UMlTED S"$ATESENVIRQNMENTAL PROTECTtON AGENCY WASHINGTON D.C., 20458

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

MEMORANDUM DATE: August 25,2010 DP Barcode: 380906 PC Code: 114402

SUBJECT: EFED Response to Comments on Preliminary Work Plan for Sodium Acifluorfen

FROM: Dana Spatz, Chief Environmental Risk Branch I1 Environmental Fate and Effect Division Office of Pesticide Programs

TO: Christina Scheltema, CRM Michael Goodis, Chief Risk Management and Implementation Branch 3 Pesticide Re-evaluation Division (7508P)

This memo communicates the response of the Environmental Fate and Effects Division (EFED) to comments received on the Preliminary Work Plan for the Registration Review of Sodium Acifluorfen (PC Code 114402). Specifically,this memorandum addresses a comment from the Physicians Committee for Responsible Medicine (PCRM) dated June 1,2010.

PCRM Comment:

"The Summary Document indicates that the Agency may request testing for avian acute oral toxicity. We strongly support the use of the newly revised OECD test guideline for the acute avian oral toxicity, which is on the verge of official adoptionby the OECD. The new approach could reduce the total number of animals by up to approximately 90%. The approach provides three testing options: (1) limit dose test, (2) LD5O-slopetest, and (3) LD50 only test. The test method selected will depend on whether or not a definitive median dose (LD50) and sl~pe ofthe dose-response curve are both needed.



### ...We hope the Agency will use the OECD's draft test guideline to minimize the number of animals used while still accounting for the safety of wild birds."EFED Response:

The Agency requires a toxicity test be conducted to estimate the acute oral LD50of sodium acifluorfento a passerine species. PCRM recommends that the new OECD test guidelinebe used for this test because it uses considerably fewer animals than the traditional 

### LD50 test described by Test Guideline 850.2100. The new OECD test guideline for measuring avian acute oral toxicity with 

### a sequential dosingprocedure is Test Guideline (TG) 223. Current policy within the Office of Pesticide Programs/EnvironmentalFate and Effects Division (EFED) regarding the acceptance of avian acute effects studies conducted using the TG 223protocol states the following:

Until the OECD TG 223 validation process is completed and the guideline has been approved by OECD, studies that utilize this guideline should not be classfied;pending results ofthe validation, they may then be classijied as 'acceptable, 'assuming that they meet all other guideline requirements.

To date the OECD has adopted the TG 223 guideline and has issued a validation report. At this time EFED is actively evaluating the results ofthe OECD validation report to determine ifthe TG 223 effects endpoints and doselresponse information adequately address the purposes ofthe avian acute oral data requirement as described in 40 CFR Part 158. Until the Agency's evaluation ofthat validation report is completed, EFED will not classify avian toxicity studies performed using the TG223 protocol and the studies cannot be used to fulfill data requirements. Therefore,we cannot say at this time whether or not avian toxicity studies done under TG 223 will be acceptable to meet our datarequirements.

Validation work conducted on TG 223 test guidelineto datehas been limited to studies with the upland game birds (e.g., northern bobwhite). Because no work has been done to date to validate this guideline for passerine species, it is doubtfulthat we would accept studies done urider this guideline for fulfillingrequirements for passerine acute toxicity data unless additional validation work with passerines is done.