Jill Bloom/DC/USEPA/US 

09/28/2006 04:01 PM

	To

	IanC@amvac-chemical.com

	cc

	Margaret Rice/DC/USEPA/US@EPA, Tom Myers/DC/USEPA/US@EPA

	bcc

	

	Subject

	PCNB; request for extension of comment period

	

	

Dear Ian,

 Debbie Edwards has asked that I respond to your letter of September 22,


which provides the reasoning behind your request for a 60-day extension
of 

the comment period on the PCNB RED.

 You indicate that the food web model is not available through the link 

provided in the RED (http://www.epa.gov/glnpo/lmmb/foodweb.html).  We
note 

that the website associated with that link provides a narrative 

explanation for the model, but does not provide the model itself.  The 

model is in the form of an Excel spreadsheet and I have attached two of 

the model runs in the form of spreadsheets (representing a range of
values 

for the partition coefficients) to this email.  You will see that the 

spreadsheets show input values, calculations, and results summaries.  

Please let me know if you need any additional information to facilitate 

your analysis of the model or results. We regret this oversight, and I
am 

certain we could have provided these materials quite promptly had you 

informed us of your need for this information when the RED and
associated 

supporting documents became available in early August.

 Your letter states that the RED uses a different study to identify the 

chronic endpoint for mammalian wildlife than that used by the Agency 

previously.  The RED does make reference to a more sensitive endpoint in


discussing the ways the Risk Quotient method might underestimate the 

ecological risks associated with PCNB use (focusing mainly on fate 

characteristics), but the endpoint used to calculate chronic mammalian 

risk quotients in the RED is the same as it has been from the earliest 

versions of the EFED assessment.  The risk quotients then and now are 

based on a rat NOEC of 200 ppm (from MRID# 434693-03).  In any case, I
am 

providing the citation for the more sensitive endpoint.  The Agency’s
risk 

quotients and conclusions about risk to mammalian wildlife associated
with 

the use of PCNB remain the same regardless of this reference:

MRID# 419187-01; Schardein, J. (1991) PCNB: Two-Generation Reproduction 

Study in Rats: Lab Project Number 399-086.  Unpublished study prepared
by 

International Research and Development Corporation. 633 pages.

 Our records indicate that this study was submitted by Uniroyal,
Chemtura’

s predecessor.  We are not legally able to provide the study to Amvac,
but 

I have asked Chemtura to provide a copy to you. 

 A footnote to your letter lists a number of documents submitted by
Amvac 

in the last year which have not been placed on the PCNB docket, and you 

write that you believe they may have not been considered by the Agency. 


You indicate that additional time is needed for Amvac to determine
whether 

these submissions were considered and how the Agency responded.  As all 

the cited documents originated with Amvac, and have been considered by
the 

Agency in development of the RED, we do not believe this review warrants


additional time.  We will docket the items in question.

 We do not agree that an extra 60 days is needed to address your
concerns 

as expressed in the September 22 letter.  We are extending the comment 

period for 30 days to allow for your further review.  A Federal Register


Notice extending the comment period is expected to publish tomorrow.

     Sincerely,

     Jill Bloom

Attached:  Excel spreadsheets

(Note to the files:  these attachments are docketed as
OPP-2004-0202-0106 and OPP-2004-0202-0107)

Jill Bloom, Review Manager

US Environmental Protection Agency

Office of Pesticide Programs

Special Review and Reregistration Division

703-308-8019

fax: 703-308-8041

