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An Overview of Risk Assessment
Bernard D. Goldstein, MD
University of Pittsburgh
Graduate School of Public Health
An Overview of Risk AssessmentObjectives of this Lecture
• The student will have an understanding of:– The definition of risk assessment and its four
components, including their scientific basis.
– The basic issues in environmental policy that are responsible for the genesis and use of risk assessment.
– The key strengths and weaknesses of risk assessment as a public policy tool
– The role of risk assessment as an interface between environmental science and public policy
What Are the Components of Risk Assessment?
• Hazard identification
• Dose-response evaluation
• Human exposure evaluation
• Risk characterization
Better Things Through Chemistry
5,000,000 known chemicals (1,000,000 in 1945)
70,000 chemicals in widespread use
1,500 new chemicals in use yearly
Annual bioassay capability about 500/year
Scientists manipulate formulae to match the real world.
Policymakers manipulate the real world to match formulae.
Comparative Risk of Death
Number of
Deaths / Year Lifetime Risks
Motor vehicle accidents
46,000 1/65
Home accidents
25,000 1/130
Lung cancer deaths in smokers
80,000 1/12
Risk
Assessment
Risk
Management
Research and
Data Collection
The Three Laws of Toxicology
• The dose makes the poison
• Chemicals have specific effects
• Humans are animals
Hazard Identification
The determination of whether a particular chemical or agent is or is not causally linked to a particular health effect.
Probably Not Carcinogenic4
Not Classifiable3
Possibly Carcinogenic2B
Probably Carcinogenic2A
Carcinogenic to Humans1
Weight of Evidence
IARC Overall Evaluation of Carcinogenicity to Humans
Dose Response Evaluation
The determination of the relation between the magnitude of exposure and the probability of occurrence of the health effect in question.
Dose-Response Curve
ResponseObservable Range
Range of Inference
Dose
Structure of DNA
Human Exposure Evaluation
• How many people will be exposed?
• Through which routes?
• Who is exposed?
• What is the magnitude, duration, and timing of the exposure?
Continuum for the Emission of and Exposure to a Contaminant and the Expression of a Health Effect
P.J. Lioy, Env. Sci. & Tech. Submitted 1990
SourceEmission
Transport andTransformation
Accumulationin
Environment
HumanContact
Exposure
Potential Doseto the Body
Health EffectEarly
Expression ofDisease
BiologicallyEffective Dose Internal Dose
EliminationAccumulation
TransformationBioavailability
Risk Characterization
The description of the nature and often the magnitude of the human risk, including attendant uncertainty.
Risk Assessment
Dose-Response Assessment
Risk Characterization
Exposure Assessment
Hazard Identification
Dose-Response
Assessment
Risk Characterization
Exposure Assessment
Hazard Identification
Regulatory Decision
Control Options
Non-Risk Analysis
Risk Assessment Risk Management
The Three Laws of Toxicology
• The dose makes the poison
• Chemicals have specific effects
• Humans are animals
Uses of Risk Assessment for Management Decision Making
• National Regulations:– Environmental standards (air, water, hazardous waste,
etc.)– Food safety (chemical contaminants, additives, pathogens)– Manufacturing and production (pharmaceuticals,
pesticides, etc.)
• International Trade / WTO SPS Agreement:– Food products (Safety Assessment and Acceptable Daily
Intake [ADI])– Animals and animal products– Plants and plant products
Range of Expert Judgment
X XX XX X
Range of Expert Judgment
XXX XXX
Communication of Science
In the presence of uncertainty, the technique usually relied upon to ascertain the current state of knowledge is:
CONSENSUS by SCIENTISTS
BALANCE by JOURNALISTS
CONFRONTATION by LAWYERS
CATNIP PRINCIPLE
Cheapest Available Technology Not Involving Prosecution
Margin of Safety
Is it Risk Assessment or Risk Management?
Components of decision:
What is strength of positive data?
What is strength of negative data?
Is uncertainty qualitative or quantitative?
What is the clinical significance of risk?
Problems and Limitations of Risk Assessment
1. The process by which policy and science are mixed together in a risk assessment is poorly understood.
2. Its ability to provide a “Bright Line” has been overstated by risk assessors and overused by regulators and lawmakers.
Problems and Limitations of Risk Assessment
(continued)3. The data quality objective for the different goals
and types of risk assessment is poorly understood.
4. There is often a substantial gap between the data quality objective of the decision maker and the degree of complexity of the assessment, with unnecessary analyses confusing and delaying response.
Problems and Limitations of Risk Assessment
(continued)5. Risk assessment often obscures the substantial
gap between the data needs for good public health decision making and the paucity of available data.
6. Risk characterization should be extended beyond a probabilistic statement of cancer risk to include considerations of other health and non-health endpoints.
Problems and Limitations of Risk Assessment
(continued)
7. Risk assessment is secondary prevention rather than primary prevention.
Risk Assessment and Risk Management is a 3 Step Process
• Science Policy producing Risk Assessment Guidelines
• Risk Assessment
• Risk Management
Risk Assessment Guidelines:Use and Intent
• Provide consistency
• Establish data quality objectives
• Assure technical quality
• Clarify scientific assumptions
• Allow flexibility to be transparent
• Provide public with “Road Map”
Precautionary Principle Described
in the Rio Declaration:Nations shall use the precautionary approach
to protect the environment. Where there are
threats of serious or irreversible damage,
scientific uncertainty shall not be used to
postpone cost-effective measures to prevent
environmental degradation.
Definition of the Precautionary Principle
(Cynical Version)
The Precautionary Principle is a nebulous doctrine developed by Europeans as a means to erect a trade barrier against any item that can be produced more efficiently elsewhere
RISK ASSESSMENT AND THE PRECAUTIONARY PRINCIPLE
Three different views• The Precautionary Principle is already
incorporated in Risk Assessment
• The Precautionary Principle should be incorporated into Risk Assessment
• The Precautionary Principle and Risk Assessment are completely antithetical
Framework is Conducted:
• In collaboration with stakeholders.
• Using iterations if new information is developed that changes the need for or nature of risk management.
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