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OCR for page 37
2
Judgment in the
Risk Decision Process
A risk characterization is part of
a process that begins with the formulation of a problem the likelihood
of a harm-and ends with a decision. A risk characterization cannot
make up for deficiencies in other parts of the process; inversely, if the
other parts of the process are done well, it is far more likely that the risk
characterization will be both clear and useful.
Some of the analytical difficulties affecting risk characterization are
well known, such as the difficulty of determining an appropriate math-
ematical model for extrapolating from animal toxicological data to assess
the health consequences of human exposures and of comparing best esti-
mates of different risks when their uncertainty distributions differ in
shape or in variability (see, e.g., Finkel, 1990; National Research Council,
1994a). In this chapter we focus on other difficulties, often overlooked in
the extensive literature on risk analysis, that are equally important for
understanding and coping with risk. Many of these difficulties result
from judgments made at each step of the process that can undermine the
quality of risk characterization and, if they are unacceptable to some of
the interested and affected parties, become lightning rods for conflict.
Such difficulties tend to arise when the knowledge and perspectives of
these parties were not adequately incorporated into the process that led to
the judgments. Many of the difficulties can be prevented or reduced if the
process is recognized from the start to require both analysis and delibera-
tion and if it is organized to ensure that the judgments are informed by
appropriate deliberations.
37
OCR for page 38
38 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMOC~TIC SOCIETY
We consider in detail the steps of problem formulation, selecting op-
tions and outcomes to consider, and information gathering, as well as
synthesis, usually the major focus of risk characterization. We discuss
process design at the end of the chapter. We document the variety of
judgments made during each of these steps and some of the ways these
judgments can undermine understanding of risks and contribute to mis-
trust and public conflict about risk decisions. The chapter concludes with
a strategy for avoiding these outcomes by designing the analytic-delib-
erative Process so as to inform the kev judgments with the knowledge
1 J J (I
and perspectives of the range of decision participants.
Certainly, many risk characterizations and risk decision processes
have been appropriate for the decision at hand. However, as we note in
Chapter 1, some high-profile, controversial risk characterizations have
suffered from deficiencies, and sometimes the damage to decision mak-
ing has been significant. The deficiencies also threaten some lower-pro-
file risk characterizations.
PROBLEM FORMULATION
Perhaps the most basic difficulty with risk characterization is that the
people who will or should participate in the risk decision process fre-
quently have divergent perspectives on the decision at hand. Differences
of perspective cause problems because efforts to inform decisions neces-
sarily proceed from some implicit formulation of the problem: a risk
characterization that deals selectively with only one perspective on a prob-
lem will be inadequate for those with significantly different perspectives.
The Concept of Risk
~. ~. ~
Judgments pervade any understanding of risk (National Research
Council, 1994a). Some writers even question the idea that risk should be
conceptualized as a quantifiable physical reality (e.g., Douglas and
Wildavsky, 1982; Funtowicz and Ravetz, 1992; Krimsky and Golding,
1992; Otway, 1992; Pidgeon et al., 1992; Slovic, 1992; Watson, 1981;
Wynne, 1992~. They argue that the concept of risk helps people interpret
and cope with the dangers and uncertainties of life, including but not
limited to the prospect of physical harm, and that the concept is shaped
by human minds and cultures. That is, there are many different kinds
and qualities of dangers and many potentially useful ways of making
sense of them, and even though many of these are measurable in prin-
ciple, it is judgments and values that determine which ones are defined in
terms of risk and actually subjected to measurement.
The multidimensionality of risk and the many ways it can be viewed
OCR for page 39
JUDGMENT IN THE RISK DECISION PROCESS
39
help explain why risk characterizations sometimes lack authority for some
of the interested and affected parties to a decision, even when the charac-
terizations are supported by high-quality analysis. Individuals and
groups that do not share the judgments and assumptions about the prob-
lem formulation that underlie a risk characterization may well see the
information it provides as invalid, illegitimate, or not pertinent. They
may see the characterization as flawed because the underlying risk analy-
sis is based on controversial assumptions (often implicit) about which
perspectives are legitimate, which solutions are reasonable, and which
types of information are useful or relevant (Vaughan and Seifert, 1992~.
The history of risk analysis is filled with instances in which analysis,
at least to some of the parties, seemed to beg the question. One such case
is the risk analysis for the Yucca Mountain nuclear waste repository site,
mentioned in Chapter 1. Billions of dollars were spent on assessing the
quantitative and calculable risks associated with permanent disposal at
one site, when many people believe it would have been more productive
to assess the risks of temporary storage while engaging in a more thor-
ough debate on the merits of a permanent solution. Another example was
the comparison of coal and nuclear power generation in the 1970s that did
not consider slowing the growth of energy demand as one approach to
finding sufficient electric generating capacity to meet national needs.
Even the apparently straightforward act of defining the hazardous
pollutant to be characterized can embed important assumptions about the
nature of the problem. Should one consider narrow classes of compounds
such as dioxins, or broad classes such as the thousands of organochlorines
and assess chlorine as the relevant environmental risk? Such choices,
though they should be well informed by toxicology and other relevant
science, involve important acts of judgment that shape risk characteriza-
tion and even decision making (Fischhoff et al., 1981; O'Brien, 1995~. In
the chlorine example, the definition of the hazard is highly consequential
for the chemical industry and for proponents of pollution prevention; a
risk characterization based solely on either formulation might be unsatis-
factory to one of the interested and affected parties.
Missing Considerations
Three considerations that are often missing from the formulation of
risk problems have led to disputes about the subsequent risk character-
izations: fairness, prevention (of pollution or risk), and rights. Acknowl-
edging these concerns may lead to different (usually broader) problem
formulations than those that emerge from the ordinary routines of gov-
ernment agencies. The way such concerns are or are not addressed can
OCR for page 40
40 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMO C~TIC SOCIE~
directly affect choices about the options and outcomes to consider in char-
acterizing risk.
F.
alrness
For some interested and affected parties in risk decisions, managing
environmental risks has become a question of fairness, moral responsibil-
ity, and distributional equity (Beach, 1990; Bullard and Wright, 1992; Law-
less, 1977; Nelkin, 1989; Sandman, Weinstein, and Klotz, 1987; Vaughan
and Seifert, 1992~. An example from Chester, Pennsylvania, shows how
fairness issues can arise in risk characterization. Chester is an industrial
city with a declining population (now about 40,000) consisting largely of
low-income African Americans. It has become the site of numerous haz-
ardous facilities, including two oil refineries, a trash incinerator, some
Superfund sites, and an autoclave facility for infectious materials. When
a proposal arose to site a soil decontamination plant in Chester, the Penn-
sylvania Environmental Protection Agency proposed to do a risk assess-
ment of the plant project, examining its likely emissions and projecting
the incremental health risks to the local population on the basis of models
of exposures and dose-response relationships. But community represen-
tatives raised several other issues, one of which was the claim that adding
a new hazardous facility was unfair in a city where residents were al-
ready bearing more than their share of toxic exposures.
The city's questions led the regional office of the U.S. Environmental
Protection Agency (EPA) to agree to conduct an analysis based on a dif-
ferent problem formulation: a cumulative risk assessment that would
characterize pollution in Chester generally and identify the areas of high-
est risks. Such a risk analysis would focus serious scientific attention on
matters that are not considered in an incremental-risk analysis, including
the interactive effects of the hazards present in the city, the health effects
of the new hazard on a population whose health status may be compro-
mised by other exposures, and the comparison of overall pollution risks
in the exposed population with those in more affluent communities
nearby. These issues would not have been addressed in the original state-
proposed analysis. The city's position was that any risk characterization
that ignored these issues would be incomplete and inadequate in terms of
providing the information needed to make a major decision about public
health (personal communication, Gregory Schirm, 1994~.
Some fairness concerns, described in terms of "environmental jus-
tice" for minority and low-income populations, were given prominence
by Presidential Executive Order 12898, issued in February 1994. The
Executive Order recognized that federal agencies' risk analyses had not
previously made equity issues a routine part of the problem definition
OCR for page 41
JUDGMENT IN THE RISK DECISION PROCESS
41
and directed them to do so. Effective implementation of the order would
make the analysis of some aspects of fairness and equity an essential
input into risk characterization.
Prevention
Current debates about preventing pollution and risk also show clearly
how problem formulation shapes risk characterization and the entire risk
decision process. One proponent of pollution prevention has criticized
standard practice in risk analysis for asking the question, "Which envi-
ronmental problems can we ignore?" (because their risks are negligible),
rather than the question, "How can we avoid exposures to hazards?"
(O'Brien, 1995~. While both formulations omit the key question of cost,
the latter question invites consideration of a much wider range of possible
policy options (especially, pollution prevention). For many interested
and affected parties, a risk characterization that does not address preven-
tion could never provide the information they need to accept a risk deci-
sion, no matter how well the narrower problem is analyzed or character-
ized.
The controversy over control of the Mediterranean fruit fly, a major
pest to the $2 billion fruit and vegetable industry in California, illustrates,
among other things, how judgments about which aspects of risk to char-
acterize can obscure or highlight debates over pollution prevention. Much
of the Medfly debate and the associated risk analysis and characterization
in the early 1990s focused on estimates of risks to the health of residents
who might be exposed to the malathion spray. The debate centered on
dose-response questions and on the appropriateness of assumptions about
the behavior and therefore the exposure of residents who are warned
to stay indoors during an imminent spraying but who might not do so. It
is based on the formulation that the Medfly problem in California comes
from flies that have recently entered the state on infested fruit and that
spraying where flies have been seen will eradicate the problem (Califor-
nia Department of Food and Agriculture, 1994~.
Some critics argue that this formulation is incorrect because the flies
are now established as breeding populations in California and cannot be
eradicated by a spraying program (Carey, 1991; 1994~. They argue further
that the state has a vested interest in the isolated infestation assumption
because under it spraying might easily and cheaply convince potential
importers of California produce that it is fly free. If, however, the Medfly
is an established pest, malathion will not perform as claimed, and biologi-
cal pest control would become an alternative option worth considering.
Biological control would also avoid the projected human exposures to
malathion spray. The formulation of the problem as one of keeping an
OCR for page 42
42 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMO CRITIC SOCIETY
established pest population under control changes the questions for risk
analysis: the focus shifts to the risks of biological control approaches and
the comparative effectiveness of chemical and biological Medfly control;
it makes pollution prevention, in the form of nonchemical means of pest
control, a key policy option. If the Medfly problem has been incorrectly
formulated, much of the risk analysis and characterization has focused on
an incomplete set of options, and the needs of decision participants for
understanding have been poorly served.
Rights
Risk characterizations have also become controversial when they pay
little attention to issues of the rights of individuals or groups to control
their own lives. An example is the continuing debate about the fluorida-
tion of public water supplies. Advocates declare that this technique is a
safe and cost-effective method of improving people's dental health. Op-
ponents in addition to questioning the certainty of the scientific esti-
mates and raising the issues of increased risk of bone fractures in the
elderly and fluoridosis in those with poor kidney function speak about
individual rights and the undesirability of a public health policy that
eliminates individual choice in regard to exposure to a chemical agent
that has both benefits and risks (Lawless, 1977; Martin, 1989~.
Another example is the contentious debate about environmental "un-
funded mandates,', federal decisions that require states and localities to
spend their money on certain environmental and health projects, which
consequently reduces funds available for other projects. Many interested
and affected parties claim that they have rights to clean air and water and
that the federal government should protect these rights. Other parties,
chiefly state and local officials, complain that federal decisions that com-
pel their action, even if based on sound risk analyses, abrogate the right of
localities to use their funds to reduce risks in the most cost-effective ways.
While federal officials may have sponsored risk analyses to focus on re-
ducing the risks of environmental chemicals, a state public health depart-
ment or a mayor faces a different problem: a choice between reducing
risks to citizens from chemical residues in water or from birth defects,
traffic accidents, or violent crime. A risk characterization for water pollu-
tion alone may be quite beside the point for a local official confronting
such a choice.
SELECTION OF OPTIONS AND OUTCOMES
Problem formulation has practical implications for other steps in the
risk decision process. Among the most important is the way it shapes
OCR for page 43
JUDGMENT IN THE RISK DECISION PROCESS
43
choices about which options to consider and which possible adverse out-
comes to analyze- choices that are critical to the success of risk character-
ization.1 For a risk characterization to meet the needs of participants in a
decision, it must consider the range of plausible decision options. The
parties to a decision may not agree on which options are worth consider-
ing, but a risk characterization that does not consider an option that one
of the participants views as promising is likely to be seen as biased and
inadequate. The controversies over the Medfly and unfunded mandates
are examples. When problem definitions truncate the list of options too
severely, risk characterizations can be doomed to controversy long before
they are undertaken.
Organizations responsible for risk characterizations should make ef-
forts to identify the range of decision options that experts and the spec-
trum of interested and affected parties consider viable. Generating an
adequate list of options may be difficult. It demands familiarity with the
context of the decision, knowledge about the scientific and technical as-
pects of the possible risks, and, sometimes, creativity and imagination.
Also, it often demands that organizations listen to the interested and
affected parties. Although identifying the range of options is challenging,
it is a key to successful risk characterization.
Considering a sufficiently broad range of possible harms or losses is
equally important to risk characterization. Typically, analysis focuses on
only a few adverse outcomes such as cancer or birth defects in human
beings, loss of a species, or elimination of a habitat that are judged to be
the most serious of the possible harms. The analysis is sometimes further
restricted to the effects of exposure to a particular agent (a substance or
process), through a particular medium (e.g., air, water, or food intake).
Agencies may narrow the list of outcomes because they have narrow
responsibilities under law, because funds for analysis are limited, because
of political pressures, or for other reasons.
Consideration of only a few possible outcomes is usually justified on
the assumption that if a decision protects adequately against the selected
outcomes, it will also protect against the others, because environmental
and health hazards are strongly correlated. This assumption becomes
increasingly suspect as the range of outcomes of concern expands from
overt human health risks to effects on the immune system and related
systems (e.g., allergenicity); behavioral effects; psychological effects, such
1Selection of outcomes has sometimes been treated as a stage within problem formula-
tion: for example, the U.S. Environmental Protection Agency (1992a:12) refers to outcomes
as "ecologically based endpoints". We prefer to make a sharper conceptual distinction
between the two tasks.
OCR for page 44
44 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMOC~TIC SOCIETY
as anxiety and depression; ecological effects; and social, economic, and
ethical impacts. Some participants may doubt that protection against one
of these adverse outcomes is tantamount to protection against all. Some
of the nonmeasured outcomes may be more salient to some parties, and
they may argue that these other adverse outcomes should be subject to
analysis and characterization. Demands for such expansion of the out-
comes to be included can be especially meritorious when data are sparse
on certain outcomes, but the risks have nevertheless been dismissed on
the assumption that they are small enough to ignore.
An adequate risk characterization must address all the outcomes or
consequences of a hazardous situation that are reasonably important to
the relevant public officials and to the interested and affected parties to
the decision. Agencies should tailor their analyses to the decision to be
made, addressing the potential adverse outcomes most significant for
that decision.
Ecological Effects
One important class of nonhealth outcomes is harm to nonhuman
organisms and ecosystems. The EPA has taken the lead in developing a
conceptual framework for conducting ecological risk assessment (U.S.
Environmental Protection Agency, 1992a, 1992b, 1992c, 1992f, 1992g,
1993h) and is preparing guidelines for this activity. Analysis is difficult
because the effects may fall on individual animals or plants, on local
populations of a certain species, on ecosystems (thus affecting many spe-
cies), or on the survival of endangered species. At larger scales, effects on
the distribution of ecological communities across the landscape are cen-
tral to regional-scale ecosystem management (Grumbine, 1994; Harwell
et al., in press). There may be important ecological outcomes to consider
and characterize at each of these hierarchical levels of ecological systems
(Harwell et al., 1990~.
Ecological risk analysis requires an understanding of how the af-
fected ecosystem functions. There are numerous interrelationships among
taxa, across responses, and across organizational levels. In addition, some
of the most important effects may be indirect, operating through several
interrelationships. Many of these effects are inadequately understood,
difficult to measure, or laden with uncertainty (National Research Coun-
cil, 1993a). Some ecologists even dispute whether the concept of ecologi-
cal risk (or its inverse, ecological health) is useful for policy analysis (e.g.,
Lackey, 1994, 1995~. None of these scientific difficulties of estimation,
however, negate the importance for policy decisions of considering eco-
logical outcomes. Interested and affected parties may want to take ac-
count of ecological effects even if the level of scientific understanding of
OCR for page 45
JUDGMENT IN THE RISK DECISION PROCESS
45
them is poor. Qualitative assessments of relative ecological risks can
provide useful insights for environmental decision making (Harwell et
al., 19921. A critical need is to develop appropriate tools for assessing the
value of ecological systems, including both economic and noneconomic
(e.g., intrinsic) values.
Economic and Social Effects
Economic consequences are sometimes inextricable from the other
aspects of a risk. We are not referring here to the well-recognized eco-
nomic costs of regulating risks, but to the economic costs of the hazards
themselves. Many risk characterizations do not consider the full range of
adverse economic outcomes, even though they are important for decision
purposes and amenable to scientific analysis. A 1987 example from Brazil
is illustrative. When two men seeking scrap metal pried open a metal
capsule containing 100 grams of cesium 137, subsequent exposures to
neighbors and family resulted in 4 deaths and 50 cases of radioactive
contamination that required medical treatment. Described in this sense,
the accident appears to have been of local significance, without major
national or international impact. But that depiction fails to capture the
$20 million dollars in cleanup costs and the subsequent 50 percent drop in
the wholesale value of agricultural products from the Brazilian state in
which the accident occurred. Sales of manufactured goods were also
affected, despite the lack of plausible contamination (Freudenburg,1988~.
The incident illustrates that losses in terms of human health may not be
the only adverse outcomes of a hazardous situation that are worth charac-
terizing.
One important class of economic effects are those a given hazard has
on nearby property values (Greenberg, 1995; Gregory, Flynn, and Slovic,
1995~. A relationship between changes in property values and proximity
to hazardous waste sites has been repeatedly demonstrated (Greenberg
and Hughes, 1992, 1993; Schulze et al., 1994; Skaburskis, 1989~. For fami-
lies living near hazardous facilities, property value losses are sometimes a
significant factor that they want estimated and considered in a decision
process. Such information can provide guidance for making decisions
about the costs of risk remediation plans (McClelland et al., 1990~. An-
other kind of economic effect is the cost of insurance premiums and emer-
gency preparedness that flow directly from the possibility of an adverse
event (Freudenburg, 1988~. These costs are borne by the potentially af-
fected population regardless of whether they actually suffer from the
adverse event.
Risk characterizations typically do not address social effects, perhaps
because they are considered outside the purview of formal risk analysis.
OCR for page 46
46 UNDERSTANDING RISK: INFORMING DECISIONS INA DEMOC~TIC SOCIETY
Yet they are legitimate objects for risk characterization because partici-
pants in decisions need to understand them to make informed choices,
and many social effects are amenable to systematic analysis. Social effects
that may need to be considered in a risk decision include neighborhood
disruption and issues of social equity and stigma (Gregory, Flynn, and
Slovic, 1995~. Some risk decisions can significantly alter a community's
character. Neighbors often express fears that a hazardous facility will be
destructive to the community (Zeiss and Atwater, 1991~. It is not uncom-
mon to see these kinds of concerns taken seriously in negotiations about
citings, but they are not usually treated in conventional risk characteriza-
tions.
In part, what is at stake is community control (Elliot, 1984; Zeiss and
Atwater, 1991~. People are more willing to tolerate a risk if they feel they
have some control over the exposure (Slovic, 1987~. By the same token,
removing control from a community has social costs, even if the commu-
nity accepts a risk. For example, cleaning up a contaminated site near a
residential community is a disruptive process. Several studies have docu-
mented the tension between residents who want total removal of con-
tamination (usually younger families with children) and those who want
minimal disturbance and cost (usually older couples living on fixed in-
comes who have owned their homes for many years and have no children
living at home). The latter group sometimes opposes clean-ups that
would disrupt their lives (e.g., remove their gardens, demand temporary
evacuation, or involve high costs), while the former group finds the status
quo more disruptive (Claus, 1995; Fessenden-Raden et al., 1987; Levine,
1982~. Risk analyses could, but rarely do, explicitly consider the effects of
such kinds of neighborhood disruption. If the analyses implicitly set this
potential loss equal to zero, affected parties may find the risk character-
ization unsatisfactory.
Many affected parties in risk decisions expect the government to en-
deavor to achieve some fair balance between the risks a community or an
individual bears and the benefits received. Recently, this expectation has
been voiced as a concern for environmental justice for minority communi-
ties (Bullard and Wright, 1992; Greenberg, 1993~. There is evidence of
unequal distribution of noxious facilities between communities as a func-
tion of economic and racial or ethnic differences (Bullard, 1990; Commis-
sion for Racial Justice, 1987; U.S. Environmental Protection Agency, 1992h)
and of differential harm associated with these risk sources (Greenberg,
1995~. However, equity concerns had rarely been considered in conven-
tional risk assessments until Executive Order 12898, in 1994. To the extent
that this directive is implemented, agency risk characterizations will be
OCR for page 47
JUDGMENT IN THE RISK DECISION PROCESS
47
gin to provide information that will inform public deliberation on equity
issues.4
People sometimes hold negative associations for things, places, orga-
nizations, or people they connect to risks (Slovic, 1993b). Such stigma can
have a tangible economic impact: in 1989, concerns about the use of Alar
on apples led to nationwide decline in apple sales of over $100 million
(about 10%) after risk assessments were publicized that linked the sub-
stance to cancer in children (Rosen 1990~. Researchers have also identi-
fied the potential economic effects from stigma associated with the pro-
posal to construct a high-level radioactive waste facility in Yucca
Mountain, Nevada (Slovic, Layman, et al., 1991~. For many siting deci-
sions, the effects of stigma cannot be reduced by engineering and design
alone, but it may be possible to address them through compensation or
insurance (Fort, Rosenman, and Budd, 1993~. Although these effects or
potential losses from stigma are difficult to quantify or compensate
(Gregory, Flynn, and Slovic, 1995), they are nevertheless important to
consider.
Effects on Future Generations
Many risk decisions may impose risks on future generations that re-
quire a different kind of consideration from risks to people living today.
The high-level nuclear waste disposal facility planned for Yucca Moun-
tain, Nevada, is a striking example: releases of radioactive material from
this facility could cause harm thousands of years in the future. Such
situations present two questions for risk analysis: How can one be certain
that the risks to future generations are known? How can one represent
the interests of future generations in a current risk decision process?
The difficulty of the first question is illustrated well by the Yucca
Mountain controversy. As described in Chapter 1, a fundamental as-
sumption of U.S. and international policy on radioactive waste disposal
has been that safe, permanent disposal was the strategy most likely to
reduce the risks to future generations. But a 1993 technical review com-
mittee set up by the state of Nevada one of the interested and affected
parties questioned even that most basic assumption. Arguing that no
one today can predict what human beings might be able, or motivated, to
do at the Yucca Mountain site over the next 10,000 years, the Technical
Review Committee (1993:14) concluded that rather than protecting future
2Various formal analytical techniques exist for informing discussions about distributional
equity: all involve controversial techniques for valuing human lives (e.g., Zeckhauser,
1975; Anderson, 1988; Leigh, 1989; Ellis, 1993).
OCR for page 62
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OCR for page 64
64 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMOC~TIC SOCIETY
with the ways that risks tend to be characterized in quantitative risk
assessments (Slovic, Fischhoff, and Lichtenstein, 1979; The Royal Society
Study Group, 1992; Lindell and Malmfors, 1994~.
Conflicts over "risk" may reflect differences between specialists in
risk analysis and others on their definitions of the concept. In this light, it
is not surprising that citations of statistics about "actual risks" often do
little to change most people's attitudes and perceptions. Nonspecialists
factor complex, qualitative considerations into their estimates of risk, in-
cluding judgments about uncertainty, dread, catastrophic potential, con-
trollability, equity, and risk to future generations.
The legitimate, value-laden issues that underlie these multiple di-
mensions of risk need to be considered in risk policy decisions (Fischhoff,
Watson, and Hope, 1984~. For example: Is risk from cancer (a dread
disease) worse than risk from auto accidents (not so dreaded)? Is a risk
imposed on a child more serious than a risk accepted voluntarily by an
adult? Are the deaths of 50 passengers in separate automobile accidents
equivalent to the deaths of 50 passengers in one airplane crash? Is the risk
from an industrial emission worse if the facility is located in a neighbor-
hood that has a number of other hazardous facilities nearby? The difficult
questions multiply when outcomes other than human health and safety
are also considered. As noted in an earlier study (National Research
Council, 1989:51~:
Technological choices sometimes involve weighing the value of a river
vista, a small town style of living, a holy place, or the survival of an
endangered species, in addition to human health, against probable ben-
efits. Such matters are ultimately matters of values.
The fact that hazards differ dramatically In their attributes or charac-
teristics helps explain why certain technologies or activities, such as
nuclear power, evoke much more intense public opposition than others,
such as motorcycle riding, that cause many more fatalities. The implica-
tions of "risk perception" for synthesis have been well described in a
previous study (National Research Council, 1989:52~:
Those quantitative risk analyses that convert all types of human health
hazard to a single metric carry an implicit value-based assumption that
all deaths or shortenings of life are equivalent in terms of the impor-
tance of avoiding them. The risk perception research shows not only
that the equating of risks with different attributes is value laden, but
also that the values adopted by this practice differ from those held by
most people. For most people, deaths and injuries are not equal some
kinds or circumstances of harm are more to be avoided than others.
One need not conclude that quantitative risk analysis should weight the
risks to conform to majority values. But the research does suggest that it
is presumptuous for technical experts to act as if they know, without
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JUDGMENT IN THE RISK DECISION PROCESS
careful thought and analysis, the proper weights to use to equate one
type of hazard with another. When lay and expert values differ, reducing
different kinds of hazard to a common metric (such as number offatalities per
year) and presenting comparisons only on that metric have great potential to
produce misunderstanding and conflict and to engender mistrust of expertise.
65
This analysis is still pertinent with reference both to techniques for char-
acterizing relative risks in terms of expected deaths and to techniques that
compare hazards on a common monetary metric, such as contingent valu-
ation methods or various forms of cost-benefit analysis.
A number of risk analysts have sought technical solutions to the prob-
lem of taking qualitative aspects of risk into account. Generally, they
have proposed broadening risk analysis to incorporate one or more of the
various characteristics identified in studies of perceived risk: for example,
distinguishing between voluntary and involuntary activities in assessing
risk-benefit balances (Starr, 1969~; giving proportionally more weight to
large accidents than to numerous small accidents that cause the same
amount of damage or number of deaths (Wilson, 1975; Griesemeyer and
Okrent,1981~; and adjusting risk estimates to take into account the impor-
tance of various risk-perception characteristics (Rowe, 1977; Litai,
Lanning, and Rasmussen, 1983~. None of these proposals has yet been
developed to the point of application in actual risk assessments.
A related approach has successfully integrated several of the dimen-
sions of risk in a formal way and done so in real applications. This
approach has been developed by two Swiss analysts to aid decisions about
the safety of ammunition storage depots and transportation systems, in-
cluding the design of a high-speed railway in Germany (Bohnenblust and
Schneider, 1984~. The method characterizes the risk reduction in terms of
cost-effectiveness, and it attributes more value to reducing risks that are
involuntary, poorly understood, potentially catastrophic, and hard to con-
trol. Although this Swiss model has been applied to a number of impor-
tant decision problems, there is a need to align the model more closely
with recent research that has been done on social, cultural, and psycho-
logical factors (see, e.g., Krimsky and Golding, 1992~. This might be ac-
complished, at least in principle, by refining quantitative approaches to
risk analysis (see Chapter 4~; it might also be achieved qualitatively
through deliberative processes (see Chapters 3 and 5~.
Another way to incorporate some of these dimensions into risk char-
acterizations is to apply multiattribute utility analysis (e.g., von Winter-
feldt and Edwards, 1986; Fischhoff, Watson, and Hope, 1984; Gregory,
Lichtenstein, and Slovic, 1993; Brody and Rosen, 1994; see also Appendix
A). In this technique, individuals identify value dimensions, attributes,
or outcomes that are important to them, assign relative weights to them,
and evaluate the outcomes identified by risk analysis (or a set of policy
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66 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMOCRATIC SOCIETY
options) on each attribute. Multiattribute utility analysis allows individu-
als to compare options that yield different packages of risks and benefits.
It allows for evaluations to be explicitly subjective: individuals can, for
example, assign a numerical value to a quality such as "incidental en-
counters with neighbors." But it does not, by itself, solve the problem of
providing risk estimates for populations because there is no acceptable
formula for aggregating individuals' evaluations. Should each indivi-
dual's evaluation have equal weight, or should those who might bear the
risk have a greater weight? This problem of estimating risks for whole
groups when the risks are of various kinds pushes the limits of analysis.
(In Chapter 4 we discuss the strategy of using analytical techniques to
reduce the dimensionality of risk. In Chapter 5 we discuss the alternative
strategy of combining deliberative processes with analysis to help the
participants in decisions develop working understandings of multi-
attribute risks.)
The Meaning of Risk Estimates
Separable from the technical questions about how best to estimate the
risk of a particular agent with respect to a particular outcome is the ques-
tion of what the risk estimate means, or should mean, to participants in
risk decisions. Risk characterizations often fail because they attribute
meaning to scientific estimates in ways that mislead participants in the
risk decision process or that are incomprehensible to them. This section
discusses several such sources of failure: in the treatment of uncertainty,
in inferences about which populations will be affected, and in inferences
about how a risk estimate should be interpreted in light of other risks to
which a population is exposed.
Uncertainty
Risk characterizations often give misleading information about un-
certainty in several ways. They may give the impression of more scien-
tific certainty or unanimity than exists (or of more uncertainty or dissen-
sion). They may suggest that uncertainty is a matter of measurement
when in fact it is a matter of disagreement about whether a particular
theory applies or differences in judgment about how to infer something
that is unknown from something that is known. And they may give the
impression that certain risks do not exist when in fact they have not been
analyzed.
Civil engineers, public health professionals' and others often take
account of uncertainty by a strategy of "conservatism." This means that
they recommend decisions or actions that leave a margin for error that is
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JUDGMENT IN THE RISK DECISION PROCESS
67
intended to protect the public if the actual risk turns out to be greater than
they predict. It is often argued that risk analysts should instead present
their best available estimate to decision makers, along with an explicit
characterization of its uncertainty, and allow the decision makers to de-
cide explicitly how much margin of safety to allow.4 Either approach
embodies a value choice about the best way to characterize risk and pro-
tect public health and safety, and there is no scientific technique for deter-
mining which approach is preferable (National Research Council, 1994a).
There is strong agreement that risk analysts should explicitly summa-
rize uncertainty, and there are methods for doing so (e.g., Morgan and
Henrion, 1990~. But despite the admonitions of officials in some govern-
ment agencies (Habicht, 1992; Browner, 1995) and the recommendations
of outside panels (e.g., National Research Council, 1994a), many risk char-
acterizations still present point estimates of risk, representing these as
upper-bound estimates and providing little or no analysis of the extent of
overestimation. In spite of the obvious shortcomings of point estimates
and the efforts to develop alternative ways of describing uncertainty-
such as with probability distributions or scenario approaches no alter-
native has gained widespread recognition as acceptable and practical
within EPA and other regulatory agencies. It is difficult to characterize
what is known about uncertainty without making the risk appear either
larger or smaller than analysts believe it to be (see, e.g., Johnson and
Slovic, 1995~. And the difficulties are not yet yielding to analysis: the
more that characterizing uncertainty is debated as an analytical problem,
the more complex it appears to be (see, e.g., Finkel, 1990; National Re-
search Council, 1994a:Chapter 9~.
Characterizing uncertainty analytically puts risk analysts on the horns
of a dilemma: simple characterizations are likely to give an erroneous
impression of the extent of uncertainty, but more careful and elaborate
characterizations may be incomprehensible to nonspecialists and so un-
usable by decision makers and some other participants. Like the problem
of finding a single, unbiased summary of accepted scientific knowledge,
the problem of summarizing uncertainty may have no technical solution.
We believe, however, that a solution might be found in the processes that
lead to a risk decision, processes that combine iterative deliberation and
analysis and provide participants with enough understanding of uncer-
tainty to appreciate where scientists agree and where they disagree. (The
last section of this chapter outlines key issues in process design; Chapter
4 presents a more detailed discussion of understanding uncertainty.)
4For an illuminating exchange of views on the "conservatism" issue, see Finkel (1994)
and McClellan and North (1994).
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68 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMOCRATIC SOCIETY
Specific Populations
The question of who is at risk is important both for decision makers
and the persons whose health and safety is of concern (Vaughan and
Seifert, 1992; see also Konheim, 1988; Nelkin, 1989~. In presenting aggre-
gate risk estimates to community residents who are concerned about a
hazard, officials often fail to answer the important question for many
interested and affected parties: "What does this mean for me or my
family?" (e.g., Sharlin, 1986~. When confronted with statistical risk esti-
mates, people often seek to reframe the question in terms of personal risk
(Plough and Krimsky, 1987; Siegel and Gibson, 1988~- an issue not ad-
dressed by the aggregate numbers. If a risk characterization does not
address such questions, both it and the analysis behind it may be discred-
ited by participants in the decision process. If it does address them,
different ways of framing the same information can create different un-
derstandings.
Such failings often arise when a risk characterization assumes that
estimates of risks to one population are sufficient to answer risk questions
about what may be a different population. For example, the 1989 contro-
versy over the use of Alar on apples centered on the risks to children, who
drink more apple juice than adults, but the standard was set on the as-
sumption that an adult male weighing 70 kilograms was an adequate
surrogate for everyone (lasanoff,1987~. The risk reduction expected from
vaccination programs is usually presented for the entire population al-
though rural children, who live far from treatment centers, may not re-
ceive as much benefit as other children because vaccination programs
may not reach them. Migrant farm workers and their families may be
inadequately protected against workplace risks because standards are
based on exposure under very different working conditions (Vaughan,
1993a).
To adequately summarize risks to some populations may require be-
havioral analyses as well as the traditional analyses of exposure and sen-
sitivity. For example, different groups of farm workers who are exposed
to pesticides vary in their ability to understand warning materials and in
their propensity to take self-protective action when given the opportunity
(Vaughan, 1993a). Knowledge about reading ability and the psychologi-
cal factors underlying self-protective behaviors are not usually incorpo-
rated in risk characterizations although they can obviously affect both the
risks to exposed individuals and the effectiveness of options to reduce
those risks. Thus, a risk characterization that fails to carefully consider
which populations the estimate is for may be inadequate to inform deci
. . .
slon magma.
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JUDGMENT IN THE RISK DECISION PROCESS
Multiple Exposures
69
Risk analyses for multiple exposures are often based on the assump-
tion that risk from genotoxic carcinogens are additive and that non-cancer
risks are not, unless the agents operate by similar mechanisms. The de-
gree to which this assumption holds is subject to debate because of the
limited data available to address it. It is even less clear how well the
assumption may apply for combinations of biological, chemical, and phy-
sical risks to an ecosystem. EPA has considered multiple chemical eco-
logical risks, but only at certain sites and within narrow bands. Although
the agency also recognizes physical hazards and those that arise from
management practices (U.S. Environmental Protection Agency, 1992a), it
has not considered their possible interactions. For humansr evidence of
serious drug interactions suggests that even with chemical hazards there
are some instances in which the assumption of additivity may be ques-
tionable. Increasing concerns about synergistic effects warrant careful
consideration of how to address them in risk characterizations.
A related issue is the treatment of past exposures or the past health
conditions of some of the population at risk. This issue may arise as one
of health (e.g., the possibility that past exposures have synergistic effects
with present ones) or of equity. As the Chester, Pennsylvania, case sug-
gests, residents of an industrial community who believe that they have
already had more than their share of exposure to chemical risks may
demand on equity grounds that past exposures be considered as part of
the risk characterization.
Communication
The success of a risk characterization depends on its effective delivery
to the participants in a risk decision. Typically, not all participants will
understand a risk message in the same manner. Analogies are often used
to make risk summaries more understandable, but analogies are usually
very specific and sometimes depend on culture, status, age, gender, and
other characteristics for their interpretation. If the manner in which the
risk message will be interpreted by different groups or participants is not
considered, uneven risk protection across groups could result (Vaughan,
1993a, 1995~. Another even more fundamental problem is that of compre-
hension. Non-English-speaking people obviously get no benefit from a
risk characterization in English. Messages prepared in written form will
be ignored by people who cannot read or who are used to receiving
information in other forms.
The history of interaction between an organization that is presenting
a risk characterization and the interested and affected parties can be an
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70 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMOC~TIC SOCIETY
other source of communication problems (e.g., Krimsky and Plough,
1988~. A party that has had unsatisfactory experiences with that organi-
zation or that issue may simply be unreceptive to new information from
that source. For example, in a decision-making process to permit experi-
mental land application of sewage sludge on farmland, an elaborate pub-
lic involvement process collapsed partly because the same community
had been involved in a landfill siting controversy just one year earlier. A
widespread belief that the community was targeted as a "dumping
ground" overpowered any positive reaction to the public involvement
plans. People in the community organized against the new proposal
partly because of ill feelings toward the state regulatory agency (Renn et
al., 1991~.
CONCLUSION: THE IMPORTANCE OF PROCESS DESIGN
This chapter surveys the variety of judgments made sometimes,
without careful consideration in the course of analyzing and character-
izing risk that can become lightning rods for controversy. They become
problematic when they conflict with the judgments of some of the inter-
ested and affected parties to a decision, so that the resulting risk charac-
terization does not address these parties' needs. The best way to prevent
such problems, we believe, is not to call all such judgments into question
in every decision process. Doing this would make risk analysis and char-
acterization inordinately complex and resource intensive. We believe the
best preventive is to devise analytic-deliberative processes that will pay
appropriate attention to the judgments involved in problem formulation
and the other tasks, inform these judgments with the best available knowl-
edge and the perspectives of the spectrum of decision participants, and
thus guide risk characterizations toward addressing the needs of the deci
slon.
When understandings of risk depend on potentially controversial
judgments, it seems prudent to involve those who are likely to be affected
by the decisions that rely on those judgments. If, for instance, there are
many scientifically defensible ways of counting deaths and if the choice
has serious implications for the concerns of some of the interested and
affected parties, it makes sense to involve those parties in selecting the
measures of death that will be used to characterize risk. Organizations
responsible for characterizing risk should anticipate the value-based judg-
ments that are likely to become contentious in the context of a particular
risk characterization and consider putting them on the agenda for the
analytic-deliberative process.
We emphasize strongly that improved risk characterization based on
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JUDGMENT IN THE RISK DECISION PROCESS
71
a better designed process will not eliminate conflict about risk. The best it
can hope to do is to eliminate or reduce those conflicts that are based on
misunderstandings, mistrust, miscommunication, inadvertent neglect of
a point of view, and the like. It might be said that although good practice
does not predictably lessen conflict, bad practice predictably increases it.
Designing an analytic-deliberative process involves many choices.
Who should be involved in the tasks that support risk characterization,
beginning with problem formulation? In what ways and through what
procedures should they be involved? At what points in the process should
they be involved? Under what conditions should past assumptions, con-
clusions, or decisions be reconsidered? These choices can affect the ulti-
mate content of a risk characterization, the ways participants in a decision
understand the risks, and acceptance of the process.
Federal agency officials with a legislative mandate to protect the pub-
lic against dangerous exposures to a toxic substance commonly respond
to preliminary evidence of a possible hazard by directing toxicologists,
epidemiologists, and other technical experts on the hazard to estimate the
health risks associated with the substance. The process involves these
experts, agency officials and policy makers, attendees at any required
public hearings (whose ideas may or may not be given serious consider-
ation), and any legislators and interest groups that know about the pend-
ing decision and are able to gain access to the process. This standard
process often leads to objections from interested and affected parties that
they have been disenfranchised, that their ideas have been ignored, that
their concerns have not been taken seriously, that the risk analysis was
incomplete or irrelevant, that the analyses are so complex and arcane that
they cannot participate meaningfully, and so forth in short, serious dis-
affection with the process and the resulting risk characterization.
Such outcomes have led many observers to recommend increased
public involvement in risk decision making, better two-way communica-
tion between agencies and interested and affected parties, involvement of
these parties early in the decision process, and other changes that would
make risk decision making processes more broadly participatory (e.g.,
Kunreuther, Fitzgerald, and Aarts, 1993; Leroy and Nadler, 1993; Slovic,
1993a; National Research Council, 1994b). We agree that more complete
involvement of interested and affected parties in risk characterization is
often essential for improving the process. It can also be essential for
arriving at sound analyses. We note here some key principles of increas-
ing meaningful participation in risk characterization that are developed
in more detail in the next several chapters:
· give explicit attention to the design of the process that informs risk
. . .
clec~s~ons;
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72 UNDERSTANDING RISK: INFORMING DECISIONS IN A DEMOCRATIC SOCIETY
· solicit and seriously consider input from the interested and af-
fected parties as appropriate at various points in the process leading to
risk characterizations; and
· plan for iteration in the decision process, that is, for reconsidering
past assumptions, conclusions, and process-related decisions on the basis
of new data and changes in the decision situation.
We reiterate that risk characterization is more than a synthesis of
information developed by analytical techniques. Analysis has inherent
limitations in the face of the multidimensional and value-laden nature of
many risk decisions. The success of risk characterization depends not
only on doing and describing analysis well, but also on choosing analyses
that address the needs of decision participants and on making the choice
through a process that those parties trust. Organizations responsible for
characterizing risks should plan to blend analysis with deliberative pro-
cesses that clarify the concerns of interested and affected parties, help
prevent avoidable errors, offer a balanced and nuanced understanding of
the state of knowledge, and ensure adequately broad participation for a
given risk decision.
Representative terms from entire chapter:
risk decision
