EPA Region 10
Supplemental Risk Assessment
Guidance for Superfund
March 27, 1996
Prepared by: Region 10 US EPA
Office of Environmental Assessment
Risk Evaluation Unit
with the assistance of: ICF Kaiser
under ESATTID 10-9510-718
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FOREWORD
The purpose of the EPA Region 10 Supplemental Risk Assessment
Guidance for Superfund is to summarize important concepts from national
risk assessment guidance, highlight steps of the Remedial
Investigation/Feasibility Study (RI/FS) relevant to the risk assessment and to
identify specific deliverables that should be submitted to Region 10 during the
development of the baseline risk assessment. This guidance is a supplement
to the national Risk Assessment Guidance for Superfund, Volumes I and II
(RAGS) (EPA 1991c&d, EPA 1989c&d) and other national EPA guidance
documents related to the conduct of risk assessments (EPA 1992a, EPA
1994a). National supplements to RAGS are separate from this regional
guidance document and may be obtained from the relevant national office
listed in section 7.3 of this document.
This regional guidance applies solely to risk assessments conducted
at region 10 National Priorities List (NPL) sites. While this guidance is
primarily intended to clarify and extend the national RAGS, as interpreted and
applied by Region 10, in some cases (e.g., human health contaminant
screening), as noted within the text, regional guidance will not be consistent
with national RAGS. In such cases, unless other wise agreed upon with the
regional project manager (RPM), regional guidance should prevail.
Updates to this guidance relating to specific technical issues and/or
regarding particular relevant case study examples will be issued in the form
of the Region 10 Risk Report, a new, intermittent regional publication. This
guidance document, and subsequent issues of the Region 10 Risk Report,
supersede all previous risk assessment guidance issued from the Office of
Environmental Assessment and Superfund in Region 10. Copies of regional
guidance materials may be obtained from the Office of Environmental
Assessment Risk Evaluation Unit (206/553-8209).
Region 10 guidance is intended for use by RPMs and risk assessors
preparing human health and ecological risk assessments for CERCLA NPL
sites in Region 10. Other uses (e.g., risk assessments conducted at RCRA
facilities) may be appropriate, but should first be approved by the RPM.
This guidance does not constitute rule-making by the Agency, and
may not be relied on to create a substantive or procedural right enforceable
by any other person. Region 10 reserves^m right to take action that is at
variance with this guidance. ContextualfpUppropriate application of the
concepts presented in EPA Region 10 Supplemental Risk Assessment
Guidance for Superfund should help to create scientifically sound, technically
defensible and consistent risk assessments in Region 10.
For questions regarding this regional guidance, contact:
Dana Davoli, Region 10 Human Health Risk Assessment, 206/553-2135
Julius Nwosu, Region 10 Ecological Risk Assessment, 206/553-7121
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Table of Contents
1.0 INTRODUCTION 1
1.1 Scheduling of Deliverables 1
1.2 Focus of Risk Assessment 3
1.3 Regional Technical Guidance 5
2.0 RI/FS PROJECT PLANNING , jPT 6
2.2 Conceptual Site Model Jk.. JP?. 6
2.2 Preliminary Remediation Goals
2.2.1 List Expected Contaminants
2.2.2 identify Potential ARARs ...
2.3.3 Identify Risk-based Concentration
2.2.4 Present PRG information in a 7
2.3 Consideration of Risk Assessment Data
2.3.1 Use of Sampling Data for the Risk
2.3.2 Analytes and Detection Limits
3.0 Preliminary Data Analysis
3.1 Scheduling of Risk Assessment Deliyerables Durirtj
18
limlnary Data Analysis
18
3.2 Evaluation of Laboratory ContapmahtsainKJ^Iatural Background 19
3.2.1 Laboratory Contaminants . . , jlHt^.V?J|^.v^. 19
3.2.2 Natural Backgroujjf J^. . .'1-^^p^! 19
3.3 Risk-based Screening of Jpntaminj^ts: Hun&ri Health 20
3.3.1 Risk-Based Scijjjning: Sjjggested j§3proach 20
3.3.2 Chemical-Spjjjrfic Screening Criteria 21
3.4 Risk-based Screenin$f Ecological ... ^|pf 22
3.5 Revised Conceptual Site ModetfEtpOSUre Pathways 27
MAN HEALIIiRISK ASSESSMENT 29
of the BaWfeie Risk Assessment 29
29
Selection of Exposure Scenarios 29
31
of Exposure to Soil
hways of Exposure to Groundwater
athways of Exposure to Surface Water and Sediment
ating Exposure Point Concentration from Sampling Data .... 34
1.1 Calculating the "RME" Concentration
'.3.2 Grouping Samples
4.2.3.3. Risk Maps
4.2.3.4 Background
4.2.3.5 Non-Detects
4.2.4 Predicting Exposure Point Concentration Using Modeling/Estimates
36
4.2.5 Contact Rate, Exposure Frequency and Duration 36
4.2.5.1 Use of Standard Default Exposure Factors
4.2.5.2 Region 10 Default Exposure Factors
iii
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
4.3 Toxicity Assessment 38
4.3.1 Toxicity Reference Values 38
4.3.2 Toxicity Profiles .JP*
A _ _ •iJR' 39
4.4 Risk Characterization and Uncertainty Analysis JpK,W • 40
4.4.1 Exposure Duration for Noncarcinogenfc Soil Contamfnants 40
4.4.2 Risk Characterization Using RfCs ao&tfnits RHt&9
4.4.3 Summary Tables „
4.4.3 Uncertainty Analysis 33. J$.. .. :t$";-.,,. TV—& 40
4.4.3.1 Qualitative Uncertainty Atiffrysis
4.4.3.2 Quantitative Uncertainty A&HJJW
4.4.4 Summary and Conclusions . . .\^?PK 42
5.0 BASELINE ECOLOGICAL RISK ASSESSMENT , S • . . .^..Wv 43
5.1 Introduction ^&«V*>&. 43
5.7.7 Chapter Objective .$$$1^ ?%S&!j83$' 45
5.7.2 Roles of Parties Involved^^ ^^logical RfsfiAssessment 45
5.7.3 Technical Issues . . ^y^^tiS&fa&fa^ JTt 45
5.7.3.1 The "Tool Box" ,•/"
5.7.3.2 Site-Specfffc Case $fudie
5.1.4 Scheduling the&d$eline RisK Assesstftefil 47
5.7.5 Chapter Organ/zat/on . jjf Jl. 48
5.2 Screening ^ Jr. 48
5.3 Step 3: Problem Formulation
:,5.3.f Site ChdracterizatiofiZ
5.3.2 QuaitiatlveEvaluat
"asp?^,*^
. fc-iMH^ll--^*.^^
Parame(e/5 &f£oncern
ot Contaminant Release, Migration and Fate
49
50
51
51
5.3.3.1 f
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DRAFT Supplemental RAGS
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5.5.3 Estimation of Exposure Point Concentrations 64
5.5.4 Toxicity Tests 66
5.5.5 Toxicity Bioassays ^ 67
5.6 Step 6: Field Investigation 4fe • • • &T • 68
5.6.f Site Investigation and Ecological Effects Asseajm/gm. 68
5.6.2 Field Studies j^. . . . 68
5.7 Step 7: Risk Estimation and Characterizatic
5.7.1 Risk Estimation and Uncertainty Analysis
5.7.1.1 Current Adverse Effects
5.7.1.2 Future Adverse Effects
5.7.1.3 Risk Calculation
5.7.1.4 Uncertainty Analysis :t, «,v>\ 74
5.7.2 Risk Description and Interpretation ot Uncertainty 77
5.7.2.11nterpretation of Uncertainty
5.7.2.2 Conclusion with Evaluation of EcotogJ^at^S^nificance
5.8 Step 8: Risk Management ^MfX '^'kf 78
6.0
7.0
RISK ASSESSMENT TASKS FOR THETFS . . ! ^f^xj,, . . .^T. 80
6.1 Risk Evaluation of Remedial Alternatives . ,..^ ,„.,-;/ 80
6.2 Scheduling of Risk Assessment DeliverableS for the FS 80
RESOURCES dB^' ' ' ' ^ & 81
7.1 Human Health Risk Assessment Resources 81
7.1.1 Agency Gttffieiines ft>jr Risk Assessment 81
7.7.2 Referencesfor ToxtetjyA$&&sment 81
1or ExposunTASsessment 82
sment Guidance 82
r Incineration 83
^ _ ^ % • "- __. , _ % v••• -. _.-_
7.2 Ecofogicai Rjsk Asses$m«Rt Resources 83
84
Values 85
7.2.3 Uncertainly References 85
.3 Where to Obtalri Documents 85
87
8.01REFERENCES
A Calculation of Human Health Risk-Based Concentrations for Radionuclides
Appendix B Summary Tables of Human Health Exposure Factors
Table B-1 .a Residential RME and Average Exposure Factors for Superfund
Human HeaJth Risk Assessment
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DRAFT Supplemental RAGS
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Table B-1.b Industrial RME Exposure Factors for Superfund HH Risk Assessment
Table B-2 Exposure Factors Used for Risk Assessment at Hazardous Waste
Sites: Details of Differences Among Programs
Appendix C Risk Report Technical Issues
Appendix D Risk Report Case Study Summaries]
Attachments
3L
Attachment 1 Human Health Risk-Based Concentrations Tor Water
vi
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List of Common Risk Assessment Acronyms
ARAR
AWQC
STAG
CERCLA
COPCs
CSM
EPA
ERA
FS
HEAST
HHEM
HHRA
HI
HQ
IRIS
?PM
SARA
TRV
TQ
UCL
UTL
applicable or relevant and appropriate requirement
ambient water quality criteria
biological technical assistance
Comprehensive Environment
Act of 1980 (Superfund)
contaminants of potential
conceptual site model
[United States] Environm
ecological risk assessment
feasibility study
Heath Effects Assessment Summary Tables
Human Health Evaluation Manual of tfte RAGS
human health
hazard index
hazard quotient
Integratedijfisk Information
"ipeosation and Liabilit
ection Agency
produces a 50% rportality rate in a given species
servedCJdverse effects level
>-$<£. . .
conuMjmnant U
mum cc^am&iantlevel goal
nal Oil a^d HfZardous Substances Pollution Contingency Plan
al Priorities" List
adverse effects level
rernediation goal
responsible party
Risk Assessment Guidance for Superfund
ased concentration
erence concentration
reference dose
remedial investigation
reasonable maximum exposure
record of decision
regional project manager
Superfund Amendments and Reauthorization Act of 1986
toxicity reference value
toxicity quotient
upper confidence limit
upper tolerence level
vn
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
1.0 INTRODUCTION
As stated in the foreword, the purpose of the Region 10 guidance i
concepts from national risk assessment guidance, highlight
Investigation/Feasibility Study (RI/FS) relevant to the risjsflasses
deliverables that should be submitted to Region 10 du
assessment. Updates from the previous (1992) version
in text box 1-1. The anticipated users of the regional guffil
identify stages of the remedial process in which a riskva
technical staff who write or review risk assessments.
evelop
e Regio
ice are
ssor~should be
s important
the Remedial.
identify specific
baseline
^y * v.-^ %v
The methodology recommended for use in developing the baseline risk assessment is
described in the Risk Assessment Guidance For Superfund, Volume?: Hufoan Health Evaluation
v^>^^^ jyf s «. «A Y-^y-yj} *•'"'&•
Manual, Part A (RAGS HHEM) (EPA 1989d) an&tfgfome J££fjvironmen&t£valuation Manual (EPA
1989c). Parts B (EPA 1991c) and C (EPA 1|p^of th|;|{«rnaf1 Health" Evaluation Manual (HHEM)
provide guidance on the use of risk assesjffient in tttl FeWitaBty Study. Additional ecological risk
i"J" > '•'•'SS "sv f
assessment guidance can be found JmJEhe Framework for geological Risk Assessments (EPA
1992a), the draft Ecological Risk Assessment forSuperfund:/j*rocess for Designing and Conducting
Ecological Risk Assessments (Fjj*'1994a)'and the ujseoming EPA Risk Assessment Forum's
Ecological Risk Assessment'Guid&lines (notyet avaflatjfe at time of publication).
"§?" '"*"•' '••
Box 1-lXW&i9nts of Revised Region 10 Guidance
Ecologlcai Risk AssessmantCuidance (Sections 3.4 and 5.0)
s f
Revised Radipftyclide PRG Equations (Appendix A)
(•
•Based Screening Concentrations (Attachment 1)
Updated RfBources and References (Section 7.0 and 8.0)
w
Fin Risk Assessments (Section 4.4)]
inical Issue Papers Section (Appendix C)
Case Studies Section (Appendix D)
1.1 Scheduling of Deliverables
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
The organization of this regional risk assessment guidance is consistent with the Region 10
Policy, Conduct of Remedial Investigations and Feasibility Studies (EPA X 1990). This regional risk
assessment guidance identifies certain items as nsk assessment interim deliverables which should
be submitted in advance of the baseline risk assessment. Risk assessment ifltenn* deliverables can
be included as parts of the Site Characterization, Work Plan, and. Praficninary Data Analysis
"•M ' ••-.-. -. x
documents (see text box 1-2), or may be submitted as separate technical memoav according to ths
needs of the particular project. The EPA Remedial Project Manager(RPftfl) will
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Text Box 1-2 Integration of Risk Assessment Deliverables in RI/FS Process
Phase I. RI/FS Project Planning
Scoping
Conceptual Site Model (2.1)
Preliminary Remediation Goals
RI/FS Work Plan
Phase II. Preliminary Data Analysis / Site CharactenzatfoaStimmary
Evaluation of Lab Contar
and Natural Bac| _
Risk-Based Screen injpof Cont
Revised ConceptuafSite
Exposure pjmways (as needec
Revisions tojfjic Plan
Ecological^Mhing.Lfgil ResultffS.1 & 5.2)
Ecological tppoint Section (5j* 5.4)
w
ility Study Reports
(4.0 and 5.0)
uation of Remedial Alternatives (6.0)
Note: Bold Kerns are risk assessment deliverables. Parenthetical references
indicate relevant sections of this guidance document.
"Assessment
stalled EPA guidance is available on the subject of risk assessment in general as well as
Superfund risk assessment in particular. (See section 8.0, Resources.) We hope that this regional
guidance will be useful in pointing out relevant guidance for specific issues. However, guidance
does not serve as a "cookbook" or establish an invariable pattern, but is subject to interpretation.
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
National Priority List (NPL) sites in Region 10 vary in size from a few acres to square miles, vary in
number and type of sources of contamination, and vary in presence of ecological receptors or in
potential for exposure to human populations. The risk assessment processed the report produced
will not be exactly the same for any two sites. The process will be modifjw as s^propnate to each
project. The professional judgement of the project manager, ri$J|assess^^cific aspects of
the risk assessment. See RAGS HHEM (EPA 1989d), chapflt 3, for adrfnal^^t^tqn regajdjffg
goals and focus of the human health risk assessment. Ideally, the rii^^ssessrnSllpfoc^s»swtl be
S
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
1.3 Regional Technical Guidance
To avoid overly frequent update releases of this guidance the rej:
publication to address evolving risk assessment technical issues. The
be released intermittently in response to selected human
technical issues. It will be a separate publication from the,
will provide more in-depth, technical discussions than
Review should be placed under Appendix C, 'The Tool;
similarly be comprised of special releases of the Region^
case studies related to human health/ecological risk assessr
e an update
Vs/f Review will
risk assessment
News,
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
2.0 RI/FS PROJECT PLANNING
Text Box 2-1 Risk Assessment
Interim Delivefables During
,, RJ/FS Project Planning
\
Conceptual Site Model {2.1}
..Preliminary Remedialon Goals (2.2)
The risk assessment information considered
in the RI/FS project planning is often included in
primary documents, such as a scoping document
and work plans. The interim deliverables specified
in text box 2-1 should be submitted for review in
advance of the larger documents, and the
information later incorporated into these larger
documents (i.e., the baseline risk assessment). The
specific schedule is up to the discretion of the RPM.
However, since both the finalized Conceptual Site "\;
Model and the Preliminary Remediation Goals will impact tine progress of the risk assessment, these
deliverables will correspond to decision points in the risk assessment process and should be
submitted in a timely fashion. For sites wftere the potentially responsible party (PRP) will be
conducting the RI/FS while an EPA contractor will be doing'the- riskassessment, it will probably be
necessary to submit separate risk assessment deftverables/rFor example, the risk assessor will
need the list of expected contaminants, submitted by the«PRP, in order to prepare preliminary
remediation goals (PRGs). In tum^the exposure pathways #bm the conceptual site model will have
to be presented in time for the>PRfMo consider nsX assessment data needs in preparing the RI/FS
\ %\ -,-.''
work plan. {8&e also the directive on risk assessment for PRP sites (EPA 1991f)).
2.2 Conceptual Site Model
The Site Characterization Document, or another document used at the scoping stage, should
present and discuss a w> ""
should Be in the form of ^froftr effort showing site characteristics, including contaminant sources,
y '>^->, &"
release mechanisms, tra»$pajf routes, receptors, and other information as appropriate. Iterations
of tfis model will be carried through the work plan and baseline risk assessment report. As stated
*H Jiif
ofl|age 2-9 of the Guidnce for Conducting Remedial Investigations and Feasibility Studies (RI/FS
?, Conceptual site model should include known and suspected sources of
Sfitamination, types of contaminants and affected media, known and potential
routes of migration, and known or potential human and environmental receptors.
This effort, in addition to assisting in identifying locations where sampling is
necessary, will also assist in the identification of potential remedial technologies.
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
A generic conceptual site model diagram taken from the RI/FS guidance is presented as figure 2-1.
This may be used as a starting point, although other effective formats, graphical or pictorial, are
possible, for example figures 2-2 and 2-3. The generic model should be modified to jiitu'de as much
site specific information as possible. Text accompanying the diagram should sufficiently address
specific sources and receptors at the site. More in depth discussion of ffieVcSSgical components
of the conceptual site model is presented in section 5-4.
The development of the conceptual site modi[ will pmvfde a b
identification of exposure scenarios to be evaluated in fh%]|ase|irie risk assess
human and ecological components of the conceptual sli,model should be shown in a single
diagram. This will allow both the risk assessor and the risk tnaniagf rto put potential threats in to
perspective as well as to avoid redundancy in evaluation of components Cpnnected with both human
and ecological health (e.g., contaminant uptake by fistrwhich may &e"lng|sl;ed by humans). RAGS
HHEM (EPA 1989d) chapter 6 and Standard^£$ftwtt^jjjt&osurB F&jjjtjrs (EPA 1991h) provide
guidance on human exposure scenarios andVathways^^alKdoesjiection 4.2 of this regional
guidance. Ecological exposure scenarios an? "discussed in^rte Wiidtife'Exposure Factors Handbook
(EPA 1993a).
A written presentation of rjjipin and ecological exposure scenarios and pathways that will
^pj? 'vasw *\$>
be evaluated in the risk assjissq|ent should p&prepared during RI/FS planning. The exposure
scenarios a**d pathways,willBVased in developMg Ihe work plans so that risk assessment data
•^S f % *N * O?M,S %-.^ NJ. ^ S J.W.AWA \ ^.-
needs are addressed. Selection of exposure patfiways will rely heavily on the conceptual site model.
Presentation ;flf selected expbsjure:;pa|hways may simply be notes or text accompanying the
"<:•.•. ~~ %A" £vi\y& \ \-. s.
conceptual site model, anql should: include reasoning for including and excluding various pathways.
Discussion of exposure scenarios m^|%hen appropriate, be accompanied by site maps showing
locations oi&ources ahdreceptprs, of can refer to maps in the scoping report or work plan.
Identification of elplpfre scenarios and pathways at this stage in the process may be
defiled, or may be morejfeneral, depending on the amount of information about the site available
f Jiiithe scoping process. Scenarios and pathways may be modified as more information is
d during tjMpfl. Due to the increased complexity of the ecosystem and the interaction of
jical exposure pathways and scenarios present may be more complex than the
Dsure pathways. Hence, to clearly communicate the potential ecological exposure
pathways present at the site without excessive detail regarding the various components of
ecosystem interactions that may occur at the site, it may be helpful to discuss the different
components of the ecosystem that will become the backbone of the conceptual site model and
ecological assessment endpoints. The final version of the exposure scenarios and pathways
-------
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Figure 2-1 Example Conceptual Sit^M
-------
SOURCE
RECEIVING MEDIA
MIGRATION PATHWAY
EXPOSURE MEDIA
RECEPTORS AND
ROUTES OF EXPOSURE
PLATINa WASTES
EXPOSURE PATHWAYS POTENTIALLY COMPLETE UNDER EXISTING CONDITIONS
—*• SURFACE SOILS »NONB »• SURFACE SOILS
•*- WIND EROSION
•*• AIRBORNE PARTICLES
DIRECT DISCHARGE TO
SUBSURFACE SOILS
VIA SEPTIC SYSTEM
LEACH BED
• LEACHING AND TRANSPORT
BY PRECIPITATION
INFILTRATING THE GROUND
-QROUNDWATER
MIGRATION OF LIQUID
- WASTES DIRECTLY
TOOnOUNDWATER
*- SITE WORKERS AND
8ITC VISITORS
• Dftnul contact
tand-to-moutti oonted
SITE WORKERS. SITE
VISITORS, AND NEARBY
RESIDENTS
• HMMon
RESIDENTIAL AND
COMMERCIAL USERS OF
GROUNDWATER
• IngMfen «i dHnMng water
RESIDUAL PESTICIDES
•SURFACE SOILS
-»-NONE
-*- SURFACE SOILS
SITE WORKERS AND SITE
VISITORS
• Darmal contact
• IngeaOon via hand to-mout*
•*• WIND EROSION
-*» AIRBORNE PARTICLES
SITE WORKERS.
SITE VISITORS. AND
NEARBY RESIDENTS
• Miatalon
31
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Figure 2-2 Example Graphical Conceptual Site Model f;
So
o> (/) o
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
10
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Figure 2-3 E
2.2 Preliminary Remediation Goals
tual Site Model
Prelinwary pftmediaticnrt'ij^sj^BGs) are categorized in two ways: (1) ecological vs. human
health, and (2)(#sk»&a6ed (e.g. ^®bif y«i- regulatory (e.g. ARARs). The latter separation is not
* \. '? ^ iT ^ ~^
always distinct {le>g%s)ogical or human health protection and whether it is a regulatory
valueland/or a risk-based^ilufFIt is important that as much information available for both ecological
i heath threajflfoe presented in this context. The Regional Policy on Conduct of RI/FS
jjjjjf
.X 1990) emphajyzes that preliminary remedial action objectives be developed at the initial
group mee
11
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
•*#"" •• J
&.\
Steps involved in developing PRGs are presented
in text box 2-2. Part B of the RAGS. HHEM,
Development of Risk-Based Remediation Goals, (EPA
1991c) addresses the need for early consideration of
risk-based clean-up numbers. It presents simplified
equations for calculating risk-based PRGs. However, the
radionuclide equations in section four of RAGS HHEM
Part B have been updated; new equations are given in :
Appendix A. of this document. Human health screening
level risk-based concentrations for a large number of
chemicals are calculated and released semiannually by
EPA Region 3; a compilation of these values at the time
of this document's release can be found in attachment 1
of this document. Values for a limited number Of
contaminants, which take into account the additional
transport pathway of migration of contaminants in soft to
groundwater, may also be found in the So/7 Screen/no
— ^ ";y
Guidance (EPA 1994b). Ecological Jskmformatjpi may be
such as those listed in text box 2-Ssso it is essential to
•&
ecological values may be found in section 7,3,,
The risk assessor should gather inftfifnltion, perform necessary calculations and present
information,, separated by media, In tabular form noting the following:
Text Box 2-2 Steps in the
Development ofJIRGs
•.?
List expected contaminants
ij.e sources
^'
^ calculate "risk a!
Identify RBCs
* assemble toxicrty information
^compile/calculate RBCs
^ »;K Present information in a table
Vfii^i/
nd in a variety of reference materials,
arly site sources. Other references for
y-B-^ v.% , , •
Regulatory PR<3{s^A^ARs) for each exposure pathway of concern,
risk at ARAR
arily for human health values), and
• risk-based P|?G(s) (RBCs) for each exposure pathway of concern.
iU,agreemej|)#ith the RPM on which risk-based PRGs will be used for comparison and risk
in the risk assessment is essential in order to avoid unnecessary
later stages of the risk assessment. Although ARARs are not part of the baseline
risk assessment, it is often useful for some of the management-related purposes noted below, to
present these numbers together with the risk-based concentrations.
12
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EPA Region 10
DRAFT Supplemental RAGS
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The primary function of the completed PRG table will be to anticipate the range of risk-based
concentrations that may become goals for site clean up action. Early consideration of these
numbers allows planning and evaluation of remedial alternatives to begin befojplhe remedial
investigation report and baseline risk assessment are complete. It is exp|||ted:;:|ilf the PRG table
will also be referred to by managers and technical personnel atiiirious sj^|||;:i|p|he RI/FS process,
for various purposes. An important use is evaluation of adequacy of ana||i|p||||thods to provide
data for risk assessment: method detection/quantitatior^flmits can risk-baj!d
concentrations. (See also section 2.3.) Also, as Rl dataAomes^afable,
of contaminants in site media can be compared to risk-based ^concentrations to iden^^Halminants
of concern for sampling in subsequent phases. The risk-b»e¥oOocentrations will also be used in
screening contaminants for the baseline risk assessment; ,{See allS chapter 3.)
* '$ **s.
Project managers and other staff should be aware that the'debased concentrations
presented at this stage are preliminary. Changed may OfiW if new on|yfsed toxicity information
is obtained, and/or if site-specific modifications In exposure assumptions are appropriate.
Consideration of cumulative exposures to multiple pathways^aid conllarn'inants may affect risk-based
numbers. Note that risk-based concentrations provided in Attaehreifit 1 do not protect for ecological
effects, migration of contaminants tO||j^)tjndwatgf..or inhalation exposure pathways. To adequately
confront human health concemsjlpfatile cojji|bunds mayYieed to be addressed from a different
perspective. Risk-based copcej||rations fp||p||..|f|:«particulariy susceptible to change, because
assumptions ^jout human;e^s4ffe to contli||||ilp"soil depend on several site-specific factors.
Soil characterisics, geofb^jeajj anicl/neteordl6|fca? conditions at the site, as well as chemical and
physical properties of contaminant? affect their fate and transport. These factors, along with site
•>% v.,£ ^ "^iSi """NV 'Siv^fti*
use, determine the relative importance 'of various routes of release, receptors of concern and
exposure pathways (reteasejo air, migration to groundwater, incidental ingestion, dermal contact)
in determining nsk-based^c-als for soil.
2.2. fist Expected Cojjimfnants
i
The first step irj^veloping PRGs is to assemble a list of potential site-related contaminants.
.on informati|ff about the site history, and on analytical results from Site Investigation,
iment, or other sampling efforts prior to the Rl, a list of chemicals expected or
lent can be compiled. Resource materials identifying contaminants expected to be
associated with specific industries or sources can be consulted. (Resources include Appendix II of
the Dafa Useability Guidance (EPA 1990b) and guidance for specific categories of sources.) A
written discussion of site information used in compiling the list of expected contaminants should be
provided somewhere; the discussion may be part of the scoping document or conceptual site model,
13
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EPA Region 10
DRAFT Supplemental RAGS
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or may accompany the table of PRGs. The list of expected contaminants may be lengthy for sites
with complex sources. Chemicals may be added to or deleted from the list as more information
becomes available during the Rl.
2.2.2 Identify Potential ARARs
Chemical-specific standards for soil, water, and;'air, as specified\ift federal or state
•• »> '^ ",?~;x. '> ,-\ «/
regulations that may become ARARs, are identified for cacti potential contaminant (ARA1? guidance
is provided in EPA 1988a). In the interest of limiting effort duringjscbping, the RPM may determine
that identification of the obvious federal standards, Maxhr&u^ Contaminant Levels and Maximum
Contaminants Level Goals (MCLs and MCLGs) for water an*3 Ambient Water Quality Criteria
(AWQC) for surface water, is sufficient at this stage. Note that ARAR^ujkier the Washington State
Model Toxics Control Act (MTCA) (WDOE 1991) indude some"co^rifrations defined in the
* ' * ....' % •• >. :• ••>»»»»»>»•»>
regulation, and some concentrations calculated using; j
Human health risk at ARARs is calculated by treatinoAFSAiR: concentrations as exposure point
%> J ^ &&"$&* %w- ftp
concentrations in risk equations, .u||rig standard defaaft^^xposure factors. Risk-based
concentrations for each contaminant;!^ calcul&ted by reajf&nging the same equations. For this
step, the concentration correspondj*g to a tafgset nsk ol.jjjr6 and 10"4 for carcinogens, and hazard
quotient of 1 for non-cancer effecta,js calculated Relevanfequations can be found in RAGS HHEM
part B and, fo/^dionuclides,: iF^Appendix A... N0 calculation of ecological risk at ARARs is required;
howevecv,$h"oijfeJ^$uch an arjafy«i$ be deemed useful in decision making for the risk assessment, an
analogue type of approach may be used. The use of analogues to estimate toxicity to aquatic
organisms is d0$«r&e<$ toy EPA's 0$c$ Of Toxic Substances (EPA 19880-
2.3.3 Identify Risk-based Concentrations
'
^ "
'Risk-based screenjjngl^aiues for both ecological and human health have been calculated and
arjllpailable for many cpitaminants. As noted above, Region 3 RBC tables are a good source of
health protectiyjpalues, and are generally adequately conservative screening concentrations
|t sites. E^cjiJX threshold values are listed in a recent EcoUpdate (EPA 1996), but when
¥, care should be taken to insure that they are adequately conservative for site-
ins. Other sources of potential screening values are listed in chapter 7.
14
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Text Box 2-3 Ecological Toxicity and Exposure
References
USFWS Contaminant Hazard Reviews (e.g. Zinc
Hazards to Fish, Wildlife, and Invertebrates: Asynoptic
Review. Fish and Wildlife Service, US Department of
the Interior. Biological Report 10; Contaminant Haza
Reviews Report 26: April 1993. )
AWQC values
NOAA Screening Guidelines
AQUIRE database
Wildlife Exposure Factors Handbook (EPA
current ECO Updates
Summary of Guidelines for Conta
(WDOE, Publication #95-308)
Screening Benchmarks for
Assessment (Oak Ridge
For some contaminants,
and some media, pre-calculated
values will not belivailabie. In
such insjlncesjloxicity data must
and risk-based
Hums
be
in'£ •• ••'' ^
medium (soil, 'gfOimdwi&ter, su
2.2!€onsideration of
analysis activities undertaken during the remedial investigation should provide
/aluate all appropriate exposure pathways and chosen ecological endpoints for
"assessment. The sampling plan should be designed with all data uses, including risk
assessment, in mind. Hence, risk assessors must be involved in the development of data quality
objectives related to the risk assessment. Development of data quality objectives is not limited to
concern for the precision, accuracy, representativeness, completeness and comparability of the data.
Data quality objectives also relate to determination of:
15
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
• types of laboratory analysis used,
• sensitivity of the analytical technique,
• detection limits,
• confidence limits, and
• the resulting data quality (ATSDR, 1994).
Specific risk assessment aspects of data quality objectives 'am- discussed in the following
subsections.
2.3. 1 USB of Sampling Data for the Risk Assessments
j.. ..
The work plan should show that%lhe data needed to evituate each exposure pathway
•f * •) %«." % "«•. -.V-J?1
identified for the site will be collected. In the section of tJie.;..work plan that discusses the risk
assessment, the association of each pathway with specific" samples should be spelled out. The
information provided should answer the following types of questions: Will groundwater
concentrations be averaged over time for riste£SSessmen1? If so, how many rounds of data will be
collected? Affe ecological fe
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EPA Region 10
DRAFT Supplemental RAGS
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site use history and expected contaminants. Judgement of the RPM, chemist and risk assessor will
be used to evaluate advantages and disadvantages of available methods. Appendix III of the Data
Useability Guidance (EPA 1990b) compiles information on various janalyticmethods and
associated detection limits, listed by chemical. Information developed d
particularly RBCs and PRGs for expected site contaminar^Lwill
methods. For samples that will be used to establish .gpfiure
assessment, results are more useful if detection limit|lmeet
adequacy of detection limits should be evaluated in tljpwork
expected contaminants and comparing the method detection of 'quantitation
oping process,
when choosing
pound
with the appropriate risk-based goal for that chemical in that medium^. This does not mean that every
sample must be analyzed with the method achieving the lowest ipossHb^e detection limits. Issues of
cost and other data uses will affect the method selected. ;?of ^example, at locations where
**&&&&' ff
concentrations are known or expected to be high, the jjpstsensitive rfiethbd i^ay not be necessary.
17
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EPA Region 10
DRAFT Supplemental RAGS
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li, _\
•5 sv% \- ••••••' A^
3.0 Preliminary Data Analysis
, V
Extensive discussion on evaluation of data for use in risk assessment is provided in chapter
5 of RAGS HHEM (EPA 1989d) and in the Data Useability Guidance (£PA 1990b). Judgement
v ' ' &#**x*>*s#
regarding the needs of a particular project should be used} in interpreting! this guidance. The
discussion below highlights some important issues.
For many Superfund sites, a large number of
ecological and human health threats posed by these the,
\% si
degree and distribution. Some contaminants, often referfi
and/or more encompassing threats than others, and will si
w$F jwSSvwAy v w, ssv.5jt>s
Elimination from the baseline risk assessment of common-febofai<»y^contaminants, natural
background elements, and chemicals presenting Jp§ nsk should,tp:slCQn|ucted in a systematic
manner, as presented in 3.2 and 3.3 below, or «sing pthera.cceptabfe:;fiatfonale approved by EPA
h-v**^w>s» \; «;s"^?s\ «"&*
Region 10. It is suggested that this step be cawed out. in advance of tfte baseline risk assessment.
etected mf^ie^ffleaB*^ The
ntaminants pre$^>wff vary in
'9$ the "drivers" will pose greater
:r\'%s
Erection of the risk assessment.
3.1 Scheduling of Risk Assessment
minary Data Analysis
Text Box 3-1 Risk Assessment IntetlfltDeli
^During PreJtrtfna^y Data
\"*v\ ^^ "•"•
N^*.^\_ S W.« -.\SVSSS\-. %-, %< vIs-.vK'.vJw.wSjy'
* iii&iittaikm of Laboribty^otttaminantsTimid Natural
" "
Section 3 describes
the content of deliverables,
listed in text box 3-1, that
will be submitted after Rl
sampling results are
available but before the
RI/FS and baseline risk
assessment are submitted.
All of the information called
for in section 3 can be
compiled and submitted to
the RPM in one package,
along with other data
reports, if convenient. The
timing and length of these
deliverables will vary depending on the needs of the site. If additional sampling events will be
planned based on results of early rounds, timely reporting of risk-based screening and revised
exposure scenarios will be important. These should be submitted as soon as possible after data are
available. Risk-based screening can also be used to identify unusually high risks, for which the RPM
Risk-based Scrsdning of Cd'stainlnahts (3.3 & 3.4}
ised Concdfs^lle.ModelTExposure Pathways (3.5)
v^tei^i\
Revisions to Wory^^
Ecologicaf ScreeM»g Level Results (5.1 & 5J2)
Ecological E^Jpoint Selection (5.3 & 5.4)
18
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
might want to consider early action. Documentation of the logic used in reducing the number of
contaminants to be carried through the baseline risk assessment must be included in the final risk
assessment. This can be accomplished by including a copy of the risk-based screjpig and other
deliverables from the preliminary data analysis as an appendix to the baseHne reassessment.
For some projects the preliminary data analysis deHye/ables may ip O^Jttgd entirely. Trj
may occur when previously agreed-upon schedules do not jsrflow for addjtfohaf^BCte of docur|$lfit
review. Also, some of the interim deliverables called for below may not be necessary if RoaddJSonal
sampling is anticipated, and if the conceptual site model ancf kfeniigcation of exposure scenarios and
•. -. "'&*'
pathways in the work plan are acceptable and do not require;|.revision. In these cases, the
information called for in section 3 below will be submitted as part of "the baseline risk assessment.
The Region 10 risk assessment staff does not recommend skippingtee "Risk-based Screening" and
"Revised Conceptual Site Model/Exposure Pathways" interim stepsl-'"ZSfatt potential problem is that
if risk-based screening and specific exposure and toxicity information is not submitted and approved,
•, '•'•Kw.''^ 1 j ^ s% s ^
errors or gaps will be carried through the bas«ITne risk assessment. /"
For PRP-lead sites, again the
will need to be provided as a delive
risk assessment data analysis ta
3.2 Evaluation of Labo
ntamrn
%• v. < ^ v. lA^vWivi^, •
3.2.1 Laboratory Contaminants
f T ... -f,f.f
of the schedule may be different. Rl sampling results
the nWassessor before he or she can proceed with the
atural Background
Contar
among site risks. As^
include-'dcetone, 2-butar
from'Me risk assessmer
id into samples during laboratory analysis should not be considered
in RAGS HHEM section 5.5, common laboratory contaminants
lylene chloride and phthalate esters. These may be eliminated
Seated in RAGS HHEM page 5-16:
...if the blank cepains detectable levels of common laboratory contaminants, then
the sample rejips should be considered as positive results only if the concentrations
the sam^Pexceed ten times the maximum amount detected in any blank.
Nstufttf'Background
RAGS HHEM page 5-19 states:
If inorganic chemicals are present at the site at naturally occurring levels, they may
19
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
be eliminated from the quantitative risk assessment...comparison with naturally
ocurring levels is applicable only to inorganic chemicals...
%s5»
r?
Determining whether detected concentrations of inorganics represent natural background in a
medium is a site-specific issue. Appropriate number and locations of .&a;Ckgit)\jnd samples are
determined by the RPM and geologists. Interpretating sit&Jiata cofflpii^J&^ackground data
should be discussed among project managers and scientislsand addre«i«djlf*lhe,RI report.
is unclear at the time the preliminary data analysis is conducted whet&er i
anthropogenic in origin, they should be carried through th^baseli^
consideration of the issue of background in the FS. Althoii^riilt«fal background efem&nrtiTrnay be
excluded from the baseline risk assessment, at some 3&&jfcft'mg. FondSX assessments submitted to Region 10,
a screening process compadng^ncentra^o^J<>~;7tsj^based concentrations as outlined below is
suggested
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EPA Region 10
DRAFT Supplemental RAGS
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detected at the site to a risk-based concentration calculated using a conservative target risk, based
on calculations utilizing standard default exposure factors. The target risks specified here were
chosen based on lower end of the 10" to 10"6 "risk range" specified in the NCP (EPJ^l990d). The
assumption used is that if no single sample exceeds a concentration representing^ human health
risk concern, total exposure to the contaminant from the site wj^not be of qoinspm. The "screening
risk" deliverable should include tables dearly showing compariSW^used/v^th^C^mns showing risk*
based screening concentration and maximum concentration on sit^ih eacJTm'Wliiim for elch
^ -V\/
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EPA Region 10
DRAFT Supplemental RAGS
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groundwater; these pathways are addressed in the EPA Soil Screening Level Guidance (EPA
1994b).
Five inorganic constituents which are often analyzed for but which are ratf associated with
toxicity to humans under normal circumstances -are calcium^, magnestttm* potassium, iron and
' «*?<». ™y^. v
sodium. No quantitative toxicity information is available lo&tnese elertttSJtfcS from EPA sources?
These five elements can generally be eliminated from the human health risk assessment at
W * -.^ sjj-jy" •• AV. •• •- --\
screening stage based on qualitative judgement.
3.4 Risk-based Screening: Ecological
Like the
human health
screening, the
ecological screening
process includes the
identification of
contaminants of
potential concern.
However, unlike in
human health^ nsk
which the*flW5fcptor
is implicit to- the
process,
ecologica^'
assessrJint
re
P,
rv
'•'^s$ss8iiigffi*^
identification of both
contaminants and
receptors. Text box
3-3 outlines the
T ?\
1?" -..{i.--. -I.- ,H»5,^ ^,
List maximypfl concentration: of eacfc ^ernical in each medium.
\^ s$% •••• '\v^: '•'•'•'•'• ^
Compaq to risk-ba^ed conceRtFation
.^s^a&SiS11' . f-s^
cherflicils if
-• tloncentratfOfi exceed^ iSreening concentration for given medium
HQ<1
nt Hls<1.
Jarry remaining chemicals through baseline risk assessment.
RECEPTOR? <»'
TV*
^ List alt potential ecological receptors and receptor groups.
'Determine if complete exposure pathways exist for each source
^medium of concern.
Eliminate receptors/receptor groups if all relevant exposure pathways
for each medium of concern are incomplete,
• Carry remaining receptors through baseline risk assessment,
NOTE: Under the summary presented in risk characterization alt contamiants
and receptors must be presented along with rationale for eliminations made
during screening.
22
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EPA Region 10
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ecological screening process.
This step should focus the risk assessment on those contaminants that mayjof e significant
threats to the ecosystem. Figure 5-1 depicts where this step fits into thi greater ecological risk
assessment process. The risk-based screening will indicate whether or not there exist any potential
threats to ecological components at the site. Contaminants fitmd at col&^nfratiQns not indicativ
of significant threat to the ecosystem should be dropped from the^subse
assessment process, but should be retained for risk characterization. jJnTthe riskv
pack of] risk such contaminants present and the uncertainties related to these coallu'siojn« should
be documented, «-Vl - ^
The first phase of the screening revolves around potential Exposure pathways and transport
mechanisms identified earlier in the Rl. All potential -pathways ict€njifiedvshould be discussed:
incomplete pathways should be documented as^uch;; pathways which may exist, but are not yet
confirmed, should be listed as such, with specific detai| regarding the- unconfirmed points on the
pathway; and, complete pathways should'fee listed,, detaiiir^eaWstep of the pathway and how it
was confirmed.. The second stage of the screening level retieslbn comparisons and calculations.
Site concentrations must be mea|yr^d and^foxicity values for corresponding contaminants
determined. Ecological toxicityJ||pfes may,.^e found Jo1 the literature as well as many of the
references listed in text box 2-iy For the^mlny contaminants for which ecological risk-based
"%. S" "a^s-r'. ? 4^
concentrations, are not avsiiaiHei, toxicity referenc^Jvalues must be determined and subsequent
hazard calcujafofis exeoit^c|^rv> v"tesrsA
The nsMaased: concentrations and toxicity reference values will then be used for comparison
with site conceitftetiORS^The nsk-based numbers calculated for the screening process should be
conservative-and wftt b6, modified during the subsequent steps as more site-specific and less
uncertairfparameter datarefiarae^h/ailable. Section 5.7.1.3 outlines toxicity calculations to be used
in risj^ased screening <3pliRelated contaminants.
jjjjjf
A table preseni^ site-related contaminants, site contaminant concentrations and toxicity
^accompanifjifiy a site map indicating sampling sites, should be included in the screening
able to the RPM. Additional site maps presenting spatial distribution of particular
"the site should be provided only if they further elucidate site conditions.
At the conclusion of the screening stage of the risk assessment, the results should be
submitted to the remedial project manager. A summary of decision points and corresponding
deliverables is located in table 3-1. The results submitted must include a list of all contaminants
23
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
present at the site. A table should be provided, giving the following information for each contaminant
in all corresponding media:
the contaminant,
the maximum concentration.found in each medtup;
• whether there are any ecological receptors with a corrapie'te exposure jpathway |o this
»* sw» yff ,#
contaminant in each environmental medium (Hili ma^also be covered A#ii|pM!ie text.),
v v" *"f ^\
-\. "-&&.
• the screening value used to evaluate the gotentfaf tmard(s) associated with the
contaminant",
the hazard quotient,
the contaminant background level in eacft'med^ $ -^
ecological risk assessment, or at feist the frequency of exceedences.
is pmsenied, as tabfe 3^1^I;A site map indicating sampling sites should
accompany t*e table.. Addfi^kslt^ipaps showing the spatial distribution of particular contaminants
of concern at tfie sU^-should b€ j»^lded only if they further elucidate site conditions. Figure 3-1,
shows a sampfe disltrib^hiqn map.i
The screening level may be a TRV derived from a NOAEL or related value or it may be an RBC from a
source approved by the RPM during Phase I of the RI/FS process. At this time very few RBCs exist for
ecological risk comparisons; it is important to consult the RPM before choosing to use any values
encountered.
24
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Contaminants
Table 3-1
Sample Summary Table for Contaminants of Concern
(after initial risk-based screening)
Maximum Risk-
Detected Based
Levels Cones
(ppb) (ppb)
Frequency^
Samp
Exceeding
Screening ^Background
Values (ppb)
Frequency of
N Samples/
Background
05 Values
Usr"\^
1,1,2,2-
etrachloroeihane
Bis(2-
ethylhexyl)phthatate^ *
richloroetheflfc ^ " >
hloroform
W
Dibrdchochloromethane
P
25
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
US2-9
0
crinMs
HOaUNSPONBA
MORMON SPRWQB
MORMON fflRMC
Figure 3-1 Site Map Depicting Sampling Locations
26
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EPA Region 10
DRAFT Supplemental RAGS
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Background data may be employed in the screening process to determine 'which site-related
contaminants, particularly inorganics, exist on site at concentrations elevated ahoye* surrounding
natural background levels. Planning for background sampling should have'sccurred at early in the
Rl so that time is not wasted waiting for background data to be collecteSt/Ttte collection and use
of soil background data for ecological risk assessments isjficussed irVHirther detail in an issus
paper in Appendix C; other relevant references are listed wifh that paper arxlb section 7. /
As can be seen from the discussion above, the coniatiwiant portion of the screening process
is somewhat prescribed; the screening process for receptors, although it can become somewhat
complex, is not so established. Receptor screening should simply identify potential receptors and
receptor groups on site. The first step is to catalog the plants a net wildlife von the site. The second,
is to determine which of these organisms may be exposed to the dj&^inants, via any exposure
pathway(s), from the site. -
Such a screening may be organized by species Of fartCtiSrtal groups or even by specific
populations. It should be through and well documented, allowing for tracking of those organisms
determined notio be potential receptofslsis well as?those whidhrare. Assistance from local plant and
wildlife experts may help to identify Jess common receptors: The end result of this process should
"•*:•«$ «•¥•:*&, ••••••••••-'••:?'
be a compilation of potential receptors, species or groups judged not to be potential receptors and
justification for each detenro'rtaiibn. This may be'presented in the following described interim
deliverable;:-:it will aid fa development of ihe conceptual site model as well as in the risk
characterizat10n'-s«m/riary justifying -inclusion or exclusion of particular organisms in the more
detailed analyses of the risk assessment.
At the conclusion i?f lite, ecological risk-based screening, an interim deliverable should be
^ .^jvy ^ v*3#ik
submitted'to the remedial ftra&surianager (RPM). Such a deliverable should list all contaminants
* ffi '^^SBS&Ssiis?'
of qQpfeem present at ^^^p, site concentrations of these contaminants, the toxicity and/or
bajcground data used in Jfre screening, the source of this data and the number of site concentration
exceedances above thjfchosen screening value. For contaminants found to be elevated only in
: areas (hot^jbts), a map identifying these areas should be included. A list of potential
j those with complete exposure pathways to contaminants should also be
presented,.. Relevant concentration-based distributional maps which illustrate fate and transport
and/bnexposure pathways for selected contaminants may also be included.
3.5 Revised Conceptual Site Model/Exposure Pathways
27
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EPA Region 10
DRAFT Supplemental RAGS
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The conceptual site model and exposure scenarios and pathways planned for the risk
assessment should be revisited at this stage. Depending on the amount of information previously
available and new information obtained from sampling data, a revised co^ceptuajple model and
presentation of exposure scenarios may be needed. If only general ide^wef^'presented at the
scoping stage, more specifics should be presented. If new infojEjpation^iisiss significant changes,
Bvfssad information Q$
Ss~V *x 4s"
revisions should be submitted. If additional phases of sampjinj are plan
exposure should be considered in the new work plans.
28
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
ments (section 4 and 5) may be
4.0 BASELINE HUMAN HEALTH RISK ASSESSMENT
4.1 Scheduling of the Baseline Risk Assessment
The baseline human health and ecological risk
submitted as part of the Rl report, or as separate docum
4.2 Exposure Assessment
The degree of "protectiveness" or "conservatism" that Wilt be used in exposure assessment
for Superfund risk assessments has been the subject of considerable discussion. In order to have
consistency in risk assessments nationwide, Superfund program guldaiWs^.descibes in some detail
the approach that will be used. RAGS HHEM Par^A"C£PA 1989d>, Clteptere, provides guidance
on development of reasonable maximum exposurfe,%{f^ME) scenarios, andtlstdndard Default Exposure
Factors (EPA 1991h) gives specific exposurejpaclors, fc$«^mpte,drinking water ingestion rate, that
should be used as defaults for all sites.^-These feifctorsxwiH $eldsmri be subject to modification.
However, certain aspects of the exposure assessment, particularly quantification of absorption of
chemicals from soil and estimation?'<#» exposure point cjiicentrations using modeling or other
tfipy&J* _ f .•&>$$
predictive approaches, have not|peen "standardizedjfind will require site-specific data and
judgement. The use of simplified, pathway of release or exposure, subsequent calculations are
«y, _ •. s r, «sio fX*tti $*'
often subject la refinement in thft.fteJxl Iteration, if necessary. For example, if conservative "worst-
calculations show risks
case" assumpfipns fibg^4 releasfs^fgniammants from soil to air are used in human exposure
calculations,,and result&^sllpw that risfes are well below risk-based goals and levels of regulatory
,$jjft&' " *ifif)tf;f*i'fjpXyk v •• "
concern^pore compteikieiejldfetailed models would not be necessary. If results of the same
"fj«? •. ww.Avfe*X- tf t*..
, additional effort and collection of site-specific data is justified.
Selection of Exposure Scenarios
W- -> To insureM&t appropriate data collection is planned, the conceptual site model and the
embsur« stefioids and pathways should be presented as early in the RI/FS process as possible.
~£j / ^^7^.',^^ r
Exposure ..scenarios are revised as necessary as more information becomes available. Issues
affecting selection of exposure scenarios and pathways are discussed below.
The baseline risk assessment will consider risks under both current and future land uses.
29
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
The land use scenarios most commonly evaluated in Superfund risk assessments are residential and
industrial land use. However, scenarios in addition to residential and industrial use can be
developed in consideration of the location, size, and current and potential uses of thjS affected area.
•% -^^
Scenarios may include fishing, agriculture, recreational or other occasional activities;' as appropriate.
Evaluation of multiple scenarios (including residential, indust|||, and rftcroati^al land use) will be
appropriate for many sites.
Region 10 recommends that a residential land ttse scenagp%e evai6lted as "a potential
*& "'"^ *£*"-^i ^ -y
future use in the baseline risk assessment for most Superfimd sites. The reasons f6Y making the
ss % \ s 'SVA
general recommendation that residential land use should be evaluated include the following:
w •". ..."•Sty-™ j.
1) Predicting the likelihood of future changes in land use 6a« b€runcertain. For example,
anticipating which military bases may face closure in the future It-fceyond the scope of a
Superfund risk assessment; the residential scenario shouldibfc syaluated as a "what if
question.
be implemented to prevent
thia^'scenario in the baseline risk
2) For sites where institutional controJFbr acce
future residential land use, evajlation ofpthe res
assessment provides justificatipjr for this,iype of<
3) The residential scenario usupyprovid^the most!pbnservative estimate of exposures at a
site, in other words the highest estimate £f risk, rlf^results were low risks, this would provide
the most comfortable basis for a no-;acll6Oedsion, and confidence that Superfund could
,
Including reMcteaitiafcLand use
sS!iasss».iasjNaN\ 'ss
up for residentfai us«.;;;.l^€sentati
in the baseline riskissd&liftent for a
^sSS^SKw^-^'V^-^P**.
various riskrftanagemeni;<5rfloTts. Du
assessment does not dictate that the site will be cleaned
of quantitative evaluation for more than one scenario
ives decision-makers more information when considering
g the FS process, managers will determine which land use
eciding whether remedial action is warranted, and the basis for
assumptons will be the Sasli
selection of final remed.
However, at sojpe sites or operable units the RPM may determine that it is not appropriate
jate residentialrand use in the risk assessment. For specific sites where the RPM believes
Hal use is highly unlikely, this scenario may be given less effort in the risk
may be eliminated. If evaluation of a residential scenario for such a site would
necessitate additional sample collection, the benefits of the information should be weighed against
the costs of collecting it before proceeding. The level of effort devoted to evaluating residential land
use may be limited through the use of pre-existing sample data, standard exposure assumptions,
and "screening" pathways.
30
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
4.2.2 Select Exposure Pathways
Within each exposure scenario, specific pathways that will be evaluatedjplTbe selected
based on site-specific characteristics and on general considerations outlinft|el(rfand in table 4-1.
Soil and water ingestion pathways should always be consigned, contaminant
concentrations to screening concentrations based on themllthwavs!'ii||l||i|5sed in sectior
above, multiple pathway exposures should be evalua
"contaminant of concern" remaining to be carried throuj
31
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Contaminated
Medium
Exposure Scenario
Potential Exposure
Pathway
Evaluate in Risk
Screening?
Evaluate in Baseline
Risk Assessment?
Groundwater
Residential use as
potable water
Ingestion of water
Inhalation of volatiles
Dermal contact with
water
Yes
>, if volatiles present
Yes, for organic
contaminants of A
concern ^H*
Industrial use as
potable water
Ingestion of water
Inhalation of volatiles \
Dermal contact with
water
cisnn
Site-specific decision
Surface water and
sediment
Residential or industrial
use as potable water
See
Groundwater
Recreational or
subsistence fishing
Consumption of T i
Recreational or
trespasser
in of water'?'
tf
contact with
IngestioSiw sediment
Site-specific decision
Soil
particulate/volatiles
from soil
Yes
Consumption of
produce, meat, milk
SoH ingestion
Dermal contact with soil
Inhalation of
partteulate/volatiles
from soil
Yes
Yes, for contaminants
of concern
Yes, for contaminants
of concern
Site-specific decision
Yes
Yes, for organic
contaminants of
concern
Yes, for contaminants
of concern
' In general, these pathways will not be included in a simplified screening, but they may be considered if site-specific screening criteria
are developed.
Figure 4-1 General Approach for Selection of Exposure Pathways
32
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
4.2.2.1 Pathways of Exposure to Soil
For contaminated soil, incidental ingestion should always be
exposure through dermal contact with soil requires cheraj^il-spe
Absorption data for organics should be sought in the Guh
(EPA 1991b). If no absorption data for contaminants
available, dermal exposure should be addressed qualit
absorption of inorganics from soil is not available. Dermal
effects at the skin surface, for example certain metals, can
can be obtained. Inhalation of volatile and particulate con
be evaluated, again usually limiting the evaluation t
screening stage. Evaluation of air pathways can b§
contaminated soil is left in place, with direct
pathways of exposure to contaminants in soil
be evaluated less frequently. Site charaftistics wJ
pathways important would be:
Assessment of
Srption information.
i as
:itative
ith contaminantlpat pve toxic
'ftt§jS&K-v
.ted quantitatively if information
ased from soil to air should
:em identified at the
ularly impl||||:|||;-sites where waste or
throulfiiBcess restrictions. Other
?
animal food products, will
consideration of food chain
m
:bntarrii
slant
• current residential site
A
• large areas of contaminated soil
linantsknovynto be taken ufHrto plants or animals at potentially significant levels,
lie cadrrilmMdPCBs.
^v?^
Decisions to incffcu
Region 10 riski
agricultural area
jphain paihwayis m should be made in consultation with the RPM and the
"
4.2.2.
Ext
Groundwater
If contaminatedjiotable water is present, or contaminants may potentially affect potable
exposure thrapgh ingestion of water, and through inhalation of volatiles released from
! water^liPfnould be evaluated. Dermal contact during bathing should be evaluated for
fants of concern using permeability coefficient data available in the Dermal
vd//>7es(EPA199Tb).
4.2.2.3 Pathways of Exposure to Surface Water and Sediment
33
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
For contaminated surface water and sediment, potential for human exposure varies greatly
depending on the size and location of the water bodies. For sites that have small water bodies or
that are in remote locations, exposure pathways can be limited to incidental ingesion for a child
playing or a "trespasser." If these exposures appear to be of concern, howevef^or for some sites
with potential for recreational use, dermal contact should also be JncYu -S'&v, % "¥*^*"*\ ^--'\.
consumption pathways will be an important consideration aCsites where lafg$ water bodies an?
^" . «s3>s»L% *"«-«•" "x~
affected by contamination. /
•&
4.2.3 Calculating Exposure Point Concentration from Sampffng Data
4.2.3.1 Calculating the "RME" Concentration y^ - ,-T,-,
» %s •..-.%> IA ••% ^--XXv>
HHEM Section 6.4.1 states that where results from several Sfi61|>tes will be combined to
estimate exposure point concentration, the appropdate Calculation is Kiifnety-five percent upper
confidence limit (95% UCL) on the arithmetic average (e#ee£t wheatfie 95% UCL exceeds the
"• V. ^ \ % •• -.X-.s«%1A % s<>^ ^
maximum) of concentrations that would J)e contacted by,^e^'1^[E" individual. Averaging and
statistical treatment of data is correctOfily for samples thaf v&eire collected with an appropriate
random or systematic sampling desi&h. Further guidance" on developing the "RME" exposure
concentration is available in EPA gtjPcJance (EPA X 199J/
4.2.3.2 Grotipipg Samples^ I ^'
data to evaluate exposures must take into account spatial distribution of
contaminants, hwman activity patterns* aftd potential fate and transport. Section 6.5.1 of RAGS
HHEM summarizes 5Ome exposure pathways issues and includes the following guidance:
,/The manner fo ^Ytotefc*' the data are summarized depends upon the site
characteristics a^dj the, pathways being evaluated. It may be necessary to divide
chemical data frorfi arparticular medium into subgroups based on the location of
sample points artdfthe potential exposure pathways. In other instances, as when the
sampling poin3*fs an exposure point (e.g., when the sample is from an existing
.drinking w|||Pwell) it may not be appropriate to group samples at all, but may be
latest apgllpnate to treat the sample data separately when estimating intakes.
If rrrciettfeaH one source exists at a site, it may be appropriate to evaluate exposures for a separate
"RME" individual for each source area, because the soil or water at one source area may present
distinct exposures and risks that are not present elsewhere on site. However, for a site with multiple
source areas it is also possible that release of contaminants to air or water from various sources will
34
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
affect the same down-wind or down-gradient receptor, so the cumulative exposure should also be
evaluated. It is useful to identify the location of cohtaminant concentrations of each contaminant in
soil and water on a map to evaluate whether risks from different contaminants do ogilViot coincide
in location. Needs.of decision-makers will be a factor in determining wJfbberJPivaluate source
areas together or separately.
that
Groundwater samples from a single well locatiqfclSver time
represent the 95% UCL average concentration that would ^contacted by
location. In practice, a single well point usually does not yla enough data to perrni|pcifation of
5^' * A '''•fy3j$&'
the 95% UCL. A simple average has been used in some ris^.assessments. Future exposure point
concentrations estimated by modeling may be used in the risk assessment if the RPM and technical
staff determine that modeling is appropriate. -^ ^W^S,
Surface soil sample data should be usedMrepresent the 95% UCL average concentration
*-3sp%$i?"**?'"""""*-Z\ ,*•
for an area the size of a yard for residential use scenafk>$. The reassessment should identify
whether the concentrations used for calculations are typiicaldf large areas of the site, or represent
a "hot spot." If contaminant concentrations vary significantly over the°site area, it may be appropriate
to calculate several different exposum point concentrations, using a subset of samples for each.
,$&&& ,'*3? *&
For sites where future construction,^ residences is possible, the exposure assessment should
consider concentration at the current surfaceTand aiso that construction activities could result in
';'^ •. S$- •. -"*V «\BT •• 51-ji ^Sv
excavation of $oil, and distribution of this seal at the surface. Exposure calculations would use the
y^^-Sf^ ™, -.«*>% ^ --.^B-I %\;-
95% UCL average of samples to an appropriate depth for this case.
------^-
4.2.3.3.
Th^enUre issue of grafting samples can be avoided by using "risk maps" to present reults...
[To be $id in following'^caiswttalton to OEA HH risk assessors.]
ifr fira^
4.
lest that exposures and risks from on-site sources be summed separately
iropogenic background in the risk assessment. Treatment of "background" in
will depend on ability to distinguish site-related contaminants from other
chemicals detected, and risk management issues.
4.2.3.5 Non-Detects
-------
EPA Region 10
DRAFT Supplemental RAGS
March 27, 1996
Where a specific contaminant has been detected at some locations on a site, but not others,
or has been detected in past sampling events but not in current samples, the contaminant should
.•:•:&••_•
be assumed to be present in the "non-detect" sample at one-half the sample detection limit. This
approach is specified in section 5.3.3 of HHEM. However, judgement $houlcf'also be used in
«-5> ''>,: ?
evaluating of non-detects. First, it is important to consider spatigri distribution of Contaminants at the
' ™^ • ..*« , i^s
approaches or models for development of predicted exjpasure point concentrations are mentioned
in the directive, their use is not fceing mandfi^iidL^Jfif addition to the cited references, continue to
consult national guidance andi tfie publisftedlfterature for the most appropriate methods for
predicting" 10"* and
moleculaypight <200.
^^^S^^^ndoor air concentrations by assuming that they will be related to concentration
water supply according to a coefficient of 0.5 l/m3 (EPA 1991c).
4.2.5 Contact Rate, Exposure Frequency and Duration
36
-------
EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Table 4-1 Sources of Exposure Factors for Superfund Risk Assessments
Exposure Pathway
Exposure Faffors*
Ingestion of Water
Indoor Inhalation of Volatiles
Dermal Contact with Water
Soil Ingestion
Dermal Contact with Soil
Inhalation of Particulate/Volatiles from Soil
Consumption of Produce, Meat, Milk
Consumption of Fish/Seafood
*WS8&£8!!*f
Region 10
Region 10
Region 10
Re-specific
Site specific
4.2.5.1 L/se of Stendanrf Default Ex/a
Fact
The supplemental guidagJIPdocum
1991h) provides specific ex^uUffactors
Assessm^|ll;A draft
1995).
ntitledjpindard Default Exposure Factors, (EPA
e used for Superfund Human Health Risk
he Exp^jjjiaclors Handbook has also been released (EPA
factors (SDEF) are summarized on page 15 of the directive
lues in the directive supercede the RME values presented
of Work RI/FS Risk Assessment.
he SDEF supplemental guidance,
'...the exposure fjp&Wpresented in this document are generally considered most
appropriate and fjPuld be used in baseline risk assessments unless alternate or site-
specific valuesjpn be clearly justified by supporting data.
r
on, soil ingestion, and inhalation defaults will apply to virtually all sites. The
fThe Standard Default Exposure Factors, (EPA 1991 h) compiled by the Superfund program, is the source for RME exposure
factors for Superfund risk assessments. For "average" exposure factors, and for pathways not addressed in the SDEF guidance, Region
10 has provided recommended values, mostly selected from the Exposure Factors Handbook (EPA 1995b) or Dermal Exposure
Guidelines (EPA 19915). For convenient reference, exposure factors from both SDEF and Region 10 are presented together in Appendix
37
-------
EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
need to evaluate consumption of homegrown produce, meat and milk, and consumption of locally
caught fish will be determined according to characteristics of each site. For these food chain
pathways, it is also expected that site-specific exposure values will usually be prefera§fe to defaults.
Assessment of dermal exposures is not discussed in the directive. Tl%"Gufdance on Dermal
Exposure Assessment" being developed by ORO Exposure AssessraMu will address this
pathway.
4.2.5.2 Region 10 Default Exposure Factors
Exposure factors for the dermal pathway, which is no$ a&lpessed in the SDEF.Tor the RME,
and for all pathways for average exposures, are presented !R Appendix B, table B-1. Although
V" -. -. -A f. f. HW ^.^
regulatory decisions for Superfund sites will be based on risks at RMKexpOSures, average exposure
-'v-.*., ••"••••
factors are presented here for two purposes. Average exposure factOfS^W||l>6i'Used for comparison
in uncertainty analysis. Also, average exposures^wi be insNided in som$ypvlE scenarios, as stated
in RAGS HHEM on page 6-47: ^ &
iss pathways, it may be
estimate of more typical
ited, age-specific intake factors and body weights
.presented in the Exposure Factors Handbook
exp^M|i:J||ctors foPtnVdermal pathway presented in Appendix B are
ion lb:1^eidsBrlf the Dermal Exposure Guidelines (EPA 1991b).
To calculate an exposure that is a feasonabjft^maxir
necessary to combine the RMf for one g&thway
exposure for another path\
When subchronic or acute exposures are
for children s$CMd be used.. ^g6-specific fai
(EPA 1
recommen
4.3
.ME
assessment Should be conducted as described in chapter 7 of RAGS HHEM.
lues
sources for toxicity information is as follows:
Id Risk Information System (IRIS; EPA 1995d). On-line database. IRIS is the
EPA source for toxicity information. It provides RfD's and carcinogen slope
ictors that have been reviewed and verified by agency-wide work groups. Supporting
discussion and references also appear in each chemical file. IRIS User Support (513-
569-7254) can provide information about how to access IRIS. IRIS is also available on
PC-compatible diskettes from NTIS.
38
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Health Effects Assessment Summary Tables (HEAST; EPA 1995c). (OSWER Directive
No. 9200.6-303. NTIS No. P890-921100.) Prepared by the Environmental Criteria and
Assessment Office for the Office of Emergency and Remedial Response^The HEAST
tables provide a summary of all currently available toxicity factors developed by NCEA,
and a bibliography of Health Effects Assessments and rel^f&d dements. These
documents contain supporting information for toxj||y values developed by EPA NCEA.
Additional chemicals that do not appear in IRISJi^1ncluded;lo:H^ST. The HEA6
tables are revised quarterly. Effective in the seo&pquarter, 1§pH:f^o^|tpxicity fac
that appear in IRIS will no longer appear in HgAST.
Toxicity reference values developed by, on;irO^stfltation with, the
Technical Support Center at the National Center tot Environmental Assessment (NCEA)
in Cincinnatti, (513) 569-7300. Region 10 risk asse|$rnent staff should always be
contacted before calling NCEA.
ATSDR minimal risk levels (MRLs). These values are developed (ising an approach that
is consistent with reference dosejmelhodology. These* are available for acute,
intermediate, and chronic exposure dilations, £n
-------
EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
supporting the RfDs will be important. In addition to sources listed in 4.2.1 above, the published
literature can also be consulted and referenced for toxicity profile information.
4.4 Risk Characterization and Uncertainty Analysis
Combining exposure and toxicity data to characterize Hsks is described jn RAGS HHEM
. k *" '-•^-•-•-•-•-•-•-•-••'•* -•-•:.:<:••
.
chapter 8. Uncertainty analysis is discussed in RAGS HHEM sectio
frequently occurring questions/issues are addressed below.
5i8.4.1. Some
4.4.1 Exposure Duration for Noncarcinogenic Soil Cotftamtnarrts
[To be discussed with Region 10 OEA HH nsk aSsessorsL
4.4.2 Risk Characterization Using RfCs and
Toxicity reference values for rnh
tion pathways .are
concentrations (RfCs). RfC units are cohcentrat&jh in air,
vided by EPA as reference
The RfC can be used in risk
characterization using a simple comparison; thfrmost straight-forward approach is to evaluate a
if$t^ $
-------
EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Qualitative discussion of uncertainties is expected for all risk assessments submitted to
Region 10. Uncertainties in the quantitative risk assessment process should be recognized, as
discussed in the agency guidelines. The RfD Background Documenf (EPA ,|^d) provides
perspective on interpreting reference doses, including the following:
...the RfD is an estimate (with uncertainty spanning
of a daily exposure to the human population (inck
likely to be without an appreciable risk
lifetime...However, it should not be categorically i
RfD are "acceptable" (or will be risk-free) and thai
"unacceptable" (or will result in adverse effects)
is an
[g sensitivj
deleterio,
icludedpat all
in excess of th
Id).
Slope factors for carcinogens are derived by the EEpPus
procedure." The Guidelines for Carcinogen Risk Assessment (1
; the "linearized multistage
Acknowledge that:
...the linearized multistage procedure leadsio apt
is consistent with some proposed mechanisms^
of the risk is unknown, and may beers low asze
However, because the risk assessmentJpr a Superfund site jflntended to support decision making
within a defined regulatory context, tH^l^k asses^br should Jlarly distinguish uncertainties inherent
in the risk assessment process (i.e. fcixicity values base
ible uppelpit to the risk that
pgenjsts... The true value
experiments!, or common to>Superfund
t\ y^ns^s , --?••
exposure parameters, lackofdStaon dermat a\
#•"• •
iscus
low-dose extrapolation from high-dose
(i.e. assumptions in standard default
V '*•'
irpfion from soil) from uncertainties specific to the
focus on site-specific uncertainties. These might include data
??•.%*. 'S ••% • '*•"'*** ff-y&tHf
gaps in site:%amp|f|9^,uncertaln^,N'modeling for fate and transport, uncertainty in assumptions
about future lahdl^^ iaiKi data gaps for toxicity or absorption information. After risks at RME are
calculated forr.*a<^''|la^vaV, it is possible to identify which chemicals, scenarios and exposure
routes present risks olf/^ftjWMagnitude. Discussion of uncertainty should focus on the more
4M&2 Quantitative U$£rtainty Analysis
analysis of uncertainty in exposure assessment should be presented. The
y Region 10 is evaluation of impact of average compared to RME values for
' .
and exposure point concentrations for pathways contributing most of the risk. If
modeling has been used to develop exposure point concentrations, sensitivity analysis for model
input assumptions is also appropriate. Because decisions at Superfund sites are based on risks to
the reasonably maximally exposed individual, as specified in the NCR (EPA 1990d) and as defined
41
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
by the associated guidance (RAGS HHEM, SDEF), more sophisticated approaches to quantitative
uncertainty analysis will usually not be used.
i
?'
4.4.4 Summary and Conclusions s\
- 4, ~-/ -
The risk assessor and reviewer should devote some care to pfQVktJngf an effective and
concise summary of site risks, because this section will "^|ahd alone" fgr'sbr&e^persons interested
in the site who may read the summary but not the rest of the nsk assessment?'*
-. •. y % j v.j, % ^ •.
Risk assessments containing unqualified statement^; $i|cft.as: "Risk from chemical XYZ in
drinking water are unacceptable..." and "Risks from exgosSliiWjSQjl are insignificant..." have
sometimes been submitted to Region 10. Writers of Superfund ilsfcl&S&sments should avoid the
use of terms such as "significant," "unacceptable/ cr^'not of roaeeiiriB interpreting results,
particularly if the criteria for significance or concern are not clearly defined ifrthe report. These terms
•••• % '^Aj. «J^
imply conclusions about whether remediation will be undertaken at the site; risk management should
" t v A \ 5 J; i %tv. rtss it"
be discussed in the Feasibility Study, not in. fiie baseline risk assessflnw&nt. Preferred language would
be something like, "Risk from chemical XYZ in drinkgtg water w» calculated to be 9 x 10^. For soil,
total risk from all contaminants was ie$$ than 10*." The risk' assessment may cite the NCP (EPA
1990d; see page 8848) or Role oft^Baselin&^Risk meitM (EPA 1991e), and quote the language
on the "risk range" used in Superfthd, if thills acceplajble to the RPM.
42
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
5.0 BASELINE ECOLOGICAL RISK ASSESSMENT
5.1 Introduction
The purpose of this ecological risk assessment chapjer is to pfpVKfe.guidance to regional
ecological risk assessors on how to conduct an effective risK%ssessmentr%B''ct»a|)ter also
as a supplement to the national guidance to clarify and stkeamline thejpcotogical risk assessr
process for Region 10 Superfund sites.
serve
Ecological Risk Assessment is a process that evalulls tieMelihood that adverse ecological
AX $* -j&
effects may occur or are occurring as a result of exposure^Ort&^naore stressors (EPA 1992a).
Ecological risk assessment is an integral part of the RSmediaf Investigation and Feasibility Study
(RI/FS). The three components of the Remedial Investigation (Rl) procesVarfe: (1) characterization
of the nature and extent of contamination; (2), ecologicalrtek assessment; (3) human health risk
«. ^ - •» ^ •• -"• %:>-?• v
present at the site, as well as the distribution and concentration of Ihe^CTiemicals. The ecological and
human health risk assessments determiijif the potential for averse effects to the environment and
^S&SSS? -"" *••• *•
human health, respectively. This
rfoc
The current EPA appcoaqpi to ecologfca^risk;«|iessments for Superfund are based on the
human heatft^jsk assesSfdea^format, bul'ltckJffieci' for the increased complexity of organisms
encountered aad their intefdcidi'iljin the ecosystem. The purpose of ecological risk assessments
3f&\' '^ "' w&s&i&^^lfc.
may vary with!H';iprogranis, but they iaeppalty serve to provide risk managers with an estimate of the
*5>*^ ^ "^'Zixz^it
extent and mago««M|e of Adverse effea$#n the ecosystem of concern.
ERT'Region t
procesSFand tools use
docqpent borrows hea
,,%$
Gwj&nce for Superfund^
iview of Ecology
risk a
assessmer
lental guidance is a region-specific document that outlines the
fducting ecological risk assessments at Superfund sites. This
m the EPA headquarters national Ecological Risk Assessment
A 1994a), the Framework for Ecological Risk Assessment (EPA 1992a),
"Assessment Case Studies (EPA 1993b & 1994c) and other EPA regional
ment documents. Figure 5-1 outlines the major steps of the ecological risk
s. Text Box 5-1 summarizes the pertinent decision points and associated steps;
i/s these decision points in relation to corresponding deliverables.
43
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Screening
Step 1: Problem Formulation & Ecological Effects Evaluation
Step 2: Exposure Estimates & Site Characterization
Potential Ecological Threat
Low Likelihood of Ecological Threat
Step 3: Problem Formulation
• Selection of Assessment Endpoints
• Development of Testable Hypothesis
Step 4: Development of Conceptual Site Model
• Selection of Measurement Endpoints
Selection of Study Design
Decision Point #3
Step 5: Site Assessment
• Confirmation of Ecological Sampling & Analysis Plan
• Verification of Exposure Pathways
Decision Point #4
Step 6: Reid Investigation
Site Investigation Consistent with Work Plan
Step 7
Risk Characterization
Data Analysis
Uncertainty Analysis
T
StepS
Risk Management
Decision Point #5
Signing the Record of Decision (ROD)
Figure 5-1 The Ecological Risk Assessment Process
44
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
This chapter is intended as a supplement to the upcoming EPA headquarters Ecological Risk
Assessment Guidance for regional site managers, risk assessors and others involvelln ecological
risk assessments. It focuses on issues related to Superfund sites in Region, 1 ^Furthermore, this
document does not determine the scale of the ecological risX^ssessn^ior^ve specific details
about investigative techniques which may be used in the eco^lftcal risk
tools (e.g., toxicity bioassays) and examples (site-specjfic case
assessors and site managers to make sound decisions which are,i(ec'hnically
effective.
5.1.1 Chapter Objective
This chapter is organized according to the EPvA headquarters* pttflirte of major steps in the
Superfund ecological risk assessment (EPA 19940£y While the baseline ecological risk assessment
report is the final deliverable for the risk assessment, a set"$?• - .^r.-' ~&s- '
is an ad/noc group comptwfcawmembers invited to serve by the RPM; Region 10 BTAGs are
spediS to given sites J|p|pijects. A BTAG usually consists of EPA staff specializing in
enili&nmental scien<^sjfecology and ecotoxicology as well as individuals representing related
lizations such asjtjne U.S. Fish and Wildlife Service, the National Oceanic and Atmospheric
stration and jelled state agencies (e.g., DOE). These members function in an advisory and
assist the RPM with the risk asessment process. The RPM may consult with
members as well as the BTAG team, if one has been established.
Communication between the contractor and the BTAG will facilitate the ecological risk assessment
process and will help generate some consistency among all parties involved.
5.1.3 Technical Issues
45
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
5.1.3.1 The "Tool Box"
The "Tool Box," Appendix C, delineates specific technical issues relevant to the risk
assessment process. One of the ecological issues addressed in the "Tool Ipox1' is jlie determination
and application of background concentrations of contaminantsjn soil ajtjk|terfond sites. Appendix
C will be an evolving section of the guidance which will addrfc&S various dsjk assessment technical
issues as the need arises and information becomes available. AddidoYis to m$ Section wi&be
W &> •• #&£ ' -y--. A. ,#f'
released intermittently in the form of the new Region wRisk R&port newsletter -SiRcer issues
described in. the "Tool Box" are not the only ones encountered in'the ecological risk Assessment
process. Please refer to the following EPA publications forattJOfe'eomprehensive list of issues and
additional information: Eco Updates, BTAG Forum and Ri$k A$$$$$rnent Forum Newsletters.
5.1.3.2 Site-Specific Case Studies
Site-Specific Case Studies provide "real
s" A^'
have been conducted. These case-studies;:are examples
$rf how ecological nsk assessments
risk assessments that have
fionuclides in the Columbia River
been completed. The following are some examples;. Effects
System - A Historic Assessment (EPA/6&0/R-94/003); Commencement Bay Tidelands Assessment
(EPA/630/R-94/003); and The EffUfts of AGfti Deposition on Aquatic Ecosystems: A Regional
Problem (EPA/6307R-94/003}< For additional else ^Studies examples, please refer to Appendix D,
and to the EPA publication!: A Review o£* Bxjfagical Assessment case studies from a Risk
Assessment P&f&pective, VoJuftie ft (EPA/630/R-94/003). Similar to Appendix C, Appendix D will
be expanded O^drt Ittermittentt^lStS Via special releases of the Region 10 Risk Report.
46
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Text Box 5-1 Ecological Risk Assessment
Steps and Decision Points
Preliminaiy Problem Formulation and Ecological Effects
Evaluation.
Preliminary Exposure Estimates and Risk Calculation
(DECISION POINT # 1).
Problem Formulation: Selection of Assessment Endpointe?
Development of Testable Hypothesis
(DECISION POINT #2),
Development of Conceptual Model, Selection of Measurement
Endpoints and Study Design
(DECISION POINT #3),
Site Assessments: Confirmation of EcologU^Sam
Analysis Plan and Verification of Exposure Pathwa
(DECISION POINT #4).
Reid Investigations: Site Investig
with Workplan.
onsisti
Risk Characterization.
Risy«itement (D|CJS|0^plNT # 5}i
5.1.4 Scheduling the
Baseline Risk Assessment
, health
asessments
and the baseline'nif^sessment Itself occurs within Phase III
v.<^.'-'«'Ax.j^wk?-«v fff <%<|,> Vtf&t ^f~4Sf
phases are further expte&idd Within section 1.1 of this document.
Asindicated in section
4. V *oiJfcit$& document, t
s v.v*i -S . "•. »Y
baseline
ilogical
be submitted ^: part of
Rl report or as separate
This will be
by the RPM with
feom the contractor
corJdKlcting the assessment, as
w$lfas advice from the STAG
-"Team. A time line which
addresses the deliverables
associated with each decision
point should be established
with the RPM at the beginning
of the risk assessment. The
first three of these interim
deliverables will be related to
Phase II of the RI/FS process;
of the risk assessment. These
47
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Table 5-1 Decisions Points and Corresponding Deliverables
Section which concludes
with Decision Points
Decision to be Made
, Deliverabfes
Screening
Determine whether or not 9,
significant ecological thn
may exist.
creening
Table
Map
OttofeFrelevant sfte
calculations
Problem Formulation
Agree on objective(a)iv^
testable hypotheses
selection of both assessment
and corresponding
measurement endpomts '
bjective(s)
le Hypotheses
i&pdcted ecological effects of
Eidbbyaiable
Problem Formulation
(with Conceptual Site Model)
Agree on exposure^
development
srte modei!^ the ^
assessmejF worjtp
samplinQjjiJa'nd ana
(SAPJ||pte investigation and
metEtola of dataJffalvsis.
He Model
Plan
Site Assessment
jlting fro
;;the field st
' or SAP
' final workplan and/or SAP
••' !«.
Risk Man
and initiate
Jons for the site
and the development of the
bf Decision (ROD).
Baseline Ecological Risk
Assessment with: Remedial
Action Objectives (RAOs)
and Risk Characterization
S.I.SijEhapter Organiz,
This chapterJpnapter 5) is organized in accordance with the EPA Ecological Risk
j/?f Gu/da^iJe for Superfund: Process for Designing and Conducting Ecological Risk
w
1994a) and with an ecological assessment overview presented in the EPA's
ecei^^pprihtermittent bulletin, ECO Update (EPA 1989b). The former document is based on
the EPA's Framework for Ecological Risk Assessment (EPA 1992a).
5.2 Screening
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Ecological risk assessment is an iterative process which mandates increasingly specific
levels of investigations as data are acquired. The screening process must be thorough in its scope,
but not overly detailed. Overly detailed screening can encourage limited areas ofjPcus; and this
step must provide a complete picture of all potential ecological concerr«^pre«#rit at the site. If
available information indicates the need for further investigations, such $$!J$$K conducted within
the following ecological risk assessment process.
The preliminary ecological risk assessment efforUftnvolve the"lfirst twov;sfef>s (stepS4^& 2)
of the ecological risk assessment process. These first tv«^$p&!^ often refenrecfi^'al'scfeening
steps as it is during these steps that the media, exposure pathwayl>receptors and contaminants on
'ii ^ %%^% -4 \t ^^
which the risk assessment will focus are selected and othefslare determined of lesser or no risk.
%..%% •."££ •. s -. * <
The components addressed within these two mitiahsteps are* UstetfHn text box 5-2. These
components are described in chapters 2 and 3 ancUhey..
are often begun before work on the basefete\.ri3jk
assessment is formally initiated.
5.3 Step 3: Problem Formulation
The problem formul
environmental attributes to be pi
data and analyses need
characteristics WJ{J be id
of a conceptual jsifesimodel.
The steps'-
interactive, depending
site model. Information
Ithough the
decWons, these data
the risk
identifies *
\ dSSK,
cted
mplisKllsjs^ These
the development
.. Text Bcfc 5-2 Steps Involved in
igical Risk Assessment
Screening
Preliminary Problem Formulation
Ecological Effects Evaluation
Exposure Estimation and Risk
Calculation
Preliminary Site Characterization
formulation are
feedback loops, particularly in the development of the conceptual
creening stage of the risk assessment is important for this next
'the screening stage usually cannot be used in making remedial
e used as a starting point that will eventually lead to the compilation of
lulation directs the gathering of data connected with the following: contaminants
tential receptors, exposure pathways, assessment and measurement endpoints,
s, and the formulation of a testable hypothesis. The overall objectives of the risk
assessment will be determined at this step of the study. In order to best accomplish this, a
conceptual model for the site should be developed. The development of a conceptual model should
be interactive with all of the other steps in the problem formulation and may not be complete until
49
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all data for the other sections have been gathered.
5.3.1 Site Characterization
The aim of the preliminary site characterization is to compile as much general and specific
':™*£$Sfey «*Sfcj^£^^>:?ffiWK:>.
data !about the site as possible. A physical and ecologlelt descriptiOBJOCJbe site, as wet
-. \ sjS * 5s«viv.XVA vX \ x5Sv
contaminant distribution and related information should'be gathered^THe faptM^hsLinforma^n
should be presented by the conclusion of this step, mucB of it havertb been in
stage interim deliverables:
Contaminants known at the site and the maximum
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EPA Region 10
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which should be assembled to characterize the system(s) present. Additional information should be
provided depending on the needs at the site. Also include a description of all possible transport
routes for all media, including surface water, ground water, air currents and soil. IgfWde diagrams
when additional clarification of a pathway is required.
Table 5-3*: Basic Parameters for Characti
Surface Water Sedi
Field Parameters
Temperature
Dissolved Oxygen
PH
Conductivity
Salinity (marine only)
Flow (width & depth
Layer composition
PH
pnductivity
Laboratory
Parameters
eter
Total suspend
Alkalinity
Hardness
BOD
COD
TD
•_.%. TCaX.
lleable
Moisture
TOC
CEC/AEC
5.3.2
lvalue
Ttaminant Release, Migration and Fate
Informatic
of the ecos
associaiea'with these!
estabj|lfiing the conce
linated media, coi
tsider the follow!
stlands, s
jlati
evaluation will address two questions: What aspects
are artrsk? What are the potential adverse ecological responses
^A 1994a) This information may also serve as the basis for
rmodel. This evaluation should identify all available data on the
: movement and the potential receptors. It might also be necessary
^pathways: potential groundwater contamination, groundwater to surface
'ent-related transport, runoff and erosion from contaminated soils,
bioconcentration (EPA 1989b).
imeters of Concern
Information provided under the "Surface Water and "Sediment" columns was taken from Region 3
interim ecological risk assessment guidance (EPA III, 1994).
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In any ecological risk assessment there are three basic parameters of concern that should
be considered. These parameters are contaminants, receptors and exposure pathways which link
contaminants to receptors. The cohesive identification of anticipated ecolog||al effects of
contaminants on receptors through a particular exposure pathway is esj^tia^prdetermining the
potential for adverse effects.
5.3.3.1 Identification of Contaminants of Concern
At this stage the list of contaminants which wa
assessment, must be finalized utilizing all available
establishing this list include: environmental concentrati
background levels, bioavailability, physical/chemical piopertie
bioconcentration, potency and organism-experienceg||effects (
information has been gathered, the type of analysHHliliiirformed s
chart to help discern contaminants of cone
detailed discussion of soil background oirj&ntratioflir;)
the screening stage-of the nsk
^sssS^"
e factors to consider when
i a, frequency of occurrence,
for bioaccumulation or
Once the above
be determined. A flow
(Appendix C includes a
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SUSPECTED CONTAMINANTS
Data Usability Review
- Analytical Methods
- Detection Limits
- Detection Frequency
• Quality Control
QA REVIEW OF SITE CONCENTRATIONS
Address
Impfica
Rl
Characterization
Comparison to Background}.
- Inorganics
- Radionuclides
- Organic
SITE CONCENTRATIONS^
VS.
BACKGROUND
oncentrat*>t< Back
S»e Concentration > |
Background Concentratjwi f . IAEA
W
imparisogpFReference Values
EPA ABpjnt Water qujlty Criteria
itty GutcWines
Address
Implications in
Risk
Characterization
-BASED:CONCENTRATIONS
incentration < Risk -Based Concentration
'S OF POTENTIAL CONCERN
Address
Implications in
Risk
Characterization
ROBLEM FORMULATION
Adapted from INEL (1994)
Figure 5-3 Selection of Contaminants of Concern
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5.3.3.2 Identification of Ecological Receptors
<
The identification of potentially exposed receptors and habitats on- or near the site is an
extensive task. This activity can be accomplished by utilizing daj| from a vaiileiy.of sources including
field reconnaissance, aerial photography and satellite imagery as;well as inrositat|C«. assembled fro|&
other relevant investigations at the site. Once habitats havj^been dete
associated
with those habitats can be identified. All potential receptors should Jbeldentified;ihclldlrig Species
essential to or indicative of the area's ecological healtf^ sjteCM|S which are rare;^|ijrjid/surface wafer, soil, sediment, and biota) on the site can be
evaluated;* ™
5.3.3.4
ice the previou»;tnre0'Characteristics (contaminants of concern, potential receptors and
pathways) havfrbeefPftJentified, a linkage between stressors and effects on receptors must
lablished. Which jfbfttaminants of concern produces adverse effects on which receptors via
exposure pathw^(s)? Furthermore, what are the adverse effects of the exposures? This
jtion shouldsie both qualitative and quantitative and may even be gathered from the peer
publications. The documentation of all known or suspected effects of the
Jill assist in the selection of assessment and measurement endpoints.
5.3.4 Definition of Objectives and Scope
The scope and objective(s) of the risk assessment should be established early in the process
54
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EPA Region 10
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to insure that a consistent and relevant assessment is performed. They cannot be establishedbefore
the screening stage because they are based on some knowledge of the general state of the site.
Once those data become available, the objective(s) of the risk assessment must tuAt. This step
is an iterative part of the problem formulation process. Defining the Sc9^[^^k assessment
may reveal some data gaps in the current data set; collection d&pre influence the
objective(s) of the risk assessment. The objective(s) gfl^studylHIkLof the probU
formulation step should be included in the deliverable for tr
also be used to determine appropriate assessment end|
5.3.5 Selection of Endpoints
The selection of appropriate endpoints is critical
fecision pj
its for tttfsite.
/e(s) sf;
assessment process.
Assessment endpoints will be used to determine tr
by the scientists involved in the risk assessmj
federal and local trustees and the general llic.
decision point and will be addressed in
problem formulation.
js of the
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EPA Region 10
DRAFT Supplemental RAGS
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Table 5-4 Sample Summary of Endpoints
Assessment
Endpoints
Measurement Endpoints
;. Ssfl'
Alternate Measurement Endpoints
Population of raptors
in Kitsap County, WA
(biological relevance:
control of rodent
populations)
Peregrine falcon egg-shell
thickness.
Number of peregrine falcon
eggs
~t
>~evel
of field mice
"•% /•
Niwriber of peregriWMeoinwits
•
•&.
Coho salmon
populations in the
Duwamish River
basin (societal
relevance and food
source)
Reproduction rates in coho salmon ,^; *'%Sedinent available for spawning
en levels in stream
Visible lesions on the coM
The examples in table 5-4 re^^Sent clealfelationsrsjjps and straightforward measurements.
For example, to assess for the>5tability of the raptok population at a site in Kitsap County
«$? '"s^O. SSS?
Washington, measurement endpoints must afcf ^assessing both current and potential future effects.
.-$>. . *.«. .? \^^s^$^v^
red via number of the peregnne falcon eggs,
eing experienced by the raptor population, while
peregrine fa|con"egg-shell thk^ing w8l serve as an indicator of potential future raptor population
decline. Alternate measurement endpoints should be provided to help assess the same impacts
% % v.^ «,»\« %
should the other measurements notjbe possible. For example, a decrease in the number of
, "KSS""-"' ' V. -
peregrine ialcon nests
conta
futui
"•s
of concern for tttesile) in the food source for the falcons will indicate the potential for
$'
example is presented for coho salmon populations. (See table 5-4.)
~S4te will indicate current impairments, while the levels of DDT (a
Selection of Ajjjessrnent Endpoints
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Text Box 5-3 Suggested Assessment Endpoints
Population
Extinction
Abundance
Yield/Production
Age/size class
structure
SOURCE: EPA 1989e
Community
Market/sport value
Recreational Quality
Change to less
useful/desired ty
Ecosystem
Productive
Selection of assessment endpoints can be a very^mplex'tasfc^&ssessment endpoints are
used by various organizations/agencies and trustees to determine the fcrftportaftce of site remediation
in a broad range of contexts (scientific, politics^ eoonomto and socted)^ Therefore, assessment
•, 5jw-^ S \£ s^ ** **•
endpoints must be easily understood and musl possess^cfear social and biological relevance (EPA
1989e). A more in depth discussion of thf characteifst&^qipd^ssessrnent endpoints may be
found in Chapter 2 of Ecological Assessi -
presents a list of potential assessr
ht of Hazardous
5.4 Step 4: Development
Sites (EPA 1 989e). Text Box 5-3
Model «
the central component on which most of the risk assessment
is based. Hs^velippment assbts V«tH and parallels the entire problem formulation; and it is the
- '•%£?, - ^V, •• •iS'|p^., .•S'iO .
basis for evafMafing^th^ inform^pft ,v>|«ch will be uncovered dunng the course of the risk
assessment. JJjfe PMrPp$M tne coStual site model is to identify:
p^™1 ^iililliilbv
s of contaminants;
known or po
individual co
ants known from preliminary sampling to be present at the site, or
based on known types of current and historical site activities;
environnjjirvtel media that may potentially be affected by the contaminants, including
id groundwater, soil, sediment, air, and biota;
fential contaminant exposure pathways for ecological receptors living on or near the
site, based on collected data or expected pathways;
• potential terrestrial and aquatic receptors at or in the vicinity of the site (EPA 1989b).
57
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.conceptual site model
" inated media and
While the conceptual site model for the overall RI/FS process is included in Phase I along
with the scoping reports (section 1,1 of this document), a more detailed model is necessary for a
thorough risk assessment. The conceptual site model developed in Phase I of trjejpl/FS process
will provide a general model to initiate the investigation. The risk assessm
must now identify true and complete exposure routes, actual receptors
transport mechanisms. It should be a separate model and bjflptcific to^llc£ibi&jical concerns
the site. It should also take into account the selected indpoints f^^he
example of a schematic conceptual model is presented H figure 5^1. It inclu(
OSSWft xy^
secondary release mechanisms potentially associated with ..eich affected matrix. A
5-5, a graphic can also be used to convey this informational
potential pathways by which contaminants of concern
receptors associated with each form of exposure.
and
!ri figure
jmportant to clearly identify all
orted as well as ecological
Figure 5-4 Schematic Conceptual Site Model
58
-------
Ol
VO
Primary Affected Transport Exposure Exposure Receptors
Source Medta Mechanism Media Route _
, t Omlta J Ingesllon I * -
r Subsurf
Subsurface 8o« Uptake
4 1 Ind
Mammal Surfac
Translocatian
Erosion Surlai
l--fja>, a aim. O* A*m» »M
H1MIIHMJII OiWUii
Plant Uptake and
f^fi^M r\ pfrectcontect I + -
.... k| Inaeslton 1 * -
t . pfrsdcontacl 1 + .
a Sol +-mn-.i.--i
.1 Ingeslton I *•
cji ' Dlf Ml Contact 1 *
n kJ Ingaallon 1 * - 1
S"*CJ1 H WrectConlact 1 * . 1
Figure 5-5 Graphical Conceptual Site Model ^^,
(0
c
•o
3 ID rn
o> a TJ
rjff »
•^ — (O
'
«o CJ -i
o> (/) o
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EPA Region 10
DRAFT Supplemental RAGS
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Definition of the conceptual site model will help to identify additional data requirements which
may influence the model. The conceptual model should provide a functional framework for
evaluating potential exposures of ecological receptors using or inhabiting the site,. „"*
,
Ecological receptors are those organisms that may be ojffently e^o$eCto contaminants at
the site or may be exposed in the future. Those spseieVthat oc^i^f^hiche considered
fundamental to the function of the larger ecosystem shoafcf'be docum^^eof^eatfl^^s such
3 ' - * ™-!>«4M - •*
"••$?
the risk assessment report. Site-specific ecological receptors of coRcem can be'selected fp^a site
according to the following hierarchy of considerations. First, Ihfe receptor should be exposed," 'directly
or indirectly to the contaminants, as the assumption is usually, made that an organism not exposed
v.%%W: v.s WA-.
to a given contaminant is not at risk from that contaminant Seoan<£ changes in the community, as
„<• ys,v> „.,,,$;&>,
marked by standard indices, when due to exposure, may indicates fj&fcntial receptor. Third, if a
prey organism serves as a source of exposure to predators (baseef&htlX&y burden and sample
*• iBt?^ "^ sS% >^».»:M.»».SM''
model), it may also be a potential receptor on the\f$0d; eliairi.
%
Although individual changes may sometimes be coft$lde?i$4Hgnificant when threatened or
«• » •, , --«£*s w£~ *
endangered species are among the receptors, ecological ns& assessments focus on effects to the
overall ecosystem at the site (e.g., stfcfc-as population changes). Impact on critical species on the
food chain structure can affect the efttfre ecosystem. While, organisms higher in trophic levels often
attract the most attention, effects" of cont3ffiiBantS™Q|j,Tower trophic levels (e.g., decomposers,
i *V* *• --J T $&
detritus feeders) must atsct be considerad, fc«r,; example, a contaminant may be toxic to
^^^ss•.^•C^ \ •.-.-.v.v -. 1 • sss-. v, \ i,\-
•.^•C^
microorganism?* :$t very low concentratiorrsr, vahd if microbial or invertebrate populations are
"-s """ " s - " ~
disrupted, decoirj|)QsWon of dead plan! and animal matter may not occur. This in turn, may reduce
S V».^S> ^HS^SSS ^ "*J^ •. S •,-.•,•, •. •- V.
the mineralizatfort jiFQcess needed Id susiain the plant community. Eutrophication may also result
from similar mecnasltSftts in the aquatic" system, causing the depletion of oxygen that is vital for
KHgwa • •• •
aquatic life-fofms.
FA complete expo^Ufe\;;pathway includes a source, a mechanism of contaminant release,
re||pion and/or transpjp influences, a biotic exposure point, and an exposure pathway at the
pica! exposure poilr Only complete pathways are expected to produce a significant exposure
jceptors. Ay|*!posure pathways documented in the risk assessment should be accompanied
tipn of the aforementioned properties. These pathways will help to determine
isurements for evaluation of chosen assessment endpoints.
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Text Box 5-4 Suggested Measurement Endpoints
Individual
Death
Growth
Fecundity
Overt symptomology
Biomarkers
Tissue Concentrations
Behaviors
Population
Occurrence
Abundance
Age/size class structure*^
Yield/Production \ • ";''v^
Frequency of gross mortfidity ^
Frequency
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EPA Region 10
DRAFT Supplemental RAGS
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able to be evaluated).
An assessment endpoint, as defined by G. Suter III in Chapter 2 of Ecologuj^f Assessment
of Hazardous Waste Sites (EPA 1989e), is "a formal expression of an adibal etjyifonmental value
to be protected. It is an environmental characteristic, whichj|tf foundJ^b^lgnificantly affected,
would indicate a need for remediation." While the highe
ecological aspects of the RI/FS process is an evaluation;
assessment endpoints are usually the highest level vai
objectively.
essmen
the ecoli
s at thfc?iite whicl
in the overa|
Measurement endpoints are "quantitative. expressiorVS^^b^jaryed or measured effects of
a hazard; and, these measurable environmental chiracteiisWcSo-afe.vrelated to the valued
"58SS&" s^?«^
characteristics chosen as assessment endpoints (EPA,1989e)." Measurement endpoints are those
V ^^S^S5S!^5, *W&Oi8^
criteria which have been selected to serve as indfcalQfS
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EPA Region 10
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5.4.3 Selection of Study Design
/&
At this juncture of the risk assessment, the conclusion of the problem fomriulfEron, including
the conceptual assessment site model, the two associated sets of deliverables should be submitted
to the project manager and the corresponding decisions made:\The fdfowiflg'fluestions should be
addressed: Are the stated objective(s) appropriate? Do the4r$:fbints sufiport'Vl&cussed, efficiejl
and effective ecological risk assessment? Have the exposum^pathways pert aieqti^eJy identipff?
Is the workplan clear and thorough? Any additions offbhanges- plcessary ^rjC«mS^g|iythe
specialized tasks indicated in the workplan should be deteiypned^ Once these quesij^iiijf^e been
addressed, the risk assessment should continue in accor^anca!wit(i the workplan.
5.4.4 Literature Search
V •. ON:
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EPA Region 10
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The site assessment is the confirmatory step on the magnitude of exposures of receptors
to contaminants at the site. The site-sampling and measurements required for this step are both
diverse and specific; a number of different skills will be needed. These skills and theporresponding
measurements should have been determinedat the decision point following the problem formulation.
5.5.1 Sampling and Analysis Plan: Quantification
Contaminants
Sampling design should be clearly laid out in th&
fri as influenced t&lhe decisions
« js*>*
ion step. Sampling should be
made and the associated deliverables at the problem
thorough and based on sound judgement taking into cons&irMon&ilavailable and relevant data
about the site. Direct sampling of media is obviously not the only flfwthB&available, but it is useful
ws ""j&vi \ \ •••JSP&b.
and will help to identify the current migration of contaminants as wettlsJHeJNinsport mechanisms.
These data will also help to predict future migration paltems- ^the contatx^nts from the site. Any
s\s^s^w»*s\ \,A •• """"••Sis?*), $&
sampling of background areas should be included in thf SSSrppUng and Analysis Plan.
5.5.2 Verification of Exposure Path\
Characterizat
'Receptors
Characterization of receptOfsTshould
™W
at the site), and may further be, limited to those
and asse
habits, li
at the site
observations
assessment
imited to/ffte receptors (not all organisms present
^ v si ^ --f directly associated with the measurement
it endpoin&I Information tolle'^ioiected in this step includes: species' feeding
^s^X-*,-^ VJP&Ci^ '
habitat preference, and othefattributes related to sensitivity to the contaminants
% %v£y w 5 ^ >.yQ v^
This tafarmaJion should be available in published literature, but some field
"*<&•»& WS^ C^
essenttaL^ll.pertinent data should be assembled here to insure proper
Contaminants on given receptors to minimize uncertainty.
5.5.3 Estimation of ExpQ&wetgbint Concentrations
*jp ^Q&iijjiljr
?si& ~*%Sjr
jjj ™
This step will djpend on which receptors are associated with the measurement (and
ssment) endpoirjif Media which are the potential sources of exposure of receptors to site
linants sho.ulinbe sampled and analyzed to determine the levels of contamination. To
1 point concentrations, more data will be needed to facilitate the estimation of
'the exposed group of receptors. This information may include: properties of the
contaminant, ecological effects, the nature of the receptors and the physical and chemical properties
of the media (EPA 1989b). Table 5-5 shows sample intake calculations. In the case of
bioaccumulation of contaminants, biota samples from at least two trophic levels should be collected
from the site and evaluated to determine the site-specific bioconcentration and bioaccumulation
64
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EPA Region 10
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Table 5-5 Sample Intake Calculation for the Deer Mouse
Chemical of
Concern
Lead
Concentration
(soil; mg/kg)
150
Daily Intake
Soil
(mg/kg-day)
6.4
Where:
Daily Intake Soil
(Concentration,,,, x soil ing$stion
(150 mg/kg x 0.0006 kg/4ay)/0.02 kg
4.5 mg/kg-day
Daily Intake Invertebrates
Dai!
factor,,
Invtrtctanu '
invertebrates in dtetx faod7day)body weight
(150 mjlg x 0.65 jtjf^fx 0.007 kg/day)/0.02
facforiMinvertebfjijis estimated from literature.
w
seed in diet) + (concentration,^, x %-leaf in
x food/dSpSody weight
x 0.40) + (16.3 x 0.14)) x 0.007)/0.02
lay
''ed and leaf tissue measured at site (hypothetical).
|rily intake,,,, + daily intakelnvwMbnll + daily intakeptant
f4.5 + 12.97 + 2.0) mg/kg-day
19.47 mg/kg-day
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Table 5-5 Sample Intake Calculation for the Deer Mouse
s
DEER MOUSE PARAMETERS
Soil Concentration Lead
Body Weight
Bioconcentration Facto^t^^^n^^
Percent Invertebrate in Diet
Food Intake/Day
Concentration of Pb in Seed
Percent Seed in Diet
Daily lntakepllnt
Concentration of Pb in Leaf
Percent of leaf in Diet
5.5.4 Toxicity Tests
Toxicity tests should only be coriBucted j^if measurepents which are directly pertinent to the
objective(s) of the study from tfctf perspec^e$\pi;oyt|ed by the assessment and measurement
endpomts^T^pxicity testing CUfV prolong (iffi^ Jrpsrease the cost of) the risk assessment, while
clouding j|Wj^J|inis of tl^elsk assessment lhls>providing virtually no helpful information. Text Box
5-7 lists re6oiit»ni«d toxicit¥:Ve«O^different media.
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Text Box 5-7 Possible Toxicity Tests
Aquatic — Microtox*
Fathead minnow
Rainbow trout
Sheephead minnow
Dapnnia magna
Fetal Embryo Assay (FETAX)
Root Elongation/Seed Germination
Terrestrial (Soil Contact Tests)—
Earthworm Bioassay
Seed Germination
Plant Uptake (For Food Chain Transfer
Potential)
Microtox* (solid phase)
Soil Elutriate Te
otox*
bn/a rrii
: Elongc
rSediment:@Striaf
fa dub/a5*
i magna
., #&?*>
BOfft Shipment Tests
Biva
Rhepo
Sea cucu
urchi
5.5.5 Toxicity Bioassays
'7V?*. v ' i+*
level bioassay$&l
(the organism
effects)
assessmentand more
v iJF'
within tl»>natrix. If the
ipiiinjed for elWmatrix (water, sediment, and soil). The screening
ation, essentially identifying whether the matrix "passes"
adverse effects) or "fails" (the organism exhibits adverse
*fails" the bioassay, it must be carried through the risk
le conducted to evaluate which contaminants are contained
the bioassay, it may not require further analysis, but should
ation and uncertainty analysis. However, before making such a
the potential contaminant(s) must be evaluated using information from
Moratory methods such as chemical tests. For example, a particular
inant may bjfPSuspected to exist at levels of concern in a given medium. A screening
Administered on that medium using an organism likely to be effected by the
the medium may "pass" this bioassay test. A chemical analysis revealing the
presenSTof no significant amount of the contaminants in that medium could then be used in
conjunction with the bioassay toconclude that the medium in question does not pose significant
threat to the ecosystem. Hence, the bioassay for each medium of concern can serve 1) to indicate
a potential stressor in the media and 2) to validate chemical analyses corresponding to each
be
dc
tt
lined for risk cha
nination, the natu
terature or othec
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medium.
5.6 Step 6: Field Investigation
5.6.1 Site Investigation and Ecological Effects Assessment
This step provides a link between exposure to contaminants and
at the site. It focusses on dose response relationships. < Sbme of
v%vt
the literature, some can be determined from laboratory,
measured in the field. Regardless of the source of the data,
associated with it; it is important that as data are code
dearly understood and documented. This will be extremely useful
5.6.2 Field Studies
A well-conducted field study can provide a va
potential ecological effects. The field study will help to det
within the site. Several "endpoints>jire considered evid
evidence includes:
qn recepprs
in
ests
and some w$,rieed to be
^&»s>»
e some degree of uncertainty
ainty associated with it be
characterization phase.
site contaminants and the
conditions of the organisms
of an adverse toxic effects. Such
the
reduction in specie
£•_
spikes icflawn to inhabit the area,
wsswr*^ '" s^'si ^
presence ttfp&mt or anfmal.Sfieoes associated with "stressed habitats,"
ch
balance or trophic structure, and
rs or other pathological conditions.
lerature can also fjpvide an expedient and available means of referencing pertinent toxicity
lation. Howevejpoften the literature does not contain the species-specific or surrogate
required JiiPlhe assessment. Although field studies involve additional time and cost, they
Jecific and species-specific exposure and toxicity data which can reduce the
Trisk assessment and contribute to a stronger ecological risk characterization of the
site.
5.7 Step 7: Risk Estimation and Characterization
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Risk characterization is the final step in the risk assessment process. All calculations and data
from exposure and ecological effects assessments can be related to the objective^) of the risk
assessment through the conceptual model and the assessment and measuremenylllpoints. The
ecological effects and exposure assessments should have been gui|pKb^Jp measurement
endpoints, thereby providing a link to the assessment endpoirm. All releilllilpnmation should be
presented in this section of the risk assessment. Both cur
must be addressed. The predicted adverse effects shoi
conceptual site model, the uncertainty encountered ancft
A recent memorandum (EPA 1995a) issued by the EPA%3mmtsirator articulates the importance
0**$S. %v. V *3s N
of good risk characterization, emphasizing "transparency, clanCy7consistency and reasonableness."
All analyses, conclusions, resulting decisions and critena employed to amve at such decisions must
be made obvious and be clearly presented. Basic assumptions and.sdeftttfic policies should be
consistent and grounded in science, with carej^elit'tO>cdvoid overfy^nservative approaches.
Sources of uncertainty must be clearly presenili and^kjSlaHiict,, The .memorandum outlines three
guiding principles to direct risk characterizlfon:
1 The risk characterization h
response, and exposure
quantitative information,
character
makers®
Risk chajaiferizatioi
specifupmy directed to\/
upcoming Guidelines fo,
the hazard identification, dose-
\bination of qualitative information,
uncertainties.
of uncertainty and variability.
tions present risk conclusions and information regarding
Assessment for other risk assessors, EPA decision-
expanding on the aforementioned memorandum, and more
ilogical risk assessments, is currently being developed within
Wgical Risk Assessment, by EPA's Risk Assessment Forum.
Hsk characterizatioWshould answer the following basic question: Are ecological receptors at the
jected to bj^pfposed to site contaminants at levels capable of causing harm to the overall
ticular valued species within that ecosystem, now or in the future? An analysis
Tduring the risk assessment process will enable the risk assessor to determine risk
estimate(s) related to the conceptual site model and the chosen assessment endpoints. Subsequent
discussion regarding uncertainty and ecological significance will help to put risk estimates into a
perspective allowing for sound remedial decisions. Discussion of risk estimates should identify the
strengths and limitations of the risk conclusions in such a way as to provide a "complete, informative
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and useful" set of information for decision makers (EPA 1995a).
5.7.1 Risk Estimation and Uncertainty Analysis ^ ^
Data analysis focuses on the first phase of risk characterization, risk«siiftiation. The ground
work for data analysis is laid long before the risk charactenzartlofi stage dt^l^l development of
the conceptual site model and in the choice of assessment and measurement sndpornts. Trgfcse
steps guide the data analysis by focussing efforts on preselected representatr^e;^ifnponertt(s) of
the ecosystem. Such components should account for jsensjgve subpopulations and specific
individuals, as appropriate, as well as the overall health of the site's ecosystem. In what ways these
components are indicative of the overall health of the site^hoold^be summarized in the ecological
significance portion of the risk description.
Risk estimates should integrate exposureyand toxtc^;,:informatfofi:4n a way that supplies a
measurement of adverse risks. Such a mealureme«tifnay Ba.a qualitative description, such as
.•iSS^' '•y^y*' % wv» !™sv. fyp
"high," "medium," or low" or it may be a:|iantitatiye value/ojIl^-W'values such as a quotient or
range. The type of data evaluation emgfpyed in the screemRguSiages of the risk assessment may
or may not be appropriate for the finable estimation. For celtaminants which were "screened out"
of the more in-depth data gathering'event ofithe risk assessment, the conservative screening
estimate may be discussed in th&Yisk chara^e'HzatJon pfiase. For those contaminants "screened
in" to subsequent stages.of the risk assessment additional data to supplement screening level
- si-^^sj... v.-mj-"^,---- s1 «--5--sssyi "NJ*'
information fSlwald^ be usedtO;hef|5 characterifzelhe risk.
- s«-, ^; ;4,
-^
If a hazard <^otlefiite to be usect lo «$ttmate risks at the site, refined data from the site-specific
exposure and toxicity inv$s8gations associated with steps 4-6 should be used to calculate the hazard
- •
s«...s « . v «™ •. ^
quotient. Ihrdose in ecttialJcaf 5-1 may be modified from a simple exposure point concentration to
w- s y&t +*\^
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angles considered, the more data presented and the greater the potential confusion.
To avoid clouding the risk characterization with unclear or inapplicable data, alfefta should be
presented clearly, and in the context of the associated endpoints wU&b^theliflustration of the,
conceptual site model. For example, whether a point estimate of inta|| represents a maximally
exposed receptor or an average-exposed receptor must fce\cfearly stafedreri^a change to tr»
conceptual site model was discovered, it should be clearly slated beforf fe?at«cf5ci|s discus
if an extrapolation from toxicity data based on a related;^t differept<'spec
Essentially, the "line of evidence" leading to the risk esti|jatea^hould be presteich an
analysis is necessary in both quantitative and qualitativeBsk'isfimation. Describe the source of
toxicity and exposure parameters, the reasoning behind professional; jti&gements and any inferences
applied to the data.
^^ W " •; ? ^s' f "^ £•
The time scale for effects predicted by risk esjiiiinatloTi io>occur shouldJaiso be noted. It may be
presented as an absolute value (e.g. number of^ays'or.y^aiPs)* and it it*ay also be presented in the
context of the life cycle of receptor(s) effected. Deforestaitoo::may take decades, while depletion of
microbial fauna! communities may take days. Similarly, the tlft)&&r a system to potentially recover
from the projected/observed effects
5.7.1.1 Current Adverse Effects.
cies withiirthat ecosystem? As discussed above, a qualitative or
<- tf? '
d on evaluation of assessment endpoints in the context of the
Infouttatlon ptesentel^rnUSt 8&clear. Although data associated with the risk estimate(s) may
be complicated^^i ^informa^&rt^sought is straightforward: are ecological receptors currently
exposed to site contaminants at levels capable of causing harm to the overall ecosystem or to the
*> ^ *4» t~«»3&i. % >5S v * **'
or to particul
quantitativ^rfsT esfii
concepjlal site model1! presented. Any assumptions, equations and/or professional
judge^nts utilized shoull ^plarly presented as such. Any adverse effects predicted by the risk
ailed with the types, extent and severity of the effects (EPA 1989b).The
r, as well as the time for such effects to be eradicated/mitigated, should
dverse Effects
As with the Current Adverse Effects section, this information too should be presented in a
straightforward fashion. The question is essentially the same: are ecological receptors at the site
expected to be exposed to site contaminants at levels capable of causing harm to the overall
te(s) should be d
r such effects t
ssed.
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ecosystem or to particular valued species within that ecosystem in the future? Again, a risk estimate
should be presented along with any relevant qualifications/clarification of the data. Anticipated
adverse effects should be described regarding types, extent and severity (EPA 19||i!. A time line
for effects and recovery should also be included.
5.7.1.3 Risk Calculation
Risk calculations may be used during screening as Will as la
process. When used in the screening process such
estimates (worst-case-scenario). These results will not
rather they will assist the project manager in deciding which
risk assessment.
Ecological risk calculations primarily invol;
referred to as the toxicity quotient (TQ).
ent
!S* ! * \~~rof
must be based Viiih conservative
«58$8>~
set remedial or cleanup goals,
hahts will be carried through the
quotientSQpQ), which is sometimes
iw to calculate the HQ.
sv
HQ =
hazard quotient ,
level of cotrtarrtnation to
in
toxicity ri&«$yalue (an a'
ism is exposed expressed
Risk-Based Concentrations or
Equatfdirt 5-1 The Hazard Quotient
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(a) NOAEL = Acute or Subchronic LOAEL/10
(b) NOAEL = Chronic LOAEL/5
(c) NOAEL = (LDso/5)/10
(d) NOAEL =
(e) NOAEL = NOAELdw^d.,Mm.elass/2
(f) NOAEL =
SOURCE: Sigil & Sut»f. 1989.
non-protected.
protectedspecies)
Equation 5.2 Extrapolating to NOAEL from
LDM; NOAEL of related (d) family, (e) order,
i) chronic LOAEL; (c)
During the risk calculations, if no:|iii&ased cjncentratio|palues are available, the no-observed-
adverse-effect-level (NOAEL) shoujlpfused aiilhe toxictwreference value (TRV). To extrapolate
to the NOAEL from a related value|pquation|::|ii|^-p:::p|y' be applied. When no related values are
available, screwing level may be lack of data cannot be used to justify the
Int; a screening level qualification of "insufficient
contaminant should be further examined during the risk
assessment pi
Utamiriants are found at the same site, and a cumulative effect is
aid be calculated. The HI is simply the summation of all HQ's
Sntaminants for all pathways for each media as shown in equation
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HI = EHQ
T^ HI
EHQ
Hazard index
The summation of all hazard quotients of related
contaminants of concern
Equation 5-3: The Hazard Inde
Hazard Quotient (HQ) values greater than or equal to one^ndicate a likelihood of risk.
Contaminants with an HQ 2 1 should continue to be evaluated WoioeSinXJut the following stages of
the ecological risk assessment. Contaminants with an HQ < 1"\s&butd be retained only for
consideration in the uncertainty analysis and risk characieriza.tjon of the^ecotogical nsk assessment.
.. nS-^ •• ,' « \ "^
Exceptions to the latter include (1) single contaminants WdttjHCt^1 whi^f contnbute to one or more
HI z 1; and (2) contaminants with the .potential \fr 'bfoaooi^^! Contaminants which may
bioaccumulate include, but are not limited to, PCBs, PAHJ^tstdmium and mercury. Enough
information about the nature and extent of contamination roust be provided to enable the project
manager (with guidance from Refipfial BTAGjf to decicfepwhich contaminants should be carried
through the ecological risk assessment. Th&foazard indCx (HI) is evaluated on the same principle
as the HQ.. AnHI of greater than or equal ferine jscRcates a need for concern. An HI of less than
one indicates that contrtbulno;, contaminants-may be set aside for risk characterization and
••- •••• %\ '•SS'-V •. , 55,
uncertainty af»g!ysis&,Best prqfsssioflajjudgement must be employed in a hazard-quotient-based
screening proc6ss.h;;.
5.7.1.4 UncertaintyAnatysfa?*'
•,*>" .*.?>.'$&*.*<(!.>
riably, uncertaintV;v^|;be associated with a quantitative risk assessment. Uncertainty is
w ^
jced at many pointsalong the progression of the risk assessment and its extent varies greatly.
preserjlfn the values obtained, the model chosen and the scenarios chosen.
""ff
Extent, uncertainty must be documented. One of the most common criticisms
fsessments is inadequate discussion of associated uncertainties (EPA 1992b).
Ssion of uncertainty does not lend a higher credibility to the data presented, it simply
hampers'the subsequent decisions by preventing an informed evaluation of the data. Sources of
uncertainty include natural variability, measurement error, sampling error, human error, extrapolation
mandated by an incomplete knowledge base and incorrect assumptions and oversimplification.
Each contributor to the uncertainty of a value or decision must be documented in the risk
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EPA Region 10
DRAFT Supplemental RAGS
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assessment at the point where the data are introduced; and all uncertainty associated with data
presented in the risk characterization should be summarized here. When possible, uncertainty
documentation should include a quantitative component.
A sensitivity analysis of parameters may help to identify yftjich
impact upon the risk estimate. Further, those uncertaintyJacWs with
reduction may be discerned. If data uncertainty, including that attnbutabj^o
professional judgement, and possible error are tracked during thdkpreceding
assessment, the risk characterization will be simpler to
most significant
potential for
^assumptions,
' •
Uncertainty analysis is used to quantify some of the uncertainty associated with the prediction
of a risk assessment by describing the uncertainty of the inputs t
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EPA Reg ion 10
DRAFT Supplemental RAGS
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Hazard Quotient Belted Kingfisher
Freque ncy Ch art 5,0 1 2 Tria
0
I llllilri.k. _ .
^25 5 7.5 10
1
Is Shown
650
- 487
-n
3
- 325 -g
n
- 162 5
0
Figure 5-|f Frequ|$£y Clis
Hazard 9$pent for^fe BeltedORirTgfisher.
Figure 5-6 shows an examplej^results J|||n a MonjJEario uncertainty analysis. It examines
the uncertainty in the exposure, mtlel predic^^^u^^^ncertainty in the model inputs. The chart
shows the ra|tge of possible yalues; a cun|i^P|||jfIrt derived from this output would show that
^ &****• •. &m •" «* *t>$i%$$&i8tfjS'f
about 8Q%.«5f..tte,values predict a hazard quofeM below one.
The Montft,'Ca>l ifoethod hals'lhe benefits of better describing some of the risk assessment
";»s&»s» ^t.......^ *• ^stit •••• "-ys
uncertainties ye
parameter^
effort hpts application afi^|p^j|>ssibility of being misapplied or possibly misrepresenting the risk
asseJifnent uncertainties
; qualitative description. It also forces a closer look at all of the model input
^^ ^yf^w.y, y+Jt^ t<&
ier to assigri iistnbutidns. However, this technique has the disadvantages of added
use of Monteirio uncertainty analysis is encouraged in appropriate cases. Because of
tential to cojppicate the risk assessment, before a Monte Carlo uncertainty analysis is
tractor must present, through the RPM, its proposed use of Monte Carlo to the
•approval. Documentation of the proposed use and its projected advantages should
be provided. Some of the requirements for its usage include:
A description of all assumptions to be used in the application of the method;
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• A full description of distributions used in the analysis and the basis for each, including
possible alternatives;
• A sensitivity analysis describing important model parameters; ., ,J^
s '4'\ ff
• A description of the uncertainties that are not described by the MoRtft Carlo analysis; Is it
variability and/or uncertainty that is being describedKfr* --
">
i
A computer disk of the risk model and assumptions made in
*
The Monte Carto analysis is not necessarily appropnafe'&r,aJi Situations; howevvippears
to offer a better analysis of data for a given site, the above Information should be provided to the
RPM and a discussion initiated to facilitate a timely and informed decision.
,5.V %%s •" s*
5.7.2 Risk Description and Interpretation of Uncertainty
Once calculations are made, and accompanying Uncertainty presented and analyzed,
»»• ,_*£. \ w-- *--*-*•"• V-WA" _t
conclusions must summarized. What define numencarr
present at the site. Utilizing the conceptual site flfiodel
and
? What ecological risks are
endpoint analysis strategy, can a
dear relationship of cause and eff
on the ecosystem. What are the
focusing questions which shou
risks are to. |fe. compared 1a
qualitative or ^ul^titative.l
. 'vSfc-^ •• .. 'ffi. -
5.7.2.1 Interpt
own for:between dlven contaminants and specific effects
5BS8'5^ ,_ . '•^ *
^ations-ofthe varioqi uncertainties? These are the types of
e answered: in. this final section of the risk assessment. If site
ground ry&/d
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EPA Region 10
DRAFT Supplemental RAGS
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and a discussion of these changes is the concluding portion of the risk description. Risk estimates
should have been determined during data analysis, a discussion of the line of evidence leading to
these estimates should have been initiated during data analysis and continued intQjpl uncertainty
assessment. Remaining is an interpretation of the ecological significanjil|f thjjpstimates. Such
an interpretation should follow naturally from the conceptual site rJltlllild the assessment
endpoints chosen to evaluate the site.
This section should begin with a brief recapitulati
modifications made to it in the course of the subseqi
hypotheses chosen to evaluate this model should be deso
for evaluation. For select key hypotheses and endpoint
in support of this decision should be offered. Any critical :i
be identified, as should any points for which a con.
should be rare, but may, upon occasion,
proceed on the risk assessment, and this nrary^Be
professional judgement will be used to assess ecotogl
noted as such.
The ecological significance of cisto present:
scale, both spatial and temporal, plpffects ai
Measures fqrj^aluating thejgj*pg|cal signii
and co
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EPA Region 10
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assessor. However, the project manager utilizes the risk assessment in conjunction with available
remedial options to select a preferred remedy for a site. It is imperative that the project manager
understand the risk assessment, including uncertainties and other limitations. Thjjpliderstanding
is crucial to the project managers ability to select the best remedial acti|||for jlfK For instance,,
a risk assessment based on field study data which includes sorties of be appropriately
weighted in the risk management decision in comparisoJlPl riskl^MM built around^
literature search and/or toxicfty studies on surrogate specie*
to all risk assessment data be clearly documented.
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6.0 RISK ASSESSMENT TASKS FOR THE FS
6.1 Risk Evaluation of Remedial Alternatives
Depending on the results of the risk assessment, these alteratives
concerns, human health concerns, or a combination o|£lpft;1wo. P:
Assessment Guidance for Superfund, HHEM provide guidance on cal
based remediation goals and risk evaluation of remedial alternate
fee based on ecological
B and C of the RisK
ion of human healtn.,nsK-
- ~s$r- v-™5 '-•"**, v$r
s. However^|>ec&£f£&inese
processes involve the integration of risk assessment with management and feasabl^concems,
specific deliverables and level of effort will be determined according to the needs of each site.
6.2 Scheduling of Risk Assessment Deliverables for the FS
.V.-1",-", ^ "^r5*;
Risk assessment tasks for the FS must be integrated &£fcie FS proeelss'' The risk assessor will
need to provide risk-based concentrations, as develoj^ r evaluations of long-term and short-
term risks. These pieces of informatipn' may be called forJ^ separate deliverables at the discretion
of the RPM. This would probable neces
'-lead sites.
•.\vA8 v- .,- S '••.', " %£• "\ "
At some!»lesx incineration of hazardous materials is considered as a remedial alternative. In
"•*">• ^ o -3*, ••" ,", *"-">,
such cases, iner^ are,risk assessment: related tasks which must be performed. A list of guidance
documents, addfesslngboth screening levef evaluations and baseline risk assessment activities, is
provided in se<^OfiTx«'''.>>'«'«>iy.v.i>'. ;••• v-s, v$fp'%v- \Z
conceptual,
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EPA Region 10
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7.0 RESOURCES
7.1 Human Health Risk Assessment Resources
7.1.1 Agency Guidelines for Risk Assessment
Risk Assessment Guidelines of 1986. Office of Health and EnvironmentafA
87-045. (Also published in the Federal Register, September^, 198&iS5 FR 3:
guidelines include:
ese
• Guidelines for Carcinogen Risk Assessment
• Guidelines for Mutagenicity Risk Assessment
• Guidelines for Health Risk Assessment of Cheijcpcal
• Guidelines for the Health Assessment of Suspect Develdpmenla3 Jpxicants
More recent risk assessment guidelines:
*?y ^ ~\
&&& •Z^jXK •*--.$ ^ v?
• Draft Revisions to the Guidelines for Catfcmogem^f&s#: Assessment, Review Draft
(EPA/600/BP-92/003, August, 1994)
Report on the Workshop.
94/005a, November,
The
ncer f&sk Assessment Guidelines Issues (EPA/630/R-
Risk Assessment (EPA/630/R-94/007,
«. 1992. Federal Register, May 29, 1992. 57 FR 22888 -
EPA Administrator Carol Browner, March 21, 1995.
EPA 1988. Background Document 2 in Integrated Risk
on-line database.
i Methods for Deyjj&pment of Inhalation Reference Concentrations. Office of Research and
jpment. EPA/jpl8-90/066A.
T
Use in Health Risk Assessments. EPA 1988. Background Document 1A in
information System (IRIS), EPA on-line database.
7.1.2 References for Toxicity Assessment
Integrated Risk Information System (IRIS). EPA on-line database. Contact IRIS User Support (513-
569-7254) for information on access to IRIS through vendors.
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Health Effects Assessment Summary Tables (HEAST), EPA 1995. (OSWER Pub. 9200.6-303(95-1),
or EPA/540/R-95-036). HEAST is available to the public through NTIS (PB 95-921199).
Reports on specific chemicals can be found in Toxicity Profiles, from Agency for T^fc Substances
and Disease Registry, and in Health Assessment Documents and otheV^ettifcal-specific EPA
reports.
7.1.3 References for Exposure Assessment
Draft Exposure Factors Handbook. EPA, 1995 (NCEA)^
Exposure Factors Handbook. EPA 1989. Office of Heal
600/8-89/043.
Superfund Exposure Assessment Manual. EPA 1988.
88/001.
-95/002A)
/ironmental Assessment. EPA
Air Pathway Analysis Procedures for SupetftifKf'A,
Planning and Standards. EPA/450/1-89/001002,00
>onse. EPA 540/1-
. Office of Air Quality
Dermal Exposure Assessment: Princjpfes and /^pV/car7on$jfiPA 1992. Office of Research and
Development, Office of Health ancyiif onmenljti Assessment. EPA/600/8-91/011 B.
Exposure Assessment Guidelin&£^992. Federal Regislir, May 29, 1992. 57 FR 22888 - 22938.
,X •*?• W^ftWWl''^e of Solid Waste and Emergency Response. OSWER
Directive No. 92^7^31 A^ EPA 54^1-8^/002.
Risk Assjjjj^ment GuWiiiiiye *?&> Superfund, Volume I, Human Health Evaluation Manual, Part B,
Develojihent of Risk-bWie&ffyflfediation Goals. 1991. Office of Solid Waste and Emergency
Respjpise. OSWER Diresjftillo. 9285.7-01 B. EPA/540/R-92/003.
sssment Guidajjie for Superfund, Volume I, Human Health Evaluation Manual, Part C, Risk
3tion of Remedjj?Alternatives. 1991. Office of Solid Waste and Emergency Response.
Directivej5if9285.7-01 C. EPA/540/R-92/004.
W Guidance for Superfund, Human Health Evaluation Manual, Supplemental
fandard Default Exposure Factors. 1991. Office of Emergency and Remedial
Response, Office of Solid Waste and Emergency Response, Directive No. 9285.6-03.
Supplemental Guidance to RAGS: Calculating the Concentration Term. 1992. Office of Emergency
and Remedial Response, Office of Solid Waste and Emergency Response, Directive No. 9285.7-
82
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
081.
Guidance for Data Useability in Risk Assessment. 1992. Office of Emergency^ Remedial
Response, Office of Solid Waste and Emergency Response, Directive N.^9285JpliA and B.
Risk-Based Concentration Tables. EPA Region 3 continues t|glistribu^^^luable Risk-Based
Concentration Table, however the updates will now be proyj|piemi-af^Si|i^ead of quarterly
The most recent version at time of release of this guidafpB can be yP||ii|^|ndix B of till
document. Updated copies for from Region 10 may obtaijf copy by cirfactifiplifcftci Baajffus
at 206-553-8209. These RBC tables may also be df^loadedlfrom the at
uhttp://www.epa.gov/docs/region3/hwmd/riskmenu.H|^^l^ ''f****mm^
Soil Screening Guidance, Draft (OSWER 9355.4-14FS; EPA$[$RW101; PB95-963529).
Technical Support Document: Parameters and Equations Usei^^^^^ited Exposure Uptake
Biokinetic Model for Lead in Children (v 0.99d), £Q§!|||p 9285.7^||lpl540/R-94/040; PB94-
963505). (The original guidance manual is desi^^^^^^^40/R-93^^^NTIS order number PB
93-963510; OSWER Publication No. 9285.7-|p^*T^||||^^i|:ter nuj^er for the model software
is PB 93-963511; OSWER Publication A/o.^i85.7-7^^||||^|||^f
Superfund Mine Waste Reference Djzjjjrnent. [filon to be^iised] (This document will have a
human health risk assessment chaptjjjjeared towards minirmsites, and will also address the larger
_. __ . 'jWrWtiW* ».<¥# Xfif • "
RI/FS process.)
7.1.5 Risk Assessment fortnctieration
The following,is a list of guJ<$aRce:Svailable for conducting risk assessments for incinerators:
jr-" ••'•. - ^ * ^s»^!^S\'! %<«\ **
Associated with Indirect Exposure to Combustor
final, jrkiary 990 (EPA/600/6-90/003).
Ajjjjjindum fo^^^^^^y for Assessing Health Risks Associated with Indirect Exposure
*""""^'"iExtemal Review Draft. November 1993 (EPA/600/AP-93/003).
Guidance for RCRA Hazardous Waste Combustion Facilities, Draft.
30/R-94/021).
Vfication of Screening Guidance Fate and Transport Equations. November
Issues for Modeling the Indirect Exposure Impacts from Combustor Emissions.
(Memorandum dated January 20, 1995.)
7.2 Ecological Risk Assessment Resources
83
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
7.2.1 General Guidance
Framework for Ecological Risk Assessment. 1992. EPA/630/R-92/001
A Review of Ecological Assessment Case Studies from a Risk Asse
EPA/630/R-92/005.
ss ysSgir'
Risk Assessment Guidance for Superfund, Volume II, Etj$ronmental^
Office of Solid Waste and Emergency Response. EPA S$b/1-89/OJ
Ecological Assessment of Hazardous Waste Sites: A
EPA/600/3-89-013.
Guidance for Data Useability in Risk Assessment. 1992?!
Response, Office of Solid Waste and Emergency Response, Oil
fo
The following recent publications contain info.T,._..-TT
Copies may be obtained from the addresses indicated.
lit perspective. 1992.
Ecological Risk: A Primer for Risk Atenagersr(EP/
Prevention, Pesticides & Toxic^Substances^CiS EPA^j
Jefferson Davis Hwy; ArtinglfcriSv'A 22202.
Summary of Guidelines forpontamini
199% Washington Department of E
Olyilta, WA 98504^7600; (360) 4
1989.
Emergency and Remedial
3285.7-09A and B.
>.
'gical risk assessment.
1). January 1995. Office of
7C) Crystal Mall II (CM-2); 1921
(WDOE, Publication # 95-308). March
ion; Distribution Office; P. O. Box 47600;
Mhe DenvaffQ&Qf Canadian Sediment Quality Guidelines for the Protection of
C^inc¥irfsMinisters of the Environment, Report CCME EPC-98E).
March S>";^idelinei?i5lv;Ts16n; Evaluation and Interpretation Branch; Environment
; CANADA
:S. EnvironmerrtaP.
Superfund: Pro
draft. Edison.
U.S. Enviro
Ecological
ion Agency (EPA). 1994. Ecological Risk Assessment for
Designing and Conducting Ecological Risk Assessments, review
vironmental Response Team.
ntal Protection Agency (EPA). 1995. Draft Proposed Guidelines for
Assessment. Risk Assessment Forum, Washington, D.C., EPA/630/R-
ivironmental Protection Agency (EPA). [Soon to be released.] Superfund Mine Waste
Reference Document. (This document will have an ecological risk assessment chapter
geared towards mining sites, but also an appendix covering the general ecological risk
assessment process.)
84
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
7.2.2 Screening Values
Batts, D. And J. Cubbage. 1995. Summary of Guidelines for Contaminated Freshwajjtf Sediments.
Washington State Department of Ecology. NOTE: This reference has good screening values,
but site-specific data may be more appropriate, as conditions vary. <,; * ^
Screening Benchmarks for Ecological Risk Assessment,^ E;1wironmeritat I
ces and Healfe
Sciences Research Divisions Oak Ridge National LabOjfaory, Oak Rldg^Tei^fessee. NGTJE:
These are "benchmark" values and are useful if othertiiformationjs lacking; tb&ia&sjs f&£ch
value should be critically evaluated before it is used /'' ' '
*
US EPA. January 1996. Ecotox Thresholds. ECO Update$&$* intermittent Bulletin of Office of
Emergency and Remedial Response. NOTE. These-V$tfue$ may not be appropriate in all
situations; particular attention should be given to applicabtfityfasiie conditions.
7.2.3 Uncertainty References ^ rttff*\
Frey, H.C., Quantitative Analysis of Uncertaj^y"ancl,Vdf^MKty in Environmental Policy Making,
American Association for the Advancement of Science, Washington DC. 1992.
Burmaster, D.E. and Anderson, P.D^Principle* of Good Practice for the Use of Monte Carlo
Techniques in Human Health an«l^)logical f?fsk Assessrnents." Risk Analysis, Vol 14, pp. 477-
481, 1994.
Macintosh, JD.L, Suter,
Ecological ftisk Asses;
7.3 Whereto
se of Probabilistic Exposure Models in
ContaminatejSftes," Risk Analysis, Vol 14. pp. 405-419, 1994.
J569-7254). This resource can provide information about how to
vendors. IRIS is also available on PC-compatible diskettes from
National Techrjjjal Information Service, Springfield, VA (703-487-4650). NTIS distributes
many govemjgiprnt publications including EPA documents.
Management Research Laboratory (formerly, CERI), Cincinnati, Ohio (513-
. Depending on availability, NRMRL can provide free single copies of ORD
documents, primarily those identified with EPA/600, and some other documents.
• Superfund Docket (703) 603-8917. Limited source for guidance identified as "OSWER
Directive # XXXXX."
85
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Region 10 EPA Library (206-553-1289). The library will loan EPA publications (and ATSDR
Toxicity Profiles) to the public.
Safe Drinking Water Hotline (800-426-4791). This hotline is staffed frorr^lm to 5:30 pm
EST.
86
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
8.0 REFERENCES
Sigal, L. L. & G. W. Suter II. 1989. Potential Effects of Chemical Agents on Terrestij& Resources.
Environmental Professionals, Vol. 11, pp 376-384.
U.S. Environmental Protection Agency (EPA). 1996. Ecotq/jj^ECO
Volume 3, Number 2. Washington, DC: Office of ^iirgency
Hazardous Site Evaluation Division; Publ. 9345.0-12
U.S. Environmental Protection Agency (EPA). 1995&\Risk
Washington, DC: EPA Administrator March 1995. '
termittent Bulletin,
Respons
°* 5\ 5>
U.S. Environmental Protection Agency (EPA). 1995c£/*f&#/7 Effecti*A$&&$tttent Summary Tables
(HEAST). Office of Solid Waste and Emerger^'R4%5bnse, Office bl'Ernergency and Remedial
Response 9200.6-303. NTIS No. PB91 -| ""
U.S. Environmental Protection Agency
On-line database.
U.S. Environmental Protection Ag
Process for Designing and O
Environmental Respon
-------
EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Framework for Ecological Risk Assessment Washington, DC: Risk Assessment Forum;
EPA/625/3-91/022.
U.S. Environmental Protection Agency (EPA). 1991 a. ; Conducting Remedial
Investigations/Feasibility Studies forCERCLA Municipal Landfill S/tes/Cfftice Of Emergency and
Remedial Response. OSWER Directive No. 9355.3-11.
^v-
U.S. Environmental Protection Agency (EPA). 1991b. Merim
Assessment. Office of Research and Development Office
Assessment. OHEA-E-367.
U.S. Environmental Protection Agency (EPA). 1991c. Rfe£M$$95ment Guidance foTsuperfund,
Volume I, Human Health Evaluation Manual, Part B, D&Y&fofifftent of Risk-based Remediation
Goals. Office of Solid Waste and Emergency Response. OSWEftQirective No. 9285.7-01 B.
U.S. Environmental Protection Agency (EPA). 1991& Hs/c Assessm&M Gwdance for Superfund,
Volume I, Human Health Evaluation Manuakj^£CKj$&kEvaluatfc%jJ!>f Remedial Alternatives.
Office of Solid Waste and Emergency RaspbKse/pSWEl^Directive'No. 9285.7-01 C.
>*^ TȴV
\«^J:ffi^
Baseline Risk Assessment in
and Emergency Response.
U.S. Environmental Protection Agency jjpPA). 1991e.
Superfund Remedy Selection Decisions. Offfce of S
OSWER Directive No. 9355.0-
U.S. Environmental Protection Agj^cy (EPA)^991f. jSjjp'plemental Guidance on Performing Risk
Assessments in Remadijsf^lnvestigs^aa^^a&bility Studies Conducted by Potentially
Respofi$$fcParties.,Qffit& of Solid Wastslid Emergency Response. OSWER Directive No.
nonf- /tffJ'--.; "% i«Si'-'-«% ^rf. "•.vS»i>v
U.S. Environmental Protectior^Ageney^EPA). 1991g. The Role of BTAGs in Ecological
Assessment sJECO Update, Int&emi&fynt Bulletin, Volume 1, Number 1. Washington, DC: Office
of Emerg^ic^'arjd Remedial Response, Hazardous Site Evaluation Division; Publ. 934.0.05I.
U.S. Eiiffronmental Prote^oH^gency (EPA). 1991h. Risk Assessment Guidance for Superfund,
an Health Evaluajjjlfi&fanual, Supplemental Guidance: Standard Default Exposure Factors.
fice of Emergency J|d Remedial Response, Office of Solid Waste and Emergency Response,
Directive No. 9285 JP03.
tivironmen.tap:)rotection Agency (EPA). 1990a. Air Pathway Analysis Procedures for
Ucations. Office of Air Quality Planning and Standards. EPA/450/1-
PD3.004.
U.S. Environmental Protection Agency (EPA). 1990b. Guidance for Data Useability in Risk
Assessment. Office of Emergency and Remedial Response. EPA/540/G-90/008.
U.S. Environmental Protection Agency (EPA). 1990c. Methodology for Assessing Health Risks
88
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
Associated with Indirect Exposure to Combustor Emissions. EPA 600/6-90/003.
U.S. Environmental Protection Agency (EPA). 1990d. National Oil and Hazardqjj&Substances
Pollution Contingency Plan; Final Rule. Federal Register, Vol. 55, No. 46, pa$is 8665-8865.
.Risk
Assessment
Sludge.
U.S. Environmental Protection Agency (EPA). 1989a. Djfaelopr
Methodology for Land Application and Distribution
600/6-89/001.
U.S. Environmental Protection Agency (EPA). 19895.
An Overview. ECO Update, Intermittent Bulletin, Volutm^ltyrnber 2. Washin^fiiJ Office
of Emergency and Remedial Responses, Hazardous Site Evaluation Division; PubL 9345.0.0-5I.
•A •. \s
0'%« s ^ v"
U.S. Environmental Protection Agency (EPA). 1989c. Risk Assessment Guidance for Superfund:
Volume 2 • Environmental Evaluation Manual, Interim Final. Wa$$rl(|9n, DC: Office of Solid
Waste and Emergency Response; EPA/540/t-S^0DtA.
U.S. Environmental Protection Agency (EPA||3989d, Risk Aissessmefit Guidance for Superfund,
Volume I, Human Health Evaluation Mafjjjiil, Part A?B&s$tim*f%9l$*Assessment. Office of Solid
Waste and Emergency Response. glWER Directive N&..S2SS^7-01A. EPA 540/1-89/002.
U.S. Environmental Protection Agen^pl^A). 1J|9e. Eco/gpca/ Assessment of Hazardous Waste
Sites: A Field and Laboratory Rjjjenence. j||rvallis, Q:^.f Office of Research and Development,
Environmental Research^Lal%atory; EHloO/3-8..^ifi3.
U.S. Envirgifinienjal Proti
Directive
(EPAl|||p^ERCM Compliance with Other Laws Manual,
Office'of Emergency and Remedial Response. OSWER
-02. EPA/540/6-89-009.
U.S. Environmental 'Projection Agency (EPA). 1988b. Guidance for Conducting Remedial
Investigatfom'-ktid F&Mtfoility Studies Under CERCLA. Office of Emergency and Remedial
Response. OSWERJSredive No. 9355.3-01.
u.s
vironmental P
ice of Health an
Agency (EPA). 1988c. Estimating Exposures to 2,3,7,8-TCDD.
vironmental Assessment. EPA 600/6-88/005A.
En vironmental Jtection Agency (EPA). 1988d. RfD Description and Use in Health Risk
(ground Document 1A in Integrated Risk Information System (IRIS), on-line
Protection Agency (EPA). 1988e. Superfund Exposure Assessment Manual.
Office of Remedial Response. EPA 540/1-88/001.
U.S. Environmental Protection Agency (EPA). 1988f. Estimating Toxicity of Industrial Chemicals
to Aquatic Organisms Using Structure Activity Relationships. Office of Toxic Substances;
89
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EPA Region 10
DRAFT Supplemental RAGS
March 27,1996
EPA/560/688/001.
U.S. Environmental Protection Agency (EPA). 1986. Risk Assessment Guidelines
of Health and Environmental Assessment. EPA/600/8-87-045. (Alsojgublisl;
Register, September 24, 1986, 55 FR 33992-34054.)
U.S. Environmental Protection Agency, Region III (EP,
Assessment Guidelines. Philadelphia, PA: Hazardous
Program Branch; Publ. 19107-4431.
U.S. Environmental Protection Agency, Region IV (EPA I
Supplemental Guidance to RAGS: Region 4 Bulletins:
Waste Management Division; Bulletin 1.
986. Office
the Federal
U.S. Environmental Protection Agency, Region IV (EPA IV):
Supplemental Guidance to RAGS: Region 4 Bulletip&,'Human Hei
Waste Management Division; Bulletin 2.
U.S. Environmental Protection Agency, Rfcgion
Supplemental Guidance to RAGS: Regjbn 4 Bulk
Waste Management Division; Bu
U.S. Environmental Protection
Supplemental Guidance to RAgS: Regie,
Waste Management Divi«qr|lBulletin
Ecological Ri
ion, Supe
Collection
lth Risk Assessment. Atlanta:
Toxicity Assessment,
ssessment. Atlanta:
b. Exposure Assessment,
Risk Assessment. Atlanta:
IV). 1995d. Risk Characterization,
jman Health Risk Assessment. Atlanta:
ReglcWX (EPA X). 1990. Region 10 Policy, Conduct of
ility Studies. Region 10 Hazardous Waste Division.
U.S. Environme
Evaluati
VanH
_%, Ag^rtcyfejRegion X (EPA X). 199_ RME Guidance. Seattle: Risk
ental Sprvices Division.
. Bensen and C.S. Staley (INEL). 1994. Guidance Manual for
Ecological Risk Assessment of the INEL, draft. Idaho Falls, ID:
Laboratories.
rtment of Ecology. 1991. Model Toxics Control Act Cleanup Regulation.
'AC.
90
-------
Calculation of Human JMfi Ris
(Insert Revised Radionuclide$£>f%jj'Equatiot
trations for Radionuclides
HHEM Part B Update Release)
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-------
ApjfSndfx
Summary TMTof HuJIn HealthyfKposure Factors
(Insert updated Region 10 E^ojjje Factot
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ical Issues
-------
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Office of Environmental Assessment
Region 10
Risk Repor
January 1996
Release Number 1
focus: eeo risk
1&@JF
vsr
ixth Avenue
:e, WA 98101
553-8209.
An intermittent publication of the US EPA Region jjiRisk Emuation
intended as a technical case study illustration to s^f^fthe regional
assessment guidance (Jan 96) and can be nestedl^f^idix C of that document.
(Insert Soil Background Issue Paper)
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-------
l Re/ea^lase Study Summaries
-------
Office of Environmental Assessment
Region 10
January 1996
Release Number 2
fgcus:jito risk
Special Release: Case
An intermittent publication of the US EPA Region /
intended as a technical case study illustration to su
assessment guidance (Jan 96) and can be nestein Ap
luation Unit, this report is
egional Superftind risk
'that document.
(Insert Soil Background Case Study Excerpi
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Office of Environmental Assessment
Region 10
Risk Repo
Special Release: Case S
January 1996
Release Number 3
An intermittent publication of the US EPA Region 1
intended as a technical case study illustration to
assessment guidance (Jan 96) and can be nesti
ImAon Unit, this report is
sgional Superftmd risk
•that document^
(Insert Commencement Bay Tidelands Ecol<
Study)
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Human Health ^Simased|||ncentrati|p5 for Water and Soil
(Attach Region 3 RBC tablesj£ajjKage with
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