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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, DC 20460

OFFICE OF PREVENTION,

PESTICIDES AND TOXIC SUBSTANCES

MEMORANDUM

DATE: 19 January 2010

SUBJECT: Thifensulfuron Methyl. Petition to Establish a Permanent Tolerance 

(Associated with Regional Section 3 Registration) for Residues Resulting 

from Food/Feed Use of the Herbicide on Safflower. Summary of Analytical 

Chemistry and Residue Data.

PC Code: 128845 DP Barcode: D361945

Decision Number: 405073 Registration Number: 352-633

Petition Number: 9F7523 Regulatory Action: Amended Section 3

Risk Assessment Type: NA Case Number: NA

TXR Number: NA CAS Number: 79277-27-3

MRID Number: 47641801 40CFR: §180.439

Chemical Class: Triazinylsulfonylurea Herbicide Trade Name: DuPontTM Harmony® SG

FROM: William T. Drew, Chemist

Risk Assessment Branch 2 (RAB2)

Health Effects Division (HED), 7509P

THRU: Dennis McNeilly, Chemist

RAB2/HED, 7509P

TO: Barbara Madden, RM Team 5

Risk Integration, Minor Use and Emergency Response Branch (RIMUERB)

Registration Division (RD), 7505P

This residue chemistry summary document was originally prepared under contract by Dynamac Corporation (1901 

Research Boulevard, Suite 220; Rockville, MD 20850). It has been reviewed by the Health Effects Division (HED),

and revised to reflect current Office of Pesticide Programs (OPP) policies.
Thifensulfuron Methyl Summary of Analytical Chemistry and Residue Data DP Barcode D361945

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Executive Summary

Thifensulfuron methyl is a sulfonylurea herbicide (Group 2) registered to E.I. DuPont de 

Nemours for the control of broadleaf weeds on cereal grains (barley, field corn, oat, rice, 

sorghum, triticale and wheat), canola, cotton, flax and soybeans. The current registered use 

patterns on these crops include post-emergence, and pre-plant or at-planting burndown. 

Thifensulfuron methyl is absorbed through the foliage of treated weeds, inhibiting growth,

causing necrosis of the growing plant, and eventual plant death. 

The Interregional Research Project Number 4 (IR-4), has submitted a tolerance petition, 

9F7523, proposing the establishment of a tolerance for “combined” residues of the herbicide 

thifensulfuron methyl (with the CAS name of methyl-3-[[[[(4-methoxy-6-methyl-1, 3, 5-triazin2-yl)amino] carbonyl] amino] sulfonyl]-2-thiophenecarboxylate) in or on safflower seeds, the 

raw agricultural commodity (RAC), as listed below. 

Safflower, seed.....................................................................0.05 ppm

The end-use product (EP) proposed for use on safflower is DuPontTM Harmony® SG 

Herbicide (EPA Registration #352-633), a soluble granule (SG) formulation containing 50% (by

weight) thifensulfuron methyl as the active ingredient (ai). Harmony® SG is proposed for one 

post-emergence broadcast foliar spray on safflower at a maximum application rate of 0.019 

pound ai per acre (lb ai/A), with a pre-harvest interval (PHI) of 81 days. Application may be 

made up to the time of flower bud initiation, using ground or aerial equipment, with adjuvants in 

the spray mixture. The proposed use is limited to safflower grown in the states of North Dakota, 

South Dakota, Nebraska, Montana (East of Route 87 or East of I-15), and Wyoming (East of I-25 

or North of I-90). 

Tolerances for residues of thifensulfuron methyl are listed under 40CFR §180.439[a]. 

Permanent tolerances are established for thifensulfuron methyl in/on barley, canola, corn, cotton, 

flax, oat, rice, sorghum, soybean, and wheat commodities, at levels ranging from 0.02 to 2.5

ppm. No tolerances are currently established for residues in animal commodities or rotational 

crops. 

The nature of the residue in plants is adequately understood, based on acceptable studies 

with wheat, corn and soybeans. The metabolism of thifensulfuron methyl in tested crops 

proceeds by hydrolysis of the methyl ester and sulfonyl urea moieties, with some demethylation 

of the triazine methoxy group. HED has previously determined that the residue of concern 

(ROC) in plant commodities is thifensulfuron methyl for the purposes of tolerance enforcement,

and risk assessment. The available plant metabolism studies are adequate to support the 

requested use on safflower. 

The nature of the residue in livestock is adequately understood, based on the available 

goat metabolism study. This determination is based on the low level of transfer of thifensulfuron 

methyl residues to goat matrices, and the lack of detectable residues in livestock feed items, even 

at exaggerated application rates. HED concluded that, because no detectable residues of 

thifensulfuron methyl were found in registered poultry feed items, a poultry metabolism study is 

not required. HED has previously determined that the ROC in plant commodities is 
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thifensulfuron methyl for the purposes of tolerance expression, and risk assessment. The current 

safflower petition does not alter HED’s earlier conclusions regarding livestock metabolism. 

Two high performance liquid chromatography (HPLC) photo-conductivity detection 

methods (Methods AMR-646-86 and AMR-761-87) are available for enforcing tolerances for 

residues of thifensulfuron methyl in cereal grains and straw. A liquid chromatography with mass 

spectrometric detection (LC/MS) method (DuPont Method 1381) is also available for enforcing 

tolerances for residues of thifensulfuron methyl in canola, cotton and flax commodities; the 

validated limit of quantitation (LOQ) for this method is 0.020 ppm. The LC/MS method will be 

suitable for enforcing the proposed tolerance in safflower seed. The FDA multiresidue methods 

are not suitable for tolerance enforcement, as thifensulfuron methyl is not recovered through any

of the FDA Multiresidue Method Testing protocols. Samples collected from the safflower field

trial and processing studies were analyzed for residues of thifensulfuron methyl using an HPLC 

photo-conductivity method (DuPont Method AMR-973-87). The method was adequate for data 

collection based on acceptable method validation and concurrent method recoveries. 

The available storage stability data adequately support the sample storage durations and 

conditions incurred during the safflower field trial and processing studies. No storage stability

corrections need to be applied to the safflower field trial and processing study results. 

According to OPPTS Residue Chemistry Test Guideline 860.1000, Table 1 Feedstuffs 

(June 2008), safflower meal is the only animal feedstuff associated with the current petition. 

Safflower meal may constitute up to 5% of beef cattle diet, 10% of dairy cattle diet, 25% of 

poultry diet, and 5% of swine diet. In consideration of the proposed regional use of 

thifensulfuron methyl on safflower, and the observed residues of <0.050 ppm in safflower meal, 

the potential contribution to the maximum reasonably balanced dietary burdens of livestock is 

negligible. Therefore, tolerances in meat, milk, poultry and eggs are not required for this 

petition. 

The submitted residue data for safflower seeds are adequate to fulfill data requirements 

for the requested use in the states of North Dakota, South Dakota, Nebraska, Montana (East of 

Route 87 or East of I-15), and Wyoming (East of I-25 or North of I-90). The number and 

location of the safflower field trials support the requested regional use of Harmony® SG on 

safflower. The data reflect the proposed use pattern, which involves a maximum use rate of 

0.019 lb ai/A, a minimum PHI of 81 days, and use of a non-ionic surfactant (NIS) in the spray

mixture. HED concludes that the proposed tolerance of 0.05 ppm is appropriate. 

The submitted safflower processing study showed that residues of thifensulfuron methyl 

were <0.050 ppm in safflower meal, and refined oil, processed from safflower seeds treated at a 

1X rate. DuPont has previously submitted a processing study depicting the magnitude of 

thifensulfuron methyl residue in cotton seeds. Residues of thifensulfuron methyl were nondetectable (<0.006 ppm) in cotton seeds harvested at normal maturity (133 days after treatment) 

following a single defoliant broadcast application of the 50% ai dry flowable (DF) formulation at 

0.094 lb ai/A (roughly 4X the normal use rate), made one day after planting of cotton. The 

requirement for processing studies in canola and flax has previously been waived, based on the 

results of the cotton study. Therefore, a 5X safflower processing study is not required, because 

residues are not expected to be found in the processed commodities. 
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An analytical standard for thifensulfuron methyl is currently available in the National 

Pesticide Standards Repository (NPSR). 

Confined rotational crop studies have previously been submitted. These studies were 

initially reviewed by the Environmental Fate and Effects Division (EFED), and were deemed 

inadequate pending submission of additional data and information to upgrade the acceptability of 

a greenhouse confined rotational crop study with [triazine-2-

14C]-thifensulfuron methyl. The 

requested data and information have been submitted, and reviewed by HED. HED concluded 

that although the data are not fully adequate, a new confined rotational crop study will not be 

required because of the nature of the pesticide. It is unlikely that additional ROCs would be 

found if the study were repeated. No field rotational crop studies have been submitted for 

thifensulfuron methyl, and none are required for this petition. The 45-day plantback interval 

(PBI) on the product label for Harmony® SG is adequate. 

Regulatory Recommendations and Residue Chemistry Deficiencies

Pending submission of a revised Section F, there are no major deficiencies which would 

preclude the establishment of a permanent tolerance for regional use of thifensulfuron methyl (as 

Harmony® SG) on safflower. Provided that the forthcoming human health risk assessment 

(D361902; W.T. Drew; 29 January 2010) does not identify any issues of concern, the submitted 

data support a regional tolerance for residues of thifensulfuron methyl, including its metabolites 

and degradates, in or on safflower seeds, at the level listed below. Compliance with the tolerance 

level specified below is to be determined by measuring thifensulfuron methyl only. 

Safflower, seed.....................................................................0.05 ppm

The deficiency noted in this document is presented below. 

860.1550 Proposed Tolerances

A revised Section F should be submitted to delete the word “combined” from the 

tolerance expression. 

Note to RD: According to HED’s Interim Guidance on Tolerance Expressions (S. 

Knizner, 27 May 2009), the tolerance expression for thifensulfuron methyl cited in 40CFR 

§180.439[a] should be revised to state: 

Tolerances are established for residues of thifensulfuron methyl, including its 

metabolites and degradates, in or on the commodities listed in the table 

below. Compliance with the tolerance levels specified below is to be 

determined by measuring only thifensulfuron methyl (methyl 3-[[[[(4-

methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino] sulfonyl]-2-

thiophenecarboxylate). 
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Background

The chemical structure and nomenclature of thifensulfuron methyl are presented in Table 

1, below. The physicochemical properties of the technical grade of thifensulfuron methyl are 

presented in Table 2, below.

TABLE 1 Thifensulfuron Methyl Nomenclature. 

Chemical structure

N

N

N

CH3

O

CH3

N

H

N

H

O

S

CO2CH3

S

O

O

Common name Thifensulfuron methyl

Molecular formula C12H13N5O6S2

Molecular weight 387.38

Company experimental 

name

DPX-M6316

IUPAC name Methyl 3-(4-methoxy-6-methyl-1,3,5-triazin-2-ylcarbamoylsulfamoyl) thiophene-2-

carboxylate

CAS name Methyl 3-[[[[(4-methoxy-6-methyl-1,3,5- triazin-2-yl)amino]carbonyl]amino] 

sulfonyl]-2-thiophenecarboxylate

CAS registry number 79277-27-3

End-use product (EP) Field trials: 75% ai DF, DuPontTM Harmony® GT XP, EPA Registration #352-446

Proposed use: 50% ai SG, DuPontTM Harmony® SG, EPA Registration #352-633

TABLE 2 Physicochemical Properties of Thifensulfuron Methyl. 

Parameter Value Reference

Melting point/range (oC) 171.1 ± 1.2 MRID #47138301 (D342084;

pH 4.0 D. Dotson; 17 April 2008)

Density (g/cm3) 1.58 ± 0.004 

Water solubility (g/L at 25oC) pH 5 0.223

pH 7 2.24

pH 9 8.83

Solvent solubility (g/L at 25oC) Acetone - 11.9

Acetonitrile - 7.3

Dichloromethane - 27.5

Ethanol - 0.9

Ethyl acetate - 2.6

Hexane - <0.1 

Methanol - 2.6 

Xylene - 0.2
Thifensulfuron Methyl Summary of Analytical Chemistry and Residue Data DP Barcode D361945

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TABLE 2 Physicochemical Properties of Thifensulfuron Methyl. 

Parameter Value Reference

Vapor pressure (25oC) 1.7 x 10-8Pa (1.3 x 10-10 mm Hg)

Dissociation constant (pKa) 4.0

Octanol/water partition coefficient

(Log [KOW])

pH 5 1.06 

pH 7 0.0222

pH 9 0.0078 

UV/visible absorption (max, λ) pH <2 224, 250 nm

pH 7 233 nm

pH >10 234 nm

860.1200 Directions for Use

The EP proposed for use on safflower is DuPontTM Harmony® SG herbicide (EPA 

Registration #352-633), an SG formulation containing 50% thifensulfuron methyl as the ai. The 

proposed use directions for safflower are summarized in Table 3 (below), and were extracted 

from an undated supplemental label. The proposed use directions are consistent with the 

information provided in a revised Section B. 

TABLE 3 Summary of Proposed Use of Thifensulfuron Methyl on Safflower. 

Application 

Timing; Type;

and Equipment

EP

[EPA 

Registration #]

Use Rate

(lb ai/A)

Max. # of 

Uses per 

Season

Max. 

Seasonal 

Use Rate

(lb ai/A)

PHI

(Days)

Use Directions and 

Limitations 2

Post-emergence (up 

until flower bud 

initiation);

broadcast foliar;

ground or aerial 1

Harmony® SG, 

50% ai

[352-633]

0.014-

0.019

1 0.019 81 Use limited to North 

Dakota, South Dakota, 

Nebraska, Montana (east 

of Route 87 or east of I15), and Wyoming (east of 

I-25 or north of I-90). 

Spray adjuvants may be 

included with the spray 

treatment.

3

1. The supplemental label does not specify application spray volumes. The approved label specifies minimum spray 

volumes of 10-25 gallons per acre (GPA) via ground equipment, and 5 GPA via aerial equipment for most 

field crops. The field trials were conducted in 15-19 GPA via ground equipment. 

2. The approved label specifies the following rotational crop restrictions: Wheat, barley, oat, triticale, soybeans, and 

field corn may be replanted anytime after the application of Harmony® SG. Any other crop may be planted 

45 days after the application of Harmony® SG. 

3. Non-ionic surfactants (NISs) may be mixed with the spray mixture at a rate of 2-4 pints per 100 gallons of spray 

solution (concentration of 0.25-0.55% v/v). The surfactant product must contain at least 60% NIS, with a 

hydrophilic/lipophilic balance (HLB) greater than 12. Crop oil concentrate may be used under dry 

conditions or during cool weather. A petroleum-based oil concentrate may be used in place of an NIS at 1-

2% (v/v). Use an oil adjuvant that contains at least 80% of a high quality, petroleum (mineral) or modified 

vegetable seed oil with at least 15% surfactant emulsifiers. 
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Conclusions: The proposed label directions for Harmony® SG are adequate to allow 

evaluation of the residue data. Although the submitted magnitude of the residue study for 

safflower reflects the use of a 75% ai dry flowable (DF) formulation (as opposed to the requested 

50% ai SG formulation), the field trials reflect the proposed use rate, and PHI. 

860.1300 Nature of the Residue - Plants

Residue Chemistry Memo D342084; D. Dotson; 17 April 2008 (PP#7F7219)

Residue Chemistry Memo D301509; J. Facey; 10 June 2004 (Metabolism Decision Document)

The nature of the residue in plants is adequately understood, based on acceptable studies 

with wheat, corn and soybeans. The salient features of these metabolism studies were recently

summarized in a residue chemistry summary document (D342084; D. Dotson; 17 April 2008). 

The metabolism of thifensulfuron methyl in tested crops proceeds by hydrolysis of the methyl 

ester and sulfonyl urea moieties, with some demethylation of the triazine methoxy group. HED 

has determined that the ROC in plant commodities is thifensulfuron methyl for the purposes of 

tolerance expression, and risk assessment. The available plant metabolism studies are adequate 

to support the requested use on safflower. 

860.1300 Nature of the Residue - Livestock

Residue Chemistry Memo D342084; D. Dotson; 17 April 2008 (PP#7F7219)

Residue Chemistry Memo D301509; J. Facey; 10 June 2004 (Metabolism Decision Document)

The nature of the residue in livestock is adequately understood, based on the available 

goat metabolism study. HED has previously concluded in D342084 that the goat metabolism 

study is adequate in supporting the registered uses of thifensulfuron methyl residues on cereal 

grains, and soybeans. This conclusion is based on the low level of transfer of thifensulfuron 

methyl residues to goat matrices, and the lack of detectable residues in livestock feed items, even 

at exaggerated application rates. HED also concluded that, because no detectable residues of 

thifensulfuron methyl were found in poultry feed items, a poultry metabolism study is not 

required. HED has determined that the ROC in livestock commodities is thifensulfuron methyl

for the purposes of tolerance expression, and risk assessment. The current petition does not alter 

HED’s earlier conclusions regarding livestock metabolism. 

860.1340 Residue Analytical Methods

Residue Chemistry Memo D342084; D. Dotson; 17 April 2008 (PP#7F7219)

Residue Chemistry Memo D311607; S. Ary; 4 January 2005

Residue Chemistry Memo D301488; S. Ary; 12 August 2004

Residue Chemistry Memo D301509; J. Facey; 10 June 2004 (Metabolism Decision Document)

Enforcement methods: Two HPLC photo-conductivity detection methods (Methods 

AMR-646-86 and AMR-761-87) are available for enforcing tolerances for residues of 
Thifensulfuron Methyl Summary of Analytical Chemistry and Residue Data DP Barcode D361945

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thifensulfuron methyl in cereal grains and straw. For Method AMR-646-86, straw samples are 

extracted with ethyl acetate, and the extract is partitioned with sodium bicarbonate. The aqueous 

phase is acidified, and partitioned with dichloromethane. The dichloromethane phase is 

evaporated to dryness, and then reconstituted for analysis via HPLC with photo-conductivity

detection. For Method AMR-761-87, wheat grain is extracted with ethyl acetate, barley grain is 

extracted with 0.1 M sodium bicarbonate, and straw is extracted with ethyl acetate/HCl (at pH 3). 

Extracts are then analyzed via HPLC with photo-conductivity detection. 

An LC/MS method (DuPont Method 1381) is also available for enforcing tolerances for 

residues of thifensulfuron methyl in canola, cotton, and flax commodities. For this method, 

samples are extracted with an acetonitrile/ammonium carbonate buffer solution, and the 

concentrated residues are reconstituted in methanol for analysis. If required, a hexane wash step,

or cleanup step using a strong anion exchange solid phase extraction (SPE) column, may be 

incorporated. Analysis is performed via column-switching LC. Extracts in methanol are applied 

to a size exclusion chromatography column, and the eluate is diverted onto a reversed phase 

XDB-C8 column for MS analysis. The validated LOQ was 0.020 ppm. This method may also be 

used for enforcing tolerances in corn grain, sorghum grain, and soybean seeds. 

Data collection method: Samples collected from the safflower field trial and processing 

studies were analyzed for residues of thifensulfuron methyl using an HPLC photo-conductivity

method (DuPont Method AMR-973-87). The method was adequate for data collection, based on 

acceptable method validation and concurrent method recoveries. Fortification levels were 

adequate to bracket residues found in treated samples. The lowest limit of method validation 

(LLMV) was 0.050 ppm in each matrix. The calculated LOQs were 0.027 ppm in safflower 

seeds, 0.039 ppm in meal, and 0.0068 ppm in oil. The calculated limits of detection (LODs) 

were 0.009 ppm in seeds, 0.013 ppm in meal, and 0.0023 ppm in oil. 

Conclusions: The available residue analytical method data are adequate to satisfy data 

requirements. The existing tolerance enforcement methods, AMR-646-86, AMR-761-87, and 

DuPont Method 1381, are adequate to enforce the proposed tolerance in safflower seeds, and 

DuPont Method AMR-973-87 is adequate for data collection purposes. 

860.1360 Multiresidue Methods

Residue Chemistry Memo D301488; S. Ary; 12 August 2004 

Residue Chemistry Memo CB2354; C. Deyrup; 10 March 1988

The FDA’s PESTDATA database, dated June 2005 (PAM Volume I, Appendix I) does not 

contain any information regarding the recovery of thifensulfuron methyl using multiresidue 

methods. Data investigating the behavior of thifensulfuron methyl using the FDA Multiresidue 

Methods have been submitted by the petitioner (MRID #40429701). Because thifensulfuron 

methyl is thermally labile, only Multiresidue Protocol A was investigated. It was determined that 

thifensulfuron methyl does not give a sufficient response on the required HPLC system 

(D301488; S. Ary; 12 August 2004). The available data indicate that residues of thifensulfuron 

methyl are not recovered by the FDA multiresidue methods. 
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860.1380 Storage Stability

Residue Chemistry Memos D330702 and D330813; S. Hummel; 8 August 2006

Residue Chemistry Memo D301488; S. Ary; 12 August 2004 

Residue Chemistry Memo PP#8G3602; R. Loranger; 18 May 1988

Residue Chemistry Memo PP#6F3431; C. Deyrup; 24 December 1987

The storage durations and conditions of commodity samples collected from the safflower

field trial and processing studies are listed in Table 4, below. To validate sample storage 

conditions and durations, a concurrent storage stability study was conducted. Control samples of 

safflower seeds, meal and oil were fortified with thifensulfuron methyl at 0.10 ppm, followed by

frozen storage of the fortified samples for the duration of the analysis of the field trial samples. 

At the end of the analytical phase, the storage stability samples were analyzed for residues of 

thifensulfuron methyl. The overall average corrected recoveries were 92% from safflower seeds, 

97% from safflower meal, and 108% from safflower oil. Although there was no zero-day

analysis of fortified samples, the storage stability data are adequate, and support the storage 

conditions and durations incurred in the field trial and processing studies. 

TABLE 4 Summary of Storage Conditions and Durations of Samples from the Safflower Field Trial 

and Processing Studies. 

Matrix Storage 

Temperature (°C)

Actual Storage Duration 

(Days)

Interval of Demonstrated Storage 

Stability (Days)

Safflower seeds -26 to -14 608-632 631

Safflower meal 567 584

Safflower oil 561 588

Additional storage stability data are available from previous submissions. These data 

indicate that thifensulfuron methyl is stable under frozen storage conditions for intervals of at 

least 4 months in corn stover and soybean seeds, 14 months in cotton seeds and cotton gin 

byproducts, 24 months in corn grain and forage, and wheat straw, and 36 months in wheat grain. 

Conclusions: The available storage stability data adequately support the sample storage 

durations incurred in the safflower field trial and processing studies. No storage stability

corrections need to be applied to the safflower field trial and processing study results. 

860.1400 Water, Fish, and Irrigated Crops

There are no proposed or registered uses that are relevant to this guideline topic.

860.1460 Food Handling

There are no proposed or registered uses that are relevant to this guideline topic.
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860.1480 Meat, Milk, Poultry, and Eggs

According to OPPTS Residue Chemistry Test Guideline 860.1000, Table 1 Feedstuffs 

(June 2008), safflower meal is the only animal feedstuff associated with the current petition. 

Safflower meal may constitute up to 5% of beef cattle diet, 10% of dairy cattle diet, 25% of 

poultry diet, and 5% of swine diet. In consideration of the proposed regional use of 

thifensulfuron methyl on safflower, and the observed residues of <0.050 ppm in safflower meal, 

the potential contribution to the maximum reasonably balanced dietary burdens of livestock is 

negligible. Therefore, tolerances in meat, milk, poultry and eggs are not required for this 

petition. 

860.1500 Crop Field Trials

DER for MRID #47641801 (CFTs with Safflower)

Three safflower field trials were conducted in Zones 5 (SD) and 7 (ND; 2 trials) during 

the 2000 growing season. At each site a 75% ai DF formulation of thifensulfuron methyl was 

applied to safflower as a single broadcast foliar application, either 81 or 36 days prior to harvest, 

at rates of 0.0176-0.0187 lb ai/A (roughly 1X the proposed rate). Applications were made using 

ground equipment, in spray volumes of 15-19 GPA, and included the use of an NIS adjuvant. 

Duplicate control and treated samples of safflower were harvested 81 days after treatment (DAT) 

from two ND field trials, and 36 DAT from the SD field trial. 

Samples of safflower seeds were analyzed for residues of thifensulfuron methyl using an 

adequate HPLC photo-conductivity method (DuPont Method AMR-973-87). The method was 

adequate for data collection, based on acceptable method validation and concurrent method 

recoveries. Fortification levels were adequate to bracket residues found in treated samples. The 

LLMV was 0.050 ppm, while the calculated LOQ and LOD were 0.027 and 0.009 ppm, 

respectively. 

Safflower seed samples were stored for up to 632 days prior to analysis. The sample 

storage conditions and durations for safflower seeds are supported by adequate concurrent 

storage stability data. 

The results indicate that following one broadcast foliar application of thifensulfuron 

methyl (75% ai DF) to safflower, at rates of 0.0176-0.0187 lb ai/A, residues in safflower seeds 

were <0.050 ppm for all 6 samples harvested at either 81 DAT or 36 DAT (see Table 5, below). 

Although the treatment rate at the SD trial was under-applied by 7%, and samples were harvested 

more than 40 days earlier than the other field trials, this application error will have no impact on 

the adequacy of the field trials, as all residues were <0.050 ppm. A residue decline study was not 

conducted. 
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TABLE 5 Summary of Residue Data from Safflower Field Trials with Thifensulfuron Methyl. 

Commodity Total Use Rate

(lb ai/A)

PHI 

(Days)

Residue Levels (ppm)

n Min. Max. HAFT* Median Mean Std. Dev.

Safflower 

Seed

0.0176-0.0187 36-81 6 <0.05 <0.05 <0.05 <0.05 <0.05 0

* HAFT = Highest Average Field Trial result. 

Conclusions: The residue data for safflower seeds are adequate to fulfill data 

requirements for the proposed use. Although the field trials were conducted with a 75% ai DF 

formulation of thifensulfuron methyl, the number and location of the field trials support the 

requested regional use of Harmony® SG on safflower. The data reflect the proposed use pattern 

(maximum use rate of 0.019 lb ai/A, a PHI of 81 days, and use of an NIS in the spray mixture). 

HED concludes that the proposed tolerance of 0.05 ppm is appropriate. 

860.1520 Processed Food and Feed

DER for MRID #47641801 (PFF from Safflower Seeds)

To generate samples to be used for processing, one trial was conducted in ND during the 

2000 growing season. Safflower seeds were harvested 81 days following a single broadcast 

foliar application of the 75% ai DF formulation, at a rate of 0.0186 lb ai/A (roughly 1X the 

proposed rate). The application was made using ground equipment in a spray volume of 15 

GPA, and included the use of an NIS. The safflower seed samples were processed into meal and 

refined oil using simulated commercial practices. 

Samples of safflower seed, meal and refined oil were analyzed for residues of 

thifensulfuron methyl using an adequate HPLC photo-conductivity method (DuPont Method 

AMR-973-87). The method was adequate for data collection, based on acceptable method 

validation and concurrent method recoveries. Fortification levels were adequate to bracket 

residues found in treated samples. The LLMV in each matrix was 0.050 ppm. The calculated 

LOQs were 0.027 ppm in seed, 0.039 ppm in meal, and 0.0068 ppm in oil, while the calculated 

LODs were 0.009 ppm in seed, 0.013 ppm in meal, and 0.0023 ppm in oil. 

Samples of safflower seed were stored frozen for up to 608 days, while processed 

samples of meal and oil were stored frozen for up to 567 and 561 days, respectively, prior to 

analysis. The storage durations are supported by adequate storage stability data, which were 

generated concurrently with the safflower field trial and processing studies. 

Residues of thifensulfuron methyl were below the LLMV (<0.050 ppm) in safflower seed 

RAC samples harvested 81 days after treatment at a rate of 0.0186 lb ai/A (1X the field trial 

application rate). Following processing, residues of thifensulfuron methyl were <0.050 ppm in 

safflower meal and refined oil processed from treated safflower seed. Processing factors could 

not be calculated because residues were below the LLMV in both the RAC and the processed 

fractions. The theoretical processing factors for safflower meal and oil are 9.1X and 3.3X, 

respectively (OPPTS Residue Chemistry Test Guideline 860.1520, Table 3). 
Thifensulfuron Methyl Summary of Analytical Chemistry and Residue Data DP Barcode D361945

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Conclusions: The submitted safflower processing study showed that residues of

thifensulfuron methyl were <0.050 ppm in safflower meal, and refined oil, processed from 

safflower seeds treated at 1X. Thifensulfuron methyl is not expected to concentrate in safflower 

oil because it has a very low octanol/water partition coefficient (Log KOW = 0.027). It has been 

shown in the cotton processing study (MRID #45098405) that, after treatment at an exaggerated 

rate of 0.094 lb ai/A (roughly 4X the normal use rate of 0.025 lb ai/A), applied one day after 

planting, with a 133-day PHI, residues of thifensulfuron methyl were non-detectable (<0.006 

ppm) in undelinted cotton seeds. As with cotton, the PHI for safflower following treatment with 

thifensulfuron methyl is relatively long (81 days). Cotton seeds, like safflower seeds, may be 

processed into oil or meal, and as such, thifensulfuron methyl is not expected to concentrate in 

safflower processed food/feed items. Also, the requirement for processing studies in canola and 

flax has previously been waived, based on the results of the cotton study. Therefore, a 5X 

processing study is not required in safflower. 

860.1650 Submittal of Analytical Reference Standards

An analytical standard for thifensulfuron methyl is currently available in the NPSR, via

personal communication with Dallas Wright, of the Biological and Economic Analysis 

Division’s Analytical Chemistry Branch (BEAD/ACB), on 27 July 2009. Analytical reference 

standards should be replenished as requested by the Repository. The reference standards should 

be sent to the ACB, which is located at Fort Meade, to the attention of Theresa Cole at the 

following address: 

USEPA

National Pesticide Standards Repository/Analytical Chemistry Branch/OPP

701 Mapes Road

Fort George G. Meade, MD 20755-5350

(Note that the mail will be returned if the extended zip code is not used.)

860.1850 Confined Accumulation in Rotational Crops

860.1900 Field Accumulation in Rotational Crops

Residue Chemistry Memo D342084; D. Dotson; 17 April 2008 (PP#7F7219)

Confined rotational crop studies have previously been submitted. These studies were 

initially reviewed by EFED, and were deemed inadequate pending submission of additional data

and information to upgrade the acceptability of a greenhouse confined rotational crop study with 

[triazine-2-

14C]-thifensulfuron methyl. The requested data and information have been submitted 

and reviewed by HED. HED concluded that although the data are not fully adequate, a new 

confined rotational crop study will not be required because of the nature of the pesticide. It is 

unlikely that additional ROCs would be found if the study were repeated. No field rotational 
Thifensulfuron Methyl Summary of Analytical Chemistry and Residue Data DP Barcode D361945

Page 13 of 15

crop studies have been submitted for thifensulfuron methyl, and none are required for this 

petition. The 45-day PBI on the product label for Harmony® SG is adequate. 

860.1550 Proposed Tolerances

HED has previously determined that the ROC in plant commodities is thifensulfuron 

methyl for the purposes of tolerance expression, and risk assessment. Permanent tolerances are 

established for thifensulfuron methyl in/on barley, canola, corn, cotton, flax, oat, rice, sorghum, 

soybean and wheat commodities, at levels ranging from 0.02 to 2.5 ppm (40CFR §180.439[a]). 

The subject petition proposes a tolerance for “combined” residues of the herbicide thifensulfuron 

methyl in/on safflower, seed (RAC) at 0.05 ppm. A revised Section F should be submitted to 

delete the word “combined” from the tolerance expression. 

The safflower field trial data are adequate to support a regional tolerance of 0.05 ppm in

safflower seeds grown in North Dakota, South Dakota, Nebraska, Montana (east of Route 87 or 

east of I-15), and Wyoming (east of I-25 or north of I-90). All safflower seeds bore residues 

below the LLMV (<0.050 ppm) following application of a 75% ai DF formulation according to 

the proposed rate and PHI. No tolerances are required for residues of thifensulfuron methyl in 

animal commodities, nor in rotational crops, for the purposes of this petition. 

A summary of the proposed and recommended tolerances is presented in Table 6, below. 

There are no established or proposed Codex Maximum Residue Limits (MRLs) for 

residues of thifensulfuron methyl. Canada and Mexico have established MRLs for thifensulfuron 

methyl in several plant commodities. The ROCs in Canada, Mexico and the US are harmonized. 

However, no Canadian or Mexican MRLs for thifensulfuron methyl have been proposed or 

established in safflower seed. An International Residue Limit Status sheet is appended to this 

document. 

TABLE 6 Tolerance Summary for Thifensulfuron Methyl. 

Commodity Proposed Tolerance 

(ppm)

Recommended 

Tolerance (ppm)

Comments; Correct Commodity 

Definition

Safflower, seed 0.05 0.05
Thifensulfuron Methyl Summary of Analytical Chemistry and Residue Data DP Barcode D361945

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References

PP #7F7219 Label Amendments and Petition for Tolerances on Wheat Forage and Hay, 

Oat Forage and Hay, and Barley Hay. Summary of Analytical Chemistry and Residue Data.; 

D342084; D. Dotson; 17 April 2008. 

Thifensulfuron Methyl. Addition of Uses on Rice and Sorghum (PRIA R19 - 352-611; 

PP#4F6889). Summary of Analytical Chemistry and Residue Data.; D330702 and D330813; S. 

Hummel; 8 August 2006. 

Thifensulfuron Methyl. HED’s Response to E.I. du Pont de Nemours and Company’s 

Comments to the “Summary of Residue Chemistry Data Evaluation Records for the 

Establishment of Tolerances for New Uses of Thifensulfuron Methyl on Canola, Flax, and 

Cotton.”; D311607; S. Ary; 4 January 2005. 

Thifensulfuron Methyl. Summary of Residue Chemistry Data Evaluation Records for the 

Establishment of Tolerances for New Uses of Thifensulfuron Methyl on Canola, Flax, and 

Cotton.; D301488; S. Ary; 12 August 2004. 

Thifensulfuron Methyl. Meeting Report of the Metabolism Assessment Review Committee 

Document. TXR Number 0052419; D301509; J. Facey; 10 June 2004. 

PP#8G3602, 352-EUP-RUL. DPX-M316 (Pinnacle) on Soybeans. Evaluation of 

Analytical Method and Residue Data; R. Loranger; 18 May 1988. 

PP #6F3431. Response (2 December 1987) by E.I. Du Pont de Nemours & Co. to the 

Need for Testing DPX-H6573 (HarmonyTM) with Multiresidue Protocols. (RCB #22354); 

CB2354; C. Deyrup; 10 March 1988. 

PP #6F3431. Response (14 September 1987) by E.I. Du Pont de Nemours & Co. to the 

Data Gaps Identified in the Product Chemistry Chapter and Residue Chemistry Chapter of the 

2/87 Harmony (DPX-M6316) Registration Standard. (RCB #2825); C. Deyrup; 24 December 

1987. 
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Appendix 1 - International Residue Limit Status Sheet

INTERNATIONAL RESIDUE LIMIT STATUS

CAS Name: 3-[[[[(4-methoxy-6-

methyl-1,3,5-triazin-2-yl)

amino]carbonyl]amino] sulfonyl]-2-

thiophenecarboxylic acid

Common Name: 

Thifensulfuron 

methyl

X Proposed tolerance

⁮ Reevaluated tolerance

⁮ Other

Date: 27 July 

2009

Codex Status (Maximum Residue Limits) US Tolerances

X No Codex proposal step 6 or above

□ No Codex proposal step 6 or above for the crops 

requested

Petition Number: 9F7523

DP Barcode: D361945

Other Identifier: PC Code 128845

Residue definition (step 8/CXL): Reviewer/Branch: William T. Drew/RAB2

Residue definition: Thifensulfuron methyl

Crop(s) MRL (mg/kg) Crop Tolerance (ppm)

Safflower, seed 0.05

Limits for Canada Limits for Mexico

⁮ No Limits

X No Limits for the crops requested

⁮ No Limits

X No Limits for the crops requested

Residue definition: Methyl-3-[[[[(4-methoxy-6-methyl1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]-2-

thiophenecarboxylate

Residue definition: Thifensulfron methyl

Crop(s) MRL (mg/kg) Crop(s) MRL (mg/kg)

Notes and/or special instructions: per Steve Funk, 27 July 2009.