United States
           Environmental Protection
           Office of Policy
           Planning, and
'•EPA' 230-B-93-003
September 1993
A Guidebook to
Comparing Risks and Setting
Environmental Priorities




                         ACKNOWL!2I>GMENTS           -
                               -i-         •.              -          '

   Numerous individuals contributed to the preparation of this workbook. First, Debora
Martin, as chief of the Regional and State Planning Branch, has overseen all aspects of the
project. She is also preparing a shorter overview document to accompany this workbook.
Richard Worden was the project coordinator and principal writer of die workbook.
   Debra Gutenson, Steven Keach, and Lawrence Molloy of'the Regional and State
Planning Branch have contributed chapters on building a sound foundation for a compar-
ative risk project, conducting die quality-of-life analysis, and applying die comparative
risk paradigm to international projects, respectively. In addition, many colleagues in die
Regional and State Planning Branch, regional EPA offices, and state government reviewed
drafts of the workbook and provided valuable feedback to us. The assistance of all diese
individuals is gratefully acknowledged.
September 1993



                Section 1: Getting Started
                     1.1 Introduction
                     1.2 Creating a Strong Foundation

                Section 2: Risk Assessment
                     2.1 General Analytical Issues
                     2;2 Assessing Environmental Risks to Human Health
                     2.3 Comparing and Assessing Ecological Risks
                     2.4 Quality-of-Life Assessments
                                        - • I                    -J         .
                Section 3: Risk Management
                    3-1 Risk Management                       '•  '  '    '

                Section 4: SpecialApplications
                    4.1 International Application of the Comparative Risk
                                   ...   i        •    •    •.-...     ..      •  .
               Section 5: Appendices      •  \                    \  '
                    Appendix 1: Revised Core List of Environmental Problem Areas
                       for Regional Comparative Risk Projects
                    Appendix 2: Comparative Risk Contacts and Rewources
September 1993





                                                                        1.1 Introduction
          All environmental problems pose various types and degrees of risk to human
          health, to ecological systems, and to society's quality of life. Federal, state, and
          local government officials have found comparative risk to be a powerful manage-
  ment tool that helps them determine how to best allocate limited resources for reducing or
  preventing these risks.
     Comparative, risk is both an analytical process and a set of methods;  used to systemati-
  cally measure, compare, and rank environmental problems. Besides helping managers
  identify the worst environmental problems—or the greatest risks—in their areas, compar-
  ative risk provides a common basis for evaluating the net benefits and costs of different
  strategies for reducing or preventing those risks. Thus, comparative risk rankings can pro-
  vide an important input to the priority-setting and budget processes when possible risk
  reduction and prevention strategies are considered in the context of other relevant non-
  risk concerns, such as  economic viability, technological feasibility, and social equity.
    With the assistance of staff from the Environmental Protection Agency's Regional and
  State .Planning Branch, comparative risk projects have been- or are being conducted by
  over 20 states, several  Native American tribes, and nearly a dozen localities. The compara-
  tive risk approach has  also been applied in Bangkok, Thailand, Quito, Ecuador, and
  Tetouen, Morocco, arid in other cities around rlie world, with assistance from the Agency
  for International Development.              !
    This workbook provides guidance to those planning or participating in comparative
  risk projects. It discusses the major technical and managerial issues inherent in compara-
  tive risk projects; explains the mechanics of con ducting the risk analysis and risk manage-
  ment phases of a project; and describes the international application of the comparative
  risk framework. As existing methods, data sources, and processes are adjusted or created in <
 response to new applications of comparative risk, such as for urban or tribal projects, sup-
 plemental chapters will be periodically added to this workboojk. These updates will be
 announced in the  monthly bulletins of the Western and Northeast Centers for
 Comparative Risk and can be requested by anyone seeking them. They can also be
 obtained from the Regional and State Planning Branch office at EPA Headquarters in
 Washington, D.C
   In addition to this document, for those seeking advice or insights from others.who have  ,
 already conducted comparative  risk projects, Appendix 2 of this document lists contacts
 and reference materials. Discussing questions or problems with others who have experi-
 ence with the comparative risk process can be very useful in getting projects started suc-
 cessfully and keeping them running smoothly.  !
September 1993


 Initiating a Comparative Risk Project 		'..-	...;...		3

 Building the Comparative Risk Project Team  .,			..4
      Project Manager	,	....:	.6
         Role	;.......	...1...,	i.........	:......6
         Support		6
         Responsibilities...	i..;	..	6
      Steering Committee	....;	7
         Role	..	..I	1..............	7
         Members  ..	L......:	'„	7.
         Responsibilities.;	\	,......;	,..„...	7
      Public Advisory Committee	!,	.....7
         Role			„.......„	„...„.......7
        Members	;.„	:.'...,..	...8
        Responsibilities	..'.	8
      Technical Work Groups	...;...„.•	........8
        Role......	;	......8
        Members	,!.	....g
        Responsibilities	...,1	,.	....9

Organizing the WorkGroups  .........;..........,:...	9
      ByRiskType.	............I..........	.......;	......9
      By Media  ........'.	......;.....9
      Single, Combined Work Group			10
September 1993                             ;                                    1.2-1

A Guustoooi to Comparing Risks anJ Setting Environmental Priorities
Targeting Available Resources	10
     EPA's Regional/Scare Planning Branch	1°
     EPA's Regional Offices	,	••••10
     Comparative Risk Centers	•	• •	11

Initiating Activities Simultaneously	11
     Project Planning and Start-up	H
     Risk Analysis 	•	•	•	•	12
     Risk Management	.........12
     Project Wrap-up	•	,...12

   1.2.1  Key Organizational Units and Responsibilities of the
         Comparative Risk ProjectTeam	.........5

   1.2.1  Pote'ntial Stakeholders of a Comparative Risk Project Team	 3
   1.2.2  Typical Kickoff Meeting Topics	••••••	••••••	5
 12-2                                                                September 1993

                                                        1.2 Cmiting a Strong Foundation
        The comparative risk process should be viewed as a whole, from data collection,
        analysis, and risk ranking to developing an action plan and implementing new
        strategies for reducing risk. Each comparative risk project is challenged to own the
 process, determine in advance how the information and rankings will be used, and deter-
 mine how change can be initiated. The process; is very labor intensive and politically
 charged. Because the investment of time and money is substantial, careful planning for the
 whole process is essential.             '     i

    This chapter presents suggestions for planning a comparative risk project from begin-
 ning to end—setting goals, determining stakeholders, structuring the project, describing
 different external resources that are available, and highlighting a few issues that are impor-
 tant when getting started. The chapter ends wkh a list of activities for consideration from
 start-up to completion of a project.          ;


   Most of the comparative risk projects to date have been initiated wilhin state govern-
 ment, usually within the environmental protection/natural resource or health agencies. A
 few'projects have sprung from the interest of environmental and business leaders; this
 trend will become more common as comparative risk becomes better known across the
 country. In either case, the initiator will find it useful to plan the process with a few of the
 key players or "stakeholders"; this group is referred to here as the project planning team •
 Potential stakeholders that might be considered as pan of a comparative risk project team
 are listed in Exhibit 1.2.1.                  ''•        •               -'.'",'  ~ .

                               Exhibit 1.2.1:                 V
      Potential Stakeholders  of a Comparative Risk Project Team
    • Governpr's office
    • State agencies
     Department of Environmental
     Health Department
     Natural Resources Department
     Fish and Wildlife
     Energy Department
     Education Department
     Land Use Commission
Major business interests
Environmental advocates
Chamber Of Commerce
   Some preliminary steps for the planning team are:

   •  Define the underlying problems (e.g., budget crisis, crumbling political consensus
     on priorities, possible mismatch of resources and needs, lack of clear mission or
     cooperation within and across organizations).
September 1993

 Guidebook u> Comparing Risks aruL Setting Environmental Priorities
  * Set goals for the project. Most project goals include making significant improve-
    ments in the policies. Meeting these political challenges should influence all other
    decisions about the project state's environmental management programs, including
    changes in priorities, budgets, arid .    •                                        ,
  • Identify the individuals needed to achieve those goals, and create the comparative
    risk team. The team typically consists of a project director, steering and/or public
    advisory committees, and technical committees.
  • Write a work plan. A work plan is one of the first products developed once the pro-
    jects goals and objectives are identified. It should include the project's structure,.
    budget, and methods.
  • Develop ground rules; select analytical criteria and methods for assessing problem
    areas. The planning team may propose some ground rules, but typically the steer-
    ing/public advisory committee(s) want to develop the ground rules. The technical
    committees are best suited to grapple with analytical criteria  and methodological
    issues. They will have to decide which of the standard methods they will use and
    where they will try to innovate.         '                      ,            .
  • Initiate the project with a kickoff meeting for the comparative risk team. After the
    initial planning and organizing, it is important to get the various committees started
    with enthusiasm and a shared sense of mission. Most states have found that assem-
    bling the participants off site (away from interrupting telephones and meetings) in a
    desirable and  quiet location for at least two days has helped build a sense of mission
     and teamwork and a common understanding of the project ahead. Topics that are
     typically discussed in a kickoff meeting are indicated in Exhibit 1.2.2:
  The planning team may need to repeat these steps several times before it will have
assembled the correct group to set the project's final goals and objectives. At some point,
the team may need to decide to push the project forward even  though there may not be
unanimous agreement on the project. There always will be skeptics or those resisting
change. A key role of the planning team in the beginning is finding the right balance
between building a strong foundation and knowing when to move on.

   There is no one right way to structure a comparative risk project. The types of commit-
tees and their roles and responsibilities will reflect the institutional and  political realities in
each state.
   Though many variations are possible, the key organizational units and their responsibil-
ities are shown in Table 1.2.1. These responsibilities are considered key because they rep-
resent basic functions that a person or committee should be responsible for in every cpm-
parative risk project. The .members of these committees may need to change  during the
project to meet the changing technical and political challenges inherent in moving from
an analysis of risks to the development and implementation of risk management strategies.
Planners should determine these changes in advance. For example, the  public advisory

, 2_4                                                              September 1993

                                                      1.2 Crtating a Strong Foundation
 committee for the first phase (risk assessment) may be entirely comprised of interest group
 representatives, while in the second phase (risk management) it may be entirely comprised
 of legislators or state planners. However, most: projects have maintained at least some con-
 tinuity of membership (and, hence, ownership) in moving from, the risk assessment to the
 risk management phase.                               - ~ '   '  . > .

       .                Typical Kickoff Meeting Topics
     • General background on purpose amd goals of project

     • Introduction of participants     -

     • A ranking exercise--an opportunity to "get dirty" with the process

     • Basic operational ground rules

     • Basic training on how to conduct a human health, ecological, and
         quality-of-life comparative risk analyses            /
                     ,                - -,                  • '•
     • Risk communication principles   i

     • Vision of the project results                .

     • Trouble shooting (Are all of the key stakeholders included in
         the project team? Does the proposed schedule mesh with timing
         requirements of the legislature? Etc.)            ,
                               Table 1.2.1:
      Key Organizational Units and Responsibilities of the Comparative
                           Risk Project Team
Organizational Units
Project Manager
Steering Committee
Public Advisory
Technical Work Groups
Supervises all aspects of the project.
Provides overall direction of the project
Ensures public participation in the process, and
ensures the project's work remains understandable,
relevant, and credible to the public.
Perform data collection, data analysis, and
preliminary rankings.
September 1993

A CuuUbook to Comparing Risk] and Setting Environmental Priorities
   Similarly, decisions such as who has ultimate responsibility for the final ranking of risks  -
will also vary. Some states have chosen to give this responsibility to the senior managers
(Steering Committee), while others have placed it with the Public Advisory Committee.
Still another state created an Integrated Ranking Subcommittee, made up of three mem-
bcrs from each technical work group, who had responsibility for developing a final inte-
grated ranking of all problem areas/The key to success is making explicit decisions in the
planning stage and then remaining flexible.
   The functions and membership of the various committees can also be recombined in
several ways. One project effectively merged the Steering and Public Advisory
Committees. Another merged many of the functions of the Technical and Public Advisory
Committees (with unknown results). While the four pilot projects in Colorado,
Washington, Vermont, and Louisiana were managed directly by state government, some of
the new projects are creating hybrid management structures with acadcmia and consulting
agencies. The complexity of these hybrids demands, particular attention early in the
process to defining clear roles, responsibilities, and expectations for turning phase one
analysis into phase two action.                             .
   These ideas represent the best of what has worked so far, but each state project is
unique. It is crucial to consider the roles, functions, and responsibilities that have been
described and then to decide what arrangement will work best in each situation.
   Major characteristics of the key organizational units from Table 1.2.1 arc discussed in
 more detail below.

 Project Manager                   >
 Role                                                              '  '
   The project manager choreographs all aspects of the project, is  responsible for day-to-
 day management of the project, and is trie principal contact with  regional and
 Headquarters EPA, All state project manager positions to date have been fiJl time.
 Support            ,                                                ,
   The project manager needs several types of support. Direct access to senior government
 officials (e.g., secretary of Department of Natural Resources or Department of
 Environmental Quality) and the support and commitment of senior managers widiin the.
 sponsoring organization are critical. The project director will also need stafFsupport as
 well as administrative support.                                      v               '
 Responsibilities                                                        r   u •  i
    The project manager maintains overall intellectual consistency and quality of technical
 analysis; may need to help direct research and edit technical reports; motivates committees
 and clarifies their options and responsibilities; and selects and directs consultants. He/she
 is responsible for ensuring that any necessary training is provided for project participants,
 including risk assessment, risk communication, and introduction to comparative risk
 training. The project manager helps ensure the project's transition from the risk assess-
 ment phase to the risk management. Responsibility for producing the comparative risk

                                                "  ~~        ~September 1993

                                                          ;_2 Creating. A Strory Foundation
 project report, which summarizes the risk assessment portion of the piroject; and other
 reports summarizing the action agenda or risk management phase of the project, resides
 with the project manager. He/she is heavily involved in "spreading the word" about the
 project. This may involve talking to the press and local civic and community groups, and
 writing speeches and articles. (For example, Colorado has developed a slide show to
 explain to citizens what the project was about and its results.) Other states have published
 newsletters to keep state employees up to date and involved. The project manager typically
 needs a variety of skills (e.g., writing and public speaking), a thorough understanding of
 state politics and the environment, and a strong sense of follow-through.

 Steering Committee      -
   The steering committee provides overall guidance of the project and is involved in set-
 ting the goals and objectives. The steering committee may also be responsible for ground
 rules, major decisions, and final rankings.
   The steering committee is usually composed of directors or designees from all partici-
 pating agencies, institutions, etc.; representatives from the governor's office; the chief or
 his/her designee from the Regional and State Planning Branch, EPA; and a representative
 from the EPA regional office. Major constituents to consider could include staff in envi-
 ronmental protection and natural resources, agriculture, housing, education, economic
 development, and transportation offices.                          |
 Responsibilities                          ;                 '   ...
   The steering committee is ultimately responsible for the final rankings; They must
 obtain top management support to ensure enthusiastic participation ai: the staff level
 They may be responsible for staff-hiring decisions and for building the technical work
 group members' responsibilities into job descriptions and performance evaluations. The
 steering committee is responsible for keeping the governor and other political leaders
 informed about and committed to the project. They are also responsible for setting the
 goals and objectives for the project, and for maintaining the organizational commitment
 to develop and  implement the improved risk management decisions or budget changes.- It ,
 is critical to engage the steering committee early in the process to ensure their support for
 the implementation phase; their involvement and support during this phase is essential to
 achieve project  goals.                       :

 Public Advisory Committee
.Role, •   .'      _ '     '   ,    •       ..'•:;      -.  "          '!•'.;•'.;'
   The public advisory committee is the key liaison between the government participants
 and the general public and major interest groups.  It provides a forum far the essential two-
way communication about risk and public values.         •                      f   '
September 1993                                                             1.2-7

A Guukboak u Comparing Raks ami Setting Emnromnfnml Priorities
   Committee members should be broadly representative of the state's regions, occupa-
tions, and interests. They should be known for working well with others to achieve com-
mon goals, not for being obstructionists. Typical members include state legislators, farm-
ers, business leaders, academics, students, environmentalists, and representatives from
minorities, tribes, and existing community networks.                      .     .

Responsibilities                                                        -i.cn
   Some projects have successfully empowered the public advisory committee with hill
decision-making control over many major issues, such as defining an environmental vision
for the state, selecting the set of problem areas, reviewing technical work groups' data and
conclusions, and ranking the problems and recommending priorities., They have done this.
to ensure that the results do not become overly "politicized" and associated with a particu-
lar administration. The committee can also Serve as an important source of continuity and
commitment if elected or appointed officials change during the process.      '
   One of the distinguishing features of the comparative risk process is that it allows for
strong public participation. For those projects where involving the public is critical to .
accomplishing the goals and objectives, the initial planning should include a framework
 for involving public-interest groups, the general public, or the press. If details remain for
developing and implementing a complete public-involvement strategy, then these issues
 should be addressed early in the process. How the public is involved is a specific matter for
 each project to decide for itself. Projects may involve the public early and often, soliciting
 their input on the problem areas to be studied, weighing public values, the appropriate
 ranking of risks, and action steps to reduce risks. On the other hand, the public advisory
 committee may be selected to represent the public during the risk assessment phase of the
 project, followed by public involvement through meetings or an environmental summit to
 share the rankings and solicit ideas for the risk management priorities for action.
 Whatever combination of events is decided, the important point is to involve the public
 and key stakeholders.

  Technical Work Groups

    During the analysis phase of comparative risk, the technical work groups collect data;
  analyze the risks to health, ecology, and quality of life and typically perform a preliminary
  risk ranking. In the risk management phase of the process, the work groups may develop
  and analyze a broad variety of strategies to improve the functioning of government, reduce
  risks, or reduce costs.
  Members '                                                          ...
    The members of the technical work groups are typically experts from participating state
  agencies or they may be recommended by senior state agency staff. Work group member-
  ship maybe augmented with other well-known outside experts, academicians, etc Each
  technical work group should have a chairperson who is responsible for coordinating with
  the other work groups and ensuring the consistency and integrity of the approach, keeping

  	'	        ~~~           ;               September 1993
   1.2-8                •

                                                         1.2 Creating n Strong Foundation
the project manager informed of progress and unresolved issues, and ensuring that prob-
lem-area reports are completed on time.  _   '                    . !
   Technical work group members may play a key role in defining th« analytical methods
to be used in the analysis, including selecting evaluation criteria, hanclling uncertainty, and
presenting information. These roles will demand considerable judgment in addition to
purely analytical skills. These issues should be addressed before and during the analysis,
and may be reviewed and discussed with the steering committee.
   For each problem area, technical work groups develop plans of approach which briefly
describe data sources, the chosen'analytic approach (quantitative or non-quantitative), and
major sources of uncertainty. They then conduct the analysis and write the problem-area
report describing in detail the risk or damage estimates with discussions of analytic tech- .
niques, major assumptions, and sources and implications of the uncertainties imbedded in
the analysis. Finally, workgroup members may develop preliminary or "straw"  rankings
and present these to die steering committee or public advisory committee.

   Because the technical tasks of a comparative risk project are so challenging, it is essen-
tial that projects create strong work groups wkh no weak links or reluctant participants.
One state succeeded in building excellent technical teams by holding i competition for
membership. Possible ways to structure the technical work groups are by risk type, by
media, or by combining them into one large work group.                          ' '
                                         i.. ' '    . .  '           'I.  .   '  •'      ' '
By Risk  Type                                               ;      .
   Forming work groups according to risk type (human health, ecological, and quality of
life) has several advantages. The first and perhaps most important is that this encourages
communication among media offices, and begins to develop a multimedia orientation.
Second, all work group members will become familiar with the data, analysis, and issues of
all problem areas. This helps ensure a more balanced approach to the final rankings and is
also a benefit to die individual members as they broaden their understanding of other
areas.  "•               .       •   .       i          .        •-...-

By Media                              /
   Technical work groups can also be organized by media type (air, waiter, waste, toxics; or
air, water, land, natural resources). This organization is appealing at first glance, since
many agencies are organized this way. However, it doesn't encourage work group members
to think in an integrated framework across programs and media, and there is a natural
tendency for air members to rank air problem!! highest, water membeirs to rank water
problems highest, etc               .   •   j '                        .              '
September 1993

 A Guiaebook to Comparing RisJes ami Setting Environmental Priorities
 Single, Combined Work Group
   A third option involves forming one large technical work group that does all three types
 of risk analysis (health, ecological, and quality of life). This structure may be useful where
 there isn't enough staff to form three separate work groups. However, this structure places
 a heavier workload on each work group member, and one or more risk types may not be
 treated fairly.

   An ever-growing number of states, as well as all 10 EPA regions, have already complet-
 ed comparative risk projects. Thus, states initiating a comparative risk project can draw on
 the experiences of these groups. In addition, other resources are available to assist those
 undertaking a comparative risk project. EPA's Regional and State Planning Branch, EPA's
 regional offices, and the Comparative Risk Centers offer expertise and technical guidance.

 EPA's Regional/State Planning Branch
   Regional and State Planning Branch (RSPB) at EPA Headquarters provides funding for
 each state's comparative risk project through a cooperative agreement. How these resources
 are to be spent is developed in the work plan and approved by RSPB, with concurrence by
 the regional office. Previously, states have used some of these resources to hire contractors
 or consultants to augment expertise within the state agencies. These may be contractors
 with previous comparative risk experience, or local experts or academicians familiar with
 each state's specific problems.                                    '
   AstafFperson is usually assigned to each comparative risk project to provide technical
 assistance. This includes offering additional "guidance on any of the issues discussed in this
 document, such as explaining how a state project fits in with EPA's planning and why this
 link is so important; briefing senior managers and/or staff on the project and relaying EPA
 Headquarters' response and perspective; recommending experts, or contacts in other
 states, for specific problems; suggesting the use of facilitators or mediators who have suc-
• cessfully led other states' meetings; and general brainstorming and problem solving. RSPB
 staff can also provide basic training that may be useful for work group members  and  assist
 in planning kickoff meetings and workshops.                    ,   ,

 EPA's Regional Offices
   The EPA regional contacts can be an invaluable source of information and assistance.
 Those who have completed comparative risk projects can relate direct experience and pro-
 vide detailed guidance and specific data. Also, any proposed changes in EPA funding of
 state programs that may occur as a result of this planning must be negotiated through the
 EPA regional office (although the amount of federal dollars will vary from state to state).
 It is therefore important to develop good communication with the region early in the pro-
 ject to ensure general agreement on major ground rules, analytic techniques, problem area
 definitions, etc.
  1.2-10                                                            September 1993

                                                        . 1.2 Creating a Strong Foundation
 Comparative Risk Centers
   The comparative risk centers are staffed by a few former directors of state comparative
 risk projects and are funded by EPA (Office bif Policy Planning and Evaluation), The cen-
 ters provide technical assistance on comparative risk projects; they function as clearing-
 houses, providing information on what other istates and regions are doing and gathering
 data from within EPA and other sources; they develop and conduct training courses for
 state project participants; and they also assist in technology transfer by hosting national
 meetings for state comparative risk participants.
   At present,.there arc two comparative risk centers:
      Northeast Center for Comparative Risk                       .
        Vermont Law School
        PO. Box 96; Chelsea Street
        South Royalton, VT 05068                              !
        Ph. 802 763-8383;  Fax 802 763-2920
     Western Center for Comparative Risk
        P.O. Box7576                   ^:                     j            .   -
        Boulder, CO 80306
        Ph. 303 494-6393; Fax 303 499-8340

   Although the process described in this chapter is presented "from start to finish,"in
 many respects it is not a linear process. Several activities may be occurring simultaneously,
 and many issues may need to be revisited or revised during the project.

 Project Planning and Start-up                            i
   • Assemble planning team
   • Assess underlying problems
   • Define goals for the project            ^                     j
   • Secure support of key stakeholders
 :  • Secure letter of support from the governor
   • Select project director             .    !
   • Determine organizational structure     !                     ';.-.'
   • Select technical work groups and public advisory and steering committees
   • Determine public-participation role    ;
                               .         - *     '         .       ''         ••
   • Determine ranking process and who is responsible for each ranking
   • Determine process to turn ranking results into risk reduction strategies/budget
     decisions           •            • .  \                     ,
                     _,•'-•             i            •         ,:
   • Begin identifying and defining problem areas                 '
        .-      -.'•••        '       "     ' *•                '!.••,'•,•
September 1993                          |                                 1.2-11

A Guidebook to Comparing Risks and Setting Environmental Priorities
Risk Analysis
   •  Finalize problem-area list and definitions
   •  Gather data
   •  Assess risks for each problem area
   *  Prioritize risks by ranking them
   •  Document risk analysis
   •  Identify areas of uncertainty requiring more research/data
   •  Identify environmental indicators that will help monitor risks in the future

Risk Management                                                        •
   •  Select risk management factors
   •  Determine risk reduction goals for problem areas                       '     .
   •  .Brainstorm on activities to reduce risk for problem areas
   •  Consider barriers to implementing activities
   •  Develop actions to overcome barriers
   •  Propose action plan—activities to reduce or prevent risk, a schedule, measures of
   •  Document action plans                                .       :
   •  Establish process for repeating project or updating results

Project Wrap-up
   Evaluate the successes  and failures of the process for improvements in the next cycl
the process doesn't stop at the end of the project, but should be a foundation for years of
incremental change and a more thorough  understanding of the problems.
September 1993



                                                        * -<•   \
                 2.1 GENERAL ANALYTICAL ISSUES
Defining the Goals of the Project	3
     Characterize All Risks Associated With Each Problem Area	3
     Be Consistent  —	..,	.......:	4
     Be Explicit	:...	.:'.	•.	4
     Distinguish Risk Analysis From Risk Management  	..	5
                                     x  ' ' :                      '
Addressing Environmental Equity Issues  .........—	5
     During the Project Planning and Start-up Phase	;,	5
     During the Problem-Area Identification and Definition Phase	6
     During the Risk Analysis and Ranking Phase	..6'
     During the Risk Management Phase...:	..v	6

Defining the Scope of the Project	..........;	:.6
                          • "          ,     '              .,,.•.             , ^
Assessing Residual Risks  ...*....'..	...:	,	1
     Human Health Risks..	—...........	•••••••	-••• ••••••	7
     Ecological Risks  	'...i	7
     Risks to the Quality of Life  	.....,;......;.....	....;....'.	......8
                                          r        '        "',.',         " •
Assessing Future Risks	—	8

Addressing Transboundary Effects	.-.i	...;...!...'..........	.....9
     Risks  Imported From Other Areas	v	.....10
     Risks  Exported to Other Areas   	,L.........;....,...	.10
     Transbouhdary Effects on Migratory Species	10
September 1993

A Guidebook to Comparing Risks ami Setting Environmental Priorities
Developing a Problem-Area List	• •	"...	11
     Desirable Characteristics	—... 12
     Alternative Approaches for Defining Problem .Areas	..14
        Along Programmatic Lines	;	 14
        By Source Type	•'	:	• —	15
        By Pollutants orStressors	 —	•••• —	15
        By Affected Resource	•	....16
        By Geographic Area	•••••	,	•	•	17
        By Economic Sector  	— • •	,• — •	•	17
        Combining Different Approaches	....18

Agreeing on Risk Ranking Methods and Processes	.........19
     The Importance of Criteria	•	•	...19
     Rankings as Analytical Summaries	•	• • •	•-20
     What the Rankings Mean—Risks v. Priorities	'.	......20
     Ranking Methods	•.•••:	."..21
        Negotiated Consensus	• • •	21
        Voting	••	..22
        Formulas	•	23
        Other Approaches	26
     Criteria for Choosing a Ranking Method	..27
     Presentation Aids	•	•	•••.	28
     Individual or Combined Rankings	29

   2.1.1  Sample Problem Areas Defined Along Programmatic Lines	 14
   2.1.2  Sample Problem Areas Defined by Source Type	15
   2.1.3  Relationship Between the Source and Fate of Stressors	.........19

   2.1.1  Sample Pollutants and Stressors	16
   2.1.2  Samples of Affected Resources	....."..	•••••	16
   2.1.3  Sample Geographic Areas	17
   2.1.4  Sample Economic Sectors	;	.-	•	18
   2.1.5  EPA Region VI Ecological Risk Index Formula....		25
   2.1.6  Filtering/Detoxifying Scale for Degree oflmpact	...26
   2.1.7  Probabilities of Different Degree-of-Impact Estimates	..........26
   2.1.8  Example of Two-Criteria Ecological Matrix :	..29

REFERENCES	:..	.,	•	3i
2.1-2       '                                   "                     September 1993

                                                             2.1 General Analytical ftnies
        There is no single "correct" way to conduct a comparative risk project. Many
        approaches are workable, and each project should choose an approach that is
        uniquely adapted to its own political, institutional, and natural environments.
However, regardless of which approach is taken, there are a number of important analyti-
cal issues and ground rules that should be resolved before beginning a comparative risk
project/These include defining the organizational scope and analytics] goals of the pro-
ject, identifying the problem areas to be analyzed, determining the temporal and geo-
graphic scales for the analysis, and establishing methods and procedures for ranking prob-
lem areas according to the risks they pose.                     .
  This section discusses the advantages and disadvantages of various approaches to these
issues, and makes  recommendations based on past experiences. The decisions made con-
cerning these issues will shape how the analysis is  conducted and how the results can be
interpreted and used. This section may therefore be of particular interest to project direc-
tors responsible for designing, directing, or implementing the project.

  Project participants should strive to achieve a number of analytical goals aimed at
ensuring a fair and open process. The following goals are suggested based on past experi-
ence with other projects:                   .;    •    .  '

Characterize AM Ri$k$ Associated With Each Problem Area
  Typically, risks  are estimated quantitatively for only a portion of a problem area. The
extent of the risks not encompassed in a quantitative analysis should be characterized or
estimated non-quantitatively. This can be done by extrapolating die estimated risks from
the portion of the problem area analyzed to the rest of the problem area. Or, conversely,
risk estimates from larger studies, such as national air modeling studies, can be interpolat-
ed to the study area. Using information in this way can introduce moire potential for error,
which should be acknowledged, but it does allow the magnitude of risks to be estimated
so that problem areas can be ranked into broad categories of high, medium, and low risks.
  For example, there are hundreds of different toxic air chemicals in die atmosphere. In a
typical comparative risk project, risk estimates would be developed fbir perhaps a dozen of
the more common "air toxins." Analysts typically have to estimate whether this sample
constitutes a large or small fraction of die total risk associated widi die enure problem
area. At the very .least, the potential risks from the unanalyzed portion, of die problem area
should be described to risk managers so that their judgments about die risks are better
informed, even if the magnitude of risk cannot be quantified or estimated. Decision mak-
ers may have to use their best professional judgment to adjust die assessment of an envi-
ronmental problem to represent all the risks for that problem.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
Be Consistent
   To compare and rank the risks posed by different environmental problems, participants
in a comparative risk project need, to operate under a consistent set of definitions and ana-
lytical rules. For example, if individuals working on the project do not work with com-
mon definitions of the problem areas to be analyzed, then their ability to produce compa-
rable  results will be greatly diminished. Using different assumptions about exposure (e.g.,
assuming worst-case v. reasonable-case exposures) can also diminish comparability.
Whenever it is not practical to characterize risks across problem areas consistently, dien it
is very important to warn those responsible for ranking problem areas of the potential
effects on the results.

   Comparative risk projects should be as explicit as possible about definitions, methods,
data sources and gaps, assumptions, participants, and procedures. Reports should contain
information about the structure, procedures, and membership of the project, although
some of the technical information might be contained in.technical appendices. Any pub-
lished reports should also explain the rationale behind decisions as well as the decisions
   Setting out assumptions can have several important advantages, such as:
   •   Helping current and future users and reviewers to better understand the strengths
      and weaknesses of the analysis.
   •   Creating a greater degree of trust among the public and affected special interests who
      are evaluating the analysis and the priorities developed from the analysis.
   •   Identifying gaps in existing data and areas where improved data are needed.
   Conducting a comparative risk project highlights gaps in knowledge and data that deci-
sion makers must grapple with as they rank problem areas. Often, information that would,
be useful and desirable for assessing risks will not be available, or at best, it will be difficult
to use in many cases. It is therefore necessary to use best professional judgment to comple-
ment the limited amount of hard data available. How this best professional judgment is
introduced in the risk assessment and management process is extremely important. If it is
introduced into the process in an unstructured way without reference to any supporting
argument or experience, it can bias the outcome. This problem can be countered by hav-
ing broad representation in the membership of the work groups and ranking committees.
Good documentation of data gaps, assumptions, and use of judgment will aid in commu-
nicating the results of the project and translating them into action. Those reviewing and
evaluating the findings of a project will have to accept the process used to reach them. If
they do not accept the process, they will be unlikely to accept the product or conclusions.
This  type of thorough documentation can be of tremendous assistance in building trust
and understanding among project participants, and between project participants and the
general public. Comparative risk projects also provide an excellent opportunity to identify
such  gaps across the  entire organization and to establish a priority list of research or data

2.1-4                 '                                             September 1993

                                                             2.1 General Analytical Issues
needs for the future. In some cases, new data should be collected; in other instances sim-
ply changing the way existing data is collected or stored may be adequate.
            '                    «.         , •              ,      i      '       .
Distinguish Risk Analysis From Risk Management
   While the relative ranking of a problem area is a key factor in sctting.environmemal
priorities, it is critical for project participants 1:0 understand that the risk rankings do not
necessarily represent environmental priorities. Risk assessment asks the question, "What
are the risks associated with different problem areas?" whereas risk management asks, the
question, "What solutions can be found to reduce the risks associated with different prob-
lem areas?" Risk management concerns need to be distinguished from estimates of the
magnitude and nature of risks.                       l
   The aim of the risk assessment process is to evaluate and rank the relative magnitude of
risks associated with problem areas on the basis of the best available scientific information,
and judgment. The risk-based rankings then serve as a key input to the risk management
process in which a number of relevant non-risk factors (e.g., controllability of risks, legal
mandates, public opinion, costs, etc) are integrated with the risk ranldngs to set environ-
mental priorities and select appropriate risk management strategies.

   Environmental equity has grown out of the concern that some low-income and minori-
ty communities are sometimes exposed to higher risks than other groups in society. Low-
income and minority groups often live in polluted industrial areas where they may be
exposed to multiple sources of risk. They also may not have the same access to health care
services, making them more vulnerable to adverse health effects. For example, there are
dramatic differences in the death rates, life expectancy, and disease rates of African,
Hispanic, Asian, and Native Americans compared to the rates for Caucasian Americans. It
is unclear how the combination of economic, social, cultural, biological, and environmen-
tal variables contributes to these disparities. However,  the most important variables appear
to be where one lives and their choice of life style (e.g., how much time they spend out-
doors or what they eat).                                       -
   In addition to the concern about low-income and minority groups, there may also.be
disproportionate risks borne by .women, children, the elderly, and future generations. Each
of these groups can be considered in a comparative risk project. By considering the special
environmental conditions affecting specific populations and their unique vulnerabilities to
environmental stresses, managers can implement efforts designed to protect them more
effectively. Such consideration can be given to these issues during eveiy phase of a compar-
ative risk project.                                          .

During the Project Planning and Start-up Phase
   Projects can be dramatically improved if they are inclusive of the full diversity of soci-
ety. Since minorities are underrepresented in many federal and state environmental organi-
zations and among public-interest environmental groups, it may be necessary to enlist the

September 1993                          i                     i              2.1-5

A Guidebook to Comparing Risks and Setting Environmental Priorities
help of community groups, churches, and/or tenant organizations. During the planning
and start-up phases of a project, many decisions are made .that will frame the project and   ,
set the direction for how it is conducted. Therefore, it is very important that full participa-
tion occur from die very outset of the project, including the planning and start-up phases,
and continue diroughout die entire project. Early involvement in the project by all groups
is likely to pay off at the end of the project in terms of broad-based public support to over-
come any resistance to implementing the results of die project.       -   •..'

During the Problem-Area Identification and Definition Phase
   Specific population groups that might be at higher risk can be identified in die prob-
lem-area identification and definition phase of a project.  For example, the exposure of
migrant farm workers to a multitude of pesticides may pose different and significant risks
from  risks posed to the general population. This may warrant creating a new problem
area, or at least conducting a specific sublevel analysis of occupational exposure to pesti-
cides  within the larger pesticide problem area.                         •' , .    .

During the Risk Analysis and Ranking Phase
   Differences in cultural behaviors, activity patterns, and food preferences among ethnic
and racial groups can be analyzed, and may have implications during die ranking phase of
a comparative risk project. For example, natural resource degradation can also directly
have an impact on poor populations who traditionally supplement their diets by eating
fish caught in possibly contaminated local waters. Different cultural values and norms can
also affect how the quality-of-life analysis is conducted and which criteria are selected. For,
example, urban poor are likely to be more interested  in enhancements to their immediate
environment (e.g., urban  parks and cleanup of abandoned industrial plants) than in pre-
serving biodiversity or pristine natural resources in far-away places.

During the Risk Management Phase
   This phase of a comparative risk project deals with die issues of what can and should be
done about the environmental problems that were identified, analyzed, and ranked during
previous phases of the project. Risk management strategies can be developed and imple-
mented to address risks of particular concern to specific population groups. For instance,
in some cases, due to their'small population numbers in relation to the overall population,
risks  to specific groups (e.g., high exposures to pesticides among Hispanic migrant farm'
workers) are overshadowed by less severe risks to a larger number of people. Specifying
 early in the project that risks to specific populations will be explicidy analyzed, and that
 individual risk estimates (v. population risk estimates) will be considered in die risk man-
 agement process, can help ensure that equitable actions are taken.

    One of the first issues to be decided that will frame the overall analytic approach of die
 project is: Which environmental problems should be analyzed and which ones left out?

 2 i-
                                                               2.1 General Analytical luues
  How far should the analysis venture into domains traditionally regulated by other health
  or natural-rcsource-management agencies? Should global problems be included in the
 , analysis even though they are beyond the organization's ability to control them? In general,
  it is recommended that comparative risk projects be defined broadly to encompass all
  environmental issues and to capture potential future risks as well as current risks.
 .   For the most part, comparative risk projects to date have combined analysis of tradi-
  tional environmental problems (air and water pollution, waste, pesticides and other toxics,
  etc.) with other environmental issues where the authority to manage the problem is out-
  side their purview (e.g., occupational exposures to toxic chemicals, land-use .issues perti-
  nent to habitat protection, and indoor ak pollution). Projects that are more comprehen-
.  sive typically require a greater degree of involvement by other relevant federal, state,
  and/or private organizations. This participation has contributed toward more cooperative
 working relationships among public agencies and between the private and public sectors.
                                          '"                     I
    In  comparative risk projects, risk assessments are performed on this risks that exist,
 given the efforts of public and private organizations to. eliminate or prevent them. This
 "residual" risk approach provides environmental program managers with a view of their
 unfinished business and can help them set priorities for further risk reduction or preven-
 tion efforts. Environmental problems can pose risks to humans and ecosystems; they can
 also degrade the quality of life. Each type of risk is distinct and important. For example,
 non-point source  pollution  not only causes damage to ecosystems, it also causes large loss-
 es in recreational opportunities. Likewise, human or ecological risks from the accidental
 release of an oil tanker or a nuclear power plant can be calculated, but only a quality-of-
 life assessment can detect the impact oh a community's peace of mind. Thus, it is impor-
 tant to look at environmental problems from each of these perspectives: human health
 risks, ecological risks, and risks to the quality of life.
                                  •• •    ,..['     ' . • '        ,      ' .    .',
 Human Health Risks                 .
   These risks involve actual, estimated, or anticipated cases of human disease or injury
 caused by environmental problems. These include both carcinogenic effects, such as lung
 cancer from indoor radon, and non-cancer health effects, such as retarded mental develop-
 ment caused by ingesting lead in paint or soil.
                -              .    ,        j        '   •       ',!•''',
 Ecological Risks                       \
   These involve actual, estimated, or anticipated damages to the structure and function of
 natural ecosystems as well as to their biotic and abiotic components, Examples include:
 effects on animal and plant species due to eutrophication of water bodies caused by agri-
 cultural or urban runoff (i.e., non-point source pollution), fragmentation or loss of
 wildlife habitat, physical landscape modification and degradation, and reduced tree
 growth and increased susceptibility to pests in forests exposed to high levels of ozone.
 September 1993                ^                                             2.1-7

A Guidebook to Comparing Risks and Setting Environmental Priorities
Risks to the Quality of Life                 ,
   Environmental pollution can also cause negative economic and social impacts.
Quantifiable losses include increased maintenance costs of paint and other materials
exposed to acid deposition, reduced recreational use of water bodies polluted by industrial
discharges, the costs of replacing or treating contaminated water supplies, and the costs of
medical treatment and lost productivity for individuals suffering adverse health effects.
Non-quantifiable social losses include the sense of loss in community cohesion or cultural
continuity, the anxiety of living near an environmental threat, the issue of intergenera-
tional equity and leaving a degraded natural heritage to future generations, or the lost  .
enjoyment value of open spaces.              • •    '

   As a priority-setting tool, comparative risk is more relevant to long-term strategic plan-
ning and budgeting if it captures a sense of both current and future risks. For example, .a
few environmental problems, such as global warming and the irreversible loss of habitat   .
and biodiversity, may have potentially catastrophic consequences  if actions are not taken
in the short run to avert or minimize them. However, developing realistic and conservative
scenarios of future conditions that are consistent across the full spectrum of environmental
problems is fraught with difficulties and uncertainties. Fortunately, the differences in the
magnitudes of various environmental problems are great enough that it is possible to reach
consensus on a rough ranking of problems, despite these difficulties and uncertainties. For
instance, the ecological effects and risks to human health due to waste-water discharges are
relatively short term when compared to species extinction.
   A number of different approaches can be taken to assess trends in  risk. Trend analysis
can use sophisticated fate and transport, demographic, or  economic models, vast amounts
of data, and intensive data analysis to estimate future conditions affecting environmental
risks. However, trends can also be analyzed less quantitatively to determine whether a
problem is likely to get worse, stay about the same, or improve over time. The ranking of
problem areas can then be modified on the basis of informed judgments concerning risk
trends.          •                      .
   The evolution of comparative risk has been to move away from assessing only current
residual risks (i.e., a "snapshot" assessment) toward a more forward-looking analysis.
Taking the synoptic or "snapshot" approach is analytically easier—it does not involve
making future projections about contamination levels, exposures, or the effectiveness of
future control programs. However, it ignores one of the most important aspects of risk;
the changing magnitude of risk over time. Setting environmental priorities by focusing
exclusively on the current level of risk has proven to  be unsatisfactory in most cases.
   In practice, it is difficult to be completely consistent in applying the same time frame to
all problem-area assessments because of the different nature of environmental problems,
the uncertainty of future conditions, and the availability of data. Some problems are of
concern due to historical losses, such as wetlands or wildlife habitat losses, while other
2.1-8         ,                                                     September 1993

                                                               2.1 General Analytical luues
  problems may pose only minimal current risks,, but potentially catastrophic future risks.
  Therefore, some comparative risk projects have assessed current risks for many problem
 , areas and future risk trends for a few well-studied (and modeled) problem areas such as
  global warming and stratospheric ozone depletion.       .
    Analysts should be mindful of the time lags between the release of a contaminant into '
  the environment and the ensuing health or ecological effects. For instance, cancer cells can
  become malignant and metastasize years, or even decades, after exposure to the contami-
 ,nant. Conversely, some risk estimates may not reflect current risks as much as they reflect
  exposure to persistent contaminants that are no longer in use. For examplei some of the
  more publicized and currently perceived risks from pesticides (e.g., high levels of DDT in
  lake trout, chlordane in crabs, eggshell thinning among eagles) are due to the persistence  '
  and bioaccumulation of pesticides used decades ago.
    Discounting is a technique used in many financial calculations to account for the fact
  that the future value of a given amount of money is less than the same amount of money
  today due to inflation and the lost opportunity to invest the money. The same technique
  can be used to discount future health or ecological risks on the presumption that effects
  experienced in the future are less "important" than those same effects would be if experi-
  enced today. On balance, explicit use of discounting in comparative risk analysis raises dif-
  ficult ethical issues and adds little in the way of precision. However, it 5s recommended
  that comparative risk analysts note in some way the time frame during which risks occur
:  for all problem areas.                        ;
    Whatever approach is taken, project participants are encouraged to consider all options
  and to be explicit about the choices they make so that everyone operates under the same
 ground rules. Single-point  estimates of excess cancer cases or values calculated from a for-
  mula are simply not enough to characterize risks or rank problem areas. Decision makers
 also need to .understand the uncertainties and assumptions that underlie each risk assess-
 ment. Two of the most important pieces of information they need to know are when the
 risk is present and how long it will persist in th« environment.

    Defining the geographic scope of the project is one of the tasks that needs to be done
 before conducting the risk analysis. This involves deciding whether sources of pollution
 and their effects outside the area of the project should be considered and, if so, how they
 should be considered. Pollution from activities outside the project areaj such as acid depo-
 sition from a neighboring state or region,  can result in adverse health effects, environmen-
 tal damage, and/or a diminution in the quality of life. In addition to these "imported"
 risks, some risks generated within the project area may also be "exported" to other states or
 regions. An example of this is the interstate transfer and disposal of hazardous wastes. The
 most important thing is to  decide up front how these issues will be handled and to apply
 the approach consistently to the analysis of all problem areas.          ;
 September 1993                             '                                 2.1-9

A Guidebook to Comparing Risk arui Setting Environmental Priorities
Risks Imported From Other Areas
   Pollutants move easily across political boundaries. As a result, risks can be imported from
outside the project area or exported to other areas. The analytical issue is whether to analyze
and "count" these risks in the risk analysis and ranking process. For some problem areas, ,•
such as hazardous waste treatment and disposal, estimating imported risks may be relatively
straightforward because of tracking systems that are currently in place. However, for many
air and water pollution problems it may be impractical to separate contributions from out-
of-state sources. While the origin of the pollution may not affect the rankings of problem
areas, noting the percentage of in-state v. out-of-state pollution can be extremely important
information in deciding which risk management strategies to adopt and implement.

Risks Exported to Other Areas
   The majority of state and regional comparative risk projects to date have chosen not to
analyze and rank risks that are exported to other states and regions. While this may simpli-
fy the analytical requirements of the risk analysis, it may also result in missed opportuni-
ties to develop multistate or regional approaches to importantrenvironmental problems. In
contrast, the Vermont comparative risk project attempted to analyze the risks it "exports"
out of state (Vermont 1991). Even though they did not pose risks to the people and
ecosystems within Vermont, project participants were concerned about the effects of their
activities on other people and ecosystems outside of Vermont. A problem area called
"Vermont's contribution to ecosystem degradation outside Vermont" was divided into two
types of impact. The first type included risks that Vermont directly exports outside its
boundaries, such as hazardous waste transported and disposed of out of state. The second
type addressed risks stemming from goods and services Vermont consumes that are pro-
duced elsewhere. Because the consequences ofVermonters' consumpti9n of imported
goods and exported pollution are essentially unbounded, the problem area was not,
 ranked, but was discussed in the ensuing report as an "underlying issue," along with    ' ,
 unsustainable consumption and the  impacts of population growth. Just by considering,
 exported risks, Vermont's project participants hoped to make Vermonters more aware of
 their own contributions to national and global environmental problems.

 Transboundary Effects on Migratory Species
   Effects on migratory species present unique analytical problems in terms of how to
 characterize the size of the area affected. If a critical habitat of a migratory species is altered
 or eliminated, then a choice must be made about how to characterize the area pf impact.
 One choice would be to consider only the actual area of disturbed habitat. Alternatively,
 the area of impact could be considered to be the species' entire habitat. (The monarch
 butterfly's annual migration to Mexico exemplifies this issue: Its winter habitat encom-
• passes a small area in central Mexico. One approach would be to count only the area actu-
 ally disturbed. Alternatively, the  area of impact might be considered to be continental  in
 scope since this would encompass the monarch's entire range.) In Vermont, if the only
 2 i in                                                             September 1993

                                                               2.1 General Analytical louts
  nesting of a specie of migratory birds was eliminated, then it was considered to be a state-
  wide impact.             ,                                    .       •

    Once decisions have been reached on the. goals and ground rules for the project, then
  the first key analytical task is to establish a list of clearly defined environmental problem
  areas to be analyzed. This is a very important task because it affects how the analysis is
  conducted and may affect the risk-ranking results.
    There are a'number of alternative ways to generate a problem-area list. Given the differ-
  ent nature of environmental problems, there is no need for a single organizing approach.
  For instance, some problem areas, such as municipal waste water dischiirges to surface
 waters, are sources of pollution while other problem areas are specific chemicals or groups
 of chemicals, such as lead and asbestos or toxic air pollutants or pesticides. Still other
 problem areas are natural resources, such as ground water or wetlands; dial are affected by
 a variety of sources and activities. Each approach offers different strengths and weaknesses,
 and the various approaches are not mutually exclusive. The fact is that most projects to
 date have used some variation on the programmatic approach and have adopted pans of
 other approaches to the extent that the resulting problem-area list and definitions made
 sense for their projects. Thus, project participants are encouraged to explore all options
 while learning from others'experiences.   ..  '  i                     '
   There are numerous ways to create a problem-area approach, such as adopting existing
 lists from other state or regional comparative risk projects or soliciting citizens' views of an
 appropriate list. A reasonable approach might begin with brainstorming sessions among
 work group members, public interest and business groups, and scientists or academicians
 to generate many possible problem areas. In the initial phases, the process should be
 uncritical in that proposals are not subjected to rigorous scrutiny. This will encourage
 more creative thinking. It may also be advantageous to have more than one group generate
 a list of problem areas separately because different people wUl take different approaches
 and think in different ways about the task.      '
   Once a fairly comprehensive or exhaustive list: of problem areas has been generated,
 then  it can be evaluated in terms of a number of desirable characteristics by a selection
 committee. If more than one group has generated a list, then these lists should-be coa-
 lesced into a single list and evaluated. Potential criteria that can be used to evaluate a list
 of problem areas are described further on.            ,
   Using a group consensus process, problem ar
A Guidebook to Comparing Risks and Setting Environmental Priorities
   It may be useful to solicit public comment once a tentative problem-area list has been
agreed to by the committee. Comments can be solicited from other relevant state organi-
zations (e.g., departments of transportation, tourism, economic development, and hous-
ing), regional EPA offices, public interest and business groups, and the general public
through  polls, focus groups, or public meetings. The committee can then consider these
comments in its deliberations to finalize the problem-area list.

Desirable Characteristics                                .    '
   The following characteristics are-desirable in designing a problem-area list.
   •  Comprehensiveness. The list of problem areas should encompass all of the environ-
      mental threats within the project scope. The list should also account for the fact that
      pollutants move across media (e.g., air pollution is a major contributor to surface
      water pollution). However, there is a trade-off between the ease of analysis and
      attributing  all the cross-media damages to the relevant problem areas.
   •  Consistent Level of Aggregation. To make fair comparisons across problem areas, the
      areas should be defined at roughly similar levels of aggregation. For instance, if air
      problem areas are divided into several categories, then water problem areas should
      also be divided into a number of categories in order that ranking is not determined
      by the sheer size of a problem area.
'   •  Minimum Overlap. It is desirable to minimize overlap between problem areas and
      the resulting "double counting" of risks. Overlap will occur when problem areas are
       not defined along a consistent dimension (e.g., by source or effect). However, since
       it  is .not a realistic expectation to use a single dimension for developing a problem-
       area list, trade-offs must be made between minimizing overlap and generating a list
       that is comprehensive, understandable to the public, and can be implemented.
       Double counting is further discussed below.
    •   Ease of Analysis. Some consideration should be given to the way data are collected
       and stored when problem areas are defined so that unnecessary difficulties in .data
       analysis are avoided. For example, criteria air pollutants are often defined as a prob-
       lem area because federal and state agencies, as part of their specific regulatory
       responsibilities, have collected data on these chemicals and compounds as a group.
       To break this problem area up into smaller pans or to add other chemicals to it may
       be warranted for other reasons, but It is useful to consider the implications of data
    •  Ease of Implementation. The purpose of conducting a comparative risk project is not
       to produce reports, but to use the information and insights gained from the process
       to reduce or prevent risks in the most efficient, effective, and equitable ways. Thus,
       an important consideration in developing a problem-area list is the relationship
       between problem areas and organizational structures that  will implement risk man-
       agement strategies.
                                                                      September 1993
                                                                      •        •

                                                              2.1 General Analytical Issues
                                          I  '                   '    i
   •  Ease of Communication. To be catalyse for action, .problem areas need to be mean-
      ingful and understandable to the public. If problems that the public cares about are
      missing or are unintelligibly defined, then policymakers will have more difficulty
      communicating and implementing the results of the project.   '
   In general, it is preferable to define mutually exclusive problem areis in order to avoid
 "double counting" the same risksnn more than  one problem area. This type of overlap
 results in overstating the actual risks for those problem areas at the expense of other prob-
 lem areas. However, there are situations where double counting risks is not only unavoid-
 able, but can be very useful in terms of balancing this criterion with oilier desirable char-
 acteristics, such as creating a problem-area list that makes sense and that is understandable
 to policy makers and the public An example of this is provided by the dilemma posed by
 the ground-water problem area.
   Ground water can be contaminated by numerous sources, such as pesticides, leaking
 underground storage tanks, salt/sand mixtures used to de-ice slippery roads, solid and haz-
 ardous waste sites, improper storage of hazardous materials at all sorts of commercial and
 industrial facilities, and residential septic systems. Questions arise as to how to allocate
 these risks. At first glance, counting ground-water risks in the problem areas where they
 occur would seem to be the best approach. For example, ground-water contamination
 associated with hazardous waste sites would be counted as one of the risks for the haz-
 ardous waste problem-area. However,  it has been found from past comparative risk pro-
 jects that ground-water risks become "lost" among a number of different problem areas as
 a result. This has created difficulties in communicating a comprehensive picture of the
 risks posed by and to ground water.          I
   Due to the enormous public concern,with contaminated ground water, some projects
 have created a separate "aggregated" ground-water problem area that describes the risks
 associated with  ground-water contamination from all sources. However, the disadvantage
 of this approach is that by eliminating the grouind-water contamination component from
 other problem areas (e.g., hazardous waste sites), a significant component of those prob-
 lem areas is stripped away. The aggregated approach-is used to avoid double counting the
 risks, but it may be very confusing to the public and difficult to explain why contamina-
 tion of ground water caused by hazardous waste sites is not counted as part of the haz-
 ardous waste problem,                      i
   In response to the difficulties posed by the first two options, a third option has been
 developed that allows the risks of ground-water  contamination to be traced back to its
 sources and counted in a separate problem-area,  that pulls all the souros of ground-water
 contamination together into one problem-area. The disadvantage of this option is that
there is no attempt made to minimize the double counting of risks. In the relative-ranking
process, this will tend to overstate the risks associated with ground-water problem areas at
the expense of other problem areas.          |
September .1993                 .         ,                                 2.1-13

A Guulebock to Comparing Risks and Setting Environmental Priorities
   Thus, each of the three options above offers advantages and disadvantages. There are
no easy or "right" answers, but these types of decisions have important implications that
should be considered carefully by project managers working with their technical advisors.

Alternative Approaches for Defining Problem Areas
Along Programmatic Lines                        *
   Most state health or environmental protection organizations are structured along media
"program" lines (i.e., the air, water, waste, and toxics programs). In general, air programs
tend to divide problems by pollutant type — radon, criteria air pollutants, and toxic air  ;
pollutants. Water programs tend to divide problems by sources — industrial, municipal,
and non-point source discharges. Waste programs tend to differentiate between the types
of sites, while toxics programs analyze individual chemicals or groups of similar chemicals.
The differences are in large part due to the structure of individual statutes that authorize
these.programs. Table 2.1.1 illustrates the^reakdown. of problem areas using. the program-
                 "'"         ~V  -                                '-         -  - '
                                     Table 2.1.1:
                Sample Problem Areas Defined Along Programmatic Lines
(by source)
Municipal & industrial
waste-water discharges
Non-point discharges
(by pollutant)
Air toxics
Climate change
Stratospheric ozone
Indoor air pollution
(by site)
Abandoned hazardous
waste sites
Active hazardous
waste sites
Municipal solid waste
industrial solid waste

(by chemical)
Lead in all media
Asbestos ,

   Using a programmaticapproach offers some important advantages, such as making it
easier for program analysts to analyze environmental problems with which they are most
familiar. It also allows project managers to quickly and easily identify individuals and
offices with the requisite knowledge to analyze problem areas, and to hold them account-
able for making progress to reduce risks. EPA's Revised Core List of Problem-areas has been
included as Appendix A.          '                                       •
   However, as EPA's Science Advisory Board pointed out in its critique of EPA's
Unfinished Business report (1987), "the listed problem areas were not categorized in paral-
lel [and] are much more attuned to programmatic considerations within EPA than they
are to actual environmental problems in the real world.... Furthermore, the EPA list of
problem areas is inconsistent with respect to the level of resolution of the classification"
(EPA 1990b). For instance, active and abandoned hazardous waste sites are managed
under different programs (i.e., RCRA and Superfund). This legal distinction concerning
the status of ownership holds no special significance to the people or ecosystems at risk
from such sites. In addition,  the programmatic approach does not lend itself well to multi-
September 1993

                                                               2.1 General Analytical Issuts
  media (e.g., air and water) effects or risks to human health or the environment from a
  variety of environmental problems in a specific area.
  By Source Type
    Defining problem areas by their source offers several advantages, but it does not work
  equally well for all problem areas. For example, this approach simplifies the task of analyz-
  ing risks for environmental managers and analysts because many environmental problems
  can be traced back to their sources. It is used to define many air and water environmental
  problems whose sources are easily identifiable. Unique insights can be gained by analyzing
  problem areas by source. For instance, instead! of analyzing criteria air pollutants as a
  whole problem-area, one might analyze air pollution risks caused by mobile sources (e.g.,
  auto, truck, and train emissions) separately from risks caused by stationary sources (e.g.,
  power plants and factories). Table 2.1.2 provides an example of what a problem-area list
  would look like using this approach.        I

                                     Table 2.1.2:
                    Sample Problem Areas Defined by Source Type
Industrial & municipal
waste-water discharges
Agricultural practices
Urban runoff
Waste sites
Stationary sources
Mobile source!;
(autos and trucks)
waste products
Retail wastes
Industrial plants
                '                   •       I
   Some environmental problems, such as global warming or ground-water contamina-
 tion, are not easily defined in terms of their sources because they have a multitude of    >
 sources. It is easier and more logical to define them in other ways. For instance, indoor
 radon is a widespread and naturally occurring gas that can concentraw: in homes whose
 designs inadvertently trap these gases. The important fact about radon Is not its source but
 its presence in peoples' homes. Trying to define radon, or a number of other problems, in
 terms of their source can quickly become unwieldy and circuitous. However, as a general
 rule, tracing problems back to their sources is & helpful way to define problems.
 By Pollutants or Strescon                 |
   Many public health and environmental protection organizations have programs to
 respond to risks posed by individual chemicals or "families" of similar chemicals (e.g.,
 environmental lead and toxic air pollutants). Pollutants or stressors found in many com-
 parative risk problem-area lists include pesticides, asbestos, and physiail stressors to terres-
 trial  and aquatic ecosystems. However, like all the other approaches mentioned, defining
 problem areas by pollutant or stressor works better for some problems dian others. If an
 attempt is made to apply this approach to all problem areas, then it is quite possible that a
 number of problem areas will become "lost* or unrecognizable able to the public. For
 example, it is just more intuitive and easier to communicate a problem-area called ground-
water contamination than to identify the problem by die pollutants and stressors affecting
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorisus
ground water. Exhibit 2.1.1 provides a partial list of problem areas that could be devel-
oped using this approach.
            Exhibit 2.1.1:
   Sample Pollutants and Stressors
   • Hazardous organics & inorganics
   • Gaseous phytptoxicants
   • Ozone.-depleting gases
   • Chlorination products
   • Nutrients. BOD, turbidity
   • Microbes
   • Physical stressors
   • Thermal pollution
   > Acid deposition
   • Pesticides
   • Lead, PCBs, asbestos
                                          In the past, many organizations' activities
                                       have been focused on chemical stressors affect-
                                       ing human health, such as lead or radon. An
                                       emerging'area of concern involves the ecologi-
                                       cal impact of physical stressors upon the envi-
                                       ronment, such as fragmentation of critical
                                       habitats caused by urban sprawl and highway
                                       construction. Examples of physical stressors
                                       include river channelization and water with-
                                       drawals, resort or recreational developments,
                                       and mining, timber harvesting, and range
                                       management practices.
             Exhibit 2.1.2:
     Samples of Affected Resources
By Affected Resource
   The resource approach analyzes environmental risks in terms of the natural or cultural
resources affected by various environmental problems. Because this approach is organized
around resources, it has a geographic or spatial orientation that makes it particularly useful
for understanding the ecological effects of environmental risks. Like other approaches, the
resource approach is more suited to some environmental problems than it is to others.
   Natural resources are typically divided into a number of categories, such as surface
water, ground water, grasslands, forest types, critical wildlife habitats, and freshwater as
well as marine, wcdand, and estuarine ecosystems. Exhibit 2.1.2 provides a number of
natural resource categories that can be used in comparative risk projects.
                                         For instance, Colorado's comparative risk
                                       project included some unusual problem areas,
                                       such as open space, soil erosion, damages from
                                       changes in water quantity, and resources of spe-
                                       cial  interest. The state of Washington analyzed
                                       risks to agricultural and range lands as well as
                                       the risks caused by those activities. ,
                                         States planning to conduct a comparative
                                       risk project should consider using EPA's
                                       Environmental Monitoring and Assessment
                                       Program's  (EMAFs) landscape characterization
                                       scheme for terrestrial ecosystems. EMAP is
 expected to become the primary monitoring and assessment system on the status and
 trends of natural resources for EPA and other federal agencies/States may become partners
 in EMAP by contributing arid receiving information. Several states have  already made sig-
     • Rivers, lakes & streams
     • Oceans & coastal areas
     • Estuarine areas
     • Ground-water contamination
     • Outdoor air
     • Indoor air
     • Open spaces
     • Agricultural lands/topsoil loss
     • Special areas/habitats
     • Rare & endangered species
     • Urban areas/cities
                                                                    September 1993

                                                              2.1 General Analytical Issues
nificam commitments to EMAP, such as Pennsylvania and Illinois. Or.her states are con-
sidering how best to utilize this new program.;                     :"'
By Geographic Area                     .             '  •         F
   The geographic approach is very similar to the resource approach, but differs in that
specific areas are selected as problem areas instead of ecosystem types. It is away to match
geographic areas to the specific stressors affecting them and to analyze the risks in a more
focused way. The advantage of this approach is that it encourages'a multimedia, holistic
approach to environmental management in areas of special public concern and interest.
The disadvantage is the inevitable double counting entailed and the requirement for better
georeferenced data (i.e., data whose location can be pinpointed to a specific spot or area
on a map). Exhibit 2.1.3 lists sample geographic areas.
             Exhibit 2.1.3:
      Sample Geographic Areas
     • Water bodies
         (e.g., the Great Lakes)
     • Water basins
         (e.g., Chesapeake Bay)
     ,• Airsheds
     • Cites/urban areas
     • Rural or open .areas
     • Protected areas
         (e.g., parks and preserves)
                                           ;  For instance, instead of analyzing risks to
                                           a certain type of forest in (general, regardless
                                           of its location within the study area, specific
                                           forests of that .type would be analyzed sepa-
                                           rately. The reason is that different forests,
                                           even of the same specie;, can be exposed to
                                           very different stress regimes depending on
                                           their location. The Guam comparative risk
                                           project is facing this issue (CDS  1993).
                                           Project participants them have to decide
                                           whether to analyze two separate and quite
                                           different coral reefs on cither side of the
                                           island as a single problem-area (the
"resource" approach) or as two separate problem areas (the "geographic" approach)
because of the different stress regimes and risk management options that they pose to deci-
sion makers.    .                         .   i   .    •

   Specific geographic areas can be selected as problem areas on the basis of a number of
factors, such as scarcity, vulnerability to stress, recovery potential and time, or because they
are highly valued by the public. Usually, they are natural resources or aireas of special inter-
est and value. Entire water basins or specific wetlands, estuaries, lakes and bays, rivers and
streams, or stretches of coastline can be selected as problem areas. Specific airsheds can
also be identified so that risk managers can not: only rank air problems but also target
response actions geographically. Waste problem areas can be considered a single hazardous
waste site if it is deemed important and visible enough that decision makers anticipate the
public will ask what the specific associated risks are.
By Economic Sector                                            '          •
   The sector approach analyzes risks to human health, the environment, and the social
and economic quality of-life caused by activities in different sectors of the economy. Thus,
examples of problem areas using this approach would include those listed in Exhibit 2.1.4
This approach can be used in combination with other approaches by shuffling around dif-
ferent components of problem areas into economic configurations. By looking at risks
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
from various angles, decision makers can gain new insights into the real "drivers" of envi-
ronmental risk and develop more creative and innovative risk reduction strategies.

             Exhibit 2.1.4:                  For instance, it is possible to combine the
       Sample Economic Sectors	•   ecological impacts of a number of problem
                                         areas (such as non-point source pollution of
      > Transportation
      > Light manufacturing
      • Heavy manufacturing
      • Commercial development
      1 Residential development
      1 Energy production
       Waste-disposal industry
       Resort industry/tourism
       Road construction
      • Silviculture
      • Agriculture
      1 Military
surface waters, pesticides, soil erosion and
sedimentation, and the physical alteration of
terrestrial habitats) into a single economic
sector (i.e., agriculture). By combining the
risks associated with these problems and
attributing them to a single economic sector,
it is possible to gain an enhanced view of .the
full impact of agriculture on ecosystems. This
approach can also be applied to human
health risks from agriculture by looking at
       Non-military government         ...   •...           - • j    -j      c  j
                                   -      such issues as pesticide residues on rood, pes-
                                         ticides in drinking water, and risks to farm
workers. The main drawbacks of this approach are the overlap and potential double
counting of risks among different sectors of die economy, and die somewhat artificial
assignment of risks to, a particular sector when it may actually involve several sectors
Combining Different Approaches
   The way that problem areas are defined has substantial influence on the nature of the
solutions that are considered. Thus, it can be useful to use multiple approaches to prob-
lem-area definitions to generate a rich variety of potential solutions to environmental
risks. After analyzing problem areas defined along programmatic lines, for instance, it is
possible to reconfigure problem areas differently to answer questions, such as: Which par-
ticular pollutants seem to have produced die bulk of the risks for the higher-risk prob-
lems? Which particular sources are responsible for die bulk of die risks? Are large amounts
of these pollutants or source types associated widi particular economic sectors? Is there any
information to indicate that risks are high in one particular geographic area? Table 2.1.3
from the Vermont comparative risk project demonstrates diis relationship between die
source and fate of stressors (Vermont 1991).
   By defining or reconfiguring problem areas differently, it is often possible to understand
the underlying causes or activities that create significant risks to human health, the envi-
ronment,  and to society's quality of life. Economic sectors, pollutants, or geographic areas
can be used as organizational aids. For instance, from a management perspective, it may
be very useful to understand the total impact from any of these perspectives. In addition,
dicre is no reason why more than one dimension cannot be used in this type of analysis
simultaneously, so that new insights about economic sectors, pollutants, and/or geograph-
ic areas are gained leading to more integrated risk management strategies.
2.1-18                                                             September 1993

                                                                 2.1 General Analytical Issues
      Energy production/consumption
                                       Table 2.1 J:
                    Relationship Between the Source and Fate of Stressors
       Domestic and industrial waatewater treatment/disposal
      Farming/forestry practices
      Hazardous waste disposal
      Solid waste disposal: landfill
      Solid waste disposal: incineration
      Domestic and commercial me of toxic materials
      Construction and development activities
      Stressors end up in:
      Ambient air
      Indoor air
      Drinking water
      Surface water
      Ground water
     Source: Envinnmtig 1991: Siitt to Vermont and Vcrmoiutrs.
   One of the gods of a comparative risk project is to rank problem areas into different
 categories of risk. The process of ranking problems is difficult, however. Deciding which
 problems are most serious requires dozens of judgments about controversial facts, uncer-
 tainties, and values. Before ranking risks, it is important that all project participants, espe-
 cially those actually performing the ranking, understand the importance of establishing
 criteria to rank problem areas, the summary nature of the rankings, and the difference
 between the risk rankings and management priorities. This section discusses issues
 involved in the process of ranking risks, presenting and evaluating different methods of
 ranking risks, and describing various presentation tools,

 The Importance of Criteria
   One way to make this difficult process more manageable is to discuss and agree upon a
set of criteria for ranking problems. Criteria define what is important in thinking about a
particular kind of risk. They also allow participants to make a series of incremental judg-
ments, carefully piecing together an overall picture of risks, instead oif making sweeping,
September 1993

A Guidebook to ComparingRuks and Setting Environmental Priorities
complex judgments. Explicitly defined analytical criteria force participants to systematical-
ly think about their decisions and the underlying rationale. Arid only by being explicit
abouc these incremental judgments can projects persuade other interested or affected par-
ties that the process and its conclusions make sense and deserve attention. Regardless of
whfch ranking methods and processes participants choose, or which criteria they select,
the ranking process should be structured around a set of agreed-upon criteria.
  The following example illustrates the importance of criteria. Two participants charged
with ranking risks to human health may rank the risks from abandoned hazardous waste
sites and criteria air pollutants very differently. Even though .they may use the same facts to
make judgments, their rankings of these, two problems may be different because they used
different criteria. One person may have focused on the total number of cases, and ranked
abandoned hazardous waste-sites low and criteria air pollutants high. If the second person
was more concerned about the equity of risks—that no person should be exposed to signify
candy higher risks than anyone else—then they might have ranked hazardous waste risks
higher than criteria air pollutants since the risks of hazardous waste sites are borne almost
entirely by a small group of individuals living near the sites. Different criteria produce dif-
ferent rankings, so identifying them is critical to a successful ranking process.

Rankings as Analytical Summaries
   In an ideal comparative risk project, the final risk rankings should be the most scruti-
nized and used but least important component. This is because the rankings are simply
summaries of the analysis. If data are carefully collected and analyzed, analytical criteria
articulated, uncertainties identified, and participants' values specified, then the ranking
results should be fairly evident. Decision makers can use the rankings without reviewing
all  the information and judgments made by the ranking group. This also allows project
participants to effectively explain and defend the results because the rankings accurately
reflect the analyses and judgments they have made throughout the project.
   The ranking process poses the ranking committee with a dilemma—how precisely can
and should they rank the problem areas? The more distinctions they can identify, the
more useful the rankings will be to decision makers and the public. All comparative risk
projects to date have ranked problem areas into at least three groups, ranging from higher
to  lower risks. Most projects have used four or five groupings. Several projects have resist-
ed labeling problems as "low" risks, since participants were concerned that readers would
 misconstrue the results as indicating that "low" problems are unimportant. In actuality,
these problems are only "low" relative to the other problems analyzed by the project,
 rather than in any absolute sense.                             '

  What the Rankings Mean—Risks v. Priorities
    Interpreting the rankings is typically one of the biggest sources of confusion during and
 after most comparative risk projects. What does it mean if a problem is ranked "high"?
Will the organization devote more resources to it? Does it mean the problem is paiticular-
 2 j_20                                                             September 1993

                                                               2.1 General Analytical laues
 ly difficult or easy to solve? Can an organization focus ori lower-ranked problems, of
 should it reduce resources to those areas?       :                 •
   ••'•-•,                               ] .  '•                  \
   Such questions hinge on whether the rankings only reflect environmental risks or
 whether they are intended to convey management priorities. There is a reason why an
 organization's priorities may not correspond dinxtiy to the ranking results. Priorities must
 be set within the institutional, social, political, technological, and economic realities that
 can place real constraints on proposed risk management strategies. For example, a state
 public health or environmental protection organization may lack the legislative authority
 to address a certain environmental threat, there may not be any cost-effective technologies
 available, or there may be insufficient numbers of trained personnel to reduce the risk.
 These considerations as well as other risk management issues are discussed in  Section 3.1.

 Ranking Methods                         1
   There are three basic kinds of ranking methods: negotiated consensus, voting, and for-
 mulas. These methods form a progression from relatively unstructured -to very systematic,
 structured approaches.,                        !                     j
   •   Consistency. The method provides a consistent basis for comparing; and ranking
      problem areas. .For example, the use of secret ballots can  lead to inconsistent results
      if participants ignore the evaluative criteria! or apply them differently to  different
      problem areas.                    '      ! '         .  .      '             •
   •   Fairness. An open, inclusive process is encouraged and provides impartial redress
      procedures if bias is detected by anyone participating in the project.
   •   Documentation. This is important for the credibility of the project and ranking
      results. Participants must agree on, a single explanation of what occurred in the rank-
      ing process (including recognition of disagreements and debates) so that others can
      better understand or reconstruct-the process.             .       j
 Negotiated Consensus
   The objective of this approach is to reach agreement. Open discussion is often used,
allowing the group to analyze and argue about data, values, and uncertainties  in whatever
way seems most natural. Some problems will receive intense scrutiny and debate, while
others may be subjected to only cursory review. Although  negotiated consensus is the least
structured ranking method, most iterations roughly conform to the following steps:
   •   Review data. Participants present and discuss analyses of individual, problems,
      answering questions about the risk estimates, analytic methods, and assumptions.
   •   Take proposals for how individual problems should be ranked. Participants then propose
      that problems be placed into a particular category of risk. Unless there is an objec-
      tion or alternative, the ranking is not changed.
   •   Briefly discuss objections or alternatives to proposals. If the issue cannot be quickly
      resolved, then additional discussion is reserved for a later time. The group settles on
September 1993

 A Guidebook to Comparing Risks ami Setting Environmental Priorities
      those problems over which there is general consensus on their placement in one of
      the risk categories.                                                         •
   •  Discuss and debate unresolved objections, and rank remaining problems. The bulk of
      discussion is then focused on the remaining unresolved problems. In each case, dis-
      cussion hinges on disagreements-^clarifying positions, explaining criteria, and tak-
      ing informal polls to monitor progress. Debate continues until consensus is reached.
   •  Review results, employ other methods if necessary. If consensus cannot be reached, then
      another method can be used to produce a ranking.
   Some of the strengths of negotiated consensus are that the process is very simple, accu-
 rate, precise, explicit, and fair as long as discussion is vigorous and thorough. It also pro-
 vides a healthy environment for the mutual education of participants since all participants
 can contribute equally  Once consensus is  reached, group commitment to the results can
 be very strong.
   One of the weaknesses of negotiated consensus is that it is occasionally difficult to keep
 participants focused on the agrced-upon criteria. Documentation can be difficult because
 discussion is typically fluid and wide-ranging (recorders can be very helpful in this regard).
 If the discussion is not vigorous and thorough, then the process may be inaccurate,  impre-
 cise, or unfair. This can be particularly true if there are very dominant or reserved person-
, alities in the group; if the group is not diverse in skills, experiences, and beliefs; or if facili-
 tators are not available to manage the discussion.
 Voting                            "                ,
   Voting is the most familiar and frequently used method of ranking problems.
 Recognizing that there will often be unresolvable disagreements, projects may resort to
 voting as away to determine the  majority's will. There are at least three different voting
 methods, some of which may be  unfamiliar to participants. These include secret ballots,
 open voting, and multivoting.
   In secret balloting each individual has a single, secret vote to indicate how each problem
 should be ranked. Vote totals are then tabulated. Problems typically are ranked according
 to pluralities if no outright majority exists. If a problem receives seven "high" votes, four
 "medium" votes, and nine "low"  votes, the problem would be ranked "low," even though a
 majority thought it should be ranked higher. An alternative approach that  is more sensi-
 tive to differences of opinion would be to assign a value to each category (e.g., high * 3,
 medium = 2, low -  1). The arithmetic mean or average of the scores would then be used
 to determine where "natural" breaks in the distribution of scores occur so that problem
 areas could be placed into different categories of risk.
    Of en voting requires each person to identify his or her vote. Each person is given only
 one vote. Tabulation can be somewhat difficult with open voting, since participants may
 change their votes based upon what they observe from others. There are various ways to
 avoid vote-changing, such as having everyone vote simultaneously, or initially casting their
 votes in secret, revealing how individuals voted after the ballots are collected. Similar tabu-
 lation methods as described above for secret balloting can  be used.

 2 1.22                                                              September 1993

                                                               2.1 GeneralAnalytical'Issues
    In mukivotingali participant have the same number of votes. Participants can allocate
 their votes any way they prefer among the problem areas, although an upper limit can be
 set on how many votes can be assigned to a single problem. This method allows partici-
 pants to express the intensity of their opinions. For example, if each participant is given 10
 votes to divide among 20 problems, the group may decide to allow a participant to cast no
 more than 5 votes for any single problem. This prevents any one participant from having
 too much influence over the ranking of problem areas. Problem-areas are then ranked on
 the basis of votes received. Participants then usually use consensus, secret ballots, or open
 voting to decide where the breaks fall between the high-, medium-, and low-risk categories.
   In general, voting is simple and fair in that all problems are voted upon, all participants
 vote, and each participant has the same number of votes. Because it is so easy to produce a
 ranking with voting, there may be a temptation to cut discussion off cob early. This can
 cause the group to ignore complexity, magnify biases, and/or overlook data. Regardless of
 which voting method is chosen, methods are typically repeated several times during the
 project, or are used in combination. This gives participants a chance ico-explain their rea-
 soning and persuade others to change .their votes. In secret voting, participants are often
 asked to write down their reasons along with their votes in order to facilitate discussion
 and ensure that the agreed-upon criteria are being used to evaluate problem areas. -In open
 and multivoting, participants who voted in opposite ways typically present their reasons.
 Revealing the sources of disagreement can often lead to agreement once the reasons for
 disagreement are clarified. However, some disagreements reflect differences in values or
 priorities among participants and may not be resolved.  Multiple voting iterations can have
 the additional benefit of improving explicitness and recprd-keeping. When voting results
 cease to change with each iteration and participants have a clear sense of why the rankings,
 came out as they did, the rankings are complete.
       4                           '  '  "   \  ~      '      ,'•''•'''         ^ • •
 Formulas                                I                           ,
   Formulas share certain characteristics. Each: attempts to manage the complexity of
 analysis by breaking environmental problems into parts. Each of these parts is then evalu-
 ated and mathematically recbmbined to produce an output. Formulas can be applied to
 the entire ranking process, or used only in particularly complex or difficult portions.
Although it may not be apparent, it is importsint to recognize that value judgmehts play as
large a role in formulaic approaches as they do in other less quantitative methods, since
value judgments are needed to determine what criteria are useful, how they should be
weighted, and how they are combined arithmetically.
   For example, a workgroup composed primarily of health professionals could use nego-
tiated consensus or voting to rank health problems and  a formulaic approach to rank eco-
logical  and quality-of-life risks. Similarly, a group could use a formula to combine cancer
and non-cancer human health risks for each individual problem and then vote to rank the
problems  in relation to each other.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
   There are a wide variety of formulaic approaches to ranking, but only one has been
used in a comparative risk project to date. This approach is best described as "weighted
scoring" and involves five steps:
   1.  Identify criteria for evaluating risks.
   2.  Score each problem for each criterion.
   3.  Assign weights to each criterion.
   4.  Multiply the criteria scores by the weights and sum the results to produce a total
   5.  Rank problems according to total scores.
   In general, formulas have the following strengths and weaknesses: If properly construct-
 ed, they can provide the most accurate and precise rankings of any method. They are also
 very explicit about the relationships of different criteria, and are inherently fair, since the
 same criteria and equations are applied to. Formulas can also provide a clear record of how.
 the rankings were generated. Poorly constructed formulas, however can produce inaccu-
 rate results. Generally, this is not because of mathematical errors, but because participants
 do not folly understand the consequences of their choice of weights arid/or equations.
 Another weakness of formulaic approaches is the false impression of precision and level of
 understanding about risks to human health and the environment. In addition, while for-
 mulas can be very explicit about how ranking results were reached, they provide no insight
 into why the group chose certain criteria or assigned certain values to factors. Complex
 formulaic approaches may also be unfair to participants who do not have quantitative
 skills. Converting judgments and data to numeric scores requires that formulas be hypoth-
" esis-tcsted to ensure that they behave as  intended. Careful thought needs to be given to
 the appropriate mathematical operations (i.e., summing, multiplying, or dividing) within
 a formula. Finally, complex formulas can be difficult for readers and users of the rankings
 to understand.                                                  ;
    One formula developed by EPA's Region VI comparative risk project, the Ecological
 Risk Index Formula (ERIF), provides an excellent example of how a formulaic approach
 was used to rank the ecological risks of environmental problems in that pan of the coun-
 try. The ecological work group selected  the following criteria as the most important factors
 in determining ecological risk, and used them to develop the ERIF: Area of Impact/Area
 of Ecoregion, Degree of Impact, and Degree of VulnerabUity. Exhibit 2.1.5. depicts the
 formula that was developed'by the work group. This relationship can be described in
 words as "the percentage of each ecoregion affected by a strcssor multiplied by the severity
 of the stress multiplied by the vulnerability of the ecoregion."
    Taking just one of the criterion for ease of explanation, "Degree of Impact" was calcu-
 lated by analyzing the effects of different stressors on a number of important ecological
 functions such as the capacity of ecoregions to filter and detoxify pollutants. The next task
 the work group faced was to figure out  how to objectively measure the degree of impact
 for each eqological function. Descriptions of various levels of impact were written for  each

 2 .  24                -                                             September  1993

                                                               2.1 General Analytical Issues
 function and assigned a numerical value. The resulting scale of impact, illustrated in   ••',.
 Exhibit 2.1.6., describes different levels of impact on an ecoregion's ability to filter and
 detoxify pollutants from air, water, or soil.
   Determining whether-an environmental problem causes a Level 2 or Level 3 impact
 requires a great deal of professional judgment. There are no "hard" or entirely objective.
ways to make this, or many other, decisions without some level of subjectivity. In fact,
 attempts to remove professional judgment and experience from the process can prove
 counterproductive, as data and analytical tools sire almost always inadequate to fully
 describe the nature and  magnitude of risk. However, professional judgment can be incor-
 porated into the process in a consistent and structured manner to minimize bias.

         Exhibit 2.1.5: EPA Region VI Ecological Risk Index Formula          .
                    Summation over degrees of vulnerability
                       Summation over degrees of impact
  ERI =
-• ^
Ii * D Vj
                                                         Key Criteria
                    ERI-Ecological Risk Index      j DI-Degree of Impact
                      n- Number of Degrees of Impact DV^-Degree of Vulnerability  ;
                    AIj - Area of Impact          !  y)' Number of Degrees of Vulnerability
                    AE- Area of Ecoregion          '                 ,
   The numerical values assigned for each score on every factor were then summed togeth-
er to produce a "Degree of Impact" score for each ecoregion. These scores were then com-
bined with the scores of the other two criteria (i.e., "Degree of Vulnerability" and "Area of
Impact") to generate a total "Ecological Risk Index" (ERI) score for that problem-area for
that particular ecoregion. The scores that were generated for all problem areas in all ecore-
gions then served as the basis for ranking the risks of problem areas and ecoregions; the
scores did not completely determine the rankings. The work groups used the scores as a
starting point for additional discussion and a more focused review of key data. Final rank-
ings were determined on the basis of a consensus-building process, subjxt to the rule that
any changes to the ERI rankings had to be explicitly justified in terms of disagreements
over the scores assigned to factors.             !
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
Other Approaches
   Among many other possible approaches to ranking risks, three that have not yet been
applied to a comparative risk project hold promise: decision trees, decision analysis, and

analytic hierarchy process.

   Using decision trees as a variant ofthe weighted scoring method offers a more detailed
way to reflect uncertainties. Whenever there is significant uncertainty about what score a
criterion should receive, participants can lay out two or more possible scores and then
assign a probability to each. In the Region VI example, each criterion was estimated with a
single number. In some cases, these estimates may have been very uncertain. For example,
the group could have identified a range of possible scores and their probabilities to reflect
the uncertainty imbedded in their'estimate of an ecoregion's diminished ability to detoxify
and filter contaminants. Assuming that the group believed that the degree of impact
ranged from a Level 2 to a Level 4 impact, and could agree to assigning probabilities to
the different levels of impact, a decision tree reflecting the ecoregion's capability to  filter
and detoxify pollutants might look like Exhibit 2.1.7.

                                   Exhibit 2.1.6:
                   Filtering/Detoxifying Scale for Degree of Impact
       Level 1: Problem reduces assimilative capacity of the natural system through
               destruction of vegetation and microorganism populations.

       Level 2: Problem exceeds the assimilative capacity of the natural system for
               less than a year.

       Level 3: Problem exceeds the assimilative capacity of the natural system for
               more than 1 year and less than 5 years.

       Level 4: Problem continually exceeds'the assimilative capacity of the natural
               system. Problem lasts more than 5 years but less than 50 years.

       Level 5: Problem continually exceeds the assimilative capacity of the natural
               system for more than 50 years.                        ." .	

                                  Exhibit 2.1.7:
             Probabilities of Different Degree-of-Impact Estimates
    Effect on an
    Detoxifying and
    Filtering Abilities
                                        Level 2 Impact = 2
Level 3 Impact = 3
Level 4 Impact = 4
                                                                  25% chance
                       -  50% chance
                 Sum of Factor C = 2(.25) + 3(.50) + 4(.25) = 3
                                                                  25% chance
                            September 1993

                                                              2.1 Genera} Analytical Issues
   Participants can then calculate a score and probability for each of these options. If the
score changes significantly based upon these calculations, then the group will have identi-
fied a key variable that may merit additional research and discussion. By taking advantage
of this approach's strength in bounding the uncertainty of estimates ajid forcing partici-
pants to consider the plausibility of various scenarios seriously, it leads to better-informed
rankings. However, constructing a full-size troe (including all major criteria and uncertain-
ties)  can be exhausting and not always productive. In the Region VI equation, there are
78,125 possible combinations for the seven factors (each having a sole from one to five)
for the "Degree of Vulnerability" criteria alone. However, the sum of these seven factors
can only differ by 28, ranging from 7 to 35. Laying out the tree to discover which of the
78,125 combinations best fit the data could easily overwhelm the work group without
affecting the ranking at all. This is an important reason why no project to date has used
decision trees extensively. Decision trees would be most valuable where there are major
uncertainties and where the interactions of uncertainties are too complicated for individu-
als to keep track of mentally.               ;
   Decision analysis incorporates many aspects of decision trees, but is more sophisticated.
Decision analysis involves a complex, set of rules and axioms for structuring problems,
constructing elaborate decision trees, and modeling the values of participants. In addition
to ranking problems, decision analysis focuses on identifying solutions to problems. A full
description of decision analysis is beyond the scope of this document, but diere are many
source materials  and practitioners at  EPA, in academia, and among consulting firms.
   Analytic hierarchy process (AHP) takes a different approach to ranking problems. In
AHP, participants make many paired comparisons of problems. The basic principle
behind AHP is that while ranking 20 problems may be complex,  ranking 2 problems is
much easier. If a group does enough  paired comparisons, or "mini-rankings," in the right
combinations, then a ranking of all 20 problems can be generated from them.
   AHP also has the benefit of identifying inconsistencies in judgments. For instance, an
individual might decide that air toxics pose higher health risks than solid waste, and that,
solid waste poses higher health risks than ground-water pollution, but that ground-water
pollution poses higher health risks than air toxics. Inconsistencies like this (though usually
less extreme) often occur when individuals are asked to process complex information;
AHP highlights these inconsistencies and provides a more consistent approach to ranking.
For this reason, AHP should not be attempted without guidance from an expert trained in
its use. AHP has never been used in a state comparative risk project, but it has been used
as a priority-setting tool for underground storage tank (UST) programs in several states
and to rank Department of Energy defense production facilities.

 Criteria for Choosing a Ranking Method
   Each ranking method has different strengths and weaknesses. Evaluating a method in
accordance with the following criteria can help identify the one that best meets the objec-
tives of the project, and the needs and concerns of affected or, interested groups. These cri-
teria are:
 September 1993                          !.   .                               2.1-27

A Guidebook to Comparing Risks and Setting Environmental Priorities
   •  Accuracy. The relative ranking of. the problem-area reflects, the actual severity of the
     problem in the real world. For example, rankings can be inaccurate because of biases,
     uncertainties, and/or poor analysis or research.
   •  Precision. Problem-areas are ranked into as many categories as the data will support.
     Some methods can permit participants to make more distinctions than the data can
     support, resulting in false precision.
   •  Explicitnes!. The data, criteria, values, and uncertainties that go into the rankings are
     identified, along with the role each plays in the ranking process.
   •  Simplicity. Participants understand the ranking method and can communicate it to -
     the public without undue difficulty.
   All of the methods discussed above have been presented as if they were used individual-
ly to highlight their different characteristics. However,  methods are not mutually exclusive
and rankings are often arrived at by combining approaches. Using each method at different
stages in a ranking process draws upon the strengths of each, while minimizing its weak-
nesses-Participants should feel free to create their own methods. Creating .a unique rank-
ing method can generate enthusiasm among participants and allow the group to tailor the
ranking method to its own circumstances and needs. In creating a new method or mixing
different methods, participants should keep in mind how the choice of method can influ-
ence the rankings.

Presentation Aids
   The way information is presented to decision makers can profoundly influence how
well it is understood and how it is ultimately used. Spreadsheets and specialized software
 programs are invaluable in building, running, and maintaining many large data bases and
 complex models. Using computers to do complex and large numbers of calculations allows
 participants to quickly and easily do analyses that would otherwise take many hours. For
 example,'sensitivity analysis and "what-iP analysis can be especially important in distin-
 guishing important factors from peripheral ones.
   Matrices can be used with any method. A matrix simply presents two or more criteria
 on two axes. Its chief benefits are that it focuses participants' attention on the trade-offs
 between two variables at a time, is simple to construct, and  provides an understandable
 visual record. Exhibit 2.1.8. illustrates a hypothetical ecological matrix.
   If there are serious disagreements within the group, problems can be placed in more
 than one cell. This records disagreements that may require further discussion. In Exhibit
 2.1.8., if only these two variables (i.e., reversibility/recovery time and area of impact) are
 used as criteria to rank the four problems listed, then habitat .alteration would clearly be
 ranked highest. What about solid waste and air toxics problem areas? Ranking these prob-
 lems would require a discussion about the relative importance of "reversibility"  and "area
 of impact." Constructing a matrix can help promote discussion by clarifying the differ-
 ences between problem areas "and the relative importance of different criteria.
  2 j_
                                                                     September 1993

                                                             2.1- General Analytical Issues
Individual or Combined Ranking
                      • '*..,.          i'      ~ •
   Almost all comparative risk projects to date have generated separate rankings for
human health, ecological, and quality-of-life risks. Although ranking risks separately is
laden with value judgments, combining rankings into a single ranking poses especially dif-
ficult challenges. Technical expertise and information are essential in analyzing whether
one environmental problem causes more excess cancer cases per year than another prob-
lem. Technical information becomes less critical relative to the value judgments that must
be made when combining cancer and nonLcancer effects to rank human health risks. The
values of the ranking committee's members are far more important than technical deter-
minations made on the basis of supportable data when trying to create a combined human
health, ecological, and quality-of-life ranking.  ;            ,                      .
                                   Exhibit  2.1.8:
                       Example of a Two-Criteria Ecological Matrix
Recovery time

solid waste
Local i

_ \
Area of Impact
• ! ' ; '
air toxics
   If a group decides to combine rankings, then there are four basic methods: weighted
scoring, negotiated consensus, voting, and rules. Combining rankings with weighted scor-
ing, negotiated consensus, or voting works exactly as described earlier in this section,
except that discussion and debate play an even larger role. The most critical information
to combine rankings resides in participants' minds, not in any data bases or studies,
because value judgments become even more important.
   Combining rankings with rules involves eststblishing minimum requirements for a
problem to be ranked in a certain way. A hypothetical rule might be: Any problem diat is
ranked "high" for two of the three individual rankings will be ranked "high" for the com-
bined ranking. Another, more complex rule might be: A problem that is ranked "high" for
any individual ranking will be ranked "high" for the combined ranking, if it is not ranked
"low" for either of the other two individual rankings. Using rules to combine rankings
usually has two  consequences. First, the "high"  group of problems ends up being larger
than the "low" group, because groups often resist constructing rules that move problems
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
down from their highest individual ranking. Second, the rules seldom dictate where every
problem should fall. The ranking group must then use another method to complete the
combined ranking.                                 c
   Whether a ranking group should attempt to combine rankings depends on the man-
date of the group. Senior managers may give the group clear authority to combine rank-
ings. In these cases, the ranking group typically serves as a link to the public and the tech-
nical/scientific community. Senior managers may envision the project as providing guid-
ance for some of the most difficult decisions and may want that guidance to be as compre-
hensive as possible. Another impetus for combining rankings involves how resources are
allocated. Since an agency's overall funding is typically considered to come out of one
"pot," this creates a desire to establish a single set of priorities to guide the allocation of
those resources. The ranking team may be considered a good choice for the task, since it
has grappled with these issues. However, this view or impression is often incorrect. Due to
compartmentalized legislative authorities that tie the achievement of specific activity tar-
gets to funding, resources arc often unavailable for other purposes. Thus, resources are not
as "liquid" as they may seem because of the need for accountability to the
authorizing/appropriating legal bodies.                                          •
   In other projects, senior managers may envision the project as providing essential tech-
nical information in a useful form as an aid to setting priorities. In this view of compara-
tive risk, the usefulness of providing technical information becomes less important as
senior managers reserve the most important value judgments for themselves. Since com-
bining rankings does not provide additional technical information to senior managers
under this approach, and may distract the ranking group from its role as an evaluator of
technical information, the group's mandate may be more limited. Therefore, it is very
important that project participants receive clear guidance on how managers plan to use
the project results since this decision will heavily influence how the ranking group views
its proper role.
 2.1.30                                                             September 1993

                                                             2.1 General Analytical Issues

  Center for Development Studies (CDS), University of Hawaii and Pacific Basin
  Development Council. Comparative Risk Analysis for Guam Environmental'Protection
  Agency: Final Report.  Honolulu, Hawaii. January 1993.

  Colorado. Department of Health and Department of Natural Resources. Environmental
  Status Report: A Summary of the Technical Analysis of the Colorado Environment2000
  Project.June 1990.                        I

  U.S. Environmental Protection Agency (U.S. EPA).  Region VI Headquarters.
  Comparative Risk Project, Appendix A: Ecological Report. Dallas, TX November 1990a.

  U.S. EPA. Science Advisory Board. Reducing Risk: Setting Priorities and Strategies for
  Environment^ Protection. Report by the Ecology and Welfare Subcommittee. September
  l-990b.                                   !
    '              '           '             \'  f            '     '•-'.••'
  U.S. EPA; Office of Policy, Planning and Evaluation. Office of Policy Analysis.
  Unfinished Business:  A Comparative Assessment of Environmental Problems, Appendix II.  '
 Washington, D.C. February 1987.       .

 Vermont. Agency of Natural R&ouTc&.Envtrmment 1991: I&k to Vermont and
  Vermonters. Report by the Public Advisory Committee, The Strategy for Vermont's Third
 Century.  Waterbury, VT. July 1991.         ;

 Washington. Department of Ecology. The State of the Environment Report.  Environment
 20/0. Olympia,WA. November 1989.       1
September 1993                            ,                     '•         2.1-31


                          HUMAN HEALTH
Applying Risk Assessment Concepts to Comparative Risk Analyses	 3
S(ep 1: Identify Hazards —	
     Target Pollutants — —
     Relevant Exposure'Pathways
     Adverse Health Effects	
Step 2: Assess Dose-Response Relationship.
     Dose-Response Functions for Carcinogens

       Determination of Cancer Potency Factors..... ........... ^ ..... ', ...... . ...... .......... 8
       Availability of Cancer Potency Factors
     Dose-Response Functions for Non-carcinogens
       Determination of the Reference Dose........
       Availability of Other Maximum Safe Levels
Step 3: Assess Exposure	—:	
     Exposure Pathways	
     Sources and Releases of Pollution
     Fate and Transport of Pollution .
     Human Contact .'.	

 September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
Step 4: Characterize Risks	15
     Characterizing Cancer Risks	,	15
        Risk of Cancer to Individuals	-15
        Risk of Cancer to Populations...	.".	•	16
        Uncertainty	-	•	•	1°
        Presenting Cancer Risk Information, to Decision Makers   ,	....i.	17
     Characterizing Non-cancer Risks	....18
        Severity of Health Effects	I..	-	19
        Ratio of Dose to RfD	•	••••	•	21
        Evaluating Exposed Populations	••	22
        Presenting Non-cancer Risk Information to Decision Makers......	23
                                                             '                  '
Step 5: Rank Cancer and Non-cancer Risks	••••	....24
     Cancer Risk Ranking 	•	25
        Quantitative Factors	•—.	25
        Non-quantitative Factors	;	:••••	25
        Combining Quantitative and Non-quantitative Factors	......26
     Non-cancer Risk Ranking	•	.........27
        Quantitative Factors  	;	27
        Non-quantitative Faaors ,  	•	•	««	27
        Combining Quantitative and Non-quantitative Factors	28

Step6:  Combine Cancer and Non-cancer Risks	•	30

   2.2.1  Advantages and Disadvantages of Different Types of Data	:	4
   2.2.2 EPA Weight-of-Evidence Guidelines	•	7
   2.2.3 Sample Summary Table of Cancer Risks for Three Problem Areas	17
   2.2.4 Ranking of Non-cancer Health Effects	•'••	20
   2.2.5 Possible Health Effects Classification System'	21
   2.2.6 Sample Summary Table of Non-cancer Risks for Three Problem Areas...	24
   2.2.7 Cancer-Risk Ranking Groupings 	.7	....26
   2.2.8 Non-cancer Risk Ranking Groupings  .;	•.	....29
   2.2.9 Summary Matrix of Cancer and Non-cancer Effects........	31
   2.2.10 Combining Cancer and Non-cancer Effects	32

   2.2.1 Dose-Response Curves at Low Doses	-	--8
   2.2.2 Typical Dose-Response Curve for Non-carcinogens	<10
   2.2.3 Sample Summary Chart of Cancer Effects	:..-	18
   2.2.4 Sample Summary Chan of Non-cancer Effects	.24

 REFERENCES	•	•.	............33
 22-2                                                             September 1993

                                              2:2 Assessing Environmental Risks to Human Health
        Risk is the probability of the occurrence of adverse effects. Adverse health effects are
        caused by exposure to harmful-substances and can vary widely, ranging from
        lethal effects to more subtle biochemical, pathological, or physiological effects.
 Risk can be expressed quantitatively (probabilities ranging from zero to one) or non-quan-
 titatively (low, medium, or high). To estimate the magnitude of the problem, the estimat-
 ed risks to individuals can be multiplied by the estimated number of people exposed to the
 substance. EPA has defined human health risk assessment as:
         Evaluating the toxic properties of a chemical and the conditions of human exposure to it
       in order both to ascertain the likelihood tint exposed humans will be adversely affected, and
               to characterize the nature of the effects they may experience (NAS 1983).
   The traditional risk assessment process is comprised of four interrelated phases:
      Phase 1:     Hazard Identification—evaluating available evidence on the presence
                 . and hazards of substances likely to cause adverse effects.
      Phase 2:     Dose-Response Assessment— determining the degree of the effects at dif-
                  ferent doses.             ;                     '
      Phase 3:     Exposure Assessment—estimating the magnitude, duration, and fre- •
                  quency of human exposure to pollutants of concern and the number of
                  people exposed via different pathways.
      Phase 4:     Risk Characterization—combining the information obtained from"the
                  hazard identification, dose-response assessment, and exposure assess-
                  ment to estimate the risk associated with each exposure scenario con-
                  sidered, and to present information on uncertainties in the analysis to
                  risk managers.           } '             '  ,.   ,-/.'•

RISK ANALYSES                    _   I
   Comparative risk analyses involve an additional component to risk assessments that
entails comparing risks across problem areas to arrive at a relative ranking of the human
health risks posed by the various problem areas. Since it is not usually feasible to conduct .
risk assessments for all pollutants and pathways associated with each problem area, com-
parative risk analyses have typically involved the following six steps:  \
   •  Selecting hazardous substances that are representative of those posing health risks for
     each problem area.                    |                     j
   •  Identifying typical exposure scenarios for the selected substances associated with each
     problem area.                         j
   •, Calculating risks for those exposure scenarios using standard methods and readily
     available data on hazards and dose-response relationships.
   •  Extrapolating results for selected substances and exposure scenarios to the entire
     problem area.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
   •  Comparing information on cancer and non-cancer risks for different problem areas
     to establish human health rankings.
   *  Combining cancer and non-cancer risks.
   However, applying the risk assessment framework to comparative risk projects is not
always a clear step-by-stcp process. It is more typically an iterative process in which the
various phases are interrelated. For example, exposure pathways must be considered in all
phases of the comparative risk assessment. In the hazard assessment phase, the potential
hazards of pollutants are related to the likely exposure pathways, and the dose-response
and exposure concentration of a particular substance depend on the route of exposure.
   In addition, while standard methods for assessing cancer risks exist and can be directly
applied to the comparative risk analyses, methods for assessing non-cancer risks ,and com-.
bining cancer  and non-cancer risks are not well established. In adopting methods to indi-
vidual problem area analyses, it is important to keep in  mind the overall objective of the
project, consistency among approaches to different problem areas,  the time and resources
available, and  the analytic expertise of the staff.
   The methods used to analyze problem areas are likely to vary because the types of data
available vary.  For example, if incidence data are available, then the response can be directly
identified with no real need for traditional dose-response and exposure assessments.
Similarly, if existing studies can be used to infer risks for a particular problem area, then the
process is greatly simplified. There are basically three types of data that are commonly used
in comparative risk projects: incidence data, data  from other studies, and data from  risk
assessments. Table 2.2.1 lists the advantages and disadvantages of these three types of data.

                                    Table 2.2.1:
              Advantages and Disadvantages of Different Types of Data
Types of Data
Incidence data
Data from other
Risk assessment
Provides direct measure of
adverse health effects.
Eliminates need for risk
Reduces time, resources, and
expertise required to generate
risk estimates.
Provides a direct measure of
environmental ambient
conditions and exposures.
Not available for all problem
areas. Cause and effect
relationship is not always clear.
Ambient concentrations, types
of pollutants, and exposures
may be very different and
Assumptions and uncertainties
of models used can be large.
More data and resource
   Data on actual incidence of diseise related to a given problem area are generally prefer-
 able to estimating risk based on exposure concentrations and assumptions about intake,
 potency, and the exposed population. For example, state studies may provide information
September 1993

                                               2.2 Assessing Environmental Risks to Human Health
 on the statewide incidence of lead poisoning, or hospital admission data may provide esti-
 mates of the annual number of cases of pesticide poisoning in agricultural areas. These
 types of data can provide direct measures of human health effects, eliminating the need for
 extensive dose-response and exposure assessments. They also provide a better indicator of
 potential health impacts than exceedances of estimated safe levels. However, incidence
 data are not likely to be available for many problem areas. A related potential difficulty in
 usirig incidence data to characterize risks is that in many cases the data will not represent
 the geographic area in question, but instead a portion of the total geographic area or a  •
 broader area. In such cases, extrapolation or interpolation would be necessary to estimate
 the incidence for the relevant area. Another problem with using incidence data is that the
 relationship between cause and effect may not be clear.  For example, lead poisoning can be
 caused by many sources of lead in the environment, including soil, drinking water, air,
 and lead paint. If an analyst Is interested in knowing the risk of lead poisoning due to con-
 taminated drinking water, then incidence data will not provide a satisfactory answer given
 the many potential sources.                  I                          - .
    For some problem areas, it may be appropriate to use existing studies from other states
 or countries to estimate either exposure or incidence. In many past state comparative risk
 studies, states have applied regional or national studies to estimate the risk to the popula-
 tion of their state. Because existing studies are likely to represent conditions in'geographic
 areas other than those under consideration, actual pollutants arid exposure conditions may
 be different from those analyzed in the existing studies.  This presents difficulties in inter-
 polating and extrapolating from existing studies to the relevant geographic area. The
 advantage of using existing studies to estimate risks is the reduction of time, resources, and
 expertise required. Existing studies should be reviewed critically to determine their rele-
 vance to the analysis at hand;            •    \   •:''.-.
   The third and most traditional approach to analyzing risks associated with  particular
 problem areas is to estimate risks based on site-specific analyses of pollutants and expo-
 sures and, if necessary, adjust the results to estimate risks for that entire environmental
 problem. Monitoring data that indicate the ambient concentration of pollutants released
 into the environment typically serve as the basis  for estimating human health risks. For
 example, past studies have estimated risks associated with a sample of representative haz-
 ardous waste facilities (e.g., landfills, incinerators), identified the number of facilities rep-
 resented by each sample facility, and scaled up the estimated risks accordingly to provide a
 rough approximation of the total risk posed by hazardous waste facilities.
   The advantage of this approach over the use of incidence data or existing studies is that
 it provides a direct assessment of existing pollutants and exposure conditions, rather than a
 questionable extrapolation of data derived under potentially different exposure conditions.
The disadvantage of this approach is that typically it is more data and resource intensive.

   The first phase in human health risk analysis is identifying the hazard or potential risk.
It is an initial screening step that broadly examines all possible sources, pollutants, and
             	|	. .^ __-.	_i           ,                 '
September 1993                            i                                   2.2-5

A Guidebook to Comparing Risks and Setting Environmental Priorities
exposure pathways and identifies target pollutants, relevant exposure pathways, "and
adverse health effects associated with the pollutants and exposure pathways. Thus, it
frames the scope of analysis for each problem area analysis.

Target Pollutants
   Most environmental problems involve many hazardous substances. A comprehensive
assessment of the risks from all toxic substances for each problem area would be unwork-
able in the context of comparative risk analysis, because of the size of the analysis and the
resources required, and because of inadequate data on potentially hazardous substances.
Therefore, the analysis of each problem area needs to be focused on a limited number of
chemicals that best represent the actual risks.                          ,-.'..
   A generic set of criteria for selecting target pollutants for comparative risk studies has
not been developed. Primary factors to consider in selecting target pollutants include the
inherent toxicity of the substance, its prevalence in the environment, and the likelihood of
exposure. Information on structure-activity relationships, results of toxicity and biomoni-
toring tests, clinical studies, and  epidemiology studies should all be evaluated as a basis for
determining whether exposure to a substance can result in adverse health effects.
Secondary factors include the availability of data needed to assess the risk posed and the
level of regulatory concern for a particular substance.
   In past comparative risk studies., the selection, of target pollutants has been driven large-
ly by the.availability of data and expert judgment (which itself is a function, of data avail-
ability and regulatory concern). Due to limited data and resources, many past studies have
relied on too few target pollutants to adequately assess the risks _(EPA 1990). Limiting tar-
get substances to less than five for problem areas with many pollutants introduces analytic
biases that are very difficult to control and may be overlooked in the final ranking of prob-
lem areas. If such biases cannot be avoided by comprehensive hazard identification, then
they need to be acknowledged and addressed on a case-by-case  basis, adjusting the results
to account for the unanalyzed portions of the problem wherever possible.

Relevant Exposure Pathways                             .
    Exposure to environmental pollutants can occur via many pathways and most problem
 areas involve more than one exposure pathway. Comparative risk analyses typically focus
 on exposures from ingestion of contaminated drinking water or soil and inhalation of con-
 taminated air. However, ingestion of food contaminated by various means (deposition,
 plant uptake, bioaccumulation)  and  skin absorption by contacting contaminated surface
 water, shower water, soil, and air are important routes to consider. The exposure assess-
 ment can narrow the scope of exposure  routes analyzed by focusing on those that clearly
 dominate others in the magnitude of potential risb that they pose.

Adverse Health Effects
    Adverse health effects associated with target pollutants and exposure pathways are used
 to measure the severity of trie effect. Adverse health effects can be divided into two groups:
 2 2_<                                                               September 1993

                                               2.2 Assessing Environmental Risks to Human Health
  cancer effects and non-cancer effects. Determining whether a substance poses a carcino-
  genic risk to' humans is based on evidence from human epidemiological studies and long-
  term animal studies, as well as on other relevant information. EPA has developed*
  weight-of-evidence approach to classify the likelihood of human, carcinogenicity. EPA's
  Integrated Risk Information System (IRIS) provides information on the weight-of-evi-
  dence groups for substances that have been evaluated by EPA Based on human and ani-
  mal evidence, supporting data, and data quality, substances are classified by EPA into one
  of the five groups described in Table 2.2.2 (EPA 1986).  -

                                    Table 2.2.2:
                       EPA Weight-of-Evidence Guidelines
Group A:
Group B:
Group Bl
Group B2
Group C:
Group D:
Group E:
Human carcinogen ' \
Probable human carcinogen
Indicates limited human evidence
Indicates sufficient animal evidence i
inadequate or no human evidence
Possible human carcinogen <
Not classifiable as to human carcinogeni
Evidence of non-carcinogenicity
   Exposure to a given substance may result in a variety of non-carcinogenic toxic effects,
 depending on the dose. These may range from lethal effects to more subtle physiological
 changes. The toxic effects of a substance can vary with the magnitude, frequency, and.
 duration of exposure, and the information needed to characterize the risks associated with
 particular exposure conditions. IRIS also contains information on non-carcinogenic health
 effects for some substances (EPA 1988). The effects from all available studies are consid- .-
 ered in IRIS, but primary attention is given to die effect exhibiting the lowest "No
 Observed Adverse Effect Level" (NOAEL), the "critical effect." As discussed in the follow-,
 ing section on dose-response assessment, this is the effect associated with EPA's estimated
 maximum safe levels (reference doses) for non-csircinogens.
                                                         '       '
                     ,                                             .
   The relationship between the dose of a substance and the likelihood that it will produce
an adverse health effect is essential in assessing die risk associated with acposures to haz-
ardous substances. This relationship represents a substances potency. EPA typically makes
two general assumptions about dose-response relationships for particular substances:
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
   •  For carcinogenic effects, it is assumed that effects can occur at any dose, which are
     initiated by alteration of genetic material.
   •  For non-carcinogenic effects, it is assumed that threshold levels exist below which no
     adverse health effects will occur.
   Because of this fundamental difference in the assumed dose-response relationships for
carcinogens and non-carcinogens, the two are discussed separately below.

Dose-Response Functions for Carcinogens
   Although the mechanisms of carcinogenesis (i.e., the alteration of genetic material) are
not well understood for most chemicals, existing scientific evidence suggests that there is
some probability of effect at any dose and that the cumulative probability of effect increas-
es with increasing dose. Because the probability is low at low doses, it cannot be measured
.directly by cither animal or epidemiological studies. Therefore, mathematical models have
been developed to extrapolate from high.to low doses. Extrapolation procedures typically
define an upper bound by assuming linearity at low doses;  EPA uses the linearized multi-
stage model. Exhibit 2.2.1 presents a typical linearized multistage dose-response function
along with other dose-response functions.                      ,
Determination of Cancer Potency Factors
   Based on modeled dose-response functions, EPA has developed "cancer potency fac-
tors" and "unit risks" for many suspected carcinogens. Comparative risk analyses have typ-
ically used these potency estimates to assess the risks associated with exposures to carcino-
gens. Cancer potency factors (CPFs) express potency in terms of the risk per unit dose
 (milligram per kilogram of body weight per day, (mg/kg/day)), assuming lifetime expo-
sure. CPFs are sometimes referred to as slope factors, as they are the slope of the dose-
 response curve. To estimate risk using CPFs, the CPF is multiplied by the estimated dose
 (or the concentration times the intake).
                                    Exhibit 2.2.1:
                           Dose-Response Curves at Low Doses  	
                                                 Linearized Multistage Model
                                                   (upper confidence limit)
                                      -Increasing Dose
                                                                      September 1993

                                               2.2 Assessing Environmental Risks to Human Health
     Dose-response measures.are also expressed in terms of risk per unit of concentration.
  These measures are referred to as unit risks and are multiplied by the estimated exposure
  concentration to calculate risk. The unit risk for air inhalation is expressed in terms of risk
  per microgram of toxin per cubic meter of air; whereas the unit risk for drinking water is
  expressed in terms of risk per microgram per liter of water. EPA's unit irisk values assume
  an average body weight of 70 kilograms, an average inhalation rate of 20 cubic meters per
  day, and an average drinking water intake of 2 liters per day.
     EPA's established CPF and unit risk values reflect the upper 95 percent confidence limit
  of the dose-response function estimated using the linearized multistage dose-response
  model. They do not account for the uncertainty inherent in the use of experimental ani-
  mal data to estimate human,responses. However, as long as these types of extrapolation
  assumptions are consistent for all pollutants and problem areas, the results provide a rea-
  sonable reflection of relative differences in risk as required in comparative risk analyses.
  Availability of Cancer Potency Factors       j
    EPA has-established CPF and unit risk values for many chemicals that are common
  environmental pollutants. However, the list is by no means complete and is largely driven
  by the availability of toxicity data. The established CPF and unit risk values are available
  in IRIS, which is accessible on EPA's Electronic Mail or can be purchas<:d from the
  National Technical Information Service (EPA 1988b). In addition, EPA's Carcinogen Risk
 Assessment Verification Work Group has proposed CPFs for chemicals not yet  included in
 IRIS. If-these sources do not provide CPFs for chemicals of interest in the comparative
 risk analysis, dose-response functions and their implied CPFs could be developed from
 animal toxicity data. In the past, however, this has  been beyond the Scope of comparative
 risk studies, and substances without established or  proposed CPFs have not been evaluated
 for carcinogenic risk. If the expertise and resources are available to estimate dose-response ;
 functions from original animal or epidemiological data, it is important to ensure that the
 assumptions used are consistent with those used for generating other risk estimates.

 Dose-Response Functions for Non-carcinogens               /
   For biological effects other than cancer, EPA generally assumes that a threshold dose
 exists below which no effect will occur. Thus, the threshold is the minimum dose neces-
 sary to cause an adverse biological effect. The probability of an adverse effect occurring
 increases as the dose increases above the threshold level. However, the dose-response rela-
 tionship above the threshold varies for different substances and types of exposures and is
 not well characterized for many substances.                   ' •'   • \
   For some non-carcinogenic substances, epidemiological data are available for certain
 exposure pathways.  Studies of human health, effects associated with criteria air pollutants,
 for example, have provided estimates of the number of cases of adverse health effects per
 unit concentration of ozone or paniculate matter (EPA 1988a). Such estimates can also be
 used to estimate the expected incidence of adverse health effects.
September 1993                              j                                 22-9

A Guultbock to Comparing Risks ami Setting Environmental Priorities
Determination of the Reference Dose
   In the absence of epidemiological data that characterize the dose-response relationships
for non-carcinogens, an estimate of the threshold dose is typically used. Exhibit 2.2.2 pre-
sents a typical dose-response function for non-carcinogens (the threshold is designated by
T). The threshold dose for a substance is approximated by the NOAEL, which is the high-
est dose at which no effect has been observed in toxicological experiments. A single chemi-
cal may exhibit more than one adverse effect, and the NOAELs for these effects may dif-
fer. The NOAEL for the health effect exhibiting the lowest NOAEL is typically used as
the basis for estimating a maximum safe level.

                                   Exhibit 2.2.2:
                Typical Dose-Response Curve for Non-carcinogens	
       of Adverse
     Health Effects
                                       -Increasing Dose
  •  EPA typically develops a safe level, referred to as a "reference dose" (RfD), by dividing
 the NOAEL by an uncertainty factor, thus, the RfD will always be lower than the NOAEL.
 Uncertainty factors are based on the type and quality of the data from which the NOAEL
 was derived, and reflect the degree of confidence in the data as indicators of the human
 health effects of a substance. The RfD is defined as "an estimate (with uncertainty spanning
 perhaps an order of magnitude) of daily exposure to the human population (including sen-
 sitive subgroups) that is likely to be without an appreciable risk of deleterious effects during
 a lifetime" (EPA 1991). It is expressed in milligrams of substance per kilogram of body
 weight per day. In effect, RfDs are<»nservative estimates of threshold levels and are typical-
 ly used as relative measures of the potency of exposure concentrations. As the magnitude of
 exposures exceeding the RfD increases, die probability of adverse effects increases.
 Therefore, the greater the RfD exceedance, the greater the human health risk.
    It is important to note that RfDs (unlike CPFs) do not indicate the probability of
  adverse effects above the threshold; that is, one cannot extrapolate on a scientific basis
                                                                    September 1993

                                               2.2 Assessing Environmental Risks to Human Health
  between RfD exceedances and probability of effect. The dose-response relationship above '
  a threshold level may be very different for different substances and types of exposures, bur
  typically it is not well characterized or available for non-carcinogens. As a result, RfDs do
  not enable one to estimate risks at exposures greater than the RfD.   ••'..*
     Despite this serious limitation of the RfD approach to characterizing the dose-response •
  relationship for non-carcinogens, EPA endorses .this method in its guidelines for quantify-
  ing non-cancer health effects (EPA 1991). In both Unfinished Business (EPA 1987) and all
  of the regional comparative risk studies, doses estimated from exposure concentrations were
  compared to RfDs (or somecomparable standard) to characterize the risks associated with
  chemical exposures. The number of people exposed to doses exceeding RfDs was used to
  characterize population risks. Although other methods are currently under development,
  none is widely applied due to the preliminary nsiture and lack of data to support them.
  Availability of Other Maximum Safe Levels.  !                     !
    EPA has established RfDs for many chemicals that are common environmental pollu-
  tants. However, the list is not complete and is largely driven by the availability of toxicity
  data. The established RfDs are available in EPAs IRIS. In addition, EPA's Reference Dose
  Work Group has  proposed RfDs for chemicals not yet included in IRIS. If RfDs are not
  available for chemicals of interest in comparative risk analyses, other regulatory standards
  that represent maximum safe levels can be used. In the past, EPA regions have used maxi-
  mum contaminant levels (MCLs), ambient air quality standards, and threshold limit val-
  ues (TLVs).                               .  i '               ••-.-.
     f            .           •                • i         -•'.••',"      '       ; .
    It is important to exercise caution in using alternative regulatory levds, since different
 standards may represent different degrees of conservatism. Inconsistencies in the bases of
 different regulatory levels should be adjusted for when interpreting results across sub-  '
 stances and problem areas. For example, MCLs  are not based solely on health considera-
 tions, but can include consideration of feasibility (cost and available technology). As a
 result, they, may be less stringent than the health-based RfDs. Similarly, TLVs, developed
 for occupational exposures, are less protective than other health-based standards for gener-
 al population exposures. It may be beyond the scope of the comparative risk analyses to
 make chemical-specific adjustments that put all  threshold levels on a consistent basis, but
 the uncertainties associated-with the use of maximum safe levels other than RfDs should
 be noted and factored into the final analysis.     f           • -            '

 STEP 3: ASSESS EXPOSURE               |
   Exposure scenarios estimate the magnitude, duration, and frequency of exposure; the
 number-of people  exposed; and the intake of the substances to which people are exposed.
 These estimates can be generated directly from monitoring data of contaminant  levels
 measured in the ambient environment and in biological organisms, or indirectly from
 modeling results or reasoned estimates. The steps involved in exposure assessment are:
   •  Identify significant exposure'pathways.
   •  Identify sources and the location, timing, and quantity of pollutants released.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
   •  Describe the concentrations of pollutants in the environment to estimate exposure.
   •  Describe potential human contact to estimate the number of people exposed to vari-                  .
     ous concentrations via different pathways.                                               .
   •  Estimate human uptake via relevant exposure routes.
   By evaluating these components of exposure, the analyst can construct reasonable sce-
narios for each problem area that characterize exposures to different populations. Exposure
components are similar for both carcinogens and non-carcinogens.

Exposure Pathways
   Humans are exposed to pollutants through ingestion, inhalation, or skin absorption.
Activity patterns largely determine the routes of exposure. Standard assumptions that are
used include the consumption of two liters of water per day and 20 cubic meters of air
inhaled per day for the average adult. In actuality, studies have shown that there is a great
deal of variability in these rates (EPA 1983, 1985). However, due to the relatively impre-  .
cise nature of comparative risk analyses and the magnitude of the uncertainties associated
with other components, the degree of variability associated with intake assumptions may
have a relatively minor effect on the overall results.                           :                                ,
   Most problem areas involve more than one pathway of exposure. To confine the'scope
of the analysis, the exposure assessment should identify the exposure pathways considered          .   ,       -
most important. For some problem areas, this may be straightforward. The primary expo-                      J
sure route for indoor air pollutants, for example, is inhalation. For other problem areas,
such as hazardous waste sites, it may not be possible to limit the analysis to one pathway if
the potential exists for exposure through drinking water, air, and direct contact. Many of
the regional and state comparative risk studies focused attention on direct inhalation and
ingestion exposures,  and did not recognize less direct exposures. It is important to note
that many comparative risk projects simplified the analysis by addressing less significant
exposure pathways non-quantitatively and factoring them  into the ranking process.
   A complicating factor in the identification of relevant exposure pathways is that the
toxicity of some substances may vary for different exposure routes. For example, asbestos is
known to be carcinogenic via the inhalation route, but cannot be absorbed through the
skin and has not conclusively been shown to be carcinogenic if ingested (Casarett and.
Doull 1980). Therefore, in identifying relevant exposure pathways, it is important to con-
sider the toxicities of target pollutants via the different exposure routes under investiga-
tion. In the absence of relevant data on toxicity, metabolism, or absorption through differ-
ent exposure routes, it is often assumed that adverse effects from different exposure routes
are equivalent, but this assumption should not be made without proper consideration of
available data.

 Sources and Releases ofPottytion
   Information on the concentrations of released pollutants and their quantities is critical
 to estimating exposure concentrations, particularly where ambient monitoring data are

 22-12                                                             September  1993

                                              2.2 Assessing Environmental Risks to Human Health
 not available. In addition, the location and timing of releases provides information impor-
 tant to determining likely human contact. For example, leachate concentration data at  -
 hazardous waste landfill boundaries is used to estimate the potential ground-water conta-
 mination in downgradient drinking water wells. Data sources for release information will
 vary significantly for different problem areas,  i                     ;             " ,   •

 Fate and Transport of Pollution     •  \
    Fate (the final destination) and transport (the route the pollutant takes) determine the
 pollutant concentrations that people are likely to be exposed to. These concentrations can
 be estimated using monitoring data or modeling. Monitoring data are clearly the preferred
 option, since modeling is usually based on numerous assumptions and limited data and
 may not  provide accurate estimates of the concentrations to which people are exposed.
 Sophisticated mathematical modeling can also be resource intensive. Although monitoring
 data are preferable, this approach can also inaccurately predict human exposure levels, par-
 ticularly if the estimates are only based on a few measurements.       !
    In either case, it is important to consider the dilution/dispersion, mobility, persistence,
 and degradation of the substances rn the environment prior to exposure. If the fate and
 transport of pollutants are modeled from release to exposure, such factors are particularly
 difficult and- uncertainties increase due to the increased time and distance to exposure.
 Even if ambient concentration data are available, contaminant concentrations can change
 between the monitoring location and the exposure point. For example, drinking water
 concentrations at a drinking water treatment plant may not reflect concentrations at the
 tap, since other contaminants (e.g.,, lead) can be absorbed into the water in the distribu-
 tion system. Such factors merit  consideration in estimating exposure concentrations. In
 many comparative risk analyses, time and resources will constrain the use of sophisticated
 modeling of fate and transport, and reasoned assumptions will have to be made.

 Human Contact
   Estimating potential human  contact with environmental contaminants involves evalu-
 ating activities that could result in •contact, estimating the duration and magnitude of con-
 tact, and calculating the size and distribution of vulnerable populations, Using the expo-
 sure pathways defined for the analysis, this step identifies the numbers and types of people
 exposed and the range of exposures for each pathway. Census and survey data can be used
 to estimate the size of the exposed population.  ]            '
   In presenting information on the concentrations to which populations are exposed, it
 is important that the measures be consistent with the dose-response units used in risk cal-
 culations. Defining human exposures in terms of average daily exposures over a-lifetime
will enable the analyst to use dose-response data appropriate to chronic exposures.
Similarly,  acute exposure situations can be expressed in terms of average daily exposure
over a short period.
September 1993

 A Guidebook to Comparing Risks and Setting Environmental Priorities
    For most problem areas, there, will be a wide range of exposures, with some specific eth-
 nic or socioeconomic groups being exposed to greater contaminant concentrations than
. others. For example, pesticide applicators will be exposed to far greater concentrations'of
 pesticides than the general population. Similarly, people using private versus public drink-
 ing-water supplies may be exposed to different contaminants and concentrations.
 Behavioral  factors will also affect exposure. Time and location patterns vary'widely for dif-
 ferent individuals. For example, some people spend more time indoors than outdoors, and
 people in some areas swim more frequently than those  in other areas. In theory, for any
 chemical, there is a distribution of exposures that relates the size  of the exposed population
 to the exposure concentration. To the extent possible, comparative risk studies should
 characterize potential exposures by identifying at least several points in the exposure distri-
 bution (e.g., a measure of central tendency and values one standard deviation  above and
 below the median or mean value).
    Some people may be more sensitive to particular contaminants than others and may
 experience health effects at concentrations lower than those causing adverse effects  in the
 general public. In addition to integrating exposure and concentration distributions, the
 exposure assessment should attempt to evaluate the effects on highly sensitive populations,
 such as pregnant women, infants, or asthmatics. Another factor to consider is risk-mitigat-
 ing behaviors. People may be inclined to reduce their exposures if they know they are at
 risk. If, for example, drinking water concentrations of  benzene exceed taste or odor thresh-
 olds, some people will stop drinking the water, thus mitigating the potential risks.
 Consideration of these types of exposure variabilities will lead to more accurate risk esti-
 mates, but will not always be possible due to resource and data constraints. It is important
 to note that many comparative risk analyses have simplified the process either by not
 addressing all of the human contact issues for all problem areas or1 by only addressing
 them non-quantitatively.

     Estimating the exposure concentration, duration and timing of exposure, and the
  nature and size of the populatipn affected are critical factors for characterizing human
  health risks. In many instances, the information available to assess these factors will be
  very limited, and time and resource constraints may not allow for the extensive analysis
  required to accurately evaluate them. For this reason, many of the factors discussed in this
  chapter cannot be thoroughly evaluated in comparative risk projects (Finkel 1990).
     However, in almost all situations (particularly where data are limited and sophisticated
  analysis is not possible), the analyst will need to make various assumptions about and
 , approximations of exposure concentrations, numbers  of people  exposed, and intake levels.
  It is important that such assumptions be consistent across problem areas and reflect a simi-
  lar degree of conservatism. In most cases, it is possible on the basis of available data to esti-
  mate upper and lower bounds for exposure concentrations and numbers of people
  exposed. In some cases, statistical distributions can make it possible to do more sophisti-
  cated uncertainty analysis using Monte Carlo simulation techniques. At a minimum, a

  2 2 14                                                             September 1993

                                               •2--2 -Assessing Environmental Risks to Human Health
 semi-quantitative or non-quantitative assessment of the impact of exposure uncertainties
 on risk calculations should be incorporated into the ranking process.

    In comparative risk analyses, risk characterization is the essential link between risk
 assessment and risk ranking. This phase involve combining the information obtained
 from the hazard identification, dose-response, and exposure assessment phases. It involves
 presenting information oh .multiple contaminants and exposure pathways in a way that
 allows, decision makers to evaluate the relative risks posed by various problem areas.
 Because the risk characterization of carcinogens and non-carcinogens is different, they are
 discussed separately below.                         "

 Characterizing Cancer Risks
    The most useful presentations of cancer risk estimates for comparative risk studies are
 excess individual lifetime risks and the excess number of annual cancer cases expected in
 the exposed populations. Population risk is an estimate of the annual ameer incidence.
 While many regional and state comparative risk studies have estimated both individual
 risks and population risks, most have relied primarily on the population risk estimates in
 the final ranking of problem areas  for cancer risks. Both measures of cancer risk are dis-
 cussed below.                               ;
    In addition to numerical estimates of cancer risks, risk characterization helps risk man-
 agers judge the significance of risk estimates. In particular, information on the uncertain-
 ties associated with numerical estimates  is critical to making informed ranking decisions.
 A framework for presenting such information is also discussed below.
 Risk of Cancer to Individuals               '
   Individual cancer risk is based on information provided by the dose-response and expo-
 sure assessments. It is calculated  by multiplying the carcinogenic potency of the substance
 in question by the dose to the exposed individual:
              Individual Cancer Risk - Potency (CPF) z Dose (Concentration x Intake)
   The above equation assumes that the  potency is expressed in terms of risk per unit  dose
 (i.e., CPF), where the dose must be calculated based on the exposure concentration and
 the uptake or "delivered dose." If the potency is expressed in terms of risk per unit concen-
 tration (i.e., unit risk), then individual cancer ris;k is calculated by multiplying the potency
 by the exposure concentration. In this case, the potency estimate embodies assumptions
 specific to the route of exposure.         '
                 Individual Cancer Ruk - Patency ([Unto Risk) .x Concentration
   To illustrate the application of these equations, assume that an individual is exposed to
 0.04 micrograms of beryllium  per cubic  meter of air inhaled. Using the CPF for beryllium
 of 8.4 per milligram per kilogram,per day, and assuming an average intake of 20 cubic
 meters of air per day for the average 70-kilogrami adult, the calculation would be:
September 1993                             I,                             2.2-15

X Guidebook to Comparing Risks And Setting Environmental Priorities
            8.4 (mg/kg/day)-l 10.4 ug/m3 z 20 m3/day + 1 mg/1000 ug - 9.6 z 10-4
   If the EPA unit facror for beryllium.— 2.4 x 10-3 per microgram per cubic meter of air
— is used, then the calculation is simplified to:
                       2.4 x 10-3 (ug/m3)-l z 0.4 ug/m3-9.6 z 10-4
   Individual risks can be calculated for individuals in various population groups. At a min-
imum, the comparative risk analysis should estimate individual risks to the average-exposed
individual and the maximum-exposed individual. The average-exposed individual risk will
reflect exposures to the majority of the exposed population. The "maximum-exposed indi-
vidual risk will reflect exposures to individuals exposed at higher concentrations.
   If the same individuals are likely to be exposed to different carcinogenic substances or,
via different pathways, then die cancer risks associated with the concurrent exposures can .
be added to provide total individual risks for a given problem area. The assumption of
additivity is a simplification that does not reflect synergistic or, antagonistic effects that can
occur between different substances. If concurrent exposures to co-carcinogens, promoters,
or initiators are suspected, then they can be considered on a case-by-case basis.
Risk of Cancer to Populations
   Population cancer risk, sometimes 'referred to as cancer incidence, is also determined by
the dose-response and exposure assessments. It can be calculated by multiplying the indi-
vidual cancer risk by the number of people exposed:             ,
                Cancer Incidence - Individual Cancer Risk z Exposed Population
   This calculation can be made for specific populations and then summed to provide can-
cer incidence estimates for the total population. Air pollutants, for example, may pose
greater risks to urban populations than rural populations. In this case, cancer  incidence can
be calculated for the  urban and rural populations based on separate estimated exposure
concentrations and populations, and then added to provide the total jiumber of expected
cancer cases for all exposed populations. As with individual risks, the analyst can assume
additivity to combine population risk estimates for different substances and pathways.
Uncertainty                            .
   Presentation of numerical risk estimates without information on the assumptions and
uncertainties underlying them can be misleading to risk managers. Therefore,  it is important
that  such information be explicidy stated and considered in the risk characterization phase
of the analysis. Explicit discussion of uncertainties and interpretation of the numerical esti-
mates will provide die risk manager with insights into the accuracy and limitations of risk
estimates. Major assumptions, omissions, scientific judgments, and estimates of uncertainty
should always be included whenever characterizing risks. In addition, die appropriate
wcight-otevidence designation should accompany die numerical risk estimate for any car-
cinogenic agent, indicating the degree of certainty of a substance's carcinogenicity.
   For key factors, such as exposure concentrations and number of people exposed, uncer-
tainty can be estimated quantitatively by using ranges of estimates in addition to a best
2.2-16                                                    .          September 1993

                                               2.2 Assessing Environmental Risks to Human Health
 estimate. Providing a range of risk estimates to decision makers enable! them to determine'
 whether the magnitude of the uncertainty warrants changing the problem-area rankings.
 Presenting Cancer Risk Information to Decision Makers
    Decision makers consider several different types of information when establishing a
 cancer risk ranking of problem areas. This information can be summarized and presented
 to decision makers in different ways.                      t.
    One basic presentation tool is a summary table (see Table 2.2.3) that combines relevant
 information on cancer risks and the analyses performed to derive them, Table 2.2.3 pro-
 vides estimates of the average and maximum individual risks, total population risk or inci-
 dence, and risks to groups of highly sensitive individuals for each pathway, pollutant, and
 problem area. The comments column allows the analyst to communicate the limitation's
 of the analysis, the major uncertainties associated with the estimates, and any biases these
 uncertainties may introduce. The analyst may also wish to present an aggregated version
 of this table by consolidating information on different pathways and pollutants within
 each problem area. This could be done by presenting ranges for the individual-risk metrics
 that include different pathways and pollutants and by adding the incidence estimates for
 different pathways and pollutants within each problem area. If the individual risks associ-
 ated with different pathways and pollutants are experienced by the same people, they can
 be added to indicate the aggregated individual risks. Such a summary table should be used
 only to aid the ranking process and should not stand alone.
                                             i                     '    '
                                           Table 2.2.3:
                        Sample Summary Table of Cancer Risks for Three Problem Areas

Problem Areas
Air toxics
Surface water
(drinking sater)
Surface water
(fish consumption)

1.3 Butadiene



3 x 10*
3 x 10-»
5 x 10-5
5 x 10-6

0.00 '
laltfon Risk
'! —

Comments '
Expoiure concenmnoni biied on
1988 monitoring data from two urban
ami. AIR based* on minimum
r*Tfrfi concentrations; MIR based
on "•»j"""n r^r~4~\ concentration:
Bwed on monitoring data from three
drinking-wats' sources. May, not be
repreiaitaiive of state. •
Overestimate — auumei eoiire snue
popu]tfian expoced by consuming
20 pound! of fuh per year.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
   A second useful visual aid is a chart that combines information in a two-dimensional
space on the relationship between two or more factors, such as individual and population
risk. For instance, Exhibit 2.2.3 provides an example of a chart where each problem area is
represented as a coordinate where lifetime individual risk is shown on the horizontal axis
and annual cancer incidence is shown on the vertical axis. The coordinates indicate the rela-
tive risks posed by the different problem areas. It is important to note that the chart is sim-
ply a visual aid for presenting data to the ranking group and that the ranking itself should
include other factors, such as sensitive subpopulations and uncertainties in the analysis.

                                    Exhibit 2.2.3:
                      Sample Summary Chart of Cancer Effects
1 x 10-3 '
Average 1 x 10-4 •
1 x 10-5 •
Air toxics
. ^Drinking water
,Fish consumption

0.01 0.1 1.0 10.0 100.0
Total Population Risk
   A variation of Exhibit 2.2.3 could illustrate the uncertainties associated with cancer risk
 estimates by incorporating ranges for individual and population risks. This can be clone by
 drawing "bubbles" or "bands" around the point estimates. Visually presenting uncertainty
 in cancer risk estimates conveys the fact that reliance on best estimates is not sufficient to
 arrive at a ranking, or even a simple grouping of problem areas, since many problem areas
 will have risk estimates that  overlap other problem areas.

 Characterizing Nonrcancer Risks
   Past comparative risk analyses have characterized non-cancer risks according to three
   •  Severity of the health effects
   •  Ratio of the dose to the RfD (dose/RfD)
   •  Number of people potentially exposed
   Information on these three factors is generated in the corresponding first three phases
 of the risk assessment process. The risk-characterization phase involves summarizing and
 integrating this information into the incidence of adverse health effects for each problem
September 1993

                                               2.2 Assessing Environmental Risks to Human Health
 area. This integrated picture provides the basis for ranking problem arias. The result is a
 complete picture of the estimated risks to exposed populations and specific subpopula-
 tions, in addition to explicit consideration of the uncertainties and critical assumptions i
 those estimates. Following is a discussion of methods for summarizing information on the
 severity of health effects, the ratio of the dose to the RfD, evaluating etposed populations,
 and choosing approaches to integrating the information across pollutants and pathways
 within and across problem areas.             j
 Severity of Health Effects                   ;
   The hazard assessment phase identifies .the pollutants of concern for each problem area
 and the likely human health effects associated with exposure to those substances. In some
 cases, one substance may cause more than one health effect, or the severity of the health
 effect may vary with the dose of the substance. For example, cadmium can cause kidney
 dysfunction at low doses, kidney degeneration at higher doses, and binih defects at even
 higher doses. Rather than consider multiple effects for each pollutant, she analysis,can
 focus on the effects that drive regulatory concern. In the case of non-csircinogens, this is
 the adverse effect that occurs at the lowest dose and is the critical endppint on which the
 RiDs are based. The severity of this effect should correspond to the level of the estimated
 exposure concentrations. •          '          j                          .
   Characterizing the severity of health effects is invariably controversisil. Various severity
 scales have been developed,  and most are highly subjective. The factors to-consider in
 developing severity scales, or evaluating existing; ones for use in comparative risk analyses,
 include functional effects, welfare effects, and die nature of the illness in terms of viability,
 reversibility, and manageability. Different scales emphasize different factors, and there is
 no universally accepted approach.
   The approach developed  for Unfinished Business (EPA 1987) classifies health effects
 according to their threat to the viability of organisms. A seven-point severity scale was
 developed as a guide to scoring the severity of health effects. The health effects and their
 position in this scale are presented in Table 2.2.4. The ultimate severity scores, however,
 took into consideration non-quantitative judgments about the extent to which health
 effects were permanent, reversible, and manageable. The severity scale was reduced to four
groups for the final scoring.                  . i
   One regional EPA project collapsed this scale even more by assigning all health effects
to either high- or low-severity groups. The high group consisted of life-threatening effects,
such as severe mental retardation and heart attack. The low group consisted of all other
effects. The problem with this approach is that the range of health effects represented by
low severity is very broad; thus, differences in effects, such as nasal irritation and emphyse-
ma, were not distinguished in the final  ranking. Severity scales used in comparative risk
analyses should ideally distinguish effects more finely than this. Others have suggested
designating non-cancer health effects using three categories of severity: catastrophic, seri-
ous, and adverse. Table 2.2.5 provides an example of how this approach, might classify dif-
ferent health effects into these three categories for ranking purposes. The placement of
September 1993                             |                                 2.2-19

A Guidebook to Comparing Risks and Setting Environmental Priorities
health effects in Table 2.2.5 is only for illustrative purposes and does not imply a recom-
mended categorization, and the assignment of health effects into categories is likely to
spark considerable debate.
Table 2.2.4
Ranking of Non-cancer Health Effects
Specific Effects
Increased heart attacks
Aggravation of angina
Increased blood pressure
Abnormal ossification
Low birth weight
Decreased heme production
Bone marrow hypoplasia
Impaired heme syndiesis l
Allergic reactions
Increased infections
Tubular degeneration
Necrosis '
Nasal irritation
Pulmonary irritation
Nasal ulceration
Mucosal atrophy
Pulmonary impairment

7 '

. 4

' 4


• 3
3 '

Specific Effects
Hepatitis A
Increased weight
Increased enzymes
Hereditary disorders
Cytogcnctic ,
Sensory irritation
Reduced corneal sensitivity
Retinal disorders
Visual aging
AChe inhibition
Learning disabilities
' Decreased sensory perception

Post-implantation losses
Testicular degeneration
Spermatocyte damage
Decreased cesricular weight
Uterine hypoplasia
Increased resorptions



4 -

September 1993

                                              2.2 Assessing Environmental Risks to Human Health

Specific Effects
Lung injury
Pulmonary edema
Pontiac fever
Hemorrhage ;
Alveolar collapse
Fibrosis • ,
Nasal cellular irritation
Lung structure changes
Aggravation of asthma
Increased respiratory disease
Decreased mid-expir. flow rates
Increased respiratory infections
•* ' * '• - ' 5 , ' ' . ' " . -
of Noa-cajicer Health Effects
Score ;
(1-7) i Specific Effects
4 Giant cell formation
5 Increased spontaneous abortions
5 " Unspecified organ effecis
3 ! Unspecified acute effects
- 4 ',:, Mortality
5 Eye irritation
5 Dental erosion
2 ! Cataracts
5 Leishmaniasis
4 , Adrenal
4 Gastrointestinal disease
4 Bone damage, dental mottling
3 •' Symptomatic effects (headache)
4 Legionnaires' disease


2 -
: —
                                    Table 2.2J:
                    Possible Health Effects Classification System
Shortened life span
Severe disability
Mental retardation
Hereditary disorder
Organ dysfunction
Nervous system
dysfunction j
dysfunction j
Behavioral dysfunction
Loss in body weight
Enzyme changes
, Reversible organ
Ratio of Dose to RfD         ~

   Risks posed by non-carcinogens are typically characterized using the ratio of the dose of

the pollutant to the RfD. This ratio is sometimes referred to as the Individual Exposure
Ratio (IER):                                 |                     ".[•

September 1993

A Guidebook to Comparing Risks ami Setting Environmental Priorities
   The IER represents the degree to which the dose of a hazardous substance exceeds the
estimated safe level, and it roughly correlates with the probability of adverse effects at
doses above the RfD. The greater the dose is relative to the RfD, the higher the ratio, and
the higher the probability of adverse health effects. To calculate the IER, both the dose
and the RfD  must be in the same units since the ratio is dimensionless. This is typically
accomplished by converting the exposure concentration (expressed in milligrams per liter
of drinking water, gram of soil or food, or cubic meters of air) into a dose (expressed in
milligrams per kilogram of body weight per day) using standard intake and body weight
assumptions as illustrated in the  following equation:           .   '    .
                       Dose - Concentration z Intake + Body Weight
   For example, a methylene chloride concentration of five milligrams per liter in drinking  ,
water can be converted to an average daily dose, assuming an average drinking water intake of
two liters per day and an average body weight of 70 kilograms, using the following equation:
                        5 mg/1 x 2 L/day r 1/70 kg - 0.14 nig/kg/day
   The  reference dose for methylene chloride is 0.06 mg/kg/day; therefore, the estimated
dose exceeds  the reference dose by  greater than a factor of two:
                            0.14 mg/kg/cl'. + 0.06 mg/kg/d • 2.38
   There are important conceptual problems with using the IER to indicate the likelihood
that an  effect will occur above a ratio.of one. First, using lERs to compare the risks associat-
ed with different chemicals implicitly assumes that the dose-response function for all sub-
stances  is the same. That is, an IER of 2.38 for methylene chloride is equivalent to the same
IER for all other substances. This clearly is not the case, as some substances may have a high
probability of effect at this level while for others the effect may be negligible. This is due to
the different responses of various chemicals, and different safety factors that are incorporated
into the RfD. A second problem with the IER is that the assumed dose-response function is
linear and indefinite whereas a true dose-response function would more likely be asymptotic,
and the probability of the effect happening approaches one as the dose increases. As a result,
using the IER as a relative measure  of potency may lead one to make inappropriate distinc-
tions between the potencies of different substances at high exposure levels. EPA recognizes
these shortcomings and is currently developing alternative methods. However, toxicity data
on non-carcinogens do not currently support biologically based human dose-response mod-
els at doses above some threshold such as the RfD (EPA 1991).
Evaluating Exposed Populations
   Most comparative risk studies arc unable to fully characterize the exposure distributions
due to  a lack of data or limited resources available to model the distributions. However,
studies should attempt to describe at least several points on the distribution and, in partic-
ular,  identify the population subject to potentially high exposure concentrations. In theo-
ry, for any chemical there is a distribution that relates the size of the exposed population to
the exposure concentration. In general, there are large numbers of people exposed to low
concentrations and smaller numbers of people exposed to higher concentrations. For
 example, urban populations may experience greater risk to certain air pollutants than rural

 2 2_22                                                               September 1993

                                              2.2 Assessing Environmental Risks to Human Health
 populations. In this case, exposure concentrations and the number of people exposed
 should be specified for each subpopulation.   ;
   In addition, sensitive subpopulations (e.g., infants, pregnant women, and the elderly)
 should be identified, particularly in cases where the sensitive subgroup 'may comprise the
 only people in the exposed population who are at risk of suffering the adverse health
 effect. For example, children may be the only people at risk of lead poisoning from soil
 ingestion, or asthmatics may be the only people at risk from exposure to low concentra-
 tions of ground-level ozone (i.e., smog). To fully characterize the risks associated with each
 problem area, these sensitive subpopulations should  be specified.
   Knowing the number of people exposed to a particular contaminant is critical to char-
 acterizing population risks  and is often difficult to estimate. Census data can be used to
 identify and describe exposed populations where more accurate state or local data are not
 available. Whatever information is used is likely to be somewhat uncertain. Therefore, to
 characterize the uncertainty, it is best to characterize exposed populations using ranges of
 population estimates.                       j                     ;
 Presenting Non-cancer Risk Information to Decision Makers
   As suggested by the preceding discussion, decision makers must consider many differ-
 ent pieces of information when establishing this non-cancer risk ranking. Ways of summa-
 rizing and presenting this information to decision makers to ensure that all relevant factors
 are taken into account are presented below. The ideas given here are merely suggestions;
 analysts should develop tables, charts, and other materials  that best communicate the non-
 cancer risk information to decision makers,   j                            :
   One basic presentation tool is a summary table that gathers together relevant informa-
 tion on non-cancer risks. Table 2.2.6 provides hypothetical estimates of the dose/RfD
 ratio, the number of people at  risk, and the severity rating of the health effect for each pol-
 lutant, pathway, and problem area. The comments column allows the analyst to commu-
 nicate the limitations of the analysis, the major uncertainties associated with the estimates,
 and the biases these uncertainties may introduce. The analyst may also wish to present an
 aggregated version of this table by-consolidating information on different pollutants, with-
 in each problem area. This  could be done by piresenting ranges for the dose/RfD ratio,
 population at risk, and severity. Alternatively, the estimates for each of the factors could be
 added or averaged as indicators that represent the entire problem area. A third approach
would be to select the pollutant thought to pose the greatest risk or only those pollutants .
with IER ratios of greater than one. In any case, an aggregate summary table should be
 used only to aid the ranking process and should not stand  alone.
   Another useful visual aid is a chart that combines  information on several factors in a
two-dimensional space. Exhibit 2.2.4 below on non-cancer health effects is analogous to
 Exhibit 2.2.4 on cancer health" effects. Exhibit 2.2.4 shows three problem areas as coordi-
 nates on a chart, where the  severity ratings are shown on the horizontal axis and the esti-
 mated IER is shown on the vertical axis. The shape and shading of the points represent
the estimated number of people at risk for each problem area.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
                            Table 2.2.6:
     Sample Summary Table of Non-cancer Risks for Three Problem Areas
Problem Areas
Air toxics
Surface water
(dnrJong water)
Surface water
(fish consumption
0.00 - 0.02
0.02 - 0.03
1.14 -2.21
2^1 - 3.42
0.01 - 0.29
at Risk
Pneumonitis (4)
Pneumonitis (4)
Neuropathy (3)
Cyst formation
in liver (3)
Renal cytomegaly (3)
Liver lesions (3)
Liver hypotrophy (3)
Exposure concentrations based on 1988
monitoring data from two urban areas.
Dosc/RfD range based on minimum and
maximum recorded concentrations.
Based on monitoring data from three
drinking- water sources. May not be .
representative of state.
Overestimate— assumes entire state
population exposed by consuming 20
pounds of fish per year.
Noa U"oaen«atie» uioctxd wuh csomitci of doK/RtD ind populitioo cm be illuitrtied equity well in i able or dun. By incorporttmf imcetuinty Tjtiuto" or "bubbles," either i
(life cc • dbjut cu toovey lie fia tbu relacco on poinl eaimua it not nifficiett to tirive u i nafciaf fince miny problem ueuwiU hive cRinuie«thiiovulip with other problem
• ««•! Krt«'«-*l^^t ' =
                                   Exhibit 2.2.4:
                    Sample Summary Chart of Non-cancer Effects
• Drinking water Population Groups
^ • > 1,000,000
Air toxics
• £ 500,000-1,000,000
O 100,000 - 500,000
Fish consumption O 10,000 -100,000
^ n < 10,000
Severity Rating
   Once the results of the risk assessment have been characterized for each of the problem
areas, then decision makers will need to rank them based on the estimated human health
risks that they pose. However, a simple ranking based on quantitative risk estimates is not
possible for several reasons. First, ma"ny different metrics are used to describe human
health risks and-cannot be directly compared. Cancer and non-cancer risk metrics are par-
ticularly difficult to combine. Second, quantitative risk estimates are subject to consider-
able uncertainty, resulting in wide ranges of estimated risks. The overlap in these ranges
often precludes a simple ranking. Finally, there are many uncertainties in risk estimates
that cannot be quantified, but which warrant consideration in the ranking process.
September 1993

                                               2.2 Assessing Environmental Risks to Human Health
    Due to the difficulties in combining cancer and non-cancer effects in a single ranking,
  approaches for separate rankings are presented below. Suggestions for addressing non-
  quantitative factors,1 such as severity of effects and uncertainties in the ranking process, are
  also presented. This is typically done by systematically applying informed judgments to
  the ranking process. A technical advisor who is familiar with the uncertainties and non-
  quantitative factors of the analysis should take part in the process to ensure that such
  issues are communicated, correctly interpreted, and incorporated in trie rankings.

  Cancer Risk Ranking
    Ranking problem areas involves considering quantitative and non-quantitative factors,
  and determining their relative importance. As a result, the ranking process involves a great
  deal of judgment.                                           ,      ;
  Quantitative Factors
    •  Cancer Incidence— In most regional and state comparative risk projects, the estimat-
      ed number of annual excess cancer cases is the driving factor in the initial ranking of"'
      problem areas.                         j-                  '  ,
    •  Individual Risk—Differences in estimated individual lifetime risks are also impor-
      tant. In past projects, they have typically been considered after an initial ranking
      based on population risks.
    •  Sensitive Subfopidatiom—Environmental problems that pose relatively large risks to
      highly vulnerable or exposed populations deserve particular attention in the ranking
      process to ensure that decisions based on average risks do not underestimate
      inequitable risks to these groups.                                         '
 Non-quantitative Factors                 ,
    •  Seventy of Health Effect—Most comparative risk analyses have not distinguished
      between the severity of the different types of cancers. However, in situations where
      the cancers are not fatal, distinctions could be made and factored into the ranking
   •  Omissions in the Analysis—It may not be possible to analyze all asjjects of every prob-
      lem area, and it is likely that some problems will be more comprehensively analyzed
      than others. Therefore, it is important to Identify omissions in the analysis and assess
      how completely the results characterize the risks. If a particular problem area is
      thought to have substantial omissions, then this should be highlighted in the rank-
      ing process.                            i
   •  Quality of the Data and Analysis—Manyfactors can affect the quality of the data and
     the analysis and warrant consideration in the final ranking. The quality of toxicity
     and exposure data varies tremendously. For instance, the quality of medical or regu-
     latory case-study data, ambient- or biological-monitoring data, animal-testing data,
     and epidemiological data ate quite distinct from one another.
September 1993                                                              2.2-25

A Guidebook U> Comparing Risla and Setting Environmental Priorities
   •  Uncertainty—Omissions in the analysis and data-quality issues are components of
     uncertainty. In addition to these uncertainties, quantitative estimates of uncertainty
     related to estimated exposure concentrations and populations at risk should be fac-
     tored into the ranking process. If such estimates cannot be made, then the expected
     direction of the potential bias should at least be communicated to decision makers.
Combining Quantitative and Non-quantitative Factors
   There is a spectrum of possible approaches to combine the quantitative and non-quan-
titative factors of cancer risks, ranging from purely judgmental to rigorously quantitative,
in order to arrive at an integrated risk ranking. The following discussion presents three
options—one at cither end of the spectrum and an intermediate approach that imposes
some quantitative structure on the ranking process.
   At the judgmental end of the spectrum, one option is to examine the available informa-
tion—both quantitative risk estimates and non-quantitative factors—to arrive at a ranking
through a consensus-building process among work-group members. While simplistic in
concept, the effectiveness of this approach should not be underestimated. Developing the
cancer risk ranking requires simultaneous consideration of many pieces of information,
and this type of process  may provide the flexibility needed.
   The purely judgmental approach may not, however, provide die  structure necessary to
effectively and objectively rank the problem areas. The work group  may prefer ah interme-
diate approach that introduces moire organization and objectivity to the ranking process.
One way to achieve this structure is to first group the problem areas based on ranges of
cancer incidence, such as those described in Table 2.2.7.
               Table 2.2.7:
   Cancer-Risk Ranking Groupings
                                              Alternative groupings can be made
                                            based on a combination of population
                                            and individual risks or on "natural"
                                            breaks in the data. The groupings can
                                            then be adjusted based on considerations
                                            of other factors, such as the size of sensi-
                                            tive subpopulations, uncertainties in the
                                            analyses, and individual cancer risks (if
                                            not incorporated as a factor in the initial
                                            grouping). For example, if abandoned
                                            hazardous waste sites fall into Group 4 of
                                            the scheme presented in Table 2.2.7
                                            because the expected number of annual
cancer deaths is less dian 10, the work group may choose to elevate the problem area
because the estimated individual cancer risk is high relative to other problem areas and
because uncertainties in the exposure assessment indicate that more people are likely to be
exposed in the future.
   While this type of grouping process may serve as an intermediate step to establishing an
ordinal ranking, the work group may choose to forego a ranking and characterize the rela-
tive cancer risks posed by problem areas simply in terms of the groups. The problem areas
Expected Annual
Cancer Deaths
> 1,000
100 - t,000
                                                                   September 1993

                                              2.2 Assessing Environmental Risks to Human Health
 that will be most problematic will be those with quantitative risk estimates that extend
 into more than one group. In particular, the work group will need to discuss those areas
 that straddle group boundaries.              '
    More quantitative approaches to establishing cancer risk rankings IK also possible.
 Such approaches are characterized by a more rigorous integration of quantitative and non-
 quantitative risk information. One approach would be to translate the different risk met-
 rics and non-quantitative information into a consistent numerical form using a scoring
 system that has built-in weights representing the importance of different factors in ranking
 problem areas. The scores for the different factors could then be added to obtain, problem
 area scores that could be the basis for a rank ordering of problem areas. Computer pro-
 grams, such as the Analytic Hierarchy Process, are available to aid this type of ranking
 process. These types of ranking tools are discussed in Section 2.1.

 Non-cancer Risk Ranking
    Establishing a ranking of problem areas according to non-cancer risks also involves con-
 sidering quantitative and non-quantitative factors and determining their relative impor-
 tance. Ranking non-cancer risks is somewhat more complicated than I'anking cancer risks
 because of the diversity of non-cancer health effects and the difficulty in  estimating the
 potential number of cases. As a result, the ranking process involves a great deal of judg-
 ment in combining information on different factors..In past comparative risk studies,
 severity of health effects, dose/RfD ratio, and number of people exposed have been the
 primary factors on which the initial non-cancer ranking was based,   i
 Quantitative Factors                        i
   • Magnitude of RfD Exceeetance—The magnitude of the RfD exceedance is typically
     used to characterize the risks associated with non-carcinogens and is expressed as the
     ratio of the dose to the RfD (IER).  This is an important factor iri ranking problem
     areas for non-carcinogenic risks because the greater the dose/RfD, the greater the
     probability of experiencing an adverse health effect.
   • Number of People Exposed—The number of people exposed to non-carcinogens at
     concentrations exceeding the RfDs represents the population at risk of developing the
     associated health effect. Because this factor is typically used to indicate the potential'
     population risk, it is critical in establishing rankings of non-carcinogenic risks.
   • Sensitive Subpopulations—Problem areas posing risks to highly susceptible populations
     deserve particular attention in the ranking process to ensure that decisions based on
     general population exposures do not overshadow risks to specific groups as well.
Non-quantitative Factors    ~              i
   • Severity of Health Effects—Tint severity of health effects  is particularly important in
     ranking problem areas according to their non-cancer risks, since non-cancer health
     effects vary widely in type and severity with some producing lethal effects and others
     more subtle physiological effects.         I
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
   •  Omissions in the Analysis—IT. may not be possible to analyze all aspects of every prob-
     lem area, and it is likely that some will be more comprehensively analyzed than cith-
     ers. As a result, it is important to identify omissions in the analysis and assess' the
     extent to which the results characterize the whole problem area.
   •  Quality of the Data and Analysis—Many factors can affect the quality of the data and
     the analysis, and warrant consideration in the final ranking. The quality of toxicity
     and exposure data varies tremendously. For instance, the quality of medical or regu-
     latory case-study data, ambient- or biological-monitoring data, animal-testing data,
     and epidemiological data are quite distinct from one another.
   •   Uncertainty—Omissions in' the analysis and data quality issues are components of
     uncertainty. In addition to these uncertainties, quantitative estimates of uncertainty
     related to estimated exposure concentrations and populations at risk should be fac-
     tored into the ranking process. If such estimates cannot be made, then the expected
     direction of the potential bias should at least be communicated to decision makers.
 Combining Quantitative and Non-quantitative Factors
   The general options for developing a final non-cancer risjc ranking are similar to those
 discussed for cancer risk ranking in that they can be seen as existing along a spectrum that
 ranges from purely judgmental to  rigorously quantitative. The following discussion presents
 the three options identified for cancer and their application to non-cancer risk ranking.
   The option at the judgmental end of the spectrum is to examine the available informa-
 rion—quantitative estimates of potency and populations exposed, and non-quantitative
 factors—and arrive at a ranking through a consensus-building process among work-grouf)
 members. This approach may provide the level of flexibility that is needed. However, it
 may not provide the structure necessary to effectively and objectively rank problem areas.
 The work group may prefer an intermediate approach that introduces more organization
 and objectivity to the ranking process.
   One way to achieve this structure is to first group the problem areas based on ranges of
 the number of people exposed to  non-carcinogens at concentrations above their reference
 doses. Alternatively, groupings can be made based on natural breaks in the data or on a
 combination of population at risk, dose/RfD ratio, and severity of health effect. Separate
 groupings could be made for each of these factors and then combined into one overall
 grouping. The groupings could then be adjusted based on consideration of other non-
 quantitative factors, such as uncertainty or the quality of the underlying data. The prob-
 lem areas that will be most difficult to place in one grouping or another will be those that
 overlap into the range of an adjacent grouping. Given the uncertainties surrounding esti-
 mates of risk for various problem'areas, overlap among them is quite likely. However,
 despite this overlap, there should be large enough distinctions among groupings that those
 ranking them will be comfortable with the ranking results.         -
   More quantitative approaches  to establishing non-cancer risk rankings are also possible.
 Such approaches are characterized'by a more rigorous integration of quantitative and non-
 quantitative risk information, and have been used for past comparative risk studies. One

 2 2-28                                                              September 1993

                                               2.2 Assessing Environmental Risks to Human Health
  approach was used in Unfinished Business (EPA 1987) and has been used in many of the
  regional comparative risk studies. This approach involves the use of a scoring system (sec
  Table 2.2.8) that translates information on population exposed, dbse/RfD ratio, and sever-
  ity of health effect into a consistent numerical form. This system uses a four-point scale
  for all three factors, in essence giving them equal weight in the overall score. Other
  approaches might weigh factors differently, depending on the work group's judgment of
  the relative importance of the different factors.!

      Non-cancer  Risk Ranking Groupings
                                                    In a practical sense, each pollutant
                                                  within a problem area would be
                                                  scored, and die result for each pollu-
                                                  tant would be consolidated for the
                                                  problem area score. There are several
                                                  approaches for doing diis. One
                                                  approach would be to select the
                                                  chemical with die most severe health
                                                  effect and use it to represent the
                                                  problem area. In this case, the aggre-
                                                  gate score for the chemical with die
                                                  most severe effect would be die aggre-
                                                  gate score for the entire problem area.
                                                  Alternatively, die work group could
                                                  use.the pollutant with die highest
                                                 aggregate score to represent the prob-
                                                 lem area. If either of these approaches
                                                 is used, some problem areas are likely
                                                 to be better represented than others,
                                                 and this will need to be factored into
                                                 an evaluation of uncertainty. A third
                                                 alternative is to calculate an overall
                                                 score that incorporates the scores for
                                                 all pollutants analyzed by either aver-
                                                 aging or adding the scores for indi-
                                                 vidual pollutants. The problem with
                                                 these approaches is that the results are
                                                 largely dependent on the number of
pollutants analyzed. Adding scores for different pollutants may underestimate the relative
risks for some problem areas for which only a few substances were analyzed, and averaging
scores may underestimate relative risks for problem areas that have one dominant pollu-
tant but for which many less risky ones were also analyzed.      - •    i
2 .
Individual Exposure
< 1(3
10 - 100
> 1,000
< 1,000
> 10,000,000
Endpoint Severity
September 1993

A Guidebook to Comparing Risks and Setting Enviromnenud Priorities
   Regardless of how the scores are aggregated to obtain a total score for non-cancer health
effects associated with each problem area, this approach allows problem areas to be ranked
according to their scores. An uncertainty score could also be incorporated into this system
that would adjust the aggregate score upward if there was a high degree of uncertainty
associated with the assessment of the problem area. For example, scores of one, two, or
three could be added for low, medium, and high levels of uncertainty. The factors to con-
sider in evaluating the degree of uncertainty associated with the assessments include the
quality and quantity of data used (e.g.; animal toxicity data,,epidemic! ogical data, ambi-
ent- and  biological-monitoring data, and medical or regulatory case-study data), the num-
ber of chemicals analyzed, and the degree of extrapolation performed. Uncertainties in the
more quantitative factors could be considered in assigning scores for potency, exposure,
and severity.

   From  the standpoint of providing inputs to the risk management phase of the effort,
producing a combined health risk ranking incorporating cancer and non-cancer effects
can be useful. A combined health ranking is also more consistent with the outcomes of the
quality-of-life and ecological analyses and allows for more direct comparisons, of problem
areas for planning, budgeting, and resource allocation purposes. '
   The process for combining cancer and non-cancer health, effects can be non-quantitative
or semi-quantitative. A non-quantitative approach relies heavily on the judgment of the
work group to interpret the significance of the various quantitative and non-quantitative fac-
tors. The outcome of this process might be an ordinal ranking or the assignment of problem
areas to categories representing various levels of risk arrived at through group consensus.
   A useful tool to aid this process would be to array the information most critical to the
ranking decisions in a matrix that combines cancer and non-cancer effects. An example of
such a matrix is shown in Table 2.2.9 This table presents a partial representation for illustra-
tive purposes; a complete summary table would include risk estimates for all problem areas.
   The most important thing about this table is that it groups cancer and non-cancer
health effects into three separate categories of relative risk: catastrophic, serious, and
adverse.  Most displays of health effects separate cancer from non-cancer health effects.
This table presumes that the issue of greatest importance is the severity of the health effect
rather than distinguishing between cancer and non-cancer cases.
   This matrix combines information on the number of people at risk to cancer and non-
cancer effects of varying severity for three problem areas. This allows for direct and mean-
ingful comparison of the factors critical to ranking. The number of people at risk from
cancer is actually an estimate of the incidence of disease, whereas the estimates for non-
cancer health effects represents the number of people exposed to potentially harmful con-
ditions (i.e., with a dose/RfD ratio of greater than one). In cases where incidence data are
available for non-cancer effects, the metrics may be more comparable. Once the work
 2 2_30                                                  •           September 1993

                                              2.2 Assessing Environmental Risks to Human Health
 group establishes an initial ranking, other factors such as individual rislcs, the magnitude
 of RfD exceedances, and uncertainty, can be considered in adjusting the ranking.
                                    Table 2.2.9:
                Summary Matrix of Cancer and Non-cancer Effects
Problem Area
Air Toxics
Drinking Water
Hazardous Waste
Number of People at Risk From
Gancer and Non-cancer Health Effects
. 1.2*
• Adverse
, 10,000
Number of potential cancer cases are noted by an asterisk (*); sill other
numbers represent the estimated number of non-cancer health effects
with dose/RfD ratios > one. "
   Although this judgmental approach offers a great deal of flexibility, it may not provide
the structure necessary to objectively rank the combined human health risks of different
problem areas. The work group may prefer a more organized, semi-quantitative approach.
Table 2.2.10 illustrates how this could be accomplished, using the three categories of rela-
tive risk displayed in Table 2.2.10 (i.e.; catastrophic, serious, and adverse). It would seem
reasonable to assume that there would be a greater level of concern over catastrophic
health effects than either serious and adverse effects, and greater concent over serious
effects than adverse effects. Theoretically, different weights could be attached to the differ-
ent categories to reflect the different levels of concern with the more severe health effects.
   The table presents hypothetical cancer and non-cancer rankings for six problem areas
and an overall human health rating, which is simply the aggregation of rhe health effect
category rankings. In this example, no explicit weights have been attached to the different
categories of effect, although this could easily be done. If the work group wanted to place
more or less importance on the different categories, it could make adjustments by weight-
ing them accordingly.                        \
   The drawback of this type of approach is that it relies completely on the initial rankings
and does not reconsider the relevant factors in the context of a broader human health rank-
ing. An alternative semi-quantitative approach to combined rankings that explicitly incor-
porates consideration of these factors would be to develop a more elaborate scoring scheme,
such as a modification of that used in Unfinished Business (SPA. 1987) to rank non-cancer
effects  (see discussion of non-cancer risk ranking). The modifications could include incpr-
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
porating criteria for average individual cancer risk, population cancer risk, and severity of
cancer effect to establish respective potency, exposure, and severity scores for cancer effects.
Great care must be taken in developing such a scoring scheme to ensure that the judgments
implicit in the relative scores are consistent with the work group's understandings.
                                   Table 2.2.10
                   Combining Cancer and Non-cancer Effects
Problem Area
Air toxics
Drinking water
Indoor air
Surface water
Hazardous waste
   The options presented here for combining cancer and non-cancer risks into an overall
human health ranking are only examples of general approaches that can be considered.
Each approach involves some effort to develop and implement, but the effort is well worth
it since it is crucial that project participants and the general public understand the
approach and find it reasonable and reflective of their values. Factors that the work group
might want to consider in developing an appropriate approach include agreeing on the
objective of the effort, the quality and precision of the analytic results, the expertise of the
ranking group, and the time and resources available. It is important to consider these fac-
tors in the planning phases of the project so that data can be developed and presented in a
way that is consistent with and supports the approach used in  ranking problem areas.    >
September 1993

                                             2.2 Assessing Environmental Risks to Human Health
  Casarett, Louis J., and John Doull.  Casarett and Doull's Toxicology. Edited by John Doull,
  Curtis Klaassen, and Mary Ambdur. New York MacmUlan Publishing Co., Inc.  1980.
  Finkel, Adam M.  Confronting Uncertainty in Risk Management. Center for Risk
  Management, Resources for the Future. Washington, D.C. January 1990.
  National Academy of Sciences.  Risk Assessment in the Federal Government: Managing the
  Process. Washington, D.C.  1983!           |
                                         • l                    •            '
  U.S. Environmental Protection Agency (U.S. EPA).  Office of Health and. Environmental
 Assessment.  Environmental Criteria and Assessment Office. General Quantitative Risk
 Assessment Guidelines for Non-cancer Health Effects. Second External Review Draft.
 Cincinnati, OH. February 1991.            t
    ~-                        -              r
 U.S. EPA. Science Advisory Board., Report of the Human Health Subcommittee:  Relative
 Risk Reduction Project, Appendix B, Washington, D.C. September 1990.

 U.S. EPA. Ambient Paniculate Matter and Ozone BenefitAnalysis for Denver...Preparedby
 RCG/Hagler, Bailly,  Inc. Washington, D.C.  1988a.

 U.S. EPA.  Office of Research and Development. Environmental Criteria and Assessment
 Office. Integrated Risk Information System. Background Document 2: "EPA Approach for
 Assessing the Risks Associated with Chronic Exposures to Carcinogens." Cincinnati, OH.
 February 1988b.                           j              ,                        '-

 U.S. EPA.  Office of Policy, Planning and Evaluation. Office of Policy Analysis.
 Unfinished Business: A Comparative Assessment of Environmental Problems, Appendix II.
 Washington, D.C. February 1987.          '
      . -             '             "         I          -,          '
 U.S. EPA.  "Guidelines for Carcinogen Risk Assessment."  Federal Register, vol. 51, no.
 185 (9/24/86).  Washington, D.C.           j                      ,          •

 U.S. EPA.  Development  of Statistical Distributions or Ranges of Standard Factors Used in
 Exposure Assessments.  Prepared by GCA Corporation. Washington, D..C.  August 1985.

 U.S. EPA.  Office of Health and Environmental Assessment. Handbook for Performing
 Exposure Assessment. Washington, D.C. 1983.,                                -
September 1993


 Phase 1:Problem Formulation	.'.......                      x
      Task 1: Review the List of Problem Areas and Definitions......:...	 	....5
      Task 2: Partition the Study Area Into Geographic or Ecological Areas	6
         By Geographic Areas	'.	,	:	              --     g
         By Ecosystem Type,,	       ....            g
      Task3: Select Evaluative Criteria	...i.	                       JQ
      i  Areaoflmpact	;.	........              10
        Severity of Impact	'.....	            \\
        Reversibility of Impact	;....	„_                   jj
        Uncertainty	           12
        "Value" of Ecosystems	i.....	^	,;,             12

 Phase2:Analysis	„        •                  ia
      Task 1: IdentifyStressors	 J..	'.     .............         13
      Task2: Estimate Exposures/Co-dccurrenccL...	...,:....           14
      Task3: Characterize Ecological Effects	    i...........      17

 Phase3: Risk Characterization	|	<                -t-j
      Task 1: Summarize Each Problem Area Using Evaluative Criteria	18
      Task 2: Summarize the Risk to Each Ecosystem or Geographic Area	20
      Task 3: Aggregate Risks Across Ecosystems or Geographic Areas	20

Phase 4: Comparison andRanking.....	„..	J	       21
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
   2.3.1  Ecological Problem Areas, Stressors, and Sources .
   2.3.2  Hypothetical Pesticide Example   	
   2.3.3  Hypothetical Narrative Description for Pesticides.
   2.3.1  Four Phases of a.Comparative Ecological Risk Assessment	•••••3
   2.3.2  Portions of Two State Problem-Area Lists  	••••	--5
   2.3.3  Calculating Risk Using the EPA Region VI Cross-Cutting Approach ......:.....7
   2.3.4  Ecosystem Classification Schemes Used in Two State Projects.	:.	8
   2.3.5  Federal Approaches to Classifying Ecosystems  	9
   2.3.6  Narrative and Numeric Scales for Evaluative Criteria	20
   2.3.7  Summary Table of Ecological Risks Across All Problem Areas	21

END NOTE	•	;22
                                                                    September 1993

                                                   2.3 Comparing and. Assessing Ecological Risks
A         comparative ecological risk analysis is a process of identifying, analyzing, evaluat-
         ing, and ranking the effects of manmade "stressors" on ecological "receptors." A
         stressor is any chemical agent or physical activity that can harm an ecological
 receptor. An ecological receptor1 can be an individual of a single species, a population of
 species, a community of interacting species, or the functional or structural integrity of an
 entire ecosystem. Risk does not exist unless a stressor comes into contact or co-occurs with
 an ecological receptor.                    '  i                      !  .
   A comparative ecological risk analysis applies the principles of risk analysis to available
 data, supplemented by best professional judgment, to rank the relative risks of significant
 environmental "problem areas." Problem areas are evaluated and ranked in terms of a set
 of criteria that reflect the environmental values that society is most concerned about, such
 as the loss of biodiversity or whether the damage is temporary or irreversible.
   As presented in Exhibit 2.3.1, a comparative ecological risk analysis involves four
 phases. Each of these phases is discussed in summary below and  in detail further on.
 Because  the process is iterative, it may be necessary and advisable to revisit some initial
 decisions in later phases to ensure that they are still appropriate.

                                    Exhibit 13.1:
               Four Phases of a Comparative Ecological Risk Assessment
                           I   Problem Formulation  |;
                              Risk Characterization
                             Comparison & Ranking {
     Phase 1:
Problem Formulation. The fiirst phase of a comparative ecological risk
analysis is a systematic planning process that includes reviewing the list
of environmental problem aireas, partitioning the project area (e.g., a
state) into a number of different ecological or geographic areas, and
selecting a set of criteria to evaluate ecological risks and rank the prob-
lem areas. In addition, a preliminary examination of data needs and
constraints m'ay be necessary.
September 1993

A GtadtbooJt to Comparing Risks and Setting Environmental Priorities
     Phase 2:     Analysis. In the second phase of an analysis, the goal is to establish a
                  causal link between the problem areas and their ecological effects.
                  Therefore, each problem area is broken down into a set of the most
                  important stressors. The fate and transport of each stressor is then
                  tracked through the environment to determine likely ecological effects.
                  This requires knowledge about the toxicity of chemical stressors and
                  the presence of physical stressbrs, the exposure or co-occurrence of eco-
                  logical"receptors to stressors, and the response of ecological receptors to
                  stressors. Where data are lacking or inadequate, professional judgment
                  and consensus building are needed to supplement gaps in data, sources
                  of uncertainty, and a lack of knowledge about complex ecological •  -
                  processes and interactions.                    ,
     Phase 3:     Risk Characterization. The third phase of a comparative ecological risk
                  analysis involves using the analyses to characterize the risks posed to
                  the environment by different problem areas. Risks are characterized in
                  terms of a set of common evaluative criteria. These criteria may
                  include factors such as the area, severity, and reversibility of impacts.
                  Values or weights can be assigned to each criterion using numerical
                  scales or short narrative descriptors. Risk characterization also includes
                  a summary of the assumptions and scientific uncertainties embedded
                  in the analysis and their anticipated implications.
     Phase 4:     Comparison and Ranking. The final phase of a comparative ecological
                  risk analysis involves comparing the ecological risks posed by different
                  problem areas and ranking them into several broad categories. This is
                  accomplished by considering ecological risks for each problem area in
                  terms of the evaluative criteria. Professional judgment supplements
                  gaps in data or knowledge, but the level of precision required is only as
                  great as .that needed to make rough relative comparisons, rather than
                  absolute estimates, of risk. Problem areas are then ranked using a mix-
                  ture of available data and best professional judgment through a con-
                  sensus-building process.

   The problem formulation phase of a comparative ecological risk analysis consists of a
systematic planning process to establish the goals, breadth, and focus of the analysis.
Three major tasks are performed in this phase. First, the problem area list is reviewed to
identify problem areas that do  not pose any ecological risks, such as indoor radon. These
problems do not need to be analyzed from an ecological perspective. Second, the area of
the analysis, such as a state or a region of the country, should be partitioned into different
ecological or geographic areas.  Third, the criteria used to evaluate and rank problem areas
should be selected and defined.
2.34                                                               September 1993

                                                     2.3 Comparing and Assessing Ecologitol Risks
  Task 1: Review the List of Problem Areas and Definitions
    Most problem areas will generally be applicable to all three analytical components (i.e.,
 the human health, ecological, and quality-of-life analyses) of a comparative'risk project.  -
 However, a few problem areas may not have an ecological component and do not need to
 be analyzed by the ecological work group. For example, radon does noi; pose any ecological
 risks, but does pose both human health and quality-of-life risks. Conversely, other problems
 that cause ecological impacts may not be on an initial list of problem areas and should be
 added. The most prominent example of this has involved the physical idteration and degra-
 dation of terrestrial and aquatic habitats, such as urban sprawl or filling wetlands.
   All problem areas should be clearly defined in terms of which sources, stressors, and
 exposure pathways are included and excluded in the definitions. Since they will be conduct-
 ing the analysis, the ecological work group members should be consulted extensively about
 definitional issues or any other issues affecting the ecological analysis. Work group mem-
 bers may want to review Section 2.1. on selection criteria for developing a problem-area list.
   Colorado conducted a comparative risk project in 1988-90 using a problem-area list
 and analytic design that reflects its own unique natural environment and public concerns
 (Colorado  1990). The 31 problem areas in Colorado's list were separated into four cate-  '
 gories: air, land, water, and natural resources. This list was intentionally constructed with
 some overlap between problem areas, and the project acknowledged the possibility  of
 some double counting of risks.                                           .
   A noteworthy aspect of Colorado's project is the natural resources problem-area list and
 analytic approach. Rather than using the effects of pollution as the basis for analyzing and
 ranking problem areas, the natural resources work group focused on the ecological value,
 vulnerability, and economic value of different ecosystems. The 10 problem areas in the
 natural resources category are listed in Exhibit 2.3.2.
                                    Exhibit 2.3,2:                     I
                         Portions of Two State Problem-Area Lists         :
           Colorado's Natural Resources List
            • Wetlands and Riparian Areas
            • Threatened and Endangered
             Species Habitats
            • Resources of Special Interest
            • Critical Wildlife Habitats
            • Aquatic Habitats
            • Recreation Opportunities
            • Urban Environments
            • Plains Land
            •Forests             '
            • Open Space
  Unique Michigan Problem Areas
• Absence of Land-Use Planning;
• Biodiversity/Habitat Modification

• Lack of Environmental Awareness
• Contaminated Surface-Water Sediments
• Electromagnetic Field Effects i
• Energy Production and Consumption
• Alteration of Surface-Water and
 Ground-Water Hydrology     >
September 1993

 A Guidebook to Comparing Risks and Setting Environmental Priorities
    The Michigan project developed a list of 23 problem areas (Michigan 1992). Some of
 the more unusual and original problem areas are also below in Exhibit 2.3.2. Unlike
 Colorado, each of the three working committees (an agency committee, a citizens' com-
 mittee, and a scientists' committee) evaluated and ranked all 23 problem areas.

 Task 2: Partition the Study Area Into  Geographic or Ecological Areas
    The study area (e.g., a state or region of the country) of a comparative risk project
 should be partitioned into a manageable number of ecosystem types or geographic areas.
 Different ecosystems vary in their vulnerability and resilience to stressors, while the same
 type of ecosystem in a different geographic location may be more at risk due to a very dif-
 ferent stress regime. If the study area is partitioned according to ecosystem type, then dif-
 ferent ecosystems, such as wetlands or pine forests, would be analyzed regardless of their
 location throughout the state. Conversely, the study'area can be partitioned into separate
 and distinct geographic areas, such  as particular rivers, valleys, or mountain  ranges.
    Partitioning the study area'into a number of ecological  or geographic areas  also makes it
 possible to evaluate ecological risks  in a cross-cutting fashion. First, the risks due to a par-
 ticular environmental problem can  bts summed across all ecological or geographic areas .in
 the study area to determine the total risk posed by that problem area. Not only will man-
 agers know which problems pose the greatest risks  to the environment, they will also know
 where the most severe risks occur, and can target response activities in those  areas.
 Conversely, the total risk posed by all the problem  areas within a given ecological or geo-
 graphic area can be summed up to determine which ecosystems or geographic areas are at
 greatest risk overall. This information allows environmental managers to integrate cross-
 media response activjties that address multiplevthreats simultaneously in those ecosystems
 at greatest risk.                                                       .
   How the project area is partitioned is important because it affects many aspects of the
 analysis, such as the number of analyses that are performed, the amount and type of data
 that must be collected and analyzed, and the degree of resolution and geographic targeting
 that can be achieved as a result of conducting the analysis. Therefore, selecting the appro-
 priate ecological approach depends oh the purpose for conducting the analysis,~the avail-
 ability and quality of data, the size and natural variability of the project area, and  the ease
 and effectiveness of communicating the analytic approach  and results to senior managers,
 political leaders, and the public.
 By Geographic Areas
   Several comparative risk projects  have partitioned their state or region into specific geo-
 graphic areas, such as particular bays, river valleys, grasslands, or mountain ranges. This
 approach is used for a number of reasons. First, since the damages caused by stressors are
 spatial in nature, it makes sense to analyze the likelihood of adverse effects geographically,
 rather than by the ecological type of the receptor. For example, mixed conifer forests in
 southern California are likely to be exposed to much higher levels of air pollution than the
same type of forests in northern California. Attempting to describe the combined damages
 to all mixed conifer forests in California as a single value is likely to be unsatisfactory.

2.3-6                                                               September 1993

                                                   2.3 Comparing ami Auesang Ecological Risks
   Another important advantage of dividing the study area into specific geographic areas is
that it may be easier to communicate with and build support among die general public
about the results of a comparative risk project. For instance, it may be more difficult to
communicate to the public the risks of pesticide use in bottomland hardwood forests or
tall grass prairies than to rally public support around the risks posed to a specific area (e,g.,
the "Save the Bay" campaign in the Chesapeake Bay area). Exhibit 2.3.3 illustrates the
cross-cutting approach mentioned above that v/as used in the EPA Region VI comparative
risk project in 1990 (EPA 1990a).         .   ( .._-''           _   ,       :

                                     Exhibit 23.3:                  !
               Calculating Risk Using the EPA Region VI Cross-Cutting Approach
EPA Region 6 "
» ^
Problem Areas
Non-point Discharges
10 Surface Waten
Physical Degradation of
Water and Wetlands
Municipal (POTW) Dis-
charges to Surface Wales
Active Hazardous
Waste Sites (RCRA)
Abandoned Hazardous
Wane Sites (Superfund)
Application of
Ozone and Carbon
Physical Degradation of
Terrestrial Habiuts
Total Rfcki by

" >




• • '

   Ecoregions are geographic areas of relative ecological homogeneity in terms of the rela-
tionships between organisms and their environments. They are distinguished by land use,
topography, potential natural vegetation, and soil type. EPA Region VI chose to use ecore-
gions, as opposed to ecosystems, as the unit of analysis for several reasons. First, all 24
ecoregions located within the five-state area of Region VI have been electronically mapped
or "digitized." In fact, all 76 ecoregions located, within the 48 U.S. continental states have
been digitized. Second, by digitizing ecoregions into a geographic information system
(GIS), it is possible to simultaneously analyze multiple layers of other digitized data sets
and graphically display them ontan ecoregion-by-ecoregion basis. For instance, Region VI
was able to analyze and display the spatial relationship of ground-water resources to
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
underground storage tanks, roads, and waste sites. Finally, the 24 ecoregions provided a
level of resolution that was sufficient, yet manageable for the regions purposes.
   However, not every comparative ecological risk analysis should evaluate' risks at the
ecoregion level. For instance, in states like Georgia or Nevada, where one ecoregion covers
over 75 percent of the entire land area, this approach may not provide an adequate level of
resolution. In addition, GIS technology is very resource-intensive and expensive and may
not be critical or necessary to the success of every project.
By Ecosystem Type                                            . ,
   Many state and EPA comparative risk projects to date have classified ecological areas by
type. The distinction among ecological types can range from very simple schemes, as
demonstrated by the Vermont comparative risk project, to more complex approaches,
such as that used in Hawaii's project, which specified over two dozen ecosystem types
(Vermont 1991; Hawaii 1992). These state examples are shown in Exhibit 2.3.4.
                                   Exhibit 2.3.4:
             Ecosystem Classification Schemes Used in Two State Projects
              • Terrestrial ecosystems
              • Aquatic ecosystems
              • Wetlands
              • Rare ecosystems
' Reefs (both barrier and fringing)
• Coastal waters, bays, and beaches
> Wetlands, streams, and estuaries
> Lowland tropical moist forests
> Lowland and montane dry forests
> Lava tubes and caves
> Grasslands
           \      .
> Arid lands
> Alpine deserts
   In Vermont, the most important stressors associated with each problem area were ana-
 lyzed in terms of their ecological effects on four types of ecosystems. Ecological effects' ,
 were measured in terms of the size of the area affected, disruptions to the function and
 structure of whole natural communities rather than individual species, and recovery time
 for the ecosystem to return to a natural state once the stressor was removed.
   The Hawaii Environmental Risk Reduction project originally partitioned the Hawaiian
 islands (excluding urban and agricultural areas) into 29 different ecosystem types. To
 make the analysis more manageable, this number was later lowered to 18 by combining
 similar ecosystem types. Furthermore, every "occurrence" of each ecosystem type was indi-
 vidually assessed because of the different stress regimes experienced by the same ecosystem
 type in different locations on the islands. For instance, the risks to fringing reefs on oppo-
                             September 1993

                                                   • 2.3 Comparing and Aliening Ecological Riski
 site sides of an island or on different islands can vary tremendously because of their expo-
 sure to different kinds and magnitudes of stress. Project participants believe that these arc
 important distinctions that justify the higher costs and effort required to collect the infor-
• mation because environmental managers can iphcn target activities to iaddress threats to
 specific ecosystems at the greatest risk.       >

   Exhibit 2.3.5 below depicts two different approaches used at the federal level to parti-
 tion the natural landscape according to ecosystem type. On the left is the approach used
 by the ecological work group of EPA's Unfinished Business project (EPA 1987); the
 approach on the right is the approach used by EPAs Environmental Monitoring and
 Analysis Program (EMAP).                 j

                                  Exhibit 23.5:
                 Federal Approaches to Classifying Ecosystems
      Ecosystems Defined by EPA's
   National Comparative Risk Project
                                        Resource Classes Defined by EPA's
                                                   EMAP Office
Freshwater Ecosystems
  Buffered lakes
  Unbuffered lakes
  Buffered streams
..  Unbuffered streams

Marine and Estuarine Ecosystems
  Coastal ecosystems
  Open ocean ecosystems

Wetland Ecosystems
  Buffered freshwater isolated wetlands
  Unbuffered freshwater isolated wetlands
  Freshwater flowing wetlands
  Saltwater wetlands

Terrestrial Ecosystems
  Coniferous forests        ••'•.-.
  Deciduous forests
  Grassland ecosystems
  Desert and semiarid ecosystems
  Alpine and tundra ecosystems
                                           Inland Surface Waters

                                           Near Coastal Waters
                                             Large, continuously distributed estuaries
                                             Large, continuously distributed tidal rivers
                                             Small, discretely distributed estuaries, bays,
                                             inlets, tidal creeks, and rivers

                                           Wetlands             ;

                                             22 forest types

                                             Grasslands       Savanna
                                             Chaparral        Shniblands
                                             Woodlands       Tundra
                                             Riparian  ,           j

                                           Agroecosystems   '   .\  •
                                             Field, vegetable, and forage crops
                                             Fruit and nut crops
                                             Managed pasture and non-confined
                                             animal operations
                                             Confined animal-feeding; operations   '•
September 1993

 A Guidebook to Comparing Risks and Setting Environmental Priorities
 Task 3: Select Evaluative Criteria                     .
   The information upon which ranking decisions are based can simultaneously be over-
whelming and inadequate. This can lead to a feeling of comparing apples and oranges.
However, a set of evaluative criteria can "translate" the risk characterizations for different
problem areas into a common language so that decision makers can compare and rank
them. Evaluative criteria also help in limiting the scope of data collection and analysis
efforts to information that is pertinent to the types of decisions  that will ultimately need
to be made.                                              ,
   To be useful in evaluating and comparing problem areas, criteria should:
   •  Be explicitly defined to be mutually exclusive. This prevents double counting certain.
      aspects of the impacts, such as the "severity" and "reversibility" of effects.
   •  Be common to all problem areas, which vary considerably, to facilitate consistent
      analysis across problem areas.
   •  Vary from one problem area to the next, even though they are common to all prob-
      lem areas, such as the area or severity of impact.
   •  Be measurable and, if possible, quantifiable. Any subjective judgments used to evalu-
      ate problem areas should be peer reviewed and documented for the benefit of any
      future reference or outside review.        *         .   .
   Classifying or "scoring" ecological effects for most evaluative  criteria often involves
using some professional judgment. Thus, the risk ranking will reflect the experience and ,
knowledge of the individuals working on the project.  Depending upon the resources avail-
able and the objectives of the project, the ecological analysis can range from simple non-
quantitative statements based upon the knowledge of the project participants to more
data-intensive approaches that quantify multiple aspects of the effects. For example, trend
analyses might simply involve the work group agreeing that the  impacts of a given prob-
lem area are increasing, remaining stable, or decreasing. It may also use a more quantita-
tive approach of modeling various economic, technological, and demographic trends.
However, the ecological analysis does not have to be a labor- and data-intensive undertak-
ing. In fact, the analysis should be no more detailed and resource-intensive than is neces-
sary to rank problem areas relative to one another and identify the ecosystems or geo-
graphic areas at greatest risk.
   During the past several years, a number of evaluative criteria have consistently been
used in regional and state comparative ecological risk projects. Some of these criteria are
described below.
Area of Impact
   The area of potential impact in comparative risk projects is based on the extent of the
effect, rather than the area of overlap between stressors and ecological receptors. This is
because the effects of a given stressor, on a receptor can extend far beyond the immediate
area of their co-occurrence. For instance, the effects of eliminating a critical habitat for
2.3-10                                .                              September 1993

                                                    2.3 Comparing and Assessing Ecological Risks
 migrating waterfowl or anadromous fish can extend.far beyond that area to the entire
 migratory flyway or aquatic life-cycle habitat of that species.
    The first step, which can be difficult, is to estimate the proportion of impacted area
 within each ecosystem or geographic area. Then it is a simple matter to sum these esti-
 mates across ecosystems or geographic areas to determine the entire area affected within
 the study area. This step differs among problem areas. For example, ki the case of air pol-
 lutants, the entire ecosystem may be assumed 1:0 be affected. However, the most severe
 impacts may be limited to urban areas, with less severe effects experienced in rural parts of
 the ecosystem. The area of impact for waste sites has been estimated by using an average
 estimate for each site and then multiplying that by the number of sites within the ecosys-
 tem. Information on the number of stream miles or coastline affected or the number and
 location of violations of water permits may be used to estimate the area of impact in
 aquatic environments.                       !                               ,
 Severity of Impact                                     -    .            ,
    Effects from both physical  and chemical stnssors can be analyzed and evaluated in
 terms of their "severity" on ecosystems or geological areas. This is a function of the toxicity
 of a chemical stressor, the exposure to the stressor, and the vulnerability of the ecosystem
 or geographic area. For physical stressors,  the degree or kind of impact is estimated and
 characterized, rather than the stressor's toxicity. For instance, the building of a road
 through a migration corridor  is likely to cause habitat loss and fragmentation and may dis-
 rupt reproductive activities.                  I
   Defining terms carefully, and clearly is probably most critical for the severity criterion.
 It is important to keep criterion mutually exclusive in order to avoid double-counting
 effects under two separate criteria. By its very nature, the concept of severity tends to
 encompass other criteria, such as vulnerability or reversibility. For instiince, when evaluat-
 ing the severity of a chemical stressor on an ecosystem, it is difficult to separate the toxici-
 ty of the stressor from the ecosystems vulnerability to it. Similarly, the severity of an effect
 can easily be stated in terms of its reversibility. For example,  if a problem area is ranked
 high in terms of severity because it causes  "permanent or irreversible damage to the ecosys-
 tem," then double counting of effects is occurring if there is a separate "reversibility" crite-
 rion. It is preferable to retain the distinction of reversibility as a separate criterion from
 severity in order to be able to distinguish one stressor that causes severe and long-term
 effects from another stressor that may be equally severe but has short-lived effects.
 Reversibility of Impact                     j
   The reversibility criterion is used to account for the resilience of different ecosystems
 and the persistence of physical or chemical stressors. It is an estimate of the time required
 for an ecosystem to regain its normal structural and functional properties after the stress
 has ceased. Reversibility can be measured in terms of very short time periods (e.g., days,
weeks, or months) to much longer time period;; (e.g., years, decades, or irreversible
 effects). Whatever time periods are used should, be sufficiently broad to indicate very large
 differences, in the reversibility of impacts. For instance, if a five-point interval scale is used,
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
then a value of one might indicate the ecosystem's return to normalcy in less than one
year, whereas a score of five might indicate an irreversible effect. Intermediate scores would
be assigned to periods ranging from several years to decades to centuries.
   There is an important distinction to keep in mind between the reversibility of impacts
and the vulnerability of different ecosystems, which is sometimes confusing. While the
reversibility of an impact is clearly a component of an ecosystem's vulnerability, the two
terms can be distinguished in terms of the timing of the stress. The vulnerability of an
ecosystem to stress indicates the ecosystem's response to a stressor, whereas .the reversibility
of an effect indicates the ecosystems ability to bounce back from a stress following the ces-
sation of that stress. These are simply different ways of analyzing the same phenomenon.
However, it is useful to maintain this distinction.
Uncertainty                     •
   The degree of uncertainty associated with each of the evaluative criteria should be
noted to decision makers. The uncertainty surrounding estimates may be attributed to a
number of sources: lack of data and knowledge about stress- response relationships,  infer-
ential judgments of community- or ecosystem-level effects based on data at lower biologi-
cal levels of organization, extrapolating information from a small sample size or another
section of the country where conditions might differ, or interpolating information from
regional or national studies.                        ,              •    -     t '
   Uncertainty can also be used as a qualifier rather than as an explicit evaluative criterion.
Options include using uncertainty to increase the risk estimate (i.e., higher uncertainty
would result in a higher risk estimate), to decrease the risk estimate (i.e., higher uncertain-
ty would result in a lower risk estimate), or as a communication tool (i.e., the level  of
uncertainty would not affect the risk estimate but would be communicated to decision
makers). Uncertainty can be used as an indication of the "cost" of being wrong; in this
case, uncertainty surrounding the catastrophic potential of a problem area (e.g., global
warming) would raise the risk estimate. From a practical standpoint, high uncertainty can
be used to identify areas where new research and data collection efforts  are particularly
important versus other problem areas where uncertainty is minimal and response activities
can be implemented immediately. Moreover, sensitivity analyses can be very valuable in
bounding uncertainty estimates.
"Val ue" of Ecosystems
   This criterion is used to represent the different values attached to different ecosystems
due to their scarcity, ecological value, uniqueness, human valuation, or any number of •
other factors creating value. The advantage of this criterion is that it can highlight the
importance of certain ecosystems in order to focus attention on the problem areas affect-
ing them. Conversely, not including an ecosystem's value or importance in a ranking
process  implies that all ecosystems arc equally valuable.
   To illustrate this point a project's participants may decide that the ranking of a prob-
lem area, such as outdoor air pollution affecting an important national park, is too low
based solely upon the area and severity of impact and its  reversibility. It may be that due to
2.3-12                                     .                         September 1993

                                                    2.3 Comparing and Assessing Ecological Risks
other "values" the park provides to man and nature, the problem area should be ranked
higher. Or decision makers might believe that ranking a 10 percent loss ,of the few remain-'
ing wetlands in a state should be higher than a 10 percent loss of rang;eland acreage,
because of the scarcity of wetlands and the critical habitat it provides, to a complex com-
munity of animal and plant species, even though the area, severity, and reversibility of
impact are roughly equal to the rangeland loss, A value criterion can provide a way to
reflect this difference in the relative value of ecosystems.
   Only a small minority of projects to date have added a "value" criterion to .their evalua-
tive criteria. Some project participants believe that the value of ecological areas to people,
in terms of recreational, spiritual, or aesthetic benefits, should be addressed  in the quality-
of-life analysis of a comparative risk project. Qther participants think that all ecosystems
are equally important and valuable and that these evaluations are too subjective to be sci- >
en tificaliy credible. The decision to include value as an evaluative criterion is a choice that
must be made on a project-by-project basis.

PHASE 2: ANALYSIS                    ;  •
   The analysis phase of a comparative ecological risk analysis consists of three main
tasks: identifying the physical or chemical stressors associated with each problem area,   •
estimating the exposure or co-occurrence of these stressprs with ecological receptors of
concern, and characterizing the resulting ecological effects. Ideally, it would be possible to
establish a causal relationship between stressors and their ecological effects. However, this
is rarely achieved because of gaps in knowledge or data, uncertainties:, or information that
must be interpolated from larger studies (e.g., natipnai studies) or extrapolated from
smaller studies (e.g., site-specific studies). Often, the ecological effects of interest in a
comparative ecological risk analysis are at higher levels of biological organization, such as
the community and  ecosystem  levels, than the available information. These effects are
often based on studies at lower levels of biological organization, such as field or laborato-
ry studies of a single species population.  This introduces uncertainty and requires apply-
ing professional judgment carefully.          •    '  ._                                .

Task It Identify Stressors
  A "stressor" is defined as any physical or chemical agent that can induce an adverse eco-
logical effect/Examples of physical stressors include draining wetlands or channeling
rivers. The ecological effects they might cause include the loss pf natural resources, filter-
ing and detoxification functions, and wildlife habitat. Chemical stressors include organic
and inorganic substances such as lead, asbestos, heavy metals, and volatile organic com-
pounds. They can affect any level of biological organization from an. individual of a
species to an entire ecosystem or landscape.
   Stressors should be identified for every problem area analyzed. For jiome problem areas,
the stressors are obvious, such as^environmemal lead and asbestos. In these cases, the risk
associated with each problem area is determined by a single stressor. However, for many
problem areas with multiple stressors it is not practical to conduct an ecological analysis
September 1993

 A Guidebook to Comparing Risks and Setting Environmental Priorities
 for each one. In these cases, it is necessary to select a manageable number of the most
 important stressors and assess their cumulative impact. There are also problem areas where
 the secondary stressors are very important to analyze, such as stratospheric ozone deple-
 tion caused by chlorofluorocarbons  (CFCs) which can result in increased exposure to     i
 ultraviolet radiation. An example of a secondary physical stressor is removal of riparian
 (streamside) vegetation that not only alters habitat structure and favors shade-intolerant
 tree species directly, but also can have secondary impacts such as increased siltation of
 stream bottoms and higher" water temperatures.   .                      -
   Analysts knowledgeable about a particular environmental problem should be able to use
 their best professional judgment and experience to identify the most important stressors for
 each problem area in terms of its prevalence, persistence, and/or toxicity. The group of
 stressors selected for each problem area should be representative. This will ensure that the
 analysis will encompass the most serious risks, rather than risks from inconsequential stres-
 sors. Data availability and quality may also be a consideration in selecting stressors.
   Table 2.3.1 shows some of the more commonly used stressors and likely sources for the
 ecological problem-area list that EPA has used for a number of regional and state projects.
 This table merely suggests a number of candidate stressors and is not meant to be compre-
 hensive or definitive. Each project must sort through its own unique set of stressors to
 identify the most important ones.'

 Task 2:  Estimate Exposures/Co-occurrence
   To characterize ecological risk, there must be a stressor present with the' ability to cause
 an adverse effect to an ecological receptor. The magnitude and length of exposure is
 important in calculating risk, but the timing of the exposure is also important. For
 instance, if the stressor is episodic (e.g., pesticide use), then different species and life stages
 may be affected. Likewise, the location of contact can also be critical to the magnitude of
 stress experienced by receptors, such as important habitats or breeding areas along a
 transcontinental flyway or a.spawning area for anadromous fish species. Stressors are also  i
 affected by the environment which in turn can modify the exposure of ecological recep-
 tors. For instance,  siltation and sedimentation depend not only  on sediment volume, but
 also on water flow and the stream's physical characteristics. Similarly, chemical stressors
 can be modified through biotransformation by microbial communities or other environ-
 mental-fate processes, such as photolysis and hydrolysis.
   The most common way of estimating exposure is to analyze measured concentrations
 or amounts of a stressor in terms of assumptions about its co-occurrence, contact, or
 uptake by ecological receptors most  likely to be affected by it. For example, the exposure
 of aquatic organisms to chemical stressors is often expressed as the stressors, concentration
 in the aquatic environment; the aquatic organisms (receptors) are assumed to come in
contact with the stressor. In the case of physical stressors, such as physical alteration of
communities and ecosystems, exposure by ecological organisms  that normally use the
habitat is assumed and is expressed in terms of the area of co-occurrence.
2.3-14                                                              September 1993

                                                    2.3 Comparing and Assessing Ecological Risks
                                     Table 2.3.1:
                  Ecological Problem  Areas, Stressors, and  Sources
Problem Areas
Industrial Waste-Water
Municipal Waste-Water
Aggregated Drinking
Non-point Source
Physical Degradation of
Water/Wetland Habitats
Aggregated Ground Water
Underground and Surface
Storage Tanks
Active Hazardous
Waste Sites (RCRA)
AbandonedHazaidous .
Waste Sites (Superfund)
Municipal Solid
Waste Sites
Industrial Solid
Waste Sites
Accidental Chemical •
Physical Degradation
of Terrestrial Ecosystems
and Habitats
Environmental Lead
Noise Pollution
Total suspended solids, biological oxygen '
demand (BOD), toxic organics and inorganics,
pthalates and phenols, and thermal pollution
' Industrial waste- water discharges, plus
ammonia, chlorination products, nutrients
No significant ecological risks •
Dirt and debris, toxic substances, leachate,
storm water and urban/agricultural runoff
Physical changes to water-flow quantity and
patterns, and impacts to aquatic habitats
Nutrients, toxic inorganics and organics, salts,
oil and petroleum products, and microbes
Releases of oil and non-petroleum products,
such as motor fuels, heating oil, solvents,
and toxic organic lubricants
TCE/FCA, toluene, and toxic organics,
such as heavy metals and PCBs
Similar pollutants and mixtures to RCRA site;
plus radiation from "mixed waste"
Nutrients, BOD, microbes, toxic chemicals;
air Stressors include air toxics lind paniculate
Similar Stressors to municipal solid waste
sites, but the concentrations, volumes, and
mixtures differ markedly
Stressors released during transport or while
stored include petroleum products, acids, and
other toxic chemicals
All types of herbicides, insecticides,
fungicides, neman'cicles, and rodenticides
Physical alteration or destruction of natural
terrestrial "wfystems, habitat fragmentation
migration path blockage, and Utter .
Airborne lead and lead deposition in soil and
No significant ecological risks
Metal finishing, pulp and paper pro-
cessing, and; iron and steel produc-
tion (all NPDES permitted sites)
Discharges from publicly and
privately owned water treatment
, plants, and sewer overflows
Not applicable
Runoff from agricultural, urban,
silviculture, industrial, and dis-
Channelization, levees, irrigation
and other withdrawals, flood
control, ami urban development
. Waste sites and landfills, UST's anc
UIC's, road salts, leachate from
septic systems, and runoff
Farm fuel tanks and grain silos,
. home fuel tanks, gasoline stations,
and other storage
Open and closed landfills, surface
impoundments, storage tanks, and
waste from incinerators
Any abandoned site that is a candi-
' dale or listed NPL site, or state
priority list site
Open and closed municipal landfills,
sludge and refuse incinerators, and
surface impoundments
Industrial waste sites, open and
closed industrial landfills, surface
impoundments, and incinerators
Explosions :u industrial plants, and
releases during air, land, or sea
Agricultural, suburban, and urban
application, runoff, and oversprays;
food-chain impacts
Urban/suburban sprawl, conversion
to other uses, highway construction,
and building resorts
Tfftrird gasoline, landfills, surface
impoundments, other contaminated
sites; food-chain impacts
Nat applicable
September 1993

 A Guidebook to Comparing Risks and Setting Environmental Priorities
                             Table 2.3.1 (continued):
                  Ecological Problem Areas, Stressors, and Sources
Problem Areas
Sulfur Oxides and
Nitrogen Oxides
Ozone and.
Carbon Monoxide
Paniculate Matter
Toxic Air Pollutants
Indoor Air Polluiams
Other Than Radon
Radiation Other
Than Radon
Indoor Radon
Global Warming and
Climate Change
Ozone Depletion
Acid deposition, which results from the
chemical transformation of sulfur and nitrogen
Ozone and carbon monoxide
Fine particulates (PM-40) and
total suspended particulates
Asbestos, various toxic metals, organic gases,
gasoline vapors, incomplete combustion
products, polycyclic aromatic hydrocarbons
No significant ecological Ti^lcg
Ionizing and non-ionizing radiation
No significant ecological risks
Carbon monoxide, carbon dioxide, methane,
nitrous oxides, and chlorofluorocarbons (CFCs)
Nitrous oxides and chlorofluorocarbons (CFCs)
Wide variety of industrial, commer-
cial, and residential fuel, and related
combustion sources
Both 'mobile (e.g., autos) and station-
ary sources similar to those for sulfur
and nitrogen oxides
Similar to those for sulfur/nitrogen
oxides plus strip or open mines in
some locations
Same as those mentioned above
Not applicable
Radio/TV frequencies, power lines,
radar, microwave transmitters, high-
and low-level radioactive wastes
Not applicable
Mobile and stationary sources of fossil
fuel production and combustion,
landfills, and agricultural practices
Industrial processes, coal, oil, and gas
combustion, fertilizer use, deforestation
   Estimates of exposure should be based on the most likely scenarios, rather than on
worst-case scenarios. The analysis should emphasize the most important, or "dominant,"
pathways of exposure. For example, pesticide use can harm terrestrial organisms that enter
fields following application or because of overspray on adjoining lands. However, the
dominant pathway of exposure for pesticide use may be runoff into aquatic habitats.
While potential impacts to terrestrial animals arid plants should be mentioned, the analy-
sis should focus on impacts to aquatic organisms and habitats in this instance.
   Finally, an analysis of uncertainty is an integral part of the analysis. In the majority of
analyses, either data will not be available, or the data that are available may be of question-
able or unknown quality. Typically, the analyst will have to rely on a number of assump-
tions to characterize exposure based on a combination of professional judgment, inferences
based on similar instances of exposure, and estimating techniques—all of which contribute
to the overall uncertainty of the estimate. It is crucial that the various sources and  kinds of
uncertainty are carried forward and noted in the third (risk characterization) phase.
September 1993

                                                   23 Comparing arid Assessing Ecological RisJts
 Task 3: Characterize Ecological Effects
   The next task is to combine information about the magnitude, timing, and location of
 exposure by ecological receptors of concern to various stressors. The dsita used to character-
 ize ecological effects depend largely upon the nature of the stressor and the ecological recep-
 tor of concern. Ecological effects range from mortality of an individual species to disrup-
 tions in the structure and function of entire ecosystems. If possible, these ecological effects
 should be quantified,  but often the relationship can only be described non-quantitatively.
   Ecological effects can be analyzed at any level of biological organization (i.e., individ-
 ual, population, community, and ecosystem). In fact, using data about ecological effects
 among different biological levels is recommended since each level is likely to provide only
 part of the overall "picture" of risks posed to-an ecosystem and communities. For example,
 ecological effects might be measured in terms of the reproductive impairment of a given
 population; the changing structure of a community of plant and animal species; or the
 functions provided by ecosystems, such as nutrient and energy cycles.
   Sources of ecological effects data include field observations (e.g., fish or bird kills), field
 tests (e.g., microcosm or mesocosm tests), conitrolled laboratory tests (e.g., single species),
 and chemical structure-activity relationships. For chemical stressors, a combination of
 modeling and monitoring data is often used; for non-chemical or physical stressors, data
 provided through ground reconnaissance, acrid photography, or satellite imagery can be
 used. In either case, it is often necessary to use professional judgment to supplement exist-
 ing data.                                   I  ..                   '            •
  ' Ecological risks can be described quantitatively (e.g., there is a bettor than 50 percent
 chance of 20-30 percent mortality in a given population) or non-quantitatively (e.g., there
 is a high likelihood of mortality occurring in this population). Information on the types
 and magnitude of uncertainty can provide risk managers and decision makers with greater
 insight into the strengths and weaknesses of the analysis. This knowledge can also indicate
 problem areas where further research to reduce uncertainty may be worth the investment,
as opposed to other environmental problems with relatively little uncertainty where
 response actions can be implemented immediately.   •

  The third phase of a comparative ecological risk analysis involves using the results of
the analysis phase to characterize the environmental risks posed by problem areas. Risks
 are characterized by pulling together all the information gathered and analyzed about
stressors, receptors, and ecological effects. This information is typically described in terms
of the number of acres or stream miles at risk, measured concentrations of stressors found
in the environment, the magnitude and severity of effects, their spatial arid temporal dis-
tribution, arid the ecosystem's recovery potential and rate. Risk characterization also
 includes a summary of assumptions and scientific uncertainties.
                            • i                                       •
  For most problem areas, professional judgment will have to supplement existing data in
terms of extrapolating or interpolating information from other studies;, All of these judg-  •
September 1993

 A Guidebook to Comparing Risks and Setting Environmental Priorities  •
 mems introduce uncertainty and imprecision to the analysis, but they also help analysts
 more fully and clearly describe the extent and severity of the impacts and potential risks to
 the environment. For example, an observed ecological effect might be the decreased repro-
 duction of peregrine falcon hatchlings.in areas of high pesticide use. In addition, lab tests
 may indicate that pesticides are also lethal to many other organisms, such as field mice and
 microbial organisms, that occupy the same habitat and that may be indispensable for that
 particular ecosystem to function normally. Therefore, the work group might determine
 that pesticides pose serious "threats not only to  highly visible and endangered species like ,
 the peregrine falcon, but also to the entire ecosystem.
   While these latter effects may not .capture the general public's attention, they may be
 far more important  ecologically. This exemplifies the divergence that can sometimes
 occur between the social or political significance of an ecological receptor and its biologi-
 cal significance. Creating a risk communication dialogue between the scientific commu-
 nity and the public can make die risk analysis  process an educational opportunity for all
 panics involved.

 Task It Summarize Each Problem Area Using Evaluative Criteria
   The first task of die risk characterization phase is to characterize each problem area in
 terms of the evaluative criteria. This should be done for each ecosystem or geographic area.
 If the project is partitioned into ecosystems, then the ecological risks to each ecosystem
 would be scored or described; if the project is partitioned by geographic area, then each
 geographic area would be scored or described. Table 2.3.2 provides a hypothetical example
 of this to describe the impact of pesticides in different geographical areas of California. This
 would be done for each problem area and, preferably, during work group meetings.

                                     Table 2J.2:
                            Hypothetical Pesticide Example
Calif. Desert
Sierra Nevada
Los Angeles
Bight Habitat
San Joaquin
Area of Impact
, Low
Medium ~
Severity of Impact
Low v
   Criteria can be described narratively or scored numerically. There are advantages and
disadvantages to each approach. The advantage of the narrative description approach is its
September 1993

                                                     2.3 Comparing ami Assessing Ecological Risks
  simplicity and flexibility. It does not tie work group members to a rigid formula. For less
  quantitative members, it is likely to be more comfortable and intuitive to discuss risks and
  impacts in common terms. The disadvantage of this approach is that because project par-
  ticipants may not weigh evaluative criteria consistently, the final ranking may not be
  replicable if done by another group of people using the same information. It is also diffi-
  cult to backtrack through the rationale for the ranking if the only reason given for deci-
  sions is that it was the "sense of the group."  Table 2.3.3 provides another example of how
  this narrative approach might be assembled  to describe the ecological impacts of pesti-
\ cides. The descriptions in the table are purely conjectural.

                  1             '    Table 23.3:
                   Hypothetical Narrative Description for Pesticides
Coastal -
Calif. Desert
Sierra Nevada
Los Angeles
Bight habitat
San Joaquin
Total Risk
Total Risk
Medium Low
Potentially large area "at risk," but
not a serious threat to ecosystem.
Almost entire area affected at high
dosages; serious, widespread impacts.
Small area "at risk," but potential
threat is serious; fragile ecosystem.
Low probability of impact; not con-
sidered a serious threat to ecosystem.
Impacts unknown, bat large area "at
risk"; diverse, fragile ecosystem.
Entire area affected at high dosages; .
serious, widespread impacts.
Serious, but reversible damages.
Affects large area, but not entire state.
    Alternatively, the ecological work group might feel more comfortable attaching numer-
  ic values or "scores" to each criterion. In contrast to narrative descriptors, numeric values
 . can be manipulated mathematically arid resolved to a single number. Thus, ecological risk
  can be expressed as a mathematical formula that is designed to increase: as the size of the
  area affected increases, the severity of the effect increases, and/or as the length of recovery
  by the ecosystem increases. Various weights can be attached to each criterion by placing
  coefficients in front of the variables to reflect their relative importance. The results can
  then be compared for different problem areas.  The disadvantage of this type of formulaic
  approach .is that it can convey a false sense of certainty and precision. In addition, the
  public may not relate to a complex formulaic approach, and this could discourage public
  participation and interest.  Exhibit 2.3.6 shows how numeric values can be used instead of
  narrative descriptors.                        i
    The approach selected will depend upon the preferences and objectives of those design-
  ing  the project. Numeric or narrative scoring systems can both effectively organize and
  summarize large volumes of information, and they force people to evaluate the impacts of
  problem areas more systematically and consistently. However, they only reflect the collec-
  tive judgments of those assigning values to them, and they are only as sound as the under-
  September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
lying analyses. Scoring systems should not. obscure this fact or become so elaborate as to
be unintelligible to the public.

                                   Exhibit 23.6:
                 Narrative and Numeric Scales for Evaluative Criteria
                 Desciption of Severity
   Very High
Ecosystem structure and function are severely damaged and
fundamentally changed by stressor(s). Ecosystem is rendered
virtually lifeless.
Ecosystem structure and function are seriously damaged by
stressor(s). Species populations decline and communities change.
Habitats and abiotic resources are lost.
Ecosystem structure and function are adversely affected by
stressor(s). Impact is infrequent or intermittent; individuals may
die, but populations are not at risk; habitat is intact.
Ecosystem structure and function are exposed to stress, but the
structural and functional integrity are intact Temporary and mild
impacts to species individuals or habitats occur.
Ecosystem structure and function are not exposed to stress, or
expression of stress is not measurable or adverse.
 Task 2: Summarize the Bisk to Each Ecosystem or Geographic Area
   The second task is to summarize the overall risk to each ecosystem or geographic area
 in terms of all the evaluative criteria. This value represents the "total" risk to each ecosys-
 tem or geographic area. Building upon the previous information on .pesticides only,
 Exhibit 2.3.7 provides an example of how this information can be integrated into a larger
 matrix that includes all the problem areas.

 Task 3: Aggregate Risks Across Ecosystems or Geographic Areas
   The third task is to aggregate the risks for each problem area across all the ecosystems
 or geographic areas within the study area. The bottom row of Exhibit 2.3.7 depicts the
 total hypothetical risks associated with pesticides.
   There is no "correct" way of aggregating the values across ecosystems or geographic areas.
 However, a number of methods and approaches, such as group discussion and consensus
 building, have already been discussed. Given the broad mandate to set general environmen-
tal priorities on the basis of risk, participants in past comparative risk projects have been
 able to reach agreement on rankings and make these distinctions with some confidence.
   As was stated at the outset of this discussion of the risk characterization phase, it is not
                                t          .                        •*
 important where the distinction is drawn between risk characterization and comparing
 and ranking problem areas.  It is a single process that must be conducted in a sequential
                                                     September 1993

                                                   2.3 Comparing and Assesstng'Ecological Risks
 order of steps. The steps described in this section provide the raw material for comparing
 and ranking problem areas.

                                    Exhibit 2.3.7:
                Summary Table of Ecological Risks Across All Problem Areas
nple Environmental
)iem Lead ,
e*s Hazardous Waste
Non-point Source
F Sulfur Oxides and
Nitrogen Oxides
Physical Degradation of
Aquatic Habitats
Total Risk by
Geographic Area
• ' ' " ' ^
V v '^V \ < \ \V
VA\ \\ \ \VV\V-.









i; ,   •                                      ;' •
   The final phase of a comparative ecological risk analysis involves comparing and rank-
 ing the ecological risks posed by different problem areas. This is done by considering the
 ecological impacts and risks for each problem area in terms of all the evaluative criteria
 taken together and comparing them to the other problem areas. Problem areas are then
.grouped into several broad categories of relative risk using a consensus-building process.
 Professional judgment plays a critical role, but the level of precision required is only
 enough to make rough relative comparisons, rather than absolute estimates, of risk.
   During the comparison and ranking phase, the total risk values for each problem area
 that have been described are assembled into a matrix. At this point, with all the informa-
 tion in the problem area risk characterizations and evaluative-criteria summary tables at
 their disposal, the ecological work group,  steering committee, or public advisory board can
 rank problem areas. The methods and ranking approaches discussed in Section 2.1 can be
 used and adapted to each project. A matrix can also be used to identify those ecosystems
 or geographic areas at greatest risk.
   The resulting ecological ranking is used as ail important input to the risk management
 process, which takes into consideration relevant non-risk factors in addition to the risk
 ranking results to help set  environmental priorities.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
1  The term "receptor" is used here for ease of understanding. However, in other technical
documents it has been replaced by the term "ecological component" because some believe
that this term communicates the tact that ecological risk assessments focus on components
of ecosystems at higher levels of biological organization than the individual organism. As
used here, the two terms are synonymous.

Colorado. Department of Health and Department of Natural Resources. Environmental
Status Report: A Summary of the Technical Analysis of the Colorado Environment 2000
Project. June 1990.
Hawaii. Center for the Department of Health. Hawaii Environmental Risk Ranking
Study: Environmental Risks to Hawaii's Public Health and-Ecosystems. Prepared by East-West
Center. Honolulu, HI. September 1992.
Michigan. Department of Natural Resources. Michigan Relative Risk Analysis Project,
Michigan's Environment and Relative Risk. July 1992.
Suter, Glenn W, II. "Endpoints for Regional Ecological Risk Analysis." Environmental
Management, vol. 14, no. 1 (1990): 9-23- Oak Ridge, TN: Oak Ridge National
U.S. Environmental Protection Agency (U.S. EPA). Office of Research and
Development. Risk Assessment Forum. Framework for Ecological Risk Analysis.
Washington, D.C. February 1992.                                      '
U.S. EPA. Risk Assessment Forum. Peer Review Workshop Report on a Framework for
Ecological Risk Analysis. Prepared by Eastern Research Group, Inc. Washington, D.C.
September 199 la.
U.S. EPA- Office of Pesticide Programs. Ecological  Effects Branch.  Comparative
Ecological Risk Analysis: A Review and Evaluation of EPA Regional Methods. Washington,
D.C. January 1991 b.
U.S. EPA. Region VI Headquarters. Office of Planning and Analysis. Comparative Risk
Project, Appendix A. Dallas, TX. November 1990a.
U.S. EPA. Science Advisory Board.  Reducing Risk: Setting Priorities and Strategies for
Environmental Protection, Appendix A. Washington, D.C. September 1990b.
U.S. EPA. Office of Policy, Planning and Evaluation. Office of Policy Analysis. Review of
Ecological Risk Analysis Methods. Washington, D.C. November 1988.
U.S. EPA. Regional and State Comparative Risk Project Approaches for Ranking Based on
Ecological Risk/Impact. Prepared by ICF, Inc. Washington, D.C. December 1987a,
2.3-22                                                            September 1993

                                                 2.3 Comparing and Assessing Ecological Risks
U.S. EPA. Office of Policy, Planning and Evaluation. Review of the Literature on Ecological
End Points. Prepared by American Management Systems, Inc. Washington, D.C.  .
September 1987b.                         ,;                     ;     .     •    '.
U.S. EPA. Office of Pplicy, Planning and Evaluation.'Office of Policy Analysis.
Unfinished Business: A Comparative Assessment of Environmental Problems, Appendix II.
February 1987c.             ..-'.'-        :                    ' ,i .              ,
Vermont.  Agency of Natural Resources. Environment 1991: Risks to Vermont and     •
Vermonters. Report by the Public Advisory Committee, The Strategy for Vermont's Third
Century. Waterbury, VT. July 1991.
September 1993                                                            2.3-23


A Guidebook'to Comparing Risks ami.Setting Environmental Priorities
 .  2.4.1' Vermont's Problem Areas andjQuality-of-Life Criteria  	I	7
   2.4.2  Quality-of-Life Effects Measured in EPARegional Projects	,...10
   2.4.3  Healrih Effects and Associated Health-Care Costs (1990 $)	 15
   2.4.4  Willingness to Pay for Recreational Fishing	;		,	.18
   2.4.5  EPA Region I Presentation of Results  |	29
   2.4.6  Sample Summary Table  —	.'.'.;			31
   2.4.7  Louisiana Quality-of-Life Damages Matrix	...32

                                    .  •    '    I     •       -    .   "':'-"   •-
   2.4.1  Steps in Quality-of-Life Analysis,......:....	...4
   2.4.2  Criteria Used to Assess Quality-of-Life Impacts	:		5
   2.4.3  Descriptions of Vermont's Quality-of-Life Criteria	.......;	.......	.6
   2.4.4  Louisiana's Quality-of-Life Ranking Process	...	—	30
END NOTES	...:...;.	.:.........	....;...........:	35
September 1993


Step 1: Identify Impacts and Determine Community's Values	4
                                      *          "'..-,"                  •
Step 2: Identify andDefine Evaluative Criteria....	5

Step 3: Collect and Analyze Data on Impacts	.--8
     Sources of Data	•	8
     Analytic Methods	•	••••••	8
       Damages to Materials	«	;"9
       Commercial Harvest Losses	•	...........11
       Health-Care Costs	•	•	....14
       Recreational Losses	•••>	.16
       Aesthetic Damages and Visibility Damages	-.19
       Property-Value  Losses	•••••	-21
       Resource-Restoration Costs.	'......-.	22

Step 4: Characterize Impacts for All Problem Areas	.	•	'...25
     Long-Term Damages	•	•	25
     Discount Rate	•	•	•••••	27
     Services From Ecosystems	27

Step 5: Present Findings and Rank Problem Areas	•	.-..28,
     Establishing an Integrated Ranking....	.'.	•••••	--28
     Summary Tables	•	31

Step 6: Evaluate Risk Management Issues	•	•••33
September 1993                     .                    '                   2'4"1

 A Guidebook to Comparing Kilts and Sitting Environmental Priorities
 pristine natural resources far from their daily existence. Amo'ng the damage categories,
 health-care costs can have a larger impact on a low-income community if the costs consume
 a greater portion of the populations income. Many low-income families have no health-
 care insurance, leading to an even greater economic burden and added social stress.
   The Seattle Environmental Priorities Project illustrated the importance and complexity
 of addressing community values in comparative risk assessment:
      Transportation sources of air pollution, wood burning, and environment.^ tobacco smoke
      are driven largely by individual choices that, cumulatively, pose significant risks to public
      health, the environment, and die overall quality of life in the city. What is die appropriate
      balance between individual values (such as personal mobility, convenience, and individual
      preferences) and community values (such  as public health and environmental quality)? 'What
      is the city's role in identifying and achieving this balance?
      The information on quality-of-life risks is sparse at best. Many of these impacts are not
      measurable, at least not in a way that most people find meaningful; consequendy, die
      Technical Advisory Committee's consideration of quality-of-life risks is entirely non-quan-
      titative. The committee, no ted  the type or types of quality-of-life concerns associated with  •
      each issue, and made judgments about the scale, severity, and reversibility of chose concerns
      (Seattle 1991),                         *  !                     :
   The process for assessing social and economic impacts is still being developed.
 Nevertheless, Exhibit 2.4.1 indicates a logical progression of information gathering and
 analysis. The following sections discuss these steps in detail.

                                   Exhibit 2.4.1:
                         Steps  in Quality-of-Life Analysis
              Step 1: Identify impacts and determine the values of the
                       community.          j
                                             i                 •    ,
              Step 2: Identify and define evaluative criteria.
                                             i      •
              Step 3: Collect and analyze data on impacts.
              Step 4: Characterize impacts for all problem areas.
              Step 5: Present findings and rank problem areas for
                       quality-of-life impacts.  •
                                             i       '       .
              Step 6: Analyze future environmental conditions and
                       risk management consideratons
   The values of a community, are the basis for an analysis of the impacts of environmental
problems on the quality of life. This step is important to ensuring that the process has
September 1993

                                                            2.4 QuaJiiy-of-Li/e Assessments
        Computing the costs to society of continued pollution is in the interest of the gov-
        ernment and the environmentally concerned community. This information can
        underscore the role of environmental quality with regard to sustained economic
development and quality of life. In addition to the economic benefits of more traditionally.
recognized natural resources, such as oil, gas, minerals, and wood, ecosystems provide
numerous services that would be extremely cosdy or impossible to replace. These include
purifying polluted water (wedands), producing oxygen (green plants), and protecting die
earth against harmful ultraviolet radiation (the stratospheric ozone layer).
   Comparative risk projects usually include an evaluation of the impacts of environmen-
tal problems on the quality of life. Historically, these evaluations have cpncentrated on
economic impacts that can be readily quantified in dollars, such as health-care costs* crop
losses, and damage to materials. These evaluations are particularly important to decision
makers who must justify the expense of environmental protection measures to groups who
are concerned widi losing jobs  or profitable business opportunities. In some cases, the
information gathered can demonstrate that environmental protection may actually save
money and maintain or create jobs.                          ,            >
   Participants in die quality-of-life ranking usually include legislators and other govern-
ment officials, educators at all levels, environmental groups, local industries and utilities,
members of the general public, and spiritual, ethnic, and cultural leaders who represent
the community's values.
   This chapter encourages expanding quality-of-life analyses to include die values and
social concerns of the community affected  by the environmental problems, commonly
missed in studies limited to health, ecological, and economic concerns. These values
include spiritual, cultural,  and aesthetic values, concern with the fairness of an environ-
mental problem's impact on specific populations or future generations, and the value of
one's sense of community.  Relevant social impacts should be discussed explicitly, and deci-
sions should be made regarding how best to describe, evaluate, and communicate the least
quantitative elements of environmental effects on the  quality of life.
   Environmental equity should be considered throughout the assessment process. If the
area under study includes a diversity of people and life styles, it may be necessary to pay
particular attention to potentially serious, impacts on particular groups of people. This topic
is covered in more depth in Section 2.1 of this document, but is mentioned here to  empha-
size aspects of the quality of life diat differ among cultural and economic groups. For exam-
ple, the loss of animal habitats or sacred lands may adversely affect Native Americans' tradi-
tional life styles and,  hence, their quality of life. Also, communities diat depend on a single
natural-resource-intensive industry, such as  fishing or logging, are at risk if non-sustainable
practices jeopardize their livelihood. Cultural and income differences may affect the base-
line values used to evaluate impacts on quality of life. Willingness-to-pay models may have
to be adjusted in light of different social norms. For example, residents of stressed urban
communities may be more interested in enhancing their immediate environment (e,g.,
urban parks and cleanup of abandoned industrial plants) than in preserving biodiversity or
September 1993                                        .                       2.4-3

   A Guidebook to Comparing Risks art Setting Environmental Priorities
                                      Exhibit 2.4 3:
                    Descriptions of Vermont's Quality-of-Life Criteria
    Impacts on Aesthetics
    Economic Well-being
   Future Generations
   Peace of Mind
  Sense of Community
                                            Descriptions of Criteria
  Reduced visibility, noise, odors, dust, and other unpleasant
  sensations, and visual impact from degradation of natural or
  agricultural landscapes.

  Higher out-of-pocket expenses fix, replace, or buy items or
  services (e.g., higher waste disposal fees, cost of replacing a
  well, higher housing costs), lower income or higher taxes paid
  because of environmental problems, net jobs lost because of
  environmental problems, and health-care costs and lost
  productivity caused by environmental problems.          •

  Unequal ;distribution of costs and benefits (e.g;, costs and
  benefits may be economic, health, asethetic).

  Shifting the costs (e.g., economic, health risks, environmental
  damage) of today's activities to people not yet able to vote or not
  yet bom.         »

 Feeling threatened by possible hazards in air or drinking water
 or potentially risky structures or facilities (e.g., waste sites
 power lines, nuclear plants), and heightened stress caused bv
 urbanization, traffic, etc.

 Loss of access to recreational lands (public and private), and
 degraded quality of recreation experience (e.g., spoiled'
 wilderness, fished-out streams).

   '    •'             ;      -   \' ,    ,.     ;   '   -     '
 Rapid growth in population or number of structures, or
'development that changes the appearance and fesl of a town- loss
 of mutual respect, cooperation, ability, or willingness to solve
 problems together; individual liberty exercised at the expense of
 the individual; and loss of Vermont's landscape jmd the
 connection between the people and the land.

                                                                        September 1993

                                                            2.4 Qualiiy-of-Ltfi Assessments
broad support and represents public concerns accurately. Surveys, questionnaires, and pub-
lic meetings arc among the tools sometimes used to help reveal impacts and define commu-
nity values. Major differences of opinion within values should be noted. Once the work
group has gained a sense of die range of impacts .and the community's values, the "extent to
which those values are degraded  by impacts to environmental quality must be evaluated.
Determining the values of the community involves: "working with community members to
define "quality of life," then asking: what social values are most important in the communi-
ty, which can be affected by environmental problems, and which will be important consid-
erations when  the community evaluates management strategies?"(NCCR 1992)
  The Strategy for Vermont's Third Century (Vermont 1991) used public meetings, a
survey, and research to determine shared .values among Vermonters:        .
     After holding 11 public forums, conducting an informal public survey, and reviewing several
     statewide opinion  polk, die Advisory Committee concluded that most Vermonters share a
     similar set of values relating to their environment. The committee adopted these as its seven
     quality-of-lifc criteria. [They are listed and defined in Step 2 of this section.]
     Because most of these seven criteria are intangible, they are extremely difficult to'measure or
     quantify. The Quality-of-Life Work Group described how each problem area affects each crite-
     rion and how widespread or intense die effects are. Ahhough diese non-quantitative descrip-  ,
     dons of risk often lack precision and scientific objectivity, diey focus attention on specific criti-
     cal issues and dius  are useful tools for comparing die problems systematically and consistently.

  Criteria can be derived from broadly shared public values and applied to each problem
area to determine how quality of life is affected. Comparative risk projects have varied in the
criteria considered for quality-of-life impacts—from studies limited to the economic impacts
of environmental problems, to those that included several social issues as well. Exhibits 2.4.2
and 2.4.3 and Table 2.4.1 list the criteria used by three comparative risk projects.

                                  Exhibit 2.4.2:
                 Criteria Used to Assess Quality-of-Life Impacts
    (Qualitative Aspects of Losses)
     • Number of People Affected
     • Severity of Effects on
       Specific Populations
     • Availability of Substitutes
     • Reversibility of Effects
     • Unaccounted Damages
(Categories of Quality-of-Life Impacts)
• Reduced Recreational Opportunities
• Reduced Aesthetic Value
• Reduced Economic Opportunities
• Loss of the Intrinsic Value of Future
  Use of the Resource Affected
September 1993

 A Guidebook to Comparing Risks and Setting Environmental 'Priorities
                            •  ,         '   '    ,  •  '      ' '          4      •-'.-.
    Once criteria have been selected, the challenge is to find a way to measure the damage
 from each problem area. Projects may include both quantitative and non-quantitative
 analyses. The point is to have a well-defined analytic framework and a consistent set of
 criteria to apply to each problem area. The analytic methodology should be agreed upon
 in advance and documented as it is used for each problem area. Chapter 2.1 of this docu-
 ment provides more detail on general analytic structure.
                       ,.                      /         •            f
 Sources of Data
    The data used'to measure the criteria reflect the values of the affected community. The
 data usually fall into one of several categories:  ,  !
    Survey Responses. The range of data and units of measure in a survey are defined by the
 questions asked. For example, if a survey asks respondents to describe how air pollution
 affects the quality of life, a broad range of responses  could be anticipated, including prob-
 lems related to health, visibility, soiling, and psychological well-being. Units of measure for
 the responses might include the number of people reporting health problems, days of work
 missed, days with limited visibility, or days between  visits to the carwash. jMternaiively, if a
 survey asks how much money the respondent spent  last year on health car: related to air
 pollution, the only likely unit in the responses will be dollars.
   Public Opinion Polls and Census Data. Information from these sources can help to indi-
 cate trends for the future of the area and can supplement other more direct data in deter-
 mining community values.                     i
   Anecdotal Information. Responses from public meetings, surveys, etc, can be used in
 descriptive discussion of problem areas and in determining the values of the population.
    Willingness-to-Pay Studies. For impacts on aesthetic and recreational values, willingness-
 to-pay studies have been used to provide a measure of damages in dollars.
   •Direct-Cost Data. This category includes information on health-care casts, crop loss,
 and structural damages that may be gathered from local sources or extrapolated from stud-
 ies done elsewhere.                             !
   Non-market Data. This category includes measures of reduced visibility, noise levels,
 dust, unpleasant landscapes, and stress and related social disturbance. Vermont used inno-
 vative units of measure, such as "number of boil-water days," to measure losses due to tur-
 bidity of surface water, and photographs to indicate  visibility loss due to air pollution.
 Days with public health advisories for air quality and bans on recreational and commercial
 fishing are other potential  units of measurement.  J  .
                                              j     '               I
Analytic Methods'
   Analytic methods should include as comprehensive a picture as possible of the nature
and extent of present and anticipated  economic and social impacts caused by environmen-
tal degradation. However, models to predict future impacts are often unavailable or are

2.4-8                                         !    ;                 September 1993

                                                              2,4 Quality-of-Lift Assessments
                                       Table 2.4.1:
                   Vermont's Problem Areas and Quality-of-Life Criteria
Problem Areas
Alteration of Ver-
mom's Ecosystems
Global Climate
Indoor Air Pollution
Air Pollution,
Including Acid Rain
Depletion of the
Ozone Layer
Drinking Water
at the Tap
Pollution of Lakes.
Ponds, and Streams
Toxics in the
Toxics in the
Hazardous- and
Radioactive Waste
SoEd Waste
Visual and Cultural
Degradation of
Vermont's Built and
Natural Landscapes
Food Safety
Loss of Access to .
Outdoor Recreation
Pesticides & Pests
Vermont Quality-of-Life Criteria ,
. . . Economic Future Peace of „ . Sense of
Aesthetics WdH)dng Fairness c^^^ ^ Recreation Community























September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
region, or country (EPA 1986). Several EPA economic damage studies have used the fol-
lowing equation to estimate damages for total suspended particulates (TSP): '
      (Average TSP Level in ug/m3 - Background TSP Level in ug/m3) x Number olf Households -
           x Damages per Household per ug Change in Annual Mean TSP • Damages
   The average TSP level can be derived by taking the mean of recorded TSP at all moni-
toring stations in the given state, region, or country.2  Damage per microgram change in the
annual geometric mean of TSP has been calculated to be roughly $1 per capita (1990 $).
   This approach has only been applied with respect to paniculate matter. Another
approach that has been used to quantify damages to  materials from a number of pollutants
involves combining'national estimates of per-capii:a damages with the population of the
relevant state,or region in the following fashion:
       Annual National Per-Capita Damages x Population of Region/State • Annual Damages
                             Table 2.4.2:
           Quallty-of-Llfe Effects Measured In EPA Regional Projects
Problem Areas
Industrial Waste- Water
, Municipal Waste-Water
Aggregated Drinking Water
Aggregated Ground Water
Non-point Source Pollution
Physical- Degradation of
Water/Wetland Habitats
Municipal Solid Waste
Industrial Solid Waste
Underground Storage Tanks
Active Hazardous Waste
Sites (RCRA Program)
Abandoned Hazardous
Waste Sites (Superfund)
Accidental Chemical
SOx, NO*, and Acid Rain
Enviroriinental Lead
Ozone and Carbon Oxides
Paniculate Matter
Hazardous Air Pollutants
Indoor Air (Except Radon)
Indoor Radon
Criteria' Air Pollutants
Strat. Ozone Depletion
CO2 and Global Wanning
Physical Degradation of
Terrestrial Habitats
1. 2, 3, 4, 6

3, 4, 6
1, 2, 3, 4, 6

1. 2, 3. 4, 6




1, 2, 3, 4, 6

1. 2, 3, 4, 6


• ,












4 ,





1 •





September 1993

                                                            2.4 QuaUtyt-of-Ufe Assessments
difficult to fit to existing data. Also, certain economic and social impacts, such as chose
from lost ecosystem services, may clearly exist, but may be very difficult to measure. Other
impacts, like ozone-related crop damage or damage to materials from acid deposition*, are
relatively clear and measurable. Additionally, some analytical methods (e.g., willingness-
to-pay studies) may be controversial, especially when results are presented to people with-
out an extensive knowledge of economics.
   Which economic and social impacts to assess, which analytic methods.to use, and
whether to explore future impacts are among the early decisions of a quality-of-life work
group. In addition to the traditional measures of economic and social damages discussed
in this chapter, the work group may want to consider other aspects of the extent and sever-
ity of impacts on human communities, including:
   • Lost benefits from ecosystems and other natural resources damaged by environ-
     mental degradation.
   • The impact of social and economic trends on the environment.
   Seven categories of economic damages have been applied in past studies: (1) damages to
materials; (2) commercial harvest losses; (3) health-care costs; (4) recreational losses; (5)
aesthetic damages; (6) property-value losses; and (7) remediation costs. The first five cate-
gories measure economic losses relatively directly. The last two categories—economic
losses due to decreased property values and the economic costs of restoring contaminated
resources—must be used carefully because they (1) may capture many of the same eco-
nomic damages estimated by the direct methods and (2) may poorly reflect actual eco-
nomic damages. Property-value losses and remediation (resource restoration) costs can be
used as an alternative or a complement to the more direct damage measures.
   Table 2.4.2 lists the categories of economic damages used by several of EPAk 10 regions in
their assessment of environmental problem areas. (Numbers in the cells refer to the EPA region.)
Damages to Materials
   In the context of economic damage assessment, this category includes the soiling, dis-
coloration, erosion, peeling, and cracking of a variety of materials and structures. The eco-
nomic impacts are the costs of repairing or replacing these items. Past comparative risk
studies have identified criteria air pollutants and acid deposition as the primary destroyers
of materials. Specifically, most studies have calculated:
   •  Soiling from suspended particulates
   •  Dye fading from nitrogen dioxide
   •  Damage to rubber tires from ozone
   •  Damage to painted surfaces, metals, monuments, etc., from acid deposition
   This is only a limited set of possible damages. The work group should attempt to iden-.
tify other materials and structures susceptible to damage from pollution.
   One approach to estimating economic impacts from damages to materials has the
advantage of directly incorporating the pollutant concentration in the specific state,

September 1993                         .               .                       2'4'9

 A Guidebook to Comparing Risks ami Setting Environmental Priorities
 often rely on preexisting studies. One approach is to scale national damage estimates
 according to the harvest share of the particular state or region. When using this approach, it
 is important to explicitly state the type of economic damage being discusised in the given
 study. Comprehensive economic studies will address both consumer and producer surplus
 losses caused by yield reductions. Other studies may only address producer losses attribut-
 able to decreased profits or consumer losses attributable to higher prices and/or decreased
 supply. Care should be taken to properly account for bodi  types of damages.          ', :  -
   Variations of the general "scaling" method, as well as alternative methods for assessing
 commercial harvest damages, are considered in trie following subsections on losses to com-
 mercial agriculture, fishing, and forestry.        ,,
 Agricultural Losses                                   .               j
   Agricultural yields for some crops have been adversely affected by different types of air
 pollution. Past comparative risk studies have focused on the agricultural effects of troposr
 pheric ozone (i.e., smog). One approach for calculating harvest losses due to ozone is to use
 preexisting estimates of the percentage reduction in crop yield that follows from a percent-
 age increase in the ozone concentration. Such statistical relationships hav« been calculated
 for a variety of crops and can be located in a number of economic benefits studies (Adams
 et al. 1989, Heck et al. 1983). This relationship can be used in the following fashion:
          Percentage Weld Reduction Per One Percent Increase in Ozone Level ((jt>p Z) r
             Percentage Increment of Ozone from Background Level (EPA 19894)4 x
                State/Region/Country Value for Crop Z Harvest • Producer Leslies
   .This method essentially estimates the decrease iri crop production and multiplies it by
 the per-unit value of the crop. Harvest values are readily available from die U.S.
 Department of Agriculture (or the equivalent agency for foreign countries). Data on ozone
 concentrations are available from state or national air-monitoring programs.
   It should be noted that this method only partly captures the economic: damages, since it"
 addresses only producer losses, not consumer losses. Also, it does not incorporate the
 potential for price changes when agricultural yields are reduced; for example, a decreased
 corn yield may raise the price of corn, mitigating the economic losses experienced by pro-
 ducers. As such, it is an upper bound on producer losses.
   This method is useful because it employs regional ozone data in combination with crop
sensitivity. An alternative, simplified approach that does not rely on ozone data involves
 scaling national damage estimates, using the following general formula:
    Region/State'* Percent of the National Harvest of Crop x National Damage  Estimate for Crop
                            • Total Annual Damage* for Crop
   National crop damage estimates are generally developed on a crop-by-crop  basis so that
the state  or region's share of total production can be obtained by dividing; state/regional
production by national production of a given crop. These statistics can be easily obtained
from the Department of Agriculture (or the equivalent in foreign countries) or even from
the U.S.  Statistical Abstract.
September 1993

                                                           2.4 Quality^of-Life Assessments
   For instance; past studies have calculated dye-fading damages due to nitrogen dioxide
by taking the nationwide damage estimate found in EPA's 1982 Criteria Document and
dividing it by the U.S. population to get per-capita damages. The per-capita figure is then
multiplied by the population of the state or region. Specifically, the following per-capita
damage estimates have been used:
   •  In the 1982 Criteria Document, EPA estimated the per-capita damages from dye
     fading due to nitrogen dioxide to be roughly $1.76 (1988 dollars).
   •  A 1983 EPA study reported that annual damage to tires from ozone was $1.77 per
     vehicle (1990 dollars).                   -
   •  A 1986 EPA study estimated that soiling and discoloration damage to industry from
     suspended particulates amounted to roughly $14.98 per-capita (1988, dollars).
   •  A study by Horst et al. estimated per-capita damages from acid rain to be roughly
     $11 (1988 dollars) (EPA 1986b).
   The per-capita approach has a number of problems. Obviously, it does not incorporate
information on regional pollutant levels. In addition, the studies are often highly uncer-
tain. For example, the National Acid Precipitation Assessment Program contends that the
function relating acid precipitation to paint and mortar damage in the Horst study overes-
timates the actual physical damage. These estimates are provided here only as a rough
guide to the potential magnitude of damages. Rather than rely on these point estimates of
per-capita damage, the analyst should attempt to bracket the damage estimate by either
(1) varying assumptions in the above studies or (2) locating alternative estimates of per-
capita damages.                ,
   Using these methods, past comparative risk studies have frequently estimated large eco-
nomic impacts for damages to materials, particularly for criteria air pollutants and particu-
late matter. Some work groups have viewed the results with skepticism, especially when
the calculations are not based on locally monitored concentrations of pollutants.
Commercial Harvest Losses
 '  A number of air and water pollution problems can cause economic damages by reduc-
ing the yield of commercially produced crops, seafood, and forests. For instance, tropos-
pheric ozone (smog) may impede the growth of certain crop i^ ecies and reduce farm   '
yields. This damages the welfare of both producers and consumers of the commercial
products—producers because of lost profits and consumers because of decreased availabili-
ty of goods and consequent higher prices. Therefore, the most appropriate measure of eco-
nomic damage attributable to decreased harvests is the loss in consumer and producer sur-
plus. In simple terms, consumer surplus is the extra value consumers get  from a purchase
beyond what is actually'paid.3 Producer surplus  represents the revenue that a producer
receives for a good, beyond what it costs to produce the good. In general, it can be
thought of as the profit earned by producers.
   Since measuring lost producer and consumer  surplus requires relatively complex research
into market supply-and-demand conditions, comparative risk economic damage estimates

September 1993                                           ,                 2,4-11

A Guidebook to Comparing Risks and Setting Environmental Priorities
   This method is likely to overestimate producer losses because of a number of simplifica-
tions: First, it measures only producer losses and not potential consumer surplus losses.
Second, it measures lost producer revenue, not lost producer surplus. Furthermore, it
assumes that the amount of shellfish brought to market increases and decreases in propor-
tion to the acreage open to shellfishing; this may not be the case if, for example, shellfish-
ing can be intensified in non-polluted beds without jeopardizing long-term sustainability.
Finally, like the agricultural estimates, this method does not account for price effects; a
decreased catch may raise the price of shellfish, thereby mitigating producer losses.
                             •'',>•         i    •                  - -     -      . • '
   Estimating economic damages due to lost commercial fishing for fin fish is more diffi-
cult than estimating those due to shellfishing.  Designated fishing areas are not as well
defined, making regulation of fishing habits more difficult. Furthermore, the existence of
commercial "hatcheries makes market effects less directly dependent on water quality. Most
comparative risk studies, therefore, tend to rely on preexisting studies that assess economic
costs associated with the pollution of major water bodies in the area.
Commercial Forestry Losses                     ,        .
   The comparative risk study conducted  by EPA's Region IV used two sources to estimate,
damages to commercial forestry. Expert opinion summarized in a 1989 EPA staff paper
suggested .reductions in the rate of forest growsh of between 10 and 20 percent (EPA
1989a). These percentage reductions in timber harvest were applied in simulations of the
U.S. Forest Service's Timber AssessmenfMarket Model, which generated estimates of the
change in consumer and producer surpluses. For example, at a growth reduction of 15
percent, national consumer surplus was reduced by $516 million, while producer surplus
increased by $302 million for softwood and hardwood lumber and by $ 118 million for
softwood and hardwood stumpage (1984  dollars). These national figures were scaled to
Region IV based on forest production statistics,  i
   As with agriculture and fishing, national damage data can also be scaled when calculating
economic damages from reduced growdi in commercial forests. As with agricultural crops,
such damages are usually associated with increased ozone concentrations, although acid pre-
cipitation may affect forest productivity in  relevant areas (e.g., the northeastern United
States). Past comparative risk studies have scaled the estimates in large regional studies. For
instance, Galloway et al. (1986) calculated  consumer and producer losses attributable to
reduced forest productivity in the eastern United States (EPA 1986a). The Region I and III
economic damage studies used these results in conjunction with production information
from state or national forest bulletins to arrive at legion-specific damage figures.
   It is important to note that estimates of forest damages hinge on estimates of the yield
reductions caused by ozone and acid precipitation. The range of expert opinion on this
subject is significant, reflecting the fact that the translation from laboratory impacts to
field impacts is not  well understood. Therefore, the need for an analysis of the range of
possible outcomes should be stressed.;     •-[..-                                   :
Health-Care Costs                          j
   Health-care costs in a comparative risk project are costs 'associated wich the incidence of
environmentally induced illnesses beyond illnessiss that might occur in the absence of the

2.4-14                                      i                       September 1993

                                                            2.4 Quality-of-Lifi Auf
   In the United States, national crop damage estimates have been developed by a number
of researchers, with the most recent figures available from a 1989 EPA study. This study
developed a range.of national damage estimates, recognizing the importance of varying
assumptions about die supply/demand framework in agricultural markets. Specifically,
one set of assumptions assumed no agricultural market distortions due to the structure of
subsidies. Anodiersct of assumptions incorporated subsidies, but allowed for no supply
responses in die form of acreage increases or other adjustments in agricultural policies. A
final set of assumptions calculated the cost savings after accounting for subsidies, but also
allowed for agricultural policy changes. These three different mediods provided duree  .
widely varying estimates of national damage for each crop in the staff paper, leading to
equally wide-ranging regional damage estimates. When possible, die analyst is encouraged
to apply diis type of sensitivity analysis to bracket die range of possible economic impacts.
   Past comparative risk studies have also considered crop losses from sulfur dioxide and
stratospheric ozone depletion using methods similar to those reviewed above. Losses from
diese environmental problems have been found to be minor relative to ground-level ozone
damages, and in the case of ozone depletion, are subject to a greater degree of uncertainty
due to limited scientific data on yield reductions'.  However, ozone depletion may cause
significant future harvest damages (the merits of estimating future damages and calculat-
ing a present value are discussed in Step 4 of diis section). Other environmental problem
areas should be considered for possible contribution to crop loss and should be quantified
where studies are available, or discussed where they are not.
Commercial Fisking and Shellfishing Losses
   Discharges into water bodies from non-point sources of pollution, industrial point
sources, and POTWs (point-of-transfer waste sites) can close off shellfishing in contami-
nated areas. The ideal method for estimating economic damages associated with such
problems would be to evaluate consumer and producer surplus losses. Consumer surplus
would be reduced because a smaller shellfish catch would raise the price of shellfish; pro-
ducer surplus could be reduced because of reduced sales and/or the increased costs of
shellfishing (e.g., boats may have to travel to more distant shellfish beds). However, given
thai the resources for such an assessment are beyond die scope of many comparative risk
projects, producer losses can be approximated using the following equation for die value
of a shellfish catch in a particular area:
                  V« W nf Ae fJifMfliti ratrh in the area under consideration x            .
                       Are* Closed to SheUfuhing - Producer Lotae*
                               AM* Open to SheUfiihing                         '
   This method essentially derives a value per unit of shellfishing area (typically acres) and
multiplies-it by die number of closed acres. Statistics on die status of local shellfish beds
and the value of shellfish harvests are readily available from the National Marine Fisheries
Service in die U.S. Department of the Interior or from the National Oceanic and
Atmospheric Administration. In  foreign countries, data should be available from equiva-
lent agencies. Once total damages are developed, they must dien be apportioned to die
various water pollution problem  areas.

September 1993                             .          .                      2-4-13

 A Guidebook to Comparing Risks and Setting Environmental priorities
 treating the illness, such as medicine, medical appliances, and nursing care. Indirect costs
 reflect the reduced productivity of individuals with the illness—most significantly, fore-
 gone earnings because of time taken offof work. A "human capital" approach is typically
 used to develop per-incident estimates of this fort-gone productivity. For fatal illnesses,
 such as cancer, the human capital approach first calculates what the individual would have
 earned over his lifetime using a discounted present value of estimated mean earnings. This
 is contrasted to the expected lifetime earnings of an individual with the illness, and the
 difference (in present-value terms) represents indirect costs. For less serious illnesses, indi-
 rect  costs are typically measured in terms of restricted-activity days based on mean daily
 earnings. In most cases, indirect costs outweigh direct costs and should, therefore, always
 be considered when determining the costs of illness.  .     '
. - -  •   -                                       i'        ,       ••'•••'.
    Incorporating healdi-care costs into the economic damage assessment may be perceived
 as double-counting the health impacts already covered in the human health section of the
 comparative risk study. However, it is important to recognize the distinction between
 physically enduring an illness and paying for health care. The.rationale behind considering
 health-care costs, is that the economic burden is one that is  borne in addition to the pain
 and suffering of illness.       '              '  !
 Recreational Losses             '
    Since the theoretical nature of recreational damages (and many other damages') makes
 them more difficult to evaluate, .comparative risk economic damage studies frequently rely
 on existing economic studies performed by academic researchers. These studies typically
 follow one of two types of valuation methodologies:                   ;
    •  Revealed-prefcrence studies measure the behavioral relationship between improvement
      in the quality of a recreational (or other) resource and the increased recreational use
      of that resource. This behavioral relationship reflects the use value of the recreational
      resource.                   .  '     '     }        •          '  . ,                •
    •  Contingent-valuation (CV) studies measure willingness to pay for a resource by asking
      respondents to place a dollar value on  improvements in the quality of the resource.
      Depending on how the question is framed, this' approach can measure both use and
      non-use value.5                   •       j
   The CV method uses surveys of experimental settings to elicit individuals' willingness
 to pay for changes in the availability of non-market goods, such as environmental quality.
 Typically, respondents are presented with a contingent, or hypothetical, market where they
 are given information on a particular good and are asked to bid on increases or decreases
 in the supply of the good. Although CV can measure use value, it is used most frequendy
 to identify non-use (intrinsic) values for goods. For instance, we may be confident that
 people have an intrinsic value for the water quality of Lake Huron, even though many of
 diem do not intend to ever use it; simply knowing die lake is clean is of some value to
 them. CV attempts to translate diis "existence value" and other non-use values into  con-
 crete terms. These non-use values are closely related to many of the societal and non-
 quantitative issues currently considered in comparative risk studies.
September 1993

                                                             2.4 Quality-of-Life Assessments
environmental problem. Health-care cost assessments in comparative risk projects have
typically concentrated on medical costs and the cost of lost work time. Indirect costs, pri-
marily reduced productivity due to lost work time, are estimated on the basis of expected
earnings for the time lost from work. The level of analysis can vary from rudimentary to
more sophisticated estimates, depending on project goals and resources.
   Calculation of health-care cost damages relies directly on the estimates of health inci-
dents generated by the health risk portion of the comparative risk study. The basic method
for calculating damages involves multiplying the number of health incidents by the total
health-care costs applicable to that particular illness. For instance, if the health analysis
estimates that indoor radon exposure causes 500 lung cancers per year, this figure is multi-
plied by the medical-care costs for lung cancer ($64,220) to arrive at health-care cost dam-
ages for radon ($32.1 million). High and low estimates of cancer and non-cancer cases can
be used as upper and lower bounds of the economic damage estimate.
                                  Table 2.4J:
             Health Effects and Associated Health-Care Costs (1906 $)
Health Effect
Cancer (i;
Nervous system
Buccal caviiy
Other sites
Giardia (digestive system) (2)
Restricted-activity days (2)
Asthma (2)
Hypertension (3)
Non-fatal heart attack (3)
Non-fatal stroke (3)
Lead exposure, screening (3)
Compensatory education
• (3 years) (3)
Headache (4)
Eye irritation (5)
$ 16,424

- ' 220


$ 48,316



$ 64,740
, 39,796


SOURCES: , * Specific coo* are noc available
Cl)Hirtuoiaal9ll ' .- a»B«howninl98SU«n
(2) Rice 1965 •
(3) EPA 19S5«
(4) HtB 1939
(5) ChMtnotl987
   Table 2.4.3 summarizes the annual health-care costs associated with a variety of cancer
and non-cancer illnesses. As shown, total health-rcare costs include both direct and indirect
costs. Direct costs represent the value of goods and services involved in diagnosing and
September 1993

 A Guidebook to Comparing Risks and Setting Environmental Priorities
 multiplied by estimates of consumer surplus, associated with a fishing day, (as shown in the
 formula below).                               |                     '
    The decrease in consumer surplus due to lost .fishing days is the primary component of
 economic damages due to reduced recreational fishing opportunities. Other components
 are possible, but are more difficult to measure. For example, people who choose to contin-
 ue fishing may seek put new areas to fish. If these areas are more distant than the option
 that has been polluted, the additional travel costs  also may be a part of economic damages.
 Since the methods reviewed here do not capture such damages, they may undervalue the
 total economic impact. If resources are not available to pursue the method outlined in the
 paragraph above, the analyst may wish to consider a less rigorous approach. One alterna-
 tive uses the following equation to calculate damages from a loss in recreational fishing:
                   % of Water Fishable x Annual Number of Fishing Days x
                       WillingneM to Pay Per Fishing Day - Damages
    Like the more detailed method presented above, this equation estimates the increase in -
 recreational fishing days that would result in the absence of water pollution, and then
 multiplies it  by the per-day value of these increased fishing trips (willingmss to pay).  .
 Here, however, fishing days are assumed to  increase proportionally to available fishing
 waters. State 305b reports (or equivalent documents in foreign countries) classify surface
 water according to whether it is boatable, fishable, or swimmable (swimmable being the
 cleanest level). It is suggested that the analyst divide the calculations according to surface
 water type, specifically fresh water and salt water. Past economic damage snidies have used
 the National Survey of Fishing, Hunting, and Wildlife Associated Recreation for data on
 fishing days per  state. A number of academic studies have performed surveys that deter-
 mine the consumer surplus associated with a day of recreational fishing. Although these
 willingness-to-pay figures are highly dependent upon the geographical area and the type of
 fish, figures in Table 2.4.4 are representative of the average consumer surplus per fishing
 day in 1990 dollars.                            !                   '-''•,'
             -          '                '        ['       '              I -,..,'
                                    Table :!.4.4:
                    Willingness to Pay for Recreational Fishing
Type of Fishing
Freshwater Fishing
Saltwater Fishing
Low Estimate
•i ' . .
High Estimate
Source: Walsh 1988
   The estimates in Table 2.4.4 are provided here only to suggest the potential magnitude
of damages. Analysts should attempt to locate willingness-to-pay figures tJiat are specifical-
ly geared to the types of fishing done in the state, region, or country (e.g., fly-fishing, surf-
September 1993

                                                            2.4 Quality-of-LJfi Assessments
   Contingent valuation has been used increasingly by EPA and other organizations to
characterize the more elusive economic benefits of environmental quality. For instance,
EPA is currently sponsoring, a CV survey to evaluate non-use values associated with
ground-water quality. Although CV has played a limited role in past comparative risk
studies (e.g., to value willingness to pay for visibility), methodological improvements and,
increased availability of studies make it more pertinent in future risk-ranking efforts.
However, the method is subject to many criticisms and should, therefore, be used cau-
tiously in policy-making procedures.
   Willingness-to-pay studies based on CV methods are influenced by the knowledge and
values of the  respondents. For this reason, some economists and social scientists believe
they may not accurately estimate the true value of a resource. Where other studies are not
available, however, this method for valuing environmental goods may be useful. It should
be noted that explanations will be necessary during presentations, and some participants
may not be convinced of the validity of the findings. When studies are available, most
analysts prefer to rely on travel costs or other measures of revealed preference to derive
economic damages for non-market goods.               ,                ,
   In general, the results of revealed-preferen^e and CV studies can be combined with
information from state water quality reports (305b reports) to arrive at recreational dam-
age estimates for surface water. Specific approaches are described below for valuing lost
recreational fishing and swimming opportunities. Many other forms of outdoor recreation
exist, and an  attempt should be made to find local studies of recreational activities. In one
case, very significant losses were estimated in an evaluation of lost revenues from beach
closures due to pollution (EPA 1991a). Cost estimates were based on decreases in beach-
use fees and estimates of other expenditures typically associated with beach visits. Where
studies do not exist, a non-quantitative description of possible damages is better than leav-
ing the issue  unaddressed.
Damages to Recreational Fishing
   The Louisiana economic damage assessment presented a relatively complex but theoret-
ically correct approach for valuing damages to recreational fishing. Only a summary
description is provided here; for detailed guidance, the reader should refer to the Louisiana
comparative risk document (1990).
   In general, the method draws on a study by Vaughan and Russell that modeled recre-
ational fishing as a three-step process involving the choices of (1) whether to fish, (2) what
fish species to seek, and (3) how many days to spend fishing. In the first step, Vaughan
and Russell developed a regression equation estimating the probability that a person will
go fishing, given a change in die number of fishable acres in the state or region. This pro-
vides an approach for determining the increase in fishing participation resulting from
improved water quality. In the next step, a second set of regression equations were used to
estimate how this increased participation will be divided between rough (e.g., catfish) and
game (e.g., bass) fishing. A final set of equations allows the user to translate increased par-
ticipation into actual days spent doing each type of fishing. The increase in days can be
September 1993                                                              2.4-17

   A Guidebook to Comparing Risk: and Setting Environmental Priorities
     [(12.262 (VR2 - VR1)) - (0.0647(VR2* VR1'))] * CM - Annual Damages per Household
          where:                                ,      .
          VR2    -  .     annual average visual range: after SO reduction (km)
          VR1    .       annual average visual range before SO reduction (km)
          CPI    -       consumer price index, all Items, wage earners and clerical workers
     The coefficients in this model were developed by incorporating the results of five sepa-
  rate contingent-valuation studies of visibility. It may be useful to vary the assumptions on
  which the coefficients are based (e.g., vary the mix of contingent-valuation studies) to
  develop a range of damages per household (EPA 1988a, 1988c).7
     The baseline visual ranges in the visibility benefits equation can be obtained using
  models in the sulfur oxide RIA that relate emissions to visibility, or from other sources,
  such as state air office data. The average annual visual ranges after SO reduction can be
  calculated by using the emission reduction models in the RIA or by assuming lower- and
  upper-bound visibility improvements (e.g., a lower bound of 5 percent improvement and
  an upper bound of 20 percent improvement over baseline).8                '
    Once the visibility damages per household have been estimated, the toical damages can
  be obtained by simply multiplying the.per-household damages by the number of house-
  holds in the .state,  region, or country. Due to the natural Variation in visibility from one
  geographic area to the next, it may be best to perform the calculations on a state-by-state
  basis and sum the  results to the regional level, if a regional study is being'performed.
  Similarly,  if a national study is being performed, calculations should be done on regional
  levels, and the effects summed to the national level.
    The  model described above is appropriate for valuing visibility in most geographic
 areas. However, certain states, regions, and countries may contain areas that inspire a
 greater willingness  to pay for visibility. Visibility benefits for these areas can be calculated
 using the willingness-to-pay equation per vehicle trip per year provided below:            .
       Willingness to Pay for Visibility Per Vehicle-Trip Per Year x (VR2 - VR1) VeMcle Trips
                           Per Year • Annual Viability Damages
         where:           •                     •  !               '..      • •.  ..
         VR2    .       background visual range (km)
         VR1     .       annual average current visual range (km)
   A number of willingness-to-pay studies have been  conducted for national parks. These
studies provide estimates of willingness to pay per vehicle mile per kilometer of visibility
improvement. One study used in previous economic damage assessments estimates that
willingness to pay for improved visibility at Mesa Verde National  Park ranges from $0.02
to $0.04 (1990 dollars) per kilometer of visibility improvement (EPA 1990b). Vehicle
trips per year can be calculated as the number of people visiting the Class I areas divided
by the average number of people per vehicle (roughly 2.5). Data on numbers of people
2>4"20                                                              September 1993

                                                            2.4 Quality^of-Ufi Assessments
casting), as well as to the type offish being sought and the geographical surroundings that
affect the fishing experience. It is best to identify a range of willingness-to-pay estimates to
bracket the overall damage estimate.                                          "
Damages to Recreational Swimming       '         .          •
   Methods for estimating economic damages associated with lost swimming opportuni-
ties are very similar to those used for recreational fishing. In theory, the primary compo-
nent of damages is the reduced number of days that will be spent swimming and the asso-
ciated loss in consumer surplus.6 The second method discussed above (the unit day value
method) can also  be used in the following fashion to estimate swimming losses:
                % of Water Swimmable z Annual Number of Swimming Days z
                     Willingness-to-Pay Per Swimming Day • Damage*
   The following sources can be used in these calculations and can be combined to deter-
mine damages due to reduced swimming opportunities.
   •  Saltwater swimming days may be estimated using the following equation (EPA
     Population 'Within Coastal Area z Proportion of Population That Participates in Swimming
                  z Number of Trips Per Person Per Year • Swimming Days
   •  Based on several studies, Walsh et al. (1988) estimated average consumer surplus per
      swimming day to be roughly $25 (1990 dollars). Estimates vary, however, and the
      analyst should attempt to locate studies geared to the state, region, or country in
   •  In the United States, state 305(b) reports can be used to determine the percent of
     water not swimmable.
Aesthetic and Visibility Damages
   Aesthetic damages typically include odors, noise,  reduced visibility, and unpleasant
visual elements, such as litter. Willingness-tcnpay studies and travel costs may be used to
estimate losses. Among the costs factored in are losses to the tourism industry arid sup-
porting industries, such as hotels, restaurants, and car rental companies. Decreases in
property values due to degraded aesthetic conditions may also be considered.
Visibility Damages
   Economic damages from reduced visibility are typically associated with sulfur oxide
(SO)  emissions. Several EPA studies (Regions I, IV, and VI) have applied a model devel-
oped by EPAs Office of Air and Radiation to estimate these damages. The model esti-
mates the annual visibility benefits associated with achieving various air quality standards
for sulfur oxide emissions. These benefits are equal to the damages that are present due to
existing sulfur oxide levels. Visibility benefits per household are estimated using the fol-
lowing equation:
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
applied in these analyses typically involves using academic studies of homeowners' willing-
ness to pay to increase the distance between their homes and the waste sites. Three studies
have been used to bracket damage estimates:     i
   • Michaels et al. (1990) found that homeowners were willing to pay $86 to $838
     (1986 dollars) per mile from uncontrolled hazardous waste sites  in Boston.
   • Smith and Desvouges (1986) found a willingness to pay of $330 to $495 (1984 dol-
     lars) for each mile from a hazardous waste kndfill.                     .
   • McClelland et al. (1989)  found average home prices to be $4,800 (1988 dollars)
     lower when residents expressed concern about a nearby Superfund site.,   ;
   These estimates of damage per home are used in the following equation:         .     ,
   Number of Sites (e.g., Superfund, municipal solid waste) x Average Residences Within One Mile
            x Willingness to Pay to Avoid Living Wittiin One Mile » Annual Damages
   Past comparative risk studies have varied in their approach to estimating the number
of residences within one mile of Superfund sites, RCRA facilities, municipal landfills,
and other waste management sites.9 One simple method is to calculate the average popu-
lation density per square mile in .the state, region, or country (population divided by land.
area in miles) and divide it by the average number of people per home; this provides a
rough estimate of the number of homes within one mile of each site.  Since the popula-
tion density around wvaste sites may be significantly different from the average (e.g.,
Superfund sites may be in urban areas, municipal, landfills in rural areas), a more detailed
approach may.be beneficial.                   !                               ;
                                             i         • '  .
   The analyst should bear in mind two significant uncertainties when using these proper-
ty damage methods. First, the willingness-to-pay studies that are available apply to either
Superfund or RCRA waste sites. It may not be appropriate to use these willingness-to-pay
figures to estimate damages from municipal solid waste sites; however, studies specifically
geared to municipal landfills, are not currently available. Second, the willingness-to-pay
studies actually estimated damages for each mile added to the distance from the site. The
studies do not provide concrete guidance on how this effect decreases with successive miles
from the site—e.g., residents 10 miles from the  site should not be willing to pay 10 times
what they would pay to be one mile from the site. The method described above may
underestimate damages, since it only calculates damages based on homes less than one
mile from the site.                             i"       .       ,---.•.
Resource-Restoration  Costs                   j
   Society incurs economic costs when actions must be taken to restore a resource that has
been contaminated due to residual pollution. For example, if a household's drinking-water
supply is contaminated, the homeowner may have to pay to dig a new well. Resource-
restoration costs are disoissed separately from the direct-damage estimation methods
because their use.raises  a number of potential problems. First, resource-restoration costs
have the potential to double-count direct damages. For example, expenditures to reduce
radon concentrations will prevent adverse health effects. As a result, the comparative risk
                                             j. .    .          >             .

2.4-22                                               .              September 1993

                                                           •2.4 Quality-of-Lifc Assessments,
visiting most Class I areas are available from the National Park Service (or the equivalent
in foreign countries).                                      .              "
Other Aesthetic Effects
   Aside from damages associated with reduced visibility, very few other aesthetic damages
have been directly addressed in past economic damage studies. These damages area not
necessarily excluded form the economic effects analysis, however, since property damage
estimates are likely to reflect the aesthetic conditions near the house.
   Some comparative risk studies have estimated aesthetic damages by drawing on a num-
ber of EPA benefits studies that have found aesthetic damages to be equal to some fixed
percentage of recreational damages when considering surface-water pollution. For exam-
ple, the Region I economic damage study estimated aesthetic damages for surface-water
pollution problems to be between 40 and 70 percent of the recreational damages; howev-
er, this approach is very simplistic. Analyzing reductions in property value is a theoretically
sound method for capturing the economic effects of aesthetic degradation (see below), but
it also tends to capture other damages as well. As demonstrated in the Vermont compara-
tive risk study, a non-quantitative treatment of the social damage posed by aesthetic degra-
dation may represent a more effective alternative.
Property-Vfclue Losses                                      .
   One alternative  measure of economic damage is the reduction in the value of property
located near areas of potential environmental risk. For example, a house located near a
hazardous waste landfill may experience a reduction in value that may or may not be real-
ized in the market, depending upon whether the house is sold. Economic damage still
occurs, however, even if the damage is unrealized.
   In general, property-value losses may reflect health, aesthetic, recreational, or other
damages that are already addressed in other components of the economic effects study.
Because of the potential for double counting damages covered elsewhere in the economic
effects assessment,  it is important to be aware of what damages are actually being captured
by a reduction in property values. A nearby hazardous waste landfill  may cause home val-
ues to drop because of the threat of ground-water contamination and subsequent drink-
ing-water exposure. Property values also may drop because of aesthetic impacts, such as
odors or the unpleasant appearance of the facility. The facility may pollute a nearby pond,
reducing recreational opportunities, such as fishing or swimming. Therefore, while prop-
erty-damage estimates may add valuable information to the overall characterization of eco-
nomic impacts, they should be used carefully. In particular, two uses are appropriate:
   1. Calculating property damages for environmental problems where no alternative
     methods exist for measuring damages.
   2. Properly coordinating property-damage estimates with other types of damage esti-
     mates (e.g., using them as an upper bound for damages attributable to a particular
     environmental problem).
   In past comparative risk studies, property damages have been estimated for Superfitnd
sites, RCRA hazardous waste management sites, and municipal landfills. The method

September 1993                                                            2.^-21

 A Guidebook to Comparing Risks and Setting Environmental Priorities
   Past comparative risk studies have used"! variety of estimates of the cost of remediating
 contamination of private and public (municipal) water supplies. Private wells can be reme-
 diated in the following ways:.                  \                     i           ,.       .
                                             i        , •           "''      •      .
   ,•  Each affected household can apply point-of-use treatment to purify contaminated
      water and make it suitable for consumption. Total capital costs range from $1,000 to
      $5,000, and annual operating and mainten«ince costs are between about $500 and
      $ 1,000 per year, depending on the degree of contamination (EPA 1991 b).
   •  Supplies can be replaced by extending a hookup from a municipal system, costing
      between $2,300 and $17,500 (capital costs): per household, depending on the dis-    ,
      tance from the nearest existing municipal supply and the number of wells being
      replaced.                       .         |   '               .   :-
   •  Private wells can also be replaced by digging a new well. The cost for a new well
      varies greatly, depending on the depth to ground water and other geological factors.
      Past comparative risk studies have used capital cost estimates of between $3,500 and
      $7,500. This is consistent with models developed by EPA, which indicate that capi-
      tal costs for a new private well are roughly, $5,000, with annual operating costs of
      about $200 (EPA 1988b).             '   !
                                          t • J                    • "           '        ; •  j
   The analyst will need to take into account the specific conditions in the area t,o deter-
 mine the remediation approach most appropriate for estimating damages to private wells.
   Because of their size, municipal wells are mudi more costly to remediate than private                         }
 wells. The following approaches are possible:     ';
                                             i ,  •      .     .      .      • ''         .        '
   •   Treatment of municipal wells is one option. Total capital and operating costs range
      widely, depending on the treatment method, the type of contamination, and the size
      of the water supply system. Existing EPA models estimate that for a system serving
      2,000 people,  total capital and operating costs are between about $360,000 and $1.2
      million, respectively (EPA 1989b, 1989c).u               ,'.'..'
   •   The cost of replacing a municipal drinking-water supply is also subject to uncertain-
      ty. Existing EPA models  estimate that a full municipal system serving 2,000 people
      has a capital cost of about $6 million, plus annual operating costs oif about $41,000;
      (EPA 1988c). However, if the distribution main (or prJier equipment)  from the orig-
      inal system is used, costs will be much lower; previous studies used vhc range
      $150,000 to $315,000.                   i
.  •       •      .          .                    i  ' ' '.              • •  '          •     '•
   Total damages can be estimated by combining figures such as these with the number of
wells contaminated for each problem area.       |            •
Mitigation of Radon in Homes                   i                     i                            '
   Most economic damage studies have estimated riie cost of preventing exposure to ele-
vated levels of radon in homes. The following equation can be used for radon abate-
ment costs:                          .         j                               '•'•',                     ,
            Average Co*t of Remediation x Number of Homes With Elevated Radkm r
                          % of Home* Remediated • Damage*                                                 \
September 1993

                                                            2. 4l Quality-of-Lifi Assessments
 analyst must ensure that the assessment counts either health effects or resource restoration
 costs, but not both.
   A second, more fundamental problem with resource-restoration costs relates to the
 uncertain relationship between such costs and actual economic damages. In the past,
'comparative risk work groups have been tempted to use potential total remediation costs
 as a measure of the damages attributable to an environmental problem. However, this
 approach is incorrect because there is no simple association between the costs of cleaning
 up a problem and the societal benefits that are realized by eliminating the pollution.
 They often reflect the requirements of environmental legislation, rather than actual dam-
 ages. For instance, it may cost $1 million to remediate a contaminated aquifer through
 pump-and-treat methods. If this is a remote, non-potable aquifer, the current'economic
 benefits realized after the cleanup may be minimal. In this instance, the cleanup costs are
 a poor measure of the potential benefits that would be realized (i.e., the currendy  •
 incurred damages).
   The following section presents methods for estimating two types of resource restoration
 costs: (1) the costs of restoring drinking-water supplies in cases of well contamination and
 (2) the costs of mitigating radon exposure injiomes.
 Restoration of Drinking-Water Supplies   ,
   Other restoration costs that have been estimated in past economic damage studies
 include remediating drinking-water supplies and removing asbestos and lead paint. The
 basic formula for estimating the costs  of replacing contaminated drinking-water supplies is:
        ' Number of Wells Remediated Annually x Cost of Replacing or Treating Each Well -
                    Capital Cost of Replacing Contaminated Water Supply
   The assessment should focus on the number of wells remediated each year, as opposed
 to the number of wells contaminated. For example, in the Region VI economic damage
 assessment, the numbers of wells remediated were only a small fraction of those actually
   Because data on the number of wells remediated sometimes are difficult to find, past
 studies have relied on the expert opinion of regional personnel. In some cases, the number
 of contaminated wells has been used to compute an upper-bound cost. The number of
 contaminated wells associated with each problem area may be available from regional
 reports or data bases.10 For instance, a data base-supplied by the Region I Water Supply
 Office provided information on the types of water-supplies contaminated and the source
 of the contamination (underground storage tanks, municipal landfills, and other sources).
 For Superfund sites, Region I's Site Information Tracking Effort data base was used. In
 Region IV, a survey of 34 Superfund sites found that roughly 2 percent of the sites conta-
 minated drinking wells each yean this figure was used to extrapolate to the universe of
 Superfund sites in the region. In general, each state, region, or country will individually
 need to research the number of wells  remediated and/or contaminated, since data sources
 will vary.
 September 1993                                                            2.4-23

  A Guidebook to Comparing Risks and Setting Environmental 'Priorities
  materials (PVC plastics), increase health-care costs, and reduce commercial harvests. The
  "snapshot" method that analyzes only present damages would place ozone depletion at or
  near the bottom of the economic damages ranking, This approach would mask the impor-
  tance of the ozone depletion issue.              !      '••""•'    .1
    There arc two solutions to the problem of increasing risk over time. One solution
  would be to extend the time horizon when assessing damages for all the problems on the
  comparative risk list. For example, damages could be discounted over 100 years to obtain
  a present value for damages for each issue. This approach has been avoided because of the
  complexity involved in forecasting damages far into the future, which would require ana-
  lytic approaches well beyond the means of the comparative risk studies.
    A second approach provides a less rigorous but more practical solution by considering
  annual damages occurring in different future years and discounting them to the present.
 This discounting places the annual damage estimates back on a par with the other annual
 estimates in the study, providing a consistent basis for the ranking process. Since this
 approach need only be taken with the limited number of environmental problems that
 have increasing long-term effects, it does not require substantial additional resources.
    Estimating damages to commercial harvests from ozone depletion illustrates the general
 method for discounting future damages. The scientific literature does not: provide defini-
 tive information on the impact of UV-B radiation on plants, so past economic damages
 studies have relied on a large range of potential yield reductions (EPA/UN 1986) A lower
 bound of no effect on yield has been combined with an upper bound of si 20 percent
 reduction in yield in past studies. This yield reduction can be multiplied by the current
 annual value of the crop in the state or region to determine actual crop damages.
   To show that current risks from UV-B radiation are limited but will increase over time,
 it has been assumed that the 20 percent yield reduction will occur 100 years from now (in
 the year 2093). Present damage can be set to 1 percent of this future level and can be
 increased linearly over time by 1 percentage point each year.12 For example, if the 20 per-
 cent yield reduction is expected to cause $300  million in damages in year 100, the damage
 in year one would be $3 million (1 percent of $300 million), the damage in year two
 would be $6 million (2 percent of $300 million), and so on. This calculation provides
 estimates of the annual harvest damages dial will occur  in various years in the future.
 These figures can simply be discounted back to the present and used as an estimate of cur-
 rent annual damages! The following equation summarizes this present-value calculation
 for this example:                               j
                        S3 million 4. M million <........ S3QO mi1Hr.n    ,     -
where ; is the interest rate used to discount future effects. If desired, this present value can
then be placed on a rough annual basis by dividing by 1 00 years or by some other annual-
ization approach (e.g., multiplying by an interest rate).
                                                                   September 1993

                                                          2.4 Quality^of-Life Ajseu?jifnts
   When applying this method, the assumption is that different remediation techniques
will be used at different radon concentrations. Past studies have divided radon concentra-
tions into three ranges — less djan 4 pCi/L, 4 to 20 pCi/L, and greater dian 20 pCi/L.
Concentrations over 4 pCi/L are generally considered to be of concern. In the United
States, state-by-state data on the distribution of homes into these categories are available
from surveys conducted by EPA's Office of Air and Radiation.
   Once the distribution of radon concentrations in homes is known, the number of
homes that remediate for radon must be estimated. While information on remediation
rates is greatly lacking, studies have considered the percentage of homes tested in combi-
nation with the percentage of homes that remediate once elevated levels are detected. One
source estimates that less than 5 percent of U.S. homeowners have tested for radon (Oge
1990). Contacts with radon testing and mitigation firms indicate that less than 10 percent
of homes with elevated radon (greater than 4 pCi/L) are remediated. This  suggests an
overall remediation rate of 0.5 percent for homes with elevated radon.
   As mentioned, the cost of remediation is assumed to vary widi the radon concentra-
tion. The following cost figures, drawn from the EPA document Radon Reduction
Methods: A Homeowner's Guide (EPA  1 987) have been applied in past studies:
   •  For homes with radon concentrations between 4 and 20 pCi/L, remediation typical-
     ly consists of sealing cracks and  holes in the walls and floors  of basements, at a cost
     •of approximately $100 per home (1988 dollars).
   •  For homes with radon concentrations above 20 pCi/L, remediation may involve slab
     suction, air-to-heat exchange, or other ventilation systems that have an average cost
     of approximately $2,500 per home (1988 dollars).

   The data arc analyzed quantitatively to provide an estimate of die relative severity of
impacts from each problem area and the number of people affected. Wherever possible^
non-quantitative information is added to the description of the problem area. Consistent use
of criteria and analytic techniques is important to the credibility of die assessment process.
   To fully characterize economic damages, it is sometimes necessary to consider effects
well beyond the immediate time frame and outside the traditional arena of econprnic valu-
ation. Examples include long-term/increasing-risk problems, such as the effects of global
warming, ozone depletion, and diminishing species diversity, and  the economic valuation
of complex ecosystems. Applying a defensible discount rate is a problem associated with
assessing risks over a long time frame.                                 „

Long-Term Damages
   The need for temporal adjustments to the economic damage assessment is Best illustrat-
ed by an example. Although ozone depletion does not currently pose large economic dam-
ages, the problem is expected to escalate over time as the ozone layer is further damaged
and as increased UV-B radiation reaches the earth., This radiation is likely to damage
September 1993  '

X Guidebook to Comparing Risks and Setting Environmental Priorities
   Quantitative and non-quantitative information is presented in written descriptions of
each problem area and in charts, matrices, and other tools for comparison. A group of*
project participants, usually the quality-of-life work group or a policy-level committee
advised by the work group, uses the information presented to develop a relative ranking of
environmental problem areas for quality-of-life issues.
   It is important to document the process and methods used in a comparative risk project.
This is particularly true for quality-of-life issues, which may require controversial analytic
methods or may involve values that are not universally shared. A dear statement of sources,
quality, and extent of data, methods used, assumptions made, and degree of uncertainty in
results will add to the credibility of assessments. Differing views and core values need to be
clarified, respected, and addressed. Where expert opinion is used in the absence of data, it
should be clearly stated. These elements should be explained briefly in an isverview that can
be understood by non-economists. Decisions should be made regarding how to explain the
often controversial results and analytic methods of the quality-of-life assessment.

Establishing an Integrated Ranking     \
   Quantitative elements of quality-of-life impacts can be presented side by side with non-
quantitative descriptions of impacts that are less amenable to unit measurement. In fact,
scoring methods like those described in this section have been developed to combine non-
quantitative factors with dollar damage estimates (EPA 1990c).13
   One approach in establishing an integrated ranking is to translate the non-quantitative
information into a numerical form more consistent with the dollar damage estimates.
Table 2.4.5 shows how one EPA region accomplished this. In the.first step, a "high,"
"medium," or "low" label is established for each factor across problem areas.  Next, a score
is attached to these labels; for instance, the "highs" can be given a score of 10, the "medi-
ums" a score of 5, and the "lows" a score of 1. Then, these scores can be added to obtain a
total score, or each factor may be weighted according to the importance attached to it by
the work group (as seen in Exhibit 2.4.4). This refinement allows certain factors to influ-
ence the final score more than less important ones.                               '
   The final step in this approach is to merge the non-quantitative score with the dollar
damage estimates. Since  the objective is simply an ordinal ranking of issues, this can be
accomplished in a variety of ways. One approach would be to convert the dollar damage
estimates into scores on a scale (e.g., a scale from one to five) or into "high," "medium,"
and "low" labels: Another approach would be to adjust the dollar damages upward when
there are non-quantitative impacts for the problem area (EPA 1988c). A third approach
would be to evaluate and rank problem areas in terms that best suit that problem rather
than trying to convert all the information into a common metric Each quality-of-life
work group must decide for itself which approach it is most comfortable 'with. Exhibit
2.4.4 provides a synopsis of the quality-of-life problem-area analysis and ranking process
used in the Louisiana Comparative Risk Evaluation (1991b).
September 1993

                                                             2.4 QuttUiy-of-Life Assessments
 Discount Rate
    The discount rate used in this sort of present-value calculation reflects important policy
 assumptions. Higher discount rates (6 to  10 percent) suggest that future effects are signifi-
 cantly less important than current effects. Lower discount rates (1 to 5 percent) imply that
 damages imposed on future generations are only slightly less important than those occur-
 ring now. A discount rate of zero would eliminate devaluation  of future effects. The eco-
 nomic damages work group should carefully determine what discount rate is appropriate.
 Analysts should review the literature on the use of discount rates in natural resource eco-
 nomics and consider performing sensitivity analyses diat incorporate different, discount
 rates (JEEM 1990).          .
    Methods of this  type can be used to calculate a number of categories of damage, includ-
 ing materials damage due to ozone depletion, and harvest damages, aesthetic damages,
 and damages from sea level rise due,to global warming. This approach is very simplistic,
 since it ignores important factors, such as changes in the value  of resources as they become
 more scarce. One alternative method is  to explain the factors involved in future values and
 use an innovative presentation format to convey the importance of temporal issues. For
 example, one report has suggested arranging all economic effects  in a matrix that non-
 quantitativcly describes the recovery time  for the resource in question (EPA 1990a).

 Services From Ecosystems
   The services provided by complex ecosystems include a range of important functions
 that, while extremely valuable to humans, frequently go unrecognized in the economic
 damage assessment. Recent studies performed for EPA have compiled existing analyses
 and have begun to establish methods for valuing certain sensitive ecosystems. One study
 presents an overview of services provided by wetlands and summarizes the economic
 methods used to value wetlands (EPA 1991d). While no one method yields an estimate of
 the value of all the services provided by wetlands, the report suggests that the total value of
•an acre of wetlands  is in the range of $5,000 to $15,000. Another study prepared for EPA
 considers the value of forest ecosystems in the southeastern United States (EPA 1991 c). In
 addition to market-based services considered in this section (e.g.,  recreation, timber pro-
duction), the study  examines the value of forest services, such as erosion control and flood
control. For example, to estimate the damages caused by soil erosion, the report  considers
 the costs associated with increased sedimentation of surface water (e.g., dredging costs).
   Valuation methods such as these may be useful in future comparative risk studies,
where economic damages attributable to physical degradation of terrestrial and aquatic
habitats could be projected based on estimates of lost acreage and estimates of value per
acre for the habitat.  Where economic valuation is not feasible, damages to complex ecosys-
tems can be incorporated in the consideration of social costs (as in the Vermont  compara-
tive risk analysis), pr in terms of non-quantitative adjustments to the ddllar-based ranking:
September 1993                                                            2.4-27

A Guidebook to Comparing Risks and Setting Environmental Priorities
                                            Exhibit 2.4.4:
                           Louisiana's Quality-of-Life Ranking Process
     Orientation                                                                                   *
     The work group was introduced to the EPA method of quality of life impact assessment during a two-day
     orientation for the Technical Committee in March 1990. Before ranking the problem areas, the group met
     nine times between April and December 1990.           ;                  .                 -

     Full List of Issues Chosen
     The group began, as did all three work groups, by identifying the list of issues that the entire Technical
     Committee would examine-                            ;

     Familiarization with Economic Analysis
     In the Quality of Life work group, members did not assume sole responsibility for individual issue
     analysis, as was done in the  Health and Ecology Work groups. Instead, the group met regularly with a
     consultant to become familiar with each of the damage categories for which he prepared an economic
     assessment                         ,                 ;            .

     Supplementing The Economic Considerations '       i
     In addition to the quantitative analysis performed, the Quality of Life work group decided to include
     several other kinds of losses in its ranking of issues.      j               '
                                                        i                           i        f
     Weighting Economic Analyses and Qualitative Work  ;                    '
     The work group members considered at some length how to reconcile the quantitative information
     compiled by Dr. Farber with their qualitative assessment. The group was very uncomfortable with the
     quantitative information, because it was so incomplete for so many issues in which Hole or no data exist to
     associate costs to the losses society incurs as a result of these issues.

     There is a significant amount of data in some areas. For example, many studies have been done estimating
     the cost of fishing and boating losses when water bodies have been closed because they do not meet the
     standard for these uses.  However, no parallel studies have Ibeen conducted to determine tine cost of lost
     opportunities to exercise when the air is so unhealthy that people cannot exercise. •

     It may not .even be possible to associate costs with such losses. For example, does Louisi ana suffer losses
     in tourism and new businesses locating here as a result of the publicity the stale receives from its high
     ranking on the toxics discharge to the environment list?   |

     The work group agreed to treat the overall value of the economic analyses as equivalent to the qualitative
     work. Therefore, the group decided to organize economic analyses into five levels, high to low, based on
     dollar values. The work group was then able to rate each issue according to six factors. It established
     weights for the different ratings (low=l t high=5), and the support staff then calculated rankings.

     Alternative Ranking Schemes
     The support staff provided four alternative ways to calculate rankings, by varying the weights attributed to
     the qualitative aspects. The work group examined the results produced by the four alternative ranking
     schemes,  -   ,                      •                 ;                         .       '

     Preliminary Ranking                                <
     The group decided to have four levels of priority in its ranking. Any issue that consistently remained in the
     same priority ranking across the four alternative schemes was ranked in that category.

     Final Ranking
     The work group's discussions focused on issues that received a different ranking, depending on the scheme
     used.     '         '                   '      -'.I'-                        i,  -      '
September 1993

                                                                    2.4 Quality-of-Lift Assessments
Table 2.4.S:
EPA Region I Presentation of Results
Problem Area
Criteria Air Pollutants
Acid Deposition
Hazardous Air Pollutants
Indoor Radon
Indoor Air Pollutants '
Industrial Point Sources
(Rivers and Streams)
Industrial Point Sources
(Lakes and Ponds)
Industrial Point Sources
(Oceans. Coasts, Estuaries)
Municipal Point Sources
(Rivers and Streams)
Municipal Point Sources
(Lakes and Ponds)
Municipal Point Sources
(Oceans, Coasts, Estuaries)
Non-point Sources
(Riven and Streams)
Non-point Sources
(Lakes and Ponds)
Non-pouil Sources
(Oceans, Coasts, Estuaries)
Drinking Water
RCRA Waste Sites
Superftmd Waste Sites
Municipal Waste Sites
Industrial Waste Sites •
Accidental Chem. Releases
Storage Tank Releases
Ground-Water Releases
Pesticide Residue and
Environmental Lead
# of Peopl
. Medium
tion Effect
Low ,
of Substitute
High '
• Medium
of Effects
retical Cost:
' Low
Medium •
High ,••


.Total Scor
1.9 .
• 7.1
. 4.7
9.1 .
9.1 ,
                                                                                               * Dollar ditni{6 estimates in millions.
        Weighting Factors:

      Number of People  » 0.05
      Effects on Subpop.= 0.30
      Substitutes        = 0.05
      Reversibility      - 0.05
      Costs             = 0.15
      Uncertainty/Bias   = 0.40

      Sum of Weights:   = 1.00
                                      KEY TO RANKING CRITERIA
Scoring Factors:
  High   =10
  Medium = 5
  Low    = 1
Example of how to calculate weighted total score
for Criteria Air Pollutants:

(10 x 0.05) + (10 x. 0.30) + (10 x 0.05) + (1 x 0-05)
+ (1 x 0.15) + (1 x 0.40) = 4.6
September 1993

A Guidebook to Comparing Risks anASetting Environmental Priori ties
                                         Table  2.4.7:
                          Louisiana Quaiity-of-Life Damages Matrix
Problem 'Areas
IndusL Waste- Water Discharge
Music. Waste-Water Discharge
Drinking Water Supplies
Non-point Sources
Loss of Coastal Wetlands
Loss of Inland Wetlands
Ground- Water Contamination
Storage Facilities
. RCRA Hazardous Waste Sites
Superfund Hiz. Waste Sites
Munic. Solid Waste Sites
Indust Solid Waste Sites
Accidental Chemical Releases
Sulfur Oxide*
Ozone, Nitric Oxides, and.
Carbon Monoxide
Airborne Lead
Paniculate Matter
Indoor Air Pollution
Naturally Occurring Radon
Terrestrial Habitat Loss
Strat Ozone Depletion
Global Warming/COi
Deep- Well Injection
Flcodplain Development
Natural Resources
'Oil & Gas Wastes
Worker Exposure
Seafood Contamination
Consumer Exposure
Number of
• Low

of Effocu
High .

. Low
• High
blllty of

biuty or


Loiwf '
. —

— ,
       Based on the information available from an economist and the work group's best professional judg-
       ment, each problem area was rated as high, medium., or low, as it related to the following factors:
       Number of People Affected — This parameter accounts for the percent of the state's population affect-
       ed by the damages .associated with the problem area—-for example, people who can no longer swim in
       water posted by die state as unsafe. The following guidelines were applied to rank the problem areas:
          High              More than 1  million people affected (23% of LA population)
          Medium          10,000 to 1,000,000 affected (0.2% - 23%)
          Low              Lew than 10,000 affected (0.2%)
       Severity of Effects on Subpopulations — This parameter is a measure of the extent to which the issue
       imposes damages on subpopulations. For example, if oyster beds are closed due to contamination, then
       those -who make their living catching oysters would be a subpopulation that disproportionately suffers
       from this problem.                      •    •  .
          High              Significant impact on lubpopulation
          Medium          Moderate impact on jubpopulation
          Low              Loir or no impact on lubpopulation
September 1993

                                                            2.~4 Quality-of-Lift Aistuments
Summary Tables
   Another basic presentation tool is a summary table that gathers together relevant infor-
mation on economic damages. Table 2.4.6 provides the midpoint of the range of estimated
dollar damages, as well as the weighted total scores. Adding a comments column would
allow the analyst to communicate the major uncertainties in  the estimates and the biases
these uncertainties may introduce.
                                  Table 2.4.6:
                            Sample Summary Table
Problem Area
Storage Tanks
Indoor Radon
Primarily cost to remediate
drinking water, upward bias
due to uncertainty about #
of wells requiring replace-
Primarily health-care costs.
   The Louisiana Comparative Risk Projeet*(1991a) was conducted as the basis for the
Louisiana Environmental Action Plan, LEAP to 2000. It included a quality-of-life damage
category for "unmonetized damages" to supplement quantitative assessments of monetized
damages. Some of the non-quantitative damage categories could theoretically be quanti-
fied, but little or no data were available. Table 2.4.7 illustrates categories of economic and
social impacts evaluated by participants in the Louisiana project.
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
 .  •   Taxes and user fees. To a certain extent, taxes and user fees determine the behavior of
  •   individuals and industries in an area. For example, a relatively high fee for water may
     discourage excessive use, and a significant tax on gas guzzlers may encourage people
     to buy more efficient automobiles. Surface-water, ground-water, and air pollutio'n
     are among the problem areas that could be affected. A future-oriented assessment of
     environmental problem areas should consider the consequences incentives of this
     kind might have for the quality of life.     j                                    .
   •  Judicial and enforcement systems. Enforcement systems currently in place may also
     affect the level to which a problem is presently controlled. If those systems were
     removed, certain environmental problem areas might degrade andcould have nega-
     tive impacts on the quality of life.         ;
   •  Regional needs for energy, water, and sewer services. Population and  economic trends
     affect the future needs of a community for water treatment, energy generation, and
     sewerage. Salinization of soils and water bodies, combined sewer overflows,  and
     power  plant emissions are among the problem  areas that might have increased
     impacts on the quality of life.             |
   Several comparative risk projects have discussed the question of how to include a
longer-term  viewpoint in their assessment of environmental problem areas to capture
increases or decreases in risk over time. For example, EPA Region IV incorporated esti-
mates of future demographic, transportation, and  industrial trends in its comparative risk
analysis (EPA 1992). Issues likely to change over time are often discussed! generally in non-
quantitative  descriptions of the problem areas. While a more rigorous analysis can add an
important dimension to the assessment, quantitative models designed to add a temporal
dimension to the analysis may involve many assumptions, some of which may be cpntro- •
versial. Section 2.1 of this document discusses general analytical issues including problem
area changes over time.                                                   .
September 1993

                                                                 2.4 QuaJity-of-Lifr Assessments
      Availability of Substitutes — This parameter measures the extent to which substitutes are available to  ,
      replace the quality-of-life losses associated with the issue. For example, if a water body is closed to
      swimming, is another water body available nearby that people would use as a substitute?
         High            No substitutes are available
         Medium         Some substitutes are available
         Low             Substitutes are readily available

      Reversibility of Effects — This parameter is a measure of the degree to which the damage caused by an
      issue is reversible over a short period of time. For example, runners might decide not to run on a day
      when ozone levels are high, but could run again as soon as the ozone returned to a healthy level. In con-
      trast, wetland loss is irreversible. Louisianans will never again be able to birdwatch in the lost wedands.

         High            Irreversible'
         Medium         Fully reversible after 10 years
         Low             Reversible within 10 yean

      Unaccounted Damages — The work group developed this category to capture any losses that were not
      considered under die economist's analysis. This category also includes die impacts for which the econo-
      mist could not develop an estimate. The work group brainstormed during die enure first day of their
      ranking retreat and listed out all aspects they believed .relevant. The work group did not identify objec-
      tive criteria to determine a score for unaccounted damages. Instead, they reviewed the list of problem
      areas and assigned scores on a case-by-case basis.
   "While risk management considerations should be kept separate from risk assessment, it
is still important to anticipate and discuss future changes in environmental risk. For the
findings of a comparative risk project to remain relevant on a long-term basis, population
growth and the values of the community regarding development choices need to be con-
sidered. For example, land-development choices to build housing, roads, and factories of
to protect natural habitats and tourist attractions will be affected by demographic trends
and will influence the future risks posed by environmental problem's. Cleaner industrial
processes, substitute chemicals, efficient agricultural processes, and other technological
innovations may also affect the future risks associated with problem areas.
   Examples of how population and trend information can affect analysis of environmen-
tal problem areas include:
   •  Industrial viability. Trends in international prices,  taxes, incorporation laws, etc, will
      affect the ability of certain industries to produce goods competitively. The future of
      many environmental problems will be affected by the survival and level of activity of
      specific industries in an area. If, for example, a drop in the price of oil or in the pro-
      ductivity of wells were to stop production in a given locale, oil spills, coastal habitat
      destruction, and other, forms of air> water, and land pollution might be eliminated. It
      is important to know whether a given industry will survive economically when
      assessing ib long-term impacts on the quality of life.
September 1993                                           .                       2.4-33

  A Guidebook to Comparing Risks and Setting Environmentd ''Priorities
  Adams, R.M, J.D. Glyer, S.L Johnson, and B .AJMcCarl. "A Reassessment of the Econo-
  mic Effects of Ozone on U.S. Agriculture." Journal of Air Pollution Control, vol  39  '
  (1989):960-968.                             !

  Galloway, J.M., R.F.Darwin, and RJ. Nesse. Economic Effects of Hypothetical Reductions in           .     ,
  Tree Growth in the Northeastern and Southeastern United States, prepared for U.S. EPA
  under a Related Services Agreement with the U.S. Department of Energy (Contract No.
  DE-AC06-76RLO 1830) by Pacific Northwest Laboratories. August 1986.
                                             ]      .           • .                      - '
  Chestnut, Lauraine, et al. Santa Clara Criteria Air Pollutant Benefit Analysis.  Santa Clara,
  CA. May 1987.                       ..;!'.                       ":                 .

  Hall, Jane, et al.  Economic Assessment of the Health Benefits from Improveinent in Air
  Quality in the South Coast Air Basin. Final Report to South Coast Air Quality
  Management Board. June 1989.               |

  Hartun ian, N.S.  The Incidence and Economic Costs of Major Health Impairments.
  Lexington, MA; Lexington Books, D.C. Heath arid Co. 1981.          i
  Heck, Walter, et al. "A Reassessment of Crop Loss from Ozone." Environmental Science
 and Technology, vol. 17. no. 12 (1983): 573A-581A.

 Journal of Environmental Economics and Management QEEM), vol.  1.8, no. 2 (1990).
 Louisiana. Department of Natural Resources/US, Environmental Protection  Agency.''•
 LEAP to 2000: Louisiana Environmental Action Plan. June 199 la.

 Louisiana.  Department of Natural Resources, "Comparative Risk Project: Briefing                      .    .
 Memorandum on Quality of Life Analysis." Baton Rouge, LA. March 1991 b.
 Louisiana. Department of Natural Resources. Comparative Risk Project: Quality of Life
 Cost Estimates. Prepared by Stephen Farber,  Department of Economics, Louisiana State
 University. Baton Rouge, LA. December 1990.   ;
 McClelland, G., W Schultze, and B. Kurd. "The Effect of Risk Beliefs on Property
 Values: A Case Study of a Hazardous Waste Site." Unpublished. 1989.

 Michaels, G.,V.K. Smith, and D.Harrison. "Market Segmentation and Valuing               *
 Amenities With Hedonic Models: A Case. Study of Hazardous Waste Sites." Journal of
 Urban Economics, vol. 28 (1990): 223-242.       j

 Northeast Center for Comparative Risk (NCCR). j Personal communication with Richard
 Minard. July 1992.                            |

 Oge, Marge. "Conversation with Marge Oge." Mobility, vol. 11, no. 6 (June 1990): 43-46.                        •>
 Rice, D.P. "The Economic Costs of Illness: A Replication and Update." Health Care
 Financing Review, vol. 7, no. 1 (Nov. 1985): 61-80,                '

 Searde. Office of Long-Range Planning. Environmental Risks in Seattle: A Cp^nparative
ylif«swK»^ Seattle Environmental Priorities Project: A Report by the Technical Advisory                           \

2>4-36                                       j                     .September 1993

                                                            2.4 Quality-of-Life Assessments
END NOTES                                                              ,
1 The dollar figures given in the remainder of this chapter are from different years..
Analysts using the formulas presented should adjust values to a consistent dollar year. To
do so, a price-deflator index, such as the Consumer Price Index, or more specific price
indices for agricultural products, medical services, etc.', may be used. Two sources of price-
deflator tables are The [annual] Economic Report of the President, compiled by the Council
of Economic Advisors, and The Survey of Current Business (July issues).      ,
2 If there are large variations in pollutant concentrations across the region, it may be
preferable to estimate damages on a state-by-state basis and add the results.
3 Consumer surplus and willingness to pay are synonymous in those instances where the
"good" is free—e.g., the willingness to pay for a day of recreational fishing is the same as
the consumer surplus (assuming there is no charge for fishing).
4 EPA has estimated the background ozone level to be between 0.02 and 0.03 ppm.
5 Non-use value describes a willingness to pay to improve a resource that the individual
may not immediately plan to use. Several types of non-use value exist, including "option
value" (willingness to pay to preserve the option of using the resource), "existence value"
(willingness to pay to simply know that the*quality of a resource is being preserved),
"altruism" (knowing the resource is preserved for others' current use), and "bequest value"
(knowing the resource is preserved for future generations'use).
6 Other damages are possible (e.g., increased travel costs).
7 The model used in the document (RIA) from which this equation is drawn has been
reestimated  to correct for a minor calculation error. This was done by EPA Region IV in a
welfare effects study as a part of its comparative risk evaluation (EPA 1990e).
8 The above model is not appropriate for measuring damages in areas with high-baseline
visual ranges (i.e., greater than 90 km). The available models and contingent-valuation  ,
studies used to estimate this equation address visual ranges of up to only about 50 km. As
a result, if existing visibility figures of over, approximately 90 km are used in the equation,
the estimated willingness to pay will be negative—an illogical  result.   \
9 The one-mile radius is typically applied because two of the three studies cited above
frame the willingness-to-pay question in terms of miles from the site.
10 Frequently, data are available on the total number of contaminated wells in a state or
region. This figure must be divided by an estimate of the time frame over which the wells
were contaminated to arrive at an estimate of the number of wells contaminated per year.
 11 The estimates of treatment costs in the documents from which these figures are drawn
have been called into question and are under review.
 12 This is a very rough approximation of the potential change in UV-B radiation over time;
the analyst should attempt to locate more precise information as it becomes available.
 13 The option illustrated here is  based on the work done by Region I; a more detailed
description  can be found in Unfinished Business in New England; A Comparative Assessment
 of Environmental Problems—Societal Costs Work Group Kef on, April 1990.

 September  1993                                   '       ,                  2-4'35

 A Guidebook to Comparing Risks and Setting Environmental Priorities
                                     .- • -  •_  i- . ..,£ -      ,
 U.S. EPA. Office of Ground Water and Drinking Water. Regulatory Impact Analysis of
 Proposed National Primary Drinking Water Regulations for Synthetic Organic Chemicals.
 March 1989c. Addendum, October 1990.     ^
 U.S. EPA. Office of Air and Radiation. "Regulatory Impact Analysis (RIA) on the
 National Ambient Air Quality Standards for Sulfur Oxides." Appendix A, Draft.
 Washington, D.C. March 1988a.             j
 U.S. EPA. Office of Solid Waste. Subtitle D Risk Model Appendix E. Washington, D.C
 August 1988b.                             ;               .

 U.S. EPA, Region III. Cross-Media Project: Welfare Damages Work Group. Explanation
 of Ranking Process. Philadelphia, PA. 1988c    >
 U.S. EPA. Office of Research and Development. Radon Reduction Methods: A '-
 Homeowner's Guide. Washington, D.C. September 1987.
 U.S. EPA. Office of Air Quality Planning and Standards. Comparative Risks for Primary
 Air Pollutants.  Vols. I and II. Draft Final Report. Washington, D.C. 1986a,
   - "  .       -             "   .     -             '              ,'           f •    %_
 U.S. EPA. Office of Policy Analysis. A Damage Function Assessment of Building Materials:
 The Impact of Acid Deposition.  Prepared by Horn  et al. Washington, D.C. 1 986b.

 U.S. EPA. Office of Policy Analysis. Costs and Benefits of Reducing Lead in Gasoline: Final
 Regulatory Impact Analysis. Washington, D.C. 19;85a.  '"

 U.S. EPA. Office of Policy Analysis. A Methodological Approach to an Economic Analysis of
 the Beneficial Outcomes of Water Quality Improvements from Sewage Treatment Plant    \
 Upgrading and Combined Sewer Overflows. Washington, D.C. 1 98 5b.
 U.S. EPA, 'Damage Cost Models for Pollution Effects on Material. Prepared by E. McCarthy
 et al. Research  Triangle Park, NC. 1983.  '    }
                 '                          •
 U.S. EPA. Office of Research  and Development!  Air Quality Criteria for  Oxides of
        . Washington, D.C. 1982.          .  |
Vaughan, W.J., and C.S. Russell. "Valuing a Fishing Day: An Application of a Systematic
Varying Parameter Model." Land Economics, vol. 58, no. 4 (Nov. 1982): 450-463.
Vermont. Agency of Natural Resources. Environment 1991: Risks to Vermont and
Vermonters. Technical Appendix. Waterbury, VT. 1991.  '
Walsh, R,G., et al.  Review of Outdoor Recreation Economic Demand Studies With Non-
Market Benefit Estimates. Prepared for Colorado Water Resources Institute. Fort Collins,
CO, 1988.
September 1993

                                                           2.4 Quality-ef-Ltfi Assessments'
 Committee. Seattle, WA Oaober 1991.
 Smith, V.K., and W. H. Dcsvouges. "The Value of Avoiding a LULU: Hazardous Waste
 Disposal Sites." The Review of Economics and Statistics, vol. 63, no. 2 (May.1986): 293-299.
 Teramura, A.H. "Overview of Our Current State of Knowledge of UV Effects on Plants."
 In Effects of Changes in Stratospheric Ozone and Global Climate. U.S. EPA/United Nations.
 Washington, D.C. 1986.
 U.S. Environmental Protection Agency (U.S. EPA). Region IV. FY92-96 Strategic Plan.
 Atlanta, GA. 1992.
 U.S. EPA. Region II. Office of Policy and Management. Region II Risk Ranking Project,
 Economic/Welfare Damages from Pollution: Relative Ranking and Problem Analyses. New
 York, NY. 199 la.
 U.S. EPA. Drinking Water Research Division. Risk Reduction Engineering Laboratory.
 Personal communication. Cincinnati, OH. September 1991 b.
 U.S. EPA. Office of Policy, Planning and Evaluation. Valuation of Forest Ecosystem
 Services: Estimating the Benefits of Controlling Climate'Change.'Washingon, D.C.
 September 1991c.                       »
 U.S. EPA. Office of Solid Waste. Potential Benefits of Preventing Contamination of
 Wetlands Due to Releases from Hazardous Waste Facilities: Analysis of Selected Sites.
 Washington, D.C March 1991 d.
 U.S. EPA.  Science Advisory Board. Reducing Risks, Appendix A: pp. 23, 26, 36. Report
 of the Ecology and Welfare Subcommittee. Washington, D.C. September 1990a.
 U.S. EPA, Office of Air Quality Planning and Standards/U.S. National Park Service, Air
 Quality Management Division. 1990 Preservation Values for Visibility Protection at the
 National Parks. Draft Final Report prepared by LG. Chestnut and R.D. Rowe.
Washington, D.C. February 1990b.
 U.S. EPA.  Office of Policy Analysis. Ecosystem  Services and Their Valuation. Washington,
 D.C. February 1990c.
 U.S. EPA Region I. Unfinished Business in New England: A Comparative Assessment of
 Environmental Problems. A Report of the Societal Costs Work Group. Boston, MA. April
 1990d.                        .
 U.S. EPA. Region IV. Policy,  Planning, and Evaluation Branch. Comparative Risk
 Evaluation: We fare Effects Study. Atlanta, GA. 1990e.
 U.S. EPA.  Office of Air. Quality Planning and  Standards.  "Review of National Ambient
Air Quality Standard for Ozone: Assessment of Scientific and Technical Information."
Table XI-1. Staffpaper. Research Triangle Park, NC. June  1989a.
U.S. EPA.  Office of Ground Water and Drinking Water. Regulatory Impact Analysis:
 Benefits and Costs of Proposed National Primary Drinking Water Regulations for Inorganic
 Chemicals. Washington, D.C. March 1989b. Addendum, October 1990.
                            '•                       '                    *      • '

September 1993                              •'                    2.4-37



 A Guidebook to Comparing Risks aruL Setting Environmental Priorities  '
EXHIBITS                                                     ;
                       '                                         i
   3-1.1  Risk Management Steps			,	5
   3.1.2  Monitoring Progress Toward Goals....,,,	'.	6
   3.1.3  Examples of Criteria for Eval uating Risk Management Strategies	 6

REFERENCES	'C.	....	14
September 1993

                       3.1  RISK MANAGEMENT

Prerequisites to Risk Management.	%	,	,	 3

Risk Management Steps  	,	5
     Step 1: Set Environmental Goals  	: —	...5
     Step 2: Identify Criteria for Evaluating Risk Management Strategies		.'..,. 6 •
        Risk Reduction/Prevention Potential	,.6
        Statutory and Regulatory Authority	6
        Cost and Cost-Effectiveness	'.	\	7
        Technical Feasibility —..:	,	,	7'
     '   Speed/Ease of Implementation	7
        Environmental Equity	......7
     Step 3: Analyze Strategies to Achieve Environmental Goals  	8
        Pollution Prevention	 —	8
        Scientific and Technological Measures	 9
        Public Education/Outreach	9
        Market Incentives	9,
        Conventional "Command-and-Control" Regulations	 11
        Effective and Innovative Enforcement	,.	1:1 ,
        Interagcncy and International Cooperation	11
     Step 4: Select Implementation Strategies and Monitor Results   .........:	12
September 1993                                 '                           3-1-1

  A Guidebook to Comparing Risks and Setting Environmental Priorities
  certain exposures to lead in the environment. Therefore, in order to develop appropriate
  risk-reduction or -prevention strategies, it is important to understand which source seems
  to be contributing the most to the problem and what actions are currently being taken" to
  address it.         '                      .                     ,
    Evaluating the effectiveness of existing programs is important in order to get a sense of
  whether a new program is needed or if the current program can meet the environmental
  goal. When considering shifting resources among programs, the net risk reduction of any
  actions that might be taken should be considered. This entails selecting die risk manage-
  ment approach that most effectively reduces or prevents risk. It is important to remember
  that some problems may pose lowe.r risk because: (1) there is an effective control program
  in place that keeps the risks low, or (2) the problem area does riot pose  inherently high
  risks. To make this determination, it  is necessary to know how well die control program is
  currently addressing risks, at what cost, and what changes in risk reduction  and cost are
  likely to occur in the future. In the case of risks that are being effectively managed and
  would likely increase in the absence of such efforts;, disinvesting resources from that pro-
  gram might result in a net gain of risk. However, in the case of a problem area posing rela-
  tively lower risks, there could be a case for deferring further investments until more serious.
  risks are addressed.       .                   »  1            .,-•;.._
    In addition, if a comparative risk project is intended to identify emerging environmen-
  tal threats in addition to existing risks, then the analysis must encompass anticipated
  changes or trends in risk. Risks can increase or decrease because of changes in technology,
  economic conditions, and/or demographic factors. Some of these issues may^have been
, 'accounted for in the risk rankings. If they have noi: been accounted for, then a trend
' analysis can be accomplished in a relatively non-quantitative fashion using work group
  members' best professional judgment, or using a more  rigorous quantitative approach
  involving modeling and other forecasting techniques. For example, agricultural forecasts
  may shed light on the need for certain non-point source water pollution controls and how
  quickly they will be needed to meet certain environmental goals.            ,
    Uncertainty is often very prominent in comparative risk projects. In some cases, the
  uncertainty surrounding a specific problem area is relatively small. However, in other
 cases, uncertainty can be quite large and have a profound effect upon the riskrranking and
 priority-setting processes. When the uncertainty is large, it may be appropriate to focus on
 research strategies in order to better articulate and eventually better solve the problem. If
 significant risks are not likely to occur while research is being conducted on  the problem,
 and die cost of the research is affordable, then research  may be die most appropriate
 course of action to take. However, if die cost of die risk-reduction or -prevention strategies
 is low compared  to die costs of research and possible adverse effects which might occur
 during diis period, .dien it may be advantageous to take immediate action rather than
 spending the time and resources to gather better data. In many instances, it may be most
 appropriate to consider low-cost risk-reduction and -prevention strategies concurrently   :
 widi research efforts.
September 1993

                                                                  3.7 Risk Management
        Risk management is a decision-making process in which the ranking results from
        the risk assessment process are integrated with economic, technical, social, and
        political considerations to generate a prioritized set of risk-reduction or -preven-
tion strategies that will achieve environmental goals. Whereas risk assessment asks how
bad is the problem, risk  management asks what can and should be done about it. The
effectiveness of risk management strategies can be monitored and evaluated in terms of the
progress made toward goals using environmental indicators, such as a reduction in the  •
ambient concentration of a certain pollutant or an increase in the biological diversity of a
given ecosystem.
   Translating analysis into action  represents the culmination ,or "payoff" of the compara- '
tive risk process. Despite the brevity of this chapter, it is important to note that as much
thought and analysis should be given to selecting the most appropriate risk- reduction or -
prevention strategies during the risk management process as is  devoted to assessing and
ranking problem areas during the risk assessment process. Ideally, the end result of this
risk management process is a set of sound, long-term risk-reductioa-or -prevention strate-
gies that will achieve broadly supported environmental goals in a cost-effective manner.
   One of the most important aspects of risk management is the  integration of the con-
cerns and values of the public, other agencies, public interest groups, and the regulated
community to set clear goals for the environment, specific criteria for evaluating strategies,
and an open process for selecting risk management priorities to implement.

   Before launching the risk management phase of a comparative risk project, it is impor-
tant to have several things in  order. First, it is necessary to have a ranking of human
health, ecological, and quality-of-life risks. Second, it is important'to review the goals of
the comparative risk project to ensure that the risk management phase is structured to
meet the goals and to account for additional goals that may have developed since the pro-
ject was started. Third, the risk management process should include participants from the
risk analysis phase of the project and participants who can help to promote the implemen-
tation of selected risk management strategies.                        .
   The risk rankings are  an important component of the risk management process. While
the risk rankings do not  in themselves represent an organization's priorities, they are an
appropriate starting point for considering risk-reduction or -prevention strategies. To
determine which strategies may work best, members of the risk management work group
must understand the "anatomy of risk." That is, not  only identifying which problems pose
the highest risks, but understanding why they pose the highest risks and who is bearing
those risks. It is important to understand which stressors are creating the most significant
risks and which human populations and ecological receptors are at greatest risk, as well as
the effectiveness of existing programs designed to address these risks. For example, high
blood-lead levels in children can result from contaminated drinking water, lead paint, or
lead dust deposited in soils. However, there may be programs already in place to address
September 1993                                       •                      3.1-3

 A Guidebook so Comparing Risks dnd Setting Environmental Priorities
                                  Exhibit 3.1.2:
                       Monitoring Progress Toward Goals

^- — "*•' GOAL SETTING
2000 2000
 Step 2: Identify Criteria for Evaluating Risk Management Strategies
   Once a set of specific, measurable goals has been established, then it is necessary to
 establish risk reduction or prevention strategies to achieve these goals. Before selecting risk
 management strategies, it is necessary to first decide what criteria will be used to evaluate
 possible risk management strategies. Then, each proposed strategy can be evaluated
 against a common set of criteria to determine its  feasibility and relative advantage com-
 pared to other strategies that might be employed. For instance, almost any risk manage-
 ment strategy will need to be technologically and economically feasible. Several criteria
 that have been consistently selected in past projects; to evaluate these strategies are listed in
.Exhibit 3.1.3. The criteria presented here are merely guidelines; other criteria may be
 added  or substituted, depending oil the specific objectives of the project.  ]

                                  Exhibit 3.1.3:
       Examples of Criteria for Evaluating Risk Management Strategies
       Risk reduction/prevention potential  • Technical feasibility

       Statutory and regulatory authority   • Speed/ease of implementation
       Cost and cost-effectiveness         ,'• Environmental equity'
Risk Reduction/Prevention Potential      '
   Risk reduction refers to the amount of risk posed by an environmental problem that is
estimated will be reduced by implementing a proposed strategy. Risk reduction presumes
that an existing environmental problem poses risks,: However, for some environmental
strategies, it is the amount of risk prevented, as opposed to the amount or risk reduced,
that is important to estimate in evaluating a proposed strategy. In terms of evaluating pro-
posed strategies, risk reduction and risk prevention are equivalent.
Statutory and Regulatory Authority            ,
   There must be a legal basis for any risk management strategy that is implemented. This
requires determining if the authority exists to implement proposed strategies. If authority
exists, then it must be determined where it is located (e.g., with another agency or level of
government) and how it can be most appropriately exercised. When statutory authorities
impede risk reduction actions that an agency would like to take, project participants must
September 1993

                                                                 3.1 Risk Management
   Risk management can be done in a variety of ways, bur .there are a number of steps that
have been consistently used in past and current comparative risk projects. The four'steps
outlined in Exhibit 3.1.1 represent one way to approach this process. These steps are not
meant to be prescriptive, but they can be used as a general guide to the process. They are
described in more detail later on in this section..
                                 Exhibit 3.1.1:
                            Risk Management Steps
                     Step 1: Set Environmental Goals

                     Step 2: Identify Criteria for Evaluating
                             Risk Management Strategies
                     Step 3: Propose and Analyze Strategies
                             to Achieve Goals
                     Step 4: Select Strategies for Implement-
                             ation and Monitor Results
Step 1: Set Environmental Goals
   The development and use of measurable environmental goals can provide strategic
direction for the long-term efforts needed to address environmental problems. The goal-
development process—if it includes participation across a broad range of government
agencies with environmental responsibilities, private stakeholders in environmental policy,
and the public—is an opportunity to build consensus on environmental priorities. Once
goals are set, they can provide some perspective on the kinds of strategies that are needed
to address some of the high risks that have been articulated in the risk assessment phase of
the project. Additionally, goals are a good, starting point for thinking about ways that one
can measure progress after management strategies have been selected. For example, if
nutrient runoff from agricultural fertilizer use is a significant risk, then one possible goal
might be to reduce nutrient levels by 50 percent within 10 years.
   Exhibit 3.1.2 depicts  two different scenarios of how monitoring goals can help man-
agers determine whether they are successfully accomplishing their objectives. On the left-
hand side of Exhibit 3.1.2, it appears that current efforts to meet the hypothetical goal are
making satisfactory progress toward that goal. This goal might represent an increase in the
number of stream miles  which meet all federal and state standards/designated uses by the
year 2000. The graphic on the right-hand side depicts a situation where progress toward
the goal does not appear to be satisfactory. In fact, it appears that the trend is away from
the goal that has been set. This may alert managers to the need for a review and possible,
change in the current strategy. As a general rule, goals should be important, measurable,
understandable, and set  within a certain time horizon.
 September 1993

                    •  *        .   •  "    -       !  •
   A Cutback to Comparing Risks and. Setting Environmental .Priorities
   developed now to improve our understanding of the sources, routes of exposure, and
   health effects on specific populations at higher risk, such as ethnic minorities or'individu-
   als in high-risk occupations or neighborhoods,   i   .             '    ;

   Step 3: Analyze Strategies to Achieve Environmental Goals
     The purpose of this step, is to generate and analyze risk management strategies through
  an iterative process that gradually focuses on the most effective means of achieving envi-
  ronmental goals. To start the process, work group! members may propose risk reduction or
  prevention strategies from a "tool box" of risk management approaches. Proposed strate-
  gies can then be analyzed in terms of the criteria that have been selected by the work
  group to evaluate the merits of various strategies. The more promising strategies can then
  be subjected to more rigorous analysis until consensus is reached. By focusing the analysis
  of strategies on environmental goals,  it is more likely that common links between different
  problems will be identified and simultaneously addressed.
    It may be very helpful to begin this process by introducing work group members to a
  round-table discussion of various risk management approaches and how they work For
  instance, managers have increasingly recognized that preventing pollution from occurring
  in the first place is generally preferable to control and abatement activities after the fact.
  Thus, pollution prevention has become a powerful, risk management approach. Other
  examples of risk management approaches include:';
    • Scientific and technological measures
    •  Provision of information to the public        ,
          >                 .                    i'                 .'I'-'
    •  Market incentives and disincentives         I                     i
    •  Conventional regulations                  ;            '               •   ..
    •  Effective and innovative enforcement       ;
    0  Interagency and international cooperation
                                               i    ••''-''•• '!'-•    '    '  •
 Pollution Prevention   ...'..           :                    (
   One of the recommendations of the Science Advisory Board's (SAB's) Strategic Options
 Subcommittee was that pollution prevention "should consistently be the most important
 approach for reducing environmental risks  over the long term" (EPA 1990). The subcom-
 mittee defined, pollution prevention as:           i       .
          «             .                       !                        '
        changes in raw materials, products or technologies of production which reduce the use of
        hazardous materials, energy, water, or other resources and/or the creation! of pollutants or
        destructive results, without creating new risks of concern;
   Pollution prevention can be implemented in a number of ways, such as market incen-
tives,: expanded community right-to-know programs, conventional regulations, and gov-
ernment procurement policies that promote pollution prevention. Many of the most
promising pollution-prevention initiatives focus on strategies that address several problems
simultaneously, such as  toxics-use reduction, increased energy efficiency and conservation,
or a comprehensive agricultural policy.
3<1"8 '                                                           ,  September 1993

                                                                  3.1 Risk Management
assess the possibility of changing them. This may require working cooperatively with other
agencies, working with other levels of government, seeking new authorities or changes in
existing authority from a state legislature, or encouraging the private sector to take volun-
tary actions to reduce or prevent risks. The state of Washington passed several new pieces
of legislation as a result of conducting a comparative risk project.
Cost and Cost-Effectiveness
  In evaluating risk management strategies, it is important to consider both the cost and
cost-effectiveness of the option. The cost of an option can be analyzed in a number of
ways. It might include the cost of the strategy to the state government, the cost to the pri-
vate sector, and/or the cost to the general public either in terms of taxes or in substitution
costs associated with  behavioral changes.
  Cost-effectiveness  refers to the cost of implementing a risk reduction or prevention strat-
egy relative to the amount of expected environmental improvement or risk reduction. In
looking at both cost and cost-effectiveness, it is important to determine a time frame for
calculating cost-effectiveness that is consistent with the goals associated with the strategy.
Technical Feasibility
  The technical feasibility of risk management strategies must be considered and evaluat-
ed. Effective' "off-the-shelP technologies may.be readily available for some environmental
problems, but may hot exist'or may be prohibitively expensive for other environmental
problems. In some cases, technological "fixes" may hot be satisfactory or even possible. For
instance, it is far more effective technically and financially to prevent ground-water conta-
mination than to remediate contaminated ground-water supplies.
Speed/Ease of Implementation
   There may be some strategies that are cost-effective and technically feasible, but which
cannot be easily or quickly implemented. Some, may require a multiyear effort before
results can be seen. For example, an education program  targeted toward public schools
may take a long time to show results if the goal is to permanently change the public school
curriculum. This doesn't mean that the strategy should not be pursued; rather, it means
that expectations should be realistic when making public commitments of this nature. It
may also be advisable to combine some strategies offering short-term results with other
strategies \yith longer time frames before results can reasonably be expected. Enforceability
is another aspect of implementation that is very important, relating to the feasibility and
case of obtaining private firms'compliance with the strategy.
Environmental Equity
   Specific populations can be at higher risk because they are systematically exposed to
higher levels of harmful materials (e.g., migrant farm workers) or because they are more
susceptible to developing health effects (e.g., poor urban women who have limited, access
to health care services). Risk management strategies can be designed to explicitly address
environmental-equity concerns. The ability to select risk management strategies that
address equity concerns is greatly enhanced by analyzing the risk burden on specific popu-
lations during the risk analysis phase of a comparative risk project. Methods are, being.

September 1993                                               .   .           ,3-1-7

A Guidebook to Comparing Risks ami Setting Environmental Priorities
the most efficient means of reducing pollution in order to reduce their costs. It is increas-
ingly accepted that market-oriented risk management approaches are needed in the future
to achieve the socially optimal, level of environmental protection in a cost-effective way. _
   Economic incentives can be divided into five categories^ They are:
   • Creation of Markets—The creation of tradablc government-issued marketable per-
     mits to discharge or emit pollutants or use scarce environmental resources. 'An
     amount of pollution caused by an activity is established by legislation and then the
     right to conduct that activity is allotted among firms in the form of permits. A
     prominent example of this is the "bubble" policy for certain air pollutants (i.e., sul-
     furic and nitric precursors to acid  rain) in specific areas. Firms that can more easily
     reduce the amount of pollutants they emit below the allowable level have the right to
     sell or trade their surplus "shares" to other firms. They may also "bank" the extra
     "shares" for use in future years. On the other hand, firms with high pollution control
     costs will have an incentive to buy permits rather than invest in more expensive con-
     trol technologies. Over time, the level of pollution or "ceiling" is lowered to achieve
     healthier levels of environmental protection. Government policies can also be used
     to reduce barriers to market entry.          |            -
                                              !' *         :           ' -
   • Monetary Incentives—"Pollution charges'~deiigned to change market incentives, such
     as providing or eliminating environmentally damaging government subsidies. These
     can take the form of user fees that have the principal motivation of revenue genera-
     tion, or taxes that are viewed as transitional instruments and revenue-neutral. In the-
     ory, fees and taxes will reduce pollution up to the point where the marginal costs of
     control equals the amount of the fee or tax. They may also be used in conjunction
     with other regulatory controls.            |
   • Deposit-Refund Systems—Government policies to discourage the disposal of natural
     resources by encouraging central collection efforts for their reuse. A surcharge is
     levied on an item (e.g., a beverage container) at the time of purchase. The surcharge
     is refunded when the item is returned after use.                   I
   • Procurement Policies—Thei public sector uses its own buying power to stimulate the
    _ development of markets, such as policies designed to encourage recycling and dis-
     courage preferential  treatment of products made from virgin materials. Such policies
     can be applied to a broad range of products-i
   • Revision of 'Legal Standards—Prescribing liability for damages from polluting activi-
     ties can provide a very powerful incentive to change current practicis. Liability can
     be joint, strict, several, and retroactive. Numerous other attributes of liability can be
     adjusted in support of environmental goals, such ~as changing the burden of proof,
     limiting damage awards, standing to sue, and allocating responsibility among the
     responsible parties. However, this tool should be used cautiously as litigation carries
     very high> socially unproductive transaction costs.
 3.1.10                     :                  !                      September 1993

                                                                  3.1 Risk Management
Scientific and Technological Measures
   Scientific and technological measures can be divided into two categories: (1) research
and development "activities to improve the scientific understanding of problems, and (2)
innovations in pollution-prevention approaches and pollution-control technologies.
   Research and development (R&D) studies arc undertaken to increase our understand-
ing and knowledge of environmental problems and the effectiveness of remedial and pol-
lution-control techniques. The facts, insights, principles, and technological advances
gained from such activities are very useful to those considering ways to control, reduce, or
prevent risks. However, risk managers and decision makers must be informed of the latest
developments in a wide range of fields so that this information can be incorporated into
the decision-making process. One of the major findings of the Report of the Expert Panel
on the Role of Science at EPA, Safeguarding the future: Credible Science, Credible Decisions,
is that "appropriate science advice and information is not considered early or often enough
in the decision-making process"  (EPA 1992c). Thus, it is very-important that risk manage-
ment team members who are familiar with the latest scientific and technological advances
share this information with the other work group members.
Public Education/Outreach
   Information can be provided  to consumers and producers of products and services that
can affect personal choices and consumer preferences. "Green labeling" and consumer
guides can help consumers reduce their own risks (e.g., information about radon), reduce
damages to their community or  to society (e.g., community right-to-know and informa-
tion on toxic waste disposal). Technical training and technology transfer can be used to
inform people and firms of cost-effective means of preventing or controlling pollution.
Environrflental audits can be used to observe operations at plants and suggest ways of pre-
venting or controlling emissions. These means of providing information to the public can
and should be used in a coordinated fashion to achieve environmental goals.
Maxket Incentives
   The most direct way to convey information to consumers and producers about the
adverse impacts of certain activities or products is to include the externalized costs of those
impacts in the prices of their activities or products. Because effective markets do not exist
for many natural resources, such as breathable air or clean rivers, there exists no financial
incentive for firms or individuals who pollute the environment to change their behavior.
Society ends up paying for these "negative externalities" in terms of increased health care
costs or environmental cleanup programs. The SAB noted in its report, Reducing Risk, that
"government policies should be  designed to encourage the socially optimal amount of
environmental protection by ensuring that consumers and producers face the full costs of
their decisions - not just their private costs, but the full social costs and consequences of
their actions" (EPA 1990).
   Market mechanisms can alter the behavior of polluters by changing the costs they face of
continuing their present practices or behaviors. Unlike regulations, incentive-based policies
influence rather than dictate the actions of individuals  and firms, and allow them to find
 September 1993                                                              3.1-9

 A Guidebook to Comparing Risks and Setting Environmental Priorities
    • A public policy study sponsored by ex-senai:ofs Tim Wirth and John Heinz. Project
      88: Harnessing Market Forces to Protect Our Environment. Washington, D.C. October
      1988.    •

 Step 4: Select Implementation Strategies and Monitor Results
    In this step of the process, risk management strategies are evaluated using the criteria
 that have been developed. Implementation strategies are developed for selected strategies
 that include goals and ways to measure progress toward those goals. Following an initial
 analysis of proposed risk management strategies, die work group will probably have nar-
 rowed the field of strategies down to a manageable number of the most promising to con-
 sider for implementation.                      !  .
    More refined analytic approaches can be used as the evaluation process moves closer to
 the decision-making point, such as assigning numerical values (e.g., four- or five-point
 scales), semi-quantitative values (e.g., high, medium, or low scores), or non-quantitative -
 descriptions to proposed strategies. In addition, weights can be added to different criteria
 to account for their importance relative to one another. However, extremely detailed
 weighting schemes and mechanistic formulas are not recommended since: they are unlikely
 to prove satisfactory to work group members and may not be easily communicated to a
 broader audience. On the other hand, non-quantitative approaches tend to be less struc-
 tured and rigid, allowing participants to bring more of their values and judgments to bear
 on the selection decisions through a process of group debate and discussion.
    Structuring the decision-making process in a way that maximizes its integrity and rele-
 vance is crucial to the likelihood that the work group's decisions will actually be carried
 out. A vigorous and open discussion of the relative advantages and disadvantages of strate-
 gies among a diverse and knowledgeable work group will lend integrity to the process. The
 process will more likely be relevant and credible to those who have the ultimate authority
 to implement  the strategies if it has included the right people, used appropriate criteria,
 and been reported clearly and persuasively.
   Once risk management strategies are selected, then they must be implemented and
 monitored over time to ensure that environmental conditions are changing in the direc-
 tion of the environmental goals that have been established. The risk management work
 group should be prepared to present well-defined and credible strategies that will achieve
 broadly supported goals in a way that meets the public's interests and needs.
 Implementation is more likely to succeed if the strategies are part of an overall strategic-
 plan that firmly ties environmental policies to budgets and meaningful, measurable
 results. Monitoring the actual results of the strategies will help environmental managers
 and the public know if their efforts are working or if they need to be adjusted and revised.
   The risk management process can help environmental managers identify the most
promising risk-reduction or -prevention opportunities, develop clear environmental goals
and strategies to achieve them, build public and political support for their programs and
policies, and focus on those measures of environmental quality that are most relevant to
September 1993

                                                                 3.1 Risk Management
Conventional "Command-and-CpntroP Regulations
   Over the past two decades, substantial resources at all levels of government have been
spent developing, administering, and enforcing traditional "command-and-control" regu-
lations that typically require large pollution sources to install engineering systems to
reduce pollutant discharges or emissions to the environment. This approach has resulted
in significant environmental gains, such as improved water quality due to massive invest-
ments in waste-water treatment plants. In contrast, the nature of many of the most signifi-
cant remaining problems makes them less amenable to command-and-control manage-
ment approaches. However, that does not mean that these kinds of requirements are never
appropriate. For example, standards can be very effective in forcing technology develop-
ment for pollution-prevention processes in new or retrofitted facilities.
Effective and Innovative Enforcement
   If a firm or  an individual perceives that the expected value of criminal penalties is less
than the additional cost of installing pollution-control equipment or changing production
processes, then they may decide that it is in their best economic interests to violate their
permit. The disincentives to violating the permit are the amount of the penalty and the
likelihood of getting caught as well as possible negative public reaction. Innovative
enforcement strategies include citizen suits, multimedia approaches to site inspections,
and environmental audits. For instance, by cross-referencing poor corporate behavior
across media, state and federal environmental enforcement officers have been able to build
stronger cases against corporate "bad actors."
Interagency and International Cooperation    >
   The interdisciplinary nature of comparative risk projects makes them ideal forums for
developing and implementing risk management strategies beyond the scope of any single
agency or level of government. In many cases, the policies and activities of other govern-
mental and private organizations in the energy, transportation, housing, development, agri-
culture, and taxation fields have contributed significantly to many environmental problems.
Therefore, the cooperation and participation of agencies from a number of different sectors
is important in finding lasting and comprehensive solutions to these problems.
   In addition, many environmental threats are now on a global scale, such as climate
change, ozone depletion, habitat destruction and degradation, and loss of species and bio-
diversity. These lands of transbouhdary threats cannot be adequately addressed by any
nation's individual efforts; they must be addressed within a multinational context. A more
full treatment of all of these risk management approaches can be found in the following
   •  U.S. EPA. Office of Policy, Planning, and Evaluation. Economic Incentives: Options
     for Environmental Protection. (21P-2001) March 199i.
   •  U.S. EPA. Science Advisory Board. Relative Risk Reduction Project, Appendix G
      Report of the Strategic Options Subcommittee. (EPA SAB-EC-90-021Q September
      1990.              •
   • OECD. Economic Instruments for Environmental Protection. Paris, France. 1989.

 September 1993                                                            3.1-11

  A GuuUbook to Comparing Risks and Setting ErarinmmfntaJ Priori ties
 REFERENCES,  '          •       •   -;',    , !./r"1-     '-'.'•''
 National Commission on die Environment.  Choosing a Sustainable Future. Island Press,
 Washington, D.C. January 1993.

 U.S. Agency for International Development. Bureau for Latin America iind the
 Caribbean. Environment Strategyfor'LatinAmerica andthe Caribbean. Washington, D.C.
 January 1993.                                '.-

 U.S. Environmental Protection Agency (U.S. EPA).  Office of Policy, Planning and
 Evaluation. An Overview of Risk-Based Priority Setting at EPA. Washington, D.C.
 November 1992a.

 U.S. EPA. Office of Policy, Planning and Evaluation. Preserving Our Future Today:
 Strategies and Framework. Washington, D.C. September 1992b.
 U:S. EPA. Science Advisory Board. Safeguarding the Future: Credible Science, Credible
 Decisions. Report of the Expert Panel on the Role of Science at EPA Washington, D.C.
 March 1992c.
 U.S. EPA. Science Advisory Board. Reducing Risk
 Environmental Protection. Report of the Strategic
 Reduction Project. Washington, D.C. September
 : Setting Priorities and Strategies for
Options Subcommittee: Relative Risk
                     September 1993

                                                                3.1 Risk Management
monitoring the impact of those programs and policies on the environment. Due to the feet
that there are more environmental problems to be addressed than resources allow, the risk
management process can help environmental managers make choices and set priorities.
September 1993                                      .                     3.1-13




  mi «


 A Guidebook to Comparing Rislu and Setting Environmental Priorities
         Phase 2: Analysis.	jg
         Phase 3: Risk Characterization  	:. j.	,	.19
         Phase 4: Comparison and Ranking of Risks  	.....;....	,...19
      Analyzing Quality-of-Life Impacts 	...:..	„...;..	..19
         Step 1: Identify Impacts and Determine the Values of the Community  	20
         Step 2: Identify and Define Evaluative Criteria	20
         Step 3: Collect and Analyze Data on Impacts	'.	;	..20
         Step 4: Characterize Impacts for All Problem Areas	21
         Step 5: Present Findings and Rank Problem Areas for Quality-of-Life Impacts  21
         Step 6: Analyze Future Environmental Conditions and Risk Miinagement
                Considerations	,1		.21
      Assessing Other Damages  	;	;	,!....!,	.22

 Data Sources and Collection	:		;	22
      Minimum Data Requirements	:	..,:..	......23
      Data Sources  	<	1	...,:..........'	  .23
         Local and Regional Sources	;..	'..„.....,!	,.........24
         National Sources	...;..	v..:>.........;	25,
         International Sources	t.	,	':	25
      Data Collection Issues.,.	».i	26
         Availability and Accessibility	26
         Cost of Data Acquisition		...I...			27
         Time	,	!......		27
         Validity and Accuracy	.|	 .27
                         * ~    '               '           .           i    .  . " .
 Risk Management	;	i	'....;			 .27
     Setting Environmental Goals	....28
     Establishing Risk Management Criteria ................".	......28
     Seleaing Strategies to Achieve Environmental Goals.	29
     Implementing Strategies and Monitoring the Results	30
     Alternative Views of Strategy Development.		31
TABLES                                    !
   4.1.1  Project Participants and Responsibilities	8
   4.1.2  Spatial Scale of Urban Environmental Problems	.........32
   4.1.3  Examples of Problems and Appropriate Types of Solutions	...33

EXHIBITS                                  1
   4.1.1  Sections of International Chapter  	\	....5
   4.1.2  Key Environmental Participants: Katowice, Poland...	.9
 ,  4.1.3  Problem-Area Lists for Bankok and Silesia Projects	„	13
   4.1.4  Microbial,Diseases Addressed in Bangkok Study	,	17
   4.1.5  Potential Data Needs and Sources......,;....	;,	24
September 1993


Major Differences for International Comparative Risk Projects	4

Project Planning and Start-up	5
     Objectives and Resources	•	"•
     Process Design and Organization 	............:	.7.
     Participant Selection and Responsibilities	•	7
     MajorTasks	••••	10

General Analytical Issues  	'.	•••-:	•	......10
     Time Frame Used for the Analysis	...........;	--10
     Geographic Scope of the Analysis	'•	11
     Underlying Driving Forces	••••••	......11
     Developing a List of Problem Areas and Definitions	•	12
       Agricultural Impacts	•	•	*2
       Extraction of Natural Resources ..'	•	•	'--13
       Urbanization Issues	•'	v	'•"
       Industrial Pollution	••••	"

Risk Analysis Methods	•	•••••	•	'-^
     Analyzing Risks to Human Health	•	15
       Step 1: Hazard Identification	<•	!5
       Step 2: Dose-Response Assessment	""•1^
       Step 3: Exposure Assessment	•	.•*"
       Step 4: Risk Characterization	•	•	....17
     Analyzing Ecological Risks	•	•*'
       Phase 1: Problem Formulation	«.«...	18

September 1993                 ,                                        4'1"1

   A G^hooKto Cornering Risks W String Environmental PrwritUs
        In the risk analysis phase, risks to human health
        economic and social impacts are assessed
        In .the risk management phase, environmental
        and non-risk factors. Environmental
        to such non-risk factors as cost-effectiveness
        and available resources.
           damages to ecosystems, and adverse
        their relative risks are ranked.
         priorities are established based on risk
priorities can differ from the risk ranking due
      i, technical feasibility,  public perception,

    The general concepts presented in this document are appropriate to ail applications of
  comparative risk analysis. Some important differences may exist in studies conducted in
  other countries that could influence the design and implementation of the study, such as:
    •  Different problem areas—For example, desertification and microbial disease.
    •  Different criteria for problem areas—For example, impacts on traditional life styles
       and economies.                        •  \
'•   •  Varied range and type of data sources, with international sources perhaps playing a
       greater role. -                        ^  !

    •  Different analytical methods because of differences in problem areas, available data,
       and available technical expertise.
    •  Different audiences, such as international development agencies.   '< '
    •   Different participating organizations because of the institutional setting.
    Because of all these potential differences, this section addresses organizational, design,
 and methodological issues that are specific to comparative risk studies outside the United
 States;Countries similar to the United States in both function and type of environmental
 problems can follow'the main text of this guidebook; those nations that are different can
 use this section as arough guide (see Exhibit 4.1.1). Thesection is aimed at an audience
 of potential project coordinators in both industrialized and non-industrialized nations, as
 well as senior environmental policy makers with some interest in the details of compara-
 tive risk analysis. Given the focus on differences, this section should not substitute for a
 careful reading of other sections of the document.!
   Comparative risk  represents a set of tools that can be used to address different environ-
 mental problems, but not all the tools are needed for every application, and new tools may
needed for specific studies. Resolution of these issues is an iterative process, requiring
adjustment throughout the study. As discussed in Section 1.2, a successful comparative
risk project will coordinate the original project design and objectives with the resources
and time available to complete the effort. This requires  careful attention in the early stages
of a project to the consistency between objectives and resources, process and structure, and
responsibilities and tasks. During the risk analysis phase of a project, the focus is on the
systematic analysis and  ranking of a number of environmental problem anas.
Subsequently, the risk management phase of a comparative risk project is the process by
                                                                   .September 1993

                                  4.1 International Application of the Comparative Risk Methodology
    In many countries, poor environmental conditions pose human health risks, damage
    ecological systems, and have adverse economic and social impacts. These countries
    often have limited resources to address these problems. In such situations, it is essen-
tial that governments establish environmental priorities and wisely invest available
resources by seeking the greatest risk reduction or prevention opportunities possible. To
make such decisions, information on the relative human health, ecological, and quality-of-
life impacts posed by various environmental problems is necessary.
   Comparative risk helps organizations evaluate environmental problems for a given geo-
graphic area and determine their relative risks. Subsequently, environmental priorities can  .
be set and  integrated with social arid economic policies. This process may be of particular
interest to  countries undergoing substantial economic development or change.
   Comparative risk may enhance environmental decisions that many countries are fac-
ing by:
   •  Building technical capabilities to collect and analyze environmental data and apply
      analytical results'to addressing environmental concerns.
   •  Building managerial capabilities, within and among environmental organizations, to  "
      better address environmental problems.
   •  Educating the public about environmental issues.
   •  Building capacity for public participation in the environmental decision-making  .
      process.          •   .
   •  Identifying environmental  research and data-collection priorities.
   •  Justifying requests for international environmental assistance.
   •  Determining risk management priorities for individual pollutant sources.
.   •  Allocating human and financial resources to effectively manage environmental
   •  Building institutional capabilities for environmental protection.
   •  Designing legislative and regulatory frameworks for controlling environmental
   •  Serving as the critical component of a Country Environmental Study linking the
      profiling function of environmental problems to an Environmental Action Plan.
   For example,, industrialized nations in Central Europe may derive significant insights
 into the merits of investing in environmental improvements during industrial restruaur-  '
 ing and the shift to a market economy. On the other hand, many non-industrial nations
 are facing the question of how environmental protection fits into economic-development
 initiatives. Comparative risk studies can help nations integrate economic-development and
 environmental-protection considerations.
   In a broad sense, the comparative risk process is composed of two steps:
 September 1993

                                   4.1 International Application, of the Comparative Risk Methodology
 which the risk rankings are considered along with other non-risk critei ia, such as cost-
 effectiveness, technical feasibility, and statutory authority, to develop risk reduction or pre-
 vention strategies to achieve environmental goals and set priorities for action.

                                  Exhibit 4.1.1:
   ~   .                  Sections of International Chapter
   The remainder of this section includes five subsections that parallel, the other
   sections of this document:
   Section 4
   Project Planning & Start-up
   General Analytical Issues
   Risk Analyses Methods
   Data Sources & Collection
   Risk Management
Section in Document
1.2:  Creating a Strong Foundation
2.1:  General Analytical Issues
2.2:  Human Health
2.3:  Ecological
2.4:  Quality of Life
3.1:  Risk Management
   Once die objectives for a project are identified, then a work plan oudining roles,
responsibilities, activities, and milestones should be developed to describe die project to
potential clients or stakeholders. Suggested steps in the project planning and start-up
phase include:                               I
   • Selecting a project director and support staff
   • Assembling a project public advisory and steering committee
   • Securing die support of key stakeholders  ;
,   • Defining project goals and objectives
   • Determining the role of public participation
   • Determining the project's organizational structure
   • Selecting technical work group members  !      .
   • Identifying the list of problem areas to analyzed
   • Setting time frame, milestones, and key technical work group taslcs
   Four major areas where studies in other countries differ from U.S. studies during die
project planning and start-up phase are: (1) objectives and resources, (2;) process design
and organization, (3) participant selection and responsibilities, and (4) major tasks.
September 1993

  A GriUcok to Cornering Risks 'nJ S
                                   4.1 International Application of the Comparative Risk Methodology
   •  Linkages to Other Social and Economic Issues. Environmental problems cannot be suc-
      cessfully managed if their solutions are sought in a vacuum from the other social and
      economic conditions and policies which affect how people live and use the environ-
      ment. Are these links addressed and are the right people participating in the project
      who can affect or influence those other policy areas?        "        -
      ,,  .                        ..-';.    '         .       |,

Process Design and Organization          ,
   Once the objectives are defined, project organizers must structure the comparative risk
process and the responsibilities and functions of participants. This involves a variety of
different considerations. The actual organization of functions should be linked closely
with the project's overall objectives, and organizational structures should not be adopted
without careful consideration of their usefulness for achieving specific: project goals. The
projects design and institutional structure should reflect generally accepted practices with-
in the nation or the region. The lead agency coordinating the project must have the
bureaucratic skill, technical expertise, and prestige to manage the project and act as an
advocate for implementation.               i
   In some cases, project organizers should add other functions to the project's structure.
For example, a key objective of a comparative risk study currently, being conducted in the
northern Silesia region of Czechoslovakia and Poland is to identify not only the opportu-
nities for greatest risk reduction, but also methods to pay for these reductions. As a result,
along with the ecological, human health, and quality-of-life work groups, a financing
work group has been established to identify and evaluate various revenue-raising mecha-
nisms for funding environmental improvements. Another objective in, the Silesia project is
to institutionalize environmental discussions between Czechs and Poles. To accomplish
this, a transboundary council was established to coordinate the activities of the steering
committees  and work groups in both countries.
   In other cases, functions considered necessary in U.S. projects may not be as important
in other countries.  For example, if the major project objective is to foiward requests to
international organizations for loans or grants to pay for environmental improvements or
to build the institutional strength of local environmental organizations, then it may not  be
as important to analyze the financial costs of the project and the avaihibility of public
funds to pay for it.                         |       •   •-

Participant Selection and Responsibilities
   As depicted in Table 4.1.1, the project can be organized around four functional groups:
the project manager, the'steering committee, Ac public advisory committee, and the tech-
nical work groups. Their responsibilities can include some of the following areas:
September 1993

A Guidebook to Comparing RisJes and Setting Environmental Priorities
                                   Table 4.1.1:
                     Project Participants and Responsibilities
Organizational Units
Project Manager
Steering Committee
Public Advisoiy
Technical Work Groups
Supervises all aspects of the project
Provides overall direction of the project
Ensures public participation in the process, and
ensures the project's work remains understandable,
relevant, and credible to the public
Perform data collection, data analysis, and prelim-
inary rankings
   The project manager and support staff are charged with rhe day-to-day management of
the effort. They are typically responsible for maintaining the overall intellectual consisten-
cy and quality of the technical analysis, motivating committees and clarifying their choices
and responsibilities, and selecting and directingvconsultants. They are also responsible for
ensuring that any necessary training is provided for project participants, including risk
assessment, risk communication, and introduction to comparative risk training. They are
heavily involved in "spreading the word" about the project.  This may involve talking to
the press and local civic and community groups, giving speeches, and writing articles. The
project manager typically needs a variety of skills, such as good written and oral communi-
cation skills, a thorough understanding of the political environment, and a high level of
enthusiasm and energy for the project.
   The steering committee provides guidance on major project policies and ground rules,
and represents the interests  of die broader public It may also be involved in setting the •
goals and objectives for the project, and approving the final rankings ,and priority actions.
The public advisory committee is the key liaison between the government participants and
the general public and major interest groups. It provides a forum for the essential two-way
communication about risk and public values between these groups. In some projects, these
two committees and their responsibilities are merged into one committee.
   During die risk analysis phase of comparative risk, the technical work groups collect
data; analyze the risks to heahh, ecology, and quality of life; and typically perform a pre-
liminary risk ranking. In die risk management phase of the process, the work groups may
work with members from other committees to develop and analyze a broad variety of
strategies to prevent or reduce risks from these environmental problems.
   Participants  involved in international comparative risk projects are likely to be different
from those described for U.S. projects in Section 1.2, especially if different objectives or
functions have  been defined. A recent study in  Poland identified a wide spectrum of
national and local agencies that had an integral role in the region's environmental protec-
tion, as depicted in Exhibit 4.1.2 (UNDP 1991).                                    .
September 1993

                                    4.1 International Application of the Comparative Risk Methodology
                                    Exhibit 4.1.2:
                 Key Environmental Participants: Katowice, Poland
   (Central Government

   Ministry of Environmental Protection,
     Natural Resources and Forestry
   Ministry of Health and Social Welfare
   Ministry of Land Economy and Building
   Ministry of Industry
   Ministry of Agriculture and Food Economy
   Ministry of Transportation and Marine Economy
   Ministry of Ownership Transformations
   Ministry of Labor and Social Policy
   Central Planning Office
   State Agency for Coal
   Agency for Agricultural Marketing
   Agency for Foreign Investments
   Nearly 2,000 registered organizations
   mat deal with the environment
. Regional Authorities

 Department of Ecology
 Department of Regional Policy
 Department of Public Ventures
 Department of Health
 Department of Architecture
  and Scenic Views
 Department of Geodesy

 Local Government           ,

 Health and Environment
 Local Ventures
 Municipal and Housing Economy
 Architecture, City Planning and
  Building Supervision
 Geodesy and Land Management
 Economic Activity
 Communications and Transportation
   Source: Boikiewicz, Jerzy et aL Environmental Profile of Katowice; Draft.
   UNDP/UNCHS/BRD Urban Management Program. Aiigun 1991.
   Project organizers should identify and recruit representatives from public interest and
policy advisory groups. If achieving a national consensus on the need for environmental
improvements is one objective of the study, then the steering committee should include key
opinion leaders from the community, non-governmental organizations, universities, politi-
cal figures, and the business community. Local or regional studies should rely heavily on
people from the affected municipality, as they sire likely to have the data, understanding,
and ability to address the problems. If mobilizing international assistance is the goal, then
including representatives of international organizations would be helpful to obtain dieir
support of the study results. Furthermore, it is particularly important to have consistent and
committed political and public support for the effort and to involve all potential stakehold-
ers in the process. In the past, some environmental plans have failed because they neglected
to consider the broader scope of stakeholders affected by environmentiil policy decisions.
   From a technical perspective, the project almost certainly will require support from
organizations and agencies that have not participated in environmental studies before.
Selection of technical staff should be driven by the set of environmental problems under
consideration and knowledge of the institutions and experts familiar with these problems.
Such experts may be affiliated with government institutes or agencies,, university research
programs, non-governmental organizations, or industry. For example^ if basic sanitation is
defined as an environmental problem, a health effects work group might include experts
on communicable diseases. Similarly, experts on the economics of rain forest harvesting
September 1993

A Guidebook to Comparing Risks and. Setting Environmental Priorities
mighc participate in asocial and economic damages work group if rain forest damage is an
important environmental problem.

Major Tasks
   Project planning and start-up also requires defining the major tasks to be accomplished.
Such tasks might include defining the risk analyses for human health, ecological, and
quality-of-life impacts; the risk management process; and the risk communication strategy.
A procedural task that project organizers might designate in the project start-up phase is
the establishment of an institutional mechanism for coordinating data-collection efforts.
For example, other agencies inside the government, non-governmental  organizations, and
foreign or international organizations, such as the U.S. EPA or the World Bank, collect
information that can be of use to a project. Early identification and coordination of'data
collection can save a great deal of time and effort.
   An example of the type of legitimate technical task that has not been particularly'rele-
vant in the risk management phase of U.S. studies is found in Central Europe. A key issue
is whether enterprises that are large polluters will survive privatization and restructuring of
the economy. To avoid recommending environmental investments in firms that may close
as a result of economic changes, a key task of risk management might be an economic-via-
bility analysis of financially troubled enterprises.

   This section highlights important differences between the analytical  methods used in
comparative risk studies in the United States and those used in other countries. The ana-
lytical methods used in projects in the United States are discussed in Sections 2.2 through
2.4 of this document. Other overarching analytical issues, such as the time frame and geo-
graphic scope of comparative risk projects, are addressed below. Further information on
these analytical issues can be found in Section 2.1.
'                                                         '                 /
Time Frame  Used for the Analysis
  As discussed in Section 2.1  (General Analytical Issues), the time frame for the analysis
should depend on the study's objectives. In certain applications, project organizers should
place increased emphasis on future risks. Trends in rates of population,  land use, and nat-
ural-resource depiction may be so severe that the scale and impact of a given environmen-
tal problem will  be vastly different from the current risk it poses. This may be particularly
important in countries where problems are rapidly getting worse. An analysis of future
conditions may be necessary because the lack of environmental controls and resources lim-
its current actions that might be taken to remedy the problem.
  Projects that employ pollution-prevention techniques may wish to estimate future risks
so that strategies can be developed to offset them.  For example, land-use trends that .
destroy valuable  habitats, such as rain forests or agricultural land, may have increasingly
serious and irreversible future impacts on ecosystems and the global environment. Such
4.1-10                                                             September 1993

                                  4.1 International Application of the Comparative Risk Mcthodologf
impacts will have subsequent human health, economic, and social ramifications that can
be factored into the analysis by projecting future effects.
                                      ".    i        .             I'-'-''
Geographic Scope of the Analysis
   One of the first issues to address in a comparative risk project is to define the geograph-
ic scope of the study. While most studies are national, regional, or local in scope, the pro-
ject area can focus on coastal zones, watersheds and airsheds, national parks, or even spe-
cific population groups.                     ;
   Defining the geographic boundaries of the study, area also includes determining how to
account for pollution entering the project area's boundaries from external sources as well as
pollution generated within the project area thai: causes risk to other people and ecosystems
outside the project area. It is useful to analyze and document these.types of transboundary
effects because this information can assist in selecting the most effective and equitable risk
management strategies. If such  issues are anticipated by project organisers, they can design
the comparative risk process to  include a transboundary analysis with representation from
all affected countries or regions within a single country.
   It may be worthwhile to consider global environmental issues, such as acid precipita-
tion, global warming, and stratospheric ozone depletion. Spatially, such problems are
global in terms of their sources  and impacts. Some regions may be only minor contribu-
tors to these problems and may not wish to spend their resources on analyzing the prob-
lem. Others may face severe impacts from these problems, but may be unable to address
them because the sources are not within their sphere of influence. However; it may be
worthwhile to consider these issues because of the reality of global interdependence, and
the need to highlight the magnitude of the threat.

Underlying Driving Forces
   In many undeveloped  and developing countries, critical environmental problems can-
not be solved without also addressing other economic and social issues, such as  rapid pop-
ulation growth, unsustainable patterns of natural-resource consumption, and inequitable
social and economic conditions. Environmental degradation is a significant arid growing
threat to development throughout the world, and the nexus between deteriorating eco- -
nomic and environmental conditions is experienced most acutely by poor families  in
developing countries. Underlying many environmental problems are human activities that
are the ultimate source of pollution and natural-resource degradation.
   Because of its broad underlying scope, die impact of population growth should  be con-
sidered in the analysis in a general fashion and not as a specific problem area. Rapid popu-
lation growth creates ever-increasing demands on the environment in terms of the need
for food, shelter, warmth, and medical, educational, and waste treatment services. For
example, the linkage between projected economic and population growth and the already
limited supply of energy produces a complex matrix of dependency, use, and impact.
Project participants are likely to realize, if they do not already, that all their efforts to
September 1993                            :                                 4.1-11

 A Guidebook to Comparing Risla and Setting Environmental Priorities
 address specific environmental problems will be overwhelmed by these underlying driving
 forces unless actions are taken to address them simultaneously.

 Developing a List of 'Problem Areas and Definitions
   An important substantive difference among comparative risk studies in different coun-
 tries is likely to be the need to emphasize different problem areas and use different criteria
 from U.S. projects to evaluate the impacts of these problems.
   Section 2.1 (General Analytical Issues) provides information on alternative approaches
 for defining problem areas, including by source type, media, pollutant,- and the organiza-
 tional structure of existing environmental programs, among others. Section 2.1 also speci-
 fies general criteria to apply in developing a problem area list. However, this problem list
 was developed to reflect environmental concerns in the United States and should be care-
 fully considered for its relevance to international studies.              .    -
   The various approaches to defining problem areas are not mutually exclusive. To highlight
 particularly important issues, it may be appropriate to define some problem areas according
 to media and control programs and others according to specific pollutants or health effects.
 For example, a study conducted in Bangkok, Thailand, generally preferred defining problem
 areas in ways related to existing environmental control programs, but found that a few pollu-
 tants (e.g., lead) involved sufficient health risks to warrant separate consideration (AID
 1990). The Silesia project's list is reflective of the environmental problems that have devel-
 oped in that region as an outgrowth of expansive industrial economic policies (EPA 1992),
 Both the Bangkok and Silesia projects' lists are included  in Exhibit 4.1.3.
   In defining problem areas, the range of effects (i.e., risks to human health, the  environ-
 ment,  and society's quality of life) posed by different problem areas should be carefully
 reviewed. Along with the typical effects analyzed, project organizers may wish to consider a
 broader range of social and cultural effects not commonly considered in U.S. studies. For
 example, developing nations face a broad range of public health problems directly linked to
 inadequate sanitary conditions. As a result, traditional environmental problems may need
 to be included in the analysis. It is also important to consider impacts caused by the under-
 ground economy. Illegal mining, poaching, and squatters, for example, have been shown to
 pose great risks to ecosystems. If these activities are linked to a specific problem area, then
 they should be included in the problem area definition and risk estimates.
   The remainder of this section highlights four broad categories of problem areas and
 effects that have not received much attention in U.S. studies, but which may be very
 important in other countries. These categories should not be considered exhaustive, as
some important problems are excluded. They are simply used as an organizational aid.
Agricultural Impacts
   The environmental impacts of agriculture may be very important in countries that are
highly dependent on this sector of the economy. In these countries, the consequences of
environmental degradation may be extreme, and specific agricultural problems may merit
special consideration. These problems include monoculture, desertification, salinization,

4.1-12                                                              September 1993

                                   4.1 International Application of the Comparative Risk Methodology
 depletion of soil resources or nutrients, overapplication of pesticides, or loss of arable land
 to urbanization.                  -•   ..   ";

                                  Exhibit 4.1.3:
             Problem-Area Lists for Bangkok and Silesia  Projects
               Bangkok Study
          Silesia Study
  •  Air pollution
     - Criteria air pollutants: paniculate      |
      matter, carbon monoxide, sulfur       j
      dioxide, ozone, nitrogen oxides
     (lead covered separately, in all media)    j
     - Toxic chemicals,

  • Water pollution     •      ".
      - Contamination of surface water       j
         - Effects on drinking water         i
         — Effects via direct contact, fish
           consumption, irrigation   .        ;
      - Contamination of ground water
      - Drinking-water treatment
       '                                 *•  '
  • Food contamination (pesticides and metals)

  • Solid and hazardous waste disposal

  • Lead and other metals

  • Microbial disease (can relate to water
   supply, human and solid waste disposal, etc.)
     1                                      r
  Source: U.S. Agency of International  Development. Office of
  Housing and Urban Prognnu. Ranking Environmental Risks
  in Bangkok, Thailand. December 1990.       •
• Drinking-water contamination

• Food contamination

• Communal and hazardous waste

• Surface water pollution

• Airpollution

• Occupational exposure
   Addressing these problems may require using a variety of additional direct measures of
effects, such as measuring species lost due to monoculture, area desertified, hectares lost to
salinization, or sou/nutrient depletion. These measures, in turn, may need to be translated
into estimates of health, ecological, economic, and social impacts. An example of this is
the effect of urban migration on traditional cultures due to unsustainalDle agricultural

Extraction of Natural Resources
   Similar to agriculture, countries that are highly dependent on natural resources might
develop a problem area list emphasizing the impacts of extracting specific natural
resources. Issues that might merit consideration, include the overharvesting of fuel wood,
depletion of fisheries, destruction of rain forests, mining effects such as subsidence, and
poaching of rare or threatened animals or plants.
September 1993

   A GmAbook to Comparing Risks W.Setting'ErwiranTntntal Priorities
     Direct measures of these, problems would need to be established, as well as an approach
   for determining their effects on human health, the environment, and society's quality of
   life. For example, overharvcsring of fuel wood might be described in terms of hectares
   damaged per year. This damage estimate could then be translated into economic losses by
   determining the incremental cost of replacement fuel, loss of sustainable harvestable crops,
   and lost recreational opportunities. The social impacts could be estimated by determining
   the resulting increase in urban migration and the loss of sacred lands and traditional prac-
   tices. The ecological effects from the overharvesting of fuel wood might include increased
  soil erosion, sedimentation of streams, decreased biodiversity, and the loss of aquatic and .
  terrestrial habitats.
  Urbanization Issues
     Environmental problems associated with stresses from urbanization on both urban and
  rural settlements vary greatly, depending on geographic and economic conditions.
  Pressures imposed on the environment by population growth in urban or rural areas
  include the impacts of human waste disposal, as well as the degradation of ecosystems or
  loss of natural habitats from outward sprawl of population centers. Urban areas are of
  great concern because of the coexistence and scale of impact of both traditional and mod-
  ern environmental problems. Urban migration places stress on infrastructure, depletes the
  natural resource base, and increases social stress.
    In U.S. studies, problem areas associated with waste disposal are typically well defined,
  such as municipal landfills and sewage treatment plants. However, this approach may not
  be appropriate in some countries, and it may be necessary to consider alternative problem
  definitions, such as human  waste, food wastes, or pollution of drinking water supplies.
  Direct measures for assessing the impacts of such problem areas would also be needed. For
 example, if inadequate human waste disposal is a major cause of microbial diseases, then
 the incidence of related diseases should be estimated. Similarly, infant mortality from
 waterborne disease (e.g., diarrhea and subsequent dehydration) might be a major consider-
 ation, if human waste disposal directly affects water supplies. In some cases, it may be nec-
 essary to start with incidence data and work backwards toward the sources.
 Industrial Pollution
   The degree and types of industrialization in a study area will, be an important consider-
 ation in determining how industrial problems. will be included in the problem area list.
 Industrial activity consists of the practices and processes used for manufacturing goods
 and services, including energy use. In some instances, project organizers may define specif-
 ic industrial sectors as separate problem areas, particularly if only a few significant indus-
 tries exist. For example,  if production of coke from coal is a major polluting industry, a
 problem area defined as "air  toxics from coke ovens" might be considered. In  nations
 where cottage industries are a significant part of the industrial base, they might be assessed
 as small sources of pollution.
   Project organizers might also focus on particular industrial pollutants of concern, such
as contributions of atmospheric sulfates from neighboring countries. In addition, a lack of
                                                                   September 1993

                                   4.1 International Afplication 'of the Gompomtivt Risk Methottology
 environmental standards in the work place might require detailed definitions of occupa-
 tional exposures and risks associated with specific occupations. Development of problem
 area lists for industrial pollution may also require alternative approaches to measuring
 effects. For example, high levels of occupational disease might call for greater emphasis on
 the costs of absenteeism caused by environmental illness and lost productivity,

   This section describes the analytical methods that are used to compare and rank differ-
 ent environmental problems within a common framework. Similar, but slightly different,
 methods are used to analyze human health, ecological, and quality-of-life risks. The crite-
 ria used to evaluate information and translate it into a common language for different
, environmental problems are also similar, with some important differences. And the data
 sources used for each varies as well. The three different analyses are discussed separately,
 but the discussion is based on the special aspects of international projects that distinguish
 them from U.S. studies. Therefore, the following discussion does not substitute for a care-
 ful reading of that subject in the relevant section in this document for ithose who will be
 conducting the analysis.
 -        --       '                       V  ' '  '          ~                   '
Analyzing Risks to Human Health     j
   The human health methodology for comparative risk projects uses the standard risk
 assessment methods to estimate the magnitude of the health impacts that may occur as a
 result  of exposure to pollutants. Section 2.2 (Assessing Environmental Risks to  Human
 Health) focuses on chemical contamination in industrialized settings. In non-industrial-
 ized countries where other environmental health problems are of great concern, other
 approaches may need to be developed to assess environmental health risks, such as those
 involving microbial disease and malnutrition.  \
                                            |      ,        '•'.',
   In general, the methods presented in Section 2.2 are directly applicable to any country.
The basic steps of assessing risks to human health are presented below. The first three
steps require some adjustments in their application if life styles and environmental prob-
 lems are markedly different from the domestic context presented in Section 2.2.
Step 1: Hazard Identification
   This step involves evaluating available data on the presence of, and hazard posed by, sub-
stances likely to cause adverse effects. Typically, in comparative risk projects, the most impor-
 tant and representative "stressor" or stressors for each problem area are selected for analysis.
Step 2: Dose-Response Assessment          j
   This step helps determine the degree of the effect or effects at different doses or levels
 of exposure to the substance. This relationship between the dose and response is often
 referred to as the potency or toxicity of the substance. EPA typically makes an important
distinction in the "threshold" of different harmful substances. It is assumed that there is no
 threshold or safe  level of exposure for carcinogenic substances, while there is assumed to
 September 1993                            j                  /              4.1-15

  Guidebook !O Comparing Risks and Semng Environmental Priorities
 be a level at which exposure to a substance with the potential to cause non-carcinogenic
 effects is considered to be below threshold or "safe."
   These first two steps can be bypassed if incidence data are available. As advocated in
 Section 2.2, incidence data are preferable because they simplify the process, as long as the
 causes of disease can be identified with enough certainty. Additionally, they give a more
 realistic estimate of actual effects than risk estimation. Underreporting, however, is z
 major concern, especially with non-terminal illnesses.
 Step 3: Exposure Assessment                                 .
   This step in the process traces the most important pathways by which human beings
 come into contact with or are exposed to a given substance. Having knowledge of the life
 styles and occupational patterns of people is necessary in order to effectively identify and
 estimate the magnitude, duration, and frequency of their exposure to harmful substances.
 Life styles and occupational patterns can be markedly different from country to country.
 For example, indoor air pollution may require not only a knowledge of the types of fuels
 used in the home, but also of cooking and heating practices, building materials and struc-
 tures, and ventilation  techniques. Where possible, the exposures of different spcioeconom-
 ic groups should be taken into account.              ,                               ,
                                           *                 i
   The values used for dose-response and exposure parameters should be carefully consid-
 ered in each instance,  since assumptions made for application to U.S. populations may
 not be appropriate for other countries. Cultural and physiological differences should be
 considered in determining consumption and exposure patterns. For example, in the
 United States, the average adult consumes approximately two liters of water per day and
weighs 70 kilograms; it would not be appropriate to apply these values to other countries
without justification. In some places, people may use bottled water for drinking purposes.
Genetic differences have also been known to alter dose-response relationships. Such differ-
ences, in general,  are minor compared to the magnitude and type of exposure. Therefore,
it is recommended that efforts be centered on identifying the magnitude and type of expo-
sure more than possible genetic dose-response differences.
   In the Bangkok study, microbiological diseases were a major human health threat.
Therefore, they were analyzed as a separate problem (see Exhibit 4.1.4).  In analyzing data
on the incidence of such disease, analysts may also encounter several  problems that were of
concern in the Bangkok study. One problem is that many of these diseases are not treated
and are not reported. As a result, analysts may need to indicate to decision makers that
their risk estimates (based on incidence data) probably represent underestimates of the
actual magnitude of the risk, although there is no way for them to know how much they
are underestimating the actual risks. Other adjustments may be necessary if microbid dis-
eases cannot be attributed solely to environmental causes. For example, poor personal
hygiene and food preparation or inadequate medical care may be of equal or greater
importance than environmental factors. Thus, in comparing the health risks from differ-
ent environmental problems, not ail the estimated cases of microbial disease should be
attributed to  environmental causes.                   .
4.1-16                                                             September 1993

                                    4.1 In£rrna.tional Application of'tbt Com-paraovt Risk
                                    Exhibh 4.1.4:
                    Microbial Diseases Addressed in Bangkok Stud;
      Key microbiological diseases
      that are environmentally related
      (partial list):
      These diseases are
      responsible for

      Primary routes of

      Environmental factors
      in disease
      factors in disease
 Acute diarrhea
'• Dysentery           .
 Enteric fever (typhoid, paratyphoid)
 Acute poliomyelitis
 Typhus and other rickettsioses

 6% of deaths in Bangkok
 850,000-1,700,000 estimated cases/year

 Human fecal to oral
 Vectors (mosquitos, rats, flies)

 Lack of water
 Lack of sewage conveyance
 Contaminated water
 Lack of sewage treatment
 Uincollected solid waste

' Poor personal hygiene
 Inadequate health care and education
 Lack of toilets
 Overcrowding and poor housing
 Poor nutrition and food preparation
      Source: U.S. Agency of bternuioml Development. Office of Housing «nd UriNm Program. Routing of
      Emironmtntol Risks in Bangkok. Thailand. December 1990.
 Step 4: Risk Characterization              j

   The final step of the health risk assessment process is risk characterization, which com-
 bines the information obtained from the hazard identification, dose-response, and expo-
. sure assessments to allow decision makers to evaluate and compare the relative risks posed

 by various environmental problems. Risk characterization synthesizes information on the
 severity, reversibility, individual or population exposures, .equity, and uncertainty of
 adverse health effects estimates by using the same criteria to evaluate all problem areas. By
 bringing this information to bear on the decision-making process, risk characterization
 forms an essential link between risk assessment and risk management, providing a frame-
 work to compare and rank different problem areas in a consistent and credible way. Once

 the problems are ranked, then decisions can be made about what to do about them in the
 next phase of a comparative risk project: risk management.
                                            I                      '-••',
 Analyzing Ecological Risk$            |

   The ecological component of die comparative risk process systematically applies ecolog-

 ical risk assessment principles to assess, evaluate, and rank die ecological risks associated

 with different environmental problems. Ecological risk analysis evaluates die likelihood of
 September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
adverse ecological effects occurring as a result of exposure by ecological receptors (e.g., a
group of white-tailed deer, or a community of interacting animal and plant species) to
stresson (e.g., lead, benzene, or road construction), and attempts to characterize the mag-
nitude of these impacts. Section 2.3 (Comparing and Assessing Ecological Risks) provides
information on these methods.
   The ecological methodology is conceptually similar to the human health methodology,
but differs in two distinct ways.  First, ecological risk assessment evaluates adverse effects
on a myriad of species' interactions and ecological processes, instead of assessing impacts
on only a single species (i.e., human beings). Second, ecological risk analyses assess non-
chemical or physical impacts, such as rivers that are dammed, wetlands that are drained,
forests that are cut, and wildlife habitats that are eliminated. Whereas human health
assessments focus on chemical stressors, ecosystems are often adversely affected by chemi-
cal and physical stressors.                                                            .
   Ecological risk analyses generally consist of four phases, which are described in the fol-
lowing sections.
Phase 1: Problem Formulation
   The first phase of a comparative ecological risk assessment involves a systematic plan-
ning process to review the list of environmental problem areas, to partition the project
area (e.g., a state) into a number of distinct ecological areas, and to select a set of criteria
to evaluate ecological  risks and rank problem areas. In addition, a preliminary examina-
tion of data needs and limitations may be necessary.
Phase 2: Analysis                             .
   In the second phase, the goal is to establish a causal link between the problem areas and
their ecological effects. Therefore, each problem area is broken down into a set of its most
important strcssors. The fate and transport of each stressor are then tracked through the
environment to determine its ecological effects. This requires knowledge about the toxici-
ty of stressors (for chemical stressors), the exposure or co-occurrence of ecological recep-
tors to stressors, and the response of ecological receptors to stressors.
   Where data are lacking or inadequate, professional judgment and consensus building
are needed to supplement gaps in data, sources of uncertainty, and a lack of knowledge
about complex ecological processes and interactions. For example, non-point source pollu-
tion poses risks to many surface-water bodies and coastal areas. One of the major stressors
associated with non-point source pollution is the use of nitrogen-based fertilizers in agri-
culture. The runoff of fertilizers from fields into streams, rivers, and coastal areas is an
important exposure pathway. The increases in turbidity and nutrient levels in streams and
rivers pose ecological  risks to fish habitats and breeding areas, shellfish beds, and to the
structure and function of plant communities. Existing data about these ecological effects
are gathered and supplemented with judgment and discussion during the analysis phase of
a comparative ecological risk assessment.
4.1-18                                                              September 195*3

                                   4.1 International Application of,the Comparative Risk Methodology
Phase 3: Risk Characterization             \                                  '
   The third phase of a comparative ecological risk assessment involves using the analyses
to characterize the risks posed to the environment by different problem areas. Risks,are
characterized in terms of the, evaluative criteria that are developed in die problem formula-
tion phase. Evaluative criteria include such factors as the area, severity, and reversibility of
impacts. Values can be assigned to each evaluative criterion using numerical scales or short
narrative descriptions. The raw information that provides the basis for assigning values to
the various evaluative criteria is often in the form of acres altered or stream miles degrad-
ed, changes in plant and animal community structure (i.e., biodiversity), and damages to
or declines in the populations of some species. Risk characterization also includes a sum-
mary of the assumptions and scientific uncertainties embedded in the analysis, and their
anticipated implications.                     ;    •
Phase 4: Comparison and Ranking of Rkks!
   The final phase of a comparative ecological risk assessment involves comparing the eco-
logical risks posed by different problem areas and ranking them. For ecample, habitat
alteration may pose greater ecological risks than solid waste, which might be placed with
other problem areas in a lower risk category. This is accomplished by considering the risks
to the environment in terms of all the evaluative criteria for each problem area. Thus, the
area, severity, and reversibility of impacts as well as the uncertainty of rfiese estimates are •,
considered and compared to other problem areas. Problem areas are then grouped into
several categories of risk using a consensus-building process. Professional judgment plays a
critical role, but the level of precision required is only as great as that needed to make very
rough relative comparisons, rather than absolute estimates, of risk.
   Ecological assessment methods are directly applicable worldwide. E>ata will often be
limited to a few ecosystems and must be supplemented with best professional judgment.
While the assessment methods used in the United States are transferable, data may not be
because species, ecosystems, and classification schemes are likely to be different. Analysts
should use local data first, then regional or national data, and finally, data from other
countries where conditions are as similar as possible. Alternatively, analysts can establish
systems for collecting ecological data, although use of existing data saves considerable time
and money. In the absence of complete data sets, ecological analyses am rely on more
hypothetical assessments of damages, knowledge of the physical and chemical stressors,
and their potential to cause adverse effects using available data.

Analyzing Quality-of-Life Impacts
   THe quality-of-iife analysis is composed of two parts: social impacts and economic
damages. These represent impacts to society that are not captured in the human health or
ecological analyses of a comparative risk study. Economic damages include the losses
resulting from diminished recreational opportunities, a drop in tourism due to environ-
mental degradation or the loss of wildlife, lost productivity and hospitilization costs to
people affected by pollution, and damages to crops or forest yields as a result of pollution.
Because the monetary values for the parameters were developed to reflect U.S. economic
September 1993

A Guidebook to Comparing Risks and Setting Environmental Priorities
conditions and values, analysts should carefully consider potential differences and reestab-
lish the estimates for parameters based on costs and values specific to the study region.
   Social damages can involve an array of concerns, such as negative impacts to peopled
sense of community, the aesthetic loss of beautiful places, the loss of cultural values due to
the disturbance of traditional practices or sacred places, and concern for the well-being of.
future generations as well as the inequity of impacts on different groups in society. Many
social concerns fundamental to the quality of life are difficult to monetize. But this is not
to say that they do not exist or are not important. In fact, it is widely recognized that these
issues are crucial to a comprehensive study of environmental risks.
   Issues surrounding social impacts are so country- and culture-specific that the methods
used in the U.S. studies can only serve as a model of American society. Thus, of all the
analytical methods used, the social impact analysis will require the most adjustment. Some
nations or cultures may wish to derive a whole new methodology. Studies in Africa could
use criteria that reflect family and tribal issues. In parts of Central Europe, the environ-
ment is in such a. poor state that people's concern is to improve the environment so that
their children may enjoy it. A study of eastern Africa's Masai might develop criteria that
include valuations for cows and eland, two species held in high regard in their culture.  In
the Hawaii study, cultural criteria included disruption of native Hawaiian life styles, popu-
lation growth and density, relaxing neighborhoods, access to mountains and the sea, and
shared community values and vision (Matsuoka et al. 1992).
   While there is no set procedure for conducting a quality-of-life analysis, the following
steps provide a framework from which a process can be established and used to measure
these types of social  and economic impacts^A more full treatment of each step can be
found in Section 2.4 of this document.                  •
Step 1: Identify' Impacts and Determine the Values of the Community
   The values of a community are the basis for an analysis of the impacts of environmental
problems on the quality of life. This step is important to assuring that the process has
broad support and represents public concerns accurately. Surveys, questionnaires, and
public  meetings are among the tools sometimes used to help reveal impacts and define
community  values.
Step 2: Identify and Define Evaluative Criteria
   Criteria can be derived from broadly shared public values and applied to each problem
area to determine how peoples' lives are adversely affected by environmental degradation.
These criteria can include both economic and social impacts, such as economic losses due
to lost tourism or recreational use, hospitalization costs and lost productivity, lost peace of
mind or sense of community caused by a development project or change in land use, and
concerns about the legacy of environmental damages left for future generations.
Step 3« Collect and Analyze Data on Impacts
   Once criteria have been selected, the challenge is to find a way to measure die damage
from each problem area. Projects may include both quantitative and non-quantitative
analysis. The point is to have a well-defined analytic framework and a consistent set of cri-

4.1-20                                                             September 1993

                                   4.1 International Application of the Comparative Risk Methodology
                                    - ' '   -.     '       '•           i       •"
 teria to apply to each problem area. Sources of data can include survey responses, public-
opinion polls and census data, anecdotal information, willingness-to-pay studies, direct-
 cost data, and noa^market data,              -i           '          ;    '
   An assessment of economic impacts should include as comprehensive a picture.as possi-
 ble of the nature and extent of present and anticipated economic impacts caused by envi-
 ronmental degradation. However, models to predict future impacts are often unavailable
 or are difficult to fit to existing data. Additionally, some aspects of economic impacts
 assessment (e.g., willingness-to-pay studies) are controversial, especially when results are
 presented to people who don't have an extensive knowledge of economics. Therefore,
 deciding which economic impacts to assess and methods to use, and whether to  explore
 future impacts, are among the early decisions that a quality-of-life work group will proba-
 bly make.                        .        •   .  "        ₯           i
 Step 4t Characterize Impacts for All Problem Areas
   The data are analyzed quantitatively, to provide an estimate of the relative severity of
 impacts from each problem area and the number of people affected.-Wherever possible,
 non-quantitative information is added to the description of the problem area. Consistent
 use of criteria and analytic techniques is important to the credibility of the assessment
 process.                              ' -   i  -                   ;
                                 '       r*   '                 "               •
 Step 5: Present Findings and Rank Problem .Areas for Quality-of-Life Impacts
   Quantitative and non-quantitative information is provided for each problem area. It
 can  be presented in charts,  matrices, or other devices for purposes of comparing  problem
 areas. The quality-of-life work group, or a policy-level committee advising the work
 group, uses the information presented to Develop a relative ranking of environmental
 problem areas for quality-of-life issues.       ;               .
   It is important to document the process and methods  used in a comparative risk pro-
 ject. This is particularly true for quality-of-life issues, which may require controversial ana-
 lytic methods or may involve values that are not universally shared. A clear statement of
 sources, quality, and extent of data; methods used; assumptions made; and degree of
 uncertainty in results will add to the credibility of assessments. Differing views and core
 values need to be clarified, respected^ and addressed. Where expert opinion is used in the
 absence of data, it should be clearly stated.     ;                            .
 Step 6: Analyze Future Environmental Conditions and Risk Management Considerations
   While risk management considerations should be kept separate from risk assessment, it
 is still important to anticipate and discuss future changes in environmental risk.  For the
 findings of a comparative risk project to remain relevant on a long-term basis, population
 growth and the values of the community regarding development chokes need to be con-
 sidered. For example, land-development choices to build housing, roads, and factories or
 to protect natural habitats and tourist attractions, will be affected  by demographic trends
 and will influence the future risks posed by environmental problems. Cleaner industrial
 processes, substitute chemicals, efficient agricultural processes, and other technological
 innovations may also affect the future risks associated with problem areas.
 September 1993

A Cuulebook to Comparing Risks and Setting Environmental Priorities
Assessing Other Damages
   Besides assessing the categories of economic and social effects described in Section
2.4.6, analysts maywant to develop simple measures and methods to assess other cate-
gories of damages not covered in diat section. For example, the economic and social costs
of relocating people who migrate from the countryside to the city is a major problem in
some countries. In addition to the obvious relocation costs and the burden that urban
migration is putting on the infrastructure and social services of many large cities, analysts
might develop surveys or other means of determining the perceived loss in the quality of
life for those people. To avoid confusion and achieve the best result, the quality-of-life
rankings could be presented as two rankings: one covering economic effects and the other,
social damages. This is beneficial if an attempt is being made to influence risk manage-
ment policies or strategies.         v         j                                      ,
   Analyzing the exposures of certain socioeconomic groups to contamination can be a
good indicator of the level of pollution, and its effects on people. Wherever possible, ana-
lyzing highly exposed or highly vulnerable socioeconomic groups separately can be
extremely helpful as an early warning of larger problems and in designing risk manage-
ment strategies to address the greatest risk reduction opportunities. By examining the
demographics of the affected populations, managers can determine whether low-income
or minority groups may be inequitably subjected to excessive environmental stresses. For
example, a native culture that revolves around fishing can be adversely affected economi-
cally and medically by damage to a fishery resource because of their reliance on the
resource to supplement their diets.
   The methods presented in Section 2.4 are designed to estimate the quality-of-life
impacts of environmental problems by examining each problem individually. The same
approach could be applied to different economic sectors of a country if one goal of a pro-
ject is to identify the types and amounts of pollution released to the environment by dif-
ferent economic sectors. This approach is discussed in Section 2.1. National income
accounts, which are economic bookkeeping systems that track national outputs of goods
and services, can provide information at a broader level and may be useful in characteriz-
ing the impacts of environmental problems on specific industries. It may be difficult to
attribute the impacts of or damages  to particular environmental problems, but national
accounts can- be used as a screening tool to identify the types of effects that warrant more
detailed analysis. Some countries are considering including measures of natural resource
depletion 'and other environmental externalities in their  national accounting systems
(World Bank 195)6).

   Identifying appropriate information sources, collecting data, and putting them in
usable form comprise one of the more important tasks of a comparative risk study. Early
and effective identification of information and collection of high-quality data will save
time and money. In addition to developing the necessary data, data collection and man-
4.1.22                                                    .        September 1993

                                   4.1 International Application of the Comparative
agement will benefit environmental managers by highlighting data.gaps, identifying future
data-collection priorities, and supporting future environmental efforts.

Minimum Data Requirements
   Two questions asked in the early stages of the project are: what kind of data does one
need, and how much? Some may hesitate to undertake a comparative risk project because
they believe that data are not sufficient. Comparative risk uses available data, and, where
data are inadequate or unavailable, best professional judgment. The overall objective is to
rank the relative risks posed by a comprehensive list of environmental problems, and rela-
tivc risk ranking—not pinpoint accuracy—is ail that is required.            .
   Ideally, the data would provide complete and accurate information on the human
health, ecological, and quality-of-life impacts of different problem areas. In reality, data are
often incomplete, inaccurate or out-qWate, tangential to one's needs, or in a difficult
form to use. Thus, the analysis is usually a blend of data and judgment.
   Data needs should reflect the project's objectives. For example, a study in a rural area
may focus data-collection and analysis efforts on information on  agricultural production,
pesticide use, natural-resource extraction rates, and rural-living practices. An analysis
focused on industrial activity in a metropolitan area may focus on the size, scale, and type
of manufacturing, energy use, effluent discharges, local climate conditions, and urban.
population risks.                                                  ,

Data Sources                             ;
   Sources of data for any comparative risk analysis arc highly dependent on the study area.
With the exceptions of toxicity data and possibly data on the release of industrial pollutants,
other countries will need to modify U.S. data, if U.S. data are used, as they are site-specific
and developed from environmental monitoring for regulatory compliance Therefore, they
reflect conditions  for that particular area and are not transferable to other locales.
   Relatively basic information can be assembled from a variety of sources to provide suffi-
cient information. Where data are absent or inadequate, then secondary or surrogate data
and best professional judgment can be used to fill in the gaps. These indirect sources of
data should be evaluated in light of other existing information. For example, risk estimates
of the impacts of non-point source pollution on human health can include investigating
exposure to pesticides through drinking water and bioaccumulation of pesticides in fish.
Data needs and sources for this problem are depicted in Exhibit 4.1.5.
September 1993         .  ..                 ,,                              4.1-23;

A Guidebook to Compiling Risks and Setting Environmental Priorities
                                   Exhibit 4.1.5:
                         Potential Data Needs and Sources
   Human health concerns associated with non-point source pollution include pesticides
   in drinking water and residues in fish. A variety of data are needed for risk estimates.

     Data Needs                      1 .     Possible Data Source
     Area under cultivation
     Types of pesticides used                 Ministry of Agriculture
     Pesticide used per acre
     Ambient concentration in water
     # of surface-water supplies             .  Ministry of Public Works
     # of users
     Fish consumption levels                 Ministry of Marine and Fisheries   ,
     Fish tissue levels
     Dose-Response                         Integrated Risk Information System
   In some cases, alternative data may provide«supplemental information that can support
the risk analysis. In the Bangkok study, analysts approached members of the municipality
with a list of ideal data. Subsequent discussions revealed that such data did not exist, but
alternative information describing the outcome'or driving force for a given health condi-
tion was available. While the new information led to a modification of the analysis, it still
provided the best available estimate of risk.
   The quality of the data is an important determinant of the quality of the analysis. The
more specific the data are to the problem being analyzed, the better the analysis. A hierar-
chy of data sources should be used to determine the best available information. The most
appropriate data will most likely be at the local and regional government levels. Where
such specific data are not available, national sources could be used, representing the sec-
ond tier in the hierarchy. International sources, which often consist of compilations of
national data, could be used in the absence of direct local, regional, or national sources.
Local and Regional Sources
   Data sources available at the local and regional levels may be the most valuable sources
of information, particularly if the study area encompasses only a portion of a country.
Local and regional sources might consist of municipal or district government organiza-
tions and research institutes, non-government organizations, industries, universities, and
hospitals. These sources should have the most reliable data on human health and ecologi-
cal exposures, natural-resource uses and damages, and disease incidence. In addition, local
organizations probably have specific data, on pollutant emissions and ambient concentra-
tions for different media (e.g., air, water).
   Data come in many forms, including unpublished data files, computer 'data bases and
models, industrial activity reports, university and industry studies, and scientific literature.
4.1-24                                                              September 1993

                                   4.1 Int£rna.uonal Application offhe Comfvraavt Risk
 The most useful resources for identifying these data will be project participants at the local
 and regional levels, who should be familiar with the specific data available for problem
 areas or should be able to identify those who are.                    ,
 National Sources'                         1
   Sources of information at the national level can include statistical yearbooks, environ-
 mental plans, national publications, economic studies, data bases, computer models, and
 industrial-activity reports. Such national sources can be particularly useful if the study area
 involves the whole country, rather than just a portion of it. Federal governments,  includ-
 ing environmental and economic ministries, agencies, institutes, and departments, are typ-
 ical repositories of such sources of information. The United Nations Environment
 Programme has identified National Focal Points (NFPs), which arc national institutions
 willing and able to provide environmental information upon request; these may be a use-
 ful starting point  at the national level (UNEP 1993). Non-government organizations may
 also be useful sources of information with a national focus.
 International Sources
   Although international agencies and organizations collect data that have a global per-
 spective, this can include data from different countries or for specific ecological regions.
 Technical staff may have knowledge of applicable international data sources. Coordinators
 for die NFP's U.N. mission officers and odier international representatives will also know
 what data are available and how to access the data.                     ,
                            >                                   i -       .
 ,  In some cases, proxy data will have to be used as a surrogate for data specific to the
 area. Using proxy environmental data may require revising the estimate on the basis of fac-
 tors specific to the study area. International data or generic loadings data, such as  the
 World Health Organizations Management and Control of the Environment, can fill many
 data gaps that occur at the local or national level (WHO 1989): However, using proxy
 data increase uncertainty and the chances for making erroneous assumptions about the
 area of study.           •  ,  .        '       j
   The U.N. Advisory Committee for the Coordination of Information Systems' Guide
 to U.N. Information Sources on the Environment provides a brief review of the statistical
 holdings of each U.N. agency and major private organizations (ACCI5! 1990). Also of
primary importance:                        j                  '-  ;
                                           i          •        •  ;           ''
   •   U.N: Environment Programme—UNEFs International Environmental Information
     System (INFOTERRA) is an.internatiqnal information exchange on all aspects of
     the environment (UNEP 1992). UNEP also compiles statistical data in its Global
     Environment Monitoring System (GEMS), This information is published periodi-
     cally in UNEP's Environmental Data Report (UNEP 1991). Covering a wide range
     of topics, it has meticulously noted source;, definitions, and data qualifications. All
     related GEMS information is being entered into the Global Resource Information
     Database, which compiles georeferenced environmental data for use on Geographic
     Information Systems. .Using both'INFOTERRA and GEMS, the respective contact
     can be identified through the U.N. Development Programme Minion Officer.
September 1993

A Guidebook So Comparing Risks anil Setting Environmental Priorittfi
   •  U.S. Agency of International Development—U.S. AID is working with most of its
      bilateral pinners in assessing their environmental problems. Environmental assess-
      ments and action plans developed as part of these programs can provide useful back-
      ground information.                                        •
   •  World Bank—In addition to a wide range of studies assessing environmental
      impacts, the Urban Environmental Indicators work of the World Bank has identified
      a key set of indicators related to impacts, causes, and policy responses.
   • ,  The World Health Organization—In addition to collecting data- and compiling health
      statistics indicating disease incidence by country, WHO has useful information on
      food-consumption patterns for different countries.                ••'.'.
   •  The Food and Agriculture Organization—In its annual Production Yearbook, FAO
      compiles statistics for different countries on agricultural, silviculture, and fisheries
      production and prices; food consumption; and land use (FAQ 1992).
   •  New on-line computer networks, such as INTERNET, provide access to data bases,
      publications, experts, and other environmental data sources.             .  •  .
Data Collection Issues                  -
   The availability of data for problem areas is likely to be highly variable. Sometimes,.
good  data may be readily available in a usable form. In other cases, substantial effort will
be required to obtain relevant data and to convert it into a usable form. Analysts may
encounter obstacles in collecting the data, such as die availability and accessibility of infor-
mation, the cost of acquiring data, the consistency and accuracy of data, and die time
needed to devote to the effort.
   U.S. comparative risk analyses are conducted using existing data.  In the process, some
of the areas identified may warrant additional data collection efforts for future projects.
However, if substantial data gaps  are identified early that will dearly affect the results of
the study dramatically, then collecting new data may be necessary. This section focuses on
collecting existing data, as this will be the approach used in most comparative risk studies.
Availability and Accessibility     .
   Because of a lack of reporting requirements in some countries, relevant data are often
not collected. Where data are collected, they may be privately held or restricted for use.
For example, industrial enterprises in countries with limited environmental regulations
may be unwilling to share information on processes and production for fear of pollution
control measures being imposed on them or that confidential information will be given to
a competitor. A spirit of cooperation should be developed between those individuals and
entities with information and knowledge useful to accomplish the project objectives. This
will facilitate data collection and analysis, improve the completeness and accuracy of the
study, and lay the groundwork for future activities.
4.1-26                •                                              September 1993

                                      International Application of the Comparative RisJt Methodology
 Cost of Data Acquisition
    Income instance, relevant data may be held by private organizations that require pay-
 ment for the information. The costs of obtaining data in these situations may make it dif-
 ficult to obtain it in a timely manner, particularly if resources are a constraining factor. For
 example, some of the organizations with useful data in Central Europe are being priva-
 tized and require payment for information.
    Project planners should allocate sufficient time for data collection activities. The
 amount of time needed depends largely on the size of the study area., the level of the over-
 all effort, and the degree of coordination among organizations managing different types of
 information. Data collection can be very time-consuming, particularly if multiple .organi-
 zations have overlapping responsibilities.   ,
 Validity and Accuracy                   .j     • •   '             .
  .  Analysts should be extremely careful in checking the validity and accuracy of the data
'they use. They should also thoroughly understand the origins of the data to-ensure consis-
 tency with assumptions used in the analysis. Understanding the source, the collection
 methods, and the original purpose of the data will help determine whether the informa-
 tion is useful and accurate. The sampling and analytical methods should be examined to
 determine whether their outputs are reliable and representative, especially if there are vari-
 ous conflicting sources of the same type of information, and to determine the best infor-
 mation source to use.                   '!   ' ..
    Often, the hardest task for the technical staff is dealing with limited data or old data, for
 example, though an area may have good population data, modifications may have to be
 made to estimate the  number of individuals exposed, because the pollution is distributed
 along natural boundaries,  not political. As data are modified or estimates are made, uncer-
 tainty increases. It is important that uncertainty from estimates .and data be documented,   j
 In the absence of data, best professional judgment can be used to arrive at risk estimates.

 RISK MANAGEMENT                 ;
    Risk management  is a decision-making process, in which the ranking results from the
 risk assessment process are integrated with economic, technical, social, and political con-
 siderations to generate a prioritized set of risk reduction or prevention strategies that will
 achieve environmental goals. Whereas risk assessment asks how bad the problem  is, risk
 management asks what can and should be done about it. The effectiveness of risk manage-
 ment strategies can be monitored and evaluated in terms of the progress made toward
 goals. These decisions represent the culmination of the comparative risk process.
    Because the objectives of comparative risk studies can be so varied, it is difficult to rec-
 ommend a single approach to risk management. To ensure success, risk managers must
. pay careful attention to the risk analysis results and consider other relevant criteria in
 order to identify the strategic options that will  achieve the greatest risk reduction  possible
 September 1993

    GuMxx>k to Comparing Ri,lu uU Setting Environmental Priarities
  with the resources available. The discussion of the risk management phase of a compara-
  tive risk project, as presented in Section 3, is applicable to international projects.

  Setting Environmental Goals .
    Environmental goals can serve a number of useful purposes. The process of setting
  goals can help managers determine which environmental problems are the most serious
  within the framework of a comprehensive'stratcgy. The process of setting goals also helps
  identify the types of environmental data needed, thereby focusing data collection and
  analysis activities. Goals can also provide a context for discussing joint, coordinated
  actions with other public, non-profit, and private organizations that can help clarify vari-
  ous roles that different panics can play. Finally, goals can also provide important bench-
  marks against which to measure the costs and benefits of various environmental strategies
  and efforts. Environmental goals can then be adjusted if the public determines that they
  are either too low in terms of the level of environmental  protection  sought or too high in
 terms of the cost to society. Once the resource demands for all goals are placed within the
 context  of available resources, it may become necessary to decide which goals are most
 important and which goals may have to be scaled down or implemented over a longer
 period of time.                                             '
    The overall objectives of the project will guide the risk management process: which par-
 ticipants are selected, which analytical activities are performed, and which criteria are con-
 sidered in making risk management decisions.  The resulting priorities can be used to allo-
 cate environmental resources within a country, restructure environmental regulatory or
 legal authorities, justify environmental loans from international organizations, and mobi- •
 lize public and private support for environmental programs. Such ambitious and far-
 reaching ob'jectives emphasize the importance of having consistent and committed politi-
 cal support for the effort, full participation by all stakeholders and decisions reached by
 consensus, public involvement and consent, and sufficient resources and time to adequate-
 ly conduct the process. Participation and cooperation of all major stakeholders is crucial to
 successful risk management.

 Establishing Risk Management Criteria
   Once a set of specific, measurable goals has been set, then it is necessary to establish
 risk reduction or prevention strategies to achieve thesis goals. In selecting risk management
 strategies, it is necessary to first decide what criteria will be used to evaluate possible risk
 management strategies. The criteria used to evaluate potential risk management strategies,,
 their relative importance, and the analytical tools used to incorporate tJiem in the process
 will vary, depending on the objectives of the process.  Each proposed strategy can then be
 evaluated against a common set of criteria to determine its feasibility and relative advan-
 tage compared to other strategies thai might be implemented.
   There is no'"correct" set of risk management criteria. Participants can consider criteria
that have been used in previous projects, add or substitute other criteria, and find a set of
evaluative criteria that work best for their project, For example, if one of the objectives of

4.1-28                                                             Septeraba 1993'

                                   4.1 Insemaaonal Application oftht Comparative Risk M
 a project is to build environmental institutions by developing and/or restructuring envi-
 ronmental research, environmental education, monitoring, and regulatory authorities,
 then existing statutory and regulatory authorities, institutional capabilities, the amount of
 risk reduction, cost, and ease and speed of implementation would be the most important
 and pertinent criteria to consider in this case. Some criteria that hs.ve been used in a num-
 ber of comparative risk projects include COST and cost-effectiveness,, technical feasibility,
 statutory authority, public support, equity, considerations, the ease and speed of imple-
 mentation, and the likelihood of the strategy being successful. These criteria are discussed.
 more fully in Section 3.1.                i                              '

 Selecting Strategies to Achieve Environmental Goals
   The purpose of this step is to select risk management strategies dirough an iterative
 process that gradually focuses on the most effective means of achieving environmental
 goals. Risk management decisions in international studies may have broader economic
 and social implications than those in past U.S. studies. These implications may require
 analysis of the effects of risk management strategies on the economy and in the'broader
 social context. Frequently,  countries link their environmental action plans to national pri-
 orities and economic policies. Within this large context, the risk management approach
 becomes far more important and influential.
   Opportunities and constraints'are different and should be maximized to their fullest
 potential.  In many countries, risk management strategies that impose costs on developing
 or struggling industries can be perceived as impeding economic growth. In such situa-
 tions, an analysis of how economic development  and  environmental protection can be
 maximized is advisable; however, the analysis should, consider the full costs of economic
 development, including negative externalities associated with industrial development. The
 analysis may also include an estimate of the social costs  and benefits to determine the  net
 social-welfare impacts. Risk management strategies may also incorporate an analysis of
 projected land use, population, and economic trends. The developed strategy should be
 compared to existing environmental strategies to  determine if they are better approaches
 to addressing the problem.                                    i
   To stan the process, work group members may propose risk reduction or preyention
 strategies from a "tool box" of risk management approaches. It may be very helpful to
 introduce work group members to a found-table  discussion of various risk management
 approaches and how they work. Different risk management approaches are depicted
 below, and a more full discussion of them cm be  found in Section 3- Proposed strategies
 can then be analyzed in terras of the criteria that have been selected! by the work group to
 evaluate the  merits of various strategies. The more promising strategies can then be sub-
jected to more rigorous analysis until consensus is reached on which ones to select for
 implementation. By focusing the analysis of strategies on environmental goals, it may  be
 more likely that common links between different problems will be identified and simulta-
 neously addressed.
September 1993

A Gv^ekook to Comparing Risii and Setting Environmental Priantiu
   Different risk management approaches include:
   •  Scientific and technological measures
   •  Provision of information to the public
   •  Market incentives and disincentives                •         ;   ,
   •  Conventional regulations   '
   •  Effective and innovative enforcement
   •  Interagency and international cooperation
   Different strategies and approaches exist within risk management options. Pollution-
 prevention strategies arc generally designed following the pollution-prevention hierarchy.
 At the top of the hierarchy, the most preferential option is source reduction and substitu-
 tion. The hierarchy then proceeds to the option of second choice, which is recycling, and
 on to treatment and  control, disposal, mitigation, and finally remediation as the option of
 last choice.
   Apart from the proposed risk management strategies, participants in this process may
 wish to consider broader institutional/political issues, such as:
   •  Resources required       •
   •  Relationships with key stakeholders              •  , .                 .,  •
   •  Key organizational policies
   •  Flexibility or adaptability of strategy
   •  Effects on other organizations     ^      , '
   •  Rule, policy, and statutory changes required

 Implementing Strategies and Monitoring the Results
   The purpose of this final step in the risk management process" is to implement rhe risk
 management strategics that are selected by the work group, and to monitor the results  to
 ascertain that progress is being made toward the environmental goals. While there are
 some ideas or "lessons learned" from past projects that can be described, it would be unre-
 alistic to assume that there are simple rules or advice that can be offered about how to
 select the best strategies. What seems most important is to acknowledge the complexity of
 the task.                         .   .                                  ;
    The process of selecting the most promising risk management strategies is a difficult
 process. Because so  many criteria are involved and goals,can range from reducing health
 risk to increasing environmental equity to spreading agency resources across an increasing
 number  of environmental challenges, no single set of comparisons is possible. No scientif-
 ic rule will tell work group members the relative importance of human health risks v. eco-
 logical risks. No weighting formula is likely to satisfy every  member's sense of the relative
 importance of the different criteria. In fact, the relative importance of each criterion is
  TTT7	"	'                                                September 1993
  4.1-30                     •                               ,           r

                                   4.1 IntrrruuiaTudApplication of she Comparative RisJt McthejJaloQ
 probably not something that remains constant across all environmental problems, and is
 likely to change depending on the problem under discussion.
   Structuring the decision-making process in a way that maximizes its integrity and rele-
 vance is crucial to the likelihood that the work group's decisions will actually be carried
 out. A vigorous and open discussion of the relative advantages and disadvantages of strate-
 gies among a diverse and knowledgeable work group will lend integrity to the process. The
 process will more likely be relevant and credible to those who have the ultimate authority
 to implement the strategies if it has included the right people, used appropriate criteria,
 and been reported clearly and persuasively.  !
   Once risk management strategies are selected, then tliey must be implemented and
 monitored over time to ensure that environmental conditions are changing in the direc-
 tion of the environmental goals that have been established. The risk, management work
 group should be prepared to present well-defined and credible strategies that will achieve
 broadly supported goals in a way that meets the publics interests and needs.
 Implementation is more likely to succeed if the strategies are pan of an overall strategic
 plan that firmly ties environmental policies to budgets and meaningful, measurable
 results. Monitoring thfe actual results of the strategies will help environmental managers
 and the public know if their efforts are working or if they need to be adjusted and revised.

 Alternative Views  of Strategy Development
   Risk management options need not always be developed within  the sectoral, organiza-
 tional, or media categories used during  the technical analysis. At times, such categoriza-
 tion can channel solutions along technical lines that ignore critical social, economic, and
 institutional factors. An alternative approach is to classify problems along a.spatial scale
 where appropriate economies of scale, governmental levels, and'social norms can be maxi-
mized to their fullest extent (see Tables  4.1.2 and 4.1:3).' This approach benefits lesser-
 developed and newly industrialized nations that need to consider hew to focus risk man-
 agement strategies activities at the appropriate level.
   This example, modified from the work of the UNDP/World Bank/UNGHS (Habitat)
 Urban Management'Program (forthcoming) presents, characteristic  problems of the urban
 environment in lesser-developed nations. In Table 4.1.1 problem areas are spatially distin-
 guished, as are key infrastructure and services.
   In Table 4.1.2, selected problems for a given spatial level are presented, along with pos-
sible solutions. The options presented descend.in order of preferred risk management
 options, following the EPAi Pollution Prevention Hierarchy.  In general, the most cost-
effective solutions are those at the top of the hierarchy. Administration and implementa-
tion for each activity best correspond to die associated government level. For example, in
the case of toxic dumps, municipalities are brat equipped to zone facilities in a common
area, license facilities, and monitor their compliance. Communities  would find it difficult
to achieve this goal, given their more narrow focus  and limited resources.
September 1993                          j                                   4.1-31

                A GuilelxxA to Comparing Risks and Setting Environmental Priorities..
                  In some cases, cross-spatial relationships can be identified, and joint activities can be
               developed. Municipal waste collection is an example of this. Community governments
               must oversee refuse collection, but municipalities are responsible for landfill management.
               Transboundary issues (i.e., the import and export'of pollution) must also be analyzed. For
               example, the source of water pollution can occur at almost any level and can have a broad
               range of impacts.
                                                                                   x..               .    t
                                             Table 4.1.2:
                          Spatial Scale of Urban Environmental Problems
                                       Spatial Scale of Impact Increasing
& Services
Water storage
On-site sanitation
Garbage storage
Stove ventilation
Lack of water
No sanitation
Disease vectors
Indoor air poll.
Piped water
Garbage coll.
Trash dumping
Natural disasters
                                                Metropolitan Area
Industrial parks
Treatment plants
Traffic congestion
Ambient air pollution
Toxic wastes
 Water sources
 Power plants
Water pollution
Loss of wetlands,
 and aquatic and
terrestrial habitats
Acid rain
Global warming
 ozone depletion
                                                                       September 1993

                                     4.1 liuern&aanal Afplieatum of At Comfontox RifJt Methodology •
                                          ;    Table 4.1 J:
                      Examples of Problems and Appropriate Types of Solutions
   Appropriate Level
       of Action ^

     Problem Area
  •   	•	7-fcr
  Solutions following
 Pollution Prevention

and Control


                Head of
               Indoor Air
Era eta-laden
Methane gas

Ni gilt soil
Sewage lines
   Toxic Wastes
 Waste minimization
 Efficient fuels

 Industrial recycling
 Use of grey water

Industrial waste-water

 Licensed hazardous
 waste facilities
 Hazardous wane
Region al/Pro vincial
 National or
                    Lose of Wetlands
                                   protection areas
 Water treatment
                   Add Rain
September 1993

X Guidetook to Comparing RaJu and Setting Environmental Priorities
Advisory Committee for the Coordination of Information Systems (ACCIS). ACCIS
Guide to United Nations Information Sources on the Environment, no.2. Geneva,
Switzerland. 1990.
Food and Agriculture Organization. Production Yearbook. Rome, Italy. 1992.                           , ,
Matsuoka, Jon, Davianna McGregor, and Luciano Minerbi.  Native Hawaiian and
Cultural Assessment. Phase 1: Problems/Assets Identification. Honolulu: University of
Hawaii at Manoa. December 1992.
United Nations Development Programme (UNDP)/United Nations Center for Human '
Settlements (UNCHS)/International Bank for Reconstruction and Development (IBRD).
Urban Management Program. "Environmental Profile of Katowice; Poland." Draft. 1991.
UNDP/World Bank/UNCHS. Urban Management Program. "Environment Strategies
for Cities: A Framework for Urban Environmental Planning and Management in
Developing Countries." Discussion Paper Series (forthcoming).                                       .
United Nations Environment Programme (UNEP). International Environmental  .
Information System QNfOTERRA). National Focal Points: Address Director? Nairobi,         -
Kenya. 1993.
UNEP.  INfOTEKSiPi. International Directory of Sources, 7th ed. Vols. A-C Nairobi,                  '       J
Kenya. 1992.                                                                                    "~
UNEP.  Environmental Data Report, 3d ed. Prepared by Basil Blackwell. Oxford, England.
1991.            1      .•           ...-'.                           '   .'.
U.S. Agency for International Development (AID).  Office of Housing and Urban
Programs. Ranking Environmental Risks in Bangkok, Thailand. >X'ashington, D.C.I 990.
 4,1.34                                                          September 1993



September 1993


                                                                     Appendix 1 ''
 AND RIVERS                        !
      1            •         '      •     -!     •••'.•'','•
   These are sources of pollution that discharge effluents into surfact waters through dis-
 crete conveyances such as pipes or outfalls. This problem area does not include publicly
 and privately owned municipal waste-water discharges. Pollutants of concern include total
 suspended solids; BOD; toxic organics, including pthalates and phenols; toxic inorganics
 such as heavy metals; and thermal pollution. Typical sources of discharge include metal
 finishing, pulp and paper processing, and iron and steel production. Facilities requiring
 permits under the National Pollution  Discharges Elimination System (NPDES) fall under
 this problem area.                 '     !

 AND RIVERS                        j                  .
   This problem area includes all constituents of the outfalls of publicly and privatdy
 owned treatment facilities. Both municipal sewage treatment outfalls and industrial dis-
 charges that flow through publicly operated treatment works are included in this problem
 area. Major contaminants include all those found  under Industrial Wastewater Discharges
 to Oceans, Lakes, and Rivers, plus ammonia, chlorination products, and nutrients.
 Combined Sewer Overflows (CSO's) are included in this problem aiea.

   As drinking water arrives at the tap, it may contain a wide variety of contaminants from
 both natural  and man-made sources, and point and non-point sources. Since many of the
 contaminants can be traced to other problem! areas, Drinking Water risk evaluation will
 involve much double-counting with those other problem areas (Industrial Waste-Water
 Discharges, POTW Discharges, Non-point Source Discharges, Storage Tanks, hazardous
and non-hazardous waste problem areas, etc.). Drinking Water is included as a problem
area because remediation/treatment options can occur either at the source of contamina-
tion (the other problem areas) or at the delivery system of the drinking water (treatment  or
switch to alternative supplies). Drinking Water includes both delivery systems that serve
25 or more people and are therefore covered by the Safe Drinking Water Act, and those
which serve fewer than 25 people and  are not so covered. Pollutants of concern include
disinfection byproducts, pesticides, inorganics (such as heavy metals), radionuclides, toxic
organics, fluoride from natural sources, and microbiological contaminants.

  This category includes pollutants that reach surface waters through sources other than
discrete conveyance for effluents. This includes runoff from agriculturali urban, indus-
trial, silvicultural, or undisturbed land. Possible pollutants are quite varied, although they
                                      I           •    .'    '    '     .".'.•
September 1993                                                 "    ~   Al-3

A Cut^feook to Comparing Riilcj ami Setting Environmental Priantus
include most of the constituents of the point source discharges to surface waters. Storm
water carries a large amount of solids, nutrients, and toxics. Other sources included in
this problem area-are: surface discharge of septic tanks, contaminated in-place sediments,
air deposition of pollutants (except for acids), and mine drainage. Pollutants not included
in this problem area arc acid deposition, solid waste disposal, hazardous waste sites
(RCRA & CERCLA), pesticide runoff, and physical impacts from discharges of dredge
and fill material.

  Damages arising from alterations in the quantity and flow patterns of ground water and
surface water are included in this problem area.  Such disturbances include channelization,
dam construction and operation, surface and ground-water withdrawals, construction and
flood control, irrigation distribution works, urban development, and the disposal and
runoff of dredge and fill materials. Physical changes to water flow and aquatic habitats are
included in this problem area, as is chemical contamination resulting, from physical .
changes (e.g. dredging of contaminated sediments).

  All forms of ground-water pollution, including sources not counted in other problem
areas, compose this problem area. These include fertilizer leaching, septic systems, road
salt, all injection wells, non-waste material stockpiles, pipelines, and irrigation  practices.
The list of possible contaminants is extensive and includes nutrients, toxic inorganics and
organics, oil and petroleum products, and microbes. As with drinking water, there is much
double-counting in this problem area. It "is included as a separate "special" problem area
like drinking water because a true understanding of the overall risb to this resource is par-
ticularly important, and because such an understanding is difficult if the risks are split
between many different problem areas.                  .

   Storage Tanks includes routine or chronic releases of petroleum products or other
chemicals from tanks that are above, on,  or underground; tanks owned by farmers; fuel oil
tanks of homeowners; or other storage units (such as barrels). Stored products  include
motor fuels, heating oils, solvents, and lubricants that have air emissions or can contami-
nate soil and ground water with such toxics as benzene, toluene, and xylene. This category
excludes hazardous waste tanks. Acute releases (explosions, tank collapse) are examined
under Accidental releases.

   This category generally includes the risks posed by active and inactive hazardous waste
sites regulated under the Resource Conservation and Recovery Act (RCRA). These sites
include RCRA open and closed landfills and surface impoundments, hazardous waste stor-
age tanks, hazardous waste burned in boilers and furnaces, hazardous waste incinerators,

                              =.                                   September 1993

                                                                       • Appendix I
 and associated solid waste management units.1 Seepage and routine releases from these
 sources contaminate soil, surface water, ground water, and pollute the air. Contamination
 resulting from waste transportation and current illegal disposal are also included. Radiation
 from hazardous "mixed waste" from RCRA facilities is included in this problem area.  •

   This category includes hazardous waste sites not covered by RCRA, but by Superrund.
 Most are inactive and abandoned. Sites can.be on the National -Priority  List (NPL), delet-
 ed from the NPL, candidates for the NPL, or simply be noted by the Federal Government
 or states as unmanaged locations containing hazardous waste. Sites m,ay contaminate
 ground or surface water, pollute the air, or directly expose humans and wildlife. There are
 many pollutants and mixtures of pollutants, including TCE, toluene, heavy metals, and
 PCB's. Radiation from hazardous "mixed waste" in abandoned/Superfund sites is. included
 in this problem area.                     i               '

               • •'                        '        .    •
   Municipal Solid Waste Sites includes  open and closed municipal landfills, municipal
 sludge and refuse incinerators, and municipal surface impoundments. These sources can
• contaminate ground and surface water and pollute the air with particulates, toxics, BOD,
 microbes, PCDFs, PBB's, and nutrients. Contamination may occur through routine
 releases, soil migration, or runoff. Most sites are regulated under Subtitle D. This category
 excludes active and inactive hazardous waste sites.
                                   \     i.    .          '' .   '
   Industrial Solid Waste Sites includes open and closed  industrial h-ndfills, industrial
 sludge and refuse incinerators, and industrial, surface impoundments. These sources can   ,
 contaminate ground and surface water and pollute the air with particulates, toxics, BOD,
 microbes, PCDFs, PBB's, and nutrients. Contamination may occur through routine
 releases, soil migration, or runoff. Most sites are regulated under Subtitle D. This category
 excludes active and inactive hazardous waste sites. Although the list of potential contami-
 nants is similar to municipal solid waste sites:, the concentrations, volumes, and mixes of
 pollutants found on rypcial sites are frequently Very different.
                        . -               i                 '             ' •
   ' Contaminants are accidentally released into the environment in a. variety of ways dur-
 ing transport or production. An industrial unit may explode and emit toxics into the air, a
 railroad tank car may turn over and spill toxics into surface water or roads, or a ship may
 run aground and spill oil or other cargo  into the environment. Damages to property, per-
 sonnel, and wildlife may occur from intense,, short term releases of toxic or flammable
 chemicals. Acids, PCB's, ammonia, pesticides, sodium hydroxide, and various petroleum
 products have been accidentally released.
 September 1993

A Giudeeoct to 'Comparing Ritlu anJ Setting Envirtmmenul Priorinei
   This problem area addresses risks arising from the application, runoff, and residues of
pesticides to humans and the environment. It includes risks to people applying agricultur-
al pesticides, including farm workers who mix, load, and apply them. Also included are
risks to the public and non-target plants and wildlife as a result of short range drift, over-
spray, and misuse. Some of the more dangerous substances include ethyl parathion,
paraquat, dinoseb, EPN, aldicarb, and diazinon. Disposal of mixed pesticide wastes has
resulted in the generation of highly toxic, largely unknown byproducts that have entered
the air and caused serious health problems. Suburban spraying of property, often done
with high pressure systems, can-result in contamination of neighboring property, residents,
pets, and livestock. Aside from direct exposure, additional pesticide risks stem from expo-
sure through ingestion of residues on foods eaten by humans and wildlife.
Bioaccumulation and food chain effects are also included in this category. Note that acci-
dental releases, ground-water contamination, and indoor air pollution from pesticides are
respectively included in the Accidental Releases, Aggregated Ground Water, and Indoor
Air problem areas.

   Sulfur Oxides and Nitrogen oxides cause a wide variety of primary and secondziry
 effects. Primary effects include health, visibility, and welfare impacts. A major secondary
 effect is acid deposition, which results from chemical transformation of oxides of sulfur
 and nitrogen,  producing acid rain, snow, and fog, as well as dry deposition. Acid deposi-
 tion alters the chemistry of affected aquatic and terrestrial ecosystems, damaging plant and
 animal life. Sources are a wide variety of industrial, commercial, and residential fuel and
 related combustion sources. This problem also includes visibility effects resulting from the
 long range transport of sulfates.

    Ozone and Carbon.Monoxide are major air pollutants in many areas, arising from both
 mobile and stationary sources. Damage to forests, crops, and human health can be severe.
 Note that,volatile organic compounds (VOCs) are critical precursors to ozone formation,
 but the direct effects of VOCs are included in the Air Toxics problem area. To the extent
 that VOCs result in ozone, those ozone effects are captured by this problem area.

    Air emissions of lead result from many industrial and commercial processes. This prob-
 lem area includes both direct exposure to airborne lead and exposure to deposited lead
 from airborne sources. It does not include exposure to lead from drinking-water delivery
 systems, or lead found in homes and buildings from leaded paint.
     -                                            /                September 1993

                                                                        Affeiutix 1
   Both total suspended paniculate and fine particulates/PM 10 arc included in this
 problem area. Major sources include motor vehicles, residential fuel burning, industrial
 and commercial processes, and in some cases strip or open pit mining.

   This problem area coven outdoor exposure to airborne hazardpus air pollutants from
 routine or continuous emissions from  point and non-point sources. Pollutants include
 asbestos, various toxic metals-(e.g., chromium, beryllium), organic gases (benzene, chlori-
 nated solvents), polycyclic aromatic hydrocarbons (PAHs, such as be:nzo(a)pyrene, primar-
 ily in paniculate form), gasoline vapors, incomplete combustion products, airborne V
 pathogens, cooling towers, and a variety of other volatile organic chemicals and toxics.
 The problem area covers exposure through both inhalation and air deposition of these pol-
 lutants to land areas. Runoffof deposited pollutants to surface waters is addressed in Non-
 point Sources. Major "sources include large industrial facilities, m'otor vehicles, chemical
 plants, commercial solvent users, and combustion sources. This catqgory excludes, to the
 extent possible, risks from pesticides, airborne lead, radioactive substances, chloroflouro-
 carbons, emissions from waste treatment, storage and disposal facilities, storage tanks, and
 indoor air toxicants.              -   •   .  j
                                        '  .    i '              '
   This category applies to exposure to accumulated indoor air'pollutants, except radon,
 primarily  from sources inside buildings and homes. These sources include unvented space
 heaters and gas ranges, foam insulation, pesticides, tobacco smoke, wood preservatives,
 fireplaces, cleaning solvents, and paints. The pollutants include tobacco smoke, asbestos,
-carbon dioxide, carbon monoxide, nitrogen oxides, lead, pesticides, suid numerous volatile
 organic chemicals such as benzene and formaldehyde. Occupational exposures are includ-
 ed, as is inhalation of contaminants volatilized from drinking water.

 INDOOR RADON                     I
   Radon  is a radioactive gas produced by the decay of radium, which occurs naturally in
 almost all  soil and rock. Risks occur when radon migrates into buildings through cracks or
 other openings in the foundation, water, or fuel pipes. The gas is trapped by dense" building
 materials and can accumulate to very high levels. When inhaled,, radon decay products can
 cause lung cancer. This category includes radon volatilized from domestic water use, and
 also indudes occupational exposures. The problem area does not include outdoor radon.

   Exposure to ionizing and non-ionizing radiation (beyond natural background) is
 included here. Sources of radiation included in this category are: radio frequencies (also
TV. transmitters, power lines, radar, microwive transmissions, and radiation from home
appliances and wiring); radiation from nuclear power operations; high-level radioactive

September 1993       ..                 i'                   \             Al-7

 A Guidebook so Comparing Rukj a.rui Setting Environmental Priorities
 waste (including spent reactor fuel) and low-level waste (including radiopharmaceuticals
 and laboratory clothing from hospitals involved in nuclear medicine, and tools used in
 cleaning up contaminated areas, etc.); and residual radioactivity (including the decommis-
 sioning of facilities, such as laboratories and power plants that use radioactive materials).
 Also included in this category are industrial processes, such as uranium mining and ,
 milling, and the mining of phosphate. Radiation resulting from nuclear accidents where  -
 radioactivity is released is included under Accidental Releases. Medical exposures (X-rays,
 radiation therapy) and exposure from ozone depletion arc not included.

   Sources affecting terrestrial ecosystems/habitats include both chemical and non-chemi-
 cal stress agents. Because chemical sources of degradation are addressed in other categories,
 this category includes physical modifications (such as mining and highway construction)
, and other sources of degradation (such as dumping of plastics and other litter) that affect
 terrestrial ecosystems/habitats. Effects on undisturbed lands/habitats that result from near-
 by degradation (habitat fragmentation, migration path blockage) are also included in this
 problem area. EPA often has no regulatory authority over sources of physical degradation,
 while in other cases it may be able to influence them through the NEPA/EIS process.
                     OPTIONAL PROBLEM AREAS
 ODOR AND NOISE POLLUTION                                .
   Although this problem area was not considered by the three previous regional projects,
 it was examined in Unfinished Business and covers a legitimate set of environmental con-
 cerns. If examined, regions should exclude all effects associated with the sources of the
 odors 'and noise, other than the odors and noise themselves. Noise from a construction
 site, for example would fall under this .problem area, while habitat destruction would be
 captured by Non-chemical' Degradation of Terrestrial Ecosystems/Habitats, and chemical
 runoff wo'uld  fall under Non-point Sources.

   The stratospheric ozone layer shields the earth's surface from harmful ultraviolet (UV-
 B) radiation. Releases of chloroflourocarbons (CFC's) and  nitrogen dioxide from industri-
 al processes and solid waste sites could significantly reduce the ozone layer. Although this
 is clearly a national and international problem, regional projects may wish to estimate
 their region's contribution to the problem, and analyze the effects of ozone depletion on
 their region.            •
 Al-8                                                            September 1993

                  APPENDIX!      ;
September 1993


                                                                         Appendix 1
   Atmospheric concentrations of carbon dioxide (CO2) are projected to increase over the
 next century-due to ari increase in fossil fuel combustion and a.decrease in tropical rain
 forests and other CO2 sinks. Higher levels of CO2 may raise climatic temperatures global-
 ly, raising the sea level and disrupting weather patterns. As with Stratospheric Ozone
 Depletion, this is clearly a national and international problem, but regional projects may
 wish to estimate their region's contribution to the problem and the likely effects of the
 problem on their regions.                |  .
September 1993



  Regional and State Planning Branch (RSPB)
  Debora Martin, Chief
  U.S. Environmental Protection Agency
  401 M Street, S.W. (PM-222A)     '
  Washington, D.C'20024
 " (202) 260-2700          :      •   •.

  Northeast Center for Comparative Risk (NCCR)
  Rick Minard, Director
  Ken Jones, Acting Director
  Vermont Law School"
 •P.O.Box 96
  Chelsea Street
  South Royalton, VT 05068   '
  (802) 763-8303

  Western Center for Comparative Risk (WGCR)
  Kate Kramer, Director
  P.O. Box 7576                   •      .    •
  Boulder, CO 80306
  (303) 499-8340                            ;

 EPA Region  I
 Katrina Kipp  ,                      ..,-,.
1 Planning Analysis and Grants Branch
 John E Kennedy Federal Building
 One Congress Street ,
 Boston, MA  02203   .
 (617) 565-3696 V

 EPA Region II                         ;
 Alice Jenik              •         '             •
 Policy and Program Integration Branch
 Jacob K. Javits Federal Building
 26 Federal Plaza .
 New York, NY 10278
 (212) 264-S296
 September 1993

A Guidtbook u Comparing Rists and Setting Eiannmmenal Pnari
EPA Region III
Lorna Rosenberg
841 Chestnut Building
Philadelphia, PA 19107

EPA Region IV
Thomas Nessmith
'Policy, Planning and Evaluation Branch
345 Courtland Street, N.E.
Atlanta, GA 30365
(404) 347-7109

EPA Region V
Lee Gorsky
Planning and Assessment Branch
77 West Jackson Boulevard
Chicago, IL 60604-3507,

EPA Region VI
Gerald Carney
Planning and Analysis Branch
1445 Ross Avenue 12th Floor Suite 12JDO
Dallas, TX 75202-2733

EPA Region VII            -
Richard Sumpter
Program Integration Branch
726 Minnesota Avenue
Kansas City, KS 66101

Don Patron
Strategic Integration Branch
Policy Office
999 18th Street Suite 500
 Denver, CO 80202-2405
September 1993

                                                                        Appendix 2
 EPA Region DC
 Michael Schulz
 Policy and Grants Branch
 75 Hawthorne Street
 San Francisco, CA 94105
 (415)714-1623               -

 EPA Region X                  •
 Joyce Crosson      -
 Policy, Planning and Evaluation Branch
 1200 Sixth Avenue                 :
 Seattle, WA 98101
 (206) 553-4029,  :

 Leap to 2000: Louisiana* Environmental Action Plan. Project Report:The Negotiated
 Single Text of the Public Advisory and Steering Committees. Louisiana Department of
 Environmental Quality. Baton Rouge, LA. November 30, 1991.                ,
             ...    -                    !                    ,       '          '  '
 •Environment 1991: Risks to Vermont and Vermonten. A report by the Public'Advisory
 Committee, The Strategy for Vermont's Third Century. Vermont Agency of Natural
 Resources. Waterbury, VT July 1991.        ~  .

 Reducing Risk: Setting Priorities and Strategies for Environmental Protection (SAB-EC-90-
 021). U.S. Environmental 'Protection Agency. Science Advisory Board. Washington, D.C.
 September 1990.                        i                .                  ".'.

 Toward 2010: An Environmental Action Agenda. Environment 2010: A joint projea of the
 State of Washington and the U.S. EPA. Washington Department of Ecology. Olympia
 WA, July 1990.        .              '   |   .   .

 Final Report: Colorado Environment 2000. Governors Citizen Advisory Committee.
 Colorado Environment 2000. Denver, CO. J!une 1990. ,
               "                        1                  '                   <
 Unfinished Business: A Comparative Assessment of Environmental Problems. U.S.      •   '
 Environmental Protection Agency. Washington, D.G. February 1987.
 The Comparative Risk Bulletin. A monthly newsletter published by the Northeast Center
 for Comparative Risk (NCCR). For subscriptions, call (802) 763-8303.
September 1993                         !..                                 A2-5