### Page 1 of 5 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 **OFFICE OF CHEMICA** **L SA FETY**  **AND POLLUTION PREVENTION**  

### MEMORANDUM Date: **March 25**  **, 2011** SUBJECT: **Tetrachlorvinphos .**  Response to Comment on Storage Stability Residue Data Deficiencie s. **PC Code:** 0 837 01 /083702 **DP Barcode s**  **:** D385359 & D3 86954 **Decision No.:** 35 9967 **Registration No. :**  Not Applicable **Petition No.:** Not Applicable **Regulatory Action:** Reregistration Follow-up **Risk Assessment Type:** Not Applicable **Case No.:** 0 321 T**XR No.:** Not Applicable **CAS No.:** 22248 - 79 - 9 **MRID No s**  **.:** 486378101 48319001 **40 CFR:** 180. 2 52 

### FROM: Christine L . Olinger, Chemist

Risk Assessment Branch VII Health Effects Division (7509P) Office of Pesticide Programs THRU: Donna S. Davis, Chemist

Michael S. Metzger, Chief, Risk Assessment Branch VII Health Effects Division (7509P) Office of Pesticide Programs TO: James Parker, CRM

Risk Management and Implementation Branch II Pesticide Re - evaluation Division (7508P) Office of Pesticide Programs In response to deficiencies noted in a review of livestock magnitude of residue studies (C. Olinger; 10/7/10; D320848, D320858, D320859, and D 381350 ) SRA International , on behalf of KMG Bernuth, has submitted data relating to the storage stability of tetrachlorvinphos residues in livestock tissues , eggs, and milk. The Pesticide Re - evaluation Division (PRD) has requested HED review of this information to satisfy the outstanding data deficiencies. **CONCLUSIONS** No additional storage stability data are needed to support the use of tetrachlorvinphos on poultry . The magnitude of residue study on poultry

is adequate and there are no outstanding deficiencies with this study. The magnitude of residue requirement is considered satisfied for poultry .

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No storage stability

data are available for livestock commodities. The samples from the ruminant magnitude of residue study that reflect the maximum current use pattern were stored less than thirty

days, so storage stability data are not needed. Provided the registrant does not make changes to the current use pattern/application rates , no additional storage stability data are needed and the requirement for a magnitude of residue study for ruminants is satisfied. S hould the registrant wish to revise the existing use patterns such that the magnitude of residue data from other treatment groups would be used for tolerance and/or risk assessment , additional storage stability data demonstrating stabil ity of tetrachlorvinphos and its metabolites for at least two months would be required. **DETAILED CONSIDERATIONS** HED identified the following deficiencies regarding the storage stability data as well as detailed information on storage intervals in the review of poultry and ruminant magnitude of residue studies (C. Olinger; 10/7/10; D320848, D320858, D320859, and D 381350 ) .  New storage stability

studies should be conducted with quantifiable ( i.e., fortified) residues of all analytes in all cattle and p oultry matrices. In addition, the registrant needs to submit information pertaining to dates of treatment, collection, extraction, and analys is to verify the maximum storage intervals of all samples collected from both the cattle and poultry studies.  Although a companion storage stability study was included in support of the cattle study, the submitted data were deemed inadequate because of the study design. S elected samples of various matrices were re - assayed after the initial analysis. Considerable degradation may

have occurred prior to the initial analys is of storage stability samples. Many of the matrices did not have quantifiable residues of one or more of the anal ytes at the time of initial analysis, so potential degradation upon storage cannot be accurately assessed. SRA International, on behalf of KMG Bernuth, has submitted additional information on the storage intervals for these studies, which is discussed below. Data Submitted to Support MRID 47589301 Poultry Magnitude of Residue Study The registrant has provided information on the storage intervals for samples from the original poultry study . SRA submitted storage interval information in two volumes, MRID Nos. 486378101 and 48319001 . A summary of the storage intervals is presented in Tabl e 1 below. **Table 1 . Storage Intervals for Sam** **ples from Tetrachlorvinphos Poultry Magnitude of Residue Study**  **1 Matrix**  **Group(s) 2**  **Time Interval**  **3 No. Days** 

**Storage Matrix**  **Group(s) 2**  **Time Interval**  **3 No. Days** 

**Storage** Eggs 1 -4 - 7 1 - 3 Eggs 1 -4 78 11 Eggs 1 -4 - 1 1 - 2 Eggs 1 -4 82 9 Eggs 1 -4 1 2 - 3 Eggs 1 -4 84 12 - 20 Eggs 1 -4 3 2 - 3 Eggs 1 -4 86 18 Eggs 1 -4 5 2 - 3 Eggs 1 -4 88 16 Eggs 1 -4 8 1 - 3 Eggs 1 -4 91 13

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**Table 1 . Storage Intervals for Sam** **ples from Tetrachlorvinphos Poultry Magnitude of Residue Study**  **1 Matrix**  **Group(s) 2**  **Time Interval**  **3 No. Days** 

**Storage Matrix**  **Group(s) 2**  **Time Interval**  **3 No. Days** 

**Storage** Eggs 1 -4 12 2 Eggs 1 -4 95 15 Eggs 1 -4 15 2 - 4 Eggs 1 -4 98 12 Eggs 1 -4 17 2 - 4 Eggs 1 -4 101 9 Eggs 1 -4 19 2 - 4 Eggs 1 -4 105 5 Eggs 1 -4 22 1 - 4 Muscle 1 -4 0 14 Eggs 1 -4 26 2 Muscle 3R 7 22 Eggs 1 -4 29 2 - 4 Muscle 3R 14 15 Eggs 1 -4 31 3 - 4 Muscle 3R 21 8 Eggs 1 -4 33 3 - 4 Liver 1 -4 0 18 Eggs 1 -4 36 1 - 4 Liver 3R 7 22 Eggs 1 -4 40 2 Liver 3R 14 15 Eggs 1 -4 43 2 - 6 Liver 3R 21 8 Eggs 1 -4 45 3 - 10 Kidney 1 -4 0 27 Eggs 1 -4 47 3 - 10 Kidney 3R 7 22 Eggs 1 -4 50 1 - 19 Kidney 3R 14 15 Eggs 1 -4 54 2 - 17 Kidney 3R 21 8 Eggs 1 -4 57 4 - 6 Skin/Fat 1 -4 0 20 Eggs 1 -4 59 4 - 10 Skin/Fat 3R 7 26 Eggs 1 -4 61 6 - 10 Skin/Fat 3R 14 19 Eggs 1 -4 64 11 - 19 Skin/Fat 3R 21 12 Eggs 1 -4 68 9 - 17 Abdominal Fat 1 -4 0 25 Eggs 1 -4 70 12 Abdominal Fat 3R 7 26 Eggs 1 -4 71 4 - 11 Abdominal Fat 3R 14 19 Eggs 1 -4 73 4 Abdominal Fat 3R 21 12 Eggs 1 -4 75 6 1 MRID No. for poultry magnitude of residue study is MRID 47589301; storage intervals are reported in MRID Nos. 48 378101 48319001. 2 Groups are described in MRID 47589301. 3 Time interval s for eggs are days after study initiation. Negative numbers refer to num ber of days prior to first application. Time interval s for tissues refer to days after sacrifice. 

### The Agency

generall y requires storage stability data when samples from magnitude of residue studies are stored for more than 30 days. Since all samples were stored for less than 30 days, no storage stability

data are needed to support the poultry magnitude of residue study . There are no outstanding deficiencies for the poultry magnitude of residue study and the magnitude of residue requirement for poultry

has been satisfied. Data Submitted to Support MRID 47193001 Ruminant Magnitude of Residue Study The registrant provided storage intervals for the samples from the original ruminant study. In addition , the registrant submitted an inadequate storage sta bility study to support the ruminant magnitude of resi due study . In response to the deficiencies identified in the October 2010 review the registrant submitted detailed information on storage intervals from the magnitude of residue study (MRID Number pending). The magnitude of residue study included five different treatment groups, which are described in Table 2 below. Treatment group 4 represents the current maximum label rate for both the feedthrough and dermal treatment uses. A summary of the storage intervals from treatment group 4 is presented in Table 3 below.

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**Table 2. Summary of Treatment Groups from Ruminant Magnitude of Residue Study**  **Group Treatm** **ent Description** 1 Control 2 Nominal 1x rate Oral Only 3 Nominal 1x rate Oral; Nominal 0.5x rate Dermal 4 Nominal 1x rate Oral; Nominal 1x rate Dermal 5 Nominal 3x rate Oral; Nominal 0.5x rate Dermal **Table 3**  **. Storage Intervals for Sam** **ples from Tetrachlorvinphos**  **Rum inant**  **Magnitude of Residue Study (Group 4 Only)**  **1 Matrix**  **Cow N o.**  **2 Time**  **Interval (Days)**  **3 No. Days** 

**Storage** Milk 8 - 10 - 7 9 Milk 8 - 10 - 1 3 Milk 8 - 10 1 6 Milk 8 - 10 2 7 Milk 8 - 10 4 16 Milk 8 - 10 7 26 Milk 8 - 10 10 20 Milk 8 - 10 14 9 Milk 8 - 10 17 8 Milk 8 - 10 21 7 Milk 8 - 10 24 11 Milk 8 - 10 28 14 Skim Milk 8 - 10 14 25 Skim Milk 8 - 10 29 15 Cream 8 - 10 14 23 Cream 8 - 10 29 22 Muscle 8 0 23 (63) 4 Muscle 9 0 22 (62) Muscle 10 0 21 (61) Peritoneal Fat 8 0 28 Peritoneal Fat 9 0 27 Peritoneal Fat 10 0 26 Subcutaneous Fat 8 0 23 (63) Subcutaneous Fat 9 0 22 (62) Subcutaneous Fat 10 0 21 (61) Kidney 8 0 31 Kidney 9 0 30 Kidney 10 0 29 Liver 8 0 34 Liver 9 0 33 Liver 10 0 32 1 MRID No. for ruminant magnitude of residue study is MRID 47 1 930 0 1; storage intervals are reported in email sent 3/23/11; MRID number pending . 2 Cow identification numbers are described in MRID 47 1 930 0 1. 3 Time interval s for milk are days after study initiation. Negative numbers refer to number of days prior to first application. Time interval for tissues refers to days after sacrifice . 4 Number of days storage prior to TCPEdiol analysis (where different from other analytes) is shown in parentheses

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The samples from treatment group 4 represent the application rates and retreatment intervals that represent current product labels. Almost all samples were analyz ed within 30 days; all were anal y zed within 34 days with the exception of the anal ys es for one metabolite, TCPEdiol, in muscle and subcutaneous fat. HED does not need additional storage stability data to support this treatment grou

p since samples were anal yz ed within 30 days or slightl y later. Although some samples were analyz ed for one metabolite after two months of storage, most samples were anal yz ed within an appropriate interval for this metabolite and residues were non- detecta ble. Since significant exposure is not expected, a storage stability study for this metabolite will not be required to support treatment group 4. However, samples from other treatment groups were stored up to two months. The data from these groups have not been used directly in tolerance and/or risk assessment, but have only been used for risk characterization. S hould the registrant amend use directions such that these data would be needed for tolerance assessment, storage stability data would be required.