Date: Wed, 30 Jun 1999 19:35:02 -0400 (EDT)
Subject: Rachel #657: The Uses of Scientific Uncertainty
From: [log in to unmask]
. RACHEL'S ENVIRONMENT & HEALTH WEEKLY #657 .
. ---July 1, 1999--- .
. HEADLINES: .
. THE USES OF SCIENTIFIC UNCERTAINTY .
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THE USES OF SCIENTIFIC UNCERTAINTY
A revolution is occurring in the way science is used in
environmental regulation. Like most revolutions, this one is
causing some pain and some disruption, and of course it is being
opposed viciously by those who profit from the present system.
But the revolution is occurring nevertheless, and the ultimate
outcome seems assured. When the revolution is complete, it will
be a great day for public health and for the environment.
Scientists often define "scientific certainty" as "being 95% sure
that cause and effect have been correctly identified." It is
exceedingly rare for a large group of scientists to be 95%
certain about anything, especially about anything as complex as
an environmental problem. When you're talking about living
systems, great scientific uncertainty is the norm. Even in the
case of an ultra-well-studied chemical like dioxin, scientific
uncertainty far outweighs firm knowledge of cause and effect.
How is scientific uncertainty currently treated in environmental
protection? For 50 years it has been used permissively. It has
been used to postpone actions that would protect public health.
The classic case is the introduction of tetraethyl lead into
gasoline. (See REHW #539, #540.) When chemical and automobile
corporations announced they were starting to put highly-toxic
tetraethyl lead into gasoline in 1922, numerous public health
officials thought it was a dangerous idea and they urged delay
and careful study. But the corporations argued that there was no
scientific agreement about the threat; in the absence of
convincing evidence of widespread harm (which had not yet
occurred, so couldn't be documented), they insisted they had the
right to proceed. Basically, they argued, "Until you can line up
the dead bodies, we can do whatever we want." On that basis, the
corporations pressed ahead heedlessly with the new toxic
technology, thus setting the standard for corporate behavior over
the next 50 years. The consequences of that particular decision
are now a matter of record -- tens of millions of Americans
suffered brain damage, their IQs permanently diminished by
exposure to lead dust.
Because we have allowed scientific uncertainty to postpone
controls on dangerous activities, we now have hazardous levels of
mercury in most of the nation's fresh-water fish; the Earth's
ozone shield has been dangerously depleted; global warming is
upon us, with attendant droughts, fires, floods, hurricanes,
tornadoes and typhoons; the ocean's major fisheries are in
serious decline; the normal sex ratio of male-to-female babies
has been changed in numerous industrialized countries, and human
sperm counts have declined 50% in 50 years; immune system
disorders like asthma and diabetes are steeply rising; many of
the world's coral reefs are dying; cancers of the brain, the
lymph system, the blood system and the testicles are increasing;
cancer in children is escalating; many species have gone
extinct.... This list of contemporary calamities could be readily
But now people are waking up. They are waking up to the fact that
scientific uncertainty should be cause for caution, not for
plunging ahead recklessly. When flying blind, if you are not sure
whether that shape looming just ahead is a cloud or a mountain,
slow down. A stitch in time saves nine. If you aren't sure what
you're doing, you should proceed slowly and carefully, or perhaps
not at all. Better safe than sorry. That is the philosophy of
In truth, the principle of precautionary action has seemed a bit
abstract, until now. It has seemed like a fine philosophy, but
how would it work in actual practice? Now a new handbook from the
Science and Environmental Health Network (SEHN) fleshes out this
important philosophy of environmental protection, describing how
it can work at the local level.
The United States is already under obligation to operate by the
precautionary principle. The federal government signed and
ratified the Rio Declaration from the 1992 United Nations
Conference on Environment and Development. The Rio Declaration
says, "In order to protect the environment, the precautionary
approach shall be widely applied by States [meaning
nations--P.M.] according to their capabilities. Where there are
threats of serious or irreversible damage, lack of full
scientific certainty shall not be used as a reason for postponing
cost-effective measures to prevent environmental degradation."
Therefore, it is not a matter of WHETHER the U.S. will abide by
the precautionary principle, but HOW.
The precautionary principle is now embedded in numerous
international treaties and conventions: the Second North Sea
Declaration; the Bergen Declaration on Sustainable Development;
the Ministerial Declaration of the Second World Climate
Conference; the Maastricht Treaty on the European Union; the
Helsinki Convention on the Protection and Use of Transboundary
Watercourses and International Lakes; and others.
Thus the stage is set. All that remains is for organizers and
activists to press the precautionary principle into service at
the local and state levels. The new guidebook from SEHN shows
The precautionary principle says that decision-makers have a
general duty to take preventive action to avoid harm before
scientific certainty has been established.
The test for knowing when to apply the precautionary principle is
the combination of threat of harm and scientific uncertainty.
Some people would say that the threatened harm must be serious or
irreversible, but others point out that this does not allow for
the cumulative effects of relatively small insults.
Instead of asking how much damage or harm we will tolerate (which
is the approach taken by risk assessment), the precautionary
principle asks how to reduce or eliminate hazards, and it
considers all possible means for achieving that goal, including
scrapping the proposed activity. (Of course, alternatives to a
hazardous activity must be scrutinized as carefully as the
hazardous activity itself.)
The precautionary principle shifts the burden of proof.
Proponents of an activity should prove that their activity will
not cause undue harm to human health or the ecosystem. Those who
have the power and resources to act to prevent harm have a
responsibility to do so. That responsibility has 2 parts:
financial liability for anything that goes wrong. [A performance
bond posted up front (common in the construction industry) is the
best way to handle this. See REHW #510.] The second part of
responsibility is a duty to monitor, understand, investigate,
inform and act. Ignorance and uncertainty are no longer excuses
for postponing actions to prevent harm.
The steps in taking precautionary action are not complicated:
1. Describe and understand the problem or threat. How big is it?
How far could it extend in space and time? Are there indirect
impacts (for example, after the product is thrown away)? How
serious could the effects be? Similar questions are raised
whenever an environmental impact statement is written in response
to the National Environmental Policy Act (NEPA), so there is not
much new here.
2. Describe what is known and what is not known. There are many
kinds of uncertainty (which the SEHN HANDBOOK does an excellent
job of describing). Are we dealing with something that is
unknowable, or about which we are totally ignorant? (If so, this
is a good reason not to proceed.) What would it take to reduce
the uncertainties? (Some uncertainties can be reduced and some
cannot.) The SEHN HANDBOOK provides a good guide for
understanding uncertainties: "Environmental and public health
advocates have to ask difficult questions of industry and
regulators to expose the depths of our ignorance. Once this lack
of knowledge has been exposed, the notion of needlessly exposing
humans and the environment to hazards without information on
their effects seems irrational, and precaution seems logical."
3. Identify alternatives to the activity or product. First
restate the problem to describe the purpose of the activity. A
development provides housing; a solvent provides degreasing; a
pesticide provides pest management. Now examine all of the
alternative ways of fulfilling the purpose, to find the one that
minimizes damage to people and to the environment.
4. Determine a course of action. How much precaution seems called
for? Stop the proposed activity? Demand alternatives? Demand
modifications to reduce bad impacts? Demand that a performance
bond be posted up front?
5. Monitor. Those undertaking the activity should bear the cost
of monitoring, but it should be conducted by an independent party
(when possible). The monitoring information might warrant
additional actions, or different actions.
The HANDBOOK then compares precaution to the way decisions are
made now -- by risk assessment. Risk assessment does not fare
well in the comparison.
The HANDBOOK ends with a section called "Answering the critics."
Critics of the precautionary approach say things like, "It is not
based on sound science" and, "This is emotional and irrational"
and, "This will halt development and send us back to the stone
age," and, "We comply with regulations so we are already
practicing precaution." The HANDBOOK patiently provides reasoned
responses to each of these dumb statements and several others as
The precautionary principle has American industry scared to
death. Precautionary action immediately makes sense to people.
Everyone can understand the wisdom of, "Do unto others as you
would have others do unto you" and, "Better safe than sorry." The
precautionary principle combines scientific validity with ethical
force. No wonder corporations (and their handmaidens in
government) consider it a threat to business as usual. It IS a
threat to business as usual.
Industry's best hope is to adopt the language of precaution with
great fanfare, while pressing ahead with the same old risk-based
projects and programs, hoping no one will notice. To this end,
the Harvard Center for Risk Analysis, a chemical industry think
tank, held a conference last month to develop strategies for
countering the precautionary principle. Participants openly
scoffed at precaution. One participant described how his mother
used to make him wear a sweater whenever he went outside, even
though he lived in southern California. That pathetic little
anecdote drew a loud, nervous laugh from the assembled throng, as
if it had scored big points against the wisdom of precaution.
Participants had paid good money to attend the Harvard seminar,
hoping to learn how to shore up the sagging fortunes of risk
assessment. But even Big Heads from Harvard cannot salvage a bad
idea whose time has gone. All risk assessments are fiction, shot
through with assumptions, guesstimates, judgments, and biases --
all disguised disingenuously as "good science." The only thing
that allows risk assessors to hold their heads up in public is
that most people don't have the faintest idea what risk assessors
do for a living or the consequences their work entails.
The principle of precautionary action, on the other hand,
embodies all aspects of science -- including uncertainty -- in an
ethical procedure aimed at ELIMINATING risks (something no risk
assessment has ever aimed to do).
In the long run, the ethical way will prevail.
(National Writers Union, UAW Local 1981/AFL-CIO)
 Joel Tickner, Carolyn Raffensperger, and Nancy Myers, THE
PRECAUTIONARY PRINCIPLE IN ACTION-- A HANDBOOK (Windsor, North
Dakota: Science and Environmental Health Network, 1999). E-mail:
[log in to unmask]; mail: SEHN, Rt. 1, Box 73,
Windsor, ND 58424; telephone and fax: (701) 763-6286.
Descriptor terms: precaution; precautionary principle; risk
assessment; carolyn raffensperger; joel tickner; science in
decision-making; decision-making; regulation;
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