Environmental Health XV. Risk Assessment

Shu-Chi Chang, Ph.D., P.E., P.A.Assistant Professor1 and Division Chief2

1Department of Environmental Engineering2Division of Occupational Safety and Health,

Center for Environmental Protection and Occupational Safety and Health

National Chung Hsing University

Friday, June 22, 2007

Outline

Introduction Applications Qualitative risk assessment Quantitative risk assessment Accident situations Risk management

Introduction

Definition of risk Personal Environmental health

Risk assessment What can go wrong How likely What consequence

Risk management Uncertainties

Applications

Two basic concepts

Cost/benefit analysis Still hard to communicate

Comparative risks

Comparative risks

Qualitative risk assessment

Budgetary constraint Qualitative risk assessment

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

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

Hazard identification Dose-response evaluation Exposure assessment

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

Risks associated with accidents Four steps

Accident scenario development and screening

Consequence assessment Uncertainty and sensitivity

assessment Regulatory-compliance assessment

Risk management

Acceptable levels of risk Trigger levels for environmental or

occupational controls Superfund site remediation: risk based

decision Key decision factors

Risk communication Inadequate manner of scientific community Examples: days of life lost, per year of life

saved, EPA’s rules of risk communication Reporting risk distribution

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

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.