Document ID: EPA-HQ-OPP-2008-0125-0008
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-02-02T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

	OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date:		28-MAY-2010

Subject:	Sulfentrazone.  Section 3 Registration Request to Add New Uses
on:  Brassica, Head and Stem, Subgroup 5A; Brassica, Leafy Greens,
Subgroup 5B; Melon, Subgroup 9A; Fruiting Vegetable, Group 8 and Okra;
Pea, Succulent; Flax; Strawberry; and Tuberous and Corm Vegetable,
Subgroup 1C.  Amendment of 08/12/2009.

PC Code:  129081	DP Barcode:  D368179

Decision No.:  388050	Registration Nos:  279-3220 & 279-3189

Petition No.:  7E7308	Regulatory Action:  Amended Section 3

Risk Assessment Type:  NA	Case No.:  7231

TXR No.:  NA	CAS No.:  122836-35-5

MRID No.:  None	40 CFR:  §180.498

From:		William D. Wassell, Chemist

		Risk Assessment Branch 1 (RAB1)

		Health Effects Division (HED, 7509P)

Through:	George F. Kramer, Ph.D., Senior Chemist

		RAB1/HED (7509P)

To:		Daniel Rosenblatt, RM 05

	Registration Division (RD, 7505P) 

Executive Summary

  SEQ CHAPTER \h \r 1 Sulfentrazone is an aryl triazolinone herbicide
used to control a variety of broadleaf weeds.  The mode-of-action for
controlling emerging weeds is by protoporphyrinogen oxidase (PPO)
inhibition.  Plants emerging from soils treated with sulfentrazone turn
necrotic and die shortly after exposure to light.

The Interregional Research Project No. 4 (IR-4) has submitted a petition
proposing the establishment of permanent tolerances for the combined
residues of the herbicide sulfentrazone
[N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2
,4-triazol-1-yl]phenyl]methanesulfonamide] and its metabolites HMS
[N-(2,4-dichloro-5-(4-(difluoromethyl)-4,5-dihydro-3-hydroxymethyl-5-oxo
-1H-1,2,4-triazol-yl)phenyl)methanesulfonamide)], and DMS [(N-2,4-
dichloro-5-[4-(difluoromethyl)-4,5-dihydro-5-oxo-1H-1,2,4-triazol-1-yl)p
henyl)methanesulfonamide] in/on:

Brassica, head and stem, subgroup 5A*	0.20 ppm

Brassica, leafy greens, subgroup 5B	0.35 ppm

Melon, subgroup 9A	0.10 ppm

Vegetable, fruiting, group 8	0.05 ppm

Okra	0.05 ppm

Pea, succulent	0.05 ppm

Flax	0.05 ppm

Strawberry	0.05 ppm

Vegetable, tuberous and corm, subgroup 1C*	0.15 ppm

	*  Individual tolerances are established for residues in/on cabbage at
0.20 ppm and potato at 0.15 ppm.

The current submission consists of a letter (dated:  08/12/2009) from
Dan Kunkel of the IR-4 program and addresses deficiencies cited HED’s
review of the subject petition (Memo, 9/29/08, W.D. Wassell, D349321).

  SEQ CHAPTER \h \r 1 Regulatory Recommendations and Residue Chemistry
Deficiencies

There are no residue chemistry issues that would preclude granting an
unconditional registration for the requested uses pending submissions of
a revised Section B (see requirements under Directions for Use);
reference standard for the metabolite HMS (see requirements under   SEQ
CHAPTER \h \r 1 Submittal of Analytical Reference Standards); and a
revised Section F (see Table 1).  The proposed uses and the submitted
data support the establishment of the following permanent tolerances for
residues of the herbicide sulfentrazone, including its metabolites and
degradates, in or on the commodities listed below.  Compliance with the
tolerance levels specified below is to be determined by measuring only
the sum of sulfentrazone
(N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2
,4-triazol-1-yl]phenyl]methanesulfonamide) and its metabolites HMS
(N-(2,4-dichloro-5-(4-(difluoromethyl)-4,5-dihydro-3-hydroxymethyl-5-oxo
-1H-1,2,4-triazol-1-yl)phenyl)methanesulfonamide) and DMS
(N-(2,4-dichloro-5-(4-(difluoromethyl)-4,5-dihydro-5-oxo-1H-1,2,4-triazo
l-1-yl)phenyl)methanesulfonamide, both free and conjugated, calculated
as the stoichiometric equivalent of sulfentrazone.

Brassica, head and stem, subgroup 5A	0.20 ppm

Brassica, leafy greens, subgroup 5B	0.40 ppm

Melon, subgroup 9A	0.15 ppm

Vegetable, fruiting, group 8	0.15 ppm

Okra	0.15 ppm

Pea, succulent	0.15 ppm

Flax	0.15 ppm

Strawberry	0.15 ppm

Vegetable, tuberous and corm, subgroup 1C	0.15 ppm

Detailed Considerations:

The previously noted deficiencies are summarized below, followed by the
petitioner’s response and finally HED conclusions.

860.1200 Directions for Use

A revised Section B is required.  The proposed label for Spartan® 4F
Herbicide (EPA Reg. No. 279-3220), a 4 lb/gal FlC formulation, should be
modified to correct the application rates listed as “dry ounces
Spartan® Herbicide per acre” to “fluid ounces Spartan® Herbicide
per acre.”  Also, as metabolism data are not available to support
postemergence applications on fruiting vegetables, these proposed uses
should be limited to preemergence application only.  Additionally, the
proposed labels should be revised to specify a maximum single and
seasonal application rate of 0.020 lb ai/A for Spartan® to Brassica
leafy greens subgroup 5B as this rate is supported by the submitted crop
field trial data for mustard greens.  

Petitioner’s Response:  None.

HED Conclusions:  This deficiency remains outstanding.

860.1520 Processed Food and Feed

New flax and tomato processing studies should be submitted.  Since
phytotoxicity does not appear to be an issue, the requested processing
studies should use an exaggerated application rate (equal to the maximum
theoretical concentration factor or 5x, whichever is less).

The submitted flax and tomato processing studies are unacceptable since
the studies did not conclusively demonstrate that sulfentrazone residues
of concern will not concentrate in processed fractions as a result of
the proposed use.  Quantifiable residues were not detected in the RACs
used for processing, and the field trials were conducted at only 1x
(flax) or 2x (tomatoes) rates.  Since phytotoxicity does not appear to
be an issue, the processing studies need to be repeated using an
exaggerated application rate (equal to the maximum theoretical
concentration factor or 5x, whichever is less).

Petitioner’s Response:  For both flax and tomato, IR-4 decided to
forego 5x exaggerated studies due to concerns of phytotoxicity, delayed
fruit set, and uncertainty concerning producing commodities with
quantifiable residues.  With regard to flax, phytotoxicity was of less
concern, but the long pre-harvest interval makes it unlikely that
residues would be present regardless of the application rate.  With
regard to tomato, IR-4 had considerable concern for crop phytotoxicity
that precluded IR-4 from providing a study above the 2x rate.  These
considerations were based on available crop injury data as well as
delayed crop maturity from transplant applications.  IR-4 concludes that
the 2x study along with the processing study, clearly demonstrates that
no residues will be in tomato processed commodities.  IR-4 further
doubts whether it would even be possible to produce a marketable crop at
the requested 5x rate.  

HED Conclusions:  Concerning flax, HED has accepted sulfentrazone
processing studies without an exaggerated rate for other crops with a
similar use pattern such as field corn (Memo, 11/26/2002, G.F. Kramer,
D276112) and sunflowers (Memo, 1/10/2003, G.F. Kramer, D286879) based on
concerns for phytotoxicity and the inability to provide samples with
detectable residues.  HED concludes that an additional flax processing
study is not required.

Concerning tomato, phytotoxicity was a problem in some of the submitted
field trials and we defer to IR-4’s expertise concerning the
likelihood of being able to conduct an exaggerated rate study (above
2x).  HED concludes an additional tomato processing study is not
required.  

Note to IR-4:  Taking into account that HED usually asks for exaggerated
rate field trials in conjunction with processing studies when
quantifiable residues are not present at 1x, IR-4 should have included
the discussion of why it was not possible to do exaggerated rate studies
in the original submission.  

  SEQ CHAPTER \h \r 1 860.1650 Submittal of Analytical Reference
Standards

As the reference standard for the metabolite HMS has expired 4/1/2008,
the petitioner must submit a new standard.  If new standards are being
submitted, they should be sent to the Analytical Chemistry Lab, 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

Petitioner’s Response:  None.

HED Conclusions:  This deficiency remains outstanding.

860.1550 Proposed Tolerances

A summary of recommended tolerances are presented in the following
table.  The petitioner is required to submit a revised Section F to
reflect appropriate tolerance levels.

Table 1.  Tolerance Summary for Sulfentrazone.

Commodity	Proposed Tolerance (ppm)	Recommended Tolerance (ppm)	Comments

Brassica, head and stem, subgroup 5A	0.20	0.20	The established tolerance
for cabbage under 180.498(a)(2) should be removed concomitantly when the
subgroup 5A tolerance is established

Brassica, leafy greens, subgroup 5B	0.35	0.40

	Melon subgroup 9A	0.10	0.15

	Vegetable, fruiting, group 8	0.05	0.15

	Okra	0.05	0.15

	Pea, succulent	0.05	0.15

	Flax	0.05	0.15	The established time limited tolerance for flax seed
under 180.498(b) should be removed concomitantly when the permanent flax
tolerance is established.

Strawberry	0.05	0.15	The established time limited tolerance for
strawberry under 180.498(b) should be removed concomitantly when the
permanent strawberry tolerance is established.

Vegetable, tuberous and corm, subgroup 1C	0.15	0.15	Tolerance
recommendation is based on residue data translated from potato.  The
established tolerance for potato under 180.498(a)(2) should be removed
concomitantly when the subgroup 1C tolerance is established.

Petitioner’s Response:  None.

HED Conclusions:  This deficiency remains outstanding.

RDI:  RAB1 Chemistry Team:  02/24/2010

Petition Number:  7E7308

DP#:  368179

PC Code:  129081

Sulfentrazone	Summary of Analytical Chemistry and Residue Data	DP#: 
368179

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