EXECUTIVE SUMMARY

This Tier I Drinking Water Assessment to support the Health Effects Division’s (HED’s)

Registration Review Assessment for flufenacet is being provided at this time with the following 

updates and revisions from previous assessments: 1.) To correct an error identified with the 

maximum application rates evaluated from the most recent drinking water assessment addressing 

estimated upper-bound surface water concentrations (DP Barcodes Nos. 318616 and 318629, 

dated October 4, 2006), 2.) To provide and discuss updated monitoring data that is available for 

flufenacet and its degradates, and 3.) To provide an evaluation for upper-bound ground water 

exposure that is consistent with current EFED policies and modeling tools.

Based on consultation with the Health Effects Division, flufenacet and its thiadone degrade are 

the main residues of concern that are considered in this drinking water assessment. The updated 

upper-bound EWDCs in surface water and ground water associated with flufenacet uses are 

summarized in Table 1. The results in Table 1 show that the driving exposure pathway for 

drinking water is found from flufenacet transport to surface water on an acute basis and ground 

water on a chronic basis. The results demonstrate flufenacet’s ability to move to both surface 

water and ground water sources. Furthermore, recent monitoring data (spanning from 2001 to

2013) shows several detections of flufenacet in surface water and ground water wells mainly at 

low-levels within the flufenacet’s main use area in the Midwest. However, there was one 

detection of flufenacet at a relatively high level (75 ppb) in a finished surface water sample in 

Indiana in 2007. These detections in monitoring data further support the potential for flufenacet 

exposure in both surface water and ground water.

Table 1. Summary of maximum upper-bound EDWCs (including flufenacet and 

flufenacet thiadone) for surface water and ground water associated with the existing uses 

of flufenacet.

Surface Water

Acute Chronic Cancer

29.871 9.071 5.211

Ground Water

Acute Chronic and Cancer

12.472 11.022

1. Based on SWCC IL Corn crop scenario 2. Based on PRZM-GW WI Sands scenario.

USE CHARACTERIZATION

Flufenacet is currently registered on 13 products1 and used on a variety of agricultural crops 

including corn for silage, sweet corn, field corn, grass seed, soybeans, triticale, and wheat. 

1 Flufenacet products compose of between 24 percent – 60 percent a.i. Flufenacet is co-formulated in four of these 

products comprising of the following compositions: 13.6%:54.4% Metribuzin:Flufenacet, 36%:24% 

Metribuzen:Flufenazet, 10%:48% Isoxaflutole:Flufenazet, 4.29%:35.71% Isoxaflutole:Fluefenacet.

2

 
Furthermore, there are flufenacet forestry uses including Douglas fir, Fraser fir, Grand fir, and

Noble fir trees. Flufenacet is only used as a pre-emergent herbicide and is applied as a broadcast 

surface spray, banded surface spray, or soil incorporated. Maximum single and seasonal 

application rates of flufenacet of between 0.3448 – 0.8019 lbs. a.i./A are specified on the 

proposed product labels (Table 2). Flufenacet usage is mainly confined to the corn and soybean 

belt of the Midwest, North Carolina, Southern High Plains, and Oregon.

Table 2. Summary of use information for flufenacet.

USE

MAX. 

SINGLE 

APP. 

RATE 

(lbs. a.i./A)

MAX. NUMBER OF 

APPS. and MIN. 

RETREATMENT 

INTERVAL

SEASONAL 

APP. RATE

(lbs. a.i./A) APPLICATION METHOD AND FORM 1

Corn (Sweet and 

Field)

0.8019 NS 0.8019

Broadcast Surface Spray

(Ground)

Banded Surface Spray

(Ground)

Soil Incorporated (1 – 2 

inches)

(DG, EC, FC, SC)

Soybean 0.4644 NS 0.4644

Broadcast Surface Spray

(Ground)

Banded Surface Spray

(Ground)

Soil Incorporated (1 – 2 

inches)

(DG, FC)

Wheat

Triticale 0.3448 NS 0.3448

Broadcast Surface Spray

(Ground)

(DG, FC)

3
Table 2. Summary of use information for flufenacet.

USE

MAX. 

SINGLE 

APP. 

RATE 

(lbs. a.i./A)

MAX. NUMBER OF 

APPS. and MIN. 

RETREATMENT 

INTERVAL

SEASONAL 

APP. RATE

(lbs. a.i./A) APPLICATION METHOD AND FORM 1

Grass Seed 0.4420 1 0.4420

Broadcast Surface Spray

(Ground)

Banded Surface Spray

(Ground)

Soil Incorporated (1 – 2 

inches)

(DG, FC)

Forestry (Douglas 

Fir, Fraser Fir, 

Grand Fir, Noble 

Fir)

0.6800 1 0.6800

Broadcast Surface Spray

(Aerial and Ground)

Banded Surface Spray

(Aerial and Ground)

Soil Incorporated 

(1 – 2 inches)

(DG) 1 Substance form identifiers: DG = Dispersible Granule, EC = Emulsifiable Concentrate, SC = Soluble 

Concentrate,

 FC = Flowable Concentrate

EXPOSURE ANALYSIS

• Surface Water

Estimated drinking water concentrations (EDWCs) in surface waters for the labeled flufenacet

applications are estimated using The Surface Water Concentration Calculator interface (SWCC 

version 1.092, dated March 6, 2014). Combined exposures from parent flufenacet and its

thiadone degradate are presented using the Formation-Decline method accounting for the 

presence of both compounds simultaneously in the environment over time. The SWCC is

available on-line at: http://www.epa.gov/oppefed1/models/water/#swcc. 

Percent crop areas (PCAs) are accounted for in EDWCs specific to each crop to factor in the 

portion of watersheds that are typically subject to pesticide loadings and subsequent transport to 

water bodies. The guidance, “Development and Use of Percent Cropped Area and Percent Turf 

Area Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update”, are used to 

4
determine PCA values for each crop (EPA, 2012). In this assessment, it is anticipated that 

flufenacet treatments to corn, soybeans, wheat triticale, and grass seed can all occur in the same 

watershed, but forestry applications of flufenacet are expected to occur in a separate watershed. 

Therefore, the maximum EDWCs are shown for each of these distinct groupings considering the 

anticipated percent coverages of watersheds potentially treated (e.g., percent crop area or PCA). 

Crop scenarios for the crops and forestry uses presented in this assessment represent the highest 

and most vulnerable exposure expected for flufenacet considering its potential loading for a 

certain use (e.g., maximum seasonal application rate) and sites possessing most vulnerable runoff

considering the extent of flufenacet’s use in the Midwestern Corn Belt, Southern Plains, North 

Carolina, and Oregon. Broadcast surface applications to bare ground are evaluated since this is 

the conservative application scenario for runoff. The fate parameters and use-specific input

parameters for the SWCC surface water modeling are shown in Table 3. The EDWCs of 

flufenacet and its thiadone degradate in surface water are shown for aerial and ground

applications in Table 4. The SWCC output files are provided in Appendix B.

Table 3. SWCC input parameter values used for surface water aquatic exposure estimation with 

flufenacet and its thidadone degradate.

SWCC Input Parameter Input Value and Unit

(Flufenacet/Thiadone 

Degradate) 

Source

Physical Chemical Properties

Molecular Weight (g/mol) 363/170 MRID 43441102 and 43850001

Vapor Pressure (torr) 2.40 x 10-11/1.5x10-2 MRID 43441102 and 43850001

Solubility in Water (mg/L) 56/200,000 MRID 43441102 and 43850001

Soil-Water Partition Coefficient (Koc)

(mL/g)

434.4/43.5 Average values

MRID 43441137 and 43441140 

Environmental Fate Properties

Hydrolysis at pH7 (t1/2) Stable/Stable MRID 43441134 and 45796107

Aerobic soil metabolism (t1/2),

Reference Temperature, and 

Degradate Molar Formation Fraction

48.2 days at 25°C/

2.77 days at 25°C

Deg. Molar Formation 

Frac.:1.0

MRID 43441141, 43441135, 

43850058, & 48604493

Upper 90TH percentile confidence 

interval1

Aerobic aquatic metabolism (t1/2), 

Reference Temperature, and 

Degradate Molar Formation Fraction

77.1 days at 25°C/160 days at 

25°C

Deg. Molar Formation 

Frac.:1.0 

MRID 45796112, 44580203, & 

45796111

Upper 90TH percentile confidence 

interval1

Anaerobic aquatic metabolism (t1/2)

and Reference Temperature

492 days at 25°C /303 days at 

25°C

MRID 43850060, 43850061, & 

45796110

5
Table 3. SWCC input parameter values used for surface water aquatic exposure estimation with 

flufenacet and its thidadone degradate.

SWCC Input Parameter Input Value and Unit

(Flufenacet/Thiadone 

Degradate) 

Source

Deg. Molar Formation 

Frac.:1.0

Upper 90th percentile confidence 

interval1

Aqueous Photolysis (t1/2) and 

Reference latitude

Stable at 45°N/Stable at 45°N MRID 43850056 and 46997401

Application Methods and Crop Management Input Parameters

Crop Scenario and Weather IL Corn

14842.dvf 

(Peoria, IL)

OR Xmas Tree 

24232.dvf 

(Salem, OR)

Crop scenarios presented consider a 

combination of maximum loading and 

vulnerable runoff site for flufenacet’s 

use confined to the Midwestern Corn 

Belt, Southern Plains, Oregon, and 

North Carolina. Forestry use scenario 

shown separately considering these 

uses are anticipated to be in unique 

watersheds.

Application Rate IL Corn

0.898 kg/ha

OR Xmas Tree

0.7616 kg/ha 

Maximum single application rate 

specified on product labels

Number of Applications and 

Retreatment Interval

IL Corn, OR XmasTree

1 application

Based on maximum seasonal app. 

rates (specified in Table 2) and 

minimum retreatment intervals 

specified in product labels.

Application Date IL Corn, OR XmasTree

15 day before crop emergence

Product labels

PCA IL Corn

0.95

OR Xmas Tree

1.0 

Maximum national PCA for all 

agricultural and turf use combinations 

from Table 5 of, “Development and 

Use of Percent Cropped Area and 

Percent Turf Are Adjustment Factors 

in Drinking Water Exposure 

Assessments: 2012 Update”

Application Methods IL Corn

Ground (Bare Surface)

OR Xmas Tree

Ground (Bare Surface)

Product labels 

Application Efficiency IL Corn

Ground apps.: 0.99

EFED input parameter guidance for 

aerial and ground applications

6
Table 3. SWCC input parameter values used for surface water aquatic exposure estimation with 

flufenacet and its thidadone degradate.

SWCC Input Parameter Input Value and Unit

(Flufenacet/Thiadone 

Degradate) 

Source

OR Xmas Tree

Aerial apps.: 0.95 

Spray Drift Fraction IL Corn

Ground apps.: 0.066 

OR Xmas Tree

Aerial apps.: 0.135 

Spray drift fraction for aerial and 

ground applications from Table 2 of 

EPA, 2013, “Guidance on Modeling 

Offsite Deposition of Pesticides via 

Spray Drift”.

1

 The upper 90th percentile half life calculated as follows: t1/2 input = tt1/2 ����� + (t90, n-1 x σ)

 n1/2

where tt1/2 ����� is the mean of the set of half lives from each study, t90, n-1 is the one-sided t value for the 90th percentile 

level, σ is the standard deviation of the set of half lives determined from each study, and n is the sample size of the 

set of half lives determined from each study.

Table 4. SWCC estimated upper bound concentrations in surface water 

(flufenacet-equivalent ppb).

Crop Scenarios and 

App. Method1 PCA

Annual 

Peak 

(Acute)1

Annual 

Mean 

(Chronic)1

30-year Mean 

(Cancer)

Flufenacet

IL Corn 0.95 26.32 6.76 3.91

OR Xmas Tree 1.0 13.40 5.62 3.26

Thiadone Degradate

IL Corn 0.95 3.55 2.31 1.30

OR Xmas Tree 1.0 2.71 2.35 1.62

Total

IL Corn 0.95 29.87 9.07 5.21

OR Xmas Tree 1.0 16.11 7.97 4.88

*Bold text indicate maximum values. 1 One-in-ten year estimated value.

• Ground Water

Ground water estimated concentrations resulting from the existing uses of flufenacet are 

estimated using the PRZM-GW (version 1.07, March 6, 2014) will be used to evaluate ground 

water exposure. PRZM-GW is publically available on-line at 

http://www.epa.gov/oppefed1/models/water/#przm_gw. Results from the long-standing tier I 

SCI-GROW model (Screening Concentration in GRound Water model, Version 2.3, May 16, 

7
2006) will also be shown in comparison with the PRZM-GW modeling results according to 

EFED guidance related to the evaluation period for the recent release of PRZM-GW. SCIGROW is publically available on-line at http://www.epa.gov/oppefed1/models/water/#scigrow. 

Tables 5 and 6 show the input parameter values used in PRZM-GW and its predicted

concentrations of flufenacet and the thiadone degradate in ground water. The residue summation 

approach was used to calculate thiadone concentrations considering its maximum formation 

fraction in soil from the aerobic soil metabolism study (3.9 percent of applied, MRID No. 

43441135) and degradate from parent ratio of molecular weights. Tier I scenarios are run in this 

assessment to capture upper-bound screening exposure based on vulnerable environmental 

conditions. Incorporated applications to 2 inches below ground are evaluated as this is the 

conservative application method leading to ground water exposure. The PRZM-GW output files 

for both scenarios are provided in Appendix C.

Table 5. PRZM-GW input parameter values for physical chemical and fate 

properties for flufenacet and its thidadone degradate ground water exposure 

estimation.

PRZM/EXAMS Input 

Parameter

Input Value and Unit Source

Pesticide Properties

Hydrolysis at pH7 (t1/2) Stable/Stable MRID 43441134 and 45796107

Surface soil metabolism 

(t1/2) at 25°C

48.2 days/2.77 days MRID 43441141, 43441135, 

43850058, & 48604493

Upper 90TH percentile 

confidence interval1 

Soil-Water Partition 

Coefficient (Koc)

(mL/g)

434.4/43.5 Average values

MRID 43441137 and 43441140 

Application Methods and Crop Management Input Parameters

Crop Scenarios and Weather WI Sands: w14920 (La Crosse, WI)

NC Coastal: w13722 (Raleigh, NC)

GA Coastal: w93805 (Tallahasse, FL)

Delmarva Peninsula: w13781 (Wilmington, DE)

FL Citrus: w12842 (Tampa, FL)

FL Potato: w13889 (Jacksonville, FL)

Application Date 15 days before crop 

emergence

Product label

Application Rate 0.864 kg/ha/0.02kg/ha2 Maximum single/seasonal

application rate out of all uses 

proposed for ornamentals on 

product labels Number of Applications and 3

Retreatment Interval

1 application

Application Methods Incorporated at 2 inches 

below ground

expected to result in the most 

conservative EDWCs

8
1

 The upper 90th percentile half life calculated as follows: t1/2 input = tt1/2 ����� + (t90, n-1 x σ)

 n1/2

where tt1/2 ����� is the mean of the set of half lives from each study, t90, n-1 is the one-sided t value for the 90th percentile 

level, σ is the standard deviation of the set of half lives determined from each study, and n is the sample size of the 

set of half lives determined from each study. 2 Thiadone equivalent application rate calculated with residue summation method based on its maximum formation 

fraction in soil from the aerobic soil metabolism study (MRID No. 43441135) and degradate from parent ratio of 

molecular weights (Thiadone equivalent App. Rate = 0.898 kg/ha x 363.6 g-mol-1

/170g-mol-1 x 0.039 = 0.02 

kg/ha). According to the residue summation method, the flufenacet portion of the application rate is calculated as 

follows (Flufenacet App. Rate = 0.898 kg/ha – (0.898 kg/ha x 0.039) = 0.864 kg/ha.

Table 6. PRZM-GW estimated upper bound concentrations in ground water 

(flufenacet-equivalent ppb)

Tier I Scenario

Highest Daily Value

(Acute)

Post-Breakthrough 

Average

(Chronic and Cancer)

Flufenacet

WI Sands 12.40 11.00

NC Coastal 1.19 1.00

GA Coastal 0.62 0.60

FL Citrus 7.17 6.85

FL Potato <0.01 <0.01

Delmarva Peninsula 2.78 2.22

Thiadone Degradate

WI Sands 0.06 0.02

NC Coastal <0.01 <0.01

GA Coastal <0.01 <0.01

FL Citrus 0.02 <0.01

FL Potato <0.01 <0.01

Delmarva Peninsula 0.07 0.02

Total

WI Sands 12.47 11.02

NC Coastal 1.19 1.00

GA Coast 0.62 0.60

FL Citrus 7.19 6.85

FL Potato <0.01 <0.01

Delmarva Peninsula 2.85 2.24

*Bolded values show the highest ground water EDWC.

The SCI-GROW model (Screening Concentration in GRound Water model, Version 2.3, May 

16, 2006) are also shown in comparison with the PRZM-GW modeling results according to 

current EFED guidance related to the evaluation period for the recent release of PRZM-GW. 

Tables 7 and 8 show the input parameter values used in SCI-GROW and its predicted

concentrations of flufenacet and the thiadone degradate in ground water, respectively. The 

9
ground water concentrations generated by SCI-GROW can be considered suitable for both acute 

and chronic exposures. The SCI-GROW output files for both scenarios are provided in 

Appendix C. The EDWCs from PRZM-GW are higher and as such are used as the basis for 

ground water exposure concentrations in this assessment. 

Table 7. SCI-GROW input parameter values for physical chemical and fate 

properties used for flufenacet and thiadone degradate.

SCI-GROW Input Parameter Input Value and Unit Source

Application Methods and Crop Management Input Parameters

Maximum Application Rate

(lbs. a.i./A)

0.802 Product Labels

Number of Applications 1 Product labels

Physical Chemical Properties

Soil-Water Partition Coefficient 

(Koc)

43.5 mL/g Thiadone degra’s lower mean 

Koc more conservative.

MRID 43441137 and 43441140

Environmental Fate Properties

Aerobic soil metabolism (t1/2) 48.2 days Total half-life between 

flufenacet and thiadone 

degradate.

MRID 43441141, 43441135, 

43850058, & 48604493

Table 8. SCI-GROW estimated upper bound concentrations for 

flufenacet and its thiadone degradate in ground water (flufenacetequivalent ppb).

Acute Chronic and Cancer

0.93

WATER MONITORING DATA

There are some water monitoring data available for flufenacet and its degradates in surface 

water, stream water, and ground water from the USGS National Water Quality Assessment 

(NAWQA) and EPA’s Storage and Retrieval Warehouse (STORET) monitoring datasets. In 

general, these monitoring data indicate that the SWCC and PRZM-GW modeling provide 

reasonably protective estimates of drinking water exposure. In addition, there are additional 

monitoring data in untreated drinking water, finished drinking water, as well ground water in the 

EPA Pesticide Database Program (PDP). With all of these data, it should be noted that there are 

no indications whether or not these data represent targeted sampling observations. However, 

10
there is also a targeted Prospective Ground Water Study submitted by the registrant for 

flufenacet and its degradates available as well (MRID No. 46997402).

The NAWQA monitoring dataset encompasses 1,845 samples of parent flufenacet at various 

surface water and ground water monitoring sites for the period between 2001and 2012. 

Flufenacet degradates are not known to have been sampled. The nature of detections of 

flufenacet in the NAWQA data are summarized below:

• Flufenacet was detected in stream water 14 times at various sites in Iowa, Nebraska, 

Ohio, Maryland, and South Carolina. Concentrations of up to 0.31 ppb were detected in 

Dodge County, Iowa.

• Flufenacet was detected in wells 3 times at various sites in Iowa and Minnesota. 

Concentrations of up to 0.04 ppb in ground water were detected in Buena Vista County, 

Iowa.

• Flufenacet was detected twice at stream sediment pore water, both instances in Nebraska, 

with concentrations of up to 0.74 ppb detected in Colfax County.

• Flufenacet was detected at one distributed drinking water facility in Sandova County, 

NM at concentrations of up to 0.04 ppb. Details on the exact siting of concentrations 

within influent or finished water was not provided.

An expanse of water monitoring information related to sampling of flufenacet’s oxalate 

degradate in Minnesota is available from the STORET database. The sampling occurred 

between the years 2010 – 2013. No detections were found out of 2,069 samples.

There is a further expanse of monitoring data available from EPA’s PDP from drinking water 

facilities and ground water well for both flufenacet and its oxalate degradate. The monitoring 

data span from 2005 to 2013 and are summarized below:

• Flufenacet was only detected once in finished surface water out of 964 samples. 

However, the magnitude of detection was really large at 75 ppb. This detection occurred 

in Indiana in 2007. Flufenacet was not sampled in ground water in the PDP.

• Flufenacet oxalate was detected 75 out of 1,363 samples in finished surface water, 71 out 

of 1,317 samples in untreated surface water, and 2 out of 1,767 samples in ground water. 

Flufenacet oxalate was found in concentrations up to 26 ppb in finished surface water, 

21.3 ppb in untreated surface water, and 13 ppb in ground water. The highest magnitude 

and frequency of detections occurred with a vast majority within Ohio. However, there 

were a few detections from a drinking water treatment facility in Louisiana and one 

detection in a ground water well located in Georgia.

11
Furthermore, there is a targeted prospective ground water study conducted in shallow wells (15 

to 25 ft. below ground surface) and deep wells (25 to 30 ft. below ground surface) for flufenacet, 

and its thiadone, oxalate, alcohol, and sulfonic acid degradates (MRID No. 46997402). The 

monitoring study was conducted concurrent to a pre-emergent application of Flufenacet in a corn 

field possessing silt loam soil located in the town of Minden in Central Nebraska during June of 

1995. The monitoring data with each constituent is described below:

• Flufenacet was only detected one time at 0.04 ppb within 30 days of the application. 

• The thiadone degradate was detected extensively but at low levels starting at 119 days 

after the application in both in shallow and deep wells. Concentrations ranged as high 

0.18 ppb at 501 days after the application. The thiadone degradate was not detected after 

1,155 days after the application.

• The alcohol degradate of flufenacet was only detected one time at 0.02 ppb at 994 days 

after the application.

• The oxalate degradate was detected extensively but at low levels starting at 93 days after 

the application only in shallow wells. Concentrations ranged as high 0.12 ppb at 149 days 

after the application. The oxalate degradate was not detected after 501 days after the 

except for one trace isolated detection of 0.02 ppb at 994 days after the application.

• The sulfonic acid degradate was detected extensively but at low levels starting at 93 days 

after the application only in shallow wells. Concentrations ranged as high 0.66 ppb as late 

as 534 days after the application. The sulfonic acid degradate concentration of 0.37 ppb 

in shallow wells and 0.22 ppb were detected at the termination of the study at 1,473 days 

(4 years) after the application.

MODELING AND MONITORING CHARACTERIZATION

In general, both flufenacet EDWCs of surface water and ground water are higher by a large 

margin than the highest monitoring concentrations observed. For surface water, this may be due 

to a wide number of factors relating to lower vulnerabilities with rainfall, runoff, and drainage 

that may have been present at the surface water monitoring sites since the modeling scenarios 

depict the most vulnerable sites. Furthermore, it is a likelihood that surface water monitoring are 

not spatially or temporally targeted to applications especially as evident in their irregular 

sampling intervals in many cases. The ground water EDWC is purely a screening value for the 

entire country and is not specific for a certain crop. Therefore, ground water concentrations of 

flufenacet are expected to be lower than depicted by EDWCs and closer to the values as 

observed in the prospective ground water study. However, it should be noted that the site of this 

study was in Central Nebraska. Rainfall may occur more regularly at locations further east in the 

corn belt where flufenacet is used. Therefore, flufenacet ground water concentrations may be 

higher than observed in the Nebraska prospective ground water study. 

12
It should be noted that there was one isolated detection of flufenacet, identified in PDP data, at 

relatively high levels of 75 ppb in finished water at a water treatment facility in Indiana in 2007. 

While this concentration is higher than the upper-bound EDWC provided in this assessment, this 

flufenacet concentration is isolated and as such may be reflective of a rare set of circumstances 

such as a high-end runoff event which occurred in the area at the time of this detection. It is 

uncertain whether this value would represent a one-in-ten year peak concentration given the 

relatively small temporal scope of the monitoring data available for flufenacet. However, this 

detection in Indiana provides further evidence of flufenacet surface water exposure in an area 

where it is highly used.

REFERENCES

Barrett, M. 1997. Proposal For a Method to Determine Screening Concentration Estimates for 

Drinking Water Derived from Ground Water Studies. EPA Office of Pesticide Programs. 

Washington, DC.

U.S. Environmental Protection Agency 2012. Guidance for using PRZM-GW in Drinking Water 

Exposure Assessments. U.S. Environmental Protection Agency, Office of Prevention, Pesticides 

and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division. 

October 15, 2012. 

U.S. Environmental Protection Agency 2012.. Development and Use of Percent Cropped Area 

and Percent Turf Area Adjustment Factors in Drinking Water Exposure Assessments: 2012 

Update. EPA Office of Pesticide Programs. Washington, DC.

U.S. Environmental Protection Agency 2012. Guidance for using PRZM-GW in Drinking Water 

Exposure Assessments. U.S. Environmental Protection Agency, Office of Prevention, Pesticides 

and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division. 

October 15, 2012. 

U.S. Environmental Protection Agency 2014. Surface Water Concentration Calculator User 

Manual, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, 

Environmental Fate and Effects Division. July 1, 2014. 

13
APPENDIX A. ENVIRONMENTAL FATE AND TRANSPORT SUMMARY

Flufenacet can exist both in the dissolved phase and sorbed phase in soil, with Koc values ranging 

from 209 – 762 mL/g (MRID No. 43441137) and aqueous solubility value of 56 mg/L. 

Therefore, flufenacet has the ability to reach surface water sources via runoff and erosion 

processes and groundwater sources via leaching as well. Flufenacet will not likely exist in the 

vapor-phase given its vapor pressure of 2.11 x 10-7 torr and Henry’s Law Constant of 2.12 x 10-8

atm•m3

/mol. Flufenacet is moderately persistent is soil and water with primary decline occurring 

due to biodegradation in aerobic environments over time. Flufenacet half-lives range from 23.1 

days – 63.6 days in aerobic soil environments (MRID Nos. 43441141, 43441135, and 43850058) 

and 18 – 77 days in aerobic aquatic environments (MRID Nos. 45796112 and 44580203). 

Flufenacet is stable in anaerobic soil environments (MRID No. 43850059) and persistent in 

anaerobic aquatic systems with a half-life of 492 days (MRID No. 43850060). Flufenacet is 

stable due to abiotic degradation processes including hydrolysis and photolysis in water and soil 

(43441134, 43850056, and 43850057). The molecular structure of flufenacet is shown in in 

Figure A-1 below.

F

F

F

F

C H 3

C

H

H C3

N

N

N

S

O

C

H 2

O

Figure A-1. Molecular structure for flufenacet.

In general, flufenacet breaks down in both soil and water by separating into anilide and thiadone 

components via cleavage of the CH2 linkage (MRID Nos. 43441141, 43441135, 43850058, 

45796112, 44580203). The entire thiadone group (right hand side of the parent molecule) 

remains completely entact and is persistent in aerobic and anaerobic aquatic environments with 

half-lives ranging between 160 - 303 days (MRID Nos. 4579110 and 45796111), but is more 

labile in aerobic soil environments with half-lives ranging 2.0 – 2.8 days (MRID No. 45796109). 

In both soil and water, the anilide group (left hand side of the parent molecule) exhibits more 

complex serial degradation processes mainly to alcohol, methylsulfoxide, oxylate, and sulfonic 

acid by-products. The anilide by-products described above are all detected at major levels 

(greater than 10 percent of applied) in the aerobic soil, anaerobic soil, aerobic aquatic, and 

anaerobic aquatic metabolism laboratory studies (MRID Nos. 43441141, 43441135, 43850058, 

45796112, and 44580203). However, the thiadone degradate is only detected at major levels in 

water likely given its high persistence in aerobic and anerobic aquatic environments and more 

labile nature in aerobic soil environments (MRID Nos. 43441141, 43441135, 43850058, 

14
45796112, 44580203, 4579110, 45796111, and 45796109). Please refer to Tables A-1 and A-2

for detailed information on the formation and decline for all of the degradates in soil and water.

Both the thiadone degredate and flufenacet have been identified as the residues of concern in 

drinking water in consultation with HED. Given the thiadone degradate’s highly labile nature in 

soil, substantial translocation of the thiadone degradate via runoff and leaching to surface water 

and ground water, respectively, is not likely. However, the thiadone degradate is expected to 

form at high levels from biodegradation of flufenacet residues which reach surface water. 

Once the thiadone degradate forms, it is likely to be persistent in water for a long duration as 

indicated by its half-life of 160 – 303 days in aerobic and anaerobic aquatic environments. It 

should be noted that as compared to flufenacet, a more substantial portion of the thiadone 

degradate material would likely remain in the water column rather than sorbed to sediment given 

its Koc values in the range of 29 – 58 (MRID No. 43441140). The thaidone degradate in water is 

not anticipated to exist in the vapor-phase given its Henry’s Law Constant of 1.2 x 10-7

atm•m3/mol. The molecular structure of the thiadone degradate is shown in Figure A-2.

F

F

F

O

N

H

S

N

Figure A-2. Molecular structure for the flufenacate thiadone degradate.

15
Table A-1. Flufenacet transformation products

Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Aerobic Soil Metabolism

Transformation Product 1

Thiadone

5-(Trifluoromethyl)-1,3,4-thiadiazol-2(3H)-

one

or

5-Trifluoromethyl-1,3,4-thiadiazol-2(3H)-one

or

3-Trifluoromethyl-1,3,4-thiadiazol-2(3H)one

3.9% @ 7 d 0.9% @ 368 d 43441135

162-1

Thiadiazole label/sandy loam

Anaerobic Aquatic Metabolism

16.0% @ 99 d 16.0% @ 99 d 43850061

162-3

Thiadiazole label/pond watersandy loam 

Aerobic Aquatic Metabolism

84.3% @ 55 d 68.7% @ 156 d 45796112

162-4

Thiadiazole label/pond watersilty clay sediment (NESA; entire 

system)

63.8% @ 100 d 54.2% @ 156 d 45796112

162-4

Thiadiazole label/pond watersilty clay loam sediment (BRP; 

entire system)

Field Dissipation Studies

Below LOD (<0.01 ppm) 

throughout study

Below LOD (<0.01 ppm) 

@ 554 d

43850062

164-1

North Carolina loamy sand (0-6 

inches)

Below LOD (<0.01 ppm) 

throughout study

Below LOD (<0.01 ppm) 

@ 466 d

43850063

164-1

Wisconsin loamy sand (0-6 

inches)

Prospective Ground Water Study

Below the LOQ (10 μg/kg) 

throughout the study

Below the LOQ (10 

μg/kg) at 489 d

45907901

166-1

Sandy loam (0-6 inches)

16
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Transformation Product 2

Flufenacet methylsulfide

4-Fluoro-N-methylethylanaline 

methylthioacetamide

Aerobic Aquatic Metabolism

11.4% @ 157 d 11.4% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; entire 

) 4.5% @ 157 d 4.5% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

Transformation Product 3

Flufenacet oxalate

[(4-Fluorophenyl)(1-

methylethyl)]amino]oxoacetic acid

or

[(4-Fluorophenyl)(1-methylethyl)]amino]2-

oxoacetic acid

Soil Photolysis

irradiated- 0.6% @ 30 d

dark- 4.6% @ 30 d

irradiated- 0.6% @ 30 d

dark- 4.6% @ 30 d

43850057

161-3

Phenyl label/sandy loam

Aerobic Soil Metabolism

26.5% @ 365 d 26.5% @ 365 d 43441141

162-1

Phenyl label/sandy loam 

6.6% @ 28 d Not detected @ 120 d 43850058

162-1

Phenyl label/loamy sand

17
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

15.6% @ 28 d Not detected @ 120 d 43850058

162-1

Phenyl label/silt loam 

(Laacherhof)

10.0% @ 28 d Not detected @ 120 d 43850058

162-1

Phenyl label/silt loam (Hofchen)

13.0% @ 46 d 11.7% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

7.6% @ 88 d 7.6% @ 88 d 43850066

162-1

Phenyl label/sandy loam

Anaerobic Soil Metabolism

14.5% @ 60 d 9.9% @ 210 d 43850059

162-2

Phenyl label/sandy loam

Aerobic Aquatic Metabolism

4.6% @ 157 d 4.6% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; entire 

system)

5.4% @ 157 d 5.4% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

18
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Terrestrial Field Dissipation

0.1 ppm @ 5 and 369 d Below LOD (<0.01 ppm) 

@ 554 d

43850062

164-1

North Carolina loamy sand (0-6 

inches)

0.01 ppm @ 27 and 369 d Below LOD (<0.01 ppm) 

@ 466 d

43850063

164-1

Wisconsin loamy sand (0-6 

inches)

Transformation Product 4

Flufenacet sulfonic acid 

4-Fluoro-N-methylethylaniline-sulfoacetamide

or

N-Fluoro-N-methylethylaniline-sulfoacetamide

or

2-[(4-Fluorophenyl)(1-methylethyl)amino]-

oxoethylsulfonic acid

Soil Photolysis

irradiated- 0.4% @ 15 d

dark- 2.2% @ 30 d

irradiated- 0.3% @ 30 d

dark- 2.2% @ 30 d

43850057

161-3

Phenyl label/sandy loam

Aerobic Soil Metabolism

7.7% @ 180 d 5.3% @ 365 d 43441141

162-1

Phenyl label/sandy loam 

25.4% @ 100 d 22.6% @ 120 d 43850058

162-1

Phenyl label/loamy sand

26.3% @ 100 d 21.8% @ 120 d 43850058

162-1

Phenyl label/silt loam 

(Laacherhof)

13.5% @ 100-120 d 13.5% @ 120 d 43850058

162-1

Phenyl label/silt loam (Hofchen)

2.4% @ 88 d 2.4% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

1.3% @ 88 d 1.3% @ 88 d 43850066

162-1

Phenyl label/sandy loam

19
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Anaerobic Soil Metabolism

6.6% @ 30 d 4.5% @ 210 d 43850059

162-2

Phenyl label/sandy loam

Aerobic Aquatic Metabolism

1.65% @ 157 1.65% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; water 

only)

3.2% @ 157 d 3.2% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

Terrestrial Field Dissipation

Below LOD (<0.01 ppm) 

throughout study

Not analyzed @ 554 d 43850062

164-1

North Carolina loamy sand (0-6 

inches)

0.02 ppm @ 14 to 27 d Below LOD (<0.01 ppm) 

@ 466 d

43850063

164-1

Wisconsin loamy sand (0-6 

inches)

Prospective Ground Water

Below the LOQ (10 μg/kg) 

throughout the study

Below the LOQ (10 

μg/kg) at 489 d

45907901

166-1

Sandy loam (0-6 inches)

Transformation Product 5

Flufenacet methylsulfoxide

4-Fluoro-N-methylethylanaline 

Soil Photolysis

irradiated- 0.7% @ 30 d

dark- 0.6% @ 30 d

irradiated- 0.7% @ 30 d

dark- 0.6% @ 30 d

43850057

161-3

Phenyl label

20
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

methylsulfenylacetamide Aerobic Soil Metabolism

0.6% @ 28 d Not detected @ 365 d 43441141

162-1

Phenyl label/sandy loam 

1.1% @ 28-56 d Not detected @ 120 d 43850058

162-1

Phenyl label/loamy sand

3.5% @ 56 d 0.7% @ 120 d 43850058

162-1

Phenyl label/silt loam 

(Laacherhof)

1.5% @ 56 d 0.2% @ 120 d 43850058

162-1

Phenyl label/silt loam (Hofchen)

1.3% @ 88 d 1.3% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

0.9% @ 88 d 0.9% @ 88 d 43850066

162-1

Phenyl label/sandy loam

Aerobic Aquatic Metabolism

3.2% @ 157 d 3.2% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; entire 

system)

2.2% @ 120 d 1.7% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

21
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Transformation Product 6

Flufenacet methylsulfone

N-(fluorophenyl)-N-(1-methylethyl)-2-

(methylsulfonyl)acetamide

or

4-Fluoro-N-methylethylaniline 

methylsulfonylacetamide

Aerobic Soil Metabolism

6.6% @ 100 d 4.7% @ 120 d 43850058

162-1

Phenyl label/loamy sand

4.3% @ 120 d 4.3% @ 120 d 43850058

162-1

Phenyl label/silt loam 

(Laacherhof)

5.6% @ 120 d 5.6% @ 120 d 43850058

162-1

Phenyl label/silt loam (Hofchen)

0.5% @ 46 d 0.3% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

Aerobic Aquatic Metabolism

6.4% @ 100 d 5.3% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; entire 

system)

7.2% @ 120 d 3.8% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

Transformation Product 7

Flefenacet thioglycolate sulfoxide

Aerobic Soil Metabolism

3.7% @ 180 d 2.8% @ 365 d 43441141

162-1

Phenyl label/sandy loam 

22
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

4-Fluoro-N-methylethyl-aniline 

sulfenyldiacetic acid amide 3.3% @ 56 d Not detected @ 120 d 43850058

162-1

Phenyl label/loamy sand

5.5% @ 28 d Not detected @ 120 d 43850058

162-1

Phenyl label/silt loam 

(Laacherhof)

1.9% @ 28 d Not detected @ 120 d 43850058

162-1

Phenyl label/silt loam (Hofchen)

Anaerobic Soil Metabolism

2.6% @ 30 d Not detected @ 210 d 43850059

162-2

Phenyl label/sandy loam

Aerobic Aquatic Metabolism

2.0% @ 157 d 2.0% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; entire 

system)

1.89% @ 60 d 1.38% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

Transformation Product 8

Flufenacet alcohol

N-(4-fluorophenyl)-2-hydroxyacetamide

or 

N-(4-Fluorophenyl)-2-hydroxy-N-(1-methylSoil Photolysis

irradiated- 1.0% @ 30 d

dark- 0.4% @ 30 d

irradiated- 1.0% @ 30 d

dark- 0.4% @ 30 d

43850057

161-3

Phenyl label

Aerobic Soil Metabolism

2.1% @ 44-65 d Not detected @ 365 d 43441141

162-1

Phenyl label/sandy loam 

23
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

ethyl)acetamide

8.1% @ 88 d 8.1% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

21.2% @ 88 d 21.2% @ 88 d 43850066

162-1

Phenyl label/sandy loam

Anaerobic Soil Metabolism

1.4% @ 153 d 0.9% @ 210 d 43850059

162-2

Phenyl label/sandy loam

Aerobic Aquatic Metabolism

0.7% @ 120 d 0.6% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; entire 

system)

1.3% @ 157 d 1.3% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

Terrestrial Field Dissipation

0.4 ppm @ 1 d Below LOD (<0.01 ppm) 

@ 554 d

43850062

164-1

North Carolina/Pocalla loamy 

sand

0-6 inches

0.01 ppm @ 1 to 14 d Below LOD (<0.01 ppm) 43850063 Wisconsin/ Dickinson sandy loam

24
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

@ 466 d 164-1 0-6 inches

Prospective Ground Water

Below the LOQ (10 μg/kg) 

throughout the study

Below the LOQ (10 

μg/kg) at 489 d

45907901

166-1

Transformation Product 9

Flufenacet chloroacetanilide

N-(4-Fluorophenyl)-2-chloro-N-(1-

methylethyl)acetamide

Aerobic Soil Metabolism

5.1% @ 44 d Not detected @ 365 d 43441141

162-1

Phenyl label/sandy loam 

0.4% @ 1 d 0.2% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

0.4% @ 27 d 0.2% @ 88 d 43850066

162-1

Phenyl label/sandy loam

Transformation Product 10

Flufenacet N-isomer

N-(4-Fluorophenyl)-N-(1-methylethyl)-5-oxo2-(trifluoromethyl)-1,3,4-thiadiazole-4(5H)-

acetamide

Soil Photolysis

irradiated- 1.6% @ 8-15 d

dark- 1.8% @ 15 d

irradiated- 1.6% @ 30 d

dark- 1.5% @ 30 d

43850057

161-3

Phenyl label

Aerobic Soil Metabolism

2.0% @ 46 d 0.7% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

25
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

1.4% @ 88 d 1.4% @ 88 d 43850066

162-1

Phenyl label/sandy loam

Transformation Product 11

Flufenacet thiol dimer

2,2'-Dithiobis[N-(4-fluorophenyl)-N-(1-

methylethyl)acetamide]

Aerobic Soil Metabolism

0.8% @ 27 d 0.7% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

Transformation Product 12

Flufenacet thioglycolate

4-Fluoro-N-methylethylaniline thiodiacetic 

acid amide

Anaerobic Soil Metabolism

1.7% @ 60 d 1.4% @ 210 d 43850059

162-2

Phenyl label/sandy loam

Transformation Product 13

Flufenacet amine acetate

N-(4-Fluorophenyl)-N(1-

methylethyl)acetamide

Anaerobic Aquatic Metabolism

1.6% @ 63-91 d 1.6% @ 91 d 43850060

162-3

Phenyl label/pond water-sandy 

loam 

Transformation Product 14

Thiadone-acetate

5-Trifluoromethyl-1,3,4-thiadiazol-2-oxy 

acetic acid

Anaerobic Aquatic Metabolism

1.8% @ 99 d 1.8% @ 99 d 43850061

162-3

Thiadiazole label/pond watersandy loam 

26
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Transformation Product 15

FAIOCS and Flufenacet acid

Cysteine conjugate of 4'Fluoro-Nisopropanolacetanilide and FOE oxalate

Fish BCF

0.258 mg/kg @ 21 d (nonedible)0.191 mg/kg @ 28 d 

(non-edible)

43441127/

43441139

165-4

Pheny label/bluegill (Lepomis 

macrochirus)

Transformation Product 16

FACSO

3-[[2-4-[(4-Fluorophenyl)(1-

methylethyl)amino]2-oxoethyl]sulfinyl]analine

Fish BCF

0.327 mg/kg @ 21 d (nonedible)0.114 mg/kg @ 28 d 

(non-edible)

43441127/

43441139

165-4

Pheny label/bluegill (Lepomis 

macrochirus)

Transformation Product 17

FANACSO

N-Acetyl-3-[[2-[4-fluorophenyl)(1-

nethylethyl)amino]-2-oxoethyl]sulfinyl]alanine

Fish BCF

0.444 mg/kg @ 21 d (nonedible)0.097 mg/kg @ 28 d 

(non-edible)

43441127/

43441139

165-4

Pheny label/bluegill (Lepomis 

macrochirus)

Transformation Product 18

FOE GSH

N-[2-(Carboxmethyl)amino]-1-[[[[2-[(4-

fluorophenyl)(1-methylethyl)amino]-2-

oxoethyl]thio]methy]-2-oxoethyl]glutamine

Fish BCF

0.355 mg/kg @ 21 d (nonedible)0.239 mg/kg @ 28 d 

(non-edible)

43441127/

43441139

165-4

Pheny label/bluegill (Lepomis 

macrochirus)

27
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Transformation Product 19

FACS

S-[2-[(4-Fluorophenyl)(1-methylethyl)amino]-

2-oxoethyl]cysteine

Fish BCF

5.719 mg/kg @ 28 d (nonedible)5.719 mg/kg @ 28 d 

(non-edible)

43441127/

43441139

165-4

Pheny label/bluegill sunfish 

(Lepomis macrochirus)

0.692 mg/kg @ 21 d 

(edible)

0.631 mg/kg @ 28 d 

(edible)

43441127/

43441139

165-4

Pheny label/bluegill sunfish 

(Lepomis macrochirus)

Transformation Product 20

FANACS

Nacetyl-S-[2-[(4-fluorophenyl)(1-

methylethyl)amino]-2-oxoethyl]cysteine

Fish BCF

2.431 mg/kg @ 28 d (nonedible)2.431 mg/kg @ 28 d 

(non-edible)

43441127/

43441139

165-4

Pheny label/bluegill sunfish 

(Lepomis macrochirus)

0.326 mg/kg @ 21 d 

(edible)

0.260 mg/kg @ 28 d 

(edible)

43441127/

43441139

165-4

Pheny label/bluegill sunfish 

(Lepomis macrochirus)

28
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Transformation Product 21

Flufenacet GLU

Fish BCF

0.52 mg/kg @ 21 d (nonedible)0.467 mg/kg @ 28 d 

(non-edible)

43441127/

43441139

165-4

Pheny label/bluegill sunfish 

(Lepomis macrochirus)

Carbon dioxide Aerobic Soil Metabolism

50.9% @ 368 d 50.9% @ 368 d 43441135

162-1

Thiadiazole label/sandy loam

5.9% @ 365 d 5.9% @ 365 d 43441141

162-1

Phenyl label/sandy loam 

14.2% @ 120 d 14.2% @ 120 d 43850058

162-1

Phenyl label/loamy sand

23.8% @ 120 d 23.8% @ 120 d 43850058

162-1

Phenyl label/silt loam 

(Laacherhof)

12.0% @ 120 d 12.0% @ 120 d 43850058

162-1

Phenyl label/silt loam (Hofchen)

Anaerobic Soil Metabolism

1.8% @ 210 d 1.8% @ 210 d 43850059

162-2

Phenyl label/sandy loam

29
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Anaerobic Aquatic Metabolism

0.1% @ 91 d 0.1% @ 91 d 43850060

162-3

Phenyl label/pond water-sandy 

loam soil

1.4% @ 99 d 1.4% @ 99 d 43850061

162-3

Thiadiazole label/pond watersandy loam soil

Aerobic Aquatic Metabolism

3.4% @ 157 d 3.4% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA; entire 

system)

1.5% @ 157 d 1.5% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP; entire 

system)

15.3% @ 156 d 15.3% @ 156 d 45796112

162-4

Thiadiazole label/pond watersilty clay sediment (NESA; entire 

system)

15.0% @ 156 d 15.0% @ 156 d 45796112

162-4

Thiadiazole label/pond watersilty clay loam sediment (BRP; 

entire system)

Nonextracted residues Aerobic Soil Metabolism

17.7% @ 271 d 16.5% @ 365 d 43441141

162-1

Phenyl label/sandy loam

6.9% @ 270 d 6.5% @ 368 d 43441135

162-1

Thiadiazole label/sandy loam

30
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

24.4% @ 19 d 19.5% @ 88 d 43850066

162-1

Phenyl label/fine sandy loam

25.3% @ 88 d 25.3% @ 88 d 43850066

162-1

Phenyl label/sandy loam

42.3% @ 120 d 42.3% @ 120 d 43850058

162-1

Phenyl label/loamy sand

37.1% @ 120 d 37.1% @ 120 d 43850058

162-1

Phenyl label/silt loam 

(Laacherhof)

58.0% @ 120 d 58.0% @ 120 d 43850058

162-1

Phenyl label/silt loam (Hofchen)

Anaerobic Soil Metabolism

32.6% @ 210 d 32.6% @ 210 d 43850059

162-2

Phenyl label/sandy loam

Anaerobic Aquatic Metabolism

10.0% @ 63 d 6.0% @ 91 d 43850060

162-3

Phenyl label/pond water-sandy 

loam soil

0.6% @ 64-99 d 0.6% @ 99 d 43850061

162-3

Thiadiazole label/pond watersandy loam soil

31
Transformation Product Name and 

Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling 

interval (Interval)

Study and 

Guideline 

number

Comments

Aerobic Aquatic Metabolism

28.5% @ 157 d 28.5% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (NESA)

46.4% @ 157 d 46.4% @ 157 d 44580203

162-4

Phenyl label/pond water-silty clay 

loam sediment (BRP)

3.3% @ 55 d 2.2% @ 156 d 45796112

162-4

Thiadiazole label/pond watersilty clay sediment (NESA)

9.6% @ 100 d 7.5% @ 156 d 45796112

162-4

Thiadiazole label/pond watersilty clay loam sediment (BRP)

32
Table A-2. Thiadone as the Test Material transformation products.

Transformation Product

Name and Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling interval 

(Interval)

Study and 

Guideline 

number

Comments

Transformation Product 1

Propionic acid conjugate of 

thiadone

Soil Photolysis

irradiated- 6.1% @ 10 d

dark- 12.0% @ 7 d

irradiated- 2.9% @ 14 d

dark- 2.1% @ 14 d

45796108

161-3

Loamy sand soil

Aerobic Soil Metabolism

10.2% @ 2 d 0.1% @ 10 d 45796109

162-1

Loamy sand

7.0% @ 2 d 0.1% @ 10 d 45796109

162-1

Sandy loam

1.3% @ 1 d Not detected @ 14 d 45796109

162-1

Silt loam

Carbon Dioxide Soil Photolysis

irradiated- 57.8% @ 14 d

dark- 57.6% @ 14 d

irradiated- 57.8% @ 14 d

dark- 57.6% @ 14 d

45796108

161-3

Loamy sand soil

Aerobic Soil Metabolism

63.2% @ 10 d 63.2% @ 10 d 45796109

162-1

Loamy sand

82.1% @ 10 d 82.1% @ 10 d 45796109

162-1

Sandy loam

71.8% @ 14 d 71.8% @ 14 d 45796109

162-1

Silt loam

Anaerobic Aquatic Metabolism

1.9% @ 303 d 1.9 % @ 303 d 45796110

162-3

Water-silty clay sediment (entire system)

33
Transformation Product

Name and Structure

Maximum Percent of 

Applied Dose (Interval)

Percent of Applied Dose 

at final sampling interval 

(Interval)

Study and 

Guideline 

number

Comments

Aerobic Aquatic Metabolism

10.9% @ 160 d 10.9% @ 160 d 45796111

162-4

Water-silty clay sediment (entire system)

Nonextractable residues Aerobic Soil Metabolism

20.1% @ 7 d 19.5% @ 10 d 45796109

162-1

Loamy sand

8.4% @ 5 d 7.6% @ 10 d 45796109

162-1

Sandy loam

14.7% @ 7-14 d 14.7% @ 14 d 45796109

162-1

Silt loam

Anaerobic Aqautic Metabolism

3.0% @ 61 d 0.8 % @ 303 d 45796110

162-3

Water-silty clay sediment (entire system)

Aerobic Aquatic Metabolism

2.4% @ 160 d 2.4% @ 160 d 45796111

162-4

Water-silty clay sediment (entire system)

34
Appendix B – Surface Water Modeling

Figure A-1. Flufenacet SWCC output for IL Corn scenario.

Table 1. Estimated Environmental Concentrations (ppb) for Flufenacet_ILCorn.

Peak (1-in-10 yr) 27.7

4-day Avg (1-in-10 yr) 26.9

21-day Avg (1-in-10 yr) 24.6

60-day Avg (1-in-10 yr) 20.1

365-day Avg (1-in-10 yr) 7.16

Entire Simulation Mean 4.12

Table 2. Summary of Model Inputs for Flufenacet_ILCorn.

Scenario ILCornSTD

Cropped Area Fraction 1.0

Koc (ml/g) 434.4

Water Half-Life (days) @ 25 °C 77.1

Benthic Half-Life (days) @ 25 °C 492

Photolysis Half-Life (days) @ 45 

°Lat

0

Hydrolysis Half-Life (days) 0

Soil Half-Life (days) @ 25 °C 48.2

Foliar Half-Life (days) 0

Molecular Wt 363.6

Vapor Pressure (torr) 2.11e-7

Solubility (mg/l) 56

Table 3. Application Schedule for Flufenacet_ILCorn.

Date (Days 

Since 

Emergence)

Type Amount (kg/ha) Eff. Drift

-15 Ground 0.898 1.0 0.066

35
Figure 1. Yearly Peak Concentrations

36
Appendix C – Ground Water Modeling

Figure C-1. PRZM-GW output for WI Sands scenario with flufenacet.

Table 1. Groundwater Results for Flufenacet_WISands and the Wisconsin Corn - WI 

Central Sands Scenario.

Peak Concentration (ppb) 12.4

Post-Breakthrough Mean 

Concentration (ppb)

 11

Entire Simulation Mean 

Concentration (ppb)

 4.12

Average Breakthrough 

Time (days)

8188.552

Throughputs 1.338454

Table 2. Chemical Properties for Groundwater Modeling of Flufenacet_WISands.

Koc (ml/g) 434.4

Surface Soil Half Life (days) 48.2

Hydrolysis Half Life (days) 0

Diffusion Coefficint Air (cm2/day) 0.0

Henry's Constant 0.0

Enthalpy (kcal/mol) 0.0

Table 3. Pesticide application scheme used for Flufenacet_WISands. This application 

scheme was applied every year of the simulation.

Application Days 

Relative to 

Emergence Date 

(05/01)

Application Method Application Rate

(kg/ha)

-15 All pesticide placed at 5.08 cm 

below surface

0.898

37
Figure 1. Aquifer Breakthrough Curve for Flufenacet_WISands and the Wisconsin Corn -

WI Central Sands Scenario

38
Figure C-2. PRZM-GW output for WI Sands scenario with flufenacet thiadone.

Table 1. Groundwater Results for Thiadone and the Wisconsin Corn - WI Central Sands 

Scenario.

Peak Concentration (ppb) 0.0662

Post-Breakthrough Mean 

Concentration (ppb)

 0.0188

Entire Simulation Mean 

Concentration (ppb)

 0.0135

Average Breakthrough 

Time (days)

2953.866

Throughputs 3.710392

Table 2. Chemical Properties for Groundwater Modeling of Thiadone.

Koc (ml/g) 43.5

Surface Soil Half Life (days) 2.77

Hydrolysis Half Life (days) 0

Diffusion Coefficint Air (cm2/day) 0.0

Henry's Constant 0.0

Enthalpy (kcal/mol) 0.0

Table 3. Pesticide application scheme used for Thiadone. This application scheme was 

applied every year of the simulation.

Application Days 

Relative to 

Emergence Date 

(05/01)

Application Method Application Rate

(kg/ha)

-15 All pesticide placed at 5.08 cm 

below surface

0.02

39
Figure 1. Aquifer Breakthrough Curve for Thiadone and the Wisconsin Corn - WI Central 

Sands Scenario

40
Figure C-3. SCI-GROW output file for flufenacet and flufenacate thiadone.

 SCIGROW

VERSION 2.3

 ENVIRONMENTAL FATE AND EFFECTS DIVISION

 OFFICE OF PESTICIDE PROGRAMS

 U.S. ENVIRONMENTAL PROTECTION AGENCY

 SCREENING MODEL

 FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3

chemical:flufenacet

time is 2/ 1/2015 13:41:42

------------------------------------------------------------------------

 Application Number of Total Use Koc Soil Aerobic

 rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------

 0.802 1.0 0.802 4.35E+01 48.2

------------------------------------------------------------------------

groundwater screening cond (ppb) = 9.37E-01 

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

41