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OCR for page 1
PERSPECTIVES ON RISK AND DECISION MAKING
When people say they must make a decision involving
risk, they often mean that the decision involves the
possibility of an adverse consequence. This report does
not deal with risk and decision making so broadly de-
fined, since almost every important decision in life
entails the possibility of an adverse consequence. To
narrow its task, the committee concentrated on those
decisions involving the possibility of adverse effects
for human health, safety, and the environment. This
narrowing does not reflect a belief that other types of
risks are less important--certainly the personal risks
in a career choice or the economic risks faced by people
in business are no less important. The focus reflects
the committee's expertise and, more important, a growing
public awareness of and concern about adverse conse-
quences to human health, safety, and the environment.
INCREASED LONGEVITY AND RISING PUBLIC CONCERN ABOUT RISK
The increases in average life expectancies for Americans
have not lessened their concern with risks and may even
have increased it. The evidence for changing mortality
and morbidity is worth examining briefly as a base for
OCR for page 2
2
gauging actual risks; further exploration of possible
reasons why concerns with risk have not abated may im-
prove understanding of the perceptions of risk.
The first sentence of a recent report (U.S. Surgeon
General, 1979) proclaimed that "the health of the Ameri
can people has never been better." ~'
-Lee surgeon general
documents improvement in many indices of illness, non-
fatal conditions, and mortality. We would like to
emphasize primarily the progress made against mortality,
since, in the absence of a comprehensive statistical
measure of risk, the single best indicator is perhaps
that provided by mortality statistics. The decline in
U.S. mortality rates since the turn of the century has
been steady and, on a cumulative basis, dramatic.
Life expectancy at birth has increased in the United
States from 47 years in 1900 to 74 years in 1979. The
age-adjusted death rate has fallen by two-thirds, from
18 per 1,000 in 1900 to under 6 per 1,000 in 1979. The
probability of "early" death--death before age 65--has
declined from over 60 percent at 1900 mortality rates to
under 25 percent at 1979 rates.
Mortality reductions in the 1970s have been espe-
cially impressive. For example, in the United States
the likelihood that a person age 65 would live at least
another decade has increased by 14 percentage points
from 1900 to 1970 (from 55 to 69 percent) and then by
another 5 percentage points by 1979 (to 74 percent). In
1979, the age-adjusted death rate at all ages was 18
percent lower than it was 9 years earlier. Similar im-
provements have occurred in other countries as well,
including dramatic ones in the less developed countries
considered as a group.
According to one poll (Louis Barris and Associates,
1980) most Americans believe life is getting riskier:
78 percent of the public surveyed agreed that "people
are subject to more risk today than they were twenty
years ago" (p. 9~; only 6 percent thought there was less
risk. Furthermore, 55 percent felt that "the risks to
society stemming from various scientific and technologi-
cal advances will be somewhat greater 20 years from now
than they are today" (p. 10), as opposed to only 18 per-
cent who felt that the risks will be somewhat less.
The degree of concern about risk has increased
sharply since about 1960. For example:
OCR for page 3
3
.
.
.
.
.
.
.
The enactment of more than 30 major laws by the
U.S. Congress from 1965 to 1980 (and numerous
laws by state legislatures) aimed at coping
with occupational, consumer product, environ
mental, transportation, and other sources of
risks;
The establishment or strengthening of at least
a dozen regulatory agencies with broad legal
authority and rising budgets throughout the
1970s;
The growth of litigation related to health,
safety, and environmental risks in the 1970s in
both the tort-liability system and the arena of
judicial review of agency decision making;
The creation and growth of numerous public
interest groups concerned with health, safety,
and environmental risks, a movement that has
significantly changed the politics of risk and
the politics of regulation;
The emergence of various forms of business
sponsored efforts to improve risk management by
the private sector, to publicize these efforts,
and to coordinate them with those being taken
by local, state, and federal governments (for
examples of increasing corporate efforts to
control risks, see U.S. Department of Commerce,
1980~;
The expanded media coverage of scientific find
ings about risks, corporate risk .anagement
activities, and political activity related to
risk;
m e increase in funding for health, safety, and
environmental research and the emergence of a
relatively new field of "risk analysis."
SOME POSSIBLE INTERPRETATIONS
Multiple hypotheses have been proposed for the apparent
contradiction between increased longevity and increased
concern with risk.1 While several hypotheses are
given below, there are undoubted!, others.
.
iSeveral reviewers and committee members comment that
they feel no compelling reason to explain "the apparent
contradiction between increased longevity and increased
OCR for page 4
4
Mortality Differentials
One source of concern about risk may be a growing reali-
zation that certain groups in society suffer from higher
than ordinary rates of early death. Despite historical
progress, it is increasingly apparent that there are
numerous opportunities for further longevity gains.
For example, two types of mortality differentials
suggest that it may still be possible to substantially
reduce mortality rates in the United States: the high
rates of mortality among disadvantaged groups in the
United States and the higher rates of mortality for the
entire U.S. population compared with that of many other
developed nations.
Blacks, Hispanic Americans, American Indians, and
the poor and poorly educated in general suffer from sub-
stantially higher death rates than do middle- and upper-
class whites. mese disparities should be understood in
the context of a period of dramatic improvement, at
least for some disadvantaged groups. Between 1950 and
1975, for example, both whites and nonwhites experienced
sharply reduced rates of infant mortality as well as
general increases for all ranges of age-specific mortal-
ity except for the very old. Although these improve-
ments were greater for nonwhites than for whites, mor-
tality differentials between the two groups remain
large. For example, if current mortality rates remain
unchanged, two of five nonwhites will die before reach-
ing age 6S, compared with one of five whites. Although
data are sparse, mortality and morbidity rates among
migrant workers in the United States appear to be espe-
cially high.
The United States fares poorly compared with other
developed countries in terms of a variety of health in-
dicators, including infant mortality, life expectancy,
cardiovascular disease rates, cancer death rates, and
homicide rates. For instance, the United States is 26th
on a list of countries in the probability of death be-
fore age 6S. In terms of reported mortality rates, the
concern about risker They go on to say that in their
opinion there i8 no real contradiction because of
reasons A, B. or C. Not all these critics, however,
agree on A, B. or C. "An apparent contradiction" is an
individual opinion: some believe it; others don't.
- , v ~
. .
OCR for page 5
United States ranks close to countries with less than
half the U.S. per-capita income.
The likelihood of death before age 65 for selected
countries is:
Rank Country Probability
1 Sweden .183
10 Canada .235
26 United States .275
37 Mexico .419
41 Liberia .665
U.S. whites, however, have a probability of death before
age 65 of .412.
Persistent differences in life expectancies, between
nations and between different groups in the United
States (e.g., whites and nonwhites), may mean that, for
the lagging populations, achievable mortality gains are
not being realized. These attainable gains also imply
inequities in the distribution of risk: some croups
carry higher burdens of risks. ~ r ~
tality differentials and the linked issue of equity in
the sharing of risks are surely part of the reason for
increased concern with risk despite general increases in
life expectancies.
Smoking and Drinking
The persistence of mor
Some mortality gains are attainable through individual
action. For example, alcohol consumption ranks second
to cigarette smoking as a behavioral cause of death.
The report by the U.S. surgeon general (1979) estimates
that "alcohol misuse is a factor in more than 10 percent
of all deaths in the tinited States" and cigarette smok-
ing is a factor in 17 percent of all deaths. Nonethe-
less, alcohol abuse produces social problems that, in at
least two respects, are more serious than those problems
caused by cigarette smoking. First, alcohol abusers
impose substantial costs on others (especially on family
and close friends) through homicide, suicide, spouse
beating, child abuse, and motor vehicle accidents.
. . . .
Second, alcohol abuse is a major cause of death at
younger ages. For instance, the surgeon general reports
that "alcohol-related accidents are the leading cause of
death in the 15 to 24 age group."
OCR for page 6
6
Cigarette smoking remains a major health problem,
despite reductions in the numbers of Americans who
smoke. As the surgeon general's report emphasizes:
Cigarette smoking is clearly the largest
single preventable cause of illness and pre-
mature death in the United States. . . .
Cigarette smokers have a 70 percent
greater rate of death from all causes than
nonsmokers, and tobacco is associated with an
estimated 320,000 premature deaths a year.
Another 10 million Americans currently suffer
from debilitating chronic diseases caused by
smoking.
In recent years, both the scientific and policy
aspects of the smoking problem have become more compli-
cated due to greater awareness of the interaction of
smoking with other contaminants, such as asbestos in the
workplace and community air pollutants.2
Increasing and Emerging Risks
The declining incidence of age-specific mortality fails
to reflect some especially pernicious risks that may be
increasing or emerging, including the risks of crime,
environmental contamination, and nuclear war. Since
many emerging risks could have been selected for discus-
sion by the committee, we have highlighted those that
polling data suggest are of most concern to Americans
(see Louis Harris and Associates, 1980~.
cat- - r-~
ZThat awareness. as one committee member comments,
does not always extend to an awareness of the relative
impacts of smoking alone versus smoking in combination
with other factors. Thus, if no one smoked tobacco, the
proximate cause of 320,000 deaths a year, including most
of the deaths of asbestos workers, would be eliminated.
If, however, asbestos exposure had never occurred, only
about 4,000 deaths would be eliminated, of which only a
few hundred could be additional to those eliminated by
stopping smoking.
OCR for page 7
7
Crime
For many Americans, especially those living in inner
cities, crime represents one of the most significant
risks of daily life. Since the early 1960s, violent
crime rates (murder, rape, robbery, and assault) have
increased sharply, and survey data reveal that crime Is
one of the risks of most concern e. O Americans. High and
rising rates of crime impose psychic costs on individ-
uals, which in turn impair the sociological health of
communities. Moreover, (except for murder) these in-
creasing crime rates are not directly reflected in
longevity statistics. For many Americans, the risk of
crime is especially serious and immediate.
Environmental Contamination
Although considerable progress has been made in the past
20 years in improving certain aspects of air and water
quality, serious environmental problems confront us, and
some environmental threats are increasing. Polling data
indicate that Americans continue to be concerned with
environmental degradation. That concern is seconded by
other indications of continuing and new problems. For
example:
.
.
o While national emissions and ambient levels of
sulfur dioxide and total particulates in the air
have declined since the 1960s, there may even be
increases in some geographical areas for sul-
fates and fine particulates, two pollutants that
may pose greater risks to human health than sul-
fur dioxide and total particulates;
U.S. emissions of sulfur and nitrogen oxides are
combining with water vapor in the atmosphere to
produce acid rain. As a result, the pH value of
precipitation in the United States and other
countries is frequently dropping well into the
acid range, posing threats to fish, wildlife,
and other organisms;
The production of chemicals increased by a
factor of 10 between 1945 and 1975, an indica-
tion of economic growth and prosperity; this
trend has also contributed to the growing prob-
lem of safe disposal of hazardous wastes;
i,
~e ~
OCR for page 8
8
· The burning of fossil fuels by the United States
and other countries is raising the amount of
carbon dioxide in the atmosphere, which is now
expected to significantly warm the global sur-
face and thereby to affect regional climate
patterns.
These and other persistent, growing, or emerging
environmental risks are not likely to be readily dis-
cernible in historical or current mortality figures, due
to long latency periods before adverse effects occur and
the difficulties of distinguishing environmentally
caused deaths from those caused by other factors. The
increased manufacture and use of toxic chemicals and the
rise in the incidence and the death rate from some can-
cers have been a source of controversy. Whether there
is a causal relationship between these two trends re-
mains an issue involving large scientific uncertainties
and considerable dispute among experts.3
Recent survey data indicate that "chemicals" are a
major source of increased perceived risk among the pub-
lic. m is finding underscores the importance of making
the level of this risk more precise and of explaining it
clearly.
Nuclear War
Although the vast nuclear stockpiles in the United
States and the Soviet Union may have deterred a major
military confrontation between these nations, such
weapons have also created a fear of quick and immense
destruction. The perceived risk of a nuclear calamity
varies and seems to correlate with the existing state of
tension between the superpowers. For example, after the
signing of the Limited Test Ban Treaty in 1963 and of
SALT I in 1972 the perceived risk was much lower than
during the period of high tension created by the Cuban
missile crisis. At this time, the uneasy relationship
between the United States and Soviet Union combines with
3A committee member observes that although most ex-
perts believe that there is no important causal rela-
tionship, the issue is so important that they tend to be
very cautious in their statements. The very '~edging"
raises concern.
OCR for page 9
9
the volatility of the Mideast to make the possibility of
a military confrontation escalating to a nuclear war a
substantial threat.4 Although it is not directly
measurable, the risk of nuclear devastation has probably
increased since 1972 as a consequence of increased
U.S./Soviet hostility and continued emphasis on nuclear
weapons development in both countries. The emergence of
China as a nuclear nation and the potential prolifera-
tion of nuclear weapons in the Third World have added
new dimensions to the threat of nuclear war.
The risk of nuclear war is identified in this report
for two reasons. First, it is crucial to identify those
major risks that are not reflected in mortality in-
dices. For example, the historical progress in increas-
ing life expectancy does not take into account the per-
sistent danger of nuclear war. Even if longevity is
increasing, the probability of death may be constant or
increasing if the probabilities of nuclear war are in-
creasing. Second, the polling data on public concern
about risks indicate the importance of global political
instability, a concern that may take on greater signifi-
cance due to nuclear armaments.
The risk of nuclear war is fundamentally different
from other daily risks of life for at least three rea-
sons. Nuclear war threatens not only individuals but
also current civilization and ecosystems. The risks of
nuclear war are largely beyond individual control and
may even be beyond one nation's control. Finally, rela-
tively little is known about the likelihood of a nuclear
confrontation's becoming an all-out exchange, the possi-
bility of limiting escalation, or the degree of devasta-
tion that would result from any nuclear war. These un-
certainties provide an opportunity for the likelihood or
consequences to be sensationalized or suppressed.
~e ~
Nuclear Power
Polling data indicate that the risks of nuclear power
are of considerably less concern to Americans than those
4A committee member comments that the increased mili-
tary aggressiveness of the United States may reduce the
probability of nuclear confrontation, because it signals
our determination to remain firm.
OCR for page 10
10
of nuclear war (Louis Harris and Associates, 1980~.5
Moreover, these concerns differ not only in magnitude
but also in kind. Rather than annihilation, the risks
perceived by most Americans are more local, as in a
meltdown catastrophe, or more subtle, as in genetic
damage to future generations resulting from long-tenm
exposure to ionizing radiation from nuclear plants or
from repositories for their radioactive wastes.
Also, large-scale nuclear power plants symbolize for
some the imposition of a relatively new technology,
which fosters an increasingly centralized and complex
society in which the power of the individual is dimin-
ished. Such concerns mean that debates on the course of
nuclear power are inevitably flavored not only by tech-
nical, economic, and political concerns but also, more
strongly than in other issues, by philosophical ones.
That debate continues to be vigorous in the United
States and abroad. At one extreme, advocates argue that
nuclear power provides an almost unlimited, low-cost
energy resource essential in the transition from non-
renewable fossil fuels to renewable forms, such as solar
power. At the other extreme, opponents see nuclear
energy as ushering in the potential for worldwide
calamity threatening human survival; they link nuclear
power with nuclear weapons and nuclear war, through the
proliferation of new nuclear powers and through national
and subnational terror; more important, they link the
acceptance of nuclear power with acceptance of nuclear
weapons and their use in another war. Those advocating
nuclear power argue that the knowledge of nuclear fis-
sion, even how to make bombs, is widespread. In this
sense the nuclear genie is out of the bottle. If a
country wants nuclear weapons, the proponents of nuclear
power argue, it can acquire the fissionable materials
needed via research reactors rather than power reac-
tors.
Also, despite the Three Mile Island accident, they
further argue that nuclear power has proven safer and
more environmentally benign than any other form of
energy, predicting that this record can be maintained
with continuing vigilance. Opponents challenge those
.
bA reviewer argues that perhaps 'the risks seen by the
public are of the same kind, not different, and that
this has been, in fact, one of the major stumbling
blocks to the public acceptance of nuclear power."
OCR for page 11
11
predictions, arguing that with wider use the chance for
accident and for radioactive contamination will inevi-
tably rise.
Lay people as well as scientists are split on those
issues. Even though public referenda have shown that
the bulk of public opinion lies well within the extreme
points of view given above, public apprehension about
nuclear power remains high. These uncomfortable strains
in the development of nuclear power undoubtedly contrib-
ute to apprehension in a significant sector of society
and hence to its belief that life is becoming riskier,
despite mortality statistics to the contrary.
_
RISK PERCEPTION
Anxiety about risk is a product of people's beliefs and
attitudes. People often form such beliefs and attitudes
on the basis of incomplete and often biased information
using fallible modes of inference, which sometimes
result in systematic distortions and misperceptions of
reality. These heuristics, although sometimes useful
and convenient, result in systematic distortions and
misperceptions of reality.
For example, scientific progress identifies new
risks, which are reported to the public. There are
reports on the risks of the Three Mile Island accident
hazardous chemical wastes in the Love Canal, DC-10s,
benzene, saccharin, asbestos, tampons, PCBs, the pill,
.
recombinant DNA, nuclear waste, and so forth. These
reports may make certain risks more memorable or imagin-
able, thereby increasing perceived probabilities of risk
regardless of the total scientific evidence about or
trends in actual indices of risk. If this phenomenon is
occurring on a large scale, it may explain part of the
rising public concern about risk.
As people become better informed about various
health and safety risks, levels of concern can be
expected to rise.6 This process is accelerated by
scientific advances that detect more and more previously
unknown sources of risk.
tA reviewer remarks that better information can
sometimes indicate decreased risks. While perceptions
of existing, real risks change, scientific advances may
introduce new risks and alleviate old ones.
OCR for page 36
36
reliability and acceptance of uncertainty. For
example, in a recent risk assessment--the one deal-
ing with ozone depletion--epidemiology, dose-
response extrapolation, chemical modeling and atmo-
spheric modeling, were employed in sequence in order
to estimate the potential increase in ultraviolet
light-induced skin cancer and malignant melanomas
possibly resulting from continued release of chloro-
fluorocarbons.
tne problems involved in compounding
the uncertainties by combining theoretical simula-
tion models, laboratory reactions, clinical observa-
tions, and epidemiological correlations have not
really been examined by the risk assessment litera-
. . and are an important research task.
Lure .
Value Trade-Offs and Ethical Considerations
in Risk Evaluation
Risk reduction is not society's only goal. Many of the
risks in society are worthwhile or acceptable, at least
in the sense that trying to reduce them would, all
things considered, make life worse. In some cases,
society may choose to increase certain risks in order to
attain other important goals. Certainly individuals do
so. Hang gliding is risky and could be considered un-
necessary, yet it is popular. There also may be compet-
ing risks. Lowering one may raise another, or lowering
one risk may be so costly to industry, and eventually to
consumers, that other, more effective actions cannot be
afforded. However, even if an action or a decision not
to take an action raises the net probabilities of ad-
verse consequences, it may have other, compelling bene-
fits. On balance, society may choose an option that
does not minimize long-term net risk.
The broad range of objectives that should be weighed
in deciding how to cope with a risk can be suggested by
a specific example: an analyst trying to evaluate the
consequences of some regulation intended to protect
human health or safety. The evaluator may want to
ponder various kinds of health effects, including how
many people would be affected, not only in the entire
population but also in sensitive groups. How much they
would be affected (in terms of mortality, morbidity,
pain, suffering, discomfort, and perhaps anxiety), who
they are (by age, income, occupation, geographical
location, etc.), and when they would be affected may
OCR for page 37
37
also be relevant. In addition, the evaluator may be
concerned about the degree to which the risk was volun-
tary or involuntary and about whether the effects would
be scattered across the country or concentrated in some
small group of people. But there are other measures to
consider. The evaluator should be interested in effects
on nature, economic growth, productivity, innovation,
business competition, the distribution of income, public
satisfaction with government, and the quality of busi-
ness and personal decision making. Pconomic costs--and
for whom--certainly matter, as might enforcement costs
and political costs. These and other considerations
such as aesthetics, due process, and international rami-
fications may all be highly uncertain, subject to reas-
sessment as new information is gathered, the target of
wide disagreement, and stretched out over time; the
evaluator might want information about this. Further-
more, an evaluator might want to know how identifiable
the victims are, the type of injuries to be expected,
the number of people affected, and how accountable the
decision maker will be as well as what the possibilities
are for delay, experimentation, flexibility, and adapta-
bility. There is more--this is just a partial checklist
that could be greatly expanded.
This list is not appropriate for all kinds of risks;
quite a different list would apply, for example, to arms
control. Furthermore, many decisions about risks will
not contain many of the items in the checklist above.
It is clear, however, that such lists will frequently be
long and that some very difficult trade-offs among com-
peting objectives will have to be made.
Much of the disagreement today about how to cope
with a variety of risks stems from uncertainty about
their magnitude: how hazardous is benzene or saccharin
or ionizing radiation? Extrapolations from observable
to nonobservable conditions, either in dose level or
from animals to humans, will probably remain conten-
tious. If, however, contrary to all expectations all
such scientific imprecision could be resolved, contro-
versy would still abound and perhaps would be even more
vehement. Instead of a heated argument about linear
versus nonlinear extrapolations from high to low dose
rates, the dispute might be about the role of government
in a free society.
A few simplified examples of some of the most per-
plexing problems involving ethics and value trade-offs
are sketched below.
OCR for page 38
38
Bow much of society's limited resources should be
allocated to life-saving activities versus other pres-
sing social concerns?
If you had to make the uncomfortable choice of
saving an anonymous 1-year-old's life or that of an
anonymous 20-year-old or 60-year old, which would you
choose?
How important is the psychological well-being asso-
ciated with clean air and blue skies compared with vari-
ous levels of economic well-being?
How should on an asthma attack suffered by a 30-
year-old be compared with a bout of emphysema suffered
by a 60-year-o1d?
How should our society decide whether to save the
lives of inhabitants of North America 100 years from now
versus saving starving Sahelians now?
Do we have the responsibility of maintaining ecolog-
ical balances for nature's sake rather than--or in addi-
tion to--for people's sake?
To what extent should society be willing to impose
. . . · ~ ~ _
costs and risks on a few members of society in order to
benefit most members of society?l5
When should heroic measures be taken to prolong life?
When should governments restrict individuals from
self-hazardous behaviors?
These long-standing issues of value are common in
risk and decision making. While science and profes-
sional analysis may contribute to a more informed debate
concerning these trade-offs, they cannot resolve them;
they may, however, help to define and structure those
value trade-offs. This perspective is important
because it highlights the limited albeit important role
of science and professional analysis in resolving
disputes over decisions about acceptable risk.
5A variation of this is: To what extent should
society be willing to impose small costs and risks to a
large number of members of society in order to greatly
benefit a few members of society? There would be a
large societal consensus on the answer if the above
question were changed to say, imposing great costs to
many that modestly benefit a few.
OCR for page 39
39
THE ROLE OF SCIENTISTS AND SCIENTIFIC INSTITUTIONS
Many scientists are active in public debates about risk
and decision making. As citizens they should be in-
volved in the political process. Indeed, it can be
argued that scientists who can understand the technical
intricacies of complex problems have a special obliga-
tion to speak out on controversial issues. But there is
a price society pays for this openness. Passionate
claims by equally eminent scientists on diametrically
opposed sides of a policy debate may bewilder lay
people. me media may exacerbate this problem by
focusing attention on extreme opinions that are accom-
panied by ringing rhetoric. It is hard, for the media
and for the general public, to sort scientific judgments
from what is primarily value-based or political opin-
ion. In some cases scientists cloak controversial value
judgments in scientific jargon, both consciously and
unconsciously. As a result, the prestige of science and
public confidence in science suffers. This dilemma has
profound implications for science. It may affect--some
say that it already has affected--funding for science,
the selection of professions by college students, and
the willingness of scientists to participate in the
policy process. Furthermore, scientific progress may
hold one of the keys to better and healthier lives for
all, especially those in the disadvantaged, developing
world; ironically, scientists, although meaning well, by
engaging in heated debates involving unscientific value
· ~ . . . · _ -
Judgments may be undermining the tuture potential ot
science for amelioration of the world's ills or for
coping with the critical problems created by overpopula-
tion, the depletion of resources, and the degradation of
the environment. (Some committee members feel that the
above remarks understate the gravity of the problem;
others find them a bit melodramatic but worthy of re-
flection.)
Scientists engaged in debates about risk and deci-
sion making should, whenever possible, attempt to say
where their scientific expertise ends and where their
personal value judgments begin. Of course, a scientist
may not know where the boundary between the two falls;
scientific expertise and value judgments may fuse, but
an attempt should be made to disentangle the two. Of
course, there may be a continuum of states of fuzziness,
but an attempt should be made to communicate this fuzzi-
ness. Further, scientists in public debate should,
. -- .... ~ I.
-
OCR for page 40
40
whenever possible, refer to credible evidence not sup-
porting their views.
Committees of specialists working under the aegis of
prestigious scientific institutions who have been asked
to perform some risk analysis have a responsibility both
to the committee's client, the public, and the commit-
tee's parent institution. These responsibilities are
jeopardized when tasks are accepted that are inappropri-
ate for the committee and its parent institution. For
example, a committee of physical scientists sponsored by
an engineering institute may not be the appropriate com-
mittee to recommend policies for balancing concerns
about health and safety risks with value trade-offs and
political constraints. Some scientists on the committee
may be knowledgeable about policy concerns, but if their
expertise is sought and their institution's imprimatur
is given on the basis of their professional expertise as
physical scientists and not as policy analysts, then it
may be inappropriate for them to make pronouncements
that extend beyond their disciplinary expertise. Cer-
tainly if they feel compelled to offer policy recommen-
dations, such excursions should be clearly labeled in
their report. Outside the committee, the members have
the right and the duty to speak out on the issues, but
the committee is not serving its parent institution, the
. . . . . .
Drosoer scenic community, or the public if it ex-
pands its consultative role from the descriptive assess-
ments of scientific phenomena to the prescriptive evalu-
ations of policy choices--if that was not their assigned
task.16
Committees are often specifically asked by their
clients to suggest recommendations for policy choice
"all things considered." Depending on the composition
of the committee this may not be unreasonable, but com-
mittees should be careful lest they become used and
manipulated in a political process. Sometimes a good
decision may result from shifting the burden of choice
from a highly politically charged regulatory commission
to some quasi-scientific body of experts, but the shift
16A commentator remarks: The scientific community
needs to figure out ways to defend scientists who par-
ticipate in these debates and then find themselves
having their good faith questioned. This constitutes a
significant disincentive for reputable scientists to
become involved.
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may be made at the expense of confusing the role of the
parent scientific institution. Scientific institutions
should and sometimes do inform a potential client that
its interests (and society's broad interests) would be
better served if the scope of the assignment is limited
to nonprescriptive, nonevaluative scientific assessments.
To talk about assessment and evaluation--their sepa-
ration and integration--in risk analysis, we purposely
draw sharp lines around each. ~ ~ ~^ ~
These lines are difficult
to draw and members of many committees do not think
deeply about these distinctions. Even if the agreed-on
scope of a committee is to concentrate its attention on
descriptive science, the committee may nevertheless
slide into prescriptive, evaluative elements of an
analysis, not as a conscious decision but as a natural
consequence. Our suggestions are not stark. We are not
saying, 'tDo not mix evaluation with assessment"; rather
we are saying, "Be conscious of what you are doing. If
evaluative components are prominent in your report, was
such an emphasis intended? Has the committee been
appropriately chosen for this task? Did the committee
spend enough time considering the dynamics of choice,
value trade-offs, and political and legal constraints
before they arrived at their policy conclusions?t' These
questions suggest there may be a conflict of interest
between the needs of a client and the reputation of
scientific institutions.
A troublesome and not uncommon conflict is the
degree to which political feasibility should be con-
sidered in risk assessments. A committee may opt to
consider an issue purely on technical and economic
grounds only to have its judgments labeled as polit-
ically naive; or it may indeed consider the political
climate in weighing different options and be accused by
its sponsor of overstepping its charge. A reasonable
path between these two traps is for the assessors to
clearly distinguish between judgments based on technical
and economic grounds and those based on political con-
siderations. That, again, is a matter of competent
integration of assessment with evaluation.
SOME ISSUES IN RISK ASSESSMENT
There is one major source of controversy that plagues
many risk assessments: How far should speculative
numbers be pushed and combined? If benefits are
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quantified, then there is the criticism that the 'Ward
drives out the soft," that aesthetic, fragile values are
ignored. Yet if these soft values are subjectively and
numerically assessed, the resulting numbers are then
subject to attack. If there is a vitrolic debate about
whether some intangible benefit should be evaluated as
worth $10,000 or $20,000, it may be easier to do the
allegedly objective thing and leave it out altogether
--i.e., to make it "zero." Critics complain about the
failure of formal techniques to incorporate the intan-
gible hunches and intuitions of experts; but if these
hunches are incorporated by numerical scaling techniques
(e.g., by subjective probabilities), then they can be
easily ridiculed by skeptics.
In the debate about how far to quantify, as in most
long-standing debates, there are errors of two kinds in
the balancing equation: A false sense of precision with
numbers may give the impression that more is known than
is really known; and a false sense of imprecision with-
out numbers may give the impression that less is known
than is really known.
Risk assessments deal with uncertainties: some are
based on copious amounts of relatively uncontroversial
statistics (such as assessments of motor vehicle risks);
others are based largely on reasoned speculation (such
as assessments of the possibilities of sabotage of a
nuclear power plant). In the former type of cases,
nearly everyone would agree about the relevance of sta-
tistics and estimates of probability. In the latter
type of cases, although most people might have a hard
time seeing how numbers can be used at all, a few people
might want to numerically scale the judgments of ex-
perts. hey would argue: We cannot ignore the problem
of making assessments because decisions must be made,
even if the decision is "no change." The problem is how
to be appropriately precise about the state of impreci-
sion. Some might paraphrase this as how to be appropri-
ately imprecise about utter chaos. It is important for
decision makers to know not only what is known but also
what is not known.l7
70ne member of the committee points out that this is
the procedure now recommended for dam failures, for
which there is little theory and limited experience but
a great deal of expert judgment.
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There are numerous arguments for and against the use
of numerical probabilities in risk assessments. But
lurking in the background is a question: If you do not
use probabilities, then what do you do and how will it
respond to policy needs? Should experts, for example,
report their subjective judgments about uncertainties
when such judgments cannot be formally based on objec-
tive data or on well-articulated theoretical models?
All agree that if subjective judgments are reported,
they should be clearly labeled as such and accompanied,
insofar as possible, by supporting arguments. However,
some would shun subjective statements in scientific
documents altogether, especially the mixing of subjec-
tive and objective judgments. It should be noted that
our reference is not to subjectivity in value and poli-
tical judgments, but to expert judgments about uncer-
tainties, such as the uncertain severity of a toxic
substance. In risk assessment, these philosophical
debates about the very foundations of statistical
inference have some profound, practical implications.
In many investigations of the uncertainties of
risks, the scientific facts speak for themselves without
the need for expert synthesis; just marshalling and
exhibiting them is sufficient advice to the policy
maker. In other cases, however, the facts pull in
different directions with different degrees of credi-
bility, and if all this raw information were accurately
and completely reported, it would overwhelm any policy
maker. Policy makers may want experts to interpret and
synthesize those facts, so that they can incorporate
values and political concerns to arrive at a balanced
decision. But synthesis cannot simply be computerized.
It remains an art form, and judgments--expert judg-
ments--have to be factored in. Yet ideally the policy
maker wants the specialists to stick to their craft; the
policy maker wants to learn what the specialists know
about the scientific uncertainty and not about their
value preferences or their political perceptions.
The object is to communicate information from
assessors to evaluators in a manner that will be useful
in making policies and decisions. The synthesis of
assessment information is profoundly influenced by
whether these reports are cast in a subjectivist or an
objectivist mode. Subjectivist reports may be more
responsive to the evaluators' needs but may have a more
difficult time in peer review.
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Specialists disagree for many reasons, and some of
them persist in disagreeing after they listen to each
other at length. Perhaps there are communication bar-
riers, or perhaps they talk in different paradigmatic
languages, or perhaps they cannot articulate how they
really feel, or perhaps they are distrustful of each
other and are acting strategically.
But disagree they
often do. The question in what to do about such
disagreements. A good case in point is a recent NRC
report on the effects of radiation (National Research
Council, 1981~. In extrapolating carcinogenic effects
from high doses to low doses of radiation, the experts
are divided on the appropriateness of three underlying
extrapolatory models. In this case the experts can
agree about what they disagree about--at least at the
level of the choice of a model. The answer is not
critical for all policy decisions--all models, for
example, lead in some cases to the same policy con-
clusion. But if not, what then? Can they agree on why
they disagree about the appropriateness of the three
models? Given that they disagree about fundamentals,
can they agree on a compromise assessment report to give
to the policy maker? How should groups report their
~ r - - -r
disagreements? A proper separation and integration of
assessment and evaluation can founder at this juncture.
Indeed, it may be so difficult for an assessment group
to agree on a synthesis that it may be necessary to fuse
assessment and evaluation.
Government agencies frequently ask scientific organ-
izations to perform rink analyses by using the committee
arrangement. If the task of the committee lies exclu-
sively with risk assessment, then the membership of the
committee should be structured primarily to yield a
balanced portfolio of relevant scientific and methodo-
logical skills rather than a balanced portfolio of
policy viewpoints. This procedure would encourage open,
honest, and nonadversarial interactions and discourage
strategic, posturing regarding policy values.
Some caveats apply to this, however. For one, the
committee's membership and its capacity for calling on
different sorts of experts should remain flexible as its
perceived needs evolve during the study with deepening
insights. In addition, as we emphasized earlier in com-
menting on the difficulties of integrating assessment
with evaluative components, there is a need for active,
iterative interchange between the assessment committee
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and those who will use its report in formulating poli-
cies and decisions. Otherwise the committee may solve
the wrong problem, grapple with issues irrelevant to the
evaluator, or fail to gather the most important infonma-
tion. Finally, it is not always easy in selecting com-
mittee members to separate scientific competence from
policy involvement; indeed, that competence may be due
In part to Involvement In policy. Rigidity in selecting
members purely for scientific competence may result then
in a committee tilted toward one side of a policy de-
bate. In that situation, corrective compromises may
have to be made or the tasks of the committee modified.
If these compromises are not made, then the public
might, incorrectly, perceive ~ ~~
biased.
the committee s report as
Assessment reports commissioned by clients for the
policy process are generally made public and reviewed by
the scientific community. Peer reviews, whether for-
mally commissioned or individually motivated, serve many
functions: They may help potential users judge the
calibre and integrity of the report; they partially
motivate the authors of the report to be more respon-
sible; they help to weed out errors; they may stimulate
others to accumulate new evidence that would be relevant
to any reassessment; and they focus attention on the
weak links of the analysis.
The peer review process is most effective when there
is a clear demarcation of analytical tasks. When risk
assessment and risk evaluation activities are mixed, it
is especially difficult to orchestrate an organized
review by appropriate specialists. Yet when risk as-
sessment is conducted separately from evaluation, an
elaborate and flexible review process can improve the
quality of assessments and evaluations. For example,
not only can there be reviews of the primary assessment
report, but also, in a somewhat adversarial style, there
can be reviews of the reviews. Funding agencies for
risk assessments can incorporate a dynamic review pro-
cess into funding decisions. It might be advisable to
reserve substantial monies for peer review or possibly
to fund two independent risk assessments, depending on
the importance of the problem at hand.
A final note. It is very hard to separate assess-
ment from evaluation. And it is hard to do good risk
assessments; there are not many examples of such assess-
ments that blend well into the evaluation tasks. How-
ever, the technique of deliberate separation is fairly
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new. When done well, the results often repay the diffi-
culties. Egregious errors are filtered out; high-
quality reviews are more 1 ikely; and the overall stan-
dards o f risk analyses are raised .
Representative terms from entire chapter:
social intervention
