UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHIN G TON D

. C

.. 20 4 60

OFF I CE OF

CHE M IC AL S A FETY A N D

POLLUTIO N PREVENTION



### MEMORANDUM DP Barcode D429863

DATE:

S UBJECT :

TO :

&

FROM:

THROUGH : February 24, 20 16

Et h a lflur a lin D rinking Water As sess ment to Support Registration Review (D P
Barcode D429863; PC Code 113101 )

Kelly Ballard

, Chemical Review Manager
Neil Anderson, Branch Chief
Risk Management and Impl ementation Branch I
Pesticide Re

- evaluation Division

Julie L. Van A l stine, Chemist
Monica Hawkins

, Ph.D., M.P.H

., Environmen tal Health Scientist Donna Davis, Chief
Risk Assessment Branch VI
Health Effects Division (7509P)

Mich ael R. Barrett, Senior C hemi st Environm e ntal Risk Branch V
Environmental Fate and Effect s Division (7507P)

# ;J~ Mah T. Shamim, Ph.D., Chi ef
Environmental Risk Branch V
Envi r onmental Fate and Effects D i vi s ion (7507P)

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

a dinitroaniline herbicide

, have been upd ated to support the registration review of ethalflura l in

. The update is based upon new models not available for the proposed new uses and also refle cts

a request from the Hea lth Effects Division to provide more refined est imat es of exposure than previously available

. There have been only m i nor changes in the regi ste r ed u s es s ince the last drinking water as sess ment (4/4/2013, DP Barcode D401526). Estimated drinking water
concent ration s are ba se d on residues of etha lflur alin parent only (see Health Effects Division

12 Metabolism Committee (MARC) report

, 5/25/1995 ) . T he 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 ( s ee Table 1 for details ).

Table 1

. Maximum es timated drinking water c oncentrations 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 et halfluralin.

Chemical Structure

Chemical N ame N

- ethyl

- ∀∀∀

- trifluoro

- N

- (2

- methylallyl)

- 2,6

- dinitro

- p

- toluidine
OR
N

- ethyl

- N

- (2

- melhyl

- 2

- propenyl)

- 2,6

- dinitro

4

- {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 C 13 H 14 F 3 N 3 O 4 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 in4 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, granu lar 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. Dill5 Table 4

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

Crop 1 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), Pre

emergence (All) & Post

1.70 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 generall y 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 formu lation 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 = N ot applicable (no variation of rates with soil texture classification specified).6 Crop 1 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.group 3 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. group 4 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

- F7 Crop 1 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 (Septe mber 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 us e of hexafluoropropylene copolymers in the formulation).
EC

- 1: Band/broadcast (not incorporated ) applied by Low pressure ground s prayer 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 Sona la n 10G into the top 2 to 3 inches of the fina l seedbed. Optional Methods of incorporation for Soybeans, Dry Beans and Peanuts on Medium and Coarse Textured Soils. Sonalan l0G may be applied as a surfac e application and incorporated by rainfall or sprinkler irrigation.

** Potatoes: For use in the Sta tes 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 An alysis 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 be ans/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 me thods and sources for estimating usage do vary from those in the Agency = discussed in the following paragraph.

According to Agency estimates, i n recent years (2004

- 2013 aggregated data) the major use sites in terms of average % crop treated (estimated) o f 10% or more are: 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 ). Usage on dry beans, peanuts, and sunflowers accounts for roughly 39%, 19%, and 26 % respectively of the total pounds of ethalfluralin

app lied 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 a nd 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 declini ng 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 <2.59 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 ref lect 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

- lev el 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 cr op 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 ar ea of mappe d 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 represen t an average fo r 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 perio d, (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 Agricu lture 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 esti mate 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 Met hod 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 : F ound 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

- risk

assessment#aquatic



### Aquatic Expo sure 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 Pestic i des in Water Calculator (PWC, version 1.52, 2/2/2016 ; not officially adopte d 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 gr oundwater (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 drift 4 and Ecological Exposure Assessments deposition directly in the receiving water body. T he physicochemical plus fate parameters and the use

specific input parameters for the SWCC surface water modeling and PRZM

- GW groundwater modeling are shown in Table 6 and Table 7 , respectively . The EDW Cs 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 model s

.

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

o C (E.g. MRID 48915601 study conducted at 20 o C.) 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 (K foc ) 3957 ml/g MRID 42437202 Koc value for sandy loam; lowest value among 4 soils 5

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 E uropean U nion 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 1 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
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/ superseded

development

- 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 EDW Cs by crop, ppb 6 )

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 Additiona l use sites represented by the Sunflower

- C ons ervative 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 dep th

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 exposur e modeling was done with the PWC that incorporates a peer

approved volatilization routine 7 . However, this information is for characterization, should future refinements be needed in the drinking water exposure modeling. The followin g 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
NCcornES TD

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 t he 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 wa ter 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

- assessing

pesticide

- 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 patte rn 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 Program18 Drinking water monitoring data c ollected 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 Surfac **e Water Monitoring**

The USGS NAWQA 8 data warehouse was searched on 12/23/2010 (the NAWQA data are now included in the WQP for which an updated search including NAWQ A 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 States 9

. 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):

• 11 3 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 follo wing 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 XI NG 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 bel ow 5 ppt, but levels below 5 ppt would be undetectable if present in most samples because the practical minimum detection lim it 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). Ethalflura lin 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 d ata 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 po unds 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 ethalfl uralin 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 exten t 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://ww w.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 associate d with a higher potential for offsite transport primarily via sediment but including to some exten t 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 app ear 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 physical20 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 u sing 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 0.2822 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 0.0823 Crops Represented App. Rate lb/A PCA
Factor Acute Chronic

yearly 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
Be nthic 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

- day25 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

- 0 1 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+0 0 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+0 0 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
2 8 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 (da ys) = 4.68010450792052

zero burial 0 benthic metab halflife (days) = 5.10938657155869 zero benthic hydrolysis 026 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 d epth 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 comp artment 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 SS27 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 a s 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 Wa ter = 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 4.50 E

- 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

- 0 1 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

- 0128 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+0 0 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 2 7 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 = 0.5 577 4.468 Due to Erosion = 0.0000 0.000 Due to Drift = 0.4423 3.543

*********************************************************************** Flow in/out Characteristics of Waterbody: Average Daily Run off 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 coefficient29 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 = fie ld 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 transfe r 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 = benthi c 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 = 1.0000000000000030 SWCC KS Corn Scenario (for assessment of soybean use)Output Summary31 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 Summary32 

### 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 \ In puts \ 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
1234 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

,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 5.035 4



### Summary of Reservoir Modeling of Ethalfluralin Modeling

– PA Corn scenario (Representing Soybean Use , Oct. 1 0 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. C ritical 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 runof f (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

p rocesses 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 reg ion, 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 po re 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 4.7536 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 cm37 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 generat ed 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 mechan ism 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 doe s 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) 038 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 Concentrations39 

### 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 Scenario40 Florida Jacksonville Area Scenario41 Georgia Coastal Plain Scenario42 North Carolina Coastal Plain Scenario43 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/ Vola t)
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