Risk Management: A Conceptual Introduction Tee L. Guidotti Occupational Health Program University of...
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Transcript of Risk Management: A Conceptual Introduction Tee L. Guidotti Occupational Health Program University of...
Risk Management: Risk Management: A Conceptual A Conceptual IntroductionIntroduction
Tee L. Guidotti
Occupational Health Program
University of Alberta
Dimensions of Risk Management
• Risk perception
• Risk communication
• Risk control– structural change– reduce exposure– reduce potential loss or liability
• Risk anticipation
• Risk comparison
What is Risk - Really?
• A conceptual abstraction - “risk” does not exist per se
• Risk is a description of the behaviour of a system, either in past or predicted
• Risk reflects characteristics of the system, subject to change
• Risk is fundamental to change or adaptation
• All society is about mitigating risk
Levels of Risk
Legal standard of certainty
Allowable scientific error
Clinical complications
Public health
(e.g. vaccine safety)
De minimis
0.5
0.05 (p value)
0.01 - 0.1
10-5 - 10-4
10-5
Risk Perception
Risk Perception
• Public view of risk may not match that of experts
• People tend to estimate risk best in the middle of the range - they distort the extremes
• Risk perception is laden with values learned in society and the family
• Risk perception is culturally determined
• Risk is perceived as good in many contexts
Risk Communication
Cardinal Rules for Risk Communication
• Accept, involve public as legitimate partner• Plan carefully and evaluate performance• Listen to the audience• Be honest, frank and open• Coordinate, collaborate with other credible sources• Meet the needs of the media• Speak clearly and with compassionAfter Covello; originally prepared for U.S. EPA.
Risk control
• structural change– engineering and environmental change– replacement
• reduce exposure– protection– isolation
• reduce potential loss (mitigate effects)• reduce potential liability
Achieving Risk Control
• Market incentives
• Regulation
• Voluntary compliance– may involve mutual coercion– role of guidelines– indirect regulation
• Cultural norms
Risk Control through Regulation
Regulatory Options
Market, informedchoice
Tobacco products
Ban/Prohibition Conspicuous hazardCost/Benefit Consumer product safetyRisk/Benefit Occupational standardsRisk/Risk Drug regulationTechnology-driven Air emissions, BACTAcceptable risk Environmental standards
Standards v. Guidelines
Standards• Legal authority usually
delegated• Binding• Mandatory compliance• Enforceable• Universal application• Consultation process
Guidelines• Authority usually
negotiated• Advisory• Voluntary compliance• No sanctions• Discretionary• Multistakeholder process
Examples of Standards - US
PEL OSHA TWA, STEL
NAAQS EPA Air quality
Emissions regs State, regionalAQMDs
Site-specific,subject to trading
Water qualitystandards
EPA Bodies of water
Discharge limits State, localauthorities
Site-specific
Consumer products CPSC, FDA, FSQS Quality and safety
Radiationprotectionstandards
NRL Based on cum dose
Examples of Guidelines - US
REL NIOSH Recommended toOSHA
TLV ACGIH Recommended,private status
Standards and Guidelines in Canada
OEL, specificstandards
Occupationalhealth
Standards
Air quality guidelines Federal-provincial
Guidelines(formerlyobjectives)
Cdn Drinking WaterGuidlines
Federal-provincial
Guidelines
Emissions, effluentstandards
Provincial Standards
Remediation CCME Guidelines
Establishing Exposure Standards
• Occupational v. environmental (assumptions of vulnerability)
• General benchmark required– risk based– non-degradation (historical)– reference level, NOAEL/safety factor– technology-driven
• Appropriate model for extrapolation
How Standards Are Set - U.S. EPA as an Example
Two Models for Standard Setting
• Noncarcinogens (direct effects model)
• Carcinogens (stochastic model)
These standards-setting models flow logically from the risk assessment models used for each.
Model: Non-Carcinogens
• Standards for non-carcinogens typically assume a toxicologic exposure-response relationship– based on known exposure-response slope– identify NOAEL, extrapolate to humans– safety factors (uncertainty factors)
• Acceptable risk is below chronic toxicity level for most vulnerable subgroups
RfD = NOAEL/(UF1 … Ufn)
NOAEL,NOEL
No observed (adverse) effectlevel
LOAEL,LOEL
Lowest observed (adverse)effect level
RfD,RfC
Reference dose or concentration(for airborne exposures)
UF,MF
Uncertainty factor, “modifying”factor, (safety factor)
Safety Factors (US EPA)
UF1 Intraspecies variation 1 – 10
UF2 Potential + -interaction 1 – 10
UF3 Route of exposure adjustment 1 – 10
UF4 Fraction of intake attributableto source
Variable
UF5 F = 1 for NOAEL,F = 10 for LOAEL
1 or 10
UF6 Interspecies extrapolation,F = 1 for humanF = 10 for animal data
1 or 10
Model for Carcinogens
• Stochastic model, derive maximum likelihood estimate or UCL of frequency-response slope
• Derive unit cancer risk, q1*
• Individual lifetime cancer risk =exposure slope
• Adjust allowable exposure to de minimis risk level ( 10–5)
Implications of Model for Carcinogens
• Because risk level is preset, little flexibility• Safety factors do not apply• Low-dose extrapolation: on-going debate• Tends to drive standards-setting in mixtures of
carcinogenic, non-carcinogenic agents– benzene in Cdn drinking water guidelines– benzene drives BTEX-based evaluations– PAHs drive CCME guidelines
Historical Derivation of Standards
• Consensual process or majority of an authoritative group
• Based on review of the evidence
• Considerable debate in camera
• Issues of role and conflict of interest
• Problem of disinterested expert
• Disillusionment and opening of process
Risk Anticipation
• New idea, in evolution
• Anticipate risk before it becomes a management problem
• Requires internal culture of skepticism
Risk Comparison
• A systematic process of consultation in an open, multistakeholder process– expert panels– public(s)
• Iterative process in open discussion
• Consensus on magnitude of risks
• Consensus on priorities and ranking of risks
Risk Comparison
Benefits• Consensus, once achieved,
is solid• Broadly inclusive• Educates constituencies• Direct guidance for public
priorities, e.g. budgets• Provides framework for
NGO participation
Drawbacks• Very time consuming• Easily hijacked• Requires active outreach to
constituencies• NGOs may lead public• NGOs may not be
representative of public opinion