### Test Material: Chlorimuron ethyl

MRID: 49526702

Title: Aerobic Aquatic Metabolism of Chlorimuron Ethyl [ 14 

### C] DPX

- F6025 in

Two Water

- Sediment Systems

EPA PC Code: 128901

OCSPP Guideline: 835.4300

For CDM Smith

Primary Reviewer: Kathl een Ferguson Signature:

Date: 3/11/15

Secondary Reviewer: Mary Samuel Signature:

Date: 3/11/15

QC/QA Manager: Joan Gaidos Signature:

Date: 3/11/15Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 2 of 21 

### Aerobic degradation of Chlorimuron ethyl in aquatic systems

R eport: MRID 49526702

. Ponte, V. 2014. Aerobic Aquatic Metabolism of Chlorimuron Ethyl [ 14 

### C] DPX

- F6025 in Two Water

- Sediment Systems. Unpublished study performed by PTRL West, Hercules, California ; sponsored and submitted by E.I. du Pont de Nemours and Comp any, Wilmington, Delaware. Sponsor Study No.:

DuPont

- 38491. PTRL West Project No.: 2551W. Experiment started June 16,

2014 , and completed November 4, 2014 (p. 6 ). Final report issued December 8

, 2014.

Document No.: MRID 49526702

Guideline: OPPTS 835.4300

Statements: The study was conducted according to USEPA GLP standards (p. 3). Signed and dated Data Confidentiality, GLP, Quality Assurance , and Certification of Authenticity statements were provided (pp. 2

- 5 ).

Classification: This study is classified Su pplemental

. The pesticide use history at the test sites was not reported, and it was not confirmed that the soils were pesticide

- free prior

to use.

PC Code: 128901

Reviewer: Richard Shamblen, Biologist

U.S. EPA Date: October 30, 2015

Executive Summary

The aerobic transformation of [phenyl

- U

14 

### C ]

- and [pyrimidine

- 2

- 14 

### C]

- labeled chlorimuron ethyl
(DPX

- F6025) was studied in a water:clay loam sediment system (Goose River; water pH 8.3, sediment pH 8.0 and organic carbon 2.4%) from North Dakota and a water:sand sediment system (Choptank River; water pH 6.9, sediment pH 6.7 and organic carbon 0.72%) from Maryland in
closed systems treated at 0.16

- 0.18 μ g/mL and incubated in the dark at 20 ° C for 100 days. Single samples (one entire fla sk) of each label treatment/system were collected at each sampling interval. In the water column of the water:clay loam sediment systems following treatment, standard redox potentials, oxygen saturation and pH were +202.3 to +465.3 mV, 4.16

- 8.70 ppm and 5. 98

- 7.93, respectively, with redox potentials and pH in the sediment of +78.3 to +448.3 mV and 6.13

- 7.53, respectively. In the water column of the water:sand sediment systems following treatment, standard redox potentials, oxygen saturation and pH were +243 .3 to +467.3 mV, 2.45

- 8.20 ppm and 5.73

- 8.29, respectively, with redox potentials and pH in the sediment of +39.3 to +474.3 mV and 5.65

- 7.57, respectively. In both test systems, the water layer was generally oxic and the sediment varied

from oxic to suboxi c with no clear pattern during the experiment. Both test systems were viable throughout the experiment.

In the water:clay loam sediment system, recoveries averaged 97.3 ± 1.8 % (sample range 9 5.8

- 100.7%) of the applied for samples treated with the phenyl l abel and 97.1 ± 1.7 % ( 95.1

- 99.8 %) for samples treated with the pyrimidine label. Recoveries were within guideline criteria (>90%

- <110%). In the water column, chlorimuron ethyl decreased from a maximum of 98.5 % of the applied at time 0 to 11.6 % at 100 day s posttreatment. In the sediment, chlorimuron ethyl was a

maximum of 29.4 % of the applied at 62 day s posttreatment and decreased to 4.8% at 100 days.Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 3 of 21 

### In the water:sand sediment system, recoveries averaged 96.5 ± 3.7 % (sample range 91.0

- 103.9 %) of
the appl ied for samples treated with the phenyl label and 95.3 ± 2.0 % ( 91.7

- 97.9 %) for samples treated with the pyrimidine label. Recoveries were within guideline criteria (>90%

- <110%). In the water column, chlorimuron ethyl decreased from a maximum of 97.0 % of the applied at time 0 to 5.0% in the phenyl treatment and 26.2% in the pyrimidine treatment at 100 days posttreatment. In the sediment, chlorimuron ethyl was a maximum of 10.1 % of the applied at 79 day s posttreatment

and decreased to 8.3% at 100 days.

Obs erved DT 50 

### values, calculated half

- lives, and information on transformation products are listed

in Table 1 . Chlorimuron ethyl dissipated with a DFOP Slow t 1/2 

### of 50.8 days in the water:clay loam sediment system. The SFO half

- life in the water:sand system was 59.8 days. Product profiles were comparable between the two systems. Six transformation products were identified.

In the clay loam sediments, extractable radioactivity increased from 4.1% of the applied at time 0 to a maximum of 40.9% at 62 days pos ttreatment and was 36.5% at 100 days. Unextracted radioactivity increased from 0. 3 % at time 0 to a maximum of 8.1 % at 10 0 days. 14 

### CO 2 

### was 0.0% during the experiment , and o rganic volatiles totaled a maximum of 1.1% at 100 days

.

In the sand sediments, extr actable radioactivity increased from 2.3 % of the applied at time 0 to a

maximum of 28.1% at 79 days posttreatment and was 26.8 % at 10 0 days. Unextracted radioactivity

increased from 0.0% at time 0 to a maximum of 1.1 % at 62 and 10 0 days

. 14 

### CO 2 

### was 0.5

- 0.7% at

79

- 100 days, and o rganic volatiles were 0.0% during the experiment.

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

Total System Observed

DT 50 (days) Calculated

Half

- life (days) 1 Model

Parameters and

Sta tistics 1 Transformation Products Common Name
(maximum % AR , associated interval) B,C

Major Minor

Goose River, North

Dakota USA Water:clay loam

sediment

(20 ° C, water pH 8.3, sediment pH 8.0) 28

- 62 Slow t 1/2 = 50.8

DFPO C 0 = 98.2

f = 0.192

k 0 = 0.136

k 1 = 0.0136 IN

- L8330 ( 66.6 %, 1 00 days) IN

- B4450 ( 1.0 %, 28 days)

IN

- 00581 ( 6.5 %, 100 days)

IN

- B7497 (2. 9 %, 6 2 days)

IN

- N6186 ( 2.9 %, 7 days)

IN

- H1427 (2.0%, 100

days)

Choptank River, Maryland, USA

Water: sand sediment

(20 ° C, water pH 6. 9

, sediment pH 6. 7 ) 28

- 79 59.8

SFO C 0 = 102

k = 0.0116

S C = 1.53e+03

S SFO = 1.67e+03 IN

- B4450 ( 39.8 %, 100 days)

IN

- L8330 ( 29.2 %, 79

days)

IN

- 00581 ( 32.1 %, 100

days)

IN

- N6186 ( 33.0 %, 100

days) IN

- B7497 ( 3.2 %, 79

- 100 days)

IN

- H1427 ( 4 .0%, 79 days)

CO 2 ( 0.7 %, 79 days)

1 Calcula ted half

- lives and model parameters in accordance with NAFTA kinetics guidance (USEPA, 2012); Double
First Order in Parallel (DFOP)

, Single First Order (SFO).

B AR means “applied radioactivity”

. C IN

- B4450, IN

- 00581, and IN

- B7497 are products of the phenyl moiety only. IN

- N6186 and IN

- H1427 are products

of the pyrimidine moiety only.Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 4 of 21 

### I. Materials And Methods

A. Materials:

1. Test Material [ Phenyl

- U

14 

### C ]

- and [pyrimidine

- 2

- 14 

### C]

- labeled chlorimuron ethyl ( p

. 19; Figure 1, p. 61 )

Phenyl label

Speci fic activity: 43.5 μ Ci/mg; 1.61 MBq/mg

Radiochemical purity: 97.6%

Chemical purity: Not reported

Lot No.: CFQ41767

Pyrimidine label

Specific activity: 47.9 μ Ci/mg; 1.77 MBq/mg

Radiochemical purity: 99.9%

Chemical purity: Not reported

Lot No.: CFQ41768

Solubility in water: 8.55 g/L in HPLC water (p. 19)

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

Table 2. Reference Compounds

.

Applicant’s Code Name Chemical Name Purity (%) Lot No.

Chlorimuron ethyl (DPX

- F6025)

-- 98.8 E62740

- 69

IN

- L8330

-- 99.1 E108786

- 91B

IN

- 00581

-- 99.9 03111DD

IN

- N6186

-- 99.7 E43079

- 021A

IN

- H1427

-- 95.7 AG0135

- 104

IN

- B4450

-- 99.6 004

IN

- B7497

-- 99.7 E118288

- 56

IN

- V9662

-- 99.4 E118288

- 74

Data obtained from p. 20 and Figure 1, pp. 62

- 63, of the study report.

-- = No information.



### 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 Goose River Choptank River

Geographic location Grand Forks County, North

Dakota Denton, Maryland

Site description Goose River Choptank River, tidal impact

Pesticide use history at the coll ection site Not reported

Collection date May 12, 2014 May 13, 2014Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 5 of 21 Description Goose River Choptank River

Collection procedures Water: Sediment auger Clear plastic container Sediment:

Storage conditions Water: Stored refrigerated ( ca

. 4 ° C) in t he dark Sediment:

Storage length 17 days 19 days

Preparation Water: Sieved ( ca

. 2

- mm mesh )

Sediment: Sieved ( ca

. 2

- mm mesh)

Data obtained from p p. 21

- 22 and Appendix 1, p p . 1 42

- 143, in the study report.



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

– Goose River.

Parameter (unit) Field Sampling/Post Handling Stage of Test Procedure

Prior to Test 1 During Test 2 End of Test 3

Water
Temperature ( oC)

-- pH 8.3 6.03, 7.02 5.98, 6 .55 6.0, 6.1
Hardness (mg/L as CaCO 3 ) 584

TOC ( μ g/g)

-- 272 10.89

O 2 Content ( ppm )

-- 6.70, 7.04 7.26, 7.54 7.90, 8.70
Standard redox potential (mV) +369.3, +398.3 +356.3, +371.3 +202.3, +223.3

Sediment
Sampling Depth 0

- 5 cm
pH 1:1 in water 8.0 6.24, 6.66 6.43, 7.05 6.13, 6.33
Soil Texture (USDA) Clay loam

Particle Size

Distribution
(%) Sand 30

Silt 42
Clay 28
Organic matter (%) 4.1
Organic carbon (%) 2.4
CEC (meq/100 g) 18.8

Microbial biomass ( μ g C/g sediment)

-- 383 125
Standard redox potential (mV) +373.3, +392.3 +258.3, +281.3 +204.3, +222.3
Data obtained from p. 32; Table 1, pp. 42

- 43; Table 4, p. 49 ; and Appendix 1, p. 142, in the study report. USDA sediment texture confirmed determined by the reviewe r using USDA

- NRCS technical support tools.

-- = not reported 1 Post acclimation (Day 0) 2 Day 62 3 Day 100



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

– Choptank River.

Parameter (unit) Field Sampling/Post Handling Stage of Test P rocedure

Prior to Test 1 During Test 2 End of Test 3

Water
Temperature ( oC)

-- pH 6.9 6.89, 7.13 6.85, 7.35 6.31, 6.58
Hardness (mg/L as CaCO 3 ) 39

TOC ( μ g/g)

-- 287 15.67

O 2 Content ( ppm )

-- 4.73, 5.25 7.63, 7.64 7.82, 8.20
Standard redox pot ential (mV) +309.3, +379.3 +338.3, +350.3 +243.3, +265.3

Sediment
Sampling Depth 5

- 10 cm
pH 1:1 in water 6.7 6.67, 6.84 6.20, 7.04 5.65, 6.22Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 6 of 21 Parameter (unit) Field Sampling/Post Handling Stage of Test P rocedure

Prior to Test 1 During Test 2 End of Test 3

Soil Texture (USDA) Sand

Particle Size

Distribution
(%) Sand 96

Silt 3
Clay 1
Organic m atter (%) 1.2
Organic carbon (%) 0.72
CEC (meq/100 g) 3.2

Microbial biomass ( μ g C/g sediment)

-- 278 58
Standard redox potential (mV) +114.3, +141.3 +333.3, +379.3 +256.3, 267.3
Data obtained from p. 32; Table 1, pp. 42

- 43; Table 5 , p. 50; and Appendix 1, p. 143, in the study report. USDA sediment texture confirmed determined by the reviewer using USDA

- NRCS technical support tools.

-- = not reported 1 Post acclimation (Day 0) 2 Day 62. 3 Day 100.



### B. Study Design

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

Table 5. Experimental Design

.

Experimental Design Goose River Choptank River

Duration of the test 100 days

Water:

Type and size of filter used 2

- mm mesh

Am ount of sediment and water per treatment:

Water (mL) 209 ca. 189

Sediment (g dry wt) ca. 43 ca . 65.0

Water:sediment ratio 1:3, v:v ( 2.2

- 2.5 cm layer of sediment covered with 6.6

- 7.5 cm of
water)

Application rates:

Nominal Not r eported

Actual 0.16

- 0.18 μ g a.i./mL

Number of replicates:

Control, if used Sterile controls were not used.

Treated Single samples ( one entire flask) of each label treatment/system w as collected at each sampling interval.

Test ap paratus:

Type/material/volume Amber glass bottles (250 mL) containing water and sediment were

attached to individual flow

- through volatile trapping systems and incubated in darkness in a temperature

- controlled room. The test systems were treated after at least 1 0 days of pre

- incubation. The test system is illustrated in Figure 2, p. 64

.

Details of traps for CO 2 and organic volatile, if

any Humidified air was drawn through a sample, then through one bottle of ethylene glycol and two bottles of 1N KOH. The volatile trapping system is illustrated in Figure 2, p. 64.

If no traps were used, is the system closed? Volatile traps were used.

Identity and final concentration (based on

water volume ) of co

- solvent Acetonitrile, 0.05% by volume

Test material application method:Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 7 of 21 Experimental Design Goose River Choptank River

Volume of the test solution used/treatment 100 μ L/sample

Application method ( i.e. , mixed/not mixed) T o the water surface using a glass volumetric syringe.

Any indication of the test material adsorbing to the walls of the test apparatus? None.

Microbial biomass in untreated samples ( μ g C/g sediment) Initial Final Initial Final

Water Not reported

Sediment 383 125 278 58

Experimental conditions:

Te mperature 20 ± 2 ° C, range not reported

Continuous darkness (yes/no) Yes

Other details (if any) Microbial activity was determined in samples that were treated with pesticide

- free acetonitrile

. Data obtained from pp. 22

- 25, 32; Table 2, p. 45; and Figure 2, p. 64, of the study report.



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

Table 6. Sampling during Study Period

.

Parameter Details

Sampling intervals (duration) 0, 1, 7, 14, 28, 62, 79, an d 100 days posttreatment.

Sampling method Per label/system type, single samples (one entire flask) was collected at each sampling interval.

Method of collection of CO 2 and organic volatile compounds Volatile tr aps were collected at each sampling interval.

Sampling Intervals/Times

Redox potential in water layer

Measured at each sampling interval Dissolved oxygen in water layer

pH in water layer

Redox potential in sediment

pH in sedi ment

Other details, if any Water and sediment extracts were analyzed by LSC on the day of sampling. Samples were analyzed using HPLC within 24 hours for water and 1 week for the sediment

extracts. Water and so il extracts were stored frozen when not in use.

Data obtained from pp. 25

- 26 , 38; Table 2, p. 47; and Tables 4

- 5, pp. 4 9

- 50, of the study report.



### 3. Analytical Procedures:

Separation of the Water and Sediment: The water layer was decanted into graduated cylinders (p.

2 6 ).

Extraction/Clean Up/Concentration Methods: Aliquots of the water were analyzed without modification using LSC (p. 26; Table 2, p. 47; Figure 3, p. 65). Additional aliquots were microfuged and/or filtered and ana lyzed using HPLC (p. 21).

The sediment w as soaked overnight with 0.1M ammonium acetate at ca. 5 ° C (p. 26 ; Figure 3 , p.
6 5 ) . The next day, the soils were extracted three times with methylene chloride:methanol: formic acid (75:25:1, v:v:v) by shaking for 1 hour/extraction at ambient temperatures . After each extraction, the samples were centrifuged and the supernatant decanted. The extracts were combinedChlorimuron ethyl (PC 128901 ) MRID 49526702

Page 8 of 21 

### aliquots were analyzed using LSC. The remaining extracts were concentrated by rotary evaporation, adjuste d to ca . pH 9, and refrigerated overnight

. The concentrate was centrifuged and the supernatant decanted . The supernatant was further concentrated, and aliquots were analyzed using LSC, HPLC, and TLC. The precipi t ate was dissolved in methylene chloride:meth anol (75:25,
v:v), an d aliquots analyzed using LSC. The precipitate from the day 62 Goose River clay loam sediment/pyrimidine label (7.1% of the applied) was analyzed using HPLC.

Determination of Unextracted R esidues: The extracted soils were homogenized and portions were analyzed for total remaining radioactivity using LSC following combustion ( p. 2 7; Figure 3 , p.
6 5 ).

Determination of Volatile Compounds: Aliquots of the trapping solutions were analyzed by LSC
( p. 27; Figure 3, p. 65 ). It was not confir med that residues in the KOH traps were CO 2



### .

Total Radioactivity Measurement: T otal [ 14 

### C]residues were determined by summing the concentrations of residues measured in the water layer, sediment extracts, extracted sediment and trapping solutions (Tables 6

- 7 , pp. 51

- 54 ).

Derivatization Method: A derivatization method was not described.

Identification and quantification of Parent and Transformation Compounds: Aliquots of the concentrated extracts were analyzed by reverse phase HPLC using a LUNA C18 colum n eluted with a gradient mobile phase of (a) 20mM ammonium acetate in HPLC grade water and (B) HPLC grade acetonitrile (p p 27

- 28 ). Samples were cochromatographed with a mixture of reference

standards.

Samples were also analyzed using one

- dimensional TLC o n silica gel plates develop in

chloroform:methanol: 1 M ammonium carbonate aqueous (150:30:3, v:v:v) or dichloromethane:acetone:methanol:88% formic acid (130:45:25:1, v:v:v:v; pp. 28

- 29). Samples were cochromatographed with a mixture of reference standards.

Detection Limits (LOD, LOQ) for the Parent and Transformation Products : For LSC, Limits
of Detection (L O D) were 0.03

- 0.04% of the applied for combusted soil, 0.004

- 0.005% for the KOH
solution, 0.06% for the aqueous solutions, and 0.21

- 0.22% for the organ ic extracts (Table 3, p. 48).
Limits of Quantification (LOQ) were 0.13

- 0.14%, 0.05

- 0.06%, 0.61

- 0.67%, and 2.31

- 2.51%

, respectively. For HPLC, the L O D was 0.004% of the applied and L O Q s were 0.006

- 0.007%

.

II. Results and Discussion

A. Data:

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

Tables 7a

- 7d . In the water column of the Goose River water:clay loam sediment systems following treatment, standard redox potentials, oxygen satur ation and pH were + 202.3 to + 465.3 mV, 4.16

- 8.70 ppm and 5.98

- 7.93 , respectively, with redox potentials and pH in the sediment of +78.3 to

+448.3 mV and 6.13

- 7.53 , respectively (Table 4, p. 49). In the water column of the Choptank River

water:sand sediment systems following treatment, standard redox potentials, oxygen saturation and
pH were + 243.3 to + 467.3 mV, 2.45

- 8.20 ppm and 5.73

- 8.29 , respectively, with redox potentialsChlorimuron ethyl (PC 128901 ) MRID 49526702

Page 9 of 21 

### and pH in the sediment of +39.3 to +474.3 mV and 5.65

- 7.57 , respectively (Table 5, p. 50). In both test systems, the water layer was generally oxic and the sediment varied from oxic to suboxic with no clear pattern during the experiment.

Sediment microbial biomass in the Goose River clay loam sediment was 383 μ g C/g sediment at

time 0 and 125 μ g C/g sediment at study termination (p. 32). Untreated sediment microbial biomass
in the Choptank River sand sediment was 278 μ g C/g sediment at time 0 and 58 μ g C/g sediment at study termination.

B. Mass Balance:

In the Goose River water:clay l oam sediment system, recoveries averaged 97.3 ± 1.8 % (sample
range 9 5.8

- 100.7%) of the applied for samples treated with the phenyl label and 97.1 ± 1.7 % ( 95.1

- 99.8 %) for samples treated with the pyrimidine label (Table 6, p. 51). Recoveries were within gui deline criteria (>90%

- <110%). In the water column, chlorimuron ethyl decreased from a

maximum of 98.5 % of the applied at time 0 to 11.6 % at 100 days posttreatment (Table 8, pp. 55

- 56). In the sediment, chlorimuron ethyl was a maximum of 29.4 % of the appl ied at 62 day s posttreatment and decreased to 4.8% at 100 days.

In the Choptank River water:sand sediment system, recoveries averaged 96.5 ± 3.7 % (sample range

91.0

- 103.9 %) of the applied for samples treated with the phenyl label and 95.3 ± 2.0 % ( 91.7

- 97. 9 %) for samples treated with the pyrimidine label (Table 7 , p. 5 3 ). Recoveries were within guideline
criteria (>90%

- <110%). In the water column, chlorimuron ethyl decreased from a maximum of

97.0 % of the applied at time 0 to 5.0% in the phenyl treatment and 26.2% in the pyrimidine

treatment at 100 days posttreatment (Table 9 , pp. 5 7

- 58 ). In the sediment, chlorimuron ethyl was a

maximum of 10.1 % of the applied at 79 day s posttreatment and decreased to 8.3% at 100 days.

C. Bound and Extractable Residues:

In the Goose River clay loam sediments, extractable radioactivity increased from 4.1% of the applied at time 0 to a maximum of 40.9% at 62 days posttreatment and was 36.5% at 100 days
(Table 6 , p. 51 ). Unextracted radioactivity increased from 0. 3 % of the a pplied at time 0 to a

maximum of 8.1 % at 10 0 days posttreatment.

In the Choptank River sand sediments, extractable radioactivity increased from 2.3 % of the applied

at time 0 to a maximum of 28.1% at 79 days posttreatment, and were 26.8 % at 10 0 days (Tabl e 7 , p.
53 ). Unextracted radioactivity increased from 0.0% of the applied at time 0 to a maximum of 1.1 %

at 62 and 10 0 days posttreatment.

D. Volatilization:

In the Goose River water:clay loam sediment systems, 14 

### CO 2 

### was 0.0% of the applied during the experiment (Table 6, p. 51). Organic volatiles totaled a maximum of 1.1% at 100 days posttreatment (Table 6, p. 51)

.

In the Choptank River water:sand sediment systems, 14 

### CO 2 

### was 0

- 5

- 0.7% of the applied at 79

- 100 days posttreatment (Table 7, p. 53) . Organ ic volatiles were 0.0% during the experiment.Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 10 of 21 

### Table 7a. Aerobic transformation of [phenyl

- U

14 

### C]chlorimuron ethyl, expressed as a percentage of the applied radioactivity, in Goose River water:clay loam sediment.

Sampling Interval (days) 0 1 7 14 28 62 7 9 100

Replicate Number A A A A A A A A

Chlorimuron ethyl (DPX

- F6025) 98.5 97.6 77.0 63.9 49.0 51.8 20.2 13.7

IN

- B4450 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0

IN

- L8330 0.0 0.7 14.0 27.7 41.0 33.3 63.5 66.6

IN

- 00581 0.0 0.0 2.5 0.0 0.8 6.1 5.9 6.5

IN

- B7497 0.0 0.0 0.0 0.0 0.0 2.9 0.0 2.1

Unknown 1 0.0 0.3 0.9 1.8 0.0 0.0 0.0 1.4

Others 0.0 0.0 0.0 0.0 0.0 0.0 1.0 0.0

Water 98.5 89.6 77.7 72.4 64.4 63.1 56.4 56.0

Extracted residues 0.0 9.3 17.3 21.9 28.3 32.0 34.9 36.5

Unextracted residues 0.0 0.2 1.5 2.4 4 .0 5.9 5.2 5.4

CO 2 

### n.a. 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Volatile organics n.a. 0.0 0.0 0.0 0.1 0.7 0.6 0.9

Mass balance 98.5 98.8 96.0 95.8 95.9 100.7 96.3 96.7

Data obtained from Table 6, p. 51, and Table 8, p. 55, of the study report. n.a. = not analyzed

.



### Table 7b. Aerobic transformation of [pyrimidine

- 2

- 14 

### C]chlorimuron ethyl, expressed as a percentage of the applied radioactivity, in Goose River water:clay loam sediment.

Sampling Interval (days) 0 1 7 14 28 62 79 100

Replicate Number A A A A A A A A

Chlorimuron ethyl (DPX

- F6025) 94.5 95.6 83.3 71.0 53.9 35.7 29.2 16.4

IN

- N6186 0.0 0.3 2.9 0.0 0.0 1.4 1.5 0.0

IN

- V9662 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

IN

- L8330 0.0 0.6 10.5 21.8 36.9 53.6 55.4 64.3

IN

- H1427 0.0 0.0 0.0 0.0 0.0 0.0 1.1 2.0

Others 0.0 0.0 0.0 0.0 0.0 3.2 1.0 6.2

Water 94.4 88.6 81.6 73.5 65.1 60.2 53.6 54.2

Extracted residues 4.1 8.1 15.5 19.6 26.5 40.9 35.5 35.4

Unextracted residues 0.3 0.3 1.1 2.7 4.1 5.3 6.7 8.1

CO 2 

### n.a. 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Volatile organics n.a. 0.0 0. 0 0.1 0.2 0.4 0.7 1.1

Mass balance 98.5 96.6 97.8 95.6 95.1 99.8 95.7 98.0

Data obtained from Table 6, p. 51, and Table 8, p. 56, of the study report. n.a. = not analyzed.Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 11 of 21 

### Table 7c. Aerobic transformation of [phenyl

- U

14 

### C]chlorimuron ethyl, expressed as a percentage of the applied radioactivity, in Choptank River water:sand sediment.

Sampling Interval (days) 0 1 7 14 28 62 79 100

Replicate Number A A A A A A A A

Chlorimuron ethyl (DPX

- F6025) 97.0 95.7 94.4 96.1 81.1 32.3 30.7 10.8

IN

- B4450 0.0 0.0 0.0 0.0 0.0 33.0 32.3 39.8

IN

- L8330 0.0 0.0 0.7 1.6 9.7 7.7 21.6 8.5

IN

- 00581 0.0 0.0 0.0 0.0 2.4 13.6 13.6 32.1

IN

- B7497 0.0 0.0 0.0 0.0 0.0 2.0 3.2 3.2

Unknown 1 0.0 0.0 0.6 0.4 0.0 0.0 0.0 0.0

Others 0.0 0.0 0.0 0.0 0.0 1.0 1.1 0.0

Water 97.0 95.7 85.0 87.6 80.3 68.0 75.0 68.1

Extracted residues 0.0 0.0 10.0 10.9 13.3 21.9 28.1 26.8

Unextracted residues 0.0 0.3 0.1 0.2 0.5 1.1 1.0 1.1

CO 2 

### n.a. 0.0 0.0 0.0 0.2 0.3 0.6 0.6

Volatile organics n.a. 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Mass balance 97.0 96.0 95.8 98.3 94.0 91.0 103.9 96.0

Data obtained from Table 7, p. 53, and Table 9, p. 57, of the study report. n.a. = not analyzed.



### Table 7d. Aerobic transformation of [pyrimidine

- 2

- 14 

### C]chlorimuron ethyl, expressed as a percentage of the applied radioactiv ity, in Choptank River water:sand sediment.
Sampling Interval (days) 0 1 7 14 28 62 79 100
Replicate Number A A A A A A A A Chlorimuron ethyl (DPX

- F6025) 94.3 95.0 96.7 91.4 81.8 65.1 54.6 34.5

IN

- N6186 0.0 0.0 0.5 0.0 0.0 5.7 1.3 33.0

IN

- V9662 0.0 0. 0 0.0 0.0 0.0 0.0 0.0 0.0

IN

- L8330 0.0 0.0 0.0 2.0 13.2 19.7 29.2 21.6

IN

- H1427 0.0 0.0 0.0 0.0 0.0 0.0 4.0 1.4

Others 0.0 0.0 0.0 0.0 0.0 0.0 6.7 2.6

Water 94.2 95.0 90.4 81.6 80.4 74.5 79.6 70.5

Extracted residues 2.3 0.0 7.0 12.1 15.1 16.5 17.9 23. 1

Unextracted residues 0.0 0.5 0.0 0.1 0.5 0.7 0.7 1.0

CO 2 

### n.a. 0.0 0.0 0.1 0.2 0.4 0.7 0.5
Volatile organics n.a. 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Mass balance 96.5 95.5 97.2 93.6 95.7 91.7 97.9 94.5

Data obtained from Table 7, p. 53, and Table 9, p. 58, of the study report. n.a. = not analyzed.



### E . Transformation of Parent Compound: Transformation kinetics of the parent compound in the total system are summarized in the following two Figu res , with transformation product information

summarized in Table 8

.

Single First Order, First Order Multi

- Compartment, Hockey Stick, and Double First

- Order in Parallel models were used by the study author to predict DT50 values (pp. 29

- 30, 36

- 37; Table 1 0, pp. 59

- 60). Total system SFO half

- lives were 40.8 and 41.5 days for the Goose River water:clayChlorimuron ethyl (PC 128901 ) MRID 49526702

Page 12 of 21 

### loam sediment systems treated with the phenyl and pyrimidine labels, respectively (p. 37). Total system SFO half

- lives were 44.1 and 85.2 days for the Choptan k River water:sand sediment systems treated with the phenyl and pyrimidine labels, respectively (pp. 37

- 38).

Kinetics models: Single First Order (SFO); Double First Order in Parallel (DF OP), and Indeterminate Order Rate Equation (IORE) in accordance with NAFTA kinetics guidance (USEPA, 2012). 

## Chlorimuron ethyl in aerobic water:clay loam sediment

Days %AR

0 1

7
14
28
62 79
100
0
1

7 14
28
62
79
100 98.5 97.6
77.0
63.9
49.0
51.8 20.2
13.7
94.5
95.6
83.3 71.0
53.9
35.7
29.2
16.4 0 20 40 60 80 100 0 20 40 60 80

TimeConcentration SFO

DFOP

IORE

-20 -10 0 10 20

-20 -10 0 10 20

-20 -10 0 10 20

0 20 40 60 80 100

D T 50 D T 90  2 C 0 Parameters

SFO 41.1 137 7.5 93.3 k  0.0168

DFOP 35.4 153 6.6 98.2 f  0.192   k 0  0.136   k 1  0.0136

IORE 33.7 215 7 96.8 N  1.69   k  0.00111 S C

S S F O S l o w   t 1 2

t R 

 I O R E 740

742

50.8

64.7



# Chlorimuron ethyl in aerobic water:sand sediment

Days %AR

0 1

7
14
28
62 79
100
0
1

7 14
28
62
79
100 97.0 95.7
94.4
96.1
81.1
32.3 30.7
10.8
94.3
95.0
96.7 91.4
81.8
65.1
54.6
34.5 0 20 40 60 80 100 0 20 40 60 80 100

TimeConcentration SFO

DFOP

IORE

-20 -10 0 10 20

-20 -10 0 10 20

-20 -10 0 10 20

0 20 40 60 80 100

D T 50 D T 90  2 C 0 Parameters

SFO 59.8 199 6.5 102 k  0.0116

DFOP 63.9 178 3.7 95.3 f  -0.236   k 0  0.137   k 1  0.0142

IORE 68 113 3.7 98.7 N  -0.2   k  1.71 S C

S S F O S l o w   t 1 2

t R 

 I O R E 1.53e+03

1.67e+03

49

33.9Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 13 of 21 

### Table 8. Transformation Products of Chlorimuron ethyl in the Water:Sediment Systems

.

Transformatio

n Products Maximum

%AR

Observed Associated

Inte rval

(days) Final %AR

Observed Final Interval (days)

Goose River, North Dakota

USA Water:clay loam sediment

(20 ° C, water pH 8.3, sediment pH 8.0) IN

- B4450 1.0 28 0.0 100

IN

- L8330 66.6 100 66.6 100

IN

- 00581 6.5 100 6.5 100

IN

- B7497 2.9 62 2.1 100

I N

- N6186 2.9 7 0.0 100

IN

- H1427 2.0 100 2.0 100

Choptank River, Maryland,

USA

Water: sand sediment

(20 ° C, water pH 6. 9

, sediment pH 6. 7 ) IN

- B4450 39.8 100 39.8 100

IN

- L8330 29.2 79 21.6 100

IN

- 00581 32.1 100 32.1 100

IN

- B7497 3.2 79, 100 3.2 100

IN

- N6186 33.0 100 33.0 100

IN

- H1427 4.0 79 1.4 100

Data obtained from Tables 8

- 9 , pp. 5 5

- 58 , in the study report.

IN

- B4450, IN

- 00581, and IN

- B7497 are products of the phenyl moiety only. IN

- N6186 and IN

- H1427 are products of

the pyrimidine moiety only.



### A transformation pathway was provided by the study authors (Figure 14 , p. 141 ).Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 14 of 21 

### III. Study Deficiencies and Reviewer's Comments

1. The pesticide use history at the source site was not reported, and it was not demonstrated that

the water and sediments were pesticide

- free prior to use.

2. In the Choptank River water:sand system treated with the phenyl label, the concentration of chlorimuron ethyl decreases ca. 50% between two sampling intervals, from 81.1% of the applied at 28 days posttreatment to 32.3% at 62 days (Table 9, p. 57). A similar large decrease was not seen with the pyrimidine label, or in the Goose River water:clay loam sediment system (Table 8, pp. 55

- 56; Table 9, p. 58).

IV. References

1. 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.

2. U.S. Environmental Protection Agency. 2012. NAFTA Guidance for Evaluating a nd Calculating Degradation Kinetics in Environmental Media.Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 15 of 21 DER ATTACHMENT 1. Chlorimuron ethyl and Its Environmental Transformation Products

. A

Code Name/ Synonym Chemical Name Chemical Structure Study
Type MRID Maximum %AR (day) Final %AR (study length )

PARENT

Chlorimuron ethyl (DPX

F6025) IUPAC: Ethyl 2

- (4

- chloro

- 6

- methoxypyrimidin

- 2

- ylcarbamoylsulfamoyl)benzoate

CAS: Ethyl 2

- [[[[(4

- chloro

- 6

- methoxy

- 2

- pyrimidinyl)amino]carbonyl]amin o]sulfonyl]benzoate

CAS No.: 90982

- 32

- 4

Formula: C 15 H 15 ClN 4 O 6 S

M W: 414.8 g/mol

SMILES: n1c(Cl)cc(OC)nc1NC(=O)NS(=O
)(=O)c2ccccc2C(=O)OCC Cl O C H 3

N

N N

H O

N

H S O

O C H 2 C H 3

O O 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 103.9% ( 0 d) 6.4% (124 d)

North Dakota

Clay loam 99.9% ( 0 d) 21.4% (124
d)

835.4300

A erobic aquatic

metabolism 49526702 River water: Clay loam 98.5% ( 0 d) 16 .4% (100 d)

River water:

Sand 97.0% ( 0 d) 34.5 % (100 d)

MAJOR (>10%) TRANSFORMATION PRODUCTS

IN

- L8330 IUPAC: Ethyl 2

- [(4

- chloro

- 6

- hydroxy

- pyrimidin

- 2

- yl)carbamoylsulfamoyl]b enzoate

Formula: C 14 H 13 ClN 4 O 6 S

MW: 400.8 g/mol

SMILES: [H]N(c1nc(cc(n1)Cl)O)C(=O)N([
H])S(=O)(=O)c2ccccc2C(=O)OC

C C H 2 C H 3

O

S

O O

H N O

H N N O H

Cl N O 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 39.4% ( 124 d) 39.4% (124
d)

North Dakota

C lay loam 6.8% ( 90 d) 4.6% (124 d)

835.4300

Aerobic aquatic

metabolism 49526702 River water: Clay loam 66.6% ( 100 d) 66.6 % (100 d)

River water:

Sand 29.2% ( 79 d) 21.6 % (100 d)Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 16 of 21 Code Name/ Synonym Chemical Name Chemical Structure Study
Type MRID Maximum %AR (day) Final %AR (study
length )

IN

- N6186 IUPAC: 4

- Chloro

- 6

- methoxy

pyrimidin

- 2

- amine

F ormula: C 5 H 6 ClN 3 O

MW: 159.6 g/mol

SMILES: [H]N([H])c1nc(cc(n1)Cl)OC

N H

H Cl O C H 3

N

N 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 20.1% ( 29 d) 18.9 % (124
d)

North Dakota

Clay loam 56.9% ( 124 d) 56.9% (124 d)

835.4300

Aer obic aquatic

metabolism 49526702 River water: Clay loam 2.9% ( 7 d) 0.0% (100 d)

River water:

Sand 33.0% ( 100 d) 33.0 % (100
d)

IN

- B4450 IUPAC: Ethyl 2

- sulfamoylbenzoate

Formula: C 9 H 11 NO 4 S

MW: 229.2 g/mol

SMILES:
[H]N([H])S(=O)(=O)c1ccccc1C(
=O)OCC C H 2 C H 3

O

S

O O

H N H O 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 2.6% ( 7 d) 1.0% (124 d)

North Dakota

Clay loam 41.3 % ( 124 d) 41.3 % (124 d)

835.4300

Aerobic aquatic

metabolism 49526702 River water: Clay loam 1.0 % ( 28 d) 0.0% (100 d)

River water:

Sand 39.8% ( 100 d) 39.8 % (100 d)

IN

- 00581 (Saccharin) IUPAC: 1,1

- Dioxo

- 1,2

- benzothiazol

- 3

- one

Formula: C 7 H 5 NO 3 S

MW: 183.2 g/mol

SMILES:
[H]N1C(=O)c2ccccc2S1(=O)=O O

N H

S O

O 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 5.3 % ( 7 d) 4.7 % (124 d)

North Dakota

Clay loam 46.3 % ( 29 d) 30.6 % (124 d)

835.4300

Aerobic aquatic

metabolism 49526702 River water: Clay loam 6.5 % ( 100 d) 6.5 % (100 d)

River wate r: Sand 32.1% ( 100 d) 32.1 % (100 d)

Met

- 1 NA Structure not provided 835.4100 49526701 IllinoisChlorimuron ethyl (PC 128901 ) MRID 49526702

Page 17 of 21 Code Name/ Synonym Chemical Name Chemical Structure Study
Type MRID Maximum %AR (day) Final %AR (study
length )

Aerobic soil

metabolism Clay loam 8.4 % ( 29 d) 0.0 % (124 d)

North Dakota

Clay loam 10.2 % ( 29 d) 0.0% (124 d)

Carbon dioxide IUPAC: Carbon dioxide

Formula: CO 2 MW: 44 g/mol

SMILES: C(=O)=O

C O O 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 23.3% ( 124 d) 23.3% (124 d)

North Dakota

Clay loam 2.5% ( 124 d) 2.5 % (124 d)

835.4300

Aerobic aquatic

metabolism 49526702 River water:

Sand 0.7 % ( 79 d) 0.6 % (100 d)

Unextractable residues

NA NA 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 15.2 % ( 90 d) 15.0 % (124 d)

MINOR (< 10%) TRANSFORMATION PRODUCTS

IN

- B7497 IUPA C: Ethyl 2

- (carbamoylsulfamoyl)benzoate

Formula: C 10 H 12 N 2 O 5 S

MW: 272.3 g/mol

SMILES:
[H]N([H])C(=O)N([H])S(=O)(=O
)c1ccccc1C(=O)OCC C H 2 C H 3

O O

S O

N H

H

O N

H O 835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 2.0% ( 61

- 90 d) 0.0% (124 d)

North Dakota

Clay loam 2. 4 % ( 7 d) 0.0 % (124 d)

835.4300

Aerobic aquatic

metabolism 49526702 River water: Clay loam 2.9 % ( 62 d) 2.1 % (100 d)

River water:

Sand 3.2 % ( 79

- 100 d) 3.2 % (100 d)Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 18 of 21 Code Name/ Synonym Chemical Name Chemical Structure Study
Type MRID Maximum %AR (day) Final %AR (study
length )

IN

- V9662 IUPAC: (4

- Chloro

- 6

- methoxy

pyrim idin

- 2

- yl)urea

Formula: C 6 H 7 ClN 4 O 2 MW: 202.6 g/mol

SMILES:
[H]N([H])C(=O)N([H])c1nc(cc(n 1)Cl)OC N

O N

H H N H

N Cl O C H 3

835.4100

Aerobic soil

metabolism 49526701 Illinois Clay loam 2. 7 % ( 29 d) 0.0% (124 d)

IN

- H1427 IUPAC: 2

- Amino

- 6

- methoxy

pyrimidi n

- 4

- ol

Formula: C 5 H 7 N 3 O 2 MW: 141.1 g/mol

SMILES:
[H]N([H])c1nc(cc(n1)OC)O N

N

H H

N O H O C H 3

835.4300

Aerobic aquatic

metabolism 49526702 River water: Clay loam 2.0 % ( 100 d) 2.0 % (100 d)

River water:

Sand 4.0 % ( 79 d) 1.4 % (100 d)

REFERENCE COMPOUNDS NOT IDENTIFIED

IN

- H9235 IUPAC: 2

- Amino

- 6

- methoxy

pyrimidin

- 4

- ol

Formula: C 5 H 7 N 3 O 2 MW: 141.1 g/mol

SMILES:
[H]N([H])c1nc(cc(n1)OC)O N H

H

O H O

C H 3 N

N 835.4100

Aerobic soil

metabolism 49526701 NA NA

IN

- D5119

- 001 IUPAC: 2

- Sulfamoylbenzoic

acid

Formula: C 7 H 7 NO 4 S

MW: 201.2 g/mol

SMILES:
[H]NS(=O)(=O)c1ccccc1C(=O)O O

O H

S O

O

N

H 835.4100

Aerobic soil

metabolism 49526701 NA NA

IN

- F8174

- 001

NA Structure not provided 835.4100

Aerobic soil

metabolism 49526701 NA NA

A AR means “appl ied radioactivity”. MW means “molecular weight”. NA means “not applicable”.Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 19 of 21 

### Attachment 2: Statistics Spreadsheets and GraphsChlorimuron ethyl (PC 128901 ) MRID 49526702

Page 20 of 21 

### Attachment 3: Calculation s

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

Single First

- Order (SFO) Model

(eq. 1)

where,

C t 

### = concentration at time t (%)

C 0 

### = 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 softwa re by adjusting C 0 

### and k to minimize the objective function (S SFO 

### ) shown in equation 9.

DT 50 

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

DT 90 

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

Indeterminate Order Rate Equation (IORE) Model

(eq. 4)

where,
N = order of decline rate (

- )

k IORE 

### = 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 DT 90 

### of
the IORE model. (Traditional DT 50 

### and DT 90 

### values for the IORE model can be calculated using equations 6 and 7.)

(eq. 5)

DT 50 

### = 1)

- k(N C

- /2) (C N)

- (1 0 N)

- (1 0 

### (eq. 6)

DT 90 

### = 1)

- k(N C

- /10) (C N)

- (1 0 N)

- (1 0 

### (eq. 7)Chlorimuron ethyl (PC 128901 ) MRID 49526702

Page 21 of 21 

### Double First

- Order in Parallel (DFOP) Model

(eq. 8)

where, g = the fraction of C 0 

### applied to compartment 1 (

- )

k 1 

### = rate constant for compartment 1 (d

- 1 

### )

k 2 

### = rate constant for compartment 2 (d

- 1 

### )

If C 0 

### x g is set equal to a and C 0 

### (1

- g) is set equal to c , then the equation can be solved with R

kinetics software for a
, c
, k 1 

### , and k 2 

### by minimizing the objective function (S DFOP 

### ) as described in equation 9.

DT 50 

### and DT 90 

### values can be calculated using equations 2 a nd 3, with k 1 

### or k 2 

### in place of k.

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

### , S IORE 

### , or S DFOP 

### ).

(eq. 9)

where,

S SFO 

### , S IORE 

### , or S DFOP 

### = objective function of kinetics model fit (% 2 

### )

n = nu mber of data points (

- )

C model,t 

### = modeled value at time corresponding to C d,t 

### (%)

C d,t 

### = experimental concentration at time t (%)

Critical Value to Determine Whether SFO is an Adequate Kinetics Model

If S SFO 

### is less than S C 

### , the SFO model is adequate to describe kinetics. If not, the faster of t IORE 

### or
the DFOP DT 50 

### for compartment 2 should be used.

(eq. 10)

where,

S
c 

### = 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