9/29/08 ESPP-781 Where does risk come from? A story from a small state in upstate New York

9/29/08 ESPP-782 National Research Council, “Red Book” Model of Risk Analysis (1983)

9/29/08 ESPP-783 Steps in Formal Risk Analysis Research Hazard identification Exposure assessment Risk characterization Risk communication Risk management

9/29/08 ESPP-784 Analytic Methods for Toxic Chemicals and Their Limitations Short-term tests (problem: reductionism) Bioassays (problem: interspecies extrapolation) –choice of test animals –routes of exposure –dose-response issues Epidemiology (problem: confounding factors)

9/29/08 ESPP-785 Social Construction of Risk Models What causal understandings are built into the risk assessment model? –E.g., Cancer begins with a single mutation. Which parameters are important? –E.g., For cancer causation, what matters is level of exposure, chemical structure, DNA repair. What measures and methods are used to characterize those parameters? –E.g., structure-activity studies, animal studies, biological uptake from environment

9/29/08 ESPP-786 Model: From Mouse to Man

9/29/08 ESPP-787 Biases that may overstate risk Conservative assumptions in QRA –use of most sensitive species –considering all routes of exposure –use of high-dose testing Low-dose extrapolation (ignoring possible mechanisms and thresholds) Tilt toward human-made hazards (e.g., pesticides vs. “natural carcinogens”)

9/29/08 ESPP-788 Biases that may understate risk Synergistic effects (multiple exposures) Vulnerable or non-standard populations Tilt toward “natural” rather than social or behavioral causes –ignoring behavior as an element of risk Bias toward “known” scenarios and available evidence

9/29/08 ESPP-789 Risk Management Strategies Zero risk (no animal carcinogens in food) De minimis risk (<10 -6 lifetime cancer risk) Safety (no observable effect level or NOEL) Acceptable risk (regulatory standard) Risk tradeoffs –risks vs. benefits (disease vs. income, speed, connectivity, choice) –risks vs. risks (epidemic vs. drug reaction)

9/29/08 ESPP-7810 Ethical Issues in Risk Analysis Preventive policy: no “body counts” No human experimentation –But is it permissible to test low-level exposures on consenting subjects? Ethical treatment of animals How conservative should the analyst be?

9/29/08 ESPP-7811 The Analytic-Deliberative model of Risk Analysis