The Precautionary Principle

The only common sense, responsible approach to chemical regulation that we have; the principle the chemical industry loves to hate and fights ferociously whenever laws are being formulated.


Credit: Conservationbytes

The Precautionary Principle is perhaps the most important framework for addressing issues of evaluation and regulation when evaluating chemicals and their impact on health and the environment. It has been articulated in many places, and informs the approach of virtually all anti-toxics advocates, including the scores of scientists who place themselves in this camp. It is not always an easy principle to apply, because it is open ended and requires the exercise of judgement in every case. But, given the evidence of harms we do have, and the inadequacy of extant research, no other approach makes any sense if we’re to survive.

“Environmental scientists play a key role in society’s responses to environmental problems, and many of the studies they perform are intended ultimately to affect policy,” wrote D. Krioebel and nine other scientists in ‘The precautionary principle in environmental science,’ in the National Institutes of Health’s Environmental Health Perspective, in September 2001 .

“The precautionary principle, proposed as a new guideline in environmental decision making, has four central components:

  • taking preventive action in the face of uncertainty;
  • shifting the burden of proof to the proponents of an activity;
  • exploring a wide range of alternatives to possibly harmful actions;
  • and increasing public participation in decision making.”

PP2Taken even singly, but certainly together, these components represent a fundamental departure from the approach of the chemical industry, that has insisted, in effect, that only double-blind, single-chemical studies demonstrating specific harms of specific chemicals be used to draft regulations and laws. This approach is scientifically bankrupt, for multiple of reasons. Briefly they include the fact that most chemicals have never even been studied, that macro and micro dosages bring about different kinds of adverse effects, that no human ever ingested  only one chemical – so synergies are present in every single body – and that people have very different abilities to metabolize and detoxify, depending on another set of factors: their genetic heritage, the total chemical exposure over a lifetime, their sex and their age, foetuses, babies and children being the most vulnerable. For a great discussion of the problems inherent in the ‘single-chemical’ approach, check out Jonathan R. Latham’s “Unsafe at any dose: Diagnosing chemical safety failures, from DDT to BPA.”


Credit: BioNinja,

One of the best-known manifestos of this principle – signed by a who’s who of environmental scientists – is the Wingspread Statement on the Precautionary Principle.

Here is it, followed by an great Q&A on the subject.

Wingspread Conference on the Precautionary Principle
January 26, 1998


Last weekend at an historic gathering at Wingspread, headquarters of the Johnson Foundation, scientists, philosophers, lawyers and environmental activists, reached agreement on the necessity of the Precautionary Principle in public health and environmental decision-making. The key element of the principle is that it incites us to take anticipatory action in the absence of scientific certainty. At the conclusion of the three-day conference, the diverse group issued a statement calling for government, corporations, communities and scientists to implement the “precautionary principle” in making decisions.

The 32 conference participants included treaty negotiators, activists, scholars and scientists from the United States, Canada and Europe. The conference was called to define and discuss implementing the precautionary principle, which has been used as the basis for a growing number of international agreements. The idea of precaution underpins some U.S. policy, such as the requirement for environmental impact statements before major projects are launched using federal funds. But most existing laws and regulations focus on cleaning up and controlling damage rather than preventing it. The group concluded that these policies do not sufficiently protect people and the natural world.

Participants noted that current policies such as risk assessment and cost-benefit analysis give the benefit of the doubt to new products and technologies, which may later prove harmful. And when damage occurs, victims and their advocates have the difficult task of proving that a product or activity was responsible. The precautionary principle shifts the burden of proof, insisting that those responsible for an activity must vouch for its harmlessness and be held responsible if damage occurs. The issues of scientific uncertainty, economics, environmental and public health protection which are embedded in the principle make this extremely complex. We invite your thought and conversation on these topics.


The release and use of toxic substances, the exploitation of resources, and physical alterations of the environment have had substantial unintended consequences affecting human health and the environment. Some of these concerns are high rates of learning deficiencies, asthma, cancer, birth defects and species extinctions; along with global climate change, stratospheric ozone depletion and worldwide contamination with toxic substances and nuclear materials.

We believe existing environmental regulations and other decisions, particularly those based on risk assessment, have failed to protect adequately human health and the environment – the larger system of which humans are but a part.
We believe there is compelling evidence that damage to humans and the worldwide environment is of such magnitude and seriousness that new principles for conducting human activities are necessary.

While we realize that human activities may involve hazards, people must proceed more carefully than has been the case in recent history. Corporations, government entities, organizations, communities, scientists and other individuals must adopt a precautionary approach to all human endeavors.

Therefore, it is necessary to implement the Precautionary Principle: When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically.

In this context the proponent of an activity, rather than the public, should bear the burden of proof.

The process of applying the Precautionary Principle must be open, informed and democratic and must include potentially affected parties. It must also involve an examination of the full range of alternatives, including no action.

Conference Partners

The Wingspread Conference on the Precautionary Principle was convened by the Science and Environmental Health Network, an organization that links science with the public interest, and by the Johnson Foundation, the SEHN, the C.S. Fund and the Lowell Center for Sustainable Production at the University of Massachusetts-Lowell.

Wingspread Participants:

Dr. Nicholas Ashford    M.I.T.
Katherine Barrett    Univ. of British Columbia
Anita Bernstein    Chicago-Kent College of Law
Dr. Robert Costanza    Univ. of Maryland
Pat Costner    Greenpeace
Dr. Carl Cranor    Univ. of California, Riverside
Dr. Peter deFur    Virginia Commonwealth Univ.
Gordon Durnil    Attorney
Dr. Kenneth Geiser    Toxics Use Reduction Inst., Univ. of Mass., Lowell
Dr. Andrew Jordan   Centre for Social and Economic Research on the Global Environment, Univ. Of East Anglia
Andrew King    United Steelworkers of America, Canadian Office
Dr. Frederick    Kirschenmann Farmer
Stephen Lester    Center for Health, Environment and Justice
Sue Maret    Union Inst.
Dr. Michael M’Gonigle    Univ. of Victoria, British Columbia
Dr. Peter Montague    Environmental Research Foundation
Dr. John Peterson Myers    W. Alton Jones Foundation
Dr. Mary O’Brien    Environmental Consultant
Dr. David Ozonoff    Boston Univ.
Carolyn Raffensperger    Science and Environmental Health Network
Dr. Philip Regal    Univ. of Minnesota
Hon. Pamela Resor    Massachusetts House of Representatives
Florence Robinson    Louisiana Environmental Network
Dr. Ted Schettler    Physicians for Social Responsibility
Ted Smith    Silicon Valley Toxics Coalition
Dr. Klaus-Richard Sperling    Alfred-Wegener- Institut, Hamburg
Dr. Sandra Steingraber    Author
Diane Takvorian    Environmental Health Coalition
Joel Tickner    Univ. of Mass., Lowell
Dr. Konrad von Moltke    Dartmouth College
Dr. Bo Wahlstrom    KEMI (National Chemical Inspectorate), Sweden
Jackie Warledo    Indigenous Environmental Network

Science and Environmental Health Network’s Q & A on the precautionary principle
Q. What is the precautionary principle?

A. The 1998 Wingspread Statement on the Precautionary Principle summarizes the principle this way:
“When an activity raises threats of harm to the environment or human health, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically.”
All statements of the Precautionary Principle contain a version of this formula: When the health of humans and the environment is at stake, it may not be necessary to wait for scientific certainty to take protective action.

Q. Is there some special meaning for “precaution”?

A. It’s the common sense idea behind many adages: “Be careful.” “Better safe than sorry.” “Look before you leap.” “First do no harm.”
“Precautionary principle” is a translation of the German Vorsorgeprinzip. Vorsorge means, literally, “forecaring.” It carries the sense of foresight and preparation—not merely “caution.”
The principle applies to human health and the environment. The ethical assumption behind the precautionary principle is that humans are responsible to protect, preserve, and restore the global ecosystems on which all life, including our own, depends.

Q. Why should we take action before science tells us what is harmful or what is causing harm?

A. Sometimes if we wait for certainty it is too late. Scientific standards for demonstrating cause and effect are very high. For example, smoking was strongly suspected of causing lung cancer long before the link was demonstrated conclusively. By then, many smokers had died of lung cancer. But many other people had already quit smoking because of the growing evidence that smoking was linked to lung cancer. These people were wisely exercising precaution despite some scientific uncertainty.
When evidence gives us good reason to believe that an activity, technology, or substance may be harmful, we should act to prevent harm. If we always wait for scientific certainty, people may suffer and die and the natural world may suffer irreversible damage.
Q. How do we implement the precautionary principle?

A. The precautionary principle is most powerful when it serves as a guide to making wiser decisions in the face of uncertainty. Any action that contributes to preventing harm to humans and the environment, learning more about the consequences of actions, and acting appropriately is precautionary.
Precaution does not work if it is only a last resort and results only in bans or moratoriums. It is best linked to these implementation methods:
• exploring alternatives to possibly harmful actions, especially “clean” technologies that eliminate waste and toxic substances;
• placing the burden of proof on proponents of an activity rather than on victims or potential victims of the activity;
• setting and working toward goals that protect health and the environment; and
• bringing democracy and transparency to decisions affecting health and the environment.

Q. Why do we need the precautionary principle now?

A. The effects of careless and harmful activities have accumulated over the years. Humans and the rest of the natural world have a limited capacity to absorb and overcome this harm. There are plenty of warning signs:
• Chronic diseases and conditions affect more than 100 million men, women, and children in the United States—more than a third of the population. Cancer, asthma, Alzheimer’s disease, autism, birth defects, developmental disabilities, diabetes, endometriosis, infertility, multiple sclerosis, and Parkinson’s disease are becoming increasingly common.
• In laboratory animals, wildlife, and humans, considerable evidence documents a link between levels of environmental contamination and malignancies, birth defects, reproductive problems, impaired behavior, and impaired immune system function. Scientists’ growing understanding of how biological systems develop and function leads to similar conclusions.
• Other warning signs are the dying off of plant and animal species, the destruction of ecosystems, the depletion of stratospheric ozone, and the likelihood of global warming.
Serious, evident effects such as endocrine disruption, climate change, cancer, and the disappearance of species can seldom be linked decisively to a single cause. Scientific standards of certainty may be impossible to attain when causes and outcomes are multiple; latent periods are long; timing of exposure is crucial; unexposed, “control” populations do not exist; or confounding factors are unidentified.

Q. We have lots of environmental regulations. Aren’t we already exercising precaution?

A. Precaution is at the basis of some U.S. environmental and food and drug legislation, although the principle is not mentioned by name. These laws incorporate foresight, prevention, and care, and many give regulators authority to take action to prevent possible but unproven harm. For example:
• As a precautionary measure, the Food and Drug Administration requires all new drugs to be tested before they are put on the market.
• The Food Quality and Protection Act of 1996 requires pesticides to be proven safe for children or removed. Several are being phased out.
• The National Environmental Policy Act is precautionary in two ways: 1) It emphasizes foresight and attention to consequences by requiring an environmental impact assessment for any federally funded project, and 2) it mandates consideration of alternative plans. NEPA is one of the best national examples of precautionary action.
Other laws are precautionary in intent.

The Wilderness Act sets aside certain areas as nonviolable. The Occupational Safety and Health Act imposes a general duty on employers to provide safe working conditions and workplaces. The Endangered Species Act sets the goal of protecting biodiversity. The Clean Water Act establishes strict goals to “restore and maintain the chemical, physical, and biological integrity of the nation’s waters.”
Unfortunately, precautionary action has been the exception rather than the rule in U.S. environmental policy. Instead, even laws with precautionary intent and substance have been undermined, overridden, and poorly enforced.


Q. Why have these laws failed to protect people and the environment?

A. Many regulations are aimed at cleaning up pollution and controlling the amount of it released into the environment rather than preventing the use and production of toxic substances. These laws are based on the assumption that humans and ecosystems can absorb a certain amount of contamination without being harmed. We are now learning how difficult it is to know what levels of contamination, if any, are safe.
But the greatest weakness in most conservation and toxics policies is that they are based on the expectation that science can and must provide definitive proof of harm before protective action is taken. This assumption creates a loophole in regulations, giving the benefit of the doubt to products, technologies, and development projects, even those that are likely to have harmful side effects.

Q. How does the precautionary principle change all that without bringing the economy to a halt?

A. Preventive policies encourage the exploration of better, safer, and often ultimately cheaper alternatives–and the development of cleaner products and technologies. As public awareness grows of hazards and of safer alternatives, these practices represent not only good ethics but also smart business. The markets of the Twenty-First Century will increasingly demand safe products and sustainable technologies. 
Countries that implement the precautionary principle, such as Germany and Sweden, are now exporting environmentally sound technologies. Other countries risk being left behind, with outdated, polluting facilities and technologies.
When the public has a say in the deployment of technologies, society and future generations receive more benefits and pay fewer costs in money, suffering, and diminished resources.

Q. How is the precautionary principle being used?

A. The precautionary principle should become the basis for reforming environmental laws and regulations. It can also be applied in industrial practices, science, consumer choices, education, city planning, and legal practice. Here are some examples of policies specifically based on the precautionary principle:
• San Francisco has adopted an environment code with the precautionary principle as article one. For a start, the city is applying the principle to its purchasing decisions.
• The European Union is forming a comprehensive policy, based on the precautionary principle, which would require all chemicals to be tested for their effects on health and the environment. It would put the burden on chemical manufacturers to demonstrate their products are safe. And it would give government immediate authority to regulate substances that show problems.
• Two recent treaties, the Cartagena Biosafety Protocol and the Stockholm Treaty on Persistent Organic Pollutants, invoke the precautionary principle to govern genetically modified organisms and some toxic chemicals.
• The Los Angeles Unified School District adopted the precautionary principle to limit pesticide use in schools. A number of North American cities have similar ordinances.
• Legislation has been presented in New York State applying the principle to state-funded new technologies. Massachusetts is considering precautionary principle legislation governing the phase-out of certain chemicals.
• Verizon Wireless sent a brochure in July 2001 to its US cell-phone customers describing the potential harm to children from radio frequencies emitted by cell phones. Verizon suggested that parents adopt the precautionary principle and limit children’s use of cell phones.

Q. Where can I learn more?

A. Preview the table of contents of our latest book on the precautionary principle, Precautionary Tools for Reshaping Environmental Policy, 2006, MIT Press.
Nancy Myers and Carolyn Raffensperger, editors.