# ~ DowAgroSciences

DowAgroSciences LLC 9330 Zionsville Road Indianapolis, IN 46268 USA Bldg 308/2E January 31, 2014

OPPT DocumentControl Office (DCO) EPAEast Building RoomE6428 (202-564-8930) U.S. Environmental Protection Agency 120 I Constitution Ave., NW Washington. D.C. 20004 Attention: 40CPR 

### 799.5087; Docket lD Number EPA-H(H)PPT-2007-0531 CBIC Control Number 

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Subject: Extension Request for testing ofPhosphorochlorideothioic Acid, 0.0-diethylEster (CAS 2524-04-1 or DEPCT)

ToWhom ItMayConcern:
Dow AgroSciences appreciates the recent granting ofan extensionrequest for the HPV TSCA testing for CAS 2524- 04-1 (DEPCT). Our studyplan is currently due 28 February 2014 with the final reports for the studies due 31 December 2014. Ourlaboratories are notexperienced with analytical and toxicological testing ofthis raw material, which we purchase from other suppliers, and when we initiated preliminary testing recently we quickly learned that this molecule is highly unstable and quickly degrades in most commonly used exposure media, including water and animal feed. Wehad not anticipated the method development experimentation (preliminary testing) that will be required in order to conductthe HPV TSCA testing asrequired byEPA. Therefore, we propose a slight modification to the testing and submission timeline for CAS 2524-04-1 from the dates stated above. We could still submita studyplan describing all ofthe preliminary testing such as hydrolysis study in water, degradation in exposure media, and analytical method developmentby Feb 28,2014. We would then report the results ofthese preliminary studies by August29, 2014 and include stability and tox data obtained from other sources. Dow would then submit a second studyplan with protocols specific for the testing described in the Federal Register notice for HPV molecules (Vol76, No 5, 7 January 2011, pg 1067), with testing modified based on the preliminary stability and degradation testing. This second studyplan would be submitted by September30, 2014. We would then complete all subsequentphysical chem, tox and fate studies, and submitreports by

### June 30, 2015. In order to stay on such a timeline, we will need relatively quick (4-6 weeks) study plan reviews from EPA after the submissions ofstudy plans, because we don't want to initiate studies until the study plans have been approved byEPA.

®TMTrademark ofThe Dow Chemical Company ("Dow") or an affiliated company ofDow' Attention: 40 CFR 

### 799.5087; Docket lD Number EPA-H(H)PPT-2007-0531 Subject: Extension Request for testing ofPhosphoroch1orideothioic Acid, 0.0-diethylEster (CAS 2524-04-1 or DEPCT January 31, 2014 Page2

Dow AgroSciences is committed to complying with the HPV TSCA testing requirements, but need the flexibility accomplished with more time to conduct the preliminary testing required to conduct quality studies. As described in prior communications regarding CAS 2524-04-1, the riskto human health and the environment is minimal for this raw material used in the production ofchlorpyrifos, so hopefully this shortextension can be accommodated in order to conduct the required studies in a thorough and high quality manner. Ifyou have questions, please contact me at 317-337-3774 or dwlickfeldt@dow.corn. Respectfully,

Darin Lickfeldt, Ph.D. US Regulatory Manager Regulatory Science & Government Affairs Dow AgroSciences LLC 9330 Zionsville Rd. Indianapolis. IN46268 Office: 317-337-3774 Fax: 317-337-4649 dwlickfeldt@dow.com