Letter regarding additional comments on Pathway Exposure Report Draft
August 26, 1994 \7 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? …
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August 26, 1994 \7 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 007 1127 *64960* 64960 de maximis Additional Comments On Pathway Exposure Report Draft August 26, 1994- 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 OO7 1123 'PAPER