UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES MEMORANDUM Date: 22 JUN 2005 Subject: Revised as per 30 day Error Only Registrant Comments. Sethoxydim. HED Chemistry Chapter of the Reregistration Eligibility Decision ( RED). Summary of Analytical Chemistry and Residue Data. Case No. 2600 DP Number: D318169 PC Code: 121001 Chemical Class: Cyclohexenone From: William H. Donovan, Ph. D., Chemist Reregistration Branch 3 Health Effects Division ( 7509C)

Through: Danette Drew, Branch Senior Scientist Reregistration Branch 3 Health Effects Division ( 7509C)

To: James Parker, Chemical Review Manager Reregistration Branch 1 Special Review and Reregistration Division [ 7508C]

This document was originally prepared under contract by Versar Corporation. The document has been reviewed by HED and revised to reflect current OPP policies. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 2 of 101 Executive Summary 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. The current formulations of sethoxydim are comprised of emulsifiable concentrates ( ECs). The active ingredient ( ai) sethoxydim in these formulations range from 13 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.

The qualitative nature of the 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 in plants and livestock are the combined residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety ( calculated as sethoxydim). For risk assessment purposes, the residues in water are parent plus degradates. The degradates which are expected to be found in water are the sulfoxide and sulfone derivatives of the parent ( MSO and MSO2) along with M1S ( loss of ethoxy group on imino nitrogen) and M2S ( formation of oxazole ring).

BASF Wyandotte Corporation's ( BWC's) Methods No. 30, 30G, 30H and A9003 are adequate analytical methods for data collection and/ or enforcement of tolerances for residues of sethoxydim and its metabolites in or on plant and animal commodities. In these methods, residues are determined by gas liquid chromatography with flame photometric detection ( GLC/ FPD). Method 30 is included as Method I in PAM II. Methods 30G, 30H and A9003 have been submitted for publication in PAM II as lettered methods.

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, and sheep at 1.0 ppm ( 2.0 ppm in meat byproducts of poultry); 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.

Crop field trial and processing studies have been submitted by the registrant. In the Phase IV review for sethoxydim, HED requested magnitude of residue studies for various crops to fulfill data gaps identified during review. Subsequent to the completion of the Phase IV review, the validity of certain field studies was questioned because residue samples from those studies had been analyzed in a particular contract laboratory, Craven Labs. As a result, the Agency issued a DCI to replace crop field trial data generated by Craven Labs for alfalfa hay, artichoke, succulent beans, dry beans, broccoli, cabbage, mustard greens, cotton, flax, peppers, tomatoes, grapes, lentils, peanuts, succulent peas, dry peas, potatoes, raspberry, soybeans, strawberry and sugar beets. Additionally, the DCI requested replacement data for bean and grape processing studies. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 3 of 101 Only data not generated by Craven Labs are discussed in this document. In general, residue data support the existing tolerances.

Regulatory Recommendations and Residue Chemistry Deficiencies 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 plant and animal, food and feed commodities. HED supports these tolerances, provided that the following deficiencies and data gaps are resolved:

1) Crop field trials Safflower  Two additional residue studies from Region 10 are needed.

2) Tolerance Revocation The following tolerances should be revoked:

 Flax, straw  Flax, meal  Peanut, soapstock  Tomato, dry pomace  Tomato, concentrated products  Citrus, molasses 3) Tolerance Increases The maximum residues detected in the crop field samples are higher than the tolerance for the following commodities:

 Clover hay ( maximum residue of 50.7 ppm, tolerance of 50 ppm). Increase tolerance level to 55 ppm.  Cranberries ( maximum residue of 2.2 ppm, tolerance of 2 ppm). Increase tolerance level to 2.5 ppm. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 4 of 101 S H 3 C CH 3 OH CH 3 O N O CH 3 DME Background The PC Code and nomenclature of sethoxydim are listed below in Table 1, the chemical names and structures of the metabolites are listed in Table 2, and the physicochemical properties of sethoxydim are listed in Table 3.

TABLE 1. Sethoxydim Chemical Structure Common name Sethoxydim, MS Company experimental name BAS 9052 H IUPAC name ( ± ) ( EZ) 2( 1 ethoxyiminobutyl) 5[ 2( ethylthio) propyl] 3 hydroxycyclohex 2 enone CAS name ( ± )  2[ 1( ethoxyimino) butyl] 5[ 2( ethylthio) propyl] 3 hydroxy 2 cyclohexen 1 one CAS # 74051 80 2 TABLE 2. Chemical names and structures of metabolites of sethoxydim Common name Chemical Name Structure DME 3[ 2( ethylsulfonyl) propyl] pentanedioic acid dimethyl ester Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 2. Chemical names and structures of metabolites of sethoxydim Common name Chemical Name Structure 5 of 101 DME OH MSO M1S DME OH 3[ 2( ethylsulfonyl) propyl] 3 hydroxypentanedioic acid dimethyl ester MSO; sethoxydim sulfoxide 2[ 1( ethoxyimino) butyl] 5[ 2 ( ethylsulfinyl) propyl] 3 hydroxy 2 cyclohexen 1 one M1S Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 2. Chemical names and structures of metabolites of sethoxydim Common name Chemical Name Structure 6 of 101 5 OH MSO MSO2 M1SO 5 OH MSO MSO2; sethoxydim sulfone 2[ 1( ethoxyimino) butyl] 5[ 2 ( ethylsulfonyl) propyl] 3 hydroxy 2 cyclohexen 1 one M1SO 2[ 1( imino) butyl] 5[ 2 ( ethylsulfinyl) propyl] 3 hydroxy 2 cyclohexen 1 one Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 2. Chemical names and structures of metabolites of sethoxydim Common name Chemical Name Structure 7 of 101 M1SO2 M2SO OH MSO2 M1SO2 M2SO 6[ 2( ethylsulfinyl) propyl] 6,7 dihydro 2 propyl 4( 5H) benzoxazolone 5 OH MSO2; 5 hydroxy sethoxydim sulfone 2[ 1( ethoxyimino) butyl] 5[ 2 ( ethylsulfonyl) propyl] 3,5 dihydroxy 2 cyclohexen 1 one Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 2. Chemical names and structures of metabolites of sethoxydim Common name Chemical Name Structure 8 of 101 M2S MGSO MGSO2 M2S MGSO MGSO2 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 2. Chemical names and structures of metabolites of sethoxydim Common name Chemical Name Structure 9 of 101 M2SO2 OH M2SO2 M2SO2 6[ 2( ethylsulfonyl) propyl] 6,7 dihydro 2 propyl 4( 5H) benzoxazolone 5 OH M2SO2 Table 3. Physical and Chemical Properties of Sethoxydim Property Description Reference ( MRID#)

Color brown 41607203 Physical state viscous liquid 41607203 Odor garlic like 41607203 Boiling Point > 130

C at 6 x 10 1 mm Hg 41607203 Density, bulk density, or specific gravity 1.058 specific gravity at 20

C 41607203 Solubility Water at 25

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 20

C: freely soluble (> 10 3 g/ 100 mL). 41475201 41510601 Vapor pressure 1.6 x 10  7 mm Hg at 25

C 00047647 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 Table 3. Physical and Chemical Properties of Sethoxydim Property Description Reference ( MRID#)

10 of 101 Dissociation constant pKa is 4.6 at pH 4.5 and 25

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 20

C 41607203 Stability stable at normal temperatures ( 24

C) and in the presence of metals ( zinc or iron powder); unstable at elevated temperatures ( 54

C) and in the presence of sunlight. 41607203 860.1200 Directions for Use Product List A product registration query of the Agency's OPPIN database identified 5 active sethoxydim end use products ( EPs) registered for use on food/ feed sites. All five end products are registered to BASF Corporation and are intended for use on a variety of crops. The EPs are listed in Table 4 below. Additionally, the query identified 19 Special Local Needs ( SLN) registrations and 73 Section 18 Emergency Exemption Registrations. The most recent Section 18 Emergency Exemption is from 2003 ( 03ND15). The remainder Section 18 Emergency Exemptions are from 1982 to 2002.

TABLE 4. Sethoxydim End Use Products ( EPs) with Food/ Feed Uses.

EPA Reg. No. Formulation1 Registrant Product Name2 7969 58 EC  18.0% ai BASF Corporation Poast ® Herbicide ManifestJ Herbicide ConcludeJ Herbicide Poast ® S Herbicide 7669 88 EC  13.0% ai BASF Corporation Poast Plus ® Herbicide Vantage ® Herbicide Rezult ® Herbicide Torpedo ® Herbicide 7669 121 EC  16.2% ai BASF Corporation UltimaJ 160 Herbicide 7969 129 EC  43.0% ai BASF Corporation Poast ® 3.5 Herbicide Conclude ® Ultra G Herbicide ( 43.3% ai) Poast ® HC Herbicide 7969 176 EC 25.5% ai BASF Corporation Poast ® 2.0 Herbicide 1. EC= Emulsifiable concentrate 2. The product name in bold is the current product name according to OPPIN. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 11 of 101 Use Patterns Table 5 presents a summary of the use directions based on the supported uses as specified in the Sethoxydim Use Closure Memo ( A. Johnson, 9/ 14/ 2004). For the purposes of reregistration, the registered food/ feed uses of sethoxydim have been re evaluated for all the plant and animal commodities for which tolerances exist. A tabular summary of the chemistry science assessments is presented in Table 6. The conclusions listed in Table 6 regarding the reregistration eligibility of sethoxydim food/ feed uses are based on the use patterns registered by the producer. When end use product data call ins ( DCIs) are developed ( e. g., at issuance of the RED), SRRD should ensure that all end use product labels ( e. g., MAI labels, SLNs, and products subject to the generic data exemption) are consistent with the basic producer labels.

Table 5. Summary of Sethoxydim Use Directions Crop Minimum Time From Application to Harvest ( PHI) (# of days) Maximum Rate Per Acre Per Application ( lb ai/ acre) Maximum Rate Per Acre Per Season ( lb ai/ acre)

Alfalfa, birdsfoot trefoil, and sanfoin ( dried) 14 0.47 1.2 Alfalfa, birdsfoot trefoil, and sanfoin ( undried) 7 0.47 1.2 Apricot 25 0.47 0.94 Artichoke, Globe 7 0.47 0.94 Asparagus 1 0.47 0.94 Avacado ( nonbearing) 365 0.47 1.4 Beans ; Dry, Succulent 30 15 0.47 0.75 Beet ( Garden) 60 0.47 0.94 Blueberry 30 0.47 0.94 Brassica ( Crop Group 5) 30 0.28 0.56 Bulb Vegetables ( Crop Group 3) 30 0.28 0.84 Caneberries ( Crop Subgroup 13A) 45 0.47 0.94 Canola/ Crambe/ Rapeseed 60 0.47 0.94 Carrot 30 0.47 0.94 Cherries ( sweet and sour) 25 0.47 0.94 Christmas tree farms n/ a 0.47 0.56 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 Table 5. Summary of Sethoxydim Use Directions Crop Minimum Time From Application to Harvest ( PHI) (# of days) Maximum Rate Per Acre Per Application ( lb ai/ acre) Maximum Rate Per Acre Per Season ( lb ai/ acre)

12 of 101 Citrus ( Crop Group 10) 15 0.47 1.9 Clover 7 ( before grazing, feeding, or cutting for undried forage) 0.47 1.2 Clover hay 20 ( before grazing, feeding, or cutting for dry hay) 0.47 1.2 Corn ( Poast ® protected field corn) 60 ( grain or fodder) 45 ( forage and silage) 0.28 0.56 Corn ( Poast ® protected sweet corn) 45 ( grain or fodder) 30 ( fresh sweet corn or forage and silage) 0.28 0.56 Cotton 40 0.47 1.4 Cranberry 60 0.47 0.94 Curcubits ( Crop Group 9) 14 0.28 0.56 Date ( nonbearing) 365 0.47 1.4 Deciduous trees, Nonfood Crop Areas, Fallow Land n/ a 0.47 n/ a Fescue ( tall) n/ a 0.47 n/ a Fig ( nonbearing) 365 0.47 1.4 Flax 75 0.28 0.75 Fruiting Vegetables ( Crop Group 8) 20 0.28 0.84 Grape 50 0.47 0.94 Head and Petiole Type Vegetables ( Crop Subgroup 4B) 30 0.28 0.56 Horseradish 60 0.47 0.94 Leafy Vegetables ( Crop Group 4) 15 0.28 0.56 Lentil 50 0.47 0.75 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 Table 5. Summary of Sethoxydim Use Directions Crop Minimum Time From Application to Harvest ( PHI) (# of days) Maximum Rate Per Acre Per Application ( lb ai/ acre) Maximum Rate Per Acre Per Season ( lb ai/ acre)

13 of 101 Lingonberry, Salal, Juneberry 45 0.47 0.94 Mint 20 0.47 0.94 Nectarine 25 0.47 0.94 Non bearing food crops n/ a 0.47 0.56 Nursery plantings n/ a 0.47 0.56 Olives ( nonbearing) 365 0.47 1.4 Orchard floor middles n/ a 0.09 0.09 Ornamentals n/ a 0.47 0.56 Peach 25 0.47 0.94 Peanut 40 0.28 0.47 Peas, Dry Succulent 30 15 0.47 0.47 0.75 Pistachio 15 0.47 1.9 Plum ( nonbearing) 365 0.47 1.4 Pome fruits ( Crop Group 11) 14 0.47 1.4 Pomegranate ( nonbearing) 365 0.47 1.4 Potatoes, Field Sweet ( East US) Sweet ( West US) 30 30 60 0.47 0.47 0.28 0.94 0.94 0.94 Prune ( nonbearing) 365 0.47 1.4 Rights of way n/ a 0.47 0.56 Roadsides n/ a 0.47 0.56 Safflower 30 0.47 0.94 Set Aside Conservation Land n/ a 0.47 1.4 Soybean 75 0.47 0.94 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 Table 5. Summary of Sethoxydim Use Directions Crop Minimum Time From Application to Harvest ( PHI) (# of days) Maximum Rate Per Acre Per Application ( lb ai/ acre) Maximum Rate Per Acre Per Season ( lb ai/ acre)

14 of 101 Strawberry 7 0.47 0.47 Sugar beet 60 0.47 0.94 Sunflower 70 0.47 0.47 Tobacco 42 0.28 0.75 Tree Nuts ( Crop Group 14) 15 0.47 1.9 Tuberous and Corm Vegetables ( Crop Subgroup 1C) 30 0.47 0.94 Turf/ lawns n/ a 0.47 0.56 Wildflowers n/ a 0.47 0.56 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 15 of 101 TABLE 6. Residue Chemistry Science Assessment for Reregistration of Sethoxydim ( 121001).

GLN Data Requirements Current Tolerances ( ppm) [ § 180.412] Additional Data Needed? MRID Nos.

860.1200: Directions for Use N/ A = Not Applicable No N/ A 860.1300: Nature of the Residue  Plants ° Soybeans N/ A No 92166094 1 ° Tomatoes N/ A No 00148007 2 ° Sugar Beets N/ A No 43144501 3 43467001 4 860.1300: Nature of the Residue  Animals ° Goat N/ A No 00153602 ( summary in 92166046) 5 ° Hen N/ A No 00155129 ( summary in 92166047) 6 860.1340: Residue Analytical Method ° Plant Commodities N/ A No Not available 7 ° Animal Commodities N/ A No Not available 7 860.1360: Multiresidue Method N/ A No 41980701 8 860.1380: Storage Stability Data ° Plant Commodities N/ A No 43801401 9 00130578 10 ° Animal Commodities N/ A No 43223401 11 860.1400: Magnitude of the Residue  Water, Fish, and Irrigated Crops N/ A N/ A N/ A 860.1460: Magnitude of the Residue  Food Handling N/ A N/ A N/ A 860.1480: Magnitude of the Residue  Meat, Milk, Poultry, Eggs ° Cattle, goat, hog, horse, sheep, & poultry fat and meat 0.2 No 00153602 and 0042808 ( summary in 92166049) 12 ° Cattle, goat, hog, horse, & sheep  meat byproducts 1 No ° Poultry  meat byproducts 2 No ° Egg 2.0 No ° Milk 0.5 No 860.1500: Crop Field Trials ° Alfalfa forage 40 No 00155129 13 40515801 13 ° Alfalfa hay 40 No 41970901 14 ° Almonds 2 No 41428501 15 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 6. Residue Chemistry Science Assessment for Reregistration of Sethoxydim ( 121001).

GLN Data Requirements Current Tolerances ( ppm) [ § 180.412] Additional Data Needed? MRID Nos.

16 of 101 ° Apricot 0.2 No 41236404 16 ° Artichoke, globe 5 No 43973101 17 ° Asparagus No 42487401 18 42487402 18 42834201 19 42834202 19 43051701 20 ° Bean, dry, seed 20 No 43801413 21 ° Bean, forage 15 No 43801411 21 43801413 21 ° Bean, hay 50 No 43801411 21 43801413 21 ° Bean, succulent 15 No 43801411 21 ° Beet, garden 1 No None 22 ° Beet, sugar, roots 1 No 155129 23 and 40639101 24 ( summary in 92166067), 40639102 24 ° Beet, sugar, tops 3 No 155129 23, 40639101 24, 40639102 24 ° Blueberry 4 No 40492604 ( summary in 92166072) 25 ° Caneberry subgroup 13A 5 No 4397270125 00157187 ( summary in 92166066) 26 ° Canola/ rapeseed 35 No 42074201 27 ° Carrots 1 No 42195001 24, 28 ° Cherry, sweet 0.2 No 41236401 29 ° Cherry, tart 0.2 No 41236401 29 ° Citrus 0.5 No 40492601 40492602 40492603 ° Clover forage 35 No 42353601 30 ° Clover hay 50 No 42353601 30 ° Coriander 4 No None 31 ° Corn, field, grain 0.5 No 43178701 32 43455701 32 ° Corn fodder 2.5 No 43178701 32 43455701 32 ° Corn forage 2 No 43178701 32 43455701 32 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 6. Residue Chemistry Science Assessment for Reregistration of Sethoxydim ( 121001).

GLN Data Requirements Current Tolerances ( ppm) [ § 180.412] Additional Data Needed? MRID Nos.

17 of 101 ° Corn, sweet, forage 3 No 45100501 33 ° Corn, sweet, kernel plus cob with husks removed 0.4 No 45100501 33 ° Corn, sweet, stover 3.5 No 45100501 33 ° Cotton, undelinted, seed 5 No 43062205 34 ° Cranberry 2 No 41627001 35 ° Flax, seed 5 No 43801409 21 ° Flax, straw 2 No 43801409 21 ° Grape 1 No 43801410 21 ° Horseradish 4 No None 36 ° Juneberry 5 No None37 ° Lentil, seed 30 No None 21 ° Lingonberry 5 No None 37 ° Nectarine 0.2 No 41236404 16 ° Peach 0.2 No 41236402 16 ° Peanut 25 No 43801408 21 9216606326 ° Pea, dry, seed 40 No 43801414 21 ° Pea, field, vines ( forage) 20 No 43801414 21 43801415 21 ° Pea, field, hay 40 No 43801414 21 43801415 21 ° Pea, succulent 10 No 43801415 21 ° Peppermint, tops ( stems and leaves) 30 No 42101701 38 ° Pistachio 0.2 No None 39 ° Pome Fruit 0.2 No 40576101 40576102 ° Rhubarb 0.3 No40 41072001 ° Salal 5 No None 37 ° Safflower 15 Yes 41 44864501 ° Soybean ( seed) 16 No 43801412 21 100535 43 ° Soybean, hay 10 No 153602 21 43801412 21 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 6. Residue Chemistry Science Assessment for Reregistration of Sethoxydim ( 121001).

GLN Data Requirements Current Tolerances ( ppm) [ § 180.412] Additional Data Needed? MRID Nos.

18 of 101 ° Spearmint, tops ( stems and leaves) 30 No 42101701 38 ° Strawberry 10 No 41342801 ° Sunflower, seed 7 No MRID 00131857 ( Summary in MRID 92166068) 23; Accession Number 07342444 ° Tree nut 0.2 No 41428502 15 41428503 15 41428501 15 ° Tuberous and corm vegetable crop subgroup 4 No 43801407 21 ° Vegetable, brassica, leafy, group 5 5 No 43801403 45 43801404 45 43801405 45 ° Vegetable, bulb, group 3 1 No 40783000 46 40783001 46 40783002 46 ° Vegetable, curcubit, group 9 4 No 43062202 34 43062203 34 43282401 47 00162812 ( summary in 92166055) 26 ° Vegetable, fruiting, group 8 4 No 43062201 34 43801402 45 43801406 21 00148007 ( summary in 92166057) 26 ° Vegetable, leafy, except brassica, group 4 4 No 40375701 ( summary in 92166059) 26 40375702 ( summary in 92166061) 26 40375703 ( summary in 92166058) 48 40375704 ( summary in 92166060) 48 860.1520: Processed Food/ Feed ° Alfalfa meal N/ A No 42816801 49 ° Apple, dried and wet pomace 0.8 No 92166087 40576103 ° Beet, sugar, molasses 10 No 42839001 50 41966101 51 ° Canola/ rapeseed, meal 40 No 42074202 27 ° Citrus, molasses and dried pulp 1.5 No 40492605 ( Summary in 92166086)

° Corn, wet and dry milling N/ A No 43178702 32 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 TABLE 6. Residue Chemistry Science Assessment for Reregistration of Sethoxydim ( 121001).

GLN Data Requirements Current Tolerances ( ppm) [ § 180.412] Additional Data Needed? MRID Nos.

19 of 101 ° Cotton, seed, soapstock 15 No 00127281 ( Summary in 92166078) 26 ° Flax, meal 7 No None ° Grape, raisin 2 No 43801416 21 ° Peanut, soapstock 75 No 92166081 ( Summary in 92166078) 26 ° Peppermint, oil N/ A No 42101702 38 ° Potato, flakes/ granules 8 No 40195102 ( Summary in 92166082) 26 ° Potato, processed potato waste 8 No 40195102 ( Summary in 92166082) 26 ° Safflower, meal and refined oil N/ A No 44864501 46496901 42 ° Soybean, meal, hulls and refined oil N/ A No 00100535 ( Summary in 92166083) 26 ° Spearmint, oil N/ A No 42101702 38 ° Sunflower, meal and refined oil 20 ( for sunflower meal) No 00131857 ( Summary in 92166085) 26 ° Tomato, concentrated products 24 No 00162633 ( Summary in 92166080) 26 ° Tomato, dried pomace 12 No 00162633 ( Summary in 92166080) 26 860.1650 Submittal of Analytical Reference Standards N/ A No52 N/ A 860.1850: Confined Accumulation in Rotational Crops N/ A No Accession No. 42825 53 860.1900: Field Accumulation in Rotational Crops N/ A No 41510612 53 1. PP# 3F2904, K. Arne, 6/ 26/ 85; Phase V Review, CBRS 17851, L. Cheng, 4/ 4/ 97 2. PP# 5F3284/ 5H5475, C. Deyrup, 10/ 9/ 85; Phase V Review, CBRS 17851, L. Cheng, 4/ 4/ 97 3. D200367, L. Cheng, 9/ 16/ 94 4. D210046, L. Cheng, 1/ 3/ 95 5. PP# 3F2904, K. Arne, 6/ 26/ 85; Phase V review, CBRS 17851, L. Cheng, 4/ 4/ 97; Phase IV, L. Cheng, 2/ 25/ 91 6. Phase V review, CBRS 17851, L. Cheng, 4/ 4/ 97; Phase IV, L. Cheng, 2/ 25/ 91 7. Reviews were found in: D210060, D210062, D208310, & D208312, M. I. Rodriguez, 7/ 24/ 95; PP# 2F2670, K. Kissler, 4/ 1/ 83; D257559, N. Dodd, 1/ 24/ 02; PP# 3F2904, 11/ 2/ 88, S. Malak; S. Malak, 11/ 7/ 88; D172349, W. D. Wassell, 2/ 11/ 92, memo from J. Onley, 4/ 1/ 83 and letter from M. Bradley, 5/ 4/ 90 8. PP# 0F3855, M. J. Nelson, 10/ 9/ 91 9. D219970, CBRS 16310, L. Cheng, 4/ 9/ 96. Also summarized in D256970, N. Dodd, 8/ 9/ 01 10. Phase IV, L. Cheng, 2/ 25/ 91 11. D203246, L. Cheng, 8/ 15/ 94 12. Other study reports were reviewed by EPA; however, the MRIDs were not provided. Reviews found in D257559, N. Dodd, 1/ 24/ 02, D178826, C. Swartz, 8/ 20/ 92, and Phase IV, L. Cheng, 2/ 25/ 91. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 20 of 101 13. D209952, L. Cheng, 1/ 19/ 95 14. D200363, L. Cheng, 8/ 22/ 94 15. PP0F3855, M. J. Nelson, 2/ 7/ 91 and D256970, N. Dodd, 8/ 9/ 01. 16. PP9F3804/ PP9H5589, S. Inasi, 8/ 8/ 90 17. D225427, W. Cutchin, 6/ 12/ 98; D238439, W. Cutchin, 4/ 8/ 98. 18. D183351, D. Davis, 12/ 4/ 92 19. D193362, D. Davis, 8/ 4/ 93 20. D197875, D. Davis, 4/ 21/ 94 21. D237724, L. Cheng, 7/ 28/ 97 22. D225427, W. Cutchin, 6/ 12/ 98 23. Phase IV, L. Cheng, 2/ 25/ 91 24. D185410, M. I. Rodriguez, 8/ 25/ 93 25. D225427, W. Cutchin, 6/ 12/ 98; D238439, W. Cutchin, 4/ 8/ 98. 26. Phase IV, L. Cheng, 2/ 25/ 91 27. D171714, D171716, D171724, B. Schneider, 9/ 21/ 92 28. D174374, M. I. Rodriguez, 8/ 7/ 92 29. PP9F3804/ PP9H5589, S. Inasi, 8/ 8/ 90 30. D179955 & D179957, M. I. Rodriguez, 9/ 16/ 93 31. Data translated from parsley, W. Cutchin, 4/ 8/ 98. 32. D210060, D210062, D208310, & D208312, M. I. Rodriguez, 7 24 95 33. D266208/ D266210, N. Dodd, 7/ 5/ 02 34. D198048, L. Cheng, 4/ 26/ 94 35. PP0E3909, M. J. Nelson, 2/ 14/ 91 36. Tolerance for horseradish was established based on existing residue data from sugar beets, carrots, potatoes and sweet potatoes. D251542, G. Herndon, 12/ 10/ 98. 37. Residue data on blueberry and caneberry were used to support use on juneberry, lingonberry and salal. D278583, N. Dodd, 7/ 19/ 02 38. D172349, W. D. Wassell, 2/ 11/ 92 39. D256970, N. Dodd, 8/ 9/ 01. Residue data for sethoxydim on almonds ( nuts and hulls) ( MRID 41428501), pecans ( MRID 41428502), and walnuts ( MRID 41428503) were used in lieu of residue data on pistachios to support the tolerance on pistachios. 40. The tolerance for rhubarb is a regional registration. 41. Additional crop field trials are needed ( 2 trials in Region 10) 42. Storage stability data reported in MRID 46496901 demonstrate that sethoxydim and its metabolites in soybean processed fractions ( crude oil, refined oil, and soapstock) remain stable for at least 29 months under freezer storage conditions (<  5 C). These results may be translated to cover safflower oil. 43. D182749, B. Schneider, 11/ 23/ 92 44. RCB# 943 and # 944, M. Firestone, 7/ 17/ 85 45. D219970, L. Cheng, 4/ 9/ 96 46. D185410, M. I. Rodriguez, 8/ 25/ 93 47. D205049, L. Cheng, 12/ 1/ 94 48. D172550, M. Peters, 6/ 24/ 92 49. D192620, F. Suhre, 4/ 19/ 94 50. D182748, D182746, D182747, D193019, D193020, D193021, W. Wassell, 8/ 6/ 93 51. D167888, D167906, D167908, W. Wassell, 2/ 19/ 92 52. Replenish standards as requested by the repository 53. D189273, G. Kramer, 8/ 3/ 93 860.1300 Nature of the Residue  Plants The qualitative nature of the residue in plants is adequately understood based on soybean, tomato and sugar beet metabolism studies. These studies indicate that sethoxydim is rapidly metabolized Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 21 of 101 in plants to a multitude of cyclohexenone derivatives including the corresponding parent sulfoxide, parent sulfone, their hydroxylated and desethoxylated analogs, and oxazole compounds; very little (

0.5%) sethoxydim is left unmetabolized. Since metabolism studies in three dissimilar crops indicate a similar metabolic route, HED has concluded that no additional metabolism studies are required. 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). Detailed summaries of the metabolism studies for soybean, tomatoes, and sugar beets are presented below. Metabolism studies were also conducted on alfalfa ( MRID 00153602, summary in MRID 92166044) and cotton ( MRID 92166095), however, these studies are not discussed in the document as they are not necessary for the determination of the qualitative nature of residue in plants.

For convenience, the following abbreviations will be used in this document to refer to sethoxydim and its metabolites:

Sethoxydim = MS = 2[ 1( ethoxyimino) butyl] 5[ 2( ethylthio) propyl] 3 hydroxy 2 cyclohexen 1 one DME = 3[ 2( Ethylsulfonyl) propyl] pentanedioic acid dimethyl ester DME OH = 3[ 2( Ethylsulfonyl) propyl] 3 hydroxypentanedioic acid dimethyl ester MSO = ( Sethoxydim sulfoxide metabolite. It is converted to the final analyte DME.) = 2 [ 1( Ethoxyimino) butyl] 5[ 2( ethylsulfinyl) propyl] 3 hydroxy 2 cyclohexen 1 one MSO2 = 2[ 1( Ethoxyimino) butyl] 5[ 2( ethylsulfonyl) propyl] 3 hydroxy 2 cyclohexen 1 one M1SO = 2[ 1( Imino) butyl] 5[ 2( ethylsulfinyl) propyl] 3 hydroxy 2 cyclohexen 1 one M2SO = 6[ 2( Ethylsulfinyl) propyl] 6,7 dihydro 2 propyl 4( 5H) benzoxazolone M2SO2 = 6[ 2( Ethylsulfonyl) propyl] 6,7 dihydro 2 propyl 4( 5H) benzoxazolone 5 OH MSO2 = ( The most common hydroxylated plant metabolite. It is converted to the final analyte DME OH) = 2[ 1( Ethoxyimino) butyl] 5[ 2( ethylsulfonyl) propyl] 3,5 dihydroxy 2 cyclohexen 1 one Other metabolites that were identified, but did not have chemical names provided include: M2S M1SO2 5 OH MSO 6 OH M2SO2 M1S 6 OH M2SO Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 22 of 101 MGSO MGSO2 nor MS nor MSO nor MSO2 Soybeans MRID 92166094 ( PP# 3F2904, K. Arne, 6/ 26/ 85; Phase V Review, CBRS 17851, L. Cheng, 4/ 4/ 97)

Sethoxydim was labeled with carbon 14 at the C 4 of the ring and had a specific activity of 8.213 Ci/ mol ( 55.67 x E9 dpm/ g). Chemical purity of the compound was not given. Soybean plants received applications of sethoxydim at a rate of either 0.892 lb ai/ A ( 0.95x rate) or 0.5 lb ai/ A. Forage was sampled at 14 days after treatment and seeds were harvested 89 days after treatment. Immediately after harvesting, samples were placed in dry ice and transported to a laboratory refrigerator ( 20  C) and kept there until analysis ( storage interval estimated to be about 2 years). In fortified seed ( levels not given), average recoveries were 98 ± 12% for parent, 100 ± 8% for MSO2, 98 ± 8% for M2SO2, and 81 ± 11% for 5 OH MSO2 after freezer storage of 24 months. HED has determined that sethoxydim and its sulfoxide and sulfone metabolites are stable in soybeans for 3 years ( D219970, L. Cheng, 4/ 9/ 96).

Characterization and identification of metabolites was completed through 2 dimensional thin layer chromatography ( TLC) and mass spectroscopy ( comparison with standards). In soybean forage, a total of 62% of total radioactive residue ( TRR) was identified and in soybean seed, a total of 72% of TRR was identified. Of the remaining residues which were not identified, the largest fraction was the aqueous fraction ( 16% in soybean forage and 10% in soybean seed); however, the individual fractions accounted for less than 10% of TRR.

The radioactive residues identified in soybean forage were MSO, MSO2, M2SO, M2SO2, M2S, M1SO, M1SO2, MGSO, and MGSO2. MGSO and MGSO2 are ring opened metabolites only found in the forage. Metabolites MSO and M2SO were the major residues identified at 31.3% TRR ( 1.16 ppm) and 13.7% TRR ( 0.51 ppm), respectively. The radioactive residues identified in soybean seed included MSO, MSO2, M2SO, M2SO2, 5 OH MSO, and 5 OH MSO2. Metabolites 5 OH MSO and 5 OH MSO2 were the major residues identified in soybean seeds at 23.0% TRR ( 0.119 ppm) and 12.2% TRR ( 0.063 ppm), respectively. The amounts of radioactive residues were higher in forage than in seeds.

Tomatoes MRID 00148007 ( PP# 5F3284/ 5H5475, C. Deyrup, 10/ 9/ 85; Phase V Review, CBRS 17851, L. Cheng, 4/ 4/ 97)

Sethoxydim was labeled at the C 4 position with carbon 14 with a specific activity of 13.16 mCi/ mmole. Tomato plants were treated at the 4 6 trifoliate stage ( 18 inches) twice with sethoxydim 14 days apart. The application rate was 0.5 lb ai/ A each time. Samples were Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 23 of 101 collected at Days 7, 21, 35, 49 and 66 after last application. The interval between treatment of tomatoes and sample analysis was about 24 months. HED has determined that sethoxydim and its sulfoxide and sulfone metabolites are stable in tomatoes for 3 years ( D219970, L. Cheng, 4/ 9/ 96).

The treated tomatoes were homogenized with methanol and filtered to yield a methanolic extract. After concentration of the filtrate, calcium hydroxide was added to precipitate protein. After filtration and concentration, the filtrate was acidified to pH 2 and extracted with methylene chloride. The acidic aqueous layer was heated at reflux, cooled, and partitioned with methylene chloride.

Metabolites in the major fraction ( methylene chloride) were identified by comparison to reference standards using TLC or high performance liquid chromatography ( HPLC). Depending on the sampling interval, between 54 and 72% of TRR in tomato fruit was identified. Residues identified in the tomato fruit included MSO, MSO2, M1SO, M2SO, M2SO2 and 5 OH MSO2. The major metabolites were also confirmed by mass spectroscopy. The total amount of metabolites in the methylene chloride fraction from day 35 was also confirmed by Method 30B, which measures all metabolites containing the substituted cylcohexenone group and gave a result of 53.4% of the TRR. When the aqueous phases ( day 35, 49, 66) were subjected to Method 30B, < 3% of the TRR contained the substituted cylcohexenone group.

Sugar beets MRID 43144501, D200367, L. Cheng, 9/ 16/ 94; MRID 43467001, D210046, L. Cheng, 1/ 3/ 95 A metabolism study with sugar beets ( MRID 00131857; summary in MRID 92166042) was originally conducted using a dose equivalent to 0.45 lb ai/ A. As the dose applied only represented about ½ the registered seasonal rate, HED requested that another sugar beet study be conducted at the registered use rate ( L. Cheng, 2/ 25/ 91). In response, a new sugar beet study was submitted ( MRID 43144501). In this study, sethoxydim was labeled with carbon 14 at the C 4 of the cylcohexene ring ( 94% radiopurity and a specific activity of 60.97  Ci/ mg). A spray solution was prepared in crop oil concentrate and water in proportions similar to a typical spray tank mixture. One hundred and 13 days after planting, 6 sugar beet plants were sprayed until the foliage was thoroughly covered with formulated sethoxydim at a rate equivalent to 1 lb ai/ A. Six plants also served as control.

Samples were collected at 0, 60, and 100 days after treatment. The plants were separated into tops and roots. The samples were stored frozen at  20  C at until analysis. Chemical analysis lasted 18 months ( 6/ 92 to 12/ 93).

Crop samples were extracted with methanol and aqueous methanol that yielded ca 90 93% TRR. The fibrous residue left was then extracted with methanol: chloroform and acetone that yielded 0.4 0.5% TRR. The methanol and aqueous methanol fractions were combined, reduced in volume, diluted with water, and extracted at pH 2 with dichloromethane. The organosoluble residues were separated into neutral and acidic compounds by partitioning with aqueous sodium hydroxide followed by back extraction into hexane and then dichloromethane. The aqueous fractions were combined, passed through Amberlite XAD 4 columns, treated with pectinase, and Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 24 of 101 the released exocons were extracted into dichloromethane. Residues remaining in the aqueous solution were methylated and then extracted into dichloromethane. The final aqueous phase was subjected to the residue analytical method to determine any sethoxydim related compounds left. The non extractable residues ( 9% TRR for tops and 6% for roots) were reacted with polysaccharide hydrolyzing enzymes ( cellulase, pectolyase, driselase).

One and/ or two dimensional TLC analyses were used for the separation and detection of sethoxydim metabolites ( through Rf's of known standards). Regions of silica gel corresponding to individual metabolites were scraped off and the radioactivity was determined by a liquid scintillation counter. Aliquots of liquid or TLC silica gel samples were mixed with a scintillation cocktail and assayed directly and fibrous residues were oxidized and the trapped carbon dioxide was mixed with a scintillation cocktail and then assayed. DME, DME OH, MSO, and MSO2 were detected by UV 365 nm after spraying with 0.01% purimulin in 80% acetone, and the others by 254 nm directly without spraying. The identity of many metabolites was confirmed by HPLC retention time and/ or LC MS.

Initial dichloro methane extractions ( DCM I: acidic M type, & DCM II: neutral M1, M2 type) removed about half or more of the TRR. Other fractions that released any significant amount of TRR (> 10% TRR) were from the methylation and oxidation/ methylation step.

The metabolites identified and characterized included sethoxydim, MSO2, 5 OH SO2, 5 OH SO, MSO, M2SO2, M2SO, 6 OH M2SO2, M1SO2, M1S, M1SO, M2S, and 6 OH M2SO.

The registrant submitted photographs of sample TLC's, HPLC's, and LC MS to support metabolite characterization. Two dimensional TLC's were submitted to support structural assignment of the residues extracted into the early dichloromethane fractions ( DCM I & II) for sugar beet top and root. Identification was through comparison of Rf values of various mixtures of known standards. The extracted samples were carried through 2 dimensional TLC and mixtures of certain standards and samples were analyzed in two different solvent systems. HPLC's for standards MSO2, MSO, M2SO2, M1SO2, and M2SO were submitted. However, mass specs of the MSO2 ( a major component) fractions isolated from sugar beet tops and roots were not superimposable with those of the standards; there were either extraneous peaks ( see p 206) or vastly different ion ratios ( p 207). In a follow up submission ( MRID 43467001) the registrant indicated that the extraneous peaks seen in the mass spectra were due to impurities in the sugar beet samples. The performing laboratory re analyzed reserved samples of sugar beet top and root. Mass spectra of the samples showed the same peaks as the MSO2 standard with similar peak intensities. It was pointed out that even the relative peak intensities of the standard injected at two different times varied. HED concluded that, with the 2 dimensional TLC analyses submitted in the original report and the additional mass spec information, the identity of MSO2 as one of the metabolites found in sugar beet top and root has been confirmed.

Stability data under frozen conditions ( 16  C) for sethoxydim residues were also provided by the registrant. Aliquots ( 10 50 g sugar beet top or 25 50 g root) of the 60 day PHI sample from the metabolism study were removed at various intervals during frozen storage, extracted, and analyzed by TLC. TLC profiles showed that levels of sethoxydim, MSO2, 5 OH SO2, and M1 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 25 of 101 and M2 type of metabolites in the top and root remained relatively constant for 20 months. Additional experiments were conducted in which the sugar beet top and root samples after extraction were oxidized and methylated. This process converted sethoxydim residues to DME and DME OH. Amounts of DME and DME OH, expressed in % TRR, were quantitated by TLC.

The 426 day sugar beet top sample and the 393 day sugar beet root sample were also quantitated by GC residue method ( Method 30B) to check the accountability of sethoxydim residues in plant commodities. Method 30B converts sethoxydim residues to DME and DME OH through oxidation and methylation. It accounted for 46% of TRR in sugar beet top and root. Concurrent recoveries ranged 68 102% for sethoxydim and 5 OH MSO2 in sugar beet top and root. The stability data support the validity of the metabolism results obtained from samples that were stored frozen for 18 months.

860.1300 Nature of the Residue  Livestock ( D257559. MEM. wpd)

The nature of the residue in livestock is understood based on acceptable metabolism studies in ruminants ( goat) and poultry ( hens). The residues of concern in animal commodities are the combined residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety.

Ruminants MRID 00153602 ( Summary in MRID 92166046) ( PP# 3F2904, K. Arne, 6/ 26/ 85; Phase V Review, CBRS 17851, L. Cheng, 4/ 4/ 97)

Adequate ruminant metabolism data are available ( Phase V Review, CBRS 17851, L. Cheng, 4/ 4/ 97). A lactating goat was fed 14C ring labeled sethoxydim sulfoxide ( 14C MSO) for 5 consecutive days at 100 ppm in the dry diet. HED notes that this is equivalent to 1.3x of the expected dietary burden of 75 ppm. The residues in milk, liver, and kidney were identified. The residues in muscle and fat were not identified. Analyses of samples were completed in 2 3 months. The study indicated that sethoxydim sulfoxide ( MSO) was oxidized to the corresponding sulfone ( MSO2) followed by desethylation with subsequent methylation at the sulfur atom to form several nor compounds ( nor MS, nor MSO, and nor MSO2). These nor compounds were found in small quantities in milk, liver and kidney. In milk and kidney, the major residues were MSO and MSO2. The major residues in liver were MSO2 and sethoxydim. Sethoxydim was found in kidney and liver, but not in the milk ( D257559, N. Dodd, 1/ 24/ 02).

In the Phase 4 Review ( L. Cheng, 2/ 25/ 91), HED required the registrant to submit a new ruminant metabolism study using the parent, sethoxydim, for feeding. This requirement was later waived by HED ( D165957, D169251 & D170139, C. Swartz, 1/ 24/ 92).

Poultry MRID 00155129 ( Summary in MRID 92166047) ( Phase V Review, CBRS 17851, L. Cheng, 4/ 4/ 97) Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 26 of 101 Adequate poultry metabolism data are available through two poultry metabolism studies. In one poultry metabolism study, laying hens were dosed with 14C sethoxydim sulfoxide ( ring labeled at the C4 and C6 positions) at 50 ppm for 7 days in the diet. HED notes that this dose is equivalent to 4.2x of the theoretical dietary burden of 12 ppm. Residue analyses on eggs and liver were completed in 2 months. The major residues in eggs and liver were MSO and MSO2. In a subsequent submission ( 8 months later) ( RCB # 306, S. Malik, 6/ 23/ 86), frozen samples of liver, muscle, skin, and fat from the above study were analyzed for sethoxydim residues. The major residues in muscle, fat, skin, and liver were MSO and MSO2. M1SO was also found in muscle, fat, and liver.

In a second poultry metabolism study, 10 laying hens were dosed with 14C sethoxydim ( ringlabeled at the C 4 and C 6 position of the ring) at 200 ppm in the diet. Analysis was completed in 2 months. MSO, MSO2, and MS were found in muscle, fat, and liver. The major residues were MSO and MSO2 in muscle and liver, and MSO and MS in fat ( D257559, N. Dodd, 1/ 24/ 02).

In the Phase IV review HED also noted that the registrant failed to characterize radioactive residues in eggs from hens fed with the parent and requested an additional poultry metabolism study. However, HED later waived the requirement for an additional hen metabolism study noting that residues were well characterized and well identified in the two submitted poultry metabolism studies; additional metabolites of toxicological concern would be likely to contain the 2 cyclohexen 1 one moiety, and the analytical method would detect any species containing this moiety ( D165957, D169251 & D170139, C. Swartz, 1/ 24/ 92).

860.1300 Nature of the Residue  Water The Metabolism Assessment Review Committee ( MARC) discussed residues of the herbicide sethoxydim in water on 5/ 14/ 98. The likely degradates in soil and water were described at the meeting by Jim Breithaupt, EFED. The predominant degradates in soil are the sulfoxide and sulfone derivatives of the parent ( MSO, MSO2). Those degradates are expected to be found in water along with M1S ( loss of ethoxy group on imino nitrogen) and M2S ( formation of oxazole ring). Toxicology data for the four degradates expected in water do not appear to be available. In the absence of such data, the MARC concluded that these degradates should be considered as having comparable toxicity as the parent. Therefore, for risk assessment purposes, the residues in water are the " total sethoxydim residues" in water ( i. e., parent plus degradates). ( Metabolism Assessment Review Committee meeting on 5/ 14/ 98; R. Loranger memo dated 5/ 27/ 98).

860.1340 Residue Analytical Methods ( D257559. MEM. wpd)

BASF Wyandotte Corporation's ( BWC's) Methods No. 30, 30G, 30H and A9003 are adequate analytical methods for data collection and/ or enforcement of tolerances for residues of sethoxydim and its metabolites in or on plant and animal commodities. Summaries of these methods are Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 27 of 101 provided below.

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 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 and acidic back extraction and then partitioned with methylene chloride. Sethoxydim and its metabolites are oxidized to 3[ 2 ( ethoxysulfonyl) propyl] pentanedioic acid and 3[ 2( ethoxysulfonyl) propyl] 3 hydroxypentanedioic acid and then derivatized to DME and DME OH, respectively. The derivatives are partitioned into methylene chloride and cleaned up by silica gel column chromatography. Some samples require an additional HPLC cleanup. DME and DME OH are determined by GLC with flame photometric detection.

Successful EPA petition method validation trials were conducted for Method 30 on soybeans, beef liver, and milk. In the soybean validation trial, EPA obtained recoveries of 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. Two trials were conducted with beef liver and milk. In one trial, EPA obtained recoveries of 92 95% for sethoxydim and M2SO2, each added to duplicate beef liver samples at 0.2 ppm. Recoveries of MSO2 and 5 OH MSO2, each added to duplicate milk samples at 0.05 ppm, were 72 90% ( PP# 2F2670, K. Kissler, 4/ 1/ 83; D257559, N. Dodd, 1/ 24/ 02). In the other trial, Method 30 was determined to be adequate for residue determination of the metabolites M1SO, nor MSO, and nor MSO2 in milk and livestock tissue. Recoveries of the metabolites ranged from 70 to 107% in milk fortified at levels of 0.05 and 0.1 ppm and from 68 to 100% in beef liver fortified at levels of 0.2 and 0.4 ppm ( PP# 3F2904, 11/ 2/ 88, S. Malak). The results were forwarded to FDA for updating the Method I entry in PAM II ( S. Malak, 11/ 7/ 88).

Method 30G and 30H BWC's Method 30G " Addendum to BWC Agricultural Chemicals Method No. 30 for the Determination of BAS 9052H and its Metabolite Residues in Alfalfa Forage and Soybean Forage" and Method 30H " Addendum to BWC Agricultural Chemicals Method No. 30 for the Determination of BAS 9052H and its Metabolite Residues in Alfalfa Hay and Soybean Hay" are common moiety methods and are essentially similar to Method No. 30, except that both methods skip the methylene chloride partition step just before oxidation. Method 30G is designed for determination of residues of sethoxydim and its metabolites in succulent commodities, forages, fruits and vegetables; the limit of detection is 0.05 ppm sethoxydim equivalents ( 0.1 ppm for citrus process products, succulent beans and peas). Method 30H is designed for analysis of residues of sethoxydim and its metabolites in dry commodities, hay, flax products, dry grape Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 28 of 101 products ( raisins, raisin waste and dry pomace), dry potato process products and sugar beet tops; the limit of detection is 0.05 ppm sethoxydim equivalents ( 0.1 ppm for grape and potato process products). Methods 30G and 30H were submitted for publication in PAM II ( see letter from M Bradley, EPA to A. Marcotte, FDA, 5/ 4/ 90) as Method A and B, respectively; however, they have not as of this time appeared in PAM II.

Method A9003 BWC's Method A9003 is chemically similar to BASF Methods 30G and 30H; the primary innovation in Method A9003 is the transfer of the analyte from an aqueous solution into activated charcoal prior to methylation. Briefly, sethoxydim and its metabolites are extracted from the matrix with an isopropanol/ water mixture. A calcium hydroxide precipitation step follows. The extract is then oxidized using hydrogen peroxide. After phase separation, the acids are isolated from the aqueous phase by charcoal treatment and subsequently converted to their dimethyl esters. Sample purification is accomplished by silica gel column chromatography and C 18 solid phase extraction, if necessary. Final determination is made by gas chromatography with sulfur detection. Alfalfa hay, spinach, poultry meat, corn grain, tomato, and apple were used in the validation. The method was not successful with soybeans or most other oily matrices. Samples were fortified on the day of the analysis with metabolites MSO and 5 OH MSO2 at levels ranging from 0.05 to 50 ppm. Overall, mean recoveries were 83% for MSO and 81% for 5 OH MSO 2. Since the method was not considered acceptable for soybeans, the overall mean recoveries do not include percent recoveries for soybeans. The limit of quantitation for spinach, poultry meat, corn grain, tomato, and apple was 0.05 ppm for each analyte. The limit of quantitation for alfalfa hay was 0.5 ppm for each analyte. HED noted that Method A9003 would be sent to FDA for inclusion in Pesticide Analytical Manual ( PAM) II as a lettered method ( D210060, D210062, D208310, & D208312, M. I. Rodriguez, 7/ 24/ 95).

Method 278 It should be noted that in the crop field trials for mint, samples were analyzed by BASF Method 278, which is a slightly modified version of BASF Method 30G and 30H ( D172349, W. D. Wassell, 2/ 11/ 92  file R066020). In this method, the samples are soaked in water and extracted with isopropanol. The extract is precipitated and oxidized as in Methods 30G and 30H. A modification includes an isolation of the residues utilizing charcoal adsorption.

860.1360 Multiresidue Methods Multiresidue data for sethoxydim, sethoxydim sulfoxide ( MSO), and 5 hydroxy sethoxydim sulfone ( 5 OH MSO2) were submitted by the registrant in MRID 4198701. Only protocols C, D, and E were tested since protocols A and B were not applicable. Under current guidelines, protocol G is also not applicable. Sethoxydim and sethoxydim sulfoxide ( MSO) chromatographed through Protocol C but did not elute through Florisil; therefore, these analytes could not be recovered through Protocols D and/ or E. On the other hand, 5 hydroxy sethoxydim sulfone ( 5 OH MSO2) did not chromatograph through Protocol C. The registrant concluded that sethoxydim and its metabolites are not amenable to the multiresidue test procedures defined in PAM I. The results were forwarded to FDA for evaluation and inclusion in PAM, Vol I, Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 29 of 101 Appendix I. ( PP# 0F3855 and 0E3900, M. J. Nelson, 10/ 9/ 91).

The FDA PESTDATA database dated 10/ 99 ( PAM Volume I, Appendix I) indicates that sethoxydim and sethoxydim sulfone are not recovered through protocol E ( Section 303) or protocol F ( Section 304).

860.1380 Storage Stability Plant Commodities ( D256970. DER. wpd)

The Phase IV review, HED indicated that data were available to demonstrate the stability of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety in several commodities for 14 to 60 months of frozen storage. However, the Sethoxydim Phase IV review was issued prior to the investigation of the validity of data generated by Craven Laboratories. As a result of the Craven investigation, HED assessed the impact Craven data had on sethoxydim registrations. With respect to storage stability data, 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 ( D165411, L. Cheng, 9/ 23/ 91). For soybean seeds, the data indicate that residues of parent, MSO2, M2SO2, and 5 OH MSO2 are stable for only up to 24 months ( D256970, N. Dodd, 8/ 9/ 01).

In response to a Data Call In ( DCI) regarding the replacement of the data generated by Craven Laboratories, the registrant submitted freezer storage stability data for sethoxydim and its metabolites in 13 representative fruit and vegetable crops. In these studies ( MRIDs 43801401, 43801402, 43801403, 43801404 and 438014015), untreated control samples of corn grain, corn forage, cherry, orange, strawberry, potato, onion, lettuce, apple, succulent bean, and dry bean from previous field trials and those of tomatoes and cucumbers purchased from local supermarkets were fortified with MSO and with MSO2. Initial screening of the control samples indicated that most matrices were free of any interfering residues with residues < 0.01 ppm ( cherries, oranges, strawberries, potatoes, lettuce, tomatoes, and apples). The remaining matrices ( corn grain, corn forage, onion, cucumber, succulent bean, and dry bean) bore 0.05 ppm or less contaminants which appeared at similar retention times on gas chromatography as DME and DME OH. These levels were considered insignificant when compared to the 1 10 ppm fortification levels.

Samples were fortified with a solution containing either 1, 2, 3, or 10 ppm of MSO and 1, 2, 3, or 10 ppm of 5 OH MSO2. The fortified samples and the large composite samples of control materials were then transferred to a freezer where they were kept at  5  C until analysis. On the day of each analysis, two aliquots of stored fortification samples and two control samples were removed from the freezer for analysis. One or two aliquots of the control material were weighed out and used for procedural fortifications. Each of these two procedural fortification ( concurrent recovery) samples was fortified with 1.0 ( corn grain, corn forage, cherries, oranges, potatoes, onions, lettuce, cucumbers, and apples), 2.0 ( strawberries), 3.0 ( tomatoes), or 10.0 ( succulent Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 30 of 101 beans and dry beans) ppm each of MSO and 5 OH MSO2.

The corn grain and dry bean were analyzed by Method 30. The remaining crop matrices were analyzed by Method 30B. The limit of quantitation for Method 30 and 30B for all thirteen crop matrices was given as 0.05 ppm per metabolite. For MSO, recoveries of the stored samples from all crop matrices were not significantly different from those fortified on the days of analysis throughout the test period. For 5 HO MSO2, acceptable recoveries were obtained in most crop matrices throughout the test period except in cherries, strawberries, potatoes, tomatoes, and succulent bean.

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. ( D219970, L. Cheng, 4/ 9/ 96).

HED indicated that the replacement storage stability studies did not include an oil seed ( soybean or nut) crop. However, non Craven storage stability data for soybeans was submitted previously and demonstrates stability of sethoxydim and it's metabolites for up to 24 months.

Animal commodities A study to document the stability of sethoxydim metabolites ( MSO, non hydroxylated, and 5 OHMSO2 hydroxylated) in livestock matrices under frozen conditions was conducted by the registrant ( MRID 43223401). In this study, whole bovine milk, chicken eggs, ground beef ( 30% fat), chicken breasts with bone and skin, beef liver, and beef kidney were purchased from a local grocer. No further sample preparation was necessary for the milk and ground beef. The white and yolk of eggs were homogenized; the chicken breasts were deboned, cut into strips ( with skin), and ground up in a meat grinder. The beef kidney and liver were cut into strips and fed through the meat grinder. All samples were prepared after thawing but while still cold. Aliquots of each matrix were selected as control, or fortified with ( nominally) 1 ppm of MSO or 1 ppm 5 OHMSO 2 as procedural and storage samples. The samples were kept at  5  C or colder and analyzed at intervals of 0, 3, 6, 12, 18, and 25 months ( D203246, L. Cheng, 8/ 15/ 94).

Samples were agitated with methanol in a blender and then concentrated to near dryness. Calcium hydroxide was added ( yielding precipitation) and the mixture was filtered. The filtrate was acidified, extracted with dichloromethane and evaporated to dryness. The residues were oxidized with alkaline hydrogen peroxide and any excess oxidizing agent was quenched enzymatically. The oxidized products were converted to methyl esters with sulfuric acid and methanol, and excess acid was quenched with saturated sodium bicarbonate. The two esters ( DME and OH DME) were extracted into dichloromethane. All samples were purified through a silica gel and/ or C 18 solid phase column before GC analysis ( FPD in the sulfur mode). The limit of quantitation of all analyses was 0.05 ppm for either metabolite. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 31 of 101 Percent recoveries of MSO and 5 OH MSO2 in all the matrices tested were generally in the 80 90% range. HED concluded that residues of sethoxydim, hydroxylated and non hydroxylated are stable in livestock commodities under frozen conditions for 26 months ( D203246, L. Cheng, 8/ 15/ 94).

860.1400 Water, Fish, and Irrigated Crops Sethoxydim is not presently registered for direct use on water and aquatic food and feed crops; therefore, no residue chemistry data are required under these guideline topics.

860.1460 Food Handling Sethoxydim is not presently registered for use in food handling establishments; therefore, no residue chemistry data are required under this guideline topic.

860.1480 Meat, Milk, Poultry, and Eggs ( D257559. MEM. wpd)

Feeding studies with lactating dairy cows ( administered 0.60 or 50.0 ppm sethoxydim for 30 days) and laying hens ( fed 1, 10, or 100 ppm sethoxydim for 30 days) were submitted in connection with PP# 0G2396 ( E. Zager, 12/ 4/ 80). However, because the dose levels in the cattle feeding study were less than the computed dietary burden for cattle ( see Table 7), data from a 75 ppm goat feeding study were used for the analysis that follows.

Dietary burdens were calculated assuming reasonably balanced diets comprised of roughage, protein concentrate, and carbohydrate concentrate for cattle, and protein concentrate and carbohydrate concentrate for swine and poultry. These diets and their resulting dietary burdens are presented in Tables 7 and 8.

Table 7. Calculated theoretical dietary burden of sethoxydim for beef and dairy cattle.

Feedstuff Tolerance level ( ppm) % Dry Matter Beef & Dairy Cattle % of Diet Dietary Burden ( ppm)

Alfalfa, forage 40 35 50 57 Sunflower, meal 20 92 15 3.3 Beet, sugar, molasses 10 75 10 1.3 Potato, processed waste 8 15 25 13.3 Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 Table 7. Calculated theoretical dietary burden of sethoxydim for beef and dairy cattle.

Feedstuff Tolerance level ( ppm) % Dry Matter Beef & Dairy Cattle % of Diet Dietary Burden ( ppm)

32 of 101 Total for diet 100 74.9 Table 8. Calculated theoretical dietary burden of sethoxydim for poultry and swine Feedstuff Tolerance Level ( ppm) Poultry Swine % Diet Burden ( ppm) % Diet Burden ( ppm)

canola meal 40 15 6 15 6 Corn, field, grain 0.5 85 0.43 85 0.43 Total 100 6.4 100 6.4 In lactating goats fed hay containing 75 ppm sethoxydim for 28 days ( PP# 8F3640/ 8H5557, H. Fonouni, 11/ 4/ 88; PP# 4F04344, D208310, M. Rodriguez, 7/ 24/ 95), residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety were < 0.05 ppm in muscle and fat, < 0.44 ppm in kidney, 0.14 ppm in liver, and < 0.01 0.18 ppm in milk. The maximum residue levels measured in each tissue are summarized below in Table 9 and used to computed the maximum potential sethoxydim residue level in each tissue assuming a dietary burden of 75 ppm for cattle.

Table 9. Maximum potential sethoxydim residue levels based on lactating goat feeding study.

Matrix Max sethoxydim residue at 75 ppm dosing level T/ Fa Dietary Burden ( ppm) Max potential sethoxydim level ( ppm) b Muscle < 0.05 0.000667 75 < 0.05 Fat < 0.05 0.000667 75 < 0.05 Kidney < 0.44 0.00587 75 < 0.44 Liver 0.14 0.00187 75 0.14 Milk 0.18 0.00240 75 0.18 a Tissue to feed ratio calculated as maximum sethoxydim residue level in the indicated tissue divided by the 75 ppm dosing level. b Determined by multiplying the T/ F value and the dietary burden.

In the poultry feeding study, no detectable residues were reported for muscle samples from the 1.0 or 10.0 ppm dosage level. Residue levels of < 0.05 0.19 ppm were found in muscle tissues from the 100 ppm level. In poultry liver, residues of < 0.05 0.34 ppm and 0.23 0.47 ppm were Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 33 of 101 found in samples from the 10 and 100 ppm feeding levels, respectively. In eggs, residue values of < 0.05 0.34 were reported for the 10 ppm feeding level, and < 0.05 1.88 ppm for the 100 ppm feeding level ( PP# 9F3806, L. Rodriguez, 2/ 27/ 90; PP# 0G2396, E. Zager, 12/ 4/ 80).

Table 10. Maximum potential sethoxydim residue levels based on poultry feeding study.

Matrix Max sethoxydim residue at 10 ppm dosing level T/ Fa Dietary Burden ( ppm) Max potential sethoxydim level ( ppm) b Muscle 0.11 0.011 6.4 0.07 Liver 0.17 0.017 6.4 0.11 Eggs 0.34 0.034 6.4 0.22 a Tissue to feed ratio calculated as maximum sethoxydim residue level in the indicated tissue divided by the 10 ppm dosing level. b Determined by multiplying the T/ F value and the dietary burden.

Based on the feeding study results and the dietary burden calculations, secondary residues in livestock commodities may be expected as a result of livestock ingesting feedstuffs derived from crops which may be treated with sethoxydim. 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, and sheep at 1.0 ppm ( 2.0 ppm in meat byproducts of poultry); eggs at 2.0 ppm, and milk at 0.5 ppm. The existing sethoxydim permanent tolerances on livestock commodities are adequate to cover the maximum potential sethoxydim residue levels presented in Tables 9 and 10.

860.1500 Crop Field Trials In the Phase IV review for sethoxydim ( L. Cheng, 2/ 25/ 91), HED requested magnitude of residue studies for various crops to fulfill data gaps identified during review. Subsequent to the completion of the Phase IV review, the validity of certain field studies was questioned because residue samples from those studies had been analyzed in a particular contract laboratory, Craven Labs ( D165411, L. Cheng, 9/ 23/ 91). As a result, the Agency issued a DCI to replace residue chemistry data generated by Craven Labs for alfalfa hay, artichoke, succulent beans, dry beans, broccoli, cabbage, mustard greens, cotton, flax, peppers, tomatoes, grapes, lentils, peanuts, succulent peas, dry peas, potatoes, raspberry, soybeans, strawberry and sugar beets. Only data not generated by Craven Laboratories are included in the following summaries of crop field trials.

Alfalfa Two studies were originally submitted ( MRIDs 001155129 and 40515801) to provide residue chemistry data to support registration of sethoxydim for use on alfalfa. As some of the alfalfa hay Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 34 of 101 samples were analyzed by Craven Laboratories, HED requested replacement data reflecting maximum label use pattern from CA/ ID/ OR/ WA, IA/ MN/ NE/ WI, and NY/ OH/ PA. No new data for alfalfa forage were requested because the samples were not analyzed by Craven Labs ( D165411, L. Cheng, 9/ 23/ 91). In response to the data request, the Registrant submitted another study ( MRID 41970901) which analyzed both alfalfa hay and forage samples. The new forage data, however, were not submitted by the Registrant with the intention of replacing the previously submitted data. Summaries of the submitted data are provided below.

Forage MRIDs 00155129 and 40515801 ( D209952, L. Cheng, 1/ 19/ 95)

In support of a tolerance of 40 ppm on alfalfa forage ( 7 day PHI), the registrant submitted residue data in MRID 00155129 ( submission dated 12/ 85) and 40515801 ( 6/ 87). HED noted that residue data for alfalfa forage had not been generated by Craven, so no replacement data were needed ( D165411, L. Cheng, 9/ 23/ 91).

According to a memo by L. Cheng ( D209952, 1/ 19/ 95) the field trials described in MRID 00155129 were conducted in CA, AZ, and NM. In these trials, alfalfa plants were treated with sethoxydim at 1 x 0.5 lb ai/ A + 2 x 0.3 lb ai/ A or 3 x 0.5 lb ai/ A by ground application. Information on spray volumes was not provided in the report. Forage was sampled at 6 to 18 days after the last treatment. Analytical Method 30G ( Determination of BAS 9052 H and Its Metabolite Residues in Alfalfa Forage and Soybean Forage) was used for residue analysis and its limit of quantitation was 0.5 ppm sethoxydim equivalent for each analyte. Recoveries were 73 128% for MSO ( parent sulfoxide) when fortified at 0.5, 1.0, 5.0, 10.0, 15.0, 20.0 or 30.0 ppm, and 66 112% for 5 OH MSO2 ( parent sulfone hydroxylated at C 5 position) when fortified at the same levels. Control samples contained 0.13 ppm or less MSO (< 0.5 ppm sethoxydim) or 5 OHMSO2 equivalents. Combined residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety ranged from < 1.5 ppm to 20.7 ppm.

The study described in MRID 40515801 was a side by side aerial versus ground application experiment conducted in CA at several locations. Identical treatment rates and virtually identical pre harvest intervals were employed. Plants were treated with sethoxydim at 1 x 0.3 or 0.5 lb ai/ A. Samples of forage were collected at 6 10 days and 20 or 22 days later, and samples of hay were collected 19 28 days later. Residue levels from air applications ( 1.7 18.5 ppm for forage and 3.8 10.8 ppm for hay) were equal or less than those from ground applications ( 1.6 32.8 ppm for forage and 4.1 30.9 ppm for hay). The available residue data are adequate to support the current tolerance of 40 ppm on alfalfa forage.

Hay MRID 41970901 ( D200363, L. Cheng, 8/ 22/ 94)

In D165411 ( L. Cheng, 9/ 23/ 91), HED indicated that some of the alfalfa hay residue data submitted in MRID 1155129 had been generated by Craven Laboratories. The residue data not generated by Craven Laboratories were from crop field trials conducted at less than the maximum application rate. HED requested that replacement data reflecting maximum label use pattern from Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 35 of 101 CA/ ID/ OR/ WA, IA/ MN/ NE/ WI, and NY/ OH/ PA be submitted ( D165411, L. Cheng, 9/ 23/ 91).

In response to the Craven DCI, the registrant provided residue data from trials conducted in CA, IA, ID, KS, MI, MN, ND, NE, NY, SD, and WI. These data were also provided to support a label amendment requesting the PHI to be revised to 14 days. Alfalfa received three applications of sethoxydim at 0.5, 0.5 and 0.3 lb ai/ A at intervals varying from roughly 4 to 8 weeks. Applications were made by ground equipment in a spray volume of 15 20 gallons/ A. Samples of forage and hay were collected after each treatment at PHIs of 12 15 days; one cutting had a PHI of 7 days. Forage samples were frozen immediately after harvest. Forage and hay samples were homogenized and stored frozen until shipment to the laboratory for analysis.

The analytical methods used were modified versions of Method 30G ( for alfalfa and soybean forage) and Method 30H ( for alfalfa and soybean hay). The limit of quantitation was 0.5 ppm for DME or DME OH, or 1.0 ppm for the total residue. For recoveries, forage and hay samples were fortified with metabolite MSO or MSO2 at 0.5 15.0 ppm for forage and at 0.5 40 ppm for hay. Better individual recoveries were obtained in forage than in hay. Average recoveries were 87 ± 21% ( N= 36) for forage and 80 ± 24% ( N= 48) for hay.

Residue samples were stored for ca 12 18 months before analysis. HED concluded that data submitted for corn forage and dry beans were adequate to show the stability of sethoxydim residues in alfalfa forage and hay under frozen storage conditions for 27 months.

Residues resulting from three treatments of alfalfa with sethoxydim at 0.5 + 0.5 + 0.3 lb ai/ A and a PHI of 12 15 days ranged up to 15 ppm in forage and 31 ppm in hay. The available residue data are adequate to support the current tolerance of 40 ppm on alfalfa hay.

Almonds, hulls MRID 41428501 ( PP0F3855, M. J. Nelson, 2/ 7/ 91)

Six field trials were conducted in CA to provide residue chemistry data to support registration of sethoxydim for use on almonds. Multiple applications of Poast ® Herbicide were made at 1x or 2x the maximum recommended label rate, for a total of 1.5  4 lb ai/ A/ season. PHIs ranged from 9 to 18 days. Samples were harvested at normal maturity and stored frozen for up to 48 months prior to analysis by Method 30H. Control samples ( almonds, pecans and walnuts) were fortified with sethoxydim, MSO and 5 OH MSO2 at levels ranging from 0.1 ppm to 1.5 ppm. Recoveries of sethoxydim ranged from 68 to 120% with an average of 92%; MSO recoveries ranged from 72 110% with an average of 89%; while for 5 OH MSO2 recoveries ranged from 69 to 110% with an average of 83%.

Almonds were stored for 24 months ( 4 field trials), 35 months ( 1 field trial), and 48 months ( 1 field trial). The registrant referenced storage stability data from other crops ( strawberries, cherries, soybeans, peanut hay, and succulent peas) that indicated stability for sethoxydim and its metabolites for up to a 60 month storage period. HED determined that only the data for soybean seeds were not generated by Craven, and these data only support storage for up to 24 months ( D198048, L. Cheng, 4/ 26/ 94). However, HED concluded that the stability of sethoxydim and Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 36 of 101 metabolites in almonds for the storage duration is adequately supported by the Craven replacement storage stability data that shows stability in various frozen commodities for 3 5 years ( D256970, N. Dodd, 8/ 9/ 01).

Non detectable residues (< 0.1 ppm) were reported for DME OH in all almond hull samples, but residues of DME ranged from < 0.1 ppm to 0.96 ppm. The available residue data are adequate to support the established tolerance level of 2.0 ppm for almond, hulls.

Apricot MRID 41236404 ( PP9F3804/ PP9H5589, S. Inasi, 8/ 8/ 90)

Only one apricot sample was analyzed; the total residue was < 0.1 ppm. HED has determined that the residue data from the analysis of peaches ( 13 samples) can be translated to apricots. Residue data for peaches are provided under the Peaches section of this memo.

Artichoke, globe MRID 43973101 ( D238439, W. Cutchin, 4/ 8/ 98; D225427, W. Cutchin, 6/ 12/ 98 The original artichoke field trial data submitted were generated by Craven Laboratories. The data were replaced with two globe artichoke field trials conducted in California ( MRID 43973101). Field trial residue results ranged from 0.31  4.3 ppm. These data support the established tolerance of 5.0 ppm for sethoxydim on globe artichokes. It should be noted that the tolerance for globe artichoke is a tolerance with regional registration listed under 40 CFR § 180.412 ( c).

Asparagus MRID 42487401 & 42487402 ( D183351, D. Davis, 12/ 4/ 92)

Two studies were submitted ( MRID 42487401 and 42487402) to provide residue chemistry data to support registration of sethoxydim for use on asparagus. MRID 42487401 provides data for eight field trials conducted in five states ( CA, WA, MI, IL, NJ) and MRID 42487402 provides data for two field trials conducted in two states ( MI and AZ). HED determined that the number, geographical representation, and application pattern of the field trials are adequate. Additionally, HED determined that storage stability data from soybean forage and succulent legumes studies are translatable to asparagus and are adequate to demonstrate the stability of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety on asparagus for the interval that the crop field residue samples were stored. The results indicate maximum combined residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety are 2.14 ppm for MRID 42487401 and 3.5 ppm for MRID 42487402. These data are adequate to support the established tolerance level of 4.0 ppm for sethoxydim on asparagus.

Bean, dry, seed MRID 43801413 ( D237724, L. Cheng, 7/ 28/ 97) Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 37 of 101 Replacement field trials to replace data generated by Craven Laboratories on dry beans were conducted in CA( 2), CO, ID, MI, NE, and ND. Beans were harvested 30 days after the second of two applications of the 1.5 lb/ gal EC formulation, the first at 0.28 lb ai/ A and the second 14 days later at 0.47 lb ai/ A ( 1x the maximum registered seasonal rate). Broadcast applications were made in 5 gal/ A using ground equipment.

Samples of beans were bagged and stored frozen for a maximum of 13 months prior to analysis using GC/ FPD Method 30. HED noted that storage stability data on 13 matrices submitted with the residue data on tomatoes, broccoli, mustard greens, and cabbage ( D219970, 4/ 9/ 96, L. Cheng) indicate that sethoxydim and metabolites are stable for 3 5 years. Thus, adequate supporting storage stability data are available to cover the storage intervals reflected in the field trials.

Samples were analyzed using Method 30. Concurrent recoveries were adequate; recoveries ranged from 68 to 95% for MSO and from 80 to 122% for 5 OH MSO2 in dry beans. Apparent combined residues were less than the limit of quantitation (< 0.1 ppm) in/ on one or two samples of untreated dry beans from each trial.

HED concluded that the dry bean field trials were acceptable. The trials were conducted in the states specified by the DCI. Residues in the dry beans ranged from 4.41 to 13.3 ppm. These data are adequate to support the established tolerance level of 20.0 ppm for sethoxydim on bean, dry, seed.

Bean, succulent MRID 43801411( D237724, L. Cheng, 7/ 28/ 97)

Studies were conducted to replace existing succulent bean residue data generated by Craven Laboratories. Field trials on snap beans and lima beans were conducted in CA( 2), FL, MI, NJ, and NC, and two trials on cow peas were conducted in FL and NC. Bean pods were harvested 15 days after the second of two applications of the 1.5 lb/ gal EC formulation, the first at 0.28 lb ai/ A and the second 14 days later at 0.47 lb ai/ A ( 1x the maximum registered seasonal rate). Broadcast applications were made in 5 gal/ A using ground equipment.

Samples of bean pods were bagged and stored frozen for a maximum of 15 months prior to analysis using GC/ FPD method 30G. As noted above, adequate supporting storage stability data were available to cover the storage intervals reflected in the field trials. Concurrent recoveries were adequate.

Residues were detected in snap bean pods at 0.52 7.49 ppm, in lima bean pods at 2.76 5.08 ppm, and in cow pea pods at 2.41 13.0 ppm. HED concluded that the succulent bean field trials were acceptable. The trials were conducted in the states specified by the DCI. These data indicate that the established tolerance of 15 ppm for succulent bean is adequate.

Bean, forage and hay MRID 43801413 and 43801411 ( D237724, L. Cheng, 7/ 28/ 97) Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 38 of 101 In conjunction with field trials on succulent and dry beans, the registrant provided data on bean vines ( forage) and hay. Vine and hay samples were harvested 15 30 days following two applications of the 1.5 lb/ gal EC formulation at 0.28 and 0.47 lb ai/ A. The application rates and PHIs all reflect the current label rates for these crops.

Sethoxydim residues in legume forage samples were analyzed using BASF GC/ FPD Methods 30G and 30H, following up to 15 months in frozen storage. As noted above, adequate supporting storage stability data were available to cover the storage intervals reflected in the field trials. Concurrent recoveries were adequate.

Combined residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety ranged from 1 ppm to 13 ppm for bean forage and 1 ppm to 27 ppm for bean hay. HED concluded that the bean foliage field trials were acceptable. The trials were conducted in the states specified by the DCI. These data indicate that the established tolerances of 15 and 50 ppm for bean forage and hay are adequate.

Beet, Garden No MRID number ( D225427; W. Cutchin; 6/ 12/ 98)

No data on garden beets were submitted by the Registrant. HED determined that since sugar beets and garden beets are in the same crop subgroup, data can be translated from sugar beets to garden beets, provided the PHI is increased to 60 days. As the registrant has complied with this condition, HED concludes that the established tolerance of 1.0 ppm is adequate for beet, garden, roots.

Beet, sugar ( roots and tops) MRID 155129 and MRID 40639101 ( Summary in MRID 92166067) ( L. Cheng, 2/ 25/ 91) MRID 40639102 ( D185410 M. I. Rodríguez; 8/ 25/ 93)

According to the Phase IV Review, field trials ( MRID 155129 and 40639101) were conducted in major sugar beet growing areas with 2 x 0.5 lb ai/ A ( label maximum) treatments by ground and aerial equipment. At PHIs approximating 100 days ( the previous label PHI), roots contained < 0.1 ppm residues and tops contained < 3 ppm residues ( L. Cheng, 2/ 25/ 91). It was determined that a portion of the sugar beet top data was generated by Craven Laboratories ( D165411, L. Cheng, 9/ 23/ 91); however, the data for the sugar beet top samples collected at a PHI of 60 days ( the current label PHI) were not analyzed by Craven Laboratories ( W. Wassel; 8/ 6/ 93). As the Registrant submitted an amendment to decrease the pre harvest interval from an interval of 100 days to an interval of 60 days, no further sugarbeet top data were required.

The non Craven residue data for sugar beet tops reflecting a PHI of 60 days and the maximum application rate of 1.0 lbs ai/ A ( two applications of 0.5 lbs ai/ A, both ground and aerial application trials) were available from CA ( 10 trials), ND ( 1 trial), MN ( 1 trial), ID ( 1 trial) and MT ( 1 trial). In these field trials, the highest residue level was approximately 0.73 ppm with preharvest intervals ranging from 38 to 69 days. The established tolerance of 3.0 ppm for the Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 39 of 101 residues of sethoxydim and its metabolites in or on sugar beet tops is adequately supported by residue data.

Since the Phase IV review, the registrant also submitted an amendment to increase the tolerance for sugar beet roots from 0.1 to 1.0 ppm. According to D185410 ( M. I. Rodríguez; 8/ 25/ 03), two sets of data ( presumably in MRID 40639101 and 40639102) were available to support these changes. In one set of data, three sugar beet root samples from 17 field trials in 9 states were over the limit of detection ( 0.05 ppm) at a 60 day PHI. These residues ( 0.07, 0.20, and 0.28 ppm) were detected in samples which received two applications at 0.5 lb ai/ A application ( total of 1.0 lb ai/ A). The other set of data ( 14 trials in 5 states) show that the maximum level detected in roots was 0.40 ppm at a 60 day PHI. These residues were detected in samples which also received two applications at 0.5 lb ai/ A application ( total of 1.0 lb ai/ A). The established tolerance of 1.0 ppm for the residues of sethoxydim and its metabolites in or on sugar beet roots is adequately supported by residue data.

Blueberry MRID 40492604 ( Summary in 92166073)

Nine field trials were conducted at the maximum label rate and minimum PHI in the following states: GA ( Region 2), IL ( Region 5), ME ( Region 1), MI [ 3 trials] ( Region 5), NC ( Region 2), NJ ( Region 2), and WA ( Region 12). The number and distribution of blueberry field trials is adequate to satisfy reregistration data requirements. Sethoxydim was applied 2 times at a rate of 0.5 lbs/ A/ application, with a minimum retreatment interval ( RTI) of 9 days, and a PHI of 29 33 days. The maximum frozen storage interval (<  5  C) was 30 months. This interval was supported by strawberry storage stability data showing no significant loss of residues in samples held at <  5  C for up to 31 months. Fortification/ recovery experiments were run at levels ranging from 0.05 to 15.0 ppm. Control blueberry samples were fortified with sethoxydim and/ or metabolites MSO and 5 OH MSO2 and analyzed concurrently with treated samples, using Method 30G. Recoveries ranged from 82 126%. Residue levels in treated blueberry samples ranged from < 0.10  3.4 ppm. These values adequately support the established blueberry tolerance level of 4.0 ppm.

Caneberry subgroup 13A MRID 00157187 ( Summary in 92166066) ( L. Cheng, 2/ 25/ 91) MRID 43972701 ( D238439, W. Cutchin, 4/ 8/ 98; D225427, W. Cutchin, 6/ 12/ 98)

Crop field trials were submitted for raspberries, a representative commodity of the caneberry subgroup. The trials were conducted in MI, OR, WA, CA, NJ, and NY ( MRID 00157187) Sethoxydim was applied 2 or 3 times at a rate of 0.5 lb ai/ A/ application. The samples from MI, OR, WA, and CA were collected at a PHI of 45 days and the samples from NJ and NY were collected at a PHI of 21 to 31 days. The Phase IV review indicates that all residue values were below the established tolerance of 5 ppm. In D165411 ( L. Cheng, 9/ 23/ 91), HED noted that even though the tolerance was set at 5 ppm, the residues resulting from 2 x 0.5 lb ai/ A and a PHI of 45 days were generally < 0.1 ppm. It was determined that Craven Laboratory analyzed the samples Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 40 of 101 from the MI, OR, WA, and CA test sites ( D165411, L. Cheng, 9/ 23/ 91). HED concluded that the NJ and NY data were adequate to support the raspberry tolerance in the interim; however, raspberry residue data from WA and OR may be required to support the established tolerance.

To replace the Craven data, two trials ( OR and WA) on raspberries conducted in 1996 were submitted ( MRID 43972701). In the OR study, sethoxydim was applied twice at approximately 0.5 lb ai/ A and samples taken at a 45 day PHI. In the WA study, sethoxydim was applied twice at approximately 1.0 lb ai/ A ( 2x the maximum label rate) and samples taken at a 39 day PHI.

The raspberry samples from MRID 43972701 were analyzed using BASF Method 30. Recoveries from samples fortified with DME and DME OH at 0.042 to 0.86 ppm and concurrently analyzed with the field samples ranged from 85 122% ( n = 20). The highest sethoxydim residue found was from a sample from the WA study which contained 4.3 ppm total residues as sethoxydim. The performing laboratory, Analytical Labs., Dept. of Food Science, Cornell University, included sample chromatograms and calibration curves ( D238439; W. Cutchin; 4/ 8/ 98). These data are adequate to support the established sethoxydim tolerance level of 5.0 ppm for crop subgroup 13A ( caneberries).

Canola, rapeseed MRID 42074201 ( D171714, D171716, D171724, B. Schneider, 9/ 21/ 92) Eight field trials were conducted in the following six states: ID, MT, ND, OH, OR, and TN. It was noted that these states represent > 60 % of the total U. S. canola production ( D171714, D171716, D171724, B. A. Schneider, 6/ 4/ 92). HED concluded that geographical representation for the submitted field trials for canola is adequate. Sethoxydim ( Poast ® Herbicide) was applied postemergent at two applications at 14 19 day intervals using the maximum label rate at 0.5 lb ai/ A ( 1X) with PHI's ranging from 59 61 days. These treatments were applied as a broadcast ground application directly to the emerged weeds ( 4 6 inches tall).

Samples of the forage and seed were stored frozen at <  5  C until further analysis; samples were analyzed 19 months after initial storage following harvest. No storage stability data were submitted for this crop; however, HED concluded that storage stability data developed for soybean seed were adequate and translatable to canola.

Slight modifications of the BASF Method 30 and BASF Method 30G were used for the determination of sethoxydim in canola seeds and forage, respectively. No samples were analyzed by the Craven Laboratories. The limit of quantitation was 0.05 ppm of sethoxydim equivalents for DME or DME OH, or 1.0 ppm for the total residue. Control samples were fortified with the metabolite MSO and 5 OH MSO2. The canola forage samples showed recoveries of MSO ranging from 61 to 115% with an average of 91 ± 12%; while for 5 OH MSO2 ranged from 65 to 114% with an average of 96 ± 13%. The canola seed samples showed recoveries of MSO ranging from 69 to 115% with an average of 94 ± 14.5%; while for 5 OH MSO2 ranged from 59 to 125% with an average of 100 ± 14.7%.

At an application rate of 0.5 lb ai/ A and a PHI of 59 61 days, total sethoxydim residue ( calculated as sum of DME plus DME OH) in canola forage ranged from < 1.0 3.5 ppm while the residues in Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 41 of 101 canola seed ranged from 3.7 35.0 ppm. These data are adequate to support the established sethoxydim tolerance level of 35.0 ppm for canola seed. However, the preferred commodity definition for this RAC is " Rapeseed, seed".

Carrot, roots MRID 42195001 ( D174374, M. I. Rodriguez, 8/ 7/ 92; D185410, M. I. Rodriguez, 8/ 25/ 93)

Field studies were conducted in CA, TX, MI, WA, NY, FL, WI and NJ. In all the studies, two applications were made at 0.5 lb ai/ A. The first application was made approximately 2 to 3 weeks after carrot leaf emergence and the second application was made within 21 to 28 days of harvest. All sprays included crop oil concentrate.

Carrot root samples were harvested and then frozen at less than  10 ° C until homogenized into ground carrot pulp. After processing, the samples were frozen again until analysis. Samples were stored for 12 months prior to analysis. No storage stability data were provided in this study; however, HED concluded that storage stability data developed for sugar beets adequately covered the storage interval used for carrot samples.

Method 30 G, with modifications ( use of C18 cleanup column if interfering peaks were present) was used for analysis of carrot samples. Recoveries for samples fortified with sethoxydim, MSO and 5 OH MSO2 at levels ranging from 0.05 ppm to 0.7 ppm were 95 116% for DME and 83 121% for DME OH. The results of the residue analysis indicated that the maximum residue recovered in treated carrots was 0.72 ppm ( PHI = 25 days).

In the 8/ 7/ 92 review, HED requested additional field trials on carrots. However, HED later determined that sethoxydim data for carrots show similarity to data obtained for other crops ( sugar beets, sweet potatoes, bulb vegetables, and root/ tuber crops) and thus, the data submitted are adequate ( D185410, M. I. Rodriguez, 8/ 25/ 93). Accordingly, the available data are adequate to support the established tolerance level of 1.0 ppm for " carrot, roots".

Cherry ( sweet and tart) MRID 41236401 ( PP9F3804/ PP9H5589, S. Inasi, 8/ 8/ 90)

A total of 12 field trials were conducted in 5 states for sour cherries and in 4 states for sweet cherries. Application rates ranged from 0.8 lb ai/ A ( 0.8X) to 1.5 lb ai/ A ( 1.5 X) and PHIs ranged from 7 to 43 days. Samples were stored frozen for 28 to 45 months. The storage stability data submitted as a response to the Craven DCI show that MSO and 5 OH MSO2 are stable in cherries for 5 and 3 years, respectively.

Method 30 G was used for analysis. Samples of stone fruits were fortified with 0.05, 0.5 and 1.0 ppm of sethoxydim, MSO and 5 OH MSO2; recovery for residues of sethoxydim and its metabolites in/ on sweet and sour cherries and peaches ranged from 74 108 percent at all three levels.

At a PHI range of 7 to 43 days the total residues of DME and 5 OH DME observed in 7 samples Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 42 of 101 of each fruit were < 0.13 ppm. The available data are adequate to support the current tolerance level of 0.2 ppm for cherry, sweet and cherry, sour.

Clover Hay and Forage MRID 42353601 ( D179955 & D179957, M. I. Rodriguez, 9/ 16/ 93)

Thirteen crop field trials were conducted in the states of OR, ID, MN, NB, TN, NY, MO, CA, and TX. Each trial consisted of two treated plots ( one designated to produce forage and another one to produce hay) and two untreated control plots ( one for forage and one for hay). Each of the treated plots was subdivided into three equal replicate plots. Poast ® Herbicide was applied at rates of 0.5, 0.5, and 0.3 lb ai/ A before the first, second, and third cuttings, respectively. For all trials, three cuttings during a single season were performed. Poast ® Herbicide was applied at preharvest intervals of 20 21 days for clover hay, and 6 7 days for clover forage. At each site, the plot designated to produce forage was treated 13 days after the plot designated to produce hay in order that both could be harvested on the same day for each cutting. The general sequence was herbicide application, cutting, application, cutting, and final application and cutting. The clover hay plots were cut as forage 20 21 days after each Poast ® application and allowed to dry in the field for 2 8 days to produce hay. Hay samples were then collected and frozen. Clover forage was harvested 6 7 days after each Poast ® application.

The clover forage and hay samples were stored at less than  5 oC until analyzed. A maximum of 24 months elapsed between harvest and analysis of samples. Storage stability data were not submitted with this study. HED concluded that data generated for corn forage adequately covers the use in/ on clover forage. The storage stability data for alfalfa hay does not cover the storage duration of the clover hay, therefore, these data can not be translated. However, as the stability of sethoxydim under similar conditions has been demonstrated with numerous other crops ( sugar beet, potato, head lettuce, beans, snap, peanut, hay, beans, succulent, peas, succulent, and soybeans, forage), HED concluded these data are acceptable for translation and that no storage stability data are required for clover hay.

Methods 30 G and 30H were used for analysis of forage and hay samples, respectively. Mean method recoveries were 97 ± 12% ( N= 52) for clover forage and 96 ± 17% ( N= 60) for clover hay. Control samples were fortified with MSO and 5 OH MSO2. Fortifications ranged from 0.5 ppm to 30 ppm ( per metabolite) for clover forage and 0.5 ppm to 50 ppm ( per metabolite) for clover hay.

The clover hay samples showed a maximum sethoxydim residue level of 50.7 ppm ( sample in OR, first cutting). Samples from other sites and cuttings had residue levels ranging from 3.3 ppm to 48 ppm. The mean total sethoxydim residue was 19.3 ppm. Replicate samples at the site with the highest residue contained 5.4/ 5.9 ppm ( duplicate analyses), 48.3/ 50.7 ppm ( duplicate analyses), and 49.8 ppm total residues.

The clover forage samples showed a maximum sethoxydim residue level of 30.9 ppm ( sample at another site in OR, third cutting). Samples from other sites and cuttings had residue levels ranging from 1.9 ppm to 30.6 ppm. The mean total sethoxydim residue was 14.8 ppm. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 43 of 101 The maximum residue detected in the clover hay samples was 50.7 ppm, which is slightly more than the tolerance level of 50 ppm. Thus, the established tolerance level for clover hay should be increased to 55 ppm, while the established tolerance level of 35 ppm is adequate for clover forage.

Coriander ( D238439, W. D. Cutchin and M. J. Nelson, 4/ 8/ 98)

Although no residue data were submitted for coriander, HED recommended a tolerance level of 4.0 ppm for this commodity for the following reasons: 1) there exists a tolerance of 4.0 ppm for the leafy vegetables ( except Brassica) crop group # 4, 2) parsley is a member of crop group # 4, and 3) a commodity definition has been established allowing translation of parsley, leaves data to cover cilantro ( coriander) [ Reviewer's Guide, B. A. Schneider, 6/ 14/ 02].

Corn In PP# 9F3806, the registrant submitted residue data ( MRID 41248401, 41248402, 41248403, and 41248404) to support a proposed label for Poast ® Herbicide involving directed spray application to the base of the corn plant to control annual grasses in field and sweet corn ( 30 day PHI) and proposed tolerances for field corn grain ( 0.1 ppm), sweet corn ( 0.2 ppm), corn forage ( 0.2 ppm) and corn fodder ( 0.2 ppm). These data were deemed adequate by HED ( PP# 9F3806, M. I. Rodriguez, 2/ 27/ 90). However, in PP4F04344 and PP# 2F04075, the registrant proposed to amend the registration to use Poast ® in an over the top application to sethoxydim resistant ( SR) field corn and sweet corn and to increase the application rate for the control of grassy weeds. Residue data submitted in support of PP4F04344 and PP# 2F04075 are summarized below.

Field Corn MRIDs 43178701 and 43455701 ( D210060, D210062, D208310, & D208312, M. I. Rodriguez, 7/ 24/ 95)

Two residue studies were submitted for review. In each study, trials were performed at the rate of 0.2 lb ai/ acre and at rate of 0.6 lb ai/ acre ( 2 applications of 0.3 lb ai/ acre each). In both cases, trials were performed across the United States and Canada. Poast ® was applied post emergent at the 3 to 5 leaf stage over the top of the corn using ground application equipment. For the proposed increased rate, a second Poast ® application was made 30 days later.

All samples were frozen at  5 oC immediately after harvest and maintained frozen until analysis. A maximum of 9 months lapsed between harvest and analysis of the samples. No concurrent storage stability data were included in the submission. However, HED had previously determined that two sethoxydim metabolites ( MSO and 5 OH MSO2) are stable under freezer storage conditions for 5 years in corn grain and corn forage ( D219970, L. Cheng, 4/ 9/ 96), and residues of parent, MSO2, M2SO2, and 5 OH MSO2 ( each separately spiked and analyzed) were stable in soybeans under frozen storage for 18 and 24 months ( D198048, L. Cheng, 4/ 26/ 94). Analytical Method A9003 was used for analysis. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 44 of 101 For the lower application rate, a total of 25 trials were performed. PHIs ranged from 59 90 days, from 75 106 days, and from 90 147 days for forage, silage, and fodder/ grain, respectively. Residues ranged from < 0.1  0.17 ppm, < 0.1  0.48 ppm, < 0.1  0.20 ppm, and were < 0.1 ppm for forage, silage, fodder, and grain, respectively.

For the higher application rate, a total of 24 trials was performed. PHIs ranged from 29 60 days, from 45 76 days, and from 60 117 days for forage, silage, and fodder/ grain, respectively. Residues ranged from < 0.10  1.52 ppm, < 0.10  1.62 ppm, < 0.10  2.11 ppm, and < 0.10  0.40 ppm for forage, silage, fodder, and grain, respectively.

The available data are adequate to support the current tolerance levels of 2.0, 3.5, and 0.5 ppm for field corn forage, fodder, and grain, respectively.

Sweet Corn MRID 45100501 ( D266208/ D266210, N. Dodd, 7/ 5/ 02)

A total of 14 trials were conducted in CA, FL, IA, IL, IN, MI, NC, NJ, OR, PA, WA, and WI during the 1997 growing season. In each test location, sethoxydim resistant hybrids of sweet corn received two applications with a 10 day retreatment interval of the proposed formulation, a 1.5 lb ai/ gal EC. Each application was made as an over the top postemergence treatment at a nominal rate of 0.3 lb ai/ A per application for a total of 0.6 lb ai/ A ( 1.0x the maximum proposed seasonal rate for sweet corn).

Sweet corn RAC samples were collected at normal crop maturity and then frozen prior to residue analysis. Fresh sweet corn ( kernels plus cob with husk removed) and forage were collected 30 days after the second treatment. Stover was collected according to normal practices, and led to harvest from 33 to 85 days after the second treatment. Samples were kept in a freezer for up to 7.5 to 10.5 months prior to analysis. No concurrent storage stability data were included in the submission. However, HED had previously determined that two sethoxydim metabolites ( MSO and 5 OH MSO2) are stable under freezer storage conditions for 5 years in corn grain and corn forage ( D219970, L. Cheng, 4/ 9/ 96), and residues of parent, MSO2, M2SO2, and 5 OH MSO2 ( each separately spiked and analyzed) were stable in soybeans under frozen storage for 18 and 24 months ( D198048, L. Cheng, 4/ 26/ 94).

Fresh corn, forage, and stover were analyzed by BASF Analytical Methods A9003, 30G, and 30H, respectively. Concurrent method recoveries indicated these methods were adequate for data collection. Average recoveries were 92, 99, and 101% for MSO in sweet corn, forage and stover, respectively. Average recoveries were 81, 91 and 88% for 5 OH MSO2 in sweet corn, forage and stover, respectively.

Following analysis of 1.0x treated samples that were collected at the proposed 30 day PHI, the combined residues of DME and DME OH ( calculated as total sethoxydim) were < 0.10< 0.34 ppm in/ on sweet corn grain and < 0.38< 2.67 ppm in/ on sweet corn forage. The combined residues in/ on treated samples of sweet corn stover, collected at 33 85 day PHI, were < 0.16 < 3.32 ppm. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 45 of 101 The residue decline data showed trends of lower residues with longer PHIs in/ on sweet corn grain and forage. There was no decline trend for stover as residues remained consistent through the 71 to 91 day sampling intervals. The available data are adequate to support the current tolerance levels of 0.4, 3.0, and 3.5 ppm for sweet corn grain, forage, and stover, respectively.

Cotton, undelinted seed MRID 43062205 ( D198048, L. Cheng, 4/ 26/ 94)

Field trials were conducted in CA, GA, MS, and TX. Three applications were made at 0.43 0.48 lb ai/ A/ application at 21 day intervals approximating the 3 x 0.47 lb ai/ A label rate. Harvests were made at 40 or 42 days after the last application. Cotton was mechanically ginned immediately. Cottonseeds with lint were frozen after harvest and shipped.

Samples were stored for up to 5 months before residue analyses. HED noted that storage stability data previously generated from soybean seeds indicated stability of sethoxydim metabolites during this period. The stability data were not generated by Craven labs.

Residue samples were analyzed by BASF Method 30A. Recoveries from fortified control sample were adequate. Average recoveries in cottonseeds were 76.0 ± 10.7% for MSO and 77.9 ± 2.5% for 5 OH MSO2.

Residues in cottonseeds resulting from treatment of cotton with sethoxydim ranged from 0.66 to 4.01 ppm. The available data are adequate to support the current tolerance level of 5.0 ppm for cotton, undelinted seed.

Cranberry MRID 41627001 ( PP0E3909, M. J. Nelson, 2/ 14/ 91)

Five trials were conducted in WI ( 2), MA ( 1), and WA ( 2). One to three applications at 0.5 to 2.0 lbs ai/ A were applied to cranberries. PHIs of 31 to 110 were utilized.

Samples were harvested at normal maturity and stored frozen 5 29 months prior to analysis by Method 30G. Control samples were fortified with sethoxydim, MSO and 5 OH MSO2 at levels ranging from 0.05 to 5 ppm. Average recoveries were 93, 88, and 96% for sethoxydim, MSO and 5 OH MSO2, respectively.

Storage stability data were not submitted for cranberries. The registrant referenced data from other crops ( strawberries, cherries, soybeans, peanut hay, and succulent peas) that indicated storage stability for sethoxydim and its metabolites for up to a 60 month period; however, these data, except for soybeans, were generated by Craven Laboratories ( D165411, L. Cheng, 9/ 23/ 91). Field trials conducted to replace the Craven generated data show that sethoxydim and it's metabolites are stable in 13 different matrices ( including strawberries and cherries) for 3 to 5 years. These data are translatable to cranberries.

Overall, total residue of sethoxydim ranged from 0.25 to 5.0 ppm. At an application rate of 1.0 lb Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 46 of 101 ai/ A ( 1x maximum rate) and a PHI of 60 days, residues were 1.2 ppm and 2.20 ppm ( 1 sample).

For the current use pattern, the maximum residue found ( 2.2 ppm) is greater than the tolerance of 2 ppm. Therefore, the sethoxydim tolerance level for cranberries should be increased to 2.5 ppm.

Flax, seed and straw MRID 43801409 ( D237724, L. Cheng, 7/ 28/ 97)

Studies were conducted to replace flax residue data generated by Craven Laboratories. Three field trials on flax were conducted in MN, ND, and SD. Flaxseed and straw were harvested 75 days after three applications of the 1.5 lb/ gal EC, each at 0.19 lb ai/ A ( 1x the maximum registered rate). Broadcast applications were made in 5 gal/ A using ground equipment.

Samples were bagged and frozen ( temperature unspecified) within 2.5 hours of collection and were stored frozen for a maximum of 10 months. HED noted that storage stability data on 13 matrices submitted with the residue data on tomatoes, broccoli, mustard greens, and cabbage ( D219970, 4/ 9/ 96, L. Cheng) indicate that sethoxydim and metabolites are stable for 3 5 years. Thus, adequate supporting storage stability data were available to cover the storage intervals reflected in the field trials.

Samples were analyzed using GC/ FPD Methods 30 ( seed) and 30H ( straw). Concurrent recoveries were adequate; for flax seed recoveries were 69.5% and 71.5% for MSO and 94.6% and 76.8% for 5 OH MSO2; for flax straw recoveries were 100% and 69.5% for MSO and 107% and 83.2% for 5 OH MSO2.

At a total application rate of 0.57 lb ai/ A and a PHI of 75 days, combined residues of sethoxydim were 0.49 0.86 ppm in flax seed and 0.25 0.43 ppm in flax straw. Because flax straw is not considered a significant livestock feed item ( see Table 1, Series 860 OPPTS Test Guidelines) the tolerance for flax straw should be revoked. For flax, the maximum rate per application is 0.28 lb ai/ A, with a total maximum per season of 0.75 lb ai/ A. Accordingly, the field trial data reflects a use rate of approximately 0.76x. To account for the higher rate on the label, the established tolerance level of 5.0 ppm for flax, seed is appropriate.

Fruit, Citrus, Group 10 MRIDs 40492601, 40492602 and 40492603 ( Summary in 92166069)

Field trials were conducted on oranges, lemons, and grapefruit to establish a tolerance for the citrus fruits crop group. Trials were conducted in FL, CA, and TX for oranges and grapefruit; and in AZ and CA for lemons. The number and distribution of field trials is adequate to satisfy reregistration data requirements. The maximum frozen storage interval (<  5  C) was 50 months. This interval was supported by storage stability data on oranges, strawberries, and succulent peas, which showed no significant loss of residues in samples held at <  5  C for up to 31, 60, and 52 months, respectively. Fortification/ recovery experiments were run at levels ranging from 0.05 to 5.0 ppm, and showed recoveries ranging from 68 112% for all three representative crops. Control samples were fortified with sethoxydim and/ or metabolites MSO and 5 OH MSO2 and Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 47 of 101 analyzed concurrently with treated samples, using Method 30G. The available data are adequate to support the current tolerance level of 0.5 ppm for crop group 10.

Oranges Sethoxydim was applied 4 5 times at a rate of 0.5 lbs/ A/ application, with a minimum retreatment interval ( RTI) of 20 days, and a PHI of 3 15 days. Exaggerated rate studies consisted of 5 6 applications at 1.0 or 2.0 lbs/ A/ application. The maximum combined residue level at a 1x treatment rate was 0.30 ppm; the maximum combined residue level at a 2x treatment rate was 0.35 ppm.

Lemons Sethoxydim was applied 4 6 times at a rate of 0.5 lbs/ A/ application, with a minimum retreatment interval ( RTI) of 20 days, and a PHI of 3 15 days. Exaggerated rate studies consisted of 3 6 applications at 1.0 lb/ A/ application. The maximum combined residue level at a1x treatment rate was < 0.10 ppm; the maximum combined residue level at a 2x treatment rate was 0.37 ppm.

Grapefruit Sethoxydim was applied 4 5 times at a rate of 0.5 lbs/ A/ application, with a minimum retreatment interval ( RTI) of 20 days, and a PHI of 3 15 days. Exaggerated rate studies consisted of 4 5 applications at 1.0 lbs/ A/ application. The maximum combined residue level at a1x treatment rate was 0.27 ppm; the maximum combined residue level at a 2x treatment rate was 0.46 ppm.

Fruit, Pome, Group 11 MRIDs 40576101 and 40576102 ( Summary in 92166070)

Field trials were conducted on apples ( 13) and pears ( 6) to establish a tolerance for the pome fruits crop group. Trials were conducted in CA, CT, NY, MI, PA, OR, and WA for apples; and in CA, MI, PA, OR, and WA for pears. The number and distribution of field trials is adequate to satisfy reregistration data requirements. The maximum frozen storage interval (<  5  C) was 38 months. This interval was supported by storage stability data on apples and strawberries, which showed no significant loss of residues in samples held at <  5  C for up to 37 and 60 months, respectively. Fortification/ recovery experiments were run at levels ranging from 0.05 to 1.0 ppm, and showed recoveries ranging from 64 108% for the two representative crops. Control samples were fortified with sethoxydim and/ or metabolites MSO and 5 OH MSO2 and analyzed concurrently with treated samples, using Method 30G. The available data are adequate to support the current tolerance level of 0.2 ppm for crop group 11.

Apples Sethoxydim was applied 3 5 times at a rate of 0.5 lbs/ A/ application ( 1x), with a minimum retreatment interval ( RTI) of 11 days, and a PHI of 7 15 days. Exaggerated rate studies consisted of 4 applications at 2.0 lbs/ A/ application ( 4x). The maximum combined residue levels at treatment rates of 1x and 4x was 0.15 ppm. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 48 of 101 Pears Sethoxydim was applied 3 5 times at a rate of 0.5 lbs/ A/ application, with a minimum retreatment interval ( RTI) of 25 days, and a PHI of 10 17 days. The maximum combined residue level at a 1x treatment rate was < 0.10 ppm.

Grapes MRID 43801410 ( D237724, L. Cheng, 7/ 28/ 97)

Studies were conducted to replace existing grape residue data generated by Craven Laboratories. Six field trials on grapes were conducted in CA( 2), MI, NY, NC, and WA. Grapes were harvested 50 days after two applications of the 1.5 lb/ gal EC, each at 0.47 lb ai/ A ( 1x the maximum registered rate). Broadcast applications were made in 5 gal/ A using ground equipment.

Samples were bagged and frozen ( temperature unspecified) within 2.5 hours of collection and were stored frozen for a maximum of 9 months prior to analysis. HED noted that storage stability data on 13 matrices submitted with the residue data on tomatoes, broccoli, mustard greens, and cabbage ( D219970, 4/ 9/ 96, L. Cheng) indicate that sethoxydim and metabolites are stable for 3 5 years. Thus, adequate supporting storage stability data were available to cover the storage intervals reflected in the field trials.

Method A9003 was used for sample analysis. Concurrent recoveries were adequate; recoveries ranged from 70% to 92% for MSO and from 77% to 89% for 5 OH MSO2. Residues in grapes resulting from treatment with sethoxydim ranged from < 0.1 to 0.56 ppm. The available data are adequate to support the current tolerance level of 1.0 ppm for grape.

Horseradish No MRID number ( D251542, G. J. Herndon, 12/ 10/ 98)

In PP# 9E5049, the registrant submitted a request for establishment of a tolerance for residues of sethoxydim and its metabolites in/ on horseradish at 4.0 ppm based on existing data from sugar beets, carrots, potatoes and sweet potatoes. HED concluded that since the cultural practices for horseradish are in line with those of carrots, potatoes, sugar beets, and sweet potatoes, the residue data requirements for horseradish were satisfied based on residue data for these crops ( D251542, G. J. Herndon, 12/ 10/ 98).

Juneberry, Lingonberry and Salal ( D278583, N. Dodd, 7/ 19/ 02)

No residue data were submitted for these crops. The registrant proposed to use residue data on blueberry and caneberry to support use on lingonberry, juneberry, and salal. HED concluded that residue data for sethoxydim on blueberries could be used for lingonberries, juneberries, and salal given that similar use patterns. Based on the blueberry residue data, HED noted that residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety are not expected to exceed the proposed tolerance of 5.0 ppm in lingonberry, juneberry, and salal. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 49 of 101 Lentil, seed No MRID number ( D165411, L. Cheng, 9/ 23/ 91; D237724, L. Cheng, 7/ 28/ 97)

In D165411 ( L. Cheng, 9/ 23/ 91), HED noted that samples from lentil field trials evaluated in the Phase IV review had been analyzed by Craven Laboratories. HED also indicated that the use pattern of sethoxydim on dry peas ( 40 ppm, 30 day PHI) is similar to lentils ( 30 ppm, 50 day PHI), and therefore, residue data generated on dry peas are translatable to lentils. Residue data for dry peas ( MRID 43801414) were submitted in 1995 and found acceptable ( D237724, L. Cheng, 7/ 28/ 97). The 20 day longer PHI for lentils supports a lower tolerance level for lentils than for dry pea. Thus, the available data are adequate to support the established 30 ppm tolerance level for lentil, seed.

Nectarine MRID 41236404 ( PP9F3804/ PP9H5589, S. Inasi, 8/ 8/ 90)

For nectarines, one field trial was conducted in CA. Nectarines were harvested 17 days after the last of two applications of sethoxydim at 0.5 lb ai/ A. Only one nectarine sample was analyzed; the total residue was < 0.1 ppm. HED determined that the residue data from the analysis of peaches ( 13 samples) can be translated to nectarines.

Peach MRID 41236402 ( PP9F3804/ PP9H5589, S. Inasi, 8/ 8/ 90)

For peaches, 6 field trials were conducted in 6 states at 1 2X dose rates with a PHI of 10 89 days. Samples were store for up to 45 months. The registrant submitted freezer storage stability data for cherries fortified with 1.0 ppm each of MSO and 5 OH MSO2 that indicated that these metabolites are stable for at least 26 33 months.

Method 30 G was used for analysis. Samples of stone fruits were fortified with 0.05, 0.5 and 1.0 ppm of sethoxydim, MSO and 5 OH MSO2; recovery for residues of sethoxydim and its metabolites in/ on sweet and sour cherries and peaches ranged from 74 108 percent at all three levels. Recovery of these metabolites from plums at all three levels ranged from 84 92%. HED noted that these data were adequate to establish that recoveries of the herbicide and its metabolites in/ on sweet and sour cherries, peaches and plums were within acceptable range.

For peaches, the total sethoxydim residues detected in all thirteen treated samples analyzed were less than 0.1 ppm.

Peanut MRID 43801408 ( D237724, L. Cheng, 7/ 28/ 97)

The Phase IV review indicates that peanut crop field trials ( MRID 92166063) were conducted in all the major peanut growing areas using ground equipment only ( aerial mode of application permitted). Sethoxydim was applied at 1 x 0.3 + 1 x 0.2 lb ai/ A ( label maximum of 0.47 lb Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 50 of 101 ai/ A/ season). Samples of nuts and hulls were collected at 20 47 days ( label PHI= 40 days) and contained less than 25 ppm ( nut meat) and 5 ppm ( hulls) residues. Subsequently, it was determined that some of the data was analyzed by Craven Laboratories. To replace the existing peanut data generated by Craven Laboratories, three field trials on peanuts were conducted in GA, NC, and TX ( MRID 4381408). Peanuts were harvested 40 days after two applications of the 1.5 lb/ gal EC formulation, the first at 0.09 lb ai/ A and the second at 0.38 lb ai/ A ( 1x the maximum registered seasonal rate). Broadcast applications were made in 5 gal/ A using ground equipment.

Samples were bagged and frozen ( temperature unspecified) within 2.5 hours of collection and were stored frozen for a maximum of 10 months. Storage stability data for soybeans indicate that sethoxydim and its metabolites are stable for up to 24 months and are translatable to peanuts.

Sample analysis was performed using GC/ FPD Method 30. Concurrent recoveries were adequate; for peanut nutmeat recoveries were 120% and 86% for MSO and 139% and 93% for 5 OHMSO2 for peanut hulls recoveries were 96% and 72% for MSO and 97% and 89% for 5 OHMSO2 . Residues in peanut nutmeat were 5.3 12.5 ppm and these data are adequate to support the 25 ppm tolerance for peanuts.

Pea, succulent MRID 43801415( D237724, L. Cheng, 7/ 28/ 97)

Studies were conducted to replace existing succulent pea residue data generated by Craven Laboratories. Field trials on peas were conducted in CA( 2), DE, ID, MN, OR, and WI. Pea pods were harvested 15 days after the second of two applications of the 1.5 lb/ gal EC formulation, the first at 0.28 lb ai/ A and the second 14 days later at 0.47 lb ai/ A ( 1x the maximum registered seasonal rate). Broadcast applications were made in 5 gal/ A using ground equipment.

Samples of bean pods were bagged and frozen within 4.5 hours of collection. Samples were stored frozen for a maximum of 15 months prior to analysis. HED noted that storage stability data on 13 matrices submitted with the residue data on tomatoes, broccoli, mustard greens, and cabbage ( D219970, 4/ 9/ 96, L. Cheng) indicate that sethoxydim and metabolites are stable for 3 5 years. Thus, adequate supporting storage stability data were available to cover the storage intervals reflected in the field trials.

Method 30G was used for sample analysis. Concurrent recoveries were adequate; recoveries ranged from 65% to 101% for MSO and from 86% to 121% for 5 OH MSO2. Residues in succulent peas were 1.4 7.0 ppm. The available data are adequate to support the established 10 ppm tolerance for residues of sethoxydim in/ on succulent peas.

Pea, dry, seed MRID 43801414 ( D237724, L. Cheng, 7/ 28/ 97) All samples from the original U. S. residue trials were analyzed by Craven. Non Craven pea residue trials were conducted in Manitoba, Saskatchewan, Canada and used less than the maximum use pattern. To replace the existing dry pea residue data generated by Craven Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 51 of 101 Laboratories, field trials on dry peas were conducted in ID and WA. Peas were harvested 30 days after the second of two applications of the 1.5 lb/ gal EC formulation, the first at 0.28 lb ai/ A and the second 14 days later at 0.47 lb ai/ A ( 1x the maximum registered seasonal rate). Broadcast applications were made in 5 gal/ A using ground equipment.

Samples of peas were bagged and frozen ( temperature unspecified) within 1.75 hours of collection. Samples were stored frozen for a maximum of 13 months prior to analysis. HED noted that storage stability data on 13 matrices submitted with the residue data on tomatoes, broccoli, mustard greens, and cabbage ( D219970, 4/ 9/ 96, L. Cheng) indicate that sethoxydim and metabolites are stable for 3 5 years. Thus, adequate supporting storage stability data were available to cover the storage intervals reflected in the field trials.

Method 30 was used for analysis. Concurrent recoveries were adequate; recoveries ranged from 68 95% for MSO and from 80 122% for 5 OH MSO2. Residues in dry peas were 13.8 and 14.3 ppm. The available data are adequate to support the established 40 ppm tolerance for residues of sethoxydim in/ on dry pea, seed.

Pea forage and hay MRIDs 43801414 and 43801415 ( D237724, L. Cheng, 7/ 28/ 97)

In conjunction with each of the field trials on succulent and dry peas, the registrant provided data on pea vines ( forage) and hay. Vine and hay samples were harvested 15 30 days following two applications of the 1.5 lb/ gal EC formulation at 0.28 and 0.47 lb ai/ A. The application rates and PHIs all reflected the current label rates for these crops.

Sethoxydim residues in legume forage samples were analyzed using BASF Methods 30G and 30H following up to 15 months in frozen storage. Concurrent recoveries were adequate; for pea forage recoveries were 63 100% for MSO and 67 84% for 5 OH MSO2; for pea hay recoveries were 70 122% for MSO and 83 108% for 5 OH MSO2 .

Total residues of sethoxydim were reported for dry pea forage ( 3.0 & 5.4 ppm) and hay samples ( 11.4 & 12.8 ppm). In the succulent pea forage and hay samples, total residues of sethoxydim ranged from 1.8  9.4 ppm and 4.1  24.9 ppm, respectively. The data are adequate to support tolerances of 20 and 40 ppm for pea forage and hay, respectively.

Peppermint, tops/ Spearmint, tops MRID 42101701 ( D172349, W. D. Wassell, 2/ 11/ 92)

Nine crop field trials were conducted during 1988 in six states ( IN ( 2), MI, OR ( 2), UT, WA ( 2) and WI) to provide residue chemistry data to support the registration of sethoxydim for use on mint. Four field trials used spearmint and five used peppermint. In all trials, two applications of Poast ® Herbicide were made using ground equipment at rates of 0.5 lbs ai/ A. For all applications, a crop oil concentrate was used at a rate of 1 quart/ A. Retreatment intervals of 14 to 18 days were observed and all second applications were made 20 days prior to cutting of the mint. Whole green plant samples were collected on the day of cutting. Plants were allowed to air dry for Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 52 of 101 one to four days and then collected as mint hay samples. In one field trial, Washington, mint hay samples were not collected since mint in this area is normally processed the same day as cutting.

Mint green plant, mint hay and mint process samples were stored from harvest to analysis for a maximum of 21, 20 and 17 months, respectively. Previously submitted storage stability data for alfalfa hay, corn forage and dry beans were cited by the registrant; however, HED concluded that the cited data were not adequate to demonstrate the stability of sethoxydim per se in or on mint commodities over the period between harvest and analysis and requested the submission of storage stability data for mint or a similar crop that reflects the interval and conditions of storage for the samples of the submitted studies. Subsequently, storage stability data for 13 crop matrices were submitted which demonstrate the stability of sethoxydim and it's metabolites for up to 3 to 5 years. These data may be translatable to mint.

Mint green plant and mint hay samples were analyzed according to modified versions of BASF Methods 30G and 30H, respectively, or according to BASF Method 278 for either matrix. Concurrent recoveries were adequate; for mint green plant samples, recoveries were 74 122% ( 97 ± 17%) for MSO and 78 110% ( 95 ± 12%) for 5 OH MSO2; for mint hay samples, recoveries were 61 105% ( 82 ± 16%) for MSO and 60 111% ( 89 ± 15%) for 5 OH MSO2.

Total residues were 2.5 25.9 ppm and 2.5 9.9 ppm in mint green plant and mint hay samples, respectively. The available data are adequate to support the current tolerance level of 30 ppm for " peppermint, tops" and " spearmint, tops".

Pistachio No MRID number ( D256970, N. Dodd, 8/ 9/ 01)

No residue data have been submitted for pistachios. HED noted that the proposed use of Poast ® Herbicide on pistachios is the same as the registered use on the tree nuts crop group ( almonds, pecans, walnuts) with respect to lb ai/ A/ application, lb ai/ A/ season, and PHI. Residue data for sethoxydim and its metabolites on almonds ( nuts and hulls) ( MRID 41428501), pecans ( MRID 41428502), and walnuts ( MRID 41428503) were previously reviewed in connection with establishment of the sethoxydim tolerance on the tree nuts crop group at 0.2 ppm ( PP# 0F3855, M. J. Nelson, 2/ 7/ 91). HED determined that data on walnuts, pecans, and almonds can be used in lieu of residue data on pistachios to support the proposed tolerance on pistachios. Thus, the existing tree nut tolerance level of 0.2 ppm is adequate to cover the pistachio use.

Rhubarb MRID 41072001 One rhubarb field trial was conducted in MI in 1986. Due to the low acreage of rhubarb and the regional registration of rhubarb, the one field trial is adequate to satisfy reregistration data requirements. Sethoxydim was applied at a rate of 0.3 lbs/ ai/ A as the formulation Poast 1.5 EC. The maximum combined residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety in rhubarb were 0.24 and 0.16 ppm for samples harvested following 15 and 30 day Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 53 of 101 PHIs, respectively. These residue levels indicate that the existing tolerance level of 0.3 ppm is adequate for rhubarb.

Safflower MRID 44864501 ( D257559, N. Dodd, 1/ 24/ 02)

Four field trial studies using safflower were conducted in 1988. The studies were conducted in Region 10 ( 1 study), Region 5 ( 2 studies), and Region 7 ( 1 study). In the trials, sethoxydim ( Poast ® 1E) was applied twice to each test plot at a rate of 0.5 lb ai/ A/ application ( total of 1.0 lb ai/ A/ season). At a PHI of 30 days, maximum residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety in safflower seed were 12 ppm.

Based on the storage stability of sethoxydim, MSO2, M2SO2, and 5 OH MSO2 in soybean seeds for 24 months, HED concludes that residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety are stable in safflower seed and meal for 24 months, which is longer than the time of safflower seed and meal sample storage.

The available field trial data indicate that residues of sethoxydim and its metabolites containing the 2 cyclohexen 1 one moiety will not exceed 15 ppm in/ on safflower as a result of the proposed use; however, an adequate number of field trials have not been submitted. Under OPPTS 860.1500, five field trials are required for safflower, with suggested distribution in Region 7 ( 2 trials) and Region 10 ( 3 trials). Therefore, two additional studies from Region 10 should be submitted. Pending submission and review of the Region 10 trials, the established tolerance level of 15 ppm is adequate for sunflower, seed.

Soybean Seed MRIDs 100535 and 43801412 ( D237724, L. Cheng, 7/ 28/ 97; D182749, B. Schneider, 11/ 23/ 92)

In 1991, HED determined that some residue data for soybean seed and hay evaluated in the Phase IV review had been generated by Craven Laboratories. In 1992, the registrant submitted a revised label proposing a 75 day PHI and resubmitted the non Craven data to support the revised label. The non Craven data were generated from ten soybean seed field trials ( MRID 100535) conducted in five states ( IL, MI, MO, NC, and NJ). Only data from the tests conducted at PHIs ranging from 17 78 days were resubmitted. All of the field trials were applied as ground application directly to the emerged weeds using two applications of sethoxydim ( Poast ® Herbicide) at 0.5 lb a. i./ A ( 1X) with PHIs ranging from 17 78 days. All samples analyzed for seed after harvest were stored frozen at <  5 ° C until analysis. The total sethoxydim residue ( calculated as sum of DME plus DME OH) in soybean seed ranged from 2.52  8.7 ppm. At 78 and 75 day PHIs, the sethoxydim residues were 3.5 and 6.5 ppm, respectively.

In MRID 43801412, the registrant submitted the results of studies conducted to supplement existing soybean residue data in order to satisfy geographic representation and PHI amendment. Sethoxydim Summary of Analytical Chemistry and Residue Data Barcode: D318169 54 of 101 Field trials on soybeans were conducted in LA, TN, AR, IA, and MN. Soybeans were harvested 75 days after the second of two applications of the 1.5 lb/ gal EC formulation, each at 0.47 lb ai/ A ( 1x the maximum registered rate). Broadcast applications were made in 5 gal/ A using ground equipment. Samples of soybeans were bagged and frozen ( temperature unspecified) within 2 hours of collection. Samples were stored frozen for a maximum of 9 months prior to analysis using GC/ FPD Method 30. Total residues in soybean seed ranged from 0.4  15.2 ppm. These data are adequate to support the existing tolerance level of 16 ppm for soybean, seed.

Hay MRIDs 153602 and 43801412 ( D237724, L. Cheng, 7/ 28/ 97)

As indicated above, in 1992, the registrant submitted a revised label proposing a 75 day PHI for soybeans. To support the revised label, non Craven data for soybean hay were submitted. These data were generated from 14 soybean hay field trials ( MRID 153602) conducted in 5 states ( IL, MI, MN, MO, and NJ). These field trials include tests conducted at PHI ranging from 32 to 78 days. Samples used for hay were cut from the dried soybean stubble in the field. The total sethoxydim residue in soybean hay ranged from 2.01 ppm to 6.49 ppm. At 78 and 75 day PHIs, the sethoxydim residues in hay averaged 2.40 ppm and 2.49 ppm, respectively.