Page 1 of 20 **UNITED STA**

**TES ENVIRONMENTA L PROTECTION A** **GENCY** WA SHINGTON, D.C. 20460 **OFFICE OF CHEMICAL SAFETY AND**

**POLLUTION PREVENTION MEMORANDUM**  Date: 14 - August - 2013 Subject: **Linuron** . Petition for the Establishment of Permanent Tolerances and Registration

for Use on Coriander, Dill, Parsley, Pea (Dry), and Horseradish ; and Submission of Residue Anal ytical Methods of Plants and Animal Matrices . Summary of Analy tical C hemistry

and Residue Data. PC Code: 035506 DP Barcode s : D 404359, D 411652 Decision No.: 469722 Registration No. : 61842 - 23 Petition No.: 2E8083 Regulatory Action: Section 3 Risk Assessment T ype: NA Case No.: NA T XR No.: NA CAS No.: 330 - 55 - 2 MRID No.: See Appendix A 40 CFR : §180.184 From: Nancy

Tsaur, Chemist Risk Assessment Branch 3 (RAB3) Health Effects Division (7509P) Through: Steve Funk, Senior Chemist

Risk Assessment Branch 3 (RAB3) H ealth Effects Division ( 7509P ) To: Kristin Rury , Biologist, Risk Assessor

Risk Assessment Branch 3 (RAB3) Health Effects Division (7509P)Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 2 of 20 **Table of Contents** 1.0 Executive Summary ................................ ................................ ................................ ............ 3 2.0 Regulatory

Recommendations ................................ ................................ ............................ 3 2.1 Tolerance Considerations ................................ ................................ ................................ . 3 2.1.1 Enforcement Anal ytical Method ................................ ................................ ............... 3 2.1.2 Recommended Tolerances ................................ ................................ ........................ 4 2.2.3 Revisions to Petitioned - For Tolerances ................................ ................................ .... 5 2.2.4 International Harmonization ................................ ................................ ..................... 5 3.0 Introduction ................................ ................................ ................................ ......................... 5 3.1 Chemical Identity ................................ ................................ ................................ ............. 6 3.2 Phy sical/Chemical Characteristics ................................ ................................ ................... 6 3.3 Pesticide Use Pattern/Directions for Use (860.1200) ................................ ....................... 7 4.0 Metabolite/Degradate Residue Profile ................................ ................................ ................ 8 4.1 Nature of the Residue ................................ ................................ ................................ ....... 8 4.2 Comparison of Metabolic Pathway s ................................ ................................ ................ 9 4.3 Residues of Concern Summary and Rationale ................................ ................................ . 9 5.0 Residue Profile ................................ ................................ ................................ .................. 10 5.1 Residue Anal ytical Methods (860.1340) ................................ ................................ ........ 10 5.2 Submittal of Analy tical Reference Standards (860.1650) ................................ .............. 11 5.3 Storage Stability

(860.1380) ................................ ................................ .......................... 11 5.4 Residue Data ................................ ................................ ................................ .................. 12 5.4.1 Crop Field Trials (860.1500) ................................ ................................ .................. 12 5.4.2 Meat, Milk, Poultry and Eggs (860.1480) ................................ .............................. 13 5.5 Food Residue Profile ................................ ................................ ................................ ...... 13 6.0 Tolerance Derivation ................................ ................................ ................................ ........ 13 Appendix A. Summary

of Submitted Residue Chemistry Studies ................................ .............. 15 Appendix B. International Residue Limits Table for Linuron ................................ ..................... 16 Appendix C. OECD MRL Calculation Procedure Inputs/Outputs ................................ .............. 17Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 3 of 20 **1.0 Executive Summary**  Interregional Research Project No. 4 (IR- 4) has submitted a petition (PP#2E8083) for tolerances on coriander, dill, parsley , pea (dry), and horseradish ; and has proposed to add these uses to the Tessenderlo Kerley

label for Lorox® DF (EPA Reg. No. 61842 - 23). IR- 4 has submitted crop field trials utilizing comparable formulations, all of which consist of 50% active ingredient (ai) in a dry flowable formulation. The residue chemistry database is adequate for tolerance assessment of the proposed uses. Based on residues found in forage/foliage from three plant metabolism studies where the active ingredient was applied in a soil - directed fashion early in the growing season , linuron is understood to have s ys temic activity in plant s. The field trials indicate that finite residues are found in food commodities and that the residues concentrate upon drying herbs and/or processing dill for oil. Ithas been shown that linuron and its metabolites, including unknown metabolites characterized as polar, can be converted quantitative ly to 3, - 4 - dichloroaniline (3,4 - DCA). Therefore, l inuron can be regulated b y using the enforcement anal ytical method in which identified metabolites , unidentified polar components , and bound residues in plant and animal commodities are hydrol yzed to 3,4 - DCA. The total residue convertible to 3,4 - DCA will be compared to the reference dose for parent linuron for purposes of dietary risk assessment. Concomitant with this IR - 4 petition, additional analy tical method data have been submitted b y Tessenderlo Kerley

to support the newl y proposed uses. A new enforcement method for plant and livestock commodities was previously required as conditional data ( K. Rury , DP 375451 , 04/01/2010 ) . A high performance liquid chromatography /tandem mass spectrometry ( HPL C/MS/MS ) method based on extraction of residues and identification of parent and specific metabolites has been submitted. Also submitted was a method that hydrolyz es commodities with base to transform the total linuron residue to 3,4 - DCA. Gas chromatography with mass spectrometry detection ( GC/MS) i s used to quantitate the 3,4 - DCA. Independent laboratory validation of the latter method has been provided. Inreviewing these data, HED has determined that the continued use of a common moiety definition (1,3 - dichloraniline) is appropriate , and that the validated GC/MS method for 3,4 - DCA will be adequate for tolerance enforcement purposes. Thus, the requirement for additional enforcement analy tical methods is fulfille d. **2.0 R** **egulatory R ecommendations**  HED has examined the residue chemistry database for linuron and concluded that , provided a revised label and a revised Section F, there are no residue chemistry deficiencies that would preclude granting Section 3 registration for the requested crop commodity uses of linuron , or establishment of tolerances for residues of linuron . The specific tolerance recommendations are discussed in Section 2 .1 .2. **2. 1**  **Tolerance Considerations 2.1**  **.1 Enforcement**  **Analytical Method** Various acceptable enforcement method s are available.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 4 of 20 For linuron residues of concern in plant commodities, Method ABC - 68406 - M , is available and suitable for the enforcement of tolerances . This method involves reflux of crop samples in strong base to hydrol yz e residues of linuron and its metabolites to 3,4 - DCA. Then, 3,4 - DCA is anal yz ed b y gas chromatography with mass spectrometry detection ( G C/MS) . Based on the lowest level of method validation (LLMV) from the independent laboratory validation (ILV) study , the validated limit of quantitation (LOQ) is 0.01 ppm for linuron and its metabolites hydrol yz able to 3,4 - DCA in/on oily (so yb ean seed), watery

(celery), and starch (potato) crop matrices. In addition , Method ABC - 65790 is a confirmatory method that is also available that may be used to confirm results from the use of Method ABC - 68406 - M . In this method, extractions are conducted with methanol and each anal yt e is anal yz ed b y liquid chromatography /tandem mass spectrometry

(LC/MS/MS) . This method separately determines residues of linuron and metabolites 3 - (3,4 - dichlorophenyl) - 1 - methylurea (DCPMU), N - (3,4 - dichlorophenyl)urea (DCPU), and desmethyllinuron in crop commodities. Based on the LLMV , the validated LOQ is 0.01 ppm each for linuron, DCPMU, DCPU, and desmethyl linuron. For linuron residues of concern in livestock commodities Method ABC - 67638 - M is available and suitable for the enforcement of tolerances. Th is method involves reflux of livestock commodity samples in strong base to hydrol yz e residues of linuron and its metabolites to 3,4 - dichloroaniline (3,4 - DCA). Then, 3,4 - DCA is analyzed by gas chromatography with mass spectrometry detection ( G C/MS) . Based on th e LLMV, the validated LOQ is 0.01 ppm for linuron and its metabolites hydrolyzable to 3,4 - DCA in milk, muscle, and liver. **2. 1**  **.2 Recommended Tolerances**  In addition to the recommended tolerances listed below in Table 2.2.2, the tolerance with regional registration under 40 CFR § 180.184(c) for parsley, leaves (0.25 ppm) should be deleted. **Table 2.2.2**  **. Tolerance Summary for Linuron**  **.** Commodity Established/Proposed

Tolerance (ppm) HED - Recommended Tolerance (ppm) Comments

( correct commodity definition ) Cilantro, fresh leaves 3.0 1.5 coriander, leaves Cilantro, dried leaves 27 10 coriander, dried leaves Coriander, seed 0.01 0.05 Dillweed, fresh leaves 1.5 0.6 Dillweed, dried leaves 7.1 3.0 Dill, seed 0.3 0.5 Dill, oil 4.8 2.0 Horseradish 0.05 0. 05 Parsley, leaves 3.0 4.0 Parsley, dried leaves 8.3 3.0 Pea, dry, seed 0.08 0.06Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 5 of 20 **2.2.3 Revisions to Petitioned**  **- For Tolerances**  All of the petitioned - for tolerance level s (except for horseradish) must be revised to reflect the tolerance level s recommended by HED for linuron (3 - (3,4 - dichlorophenyl) - 1 - methoxy- 1 - methylurea) and its metabolites convertible to 3,4 - dichloroaniline, calculated as linuron, in or on the commodities . The Organization for Economic Cooperation and Development (OECD) calculation procedures were used to calculate the tolerance levels for the following three commodities: cilantro, fresh leaves; dillweed, fresh leaves; and pea, dry , seed. Based on the OECD calculations, all three tolerance levels should be decreased. Instead of using the OECD calculator due to a limited number of field trials, the formula of 5X the mean was used to establish tolerance levels for the following three commodities: coriander, seed; dill, seed; and parsley , leaves. Based on this calculation method, all three tolerance levels should be increased. For the dried herbs (cilantro, dillweed, and parsley) and the dill oil, the formula of the highest average field trial (HAFT) multipl ied by the concentration factor was used to calculate the recommended tolerance levels (the concentration factors were derived from dividing the average dried/oil commodity

residue by

the average fresh commodity residue). Based on this calculation method, all four tolerance levels should be decreased. **2.2.4 International Harmonization**  There are no established maximum residue limits (MRL s) for linuron in Codex for any agricultural commodity . Furthermore , no Canadian or Mexican MRL s have been establis hed for linuron. Therefore, there are no harmonization issues that exist with respect to U.S. tolerances. **2.3 Label Recommendations**  Since there are livestock feed items associated with field pea, the following restriction should be added to the label: “Do n ot apply to field pea used for livestock feed.” **3.0 Introduction**  Linuron is a selective phenylurea herbicide used to control broadleaf weeds and annual grasses by s ys temicall y inhibiting photos ynthesis. It may be applied pre - plant, pre - emergence, post emergence or post - transplant to various field crops and noncrop areas.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 6 of 20 **3.1 Chemical Identity**  **Table 3.1.**  **Linuron Nomenclature.** 

Com pound

Common name Linuron Com pany experimental name DPX - Z0326 IUPAC name 3 - (3,4 - dichlorophenyl) - 1 - me thoxy - 1 - methylurea CAS name N ‘- (3,4 - dichlorophenyl) -N - methoxy -N

- methylurea CAS # 330 - 55 - 2 End - use product/EP Metabolite

Common name DCPMU Chemical name 3 - (3,4 - dichlorophenyl) - 1 - me thylurea Metabolite

Common name DCPU Chemical name N - (3,4 - dichlorophenyl)urea Metabolite

Common name Desmethyl linuron Chemical name N - (3,4 - dichlorophenyl) -N ‘- methoxyurea **3.2 Physical/Chemical Characteristics**  Linuron is an off

- white powder with a molecular weight of 249.1 g/mol , which indicates that the potential to cross biological barriers, such as the skin, is somewhat limited. Furthermore, the low log of the octanol/water partition coefficient (log P ow = 2.76 at 25  C ) suggests low potential for dermal absorption; the relativ ely low water solubility and low lipophilic potential, indicate that linuron is not likely

to bioaccumulate. The vapor pressure for linuron is low (3 .011 × 10 - 7 mm Hg at 25  C ), and linuron is considered relatively insoluble in water . The Henry’s Law con stant was calculated to be 1.97× 10 - 9 atm· m 3 /mol . Thus, linuron is unlikely to volatilize significantl y, and N H Cl Cl O N O C H3 C H3

N

H Cl Cl O N H C H3

N H Cl Cl O N H 2

N H Cl Cl O N H O C H3Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 7 of 20 inhalation via chemical vaporization is unlikely . Linuron is moderatel y persistent with an aerobic soil metabolism half - life ranging from 57 to 100 day s. Because parent linuron is sufficiently persistent and may

be mobile under certain environmental conditions, it has the potential to impact ground water quality. More detailed phy sicochemical properties of the technical grade of linuron are summ arized in Table 3.2 . **Table 3.2.**  **Physicochem ical Properties of the**  **Technical Grade Test Compound Linuron.** Parameter Value Reference Molecular weight (g/mole) 249.1 42213301 Melting point/range 91 - 94± 1°C 42213301 pH 6.98, 7.09 for a 0.2% solution and 9.38, 9.41, for a 2.5% solution at 22.5± 0.5  C 42213301 Density 1.4963 g/mL at 22.3±0.5  C ( air comparison pycnometer) 42213301 Water solubility (20.5 ± 0.5  C) 5.88 × 10 - 3 g/100 mL 42213301 Solvent solubility (20  C) dichloromethane 44.1 g/100 mL toluene 7.91 g/100 mL methanol 12.6 g/100 mL hexane 0.220 g/100 mL 42213301 Vapor pressure at 25°C 4.015×10 - 5 Pa 3.011 ×10 - 7 mm Hg 42213303 Henry’s Law Constant at 25°C 1.97×10 - 9 atm·m 3 /mol http://toxnet.nlm.nih.gov Dissociation constant (pKa) dissociation constant could not be determined; physical and chemical properties deemed all methods in OECD guidelines inappropriate 42213302 Octanol/water partition coefficient Log(KOW) 8.2×10 2 at 23±1  C (GC method) log P ow = 2 .76 42213301 **3.3 Pesticide Use Pattern/** **Directions for Use (860.1200)**  IR - 4 is proposing new uses for the 50% DF formulation Lorox® DF (EPA Reg. No. 61842 - 23). The use directions are summarized below in Table 3.3. **Table 3.3.**  **Summ ary of**  **Proposed Directions for Use of Linuron (Lorox® DF, EPA Reg. No. 61842**  **- 23)**  **.** App lication , Ty pe, and Equip me nt App Rate

(lb ai/A) Timing Max No.

App per Season Max.

Seasonal App Rate (lb ai/A) PHI

(days) Product Use Directions and Limitations **Coriander** Broadcast Ground, Chemigation 0.5 - 1.0

preemergence 1 2.0 East of Rocky Mtns 1.5 West of Rocky Mtns 21 Do not apply by air. Do not apply to sand or loamy

sand soil types to avoid crop injury. Do not use on soils with less than 1% organic matter to avoid crop injury. Do not exceed 4 lbs. LOROX® DF per acre per year East of Rocky Mountains. Do not exceed 3 lbs. LOROX® DF per acre per year West of Rocky Mountains. Additional applications allowed, but do not exceed maximum rate. Do not apply within 155 days of harvest for seed. 0.5 - 1.0 postemergence 2Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 8 of 20 **Dill** Broadcast Ground, Chemigation 1.0

preemergence 1 2.0 East of Rocky Mtns 1.5 West of Rocky Mtns 21 Do not apply by air. Do not apply to sand or loamy

sand soil types to avoid crop injury. Do not use on soils with less than 1% organic matter to avoid crop injury. Do not exceed 4 lbs. LOROX® DF per acre per year East of Rocky Mountains. Do not exceed 3 lbs. LOROX® DF per acre per year West of Rocky Mountains. Additional applications allowed, but do not exceed maximum rate. 0.5 - 1.0 postemergence 2 **Parsley** Broadcast Ground, Chemigation 0.5 - 1.5

preemergence 1 1.5 30 Do not apply by air. Apply after planting, but before the crop emerges. Do not exceed a total of 3 lbs. of LOROX® DF per acre per season. Use lower rates on coarse soils and higher rates on heavier soils. 0.5 postemergence 1 0.5

**Parsley Grown for Seed (Oregon and Washington Only)** Broadcast Ground, Chemigation 0.5 - 1.0

preemergence 2 2.0 NA Do not apply by air. For best results apply preemergence to weeds or early postemergence while weeds are small. Wait at least 21 days between applications. Do not make more than two applications in the first growing season and do not make more than two applications in the second growing season. **Pea (Dry)** Broadcast Ground, Chemigation 1.0

preemergence 1 1.0 NA Do not apply by air. Do not apply to sand or loamy sand soil types. Do not u se on soils with less than 1% organic matter. Apply post planting but preemergence to the crop. Use lower rates on coarse soils and higher rates on heavier soils. **Horseradish** Broadcast Ground, Chemigation 1.5

preemergence 1 1.5 NA Do not apply by air. Apply after planting or during dormancy , but before the leaves emerge in spring. Use lower rates on lighter soils and higher rates on heavier soils. Conclusions : The submitted use directions are adequate to allow evaluation of the residue data relative to the proposed use pattern for coriander, dill, parsley , pea (dry), and horseradish. **4.0 Metabolite/Degradate Residue Profile**  **4.1 Nature of the Residue**  New metabolism data were not submitted to support this registration request. The qualitative nature of the residue in plants and animals is adequately understood. The chemical structures of the metabolites of concern are listed in Table 3.1. Plant metabolism studies show the major plant metabolites to be DCPMU and DCPU . There was a significant amount of unidentified polar components in corn, potato, and soy bean p lant metabolism studies ; however, it was concluded that the components in plants are hydrol yz able to 3,4 - dichloroaniline (3,4 - DCA). There was almost quantitative conversion (via base hydrolysis)Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 9 of 20 of the total radioactive residue (TRR) to 3,4 - DCA in the met abolism studies. In animals, linuron is metabolized to DCPU and hydrox y- norlinuron (through DCPMU and de s methyl - linuron intermediates ) . Sm all amounts of 3,4 - DCA were detected in both the corn and poultry

studies. Water degradates identified in linuron aerobic soil metabolism are the same as the identified plant metabolites. **4. 2**  **Comparison of Metabolic Pathways** The metabolic pathways in plants and livestock are similar. Linuron is converted to DCPMU, DCPU , hydrox y- norlinuron, and unidentified polar metabolites, all of which may be converted to 3,4 - DCA via base hydrolysis.. Metabolism studies also illustrate the distribution of residues of linuron within plant and animals. Radiolabeled 14 C - linuron equivalents were found at the highest levels in the forage or foliage of corn, potato, and so ybean following earl y season soil - directed application of linuron . Detectable residues (0.0 1

– 0.03 ppm) were also found in the potato tuber and corn grain, and quantifiable residues were found in soybean seed. Linuron and/or its metabolites are s ys temic. Inanimals, the highest levels of 14 C - linuron equivalents were found in the liver of both goat and poultry . No intact linuron (<0.001 ppm) was detected in the milk, tissu es, or urine of the test animals , except egg yolk . Approximately 95% of the radioactivity in milk was characterized as polar metabolites . For both livestock and plant commodities, the residues listed in the tolerance expression are the same as those that will be included in the dietary risk assessment, linuron and metab olites convertible to 3,4 - DCA. This essentially encompasses the entire total radioactive residues from plant and livestock metabolism studies. In rats, the major metabolites identified in the urine were hydrox y- norlinuron, DCP U , and DCP MU ; and those in feces were hydrox y- norlinuron and DCPU . The major metabolites DCPU and DCPMU were identified in the rat metabolism study , in both plant and animal metabolism studies, and as water metabolit es in the aerobic soil metabolism study . These metabolites, in addition to desmethyl - linuron, are the metabolites of toxicological concern referenced in the tolerance expression and considered in this risk assessment. Neither hydroxy- 3,4 - dichloroanaline , 3,4 - dichloroanaline nor 3,3',4,4' - tetrachloroazobenzene (TCAB) were present in any of the samples in the rat metabolism study . **4.3 Residues of Concern Summary and Rationale**  D. McNeilly. 11/17/1993. Linuron Plant and Animal Metabolism: Results of the H ED Metabolism Committee Meetings held O c tober 21, and October 29, 1993. MARC Decision Memo. The residue definitions for enforcement of tolerance and for risk assessment are identical, namely , linuron and metabolites convertible to 3,4 - DCA.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 10 of 20 The terminal residues of concern in plants and animals are linuron (parent) and metabolites convertible to 3,4 - DCA including DCPMU, DCPU , desmethyllinuron, and hydrox y- norlinuron. 3,4 - DCA i s not of regulatory concern in connection with the registered use of linuron due to the very low levels at which the chemical is detected in plants and animals (<0.01ppm). M etabolites convertible to 3,4 - DCA are not likely to be more toxic than the parent compound. Linuron can therefore be regulated b y using the enforc ement analy tical method in which known metabolites and unidentified polar components in plants and bound residues in animal tissues are hydrol yz ed to 3,4 - DCA. The total residue convertible to 3,4 - DCA will be compared to the reference dose for parent linuron for purposes of dietary risk assessment. The linuron drinking water exposure assessment is based upon review of environmental fate studies for parent linuron, modeling and monitoring results for parent linuron, and modeling results for the degradates of linuron based upon parent linuron model input parameters. Parent linuron appears to be moderatel y persistent and relatively immobile. Water degradates identified in the linuron aerobic soil metabolism study are desmethyl linuron, DCP MU, and DCPU. Th e degradate 3,4 - DCA was not included in the water assessment as it was not detected in the aerobic soil metabolism study (0.01 ppm detection limit). According to acceptable fate studies, 3,4 - DCA is formed under anaerobic aquatic conditions rarel y found in the environment and is not relevant to drinking water assessment. The environmental fate assessment for linuron is incomplete and tentative because information on the persistence, mobility and dissipation pathway s of several degradates of linuron is not available. However, none of the linuron water degradates are present at levels greater than 10% of the applied parent, and therefore not considered major water metabolites. **Table 4.3 . Summ**  **ary of Metabolites and Degradates to be included in the Risk Assessment and Tolerance**  **Expression** Matrix Residues included in Risk Assessment Residues included in Tolerance Expression Plants Primary Crop linuron and metabolites convertible to 3,4 - DCA linuron and metabolites convertible to 3,4 - DCA Rotational Crop Livestock Ruminant

Poultry Drinking Water Not Applicable **5.0 Residue Profile**  **5.1 Residue Analytical Methods (860.1340)**  Various adequatel y validated anal ytical methods are now available for linuron. For linuron residues of concern in plant commodities , Method ABC - 68406 - M is available and suitable for residue collection as well as enforcement of tolerances. This method has been used previously

for data collection and is used with the current field trial submissions. This method involves re flux of c rop samples in strong base to hydroly ze residues of linuron and its metabolites to 3,4 - DCA. Then, 3,4 - DCA G C/MS . Based on the LLMV from the ILV study , the validated LOQ is 0.01 ppm for linuron and its metabolites hydrol yz able to 3,4 - DCA in/on oily (soy bean seed), watery

(celery), and starch (potato) crop matrices.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 11 of 20 In addition, Method ABC - 65790 was presented. It is a multi - residue m ethod that is suitable for screening for enforcement of tolerances for linuron residues in plant commodities. Itmay also be used as a confirmatory method for Method ABC - 68406. Inthis method, extractions are conducted with methanol and each anal yt e is analyzed by LC/MS/MS . This method separatel y determines residues of linuron and metabolites DCPMU, DCPU , and desmethyl linuron in crop commodities. Based on the LLMV, the validated LOQ is 0.01 ppm each for linuron, DCPMU, DCPU , and desmethyl linuron. Transition ions monitored were: m/z 249 →160 for linuron, m/z 219 →127 for DCPMU, m/z 205→127 for DCPU, and m/z 235→160 for desmethyl linuron. HED notes that this method is not acceptable as the primary enforcement method because of the following reasons: (1) the residue definition contains components in addition to those determined; and (2) the method does not include a secondary ion transition for each analy te, which is required for enforcement methods. For linuron residues of concern in livestock commodities Method, ABC - 67638 - M , is available and suitable for residue collection as well as enforcement of tolerances. This method involves reflux of livestock commodity samples in strong base to hydroly ze residues of linuron and its metabolites to 3,4 - D CA. Then, 3,4 - DCA is anal yzed by G C/MS . Based on the LLMV, the validated LOQ is 0.01 ppm for linuron and its metabolites hydrol yz able to 3,4 - DCA in milk, muscle, and liver. Conclusions. The anal ytical methods , ABC - 68406 - M and ABC - 67638 - M , are adequate for enforcement of the tolerance expression and they been validated . **5. 2**  **Submittal of Analytical Reference Standards (860.**  **1650)** The anal ytical reference standard of linuron at the EPA National Pesticide Standards Repository , expired as of April 18, 2013. The registrant must send an updated COA, or five grams of new material to the Repository as soon as possible. The reference standard can be sent to the Analy tical Chemistry Branch , to the attention of either Theresa Cole or Thuy Nguye n , at the address listed below : USEPA National Pesticide Standards Repository /Anal ytical Chemistry

Branch/OPP 701 Mapes Road Fort George G. Meade, MD 20755 - 5350 The full 9 digit zip code is mandatory or the mail will be returned to the sender. **5. 3**  **Storage Stability (860.1380)** The storage durations and conditions of samples from the submitted crop field trials are presented in Table 5. 3 . Freezer storage stability data were generated concurrently with the crop field trials. Data showed that linuron residues were stable in all matrices under frozen storage for the duration of the storage period.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 12 of 20 **Table 5.3 Stability of Linuron**  **Residues in Following Storage**  **.**

Matrix Storage Tem perature Actual Storage Duration

(days) Interval of Demonstrated

Storage Stability (day s ) Coriander Fresh Leaves and Stems

- 21±7 °C 378 - 514 530 Coriander Dried Leaves and Stems 468 427 Coriander Seed 271 288 Dill Fresh Leaves and Stems 64 - 165 212 D ill Dried Leaves and Stems 164 160 Dill Seed 31 - 128 193 Dill Oil 147 139 Parsley Fresh Leaves and Stems 264 264 Parsley Dried Leaves and Stems 220 220

Pea (Dry) 125 - 138 145 - 147 Horseradish 62 - 70 62 - 70 Conclusions : The storage stability data are adequate to support the storage intervals and conditions for the residue samples of coriander, dill, parsley , pea (dry), and horseradish from the field trials. **5. 4**  **Residue Data 5.4**  **.1 Crop Field Trials (860.1500)**  DER Reference s: MRIDs 48928501, 48928502, 48928503, 48928504, 45633501, 45633502 All of the field trials were conducted according to the proposed label use directions in the appropriate representative geographical regions. Adjuvants were not used in any of the field trials. Residue decline studies were not conducted. **Table 5. 4**  **.1. Summary of Residues from Field Trials with**  **Linuron .**  Crop Matrix Analyte b Applic. Rate (lb ai/acre) PHI

(days) n Residues a ,b (ppm)

Min. Max. HAFT Mean SD **Coriander: Proposed Use =**  **2.0 lb a**  **i/acre total application rate, 21 -**  **day PHI.** Fresh Leaves and Stems Linuron 1.997 - 2.118 19 - 21 8 0.08 1.14 1.055 0.65 0.4 Dried Leaves and Stems 19 1 8.5 NA NA NA Seed 155 2 <0.01 NA NA NA

**Dill: Proposed Use =**  **2.0 lb ai/acre total application rate,**  **21 -**  **day PHI.** Fresh Leaves and Stems Linuron 2.005 - 2.026 20 - 22 7 0.3 0.67 0.56 0.48 0.1 Dried Leaves and Stems 22 2 1.8 3.5 2.65 2.65 1.2 Seed 59 - 85 4 0.06 0.12 0.12 0.09 0.03 Oil 48 1 1.8 NA NA NA **Parsley: Proposed Use =**  **1.5 lb a**  **i/acre total application rate, 30 -**  **day PHI.** Fresh Leaves and Stems Linuron 1.510 29 - 32 4 0.43 1.3 1.02 0.75 0.387 Dried Leaves and Stems 1.511 29 1 2.8 2.8 2.8 NA

**Pea (Dry): Proposed Use =**  **1.0 lb ai/acre total application rate,**  **unspecified PHI.**  Pea (Dry) 0.972 - 1.015 65 - 92 12 <0.01 0.052 0.051 0.014 0.018 **Horseradish :**  **Proposed Use = 1.5**  **lb ai/acre total application rate, unspecified**  **PHI.** Roots Linuron 1. 43

– 1.55 77 - 100 <0.05 NA NA NA a HAFT = highest average field trial. SD = Standard Deviation. For samples with no detectab le residues (< 0.01 ppm) the LOQ value (0.01 ppm) wa s used to calculate the Mean and Standard Deviation. b Residues were converted to and measured as 3,4 - DCA. Values were converted to linuron equivalents.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 13 of 20 Conclusions : The available residue data are acceptable and reflect the proposed use patterns provided in Section B. The number and geographical locations of the field trials are in accordance with the test guidelines. Furthermore, an acceptable method was used for residue quantitation and the data are supported b y adequate storage stability data. **5.4 .2**  **Meat, Milk, Poultry and Eggs (860.1480)**  There are no feed items associated with this current petition. Cowpea commodities would affect the dietary

burden of cattle but since th ey are a bean rather than a pea, they are not included in the petition for dry

peas . D ry

peas onl y includes the following commodities listed under 40 CFR§180.1( g) : Cajanus cajan (inc ludes pigeon pea); Cicerspp. (includes chickpea and garbanzo bean); Lens culinaris (lentil);Pisumspp. (includes dwarf pea, garden pea, green pea, English pea, field pea, and edible pod pea ). Therefore , the previous livestock dietary intake calculations an d resulting tolerance recommendations are not changed. However, since there are livestock feed items associated with field pea, the following restriction should be added to the label: “ Do n ot apply to field pea used for livestock feed.” **5.5 Food Residue**  **Profile** The residue data on coriander, dill, parsley , pea (dry), and horseradish are adequate for tolerance assessment and for use in dietary risk assessment . Based on detectable residues found in forage/foliage of a few metabolism studies, l inuron is a ssumed to have sy stemic activity in plants. Finite residues of linuron and/or its metabolites are anticipated on food and feed comm odities, even from earl y season soil - directed applications. Transfer to l ive stock commodities has been demonstrated, although the residue is primaril y metabolites and unidentified polar components. The anal ytical methods account for the total residue b y conversion of parent, metabolites, and polar , and bound (non - releasable) components to 3,4 - DCA. **6.0 Tolerance**  **Derivation** As shown in Appendix C , the statistical goal of the OECD calculation procedures is to produce an MRLproposal in the region of the 95 th percentile of the underl ying residues distribution. Coriander (MRID 48928501) The dataset used to establish a tolerance for linuron consisted of field trial data on coriander representing two applications within - 5% to +10% of 1 lb ai/A per application for a total of 2 lb ai/A per crop, and 19 - to 2 1 - day PHI s . The average residue values used to calculate the tolerance are provided below. Combined residues of linuron and its metabolites hydrol yz ed to 2,4 - DCA were quantifiable (LOQ = 0.01 ppm ) in/on samples . Data from f our field trials were used in the OECD tolerance calculation procedures f or fresh coriander, resulting in a recommended tolerance of 1.5 ppm . For dried coriander, a 9X concentration factor was derived from a single residue field trial where the coriander was dried, resulting in a recommended to lerance of 1 0 ppm (calculated by : HAFT of fresh coriander residue 1.055 ppm × concentration factor 9 ). For coriander seed, no detectable residues were found, resulting in a recommended tolerance of 0.05 ppm (calculated b y: 5 × LOQ 0.01 ppm) .Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 14 of 20 Dill (MRID 4 8928502) The dataset used to establish a tolerance for linuron consisted of field trial data on dill representing two applications within - 5% to +10% of 1 lb ai/A per application for a total of 2 lb ai/A per crop, and 20 - to 22 - day PHI s . The average residue values used to calculate the tolerance are provided below. Combined residues of linuron and its metabolites hydrol yz ed to 3 ,4 - DCA were quantifiable ( LOQ = 0.01 ppm) in/on all samples. Data from three field trials were used in the OE CD tolerance calculation procedures f or fresh dill , resulting in a recommended tolerance of 0.6 ppm. For dried dill , a 4.73 X concentration factor was derived from a single residue field trial where the dill was dried, resulting in a recommended tolerance of 3.0 ppm ( calculated b y : HAFT of fresh dill 0.56 ppm × concentration factor 4.73 ) . For dill seed, the OECD calculation procedures could not be used because there were only two field trials, thus resulting in a recommended tolerance of 0.5 ppm (calculate d by : 5 × mean dill oil residue 0.9 ppm) . For dill oil, a 3.21X concentration factor was derived from a single residue field trial, resulting in a recommended tolerance of 2.0 ppm (calculated b y : HAFT of fresh dill 0.56 ppm × concentration factor 3.21) . Parsley (MRID 48928503) The dataset used to establish a tolerance for linuron consisted of field trial data on parsley representing one application of 1.51 lb ai/A and 29 - to 32 - day PHIs. The average residue values used to calculate the tolerance are prov ided below. Although the LOQ were not statistically calculated in this study , all c ombined residues of linuron and its metabolites hydrol yz ed to 2,4 - DCA were quantifiable in/on samples above the LLMV (0.05 ppm) . For fresh parsley , the OECD calculation procedures could not be used because there were only two field trials, thus resulting in a recommended tolerance of 4.0 ppm (calculated b y: 5 × mean fresh parsley residue 0.75 ppm). For fresh parsley , the recommended tolerance is 4.0 ppm. For dried parsley , a 2.76 X concentration factor was derived from a single residue field trial where parsley was dried, resulting in a recommended tolerance of 3.0 ppm ( calculated b y: HAFT of fresh parsley 1.015 ppm × concentration factor 2.76) . Pea (Dry) (MRID 48928504) The dataset used to establish a tolerance for linuron consisted of field trial data on peas (dry) representing one application within - 5% to +10% of 1 lb ai/A, and 65 - to 92 - day PHIs. The average residue values used to calculate the tolerance are provided below. Combined residues of linuron and its metabolites hydrolyzed to 2,4 - DCA were quantifiable in/on two of six trials. Data from all six field trials were used in the OECD calculation procedures, resulting in a recommended tolerance of 0. 0 6 ppm. Horseradish (MRIDs 45633501 and 45633502) The dataset used to establish a tolerance for linuron consisted of field trial data on horseradish representing one application within - 5% to +10% of 1.5 lb ai/A per application , and 76 - to 1 00 - day PHI s. The avera ge residue values used to calculate the tolerance are provided below. An LOQ was not statistically calculated in this study , but the LLMV was determined to be 0.05 ppm. Data from three field trials indicated that detectable residues were not found. Thus , data consisting of <LOQ values from three field trials were used in the OECD tolerance calculation procedures, resulting in a recommended tolerance equivalent to the LOQ of 0.0 5 ppm.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 15 of 20 **Appendix A. Summary of Submitted Residue Chemistry Studies**  **Table A1 .**  **Summary of Submitted Residue Chemistry Studies** OCSPP Guideline MRID Title

860.1340 Residue Analytical Method 48832101 Determination of the Substituted Urea Herbicide Linuron and its Metabolites in Oily,

Watery, and Starch Crop Matrices 48832102 Independent Laboratory Validation of “Determination of the Substituted Urea Herbicide

Linuron and its Metabolites in Soil and Agricultural Products” for Oily, Watery, and Starch Crop Matrices 48832103 Determination of the Substituted Urea Herbicide Linuron and its Metabolites in Animal

Tissue 48832104 Independent Laboratory Validation of the Draft Method “Determination of the Substituted

Urea Herbicide Linuron and its Metabolites in Animal Tissues” 48832105 Method Transfer and Validation of “Determination of the Substituted Urea Herbicide

Linuron and its Metabolites in Soil and Agricultural Products” for Animal Matrices 48832106 Analytical Method for the Determination of Linuron and Metabolites in Crops using

LC/MS/MS 48832107 Independent Laboratory Validation of “Determination of the Substituted Urea Herbicide

Linuron and its Metabolites in Soil and Agricultural Products” for Oily, Watery, and Starch Crop Matrices 48832108 Independent Laboratory Validation of Residue Analytical Method 20 001407/01 - RVP,

“Residue Analysis of Diuron and Metabolites in Plants Method Validation” for the Determination of Residues of Linuron and Metabolites in Grapes, Olives, and Wheat Grain 48832109 Analytical Method for the Determination of Linuron and Metabo lites in Animal Tissue

using LC/MS/MS 48832110 Independent Laboratory Validation of “Analytical Method for the Determination of Linuron

and Metabolites in Animal Tissue using LC/MS/MS” and “Analytical Method for the Determination of Diuron and Metabolite s in Animal Tissue using LC/MS/MS”

860.1500 Crop Field Trial 48928501 Linuron: Magnitude of the Residue on Coriander 48928502 Linuron: Magnitude of the Residue on Dill 48928503 Linuron: Magnitude of the Residue on Parsley 48928504 Linuron: Magnitude of the Residue on Pea (Dry) 45633501 45633502 Linuron: Magnitude of the Residue on HorseradishLinuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 16 of 20 **Appendix B**  **. International Residue Limits Table for Linuron**  **Table B1. Summary of US and International Tolerances and Maxim**  **um Residue Limits**  **of Linuron**  Residue Definition US Canada Mexico b Codex 40 CFR 180.184: Plant and Livestock: (3 - (3,4 - dichlorophenyl) - 1 - methoxy - 1 - methylurea) and its metabolites convertible to 3,4 - dichloroaniline None None

Commodity a Tolerance (ppm) /Maximum Residue Limit (mg/kg) US Canada Mexico b Codex Cilantro, fresh leaves 1.5 Cilantro, dried leaves 10 Coriander, seed 0.05 Dillweed, fresh leaves 0.6 Dillweed, dried leaves 3.0 Dill, seed 0.5 Dill, oil 2.0 Horseradish 0. 05 Parsley, leaves 4.0 Parsley, dried leaves 3.0 Pea, dry, seed 0.06 Com pleted: M. Negussie; 07/30/2013 a Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and not those proposed by the applicant. b M exico adopts US tolerances and/or Codex MRLs for its export purposes.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 17 of 20 **A ppendix**  **C .**  **OECD MRL Calculation Procedure Inputs/Outputs**  Coriander (MRID 48928501 ) 2.0 lb ai/A; 19 - 2 1 day

PHI s **Residues (mg/kg)** 0.940 4.000 0.086 4.000 0.525 4.000 1.055 4.000 **Compound Linuron**  **Crop Fresh Coriander**  **Region / Country CA/OR/TN/TX**  **GAP Total number of data (n)**  4 **Percentage of censored data** 100% **Number of non -**  **censored data** 0 **Lowest residue** 0.086 **Highest residue** 1.055 **Median residue** 0.733 **Mean** 0.651 **Standard deviation (SD)** 0.441 **Correction factor for censoring (CF)**  0.333 **Proposed MRL estimate**

**- Highest residue**  1.055

**- Mean + 4 SD**  2.414

**- CF x 3 Mean**  0.651 **Unrounded MRL** 1.055 **Rounded MRL 1.5**  High uncertainty of MRL estimate due to small dataset and high level of censoring.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 18 of 20 Dill (MRID 48928502 ) 2.0 lb ai/A; 20 - 2 2 day

PHI s **Residues (mg/kg)** 0.335 3.000 0.490 3.000 0.560 3.000 **Compound Linuron**  **Crop Fresh Dill**  **Region / Country CA/FL/WA**  **GAP Total number of data (n)**  3 **Percentage of censored data** 100% **Number of non -**  **censored data** 0 **Lowest residue** 0.335 **Highest residue** 0.560 **Median residue** 0.490 **Mean** 0.462 **Standard deviation (SD)** 0.115 **Correction factor for censoring (CF)**  0.333 **Proposed MRL estimate**

**- Highest residue**  0.560

**- Mean + 4 SD**  0.922

**- CF x 3 Mean**  0.462 **Unrounded MRL** 0.560 **Rounded MRL 0.6**  H igh uncertainty of MRL estimate due to small dataset and high level of censoring.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 19 of 20 Pea (Dry) (MRID 4892850 4 ) 1 .0 lb ai/A; 65 - 92 day

PHI s **Residues (mg/kg)** 0.015 6.000 0.010 * 0.010 * 0.010 * 0.051 6.000 0.010 * **Compound Linuron**  **Crop Pea (Dry)**  **Region / Country ID/ND/WA**  **GAP Total number of data (n)**  6 **Percentage of censored data** 100% **Number of non -**  **censored data** 0 **Lowest residue** 0.010 **Highest residue** 0.051 **Median residue** 0.010 **Mean** 0.018 **Standard deviation (SD)** 0.016 **Correction factor for censoring (CF)**  0.333 **Proposed MRL estimate**

**- Highest residue**  0.051

**- Mean + 4 SD**  0.083

**- CF x 3 Mean**  0.018 **Unrounded MRL** 0.051 **Rounded MRL 0.06**  High uncertainty of MRL estimate due to small dataset and high level of censoring.Linuron Summary of Analytical Chemistry and Residue Data Barcode D404359

Page 20 of 20 Horeseradish (MRID s 45633501 and 45633502 ) 1.5 lb ai/A; 76 - 100 day

PHI s **Residues (mg/kg)** <0.05 <0.05 <0.05 **Compound Linuron**  **Crop Horseradish**  **Region / Country MD/WI/NJ**  **GAP Total number of data (n)**  3 **Percentage of censored data** 10 0% **Number of non -**  **censored data** 0 **Lowest residue**  0. 050 **Highest residue** 0. 050 **Median residue** 0.050 **Mean** 0. 050 **Standard deviation (SD)** 0. 000 **Correction factor for censoring (CF)**  0.333 **Proposed MRL estimate**

**- Highest residue**  0. 050

**- Mean + 4 SD**  0. 050

**- CF x 3 Mean**  0 . 050 **Unrounded MRL** 0 . 05 **Rounded MRL 0**  **. 0**  **5** High uncertainty of MR L estimate due to small dataset and high level of censoring .