Test Material: Sulfentrazone 

MRID: 48958902 

Title: Keenan, D.J. and A. DePompei. 2012. [14C]Sulfentrazone: Aerobic 

Aquatic Sediment Metabolism. 

EPA PC Code: 129081 

OCSPP Guideline: 835.4300 

For CDM Smith: 

Primary Reviewer: Dana Worcester Signature: ~~ {.;)~· 

Date: 11/12/13 

Secondary Reviewer: Kathleen Ferguson Signature: 'i(~f' ~ 

Date: 11112/ 13 

QC/QA Manager: Joan Gaidos 

For the Environmental Protection 

Agency: 

Final Reviewer: Michael Barrett 

Signature: /J/. 

Date: 11/12/13 

Date: 9112/2014 
Sulfentrazone (PC 129081) MRID 48958902

Page 2 of 22

Aerobic Degradation of Sulfentrazone in Aquatic Systems

Report: MRID 48958902. Keenan, D.J. and A. DePompei. 2012. [14C]Sulfentrazone: 

Aerobic Aquatic Sediment Metabolism. Unpublished study performed by Ricerca 

Biosciences, LLC, Concord, Ohio; sponsored and submitted by FMC 

Corporation, Ewing, New Jersey. Ricerca Study No.: 028157. FMC Study No.: 

162E2211E1. FMC Report No.: PC-0781. Experiment started October 28, 2011 

and terminated February 13, 2012 (p. 18). Final report issued September 18, 

2012.

Document No.: MRID 48958902

Guideline: OCSPP 835.4300

Statements: The study was conducted according to USEPA Principles of Good Laboratory 

Practice (p. 3). Signed and dated Data Confidentiality, GLP, and Quality 

Assurance statements were provided (pp. 2-4). The authenticity of the study 

report is certified in the Quality Assurance Statement.

Classification: This study is classified as supplemental. Posttreatment redox potentials, 

dissolved oxygen content, and pH of the test systems were not reported. Limits of 

Detection and Quantitation were not reported. Additional details on data 

limitations that would be required to upgrade the study are provided in the 

“Study Deficiencies, Reviewer's Comments, and Data Needs” section.

PC Code: 129081

Reviewer: Michael R. Barrett

U.S. EPA Date: September 12, 2014

Executive Summary

The aerobic transformation of [phenyl14C]- and [carbonyl14C]-labeled sulfentrazone was studied

in a California pond water:silty clay loam sediment system (sediment pH 6.1, organic matter 5.1%) 

and a California canal water:sandy loam sediment system (sediment pH 6.0, organic matter 2.1%) 

for 100 days in a closed system in the dark at 20C. The systems were treated at 0.164-0.176 mg

a.i./L. It was unknown if aerobic conditions were maintained, since redox potentials were not 

reported. Microbial population determinations of untreated sediments indicated the systems were 

viable at study initiation and termination.

In the pond water:silty clay loam sediment system (combined labels), the overall mass balances 

were 94.7-110.0% of the applied. In the canal water:sandy loam sediment system (combined labels), 

the overall mass balances were 94.7-108.4% of the applied. There was some decline in recoveries 

during the experiments. 

Observed DT50 values, calculated half-lives, and information on transformation products are listed 

in Table 1. Rates and patterns of dissipation of sulfentrazone were comparable between the two 

sediments. 

In the pond water:silty clay loam sediment (both labels), residues in the water decreased from 98.5-

104.6% of the applied at time 0 to 49.9-58.6% at 100 days. Extractable soil residues increased from 

2.5-2.7% of the applied at day 0 to 42.0-53.1% at 70 days and were 41.7-43.8% at 100 days. 

Unextracted radioactivity increased from 1.6-2.8% of the applied at day 0 to 5.4-9.2% at 14 days 
Sulfentrazone (PC 129081) MRID 48958902

Page 3 of 22

and was 7.3-7.7% at 100 days. Total evolved 14CO2 totaled 0.1-0.3% of the applied at 100 days; 

volatile organics were 0.1%.

In the canal water:sandy loam sediment (both labels), residues in the water decreased from 99.0-

100.9% of the applied at time 0 to 60.0-60.9% at 100 days. Extractable soil residues increased from 

2.4-2.7% of the applied at day 0 to 33.1-37.4% at 70 days and were 31.9-36.0% at 100 days. 

Unextracted radioactivity increased from 1.7-3.2% of the applied at day 0 to 6.9-9.3% at 100 days.

Total evolved 14CO2 totaled 0.1-0.9% of the applied at 100 days; volatile organics were 0.2-0.9%.

Table 1. Results Synopsis: Aerobic Aquatic Metabolism of Sulfentrazone in the Total System

Total System

Observed 

DT50

(days)

Calculated 

Half-life 

(days)

1

Model 

Parameters and 

Statistics

Transformation Products Common Name

(maximum % of applied observed, 

associated interval)

Major Minor

California

Pond water:silty clay 

loam sediment (20oC, 

sediment pH 6.1)

>100 679

SFO

C0 = 100

k = 0.00102

Sc = 425

SSFO = 386

None

SCA (1.0% at 100 days)

HMS (1.2% at 100 days)

CO2 (0.3% at 100 days)

California 

Canal water:sandy

loam sediment 

system (20oC, 

sediment pH 6.0)

>100 612

SFO

C0 = 100

k = 0.00113

Sc = 202

SSFO = 185

None

SCA (1.3% at 100 days)

HMS (1.4% at 100 days)

CO2 (0.9% at 100 days)

1 Calculated half-lives and model parameters selected in accordance with NAFTA kinetics guidance (USEPA, 2012);

Simple First Order (SFO).

I. Materials and Methods

A. Materials

1. Test Material: [Phenyl-U14C]- and [carbonyl14C]- labeled sulfentrazone (p. 19, 

Appendix 6, pp. 139-140).

Phenyl

Specific activity: 22.9 mCi/mMol (p. 19, Appendix 6, 

p. 139)

Radiochemical purity: 98.3%

Chemical purity: Not reported

Lot No.: 54175-2-22
Sulfentrazone (PC 129081) MRID 48958902

Page 4 of 22

Carbonyl

Specific activity: 30.6 mCi/mMol (p. 20, Appendix 6, 

p. 140).

Radiochemical purity: 99.5%

Chemical purity: Not reported.

Lot No.: 54175-1-22

Solubility in water: Not reported

2. Reference Compounds: The following compounds were used in the analysis.

Table 2. Reference Compounds

Applicant’s Code Name

(synonyms) Chemical Name Purity(%) Lot No.

Sulfentrazone

N-[2,4-Dichloro-5-[4-difluoromethyl-4,5-dihydro3-methyl-5-oxo-1H-1,2,4-triazol-1-

yl]phenyl]methanesulfonamide

-- E9337:19

Sulfentrazone-3-carboxylic acid 

(SCA)

1-[2,4-Dichloro-5-[N(methylsulfonyl)aminophenyl]-4-difluoromethyl-4,5-dihydro-5-oxo-1H1,2,4-triazol-3-carboxylic acid

-- SU-4

3-Desmethyl sulfentrazone 

(DMS)

1-[2,4-Dichloro-5-(N-(methylsulfonyl)aminophenyl]-4-difluoromethyl-1H-1,2,4-triazol-5(4H)-

one

-- SU-24

3-Hydroxymethyl-sulfentrazone

(HMS)

1-[2,4-Dichloro-5-(N-(methylsulfonyl)aminophenyl]-4-difluoromethyl-3-hydroxy-methyl-1H1,2,4-triazol-5(4H)-one

-- SU-29

Methyl triazole 4-Difluoromethyl-5-methyl2,4-dihydro[1,2,4]-

triazole-3-one

-- SU-32

Data obtained from pp. 20-22 of the study report.

3. Water:Sediment: Water and sediment collection and characterization are summarized in Table 

3 and Tables 4a-4b, respectively.

Table 3. Water:Sediment Collection and Storage

Description Pond water:sediment Canal water:sediment

Geographic location California

Pesticide use history at the 

collection site Not reported.

Collection date Not reported, received October 10, 2011

Collection 

procedures

Water: In accordance with ISO 10381-6

Sediment: In accordance with ISO 10381-6

Storage conditions Stored in a dark incubator at 4 ± 2C ̊

Storage length Not reported, ca. 3 weeks based on date of receipt and experimental start date 

(October 28, 2011)

Preparation 

Water: Not reported.

Sediment: Wet sieved (2.0 mm).

Data obtained from pp. 18, 22-23 of the study report. 
Sulfentrazone (PC 129081) MRID 48958902

Page 5 of 22

Table 4a. Parameters for Characterization of Pond Water:Sediment Samples

Parameter

(unit)

Field Sampling/Post 

Handling

Stage of Test Procedure

Prior to Test During Test End of Test

Water

Temperature (oC) Not reported

pH Not reported

TOC (mg/L) 2.9

Microbial biomass: Not reported

O2 Not reported

Redox potential (Eh, mV) Not reported

Sediment

Sampling Depth Not reported

pH (1:1 sediment:water) 6.1

Soil Texture (USDA) Silty clay loam

Particle Size Distribution

16% sand

50% silt

34% clay

Organic matter (%) 5.1

CEC (meq/100 g) 15.5

Microbial biomass (μg/g) -- 484.6 17.4

Redox potential (Eh, mV) Not reported

Data obtained from p. 23; Table 1, p. 38; and Appendix 3, pp. 123-126 of the study report. Soil texture confirmed by the 

reviewer using USDA-NRCS technical support tools.

-- = Not reported.

Table 4b. Parameters for Characterization of Canal Water:Sediment Samples 

Parameter

(unit)

Field Sampling/Post

Handling

Stage of Test Procedure

Prior to Test During Test End of Test

Water

Temperature (oC) Not reported

pH Not reported

TOC (mg/L) 3.0

Microbial biomass Not reported

O2 Not reported

Redox potential (Eh, mV) Not reported

Sediment

Sampling Depth Not reported

pH (1:1 sediment:water) 6.0

Soil Texture (USDA) Sandy loam

Particle Size Distribution

60% sand

31% silt

9% clay

Organic matter (%) 2.1

CEC (meq/100 g) 6.8

Microbial biomass (μg/g) -- 55.8 34.9

Redox potential (Eh, mV) Not reported

Data obtained from p. 30; Table 2, p. 39; and Appendix 3, p.. 127-130 of the study report. Soil texture confirmed by the 

reviewer using USDA-NRCS technical support tools.
Sulfentrazone (PC 129081) MRID 48958902

Page 6 of 22

B. Study Design

1. Experimental Conditions: Table 5 summarizes the experimental conditions.

Table 5. Experimental Design

Experimental Design Pond water:sediment Canal water:sediment

Duration of the test 100 days

Water:

Type and size of filter used Not reported

Amount of sediment and water per treatment:

Water

Volume: ca. 178 mL

Depth: Water was added to a height of 10 cm.

Sediment Weight: ca. 65 g dry wt. ca. 70 g dry wt.

Depth: 2.5 cm.

Water/sediment ratio

Volume:Weight 2.7:1 (178 mL water:65 g dry wt. 

sediment).

2.5:1 (178 mL water:70 g dry wt. 

sediment).

Depth: 4:1

Application rates:

Nominal 0.139 μg a.i./mL

Actual Phenyl: 0.171 μg a.i./mL

Carbonyl: 0.164 μg a.i./mL

Phenyl: 0.176 μg a.i./mL

Carbonyl: 0.169 μg a.i./mL

Number of replicates:

Control, if used Sterile controls were not used.

Treated Duplicate samples per system were collected at each sampling interval.

Test apparatus:

Type/material/volume Nonsterile: Wide-mouth glass bottles (ca. 250 mL), each separately connected to a 

continuous flow-through volatiles trapping system.

Sterile: Sterile controls were not used.

Details of traps for CO2 and organic volatile, if 

any

Humidified air was pulled over the test system, then through one tube 

of ethylene glycol and two tubes of 1N NaOH.

If no traps were used, 

is the system closed?

Nonsterile: Volatile traps were used.

Sterile: Sterile controls were not used

Identity and final concentration (based on 

water volume) of co-solvent None, water

Test material application method:

Volume of the test solution used/treatment 1 mL (1000 L)/sample (application rate based on 175-180 mL water 

in sample)

Application method (i.e., mixed/not mixed) The test solution was applied to the water surface via glass pipette

Any indication of the test material adsorbing 

to the walls of the test apparatus? No

Microbial biomass/population of treated 

(units): Not determined in treated systems.

Water --

Sediment --

Experimental conditions:

Temperature: 20 ± 2°C, graphical data appears to show several deviations

Continuous darkness (yes/no) Yes

Other details (if any) The water:sediment systems were acclimated to test conditions for 9

days prior to treatment.

Data obtained from pp. 23-25; Table 3, p. 40; and Appendix 4, pp. 131-136 of the study report.
Sulfentrazone (PC 129081) MRID 48958902

Page 7 of 22

2. Sampling during Study Period: Table 6 summarizes sampling during the study period.

Table 6. Sampling during Study Period

Parameter Details

Sampling intervals 

(duration)

Nonsterile: 0, 14, 30, 45, 70, and 100 days posttreatment

Sterile controls: Sterile controls were not used.

Sampling method Duplicate samples were collected at each sampling interval.

Method of collection of CO2 and organic 

volatile compounds Respective volatile traps were collected at each sampling interval.

Sampling Intervals/Times

Temperature

Not reported

Redox potential in water layer

Dissolved oxygen in water layer

pH in water layer

Redox potential in sediment

pH in sediment Not determined.

Other details, if any Samples not analyzed immediately were stored at <-5 ̊C

Data obtained from pp. 25-27 of the study report.

3. Analytical Procedures:

Separation of the Water and Sediment: The water layer was separated from the sediment by 

decanting (p. 27).

Extraction/Clean Up/Concentration Methods: Water was analyzed directly by LSC and HPLC 

(p. 27).

Sediment was extracted once with acetonitrile and twice with acetonitrile:water (80:20, v:v) by 

shaking at room temperature (p. 28). Resulting extracts were analyzed for total radioactivity by 

LSC. The acetonitrile extract was concentrated under a stream of nitrogen and analyzed by HPLC; 

the acetonitrile:water extract was apparently not further analyzed.

Determination of Unextracted Residues: Extracted sediment was analyzed for total radioactivity 

by LSC following combustion (p. 28).

Determination of Volatile Residues: Aliquots of the trapping solutions were analyzed for total 

radioactivity using LSC (p. 25). The presence of CO2 was not confirmed.

Total Radioactivity Measurement: Total [

14C] residues were determined by summing the 

concentrations of residues measured in the water layer, sediment extracts, extracted sediment and 

volatiles trapping solutions (p. 30).

Derivatization Method: None reported.

Identification and Quantification of Parent Compound and Transformation Products: Water 

layer and acetonitrile:water sediment extract samples were analyzed by HPLC using a Luna C 18 
Sulfentrazone (PC 129081) MRID 48958902

Page 8 of 22

column eluted with a gradient mobile phase of (A) 0.01M ammonium acetate in water or water and 

(B) acetonitrile (p. 27). A second confirmatory method was not utilized.

Detection Limits (LOD, LOQ) for the Parent Compound and Transformation Products:

Limits of detection (LOD) and quantitation (LOQ) were not reported.

II. Results and Discussion

A. Data:

Study results, including total mass balances and distribution of radioactivity, are presented in 

Tables 7a and 7d. The incubation temperature was reported as 20 ± 2oC (p. 24).Graphical data 

appears to show deviations from the range (Appendix 4, pp. 131-132). Microbial population

determinations of untreated sediments indicated the systems were viable at study initiation and 

termination (Appendix 3, pp. 125-126, 129-130). Dissolved oxygen, redox potentials and pH results 

were not reported.

B. Mass Balance:

In the pond water:silty clay loam sediment system treated with the phenyl label, the overall mass 

balances range was 96.4-110.0% of the applied (Table 3, p. 41). In the pond water:silty clay loam 

sediment system treated with the carbonyl label, the overall mass balances range was 94.7-102.5% 

of the applied (Table 8, p. 43). 

In the canal water:sandy loam sediment system treated with the phenyl label, the overall mass 

balances range was 99.9-108.4% of the applied (Table 6, p. 42). In the canal water:sandy loam 

sediment system treated with the carbonyl label, the overall mass balances range was 94.7-104.5% 

of the applied (Table 10, p. 44). The recoveries met guideline requirements in both water:sediment 

systems.

C. Bound and Extractable Residues:

In the pond water:silty clay loam sediment treated with the phenyl label, extractable radioactivity 

increased from 2.7% of the applied at day 0 to 53.1% at 70 days and was 41.7% at 100 days (Table 

4, p. 41). Unextracted radioactivity increased from 2.8% of the applied at day 0 to 9.2% at 14 days 

and was 7.3% at 100 days.

In the pond water:silty clay loam sediment treated with the carbonyl label, extractable radioactivity 

increased from 2.5% of the applied at day 0 to 43.8% at 100 days (Table 8, p. 43). Unextracted 

radioactivity increased from 1.6% of the applied at day 0 to 7.7% at 100 days.

In the canal water:sandy loam sediment treated with the phenyl label, extractable radioactivity 

increased from 2.7% of the applied at day 0 to 37.4% at 70 days and was 36.0% at 100 days (Table 

6, p. 42). Unextracted radioactivity increased from 3.2% of the applied at day 0 to 9.3% at 100 days.
Sulfentrazone (PC 129081) MRID 48958902

Page 9 of 22

In the pond water:sandy loam sediment treated with the carbonyl label, extractable radioactivity 

increased from 2.4% of the applied at day 0 to 33.1% at 70 days and was 31.9% at 100 days (Table 

10, p. 44). Unextracted radioactivity increased from 1.7% of the applied at day 0 to 6.9% at 100 

days.

D. Volatilization:

Evolved 14CO2 totaled a maximum 0.2-0.3% in the pond water:silty clay loam sediment systems 

(Table 4, p. 41; Table 8, p. 43). Volatile organics were 0.1%. 

Evolved 14CO2 totaled a maximum 0.1-0.9% in the canal water:sandy loam sediment systems 

(Table 6, p. 42; Table 10, p. 44). Volatile organics were 0.2-0.9%.
Sulfentrazone (PC 129081) MRID 48958902

Page 10 of 22

Table 7a. Transformation of [phenyl14C]sulfentrazone, expressed as a percentage of applied radioactivity in aerobic water:silty clay 

loam sediment

Sampling Interval 

(days) 0 14 30 45 70 100

Replicate 1 2 1 2 1 2 1 2 1 2 1 2

Sulfentrazone 107.2 106.5 100.0 97.9 92.9 102.3 94.3 97.3 97.3 94.6 93.5 99.6

SCA 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

HMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

DMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Extractables 2.7 1.9 25.8 25.4 32.9 36.1 44.2 39.1 41.3 53.1 41.7 41.0

Water 104.5 104.6 74.2 72.5 60.0 66.2 50.2 58.2 56.4 42.4 51.9 58.6

Unextracted residues 2.8 2.8 8.8 9.2 3.3 4.7 5.8 4.7 5.5 7.5 7.3 6.9

CO2 na na 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.3 0.3

Volatile organics na na 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1

Mass balance 110.0 109.2 108.9 107.1 96.4 107.1 100.4 102.3 103.6 103.3 101.3 106.8

Data obtained from Table 4, p. 41 and Table 28, p. 53 of the study report.

na = Not applicable

Table 7b. Transformation of [carbonyl14C]sulfentrazone, expressed as a percentage of applied radioactivity in aerobic water:silty 

clay loam sediment

Sampling Interval 

(days) 0 14 30 45 70 100

Replicate 1 2 1 2 1 2 1 2 1 2 1 2

Sulfentrazone 101.0 99.5 95.9 96.1 92.8 90.9 91.7 92.8 91.1 93.9 86.1 97.0

Methyl triazole 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

SCA 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 1.5

HMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.8 1.2

DMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Extractables 2.5 2.4 24.5 26.0 34.2 34.9 39.7 37.4 42.0 41.0 43.8 38.7

Water 98.5 97.1 71.4 70.1 58.7 56.1 52.0 55.5 49.4 52.9 44.1 49.9

Unextracted residues 1.5 1.6 5.2 5.4 4.4 4.0 5.3 4.7 5.3 6.2 6.7 7.7

CO2 na na 0.1 0.1 0.2 0.2 0.1 0.1 0.1 0.1 0.1 0.1

Volatile organics na na 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1

Mass balance 102.5 101.1 101.2 101.6 97.4 95.1 97.1 97.6 96.9 100.3 94.7 96.5

Data obtained from Table 8, p. 43 and Table 32, p. 55 of the study report.

na = Not applicable
Sulfentrazone (PC 129081) MRID 48958902

Page 11 of 22

Table 7c. Transformation of [phenyl14C]sulfentrazone, expressed as a percentage of applied radioactivity in aerobic water:sandy 

loam sediment.

Sampling Interval 

(days) 0 14 30 45 70 100

Replicate 1 2 1 2 1 2 1 2 1 2 1 2

Sulfentrazone 102.1 101.0 100.5 101.1 93.7 95.6 96.4 94.5 94.5 96.8 94.2 90.7

SCA 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

HMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

DMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Extractables 2.7 2.0 20.6 22.4 26.6 31.3 36.2 28.8 33.5 37.4 36.0 29.8

Water 99.3 99.0 79.9 78.7 70.5 65.7 60.2 65.7 61.4 59.7 58.2 60.9

Unextracted residues 3.2 2.2 7.8 6.7 3.0 5.6 6.2 4.8 5.9 6.6 9.1 9.3

CO2 na na 0.2 0.2 0.3 0.3 0.5 0.5 0.5 0.5 0.9 0.9

Volatile organics na na 0.0 0.0 0.0 0.0 0.1 0.1 0.2 0.2 0.9 0.9

Mass balance 105.3 103.2 108.4 108.1 100.5 102.9 103.1 99.9 101.5 104.5 105.1 101.8

Data obtained from Table 6, p. 42 and Table 30, p. 54 of the study report.

na = Not applicable
Sulfentrazone (PC 129081) MRID 48958902

Page 12 of 22

Table 7d. Transformation of [carbonyl14C]sulfentrazone, expressed as a percentage of applied radioactivity in aerobic water:sandy 

loam sediment.

Sampling Interval 

(days) 0 14 30 45 70 100

Replicate 1 2 1 2 1 2 1 2 1 2 1 2

Sulfentrazone 102.0 103.0 96.8 94.9 92.1 93.8 92.4 91.1 93.6 93.3 84.8 87.3

Methyl triazole 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

SCA 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.3 1.0

HMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.4 1.2

DMS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Extractables 2.4 2.1 18.8 21.0 25.8 26.9 32.1 29.8 33.1 31.5 31.9 29.5

Water 99.6 100.9 78.0 73.9 66.3 66.9 60.3 61.3 60.8 62.0 55.6 60.0

Unextracted residues 1.7 1.5 5.1 4.5 3.8 3.6 4.8 4.8 6.6 5.3 6.9 6.0

CO2 na na 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Volatile organics na na 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.2 0.2

Mass balance 103.7 104.5 102.0 99.5 95.9 97.4 97.3 95.9 100.6 98.9 94.7 95.8

Data obtained from Table 10, p. 44 and Table 34, p. 56 of the study report.

na = Not applicable
Sulfentrazone (PC 129081) MRID 48958902

Page 13 of 22

E. Transformation of Parent Compound: Transformation kinetics of the parent compound 

(combined labels) in the total systems are summarized in the following Figure. Transformation 

product information summarized in Table 8.

Using first-order linear regression, the study authors determined a half-lives for each label of each 

sediment. In the pond water:silty loam sediment system, the half-lives were 897 and 559 days for 

the phenyl label and carbonyl label, respectively (p. 35). In the canal water:sandy loam sediment 

system, the half-lives were 809 and 500 days for the phenyl label and carbonyl label, respectively 

(p. 35). The reviewer calculated system half-lives were 679 days for the pond system and 612 days 

for the canal system. 

Transformation Kinetics of Sulfentrazone 
Sulfentrazone (PC 129081) MRID 48958902

Page 14 of 22

Table 8. Transformation Products of Sulfentrazone in Total Aquatic Systems

System Transformation 

product(s)

Maximum 

% AR 

Observed

Associated 

Interval 

(days)

Final % AR 

Observed

Final Interval 

(days)

California pond water:silty 

clay loam sediment (20oC, 

sediment pH 6.1)

SCA (carbonyl) 1.0 100 1.0

100

HMS (carbonyl) 1.2 100 1.2

California canal 

water:sandy loam 

sediment system (20oC, 

sediment pH 6.0)

SCA (carbonyl) 1.3 100 1.3

100

HMS (carbonyl) 1.4 100 1.4

1 Water and sediment pH obtained from Tables 28-34, pp. 53-56 of the study report.

Aerobic Aquatic Degradation Pathway. A pathway was not provided by the study author. 

Sulfentrazone was relatively stable (DT50 ca. 20-22 months) with formation of very minor 

transformation products and some limited binding to the sediment.

III. Study Deficiencies, Reviewer's Comments, and Data Needs

1. The study authors did not report posttreatment pH, DO and redox potentials. Although the study

protocol states that these would be measured (Appendix 5, p. 138) and a protocol deviation (p. 

37) suggests that these were measured at all but the final sampling interval for the pond system, 

no methodology is provided and no data are reported. It is therefore uncertain whether aerobic 

conditions were maintained in the water:sediment systems.
Sulfentrazone (PC 129081) MRID 48958902

Page 15 of 22

2. The pesticide use histories for the source sites for the sediments and waters were not reported. 

The sediments and waters were not analyzed for pesticides to establish that they were not 

contaminated prior to treatment.

3. Limits of Detection (LOD) and Quantitation (LOQ) for sulfentrazone and its transformation 

products were not reported.

4. Lengths and conditions of storage of sediments and associated waters prior to shipment to the 

test facility were not reported. Other than temperature (4oC) and access to air, conditions of

storage of sediments and associated waters at the test facility prior to preparation of 

water:sediment systems for pretreatment acclimation were not reported (pp. 22-23). Current 

OCSPP guidelines specify if storage is necessary, sediment and water should be sieved and 

stored together, water-logged (6-10 cm water layer), in the dark, at 4 ± 2°C for a maximum of 4 

weeks, with free access of air (open containers). It was not reported if the water was sieved.

5. The incubation temperature was 20 ± 2C, which is more variable than specified by guidelines 

(p. 25). The maximum and minimum temperatures were not reported. Data was provided 

graphically. In addition, graphs were difficult to read.

6. The study authors did not relate the application rate to a field use rate.

The following are required to potentially upgrade this study from “supplemental” to “acceptable” 

status:

1. Confirmation is needed of whether aerobic conditions were maintained in the water:sediment systems. 

The study authors did not report post-treatment pH, dissolved oxygen and redox potentials. 

2. Control sample analytical results for sulfentrazone residues need to be reported to determine whether 

background levels of sulfentrazone or degradates may have been present in the test system before 

treatment. The pesticide use histories associated with the source sediment / water source material should 

be reported. 

3. Collection details, including geographic location of the source sites, should be reported.

The study authors reported that the sediments were collected and managed in accordance with ISO 

10381-6 (p. 23). 

4. Limits of Detection (LOD) and Quantitation (LOQ) for sulfentrazone and its transformation products 

were not reported.

5. Details of the lengths and conditions of storage of sediments and associated waters prior to shipment to 

the test facility should be reported. Other than temperature (4oC) and access to air, conditions of storage 

of sediments and associated waters at the test facility prior to preparation of water:sediment systems for 

pretreatment acclimation were not reported (pp. 22-23). Current OCSPP guidelines specify if storage is 

necessary, sediment and water should be sieved and stored together, water-logged (6-10 cm water layer), 

in the dark, at 4 ± 2°C for a maximum of 4 weeks, with free access of air (open containers). It was not 

reported if the sediment was sieved.
Sulfentrazone (PC 129081) MRID 48958902

Page 16 of 22

6. A more detailed accounting of temperature of the incubated soil:sediment mixture during the study is 

needed. The incuba

by guidelines (p. 25). Daily temperature ranges should be reported numerically (the included graphs were 

difficult to read).

7. The application rate of the test substance should be related to a field use rate equivalent.

IV. References

1. U.S. Environmental Protection Agency. 2012. NAFTA Guidance for Evaluating and Calculating 

Degradation Kinetics in Environmental Media.

2. U.S. Environmental Protection Agency. 2008. Fate, Transport and Transformation Test -

Guidelines, OPPTS 835.4300, Aerobic Aquatic Metabolism. Office of Prevention, Pesticides 

and Toxic Substances, Washington, DC. EPA 712-C-08-018.
Sulfentrazone (PC 129081) MRID 48958902

Page 17 of 22

DER ATTACHMENT 1. Sulfentrazone and Its Environmental Transformation Products. A

Code Name/ Synonym Chemical Name Chemical Structure Study 

Type MRID Maximum %AR (day) Final %AR (study length)

PARENT

Sulfentrazone IUPAC: 2′,4′-Dichloro-5′-(4-

difluoromethyl-4,5-dihydro-3-

methyl-5-oxo-1H-1,2,4-triazol1-yl)methanesulfonanilide

CAS: N-[2,4-dichloro-5-[4-

(difluoromethyl)-4,5-dihydro-3-

methyl-5-oxo-1H-1,2,4-triazol1-yl]phenyl]methanesulfonamide

CAS No.: 122836-35-5

Formula: C11H10Cl2F2N4O3S

MW: 387.1 g/mol

SMILES: 

CLc1cc(CL)c(NS(=O)(=O)C)cc

1N2N=C(C)N(C(F)F)C2(=O)

835.4300

Aerobic 

aquatic 

metabolism

48958902

Pond 

water/silty 

clay loam

107.2% (0 d) 99.6% (100 d)

Canal 

water/sandy 

loam

102.1% (0 d) 94.2% (100 d)

MAJOR (>10%) TRANSFORMATION PRODUCTS

No major transformation products were identified.

MINOR (<10%) TRANSFORMATION PRODUCTS

Sulfentrazone 3-

carboxylic acid (SCA)

IUPAC: 1-(2,4-Dichloro-5-(N-

(methylsulfonyl)amino)-pheny]-

4-difluoromethyl-4,5-dihydro-5-

oxo-1H-1,2,4-triazol-3-

carboxylic acid

CAS: N-[2,4-dichloro-5-[4-

(difluoromethyl)-4,5-dihydro-5-

oxo-1H-1,2,4-triazol-1-

yl]phenyl]methanesulfonamido3-carboxylic acid

CAS No.: 134391-01-08

Formula: C11H8Cl2F2N4O5S

MW: 417.18 g/mol

835.4300

Aerobic 

aquatic 

metabolism

48958902

Pond 

water/silty 

clay loam

1.0% (100 d) 1.0% (100 d)

Canal 

water/sandy 

loam

1.3% (100 d) 1.3% (100 d)
Sulfentrazone (PC 129081) MRID 48958902

Page 18 of 22

Code Name/ Synonym Chemical Name Chemical Structure Study 

Type MRID Maximum %AR (day) Final %AR (study length)

SMILES: 

CS(=O)(=O)Nc1cc(c(cc1Cl)Cl)n

2c(=O)n(c(n2)C(=O)O)C(F)F

3-Hydroxymethylsulfentrazone (HMS)

IUPAC: 1-(2,4-Dichloro-5-(N-

(methylsulfonyl)amino)-pheny]-

4-difluoromethyl-3-hydroxymethyl-1H-1,2,4-triazol-5(4H)-

one

CAS No.: 134390-99-1

Formula: C11H10Cl2F2N4O4S

MW: 403.19 g/mol

SMILES: 

CS(=O)(=O)Nc1cc(c(cc1Cl)Cl)n

2c(=O)n(c(n2)CO)C(F)F

835.4300

Aerobic 

aquatic 

metabolism

48958902

Pond 

water/silty 

clay loam

1.2% (100 d) 1.2% (100 d)

Canal 

water/sandy 

loam

1.4% (100 d) 1.4% (100 d)

Carbon dioxide IUPAC: Carbon dioxide

Formula: CO2

MW: 44 g/mol

SMILES: C(=O)=O

835.4300

Aerobic 

aquatic 

metabolism

Pond 

water/silty 

clay loam

0.3% (100 d) 0.3% (100 d)

Canal 

water/sandy 

loam

0.9% (100 d) 0.9% (100 d)

REFERENCE COMPOUNDS NOT IDENTIFIED

3-Desmethyl 

sulfentrazone (DMS)

IUPAC: 1-(2,4-Dichloro-5-(N-

(methylsulfonyl)amino)-pheny]-

4-difluoromethyl-1H-1,2,4-

triazol-5(4H)-one

CAS: N-[2,4-dichloro-5-[4-

(difluoromethyl)-4,5-dihydro-5-

oxo-1,2,4-triazol-1-

yl]phenyl]methanesulfonamide

CAS No.: 134391-02-09

Formula: C10H8Cl2F2N4O3S

MW: 373.17 g/mol

SMILES: 

CS(=O)(=O)Nc1cc(c(cc1Cl)Cl)n

835.4300

Aerobic 

aquatic 

metabolism

48958902 NA NA
Sulfentrazone (PC 129081) MRID 48958902

Page 19 of 22

Code Name/ Synonym Chemical Name Chemical Structure Study 

Type MRID Maximum %AR (day) Final %AR (study length)

2c(=O)n(cn2)C(F)F

Methyl triazole IUPAC: 4-Difluoromethyl-5-

methyl-2,4-

dihydro[1,2,4]triazole-3-one

Formula: C4H5F2N3O

MW: 149.1 g/mol

SMILES: 

Cc1n[nH]c(=O)n1C(F)F

835.4300

Aerobic 

aquatic 

metabolism

48958902 NA NA

A AR means “applied radioactivity”. MW means “molecular weight”. NA means “not applicable”. 
Sulfentrazone (PC 129081) MRID 48958902

Page 20 of 22

Attachment 2: Statistics Spreadsheets and Graphs
Sulfentrazone (PC 129081) MRID 48958902

Page 21 of 22

Attachment 3: Calculations

Calculations were performed by the reviewer using R software, and the following equations. 

Single First-Order (SFO) Model

(eq. 1)

where, 

Ct = concentration at time t (%)

C0 = initial concentration (%)

e = Euler’s number (-)

k = SFO rate constant of decline (d-1)

t = time (d)

The SFO equation is solved with R kinetics software by adjusting C0 and k to minimize the 

objective function (SSFO) shown in equation 9.

DT50 = natural log (2)/k (eq. 2)

DT90 = ln (10)/k (eq. 3)

Indeterminate Order Rate Equation (IORE) Model

(eq. 4)

where, 

N = order of decline rate (-)

kIORE = IORE rate constant of decline (d-1)

This equation is solved with R kinetics software by adjusting C0, kIORE, and N to minimize the 

objective function for IORE (SIORE) (See equation 9). Half-lives for the IORE model are 

calculated using equation 5, which represents a first-order half-life that passes through the DT90 of 

the IORE model. (Traditional DT50 and DT90 values for the IORE model can be calculated using

equations 6 and 7.)

(eq. 5)

DT50 = 

k(N -1)

(C /2) -C

(1-N)

0

(1-N)

0

(eq. 6)

DT90 = 

k(N -1)

(C /10) -C

(1-N)

0

(1-N)

0

(eq. 7)
Sulfentrazone (PC 129081) MRID 48958902

Page 22 of 22

Double First-Order in Parallel (DFOP) Model

(eq. 8)

where,

g = the fraction of C0 applied to compartment 1 (-)

k1 = rate constant for compartment 1 (d-1)

k2 = rate constant for compartment 2 (d-1)

If C0 x g is set equal to a and C0(1-g) is set equal to c, then the equation can be solved with R 

kinetics software for a, c, k1, and k2 by minimizing the objective function (SDFOP) as described in 

equation 9.

DT50 and DT90 values can be calculated using equations 2 and 3, with k1 or k2 in place of k.

Objective Function: SFO, IORE, and DFOP are solved by minimizing the objective function (SSFO, 

SIORE, or SDFOP).

(eq. 9)

where, 

SSFO , SIORE, or SDFOP = objective function of kinetics model fit (%2)

n = number of data points (-)

Cmodel,t = modeled value at time corresponding to Cd,t (%)

Cd,t = experimental concentration at time t (%)

Critical Value to Determine Whether SFO is an Adequate Kinetics Model

If SSFO is less than SC, the SFO model is adequate to describe kinetics. If not, the faster of tIORE or 

the DFOP DT50 for compartment 2 should be used.

(eq. 10)

where,

Sc = the critical value that defines the confidence contours (%2)

p = number of parameters (3 in this case)

α = the confidence level (0.50 in this case)

F(α, p, n-p) = F distribution with α level of confidence and degrees of freedom p and n-p