Page 1 of 11 **UNITED STA**

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

**POLLUTION PREVENTION MEMORANDUM**  Date: 1 7 - December
- 2013 Subject: **Addendum to**  **DP Barcodes D404359 and**  **D411652 :**  **Linuron**
. Petition for the

Establishment of Permanent Tolerances and Registration for Use on Coriander, Dill, Parsley, Pea (Dry), and Horseradish ; and Submission of Residue Analytical Methods of Plants and Animal Matrices
. Summary of Analy tical Chemistry

and Residue Data. PC Code: 035506 DP Barcode s : D 416651 Decision No.: 469722 Registration No. : 61842
- 23 Petition No.: 2E8083 Regulatory Action: Section 3 Risk Assessment Ty

pe: NA Case No.: NA TXR No.: NA CAS No.: 330
- 55 - 2 MRID No.: NA 40 CFR : §180.184 From: Nancy

Tsaur, Chemist Risk Assessment Branch 3 (RAB3) Health Effects Division (7509P) Through: Christine Olinger, Branch Chief

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) and Laura Nollen/Barbara Madden , RM05 Risk Integration Minor Use and Emergency Response Branch (RIMUERB) Registration D ivision (7505P) This document serves as an addendum to the original residue data review from August 14, 2013. The addendum updates corrected values for the recommended tolerances , tolerance derivation, and input/output values for the Organization for Ec onomic Cooperation and Development ( OECD) tolerance calculation procedures
.Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 2 of 11 **Table of Contents** 1.0 Executive Summary
................................ ................................ ................................ ............ 3 2.0 Regulatory

Recommendations
................................ ................................ ............................ 3 2.1 Tolerance Considerations
................................ ................................ ................................ . 3 2.1.1 Recommended Tolerances
................................ ................................ ........................ 3 2.1.2 Revisions to Petitioned
- For Tolerances
................................ ................................ .... 4 2.1.3 International Harmonization
................................ ................................ ..................... 4 3.0 Residue Data: Crop Field Trials (860.1500)
................................ ................................ .... 4 4.0 Tolerance Derivation
................................ ................................ ................................ .......... 5 Appendix A. OECD MRL Calculation Procedure Inputs/Outputs
................................ ................ 8Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 3 of 11 **1.0 Executive Summary**  The 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 formul ations, 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. **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 are submitted , there are no residue chemistry deficiencies that would preclude granting Section 3 registration for the requested crop commodity uses of linuron , or estab lishment of tolerances for residues of linuron
. The specific tolerance recommendations are discussed in Section 2 .1
. 1
. **2. 1**  **Tolerance Considerations 2.**  **1 .**  **1 Recommended Tolerances**  In addition to the recommended tolerances listed below in Table 1 , the tolerance with regional registration under 40 CFR § 180.184(c) for parsley, leaves (0.25 ppm) should be deleted. **Table 1**  **. Tolerance Summary for Linuron**  **.** Commodity Proposed

Tolerance (ppm) HED - Recommended Tolerance (ppm) Comments a ( OECD calculation adjus t ments to tolerances) DP404359 DP416651 Cilantro, fresh leaves 3.0 1.5 3.0 Corrected OECD Calculation Procedure values Cilantro, dried leaves 27 10 10 9X PF × HAFT of 1.055 ppm Coriander, seed 0.01 0.05 0. 01 LOQ of 0.01 ppm Dillweed, fresh leaves 1.5 0.6 1.5 Corrected OECD Calculation Procedure values Dillweed, dried leaves 7.1 3.0 5 .0 9X PF × HAFT of 0.56 ppm Dill, seed 0.3 0.5 0.5 5 × Mean of 0.09 ppm Dill, oil 4.8 2.0 2 .0 3.21 PF × HAFT of 0.56 ppm Horseradish 0.05 0.05 0.05 LOQ of 0.05 ppm Parsley, leaves 3.0 4.0 4 .0 5 × Mean of 0.75 ppm Parsley, dried leaves 8.3 3.0 9.0 9X PF × HAFT of 1.015 ppm Pea, dry, seed 0.08 0.06 0.09 Corrected OECD Calculation Procedure values a OECD = Organization for Economic Cooperation and Development
. PF = processing factor. HAFT = highest average field trial
. LOQ = limit of quantitation.Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 4 of 11 **2.1 .**  **2 Revisions to Petitioned**  **- For Tolerances**  All of the petitioned
- for tolerance level s (except for fresh cilantro, coriander seed, fresh dillweed, and 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 (DCA) , 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, the tolerance level for pea, dry, seed should be increased
. 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 two commodities: dill, seed; and parsley, leaves. Based on this calculation method, both tolerance levels should be increased. For the dried herbs (cilantro, dillweed, and parsley) , the formula of the highest average field trial (HAFT) multiplied by

the herb processing (drying) factor o f 9X was used to calculate the recommended tolerance levels (the processing factor was derived from dividing the average dried cilantro commodity residue b y the average fresh cilantro residue). Based on this calculation method, the tolerance levels for dried cilantro and dillweed should be decreased , and the tolerance for dried parsley should be increased
. For dill oil, the formula of the HAFT multiplied by the herb processing (oil extraction) factor of 3.21X was used to calculate the recommended tolerance level (the processing factor was derived from dividing the average dill oil commodity residue by

the average fresh dill residue) . Based on this calculation method, the dill oil tolerance should be decreased. **2. 1**  **. 3**  **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 established for linuron. Therefore, there are no harmonization issues that exist with respect to U.S. tolerances. **3.0 Residue Data**  **: Crop Field Trials (860.1500)**  DER References: 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. The available residue data , as shown in Table 2, 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.Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 5 of 11 **Table 2**  **. Summary of R esidues from** **Field Trials with Linuron.** Crop Matrix Analyteb Applic. Rate (lb ai/acre) PHI

(days) n Residues a,b (ppm)

Min. Max. HAFT Mean SD **Coriander: Proposed Use = 2.0 lb ai/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 ai/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 3 <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. **4 .0**  **Tolerance Derivation**  As shown in Appendix A , the statistical goal of the OECD calculation procedures is to produce an MRL/tolerance proposal in the region of the 95 th percentile of the underlying 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 be low. Combined residues of linuron and its metabolites hydrol yz ed to 3 ,4
- DCA were quantifiable (LOQ = 0.01 ppm) in/on samples
. **For fresh coriander** , data from f our field trials were used in the OECD tolerance calculation procedures f

or fresh coriander, resulting in a recommended tolerance of **3.0 ppm**  . (Note that the correct commodity

term is cilantro, fresh leaves). **For dried coriander** , a 9X concentration factor was derived from a single residue field trial where the coriander was dried (calculated b y dividing the average dried cilantro commodity residue b y the average fresh cilantro residue) , resulting in a recommended tolerance of **1 0**  **ppm** (calculated b y: HAFT of fresh coriander residue 1.055 ppm × processing factor 9 ). (Note that the c orrect commodity

term is cilantro, dried leaves). **For coriander seed** , no detectable residues were found, resulting in a recommended tolerance of **0.0 1**  **ppm** ( at the LOQ 0.01 ppm)
.Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 6 of 11 Dill (MRID 48928502) 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. C ombined residues of linuron and its metabolites hydrol yz ed to 3 ,4
- DCA were quantifiable ( LOQ = 0.01 ppm) in/on all samples. **For fresh dill** , data from three field trials were used in the OECD tolerance calculation procedures f

or fresh dill , resulting in a recommended tolerance of **1.5 ppm**  . **For dried dill**  , the 9 X processing factor derived for coriander was used , resulting in a recommended tolerance of **5 .0**  **ppm** ( calculated by : HAFT of fresh dill 0.56 ppm × concentration factor 9 )
. Since all fresh herbs contain comparable water content, the processing factor for dried herbs should be the same. By using the highest processing factor value derived from coriander (at 9X), HED is being sufficiently protective that the residues of linuron are not underestimated in dried herb commodities. **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** (calculated by : 5 × mean dill oil residue 0. 0 9 ppm)
. **For dill oil** , a 3.21X concentration factor was derived from a single residue field trial (calculated by dividing the average dill oil commodity residue by

the average fresh dill residue) , resulting in a recommended tolerance of **2.0 ppm**  (calcul ated by : HAFT of fresh dill 0.56 ppm × concentration factor 3.21)
. 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 100
- day PHI s. The average residue values used to calculate the to lerance are provided below. An LOQ was not statistically calculated in this study, but the Lowest Limit of Method Validation ( LLMV) was determined to be 0.05 ppm. **For horseradish** , 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 **0.05 ppm**  . 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 provided below. Although the LOQ were not statistically calculated in this study, all c ombined residues of linuron and its metabolites hydrol yz ed to 3 ,4
- DCA were quantifiable in/on samples above the LLMV (0.05 ppm)
.Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 7 of 11 **For fresh parsley** , the OECD calculation procedures could not be us ed because there were onl y two field trials, thus resulting in a recommended tolerance of **4.0 ppm** (calculated by : 5 × mean fresh parsley

residue 0.75 ppm). **For dried parsley**  , the 9X processing factor derived for coriander was used , resulting in a recommended tolerance of **9 .0**  **ppm** ( calculated by: HAFT of fresh parsley 1.015 ppm × concentration factor 9 )
. Since all fresh herbs contain comparable water content, the processing factor for dried herbs should be the same. By using the highest processing factor value derived from coriander (at 9X), HED is being sufficiently protective that the residues of linuron are not underestimated in dried herb commodities. 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 3 ,4
- DCA were quantifiable in/on two of six trials. **For dry peas** , data from all six field trials were used in the OECD calculation procedures, resulting in a recommended tolerance of **0. 0**  **9 ppm**  .Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 8 of 11 **A ppendix**  **A .**  **OECD MRL Calculation Procedure Inputs/Outputs**  Coriander (MRID 48928501 ) (Cilantro, Fresh) 2.0 lb ai/A; 19
- 2 1 day

PHI s **Residues (mg/kg)** 0.940 1 0.086 1 0.525 1 1.055 1 **Compound Linuron**  **Crop Fresh Coriander**  **Region / Country CA/OR/TN/TX**  **GAP Total number of data (n)**  4 **Percentage of censored data** 0% **Number of non -**  **censored data** 4 **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)**  1.000 **Proposed MRL estimate**

**- Highest residue**  1.055

**- Mean + 4 SD**  2.414

**- CF x 3 Mean**  1.954 **Unrounded MRL** 2.414 **Rounded MRL 3**  High uncertainty of MRL estimate due to small dataset.Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 9 of 11 Dill (MRID 48928502 ) 2.0 lb ai/A; 20
- 2 2 day

PHI s **Residues (mg/kg)** 0.335 1 0.490 1 0.560 1 **Compound Linuron**  **Crop Fresh Dill**  **Region / Country CA/FL/WA**  **GAP Total number of data (n)**  3 **Percentage of censored data** 0% **Number of non -**  **censored data** 3 **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)**  1.000 **Proposed MRL estimate**

**- Highest residue**  0.560

**- Mean + 4 SD**  0.922

**- CF x 3 Mean**  1.385 **Unrounded MRL** 1.385 **Rounded MRL 1.5** 
H igh uncertainty of MRL esti mat e due to s mall dataset .Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 10 of 11 Pea (Dry) (MRID 4892850 4 ) 1 .0 lb ai/A; 65
- 92 day

PHI s **Residues (mg/kg)** 0.015 1 0.010 * 0.010 * 0.010 * 0.051 1 0.010 * **Compound Linuron**  **Crop Pea (Dry)**  **Region / Country ID/ND/WA**  **GAP Total number of data (n)**  6 **Percentage of censored data** 67 % **Number of non -**  **censored data** 2 **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. 556 **Proposed MRL estimate**

**- Highest residue**  0.051

**- Mean + 4 SD**  0.083

**- CF x 3 Mean**  0.0 29 **Unrounded MRL** 0.0 83 **Rounded MRL 0.**  **09** High uncertainty of MRL estimate due to small dataset and high level of censoring.Linuron Summary of Analytical Chemistry and Residue Data Barcode D416651

Page 11 of 11 Hors eradish (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 0 **Rounded MRL 0**  **. 0**  **5** High uncertainty of MR L estimate due to small dataset and high level of censoring .