Document ID: EPA-HQ-OPP-2006-0321-0007
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2007-02-28T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

MEMORANDUM

	Date:	8 August 2006

	Subject:	Sethoxydim:  Response to Petitions for Tolerance on Borage,
Buckwheat, Dill, Okra, Radish and Turnip Greens, Summary of Analytical
Chemistry and Residue Data PP # 4E6885 and PP # 0E6204, Summary of
Analytical Chemistry and Residue Data.  

	

DP Barcode:	

  327825 and 327826	

Decision No.:	

353644

PC Code:	121001	

   Petition:	

PP # 4E6885, PP # 0E6204

40 CFR 180.412	

	

MRID Nos.:	

46417301 - 46417305

	From:	David Soderberg, Chemist

		RRB3, Health Effects Division (7509P)

	Through:	William Donovan, Senior Chemist

		RRB3, Health Effects Division (7509P)

		Leung Cheng, Senior Chemist

		RAB3, Health Effects Division (7509P)

	To:	Daniel Rosenblatt, Chemical Manager

		Herbicides, Registration Division, (7505P)

Executive Summary

[This document contains original regulatory decisions, but most of the
information and much of the discussion are cut and pasted from other
agency documents, with some minor changes, and are not original to this
reviewer.]

This memorandum transmits regulatory responses to a petition for
tolerances for five crops (borage, buckwheat, okra, dill, and radish). 
The petition was submitted in PP # 4E6885.  This memorandum also
responds to submission of field trial studies for application of
sethoxydim to these five crops, and to processing studies for two of
those crops (buckwheat and dill).  These studies were submitted in
support of PP # 4E6885. The five field trials were submitted in MRIDs
46417301 (buckwheat), 46417302 (okra), 46417303 (borage), 46417304
(dill) and 46417305 (radish).  MRIDs 46417301 (buckwheat) and 46417304
(dill) included the processing studies.  This memorandum also responds
to a petition for tolerance on turnip greens to be translated from
surrogate data.  The turnip petition was submitted in PP # 0E6204.

  

The qualitative nature of the sethoxydim residue in plants is adequately
understood based on soybean, tomato and sugar beet metabolism studies. 
The nature of the residue in livestock is understood based on acceptable
metabolism studies in ruminants (goat) and poultry (hens). The residues
of concern for tolerances and risk assessment in plants and livestock
are the combined residues of sethoxydim and its metabolites containing
the 2-cyclohexen-1-one moiety (calculated as sethoxydim).  These are
measured by GC/MS following oxidation and methylation.  For risk
assessment purposes the residues in water are parent and degradates.  

Tolerances have been established under 40 CFR §180.412 for the combined
residues of sethoxydim
[2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen
-1-one] and its metabolites containing the 2-cyclohexen-1-one moiety
(calculated as sethoxydim) in or on numerous agricultural commodities. 
Permanent tolerances are established (40 CFR §180.412) for residues of
the herbicide sethoxydim and its metabolites containing the
2-cyclohexen-1-one moiety in meat and fat of cattle, goats, hogs,
horses, poultry, and sheep at 0.2 ppm; meat byproducts of cattle, goats,
hogs, horses, poultry, and sheep at 1.0 ppm (except 2.0 ppm in poultry,
mbyp); eggs at 2.0 ppm, and milk at 0.5 ppm.  The tolerance expression
for plant and livestock commodities includes the combined residues of
sethoxydim and its metabolites containing the 2-cyclohexen-1-one moiety
(calculated as the herbicide) as specified in 40 CFR §180.412 and as
measured above.

This submission supports additional tolerances on okra (2.5 ppm), borage
(6 ppm) and its meal (10 ppm), fresh dill (10 ppm), buckwheat (19 ppm)
and buckwheat flour (25 ppm), and radish tops (4.5 ppm).  The data
support creation of a crop group 1 tolerance for roots and tubers (4.0
ppm) that includes radish roots as well as including other roots and
tubers that currently have tolerances: carrots, horseradish, sugar
beets, and garden beets, tuberous and corm vegetable crop subgroup 1D. 
Based upon a translation from Brassica, turnip greens can be assigned a
tolerance of 5 ppm.

		

BASF Wyandotte Corporation's (BWC's) Methods No. 30, 30G, 30H and A9003
have been determined to be adequate analytical methods for data
collection and/or enforcement of tolerances for residues of sethoxydim
and its metabolites in or on plant and livestock commodities.  In these
methods, residues are extracted with water/methanol in various ratios,
and the extract is crudely cleaned up with alkaline precipitation and
partitioning.  Then the residues are oxidized with peroxide, further
cleaned up, and then derivatized to two dimethyl esters:
3-[2-(ethylsulfonyl) propyl]-pentanedioic acid dimethyl ester (DME) and
3-[2-(ethylsulfonyl) propyl]-3-hydroxy-pentanedioic acid dimethyl ester
(DME-OH); and the esters are subsequently determined by GC/FPD in the
sulfur mode.   This method has been shown to detect the analytes down to
0.05 ppm in all matrices tested.  

The studies in this submission all use minor modifications of Method 30,
adapted as necessary to each matrix, and are acceptable for data
collection.  Method 30, unmodified, is a PAM II method, and should be
able to stand as the enforcement method for these new crops.

Sethoxydim is generally applied postemergence by ground or aerial
broadcast spray and can also be applied in bands or used as a spot
treatment.  Usually one to three applications are used and in the
current submissions PHIs range from 14 days to 30 days (for turnip
greens) after applications at 0.3 – 0.5 lbs ai/A/application, usually
with a 1 lb ai/A seasonal rate.  

Residue Chemistry Deficiencies

There are no outstanding residue chemistry deficiencies associated with
the proposed new uses.  A human health risk assessment will be
forthcoming.

Background

  SEQ CHAPTER \h \r 1 Sethoxydim is a selective, systemic, postemergence
herbicide used for the control of annual and perennial grass weeds in
broadleaf crops.  Sethoxydim is a member of the cyclohexenone class of
pesticides. Other members of this class include cycloxydim, clethodim,
and tralkoxydim.  Current formulations of sethoxydim include soluble
concentrate (SC) and emulsifiable concentrate (EC).  The active
ingredient (ai) sethoxydim in these formulations ranges from 11.15% to
43%.  Sethoxydim is registered for application to a number of crops. 
Application rates and pre-harvest interval (PHI) requirements vary
depending on the crop. 

Table 1 presents the chemical structure and nomenclature of sethoxydim. 
It also includes the structures of the two important oxidized
metabolites, which are also used as the fortification standards.  In
addition, the structures of the ultimate methylated analytes DME and
DME-OH are shown.  The physicochemical properties of the technical grade
of sethoxydim are presented in Table 2.

Table 1.	Sethoxydim Nomenclature.

Chemical structure	

Common name	Sethoxydim

Company experimental name	BAS 9052 H or BAS 562 05H

IUPAC name
(±)-(EZ)-2-(1-ethoxyiminobutyl)-5-[2-(ethylthio)propyl]-3-hydroxycycloh
ex-2-enone

CAS name
(±)-2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cycloh
exen-1-one

CAS registry number	74051-80-2

End-use product (EP)	1.5 lb/gal EC formulation (Poast® Herbicide; EPA
Reg. No. 7969-58)

Chemical structure of 2-cyclohexen-1-one metabolites	

Derivatized residues determined by the analytical method		

Common and chemical names	DME; 3-[2-(ethylsulfonyl)propyl]-pentanedioic
acid dimethyl ester	DME-OH;
3-[2-ethylsulfonyl)propyl]-3-hydroxypentanedioic acid dimethyl ester

Metabolites used for sample fortification 1		

Common and chemical names	MSO;
2-[1-(ethoxyimino)butyl]-5-[2-(ethylsulfinyl)propyl]-3-hydroxy-2-cyclohe
xen-1-one	5-OH-MSO2;
2-[1-(ethoxyimino)butyl]-5-[2-(ethylsulfonyl)propyl]-3,5-dihydroxy-2-cyc
lohexen-1-one

1  Sethoxydim is readily oxidized to MSO and 5-OH-MSO2 in air;
therefore, these metabolites are used for sample fortification.

TABLE 2.	Physicochemical Properties of  Sethoxydim.  

Property	Description	Reference (MRID#)

Boiling Point	>130º C at 6 x 10-1 mm Hg	41607203

Density, bulk density, or specific gravity	1.058 specific gravity at
20º C	41607203

Solubility	Water at 25º C: 2.57 x 10 2 ppm at pH 5, 4.39 x 10 3 ppm at
pH 7;   

organic solvents (methanol, n-octanol, ethyl acetate, n-hexane, toluene,
xylene, and olive oil) at 20º C: freely soluble (>10 3 g/100 mL).  
41475201

41510601

Vapor pressure	1.6 x 10 -7 mm Hg at 25º C	00047647

Dissociation constant	pKa is 4.6 at pH 4.5 and 25º C	00047650

Octanol/water partition coefficient	Kow is 3.26 x 10 3 at pH 5; 45.1 at
pH 7; 0.93 at pH 9	41475202

pH	3.95 at 20º C	41607203

UV/Visible absorption spectrum

860.1200  Directions for Use

Table 3.  Summary of Directions for Use of Sethoxydim.

Applic. Timing, Type, and Equip.	Formulation

[EPA Reg. No.]	Applic. Rate 

(lb ai/A)	Max. No. Applic. per Season	Max. Seasonal Applic. Rate

(lb ai/A)	PHI

(days)	Use Directions and Limitations

Borage

Postemergence

Broadcast, band, or spot

Ground or aerial	POAST EC 1.5 lbs/gal

7969-58	0.5 lbs ai/A	2	1.0 lbs ai/A	23	See Footnote1

Buckwheat

Postemergence

Broadcast, band, or spot

Ground or aerial	POAST EC 1.5 lbs/gal

7969-58	0.5 lb ai/A	2	1.0 lb ai/A	21	See Footnote1

Dill

Postemergence

Broadcast, band, or spot

Ground or aerial	POAST EC 1.5 lbs/gal

7969-58	0.5 lb ai/A	2	1.0 lb ai/A	14	See Footnote1

Okra

Postemergence

Broadcast, band, or spot

Ground or aerial	POAST EC 1.5 lbs/gal

7969-58	0.3 ai/A, then 0.5 lbs ai/A	3	1.1 lb ai/A	14	See Footnote1

Radish

Postemergence

Broadcast, band, or spot

Ground or aerial	POAST EC 1.5 lbs/gal

7969-58	0.5 lbs ai/A	1	0.5 lb ai/A	14	See Footnote1

Turnip

Postemergence

Broadcast, band, or spot

Ground only.	POAST EC 1.5 lbs/gal

7969-58	0.3 lbs ai/A	1	0.3 lbs ai/A	30	Do not use on turnips grown for
roots.  Do not use tops or roots for livestock grazing or feeding.  No
aerial application.

1.  The master label includes the following general use directions:  (1)
use with spray adjuvants, including crop oil concentrate or
modified/methylated seed oil is recommended; and (2) a 30-day plantback
interval is established for any crop for which there is no registered
use of sethoxydim.  

Conclusions.  The submitted labels are adequate to allow evaluation of
the submitted data for borage, buckwheat, dill, okra, radish, and turnip
tops.  

The submitted crop field trial data are acceptable to support the
proposed PHIs for the individual crops of borage, buckwheat, dill, okra,
radish, and turnip tops.  

860.1300 Nature of the Residue - Plants

HED Chemistry Chapter of the Sethoxydim RED, 6/22/05, W. Donovan

e compounds; very little (≤0.5%) sethoxydim is left unmetabolized. 
The residues of concern in plants are the combined residues of
sethoxydim and its metabolites containing the 2-cyclohexen-1-one moiety
(calculated as sethoxydim).

860.1300 Nature of the Residue - Livestock

There are no livestock feed items associated with the proposed uses;
therefore, data requirements for livestock metabolism data are not
relevant to this tolerance petition.

860.1340 Residue Analytical Methods

HED Chemistry Chapter of the Sethoxydim RED, 6/22/05, W. Donovan

The methods used in these field trials were adapted by minor
modifications from “Determination of BAS 9052H and its Metabolite
Residues in Soybean Seed, Soybean Seed Process Fractions, Chicken
Tissues, Beef Tissues, Milk and Eggs Analytical Method 30 with
modifications 30B, 30G and 30H, BASF Wyandotte Corporation,
1982-1985.”  

Method 30

BWC's Method No. 30, "Determination of BAS 9052H and its Metabolites in
Soybean Seed, Soybean Seed Process Fractions, Chicken Tissues, Beef
Tissues, Milk and Eggs", is designed to determine residues of sethoxydim
and its metabolites, including the parent sulfoxide (MSO), the parent
sulfone (MSO2) and hydroxylated derivatives (e.g. 5-OH-MSO2).  Residues
are determined as 3-[2-(ethylsulfonyl)-propyl] pentanedioic acid
dimethyl ester (DME) and its 3-hydroxy derivative: 3-[2-(ethoxysulfonyl)
propyl]-3-hydroxypentanedioic acid dimethyl ester (DME-OH),
respectively. The limit of quantitation for each analyte is reported to
be 0.05 ppm sethoxydim equivalents.  Method 30 is included as Sethoxydim
Method I in PAM II.  

In Method 30, samples are extracted with aqueous methanol, methanol, or
acetonitrile, depending on the sample matrix.  The sample extracts are
cleaned up by alkaline precipitation, filtration, then acidification and
partitioning into methylene chloride, evaporation to dryness, and
addition of 1% barium hydroxide and oxidation by reflux with hydrogen
peroxide X 25 minutes.  This converts Sethoxydim and its metabolites to
3-[2-(ethoxysulfonyl) propyl] pentanedioic acid and
3-[2-(ethoxysulfonyl) propyl]-3-hydroxypentanedioic acid. The resulting
solutions are purged of peroxide; derivatives are partitioned into
methylene chloride and cleaned up by silica gel column chromatography. 
Some samples require an additional HPLC cleanup on silica.  These
oxidized products are then derivatized to two dimethyl esters:
3-[2-(ethylsulfonyl) propyl]-pentanedioic acid dimethyl ester (DME) and
3-[2-(ethylsulfonyl) propyl]-3-hydroxy-pentanedioic acid dimethyl ester
(DME-OH); and these esters are subsequently determined by GC/FPD in the
sulfur mode at 394 nm.  

Sethoxydim can be unstable to oxidation.  Therefore, recovery samples
were fortified with two oxidation products of sethoxydim.  These
products are
2-[1-(ethoxyimino)butyl]-5-[2-ethylsulfinyl)propyl]-3-hydroxy-2-cyclohex
en-1-one (MSO) and
2-[1-(ethoxyimino)butyl]-5-[2-ethylsulfonyl)propyl]-3,
5-dihydroxy-2-cyclohexen-1-one (5-OH-MSO).  Successful EPA petition
method validation trials were conducted for Method 30 on soybeans, beef
liver, and milk.  In the soybean validation trial, recoveries were
73-85% for sethoxydim and the metabolites MSO2, M2SO2, and 5-OH-MSO2
from duplicate soybean samples fortified with each compound at 0.1 ppm.
The lower limit of method validation (LLMV) of Method 30 is 0.05 ppm
each for MSO and MSO2 for all commodities tested.  This LLMV is correct
for all commodities and all modifications of Method 30 in the current
submission.  Recoveries were generally acceptable.

Calibration curves for the various versions of Method 30 were non-linear
and were instead fitted with quadratic equations.  In some specific
cases some recoveries bordered on, or exceeded, acceptable limits, but
overall recoveries were deemed acceptable for data gathering purposes to
address the needs for each commodity. 

 

860.1360 Multi-residue Methods

It has been shown that sethoxydim is not recovered through any of the
PAM I multi-residue protocols.  

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

Analytical standards for sethoxydim and the sulfoxide (MSO), sulfone
(MSO2), and 5-hydroxysulfone (5-OH-MSO2) metabolites, as well as for the
derivatives DME and DME-OH determined by the analytical method, are
currently available in the National Pesticide Standards Repository.  

860.1380 Storage Stability

In the 2005 Residue Chemistry Chapter of the RED (D312567, W. Donovan
4/22/05) it was reported that HED concluded that non-Craven frozen
storage stability data for sethoxydim and its metabolites in soybean
seeds, tomatoes, apples, oranges, and potatoes are available for up to
36 months and are adequate to profile sethoxydim and its metabolites in
various crops.  For soybean seeds, the data indicate that residues of
parent, MSO2, M2SO2, and 5-OH-MSO2 are stable for only up to 24 months.

Replacement data for that generated by Craven Laboratories, showed that
MSO was stable in corn grain and forage, lettuce, oranges, tomatoes,
cucumbers, succulent and dry beans, potatoes, onions, apples, cherries,
and strawberries for 5 years under frozen storage (<- 5°C).  5-OH-MSO2
was less stable than MSO in acidic matrices: 5-OH-MSO2 was stable in
cherries, strawberries, and tomatoes for 3 years, in succulent beans and
potatoes for 4 years, and in corn grain and forage, lettuce, oranges,
cucumbers, dry beans, onions, and apples for 5 years under frozen
storage.

With the present submissions concurrent storage stability recoveries
(before and after) were performed with the borage, buckwheat, radish,
and dill field trials.  Table 4 presents the range of frozen storage
stability recoveries at the end of storage for each analyte and crop.  

Table 4. Results of concurrent recoveries at the end of the testing
period after frozen storage for the commodities tested in this
submission   

Crop/Commodity	Analyte	Days of Storage	Range of Recoveries

Radish Tops	MSO	135	76-114%

	5-OH-MSO2	135	84-102%

Radish Roots	MSO	299	48-71%

	5-OH-MSO2	299	20-40%

Borage Seed	MSO	203	60-81%

	5-OH-MSO2	203	67-100%

Okra	MSO	131	Not analyzed

	5-OH-MSO2	131	Not analyzed

Dill/Fresh	MSO	370	82-87%

	5-OH-MSO2	370	89-93%

Dill/Dried	MSO	413	85%

	5-OH-MSO2	413	87-88%

Dill Oil	MSO	387	70-82%

	5-OH-MSO2	287	86-92%

Buckwheat Seed	MSO	174	62-86%

	5-OH-MSO2	174	71-81%

Buckwheat Groats	MSO	75	76-90%

	5-OH-MSO2	75	86-98%

 

Except for radish roots, all of these storage stability data were
acceptable.  The radish root stored recoveries were low, did not well
support the residue results found and might have required an adjustment
of residues by three or four fold.  Incorporating radish roots into the
Root and Tuber Crop Group 1, at a tolerance of 4.0 ppm for the crop
group, as recommended below, obviates any potential need for such an
adjustment.  

860.1400 Water, Fish, and Irrigated Crops

Not Applicable

860.1460 Food Handling

Not applicable

860.1480 Meat, Milk, Poultry, and Eggs

No major feedstuffs are associated with these proposed new uses for
sethoxydim, so data requirements related to meat, poultry milk or eggs
are not relevant to the current action

860.1500 Crop Field Trials

DER Reference List

46417301.der.doc (Buckwheat)

46417301.de2.doc (Buckwheat processing)

46417302.der.doc  (Okra)

46417303.der,doc (Borage)

46417304.der.doc (Dillweed)

46417304,de2.doc (dill processing)

46417305.der.doc (radish)

Table 5.  Summary of Residues from the Crop Field Trials with
Sethoxydim.

Crop Matrix	Applic. Rate

(lb ai/A)	PHI (days)	Residues (ppm)

	Mean	Std. Dev.	HAFT 	Min.	Max.

Buckwheat (proposed use =  1 lb ai/A total application rate, 21-day PHI)

Seed	0.98 – 1.00	19 - 23	8.77	2.77	12.24	3.78	13.74

Okra (proposed use = 1.1 lb ai/A total application rate, 14-day PHI)

Okra Pods	1.09 – 1.14	13-14	0.687	0.337	1.23	0.28	1.32

Borage (proposed use = 1 lb ai/A total application rate, 23-day PHI)

Seed	1.0	27	2.76	0.72	2.9	1.8	3.5

Dillweed (proposed use = 1 lb ai/A total application rate, 14-day PHI)

Leaves and Stems	0.99 - 1.02	13 - 14	5.20  	1.23	6.4	3.4	6.9

Dried Leaves and Stems	0.99 - 1.02	13 - 14	3.08  	1.29	4.15	1.36	4.71

Radish (proposed use = 0.5 lb ai/A total application rate, 14-day PHI)

Top	0.49 - 0.51	13-15	1.35	0.977	3.2	<0.14	3.6

Root	0.49 - 0.51	13-15	0.49	0.200	0.64	<0.09	0.69

SPECIFIC CROPS 

46417301 (buckwheat):

  

IR-4 has submitted field trial studies and a processing study (to
groats) in response to requests from Minnesota, North Dakota and
Washington for registration of sethoxydim for use on buckwheat. 
Proposed label directions for use state that sethoxydim should be
applied at up to 2.5 pints of product per acre per application (0.5 lb
sethoxydim per acre) as a foliar spray.  Do not apply more than a total
of 5.0 pints of product per acre per season (1.0 lb sethoxydim per acre
per season).  Use a minimum of 10 gallons of water per acre.  Sethoxydim
may be applied in ground, aerial, band or spot applications.  Make
applications to growing weeds.  The most effective control will result
from post-emergent applications when weeds are small.  Do not apply at
less than 12-day intervals.  Do not apply more than 2 applications per
season.  The restricted re-entry interval is 12 hours. The preharvest
interval is 21 days.

Adequately representative field trials were conducted in Aurora, SD (2),
Ithaca, NY (1), Hettinger, ND (1), and Brooking, SD (1).  At each site 2
applications of POAST® were made at 0.5 lbs ai/A each, with PHIs of 19
– 22 days.  The maximum total sethoxydim found was 13.74 ppm. 
Residues did not concentrate in groats.  A tolerance of 20 ppm in
buckwheat seed was proposed in the submission.  Using the tolerance
harmonization spreadsheet these data support a recommended tolerance of
19 ppm on the seed. 

Table 6.  Residues for the tolerance spreadsheet

Matrix	DME (ppm)	DME-OH (ppm)	Combined

Residues

(ppm)

Buckwheat Seed	6.7, 3.6

6.8, 8.4

9.0, 11

5.8, 7.3

10, 13

8.0	0.85, 0.18

0.48, 0.88

0.82, 0.98

0.38, 0.36

0.74, 0.74

0.40	7.55, 3.78

7.28, 9.28

9.82, 11.98

6.18, 7.66

10.74, 13.74

8.40

 

 

46417302 (okra):  

IR-4 has submitted field trial studies in response to requests from
South Carolina, Florida, Louisiana, Oklahoma, Arkansas, Arizona, North
Carolina, Georgia, and Tennessee for registration of sethoxydim for use
on okra.  Proposed label directions for use state that sethoxydim should
be applied in up to two applications at up to 1.5 pints of product per
acre per application (0.3 lb sethoxydim per acre) as a foliar spray; to
be followed by one application at 2.5 pints of product per acre (0.5 lb
sethoxydim/acre).  Do not apply more than a total of 5.5 pints of
product per acre per season (1.1 lb sethoxydim per acre per season). 
Use a minimum of 10 gallons of water per acre.  Sethoxydim may be
applied in ground, aerial, band or spot application. Make applications
to growing weeds.  The most effective control will result from
post-emergent applications when weeds are small.  Do not apply at less
than 12-day intervals.  Do not apply more than 3 applications per
season.  The restricted re-entry interval is 12 hours.  The preharvest
interval is 14 days. 

 

Adequately representative field trials were conducted in Clinton, NC (1
trial), Weslaco, TX (2 triuals), Tifton, GA (1 trial), Gainesville, FL
(1 trial), and Crossville, TN (1 trial).  At each site 3 applications of
POAST® were made, yielding a total seasonal rate of 1.1 lbs
ai/A/season, with PHIs of 13 – 14 days.  The maximum total sethoxydim
residue found was 1.32 ppm.  A proposed tolerance was 4.0 ppm. 
According to the Tolerance Harmonization Spreadsheet the data support a
tolerance of 2.5 ppm.  

Table 7.  Residues for tolerance spreadsheet

Matrix	DME (ppm)	DME-OH (ppm)	Combined

Residues

(ppm)

Okra Pods	0.86, 0.98

0.17, 0.30

0.47, 0.62

0.50, 0.44

0.55, 0.53

0.18, 0.20	0.28, 0.34

0.11, 0.16

0.26, 0.31

0.18, 0.17

0.24, 0.23

0.084, 0.084	1.14, 1.32

0.28, 0.46

0.73, 0.93

0.68, 0.61

0.79, 0.76

0.264, 0.284

 

 

46417303 (borage):   

IR-4 has submitted field trial studies in response to a request from
North Dakota for registration of sethoxydim for use on borage.  Proposed
label directions state that up to two applications should be made at up
to 2.5 pints of product per acre per application (0.5 lb sethoxydim per
acre) as a foliar spray.  Do not apply more than a total of 5.0 pints of
product per acre per season (1.0 lb sethoxydim per acre per season). 
Use a minimum of 10 gallons of water per acre.  Sethoxydim may be
applied via ground, aerial, band or spot application.  Make applications
to growing weeds.  The most effective control will result from
post-emergent applications when weeds are small.  Do not apply at less
than 12-day intervals.  Do not apply more than 2 applications per
season.  The restricted entry interval is 12 hours.  The preharvest
interval is 23 days.  

Adequately representative field trials were conducted in Carrington, ND
(1 trial) and Fargo, ND (1 trial).  At each site 2 applications were
made of 0.5 lbs ai/A each, with PHIs of 23 – 27 days.  The maximum
total sethoxydim found was 3.49 ppm.  The season was reported to be
wetter than normal and heavy rains after cutting the borage delayed the
harvest.  Borage shatters easily and this rain adversely affected the
amount of seed that could be collected.  The unusually large amounts of
rain may have caused residues to deviate significantly from what would
normally be found.  This may be especially of concern for rain that fell
after cutting and before harvesting, while the crop lay in the fields. 
But on the one hand, crop was left in the field at one site, Carrington,
for a whole month between cutting and harvesting; while on the other
hand the Carrington crop had residues that were comparable to those at
the Fargo site, which was not left in the field longer than normal. 
Thus the rainy conditions (and limited number of trials) introduced some
uncertainty about the results, and better records of actual rainfall
might have allowed a closer interpretation, but in a deviation from GLP,
such records were not kept.  

Based upon these field trial data, IR-4 has proposed a tolerance of 5.0
ppm for the borage seed.  Using the tolerance harmonization spreadsheet
HED instead calculates a recommended tolerance of 6.0 ppm for borage
seed.

Table 8. Residues for the tolerance spreadsheet

Matrix	DME (ppm)*	DME-OH* (ppm)	Combined

Residues

(ppm)

Borage Seed	3.2, 1.6

2.4, 2.5	0.29, 0.17

0.40, 0.46	3.49, 1.77

2.80, 2.96

	

 

 

46417304 (dill):    

IR-4 has submitted field trial studies and a processing study (to dried
dillweed and to dill oil) in response to a request to control annual and
perennial grasses in dillweed.  Proposed label directions state that up
to applications per year of up to 2.5 pints of POAST® each should be
made per acre (0.5 lb active sethoxydim per acre) as a foliar spray.  Do
not apply more than a total of 5.0 pints of product per acre per season
(1.0 lb active sethoxydim per acre per season).  Use a minimum of 10
gallons of water per acre.  Sethoxydim may be applied in ground, aerial,
band or spot application.  Make applications to growing weeds.  The most
effective control will result from post-emergent applications when weeds
are small.  Do not apply at less than 14-day intervals.  Do not apply
more than 2 applications per season.  The restricted entry interval is
12 hours.  The preharvest interval is 14 days.

Three field trials were conducted near Prosser, WA.  At each site 2
applications were made of 0.5 lbs ai/A each, at 14 day intervals, with
PHIs of 13 – 14 days.  The maximum total sethoxydim found in fresh
dillweed leaves was 6.9 ppm.  Maximum residues in dried dillweed leaves
were 4.71 ppm.  Residues did not concentrate in dill oil.  Data support
a tolerance of 10 ppm in/on fresh dillweed. These field trials are
adequately representative.

Table 9  Residues for tolerance spreadsheet

Matrix	DME (ppm)	DME-OH (ppm)	Combined

Residues

(ppm)

Dillweed, Fresh Leaves

	4.2, 3.2

5.2, 4.4

4.2, 2.4

	1.3, 1.1

1.7, 1.5

1.0, 1.0

	5.5, 4.3

6.9, 5.9

5.2, 3.4

Dillweed, Dried Leaves (Spreadsheet not used)	1.7, 1.2

4.0, 3.0

3.5, 2.2

	0.27, 0.16

0.71, 0.58

0.62, 0.51

	1.97, 1.36

4.71, 3.58

4.12, 2.71

 

 

46417305  (Radish): 

IR-4 has submitted field trial studies in response to a request for use
on radish for control of annual and perennial grasses.  Proposed label
directions state that applications of up to 2.5 pints of POAST® should
be made per acre per application (0.5 lb active sethoxydim per acre) as
a foliar spray.  Do not apply more than a total of 2.5 pints of product
per acre per season (0.5 lb active sethoxydim per acre per season).  Use
a minimum of 10 gallons of water per acre.  May be applied in ground,
aerial, band or spot application.  Make applications to growing weeds. 
The most effective control will result from post-emergent applications
when weeds are small.  Do not apply at less than 12-day intervals.  Do
not apply more than 1 application per season.  The restricted entry
interval is 12 hours.  The preharvest interval is 14 days.  

Adequately representative field trials were conducted in Freeville, NY
(1 trial), Gainesville, FL (2 trials), Willard, OH (1 trial), East
Lansing, MI (1 trial), and Salinas, CA (1 trial).  At each site 1
application was made of 0.5 lbs ai/A, with a PHI of 14 days.  The
maximum total sethoxydim found in radish tops was 3.6 ppm and in radish
roots was 0.69 ppm.  The data on radish tops were supported by
concurrent stability data, but in the concurrent stability study on
roots, residues depleted to recoveries as low as 48% for DME (average
56%) and 20% for DME-OH (average 20%).  Combining and pro-rating the
effects of 48% stability for DME and 20% DME-OH, total sethoxydim
residues may be depleted to as low as 28% - 30% of the actual value. 
Thus, the maximum value on radish roots might be corrected from 0.69 ppm
to as high as 2.5 ppm.

A tolerance was proposed by IR-4 on radish tops at 5.0 ppm.  Using the
tolerance harmonization spreadsheet the data support a slightly
different tolerance of 4.5 ppm on the radish tops.  

IR-4 has proposed a crop sub-group tolerance for Root Vegetable (except
sugar beet) subgroup 1B at 4.0 ppm.  Using the tolerance harmonization
spreadsheet, the radish data can support a tolerance of 1.1 ppm on
radish roots if not corrected for analyte stability, or somewhere around
4 ppm if maximally corrected.   As further considerations, other
existing root crop tolerances that would be subsumed under crop
sub-group 1B have been translated from sugar beet and other root and
tuber data.  In field trials, sugar beet residues are all below 1.0 ppm.
 Carrots currently have a tolerance of 1 ppm based upon carrot field
trials.  There is currently a tolerance of 4.0 ppm on the tuberous and
corm vegetable crop sub-group 1C.  

Based upon a discussion in ChemSAC (14 June 2006) HED believes that a
best synthesis of all the residue data available for sethoxydim on root
crops and on tuber crops is to set a tolerance at 4.0 ppm for the full
Root and Tuber Vegetables Crop Group 1.   Adequate residue data exists
on a variety of roots and tubers to support such a crop group.  An
existing tolerance on crop sub-group 1C at 4.0 ppm, and an existing
tolerance on horseradish at 4.0 ppm, and a predicted corrected radish
root tolerance to approximately 4.0 ppm, based upon uncertainty in the
radish root database due to poor stability data, combined, can all
support a crop group 1 tolerance at 4.0 ppm. 

Table 10.  Residues for Tolerance spreadsheet

Matrix	DME (ppm)	DME-OH (ppm)	Combined

Residues

(ppm)

Radish Tops

	0.92, 0.99	0.28, 0.33	1.20, 1.32

	3.2, 2.4	0.42, 0.39	3.62, 2.79

	1.2, 1.0	0.28, 0.30	1.48, 1.30

	0.60, 0.69	0.30, 0.30	0.90, 0.99

	0.13, 0.092	<0.052, <0.052	0.18, 0.14

	0.83, 0.78	0.34, 0.28	1.17, 1.06

Radish Roots (Spread-sheet not used)

	0.26, 0.30	0.13, 0.17	0.39, 0.47

	0.40, 0.50	0.19, 0.19	0.59, 0.69

	0.40, 0.40	0.16, 0.16	0.56, 0.56

	0.42, 0.38	0.21, 0.21	0.63, 0.59

	<0.047, <0.047	<0.044, <0.044	0.09, 0.09

	0.40, 0.38	0.20, 0.20	0.60, 0.58

 

 

PP # 0E6204 (Turnip Greens):  

USDA’s IR-4 has submitted a petition for a tolerance on Turnip Greens
in a document entitled Sethoxydim: Magnitude of Residues in/on Turnip
Greens Translated from Surrogate Data.  This is a 45 page document
written by Michael Braverman, and is cited as PR#06289, New Jersey
Agriculture experiment station Publication Mo. 27200-34-00.  There are
several cultivars of turnips grown for various uses of either roots or
greens.  This document addresses only applications of sethoxydim to
turnips grown solely for their greens as human food.  The document
proposes to translate pre-existing field trial data on Brassica to
turnip greens.  As the document explains, turnips are a variety of
Brassica, and EPA is in fact currently considering moving this
particular cultivar of turnips to the Brassica crop group. 
Specifically, although turnip greens are currently a part of crop group
2, as stated above, ChemSAC has approved the proposal to move turnip
greens to group 5, Brassica leafy vegetables (Schneider, Commodity
Reviewer’s Guide 6/12/04).  

The current tolerance on the Brassica crop group is 5 ppm after a
maximum of 2 foliar broadcast applications of POAST® at 1.5 pints/A
each, or 3 pints ai/A/season (sethoxydim at 0.28 lbs ai/A, 0.56 lbs
ai/A/season) with a 30 day PHI.  The proposed use on turnip greens is a
maximum of one application at 1.5 pints/A, for a total of 1.5
pints/A/yr, with a 30 day PHI.  This is equivalent to 0.28 lbs
ai/A/season.  Thus, the total proposed seasonal application of
sethoxydim to turnip greens is half that used on mustard greens,
broccoli and cabbage, and residues therefore are unlikely to exceed the
tolerance (5 ppm) placed on Brassica using data for those crops.  

For that reason, HED concurs that it is reasonable to translate Brassica
residue data to turnip greens and recommends a tolerance for sethoxydim
in/on turnip greens at 5 ppm.  

CONCLUSIONS:  

These studies well reflect the proposed use patterns.  The tolerances
recommended in Table 11 are supported by the available residue data.  

The storage stability studies support the residue data, except for the
radish root data.  However, it should be noted that comprehensive
storage stability studies were not performed with any of these
commodities.  Residue stability recoveries were measured only at the
start and finish of the studies.  If all residues had been stable
throughout the duration of the studies this would not have been a
problem, but because residue stability recoveries at the end of the
radish study were low and variable on radish roots, this deficiency
interfered with the ability to draw appropriate conclusions about the
validity of results in roots from the radish field trials.  

The analytical methods have been deemed adequate for data gathering
analysis of the residues of concern and do address the appropriate
residues of concern.  However, exact descriptions of modifications to
Method 30 for each crop/commodity were not clear; some method recoveries
were outside of acceptable recovery limits; and the method calibration
curves were not linear.  

There was also a deficiency in the borage trials.  In this work there
was an unusually large amount of rain that, at one of two sites delayed
the time crops stayed in the field between cutting and harvest, and
might have affected borage residues in other ways as well; but good
records of the rainfall were not kept.  Lack of good rainfall records
contributed to difficulties in interpreting the effects of weather upon
the borage residues.  

860.1520 Processed Food and Feed

DER Reference List

46417301.der.doc (buckwheat processing)

46417304.der.doc (dill processing)

46417303.der,doc (borage)

Buckwheat

USDA’s Interregional Research Project No. 4 (IR-4) has submitted field
trial data for sethoxydim on buckwheat.  A study of the further
processing of the buckwheat seed into groats was included in this
submission.  In these trials, POAST®, [Sethoxydim, 1.53 % a.i., EC
formulation] was applied to buckwheat in two applications of 0.5 lbs
ai/A, for a total of 1 lb ai/A/yr.  The formulation is made up in water
to yield a 10-40 gal/A foliar spray that includes a crop oil concentrate
at a rate of 2 pints/A.  There was a 14 day interval (RTI) between
applications and a 21 day preharvest interval.  The Buckwheat seed
samples were harvested and a portion was processed into buckwheat groats
using a process that approximated commercial groats production.  The
processed product of importance for buckwheat listed in Table 1 is
buckwheat flour, not groats.  Because this study looked at processing
into groats, that commodity will have to serve as a surrogate for the
flour.  

The method used was entitled “Residue analysis of BASF 9052H
(sethoxydim) and its metabolites by GC/FPD sulfur detector, version 28A.
 This method is a modification of BASF Analytical Method 30
“Determination of BASF 9052H and its Metabolite Residues in Soybean
Seed, Soybean Seed Process Fractions, Chicken Tissue, Beef Tissues, Milk
and Eggs, with modifications 30B, 30G, and 30H, BASF Corporation,
1982-1985.”  Method 30 is published in PAM II for determination of
sethoxydim.   

In this method, residues are extracted with water/methanol in various
ratios, and the extract is crudely cleaned up with alkaline
precipitation and partitioning.  Then the residues are oxidized with
peroxide to the two compounds 3-[2-(ethylsulfonyl) propyl]-pentanedioic
acid and 3-[2-(ethylsulfonylpropyl]-3 hydroxy-pentanedioic acid (MSO and
3-OH-MSO2) and further cleaned up through a silica gel column. 
Additional cleanup may be done by HPLC.  MSO and 3-OH-MSO2 are then
derivatized to the dimethyl esters: 3-[2-(ethylsulfonyl)
propyl]-pentanedioic acid dimethyl ester and 3-[2-(ethylsulfonyl)
propyl]-3-hydroxy-pentanedioic acid dimethyl ester (DME and DME-OH); and
the esters are subsequently determined by GC/FPD in the sulfur mode.  
This method has been shown to detect the analytes down to 0.05 ppm each
in all matrices tested.  

 

Method 28A had a lower limit of method validation at 0.042 ppm in both
seed and groats.  Recoveries of DME were tested at 0.042 – 15 ppm and
ranged from 33% - 114% in seed and from 71% - 121% in groats. 
Recoveries of DME-OH were tested at 0.042 – 15 ppm and ranged from 57%
- 138% in seed and from 71% - 138% in groats. Although recoveries were
not acceptable for DME or DME-OH over part of the range of recoveries,
overall the recoveries may be considered adequate for these trials and
the field trial data can stand.  The standard curve was not linear but
was fitted with a quadratic equation.  The method is acceptable as a
data-gathering method for sethoxydim on buckwheat seed and groats.  

In a concurrent study, residues were shown to be stable for the duration
of the study.   

Adequate storage stability has been demonstrated to support this study. 
 

A comparison of the residues in the RAC (0.69 ppm) with those in groats
(0.84 ppm) resulted in a concentration factor of 1.22, i.e., some
concentration was observed.  However, let it be noted that at the front
end of the groats processing the buckwheat was dried to 13.5% moisture. 
There is no indication of the moisture content of the original seed. 
USDA’s National Nutrient Database for Standard Reference – Release
18 (http://www.ars.usda.gov/Services/docs.htm?docid=8964) provides
reference values for the major nutrient composition of foods.  This
reference database supply’s representative values for moisture in
buckwheat at 9.8%, buckwheat flour at 11.2% and buckwheat groats at
8.4%.  [Note that while some of USDA’s composition values are well
documented, some rely on a very small sample.  The sample size for
proximate composition of buckwheat commodities range from n= 2 to 6.] 
It is clear that the entire factor of 1.22 could be due to changes in
moisture content alone but there is sufficient uncertainty in moisture
content to occlude knowledge of how well the factor for groats
represents flour.  HED therefore concludes that the factor of 1.22 from
the groats study should be applied to a create buckwheat flour
tolerance.  The groats data are the best information available, and at
least these data stand an index of our uncertainty about the actual
effects of processing.  On that basis, and being slightly liberal, HED
recommends a tolerance of 25 PPM on buckwheat flour. 

Dill

USDA’s Interregional Research Project No. 4 (IR-4) has submitted field
trial data for sethoxydim on dill.  Three field trials were conducted in
the year 2000, in the United States, all in Region 11.

At each test location there were two broadcast foliar applications of
0.5 lbs ai/A each, for a seasonal total of 1 lb ai/A, with a 14 day RTI,
and a 14 day PHI.  An adjuvant of crop oil concentrate was added to the
spray mixture to be applied for all applications at 2 pints/A.  

Residues were determined on fresh dillweed, dried dillweed, and oil. 
The method used was entitled “Residue analysis of BASF 9052H
(sethoxydim) and its metabolites by GC/FPD sulfur detector, version 16A
(fresh and dry) and 16b (dill oil),” modifications of BASF Analytical
Method 30. [PAM II for determination of sethoxydim].   Briefly, residues
are extracted with water/methanol in various ratios and subjected to
crude clean-up steps.   The residues are oxidized with peroxide to the
two compounds 3-[2-(ethylsulfonyl)propyl]-pentanedioic acid and
3-[2-(ethylsulfonylpropyl]-3 hydroxy-pentanedioic acid (MSO and
5-OH-MSO2) and further cleaned through a silica gel column eluted
acetone/hexane and acetone/methanol/hexane.  Additional cleanup may be
done by HPLC on a silica column.  MSO and53-OH-MSO2 are then derivatized
to the dimethyl esters: 3-[2-(ethylsulfonyl)propyl]-pentanedioic acid
dimethyl ester and 3-[2-(ethylsulfonyl)propyl]-3-hydroxy-pentanedioic
acid dimethyl ester (DME and DME-OH); and the esters are subsequently
determined by GC/FPD in the sulfur mode.   This method has been shown to
detect the analytes down to 0.05 ppm each in all matrices tested.  

Method 16A had a lower limit of method validation at 0.085 ppm DME and
DME-OH.  Recoveries were acceptable at all concentrations.  The standard
curve was not linear and instead was fit with a quadratic equation. The
method is acceptable as a data-gathering method for sethoxydim on fresh
and dried dill.  

Method 16B had lower limits of method validation at 0.083 DME and 0.085
ppm DME-OH.  The standard curve was not linear and instead was fit with
a quadratic equation. The method is acceptable as a data-gathering
method for sethoxydim in dill oil.  

A concurrent stability study showed that residues of sethoxydim were
adequately stable to support this study.  

A comparison of the residues in fresh dill with those in dried dill and
dill oil showed no concentration.  Residues in dried dillweed were 0.8
those in fresh dillweed and those in dill oil were 0.02 those on fresh
dillweed.

Borage

Borage is often grown as an oilseed from which borage oil may be
extracted, leaving a borage press cake, or meal.  Although a borage oil
processing study was intended to be performed, heavy rains between
cutting and harvest of borage caused shattering, and insufficient seed
could be collected to perform the processing study.  For that reason,
IR-4 has proposed translating residues in borage meal and oil from
canola meal.  

For background, in a previous canola processing study, residues in
canola seed were 116 ppm, those in the meal were 131 ppm, those in the
crude oil were 76 ppm, and in the refined oil were 3.1 ppm.  Thus,
residues in the canola meal were slightly concentrated relative to the
seed, by a factor of 1.13, while residues in the pressed canola oil were
less than those in the seed, by a factor of 0.66 for the crude oil and
0.03 for the refined oil.  Based on this study, and field trials treated
at the regular rate showing maximum residues in canola seed of 35 ppm, a
tolerance of 35 ppm currently exists for canola, with a tolerance of 40
ppm for canola meal, and no tolerance has been promulgated for canola
oil.  

To be very conservative, IR-4 has proposed the application of the 40 ppm
tolerance from canola meal to both borage meal and borage oil (based
upon a tolerance for residues in canola seed of 35 ppm).  HED calculates
that a borage meal tolerance can be based upon the canola concentration
factor of 1.13 X the recommended borage seed tolerance of 6.0 ppm; but
because of uncertainties in this translation, and to be appropriately
conservative, HED proposes a tolerance in borage meal of 10 ppm.  

HED recommends that a tolerance is not needed in borage oil.  This
recommendation is based upon the lack of concentration of residues in
canola oil and is backed up by no concentration of sethoxydim residues
in the extracted oils of any of several other oil crops.  HED therefore
recommends using the seed tolerance of 6.0 ppm to cover borage oil.  

Table 11.  Processing Factors

Crop	Commodity	Residues in RAC (ppm)	Residues in Processed Commodity
(ppm) 	Concentration Factor	Does the residue concentrate?

Buckwheat	Groats	6.9	8.4	1.22	Yes, slightly

Dillweed	Dried Dillweed	4.30	3.42	0.80	No

	Dill Oil	4.30	0.091	0.02	No

Borage	Borage Oil	2.76	Not determined	Translated from canola, 0.03 for
refined canola, 0.66 for crude canola1	No

	Borage meal	2.76	Not determined	1.13 translated from canola1	Yes,
slightly

1.  Insufficient sample was harvested to determine borage concentration
factors directly.  In lieu of a borage processing study, processing
factors were translated from canola.  

CONCLUSIONS:  

The field trials were all performed at normal application rates and so
do not support the waiving of processing studies for any of the
commodities currently under consideration.  The processing residue data
are supported by the storage stability studies; and the analytical
methods are adequate for the analysis of the residues of concern.  The
processing residue data do address the appropriate residues of concern. 
The buckwheat was processed into groats, not flour as required by Table
1, however HED concludes that the resulting buckwheat groats processing
factor provides an adequate index of the uncertainty in estimating these
residues and the study may be used to estimate a tolerance in buckwheat
flour.  

860.1850 and 860.1900 Confined and Field Accumulation in Rotational
Crops

The available confined rotational crop data were determined to be of
limited value in determining the need for rotational crop tolerances
because no data concerning the nature of the residues in rotational
crops were reported.  Based on an acceptable limited rotational crop
study, in which residues of sethoxydim were below the LOQ in all
rotational crops at all plantback intervals, HED concluded that no
tolerances are required for rotational crops provided plantback
intervals are greater than 30 days.

860.1550 Proposed Tolerances

The tolerance expression for sethoxydim is for the combined residues of
sethoxydim and its metabolites containing the 2-cyclohexen-1-one moiety,
and expressed as sethoxydim.  Current sethoxydim tolerances are listed
in 40 CFR 180.412.  For the individual RACs, the recommended tolerances
were derived with the aid of the Tolerance/MRL Harmonization
Spreadsheet.  Input residue values are listed under each RAC.  The
existing highest tolerance for some roots and tubers were used for the
Root and Tuber, Crop Group 1 tolerance at 4.0 ppm.  The turnip tolerance
was translated from the Brassica tolerance, and tolerances for processed
RACs were estimated based upon processing information.  The borage
processed products were estimated from the RAC tolerance using canola
processing information.

Table 12.  Tolerance Summary for Sethoxydim

Commodity	Established/Proposed Tolerance (ppm)	Recommended Tolerance
(ppm)	Comments (correct commodity definition)

Buckwheat, grain	20	19	From Tolerance Harmonization Spreadsheet

Buckwheat, flour	20	25	From a processing factor of 1.22 applied to the
buckwheat tolerance and raised to 25 ppm because of uncertainties in the
result.  

Okra	4.0	2.5	From Tolerance Harmonization Spreadsheet

Borage, seed	5.0	6.0	From Tolerance Harmonization Spreadsheet

Borage, meal	40	10.0	From seed, with correction for a small
concentration factor from canola, and uncertainty

Borage, Oil	40	None	No separate tolerance is required because the oil is
covered by the seed tolerance.  

Dillweed, Fresh leaves	10	10	From Tolerance Harmonization Spreadsheet

Dillweed, Dried leaves	10	None	No separate tolerance is required because
the dried dillweed is covered by the fresh dillweed tolerance.  

Radish, Tops	5.0	4.5	From Tolerance Harmonization Spreadsheet

Turnip, Greens	5.0	5.0	Translated from Brassica

Root and Tuber Vegetable, Crop group 1	4.0	4.0	Incorporate both radish
root, and existing tolerances for carrot (currently 1.0 ppm);
horseradish (currently 4.0 ppm); beet, garden (currently 1.0 ppm); beet,
sugar, root (currently 1.0 ppm); and tuberous and corm vegetable
subgroup 1D (currently 4.0 ppm)

Codex/International Harmonization

There are no Codex maximum residue limits (MRLs) for sethoxydim.  

There are Canadian MRLs based on the cyclohexen-1-one moiety calculated
as sethoxydim for the root and tuber crops: carrot, turnip and potato,
at 0.1, 0.2, and 4.0 ppm, respectively.  There is also a Mexican MRL
based on parent sethoxydim (only) on potato at 4 ppm.  The Canadian
tolerances on carrot and turnip are well below those needed to cover
these residues in the U.S., while the 4.0 ppm potato tolerance is the
same as the U.S. tolerance. Many Mexican MRLs are based upon U.S.
tolerances, but expressed as parent only, as Mexico appears to have done
for sethoxydim on potato.

There are Canadian MRLs based on the cyclohexen-1-one moiety calculated
as sethoxydim for the Brassica crops: cabbage and broccoli at 2.0 ppm
and 0.5 ppm, respectively.  There are also Mexican MRLs based on parent
sethoxydim (only) on broccoli, cabbage, cauliflower and Brussels sprout,
all at 5 ppm.  The Canadian tolerances on cabbage and broccoli are well
below those needed to cover these Brassica residues in the U.S.  As
Mexico appears to have done for these four Brassica crops, many Mexican
MRLs are based upon U.S. tolerances, but expressed as parent only.  

Template Version September 2005



INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name:

(±)-(EZ)-2-(1-ethoxyiminobutyl)-5-[2-(ethylthio)propyl]-3-hydroxycycloh
ex-2-enone	Common Name:

‮√  Proposed tolerance

‮  Reevaluated tolerance

  Other	Date:  4 August 2006

Codex Status (Maximum Residue Limit)	U. S. Tolerance

 √  No Codex proposal step 6 or above

‮  No Codex proposal step 6 or above for      commodities requested
Petition numbers: PP #4E6885 and 0E6204

DP Barcode: 327825 and 327826

Residue definition:  N/A	Reviewer/Branch:  David Soderberg/RRB3

	Residue definition: Sethoxydim and its 2-cyclohexen-1-one containing
metabolites 

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4

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Ÿ

/

/

/

/

/

/

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@

@

@

@

@

@

@

@

愀Ĥ

愀Ĥ

愀Ĥ

‮  No limits

‮  No limits for commodities requested	‮  No limits

‮  No limits for commodities requested

Residue definition:

(±)-2-[1-(ethoxyimino)butyl]-5-[2-

(ethylthio) propyl]-3-hydroxy-2-cyclohexen-1-

one and metabolites containing the cyclohexen-2-one moiety expressed as
sethoxydim

	Residue definition:

Setoxidim

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

Cabbage	2	Broccoli	5

Broccoli	0.5	Cauliflower	5

Carrots	0.1	Cabbage	5

Turnips	0.2	Brussels sprouts	5

Potatoes	4.	Potato	4

Notes:  S. Funk, Jul 22, 2006

 PAGE   

 PAGE   21  of   NUMPAGES  27 

Sethoxydim              Summary of Analytical Chemistry and Residue Data
Barcodes:  327825 and 327826