The Precautionary Principle

Managing theoretical risks in public health

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

Background

CJD

Most common human TSE Due to effects of prion 4 Forms

classical familial iatrogenic variant

Classical CJD

develops in 6th to 8th decade of life

rapidly progressing dementia

cerebellar symptoms

death within 3 to 12 months

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

Diagnosis/Treatment

No blood test

No treatment

Policy Challenge

vCJD and the blood supply

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

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

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

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

Risk of Transmission of Classical CJD – Case control studies

Kondo, 1982 0.56 (0.06-5.56)

Harries-Jones, 1988

0.77 (0.44-1.50)

Esmonde, 1993 0.68 (0.39-1.20)

Van Dujin, 1998 0.56 (0.37-0.97)

Collins, 1999 0.89 (0.57-1.40)

Risk of Blood Transmission of vCJD

No epidemiological studies Theoretical Risk

higher prion concentration affinity for lymphoreticular system existing model for peripheral transmission

(oral)

Impact of Donor Deferral Policies

Full deferral 22% reduction

1 month deferral 10% reduction

6 month deferral 3% reduction

Sustainability of Blood Supply Reduction

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

What Policy should be instituted?

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

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.

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

Is this Evidence-Based Decision-Making?

Sabatier-Lomas Policy Analysis Framework

A schematic of the contextual influences on the decision-making process

Social Problem/Issue

Power Relationships

Persuasion

Epistemiology, paradigms

Information

InstitutionalStructure for

Decision-Making

ProducersResearchers

InstitutesPollsters

PurveyorsMedia

AdvocatesNetworks

Knowledge

Formal Structure

ExecutiveLegislative

Bureaucracy

Informal Structure

Policy BrokersCoalitions

StakeholdersCitizens

Values

IdeologiesViews about

what ought tobe

BeliefsCausal

assumptionsabout what is

InterestsResponses to

incentivesand rewards

Policies

Factors Influencing Policy Process

Importance of Value Systems on Interpretation of Scientific

Information

Role of the Precautionary Principle

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

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

Both government responses criticized for not taking precautionary measures

“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

The Precautionary Principle

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

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

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

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”

“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

“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

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

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

(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

Problems with Precaution

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

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.

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

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

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”

Is the Precautionary Principle Useful in Public Health?

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

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

GMO’s and biodiversity EU banned import of GMO’s due to theoretical fears of harm Zambia refused large donation of GMO’s in the presence of

famine

Proposed Solutions

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

scientific evidence

How can the Precautionary Principle be applied?

4 mechanisms of application of the Precautionary Principle

Mechanism Example

Strong Precaution

Introduction of full precautionary measure to eliminate perceived risk

European Commission position

on importing genetically

modified foods

Intermediate Approach

Introduction of partial precautionary measure designed to balance risk

prevented by implementation of precaution versus risk created by

introduction of precaution (risk-management approach)

US and Canadian policy on

blood donations from

individuals at risk of vCJD

Weak Precaution

Delayed introduction of precautionary measure until mechanisms

instituted to protect against health risk created by introducing

precautionary measure

Stockholm Convention position

on DDT

Evidence-Based Approach

Deferral of precautionary measure until more definitive

epidemiological evidence becomes available

US FDA position on phthalates

in cosmetic products

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

Level of acceptable certainty of causal association

Low HighExposure Wide Narrow

Outcomes Serious Treatable/reversible

Cost of risk factor removal Inexpensive Expensive

Negative effects (e.g. health) of risk factor removal

Limited Serious

Follow-up to vCJD Donor deferral decision

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

Relationship of Evidence to Policy

Year Policy Evidence

1996 vCJD discoveredtheoretical transfusiontransmission risk suspected

1997 UK announces decision to recall bloodcomponents/plasma derivatives fromindividuals later diagnosed with vCJD

1998 UK chooses to import plasma tomanufacture fractionated products

France and UK introduce universalleukoreduction

1999 Canada and the US introduce donordeferral policies

2000 France introduces UK donor deferralpolicy

Preliminary report of sheep tosheep transfusion transmission ofBSE

2001

2002 Confirmation of sheep to sheeptransfusion transmission in bothpre-clinical and clinical animals

2003 UK decision to import fresh frozen plasma for use in patients born after January 1996

Human case report of vCJD inrecipient of transfusion from avCJD donorEfficiency of BSE transmissionIn primates, efficiency of BSEtransmission demonstrated to beat least as efficient via transfusiontransmission as by the oral route

Growth of expenditure on blood and blood products in Canada

0

100

200

300

400

500

600

700

1998-1999 1999-2000 2000-2001 2001-2002

Years

In M

illi

on

s o

f $

Blood operations

Fractionated products

Captive insurance

Total

Advantages Disadvantages

Protects against recallslong term cost benefitprotection against shortagesavoids recipient notificationchallenges

Potential protection from alarge scale health riskMaintains trust in bloodsystemMaintains trust in publichealth

Short term cost No definitive evidence ofriskDiscourages donorsReduction in blood supply

Evaluation of Precaution in the vCJD donor deferral decision

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.

Questions ?