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liRELIMINARY SUMMARY OF THE U.S. EPA
COLLOQUIUM ON RISK CHARACTERIZATION
SERIES C: OSWER AND REGIONS
(C-l)
Prepared for:
U.S. Environmental Protection Agency
Science Policy Council
401 M Street SW.
Washington, DC 20460
Contract No. 68-D5-0028
Work Assignment No. 96-3
Prepared by:
Eastern Research Group, Inc.
110 Hart well Avenue
Lexington, MA 02173-3198
December 31, 1996
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NOTICE
Mention of trade names or commercial products does not constitute endorsement or recommendation
for use. Statements are the individual views of each meeting participant; the statements in this preliminary
summary do not represent analyses or positions of the Science Policy Council or the U.S. Environmental
Protection Agency (EPA).
This preliminary summary was prepared by Eastern Research Group, Inc. (ERG), an EPA contractor,
as a general record of discussions held during the Risk Characterization Colloquium, Series C: OSWER and
Regions. As requested by EPA, this preliminary summary captures the main points and highlights of the
meeting. It is not a complete record of all details discussed, nor does it embellish, interpret, or enlarge upon
matters that were incomplete or unclear.
Several individuals from EPA and the Science Advisory Board collaborated to organize this
colloquium, including:
Dorothy Patton
Margaret Stasikowski
Donald Barnes
Peter Preuss
Jack Fpwle
Ed Ohanian
Ed Bender
Kerry Dearfield
Ruth Bleyler
Mary McCarthy-O'Reilly
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CONTENTS
Page
PREFACE v
SECTION ONE—BACKGROUND 1-1
EPA's Risk Characterization Policy 1-1
Implementation of EPA's 1995 Risk Characterization Policy 1-2
Meetings Held to Date 1-6
The June 1996 Series C Colloquium 1-8
SECTION TWO—OPENING PLENARY SESSION 2-1
Introductory Presentations . 2-1
Cumulative Risk in Problem Formulation 2-3
Case Study Overviews 2-5
SECTION THREE—BREAKOUT SESSIONS 3-1
Lavaca Bay 3-1
Midlothian 3-4
Biocrude 3-7
Waquoit Bay Watershed 3-9
SECTION FOUR—CLOSING PLENARY SESSION 4-1
General Comments on Implementation Statements and Case Studies 4-1
Adjournment 4-6
APPENDIX A—AGENDA A-l
APPENDIX B—ATTENDEE REGISTRATION LIST B-l
APPENDIX C—CUMULATIVE RISK IN PROBLEM FORMULATION HANDOUTS . C-l
APPENDIX D—CASE PRESENTERS, CHAIRS, AND FACILITATORS D-l
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APPENDIX E—CASE STUDY HANDOUTS E-l
Lavaca Bay E-l
Midlothian E-35
Biocrude ; E-59
Waquoit Bay Watershed E-117
APPENDIX F—PRELIMINARY IMPLEMENTATION STATEMENTS F-l
Region 6 Implementation Statement F-l
Region 9 Implementation Statement F-33
The Superfund Assessment Process F-45
Office of Solid Waste Implementation Statement F-47
Office of Water Implementation Statement F-71
APPENDIX G—RISK CHARACTERIZATION POLICY
BACKGROUND MATERIALS G-l
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PREFACE
On June 6 and 7,4996, EPA's Science Policy Council held the fourth in a series of
internal colloquia on risk characterization. This preliminary summary presents highlights from
the meeting, focusing on issues raised, but generally and deliberately not resolved, in colloquium
discussions. Like the colloquium, the summary is intended to stimulate discussion and generate
ideas. It is presented as a starting point for a continuing Agency dialogue on risk
characterization, not as a statement of positions or a source of answers.
The colloquium series continues and expands the discussion that began with the
Administrator's March 21,1995 memorandum on risk characterization. That memorandum
established core principles for characterizing risk and inaugurated a two-part program to
implement those principles across EPA. For about a year, a Science Policy Council inter-office
risk characterization Implementation Team* has been working to convert the core principles into
useful guidance for Agency assessors and managers. This is conceived as a "bottom-up" exercise,
drawing on the variety of experience among scientists and managers hi different EPA program
offices, regional offices, and laboratories. The risk characterization policy and implementation
program are consistent with a Science Policy Council goal of stimulating broad EPA participation
in important science policy initiatives.
In August 1995, the Implementation Team completed the first stage of the program by
preparing preliminary office-/region-specific statements of principles and procedures for guiding
risk characterization implementation efforts in their respective offices/regions ("Preliminary
Implementation Statements"). The August statements are preliminary because the drafts for
each office/region will be tested and evaluated by both risk assessors and risk managers. Further,
the drafts for many offices/regions will be revised before we are confident that we have workable
statements that are consistent with both the principles set forth in the Administrator's
memorandum and the needs of different EPA offices and programs. The colloquium series is
desiped to encourage this kind of testing throughout the Agency.
In September 1995, EPA held the first in the series of colloquia on risk characterization
issues. It featured risk characterization "cases" from the Office of Air and Radiation (OAR) and
the Office of Research and Development (ORD). The second colloquium featured cases from
the Office of Water (OW) and two offices within the Office of Prevention, Pesticides and Toxic
Substances (OPPTS)—the Office of Pesticides Programs (OPP) and the Office of Pollution
Prevention and Toxics (OPPT). The third meeting was a colloquium and roundtable hi which
risk assessors and risk managers jointly discussed revised versions of the OW and OPPTS cases,
focusing especially on risk management issues affecting risk characterization.
The fourth meeting, the subject of this summary, was held hi June 1996 and featured cases
from the Office of Solid Waste and Emergency Response (OSWER) and EPA regions. All four
colloquia have focused on generic risk characterization issues, with the particular cases presented
only as vehicles for discussing these issues; interested scientists and managers from many
different offices (not just those producing the case studies) participated in the discussions.
Colloquium comments and recommendations will be used to influence future development of
office-/region-specific risk characterization statements. Any Agency review of the cases
themselves will take place through customary procedures.
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As a review of issues raised in the June 1996 jcolloquium, with more meetings planned to
complete the series, this preliminary summary is a work in process. The Science Policy Council
staff will prepare a short summary for each meeting to mark issues raised and progress made.
Each meeting summary will begin with a background section that briefly explains the history of
risk characterization policies and their implementation within EPA. Except for minor
adjustments to reflect progress made in the implementation program, the same background
section will appear in each meeting summary. The remainder of each meeting summary will
consist of ideas discussed in the meeting.
At the conclusion of the colloquium series, the Science Policy Council will collect relevant
information and materials into a final report At that time, the Council will also work with
Agency program offices and regions to plan and schedule external peer review activities.
Dorothy E. Patton, Ph.D.
Acting Director, Office of Research and Science Integration
Executive Director, Science Policy Council
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SECTION ONE
BACKGROUND
EPA'S RISK CHARACTERIZATION POLICY
NOTE: Background material for the report from each colloquium in the series is essentially
identical so that the different colloquium audiences will have the same information.
The cases and outcomes vary for the different colloquia.
At EPA, analyses of scientific information on risks to human health and the
environment—risk assessments—are among the most important factors decision-makers consider
when making policy decisions. Recognizing the critical role of risk assessments, EPA has long
token steps to ensure that Agency risk assessments are sound and credible. For example, EPA
has developed a variety of human health risk assessment guidelines over the years, many of which
specify methods and procedures for conducting the first three steps in the risk assessment process
(hazard identification, dose-response assessment, exposure assessment).
In the early 1990s, several observations prompted EPA to focus more attention on the
fourth, integrative step (risk characterization) in the risk assessment process. Among these were
observations that EPA risk assessors and risk managers frequently communicated the results of
EPA risk assessments without indicating the range of information considered in developing the
assessments and that they used different descriptors of risk in different risk assessments. In 1992,
EPA issued a policy memorandum and guidance package on risk characterization to encourage
fuller risk characterizations, to promote greater consistency and comparability among EPA risk
characterizations, and to clarify the role of professional judgment in characterizing risk. The
policy called on risk assessors and risk managers to communicate the scientific basis of risk
conclusions (i.e., to provide a combined and integrated view of the evidence with a full and open
discussion of the strengths, limitations, and uncertainties), to use standard descriptors of risk, and
to use multiple risk descriptors—ail with the aim of generating more complete, higher quality,
and more consistent characterizations of risk hi EPA risk assessments.
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Although EPA's 1992 risk characterization policy sparked considerable discussion and
progress, implementation was incomplete. In its 1994 report, Science and Judgment in Risk
Assessment, the National Research Council concluded that "EPA's overall approach to assessing
risks is fundamentally sound despite often-heard criticisms, but the Agency must more clearly
establish the scientific and policy basis for risk estimates and better describe the uncertainties hi
its estimates of risk.* To ensure communication of the scientific basis of risk conclusions and to -
promote greater transparency, clarity, consistency, and reasonableness in risk assessments across
Agency programs, EPA Administrator Carol Browner issued a new risk characterization policy
and guidance on March 21,1995. In this policy, Administrator Browner refines and reaffirms the
principles and guidance found in the 1992 policy and outlines a process for implementing them.
IMPLEMENTATION OF EPA'S 1995 RISK CHARACTERIZATION POLICY
In her March 1995 risk characterization policy statement, Administrator Browner charges
the Science Policy Council (SPC) with organizing Agency-wide implementation activities to
promote consistent interpretation of the policy, to assess the progress of implementation, and to
recommend revisions to the policy and guidance as necessary. In addition, she calls for the
establishment of an Implementation Team (composed of representatives from EPA
Headquarters, program offices, and regions) to coordinate development of office-/regjon-specific
policies and procedures consistent with the policy and guidance.
In April 1995, the SPC established an Implementation Team, which has begun the task of
converting the core principles embodied in Administrator Browner's risk characterization policy
into office-specific guidelines for Agency risk assessors and managers. In June 1995, members of
the Implementation Team prepared first drafts of office-specific implementation statements of
principles and procedures for risk characterization in their offices or regions. In August 1995,
after considerable discussion, they produced preliminary implementation statements for further
discussion and testing.
To ensure the integrity and practicality of the implementation statements, the SPC and
Implementation Team have developed a process for testing, evaluating, and revising the
statements in the context of real-world applications. The process consists of three parallel series
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of meetings at which risk assessors and risk managers will discuss the application of the
implementation statements to specific case studies to determine whether the statements are:
• Specific enough to guide development of good risk characterizations.
• Flexible enough to allow for differences in detail.
• Complete enough to allow objective judgment of compliance.
• Organized in a way that is useful to the office or region.
The three series of meetings will focus on OAR and ORD implementation statements and
case studies, OW and OPPTS implementation statements and case studies, and OSWER and
regional implementation statements and case studies, respectively. As initially envisioned, each
series would include three meetings1 (see figures 1 and 2):
• A colloquium for ride assessors at which office or region personnel will present
case studies and discuss them with attendees to identify, categorize, and suggest
solutions for issues encountered in applying the implementation statements.
After the colloquium, the case study authors will complete risk characterizations
for their case studies.
A coUoquium/roundtable for risk assessors and risk manners at wfa
study authors will discuss how they addressed the issues discussed in the previous
colloquium in their risk characterizations and attendees will discuss issues that
might arise from a risk management perspective. After this meeting, the authors
will re-examine their risk characterizations based on the attendees' comments.
A roundtoble for risk managers and decision-makers at which the case study
authors will present their revised risk characterizations and the attendees will
explore risk management issues in greater detail. After the roundtable, the
authors will complete their risk characterizations for peer review and
Implementation Team members will reconsider and, as appropriate, revise their
office-specific implementation statements.
'Based on substantial progress made during the early meetings, as well as feedback from
meeting participants, the SPC subsequently decided to eliminate the third meeting in each
meeting series. Thus, an "all hands* plenary session will follow the colloquia/roundtables rather
than the roundtables described here.
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Risk Characterization
Colloquia and Roundtables
Series A
Series B
Series C
OAR/ORD
OW/OPPTS
.colloquium
OSVeREGIONS
colloquium
colloquium/
roundtable J~,
colloquium.
colloquium/
roundtabfe
colloquium/
roundtable
(roundtablej
(roundtablej
Croundtablel
PLENARY SESSION
Figure 1. Overall 'structure of EPA1 a planned Implementation meetings,
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General plan for each series
select cases
C colloquium j
"homework"
colloquium/
Toundtable
"homework"
"homework"
Peer Review
Plenary
1. Present case.
2. Identify characterization issues.
3. Receive recommendations.
f. Resolve issues.
2. Prepare risk characterization.
3. Identify expected management issues.
1. Present characterization.
2..Get feedback.
3. Present management issues.
1. Resolve management issues.
2. Modify the risk characterization
to accommodate colloquium
feedback and management issues.
1. Present revised characterization.
focussing on management issues.
2. Get feedback.
1. Complete risk characterization
for peer review.
2. Rework the Offlce/Region-speciflc
Statement
Products
1. Model risk characterization.
2. Revised Office/Region-Specific
Statement.
Figure 2. General plan for each, implementation meeting series.
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These series of meetings will culminate with a plenary session to solicit comments from
internal and/or external reviewers and the public. The SPC and Implementation Team
constructed this meeting plan not only to ensure production of credible, useful office-specific
implementation statements and model risk characterizations, but also to achieve the broader
implementation objectives of.
Tangibly demonstrating EPA's commitment to risk characterization by converting
the risk characterization principles in the 1995 policy into practice in all parts of
EPA.
Providing a multi-office forum for discussion and debate of risk characterization
issues.
Increasing the credibility of Agency risk characterizations.
Developing measurable criteria to help risk assessors and risk managers
understand what is expected of them and to help others measure the success of
EPA risk characterization efforts.
MEETINGS HELD TO DATE
On September 7 and 8,1995, the SPC held the Series A Colloquium on Risk
Characterization ("Meeting Al") in Washington, DC. As the first meeting conducted under the
plan described above, it represented EPA's first opportunity to assert its commitment to risk
characterization and describe the implementation plan to a broad EPA audience of risk assessors
and other interested attendees. To that end, EPA Deputy Administrator Fred Hansen opened
the meeting with introductory remarks on the importance of risk characterization and the
attention being accorded this topic at the highest levels of EPA. Members of the
Implementation Team then provided background information and explained the team's
implementation plans. The remainder of the colloquium focused on the preliminary OAR and
ORD implementation statements, which attendees discussed in the context of four case studies
developed and presented by individuals from these offices. The implementation statements and
case studies sparked lively conversations about risk characterization issues as well as suggestions
for improving future colloquia.
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The Series B Colloquium on Risk Characterization ("Meeting Bl") held on December 14
and 15,1995, in Washington, DC, was the second meeting conducted under the risk
characterization meeting plan. Consistent with its commitment to listen to and adopt useful
ideas from all parts and all levels of the Agency, meeting organizers arranged for many of the
suggestions from the first colloquium to be implemented in this colloquium. For example, they:
• Worked with program offices to reformat the preliminary implementation
statements under discussion at the meeting.
• Met with breakout session chairs, presenters, and facilitators to plan the
colloquium and resolve any remaining issues,
• Worked with case study presenters to develop a consistent format for the case
study handouts (i.e., one that begins with a section on risk characterization issues
followed by a summary of the case).
• Met with the colloquium chair to design an "effective" closing plenary session.
• Asked case study presenters to give fictional names to the compounds addressed
in their cases to encourage free discussion of risk characterization issues.
• Distributed the preliminary implementation statements and case study handouts
prior to the colloquium.
• Assigned facilitators to breakout sessions to "stimulate" discussions.
• Asked the case study presenters to give a brief overview of their cases during the
colloquium's opening plenary session to familiarize the attendees with the case
studies/issues.
• Distributed a suggested format for reports from breakout sessions to ensure
consistency.
During the colloquium, many attendees noted that their suggestions had been
implemented and commented that the changes had enhanced the running and effectiveness of
the colloquium. Indeed, the meeting provided an excellent opportunity to explore in depth the
practical issues involved in using the preliminary implementation statements prepared by OW
and two OPFTS offices (OPP and OPPT).
The Series B Risk Characterization Colloquium and Roundtable ("Meeting B2") held on
May 30 and 31,1996, in Bethesda, MD, was the third meeting conducted under the overall risk
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characterization meeting plan—and the second meeting conducted under Series B. As such, it
featured a colloquium to allow risk assessors and risk managers to jointly discuss risk
characterization issues important to them in the context of case studies (revised versions of those
presented in Meeting Bl) and a roundtable to provide a forum for open discussion of risk
management issues with risk managers at multiple levels within the EPA organization.
In keeping with the "work in progress* approach to the risk characterization meeting
series, the B2 colloquium/roundtable built on experiences and suggestions from previous
meetings. For example, the format for the meeting grew out of suggestions that the risk
assessor/risk manager relationship be thought of as a bridge that facilitates and enhances the
work of both parties rather than being constrained by a steel dividing wall. Similarly, the
meeting format was also shaped by two other recurring themes heard in previous meetings: the
utility of conducting a problem formulation step in human health and ecological risk assessments
alike, and the need to address concerns about cumulative risk. To fold the?e issues into this and
future risk characterization colloquia, meeting organizers added a presentation on how to begin
addressing cumulative risk in the problem formulation stage of risk assessment As hoped, the
meeting brought together disparate groups and perspectives, providing a forum for collaboration,
agreement, and disagreement
THE JUNE 1996 SERIES Cl COLLOQUIUM
The Series C Colloquium on Risk Characterization ("Meeting Cl") held on June 6 and 7,
1996, in Bethesda, MD, was the fourth meeting conducted under the risk characterization
meeting plan. As such, it incorporated all the features described above to provide the most
productive circumstances possible for discussing case studies from OSWER and EPA regions as
well as one cosponsorcd by OW and ORD. Indeed, the meeting proved to be fruitful in
identifying issues involved in using the preliminary implementation statements prepared by EPA
offices and regions.
To provide context and stimulate discussion, members of the SPC began the colloquium
by summarizing the history of risk characterization within the Agency, describing the major
objectives of the current risk characterization policy, outlining EPA's plan for implementing the
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policy (summarized above), noting a few of the issues and ideas that arose during the previous
colloquia, and providing an overview of issues related to cumulative risk in problem formulation
(see section 2). The case study presenters then offered a brief overview of their cases:
• Lavaca Bay, a preliminary assessment conducted by Region 6 to investigate the
ALCOA (Point Comfort)/Lavaca Bay Superfund Site and develop a
comprehensive assessment plan under the Superfund Amendments and
Reauthorization Act of 1986 (SARA).
• Midlothian, a cumulative risk assessment conducted by Region 6 to support the
State of Texas's consideration of an application by a cement kiln to burn
hazardous waste as fuel.
• Biocrude, a multimedia baseline risk assessment conducted by the Office of Solid
Waste (OSW) to determine whether biocrude should be listed as a hazardous
substance under the Resource Conservation and Recovery Act (RCRA).
• Waquoit Bay Watershed, an ecological risk assessment initiated in part by
Region 1 and cosponsored by OW and ORD to demonstrate the value of
ecological risk assessment for community-based efforts to protect ecological
resources.
After meeting in an opening plenary session to hear this background information,
colloquium attendees participated in breakout group discussions of the case studies. Two
breakout sessions were held (see agenda hi appendix A), enabling each attendee to hear and
discuss two case studies. Following the breakout sessions, the attendees reconvened in a plenary
session to discuss the major issues they had identified. As at previous meetings, opinions were
diverse, reflecting the diversity of the attendees, who represented many offices and regions across
EPA (see attendee registration list in appendix B).
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SECTION TWO
OPENING PLENARY SESSION
INTRODUCTORY PRESENTATIONS
Penelope Fenner-Crisp, Deputy Director of OPP and a member of the SPC, chaired the
Colloquium on Risk Characterization. She welcomed the attendees, offered some introductory
remarks, and introduced members of the SPC Steering Committee and Risk Characterization
Policy Implementation Team (Margaret Stasikowski, Jack Fowle, Ed Ohanian, Kerry Dearfield,
Mary McCarthy-O'Reilly), who played a major role in organizing the colloquium. Some of these
individuals also offered comments and background information.
In describing what EPA is striving for in its risk characterizations, the speakers often
referred to Administrator Browner's call for greater transparency, clarity, consistency, and
reasonableness (TCCR) in Agency risk assessments. They pointed out that TCCR also stands
for—and is a vehicle for accomplishing the overriding goal of being—Totally Clear and
Completely Responsible in risk characterizations. The speakers emphasized that it is in the
Agency's best interests (i.e., to ensure sound decision-making and avoid surprises) for risk
characterizations to be as realistic and unbiased as possible. They noted, too, that the public is
interested not only hi the risk information that EPA develops, but in how EPA arrives at its
conclusions. Thus, TCCR is important not just internally, but externally as well, to ensure that
the Agency can fulfill its mission responsibly.
The speakers acknowledged that achieving TCCR can be challenging. They stated that
some EPA offices have begun developing checklists and tips for meeting this goal. As an
example, they displayed one such tool, a list of "seven steps to better risk characterizations"
developed by OPPT (see figure 3).
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Risk Characterization Statement
Seven Steps to Better Risk Characterizations*
1. Indicate the Scope of the Assessment (Match Level of
Effort to the Scope.)
2. Summarize the Major Risk Conclusions and the Level of
"Comfort" the Risk Manager May Place in the Conclusions
3. Identify Key Issues. (A Key Issue is Critical to Properly
Evaluate the Conclusions.)
4. Clearly Describe the Methods Used. (Give Qualitative
Narration to Quantitative Results.)
5. Summarize the Overall Strengths and Major Uncertainties
6. Put this Assessment into a Context with Other Similar
Risks
7. Identify Other Important Information About the
Assessment
From the OPPT Risk Characterization Training Course
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Figure, 3. ..OPPT'S seven, steps to Better -risTr characterizations.
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CUMULATIVE RISK IN PROBLEM FORMULATION
After these introductory remarks, Penelope Fenncr-Crisp and the other speakers
introduced Ed Bender, who introduced the attendees to EPA's Cumulative Risk Project and
invited the attendees to contribute ideas and suggestions during and after the meeting.
Ed Bender began his presentation by explaining that the Cumulative Risk Project is an
attempt to broaden the scope of what EPA does—and what EPA is capable of doing. EPA
hopes that developing the cumulative risk concept will have the added benefits of improving risk
assessor/risk manager communication and facilitating discussions with the public about what EPA
is and is not doing and why. Cumulative Risk Project participants began by drafting a broad
definition of cumulative risk: risks from one or more stressors considered in aggregate. In
developing this definition, the group noted that addressing cumulative risk involves asking
question about who is affected/stressed, what are the stressors, what are the sources, what are
the pathways, what is the time frame for the risk, and what are appropriate assessment
endpoints.
Cumulative Risk Project participants are working to establish a framework for formally
defining the problem—that is, a conceptual model for cumulative risk problem formulation. The
group hopes that coordinating the effort to advance cumulative risk problem formulation with
risk characterization policy implementation activities will provide an opportunity for synergism,
enabling those working on the Cumulative Risk Project to take advantage of risk characterization
ideas and case studies and vice versa. In this way, discussing cumulative risk hi problem
formulation at this and future risk characterization colloquia should help (1) advance
understanding of cumulative risk problem formulation and (2) ensure that risk characterization
practices both conform to the current state of the science and facilitate progress in the practice
of cumulative risk assessment Ultimately, EPA will develop separate case studies to define the
practice of cumulative risk assessment, conduct separate workshops to define potential uses and
research needs, and develop separate guidance and implementation policies.
In the meantime, Cumulative Risk Project participants have drafted a preliminary
cumulative risk framework that proposes an interactive, iterative process for addressing
cumulative risk (see figure 4). This framework begins with problem formulation, when risk
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Cumulative Risk Frame
•nd Six* ***&*
Ha*
Figure 4. Draft cumulative risk framework.
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assessors and risk managers define the scope of a cumulative risk assessment by deciding what
can and will be addressed (i.e., by identifying management goals and values, the context of the
risk, questions to be answered, available resources, participants). Hie framework features a great
deal of interaction throughout the process; in fact, arrows were added to the framework diagram
based on feedback received during the risk characterization meeting (Meeting B2) held just the
previous week.
To facilitate cumulative risk problem formulation, Cumulative Risk Project participants
have also drafted a cumulative risk matrix that can be used to identify all possible assessment
endpoints; risk assessors and risk managers can then use this list to match assessment endpoints
to the management goal (see handouts in appendix C). By the end of the problem formulation
step, risk assessors should understand the risk manager's goal and what endpoints will generate
the types of information that will be most useful to the risk manager. The risk manager, in turn,
should have a preliminary sense of the problem and how it will be assessed—preliminary
information on the scope of the risk, what data are needed, what data are available, who can
help, schedule and resource requirements, knowledge gaps, and public concerns.
EPA recognizes that cumulative risk assessment has to date been limited by statutory
constraints, a lack of models for combining risks, a lack of information on unregulated sources of
risk, and resource constraints. Nevertheless, the Agency would like to determine what progress
can be made now. To that end, Ed Bender asked the attendees of this meeting to (1) apply the
cumulative risk problem formulation framework to the case studies under discussion, (2)
brainstorm a list of possible risk factors, (3) discuss the implications of these risk factors, and (4)
identify cumulative risk problem formulation guidance/policy needs.
CASE STUDY OVERVIEWS
Following these introductory remarks, case study authors from EPA offices and regions
introduced the attendees to the four cases prepared for this meeting. The cases were discussed
in greater detail in breakout sessions (see section 3).
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Lavaca Bay
Janinc Dinan, an Environmental Health Scientist in Region 6's Superfund program,
presented a brief overview of the Lavaca Bay case study. For context, she began by explaining
that the Superfund program deals with uncontrolled hazardous waste. The program is charged
with examining the contributions of individual facilities to contamination and exposure problems.
In so doing, risk assessors must examine the multiple chemicals and multiple exposure pathways
associated with the facility. In that sense, all Superfund risk assessments deal with cumulative
risk. On die other hand, the program historically has focused on individual facilities rather than
analyzing the cumulative risk posed by multiple sources (facilities) in the same area.
In this case, the site under examination consists of about 3,500 acres of an active
owned by the Aluminum Company of America (ALCOA), a 400-acre dredge spoil island created
by ALCOA, and portions of Lavaca Bay that could encompass an area as large as 60 square
miles. In 1988, the Texas Department of Health issued a fishing advisory dosing an area of
Lavaca Bay to the taking of finfish and shellfish due to mercury contamination. Region 6
conducted a preliminary risk assessment to characterize environmental conditions and the nature
and extent of contamination at the site, resulting in the addition of the site to the National
Priorities List (NFL), the list of Superfund sites slated for remediation.
Region 6 used the preliminary risk assessment to develop a Preliminary Site
Characterization Report and the first of two work plans for a baseline risk assessment The first
work plan presents methods to be used to determine the prevalence of recreational and
commercial fishing in general, as well as the seasonality (if any) of fish locations in Lavaca Bay.
Issues to be addressed include who will be at risk from mercury contamination, whether the
reference dose (RfD) for mercury is germane to this situation given site conditions, and whether
default fish consumption rates are adequate or alternative ingestion rates are required.
Janine Dinan emphasized that Region 6 is making every effort to make the process
understandable to everyone. To that end, it has produced a video on the project and is
interested in meeting participants' input on the Preliminary Site Characterization Report
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Midlothian
Jeffrey Yurk, a lexicologist in the Multimedia Planning and Permitting Division of the
Oklahoma/Texas RCRA Permits Section of Region 6, presented a brief overview of the
Midlothian case study. This case involves a risk assessment conducted to support the State of
Texas's consideration of an application by a cement kiln to burn hazardous waste as fuel. Under
RCRA, all permits are required to be protective of human health and the environment. Under
the Hazardous Waste Minimization and Combustion Strategy announced by EPA in 1994, risk
assessments are conducted to determine whether permit conditions will be protective. The
Midlothian case began as a screening level assessment focusing on human health, but evolved
into an intermediate assessment when Region 6 sought additional data to determine the
significance of potential risks identified during the initial analysis. Moreover, the case is an
example of a cumulative risk assessment because it not only examines the impact of the applicant
(the cement kiln operator), but considers the cumulative risk associated with all major facilities
(total of three combustion facilities and one steel mill) in the Midlothian area.
To conduct the assessment, Region 6 characterized the study site (the Midlothian area)
and used models to analyze plumes of contamination resulting from emissions from the
combustion facilities and steel mill; where the plumes overlapped, Region 6 added them to
characterize total contaminant levels. In this way, Region 6 identified maximum exposure points
(located around each facility) and selected receptors near those points. The analysis yielded
hazard indexes (His), some of which were greater than one. Due to a number of uncertainties
(accuracy of modeled numbers, data gaps, use of surrogate data, etc.), Region 6 returned to the
area to obtain measured data and other information to evaluate the reasonableness of the results
of the initial analysis. The measured values were less than the modeled values, leading Region 6
to conclude that exposure levels and risks are probably lower than levels of concern. Region 6
also analyzed the relative contributions of the studied sources, concluding that the steel mill
(which is outside the program's jurisdiction) is the major contributor to total exposure/risk levels.
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Biocrude
Becky Daiss, an Environmental Protection Specialist with OSW, presented a brief
overview of the Biocrude case study. The case study consists of a multimedia baseline risk
assessment conducted to determine whether biocrude (a hypothetical waste stream) should be
listed as a hazardous waste under RCRA. Under RCRA, a waste is considered hazardous if it
exhibits one of four hazardous characteristics (ignitability, corrosivity, reactivity, toricity) or is
already listed as hazardous in RCRA regulations. To make Hazardous Waste Listing
Determinations, OSW conducts multimedia baseline risk assessments. This case is an example of
a cumulative risk assessment in that it considers multiple waste constituents and pathways; hi
addition, it examines risks to both human health and the environment (in separate components).
Like other OSW baseline risk assessments, this case draws on a significant amount of
facility-specific information (waste characteristics, disposal practices) and general information
about the area (meteorological conditions, types and locations of receptors, soil characteristics,
exposure durations and frequencies). OSW identified several areas of uncertainty in the human
health and ecological risk assessments (biotransformation, effectiveness of runoff controls,
biotransfer factors, use of individual-level benchmarks and generic ecosystems, etc.), highlighting
those most likely to affect the recommendation to list biocrude as a hazardous waste. OSW
attempted to write the case study in a way that would make the risk assessment's scope and
focus, risk conclusions, and key limitations and uncertainties dear to a range of audiences—up to
and including risk managers and decision-makers.
Waquoit Bay Watershed
Suzanne Marcy, a Senior Scientist for Ecology with ORD's National Center for
Environmental Assessment (NCEA), presented a brief overview of the Waquoit Bay case study.
She began by explaining that this case study differs from the others in two ways: it is a problem
formulation product rather than a risk characterization, and it was initiated by community
interest rather than statutory requirements. Groups concerned about the changing quality of the
Waquoit Bay submitted a proposal to EPA suggesting that the bay be the subject of one of the
case studies EPA is seeking to develop on the application of ecological risk assessment principles
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to -watershed problems. The project is intended to expand die process of ecological risk
assessment and demonstrate its value for community-based efforts to protect ecological
resources. OW and ORD, cosponsors of the project, undertook an extensive problem
formulation effort to define the problem and plan the risk assessment with significant community
involvement In so doing, they strove to achieve many of the goals and criteria discussed in
Administrator Browner's risk characterization policy and EPA office/regional implementation
statements.
The Waquoit Bay Watershed is a small estuary with fresh water ponds and streams on the
south coast of Cape Cod in Massachusetts. Subject to many stressors (nutrients, toxics, altered
flow, suspended sediments, disease, habitat alteration, harvest pressure), the watershed is showing
many signs of deteriorating quality (replacement of eelgrass by mats of macroalgae, fish kills,
disappearance of scallops, contamination, etc.). To help define the problem, OW and ORD
developed a conceptual model (see figure 5) listing activities in the watershed, their associated
stressors, the ecological effects associated with these stressors, assessment endpoints, and
measures used to evaluate the endpoints.
In this case, OW and ORD identified assessment endpoints not by considering a facility or
chemical of concern (as is typically done in traditional assessments), but by convening public
discussions about watershed quality issues of concern to the community. Specifically, OW and
ORD held discussions with risk managers (broadly defined to include all interested parties in the
community and elsewhere) to develop a general management goal, which they broke down into
management objectives and assessment endpoints.
In providing this overview of the case study, Suzanne Marcy reiterated that the case's
problem formulation process and product are generally consistent with the goals being developed
for risk characterizations. In particular, OW and ORD strove to achieve TCCR; she and the
other case study presenters are interested in feedback on how they did in this regard.
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SECTION THREE
BREAKOUT SESSIONS
The opening plenary session was followed by two breakout sessions designed to give the
attendees an opportunity to explore risk characterization issues—and die practical issues involved
in using the various offices' and regions' preliminary implementation statements—in the context
of the four case studies (Lavaca Bay, Midlothian, Biocrode, Waquoit Bay Watershed). For each
breakout session, the attendees divided into four groups. In these groups, they heard a brief
presentation of a case study (one case study per group), then discussed the case study at length.
Each attendee was randomly assigned to one group during the first breakout session and to a
different group during the second breakout session, providing an opportunity to hear about and
discuss a total of two of the four case studies. Case presenters, chairs, and facilitators for these
sessions are listed in appendix D, while case study handouts are reproduced in appendix E and
the preliminary implementation statements are reproduced in appendix F. Background materials
on EPA's risk characterization policy are provided in appendix G.
The paragraphs below summarize the main points discussed in the breakout sessions.
Although not specifically noted in the summaries below, numerous attendees thanked the case
study presenters for their hard work in preparing their case studies and for their willingness to
present the case studies in this colloquium series.
LAVACA BAY
Following breakout group participant introductions, the case study presenters offered a
summary of the assessment conducted at the Lavaca Bay Superfund site. Although
contamination at Lavaca Bay is not limited to mercury, mercury is the primary contaminant of
concern and an intermediate level risk assessment was completed to evaluate human health risk
from exposure to mercury through fish consumption. An ecological risk assessment is being
conducted separately. The case study presenters posed several issues for discussion:
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Default fish consumption rates were used to estimate human exposure to methyl
mercury for fish and shellfish from Lavaca Bay. Are the defaults appropriate for
the exposed populations? Would the development and use of site-specific
consumption rates provide better information?
The current RfD for methyl mercury was used for the assessment. Is the RfD (in
particular, the uncertainty factors) applicable to this assessment? Would the use
of new data be more appropriate and reduce the uncertainty associated with the
Lavaca Bay assessment?
What limitations are there to quantifying cumulative risk at the site?
Does the risk characterization provide sufficient information for the risk manager
to make a sound, reasoned decision?
Breakout group participants felt that the presenters had done a good job in (1) satisfying
the risk characterization policy goals of TCCR and (2) following Region 6's preliminary
implementation statement. The participants also offered a few suggestions for enhancing the
characterization. They felt that the risk characterization's description of the scope of the risk
assessment could be improved by including an explanation of why this limited assessment was
done, what is currently being done, and what is in store for future assessments. The participants
could,not place the assessment precisely into any of the three categories outlined in Region 6's
preliminary implementation statement because the assessment seemed to have characteristics of
all three types (preliminary/screening, intermediate, baseline/complete). In addition to suggesting
that the scope of the assessment be clarified, the participants felt that the severity of the toxic
effects should be discussed and that there might be some value in providing an alternative
measure of toxicity, such as a margin of exposure (MOE). They also felt that adding tables and
charts would improve the clarity of the document.
The bulk of the discussion centered around what information should be provided to
enable the risk manager to make a good decision. Most participants felt that this information
should include key uncertainties, key messages, and key areas of comfort. The case study
presenters and the participants identified numerous uncertainties, but felt it important to focus
on those with the greatest impact on the assessment and those likely to be most visible or
controversial. The participants identified the following main points:
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It can be stated with little uncertainty that a real risk to average residents exists,
since the HI for mercury is high and tenacity studies are based on human data;
severity of effects is also important for making a decision. Consistent with EPA
policy and practices, the case study authors calculated the HI based on Superfund
guidance and the RfD for methyl mercury in EPA's Integrated Risk Information
System (IRIS). Uncertainties (e.g., the Seychelles Child Development Study,
background levels, ingestion rates) would not affect a decision to take action, but
could affect what action to take and the timing of the action.
The case study identifies highly exposed subgroups (Asian-Americans) and
sensitive subgroups (pregnant women). Determining the need for short-term
versus long-term action depends on identifying the population of most concern;
participants expressed some concern that highly exposed Asian-Americans may
not be protected.
This case involves "real people with real exposures." The critical exposure
pathway is fish ingestion. Assumptions about what people consume (e.g., big
versus small fish, fish versus shellfish, etc.) and how much they consume affect
fish ingestion rates, potentially resulting in a large under- or overestimate of
exposure. The case study authors derived (and a technical group agreed on)
defaults from several studies; additional site-specific surveys will also involve
uncertainties, but may provide better data on what the subpopulations really eat
Risk managers will need to weigh the risk associated with ingestion exposure to
mercury against the benefits associated with good nutrition (since fish is good
source of protein and true subsistence subpopulations do not have a choice of
what to eat).
An abundance of fish concentration data exists. Thus, there is no need for
additional data, although the data could be manipulated in different ways.
There is uncertainty in the significance of the site-related risk compared to the
risk associated with background levels of mercury. Currently, the Agency has no
single accepted method for determining background levels; hence, this may be an
area needing further guidance or research. Referencing other data, such as
National Oceanic and Atmospheric Administration (NOAA) numbers, provides
some confidence.
This preliminary risk assessment does not evaluate cumulative risk (the effect of
other dietary sources of mercury and other site contaminants). Nevertheless, this
assessment is sufficient to justify a decision to take action.
Action should be taken sooner rather than later because future events (e.g.,
future dredging operations and hurricanes) could worsen the mercury
contamination.
Breakout group participants also discussed questions and concerns that managers might
have: How sure are you that a risk exists? Some managers will want to reduce exposure now!
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What will risk reduction cost? What are the pros and cons of taking immediate action versus
waiting for new data? What uncertainties can be reduced? How quickly? At what cost? How
does this HI compare to measures used by other agencies (e.g^ FDA)? Has the existing fish
advisory had any effect? Is the level of risk likely to change hi the future due to hurricanes or
future dredging? Because risk managers have limited time, risk assessors need to focus on
critical messages and those uncertainties with the greatest impact
Breakout group participants felt strongly that the risk characterization cannot be
completed without management involvement and that an iterative approach needs to be taken to
refine the problem formulation, since social and legal issues involved in management decisions
also affect the certainty of risk characterization data. For example, because the Vietnamese
community is known to distrust government involvement, a survey may not accurately elucidate
the activities of this community. Similarly, shrimpers are known to keep the by-catch from their
shrimping, but may not report this activity because it might be illegal; this uncertainty brings into
question whether shrimpers will be protected by actions/limits that are based on survey data.
MIDLOTHIAN
The Midlothian breakout group sessions began with an overview of Region 6's preliminary
implementation statement (given by the session chair) and a description of the Midlothian risk
characterization (given by the case study presenter). Following these presentations, breakout
group participants (including Headquarters and regional scientists representing several programs)
exchanged ideas about risk characterization issues related to the implementation statement and
case study.
Region 6's preliminary implementation statement is a draft document developed by risk
assessors from several Region 6 programs and reviewed by risk managers and staff. The
document identifies and classifies regional risk activities as follows:
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• Category I: Screening Analyses (limited resources, little or no site sampling, use
of modeling).
• Category II: Intermediate Analyses (some monitoring and sampling, used for
permit-related activity, supported by regional guidance and national standards).
• Category HI: Baseline Analyses (extensive literature review and data
documentation, substantial resources used, site sampling and monitoring required,
regional and national regulations and guidelines followed).
The Midlothian assessment is a screening analysis, but has some features of an intermediate
analysis. It is a cumulative risk assessment in that it examines emissions from several sources
(three cement kilns and one steel mill) and analyzes multiple exposure pathways.
In discussing the implementation statement and case study, breakout group participants
agreed that all risk characterizations (regardless of level or category) must include a dear
statement of the assessment's scope and the reasonableness of its conclusions. For clarity and
transparency, expectations for the assessment (particularly if these expectations differ from what
is typically expected) should be stated up front When preparing screening level risk
characterizations in particular, EPA risk assessors cannot assume that the reader is aware of the
limitations (e.g., in data accuracy, certainty of conclusions) inherent in screening level
assessments.
Breakout group participants felt that risk characterizations should also identify the impacts
of "external forces" on the assessment. For example, several sections of the Midlothian case
study were affected by omissions or absence of data—data on organic emissions from the steel
mill were unavailable, and the dermal exposure pathway was not assessed. Most participants felt
that information gaps, data limitations, and analytical judgments such as these should be highly
visible in the risk characterization document
With regard to the risk assessor/risk manager relationship, the breakout group participants
felt that a bright line should separate risk assessment from risk management Some participants
supported this contention by citing instances in which risk assessors felt pressure from risk
managers intent on finding a specific result The participants agreed that scientific integrity must
be preserved, and they suggested that the risk characterization process helps maintain an
appropriate line between science and management issues. Even so, some issues remain unclear.
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For example, questions surfaced as to where cost-benefit and socioeconomic issues fall in "the risk
assessment/risk management continuum; these data are required for comprehensive risk
characterizations, but move very close to the risk management side of the fence.
Breakout group participants also discussed whether a single risk characterization format
could meet the needs of all audiences (all the various interested risk assessors and managers).
Most agreed that Headquarters and regional offices differ in their risk characterization needs.
For example, regional risk characterizations are often presented to the public early on—a fact
that surprised some attendees from Headquarters. In addition, risk characterizations are
sometimes used as briefing documents. The participants discussed whether risk characterizations
are (or should be) standalone documents or chapters in a larger publication. The participants
did not resolve these questions about the ideal form(s) of risk characterizations.
Breakout group participants also offered the following recommendations and comments:
• Risk characterizations should clearly state where the assessment is thought to be
conservative and where it may be less protective.
• Even if the risk characterization cites EPA's Exposure Factors Handbook, it should
still explain the rationale for the exposure parameters and assumptions selected.
• The cumulative risk matrix should be used early in the risk characterization
process.
• Risk managers and assessors do not always see or have guidance to assess risk
from a multiprogram perspective (Superfund, air, non-point source). This can be
a barrier to cumulative risk analysis.
• Users of computer-assisted risk analysis models (risk-based corrective actions,
geographic information systems) can benefit from risk characterization
documentation.
• When appropriate, a range of possible lexicological outcomes should be given for
important site contaminants.
• Risk characterizations should reference important reports from states or other
federal agencies.
• In preparing risk characterizations, risk assessors should translate risk jargon into
understandable language (e.g., 60 grams/day of fish translates to about 2 fish
meals/week).
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Risk assessors will need technical guidance and resources (e.g., statistical
uncertainty analyses, socioeconomic evaluations) before achieving many of the
desired risk characterization goals.
Risk characterization training is needed for all levels of EPA staff (e.&,
Superfund Remediation Project Managers, On-Site Coordinators, branch and
section managers).
BIOCRUDE
Breakout group participants agreed that risk characterization concepts are needed and
useful and that the risk characterization process involves a spectrum of activities producing a
spectrum of products. With respect to the case study, the participants felt that the OSW case
study authors did an good job, going far above and beyond the call of duty given that they
developed their case study exclusively for this colloquium. Ordinarily, OSW does not produce
standalone risk characterizations, but includes such information in risk assessment preambles and
briefing packages developed for various purposes and presented to various managers.
Breakout group participants felt that the case study generally meets the goals of TCCR,
giving the characterization an overall rating of 7 on a scale of 1 to 10 (10 being the best) and a
rating of 9 in terms of their confidence that the case does not underestimate the true risk.
Recommendations for improvement centered on the need to better categorize the strengths of
the assessment and the need to include comparisons to other similar environmental risks.
Most participants felt that OSWs preliminary implementation statement would be read
only by those who wrote it and by large potentially responsible parties (PRPs) who want to use it
to undermine EPA decisions. The participants agreed that the preliminary implementation
statement is "too stuffy" and is not helpful; Simpler guidance (e.g^ a checklist) on when, where,
and how to apply risk characterization policy principles would be received much more favorably
and would be much more likely to be used. The implementation statement could be a reference
document, however, serving as a training resource for new employees and as a means of helping
communicate Administrator Browner's policy.
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A starting point for a simpler implementation statement might be the list of questions that
the participants identified as questions that regional risk managers typically ask:
• How confident are you in the assessment?
• Is this reasonable (given current and potential future uses)?
• Do "others* agree with the assessment?
• Have you coordinated across media? Statute?
• Is there a problem?
• What are the pros and cons of taking action versus waiting for more data?
• What uncertainties can be reduced? How quickly? At what cost?
Breakout group participants attempted to discuss cumulative risk as Ed Bender requested
(see section 2), but felt confused about how this topic relates to risk characterization and
whether we ought to pursue cumulative risk at all. Participants from EPA regions expressed
many concerns about both cumulative risk and risk characterization, including:
• Managers do not want to do it
• The Administrator and Deputy Administrator are not really serious about it.
• Managers are just looking for the number from standard Agency publications;
managers do not really use science in their decisions.
• The cumulative risk issue adds to the uncertainties, which both increases the
demand for more cleanup and leads some people to question whether a risk exists
at all. This makes EPA staff feel bad (that their work is not important) and
adversely impacts morale.
• Addressing cumulative risk creates the false impression that EPA is a full service
public health agency. On the other hand, the problem formulation step envisaged
for cumulative risk does give people more information about lifestyle choices, and
this can lead to better health. The "person on the street" does not care which
part of government or which office in EPA deals with a problem—he/she merely
wants tax dollars to be used wisely and assurance that the government will look
for efficient ways to tackle the problem. The problem formulation process laid
out in the cumulative risk activity provides a mechanism for teasing out the
problem and searching across departments for the best solution.
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WAQUOIT BAY WATERSHED
The Waquoit Bay case study, one of the first to address ecological risk assessment,
consists of a problem formulation document prepared for an assessment of Waquoit Bay
watershed ecological issues. Breakout group participants reviewed the problem formulation and
commented on how well the authors achieved TCCR. Hie Waquoit Bay case study served
primarily as a basis for discussion; most of the breakout group's comments apply to ecological
risk assessment in general rather than to this case study in particular.
Transparency and Clarity
Breakout group participants felt that the decisions goals in the problem formulation are
well articulated (i.e., transparent). Moreover, the document dearly identifies the linkages
between and rationales for the various steps in the assessment To further enhance the
transparency of the decisions, the group suggested adding explanations or clarifications oft
• Factors that motivated the various participants (individuals and groups) to
become involved.
• The bias associated with the affiliations of team members.
• The aims of the group formulating the problem.
• Assumptions, policies, and decisions that were discarded.
• The influence of resource issues on decisions.
• The transition from' goals to objectives to key issues selected for evaluation.
• The amount of data needed for the assessment
• The limitations of methods selected for analysis of exposure and effects.
The group also suggested:
• Adding more definitions of terms for the general public
• Simplifying the conceptual models
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m Adding a flow chart of decisions
• Faring inconsistencies between the appendix and text
Consistency and Reasonableness
Breakout group participants noted that the acceptability (reasonableness) of goals depends
on who is judging them. This is particularly apparent in watershed ecological risk assessments
designed to bring all parties to the table.
Breakout group participants also discussed whether the definition of "reasonable" is
consistent across EPA programs. Participants felt that maintaining consistency in assumptions
and policies is difficult due to the complexity of ecological risk assessments—in which, for
example, an upper bound worst case or most likely scenario cannot easily be defined. These
parameters are extremely variable and depend on the level of biological organization being
evaluated as well as the availability of data to establish bounding limits on exposure estimates.
The concept of natural recovery further complicates attempts to develop reasonable risk
estimates: can ecosystems ever return to some predetermined condition, or are systems
constantly evolving so that we must simply select some point that we consider ecological sound?
In ecological risk assessment, even establishing consistent core assumptions is difficult
Whereas management and assessment values are clearly distinct and often predetermined by
statute in human health risk assessment, these values are often less clear in ecological risk
assessments. For example, EPA has no prescribed method for defining watershed boundaries;
these are generally defined by the user. Is consistency in watershed boundary definitions in
problem formulations important? Similarly, in ecological risk assessment, the assessment
endpoint is both an entity and an attribute—and the entity can be defined in any number of ways
(e.g., salmon, dams, spotted owls, a marsh, an estuary) rather than always being the same
(humans). What constitutes consistency in defining the entity?
With regard to consistency and reasonableness, breakout group participants also noted the
following:
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Maintaining consistency is difficult when risk assessments are shaped by different
(inconsistent) statutes.
By virtue of the breadth of their issues and goals, ecological assessments will be
inconsistent
Ecological risk assessments should be consistent in terms of process, but different
in terms of specific issues and goals.
Other Recommendations and Comments
Several additional issues arose during the breakout group's discussion of the Waquoit Bay
case study:
Terminology. Human health and ecological risk assessments use different
terminology. EPA should identify and harmonize terminology differences.
Exposure assumptions. Core exposure assumptions are generally relatively simple
hi human health risk assessment (e.&, a residential scenario primarily involves
ingestion), but much broader hi watershed risk assessment (e.g., the assessment
must consider nutrients, eutrophication, food chain dynamics).
Measures of exposure. The process of developing a conceptual model, analysis
plan, and risk hypothesis is designed to help the risk assessor determine the best
assessment endpoints and measures of exposure and response. For ecological
entities, however, selecting measures of exposure is complex. How does the
assessor determine which pathways, stressors, or activities are important?
Problem formulation. Problem formulation adds value to the risk assessment
process because it forces a discussion between managers and assessors at the start
of the assessment Because the quantity and quality of available data influence
assessment results, such a discussion can help bring the manager's (or the
public's) expectations in line with likely results. Identifying areas of high
uncertainty is especially important so that managers recognize when they will
need to make hard decisions with little information. Some decisions can be made
with a large degree of uncertainty, while others can wait until uncertainty is
reduced. These issues need to be discussed with decision-makers at the outset to
ensure that they understand the feasibility of their expectations. Similarly,
problem formulation adds significant value in forcing scientists/risk assessors to be
explicit about their assumptions and level of understanding. Planning forces
scientists to interact with managers.
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Concluding Remarks
A framework and process for risk management are definitely needed. Difficult cases
should be debated so that issues are raised in the context of a process that will yield criteria for
how to proceed with the analysis and ultimate characterization.
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SECTION FOUR
CLOSING PLENARY SESSION
GENERAL COMMENTS ON IMPLEMENTATION STATEMENTS AND CASE STUDIES
Following lively breakout group discussions, the attendees reconvened in a plenary session
to talk about their reactions to the discussions and to review cross-cutting issues. In general, this
portion of the meeting focused on how to treat uncertainty in risk characterizations, whether and
how the implementation plans and case studies are useful, how to apply TCCR to other inputs
into decision-making (and to decision-making itself), how to deal with cumulative risk, and what
progress can be made in the short versus long term.
Treatment of Uncertainty
Dealing with uncertainty was the topic of some discussion, with some attendees feeling
that they and their colleagues are still grappling with what constitutes an adequate treatment of
uncertainty in risk assessments. One attendee commented that some of the resistance to the new
risk characterization policy in the regions derives from a concern about how to deal with
uncertainty without jeopardizing decisions. In particular, many risk assessors and risk managers
are concerned that PRPs will use uncertainty information to undermine decisions. In addition,
many risk assessors have questions about when Monte Carlo is necessary, what value it adds, and
whether simply expanding uncertainty discussions (rather than addressing it in a focused way
based on well developed guidance) is really desirable.
One attendee felt that the colloquium had been useful in providing a different perspective
on the use of uncertainty, opening the possibility that uncertainty can be turned around to
express degree of confidence in an assessment Another attendee agreed, suggesting that risk
characterizations can be used from a position of strength when they include balanced
articulations of strengths as well as limitations and uncertainties.
4-1
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DRAFT—DO NOT COPT, DISTRIBUTE, OR QUOTE.
Usefulness of Implementation Statements and Case Studies
Asked if they felt that the office and regional risk characterization implementation
statements are useful, the attendees identified several benefits to their development and use:
• An organized method for addressing risk characterization issues helps make the
entire process more scientific, thereby reducing uncertainties.
• Developing the implementation statements forced people to ask questions that
they might not otherwise have considered. Rather than maintaining the status
quo, therefore, risk assessors are more thoughtfully considering important
questions (e.g., who are we trying to protect?).
• Similarly, discussion of the implementation statements is highlighting the need to
clarify the roles of risk assessors and risk managers—and, in particular, is pointing
to the need for greater interaction/collaboration early in the process (e.g., during
problem formulation).
• Having the implementation statements also provides an opportunity for EPA to
ask that external risk assessors apply the same rigor to their risk assessments (i.e.,
those that they present to the Agency) as internal risk assessors do to theirs.
Several attendees commented that a lack of communication between risk assessors and
risk managers hampers effective use of the implementation statements. When risk assessors and
risk managers do not communicate early on, risk managers receive assessment information only
at the last minute, making it difficult to understand or take in all relevant information. These
observations led to a discussion of what is realty important for real-world decision-making. For
example, one attendee speculated that if a risk assessor fully complied with the risk
characterization policy and brought a complete characterization to the risk manager, the risk
manager would still respond with the question "With all your experience, what do you think?"
Summing up comments that he had heard during breakout group discussions, one attendee said
that, whether or not they articulate them in this way, risk managers seem to focus on the
following questions:
• How confident are you in the assessment?
• Is the conclusion reasonable (given real-world uses and potential future uses)?
• Do others agree with the assessment?
4-2
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
• Is there a problem?
• How does it compare to others?
• What are the pros and cons of taking action now versus waiting for more data?
• What uncertainty can be reduced? How quickly? At what cost?
Another attendee agreed, stating that a checklist of this sort might be more practical than the
lengthy implementation statements that have been developed. Several attendees supported the
idea that some type of checklist would be useful, and also suggested that the implementation
statements be simplified
Some attendees commented that the case studies, too, are more comprehensive than
necessary. In particular, it would be useful to have a range of case studies (not just "cadillacs")
to match the range of risk assessments/risk characterizations actually conducted in program
offices and the regions. One attendee felt that beginning with the "cadillacs" was useful in
facilitating in-depth exploration of risk characterization issues; the feedback generated during
these case study discussions, he said, would be helpful as the Agency begins to develop case
studies for less comprehensive efforts. Another attendee noted that the case studies discussed at
this colloquium served to highlight the fact that different levels of documentation are needed for
different circumstances.
Other Opportunities for Applying TCCR
Several attendees supported the need for TCCR in risk characterizations, but felt that the
same standards should be applied to other information given to decision-makers—and to the
derisioq-making process itself. They felt that people inside and outside of EPA will continue to
have questions about Agency decisions until TCCR is consistently applied to all aspects of the
decision-making process, from beginning to end. Penelope Fenner-Crisp, the colloquium chair,
displayed a diagram of inputs into risk management decisions (see Figure 6) and asked whether
the attendees believe that TCCR should be applied to all boxes in the diagram. Several
attendees responded affirmatively. Stating that he had heard one risk .manager say that he
receives clearer answers from the other groups depicted hi the diagram than he does from risk
4-3
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t
Economic
Characterization
Value*
Characterization
Risk
Assessment
Legal ft Statutory
Characterization
Ri.k
Characterization
Decision
Social Factor*
Characterization
Political Factor*
Characterization
Figure 4. Inputs into the decision-makinn process.
-------
DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
assessors, one attendee felt that it is no wonder, since those groups are not held to the same
level of rigor and scrutiny. Another attendee agreed, suggesting that applying TCCR consistently
might help bring the various inputs into balance.
Cumulative Risk
Stating that the issue of cumulative risk had initially seemed formidable, some attendees
commented that they felt encouraged by colloquium discussions on this issue. One attendee
stated that the perception had been that EPA is asking risk assessors to describe, characterize,
and add all risks into a holistic cross-medium picture of total risk. This, he felt, was unrealistic
at the present time. He was encouraged to learn that the Agency is initially seeking to
understand the risk associated with a particular faculty/chemical/issue and how that risk compares
to other sources of risk in the area—and that only gradually will the Agency add complexity by,
for example, initiating cooperative cross-program projects to consider in a holistic fashion how
the Agency can best reduce risk. Another attendee noted, however, that some opportunities for
hoUstic/CToss-program/cumulative risk assessment exist now, he suggested taking advantage of
opportunities, when available, to work with (or even defer to) other programs or agencies and to
spotlight risk issues outside one's own jurisdiction that other groups might be able to address.
Short-Tenn Versus Long-Term Goals
Several attendees alluded to the difficulty of achieving full compliance with the risk
characterization policy, let alone fully incorporating concepts of cumulative risk, in a short time
frame. One attendee suggested that EPA identify what types of progress can be made quickly
versus what will take more time. In so doing, the Agency might speed progress in important
areas while larger or more complex issues are being resolved.
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
ADJOURNMENT
Following this discussion, Penelope Femur-Crisp thanked the attendees for their
contributions and closed the colloquium.
4-6
-------
Risk Characterization Colloquiun
C-l
The following attachments relate to the-Risk Characterization Colloquium
held in Bethesda, Maryland on June 6 & 7, 1996
Appendix A Agenda
Appendix B Attendee Registration List
Appendix C Cumulative Risk In Problem Formulation
Handouts
Appendix D Case Presenters, Chairs and Facilitators
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
APPENDIX A
AGENDA
-------
&EPA
United States
Environmental Protection Agency
Science Policy Council
Risk Characterization Colloquium
Series Cl: OSWER and Regions
Colloquium Chair: Penelope Fenner-Crisp
Holiday Inn Bethesda
Bethesda, MD
June 6-7, 1996
Agenda
THURSDAY, JUNE 6
PLENARY SESSION I
8:00AM Registration
9:00AM Welcome and Opening Remarks Penelope Fenner-Crisp
9:10AM Background on Risk Characterization
• March 21 Carol Browner Memorandum Margaret Stasikowski
• Points To Consider in Risk Characterization
and Risk Characterization Implementation Statements Jack Fo\v/e
9:45AM Cumulative Risk in Problem Formulation Ed Bender
10:OOAM Colloquium Program, Goals, and Next Steps Ecf Ohanian
10:1 SAM Overview of Case Studies
• Case Study A: Lavaca Bay Janine D/nan and Jon Rauscher
• Case Study B: Midlothian Jeffrey Yurfc
• Case Study C: RCRA Listing Determination for Waste
From the Production of Biocrude Dave Cozzie and Becky Daiss
Printed on Recycled Paper
A-l
-------
THURSDAY, JUNE 6 (Continued)
10:1 SAM Overview of Cose Studies - continued
• Case Study D: Waquoit Bay Watershed Suzanne Marcy
11 :OOAM Purpose of/Charge to Breakout Groups Penelope Fenner-Crisp
11:1 SAM BREAK
CONCURRENT BREAKOUT SESSIONS-I
11:30AM Breakout Sessions-!
• Case Study A: Lavaca Bay Session Chair: Dave Bennett
(OERR & Region 6) Facilitator: Ruth B/ey/er
Case Presenters: Janine Dinan and Jon Rauscher
• Case Study B: Midlothian {Region 6) Session Chair: Gerald Carney
Facilitator: Ed Ohan/an
Cose Presenter: Jeffrey Yurie
« Case Study C: RCRA Biocrude (OSW) Session Chair: Donald Barnes
Facilitator: Jack Fowle
Case Presenters: Dave Cozzie and Becky Daiss
• Case Study D: Waquoit Bay Watershed Session Chair: Margoref Sfasikowski
{OW & Region I) Facilitator: Pat drone
Case Presenter: Suzanne Marcy
12:30PM LUNCH
1:45PM Breakout Sessions-t (Continued)
3:15PM BREAK
3.-30PM Breakout Sessions-l (Wrap-Up)
4:30PM ADJOURN
A-2
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FRIDAY, JUNE 7
CONCURRENT BREAKOUT SESSIONS-II
8:30AM Breakout Sessions-li
• Case Study A: Lavaca Bay Jan/ne Dinan and Jon Rauscher
• Case Study B: Midlothian Jeffrey Yurk
• Case Study C: RCRA Biocrude Dove Cozz/e and Becky Daiss
• Case Study D: Waquoit Bay Watershed .... Suzanne Marcy and Patti Tyler
10:OOAM BREAK
10:1 SAM Breakout Sessfons-ll (Wrap-Up)
11:30AM LUNCH
PLENARY SESSION II
1 :OOPM Risk Characterization Issues
and Colloquium Wrap-Up Penelope Fenner-Crisp and Session Chairs
• General Feedback and Discussion
• Expectations, Outcome, and Next Steps
3:OOPM ADJOURN
A-3
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
APPENDIX B
ATTENDEE REGISTRATION LIST
-------
SEPA
United States
Environmental Protection Agency
Science Policy Council
Risk Characterization Colloquium
Series Cl: OSWER and Regions
Holiday Inn Bethesda
Bethesda, MD
June 6-7, 1996
Final Attendee List
Elmer W. Akin
Chief, Office of Health Assessment
Waste Management Division
U.S. Environmental Protection Agency
34$ Courtland Street, NE
Atlanta, GA 30365
404-347-1586 Ext: 6361
Fax:404-347-1918
E-mail: aWn.elmer@epamail.epa.gov
Marcia Bailey
Environmental Scientist
Office of Environmental Assessment
U.S. Environmental Protection Agency
1200 Sixth Avenue
Seattle, WA 98101
206-553-0684
Fax:206-553-0119
E-mail: bailey.marcia@epamail.epa.gov
Donald Barnes
Staff Director
Science Advisory Board
Office of the Administrator
U.S. Environmental Protection Agency
401 M Street, SW(t400)
Washington, DC 20460
202-260-4126
Fax: 202-260-9232
Tom Baugh
Environmental Scientist
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8623)
Washington, DC 20460
202-260-8936
Fax:202-401-8533
Gary A. Baumgarten
Environmental Engineer
Superfund Division
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-AT)
Dallas, TX 75202
214-665-6749
Fax: 214-665-6660
Cherri Baysinger-Daniel
Environmental Specialist
Bureau of Environmental Epidemiology
Missouri Department of Hearth
210 El Mercado Plaza
Jefferson City, MO 65102
573-751-6111
Fax: 573-526-6946
Printed on Recycled Paper
B-l
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Lynn Beasley
Region -4/10 Accelerated Response Center
Superfund/Oil Program
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
401 M Street, SW (5204.G)
Washington, DC 20460
703-603-9086
Jeff Beaubier
Epidemiologist
Health & Environmental Review Division
Health Effects Branch
U.S. Environmental Protection Agency
401 M Street, SW (7403)
Washington, DC 20460
202-260-2263
Fax: 202-260-1283
Edward Bender
Biologist
Office of Science Policy
U.S. Environmental Protection Agency
401 M Street, SW (8103)
Washington, DC 20460
202-260-2562
Fax: 202-260-0744
David Bennett
Senior Process Manager for Risk
Hazardous Site Evaluation Division
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
401 M Street, SW (5202G)
Washington, DC 20460
703-603-8759
Fax: 703-603-9100
E-mail: bennett.da@epamail.epa.gov
Robert Benson
Team Leader, Sustainable Industries
Office of Policy Development/
Industries Strategies Division
Office of Policy, Planning, arid Evaluation
U.S. Environmental Protection Agency
401 M Street, SW (2128)
Washington, DC 20460
202-260-8668
Ruth Bleyler
Environmental Scientist
Science Policy Council Staff
Office of Research and Development
U.S. Environmental Protection Agency
JFK Federal Building (HBS)
Boston, MA 02203
617-573-5792
Fax: 617-573-9662
E-mail: bleyler.ruth@epamail.epa.gov
Ethel Brandt
Biologist
Chemical Screening & Risk Assessment Division
Office of Pollution Prevention & Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7402)
Washington, DC 20460
202-260-2953
Fax:202-260-1216
Carole T. Braverman
Senior Risk Assessor
Office of Strategic Environmental Assessment
U.S. Environmental Protection Agency
77 West Jackson Boulevard (B-I9J)
Chicago, IL 60604
312-886-2910
Fax: 312-353-5374
E-mail: braverman.carole@epamail.epa.gov
Ann-Marie Burke
Regional Human Health Risk Assessor
Office of Site Remediation & Restoration
U.S. Environmental Protection Agency
90 Canal Street (HBS)
JFK Federal Building
Boston, MA 02203
617-223-5528
Fax:617-573-9662
E-mail: burke.annmarie@epamaii.epa.gov
Gerald R. Carney
Toxicologist
Office of Enforcement and Compliance
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-XP)
Dallas, TX 75202-2733
214-665-6523
Fax: 214-665-7446
B-2
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Steve Chang
Environmental Engineer
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
401 M Street, SW (5204G)
Washington, DC 20460
703-603-9017
Fax: 703-603-9103
David W. Charters
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
2890 Woodbridge Avenue
Edison, NJ 08837
908-906-6825
Fax: 908-321-6724
E-mail: charters.davidw@epamail.epa.gov
Haral Choudury
National Center for Environmental Assessment
U.S. Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7536
Patricia A. Cirone
Manager, Risk Evaluation Assessment
Office of Environmental Assessment
U.S.- Environmental Protection Agency
1200 Sixth Avenue
Seattle, WA 98101
206-553-1597
Fax:206-553-0119
David Cozzie
Regional Impact Analyst
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-0479
Fax:703-308-0511
David Crawford
Superfund Program
U.S. Environmental Protection Agency
726 Minnesota Avenue
Kansas City, KS 66101
913-551-7702
Becky Daiss
Environmental Protection Specialist
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-0506
Fax: 703-308-0511
Jim Darr
Chemist
Chemical Screening & Risk Assessment Division
Office of Pollution Prevention & Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7402)
Washington, DC 20460
202-260-3441
Fax:202-260-1216
E-mail: darT.james@epamail.epa.gov
Dana Davoli
Risk Assessor
Office of Environmental Assessment
U.S. Environmental Protection Agency
1200 Sixth Avenue
Seattle, WA 98101
206-553-2135
Fax:206-553-0119
E-mail: davoli.dana@epamail.epa.gov
Kerry L. Dearfield
Biologist
Science Policy Council Staff
U.S. Environmental Protection Agency
401 M Street, SW (8! 03)
Washington, DC 20460
202-260-4752
Fax: 202-260-0744
E-mail: dearfieid.kerry@epannail.epa.gov
B-3
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Arnold Den
Office of the Regional Administrator
U.S. Environmental Protection Agency
75 Hawthorne Street (H-9-3)
San Francisco, CA 94105
415-744-1018
Lois Dicker
Biologist
Chemical Screening & Risk Assessment Division
Office of Pollution Prevention & Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7402)
Washington, DC 20460
202-260-3387
Fax: 202-260-1216
Janine Dinan
Environmental Health Scientist
Region 2/6 Center
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
401 M Street, SW (5202G)
Washington, DC 20460
703-603-8824
Fax: 703-603-9133
William R. Effland
Environmental Soil Scientist
Environmental Fate and Effects Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
401 M Street, SW (7507Q
Washington, DC 20460
703-305-5738
Fax: 703-305-6309
E-mail: effland.william@epaniail.epa.gov
Penelope Fenner-Crisp
Deputy Director
Office of Pesticide Programs
U.S. Environmental Protection Agency
401 M Street, SW (7509Q
Washington, DC 20460*
703-305-7092
Michael P. Firestone
Science Advisor
Office of the Assistant Administrator
Office of Prevention, Pesticides,
and Toxic Substances
U.S. Environmental Protection Agency
401 M Street, SW (7101)
Washington, DC 20460
202-260-2899
Fax: 202-260-1847
E-mail: firestone.michael@epamatl.epa.gov
Jack Fowle
Science Advisory Board
Office of the Administrator
U.S. Environmental Protection Agency
401 M Street, SW(NOOF)
Washington, DC 20460
202-260-8325
Fax: 202-260-7118
Kevin Garrahan
Assistant Center Director
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8603)
Washington, DC 20460
202-260-2588
Fax: 202-401-1722
E-mail: garrahan.kevin@epamail.epa.gov
Joseph Greenblott
Environmental Scientist
Office of Research and Science Integration
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8104)
Washington, DC 20460
202-260-0467
Fax: 202-260-0932
E-mail: greenbiott.joseph@epamail.epa.gov
B-4
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Peter Grevatt
Environmental Scientist
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
290 Broadway
New York, NY 10007-1866
212-637-3526
Fax: 212-637-4360
Cynthia Hanna
Environmental Scientist
Chemical Screening and Risk Assessment Division
Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7402)
Washington, DC 20460
202-260-2853
Gerald F.S. Hiatt
Senior Risk Assessment Advisor
Super-fund Division
U.S. Environmental Protection Agency
75 Hawthorne Street (H-9-3)
San Francisco, CA 94105
415-744-2319
Fax:415-744-1916
E-mail: hiatt.gerald@epamail.epa.gov
J. William Hirzy
Senior Scientist
Chemical Screening & Risk Assessment Division
Office of Pollution Prevention & Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7402)
Washington, DC 20460
202-260-4683
Fax: 202-401-3139
E-mail: hirzy.john@epamail.epa.gov
Jennifer Hubbard
Toxicologist
Hazardous Waste Management Division
U.S. Environmental Protection Agency
841 Chestnut Building (3HW4I)
Philadelphia, PA 19107
215-566-3328
Fax: 215-566-3001
E-mail: hubbard.jennifer@epamail.epa.gov
Barnes Johnson
Acting Director
Economic Methods and Risk Assessment Division
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency-
40J M Street, SW (5305)
Washington, DC 20460
703-308-8881
E-mail: johnson.barnes@epamajl.epa.gov
Darlene Jones
Chemical Control Division/New Chemicals Branch
Office of Pollution Prevention & Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7405)
Washington, DC 20460
202-260-2279
Fax: 202-260-0118
Ghassan Khoury
Toxicologist
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue - Suite 1200
Dallas, TX 75202-2733
214-665-8515
Fax 214-347-4702
Stephen Kroner
Environmental Scientist
Economic Methods and Risk Assessment Division
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
401 M Street, SW (5304)
Washington, DC 20460
202-260-5219
Mark Maddaloni
Environmental Scientist
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
290 Broadway
New York, NY 10007-1866
212-637-4315
Fax: 212-637-3526
B-5
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Becki Madison
Chief, Waste Team
Office of Research & Science Integration
Office of Research and Development
U.S. Environmental Protection Agency
101 M Street, SW (8104)
Washington, DC 20460
202-260-5984
Fax: 202-260-0106
Amal Mourad Mahfouz
Senior Scientist
Health and Ecological Criteria Division
Office of Water
U.S. Environmental Protection Agency
40! M Street, SW (4304)
Washington, DC 20460
202-260-9568
Pax: 202-260-1036
E-mail: mahfouz.amal@epamail.epa.gov
Suzanne Marcy
Senior Scientist for Ecology
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8601)
Washington, DC 20460
202-260-0689
Fax: 202-260-0393
E-mail: marcy.suzanne@epamail.epa.gov
Elizabeth H. Margosches
Chief, Epidemiology &
Quantitative Methods Section
Health & Environmental Review Division
Office of Pollution Prevention & Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7403)
Washington, DC 20460
202-260-1511
Fax: 202-260-1279
Marial Martinez
Toxicologist
Multimedia Planning & Development
U.S. Environmental Protection Agency
1445 Ross Avenue - Suite 1200
Dallas, TX 75202-2733
214-665-2230
Fax: 214-347-4702
Richard Mattick
Environmental Scientist
Waste, Pesticides and Toxics Division
Waste Management Branch
U.S. Environmental Protection Agency
77 West Jackson Boulevard (DRE-8J)
Chicago, IL 60604
312-886-8093
Fax: 312-353-4788
E-mail: mattick.richard@epamail.epa.gov
Alec McBride
economic Methods and Risk Assessment Division
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
401 M Street, SW (5304)
Washington, DC 20460
703-308-0466
E-mail: mcbride.alexander@epamail.epa.gov
Mary McCarthy-O'Reilly
Science Policy Council Staff
U.S. Environmental Protection Agency
401 M Street, SW (8103)
Washington, DC 20460
202-260-4461
Fax: 202-260-0744
Bruce Means
Special Projects Manager, Response Decisions
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
401 M Street, SW (5204G)
Washington, DC 20460
703-603-8815
B-6
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Ossi Meyn
Environmental Scientist
Health and Environmental Review Division
Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
401 M Street, SW (7403)
Washington, DC 2CH60
202-260-1264
Fax: 202-260-1236
Jayne Michaud
Environmental Scientist
Office of She Remediation and Restoration
Office of Federal Facilities
U.S. Environmental Protection Agency
JFK Federal Building (HBT)
Boston, MA 02203
617-223-5583
Fax: 617-573-9662
E-maihjmichaud.jayne@epamail.epa.gov
Amy Mills
Environmental Scientist
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8623)
Washington, DC 20460
202-260-0569
Fax: 202-260-3803
E-mail: mills.amy@epamail.epa.gov
Bruce Mintz
Biologist
Health and Ecological Criteria Division
^OfRee of Water
U.S. Environmental Protection Agency
401 M Street, SW (4304)
Washington, DC 20460
202-260-9569
Fax: 202-260-1036
E-mail: mintz.bruce@epamail.epa.gov
Edward Ohantan
Technical Advisor
Health and Ecological Criteria Division
Office of Science & Technology/Office of Water
U.S. Environmental Protection Agency
401 M Street, SW (4304)
Washington, DC 20460
202-260-7571
Fax:202-260-1036
Dorothy Fatten
Acting Director
Office of Research and Science Integration
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW(8I04)
Washington, DC 20460
202-260-7669
Fax: 202-260-0106
Andrew Podowski
Toxicologist
Waste Management Division
U.S. Environmental Protection Agency
77 West Jackson Boulevard (SRT-4J)
Chicago, IL 60604
312-886-7573
Fax:312-353-9281
E-mail: podowski.andrew@epamail.epa.gov
Lara Pullen
Risk Assessor
Water Division
U.S. Environmental Protection Agency
77 West Jackson Boulevard (W-l 5-J)
Chicago, IL 60604
312-886-0138
Jon Rauscher
Toxicologist
Super-fund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-L)
Dallas, TX 75202-2733
214-665-6775
Fax: 214-665-6762
B-7
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Larry Reed
Deputy Director
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
401 M Street, SW (5204G)
Washington, DC 20460.
703-603-8960
Fax: 703-603-9146
Joseph C Reinert
Senior Policy Analyst
Office of Policy Development
Office of Policy, Planning, and Evaluation
U.S. Environmental Protection Agency
401 M Street, SW (2123)
Washington, DC 20460
202-260-7557
Fax:202-260-0512
E-mail: reinert.joseph@epamail.epa.gov
Esther Rinde
Senior lexicologist
Health Effects Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
401 M Street, SW (7509Q
Washington, DC 20460
703-305-7492
Fax: 703-305-5453
Zubair Saleem
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-0467
Fax:703-308-0511
Christine Scheltema
Biologist
Health Effects Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
401 M Street, SW (7509Q
Washington, DC 20460
703-308-2201
Sofia Serda
Regional Toxicologist
Hazardous Waste Management Division
Office of Federal Facilities
U.S. Environmental Protection Agency
75 Hawthorne Street (H-9-3)
San Francisco, CA 94105
415-744-2307
Fax: 415-744-1916
E-mail: serda.sofia@epamail.epa.gov
Margaret Stasikowski
Director
Health and Ecological Criteria Division
Office of Science & Technology/Office of Water
U.S. Environmental Protection Agency
401 M Street, SW (4304)
Washington, DC 20460
202-260-5391
Fax:202-260-1036
Ingrid Sunzehauer
Special Assistant
Environmental Fate and Effects Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
401 M Street, SW (7507Q
Washington, DC 20460
703-305-5196
Fax: 703-305-6309
Christina Swartz
Chemist
Risk Characterization and
Analysis Branch
Health Effects Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
401 M Street, SW (7509Q
Washington, DC 20460
703-781-7005
Pat Van Leeuwen
Toxicologist
Super-fund Division
U.S. Environmental Protection Agency
77 West Jackson Boulevard (SRT-4J)
Chicago, IL 60604
312-886-4904
Fax: 312-353-9281
B-8
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Michelle Wei
Environmental Engineer
Iowa Department of Public Health
Lucas State Office Building
Des Moines, IA 50319-0075
515-281^8707
Fax: 515-242-6284
JeffYurk
Toxicologist
Multimedia Planning & Permitting Division
OK/TX RCRA Permits Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-OI445)
Dallas, TX 75202-2733
214-665-8513
Fax: 214-665-6660
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
APPENDIX C
CUMULATIVE RISK IN PROBLEM FORMULATION HANDOUTS
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Cumulative Risk Background Information
The attached material provides an introduction to cumulative risk and problem
formulation. The Science Policy Council is developing a framework for problem
formulation which promotes an op-front discussion between the risk assessor and risk
manager about what kinds of data are available on the factors considered in a risk
assessment and what are the management goals for the risk assessment. The SPC
believes mat we must first identify the range of possible factors mat could be considered
and men document what we actually decide to consider in a risk assessment the
attached materials are intended to help you engage in such a problem formulation
exercise. We hope you will find this material interesting and informative and we invite
your questions and comments.
• The piece entitled, "Cumulative Risk and the Risk Characterization Colloquia"
provides some definitions and an overview of cumulative risk—READ THIS
FIRST.
• The outline "Appendix I Cumulative Risk Factors Matrix" can serve a checklist for
noting in retrospect, what a case study covered and what other areas it should
include if it were done in the future.
• The "Cumulative Risk Assessment Matrix for Triazmes" is an example of mis type
of retrospective analysis developed by members of the SPC for a pesticide review
ofTriazines. On the last page they discuss what they learned from this
examination.
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May 2, 1996
Cumulative Risk and the Risk Characterization Colloquia
Cumulative risk assessment (CSC) is the process for evaluating the aggregate potential for
adverse effects from one or more stressors on a defined population(s). In the risk characterization
coUoquia, CR discussions will focus on the first step— problem formulation. Problem
Formulation is a formal process for generating and evaluating preliminary hypotheses about why
health or ecological effects have occurred, or may occur from environmental stressors,^tfning
management objectives, selecting assessment endpomts, and developing a analytical plan for
MI amiimntMirtd ri«lr • wttm^nt (proKlam fomtitlafirtn ic Ht«^11|frj 'm
below). Problem formulation is not unique to CR, however, his often overlooked.
At the coUoquia, an overview of the cumulative risk assessment project win be presented.
In breakout sessions, participants will be asked to identify facton OB the cumulative risk factors
matrix that could have been addressed for the case study as part of a problem definition exercise.
An example of a completed matrix for Triazines is also attached A fist of possible facton win be
developed and diacusiad m each breakout session on the first day. On the second day, highlights
wifl be discussed on the second day with upper management to klentify the possible benefits of
addressing more factors in the risk assessments and some of the oirrentbarrkn (both regulatory
and procedural).
As a participant, you should review the cumulative risk factors outline (which is attached)
before the breakout sessfba and during the session, ask questiom of the facilitator or case
presenter about these factors. After the breakout session, writedown suggestions or areas where
you fed guidance is needed or where the outline could be expanded Consider how you fed
about the differences between the actual and possible scope of the case example risk assessment
Problem Fonnulatioa Framework
Problem Formulation is a formal process for generating and evahiating preliminary
hypotheses about why health or ecological effects have cccuned, or may occur from
environmental stressors, g management objectives, selecting assessment endpomts, and
developing a analytical plan for condnrrmg an enviromnental risk assesmvmt. The process
consist IT of a ^rtlogw in which the risk assessor «*HJ risk manager define the general parameters of
the assessment: its purpose; die context of the risk, data and resource availability, potential risk
management options, timing, scope, and how risks wul be aggregated. Although some elements
of this process are already used by many program offices, the process k not dearly defined and
the critini d^iiont ibr^it proMf**1 ^*w^**Vm ff nry*y
For CR, problem fbnnulatioo must distinguish between the range of possible assessment
parameters und those that the Agency wffl address and the relative fmplwH on inherent technical
C-2
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or sodoeconomic factors which may affect the risk to certain groups or in certain locations. The
steps in problem formulation are d'«q"«H below.
Identify the purpose. The purpose of the cumulative risk 'f^TfrnCTt is to aggpegtte the
effects of one or more stressors on a defined population. The scope of the assessment will be
influenced by the risk management goals or objectives — which ire based on underlying vahies-r
i.e., the outcomes desired. Goals may Tinge from elimination to partial mitigation of the problem.
In some cases the goals may be compering, so that some negotiation must occur. The risk
assessor should select assessment endpoints and analyses to address these goals/objectives.
Discuss the Questions that should be ^d^TMMd The risk assessor should identify the
context of the risk and develop a Matrix OB outline form) of Cumulative Risk Possibilities. The
risk assessor should identify dtti fMutfH11*1*1*?. their priority, **^ parties (both ***fid* and outside
the Agency) tint should contribute information and participate in the mrttmmt The risk
entifie«riQii and AMa-mappine ayi^mpMnf Therisk
assessor nfuHild d'ffflitf methods, ^*tf. v^ niodfif available to ouantiry ***^ *HHr*ti^tf thffff risks.
The risk manager and the assessor should identify which cc*np*rtments cf the niatrix win be
addressed and document a rationale for those that are exduded. Finalh/, they should develop a
plan to explain how risks wiU be integrated, omibii^wweigtoed for the assessment
Rj«ir ^M^tniffilt AlfP^6*^0118 of Preplan FonmilatMm. Onoe tiie problem formulation
has been completed, the risk assessor can kJentify peer review and outreach rieeds. The risk
manager can estimate time and resource requirements ftndkientiry potential r^
options. At this point, the risk mariagershc^oxisuhwimecctwn^
dtti wiU bf pBfdcd for any cost benefit •««iy««« Twwirtid for the ritV f***tt*ffi*niiftnt decision.
Products from the Problem Fopmilatioii. The products of the problem formulation should
include a set of assessment endpoints tint address ntanagement goals, a matrbx of cumulatrve risk
assessment factory cCTKepttud mcxiels and assuaiptioM
stressor(s) and the assessment endpoints, and t plim for anarysbcf the data.
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***Draft Document for RC CoUoqiiitunDisciuaion only May 6, 1996***
Appendix I. Cff**»n]ativg Risk Factors Matri^fin outline ibrxn)
A- Sources
(What are the Relevant Sources of Stressora?)
1. single source
a. point sources (industrial/commercial discharge, superfund sites)
b. non-point sources (automobiles, agriculture, consumer use
releases)
e. natural sources (flooding, hurricanes, earthquakes, forest fires)
2. Multi-sources (Combinations of those above)
Stressors (What are the Stressors of Concern?)
1. Chemical(s)
a. fiino^
b. Structurally related class of substances
C. StTOCtTOTfllly ^Tirflflt*1^ ""^^nff* ^^h •imtlay TnyiMya^i«ii t hydrologic mft^*^^Btio
harvest)
8. Land-use changes (igrimltnre to MsidVntial, pubHc to private
9. Global dimate change
10. Natural Disasters (Floods, hurricanes, earthquakes)
C-4
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***Draft Document for RC CoIloquiuinDiscuaaion only May 6, 1996***
C Pathways
(Envizomnental Pathways and Routes of Exposure. "What are the Relevant
Exposures?")
1. Pathways (one or more may be involved) .
a. Air
b. Surface Water
c. Groundwater
d, Soil
e. Solid Waste
2. Routes of Human and single species exposures
a. Digestion (both food and water)
b. Dermal (includes absorption and uptake by plants)
c. Tnlmlflritffl Qncludes gaseous exchange
d. Non-dietary ingestion ("hand-to-mouth" behavior)
3. Routes of Exposure within rrrnintnnitiM and ecosystems
a. Bioaccumuj ation
b.
c. Vector transfers
P- Population
( "Who /What/Where is at Risk?")
a, Individual
b. General population distribution or ^fftinmtiffn of central tendency
and ^g^* end
c. Population subgroups
1. Highly exposed subgroup (geographic area, age group,
^DPOQD*
2. Highly sensitive subgroups (a«*^irift'r* or other pre-existing
SJTB)
2. Ecological Entities
a. Groups of individuals
b. Populations
c. Multiple species
d. Habitats/ecosystems
3. T^miiaqfm^i or ClfKwr^p^1'*** Concerns
a. Groundwater aquifers
b. Watersheds (surface water bodies)
c. Airsheds
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***Draft Document for RC ColloquiumDiscusaion only May 6, 1996
d. Regional ecosystems
e. Recreational lands
E . Endpoints
(What are the assessment endpoints?)
1. Human Health (Based on animal studies, morbidity and disease
registries, laboratory and ^nn^i studies, and/or epidemiological studies or
data)
a. Cancer
b.
c. Reproductive dysfunction
d. Developmental
e. Cardio-vascular
£,
g. Others
2. Ecological TSflfrcfr* fThese may be acute,
a. Population or Species
1) Loss of fecundity
2) Reduced rate of growth
3) Acute or Chronic fcmtity
4) Change in biomass
b. Community
DLosa of species diversity
2) Introduction of an CTfftfc species
3) Loes of keystone species
c. Ecosystem
1) Loss of a function (photosynthesis, «Mi»ggal metabolism)
*\ frtfm nf Km
3) LOM of a functional group of organisms (grazers, detritivores,)
4) f^*^«ntt) change (sunlight, temperature change)
5) Loat oflandscape features (migration corridors, home ranges,
Pilflf *^ff^an ^ Timefirames
(What are the Relevant Time Frames: Frequency , Duration, Intensity and Overlap
of Exposure Intervals for Mixtures of Stresaon)?
1. acute
2. subchronic
3. chronic or effects with a long latency period
4. intermittent immigration reserves for replenishing genetic stocks)
C-6
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Draft 5/6/96
Cumulative Risk Assessment Matrix for Triazlnes
(Possible and Actual Factors Considered)
This matrix represents an attempt to the reconstruct the problem formulation
conducted to develop a cumulative risk assessment for three triazine pesticides
(Atrazine.Simazine and Cyanazine). The matrix was developed by the Cumulative Risk
Writing Group, not the Office of Pesticide Programs (OPP), but attempts to capture,
retrospectively, the decision logic OPP applied after it determined that an unreasonable
risk may exist as a consequence of the use of these three chemicals in agricultural and
other settings. (OPP, in fact, did not cany out this formal a problem definition process
when planning this risk assessment). The Writing Group attempted to develop the
matrix in the context of the proposed Cumulative Risk Factors Matrix (see Appendix!).
Atrazine, Simaztne and Cyanazine are herbicides often used in combination with
other pesticides, including with each other or as alternatives to one another, in some
These three herbicides are not the only members of the triazine class. However,
they were analyzed together as a subclass (the cNoro-e-triazines) because they a) are
structurally-related, b) degrade or metabolize to similar degradates/metabolites and, c)
exhibit the same toxicity endpoint of concern (mammary cancer in female Sprague-
Oawley rats) which is believed to develop via the same mode (mechanism) of action.
Cancer is one of the triggers' in the Federal Insecticide, Fungicide and Rodentitide
Act (FIFRA) that allows the Agency to reexamine the eligibility for continued registration
of some or all uses of a pesticide. In the original scoping of the assessment, timing and
resources limited the focus and activity to the human health concern. The Program
also believes that the potential for adverse ecological effects exists, and wilt pursue
that concern in the future.
The factors identified in bold were included in the risk assessment that became
the basis for the Position Document 1-Initiation of Special Review (November 1994).
Dimension A. Sources fWhat are the relevant sources of
etreeeof*?)
1. Single source
C-7
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2. Multiple sources
a. Manufacture
(1) Workers and workplace (covered by OSHA)
(2) Releases from plant (to be covered by TRI)
(3) Waste stream controls (NPDES.RCRA.etc,)
b. M/L/A (MixeriLoador/Applicator; relates to fanner/grower, homeowner.
or commercial applicator)
c. Imports
(1) Residues on imported agricultural products
(2) Transboundary drift
d. Export (largely unregulated)
e. Household use (Le. lawn care)
t Natural sources (flooding, hurricanes, earthquakes) causing
redistxibution'
Dimension B. Strtssors (What are the stressors of concern?)
.1. Chemteal(s)
a. Single chemical
b. Structurally related class of substances
c. Structurally unrelated substances with similar rneehanism of impact and/or
same target organ
d. Mixtures (dissimilar structures/dissimilar mechanisms)
2.
3. l^cwfriolotfoy^^Mologfosl (ranee from nozfaiditv to
4. Nutations! status (diet, fitness, or metabolic state)
5. Eoouft**"* (such as access to hesltli caze)
6. Fsycholofficsl (knowledge o£ living n*flr titir«pfaritt fi§]cs)
. 7. Hflnitu^ Attevafiofi vOZwaxozatuOf oyozoloffic fliooincstiQO
harvest)
8. Land-use changes (agncoltare to rfniidftntial, poblk to private
9. Global «*K«»ata change
10. Natural Disasters (Floods, hurricanes, earthquakes)
Dimension C. Pathways (Environmental Pathways and Routes of
Exposure-NWhat are the relevant Exposures?"
1. Pathwayts) and routes of exposure to humans
a. Manufacture and formulation of products
(1) Pathways
C-8
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(a) Surface water
(b) Air
(c) Solid waste
(d) groundwater
(e) Soil
(f) Indoor
(2) Routes of exposure
(a) Inhalation
(b) Dermal
(c) Ingestion (secondary to initial inhalation or dermal
contact)
D.M/UA
(1) Pathway: Diract contact with applied material
(2) Route of exposure-Dermal
c* Post«appllcation exposure
<1)AQ. reentry
(a) Pathway-Direct contact with applied material
(b) Routes) of exposure-Osrmal, inhalation and indirect
ingestion
(2) Residential (homeowner)
(a) Pathway-Direct contact wrth applied material
(b) Route(f) of exposure-DermaJ, inhalation and indirect
ingestion
(3) Food Onduding water sources)
(a) Pathway(s)-RMidtits In food, surface and
QTourtdwater
(b) Routes) of exposunKdermal and
directTindirect Ingestion
3. • Routes of Bxposnie within cxmiiimnttiee and ecosystems
a. T^i^y^^m^i^^p
c. Vector txaasftn
Dimension D. Poouiation r^VhcVWhatAJVhefe Is at riskm
1. Humans
a. Individual
(1) Manufacture and formulation
(a) Workers
(b) Workers' families
(c) Community members near site
(2) M/UA
C-9
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(a) Workers-categorized by age.sex.reproductive
status
(b) Workers' families
(3) Post-application Exposure
(a) Ag. Reentry
(b) Residential
(c) Food (Including water)
b. General population distribution and estimation of
central tendency and high end
(1) Manufacture and formulation
(a) Workers
(b) Workers'families
(c) Community members near sit*
(2)M/L/A
(a) Workers-categorized by age,sex,reproductive
status
(b) Workers'families
(3) Post-application Exposure
(a) Ag. Reentry
(b) Residential
(c) Food (Including water>-exposure assessment
assumed average food consumption/residue
values, but drinking water at the MCL (I.e.
high end)
c. Population subgroups
(1) Highly exposed subgroup (e.0. occupational,
geographic)
(a) Manufacture and formulation
(i) Workers
Oi) Workers'families
(ill) Community members near site
(bJftVL/A
(1) Workers-categorized by
agelsextreproductive status
(ii) Workers'families
(e) Post-application Exposure
(i)Ag. Reentry
(ii) Residential
(10) Food (including water}-
assessment assumed average food
consumption/residue values, but drinking
c-io
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water at the MCL(i.e.high end)
(2) Highly sensitive subgroup (no consensus as to whether infants
and children should be considered 'highly sensitive"; nonetheless, the dietary
risk assessment evaluated exposure/risk to 22 subgroups as well as the general
population)
(3) GeographicaHHigher dietary risk estimated in areas with high
agricultural use, e.g. Midwest com bett)
2. Ecological Entities-{Future)
a. Groups of individuals
b. Populstions
c. Multiple species
dL T
3. Landscape OF Geographic
a. Qroundwater aquifers
b. Watersheds (surface water bodies)
c. Airsheds
Dimension E. Endpolnts (What are the assessment endpoUits?)
1. Human Health
a. Cancer (this endpotnt •drove" the risk assessment)
b. Cardlotoxldty (Questions resolved for atrazJne;endpoint considered
•covered" by cancer risk assessment)
c. Reproductive/developmental toxtetty
e. Neurotoxidty
f. Immunotoxkaty
g. Other: systemic toxidty
2. "B
a. Population or Species
1) Loss of fecundity
2) Reduced rate of growth
3) Acute or Chronk toxicity
4) Chance in biomass
^f ^^^^^^«^^ ^^" « •• ^^*^^~^
b. uommunity
1) Loss of species diversity
2) Introduction of an exotic species
3) Loss of keystone species
c. Ecosystem
C-ll
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1) Loss of a function (photosynthesis, mineral metabolism)
2) Loss of habitat structure
3) Loss of a functional group of organisms (grazers, detritivores,)
4) Climate change (sunlight, temperature change)
5) Loss of landscape features (migration corridors, home ranges,
Dimension F. Tlmeframes ("What art the relevant timeframes" Frequency,
Duration, Intensity and Overlap of Exposure Intervals for Mixtures of Stressors?"}
1. Acute
2. Subchronic (Including Intermittent)
3. Chronic or effects with long latency period (Including
intermittent)
Lessons Learned
- The most .obvious lesson teamed is that the exercise of problem formulation
should be carried before the risk assessment is started.
Also, ft was very dear, even during this vary cursory attempt to reconstruct the
decision logic, that additional sources of exposure could, and, perhaps, should have
been- considered in developing the risk assessment Generally, however, experience
tells us that occupational exposure related to mbdnoy»c«dtno/applyingpe$ticjde
products presents the greatest potential for risk. In this case, the risk assessment
covers the domain of more than one Program office (OPP and OW), showing that
inadvertent contamination of drinking water supplies may be a major risk factor, at least
for a significant subset of the U.S. population. This circumstance offers the possibility of
identifying risk reduction measures under more than one legislative mandate.
Lastiy, tha existing risk assessment is limited to the evaluation of human health
concerns. Not completely transparent in the exercise Described above is the decision
that time, resources and tha existing data ware not available to go forward wrth an
assessment of ecological effects at tha same time as tha assessment of human health
risk A good problem formulation would include a systematic evaluation of all factors,
and a full documentation of tha decisions to indude/exduda certain of those factors.
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Cumulative Risk Project
Sponsored by the Science Policy
Council
Rationale for Projec
L Consider Total Environmental Risks
2. Develop CR Concept Beyond
"Multiple-Multiples"
3. Improve Risk Assessor/Manager
Communication
4. Explain Agency Role to Public
- Define risks within EPA authority
— Discuss other risk management options
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Definition of Cumulative Risk
"Risks from one or more stressors
considered in aggregate"
Each Assessment is case-specific
• Who is affected or stressed?
• What are the stressors?
• What are the sources?
• What are the pathways?
• What is the time frame for the risk?
• What are the assessment endpoints?
Purpose and Scope of
i Address aspects of CR within
EPA regulations
! Establish a framework to:
• Define the problem formally
-Set the context of the risk
-Identify participants, time, and resource needs
-Define rationale for aggregating risks
-Document what will/will not be addressed
C-14
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Project Scope (cont
Coordinate with Risk Charactei
Implementation Steps
- Case Studies to define CR practice
- Workshops to define CR potential uses and
Research Needs
- Guidance to implement CR process
-Develop implementation policy
Cumulative Risk Frame
1995
C-15
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Problem Formulation
• What can and will we
address?
• Risk Assessor-Risk
Manager Dialog
• Preparation for a risk
assessment
Problem Formulation
Risk Assessor/Manager Define
• Management Goals and Values
• ID context of the Risk
• Discuss questions to be answered
• Estimate resource, data and time
requirements
• Identity participants (Agency and Beyond)
C-16
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Cumulative Risk Matrix
Cumulative Risk Matrix
Effects
Sources
Population
Pathways
C-17
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Objectives of Problem
Formulation
o Achieve desired management outcome
9 Match assessment endpoints to goal
o Document Basis for Risk
Characterization
Limitations in Current P
Scope often Confined by Stati
Generally Assumes Risks are Additive
Unregulated Source contribution often
overlooked
Cost-data intensive; may be expensive
• Collaboration and problem definition can
reduce costs significantly
C-18
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What does a Manager want to
know before you start?
• Scope of the Risk
• What data are needed?
• What data are
available?
• Who can help?
• Schedule-Cost
• Knowledge gaps
• Public concerns
Cumulative Risk Objective
the Colloquium
• Apply Problem Formulation to the Case
Studies
• Brainstorm a list of Possible Risk Factors
• Discuss the implications assessors
• Identity elements of CR from the Case
Studies
C-19
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
APPENDIX D
CASE PRESENTERS, CHAIRS, AND FACILITATORS
-------
&EPA
United States
Environmental Protection Agency
Science Policy Council
Risk Characterization Colloquium
Series Cl: OSWER and Regions
Holiday Inn Bethesda
Bethesda, MD
June 6-7, 1996
Colloquium Chain Penelope Fenner-Crisp
Plenary Session I Presenters:
Penelope Fenner-Crisp
Margaret Stasikowski
Jack Fow/e
Ed Bender
Ed Ohantan
Case Study A: Lavaca Bay (OERR and Region 6)
Session Chair: Dave Bennett
Facilitator: Ruth' Bley/er
Case Presenters: Janine Oman and Jon Rauscher
Case Study B: Midlothian (Region 6)
Session Chair: Gerald Comey
Facilitator: Ed Ohanian
Case Presenter: Jeffrey Yurk
Case Study C: RCRA Biocrude (OSW)
Session Chair: Donald Barnes
Facilitator: Jack Fow/e
Case Presenters: Dave Cozz/e and Becicy Daiss
Case Study D: Waquort Bay Watershed (OW and Region I)
Session Chair: Margaret Sfasikowslci
Facilitator: Paf Cirone
Case Presenter: Suzanne Morcy
i Printed on Recycled Paper
D-l
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
DRAFT
^PRELIMINARY SUMMARY OF THE U.S. EPA
COLLOQUIUM/ROUNDTABLE ON RISK CHARACTERIZATION
MEETING 2, SERIES C: OSWER AND REGIONS
(C-2 )
Prepared for:
U.S. Environmental Protection Agency
Science Policy Council
401 M Street SW.
Washington, DC 20460
Contract No. 68-D5-0028
Work Assignment No. 95-06
Prepared by:
Eastern Research Group, Inc.
110 Hanwell Avenue
Lexington, MA 02173-3198
December 31. 1996
-------
DRAFT—DO NOT COPY, DISTRIBUTE. OR QUOTE.
NOTICE
Mention of trade names or commercial products does not constitute endorsement or recommendation
for use. Statements are the individual views of each meeting participant; the statements in this preliminary
summary do not represent analyses or positions of the Science Policy Council or the U.S. Environmental
Protection Agency (EPA).
This preliminary summary was prepared by Eastern Research Group, Inc. (ERG), an EPA contractor,
as a general record of discussions held during the Risk Characterization Colloquium/Roundtable, Meeting 2
of Series C: OSWER and Regions. As requested by EPA, this preliminary summary captures the main
points and highlights of the meeting. It is not a complete record of all details discussed, nor does it embellish,
interpret, or enlarge upon matters that were incomplete or unclear.
Several individuals from EPA and the Science Advisory Board collaborated to organize this
.colloquium, including:
Dorothy Patton
Margaret Stasikowski
Donald Barnes
Peter Preuss
Jack Fowle
Ed Bender
Ed Ohanian
Kerry Dearfield
Mary McCarthy-O'Reilly
Ruth Bleyler
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
CONTENTS
Page
PREFACE v
SECTION ONE—BACKGROUND 1-1
EPA's Risk Characterization Policy 1-1
Implementation of EPA's 1995 Risk Characterization Policy 1-2
Meetings Held to Date 1-6
The August 1996 Series C Colloquiura/Roundtable 1-9
SECTION TWO—OPENING PLENARY SESSION 2-1
Welcome to Region 6 2-1
Welcome, Opening Remarks, and Background 2-2
Regional Focus for Risk Characterization 2-7
Planning and Scoping for Cumulative Risk Assessment and Characterization 2-7
Case Study Overviews 2-11
SECTION THREE—BREAKOUT SESSION 3-1
Lavaca Bay 3-1
Midlothian 3-5
Biocrude 3-6
Waquoit Bay 3-9
SECTION FOUR—CLOSING PLENARY SESSION 4-1
Highlights From Breakout Session 4-1
Risk Managers' Roundtable Discussion 4-5
Next Steps 4-11
Adjournment 4-12
APPENDIX A—AGENDA A-l
APPENDIX B—ATTENDEE REGISTRATION LIST B-l
in
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APPENDIX C—CUMULATIVE RISK ASSESSMENT
PLANNING AND SCOPING HANDOUTS C-l
APPENDIX D—CASE PRESENTERS, CHAIRS, AND FACILITATORS D-l
APPENDIX E—CASE STUDY HANDOUTS E-l
Lavaca Bay ., E-l
Midlothian E-39
Biocrude E-63
Waquoit Bay E-175
APPENDIX F—PRELIMINARY IMPLEMENTATION STATEMENTS F-l
Region 6 Implementation Statement F-l
Office of Solid Waste Implementation Statement : F-33
Superfund Assessment Process F-57
APPENDIX G—RISK CHARACTERIZATION POLICY
BACKGROUND MATERIALS G-l
IV
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PREFACE
On August 1 and 2,1996, EPA's Science Policy Council held the fifth in a series of
internal colloquia/roundtables on risk characterization. This preliminary summary presents
highlights from the meeting, focusing on issues raised, but generally and deliberately not
resolved, in meeting discussions. Like the colloquium/roundtable, the summary is intended to
stimulate discussion and generate ideas. It is presented as a vehicle for a continuing Agency
dialogue on risk characterization, not as a statement of positions or a source of answers.
The colloquium/roundtable series continues and expands the discussion that began with
the Administrator's March 21,1995 memorandum on risk characterization. That memorandum
established core principles for characterizing risk and inaugurated a two-part program to
implement those principles across EPA. For over a year, a Science Policy Council inter-office
risk characterization "Implementation Team" has been working to convert the core principles into
useful guidance for Agency assessors and managers. This is conceived as a "bottom-up" exercise,
drawing on the variety of experience among scientists and managers in different EPA program
offices, regional offices, and laboratories. The risk characterization policy and implementation
program are consistent with a Science Policy Council goal of stimulating broad EPA participation
in important science policy initiatives.
In August 1995, the Implementation Team completed the first stage of the program by
preparing preliminary office-/region-specific statements of principles and procedures for guiding
risk characterization implementation efforts in their respective offices/regions ("Preliminary
Implementation Statements"). The August statements are preliminary because the drafts for
each office/region are being tested and evaluated by both risk assessors and risk managers in the
colloquium/roundtable series. The drafts for many offices/regions will be revised before we are
confident that we have workable statements that are consistent with both the principles set forth
in the Administrator's memorandum and the needs of different EPA offices and programs. The
colloquium series is designed to encourage this kind of testing throughout the Agency.
In September 1995, EPA held the first in the series of colloquia on risk characterization.
issues. It featured risk characterization "cases" from the Office of Air and Radiation (OAR) and
the Office of Research and Development (ORD). The second colloquium featured cases from
the Office of Water (OW) and two offices within the Office of Prevention, Pesticides and Toxic
Substances (OPPTS)—the Office of Pesticides Programs (OPP) and the Office of Pollution
Prevention and Toxics (OPPT). The third meeting was a colloquium and roundtable in which
risk assessors and risk managers jointly discussed revised versions of the OW and OPPTS cases,
focusing especially on risk management issues affecting risk characterization.
The fourth meeting was held in June 1996 and featured risk characterization cases from
the Office of Solid Waste and Emergency Response (OSWER) and EPA regions. The fifth
meeting, the colloquium and roundtable that is the subject of this summary, provided a forum for
risk assessors and risk managers to engage in a dialogue about revised versions of the OSWER
and regional case studies. All five meetings focused on generic risk characterization issues, with
the particular cases presented only as vehicles for discussing these issues; interested scientists and
managers from many different offices (not just those producing the case studies) participated in
the discussions. Meeting comments and recommendations will be used to influence future
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development of office-/region-specific risk characterization statements. Any Agency review of the
cases themselves will take place through customary procedures.
As a review of issues raised in the August 1996 colloquium/roundtable, with more
meetings planned to complete the series, this preliminary summary is a work in process. The
Science Policy Council staff will prepare a short summary for each meeting to mark issues raised
and progress made. Each meeting summary will begin with a background section that briefly
explains the history of risk characterization policies and their implementation within EPA.
Except for minor adjustments to reflect progress made in the implementation program, the same
background section will appear in each meeting summary. The remainder of each meeting
summary will consist of ideas discussed in the meeting.
At the conclusion of the colloquium/roundtable series, the Science Policy Council will
collect relevant information and materials into a final report. At that time, the Council will also
work with Agency program offices and regions to plan and schedule external peer review
activities.
Dorothy E. Patton, Ph.D.
Acting Director, Office of Research and Science Integration
Executive Director, Science Policy Council
VI
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SECTION ONE
BACKGROUND
EPA'S RISK CHARACTERIZATION POLICY
NOTE: Background material for the report from each colloquium/roundtable in the series is
essentially identical so that the meeting audiences will have the same information.
The cases and outcomes vary for the different colloquia/roundtables.
At EPA, analyses of scientific information on risks to human health and the
environment—risk assessments—are among the most important factors decision-makers consider
when making policy decisions. Recognizing the critical role of risk assessments, EPA has long
taken steps to ensure that Agency risk assessments are sound and credible. For example, EPA
has developed a variety of human health risk assessment guidelines over the years, many of which
specify methods and procedures for conducting the first three steps in the risk assessment process
(hazard identification, dose-response assessment, exposure assessment).
In the early 1990s, several observations prompted EPA to focus more attention on the
fourth, integrative step (risk characterization) in the risk assessment process. Among these were
observations that EPA risk assessors and risk managers frequently communicated the results of
EPA risk assessments without indicating the range of information considered in developing the
assessments and that they used different descriptors of risk in different risk assessments. In 1992,
EPA issued a policy memorandum and guidance package on risk characterization to encourage
fuller risk characterizations, to promote greater consistency and comparability among EPA risk
characterizations, and to clarify the role of professional judgment in characterizing risk. The
policy called on risk assessors and risk managers to communicate the scientific basis of risk
conclusions (i.e., to provide a combined and integrated view of the evidence with a full and open
discussion of the strengths, limitations, and uncertainties), to use standard descriptors of risk, and
to use multiple risk descriptors—all with the aim of generating more complete, higher quality,
and more consistent characterizations of risk in EPA risk assessments.
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Although EPA's 1992 risk characterization policy sparked considerable discussion and
progress, implementation was incomplete. In its 1994 report, Science and Judgment in Risk
Assessment, the National Research Council concluded that "EPA's overall approach to assessing
risks is fundamentally sound despite often-heard criticisms, but the Agency must more clearly
establish the scientific and policy basis for risk estimates and better describe the uncertainties in
its estimates of risk." To ensure communication of the scientific basis of risk conclusions and to
promote greater transparency, clarity, consistency, and reasonableness in risk assessments across
Agency programs, EPA Administrator Carol Browner issued a new risk characterization policy
and guidance on March 21,1995. In this policy, Administrator Browner refines and reaffirms the
principles and guidance found in the 1992 policy and outlines a process for implementing them.
IMPLEMENTATION OF EPA'S 1995 RISK CHARACTERIZATION POLICY
In her March 1995 risk characterization policy statement, Administrator Browner charges
the Science Policy Council (SPC) with organizing Agency-wide implementation activities to
promote consistent interpretation of the policy, to assess the progress of implementation, and to
recommend revisions to the policy and guidance as necessary. In addition, she calls for the
establishment of an Implementation Team (composed of representatives from EPA
Headquarters, program offices, and regions) to coordinate development of office-/region-specific
policies and procedures consistent with the policy and guidance.
In April 1995, the SPC established an Implementation Team, which has begun the task of
converting the core principles embodied in Administrator Browner's risk characterization policy
into office-specific guidelines for Agency risk assessors and managers. In June 1995, members of
the Implementation Team prepared first drafts of office-specific implementation statements of
principles and procedures for risk characterization in their offices or regions. In August 1995,
after considerable discussion, they produced preliminary implementation statements for further
discussion and testing.
To ensure the integrity and practicality of the implementation statements, the SPC and
Implementation Team have developed a process for testing, evaluating, and revising the
statements in the context of real-world applications. The process consists of three parallel series
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of meetings at which risk assessors and risk managers will discuss the application of the
implementation statements to specific case studies to determine whether the statements are:
• Specific enough to guide development of good risk characterizations.
• Flexible enough to allow for differences in detail.
" Complete enough to allow objective judgment of compliance.
• Organized in a way that is useful to the office or region.
The three series of meetings will focus on OAR and ORD implementation statements and
case studies, OW and OPPTS implementation statements and case studies, and Office of Solid
Waste and Emergency Response (OSWER) and regional implementation statements and case
studies, respectively. As initially envisioned, each series would include three meetings1 (see
figures 1 and 2):
A colloquium for risk assessors at. which office or region personnel will present
case studies and discuss them with attendees to identify, categorize, and suggest
solutions for issues encountered in applying the implementation statements.
After the colloquium, the case study authors will complete risk characterizations
for their case studies.
A colloquiumlroundtable for risk assessors and risk managers at which the case
study authors will discuss how they addressed the issues discussed in the previous
colloquium in their risk characterizations and attendees will discuss issues that
might arise from a risk management perspective. After this meeting, the authors
will re-examine their risk characterizations based on the attendees' comments.
A roundtable for risk managers and decision-makers at which the case study
authors will present their revised risk characterizations and the attendees will
explore risk management issues in greater detail. After the roundtable, the
authors will complete their risk characterizations for peer review and
Implementation Team members will reconsider and, as appropriate, revise their
office-specific implementation statements.
on substantial progress made during the early meetings, as well as feedback from
meeting participants, the SPC subsequently decided to eliminate the third meeting in each
meeting series. Thus, an "all hands" plenary session will follow the colloquia/roundtables rather
than the roundtables described here.
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Risk Characterization
Colloquia and Roundtables
Series A
Series B
Series C
OAR/ORD
colloquium
colloquium/
roundtable J'»
OW/OPPTS
(colloquium)
colloquium/
roundtable
OSWEffiREGIONS
colloquium,
colloquium/
roundtable
iroundtabie)
(roundtable;
roundtable.
PLENARY SESSION
Figure 1. Overall structure of EPA's planned implementation meetings.
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Genera/ plan for each series
select cases
colloquium/
roundtabie
"homework"
"homework"
Peer Review
Plenary
1. Present case.
2. identify characterization issues.
3. Receive recommendations.
1. Resolve issues.
2. Prepare risk characterization.
3. Identify expected management issues.
1. Present characterization.
2..Get feedback,
3. Present management issues.
1. Resolve management issues.
2. Modify the risk characterization
to accommodate colloquium
feedback and management issues.
1. Present revised characterization.
focussing on management issues.
2. Get feedback.
1. Complete risk characterization
for peer review.
2. Rework the Office/Region-specifTc
Statement.
Products
1. Model risk characterization.
2. Revised Office/Region-Specific
Statement.
Figure 2. General plan for each implementation meeting series.
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These series of meetings will culminate with a wrap-up session to consider issues raised,
lessons learned, and next steps. The SPC and Implementation Team constructed this meeting
plan not only to ensure production of credible, useful office-specific implementation statements
and model risk characterizations, but also to achieve the broader implementation objectives of:
Tangibly demonstrating EPA's commitment to risk characterization by converting
the risk characterization principles in the 1995 policy into practice in all parts of
EPA.
Providing a multi-office forum for discussion and debate of risk characterization
issues.
Increasing the credibility of Agency risk characterizations.
Developing measurable criteria to help risk assessors and risk managers
understand what is expected of them and to help others measure the success of
EPA risk characterization efforts.
MEETINGS HELD TO DATE
On September 7 and 8,1995, the SPC held the Series A Colloquium on Risk
Characterization ("Meeting Al") in Washington, DC. As the first meeting conducted under the
plan described above, it represented EPA's first opportunity to assert its commitment to risk
characterization and describe the implementation plan to a broad EPA audience of risk assessors
and other interested attendees. To that end, EPA Deputy Administrator Fred Hansen opened
the meeting with introductory remarks on the importance of-risk characterization and the
attention being accorded this topic at the highest levels of EPA. Members of the
Implementation Team then provided background information and explained the team's
implementation plans. The remainder of the colloquium focused on the preliminary OAR and
ORD implementation statements, which attendees discussed in the context of four case studies
developed and presented by individuals from these offices. The implementation statements and
case studies sparked lively conversations about risk characterization issues as well as suggestions
for improving future colloquia.
The Series B Colloquium on Risk Characterization ("Meeting Bl") held on December 14
and 15,1995, in Washington, DC, was the second meeting conducted under the SPC's risk
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characterization meeting plan. Consistent with its commitment to listen to and adopt useful
ideas from all parts and all levels of the Agency, the SPC arranged for many of the suggestions
from the first colloquium to be implemented in this colloquium. For example, the SPC:
Worked with program offices to reformat the preliminary implementation
statements under discussion at the meeting.
Met with breakout session chairs, presenters, and facilitators to plan the
colloquium and resolve any remaining issues.
Worked with case study presenters to develop a consistent format for the case
study handouts (i.e., one that begins with a section on risk characterization issues
followed by a summary of the case).
Met with the colloquium chair to design an "effective" closing plenary session.
Asked case study presenters to give fictional names to the compounds addressed
in their cases to encourage free discussion of risk characterization issues.
Distributed the preliminary implementation statements and case study handouts
prior to the colloquium.
Assigned facilitators to breakout sessions to "stimulate" discussions.
Asked the case study presenters to give a brief overview of their cases during the
colloquium's opening plenary session to familiarize the attendees with the case
studies/issues.
Distributed a suggested format for reports from breakout sessions to ensure
consistency.
During the colloquium, many attendees noted that their suggestions had been
implemented and commented that the changes had enhanced the running and effectiveness of
the colloquium. Indeed, the meeting provided an excellent opportunity to explore in depth the
practical issues involved in using the preliminary implementation statements prepared by OW
and two OPPTS offices (OPP and OPPT).
The Series B Risk Characterization Colloquium and Roundtable ("Meeting B2") held on
May 30 and 31,19%, in Bethesda, MD, was the third meeting conducted under the SPC's overall
risk characterization meeting plan—and the second meeting conducted under Series B. As such,
it featured a colloquium to allow risk assessors and risk managers to jointly discuss risk
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characterization issues important to them in the context of case studies (revised versions of those
presented in Meeting Bl) and a roundtable to provide a forum for open discussion of risk
management issues with risk managers at multiple levels within the EPA organization.
In keeping with the SPC's "work in progress" approach to the risk characterization meeting
series, the B2 colloquium/roundtable built on experiences and suggestions from previous
meetings. For example, the format for the meeting grew out of suggestions that the risk
assessor/risk manager relationship be thought of as a bridge that facilitates and enhances the
work of both parties rather than being constrained by a steel dividing wall. Similarly, the
meeting format was also shaped by two other recurring themes heard in previous meetings: the
utility of conducting a problem formulation step in human health and ecological risk assessments
alike, and the need to address concerns about cumulative risk. To fold these issues into this and
future risk characterization meetings, the SPC added a presentation on how to begin addressing
cumulative risk in the problem formulation stage of risk assessment. As hoped, the meeting
brought together disparate groups and perspectives, providing a forum for collaboration,
agreement, and disagreement.
The Series C Colloquium on Risk Characterization ("Meeting Cl") held on June 6 and 7,
1996, in Bethesda, MD, was the fourth meeting conducted under the SPC's risk characterization
meeting plan. As such, it incorporated all the features described above to provide the most
productive circumstances possible for discussing case studies from OSWER and EPA regions:
Lavaca Bay, a preliminary assessment conducted by Region 6 to investigate the
ALCOA (Point Comfort)/Lavaca Bay Superfund Site and develop a
comprehensive assessment plan under the Superfund Amendments and
Reauthorization Act of 1986 (SARA),
Midlothian, a cumulative risk assessment conducted by Region 6 to support the
State of Texas's consideration of an application by a cement kiln to burn
hazardous waste as fuel.
Biocrude, a multimedia baseline risk assessment conducted by the Office of Solid
Waste (OSW) to determine whether biocrude should be listed as a hazardous
substance under the Resource Conservation and Recovery Act (RCRA).
Waquoit Bay Watershed, an ecological risk assessment initiated by Region 1 and
cosponsored by OW and ORD to demonstrate the value of ecological risk
assessment for community-based efforts to protect ecological resources.
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The meeting proved to be fruitful in identifying issues involved in using the preliminary
implementation statements prepared by EPA offices and regions.
THE AUGUST 1996 SERIES C2 COLLOQUIUM/ROUNDTABLE
The Series C Risk Characterization Colloquium and Roundtable ("Meeting C2") held on
August 1 and 2,1996, in Dallas, TX, provided a forum for risk assessors and risk managers to
jointly discuss risk characterization issues in the context of the case studies listed above (Day 1)
and a roundtable to provide a forum for open discussion (Day 2). To provide context and
stimulate discussion, Deputy Regional Administrator Allyn Davis (Region 6 Compliance and
Enforcement Division) offered his perspective on the importance of risk characterization,
members of the SPC presented background information on risk characterization at EPA,
Region 6 Toxicologjst Gerald Carney provided additional regional perspective on risk
characterization, an SPC staffer gave an overview of issues related to planning and scoping for
cumulative risk assessment and characterization, and the case study presenters offered a brief
overview of their cases (see agenda in appendix A and summary in section 2).
After meeting in an opening plenary session to hear this background information,
colloquium attendees participated in breakout group discussions of the case studies. Following
the breakout sessions, the attendees reconvened in a plenary session to discuss the major issues
they had identified, hear comments from risk managers, and engage in a dialogue with the risk
managers. As at previous meetings, opinions were diverse, reflecting the diverse backgrounds
and perspectives of the attendees (see attendee registration list in appendix B),
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SECTION TWO
OPENING PLENARY SESSION
Penelope Fenner-Crisp, Deputy Director of OPP and a member of the SPC, chaired the
Colloquium and Roundtable on Risk Characterization. She began the meeting by introducing
Allyn M. Davis, Deputy Regional Administrator (Region 6 Compliance and Enforcement
Division), who welcomed the attendees to Dallas and offered his perspective on the importance
of risk characterization.
WELCOME TO REGION 6
Deputy Regional Administrator Allyn Davis began his remarks by noting that risk
assessors have one of the hardest jobs in EPA because how we describe risk determines the
success or failure of a program—and the first hurdle lies in communicating risk to managers,
some of whom want simple answers even when the issues are complex. Citing the "MEGO" ("My
Eyes Glaze Over") phenomenon, Allyn Davis related an anecdote in which a manager being
briefed on an issue interrupted the presentation to say "I just want to know the time, not how to
build a clock." Risk assessors, he said, are put in the difficult position of being asked to present
risk information simply and concisely when simplicity can be inaccurate or misleading.
Nevertheless, the value of rigorous risk characterization is increasingly being recognized. Allyn
Davis cited examples (including the Midlothian case discussed in more depth later in the meeting
and one involving an ozone standard) in which public involvement or reaction has spurred states
and regions to pay closer attention to the types of issues being discussed in this meeting series.
Allyn Davis concluded his remarks by stating that, although challenging, characterizing risk
well is critical to sound decision-making, communicating risk and management decisions to the
public, and maintaining EPA's constituency. He urged the attendees to persevere in their efforts
to advance risk characterization at the Agency.
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WELCOME, OPENING REMARKS, AND BACKGROUND
After Allyn Davis's remarks, Penelope Fenner-Crisp also welcomed the attendees. She
and other members of the SPC went on to provide additional introductory remarks and
background information on risk characterization. They noted that the transparency, clarity,
consistency, and reasonableness (TCCR) called for in Administrator Browner's risk
characterization policy have become the watchwords of risk characterization. EPA is moving
toward those goals, but has not yet identified a "perfect" risk characterization. Nor has anyone
else. Some attendees of previous meetings suggested that risk characterizations are necessarily
so diverse (resulting, as they do, from different levels of risk assessment and different
information needs) that no single risk characterization can serve as a model.
Indeed, the concept of risk characterization is changing. Attendees of previous risk
characterization meetings described risk characterization as an abstracting process yielding a
variety of risk characterization products for different audiences (see figure 3). Moreover, recent
National Research Council and other publications are beginning to describe the risk
characterization process even more broadly—to include early stakeholder involvement and broad-
based deliberation of value judgments. To date, these factors and processes have been
considered separate inputs into risk management decisions (see figure 4), with risk assessment
and risk characterization being the most clearly explicated of the inputs.
Some attendees of previous risk characterization meetings felt that the preliminary risk
characterization implementation statements drafted during the past year are too detailed. One
EPA group put together a series of seven steps to better risk characterization (see figure 5). The
speakers encouraged the attendees to discuss these suggested steps during the breakout group
discussions. They also encouraged the attendees to speak freely and openly on other issues, too,
stating that the meeting is intended to provide a forum for frank discussion. The goal is to
identify risk management issues, strategies for dealing with risk management issues, the role of
problem formulation in addressing these issues, and ideas for next steps (see figure 6).
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Risk
Assessment
(HI, DR, Exp)
Peer Reviewers
Risk Assessors
Risk Characterization
Abstracting Process
Peer Reviewers
Risk Assessors
Smrimary (ies)
Peer Reviewers
Risk Managers
Communication
Pieces
Peer Reviewers
Public
Figure 3. Concept of risk charactepiration offered by attendees of the first colloquium.
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PROBLEM
Economic
Characterization
K I
Risk
Assessment
Risk
Characterization
\
Values
Characterization
Decision
Legal ft Statutory
Characterization
Social Factors
Characterization
Political Factors
Characterization
Figure 4. Inputs into the decision-making process,
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Risk Characterization Statement
Seven Steps to Better Risk Characterizations
1. Indicate the Scope of the Assessment (Match Level of
Effort to the Scope.)
2. Summarize the Major Risk Conclusions and the Level of
"Comfort" the Risk Manager May Place in the Conclusions
3. Identify Key Issues. (A Key Issue is Critical to Properly
Evaluate the Conclusions.)
4. Clearly Describe the Methods Used. (Give Qualitative
Narration to Quantitative Results.)
5. Summarize the Overall Strengths and Major Uncertainties
6. Put this Assessment into a Context with Other Similar
Risks
7. Identify Other Important Information About the
Assessment
'*
From the OPPT Risk Characterization Training Course
Figure 5. Seven steps to better risk characterization.
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Possible Measures of Success
1. Issues/points raised in the case studies are stratified into:
a. Things the risk managers can live with
b. Things that prove sticky but can be fixed
c. Things the risk managers can't live with
2. Participants come to realize that Risk Characterization provides flexibility
allowing EPA to flex when it needs to flex and it is spine stiffening too, providing
EPA with the ability to stand ground in the face of uncertainty (e.g., we're making
choices informed by but not driven by science). Look for specifics from the case
studies and/or hypothetical examples (e.g., the scenarios from the proposed points
to consider paper)
a. How to stand up
b. How to articulate
c. What is the strategy(ies) for dealing with risk assessment results that
prove difficult to managers
3. Risk managers indicate whether and how problem formulation and
consideration of cumulative risk helps them focus on what they want and need.
a. They indicate whether the problem formulation matrix developed for
cumulative risk is helpful for risk characterization
b. They react to the realzation that office specific assessments only
cover a piece of the cumulative risk pie.
4. Next steps are identified
a. What did we learn from the case studies?
b. How can we apply the lessons learned?
c. What's left undone?
d. What do we need to do?
Figure 6. Desired outcomes of the C2 risk characterization meeting.
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REGIONAL FOCUS FOR RISK CHARACTERIZATION
Following these introductory presentations, Region 6 lexicologist Gerald Carney provided
a regional perspective on risk characterization. Noting that nearly all regional decisions are
based on some type of risk assessment, he said that he views development of the Region 6 risk
characterization implementation statement as an opportunity to sort out the various types of risk
assessments conducted in the region. Furthermore, he stated that he views this meeting as an
opportunity to discuss the utility and implications of the preliminary implementation statement
for individual regional programs—which, after all, vary widely in how they are involved in risk
assessment and risk characterization. Gerald Carney encouraged the attendees to raise questions
about and discuss regional program-specific applications of the risk characterization principles
laid out in Region 6's preliminary implementation statement.
PLANNING AND SCOPING FOR
CUMULATIVE RISK ASSESSMENT AND CHARACTERIZATION
In their introductory remarks, several speakers alluded to the increased attention that
problem formulation is receiving as a means of planning and scoping out risk assessments and
risk characterizations. Ed Bender described EPA's current work on the subject and invited the
attendees to contribute ideas and suggestions during and after the meeting.
Ed Bender began his presentation by explaining that the Cumulative Risk Project arose
from a variety of trends and forces, such as management interest in broadening risk assessment
to encompass public concerns about total risk. He said that project participants began by
drafting a broad definition of cumulative risk: risks from one or more stressors considered in
aggregate. In developing this definition, project participants noted that addressing cumulative
risk involves asking questions about various "risk dimensions"—who is affected/stressed, what are
the stressors, what are the sources, what are the pathways, what is the time frame for the risk,
and what are appropriate assessment endpoints.
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Cumulative Risk Project participants have drafted a preliminary framework for the risk
assessment/risk management decision process that proposes an interactive, iterative process for
addressing cumulative risk (see figure 7). This framework begins with problem formulation,
when risk assessors and risk managers engage in a dialogue to develop hypotheses about the
relationship between stressors and endpoints, decide what can and will be addressed, and define
the scope of the risk assessment. Even at this early stage, economic, political science, and social
analysis information and stakeholder input may inform risk assessors' and risk managers' work.
The next two phases are risk assessment and risk characterization. Ed Bender focused his
presentation on problem formulation (planning and scoping) as the first step in ensuring the
integrity of the risk characterization ultimately produced.
According to the proposed risk assessment/management decision process framework,
problem formulation involves an "Assessor/Manager Dialogue" consisting of multiple interactions
in which risk assessors and risk managers each provide information and ask questions needed to
formulate the purpose and scope of the assessment. Risk assessors provide background
information and ask about possible risk management options, while risk managers ask for
contextual information about the risk and identify management goals and values (see figure 8).
Other participants, including stakeholders and economists, are also identified and may provide
additional input.
To facilitate cumulative risk problem formulation, Cumulative Risk Project participants
have drafted a cumulative risk matrix that can be used to identify all possible assessment
endpoints; risk assessors and risk managers can then use this list to match assessment endpoints
to the management goal (see handouts in appendix C). By the end of the problem formulation
step, risk assessors should understand the risk manager's goal and what endpoints will generate
the types of information that will be most useful to the risk manager. Ed Bender asked the
attendees to consider these questions during the breakout group session, apply the cumulative
risk problem formulation framework to the case studies under discussion, brainstorm a list of
possible risk dimensions and elements, and discuss the implications of these risk dimensions for
risk assessors and risk managers.
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Risk Assessment/ Management Decision Process
New Management Needs
I
Planning
and
Scoping
(Assessor-
Manager
Dialogue)
Risk Assessment
.—•——
'roblem
.Formulatioft-
Risk Analysis
Risk
haracterization/
Economic, Poli-Science,
and Social Analysis
Figure
7. Cumulative Risk Project's proposed framework for risk assessment/management,
-------
Assessor-Manag^
Dialog
Risk Assessor
1. Background Knowledge]
a. scale of the risk
b. critical endpolnts
2. Available/appropriate
data (where?)
3. CR Matrix
4. Gaps
5. Potential RM options
Stakeholders
l.Values
!2. Impacts
Risk Manager
1. Why is RA needed?
2. Management goals
3. Policy concerns
4. Political concerns
5. Timing/Resources
6. Acceptable Levels of
uncertainty?
7. Potential RM options
Economists
L Affected Groups
2. Equity of Impact]
Problem Formulation
Figure 8. Cumulative Risk Prplect's concept of th'e Assessor-Manager Dialogue.
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CASE STUDY OVERVIEWS
Case study authors from EPA offices and regions introduced the attendees to the four
cases to be discussed in breakout groups (see section 3) following the opening plenary session.
Lavaca Bay
Jon Rauscher, a lexicologist in Region 6's Superfund program, presented a brief overview
of the Lavaca Bay case study. The site under examination consists of about 3,500 acres of an
active facility owned by the Aluminum Company of America (ALCOA), a 400-acre dredge spoil
island created by ALCOA, and portions of Lavaca Bay that could encompass an area as large as
60 square miles. In 1988, the Texas Department of Health issued a fishing advisory closing an
area of Lavaca Bay to the taking of finfish and shellfish due to mercury contamination. Region 6
conducted a preliminary risk assessment to characterize environmental conditions and the nature
and extent of contamination at the site, resulting in the addition of the site to the National
Priorities List (NPL), the list of Superfund sites slated for remediation. The community in the
area has been actively involved, putting together, for example, a trilingual (English, Spanish,
Vietnamese) sign to warn fishers against taking and eating fish from the bay.
An unusually large amount of information was available for the Lavaca Bay assessment.
The case study prepared for this meeting series addresses only exposure to mercury as a result of
fish consumption, but the actual assessment covered much more. Jon Rauscher highlighted
several risk characterization issues for the attendees to consider when discussing the case study:
Use of default fish consumption rates to estimate exposure to methyl mercury
from consumption of fish from the site (despite the presence of subpopulations
with different fish consumption patterns).
Use of the reference dose (RfD) for methyl mercury, which is based on studies
involving circumstances that differ from site conditions.
Results of the preliminary risk characterization.
Development and use of site-specific fish consumption rates for further risk
assessment studies.
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Development and use of site-specific toxicity values for methyl mercury.
Cumulative risk from multiple contaminants and multiple pathways at the site.
Midlothian
Jeffrey Yurk, a Toxicologist in the Multimedia Planning and Permitting Division of the
Oklahoma/Texas RCRA Permits Section of Region 6, presented a brief overview of the
Midlothian case study. This case involves a risk assessment conducted to support the State of
Texas's consideration of an application by a cement kiln to burn hazardous waste as fuel. Under
RCRA, all permits are required to be protective of human health and the environment. Under
the Hazardous Waste Minimization and Combustion Strategy announced by EPA in 1994, risk
assessments are conducted to determine whether permit conditions will be protective. The
Midlothian case began as a screening level assessment focusing on human health, but evolved
into an intermediate assessment when Region 6 sought additional data to determine the
significance of potential risks identified during the initial analysis. Moreover, the case is an
example of a cumulative risk assessment because it not only examines the impact of the applicant
(the cement kiln), but considers the cumulative risk associated with all major facilities (total of
three combustion facilities and one steel mill) in the Midlothian area. In fact, it is the first
RCRA risk assessment in the country to address exposure from more than one source.
To conduct the assessment, Region 6 characterized the study area (the Midlothian area)
and used models to analyze plumes of contamination resulting from emissions from the
combustion facilities and steel mill; where the plumes overlapped, Region 6 added them to
characterize total contaminant levels. In this way, Region 6 identified maximum exposure points
(located around each facility) and selected receptors near those points. The analysis yielded
hazard indexes (His), some of which were greater than one. Due to a number of uncertainties
(accuracy of modeled numbers, data gaps, use of surrogate data, etc.), Region 6 returned to the
area to obtain measured data and other information to evaluate the reasonableness of the results
of the initial analysis. The measured values were less than the modeled values, leading Region 6
to conclude that exposure levels and risks are probably lower than levels of concern. Region 6
also analyzed the relative contributions of the studied sources, concluding that the steel mill
(which is outside the program's jurisdiction) is the major contributor to total exposure/risk levels.
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Jeffrey Yurk concluded his overview by noting that stakeholder concern has prompted the
region to conduct the risk assessment, and stakeholders were involved throughout the assessment
process.
Biocrude
Becky Daiss, an Environmental Protection Specialist with OSW, presented a brief
overview of the Biocrude case study. The case study consists of a multimedia baseline risk
assessment conducted to determine whether biocrude (a hypothetical waste stream) should be
listed as a hazardous waste under RCRA. Under RCRA, a waste is considered hazardous if it
exhibits one of four hazardous characteristics (ignitability, corrosivity, reactivity, toxicity) or is
already listed as hazardous in RCRA regulations. To make Hazardous Waste Listing
Determinations, OSW conducts multimedia baseline risk assessments. This case is an example of
a cumulative risk assessment in that it considers multiple waste constituents and pathways; in
addition, it examines risks to both human health and the environment (in separate components).
Like other OSW baseline risk assessments, this case draws on a significant amount of
facility-specific information (waste characteristics, disposal practices) and general information
about the area (meteorological conditions, types and locations of receptors, soil characteristics,
exposure durations and frequencies). OSW identified several areas of uncertainty in the human
health and ecological risk assessments (biotransformation, effectiveness of runoff controls,
biotransfer factors, use of individual-level benchmarks and generic ecosystems, etc.), highlighting
those most likely to affect the recommendation to list biocrude as a hazardous waste. OSW
attempted to write the case study in a way that would make the risk assessment's scope and
focus, risk conclusions, and key limitations and uncertainties clear to a range of audiences—up to
and including risk managers and decision-makers.
Waquoit Bay Watershed
Suzanne Marcy, a Senior Scientist for Ecology with ORD's National Center for
Environmental Assessment (NCEA), presented a brief overview of the Waquoit Bay case study.
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She began by explaining that this case study differs from the others in two ways: it is a problem
formulation product rather than a risk characterization, and it was initiated by community
interest rather than statutory requirements. Groups concerned about the changing quality of the
Waquoit Bay submitted a proposal to EPA suggesting that the bay be the subject of one of the
case studies EPA is seeking to develop on the application of ecological risk assessment principles
to watershed problems. The project is intended to expand the process of ecological risk
assessment and demonstrate its value for community-based efforts to protect ecological
resources. Region 1 and OW and ORD, cosponsors of the project, undertook an extensive
problem formulation effort to define the problem and plan the risk assessment with significant
community involvement. In so doing, they strove to achieve many of the goals and criteria
discussed in Administrator Browner's risk characterization policy and EPA office/regional
implementation statements.
The Waquoit Bay Watershed is a small estuary with fresh water ponds and streams on the
south coast of Cape Cod in Massachusetts. Subject to many stressors (nutrients, toxics, altered
flow, suspended sediments, disease, habitat alteration, harvest pressure), the watershed is showing
many signs of deteriorating quality (replacement of eelgrass by mats of macroalgae, fish kills,
disappearance of scallops, contamination, etc.). To help define the problem, OW and ORD
developed a conceptual model listing activities in the watershed, their associated stressors, the
ecological effects associated with these stressors, assessment endpoints, and measures used to
evaluate the endpoints.
In this case, EPA identified assessment endpoints not by considering a facility or chemical
of concern (as is typically done in traditional assessments), but by convening public discussions
about watershed quality issues of concern to the community. Specifically, EPA held discussions
with risk managers (broadly defined to include all interested parties in the community and
elsewhere) to develop a general management goal, which they broke down into management
objectives and assessment endpoints. Community involvement was a hallmark of this effort. The
process of defining the management goal involved several public meetings to identify concerns
and issues and draft and achieve consensus on the management goal. In providing this overview
of the case study, Suzanne Marcy reiterated that the case's problem formulation process and
product are generally consistent with the goals being developed for risk characterizations.
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SECTION THREE
BREAKOUT SESSION
The opening plenary session was followed by a breakout session designed to give the
attendees an opportunity to explore risk characterization issues—particularly as they relate to the
risk assessor/risk manager relationship—in the context of four case studies (Lavaca .Bay,
Midlothian, Biocrude, Waquoit Bay). The attendees divided into four groups, whereupon they
heard a brief presentation of a case study and discussed the case at length. The attendees were
randomly assigned to groups to ensure that each group included a cross-section of attendees (risk
assessors and risk managers, personnel from different EPA programs and offices). Case
presenters, chairs, and facilitators for the groups are listed in appendix D, case study handouts
are reproduced in appendix E, preliminary risk characterization implementation statements
provided at the meeting are reproduced in appendix F, and Administrator Browner's risk
characterization policy package is provided in appendix G.
The paragraphs below summarize the main points discussed during the breakout group
session.
LAVACA BAY
The Lavaca Bay case study involves a Superfund preliminary risk assessment conducted to
determine whether immediate action is necessary to reduce risk associated with consumption of
contaminated fish, with mercury being the major contaminant of concern. The site is unusually
"data rich", and the case study presents the risk manager with several options for decision-
making.
Members of the Lavaca Bay breakout group looked briefly at a summary of the criteria
for judging the adequacy of risk characterizations (taken from the Region 6 preliminary
implementation statement, see appendix F) and were asked to keep these in mind throughout the
discussion. The major part of the discussion dealt with identifying (1) additional information that
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managers might need from the risk characterization to make a decision and (2) other concerns
that might enter into decision-making. Participants wrapped up the breakout session by working
through the Cumulative Risk Project's Outline of Risk Dimensions and Elements (see appendix
C) as part of a planning and scoping exercise for the second phase, complete baseline,
cumulative risk assessment for Lavaca Bay.
Management Concerns
Following a complete briefing on the site history and risk characterization, members of the
Lavaca Bay breakout group identified several issues and questions that a manager might raise:
• Potential for shifting contaminated sediment and probability of hurricanes.
• Distribution of mercury within the sediments; hot spots.
• Long-term persistence of mercury.
• The nutritional needs of the population.
» Number or fraction of population that is both sensitive and have high exposure
(e.g., pregnant women in subsistence fisher families).
• Populations of concern (adults or children)—can the decision be based on single
group?
• Relationship of reference dose (RfD) to acute levels or other more dramatic
toxicologjc outcomes.
• New studies and their effect on the RfD.
• Is the uncertainty in the toxicity data comparable to uncertainties in toxicity data
for other sites?
• Effects on future pregnancies after exposure is discontinued.
• Confidence in the hazard quotient (HQ); how much would the HQ need to
change to affect the decision?
« Are health effects occurring in the current population?
• Are assessment results like to change much when multiple chemicals are factored
in?
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Breakout group participants recognized that some issues are part of risk management
rather than risk characterization. Risk managers make decisions based not only on the risk
assessment/characterization, but also on economic issues, political factors, social factors, legal
issues, and values. Sometimes, the distinction between risk characterization and these other
factors is unclear. Risk managers for Lavaca Bay might raise the following additional issues and
questions:
• Setting a precedent—given that other sites may be eligible for cleanup based on
this action level, will our decision indemnify the entire coast?
• What is background and how would some remediation affect/benefit background?
Is there a need to act outside the study area?
• Value of the ecosystem.
• Effectiveness of current institutional controls.
• Impacts of dredging.
• Disposal of dredge material.
• Chances of success with judge, state, etc.
» Cost of remedial options.
• Effect of actions on local economy, especially commercial fishers.
• Can mercury be made more benign?
Although theoretically the risk manager has three decision options available (no further
action, immediate action, further study), breakout group participants felt that information in the
risk characterization is sufficient to warrant action while awaiting completion of the baseline
cumulative risk assessment and, indeed, that it is important to take immediate action. Possible
actions include remediating hot spots only, initiating more institutional controls, remediating the
source ("armor dredge island"), capping the source, closing a larger area to commercial fishing,
and educating the population. More importantly, the risk manager needs to determine the level
of cleanup based on the risk characterization and other factors (see figure 3). He/she will need
to determine who will be protected and what action will be most effective, and he/she will need
to involve stakeholders to avoid public outrage over possible effects on the local economy.
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Planning and Scoping the Risk Assessment
Members of the Lavaca Bay breakout group used the Cumulative Risk Project's Outline
of Risk Dimensions and Elements to discuss planning and scoping for cumulative risk in the
context of preparing for the complete baseline risk assessment for Lavaca Bay. Participants felt
that the outline is generally a useful tool for focusing and defining the scope of a risk assessment
during discussions with managers and/or stakeholders. It also encourages some thinking "outside
the box." However, the utility of the outline as a tool could be lost if undue visibility or
emphasis is placed on stressors outside the EPA mandate (e.g., the stress of living in a high
crime area and the resulting cumulative risk on health). Two problems were identified in the
discussion. In Superfund, land use is determined during planning/scoping and becomes the basis
for determining other elements within the dimensions; the outline does not incorporate land use
decisions. Also, the breakout group had difficulty interpreting the intended meaning of
Dimension F, Time Frames.
Lessons Learned
In summary, several themes emerged as lessons learned from the discussions that took
place during the Lavaca Bay breakout session:
Risk managers might not always ask the right questions; risk assessors might need
to educate.
The costs of being wrong, both in terms of human health and economics, drive
the need to narrow uncertainties at Lavaca Bay.
Institutional controls might be inadequate for a large ecosystem over a long
period.
Hard toxicity data combined with exposure to a subsistence population and low
uncertainties create a real need for action ("real people, real exposures").
Supporting claims from other agencies helps in making decisions.
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MIDLOTHIAN
Participants of the Midlothian breakout group included EPA Headquarters personnel and
Region 6 staff and managers from the Pesticides, Air, Hazardous Waste, Superfund, and Water
Divisions. Region 5 and Region 7 managers and EPA/City government Brownfields project
managers also attended the session. The session began with a short explanation of Region 6's
preliminary risk characterization implementation statement by Gerald Carney and a presentation
of the case study by Jeffrey Yurk (a risk assessor in Region 6's RCRA program). The
Midlothian risk characterization describes a screening analysis, so categorized based on the
following criteria in.Region 6's preliminary implementation statement:
Category I: Screening analyses (limited resources, little or no site sampling,
modeling used).
Category II: Intermediate (some monitoring and sampling, permit-related
activity, supported by regional guidance and national standards).
Category III: Baseline (extensive literature review and data documentation,
resource demanding, site sampling and monitoring required, regional and national
regulations and guidelines used).
During and after the case study presentation, participants discussed risk management and
region-state-Headquarters coordination. Topics and comments included the following:
The difference between the information regional managers need to make a
decision and the information risk assessors need to perform a risk
assessment—are there limits to the amount of data needed?
Should we allow attorneys to keep asking for more analysis, especially given that
attorneys are not trained in risk assessment technology?
Managers should be involved from the beginning.
Risk assessors are concerned that decisions are made before the assessment is
performed (i.e., based on nonscience issues).
The risk assessment process needs to be streamlined—industry and EPA are
spending a great deal of money on data and uncertainty analyses.
How should Brownfields risk analyses be addressed in manager-assessor
communications and level-of-effort/resource expenditure decisions?
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When will more inexpensive risk screens (e.g., the underground storage tank
program's RBCA analyses) be allowed?
Current RCRA and Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) regulations do not require cumulative risk analysis.
The present regional risk communication structure does not facilitate up-front
communications between risk assessors, line managers, Remediation Project
Managers, and On-Site Coordinators.
Regional personnel must consider "staying out of the state's way" to minimize
conflict between states and the region.
Cumulative risk analysis guidelines that address/reflect current statutory language
and limitations need to be developed.
Key points of discussion included regional personnel's need for state, region, and
Headquarters coordination; the fact that regional managers vary widely; the limits of legal
involvement; statutory requirements for cumulative risk assessments; and the need for early
dialogue between risk assessors and risk managers. Breakout group participants brought up and
discussed the Risk Assessment/Management Decision Process (see figure 7) many times during
the session. Hie process emphasizes planning and scoping, the assessor/manager dialogue, and
input from stakeholders. Designing an infrastructure that permits open discussions of human
health, ecological, and socioeconomic risk issues prior to the formal risk assessment is completed
may require a significant culture change in both EPA Headquarters and the regions.
BIOCRUDE
Members of the Biocrude breakout group felt that EPA's risk characterization policy is
needed, that the values of TCCR are appropriate, and that Region 6 has begun to put the risk
characterization policy into practice. Region 6 participants expressed concern about the
cumulative risk proposal, however. They were particularly concerned about resource limitations
(personnel, information on risks outside the program's or Agency's jurisdiction).
The Biocrude case study served to highlight several issues surrounding risk
characterization and triggered comments about risk characterization documentation, risk
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assessor/risk manager interactions, risk assessment/risk characterization infrastructure needs, and
miscellaneous lessons learned.
Risk Characterization Documentation
Members of the Biocrude breakout group agreed that the case study, as presented in a
briefing format, is appropriate for the intended audience (a sophisticated Headquarters program
manager). They noted, though, that the conclusions were implied instead of explicitly stated and
that the risk was not compared to other similar risks as required by the OSW and Region 6
preliminary implementation statements. Suggestions for improvement included:
• Explicitly state the conclusion(s).
• Identify key strengths and uncertainties (those that impact the bottom line by an
order of magnitude or more) and separate them from minor ones; consider
ignoring the minor ones altogether.
• Memorialize the risk characterization for subsequent users (e.g., in the region,
states, for legal challenges, etc.).
• Document the assessors' conclusion about how "real" is the risk.
— What is the "behavior" of the individual involved in the risk (what is the
lifestyle pattern)?
— Does a population of individuals with this behavior/risk exist?
• Make the risk characterization more understandable by using simple, plain
language and appropriate analogies. (Some participants felt that it is appropriate
to compare the risk to familiar risks, such as dying from a lightning strike, as long
as the risks are correctly placed in context. Others felt that comparisons should
be limited to other risks that EPA regulates. All agreed, however, on the need
for a simple "plain talk" approach.)
• Present alternative assessments using different assumptions to show plausible
alternatives and to estimate the impact of a "no action" decision.
• Examine what other EPA regulatory entities are doing to better integrate
regulation across programs.
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Breakout group members noted that assessments (like Biocrude) performed to support
national standards cannot be specific because of the tremendous variation in terrain, population,
weather, and other factors across the country. Site-specific assessments are more specific and
"real." The participants felt that this reinforces the need to memorialize the risk characterization,
so that site-specific users of the document can appropriately deal with the uncertainties involved
in the national assessment as they go about making the assessment "real."
Risk Assessor/Risk Manager Interactions
This discussion focused on (1) the need to find common, understandable terminology and
(2) the need for risk assessors to be involved from the beginning in the activities that lead to
decision-making. Breakout group members used the watch phrase "Involve 'em early and often."
Risk Assessment/Risk Characterization Infrastructure Needs
Members of the Biocrude breakout group clearly recognized and understood that EPA's
risk characterization policy emphasizes the need to explain what was done honestly and openly;
uncertainty, lack of information, and so on are not excuses for a failure to be clear, open, and
transparent. To achieve consistency and reasonableness, however, the participants felt that EPA
will need to improve its infrastructure. They identified the following infrastructure needs:
Better guidance, documentation, and default values for exposure, especially
certain exposure-related processes (bioconcentration, dermal uptake,
biodegradation).
Guidance on how to handle multiple risks from multiple exposures.
Model validation as well as greater consistency in the assumptions, parameters,
and models, used across EPA and the states. Breakout group members suggested
appointing a group to identify "core assumptions" and develop, improve, and
sanction models and data sets.
Clarification of partnerships between the generator of methods, models, and data
for use by others (i.e., ORJD) and the users (i.e., program offices, regions, states).
An ongoing, effective process is needed to identify the most appropriate models,
databases, and defaults; to update them; and to disseminate them.
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Lessons Learned
Members of the Biocrude breakout group felt that, as the risk characterization and
cumulative risk policies are implemented across EPA, it is important to remember that:
You cannot please all the people all the time; nevertheless, if you have a process
in place that is perceived to be fair and just, you can reach decisions that people
will accept.
Risk communication starts before risk characterization is complete.
More focus on ecological impacts is needed. No one knows how best to
characterize ecological risks.
Peer review as currently practiced at EPA is not working well. Developing an
appropriate charge to reviewers is critical. Currently, charges to reviewers tend to
be too focused; reviewers should also be asked to identify what is missing.
WAQUOIT BAY
The Waquoit Bay case study differs from the other case studies discussed at this
colloquium in that the bay is one of five watersheds selected for study with the aim of developing
a comprehensive watershed risk assessment process. Using EPA's Ecological Risk Assessment
Framework as a starting point, the study has concentrated solely on an ecological risk assessment
of an environmentally impacted watershed. The case study documents the planning and scoping
process completed to date and the resultant problem formulation and analysis; the risk
assessment itself has not been completed, so the case study does not include a risk
characterization. Experience to date with this and the other four watersheds under study has
served as a basis for developing EPA's proposed Ecological Risk Assessment Guidelines. Thus,
many of the Waquoit Bay problem formulation steps discussed in this colloquium were presented
in the context of the proposed guidelines. Discussion centered on the processes of planning and
scoping, problem formulation, and analysis—and how these processes might influence the
assessor/manager dialogue.
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Planning, Scoping, and Problem Formulation
The Waquoit Bay case study was presented in terms of the basic approach described in
EPA's proposed Ecological Risk Assessment Guidelines in which the initial planning process
involves a dialogue between risk assessors and risk managers. The case study uses a broad
definition of risk manager: anyone who influences risk reduction. This definition stimulated
considerable discussion. Some breakout group participants agreed that anyone who impacts the
ultimate risk reduction, no matter how small a contribution he or she makes, can be considered a
manager of risk; risk managers outside of EPA Headquarters might include state and local
officials and the affected public. Other participants contended that a risk manager is an
individual who makes a decision that will impact resources, efforts, and people; such an
individual might be a section head, division director, or responsible official. Some participants
stated that each region has only one risk manager, the Regional Administrator.
Breakout group participants went on to discuss the role of stakeholders or, more
pointedly, interested parties. The National Research Council's recent publication Understanding
Risk advocates extensive involvement of stakeholders at most stages of risk characterization.
Breakout group participants offered examples of stakeholders (state and regional representatives,
societies, associations, impacted neighborhoods) that could be involved. Some went so far as to
include as much of the general public wishing to participate, while others limited involvement to
interested parties. Guidance on what constitutes an interested party or stakeholder—and how to
communicate with and properly involve the party—seems to be needed.
The Waquoit Bay planning process brought together many interested parties, including
risk assessors and risk managers from several state and federal agencies, academics, associations
concerned with the area, and citizens from the impacted area. These parties helped examine the
scope and complexity of restoring this watershed and contributed to the development of a
management goal The management goal—to reestablish and maintain the watershed for native
populations—was constructed to facilitate problem formulation.
As described in EPA's proposed Ecological Risk Assessment Guidelines, problem
formulation serves as the foundation for the risk assessment. Some breakout group participants
suggested that a risk assessment is only as good as the planning, scoping, and problem
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formulation. The elements of problem formulation correspond to the elements of risk
characterization; that is, one goes through the same process in problem formulation and risk
characterization, but one uses analyzed data in the risk characterization. If probJem formulation
is done well, the risk characterization is relatively easy.
Successful completion of the problem formulation step yields three products: assessment
endpoints, conceptual models, and an analysis plan. To develop these products for the Waquoit
Bay case study, those involved in the effort assessed available information on the characteristics
of the watershed, observed ecological effects, and possible stressors. The case study included
specific information on these topics.
An assessment endpoint includes the entity and its attributes. For Waquoit Bay, some of
these include estuarine eelgrass abundance and distribution, finfish diversity, and bacterial and
contaminant content of fish and shellfish. The idea of susceptibility was discussed—whether the
endpoints are susceptible to adverse exposure and/or are sensitive to a stressor or combination of
stressors. Societal goals (upgrade of recreational uses, sustainable fish and shellfish populations
for commercial uses) are assessment points that need to be addressed in the problem
formulation.
After identifying assessment endpoints and stressors, Waquoit Bay case study authors
developed a conceptual model (in the form of a flow chart) to allow examination of possible
interactions between endpoints and stressors. The conceptual model represents a series of risk
hypotheses about the relationships between particular stressors and ecological effects (e.g.,
nutrients stimulate increased algal growth, which can contribute to eelgrass decline). Breakout
group participants appreciated the visual presentation of the conceptual model, commenting that
it facilitates easy communication of proposed interactions and will aid future examination of the
interactions. The participants further noted that developing a conceptual model permits
communication and peer review of the thought process shaping the assessment (and thus
correction of any misperceptions that might exist) and helps ensure that assessment efforts are
proceeding in the proper direction.
In ecological risk assessment, the conceptual model and risk hypotheses serve as a basis
for an analysis plan. In developing such a plan, risk assessors and risk managers choose what
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measures or directions will be taken (without making decisions about final outcomes). They
collect and evaluate available data, select measures to examine, choose proper analytical tools,
and characterize exposure and ecological effects and their interrelationships. The latter lead to
stressor-response profiles (e.g., increased nutrient load in the watershed leads to increased algal
growth).
Assessor/Manager Dialogue
At this point, the breakout group discussion turned to issues related to the
assessor/manager dialogue in risk characterization:
Risk assessors and risk managers should maintain a respectful dialogue
throughout the risk characterization process. Each brings a perspective that
needs to be recognized by the other, and the two perspectives may lead to
different needs and outcomes. The dialogue should recognize (respect) both
perspectives and harmonize the two sets of needs and outcomes.
The assessor/manager dialogue is beneficial in that it provides an opportunity to
learn about each other's constraints and appreciate each other's situation.
Both risk assessors and risk managers need to understand that in many (almost
all?) instances, a definitive "number" cannot be generated and absolute certainty
is unattainable.
A risk assessment does not make a decision, but informs the decision. The risk
manager should recognize that it is his/her responsibility to make the decision
based on consideration of all the facts, including risk assessment results.
Risk assessors, having developed the risk assessment and risk characterization, are
in a position to know the full implications of the risk assessment and should have
an opportunity to provide their opinions about decision options. Some breakout
group participants felt that providing such opinions will illuminate the assessor's
bias, possibly compromising the assessor's credibility. Risk managers, on the
other hand, probably consider factors that the risk assessor might know less
about. Breakout group participants generally agreed that risk managers would
like to hear the risk assessor's opinion, but the opinion should be presented
separately (as an opinion) from the risk assessment/risk characterization.
Moreover, the risk assessor should understand (respect) that the risk manager
makes the decision and might not agree with the risk assessor.
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Risk manager want the following from risk assessments:
— Defensible information (to help make the decision "more translatable" to
customers outside the Agency, such as tribes and states).
— Timeliness and good use of monies.
— Good science with a set of explicit explanations (not research for the sake
of research).
— Quantitative risk information, where appropriate (especially for Superfund
uses).
— Risk assessment/risk characterization documents tailored for different
levels of understanding (different audiences).
— Simpler, easier to understand risk information as well as full technical
information.
Lessons Learned
Several lessons emerged from the discussion of the Waquoit Bay case study. The most
important is the value of spending time (i.e., on an assessor/manager dialogue, problem
formulation) at the outset. Spending time up front will ultimately save time and resources—it
will promote buy-in by stakeholders or interested parties, lead to a better informed decision, and
result in less controversy (e.g., fewer court cases, criticism).
Other lessons learned include:
The management goal is the ecological value to be protected. (This can also be
the case in human health or other assessments.) The goal should not be a
preconceived decision that renders the subsequent risk assessment and risk
characterization irrelevant.
Although the Waquoit Bay case study is an ecological risk assessment, human
health risk assessments can benefit from similar up-front planning and problem
formulation.
A consistent process for decision-making would allow use of professional
judgment and other factors in making a decision. By avoiding thinking in terms
of "we've done it this way before", risk managers will be free to consider the full
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range of professional judgments and other factors rather than being constrained
by prior decisions.
Staff and manager training on all aspects of planning, problem formulation, risk
assessment, risk characterization, and risk communication would greatly facilitate
and enhance the whole process, especially the assessor/manager dialogue. Peer
review of parts of this process (e.g., the conceptual model) would provide
incentives to sharpen each product and would help establish the validity and
credibility of the analyses, models, and conclusions made. Peer review leads to a
better work product to further inform and enhance the information needed for a
decision.
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SECTION FOUR
CLOSING PLENARY SESSION
HIGHLIGHTS FROM BREAKOUT SESSION
Following lively breakout group discussions, the attendees reconvened in a plenary session
to review the key risk characterization/risk management issues they had identified. These issues
are summarized in section 3 in more detail. Asked to encapsulate their main points of
discussion, members of the Lavaca Bay group offered six lessons learned:
• The risk manager might not ask all relevant questions; the risk assessors needs to
educate the risk manager.
• Hard data on toxicity combined with a subsistence population and a low degree of
uncertainty create a real need for action. The question is who to protect and how
rather than whether to act at all.
• The human health and economic costs of being wrong are driving the need to
narrow uncertainty to ensure that resources are spent wisely.
• Institutional controls may be inadequate in a large ecosystem over time.
• Support from other agencies (e.g., concern about a problem or agreement that a
problem exists) helps in making decisions—and in communicating problems and
decisions to the public.
• A framework for planning/scoping cumulative risk assessments would be useful.
Planning/scoping promotes dialogue, discussion of management objectives, and
discussion of risk management objectives and it leads to problem formulation.
Members of the Midlothian group identified the following as key issues:
• State/EPA coordination. In the Midlothian case, the state conducted an analysis
of one facility; based on community concern, EPA subsequently undertook a
cumulative risk assessment. In such cases (dealing with cumulative risk), when
and how should coordination begin?
• Definition of risk manager. Is the risk manager the remedial project manager?
The branch chief? The regional administration?
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• Legal involvement. When is there enough analysis? Litigation concerns often
drive data collection, but this runs counter to streamlining efforts.
• Definition of cumulative risk (multiple chemicals, sources, media). What statutory
requirements and limitations influence how cumulative risk is addressed?
• Assessor/manager dialogue. What are the implications of encouraging early
dialogue? How will it work to consider economic, political, and social issues early
in the process? These questions point to a need to document the decision-
making process.
Members of the Biocrude group offered the following suggestions for improving risk
assessment/risk characterization documentation:
• Identify and quantify key strengths and uncertainties (those that drive the bottom
line).
• Explain how real are the risks. What is the behavior/lifestyle of the individual
subject to the risk? Nationally, does a population of such individuals exist?
• Explain risk in "plain talk."
• Discuss how the risk would change if different assumptions were used or if no
action were taken.
They also offered some more general observations about risk characterization:
Risk characterizations for national standard pose different difficulties than those
for site-specific assessments, making it particularly challenging to fully comply
with the risk characterization policy (e.g., the call to examine ecological risk in all
risk assessments).
It is important to communicate and integrate with other programs/regulatory
entities. In particular, it is helpful to know if other programs are examining the
same sites/problems and, if so, what results they are getting.
EPA needs to identify "core assumptions" for use in risk characterizations. For
example, certain uncertainties come up again and again; having a set of core
assumptions to work with will help risk assessors address these uncertainties and
assumptions clearly. Where possible, EPA needs to develop, improve, and
sanction data sets and explicitly give risk assessors the authority to override those
data with site-specific data.
EPA needs to clarify partnerships between ORD, program offices, regions, and
states. In so doing, EPA needs to identify key problems for ORD (those that
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keep coming up) and indicate what defaults, data sets, etc. risk assessors should
use while ORD is working on the problems.
Peer review is useful (and can help ward off problems and criticisms), but the
charge to the peer reviewers is critical to ensure that the feedback is useful. Risk
assessors need feedback on the overall reasonableness of the assessment, whether
there are holes in the assessment, and so on.
Members of the Waquoit Bay group commented that:
At all points, those involved in risk assessment/characterization need to maintain
a respectful dialogue.
Risk assessment does not make the decision, but informs it. (Risk managers do
not and cannot expect decisions from risk assessors.)
A risk assessment cannot generate a definitive number or provide absolute
certainty.
The risk manager is the person or group that takes responsibility for the decision.
Whether risk assessors should provide their opinions about decision options
remains controversial.
A Waquoit Bay group cochair asked the attendees whether they think risk assessors
should offer their opinions about decision options. The attendees who responded generally
answered in the affirmative. For example, one risk manager said that he wants all available
information and opinion. Others agreed, commenting that risk assessors (like everyone else) can
be biased and risk managers simply need to know that and take that into account—just as they
do when listening to the perspectives of lawyers, economists, and others. Using a newspaper
article versus editorial page analogy, one risk manager suggested that risk assessors clearly
separate fact and opinion, first making a "neutral" presentation on the risk assessment and
separately (later) offering their opinions.
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Members of the Waquoit Bay group also identified several lessons learned:
• Risk manager can be defined as anyone who influences risk reduction.
• The management goal is the ecological value to be protected, not a preconceived
decision.
• Consistency in the process allows use of professional judgment and site-specific
decisions.
• Spending time up front (in planning/problem formulation) is valuable because it
saves time and resources, facilitates buy-in, and helps reduce controversy and
litigation. Risk characterization is only as good as the planning/problem
formulation that went into it.
• Human health risk assessment can benefit from planning/problem formulation.
Agreeing that planning/problem formulation is useful, one attendee suggested that the
process can help identify the priority that an assessment should have so that the participants can
allocate their resources accordingly. Others agreed, reiterating that the participants should work
collegially from the beginning to achieve agreement on the priority and scope of the assessment;
this may be difficult when the participants belong to different organizations or work in different
buildings/parts of the country. Nevertheless, this has been successfully done (e.g., at Lavaca Bay,
in the Superfund program, in ecological risk assessments) and often results in a more reasoned
decision from the risk manager.
These comments led to a discussion of peer review. Several attendees noted that different
types and levels of peer review are appropriate in different circumstances. Others suggested that
EPA should expect contractors and stakeholders to maintain the same level of scientific
integrity/peer review that the Agency expects of itself. A couple of attendees noted that they
typically discuss their expectations with registrants and other external groups at the outset and
that the products they receive typically reflect that guidance.
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RISK MANAGERS' ROUNDTABLE DISCUSSION
After this review of breakout group discussions, a panel of risk managers offered their
perspectives on risk characterization issues. Both following each manager's remarks and after all
the managers had spoken, the risk managers and audience engaged in discussions of issues
raised.
David Cozad
Branch Chief, Office of Regional Counsel, U.S. EPA Region 7
David Cozad began his remarks by explaining his role in risk assessment: to advise risk
managers on the legal defensibility of risk assessments. Although the courts do not typically
question science decisions, he said, it is important to document assumptions and decisions as
thoroughly as possible throughout the risk assessment process; the more specific the
documentation the better. David Cozad noted that risk assessors sometimes worry that site-
specific results will differ from results developed at other sites and therefore choose to use
defaults instead. Stating that consistency of process is more important than consistency of
results, he urged risk assessors to use site-specific data where appropriate and document these
choices. Similarly, he urged risk assessors to clearly explain uncertainties up front—that this
enhances rather than detracts from the defensibility of risk assessments.
David Cozad went on to address other issues, stating that he favors:
• Dialogue and involvement in planning and problem formulation.
• Guidance that emphasizes consistency of process and use of judgment (rather
than prescriptions).
• Training for all involved in the risk assessment process, especially managers and
others involved in risk communication.
Following these remarks, several attendees asked questions of the speaker. Stating that
his breakout group had spent a great deal of time discussing the question of how much
documentation is enough, one attendee asked David Cozad for his thoughts. David Cozad
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replied that no single rule of thumb applies to all cases. Lawyers prefer as much site-specific
data as possible (when the data are of sufficient quality) but recognize that cost constraints and
other factors influence how much data and documentation can be assembled. He suggested that
risk assessors explicitly state what was and was not done and why.
Other attendees asked related questions, such as how to deal with situations in which the
threat of litigation arises at some point during the risk assessment process, changing what
managers/lawyers want from risk assessors. Agreeing with an attendee who suggested that EPA
explore ways of communicating legal issues early on in the process, David Cozad noted that
lawyers in Region 7's Superfund program are involved in risk assessments from the start. He
acknowledged that some lawyers are more familiar with risk assessment issues than others, and
he suggested that lawyers could benefit from more training. David Cozad also acknowledged
hearing occasional complaints about risk managers interfering too much in the risk assessment
process. Nevertheless, the process of inclusion and communication, while still evolving, does
seem to be working.
Gerald Phillips
Corrective Action Manager, Waste, Pesticides, and Toxics Division, U.S. EPA Region 5
Noting that many key points had already been made during the colloquium/roundtable,
Gerald Phillips stated that he would like to emphasize a few points that he considers particularly
important:
• Risk management is a way of doing business. At EPA, different programs tend to
think their way is best, but we need to be open-minded enough to examine the
practices of other programs to see what we can learn.
• Increasingly, the public is wanting government to balance risks. EPA needs to
respond by identifying, considering, and finding a way to balance the full range of
issues (not just environmental protection) surrounding a particular problem.
• Risk assessments should begin with a solid conceptual plan that reflects the input of
several layers of management and an understanding of political issues.
» EPA w not the only organization that can do it right. EPA should clearly state
Agency procedures and requirements to level the playing field and increase the
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likelihood that the Agency receives good results from contractors, industry, and
states.
Not everyone from industry is anti-environment. Some may have a different bottom
line but still have an interest in protecting the environment.
EPA needs to speak in plain English rather than Agency jargon. In some cases,
problems and controversy arise from misunderstanding and frustration—and could
be avoided by better communication.
Gerald Phillips's comments about industry sparked some discussion. One attendee who
used to work in industry agreed that many in industry are concerned about the environment.
Gerald Phillips added that the culture is changing toward partnerships rather than adversarial
relationships. Although EPA still needs enforcement capability to deal with the small percentage
of industrial players who do not care about the environment, most of industry would like to do
the right thing—and most believe that we will all be better off in the long run if we work
together. In response to another question, Gerald Phillips stated that he sees value in bringing
people together early on, at least to the extent possible given time and resource constraints. He
suggested developing a planning tool (such as a checklist) to facilitate the process of touching all
bases early on—and revisiting the plan frequently to see whether the assessment is on track and
whether/how to adapt to change.
Steve Luftig
Director, Office of Emergency and Remedial Response (OERR), U.S. EPA
Noting that he previously was Region 2's Superfund Division Director, Steve Luftig began
his remarks by recalling one of his major projects in Region 2: the Love Canal habitabiliry study,
which aimed to determine whether it was safe to reinhabit evacuated homes. As part of that
study, Region 2 did an excellent job involving the public, states, other federal agencies, and
academia. Having gone through that experience, he praised Administrator Browner's call for
TCCR—and EPA's attitude that we do not have all the answers and are all working on the issue
together.
Steve Luftig went on to discuss the issue of risk in the Superfund program, where EPA
has screened .more than 40,000 sites, has identified 1,300 sites needing action, and has completed
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remediation of about a third of the sites needing action. Clearly, risk is a major issue in the
Superfund program. The program has come under criticism, with some claiming that EPA
focuses on "the kid who dives through a waste pool to eat the sludge at the bottom." Even if this
is a perception problem, the program is trying to change its practices to ensure that risk
assessment results are real and reasonable. Otherwise, Congress might impose action models
requiring basic interventions as the default and cost-benefit analyses to support any additional
action—that is, if Congress reauthorizes the Superfund program at all. Steve Luftig said that he
sees Administrator Browner's risk characterization policy as a tool to help ward off such
undesirable prescriptions.
Indeed, Steve Luftig stated that the Superfund program has already undertaken reforms
that are consistent with Administrator Browner's policy. The program is working to involve more
people up front, perform the problem formulation step, revise the program's risk assessment
guidelines, allow potentially responsible parties to conduct risk assessments (with EPA oversight),
and develop easy methodologies for responding to acute threats. The program is currently
conducting a survey and will hold a stakeholder meeting to collect input on what should be
addressed first so that the program can set priorities. Steve Luftig said that the program has not
yet determined how to address cumulative risk, especially at sites with environmental justice
issues. Addressing this issue will take a long time, he said, but interim answers are likely to be
developed in the shorter term.
The audience responded to Steve Luftig's remarks with a number of interesting questions.
One asked whether Administrator Browner's risk characterization policy would have impacted
Region 2's Love Canal decision. Steve Luftig replied that the decision was made by the State of
New York rather than EPA. He said he did not know if EPA would make a different decision
now, but he does feel confident that the group at the time implemented the principles of TCCR.
Another attendee asked Steve Luftig the same question he posed to David Cozad: how much
documentation is enough? Steve Luftig said he hopes that risk assessors are spared the need to
collect data for cost-benefit analyses (which would be a major undertaking), and that adding
economic and political issues to risk assessments will dramatically increase the complexity and
amount of data to be collected. On the other hand, he said, some congressional legislation
(however undesirable for other reasons) would actually ease risk assessors' jobs by dictating
certain courses of action.
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Myron Knudson
Director, Super fund Division, U.S. EPA Region 6
Stating that over the years he has worked in all EPA programs, Myron Knudson stated
that he believes the principles of TCCR to be incompatible, even mutually exclusive. He cited an
example in which a physiologically-based pharmacokinetic (PBPK) model predicted the same
result that another study found for one site, but two very different results were obtained for a
different site. How does one deal with transparency in that situation, he asked? EPA cannot tell
the public that it is going to clean up one part of a yard to one level and another part to a
different level. Myron Knudson cited other examples, too—of "illiterate" fish that did not know
they were supposed to be dead according to a water quality standard, of telling a community that
a dioxin soil cleanup level of 1 is safe when in fact the number has no rational basis, and so on.
He urged the participants to leave sufficient flexibility in any guidelines that are developed so
that the Agency can be reasonable.
Myron Knudson did agree with other speakers in one regard—that it is important to
involve risk managers up front. Risk managers need to know what is involved in a risk
assessment, he said.
Myron Knudson's remarks prompted a number of responses. One attendee suggested that
EPA might not have been clear about what is meant by transparency—that the transparency
being discussed refers to transparency in the process. Implementing TCCR in the dioxin
situation, for example, might lead a reasonable person seeing the variance in the numbers to
come to the same conclusion that EPA did (i.e., that a level of 1 is safe). Another attendee
added that it would be helpful to provide more context—that simply living and eating in the
United States results in a certain level of exposure that will not be avoided through a local
cleanup. Still another attendee commented that Myron Knudson's presentation of the dioxin
issue was transparent and reasonable, so the method worked and the next step is to determine
how to communicate the reasonable result.
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Bill Honker
AR/OK/TX Branch Chief, Superfund Division, U.S. EPA Region 6
Bill Honker prefaced his remarks by noting that he had focused on regulatory work prior
to joining the Superfund program. As a risk manager, he said, he makes decisions and tries to
communicate and sell them to the public. In recent years, this effort has produced many scars, a
fact that reflects the evolution of risk assessment and corresponding changes in public attitude
over time:
• In 1980, EPA conducted risk assessments on polychlorinated biphenyl (PCB)
combustors as part of the process of reviewing applications. Risk assessment was
new then, and the public appreciated EPA's efforts and accepted EPA's
conclusions.
• In the late 1980s, EPA asked applicants to conduct risk assessments to support
permits for combustors. By that time, the public had become skeptical, viewing
risk assessments as highly manipulable; the public did not readily accept the
results and asked many questions.
• In the early 1990s, many new issues (cumulative risk, societal risk, environmental
justice, etc.) began cropping up and the public began advocating technology-based
standards to ensure that all communities would receive the same level of
protection.
• With increased organization and electronic communication, citizens groups across
the country are more highly educated about risk management decisions (both
local and distant) than ever. This is posing new challenges to risk managers.
Bill Honker went on to note that he has served as Region 6's representative on the RCRA
Review Board. The board reviewed the first several sites without a formula for what to consider;
with experience, the board now knows to focus on risk. In some cases, risk has been adequate
characterized, but the management decision seems to be out of line with the risk (either
overprotective or insufficient). It has turned out that the decisions were based on unsupported
or inadequately documented assumptions. This experience suggests the value of more
consistently applying the principles of TCCR.
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General Discussion
Following the risk managers' remarks, the managers and other attendees engaged in a
general discussion of risk characterization issues. This discussion revolved around the following
questions:
How to determine "real" risk. One attendee noted that assessors performing risk
assessments to support decisions about hazardous waste listings usually describe
the risk to the most exposed individual, but cannot say whether any real human
being actually has that risk. In other situations, the problem (e.g., a hazardous
waste site) poses a high level of risk to a very small number of people. These
situations point to the need for more discussion on what constitutes real risk, how
to determine if a real risk exists, and what the threshold for action should be.
How to devise a suitably protective screening system. Often, the tendency to want to
protect everyone drives risk assessors to use more and more conservative
assumptions; yet, backing away from that conservatism could leave people
unprotected. One attendee observed that the Superfund program's "three times
background" policy was an attempt to bring balance to the screening process but
does sometimes fail to catch problem sites. Another attendee commented that
the Superfund program is intended to address to most egregious problems, while
still another attendee felt that any guidance on the issue should leave room for
best professional judgment.
Whether/how to apply the principles of TCCR to other processes that factor into
decision-making. Risk assessment/characterization is just one of several inputs
into the risk management decision process (see figure 4), and most agree that the
other inputs are far less transparent. Some attendees felt that applying TCCR to
those inputs would be useful, if unrealistic in the short term. One attendee
disagreed, however, stating as an example that most people do not really want to
know what dollar value EPA places on a human life.
NEXT STEPS
Following the risk managers' roundtable discussion, Penelope Fenner-Crisp and Edward
Ohanian discussed next steps in the risk characterization policy implementation process. They
noted that the implementation team initially planned to hold a third meeting in each meeting
series (i.e., "A3", "B3", and "C3" meetings) for risk managers. Experience from the meetings held
to date, however, suggests that it might be more productive to take a step back to consider
progress made and analyze what next steps might produce the "most bang for the buck." Thus,
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the SPC will hold a 1-day meeting in Washington, DC, on September 13,1996, to provide an
opportunity for the meeting chairs and session cochairs from the various colloquia and
colloquia/roundtables to discuss lessons learned and plan for the future.
ADJOURNMENT
Following this discussion, Penelope Fenner-Crisp thanked the attendees for their
contributions and closed the colloquium/roundtable.
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Risk Characterization Colloquiun
C-2
The following attachments relate to the Risk Characterization Colloquium
held in Dallas, Texas on August 1 & 2, 1996
Appendix A Agenda
Appendix B Attendee Registration List
Appendix C Cumulative Risk Assessment Planning
and Scoping Handouts
Appendix D Case Presenters, Chairs and Facilitators
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APPENDIX A
AGENDA
C-2
:Augusi 1&2, 1996, Dallas, Texas
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APPENDIX A
AGENDA
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vvEPA
United States
Environmental Protection Agency
Science Policy Council
Risk Characterization Colloquium
Series C2: OSWER and EPA Regions
Colloquium Chair: Penelope Fenner-Crisp
Le Meridian Hotel
Dallas, TX
August 1-2, 1996
Agenda
THURSDAY, AUGUST I
PLENARY SESSION I
8:OOAM Registration
9:OOAM Welcome to Region 6 Allyn Davis
9:1 SAM Welcome and Opening Remarks Pene/ope Fenner-Crisp
9:30AM Background History of Risk Characterization Margaret Stasikowski
9:50AM Regional Focus for Risk Characterization Gerald Carney
IO:OOAM Highlights From Cl Colloquium Jack Fowle
10:10AM Case Study Summaries Case Study Presenters
IO:30AM Planning and Scoping for Risk Assessment
and Characterization Ed Bender
IO:45AM BREAK
i Printed on Recycled Paper
A-l
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THURSDAY, AUGUST I (Continued)
IhOOAM
I2:OOPM
I:OOPM
2:OOPM
2:t5PM
3:30PM
3:30PM
4:30PM
CONCURRENT BREAKOUT GROUPS
Breakout Session
Case Study A: Lavaca Bay
(OERR, Region 6)
Case Study B: Midlothian
(Region 6)
• Case Study C: Biocrude (OSW)
. Session Chair: Dave Bennett
Facilitator: Ruth Bleyler
Case Presenter: Jon Rauscher
Session Chairs: Gerald Carney
and Cecilia Tapia
Facilitator: Ed Ohanian
Case Presenter: Jeffrey Yurk
Session Chairs: Larry Reed
and Bill Gallagher
Facilitator: Jack Fowle
Case Presenters: Becky Daiss and Dave Cozrie
Case Study D: Waquoit Bay
(OW, Region /)
Session Chairs: Margaret Stasikowski
and Sharon Parrish
Facilitator: Kerry Dearfield
Case Presenter: Suzanne Marcy
LUNCH
Breakout Session (Continued)
Note: Participants are requested to remain in the same breakout session
from the morning for continuity of discussions.
• Case Study A: Lavaca Bay
• Case Study B: Midlothian
• Case Study C: Biocrude
• Case Study D: Waquoit Bay
BREAK
Breakout Session (Wrap-Up)
ADJOURN
EXECUTIVE SESSION
Breakout Group Co-Chairs and Facilitators Meet With Colloquium Chair To Develop
Reports
ADJOURN
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FRIDAY, AUGUST 2
9:OOAM
10: ISAM
IO-.40AM
I2:OOPM
I2:30PM
PLENARY SESSION II:
RISK ASSESSORS' AND MANAGERS' ROUNDTABLE
Risk Characterization/Management Issues
and Reports From Breakout Groups
Colloquium Chair/Session Co-Chairs
BREAK
Risk Managers' Roundtable
Steve Luftig, OSWER/OERR;
David Cozad, Region 7;
Myron Knudson. Region 6;
Gerald Phillips, Region 5;
Bill Honker, Region 6
General Feedback and Discussion
Colloquium Wrap-Up
• Expectations, Outcome, and Next Steps
ADJOURN
Penelope Fenner-Crisp
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APPENDIX B
ATTENDEE REGISTRATION LIST
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vvEPA
United States
Environmental Protection Agency
Science Policy Council
Risk Characterization Colloquium
Series C2: OSWER and EPA Regions
Colloquium Chair: Penelope Fenner-Crisp
Le Meridien Hotel
Dallas, TX
August 1-2, 1996
Final Attendee List
Marilyn Avinger
Brownfields Program Manager
Economic Development Department
City of Dallas
1500 Marilla Street (5CS)
Dallas, TX 75202-2733
214-670-5092
Fax: 214-670-0158
Gary Baumgarten
Project Manager
AK/OK/TX Branch
Texas Section
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-AT)
Dallas, TX 75202-2733
214-665-6749
Fax: 214-665-6660
Ed Bender
Biologist
Office of Science Policy
U.S. Environmental Protection Agency
401 M Street, SW (8103)
Washington. DC 20460
202-260-2562
Fax: 202-260-0744
David Bennett
Senior Process Manager for Risk
Hazardous Site Evaluation Division
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
401 M Street, SW (5202G) - 12th Floor
Washington, DC 20460
703-603-8759
Fax: 703-603-9133
E-mail: bennett.da@epamail.epa.gov
Arnold Bierschenk
Environmental Scientist
Multimedia Planning and Permitting Division
U.S. Environmental Protection Agency
1445 Ross Avenue - Suite 1200 (6PD-A)
Dallas, TX 75202-2733
214-665-7435
Fax: 214-665-6460
Judith Black
Remedial Project Manager
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-AI)
Dallas, TX 75202-2733
214-665-6239
Fax:214-665-6660
E-mail: black.judidi@epamail.epa.gov
i Printed on Recycled Paper
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Ruth Bleyler
Environmental Scientist
Science Policy Council Staff
Office of Research and Development
U.S. Environmental Protection Agency
JFK Federal Building (HBS)
Boston, MA 02203
617-573-5792
Fax:617-573-9662
E-mail: Weyfer.ruth@epamail.epa.gov
Rick Brandes
Chief
Waste Identification Branch
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5304W)
Washington, DC 20460
703-308-887!
Fax:703-308-0514
E-mail: brandes.william@epannait.epa.gov
Carole Braverman
Senior Risk Assessor
Office of Strategic Environmental Assessment
U.S. Environmental Protection Agency
77 West Jackson Boulevard (B-I9J)
Chicago, IL 60604-3507
312-886-2910
Fax:312-353-5376
E-mail: braverman.carole@epamail.epa.gov
Gerald Carney
Toxicologist
Office of Enforcement and Compliance
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-XP)
Dallas, TX 75202-2733
214-665-6523
Fax: 214-665-2146
Chichang Chen
Waste Identification Branch
Hazardous Waste Identification Division
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5304W)
Washington, DC 20460
703-308-0441
Fax: 703-308-0522
James Colon
Federal Facilities Assistant
Enforcement Division
Compliance Assurance
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN)
Dallas, TX 75202-2733
214-665-7457
Fax:214-665-7446
David Cozad
Office of Regional Counsel
U.S. Environmental Protection Agency
726 Minnesota Avenue (CNSL)
Kansas City, KS 66101
913-551-7587
Fax: 9 i 3-551 -7467
David Cozzie
Regulatory Impact Analyst
Economics, Methods,
and Risk Assessment Division
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-0479
Fax:703-308-0511
Lynn Dail
Environmental Scientist
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-U)
Dallas, TX 75202-2733
214-665-2234
Fax: 214-665-7263
Becky Daiss
Environmental Protection Specialist
Economics, Methods,
and Risk Assessment Division
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-0506
Fax: 703-308-0511
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Allyn M. Davis
Aaing Deputy Regional Administrator
U.S. Environmental Protection Agency
1445 Ross Avenue (6RA-D)
Dallas, TX 75202-2733
214-665-2100
Fax: 214-665-6648
Kerry Dearfieid
Biologist
Science Policy Staff Council
U.S. Environmental Protection Agency
401 M Street, SW (850 f)
Washington, DC 20460
202-260-4752
Fax: 202-260-0744
E-mail: dearfield.kerry@epamail.epa.2ov
Phil Dellinger
Project Manager
Source Water Protection Branch
Ground Water/UIC Section
Super-fund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6WQ-SG)
Dallas, TX 75202-2733
214-665-7142
Fax: 2(4-665-6689
Steve Eliers
Team Leader
Center for Combustion Science and Engineering
OK/TX Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-O)
Dallas, TX 75202-2733
214-665-8312
Fax: 214-665-2164
Bobbie Erlwein
Regional Representative
Agency for Toxic Substances
and Disease Registry
1445 Ross Avenue (SF-LN)
Dallas, TX 75202-2733
214-665-8360
Fax:214-665-2237
E-mail: eriwein.roberta@epamail.epa.gov
Penelope Fenner-Crisp
Deputy Director
Office of Pesticide Programs
U.S. Environmental Protection Agency
401 M Street, SW (7509C)
Washington, DC 20460
703-305-7092
Gerald Fontenot
Associate Director
Compliance Assurance and
Enforcement Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-X)
Dallas, TX 75202-2733
214-665-8150
Fax: 214-665-7446
|ack Fowle
Science Advisory Board
Office of the Administrator
U.S. Environmental Protection Agency
401 M Street, SW (1400F)
Washington, DC 20460
202-260-8325
Fax: 202-260-7118
Bill Gallagher
OK/TX Section Manager
Compliance Assurance
and Enforcement Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-0)
Dallas, TX 75202-2733
214-665-2210
Fax: 214-665-7446
Camille Haeni
Remedial Project Manager
Multimedia Planning and Permitting Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-N)
Dallas, TX 75202-2733
214-665-2231
Fax: 214-665-6762
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Rosemary Henderson
EPCRA Coordinator
Superfund Division
Response and Prevention Branch
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-RP)
Dallas, TX 75202-2733
214-665-2293
Fax: 214-665-7447
Diana Hinds
Enforcement Coordinator, FIFRA
FIFRA Enforcement
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-P)
Dallas, TX 75202-2733
214-665-7561
Fax: 214-665-2164
Bill Honker
AR/OK/TX Branch Chief
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-A)
Dallas, TX 75202-2733
214-665-6670
Fax: 214-665-6660
Mike Jansky
Environmental Engineer
Office of Planning and Coordination
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-XP)
Dallas, TX 75202-2733
214-665-7451
Fax: 214-665-7446
Woodruff (Barnes) Johnson
Director
Economics, Methods,
and Risk Assessment Division
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-8881
Fax:703-308-0311
Myron Knudson
Director
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF)
Dallas, TX 75202-2733
214-665-6701
Fax: 214-665-7330
Ghassan Khoury
Toxicologist
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-L)
Dallas, TX 75202-2733
214-665-8515
Fax: 214-665-6660
Youngmoo Kim
Toxicologist
Hazardous Waste Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-0)
Dallas, TX 75202-2733
214-665-6788
Fax: 214-665-6762
E-mail: kim.youngmoo@epamzul.epa.gov
Stephen Kroner
Environmental Scientist
Economics, Methods,
and Risk Assessment Division
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-0468
Fax:703-308-0511
Steve Luftig
Director
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
401 M Street, SW (5201G)
Washington, DC 20460
703-603-8960
Fax:703-603-9146
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Suzanne Marcy
Senior Scientist for Ecology
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8601)
Washington, DC 20460
202-260-0689
Fax: 202-260-0393
E-mail: marcy.suzanne@epamail.epa.gov
Alec McBride
Economics, Methods,
and Risk Assessment Division
Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW (5307W)
Washington, DC 20460
703-308-0466
Fax:703-308-0511
E-mail: mcbride.alec@epamail.epa.gov
Mary McCarthy-O'Reilly
Program Analyst
Science Policy Council Staff
Office of Research and Development
U.S. Environmental Protection Agency
Office of Research and Development
401 M Street, SW (8103)
Washington, DC 20460
202-260-4461
Fax: 202-260-0744
Bruce Means
Senior Process Manager for Response Decisions
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
401 M Street, SW (5202G)
Washington, DC 20460
703-603-8815
Fax:703-603-9133
Michael Morton
Toxicologist
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-O)
Dallas, TX 75202-2733
214-665-8329
E-mail: monon.mich2el@epamail.epa.gov
Beverly Negri
Superfund Administrative Reforms Coordinator
EPA Brownfields Liaison/Dallas
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF)
Dallas, TX 75202-2733
214-665-8157
Fax: 214-665-6660
Edward Ohanian
Technical Advisor
Health and Ecological Criteria Division
Office of Science and Technology
Office of Water
U.S. Environmental Protection Agency
401 M Street, SW (4304)
Washington, DC 20460
202-260-7571
Fax: 202-260-1036
Steve Ostrodka
Chief, Technical Support Section
Superfund Division
U.S. Environmental Protection Agency
77 West Jackson Boulevard (SRT-4J)
Chicago, IL 60604
312-886-3011
Fax:312-353-9281
Sharon Parrish
Chief, Watershed Management Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6WQ-EW)
Dallas, TX 75202-2733
214-665-2210
Fax: 214-665-7446
Dorothy Patton
Acting Director
Office of Research and Science Integration
Office of Research and Development
U.S. Environmental Protection Agency
401 M Street, SW (8104)
Washington, DC 20460
202-260-7669
Fax:202-260-0106
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I.J. Payne
Toxicologist
Hazardous Waste Enforcement Division
Technical Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-HX)
Dallas, TX 75202-2733
214-665-8322
Fax: 214-665-7446
Neil Pflum
Environmental Engineer
Source Water Protection Branch
U.S. Environmental Protection Agency
1445 Ross Avenue (6WQ-SP)
Dallas, TX 75202-2733
214-665-2295
Gerald Phillips
Corrective Action Manager
Waste, Pesticides, and Toxics Division
U.S. Environmental Protection Agency
77 West Jackson Boulevard (D-8J)
Chicago, IL 60606
312-886-7435
Fax:312-353-4788
Jon Rauscher
Toxicologist
Superfund Division
U.S. Environmental Protection Agency
(445 Ross Avenue (6SF-L)
Dallas, TX 75202-2733
214-665-6775
Fax: 214-665-6762
Larry G. Reed
Deputy Director
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
1235 Jefferson Davis Highway - Suite 902
(5201 G)
Arlington, VA 22202
703-603-8960
Fax: 703-603-9146
Susan Roddy
Environmental Scientist
Superfund Division
U,S. Environmental Protection Agency
1445 Ross Avenue (6SF-L)
Dallas, TX 75202-2733
214-665-8518
Joseph Schultes
Environmental Engineer
Enforcement/Hazardous Waste
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-HS)
Dallas, TX 75202-2733
214-665-2244
Fax: 214-655-7446
E-mail: schultes.joseph@epamail.epa.gov
Paul Sieminski
Environmental Engineer
Multimedia Planning and Permitting Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-A)
Dallas, TX 75202-2733
214-665-8503
Fax: 214-665-6762
Margaret Stasikowski
Director
Health and Ecological Criteria Division
Office of Science and Technology
Office of Water
U.S. Environmental Protection Agency
401 M Street, SW (4304)
Washington, DC 20460
202-260-5391
Fax: 202-260-1036
Bob Sturdivant
Facility Manager
Multimedia Planning and Permitting Division
New Mexico/Federal Facilities Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-N)
Dallas, TX 75202-2733
214-665-7440
Fax:214-665-7263
joe Swick, Jr.
Environmental Protection Specialist
Office of Planning and Coordination
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-XP)
Dallas, TX 75202-2733
214-665-7456
Fax:214-665-7446
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Cecilia Tapia
Chief
Site Assessment Cost Recovery Program
Superfund Division
U.S. Environmental Protection Agency
726 Minnesota Avenue (SUPR)
Kansas City, KS 66101
913-551-7733
Fax:913-551-7063
E-mail: tapia.cecilia@epamail.epa.gov
Chris Villarreai
Project Manager
AK/OK/TX Branch
Texas Section
Superfund Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6SF-AT)
Dallas, TX 75202-2733
214-665-6758
Fax: 214-665-6660
David Yogler
Geologist
Multimedia Planning and Permitting Division
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-O)
Dallas, TX 75202-2733
214-665-7428
David Weeks
Team Leader
Center for Combustion Science and Engineering
OK/TX Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-O)
Dallas, TX 75202-2733
214-665-6768
Fax: 214-665-2164
Bob Wilkinson
Environmental Scientist
Hazardous Waste Enforcement Branch
Technical Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6EN-HX)
Dallas, TX 75202-2733
214-665-8316
Fax: 214-665-7446
Jeffrey Yurk
Toxicologist
Multimedia Planning and Permitting Division
OK/TX RCRA Permits Section
U.S. Environmental Protection Agency
1445 Ross Avenue (6PD-OI445)
Dallas, TX 75202-2733
214-665-8513
Fax: 214-665-6660
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, DISTRIBUTE, OR QUOTE.
APPENDIX C
CUMULATIVE RISK ASSESSMENT PLANNING AND SCOPING HANDOUTS
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July 10, 1996
Cumulative Risk Background
The attached material provides an introduction to the cumulative risk process. The
Science Policy Council is developing a framework for planning and scoping cumulative risk
assessments which promotes a risk analysis dialogue among the risk assessor, risk manager,
economist, and other technical advisors about the purpose, scope and technical approach for
conducting the risk assessment. One part of the scope depends on the kinds of data are available
on the aspects of risk considered in the assessment. The SPC believes that we must first identify
the range of possible elements that could be considered and then document what we actually
decide to consider in a risk assessment. The attached materials are intended to help you engage in
such a scoping exercise. We hope that you find this material useful and informative and we invite
your comments and questions.
1. "Cumulative Risk and the Risk Characterization Colloquium" provides some definitions and an
overview of cumulative risk-READ THIS FIRST.
2. " Appendix 1. Outline of Risk Dimensions and Elements" can serve as a checklist for noting in
retrospect what a case study covered and what other areas it should include if it were done in the
future.
3. "Cumulative Risk Assessment Matrix for Triazmes" is an example of this type of analysis
developed by members of the SPC writing group for a pesticide review of Triazines. On the last
page, they discuss what they learned.
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1. Cumulative Risk and the Risk Characterization Colloquia
Cumulative risk assessment (CR) is the process for evaluating the aggregate potential for
adverse effects from one or more stressors on a defined populations). In the risk characterization
colloquia, CR discussions will focus on the first step— planning and scoping. Planning and
Scoping is a formal process or dialogue for discussing the purpose, scope, and technical approach
for the risk assessment. During this Risk Analysis Dialogue, the risk manager, risk assessor,
economist, and other technical advisors discuss management objectives, risk management
alternatives, resources available for the assessment and the context for the risk assessment. In
some instances, (such as negotiated rule making, comparative risk projects, or for some
community based risk assessment) interested and affected parties may participate directly hi the
planning process. Planning and scoping are not unique to CR, however, the plans are often
incomplete and do not reflect an agreement between the assessor and manager about the scope or
approach for the assessment; Planning and Scoping should lay the foundation for addressing the
questions that the manager will ask in the risk characterization. Information from the planning
process is used by the risk assessor for problem formulation.
Problem Formulation (as described in the ecological risk assessment guidelines) is used
for generating and evaluating preliminary hypotheses about why health or ecological effects have
occurred, or may occur from environmental stressors selecting assessment endpoints, and
developing a analytical plan for conducting an environmental risk assessment The case study on
Waquiot Bay will focus extensively on the problem formulation step.
At the colloquia, an overview of the cumulative risk analysis dialogue will be presented in
the plenary session. In breakout sessions, participants will engage in a retrospective planning and
scoping exercise to discuss the purpose and scope of the risk assessment for management
purposes and identify aspects of cumulative risk that could have been addressed for the case
study. An example of a completed matrix for Triazines is attached. On the second day, highlights
will be discussed on the second day with upper management to identify the possible benefits of
addressing more factors in the risk assessments and some of the current barriers (both regulatory
and procedural).
As a participant, you should review the cumulative risk outline (which is attached
Appendix I) before the breakout session and during the session, ask questions of the facilitator or
case presenter. After the breakout session, write down suggestions or areas where you feel
guidance is needed or where the outline could be expanded. Consider how you feel about the
differences between the actual and possible scope of the case example risk assessment How
would this knowledge change the scope and approach to the risk assessment?
During the Risk Analysis Dialogue the risk assessor and risk manager define tile general
parameters of the assessment: its purpose, the context of the risk, data and resource availability,
potential risk management options, timing, scope, and how risks will be aggregated. Although
some elements of this process are already used by many program offices, the process is not
clearly defined and the critical decisions ace rarefy documented. In addition, the scope of the risk
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assessment is usually restricted to those covered by program statutory authorities.
For CR, problem formulation must distinguish between the range of possible assessment
parameters and those that the Agency will address and the relative emphasis on inherent technical
or socioeconomic factors which may affect the risk to certain groups or in certain locations. The
steps in the risk analysis dialogue are discussed below.
Identify the purpose. The purpose of the cumulative risk assessment is to aggregate the
effects of one or more stressors on a defined population. The scope of the assessment will be
influenced by the risk management goals or objectives — which are based on underlying values—
i.e., the outcomes desired. Goals may range from elimination to partial mitigation of the problem.
In some cases the goals may be competing, so that some negotiation must occur. The risk
assessor should select assessment endpoints and analyses to address these goals/objectives.
Discuss the questions that should be addressed in the Risk Analysis Dialogue. The risk
assessor should identify the context of the risk and develop a Matrix fin outline form) of
Cumulative Risk Possibilities. The risk assessor should identify data requirements, their priority,
and parties (both inside and outside the Agency) that should contribute information and
participate in the assessment The risk assessor should include data for hazard identification and
dose-response assessment. The risk assessor should discuss methods, data, and models available
to quantify and aggregate these risks. The risk manager and the assessor should identify which
compartments of the matrix will be addressed and document a rationale for those that are
excluded. Finally, they should develop a plan to explain how risks will be integrated, combined, or
weighted for the assessment
Risk Management Applications of the Risk Analysis Plan. Once the planning and scoping
has been completed, the risk assessor can identify peer review and outreach needs. The risk
manager can estimate time and resource requirements and identify potential risk management
options. The risk manager may consult with economists for any cost benefit analysis or with
engineers and other technical staff for the risk management decision. The risk manager has a
clear indication of what is expected and should be able to recognize when management needs to
be consulted because of unforeseen developments or data deficiencies.
Products from the Problem Formulation. The products of the problem formulation
should include a set of assessment endpoints that address management goals, a matrix of
cumulative risk assessment factors, conceptual models and assumptions that describe key
relationships among the stressor(s) and the assessment endpoints, and a plan for analysis of the
data.
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2. Appendix 1. An Outline of
This is a outline is intended to help risk managers and risk assessors discuss
the technical dimensions and specific elements that might apply to a particular risk
assessment. This outline can be used as checklist to note how die risk analysis will
be framed in terms of the sources, stressors, pathways, population, endpoints, and
time frames. The outline can also be used to plan the risk analysis with the risk
manager and explain the scope of the risk analysis to the interested and affected
parties. The next step is the technical approach (also called problem formulation in
the draft ecological risk assessment guidelines), a process in which the analysis
plan and preliminary hypotheses about the relationship between stressors and
effects on populations are developed in a conceptual model This model may be peer
reviewed.
For die purposes of this outline, six dimensions are used: sources, stressors,
pathways, population, endpoints, and time frames. Each dimension is defined
below by a question and some of the most likely answers are listed as elements for
the risk analysis.
Dimension A. Population
( "Who /What/Where is at Risk?1)
1. Humans
a. Individual
b. General population distribution or estimation of central tendency and
high end
c. Population subgroups
1. Highly exposed subgroup (geographic area, age group,
race/ethnic group, economic status)
2. Highly sensitive subgroups (asthmatics or other pre-existing
conditions, age)
3. Geographical
2. Ecological Entities
a. Groups of individuals
b. Populations
c. Multiple species
d. Habitats/ecosystems
3. Landscape or Geographic Concerns
a. Ground water aquifers
b. Watersheds (surface water bodies)
c. Airsheds
dL Regional ecosystems
e. Recreational 1«p^«
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Dimension B. Sources
(What are the Relevant Sources of Stressors?)
1. single source
a. point sources (industrial/commercial discharge, superfund sites)
b. non-point sources (automobiles, agriculture, consumer use
releases)
c. natural sources (flooding, hurricanes, earthquakes, forest fires)
2. Multi-sources (Combinations of those above)
Dimension C. Stressors (What are the Stressors of Concern?)
1. Chemical(s)
a. Single chemical
b. Structurally related class of substances
c. Structurally unrelated substances with g»»ilar mechanism of
impact and/or same target organ
d. Mixtures (itiMimijar structures/dissimilar mechanisms)
2. Radiation
3. Microbiological/biological (range from morbidity to ecosystem disruption)
4. Nutritional status (diet, fitness, or metabolic state)
5. Economic (such as access to health care)
6. Psychological (knowledge of living near uncertain risks)
7. Habitat Alteration (urbanization, hydrologk modification, timber harvest)
8. Land-use changes (agriculture to residential, public to private recreational uses)
9. Global climate change
10. Natural Disasters (Roods, hurricanes, earthquakes)
Dimension P. Pathways
(Environmental Pathways and Routes of Exposure. "What are the Relevant
Exposures?")
1. Pathways (one or more may be involved)
a. Air
b. Surface Water
c. Groundwater
d. Soil
e. Solid Waste
2. Routes of Human and single species exposures
a. Ingestion (both food and water)
b. Dermal (includes absorption and uptake by plants)
c. Inhalation (includes gaseous exchange)
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d. Non-dietary ingestion ("hand-to-mouth" behavior)
3. Routes of Exposure within communities and ecosystems
a. Bioaccumulation
b. Biomagnification
c. Vector transfers (parasites, mosquitoes)
Dimension E. Endpoints
(What are the assessment endpoints?)
1. Human Health (Based on animal studies, morbidity and disease registries,
laboratory and clinical studies, and/or epidemiological studies or data)
a. Cancer
b. Neurotoxicological
c. Reproductive dysfunction
d. Developmental
e. Cardio-vascular
f. Immunological
g. Others
2. Ecological Effects (These may be acute, chronic,
a. Population or Species
1) Loss of fecundity
2) Reduced rate of growth
3) Acute or Chronic toxicity
4) Change in biomass
b. Community
1) Loss of species diversity
2) Introduction of an exotic species
3) Loss of keystone species
c. Ecosystem
1) Loss of a function (photosynthesis, mineral metabolism)
2) Loss of habitat structure
3) Loss of a functional group of organisms (grazers, detritivores)
4) Climate change (sunlight, temperature change)
5) Loss of landscape features (migration corridors, home ranges)
Dimension F. Time frames
(What are the Relevant Time Frames: Frequency, Duration, Intensity and Overlap
of Exposure Intervals for Mixtures of Stressors)?
1. acute
2. subchronic
3. chronic or effects with a long latency period
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3. Cumulative Risk Assessment Matrix for Triazines
(Possible and Actual Factors Considered)
This matrix represents an attempt to the reconstruct the problem
formulation conducted to develop a cumulative risk assessment for three triazine
pesticides (Atrazine.Simazine and Cyanazine). The matrix was developed by the
Cumulative Risk Writing Group, not the Office of Pesticide Programs (OPP), but
attempts to capture, retrospectively, the decision logic OPP applied after it
determined that an unreasonable risk may exist as a consequence of the use of
these three chemicals in agricultural and other settings. (OPP, in fact, did not
carry out this formal a problem definition process when planning this risk
assessment). The Writing Group attempted to develop the matrix in the context of
the proposed Cumulative Risk Factors Matrix (see Appendix I).
Atrazine, Simazine and Cyanazine are herbicides often used in combination
with other pesticides, including with each other or as alternatives to one another, in
some cases.
These three herbicides are not the only members of the triazine class.
However, they were analyzed together as a subclass (the chloro-s-triazines) because
they a) are structurally-related, b) degrade or metabolize to similar
degradates/metabolites and, c) exhibit the same toxitity endpoint of concern
(mammary cancer in female Sprague-Dawley rats) which is believed to develop via
die same mode (mechanism) of action. Cancer is one of the "triggers* in the Federal
Insecticide, Fungicide and Rodenticide Act (FIFRA) that allows the Agency to
reexamine the eligibility for continued registration of some or all uses, of a pesticide.
In the original scoping of the assessment, timing and resources limited the focus
and activity to the human health concern. The Program also believes that the
potential for adverse ecological effects exists, and will pursue that concern in the
future.
The factors identified in bold were included in the risk assessment that
became the basis for the Position Document 1-Initiation of Special Review
(November 1994).
Dimension A. Sources (What are the relevant sources of
stressors?)
1. Single source
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2. Multiple sources
a. Manufacture
(1) Workers and workplace (covered by OSHA)
(2) Releases from plant (to be covered by TRJ)
(3) Waste stream controls (NPDES,RCRA,etc.)
b. M/L/A (Mixer/Loader/Applicator; relates to farmer/grower,
homeowner or commercial applicator)
c. Imports
(1) Residues on imported agricultural products
(2) Transboundary drift
d. Export (largely unregulated)
e. Household use (i.e. lawn care)
f. Natural sources (flooding, hurricanes, earthquakes) causing
redistribution
Dimension B. Stressors (What are the stressors of concern?)
1. Chemical(s)
a. Single chemical
b. Structurally related class of substances
c. Structurally unrelated substances with similar mechanism of impact and/or
same target organ
d. Mixtures (dissimilar structures/dissimilar mechanisms)
2. Radiation
3. Microbiological/biological (range from morbidity to ecosystem
disruption)
4. Nutritional status (diet, fitness, or metabolic state)
5. Economic (such as access to health care)
6. Psychological (knowledge of living near uncertain risks)
7. Habitat Alteration (urbanization, hydrologk modification, timber
harvest)
8. Land-use changes (agriculture to residential, public to private
recreational uses)
9. Global climate change
10. Natural Disasters (Floods, hurricanes, earthquakes)
Dimension C. Pathways (Environmental Pathways and Routes of
Exposure-"What are the relevant Exposures?"
1. Pathway(s) and routes of exposure to humans
a. Manufacture and formulation of products
(1) Pathways
(a) Surface water
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(b) Air
(c) Solid waste
(d) groundwater
(e) Soil
(f) Indoor
(2) Routes of exposure
(a) Inhalation
(b) Dermal
(c) Ingestion (secondary to initial inhalation or dermal
contact)
b. M/UA
(1) Pathway: Direct contact with applied material
(2) Route of exposure-Dermal
c. Post-application exposure
(1) Ag. reentry
(a) Pathway-Direct contact with applied material
(b) Route(s) of exposure-Dermal, inhaiation and indirect
ingestion
(2) Residential (homeowner)
(a) Pathway-Direct contact with applied material
(b) Route(s) of exposure-Dermal, inhalation and indirect
ingestion
(3) Food (Including water sources)
(a) Pathway(s)-Residues in food, surface and
groundwater
(b) Route(s) of exposure-dermal and
direct/indirect ingestion
3. Routes of Exposure within communities and ecosystems
a. Bioaccumulation
b. Biomagnificationi
c. Vector transfers
Dimension D. Population ("Who/What/Where is at risk?")
1. Humans
a. Individual
(1) Manufacture and formulation
(a) Workers
(b) Workers' families
(c) Community members near site
(2) M/UA
(a) Workers-categorized by age,sex,reproductive
status
(b) Workers' families
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(3) Post-application Exposure
(a) Ag. Reentry
(b) Residential
(c) Food (including water)
b. General population distribution and estimation of
central tendency and high end
(1) Manufacture and formulation
(a) Workers
(b) Workers' families
(c) Community members near site
(2) M/UA
(a) Workers-categorized by age, sex, re productive
status
(b) Workers' families
(3) Post-application Exposure
(a) Ag. Reentry
(b) Residential
(c) Food (including water)-exposure assessment
assumed average food consumption/residue
values, but drinking water at the MCL {I.e.
high end)
c. Population subgroups
(1) Highly exposed subgroup (e.g. occupational,
geographic)
(a) Manufacture and formulation
(i) Workers
(ii) Workers' families
(Hi) Community members near site
(b)M/UA
(!) Workers-categorized by
age,sex,reproductive status
(ii) Workers' families
(c) Post-application Exposure
(i) Ag. Reentry
(ii) Residential
(iii) Food (including water)-exposure
assessment assumed average food
consumption/residue values, but drinking
water at the MCL (i.e.high end)
(2) Highly sensitive subgroup (no consensus as to whether infants
and children should be considered 'highly sensitive"; nonetheless, the dietary
c-io
-------
risk assessment evaluated exposure/risk to 22 subgroups as well as the general
population)
(3) GeographicaHHigher dietary risk estimated in areas with high
agricultural use, e.g. Midwest com belt)
2. Ecological Entities-(Future)
a. Groups of individuals
b. Populations
c. Multiple species
d. Habitats/ecosystems
3. Landscape or Geographic Concerns
a. Groundwater aquifers
b. Watersheds (surface water bodies)
c. Airsheds
Dimension E. Endpoints (What are the assessment endpoints?)
1. Human Health
a. Cancer (this endpoint "drove" the risk assessment)
b. Cardiotoxicity (Questions resolved for atrazine;endpoint considered
•covered" by cancer risk assessment)
c. Reproductive/developmental toxicity
e. Neurotoxicity
f. Immunotoxicity
g. Other systemic toxicity
2. Ecological Effects (These may be acute, cnronic.or subchronic)
a. Population or Species
1) Loss of fecundity
2) Reduced rate of growth
3) Acute or Chronic toxicity
4) Change in biomass
b. Community
1) Loss of species diversity
2) Introduction of an exotic species
3) Loss of keystone species
c. Ecosystem
1) Loss of a function (photosynthesis, mineral metabolism)
2) Loss of habitat structure
3) Loss of a functional group of organisms (grazers, detritivores,)
4) Climate change (sunlight, temperature change)
5) Loss of landscape features (migration corridors, home ranges,
C-ll
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Dimension F. Timeframes ("What are the relevant timeframes" Frequency,
Duration, Intensity and Overlap of Exposure Intervals for Mixtures of Stressors?")
1. Acute
2. Subchronic (including intermittent)
3. Chronic or effects with long latency period (including
intermittent)
Lessons Learned
The most obvious lesson learned is that the exercise of problem formulation
should be carried before the risk assessment is started.
Also, it was very dear, even during this very cursory attempt to reconstruct the
decision logic, that additional sources of exposure could, and, perhaps, should have
been considered in developing the risk assessment Generally, however, experience
tells us that occupational exposure related to mixing/loading/applying pesticide
products presents the greatest potential for risk. In this case, the risk assessment
covers the domain of more than one Program office (OPP and OW), showing that
inadvertent contamination of drinking water supplies may be a major risk factor, at least
for a significant subset of the U.S. population. This circumstance offers the possibility of
identifying risk reduction measures under more than one legislative mandate.
Lastly, the existing risk assessment is limited to the evaluation of human health
concerns. Not completely transparent in the exercise described above is the decision
that time, resources and the existing data were not available to go forward with an
assessment of ecological effects at the same time as the assessment of human health
risk.' A good problem formulation would include a systematic evaluation of all factors,
and a full documentation of the decisions to include/exclude certain of those factors.
C-12
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Cumulative Risk Project
9
Sponsored by the Science Policy
Council
-------
o
Rationale for Projec
/. Consider Total Environmental Risks
2. Develop CR Concept Beyond
"Multiple-Multiples "
3. Improve Risk Assessor/Manager
Communication
4. Explain Agency Role to Public
- Define risks within EPA authority
- Discuss other risk management options
-------
Definition of Cumulative Risk
"Risks from one or more stressors
considered in aggregate"
Each Assessment is case-specific
s • Who is affected or stressed?
• What are the stressors?
• What are the sources?
• What are the pathways?
• What is the time frame for the risk?
• What are the assessment endpoints?
-------
p
K-»
o\
Risk Assessment/ Management Decision Process
New Management Needs
Planning
and
Scoping
(Assessor-
Manager
Dialogue)
L
j
Risk Assessment
f U-**^1*.**, I yh*^% x
Formulation
Risk Analysis
haracterization/
Economic, Poli-Science,
and Social Analysis
-------
o
Cumulative Risk Objective
the Colloquium
Develop a Scope and Plan for the Case
Studies
Brainstorm a list of Possible Risk
Dimensions and Elements
Identify needs and concerns for the assessor
and manager based on the Case Studies
Discuss the implications for assessors
-------
Planning and Scoping Define Our
Itinerary
n
t—*
oo
What can and will we
address?
Risk Assessor-Risk
Manager Dialog
Preparation for a risk
assessment
-------
What does a Manager want to
know before you start?
n
Scope of the Risk
What data are needed?
What data are
available?
Who can help?
Schedule-Cost
Knowledge gaps
Public concerns
-------
Planning and Scopi
o Identify the Purpose
® Develop a matrix of possibilities
© Determine what questions should be
addressed
o Define the actual risk matrix
© Develop an approach
-------
Planning and Scopin
Risk Assessor/Manager Define Scope
• Management Goals and Values
2 • ID context of the Risk
t—i
• Discuss questions to be answered
• Estimate resource, data and time
requirements
• Identify participants (Agency and Beyond)
-------
Assessor-Manag§
Dialog
Risk Assessor
1. Background Knowledge
a. scale of the risk
b. critical endpoints
2. Available/appropriate
data (where?)
3. CR Matrix
4. Gaps
5. Potential RM options
Stakeholders
l.Values
2. Impacts
Risk Manager
1. Why is RA needed?
2. Management goals
3. Policy concerns
4. Political concerns
5. Timing/Resources
6. Acceptable Levels of
uncertainty?
7. Potential RM options
Economists
1. Affected Groups
2. Equity of Impact
Problem Formulation
C-22
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Risk Dimensions and Elements
0
to
Prepare an Outline of Possibilities
What can and will we address?
Preparation for a risk assessment
-------
Cumulative Risk Dimensions
Population
Pathways
-------
Cumulative Effects Elements of
Risk
8
-------
2
o\
-------
tsi
Objectives of Planning and
Scoping the Assessment
o Achieve desired management outcome
Match assessment endpoints to goal
Document Basis for Risk
Characterization
-------
Limitations in Current P
oo
Scope often Confined by Statute^
Generally Assumes Risks are Additive
Unregulated Source contribution often
overlooked
Cost-data intensive; may be expensive
• Collaboration and problem definition can
reduce costs significantly
-------
DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
APPENDIX D
CASE PRESENTERS, CHAIRS, AND FACILITATORS
-------
xvEPA
United States
Environmental Protection Agency
Science Policy Council
Risk Characterization Colloquium
Series C2: OSWER and EPA Regions
Le Meridien Hotel
Dallas, JX
August 1-2, 1996
Breakout Session Chairs. Case Presenters, and Facilitators
Case Study A: Lavaca Bay (OERR and Region 6)
Session Chair: Dave Bennett
Facilitator: Ruth Bleyler
Case Presenter: Jon Rauscher
Case Study B: Midlothian (Region 6)
Session Chairs: Gerald Carney and Cecilia Tapia
Facilitator: Ed Onom'on
Cose Presenter: Jeffrey Yurk
Case Study C: RCRA Biocrude (OSW)
Session Chairs: Larry Reed and Bill Gallagher
Facilitator: Jack Fowle
Cose Presenters: Becky Daiss and Dave Cozzie
Case Study D: Waquoit Bay Watershed (OW and Region I)
Session Chairs: Margaret Stasikowski and Sharon Parrish
Facilitator: Kerry Dearfield
Case Presenters: Suzanne Mercy
Risk Managers Panel Members
Steve Luftig, OSWER/OERR
David Cozad. Region 7
Myron Knudson, Region 6
Gerald Phillips, Region 5
Br/l Honker, Region 6
i Printed on Recycled Paper
D-l
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DO NOT QUOTE OR CITE
DRAFT
OFFICE OF WATER
RISK CHARACTERIZATION POLICY
IMPLEMENTATION STATEMENT
Internal Review Document
For
Risk Characterization Colloquium
November 1995
Note: This draft will be revised at the completion of EPA
CoIIoquia, Roundtables, and Plenary Session on
Risk Characterization.
F-71
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TABLE OF CONTENTS
I. Purpose 1
n. Background 2
IIL Legal Effect 4
IV. Scope . 4
V. Relationship of risk characterization
to risk assessment and risk communication 7
VI. Criteria for judging adequacy of risk characterizations 8
A. Clarity 8
B. Transparency - 9
C. Reasonableness 10
VH. Ensuring consistency 10
VHI.Evahiating Office of Water circumstances , 12
IX. Points to consider when preparing risk characterizations and criteria for
evaluating compliance with the Risk Characterization Policy 13
A. Summary of and confidence in the major risk conclusions 14
B. Summary of key issues 15
C. Methods used 16
D. Summary of the overall strengths and uncertainties
of the risk assessment 17
E. Put this risk assessment in context with
other similar risks 19
F. Other information 20
G. Mechanisms to evaluate risk characterization 21
X. Statement of Commitment 22
XL Attachments (1, 2, 3, 4, and 5)
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I. Purpose
This Risk Characterization Polocy Implementation Statement provides the
operational framework within which all risk characterizations in the Office of
Water (OW) are developed The Guidelines expand on me March 1995 Risk
Characterization Policy (Attachments 1 to 4) and its accompanying Guidance
(Attachment 5) by providing OW-specific factors which affect the
implementation of the general policy.
The Implementation Guidelines identity the kinds of assessments produced
by OW which are covered by me Risk Characterization Policy, and addresses
how the principles and guidance will be reflected in each of mem. Where
significant principle or guidance points cannot be incorporated, these guidelines
call on producers of risk characterizations to provide reasons for such gaps.
The objective of the Risk Characterization Policy and this Implementation
Guidelines document is to ensure mat risk characterizations produced by this
Program form a coherent picture at a level of detail appropriate for the decision
being supported. Accordingly, greater emphasis is placed on ensuring clarity,
consistency, and reasonableness of the risk picture and transparency of the risk
assessment process as an input to the decision-making process man on
reformatting or otherwise reiterating the conclusions of risk assessment
components that precede the characterization.
EPA is developing policies and procedures for several key issues that cut
across the Agency (e.g., uncertainty analysis, updating IRIS and supplementing
IRIS with risk characterization language in the interim, etc.). As they are
developed they will become part of OWs policy and update this document.
II. Background
In March 1995, the Administrator issued, a policy statement (Attachment
1) requiring that risk characterizations be prepared "in a manner that is clear,
transparent, reasonable and consistent with other risk characterizations of similar
scope prepared across programs in the Agency."
The "Guidance for Risk Characterization", (Attachment 5) which
accompanies the Policy Statement, provides general principles for characterizing
risk. These principles are as follows.
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1. The risk characterization integrates the information from the
hazard identification, dose-response, and exposure
assessments, using a combination of qualitative information,
quantitative information, and infbnnation about uncertainties.
2. The risk characterization includes a discussion of
uncertainty and variability.
3. Well-balanced risk characterizations present risk conclusions
and information regarding the strengths and limitations of
the assessment at the level appropriate for the risk
assessment
Also identified in the "Policy for Risk Characterization" are the following key
aspects of risk characterizations:
1. Risk assessments should be transparent, in that the conclusions
drawn from the science are identified separately from policy
judgments, and the use of default values or methods and the use of
assumptions in the risk assessment are clearly articulated.
2. Risk characterizations should include a summary of the key issues
and conclusions of each of the other components of the risk
assessment, as well as describe the likelihood of harm. The
summary should include a description of the overall strengths and
limitations (including uncertainties) of the assessment and
conclusions.
3. Risk characterizations should be consistent in general format, but
recognize the unique characteristics of each specific situation.
4. Risk characterizations should include, at least in a qualitative sense,
a discussion of how a specific risk and its context compare with
other similar risks. This may be accomplished by comparisons
with other chemicals or situations in which the Agency has decided
to act, or with other situations familiar to me public. The
discussion should highlight the limitations of such comparisons.
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5. Risk characterization is a key component of risk communication,
which is an interactive process involving exchange of information
and expert opinion among individuals, groups and institutions.
Risk assessments conducted by OW require different levels of effort They
should be viewed as a continuum, because more man one level of risk
assessment effort may be employed for many OW actions and activities. Risk
assessment activities conducted to support one level of effort may lead to a
different level of effort as the requirements for the assessment and its intended
uses change. The amount of time, effort and level of detail devoted to risk
characterization in OW should vary according the nature and magnitude of the
risk assessment
The following are representative complete risk assessments (which will
require the application of the Risk Characterization Policy) done in OW:
1. Human Risk Assessment:
• Drinking Water Maximum Contaminant Level Goals
• Ambient Water Quality Criteria
• Drinking Water Health Advisories
• National Guidance for Assessing Chemical Contaminants for Use in Fish
Consumption Advisories
• Assessment and Management of Contaminated Dredged Materials Containing
Contaminants that Bioaccumulater
" Regulations for Sewage Sludge (Biosolids) Use or Disposal
• Approval/Disapproval of State Water Quality Standards that vary from
EPA Water Quality Criteria.
2. Ecological Risk Assessment (contingent upon the development of Agency
Ecological Risk Assessment Guidelines and Program Specific Priorities):
• Ambient Water Quality Criteria (Aquatic Life)
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• Assessment and Management of Contaminated Dredged Materials Containing
Contaminants mat Bioaccumulate
• Regulations for Sewage Sludge (Biosolids) Use or Disposal
• Approval/Disapproval of State Water Quality Standards that vary from EPA
Water Quality Criteria
• Watershed Risk Assessment
• National Nutrient Enrichment Assessment Strategy
• Sediment Criteria (for Metals) and Sediment Assessment of Mixtures of
Contaminants
• National Bioaccomulation Assessment
• National Methodology for deriving Criteria to protect Wildlife
• Biological Criteria tor Estuarine and near Coastal Marine Waters and Lakes
and Reservoirs
• Whole Effluent Toxicity Criteria and Implementation Guidance
• Water Quality Standards for Wetlands Protection.
III. Legal Effect
This risk characterization policy implementation statement and associated
guidance on risk characterization do not establish or affect legal rights or
obligations. Rather, they confirm the importance of risk characterization as a
component of risk assessment, outline relevant principles, and identity factors
that staff from OW should consider as they implement mis policy.
This risk characterization policy implementation statement and associated
guidance do not stand alone; nor do they establish a binding norm that is finally
determinative of the issues addressed. Except where otherwise provided by law,
OW's decision on conducting a risk assessment in any particular case is within
OW's discretion. Variations in the application of this policy and associated
F-76
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guidance, therefore, are not a legitimate basis for delaying or complicating
action on OWs or Agency decisions.
IV. Scope
All risk characterizations prepared by OW in support of decision making
at EPA are covered by the Administrator's Risk Characterization Policy and this
implementation statement Discussion of risk in all OW-generated reports,
presentations, briefings, decision packages, and other documents should be-
substantively consistent with the policy and mis document
Risk assessment information is often filtered through several layers of
management before reaching the ultimate decision maker. In OW, reasons
should be given for-filtering out any risk characterization information during this
process.
It is OWs policy to require that each risk assessor prepares a risk
characterization for each risk assessment Each risk assessment prepared by or
for this Office should contain one or more sections on risk characterization at a
level of detail appropriate for the type of assessment The risk assessor will
clearly identity the scope of the assessment and the reason(s), if any, for not
considering certain factors outlined in the "Elements" document (Attachment 3)
accompanying the Administrator's Risk Characterization Policy. The guidance
to risk assessors, and the criteria by which they can be judged oh this point, are
that they:
A. Clearly define the scope of the assessment
1. Note, with a brief explanation, categories of hazard end points
(including ecotoxicity) that are specifically excluded from the
review.
2. Also note populations which are specifically excluded from review.
B. Clearly define the level of review used in this assessment
1. Give an idea of the types and quantity of data sources, reviews, and
databases that were utilized.
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8
2. If it is an extensive review, it is especially important to indicate all
major sources of information, and to highlight any major source not
utilized with the reasons why.
Documents that describe components of a risk assessment (e.g., stand
alone hazard or exposure assessments), even if prepared as separate documents,
will also follow the risk characterization policy in that they will strive for
clarity, transparency, consistency, and reasonableness.
Documents related to risk or any of its components which are submitted
to this Office by EPA contractors or other EPA Offices are expected to follow
the Risk Characterization Policy.
It is OWs policy mat documents from sources outside EPA that mis
Office uses in preparation of various risk assessments will be augmented by
adding risk characterization language to meet the requirements of the Risk
Characterization Policy.
It is OWs policy to clearly explain any circumstances where assessments,
and other infonnation such as IRIS, have been produced in the past by EPA but
which do not fully follow the risk characterization principles. Additional
guidance on how the use of IRIS and other information systems and documents
produced by ORD and others mat serve as inputs to OW generated risk
assessments will be developed by the Science Policy Council. This document
will be updated when such guidance is received.
Documents submitted by the public to this Office mat relate to risk
assessment or any of its components, including those that support alternatives to
EPA risk assessments, will be evaluated in light of the Risk Characterization
Policy and this guidelines document.
This Office will apply the general principles specified in the Risk
Characterization Policy to its assessments of ecological risk. Specifically, until
detailed Agency guidance becomes available, risk characterizations involving
ecological effects developed by this Program will strive to include a discussion
of the strengths and limitations of the assessment and will also strive to achieve
the Risk Characterization values of clarity, transparency, consistency, and
reasonableness.
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Assessments of benefits are not included in this Implementation
Guidelines. Although mis Office acknowledges that the principles of clarity,
transparency of process, consistency, and reasonableness apply also to analyses
of benefits, the Agency lias not yet developed guidance for these types of
assessments.
V. Relationship of risk characterization to risk assessment and risk
communication
As stated in the Risk Characterization Policy, "Risk Characterization is the
summarizing step of risk assessment The risk characterization integrates
information from the preceding components of the risk assessment" In other
words, risks can be partially described by the individual components of a risk
assessment, but risk-characterization is a conscious .and deliberate process of
bringing all important considerations about risk into an integrated picture. Even
more importantly, as an integrated picture, the risk characterization is not simply
a reiteration of conclusions of the various components, but a piece which
focusses on how those components interact
"Risk characterization11 is not synonymous with "risk communication.
The risk characterization policy addresses me interface between risk assessment
and risk management -Risk communication, in contrast, emphasizes the process
of exchanging information and opinion with the public. While the final risk
assessment document (including its risk characterization sections) is available to
the public, the risk communication process is better served by separate risk
information documents designed for particular audiences.
Therefore, this risk characterization guidelines document is written to
provide guidance to the risk assessor for his/her use in explaining the assessment
to risk managers. If this guidance is followed, the resultant risk
characterizations should also be understandable to an educated .and motivated
layperson.
VL Criteria for fudging adequacy of risk characterizations
The criteria for judging the extent to which OW risk characterizations
meet the Administrator's four values are summarized below and further
expanded in sections VII and IX of this document
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10
A. Clarity of risk characterizations will be judged by the extent to which:
1. Brevity is achieved and jargon is avoided;
2. The language and organization of the risk characterization are
understandable to EPA risk managers and the informed lay person;
3. The.purpose of the risk assessment is defined and explained (e.g.,
regulatory purpose, policy analysis, priority setting);
4. The level of effort (e.g., quick screen, extensive characterization)
put into the assessment is defined accompanied by the reason(s)
why mis level of effort was selected;
5. The strengths and limitations of the assessment can be understood
without needing to understand the technical details of the
assessment To the extent they are used, technical terms are
defined;
6. The scientific and policy bases, including biases (e.g. to err on the
side of safety), used in the assessment are dearly described;
7. Assumptions are defined and understandable explanations are given
for each policy decision made (e.g., use of default assumptions, use
of a linearized rather than threshold cancer risk model); and
8. Unusual issues specific to a particular risk assessment are fully
discussed and explained.
B. Transparency of the process used to characterize risk will be judged by
the extent to which:
1. Conclusions drawn from the science and technical information are
identified separately from policy judgments;
2. The characterizations incorporate the principles of the risk
characterization policy (e.g., the assumptions* are explained, the
strengths and imitations of the assessment and the uncertainties are
addressed in a balanced manner);
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11
3. The risk characterization does what it sets out to do in an
appropriate manner (e.g., it meets the expressed purpose, the level
of effort expended was appropriate for the decision made, all
relevant portions of the risk assessment paradigm were addressed);
C. The extent to which risk assessment conclusions and risk characterizations
are reasonable will be judged by whether.
1. They are determined to be reasonable by EPA risk managers and
the lay public;
2. All components are well integrated into an overall conclusion of
risk which is complete, informative and useful in decision-making;
3. They are based on the best available scientific information and
judgment, documenting sources appropriately;
4. They use common sense and portray me use of science and science
policy to assess risk in a forthright manner, acknowledging
scientific uncertainty;
VII. Ensuring Consistency
Consistency in definitions and methods of assessing risk is fundamental to
minimizing confusion about risk estimates generated across the Agency.
However, while risk assessments conducted in OW share similar goals with risk
assessments prepared by other parts of the Agency, statutory requirements and
regulatory interpretations influence OW risk assessment approaches. The
following sections describe areas where this Program can use Agency-wide
definitions, methods,,and risk descriptors to ensure consistency, and areas
where such use is constrained.
Some of the existing risk .assessment inconsistency in treating Group C
carcinogens within OW (Clean Water Act and Safe Drinking Water Act) and
across Agency programs (Office of Water, Office of Pesticides Programs, and
Office Research and Development) based on policy will -be harmonized as the
revised cancer guidelines become finalized. The differences in cancer risk
levels ranging from E-4 to E-6 are controlled by statutory
F-81
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12
requirements (i.e., Clean Water Act, Safe Drinking Water Act, Federal
Insecticide, Fungicide, and Rodenticide Act, etc.). For example, the Clean
Water Act is risk preventive statute, designed to control the risk from discharges
of pollutants into ambient water, the Safe Drinking Water Act is a
risk/feasibility statute designed to reduce levels of pollutants in drinking water at
the tap with the availability of appropriate treatment, analytical methods, and
cost in mind. In mis case, OW will ensure mat these statutory/policy
differences are explained in such a manner as to be understood by others in
EPA and by the general public.
The following procedures used by OW help to ensure that its risk
characterizations are consistent with characterizations produced by other parts of
the Agency. They also serve as criteria by which our success at ensuring
consistency can be*judged.
1. OW relies on Agency-wide guidelines, such as those for exposure
analyses and health risk assessment
2. OW uses Agency-wide information systems, such as the Integrated
Risk Information System (IRIS) and risk reference concentrations
(RfCs) which are produced by Agency-wide, consensus workgroups.
VIII. Evaluating Office-Specific Circumstances
The Risk Characterization Policy recognizes that "[tjhe nature of the risk
characterization will depend upon the information available, the regulatory
application of the risk information, and the resources (including time) available.11
Considerations specific to this Office which affect the degree to which risk
characterization can be accomplished include statutory requirements, court-
ordered deadlines, availability of data and/or information (e.g., lack of health
effects or exposure data, limited information on hazard identification and dose-
response contained in IRIS files, limited information on hazard identification,
dose-response, and/or exposure analysis for assessments that rely in part, or in
full, on analyses prepared by other Agencies or the private sector), and amount
of resources available to conduct the risk assessment and risk characterization.
OW conducts many types of risk assessments spanning the gamut from
site-specific, to source-category specific, to urban or regional area analyses, to
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nationwide or global assessments. ID general, the scope of the risk
characterization should reflect the information presented in the risk assessment
IX. Points To Consider When Preparing Risk Characterizations &
Criteria for Evaluating Compliance with the Risk Characterization
Policy
The Administrator's March 1995 Risk Characterization package provides a
list of elements to consider when assessing risk to human health (Attachment 3).
That list of elements will be used by this Office as the basic set of
considerations for each risk assessment and risk characterization that OW
performs, recognizing also, however, that there will be reasons for expanding or
contracting mat basic set of elements to fit the circumstances of a particular
case. In modifying me list of elements, this Office will clearly state in the risk
characterization the reasons for adding to or subtracting elements from that basic
list Such reasons may be written at a general level to cover several elements at
once, or may be written at a very specific, level to cover a specific element,
depending on the level of decision being supported.
The following discussion expands on the summarization and integration
aspects of risk characterization, as a supplement to Part H of the "Elements
Document" provided in the Administrator's package. The discussion is meant to
give farther explanation to risk assessors of the kinds of specific information
that may be relevant to this Office that will help decision-makers form a clear,
coherent, and integrated picture of risk at the level of detail appropriate for the
decision.
This section contains points to consider when characterizing risk. These
points focus on the principles and key aspects of risk characterization discussed
in Part II of the "Elements Document". When special circumstances (e.g., lack
of data, resource limitations, statutory deadlines) preclude addressing particular
issues or factors contained in mis section, such circumstances wUl be explained
and their impact on the risk assessment discussed.
In addition to the criteria for clarity, transparency, consistency and
reasonableness discussed earlier in this document, OW has adopted the
following policy that applies to the three principles and six key aspects of Risk
Characterization addressed in Section II to help its staff comply with the
Administrator's Risk Characterization Policy. The following points should help
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14
OW's risk assessors characterize risk. These points also provide criteria that can
be used by risk managers to get the most out of risk assessment briefings and to
evaluate the assessor's performance in characterizing risk.
A. S™*nnarv of and Confidence in the Major Risk Conclusions
In preparing risk characterizations for OW, risk assessors should present a
brief statement of .the bottom line of their risk conclusions in simple clear
language. In order to prepare effective risk characterizations, risk assessors
should give a qualitative idea of the major risks and their confidence in the
estimates of risk and conclusions.
The risk manager should be able to read this and know what are the major
risks (or potential risks) to what individuals and populations, and have an idea
of whether the conclusion is supported by a large body of data or if mere are
significant data gaps. Explain in a qualitative narrative any quantitative
estimation of risk to assure that the reader understands the meaning of the
numbers.
B. Summary of Key IsSUCS
Successful risk characterizations in OW require that risk assessors
summarize in clear, concise language the key issues, conclusions, and rationale
from each stage of the assessment paradigm (i.e., hazard identification,
dose-response evaluation, exposure assessment, and/or the integration of these
considerations into a risk assessment).
A key issue is one that is critical in order to properly evaluate the stated
conclusion. The idea is not to repeat the entire hazard, or exposure assessment,
but to summarize and identify those pieces of information that were critical to
the evaluation, so mat the risk manager will be alerted to the major issues and
conclusions that are the bases of the assessment; Short conclusion statements
from the assessments can be repeated, or, if the assessment conclusions are
lengthy, summarized.
In looking at the whole risk picture there may be issues which should be
brought to die risk manager's attention. For example, is there a major imbalance
in the assessments, such that there is a strong case for hazard, but lack of data,
or great uncertainty for exposure; or vice versa.
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15
Guidance to the risk assessors: Criteria for judging how well they
characterize risk in their documents and
1. Briefly discuss the key issues from the reports or data sources used
to make the risk assessment; and
2. Look at the whole risk picture and bring issues to the risk
manager's attention. For example, is there a major imbalance in the
assessment; such mat there is a strong case for hazard, but a lack of
data, or great uncertainty for exposure, or vice versa,
C. Methods Used
Standard Agency methodology is generally followed to generate risk
estimates for each category of assessment conducted by OW. When quantitative
risk evaluations are performed for O W the resultant risk numbers should be
narrated qualitatively to ensure that the reader understands the meaning of the
numbers. When extensive risk assessments are performed, the risk assessor is
likely deviate from using default methodology. Such departures should be
highlighted in the risk characterization.
The mathematics of the risk calculations are not intended to be fully
articulated in the risk characterization. However, the risk manager should be
provided with qualitative, "feel" for the numbers.
Criteria for Judging the, success with which a risk assessor provides this
"feel" in briefings and in written material:
1 . Explain the meaning of standard Agency interpretations of risk
values, (e.g., the hazard quotient) if they are not explained
elsewhere.
2. Explain any specific methodology that might be easily
misinterpreted, (e.g., the use of ecotoxicity population models).
3. If technical data are presented in numerical terms, qualitatively
discuss the data as well. In this regard, the use of tables and
graphics is strongly encouraged, including sufficiently descriptive
titles and narrative.
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16
D. Summary of the Overall Strengths and Uncertainties of the Risk
Assessment
Discuss in qualitative terms, in clear, concise language the overall quality
of the assessment, and the major uncertainties associated with each of its
components. The idea is to relay to the risk manager in frank and open terms
the strengths and weaknesses of .the assessment
An example of possible strengths of an assessment would be that the
overall weight of evidence of the data indicates mat the quality and quantity of
data supporting the hazard and/or exposure is high. There might-also be general
consensus within the scientific community on certain points used to build the
hazard/exposure case. The risk manager needs to know the amount of
uncertainty in each-of the assessment areas, and in the final risk conclusions.
Guidance to risk assessors and criteria for measuring success in conveying
the strengths and uncertainties of the Risk Assessment
1. Review the major uncertainties presented in the characterizations for
each component of the risk assessment paradigm and summarize
them.
2. Discuss the incomplete knowledge and absence of consensus
concerning scientific phenomena which were evaluated in the risk
assessment
3. Apprise the risk manager of the level of understanding, and major
differing viewpoints surrounding the scientific judgments made.
a) Identity what other reasonable alternatives and conclusions
can be derived from the data set.
b) Discuss how other organizations (e.g., industry and
environmental groups) evaluate the risk and the pros and cons
of their evaluations compared to EPA's assessment.
4. Make clear when:
a) precise conclusions cannot be drawn because of uncertainty;
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17
b) conclusions may differ because of variation (e.g., when
children exposed to a chemical are at a different risk from
adults exposed to the same chemical because of their different
susceptibility);
c) the cancer risk is in question because it is not known if the
dose/response model is an appropriate one.
5. Identity major data gaps and, where appropriate, indicate whether
garnering particular data would add significantly to the overall
certainty of the risk.
a) Distinguish between policy-based uncertainty (e.g. 10-fold
uncertainty factors used in noncancer risk estimates or fitting
a Cancer Model to a tumor data set) and biologically-based
uncertainty (e.g., actual mechanism by which noncancer
diseases and cancer are caused).
b) Inform the risk manager mat
1) while providing a number for regulation, research to
reduce policy-based uncertainties is subjective and does
not yield a true measure of uncertainty; and
2) biologically, or other scientifically-based models lead to
definitions of uncertainty in terms that are quantifiable
and directly applicable to humans providing strong,
defensible assessments. However, much tune, money
and effort is needed to develop and validate these
models.
6. Indicate where scientific judgments or default assumptions were
used to bridge information gaps, and explain the bases for these
judgments/assumptions.
E.
Because of the potential for public misunderstanding through
inappropriate, risk comparisons, "comparative" risk discussions (e.g., the risk qf
dying in a car accident compared to the risk of dying in a plane crash) should
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18
not be included as part of the risk characterization effort However, risk
comparisons (e.g., how does the likely risk from this agent compare to others
regulated by EPA) can provide a valuable tool to risk managers. Thus, where
appropriate, compare this risk assessment with past Agency decisions, and ~
decisions by other federal and state agencies, or other countries on the same
chemical. If possible:
1. let the risk manager know how the risks posed by this agent
compares with the risks posed by similar agents EPA has regulated
in the past;
2. describe how the strengths and weaknesses of this assessment
compare with those regulated in the past;
3. let the risk manager know if other risk assessments have been
performed on the agent, so the manager can view this assessment in
its. historical context; and
4. describe the rationale and bases for me other decisions on this agent
if they differ from this assessment
F. Other Information
Indicate any other information which might bear on the evaluation of risk
within the scope of the assessment There may be information that is obvious to
the scientist or technical assessor but not to the risk manager which would assist
in making a risk-based decision. There may be a need to put scientific
arguments used in the assessment into a broader context
OW will evaluate the success of its risk assessors and risk characterizations in
this regard to the extent they:
1. inform the risk manager whether the key data used for the
assessment is considered experimental, state of the art or generally
accepted scientific knowledge;
2. include, where appropriate, information which projects changes in
risk under various candidate risk management alternatives;
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19
3, highlight areas in the assessment which, might be overlooked or
misinterpreted by the risk manager, and
4. make it clear that the risk assessment should be4ised to inform the
risk management decision, not drive it Other factors that most be
considered in addition to risk mat are equally or more important in
arriving at the final decision include:
a. Social (e.g., environmental justice)
b. Economic
c. Policy
d. Legal
G.
Management oversight, internal program reviews and outside, independent
peer review of OW's Risk Characterization Policy is required to ensure
compliance with the policy, to evaluate its success, and to make necessary
improvements. The actions OW will take to establish effective mechanisms for
implementing, evaluating and improving its risk characterization guidelines are:
1. Provide training for risk assessors about what information to present
to risk managers.
2. Provide training to risk managers about what questions they should
ask of risk assessors.
3. Develop a system, with internal reviewers, independent from the
risk assessor preparing the information, to ensure that each risk
assessment and briefing contains a risk characterization consistent
with this policy.
4. Conduct an independent outside review of OW's Risk
Characterization Policy and its application to at least one major
assessment within one year of sign-off of this policy.
5. Conduct periodic reviews of the risk characterization portions of the
assessments thereafter (at least four per year).
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20
X. Statement of Commitment
., Through this Implementation Guidelines document the Office of Water
intends to ensure mat risk characterizations produced by and for this Office-will
be substantially consistent with these guidelines and with Agency guidance and
policy on risk characterization, recognizing limitations in time and resources.
The guidelines will be updated as necessary. Finally, this OW Risk
Characterization Policy Implementation Plan is not proposed to retroactively
change or adjust any risk assessments completed under current OW/EPA
policies. It will apply only to those OW assessments started or revised on
or after 1996.
Assistant Administrator for Water Date
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DRAFT—DO NOT COPY. DISTRIBUTE, OR QUOTE.
APPENDIX E
CASE STUDY HANDOUTS
for
C-l and C-2 Risk Characterization Colloquia
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
APPENDIX E
CASE STUDY HANDOUTS
Case Study A Lavaca Bay
Case Study B . ..Midlothian
Case Study C RCRA Biocrude (OSW)
Case Study D.. Waquoit Bay (OW & Reg. 1)
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DO NOT QUOTE OR CITE
CASE STUDY A
LAVACA BAY
Preliminary Risk Characterization
Regional Risk Characterization Case Study
Risk: Characterization Colloquium
Series C-2
OSWER and EPA Regions
August I & 2, 1996
Dallas, Texas
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.RISK CHARACTERIZATION ISSUES:
LAVACA BAY PRELIMINARY RISK CHARACTERIZATION
GENERAL BACKGROUND . The Super fund Amendments and Reauthorization
Act of 1986 (SARAi as implemented through the National Oil and
Hazardous Substances Pollution Contingency Plan (The NCP) requires
a site-specific baseline risk assessment to characterize the
current and potential threats to human health and the environment
that may be posed by contaminants migrating to ground water or
surface water, releasing to air, leaching through soil, remaining
in the soil and sediment, and bioaccumulating in the food chain.
The results of the baseline risk assessment are used to help
establish acceptable exposure levels for remediating the site. The
ALCOA (Point Comfort) /Lavaca Bay Superfund Site, Point Comfort,
Texas,, was added to the National Priorities List (NPL) or Superfund
list in April of 1994 based on mercury contamination of the ALCOA
facility and in fish, shellfish and sediments from Lavaca Bay.
The Site is comprised of approximately 3,500 acres of an active
facility owned by the Aluminum Company of America (ALCOA), a "400
acre dredge spoil island created by ALCOA and portions of Lavaca
Bay that could encompass an area as large as sixty square miles
making the Site one of the largest in the nation. In 1988*, the
Texas Department of Health issued- a fishing advisory closing an
area of Lavaca Bay to the taking of finfish and shellfish. In 1995
the Agency for Toxic Substances and Disease Registry issued a
report classifying the closure area of Lavaca Bay as an urgent
public health hazard.
ISSUEg. The following issues are presented to encourage
dialogue on the Preliminary Risk Characterization for the Lavaca
Bay Site and on the planning of a comprehensive site-specific
Baseline Risk Assessment and final Risk Characterization: 1) use
of "default" fish consumption rates to estimate human exposure to
met.hylmercury through consumption of fish and shellfish from the
Site, 2) use of the reference dose (RfD) for methylmercury,' 3)
results of the Preliminary Risk Characterization, 4) development
and use of site-specific fish and shellfish consumption rates to
estimate human exposure to methylmercury through consumption of
fish from the Site, 5-) development and use of a site-specific
toxicity value for methylmercury in humans, and 6) the cumulative
risk from multiple contaminants and multiple exposure pathways and
routes from the Site.
GENERAL STRUCTURE AND CONTENT. Preliminary Risk Characterization
was conducted using data assembled in the Preliminary Site
Characterization Report, which summarizes the nature and extent of
environmental conditions at the Site based on existing data. The
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Preliminary Site Characterization Report and Preliminary Risk
Characterization provides a focus for the- Remedial Investigation
(RI) and site-specific Risk Assessment activities that ALCOA is
performing at the Site.
A Community Advisory Group (CAG) has been assembled with
representatives of virtually all interested community segments to
review the RI and risk assessment process in order to communicate
community issues and-make recommendations to ALCOA and EPA. The
Citizens Advisory Group has provided stakeholder input into
reasonable exposure characteristics of the affected population such
as the species and amount of fish and. shellfish consumed by the
local population. Mercury exposure through fish and shellfish
consumption is a major issue to the community because of potential
adverse impacts to human health as well as the local economy.
FINDINGS AND UNCERTAINTIES. A summary of results and limitations
in the Preliminary Risk Characterization are presented as well as
issues related to planning and implementing the comprehensive site-
specific Baseline Risk Assessment. The major issues are presented
below:
Use of "Default" Fish Consumption Rates: The preliminary exposure
assessment used "default" fish consumption rates of 11 g/day, 50
g/day and 150 g/day for general population, recreational fishers
and subsistence fishers/-, respectively. These fish consumption
rates are based upon exposure frequency of .365 days/year. A major
limitation in the use of "default" fish consumption rates is that
important subgroups, such as Asian-American people, may not be
represented by the three categories of fish consumers (general
population, recreational and subsistence). The default consumption
rates could underestimate the mean fish consumption rate of ethnic
groups such as Asian-American people. Several fish consumption
studies indicate that Asian-American people have consumptions rates
greater than the general population. Asian-American people
comprise 2.9% of the ethnic breakdown of Calhoun. County and are
frequent commercial and subsistence fishers in. Lavaca Bay.
Use of the Reference Dose (RfD) for Methylmercury: The current
methylmercury RfD of 1 x 10.'4 mg/kg-day is based upon Iraqi people
exposed to methylmercury-treated seed grain that was mistakenly
used.in home-baked bread.. Major limitations include the precision
of the characterization of the adverse effects in the Iraqi study
and the matrix for the methylmercury exposure. The Iraqi study
called on .mothers to- recall the whether the child walked at 18
months and talked at 24 months in a culture were birthdays are not
important. The raethylmercury exposure in the.Iraqi study was via
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consumption of methylmercury-treated seed grain rather through the
consumption of fish and shellfish.
Results of the Preliminary Risk Characterization: Using data in
the Preliminary Site Characterization Report, the concentration of
total mercury detected in fish caught inside the closure area in
Lavaca Bay was compiled. The mean total mercury concentrations of
1.6 mg/kg, 1.7 mg/kg and 0.9 mg/kg were estimated in black drum,
red drum and blue crab, respectively. ' The "default" fish
consumption rates, the Reference Dose for methylmercury and the
site-specific fish tissue concentration (1.4 mg/kg) were used to
examine the potential for noncarcinogenic health effects. The
Hazard Quotient values (HQs) of 2, 10 and 30 were estimated for the
general population, recreational fishers and subsistence fishers,
respectively. These Hazard Quotient values are greater than unity
(one); therefore these values represent an unacceptable risk from
noncarcinogenic effects from the possible exposure to methylmercury
via the consumption of fish and shellfish taken from the closure
area in Lavaca Bay. These Hazard Quotient values indicate that
potential noncarcinogenic health effects from exposure to
methylmercury could result from the consumption of fish and
shellfish from Lavaca Bay by the general population, recreational
fishers and subsistence fishers. Major limitations include " the
uncertainties surrounding the consumption of .fish and shellfish,
the reference dose for methylmercury and site-specific fish- tissue
concentration of total mercury. These noncarcinogenic risks could
be sufficient to trigger a remedial action as defined by the NCP.
Development of Site-specific Fish Consumption Rates: A site-
specific fish consumption study has been developed to characterize
fish and shellfish consumption rates of aquatic species combined
with catch location for each of the local subpopulations. The
objectives of the study include: 1} determination of species of
fish and shellfish, harvested by local fishers (both recreational
and commercial), 2) characterization o.f human .populations, both
recreational and commercial fishers, who fish in Lavaca Bay, 3)
identification and'characterization of any subpopulations of people
who eat substantially more seafood "from the Lavaca Bay than other
local residents (i.e., subsistence fishers), 4) characterization of
the fate of fish and shellfish commercially taken from Lavaca Bay
(e.g., distributed nationally, within the state or locally), and 5)
description of preparation methods of fish and shellfish taken from
Lavaca Bay (i.e., consumption-of whole fish or fillet). Confidence
in the site-specific fish and shellfish consumption rate is limited
by the study or survey method.
Development of a Site-specific Toxicity Value for Methylmercury:
The current methylmercury RfD is based upon Iraqi people exposed to
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methyImercury-treated seed grain that was mistakenly used in
home-baked bread. Scientific papers were recently published in the
journal, NeurdToxicology, regarding the Seychelles Child
Development Study which examine -the mental and physical development
of children whose mothers consumed fish containing low levels of
methyImercury during pregnancy. The Seychelles study may be a more
appropriate study to derive the methylmercury RfD, particularly
with regard to exposure via fish consumption. Limitations are the
low ambient methylmercury concentrations detected in fish
potentially consumed by people in the Seychelle islands and the
reliance on a single health effects study
Cumulative Risk from Multiple Contaminants and Exposure Routes:
The comprehensive site-specific Baseline Risk Assessment will
examine the risk from-multiple contaminants and multiple exposure
routes from the Site. The comprehensive Baseline Risk Assessment
will evaluate the risk from inorganic and organic chemicals from
the site. Human exposure will be evaluated for multiple exposure
pathways and routes: inhalation of ambient air, ingestion of fish
and shellfish, skin contact with sediments, and direct skin contact
with sediment and water. .Limitations are the ability quantify the
adverse effects and exposures from.mixtures of chemicals and from
multiple exposure pathways and routes.
CONTE'XT AND COMPARISON ISSUES. The Preliminary Risk
Characterization would lead the Risk Assessor and Risk Manager to
conclude there is potentially an unacceptable noncarcinogenic risk
from exposure to methylmercury from the consumption of fish" and
shellfish from Lavaca Bay. The Preliminary Risk Characterization
could be used by the Risk Manager to propose a remedial action such
as further restrictions on fishing in portions of Lavaca Bay or
dredging contaminated sediments in Lavaca Bay. The Risk Assessor
and Risk Manager must decide if uncertainties can be reduced by
developing site-specific exposure and toxicity estimates versus
using "default" exposure and toxicity values. If uncertainties- in
the- Risk Characterization are reduced, the Risk Manager could make
a more limited remedial action (e.g., dredge less sediment) and
could be more confident the human health and the environment are
protected.
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TOPIC: Preliminary Risk Characterization
ALCOA (Point Comfort)/Lavaca Bay Superfund Site,
Point Comfort, Texas
BACKGROUND INFORMATION:
• The Site is comprised of an active 3,500 acre facility
owned by the Aluminum Company of America (ALCOA), a dredge
spoil island created by ALCOA and a portion of Lavaca Bay.
The Site was added to the Superfund list in 1994 based on
mercury contamination of the ALCOA facility and the bay.
• EPA and ALCOA entered into an Administrative Order on
Consent (AOC) under which ALCOA is performing a Remedial
Investigation and Feasibility Study (RI/FS) and risk assess-
ment. EPA, the State and the natural resource trustees have
entered into a Cooperative Management Agreement to facili-
tate involvement -in the RI/FS process.
• A Community Advisory Group has' been assembled with repre-
sentatives of virtually all interested community segments to
review the RI/FS and risk assessment in order to communicate
community issues and make recommendations to ALCOA and EPA;
CURRENT STATUS:
• ALCOA prepared a Preliminary Site Characterization Report,
which summarizes the nature and extent of environmental
conditions at the Site based on existing data.
• ALCOA is conducting a Fish and Shellfish Consumption
Survey and Fish Tissue Sampling.
COMMUNITY' CONCERNS:
• In 1988 the Texas Department of Health issued a fishing
advisory closing an area of Lavaca Bay to the taking of
finfish and shellfish. In 1995 ATSDR-has classified the
closure area as an urgent public health hazard.
• Mercury exposure through fish consumption is a major issue
to the community both for the potential adverse impacts to
public health as well to the local economy.
TECHNICAL CONCERNS:
• Use of "Default" Fish Consumption Rates: The exposure
assessment used "default" consumption rates of one fish meal
every three weeks, three fish meals every two weeks and five
fish meals every week for general population, recreational
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fishers arid subsistence fishers, respectively. A major
limitation in the use of "default" fish consumption rates is
that people, such as shrimpers who consume by-catch, may not
be represented by the three categories of fish consumers.
• Use of the Reference Dose (RfD) for Methylmercury: The
current rcethylmercury RfD of 1 x 10"5 mg/kg-day is based
upon Iraqi people exposed to methylmercury-treated seed
grain that was mistakenly used in home-baked bread. Major
limitations include the precision of the characterization of
the adverse effects in the Iraqi study and the matrix for
the methylmercury exposure. " The Iraqi study called on
mothers to recall the whether the child walked at 18 months
and-talked at 24 months in a culture were birthdays are not.
important. The methylmercury exposure in the Iraqi study
was via consumption of methylmercury-treated seed grain
rather through the consumption of fish and shellfish.
• Results of the Preliminary Risk Characterization: Using
existing data, the concentration of total mercury detected
in fish caught inside the closure area in_ Lavaca Bay was
compiled. The mean total mercury concentrations of 1.'6, 1.7
and 0.9 mg/kg were estimated in black drum, red drum and"
blue crab, respectively. The "default" fish consumption
rates, the RfD for methylmercury and the site-specific fish
tissue concentration (1.4 mg/kg)- were used to examine the
potential for noncarcinogenic health effects. The Hazard
Quotient values (HQs) of 2, 10 and 30 were estimated for the
general population, recreational fishers and subsistence
fishers, respectively. These HQs are greater than one;
therefore these values represent an unacceptable risk from
noncarcinogenic effects from the possible exposure to meth-
ylmercury via the consumption of fish and shellfish taken
from the closure' area in Lavaca Bay. These HQs indicate
that potential noncarcinogenic health effects from -exposure
to methylmercury could result from the consumption of fish
and shellfish from Lavaca Bay. Major limitations include
the uncertainties surrounding the consumption of fish and
shellfish, the RfD for methylmercury and site-specific fish
tissue concentration of mercury. These noncarcinogenic
risks could be sufficient to trigger a remedial action as
defined by Superfund.
• Development of Site-specific Fish Consumption Rates: A'
site-specific fish consumption study was conducted to char-
acterize fish and shellfish consumption rates combined with
catch location for general population and recreational-
fishers * Additional survey is- being developed to evaluate
consumption of shrimp by-catch. Confidence in the site-
specific fish and shellfish consumption rate is limited by
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the study or survey method.
• Development of a Site-specific Toxicity Value for Methyl-
mercury: The current methylmercury RfD is based upon Iraqi
people exposed to methylmercury-treated seed grain that was
mistakenly used in home-baked bread. Scientific papers were
recently published in the journal, NeuroToxicology. regard-
ing the Seychelles Child Development Study which examine the
mental and physical development of children whose mothers
consumed fish containing low. levels of methylmercury during
pregnancy. The Seychelles study may be a more appropriate
study to derive the methylmercury RfD, particularly with
regard to exposure via fish consumption. Limitations are
the low ambient methylmercury concentrations detected in
fish potentially consumed by people in the Seychelle islands
and the reliance on a single health effects study
• Cumulative Risk from Multiple Contaminants and Exposure
Routes: The comprehensive site-specific Baseline Risk
Assessment -will examine the risk from multiple contaminants
and exposure routes from the Site. Human exposure will be
evaluated for multiple exposure pathways and routes: inha-
lation of ambient air, ingestion of fish and shellfish, skin
contact with sediments, and direct skin contact with sedi-
ment and water. Limitations are the ability quantify the
adverse effects and exposures from mixtures of chemicals and
from multiple exposure pathways and routes.
FUTURE/PROPOSED ACTIONS:
• The Risk Characterization leads to the conclusion that
there is a potentially unacceptable risk from exposure to
methylmercury from the consumption of fish and shellfish
from Lavaca Bay. This characterization could be used to
propose, remedial actions such as dredging contaminated
sediments. Should uncertainties be further reduced by
developing site-specific exposure and toxicity estimates
versus using "default" exposure and toxicity values? If
uncertainties in the Risk Characterization are reduced,
remedial actions could be restricted (e.g., dredging-less
sediment) while being confident that human health and the
environment are being protected.
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r— en
> o J.I
;o
Environmental
Rl Workplan for the
Alcoa (Point Comfort) / Lavaca Bay Superfund Site
Volume B7a: Fish and Shellfish Consumption Study
Phase I - General Population Survey
October 11,1995
ALCOA
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October 11, 1995
1.0 INTRODUCTION
In February 1994, the Alcoa (Point Comfort)/Lavaca Bay Superfund Site (the Site) was listed
on the National Priorities List (NPL). The primary reason for listing the Site was the fact that
mercury has been found in some fish species taken from Lavaca Bay, and that some of the
fish and blue crabs sampled exhibited mercury concentrations in excess of the FDA action
level of 1 ppm. Subsequent to that listing, Alcoa entered into an Administrative Order of
Consent {AOC) with Region VI United States Environmental Protection Agency (USEPA).
According to the AOC Statement of Work, Alcoa must perform a baseline risk, assessment for
human health as part of the Remedial Investigation/Feasibility Study (RI/FS) for the Site. A
site-specific study of the consumption of fish and shellfish caught from Lavaca Bay will be
required to quantitate risk in human health for the baseline risk assessment. This workplan,
the first in a series of two, presents the methods to be used in determining the prevalence of
recreational and commercial fishing in general as well as the seasonality of fish locations in
the Bay (if any). The second workplan will be based upon the findings outlined in this
workplan, and will detail the methods for determining species-specific consumption rates for
fish and shellfish taken from Lavaca Bay by local populations.
1.1 BACKGROUND
An EPA (1992) literature review determined that fish consumption rates differ throughout the
country and for specific subpopulatioris. The use of an "average" consumption rate for typical
households, recreational fishers, and subsistence fishers, based on national or even regional
data, may not accurately reflect the local consumption rate for a particular subpopulation.
The use of inappropriate assumptions may overestimate or underestimate the risk associated
with the consumption of contaminated fish tissue by the community in general or specifically
by members of these subpopulations.
Subpopulations that may be taking fish and/or shellfish from Lavaca Bay include recreational
and subsistence fishers and individuals involved in commercial fishing operations.
Recreational fishers may catch fish from contaminated sites for sport, but may or may not
consume them, while subsistence fishers may be obtaining a large proportion of their diet
RAOtAttWOMCPlAHSl
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October 11, 1995
from contaminated sources because they cannot afford to purchase other foods. There are
also commercial fishing operations, which obtain fish on a larger scale to provide these items
to communities. National surveys of fish consumption fail to target these subpopulations,
including recreational and subsistence fishers and their families, and thus may over- or
underestimate risk. An EPA (1992) review concluded that detailed surveys are warranted to
target subsistence and recreational fishers to obtain a more accurate fish consumption rate
for these groups.
The Preliminary Site Characterization Report (PSCR) (Alcoa, 1995) identified consumption of
fish and shellfish from Lavaca Bay as a potentially significant pathway, based on the detected
concentrations of mercury .in fish and the relative importance of Lavaca and Matagorda Bays
as recreational and commercial fisheries. The PSCR identified target populations such as
recreational fishers for whom site-specific consumption rates should be derived consistent
with the EPA (1992) recommendations.
1.2 PURPOSE
The overall objective of the fish and shellfish consumption study is to characterize fish and
shellfish consumption rates of aquatic species combined with catch location for each of the
local subpopulations. This primary objective will be achieved by addressing tile following
objectives:
• Determination of the species of fish and shellfish harvested by local fishers
(both recreational and commercial);
• Characterization of the populations, both recreational and commercial, who fish
in Lavaca Bay (city of residence, how often they frequent the survey area to
fish, how often they consume seafood taken from the survey area);
• Identification and characterization of any subpopulations who eat substantially
more seafood from the survey area than other local populations (i.e.,
subsistence fishers);
RAMAN: WORWIAN.S1
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October 11. 1995
• Characterization of the fate of fish and shellfish commercially taken from the
survey area (e.g., distributed nationally, within the state, or locally); and
• Description of preparation methods of fish and shellfish taken from the Bay
(i.e., consumption of whole fish or fillet}.
The overall target population of the fish and shellfish consumption study is the residents of
the six-county area surrounding Matagorda Bay. However, because consumption rates based
on national surveys may not accurately reflect local consumption rates for subpopulations
within this overall target population, as explained in Section 1.1 above, the consumption study
has been divided into two phases. The first phase, which is the phase described in this
workplan, has two objectives. The first objective is to determine whether default exposure
frequency assumptions adequately represent ingestion of fish and/or shellfish for two
important subgroups in the target population. The first of these is recreational fishers in the
six-county area. The second subgroup is the "general population," which includes all area
residents except commercial fishers, which will be addressed separately in Phase II. The
general population subgroup includes the recreational fishers subgroup, as well as subsistence
fishers and non-fishers. The second objective of the Phase I study is to determine whether
subsistence fishers make up a significant portion of the target population.
The information gathered in Phase I will be used to define the data needs for Phase II. If the
Phase I data indicate that exposure frequencies for either recreational fishers or tine general
population are significantly different from default ingestion rate values, or that subsistence
fishers comprise a significant proportion of the target population, then the Phase II study will
be structured to collect the quantitative data necessary to derive site-specific exposure
frequency estimates. Otherwise, the Phase II study will focus only on gathering qualitative
data, such as information about the species of fish consumed by the target population,
sources of fish, and so forth.
This workplan uses EPA guidance including:
• Assessing Human Health Risks from Chemically Contaminated Fish and
Shellfish: A Guidance Manual IEPA-503/8-89-002. September, 1989a);
RADIAN: WORKPLAN. 51
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Revision M
October 11, 1995
• Guidance for Assessing Chemical Data for Use in Fish Advisories Volume llt
Risk Assessment and Rsh Consumption Limits (EPA 823-B-94-004, June
1994a»;
• Consumption Surveys for Fish and Shellfish. A Review and Analysis of Survey
Methods (EPA 822/R-92-OO1, February 1992); and
• Guidance for the Data Quality Objective Process (EPA QA/G-4, September
1994b).
RAOUN:WOAXFIAN.SI
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Revision F-1
October 11, 1995
2.0 SITE SETTING
Regional and site setting are discussed in detail in Sections 3.1 and 3.2 of the PSCR. A
summary of relevant information from the PSCR is presented here. The Site (Ftgure 2.0-1)
is located on land adjacent to, and on the east side of, Lavaca Bay and south of State
Highway 35. The eastern boundary of the Alcoa property is adjacent to Cox Creek and Cox
Cove. The Alcoa facility is bounded on the south by Cox Bay. The Site comprises
approximately 3,500 acres and includes both the plant and Dredge Island. The Dredge Island
was built upon a naturally occurring formation by disposal of clay and dredged soils from area
ship channels (Figure 2.0-1).
Lavaca Bay and associated smaller bays {Cox Bay, Chocolate Bay, and Keller Bay) are part of
the Matagorda Bay system. Lavaca Bay and Cox Bay have surface areas of approximately 64
and 8 square miles, respectively and ranges in depth from less than 1 to 9 ft. Cox Cove
includes an extensive marsh area located in the northwestern portion of Cox Bay. A
navigational channel runs from the Gulf of Mexico to Matagorda Bay, to Lavaca Bay and into
the Lavaca River, with a side channel to the Alcoa and Calhoun County Navigation District
Docks. Matagorda Bay and its secondary embayments are broad and relatively shallow, and
have large areas exposed to persistent southeasterly winds. As a resurt, wind-induced mixing
maintains vertically homogeneous conditions throughout the estuary except within the
Matagorda Ship Channel. Mud (a classification from McGowen and Morton, 1979 - see PSCR
Section 3.1.7.3} is the dominant sediment type in the Matagorda Bay system. Mud is
predominantly clay with mixtures of silt, sand, and shell. Most of the mud that covers the
floor of the Matagorda Bay complex was transported to the area by the fresh water rivers
such as the Lavaca River. Sand is chiefly found in the bay margins and tidal inlets. Oyster
reef is dominant in many parts of Lavaca Bay.
Fishing facilities are numerous in the general survey area and include public boat ramps,
docks, and bait shops. Fishing, both in the area bays and in the Gulf of Mexico, is a viable
portion of the local economy. Ftgure 2.0-2 identifies the main fishing facilities in the area
(Calhoun County Guide to Good Fishing, Port Lavaca/Calhoun County Chamber of Commerce
and Agriculture).
RAMAN:WOMCPUN.S1
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w
f : , ;>4
«<;,;•->> ••w./.'--/ • uf: •:,•'••
:. • .'
• ».i - rr; • >.
«•„»«' . '•'• ;.- •••
ij&i$IpJSv$-
sy'f^N AUtttO *•- ' • l<**t-*;*^Sk*"' »•''" '• •!'''s '.f; ' ''.i
8£ACM — * - »;> ^Hfc -.:--.^'j v,rr
8
Figure 2.0-1, Site Location
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Revsion R-1
October n. 1995
Lighthouse Beach Fishing Pier
Plar* **daR**iB. PuMc BMGIX Boat Ramp. R.V.
Harbor of Refuge
Pubic Boat Ramp. Accra n Chocofali Bay* LMOI
Good WMar R**IO. rtllgan * Trout
Magnolia Beach
PuMc teat R«np. ACCMI m MiaarirM. Bay.
Public DMCTI Pmik.
Indianola Fishing Center
Boot Ramp, R*wrg
Boggy Bayou
Wao* FMng. Cjn»»m» tor Trout 4 Roundar
A Port O'Connor Beach Park
9 Clark's Fish House Restaurant & Marina
ooutt Rawnp. TacMc. fl^st, ^^vm^^t DoflC Sip*, cHoaAavY OinnQ
Q Port O'Connor Fishing Center
_ Tmplil. Ba«. Fu«
A Ctoc's Oodc
PuMc Baal Ramp& FW*io SupplM. BaK Fual. Tour
SCALE: KILOMETERS
0 4
SCALE: MILES
0 2.5
A Po/nf Comfort Boat Ramp
Pubic Boal Ramp. L*»aa Bay Aeon* lo Pl»f 4
Trout A R«Jtan
O/ma Boat Ramp
Pubte Boat Ramp. Aoora « Kator Bar
•»« • AT I O •
Figure 2.0-2. Area Rshing Facilities
RAO LAN: WORKPOKS1
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Revision F-1
October 11, 1995
2.1 SITE HISTORY
The Texas Department of Health fTDH) Division of Shellfish Sanitation has sampJed fish,
crabs, and oysters from this area since the 1970s. In the earty 1970s, mercury levels in
oysters and crabs were found to be significantly elevated when compared to the FDA
guideline of 0.5 ppm. Based on these findings TDH closed parts of Lavaca Bay to the
harvesting of oysters. This ban was lifted in October 1971 when the levels of mercury
dropped below the 0.5 ppm action level. The TDH continued the sampling and analysis of
seafood and issued public health warnings in 1978 and 1981. On April 20, 1988, the
Commissioner of HeaJth issued a measure prohibiting the taking of finfish and crabs from a
specific part of Lavaca Bay (Texas Department of Health Aquatic Life Order 1, 1988) which
is now known as the Closed Area (Figure 2.1-1). The most recent closure document is
provided in Appendix A. Oystering and shrimping are not prohibited. The current FDA action
level of mercury in fish tissue is 1.0 ppm (TDH, 1994). The PSCR summarized the data
available from previous sampling and analysis of fish collected from inside and outside the
Closed Area.
2.2 AREA DEMOGRAPHICS
Brief demographic information is presented here for surrounding counties with emphasis
placed upon Calhoun county. The demographic area of interest is located in the Texas
Coastal Send and includes the counties of Calhoun, Jackson, Victoria, Matagorda, Aransas
and Refugio (Figure 2.2-1). Population centers in these areas include Rockport-Fulton,
Refugio, Seadrift, Port Lavaca, Palacios, and Matagorda. victoria (population 55,076) is the
largest city in the area, and is located 30 miles inland from the Gulf of Mexico; all of the other
cities mentioned are on or near the coast. Major roadways running parallel to the coast
include U.S. Highway 59 and State Highway 35. Many state highways run perpendicular to
the coast, intersecting highways 59 and 35.
This portion of the Texas Coastal Bend serves as a year-round coastal retreat for many urban
areas of south Texas. San Antonio, Austin, Houston, and Corpus Christi are all within an
approximate 150-mile radius of the area and weekend fishers are expected to be numerous.
RAOtAN:WOMCPlAN.S1 p -tg
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Revtsjoo F-1
Oeaoto«M1. 1995
ALCOA
. .: ' • ' ' "• .
• • . • ¥•
. ; ...:. :,
• -; • •
'•':-,.-. .. '
• m-
ft
COXPT.
COX BAY
CLOSED PORTION
OF THE BAY
SCALE : KILOMETERS
Q_ ..1.25
SCAtH: MILES
0 075
JVQ0127 0624/96
Rgure 2.1-1. Closed Portion of the Bay
RADIAN WO«KP1>N 51
E-20
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MATAQORDA
AL AGIOS
T COMFORT
PORT
LAVACA
ROCKB0RT
/
ARANSAS
NOTE:
COUNTY BOUNORIES SHOWN,
ISLANDS AND WATER FEATURES
OMITTED.
JVO0063 03/1*96
Figure 2.2-1. Area Counties
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Revision F-1
October 11, 1995
Recreational activities include fishing, bird watching, beach combing, swimming, boating,
skiing, wind surfing, hunting, camping and goifing. Matagorda Island State Park, Aransas
National Wildlife Refuge and Lake Texana State Park are all located in this region.
Campgrounds, hotels and condo rentals are available throughout the area.
Calhoun County
In 1990, the population of Calhoun County was 19,053. The number of people employed in
Calhoun County increased from 9,428 in 1990 to 11,141 in 1993. Some of the major
employers in Calhoun County include Formosa Plastics Corporation, Union Carbide, BP
Chemicals, and Alcoa. The per capita personal income averages $15,417 and the median
family income in Calhoun County is $28,418, an increase of 68.9% from 1980 (Port
Lavaca/Calhoun County Chamber of Commerce and Agriculture, 1994). The employment
composition of Calhoun County is shown in Table 2.2-1.
The ethnic breakdown of Calhoun County is as follows: 56.0% white, 36.3% Hispanic, 2.9%
African American, 2.9% Asian and 2.0% other. Slightly more than 75% of the population
of Calhoun County lives within one of the four major cities (Port Lavaca, Seadrift, Port
O'Connor, and Point Comfort). Smaller communities include Alamo-lndianofa-Magnofia Beach
and Olivia-Port Alto. Port Lavaca is the center of commerce for Calhoun County, the county
seat and major population center (10,886 -1990 census). The city has an active commercial
fishing and shrimping industry and continues to promote the area as a recreational fishing and
tourism destination as well. Seadrift.is located in southern Calhoun County, and has a
population of around 1,300 residents. Most residents are commercial fishers and construction
workers (Alcoa, 1995). Point Comfort is a small residential community with a population of
956 - a decrease from 1,027 in 1980 (Port Lavaca/Calhoun County Chamber of Commerce,
1994). Port O'Connor is located at the end of Texas Highway 185 in southern Calhoun
County and offers sport fishing and hunting. Boats depart from Port O'Connor to the
Matagorda Island State Park and Wildlife Management Area. Matagorda Island is a barrier
island that contains federally owned lands managed by the Texas Parks and Wildlife
Department.
RADIAN: WOmCFUN.51
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Revision F-1
October 11, 1995
TABLE 2.2-1
EMPLOYMENT COMPOSITION OF CALHOUN COUNTY
EMPLOYMENT CATEGOSY
Manufacturing
Construction
Trade
Service
Government
Finance, Insurance and Real Estate
Transportation
Agriculture
Mining
EMPLOYED PEOPLE
<%OFTQTAU
33
19
17
13
11
3
2
1
T
Source: Port Lavaca/Calhoun County Chamber of Commerce
and Agriculture, 1994
RAOMN:WOnCPUN.St
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Revision F-1
October 11, 1995
Community attitudes and concerns about the Alcoa project were initially assessed in the
development of the Community Relations Plan which was prepared in accordance with the
requirements of the AOC. Key community concerns, issues and attitudes were gauged on the
basis of telephone and in-person surveys. The surveys took place in August and September
of 1994. In both the telephone and in-person interviews, community members identified
mercury contamination of Lavaca Bay as their main environmental concern; some of those
interviewed reported concerns about possible economic consequences - primarily the
disruption of commercial fishing in the Bay - of any potential cleanup at the Site. Other
environmental concerns included contamination of fish and seafood, effects of pollution on
fishing, contamination worsening as a result of cleanup actions, and contamination spreading
and affecting the food chain (Alcoa, 1995).
2.3 SIGNIFICANT AQUATIC SPECIES
Biota within the region around the Site is dynamic with regard to aquatic and terrestrial
ecosystems, however terrestrial ecosystems are not pertinent to this study. Ecological
communities comprised predominately of marine marsh grasses such as Spartina are common
in Lavaca Bay and provide habitat for aquatic biota such as phytoplankton, .zooplankton,
benthic invertebrates, waterbirds, turtles and fish. Additional information on aquatic species,
with particular emphasis on shellfish and finfish important for human consumption, is
summarized below. These summaries are based on limited data, and are intended to provide
an overview rather than a detailed review.
2.3.1 Shellfish
Commercially important shellfish that occur in the Lavaca Bay area incfude American oyster
(Crassostrea virginica), blue crab (Ca/linectes sapidus), white shrimp (Panaeus setiferus) and
brown shrimp (Penaeus azteca). There are several oyster reefs/beds with scattered
occurrences throughout Lavaca Bay and fewer occurrences in southern Cox Bay (Figure
2.3-1). Oysters, feed by filtering phytoplankton and zooplankton from the water column.
Prohibition of oyster harvesting is usually a result of bacterial accumulation, particularly fecal
coliforms. Oysters are consumed by crabs and black drum (Alcoa, 1995). Except for shrimp,
RADUN:WORKPUkN.S1
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Revision F-1
October 11.1995
LAVACA
BAY
SOURCE: ALCOA. 1994
RADIAN: WORKPLAN.S 1
Figure 2.3-1. Location of Oyster Reefs and Shell Areas
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Revision F-1
October 11, 1995
American oysters led the commercial catch from Lavaca Bay from 1975 to 1991 in value
while blue crab dominated the catch in weight and was second in value (TPWD, 1990).
The blue crab is the most common of the crabs and is found throughout Lavaca and Cox
Bays. Blue crabs are opportunistic feeders, eating whatever is available, including both plant
and animal material, although their preference is for animal matter such as small fish, young
oysters, and shrimp. Blue crabs, especially the small ones, are, in turn, consumed by some
of theSarger fish such as spotted seatrout, black drum and red drum.
White shrimp is the most common of the two commercial shrimp species (white and brown)
found- in Lavaca and Cox Bays. Both shrimp species consume plankton and organic matter,
which are generally found in the shallower, marshy areas of the estuaries. Life expectancy
is approximately one year. They are important food items for the red drum, spotted seatrout,
sand seatrout and southern flounder (Alcoa, 1995).
2.3.2 Finfish
Of the numerous species of fishes found in Lavaca and Cox Bays, several are common
throughout the two bays and are important sport and/or commercial species. The larger of
these fish include black drum (Pogonias cromis), red drum (Sciaenops ocellatus), southern
flounder (ParaJichthyslethostigma) and spotted seatrout (Cynoscion nebulosusl (AJcoa, 1995).
Spotted seatrout was the most frequently sport-caught species in Lavaca Bay. Sand seatrout
(Cynoscion arenrius), red drum, and black drum were the second, third, and fourth most
frequently sport caught species, respectively, from 1974 to 1987 (TPWD, 1988).
Spotted seatrout inhabit bays during the spring and summer, moving into deeper waters in the
fall and winter, then returning to the bays in the spring. The larvae inhabit the grassy areas
until they reach two years of age, at which time they start migrating in and out of the bays.
Females grow at a faster rate compared to males, generally averaging two to three inches
longer than a male of the same age group. Food items vary with age, with smaller fish eating
small crustaceans, shrimp and fish, while adults consume primarily other fish. Studies
conducted by Alcoa in 1992 indicated that these fish were as prevalent in the Closed Area
RADIAN:WORKPIAN.S1
E-26
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Revision F-l
October 11, 1995
in the spring (April/May) as the fait (November), with the exception that most of those caught
in the fall were in deeper water, with, few caught north or northeast of the Dredge Island
(Figure 2.0-1). Moseley and Copeiand {1973} indicate that spotted seatrout were more
common in the winter and spring compared to the summer and fail, although they were
classified as common in only five of the 16 sampling events in Cox Bay. The minimum size
possession limit is 15 inches, with no upper length limit (Alcoa, 1995).
Sand seatrout do not grow as large as the spotted seatrout, attaining not much more than
20 inches in length. Sand seatrout feed on fish and crustaceans. They are common in deep
bays, channels, and the Gulf (TPWD, 1993).
Red drum are most commonly found in shallow water, particularly in areas with vegetation
and mud, as well as around oyster reefs. Red drum spend their first three years in the bays
and estuaries, then move into the offshore waters, where they remain for the rest of their
lives. Young red drum consume small crustaceans such as copepods, amphipods and shrimp.
As they grow and mature, their diet changes to mostly larger crustaceans such as shrimp and
crabs, and small fish such as mullet and menhaden. Red drum are abundant in Lavaca Bay,
but rarely occur in Cox Bay. They most likely would be abundant in Cox Cove, due to the
large area of grasses and soft substratum, but there are no data to substantiate this. They
can be caught and retained between 20 and 28 inches in length (Alcoa, 1995).
The habitat of the black drum can vary widely from shallow « 1 m) to deep (> 100 m)
waters, from low to high salinity, from clear to murky waters and from warm to cold water
temperatures. Tagging studies of fish less than four years old by Osburn and Mattock (1984)
indicated that 85% of the marked black drum were recaptured in the same bay within a short
distance of release, with 11 % being recaptured in an adjacent bay and 4% recaptured in open
waters. Their diet varies with age. Young black drum are opportunistic feeders of small
organisms, particularly small shrimp, crabs, fish, crustaceans and polycheates. Older fish eat
primarily molfusks and crabs, but also polycheates and small fish. Although there are
extensive grass beds in Cox Cove, there are few oyster areas, so the occurrences of black
drum may be limited by the food sources available. The size limit for possession by fishers
is 14 to 30 inches, which roughly corresponds with ages one to 14 years (Alcoa, 1995).
RAOMfeWOnCFlAN.S1 _ __
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Revision M
October 11, 1995
Southern flounder are found in the bays during the spring, summer and faH, at which time
they generally leave to spawn in the Guif. Larval fish enter the bays, where they inhabit
grassy areas. They reach maturity at approximately two years of age, when the females are
between 12 and 16 inches long. Females tend to be larger than males. Young fish consume
mostly crustaceans, but as they grow older, other fish become prevalent in their diet, along
with larger shrimp. These fish are common in Lavaca Bay, but rare or uncommon in Cox Bay.
There are no data indicating occurrence in Cox Cove. The minimum legal catch limit size is
12 inches with no maximum length (Alcoa, 1995).
*ADIAN:WORXPIAN.S1
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Revision F-1
October 11, 1995
3.0 CONSUMPTION STUDY METHODOLOGY
The purpose of the fish and shellfish consumption study is to provide information needed to
quantify ingestion of fish and- shellfish from Lavaca Bay by both local and distant
subpopulations. Section 6.1.3.2 of the PSCR provides a complete discussion of potentially
exposed populations for the Site. As discussed below in Section 3.1, area demographics and
activities strongly suggest the presence of subsistence fishing populations. In addition,
because of the prevalence of recreational fishing in the Texas Coastal Bend area, the standard
exposure assumptions used for fish consumption by recreational fishers may not adequately
represent the fishers in this area. The consumption study has been designed to collect
information about all populations that consume fish from Lavaca Bay. Each of these
populations will be targeted separately.
Insufficient data are available at this time to develop a statistically-based data collection plan.
For example, although the numbers and locations of recreational fishers in the area can be
inferred from fishing license statistics, the extent to which they fish in Lavaca Bay is
unknown. The proportion of the population that eats fish given as gifts by recreational fishers
is also unknown. Estimates of the population in the area that eat fish caught recreationally,
bought in local stores or a commercial fishing docks, and/or served in local restaurants are
necessary to design the population-specific surveys, as well as to determine the combined
consumption of fish from all sources. In addition, information on where (or if) specific finfish
species may be found in the Bay is needed to design appropriate fish sampling plans and to
determine the optimum timing for the surveys of recreational fishers. Therefore the study will
be conducted in two phases/ with information from Phase I used to complete the design of
Phase II.
Figure 3.0-1 shows the components of the fish and shellfish consumption study. From
Phase I the following information will be gathered:
RAOIAN:WOnCPlAN.S 1
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Revision F-1
October 11.1995
FISH/SHELLRSH CONSUMPTION STUDY
I
r
• Overall goaf:
Quantification of consumption of
fish/shellfish from Lavaca Bay
PHASE I
I
FISHING GUIDE INTERVIEWS
TPWD FISH DATABASE
GENERAL POPULATION STUDY
. |
PHASE II
I
1
aal fishers
unities
>
f
Sport
fishers
^
r
Subsistence
fishers
1
Markc
char
• Commercial
fishers
• Wholesaler
• Distributor
• Restaurant
Figure 3.0-1. Components of Rsh and Shellfish Study
RADlANrWORXPUUtSt
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Revision F-1
October 11,1995
• Comparison of recreational fishing frequency to standard default assumptions;
• Identification of subpopulations (if any) with fishing frequency consistent with
subsistence fishing; and
• Location and times of the year when each finfish species is present in Lavaca
Bay.
The general population survey will tie together the recreational, commercial, market, and
restaurant surveys to allow an estimate of combined ingestion of fish from all sources. It will
also provide data for a statistical comparison of fishing frequency in this area to standard
(default) assumptions. This first phase will include gathering information on the life habits of
the fish present in the Bay (i.e., where and when they can be found). Using this information,
Phase II will be designed. Figure 3.0-1 shows the components of Phase I!. The spatial and
temporal information (which finfish species is located where and when) will be used in the
development of the sport-fisher and subsistence fisher surveys and the fish sampling plans.
Emphasis will be placed on questions about fish .consumption in the second phase of the
study. Demographic information will also be collected. The following subsections present
information on the target populations, describe the Data Quality Objectives, and present the
methods to be used in Phase I.
3.1 TARGET POPULATIONS
The potential target populations and their possible sources of fish are shown in Table 3.1-1,
and are depicted in Rgure 3.1-1. Consumption patterns for noncommercial fishers are
assumed to vary widely. Some may consume fish for one week during a year or for several
weekends each year (short-term). Others may consume fish for much longer periods during
a year or may rely on fish year-round as a major part of their diet. Within these groups are
some individuals that may be more susceptible to contaminants, including women of
reproductive age, children and persons with pre-existing hearth problems. Sport fishers have
been shown to have higher fish consumption rates than the general U.S. population; the
potential for large exposures over short time periods make them especially susceptible to
health risks as compared to non-fishers (EPA, 1994a).
RAMAN: WORKP1AN.51
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Revision F-1
October 11, 1995
TABLE 3.1-1
SOURCES OF FISH FOR TARGET POPULATIONS
TARGET POPULATION
SOURCES* OF FISH
RECREATIONAL FISHERS
Sport fishers
Subsistence fishers
Consume personal catch, eat in local
restaurants, and buy fish and shellfish from
local commercial fishers or vendors
COMMERCIAL FISHERS
Commercial fishers
Subsistence fishers
Commercial fishers and their families could
consume by-catch, fishers could also eat in
local restaurants
LOCAL POPULATION
In general, sub-groups are expected to be identified
by fishing frequency (sport, subsistence, seasonal)
but ethnic classifications may also be used.
i •• — - > • •
Local population could eat in local restaurants,
buy fish srC shellfish from local commercial
fish markets or vendors
RADMUfcWOnCPlAN.SI
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RavwcnF-1
October 11,1995
POSSIBLE EXPOSURE PA THWA YS
Direct To Consumer
Through Fish Markets
Or Roadside Vendors
Direct To Restaurant
Consumption Of By-catch
By Commercial Fishers
And Fishers' Family
Consumer
Distributor/Processor
Commercial
Catch SoW
COMMERCIAL
FISHERS
SUN*?, Mot*
Consumption By Fisher"
And Fisher's Family
RECREATIONAL
RSHERS
Restaurant
Restaurant
Employees
GENERAL POPULATION
Receive Fish. From
Friends And Family
Consumer
Figure 3.1-1. Possible Exposure Pathways
RADIMtWORKPlAKSI
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Revision F-1
October 11, 1995
Because 19% of the county population is below the poverty level, subsistence fishing may
be occurring. Subsistence fishers eat self-caught fish as a major source of protein in their
diets, for a greater percentage of the year than do recreational fishers. Subsistence fishers
may catch fish using the same techniques as recreational fishers (e.g., rod and reel at a fishing
pier) or may include for example commercial shrimpers that take home fish and shellfish that
are trapped in the nets with shrimp (i.e., the by^catch). Subsistence fishers may prepare fish
differently than other groups; they may use the whole fish in soups, or consume more highly
contaminated tissues, such as the fiver, brains and subcutaneous fat. Both their longer
exposure durations and consumption habits may increase the exposure of subsistence fishers
to contaminants taken up by fish compared to those who do not fish or fish for shorter
periods of time. Some populations may subsist on non-commercial fish year-round, including
recent immigrants accustomed to self-sufficiency and fishing, particularly Asian-Americans
(EPA, 1994a).
In addition to recreational and subsistence fishers in the area, the population in the area may
ingest fish from the area by buying fresh fish/shellfish obtained from Lavaca Bay at local
grocery stores or at commercial fishing docks. They may also be served meals at local
restaurants that include fish and/or shellfish taken from the Bay. Finally, people living in the
area may eat fish and/or shellfish caught from Lavaca Bay that were given to them by friends.
The target population who may ingest fish that have taken up contaminants from the Bay
include these members of the general population as well as those who fish for themselves
and/or their families.
3.2 DATA QUALITY OBJECTIVES FOR THE GENERAL POPULATION SURVEY
Data Quality Objectives (DQOs) are a description of the "quality of data needed to enable the
project team to make decisions." Structured according to the EPA guidance provided in
Guidance for Planning for Data Collection in Support of Environmental Decision Making Using
the Data Quality Objectives Process (EPA, 1993 QA/G-4) this description typically includes
the following:
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How do you obtain
This is a survey of Coastal Bend residents to investigate the ways you
get fresh seafood. These survey results will be used as part of a larger
study offish and shellfish consumption patterns in the communities
near Lavaca Bay. The goal of the study is to gather information from
people who fish-or eat fish-from Lavaca Bay in order to understand
all aspects of commercial and recreational fishing in this area.
Please return your completed survey in the enclosed envelope by
Questions or comments?
Call Laurel Cahill, Alcoa Point Comfort Operations, 512/987-6500, or
if you are calling long distance, 1-800-82&8596.
We appreciate your help!
£-35
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Fish and Shellilst Sarvey
Please answer each of the following questions about you and anyone residing in your household.
If you are unsure of the exact answer, please give your best estimate.
Please place n V in die most appropriate box.
1) How often do you eat fish you bought from fish markets, docks or grocery stores near your home?
D more than 3 times a week D 1-3 times a week Q twice a month Q once a month Q 34 times a year D rarely or never
2) How often do you purchase oysters/crabs from fish markets, docks or grocery stores near your home?
Q more than 3 times a week D 1-3 times a week D twice a month Q once a month C 3-4 tunes a year Q rarely or never
3) Do you purchase more fish during certain times of die year? D yes D no
3a) If yes, during which seasons?
ummer Gune, July, Aug., Sept) D Fall (Oct, Nov., Dec.) D Waiter (Jan., Feb.) D Spring (Mar., Apr., May)
4) Do you purchase more oysters/crabs during certain times of the year? D yes D no
4a) If yes, during which seasons?
Q Summer (June, July, Aug., Sept.) D Fall (Oct., Nov., Dec) D Winter (Jan., Feb.) D Spring (Mar, Apr., May)
5) How often do you eat fish in local restaurants?
D more than 3 times a week D 1-3 times a week Q twice a month Q once a month D 34 times a year D rarely or never
6J How often do you eat oysters/crabs in local restaurants?
D more than 3 times a week Q 1-3 times a week Q twice a month D once a month O 34 times a year D rarely or never
7) Do you fish recreationally in Lavaca Bay? O Yes D No
8) Dp you fish commercially in Lavaca Bay? O Yes Q No
9) How often do you eat fish you caught from Lavaca Bay?
G more than 7 times a week D 5-7 times a week O 34 times a week D 23 times a~week O 4-6 times a month D 3 or less times a month
10) How often do you eat oysters/crab* you took from Lavaca Bay?
Q more than 7 times a week Q 5-7 times a week D 34 times a week D 2-3 times a week D 4-6 times a month D 3 or less times a month
11) How often do you eat fish caught by Mends or family members and given to you?
D more than 3 times a week D 1-3 times a week D twice a month O once a month O 34 times a year D rarely or never
12) How often do you eat oysters/crabs caught by friends or family members and given to you?
O more than 3 times a week D 1-3 times a week D twice a month D once a month O 34 times a year D rarer/ or never
i
How many people live in your household?
Are there children under the age of 6 years living in your home? D yes Q no
E-36
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Figure 6.IS-I
SITE-WIDE PRELIMINARY CONCEPtUA
SITE MODEL. OFF SITE RECEPTOR
•^ __________ — _—____— ___——_——_
RElCASC MECHANISM EHVlRQNMfNUL tfiANSPORI AND fAlt
VololUimlnn k. a, D.lpi/.tel | »[
iiS|4'p«rtltiltlA"iiii3»5«nir~ P* • " "••
L» ' • *** b' ° ' ~~~
(W*l Md dry) I. _ _ _ ^_ _^~«P~_. — — _ — — __ — «~ — .- — «.._.„__._.»»
^_ .*» Agricultural uM soufc** — — *p> «— *-fttef upfoiio 6y crops (H usid for hrlgoUon)- *~
ground woUr mlgrallan .
J-<" to up a • y pun uis or r go on)—*-
0 -f -j- o ptoko y pi 9 J
!_,_?_____,______ _ _
udmwnli J I
1
1 I Rool uptaho by ptonlt (if wtod lot watering) —
|— ^ Aa/l*u*li«al wM f eu*<* - ^ <— ^ — ^ B4«t w«4«li* by «'»**(" uud for Irrlgalton)- »-
; .„ ^0
%-. __ sutturfoc« lrrlg«tien *- — Agrkutlwel UH tourct - — — f* "" r **•* uplafe* by crops (II ui«d tor Irrigation)* «»
' ••dinwnlt (U«ac« toy)
~-* ApM.nl yM »*-reo y-r-S^I u^oko by cropi (If uiod fw Imgotton)- *»
^s
HUMAN tXPOSUqE
lAg*«lian al moal and dairy pfoducd
Inhololion el ompltnl air
tnytflion of m*of ond doifp p«nju(l»
tng«ilion ol soil
Skin conlecl -iih toil
Ingtslion ol (foil* and vtg*Mbl*s
Ingttlion of ntfol and dairy products
Shin conlKl -Ih drJnbln8 -ol.r
tngostien et iruMs «nd ««g*taM*i
Ingtslbn of fruft* and *«gt! clos« lo toureo
Skin tenlacl
Ingtilion of drinking »al«r
Skin canlocl wllh drinking wiltr
lng»>1io«i ol lruU» and vtgtl'ibtft
fnhetolion of vapors (t.g.,du>(ng sno»ir)
'tngcsllon of (Ith
Ingtllwn of fruils and vigtlablos
Ingoslian ol m«al and dolry p«oducii
Skin canlacl «ilh/(nc(d4nt«l ln««»ti«n el *aU<
InhDlobon of »opo'* Ctcit IB s0u/<»
Skin conlocl »llh/ Ineidtnlol lng«»H0n
Ingiillon of Iruili end wgtlabUt
Ing •! lion ol moo) ond dairy predutls
Ingtslion ol drinking «olo(» (« g .duitng thovtf)
IngsilLon of lish or shoiifith I
Ingtslton of Irulls and ««g«tiip4«i
lng«sli«n ol mial ond dairy product*
Skin conlocl -ilh/lflcfcfailel Ir^illofl of *»\*t
Inhalation el vepars clot* lo tourco
Slitn contact with «*dlm*ntt |
Skin conlecl «rllh/lncld«nlal Inaosllwi qt toil
Inftoitlan af fish or •hiNllth 1
— *y
Legend
—X" PolhwO)r is Inconipldl*
— — — Polhwoy is Complolo.
Probably nul Siyuilicaiil
Significant
Notes
(•« futtt mttm •« «t« •• •»•* ••«»« *4^>*
® Ay*u<^***a •••• 1* IM* «f*« •«» •*«•«•
V ^
f >
^ BLOCK 15
StTEWIDe
^ ^i.i. — 'A/il ^
-------
HEALTH
WARNING!
iADVERTENCIA
PARA LA SALUD!
THONG TIN BAG DONG
VE SUC KHOE
CLOSED
AREA
(AREA CERRADA)
DO NOT Eat Fish or Crabs Caught in Closure Area of The Bay (See Map)
No comer peces ni cangrejos pescados en el area cerrada de la bahia (vease el mapa)
KHONG nen an ca hoac cua bat trong khu vile cam vinh nay (ban do dinh kern)
The arM shown on tht map It cloaed lo the taking
of flan or craba dut to mtrcury contamination
Eating flah or craba from tha doaura araa la
prohUMlad and may ba hazardous to human health,
especially for chtldran and fatuata (unborn cMldrtn)
Keeping flah or craba from tha clotura araa may ba
punishable by a fina o) up to $500
Pescando paaaa o cangreioa de la a*r«a cerrada
)e»taprohlbk
damarcurlo.
rvMcwnnr |>w»v» w v» w
(viaee el mapa) aata prohiMdo deMdo a la
contamination da ma
Comer paacadoa o cangra)oa da la ares carrada
puada aar pellgroto, aapeclalmente para nlfloa
y fatoa (nmoa aon por nacer).
El guardar pecee o cangraioa del area cerrada
puide reauttar an una mulla da haata $500.
Taxaa Department of Health,
Seafood Safety DMalon
(512)719-0215
February 1996
Khu vtJc an d|nh trong ban do I* phf m
vl cam'khdng dityc bit c* hofc cua bdl
ly do b| 6 nhlem chit d^c ihtiy tlnh.
An ci hof c cua bat trong khu vuc cim
la phfm phap va c6 Ui< nguy hl«m din
tdc khoa, nhal Ik aiJc khoa cua u4 em
va bao thai (hal nhi chtla ainh ra).
Bal ho$c glu1 ca hof c cua Irong khu
elm co th« D) phf t khoing $500.
-------
DO NOT QUOTE OR CITE
CASE STUDY B
MIDLOTHIAN CUMULATIVE RISK
ASSESSMENT
Regional Risk Characterization Case Study
Risk Characterization Colloquium
Series C-2
OSWER and EPA Regions
August I & 2, 1996
Dallas, Texas
E-39
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E-40
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RI8X CHAaACTDZ3ATZOV
KZDX.07BZAH CUXULATZVB ftZSX
General Background.
On November 13, 1994, the Environmental Protection Agency
(EPA) announced its Hazardous Waste Minimization and Combustion
Strategy and Hazardous Waste Minimization National Plan. The
plan presents EPA's goals to expand public involvement in
hazardous waste combustion issues, to pursue hazardous waste
combustion enforcement and compliance efforts/ and to develop and
impose controls on combustion facilities to ensure they do not
pose an unacceptable risJc to human health and the environment.
To assess risJc to human health and the environment all
boiler and industrial furnace (BIF) and incinerator permit
application reviews include a risk assessment. To implement this
requirement, a multi-source, multi-pathway screening risk
assessment was conducted to estimate the cancer risk and
potential non-cancer risk health effects from three cement
companies and one steel mill in Midlothian, .TX. Because the
facilities are located between 0.7 and 5 miles of each other, it
was theorized that the combined emissions from the facilities
could result in cumulative health effect*.
ues.
The following topics are presented to focus issues and
encourage dialog on risk characterization issues that were
identified in the Midlothian Cumulative Risk Assessment: 1)
cumulative risk; 2) modeled concentrations versus measured
concentrations; 3) data gaps and use of surrogate data; 4) dioxon
breast milk risk; and S) PM 10 emissions. The Midlothian
Cumulative Risk Assessment is a Category ZI assessment as defined
by OAR's draft Risk Characterization Implementation Statement.
This risk assessment was conducted to support the state of
Texas's consideration of an application by one cement kiln to
burn hazardous waste as fuel. The stats of Texas is the
authorized regulatory body for issuance of hazardous waste
combustion permits* The risk characterization must be
understandable to stats permit writers and to personnel from the
industrial facilities whose emissions were evaluated in the risk
assessment. The draft permit, which is based- in part upon risk
assessment results, is required to be public noticed. Therefore,
the risk characterisation must also be understandable to area
residents, politicians, and environmental groups.
The risk characterization is broken into three major
components, results,, limitations, and conclusions. The results
E-41
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section further ctioned irto background information in which
acceptab risk ran. 9 are .set rsrth, results by receptor
location id an ove.all summary of results. The limitations
section p s«nts the limitations and uncertainties associated
with; emi ;ion rates, use of EPA standard default values, ISC3
air modeling, and exposure scenarios. The conclusions section
presents risk assessment conclusions and the rational used to
come to these conclusions. The section also presents a
comparison of measured and modeled soil concentrations and uses
it to assess the conservativeness of the fate and transport
models.
Findings end Uncertainties.
A summary of study results and the strengths and limitations
of risk assessment methodology used are included in the risX
characterization. Major issues addressed are .described below.
Cumulative Risk: . Cumulative risk was addressed in the risk
characterization as the combined effects of maximum exposure to
emissions from the four Midlothian facilities. Maximum exposure
concentrations were determined by overlapping of deposition and
air concentration plumes from the four facilities in the study.
Maximum deposition rates occurred at three separate locations for
groups of chemicals of concern differentiated based on chemical
fats and transport characteristics. The three chemical groupings
were dioxon-like compounds, other organics, and metals. Risk was
determined for site-specific sensitive receptors (i.e. adult
resident, child resident, subsistence farmer, subsistence fisher)
nearsst to each of the three locations of maximum deposition.
Modeled Coaoeatratioas versos Measured Coaeeatratioas: In the
screening risk assessment, threshold levels were exceeded for
lead and antimony and were at the threshold level for cadmium and
mercury. Potential exposure from these four metals were driven
by emissions from the steel mill. Ttis steel mill has been in
operation for twenty years and modeled values project
concentrations based on thirty years of operation. The risk
characterization compares modeled concentrations, measured
concentrations, local background, and U.S. background.
Data Qaps aad Use of surrogate Data: It is described in the risk
characterization how data gaps are filled with conservative
assumptions. An exampls of this would be the usa of standard EPA
default assumptions for parameters such as inhalation and
consumption rates, body weight and exposure duration and
frequency. Emission rates were not available for the steel mill
and surrogate data was used. The risk characterization describes
the uncertainties associated with the use of surrogate data.
After release of the report, the steel mill submitted data which
indicated the emission estimate for. antimony was overly
conservative-. However, the new data did not change the overall
conclusion of the report.
E-42
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Dioxon Br«»st Milk Risk: The risk characterization presented th«
results of calculations of the amount of dioxon ingested by the
breast feeding infant per. day due to exposure to emissions and
compared this to the amount of dioxon ingested by the breast
feeding infant per day due to average adult background exposure
to dioxon. The appropriateness of this comparison and the
uncertainty associated with it were not discussed in. the risk
characterization.
PX 10 Emissions: This was an area of concern brought out by the
public after release of the report which was not addressed in the
risk characterization. Based on data collected by the state of
Texas, regulatory personnel knew that PM 10 emissions were within
regulatory levels of concern.
?7Ptf3rt ilrt 771g*git?B Issues; Comparisons in the risk
characterization were made between the sources of risk and non-
cancer exposure attributed to each of the four study facilities
and to the combined risk. Comparisons were also drawn between
risks from cement companies versus risk from the steel mill.
Measured soil and water concentrations were used to assess the
surrogate date and the fate and transport model results
identified in the study.
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E-44
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RISK CHARACTERIZATION COLLOQUIUM
OVERVIEW OF MIDLOTHIAN CUMULATIVE RISK ASSESSMENT
Multimedia Planning and Permitting Division
U.S. Environmental Protection Agency
Region 6
1445 Ross Avenue
Dallas, TX 75202
June 1996
E-45
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E-46
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1. INTRODUCTION
This document presents an excerpt overview of screening
level risk estimates for direct and indirect exposures
attributable to emissions from three cement companies and a steel
mill located in Midlothian, Texas. Region 6 developed the
estimates by following the procedures outlined in the U.S.
Environmental Protection Agency's (EPA) draft Guidance for
Performing screening Level Risk Analyses at Combustion Facilities
Burning Hazardous Wastes. The risk estimates presented in this
document are limited by the uncertainties inherent in the models
and the data upon which the analysis is based.
Region 6 attempted to minimize uncertainties by
evaluating and incorporating area data collected by the
Texas Natural Resource Conservation Commission,
requesting emission rate information directly from each
of the facilities,
developing emission rates based on tests conducted at
similar facilities when no specific data were provided,
and
analyzing the data provided for the facilities against
data from other sources to evaluate its overall
reasonableness.
Releases associated with combustion sources were modeled
using facility-specific emissions rates, stack characteristics,
and estimated representative receptor locations around the
facility. The four human exposure scenarios that were considered
include an adult and child resident, a subsistence farmer, and a
subsistence fisher.
This document is divided into 4 sections. Section 2
provides a sits characterization and description of exposure
scenarios and pathways. Section 3 provides an overview of the
risk assessment results. Section 4 presents the risk
characterization which is partitioned into sections describing
the limitations of the analysis and its conclusions. Attachments
and references in th« text are not provided hers.
2. STUDY ABB* MID BOOSTOB PARAMBTBft OVBBVXBW
2.1 characteristics of Study Area
The ares subject to this study is located approximately 30
miles south of the Dallas-Pt. Worth metropolitan area. Proa
Texas Industries (TXZ; see Map 1), the study area extends 8 miles
north to Joe Pool Lake, 3 ailes south, 3 miles east, and 6 miles
west. The area is characterized by small hills and valleys with
elevations generally ranging from approximately 800 feet mean sea
E-47
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level south of TXI to 500 feet mean sea level at Joe Pool Lake.
Predominant wind direction'is from the south.
Chaparral Steel Corporation (CSC) and TXI are the two
southern most facilities. CSC is located 0.7 miles southwest of
TXI. North Texas Cement Company (NTCC) and Holnam Cement Company
are located approximately 4 and 5 miles northeast of TXI,
respectively.
With the exception of the city of Midlothian (approximate
population of 5100) which is located approximately 3 miles
northeast of TXI, the land use of the study area is predominately
agricultural with some industrial development. The area is home
to several small cattle operations and rural residential
developments. Gardens were sighted at many homes in the area
during several site visits.
In addition to Joe Pool Lake (surface area approximately
7600 acres), the area also contains two privately owned lakes
known as soil Conservation Service (SCS) Lakes 9 and 10 (combined
surface area of approximately 84 acres). SCS Lakes 9 & 10 are
located approximately 2 to 3 miles northwest and north,
respectively, of the CSC/TXI complex very near residential
developments.
2.2 Scenarios and Pathways
The four human scenario* that were considered in this
screening level risk assessment are the. subsistence farmer, the
adult and child resident, and the subsistence fisher. The
individuals included in each of these scenarios were assumed to
be exposed to contaminates from the emission sources via
ingestion of above-ground vegetables, incidental ingestion of
soil, consumption of drinking water and direct inhalation of
particles and vapor*. These exposure scenario* differed
primarily in their consumption of certain food*. Specifically,
only the subsistence farmer was assumed to consume contaminated
beef and milk, whil« only the subsistence fisher wa* assumed to
consume contaminated fish. Because the drinking water supplied
to the area surrounding the facilities comes fro* Joe Pool Lake,
exposure via contaminated drinking water was considered under all
of the scenario*.
Although differences in consumption are the primary
difference between the scenario*, other differences exist. The
ingestion rat* of soil and above-ground vegetable* and the
inhalation rat* of air differ for the child and the adult
scenario*. $xposur* duration i* another difference. The adult
resident and fisher are assumed .to be exposed for 30 years, the
subsistence farmer for 40 years, and the child exposed for 6
years. Attachment 3- lists all the exposure parameters used in
E-48
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calculating risks to the four human scenarios.
The watersheds and water bodies considered in the analysis
were selected from U.S. Geologic Survey (USGS) topographical maps
and on information collected during a visit to Midlothian. The
selected water bodies and watersheds that were included in the
analysis are those that would be large enough to support fish and
reflect the highest impact from the facilities. In addition, one
of the water bodies selected (i.e., Joe Pool Lake) was identified
as the City of Midlothian's primary drinking water source based
on information from the Texas Department of Health. As a result,
Joe Pool Lake was modeled as the drinking water source. The
topographic maps were used in identifying the watersheds
associated with each water body and in estimating water body and
watershed surface areas.
The SCS Lake 9 & 10 watershed includes Cottonvood Creek and
portions of the Newton Branch of Soap Creek. The SCS Lake
watershed is also a subsection of the Joe Pool Lake watershed.
Assuming that the SCS Lake watershed is sufficient to support
subsistence fishing is conservative because the true viability of
the SCS Lake watershed to support subsistence fishing is
unknown.1 Nevertheless, Region 6 assumed that these water bodies
could potentially support subsistence activity based on their
size and heir nearby proximity to residential development.
Furthermore i these water bodies are in an area that could be
significantly impacted by the facilities' emissions due to their
near central location to the facilities being evaluated in the
study.
Contaminants were assumed to be emitted from the four
facilities at the emission rates/ not identified in this
overview, 24 hours/day, 7 days/week, 365 days/year. EPA's air
dispersion model ZSCSDFT was employed to estimate the transport
of the contaminants to the surrounding area. Soil was assumed
to become contaminated by wet and dry deposition of particles and
vapors» Above-ground vegetation/ for human and.animal
consumption, were assumed to become contaminated via deposition
of particles on plants, transfer of vapor phase contaminates, and
uptake through the roots. Beef and milk were assumed to be
contaminated via ingestion of contaminated forage (including
hay), silage, grain, and soil*. Fish and .the drinking water
source were assumed to be contaminated by deposition directly
onto the water body and through contaminants transported to the
water body via storm water. Additional modeling data are
presented in Attachment C. Example calculations are presented in
Attachment O*
1 Be* or 9» SCS He* «• prMsy owns! Th« prcpely ipon wHdi 9CS10 9m norths* mo*. Me) ii
toottd • ported • No
E-49
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Map 1 identifies the points of maximum air concentration and
combined deposition based on estimated constituent-specific
emission rates. As seen from this map, there were three points
of maximum air concentration and three points of maximum
deposition identified. For each compound, these points were
typically located in close proximity to the facility emitting the
compound at the highest rate. Map l also shows the general
location of each site specific receptor evaluated in the study.
In the original draft of the report, risks at the maximum
locations were estimated and reported. However, based on
comments from several reviewers, Region 6 did not report risk at
the maximum receptor locations in this final version of the
report. Reporting risk at the maximum receptor locations was
judged to be overly conservative because such an analysis would
have required Region 6 to assume that maximum deposition and air
concentrations occur at the same location. Such a phenomenon is
not indicative of the model and would result in overly
conservative estimates of risk in some instances.
Rather than estimate theoretical worst case risk. Region 6
obtained information regarding the location of several potential
resident and farm locations likely to be most impacted by the
facilities.2 Thi* information'was obtained during several sit*
visits that were conducted during the summer of 1995. Three
site-specific residents, subsistence fishers and subsistence
farmers were identified and modeled in the analysis. Multiple
receptor* wear* considered in order to ensure that the maximum
media concentration* of each pollutant wer* considered because
the overall risk* for each pathway could vary ^according to which
contaminant was deposited at the highest rat* or wa* present at
the highest ambient air location. Resident Al and subsistence
farmer Al, resident Bl and subsistence farmer B2, and resident Cl
and subsistence farmer C3 ar* th* receptor* located closest to
the points of maximum combined deposition A, B, and c,
respectively. Th*i expoced individual* assumed to live at
residence Al, Bl, and Cl included the adult and child resident
and th* sub*i*t*nc* fi*h*r. Th* difference between th* adult.
r**id*nt and sub*i*t*hc* fi*h*r was that th* fisher wa*
additionally *xpo**d through th* consumption of contaminated
fish.
• ft void be noted fat fa*i tooMki* do not nKHHrty ratatit duri ratidrat wd to IT* bMd on
ntrtfvr
^•*M*1J ^M^^A ' B^^» ^_^^^^^^^ m^^^^^^^^^^
•UHJf VI* ra> **nfi*\ rHDV**
sndvei F*ii*wwe*lfci*t*Jb**dontti>pT**noBpf Kvtfodcar ben type srudbm intt
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Map 1:
Points of Maximum Combined Deposition and
Air Concentration
E-51
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3. SUMMARY OF RESULTS
The national risk, or probability, that an individual may
develop some form of cancer from everyday sources, over a 70-year
life span, is estimated at three in ten. Activities such as too
much exposure to sun, occupational exposures, or dietary or
smoking habits contribute to this high risk. The three in ten
probability is considered the "natural incidence" of cancer in
the United states.
In the Superfund program, EPA established an excess
acceptable lifetime cancer risk range from one in ten thousand to
one in one million. This range may be expressed as 1 x 10*' to
1 x 10"* (expressed throughout this report as 1E-4 to 1E-6) . For
example, a risk of 1 x 10*6 means that l person out of one
million could develop cancer as a result of a lifetime exposure
to a emissions from the four facilities studied in this
assessment. In the Superfund program, EPA must consider the need
to conduct remedial action at a site if the risk exceeds l x 10*6
and EPA usually requires remedial action at locations vhere
excess cancer risks are greater than 1 x 10*4 (1 excess cancer
case in ten thousand people could potentially occur).
The level of concern for non-carcinogenic contaminants is
determined by calculating a Hazard Quotient (HQ) or Hazard Index
(HI). An HZ is the SUB of the HQS for several chemicals that
affect the same target organ. If the HQ or HZ equals or exceeds
on*, there may be concern for potential exposure to sits
contaminants. EPA typically considers the need for taking a
remedial action at locations vhere the HQ or HZ values equal or
are slightly greater than 1.0 for human populations who may
reasonably be expected to be exposed. EPA usually requires
remedial action at locations where RQ or HZ values significantly
exceed one..
This risk assessment estimates theoretical cancer risk and
the potential for theoretical non-cancer health effects from 30
years (beginning today) of emissions, associated with CSC, NTCC,
TXZ, and Holnam. Me cancer risk above regulatory levels of
concern were identified. Theoretical and conservative modeling
estimates that there is the potential for non-cancer health
effects. However, as explained in more detail in the Section 5,
actual sits data shows that the models used, over predict media
concentrations of the principle contaminants driving the
potential for theoretical non-cancer health effects; antimony and
cadmium.
The most significant theoretical cancer risk is attributed
to the ingestion of fish caught from SCS Lakes 9410. Arsenic
contributes up to 80% of the risk from this pathway. Other
pathways that result in the significant theoretical risk are
subsistence farming, and subsistence fishing in Joe Pool Lake. A
E-52
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combination of organic contaminants such as dioxin, BAP and DEHP
drive the subsistence farming risk while arsenic again dominates
the subsistence fishing risk.
The theoretical modeling shows a potential for non-cancer
effects from exposure to antimony in drinking water, and cadmium
and mercury through the ingestion of fish from SCS Lakes 9 & 10.
The HQ for antimony is estimated to be three for adults and six
for children at every receptor location. The HQ for cadmium
equals one for the subsistence fisherman that fishes SCS Lakes 9
& 10 and the mercury HQ equals one for the subsistence fisherman
that fishes both SCS Lakes 9&10 and Joe Pool Lake.
The chronic oral reference dose for antimony (0.0004
mg/kg/day) contains an uncertainty of factor of 1,000. An
uncertainty factor of 1000 means that the critical amount of
antimony found in laboratory studies to cause potential non-
cancer health effects vas multiplied by 1000 to account for
uncertainties in the studies before that value vas used in this
study to estimate the potential for non-cancer health effects.
Critical health effects from studies upon which the reference
dose is based include a decrease in median life span, a decrease
in nonfasting blood glucose levels, altered cholesterol levels,
and a decrease in the mean heart weight of males. Table l
presents the overall results of the risk assessment process.
The chronic reference dose for cadmium (0.001 mg/kg/day for
food and 0.0005 mg/kg/day for water) contains an uncertainty
factor of 10* Critical health effects attributed to cadmium
include anemia and pulmonary disease, edema,' pneumonitis,
possible.effects on the endocrine system, defects in sensory
function, and bone damage.
Citizens in the local area also requested that Region 6
consider risk to infants from dioxin via the breast milk pathway
and risk from a tire fir* that occurred in December, 1995,. at a
tire shredding facility located in the study area. To address
the risk via the breastmilk pathway, Region 6 used the Screening
Guidance methodology to estimate an infant's daily intake of
dioxin if the mother ware a. resident, subsistence farmer, or
subsistence fisher. These estimated intakes were than compared
to an infants background exposure to dioxin through ingestion of
breast milk. Based on the modeled values, an infant's estimated
daily intake of dioxin is 0.01 pg/kg/day if the mother is a
resident, 0.45 pg/kg/day if the mother is a subsistence farmer,
and 0.38 pg/kg/day if the mother is a subsistence fisher. All of
these intakes are less than 1% of the comparison value of 46
pg/kg/day which is the average daily dose an infant would obtain
from background levels of dioxon in breast milk.
E-53
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Re:, n 6 cor rered inc:. ng tr * effects of the December
tire fire n this .essnent, vas nable to complete the
evaluatic Because .f a iicfc 01 ..ata concerning the actual
emission races of contaminants luring the tire fire and the
uncertainties associated with using a methodology based on long-
term chronic exposures to estimate the effects from a short-term
event.
Finally, Region 6 conducted a qualitative analysis of the
combined effects of windblown cement kiln dust (CKD) emissions
and the contaminant emissions specified in this study. This
qualitative analysis was conducted by comparing "best estimates"
of high end baseline risks outlined in EPA's Report to Congress
on Cement Kiln. Dust with the maximum theoretical risk estimates
presented in this report. A quantitative analysis cannot be
performed because the exposure assumptions and fate .and transport
methodologies used in the two studies contain some differences.
However, the comparison does provide a general feel for the
overall contribution of CKD emissions to the theoretical risk.
estimated for the area.
As discussed above, the most significant cancer risk
identified in the study was to a subsistence fisherman at a level
of 1E-4. Pathways contributing to this risk include ingestion of
fish, ingestion of drinking water, incidental ingestion of soil,
ingestion of vegetables, and inhalation. The CKD Report to
Congress provides a "best estimate." of high end baseline risk
from the ingestion of fish contaminated by CKD at 4E-6. Risk
from ingestion of surface water contaminated by CKD .emissions are
estimated at 1E-8. Risk from the ingestion of soil contaminated
by CKD are estimated at 1E-7. Risk from ingestion of vegetables
is estimated at 2E-6 and risk from inhalation is estimated at 2E-
12. All of these risks added together do not materially affect
the most significant estimate contained in this report of 1E-4.
Thus, the uncertainty associated with the failure to
quantitatively assess risk from the emissions of CKD does not
appear to be significant.
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Table 1 Overall Direct and Indirect Cancer Risk
Across All Carcinogenic Chemicals
Scenario
Adult Resident
Child Resident
Subsistence Fisher
Subsistence Paner
Adult Resident
Child Resident
Subsistence Pisaenan
subsistence Pax»er
Adult Resident
Child Resident
Subsistence Plsbezswn
. Sttbeistence pane*
Theoretical
Risks
Points JU.
7E-6
3E-6
SCS
Lakes
9 & 10
9S-S
Joe
Pool
Lake
3B-S
5B-S
Point* 112
3B-5
1I-S
SCS
Lake*
9 £ 10
12-4
. Joe
Pool
Lake
51-5
41-5
Poiae* Cl
41-5
21-5
SCS
LaJces
9 * 10
1K-4
Joe
Fool
Lake
6B-5
61-5
4. RZ8X
4.1 Limitation*
This section discusses the limitations and uncertainty
associated with this screening level cumulative) risk assessment.
The. degree to which the uncertainty needs to be quantified and
the amount of uncertainty that is acceptable varies with the
intent of the analysis. For a screening level analysis such as
this, a high degree of uncertainty is often acceptable, provided
E-55
-------
that conservative assumptions are used to bias^potential error
toward protecting human health.
Uncertainty can be introduced into a health risk assessment
at every step in the process. Error occurs because risk
assessment is a complex process, requiring the integration of
The release of pollutants into the environment,'
The fate and transport of pollutants in a variety of
different and variable environments by processes that
are often poorly understood or too complex to quantify
accurately;
The potential for adverse health effects in humans as
extrapolated from animal bioassays; and
The probability of adverse effects in a human
population that is highly variable genetically, in age,
in activity level, and in life style.
Even using the most accurate data with the most
sophisticated models, uncertainty is inherent in the process.
4.2 Uncertainty
Uncertainty of data used to estimate risk or potential
health effects for emission rate data, exposure parameters, air
modeling, and exposure scenarios are described below.
4.2.1 Emission Rates
The availability and quality of chemical-specific emission
rates presented on* of the largest sources of uncertainty.
associated with this screening level assessment. For the cement
manufacturing.companies, the majority of the emission rates were
based on trial burn data. Because there was only limited data
and information on the quality of the data obtained during the
trial burns (e.g., percent recovered) and the representativeness
of the operating conditions during the trial burns, the
representativeness of these emission rates could not be fully
evaluated. To address this source of uncertainty, the emission
rates used in the analysis were compared across available data
sources (i.e. trial burn data, TNRCC data. Company reported data)
to ensure that the selected emission rates were reasonable while
still being conservative enough to allow for operational upsets
and the uncertainty associated with the quality of the data.
Region 6 is confidant that the ratas.prasantad ara as'reasonable
as can be provided given the availability of accurate data. In
fact, one of the outside reviewers noted that emission rates for
dioxin were consistent with EPA's experience in preparing the
E-56
-------
Estimating Exposure to Dioxin-Like Compounds (draft) report.
Another significant source of uncertainty in the overall the
process is the use of emission rates for CSC that were based on
the assumption that baghpuse and fugitive emissions contained
concentrations of contaminants similar to those found in steel
mill baghouse dust. Although contaminant concentrations emitted
to the atmosphere from the baghouses are unlikely to contain
concentrations greater than those found in the dust, the fugitive
emissions could contain higher concentrations than those found in
the baghouse dust since are emissions that have not yet been
treated. In addition, the volume fugitive emissions could be
more or less than assumed in this study because CSC's actual
fugitive emissions have not been measured. Hence, the
uncertainty in the emission estimates for CSC are significant.
One area of uncertainty that has been addressed since the
review of the draft report by outside experts is the uncertainty
associated with assumed baghouse dust emissions profile. The
emissions profile sets forth concentrations of contaminants that
are very similar to CSC actual baghouse dust data with the
exception of antimony and hexavalent chromium.
The lack of any method to check the viability of antimony
and hexavalent chromium emissions is significant because.both of
these contaminants contribute to the overall cancer risks and
non-cancer effects estimates. Antimony emissions were based
solely on the baghouse dust profile contained in the Detailed
Summary of Information Collection Request Responses For Electric
Arc Furnaces (ZCR). The ICR is based upon data from both
stainless and non-stainless steel mill facilities. CSC
reportedly operates a non-stainless steel mill. Hexavalent
chromium emissions were estimated by assuming that the hexavalent
chromium emissions constituted only two percent of total chromium
emissions. This assumption of two percent is based on a table
included in the Agency for Toxic Substances and Disease
Registry's Toxicologrical Profile for Chromium. The actual
amounts of antimony and hexavalent chromium emitted by CSC are
unknown.
4.1.2 Exposure Parameter Uncertainty
Another area of uncertainty includes the use of standard EPA
default values in the analysis. These include inhalation and
consumption rates, body weight, and exposure duration and
frequency, which are- standard default value* used in most EPA
risk assessments. These parameters often assume that the exposed
population is homogenous, when in fact variations exist among the
population. Using a single point estimate for these'variables
instead of exposure parameter probability distributions ignores a
variability that may influence the results by up to a factor of
E-57
-------
two or three.
Other parameters that are subject to uncertainty are used to
estimate the chemical concentration in the media and locations of
interests. The meteorological data from the Dallas/Fort Worth
National Weather Station provided an approximation of the
meteorological conditions at tha site as no site-specific data of
sufficient quality were available. Different meteorologic
conditions can influence the risk results by up to an order of
magnitude given the same facility characteristics and surrounding
land uses.
Another area of uncertainty is the use of EPA verified
cancer slope factors, Reference Doses and Reference
Concentration. These health benchmarks are used as single point
estimates throughout the analysis. These benchmarks have both
uncertainty and variability associated with them. However, the
EPA has developed a process for setting verified health benchmark
values to be used in all EPA risk assessments, with the
exception of the dioxin and BaP toxicity equivalency methodology
all health benchmarks used in this analysis are verified through
the EPA's work groups and available on the EPA's Integrated Risk
Information System.
4.1.3 Limitations of ISCJTDFT Air Modeling
The indirect exposure model used in this analysis is EPA's
current methodology for addressing a variety of exposure pathways
important for chemicals that bioaccumulate and persist in the
environment. Implementation of this methodology requires air
dispersion modeling results for wet and dry depositions and air
concentrations of particles and vapors in a variety of settings.
ISCSTDFT is the only air dispersion and deposition model
currently available to provide such.estimates from combustion
sources located .in both complex and non-complex terrains.
ISCSTDFT was released as a draft and has not been widely applied
in the present form*
4.1.4 Uncertainty Associated vita Scenario*
The exposure scenarios included in this screening level
assessment-include an adult and child resident, a subsistence
fisher and a subsistence farmer. Although a distribution of the
characteristics (e.g., consumption rates) of each type of
receptor are reasonably veil characterized, population
distributions for the modeled behaviors and activities have not
been adequately studied. For example, little is known about the
fraction of the general population that consists of subsistence
farmers and fishers. Without population distributions for these
receptors, the number of people likely to be exposed to
contaminated media cannot be determined and, therefore, the
E-58
-------
appropriateness of the receptors cannot be evaluated from the
standpoint of population risk.
5. CONCLUSIONS
The results of this conservative screening level risk
assessment are:
1. available site data show that there are no cancer
risks or the potential for non-cancer health
effects above regulatory levels of concern even
though conservative, theoretical .models estimate
exposures equal to or slightly above threshold
levels for potential non-cancer effects; and
2, the predominate source of the theoretical
exposures above threshold levels is CSC, not the
cement companies.
Region 6 arrives at the first conclusion for two reasons.
First, the models and exposure scenarios upon which the estimates
of risks and potential non-cancer health effects are theorized to
occur are, in our judgement, conservative. The experts who
reviewed this report also commented at length on the conservatism
associated with the risk assessment. Because the risk assessment
is conservative, actual risks and exposures are likely to be less
than the estimated risk and exposures. Given this conservatism
and the fact that the theoretical exposures of concern for .
antimony, cadmium, and mercury are in the "grey* or "borderline"
range (equal to or barely over the threshold), Region 6 cannot
presently justify the necessity for immediate regulatory action.
Secondly, actual measured concentrations of those
contaminants that result in exposures above threshold values
appear to be present in media at concentrations less than modeled
concentrations. Actual exposure to antimony (the contaminant
with the greatest exposure) in the Midlothian drinking water
supply system: equals 0.05 rather than 3 as presented in Section
3. Secondly, actual measured concentrations in soil of two of
the contaminants for which exposures are above threshold levels
(antimony and cadmium) are less than modeled concentrations in
the area north of CSC close to receptor locations Cl and C3. The
measured and modeled concentrations are compared in Table 2 below
along with background data. The fact that the measured
concentrations are less than the modeled concentrations is
particularly interesting given that CSC has been operating since
1975 (20 years to date) and TXZ has been burning waste derived
fuel since 1987 (9 years to date) and the risk assessment
considers emissions for 30 years.
E-59
-------
Table 2 Comparison of Modeled and Measured Concentrations
COMTMR
Aatiaony
Cadmium
M«rcury
MOOELBO IOXL
COMC.
(MO/K9)
6.3
11 - 90
0.38
MEAftaUD1
(HO/KO)
<3
< 0.095 - 3.6
<1.0
tiOCAL KIC0UD
(MO/K8)
<1 - 3.8
0,01 - 7
<0.01 - 4.6
Finally, Region 6 can currently find no basis for federal
regulatory action in the Midlothian area in response to a mercury
HQ equal to one. There is no basis for action because of the
conservatism and uncertainty associated with the risk assessment
methodology and because the measured media concentrations of
mercury are less than or equal to local and U.S. background
concentrations of mercury. Region 6 is currently unable to judge
the viability of estimated mercury exposures as represented by
HQs greater than or equal to one due to uncertainties in the.
methodology. In addition, TNRCC has stated in its Critical'
Evaluation that concentrations of mercury in.the Midlothian area
are equal to or lower than local and U.S. background levels.
Some citizens and organizations may still be concerned with
emissions from the four industries subject to this study despite
the fact that the models and exposure scenarios used in this
analysis are conservative and Region «'s determination that
actual cancer risks and non-cancer health effects are below
regulatory levels of concern. Furthermore, it may be of interest
to local and state governmental organizations to identify the
predominate source of theoretical risks from the four major
industries in the area.
The predominate sources of risk from the four industries can
be evaluated by comparing the emission rates and unit combined
deposition and air concentrations associated .with each facility.
The unit combined deposition and air concentrations associated
with each emission source are compared in Table 3 for Point C3.
Emission rates are compared in Table 4.
tobtakwdtornTNiCC*race* Qth*B*Mian<*tl»f*i**Ultrrmx
-------
Table 3 Comparison of Unit Deposition Rates and Air
Concentrations
FACILITY
CSC Pugitiv««
CSC B*9fcou«« A
CSC Ba 9*e I
g/»«o
30.8
0.320
0.080
0.078
0.005
0.012
0.001
DHIT JUI CO«C.
(«f/«») pur X
9/«*e
18
0.37
0.06
O.QS3
o.ooc
0.013
0.001
As not8Ki in Table 3 above, the deposition rate of
contaminants from CSC are at least an order of magnitude greater
than the contaminant deposition rate, associated with the cement
kilns. CSC's fugitive emissions overwhelm all other deposition
rates by two to three orders of magnitude while Holnam's and
NTCC's deposition rates at this location are almost negligible.
TXX's deposition rate at this location is greater than Holnam's
and NTCC's, yet still significantly less than CSC's deposition
rates.
Likewise, the unit air concentrations associated with
emissions from CSC are at least 100 times greater than those
associated with NTCC and Holnam, The level of CSC's baghouse
emissions on contaminant air concentrations at this location is
six times the level of TXZ, the next most significant source.
The level of CSC's fugitive emissions is 1000 time% the level
TXX's emissions.
A comparison of the emission rates between the four
facilities in Table 4 again shows that CSC's emissions of
antimony and cadmium dominate that of the other facilities.
CSC's estimated emissions of antimony are 186 times that of TXI
and CSC's emissions of cadmium are almost five times that of TXZ.
Thus, it is clear that the majority of the potential for
theoretical noncancer health effects associated with antimony and
cadmium result from CSC, not the cement manufacturing facilities.
E-61
-------
Tabl« 4 Comparison of Emission Rates
Coaatitaaat
•
Aatiaoay
Arsaaie
l«*ia*
BavyUiw
CadaUn
CaraaUaa VI
I*a4
Mannury
Hiokal
•ilvwr
ThjUli**
IiM
Caaparral.
Istiaata4
l«pr«*aafeati
»• («/••«)
2.971-02
I. 191-04
HA
•A
3.021-03
3.791-04
S. 151-02
1.0«B«OS
T.MI-03
•A
•A
S.9H-OX
vice
latimataa
K*pr**«atat
iv« (9/s«e>
9.09B-05
1.071-09
2. 6 SI-OS
1.77I-0«
3.181-04
2. 6 SI-OS
4.171-03
4.C7I-04
2.7II-OS
•.9IB-OS
t.2«I-OS
S. 431-0*
TZZ
I«tiiut«d
••pr«*«stat
ir«
-------
DO NOT QUOTE OR CITE
CASE STUDY C
BIOCRUDE CASE STUDY
FOR RCRA LISTING
Section 1 of 2
Regional Risk Characterization Case Study
Risk Characterization Colloquium
Series C-2
OSWER and EPA Regions
August! &2, 1996
Dallas, Texas
E-63
-------
E-64
-------
w
ON
U\
Case Study of Risk Assessment for RCRA
Biocrude Waste Listing Decision
Prepared by
Office of Solid Waste
August 1-2,1996
-------
Background
• RCRA requires that EPA identify wastes that must be managed as
"hazardous wastes"
• Hazardous wastes are those that either:
• Exhibit a hazardous characteristic (e.g., ignitability, corrosivity); or
• Are individually "listed" as hazardous for waste-specific properties.
S (The listing applies nationally; delistings are site-specific).
• RCRA identifies wastes that must be considered for listing.
• The risk assessment is a primary component of a listing determination.
However, other factors are also considered (e.g., coverage by other programs,
damage cases, etc.).
• This document provides an overview of a risk assessment conducted in
support of a listing decision for the hypothetical residual, Biocrude waste.
-------
£
Summary of Analytic Approach
OSW's analysis of Biocrude waste includes evaluation of:
• intrinsic hazard of constituents present in the waste;
• fate and mobility of these chemicals;
• likely exposure routes to potential receptors; and
• plausible waste management practices and waste stream characteristics
(from industry survey data).
An initial screening analysis was done to provide a bounding estimate
of potential risk.
Central tendency and high-end risks were estimated for constituents/
management practices that did not bound out (i.e., cancer risk
> 1x10-6 or HQ>1).
-------
w
Summary of Results
The risk assessment indicated a high-end risk of 3 x 10-5 to consumers of
groundwater due to benzene leaching from landfills.
Land treatment presented high-end cancer risks of > 1x10-6 to adult
residents and home gardeners from polynuclear aromatic hydrocarbons (PAHs).
The central tendency estimates did not show significant risk for any exposure
scenario.
Estimated risks to a subsistence farmer were as great as 7 x 10-3. However,
we believe this is a significant overestimation of risk (3 orders of magnitude)
due to use of highly uncertain bioconcentration factors for PAHs. We are
continuing to investigate biotransfer of PAHs.
Risks to aquatic and terrestrial ecological receptors were below levels of concern.
-------
w
ON
vO
Description of the Biocrude Wastestream
Information on waste composition and management was collected through
a RCRA 3007 survey of all of the 120 facilities generating biocrude.
Biocrude waste is generated from the storage of virgin biocrude when basic
sediment, water and biocrude oils settle in the bottom of storage tanks.
About 22,000 MT of biocrude waste were generated in the survey year (1991).
Management scenarios chosen for risk assessment were land treatment
units (LTU) and landfills — the most common managementpractices for
this waste.
Constituents of primary concern based on bounding estimates are benzene and
PAHs for human health and cadmium for ecological risk. Over 90 constituents
were analyzed.
-------
Hazard Identification and Health Effects Assessment
OSW relies largely on standard Agency positions and documents for many
aspects of its risk assessments. This enhances consistency and
provides for efficient use of OSW's resources.
• Two key examples are the IRIS data base and the "Exposure Factors
Handbook."
To the extent that these Agency sources are deficient, OSW's assessments
will have the same deficiencies.
-------
\iKf
Hazard Identification and Health Effects Assessment
• The human health toxicity benchmarks for benzene are provided in IRIS.
• The human health benchmarks used for PAH are based on the Provisional
Guidance for.Quantitative Risk Assessment of PAHs (EPA, 1993) which
provides an "estimated ordering of potential potencies" of PAHs.
w . .
^ • The potency of BAP is indexed at one. Relative potency of each PAH
is calculated as a ratio to BAP. These values are for oral exposures only.
• Trimethylbenzene was initially identified as a potential constituent of
concern based on a reference dose (RfD) that had not been peer reviewed.
However, based on a peer reviewed alternative RfD provided by ORD,
trimethylbenzene was determined not to present risks > 1 x 10-6.
-------
Exposure Assessment Methodology
Pathways and Receptors
Pathways considered for land treatment units were inhalation, soil ingestion,
consumption of contaminated beef, milk, above- and below-ground produce,
and fish.
Ingestion of well water was evaluated for landfills.
Cancer risks were added within like pathways. Non-cancer effects on the
same same system or organ were added.
Groundwater and non-groundwater pathways were not added because
they involved different management units and different receptors.
Receptors included nearby residents, subsistence farmers, subsistence and
recreational fishers, and home gardeners.
-------
Exposure Assessment Methodology (Cont.)
Models and Input Parameters
• Existing Agency models were used for fate and transport (e.g., USLE for soil
erosion/run-off, ISC3 for air dispersion, EPACMPT for groundwater).
& • Standard exposure factors were used for dietary consumption rates and
fractions contaminated (i.e., Exposure Factors Handbook).
• Input parameters included waste and facility specific data from the
industry survey (e.g., on-site unit size, waste quantity, constituent
concentration) and data from nationwide survey sources (e.g., soil property,
distance to receptors, meteorologic conditions, size of off-site units).
-------
' <••*
Exposure Assessment Methodology (Cont.)
Bounding
• All waste stream, unit, fate & transport, and exposure values were set at 90th
percentile (or 1 Oth, if appropriate) when a statistical distribution was
available; maximum values were used when only a range was available.
w
^ • Results were evaluated to determine which scenarios demonstrated no
potential cancer risk > 1 x 10-6 and/or noncancer risks > an HQ of 1:
Central Tendency
• Central tendency was estimated for each management practice/constituent/
pathway combination that did not bound out.
• Values for waste stream and management unit characteristics, environmental
fate and transport properties, and exposure scenarios were set at median values
-------
Exposure Assessment Methodology (Cont.)
Ul
High-End
• Due to data limitations (e.g., limited # of waste samples) a deterministic approach
was used for this risk assessment.
• From a sensitivity analysis of 15 variables, six were picked for setting at high-end:
(90th percentile) LTU size; waste quantity; constituent concentration; meteorologic
conditions; distance to receptor; and exposure duration.
• The 2 most sensitive of these 6 were set at the 90th percentile for each scenario.
• All other variables were set routinely at their central tendency values and run-off
controls were assumed absent or ineffective for high-end.
-------
Risk Characterization
Final Risk Estimates
• Contaminated soil and groundwater were the two pathways of concern.
Risks from air dispersion were negligible compared to soil erosion (> 2 orders
of magnitude).
2 • A high-end cancer risk of 3 x 10-5 from benzene was estimated for an adult
consuming groundwater contaminated by an off-site landfill. The two most
sensitive parameters for the landfill scenario were waste quantity and distance
to well.
• For the LTU, 5 to 6 PAHs posed high-end risks > 1 x. 10-6 for the home
gardener and resident. The double high-end variables were waste
quantity and duration of exposure.
-------
Risk Characterization (Cont.)
Final Risk Estimates
• Risks estimated to a subsistence farmer were as great as 7 x 10-3 but were
discounted due to uncertainty associated with BCFs for PAHs.
^
w • When all parameters were set at the 50th percentile, no individuals had
-•si
^ risks > to 1. x 10-6 or HQs > 1 for any management unit scenario.
• When runoff controls were assumed 100 percent efficient, no constituents
posed high-end risks > 1 x 10-6 or HQ > 1 for any management unit scenario.
Population Risk
• Population risks, estimated for adult residents and home gardeners, were neglible.
However, to date, OS W has not used population risk as a basis for decisions.
-------
oo
Uncertainties
Fate and Transport
• Use of the U$>LE model creates uncertainties for runoff/erosion modeling
• USLE predicts soil movement as a long-term average and therefore
doesn't address acute toxicity from storm events.
w • USLE assumes sheet flow rather than channel flow.
• The Sediment Delivery Equation uses a fixed set of delivery parameters (e.g.,
soil textures, watershed patterns, vegetative buffers, rainfall-runoff).
• The SDE was designed to estimate sediment yields to reservoirs and may not
be appropriate for LTU scenarios (e.g., slope shapes, flow assumptions and
other characteristics may differ).
Biodegradation of benzene in landfills wasn't considered because we don't have a
complete set of biodegradation rates.
-------
vo
Uncertainties (Cant.)
Exposure
• There is high uncertainty in the calculated plant uptake factors and
plant-to-animal BCFs for PAHs.
• No empirical data were found for PAH bioaccumulation in mammals;
the model uses Kow to predict transfer factors.
w *
Empirical data show that using Kow to predict bioconcentration in fish
overestimates fish tissue concentrations by several orders of magnitude.
Based on modeled BCFs, beef and dairy product ingestion pathways were
major contributors to cancer risk estimates for subsistence farmers.
Due to the high uncertainty associated with these BCF$, OS W does not
recommend using the subsistence farmer scenario to support the listing decision.
-------
Uncertainties (Cont.)
Waste Management Unit
• While runoff and erosion control practices are in place for some LTUs; we have
no data to evaluate their prevalence or effectiveness. Therefore, risk
estimates may be appropriate* underestimated, or overestimated.
Isolated Waste Stream
• Risks were assessed for the individual waste stream and do not reflect potential
cumulative risks from codisposal with other wastestreams although codisposal
is the norm.
-------
:.n •-•
Risk Assessment Strengths
• The listing was based on a large data collection effort involving all active
biocrude generators in the U.S. The data base was designed to be as
accurate and representative as possible.
• The assessment is based on/consistent with EPA's Risk Assessment Policy.
£ • The assessment was externally peer reviewed and modified based on comments.
H-i " .
• Established EPA sources were used for tox data, exposure assumptions, etc.
• The most up-to-date modeling methodologies were used.
• Both internal and external experts were consulted in determining how best to
deal with uncertainties and data limitations.
• We continue to pursue solutions to remaining uncertainties.
-------
E-82
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DO NOT QUOTE OR CITE
CASE STUDY C
BIOCRUDE CASE STUDY
FOR RCRA LISTING
Section 2 of 2
Regional Risk Characterization Case Study
Risk Characterization Colloquium
Series C-2
OSWER and EPA Regions
August 1 & 2, 1996
Dallas, Texas
E-83
-------
Hypothetical Ecological Risk Assessment
of Cadmium in Biocrude Waste
Office of Solid Waste
August 1-2,1996
-------
Ecological risks from biocrude are low (i.e., hazard
quotients are more than two orders of magnitude less
than 1) based on comparison of media concentrations
with ecological benchmarks
Strengths of analysis
- Incorporates a broad range of receptors
- Includes both terrestrial and fresh water ecosystems
- Coordinated with ORD and conducted comprehensive
literature review to develop benchmarks
-------
ary (cont'd)
oo
Uncertainties
- Use of individual-level benchmarks as surrogates for
ecosystem protection
- Limited toxicity data for some receptors (e~
- Representativeness of generic ecosystems and types of
receptors
- Use of benchmarks that represent statistical significance
rather than biological significance
- Relationship of receptor home ranges with waste
management unit sizes
- Exposure concentration estimated as long-term average,
which may be longer than lifespan for some receptors
-------
uction
m
oo
Hypothetical case study
Uses concentrations in environmental media
calculated in the human health analysis to identify
potential adverse ecological effects
Focuses solely on cadmium, actual analysis would
look at all constituents
-------
em Formulation Phase
w
oo
oo
Objective of this phase is to establish the goals,
breadth, and focus of the assessment
In this phase, focused on four areas:
- Selection of the generic ecosystems
- Categories of ecological receptors
- Receptor identification and the generic ecosystem
- Stressor characterization
From these, formed conceptual model for the generic
ecosystems
-------
ic Ecosystems
WMUs can be located in virtually any ecosystem
Screening level analysis at national level
Generic ecosystem allows for broad coverage
Terrestrial and fresh-water ecosystems evaluated
-------
trial Ecosystem
• Partially forested, consisting of both coniferous and
deciduous trees, characterized by sufficient
vegetation to support a variety of wildlife
g • Applies broadly to many areas throughout U.S.
where biocrude could be managed
• Variety of species associated with partially forested
areas
-------
Water Ecosystem
• Represents large lakes throughout the continental
US.
• Represents a broad range of aquatic species
§ • Includes both littoral zone and limnetic zone
• Includes sediment-based ecosystems in the littoral
zone
-------
tor Identification and the Generic
"ystem
Evaluated hierarchical approaches and representative
trophic level approaches
Selected combination of approaches, receptors
selected based on:
- Significance in ecosystem
- Position along a continuum of trophic levels
- Representativeness of likely exposure pathways
Objective to be protective at ecosystem level
-------
tors and the Generic Terrestrial
rystem
Primary Producers
- Vascular, terrestrial plants
- Preferred data on different genera of plants
- Limited plant toxicity data
- Any species of plant acceptable
Wildlife species across trophic levels that do not live
in the soil
- Lowest trophic levels feed primarily on vegetation, included
meadow vole, cottontail rabbit, and whitetail deer
-------
tors and the Generic Terrestrial
^ystem (cont'd)
Wildlife species across trophic levels that do not live
in the soil (cont'd)
- Second trophic level included species that feed primarily on
insects and soil fauna, included the short-tail shrew and
American woodcock
- Middle trophic levels included opportunistic feeders
including the deer mouse, raccoon, and robin
- Top level predators included the red fox, red-tailed hawk,
and American kestrel
-------
vo
tors and the Generic Terrestrial
Astern (cont'd)
Wildlife species that live in intimate contact with soil
- Selection guided by two principles-
organisms that use resource in similar way, have similar
diets
- taxonomic groupings are useful indicators of species
sensitivity
- Eight types of soil organisms selected including nematodes,
soil mites, arthropods, and molluscs
-------
w
tors and the Generic fresh Water
"ystem
Developed both limnetic zone and littoral zone
ecosystems
Primary producers
- Important for functioning of the ecosystem
- Algae and vascular plants
Sediment community (littoral zone only)
- Key component of aquatic food web
- Species used for AWQC were used for sediment community
-------
tors and the Generic fresh Water
ystem (cont'd)
Fish and aquatic invertebrates
- Selected organisms should be protective of a variety of
species
- Range of species used for the development of national water
quality criteria were included
- Range included zooplankton, small fish, and larger
piscivorous fish
Mammals
- Predatory mammals found in freshwater settings
- Mink and river otter
-------
w
V!D
oo
tors and the Generic Fresh Water
wystem (cont'd)
Birds
- Species were selected that rely heavily on fish or aquatic
invertebrates
- Fish dependent species include eagle, great blue heron,
osprey, and kingfisher
- Mallard duck and lesser scaup account for species that
consume lower invertebrates
- Spotted sandpiper included to represent higher end
exposure to sediment dwellers
-------
or Characterization
w
Jo
vo
Cadmium has been implicated as the cause of
deleterious effects on fish and wildlife
Numerous laboratory studies have documented
effects of cadmium toxicity on mammals and birds
Studies have shown that cadmium bioconcentrates in
aquatic biota
Studies on the bioaccumulation/ bioconcentration of
cadmium in terrestrial species are currently being
reviewed
-------
sis Phase
w
H»
8
Development of ecotoxicological benchmarks
Exposure parameters for receptors
Discussion of the spatial and temporal distribution of
contaminant and receptors
-------
lopment of Ecotoxico logica I
marks
Reflect level of biological organization assessed
Ensure viability of wildlife and ecosystem
Specific to receptor and exposure route of concern
Generally, used a "No Effects Level" approach
Categorized benchmarks as adequate, provisional,
or interim, based upon the quality of the study and
the sufficiency of the toxicity dataset
-------
marks for Receptors in Terrestrial
ystem
Plants
- Adverse effects ranged from percent yield to root length
- Rank order benchmarks and then estimated 10th percentile
level
- Categorized as provisional
Mammals
- No suitable studies for species of interest
- Extrapolated from surrogate species
- Categorized as adequate
-------
hmarks for Receptors in Terrestrial
ystem(cont'd)
• Birds
- No suitable studies for species of interest
- Extrapolated from surrogate species using cross-species
scaling algorithms
i
§ - Categorized as adequate
• Soil Community
- Based on the RIVM methodology which assumes"
- NOEC and LOEC are distributed logistically
-------
-
s
provisional
-------
w
g
hmarksfor Receptors in fresh Water
ystem
Plants
Used either a NOEC or LOEC for vascular aquatic plants c
an effective concentration for freshwater algae
Benchmark based on reduced population growth rate
Categorized as interim
Sediment community
Based on the ER-L and ER-M methodology used by NOAy
Based on large amount of date, however large number of
samples from marine water databases
Categorized as interim
-------
hmarks for Receptors in Fresh Water
sllr
ystem (cont'd)
Fish and aquatic invertebrates
Based on the Final Chronic Value (FCV) developed for the
AWC
Categorized as adequate
Mammals
No suitable studies for species of interest
Extrapolated from surrogate species
Categorized adequate
-------
hmarksfor Receptors in Fresh Water
ystem (cont'd)
Birds
Data available on the reproductive and developmental
effects
Applied allometric scaling techniques to develop benchnu
Categorized adequate
-------
w
sure Parameters for Ecological
ptors
Sources include the Wildlife Exposure Factors
Handbook, the Great Lakes Water Quality Initiative, or
other Agency works
Parameters include body weight, soil and drinking
water ingestion rates, food intake, and dietary
preferences
-------
ure Concentrations in Media
• Analysis used concentrations in media of concern
predicted for human health risk
• Concentrations predicted in media of concern:
Water: 2. E- 6 mg/L
Soil: 2.2E-* mg/kg
Sediment: . E- mg/kg
-------
ml and Temporal Distribution of
ptors and Stressor
Consider home ranges of ecological receptors
Many organisms had ranges smaller than large LAU
Other organisms evaluated at range of large agricultural
field
Did not adjust percent of contaminated food ingested
Consider relationships between life spans and
exposure time
Performed sensitivity analyses with shorter exposure
periods to evaluate impacts
Negligible impact on results
-------
haracterization
• Ecological risks from cadmium in biocrude waste are
low
• Hazard quotients were two or more orders of
§ magnitude lower than the level of concern
• Numerous uncertainties associated with the
ecological assessment of biocrude waste
-------
haracterization (cont'd)
• Strengths of analysis
Incorporates a broad range of receptors
Evaluates both terrestrial and fresh water ecosystems that
£ are representative of many areas in U.S.
Evaluated both flora and fauna
Coordinated with ORD and conducted comprehensive
literature review to develop benchmarks
Developed benchmarks for several trophic levels
-------
haracterization (cont'd)
• Key uncertainties associated with the Problem
Formulation Phase:
Inference of ecosystem protection
2 Selection of No Effects vs. Lowest Effects levels
i—»
Use of generic ecosystems
Representation of trophic levels with single species
Bioaccumulation of cadmium in higher terrestrial organisi
-------
w
haracterization (cont'd)
Key uncertainties associated with the Analysis Phase:
Selection of receptors
Biological vs. statistical significance
Laboratory to field extrapolations
Interspecies uncertainty
Terrestrial territory sizes
-------
I—»
l-»
<~n
haracterization (cont'd)
• Other areas of uncertainty
Approach for soil community
Evaluation of toxicity to soil fauna
Effects of soil characteristics on toxicity
Use of category approach (i.e., adequate, provisional, and
interim)
Reliance on population-type effects
Terrestrial species dietary fractions and food item categori
-------
E-116
-------
DO NOT QUOTE OR CITE
CASE STUDY C
BIOCRUDE CASE STUDY
FOR RCRA LISTING
Regional Risk Characterization Case Study
Risk Characterization Colloquium
Series C-l
OSWER and EPA Regions
June 6 & 7,1996
Washington, D. C.
E-117
-------
E-118
-------
RISK CHARACTERIZATION ISSUES:
BIOCRUDE CASE STUDY FOR RCRA LISTING
General Background.
The Resource Conservation and Recovery Act (RCRA) requires Ac U.S. Environmental
Protection Agency (EPA) to develop a regulatory framework to identify those wastes that must
be managed as "hazardous wastes". Under the RCRA regulations a waste is considered to be
hazardous and is subject to regulation as such'ifit 1) exhibits one of four hazardous
characteristics: ignitabflhy, corrosivity, reactivity, or tenacity or 2) has been designated as
hazardous and fisted as such in the regulations. One of the criteria to be considered for listing a
waste as hazardous is that the waste is capable of posing a siibstantial present or potential hazard
*» tm«na.i h~tfh nr th* *miimfimiH* tiA.n mmrninnrly tr, ttf f
Section 3001(eX2) of RCRA requires that EPA determine whether biocnide waste should be
ninia Issnff
To focus and encourage discussion on risk characterization issues, OSW staff prepared a
dr*ft paper containing a hypothetical case study for a RCRA hazardous waste listing
for hiocmde. Thg rang Bftufy ^t-ff?ntidflrfd t friffffitif' lirir'UBK'nfiiiTKrnt fi?f
Hazarious Waste IJstingDeternmiatioiis. KisanHihimedu assessment designed to dete
whether certain specified wastes shoukl be fisted as hazardous.
General Stntctnre and Content-
The case study characterization is written for several levels of audience, up to and
including risk managers and deciskjn^nakers. It is written to clearly identify the scope and focus
f>rt>*u*nt $ aimitmry pf th* "rff COTKhinO"^ ««ri rffJfflTjt-f thg Vty ltmit«tion«
uncertainties of the estimates of risk.
The basefine risk assessment for a hazardous waste Hstmg determination draws upon a
signtfinant amomit of fiuaBty-gpecifie mfhrnMtJon together wMi general information not
specifically linked to the waste stream or industiy under study. Facffiry-specific information
distributions of 'die characteristics of the waste (e.g., constituents,
vohmes), sad waste disposal pnctices(e.g^ landfill, tented tanks, land treatment). Information
of a more general nature inrfo!rt*f distributions of meteorological condttMwi; types of receptors
(human and ecological) and tiwr locations relative to a waste management unit, sofl
characteristics, and exposure durations and frequencies.
OSW does not currently prepare a separate document or chapter of a document that
includes all elements of a risk characterization. Instead, tins type of information is captured in
briefing packages for discussion whh the risk nianager/decisioiHnaker. Also, as this type of
E-119
-------
analysis support* a regulatory decision, OSW presents a summary of the risk characterization in
the Federal Register preambles of proposed and final rules.
Findings and Uncertainties.
Several major areas of uncertainty in both the human healtfa and ecological assessments
are presented for the case study. These were selected because of their agntfiMmr* for the OSW
to recc^nmend a hazardous waste listing decision for the biocrude These areas are:
-thetransfonnationofwasteamstituerjtsbybiodegrada^
lacfr of sufficient datu *4nrfirt*?"**i*g the rate ixrpfftintf for those
- the presence and effectiveness of run-on/run-on control measures at land'treatment units
receiving biocrude waste
-thebrotransferfcctorsforPAHs
- the use of individual-level benchmarks to infer ecosystem protection
; of generk ecosystems and potential suites of
with these ecosystems
- the use ofbenchmarks that represent statistical sigmfi
-------
Sample Case Study
RCRA Biocrude Waste Listing Decision
Prepared by
Office of Solid Waste
U.S.EPA
April 1996
E-121
-------
E-122
-------
Human Health Risk Assessment for Bioerade Waste
1. Introduction
Background
The Resource Conservation and Recovery Act (RCRA) required the U.S. Environmental
Protection Agency .(EPA) to develop a regulatory framework to identify those wastes that must
be managed as "hazardous wastes". Under the RCRA regulations a waste is considered to be
hazardous and is subject to regulation as such if it 1) exhibits one of four hazardous
characteristics; igmtabQity, cont>srvity, reactivity or toxicity or 2) has been designated as
hazardous and listed a such in the regulations. Section 3001(eX2) of RCRA requires that EPA
determine whether biocrude waste should be fisted as a regulated hazardous waste. The purpose
of this document is to summarize the risk aiWR'Mmypit conducted as a basin for tHf hazardous
Sammarv of Analytic Approach
In determining whether biocrude waste meet the criteria fbr a hazardous fisting, the
Agency evaluated the potential toxicity mid intrinsic hazard of constituents pre.wit in the waste.
the fate and mobility of these chemicals, the fiketjr exposure routes, ">j the current waste
management practices to sdect hypothetical itx*ptori The assessment includes an initial
screening analysis to provide a bounding estimate of potential tiak followed by estimation of
central tendency and high-end risk for those (xmsritiienta/waste management practices that did not
hound out (Le., cancer risk of less man x Iff* or hazard quotient less than 1). The scenarios (Le.,
receptors) included in the risk assessment inchide adiitefeaid^nt, home gardener, recxeaticiial
fisher, subsist gncft fisher, subsistence I^'MW, ff"d cftinnitnCTfi of groundwater.
Summary of Results
Risk estimates indicate that biocrude waste, when managed m land treatment units with no
runoff control, may pose an individual cancer risk greater than 1 x 10* for hypothetical, nearby
adult residents and home gardeners from human exposure to polynudear aromatic hydrocarbons
(PAHS).
nm*
.
UTtil tft iiili'f rriHitflinliifrfH y*1*, PAH ""^ ilMr* ******* *«* **> •? gr^f ii ^ y 1 «T» For an adult
resident who is- assumed to ingest contaminated sofl and mhale contaminated air, PAH risks were
estimated to be as great as 9 xlO"5. IB addition, the Agency estimated a high-end risk of 3 x 10*
to omsumers of grwindwaterirom benzene resutengf^ The
central tendency estimates did not show significantrisk for any exposure scenario. Theresuhsfor
on- and off-she land treatment and landnHs are presented m Table 1.
Risks .estimated to a subsistence fanner were as great as 7 xlO*. However, the OSW
recommends not using the subsistence fanner scenario to support the listing determination
because of the high uncertainty associated with the bioconcenteatkn factors for PAHs, the onh/
E-123
-------
const
thuents of concern. In conducting the subsistence fanner risk assessment, the Agency
determined that there is high uncertainty in the calculated plam-4o-*nimal (primarily beef and dairy
cattle) bic7
3B-7
7««7
2K-8
21-«
1E-5
1X-S
1B-5
5E-5
1E-6
tt-5
off ait* ur
ct
B
91-7
71-7
11-5.
31-6
6E-8
«-«
61-6
51-6.
61-6
61-5
41-7
tt-S
132.0
37.0
23.8
331.0
76.8
230.0
49.0
27.0
•1,200.0
110.0
52.0
« * *
* • »
• • *.
27.0
4 of 4
1 of 4
1 of 4
1 of 4
4 of 4
Waste ChuractarizAtion (Cone. Mg/X>)
Avtr 1 Hioh 1 Latr 1 # of pt«
GrottnoVatcr
Benzen*
41-7
3X-S
0.68 1 1.7 1 0.032 1 S Of 6 1
E-124
-------
2. Summary of Hazard Identification and Health Effects Assessment
The human health benchmarks used for PAH in biocnide waste are based on the data
provided in the Provisional Guidance for Quantitative Risk Assessment ofPorycyclic Aromatic
Hydrocarbons (U.S. EPA; 1993). This document provides an "ffftirmrtrd ordering of potential
potencies" of PAH. In deriving the potency for each PAH relative the benzo(a)pyrene (B APX it
Is assumed that the dose-response carves were aiimUffbw that ft wouM take larger quantities of
otr^ PAH to induce a tumor response eqirivalent to th^ The relative potency of each
PAH is calculated as the ratio of the estimated transition rates with trw potency of BAP indexed
asl. These values are intended only for the evaluation of risk due to oral exposures. The
following table presents the gTrirrutfnd order of potencies for die constituents of concern for
biocnide waste.
Table 2. Eftinuted Order of Potential Potende* of Selected PAH
JNU
V*JU]|)VUIM
Benzo(a)pyreue
BenzCa^anthranfnr
-i <\ fit twin: lu
Benzoflriflouranthene
^ *
Chrysene
Indeno[l^
-------
and entrapped biocrude oils settle in the bottom of storage tanks. A storage tank is drained for
inspection and sediment removalon avenge once every 10 yean. The results of EPA's industry
survey for this fisting proposal showed that 22,000 MT of biooude waste were generated in the
survey year. The management scenarios selected for risk assessment included actual disposal
practices (on- pM off-site land treatment and off-site non-hazardous waste landfills).
4. Sammary of Exposure Asscssmoit Methodology
To assess exposure from land treatment units, both olrect and mdirect exposure pathways
were evahiated These mclude tnhalatio^ ingestion of sofl^
of contaminated beeC milk, above- tad below gro^ produce, tad fi^ The receptora (scenarios)
modeled for exposures were adult residents, subsistence farmers, siAsistencefishen^ home
gardeners, and recreational fishers.
Bounding
Because biocrude wastes are so complex in terms of composhion and pathways of
exposure, $nct **v& tryfir*^ fr»inM« hfihh riricii WCTC analyzed to provide afroiifi
-------
assumed to be collocated at the point of maximum exposure. The exposure duration was set at
the high end value of 30 years. Similar assumptions were made for both onshe waste treatment
facilities and offiote treatment facilities. The differences in the assumptions included the
characteristics of the management units (Le., area) and the waste quantity disposed of in it
Groundwater Pathway
For the bounding analysis, die leachate concentration of each ccnsthuent was set to the
maximum value measured for that constituent using the Toxfcfy Characteristic Leaching
Procedure (TCLP). The contananantconcentratioBs at the receptor d^
jstng the EPA Composite Model for LeacoateMigration with Transfbm
(EPACMTP). EPACMTP
leaching from land disposal unto. Waste streams and waste constituents of potential concern are
identified by comparing the model predicted exposure concentration to regulatory maximum
level* (MO A) and heahhAaacd concentiatkaa levda (HBNa) to det
termne
the expected contammant concentration exceeds the MCL or HBN value,
The waste unit area, infihration rate, waste quantity, landfill waste fraction and waste
concentration were set to their 90th percentue values, and the receptor wefl was placed on the
phmieccnteriine, at the 10th penxntOe of the down gradient dist^^ The depth of the wett was
also set to the lOthperceotile value, Otiier parameters were set to &effniedkn values, Abo,
source depletion was not assumed in the bounding analysis (Le., the rdease of the constituent was
modeled as a pulse with constant concentration equal to the nuodnaum measured TCLP
concentration for each constituent). To determine exceedences of HBN and/or MCL vahies, the
peak receptor wdl concentration was used for both carcinogenic and }xm-carcinoge0ic
constituents'
Central Tendency Estimates
Central tendency was estimated far each management pnu»c«/constituent/pathway
combination that did not bound out Parameter vahies for waste stream characteristics,
management unit characteristics, environniem^ n^ and tnmsport properties, and exposure
scenarios were simultaneously set at median values (50th percentile).
Non-growtdwater Pathway
AD waste stream and watershed characteristics were set at the 50th percentile for central
tendency estimates. Biodcgradation of PAH in the land treatment unit was incorporated in these
equations.
E-127
-------
Groundwater Pathway
All parameters were set to their median vahic. For central tendency, it is assumed that
each constituent mjtiiHy leaches at a concCTtfitiffti g*w fry tttp Varchatc sinvjlations can be used
to estimate the exposure (or risk) distributing However, the value rfa Monte Car^
limited unless adMmt^ ^itn are available to characterize the tnnpc of the distributions of input
vahies used to estimate risk. Diie to date hinHations, a detennimso^ approach was f^
assessment. For this assessment, high end is defined as those two variables modeled that, when
set at 90th percentfle vahies, pose the highest risk of afl possible combinations of any two
variables.
Nan-grounctoaterPatiHKy
The she variables selected for setting at the 90th percentite when performing high-end
modrfmg were chosen based on m sensitivity analysis of approximately 15 variables. (Table 3)
Once it was apparent that six variables were consistenth; me moat sensitive, afl other variables
were set routinely at their central tendency values. The six most sensitive variables were waste
\ scce, waste quantity managed, constituent concentration, meteorologic
nditions, distances to receptor, and exposure duration. Constituent concentrations used for
bounding and high-end analysis were not statisti<^distributions.Rjdier, the average
concentrations measured across samples were used for the central tendency, and the inaxmium
measured concentration across samples was used for bounding and high-end analyses. For the
evaluation of off-she land treatment units the distribution of quantities of waste and areas of land
treatment units accepting btocrude waste were used.
E-128
-------
Table 3. Laad Tn *tmt if AmmvOaot
Parameter 1 SMfc Dercctitfe
Quantity", MTAr
Dcuuty , cfaiL
Bulk density cf soil', gfcm*
Tiffing depth, m
Total porosity, cnr/car
Air porosity, cnr/eor
Time of cafe, days
BioJe tji adrtron, tape
iiiijicniiBC, w
Avg. annoa! pncip., cnt/yr
Avg. annoal evap.. cm/yr
Am ammal moft cmArr
Avs-aonaliafltntiaxcm^r
FjJJllIjLJl^L^-l.- ' _.J.jtui_L JP/M
y*»a««BUBi %ngam» *j«i<«ai, urn
Wind Speed, 10%
Sovoc Area, or
38
U
12
020
0.32
0.17
365
AA^aW ^L^^^^^^k^tt^
^VIB p^tvmmpn
1,839
lOOthpereeDtile)
NA
MA
0^2
0.17
365
21
119.7
2173
I3X)
217
0.16
4.1
58,769
17
28.7
731
13
73
0.65
4.1
14,164 (10&%)
130.713 (90oi H)
r IT
NA-Not«pplicabk.
The Agenfiy TOnductcd
tgv^ of »"«tyy"^^"^i^^
PAH risks that were identified ft* land treatment toe of the m^ assumptions m the runoff
models far rdeases from land treatment units is that the unh does not have controls £brnm-on
and nm^ffwasten from precipitation. A ngnHkartportron of the predicted risk fijrAePAHs is
associated with contananated sofla washing off of the LTU into residential areas. PAH risks are
reduced below fisting levels of concern if no nmron^un-off is assuincxl (le., afl run-on is diverted
and afl nm-off collected). Risks due to air dispersion of contaminantt was negligible compared to
exposure from soil erosion.
Groundwater pathway
The high-end nsyty^ii.nt of gtoundwater was conducted by asagntng two parameters of
the model to their high-end values, Rrrt,»«eBsitivitytMlysuwasco*
most sensitive waste source, and receptor wefl parameters. This analysis was conducted by
individually varying the source and wefl location oarametcrs from the 50th to 90th percennTe
E-129
-------
values and nuking them in terms of the corresponding change in predicted receptor wdl
ttion. For the subsequent high-end groundwater impact analysis, the two most sensitive
WJIUXUUIU
parameters were to their high-end values, while toe reniaimng model parameters were all kept at
median values. The two most sensitive parametersfbrthelandfiflscaiario were waste quantity
and distance to wdL The grqundwater pathway anatysUdW not consider transformation of waste
constituents by biodegradation due to insufficient data characterizing the anaerobic
biodcgrmfiition of benzene ID groufldwaier.
4.0 Risk Characterization
Final Risk Estimates
The risk assessment results showed a high-end cancer risk of 3 xia5 due to benzene for
»n adult lymaiming gpypirftyft ff eftiftfliniii^yn*""1 v* flff-fite Imdffll For the oo-site land
treatment without runoff controls, 5 to 6 FAHs were estimated with tngh-end risks greater than 1
x 10^ forthehonie gardener and aduhreadem(rangingfix)m IxlO^to 5x10^. The double
h^b-end risk variables yielding the maximum risk were waste q^iantiry and duration of exposure,
set at their 90th percentBe values. When jflrwtranieters were set at their SO&percemilevahies,
there woe no indtvidual risks greater than or equal to 1 x 10*
For the off-she land treatniett without runoff controls 4 to 6 PAHi were estimated with
risks greater than 1x10* for the home gardener aadadoit resident The high-end risk variables
were maximum waste constituent (XMicentratkm and exposure duraticra (30 years). Where all
parametera were set at their 56th percentife values, no individoab had rials greater tiian or equal
to 1 x 10-*. Table 14 summarizes these resuhs, and Tables 1-10 (see section 1) show results by
exposure pathway for the double high-end variables yielding the highest risk.
When runoff was assumed controlled at 100 percent eflSciency, no constituents posed risks
greater than or equal to IzlO4. Howevtr, the Agency does not have a coinpleteunderstandmg
information of the existence and effectiveness of land treatment tmits at controlling releases
assodatedwithrun-o/run-off
EniosnreSeciiafiM
Ew potential exposure scenarios ate evaluated in the human heahh risk assessment: a
subsistence fiomer, subsistence fibber, recreational ISsh^ All
of sou*
Tift!f iliflfrr in thft ^Tft^^miimti' po^m*" oflVy diftiify intikft TnWft 1 prrajfittn 1hr ratfff ftf
consumption and die fraction contaminated of food, water and soO and the rates of inhalation of
polhited air for each of the five exposure scenarios.
E-130
-------
Tabb4,
Foodormcdiam
Beeffeft)
MUkdi/d/KDW/d)
FubteU)
Abovegtouad fruits
«ni«g(gDw*D
T>»t— • ,..l,.ll. J .MM
xtttcw ground veg
(8/dKww)
SoafmaAD
AirdrfAft
W«nr(Ud«y)
ExporaraSccauio
SateistaMc
Funer
Rite
57
181
NA
20
28
100
20
1.4
Fne.
CantuB.
1
1
NA
1
1
1
1
I
SabdrtOM*
Fitter
Bate
NA
NA
60
NA
NA
100
20
1.4
Fnc.
CdBtnu
NA
NA
1
NA
NA
1
1
1
£
G*
Bate
NA
NA
NA
20
28
100
20
1.4
tow
rdoMr
Fnc.
NA
NA
NA
0.4
0.4
1
1
1
BMX
r
Bate
NA
NA
30
NA
NA
100
20
1.4
•««fciM|
bter
Wim.
NA
NA
1
NA
NA
1
I
1
NA-Nottppbcibk
DW-DiywagfaL
Aflv»toesfiantbe£«jKMjireFo(aor»jyawftoo*(UAEPA, 1990).
Adttttfctddrtrt
Bate
NA
NA
NA
NA
NA
100
20
1.4
Fne,
CMtam.
NA
NA
NA
NA
NA
1
1
1
Exposure Pathways of Concern
Contaminated Soil
Human ingestion of aoO is a possible significant route of exposure for contamination
originating from a land treatment unit Constituents sorbed to particles in the surface soil or waste
matrix may be transported o£Mte through the process of erosioa. The amount of contaminant
transported to an off-site field depends on the amount of soil lost from the site, and the
physical/chemical properties of the constituents of concern among other fictora. The Universal Soil
Ix>ssEquatk»(USIJEi)wasappBedtobiocnid^
risk due to incidentallngestkm of contaminated soils. OflMte sous may also be contaminatfd by
deposition of contaminated air partkuiates and vapors. However, the contamination due to soil
erosion as predicted by the USLE was orders of magnitude greater mat die exposure predicted to
occur from air deposition. An ingestion rate of 100 ing/day for aduh receptor was assuinedfo^
receptors.
E-131
-------
Contaminated Groundwater
The groundwater pathway analysu csthimtfrt the groundwater exposure concentrations
iE frpfB rftfitf- "f ^vitff fxmgtH11**1** from thf ^^n** TTi*tM|g|Cfn<3Tt wit into the iRibsurficf , and
the subsequent late and transport of the constituents, through the vadose zone and underlying
saturated groundwater zone. . The exposure concentration is evaluated at the intake point of a
hypothetical groundwater drinking wen (Le^ feceptorwefl) located at a sjyechled distance fioffi the
down gradient edge ox the waste management unit.
Addittvity of Pathways
The exposures from the oral indirect pathways are combined for each scenario and
consthwnt. In the adult resident sceanio, expoaui^ from iiKadenttlsoflingestioa are not added to
any other pathway, fo the home glirdenw
•t*< bckw ground "figgftihteff and inr********* soil fngff"111 ffay»M be added together. The f*vf result
is a total oral exposure (dose) for each scenario and constituent Given these exposures, a
ogenic risk and, for Boncancer effects, a hazard quotient are calculated for each scenario and
each constituent To determine the risk due to the waste streani, the total risk of each constituent is
added together for each scenario. Exposures from the direct mnalatioflpatnway have not b^
added to those from oral, pathways. This is because the toxic effect from the inhalation route of
exposure may be different from the toxic effect from the oral i>atnwayscw to portal of entry effects.
Groundwater and oral indirect pathways were not added because l)dlD^9ent receptors are exposed
via these routes, flnn 7) for all oonsutuffnfii frtpt benrone, tuue-to-cxposureis ffflpimr^fifly fliflCTCTtf
(Le.,>100 years).
5. Population Risk
Population risks were estimated far the fbflowing subpopulan'ons: (1) adult residents and
home gardeners exposed to PAHs in biocrude wastes that are land treated, and (2) consumers of
ground water exposed to benzene in biocrude wastes that are land fitted. In estimating population
risks from exposure of home gardeners and adult residents to PAHs, EPA evahiated exposures in
which effective run-off controls were in place and exposures m which run-off occurs. Under
istanccs with effective run-off oonuols, home gardeners were estimated to be exposed by
: sofl, fruits, and vegetables
contammatfiri by direct deposition of PAH
-------
for up to 235 adult residents. For on-site land treatment, central tendency risks from PAHs in
biooude waste were 4 x 10* for up to 120 tome gardeners, ari^
For on-site land treatment of btocrude waste, central tendency risks from PAHs were 7 x 10"7 for up
to 76 home gardeners, and 2 x 10* for up to 200 adult residents.
For the groundwatereaposure pathway frnmtarttt^^
of people exposed to constituent concentrations above health-based levels (at the 10* level) for offi-
site landfills. The number of individuals exposed above healm-oasedleveb for benzene mbiocnide
waste is 17.
6. Uncertainties
Fate
Runoff/EraSUXlModeting. The ralnitofrn of mrtggftor anfl concertratiftn U a Iray atep hi edml^g
risks from biocrude waste constituents because this parameter serves as the fink between waste
disposal in the land treatment unit and exposure to off-site receptors. EPA used an adaptation of the
USLE to calculate the uumxatliaiion of constitiients at ah offiate receptor location from run-off from
a land treatment unit The general consensus is that thb approach b^ many drawbacks and can be
improved upon by using watershed models. Drawbacks of the USU£arjproachindude:
o The USLE is an empirical model that estimates the kwg^erm average annual sofl erosion
rates and does not predict off-site sofl loss or sediment defivered By averaging wet and dry
yean for a long-term average, die USLE loses the abffity to predict soil movement which
mosu> occurs during storm events, Abo, acute toxkaty depends on short term peaks, usually
following storm events. A long-term approach can't address acute toxicity.
o The sediment delivery ratio concept lumps many processes which aflect its estimation
including: soil textures, sofl profile, watershed geomorphology, vegetative buffers, and
characteristics of ramM-runoff events. Therefore, application of the sediment delivery
equation may be highly subject to uncertainty. In addition, this equation was primarily
derived to estimate •NJHP*"* yields to reservoirs in order to estimate their useful life or
dredging costs. Slope shapes, outlet conditions, flow assumption and other characteristics
used for this purpose may not be appropriately applied to land treatment unit scenarios.
Biadegradation of Benzene in Landftn Scenarios. Biodegradatkm may be a significant removal
process for benzene. However, because the data and parameters associated wimbiodegradationvary
over a wide range and may be Jnghrysite specific, they are highly uncertain. For these reasons, the
Agency developed a protocol for the determination of nationwide biodegradatkmntes, which was
published on June 15, 1983 (53 FR 22300). The protocol requires biodegradation date from six sites
that represent different regions of the country. To date, the Agency has not received a cornplete set
of biodegradation rates for benzene. Therefore, biodegradation is not considered directly in the
groundwater pathway analysis. However, EPA did evaluate Ac potential effect of biodegradation
E-133
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using available information and best estimates.
Exposure
PAH Biotransfsrfactors, AppJcaMe exposure p^^
of homegrown beef and milk, "igggtion of homegrown fivrts and ^egetabtef, incidental *
of soil, apd direct M^^on of VUJHMT and putKii^^r The total
vegetables that the subsistence farmer consumes is assumed to be contaminated.
In conducting the subsistence fanner risk assessment, the Agency, deternined that there is high
rtainry in the catouhttfld ptont-to-aiama] (primarily beef and dairy cattle) bioconcentration factors
the key constituents of concern fi-e^PAHs). No enipirical data were found for bioaccumulation
1* by this rou^ the modd uses phyac^
transfer factors. For fish, empirical data show that using K^, to predict Dioconcentration
fish tissue concentrations by several orders of magnitude. Based on these very high
predicted bioconcentratipn factors, the beef and dairy product ingestion pathways were major
contributors to cancer risk estimates for subsistence farmers. Because of die high uncertainty
associated with these btocc«*ntration factc^ho^vever, the OSW does nmrecommoidusmg the
subsistence fanner scenario to support tiie proposed Gstmgdt
The ingestion of contaminated food products is considered in the hwne gardener
get
One of the key factors affecting this pathway involves coiistituent specific biotiwisfe factors. The
PAH are very large compounds and are very h^ndrophcjbk; (have vtry high Kowvahies). For this
reason, the equations based on log KowO-e^Baesetal, 1984) used to estimate biotransfer factors
teiid to overestimate q^iiffflifiiiliitirMirf Several studies
how* jjjif
howcver, lor the rcmainmg Uutsfef factors high uncertainty ffiini'w Measured vahws lor
plant bfctransfer factors are available fir the cornpc«nds of cwicenimbic<«ioe waste (Simomch and
BBtes, 1994). There are no measured vahies for root vegetable factors. Kfiwhuncertamty remains
concerning bioaccumulation factors and several recent arn'des on the siibject are Mng evaluated for
iinpiuviiigtheestimatkmequatioMfa
analysis.
Waste Man«g«n«it Unit
Starmwaternmoff and erosion controi. The amount of contammant transported to the off-she sofl
and surface water body, depends on the amount of soil and nnioifkMt from tiie she and tiie physical
and chemical characteristics of the constituents. Control measures to reduce the transport of
potentially contnmimtrd nmoffand sofl/waste may diflBer from those estimated. Based on information
collected from the industry survey for this h^tmg, runoff control programs are ehiier not mpuMe at
allorareinpbKxbiitvaryincontroiEngninK^eroaon. Sonie land treatment imits may have dhches
around afl or part of the unh that play a part in runoff control; however, whether these dhches were
designed for the hiri ff^mifiit viyt or happen to be imny^itfid wirl* •"
-------
In the latter case, the ditches may i^ Therefore, this
risk assessment considered both ends of the spectnim of ramffand soft eroskn control Risks were
estinuilnd assuming no control, and assuming 100 percent control Depending oa actual ronoffmd
cootn^ practices for land treatt^^
or overestimated
E-135
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Hypothetical Ecological Risk Assessment for Cadmium in Biocrode Waste
Ecological Risk Assessment Case Study
1.0 Introduction
The purpose of this report is to provide a case study of OSWs approach to ecological risk
assessment, with an emphasis oathe risk characterization. Consequently, the report does not provide a
detailed analytic ecological risk assessment of constituents in biocrude. Instead, the report focuses on
the conceptual framework used to evaluate ecological risks firm (^diniam releases to ^environment
The conceptual framework is based on the methodology described in the Technical Support Document
for the Hazardous Waste Identification Rule: Risk Assessment jar Human and Ecological Receptors
(RTI.1995). OSW evaluated other constituents m biocrude wastes m a similar fashion.
Summary «f Analytic Approach. In addition to detennining whether biocrade waste may cause
adverse effects to b"mf" populations, OSW evaluated the potential fer hitvnui* q>»gt» t» <*•»«»
effects to ecological receptors. Unlike the human health assessment for which OSW bad data describing
potential receptors, OSW did not have any data c^scnl>mg the ecosystems and potential ecological
receptors near me waste management unit Tbns, the ecologica] assessment hKludedconsniJctiiig
generic freshwater and terrestrial ecosystems, identifymg a sm^ of receptors that may be associated wrtb
these ecosystems, and generating ecological benchmarks f« each of the receptors based on laboratory
and field studies. OSW compared the media couceuUations generated by the fate and transport modeling
for die human health analysis with the ecological berwhniaits to detennine whether bkxaude waste inay
resiihm adverse ecological hnpacts. This comparison is similar to the hazard quotient (HQ)
methodology used for human health non<^ OSW set an acceptable (HQ) for this
analysis at one.
SBfllBI§*Y °f ^*Mltti Companson of media concentrations generated by the. fate and transport
modeling with receptor-specific ecological benchmarks indicated that the ecological risks from cadmium
in biocrude waste are low. In all cases theHQ was two or more orders of magnitude less than the
acceptable level The results by ecological receptor are presented in Table 1.
Summary of Key fjnfcf rUlitfch Inherentto the analysis tnd the results are several key
uncertainties associated with the analysis. . M«|y of the. uncertamties are generic to most ecological
assessments ano* reflect a lack of data for eootogfcai assessments. Sonw of the key uncertainties that may
result in significant changes in the mterpretationof onrresuhs mchide:
• The use of mtividuai-levelbenchniarks to mfer ecosystem
• The representativeness of generic ecosystems and potential sntes of receptora associated with
these ecosystems;
• Relationship of terrestrial receptors territorial ranges with the size of waste management unhs;
and
• The use of benchmarks that represent statistical significance rather than benchmarks that
represent biological significance.
E-136
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Table 1
Results for Ecological Assessment of Biocrnde Waste
^^^
Mnk
Rhrarottar
BaM caste
Ospny
OrMtbhw heron
Mattaftf
Lascar scaup
KInglisiMr
AfM^i^Mfl •^•4w4a^^^B*?
HtffV^I QIM
BtfltlliC WmUlWaflfqf
Aquatic ocvantem.
Aquatic plants
ShOft*tsllsd snfwv
DMTRIOUM
MMdOWVOto
cJttfMli CCttOfNM
Itedfex
Raccoon
l^^^fA_ ^—ttA^ ^^^.^
VTTIRaFwMIMI O«Wr
RwMsMdtaMk
AnwriesnkMM
ttflh^Ah^^M AMftaWaAJaW
nonnvin DOmffmB
ARMffctti roWn
A^H^A^^k^i^ ^^^b^b^aW^k^iA*
Miwrmn wvOQGOdi
SoHtaura
TvnwMal ptanto
HQ for «oH
concMiDVDon
(untttam)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
5.4&OS
3.6E-OB
8J&OB
IJSBtff
1.1E47
2;0t07
4^B06
1.2&08
2.0&08
4.4&M
7.1&M
5.7E-07
Z2EOS
1.7E-05
(untthm)
1.3E-04
Z3E-0*
5.8E-05
8.4&OS
7.6E-08
7.4E-08
7.9E4B
1.0&04
3.0&07
6.9&09
NA
2.1E-03
1.1E48
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
HQ lOf ••OmMRt
JMKMM^BMBl^^^al^^M
cmnnuiBoon
(unMtes)
NA
NA
NA
NA
NA
NA
NA
NA
1.SE-07
NA
7.4E4S
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
E-137
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Because of these uncertainties, the Agency erred on die side of conservatism .when evaluating studies and
developing benchmarks. Even with conservative assumptions, no concentrations above levels of concent
were identified for cadmium in water, sediments, or soil.
The remainder of mis report provides a more detailed summary of OS Ws analysis and is organized
in three sections in accordance with EPA's Ecological Risk Assessment Framework as modified by the
Draft Proposed Guidelines for Ecological Risk Assessment (EPA, 1995): (1) Problem Formulation Phase,
which describes the generic ecosystems developed for HWIR, the categories of ecological receptors
considered, the generic trophic systems and the representative species assigned to them, and a stressor
characterization for cadmium (including bwaccumulation potential); (2) Analysis Phase, which describes
the development of ecotoxicological benchmarks for me receptors of concern, the exposure parameters
used to determine doses or exposure concentrations to the receptors, and the spatial (e.g^ home range)
and temporal (e.g., life-cycle) attributes of the ecological receptors with respect to cadmium exposures;
and (3) Risk Characterization, which describes the risk estimates for ecological receptors and provides a
discussion of the key areas of uncertainty and variability associated with the analysis. Although the
uncertainty section covers a variety of key issues, particular attention is focused on me areas that are
most problematic for the risk characterization.
241 Problem FonmdatfaHi Phase
There are three products that most be developed in the problem formulation phase of the ecological
risk assessment (EPA, 1995): (1) ecologically relevant assessment endpomts mat address management
goals, (2) ccmcepfcid models that describe the key rel^
assessment endpomts, and (3) an analysis plan. The assessment endpomts adopted for this hypothetical
case study are at the level of the ecosystem strorture and function and addhlonal assessment endpoints
were selected for the survival, reproduction, aulgrowm of wildlife population
communities (e.g^ soil community). The conceptual models that describe the relationship between
cadmium (the chemical stressor) and the assessment endpomts include: (1) the.generic ecosystems and
trophic structure assigned to those ecosystems aod (2) the fate and transport
characterize the exposure setting. The analysis plan evolves, in part, fioWthe stressor characterization
and includes measures of effect (formerly measurement endpoints), development of the exposure
scenarios (i.e., how exposures are occuring), and measures of ecosystem and receptor characteristics
such as life history characteristics! In abort, the anarysis plan shapes the selection of ecological receptors
to represent the generic trophic structure based on the availability of appropriate data and tools as well as
the compatibility with management goals (e.g^ consistency with fate and transport algorithms). The
following sections describe: (1) the generic ecosystems, (2) the eco-receptor categories, (3) the structure
of the generic trophic systems, including the identification of ecok>gical receptors, and (4) me stressor
characterization for cadmium.
2.1 Description of GcBerk£co«ysteiiM
A number of ecosystem types were considered to provide the context (i.e^ exposure setting or
habitat) for identifying ecological receptors of concern. As a starting point, OSW recognized mat, in
their simplest form, ecosystems may be thought of as emta aquatic or tenestriaL QSW also recognized
mat, ideally, an ecological risk assessment should be focused on a specific type of ecosystem (e.g^
wetlands) so that the appropriate ecological receptors are evaluated and the environmental chemistry
(e.g., pH of soil) is characterized. However, ecological risk assessment used to support a broad
E-138
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regulatory listing application requires & more generic approach. For example, waste management units
(WMUs)may be located in virtually any type of ecosystem across the country and, therefore, the
ecosystems should be broadly applicable throughout tee contiguous United States. Although this low
level of resolution reduces the applicability to any one site, a generic ecosystem approach allows a wide
variety of sites to be included. Perhaps more importantly, simple generic ecosystems may be
characterized using the same inputs and fete/transport algorithms developed to model the environmental
behavior and human health risks associated with contaminant releases from WMUs. Consequently, two
"generic" ecosystems were developed as basis for ecological risk assessment: a freshwater-based
ecosystem and-a teiTc&liial-based ecosystem.
The water-based ecosystem includes receptors associated with the limnetic zone (also pelagic zone)
typically defined as the region of open water beyond the .littoral zone (see below), and generally
characterized by a great abundance of phytoplaakton. This water-based scenario was included to
represent large lakes throughout the continental United States. The sediment-based ecosystem includes
receptors associated ivftfa tb« littoral ren«, typically defined at tfar »hallow, marginal region of a lake or
stream characterized by rooted vegetation. • Smaller freshwater lakes and streams would almost certainty
possess a relatively large littoral zone andsmall porids or streams may ctnsist entirely of a littoral zone.
The generic terrestrial ecosystem was designed as a partially forested ecosysban, consisting of both
coniferous and deciduous trees, characterized by sufficient vegetation (e.g^ grasslands) to support a
variety of wildlife. This partially forested ecosystem was selected because: (1) this description applies
broadly to many areas throughout the contiguous Uru^ States, (2) a variety of wildlife species are
Eiaied with partially forested areas, and (3) it was consistent with the waste management exposure
scenarios modeled for mis analysis. Itismportanttoreccfiuzethat,
may be broadly applied in a variety of exposure scenario^ they have a tow level of resolution with
respect to specific ecosystem types.
13, Categories of Ecological Recepton
Populations or communities likely to receive significant exposures to cadmium were identified for
die generic terrestrial and a generic freshwater ecosystem. Within each generic ecosystem, receptors
were identified based on: (1) the availability of data, (2) tfw spatial relate
forenvinmmentalcoritanunanrj,(3.)thebeh«vtorofrxrtertti^
"representativeness" of the receptor whfa respect to various trophic levels. The categories for ecological
receptors included mammals, birds, plants, soil community, fish, aquatic invertebrates, aquatic plants,
and benthos.
23 Rtceptor Identification art tte&aerteTrophk System
Although the identification of receptors is more easily accomplished on an ecosystem-specific basis
(e.g, deep water lake, grassland), receptors may be selected to represemtte major trophic elements of
generic aquatic and terrestrial food webs. For example, McVey (1994) presents a classification
developed by Schooner (1989) for the major trophic elements mtenesn^ food webs. Seven categories
were distinguished based on body size and dietary prefen
E-139
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Primary producers (i.e., plants)
Small leaf> or grass-eating herbivores (e.g^ numerous arthropods)
Larger herbivores (e.g^ deer, rabbits, voles)
Small carnivores (e.g* spiders and other predatory insects)
Medium-sized carnivores (e.g>, kestrel)
Larger carnivores (e.g^ fox, wildcats)
Medium-size omnrvores (e.g^ raccoons).
The categories provide a iiseftUMerarchy of tro^^
However, as &*oener (1989) poim* ou^ more specifwgroqjn^
included. In addition, the groupings ignore a critical fimctional component of teirestrial ecosystems:
organisms mat break d^fwn organic materials (Len decomposers). More important, the relationship
between these categories and me movement of chemicals man ecosystem (Le., exposure) is not
explicitly addressed.
A similar approach to identifying ecological receptors in the generic ecosystem is to select receptors
to represent each trophic level in a food chain or food web. In this way, the movement of the chemical is
accounted for, starting with the contaminated media, moving into producers (L&, plants) and lower
trophic level consumers (e.g^ invertebrates), and ultimately accumulating in the top predators. This
approach is appropriate for cadmium or other chemicals that btoaccumiilatem the food web bot may not
adequately address exposures to organisms mat IrvemmtmiateMm^actwim a (xatammated medium. In
addition; it is often difficult to categorize wildlife into a single trophic level Many species of wildlife
that ate considered carnivores consume some fraction of plant matter routinely in the diet. The diet of
terrestrial omnivores varies greatly depending upon me season, physiologk state of the animal (e.g^,
whetpingX and availability of certampiey hems. In short, the trophic level concept is a somewhat
artificial construct developed by "trophic ecologists" to bemv understand complex food web mteractions.
The nature of a food web (and ecosystem) varies over time and, to some extend the spatial distribution of
species and the time scale on which the food web is evaluated. Consequently, the trophic positions of
species within an ecosystem are in a state of flux.
Clearly, each of the above approaches has advantages. The hierarchical approach based on body sue
and diet provides important mfbmgtian an the erpmpmB pathways thrpiigh which CgflWI «frifM$ in*
likely to be exposed. The trophic level approach allows the movement of bioaccmnulatwe contaminants
like cadmium to be tracked through various levels in the food web so that exposures to top predators may
be assessed. Each of these approaches has the additional advantage of bemg amenable to an ecosystem
approach; receptors may be selected to represent categories or trophic levels within a given ecosystem.
The approach used to select ecological receptors for the hypometicd cadniium case study combines
both the category and trophic level approach described above and adds an additional component for
nrgimiMHg that urn entpnaed through enmttMit e-at^ft with • creifrfnttu^ mgrfi^im It IS essentially an
ecosystem approach in mat ecological receptors were selected based on their significance m the
ecosysten% their position along a contimium of trophic levels, and theg representativeness of likely
exposure pathways. However, it should be emphasized mat evaluating receptors wfthm the context of an
ecosystem does not guarantee that chemical s&essorswUl not cause adverse hnpacts at me ecosystem
level. Tha regpnnaa tn cxAmmm hy in
-------
2.3.1 Generit Freshwater Ecosystem
The generic trophic system for the limnetic zone consists of phytoplankton, zooplankton, small
fish (plankdvores), larger piscivorous fish, and piscivorous mammals and birds. The limnetic trophic
system was constructed as a linear food chain to simplify exposure estimates and to provide conservative
screening concentrations for wildlife. The generic trophic system for the littoral zone (sediment-based)
consists of phvtoplankton/detritus, zooplankton, benthic invertebrates, small forage fish, larger
piscivorous fish, and piscivorous mammals and birds. As with the limnetic zone, the littoral trophic
system was constructed as a linear food chain for cadmium to provide a simple framework for estimating
conservative screening concentrations. More complex food webs would not have been consistent with
the generic nature of the freshwater ecosystems.
Although some aquatic species are more representative of certain areas of the country than others
(e.g^ salmonids for coldwater lakes and streams), the national exit criteria must be protective of a variety
of-speoieB) ragnrdtec of their naonraphir lortrioa^Recognizing that only a small percentage of
freshwater species have toxicological data (Seegert et at, 1986), the range of freshwater species
identified by Stephen et aL (1985) for the development of national water quality criteria were included as
receptors. Aquatic plants also were considered as important ecological receptors. Both algae and
vascular plants are crucial to the proper functioning of aquatic ecosystems (e.g, oxygen production).
The mink and the river otter were selected as ecological receptors representing mammals in the
upper trophic levels of the freshwater ecosystem. These predatory mammals are found in a variety of
freshwater settings and may be exposed through the food chain crsurfira water as their primary drinking
water source. Although they represent a small range in body .size and are members of the same
taxonomic family, they rely heavily on fish as a source of nutrition and, therefore, will be highly exposed
through the food chain.
The representative species of birds are found in a variety of freshwater habitats and include a range
of body sizes across four taxonomic families. Species were selected mat rely heavily on fish or aquatic
invertebrates as a primary source of nutrition and will be highly exposed via ingestion of contaminated
prey. The eagle, great blue herozi,c4prey, and kmgfisber are examples of avias species that may depend
almost exclusively on fish. The mallard dock and the lesser scaup primarily consume invertebrates and
account for lower trophic level consumers G-e^~ trophic level 3). The spotted sandpiper was included
because ft feeds primarily on sediment dwellers and ingests a high percentage of sediment in its diet
The sandpiper diet represents a "high end* exposure to sediment relative to other aquatic fowl (Beyer,
1994).
The sed^ent community was considered a key functional component of the generic littoral
ecosystem. The species considered for the AWQC were used to represent the sediment community
based on the assumption that benflucspecies have a toxicological sensitivity to chemicals mat is similar
to mat of water-based specks (Di Tore et aL, 1991).
2.3.2 Generic Terrestrial Ecosystem
The generic trophic system for the terrestrial ecosystem consists of vascular plants* soil fauna, and
birds and mammals representing multiple trophic levels. Because cadmium tends to accumulate
differently in the terrestrial food web man in aquatic food webs (t.e., not linear), the generic terrestrial
E-141
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trophic system was designed as a food web with different dietary assumptions for each receptor (e.g^
percent ingestion of plants, invertebrates, etc.).
The lowest, trophic level is represented by species that feed primarily on vegetation (Le., herbivores
«T niminmft) *"** mdnAed thru* mmtm*lixn apaefca— the maaAmr vole, the enMntifnil rnhhit fln^ fhf>
whitetail deer— and one avian species, the bobwhite quail. These species are typical of most terrestrial
ecosystems. A second trophic level is represented by species that feed primarily on insects and soil
fauna and included one species of mammal, me short-tailed shrew, and one avian species, the American
woodcock. These species represent different dietary habits and, therefore, account for somewhat
different exposure pathways relative to me movement of different chemicals in soil biota. Three wildlife
species were selected to represent opportunistic feeders mat would be considered to be in the middle
trophic levels The deer mouse and the raccoon were selected to represent mammals, and the American
robin was selected to represent birds. Top predators were represented by the red fox (mammals), and me
red-tailed hawk .and American kestrel (iA, sparrow hawk). The red fox and red-tailed hawk are found
•tiiranghfliif mart of the T Tnftrri States and consume large insects (e.g^ grasshoppers) and a range of
vertebrates from mice to. large prey such as pheasants and snakes. Adcfttonal receptors will be added as
additional data needed to characterized food mtake, dietary habits, etc^ become available.
The selection of representative soil species was guided by two key principles. First, the members of
a group of organisms should use a resource in * siniilar way, have similar diets, be found msnnilar
locations, behave in the >same manner, and receive similar exposures to ctemicdstrcssors(Le., guild
theory). Second, taxonomic groupings are a useful indication of species-sensitivity to toxic compounds
as demonstrated m numerous stud^ on fish (le^tcndcok>gicalsm^ Based on the concepts of
functional redundancy within the guild and toxkx^logk^smiilarh^whluntexa, eight types of soil
to represent tb^ eommmihy of «oil famm These included nematodes, soil mites,
arthropods, and molluscs.
Vascular, terrestrial plants were selected as ecological receptors for the generic terrestrial ecosystem.
Due to their importance to the ecosystem and the general lack of data on plant toxicity, any species of
plant was used to represent terresUial vegetation as long as appropriate concentration-response data were
available. Ideally, plant toxicity data should include studies on different genera of plants (e.g^
monoccls,dicots) for adverse effects to plant populations. However, tenacity data were seldom available
for more than a few plant species. As a resuh,iepresentative species were defined very broadly for the
terrestrial plants.
2A StraoorChflraeteritmtaM
• There is no evidence that cadmium, a relatively rare heavy metal, is biologically essential
or beneficial; on the contrary, cadmium is a known teratogen and carcinogen, a pcobablemutagen, and
has been nnplicated as the cause of severe deleterious effects on fish and wMlife (Hoffman, 1995).
Freshwater biota appear to.be among the most sensitive receptonmtenns of cadmium toxicity. The
freshwater toxkrty of cadmiimi is givatry influenced D^
The toxic effects of cadmium are also greatry influenced by the fish life stage. Embryos and newly
hatched alevins are more resistant to cadmhun than are older alevins or juveniles. Cadmium toxicity to
fish has bera observed at concentratransm the range of (K7S to 7.7 ug/L Adverse effects to aquatk
mvettebrates are documented at relatively ktwcadnihim concentrations (0.15 to 3.0ug/l), both in the
laboratory and m die fieM (Hoffinanet «L, 19ft5X «nd me population growth rate of the algal species
E-142
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Asterionellajormosa was significantly reduced at 2.0 ug/1.
In general, cadmium is less toxic to aquatic organisms in hard water (i.e., high calcium carbonate
equilivents) than in soft water. Recently, the EPA has devoted considerable resources to delineating the
relationship between' water hardness and toxicfty to aquatic organisms (EPA, 1995): The Criterion
Continuous Concentration (CCC) for the protection of aquatic life revised as part of the Great Lakes
Water Quality Guidance accounts for differences in bioavailabilfty to aquatic life associated with water
hardness. For cadmium, the CCC for total, recoverable cadmium is calculated using the following
empirically-derived equation:
where In hardness is the natural teg of the water hardness in calcium carbonate equivalents (often
assumed to be SO mg/1). Based on the work of Stephen (1995), EPA recommended a conversion factor
f A f * frMtfmi""i to obtain a dissolved CCC (i.en CF x CCC** -
Numerous laboratory studies have documented the effects of cadmium toxicfty to mammals and
birds. The mam clinical signs of cadmium toxicfty m animals are anemia, retarded gonad development,
enlarged joints, scaly skin, liver and Idklney damage, and ratacedgrawta. Reproductive LOAELs for
laboratory rats ranged from 4 to 10 ppm, and an avian reprod*uctive IX3AEL of 19 mg/kg4 was reported
for mallard duck hens (Whfte and Fhiley, 1978). It is notewormy that ti» current upper limit of lOppb
of cadmium in drinking water for human health protection is not sufficient to protect many species of
freshwater biota against the biocidal properties of cadmium or against sublethal effects, such as reduced
growth and inhibited reproduction.
Aquatic biota - White btocaocentration of cadmium is apparent at all trophic levels, evidence
suggests mat only the lower trophic levels exhibftbiomagnification(Eisler, 1985). Tissue cadmium
concentrations for aquatic invertebrates have been positively correlated with aqueous cadmium levels
and inversely related to water calcium and IXX? concentration. In the freshwater food chain extending
from the alga Chlarella vu/gorir, to the cladocenn Daphrua magfia, to the teteost Leucospna delineates,
it was demonstrated that algae held 10 days in water containing 10 ppb of cadmium contained 30 ppm
dry weight, up from 4.5 ppm at the start (Ferard et at, 1983). Cladoceraas feeding on cadmium-loaded
algae for 20 days cotfamed 32 pfmWdty weight, up from 1^^ However, fish fed Cd»
com^minated cladocerans for 4 days showed no change in total body burdens. Whole-body BCF values
for cadmium uptake in fish ranged from 20 to 12,000. A whole-body BCF of S54 for total, recoverable
*TT fl""*"8?- *»«h «"•« f*tan*t*A fry
most values supplied from two studies by Knmada et al. (1973, 1980). For amphibians, Canton and
Stoof (1.982) observed a bioconcentration factor of \3QmXenopia laevis exposed for 50 days to a
solution of cadmium in water.
Terrestrial Mota - Studies on bioacaimiilation/bioconcentration in terrestrial vertebrates and
invertebrates have been identified and are currently being reviewed. Empirical data from sludge
application studies were used to derive the BCF for aboveground forage grasses and leafy vegetables.
The uptake-response slope for forage grasses was used as the BCF for plants m the terrestrial ecosystem
because many of me lepieseuiative plant-eating species feed on wild grasses. Below, Table 2 presents a
summary ofbiQccacentratkMArioaccmnulation factors developed for this analysis.
-------
Table 2
Summary of BioconcentratJOP/Bioamimiilatlon Factors
•cotoQlcml
fiah
twlMlfllri IMMJ •>
cropfuc WVM f.
• • !•• 1 t li 1 1
BMiwuiai
\wtabrataa
tM^***&>u-a*AA
MhraUWUfAU
-rth^nn.
trtanta
;«*.«F:,
BCF
BCF
BAF
BCF
BCF
BCF
m rafan to total luifaoa watar oonoi
:-:1'2S^P»
• •A nl« hn A i
wnofa-ooay
wtota-oooy -
.•aliata hnrfci
wnowvoay
whola-boaY
Mholabndy
whoan»ant
aSS,
300«
• -
'
• ^
M
0.14
gaomatrtc maan of 13 maaaurad
valuM forv»hol»-*xxjy BCFt aa
caao in nutttor now (a.g.,
KumadaataL. 1973)
data undar review
«»-W-
d-aund*^-
(fauiiatnc rnaan of nwawad
vakiaa from Daviaa. 1 983;
Haknka. 1979
U.S. EPA, 1992;
ntratfon
3.0 AMilysi* Phase
The analysis phase consists of the technical evaluation of data on die potential effects and exposure
of the stressor(s) identified during problem formulation (EPA, 1995). Inputs for the analysis phase have
been organized under (1) development of ecotoxicologkal benchmarks, (2) exposure data, including
exposure parameters for die ecological receptors as well as source information, and (3) a discussion of
the spatial and temporal distribution of cadmium with respect to the receptors of concern. The actual
risk estimates are described in Section 4.0 - Risk Characterization.
3.1 Development of EcotoxicoloficaJ Bemckxaarki
The ecotoxicologkal benchmarks reflect both the level of biological organization assessed (e.g^
individual, population, community) and the desire to ensure the viability of wildlife and die ecosystem in
which they live. As illustrated in Table 3, benchmarks were developed specific to the receptor and
exposure route of concern. For the suite of ecological receptors shown in Table 3, a no effects level (or
no effects concentration) approach was generally used to establish die benchmarks. However, for some
receptors, a no effects approach was considered overly conservative and a lowest effects approach was
used. For example, the highly diverse and nonstandard tenacity data on terrestrial plants make it difficult
to determine the ecological significance of various endpoints and effects levels (Fletcher et al., 1985).
Therefore, an approach similar to the Effects Range Low (ER-L) method developed by the National
Oceanographic and Atmospheric Administration was adopted (Long and Morgan, 1990). The ER-L is
the 1 Otfa percentile of the distribution of various toxk effects thresholds for organisms in sediments.
Tables 4,5, and 6 list the benchmarks for the ecological receptors in die generic freshwater and
terrestrial ecosystems. The following sections describe the rationale for selecting appropriate
toxico logical data and how benchmarks were calculated for ecological receptors in each of the generic
E-144
-------
Table 3. Ecological Receptors, Exposure Routes, and Media of Concern
Exposure media
Receptors
Mammals
Mink
Otter
Whitetaildeer
Eastern cottontail
Raccoon
Deer mouse
Meadow mole
Short-tailed shrew
Red fox
Birds
Bald eagle
Great.blue heron
Herring gull
Osprey
Belted kingfisher
Lesser scaup
Mallard
Spotted sandpiper
Red-tailed hawk
American kestrel
Bobwhlte quail
American woodcock
American robin
Other Receptors
Fish
Aquatic plants
Benthos
Daphnids
Soil organisms
Surface
water
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Contact
Contact
Contact
Aquatic
Sediment Fish Invertebrates
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion Ingestion
Ingestion Ingestion
Ingest) on
direct
Soil
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Direct contact
Terrestrial Terrestrial
Soil fauna plants vertebrates
Ingestion
Ingestion
Ingestion Ingestion Ingestion
Ingestion Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
Ingestiort Ingestion
Ingestion
Ingestion
Ingestion
Ingestion
-------
Table 4
Toxicological Benchmarks for Representative Mammals and Birds
witii Generic Freshwater Ecosystem
'Benchmark Vatw
0.82 («)
1.0
NQAB.
Sutou at aL, 1980
flwac otter
0.40 («)
1.0
NOAB.
SutouataL, 1980
1.4 (a)
nwlard duck
rap
1.9
NOAH.
WMtoataL, 1978
1.7 (a)
fnasano wMA
1.9
NCAEL
WMvataL. 1978
paatbkiaharan
1.6 (a)
malMdduck
rap
1.9
NOAEL
WMhtataL. 1978
mataid
1.
rap
NGAEL
VUMatataL. 1978
SOUp
2.1 (a)
"P
HOAEL
VWis»atat.. 1978
NGAB.
WM» at aL. 1978
herring jiui
1.8 (»)
rap
U
NOAEL
VMtoataL. 1978
3.2 (a)
NQAEL
WMaataL. 1978
TaMe5
Tozkok>fkaJ Beodunarla for Aqvatic IMt
ta Generic Freshwater Ecosystem
iiillilt
1
]'•••:'•• y.--.*- |x-;:£
Hah and aquatic
FCV
U.S. ERA. 1986
2.0E-03(l>
cv
Suav & Mataray.
1994
ER-L
nmunKy
1991
11
E-146
-------
Table 6
lexicological Benchmarks for Ecological Receptors
Associated with Generic Terrestrial Ecosystem
R*pf*s*ntirtiv*
-V.. ::. AMAd»iMM- '-•••• •'
:.::.; .:'. SPVCMS .:. . :"
dMrmouw
short-taaad
shrew
inaadow vote
EM&mi
COtlCNrial
red toe
raccoon
whtta-feJtod
deer
red-taled hawk
American
kaatrel
§.!.. rti« •«!
NBVweVfn
|t
2.3 (a)
1-9 (a)
0.78 (a)
0.56 (a)
0.53 (a)
0.27 (a)
1.9 (a)
3-4 (a)
3.t(a)
3.7 {a)
3-1 («)
3
-------
ecosystems. The benchmarks are categorized as adequate, provisional, or interim depending upon the
study quality and the sufficiency of the entire toxicological dataset with respect to «ndpoints of concern.
Generally speaking, these categories reflect die level of confidence in the benchmark (see RH, 1995 for
a detailed description of these categories).
3,1.1 Benchnuvks for Receptc^ in the Generic Freshwater Ecosystem
Afammals; Numerous studies were identified on the effects of cadmium toxichy to mammalian
species. These included a study by Loeser and Lorke (1977), which inferred a NOEL of 0.6 mg/kg-day
for dog exposure to cadmium; a study by Sordl and Graziano (1990X which calculated a NOAEL of 0.66
mg/kg-day and a LOAEL of 6.6 mg/kg-day far developmental effects in female rats; and a stody by
Sutouet aL (1980), which suggested a NOAEL of 1.6 mg/kg-day and a LOAEL of 10 mg/kg-day for
developmental effects in rats.
Although Sutou et al (1980) and Sorell and Grazuaic41S9^jepoited^imilacJ
NOAEL of 1.0 mg/kg-d from the Sutou et aL (1980) study was chosen to derive the mammalian
toxicological benchmarks because it contained sin^cientd^se^esponsemfbnnation and focused on
developmental endpbints at a critical lifestage. mtenns of population sustamabiliry, the decreased fetal
body weight observed by Sorell and Graziano et aL (1990) was not as significant as the decreased
embryonic implantations and live fetuses reported by Sutou et at (1980).
The study value from the Sutou et aL (1980) was scaled for species representatrve of a freshwater
ystem using a cross-species scaling algorithm adapted from OpreskoetaL (1994)
Benchmark -NOAEL
where NOAEL, is the NOAEL (or LOAEL/IO) forme test species, BWW is the body weight of the
wildlife species, and BW, is the body weight of the test species. This is the default methodology EPA
proposed for carcinogenichy assessments and reportable o^ianliry documents for adjustmg animal data to
an equivalent human dose (57 FR 241S2). Since me Sotou et aL (1980) study documented
developmental effects from cadmium exposure to matnig mate and femrie rats, the mean body weight for
bom genders for each representative species was used in the scaling algorithm to obtain the toxicological
Data were available on the reproductive, developmental and growm effects of cadmium. In
addition, the data set contained studies which were conducted over chrom^ and subchronk durations and
during sensitive life stages. The data set does not support an uncertainty factor to account for inter-
species difierences m toxicotogicd sensinvhy. The study value selected from the Sotou etaL( 1980) was
a NOAEL based on a developmental endpointthat was within an order of magnitude .of the lowest
identified NEL or LEL. Based on the data set for cadmium, the benchniaiics developed from the Sotou et
al. (1980) study were categorized as adeqaate (a).
Birds: Three studies were identified that investigated cadmium toxichy m avian species. The
effects on avoidance response to fright stimuli were assessed in one-week-old black ducks fed 4 or 40
13
E-148
-------
ppm cadmium (Heinz et aL, 1983). No information on daily food consumption rates were provided
therefore, the use of an allometric equation was required to convert the doses from dietary ppm to mg/kg-
day:
Food consumption - 0.0582CW"*1) where W is body weight in kg (Nagy, 1987).
Assuming a body weight of 0.053 kg, doses for this study were calculated as 0.1 and 1 mg/kg-
day. Ducklings fed 0.1 mg/kg-day ran longer distances away from a fright stnnulus than me controi
group or the 1 mg/kg-day ppm group. The authors could not explain why effects were, seen at the lower
dose level and not at 1 mg/kg-day.
Richardson et al. (1974) investigated the effects of cadmium on Japanese quail given an oral dose
of approximately 75 mg/kg-diet from hatching until 4 or 6 weeks of age. Since dairy food consumption
was not provided, the allometric equation presented above was used to convert the cadmium dose to
mg/kg-day. Using a body weight of 0.08 kg, the dietary dose was estimated at 10.5 mg/kg-day. After 4
weeks of exposure, quail exhibited signs of testicular hypoplasia, growth retardation and severe anemia
and after 6 weeks of exposure, both heart ventricles were hypertrophied. In another study, dietary
cadmium was given to mallard duck hens at 0.19, K9,and 19 mg/kg-day for up to °0 days (White &
Finky, 1978). No effects in egg laying were seen at the lower dose levels, however, egg production was
suppressed in the group given 19 mg/kg-day. Based on these results a LQAEL of 19 mg/kg-day and a
NOAEL of 1.9 mg/kg-day can be inferred for reproductive effects.
All of these investigations indicate effects mat could impair the survival of a wildlife- population.
However, the study by Richardson et aL (1974) was not considered suitable for derivation of a
benchmark value because of msufficient dose response information. Since behavioral effects were
observed at the lower dose and not at the higher dose, the Heinz et aL (1983) study also did not establish
a clear dose response relationship. Tberefore, the White and Fintey (1978) NOAEL of 1.9 mg/kg-day
was chosen for estimation of an avian benchmark value. The principles for allometric scaling were
assumed to apply to birds, although specific studies supporting allometric scaling for avian species were
not identified. Thus, for the avian species representative of a freshwater ecosystem, the NOAEL of 2.0
mg/kg-day from the White and Fintey (1978) study was scaled using the cross-species scaling method of
Opreskoetal.(1994).
Data were available on the reproductive and developmental effects of cadmium, as well as on
behavioral effects potential^ effecting survival Laboratory experiments of similar types were not
conducted on a range of avian species and as such, inter-species differences among wildlife species were
not identifiable. There were no other values in the data set which were lower man the benchmark value.
Based on the avian data set for cadmium, the beflchmarks developed from the White and Finley (1978)
study were categorized as adequate.
Fish mdAqjaifa fifrTTfffftfHftir: The Final Chronic Value (FCV) for cadmium of 1.1B-3 mg/1
was selected as the bendmiark protective of fish and aquatic invertebrates (U.S. EPA, 1986). The FCV
for cadmium is a function of water hardness and is catealated using the equation e(iai'*l*ll*1"*3JB^ (U^.
EPA, 1986), assuming a water hardness of 100 mg/L Since the benchmark is based on the FCV
developed for die AWQC and was within an order of magnitude of the lowest adverse effect levels for
daphnids, mis benchmark was categorized as adeqoate (a).
14
E-149
-------
rtgffgrffT pltni*r The toxicological benchmarks for aquatic plants were either (?) a no observed
effects concentration (NOEC) or a lowest observed effects concentration (LOEC) for vascular aquatic
plants (e.g., duckweed) or (2) ah effective concentration (£€„) for a species of freshwater algae,
frequently a species of green algae (e.g, Selenastnan capricornutum). Hie aquatic plant benchmark for
cadmium is 2E-03 mg/1 based on reduced population growth rate ofAsttrionettaformosa (Conway,
1977 as cited in Suter & Mabrey, 1994). As described in Section 4J.6, all benchmarks for aquatic plants
were ^'cn***** as interim (0-
The Supplemental Guidance to RAGS has derived sediment screening
values based on statistical interpretation of effects databases reported in publications from me State of
Florida (1994 as cited in EPA, 1995), the National Oceanic and Atmospheric Administration (1991), and
a joint publication by Long etaL (1995 as cited in EPA, 1995). The screening value for cadmium was
reported as 1 ppm based on the Contract Laboratory Program's (Of) practical quantification Urnit
(PQL). Another resource of sediment data is the National Oceanic and Atmospheric Administration
(NOAA), which annually collects and chemically analyzes sediment samples from shesJocatedJn
marine and estuarine environments throughout the United States as a part of the National Status
and Trends (NS&T) Program. -The chemical concentrations observed or predicted by the different
methods to be associated with biological effects are then sorted, and me lower 10 percentife and median
ntrations were identified. The lower 10 percentile in the data was identified as an Effects Range-
Low(ER-L) and the median was identified as an Effect Range-Median (ER-M). These two values are
not to be construed as NOAA standards, however they are used by the NS&T program to rank sites with
regard to the potential for adverse biological effects. The data suggest an ER»L of about 5 ppm and an
ER-Mof9ppm. Baaed on the large amount of cadmium sediment data, the degree of confidence in the
ER-L and ER-M values for cadmium should be considered as very high (Long and Nforgan,1991>
Although the sediment values discussed above have been developed from databases containing
information from studies conducted predominantly in marine environments, the authors indicated that
corresponding values being developed from a freshwater database are whfam a factor of three of me
marine based numbers. Because the sediment benchmark was not developed using EPA methods, it was
assigned to the category of interim (Q.
3.1.2 Benchmarks for Receptors m the Generic Terrestrial Ecosystem
Mammals: As mentioned previously in the freshwater ecosystem discussion, no suitable
subchnmic or chronic studies were found for mammalian wildlife exposure to cadmium. Because of the
luck of additional imtmiMiliin toxicity ftndtw, the'same surrogate-species study (Sutou et aL, 1980) was
used to derive the cadmium toadcological benchmark for maminalianspedes representing me tenvstrid
ecosystem. The study value from me Sutou et at (1980) study was scaled for species representative of a
terrestrial ecosystem using a cross-species scajmg algorithm Since
the Sutou etal. (1980) study documented reproductive effects from cadmium exposure to mating male
and female rats, the mean body weight for both genders for each representative species was used in the
scaling algorithm to obtain the toxicotogtcal benchmarks. Based on me data set for cadmium, the
benchmarks developed from the Sutou et aL (1980) study were categorized as adequate (a).
Birds- Additional avian toxicity dan were not identified for birds representing the terrestrial
ecosystem therefore, the Whins and Finky (1978) study on reproductive effects m mallards used in the
freshwater ecosystem, was also used to calculate a benchmark value. TheNOAEL of 1-3 mg/kg-day
from White and Finley (1978) was seated for species representative of a terrestrial ecosystem using a
15
E-150
-------
cross-species scaling algorithm adapted from Opresko et al. (1994). Based on the avian data set for
cadmium, the benchmarks developed from the White and Finley (1978) study were categorized as
adequate (a).
Plants: Adverse effects levels for terrestrial plants were identified for endpoints ranging from
percent yield to root length. As presented in Will and Suter (1994), phytotoxichy benchmarks were
selected by rank ordering the LOEG values and then approximating the 10* percentile. If there were 10
or fewer values fin- a chemical, the lowest LOEC was used. If there were more than 10 values, the 10*
percentile LOEC was used. Such LOECs applied to reductions in plant growth, yield reductions, or other
effects reasonably assumed to impair the ability of a plartpc^xilan'on to sustain h»lfisu
-------
Table?
Date Set Used to Derive Soil Fmona Benchmark for Cadmium
— ~
Amgntatitaftw
rW/TJUfUMUJ JMMUIVI
OR********
•LuntbricutntHiut
Ban*****
ftraMbaaMr
ntuxuptnM
ecosystem. As Table 8 suj
fish. The imDlications of t
HOEC
(mgfta)
10
O97
18.7
13J
13J
3^3
3J3
AOMe^M^*^
gmxh
PWrtWIWp
flRMttltap
grouping
fNfflaTtOO^S
toflmta.
btMCt
aimld
amtM
AflMKWMMwl
MUNUPUU
molusc
— —
HaigM«taL, 1982
«wStnaltn«laL, 1980
van 8baaton*«aL. 1989
vMCteMtMtetaL, 1990
Uatoeki Mai, 1962
van «toMMnt«(«l., 1990
RMMltfaL. 1981
inaMrtw It- w*« •••••iiijtH
-------
Table 8. Freshwater Ecosystem Exposure Factors for Mammals and Birds
Representative
Species
Mink
female
male
bom
River otter
female
mate
bom
Bald eagle
female
male
bom
Osprey
female
male
bom
Great blue heron
femaie
mole
bom
Maflard
female
male
bom
Lesser scaup
female
male
bom
Kingfisher
female
male
bom
Spotted sandpiper
g. , . — r^ ,.
/9HXW
mato
bom
•terringGuU
(tomato
mato
Body Weight
(kg)
0.70
1.34
1.02
- 7.32
8.67
7.99
4.50
3.00
3.75
1.77
1.43
1.63
2.20
2.56
2.34
U!
1.24
.1.16
0.73
0.86
0.75
0.15
0.15
0.15
0.05 .
0.04
0.04
0.98
1.21
1.09
•
f
f
Water Intake
tt/d)
0.05
0.13
- 0.081
0.60
0.69
0.65 .
0.16
0.11
0.14
0.09
0.08
0.08
0.10
0.12
0.11
0.06
0.07
0.07
0.05
0.05
0.05
0.02
OJD2 '•
0.02
0.01
0.01
0.01
0.06
0.07
0.06
e
e
e
e
Pood intake
(kg/d)
0.11
0:21
0.16
1.18
1.35
1.26 ;
•
0.54
0.36-
0.45
0.37
0.30
0.34
0.40
0.46
0.42
0.31
0.33
0.32
0.24.
0.26
' 0.24
0.07
0.07
0.07
0.03
0.03
0.03 .
0.19
0.24
0.21
a
a
a
c
c
d
d
c
c
b
b
b
b
b
b
c
c
b
b
b
Spring/Summer Diet
Consumption f% voL)
100% fish
(trophic level 3)
100% fish
(0.5 trophic level 3)
(0.5 trophic level 4)
100% fish
(trophic level 4)
100% fish
(trophic level 3)
100% fish
(trophic level 4)
100% aquatic invertebrates
(trophic level 2}
100% aquatic invertebrates
(trophic level 2)
100% fish
(trophic level 3)
100% aquatic invertebrates
(trophic level 2)
100% fish
(trophic level 3)
c >«porMd food miak* rot* wainot gendw «cc40e
d »i*mo» otpray food wo*» «• w« uwd to wHmatofeod Wofc» «w»
• • f«oort*a wow WOK» rot* woinot <
t m wporMd body w*gnr wot not om
E-153
-------
Table 9. Terrestrial Ecosystem Exposure Factors for Mammals and Birds
Representative
Species
.omiW«quoNanKaS77(bw)^X727
Spring/Summer Diet
Comumptten {% vol.)
snrew
female
male
13% plants
31% earthworms
39% invertebrates
Deer mouse
female
male
bath
44% plants
43% invertebrates
Meadow voie
female
mote
botti
98%ptanJ3
2% invertebrates
iGitem cottontail
female
male
bait)
100% plants
Jed fox
JLuBU^M
temOM
mole
both
4% plants
96% vertebrates
coccoon
female
mala
bofn
52%lnvertebrati
10% v«
Mhtte-toJed deer
female
mala
both
100% plants
tod-tailed hawk
100% vertebrates
American kestrel
49% invertebrates
51% vertebrates
male
bofr)
tortnem bobwnite
87% plants
13% invertebrates
male
both
American-robin
-------
for exposure are important to consider for two reasons. First, the modeling inputs for contaminant
release and dispersion must be considered with respect to the life span of the receptor of concern. For
example, the life cycle of a daphnid is on the order of days whereas environmental models frequently
average emissions over much longer periods of time. Although the average contaminant release may be
well below the ecotoxicological threshold over a period of months, the contaminant release over a period
of days or weeks may be sufficient to cause serious ecological impacts. Similarly, chronic effects in
birds and mammals may occur during relatively short periods of time in which higher man average
releases occur. However, because the analysis is based on advene effects mat occur during sensitive life
stages (e.g^ gestation, fry stage), the temporal scale of exposure - the length of time over which an
organism is exposed -may be less important than the timing of that exposure. Under the analysis,
release increments were modeled at 1 year, 3 years, and 9 yeats to determine the impact relative to
shorter-lived receptors. The environmental fate and transport models proved to be relatively insensitive
to this reduction in averaging time and, therefore, the standard release duration (e.g*, 30 years) was
applied to ecological receptors as well
4.0 Risk Characterization
4.1 Results
Hie risk estimates for ecological receptors were generated by comparing modeled cadmium
concentrations in soil, sediment, and surface water with the acceptable media concentrations developed
for the ecological receptors of concern. In essence, this approach is analogous to the hazsrd quotient
(HQ) approach used to evaluate noncancer risks in humans: HQ values above 1 indicate unacceptable
ecological risks and those below 1 indicate <& motinur risks to wildlife. The bask equations used to
calculate "safe" concentrations for wildlife are presented below.
For surface water, acceptable cadmium concentrations for birds and mammal.? were derived using the
formula:
btnchmark * bw
where
If * trrtalr* nf
benchmark ** lexicological benchmark (mg/kg-day)
bw » body weight (kg)
BCF » whole-body bioconcentration factor (L/kg assumed)
For receptors Jacking a bioconcentration factor for a particular prey tern (e.gn BCF not estimated for
aquatic invertebrates), mis formula includes surface water mgestion only. Consequently, the acceptable
surface water concentrations for the mallard, lesser scaup, and sandpiper do not reflect food chain
exposures. The benchmarks for the aquatic community and plants were used directly as acceptable
20
E-155
-------
For sediments, the benchmark shown in Table 5 was used directly'as die acceptable sediment
concentration for benthic dwellers. However, because the sandpiper ingests between 7 and 30 percent of
sediment in its diet (Beyer et aL, 1994), the previous equation was revised to account for sandpiper
exposure to contaminated sediments. Rounded to one significant figure, the central tendency value of 20
percent was selected to represent the fraction of sediment in the sandpiperdiet To calculate an
acceptable sediment concentration for the spotted sandpiper (C.J the following equation was used:
benchmark * bw
"*=
where
Cjrf » protective sediment concentration (mg/kg sediment)
1^ — a — dietary intake of sediment (021, in kg/d)
benchmark - toxicological benchmark (mg/kg-d)
bw » body weight for the spotted sandpiper (kg).
For soils, acceptable cadmium concentrations for terrestrial mammals and birds were estimated using
the approach developed by the U^. EPA (1990b, 199U) to evarote the ecological risks associated whh
dioxms. The underrymg principle bdiindtm^metb^
upper trophic levels is a function of (1) daily intake of food, (2) the dietary preferences of me receptors,
and (3) bioaccumulation (or biocooceuLnition for plants) of contammants fat food hems.
The algorithm used to calculate the protective exposure concentration (C^ for representative
species in the terrestrial food web is presented below, with food items laniied to four categories:
vertebrates, invertebrates, caulhwmiiia, and plants (AH 1993). The absorption (ABij) is generally
assumed to be equivalent between the test species' diet and wildlife diet an& therefore, the absorption
term does not impact-die calculations of protective concentrations.
_ benchmark x bwi
* ~* ~ I*I.(BAFJ x Ftj x ABIJ)
where
CMI - protective exposure concentration (mg/kg soil)
bwi - body weight for species i (kg)
li - total daily food intake of species i (kg/d)
BAFj « bioaccumulation factor in food item j (assumed unhless)
Fij - fraction of species Ps diet consisting of food Hem j (unhless)
ABij » absorption olf chemical in the got of species! from food ftemj.
For plants and soil fauna, the benchmarks shown in Table 6 above are used directly as the acceptable
soil concentrations- for those receptors.
21
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Table 10 shows the acceptable medium concentrations for the ecological receptors of concern. The
risk estimates for each receptor were calculated by dividing the acceptable cc«centration in to tne
modeled cadmium concentrations in soil (2.21E-Q5 mg/kg), sediment (3.69E-Q4 mg/kgX and surface
water (2.28E-06 mg/L). the comparison of values indicates that, even using conservative exposure
assumptions (e.g^ 100% of contaminated food orginates from site), the risks due to cadmium exposure
are very low. In all cases, the HQ is 2 or more orders of magnitude below 1.
4.2 Key Uncertainties and Issues of Concern
4.2.1 Problem Formulation Phase
Inference of Ecogvatem Protection - The uncertainty in assuming that protection of populations of
representative species and communities will protect the behavior and properties at the ecosystem level is
considerable. Indirect effects that may be important in an ecosystem, such as predator-prey
relationships, food webs, competition and otim-hHra-Kocyrttai interactions, are not directly measurable
from me eadpomts used in mis analysis. The mference that the ecosystem is protected from chemical
stresams by protecting key components that eon 0€ measured relies heavily on the assumption that the
correct components can be assessed. For example, tow concentrations of chemical stressors, while not
toxic, may elicit avoidance behavior from key species within an ecosytem. The avoidance may cause
significant changes hi the dynamics of predator-prey mteracboos, ultimately temKng to significant
changes in the properties of the ecosytem (e.g^ species abundance). Unfortunately, tools for ecosystem-
level modeling are currently inadequate to detenniiK protective concentrations for generic *^^
Despite the uncertainty in trying to confer protection to an ecosystem by pivtfo'^iijg some of hs parts, the
methodology developed in mis analysis wasxonsidered to be the most reasoiuujle approach available.
Generic Ecoaystema - Although me ecosystem approach is nfCfAttrv in order to select appropriate
receptors, it is clear that die generic ecosystems lack the resolution to identify key components in more
"realistic" ecosystems. For example, wetlands and nuuine/estuarine ecosystems were not selected
because the parameter distributions and algorithms have not been characteiized to model fate -and
tf&usport m these environments. This decision 'does not represent a value judgment on the importance of
marine/estuarine or wetlands ecosystems. Rather, it reflects the need to develop ecological exit criteria
using fate and transport models and data that are appropriate to generic freshwater and terrestrial
ecosystems. Wedands are acknowledged to be a Snosak of miportantecos>rstems" that pro
functions for natural and living resources and mediate btogeochemical tnnsfonnations of global
significance (Catallo, 1993). Indigenous species of wildlife mat are integral parts of the wetlands
ecosystems may iict be adeq^iater/tepieseate^ Moreover, habitat-
based endpoints take on additional significance in a wetlands ecosystem because global and regional
functions such as biogeocbemical gas exhanges (e.g^ C, O, N, H, and S) may be compromised by
chemical stressors.
^Ixiweit Effect The benehiMifa
effects concentrations (or levels) instead of lowest effects i concentrations (or levels). This level of
conservatism was considered appropriate for this type of case study. However, ft has been suggested that
a 20 percent reduction in a population is an appropriate measurement endpoint since h is the approximate
limit of detection for field measurement techniques on populations (Suter et aL, 1992b). It is unclear that
the detection limit for population effects is also biological significant; however, natural population
22
E-157
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Table 10
Acceptable Medium Concentrations for the Protection
of Ecological Receptors of Concern
NA
1-7E-Q2
NA
1.0&02
NA
NA
3J602
NA
Ospny
2.7&02
NA
NA
2.96401
NA
NA
226-02
NA
NA
7.66*00
2.56*01
NA
NA
NA
SE*00
NA
1.1E-03
NA
NA
2.0E43
NA
4.1E*02
NA
NA
5.8E+02
NA
NA
NA
NA
NA
NA
RtdfM
Z1EXB
NA
NA
1.16*02
NA
NA
&2E+OB
NA
NA
1JE*
-------
variability may exceed 20 percent for a wide variety of species. 1 Moreover, the presumption that
benchmarks must be protective of successive populations of organisms as well as the immediate threat to
reproducing individuals does not allow for recovery mechanisms or adaptation and may add to the
conservatism. Although models are available to assess population impacts from individual measurement
endpoints (e.g., DeAngelis et at, 1990), these models are limited in then- application and difficult to
receptors relied on a modified trophic element approach. As a result, representative species were not
selected based on their sensitivity to certain chemicals; they were selected primarily as a function of their
ecological significance and availability of data on their physical characteristics (ie., body weight, food
intake). Data deficiencies notwithstanding, use of a single species to represent other species with
different natural histories, ecological niches, etc., may not provide the most appropriate ecological
receptors for ecological risk assessment
4.2.2 Analysis phase
Receptor Selection - The selection of the suite of receptors was intended to confer a protection to
the entire ecosystem by representing key structural and functional components (e.g^ producers, grazer
guilds, predators). However, in establishing measurement endpoints for these assessment endpoints, a
number of uncertainties and issues of concern were identified concerning the development of
toxicological benchmarks. The approach used to select ecological receptors is based on the premise that;
if key components of the ecosystem are protected, then protection wiU be conferred to the ecosystem.
Although this approach is reasonable given the nature of the analysis (i.en generic) and the availability of
data, protection of measurable endpoints may not adequately protect all ecologically significant
rtors. For example, amphibians and reptiles have high ecological significance in certain food webs:
amphibians feed on insects and other invertebrates and are intergral to many aquatic food webs; snakes
keep rodent and insect populations in check and serve as prey for many of the representative species.
Thus, the selection of ecological receptors was ultimately driven by what could be assessed rather than
what should be assessed. It is not possible to determine whether the ecological benchmarks for cadmium
will be protective of amphibians and reptiles.
v«- Statistical Heigypnce - The use of no effects concentrations are questionable from a
statistical standpoint (Smith and Cairns, 1993). The NOECs and NOAELs are generated using
hypothesis-testing statistics and, therefore, the quantification of no effects levels depends critically on
the size and variability of an experiment; smaller and less precise experiments lead to higher values for
the no effects level (Hoekstra and Ewijk, 1993). LOECs and NOECs (and resultant MATCs) derived
using hypothesis testing have resulted in some chronic benchmarks for aquatic organisms being set at
concentrations causing greater than SO percent mortality (Stephan et aL, 1985). The selection of
measurement endpoints is inherently biased toward statistical relevance and not biological relevance. In
practice, NOECs and NOELs are used as no-effects levels even though the level of biological response
may be significant For example, the MATC (calculated as the geometric mean of the reported LOEC
and NOEC) has been shown to correspond to fairly high levels of effect Data from 176 tests on 93
1 Population variability is dependent on selecting an aputopriale temporal scale for the species in question. This
statement was intended as an illustrative example of issues regarding population variability.
24
E-159
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chemicals with 18 species indicated that average reductions in reproductive endpoints at the MATC were
20 percent for parental survival, 42 percent for fecundity, and 35 percent for an integrative weight/egg
parameter (Suter et al., 1987). Although the data requirements for alternative approaches such as the
benchmark-dose approach are considerable, additional research may be needed to provide benchmarks
that better represent biological significance.
Rdianee on "Population-Type" Effects - In recognizing mat population 4*** are not available, the
Science Advisory Board pointed outthat population impacts must be inferred from effect to individuals
(U.S. EPA, 19930. Consistent with SAB recommendations, endpoints were selected for which
population impacts could be reasonably demonstrated (e.g, fecundity, lethality). However, hi adopting
these "population-type" endpoints as toxicoiogical benchmarks, it was important to consider the entire
data set, including endpomts that may pose significant risks to indivknial organisms m the absence of
clear impacts at the population level In some cases, "nonpopulation" effects levels (e.g^ liver
pathology, immunological deficit) were not used to establish benchmarks because impacts at me
high chemical activity), exceeding a "nonpopulation11 effects level may result in toxic insult to a large
percentage of the population. For example, because the lifetmereproductw^
organism may be substantially less man the vatae of an oiganismthtf has reached tvproductiveniatunty
(SouM, 1987), adverse effects to a sufficient number of adah organisms may indirectly diminish the
reproductive fitness of the population (e.g^ through the mability to 'avoid predation). Ignotiug target
organ studies or effects levels mat may not be directly relevam to pcpdatkm impacts, particularly when
those effects levels are below reproductive effects levels, may result in critamtnat are ondeiptotective
of reproductiveiy mature organisms.
gpfrgqry Approach- Generally, the adequate category waa applied to a benchmark derived from a
no effect level and the data set provided information on a suite of endpoints (e.g^ life-cycle,
developmental, growth). The proviaiowU category was applied to a benchmark that was extrapolated
from a lowest effects level to a no effects leveL The interim category included benchmarks that were
derived with minimum data and associated wim high uncertainty. Although the category approach
provides a useful metric of uncertainty—* kind of romfbrt rate—the categories have nrt been vaUdated
quantitatively. Nevertheless, the categories acknowledge the uncertainties in the different methods and
data sets used to estimate toxicoiogical benchmarks. (Grven the substantial gaps m toxicoiogical data,
providing a qualitative uncertainty category may be the most appropriate way to address uncertainty
associated with ecological benchmark development)
T^hnrvtnrv tn Eldd F.i
ji - TTie toxicoiogical benchmarks for ecological receptors were
developed assuming that effects mat are observed in laboratory test species are applicable to wildlife
species under similar field conditions. As a resuh; there were ho laboratocy-to-field extrapolation factors
applied to account for the additional stress that may be encountered under field conditions (e.g^ cold or
drought). Van Straalen and Demenum (1989) and Stephan et aL (1985) examined arguments both for
and against a laboratory-to-field extrapolation factor and concluded that laboratory-to-field extrapolation
factors were not necessary; Le^ criteria derived wim laboratory data should protect soil fauna m me field.
However, other authors haw suggested that laboratory species tend to be orare homogeneous and have
narrower tolerance distributions man meg field counteiparts, and ttiat me distribution of the target
population of species is likely to have a different shape and scale relative tome laboratory species (Smith
and Cairns, 1993; Suter etaL, 1983; SeegertetaL, 1985). As a result, trw distribution of the radpoint
will be narrower for the laboratory species, m addition, Smith and Cains (1993) point out that local
25
E-160
-------
adaptation to conditions may make an individual species more or less tolerant to a chemical stressor.
The authors conclude by stating that the extent and variation between laboratory and field species have
not been investigated, although information on clonal variation to chemical stress in laboratory species is
available from Band et al. (1990).
Interspeciea Uncertainty - For mammals and birds, differences in interspecies uncertainty were
indirectly addressed through the use of the species-scaling equation. However, Opresko et al. (1994)
point out that the method has not been applied to wildlife by EPA and mat wildlife lexicologists
commonly scale dose to body weight without incorporating the exponential factor. In addition, scaling
may not account for physiolo^cal/biochemical differences in species sensitivity. Differences in
sensitivity that are contrary to estimates produced by the scalmg equation have been demonstrated for
several chemicals (e.g^ dioxin). However, the case-by-case approach relies on a heterogeneous data set
for cadmium that is unlikely to contain suffidert data to assert differences in sensitivity.
were limited to growth and yield parameters. This is consistent with the Registration Data Requirements
under the Federal Insecticide, Fungicide, and. Rodenticide Act (FLFRA), such as seed germination,
seedling .emergence, and vegetative vigor. However, the LOEC values in the Oak Ridge database (Will
add Suter, 1994)are the highest applied concentration of the chemical stressor, which elicited <£0
percent reduction in a measured response, ft is not clear whether mis level of response or other
resoonses reported mPHYTXDTOX are biologically signified In addition,
other effects such as RNA synthesis or CO, uptake may be more sensitive indicators of potentially
significant risks to plants. Clearly, further research is needed to define: (1) the most sensitive,
biologically significant endpbint for plants (e.g, seed germmation, early growth), and (2) the effects
level at which the effect should be considered significant in terms of plant population growth and
survival.
Sofl Ch«r«eterirtieg and Toriritv - Soil characteristics men as pR elav type and content, imn
oxide content, and organic carbon affect the ability of chemicals to be taken up by plants. As a result,
phytoxichyispartuuJydetenninedbysoUchancteristics. Cadmium bioavaUability is strongly
influenced by the iron and, therefore, cadmium phytotoxichy is expected to be lower in soils rich in iron
oxide (Alloway and Jackson, 1991). Differences in sofl characteristics create uncertainty in the
phytotoxfc benchmarks, possibly by an order of magnitude or more, since f» varies over an order of
magnitude (Carsel et ai, 19SS).
As is the. case with plants, various physkochemkal soil characteristics such as pH, organic matter,
and clay content affect tfaetoxicity of a constituent on soil organisms. As a result, me toxicfty of a
constituent is partuufy determined by the characteristics of the sofl in which the exposure takes place.
For example, the tenacity of copper to- the earthworm 6blotoiiaie»mbUghrycofnlatedwimthe
organic matter content of the soil (Jlggy and Streft, 1982). From data on bioaccumulation in
earth worms, it can be concluded that the bioavailability of metal may depend on pH, organic matter
content, cation exchange capacity, and clay content (van Gestel and van Straalen, 1994). However, the
quantification of each factor to the toxkity and bioavailabilhyof metals is almost impossible.
26
E-161
-------
Soil (Tommnnitv Approach - Although soil invertebrates may be classified according to ecological
function (e.g^ trophic level, feeding habits), few studies were identified that supported the assumption
that taxonomicdly related soil invertebrates have toxicologicaUy similar responses to chemical stressors
(e.g^ Neuhauser et at, 1986). In addition, many species of soil invertebrates were excluded that occur
only in specialized micro environments such as dung piles, carrion, and rotting wood (Le., niche
organisms). As a result, species were selected to represent a range of trophic levels and functions in the
community (rather than selecting the "most sensitive" species). This community-based approach
assumes that if key components in the soil community are protected, that community structure and
function will not be adversely affected. However, this approach has not been validated in field or
mesocosm studies, and mere are more than 100,000 species of invertebrates (excluding protozoa) per
square decimeter in forest, meadow, and arable soils (Eijsacken, 1994).
ToTldty to Soil Fanna - The RTVM methodology makes two ««onnptif>fiq yggarfj
distnT>utions underlying the toxicity date. The first is the distrfaitianwhlim individual species
responding to varying concentrations of a ffMf fain* Thin fa th^ r»gprm«* nf 'mAnriAn»\ cjwW a« a
measure of the parametric response of all the members of mat species. The second is the distribution
across species, i.e^ within a taxonomic group. This is the response of different species as a measure of
the parametric response of all the members of a given genera, class, family, etc. In general, the type of
distribution (U« normal, logistic, triangular) of the toxkfty data across species cannot be verified well
with the small sample sizes typically used mtaxichy testing. Stooff (1992) requires* test (Empirical
Distribution Function Test) as part of the RIVM methodology to detennh» if me toxieiry data fit a
logistic distribution assumption, but concedes that the power of the test is weak and mat only major
deviations from the logistic distribution can be detected. However, as shown by Soum and Cairns (1993)
the extrapolation constants used for calculating an HCp are Mt substantially dififerent when using a
logistic or normal model. Given all of Ibis however, it is unlikely that the actual function used to
describe the distribution is critical, relative to the uncertamty introduced by other assumptions (Smith
and Cairns, 1993). Furthermore, Romijn et al (1993) suggest using the data regardless of their
distribution so long as at least eight data points are available.
Erpoanrc Parameters tor tba Fresh nater ]E|go»VKtem - The exposure scenario assumes If*** the diet
for all receptors consists either offish or invertebrates. This assumption, although conservative, is
highly plausible; However, the eagle iai known to consume other larger prey (e.g^ herring gull) and may
not be adequately represented as a fifth trophic level consumer of large fish. However, both the mallard
and lesser scaup-consume a variety of insects and, depending on me season, approximately one-third of
the mallard diet may consist of aquatic vegetation! Unfortunatety, hiocfHVCCTitnrrinn 4f** cadini'T" in
aquatic invertebrates has not been thotoughry researched aid is, apparently, sparse. Assuming mat the
receptur diets consist entirely of fish or aquatic invertebrates probably results in a "high-end" exposure.
for these ecological receptors, although the distribution catinot be quantified whlM)utbk>accumulation
data on insects and bioconcentration data on aquatic plants.
TerteatrffJ TtncfoFy Stoa.- Some receptors' (c.g^ hawks, kestrels, and foxes) have hunting ranges
that are significantly larger man the contaminated areas assumed for waste management units (RTI,
1995). For example, a 200-hectare land application unit represents a central tendency value for field size
(RTI, 1995) and the home range of a red-tailed hawk can vary from a few hundred hectares to over IS
hundred hectares. Nevertheless, ft was determined, that 100 percent of the diet would be assumed to
originate from contaminated sources based 'on behavioral patterns of the representative species and the
nature of the toxicological benchmarks. The behavior patterns of many representative species suggests
27
E-162
-------
that it is reasonable to assume trm^ during breeding seasons, these species would stay close to the den or
nest to care for their young (Chapman and Feldhamer, 1982; U.S. EPA, 1993t). Consequently, the
effective hunting range during sensitive life stages may be significantly reduced, assuming that prey
availability does not drop due to other stressors. In addition, the lexicological benchmarks were often
derived from subchrbnic reproductive studies in which the study animals were administered the chemical
during a sensitive life stage (e.g., days 7 to 12 of gestation). The use of reproductive benchmarks from
studies of subchronic duration tends to narrow the .temporal window fbc exposure and, as a result, the
relevance of the total hunting range to exposure becomes less important For example, areas with high
prey density that are also within me area of contamination may provide substantial exposures in the short
(and possibly longer) term. If these exposures occur during sensitive life stages, the lexicological
benchmark may be exceeded. AJthcmgh assuming that 100 percent of the diet comes from a
contaminated area is conservative, it was considered a reasonable approach to protecting animals at
sensitive life stages (e.g., developmental stages).
Terrestrial Dietary Fractions - Hie dietary fractions identified in the Wildlife Exposure Factors
Handbook (U.S. EPA, 1993g) encompassed a broad range of dietary preferences for most receptors.
Major sources of variability include geographical region, season, test species, and analytical methods
(e.g^ mass of various prey vs. incidence of prey in the got). Although spring and summer diets were
selected to be consistent with sensitive life stages such as breeding and whelping, the variability adds
significant uncertainty to the terrestrial food web model In addition, limited data were available on soil
and sediment ingestion in most wildlife species. As with dietary preferences, the data appear to be
highly variable, making ft difficult to characterize the distributions.
Terrestrial Food Item Categories - The terrestrial food web algorithm includes food hems in four
categories: earthworms, invertebrates (excluding eartnworiusX vertebrates, and plants. To evaluate food
web exposures, bioaccumulation (biocoocentration for plants) values are required for appropriate prey
hems. Considering the variability in pioacranBulation offish species, grouping various prey species
under very general categories (e!g^ vertebrates) greatly increases the uncertainty of the estimate. Even
assuming mat BCFs are available for seven! species of vertebrate or insect, selecting a geometric mean
may greatly underestimate exposure if the receptor's diet is skewed toward certain species. Although the
robust data set examined for TCDD provides more confidence ia the food hem categories, data on
cadmium are currently lacking. Alternative methods should be considered to address the disparity
between the data requirements and data availability for the terrestrial food web. For example, specific
food chains could be identified to represent a complete terrestrial food web.
28
E-163
-------
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DO NOT QUOTE OR CITE
CASE STUDY D
WAQUOIT BAY
WATERSHED
Ecological Risk Assessment
Regional Risk Characterization Case Study
Risk Characterization Colloquium
Series C-2
OSWER and EPA Regions
August 1 &2,1996
Dallas, Texas
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WAQUOIT BAY WATERSHED
Ecological Risk Assessment
Risk Characterization Colloquium
June, 1996
Risk Characterization Issues
Case Study (Planning and Problem Formulation)
Office of Water
Office of Research and Development
U.S. Environmental Protection Agency
Draft
Internal Review Document
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WAQUOIT BAY WATERSHED
Ecological Risk Assessment
Risk Characterization Colloquium
June, 1996
Risk Characterization Issues
Case Study (Planning and Problem Formulation)
Office of Water
Office of Research and Development
U.S. Environmental Protection Agency
Draft
Internal Review Document
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Waquoit Bay Watershed Ecological Risk Assessment
Risk Characterization Issues
The Waquoit Bay watershed ecological risk assessment was initiated through a proposal
by managers in the Waquoit Bay National Estuarine Research Reserve (WBNERR) and EPA
Region I who are concerned about the changing quality of the Bay. The proposal came as a result
of an USEPA solicitation to identify watersheds appropriate for the development of case study
examples of ecological risk assessment that would apply the principals of ecological risk
assessment as presented in the Framework for Ecological Risk Assessment (USEPA, 1992) to
watershed problems. The purpose was to expand the process of ecological risk assessment and
demonstrate its value for community-based efforts to protect ecological resources. Waquoit Bay
is one of five watershed case studies being conducted across the country for this project. The
project, co-sponsored by the Office of Water and Office of Research and Development, is
administered through a Technical Panel under the Risk Assessment Forum.
Background
As the Agency shifts emphasis from command and control toward voluntary compliance
and community-based environmental protection, communities will take increasing responsibility
for determining what ecological resources are at risk and how best to protect them through
management action. Because of this shift, watershed or other landscape level risk assessments are
often not driven by mandates. In watersheds, many federal, state and local authorities and the
public have interest in and varying responsibilities for regulating and protecting valued ecological
resources. In Waquoit Bay, fourteen organizations and the public became directly involved in
determining what the watershed management goal would be for the risk assessment. The goal is:
"Re-establish and maintain -water quality and habitat conditions in Waquoit Bay and
associated wetlands, freshwater rivers and ponds to (I) support diverse self-sustaining
commercial, recreational, and native fish and shellfish populations; and (2) reverse
ongoing degradation of'ecologicalresourcesin thewatershed"
Key management decisions-under consideration that are believed important for achieving this goal
include control of nutrients from septic systems, reduction of bacterial contamination in shellfish,
and containment of ground water contamination from a Superfund site. However, to achieve the
watershed goals, important decisions about other stressors may be required, including possible
risks of alternative management strategies.
Colloquium Issues.
The Waquoit Bay watershed case study includes the planning and problem formulation
stages of the ecological risk assessment. It does not include a formal analysis or risk
characterization chapter. However, the requirements of problem formulation are similar to the
requirements of risk characterization with the exception that hypotheses about stressor-response
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relationships are presented instead of characterization of risk based on data analysis. As such,
many of the same criteria can be used for evaluation. There are no a priori decision criteria in this
risk assessment. All stressor-response relationships will be developed to provide information to
risk managers for their consideration.
Key questions to address when considering the Waquoit Bay case study include:
• how responsive is the risk assessment to management concerns and how well were
management issues kept separate from the assessment of risk.
• how well were assessment endpoints defined, stressors identified and exposure pathways
described;
• how clearly are uncertainties articulated, and the level of confidence described for
hypotheses presented;
• how well was the overall picture of risk presented; and
• where, in an ecological risk assessment of this type, are the risk characterization principles
of consistency and comparability most applicable?
General Structure and Content
The case^tudy is descriptive. It provides a summary of activities conducted to complete
the work and explains the rationale for different aspects of the case study. This format is used so
that the ecological risk assessment can serve as a demonstration project The case study should
provide the basis for a Science Advisory Board review on the process while being easily
understood by a broad spectrum of readers.
The first section of the case study is planning. The planning step is particularly critical in
watershed risk assessment because it is here that the management goal is established and
interpreted for the risk assessment Without the goal, there would be no direction for the risk
assessment since statutes and regulations are not the driving force, nor will mandates direct all
management decisions needed in the watershed. This section describes the process the risk
assessment team used to interface with risk managers in the watershed and how the goal was
derived and interpreted.
The second section is the problem formulation. A summary of available information is
provided to give a foundation for the case study results. This summary includes a characterization
of the ecosystem at risk, a discussion of observed ecological effects, and the known and predicted
stressors and their sources. Based on this information and the established management goals and
objectives, assessment endpoints were, selected. Assessment endpoints are defined by an
ecological component (e.g., finfish or eelgrass) and their attributes (e.g., abundance) that best
represent the management goals. (Note: in human risk assessment, humans Would be the
ecological component, and the attribute may be reproduction, health or other characteristic that is
valued and most likely at risk). Based on the assessment endpoints, a watershed conceptual
model and submodels were generated that represent a series of risk hypotheses about the
relationships between different assessment endpoints and stressors believed to adversely affect
them.' Pathways presented in the conceptual models are described as hypotheses in the text. Only
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two of the assessment endpoints are expanded into submodels in this draft. The final section is
the analysis plan. Here, two analyses are presented. The first is a comparative risk process that
provides the rationale for focusing planned analyses on a limited number of variables. The second
describes one analysis that can be conducted using available data from estuaries across Cape Cod.
Findings and Uncertainty
The results of problem formulation are based on an interpretation of, and decisions about,
how information and data on the watershed ecosystem are to be used for the risk assessment.
Based on available information, "findings'1 are a function of the reasonableness of risk hypotheses
proposed for the risk assessment and "uncertainty" relates to the types of analyses proposed.
Natural variability is a significant consideration when selecting measures for assessment
endpoints. In this case study, high natural variability was used to eliminate scallops as an
assessment endpoint. Uncertainty is specifically addressed in the generation of hypotheses, the
selection of analyses, and the consideration of what is possible to conclude in risk
characterization. A description of data limitations and uncertainty is included.
One of the key elements of this risk assessment is the explicit recognition of multiple
diverse stressors. Considerations of multiple stressors adds, significantly to uncertainty but will
increase the "transparency" of results. Suggestions by reviewers on how to better represent
possible interactions of multiple stressors would be valuable to the rislc assessment team. .It would
also be valuable for reviewers to consider how effectively possible confounding .variables and
alternative interpretations of information were highlighted, the team identified key studies,
data gaps, available data, descriptions about what is known about mechanisms for response,
possible conflicting data, and multiple exposures: The assessment will contain both qualitative
and quantitative components.
Context and Comparison
The guidance for risk context and comparison relates to the qualitative characteristics of
the "hazard" (stressor) and possible "alternatives to this hazard." Risk characterization is to
include a discussion about how risks compare, particularly to other risks addressed by a
regulatory program or past EPA decisions. Context and comparison take on somewhat different
aspects in this and other watershed ecological risk assessments.
Watershed risk assessments must address impacts by multiple sources of multiple
stressors, both in how stressors compare to. one another and how they combine to change risk.
Context and comparison are both addressed in problem formulation and risk characterization as a
comparison between different sets of stressors and effects. Their evaluation is intended to help
risk managers identify and prioritize key stressors that are causing the most adverse effects on
valued ecological resources. The complexity of this task is significant, but is handled in this risk
assessment with conceptual model development and a comparative risk analysts as a first cut at
making priority decisions about analysis.
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Context can be important when considering alternative management actions. In Cape Cod
major decisions are being made about how to treat groundwater contaminated plumes emanating
from a Superfund site. The plumes are approaching Waquoit Bay and other bays including
Buzzard's Bay. In Buzzard's Bay the risk to ecosystem processes from groundwater extraction,
treatment and reinjection is being compared io the risk of contamination reaching the Bay.
Although this particular stressor is not evaluated in depth in this Waquoit draft, it is an important
aspect of future management efforts in the watershed.
Past EPA decisions have less bearing on this risk assessment since there may or may not
be appropriate comparisons with related EPA or state actions. In Waquoit, some of the key
stressors are under local jurisdiction (nitrogen loading from septic systems) while others are
subject to federal and state action (Superfund contamination as mentioned above). Each of these
issues must be addressed individually to determine context and comparability.
Finally, information on similar ecological effects in other systems like Waquoit Bay are
key to understanding what ecological responses are likely to occur or have consistently occurred
in these ecosystems when exposed to a complement of stressors. In this risk assessment, changes
in eelgrass relative to land development that may be occurring across Cape Cod provides a
context for evaluating the consistency of an effect in similar but unique systems.
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WAQUOn BAY WATERSHED
ECOLOGICAL RISK ASSESSMENT
CASESTUDY
PLANNING AND
PROBLEM FORMULATION
REVIEW DRAFT
10 May 1996
Office of Water
Office of Research and Development
United States Environmental Protection Agency
Washington, DC
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Contents
Tables v
Figures v
Introduction I
1. Planning the Risk Assessment 3
1.1 Establishing the Management Goal 3
1.1.1 The Management Goal 3
1.1.2 Interpreting the Management Goal for Risk Assessment 3
1.1.3 Process for Selecting the Management Goal 4
1.2 Management Decisions 5
1.3 Purpose, Scope, and Complexity of the Risk Assessment , 6
2. Waquoit Bay Problem Formulation 9
2.1 Assessment of Available Information 9
2.1.1 Characterization of the Ecosystem at Risk .., 9
2.1.2 Ecological Effects 11
2.L3 Sources and Stressors 12
2.2 Assessment Endpoint Selection 14
2.2*1 The Assessment Endpoints 14
2.2.2 Endpoint Description and Rationale 15
2.2.3 Overlap of Assessment Endpoints and Their Application
to the Risk Assessment 19
2.3 Conceptual: Model Development 19
23.1 Watershed Conceptual Model 22
2.3.2 Risk Hypothesis Development 28
2.4 AnalysisPlaii * 40
2.4.1 Comparative Risk Analysis 40
2.4.2 Development of a Regional Model of Eelgrass Response
to Nutrient Loading .43
2.4.3 Potential Future Analysis for Other Stressors 50
3. Literature Cited 55
Appendix A - List of Participants in the Waquoit Bay Watershed Case Study
Appendix B * Newspaper Advertisement and Article on Waquoit Bay Watershed Case Study
Appendix C * Results of the Waquoit Bay Public Meeting
Table C-l: Environmental values/concerns that should be protected in the
Waquoit Bay Watershed
Table C-2: Types of Stressors affecting the Waquoit Bay Watershed
Table C-3: Waquoit Bay Watershed Stressors and ecological effects
Appendix D • Risk Management Team Meeting Attendees
Appendix E - Assessment of Available Information
Appendix F - Land Use in the Waquoit Bay Watershed
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Tables
1. The Waquoit Bay watershed management goal, interpreted as 10 management
objectives that are implied by and needed to achieve the goal 4
2. Summary statement of goals and objectives of federal, state, and local organizations
with management jurisdiction in Waquoit Bay 6
3. Nitrogen loading to water table, chlorophyll concentrations, and mean biomass of
macrophytes in three selected subestuaries of Waquoit Bay 14
4. Relationship of assessement endpoints to management objectives 15
5. Hypothesized effects matrix; each ceil represents relative effect of a stressor
or endpoint 41
6. Stressor ranks under three scenarios 42
7. Relative duration of stressors 42
8. Interaction among stressors 43
Figures
1. Waquoit Bay watershed and subwatersheds 10
2. Waquoit Bay watershed conceptual model 20
3. Eelgrass conceptual submodel 24
4. Hnfish community conceptual submodel 26
5. Waquoit Bay stream conceptual model 29
6. Waquoit Bay pond conceptual model 31
7. Waquoit Bay estuary conceptual model 33
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WAQUOIT BAY WATERSHED
ECOLOGICAL RISK ASSESSMENT CASE STUDY
INTRODUCTION
Waquoit Bay is a small estuary on the south coast of Cape Cod, Massachusett, prized by
residents and visitors for its aesthetic beauty and recreational opportunities. Rich in diversity, the
watershed covers more than S3 square kilometers (about 21 square miles) of freshwater streams
and ponds, salt ponds and marshes, pine and oak forest, barrier beaches, and open esruahne
waters. It provides a home, spawning ground, and nursery for a diversity of plant and animal life
including piping plovers, least terns (endangered birds), the sandpiain gerardia (an endangered
plant), and alewife, winter flounder, blue crab, scallops and clams, and anadromous and
catadromous fish. But the bay is changing. Eelgrass that supports much life in the bay is being
replaced by thick mats of macroalgae. Fish kills are occurring and the scallops are gone. The
aquifer underlying the watershed, which provides die communities of Falmouth, Mashpee, and
Sandwich their sole source of drinking water, is contaminated by plumes from a Superfund site.
Land development is changing the landscape and contributing nutrients and contaminants to the
bay. Local communities are concerned for their health and the value the bay adds to their lives.
Worldwide,, other estuaries are experiencing similar water quality problems as a result of
increasing numbers of people moving to coastal areas (Submerged Aquatic Vegetation
Workgroup, 1995). The history of Waquoit Bay hi Falmouth and Mashpee illustrates this trend
and the struggle between traditional economic growth and conservation of natural resources.
Initially valued for hunting, farming, and fishing, Waquoit Bay now primarily provides aesthetic
and recreational opportunities (WBNERR, 1989), demands that have generated residential
development and business for local marine-dependent industries. Across Cape Cod more than
65,000 permits for single-family homes were authorized between 1970 and 1989, a major portion
of which were in Falmouth and Mashpee (Culliton et al., 1992).
The environmental problems Waquoit Bay faces include eutrophication, habitat loss, and
resource depletion (WBNERR, 1989). These changes led to the designation of Waquoit Bay as
an Area of Critical Environmental Concern (ACEQ in 1979 by the Commonwealth of
Massachusetts. In 1988, the federal government and State of Massachusetts formally established
the Waquoit Bay National Estuarine Research Reserve (WBNERR). The estuary is a study site
under the Land Margin Ecosystem Research (LMER) project funded by the National Science
Foundation (NSF), the U.S. Environmental' Protection Agency (EPA), and the National Oceanic
and Atmospheric Administration (NOAA).' This is a multidisciplinary project studying the effects
of changing land use patterns on ecosystem function. LMER scientists, water resource scientists
from the Cape Cod Commission for regional planning, and scientists from the Buzzard's Bay
National Estuary Program are evaluating nutrient loading calculations and management options
for Waquoit Bay. In April 1995. a new U.S. Fish and Wildlife Refuge was established that will
provide a contiguous arc of undeveloped land on the bay. In place also are management plans for
federally endangered and otherwise protected species such as piping plovers, least terns, and
roseate terns. In May of 1994, Waquoit Bay was declared a Federal No-Discharge Zone, offering
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some .protection against dumping of boat wastes. Increased recreational boating and a
proliferation of docks led to new regulations on dock construction in the ACEC management
plan. AJong with Waquoit Bay, the trout spawning reach of the Quashnet River has been
designated an ACEC and the river classified as Class B, to be used for protection and propagation
of fish, other aquatic life and wildlife and for primary and secondary-contact recreation (Baevsky,
1991).
EPA Region 1 formally nominated the Waquoit Bay watershed in 1993 for inclusion in an
EPA-sponsored project to develop watershed-level ecological risk assessment case studies.
Waquoit was selected as one of five watersheds because of interest by local, state, and federal
organizations in the watershed, the type of watershed (estuarine), the diversity of stressors (e.g.,
nutrients, sediments, obstructions, ground water contamination), willingness by the WBNERR
and EPA Region I to lead the risk assessment team, and a substantial existing database. Although
significant research has been completed in the watershed to date, the value added by conducting a
risk assessment in the Waquoit Bay watershed is based on (1) a focus on multiple stressors and
relative risk, (2) identification of significant data gaps and design of a research agenda that is more
balanced and broad-based, and (3) an interpretation of risk mat is useful for pending management
decisions.
This document describes the work done by an interdisciplinary and interagency team of
scientists and managers (see Appendix A) to develop the Waquoit Bay watershed ecological risk
assessment It is organized into two sections. .The first, on the management goal for the
watershed, presents the goal and the process used to establish it The second section is the
problem formulation for the risk assessment The analysis and risk characterization phases of the
risk assessment are under development
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1. PLANNING THE RISK ASSESSMENT
The Waquoit Bay watershed ecological risk assessment was based on a proposal by
manager in WBNERR and EPA Region I who were concerned about the changing quality of the
Bay. Based on this interest, a risk assessment team was assembled (Appendix A) and planning for
the risk assessment began in 1993.
The objectives of the. planning were to establish clear and agreed-upon goals for
watershed resources, to determine the purpose for the risk assessment within the context of those
goals, and to agree on the scope and complexity of the risk assessment (USEPA, 1996). One of
the principal challenges for meeting planning objectives for this risk assessment was to develop a
management goal for watershed resources that diverse members of the community could support
To meet the requirements of planning, the risk assessment team (the Team) worked with
watershed risk managers (the Managers) to develop and implement a process for ascertaining the
interests and goals of the public; local, state, and federal organizations; and other resource
managers in the watershed. Below is a description of the goal and an explanation of how it was
derived and interpreted. The scope, complexity, and focus of the assessment are also delineated.
1.1 ESTABLISHING THE MANAGEMENT GOAL
The management goal for Waquoit Bay was generated through discussions with risk
managers and risk assessors in the watershed, participation on the Team by local risk managers*
and dialogues with interested parties concerned about watershed resources.
1.1.1 The Management Goal
Reestablish and maintain water quality and habitat conditions in Waquoit Bay and
associated wetlands, freshwater rivers, and ponds to (I) support diverse, self-sustaining
commercial, recreational, and native fish and shellfish populations and (2) reverse ongoing
degradation of ecological resources in the watershed.
1.1.2 Interpreting the Management Goal for Risk A
The management goal is a qualitative statement that captures the essential interests
expressed by different management organizations and the public in the Waquoit Bay watershed
(see Section 1.13). In order for the management goal to support an ecological risk assessment,
the goal was evaluated by the Team and interpreted as 10 management objectives believed to be
required to achieve the goal (see-Table 1). These objectives were intended to state explicitly what
kinds of management results were implied hi the general goal statement' By performing this kind
of evaluation, the Team provided feedback to the managers on the ecological characteristics of
the goal, developed a systematic process for identifying assessment endpoints that could be
directly linked to the management goal, and provided a way to measure achievement of the goal
for risk managers.
Table 1 is partitioned into.three categories. The "Estuarine and Freshwater" category
includes three objectives that are common to both surface water types. Four objectives under the
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Table 1. The Waquoit Bay watershed management goal, interpreted as 10 management
objectives that are implied by and needed to achieve th- goai
. •'•• >tt
Affected Areai^
~&
Estuaiine and
Freshwater
Estuaiine
Freshwater
PJBatiS
^ita*rV£
1
2
3
4
5
6
7
8
9
10
BSft'J.-*^1" .^^^ "'"' '"•-•-'•••''**&&!&!&&
Reduce or eliminate hypoxic or anoxic events
Prevent toxic levels of contamination in water, sediments, and biota
Restore and maintain self-sustaining native fish populations and their
habitat
the bay
Reestablish a self-sustaining scallop population in the bay that can
support a viable sport fishery
Protect shellfish beds from bacterial contamination that results in closures
Reduce or eliminate nuisance tnacroalgal growth
Prevent eulruphicauoa of rivers and ponds
Maintain diversity of native btotic communities
Maintain diversity of water-dependent wildlife
"Estuarine" category and three objectives under the "Freshwater" category are unique to those
waters. The 10 objectives are stated as goals for specific aspects of exposure, stressors, and
valued ecological resources. Assessment endpoints were selected and justified based on these
objectives (see Section 2.3)
Although the goal was developed by the the Managers, the specific management
objectives were generated by the Team based on available information on watershed resources
(Appendix A). The objectives were then provided to managers for their consideration and
approval (see Section 1.1.3),
1.13 Process for Selecting the Management Goal
The management goal was developed through a multistep process initiated and completed
by the Team. Three principal approaches were used: a public meeting, evaluation of written goals
by organizations having jurisdiction over or interest in the ecological resources of the watershed,
and a meeting of members of these organizations to review and approve the management goal and
Team-derived objectives.
Public Meeting. EPA, in conjunction with WBNERR, held a public forum on September
21,1993. The forum was advertised and reported in local newspapers (Appendix B) to receive
input on what was valuable to the public about the Waquoit Bay watershed and what the public
believed were the principal stressors placing these values at risk; Each* participant was asked to
answer two questions: (1) What do you value hi the watershed? (2) What is placing those values
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at risk? Participants provided a substantial list of values and an array of chemical, physical, and
biological stressors (Appendix C), This feedback provided a basis for Team generation of a
working management goal, which was used to guide the collection and evaluation of available
information during the initial stages .of problem formulation.
Organizational Goals. The written goals established for Waquoit Bay by local, regional,
and national resource management organizations with jurisdiction in the watershed were collected
by the Team and summarized. Based on written documentation published by the organizations, or
as represented by statute, the Team generated short descriptors which are provided in Table 2.
These organizational goals were used to refine the risk assessment management goal and develop
the 10 management objectives.
Risk Management Team Consensus. To finalize the management goal, members of
concerned organizations (see Appendix D) were invited to a meeting sponsored by WBNERR in
Waquoit on February 24,1995. The working management goal, the summary of organizational
goals, and the interpretation of the goal as 10 management objectives was presented meeting
participants. The management goal and objectives for the risk assessment were approved as
modified by the organization representatives at the meeting. Participants in this meeting are
considered the risk management team for the risk assessment They will be principally responsible
for implementing management plans in Waquoit Bay.
L2 MANAGEMENT DECISIONS
the ongoing and easily, observed degradation occurring in Waquoit Bay is causing
managers in the watershed to look for better ways to manage valued resources. Key issues
requiring decisions include nutrient control, bacterial contamination in shellfish, and containment
of ground water contamination. To achieve the goals for the watershed, there might also be other
important considerations.
Nutrient inputs to the watershed are recognized as a serious problem. Managers are
considering the feasibility of installing denitrification technology and alternative sewage treatment
for homes and businesses along the bay and in the surrounding watershed. Treatment of sewage
is a critical issue that must be addressed on technical, financial, and ecological grounds. The risk
assessment is to address the impact of nitrogen in the watershed and predict the effectiveness of
nitrogen reduction in meeting-management goals. Bacterial contamination of shellfish beds is a
related concern for sewage management
Managers are evaluating alternative management options for protecting the watershed
from ground water contaminants now reaching the ponds and expected to reach the estuary within
10 years. A proposed extraction and treatment plan might result in more significant ecological
effects than will occur if exposure to the contaminants is allowed. Alternative options must be
considered.
Boating and clamming activities are increasing in the Bay and might require more stringent
controls. Location of boating traffic and clamming could be important to reestablishing important
aquatic communities. Better enforcement of speed limits and fishing activities might be necessary.
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Table 2. Summary statement of goals and objectives of federal, state, and local
organizations with management jurisdiction in Waquoit Bay.
. -VidraHlw.- . .-T-raVi— '•'
. fc --- •*-«' r_ C ***' • •
/%^_ -^*_=?:>- _ • •, O ^..
Qrr
Association for the Preservation of
Cape Cod
"Assist (other organizations]... to decrease nitrogen loading to Waquoit
Bay"
Atlantic States Marine Fisheries
Commission
Coordinates marine fisheries management in state waters
Cape Cod Commission
"Protect the region's resources .
and shellfish habitat"
. protect and improve ceastai water quality
Citizen Action Committee (formed of
representatives from other groups)
Reverse ongoing degradation and protect water quality and habitats of
Waquoit Bay '
Citizens for the Protection of Waquoit
Bay. ,
"Preservation of me environment (physical, aesthetic and otherwise) and the
natural resources of me Waquoit Bay area' ___ -
Massachusetts Coastal Zone
Management
Protection of natural and cultural resources in the coastal zone*
Massachusetts Department of .
Environmental Protection
Non-degradation of coastal waters (Waquoit Bay is class SA, or waters
with DO > 5 mg/L and where shellfish do not require depuration)
National Marine Fisheries Service
Implements Magnnson Act for marine fisheries management in federal
waters, and the Marine Mammal Protection Act (with USFWS)
NOAA National Estuarine Research
Reserve System'
"Establish and manage a national network of protected areas'.-. Mobilize
state and community resources to mutually define and achieve:
protection and management goals and objectives*
U. S. Amy Corps of Engineers
Regulation and maintenance of navigational channdiiin riven and harbors;
ovenight over coastal armoring; issue permit! for construction in waters and
wetlands (Section 404) '
U.S. EPA
Implementation of national envir
Act
laws, including the Clean W;
U. S~ Fish and Wildlife Service
Trnpignwmtarinn of die Endangered Species Act; management of National
Wildlife Refoges J- •'
Waquoit Bay National E
Research Reserve
"Protect in perpetuity for the purposes of research and education;.~
Promote stewardship and estuarine awareness through outreach activities..."
Waquoit Bay Watershed
"Evaluate possible options to improve water quality in the watershed"
Among the more critical considerations for many of these stressors is land development
and use. Recommendations concerning land use that are based on ecological risk are desired.
L3 PURPOSE, SCOPE, AND COMPLEXITY OF THE RISK ASSESSMENT
The purpose of this risk assessment was to determine what and how human activities are
contributing to ongoing degradation of valued ecological entities in the Waquoit Bay watershed.
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Specifically, it was designed to evaluate the relative contributions of dominant stressors to
support management decisions about changing land use, installing new sewage treatment
technology, evaluating management options for cleanup of groundwater contamination,
identifying key research needs, and providing the framework for predicting what effect possible
management actions will have on key ecological resources at risk. The risk assessment was not
legally mandated. The WBNERR is particularly interested in the risk assessment as a vehicle for
developing a research agenda. The risk assessment will also serve as a source of information as
several governmental organizations begin management of contaminated ground water.
The intended scope of the assessment was to address individual stressors' effects and the
combined risk of multiple stressors within the last 10 years in comparison with historical records
spanning SO years. Although significant data on the watershed have been collected, most are
related to nutrient inputs and "build-out" (i.e., residential and other land development), with
additional data on groundwater contamination. Relatively few data are available on the biological
changes that have occurred as a result of these stressors or other stressors identified by the Team.
although this is beginning to change, in part due to the development of problem formulation.
While the problem formulation is as broad as possible, the scope of the risk assessment was
narrowed to reflect data limitations. Where data are few, the Team identified key missing
information and made recommendations on types of data collection for future work to assess the
combined impacts of multiple stressors.
During problem formulation, the intent of the Team was to be as complete1 and
comprehensive as possible about relationships between stressors and ecological values selected as
assessment endpoints within the 21-square-mile area representing the surface watershed The
conceptual models developed include all identified sources of stress, stressor types, effects, and a
selection of assessment endpoints that best represent the management goal for the fresh and
estuanne waters of the watershed. The terrestrial component is not represented in the risk
assessment aside from one assessment endpoint on water-dependent wildlife habitat and
recognition that terrestrial impacts influence what occurs within water. Although the ground
water component underlies the watershed, it is not confined within the 21-square-mile area and
therefore represents a scale larger than that of this risk assessment
Once conceptual models were developed, it was the intent of the Team to select specific
stressor-assessment endpoint relationships to pursue, based on both the importance of the
relationship to perceived overall risk and the amount of data available to evaluate the relationship.
lii some cases assumptions were made to allow analysis, understanding that these assumptions
add to the uncertainty of results. The Team will attempt to evaluate the combined risk of multiple
stressors.
Limitations in the risk assessment reflect significant limitations on available resources. All
members of the risk assessment team are professionals from federal, state, and local organizations,
who provided their expertise and time without grant or contract funds. Limited contract support
was used to provide some assistance to the team. Although efforts were made to foster more
academic participation, this was directly limited by the Team's inability to provide funding. Key
researchers in the watershed were included as resource people. No new data were collected to
conduct this assessment, but best efforts were made to use available data.effectively. The success
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of this risk assessment was based on effective leveraging of available resources. Limitations,
although significant, did not prevent the achievement of important results
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2. WAQUOIT BAY PROBLEM FORMULATION
To develop problem formulation, a formal process was used to generate preliminary
hypotheses about why ecological effects in Waquoit Bay have occurred and to predict changes in
ecological responses both to continuing stressor inputs and to identified management actions that
might reduce stressor inputs. In the watershed, stressors of long duration were identified, as well
as potential risks from expected future human activities. To complete problem formulation, it was
necessary to evaluate historical records on the ecological characteristics of the bay and the
dominant human activities over comparable time periods, as well as to evaluate current status.
This information provided the basis for predicting ecological responses to management actions
and future stressors.
The Waquoit Bay problem formulation is based on an assessment of available information
that provided the foundation for risk hypothesis development A brief summary of key
information is provided below and supplemented by more detailed information in Appendix E,
Based on the management goal and available information, assessment endpoints were selected by
the Team. These assessment endpoints were used as the focus in the development of conceptual
models and the analysis plan. The following sections describe the result of these steps in the
problem formulation process.
2.1 ASSESSMENT OF AVAILABLE INFORMATION
The initial step in problem formulation was to identify and assess available information on
the characteristics of the watershed, observed ecological effects, and possible stressors on the
system. This section provides a brief overview of information on the Waquoit Bay watershed. It
highlights the information most pertinent to understanding the risk assessment and is not intended
to-be comprehensive. More comprehensive information is provided in Appendix E.
2.1.1 Characterization of the Ecosystem at Risk
The Waquoit Bay watershed covers more than S3 square kilometers (about 21 square
miles) and spans parts of the towns of Falmouth, Mashpee, and Sandwich on the south coast of
Cape Cod, Massachusetts (Babione, 1990; Cambareri et al., 1992,1993). It extends 8 kilometers
(5 miles) from the head of the bay to the regional ground water divide in Ac vicinity of Snake
Pond (Figure 1). The watershed includes esmarine and freshwater systems encompassed in seven
subwatersheds (Childs River, Sage Lot Pond, Quashnet River, Eel Pond, Head of the Bay,
Hamblin Pond, and Jehu Pond) and four large ponds (Ashumet, Johns, Snake, and Flat).
The Waquoit Bay watershed, like all of Cape Cod, is a geologically young landform
composed of glacial materials deposited on top of bedrock toward the end of the Wisconsinian
Glacial Stage about 12,000 years ago (LeBlanc et al., 1986; Qldale, 1992): The watershed lies
entirely within the Mashpee pitted outwash plain. The term pitted refers to sites where blocks of
glacial ice were buried during glacial retreat When the blocks melted, depressions formed and
filled with water, creating numerous kettle ponds (e.g., Ashumet and Johns ponds).
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Watershed
Map Area
Subwatersbeds:
1-Eel Pood
2-ChildsRiver
3 • Quashnet River
4-Head of the Bay
5 - Hamfalin Pond
6. Jehu Pood
7 -Sage Lot Pond
A - Ashumet Pond
B - John's Pond
C - Snake Pond
D-Flat Pond
Figure 1. Waquoit Bay watershed and sub watersheds (Barwiey and Sham, in prep.).
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Waquoit Bay may Have originated as a kettle pond whose southern margin was flooded by
subsequent sea level rise. The bay is a shallow estuary approximately 1.2 km (4,000 feet) wide
and 3.4 km (11,000 feet) long with an average depth of 0.9 m (3 ft). Tidal exchange to Vineyard
Sound occurs through two dredged-channels and a breach caused by Hurricane Bob in 1991.. The
action of winds, waves, and currents continually erodes and displaces the loose glacial sand and
gravel forming coastal sand dunes, sea cliffs, barrier beaches, and salt marshes.
The watershed's climate is maritime, with warmer winters and cooler summers Chan more
inland areas of New England, and annual precipitation between 107 and 112 cm (42 and 44 in).
Fifty percent of fresh water entering the Waquoit Bay estuary is from precipitation-23 percent
from direct precipitation and 27 percent from groundwater recharge (Cambareri et al., 1992).
Ground water recharge is approximately 45 percent of the total precipitation. The remaining 50
percent of fresh water entering Waquoit Bay comes from the Quashnet and Childs Rivers. The
porous, sandy glacial soils promote rapid percolation of rain, nutrients, and contaminants into the
subsoil and ground water.
Cold south-flowing Gulf of Maine waters and warm north-flowing Gulf Stream waters
mix off the coast of Cape Cod to form a biological transition zone between the Virginian
(temperate) and Acadian (boreal) biogeographic provinces (Ayvaziam et al., 1992), producing
more diverse biotic communities and habitats than occur in either province. The combination of
salt, estuarine, and freshwater systems within the watershed augment mis diversity. Critical
resources in the Waquoit Bay watershed include freshwater wetlands on the pond shores;
anadromous fish runs in the rivers; salt marshes, eelgrass beds, and barrier beaches in the estuary;
and upland woodlands (VanLuven, 1991). The surface water ecosystems support a variety of
food resources for aquatic, terrestrial, and avian wildlife and include commercially and
recreationally important fmfish and shellfish.
2JU2 Ecological Effects
Water resources in the Waquoit Bay watershed are .exhibiting signs of water quality
degradation. Waquoit Bay is becoming eutrophic, as evidenced by excessive algal growth that
decreases light penetration. Light-dependent eelgrass beds have almost disappeared from the bay.
Documented declines in the numbers of flounder, pollack, white hake, and other eelgrass-
dependent species parallel the loss of eelgrass. The bay scallop, an important commercial and
sport species, has virtually disappeared. When several consecutive cloudy days occur during
summer months, mass deaths of aquatic-organisms occur, presumably from respiring algae that
deplete dissolved oxygen. Increasing incidents of shellfish bed closure from bacterial
contamination are also a source of concern in the estuary.
Freshwater components of the watershed also are changed. Stream flow alterations have
resulted in a loss of reproductive habitat for traditional herring runs and migratory fish spawning
areas. Malformations and tumors in fish living in the kettle ponds may be indicative of exposure
to contaminants. Freshwater ponds are showing increasing levels of algal growth, which is likely
to alter the aquatic community. Targeted changes of concern include:
Blooms of phytoplankton and macroalgae.
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• Loss of eelgrass habitat and .issociated species, in particular, bay scallops.
* Changes in species composition and declining abundances of commercially important
finfish and shellfish.
• Mass mortalities of fishes and invertebrates in the upper bay and ponds.
• Reduced water flows in herring runs and trout streams.
2.1.3 Sources and Stressors
Multiple sources of stress were identified in the watershed. For each of these sources,
multiple stressors could also be identified^. More than one source may produce the same
complement of stresspr types, but the exposure pathway and specific characteristics of the
stressors may vary. The following highlights key sources and key stressor types with minimal
discussion of exposure pathways and characteristics. Refer to Appendix E and the section on
conceptual models (Section 2.3) for more information.
Sources. The main sources of stress identified in the Waquoit Bay watershed include
agriculture, atmospheric deposition, residential development, industrial uses, and marine activities.
Changing land and water use patterns along the coastal and upland areas in the Waquoit Bay
watershed are largely responsible for increasing stressors in the watershed (Appendix F). Some of
these affect local resources but occur outside the watershed, including armoring of the coast,
which shifts sediment deposition along barrier beaches; offshore fishing, which depletes stocks of
commercially valuable species; and wet and dry atmospheric deposition from motorized vehicles
and industries. Principal sources of stress in the watershed include the following:
• Cranberry cultivation which results in the use of fertilizers and animal wastes, the
application of pesticides and herbicides* and the construction of flow control structures
mat alter surface water flow.
• Atmospheric deposition from local and regional automobiles, lawn mowers; and motor
boats; on a larger spatial scale, nutrients (in the form of Nbx's) from industrial
emissions, and toxic chemicals, including mercury, mat originate outside the
watershed.
• Residential development, which contributes nutrients to the system through fertilizer
use on lawns, golf courses, and-gardens, and on-site septic systems; housing and road
construction, which results in habitat loss, sedimentation, and additional runoff of
nutrients, contaminants, and sediments from construction sites, and an increase in
impervious surfaces; and private and municipal well development, which .alters ground
water flow.
• Industrial discharges to groundwater from the Massachusetts Military Reservation
(MMR).-a Superfund site on the upper western portion of Cape Cod that is
contaminating ground water (a sole source aquifer for drinking water) with chlorinated
solvents and fuel constituents; sewage treatment facilities that results in phosphorus
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inputs to ponds; and increased runoff of nutrients, sediments, and contaminants from
impervious surfaces.
• Marine activities including construction and operation of marinas; and recreational
boating and dock and pier construction which disturbs sediments, alters habitats, and
contributes nutrients and contaminants; dredging and shoreline modification for
waterway maintenance, which disturbs sediments; sheilfishing which disrupts eelgrass
habitat, resuspends sediments, and adds harvest pressure; and recreational fishing in
the estuarine, river, and pond environments, which also adds harvest pressure.
Stressors. Seven principal stressors were identified-two chemical, three physical, and two
biological. Each stressor has more than one source contributing to stress in the watershed. Each
stressor was characterized on the basis of its type, its mode of action, and the general ecological
effects that might result from exposure to the stressor. In addition, information on the intensity.
frequency, duration, and spatial scale were reviewed for each stressor where available. Principal
stressors include:
• Nutrients, which are implicated as a major cause of nuisance macroalgal blooms and
eelgrass decline in the bay (Table 3) and increasing phytoplankton blooms in ponds in
part because of the porous,, sandy soils in the watershed, which promote rapid
percolation of nutrients from land deposition, septic systems, and other inputs into
ground water.
• Chemicals that may be toxic to organisms in the bay, streams, and ponds, primarily
mobilized chlorinated solvents and fuel constituents from MMR contaminant plumes,
open storm drainage ditches, and nonpoint sources such as road runoff, migration of
pesticides, on-site septic disposal system leachaie and atmospheric deposition of
mercury, lead, and organic contaminants.
• Suspended and resuspended sediments that increase turbidity and decrease light
penetration to eelgrass beds, and can weigh down eelgrass blades both directly and by
increasing epiphyte weight; and, as a result of loss in eelgrass, a shift in deposition.
• Physical alteration of estuarine habitat including increased sediment disturbance,
bottom disruption, and shading from dock construction; mechanical disruption from
clam digging, boat propellers, and moorings, and habitat fragmentation that results
from these activities.
• Altered flow or hydrologic modification where the flow volume, velocity, and path of
rivers results in loss of spawning habitat for anadromous fishes.
• Finfish harvest pressure, which directly affects fish mortality in offshore species from
commercial fishing activities, and recreational fish in freshwater rivers and ponds.
• Eelgrass wasting disease caused by the slime mold (Labyrinthula), which can act
synergistically with stress on eelgrass from reduced light conditions.
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Table 3. Nitrogen loading to water table, chlorophyll concentrations, and mean (±
standard deviation) biomass of macrophytes in three selected subestuaries of Waquoit Bay.
Childs River
14,209
25.5 ±7.6
335 ± 39.8
0
Quashnet River
14,534
5.9 ±1.7
150 ±14.3
Sage Lot Pond
331.5
3.9 ±1.2
90 ±12.1
117 ± 12.6
Adapted from Valiela et al. (1992).
2.2 ASSESSMENT ENDPOINT SELECTION
The Team's selection of assessment endpoints was based on societal values expressed in
the management goal and objectives^ well as an evaluation of available information to ensure
that the endpoints were ecologically relevant in the watershed and were susceptible to identified
stressors. The assessment endpoints are measurable attributes of valued resources that includes
both an entity-(e.g., eelgrass) and a measurable attribute (e.g. area! extent). They provide
direction for the assessment and are the basis for the development of questions, predictions,
models, and analyses. The Team's identification of an assessment endpoint does not imply that
data currently exist in Waquoit Bay to quantify attribute changes. Assessment endpoints are only
required to support the ability to collect data for quantification.
2.2.1 The Assessment Endpoints
Eight assessment endpoints were selected to represent estuarine and freshwater
components of the ecosystem and ecological and human health concerns. In some cases overlap
among assessment endpoints was recognized and endpoints were combined or eliminated later hi
the process. The assessment endpoints selected for the Waquoit Bay watershed ecological risk
assessment include:.
• Estoarine eelgrass abundance and distribution
• Resident and nursery estuarine finfish diversity and abundance
• Eelgrass-dependent estuarine benthic invertebrate community diversity and
abundance
• Trout and alewife migratory fish reproduction
• Riverine benthic invertebrate community structure and function
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• Freshwater pond trophic status
• Water-dependent wildlife feeding and nesting habitat
• Bacterial and contaminant content of fish and shellfish
2.2.2 Endpoint Description and Rationale
Assessment endpoints were seiected based on three criteria: how well they represent the
management goal (societal value), how well they represent ecological integrity in the ecosystem
(ecological relevance), and how likely they are to be exposed to and adversely affected by known
stressors (susceptibility). To judge societal value, each endpoint was evaluated relative to the 10
management objectives identified during planning (Table I, Section 1.1.2). Table 4 shows which
management objectives each endpoint addresses. Ecological relevance and susceptabiiity were
both evaluated based on available information on ecosystem structure and function and known
and predicted stressors. In the descriptions below on the assessment endpoints, the rationale for
selection based on these three selection criteria is provided.
Table 4. Relationship of assessment endpoints to management objectives.
9999999999999999999999!
eelgrass habitat
finfish diversity
bentnic invertebrate community
migratory fish reproduction • .
riverine bentnic invertebrate
community
freshwater pood trophic status
water-dependent wildlife feeding
& nesting habitat •
bacterial & contaminant content
of shellfish and fmfish
999=
X
X
9991
X
X
X
999
X
X
X
9999
X
X
X
9991
X
X
9991
•
X
9991
X
X
X
9991
X
991
X
X
•99
X
.
Considerable overlap and interdependence among objectives and potential endpoints are
recognized. For example, objective 5 (reestabiishment of scallops) would require achieving
objective 1 (elimination of hypoxia), objective 2 (prevent toxicity) to prevent scallop death, and
objective 4 (re-establishment of edgrass) to provide suitable habitat Objective 5 (juvenile scallop
habitat) would require achieving objective 7 (eliminate macroalgae) because local hypoxia is
caused by decaying algae at the bottom of the mats, and macroalgae shade and replace eelgrass.
This type of evaluation was used to identify multiple sources of stress and the variety of possible
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pathways for loss of an ecological value. The objective r "o identify the complement of necessary
and sufficient conditions for achieving management goa:
Each assessment endpoint is described below to highlight its characteristics as they relate
to ecological relevance, susceptability to known stressors, and societal value, with specific
reference to the management objectives.
12.2.1 Estuarine Eelgrass Habitat Abundance and Distribution
Eelgrass (Zostera marina) is a rooted vascular plant that grows subtidalry on mud to
gravel bottoms in zones of fast-moving or quiet waters where salinity ranges between 20 and 32
parts per thousand. Eelgrass roots and rhizomes decrease erosion and increase sedimentation.
Eelgrass blades promote deposition by interrupting water flow, and trapping suspended
sediments, thereby adding to the available food within the meadow (Short, 1984,1989).
Eelgrass habitat abundance and distribution was selected as an assessment endpoint
because eelgrass beds provide prime living, feeding, and nursery habitat for a large and significant
aquatic community including juvenile scallops, invertebrates, and forage fish that sustain larger
fish species (Heck, 1989; Thayer et al., 1989; management objectives 3 and 4). Eelgrass is
highly susceptible to water quality conditions and requires clear waters with ample light
penetration for photosynthesis. Shading by algae and .sediments directly, impacts eelgrass growth.
Excessive growth of macroalgal mats has displaced eelgrass in Waquoit Bay (objective 6).
Abundance and distribution were selected as measurable attributes of eelgrass to represent
estuarine condition. Existence of eelgrass is one of the best indicators of estuarine quality, and
the presence of a diverse aquatic community (e.g., greater species diversity and abundance was.
found in eelgrass beds compared to adjacent unvegetated areas in Waquoit Bay and Nauset Marsh
on Cape Cod (Valiela et aL, 1992; Heck et al., 1989)). Measures of quality and density were not -
chosen for eelgrass attributes because of the greater difficulty in obtaining information on plant
species composition, shoot density, and blade stature. Although these variables influence physical
structure, food availability, and physical suitability of these areas for fish, in the absence of
toxicity, the presence of eelgrass beds is die best indicator of the presence of a diverse estuarine
aquatic community. Both eelgrass and several eelgrass dependent and commercially important
species have declined precipitously since the 1950s.
2JL2L2 Resident and Jiranife Estuarine FtafishSp^
The estuarine finfish community contains resident and transient, and demersal and pelagic
species/ Fifty-two species have been collected in Waquoit Bay. Of these, mummichug, striped
killifish, tidewater silverside, fourspine stickleback, and rainwater killifish constitute 35 percent of
the total taxa, and dominate the abundance (46 percent) and biomass (41 percent) of the overall
ftnfish community (Ayvazian et al., 1992). Part-time residents represent a composite of estuarine
spawners (e.g., winter flounder and tautog); marine species that are estuarine visitors (e.g., sand
lance, summer flounder, and American pollack); nursery species or young-of-the-year (e.g.,
winter flounder juveniles; mullets, juvenile tautogs* menhaden. Atlantic silversides, bluefish, and
bay anchovy); and adventitious species that have a more southern distribution but lack an
apparent estuarine dependence (e.g., ladyfish, halfbeak, and crevalle jack).
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Resident and nursery fmfish were selected for the assessment endpoint because of their
importance to commercial and recreational values, their •significance to the aquatic community,
and their susceptibility to localized impacts on habitat .quality. Finfish are susceptible to hypoxic
and anoxic conditions (e.g., summer anoxia or hypoxia may impact winter flounder juveniles and
mummichugs, objective 1) and toxic contaminants (objective 2). The loss of eelgrass habitat
encompasses a decrease in coverage, a decrease in density of stems, the displacement of eelgrass
by macroalgae, or the conversion of eelgrass meadow to open bottom with sand or mud
sediments. Macroalgal mats are less suitable than eelgrass as a refuge for ftnfish, and the bottom
of the macroalgal mat may be hypoxic (objectives 4 and 6). Diversity and abundance of resident
and nursery ftnfish were selected as attributes because these measures represent the existence of
conditions that support survival, reproduction, and recruitment (objective 3), arid some data are
also available. Feeding, hiding, reproduction, and recruitment would be important attributes to
measure in nature studies.
Commercially harvested marine and estuarine adults are not included. They are
susceptible to offshore as well as inshore stressors and therefore reflect more regional impacts
resulting from harvest pressure, coastal eutrophication, and long-term climate change. These
groups were not selected as part of the assessment endpoint because nursery species and
year-round resident finfish are better indicators of localized impacts on habitat quality. If resident,
and nursery species are protected, it is assumed that marine species will also be protected from
habitat degradation.
2^13 Clam and Other Benthic Invertebrate Diversity, Abundance, and Distribution
Clams and other benthic invertebrates in Waquoit Bay provide major food sources for
resident and transient finfish and water-dependent wildlife. Hardshell and softshell clams currently
support an important recreational and commercial fishery. Scallops are no longer harvestable.
The benthic community can be adversely affected by loss of eelgrass, toxic and hypoxic
conditions and macroalgal mats (objectives 1,2, and 5). Shellfish and other benthos are also
sensitive to the degree of sedimentation hi breeding areas, the presence of critical habitats such as
eelgrass beds and wetlands (objective 4) and the extent of recreational and commercial harvesting
mortality, including catch and by-catch (objective 5). The presence of eelgrass beds and sufficient
water quality are thought to be the critical elements for supporting the appropriate habitat to '
maintain and promote a diverse and abundant estuarine benthic faunal community.
Scallops are principally found in eelgrass beds and hardshell and softshell clams inhabit
sandy open areas. Since these species are found in different bottom habitats, their abundance and
distribution are a good reflection of ecosystem function.- Although scallops are specified in
management objective 4, they were not explicitly selected as an assessment endpoint because their
numbers fluctuate widely in nature, and the absence of scallops cannot be interpreted to mean that
the known environmental requirements for scallops are not being met Since many benthic species
prefer eelgrass meadows as a habitat, the eelgrass-associated benthos community is being used to
represent the ecological requirements for scallops.
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2.2.2.4 Migratory Brook Trout and Aiewife Herring Reproduction
Migratory fish, including anadromous brook trout and alewife herring, use the Waquoit
Bay watershed as breeding grounds. Migratory fish provide for a highly valued commercial
fishery that has been in decline. The Quashnet River was a prized trout stream, with large
populations of anadromous or "sea run" brook trout or "salters" in the 1800s. By 19SO, industrial
and then agricultural demands had destroyed their breeding habitat It has taken years of effort by
Trout Unlimited and the Massachusetts Division of Fisheries and Wildlife to reestablish breeding
habitat in about 1.5 miles of the river. The trout species that rely on this river for spawning are
susceptible to water quality changes. They depend on swiftly flowing, cold waters that are high in
dissolved oxygen. Alewife herring, which travel to John's Pond to spawn, rely on sufficient water
depth to traverse the bogs near the pond. Drops in the water table or reduced flow can prevent
access to spawning areas. The Quashnet River and the ground water that feeds it might be tapped
for drinking water, leading to changes in water quantity while urban-development could lead to
further water quality problems;
Trout and alewife are sensitive representatives for other migratory finfish. Protecting the
ability of migratory finfish to reach freshwater rivers and ponds and find habitat and water quality
appropriate for spawning and egg survival meets the management goals for streams and ponds
(objectives 2 and 9). Reproduction of migratory fish was selected as the attribute because the key
function that the freshwater portions of the watershed provide to migratory fish is reproductive
habitat This attribute is particularly susceptible to the types.qf stressors likely to impact
migratory fish in mis watershed.
2.2.2.5 Freshwater Stream Bentfaic Invertebrate Diversity and Abonda
Stream benthic invertebrates serve as a needed food source for migratory and resident fish.
Like migratory fish, benthic invertebrates need swiftly flowing, highly oxygenated, high-quality
water for their habitat Benthic invertebrates ate excellent indicators of water and sediment
quality because they spend most of their life cycle in the stream (often in restricted locations or
habitats) and are particularly susceptible to toxics (objective 2), eutrophication effects (objective
8), and sedimentation. Societal value is based on the value of native species (objective 9) and the
support the benthic aquatic community provides for fish species (objective 3).
2^2.6 Freshwater Pond Trophk Status
Changes in the tropic status of kettle ponds serve as an indicator of water quality and
directly affect ecosystem function (objective 8). The susceptibility of ponds to increasing nutrient
loads makes this assessment endpoint the best indicator of pond shifts from oligatrophic to
eutrophic status and also addresses community interest in recreational use of the ponds for
swimming, fishing, and aesthetic enjoyment
2,2.2,7 Water-Dependent Wildlife Species. Feeding and Nesting Habitat
Many avian species, including the piping plover, least tern, and roseate tern, nest or forage
along the barrier beaches of Waquoit Bay. Other important wetlands in the Waquoit Bay
watershed include die salt marshes surrounding the bay and its tributaries, the coastal ponds, and
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the shorelines of Ashumet and Johns Ponds. Waterfowl are the most societally important wildlife
solely dependent on wetlands for breeding, feeding, and migratory needs. Within the ponds, a
high diversity of phytoplankton and abundant invertebrates provide food for finfish which, in turn,
are prey for osprey. Several avian species that use the ponds are of special concern or threatened,
including the marsh hawk and grasshopper sparrow. These species have high societal value.
They are susceptible to toxic pollutants originating from MMR, cranberry bogs, and urban
development (objective 2). They are also susceptable to habitat loss, both from direct destruction
of habitats, and toxicological and hydrological changes that may influence habitat type, quality,
and quantity. Significant numbers of bird and mammal species use wetlands and freshwater
resources around the ponds and rivers for feeding and nesting. Maintenance of supporting
wetland habitats was considered appropriate for meeting management objective 10.
2^2.8 Bacterial and Contaminant Content of Fish and Shellfish
The aquatic community of fish and shellfish provides significant recreational and
commercial benefits to humans and other organisms in the watershed. Increasing incidents of
shellfish bed closures to harvesting because of high bacteria counts are of considerable concern to
commercial and recreational interests in the watershed (objective 5). Increasing evidence-of
malformations in resident freshwater fish in ponds now being contaminated by ground water
plumes flowing from the MMR Superfund site are cause for concem,although evidence is
preliminary {objective 2). Contamination is expected to increase and might be a problem now.
2.23 Overlap of Assessment Endpoints. and Their Application to the Risk Assessment
These assessment endpoints are used to represent ecological values in the watershed that
support management goals. During their selection considerable discussion occurred to determine
whether this set of endpoints was sufficient, redundant, or excessive. Several endpoints may be
considered redundant but were not eliminated before conceptual model development because of
possible insights their use could provide during hypothesis generation and model construction.
The team recognized some redundancy but felt that the set best covered the diversity of ecological
values and stressors impacting me watershed.
Selection of which assessment endpoints to follow through to analysis occurred during the
development of the conceptual models and in the planning of analyses. In some cases only limited
data or information is available on an assessment endpoint so for the purposes of this risk
assessment, that assessment endpoint can only serve as a focal point for conceptual model
development However, for planning future research the assessment endpoint serves a significant
function in defining what research needs to be done hi the watershed.
2.3 CONCEPTUAL MODEL DEVELOPMENT
The conceptual models developed for the Waqiioit Bay watershed represent a series of
risk hypotheses about the relationships between particular stressors and ecological effects
expected to be observed in each assessment endpoint Models were developed at several levels of
complexity and were done interactively. The general watershed conceptual model (Figure 2) is a'
broad representation of relationships among human activities in the watershed (sources), the •
stressors believed to occur as a result of those sources, and ecological effects likely to occur in
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WAQUOIT BAY WATERSHED CONCEPTUAL MODEL
Agriculture Atmosphere Residential Dev. Industry
Marine Activities
to
K-»
o
Shoreline
Protection
and
Modification
(RapuifMndM
Sedimenti
I....
O
5
to
8
1
o
n!
O
3)
O
I
Figure 2. Waquoit Bay waUAfaed conceptual model.
-------
Conceptual Model continued, page 2.
U)
/SW + sed/«
TO!** r\
Sedkneni Nutrients
of Floods
and Low
Algal Garth
(macroalgae
phytoplankton.
•piphyte.
Stream Gravel
FW
Berthto
Invertebrates
(Pond,
Stream
Estuarine
Benthtc
Invertebrate
Community
Migratory
Fish
Streams
Finfish
Community
tophte
State
to//F1plng
Indices //teastTem/ /IB1
/
/Fry
/ indices,
Clam.
Scattop
C»lcn
bundance
of Resident
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o
I
§
O
O
03
D
I
Figure 2. Waquoit Bay watershed conceptual model, continued.
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each of the. assessment endpoints. Shown within the conceptual model are possible measures to
evaluate response. Second-level models focus on particular assessment endpoints and show
multiple stressors, potential exposure pathways and expected ecological responses.
2J.I Watershed Conceptual Model
The watershed-level conceptual model diagram illustrates connections among sources of
stressors, stressors, effects, and assessment endpoints in the Waquoit Bay watershed. The diagram
is organized around system stressors. Each stressor has a coded line type that illustrates a
pathway connecting its sources to effects and endpoints. Each of the components of the model is
represented by a different figure to aid interpretation (see key). This is a broad-based model that
provides a framework for the risk assessment and an overview of ecosystem processes. The
diagram shows only stressors and effects thought to occur in the Waquoit Bay watershed. It does
not show the relative importance or magnitude of the stressors or effects. More detailed
conceptual models were developed to evaluate multiple stressor effects and exposure pathways
for specific assessment endpoints. These were generated as a result of detailed risk hypothesis
development (see Section 2.3.2)
Key to Models:
Figure Componenf
Rectangle Source of stressors
Ellipse Stressor
Double-tine diamond Primary ecological effect
Diamond Secondary ecological effect
Parallelogram Measurement
Octagon Assessment endpoint
Shown at the top of the model are five major human activities (agriculture, atmospheric
deposition, residential development, industry, and marine activies). Within each of these major
activities are one or more specific activities that serve as sources of stress in die watershed. For
example, residential developmeit results in housing and road construction, installation of septic
systems, installation and maintenance of lawns and gardens, and construction of wells.
For each activity or source identified there are potentially one or more stressors thatmight
exist in the watershed system. For example, nutrients serve as one major system stressor in
WaquoiL However, sources of nutrients in this system are many and include fertilizer application,
industrial emissions, automobiles; lawn and garden maintenance, septic systems, impervious
surfaces, and sewage treatment plants. The next level in the diagram shows predicted and
observed ecological effects .believed to result from exposure of the ecosystem to stressors.
Represented here are several cascading effects. For example, nutrients can lead to algal growth,
which contributes to increased chlorophyll in ponds and siltation, shading, and low dissolved
oxygen in estuaries. These responses can lead to loss of eelgrass, suffocation of aquatic
communities, habitat loss, and eutrophication.
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The potential adverse effects of one stressor are shown to affect one or many assessment
endpoints. Nutrients can be traced to six assessment endpoints including freshwater benthic
invertebrates, trophic status of ponds, pond fish community, eelgrass habitat, and estuarine
benthic and finflsh communities. In some cases indirect effects might not be represented here, but
would be shown in the specific pathway conceptual models foe a single assessment endpoint or a
single stressor (e.g., although water-dependent wildlife are not connected to the nutrient matrix,
nutrients affect the fish and invertebrate communities on which wildlife feed). Assessment
endpoints for which appropriate data could prove difficult to obtain are identified later in the
process but are represented in the conceptual model.
The watershed-level conceptual model diagram features seven stressors:
Toxic chemicals. Sources of toxic chemicals are agricultural pesticides, atmospheric
deposition (metals and organics from automotive and industrial emissions), suburban lawn and
garden chemicals, point sources (solvents and fuel in die MMR plumes), impervious surfaces
(metals and hydrocarbons in road and roof runoff), and docks and marinas (metals and
hydrocarbons from antifouling substances and boat motors). The toxic chemicals may affect
aquatic animal life: migratory fish, pond fish, freshwater benthic invertebrates, estuarine benthic
invertebrates, and estuarine fish.
Altered flow. Stream flow might be altered by flow control structures built for cranberry
bogs, by groundwater depletion from well pumping, and by runoff from impervious surfaces.
Altered flow can change the timing and magnitude of floods and low flow, as well as the amount
of fish and invertebrate habitat available in streams, and riparian wetland area. Organisms
dependent on these habitats might be adversely affected: migratory fish, stream benthic
invertebrates, and wetland-dependent wildlife.
Resuspended sediments. Several watershed activities might contribute suspended
sediment to the estuary or resuspend sediment in the bay. Activities mat might contribute
sediment include construction (all) and impervious surfaces (particulates in impervious runoff);
activities.that may resuspend sediment in the bay include construction of docks, boating,
dredging, and shellfishing. Suspended sediment might contribute to siltation and shading of
eelgrass.
Nutrients. Sources of nutrients include agricultural and suburban fertilizers, atmospheric
deposition of nitrogen oxides, domestic septic systems, wastewater treatment facilities, and
impervious surfaces. The primary effect of nutrient loading is growth of algae, principally
phytoplankton in the ponds and macroalgae and periphyton in the estuary. Increased algal
production increases the trophic state of the ponds andean contribute to hypoxia in both ponds
and the estuary, with ultimate effects on invertebrates and fish. In the estuary, algal growth
contributes to shading of eelgrass by macroalgae and periphyton, and eventual replacement of the
eelgrass by algae. Loss of eelgrass may .in turn cause cascading effects on estuarine invertebrate
and fish communities. A more detailed conceptual model of eelgrass loss is shown in Figure 3 and
a detailed conceptual model of the fmfish community changes is shown in Figure 4.
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Figure 3. Eelorass conceptual submodel. E-214
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Stmaun
Ecotogfetf
EMMtt
(pMCflflL dtatributtont
Figure 3. Eelgrass conceptual submodel, continue)
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O« N«u»»y Oeoxnn?
MMR9 WSMf)
Figure 4, Finfish community conceptual submodc
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• Oraogng
• QMS. n«r.
Tone
I FnWi ODfiviturtjr I
1AbmtamimoiMnHrJ
/
/
Figure 4. Finfish community conceptual submodel.
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Habitat alteration. Several activities in the watershed result in alteration of aquatic
habitats. Construction activities might cause temporary or permanent habitat changes if the
construction is in or hear an aquatic habitat Docks and piers are a permanent alteration of the
aquatic habitat Boating, dredging, and shellfishing might directly disturb eelgrass habitat and
injure plants. Beach protection (jetties and groins) changes sediment transport and beach
dynamics, potentially altering the barrier beach habitat These alterations to streams, wetlands,
barrier beaches, salt marshes, and eelgrass beds might adversely affect the organisms in those
habitats.
Disease. Eelgrass wasting disease (Labyrimhula) is the only stressor in the conceptual
model with no known anthropogenic source. It has a direct effect on eelgrass cover and hence
has indirect effects on estuarine invertebrates and fish.
Harvest pressure. Harvest pressure includes fishing for freshwater fish, estuarine fish,
anadromous fish, and shellfish and affects only those groups.
For the purpose of focusing on specific parts of this watershed, Figure 5 shows these
pathways for the stream component, Figure 6 shows pathways for the pond component, and
Figure 7 shows pathways for the estuarine component Bach of these pathways was created
based on assumptions, or risk hypotheses, about how stressors are affecting or are expected to
affect targeted assessment endpoints. They were derived from available information on the
watershed gathered early in the problem formulation process and on a continuing basis, from
ecological theory on how systems function, and from relationships established in other watersheds
that are expected to be consistent from one geographic area to another where similar systems
exist
233, Risk Hypothesis Development
The watershed conceptual model illustrates that each stressor might affect several
endpoints and each endpoint might be influenced by several stressors. Since assessment eridpoints
provide the focus for this risk assessment and the intent of the assessment is to assess the risk of
multiple stressors on a particular assessment endpoint, the following discussion on risk hypotheses
is divided by endpoint This approach provides the foundation for evaluating the cumulative and
combined risk of more than one stressor. To understand how assessment endpoints are being
affected by these stressors, however, it will be necessary to evaluate alternative exposure
pathways of a stressor from different sources. Stressor pathways are evaluated through additional
conceptual models.
The following risk hypotheses are expressed as-narratives about how. assessment endpoints
might become exposed and respond to one or more stressors. Background information that
supports these hypotheses is available in Appendix E.
23.2.1 Eelgrass Habitat Abundance and Distribution: Risk Hypotheses and Conceptual
Models
The conceptual models and risk hypotheses for the eelgrass habitat abundance and
distribution assessment endpoint include sources and stressors, cascading ecological effects, and
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WAQUOIT BAY STREAM CONCEPTUAL MODEL
Agriculture Atmosphere Residential Dev. Industry
Automotiw
Emlutoni 1
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WAQUOIT BAY ESTUARY CONCEPTUAL MODEL
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Figure 7. Waquoit Bay estuary conceptual model, .continued.
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response pathways. Eeigrass habitat is the common assessment endpoint for each of the source-
to-response pathways represented in the model. Common measures (eeigrass habitat cover and
extent) apply to each pathway. These measures are depicted outside the direct source-to-
assessment endpoint pathways because they represent the result of ecological response rather than
a direct measure of the response or attributes of the response pathways.
The following discussion is separated into two parts. The first provides predictive
hypotheses about the effects of primary stressors depicted in the watershed conceptual model
(Figure 2). These hypotheses and predictions are then followed by a descriptive conceptual model
and hypotheses on the multiple pathways for loss of eeigrass from the variety of sources of these
stressors and source-to-response pathways. Each of these pathways is illustrated in the eeigrass
habitat conceptual submodel (Figure 3).
Stressor Hypotheses
The watershed conceptual model (Figure 2) contains five primary stressors for eeigrass:
nutrients, sediments, physical.alteration of habitat, toxics, and disease. Based on conclusions
drawn from available information, multiple stressor effects have caused eeigrass to decline over
the last 40 years. Each stressor has multiple sources. Reduction of one stressor or source is not
likely to be sufficient for reestablishing eeigrass in the bay, although nutrient reduction is a
necessary prerequisite.
Nutrients. Increased nitrogen loading in estuarine waters causes shading from excess
growth of macroalgae, phytoplankton, and epiphytes. Historical and steady state inputs of
nitrogen to ground water .will continue to influence algal growth for up to 100 years. Additional
development in the watershed will add to this nitrogen loading. Light attenuation in-shallow
estuaries might not be great enough to eliminate eeigrass altogether, but continuing inputs of
nitrogen from current activities will prevent eeigrass recovery. Sub-bays with the greatest
nutrient loads will have more macroalgae and less eeigrass. Those sub-bays with less nutrient
loading will have less macroalgae and more eeigrass.
Suspended Sediments. Shadmg from resuspended sediments caused by physical
disruption of bottom sediments results hi decreased growth and the death of eeigrass plants.
Physical Alteration of Habitat Available habitat for eeigrass has changed and will
continue to change .because of (1) loss of appropriate habitat from dock construction; (2)
mechanical disruption from clam digging, boat props, and moorings, which cut eeigrass blades or
uproot and kill eeigrass plants; and (3) subdivision of the meadow as a result of eeigrass death
caused by mechanical disruption, disrupting community integrity and altering meadow
composition.
Toxics.. Toxics cause physiological stress on eeigrass plants, leading to slow growth.
This could exacerbate effects from other stressors.
Disease. Slime mold acts synergistically widi reduced.light to decrease eeigrass growth,
and water currents transport infected eeigrass blades, broken by physical disruption, to new areas.
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Predictions
• The replacement of eelgrass beds with fast-growing macroalgae will continue unless
the amount of nitrogen entering the bay is reduced. Reestablishment of eeigrass will
require reduction of nutrients.
• Reestablishment of eelgrass from reduced nutrient loading will occur only over a long
time period to account for the time travel of nutrient laden ground water to the Bav.
• Reduction of nitrogen is a necessary but not sufficient requirement for eelgrass re-
establishment Habitat alteration from physical disruption will need to be reduced or
confined to specific areas to allow teestablishment
• The co-occurrence of wasting disease, toxics, and reduced water clarity might result in
the complete elimination of eelgrass from the Waquoit Bay system. Complete
elimination means that replanting might be the only means of reestablishing eelgrass
meadows.
Conceptnaj) \fodei
The primary stressors have multiple sources. The opportunity to reduce these sources of
stressors are of primary management concern. The hypotheses below describe the eelgrass-
specific conceptual model to illustrate the multiple ways eelgrass can be lost from this system and
to provide insights on where management action is most feasible... This discussion provides the
basis for the conceptual model diagram shown in Figure 3.
.Disease. The marine slime mold, Labyrinihuia, causes "wasting disease." It is
opportunitistic and likely to cause infection in stressed populations in more saline waters.' The
infection of eelgrass located in higher-salinity areas of .Waquoit Bay leads directly to loss of
eelgrass by death of infected individuals. Exposure pathways for the disease are not known;
however, salinity influences infection such that eelgrass in areas of lower salinity is less likely to
be infected. These areas are important for reestablishment.
Nutrients.. Nitrogen is the primary nutrient of concern in the estuary. Nitrogen
potentially enters the bay through multiple pathways including ground water discharge, air
deposition, point source discharges, and impervious surface run-off. Exposure pathway analysis
by Valiela et at (1992) suggests that the principal pathway is via groundwater from septic system
inputs (Appendix E, Figure E-6). The resulting increase in surface water and sediment nitrogen
concentrations leads to increased growth of epiphytes, macroalgae, and microalgae. Epiphyte
growth on eelgrass leaves decrease light availability by shading and increases leaf effective surface
area, causing possible weighting and burial of eelgrass from increased siltation on leaves.
Increased growth of macroalgal mats leads to direct shading of eelgrass and decreased light
penetration. Phytoplankton growth increases water turbidity, decreasing light penetration to
eelgrass. Algal growth also contributes to increased organic sediment, which might be
resuspended by physical disruption (below) and contains a reserve of nutrients.
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Construction and Recreational Activities. Boat propellers impinging on bottom
sediments; dredging; construction of docks, piers and marinas; clam raking; mooring; and erosion
in the watershed cause increased suspended sediments or resuspension of bottom sediments.
Hydrographic conditions (e.g., wave amplitude, frequency, and direction; current velocity) act as
forcing functions that can increase water turbidity. Turbidity increases shading and decreases
light penetration. This leads to reduced eelgrass photosynthesis, growth decline, and death of
eelgrass. It also causes siltation onto eelgrass leaves, compounding the effect of epiphyte growth
discussed in the previous pathway.
Docks and Piers. Docks directly block light and reduce available habitat for eelgrass,
leading to reduced eelgrass photosynthesis and loss of shaded eelgrass. Docks and piers also
provide the basis for increased boat traffic, which leads to disturbance of sediments and increased
turbidity in areas around the docks and piers. Great River, a tributary in the Waquoit Bay
watershed, will show a loss of eelgrass in correlation with increased dock building.
Lawn Care, Agricultural, and Industrial Activities. Care of residental and commercial
property lawns, agricultural activities (e.g., cranberry bogs), and industrial activities (e.g., MMR)
in the watershed are a source of a variety of toxic chemicals. These may cause physiological
stress in eelgrass, leading to reduced growth and death of eelgrass plants. Exposure pathways
and effects from these sources of potential stress are little known.
Boat Propellers, Clam Rakes, Moorings. Boat propellers, clam rakes, and moorings
directly disrupt bottom sediments, causing physical alteration of habitat and mechanical
destruction of eelgrass blades, resulting in death or stress to the plant Repeated activities without
sufficient recovery time will result in decline in eelgrass beds because of direct loss of plants, and
from the creation of small patches, increasing vulnerability to other stressors (e.g., storm events).
Boating activities that chum up bottom sediments will increase the amount of suspended
sediments, increasing turbidity and decreasing light penetration to eelgrass beds. Epiphytes
growing on eelgrass blades provide good depositional surfaces for suspended solids and can
weigh down the eelgrass blades causing them to sink to the bottom where they die from
insufficient light or suffocation (Short, 1989).
2.32.2 Resident Estuarine Finfish Diversity and Abundance: Risk Hypotheses and
Conceptual Model
The conceptual models and risk hypotheses for the resident finfish diversity and abundance
assessment endpoint include sources and stressors, cascading ecological effects, and response
pathways. Resident finfish is the common assessment endpoint for each of the source-to-response
pathways represented in the model. Common measures (diversity and abundance) apply to each
pathway. These measures are depicted outside the direct source-to-assessment endpoint
pathways because they represent the result of ecological response rather than a direct measure of
the response or attributes of the response pathways.
The following discussion describes the principal stressors represented in the watershed
conceptual model (Figure 2) and specific predictions to. consider. This is followed by the
presentation of the finfish conceptual model and descriptive hypotheses about relationships
depicted in the model.
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Stressor Hypotheses
Multiple stressor effects are resulting in lowered reproductive success of adult resident
finfish, as well as lower survival of eggs and juvenile finfish. Each stressor has multiple sources.
Determining the relative contribution of these stressors will be important for setting management
priorities.
Nutrients. Increased nitrogen loads alter finfish diversity and abundance through
excessive macroalgal growth, which results in (1) loss of eelgrass habitat for breeding, feeding,
and hiding and (2) hypoxic and anoxic conditions that result in physiological stress, exposure to
predation, and suffocation.
Suspended Sediments. Increased sediment hi the water column alters finfish breeding,
feeding, and hiding habitat by (I) reducing growth of eelgrass, (2) covering available habitat, (3)
smothering eggs and juveniles, and (4) reducing feeding success of visual predators.
Physical Alteration of Habitat Development of land adjacent to prime finfish nursery
habitats causes a direct loss of available nursery areas and contributes to sediment and nutrient
loading in the vicinity of nursery areas. Direct physical alteration of nursery areas from dredging,
boat prop disturbance,and changes in flow patterns from inlet changes and armoring of coasts
alters quality or removes habitat from potential use.
Toxic Chemicals. Multiple sources of toxic chemicals from pesticide application, air
pollution, lawn maintenance, point source discharges, nonpoint runoff and chemicals used on
docks and boats combine to alter survival and reproduction of juvenile finfish. Stress from
hypoxic and anoxic conditions exacerbates the effects of toxicity.
Harvest Pressure. Recreational fishing removes reproductive adults from the population
of resident finfish. Although offshore fishing alters the available adult stock returning to Waqupit
Bay, this reflects regional impacts and no hypotheses are pursued for this portion of the finfish
community.
Predictions.
Loss of eelgrass habitat (from multiple stressors) will favor species associated with
open-water, nonvegetated habitats such as Atlantic silverside, adult summer flounder,
and winter flounder as well as rock crabs and green crabs, over those species
associated with vegetated habitats such as tidewater silverside, juvenile summer
flounder, grass shrimp, rainwater killifish. juvenile tautog, fourspine stickleback, and
striped killifish.
Loss of eelgrass habitat and projected changes in the functional aspects of the finfish
community will result in (1) increase-in omnivores; (2) decline in top carnivores; (3);
shift from benthic to pelagic habitats; (4) decline in total number of species, estuarihe
spawner species and estuarine resident species; (5) increase in disease incidence and
morphological abnormalities; (6) decrease in eelgrass habitat quality prior to physical
habitat loss; (7) increase in dominance of eutroohic tolerant species where dominance
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.represents the ntlmber of species accounting for 90 percent of the total numbers or
biomass;-and (8) higher fish density and biomass (abundance) in medium-quality
compared to low-quality habitats (Deegan, 19 ).
« Increasing contaminant inputs from recreational activities and future toxicity from
contaminated ground water plumes from MMR will increase abundance of tolerant
species and increase incidence, of fmfish malformations and disease.
• Anoxia and hypoxia will slow growth, maturation, and reproduction of fmfish (e.g.,
Atlantic silversides, juvenile winter flounder, and juvenile tautogs versus
mummichogs),
Conceptual Model
The primary stressors have multiple sources. The opportunity to reduce these sources of
stressors are of primary management concern. The hypotheses below describe the finfish
conceptual model to illustrate the multiple ways finfish diversity and abundance are likely .to
change and to provide insights on where management action is most feasible. This discussion
provides the basis for the conceptual submodel diagram shown in Figure 4.
Recreational and Commercial Fishing, Estuarine and offshore fishing remove
reproductive aged fish from the population. This mortality will exaccerbate other losses to adults,
juveniles and eggs from other stressors and can change the dynamics of the finfish community
resulting in shifts in competition, feeding patterns and other behaviors.
Nutrient Loading. Nutrient loading increases algal production in the estuary. Increased
production leads to increased organic matter loads and increased respirational oxygen demand,
resulting in periodic oxygen stress and occasional fish kills on warm, cloudy, calm days in
summer, when the bay may stratify. Nutrient loading also might lead to loss of eelgrass (see
eelgrass conceptual submodel Figure 3). Eelgrass beds are a nursery area for juvenile finfish;
hence, loss of eelgrass may lead to declines in fish recruitment and fish populations.
" Toxic Chemicals. Toxic chemicals from lawns, agriculture, impervious surfaces and the
MMR plumes might cause direct morbidity and mortality of resident finfish in all age classes
although some age classes could be more susceptible. Toxic chemicals also might lead to loss of
eelgrass (see eelgrass conceptual submodel Figure 3). Eelgrass beds are a nursery area for
juvenile fmfish; hence, loss of eelgrass might lead to declines in fish recruitment and eelgrass
dependent fish populations.
Sediments, Physical Alteration and Disruption. These stressors all can lead to loss of
eelgrass (see eelgrass conceptual model Figure 3). Eelgrass beds are a nursery area for juvenile
finfish; hence, loss of eelgrass can lead to declines in fish recruitment and fish populations. These
stressors might also lead to loss of salt marshes through direct alteration. Salt marshes are
spawning and nursery areas for several estuarine finfish and forage fish, hence, loss of salt marshes
might lead to declines in fish recruitment and fish populations.
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23.23 Conceptual Models and Hypotheses for Other Assessment Endpoints
Development of conceptual models ar.d risk hypotheses for the remaining six assessment
endpoints is ongoing, but they are not ready for presentation at this time. The models developed
for eeigrass and ftnfish provide a basis for determining how best to present information and
develop the process. The conceptual models represent considerable information, but in many
cases data are not available at this time to conduct an evaluation of posed hypotheses and
predictions for these two endpoints. They are presented to allow managers and scientists in the
watershed to consider potential research that will provide the basis for pursuing a more complete
risk assessment. Further analyses of available data will allow the Team to refine hypotheses for
the these and the other endpoints.
2.4 ANALYSIS PLAN
The large number of assessment endpoints identified in this risk assessment required a
preliminary evaluation of overlap among endpoints. A comparative risk analysis was used to help
define which stressors, assessment endpoints, and relationships should be examined further. To
do this preliminary analysis, stressors were ranked in terms of potential risk to all resources in the
watershed, as well as risk to individual endpoints. Those stressors and endpoints. deemed most
important are featured here, although comparable risk hypotheses have been developed for each
of the assessment endpoints identified. The following analysis was conducted by the risk
assessment team and is considered preliminary, ft requires additional verification and peer review
by scientists in the watershed.
2.4.1 Comparative Risk Analysis
To conduct a comparative risk analysis, a process called "fuzzy set,** which is based on
best professional judgment (Harris et al., 1994; Wenger and Rong, 1987), was used. This
approach was applied to each endpoint and stressbr. The fuzzy set approach is a decision analysis
method for ranking alternatives according to multiple criteria. Applied to ecological risk
assessment (Wenger and Rong, 1987; Harris et al., 1994), stressors are the alternatives and the
assessment endpoints are the criteria. The analysis then ranks the stressors in order of greatest
overall contribution of risk to the endpoints.
An impact matrix for the Waquoit Bay watershed, derived from the conceptual model, is
shown in Table 5. Each column represents a single endpoint, and each row a single stressor from
the conceptual model Every connection in the conceptual model from a ressor to. an assessment
endpoint is represented by a non-zero cell in the effect matrix (Table 5). --marine and freshwater
elements are combined in this matrix, as they are hi the conceptual model. Each cell contains the
effect of a stressor on an endpoint, on an ordinal scale from 0 (no effect) to 3 (severe effect)
(Harris et al., 1994): For example, the effect of nutrients on eeigrass habitat is given a 3 (severe,
indirect effect), but the effect of physical alteration on eeigrass habitat is given a I (slight effect)
(Table 5). The effect of toxic substances on pond trophic state is given a 0, because toxic
substances in the watershed are not thought to affect pond trophic state (no pathway in the
conceptual model).
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Table 5. Hypothesized effects matrix; each ceil represents relative effect of a stressor on an
endpoint.
Suspended
sediments
Rankings were obtained by the difference method, as explained in Wenger and Rong
( 1987) and Harris et al. (1994). The effects of each stressor 7 on endpoint k are subtracted from
the effects of stressor i :
« *» - */* (Harris et at 1994).
The matrix R = (rs) is an m x m matrix of the sums of the above differences for ail endpoints fc
r9 = SD&j). U = 1. 2, .... m
(Harris et al., 1994). See Wenger and Rong (1987) for further formulas. The row sums of matrix
R were used for ranking the stressors; the largest row sum was the dominant stressor (Table 5,
Base Case). Using the impacts of Table 5, nutrients were ranked first, followed by physical
alteration and toxic chemicals, then harvest and flow, and finally suspended sediments and disease
(Table 6).
Stressors can be weighted by me persistence of the stressors if their input is removed.
Persistence of stressors was ranked on a scale of 1 to 5, where 1 represents almost no persistence,
and 5 is an effect that lasts indefinitely (Table 7). Altered flow and physical alteration received a
persistence score of 5 because they are permanent changes that do not reverse themselves. Toxic
chemicals and nutrients received a persistence score of 3 because of the time delay in ground
water travel to reach water bodies. Thus, if sources of either toxics or nutrients were
stopped, substances remaining hi the ground water would still .affect water bodies for some time.
Suspended sediments, harvest pressure, and disease received a score of 1 because they are aH
relatively nonpersistent; Le, if fishing is stopped, there is no "residual" harvest pressure.
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Table 6. Stressor ranks under three scenarios.
Suspended sediments
Results of the weighting are also in Table 6 (weighted column). When weighted, the three
stressors tied previously for third place (altered flow, toxics, and harvest pressure) differentiated,
into third to fifth place (Table 6).
Table?. Relative duration of stressors.
Nutrients
Physical alteration
Altered flow ' •
Toxic chemicals
Harvest pressure
Suspended sediments
Disease
3
5
5
3-
1
1
1
Stressors may interact with one another by exacerbating other stressors (Harris et al.,
1994). interactions among the stressors are shown in Table 8. Bom members of an interacting
pair of stressors receive a score because bom must be present for the interaction to work.
Interaction scores were set at 1 because they are plausible, hypothesized relationships, with no
information on their relative strength or actual existence. Nutrients can enhance the effects of
both suspended sediments and disease by causing excess organic floe that can be resuspended, and
shaded eelgrass may be more susceptible to disease. Excess organic floe contributes to
sedimentation. Toxic chemicals may stress eelgrass plants so that they are more susceptible to
disease.. The resultant rankings reflecting both weighting and interaction (Table 6, rightmost
column) were the same as the weighted scenario only.
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Table 8. Interaction among stressors.
Altered flow
Toxic chemicals
Harvest pressure
Suspended sediments
Disease
0
Ranks were very similar among the three models, showing that the hypothesized effects
matrix (Table 5) was robust to changes in persistence and interaction. Nutrients were always
ranked first; physical habitat alteration was always ranked second. Suspended sediments and
disease were always ranked last Altered riverine flow, toxic chemicals, and harvest pressure
were tied in the middle in the unweighted scenario, but when weights were applied they
differentiated from each other. The robustness of the rankings was due primarily to the" number of
endpoints affected by each stresson Nutrients and physical alteration each affected six endpoints,
and nutrients had two strong effects on two assessment endpoints (eelgrass habitat and pond
trophic status).
The comparative risk analysis presented here must be regarded as preliminary because the
effects matrix (Table 5) has not at this writing been reviewed and agreed to by experts and
knowledgable persons on ecological effects in estuaries. In the absence of quantitative data on
the relative magnitudes of effects of the different stressors, expert consensus is required
2.42 Developinent of a RegtoflalModd of Eelgrass Response to Natrie0tU>adlng
Submerged aquatic vegetation (SAV) is a sensitive indicator of eutrophication in estuaries
(Dennison et aL, 1993) and is easily monitored with aerial photography. As described in Section
2.2, eelgrass beds are preferred habitat of juvenile scallops, and are a nursery and feeding area for
estuarine fish. Eelgrass beds can be identified and quantified from aerial images and can be
distinguished from other S AV (e.g., Ruppia, Codiiari) and from macroalgae and bare sediment
For these reasons, eelgrass cover, was selected as a measurement endpoint for eelgrass habitat,
estuarine finfish habitat, and estuarine benthic invertebrate (including scallop) habitat
Although it has been known for some time that nitrogen loading contributes to estuarine
eutrophication and loss of SAV hi Waquoit Bay and other estuaries of Cape Cod (e.g., Costa
1988; Valiela et aL 1992; D'Avanzo and Kremer, 1994), quantitative relationships between
nitrogen loading or nitrogen sources on the one hand, and the biological response of SAV on the
other have not been developed for estuaries such as Waquoit This is in part because nitrogen,
unlike phosphorus^ is not conserved (le., N may be denitrified or fixed) and because in estuaries,
unlike in lakes, water residence time is more difficult to estimate. The objective of this analysis
will be to develop the link between estimates of modeled nitrogen loading and predicted
ecological effects in the estuary.
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estuaries of Buzzard's Bay. and to larger estuaries such as Tampa Bay (Tampa Bay NEP. 19951.
Therefore, it should also be successful for the estuaries of the South Shore of Cape Cod.
2.4.2.2 Models for Estimating Nitrogen Loading
There are currently three models (CCC, WBLMER. and BBNEP) of nitrogen loading for
Cape Cod estuaries. Each predicts the total N loading from measured watershed variables.
including the amount and distribution of residential septic systems, impervious surfaces, lawns,
natural vegetation, and other sources. The models differ in assumptions on N transformations in
ground water and the fate of atmospheric N deposition on land, but all three result in substantially
similar estimates of total N loading to the estuary (Cadmus, 1995). A fourth model (Sham et al.,
1995) takes into account the time required for nutrient-laden groundwater to travel to surface
waters, where it can contribute to eutrophication. Newly constructed septic systems and
discharges may not contribute to nutrient loading for several decades, depending on the hydraulic
travel time from the source to a surface water body (Sham et al., 1995). By analyzing
construction dates of discharges and travel times. Sham and colleagues, estimated that current
loading to Waquoit Bay is approximately 70 percent of the ultimate loading from existing
structures, and that 90 percent of the ultimate loading is reached in approximately 10 years (Sham
et al., 1995).
The analysis here will take into account ground water travel time, as elucidated by Sham
et aL The Sham et al. analysis used the CCC model as its base and also required a complete land
parcel ^atfth^re for the Waquoit watershed, with date of construction for each parcel, as well as
estimation of ground water flow velocities from the extensive well data in the Waquoit watershed.
A similar analysis at the same level of detail for all watersheds in the model would be prohibitive.
Such a level of detail is probably unnecessaiy.because the three base models for N loading have an
estimated uncertainty of 25 to 40 percent (M. Geist, personal communication). Given the
uncertainty of the base models, it should be possible to develop coarser estimates of travel time
and ccflstniction date and stffite within fe
Given the prediction mat 90 percent of ultimate nitrogen loading is reached in 10 years
(Sham et aL, 1995), travel time can be approximated by estimating areas representing travel times
of 0 to 5 years, 5 to 10 years, and greater than 10 years. On a map, these would appear as
concentric bands around an estuary or parallel to a stream. A first-order approximation would be
to estimate the distance traveled by ground water in 5 years (approximately I km in Sham et al.,
1995) and apply that distance to ail watersheds in the analysis. Land use and dates of .
construction can be estimated for each of the three travel bands from a CIS database, and one of
the N loading models can then be applied to estimate total N from each of the three source areas.
Z4iZ3 Cap* Cod Estnvy ChnnH'tfrf*a*tMi
Approximately 90 semi-enclosed estuaries and subestuaries are on the south shore of Cape Cod
and the islands with a relatively narrow outlet to the sea or to another estuary. Some wiU prove
to be inappropriate for a regional model (e.g., too smalt top isolated, too open), but
approximately 50 estuaries, might be sufficient for development of a regional model. Eelgrass
cover has been digitized from the'Massachusetts DEP aerial images and integrated into the CIS
database for all of these estuaries.
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Characterization of each estuary and subestuary will require assembly of a GIS database
for Cape Cod and the islands. The existing Mass GIS database will provide boundaries,
coastlines, streams, place names, land use, and census data. The Cape Cod Commission has
delineated ground water watersheds for the Cape. The principal activities here will be digitization
of bathymetry from the NOAA charts and characterization of each estuary and subestuary using
GIS. Each estuary and subestuary will be characterized as follows:
Biological (from Mass DEP aerial images):
• Eelgrass cover (percent of total area, percent of area < 4m deep)
• Observations of Ruppia, Codium, and algae in the estuary
Physical (from Mass GIS and NOAA charts bathymetry):
area
maximum Q^ pti^
mean depth
inlet width
inlet length
inlet maximum depth
inlet mean depth
water body type outside of inlet (sound, 1° estuary, 2° estuary)
Total channel length from estuary or subestuary to sound
Watershed and Land Use:
• Watershed area (ground water). Ground water watersheds have been delineated for
Cape Cod estuaries by the Cape Cod Commission.
• Land use (total area hi each land use class)
• Population
• Area, land use, and population within S-year ground water travel time to tidal waters
• Area, land use^and population within 5-to-10 year ground water travel time to tidal
waters .
• Area, land use, and population greater than 10 year ground water travel tune to tidal
waters ...
• Distribution of new construction (< 5 yr old, < 10 yr old) in a watershed
2A2A Eeterass Response Model for Cape Cod Estuaries
Following characterization of each estuary, data.will be plotted to determine whether
relationsHips be delected from scatterplots. The scatterplots will help determine the most
appropriate model: linear, curvilinear, or categorical approaches such as logistic orloglinear
models. At least four alternative models will be examined: models using land use directly as a
predictive variable, models using estimated nitrogen loading as the predictive variable, and models
with and without an estuarine retention time parameter.
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Model 1 (simple land use)
y = a +• bx, +> or, + dx, + e , where
y =- eelgrass cover
.c, = dwellings per unit estuarine surface area in the 0-5 yr travel band
t, = dwellings in the 5- 1 0 yr travel band
.t. = dwellings in the > 10 yr travel band
Model 2 (estimated N loading)
y = a + bx + e , where
x s area! nitrogen loading estimated from one of the N loading models, taking into account the
three ground water travel bands and estimated proportion of new construction in each.
Modeb3and4
Models ! and 2 may be improved with an estuarine retention time parameter, the Vollenweider
parameter (Reynolds, 1984; Costa etaL, 1995):
, where
/„ s average hydraulic retention time •
z * mean depth
Retention time is difficult to estimate in estuaries- because of highly variable wind-induced
and tidal mixing during a tidal cycle (Geyer and Signell, 1994). Retention time can be bounded at
the upper limit by freshwater inflow assuming no tidal exchange (treating the estuary as a lake),
and at the lower limit by freshwater inflow, plus tidal inflow assuming complete mixing every tidal
cycle. Actual mean retention time will be somewhere between these two extremes. A fust-order
approximation for these small estuaries will be to assume 50 percent mixing every tidal cycle, and
calculate retention time accordingly. Alternatively, it has been suggested that macroalgae,
because they are held fast to one spot, intercept nutrients that are carried past them in water
currents and hence are not affected by estuarine retention time. If retention time is unimportant,
then the retention time models will perform poorly relative to models land 2.
2A.2JS Uncertainties Associated with the Eelgrass Response Model
* *
An objective of risk assessment is to characterize uncertainty and its sources that may play
a role in prediction of risk. Sources of uncertainty in the ecological risk assessment include:
• Alternative hypotheses.. Other explanations or interactions operating that were not
addressed or that might impede attainment.of management goals might be 'operating.
• Model uncertainty, m me case of me estoarine analysis, there are three competing.
nitrogen loading models, each of which will be examined for a "best fit" to the eelgrass
response data. The resultant "best fit" model is empirical and does not necessarily
reflect underlying mechanisms; it seeks only the best fit to the data. However, aslong
as the predictions of the best fit model hold, it is sufficient for management
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• Data uncertainty. Data uncertainty includes data collection methods, adequacy of
sample size, random sampling error, and measurement error. Random error (including
natural variability) is part of the data distribution and can be analyzed with empirical or
Monte Carlo methods.
Uncertainties Associated with Factors Affecting Eelgrass
Predictions from the estuarine portion of the risk assessment will include risk of continued
eelgrass habitat loss, or, conversely, probability of eelgrass habitat recovery for given nutrient
management scenarios. These predictions and probabilities will derive from the empirical models
developed in the analysis phase on eelgrass response to predicted nutrient loading. The response
model will not cover several alternative and interacting hypotheses that may also contribute to
eelgrass loss or may prevent eelgrass habitat recovery. Thus, the models are intended to predict
necessary, but not necessarily sufficient, conditions for eelgrass recovery.
Eelgrass requires relatively clear water (Secchi depth = 1-2 m); it will grow in salinities
greater than 10-15 ppt, and sediments composed of fine sands or muddy sands (Batiuk et at.
1992). Necessary and sufficient conditions for eelgrass growth and recovery in Waquoit Bay are:
• Low nitrogen concentrations that are not toxic to eelgrass (<1 MM; Burkholder, 1992)
and that permit eelgrass growth while limiting rapid growth of Cladophora and
Gracilaria. dadophora is characteristic of eutropnic habitats. In Sage Lot Pond, a
subestuary of Waquoit Bay, Cladophora and GracUaria were limited when nitrate
concentration was less than 1 /zM in the. water column and when sediment interstitial
ammonia was less than 1.5 fM (Peckol et aU 1994). Similarly, Batiuk et al. (1992)
recommended nitrogen concentrations less than 0. IS mg/L DIN (<2.4 /jM) to limit
phytoplankton growth in eelgrass habitat of the Chesapeake Bay.
Achieving low nitrogen loading to Waquoit Bay will require some sort of nitrogen
source control* as well as a sufficient lag time to allow nitrogen currently in the ground
water to be flushed out Groundwater travel times hi the watershed might be several
tens of years, depending on distance from a source to a water body (Sham et al.,
1995). Management scenarios to be analyzed will include an estimate of the lag time
necessary for changes in nutrient supply to take effect in the estuary. A secondary
time lag is the pool of nitrogen in the decomposing organic matter, which is thought to
be approximately 3 years' supply (Tampa Bay NEP, 1995). The organic nitrogen pool
may therefore require 3 to5 years to equilibrate to a lower level, but this appears to be
negligible compared to the time lag in the supply rate.
• Absew» of raaoodgal and epiphytic growm capable of overgrowmg and shading
eelgrass. Eutrophication and excess algal production are reversible if nutrient
availability is reduced. Achievement of low nitrogen loading and a reduced nitrogen
pool in the estuary win result in reduced algal growth.
• Low turbidity and tow resuspension of fine organic matter. Because of the sandy-soils
of Cape Cod, mineral turbidity (sift and clay) is not a problem in Cape Cod waters. In
Waquoit Bay, fine organic matter from decomposing algae is resuspended by wind,
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tide, and boat wakes. This organic matter can settle on eeigrass leaves, enhanced by
the surface roughness of epiphytic algae. The epiphytes and the organic sediment
shade the leaves and can inhibit eeigrass growth. Although this mechanism of
sediment entrapment by epiphytes has been proposed to contribute to SAV loss (e.g..
Kemp et al., 1983: Short 1993), it has never been demonstrated to operate in the field
or in the laboratory.
Excess organic matter is a consequence of excess production due to nutrient
enrichment. If the supply of organic matter is reduced, by reducing nutrient loading
and primary production, then the organic matter pool would eventually decline due to
decomposition, burial in the* sediment, or export from the system. Thus, as long as
nutrient loading is reduced, organic matter will decline with it, perhaps delayed by a
time lag of 3 to 5 years (Tampa Bay NEP1995).
• Appropriate sediment for eeigrass growth. Eeigrass can grow in a variety of
sediments, including mixtures of sand and mud, fine sands, and other particle sizes
(Orth and Montfrans, 1984; Bathik et al., 1992; Burkholder et al., 1992). The
sediment has previously been appropriate for eeigrass growth.
• Appropriate salinity for eeigrass growth (>10-15ppt). Available information indicates
that Waqnoit Bay has not freshened.
• Eeigrass propagules. Existing eeigrass root stocks and seed banks might have been
exhausted in the years of decline Natural recolonizan'on is a random event and
depends on nearby seed sources. The remnant eeigrass populations in the subestuaries
Hamblin and Jehu Ponds, as well as offshore populations, may provide seeds to
Waquoit Bay, but there is no way of knowing when such colonization might occur.
Aerial images (1994) show large and extensive eeigrass beds in Vineyard Sound just
. outside the Waquoit Bay inlet Alternatively, eeigrass may be planted to restore
meadows, if habitat requirements have been met Restoration (planting) of habitat mat
meets eeigrass ecological requirements (light, salinity, substrate) has met with mixed
success (up to 80 percent survival but variable; Batiuk et aL, 1992).
Modd Uncertainty
The exposure-response models result in an empirical uncertainty, expressed as. the
confidence intervals of the models. Another type of uncertainty is model uncertainty, or
indeterminacy, because it is not known which loading models are correct, or even which one gives
the best estimates of nitrogen loading and its sources. In the risk assessment framework, the
confidence intervals of the eeigrass response models represent uncertainty of ecological effects,
and the indeterminacy of the loadings models represent uncertainty of exposure.
Data Uncertainty
The standard error of predicted values is'the uncertainty of .the exposure-response model
The exposure model,-in turn, has uncertainty due to uncertainty of its. input variables. The output
uncertainty can be simulated with a Monte Carlo approach and yields a distribution of the output
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variable, N loading. The N-!oading distribution is then combined with distributions ot" other input
variables to the exposure-response model and the uncertainty of the prediction to yield an overall
uncertainty of the combined model. The uncertainty can be expressed as a confidence interval or
a cumulative distribution. A predicted distribution (uncertainty) for each of the models is then
obtained. These uncertainties can be combined to yield an overall uncertainty that includes model
indeterminacy among the three or four models.
The final models and their estimated uncertainties can be used to predict the probable
consequences of specific management scenarios (e.g., effects of complete planned buildout;
effects of sewer installation in selected portions of the watershed, effects of improved septic
'systems, effects of lawn fertilizer ban). They can also be used to estimate the probability that a
management action will fail to achieve its target, and thus, how much effort is necessary to obtain,
for example, 90 percent probability of achieving the objective.
2.4J Potential Future Analysis for Other Stressors
The preliminary comparative risk analysis identified nutrient loading as the dominant
stressor in the* watershed, This risk assessment will explicitly analyze estuarine nutrient loading,
leaving freshwater nutrient loading, habitat alteration, and other stressors for future, more
comprehensive analysis. Drections this future analysis could take are discussed below.
2.4J.1 Quantitative Relative Risk
Experience with ecological risk assessment and with biological assessment has shown that
multiple stressor problems often involve stressors with vastly different magnitudes of effects. If
one or more stressors can be shown to be negligible compared to the dominant stressors, the
problem can be simplified and the risk assessment can be focused on those stressors which are
significant
This risk assessment is proceeding on the basis of the preliminary fuzzy set ranking of
stressors described above, which concluded that nitrogen loading is the principal stressor of the
estuarine component of me system. The ranking, while establishing priorities, does not permit an
overall simplification of the problem because there is no indication of the relative magnitudes of
effects. For example, is estuarine nutrient loading 10 percent more important than habitat
modification or irit 10 times more important?
Several analytical methods are available to develop multiple stressor screening. At the
simplest level, these could include extrapolation of laboratory information or extrapolation of
information from similar systems. Because it is a simple screening-type analysis, the dangers of
extrapolation are considered to be tolerable, as in the quotient method used in toxic risk
assessment The values compared (as ratios) could be the estimated loss of selected endpoints
attributable to each stressor individually.
2.4,3.2 Pond Nutrient Loading
Ashumet and Johns Ponds are subject to nutrient enrichnient (primarily phosphorus) from
ground water and nonpoint runoff.
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Objectives
• Characterize expected trophic state of Cape Cod ponds not subject to discharges,
residential septic seepage, and suburban lawn and road runoff.
• Characterize current trophic state of Ashumet and Johns ponds from ongoing MMR
studies.
• Estimate risk of further eutrophication of the ponds based on projected increases in P
loading, using a Vollenweider eutrophication model.
2.4 JJ Physical Habitat Alteration
Physical habitat alteration has the greatest potential effects on freshwater stream
components and on water dependent wildlife. Effects are well-known: removal of a habitat
results in removal of species dependent on that habitat It is generally not reversible unless the
original habitat is restored. Physical habitat alteration in the Waquoit watershed includes beach
protection, which changes the dynamics of barrier beaches; road and subdivision construction in.
nontidal wetlands: and road and development alterations of streams. Except for beach protection,
the continuing extent of habitat alteration in the Waquoit watershed is poorly known. Salt marsh
is currently protected from further encroachment by development; freshwater wetlands, less so.
Habitat of the Quashnet River has been restored, but not in the Childs River. It is not known
whether further habitat alteration will take place in these rivers.
A second component is temporary habitat disruption, with no permanent habitat loss. If
the disruption is more frequent and more severe than the ability of the system to recover, it can
become a permanent loss. Disruption is often a question of overuse, such as by mountain bikes,
off-road vehicles, or boats. The principal concern in Waquoit has been boat propellers cliroinz
eelgrass-and preventing its recovery.
Qbfecthres
• Measure the present and historical extent of suitable habitat for beach and dime nesting
'birds.
• Quantify the abundance of plovers and terns in the watershed.
* Correlate hflHfitf and bird flbfffi'dancg
Development of Habitat Loss-Response Relationship Between Avian Habitat and
Species Abundances. Habitat loss is well known to cause irreversible loss of species dependent
on the habitat for a key part of their life cycle. Birds are particularly vulnerable to loss of nesting
areas, and fish:are vulnerable to loss or degradation of spawning areas, the U.S. Fish, and
Wi(dlife Service, the National Biological Service, and the Massachusetts Audubon Society might
have information on suitable habitat for beach and dune nesting birds, estimates of past habitat
extent, and bird counts or nest counts in the area. If the information is available, it-may be
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• possible to determine trends in available habitat and nesting activity over time and in relation to
land use and population measurement endpoints.
Eelgrass Disruption. A stress-response relationship between eelgrass and boating
activity is more difficult to develop because data are more difficult to obtain and because boating
activity and nutrient loading are likely to.be collinear in the Cape Cod region. Information from
sites with high boating activity but low nutrient loading, and sites with high nutrient loading but
low boating activity will be needed. A place to look for reports might be Florida, where there are
extensive shallow regions without serious eutrophication problems, but with potentially high
boating activity (e.g., Florida Bay, parts of Tampa Bay, other Gulf Coast embayments).
Alternatively, what information would be required to answer this in the future? A simple
experiment would be to cordon off several areas from boat traffic after nitrogen management is
implemented. Eelgrass regeneration within the fenced areas but not outside would indicate that
boat traffic is significant in inhibiting eelgrass regrowth.
2.4.3.4 Other Stressors
All other stressors identified in this risk assessment ranked lower in priority in the
comparative risk analysis. The MMR toxics assessment will analyze human health risks due- to
toxic substances in the ponds, and an ecological risk analysis is still needed. For the other
stressors, too few data exist for further analysis at this time. Possible hypotheses that would be
addressed in later phases of this risk assessment include:
• Altered riverine flow. Altered flow in the streams from ground water removal,
cranberry cultivation, and storm water runoff decrease stream base flow and increases
stormflow, and increase the risk of habitat degradation for anadromous fish and
invertebrates in the streams of the watershed,
• Toxic chemicals. Toxic chemicals in ground water plumes and from lawn and
suburban stormwater runoff increase the risk of loss of freshwater and estuarine fish
and invertebrates.
• Harvest pressure. Excessive harvest pressure increases the risk of loss of commercial
and recreational fish and shellfish in the estuarine and freshwater systems of the
Waquoit Bay watershed.
* Suspended sediments. Suspended sediments, primarily from resuspension of organic
floe by boat wakes hi the estuary, increases the risk of loss of eelgrass due to
sedimentation of the floe on the eelgrass blades and increased light attenuation, and
therefore also increases the risk of loss of estuarine fish and invertebrate habitat.
A future analysis approach would be to assess the extent and magnitude of each of the
stressors, to address the question of exposure of the system to the stressors. For example, for
altered flow, this might include determining the stormflow hydrography of the most altered stream
(Child's River), and comparing it to less altered streams such as the Quashnet or other rivers.
Alteration of base flow could be addressed by analysis of USGS gauge readings. USGS might
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have determined stormilow'hydrographs for streams with a gauging station. If flow alteration is
minor, even in the most heavily altered stream, flow alteration is a negligible problem..
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Department of Environmental Management, Waquoit, MA.
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Proceedings, pp. 41-47. EPA 823-R-95-002. U.S. Environmental Protection Agency,
Office of Water, Washington, DC
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Wright, S3. 1987, An assessment of the biological and physical changes in the Quashnet River
caused by a stream rehabilitation project Master's Thesis, Northeastern University,
Boston, MA.
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Biological interactions and their potentM importance for seafloor credibility. In Estuarine
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Assessment of environmental suitability for growth ofZostera marina L. (eelgrass) in San
Francisco Bay. Aquat Boi 39:353-366.
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APPENDIX A
LIST OF PARTICIPANTS IN THE WAQUOIT BAY WATERSHED CASE STUDY
Waauo11 Bav Risk_Assessment WorkaroiiD
Suzanne Marcv
Patti Tyler
Maggie Geisi
David Dow
Jeroen Gerritsen
Chock Spooner
Conchi Rodriguez
Vicki Atwell
Technical Panel Chair, U.S. Environmental Protection Agency. Office of
Water
U.S. Environmental Protection Agency, Region I
Waquoit Bay National Estuarine Research Reserve
National Marine Fisheries Service, Northeast Fisheries Science Center
Tetra Tech, Inc.
U.S. Environmental Protection Agency, Office of Water
U.S. Environmental Protection Agency, Office of Prevention,
Pesticides and Toxic Substances
U.S. Environmental Protection Agency, Office of Research and
Development
Waauoit Bav Risk Assessment Contributors
Edouard Eichner
Joe Costa
Ivan Valiela
Charles CosteHo
Heidi Clarke
Tom Cambareri
Lynn Feldpausch
Jack Gentile
Chi-Ho Sham
Cape Cod Commission
Buzzards Bay National Estuary Program
Boston University
Massachusetts Department of Environmental Protection
Yale University
Cape Cod Commission
U.S. Environmental Protection Agency, Region t
U.S. Environmental Protection Agency, Office of Research and
Development
The Cadmus Group, Inc.
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APPENDIX B
NEWSPAPER ADVERTISEMENT AND ARTICLE
ON WAQUOIT BAY WATERSHEDCASE STUDY
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APPENDIX C
RESULTS OF THE WAQUOIT BAY PUBLIC MEETING
A public r'orum was held September 21. 1993 at the Waqomt Bay Yacht Club. Participants
contributed to the identification of what was valuable in the watershed (Table C-1) and to the
identification of the principal stressors that might be placing those valuable resources at risk
(Tables C-2 and C-3).
Table C-l. Environmental values/concerns that should be protected in the Waquoit Bay
watershed.
Environmental Values/Concerns That Should Be Protected
Open Space
Non-Economic Values
Historical/Political Perspective
Traditional Lifestyles
Scenic Views
Education
Indigenous Wildlife
Flyway Integrity
(migrating waterfowl)
Recreation
(swimming)
Food Resource Safety
Tourists
"Historical" Bay Ecosystem Structure
"Quality of Life"
(pleasant sensual experiences, natural
noise, smells, sights, night
sky/darkness, freedom to enjoy, visual
beauty, access to natural beauty,
wildlife, vegetation, pheasants,
skunks, clean water, clean air)
Shellfishery
Shellfishing
"Clean" Water
Shoreline
Human Serenity
.Marshland
Upland-Marsh Ecotone
"Habitat-
Recreational "Atmosphere"
Water Quality
Rushing Rates
Ak Quality
Questions on General "Health" of Existing
Ecosystem(s)-Health As Measured, (re:
only identified "active" stressor)
Washbum Island
Human Health and Domestic Animals Health
(re: lyme disease)
Habitat
Striped Bass
Navigation
Ground Water Quality
Eel Grass
Wildlife
Marine Organisms
Finfishery
Finfishing
Herring
Aquifer Integrity
.(flow rates)
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Table C-2. Types of stressors affecting the Waquoit Bay watershed.
Stressor
Dredging
Commercial Overfishing
Outside of the Bav
Commercial Trawling;
Water Withdrawal & Effect of
Gcoundwater/Surface Water
Relationship
Non-Native Species
Bacterial Population
Acid Rain
Ignorance,
Lack of Education
Nutrient Loading
— Fertilizers for Lawn, Golf
Courses and Agriculture
— Sewage Treatment, Plants
— Acid Rain
— Road Runoff
— Boats
— Livestock & Pets
—Wildlife (Waterfowl)
Boat Prop Disturbance
Shellfishing
—Raking
—Plunging
Waterfowl
Boat Wake Disturbance
Chemical
X
X
X
X
Physical
X
X
X
X
X
x
X
Biological
X
X
X
X
X
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Stressor
Overpopiuation
— Uncontrolled Growth
— Uncontrolled Access
Habitat Loss
— Loss of Ecotone Between
Marsh and Upland
— Trampling of Marsh by
Boats and People
— Unmonitored Campling
— Upland Development Resulting in
Sedimentation and Hydrologic
Changes
Lack of Values
Non-Nutrient Runoff
Man-Made Noise
Historic Fuel Dumping
— Residual Contamination within
the Atmosphere
Wet Deposition
Dry Deposition
Regional Air Transport and Patterns
Ignorant Tourists
Apathy
Fertilizers
— Insecticides
—Pesticides
Global Wanning
Sea Level Rue
Catastrophic Storms
— Nor'Easter
— Hurricanes
Boating Impacts from
Shade and Anchorage
Docks and Piers
Boat Bottom Paint. Oil and Fuel
Chemical
X
X
X
X
X
X
.•
X
Physical
X
X
X
X
X
X
X
X
X
X
Biological ' I
x :
X '•
X
X
X
X
X
X
X
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Stressor
Boat Speeding
Shoaiing>Loss of Flushing
within Bav
Building/Development
Careless Disposal of Chemicals
Uncontrolled Drainage
—•Road Runoff
— Agricultural
Lead Shot
Cresote on Pilings
Copper Arsemate on Pilings ,
Underground Storage Tanks
Lyme Disease
—Ticks. Deer. White-Footed
Mouse '(Vectors)
Lack of Management
Short-Term Economic Values
Otis Air Force Base
Willful Destruction of
Natural Resources
Lack of Enforcement
Chemical
X
X
X
X
X
X
X
X.
X
X
Physical
X
X
X
X
X
X
X
X
Biological
i
X !
X 1
X
X
X
X
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Table C-3. Waquoit Bay watershed stressors and ecological effects.
Source
Septic systems.
fertilizers.
atmospheric
deposition
Septic systems
Septic systems
Nutrient input
Nutrient input
Nutrient input
Nutrient input
Macroalgal growth
Stressor
Nitrogen
Pathogens
Fecal conforms
Shading by
macroalgae
Shading by
macroalgae
Increase in
macroalgal
growth
Increase in
macroalgal
growth
Icreased
respiration of
macroalgae
Type
Chemical
Biological
Biological
Physical
Biological
Biological
Physical
Chemical
Ecological Effects
Increase in macroaisae and
phytoplankton growth !
Introduction of pathogens and
fecal coliforms to surface
water
Shellfish bed closures
Alteration of substrate and
decrease in light attenuation
Major fauna! alterations in
benthic and fish communities
Alteration of macroalgal
• .^f
species composition
Loss of habitat for submerged
aquatic vegetation
Loss of spawning sites for fish
Loss of hiding places and
protection of fish
Loss of scallop larvae settling
habitat
Change in water coloration
Decrease of dissolved oxygen
within the water column
An increase in respiration rates
in combination with a
tempgfatme and cloud cover
increasesanoxic 'events
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Source
Macroalgal growch
Macroaigal growth
Unleashed dogs,
gulls, crows, red
fox. and eastern
coyote
Mute swan
Fertilizers and
septic systems
Marinas and piers
Gasoline, motor oil.
Automobile and
boat engines'
' Massachusetts
Military
Reservation
(Otis Air Force
Base)
Stressor
Increased
respiration of
macroalaae
Competition by
macroalgae
Wild predators
Introduction of
exotic species. '
Phosphorus
Antifouling
chemical
leachate
Organic
compounds
acetone,
benzene,
naphthalene,
petroleum
hydrocarbons.
polychlorinated
biphenylsand
creosote
*Methyleoe
chloride, cw 1,2'
dichloroemy-
lene.U,K .
trichloroethane,
trichloroethy-
lene, perchloro-
ethane, 1,2-
DBA, toluene,
etfaylbenzene,
xylene in Sergou
Phase I Held GC
Screening Data
Type
Biological
Biological
Physical and
biological
Biological .
Chemical
Chemical
Chemical
Chemical
Ecological Effects
Mortality within benthic
invertebrate and fish
populations
Loss of eelgrass habitat
Disturbing nesting areas for
two endangered
species — piping plover and
least tern and the threatened
roseate tern
Displacing native waterfowl
species
Negative biological effects on
organisms in contact with it
7
?
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Source
Massachusetts
Military
Reservation
(Otis Air Force
Base)
Lawns, golf
courses/cranberry
bogs
Road deicing salt
- Landfill leachates
?
Stressor
DCE. TCE.
PCE. in Ashumet
Valley
Groundwater
Plume
Need
information
Need
information
Unrecorded
dump sites (need
more
information)
Metal*—
arsenic.
cadmium.
chromium.
copper, lead.
mercury.
molybdenum.
nickel, silver.
zinc
Hurricanes or
severe storms
Type
Chemical
Chemical
Chemical
Chemical
.
Chemical
Physical
. Ecological Effects
••>
7
Phytotoxicity, leaf fall
•
7
Looking into obtaining
information: from the EMAP
program
Flooding of upper estuary
-
Shoreline erosion
Altered tidal regime
Increase volume of water input
Sediment resuscension
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Source
Commercial
shellfishing
Construction
development
Otis Air Force Base
Global climate
change
Stressor
Seawalls and
jetties.
Boat propellers
Polar outbreaks
Raking and
plunging for
scallops
Filling wetlands
Thermonuclear
explosion
Sea level rise and
increase in
turbidity and
sediment loading
Type
Physical
Physical
Physical-
Physical
Physical
Physical
Physical
Ecological Effects
Major alteration of shoreline
dynamics
Sediment resuspension
Coastal erosion
Sediment buildup
Change in flushing rates
Rip-up vegetation
Sediment resuspension
Increased turbulence and
mixing in water column
Freezing of bay
Disturbing sediment
Resuspending nutrients
Increasing turbidity
Loss of marsh-uplands ecotone
Increase surface water runoff
(activities such as paving to
lead to an increase in surface
water runoff temperature)
Increase sediment loading
Alter groundwater flow
Intense heat and the end of life
as we know it
Flooding
' Alteration on coastline
increase in turbidity and
sediment loading
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Source
Stressor
Dredging
channels
Type
Physical
Ecological Effects
Sediment disturbance and !
increase in turbiditv
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APPENDIX D
WAQUOIT BAY MANAGEMENT GOALS MEETING
Attendees
Tom Cambareri
Bruce Carlisle
Joe Costa
David Dow
Perry Hlis
Tom Fudala
Jetpen Gerritsen
Steve Hurley
Chuck Lawrence
Sandy McLean
CariMelberg
Jo Ann Muramoto
MarkPatton
Pam Polloni
Bob Shennan
Jan Smith
Pani Tyler
Mary Varteresian
Brooks Wood
Rick York
Cape Cod Commission
Massachusetts Coastal Zone Management
Buzzards Bay National Estuary Program
National Marine Fisheries Service, Northeast Fisheries Science Center
Mashpee Harbor Master
Mashpee Planning Department
Tetra Tech, Inc.
Massachusetts Division of Fisheries and Wildlife
Cape Cod Commission
Citizens for the Protection of Waquoit Bay
U.S. Fish and Wildlife Service
Falmouth Conservation Commission
Otis Installation Restoration Program
League of Women Voters, Falmouth
Mashpee Conservation Commission.
Massachusetts. Coastal Zone Management
U.S. Environmental Protection Agency, Region 1
U.S. Fish and Wildlife Service
Monomoscoy Improvement Trust
Mashpee Shellfish Department
Concern
Ashumet - John's Pond Association
Ashumet Valley Property Owner's Association, Inc.
Association for the Preservation of Cape Cod
Atlantic States Marine Fisheries Commission
Bamstable County Department of Health and Environment
Cape and Islands- Coastal.Waters Steering Committee
Cape and Islands Self Reliance Corporation
Cape Cod Beagle Club
Cape Cod Commission (CCQ
Cape Cod Cooperative Extension Service
Citizens for the Protection of Waquoit Bay
Da vis ville Association
F. A. C. E. S.
Falmouth Rod and Gun Club
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WaqiiQJt Qay Concerned Organizations. Continued
Falmouth Condo Trast
Green Briar Nature Center
Mashpee Briarwood Association, Inc.
Massachusetts Audubon Society
Massachusetts Coastal Zone Management (CZM)
Massachusetts Department of Environmental Management (MADEM)
Massachusetts Department of Environmental Protection (MAOEP)
Massachusetts Department of Fisheries, Wildlife, and Environmental Law Enforcement
Massachusetts Heritage Society
Massachusetts Military Reservation (MMR)
Menauhant Harbor Association
National Oceanographic and Atmospheric Administration (NOAA) National Estuarine Research
Reserve System (NERRS)
NOAA National Marine Fisheries Service (NMFS)
National Science Foundation (NSF) Land Margin Ecosystems Research (LMER)
The Nature Conservancy
Seacoast Shores Owners Association
Shorewood Beach Owners
Sierra Club
South Cape Beach Advocates
The 300 Committee, Inc.
Town of Falmouth
Town of Mashpee
Town of Sandwich
Trout Unlimited
U.S. Army Corps of Engineers (COE).
U.S. Department of Agriculture (USDA) Soil Conservation Service (SCS)
U.S. Fish and Wildlife Service (USFWS)
U.S: Geological Survey
Wampanoag Tribal Council
Waquoit Bay National Estuarine Research Reserve (WBNERR)
Waquoit Bay Watershed Citizens Action Committee (formed of representatives of other groups)
Waquoit Bay Watershed Intermunicipal Committee
Waquoit Bay Yacht Club
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APPENDIX E
ASSESSMENT OF AVAILABLE INFORMATION
A summary of the assessment of available information was provided in Section 2.1 of the
Waquoit Bay Problem Formulation. The following material describes in more detail ihe
ecosystems at risk, reviews ecological effects that have been observed in the watershed, and
provides a preliminary characterization of stressors in the Waquoit Bay watershed based on
studies conducted in the watershed and elsewhere.
E.1 CHARACTERIZATION OF THE ECOSYSTEMS AT RISK
• ,
The Waquoit Bay watershed covers approximately 53 square kilometers (21 square miles)
and spans parts of the towns of Falmouth. Mashpee, and Sandwich on the south coast of Cape
Cod. Massachusetts. The watershed was first delineated by Babione (1990) and further refined by
Cambareri et al. (1992). Recent work by Brawley and Sham (in prep.) reinterpreted the
watershed delineation of Cambareri et al. (1992) to develop a three-dimensional model of the
drainage basin. The watershed covers 8 km (5 mi) from the head of the Bay to the regional
ground water divide in the vicinity of Snake Pond (Figure E-l). The Bay and its tributaries
encompass a total surface water area of 3.9 km2/389 ha (1.5 mi2). The major surface water
components of the watershed include the Waquoit estuary»two major rivers and several smaller
streams, freshwater ponds, and freshwater wetlands. Within the Waquoit Bay watershed are •
seven subwatersheds (Childs River, Sage Lot Pond, Quashnet River, Eel Pond, Head of the Bay,
Hamblin Pond, and Jehu Pond) and four ponds (Ashumet, Johns, Snake, and Flat). These
subwatersheds provide diverse habitats that support a variety of ecological communities, including
barrier beaches along the Atlantic Ocean, eelgrass beds, saltwater and freshwater marshes, erosion
and accretion areas, coastal sand dunes, brackish water ponds, fish spawning and nursery areas,
and wildlife habitat
E.1.1 Watershed-wide Characteristics
The Waquoit Bay watershed lies entirely within the Mashpee pitted outwash plain
(LeBlanc et aL, 1986), a geologically young landfonn composed of glacial materials deposited on
top of bedrock toward the end of the Wisconsinian Glacial Stage, about 12,000 years before
present (Oldate, 1992). Outwash plains were created by broad meltwater streams which size-
sorted the drift materials depositing the heavier boulders and pebbles near the glacial margin and
gravel and sands further away. Because Cape Cod is so young geologically, the glacial materials
have not been significantly altered, resulting in a generally sandy, porous soil throughout the area.
In addition to gravel and sand, there are clay and silt lenses; this finer grained material generally is
found in deeper sediments to the south.
The term "pitted "refers to the numerous kettle ponds dotting me landscape. Kettle ponds
mark the sites where blocks of ice were buried by sediment-laden meltwater streams beyond the
glacial margin. Johns Pond and Ashumet Pond are two examples of kettle ponds in the watershed
(HAZWRAP, 1995). Waquoit Bay, itself, may have originated as a kettle pond. The southern
margin of the bay was flooded by sea-level rise at the close of the Wisconsinan Glacial Stage,
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Subwatersbeds
1- Eel Pond
2-Childs River
3-QuashnetRxver
4 -Head of 4e Bay
5-HambliaPoixl
6-JchnPond
7 -Sage Lot Pood
A-AsttometPond
o * JOfiuS
C - Snake Pood
D'FIatPoaf
Figure E-l. Waquoit Bay watershed and subwatersheds (Banyley ad Sham, in prep.).
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when-the iee sheet'recreated, inundating low lying coastal areas and raising the water table inland
due to hydrostatic pressure at the saltwater-fresh water interface. The action of winds, waves and
currents continually eroded and displaced the loose glacial sand and gravel contributing to the
formation of coastal sand dunes, sea cliffs, barrier beaches and salt marshes. These processes
continue to alter the dynamic shore (Oldale. 1992).
Waquoit Bay's geology controls the region s hydrology, which is typical of a glacial
outwash plain. The Bay, 1.2 km (4,000 ft) wide and 3.4 km (11.000 ft) long, is a shallow estuary.
average depth of 0.9 m (3 ft), fed by freshwater streams and ground water with tidal exchange to
Vineyard Sound through two dredged and maintained channels, and a recent breach caused by
overwash during Hurricane Bob in August 1991 (Valiela et al., 1996). Fifty percent of the water
entering Waquoit Bay comes from the Quashnet and Quids Rivers, 23 percent from direct
precipitation, and 27 percent from ground water recharge in the watershed. Ground water in the
Cape Cod region is generally formed by precipitation. Ground water recharges the area upgrade
from the ponds and discharges from the downgradient portions of the ponds (Cambareri et al.,
1992). The rivers derive most of their water from ground water discharge, draining the shallow
surface aquifer. Ground water is forced to the surface as the permeable aquifer thins from north
to south in the watershed.
The unconsolidated sediments of Cape Cod make ideal aquifers-underground areas that
contain enough water to supply significant amounts of water for community use. The permeable
aquifer ranges from about 46 ra (150 feet) thick near Snake Pond, thinning to 9m (30 feet) near
Waquoit Bay (Garabedian et al., 1991; Cambareri et al., 1992). The porous soils support rapid
percolation of rain, nutrients, and contaminants into the subsoil and eventually to the ground
water. In recognition of the unique ground water characteristics of Cape Cod, the U.S.
Environmental Protection Agency declared this region a Sole-Source Aquifer in 1982, a
designation designed to facilitate protection of the water supply. In actuality, the Cape Cod
aquifer can be subdivided into six ground water "lenses'* or areas of elevated ground water;
surface features, such as rivers, separate the lenses and generally ground water does not flow
between lenses. The Waquoit Bay watershed lies within the Sagamore or western Cape lens of
the Cape Cod Aquifer (Guswa and LeBlanc, 1981).
The watershed's hydrology and habitats are influenced by its climate, which is similar to
that of other areas in the northeastern United States but typically has milder winters and cooler
summers due to surrounding ocean waters. January and February are the coldest months and July
and August are the wannestmonths. Fog may be common in the spring and summer and
humidity is typically high in the summer. Annual precipitation is between 107 and 112 cm (42 and
44 inches), ground water recharge is approximately 45 percent of the total precipitation. Snowfall
is variable from one year to the next but is close to 76 cm (30 inches) per year. Between October
and April the prevailing winds are northwest whereas from May to September winds come from
the southwest Hurricanes are most common in the late summer and early fall and "northeasters"
may occur in winter and early spring.
The surface water ecosystems in the lowlands and uplands of the Waquoit Bay watershed
contain several critical habitats identified by the* Association for the Preservation of Cape Cod
(VanLuven, 1991), including coastal plain pond shores, anadromous fish runs, salt marshes, *'
eelgrass, barrier beaches, and woodlands. Habitats hi the watershed are also affected by the
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southward-flowing cold Gulf of Maine waters and the northward-flowing warm Gulf Stream.
which mix off the coast of Cape Cod to form a biological transition zone between the Virginian
(temperate) and Acadian (boreal) biogeographic provinces (Ayvazian et al., 1992). This overlap
produces more diverse communities than occur in either province. The Waquoit Bay watershed
also lies near the Atlantic coast flyway, an important migratory corridor for many coastal and
arcttc-nesring birds, particularly shorebirds. as well as state and federally protected species. The
flora of the watershed include scrub oak and pitch pine forests (Bailey, 1995); forests covered
26SO ha (6S48 acres) of the watershed in 1990 (Appendix F). Among the state protected plant
species found in the watershed are the sandplain geratdia. Agalinis actua (endangered); the bushy
rockrose, Helianthuemum dumosum (threatened); the knotroot foxtail, Setaria genicidata (of
special concern); and the butterfly-weed, AscUplas tuberose, little ladies' tresses, Spiranthes
tuberosa, eastern lilaeopsis, LUaeopsis chintnsis. New England blazing star, Uatris borealis,
thread-leaved sundew, Droserafiliformis, vetchling, Lathyrus palustris, and wild rice/Zfczma
aquatic*, (on the watch list) (WBNERR, 1993). The following subsections describe in more
detail the physical characteristics and biota of each of the four major surface water components of
the watershed.
E.1.2 Waquoit Estuary
.Waquoit Bay is located at the southern margin of die watershed, protected from Vineyard
Sound by a barrier beach east of the main inlet to the Bay, South Cape Beach, and Washbum
Island, a barrier island to the west of the inlet (WBNERR, 1989). Water from the Sound enters
the Bay through two channels and the overwash breach mentioned above. Several brackish water
ponds (Sage Lot, Jehu, Hambtin, and Eel) connect to the Bay, Waquoit Bay is relatively shallow
and salt marshes occur hi some areas along the margins of the coastal poods and tributaries
(according to aerial interpretations of land use); saltwater wetlands covered 129 ha (319 acres) in
1990 (Cape Cod Commission, unpublished; Appendix F). Bottom habitats include areas of open
sand and mud, as well as patches of eelgrass.
Eelgrass (Zostera marina) is a rooted vascular plant that grows subtidally on mud to
gravel bottoms in zones of fast moving or quiet waters where salinity ranges between 20 and 32
parts per thousand. Eelgrass roots and rhizomes are believed to decrease erosion and increase
sedimentation, and eelgrass blades may act to promote deposition by interrupting water flow and
trapping suspended sediments, thus, adding to the available food within the meadow (Short, 1984;
1989). Eelgrass is highly susceptible to adverse changes in water quality conditions and requires
clear waters with ample light penetration for photosynthesis and suitable levels of nitrogen and
phosphorus nutrients (reviewed in Dennisbn* 1987; Zimmerman et aL. 1991; Murray et ah, 1992;
Dennison et aL, 1993; Submerged Aquatic Vegetation Work Group. 1995). Eelgrass provides
optimum physical and chemical environmental conditions ma protective habitat for many fishes
and invertebrates (Valiela et al., 1992; Heck et aL, 1989; Thayer et aL, 1989). A variety of
bryozoans, sponges, and hydroids attach to eelgrass blades; numerous juvenile ftnfish,
crustaceans, and shellfish inhabit eelgrass meadows. Decaying eelgrass leaves provide food for
the detritivores hi the benthic community as well.. Greater species richness and abundance has
been found hi eelgrass beds than in adjacent unvegetated areas hi Waquoit Bay and Nauset Marsh
on Cape* Cod (Valiela et aL, 1992; Keck et aL, 1989).
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The overlapping biogeographic ranges are evident in the waters of the estuary, with both
year-round residents and seasonal migrants in the finfish communities of Waquoit Bay. A 1968
survey reported that Waquoit Bay had the greatest diversity of finfish species in comparison to'
nine other Massachusetts estuaries (Curley et al., 1971). The resident species include such
species as mummichug (Fundulus heteroditus), striped killifish (Fundulus majalis), tidewater
Mlverside (Menidia beryllina), fourspine stickleback (Apeltes quadracus), and rainwater kitlifish
(Lucania parva), Of the 52 species collected in Waquoit Bay, these resident species comprise 35
percent of the total, with these species dominating the abundance (46 percent) and biomass (4 1
percent) of the overall finfish community (Ayvazian et al., 1992). Table E-l contains a list of
fishes found in the Waquoit Bay watershed
The part-time residents represent a composite of estuarine spawncrs such as winter
flounder (Pseudopleuronectes americanus), longhom sculpin (Myoxocephalus
octodecemspinosus), scup (Stenotomus chrysops), and tautog (Tautoga onitis); marine species
which are estuarine visitors, such as the sand lance (Amodytes americanus), summer flounder
(Paraiichtnys dentatta), and American pollack (Pollackius virens); nursery species or
young-of-the-year, such as winter flounder juveniles^ mullets (MugUcephaau), juvenile tautogs,
menhaden (Brevoortia tyrannys), Atlantic silversides (Menidia menidia), bluefish (Pomatomus
saltatrix), and bay anchovy (Anchoa mitchilli); and adventitious species which have a more
southern distributions but which lack an apparent estuarine dependence, such as ladyflsh (flops
saurus), hallbeak (Hemiramphus bmsiUensis), and crevalle jack (Caranx hippos). Alewives
(Alosa 'pseudoharengus) and biueback herring (Alosa aestvalis) cross Waquoit Bay on their
annual spawning migrations to fresh water, and larger fish such as bluefish and striped bass
(Morone saxitaUs) enter in pursuit of smaller prey fish. Many primarily marine fishes use the
estuary in the winter as a spawning and nursery ground. Bluefish, tomcod (Microgadus tomcod),
white hake (Urophycis tenuis), and pollock inhabit me bay as juveniles but are rarely present as
adults (Boesch and Turner, 1984).
Shellfish species harvested in die estuary include bay scallops (Argopecten uradians
irradians), found in the eelgrass habitat, and hardshell (Mercenaria mercenaria) and softsheil
(Mya arenaria) clams, generally found in the sand and mud habitats, respectively. The biota of
the. estuary also includes a variety of temperate and boreal species of planktonic and benthic algae
and invertebrates, providing food resources for the finfish and shellfish, as well as terrestrial and
avian wildlife in the watershed.
Numerous' shorebirds use the barrier beach and coastal saltmarsh as an important stopover
on their spring journeys north to breeding grounds in Canada and on their fall journeys south to
the southern United States, Central and South America. Shorebirds appearing in abundance in the
spring and fait on Waquoit Bay's barrier beaches include black-bellied (Squatarola squatarola)
and semipalmated (Charadrius semipalmatus) plovers; sanderiings (Crocethia alba); dunlin
(Calidris aipina); semipalmated (Ereunetes pusitlus), least (PisobiafiuicoUu), and western
sandpipers (Pisobia mmutillay, ruddy tumstones (Arenaria interpres); willets (Catoptrophona
semipaimatus); lesser (Totanusflavipes) and greater (Tetanus melanoleucus) yellowlegs; and
Sharp-tailed sparrows (Ammodramits
cudacutus), brack-crowned night-herons (Nycticorax nycricorax), snowy egrets (Leucophoyx
thuia), and mute swans (Cygnus olor) are found in the saltmarshes. Several species of buds that
use the waters as nesting or feeding grounds are state and federally protected species.
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Table E-l. Fishes of the Waquoit Bay Watershed
Genus/ Species- •
Common Name
Reference
Genus/Species
Common Name--
Reference-
Estoarine Residents
Opsanus lau
Funduius
heteroditus
Funduius majalis
Cyprinodon
variegaau
Lucaniaparva
Menidia berylUna
Menidia peninsula*
Pungitiio pungiliuf
Apeltes quadracus
oyster toadtlsh
mummichog
striped kiliifish
rainwater Itillifish
inland silverside
tidewater silverside
nlnespiae
stickleback •
i OttZSOlQC tXCiuCO&dC
Clupea hartngus
Brevoortia rynuuuu
AnchoamiteheUt
Microgadus tomcod
Strongylura marina
Menidia menidia
Atlantic herring
Atlantk menhadea
bayancoovy
A^«|^ir nocdl'tfiMv
Atlantic silvenide
A,C
A.CH
A.C
A.C
A,C
A
C
A.C
A.CH
Gasterosteus
acuUaaa
Casurosteus
.wheatlandi
Syngnaduafuscus
Menticirrhus
f/rmff[ff
Gabioscmabosd
Pkolis gunntiba
Myojoxephalus
aenaeus
Truucus masculaau
Sphotroidts
maculatm '
A
A.C
A
A.C
A.C
A.C
Pomatouuu saluinx
Tautogaonais
Tautogoutlma
adsptnta .
Mugil cephalus
PnudoiflfunHuctfs
Umphycistatuis
pjadfOOOQi (•nadromoui and calnlitmiii
Aag uilla rostntta
Alosa aestivalu
Alosa.
pseudoharengus
American ee4
blueback herring
aliewife
A.CH
A.C
A.C
At*t9M r/fiMu^rvWma
nivuu ju/niiijj»i«
Asmtna mordax
threespine
stickleback
blackspotted
stickleback
northern pipefish (in
eelgrass)
northern kingfish
naked goby
rock gunnel
sn*y . -
bogcboker
Dorthern puffer
A,C
A.C
A.C
- A.C
A
A.C
A,C
A.C
A.C
.
btucfisb
taotog .'
dinner
MrhMrfmnlla*
4U1JIT1J UMIIGI
winter flounder
white hito
Arntriciui shad
• L.
rainbow smeu
A.C
A.C
A.C
A.C
A.C
C
A
C
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Genus/ Species^
Common Name
Reference-
Genus/Speciesr - ~"
•^.. ..-^- _...
'Lxth'uuuirlXailiai-
References-
Marine, Seasonal Visitors as Adults
Anchoa hepsetus
Poilachtus virens
Morone saxarilis
Centropristis striata
Stenotomus
chrysops ,
Mugil curema
Ammodytes.
americanuf
Fwtdulus
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The piping plover (Charadrius melodus), listed as threatened; and the least tem (Sterna
antillarum), listed as being of special concern, nest on South Gape Beach and Washbum Island.
The roseate tern (Sterna dougaLli), a species listed as endangered, forages in the water and rests
on the beach proper (WBNERR. 1993; 1995).
E.I.3 Coastal Plain Rivers
Coastal plain rivers also provide an important source of water for upland species and are
prime habitat for fishes, turtles, ducks, and geese. Forests of scrub oak and pitch, pine are
frequently encountered in the surrounding soils, which are mostly consolidated sand dunes. The
largest and cleanest contributor of fresh water to Waquoit Bay is the Quashnet River (also called
the Moonakis River in Falmouth), which had an average streamflow of 391 L/sec (13.S cubic
ft/sec) or 8.9 million gallons per day from 1988 to 1991 (Barlow and Hess, 1993). The Quashnet
originates in a spring-fed cedar swamp at the top of John's Pond. Outflow from Johns Pond to
the Quashnet can be regulated by a gate-controlled spillway. From the pond, the river enters
cranberry bogs, flows east for 0.6 km (0.4 mi) then flows south for 5.6 km (3.5 miles) (Baevsky,
1991). finally emptying into Waquoit Bay.
Besides providing a source of fresh water to Waquoit Bay, the Quids and Quashnet
Rivers provide a relatively rare and shrinking habitat for several anadromous and catadromous
finfish species (Baevsky, 1991). Brown trout (Salmo tnata), brook trout (Safvelinusfontaudis),
alewtfe (Alosa aestivalis), white perch (Morone americana) use these rivers as a conduit for
spawning grounds either within the rivets themselves or within John's Pond (McLamey, 1988;
S.T. Hurley, 1994, Massachusetts Divsion of Fisheries and Wildlife, pen. coram.). American eels
(Anguilla rostrata) use these riven as a conduit for spawning grounds in the open sea. These
species require very specific ranges of certain water quality parameters (temperature, pH,
dissolved oxygen, salinity) which may vary over the stages of egg, larval and juvenile development
(Hunter, 1991). Under the care of the Northeast Chapter of Trout Unlimited, ecological integrity
and stability in die Quashnet have recently improved significantly. The river now hosts a 1.6 km-
(1 mi-) long trout spawning reach 3.5 to 53 km (22 to 33 mi) downstream from the spillway.
The'upper Quashnet River receives constant temperature groundwater discharge through the sand
and gravel bottom (USGS, 1991), which keeps river temperatures moderate, from 10 °C to 17.9
°C (50 °F to 64 °F) in the spawning reach (Baevsky, 1991). Blueback herring, striped bass, and
white sucker (Cata&cmus commersonilaK also commonly found in this stream.
The characteristics of the high volume of ground water inputs into the Quashnet River
significantly influence the water quality parameters of the river. At present, the waters seeping
into the Quashnet ate fairly pristine, with a dissolved oxygen content of 93 to 12.6 mg/L, (well
above die minimum requirements for the most sensitive brook trout),.pH between 6.0 and 6.4
(coo low for the Class B requirements), and a nearly constant temperature of 14 °C (57 °F)
resulting from groundwater seepage (Baevsky, 1991). For example, the temperature remained
between 10 °C and 17.9 °C (50 °F and 64 °F) in the spawning reach during 1988 (Baevsky-.
1.991). In that same year, the temperature entering the river from John's Pond was 263 "C (79
°F). The inputs from ground water are also crucial to mainnwiif»g sufficient volume in the river
for fish to move upstream.
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The good water quality of the Quashnet River also provides habitat for a variety of
macroinvertebrates which serve as a food source for the finfish communities (Pennak, 1989). As
part of Trout Unlimited's restoration project, macroinvertebrate species were reintroduced to the
Quashnet from other freshwater streams. A survey done in 1982-1983 found species representing
the Trichoptera (caddisfly), Diptera(true flies), Lepidoptera (butterflies and moths),
Ephemeroptera (mayflies), and Plecoptera (stoneflies) orders (Wright. 1987). Stoneflies. and tc
some extent mayflies and caddisflies, are good indicators of healthy water quality as they require
fairly high levels of dissolved oxygen.
E.1.4 Freshwater Ponds
Ashumet Pond and Johns Pond are coastal plain kettle hole ponds located within the
Waquoit Bay watershed, north of the bay itself. There are no surface outlets discharging from
Ashumet Pond. Ground water recharge occurs in the upgradient area and the pond recharges the
ground water on the downgradient side of the aquifer. Johns Pond connects to the Quashnet
River by a surface outlet at a gate-controlled spillway. This spillway can draw down die level of
Johns Pond to 1.2 m (4 ft) below it average elevation. Ashumet Pond covers 82 ha (203 acres).
with an average depth of 7 m (23 ft) and maximum of depth'of 20 m (66 ft); Johns Pond covers
131 ha (324 acres), with an average depth of 5.9 m (19 ft) and maximum depth of 19 m (62 ft)
(Duerring and Rojko, 1984a; I984b).
Fish populations including largemouth (Micropterus sabnoides) and smailmouth .
(Micropterus dolomeiui) bass, trout, and brown, bullhead catfish (Ameiurus nebulosus) reside
within Ashumet Pond and similar fishes have been recorded in Johns Pond. Freshwater mussels
are also abundant in the ponds. A high diversity of phytoplankton is present in the.photic zone.
but limited vegetative growth on the shorelines has been documented (HAZWRAP. 1994,1995).
Within the vicinity of the ponds, several species have been designated as having special concern or
threatened status, including the sandplain flax, the marsh hawk; and the grasshopper sparrow.
The upland sandpiper is listed as a state endangered species.
E.1.5 Fresh water Wedands
The freshwater wetlands of the Waquoit Bay watershed covered approximately 83
hectares in 1990 (Appendix F) and support many wetland plant and animal species. Important
freshwater wetlands include the Ashumet and Johns Ponds shorelines. Waterfowl are dependent
upon these wetlands for breeding, foraging and migratory needs. These habitats provide a
valuable refuge for many types of wildlife, including the osprey (Pandion hdtitutus) which forages
for fish hi freshwater areas.. Many upland wildlife species are seasonally dependent on wetlands,
including song and game birds, opossum (Dtdelphis virginiana), raccoon (frocyon lotor lotor),
and white-tailed deer (Odocoiletu virginianus).
EJ, ECOLOGICAL EFFECTS
The wafers of Waquoit Bay and associated freshwater ponds are exhibiting signs of water
quality degradation and the diversity and abundances of key aquatic species have changed, notably
during the last 30 years. In the Bay, increased phytoplankton populations have decreased water
clarity and the amount of light penetrating the water. Extensive mats of macroalgae consisting
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mainly of the species Cladophora vagabunda and Gracilaria tikvahiae, which was unknown in
the bay in 1969 (Curley et al.. 1971), cover most of the bay (Valiela et ai., 1992). The extent of
eeigrass habitat has declined, from approximately 81 ha (200 acres) in 1950 to only 16 ha (40
acres) in 1987 (Costa et al., 1992). EeJgrass is now restricted to fragmented beds near the mouth
of the bay and the tidal inlet near the mouth of the Eel River adjacent to Washburn Island, to the
small salt pond and salt marshes of Washbum Island, and to small patches in Hamblin Pond, Jehu
Pond, and Sage Lot Pond (Figures E-2 and E-3) (Short et al.. 1993). Physical destruction of
eeigrass and sal tmarsh has also occurred.
Water clarity has also been reduced by increased sediment particulates released into the
Bay, rivers, and ponds. Settling of unconsolidated particulates has adversely affected nursery and
spawning habitats for fishes, as well as benthic invertebrate communities.
Alterations in the composition of species dependent on the eeigrass for nursery or adult
habitat have occurred, with declining abundance of commercially important finfish, such as
flounder, pollack, and hate, and shellfish, particularly the scallops. In July 1987,1988, and 1990.
fish kills occurred in Waquoit Bay and the northern beach was covered with thousands of dead
'winter flounder, shrimp, blue crabs, and other estuarine species (Sloan. 1992; EXAvanzo and
Kremer, 1994). Anoxic conditions in the Quashnet could constitute a barrier to sea-run brook
trout (McLamey, 1988). Phytoplankton blooms in Ashumet and Johns Ponds have changed the
color of the water and depleted oxygen levels in' the hypolimnion of the pond; fish kills occurred
in Ashumet Pond in July 1985 and May 1986 (HAZWRAP, 1995). .
Recent changes and reductions in stream flow have affected netting runs and trout streams
(Bariow and Hess, 1993). These species require certain quantities and depths of water; for
example, alewives that must travel to Johns Pond to spawn need sufficient water
depth to traverse the bogs near the pond and years of low water table levels or reduced flow have
limited their success.
E3 SOURCES AND STRESSORS
Seven physical, chemical, and biological stressors in the Waquoit Bay watershed were
•identified during discussions with the risk management team and the public. The sources of
stressors include human activities within and outside of the watershed. Each stressor was
characterized on the basis of its type, mode of action, and general ecological effects that might
result from exposure to the stressor. In addition, information on the intensity, frequency;
duration, timing, and spatial heterogeneity and extent (scale) were reviewed for each stressor in
the watershed, if available. The susceptibility of the ecosystems to the stressors was also
examined.
EJ.1 Sources of Stressors
Anthropogenic stressors in the Waquoit Bay watershed, are the result of changing land use
patterns along the coastal and upland areas (Appendix F). Land use maps produced by the Cape
Cod Commission and by die LMER group identify land use with respect to commercial, cleared
land and recreation, residential, agricultural, forest, wetland, mining, -waste disposal and
transportation. These maps also depict chaneinff land use oatterns with time. For example, in
F-9.76
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_/?
Pond CLy/
u
m
I
' to
$
o
O
o
nl
O
30
O
o
m
Figure E*2. Coastal area of Falmouth and Mushpcc, Massachusetts, showing eelgrass beds
(hutched areas) in Waquoit Bay, neighboring embayments, and Vineyard Sound, summer 1994
(M.Morton, Tetra Tech, Inc.).
-------
4VT 00
41 45
41 30
41 15
41 41)
33
2
o
I
o
o
I
o
o
31
o
o
n!
71 00
70 45
Figure E-3. Martha's Vineyard,, Nantucket, and south coast of Cape Cod, showing eelgrass beds
jh 1994 (heavy lines). Eelgrass beds shown only from Woods Hole 10 Pleasant Day and on the
north coasts of Martha's Vineyard and Naniucket islands (M. Morton, TetraJ^cli, Inc.).
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1950 2% of the watershed was residential; in 1990 20% was considered residential (Sham et al..
1995). Land use in the watershed is primarily residential, particularly along the Childs River
(McDonnell et al., 1994). In 1938.785 houses had been built in the watershed, but more than
8000 residences were counted in the watershed by 1984. Around Waquoit Bay alone the human
population has increased approximately fifteen-fold in the past 50 years, from 400 houses in 1950
to over 4000 houses in 1990 (Sham et al.. 1995). More than 3000 additional single-family homes
could be constructed in the watershed (Waquoit Bay Watershed Citizen Action Committee.
1992).
Cranberry bogs, the major agricultural land use, have declined over the past century: today
there are less than 350 acres of bogs. Cranberry bogs, golf courses and cropland comprise 1.2
percent, 1.2 percent, and 2.0 percent of land use, respectively, in the watershed (Appendix F).
The Massachusetts Military Reservation (MMR) in the northern portion of the watershed (Figure
E-4) is of special concern due to the contaminant plumes emanating from ten separate point
sources; this installation is the closest to an industrial or commercial land use classification in the
watershed (HAZWRAP. 1995).
Although the Quashnet River has been recognized by some as an extremely valuable
resource, development pressure continues to build in the surrounding towns of Mashpee and
Falmouth and with it the search for additional sources of drinking water. To restrict one
proposed housing development, the Commonwealth of Massachusetts purchased 146 ha (361
acres) of land along the river, thereby limiting this housing development to 185 units without river
frontage (Baevsky, 1991). Ashumet and Johns Ponds also face potential susceptibility to
development pressure. The watershed is particularly susceptible to buildup of nutrients and
chemical pollutants because of the porous soils of the watershed and the limited flushing of waters
from the ponds and the Bay (from a few months to over 30 years). Development in the watershed
has also increased human activities in and on the surface waters, particularly in the ponds and bay.
Stressors associated with atmospheric deposition might also contribute to those already present
from the various land and marine uses.
Residential Development. Activities in the watershed associated with residential land
usejthat might add to nutrient-loading within the ecosystem include on-site septic systems;
fertilizer use on lawns, golf courses, and gardens; and housing and road construction with the
attendant increase of impervious surfaces (Valiela and Costa, 1988). Each of the 8000 homes in
the watershed has an on-site wastewater disposal (septic) system that contributes nitrogen to
ground water which travels to Waquoit Bay. Wastewater is a larger contributor of nitrogen to the
estuary man is atmospheric deposition or fertilizers (Valiela et at, 1996). Fertilizer inputs to
Waquoit Bay are primarily from residential lawn applications. Shellfish beds are frequently closed
at the mouth of the Quashnet River to protect consumers from potential exposure to human
pathogens that are not trapped by septic systems or soil and reach the bay. Pesticide applications
on golf courses, cranberry bogs, and lawns add toxic chemicals. Private and municipal well
development alters ground water flow regimes. Housing and road construction also are sources
of sediments as construction uproots vegetation and toads and driveways increase impervious
surf ace cover. Oil hydrocarbons and other chemicals can accumulate on impervious surfaces like
parking lots and roads and be washed off by rain to enter ground and surface waters.
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— —MUNICIPAL BOUNDARY
— — MM BOUNDARY
CAi*» EDWARDS - AIMC
OTIS - ANC
USCG
VTTEflANS AOUIN
USAF
NTS
12-9-S4
IAAH377.DGN
Figure E-4. Location of the Massachusetts Military Reservation. North of Johns and Ashuraet
Ponds (HAZWRAP, 1995).
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Industrial Uses. MMR. composed of Camp Edwards and Otis Air Base, is located on the
upper western'portion of Cape Cod and covers 8903 ha (22,000 acres). Past industrial and
military activities at MMR have mobilized chlorinated solvents and fuel constituents forming
plumes of contaminated ground water. MMR was added to the National Priorities List (NPL) on
November 21, 1989 (HAZWRAP, 1995). Sewage treatment facilities at MMR and increased
runoff from impervious surfaces add nutrients: well development might have altered ground water
flow (Barlow and Hess, 1993). Ashumet Pond is receiving its greatest input of phosphorous from
the MMR sewage treatment plant (STP). If phosphorous levels continue to remain as predicted
over the next ten years, Ashumet Pond will become eutrophic. Freshwater ponds could also be
affected by other contaminants associated with MMR (HAZWRAP, 1995).
Agricultural Activities. Agricultural practices are sources of nutrients via fertilizer
application and runoff from animal wastes. Other agricultural activities that affect the ecosystem
are the addition of pesticides or herbicides, which can be toxic to aquatic life and water-dependent
wildlife, and the construction and use of flow control structures at Johns Pond for irrigating the
cranberry bogs along the Quashnet River, which can alter flow patterns, change the quantities of
surface water in the ponds and streams, and add to sediment-loading. Migration of pesticide and
other chemical constituents from an abandoned cranberry bog in the watershed could also
contribute chemicals to surface, and ground waters (HAZWRAP, 1995).
Aquatic Activities. Water-based activities also are sources of stressors to the estuarine
and freshwater ecosystems (Waquoit Bay Watershed Citizen Action Committee, 1992;
HAZWRAP, 1995; WBNERR, 1995). These activities include recreational boating, which is a
source of nutrients and human pathogens from on-board septic systems and toxic chemicals from
leaching of antifouling paint chemicals from boat hulls and spills of fuel and other discharges from..
marinas; construction of docks and piers using lumber treated 'with heavy metals and other wood
preservatives or antifouling compounds, which can introduce toxic chemicals to the estuary
(Figure E-5); waterway maintenance, including dredging and shoreline modification, which adds
resuspended sediments; shellfishtng in the estuary, which damages eelgrass habitat, resuspends
sediments, and contributes to harvest pressure; recreational fishing in the estuarine, riverine and
pond environments, which contributes to harvest pressure; and swimming in the Bay and Ashumet
and Johns Ponds, which can disrupt benthic communities and resuspend sediments. More than
2100 boats greater than 6.1 m (20 ft) in length are estimated to use the Bay and rivers (Waquoit
Bay Watershed Citizen Action Committee, 1992), with an unknown number of smaller vessels
using the estuary and Ashumet and Johns Ponds.
Activities Outside of the Watershed. Several land and water use activities are not local
or can interact with local sources of stress: Armoring-of the coast outside of the watershed
changes sediment deposition patterns along the barrier beaches of Waquoit Bay. Offshore fishing
depletes the stocks of commercially valuable species such as. winter and summer flounder,
pollack, striped bass and bluefish. Wet and dry atmospheric deposition of nutrients and toxics can
have sources within and outside of the boundaries of the watershed Automobiles, lawn mowers,
.and motor boats generate NOx's locally. These atmospheric gases also originate hi coal-fired
plants hundreds of miles from the watershed. Nitrogen-containing atmospheric deposition adds
nutrients to the watershed (Valiela and Costa, 1988% Other toxic chemicals and metals can be
adsorbed to particulates from coal-fired plants, incinerators, and automobile exhaust fumes,
settling in the watershed. Mercury is a toxic chemical mat also originates outside the watershed
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Dock counts
1993
Waquoft
Bay
Figure E-5. Dock Counts in Waquoit Estuary in 1993. (Data from (L Crawford, WBNERR).
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but is deposited in the watershed where it can be methylated and accumulate in tissues of fishes
and piscivorous wildlife (reviewed in Facemire, 1995; Fitzgerald, 1995; Hurley, 1995: and
Weiner, 1995', HAZWRAP. 1995).
E.3.2 Stressor Characteristics
Altered flow, sediment, physical destruction, nutrients, toxic chemicals, eelgrass disease.
and fisheries harvesting were identified as the major stressors affecting the ecological resources of
Waquoit Bay watershed.
Altered Flow (Riverine). Hydrologic modification is a physical stressor that results in
altered stream flow patterns and reductions in the quantity of fresh water in surface
waters. Anadromous and catadromous finfishes need sufficient water depth to traverse the
shallow Waquoit estuary and streams; sufficient fresh water is needed to sustain certain estuarine
species that require reduced salinities and prevent saltwater incursions in the ground water (Day
et al., 1989; Milham and Howes, .1994). Changes in the hydrology of the Waquoit Bay watershed
can be sporadic, depending on precipitation patterns, especially the number and intensity of
hurricanes or northeasters versus periods of drought, as well as seasonal requirements for
irrigation of cultivated crops. Long-term reductions in ground water occur from municipal wells
that supply drinking water to the residents from the western lens, of the Cape Cod Aquifer.
Around die turn of the century, cranberry bogs were developed along the upper Quashnet
River and water flowing out of Johns Pond was controlled to provide water to the bogs as
needed, particularly in the fall for harvesting .the cranberries. This land use altered the flow
volume, velocity, and path of die river resulting in loss of spawning habitat for anadromous fish
species. Cranberry bop are often flooded in winter to prevent freezing and die water is then
released hi the spring. While the spring release might counteract die effect of groundwater
withdrawals, the harvest flood waters are often released during the time of autumn spawning for
trout (USGS, 1991). An extensive effort by Trout Unlimited and the Massachusetts Department
of Fisheries and Wildlife has restored major sections of the trout habitat, although some species
have not been restored. Alewives and blueback herring that swim to Johns Pond to spawn also
need sufficient water depth to traverse the bogs near die pond. Cranberry cultivation could be
increasing at the headwaters of the Quashnet hi the near future.
In addition, the Quashnet and die ground water that feeds it are currently under pressure
from urban development (Barlow and Hess, 1993). Plans to develop a community drinking water
well could further alter flows and affect the ground water system (Barlow and Hess, 1993),
including thermoregulation of the temperature of spawning beds in the rivers, which protect the
eggs of some fish species. Longitudinal, lateral, and vertical changes in salinity patterns in the
upper bay could have affected the distribution of some estuarine fauna and flora (e.g., Schroeder,
1978; Welsh et al., 1978; Day et aL, 1989). Dredging activity in the channels leading into
Waquoit Bay changes water flow patterns and flushing rates between Waquoit Bay and Eel Pond,
as well as the smaller ponds (Aubrey et aL* 1993). Changes in current patterns can lead to
shoaling near the inlets to the bay, primarily from flood deltas and secondarily from ebb deltas,
that in turn affect current patterns (Geyer and StgnelL 1992; Fitzgerald, 1993).
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Sediment.' Terrigenous and biogenic panicles accumulating in aquatic ecosystems r'rom
land runoff, erosion, and biological productivity are another physical stressor. Sediment can be
easily disturbed by currents, wave action, or organism movements, suspending particles in the
water column. The particle load is referred to as turbidity, which decreases light penetration
through the water, and the fine particuiates can interfere with feeding and respiration in benthic
and pelagic aquatic organisms and feeding in visual predators. Particles can remain in suspension
as long as the velocity of the water is sufficient to counteract gravitational forces. As water
velocity decreases, sediment particles settle, with heavier particles settling first; for example, swift
flowing streams can carry a higher sediment load that is then deposited when the stream empties
into a slower-flowing river or bay. Thus, fine-grained sediments are more likely to remain in
suspension.longer, resulting in increased turbidity. When the particles settle to the bottom,
deposition on surfaces of sedentary plants and animals, as well as the bottom, can cover
organisms that might have a difficult time removing the particles and alter habitat features, for
example, changing gravel bottom to mud (NRC,. 1992).
Changes in sediment loading and deposition in the watershed occur frequently, in concert
with changes in precipitation, surface water volumes, wind* or water-driven current patterns, and
construction or other human activities. Acute changes in sedimentation can occur after
catastrophic natural storms such as hurricanes (Hayes, 1978) and after dredging or construction
activities; chronic increases in sedimentation result as sediments'are resuspeoded by currents in
shallow areas. Swimming and burrowing activities of aquatic organisms can also influence
sediment deposition and resuspension (e.g., Yingst and Rhoads, 1978). Resuspended sediments
can reintroduce adsorbed nutrients and toxics to the water column.
The quantity of sediment entering the surface waters of Waquoit Bay watershed from
runoff and rivejs is unknown. Runoff is not thought to be a problem, since water readily
percolates through the sandy soiL Reductions in streambed permeability might occur if fine-
grained sediments deposit in spawning areas of the rivers (Baevsky, 1991), limiting gas exchange
from the eggs with the surrounding water. Increased turbidity from suspended and resuspended
sediments has reduced light levels needed for photosynthesis by eelgrass in Waquoit Bay,
although eelgrass could grow, slowly, at 10 percent of surface light intensity (Short et at, 1989;
Giesenetal., 1990). Sediment particles also increase the potential stress on eelgrass because
epiphytes growing on eelgrass blades are good depositional surfaces for suspended sediments
(Home et aL, 1994). Suspended sediments might also weight down the eelgrass blades causing
them to sink to die bottom where diey can die from insufficient light or suffocation (Kemp et aL,
1993; Short, 198$).
Protecting the coast from erosion by building of jetties and groins has several effects on
estuarine habitats. Jetties and groins alter regional sandand other sediment transport and
sedimentation patterns (WBNERR, 1995). These alterations can have a negative impact on
barrier beaches, salt marshes, and eelgrass beds, all habjtats for estuarine or water-dependent
wildlife. Shoaling near inlets to the bay has occurred from dredging, also changing sedimentation
patterns (Fitzgerald, 1993). These activities might also adversely-.arTect eelgrass beds in lower
Waquoit Bay.
Loss of eelgrass, in turn, also can change sediment depositional patterns since eelgrass
beds enhance sediment deposition (Short, 1984; 1989). The distribution and abundance of many
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benthic organisms can be adversely affected by sediment deposition. For example, softshells or
steamers grow best in Fine muddy sediments, but they are .more susceptible to predation in these .
habitats (Funderburk et al.. 1991). Siphon-clogging problems might occur in mud substrata which
can offset rapid growth rates in these sediments {Emerson et al.. 1988). Hard clams or quahogs
grow best in sandy sediments, since higher water currents provide more food to these suspension
feeding organisms (Rice and Pechenik. 1992). Juvenile quahogs lack extensible siphons and
attach to sand grains with byssal threads to permit them to feed at the sediment surface. Despite
this affinity for sandy to muddy sand sediments, adult quahogs are found in a variety of sediment
types, with gravely sediments providing protection from predators. The thick shell, lack of shell
gaping, and benthic burrowing limit the predation on these clams. It is not known whether
changes in the composition of the substratum have altered community structure to increase
shellfish predation.
Physical Destruction. Direct and indirect alteration of habitat structure is a physical
stressor that results in changes to the physical, chemical and biological conditions that support
the survival, growth, and reproduction of different species of plants and animals in a community.
In addition to hydroiogic modification, changes in current and flow patterns, and increased
sedimentation, several other mechanisms can alter the estuarine habitat in the Waquoit Bay
watershed, with subsequent effects on the organisms (Day et aL, 1989). These activities occur
sporadically;, the changes in conditions brought about by physical destruction can be short- or
long-term, but restoration of the habitat to its structure and function prior to destruction might be
impossible (NRC 1992).
Shading by docks built from shore- into the estuary, particularly in Great River, a tributary
of Waquoit Bay, decreases light penetration, adversely affecting eelgrass (Burdick and Short.
1995). This is not considered a major stressor on eelgrass or other aquatic lire in Waquoit Bay,
however, since the area covered by docks is small-less than 1 percent of the surface water area in
Waquoit Bay, its tributaries, and ponds (WBNERR, 1995). Mechanical disruption from clam
digging, boat props, and moorings can cut eelgrass blades or uproot eelgrass plants resulting in
death of eelgrass itself. Habitat fragmentation from these activities affects organisms mat reside
in eelgrass meadows. On land, construction of roads near the estuary can stop the landward
progression of salt marshes with deleterious effects on inhabitants.
Nutrients. Nearshore waters worldwide are receiving increased releases of nutrients,
particularly nitrogen, from coastal watersheds (e.g., Nixon et aL. 1986; Valiela et aL, 1990;
USEPA, 1994). Entrophkation, especially nitrogen enrichment in estuarineecosystems and
phosphorus enrichment in freshwater ecosystems, has been implicated as a major cause of
phytoplankton and nuisance macroalgal blooms (Day et aL. 1989; Batiuk et aL. 1992; MALMS,
1992). Inorganic nitrogen and phosphorus, primarily in the form of nitrate and phosphate, are
essential for the growth of photosynthetic algae and plants. La addition to inorganic carbon,
silicon, and other compounds (reviewed in Goldman, 1974, and Day et al., 1989). In the aquatic
environment, nitrogen is converted to various forms through complex biogeochemical cycles that
reduce or oxidize the elements or transform organic compounds to inorganic states, including
decomposition and excretion (of organic forms, ammonium, and phosphate), bacterially-mediated
nitrogen fixation (reduction of inorganic nitrogen to ammonium), nitrification (oxidation of
ammonium to nitrate), and denitrification (conversion of nitrate to'nitrogen gas by anaerobic
processes); Phosphorus is cycled through dissolved inorganic phosphorus, particulate organic
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phosphoms, and dissolved organic phosphorus states involving plants and complexation with
metals in sediments. Plants assimilate nutrients and produce, biomass by various biochemical • •
reactions during photosynthesis and these reactions are driven by the quantities of nutrients
available until they are saturated; usually the concentration of one or more nutritional substances
is less than its saturation level, limiting photosynthesis and plant growth. Day et al. (1989) noted
that aquatic plants have adapted to the average nutrient concentrations to which they have been
exposed.
As noted above, the sources, pathways, and fate of anthropogenic nitrogen are related to
land use patterns and in part to local and regional geology. Much of the nitrogen is believed to
be attenuated during passage through the Waquoit Bay watershed via volatilization, uptake by
flora and fauna, adsorption, and denitrification (see Rhodes et al'., 1985; Nixon and Lee, 1986;
Seitzinger, 1988; Reddy et al., 1989; WBNERR. 1993). The porous, sandy soils of this
. watershed promote rapid percolation of precipitation with the result that there is little run-off
from surface sediments (Strahler, 1968; Valiela et al., 1990; Oldale, 1992). Thus, nitrogen, added
either by precipitation or dry deposition, rapidly enters the ground water and can travel to
Waquoit Bay (Figure E-6). In a like manner, septic system and fertilizer additions of nitrogen and
phosphorus also penetrate the soil and make their way to the ground water and to Waquoit Bay -
(Valiela et at, 1996). Microbial decomposition of biogenic material and direct excretion by
animals into the ponds, rivers, and estuary are biological sources of nutrients. These processes -
interact with chemical processes occurring in the water column and sedunetns related to oxidation
and reduction of the nutrients to increase or decrease the quantities and forms of nutrients
available in the Waquoit Bay watershed (HAZWRAP, 1995).
Ground water concentrations of nitrogen are higher in more developed areas on Cape Cod
than in less developed areas (Figure E-7) (Persky, 1986).. Do the Waquoit Bay complex,
subwatersheds can be identified which have experienced different rates of nutrient loading due to
different patterns of land use. Ground water concentrations of nitrogen are higher in the more
developed than in the less developed subwatersheds (Table E-2) (Valiela et at, 1992; Rudy et al.,
1994). Different ratios of dissolved organic nitrogen (DON) to dissolved inorganic nitrogen
(DIN) were found in the ground water of the Waquoit Bay watershed, with the most urbanized
subwatershed, the Childs River, having a ratio of 1:2, and the least urbanized, Sage Lot Pond,
Table E-2. Nitrogen Levels farGroundwater of the Childs River Sobwafe
to thai of Sage Lot Pond.
shed
Compared
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m
to
oo
Plant accretion (since mid 1800's)
Precipitation
t
Fertilizers
Oenitrification
X
Percolation
Septic systems.
NH4 adsorption
N2l N20
Nitrogen entering
coastal bay
Figure E-6, Inputs and fate of nitrogen (mol N K lO'yr') entering the watershed and traveling toward Buttermilk Bay near Wuijuoii
Bay; Additional sources not shown are precipitation directly onto surface waters and onto impervious surfaces thai aio washed inu>
surface waters. (Reprinted from "Couplings of Watersheds and Coastal Waters: Sources and Consequences o! Nutrient liiuichiucnt in
Waquoit Bay, Massachusetts," by Valielael al., published in Estuaries. December I992, Vol. 15. No. 4, pp. 443-457. wiili
from Estuaries. ©Estuarine Research Federation.)
rn
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*;t
8
9
4O
Building density (nouses
Figure E-7. Nitrate Concentrations in Ground Water Below Areas of Cape Cod Having Different
Densities of Buildings, Based on Data from Persky (1986) (Reprinted from "Couplings of
Watersheds and Coastal Waters: Sources and Consequences of Nutrient Enrichment in Waquoit
Bay, Massachusetts," by Valiela et al, published in Estuaries, December 1992. Vol. 15, No. 4,
pp. 443-457, with permission from Estuaries. ©Estuarine Research Federation.)
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having a iratio of 7:1 (Rudy et al., 1994). DON also appears to be influenced by the presence of
salt marsh, creating anoxic ground water and increasing the accumulation of DON. Ground water
travels at the rate of 13 feet per day in the watershed. Houses built very close to the shore have
the greatest impact on nitrogen loading to the bay. Year-built data and proximity to shore data
show that nearsnore areas were developed first and are the most densely developed (Sham et al..
1995).
Residential septic tanks could also be responsible for the additional input of naturally
occurring nutrients such as phosphorus and nitrogen into both of the freshwater ponds. The
MMR STP plume has been identified as the primary source responsible for increased levels of
phosphorous to the ground water discharging into Ashumet Pond (HAZWRAP, 1995). Since
1936, the disposal of treated sewage from MMR has been accomplished through infiltration beds
to a sand and gravel aquifer, creating a plume of contaminants 914 m (3,000 ft) wide, 23 m (75 ft)
deep, and more than 3353 m (11,000 ft) long, including high levels of sodium, chloride, nitrogen,
detergents, and other sewage-related compounds (LeBlanc, 1984; LeBlanc et al., 1991). Fate and
transport of contaminants in these plumes has proven very difficult to evaluate due to the
influence of the two large kettle hole ponds, Ashumet and Johns Ponds, on ground water flow.
Contaminants appear to be both discharging to the ponds and migrating under the ponds. The
USGS is currently evaluating the current and future impacts of phosphorus on Ashumet Pond; the
concentrations of phosphorus in the hypoliranion are higher in Ashumet Pond than Johns Pond,
but preliminary studies suggest that phosphorus might not be limiting here (Table E-3)
(HAZWRAP, 1995). The Quashnet River and Waquoit Bay are potential future locations for
ground water discharge of MMR plume contaminants in the absence of remediation.
Atmospheric NO3 and SO, deposition are either directly deposited to surface waters or are
transported in terrestrial runoff and drainage into ground water. The latter transport pathways
threaten to lower pH levels hi the Quashnet River and other surface water- or ground water-fed
streams in the watershed because mere is very little natural buffering capacity in the glacial soils.
The pH of the Quashnet is in the range of 6.0 to 6.4, which is not in the optimum range for brown
and brook trout and does not meet the Massachusetts Surface-Water Quality standards of 6.5 to
8.0 for Class B streams (Baevsky,. 1991). The major limitation for assessing the potential
ecological effects of nutrients on the Quashnet River is the paucity of available data.
Conversely, ecological effects of nutrients in the ponds and the bay have been extensively
studied. Phytoplankton blooms have appeared in these ecosystems (HAZWRAP, 1995;
WBNERR, 1995). Increased phytoplankton productivity decreases light penetration, altering the
light regime for submerged aquatic vegetation (Batiuk et al., 1992). Macroalgal matt, consisting
of the fast-growing species Oadophora vagabunda and GracUaria tikvahiae are present in the
shallow bay bottom adjacent to highly developed land areas, particularly the lower Quids and
Quashnet Rivers (Table E4). Epiphytes have grown on eelgrass blades (Valiela et aL, 1992;
Peckol et al., 1994), leading to reductions in the size of eelgrass patches in the bay (Orth and Van
Montfrans, 1984; Costa, 1988;BurkhoideretaL, 1992; Short et al., 1992; Valiela et al., 1992;
Boxhill et al., 1994; Hurlburt et at, 1994). Nutrients might not be the only factors influencing
phytoplankton and macroalgal growth in the ponds and bay, since altered/low ground and surface
water flow, changes in the distribution and abundance of herbivores, and light penetration (which
changes daily and seasonally) could also affect the abundance and distribution of key aquatic flora
(reviewed in Cambridge and McComb, 1984; Cambridge et al., 1986; Day et al., 1989; Necldes et
al., 1993; Boxhill et al., 1994).
E-289
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Table 3. Nutrient loading from the Massachusetts Military Reservation. N + P data extracted from Figures 7.26 through 7.29,
Volume II (HAZWRAP, 1995). Biology data extracted from pages 79-410, Volume I, and Figures 7.24 and 7.41 m volume II
(HAZWRAP, 1995).
/
Site
November 1992
Johns Pond
AshumetPond
April 1993
Johns Pond
Ashumet'Pond
June 1993
JohroPond epdimnkm
Johns pond hypolinuUon
Ashufnet Pond epHimnion
AshumetPond
hypoliinnion
August 1993
Johns Pond epUimnton
Johns pond hypolimnion
Ashumet Pond epl|knnkx»
AshumetPond
hypolimnion
Nutrients
Total DIN
«0-N/L
-60
-40
NH,
^g-N/L
-10
-3
NO,
ng-WL
-SO
-38
SRP
xg-p/i
-0.5
-1
TSP
MQ-P/t
-2.5-6
-7-10.5
Biology (Phytoplanklon)
Number of
cells/ml
-3000
-3000
mg fresh wl./m3
81-622
2447-7939
<-67
-750.
40-70
70-460
-60
-80430
<30
40-730
<20
0-660
<5-67
<6
20-40
40-460
-30
.-30430
<10
10-770
<20
0-860
<10
-750
20-30
<5-120
-50
-50
<20
0-30
0
0-40
~<1
<1
-0.5
0.5-5
-0.6 .
0.5-237
-2.8-5.6
-2
-1.6
1.5-15
-10 ,
10-180
<0.5
0.5-4
o
0-360
2.5-4
4-14.5
<5
5-275
11,000-22.000
20,000-78,000
3500-9200
200-1000
100-5600
100
1100-3800
1100-3800
300-2250
75-45
-25-200
<25
4800-37,000
2000-11,000
4800-35,000
-2000
220-4800
100*300
100-1300
<100
m
o
I
O
O
.1
O
O
D
O
I
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REVIEW DRAFT - 10 May 1996 • DO NOT CITE OR QUOTE
Table E-4. Nitrogen loading to water table, chlorophyll concentrations, and mean (±
standard deviation) biomass of macrophytes in three selected subestuaries of Waquoit Bay.
Adapted from Valiela et al. (1992).
Rnfish and shellfish are at indirect risk from effects of nitrogen loading. Macroalgal mats
provide poorer quality finfish habitat than eelgrass beds for many resident finfish and for young-
of-the-year part-time resident finfish (WBNERR, 1995). Small fish can become trapped in the
tangle of algal filaments (Sloan, 1992). Although photosynthesis by the algae on sunny days
replenishes the oxygen, continuous cloud cover for several days can produce hypoxic or anoxic
conditions under the algal mats and send fishes into shallows where dissolved oxygen levels are
higher (Valiela et al., 1992). Johns Pond is classified as oligotrophic/borderiine mesotrophic;
Ashumet Pond is classified as mesotrophic and the hypolimnion becomes oxygen deficient as a
result of increased decomposition during summer stratification (Ashument Pond Trophic State
and EutrophicatioQ Control Assessment Report, 1987, cited in HAZWRAP, 1995). Fish kills
occurred in Ashumet Pond in July 1985 and May 1986. Mass mortalities of finfish and shellfish
occurred in the upper reaches of Waquoit Bay during July 1987,1988, and 1990. Valiela et al.
(1992) also noted that reduced photosynthetic activity by the macroalgal mats resulted in higher
nutrient concentrations in the water column followed by a bloom of phytoplankton during a July .
1988 prolonged overcast period. Preliminary measured rates of gross phytoplankton production-
and gross ecosystem production in the lower Quashnet River varied with time and decreased in
response to a complex suite of physical factors (Harrison et aL, 1994).
The benthic faunal community is affected by nutrient enrichment in two ways. Fust,
hypoxic and anoxic bottom water resulting from increased algal and microbial respiration,
particularly during cloudy days and nights in summer months, can produce physiological stress
and cause mortalities in benthic community organisms (IXAvanzo and Kremer, 1994). All life
stages of hardshell clams appear to be susceptible to low dissolved oxygen levels in the water,
with growth rates of larvae being reduced below 4 rag/L dissolved oxygen (Funderburk et aL,
1991). Adult clams can tightly close their shells and respire anaerobically in anoxic bottom
sediments in order to withstand these episodic events, but they generally fare better when
dissolved oxygen levels in the overlying water exceed 5 mg/L (Funderburk et al., 1991). Second,
although hard and soft clam growth rates from cleared bottom areas can increase in response to-
higher nutrient inputs and increased phytoplankton production (Chalfoun et aL, 1994; Harrison et
al, .1994), loss of eelgrass beds creates a loss of habitat that provided: shelter, refuge .and a food
source for many fishes and invertebrates (Valiela et aL, 1992). Other changes, in estuarine benthic
E-291
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REVIEW DRAFT - 10 May 1996 • DO NOT CITE OR QUOTE
communities have also resulted from eutrophication (Frithsen, 1991). Invertebrate species
abundance and diversity is lower in areas without eelgrass in Waquoit Bay (Valiela et al,, 1992V
The loss of eelgrass appears to be directly related to the success of scallop larvae. The
bay scallop larvae attach by byssal threads to eeigrass blades and the small juvenile scallops tend
to move up the eelgrass blade to escape benthic predation by crabs, starfish, oyster drills and
wheiks (Pohle et al.. 1991; Garcia-Esquivel and Bricelj, 1993). Byssal thread attachment by
juveniles is reversible and dynamic, allowing the young scallops to keep pace with the growth of
the eelgrass blades, which turn over rapidly during the summer. Rapid growth of juvenile scallops
occurs during this attached phase that can last a couple of months (Pohle et al., 1991). This stage
is followed by descent to the sediments at the base of the blades, at which time an epibenthic
existence without byssal thread attachment occurs. Adult bay scallops can occur in eelgrass beds
or over bare sandy substrate (Garcia-Esquivel .and Bricelj, 1993). Heavy predation by mud crabs
(Dispanopeus sayii), green crabs (Cardnus maenas), spider crabs (Ubinia sp:), and mobile
predators (northern puffer Sphaeroldes- maculatus) and brachyuran crab (Ovalipes ocellatus)
occurs on the small, epibenthic scallops which have shells and are incapable of complete or
provalve closure (Garcia-Esquivel and Bricelj, 1993). Thus, scallop populations tend to be
limited by predation on the attached larvae/small benthic juveniles and water quality affects the
pelagic larvae (MacKenzie, 1989).
Toxic Chemicals. The biota of the watershed could be exposed to potentially toxic and
bioaccumulative chemical contaminants. Toxic substances are materials that are capable of
producing an adverse response in a biological system, altering or impairing its structure or
function or producing death (Rand, 1995). Toxics can affect the induction or inhibition of
enzymes and/or enzyme systems within die cell, in torn altering the functions of these enzymes.
Enzyme dysfunction leads to disruption of metabolic processes including, but not limited to,
phosphorylatiori, uptake, or detoxification reactions, which is reflected in reduced/increased
production of cellular constituents, changes hi cell cycling and replication* and degeneration of
cellular and nuclear membranes. Effects produced by toxic chemicals ate dependent on the
concentration of the chemical and duration of exposure, as well as the type of chemical, its fate
and transport hi the environment, and other factors. Sublethai effects of toxics include changes in
behavior, growth, development, and reproduction of individuals, that ultimately affect the relative
distribution, abundance, and physiological condition of populations within aquatic communities.
Genotypic and pbenotypic factors operating within individuals affect their susceptibility to
different toxicants and ability to roetaboh^ the chemical to prodiH» other osmpcninds erf reduced
or greater toxicity. Some compounds, particularly the more hydrophobic/lipophilic ones, are not
readily broken down in the environment or by organisms and accumulate rathe fatty tissues.
Toxic effects then occur .when the concentrations of compounds are relatively high or the
chemicals are released when fats are metabolized, as during starvation.
The majority of die information concerning toxic chemicals in the Waquoit Bay watershed
is focused on the contribution of contaminated ground water emanating from the MMR
(HAZWRAP, 1995). Johns Fond and Ashumet Pond are located south of MMR and are subject
to potential contaminated ground water flow from the ™»«> industrialized portions of the bass—
including fiightline and fueling areas, and open storm drainage ditches. Water moving down
through soil contaminated by past industrial and military activities at MMR has mobilized
chlorinated solvents and fuel constituents forming plumes of contaminated ground
E-292
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water. Several of these plumes are migrating'within the Waquoit Bay watershed (Figures E-8 and
E-9). Several study sites or areas of concern (AOC) are under investigation north of the ponds
and the plumes could potentially affect both human and ecological receptors. These sites include:
Fire Training Area 2/Landfill-2 (FTA-2/LF-2), the Petroleum Fuel Storage Area (PFSA), and
Storm Drain-5 (SD-5) (HAZWRAP, 1995). For purposes of this investigation,all of the above
described plumes within the Waquoit Bay watershed have been grouped together as the Southeast
Regional Ground Water Operable Unit (SERGOU). SERGOU plumes originate from FTA-2/LF-
2, PFSA and SD-5 and for discussion of the conceptual model. SD-5 will be combined with runoff
from cranberry bogs because of the similar stressors, response pathways and resulting ecological
effects. Areas of concern FTA-2 and LF-2 occupy 20 acres of land used for fire-training exercises
that were conducted on the top of a former industrial/municipal landfill. Compounds disposed of
in the landfill or burned on the fire-training area consist of fuel, waste oils, waste petroleum
distillate solvents and domestic refuse. The PSFA is an active facility that is involved in the
delivery of various types of fuel and was the site of a 2,000 gallon fuel spill in the 1960s (ABB,
1991).
The contaminants from these plumes would affect the northern boundaries of the ponds.
Primary ground water contaminants of concern within SERGOU include chlorinated solvents and
volatile organic compounds such as methanol (Table E-5). Preliminary studies, however,
indicated that levels of volatile and semivolatile organics in surface water and sediments at these
locations hi the ponds were not elevated compared to other sites in the ponds in 1993. Further, it
appeared that some of the detected compounds were introduced as contaminants during
laboratory processing of the samples, e.g., di-n-butylphthalaie and bis(2-ethylhexyi)phthalate
detected in Ashumet Pond in April 1993; memylene chloride, zinc, and chloroform detected in
Johns Pond in April 1993). The greater number of samples collected hi August 1993 in Ashumet
and Johns Ponds did not greatly increase the number of contaminants detected in the surface
water. Neither trichloroethylene nor its metabolite, tetrachloroethylene, nor the common fuel
constitutents of the plumes (e.g., benzene, toluene, and xylene), were detected in fish tissue or
freshwater mussel tissue collected from the pond (HAZWRAP, 1995). The Quashnet River and
Waquoit Bay are potential future sites for MMR ground water discharge effects in the absence of
remediation and therefore the contaminants hi die plumes pose a threat to estuarine receptors.
Little data are available on die quantities and effects of pesticides, polynuclear aromatic
hydrocarbons, polychlorinated compounds, and heavy metals suspected of being present hi the
water, sediments, and biota in the ponds, rivers and streams, wetlands, and estuary. The water
released from tfje.cranberry bogs has contained pesticides and other contaminants that are toxic to
trout and other fish species and die macroinvertebrates on which they feed (MBL Science, 1985).
Pesticides from the MMR SD-5 area are primarily insecticides, rodenticides, and herbicides.
Pesticides widiin the water column can bioconcentrate hi aquatic organisms and accumulate hi
sediments, bioaccomnlate in fish, mussel, or other invertebrate tissues and affect terrestrial wildlife
that prey on these organisms, such as racoons and osprey. Concentrations of PCBs and the
chlorinated pesticides DDD and DDE were higher hi fish from Ashumet Pond man those from
Johns Pond, but all pesticide residues were within die range for comparable reference sites
(HAZWRAP, 1995). Analyses of fish enzymes and freshwater mussel lipids did not indicate
exposure to high concentrations of chemicals; catfish from both ponds exhibited a high incidence
of papUloraas on their jaws and around their mouths and adenocarcmbmas were found in the. •
E-293
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Cn>uudw3ter Phiine
— • Wuctshcd Bouoduy
Military
Reservation
Figure E-8. Groundwater plumes in the Waquoit Bay watershed.
E-294
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REVIEW DRAFT - 10 May 1996 - DO NOT CITE OR QUOTE
SOUTHEASTERN
IMPUIC
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REVIEW DRAFT - 10 May 1996 - DO NOT CITE OR QUOTE
Table E-5. Chemical contaminants in ground water from the Massachusetts Military
Reservation. Data from Monitoring Well Fence 4, Figures 7.1 through 7.6, Volume II,
HAZWRAP (1995). ND m Not detected.
Wells
MW-528 MW-522 MW-519 MW-518 MW-523
VOC 0*9/1)
Tetrachioroetheno
cis-1 .2-Oichloroetriene
1.2-Oichloroethane
Trichtoroethane
/"»U|^«-J*»-^
wntQIUUJim
Total Xytanes
Benzene
EfMM -»»-.—
etnyiDanzarw
1 ,2-Ofchtafoethen* (total)
SVOCfegA.)
Oki-butytpnthaiata
Naphthalene
2-M0thybfiaphthalen«
TPHOigA.)
ND
ND
W
3
ND
NO
1-2
a
0.6
16
t
0.6
D(nolv«d Inorganics* UoA)
Ca~
As
Fa
.Mn
Totw inorganics v^g/M
Cu
K
Fe
As
Mn
11,200
46.0
1630-
2230
33,000
178-788
NO
1
0.6
11.0
7050
1250
75.4-8600
13.0
1450
0,7
0.3
3
2-43
Z
n
0.3
S
11
ND
7.9-19.8
7050*28,200
400
7560-27,200
5.4-19.8
214-380
E-296
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REVIEW DRAFT -10 May 1996 - DO NOT CITE OH QUOTE
Wells
MW-528 MW-522 MW-519 MW-518 MW-523
Cd
Pb
Mg
3.3
3.4
5630
Nutrients (ng/L)
SRF*
TSP*
NH«J
NO,*
26.23-26.39
25.07-29.87
0.19-0.63
572.1-1397
4.19-
22.64
6.13-1387
0.14-0.68
396-1615
23.62-
43.21
21.07-
35.73
0.09-0.10
1931-2085
6.15-21.33
8.8-19.73
0.05-19.81
2.82-2014
1 Values exceeding background levels
*AsP
3AsN
Table E-5. Continued, Monitoring Well Fence 2 (Figures 7.7 through 7.12, Volume II,
HAZWRAP, 1995).
Wells
MW-540 MW-539 MW-543 MW-544
VOC(M9/L)
Chloroform
Trichloroethene
Metnylene Chloride
Tetrachtoroetherw
Trichloroethene
SVOC(MP/L)
TPH (M9/L)
Olssoived Inorganics1 0
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REVIEW DRAFT -10 May 1996 - DO NOT CITE OR QUOTE
Wells
MW-540 MW-539 MW-543 MW-544
Total Inorganics' (pg/L)
Fe
Mn
K
Pb
Zn
Al
Nutrients fcgft.)
SRP«
TSP»
NH«*
NO,»
US
456
1910
5.17-25.58
8.27-26.67
0.41-6.68
40.84-3521
1600
5.2-5.8
105
3.05-23.29
6.67-23.47
0.25-1.98
1551-3260
802
8,76
10.67
1.55
1032
315
1.25-28.19
5.07-31.2
0.36-39.26
14.74-1977
1 Values exceeding background levels
»AsP
3AsN
Table 5. Continued. Monitoring Wefl Fence 5 (Figures 7.13 through 7.18, Volume H,
HAZWRAP, 1995).
««»-M—
trwnv
MW-82S MW-641 MW-621 UW426 UW-524
voc(M9/L)
TricNoroethene
• Chtoroform
1£-DfcntorotttMfle>
SVOCOigA)
Oi^butyphthai*
TPH(M9«.)
Otoeotved UioVM
Inocganlce
K
Fe
Mn
11
1
0.4-0.8
1640
0.7
NO
NO
605
413
NO
NO
—•
0.4
25
05
2
0.44.6
10-59
OJ
NO
0.3
2310
278
1770-3040
'E-298
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REVIEW DRAFT - 10 May 1996 • DO NOT CITE OR QUOTE
Wells
MW-525 MW-541 MW-521 MW-526 MW-524
Ca
Ba
As
Mg
Mn
Total inorganics1
(M9/L)
K
Mn
Fe
Ca
8a
As
Mg
Al
Be
Cr
V
Nutrient*
SRP»
TSP»
NH4S
NO,3
1600
1.9-3158
18.67-35.47
083-2,5fr
158.8-1938
18.300
368
90.7
18,700
2.88-35.37
0.05-33.6
0.94-51.15
240.7-1404
51.37-71.29
48^7-60^7
0.32-0.69
13.25-111.6
72.0
4.2
2260
137-514
68.7
6.5
2.56-15.62
9.87-20
2.027-15.09
662-4248
28.500-
39.500
5030-5740
250-443
5480
254-597
158-14,500
28,600-.
37,100
8.4
4950-8260
11,000
1.4
24.4
26.5
24.44-73.90
29.33-65.87
0.04-24.78
889.4-1622
1 Values exceeding background tavab
2AsP
'AaN
E-299
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REVIEW DRAFT - 10 May 1996 - DO NOT CITE OR QUOTE
Table 6. Chemical contaminants in Ashumet and Johns Ponds (Volume If, HAZWRAP,
1995, Figures 7-33).
Ashumet Pond Aprif 1993
APSW-1 APSW-2 APSW-3 APSW-4
Water concentrations in ugf\
VOCa
SVOCs
Di-n-butylphthaJate
ButyibenzylphthaJate
PEST/PCB*
Metato
Mn
MA
NO
1
NO
34
8660
NO
1
NO
35.7
8780
NO
NO
ND
34.6
8630
NO
1
NO
29.9
8860
Aahunwt Pond August 1993'
APSW-1 APSW-2 APSW-3 APSW-4
VOC»
Acetone
SVOCft
QmntflnhlflmmmLtimmtmt
rentacnioropnenoi
PEST/PC8*
NMato
Ba
Ca
Fa
Pb
Mg
Mn
K
Na
Zn
water concentrations MI MO/I
ND
1
ND
&9-2.1
1920-2900
603-1250
2J
2170-2230
29.6-1770
1170-2060
8560-8920
5.7-12.1
ND
16
ND
ND
2.8-4.3
1930-2540
44
2130-2170
363-344
1170-1230
8370-8770
6.1
NO
NO
NO
3
1885
2195
45.1
1270
9025
ND
ND
ND
2.6
1850
2200
48
125ft
8767
Voi'll, HAZWRAP, Rg. 7-34:
E-300
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- DO NOT QUOTE OR CITE
Table6. Continued. Ashumet Pond sediments, 3rd quarter results. (Volume II,
HAZWRAP,. 1995, Table 7-4).
Ashumet Pond Sediments August 1993
APSD-1 APSD-2 APSD-3 APSD-4 APCB-1 APCB-2
Compounds
VOCs (uo/kg)
Tetra-chloroethane
1 .1 ,2,2, Tetra-chloroethane
1.1, i, Tricntoro-eihane
Toluene
Chlorobenzene
Acetone
2-Butanone (MEK)
Methyl ene.ChkxWe
. Carton Disulfkto
Ethytbenzene
7
280J
20J
100
22
1J
ND
SVOC* fug/kg)
Di-n-butylphthalate
Bis-2-ethylhexylpnthalate
Di*ethylphthalato
TIC (Benzote Acid)
Pentachtoro-pnenol
Phenanthrene
Carbozoto
RuoranthofM
Pyrene
Benzo
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REVIEW DRAFT • 10 May 1996 - DO NOT QUOTE OR CITE
Ashumet Pond Sediments August 1 993
APSD-1 APSD-2 APSD-3 APSD-4 APC8-1 APCB-2
Pestlcida/PCBs (MS/kg)
4.4'-DDT
ND
ND
ND
ND
ND
8.6
Metals fmg/kgt
Al
AS
Ba
Ca
Cu
Cr
Fe
Pb
Mg
Mn
K
Na
V
Zn
1610
2.2
13
333
1660
19.4J
321
66
223
129
43.7
914/793
9.5/8.2
268/198
1250/1172
12.8/8.7
213/223
72.8/88
115/76
56.3/73
3.6/3.0
15.4/19
1110
9.5
118
2.3
2.3
1860
2.7J
258
17*
174
43.8
4.5
10.2
VOCs • Volatile Organic Compound*
SVOCs - Semfeolatile Organic-Compounds
PCBs - Pdychtorinatod Biphenyta
TIC - Tentatively Identified Compound
548
7.9
128
592
6J
109.
56.9
69.4
60.7
12.4
397
1.8
67.4
732
139
57
43.5
45.5
teso
1.1
13.9
1170
12
7.4
4850
22.4J
773
58.2
369
85.5
12.9
ND'Non Detect
• BsonuuM van
IM
Table £•& C^irtfrMmL CTtrmkul cootamiiuuits in Ashtmwt nmf Johns Ponds (Volume n,
HAZWRAP, 1995, Figure 7-36).
Johns Pond Aprt 1993 .
JPSW-1 JPSW-2 JPSW-3 JPSW-4
voc
Mettrylene chksride
Cartaon disutfid*
SVOCs
watar concentrations in ftyi
ND
ND
ND •
9
.
• — —
ND
«.
OJS
ND '
E-302
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REVIEW DRAFT -10 May 1996 - DO NOT QUOTE OR CITE
Johns Pond April 1 993
JPSW-1 JPSW-2 JPSW-3 JPSW-4
Di-n-butyiphthalate
bis(2-chloroethyl) ether
Diefhylphaiate
PEST/PCBs
Metals
Fe
Mn
Na
Zn
NO
48.9
15.2
8910
4.3
2
ND
73.3
22.4
8780
5.5
2
2
2
ND
NO
48.9
13.5
8810
4.8
14.1
8840
4.3
Johns Pond August 1993
JPSW-1 JPSW-2 JPSW-3 JPSW-4
Water concentrations .in vgfl
VOC»
SVOCa
Tributyl phosphate
PEST/PCBs
Metals
Al
As
Ba
Ca
Fe
Mg
Mn
K
Na
Zn
NO
16
NO
6.9-24.7
2840-3350
54.6-1240
2130-2160
36.5-1320
951-1100
83004630
38.9
NO
ND
NO
6.7-8
2840-3270
2150-2160
25.6
969-998
8440 ftflOn
ND
NO
NO
6.9-11.5
2770-2800
24.5-159
2150-2200
29.2-631
995-1100
84104880
NO
NO
NO
20.1
2.1
7
2874
2148
14.75
955
8924
E-303
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REVIEW DRAFT -10 May 1996 - DONOT CITE OR QUOTE
Table 6. Continued; Johns Pond sediments 3rd quarter results. (Volume II, HAZWRAP,
1995, Table 7-5).
Johns Pond Sediments, August 1993
JPSD-1 JPSD-2 JPSD-3 JPSD-4 JPCB-1 JPCB-2
Compounds
VOCs (u
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REVIEW DRAFT - 10 May 1996 - DONOT CITE OR QUOTE
Table 6. Continued. Johns Pond sediments 3rd quarter results. (Volume II, HAZWRAP,
1995, Table 7-5).
VOCs - Volatile Organic Compounds
SVOCs - Semivolatile Organic Compounds
PCBs - Pioychlorinated Bipnenyls
TIC - Tentatively Identified Compound
NO - Non Detect
J - Estimated Value
livers of two catfish from Johns Pond (Table.E-7). The causes of these lesions could be
contaminants, viruses, and/or genetic factors (Harshbarger and Clark, 1990; Baumann, 1992).
Heavy rainfall can result in short-term increases and transport of elevated concentrations of
chemical contaminants. These types of episodic events could cause lethal effects to biota.
Table E-7. Summary of histopathological examinations for brown bullhead catfish from
Ashumet and Johns Ponds, Cape Cod, MA (Volume D, HAZWRAP, 1995, Table 7.17)
Exterior Sores/Growths
Liver Cancer
Macrophage Aggregates
Functional Liver Tissue
47%
0
80% moderate/severe
81%
67*
2 individuals
90% moderate/severe
81%
Another toxic of concern in the watershed is the bioaccumulative and neurotoxic metal mercury.
A concentration of 1.2 mg/kg was detected in one largemouth bass fillet during a study of the
chemical contaminants in Ashumet and Johns Ponds (HAZWRAP, 1995). This concentration
exceeded the U.S. Food and Drag Administration action limit of 1.0 mg/kg to protect human
health. Deposition of mercury into surface waters and accumulation in sediments might produce
sublethal effects in pelagic and benthic aquatic organisms, as well as piscivorous wildlife.
Eelgrass Disease. Pathogens include infectious agents of disease such as viruses, bacteria,
fungi, and protozoa. Disease is any impairment of the vital functions of an organism; it can be
caused by other organisms known as pathogens (biological stressors) or by abiotic factors
(physical and chemical stressors discussed above). Pathogens can be endemic or introduced. The
severity of a disease is influenced by the susceptibility of the host, virulence of the pathogen, and
environmental factors that can affect the ability of the host to resist infection as well as the
proliferation of the pathogen in the environment or in the host. Diseases caused by pathogens
affect commercially important fjnfish and shellfish species in freshwater and estuarine ecosystems,
as well as the organisms on which they depend for food, shelter, and other resources
E-305
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REVIEW DRAFT - 10 May 1996 - DONOT CITE OR QUOTE
(Siridermann. 1990; Couch and Fournie. 1993). Outbreaks of disease can occur sporadically.
although chronic infections can produce siiblethal adverse effects in some individuals of a
population at all times. Biotic diseases can also affect behavior, development, growth.
reproduction, or survival of the population infected by a particular pathogen, as well as indirectly
affecting dependent populations and producing a cascade of effects in an ecosystem.
Although some pathogen-induced diseases of finfishes, shellfishes, and other aquatic organisms
have been reported elsewhere in the Northeast and probably occur in Waquoit Bay watershed and
black-crowned night-herons that feed in the bay have been found with abdominal lesions of
unknown origin (WBNERR, 1993), the .most significant biological stressor recognized in the
watershed is a disease affecting eeigrass. Eelgrass was at one time the dominant submerged
aquatic vegetation in coastal areas of die North Atlantic. In the 1930s the wasting disease, caused
by a slime mold (Labyrinthula) eradicated about 90 percent of the eeigrass meadows on both
sides of the Atlantic. The eeigrass recovered, but then declined again. In the 1980s, another
outbreak of the disease affected eeigrass beds in the United States (Short et al.. 1988). After the
1930s outbreak, many species characteristic of the eeigrass meadows disappeared, including the
gastropod snails Bittium altematun and Miterella, the Atlantic brant (Branta bcrnical hrota), and
the bay scallop (Short et aL, 1988; Short et aL, 1992). Bay scallop larvae and juveniles attach to
eeigrass blades to effectively avoid predators (Pohle et aL, 1991).
The eeigrass wasting disease has been found in a 1989 survey only hi the Hamblin Pond area of'
the Waquoit Bay complex (Short et aL, 1992). The* marine slime mold is adapted to the more
saline waters of die lower reaches of coastal ponds. In the aftermath of die wasting disease, some
eeigrass survived in die less saline parts of estuaries. Today, diese eeigrass beds are threatened by
their proximity to die coasts wim their collateral load of nitrogen and suspended sediments (Short,
1988). The wasting disease might also act synergisticaUy. widi stress from reduced light resulting
in decreased eeigrass growth.
Fisheries Harvesting. Harvesting of finfish and shellfish species by humans is anodw biological
stressor identified hi die Waquoit Bay watershed. Removal of aquatic resources at rates faster
than die organisms can reproduce and replenish die populations results hi reduced abundances and
limitations in distribution, as well as adverse effects on die species that prey on diese
commercially- or recreationally-important species. Qverharvesting has been recognized as serious
tittieat to die stability of freshwater, estuarine, and marine ecosystems (reviewed in Gulland,
.1983). Commercial fisheries can deplete stocks year-round, although fishing pressure is greatest
m summer when weadwr conditions are best
In me Waquoit Bay watershed, most of die finfish harvesting effort occurs offshore, focusing on
winter flounder, summer flounder, tautogs, and Atlantic pollack. Adult winter flounder can be
restricted in tiieir offshore distribution range from certain estuaries, so diat it is not clear dial die
Soutiwm New England (SNE) stock is indeed a distinct subpopulation of fish (biological stock as
opposed to economic stock). The same situation migtitapply to adult tautogs. Summer flounder
are at die northern extension of their range in die SNE area, so that mis species has a lesser
impact in die offshore region, from Waquoit Bay. Quantitative assessments provide evidence of
regional impacts resulting from fishing mortality 'and natural mortality (resulting from habitat
degradation, pollution effects,, eutropbication, meteorological events, and long-term change* in
climate).
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REVIEW DRAFT - 10 May 1996 - OONOT CITE OR QUOTE
Winter flounder and summer flounder are part-time estuarine residents that are important
commercial species in southern New England. Fishing mortality resulted in a 55 percent decrease
in annual survival for summer flounder and a 38 to 42 percent decrease for winter flounder in'
1992 (NMFS/NEFSQCUD, 1992). As a consequence of combined fishing and natural mortality.
the annual survival for summer flounder is 27 percent and that for winter flounder is 24 to 28
percent, which implies that both species suffer from excess harvesting. Thus, regional commercial
and recreational fishing activities play an important role in their distribution and abundance in
Waquoit Bay. The SNE stock biomass levels for summer flounder decreased dramatically from
1985 to 1991, and was dominated in 1991 by fish aged two years and younger (adults are viewed
as two and older). The winter flounder stock in SNE decreased to record low levels between
1989-1991, with a 1991 commercial catch of 4700 metric tons and a recreational catch of 1100
metric tons (NMFS/NEFSC/CUD, 1992).
For the tautog, in Southern New England state waters the maximum estimated fishing mortality
ranges from 0.15 to 0.33 (14 to 28 percent decrease in annual survival). The Massachusetts state
bottom trawl survey for Region 1 (Buzzards Bay and Vineyard Sound) and Region 2 (Nantucket
Sound) has shown a decreased index of abundance from 1982-1986 through 1992, even though a
common indicator of overfishihg, reduction in the average size of the adult tautog caught in
Region i, has not been detected (Caruso, 1993).
Recreational fishing of rainbow trout, brook trout, yellow perch and smallmouth bass within the
freshwater ponds systems is creating a demand on these resources and an increase in local fishing
efforts could reduce these resident finfish populations.
Shellfishing (commercial and recreational) in Waquoit Bay is regulated by the shellfish wardens
in Falmouth and Mashpee; commercial harvest records extend back to 1965 in Falmouth, and
from 1976 through 1987 in Mashpee (Table E-8). Town shellfish landings depend on shellfish
seed set or availability and fishing effort related inversely to shoreside employment opportunities
(MacKenzie, 1989). The quahog landings have been relatively stable during this period. Softshell
landings increased, probably as a consequence of more effort directed toward this shellfishery.
Scallop landings, however, have been mixed due to the short-lived (two years) nature of this
species and variable recruitment. Adult quahogs are susceptible to overfishing because of their
slow growth and variable recruitment; the population in the bay is dominated by commercially
undersized clams (Funderburk et at, 1991). The slow growth rates might also contribute to
increased susceptibility to predation. It takes'approximately two years for juvenile quahogs to
reach a minimum length of two inches in southern. Massachusetts.
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REVIEW DRAFT -10 May 1996 - DONOT CITE OR QUOTE
Table E-8. Shellfish Harvest by Year in Waquoit Bay, From Falmouth Commercial
Harvest Records.
1977
1978
1979
1980
1981
1982
1983
1986
1987
3930
3292
3590
3985
3540
4650
4410
2750
3045
41477
7200
244
596
985
550
3150
2600
232
300
950
1625
1730
1680
1938
1275
1819
54
654
65
100
15
E-308
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REVIEW DRAFT - 10 May 1996 - DONOT CITE OR QUOTE
APPENDIX F
LAiND USE MAPS FOR WAQUOIT BAY WATERSHED
E-309
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Land Use Categories by Classification System
19S1
1971
1980
1985/1990
40 Forest Type*
Agricultural
Agricultural with Walls,
Forest, and Wetland
Agricultural with Fresh
Water Meadow
Abandoned Field
Abandoned Orchard
Orchard
Cranberry Bog
Urban
Fresh Water Meadow
Deep Fresh Water Manh
Shallow Fresh Water
Marsh
Shrub Swamp
Salt Marsh
Fresh Open Water
Salt Open Water
Sand
Tilled/Tillable
Unuse.dTillable
Pasture
Orchard
Abandoned Field
Abandoned Off hf M
Cranberry Bog
Nurseries
Heath
Sand
Power Lines
40 Forest
Dump
Automobile Pumps
Filler Bed
Mining - Sand and Gravel
Mining-Other
Water
7 Fresh Water Wetlands
3 Salt Water Wetlands
4. Water Based Recreation
5 Participation Recreation
S Spectator Recreation
1 Environmental
Recreation
2 Urban Industrial
3 Urban Commercial
10 Urban Residential
S Urban Transportation
2 Urban Open and Public
Agricultural
Pasture
Forest
Open Space
Urban
Water
Cranberry Bog
Oiber
Agricultural
Pasture
Forest
Fresh Water Wetland
Mining
Open Space
Participation Recreation
Spectator Recreation
Water Based Recreation
Multi-Family Residential
High Density Residential
Medium Density
Residential
Low Density Residential
Salt Water Wetlands
Commercial
Industrial
Urban, Open & Public
Urban Transportation
Waste Disposal
Water
Woody Perennial
Cranberry Bog
Golf Course
Marina
Ocean
-------
Cape Cod,
Massachusetts
Pond Recharge Areas
A Snake Pond
B AshumetPond
6 Johns Pond
Drainage Sub-basins
1 Eel Pond
2 Childs River
3 Head of the Bay
4 Quashnet River
5 Hamblin Pond
6 Jehu Pond
7 Sage Lot Pond
Vineyard Sound
S Kaonwtw*
Seal* 1:100.000
-------
Lan
Use Categoric
s
Crop Land
Pasture
Forestland
Fresh Water fell and
Mining
Open Land
Participation Recreation
Spectator Recreatixm
fater Based Recreation
Multi-Family Residential
High Density Residential
Medium Density Residential
Low Densi-ty Residential
Salt let land
Comnercial
Industrial
Urban, Open and Public
Transportation
faste Disposal
fater
foody Perennial
Cranberry Bog
Golf Course
Marina
E-312
-------
Q
-1
1
E-313
-------
1
E-314
-------
c
1 L
0
E-315
-------
i
E-316
-------
4
J_
990
U u \J
E-317
-------
land Use Change over Time (ha!
_anc Use
1951
1971
1980
193;
1990
Acricultural land
Pasrura
Foresc
Fresh Water Weelands
Mining
Open Lands
Outdoor Recreation—Participation
Outdoor Recreation—Spectator
Outdoor Recreation—Water Based
Multi-Family Residential
dense•Residential
Medium Residential
Light- Residential
Salt Hater Wetlands
•Commercial
Industrial
Open and Public Urban Land
Urban .Transportation
Waste Disposal
Open Water
Woody Perennials
Cranberry Bog.
Golf Course
Marina
Total
Total minus open water
358.33
140.53
3717.88
31.19
185.97
90.76
110.21
425.64
321.71
111.11
175.33
23.36
3421.26
74.30
20.09
177.94
0.65
39.70
1.52
122.23
261.83
118.55
4.87
2.54
17.94
580.43
0.92
324.42
25.30
68.91
24.92
0.53
152.07
12.39 '
3201.53
49.56
18.79
191.77
0.22
27.14
286.19
371.56
143.06
1.46
12.58
591.98
324.34
21.58
51.63
25.18
i. ......
28.52
3059.55
80.87
23.50
171. 2S
€..38
3.18
29.43
10.55
34.26
343.30
398.36
129.47
11.84
1.96
203.03
437.01
2.42
354.48
34.18
31.71
26.85
114.13
26.95
2549-91
33.05
27.89
179.52
5.15
3.18
28.05
29.54
43.33
480.40
574.77.
129 . 10
17.22
3.73
22*. 34
440.40
4.07
371.67
14.33
41.77
46.21
2~. 78
5493.39 5493.01 5493.53 5539.58 5549.86
5171.68 5168.59 5169.19 5185.10 5178.19
E-318
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DRAFT Review Draft
DO NOT QUOTE OR CITE June 14,1996
DRAFT PROPOSED GUIDELINES
FOR
ECOLOGICAL RISK ASSESSMENT
NOTICE
THIS DOCUMENT IS A PRELIMINARY DRAFT. It has not been released by the U.S.
Environmental Protection Agency and should not at this stage be construed to represent Agency
policy. Tt i« h»ttig t*mil»tfA fine rnr^mj-nt n«i
Risk Assessment Fonnn
U^. Environmental Protection Agency
Washington, DC
•^-319
-------
DISCLAIMER
This document is an internal draft for review purposes only and does not constitute
Agency policy. Mention of trade names or commercial products does not constitute endorsement
or recommendation for use.
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CONTENTS
Lists of Figures, Tables, and Text Boxes vi
Executive Summary be
1. INTRODUCTION 1
1.1. ECOLOGICAL RISK ASSESSMENT IN A MANAGEMENT CONTEXT 5
1.1.1. Contributions of Ecological Risk Assessment to Environmental
Detiskramaking 5
1.1.2. Risk Management Considerations 6
12. SCOPE AND INTENDED AUDIENCE 7
13. GUIDELINES ORGANIZATION.... 8
2. PLANNING THE RISK ASSESSMENT: DIALOGUE BETWEEN RISK
MANAGERS AND RISK ASSESSORS 11
2.1. ESTABLISHING MANAGEMENT GOALS 13
22. MANAGEMENT DECISIONS ... 15
23. SCOPE AND COMPLEXITY OF THE RISK ASSESSMENT 17
2.4. PLANNING OUTCOME.. 18
3. PROBLEM FORMULATION PHASE 20
3.1. PRODUCTS OF PROBLEM FORMULATION , 20
3.2. ASSESSMENT OF AVAILABLE INFORMATION 22
33. SELECTING ASSESSMENTENDPOINTS,. 25
33.1. Selecting What to Protect 26
33.1.1. Ecological Relevance 27
33.12, Susceptibility to the Stressor 28
33.13. Representation of Management Goals 30
• 33.2. Defining Assessment Endpomts 31
3.4. CONCEPTUAL MODELS 36
3.4.1. RiskHypotbeses 37
3.4.2. Conceptual Model Diagrams 39
3.43. Uncertainly in Conceptual Models 41
3.5. ANALYSISPLAN 42
35.1. Selecting Measures 44
3.5.2. Relating Analysis Plans to Decisions , 46
4. ANALYSIS PHASE 49
4.1. EVALUATING DATA AND MODELS FOR ANALYSIS 52
4.1.1. Strengths and Limitations of Different Types of Data - - 52
4.1.2.- Evaluating Measurement or Modeling Studies 55
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CONTENTS (Continued)
APPENDIX C: CONCEPTUAL MODEL EXAMPLES ,.. C-l
APPENDDCD: ANALYSIS PHASE EXAMPLES D-l
APPENDDCE: CRITERIA FOR DETERMINING ECOLOGICAL ADVERSITY: A
HYPOTHETICAL EXAMPLE E-l
APPENDDCF: AUTHORS, CONTRIBUTORS, AND REVIEWERS F-l
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LIST OF TABLES
Table 4-1. Uncertainty Evaluation in the Analysis Phase 60
LIST OF TEXT BOXES
Text Box 1-1. Related Terminology 1
Text Box 1-2. Flexibility of the Framework Diagram 2
Text Box 1-3. The Iterative Nature of Ecological Risk Assessment 4
Text Box 2-1. Who Are Risk Managers? 11
Text Box 2-2. Who Are Risk Assessors? 12
Text Box 2-3. Questions Addressed by Risk Managers and Risk Assessors 13
Text Box 2-4. The Rote of Interested Parties , 14
Text Box 2-5. Sustainability as a Management Goal 15
Text Box 2-6. Management Goals for Waqnoh Bay 16
Text Box 2-7. Questions to Ask About Scope and Complexity 17
Text Box 3-1. Avoiding Potential Problems Through Problem Formnlation 20
Text Box 3-2, Uncertainly in Problem Formulation » 22
Text Box 3-3. Imtiatmg a Risk Assessment: What's Different When Stressors, Effects, or
Values Drive the Process? 23
Text Box 3-4. Assessing Availabte Information: Questions to Ask Concerning Stressor
Characteristics, Exposure, Ecosystem Characteristics, and Effects 24
Text Box 3-5. Salmon and Hydropower Why Salmon Would Provide the Basis for an
Text Box 3-6. Onrading Adverse Effects: Primary (Direct) and Secondary (Indirect) 28
Text Box 3-7. Sensitivity and Secondary Effects: The Mussd-Fish Connection 30
Text Box 34*. Examples of Management Goals and Assessment Endpoints 33
Text Box 3-9. Common Problems in Selecting Assessment Endpoints .34
Text Box 3-10. What Are Risk Hypotheses and Why. Are They Important? 37
Text Box 3-11. Examples of Risk Hypotheses 38
Text Box 3-12. What Are the Benefits of Developing Conceptual Models? 39
Text Box 3-13. Uncertainty in Problem Formulation 41
Text Box 3-14. Examples ofAssessment Endpoints and Measures 44
Text Box 3-15. Selecting What to Measure 45
Text Box 3-16. How Do Water Quality Criteria Relate to Assessment Endpoints? 46
Text Box 3-17. Data Quality Objectives (DQO)Process 47
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E-323
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1 EXECUTIVE SUMMARY
2
3 The ecological problems feeing environmental scientists and decisionmakers are numerous
4 and varied. Growing concern over potential global climate change, loss of biodiversity, acid
5 precipitation, habitat destruction, and die effects of multiple chemicals on ecological systems has
6 highlighted the need far fl«rihle pmhlenvgnlvmg approaches that can link ecological
7 measurements and data with the decisionmaknig needs of environmental managers. Increasingly,
8 ecological risk assessment is being suggested as a way to address this wide array of ecological
9 problems.
10 Ecological risk asscrenwn* "evafagiex the liir eiihnnd that tthjgrsc ffx>iogical effects gnuy
11 occur or are occurring as a result of exposure to one or nrat stresses
12 pnx^ss for organizing and analyzmg data, infbnnadon,assum
13 me likelihood of adverse ecologk^ effects. Ecological risk assessment provides a critical dement
14 far environmental AietiiMiimlt ing hy giving rklc manager* an appmaeh far enma
15 scientific information along with the other factors mey need to consider (e^, social, legal,
16 political, or economic) in selecting a course of action.
17 To heipinipnwe the qualrtyaiid consistency of E^
18 Risk Assessment Foram mhiated development of these gmdelmes. Previous materials prepared by
19 me Forum to support tmseffonitKludc the 1992 report ^nmewodcfe
20 Assessment" (referred to as the Framework Report) as wdl as numerous case studies and issue
21 papers. These guidelines were written by a Forum work group and have been extensively revised
22 based on conmients from outside peer reviewen as well as Agency sti^
23 guidelines Tetam the FraiMwock Report's bro
24 concepts and modifying others to reflect Agency experiences. EPA intends to follow these
25 guidelines with a series of shorter, more detailed documents mat address specific ecological risk
26 assessment topics. This "booksheiT approach provides the flexibility necessary to keep pace with
27 developments in the rapidly evolving field of ecological risk assessment while allowing time to
28 form consensus, where appropriate, on sdenwpoUcy inferences (defiuilt assumptions) to bridge
29 gaps in knowledge.
DRAFT-DO NOT QUOTE OR CITE ix 6/14/96
E-324
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1 or area! extent and patch size of eelgrass). For a risk assessment to have scientific validity,
2 assessment endpoints must be ecologically relevant to the ecosystem they represent and
3 susceptible to the strcssors of concern. To increase the likelihood that the risk assessment will be
4 used in management decisions, assessment endpoints that represent societal values and
5 management goals are more effective. Assessment endpoints that fulfill these criteria provide the
6 best foundation for an effective risk
7 Potential interactions between agggsy*""1* endpoints and stressors are explored by
8 developing a conceptual modeL Conceptual models link anthropogenic activities with stressors
9 and evaluate intenrlationships between exposure pathways, ecological effects, and ecological
10 receptors. Conceptual models include t™** pr|n£>pn' components! risk hypotheses and a
11 conceptual model diagram.
12 Risk, hypotheses describe predicted relationships between stressor, exposure, and
13 assessment endpoint response, Risk hypotheses are hypotheses in me broad scientific sense; they
14 do not necessarily involve statistical testing of noli and alternative hypotheses or any particular
15 analytical approach. Risk hypotheses may predict the effects of a stressor (e^ a chemical
16 release) or they may postulate what stressors may have caused observed ecological effects; Key
17 risk hypotheses are identified for subsequent evaluation in the Tjyfc
18 A useful vay to express the relationships described by the risk hypotheses is through a
19 eaneepftui ™p4fl dfagrmi. «tf eh if t "ifiti rfpm?f^*«qii of" cmFfrfliil HKKM. Conceptual
20 model mflgfAhi* afg iKgnii teftlg'Tnr enrnrnnm.'^ting important |utKm«y« tn a e\**r anH jvnuti*^
21 way and for identifying major sources of uncertainty. Risk assessors can use both conceptual
22 model diagrams qnd risk hypodieses to idffltify tftP rnoA import
23 that will be evaluated in tile analysis phase. Risk assessors justify what wfll be done as well as
24 what will not be done in the assessment in an analysis plan, the analysis plan also describes the
25 data and measures to be used in me risk assessment and how risks will be characterized.
26 The analysis phase, which follows problem formulation, uidudes two prhwipal activities:
27 characterization of exposure and characterization of ecological effects. The process is flexible,
28 and interaction between the ecological effects and exposure evaluations is recommended. Both
29 activities include an evaluation of available data for scientific credibility and relevance to
DRAFT-DO NOT QUOTE OR CITE xi 6/14/96;
E-325
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I Risk assessors describe risks by evaluating the evidence supporting or refuting the risk
2 estimates) and interpreting the adverse effects on the assessment endpoinL Criteria for
3 evaluating adversity include the nature and intensity of effects, spatial and temporal scales, and the
4 potential for recovery. Confidence in the conclusions of a risk assessment is increased when there
5 is agreement among different lines of evidence of risk.
6 When risk characterization is complete, a report describing the risk assessment can be
7 prepared The report may be relatively brief or extensive depending on the nature and the
8 iwflffpgs avaitefrte *"f tUtg JSftgyyf^n and the infonrMftifln required to support a risk management
9 decision. Report dements may include:
10 • A o^scr^oo of risk assesson^risk manager planning resuhs.
12 • A discussion of fee major data sautes and anarya^
13 • A review of the soessor-response and exposure profiles.
14 • A dfliK'i ijrtKTfi flr nifkft tiff ttig aiHHfymiflHt ^itdpoiiifSt mclttdtng risk CTtnnatCT and adversity
15 evaluations.
16 • AsunimaryofinajorareasofuDcenamryandmearjproacnesusedto
17 • A discussion of science policy judgments or default assumptions used to bridge
18 information gaps, and the basis for these assumptions.
19 To facilitate understanding, risk assessors should chara thy pnMir, thff riffk 'rmmiink*'*™" r**^^ 15 ^^^ «^miBrf hy tailoring
25 information to a particular audience. It is important to clearly describe the ecological resources at
26 risk, their value, and die costs of protecting (and failipgtoprotect) the resources (U.S. EPA,
27 1995d). The degree of cc^oerice m me risk assessment arid the ratkmale for risk n^
28 decisions and options for reducing risk are also important (U.S. EPA, 1995d)l
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E-326
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DRAFT—DO NOT COPY, DISTRIBUTE, OR QUOTE.
APPENDIX F
PRELIMINARY IMPLEMENTATION STATEMENTS
-------
KlflXOM f
DRAFT RISK CHARACTERIZATION XXFLEKBMT&TXOM PLAH
Second Draft
August 29, 1995
9.8. Bnvirouantml Protcotioa Ag«acy
Dallasf Tczaa
F-l
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F-2
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REGION «
DRAFT RISK CHARACTERIZATION IKPLJEMENTATION PLAJT
TABLE OF CONTENTS
I. Introduction. .p. 1
Plan in development
Region 6 Risk Characterization Teas
Draft Plan not reviewed by Region 6 Management
II. Purpose of Document ..,. p. 2
Components of the Regional Plan
III. Background of Risk Characterization.... p. 3
Administrator'.s March 1995 memorandum
Agency Characterization Guidance and Policy
Region 6 risk activities and categories
IV. Relationship of Risk Characterization to Risk
Assessment p. 6
The summarizing step to risk assessment
Not. a reiteration of assessment conclusions
V. criteria for Judging Adequacy of Risk
Characterizations .* p. 7
Administrator's characterization goals:
clarity, transparency,. consistency, reasonable
VI. Ensuring Consistency p. 9
Responsibility of Regional 'Characterization Team
Program documentation
VII. Evaluating Special Circumstances p. 10
Regional examples of Category X and II analyses
VIII.Scope of the Region 6 Implementation Plan. ..- p. 14
IX. Guide for Developing Chemical Specific Risk
Characterizations. p. 15
Summarizing major conclusions
Risk conclusions and comparisons
X. -Statement of Commitment*. ..p. 20
Key elements of the Region 6 Characterization Plan
TABLES
Table 1. List of Region 6 Risk Assessment Activities p. 23
Table 2. Glossary of Acronyms / Region 6 Risk
Related Terms p. 25
ATTACHMENTS
Attachment A. Region 6 Risk Characterization Program Documents
Draft Superfund Risk Characterization Plan (6//9S) .p. Al-1
Draft Risk Characterization} Environmental Justice
Index Methodology (8/95) p. A2-1
F-3
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TABLE OP CONTENTS
Attachment A (continued).
Draft Risk Characterization Implementation Plan UIC
Land Ban Response (8/95) p. A3-1
Attachment B. EPA/Region 6 Memoranda
Administrator's Risk Characterization Program
Memorandum (3/95) p. Bl-1
Regional Risk Characterization Implementation Team
Memorandum from Regional Administrator (5/95)*..p. B2-1
Region 6 Nominee to the Risk Characterization
Implementation Team Memorandum from Regional
Administrator (5/95).. .....p. B3-1
Regional Risk Characterization Implementation Team
Memorandum from Regional Administrator .p. B4-1
Response to Comments on Draft Regional Risk
Characterization Plan. Memorandum from
Risk Team. p. BS-1
Attachment C. EPA Policy and Guidance Documents
March 1995 Policy for Risk characterization at the
U.S. Environmental Protection Agency p. Cl-1
Guidance for Risk Characterization
(February, 1995) p. C2-1
F-4
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REGION « EPA
RISK CHARACTERIZATION IHPLZMEJTPATION PLAN
!• Introduction
Risk characterization is the summarizing step of risk assessment.
The risk characterization integrates information from the
preceding components of the risk assessment: Hazard
Identification, Dose Response, and Exposure Characterization.
Risks can be partially described by the individual components of
a risk assessment, but risk"characterization is a conscious and
deliberate process of bringing all important considerations about
risk into an integrated and complete picture. Even more
importantly, as an integrated picture, the risk characterization
is not simply a reiteration of conclusions of the various
components, but a piece which' focusses on how those components
interact.
The following Region 6 Risk Characterization Implementation Plan
is the second draft of an evolving' set of risk characterization
procedures, policies, and guidelines. This draft Plan has not
been reviewed by Region 6 Management or the Region's legal
counsel. The Plan is a product of risk assessors form the major
Region 6 Programs, risk assessors in all EPA Regions, and a
Headouarters Risk Characterization Core Team.
The plan attempts to address the full scope of risk analyses
performed in Region 6; Regional assessments are defined and
placed into three categories: Screening, Intermediate, and
Baseline (Categories I, II,.. and. Ill respectively). These
categories are used to identify what level of risk
characterization effort, can be performed for each.
Full risk characterizations for Regional products are not
possible at this time for several reasons: 1) Agency guidance is
not available for uncertainty analyses, ecological risk, or cost-
benefit studies.; 2) risk characterizations for Programs involving
permits must be coordinated with National, and State partners; 3)
risk characterization policies have not been developed to address
risk analyses performed by industry facilities, 4) resources are
not available to perform additional, more extensive, risk
characterization procedures and studies.
Although Region 6 recognizes the barriers to full implementation
of Agency risk characterization, the Region is committed to
coordination of risk characterization efforts, ensuring
scientific credibility, and striving to attain the
F-5
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Administrator's goals for clarity, transparency, consistency, and
reasonableness of risk assessment conclusions. Transparency
requires that conclusions drawn from science are identified
separately from policy judgments, and the. use of default values,
methods, and assumptions in the risk assessment are clearly
articulated.
II. Purpose
This Implementation Plan addresses all risk evaluation activities
in Region 6 and provides the Region with guidance for
characterizing risk assessment conclusions. The goal is to
institutionalize a consistent risk characterization process. The
Plan emphasizes the concepts of clarity, transparency,
consistency, and reasonableness. By providing an operational
framework for Region 6 risk characterizations, the Plan expands
on the Agency,'s March 1995 Risk Characterization Policy and it3
accompanying Guidance (Attachments).
The Implementation Plan identifies the kind* of assessments
produced by Region 6 Programs and addresses how the principles
and guidance will be reflected in each, of them. Where a
principle or guidance, point cannot be incorporated, reasons are
given or a plan for filling the gap is provided.
The objective of the Risk Characterization Policy and this
Implementation Plan is to ensure that risk characterizations' .forar
a complete and Coherent picture at; a. level of detail appropriate
•for the decision being supported* Accordingly, greater emphasis
is placed on ensuring clarity, consistency, and reasonableness of
the risk picture and transparency of the decision-making process
than on reformatting or otherwise reiterating the conclusions of
risk assessment components that precede the characterization.
Key elements of the Region 6 Risk Characterization Plan include
the following:
1) An inventory of Regional risk activities with each risk
assessment assigned to one or more categories (TABLE 1).
2) Definitions for three categories of Regional risk
evaluations based on level of effort, cost, statutory
requirements, and uses of the assessment results.
3) formation of a Regional Risk Characterization Team
responsible for coordination. Program consistency, reporting
to Senior Management, and assuring scientific credibility of
risk characterization products.
4) Recognition that full implementation is dependent upon
development of specific technology guidance .documents.
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5) Full implementation is dependent upon technical / statutory
coordination with Headquarters EPA Programs and increased
resources.
6) A schedule for implementing the plan and initiating th«
development of Program specific risk characterization
documents.
7) Recognition that adherence to quality science and rigorous
documentation procedures are the basis for successful risk
characterization in Region 6.
III. Background
In March of 1995, the Administrator issued a policy statement
which requires that risk characterizations be prepared "in a
manner that is clear, transparent, reasonable and consistent with
other risk characterizations of similar scope prepared across
programs in the Agency". The Statement was accompanied by the
Agency guidance jfor Risk Characterj^atj-on. The Administrator's
Risk Characterization memorandum, the Policy and Guidance are in
Attachment A. The guidelines were prepared by the Science Policy
Council in consultation with Regional risk assessors. The
Science Policy council has organized a Risk Characterization
Implementation core Team. The Team is responsible for
coordinating the development of risk characterization plans for
EPA Headquarters and Regions.
Region 6 has participated in the Core Team and Regional risk
assessor's planning conference calls', assisted in development of
a Regional Draft Superfund Risk Characterization Implementation
Plan, and formed a Regional Implementation Team. The Region 6 :
Team is composed of staff risk assessors-from our Water,
Hazardous Waste, Superfund, Air, and Enforcement Divisions* The
Regional -Team is composed of Dr. Jon Rauscher, Dr. Ghassan
Khoury, Blake Atkins, Michael Morton, Young Moo Kim, Maria
Martinez, Mark Hansen, Phil Crocker, Clay Chesriey,- and Dr. Gerald
Carney.
The Regional Team has drafted a List of Region 6 Risk Assessment
Activities (TABLE 1). The Teaa has also assisted in the
formulation of a Program specific risk characterization draft
document. The Draft Superfund Risk Characterization
Implementation Plan was written by Region 2 and reviewed by
Superfund risk assessors representing all ten EPA Regions. The
draft Superfund Plan is Attachment B. The coordination in
writing the Superfund Risk Characterization Plan provided
consistency among Regions for this important Program. The Region
6 Plan directs each Region 6 Program to write a characterization
plan and provides the Superfund. Plan as an example.
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Table 1 provides a listing of various types of Region 6 risk
evaluations divided into three categories relative to data
quality and type, published guidelines, level of effort and cost.
Category I analyses are preliminary or screening risk
evaluations using initial ambient or regulatory data to identify
potential immediate and long-term health impacts from a site or
pollution source. These assessments often include limited or no
sampling data, assumed potential cause and effect: or association,,
evaluation of worst-case exposure scenarios, and a qualitative
uncertainty analysis. Risk managers can utilize this information
to formulate regulatory actions, determine enforcement
prior itization, or to rank various pollution sources.' These
assessments typically cost. less than $50,000 (excluding sample
collection, analysis and corrective action costs) . Level of
effort requirements are usually 1-3 EPA staff or contractor
assistance for 1 to 6 months. Examples of preliminary and.
screening assessments include evaluations for emergency response
activities, enforcement targeting, and risk comparison exercises
using water quality standards.
Category 11 risk assessments are iptefiiaedfrate, analyses and
include- more ambient sampling data* analysis of indirect
exposures, collection of site-specific exposure data, and a
qualitative assessment of uncertainty. The information from
these risk assessments can be used by risk managers to accelerate
.removal actions, to evaluate the effectiveness of remediation
options, water treatment or other regulatory activities.
Typically these assessments cost between $50,000 to $75,000
(excluding sample collection, analysis and corrective action
costs), and require 3 - 7 EPA staff or contractor personnel for 6
to 12 months. - Examples of* intermediate assessments are ranking-
sites for inclusion on the HPL using- the CERCLA Hazard Ranking
System (ERS), Superfund remedial design reviews, and permit
activities in- the HPDES and SDWA Programs.
Category XXX* The baseline or full risk assessment is
exclusively a CERCLA or RCRA program effort in Region 6. They
are analyses of the potential adverse health effects (current or
future) caused by hazardous substances released from a site in
the absence of any actions to control or mitigate these releases.
The baseline risk assessment contributes* to the site
characterization and subsequent development, evaluation and
selection of .appropriate response alternatives.' The results from
the baseline risk assessments provide risk managers with
information to determine if remedial actions are required, modify
remediation goals, -and document the magnitude and causes of the
risks at the site. " These assessments typically involve more
detailed risk characterizations thai} Categories I and IX.
Typically these assessments cost $75,000 or more (excluding
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sample collection, analysis, communication and remediation
costs). Approximately 20 EPA or contract personnel are required
with the effort extending from a 1 to 3 year period. Examples of
Regional baseline risk analyses are RCRA Facility Investigations
(RFI), CERCIA Remedial Investigation/Feasibility Studies (RI/FS),
and RCRA analysis involving incinerators.
It is important to note that these three categories can be a
continuum* The risk assessment activities described under one
category may be found under a different category as the needs for
the assessment and its intended use changes.
The "Guidance for Riafc Characterization* provides general
principles.for characterizing risk. These principles are as
follows:
1) The risk characterization integrates the information from
the hazard identification, dose-response, and exposure
assessments, using a combination of qualitative information,
quantitative information, and information regarding
uncertainties.
2} The risk characterization includes -a discussion of
uncertainty and variability.
3) Well-balanced risk characterizations present risk
conclusions and information regarding the strengths and
limitations of the assessment for other risk assessors, EPA
decision-makers, and the public.
An important early document in the evolution of Risk
Characterization Plans was "Elegants to Consider When Drafting
EPA Risk Characterizationa*. The document was a product of the
Core Team and provided the .following risk characterization
principles;
1) Risk assessments should be transparent, in that the
conclusions drawn from the science are identified separately
from policy judgments, and default values, analytical
methods, and assumptions must be clearly articulated.
2) Risk characterizations should include a summary of the key
issues and conclusions of each of the other components of
the risk assessment, as well as describe the likelihood of
harm. The summary should include a description of the
overall strengths and the limitations (including
uncertainties) of the assessment and conclusions.
3} Risk characterizations should be consistent in general
format,, but recognize the -unique characteristics of each
specific situation.
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4) Risk characterizations should include, at least in a
qualitative sense, a discussion of how a specific risk and
its context compares with other similar risks. This may be
accomplished by comparisons with other chemicals or
situations in which the Agency has decided to act, or with
other situations which the public may be familiar with. The
discussion should highlight the limitations of such
comparisons.
5) Risk characterization is a key component of risk
communication, which is an interactive process involving
exchange of information and expert opinion among
individuals, groups and institutions.
Specific principles for exposure assessment and risk descriptors
are given in the Guidance document. Paraphrased, they are as
follows:
1) Describe the distribution of individual exposures..
2) Describe population exposure.
3) Describe distribution of exposure and risk for subgroups of
the population.
4) Include situation-specific information where appropriate, to
add perspective, for possible future events or regulatory
options*
5) Include an evaluation of the uncertainty in the risk
descriptors.
Clearly it is not always, possible nor even necessary, to include
all risk descriptors for every r4.sk assessment since appropriate
data may not be available or the level of effort required to
obtain the data may not be appropriate for the level 'of decision
being made. An attempt is made in this document, -however, to
address each of the descriptors either by inclusion or by
explanation of why inclusion is not appropriate.
IV. Relationship of Risk Characterization to Risk Assessment
Risk characterization is the summarizing step of risk assessment.
The risk characterization integrates information from the
preceding components of the.risk assessment:'Hazard
Identification, Dose Response, and. Exposure Characterization.
Risks can be partially described by the .individual components of
a risk assessment, but .risk characterization is a .conscious and
deliberate process of bringing all important considerations about
risk into an integrated and complete picture. Even more
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importantly, as an integrated picture, the risk characterization
is not simply a reiteration of conclusions of the various
components, but a piece which focusses on how those components
interact.
V. Criteria for Judging Adequacy of Risk Characterisations
The EPA's commitment to producing risk assessments which include
enhanced, more detailed, and accurate risk characterizations is
dependent upon activities which meet the Administrator's goals of
clarity, transparency, consistency, and reasonableness. Melding
these subjective goals to risk assessment methodologies requires
careful definition of terms. What may be clear-in meaning to one
individual or group may not be so clear to another with different
experiences, training, or biases. Are we to aim for our clarity
and reasonableness toward a technical or non-technical audience?
Understanding that the interests of the Agency is important to
all citizens, it would appear the audience is both. Also assumed
in the qualitative terms transparency and consistency is "full
disclosure" of available information. Again, how transparent and
how consistent? Risk assessors must use the quantitative tools
they have to interpret the Administrator's goals. Setting
measurable criteria for subjective goals will require Program
specific end points. The Groundvater Program will use geological
and hydrological measures. The Drinking.Water Program may use
microbiological measures.
These goals of communicating clearly, having transparent
policies, consistency and reasonable actions can only be realized
if Program methods and logic are accurately documented. This
being accomplished, risk assessment/communication activities can
be clearly chronicled and information more easily accessed by EPA
and others.
1) clarity
Clarity is ultimately determined by understanding. Risk
characterizations should accurately document all data
accessed, the .source and quality of the.data, any bias in
the information, uncertainties, assumptions, and mention of
data not: included or unavailable. .Regulatory data-have a
pre-determined bias. The specificity of the assay used to
measure an ambient concentration or the specific sampling
location for the soil measurement are examples. Although
these are technical factors, they directly affect the
accuracy of the risk analysis. The risk characterization
strengths and limitations should be understood without the
audience having to completely understand the technical
details. Clarity can be accomplished more readily if risk
analysis specifics are easily accessible.
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Region 6 Program risk analyses can identify and assure that
specific bias producing assumptions and default values are
clearly articulated in the Risk Characterization sections of
their analyses. The Region's Risk Characterization Team can
assist each Program in adhering to consistent documentation
approaches and language.
2) Transparency
Transparency is a direct product of clarity and consistency
in risk analysis procedures. The logic.applied to selection
of specific default values should be readily apparent to
reviewers of Region 6 risk assessments. flhere attaining
clarity requires documentation and disclosure of risk
judgements/ transparency requires added statements
explaining the reasoning for assumptions and default values.
(Once I understand what the assessor did, I want to know
why.) with this information the assessment reviewer can
more easily determine the uncertainties and thus the
limitations when presented. The technical reviewer can
calculate risk conclusions based on different logic if
desired. -(Using a different body weight factor for children
or other smaller average weight subpcpulations.)
Accomplishing Regional risk assessment transparency as
defined above can be accomplished by simply defining (and
ultimately justifying) the assumptions and default values
used in risk analyses. This requires bringing these values
out of the dose response;.hazard identification, and
exposure characterization sections of Program risk
assessments. This can be accomplished by referencing and/or
attaching the default documentation used by the Program to
the assessment. Transparency will assist the public in
separating scientific- conclusions from Agency policy
judgements*
3) Consistency ......
Risk methodology consistency within Region 6 Programs, and
between Region 6 Programs, .Headquarter's Offices, State
Agencies, and EPA .contractors will require significant time
to accomplish.' Each EPA Program has developed specific
media terminology, defaults, assumptions, and assessment
guidelines based oa statutory and technical parameters.
Development of risk characterization language for national
permit programs (NPDES, SDWA, UGST) will require extensive
coordination activity among Federal (Headquarters, Regions,
and Laboratories),. State and local governments, and
.industry.
Region- 6 can inventory the risk methodologies, risk guidance
documents employed, decision criteria and logic used for the
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major Programs. This data can be.used to recognize
differences or similarities in report format, interpretation
of regulatory standards, risk language, algorithms, and
application of guidelines. The recognition will enhance
Regional clarity and transparency for risk products.
4) Reasonableness
Reasonableness of conclusions can be determined.if the risk
assessment characterization adheres to the principle of
clarity, transparency, and consistency as described above.
Is it reasonable to. use a 70 Kilogram body weight for a
population of chemical factory workers? Is it reasonable to
not perform an indirect exposure analysis when the source of
pollution is surface water discharge? Proper documentation
of all the risk related data to include information
describing the conservative assumptions and known
uncertainties will ensure more accurate judgements regarding
reasonableness of the analysis.
Procedures taken to document and compare the consistency of
Region 6 risk analyses will afford the Region a means of
comparing one risk to another. If a Superfund analysis
calculates a one in one hundred cancer risk for an exposure
based from water ingestion and the Drinking Water Program
calculates the same exposure at one in ten* thousand, a
reasonableness issue can be raised to both-risk assessors.
VI. Ensuring Consistency
Consistency in .definitions and methods of assessing risk is
fundamental to minimizing confusion, about risk estimates
generated -across the Agency. However, while risk assessments
conducted in Region € share similar goals with risk assessments
prepared by other parts of the Agency, statutory requirements and
regulatory interpretations influence our risk.-assessment .
approaches. The following sections describe areas where Region 6
can use Agency wide definitions, methods, and risk descriptors to
ensure consistency, and areas where such use is constrained.
Reference Doses (RfDs), cancer Potency Factors (Pfs)> Hazard
Indices (HZ),. Health Advisories (HA), Maximum Contaminant Levels
(MCL), Threshold Limit Values (TLVs), Permissible Exposure Limits
(PELS), National Ambient Air Quality Standards (NAAQS), and
Ambient Water Quality Criteria (AWQC) are a few of the many
environmental media standards and risk assessment calculations
used by risk assessors in Region 6. It is common in Region 6 for
risk assessors in our Drinking Water and Superfund Programs to
use an RfD from EPA's Integrated Risk Information System (IRIS).
Therefore., consistency exists among the Programs in using bass
risk assessment values* Inconsistencies occur as each assessor
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applies the value to the specifics of the Hater or Superfund risk
scenarios. Different uncertainty factors or other exposure and
hazard assumptions can be used by assessors. The inconsistency
is compounded when RfDs, Pfs, or MCLs do not exist for a given
compound.
Risk screening and targeting analyses typically use Regionally
derived or national standard toxicity values to infer potential
exposure or health- effects. Screening activities (Category I)
may have the largest range of inconsistent application of risk
values.
The Superfund Hazard Ranking System (HRS) , the National Pollutant
Discharge Elimination System (NPDES) Permit process, and use of
Ambient Water Quality criteria (AWQS)- to determine a screening or
intermediate level risk evaluation all use different algorithms
and exposure factors. The reasons for the. different approaches,
magnitude of the differences, and impacts upon the risk results
can be determined through implementation of the Region 6
characterization plan. The process begins with documentation of
the different analyses, regulatory guidance, and Program
rational*
Region 6 risk assessors from different Programs occasionally meet
to discuss available data and appropriate use of risk values.
The Region 6 Risk Characterization Plan will facilitate this
activity by communicating the Region's inventory of risk
activities, their level -of effort, and analytical processes to
each risk assessor. The Risk Characterization Team can monitor
consistency and be a clearinghouse for Region 6 Program specific
methodologies.
Complete integration, of risk processes is not possible in the
near term. - The Region 6 Plan will immediately begin to identify
and document the different media and statutory characteristics of
each Program 'and to communicate these differences to Regional
risk assessors.
. Evaluatin Secial
The Risk Characterization Policy recognizes that the nature of
the risk characterization will depend upon the information
available, the regulatory application of the risk information,
and the resources (including time) available. Considerations
specific to Region 6 include mandated site specific adherence to
risk assessment guidelines (Superfund Hazard Ranking System,
Remedial Investigation / Feasibility Studies) or analyses which
require coordination between the Region and other State or
Federal offices (FPDES, Air, and RCRA incinerator permits) . Each
have statutory requirements, court-ordered deadlines, or demand
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careful communications with Regional regulatory partners.
Category I and II risk assessment activities in Region 6 require
less than full risk characterization. Category I are screening
evaluations. Such evaluations do not have resources committed to
ambient sampling or extensive literature research. The level of
effort does not justify full characterizations. Category II
analyses are either permit related analyses, Regional guidance
supported by national standards, or risk targeting and
comparative risk studies. These studies usually do not have
level of effort resources to justify full risk: characterizations.
Category II risk evaluation for permit support have the
additional requirement for extensive coordination with our
regulatory partners. There are numerous examples of Category I
and II risk assessment in Region 6. The following are examples
of studies not requiring full risk (Category III)
characterization. Each study does require rigorous documentation
of data sources/ assumptions, data quality, and uncertainties.
1) The Region's Water Quality Management Branch has issued
guidance to our States concerning procedures for development
of water quality standards. The Region's Water Quality
Assessment (WQA) Branch occasionally performs screenings
using water and fish tissue data with State standards. The
Branch may also use national guidance (198$ "gold book*,
Quality Criteria for Water). Cancer risk slop* factors and
RfOs are obtained from IRIS as needed. Although full
characterization is not appropriate for this water analysis,
the Program would be required to document all relative
assumptions, uncertainties, and mathematical manipulations.
The sharing and mixing of Regional, Headquarters, and Stats
guidance and standards will require the Region to address
risk characterization with states
2) . Enforcement Targeting is a screening procedure .using
1990 Census data, Toxic'Release Inventory (TRI) data, chemical
specific information from the Superfund Chemical Data Matrix
document, EPA industry compliance data, and state information
to rank Region 6 industries and federal facilities as. to
potential risk to the surrounding communities. The Region has
performed this screening activity for three years. We share
all information with our State counterparts. Approximately
120 facilities are assessed each year. Environmental justice
(EJ) issues (demographics and proximity to the facility) are
evaluated and each facility is ranked using defined criteria.
The methodology is computerized and developed in coordination
with the Region's environmental justice strategy. A
methodology is written which includes the limitations of the
computer systems used, databases accessed, and assumptions
made by the developers. Separate documents exist' for the
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methodology and computer code. Peer review involves
distribution of the methodology documents inside and outside
of the Region (to .include State agencies and affected
industries).
3) Region 6 Management Division has developed an Environmental
Justice (Computer Assisted Demographic Screening) analysis.
Any Region 6 staff member can obtain population, economic
status, and minority demographic data (1990 Census) for given
communities through the Region's Geographic Information System
EJ methodology. The system requires the requestor to identify
the point which best represents the area and concern, state
the source and .quality of the locational data, and the EPA
program requesting the information. The methodology does not
directly address risk to human health. The system is u'sed
with a risk based analysis (i.e., Enforcement Targeting) to
screen for potential impacts from industry emissions, truck
and rail traffic, proximity to landfills, water treatment
plants, or other regulated facilities.
4) Region 6 Water Supply Program was asked for an opinion on a
pesticide for which there is no MCL or Health Advisory. Water
Supply used the RfD in IRIS and the procedures used by the
OGWDW for developing MCLGs to estimate a safe level in water.
This level was later corroborated with the Health Effects
staff in the office of Ground Water and Drinking water
(OGWDW). This is another screening level risk assessment not
considered to require full (Category III) characterization.
5) In the Public Water Supply .Enforcement Program, risk has been
used to set the national definitions of .significant
noncompliers. The, Regional- enforcement program uses the
national significant noncomplier definition to target
enforcement actions.. In . addition to addressing all
significant noncompliers, the Region also prioritizes certain
acute risks. Targeting according to acute risks and
significant noncompliance assures the highest risk situations
are addressed. This is a Screening Level risk assessment
(Category I).
6) Individual cases of risk are. discussed with water system
owners/operators for determining whether an alternate source
of drinking water should be sought; For example, discussions
with an Indian tribe, which detected high levels of uranium in
drinking water, convinced the tribe to shut down the drinking
water well with the highest levels of uranium and use an
alternate drinking water well with lower detected uranium
levels. As this exercise was part of compliance monitoring,
consider this a screening level risk assessment (Categoryl).
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7} Permitting processes and review in both NPDES and UIC
(Underground Injection Control) use national modeling criteria
which take into account human; health. Hunan health risks are
determined from MCLs and national standards. Consider these
intermediate level risk assessments (Category II).
8) A risk based ranking system for the Underground Storage Tank
(UST) Program is currently implemented by our States. The
analysis (Risk Based Corrective Action - RBCA) examines
contaminants, depth of contamination, population, use of
groundvater and other pathways-exposure criteria. SPA
suggested the methodology and the Region is in a technology
transfer partnership with the States. Questions concerning
risk characterization requirements of State partners for this
shared Program are being addressed by the- Region. The UST
analysis is a Category II activity.
9) The Region 6 Comparative Risk Project required each Program to
submit a "risk assessment* report. Each report discussed
routes of exposure, ambient pollutant concentrations, exposed
populations, and estimates of disease incidence, since the
1990 Region 6 report, Arkansas, .Texas, Houston, and geographic
areas such as the U.S./Mexico border, and the Mississippi
River corridor between Baton Rouge and New Orleans have all
begun some level of comparative risk study. The Arkansas,
Texas, U.S./ Mexico border, and Corridor studies all have EPA
funding. All the studies examine human health, socio-economic
risk, and environmental justice: issues. The Region routinely
participants in the development and review of risk reports
from the different: state, .local government, and academic
analysts. The Region 6 Risk Characterization Plan requires
outside researchers to include risk characterizations
consistent with level' of effort categorization.
An immediate question for Region 6 was what type of risk analysis
(screening, baseline, socio-economic, comparison of a standard to
monitored concentration, qualitative comparative risk study) should
the Regional Risk Characterization implementation Plan address.
The Plan identifies all Regional activities. The identification
process is an on-going activity requiring definitions to separate
risk * assessment from .risk screening, and related analyses. The
three categories were the result of this process.
Examination of the many category I and II risk evaluations
performed in the Region raised several issues. A few of these
question* arer
1) How will risk characterizations address multi-risk projects?
For example, environmental justice requires analyses for human
health, economic, disenfranchisement and other welfare issues?
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2) Rov are enforcement sensitive analyses to be performed? An
. enforcement targeting method for the prioritizing, of chemical
violators is an example. These characterizations will need to
integrate. legal, regulatory, and science issues.
3) Should non-Superfund analyses financed and/or developed with
EPA assistance have risk characterization requirements written
into the grant Statement of WorJc?
4) Should risk characterizations for issuance of EPA Permits be
approved by all parties (Regional permit writer, Headquarters
Office, State Agencies) before incorporation as Regional
policy?
Using the criteria for Category I, II, or III risk, activities vill
determine whether . an assessment requires less-than-full risk
characterization. The Regional. Plan requires full characterization
for category . Ill assessments only. Full characterizations
currently include human health evaluation only. Statistical
uncertainty analyses, ecological and cost-benefit studies are not
required of Category HI risk characterizations. As EPA
guidelines, training, and resources are made available to Region 6,
these evaluation tools and procedures can be implemented.
Communications regarding risk and associated uncertainties are
covered by the Administrator fs Risk Characterization Policy. This
includes communications between scientist*, between scientists and
decision makers, and between Region 6 Programs and the public.
Documents describing components of risk assessments (i.e., hazard
and exposure assessments)..,, even if prepared as separate documents,
will follow the risk characterization policy (striving for clarity,
transparency, c insistency,, and reasonableness) •
Documents related to risk or any of its components which are-
submitted to Region 6 by EPA contractors or other EPA Offices are
expected to follow the Risk Characterization Policy.
Documents from other Agencies or outside sources will conform, to
the Region's Risk Characterization Policy before beincr used for
risk related decisions.
Similarly, Information resource documents such as IRIS documents
which have been produced in the past by SPA but do not follow the
risk characterization- principles will be augmented to meet the
requirements of the risk characterization policy before being used
in making future risk-related conclusions.
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Documents submitted by the public to Region 6 that relate to risk
assessment or any of its components, particularly to support
alternatives to EPA risk assessments, will be evaluated in light of
the Risk Characterization Policy.
Ecological risk assessments are not covered by the Region 6 Risk
Characterization Implementation Plan because detailed guidance are
not available. However, if ecological assessment data is
presented, all ecological risk sections will address the points
discussed in the human health elements document to the extent they
are relevant. Characterizations should address the questions
raised in the Risk Assessment Forum's Framework for Ecological Risk
Assessment.
Assessments of benefits are not included in this Implementation
Plan. Although Region 6 acknowledges the principles of clarity,
transparency of process, consistency, and reasonableness apply also
to analyses of benefits, the Agency has not yet developed guidance
for these types of assessments.
IX. Guide for Developing Chemical-Sped fie Risk Characterizations
The following outline is a guide and formatting aid for developing
risk characterizations for chemical risk assessments. Similar
outlines will be developed for other types of risk
characterizations, including site-specific assessment* and
ecological risk assessments. A common format will assist risk
managers in evaluating and using risk characterization.
The chemical specific risk characterization outline has two parts.
The first part tracks the; risk assessment to bring forward its.
major conclusions. The second part draws all of the information
together to characterize risk. The outline represents the expected
findings for a typical complete chemical assessment for a single
chemical. However, exceptions for the circumstances of individual
assessments exist and should be explained as part of the risk
characterization. For example, particular statutory requirements,
court-ordered deadlines, resource limitations, and other specific
factors may be described to explain why certain- elements are
incomplete.
PART 0KB
SUMMARIZING MAJOR CONCLUSIONS IN RISK CHARACTERIZATION
1) Characterization of Hazard Identification
A. What is the key toxicological study (or studies) that
provides the basis for health concerns?
-How good is the key study?
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—Are the data from laboratory or field studies? In
single species or multiple species?
—If the hazard is carcinogenic, comment on issues such as:
observation of single or multiple tumor sites?
occurrence of benign or malignant tumors; certain
tumor types not linked to. carcinogenicity; use of the
maximum tolerated dose (MTD) .
—If the hazard is other than carcinogenic, what endpoints
vere observed, and what is the basis for the critical
effect?
—Describe other studies that support this finding.
—Discuss any valid studies which conflict with this finding.
B. Besides the health effect observed in the key study, are
there other health endpoints of concern?
-What are the significant data gaps?
C. Discuss available epidemiological or clinical data. For
epidemiological studies:
— What types of studies were used, i.e., ecologic, case-
control, retrospective cohort?
— Describe the degree to which exposures vere adequately
described.
— Describe, the degree to which confounding factors were
adequately accounted for,
— Describe the degree to which other causal factors were
D. Row much is known about fcojt (through what biological
mechanism) the chemical produces adverse effects?
— Discuss relevant studies of mechanisms of action or
metabolism.
— Does this information aid in the interpretation of the
toxicity data?
— What are the implications for potential health effects?
B. Comment on any non-positive data in animals or people,
and whether these data were' considered in the hazard
.identification.
F. If adverse health affects have been observed in wildlife
species, characterize such effects by discussing the
relevant issues as in A through B above.
6. summarize the hazard identification and discuss the
significance of each of he following:
— confidence in conclusions;
— alternative conclusions that are also supported by the
data;
— significant data gaps; and
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— highlights of major assumptions.
2) Characterization of Dose-Response
A. What data were used to develop the dose-response curve?
Would the result have been significantly different if
based on a different data set?
— If animal data were used:
— which species were used? most sensitive, average of
all species, or other?
— were any studies excluded? why?
— If epidemiological data were used:
— Which studies were used? only positive studies, all
studies, or some other combination?
— Were any studies excluded? why?
— Was a meta-analysis performed to combine the
epidemiological studies? what approach-was used?
were studies excluded? why?
B. What'model was used to develop the dose-response curve?
What rational* supports this choice? Is chemical-
specific information available to support this
approach?
— For non-carcinogenic hazards:
~ How was the RfD/RfC (or the acceptable range)
calculated?
— What assumptions or uncertainty factors were used?
— What is the.confidence in. the estimates?
— For carcinogenic hazards:
— What dose-response model was used?. LMS or other
linear-at-low-dose model, a biologically-based model
based on metabolism data, or data about possible
mechanisms- of action?
— What is the basis for the selection of the particular
dose-response model used? Are there other models
that could have been used with equal plausibility and
scientific validity? What is the basis for selection
of the model used in: this instance?
C. Discuss the route, and level of exposure observed, as
compared to expected human exposures.
- Are the available data from the same route of exposure as
the expected human exposures? If not, are
pharmacokinetic data available to extrapolate across
route of exposure?
— How far does one need to extrapolate from the observed
data to environmental exposures (one to two orders of
magnitude? multiple orders of magnitude)? What is the
impact of such an extrapolation?
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D. If adverse health affects have been observed in wildlife
species; characterize dose-response information using the
process outlined in A-C.
3) Characterization of Exposure
A. What are the most significant sources of environmental
exposure?
— Are there data on sources of exposure from different
media? What is the relative contribution of
different sources of exposure?
— What are the most significant environmental pathways
for exposure?
B. Describe the populations that were assessed, including as
the general population, highly exposed groups, and highly
susceptible groups.
C. Describe the basis for the exposure assessment, including
any monitoring, modeling, or other analyses of exposure
distributions such as Monte-Carlo or krieging.
D. What are the key descriptors of exposure?
— Describe the (range of) exposures to: "average*
individuals, 'high end* individuals, general
population, high exposure group(s), children,
susceptible populations.
— How. was the central tendency estimate developed? What
factors and/or methods were used in developing this
estimate?
— Hoy was the high~end estimate developed?
— Is there information on highly-exposed subgroups? Who
are. they? -What are their levels of exposure? - How are
they accounted for in the assessment?
E. Is there reason to be concerned about cumulative or
multiple exposures because of ethnic, racial, o*
socioeconomic reasons?
F. If adverse health affects have been observed in wildlife
species, characterize 'wildlife exposure by discussing
the relevant issues as in A through E above.
G. Summarize exposure conclusions and discuss the following:
— results of different approaches, i.e. modeling,
monitoring, probability distributions;
— limitations of each, and the ranae of most: reasonable
values; and
— confidence in the results obtained, and the limitations
to the results.
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PART
RISK CONCLUSIONS AND COMPARISONS
4) Risk Conclusions
A. What is the overall picture of risk, based on the hazard
identification, dose-response and exposure
characterizations?
B. What are the major conclusions and strengths of the
assessment in each of the three main analyses (i.e.,
hazard identification, dose-response, and exposure
assessment) ?
C. What are the major limitations and uncertainties in the
three main analyses?
D. What are the science policy options in each of the three
major analyses?
— What are the alternative approaches evaluated?
— What are the reasons for the choices made?
5) Risk Context
A. What are the qualitative characteristics of the hazard
(e.g., voluntary vs. involuntary, technological vs.
natural, etc.)? Comment on .findings, if any, from studies
of risk perception that relate to this hazard or similar
hazards.
B. What are the alternatives, to this hazard? How do the
risks compare?
C. How does, this risk compare to other risks?
- How does this risk compare to other risks in this
regulatory program, or other similar risks that the EPA
has. made decisions .about?
- Where appropriate, can this risk be compared with past.
Agency decisions, . decisions by .other federal or state
agencies, or common risks with which people may be
familiar?
- Describe the limitations of making these comparisons.
D. Comment on significant community concerns which
influence public perception of risk?
6) Existing Risk Information
Comment on other risk assessments that have been done on this
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chemical by EPA, other federal agencies, or other
organizations. Are there significantly different conclusions
that merit discussion?
7) other Information
Is there other information that would be useful to the risk
manager or the public in this situation that, has not been
described above?
X*. statement of
Through this Implementation Plan Region 6 intends to ensure that
risk characterizations produced by and for the Region will be
substantially consistent with Agency guidance and policy on risk
characterization, recognizing limitations in time and resources*
The plan will be updated as necessary.
The following is a summary of Key Elements contained in the
Region 6 Risk Characterization Implementation Plan.
1) The Plan addresses all risk evaluation activities providing
general guidance for characterizing, risk assessment
conclusions. The goal is to institutionalize a consistent
risk characterization process in Region 6.
2) The Plan emphasizes the concepts of clarity, consistency, and
reasonableness as stated by the Administrator. Region 6 will
participate in all EPA planned roundtables and workshops to
the. extent possible.
3) The Plan is consistent, in general format and purpose with
other Regions, and Headquarters Programs.
4) The Plan recognizes that full implementation is dependent
upon technical and statutory coordination with Headquarters
Programs. This coordination will be the responsibility of
each Region 6 Program. Full implementation will also require
increased, resources.
5) The Plan recognizes that full implementation is dependent
upon development of specific technology and related guidance
(i.e., statistical tools, ecological evaluation,, cost benefit
analysis, guidance for uncertainty analysis) and Program
specific characterization plans serving as S.O.P.'s.
6) The Plan identifies three risk analysis categories performed
in Region 6. Each category, is defined by specific criteria.
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7) The Plan presents an inventory of Regional risk activities
with each assigned to one or more categories.- A Regional
Risk Characterization Team will maintain a listing of the
Region's various Program assessments, .methods, procedures,
and use of standards.
8) The Plan defines Category III risk analyses as CERCLA and
RCRA baseline assessments.
9) The Plan considers Category II j. analyses as Regional
standards because they have more published guidance,
established EPA policy, and resource commitments.
10) The Plan discusses to what degree specific risk
characterization activities can be accomplished within each
Category.
11) The Plan estimates .the time required to implement specific
risk characterization activities within each category*
12) The Plan suggests an organization structure and Program
policy development plan to ensure consistency of
characterization content for each Regional Program.
13) The Plan provides for a Regional Risk Committee to be formed
providing a forum for risk assessors and managers to monitor
and maintain consistency of .Regional risk products.
14) The Plan requires risk characterization products to be
included in the deliverables for Jteojionally funded risk
assessments.
15) The plan emphasize* the adherence to quality science, .
documentation procedures, and Program institutionalization
of risk characterization*
16) Category I (Screening) assessments should implement the
Regional Risk Characterization immediately.
17) Category X assessments completed after the Regional Risk
Characterization Policy is approved should include
characterization sections to their risk methodology and
summary documents.
18) Category II assessments are to begin coordination activities
with related Region 6" Programs, Headquarters Programs and
Offices, and State partners to determine the feasibility of
including risk characterization sections to their
assessments.
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19) Category III assessments art to consolidate and enhance
risk characterization data and language into a specific
section for methodology and summary documents.
20) Progi
techi
Regie
implf
21) The Category III Programs will develop a five year plan for
Risk characterization implementation.
22) The Region 6 Risk Analysis Team will be accountable for:
- communication, of Regional risk activities
- coordination of cross-Program risk activities in the
Region
- reporting cross-Program activities to Senior Staff
- establishing Program consistency in risk
characterizations
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TABLE 1
List or Region * Risk Assessment Activities
Category Is Screening
Category lit Intermediate
Category Ills Baseline
G8BCL&
CBBCIJk
Time Critical Removals
Engineering Evaluation/
cost Analysis (EE/CA)
RCRA
Multi-media Enforcement
Targeting
8DWA
Risk comparisons using
MCL data
UIC risk comparisons
Hazard Ranking System (HRS)
Interim Record of Decision
Remedial Designs
AVPCOC
Underground Storage Tanks (UST)
RBCA (EPA/state partnership)
Indirect Combustion Analysis
8DWA
EPA HQ risk analyses with
promulgated standards
UIC permits
CBRCLA
Remedial Investigation/
Feasibility Study (RI/FS)
Record of Decision (ROD)
Incineration (Comprehensive
Indirect Exposure Assessment)
(CIERA)
RCRA
Facility Investigation/
Corrective Measures (RFI/CHS)
Incinerators/Boilers
(CIERA)
SOW*
EPA HQ risk analyses with
promulgated standards
CIA CWA
Risk screening of ambient Fish tissue risk analysis using
water using water quality IRIS or guidance values
standards/criteria HPDES permit review/development!
Hater permits (404,305)
Pesticides
Risk comparisons using
HA data
Pesticides
CWA
Risk assessment for a given
subpopulation using
extensive fish tissue
and/or other data with
appropriate assumptions
Pesticides
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TABLB is List of Regiott • Bisk Assessment Activities (continued)
Category I: Screening
Category II: Intermediate
Category III: Baseline
CAA
Risk comparisons using air
quality Btandards/IRXS
MBPa/BXS
CAA
SIPs
Mew-Source Reviews
Mr permits
MBPA/BXS
CAB
MBPA/BXS
Regional Initiatives
U.8 Mexico
Modeling applications
Lower Mississippi River
Corridor
Regional Initiatives
U.S. Mexico
Model development/application
Lower Mississippi River
Corridor
Regional initiatives
.special Projects
Comparative Risk
(Program specific)
Environmental Justice
(Site specific)
Multi-Media Enforcement
Targeting
Special Projects
Comparative.Risk*
(Regional study)
Environmental Justice
(Regional/Program study)
Special Projects
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TABLE 2
Glossary of Acronyaa / Roglon 6 Risk Related Texas
Aix Quality Standards - Criteria Pollutants and National Ambient Air Quality
AL/PCQC (Action Level/Preliminary Chemical of Concern)
AWQC (Ambient Water Quality Criteria)
Boilers - Furnaces/incinerators producing steam for industrial use
CAA (Clean Air Act) -
Comparative Risk * Regional and State analysis which rank environmental risks as to
potential for. adverse impacts to human health* the ecology, economy, and public welfare.
CWA (clean Hater Act)
CERCLA (Comprehensive Environmental Resource*/ Compensation and Liability Act) - Superfund
CMS/SB (Corrective Measure Study/Statement of Basis) - RCRA
CIERA (Comprehensive Indirect Exposure Risk Analysis) - RCRA
EIS (Environmental Impact Statements) - NEPA
EJ (Environmental Justice) - Risk projects which compare demographic data (population,
.race, and household income) for. specific communities iri Region 6.
EE/CA (Engineering Evaluation / Cost Analysis) - CERCLA
HA (Health Advisory) - SDWA, Drinking water standard
HRS (Hazard Ranking System) • CERCLA,. algorithm used to rank sites for possible placement
on the National Priority List-for Superfund.
Incinerators - A furnace for burning wastes under controlled conditions.
IRIS (Integrated Risk Information System) -
Lower Mississippi River Corridor - An area representing the southern one-half of
Louisiana. The corridor defines the river from Baton Rouge, LA to New Orleans.
MCLs (Maximum Contaminant Level) - SDWA
MCLQs (Maximum Contaminant Level Goals) - SDWA
Model Development. - Risk algorithms relating hazard, exposure, emissions, or other risk
factors. Computer model development is often time consuming requiring peer review,
computer specialists, extensive QA, documentation of data sources.
Modeling Applications - Use of risk algorithms to relate hajzard, exposure, emissions, or
other risk factors.
Multi-Media Enforcement Targeting - Evaluations of Region 6J industrial facilities for
enforcement prioritization. Census demographic data and TRI chemical emissions
information is used to estimate potential risk.
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TABLE 21 Glossary of Acronyms/Risk Related Texas (continued)
MTD (Maximum Total Dose) -
NAAQS (National Ambient Air Quality Standards) - Clean Air Act
NEPA (National Environmental Policy Act) Applies to all Federal Agencies
NESHAPS (National Emissions Standards for Hazardous Air pollutants) - CAA
NPDBS (National Pollutant Discharge Elimination System) - CWA
NPL (National Priority List) Sites meeting hazard ranking criteria (HRS) for listing as
Super fund.sites.
OGWDW (Office of Ground Water and prinking water)
PCBs (Polychlorinated Biphenyla) - EPA Program established to regulate disposal and
1 storage of.PCB chemicals.
PELS (Permissible Exposure Levels) - OSHA standards for air pollutant concentrations in
industrial environments.
Pfs (Potency Factors) - Cancer potency judgements found in IRIS
POHC (Principle Organic Hazardous constituent)
QA (Quality Assurance)
RBCA (Risk Based Corrective Action) ••* Underground Storage Tank risk screening activity.
71 EPA and State environmental agencies are in partnership! in implementation and use of
o this ranking system.
ROD (Record of Decision) Public document describing chosen remediation alternative (s)
for a Superfund site. Document includes risk assessment conclusions and data.
RCRA .(Resource Conservation and Recovery Act) - Regulations addressing the classification,
transport, disposal, and documentation retirements for solid wastes.
RfC (Reference Concentration) -
RfD (Reference Dose) - An estimate of a daily exposure to tjhe human population that is
likely to'be without appreciable risk.
RFI (RCRA Facility Investigations) -
RI/FS (Remedial Investigation / Feasibility Study) - CERCLA
Regional Initiatives • Geographic or pollution source specific risk projects specific to
Region 6 (i.e., U.S./Mexico border, Louisiana Corridor, Petro-Chemical 'Industry).
Risk Comparisons • a risk evaluation activity which uses promulgated standards (i.e. MCLs,
Rfds, HA, PELs) to judge the potential risk from a given site or pollution source.
SDWA (Safe Drinking Hater Act) -
SIPs (State Implementation Plans) - CAA
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TABLE 21 Olossacy of Acronyas/Risk Related Texas (continued)
Special Projects •> Risk analysis activities which are generally cross-media in scope and
geographically specific.
TLVs (Threshold Limit Values)
Time Critical Removal - CERCIA
UIC (Underground Injection Control)
UST (Underground Storage Tanks)
27
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DJULFT
RISK CHMiaCTERIZlffXOV ODIDBLIHBI
TOR
TEB OFFXCB Of SOLID «*8YB
U»S.
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TABLE OF COHTEHTS
I. Purpose , 1
II. Background ................ .2
III. Legal Effect.. 4
IV. Scope ............. * ...... 4
V. Relationship of risk characterization
to risk assessment and risk communication . 7
VI. Criteria for judging adequacy of risk characterizations . 8
A. Clarity ....... 8
B. Transparency .....,«..»..... 9
C. Reasonableness • •• • 10
VIZ., Ensuring consistency . . . . . • . 10
VIII.Evaluating Office-specific circumstances ........ 12
IX. Points to consider when preparing risk characterizations
and criteria for evaluating.compliance with the Risk
Characterization Policy .......... . .... . . . . 13
A. Summary, of and confidence in .the major risk conclusions
. . . ... . . ;, . . ... . . . . . . . ...;. 14
B; Summary of key issue* 15.
C. Methods used 16
0. Summary of the overall strengths and. uncertainties
of the risk assessment . . . . .- 17.
B. Put this risk assessment in context with
other similar risks . ............... 19
F. Other information . . . . : 20
6. Mechanism* to evaluate risk characterization ... 21
X. statement-of Commitment 22
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X.
This Risk Characterization Implementation Guideline provides
the operational framework within which all risk characterizations
in the Office of Solid Waste (OSW) are developed. The Guidelines
expand on the March 1995 Risk Characterization Policy and its
accompanying Guidance by providing OSW-specif ic factors which
affect the implementation of the general policy.
The Implementation Guidelines identify the kinds of
assessments produced by OSW which are covered by the Risk
Characterization Policy, and addresses how the principles and
guidance will be reflected in each of them. Where significant
principle or guidance points cannot be incorporated, these
guidelines call on producers of risk characterizations to provide,
reasons for such gaps.
The objective of the Risk Characterization Policy and this
Implementation Guidelines document is to ensure that risk
characterizations produced by this Program form a coherent
picture at a level of detail appropriate, for the decision being
supported. Accordingly, greater emphasis is placed on ensuring
clarity, consistency, and reasonableness of the risk picture and
transparency of the risk assessment process as an input to the
decision-making process than on reformatting or otherwise
reiterating the conclusions of risk assessment components that
precede the characterization.
EPA is developing policies and procedures for several key
issues that cut across the Agency (e.g., uncertainty analysis,
updating IRIS and supplementing IRIS with risk characterization
language in the interim, etc.) . As they are developed they will
become part of OSW' s policy and update this document.
II*
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In March 1995, the Administrator issued a policy statement
requiring that risk characterizations be prepared "in a manner
that is clear, transparent, reasonable and consistent with other
risk characterizations, of similar scope prepared across programs
i
in the Agency."
The "Guidance for Risk Characterization", which accompanies
the Policy Statement, provides general principles for
characterizing risk. These principles are as follows.
l. The risk characterization integrate* the
information from the hazard identification, dose-
response, and exposure assessments, using a
combination of qualitative information-,
quantitative information, and information about
uncertainties.
2. The risk characterization-includes a discussion of
uncertainty and variability.
3. Well-balanced risk characterizations present risk
conclusions and information regarding the
strengths and limitations of the assessment at the
level appropriate for the risk assessment.
Also identified in the "Policy for Risk Characterization" are the
following key aspects-of risk characterizations:
1. Risk assessments should be transparent, in that the
conclusions drawn from the science are identified
separately from policy judgments, and the use of
default values or methods and the use of assumptions in
the risk assessment are clearly articulated.
2. Risk characterizations should include a summary of the
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key issue* and conclusions of each of the other
components of the risk assessment/ as well as describe
the likelihood of harm. The summary should include a
description of the overall strengths and limitations
(including uncertainties) of the assessment and
conclusions.
3. Risk characterizations should be consistent in general
format, but recognize the unique characteristics of
each specific situation.
4. Risk, characterizations should include, at least in a
qualitative sense, a discussion of how a specific.risk
and its context compare with other similar risks. This
may be accomplished by comparisons with other chemicals
or situations in. which the Agency has decided to act,
or with other situations familiar to the public. The
discussion should highlight'the limitations of such
comparisons.
5. Risk characterization iar a key component of risk
communication, which is an interactive process
involving exchange of. information and expert opinion
among individuals, groups and-institutions.
Risk assessments .conducted by OSW require different levels
of effort. They should be viewed as. a continuum, because more
than one level of risk assessment effort may be employed for many
osw actions and activities. Risk assessment activities conducted
to support one level of effort may lead to a different level of
effort as the requirements for the assessment and its intended
uses change. The amount of time, effort and level of detail
devoted to risk characterization in OSW should vary according the
nature and magnitude of the risk assessment.
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Representative assessments done in OSW, including the scope
of the assessments and the level of detail, are described below:
a
1. Baseline Risk Assessments for Hazardous Waste .Listing
Determinations. Multimedia assessments to determine
whether certain specified wastes should be listed as
hazardous. Assessments range from conservative
screening level ones to eliminate wastes from further
consideration to more complex ones for .those wastes
which may be listed.
2. other Regulatory Determinations (hazardous waste
identification rule, hazardous waste combustion
emission standards, cement kiln dust regulatory
assessment, etc.)- Complex multimedia assessments to
determine appropriate regulatory strategies, and/or
standards*
3. Site-specific hazardous waste combustion risk
assessments (guidance and assistance to Regions and
States). Multimedia assessments range from screening
level to highly complex, depending on potential risk at
a facility.
III.. Legal Bffecrfc
This implementation guidelines document and associated
guidance..on risk characterization do not establish or affect
legal rights or obligations.. Rather, they confirm the importance
of risk characterization as a component of risk assessment,
outline relevant principles, and identify factors, that staff from
OSW should consider as they implement this policy.
The implementation guidelines and associated guidance do not
stand alone; nor do they establish a binding norm that is finally
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determinative of the issues addressed. Except where otherwise
provided by law, OSW»s decision on conducting a risk assessment
in any particular case is within OSW's discretion. Variations in
the application of this policy and associated guidance,
therefore, are not a legitimate basis for delaying or
complicating action on OSW or Agency decisions.
IV.
All risk characterizations prepared by OSW in support of
decision making at EPA are covered fay the Administrator's Risk
Characterization Policy., and this implementation • guidelines
document. Discussion of risk in all OSW-generated reports,
presentations, briefings, decision packages, and other documents
should be substantively consistent with .the policy and this
document*
OSW relies largely on Agency positions and documents for
many aspects of its risk assessments. Two key examples are the
IRIS data base and the "Exposure Factors Handbook1*. When
^utilizing this information, OSW depends on whatever is provided
in these documents and data bases. TO the extent that these
Agency sources do not yet meet the fall requirements of the Risk
Characterization Policy, .OSW*s assessments vill have the same
deficiencies. The Agency is working to ensure that these sources
will'be brought, into -compliance with the policy.
Risk assessment.information is often filtered through
several layers of management before reaching the ultimate
decision maker. In OSW, reasons should be given for filtering
out any risk characterization .information during .this process.
It is OSW policy to require that each risk assessor prepare
a risk characterization for each risk assessment. Each risk
assessment prepared by or for this Officeishould contain one or
F-39
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more sections on risk characterization at a level of detail
appropriate for the type of assessment. The risk assessor will
clearly identify the scope of. the assessment and the reason (s),
if any, for not considering certain factors outlined in the
"Elements" document accompanying the Administrator's Risk
Characterization Policy. The guidance to risk assessors, and the
criteria by which they can be judged, on this point, are that
they:
A. Clearly define the scope at tha assessment
1. Note, with a brief explanation, categories of hazard
end-points (including ecotoxicity) that are
specifically excluded from the review.
2. Also note populations which are specifically excluded
from review.
B. Cleanly define tha level of raviey used in fehia assessment:
1. Give an idea of the types and quantity of data sources,
•reviews, and databases that were utilized.
2. If it is an extensive review, it is especially
important to indicate all major sources of information,
and to highlight any major source not utilized with the
reasons why.
Documents that describe components of a risk assessment
(e.g., stand alone hazard or exposure assessments), even if
prepared as separate documents, will also follow the risk
characterization policy in that they .will strive for clarity,
transparency, consistency, and.reasonableness.
Documents related to.risk or any of its components which are
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submitted to this Office by EPA contractors or other EPA Offices
are expected to follow the Risk Characterization Policy.
It is OSW's policy that documents from sources outside'EPA
that this office relies on in preparation of risk assessments
will be augmented by adding risk characterization language to
meet the requirements of the. Risk Characterization Policy.
It is OSW policy to clearly explain any circumstances where
assessments, and other information such as IRIS, have been
produced in the past by EPA but which do not fully follow the
risk characterization principles. Additional guidance on how the
use of IRIS and other information systems and documents produced
by ORD and others, that serve as inputs to OSW generated'risk
assessments will be developed by the Science Policy Council..
This document will be updated when such guidance im received.
Documents submitted by the public to this Office that relate
to risk assessment or any of its components, including those that
support alternatives to EPA risk assessments, will be evaluated
in light of the Risk Characterisation Policy and this guidelines
document;
OSW will apply the general principles specified in .the Risk
Characterization Policy to its assessments of ecological risk.
Specifically, until detailed Agency guidance becomes available, .
risk characterization*-involving ecological effects developed by
this Program will strive to include a discussion of the strengths
and limitations of. the assessment and will also strive to achieve
the Risk Characterization values of clarity, transparency,
consistency, and reasonableness.
Assessments of benefits are not included in this
Implementation Guidelines. 'Although this Office acknowledges
that the principles of clarity, transparency of process,
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consistency,, and reasonableness apply also to analyses of
benefits, the Agency has not yet developed guidance for these
types of assessments.
V. Helationaliip of • rialr character jgation to riafc aaseasment and
As stated in the Risk Characterization Policy, "Risk
Characterization is the summarizing step of risk assessment. The
risk characterization integrates information from. the preceding
components of the risk assessment." In other words, risks can be
partially described by the individual components of a risk
assessment, but risk characterization' is a conscious and
deliberate process of bringing all important considerations about
risk into an integrated picture. Even more importantly, as an
integrated picture, the risk characterization is not simply a
reiteration of conclusions of the various components, but a piece
which focusses on how those components interact:.
"Risk characterization" is not synonymous with "risk
communication. The risk characterization policy addresses the
interface between risk assessment and risk management. -Risk
communication, in contrast, .emphasizes the process of exchanging
information and opinion with,, the public. While the final risk
assessment document (including its risk characterization
sections) is available to the public, the risk communication
process is better served by separate risk information documents
desioned for particular audiences.
Therefore, this risk characterization guidelines document is
written to provide guidance to the risk assessor for. his/her use
in explaining the assessment to risk managers. If this guidance
is followed, the resultant risk characterizations should also be
understandable to an educated and motivated layperson.
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Cfi'fcaria tor udging adeanagtr of gi.i aatMT-i.M
The criteria for judging the extent to which osw's risk
characterizations meet the Administrator's four values are
summarized below and further expanded in sections VII and IX of
this document.
A. Clarity of risk characterizations will be judged by the
extent to which:
l. Brevity is achieved and jargon is avoided;
2. The language and .organization of the risk
characterization are understandable to EPA risk
managers and the informed lay person;
3. The purpose of "the risk assessment is defined and
explained (e.g., regulatory purpose, .policy analysis,
priority setting);
4. The level of" effort (e.g. , quick screen, extensive
characterization) put into the assessment is defined
accompanied- by the reason(s) why this- level of effort
was selected;
5. The strengths and .limitations of the assessment can be
understood, without needing to understand the technical
details of the assessment. .To the extent they are
used, technical- terms are defined;
6. The scientific and policy bases, including biases (e.g.
to err on the side of safety), -used in the assessment
are clearly described;
7. Assumptions are defined and. understandable explanations
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are given for each policy decision made for that
particular risk assessment (e.g., use o£ default
assumptions); Agency policy decisions such as. the use
of linearized cancer models are generally not disussed
for each risk assessment; and
8. Unusual issues specific to a particular risk assessment
are fully discussed and explained.
B. Transparency of the process used to characterize risk will
be judged by the extent to which:
1. conclusions drawn from the science and technical
information are identified separately from policy
judgments;
2. The characterizations incorporate the principles of the
risk characterization policy (e.g., the -assumptions are
explained, the strengths and limitations of the
assessment and the "uncertainties are addressed in a
balanced manner);
3. The risk characterization does what it sets out to do
in an appropriate manner (e.g., it meets the expressed
purpose, the level of effort expended was appropriate
for the decision made, all relevant .portions of the
risk assessment paradigm were addressed);
C. The extent to which risk assessment conclusions and risk
characterizations are reasonable will be judged by whether:
1. They are determined to be reasonable by EPA risk
managers and the lay public;
2. All components .are well integrated into an overall
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conclusion of risk which is complete, informative and
useful in decision-making;
3. They are based on the best scientific information and
judgment readily available to OSW, with. sources
documented appropriately;
4. They use common sense and portray the use of science
and science policy to assess risk in a forthright
manner, acknowledging scientific uncertainty;
VIZ
Consistency in definition* and methods of assessing risk is
fundamental to minimizing confusion about risk' estimates
generated across the Agency. OSW attempts to ensure that risk:
assessments/ done within the Off ice are consistent in 'their
general approaches, selection of models, exposure assumptions,
and information sources. Since the state of the art and
availability of information are continually evolving, current
risk assessments may differ -(sometimes considerably) from those*
done in the past.
As indicated previously, there may be significant
differences in the level of detail" and complexity among osW risk
.assessments, depending on the magnitude of the decision, the time
available, and whether- the assessment represents an initial
screening or a more detailed assessment dictated by an initial
screen.
The following procedures used by OSW help to ensure that its
risk characterizations are consistent with characterizations
produced, by other part* of the Agency. They also serve as
criteria by which our success at ensuring consistency can be
judged.
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1. OSW relies on Agency-vide guidelines, such as those for
exposure analyses and health risk assessment.
2. OSW uses Agency-wide information systems, such as the
Integrated Risk Information System (IRIS) and risk
reference concentrations (RfCs) which are produced by
Agency-wide, consensus workgroups.
3. OSW*s risk assessments are done as part of the
development of regulations which require Agency-wide
work groups whose review includes the risk assessments.
4. OSW actively solicits input from other offices with
expertise in specific risk assessment areas; for
example OPPT for structure/activity analyses of
chemicals, ORD for exposure assessment parameters, and
OW for effects on aquatic'lifer.
5. OSW includes substantial input from the Regional
offices, in developing procedure* and guidance for
conducting site-specif ic risk assessments for hazardous
waste combustion facilities.
6. OSW solicits review and assistance from ORD and OPPT
whenever the .office needs to develop toxicity "numbers1*
for chemicals not. on the IRIS data base.
VIII. Jtvaluaiilpg off i.oa»ap«oi.fflg Olroyms'taBoes
The Risk Characterization Policy recognizes that **[t]he
nature of the risk characterization will depend upon the
information available, the regulatory application of the risk
information, and the resources (including time) available.*1 The
types of risk assessment* performed by OSW were described in
Section II. Considerations specific to OSW which affect the
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degree to which risk characterization can be accomplished include
statutory requirements, courtrbrdered deadlines, availability of
data and/or information {e.g., lack of health effects or exposure
data), and amount of resources available to conduct the risk
assessment and risk characterization.
XX.
Poll
The Administrator's March 1995 Risk Characterization package
provides a list of elements to consider when assessing risk to
human health (see appendix). That list of elements will be .used
by OSW. as the basic set of considerations for each risk
assessment and risk characterization that the Office performs,
recognizing also, however., that there will be reasons for
expanding or contracting that: basic set of elements to fit the
circumstances of a particular case. In modifying the- list of
elements, this Office will clearly state in the risk
characterization the reasons for adding to or subtracting
elements from that basic list* Such reasons may be written at a
general level to cover several elements.at once, or may; be
fc • . '
written at a very specific level-to cover a specific element,
• •>
depending on the level of decision being supported.
The following discussion expands on the summarization and
integration aspects of risk characterization, as a supplement to
Part Two of the pElements Documentp provided in the
Administrator's package. The discussion is meant to give further
explanation to risk assessors of the kinds of specific
information that may be relevant to OSW that will help decision-
makers form a clear, coherent, and integrated picture of risk at
the level of detail appropriate for the decision.
This section contains points' to'consider when characterizing
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risk. These points focus on the principles and key aspects of
risk characterization discussed in Part Two of the "Elements
Document". When special circumstances (e.g., lack of data,
resource limitations, statutory deadlines) preclude addressing
particular issues or factors contained in this section, such
circumstances will be explained and their impact on the risk
assessment discussed.
In. .addition to the criteria for clarity, transparency,
consistency and reasonableness discussed earlier in this
document. OSW has adppted the following policy that applies to
.the three principles and six key aspects of Risk characterization
addressed in Section II to help its staff comply with the
Administrator's Risk Characterization Policy. The following
points should help OSH's risk assessors characterize risk. These
points, also provide criteria that can be used by risk managers to
get the most out of risk assessment briefings and to evaluate the
assessor's performance in characterizing risk.
A. Summary of and Coirfj^ dflFlCP i*^ ^TP MiP jog Rialc Conclusions
in preparing risk characterizations for OSW, risk assessors
should present a brief statement of the bottom line of their risk
conclusions in simple clear language. In order to prepare
effective risk characterization*, risk assessors should give a
qualitative idea of the major risks and their confidence in the
estimates of risk and conclusions.
The risk manager should be able to read this and know what
are the major risks (or potential risks y to what individuals and
populations, and have an idea of whether the conclusion is
supported by a large body of data or if there are significant
data gaps. Explain in a qualitative narrative any quantitative
estimation of risk to assure that the reader understands the
meaning of the numbers.
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B. gyj^airy of Key Tsauea
Successful risk characterizations in OSW require that risk
assessors summarize in clear/ concise language the kjx issues,
conclusions, 'and rationale from each stage of the assessment
paradigm (i.e., hazard identification, dose-response evaluation,
exposure assessment, and/or the integration of these
considerations into a risk assessment) .
* IC«Y ig«qe is one that is critical in order to properly
evaluate the stated conclusion. The idea is not to repeat the
entire hazard, or exposure assessment, but to summarize and
identify those pieces of information that were critical to the
evaluation, so that the risk manager will be alerted to the major
issues and conclusions that are the bases of the assessment.
Short conclusion statements from the assessments can be repeated,
or, if the assessment conclusions are lengthy, summarized.
In looking at the whole risk picture there may be issues
which should be brought to the risk manager**; attention. For
example,' isL there a major imbalance in the assessments, such that
there is a strong case for hazard, but lack of data, or oreat
uncertainty for exposure; or vice versa.
Cut dance -ho fcha rimtc aagaBBorai Criteria for judging- how
T fche ehayacfcatH EA. T*iak in thaii* domniianta and brief ina
1. Briefly discuss the key issues from the reports, or data
sources, used to make the risk assessment; and
2. Look at the whole risk picture and bring issues to the.
risk manager's attention. For example', is there a major
imbalance in the assessment, such that there is a
strong case for hazard, but a lack of data, or great .
uncertainty for exposure, or vice versa.
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C. tfethods Used
Standard Agency methodology is generally followed to
generate risk estimates for each category of assessment conducted
by OSW. When quantitative risk evaluations are performed for
OSW, the resultant risk numbers should be narrated qualitatively
to ensure that the reader understands the meaning of the numbers.
When extensive risk assessments are performed, the risk assessor
is likely deviate from using default methodology. Such departures
should be highlighted in the risk characterization.
The mathematics of the risk calculations are not intended to
be fully articulated in the risk characterization. However, the
risk manager should be provided with qualitative "feel11 for the
numbers.
for judging fch» auccetig with which a rialc
tl)t« frfffal*' in brtiafilnq^ *|*d ift wgi-ttftT i
1. Explain the meaning of standard Agency interpretations
of risk values, (e.g., the hazard quotient) if they are
not. explained elsewhere.
2. Explain any specific methodology that might be easily
misinterpreted, (e.g., the use of ecotoxicity
population models)-.
3. If technical data are presented in numerical terms,
qualitatively discuss the data as well. In this regard,
the use of tables and graphics is strongly encouraged,
including sufficiently descriptive titles and
narrative.
D. smmnayv of fche Overall
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Risk Assessment:
. Discuss in qualitative terns, in clear, concise language the
overall quality of the assessment, and the major uncertainties
associated with each of its components. The'idea is to relay to
the risk manager in frank and open terms the strengths and
weaknesses of the assessment.
An example of possible strengths of an assessment would be
that the overall weight of evidence of the data indicates that
the quality and quantity of .data supporting the hazard and/or
exposure is high. There might also be general consensus within
the scientific community on certain points used to build the
hazard/exposure case. The risk manager needs to know the-amount
of uncertainty in each of the assessment areas, and in the final
risk.conclusions.
success in conveying fcVi^ afcy«*nerfc>m anft uncertainties
Rialc Assessment:;
1.. Identify any uncertainties in the "source term"
information.
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a) Identify what: other reasonable alternatives and
conclusions can be derived from the data set.
b) Discuss how other organizations (e.g., industry
and environmental groups) evaluate the risk and
the pros and cons of their evaluations, compared to
EPA's assessment.
5. Kake clear when:
a) precise conclusions cannot be drawn because of
uncertaintyi
b) conclusions may differ because of variation (e.g.,
when children exposed to a chemical are at a
different risk from adults exposed to the same
chemical because of their different
susceptibility);
6. Identify major data,gaps and, .where appropriate,
indicate whether gathering particular data would-add
significantly to the overall certainty of the. risk.
a) With.respect to toxicity information, OSH risk
assessors should ensure that~any significant
limitations.identified in the. Agency data bases
are. presented to the decision makers..
by if a toxicity-. "number11 was generated by OSW,
identify which other EPA- offices were involved in
the development and .review of the number and what
its*limitations are.
7. Indicate where scientific judgments or default
assumptions were used .to bridge information gaps, and
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explain the bases for these judgments/assumptions*
E. Put this Risk Assessment in Context with Ofchfty similar
Because of the potential for public misunderstanding through
inappropriate risk comparisons, "comparative11 risk discussions
(e.g., the risk of dying in a car accident compared to the risk
of dying in a plan |