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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

MEMORANDUM

Date: February 23, 2012

SUBJECT: Quizalofop-P-ethyl: Amendment to the Human Health Risk Assessment and 

Summary of Analytical Chemistry and Residue Data for New Uses on Sorghum, Rapeseed Crop 

Group 20 A, and Field Corn

PC Code: 128709 DP Barcode: D398731

Decision No.: 441518 and 443799 Registration No.: 352-541 and 352-542

Petition No.: 0E7802 and 1F7822 Regulatory Action: Tolerance Petition

Risk Assessment Type: NA Case No.: NA

TXR No.: NA CAS No.: 100646-51-3

MRID No.: NA 40 CFR: § 180.441

FROM: Ideliz Negrón-Encarnación, Ph.D., Risk Assessor

Risk Assessment Branch V

Health Effects Division (7509P)

Office of Pesticide Programs

THROUGH: William Donovan, Ph.D., Chemist

Michael Metzger, Branch Chief

Risk Assessment Branch V

Health Effects Division (7509P)

Office of Pesticide Programs

TO: Laura Nollen, Risk Manager

Risk Management Division (RM 5; 7508 P)

and

Mindy Ondish, Risk Manager 

Risk Management Division (RM 25; 7508P)
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An amendment to the Human Health Risk Assessment (D384660 and D386678) and the 

Summary of Analytical and Residue Data (D395630) for new uses of quizalofop-P-ethyl was 

required to address changes in the commodity definition of feedstuff commodities, grazing 

restrictions and adjuvant specifications. In addition, clarification on the decision for the storage 

stability studies of field corn was needed. The registrant is undergoing a storage stability study

with field corn which will be further evaluated; however, storage stability was proven for wheat 

which is tentatively used to cover that of the field corn samples. Based on this, HED 

understands that a conditional registration is not necessary for this case.

1. Tolerances for meal commodities

RAB V recommended the creation of the rapeseed, subgroup 20A, meal, except flax, meal to 

propose tolerances for the meal commodities under the rapeseed, subgroup 20A, seed, except 

flaxseed. OPP further evaluated the proposal and considered that the registrant proposal was 

adequate for this case. In addition, the preferred commodity term for canola is rapeseed. 

Therefore, recommended commodity definitions and tolerances for the meal commodities 

are: 

gold of pleasure, meal 2.0 ppm

crambe, meal 2.0 ppm

rapeseed, meal 2.0 ppm

2. Grazing restrictions

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 and should be 

removed. However, the grazing interval established in the supplemental labels for use in 

field corn containing DAS-40278-9 and sorghum containing the INZEN AII herbicide 

tolerant trait are considered appropriate because they match the PHIs established in the label. 

Therefore, the following directions should be kept in the supplemental labels. 

 Field corn containing DAS-40278-9: “Do not allow grazing on treated corn within 30 

days of application.”

 Sorghum containing the INZEN AII herbicide tolerant trait: “Do not graze livestock 

in treated areas or feed treated grain, forage, fodder, straw, or hay to livestock within 

45 days of Assure II application.”

3. Adjuvant specifications

It was noted that the use of adjuvants established in the supplemental label for sorghum need 

to be modified to reflect the conditions of the field trials. The adjuvant concentration was

1% (v/v) of the COC in all trials except one in which they used 0.25 % (v/v) of the NIS. The 

residue data only supports 1% of the COC or 0.25% of the NIS. Therefore, the label should 

be modified accordingly since in the draft label up to 2% COC and 0.5% NIS is 

recommended.