A Case Study of Risk-Based Management Decisions Using Individual Risk Appraisal. C. A. Williams, Ecology and Environment, Inc., Tallahassee, FL; A. Rawa, Ecology and Environment, Inc., Washington, DC; and A. Wiman and R. W. Freeman, Ecology and Environment, Inc., Tallahassee, FL
Human health risk assessments (HRA) provide a quantitative estimate of lifetime cancer risk and inform risk managers on the relationship of calculated lifetime cancer risks to acceptable regulatory risks (e.g., EPA’s Superfund program uses a risk range of 10-4 to 10-6). Some drawbacks to these HRAs include estimation of only population risks, failure to integrate lifestyle and medical history factors, and lack of prediction of a specific type of risk. Furthermore, the general public still typically has an alarmist view of calculated risk values and courtroom applications of population-based risk estimates are problematic. Some efforts to explain risk estimates (e.g., risks from eating peanut butter or from being exposed to high-altitude radiation) have been criticized as a trivialization. Commercially available individual health risk appraisal (IHRA) software evaluates individual lifestyle and medical factors to quantitatively predict risk for a wide variety of diseases. We have used IHRA software from the Healthier People Network to evaluate the effects of individual lifestyle choices on the risk of death and compared these risks to stochastic risk estimates. Our results indicate that unhealthy lifestyles (cigarette smoking, excessive alcohol use, poor diet) and associated risk factors (obesity, hypertension) may increase the risk of death in the next decade from 0.038 to 0.163 (a 4.3-fold increase) for 45-year-old males. Heart attack risks for men and women with only moderately elevated cardiovascular risk factors (moderate obesity, slightly elevated blood pressure, mild elevations in serum cholesterol) are about 40 times higher than the upper boundary of regulatory risk (10-4). Legal issues, such as claims of class certification based on assumed similarity of injuries, can also be addressed quantitatively. A low rate of cigarette consumption (e.g., 100 cigarettes in a lifetime) does not constitute an adequate basis for class certification, since smokers cannot be distinguished from nonsmokers in terms of their risk for smoking-attributable diseases (other than respiratory disease). For individuals with significant smoking histories (12 to 47 pack-years), risks for smoking-attributable diseases vary by as much as 4,000-fold, demonstrating that the homogeneity necessary for class certification does not exist. In summary, individual health risk appraisal can provide context to stochastic risk estimates in both regulatory and litigation settings.
Go to . . .