglipid)/(μg/L)

BAF 

(μg/kglipid)/(μg/L)

BMF 

(μg/kglipid)/(μg/kglipid)

BSAF 

(μg/kglipid)/(μg/kgOC)

Phytoplankton 309225 290759 N/A 2782

Zooplankton 146889 151786 0.52 1452
128

Benthic Invertebrates 152604 164376 1.13 1573

Filter Feeders 150475 161882 1.11 1549

Small Fish 147235 188577 1.19 1804

Medium Fish 147235 231350 1.31 2214

Large Fish 154769 348380 1.51 3334

Table 14. Calculation of EECs for mammals and birds consuming fish contaminated by Ethalfluralin.

Wildlife Species Biological Parameters EECs (pesticide intake)

Body

Weight

(kg)

Dry Food 

Ingestion 

Rate (kg-dry 

food/kgbw/day)

Wet Food 

Ingestion 

Rate (kg-wet 

food/kgbw/day)

Drinking 

Water

Intake

(L/d)

Dose 

Based 

(mg/kgbw/d)

Dietary 

Based 

(ppm)

Mammalian

fog/water shrew 0.02 0.140 0.585 0.003 36.074 61.64

rice rat/star-nosed 

mole 0.1 0.107 0.484 0.011 31.659 65.43

small mink 0.5 0.079 0.293 0.048 33.929 115.67

large mink 1.8 0.062 0.229 0.168 26.510 115.67

small river otter 5.0 0.052 0.191 0.421 22.102 115.67

large river otter 15.0 0.042 0.157 1.133 27.371 174.19

Avian

sandpipers 0.0 0.228 1.034 0.004 67.9830 65.75

cranes 6.7 0.030 0.136 0.211 9.9245 73.03

rails 0.1 0.147 0.577 0.010 45.0152 77.96

herons 2.9 0.040 0.157 0.120 13.9553 88.66

small osprey 1.3 0.054 0.199 0.069 23.0669 115.67

white pelican 7.5 0.029 0.107 0.228 18.5864 174.19

Table 15. Calculation of toxicity values for mammals and birds consuming 

fish contaminated by Ethalfluralin.

Wildlife Species

Toxicity Values

Acute Chronic
129

Dose 

Based 

(mg/kgbw)

Dietary 

Based 

(mg/kg-diet)

Dose Based 

(mg/kg-bw)

Dietary 

Based 

(mg/kgdiet)

Mammalian

fog/water shrew 10499.51 N/A 128.09 1220

rice rat/star-nosed 

mole 7122.50 N/A 86.89 1220

small mink 4695.52 N/A 57.29 1220

large mink 3320.24 N/A 40.51 1220

small river otter 2571.84 N/A 31.38 1220

large river otter 1954.18 N/A 23.84 1220

Avian

sandpipers 1440.86 0.00 N/A 1000

cranes 3446.50 0.00 N/A 1000

rails 1738.73 0.00 N/A 1000

herons 3039.67 0.00 N/A 1000

small osprey 2679.19 0.00 N/A 1000

white pelican 3505.31 0.00 N/A 1000

Table 16. Calculation of RQ values for mammals and birds consuming fish 

contaminated by Ethalfluralin.

Wildlife Species

Acute Chronic

Dose 

Based

Dietary 

Based

Dose Based Dietary 

Based

Mammalian

fog/water shrew 0.003 N/A 0.282 0.051

rice rat/star-nosed 

mole 0.004 N/A 0.364 0.054

small mink 0.007 N/A 0.592 0.095

large mink 0.008 N/A 0.654 0.095

small river otter 0.009 N/A 0.704 0.095

large river otter 0.014 N/A 1.148 0.143
130

Avian

sandpipers 0.047 #DIV/0! N/A 0.066

cranes 0.003 #DIV/0! N/A 0.073

rails 0.026 #DIV/0! N/A 0.078

herons 0.005 #DIV/0! N/A 0.089

small osprey 0.009 #DIV/0! N/A 0.116

white pelican 0.005 #DIV/0! N/A 0.174

Appendix G. Risk Quotient Method

Risk characterization integrates the results of the exposure and ecotoxicity data to evaluate the 

likelihood of adverse ecological effects. The means of this integration is called the quotient 

method. Risk quotients (RQs) are calculated by dividing exposure estimates by acute and 

chronic ecotoxicity values. 

RQ = EXPOSURE/TOXICITY

RQs are then compared to OPP's levels of concern (LOCs). These LOCs are used by 

OPP to analyze potential risk to nontarget organisms and the need to consider regulatory action. 

The criteria indicate that a pesticide used as directed has the potential to cause adverse effects on 

nontarget organisms. LOCs currently address the following risk presumption categories: (1) 

acute risks - regulatory action may be warranted in addition to restricted use classification, (2) 

acute restricted use - the potential for acute risk is high, but may be mitigated through restricted 

use classification, (3) acute endangered species - endangered species may be adversely affected, 

and (4) chronic risk - the potential for chronic risk is high regulatory action may be warranted. 

Currently, EFED does not perform assessments for chronic risk to plants, acute or chronic risks 

to insects, or chronic risk from granular/bait formulations to birds or mammals.

The ecotoxicity test values (measurement endpoints) used in the acute and chronic risk 

quotients are derived from required studies. Examples of ecotoxicity values derived from shortterm laboratory studies that assess acute effects are: (1) LC50 (fish and birds), (2) LD50 (birds 

and mammals), (3) EC50 (aquatic plants and aquatic invertebrates) and (4) EC25 (terrestrial 

plants). Examples of toxicity test effect levels derived from the results of long-term laboratory 

studies that assess chronic effects are: (1) LOAEL or LOAEC (birds, fish, and aquatic 

invertebrates) and (2) NOAEL or NOAEC (birds, fish and aquatic invertebrates). For birds, 

mammals, fish and aquatic invertebrates the NOAEL or NOAEC generally is used as the 

ecotoxicity test value in assessing chronic effects, although other values may be used when 

justified. Risk presumptions and the corresponding RQs and LOCs, are tabulated below.
131

Table X. Risk presumptions for terrestrial animals based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Birds

Acute Risk EEC1/LC50 or LD50/ft2 or LD50/day3 0.5

Acute Restricted Use EEC/LC50 or LD50/ft2 or LD50/day (or LD50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC50 or LD50/ft2 or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Wild Mammals

Acute Risk EEC/LC50 or LD50/ft2 or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/ft2 or LD50/day (or LD50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC50 or LD50/ft2 or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

1

 abbreviation for Estimated Environmental Concentration (ppm) on avian/mammalian food items 2

 mg/ft2

3

 mg of toxicant consumed/day

 LD50 * wt. of bird

 LD50 * wt. of bird 

Table 2. Risk presumptions for aquatic animals based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Acute Risk EEC1/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Endangered Species EEC/LC50 or EC50 0.05

Chronic Risk EEC/NOAEC 1

1

 EEC = (ppm or ppb) in water

Table 3. Risk presumptions for plants based on risk quotients (RQ) and levels of concern (LOC).

Risk Presumption RQ LOC

Terrestrial and Semi-Aquatic Plants 

Acute Risk EEC1/EC25 1

Acute Endangered Species EEC/EC05 or NOAEC 1

Aquatic Plants

Acute Risk EEC2/EC50 1

Acute Endangered Species EEC/EC05 or NOAEC 1

1

 EEC = lbs ai/A 2

 EEC = (ppb/ppm) in water 
132

Appendix H. Environmental Degradates of Ethalfluralin

Proposed Pathway for Aerobic Degradation of Ethalfluralin (Source: MRID 41613918)

CHEMICAL NAMES OF DEGRADATES

ET-2E = N-Ethyl-2,6-dinitro-4- (trifluoromethyl)benzenamine

ET-4 = N2-Ethyl-N2-(2-methyl-2-propenyl)-3-nitro-5- (trifluoromethyl)-1,2-benzenediamine

ET-2M = N-(2-Methyl-2-propenyl)- 2,6-dinitro-4-(trifluoromethyl)benzenamine

ET-20 = 2,6-Dinitro-4-(trifluoromethyl)phenol

ET-15M = 2-Methyl-7-nitro-5-(trifluoromethyl)benzimidazole

ET-28E = 2,2’-Azoxybis(α,α,α-trifluoro-6-nitro-N-ethyl-p-toluldine)

ET-17E = 1 -Ethyl-7-nitro-5-(trifluoromethyl)benzimidazole

M1 = 2,3,4,5-Tetrahydro-5-ethyl-3-methylene-6-nitro-8-(trifluoromethyl)-1H-1,5-

benzodiazepine
133

Proposed Pathway for Anaerobic Degradation of Ethalfluralin (Source: MRID 41613919)

CHEMICAL NAMES OF DEGRADATES (not previously listed)

ET-3 = 2,6-Dinitro-4-(trifluoromethyl)benzenamine

ET-5E = N2-Ethyl-3-nitro-5-(trifluoromethyl)-1,2-benzenediamine

ET-7 = N2

-Ethyl-N2-(2-methyl-2-propenyl-5-(trifluoromethyl)-1,2,3-benzenetriamine

ET-13E = 1-Ethyl-2-(1-methylethenyl) -7-nitro-5-(trifluoromethyl)benzimidazole

M2 = 1-Ethyl-2-(1-methylethenyl)-5-(trifluoromethyl)-1H-benzimidazol-7-amine