Test Material: Nicosulfuron 

 

MRID 48790905 

 

Title: Allan, J. 2012. Anaerobic aquatic metabolism of 14C-nicosulfuron (DPXV9360) in two water/sediment systems 

 

EPA PC Code: 129008 

 

OCSPP Guideline: 835.4400 

For Cambridge Environmental 

 

Primary Reviewer: Lynne Binari Signature: 

Date: 10/23/12 

 

Secondary Reviewer: Kathleen Ferguson Signature: 

Date: 10/23/12 

 

QC/QA Manager: Joan Gaidos Signature: 

Date: 10/23/12 

Nicosulfuron (PC 129008) MRID 48790905 

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analyzed), a maximum of 8.2% at 14 days and 1.5-1.6% at 102 days. In the silt loam system, 

nicosulfuron in the water column decreased from 95.5-100.3% at day 0 to 43.1-47.6% at 102 days, 

while nicosulfuron in the sediment was 3.8-4.9% (maximum 4.9%) at day 0 and 2.1-2.5% at 102 

days. 

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

in Table 1. Nicosulfuron transformation rates and product profiles were similar between the two 

sediment types. 

In the sand sediment (combined labels), extractable radioactivity increased from 0.6-1.6% of the 

applied at day 0 to maximums of 10.3-10.4% at 14 days (pyridine label) and 80 days (pyrimidine 

label) and was 8.4-9.4% at 102 days, while unextracted radioactivity increased from 0.0% (n = 2) at 

day 0 to 17.8-20.2% at study termination. At study termination, ≤0.2%, 6.7-7.2% and 6.4-8.2% of 

the applied was associated with the fulvic acids, humic acids and humin, respectively. Total evolved 

14CO2 amounted to 2.0-4.6% of the applied. 

In the silt loam sediment (combined labels), extractable radioactivity increased from 0.6-0.7% of 

the applied at day 0 to maximums of 9.1-9.8% at 80 days and was 7.0-7.8% at 102 days, while 

unextracted radioactivity increased from 0.1-0.2% at day 0 to 27.0-28.9% at study termination. At 

study termination, 0.1% (n = 2), 9.7-10.4% and 10.7-14.8% of the applied was associated with the 

fulvic acids, humic acids and humin, respectively. Total evolved 14CO2 amounted to 0.1-0.5% of the 

applied. 

Table 1. Results Synopsis: Anaerobic Aquatic Metabolism of Nicosulfuron in the Total System 

Total System1 

Observed 

DT50

(days) 

Calculated 

Half-life 

(days) 

Model 

Parameters and 

Statistics2 

Transformation Products Common Name 

(maximum % of applied observed, associated interval)3 

Major Minor 

Georgia natural 

water:sand sediment 

system (20°C, water 

pH 7.6, sediment pH 

7.6)

ca. 101 101 

C0 = 101 

k = 0.00685 

Sc = 322 

SSFO = 287 

r

2

 = -- 

(SFO)

IN-37740 (13.9%, 80 days) 

Unextracted residues (pyridine 

label 20.2%, pyrimidine label 

17.8%, 102 days) 

IN-R5Q09 (6.6%, 102 

days) 

IN-V9367 (4.8%, 102 

days)

CO2 (pyridine label 2.0%, 

pyrimidine label 4.6%, 

102 days) 

Missouri natural 

water:silt loam 

sediment system (20°C, 

water pH 7.9, sediment 

pH 7.8)

ca. 95 92.3 

C0 = 102 

k = 0.00751 

Sc = 213 

SSFO = 179 

r

2

 = -- 

(SFO) 

IN-37740 (13.0%, 80 days) 

Unextracted residues (pyridine 

label 28.9%, pyrimidine label 

27.0%, 102 days) 

IN-R5Q09 (5.8%, 102 

days) 

IN-V9367 (4.2%, 102 

days)

CO2 (pyridine label 0.5%, 

pyrimidine label 0.1%, 

102 days) 

1 Sampling site not described (pond, lake, river, ditch, rice paddy, etc.). 

2 Calculated half-lives and model parameters for the best fit kinetics models in accordance with the NAFTA kinetics 

guidance (USEPA, 2011); -- = not calculated; SFO = Simple First Order. 

3 IN-37740 and IN-R5Q09 contained both pyridine and pyrimidine labels; IN-V9367 contained pyridine label.
Nicosulfuron (PC 129008) MRID 48790905 

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I. Materials and Methods 

A. Materials [Pyridine-2-14C]- and [pyrimidine-2-14C]-labeled nicosulfuron (p. 18). 

1. Test Materials: 

[Pyridine-2-14C]-label 

Specific activity: 42.71 μCi/mg N

O CH3

O CH3

N

N

H

O

N

H

S

O

O

N

N

H3C

H3C

O

*

Radiochemical purity: >95% (pp. 18, 33; Figure 5A, p. 

67) 

Chemical purity: Not reported 

Lot/Batch No.: 3638105 

[Pyrimidine-2-14C]-label 

N

N

O CH3

O CH3

N

N

H

O

N

H

S

O

O

N

H3C

H3C

O

*

Specific activity: 42.67 μCi/mg 

Radiochemical purity: >98% (pp. 18, 33; Figure 5B, p. 68)

Chemical purity: Not reported 

Lot/Batch No.: 3638127 

Solubility in water: 7.4 g/L at 25oC (p. 18). 

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

Table 2. Reference Compounds1 

Applicant’s Code 

Name (synonyms) Chemical Name (CAS) Purity 

(%) Lot No. 

Nicosulfuron 

(DPX-V9360) 

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

amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide 98.3 E105819-003 

IN-V9367 2-(Aminosulfonyl)-N,N-dimethyl-3-pyridinecarboxamide 99.7 005 

IN-64554 Isothiaxolo[5,4-B]pyridin-3(2H)-one,1,1-dioxide 99.3 D100082-298C

IN-37740 2-[[(3,4-Dihydro-6-methoxy-4-oxopyrimidin-2-yl]aminocarbonyl]aminosulfonyl]-N,N-dimethyl-3-pyridinecarboxamide 98.1 E106951-071B

IN-J0290 4,6-Dimethoxy-2-pyrimidinamine 99.9 9964-098 

IN-GDC42 2[[[[(Aminocarbonyl)amino]carbonyl]amino]sulfonyl]-N,Ndimethyl-3-pyridinecarboxamide 96.3 001 

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

pyrimidinyl]amino]-N,N-dimethyl-3-pyridinecarboxamide 98.7 E105318-116 

IN-HYY21 2-[[[[(Aminoiminomethyl)amino]carbonyl]amino]sulfonyl]-

N,N-dimethyl-3-pyridinecarboxamide 90.3 004 

Data obtained from p. 19; Figure 1, pp. 58-60 of the study report. Nicosulfuron CAS name not provided in study report 

(pp. 17-18; Figure 1, p. 58); CAS name obtained from file Nicosulfuron structures[1].doc. 

1 Reference compounds provided by DuPont (p. 19). 
Nicosulfuron (PC 129008) MRID 48790905 

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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 Tift Boonville 

Geographic location 

Chula, Tift County, Georgia, 

U.S.A.; sampling site not 

described 

Boonville, Cooper County, 

Missouri, U.S.A.; sampling site 

not described 

Pesticide use history at the collection site Not reported 

Collection date Not reported 

Collection 

procedures 

Water: Not reported 

Sediment: Not reported 

Storage conditions Water: Not reported 

Sediment: Stored at ca. 4oC in darkness; no additional details were provided 

Storage length Less than one month 

Preparation 

Water: 

Water and sediment ca. 2-mm sieved 

Sediment: 

Data obtained from pp. 20, 32 of the study report. 

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

Parameter 

(unit) 

Field Sampling/Post 

Handling 

Stage of Test Procedure1

Prior to Test2 During Test End of Test 

Water 

Temperature (oC) -- 

pH 7.6 7.905, 7.790 7.422-8.607 8.478, 8.664 

TOC (mg/L) -- -- -- 

O2 (mg/L) -- 0.48, 0.33 0.08-1.13 0.21, 0.14 

Redox potential(mV) -189.8, -176.3 -225.1 to -36.2 -219.1, -122.7 

Sediment 

Sampling Depth (cm) Not reported 

pH 7.63 7.195, 7.140 7.087-7.356 7.465, 7.534 

Soil Texture (USDA) Sand 

Particle Size Distribution 

94% sand (2000-50 μm) 

4% silt (50-2 μm) 

2% clay (<2 μm) 

TOC (mg/L) -- -- 

Organic matter (%, Walkley Black) 1.3 

Organic carbon (%)4 0.756 

CEC (meq/100 g) 5.0 

Soil moisture 

(%) at 

1/3 bar: 4.7 

15 bar: 2.9 

Bulk density, disturbed (g/cc) 1.22 

Microbial biomass (μg/g dry wt.)5 92.9 25.1 

Redox potential (mV) -223.4, -220.3 -272.2 to -133.2 -231.6, -196.1 

Data obtained from p. 32; Tables 1A-B, pp. 40-41; Table 4A, p. 45 of the study report. Soil texture confirmed by the 

reviewer using USDA-NRCS technical support tools. 

-- = Not reported. 

1 System parameters (pH, oxygen concentration, redox potential) measured in treated systems at each collection interval 

(p. 25; Table 4A, p. 45). Measurements taken using a WTW Multi 3430 IDS (intelligent digital sensor); for redox 

potential, reference electrode was not specified (p. 20). 

2 Day 0 posttreatment interval. 

3 In 1:1 soil:water ratio (Table 1A, p. 40). 
Nicosulfuron (PC 129008) MRID 48790905 

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4 Percent organic carbon determined by the study author using the following formula: organic carbon (%) = organic 

matter (%) ÷ 1.72 (Table 1A, p. 40). 

5 Fumigation and extraction method (pp. 21, 32). Measured in sediment from untreated test systems (p. 22).

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

Parameter 

(unit) 

Field Sampling/Post 

Handling 

Stage of Test Procedure1

Prior to Test2 During Test End of Test 

Water 

Temperature (oC) -- 

pH 7.9 7.415, 7.680 7.294-8.106 8.153, 8.248 

TOC (mg/L) -- -- -- 

O2 (mg/L) -- 0.33, 0.47 0.00-0.53 0.14, 0.13 

Redox potential(mV) -161.0, -160.9 -227.9 to -146.6 -240.6, -245.6 

Sediment 

Sampling Depth (cm) Not reported 

pH 7.83 7.229, 7.230 7.134-7.341 7.336, 7.332 

Soil Texture (USDA) Silt Loam 

Particle Size Distribution 

18% sand (2000-50 μm) 

56% silt (50-2 μm) 

26% clay (<2 μm) 

TOC (mg/L) -- -- 

Organic matter (%, Walkley Black) 3.2 

Organic carbon (%)4 1.86 

CEC (meq/100 g) 15.3 

Soil moisture 

(%) at 

1/3 bar: 33.4 

15 bar: 17.2 

Bulk density, disturbed (g/cc) 0.93 

Microbial biomass (μg/g dry wt.)5 51.6 42.9 

Redox potential (mV) -246.9, -236.3 -254.1 to -189.9 -239.0, -249.5 

Data obtained from p. 32; Tables 1A-B, pp. 40-41; Table 5A, p. 46 of the study report. Soil texture confirmed by the 

reviewer using USDA-NRCS technical support tools. 

-- = Not reported. 

1 System parameters (pH, oxygen concentration, redox potential) measured in treated systems at each collection interval 

(p. 25; Table 5A, p. 46). Measurements taken using a WTW Multi 3430 IDS (intelligent digital sensor); for redox 

potential, reference electrode was not specified (p. 20). 

2 Day 0 posttreatment interval. 

3 In 1:1 soil:water ratio (Table 1A, p. 40). 

4 Percent organic carbon determined by the study author using the following formula: organic carbon (%) = organic 

matter (%) ÷ 1.72 (Table 1A, p. 40). 

5 Fumigation and extraction method (pp. 21, 32). Measured in sediment from untreated test systems (p. 22).
Nicosulfuron (PC 129008) MRID 48790905 

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B. Study Design

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

Table 5. Experimental Design 

Experimental Design Tift Boonville 

Duration of the test 246 days 

Water: 

Type and size of filter used Not reported. 

Amount of sediment and water per treatment: 

Water 411 g total; 355 mL added + ca. 

56 g associated with sediment 

422 g total; 355 mL added + ca. 

67 g associated with sediment. 

Sediment 191 g wet wt., ca. 135 g dry wt. 143 g wet wt., ca. 76.1 g dry wt. 

Water/sediment ratio Total Water:Dry wt. 3:1 (411 g:135 g dry wt.) 5.5:1 (422 g:76.1 g dry wt.) 

Water added:Wet wt. 1.9:1 (355 mL:191 g wet wt.) 2.5:1 (355 mL:143 g wet wt.) 

Application rates: 

Nominal 0.3 mg a.i./L 

Actual1 0.255 mg/L (0.105 mg in 411 g 

total water) 

0.249 mg/L (0.105 mg in 422 g 

total water) 

Number of replicates:

Control, if used Sterile controls were not used. 

Treated 

Per system and label type, eleven water-sediment systems were treated 

to allow for a single system per label/system type at each of eight 

sampling intervals, plus reserves. 

Test apparatus: 

Type/material/volume 

Nalgene bottles (500-mL), containing the water-sediment system, 

connected in series (sample train per system/label type) to a continuous 

flow-through (humidified nitrogen, flow rate not reported) volatiles 

trapping system (Figure 2, p. 61). 

Details of traps for CO2 and organic volatile, if 

any

In sequence as follows: Supelco ORBO-32 tube (one trap) to collect 

organic volatiles and 1M KOH solution (two traps) to collect CO2; 

trapping solution volumes not reported. 

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

Identity and final concentration (based on 

water volume) of co-solvent 

Acetonitrile:0.01M ammonium acetate (50:50, v:v); 0.1% ACN by 

volume (793-802 μL of 50:50 test solution/411-422 g total water). 

Test material application method: 

Volume of the test solution 

used/treatment 

Pyridine label 793 μL 

Pyrimidine label 802 μL 

Application method (i.e., mixed/not mixed) Applied just below water layer surface using a 100-1,000-μL pipette 

Any indication of the test material adsorbing 

to the walls of the test apparatus? 

None; 99.6-101.6% of the applied recovered in water layers at day 0 

posttreatment 

Microbial biomass/population of control units: Sterile controls were not used. 

Water -- 

Sediment -- 

Microbial biomass/population of treated: Not determined in treated systems 

Water -- 

Sediment -- 

Experimental conditions: 

Temperature 20 ± 2C 

Continuous darkness (yes/no) Yes 

Other details (if any) The water:sediment systems were acclimated to test conditions for 7 
Nicosulfuron (PC 129008) MRID 48790905 

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Experimental Design Tift Boonville 

days prior to treatment; anaerobic conditions were defined as a 

dissolved oxygen content of <2 mg O2/L. 

Additional untreated water:sediment systems were prepared and 

maintained for microbial biomass (six systems per sediment type) and 

system parameter (pH, oxygen concentration, redox potential; two 

"control" systems per sediment type) determinations. 

Two months after initiation of the definitive experiment, additional 

systems were treated at a 10x rate (1.05 mg a.i./system) for both labels 

and incubated as described above; no additional details were provided. 

The nominal test application rate of 0.3 mg a.i./L used in this study 

was selected to allow for an adequate amount of material to follow the 

degradation of nicosulfuron. No comparison to the maximum field use 

rate for nicosulfuron was provided. 

Data obtained from pp. 17-18, 21-24, 26; Table 2, p. 42; Table 4B, p. 45; Table 5B, p. 46; Tables 6-7, pp. 47-48; Figure 

2, p. 61 of the study report. 

1 For both labels 0.105 mg/system applied, based on 793 μL of 0.1325 mg/mL [pyridine-2-14C]nicosulfuron test 

solution, and 802 μL of 0.1310 mg/mL [pyrimidine-2-14C]nicosulfuron test solution (p. 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) 0, 3, 7, 14, 31, 60, 80 and 102 days 

Sampling method Per system and label type, a single sample was collected at each 

sampling interval 

Method of collection of CO2 and organic 

volatile compounds 

Volatiles traps were collected and replaced at each sampling interval 

after day 0 

Sampling Intervals/Times 

Redox potential in water layer 

Measured in treated systems collected at each sampling interval. 

Probes were placed in the water phase or just below surface of 

sediment. 

Dissolved oxygen in water layer 

pH in water layer 

Redox potential in sediment 

pH in sediment 

Other details, if any 

The water layer was decanted and sediments extracted the day of 

collection. Water layers were filtered and "typically" analyzed within 

24 hours of collection. Sediment extracts were "typically" analyzed 

by HPLC within one week of collection. Following LSC analysis, 

water layers and sediment extracts were stored frozen. 

10x rate systems: Aliquots (10 mL) were taken from the water layers 

of the [pyridine-2-14C]-label treated sand sediment (Tift) and the 

[pyrimidine-2-14C]-label treated silt loam sediment (Boonville) 

systems at 79 days posttreatment. 

Data obtained from pp. 24, 37; Tables 6-7, pp. 47-48 of the study report. 
Nicosulfuron (PC 129008) MRID 48790905 

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3. Analytical Procedures:

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

decanting (p. 25). 

Extraction/Clean Up/Concentration Methods: Water layer. An aliquot (ca. 5 mL) of the water 

layer was filtered (0.45-μm nylon syringe filter), then triplicate aliquots (1 mL) of unfiltered and 

filtered water were analyzed for total radioactivity by LSC to confirm post-filtration recoveries of 

90-110% (p. 25; Appendix 1, p. 105). Filtered water samples were analyzed directly using HPLC. 

Sediment was extracted three times with acetone:0.1M ammonium carbonate (80:20, v:v) via 

shaking (Eberbach reciprocating shaker, "low speed") for 30 minutes/extraction; extraction solvent 

volumes were 160 mL (pp. 20, 25). Sediment and extract were separated by centrifugation (ca. 

4,800 rpm, 10 minutes). Extracts were combined, brought to volume (ca. 480 mL) with extraction 

solvent, and aliquots (1 mL, replicates not reported) analyzed by LSC (p. 25; Appendix 1, p. 105). 

An aliquot (50-100 mL) was concentrated to dryness (method not specified), with the residues 

reconstituted in 0.1% formic acid:methanol (95:5, v:v, 5 mL), filtered (0.45-μm) and analyzed by 

HPLC (Figure 3, p. 62). 

Determination of Unextracted Residues: Extracted sediment was dried under a nitrogen stream, 

homogenized (method not specified), then triplicate aliquots (ca. 0.5g) were analyzed for total 

radioactivity by LSC following combustion (p. 26; Appendix 1, p. 105). Oxidizer efficiency was 

reported as 95-105% (p. 27). 

Organic matter fractionation. Day 102 extracted sediment was further characterized using standard 

organic matter fractionation techniques (p. 26). Fulvic acid and humic acid fractions were analyzed 

for total radioactivity by LSC, and the humin by LSC following combustion. 

Determination of Volatile Residues: Triplicate aliquots (1 mL) of the KOH trapping solutions 

were analyzed for total radioactivity using LSC (p. 24; Appendix 1, p. 106). The ORBO-32 tubes 

were not analyzed (p. 26). 

Total Radioactivity Measurement: Total 14Cresidues were determined by summing the 

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

trapping solutions (pp. 29-30). 

Derivatization Method A derivatization method was not employed. 

Identification and Quantification of Parent Compound: Water layer and sediment extract 

samples were analyzed by HPLC (Agilent Systems) using a Phenomenex Luna C18(2) column (4.6 

x 150 mm, 5 μm) eluted with a gradient mobile phase of (A) 0.1% formic acid and (B) methanol 

(pp. 27-28). The eluent was monitored with radioactivity and UV (254 nm) detectors. Components 

were quantified and column recoveries determined by fraction collection (interval not specified) and 

LSC analysis (p. 27). Column recoveries were reported as within ca. 90-110% for all samples (p. 

33). Parent [14C]nicosulfuron was identified by comparison to the relative retention time of 

unlabeled reference standard (p. 27; Figure 4A, p. 63; Figures 8A-11G, pp. 73-88). 
Nicosulfuron (PC 129008) MRID 48790905 

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Identification of [14C]nicosulfuron in the water layer of 10x rate systems was confirmed against 

reference standard by LC/MS/MS-ESI+ (electrospray ionization, positive ion mode, m/z 411) using 

a Phenomenex Luna C18 column (4.6 x 150 mm, 5 μm) eluted with a gradient mobile phase of (A) 

0.1% aqueous formic acid and (B) acetonitrile (pp. 28-29, 36; Figures 12A-12C, pp. 89-91). 

Identification and Quantification of Transformation Products: Transformation products were 

separated and quantified using HPLC as described for parent (pp. 27-28; Figures 4B-4H, pp. 63-66; 

Figures 8A-11G, pp. 73-88). Identification of product [14C]IN-37740 (m/z 397) in the water layer of 

10x rate systems was confirmed against reference standard by LC/MS/MS-ESI+

 as described above 

(pp. 28-29, 36; Figures 12D-12F, pp. 92-94). Also using LC/MS/MS-ESI+, a structure for product 

[

14C]IN-R5Q09 (m/z 383) was proposed based on molecular weight and fragmentation pattern (p. 

36; Figures 12G-12J, pp. 95-98). 

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

Table 7 summarizes limits of detection and quantitation as determined using the method of Currie 

(pp. 31, 39). 

Table 7. Limits of Detection (LOD) and Quantitation (LOQ), Expressed as Percentage of the 

Applied Radioactivity (Combined Labels) 

Sample Type LOD LOQ 

HPLC analyses 

Aqueous 0.075-0.077 0.31 

Organic 0.010 0.041 

LSC analyses 

KOH trap 0.0047 0.017 

Aqueous layer 0.046 0.18 

Organic extracts 0.061-0.062 0.23-0.24 

Soil combustions Sand (Tift): 0.054-0.055 0.20 

Silt Loam (Boonville): 0.039-0.040 0.14 

Data obtained from Table 3, p. 44; Appendix 3, pp. 129-130 of the study report. 

II. Results and Discussion 

A. Data: 

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

Tables 8a and 8b. The incubation temperature was reportedly maintained throughout the 

experiment (p. 32). System parameters (redox potential, dissolved oxygen, pH) measured in the 

[

14C]nicosulfuron treated systems were comparable to untreated ("control") systems (Tables 4A-5B, 

pp. 45-46). For the treated systems (sand and silt loam), dissolved oxygen was detected at nearly all 

intervals during the 102-day study, but pE + pH was <12 at all intervals for the water column and 

sediment (DER Attachment 2). Microbial biomass determinations of sediment from untreated 

systems indicated both sediments were viable at initiation and termination (pp. 26, 32). 

Sand sediment (Tift) system (combined labels). In the water column, redox potential, dissolved 

oxygen and pH were -189.8 to -176.3 mV, 0.33-0.48 mg/L and 7.790-7.905, respectively, at day 0 

posttreatment and -219.1 to -122.7 mV, 0.14-0.21 and 8.478-8.664, respectively at 102 days (Table 

4A, p. 45). In the sediment, redox potential and pH were -223.4 to -220.3 mV and 7.140-7.195, 

respectively, at day 0 and -231.6 to -196.1 mV and 7.465-7.534, respectively, at study termination. 
Nicosulfuron (PC 129008) MRID 48790905 

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Silt loam sediment (Boonville) system (combined labels). In the water column, redox potential, 

dissolved oxygen and pH were -161.0 to -160.9 mV, 0.33-0.47 mg/L and 7.415-7.680, respectively, 

at day 0 posttreatment and -245.6 to -240.6 mV, 0.13-0.14 and 8.153-8.248, respectively at 102 

days (Table 5A, p. 46). In the sediment, redox potential and pH were -246.9 to -236.3 mV and 

7.229-7230, respectively, at day 0 and -249.5 to -239.0 mV and 7.332-7.336, respectively, at study 

termination. 

B. Mass Balance: 

In the sand sediment (Tift) system (combined labels), recoveries ranged from 101.2 to 106.9% of 

the applied (Table 6, p. 47). Recoveries of total residues did not decrease over time and were within 

guideline criteria. In the water column nicosulfuron decreased from 95.2-97.1% of the applied at 

day 0 to 43.9-52.4% at 102 days (Table 8A, p. 49; Table 9A, p. 51). In the sediment nicosulfuron 

was 2.7-4.4% of the applied at 3 days (day 0 not analyzed), a maximum of 8.2% at 14 days, and 

1.5-1.6% at 102 days. 

In the silt loam sediment (Boonville) system (combined labels), recoveries ranged from 100.6 to 

105.6% of the applied (Table 7, p. 48). Recoveries of total residues did not decrease over time and 

were within guideline criteria. In the water column nicosulfuron decreased from 95.5-100.3% of the 

applied at day 0 to 43.1-47.6% at 102 days (Table 10A, p. 53; Table 11A, p. 55). In the sediment 

nicosulfuron was 3.8-4.9% of the applied at 3 days (day 0 not analyzed, maximum 4.9%) and 2.1-

2.5% at 102 days. 

C. Bound and Extractable Residues:

In the sand sediment (Tift), extractable radioactivity (combined labels) increased from 0.6-1.6% of 

the applied at day 0 to maximums of 10.3-10.4% at 14 days (pyridine label, "PY") and 80 days 

(pyrimidine label, "MD") and was 8.4-9.4% at 102 days (Table 6, p. 47). Unextracted radioactivity 

increased from 0.0% (n = 2) of the applied at day 0 to maximums of 17.8-20.2% at study 

termination. Organic matter fractionation (102 days) found 0.0-0.2%, 6.7-7.2% and 6.4-8.2% of the 

applied associated with the fulvic acids, humic acids and humin, respectively (Table 12A, p. 57). 

 

In the silt loam sediment (Boonville), extractable radioactivity (combined labels) increased from 

0.6-0.7% of the applied at day 0 to maximums of 9.1-9.8% at 80 days and was 7.0-7.8% at 102 days 

(Table 7, p. 48). Unextracted radioactivity increased from 0.1-0.2% of the applied at day 0 to 

maximums of 27.0-28.9% at study termination. Organic matter fractionation (102 days) found 0.1% 

(n = 2), 9.7-10.4% and 10.7-14.8% of the applied associated with the fulvic acids, humic acids and 

humin, respectively (Table 12B, p. 57). 

D. Volatilization:

For the pyridine and pyrimidine labels at study termination, volatile 14CO2 totaled 2.0% and 4.6% of 

the applied, respectively, in the sand sediment (Tift) system and 0.5% and 0.1%, respectively, in the 

silt loam sediment (Boonville) system (Tables 6-7, pp. 47-48). The ORBO tubes were not analyzed 

for other volatile compounds (p. 26). 
Table 8a. Transformation of Nicosulfuron, Expressed as Percentage of the Applied Radioactivity, in Anaerobic 

Sediment System1

Sampling Interval (days) 0 3 7 14 31 60 Replicate Number2 PY MD PY MD PY MD PY MD PY MD PY MD PNicosulfuron 97.1 95.2 101.0 100.4 96.9 99.3 89.7 98.0 80.5 91.6 62.5 66.0 5IN-37740 0.0 0.0 0.0 0.0 0.0 0.0 0.9 0.0 8.8 4.6 13.3 13.1 1IN-R5Q093 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.1 2.0 5IN-V9367 0.0 n.a. 0.0 n.a. 0.0 n.a. 0.9 n.a. 2.4 n.a. 2.3 n.a. 4Total other unknowns4 2.5 5.5 2.8 0.9 4.9 1.4 9.6 1.2 6.3 1.8 6.8 4.4 7Uncharacterized extracted residues5 1.6 0.6 Extracted residues 1.6 0.6 4.5 2.8 3.8 2.2 10.3 2.8 7.1 5.5 8.9 8.4 9Unextracted residues 0.0 0.0 0.1 0.1 0.4 0.1 1.3 0.5 4.0 1.8 11.0 10.4 1

Fulvic acids 

n.p. 

Humic acids Humin 

CO26 n.p. n.p. 1.9 4.5 1.9 4.5 2.0 4.5 2.0 4.5 2.0 4.5 2Other volatile compounds ORBO tubes were not analyzed. Mass balance 101.2 101.3 105.8 105.9 104.1 105.4 103.5 104.9 104.4 105.5 103.0 105.0 10

Data obtained from Table 6, p. 47; Table 8A, p. 49; Table 9A, p. 51; Table 12A, p. 57 of the study report. n.a. = Not applicable. n.p. = Not performed. 1 Sampling site not described (pond, lake, river, ditch, rice paddy, etc.). 2 PY = pyridine label, MD = pyrimidine label. 3 Tentative identification based on LC/MS/MS molecular weight and fragmentation pattern (p. 36). 4 Comprised of up to seventeen components, with no individual component >5.1% of applied in total system (Table 8A, p. 49; Table 9A, p. 

80). 

5 Sediment extracts not analyzed by HPLC. 6 Per label, all samples were connected to the same set of volatile traps. 
Nicosulfuron (PC 129008) MRID 48790905 

Page 13 of 28 

Table 8b. Transformation of Nicosulfuron, Expressed as Percentage of the Applied Radioactivity, in Anaerobi

Loam Sediment System1

Sampling Interval (days) 0 3 7 14 31 60 Replicate Number2 PY MD PY MD PY MD PY MD PY MD PY MD PNicosulfuron 95.5 100.3 98.7 102.6 96.2 101.7 92.2 92.6 75.7 82.8 59.8 69.6 5IN-37740 0.0 0.0 0.0 0.0 0.0 0.0 2.0 0.9 7.4 5.7 9.8 10.4 1IN-R5Q093 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.7 1.4 3IN-V9367 0.0 n.a. 0.0 n.a. 0.0 n.a. 2.0 n.a. 3.0 n.a. 3.1 n.a. 3Total other unknowns4 4.5 1.3 5.8 0.0 5.8 0.1 7.1 6.1 8.6 3.6 6.2 4.7 5Uncharacterized extracted residues5 0.6 0.7 Extracted residues 0.6 0.7 5.1 3.8 5.1 2.6 4.2 4.7 7.7 6.8 7.4 8.1 9Unextracted residues 0.1 0.2 0.8 0.6 0.9 0.4 2.6 1.9 6.4 5.5 21.0 14.3 2

Fulvic acids 

n.p. 

Humic acids Humin 

CO26 n.p. n.p. 0.4 0.1 0.4 0.1 0.4 0.1 0.4 0.1 0.5 0.1 0Other volatile compounds ORBO tubes were not analyzed. Mass balance 100.6 102.6 105.6 103.3 103.5 102.3 104.3 104.3 102.6 103.4 102.8 102.2 10

Data obtained from Table 7, p. 48; Table 10A, p. 53; Table 11A, p. 55; Table 12B, p. 57 of the study report. n.a. = Not applicable. n.p. = Not performed. 1 Sampling site not described (pond, lake, river, ditch, rice paddy, etc.). 2 PY = pyridine label, MD = pyrimidine label. 3 Tentative identification based on LC/MS/MS molecular weight and fragmentation pattern (p. 36). 4 Comprised of up to seventeen components, with no individual component >5% of applied in total system (Table 10A, p. 53; Table 11A, p. 

81-88). 

5 Sediment extracts not analyzed by HPLC. 6 Per label, all samples were connected to the same set of volatile traps. 
E. Transformation of Parent Compound: Transformation kinetics of the parent compound are 

summarized in Figures 1a and 1b and Table 9, with transformation product information 

summarized in Table 10. Rates of transformation of parent nicosulfuron and transformation product 

profiles were similar between the sand and silt loam sediments. 

Using simple first order (SFO) regression analysis (ModelMaker 4.0), the study author calculated 

nicosulfuron half-life and DT90 values of 98.0 and 325.5 days, respectively, in the sand sediment 

(Tift) system and 90.2 and 299.7 days, respectively, in the silt loam sediment (Boonville) system 

(pp. 30-31, 36-37; Figure 13B, p. 100; Figure 14, p. 102). Transformation kinetics of nicosulfuron 

in the systems were also evaluated using first order multi compartment (FOMC), hockey stick (HS) 

and double first order in parallel (DFOP) models in accordance with FOCUS kinetics guidance 

(2006; Appendix 2, pp. 108-128). 

Figure 1a. Transformation Kinetics of Nicosulfuron (Combined Labels) in Total Natural 

Water:Sand Sediment1, 2, 3 

Nicosulfuron in Total Sand Sediment System

Days Nicosulfuron

0

0

 3

 3

 7

 7

 14

 14

 31

 31

 60

 60

 80

 80

 102

 102

97.1

95.2

101.

100.

96.9

99.3

89.7

98.0

80.5

91.6

62.5

66.0

55.8

62.6

45.5

53.9

0 20 40 60 80 100

0

20

40

60

80

100

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 101 336 2.7 101 k  0.00685

DFOP 106 326 1.8 96.2 f  -0.0858k0  0.52k1  0.00732

IORE 98.5 217 2.7 101 N  0.404k  0.09

SC

SSFO

Slowt1 2

tRIORE

 322

 287

94.6

65.4

1 Sampling site (located in Georgia) was not described (pond, lake, river, ditch, rice paddy, etc.). 

2 Data were obtained from Table 8A, p. 49; Table 9A, p. 51 of the study report, with kinetics calculated by reviewer 

using R 8.5 (DER Attachment 2). 

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

Equation (IORE).
Nicosulfuron (PC 129008) MRID 48790905 

Page 15 of 28 

Figure 1b. Transformation Kinetics of Nicosulfuron (Combined Labels) in Total Natural 

Water:Silt Loam Sediment System1, 2, 3 

Nicosulfuron in Total Silt Loam Sediment System

Days Nicosulfuron

0

0

 3

 3

 7

 7

 14

 14

 31

 31

 60

 60

 80

 80

 102

 102

95.5

100.

98.7

 103.

96.2

 102.

92.2

92.6

75.7

82.8

59.8

69.6

52.6

57.7

45.6

49.7

0 20 40 60 80 100

0

20

40

60

80

100

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 92.3 307 1.8 102 k  0.00751

DFOP 92.3 307 2 102 f  0.188k0  0.0075k1  0.00751

IORE 92.2 294 1.9 101 N  0.948k  0.0094

SC

SSFO

Slowt1 2

tRIORE

 213

 179

92.4

88.5

1 Sampling site (located in Missouri) was not described (pond, lake, river, ditch, rice paddy, etc.). 

2 Data were obtained from Table 10A, p. 53; Table 11A, p. 55 of the study report, with kinetics calculated by reviewer 

using R 8.4; R 8.5 would not plot data (DER Attachment 2). 

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

Equation (IORE). 
Nicosulfuron (PC 129008) MRID 48790905 

Page 16 of 28 

Table 9. Transformation Kinetics of Nicosulfuron in Total Aquatic Systems1, 2 

System3 

Observed 

DT50 

(days)4 

Observed 

DT90 

(days)4 

Calculated

Half-life

(days) 

Kinetics 

Model5 Model Parameters Model Statistics

Georgia natural 

water:sand sediment 

system (20°C, water 

pH 7.6, sediment pH 

7.6)

ca. 101 >102 

101 SFO C0 = 101, k = 0.00685 

Sc = 322, 

SSFO = 287, 

r

2 = --

98.5 IORE C0 = 101, k = 0.09, 

N = 0.404

tR IORE = 65.4, 

r

2 = -- 

106 DFOP 

[if applicable]

C0 = 96.2, k0 = 0.52, 

k1 = 0.00732, 

f = -0.0858

Slow t1/2 = 94.6, 

r

2 = -- 

Missouri natural 

water:silt loam 

sediment system 

(20°C, water pH 7.9, 

sediment pH 7.8)

ca. 95 >102 

92.3 SFO C0 = 102, k = 0.00751 

Sc = 213, 

SSFO = 179, 

r

2 = -- 

92.2 IORE C0 = 101, k = 0.0094, 

N = 0.948 

tR IORE = 88.5, 

r

2 = -- 

92.3 DFOP 

[if applicable]

C0 = 102, k0 = 0.0075, 

k1 = 0.00751, f = 0.188

Slow t1/2 = 92.4, 

r

2 = -- 

1 Calculated by the reviewer using R v. xxDeg_0.8.5 (sand sediment) and R v. xxDeg_0.8.4 (silt loam sediment) and 

data obtained from Table 8A, p. 49; Table 9A, p. 51; Table 10A, p. 53; Table 11A, p. 55 of the study report (DER 

Attachment 2); -- = not calculated by R. 

2 Calculated half-lives and model parameters for the best fit kinetics models, in accordance with the NAFTA kinetics 

guidance (USEPA, 2011), are in bold. 

3 Sampling site not described (pond, lake, river, ditch, rice paddy, etc.). 

4 Based on mean nicosulfuron levels at each interval.

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

Equation (IORE). 

One major transformation product and two minor products were detected in both systems (pp. 35-

36; Figure 1, pp. 58-59): 

 2-[[(3,4-dihydro-6-methoxy-4-oxopyrimidin-2-yl]aminocarbonyl]aminosulfonyl]-N,Ndimethyl-3-pyridinecarboxamide (IN-37740), 

 2-[[[[(1,6-dihydro-4-hydroxy-6-oxo-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-N,Ndiemethyl-3-pyridinecarboxamide (IN-R5Q09), and 

 2-(aminosulfonyl)-N,N-dimethyl-3-pyridinecarboxamide (IN-V9367). 

Identification of major product IN-37740 was confirmed against reference standard using 

LC/MS/MS (p. 36; Figures 12D-12F, pp. 92-94). Tentative identification of minor product INR5Q09 was based on LC/MS/MS molecular weight and fragmentation pattern (p. 36; Figures 12G12J, pp. 95-98). 

 
Nicosulfuron (PC 129008) MRID 48790905 

Page 17 of 28 

Table 10. Transformation Products of Nicosulfuron (Combined Labels) in Total Aquatic 

Systems

System1 Transformation 

product(s)2 

Maximum 

%AR 

Observed 

Associated 

Interval 

(days) 

Final %AR 

Observed 

Final Interval 

(days) 

Georgia natural 

water:sand sediment 

system (20°C, water pH 

7.6, sediment pH 7.6)

IN-37740 13.9 80 13.1 102 

IN-R5Q09 6.6 102 6.6 102 

IN-V9367 4.8 102 4.8 102 

Missouri natural water:silt 

loam sediment system 

(20°C, water pH 7.9, 

sediment pH 7.8)

IN-37740 13.0 80 11.6 102 

IN-R5Q09 5.8 102 5.8 102 

IN-V9367 4.2 102 4.2 102 

Data obtained from Table 8A, p. 49; Table 9A, p. 51; Table 10A, p. 53; Table 11A, p. 55 of the study report. 

1 Sampling site not described (pond, lake, river, ditch, rice paddy, etc.). 

2 IN-37740 and IN-R5Q09 contained both pyridine and pyrimidine labels; IN-V9367 contained pyridine label. 

 

A transformation pathway was provided by the study author and is illustrated below (p. 37; Figure 

15, p. 103). Nicosulfuron yields IN-37740 through demethylation of a pyrimidinyl methoxy group, 

with O-demethylation then yielding IN-R5Q09 (tentative identification). Hydrolysis of the sulfonyl 

urea bridge of IN-37740 or IN-R5Q09 yields IN-V9367. 

Figure 2. Anaerobic Aquatic Degradation Pathway of Nicosulfuron (DPX-V9360) 
Nicosulfuron (PC 129008) MRID 48790905 

Page 18 of 28 

III. Study Deficiencies and Reviewer's Comments 

1. The study was conducted for an insufficient length of time. The study duration should normally 

not exceed 100 days, but should be conducted until the decline of the test compound and the 

formation and decline of transformation products are established, or for no more than one year. 

For both systems, half-lives for nicosulfuron occurred near the final sampling interval, the major 

product IN-37740 had only decreased from maximums of 13.0-13.9% of the applied at 80 days 

to 11.1-13.1% at study termination, and maximum levels of the products IN-R5Q09 (5.8-6.6%) 

and IN-V9367 (4.2-4.8%) occurred at study termination. 

2. Unextracted [14C]residues were detected at 10.4-20.2% and 14.3-28.9% of the applied in the 

sand and silt loam sediments, respectively, at 60-102 days, but only the 102-day samples were 

characterized through organic matter fractionation. 

3. The study author failed to demonstrate that parent nicosulfuron was stable in water layer and 

sediment extract samples prior to analysis. Water layer and sediment extracts were reported as 

"typically" analyzed within 24 hours and 1 week, respectively, from sampling (p. 24). The 

study author reported that water layer and sediment extracts were "stored in a freezer (ca. 

20oC)", which appears to be in error (p. 24). In the Materials and Methods section 3.5.4 Sample 

Storage Conditions (p. 24), the study author reported water layer samples were re-analyzed after 

70 days of storage, then in the Results and Discussion section 4.8 Storage Stability (p. 37) 

reported re-analysis of sediment extracts conducted up to 70 days after initial HPLC analysis 

found "the profiles remaining approximately the same"; additional details and supporting 

quantitative results and chromatograms were not provided. Given that the majority of the 

residues resided in the water column, the reported re-analysis of sediment extracts after storage 

most likely refers to re-analysis of water layer samples. 

Re-analysis of the pyridine-2- and pyrimidine-2-label dosing solutions after 119 days of storage 

found radiochemical purities of 95.5% and 98.5%, respectively (p. 37). 

4. The study author failed to specify that the nominal test application rate used in this study was 

equivalent to the maximum field use rate, which impacts maximum concentrations of 

nicosulfuron transformation products that may be detected. 

If the test application rate significantly exceeds the maximum field use rate, it must be shown 

that an exaggerated application rate does not adversely affect the microbial activity of the 

water:sediment system, and thereby influence the rate and route of transformation of the test 

compound and the formation and decline of transformation products. OCSPP guidelines specify 

that data from exaggerated dose studies should only be used for degradate identification 

purposes. 

5. All samples from a given treatment (sediment type, label) were connected in series to the same 

set of volatile traps (p. 21; Figure 2, p. 61). The reported concentration of CO2 was adjusted 

based on the number of samples in the series at the time of sampling (p. 30). It is preferred that 

sample vessels be connected to individual volatile traps so that more precise material balances 

for each sample can be calculated. 
Nicosulfuron (PC 129008) MRID 48790905 

Page 19 of 28 

6. Collection and storage of the sediments and associated waters were not adequately described. 

a) The pesticide use histories for the source sites for the test sediments and associated 

waters were not reported. The sediment and water were not analyzed for pesticides to 

establish that they were not contaminated prior to treatment. 

b) The sampling sites were not described (pond, lake, river, ditch, rice paddy, etc.). 

c) Collection procedures (sampling methods, depths) were not described. 

d) Sediments and associated waters appear to have been stored separately; sediments 

reported as stored at ca. 4oC in darkness, but storage of waters was not reported. The 

length of storage prior to preparation of water:sediment systems for pretreatment 

acclimation was reported as less than one month, but collection dates were not reported. 

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. 

7. For the Boonville test systems, the water:sediment volume ratio used, taking into account water 

associated with the sediment, was 5.5:1 (422 g total water:76.1 g dry wt. sediment). Current 

OCSPP guidelines recommend a minimum amount of 50 g of sediment (dry wt. basis) per 

incubation vessel is utilized, a sediment layer of 2.5 ± 0.5 cm, and a water:sediment volume 

ratio between 3:1 and 4:1. 

8. In section 3.7.1.1 Material Balance of the study report (pp. 29-30), ethylene glycol traps are 

mentioned, and in Figure 2 (p. 61) the schematic of the flow-through apparatus indicates a liquid 

organic volatiles trap ("5") was used. ORBO-32 tubes were used in lieu of ethylene glycol (pp. 

21-22). 

9. Page 43 of the study report was missing; page 42 was duplicated. 

10. In Tables 8A-11B (pp. 49-56), both the Tift and Boonville systems are described as "(Loam)", 

when the systems are characterized as sand and silt loam sediments, respectively (Table 1, p. 

40). 

 

IV. References 

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

Guidelines, OPPTS 835.4400, Anaerobic Aquatic Metabolism. Office of Prevention, Pesticides 

and Toxic Substances, Washington, DC. EPA 712-C-08-019. 

2. U.S. Environmental Protection Agency. 2011. Guidance for Evaluating and Calculating 

Degradation Kinetics in Environmental Media. (Interim draft document dated Dec. 21, 2011.) 
Nicosulfuron (PC 129008) MRID 48790905 

Page 20 of 28 

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

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Ma

%A

PARENT

Nicosulfuron  (DPX-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: 410.411 g/molSMILES: c1(c(nccc1)S(=O)(=O)NC(=O)Nc2nc(cc(n2)OC)OC)C(=O)N(C)C

S

O

O

O

O CH3O CH3

NN

NH

NH O

N

H3C

H3C

N

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905

Natu

sand 

101

Natu

s

se

102

MAJOR (>10%) TRANSFORMATION PRODUCTS 

IN-37740 CAS: 2-[[(3,4-Dihydro-6-methoxy4-oxopyrimidin-2-

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

H16

N6O6S 

MW: 396.38 g/molSMILES: c1(c(nccc1)S(=O)(=O)NC(N/C2=N/C(=C\C(N2)=O)OC)=O)C(N(C)C)=O

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905

Natu

sand 

13.9

Natu

s

se

13.0

Unextracted 

residues NA NA 

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905

Natu

sand 

20.2
Nicosulfuron (PC 129008) MRID 48790905 

Page 21 of 28 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Ma

%A

Natu

s

se

28.9

MINOR (<10%) TRANSFORMATION PRODUCTS

IN-R5Q09 CAS: 2-[[[[(l,6-Dihydro-4-hydroxy6-oxo2-pyrimidinyl)amino]carbonyl] 

amino]sulfonyl]-N-N-dimethyl-3 - pyridinecarboxamide) Formula: C13

H14

N6O6S 

MW: 382 g/molSMILES: CN(C)C(=O)c1cccnc1S(=O)(=O)NC(=O)NC2=NC(=O)CC(=N2)O

NH

N

OO

N

NH

O

NH

S

O

O

N

H3CH3C

O

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905

Natu

sand 

6.6% 

Natu

s

se

5.8% 

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

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

N3O3S 

MW: 229.259 g/molSMILES: c1(cccnc1S(=O)(=O)N)C(=O)N(C)C 

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905

Natu

sand 

4.8% 

Natu

s

se

4.2% 

Carbon dioxide IUPAC: Carbon dioxide 

Formula: CO2

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

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905

Natu

sand 

4.6

Natu

s

se

0.5% 
Nicosulfuron (PC 129008) MRID 48790905 

Page 22 of 28 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Ma

%A

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: c12cccnc1S(NC2=O)(=O)=O 

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905 

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

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

MW: 155.15 g/molSMILES: Nc1nc(cc(n1)OC)OC 

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905 

IN-GDC42 CAS: 2-

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

H13

N5O5S 

MW: 315.309 g/molSMILES: c1(ncccc1C(=O)N(C)C)S(NC(NC(N)=O)=O)(=O)=O

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905 
Nicosulfuron (PC 129008) MRID 48790905 

Page 23 of 28 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRID Ma

%A

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

methoxy-6-(methyldioxy)-2-pyrimidinyl]amino]-N,N-dimethyl3-pyridinecarboxamide

Formula: C15

H18

N6O4

MW: 346.34 g/molSMILES: NC(N(c1nc(cc(n1)OC)OC)c2ncccc2C(N(C)C)=O)=O

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905 

IN-HYY21 CAS: 2-

[[[[(Aminoiminomethyl)amino]carbonyl]amino]sulfonyl]-N,Ndimethyl-3-pyridinecarboxamideFormula: C10

H14

N6O4S 

MW: 314.33 g/molSMILES: c1(c(nccc1)S(=O)(=O)NC(NC(=N)N)=O)C(N(C)C)=O

835.4400 

Anaerobic 

aquatic 

metabolism 

48790905 

A AR means “applied radioactivity”. MW means “molecular weight”. NA means "not applicable". 1 IN-37740 and IN-R5Q09 contained both pyridine and pyrimidine labels; IN-V9367 contained pyridine label.
Nicosulfuron (PC 129008) MRID 48790905 

Page 24 of 28 

Attachment 2: Statistics Spreadsheets and Graphs 

Chemical: Nicosulfuron MRID: 48790905 PC: 129008 Guideline: 835.4400 pE + pH: Georgia Sand Sediment (Tift) System - Treated Days Water layer Sediment Posttreatment 

Measured 

Eh Measured pH pE pE + pH 

pE + pH < 

12? 

Measured 

Eh Measured pH pE pE + p

0 -189.8 7.905 -3.2 4.7 Yes -223.4 7.195 -3.8 3.4 0 -176.3 7.790 -3.0 4.8 Yes -220.3 7.140 -3.7 3.4 3 -139.1 8.607 -2.3 6.3 Yes -133.2 7.195 -2.3 4.9 3 -62.5 7.784 -1.1 6.7 Yes -204.7 7.099 -3.5 3.6 7 -127.8 7.582 -2.2 5.4 Yes -207.2 7.087 -3.5 3.6 7 -88.3 7.430 -1.5 5.9 Yes -211.8 7.088 -3.6 3.5 

14 -130.1 7.484 -2.2 5.3 Yes -219.9 7.088 -3.7 3.4 14 -72.0 7.422 -1.2 6.2 Yes -203.8 7.084 -3.4 3.6 31 -153.0 7.704 -2.6 5.1 Yes -219.4 7.119 -3.7 3.4 31 -36.2 7.596 -0.6 7.0 Yes -193.3 7.130 -3.3 3.9 60 -225.1 8.264 -3.8 4.5 Yes -272.2 7.334 -4.6 2.7 60 -215.3 8.330 -3.6 4.7 Yes -253.0 7.314 -4.3 3.0 80 -147.5 8.262 -2.5 5.8 Yes -224.6 7.311 -3.8 3.5 80 -200.7 8.494 -3.4 5.1 Yes -238.4 7.356 -4.0 3.3 

102 -219.1 8.478 -3.7 4.8 Yes -231.6 7.465 -3.9 3.6 102 -122.7 8.664 -2.1 6.6 Yes -196.1 7.534 -3.3 4.2 

Data from Table 4A, p. 45 of the study report. Days Posttreatment, Measured Eh and Measured pH are input fields. pE, pE + pH and pE + pH < 12? are output fields. 
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Chemical: Nicosulfuron MRID: 48790905 PC: 129008 Guideline: 835.4400 pE + pH: Missouri Silt Loam Sediment (Boonville) System - Treated Days Water layer Sediment Posttreatment 

Measured 

Eh Measured pH pE pE + pH 

pE + pH < 

12? 

Measured 

Eh Measured pH pE pE + p

0 -161.0 7.415 -2.7 4.7 Yes -246.9 7.229 -4.2 3.1 0 -160.9 7.680 -2.7 5.0 Yes -236.3 7.230 -4.0 3.2 3 -204.1 7.630 -3.4 4.2 Yes -233.8 7.221 -3.9 3.3 3 -165.1 7.631 -2.8 4.8 Yes -205.8 7.341 -3.5 3.9 7 -156.0 7.480 -2.6 4.8 Yes -230.9 7.229 -3.9 3.3 7 -146.6 7.477 -2.5 5.0 Yes -236.1 7.222 -4.0 3.2 

14 -154.3 7.294 -2.6 4.7 Yes -239.7 7.194 -4.0 3.1 14 -148.4 7.554 -2.5 5.0 Yes -242.8 7.191 -4.1 3.1 31 -199.4 7.348 -3.4 4.0 Yes -236.6 7.134 -4.0 3.1 31 -227.9 7.427 -3.8 3.6 Yes -238.5 7.187 -4.0 3.2 60 -195.5 7.757 -3.3 4.5 Yes -243.4 7.203 -4.1 3.1 60 -210.2 8.106 -3.6 4.6 Yes -254.1 7.225 -4.3 2.9 80 -212.5 7.957 -3.6 4.4 Yes -221.5 7.248 -3.7 3.5 80 -165.6 8.061 -2.8 5.3 Yes -189.9 7.212 -3.2 4.0 

102 -240.6 8.153 -4.1 4.1 Yes -239.0 7.336 -4.0 3.3 102 -245.6 8.248 -4.1 4.1 Yes -249.5 7.332 -4.2 3.1 

Data from Table 5A, p. 46 of the study report. Days Posttreatment, Measured Eh and Measured pH are input fields. pE, pE + pH and pE + pH < 12? are output fields. 
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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) 

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 foequation 9). Half-lives for the IORE model are calculated using equation 5, which represents a first-order half-life tha

DT90 of the IORE model. (Traditional DT50 and DT90 values for the IORE model can be calculated using equations 6 
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 (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) 

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, 

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 (-) 
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Cmodel,t = modelled 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 S

C, the SFO model is adequate to describe kinetics. If not, the faster of tIORE or the DFOP DT50 for 

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