Test Material: Nicosulfuron 

MRID 49169703 

Title: Sarff, P. 2004. Rate of 14C-Nicosulfuron Degradation in Three Soils. 

EPA PC Code: 129008 

OCSPP Guideline: 835.4100 

For CDM Smith 

 

Primary Reviewer: Joan Harlin Signature: 

Date: 3/20/14 

 

Secondary Reviewer: Kathleen Ferguson Signature: 

Date: 3/20/14 

 

QC/QA Manager: Joan Gaidos Signature: 

Date: 3/20/14 
Nicosulfuron (PC 129008) MRID 49169703 

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Aerobic degradation of Nicosulfuron in three soils 

Report: MRID 49169703. Sarff, P. 2004. Rate of 14C-Nicosulfuron Degradation in Three 

Soils. Unpublished study performed by ABC Laboratories, Inc., Columbia, 

Missouri and DuPont Crop Protection, Newark, Delaware; sponsored and 

submitted by E.I. du Pont de Nemours and Company, Wilmington, Delaware. 

DuPont Study No.: 10929; ABC Study No.: 47547. Experimental work 

conducted between August 13, 2002 and November 19, 2003 (p. 6). Final report 

issued April 1, 2004. 

Document No.: MRID 49169703 

Guideline: OCSPP 835.4100 

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

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

and a certification of authenticity statement were provided (pp. 2-5). 

Classification: This study is Supplemental. The soil extraction procedures were not adequate 

to extract all identifiable [14C]residues in the soils; unextracted residues totaled a 

maximum of 30.0-40.2% of the applied. The pesticide use history at the soil 

source sites was not reported, and it was not confirmed that the soils were free of 

pesticide residues. 

PC Code: 129008 

Reviewer: Gabe Rothman Signature: 

Environmental Scientist Date: August 24, 2015 

EXECUTIVE SUMMARY 

The aerobic transformation of [pyridine-2-14C]- and [pyrimidine-2-14C]-labeled nicosulfuron was 

studied in three European souls: a sandy loam from Denmark (Flakkebjerg; pH 6.14), a clay loam 

from France (Champenoux, pH 5.35), and a loam from Germany (Gross-Umstadt, pH 7.48). The 

samples were incubated in darkness at 20C and ca. 50% of the 0 bar moisture holding capacity. 

The aerobic metabolism of nicosulfuron (both labels) was also studied in the Champenoux clay 

loam soil at 10°C under the same test conditions. The soil was treated at 0.08 mg a.i./kg, equivalent 

to a field rate of 0.06 kg a.i./ha. A continuous flow-through volatile trapping system was used. It 

was not confirmed that aerobic conditions were maintained in the soils throughout the study. The 

soils were viable at study initiation and termination. 

20°C experiments: The overall material balance averaged 100.0 ± 3.2% (range 95.8-106.0%) of the 

applied for the pyridine label and 98.6 ± 2.3% (range 95.2-102.7%) for the pyrimidine label in the 

Flakkebjerg sandy loam soil; 97.2 ± 4.4% (range 85.7-101.8%) for the pyridine label and 94.6 ± 

3.3% (range 87.5-98.5%) for the pyrimidine label in the Champenoux clay loam soil; and 96.0 ± 

2.8% (range 90.8-99.6%) of the applied for the pyridine label and 96.3 ± 3.1% (range 91.3-100.8%) 

for the pyrimidine label in the Gross-Umstadt loam soil. There were no patterns of decline in 

recoveries over time. Recoveries generally met guideline criteria. 

10°C experiments: The overall material balance averaged 99.6 ± 2.9% (range 95.3-106.9%) for the 

pyridine label and 99.8 ± 3.1% (range 96.0-107.0%) for the pyrimidine label in the Champenoux 
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clay loam soil. There were no patterns of decline in recoveries over time. Recoveries met guideline 

criteria. 

DT50 values, calculated half-lives, and information on transformation products are listed in Table 1. 

For the 20oC experiments, half-lives were 51.4 days in the Flakkebjerg sandy loam soil, 15.8 days in 

the Champenoux clay loam soil, and 18.4 days in the Gross-Umstadt loam soil. Major 

transformation products identified were IN-HYY21, IN-J0290, and IN-V9367. For the 10oC 

experiment, the half-life was 156 days for the Champenoux clay loam soil. Major transformation 

products identified were IN-J0290 and IN-V9367. 

20oC experiments: In the Flakkebjerg sandy loam soil (combined labels), total extractable 

radioactivity declined from 97.1% of the applied at time 0 to 88.7% at 120 days posttreatment. 

Unextracted radioactivity increased to a maximum of 32.5% of the applied at 120 days. 

Evolved 14CO2 totaled a maximum of 9.0% of the applied at study termination; other volatiles were 

not detected.

In the Champenoux clay loam soil (combined labels), total extractable radioactivity declined from 

95.5% of the applied at time 0 to 84.4% at 120 days posttreatment. Unextracted radioactivity 

increased to a maximum of 30.0% of the applied at 120 days posttreatment. Evolved 14CO2 totaled a 

maximum of 3.6% of the applied at study termination; other volatiles were not detected.

In the Gross-Umstadt loam soil (combined labels), total extractable radioactivity declined from 

98.8% of the applied at time 0 to 59.7% at 120 days posttreatment. Unextracted radioactivity 

increased to a maximum of 40.2% of the applied at 90 days, and was 39.0% at 120 days. Following 

humic/fulvic extraction of the Gross-Umstadt loam 120-day sample, fulvic acid was 25.0% of the 

applied, humic acid was 6.0%, and humin was 8.0%. 

10oC experiments: In the Champenoux clay loam soil (combined labels), total extractable 

radioactivity declined from 97.1% of the applied at time 0 to 86.7% at 120 days posttreatment. 

Unextracted radioactivity increased to a maximum of 19.0% of the applied at 90 days posttreatment 

and was 18.3% at 120 days. Evolved 14CO2 totaled a maximum of 0.6% of the applied at study 

termination; other volatiles were not detected.
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Table 1. Results Synopsis: Aerobic Soil Metabolism of Nicosulfuron 

Soil Location and Texture (Temperature, pH) 

Observed 

DT50 (days) 

Calculated 

Half-life

A

(days) 

Model 

Parameters and 

Statistics 

Transformation Products (maximum % AR, a

Major 

Denmark Flakkebjerg Sandy loam soil (20C, pH 6.14) 

ca. 41 51.4 DFOP 

C0 = 95.4 

f = 0.27 

K0 = 0.0605 

K1 = 0.00784 

Slow t1/2 = 88.4 

IN-J0290 (21.3% at 90 days) IN-HYY21 (13.8% at 90 days) IN-V9367 (52.2% at 120 days) Unextracted residues (32.5% at 120 

days) 

IN-74427 (1IN-69188 (2CO2 (9.0% a

France Champenoux Clay loam soil (20C, pH 5.35) 

ca. 14 15.8 IORE 

C0 = 93.8 

N = 1.6 

k = 0.0035 

tR IORE = 27.7 

IN-J0290 (48.8% at 62 days) IN-V9367 (72.4% at 120 days) Unextracted residues (30.0% at 120 

days) 

 IN-HYY21 IN-37740 (2IN-74427 (2IN-77799 (3IN-69188 (2CO2 (3.6% a

Germany Gross-Unstadt Loam soil (20C, pH 7.48) 

ca. 18 18.4 IORE 

C0 = 96.9 

N = 1.35 

k = 0.00865 

tR IORE = 24.9 

IN-HYY21 34.9% at 120 days) Unextracted residues (40.2% at 90 days) 

IN-GDC42 (IN-V9367 (6IN-37740 (5CO2 (5.5% a

France Champenoux Clay loam soil (10C, pH 5.35) 

>120 156 DFOP 

C0 = 94.8 

f = 0.351 

K0 = 0.0214 

K1 = 0.00184 

Slow t1/2 = 378 

IN-J0290 (16.7% at 90 days) IN-V9367 (35.3% at 120 days) Unextracted residues (19.0% at 90 days) 

CO2 (0.6% a

A Model was selected in accordance with the NAFTA kinetics guidance (USEPA, 2012). Double First Order in Parallel (DFOP), and In

Equation (IORE) 

B AR means “applied radioactivity”. 
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I. Materials And Methods 

A. Materials: 

1. Test Material [Pyridine-2-14C]- and [pyrimidine-2-14C]-labeled nicosulfuron 

(DPX-V9360; p. 20, Figure 1, p. 68) 

Pyridine-2-label 

Specific activity: 62.9 μCi/mg (pp. 19-20) 

Radiochemical purity: 98.0% (HPLC) 

Chemical purity: Not reported 

Lot No.: 2385-050 

Pyrimidine-2-label 

Specific activity: 62.2 μCi/mg (pp. 19-20) 

Radiochemical purity: 98.6% (HPLC) 

Chemical purity: Not reported 

Lot No.: 2406-007 

Solubility in water: Not reported 

2. Reference Compounds: The following standards were used in the analysis (Table 2).

Table 2. Reference Compounds 

Applicant’s 

Code Name Chemical Name Purity (%) Lot No. 

Nicosulfuron 

(DPXV9360) 

2-{{{{(4,6-Dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-

N,N-dimethyl-3-pyridinecarboxamide 97.9 116 

IN-V9367 2-(Aminosulfonyl)-N,N-dimethyl-3-pyridinecarboxamide 99.7 3 

IN-37740 2-[[(3,4-Dihydro-6-methoxy-4-oxopyrimidin-2-

yl]aminocarbonyl)aminosulfonyl]-N,N-dimethyl-3-pyridinecarboxamide NR 4 

IN-J0290 4,6-Dimethoxy-2-pyrimidinamine 99.9 3 

IN-H1043 2-Amino-6-hydroxy-4(1H)-pyrimidinone 99.2 7 

IN-74427 2-[(4,6-Dimethoxy-2-pyrimidinyl)-amino]-N,N-dimethyl-3-

pyridinecarboxamide 99.4 2 

IN-W9807 2-[[(4,6-Dimethoxypyrimidin-2-yl)aminocarbonyl]aminosulfonyl]-Nmethyl-3-pyridinecarboxamide 97.2 3 

IN-64554 Isothiaxolo[5,4-B]pyridine-3(2H)-one, 1,1-dioxide 99.5 2 

IN-GDC42 2-[[[[(Aminocarbonyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-

pyridine-carboxamide -- -- 

IN-77799 2-[(Aminocarbonyl)[4-methoxy-6-(methyldioxy)-2-pyrimidinyl]amino]-

N,N-dimethyl-3-pyridinecarboxamide -- -- 

IN-69188 -- -- -- 

IN-H9235 -- -- -- 

IN-HYY21 2-[[[[(Amonoiminomethyl)amino]-carbonyl]amino]sulfonyl]-N,Ndimethyl-3-pyridinecarboxamide -- -- 

Data obtained from pp. 20-21 and Figure 1, pp. 68-72 of the study report. 

-- = not reported. 
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3. Soil: Soil collection and characterization are summarized in Table 3 and Table 4, respectively. 

Table 3. Description of Soil Collection and Storage 

Description Flakkebjerg Champenoux Gross-Umstadt 

Geographic location Flakkebjerg, Denmark Champenoux, France Gross-Umstadt, Germany 

Soil series Not reported 

Pesticide use history at 

the collection site Not reported 

Collection date Not reported 

Collection procedures Not reported 

Sampling depth Not reported 

Storage temperature ca. 4°C 

Storage length Not reported. 

Soil preparation Sieved (ca. 2 mm) 

Data obtained from pp. 22, 37; and Table 1, p. of the study report. 

Table 4. Properties of the Soil 

Property Flakkebjerg Champenoux Gross-Umstadt 

Soil Texture (USDA) Sandy loam Clay loam1 Loam 

% Sand 53.2 21.2 37.2 

% Silt 32.8 50.8 46.8 

% Clay 14.0 28.0 16.0 

pH (in water) 6.14 5.35 7.48 

Organic carbon (%)1 1.0 1.6 1.0 

Organic matter (%) (Walkley-Black) 2.1 2.1 1.8 

Cation Exchange Capacity (meq/100 

g) (method not reported) 9.90 17.73 10.66 

CaCO3 equivalence (%) 

Soil Moisture Content (%) 

0 bar 34.1 51.3 41.4 

0.1 bar 21.1 34.8 28.2 

0.33 bar 20.2 28.4 24.6 

Bulk density (g/cm3) 1.14 1.12 1.14 

Microbial Biomass in untreated soil 

(mg C/100 g soil) 

At initiation 92.6 132.8 128.6 

At termination 98.7 153.9 167.7 

Soil taxonomic classification Not reported Not reported Not reported 

Data obtained from p. 22, Table 1, p 49, and Table 2, p. 51, of the study report. The soil textures for the Flakkebjerg and 

Gross-Umstadt soils were confirmed using USDA-NRCS technical support tools. The soil texture for the Champenoux 

soil was determined by the reviewer to be a clay loam (see Reviewer’s Comment). 

1 Organic carbon = organic matter (%)/1.724. 
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B. STUDY DESIGN

1. Experimental Conditions: (Summarized in Table 5). 

Table 5. Experimental Design 

Property Details 

Duration of the test (days) 120 

Soil condition (Air dried/fresh) Fresh 

Soil (g/replicate) 50 g (dry wt) 

Application rates 

Nominal 0.08 μg a.i./g, equivalent to 60 g a.i./ha1 

Actual Pyridine = 0.0782 μg a.i./g (reviewer-calculated) 

Pyrimidine = 0.0786 μg a.i./g (reviewer-calculated) 

Control conditions (if used) Sterile controls were not used. 

Number of Replicates

Controls (if used) Sterile controls were not used. 

Treatment Single samples of each soil and label were collected at each sampling interval. 

Test apparatus 

Type/material/volume 

The test system consisted of 250-mL glass Erlenmeyer flasks containing moist 

treated soil (50 g dry wt) that were connected to a continuous flow through 

volatile trapping system. The bottles were kept in the dark in a temperaturecontrolled chamber. The test system is illustrated in Figure 2, p. 73. 

Details of traps for CO2

and other volatiles (if any)

Humidified, CO2-free air was pulled through the samples, then through one bottle 

of ethylene glycol and two bottles of 1N KOH traps. 

If no traps were used, is the 

system closed/open? Volatile traps were used. 

Identity and concentration of 

co-solvent 

Not applicable. Application solutions brought to volume with 10 mM ammonium 

acetate solution. 

Test Material: 

Volume of the test 

solution used/treatment 

Pyridine-2-14C label: 247 μL/vessel 

Pyrimidine-2-14C label: 241 μL/vessel 

Application method Applied with automatic pipette to sample surface, water added to bring to ca. 

50% of 0 bar moisture, and then soil mixed with a spatula. 

Is the co-solvent 

evaporated? Not applicable 

Any indication of the test 

material adsorbing to the walls 

of the test apparatus? 

No 

Experimental conditions: 

Temperature (C) 20 ± 2C, range 22.9-27.6C 

10 ± 2C, range 12.7-13.6C: Gross-Unstadt soil only 

Continuous darkness Yes 

Moisture content (MHC) ca. 50% of 0 bar moisture 

Moisture maintenance 

method Moisture levels adjusted as needed at least monthly with reagent water. 

Other details (if any) None 

Data obtained from pp. 23-26, 37; Table 2, pp. 50-51; and Figure 2, p. 73 of the study report. 

1 Field equivalence calculated by the study author assuming an incorporation depth of 5 cm and a soil bulk density of 

1.5 g/cm3

 (p. 19). 

2. Sampling During Study Period: (Details summarized in Table 6). 
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Table 6. Sampling During Study Period 

Criteria Flakkebjerg Champenoux Gross-Umstadt 

Sampling intervals (days) 

Both labels 0, 3, 7, 14, 21, 30, 45, 62, 76 (Gross-Umstadt only), 90, and 120 

Sampling method The entire flask was collected at each sampling interval. 

Method of collection of CO2 and 

organic volatile compounds 

Triplicate aliquots of the trapping solutions were collected at each sampling 

interval. The volatile trapping solutions were replaced with fresh material at 

each sampling event. 

Sampling intervals/times for: 

Sterility check (if used) Sterile controls were not used. 

Moisture content Moisture levels were adjusted as needed at least monthly with reagent water. 

Redox potential, other The redox potential was not measured. 

Sample storage before analysis

Soils were extracted immediately or stored frozen for ≤9 days. Extracts were 

stored frozen until analysis. Samples were generally analyzed within ca. 1 

month. 

Other observation (if any) None 

Data obtained from pp. 26-27 of the study report. 

3. Analytical Procedures

Extraction Methods: The soil was extracted three times by shaking for 30 minutes with 

acetone:0.01M ammonium carbonate (4:1, v:v; p. 27; Figure 2,p. 74). The extracts were combined, 

concentrated, and filtered. Aliquots were analyzed by LSC. Additional aliquots were concentrated 

to near dryness under nitrogen, reconstituted in water:methanol (95:5, v:v), filtered, and analyzed by 

LSC and HPLC. 

Determination of Unextracted Residues: The extracted soils were air-dried and homogenized via 

mechanical shaking (wrist action or horizontal platform shaker; p. 27). Due to inadequate 

homogenization, the samples after day 60 and select samples that showed poor replication in the 

original combustions were homogenized using a mortar and pestle (p. 28). Triplicate aliquots of the 

soil samples were analyzed by combustion followed by LSC. 

Determination of Volatile Compounds: Aliquots of the ethylene glycol and KOH trapping 

solutions were analyzed by LSC (p. 27). The presence of CO2 in the KOH solutions was confirmed 

by precipitation with barium chloride (p. 28). 

Total radioactivity measurement: Total [14C]residues were determined by summing the 

concentrations of residues in the soil extracts, extracted soil, and volatile traps (p. 38). 

Derivatization method A derivatization method was not employed. 

Identification and quantification of Parent and Transformation Compounds: The concentrated 

soil extracts were analyzed using reverse phase HPLC using Supelco Discovery C18 columns eluted 

with a mobile gradient phase of (A) methanol and (B) 0.1% formic acid (p. 30). The metabolites INV9367 and IN-GDC42 were separated using reverse phase HPLC using a Phenomenex Aqua 

column with a mobile phase of (A) methanol with 0.2% formic acid and (B) 0.2% formic acid (p. 

31). 

Extract solutions were cochromatographed with unlabeled reference standards (p. 30). 
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Transformation products were separated and positively identified in the soil extracts using 

LC/MS/MS (p. 27). 

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

analysis was twice background (pp. 30-31). For combustion LSC, the LOD was ca. 3.6 ppb (4.5% 

of the applied radioactivity (p. 35). For LSC of the soil extracts, the LOD was ca. 8.6 ppb (11% 

AR). For LSC of the KOH and ethylene glycol trapping solutions, the LOD was ca. 0.8 ppb (1% 

AR) and ca. 0.4 ppb (0.5% AR), respectively. For HPLC of the soil extracts, the LOD was ca. 0.3 

ppb (0.38% AR). 

II. Results and Discussion 

A. Data 

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

7. No determinations were made to verify that aerobic conditions were maintained in the soils. Soils 

were viable at study initiation and termination (Table 2, p. 51). 

B. Mass Balance 

20°C experiments: The overall material balance averaged 100.0 ± 3.2% (range 95.8-106.0%) of the 

applied for the pyridine label and 98.6 ± 2.3% (range 95.2-102.7%) for the pyrimidine label in the 

Flakkebjerg sandy loam soil; 97.2 ± 4.4% (range 85.7-101.8%) for the pyridine label and 94.6 ± 

3.3% (range 87.5-98.5%) for the pyrimidine label in the Champenoux clay loam soil; and 96.0 ± 

2.8% (range 90.8-99.6%) of the applied for the pyridine label and 96.3 ± 3.1% (range 91.3-100.8%) 

for the pyrimidine label in the Gross-Umstadt loam soil (Tables 3-4, pp. 52-55; Table 6, pp. 58-59). 

There were no patterns of decline in recoveries over time. Recoveries generally met guideline 

criteria. 

10°C experiments: The overall material balance averaged 99.6 ± 2.9% (range 96.0-107.0%) for the 

pyridine label and 99.8 ± 3.1% (range 95.9-106.9%) for the pyrimidine label in the Champenoux 

clay loam soil (Table 5, pp. 56-57). There were no patterns of decline in recoveries over time. 

Recoveries met guideline criteria. 

C. Unextracted and Extractable Residues 

20°C experiments: In the Flakkebjerg sandy loam soil (combined labels), total extractable 

radioactivity declined from 97.1% of the applied at time 0 to 88.7% at 120 days posttreatment 

(Table 3, pp. 52-53). Unextracted radioactivity increased to a maximum of 32.5% of the applied at 

120 days. 

In the Champenoux clay loam soil (combined labels), total extractable radioactivity declined from 

95.5% of the applied at time 0 to 84.4% at 120 days posttreatment (Table 4, pp. 54-55). Unextracted 

radioactivity increased to a maximum of 30.0% of the applied at 120 days posttreatment. 

In the Gross-Umstadt loam soil (combined labels), total extractable radioactivity declined from 

98.8% of the applied at time 0 to 59.7% at 120 days posttreatment (Table 6, pp. 66-67). Unextracted 
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radioactivity increased to a maximum of 40.2% of the applied at 90 days, and was 39.0% at 120 

days. Following humic/fulvic extraction of the Gross-Umstadt loam 120-day sample, fulvic acid 

was 25.0% of the applied, humic acid was 6.0%, and humin was 8.0% (p. 42). 

10oC experiments: In the Champenoux clay loam soil (combined labels), total extractable 

radioactivity declined from 97.1% of the applied at time 0 to 86.7% at 120 days posttreatment 

(Table 5, pp. 56-57). Unextracted radioactivity increased to a maximum of 19.0% of the applied at 

90 days posttreatment and was 18.3% at 120 days. 

D. Volatilization 

At 120 days posttreatment evolved 14CO2 totaled a maximum of 9.0% in the Flakkebjerg sandy 

loam soil, 3.6% in the Champenoux clay loam soil, and 5.5% in the Gross-Unstadt loam soil 

(Tables 3-4, pp. 52-55; Table 6, pp. 58-59). Volatile organics were not detected. 

10°C - At 120 days posttreatment evolved 14CO2 totaled a maximum of 0.6% in the Champenoux 

clay loam soil (Table 5, pp. 55-56). Volatile organics were not detected. 
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Table 7a. Transformation of [pyridine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity, in 

loam soil at 20°C. Sampling Interval (days) 0 3 7 14 21 30 45 62 

Nicosulfuron (DPX-V9360) 91.0 97.6 83.2 67.1 68.7 56.1 41.7 40.6 IN-HYY21 nd nd nd nd 1.3 2.5 5.3 1.6 IN-V9367 nd 4.6 10.6 19.0 17.8 30.4 39.9 40.9 IN-74427 nd nd nd nd nd nd nd nd IN-69188 nd nd nd 0.7 1.0 0.7 0.9 1.4 Unassigned radioactivity1 0.5 nd 0.9 1.7 1.7 1.1 1.2 2.7 Extracted residues 91.5 102.4 95.1 88.9 90.4 90.7 89.0 87.3 Unextracted residues 6.1 3.5 4.8 10.2 7.4 8.1 10.2 8.4 14CO2 na nd nd nd nd 0.1 0.1 0.2 Organic volatiles na nd nd nd nd nd nd nd Mass balance 97.7 106.0 99.9 99.1 97.8 98.9 99.4 95.8 

Data obtained from Table 3, p. 52 and Table 7, p. 60 of the study report. na = not analyzed; nd = not detected. 1 Unidentified radioactivity in extracts. 

Table 7b. Transformation of [pyrimidine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity

loam soil at 20°C. Sampling Interval (days) 0 3 7 14 21 30 45 62 

Nicosulfuron (DPX-V9360) 96.9 83.9 88.0 70.8 64.4 66.3 58.4 48.3 IN-HYY21 nd 1.4 nd 0.9 0.7 1.1 2.0 2.0 IN-J0290 nd 2.4 4.9 11.4 13.3 13.4 11.4 19.5 IN-74427 nd nd nd nd nd nd nd 0.4 IN-69188 nd nd nd 0.6 0.9 1.2 1.5 1.7 Unassigned radioactivity1 nd 4.5 0.5 0.7 1.0 0.5 0.4 1.1 Extracted residues 97.1 93.4 93.8 84.4 80.4 82.4 73.7 73.1 Unextracted residues 1.2 3.8 4.4 16.3 13.9 12.9 20.7 20.5 14CO2 na 0.05 0.2 0.7 0.8 1.8 3.0 4.0 Organic volatiles na nd nd nd nd nd nd nd Mass balance 98.3 97.2 98.4 101.4 95.2 97.1 97.4 97.6 

Data obtained from Table 3, p. 53 and Table 7, p. 61 of the study report. na = not analyzed; nd = not detected. 1 Unidentified radioactivity in extracts. 
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Table 7c. Transformation of [pyridine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity, in 

loam soil at 20°C. Sampling Interval (days) 0 3 7 14 21 30 45 62 

Nicosulfuron (DPX-V9360) 94.9 73.6 66.5 46.0 35.8 32.5 21.1 15.4 IN-HYY21 nd nd 0.4 nd nd 0.8 1.1 1.6 IN-V9367 0.6 8.4 21.5 34.9 40.9 49.7 56.1 66.4 IN-37740 nd 0.5 1.3 2.9 1.8 1.8 1.2 1.1 IN-74427 nd nd nd 0.7 nd nd nd nd IN-77799 nd nd 1.0 nd 2.4 3.1 1.7 2.5 IN-69188 nd nd 0.5 nd nd nd 1.7 0.4 Unassigned radioactivity1 nd nd nd 2.5 0.6 nd 2.4 1.5 Extracted residues 95.5 82.7 91.1 87.8 82.0 88.0 85.2 88.9 Unextracted residues 2.9 2.9 6.4 10.8 16.2 11.9 11.3 10.3 14CO2 na nd nd nd nd 0.04 0.1 0.2 Organic volatiles na nd nd nd nd nd nd nd Mass balance 98.4 85.7 97.5 98.6 98.2 100.0 96.6 99.4 

Data obtained from Table 4, p. 54 and Table 8, p. 62 of the study report. na = not analyzed; nd = not detected. 1 Unidentified radioactivity in extracts. 
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Table 7d. Transformation of [pyrimidine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity

loam soil at 20°C. Sampling Interval (days) 0 3 7 14 21 30 45 62 

Nicosulfuron (DPX-V9360) 94.3 81.2 74.9 47.7 41.7 31.0 22.0 15.5 IN-HYY21 nd 2.7 nd nd 0.4 nd 0.6 1.2 IN-J0290 0.4 6.8 9.7 17.3 25.3 36.0 35.9 48.8 IN-37740 nd 0.6 0.8 2.1 2.2 1.9 1.5 1.4 IN-74427 nd nd nd nd 0.8 nd 1.0 1.7 IN-77799 nd nd 1.0 nd 0.9 0.9 1.0 0.4 IN-69188 nd nd nd 1.9 1.9 1.9 2.1 2.6 Unassigned radioactivity1 nd nd 0.5 nd nd 1.3 0.6 nd Extracted residues 94.9 91.8 87.1 69.4 73.4 73.1 64.9 71.6 Unextracted residues 3.4 6.7 9.8 25.1 18.7 19.0 21.4 20.2 14CO2 na nd 0.05 0.2 0.4 0.7 1.2 1.5 Organic volatiles na nd nd nd nd nd nd nd Mass balance 98.3 98.5 96.9 94.7 92.5 92.8 87.5 93.3 

Data obtained from Table 4, p. 55 and Table 8, p. 63 of the study report. na = not analyzed; nd = not detected. 1 Unidentified radioactivity in extracts. 
Nicosulfuron (PC 129008) MRID 49169703 

Page 14 of 30 

Table 7e. Transformation of [pyridine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity, in 

at 20°C. Sampling Interval (days) 0 3 7 14 21 30 45 62 7

Nicosulfuron (DPX-V9360) 96.5 84.1 72.9 56.8 44.7 33.5 22.0 14.7 9IN-HYY21 nd 1.9 4.2 11.3 18.4 21.3 27.5 29.8 3IN-GDC42 nd nd nd nd 2.8 2.3 4.3 4.8 nIN-V9367 nd 1.1 2.6 4.7 2.8 4.6 4.3 4.8 nIN-37740 nd 3.6 4.1 4.0 2.7 2.1 0.9 0.7 nUnassigned radioactivity1 nd 1.1 0.4 2.6 2.8 3.2 3.4 4.8 4Extracted residues 96.7 91.8 84.1 79.5 74.3 66.9 62.4 59.5 5Unextracted residues nd 5.2 15.2 18.0 25.1 23.6 33.0 34.7 314CO2 na 0.04 0.1 0.1 0.2 0.3 0.6 0.7 0Organic volatiles na nd nd nd nd nd nd nd nMass balance 96.7 97.0 99.3 97.6 99.6 90.8 96.0 94.9 92

Data obtained from Table 6, p. 58 and Table 10, p. 66 of the study report. na = not analyzed; nd = not detected; nr = not reported. 1 Unidentified radioactivity in extracts. 

Table 7f. Transformation of [pyrimidine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity

soil at 20°C. 

Sampling Interval (days) 0 3 7 14 21 30 45 62 7

Nicosulfuron (DPX-V9360) 98.8 85.2 73.1 54.4 44.1 33.6 27.2 14.6 1IN-HYY21 nd 2.8 4.8 10.6 12.5 22.1 24.8 31.5 2IN-GDC42 nd nd 0.6 2.6 2.9 3.7 4.1 5.2 6IN-37740 nd 3.1 4.2 5.5 2.9 2.2 1.4 0.6 0Unassigned radioactivity1 nd 1.5 0.9 1.9 9.7 3.2 3.5 3.6 7Extracted residues 98.8 92.8 83.5 75.0 72.0 64.9 61.0 55.6 5Unextracted residues nd 7.6 16.5 18.8 22.6 25.3 32.9 35.4 314CO2 na 0.1 0.7 1.0 1.5 2.0 2.7 3.4 3Organic volatiles na nd nd nd nd nd nd nd nMass balance 98.8 100.6 100.8 94.9 96.1 92.1 96.6 94.4 9

Data obtained from Table 6, p. 59 and Table 10, p. 67 of the study report. na = not analyzed; nd = not detected. 1 Unidentified radioactivity in extracts. 
Nicosulfuron (PC 129008) MRID 49169703 

Page 15 of 30 

Table 7g. Transformation of [pyridine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity, in 

soil at 10°C. 

Sampling Interval (days) 0 3 7 14 21 30 45 62 

Nicosulfuron (DPX-V9360) 96.4 91.1 87.7 78.3 81.4 72.5 67.5 62.7 IN-V9367 0.8 2.2 3.5 8.7 9.3 12.1 17.2 22.5 Unassigned radioactivity1 nd 0.4 0.6 2.0 1.5 1.7 3.3 3.8 Extracted residues 97.1 93.6 91.9 89.0 92.2 86.3 88.0 89.0 Unextracted residues 2.7 5.4 7.5 17.9 8.0 9.0 9.9 9.8 14CO2 na nd nd nd nd nd nd nd Organic volatiles na nd nd nd nd nd nd nd Mass balance 99.8 99.1 99.4 106.9 100.2 95.3 98.0 98.9 

Data obtained from Table 5, p. 56 and Table 9, p. 64 of the study report. na = not analyzed; nd = not detected. 1 Unidentified radioactivity in extracts. 

Table 7h. Transformation of [pyrimidine-2-14C]nicosulfuron, expressed as a percentage of the applied radioactivity

loam soil at 10°C. Sampling Interval (days) 0 3 7 14 21 30 45 62 

Nicosulfuron (DPX-V9360) 94.5 92.4 89.0 92.8 81.9 76.3 69.8 67.8 IN-J0290 0.4 1.3 1.8 4.3 5.9 7.4 10.7 11.7 Unassigned radioactivity1 0.7 0.5 1.9 1.5 2.1 2.1 3.5 5.8 Extracted residues 95.6 94.3 92.7 98.7 89.9 85.9 84.1 85.3 Unextracted residues 3.2 5.6 5.9 8.3 9.5 13.2 11.8 11.0 14CO2 na nd nd nd nd nd 0.09 0.2 Organic volatiles na nd nd nd nd nd nd nd Mass balance 98.8 99.9 98.6 107.0 99.4 99.1 96.0 96.5 

Data obtained from Table 5, p. 57 and Table 9, p. 65 of the study report. na = not analyzed; nd = not detected. 1 Unidentified radioactivity in extracts. 
Nicosulfuron (PC 129008) MRID 49169703 

Page 16 of 30 

E. Transformation of the Test Compound 

20oC experiments: Using Single First Order and ModelManager v. 1.1, the study author calculated 

combined label half-lives of 50 days in the Flakkebjerg sandy loam soil; 16 days in the 

Champenoux clay loam soil, and 18 days in the Gross-Umstadt loam soil (pp. 33, 43). The halflives calculated by the study author were similar to the combined label half-lives calculated by the 

reviewer. 

10oC experiments: Using Single First Order and ModelManager® version 1.1, the study author 

calculated a combined label half-life of 150 days in the Champenoux clay loam soil (pp. 33. 43). 

The half-life calculated by the study author was identical to the combined label half-life calculated 

by the reviewer using the IORE model (the DFOP model was the most appropriate model). 

Aerobic metabolism of Nicosulfuron in sandy loam at 20°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 90

 90

 120

 120

91.0

96.9

97.6

83.9

83.2

88.0

67.1

70.8

68.7

64.4

56.1

66.3

41.7

58.4

40.6

48.3

29.0

35.7

22.2

34.5

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 20 40 60 80 100

DT50 DT90 

2 C0 Parameters

SFO 59.1 196 5.2 90 k  0.0117

DFOP 51.4 254 3 95.4 f  0.27k0  0.0605k1  0.00784

IORE 50.2 479 2.9 94.9 N  2.05k  0.00017

SC

SSFO

Slowt1 2

tRIORE

 628

 784

88.4

 144

Aerobic metabolism of Nicosulfuron in clay loam soil at 20°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 90

 90

 120

 120

94.9

94.3

73.6

81.2

66.5

74.9

46.0

47.7

35.8

41.7

32.5

31.0

21.1

22.0

15.4

15.5

8.20

10.6

4.60

5.80

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE -5

0

5

-5

0

5

-5

0

5

0 20 40 60 80 100120

DT50 DT90 

2 C0 Parameters

SFO 19.8 65.8 8.7 88.7 k  0 .035

DFOP 15.5 89.5 4.2 94 f  0.5k0  0.0 909k1  0.0 18

IORE 15.8 91.9 4.2 93.8 N  1.6k  0.0035

SC

SSFO

Slowt1 2

tRIORE

 199

 485

38.5

27.7
Nicosulfuron (PC 129008) MRID 49169703 

Page 17 of 30 

Kinetics models: Single First-Order (SFO); Double First-Order in Parallel (DFOP), and Indeterminate Order Rate 

Equation (IORE). Model was elected in accordance with the NAFTA kinetics guidance (USEPA, 2012).

Transformation products identified in the soil are presented in Table 8. No major transformation 

products were isolated. 

Aerobic metabolism of Nicosulfuron in loam soil at 20°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 76

 76

 90

 90

 120

 120

96.5

98.8

84.1

85.2

72.9

73.1

56.8

54.4

44.7

44.1

33.5

33.6

22.0

27.2

14.7

14.6

9.30

10.2

7.70

8.30

4.80

5.20

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

0 20 40 60 80 100

DT50 DT90 

2 C0 Parameters

SFO 21.2 70.4 5.3 93.6 k  0.0327

DFOP 18.1 81 1.7 97.5 f  0.342k0  0.0894k1  0.0233

IORE 18.4 82.7 1.9 96.9 N  1.35k  0.00865

SC

SSFO

Slowt1 2

tRIORE

43.9

 180

29.7

24.9

Aerobic metabolism of Nicosulfuron in clay loam soil at 10°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 90

 90

 120

 120

96.4

94.5

91.1

92.4

87.7

89.0

78.3

92.8

81.4

81.9

72.5

76.3

67.5

69.8

62.7

67.8

52.7

59.7

47.1

57.2

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 20 40 60 80 100

DT50 DT90 

2 C0 Parameters

SFO 128 425 2.5 92 k  0.00542

DFOP 156 1019 1.1 94.8 f  0.351k0  0.0214k1  0.00184

IORE 150 4051 1.1 95 N  2.85k  2.02e-06

SC

SSFO

Slowt1 2

tRIORE

 259

 322

 378

1.22e+03
Nicosulfuron (PC 129008) MRID 49169703 

Page 18 of 30 

Table 8. Transformation Products of Nicosulfuron in Soil 

Transformation 

Products 

Maximum 

%AR Observed

Associated 

Interval 

(days) 

Final %AR 

Observed 

Final Interval 

(days) 

Denmark 

Flakkebjerg 

sandy loam soil 

(20C, pH 6.14) 

IN-HYY21 13.8 90 10.0 120 

IN-J0290 21.3 90 14.7 120 

IN-V9367 52.2 120 52.2 120 

IN-74427 1.4 90, 120 1.4 120 

IN-69188 2.2 120 2.2 120 

France 

Champenoux 

clay loam soil 

(20C, pH 5.35) 

IN-HYY21 4.6 90 1.8 120 

IN-J0290 48.8 62 48.5 120 

IN-V9367 72.4 120 72.4 120 

IN-37740 2.9 14 0.7 120 

IN-74427 2.5 120 2.5 120 

IN-77799 3.1 30 1.8 120 

IN-69188 2.6 62 2.4 120 

Germany 

Gross-Unstadt 

loam soil 

(20C, pH 7.48) 

IN-HYY21 34.9 120 34.9 120 

IN-GDC42 7.0 120 7.0 120 

IN-V9367 6.2 120 6.2 120 

IN-37740 5.5 14 0.6 120 

France 

Champenoux 

clay loam soil 

(10C, pH 5.35) 

IN-J0290 16.7 90 15.5 120 

IN-V9367 35.3 120 35.3 120 

Data obtained from pp. 40-41 and Tables 7-10, pp. 60-67 of the study report. 
Nicosulfuron (PC 129008) MRID 49169703 

Page 19 of 30 

A transformation pathway was provided by the study author (Figure 23, p. 115). 

III. STUDY DEFICIENCIES AND REVIEWER’S COMMENTS 

1. The soil extraction procedures were not adequate to extract all identifiable [14C]residues in the 

soils. Unextracted radioactivity in the test soils incubated at 20oC increased to maximums of 

30.0-40.2% of the applied at 90 or 120 days posttreatment (Table 3, pp. 52-53; Table 4, pp. 54-

55; Table 6, pp. 58-59). Only the Day 120 Gross-Umstadt loam soil samples treated with 

[pyrimidine-2-14C]nicosulfuron were subjected to humic/fulvic extraction for further 

characterization of the unextracted residues (p. 28). At 120 days, fulvic acid was 25.0% of the 

applied, humic acid was 6.0%, and humin was 8.0% (p. 42); further characterization was not 

performed. For all of the test soils, the more aggressive extraction should have been done at 

more sampling intervals. 

2. Champenoux clay loam soil experiment conducted at 10°C was terminated at 120 days, at which 

time undegraded nicosulfuron comprised 47.1-57.2% of the applied radioactivity, accounting for 

>50% of the initial radioactivity (94.5-96.4% of the applied; Table 9, pp. 64-65). It is preferable 

that metabolism experiments are conducted for several intervals past the observed half-life, so 

that the pattern of decline of the parent compound and the patterns of formation and decline of 
Nicosulfuron (PC 129008) MRID 49169703 

Page 20 of 30 

the transformation products are clearly established. 

3. Information on the aerobic soil metabolism of nicosulfuron in three different soils is presented 

in this study. To satisfy OCSPP guidelines, information on aerobic metabolism in four different 

soil types is required. 

4. The study author incorrectly identified the Champenoux soil as a sandy loam using the USDA 

Soil Textural Classification System. The reviewer determined that this soil is a clay loam, and 

refers to it as such in this review. 

5. Single samples were collected for sample analysis at all sampling intervals. It is preferable for 

duplicate samples to be collected so that between replicate variability can be assessed. 

6. Complete descriptions of the unlabeled reference standards were not reported. Chemical names 

were not provided for the reference standards IN-69188 and IN-H9235. Also, the purity and lot 

number were not provided for the following reference standards: IN-GDC42, 

IN-77799, IN-69188, IN-H9235, and IN-HYY21. The purity was not provided for IN-37740. 

7. During the 20oC experiments, the incubation temperature was reported to be 20 ± 2C (p. 37). 

The study author reported that there were four deviations lasting up to seven hours. The 

temperature range was 22.9-27.6C. During the 10°C experiment, the incubation temperature 

was reported to be 10 ± 2C. The study author reported that there were three deviations lasting 

up to 1 hour. The temperature range was 12.7-13.6C. 

8. Storage stability analysis of a Day 0 soil extract from a soil sample treated with [pyridine-2-

14C]nicosulfuron and analyzed ca. 6 months after the initial extraction showed that nicosulfuron 

comprised >99% of the radioactivity (p. 44). 

9. In order to produce sufficient material for identification, additional samples were prepared and 

treated at 1 g a.i./g (pp. 19, 25). 

IV. REFERENCES 

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

Guidelines, OCSPP 835.4100, Aerobic Soil Metabolism. Office of Chemical Safety and 

Pollution Prevention, Washington, DC. EPA 712-C-08-016. 

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

Degradation Kinetics in Environmental Media. 
Nicosulfuron (PC 129008) MRID 49169703 

Page 21 of 30 

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

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Maximum %

PARENT

Nicosulfuron (DPXV9360; IN-V9360) IUPAC: 2-[(4,6- Dimethoxypyrimidin-2-

ylcarbamoyl)sulfamoyl]-N,Ndimethylnicotinamide CAS: 2-[[[[(4,6-Dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide CAS No.: 111991-09-4 Formula: C15

H18

N6O6S 

MW: 410.4 g/molSMILES: CN(C)C(=O)c1cccnc1S(=O)(=O)NC(=O)Nc2nc(OC)cc(OC)n2 

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 9

Clay loam 

(20°C) 9

Loam 

(20°C) 9

Clay loam 

(10°C) 9

MAJOR (>10%) TRANSFORMATION PRODUCTS 

IN-V9367 CAS: 2-(Aminosulfonyl)-N,Ndimethyl-3-pyridinecarboxamide 

CAS No.: 112006-75-4 Formula: C8H11

N3O3S 

MW: 229.25 g/molSMILES: CN(C)C(=O)c1cccnc1S(=O)(=O)N 

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 52

Clay loam 

(20°C) 72

Loam 

(20°C) 6

Clay loam 

(10°C) 35

IN-J0290 CAS: 4,6-Dimethoxy-2-

pyrimidinamine CAS No.: 36315-01-2 Formula: C6H9N3O2

MW: 155.15 g/molSMILES: [H]N([H])c1nc(cc(n1)OC)OC 

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 21

Clay loam 

(20°C) 48

Clay loam 

(10°C) 16
Nicosulfuron (PC 129008) MRID 49169703 

Page 22 of 30 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Maximum %

IN-HYY21 CAS: 2-[[[[Aminoiminomethyl) 

amino]carbonyl)amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamideFormula: C10

H14

N6O4S 

MW: 314.33 g/molSMILES: CN(C)C(=O)c1cccnc1S(=O)(=O)NC(=O)NC(=N)N 

O

N

H3C C H3

S

O

O

O

N H2N H

NH

NH

N

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 13

Clay loam 

(20°C) 4

Loam 

(20°C) 34

Unextractable residues

NA NA 

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 32

Clay loam 

(20°C) 30

Loam 

(20°C) 40

Clay loam 

(10°C) 19

MINOR (<10%) TRANSFORMATION PRODUCTS

IN-74427 CAS: 2-[(4,6-Dimethoxy-2-

pyrimidinyl)-amino]-N,N-dimethyl-3-pyridinecarboxamide Formula: C14

H17

N5O3

MW: 303.32 g/molSMILES: [H]N(c1c(cccn1)C(=O)N(C)C)c2nc(cc(n2)OC)OC 

N

H

O CH3O CH3

NN

N

O

N

H3CH3C

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 1.4

Clay loam 

(20°C) 2

IN-69188 IUPAC: 1-(4,6-Dimethoxypyrimidin2-yl)pyrido[2,3-d]pyrimidine-2,4-

dione Formula: C13

H11

N5O4

MW: 301.26 g/molSMILES: COc1cc(nc(n1)n2c3c(cccn3)c(=O)[nH]c2=O)OC 

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 2

Clay loam 

(20°C) 2
Nicosulfuron (PC 129008) MRID 49169703 

Page 23 of 30 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Maximum %

IN-37740 CAS: 2-[[(3,4-Dihydro-6-methoxy-4-

oxopyrimidin-2-yl]aminocarbonyl]aminosulfonyl]-N,N-dimethyl-3-pyridinecarboxamideFormula: C14

H16

N6O6S 

MW: 396.38 g/molSMILES: [H]n1c(=O)cc(nc1N([H])C(=O)N([H])S(=O)(=O)c2c(cccn2)C(=O)N(C)C)OC 

S

O

O

N

H

O

N

H

O CH3O

N

H

N

N

O

N

H3C

H3C

835.4100 

Aerobic soil 

metabolism 49169703 

Clay loam 

(20°C) 2

Loam 

(20°C) 5

IN-77799 CAS: 2-[(Aminocarbonyl) [4-

methoxy-6-(methyldioxy}-2-pyrimidinyl] amino]-N,N-dimethyl-3-pyridinecarboxamide Formula: C15

H18

N6O4

MW: 346.34 g/molSMILES: CN(C)C(=O)c1cccnc1N(c2nc(cc(n2)OC)OC)C(=O)N 

835.4100 

Aerobic soil 

metabolism 49169703 Clay loam (20°C) 3

IN-GDC42 CAS: 2-[[[[(Aminocarbonyl)amino] 

carbonyl]amino]sulfonyl]-N,Ndimethyl-3-pyridinecarboxamide Formula: C10

H13

N5O5S 

MW: 315.3 g/molSMILES: CN(C)C(=O)c1cccnc1S(=O)(=O)NC(=O)NC(=O)N 

N OC H3

H3C

S

O

O

N H2

O

HNHN

O

N

835.4100 

Aerobic soil 

metabolism 49169703 Loam (20°C) 7

Carbon dioxide IUPAC: Carbon dioxide 

Formula: CO2

MW: 44 g/molSMILES: C(=O)=O 

O

C

O

835.4100 

Aerobic soil 

metabolism 49169703 

Sandy loam 

(20°C) 9

Clay loam 

(20°C) 3

Loam 

(20°C) 5

Clay loam 

(10°C) 0
Nicosulfuron (PC 129008) MRID 49169703 

Page 24 of 30 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Maximum %

REFERENCE COMPOUNDS NOT IDENTIFIED 

IN-64554 CAS: Isothiaxolo[5,4-B]pyridin3(2H}-one,1,1-dioxide 

CAS No.: 138417-40-0 Formula: C6H4N2O3S 

MW: 184.17 g/molSMILES: c1cc2c(nc1)S(=O)(=O)NC2=O 

835.4100 

Aerobic soil 

metabolism 49169703 NA 

IN-W9807 CAS: 2-[[(4,6-Dimethoxypyrimidin2-yl) 

aminocarbonyl]arninosulfonyl]-Nmethyl-3-pyridinecarboxamide Formula: C14

H16

N6O6S 

MW: 396.38 g/molSMILES: [H]N(C)C(=O)c1cccnc1S(=O)(=O)N([H])C(=O)N([H])c2nc(cc(n2)OC)OC

S

O

O

N

H

O

N

H

O CH3O CH3

NN

N

O

N

H3C

H

835.4100 

Aerobic soil 

metabolism 49169703 NA 

IN-H1043 CAS: 2-Amino-6-hydroxy-4(1H)-

pyrimidinone CAS No.: 56-09-7 Formula: C4H5N3O2

MW: 127.1 g/molSMILES: c1c(nc(nc1O)N)O 

835.4100 

Aerobic soil 

metabolism 49169703 NA 

IN-H9235 IUPAC: 2-Amino-6-methoxypyrimidin-4-ol 

Formula: C5H7N3O2

MW: 141.13 g/molSMILES: [H]N([H])c1nc(cc(n1)OC)O 

835.4100 

Aerobic soil 

metabolism 49169703 NA 

A AR means “applied radioactivity”. MW means “molecular weight”. NA means “not applicable”. 
Nicosulfuron (PC 129008) MRID 49169703 

Page 25 of 30 
Nicosulfuron (PC 129008) MRID 49169703 

Page 26 of 30 

Attachment 2: Statistics Spreadsheets and Graph 

Chemical: Nicosulfuron

MRID: 

PC: 

Guideline: 835.4100

Aerobic metabolism of Nicosulfuron in sandy loam at 20°C

Days % AR

0 91.0

0 96.9

3 97.6

3 83.9

7 83.2

7 88.0

14 67.1

14 70.8

21 68.7

21 64.4

30 56.1

30 66.3

45 41.7

45 58.4

62 40.6

62 48.3

90 29.0

90 35.7

120 22.2

120 34.5

49126703

129008

Data obtained from Table 7, pp. 60-61 of the study report.

Aerobic metabolism of Nicosulfuron in sandy loam at 20°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 90

 90

 120

 120

91.0

96.9

97.6

83.9

83.2

88.0

67.1

70.8

68.7

64.4

56.1

66.3

41.7

58.4

40.6

48.3

29.0

35.7

22.2

34.5

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE -10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 20 40 60 80 100

DT50 DT90 

2 C0 Parameters

SFO 59.1 196 5.2 90 k  0.0117

DFOP 51.4 254 3 95.4 f  0.27k0  0.0605k1  0.00784

IORE 50.2 479 2.9 94.9 N  2.05k  0.00017

SC

SSFO

Slowt1 2

tRIORE

 628

 784

88.4

 144
Nicosulfuron (PC 129008) MRID 49169703 

Page 27 of 30 

Aerobic metabolism of Nicosulfuron in clay loam soil at 20°C

Days % AR

0 94.9

0 94.3

3 73.6

3 81.2

7 66.5

7 74.9

14 46.0

14 47.7

21 35.8

21 41.7

30 32.5

30 31.0

45 21.1

45 22.0

62 15.4

62 15.5

90 8.2

90 10.6

120 4.6

120 5.8

Data obtained from Table 8, pp. 62-63 of the study report.

Aerobic metabolism of Nicosulfuron in clay loam soil at 20°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 90

 90

 120

 120

94.9

94.3

73.6

81.2

66.5

74.9

46.0

47.7

35.8

41.7

32.5

31.0

21.1

22.0

15.4

15.5

8.20

10.6

4.60

5.80

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE -5

0

5

-5

0

5

-5

0

5

0 20 40 60 80 100120

DT50 DT90 

2 C0 Parameters

SFO 19.8 65.8 8.7 88.7 k  0.035

DFOP 15.5 89.5 4.2 94 f  0.5k0  0.0909k1  0.018

IORE 15.8 91.9 4.2 93.8 N  1.6k  0.0035

SC

SSFO

Slowt1 2

tRIORE

 199

 485

38.5

27.7

Aerobic metabolism of Nicosulfuron in loam soil at 20°C

Days % AR

0 96.5

0 98.8

3 84.1

3 85.2

7 72.9

7 73.1

14 56.8

14 54.4

21 44.7

21 44.1

30 33.5

30 33.6

45 22.0

45 27.2

62 14.7

62 14.6

76 9.3

76 10.2

90 7.7

90 8.3

120 4.8

120 5.2

Data obtained from Table 10, pp. 66-67 of the study report.

Aerobic metabolism of Nicosulfuron in loam soil at 20°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 76

 76

 90

 90

 120

 120

96.5

98.8

84.1

85.2

72.9

73.1

56.8

54.4

44.7

44.1

33.5

33.6

22.0

27.2

14.7

14.6

9.30

10.2

7.70

8.30

4.80

5.20

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

-6

-4

-2

0

2

4

6

0 20 40 60 80 100

DT50 DT90 

2 C0 Parameters

SFO 21.2 70.4 5.3 93.6 k  0.0327

DFOP 18.1 81 1.7 97.5 f  0.342k0  0.0894k1  0.0233

IORE 18.4 82.7 1.9 96.9 N  1.35k  0.00865

SC

SSFO

Slowt1 2

tRIORE

43.9

 180

29.7

24.9
Nicosulfuron (PC 129008) MRID 49169703 

Page 28 of 30 

Aerobic metabolism of Nicosulfuron in clay loam soil at 10°C

Days % AR

0 96.4

0 94.5

3 91.1

3 92.4

7 87.7

7 89.0

14 78.3

14 92.8

21 81.4

21 81.9

30 72.5

30 76.3

45 67.5

45 69.8

62 62.7

62 67.8

90 52.7

90 59.7

120 47.1

120 57.2

Data obtained from Table 9, pp. 64-65 of the study report.

Aerobic metabolism of Nicosulfuron in clay loam soil at 10°C

Days% AR

0

0

 3

 3

 7

 7

 14

 14

 21

 21

 30

 30

 45

 45

 62

 62

 90

 90

 120

 120

96.4

94.5

91.1

92.4

87.7

89.0

78.3

92.8

81.4

81.9

72.5

76.3

67.5

69.8

62.7

67.8

52.7

59.7

47.1

57.2

0 20 40 60 80 100 120

0

20

40

60

80

Time

Concentration

SFO

DFOP

IORE

-10

-5

0

5

10

-10

-5

0

5

10

-10

-5

0

5

10

0 20 40 60 80 100

DT50 DT90 

2 C0 Parameters

SFO 128 425 2.5 92 k  0.00542

DFOP 156 1019 1.1 94.8 f 0.351k0  0.0214k1  0.00184

IORE 150 4051 1.1 95 N  2.85k  2.02e-06

SC

SSFO

Slowt1 2

tRIORE

 259

 322

 378

1.22e+03
Nicosulfuron (PC 129008) MRID 49169703 

Page 29 of 30 

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) 
Nicosulfuron (PC 129008) MRID 49169703 

Page 30 of 30 

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