UMlTED S"$ATES ENVIRQNMENTAL PROTECTtON AGENCY 

WASHINGTON D.C., 20458 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

DATE: August 25,2010 

DP Barcode: 380906 

PC Code: 1 14402 

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 1 14402). Specifically, this memorandum addresses a comment from the 

Physicians Committee for Responsible Medicine (PCRM) dated June 1,20 10. 

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 adoption by 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-slope test, and (3) LD50 only test. The test 

method selected will depend on whether or not a definitive median dose (LD50) and sl~pe of the 

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." 

TEXT SEARCHABLE DOCUMENT - 2010
EFED Response: 

The Agency requires a toxicity test be conducted to estimate the acute oral LD50 of sodium 

acifluorfen to a passerine species. PCRM recommends that the new OECD test guideline be 

used for this test because it uses considerably fewer animals than the traditional LD50 test 

described by Test Guideline 850.2 100. The new OECD test guideline for measuring avian acute 

oral toxicity with a sequential dosing procedure is Test Guideline (TG) 223. Current policy 

within the Office of Pesticide Programs/Environmental Fate and Effects Division (EFED) 

regarding the acceptance of avian acute effects studies conducted using the TG 223 protocol 

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 of the 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 of the OECD validation report to determine if the 

TG 223 effects endpoints and doselresponse information adequately address the purposes of the 

avian acute oral data requirement as described in 40 CFR Part 158. Until the Agency's 

evaluation of that 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 data requirements. 

Validation work conducted on TG 223 test guideline to date has 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 doubtful that we would accept studies done urider this 

guideline for fulfilling requirements for passerine acute toxicity data unless additional validation 

work with passerines is done.