The precautionary principle
is a new way of making decisions about environment and
health. The purpose of the precautionary approach is to
make decisions today that we will not regret in 50 years.
As the precautionary approach becomes better known, it
is being studied and criticized, which is normal for new
ideas. Here we present common criticisms of the precautionary
approach, and then offer some responses to the critics.
Naturally, ours are not the only possible responses.
Before proceeding, we should distinguish
the precautionary approach From the old way of making
decisions. (I call it the "old way" because
is being replaced by the newer precautionary approach
in many parts of the world-but in most parts of the U.S.
the "old way" is still being used.)
The old way of making decisions assumed
that we could do a "risk assessment" on any
activity (such as adding the chemical MTBE to gasoline,
or burying radioactive waste in the ground, or cutting
new logging roads into a forest). The risk assessment
would tell us the likelihood and amount of harm from the
activity, and we would then enforce limits on the activity
to prevent the harm from growing beyond "acceptable"
levels. In the case of harms that are rare or unknown,
the old way assumes that we will learn about these hidden
dangers in ways that may be unpleasant and traumatic but
which will not be unacceptably costly or painful.
The old way assumed that people and corporations
have the right to do anything they choose (so long as
it is legal) until some third party can prove that harm
has occurred, at which point a lengthy process of dispute
resolution can begin, often requiring decades of effort
and millions of dollars. This system requires that harm
must occur and must be proven to occur before alternative
actions will be considered. The great harms from leaded
paint, from leaded gasoline and from asbestos come to
In sum, the old way asked the question,
"How much harm is acceptable" or "How much
harm can we get away with?" and then tried to limit
activities to keep the harm within those boundaries. And
the burden of proof of harm was placed on those being
harmed-it was up to them to prove they were being harmed
before alternative actions would be considered.
The precautionary principle is a different
way of making decisions-one focused more on preventing
In one form or another, the precautionary
principle has been widely adopted in international treaties
and agreements, and it has even been formally adopted
by the U.S. government, which signed the Rio
Declaration on Environment and Development in 1992.
(Unfortunately, the U.S. has not yet acted on that commitment.)
Criticism #1: There are many ways of stating
the precautionary principle, so it is meaningless.
In all formulations of the precautionary
principle, we find three common elements:
1) If we have reasonable suspicion of harm
2) accompanied by scientific uncertainty, then
3) we all have a duty to take action to prevent harm.
The precautionary principle does not tell
us what kinds of action to take. It does not tell us to
ban anything or stop anything or regulate anything. However,
it assumes that our aim is to prevent harm, and a consensus
is developing that several kinds of action may be helpful:
** set goals;
** examine all reasonable alternatives for
achieving those goals with the expectation that the least-harmful
approach will be preferred;
** shift the burden of proof to the proponents
of new activities or technologies-they bear the burden
of producing information about the expected consequences
of their proposed activities, monitoring and reporting
as the activity unfolds, agreeing to pay for any harm
that ensues, and taking responsibility for remediation
as needed; and
** those who will be affected by the decision
should help make the decision.
Therefore the precautionary principle is
sufficiently well-defined for people to use it in the
Criticism #2: Precaution is not needed.
The current regulatory system is working well and there
is no need to change it.
Response #2. There are many well-documented
cases in which the "old way" has handed us a
legacy of very expensive problems that we are now paying
for (and struggling to solve), including: depleted fisheries;
harm from radioactivity; exposures to benzene, asbestos,
and PCBs [polychlorinated biphenyls]; damage to the Earth's
ozone shield; exposure to the artificial hormone, diethylstilbestrol
(DES); the excessive use of antimicrobials and growth
promoters; lead in gasoline, and MTBE as a substitute
for lead in gasoline; tributyl tin as an anti-fouling
paint on ships and boats; chemical contamination of the
Great Lakes; and more. This list could be readily extended-contamination
and depletion of salmon, low levels of many exotic chemicals
in typical drinking water supplies; loss of species at
100 to 1000 times historical rates of extinction; water
shortages in many parts of the globe including the American
west; increasing occurrences of asthma, diabetes, nervous
system disorders, childhood cancers, and so on.
Criticism #3: The precautionary approach
aims to achieve zero risk, which is impossible.
Response #3: Advocates of the precautionary
principle understand that modern technologies will always
entail risks, and that zero risk is not achievable. The
goal of precaution is less risk, not zero risk.
However, the precautionary approach responds
in a new way to risks. As we saw above, the "old
way" asks "How much harm is acceptable?"
The precautionary approach asks, "How much harm is
avoidable?" The precautionary principle is needed
when something that we value greatly is threatened and
requires preventive and protective action, to avoid threats
to it, or to prevent threats from materializing into harm.
The precautionary principle is especially
needed to avoid harms that could become widespread, serious,
or irreversible. Precaution also favors avoiding any harms
that are easily avoidable. In sum, "Better safe than
sorry" and "A stitch in time saves nine."
Criticism #4: The precautionary principle
Response #4: The precautionary principle
embraces and uses all available science. There is nothing
anti-science about it.
A key distinction between the "old
way" and precaution is their different responses
to scientific uncertainty. The old way takes scientific
uncertainty as a green light-until science can prove harm,
The precautionary principle takes scientific
uncertainty as a yellow light or even in some cases a
red light. The precautionary principle assumes that scientific
uncertainty is itself a reason to be concerned. When scientific
uncertainty is combined with reasonable suspicion of harm,
then precautionary action is warranted.
When we see smoke billowing out of a building,
do we passively study the situation until we are 100%
sure of the cause of the smoke, or do we call the fire
department (preventive action) while we simultaneously
try to learn more?
Some critics seem to feel that the precautionary
approach is anti-science simply because it pays attention
to scientific uncertainty. But science always makes a
careful distinction between what is known and what is
not known-so paying attention to uncertainty is a normal
part of science. As citizens, paying attention to uncertainty
is only common sense -- if we're not sure what we're doing,
we should proceed cautiously.
Criticism #5: The precautionary principle
will stop progress. If we had used precaution as our guide
in 1890, we'd never have developed the automobile.
Response #5: In 1890, people needed better
means of transportation to replace the horse. If a precautionary
approach had been taken in 1890-1900, the alternatives
available at that time would have been considered (trains,
omnibuses, electric trolleys, cable cars, plus electric
automobiles, steam-powered automobiles, and automobiles
using the gasoline-powered internal-combustion engine).
Unfortunately, a small number of people dominated the
decisions in 1900 and they chose to develop the gasoline-powered
internal combustion engine, and later to buy up and dismantle
competing trolley and train lines. Today, we are all struggling
with the consequences of those decisions (global warming,
cities clogged with highways and cars, the deaths of 60,000
people per year from air pollution and another 40,000
killed in accidents, and so on). People needed new forms
of transportation in 1900 but the decisions made at that
time did not follow a precautionary approach, and they
turned out badly. A precautionary approach would at least
have forced an open consideration of the risks and benefits
of each alternative, and would have given preference to
the least harmful. Such a process would not have left
us all riding horses, but it might very well have produced
a different transportation system than the one we are
struggling to replace today because it has proven to be
so expensive and so harmful.
Criticism #6: Precaution will stifle innovation
and destroy jobs. (This is similar to Criticism #5.)
Response #6: On the contrary, the precautionary
principle is already stimulating technical innovation,
as we search for new ways to fulfill our needs while minimizing
harm to the environment and human health. Much modern
technology is incompatible with living things, and it
needs to be replaced by newer technologies based on principles
learned from nature. Precaution creates incentives for
"green chemistry," "green engineering,"
and "green design." We need transportation-but
the best answer probably isn't gas-guzzling cars. We need
energy-but probably the best answer isn't burning more
coal or creating more unmanageable radioactive wastes
in nuclear power plants. We need food-but farms heavily
dependent on synthetic fertilizers, chemical pesticides,
and genetically engineered crops may not be the best answer
because they are so costly.
Human needs have not changed, and they will
be fulfilled one way or another. The question is, will
we harm the planet and diminish our children's future
as we fulfill our needs, or can we find ways to live in
harmony with nature? In developing advanced technologies
that are compatible with nature, entrepreneurs will find
(and create) wonderful opportunities for themselves and
others. Transportation, manufacturing, agriculture and
energy systems all need to be re-invented, based on cooperating
with nature rather than subduing it. The opportunities
job creation are obviously substantial. [To be continued.]
 The language of precaution has now
been adopted in many international treaties and conventions,
such as the North Sea Declaration (1987), The Ozone Layer
Protocol (1987), the Ministerial Declaration of the 2nd
World Climate Conference (1990), the Maastricht Treaty
that created the European Union (1994), The United Nations
Law of the Sea (2001), and the Cartagena Protocol on Biosafety
(2000), among others.
 Rio Declaration on Environment and Development
(1992); Principle 15 of the Declaration says, "In
order to protect the environment, the precautionary approach
shall be widely applied by States [nations] 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." Cost-effective
means lowest-cost. Available at http://www.rachel.org/library/getfile.cfm?ID=377
 Carolyn Raffensperger and Joel Tickner,
eds. Protecting Public Health and the Environment; Implementing
the Precautionary Principle. Washington, D.C.: Island
 Poul Harremoes and others, Late lessons
from early warnings: the precautionary principle 1896-2000
[Environmental Issue Report No. 22] (Copenhagen, Denmark:
European Environment Agency, 2001). Available at
(3-megabyte file): http://www.rachel.org/library/getfile.cfm?ID=301
 Carl Cranor, "Some Legal Implications
of the Precautionary principle: improving information-generation
and legal protections," European Journal of Oncology
(2003; Supplement 2), pgs. 31-51. http://www.rachel.org/library/getfile.cfm?ID=373
 Frank Ackerman and Rachel Massey, Prospering
with Precaution; Employment, Economics, and the Precautionary
Principle (Medford, Mass.: Global Development and Environment
Institute, Tufts University, 2002).
Available at http://www.rachel.org/library/getfile.cfm?ID=218
Last issue we began answering some of the
criticisms of the precautionary principle. Of course,
ours are not the only possible answers.
The precautionary principle is a new way
of making decisions, and it is slowly replacing the "old
way." Here is an example of how the "old way"
worked: someone develops a new chemical for cleaning refrigerators.
They do a "risk assessment" on that chemical
and determine that it will only cause "acceptable"
harm to humans and the environment. They commercialize
the chemical, create a "need" for it by advertising,
and rake in the money. They have strong incentives not
to study the effects of their chemical, so the first signs
of trouble are reported by citizens, and those early reports
are ridiculed, denied and labeled "junk science."
After a couple of decades, the chemical manufacturer (without
ever admitting that the citizens were right) introduces
refrigerator-cleaning chemical that they say is a big
improvement and will only cause "acceptable"
harm. Their risk assessment proves it. The merry-go-round
The precautionary principle begins by asking,
"What's the goal?"
Clean refrigerators. "What's the least-damaging way
to reach the goal?" This leads to an examination
of alternative ways of cleaning refrigerators and a search
for the least-harmful way (including, probably, vinegar-and-water
or perhaps soap-and-water). The overarching goal isn't
to inflict "acceptable" damage on humans and
the environment-the main goal is to avoid harm to the
extent that we can. Once the least-harmful way has been
selected, monitoring continues in case the decision was
flawed (always a possibility).
So here are more answers to some of the
criticisms of precaution:
Criticism #7: The precautionary principle
is based on values and emotions and not on science.
Response #7: Everything we do is based on
values. Of course the precautionary principle is based
on values, but so is the old way-the two approaches just
emphasize different values.
The precautionary principle makes one set
of values explicit- Protecting humans and ecosystems-and
puts that out front. Under the "old way" we
try to hide our values behind "science," using
scientific uncertainty as a cover for valuing short-term,
private gain and ignoring the long-term and public/environmental
consequences of our actions.
Even science starts with values. Scientific
inquiry always begins by asking a question, and the questions
that scientists choose to ask arise from particular values,
particular assumptions about what is important. So
with science and precaution, as with all of life-values
come first. There is nothing wrong with this. Indeed,
there is no way to escape it. Making values explicit helps
people understand what's really going on, and clarifies
our choices as citizens.
Advocates of the precautionary principle
definitely don't turn their backs on science, But they
also don't turn their backs on other kinds of knowledge.
Science is not the only valid way of knowing about the
world; other kinds of knowledge can be useful to decision-makers-historical
knowledge, business knowledge, spiritual knowledge, local
knowledge, community preferences, cultural values, artistic
perceptions, and so on, can all play a valuable role in
Science cannot tell us what's best for society.
Scientific experts can provide valuable information, but
when it comes to setting political goals and making public
policies, scientists have no special expertise. As the
European Environment Agency has said, "Science should
be on tap, not on top." We citizens should decide
what we really want (our goals), take all available scientific
information into account, take all the other relevant
information into account, then do our best to become wise
Who are wise decision-makers?
** Those who are willing to monitor the
consequences of their decision, to try to learn from past
** who are willing to revisit past decisions
periodically, update their assessments, and modify policies
** who favor decisions that can be reversed
if things start to go sour;
** who experiment and try to learn before
making a full-scale commitment down an unknown path;
** who consider all available alternatives,
considering both costs and benefits before proceeding;
** who involve affected parties in decisions
from the earliest stages when questions are being asked
and goals set;
** who consider intergenerational equity
in all decisions, asking whether we are saddling future
generations with costs (or diminished opportunities) that
we ourselves should be bearing;
** who ask whether justice and fairness
are enhanced by the decision;
** who ask whether the decision will increase
or decrease inequalities within and between communities;
** who ask what effect the decision will
have on the most vulnerable and least capable among us.
Criticism #8: The precautionary principle
envisions a new role for government, one without precedent
Response #8: On the contrary, government
has an ancient legal obligation to take precautionary
action, to protect the public trust.
The Public Trust Doctrine is a legal doctrine
handed down to us from Roman law, through English law,
into the law of the 13 original colonies and now the states.
The public trust doctrine asserts that the
sovereign (in our case, state government) has an inalienable
duty (a duty that cannot be denied or given away) to protect
the common wealth- air, water, wildlife, public health,
our genetic heritage, and more-which we all inherit and
own together and none of us owns individually.
As trustee, government must protect the
trust assets (nature and human health) for the trust beneficiaries
(present and future generations). Government even has
a duty to protect the trust assets against harmful
actions by the beneficiaries themselves, and so from time
to time government must limit some of the prerogatives
of private property in order to protect the common wealth
for present and future generations.
In carrying out its duty to protect the
public trust, government has a duty to anticipate harm,
to look ahead to protect the trust against impending threats.
If government waits until harm can be demonstrated beyond
doubt, then it will be too late-the trust property will
be damaged and government will have failed in its duty
The precautionary principle provides a way
for government to fulfill its responsibility to protect
the public trust, to anticipate and avoid harm, to foresee
Criticism #9: Risk assessments rely on conservative
assumptions and so they embody all the "precaution"
Response #9: Risk assessments typically
examine only a single option, not a range of alternatives.
Therefore, risk assessments don't ask the basic precautionary
question, "How can we minimize harm while achieving
Because basic data are often not available
about environment and health risks, risk assessors substitute
best professional judgments and estimates. Furthermore,
risk assessments try to compensate for unknowns
and unknowables by applying "uncertainty factors"
of 10 or 100 or 1000. As a result, two equally qualified
risk assessors working with the same basic data can reach
vastly different conclusions about risk. Peer review
of risk assessments by all stakeholders can reduce the
range of disagreement, but it remains true that the assessment
of risks can vary greatly, depending upon who is doing
the risk assessment. As the first
administrator of U.S. Environmental Protection Agency,
William Ruckelshaus, said in 1984: "We should remember
that risk assessment data can be like the captured spy:
If you torture it long enough, it will tell you anything
you want to know."
Therefore, a risk assessment of a single
option is not precautionary. Indeed, risk assessments
are often used merely to argue that a certain amount of
harm is justifiable, not to learn how much harm is avoidable.
Furthermore, instead of accepting that the
burden of producing needed information falls on the party
who is seeking to impose risks on society, risk assessors
often try to make up for the lack of basic data by applying
"uncertainty factors," as if guesswork could
adequately substitute for real knowledge. This is not
precautionary in any sense of the word.
Risk assessment might play a role in a precautionary
decision process by assessing the risks-and the benefits-of
all available alternatives. The work of risk assessors
could then be considered, along with many other factors,
in the decision.
Criticism #10: Precaution requires proof
of safety, which is impossible.
Response #10: Precaution does not require
proof of safety-it requires that the creator of risks
shall make a best effort to acquire the information needed
to assess the possible harms from the activity-an effort
that is open and subject to peer review by all affected
parties. It requires acceptance of the community's stake
in the outcome. It requires a commitment to ongoing monitoring
and open reporting as the activity unfolds, and agreeing
to pay for any harm that ensues, and taking responsibility
for remediation as needed.
But there is still no guarantee that any
particular firm will be able to make good on the financial
commitment inherent in "agreeing to pay for any harm
that ensues, and taking responsibility for remediation
as needed."If the Superfund program teaches us anything,
it teaches us that even large firms claim that they cannot
afford to remediate the problems they have created.
To deter fly-by-night firms, and to institutionalize
the principle that "the polluter shall pay,"
ecological economist Robert Costanza has proposed a "precautionary
principle polluter pays" (4P) assurance bond.[8,pgs.
209-215.] Using the "4P" approach, before a
new technology, process or chemical could be introduced,
the worst-case harm would be estimated in dollar terms.
Then the proponent of the new activity would be required
to post a bond for the full amount before startup.
Such "assurance bonds" are common
in the construction industry today, to assure that a job
will be completed on schedule and they are intended to
keep "fly by night" firms out of the construction
business where they might cut corners and endanger public
A "4P" bond effectively shifts
the burden of proof onto the proponent the burden of producing
information to show that the activity is less harmful
than was initially assumed (or, if harm becomes evident,
to pay restitution by forfeiting a portion of the bond).
A "4P" bond would also give the proponent powerful
financial incentives to reduce the worst case damages
by, for example, adopting intrinsically safer alternatives.
Criticism #11: We don't need this new way
of doing things because we're doing better than our predecessors
did. We're even doing better than we ourselves did last
year. We have new technologies that won't pollute as much
as the old technologies polluted.
Response #11: The question isn't whether
you are doing better than your predecessors, or better
than you did last year. The question is, are you doing
the best you can to protect human health and the environment?
The precautionary approach assumes you want to achieve
your own goals, and the community's goals, by the least-harmful
means available. Precaution provides a way to learn whether
you are measuring up to that standard.
 David Kriebel and others, "The
Precautionary Principle in Environmental Science,"
Environmental Health Perspectives Vol. 109, No. 9 (Sept.
2001), pgs. 871-876. Available at http://www.rachel.org/library/getfile.cfm?ID=170
 Nancy Myers, "The Precautionary
Principle Puts Values First," Bulletin of Science,
Technology and Society Vol. 22, No. 3 (June, 2002), pgs.
210-219. Available at http://www.rachel.org/library/getfile.cfm?ID=188
 Donald Ludwig, Ray Hilborn and Carl
Walters, "Uncertainty, Resource Exploitation, and
Conservation: Lessons from History," Science Vol.
260 (April 2, 1993), pgs. 17, 36. Available at http://www.rachel.org/library/getfile.cfm?ID=201
 Peter Manus, "To a Candidate in
Search of an Environmental Theme: Promote the Public trust,"
Stanford Environmental Law Journal Vol. 19 (May 2000),
pg. 315 and following pages. Available at
 James T. Paul, "The Public Trust
Doctrine: Who Has the Burden of Proof?" Paper presented
July, 1996 in Honolulu, Hawaii, to a meeting of the Western
Association of Wildlife and Fisheries Administrators.
Available at http://www.rachel.org/library/getfile.cfm?ID=190
 See Rachel's #420 at http://www.rachel.org/bulletin/index.cfm?issue_ID=705
 Ruckelshaus, W. Risk in a Free Society.
Risk Analysis. 1984; 4(3):157-162. Available at
 Robert Costanza and others, An Introduction
to Ecological Economics (Boca Raton, Fla.: St. Lucie Press,
1997). The "4P" bond was described in Rachel's
Environment & Health News #510, available at
. See also http://www.rachel.org/library/getfile.cfm?ID=310
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