                                       	
                    UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                               WASHINGTON, D.C.  20460
                                       
	OFFICE OF CHEMICAL SAFETY
	AND POLLUTION PREVENTION
                                                                               


MEMORANDUM

Date:  March 6, 2014

SUBJECT:	Clomazone.  PP#2E8136.  Brassica, Head and Stem, Subgroup 5A; Rhubarb; and Pea, Southern.  Summary of Analytical Methods and Residue Data.

PC Code:  125401
DP Barcodes:  D410436
Decision Nos:  473594
Registration No.:  279-3052
Petition Nos.:  2E8136
Regulatory Action:  Section 3 Registration
Risk Assessment Type: Res Chem
Case No.:  7203
TXR No.:  NA
CAS No.:  81777-89-1
MRID No.:  49026901, 49026902, 49026903
40 CFR:  180.425
	

FROM:	Susan V. Hummel, Chemist & Senior Scientist
		Risk Assessment Branch 4
		Health Effects Division (7509P)
		
THROUGH:	Thurston Morton, Chemist
		Risk Assessment Branch 4
		Health Effects Division (7509P)

TO:		Kable Davis, PM25
		Herbicide Fungicide Branch, Registration Division (7505P)
		

MRID Summary Table
MRID No.
Study Type
Comments
49026901
49026902
49026903
860.1500 Brassica, head and stem, subgroup 5A
860.1500 Rhubarb
860.1500 Pea, southern
New DER; 49026901.der.docx
New DER; 49026902.der.docx
New DER; 49026903.der.docx

The Interregional Research Project Number 4 (IR-4) has submitted a petition to establish tolerances for residues of clomazone on Brassica, head and stem, subgroup 5A; rhubarb; and pea, southern.  In connection with the petition, IR-4 requests amended registration of the FMC  product Command Technical (EPA Reg. No. 279-3052), to allow use on Brassica, head and stem, subgroup 5A; rhubarb; and pea, southern.  Tolerances for residues of clomazone, per se, have been established on a number of commodities ranging from 0.02 ppm in rice grain to 0.1 ppm in cabbage and several squashes in 40 CFR §180.425.
Executive Summary

Clomazone is an herbicide which is registered for use on snap beans, succulent peas, cabbage, cotton, cucurbits, pepper, mint, rice, soybeans, sugarcane, and tuberous & corm vegetables (except potato).  Tolerances for clomazone on these commodities are published in 40 CFR 180.425, including cabbage at 0.1 ppm.  Clomazone products are formulated as emulsifiable concentrates and microencapsulated formulations.  Applications are usually made as a single or split (2) pre-plant, or early post-emergence broadcast applications.  The current application requests adding Brassica, head and stem, subgroup 5A; rhubarb; and pea, Southern; to the label for Command 3ME, and proposes tolerances follows.
	Brassica, stem and head subgroup 5A	0.1 ppm
      Rhubarb					0.3 ppm
      Pea, Southern, succulent seed			0.05 ppm
      Pea, Southern, dry seed			0.05 ppm
      Pea, Southern, hay				0.05 ppm
And at the same time, revoke the tolerance for cabbage at 0.1 ppm, since cabbage will be covered by the new tolerance for Brassica, head and stem, subgroup 5A.

The residue of concern is clomazone, per se.  Residues of clomazone following treatment at the proposed rates to broccoli and southern pea, are non-quantifiable in broccoli, and southern pea seed (succulent and dry) and southern pea hay.  Residues of clomazone following treatment at the proposed rates to rhubarb resulted in quantifiable residues of up to 0.062 ppm; a 0.15 ppm tolerance is recommended.
	
Regulatory Recommendations and Residue Chemistry Deficiencies

HED recommends for the proposed tolerance, with corrections specified below, and for the associated amended use.  The current tolerance expression is in accord with our current guidance on tolerance expressions.  The field trials for clomazone on broccoli, rhubarb, and southern peas are adequate.  The enforcement analytical method is adequate. The residue data are supported by available storage stability data.  

Tolerance Summary for Clomazone.  § 180.425
Commodity
                       Current/Proposed Tolerance (ppm)
                          Recommended Tolerance (ppm)
Comments; Correct Commodity Definition
Brassica, stem and head subgroup 5A
                                      0.1
                                     0.10
Brassica, head and stem, subgroup 5A. Tolerance changed to add a significant figure.
Rhubarb
                                      0.3
                                     0.30
Tolerance changed to add a significant figure.
Pea, Southern, succulent seed
                                     0.05
                                     0.05

Pea, Southern, dry seed
                                     0.05
                                     0.05

Pea, Southern, hay
                                     0.05
                                     0.05
Cowpea, hay and Cowpea, forage.  Southern pea hay is a very minor feed, but cowpea is a type of southern pea.


Revisions to Petitioned-For Tolerances and Existing Tolerances

Revisions are recommended to petitioned-for tolerances for consistent naming of commodities, and to add a significant figure.  The recommended changes are documented in the Table above.  Tolerances are being established for cowpea, forage, and cowpea, hay, rather than southern pea hay, because cowpea is a type of southern pea.

International Harmonization

There are no CODEX MRLs for residues of clomazone on any commodity.  Canada has not established MRLs for the commodities in this petition.

Required Label Changes

No label revisions are required; however, it should be noted that while the proposed maximum use rate on rhubarb is 1 application at 1.5 lb ai/A at dormancy, the submitted field trial data for rhubarb would support a second application at 1.0 lb ai/A a minimum of 50 days after the first application, with a PHI of 42 days, with a maximum seasonal application rate of 2.5 lb ai/A.  If a second application on rhubarb is desired, the petitioner should submit an amended petition to reflect this proposed use

Background

Clomazone is an herbicide which is registered for use on snap beans, succulent peas, cabbage, cotton, cucurbits, pepper, mint, rice, soybeans, sugarcane, and tuberous & corm vegetables (except potato).  Tolerances for clomazone on these commodities are published in 40 CFR 180.425, including rice grain and straw at 0.02 ppm..  Clomazone products are formulated as emulsifiable concentrates and microencapsulated formulations.  Applications are usually made as a single or split (2) pre-plant, or early post-emergence broadcast applications.  A layby use is registered for clomazone on cotton.  The current application requests adding Brassica, head and stem, subgroup 5A, rhubarb, and southern pea to the Command 3ME label.

The chemical structure and nomenclature of the active ingredient, clomazone, are presented below in Table 1.  The physicochemical properties are presented below in Table 2.


TABLE 1.	Test Compound Nomenclature.
Compound
Chemical Structure


Common name
Clomazone
Company experimental name
FMC 57020
IUPAC name
2-(2-chlorobenzyl)-4,4-dimethylisoxazolidin-3-one
CAS name
2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone
CAS #
81777-89-1
End-use product/(EP)
Command ME, EPA Reg. No. 279-3158


TABLE 2.	Physicochemical Properties of the Technical Grade Test Compound: Clomazone.  
Parameter
Value
Reference
Melting point/range
  25 C, broad range
MRID 00144241
pH
  6.89 + 14 (supernatant of slurry)
MRID 00144241
Density
  1.187 g/mL
MRID 00144241
Water solubility ( mg/L at unspecified C)
  1100 mg/L
MRID 00144241
Solvent solubility (mg/L at unspecified C)
  >200 mg/L in Tenneco 500-100
  4.5-5.0 mg/L  in Isopar M
  >90 mg/L in refined soybean oil
  Infinite in dimethyl formamide
  Infinite in cyclohexanone
MRID 00144241
Vapour pressure at 25 C
  1.92 x 10 [-2] Pa (1.44 x 10 [-4] mm Hg)
MRID 00144241
Dissociation constant (pKa)
  N/A neither acidic nor basic
MRID 00144241
Octanol/water partition coefficient Log(KOW)
  350 (log p = 2.54)
MRID 00144241
UV/visible absorption spectrum
  Not available



860.1200  Directions for Use


Table 3.  Summary of Directions for Use of Clomazone
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
Brassica, Head & Stem, Subgroup 5A; Direct Seeded Cabbage; Transplant Broccoli
                                   Broadcast
                                 3.0 lb/gal ME
                                  [279-3158]
                                     0.25
                                       1
                                      NS
                                      NS
Use as a soil applied treatment prior to weed emergence.
                              Transplant Cabbage
                                   Broadcast
                           3.0 lb/gal ME [279-3158]
                                   0.25-0.5
                                       1
                                      NS
                                      NS
Use lower rate on coarse soils and higher rate on fine soils. Use as a soil applied treatment prior to weed emergence.
                                    Rhubarb
                                   Broadcast
                           3.0 lb/gal ME [279-3158]
                                      1.5
                                      NS
                                      NS
                                      NS
Apply to dormant rhubarb prior to leaf emergence.
                                Peas, Southern
                                   Broadcast
                           3.0 lb/gal ME [279-3158]
                                     0.52
                                       1
                                      NS
                                      NS
Use as a soil applied treatment prior to weed emergence.
		

Label restrictions include: 
Command 3ME herbicide may be utilized as a soil applied treatment prior to weed emergence, for suppression or control of annual grass and broadleaf weeds in snap beans (succulent), brassica (head and stem subgroup 5A), cucumbers, peas (southern), peas (succulent), peppers, rhubarb, squash (including processing pumpkins) and sweet potatoes. 

Make a single herbicide application in a minimum of 10 gallons of water per acre at the rate(s) specified in the individual crop listings hereafter. Apply as a pre-emergent soil applied treatment prior to seeding or transplanting, or after seeding but prior to crop emergence. Place seed, or roots of the transplants, below the chemical barrier when planting.

Rotational Crop Restrictions include suggestions for minimizing increased risk to rotational crops plus the following instructions for applications on rice at up to 0.8 lb ai/A
	-    The following crops may be planted anytime:   cabbage (transplants), cotton, peas, peppers, rice, soybeans, squash, sweet potatoes, tobacco, tuberous and corm vegetables. 
	-    The following crops may be planted after 9 months: All crops listed above plus: beans (succulent and dry), cabbage (direct seeded), corn (field, pop, seed, sweet), cotton, cucurbits, peanuts, potatoes, sorghum, sugar beets, tomatoes (transplanted).
	-    The following crops may be planted after 12 months:  All crops listed above plus: tomatoes (direct seeded) and wheat
	-    The following crops may be planted after 16 months:  all crops.


Conclusions.  The label use directions for clomazone on Brassica, head and stem subgroup 5A, transplant broccoli and cabbage; and southern peas are adequate to evaluate the residue field trial data.  The use directions for rhubarb are not clear.  The number of applications per season, and maximum seasonal application rate are not stated.   The submitted field trial data for rhubarb would support a second application at 1.0 lb ai/A a minimum of 50 days after the first application, with a PHI of 42 days, with a maximum seasonal application rate of 2.5 lb ai/A.


OPPTS GLN 860.1300 Nature of the Residue - Plants
Soybeans: PP#4G2987, L. Propst, 4/17/84; PP#4F3128, J. Worthington, 9/24/84
Corn: PP#0G3919, J. Garbus, 11/8/91
Cotton: PP#2F4077, R.W. Cook, 10/28/92
Sweet Potatoes: PP#8E3628, M. J. Nelson, 4/22/92
Tomatoes and Bell Pepper: PP#9E3778, F. D. Griffith, 8/6/90
Alfalfa: PP#8E3608, A. Smith, 3/15/88

Based on metabolism studies on soybeans, corn, cotton, sweet potatoes, tomatoes and bell peppers, and alfalfa, HED concludes that the nature of the residue in plants is adequately understood.  The major metabolite was 2-chlorobenzyl alcohol.  The postulated major route of metabolism of clomazone in plants is hydroxylation of the methylene bridge carbon of clomazone to form the carbinolamide; decomposition of the unstable intermediate, the carbinolamide, to form the isoxazolidinone moiety and 2-chlorobenzaldehyde.  2-chlorobenzaldehyde reduces to the alcohol or is oxidized to the carboxylic acid.  The alcohol, the carboxylic acid, and the isoxazolidinone metabolites form glycosides and/or amino acid conjugates.  Minor pathways include hydroxylation of clomazone to form monohydroxylated and possibly dihydroxylated metabolites.  Based on low levels of these metabolites found in crops, the residue of concern for regulatory and risk assessment purposes in plants is clomazone per se (PP#8E3628, M. J. Nelson, 4/22/92).

The nature of the residue in plants and livestock is adequately understood.  The residue of concern is clomazone per se as specified in 40 CFR 180.425.


OPPTS GLN 860.1300 Nature of the Residue - Livestock
Ruminants: 40070001, PP#4F3128, L. Bradley, 5/11/87, DEB#5505, F. Griffith, 7/26/89
Poultry: 41663304, 41663305, PP#0G3919, J. Garbus, 11/8/91

As there are no livestock feed stuffs currently associated with Brassica, rhubarb, or southern peas, issues pertaining to the nature of the residue in livestock are not germane to this petition.

Goats were fed 0.5 ppm or 5.0 ppm ring-labeled clomazone by capsule (MRID 40070001) .  Morning and evening milk samples were pooled by day.  The majority (86-93%) of the residue was eliminated in the urine or feces.  Less than 1% of the residue was found in each of the tissues, and the residues were below detectable levels.  

Poultry were fed 0.5 ppm or 5.0 ppm ring-labeled clomazone in their feed (MRIDs 41663304, 41663305).  Only egg yolk and liver contained significant levels of residues.  Clomazone, per se, was not detected in any tissue.  Unidentified residues polar conjugates, which appeared to be amino acid adducts.  

Ortho-chlorobenzoic acid (OCBA) is a plant metabolite of clomazone which is not a rat metabolite.  OCBA is about 5% of the residue in alfalfa.  The polar residues in plants are postulated to be multiple hydroxylated metabolites.  


OPPTS GLN 860.1340: Analytical Enforcement Methodology
PAM II, Method I

Adequate enforcement methods are available for the determination of the residues of clomazone in plants.  Briefly, samples are acid hydrolyzed, hexane extracted, Na2CO3 washed, and cleaned-up with a Florisil column.  The resulting samples are analyzed by gas chromatography (GC) using a nitrogen phosphorus detector (NPD) or mass spectrometer (MS).  The limit of quantitation (LOQ) for this method is 0.05 ppm.  A confirmatory procedure (GC/MS-SIM) is available (Method I, PAM II).

Clomazone was determined in broccoli using the analytical method adapted from method FMC No. ACG 124.  A number of minor modifications to the method were specified, including the use of an accelerated solvent extractor (ASE) in place of the extraction/partition steps and the use of an MSD detector in place of the nitrogen-phosphorus detector.  Briefly, clomazone residues were extracted from a five-gram sample of broccoli with hexane using an ASE.  The extracts were placed in a freezer for at least 1 hour and then evaporated to dryness.  Residues were redissolved in hexane for GC/MSD analysis, using single ion monitoring (SIM), monitoring m/z 204, for quantitation..  The column used was not specified in the report.  The LOQ (determined as the LLMV) was 0.03 ppm for broccoli and rhubarb; and 0.05 ppm in southern pea commodities.  The calculated LOQ and LOD, respectively, were 0.01850 and 0.006168 ppm in broccoli; 0.0394 and 0.0131 ppm in rhubarb, and .

Conclusions.  An adequate enforcement method is available.  The residue data were gathered with an adequate data collection method.


860.1360 Multiresidue Methods
MRID 42325301, PP#0G3919, J. Garbus, D178768, 9/21/92

Multiresidue methods data are available for clomazone tested through Protocols C, D and E.  Due to the chemical structure of clomazone, Protocols A and B are not applicable.  GC parameters were gathered for clomazone in Protocol C.  Recovery of clomazone through protocol E was partial and variable (7 to 58%).  


860.1380 Storage Stability
49026901.der.docx, 49026902.der.docx, 49026903.der.docx
D242601, M. Perry, 1/29/98; and D272158, D. Vogel, 1/24/01.  

Concurrent storage stability data were included with each field trial report in this submission, although no zero day data were provided.  Storage stability samples were stored under the same conditions as the field trial samples, and residues of clomazone on broccoli, rhubarb, and pea commodities were stable.  Storage stability data also are available for field corn, rice and sugarcane which demonstrate that residues of clomazone are stable for up to 12 months (Memos, 

TABLE 4.	Summary of Storage Conditions.
                                    Matrix
                           Storage Temperature (°C)
                          Actual Storage Duration[1]
                  Limit of Demonstrated Storage Stability[2]
                                   Broccoli 
                            (Flower head and stem)
                             Frozen (at NDSU lab)
                            -28 to -13 (at MSU lab)
                                 323-531 days
                              (10.6-17.5 months)
                                   539 days
                                 (17.7 months)
                               Rhubarb Petioles
                             Frozen (at NDSU lab)
                            -28 to -9 (at MSU lab)
                                 236-276 days
                               (7.8-9.1 months)
                                   278 days
                                 (9.1 months)
Succulent Shelled Pea
                                     ~ -20
                                 860-1015 days
                              (28.3-33.4 months)
                                   1102 days
                                 (36.3 months)
Plants With Pods, Fresh
                                       
                                 871-1027 days
                              (28.7-33.8 months)
                                   1103 days
                                 (36.3 months)
Shelled Dry Pea
                                       
                                 886-1020 days
                              (29.1-33.6 months)
                                   1101 days
                                 (36.2 months)
Plants with Pods, Dry
                                       
                                 858-1014 days
                              (28.2-33.4 months)
                                   1099 days
                                 (36.2 months)


Conclusions.    Storage stability data are adequate to support the submitted field trial data.

860.1400 Water, Fish, and Irrigated Crops

This topic is not pertinent to the current application for amended registration.

The Clomazone 3ME label contains a label restriction, prohibiting use of rice water on rice fields in which concurrent crayfish or catfish farming are included in the cultural practices, and use water of containing Command 3ME residues from rice cultivation to irrigate food or feed crops which are not registered for use with Command 3ME.

Conclusions.  No further information is required.


860.1460 Food Handling

This topic is not pertinent to the current submission.


860.1480 Meat, Milk, Poultry, and Eggs
Garbus, J., 11/8/91; PP#0G3919

No change is needed to the rice tolerance.  So far, no detectable residues have been found in rice commodities.  A ruminant metabolism study is available which demonstrated that 5.0 ppm clomazone in the livestock diet resulted in 2 to 9 ppb in milk, and 0.03 to 0.05 ppm in the liver and kidney tissue (Memo, Joel Garbus, 11/8/91; PP#0G3919).  Since, under the proposed use, clomazone is not detectable in livestock feed/feedstuffs (<0.05 ppm) and it is transferred to meat and milk at a low level, no detectable residues are expected in meat, or milk.   While rice grain is a poultry feedstuff, high clomazone doses in poultry yielded low levels in tissue and eggs, so that no clomazone residues are expected in poultry commodities.  

860.1500 Crop Field Trials
Broccoli: 49026901.der.docx, 
Rhubarb: 49026902.der.docx, 
Southern peas: 49026903.der.docx

IR-4 has submitted field trial data for clomazone on broccoli, rhubarb, and southern peas.  

Broccoli.  Eight field trials were conducted in the United States during the 2002 growing season in the North American Free Trade Agreement (NAFTA) Growing Zones 1 (NY; 1 trial), 6 (TX; 1 trial), 10 (CA; 5 trials), and 12 (OR; 1 trial).  At each trial location, the treated crops received one preplant application of a 3 lb ai/gal microencapsulated (ME) formulation of clomazone (Command(R) 3 ME) at 0.24-0.25 lb ai/A.  Applications were made using ground equipment in spray volumes of 20.0-35.6 gal/A.  Adjuvants were not added to the spray mixture at any of the trial sites.  Samples of broccoli (flower head and stem) were harvested from all trials at a 52- to 120-day preharvest interval (PHI).

Samples were analyzed for residues of clomazone using an adequate gas chromatography method with mass spectrometric detection (GC/MSD), with single ion monitoring (m/z 204), adapted from FMC No. ACG 124, as discussed above under Analytical Methodology.  The samples were stored frozen awaiting analysis, as discussed above under Storage Stability.  

Following one preplant application of the 3 lb ai/gal ME formulation of clomazone at 0.24-0.25 lb ai/A, residues of clomazone in/on broccoli flower head and stem harvested at a 52- to 120-day PHI were all <LOQ (<0.03 ppm).

TABLE 5.  Summary of Residue Data from Broccoli Field Trials with Clomazone.
Commodity
                                    Analyte
                                  Total Rate
                                   (lb ai/A)
                                  PHI (days)
                            Residue Levels (ppm)[1]

                                       
                                       
                                       
                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                  Std.  Dev.
Broccoli
                                   Clomazone
                                   0.24-0.25
                                    52-120
                                       8
                                   <0.03
                                   <0.03
                                   <0.03
                                   <0.03
                                     0.03
                                     0.03
                                      N/A
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.  N/A = Not applicable.  
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.

Brassica, head and stem, subgroup 5A.  There are 2 representative commodities for Brassica, head and stem, subgroup 5A, broccoli or cauliflower, and cabbage.  The broccoli residue data are discussed above.  A tolerance has been established for residues of clomazone on cabbage at 0.1 ppm (PP#4E4311, N. Dodd, D199086, 04/17/95, MRID 43077301).    Command 4EC was applied at 0.5 lb ai/A as a single broadcast application in at least 10 gallons of water per acre, using ground equipment before seeding or transplanting cabbage.  Clomazone is incorporated to a depth of 1 inch or less.  Residues were reported to be non-quantifable at less than 0.1 ppm except in one sample in which interferences were noted, and the limit of quantitation was 0.17 ppm.

Rhubarb.  Four field trials were conducted in the United States during the 2003 growing season in the North American Free Trade Agreement (NAFTA) Growing Zones 5 (MI; 1 trial) and 12 (OR; 3 trials).  At each trial location, the high- and low-rate treated plots, respectively, received two broadcast applications of a 3 lb ai/gal microencapsulated (ME) formulation of clomazone (Command(R) 3 ME) at 1.49-1.66 or 0.96-1.14 lb ai/A for application one and 0.98-1.14 or 0.75-0.85 lb ai/A for application two, for a total seasonal rate of 2.49-2.76 or 1.71-1.99 lb ai/A.  The first application was made to dormant plants followed by a second application to rhubarb approximately 8-24 inches in height.  Applications were made at 44- to 63-day retreatment intervals (RTIs) using ground equipment in spray volumes of 19.6-45.7 gal/A.  Adjuvants were not added to the spray mixture at any of the trial sites.  Samples of rhubarb were harvested from all trials at a 41- to 44-day preharvest interval (PHI).

Samples were analyzed for residues of clomazone using an adequate gas chromatography method with mass spectrometric detection (GC/MSD), with single ion monitoring (m/z 204), adapted from FMC No. ACG 124, as discussed above under Analytical methodology.  The samples were stored frozen awaiting analysis, as discussed above under Storage Stability.  

Following two foliar broadcast applications of the 3 lb ai/gal ME formulation of clomazone at 2.49-2.76 (~1.7  -  1.8x) and 1.71-1.99 lb ai/A (~1.1  -  1.3x), respectively, residues of clomazone (and per trial averages) in/on rhubarb petioles harvested at a 41- to 44-day PHI were <0.03-0.180 (<0.033-0.114) and <0.03-0.076 (<0.03-0.062) ppm.

TABLE 6.  Summary of Residue Data from Rhubarb Field Trials with Clomazone.
Commodity
                                    Analyte
                                  Total Rate
                                   (lb ai/A)
                                  PHI (days)
                            Residue Levels (ppm)[1]

                                       
                                       
                                       
                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                  Std.  Dev.
Rhubarb Petioles
                                   Clomazone
                                   2.49-2.76
                                     41-44
                                       4
                                   <0.03
                                     0.180
                                   <0.033
                                     0.114
                                     0.046
                                     0.060
                                     0.038

                                       
                                   1.71-1.99
                                       
                                       4
                                   <0.03
                                     0.076
                                   <0.03
                                     0.062
                                     0.044
                                     0.045
                                     0.017
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.

Southern Peas.  Four field trials were conducted in the United States during the 2007 growing season in the North American Free Trade Agreement (NAFTA) Growing Zones 2 (SC; 1 trial), 4 (TN; 1 trial), and 6 (TX; 2 trials).  At each trial location, the treated plots received one pre-emergent application of a 3 lb ai/gal microencapsulated (ME) formulation of clomazone (Command(R) 3 ME) at 0.484-0.501 lb ai/A.  Applications were made using ground equipment in spray volumes of 16.9-27.6 gal/A.  Adjuvants were not added to the spray mixture at any of the trial sites.  Samples of shelled succulent pea and fresh pea plants with pods were harvested from all trials at a 62- to 77-day preharvest interval (PHI).  A second harvest occurred at a 77- to 91-day PHI to collect samples of mature dry pea plants with pods and shelled dry pea.

Samples were analyzed for residues of clomazone using a gas chromatography method with mass spectrometric detection (GC/MSD), with single ion monitoring (m/z 204), adapted from FMC No. ACG 124, as discussed above under Analytical Methodology.  The samples were stored frozen awaiting analysis, as discussed above under Storage Stability.  

Following one pre-emergent broadcast application of the 3 lb ai/gal ME formulation of clomazone at 0.484-0.501 lb ai/A, residues of clomazone in/on shelled succulent pea and fresh plants with pods and shelled dry pea and dry plants with pods and harvested at a 62- to 77-day and 77- to 91-day PHIs, respectively, were all <LOQ (<0.05 ppm).


TABLE 7.  Summary of Residue Data from Southern Pea Field Trials with Clomazone.
Commodity
                                    Analyte
                                  Total Rate
                                   (lb ai/A)
                                  PHI (days)
                            Residue Levels (ppm)[1]

                                       
                                       
                                       
                                       n
                                  Sample Min.
                                  Sample Max.
                                    LAFT[2]
                                    HAFT[2]
                                    Median
                                     Mean
                                  Std.  Dev.
Shelled Succulent Pea
                                   Clomazone
                                  0.484-0.501
                                     62-77
                                       4
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                     0.05
                                     0.05
                                      N/A
Plants With Pods, Fresh
                                       
                                       
                                       
                                       4
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                     0.05
                                     0.05
                                      N/A
Shelled Dry Pea
                                       
                                       
                                     77-91
                                       4
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                     0.05
                                     0.05
                                      N/A
Plants with Pods, Dry
                                       
                                       
                                       
                                       4
                                   <0.05
                                   <0.05
                                   <0.05
                                   <0.05
                                     0.05
                                     0.05
                                      N/A
[1]  Except for sample min/max, values reflect per trial averages; n = no. of field trials.  N/A = Not applicable.  
[2]  LAFT = lowest average field trial; HAFT = highest average field trial.

Conclusions.  The submitted field trial studies are adequate to fulfill the data requirements.  The field trials reflected the proposed use pattern.  The analytical method used was adequate for data gathering.   Samples were analyzed for clomazone, per se, which is the residue of concern.  Residues were within the proposed tolerances of 0.10, 0.3 ppm, and 0.05 ppm for clomazone in or on Brassica, head and stem, subgroup 5A, rhubarb, and southern pea commodities, respectively.  The basis for the 0.1 ppm tolerance on Brassica, head and stem, subgroup 5A, is the existing tolerance for residues of clomazone on cabbage, currently set at 0.1 ppm.  Although the EC formulation was used in the cabbage field trials, since both the cabbage residues and the broccoli residues are less than the limit of quantation, the 0.1 ppm tolerance for residues of clomazone on Brassica, head and stem, subgroup 5A, will be considered appropriate.  When the tolerance on Brassica, head and stem, subgroup 5A, is established, the tolerance on cabbage should be revoked.  The residue data for southern pea whole plants will support a tolerance for residues of clomazone on cowpea forage and hay.

860.1520:  Processing Studies

There are no processed commodities associated with the petitioned for tolerances.  This topic is not pertinent to the current petition.


860.1850/1900: Rotational Crop 
Offutt,C., 7/2/1985
Creeger, S., 8/27/1985

The minimum PBI, 9 months, has been approved by EFED (Memo, Carolyn Offutt, 7/2/85).  This restriction was based on low levels of organosoluble residues (<0.02 ppm) observed at the 10-month interval in the confined rotational crop study conducted at an application rate of 2 lbs a.i./A (Memo, Samuel Creeger, 11/23/1984).


Tolerance Recommendations

The current tolerance expression for clomazone in 40 CFR 180.425 is:

Tolerances are established for residues of the herbicide clomazone, including its metabolites and degradates, in or on the commodities in the table in this paragraph. Compliance with the tolerance levels specified in this paragraph is to be determined by measuring only clomazone, 2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone, in or on the commodity.

The current tolerance expression is in accord with our current guidance on tolerance expressions.

There are no CODEX MRLs for residues of clomazone on any commodity.  Canada has not established MRLs for the commodities in this petition.

Tolerance recommendations are found in the Executive Summary of this review.  The proposed tolerances were modified to add a significant figure, to correct the commodity definition, and to delete the unneeded tolerance on pea, southern, hay.




REFERENCES

Creeger, S., "Environmental Fate Review of Registration of Dimethazone Technical and Products, 279-GNLE, -GNLG, -GNLU, Accession Number 072819, 248476," Review by S. Hong, EPA Memorandum dated 11/23/1984

Dodd, N., "PP#4E4311.  Clomazone on Cabbage. Review of Analytical Methods and Residue Data."  D199086, EPA Memorandum dated 04/17/95, MRID 43077301.

Garbus, J., "PP#0G3919. EPA Reg. No. 279-3053. Clomazone in or on Corn R.A.C's. Request for Extension of EUP Program 279-EUP-118 and Temporary Tolerances. Evaluation of Analytical Methodology and Residue Data. MRID Nos. 416633-01 thru 4166330-13, 417251-01 and -02. DEB Nos. 7383, 7384, and 7560."  EPA Memorandum dated 11/8/91.

Garbus, J., "PP#0G3919. EPA Reg. No. 279-3053. Clomazone in or on corn R.A.C's. Additional Analytical Data: Independent Validation of Originally Proposed Enforcement Method and Response of Clomazone in FDA Multi-Residue protocols. MRID Nos. 4423253-01 and -02: DP Barcodes D178735 and D178768. CBTS Nos. 9947, 9948."  EPA Memorandum dated 8/21/92.

Offutt, C., "Estimated Enviromental Concentrations Review of FMC 57020, 279-GNLE, -GNLG, & -GNLU."  Reviewed by R. Holst and S. Hong.  EPA Memorandum dated 7/2/1985.

Perry, Mark. "PP# 7F04896. Clomazone (Reg. No. 279-3158) in/on Rice. Evaluation of    Analytical Methods and Residue Data. MRID Nos. 44348401 and 44348402. DP Barcode D242601. PC Code 125401"  EPA Memorandum to Ed Zager, dated 1/29/98. 

Vogel, Dana, "PP#9F06056.  Clomazone (i.e. Command 3ME) in/on Sugarcane.  Evaluation of Residue Data and Analytical Methods for Sugarcane.  MRID#s 449104-02-04.  Chemical 125401.  Barcode D272158."  EPA memorandum to Jim Tompkins, dated 14 Jan 2001.  



RDI:  TMorton:8/26/2013

Appendix I: International Residue Status


              Clomazone (PC Code 125401; Date of Request 8/21/13)
Summary of US and International Tolerances and Maximum Residue Limits 
Residue Definition:
US
Canada
Mexico[2]
Codex[3]
40 CFR 180.425
Plants: Clomazone, 2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone
2-(2-cholorobenzyl)-4,4-dimethyl-1,2-oxazolidin-3-one

None
Commodity[1]
Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US
Canada
Mexico[2]
Codex[3]
Brassica, stem and head subgroup 5A
0.1



Rhubarb
0.3



Pea, Southern, succulent seed
0.05



Pea, Southern, dry seed
0.05



Pea, Southern, hay
0.05













Completed:  M. Negussie; 08/26/13


[1] Includes only commodities of interest for this action.  Tolerance values should be the HED recommendations and not those proposed by the applicant.
2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.
3 * = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains.  PoP = processed postharvest treated commodity, such as processing of treated stored wheat.  (fat) = to be measured on the fat portion of the sample.  MRLs indicated as proposed have not been finalized by the CCPR and the CAC.





Appendix II

                                   Clomazone
                                    Rhubarb
                                      US
                            2 x 1.5 or 1.0 lb ai/A
 
 
Total number of data (n)
                                       8
Percentage of censored data
                                      25%
Number of non-censored data
                                       6
Lowest residue
                                     0.022
Highest residue
                                     0.180
Median residue
                                     0.042
Mean
                                     0.059
Standard deviation (SD)
                                     0.051
Correction factor for censoring (CF)
                                     0.833
 
                                       
Proposed MRL estimate
 
 
                                       
- Highest residue
                                     0.180
- Mean + 4 SD
                                     0.263
- CF x 3 Mean
                                     0.146
Unrounded MRL
                                     0.263
 
                                       
Rounded MRL
                                      0.3
                                       

Residues (mg/kg)
                                     0.030
                                       *
                                     0.035
                                       
                                     0.022
                                       *
                                     0.036
                                       
                                     0.047
                                       
                                     0.180
                                       
                                     0.067
                                       
                                     0.051
                                       

