UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                       WASHINGTON, D.C. 20460
                                    AUG I 2 1994
                                                    SOLID WASTE AND S.V.Sf1;-:..-'
                                                         RESPONSE

                                    OSWER Directive No. 9285.7-17
MEMORANDUM
Subject:  Role  of  the Ecological Risk Assessment in the Baseline
          Risk  Assessment -,

From:     Elliott  P.  Laws
          Assistant Admini/i
                        •  \
To:       Directors,  Wast^ Management;'Divisions
          Directors,  Environmental Services Divisions
Purpose

     I want to  emphasize the importance of selecting remedies  at
Superfund sites that  are protective of the environment as well as
human health. -  I also want to make it clear that an ecological
risk assessment (ERA)  will be conducted during the Remedial
Investigation  (RI)  at all Superfund sites.

Background

     The Regions are  to be commended for their efforts to deal
with risks to ecosystems, especially with the limited Agency
guidance that has been available.  However, ecological risks at
many sites have only  been addressed superficially, or not until
the site is in  remedial design.

     The National Contingency Plan (NCP) requires that a baseline
risk assessment be conducted by the lead agency during the RI/FS
in order to "characterize the current'and potential threats  to
human health and the  environment"(§300.430 (d)(4)). Administrator
Browner stressed the  importance of balancing human health and
ecological assessments in a memorandum (December 30, 1993) to
Assistant and Regional Administrators that included the following
statement:

     Although not traditionally considered a "component" of an
     ecosystem,  humans are integrally linked to the processes
     that  operate  within their  environment.    Human health
     cannot be divorced from the  "health" of the environment.
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     The condition  of  the ecosystem, therefore,  can  either
     enhance or degrade the well-being of the humans occupying
     the ecosystem.   By integrating ecosystem protection; into
     current programs (including those that  are  directed to
     protect human  health)  we will realize  benefits  to the
     entire ecosystem,  including the human component through
     a more integrated approach.

     In light of this statement, it is essential that we address
both ecological risk assessments and human health assessments
with comparable professional diligence.

Definition and Purpose of the ERA

     An ecological risk assessment estimates the likelihood that
adverse ecological effects (e.g., mortality,  reproductive
failure) will occur as a result of a release of a hazardous
substance at a Superfund site.  The purpose for conducting the
ERA is to:  1) identify and characterize the current and potential
threats to the environment from a hazardous substance release, 2)
evaluate the ecological impacts of alternative' remediation  -•.
strategies, and 3) establish clean-up levels in the selected
remedy that will protect those natural resources at risk.

Scope of the ERA

     While an ERA will be conducted at all Superfund sites, the  .
scope of the assessment will depend upon a number of site-
specific factors;   The physical characteristics of the site, the
toxicity and fate of the contaminants, the proximity to
ecological receptors arid likelihood of exposure, and the
ecosystem types potentially at .risk should all be considered when
planning the ERA.

Next Steps

     Steps are being taken at' Headquarters that will
significantly enhance the Region's risk .assessment capability and
provide programmatic consistency.  A guidance document  for
conducting ecological risk assessments (consistent with the
process described by the Risk Assessment Forum in the Framework
for Ecological Risk Assessment  (EPA/630/R-92/001)) and  a list of
screening level, eco-thresholds are being developed by  the Office
of Emergency and Remedial Response.       .

     If you have any questions about this memorandum, please
contact Stephen Ells, Section Chief, Toxics  Integration Branch,
Office of Emergency and Remedial Response, at  (703) 603-8822.


cc:  Superfund Branch Chiefs, Regions 1-10
     BTAG Coordinators,  Regions 1-10

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