Page 1 of 3

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

VIA E-Mail OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

December 6, 2011

Bruce K. Bernard, Ph.D.

Tetrachlorvinphos Task Force

SRA International, Inc.

5235 Ragged Point Road

Cambridge, MD 21613-3518

Subject: EPA Review and Response to Second Time Extension Request for submission of 

required data from the Tetrachlorvinphos Registration Review Generic Data Call-In (RR083702-28236)

Dear Dr. Bernard:

The Environmental Protection Agency (EPA or Agency) received the Tetrachlorvinphos 

Task Force’s (TCVP TF) 90-day response to the TCVP registration review generic data call-in 

(GDCI-RR-083702-28236) on April 15, 2010. In its 90-day response the TCVP TF indicated 

that data would be generated to satisfy both the immunotoxicity (GLN 870.7800) and UV 

absorption (GLN 870.7050) GDCI data requirements and that an agreement to share the cost to 

develop these data existed between one or more registrants. 

Also in the 90-day response, the TCVP TF requested data waivers for the following seven

studies: hydrolysis (GLN 835.2120), vascular aquatic plant (GLN 850.4400), daphnid chronic 

toxicity (GLN 850.1300), fish early-life stage toxicity (GLN 850.1400), seedling emergence 

(GLN 850.4100), vegetative vigor (GLN 850.4150), and algal toxicity (GLN 850.5400). The 

Agency denied the waiver requests for these data in a letter to the TCVP TF dated September 8, 

2010. 

Subsequent to the Agency’s data waiver request denials (September 8, 2010), the Agency 

received time extension requests on December 21, 2010 (the TCVP TF submitted seven separate 

time extension requests) and February 14, 2011 (the TCVP TF submitted a single time extension 
Page 2 of 3

request for nine data requirements, inclusive of those requested on December 21, 2010), which 

the Agency granted until November 2, 2011. 

On October 20, 2011, the Agency received a second registration review GDCI time 

extension request for thirteen studies listed below (in Table 1). The TCVP TF indicated that it 

was not in a position to financially commit and authorize laboratories to start the generic DCI 

studies until the TCVP tolerances had been reinstated on September 16, 2011. As a result the 

Task Force requested additional time to submit the required data and proposed several due dates. 

The Agency has completed its review of the TCVP TF’s (10/20/2011) time-extension 

request for thirteen studies and has concluded that the TCVP TF’s rationale and proposed 

timeframes for conducting these data are adequate justification for a time extension. Therefore, 

the Agency will grant a time extension for submission of these thirteen data requirements. 

However, due to multiple waiver and time extension requests, with the latter being 

submitted just prior to a previously extended due date, the Agency is requiring that the TCVP TF 

submit interim progress reports. Therefore, the TCVP TF is required to submit to the Agency a 

progress report which includes the name of the laboratory conducting the study, current status of

the study, justification for any further delays and anticipated submission date of the final report

for each data requirement as a contingency of the Agency’s approval of this time extension.

During its review of the TCVP TF time extension request, the Agency also identified two 

errors, where-in the TCVP TF indicated that the terrestrial field dissipation and aquatic field 

dissipation independent laboratory validation (ILV) methods were due by December 29, 2012. 

These data are in fact due to be submitted to the Agency by December 29, 2011. However, based 

on the rationale and timeframes provided in the TCVP TF’s time extension request, the Agency 

has determined that an extension of the due dates for these data would be acceptable. As a result, 

the Agency is extending the due date for the ILV methods from December 29, 2011 to May 30, 

2012 and is requesting that the TCVP TF submit a current progress report for these data by 

February 29, 2012 (Table 1).

In regards to the thirteen data requirements which the TCVP TF submitted a time-extension 

request, the Agency has grouped these requirements as indicated below. The first subset of nine 

data requirements are due by March 30, 2012 and require the submission of recent progress 

report by January 31, 2012. The remaining four data requirements (also provided below in Table 

1) are due by September 15, 2012 and require the submission of a current progress report by 

April 15, 2012. 

Table 1. Progress Report Schedule and Extended TCVP Reg. Review DCI Due Dates

Progress Report Due January 31, 2012 & 

Due Date Extended to March 30, 2012

850.1300 - Aquatic invertebrate life cycle (freshwater)

850.1400 - Fish early-life stage (freshwater)

850.4100 - Terrestrial plant toxicity, Seedling emergence (Tier II)

850.4150 - Terrestrial plant toxicity, vegetative vigor (Tier II)

850.4400 - Aquatic plant growth (aquatic vascular plant toxicity, Tier II)