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 6 th to 8 th 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, ( ) Harries-Jones, ( ) Esmonde, ( ) Van Dujin, ( ) Collins, ( )

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?

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

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 LowHigh ExposureWideNarrow OutcomesSeriousTreatable/rever sible Cost of risk factor removalInexpensiveExpensive Negative effects (e.g. health) of risk factor removal LimitedSerious

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 YearPolicyEvidence 1996vCJD discovered theoretical transfusion transmission risk suspected 1997UK announces decision to recall blood components/plasma derivatives from individuals later diagnosed with vCJD 1998UK chooses to import plasma to manufacture fractionated products France and UK introduce universal leukoreduction 1999Canada and the US introduce donor deferral policies 2000France introduces UK donor deferral policy Preliminary report of sheep to sheep transfusion transmission of BSE Confirmation of sheep to sheep transfusion transmission in both pre-clinical and clinical animals 2003UK decision to import fresh frozen plasma for use in patients born after January 1996 Human case report of vCJD in recipient of transfusion from a vCJD donor Efficiency of BSE transmission In primates, efficiency of BSE transmission demonstrated to be at least as efficient via transfusion transmission as by the oral route

AdvantagesDisadvantages Protects against recalls long term cost benefit protection against shortages avoids recipient notification challenges Potential protection from a large scale health risk Maintains trust in blood system Maintains trust in public health Short term cost No definitive evidence of risk Discourages donors Reduction 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 ?