General
Plant
History
RCRA Corrective
Action
Investigation
Activities
CERCLA
Creek Soil & Sediment Removal Action
Information Evaluation
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Risk Assessment
What is Risk?
- Risk is defined as the probability that a substance
or situation will produce harm under specified conditions.
Risk is a combination of two factors:
• The probability that an adverse event will
occur
(such as a specific disease or type of
injury); and
• The consequence of the adverse event.
- Risk arises from exposure and hazards.
What is Risk Assessment and Risk Management?
- Risk assessment is the systematic, scientific characterization
of potential adverse effects of human or ecological
exposures to hazardous agents or activities.
- Risk management is the process of identifying,
evaluating, selecting, and implementing actions
to reduce risks to human health and to ecosystems.
The goal of risk management is scientifically sound,
cost-effective, integrated actions that reduce or
prevent risks while taking into account social, cultural,
ethical, political, and legal considerations.
- Risk management goals should be used to guide risk
analyses.
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Exposure Scenarios
- Where are the contaminants?
- Who is potentially exposed
to the
contaminants?
- How might individuals
encounter contaminants?
- What are the potential
exposure routes?
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Health Effects
- Human carcinogens
vs.
non-carcinogens
- What health effects
does the chemical cause?
- Are different effects seen
for acute, short-term, and long-term
exposures?
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Dose Estimates
- The amount of a chemical that enters the body (dose) depends on:
• Concentration of the
chemical
• Intake rate
• Frequency
• Duration
- Decisions on whether to take preventive measures are based on “reasonable maximum exposures”.
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Dose-Response Relationship
- Relationship between the extent of an adverse effect and the amount of a chemical that enters the body.
- In general, the dose must be high before effects can occur.
- Severity of effects generally increases with increasingly higher doses.
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What are Acceptable Risk Levels?
- Cumulative site cancer risk of 1 in 10,000 to an
individual and noncancer hazard index less than 1,
based on Reasonable Maximum Exposure under current
and future land use (U.S. EPA 1991).
- Chemical-specific standards that define acceptable
risk levels can be used to determine whether an exposure
is associated with an unacceptable risk (U.S. EPA
1991).
- Background lifetime cancer risk in the United States
is
approximately 4 in 10, or 0.4 (American Cancer Society
1999).
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