The Precautionary Principle

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The Precautionary Principle

• Managing theoretical risks in public health

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Policy Problem

• The blood system is confronted with the potential
  new infectious threat from vCJD
• Must take measures to protect against this
  theoretical risk
• Must balance theoretical reduction in supply that
  could be caused by developing a policy

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Background
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CJD

• Most common human TSE
• Due to effects of prion
• 4 Forms
• classical
• familial
• iatrogenic
• variant

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Classical CJD

• develops in 6th to 8th decade of life
• rapidly progressing dementia
• cerebellar symptoms
• death within 3 to 12 months

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Variant CJD

• Variant CJD first identified in 1996 in UK
• average age of onset 27
• presents with behavioural symptoms
• invariably fatal, average duration of symptoms of
  14 months

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Diagnosis/Treatment

• No blood test
• No treatment

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Policy Challenge
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vCJD and the blood supply

• First theoretical infectious risk to challenge
  the Canadian blood system since the Krever
  Inquiry

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• UK Events
• Concerns soon developed that this condition may
  be blood transmitted
• led to a UK decision to import certain blood
  product requirements from other countries

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• Canadian officials immediately began considering
  whether Canada should use blood from individuals
  who had traveled to the UK

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What information is needed to develop policy?

• Risk of transmission of vCJD
• Reduction in blood supply of any policy
• How much reduction in the blood supply could the
  sytem sustain

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Risk of Transmission of Classical CJD Case
control studies
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Risk of Blood Transmission of vCJD

• No epidemiological studies
• Theoretical Risk
• higher prion concentration
• affinity for lymphoreticular system
• existing model for peripheral transmission (oral)

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Impact of Donor Deferral Policies

• Full deferral
• 22 reduction
• 1 month deferral
• 10 reduction
• 6 month deferral
• 3 reduction

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Sustainability of Blood Supply Reduction

• Blood system had been able to sustain a 3
  reduction in supply in the past

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What Policy should be instituted?
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Options

• No policy should be instituted
• vCJD is a theoretical risk, there is no
  epidemiological evidence of harm
• A partial policy should be instituted
• balances reducing the risk of vCJD with potential
  harm caused by reducing the blood supply
• Full policy should be instituted
• even 1 day in the UK puts you at risk

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Canadian Response

• Canadian blood system embarked upon risk
  assessment analysis
• conducted a systematic evaluation of the impact
  on supply of a donor deferral policy versus the
  potential health benefit of such a policy.

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Policy Decision

• August 1999, policy-makers officially announced
  that individuals who had traveled to the UK for
  6-months between the years 1980 and 1996 would be
  deferred from donating blood

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• Is this Evidence-Based Decision-Making?

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Factors Influencing Policy Process
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Importance of Value Systems on Interpretation of
Scientific Information

• Role of the Precautionary Principle

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Limitations of evidence

• In 1986 BSE is discovered in the UK
• no epidemiological evidence exists of harm,
  however there is a theoretical risk of
  transmission
• UK chose not to take actions to halt spread of
  BSE
• important health impact, enormous financial
  impact, undermined confidence in public health

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• In 1980s concern emerged about potential blood
  transmission of HIV and Hepatitis C
• no epidemiological evidence exists of harm,
  however there was a theoretical risk of
  transmission
• Canada chose not to take full measures to protect
  blood supply from HIV, Hep C
• enormous health and financial impact, undermined
  confidence in blood system

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• Both government responses criticized for not
  taking precautionary measures

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• the safety of the blood supply is an aspect of
  public health, and, therefore, the blood supply
  system must be governed by the public health
  philosophy, which rejects the view that complete
  knowledge of a public health hazard is a
  prerequisite for action.
• Justice Krever

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The Precautionary Principle

• The precautionary principle emerged out of the
  European environmental movement of the 1970s and
  has its roots in the German concept of Vorsorge
  or foresight.

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• The principle reflects a recognition of the
  limitations of scientific models to accurately
  describe complex issues pertaining to
  environmental harm or health risk

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Impact

• Since the time of its introduction, the
  precautionary principle has had a substantial
  impact on environmental policy
• It has been incorporated into the 1992 Rio
  Declaration on Environment and Development and
  the Maastricht Treaty Establishing the European
  Community

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Definition

• The precautionary principle essentially states
  that complete evidence of risk does not have to
  exist to protect individuals and society from the
  risk
• Better to be safe than sorry
• An ounce of prevention is worth a pound of cure

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• 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.
• Wingspread Statement

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• 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.
• Rio Declaration

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Interpretations of the Principle

• Stronger interpretations
• burden of responsibility on the proponents of
  potentially harmful measures
• Weaker interpretations
• burden of proof on those arguing the possibility
  of harm

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Core Concepts

• (1) advocating anticipatory action to prevent
  harm
• (2) shifting some of the burden of proof to the
  proponents of new technologies to demonstrate
  safety

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• (3) advocating a consideration of all
  alternatives to a new technology including doing
  nothing
• (4) incorporation of all affected parties in the
  decision- making process of adopting a new
  technology

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Problems with Precaution
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• Policy makers have had difficulty in agreeing on
  how much or how little evidence is required to
  trigger a precautionary action and on the role of
  the scientific process when the principle is
  utilized

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• The variability in the interpretation of the
  principle has led to accusations that the
  principle has been used as a mechanism to
  introduce trade protectionism.

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• The principle has also been accused of
• producing over regulation
• denying the public the benefits of new
  technologies
• arousing unnecessary fear in the public about
  theoretical risks

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Applications

• Primarily has been used in the environmental
  sector
• Increasingly being used in the health sector
• Implications of applying an environmental
  measure to the health sector has not been fully
  examined

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Challenge of Balancing Competing Risks

• recognizing that in the application of the
  precautionary principle strictly to health, that
  there are some potential problems in exercising
  restraint when it involves a therapeutic
  product, the absence of (which) may in itself
  have a risk consequence to a patient population

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Is the Precautionary Principle Useful in Public
Health?
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Double Edged Sword

• Environmental Sector
• Balance benefits to health and the environment
  versus economic and technological losses
• Health Sector
• Balance benefits to health against possible
  health consequences

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Examples of inappropriate Precaution

• DDT and environmental harm
• Banned because of environmental harm based on
  animal evidence
• Increase in malaria deaths
• Chlorine and cancer
• Peru banned chlorine because of carcinogenic
  fears
• Cholera outbreak followed
• GMOs and biodiversity
• EU banned import of GMOs due to theoretical
  fears of harm
• Zambia refused large donation of GMOs in the
  presence of famine

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Proposed Solutions

• Proportionality
• Non-discrimination
• Consistency
• Examining costs and benefits
• Subject to review
• Assigning responsibility for producing scientific
  evidence

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How can the Precautionary Principle be applied?

• 4 mechanisms of application of the Precautionary
  Principle

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The precautionary principle and evidence-based
policy

• The fundamental question related to application
  of the precautionary principle is what is an
  acceptable level of uncertainty of risk
• How much systematic and random error are policy
  makers willing to accept

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Follow-up to vCJD Donor deferral decision
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Subsequent events

• Extended to all of Europe
• UK residency period reduced to 3 months
• Canada and US have first cases of vCJD
• Animal studies suggest blood transmission is
  possible
• Four case reports of transfusion transmission

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Relationship of Evidence to Policy
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Evaluation of Precaution in the vCJD donor
deferral decision
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Conclusions

• The precautionary principle in its broadest
  context is a useful and necessary tool to policy
  makers.
• In order for it to be an effective policy guide
  further refinements to the principle are needed
  and a precautionary principle specific for the
  health sector needs to be developed.

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Questions ?