Environmental Health
XV. Risk Assessment
Shu-Chi Chang, Ph.D., P.E., P.A.
Assistant Professor1 and Division Chief2
1Department of Environmental Engineering
2Division of Occupational Safety and Health,
Center for Environmental Protection and Occupational Safety and Health
National Chung Hsing University
Friday, June 22, 2007
Outline
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Introduction
Applications
Qualitative risk assessment
Quantitative risk assessment
Accident situations
Risk management
Introduction
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Definition of risk
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Risk assessment
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Personal
Environmental health
What can go wrong
How likely
What consequence
Risk management
Uncertainties
Applications
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Two basic concepts
Cost/benefit analysis
Still hard to communicate
Comparative risks
Comparative risks
Qualitative risk assessment
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Budgetary constraint
Qualitative risk assessment
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Qualitative characterization where health risks are
identified but not quantified
Qualitative risk estimations where chemicals are
ranked or classified by broad categories of risk
Semi-quantitative approaches where effect levels
were used in combination with uncertainty factors
to establish “safe” exposure level
EPA’s five categories of toxic agents
ATSDR’s public health assessment
ASTDR’s public health
assessment
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10 key substances: (1) lead, (2) arsenic, (3) mercury, (4)
vinyl chloride, (5) benzene, (6) cadmium, (7)
polychlorinated biphenyls, (8) chloroform, (9)
benzo(b)fluoranthene, (10) trichloroehtylene.
7 priority health conditions: (1) birth defect and
reproductive disorder, (2) cancers, (3) immune function
disorders, (4) kidney dysfunction, (5) liver dysfunction, (6)
lung and respiratory diseases, and (7) neurotoxic
disorders
5 categories of risks: (1) urgent public health hazards, (2)
public health hazards, (3) indeterminate public health
hazards, (4) no apparent public health hazards, and (5)
no public health hazards.
Quantitative risk assessment
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Hazard identification
Dose-response evaluation
Exposure assessment
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The chemical and physical characteristics of the toxic agent
Identification of the person to be protected
Recognition of the difference in the exposure measured and
the dose that will actually be received by the exposed
individuals
Risk characterization
Components of QRA
Accident situations
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Risks associated with accidents
Four steps
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Accident scenario development and
screening
Consequence assessment
Uncertainty and sensitivity assessment
Regulatory-compliance assessment
Risk management
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Acceptable levels of risk
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Risk communication
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Trigger levels for environmental or occupational
controls
Superfund site remediation: risk based decision
Key decision factors
Inadequate manner of scientific community
Examples: days of life lost, per year of life saved,
EPA’s rules of risk communication
Reporting risk distribution
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Reflect the uncertainty associated with QSA
Examples: key principles
1 in 1,000,000 risk of death
1 in 1,000,000 risk of death
1 in 1,000,000 risk of death
Days of life lost
Expenditures per year of life
saved
EPA’s seven rules of risk
communication
Key principles of risk assessment
Final exam reminders
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Cover all the materials taught in this term
~50% from the homework
Open-book, 2 hours
No discussion but you are allowed to share resources
You may leave the classroom after you sign the attendance
sheet.
Return your final exam to Room 502, Civil and Environmental
Building, NCHU before noon, 06/29/2007.
Hand in the exam write-up in person to Dr. Shu-Chi Chang
Your final score will be posted on the bulletin board before July
2, 2007.