THE PRECAUTIONARY PRINCIPLE:

Policy Responses to Environmental Health Problems

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Carolyn RaffenspergerTed Schettler

Exploring Links to Environmental Diseases

December 5, 2003

Why we need the precautionary principle

• Humans have caused major global change  • Some change has serious implications

– Hole in the ozone layer– global climate change– collapse of marine fisheries– alteration of major biogeochemical cycles, including carbon,

nitrogen, water, metals– synthetic chemicals contaminate virtually all wildlife and

humans

• The magnitude of human caused change is unprecedented 

Why the precautionary principle?: additional perspectives

(the world is big and complex)

• Assessing cumulative, systems level or interactive effects is difficult.

• Surprises have occurred too frequently ( Ex. CFCs and the hole in the ozone layer).

• Future generations have interests and needs that are difficult to protect with some decision-making strategies

• Many current choices have high decision stakes because of the scale at which they are made. (Global choices have global consequences.)

An additional public health perspective

• Patterns of illness and disease are changing: e.g., asthma, neurodevelopmental disorders, incidence of some malignancies and birth defects; chronic, degenerative diseases.

What is the precautionary principle?

Wingspread Statement: “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.”

Wingspread statementJan., 1998

1. People have a duty to take anticipatory action to prevent harm. 

2. The burden of proof lies with the proponents, not with the public. 

3. Before using a new technology, process, or chemical, or starting a new activity, people have an obligation to examine "a full range of alternatives.” 

4. Decisions applying the precautionary principle must be "open, informed, and democratic" and "must include affected parties."

Common elements of the precautionary principle in international treaties

 

All formulations include:

 

1) Threat of harm

 

2) Lack of scientific certainty

 

3) Action to prevent harm

The precautionary principle incorporates both science and

ethics

– Ethics and values

• Do no harm

– Science

• What we know

• How we know

• What we don’t know

Values underlying the precautionary principle

1) Respect - for the needs and rights of this and future generations as well as others who cannot speak for themselves

2) Humility - towards the natural world and our ability to understand it through science

3) Democracy - giving people a voice in matters that affect their lives

4) Responsibility - government’s public trust responsibility to manage the commonwealth for this and future generations.Individuals’ and their institutions’, including industry, obligation to take responsibility for their actions in the world.

History of the precautionary principle

•  The use of Vorsorge in Germany•  Sweden

– Goal setting– “Sunsetting” chemicals– Presence of chemical sufficient; evidence of harm

not necessary

•  Treaties•  International Joint Commission•  Wingspread•  California (EPA and San Francisco)

Harm

  1) Serious 

2) Irreversible 

3) Cumulative

4) Broad spatial and temporal dimensions

5) Easily avoidable

Scientific uncertainty

• Uncertainty about cause or magnitude

• Uncertainty, indeterminacy, ignorance– Value of more data– Unpredictability of complex systems– Asking the right questions

Kinds of uncertainty

• Statistical

• Model

• Fundamental

Statistical uncertainty

• Easiest to reduce or quantify

• Results from not knowing the value of some variable at a particular point in space or time, but knowing, or being able to determine, the probability of a given value

Model uncertainty

• Results from not fully understanding the relationships between variables in a system

• May know that a particular outcome is possible, but probability of that outcome is difficult to predict; may be indeterminant.

Fundamental uncertainty

• Increasing indeterminacy

• Partially results from ignorance

• Ignorance of ignorance a big problem (we don’t know what we don’t know)

• Fail to ask the right questions

Science and the precautionary principle

• Kinds of errors and error bias

• “Proof”

• What do we need to consider in order to say that something “causes” something else?

• The limits of science

Kinds of errors when assessing “safety”

• Type 1 (false positive)—conclude that something is harmful when it is not

• Type 2 (false negative)—conclude that something is safe when it is not

• Type 3—the right answer to the wrong question

Error bias

• Scientific studies are usually interpreted to favor type 2 over type 1 errors

• This is because we have chosen not to conclude that evidence is “significantly positive” without it being “strong”

• ? Should the interpretation of “science” for establishing health- and environmentally- protective policies favor Type 1 errors? Who should decide?

How do we know what “causes” a disease?

• Hume (1700s)—we don’t perceive or see causes; we observe sequences and events and infer causes

• Robert Koch (1890)—Koch’s postulates for infectious disease

• Bradford Hill (1960’s)—the “Hill” criteria for causation

Hill criteria for causation in epidemiology

• Consistency of findings

• Strength of association

• Biological gradient (dose-response)

• Temporal sequence (“cause” before effect)

• Biologic plausibility (mechanism)

• Coherence with established facts

• Specificity of association

Comments from Bradford Hill

• “None of my criteria can bring indisputable evidence for or against a cause and effect hypothesis and none, except for time sequence, can be required as a sine qua non”

• “All scientific work is liable to be upset or modified by advancing knowledge. That does not confer upon us a freedom to ignore the knowledge that we already have, or to postpone the action that it appears to demand at a given time.”

Cigarettes and lung cancer—evidence for causation

• 1945—Ochsner—Incidence rises together

• 1950—Doll & Hill—case-control study

• 1953—Wynder—tar causes cancer in mice

• 1954—Follow up studies show association, and that greater exposure > greater risk

• 1990s—biological mechanism(s) described (genetic factors; mutations)

“Proof”

• Scientific “proof” depends on the kind of study and the criteria that are agreed upon to establish proof

• What constitutes “proof” is a mixture of scientific, social, and political factors

When is “proof” difficult to establish?

• Non-specificity-– many exposures “cause” multiple diseases; e.g

smoking – many diseases have multiple “causes”; interactions

• Long latent period between exposure and disease• Windows of vulnerability: exposure is most

hazardous when it occurs at a particular time• Exposures are ubiquitous; no “control” population• Unidentified susceptible populations mixed in

with the general population

Precautionary Action

• Anticipatory and preventive• Increases rather than decreases options• Can be monitored and reversed• Increases resilience, health, integrity of

whole system• Enhances diversity (one size does not fit all)

Shifting the burden of proof

• Industry has an obligation – to test their product (ask the right questions and use the right

scientific disciplines)– heed early warnings – seek safer alternatives – publicly disclose information about harm.– pay for damage and restoration.

• Shifting the burden of proof does NOT mean that industry has to prove absolute safety.

• Shifting the burden of proof does mean that the environment and public health get the benefit of the doubt.

Implementing the precautionary principle

  1) Establish a general duty to act with precaution 

2) Set goals 

3) Use science wisely

Establish a public interest research agenda

Use the right discipline.

Use multiple disciplines.

4) Enhance information flows

5) Create early warning systems

Implementing the precautionary principle (cont)

6) Shift the burden of responsibility/proof (Locate responsibility in the system)

7) Create new torts and other legal mechanisms

8) Choose the least harmful alternative 9) Engage in democratic decision-making

processes10) Explicitly incorporate values

Can we say “yes” using the precautionary principle?

 1) Ongoing monitoring

 

2) Performance bonds

 

3) Alternatives assessment (Similar to an EIS under NEPA)

 

4) Adaptive management

June 17th the San Francisco Board of Supervisors adopted the precautionary

principle as city and county policy

“every San Franciscan has an equal right to a healthy and safe environment. This requires that our air, water, earth, and food be of a sufficiently high standard that individuals and communities can live healthy, fulfilling, and dignified lives. The duty to enhance, protect and preserve San Francisco's environment rests on the shoulders of government, residents, citizen groups and businesses alike.”