Course Description

This course provides an overview of the evidential reasoning, methods and applications of risk assessment in understanding environmental risks and selecting effective environmental policies the protect human health. Equal attention is directed towards understanding:

• philosophical features of discourse within risk analysis, including discussions of the meaning of risk and the nature of evidential reasoning in risk assessment;
• the collection and analysis of evidence used in risk assessment;
• the physical, chemical and biological processes that underlie environmental risks;
• the treatment of uncertainty and variability;
• simple quantitative models of human health risks; and
• the performance of human health risk assessments for regulatory and other purposes.

Students are expected to learn both the mechanics of performing a risk assessment and criteria by which assessments are justified and critiqued. Emphasis is placed on scientific understanding of processes in environmental systems and the human body, and how these processes affect the nature and magnitude of risk. Additional attention is directed towards the role of scientific rationality in risk assessment, and the reasons for disagreement between risk analysts.

There are two lectures each week. Grades are based on a mid-term exam (50%) and a final exam (50%); both are take-home exams. The final exam consists of the performance of a risk assessment.

The primary text is Risk-Based Environmental Decisions: Methods and Culture by Crawford-Brown (Kluwer Academic Publishers, 1999). An electronic copy will be provided to all students.

The list below is of the topics we will cover in the class. They will be covered in the order shown, although not necessarily with equal amounts of time devoted to all topics.

Topic 1. The philosophical foundations of risk analysis. The meaning of environment, risk, and risk analysis. The nature of rationality, evidence and evidential reasoning. The development and use of logic trees in risk analysis. Readings: Chapter 1, Risk-Based Environmental Decisions.

Topic 2. The structure of risk assessment in regulatory decisions. Evolving structures such as aggregate and cumulative risk assessment. The use of risk assessment in environmental decisions. Development of risk metrics for regulatory decisions. Regulatory science and default assumptions. NOAEL, LOAEL and ample margin of safety. Readings: Chapters 2 and 5, Risk-Based Environmental Decisions.

Topic 3.Hazard Identification. Categories of evidence in hazard identification. Interpretation of epidemiological, animal and in vitro studies. Categories of human health effects. Weight-of-evidence determinations. Identification of susceptible and sensitive subpopulations. Reading: Chapter 2, Risk-Based Environmental Decisions.

Topic 4. Principles of exposure assessment. Characterizing exposure in relation to environmental systems and human populations. Identification of receptor populations. Exposure pathways and activity patterns. The four-dimensional nature of exposure. Summarizing exposure through statistical analysis. Biomarkers of exposure. Reading: Chapter 3, Risk Based Environmental Decisions.

Topic 5. Intake and uptake into the body. Particle deposition in the lungs. Intake into the G.I. tract and skin. Membrane absorption. The influence of age and lifestyle on intake and uptake. Exposure factors and definition of maximally exposed individuals. Reading: Chapter 4, Risk Based Environmental Decisions.

Topic 6. Pharmacokinetics. The relation between exposure, intake, uptake, burden, biologically significant burden, and dose. Systems analysis applied to the human body for distribution of pollutants. Biotransformation. Retention functions. Influence of age on pharmacokinetics. Biologically and physiologically based pharmacokinetic models. Reading: Chapter 4, Risk Based Environmental Decisions.

Topic 7. Pharmacodynamics and dose-response. The axiomatic basis for models of health effects. Comparing the evidence for, and predictive success of, alternative models (statistical models, state-vector models, multi-stage models). Effects of age and pre-existing conditions on sensitivity and susceptibility. Influence of dose rate, repair and cytotoxicity on risk. Conduct and interpretation of epidemiological studies, animal assays, clinical studies, and in vitro assays. Reading: Chapters 4 and 5, Risk Based Environmental Decisions.

Topic 8. Risk characterization. Uncertainty, variability and sensitivity analysis in the characterization of risk. Probability density functions and cumulative probability functions. Analytic and Monte Carlo approaches to uncertainty and variability analysis within logic tress. Readings: Chapter 6, Risk Based Environmental Decisions.

Download Preface
Download Chapter 1
Download Chapter 2
Download Chapter 3
Download Chapter 4
Download Chapter 5
Download Chapter 6
Download Chapter 7

Contacting Class Members

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