September 23, 1997
EPA-SAB-EC-COM-97-002
Ms. Carol M. Browner
Administrator
US Environmental Protection Agency
401 M St. SW
Washington, DC 20460
Subject: Commentary on the Question of Agency Benchmark Values for
Ecological Toxicity
Dear Ms. Browner:
SUMMARY
This Commentary from the SAB Executive Committee is meant to alert the
Agency to the question of the need for and advisability of an institutional mechanism
that will lead to Agencywide consensus values to characterize ecological toxicity of
pollutants.
BACKGROUND
At its July 23, 1997 meeting the SAB Executive Committee (EC) reviewed a draft
report from its Ecological Processes and Effects Committee (EPEC) dealing with
OSWER guidance on "ecotoxicity threshold" values. The intent of the ecotoxicity
threshold values is to provide guidance to workers in the field on whether the levels of
pollutants at contaminated sites merit more rigorous risk assessments or not, based on
ecotoxicity concerns. Operationally, this would mean that if the level of contamination
is below some level (the "threshold"), then a more sophisticated ecological risk
assessment is not called for. If, on the other hand, the level of contamination is above
the threshold, then more rigorous ecological risk assessment would be undertaken.
You have recently received the Board's advice ("Evaluation of Superfund Ecotox
Threshold Benchmark Values for Water and Sediment", EPA-SAB-EPEC-LTR-97-009,
August 8, 1997) on the focused question of ecotoxicity threshold.
However, larger concerns surfaced during the course of the discussion by the
EC that the SAB intends to investigate further. For example, the fact that there are a
number of different approaches taken by different groups inside and outside the
Agency to derive these ecotoxicity threshold values raises the possibility of users
"shopping around" for a value that suits their particular needs. Also, the wide range of
organisms that exist in the various types of ecosystems across the country raises new
questions about the adequacy of research and test methods upon which ecotoxicity
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threshold values might be based. Such questions generally do not arise when
examining comparable toxicity issues associated with human health. In the latter
instance, the Agency developed the Integrated Risk Information System (IRIS) more
than a decade ago to address the "shopping around" issue associated with human
toxicity values; cf., q1*s and RfDs.
We recognize the value of having such consensus numbers on ecotoxicity
available when devising and selecting risk reduction options.
Because it is such an important, Agency wide issue we plan to mobilize a cross-
SAB group to explore the scientific problem and technical prospects in embarking upon
development of such a system. Our intention is to have a Consultation with appropriate
parties from across the Agency to learn about ecotoxicity values and to share insights
with professionals within the Agency. From these discussions, we will generate some
ideas about an appropriate course of action for the Board and the Agency in order to
address these issues.
We look forward to your reaction to this commentary and to any suggestions that
the Agency might have as the SAB develops its plans in this area.
Sincerely,
Dr. Genevieve Matanoski, MD, MPH
Chair, Executive Committee
Science Advisory Board
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U.S. ENVIRONMENTAL PROTECTION AGENCY
SCIENCE ADVISORY BOARD
EXECUTIVE COMMITTEE
1997
CHAIR
Dr. Genevieve M. Matanoski, Professor of Epidemiology, School of Hygiene and Public
Health, The Johns Hopkins University, Baltimore, MD
MEMBERS
Dr. Richard J. Bull, Senior Staff Scientist, Battelle Pacific Northwest National
Laboratory, Molecular Biosciences, Richland, WA
Dr. Maureen L. Cropper, Principal Economist, PRDEI, The World Bank, Washington,
DC
Dr. Joan M. Daisey, Program Head, Indoor Environment Program, Lawrence Berkeley
National Laboratory, Berkeley, CA
Dr. William H. Glaze, Professor, Department of Environmental Science and
Engineering, Interim Director, Carolina Environmental Program, University of
North Carolina, Chapel Hill, NC
Dr. Mark A. Harwell, Director, Center for Marine & Environmental Analyses, RSMAS,
University of Miami, Miami, Fl
Dr. Morton Lippmann, Professor, Nelson Institute of Environmental Medicine, New York
University Medical Center, Tuxedo, NY
Dr. Alan W. Maki, Environmental Advisor, EXXON Company, USA, Houston, TX
Dr. Joe L. Mauderly, Director of External Affairs, Lovelace Respiratory Research
Institute, Albuquerque, NM
Dr. Granger M. Morgan, Head, Department of Engineering & Public Policy, Carnegie
Mellon University, Pittsburgh, PA
Dr. Ishwar P. Murarka, Technical Executive, Electric Power Research Institute, Palo
Alto, CA
Dr. EmilA. Pfitzer, President, Research Institute for Fragrance Materials, Inc.,
Hackensack, NJ
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Dr. Paul R. Portney, President and Senior Fellow, Resources for the Future,
Washington, D.C.
Dr. William Randall Seeker, Senior Vice President, Energy and Environmental
Research Corp., Irvine, CA
Dr. Ellen K. Silbergeld, Professor of Epidemiology and Preventive Medicine,
Department of Epidemiology, University of Maryland, Baltimore, MD
Dr. James E. Watson, Jr., Professor, Department of Environmental Sciences and
Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC
LIAISON FOR SCIENTIFIC ADVISORY PANEL
Dr. Ernest E. McConnell, President, ToxPath, Inc., Raleigh, NC
LIAISON FOR ORD BOARD OF SCIENTIFIC COUNSELORS
Dr. Costel D. Denson, Vice Provost for Research, University of Delaware, Newark, DE
SCIENCE ADVISORY BOARD STAFF
Dr. Donald G. Barnes, Designated Federal Official, US EPA, Science Advisory Board
(1400), 401 M Street, SW, Washington, DC
Mrs. Priscilla Y. Tillery-Gadson, Staff Secretary, US EPA, Science Advisory Board
(1400), 401 M Street, SW, Washington, DC
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NOTICE
This report has been written as a part of the activities of the Science Advisory
Board, a public advisory group providing extramural scientific information and advice to
the Administrator and other officials of the Environmental Protection Agency. The
Board is structured to provide balanced expert assessment of scientific matters related
to problems faced by the Agency. This report has not been reviewed for approval by
the Agency; and hence, the contents of this report do not necessarily represent the
views and policies of the Environmental Protection Agency or other agencies in the
Federal government. Mention of trade names or commercial products does not
constitute a recommendation for use.
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