UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, DC  20460

OFFICE OF PREVENTION,

PESTICIDES AND TOXIC SUBSTANCES

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date:	19 January 2010

SUBJECT:	Thifensulfuron Methyl.  Petition   SEQ CHAPTER \h \r 1 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.  

™ Harmony® SG



FROM:	William T. Drew, Chemist  SEQ CHAPTER \h \r 1 

		Risk Assessment Branch 2 (RAB2)

		Health Effects Division (HED), 7509P

THRU:	Dennis McNeilly, Chemist

		RAB2/HED, 7509P

TO:		Barbara Madden, RM Team 5  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r
1 

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

		Registration Division (RD), 7505P

  SEQ CHAPTER \h \r 1 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.

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-triazin-2-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

ont™ 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
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,   SEQ CHAPTER \h \r 1 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 non-detectable (<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.  

	  SEQ CHAPTER \h \r 1 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.  

  SEQ CHAPTER \h \r 1 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).  

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.

 DuPont™ Harmony® GT XP, EPA Registration #352-446

Proposed use:  50% ai SG, DuPont™ 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; D.
Dotson; 17 April 2008)

pH	4.0

	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

	Vapor pressure (25ºC)	1.7 x 10-8 Pa (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 DuPont™ 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 I-15), 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.  

	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 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.
 

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.

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.  

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   SEQ CHAPTER \h \r 1 processed from
treated safflower seed.  Processing factors could not be calculated  
SEQ CHAPTER \h \r 1 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).  

	Conclusions:  The submitted safflower processing study showed that
residues of thifensulfuron methyl were <0.050 ppm in safflower meal, and
refined oil,   SEQ CHAPTER \h \r 1 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.  

  SEQ CHAPTER \h \r 1 860.1650 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 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

	



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 (Harmony™) with Multiresidue
Protocols.  (RCB #22354); CB2354; C. Deyrup; 10 March 1988.  

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(DPX-M6316) Registration Standard.  (RCB #2825); C. Deyrup; 24 December
1987.  



Appendix 1 - International Residue Limit Status Sheet

INTERNATIONAL RESIDUE LIMIT STATUS

CAS Name:
†ⴳ孛孛㐨洭瑥潨祸㘭洭瑥票⵬ⰱⰳⴵ牴慩楺⵮ⴲ汹 
浡湩嵯慣扲湯汹慝業潮⁝畳晬湯汹ⵝⴲ桴潩桰湥捥牡潢
祸楬⁣捡摩䌇浯潭⁮慎敭›吠楨敦獮汵畦潲⁮敭桴汹܍
⁘†牐灯獯摥琠汯牥湡散

⁮   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

ô

⁮  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-methyl-1,3,5-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.  



Page   PAGE  1  of   NUMPAGES  15 

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

