EPA Meeting with Tetrachlorvinphos Registrants to discuss the Registration Review 

Generic Data Requirement Waiver Responses

November 02, 2010

Participants

James Parker/PRD

Laura Parsons/PRD

Neil Anderson/PRD

Michael Metzger/HED

Paul Chin/HED

Christine Olinger/HED

Greg Orrick/EFED

Bruce Bernard/Hartz and KMG Representative

John Riner/KMG Consultant

Roger Jackson/KMG-Bernuth

Robert Rosenwasser/Hartz Mountain

On November 02, 2010, the EPA met with the tetrachlorvinphos (TCVP) registrants (and 

consultants) also known as the Tetrachlorvinphos Task Force (TCVP TF) at their request to 

discuss the Agency’s responses to data waivers submitted to the Agency as a part of their 90 day 

response to the generic data call-in (GDCI). During this meeting, the Agency clarified that the 

TCVP samples used in earlier studies (under PC Code 083701) have been identified as 

equivalent to samples which have been used in more recent studies (under PC Code 083702). 

Therefore, the TCVP technical grade active ingredient (TGAI) used in all studies submitted to 

the Agency consisted of the Z-isomer, regardless of chemical name and CAS numbers used. 

Also, the TCVP TF agreed to submit two inhalation protocols to the Agency for review which 

will be used to support the registration review human health risk assessment by providing 

additional inhalation exposure data (per Organophosphates my cause respiratory lesions). 

During the meeting, the TCVP TF also indicated that TCVP would not result in exposures of 

more than 14-days. As a result, the TCVP TF indicated that they preferred not to submit the 28 

day guideline study, but instead would submit two protocols for alternate inhalations studies 

(along with supporting data). The two protocols which the TCVP TF indicated that they would 

submit to the Agency included a 14 day inhalation protocol (with a 14 day continuation, in case 

effects are identified) and a 28 day inhalation protocol, both of which will be based on a 

validated gravimetric method. Once these protocols are submitted, the Agency will determine 

whether or not either of these study protocols will be acceptable by the Agency. 

This meeting also covered the TCVP GDCI data requirements for a manure dissipation study and 

environmental chemistry methods in soil and water. In regards to the Manure dissipation study, 

the Agency indicated that the previous Manure dissipation study did not follow the protocol 

approved by the Agency and excluded the TCVP parent compound. The TCVP TF agreed to 

submit a protocol (which would include data to indicate the number of animals used) for a nonradiolabeled (cold) Manure Dissipation study, which will be reviewed by the Agency. The 

typical end-use product should be used as directed for this study (manure should not be treated 

with TCVP after passing from the livestock). Residues in manure should be analyzed for TCVP 
and the transformation products of concern to determine the decline of parent compound and the 

formation and decline of transformation products once passed from livestock. If different from 

submitted analytical methods in soil, the analytical method used in the study will need to be 

validated and independently validated following OCSPP guideline 850.6100 (formerly 850.7100; 

40 CFR Part 158.1300, which requires independent validation of field studies other than 

combination and tank mix studies). 

Also, guideline-compliant (OCSPP guideline 850.6100) independent laboratory validation (ILV) 

reports are required to support the submitted analytical methods in water and in soil, in addition 

to a guideline-compliant report for the analytical method in soil (as discussed in the Agency’s 

July 20, 2010 EFED Response to Comments and Waiver Requests document (DP346876)).

The registrants indicated that data were submitted indicating that dimethyl hydrogen phosphate is 

the main phosphate-containing degradate. The Agency indicated that the dimethyl phosphatecontaining degradate are not of concern for human health. However, the Agency would 

determine whether there are ecological concerns for the dimethyl phosphate-containing 

degradates, which should be included as analytes in the manure dissipation study (the degradates 

that are of concern to the Agency were forwarded to the registrants via email on November 16, 

2010).

In conclusion, this meeting also covered data requirements for several outdoor ecological data 

requirements, which remain as data gaps (as discussed in the 7/20/10 response to waiver request) 

for which the TCVP TF indicated that they intend to submit the appropriate data to satisfy these 

ecological data requirements.