### UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460



### Date: October 22, 2013 OFF I CE OF CHEMICAL SAFETY AND POLLUTI ON PREVENTION



### SUBJECT: Quizalofop Ethyl and Quizalofop-P-Ethyl, Response to Comments on the Human Healt h Risk Assessment for Registration Review.

PC Codes: 128709, 128711 Decision No.: 482484 Petition No.: NA Risk Assessment T ype: NA TXRNo.: N A MRIDNo.:NA DP Barcode: 0414555 Registration No.: NA Regulatory Action: Registration Review Case No.: NA CAS Nos.: 76578-14-8 , 100646-51-3 40 CFR: § 180.441



### FROM: Danette Drew, Chemist /Risk Asses......._

- Ideliz Negron-Encarnacion, Ph.D. , Chemist Risk Assessment Branch V /VII Health Effects Division (7509P) Office of Pesticide Programs


### THROUGH: Michael Metzger, Branch Chie{ } 

# J 

# J) , Risk Assessment Branch V 

# Nit'{ M · Health Effects Division (7509P) Office of Pesticide Programs 

### TO: Khue Nguyen, Chemical Review Manager Risk Management and Implementation Branch 1 Pesticide Re-Evaluation Division (7508P)

E.l. du Pont de Nemours & Company (DuPont Crop Protection) has submitted comments on the Health Effect's Di v ision (HED) document titled Quizalofop Ethyl and Quizalofop

-P-Ethyl , Summary of Human Health RiskAssessment.for Registration Review ( 12 /12/12; D394192). Those comments pertain to the residue chemistry data requirements as found on p.9 of D394192. In the present memo, each chemistry deficiency is briefly summarized, followed by DuPont' s comments (from their submission dated 5/20/13, DuPont Crop Protection Comments to Federal Register/Vol. 78 , No.54/Wednesday, March 20, 2013, Pages 17201-17204; Quizalofop Registration Review, Case N o. 7215, Pesticide Docket Identification No. EPA-HQ-OPP-2007- 

### 1089; No 

### MRID No.) and the current 

### HED response.
Page 1 of 4Residue Chemistry Deficiency 

### 1) Directions for Use (860.1200): The Section 3 label of Assure II (EPA Reg. No. 352-541) indicates that grazing of livestock is prohibited in treated areas. This restriction is not considered practical. Based on the most recent version of the label (dated 04/12/ 20 12), this restriction has not yet been removed.


### DuPont: DuPont would like to discuss the possibility for a modified version of the grazing statement i.e. "Do not graze li vestock in areas treated w ith Assure II for xx days after treatment. " DuPont agrees to modify the second statement to "Do not feed forage , hay, or straw from treated areas to livestock."


### HED: For most crops, livestock grazing and feeding restrictions or prohibitions on labels are not consider ed practical as the treated commodities may not always be under grower control (Table 1 Feedstuffs (June 2008)). For the same reason , a livestock restriction with a pre-grazing or preharvest interval may also be considered impractical. The restriction should be removed from the Assure II label. If desired, a feeding or grazing restriction may be imposed only for soybean forage, silage, or hay (those treated commodities considered being primarily under grower control). Note that the removal of the livestock restrictions from the labels will not have an impact the current estimated livestock dietary burden or on the current to lerance s of qui zalofop on livestock commoditi es (meat, milk, eggs). 

### 2) Multi-residue Methods (MRM) (860.1360): Multi-residue method data (recovery data) for the metabolites, quizalofop acid and quizalofop-methyl remain outstanding.


### DuPont: Further evaluation of the existing multi-method data submitted previously for quizalofop ethyl; PAM, Vol. 1, Appendix II (FDA PESTDATA database dated 10 /99) is required.


### HED: Upon submission, HED will review any additional MRM data to determine if the requirement for MRM recovery data on the metabolites (quizalofop acid and quizalofop-methyl) has been fulfilled. 3) 

### Storage Stability (860.1380): Storage stability data for quizalofop-P-ethyl and quizalofop acid inion field corn and processed commodities have not been received. The available wheat storage stability data were tentatively considered adequate to support submitted crop field trial on corn. However, when the storage stability study on corn is submitted , the adequacy of the storage stability data will be re-evaluated.


### DuPont: Storage stab ility data for field corn were submitted in March 2013 and the report was assigned MRID 49090601.


### HED: A storage stability study has been submitted for quizalofop-P-ethyl and its acid form , quizalofop-P, in corn commodities (MRID 49090601; Dow AgroSciences LLC). That study has been reviewed by HED (I. Negron-Encarnacion, 711 I/ 13, D410951) with the following
Page 2 of 4conclusion: HED tentatively concurred that residues of quizalofop-P-ethyl can be quantitatively monitored in stored samples by measuring residues ofboth quizalofop-P-ethyl and its acid form quizalofop-P. Based on this , HED determined that the tolerances proposed for residues of quizalofop ethyl on field corn are still adequate. However , the storage stability study (MRID 49090601) was tentatively classified as scientifically acceptable pending adequate resolution of the following issues: ( 1) the study did not include a description ofhow samples were prepared prior to frozen storage (e.g., stored whole, coarsely chopped, or homogenized); (2) the limits of quantitation for the method were not reported; (3) no data were provided for apparent residues in unfortified samples; (4) individual results for quizalofop-P in samples fortified with quizalofopP-ethyl were not reported; and (5) no raw data, such as dates of analysis, dilution factors, peak heights/areas, or method correction factors, were included with the study. DuPont recently submitted a revised storage sta bility report (MRID 4919480 1) addressing the above issues. HED has reviewed the revised report and the deficiencies previously noted were addressed (1. NegronEncarnacion; 10/21113; D4 14248). The previous study can be upgraded to scientifically acceptable. 4) Processed Food and Feed (860.1520): Studies to determine the residues inion cotton, meal; cotton, hulls; cotton gin byproducts; and cotton, refined oil are required to determine if separate tolerances are needed for these food/feed items.
DuPont: The current pre-harvest interval restriction for cotton is 80 days and DuPont believes that this supports the need for current tolerance on undelinted seed cotton.
HED: EPA has recently received a data waiver request (no MRID) from DuPont Crop Protection, for the residue studies on cotton gin byproducts. HED has evaluated that waiver request and also reexamined the need for the processing studies on the other cotton processed commodities (cotton, meal; cotton, hulls; and cotton, refined oil). That review may be found in Quizalofop-P-Ethyt. Response to the Waiver Request from DuPont on the Cotton Processing Studies (I. Negron-Encarnacion, 09/25113, D4 12960) with the following conclusions: Potential residues in cotton gin byproducts will not have an effect on the livestock dietary burden, li vestock commodity tolerances, or the dietary risk assessment. HED recommends waiving t he cotton gin byproducts magnitude ofresidue st udies and recommends the establishment of a tolerance of 3 ppm for residues of quizalofop ethyl in cotton gin byproducts based on translation of pea vine residue data. Processing studies for the other cotton commodities (cotton, meal; cotton, hulls; and cotton, refined oil) are not needed and tolerances need not be established for residues of quizalofop ethyl in those cotton processed commodities. 5) Submittal of Analytical Reference Standards (860.1650): A reference standard of 2- methoxy-6-chloroquinozaline should be sent to the analytical standard repository.
DuPont: Will confirm any issues to synthesize this metabolite reference standard and esti mated timeline to ship to the USEPA repo sitory. HED: HED acknowledges DuPont' s intent to prepare and ship the 2-methoxy-6- chloroquinozaline standard to the repository and to inform EPA of the estimated timeline.

Page 3 of 4Standards may be sent to the attention ofeither Theresa Cole or Thuy Nguyen at the following address:
US EPA National Pesticide Standards Repository/Ana l ytical Chemistry Branch/OPP 701 Mapes Road Fort George G. Meade , MD 20755-5350

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