August 26, 1994
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de maximis, inc.
186 Center Street
Suite 290
Clinton, NJ 08809
(908) 735-9315
Fax (908) 735-2132
Carolyn Kwan
United States Environmental Protection Agency
Region II
26 Federal Plaza, Room 737
New York, NY 10278
VIA FAX AND US MAIL
RE: 
Additional Comments On Pathway Exposure Report Draft
Dear Carolyn:
My apologies for not getting all comments on this subject into one letter to you. TEIC
representatives have reviewed this document and offer the following comments:
Section 2 
It is unclear what is meant by the "range of non-detectable
concentrations." 
The authors need to explain more fully what the
toxicity-concentration 
screen is, how it is applied to arrive at
constituents of concern, and what the "other criteria" are.
Section 3 
Exposure Point Concentration: Section 3 on this subject is brief. It will
ultimately be important to understand what data will be combined for
purposes of deriving the mean and 95% UCL.
Particles Inhalation Pathway; Inhalation of particles during construction
seems rather conservative. How is particle respirability addressed?
Exposure Parameters (Table 9): The sources for all these assumptions
need tc be referenced. Scrne of the "default" assumptions may not be
reasonable for this site, eg., 100 mg/day resident adult soil ingestion
seems high. Also, Fl should be site specific and not 1.
The 1992 EPA Dermal Exposure Assessment Principles and Applications
should be used, since its soil exposure frequency values are more
realistic. 
The 1992 EPA Exposure Assessment Guidelines provide
guidance on quantitative uncertainty analysis and should be used.
Table 9 should include exposure parameters and sources for central
tendency exposure.
What is CA/SSC, and how is it assigned to be 0.07 mg/cu.m.? What are
PC and VF?
TUT 
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de maximis
Additional Comments On Pathway Exposure Report Draft
August 26, 1994-
Page 2
Section 4: 
What use is being proposed for subchronic RfDs?
The most recent HEAST FY-1994 should be used instead of FY-1993.
Page 27, first paragraph, caveat on the Linearized Multistage Model for
cancer should be added, "Such an estimate, however, does not
necessarily give a realistic prediction of the risk. The true value of the
risk is unknown, and may be as low as zero."
Page 27, last paragraph, dioxin TEFs should also be used.
Section 5: 
Last paragraph, what are the sources for ARARs?
Section 7: 
The PRGs document is not usually a part of baseline risk assessment.
Why is it here?
Ecological Risk Assessment:
An ecological assessment is being proposed. Is there a need for this?
No other comments on this document will be offered. Please call me if you have any
questions.
Very truly yours,
de maximis, inc.
John P. McBurney
cc: 
Paul Ryan
Tutu PRP Technical Committee
RLE: 3089.03\ADJLCOM
TUT 
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'PAPER