UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C .. 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM DP Barcode D429863 

DATE: 

SUBJECT: 

TO: 

& 

FROM: 

THROUGH: 

February 24, 2016 

Ethalfluralin Drinking Water Assessment to Support Registration Review (DP 

Barcode D429863; PC Code 113101) 

Kelly Ballard, Chemical Review Manager 

Neil Anderson, Branch Chief 

Risk Management and Implementation Branch I 

Pesticide Re-evaluation Division 

Julie L. Van Alstine, Chemist 

Monica Hawkins, Ph.D., M.P.H., Environmental Health Scientist 

Donna Davis, Chief 

Risk Assessment Branch VI 

Health Effects Division (7509P) 

Michael R. Barrett, Senior Chemist 

Environmental Risk Branch V 

Environmental Fate and Effects Division (7507P) 

Environmental 

Mah T. Shamim, 

Risk 

Ph.D., 

Branch 

Chief 

V ;J~ Environmental Fate and Effects Division (7507P) 

Tier 2 Estimated Surface and Ground Drinking Water Concentrations (EDWCs) for ethalfluralin, 

a dinitroaniline herbicide, have been updated to support the registration review of ethalfluralin. 

The update is based upon new models not available for the proposed new uses and also reflects 

a request from the Health Effects Division to provide more refined estimates of exposure than 

previously available. There have been only minor changes in the registered uses since the last 

drinking water assessment (4/4/2013, DP Barcode D401526). Estimated drinking water 

concentrations are based on residues of ethalfluralin parent only (see Health Effects Division 

1 
2

Metabolism Committee (MARC) report, 5/25/1995). The maximum acute EDWC (based on 

surface water supply source drinking water) is 26.1 ppb of ethalfluralin, which is associated with 

the use on cucurbit crops; the chronic value is 0.57 ppb; and the cancer/chronic value is 0.36

ppb, both chronic values were associated with a scenario run to represent ethalfluralin use on 

soybeans. The maximum groundwater screening EDWC for acute exposure is 0.000437 ppb; 

and the chronic value is also 0.000437 ppb (see Table 1 for details).

Table 1. Maximum estimated drinking water concentrations for groundwater and surface 

water sources from the use of ethalfluralin.

DRINKING 

WATER 

SOURCE 

(MODEL 

USED) 

SCENARIO (USE) (rate modeled per 

year)

MAXIMUM ESTIMATED 

DRINKING WATER 

CONCENTRATION (EDWC) ( ppb)

Groundwater 

(PRZM-GW)

WI sand (1.7 lb a.i applied 1x per year) Acute 0.000437 1

WI sand (1.7 lb a.i.) Chronic 0.000437 1

Surface water 

(SWCC)

Acute: Cucurbits (FL Cucumber scenario; 

maximum single and seasonal application 

rate of 1.7 lb ai/A applied annually))

Chronic: Soybeans (MS corn scenario 

used as a surrogate for soybeans; 

maximum single and seasonal application 

rate of 1.31 lb ai/A applied annually)

Acute 26.1

Chronic (annual) 0.57

Chronic/Cancer (30+ 

years) 0.36

1 Based on a 100-year simulation with maximum rate applied every year. For the standard 30-year simulation the 

maximum acute concentration was 0.000437 ppb with the WI sand scenario. Since a “breakthrough” time was not 

established (the movement of low-level residues into the aquifer was too slow even with 100-year simulations) the 

chronic value was conservatively set to the same as the acute exposure value

Background and Use Summary

The Environmental Fate and Effects Division (EFED) has reviewed the current uses for the 

purposes of conducting an updated drinking water exposure assessment for the Registration 

Review of ethalfluralin. 

Chemistry and Fate

The chemical structure and name of ethalfluralin are provided in Table 2. For details on the 

environmental fate of ethalfluralin, including its complex degradation pathways to numerous 

minor degradation products in the environment, the reader is referred to the Preliminary 

Environmental Fate and Ecological Risk Assessment for the Registration Review of Ethalfluralin

(DP Barcode D429845). The moderate environmental persistence (generally from several 

weeks to a few months) and strong adsorption (resulting in dominant partitioning in soil and 

sediment to colloids and organic matter) are reflected in the exposure modeling input values 

for ethalfluralin, described later in this document.
3

Table 2. Chemical structure and identity of ethalfluralin.

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

Use Characterization

Labeling

Current labels Table 3) 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. Ethalfluralin maximum application 

rates and application methods are presented in 
4

Table 4. The maximum application rates are specified as a single or crop-cycle basis. 

Ethalfluralin is applied as a band/broadcast surface spray, chemigation applied through 

sprinklers, granular formulation with mechanical incorporation or incorporation through rainfall 

and/or sprinklers. Although not explicit on labels, it appears that applications are normally only 

made once per year / growing season (9/25/2015 correspondence from BEAD).

Table 3. Summary of ethalfluralin product labels registration numbers.

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

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)

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

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 
5

Table 4. Summary of ethalfluralin application rates and methods by crop site. 

Crop1 Application Timing

Single Application Rates 

(lbs a.i./A)2

Application Codes*

Soil Type Specific 

Rates

Label Information

Maximum Range

Variation max. rate 

with soil type, if 

applicable 3

Reg. No.

Alfalfa (ID, NV, WA & 

WY, MT, OR)

Pr-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 

Pre-plant (CU, PM), At 

seeding (All), Preemergence (All) & Post1.70 1.13 – 1.70 EC-1 F = 1.7, M = 1.5, C = 1.1

F = 1.2, M = 0.8, C = 0.6

34704-610

 1 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

NA = Not applicable (no variation of rates with soil texture classification specified).
6

Crop1 Application Timing Single Application Rates 

(lbs a.i./A)2 Application Codes*

Soil Type Specific 

Rates

Label Information

“SQ” summer/ 

winter)

emergence (PM, SQ) 0.40- 1.20

(w 

clomazone)

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

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
7

Crop1 Application Timing Single Application Rates 

(lbs a.i./A)2 Application Codes*

Soil Type Specific 

Rates

Label Information

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

Although not explicit on labels, it appears that applications are practically only made once per year / growing season (September 30, 2015 correspondence from 

BEAD).

* Application Codes:

EC: Applications with an emulsifiable concentrate 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

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.
8

Usage

In recent years, the use sites with a percent crop treated (estimated) of 10% or more have 

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

according to the screening-level use assessment (SLUA) provided by the Biological and 

Economic Analysis Division of the Office of Pesticide Programs, EPA (see Table 5).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 (the historical trends are shown in Figure 1 and Figure 

2). 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.

USGS methods and sources for estimating usage do vary from those in the Agency = discussed 

in the following paragraph.

According to Agency estimates, in recent years (2004-2013 aggregated data) the major use sites 

in terms of average % crop treated (estimated) of 10% or more are: cucumbers, pumpkins, 

squash, dry beans/peas, peanuts, watermelons, and sunflowers according to the screeninglevel use assessment (SLUA) provided by the Biological and Economic Analysis Division of the 

Office of Pesticide Programs, EPA (see Table 5). Usage on dry beans, peanuts, and sunflowers 

accounts for roughly 39%, 19%, and 26% respectively of the total pounds of ethalfluralin 

applied annually). Usage of ethalfluralin is estimated to occur on at most 30% of the total crop 

area dry beans, 30% of the crop area for peanuts, and 20% of the crop area for sunflowers. It is 

also important for cucumbers, applied to 50% of the crop area and for pumpkins, squash and 

water melons being applied from 20-25% of the crop area. The largest use in terms of the 

estimated annual acres treated has been dry beans/peas (ca. 600,000 acres annually). 

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

provided by the U.S. Geological Survey (see Figure 1 and Figure 2). 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 5. Screening Level Estimates of Agricultural Uses of Ethalfluralin for 2004-2013 (BEAD 

estimates, 6/11/2015).

Percent Crop Treated

Crops

Average Annual Lbs. 

A.I. Applied Average Annual Maximum

1 Alfalfa 9,000 <1 <2.5

2 Beans, Green+ 6,000 5 25

3 Cabbage+ <500 <1 <2.5
9

4 Canola 4,000 <2.5 <2.5

5 Cantaloupes 5,000 5 15

6 Cucumbers 50,000 50 65

7 Dry Beans/Peas 600,000 25 40

8 Peanuts 200,000 25 40

9 Peas, Green+ <500 <1 <2.5

10 Peppers+ <500 <1 <2.5

11 Potatoes 2,000 <1 <2.5

12 Pumpkins 20,000 30 40

13 Soybeans 40,000 <1 <2.5

14 Squash 10,000 30 35

15 Sunflowers 200,000 10 20

16 Watermelons 20,000 20 35

TOTAL (listed crops) ca. 1,168,000

Sorted Alphabetically

Reporting Years: 2004-2013

Compiled: June 11, 2015 

SLUA data sources include: 

USDA-NASS (United States Department of Agriculture's National Agricultural Statistics Service) 

Private Pesticide Market Research

+: Crop not known to be listed on active end use product registrations or as Section 18 emergency 

exemptions at the time of this report.

All numbers are rounded:

<500: less than 500 pounds of active ingredient; <2.5: less than 2.5 percent of crop is treated; <1: 

less than 1 percent of crop is treated. 

These results reflect amalgamated data developed by the Agency and are releasable to the public.
10

Figure 1. Ethalfluralin national usage estimates by crop and region as estimated by USGS for 

approximately 2002.

Caution: The pesticide use maps available from this site show the average annual pesticide use intensity expressed as average 

weight (in pounds) of a pesticide applied to each square mile of agricultural land in a county. The area of each map is based on 

state-level estimates of pesticide use rates for individual crops that were compiled by the CropLife Foundation, Crop Protection 

Research Institute during based on information collected during 1999 through 2004 and on 2002 Census of Agriculture county crop 

acreage. The maps do not represent a specific year, but rather show typical use patterns over the five year period 1999 through 

2004. Use intensity rates are expressed as the pounds applied per square mile of mapped agricultural land in a county. The area of 

mapped agricultural land for each county was obtained from an enhanced version of the 1992 USGS National Land Cover Data 

(NLCD). The key limitations of the data used to produce these maps include the following: (1) state use coefficients represent an 

average for the entire state and consequently do not reflect the local variability of pesticide management practices found within 

states and counties, (2) pesticide use estimates are not for a specific year, but represent typical use patterns for the five year period, 

(3) state pesticide use coefficients may not have been available for all states where a pesticide may have been applied to 

agricultural land, and therefore, are not displayed on the maps, (4) the county crop acreage is based on the 2002 Census of 

Agriculture and may not represent all crop acreage because of Census nondisclosure rules, and (5) agricultural land area used to 

calculate the pesticide use intensity and display the data was derived from 30-meter satellite remote sensing data that may over 

estimate or underestimate the actual agricultural land area. The maps are not intended for making local-scale estimates of pesticide 

use, such as estimates at the county level. Please refer to Method for Estimating Pesticide Use for a detailed discussion of how the 

pesticide use data were developed.

URL: http://water.usgs.gov/nawqa/pnsp/pubs/ofr00250/
11

Figure 2. Estimate agricultural use for ethalfluralin in the US 2012 map and 1992-2013 national 

summary (from USGS).
12

“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: 

Found at: 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

Exposure Assessment

Modeling was performed for parent ethalfluralin exposure alone which are the residues of 

concern for drinking water contributions to dietary exposure. Both surface water and 

groundwater exposure estimates were updated for the proposed new uses. These models are 

available on-line at: 

http://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/models-pesticide-riskassessment#aquatic

Aquatic Exposure Estimation Modeling Methods

Both groundwater (PRZM-GW model, version 1.07, 1/23/2014) and surface water (SWCC 

model, version 1.106, 5/22/2014) concentrations were estimated. For characterization, limited 

additional surface water exposure modeling was also done for characterization of the impact of 

volatilization as a dissipation factor with the Pesticides in Water Calculator (PWC, version 1.52, 

2/2/2016; not officially adopted for use by the Agency at the time of this assessment). The 

focus of this modeling summary is on the surface water modeling results which gave much 

higher EDWCs (estimated drinking water concentrations) than for groundwater (reflecting a 

very low leaching potential for the strongly adsorbed ethalfluralin molecule).

In this assessment, exposure estimates for each of the current crop uses presented 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 with very shallow 

incorporation (1 cm) is evaluated since this provides a conservative application scenario for 

runoff. However, estimated environmental concentrations in the water column for aquatic 

habitat are mostly dominated by spray drift4 and Ecological Exposure Assessments deposition 

directly in the receiving water body. The physicochemical plus fate parameters and the usespecific input parameters for the SWCC surface water modeling and PRZM-GW groundwater 

modeling are shown in Table 6 and Table 7, respectively. The EDWCs of ethalfluralin in surface 

 4 conservatively assumed to be 6.6% of the applied rate assuming a high boom ground application, see “Guidance on Use of Refined 

Spray Drift Deposition Data in Drinking Water” 
13

water are summarized in Table 8. A more detailed EEC summary and selected SWCC input / 

output files are provided in Appendix 1.

Table 6. Ethalfluralin physicochemical and fate property inputs for the SWCC and PRZM-GW

models.

PROPERTY VALUE DATA SOURCE COMMENTS

Molecular Weight 333.27 Product Chemistry

Hydrolysis Stable MRID # 000948-05

Water Solubility (pH 7, 

20oC)

0.3 mg/L Product Chemistry 

data

Water Solubility (pH 7, 20oC)

Vapor pressure (25 C)

(mm Hg)

8.2 x 10-5 Product Chemistry 

data Vapor pressure (25 C)

Diffusion in Air (cm2/d) 4300 PWC Guidance Used For PRZM-=GW 

Enthalpy (kcal/mol) 21.7 PWC Guidance Used For PRZM-=GW 

Henry’s Constant, 

unitless

1.64 x 10-1 Product Chemistry 

data

Used For PRZM-=GW 

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 soils5

Table 7. SWCC crop scenario and application related input parameter values for ethalfluralin 

aquatic exposure estimation,

Use Represented

Scenario IDs Application dates 

(for separate 

# of applications / 

year

Application rate 

(kg ai /ha)

 5 European Union dossier Koc range 3967-8083 mL/g. See: http://sitem.herts.ac.uk/aeru/footprint/en/Reports/271.htm .
14

simulations

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

11 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

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”.

For all model runs a Percent Crop Area (PCA) factor of 0.91 was used assuming potential uses 

on all agricultural land. For details on this calculation please see: 

https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/supersededdevelopment-and-use-percent-cropped-area .

.
15

Surface Water Modeling Results

The maximum aquatic EECs by crop based on the SWCC farm pond scenario are summarized in 

Table 8 (representing multiple scenarios and application dates tested, full results are provided 

in Appendix 1).

Table 8. SWCC estimated upper bound drinking water concentrations of ethalfluralin in the 

surface water column by crop use site.

Crop Represented

(Scenario ID)

Applicat. 

Date Peak Chronic (annual)

Cancer

(30+ yrs.)

(Maximum EDWCs by crop, ppb6)

Soybeans Oct. 10

13.74 0.57 0.36 (MS Corn)

Sunflower+ Jun. 10

14.92 0.44 0.29 (KS Corn) 

Cucurbits Oct. 30

26.12 1 0.55 1 --- (FL Cucumber)

Cucurbits

(FL Cucumber) Oct. 15 0.29 1

Peanuts May 1 4.68 0.18 0.13 (NC Peanut)

Dry Beans May 15 4.41 0.21 0.15 (MI Beans)

Potatoes May 10 2.67 0.11 0.08 (ID New Potato)

Alfalfa and Clover Jan. 10

4.3 0.21 0.15

(CA Alfalfa OP)

Only the highest EDWCs are presented from multiple runs with different application dates 

for a particular crop. More detailed results are available in the Appendix

Additional use sites represented by the 

Sunflower - Conservative for other oilseed crops.

Dry Beans - Conservative for lentils.

Alfalfa, Clover - Conservative for dill.

1 Corresponding estimates if application is truly uniformly incorporated to a 4 cm depth 

are: 17.8 ppb (peak) and 0.38 ppb (annual) using an annual application of October 30; the 

 6 Highest EDWCs for each exposure duration are in bold text.
16

chronic cancer value is 0.21 ppb. (See appendix for a model input / output summary.)

Characterization of Volatilization as a Dissipation Mechanism

Additional surface water exposure modeling was done with the PWC that incorporates a peerapproved volatilization routine7. However, this information is for characterization, should 

future refinements be needed in the drinking water exposure modeling. The following 

scenarios were run with PWC in a mode representing the maximum allowed rates on the label 

for application to soybeans:

ILCornSTD 

INCornStd 

KSCornStd 

MNCornStd 

MScornSTD 

MSsoybeanSTD 

NCcornESTD 

The results were that acute exposure, chronic (annual), and long-term chronic (for cancer risk 

estimation) exposure estimates were reduced by 8, 10, and 13% respectively by invoking the 

volatilization routine. The PWC was determined to give the same results within 1 or 2% as the 

same scenario runs in the SWCC model when the volatilization routine in PWC was not invoked. 

Groundwater Modeling Results 

The EDWCs for groundwater (calculated with the PRZM-GW model) are much lower than for 

surface water and have not been used for the dietary exposure evaluation for ethalfluralin by 

the Health Effects Division. These predicted concentrations are mostly, if not entirely below 

current analytical method minimum detection limits and are more than an order of magnitude 

lower than the EDWCs for surface-water based drinking water sources.

Table 9. PRZM-GW estimated upper bound drinking water concentrations of ethalfluralin in 

groundwater at the highest application rate for current crop uses (ppb).

Scenario ID Peak(ppb)

PBT 

Avg(ppb)

SIM 

Avg Throughputs

90-day 

Avg

NCCOASTAL_STD_extend.SCN 0.014700 NA 0.01 0.92 0.014700

 7 Guidance for Using the Volatilization Algorithm in the Pesticide in Water Calculator and Water Exposure Models. Environmental

Fate and Effects Division, Office of Pesticide Programs, EPA; December 8, 2015.
17

FLCITRUS_STD_extend.SCN 0.012900 NA 0.01 0.90 0.012900

FLPOTATO_STD_extend.SCN 0.012900 NA 0.01 0.90 0.012900

DELMARVA_STD_extend.SCN 0.003880 NA 0.00 0.74 0.003850

WISANDS_STD_extend.SCN 0.002020 NA 0.00 0.65 0.002020

GACOASTAL_STD_extend.SCN 0.000004 NA 0.00 0.54 0.000004

All scenarios were modified from the original data set with 30 years of weather data to a 100-

year data using the weather data extender supplied with the model. Ethalfluralin was assumed 

to be applied at the maximum use rate for every year of the simulation. The six standard 

scenarios run are described here: https://www.epa.gov/pesticide-science-and-assessingpesticide-risks/przm-gw-version-107-guidance-using-przm-gw-drinking

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

usage pattern associated with relatively high levels in water that might be used by drinking 

water supplies. There is a lack of monitoring data for ethalfluralin residues 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 (WQP), a 

cooperative service also sponsored by the United States Geological Survey (USGS), the 

Environmental Protection Agency (EPA), was conducted on 1/21/2016. It serves data collected 

by over 400 state, federal, tribal, and local agencies and includes 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. 

USDA Pesticide Data Program
18

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 and found to contain no detectable residues of ethalfluralin. 

NAWQA Surface Water Monitoring

The USGS NAWQA8 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.). These data include monitoring of drinking, other use, and observation wells. 

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 States9. 

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 in North Dakota

There were 5 or less detections in all other states in which monitoring data were collected 

from.

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

 8 http://infotrek.er.usgs.gov/nawqa_queries/swmaster/index.jsp (visited December 23, 2010) 9 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. 
19

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.

When further reviewing the monitoring data, it is important to note that ethalfluralin has been 

a relatively minor use chemical over the last 20 years when virtually all of the available 

monitoring data have been collected. For example, annual usage in the early 1990s was 

estimated to be about 2.3 to 4.2 million pounds – refer to the “Reregistration Eligibility Decision 

(RED): Ethalfluralin” published by OPP in March 1995 for details). In the RED the largest usage 

site was estimated to be soybeans (3.1 to 5.7 million acres treated but only 2 to 5% of the total 

US soybean acreage). More recently, in the early 2000s (when NAWQA sampling continued) the 

annual usage has been estimated to be 1.9 million pounds with the largest use on sunflower 

seed crops. These national usage levels are low enough that it is likely that most monitoring 

studies will primarily sample in areas of little or no ethalfluralin usage unless they are 

specifically targeted to ethalfluralin usage areas. 

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 Loads (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

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

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

The Agency invites submission of water quality data for this pesticide. To the extent possible, 

data should conform to the quality standards in Appendix A of the OPP Standard Operating 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPPs 

Registration Review Risk Assessment and Management Process (see: 

http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf), in order to 

ensure they can be used quantitatively or qualitatively in pesticide risk assessments 

Exposure Summary

Ethalfluralin has an environmental fate profile which is generally associated with a higher 

potential for offsite transport primarily via sediment but including to some extent in dissolved 

phase, spray drift (if the application method does not prevent it), and to a very limited extent 

by leaching. The exposure modeling results appear to confirm this hypothesis with much higher 

concentrations predicted in surface water than groundwater supplies and with significant 

transport to drinking water sources via spray drift when incomplete wetting in or physical 
20

incorporation was assumed in the exposure modeling (results are summarized in Table 1; only 

dissolved concentrations were predicted since ethalfluralin bond to sediment or organic carbon 

is not relevant to drinking water exposure). 
21

APPENDIX 1: Drinking Water Exposure Modeling Input and Output

A summary of the estimated drinking water exposure concentrations is provided in Table 10. 

Example model input and output files follow.

Table 10. Estimated drinking water concentrations (μg/L) of parent ethalfluralin for various 

durations of exposure using scenarios to represent current crop uses.

Scenario ID Crops Represented

App. 

Date

App. 

Rate 

lb/A

PCA 

Factor Acute

Chronic

-yearly

Lifetim

e

ILCornSTD Soybean 10-Jun 1.31 0.91 4.88 0.20 0.14

KSCornStd Soybean 10-Jun 1.31 0.91 11.56 0.34 0.22

MScornSTD Soybean 10-Jun 1.31 0.91 9.28 0.42 0.20

MSsoybeanST

D Soybean 10-Jun 1.31 0.91 8.86 0.36 0.17

NCcornESTD Soybean 10-Jun 1.31 0.91 9.10 0.28 0.19

OHCornSTD Soybean 10-Jun 1.31 0.91 4.65 0.22 0.15

PAcornSTD Soybean 10-Jun 1.31 0.91 3.19 0.15 0.12

ILCornSTD Soybean 25-Jun 1.31 0.91 4.11 0.10 0.08

KSCornStd Soybean 25-Jun 1.31 0.91 4.15 0.14 0.10

MScornSTD Soybean 25-Jun 1.31 0.91 4.18 0.18 0.11

MSsoybeanST

D Soybean 25-Jun 1.31 0.91 4.10 0.15 0.10

NCcornESTD Soybean 25-Jun 1.31 0.91 4.19 0.12 0.10

OHCornSTD Soybean 25-Jun 1.31 0.91 4.76 0.11 0.09

PAcornSTD Soybean 25-Jun 1.31 0.91 4.11 0.09 0.08

ILCornSTD Soybean 10-Oct 1.31 0.91 3.79 0.22 0.15

KSCornStd Soybean 10-Oct 1.31 0.91 8.99 0.27 0.18

MScornSTD Soybean 10-Oct 1.31 0.91 13.74 0.55 0.34

MSsoybeanST

D Soybean 10-Oct 1.31 0.91 10.65 0.46 0.28
22

NCcornESTD Soybean 10-Oct 1.31 0.91 7.96 0.30 0.20

OHCornSTD Soybean 10-Oct 1.31 0.91 4.22 0.29 0.19

PAcornSTD Soybean 10-Oct 1.31 0.91 3.25 0.17 0.14

ILCornSTD Soybean 25-Oct 1.31 0.91 4.25 0.23 0.16

KSCornStd Soybean 25-Oct 1.31 0.91 6.76 0.28 0.17

MScornSTD Soybean 25-Oct 1.31 0.91 10.19 0.57 0.36

MSsoybeanST

D Soybean 25-Oct 1.31 0.91 9.05 0.47 0.30

NCcornESTD Soybean 25-Oct 1.31 0.91 11.74 0.35 0.21

OHCornSTD Soybean 25-Oct 1.31 0.91 5.61 0.34 0.22

PAcornSTD Soybean 25-Oct 1.31 0.91 3.63 0.18 0.14

ND Canola Sunflower 15-May 1.70 0.91 4.27 0.14 0.10

ND Canola Sunflower 10-Jun 1.70 0.91 4.15 0.16 0.11

ND Canola Sunflower 10-Oct 1.70 0.91 4.14 0.12 0.10

ND Canola Sunflower 25-Oct 1.70 0.91 4.14 0.13 0.12

KS corn Sunflower 15-May 1.70 0.91 9.10 0.41 0.27

KS corn Sunflower 10-Jun 1.70 0.91 14.92 0.44 0.29

KS corn Sunflower 10-Oct 1.70 0.91 11.65 0.35 0.23

KS corn Sunflower 25-Oct 1.70 0.91 8.76 0.36 0.22

FL cucumber Cucurbits 15-Oct 1.70 0.91 18.56 0.53 0.29

FL cucumber Cucurbits 30-Oct 1.70 0.91 26.12 0.55 0.28

NC Peanut Peanut 1-May 1.15 0.91 4.68 0.18 0.13

MI Bean Dry beans 15-May 1.69 0.91 4.41 0.21 0.15

ID Npotato Potatoes 10-May 1.03 0.91 2.67 0.11 0.08

CA Alfalfa w 

Irrig Alfalfa, Clover 10-Jan 1.69 0.91 4.30 0.21 0.15

Maximum 26.12 0.57 0.36

Minimum 2.67 0.09 0.08
23

Crops 

Represented

App. Rate 

lb/A

PCA 

Factor Acute

Chronicyearly Lifetime

Soybean Max 1.31 0.91 13.74 0.57 0.36

Sunflower Max 1.70 0.91 14.92 0.44 0.29

Cucurbits Max 1.70 0.91 26.12 0.55 0.29

Peanut Max 1.15 0.91 4.68 0.18 0.13

Dry beans Max 1.69 0.91 4.41 0.21 0.15

Potatoes Max 1.03 0.91 2.67 0.11 0.08

Alfalfa, Clover 

Max 1.69 0.91 4.3 0.21 0.15

Grand Max 26.12 0.57 0.36

Table 11. SWCC application related input parameter summary – representative crops.

MODEL 

PARAMETER

VALUE DATA SOURCE COMMENTS

Application Rate 1.905 kg ai/ha

1.7 lb ai/A

Labels Highest rate on label for oilseed 

crops (corresponds to the maximum 

rate for applications in sunflowers / 

20B crop group to control 

groundcherry and nightshade in fine 

textured soils.) Implied is that only 1 

application should be made per 

season / year.

1.905 kg ai/ha

1.70 lb ai/A

Representing cucumber and other 

cucurbits. 

1.289 kg ai/ha

1.15 lb ai/A Representing peanuts

1.894 kg ai/ha

1.69 lb ai/A Representing dry beans

1.152 kg ai/ha

1.03 lb ai/A Representing potatoes.

1.894 kg ai/ha

1.69 lb ai/A Representing alfalfa and clover

Chemical 

Application 

method (CAM) 

Specified depth Label 

Soil incorporation of the applied 

pesticide is completely at a specified 

depth. 
24

Depth of 

Incorporation

(DEPI)

1 cm See notes. Ethalfluralin applications are often 

(typically?) physically incorporated 

but wetting in via rainfall or irrigation 

is an option. 1 cm is a conservative 

assumption for when the depth of 

incorp. Does\ not reach target levels.

Spray Drift 

Fraction

0.064 Label 

Per Input Guidance (default 

assumption for ground applications; 

note that no aerial uses are specified 

on the labels)

Input Parameter guidance citation: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

Surface Water Simulations: Sample Model Input and Output

Variable Volume Water Model, SWCC Compatible Version

*******************************************

Performed on: 1/19/2016 at 18:15

Peak 1-in-10 = 12.4 ppb

Chronic 1-in-10 = 0.244 ppb

Simulation Avg = 0.147 ppb

4-day avg 1-in-10 = 8.29 ppb

21-day avg 1-in-10 = 3.50 ppb

60-day avg 1-in-10 = 1.35 ppb

90-day avg 1-in-10 = 1.01 ppb

Benthic Pore Water Peak 1-in-10 = 0.484 ppb

Benthic Pore Water 21-day avg 1-in-10 = 0.329 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
25

 1 5.85E+00 3.42E+00 1.12E+00 4.00E-01 2.67E-01 6.58E-02 1.71E-01 1.10E-01

 2 5.85E+00 3.82E+00 1.22E+00 4.50E-01 3.03E-01 8.99E-02 1.92E-01 1.25E-01

 3 5.85E+00 3.90E+00 1.42E+00 5.47E-01 3.90E-01 1.09E-01 2.00E-01 1.44E-01

 4 7.94E+00 6.07E+00 2.10E+00 1.10E+00 7.34E-01 2.20E-01 3.31E-01 2.19E-01

 5 1.51E+01 9.15E+00 2.80E+00 1.04E+00 7.38E-01 1.83E-01 4.81E-01 2.80E-01

 6 5.85E+00 3.97E+00 1.23E+00 4.42E-01 7.81E-01 1.20E-01 2.02E-01 1.26E-01

 7 5.85E+00 3.44E+00 1.05E+00 3.81E-01 3.12E-01 8.67E-02 1.75E-01 1.08E-01

 8 5.85E+00 3.82E+00 1.32E+00 4.86E-01 3.25E-01 1.01E-01 1.93E-01 1.38E-01

 9 5.91E+00 3.32E+00 1.10E+00 4.78E-01 3.84E-01 1.12E-01 1.64E-01 1.09E-01

10 5.85E+00 3.91E+00 1.31E+00 4.70E-01 4.01E-01 1.30E-01 1.97E-01 1.32E-01

11 1.25E+01 8.34E+00 3.52E+00 1.27E+00 8.45E-01 2.19E-01 5.40E-01 3.35E-01

12 1.18E+01 7.82E+00 3.39E+00 1.28E+00 8.61E-01 2.36E-01 4.39E-01 2.85E-01

13 5.85E+00 3.90E+00 1.33E+00 1.05E+00 8.77E-01 9.81E-02 1.98E-01 1.29E-01

14 5.85E+00 3.37E+00 1.19E+00 5.72E-01 5.09E-01 1.50E-01 1.64E-01 1.08E-01

15 5.85E+00 3.12E+00 9.55E-01 3.49E-01 3.84E-01 6.31E-02 1.46E-01 9.01E-02

16 5.85E+00 3.77E+00 1.77E+00 6.57E-01 4.40E-01 1.31E-01 2.70E-01 1.83E-01

17 5.85E+00 3.92E+00 1.40E+00 9.73E-01 6.53E-01 1.91E-01 2.06E-01 1.43E-01

18 8.41E+00 6.43E+00 3.52E+00 1.35E+00 9.11E-01 2.45E-01 4.85E-01 3.33E-01

19 5.85E+00 2.94E+00 8.86E-01 1.09E+00 9.22E-01 8.02E-02 1.38E-01 8.56E-02

20 5.85E+00 3.87E+00 1.24E+00 5.19E-01 3.46E-01 1.18E-01 1.87E-01 1.18E-01

21 7.25E+00 4.58E+00 2.01E+00 7.37E-01 5.12E-01 1.42E-01 2.82E-01 1.90E-01

22 1.30E+01 8.90E+00 4.34E+00 1.61E+00 1.08E+00 3.15E-01 5.31E-01 4.03E-01

23 5.85E+00 3.60E+00 1.69E+00 1.11E+00 1.20E+00 1.77E-01 2.17E-01 1.65E-01

24 1.21E+01 7.90E+00 2.45E+00 1.51E+00 1.00E+00 2.81E-01 4.43E-01 2.94E-01

25 5.85E+00 3.92E+00 1.30E+00 1.28E+00 1.01E+00 9.01E-02 1.88E-01 1.20E-01

26 5.85E+00 4.41E+00 1.63E+00 9.54E-01 6.60E-01 2.17E-01 2.20E-01 1.46E-01

27 9.24E+00 5.63E+00 2.26E+00 8.47E-01 6.95E-01 1.58E-01 3.58E-01 2.20E-01

28 5.85E+00 4.37E+00 1.56E+00 6.38E-01 5.86E-01 1.14E-01 2.46E-01 1.55E-01

29 5.85E+00 3.95E+00 1.29E+00 5.03E-01 3.76E-01 9.42E-02 2.03E-01 1.31E-01

30 5.85E+00 3.54E+00 1.01E+00 3.61E-01 3.51E-01 7.30E-02 1.64E-01 9.56E-02

******************************************************************************

**********************

Effective compartment halflives averaged over simulation duration:

zero washout 0

water col metab halflife (days) = 104.339052092883 

zero hydrolysis 0

photolysis halflife (days) = 22.5855161524610 

volatile halflife (days) = 6.25742522473543 

total water col halflife (days) = 4.68010450792052 

zero burial 0

benthic metab halflife (days) = 5.10938657155869 

zero benthic hydrolysis 0
26

total benthic halflife (days) = 5.10938657155869 

***********************************************************************

Fractional Contribution of Transport Processes to Waterbody & Total Mass (kg):

Due to Runoff = 0.5577 4.468 

Due to Erosion = 0.0000 0.000 

Due to Drift = 0.4423 3.543 

***********************************************************************

Flow in/out Characteristics of Waterbody:

Average Daily Runoff Into Waterbody (m3/s) = 1.853148511537314E-003

Baseflow Into Waterbody (m3/s) = 0.000000000000000E+000

Average Daily Flow Out of Waterbody (m3/s) = 1.853148511537358E-003

***********************************************************************

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

 0.5000E-02 = chlorophyll

 0.4000E-01 = OC frcation in water column SS
27

 5.000 = DOC in water column

 0.4000 = biomass in water column

FRACTION AREA CROPPED = 1.00000000000000 

Input File Name: SWCC_ethalfl-RR2015_FLcucu_Reserv+Pond_Oct30 app (rep 

Cucurb)67dASMH2O134d.SWI

Output File Name: 

SWCC_ethalfl-RR2015_FLcucu_Reserv+Pond_Oct30 app (rep 

Cucurb)48.5dASMH2O97d_FLcucumberSTD_Pond_Parent.txt

Description: Using the Florida Cucumber scenario to represent uses on cucurbits.

Description: Used as a batch processing for all six standard scenarios with 100-years of weather data. 

Copy of Output File with input summary:

Variable Volume Water Model, SWCC Compatible Version

*******************************************

Performed on: 1/19/2016 at 18:15

Peak 1-in-10 = 12.4 ppb

Chronic 1-in-10 = 0.244 ppb

Simulation Avg = 0.147 ppb

4-day avg 1-in-10 = 8.29 ppb

21-day avg 1-in-10 = 3.50 ppb

60-day avg 1-in-10 = 1.35 ppb

90-day avg 1-in-10 = 1.01 ppb

Benthic Pore Water Peak 1-in-10 = 0.484 ppb

Benthic Pore Water 21-day avg 1-in-10 = 0.329 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 3.42E+00 1.12E+00 4.00E-01 2.67E-01 6.58E-02 1.71E-01 1.10E-01

 2 5.85E+00 3.82E+00 1.22E+00 4.50E-01 3.03E-01 8.99E-02 1.92E-01 1.25E-01

 3 5.85E+00 3.90E+00 1.42E+00 5.47E-01 3.90E-01 1.09E-01 2.00E-01 1.44E-01

 4 7.94E+00 6.07E+00 2.10E+00 1.10E+00 7.34E-01 2.20E-01 3.31E-01 2.19E-01

 5 1.51E+01 9.15E+00 2.80E+00 1.04E+00 7.38E-01 1.83E-01 4.81E-01 2.80E-01

 6 5.85E+00 3.97E+00 1.23E+00 4.42E-01 7.81E-01 1.20E-01 2.02E-01 1.26E-01

 7 5.85E+00 3.44E+00 1.05E+00 3.81E-01 3.12E-01 8.67E-02 1.75E-01 1.08E-01

 8 5.85E+00 3.82E+00 1.32E+00 4.86E-01 3.25E-01 1.01E-01 1.93E-01 1.38E-01

 9 5.91E+00 3.32E+00 1.10E+00 4.78E-01 3.84E-01 1.12E-01 1.64E-01 1.09E-01

10 5.85E+00 3.91E+00 1.31E+00 4.70E-01 4.01E-01 1.30E-01 1.97E-01 1.32E-01

11 1.25E+01 8.34E+00 3.52E+00 1.27E+00 8.45E-01 2.19E-01 5.40E-01 3.35E-01
28

12 1.18E+01 7.82E+00 3.39E+00 1.28E+00 8.61E-01 2.36E-01 4.39E-01 2.85E-01

13 5.85E+00 3.90E+00 1.33E+00 1.05E+00 8.77E-01 9.81E-02 1.98E-01 1.29E-01

14 5.85E+00 3.37E+00 1.19E+00 5.72E-01 5.09E-01 1.50E-01 1.64E-01 1.08E-01

15 5.85E+00 3.12E+00 9.55E-01 3.49E-01 3.84E-01 6.31E-02 1.46E-01 9.01E-02

16 5.85E+00 3.77E+00 1.77E+00 6.57E-01 4.40E-01 1.31E-01 2.70E-01 1.83E-01

17 5.85E+00 3.92E+00 1.40E+00 9.73E-01 6.53E-01 1.91E-01 2.06E-01 1.43E-01

18 8.41E+00 6.43E+00 3.52E+00 1.35E+00 9.11E-01 2.45E-01 4.85E-01 3.33E-01

19 5.85E+00 2.94E+00 8.86E-01 1.09E+00 9.22E-01 8.02E-02 1.38E-01 8.56E-02

20 5.85E+00 3.87E+00 1.24E+00 5.19E-01 3.46E-01 1.18E-01 1.87E-01 1.18E-01

21 7.25E+00 4.58E+00 2.01E+00 7.37E-01 5.12E-01 1.42E-01 2.82E-01 1.90E-01

22 1.30E+01 8.90E+00 4.34E+00 1.61E+00 1.08E+00 3.15E-01 5.31E-01 4.03E-01

23 5.85E+00 3.60E+00 1.69E+00 1.11E+00 1.20E+00 1.77E-01 2.17E-01 1.65E-01

24 1.21E+01 7.90E+00 2.45E+00 1.51E+00 1.00E+00 2.81E-01 4.43E-01 2.94E-01

25 5.85E+00 3.92E+00 1.30E+00 1.28E+00 1.01E+00 9.01E-02 1.88E-01 1.20E-01

26 5.85E+00 4.41E+00 1.63E+00 9.54E-01 6.60E-01 2.17E-01 2.20E-01 1.46E-01

27 9.24E+00 5.63E+00 2.26E+00 8.47E-01 6.95E-01 1.58E-01 3.58E-01 2.20E-01

28 5.85E+00 4.37E+00 1.56E+00 6.38E-01 5.86E-01 1.14E-01 2.46E-01 1.55E-01

29 5.85E+00 3.95E+00 1.29E+00 5.03E-01 3.76E-01 9.42E-02 2.03E-01 1.31E-01

30 5.85E+00 3.54E+00 1.01E+00 3.61E-01 3.51E-01 7.30E-02 1.64E-01 9.56E-02

*************************************************************************************

***************

Effective compartment halflives averaged over simulation duration:

zero washout 0

water col metab halflife (days) = 104.339052092883 

zero hydrolysis 0

photolysis halflife (days) = 22.5855161524610 

volatile halflife (days) = 6.25742522473543 

total water col halflife (days) = 4.68010450792052 

zero burial 0

benthic metab halflife (days) = 5.10938657155869 

zero benthic hydrolysis 0

total benthic halflife (days) = 5.10938657155869 

***********************************************************************

Fractional Contribution of Transport Processes to Waterbody & Total Mass (kg):

Due to Runoff = 0.5577 4.468 

Due to Erosion = 0.0000 0.000 

Due to Drift = 0.4423 3.543 

***********************************************************************

Flow in/out Characteristics of Waterbody:

Average Daily Runoff Into Waterbody (m3/s) = 1.853148511537314E-003

Baseflow Into Waterbody (m3/s) = 0.000000000000000E+000

Average Daily Flow Out of Waterbody (m3/s) = 1.853148511537358E-003

***********************************************************************

Inputs:

 3957. = oc partitioning coefficient
29

 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

 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 
30

SWCC KS Corn Scenario (for assessment of soybean use)Output Summary
31

SWCC KS Corn Scenario (for assessment of soybean use) Ethalfluralin Chemical-Related Input Summary

SWCC KS Corn Scenario (for assessment of soybean use) Ethalfluralin Application-Related Input 

Summary
32

PWC 1.52 Sample Model Input / Output

Input (*.SWI) File for Batch run of 7 Scenarios to Represent the Soybean Use Site (with 

Volatilization Routine Invoked):

Pesticide Water Calculator (PWC), Version 1.52

Ethalfluralin 48asm no vol 4cm-ap

1

True

3957,,,

97,,,

25,,,

4.75,,,

25,,,

0.263,,,

40,,,

0,,,

48,,,

25,

0,,,

333.27,,,

8.2E-5,,,

0.3,,,

0,0,

0,0,

0,0,

0,0,

0,0,

0,0,

0.0,,,

0.0049,,,

0.0,,,

2

1

30,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

10,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

1.905,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

False

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

3,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
33

.99,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.062,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.99,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

.0661,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

4,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

True

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

,

,

,

FLcucumberSTD

C:\Models\Inputs\Metfiles\W12844.dvf

True,True,False,False,False,False, False

False,30,1,

False

10000

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

16

10

5

12

10

12
34

50,30

80

0.15

1

0.78

0

32.5

0

,False,

0.03

0.2

1

4

1

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

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,.

285,.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,.

011,.011,.011,.011,.011,.011,.011,.011,,,,,,,,,,,,,,,,,,,,,,,,,,

2.0,1.55,0.266,

0.1,0,1.0,

False

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

5.0
35

4

Summary of Reservoir Modeling of Ethalfluralin Modeling – PA Corn scenario

(Representing Soybean Use, Oct. 10 Annual Applications Placed at 1 cm depth 

Estimated Environmental Concentrations for Ethalfluralin are presented in Table 1 for the 

USEPA standard reservoir with the PAcornSTD 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 0.83% 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 runoff 

(75.8% of the total transport) followed by spray drift (24.2%).

In the water body, pesticide dissipates with an effective water column half-life of 24.1 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 photolysis (effective average half-life = 42.3 days) followed by 

washout (79.7 days) and metabolism (187 days).

In the benthic region, pesticide dissipates (9.2 days). The main source of dissipation in the 

benthic region is metabolism (effective average half-life = 9.2 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.

Peak (1-in-10 yr) 17.4

4-day Avg (1-in-10 yr) 14.5

21-day Avg (1-in-10 yr) 8.89

60-day Avg (1-in-10 yr) 4.37

365-day Avg (1-in-10 yr) 0.882

Entire Simulation Mean 0.562

Table 2. Summary of Model Inputs for Ethalfluralin.

Scenario PAcornSTD

Cropped Area Fraction 1.0

Koc (ml/g) 3957

Water Half-Life (days) @ 25 °C 97

Benthic Half-Life (days) @ 25 °C 4.75
36

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 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.

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift

10/10 Placed at a 

depth of 1 cm

1.47 .99 .0661

Figure 1. Yearly Peak Concentrations

Summary of Reservoir Modeling of Ethalfluralin Modeling – FL Cucumber 

scenario, Oct. 30 Annual Applications Uniformly incorp. to 4 cm
37

Estimated Environmental Concentrations for Ethalfluralin are presented in Table 1 for the 

USEPA standard reservoir 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 0.74% 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 runoff 

( 68% of the total transport), followed by spray drift (27.2%) and erosion (4.87%).

In the water body, pesticide dissipates with an effective water column half-life of 5.4 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 = 8.6 days) followed by photolysis 

(30.9 days), washout (36.1 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.

Peak (1-in-10 yr) 19.5

4-day Avg (1-in-10 yr) 13.8

21-day Avg (1-in-10 yr) 5.77

60-day Avg (1-in-10 yr) 2.46

365-day Avg (1-in-10 yr) 0.423

Entire Simulation Mean 0.225

Table 2. Summary of Model Inputs for Ethalfluralin.

Scenario FLcucumberSTD

Cropped Area Fraction 1.0

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
38

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.

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift

10/30 Incorporated to 

4 cm

1.905 .99 .0661

Figure 1. Yearly Peak Concentrations
39

Groundwater Simulations: Sample Model Input and Output

Table 12. PRZM-GW Groundwater simulation results for ethalfluralin uses (Tier 1 5 standard 

scenarios).

Florida Central Ridge Scenario
40

Florida Jacksonville Area Scenario
41

Georgia Coastal Plain Scenario
42

North Carolina Coastal Plain Scenario
43

Wisconsin Central Sands Scenario

Input File Name: PzGW_Ethalfl_48ASM-97AerAq_vol_Batch100yr.PGI

Description: Used as a batch processing for all six standard scenarios with 100-years of weather data. 

Description: Used as a batch processing for all six standard scenarios with 100-years of weather data. 

Copy of Input File:

Ethalfluralin (w/ Volat)

0

48.5

True

3957

1

1

,,,,,,,,,,,,,,,,,,,,,,,,,
44

,,,,,,,,,,,,,,,,,,,,,,,,,

1.91,,,,,,,,,,,,,,,,,,,,,,,,,

4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

-1,,,,,,,,,,,,,,,,,,,,,,,,,

False

1

last

4300,1.64E-1,21.7

7,,,,,,,,,,,,,,,,,,,,,,,,,

future expansion

future expansion

future expansion

future expansion

future expansion

future expansion

future expansion

Wisconsin Corn - WI Central Sands

C:\models\Inputs\Metfiles\w14920Extended.dvf

0.76

0.36

18

90,100

100

0.25

01

05

21

07

20

10

1

2

0.1

0.9

4.0

9

1.63,1.63,1.68,1.68,1.59,1.59,1.59,1.59

0.24,0.24,0.22,0.22,0.23,0.23,0.23

0.034,0.034,0.025,0.025,0.016,0.016,0.016

0.46,0.46,0.14,0.09,0.09,0.08,0.07,0.07

True

95,95,96,96,97,97,97,97

2.3,2.3,2.5,2.5,1.7,1.7,1.7,1.7

5.6

0.2

50

1