Applying Modern Metrics for Risk Assessments: Use of QALYs for Drinking Water Risk Analyses and Risk Communications. T. Harvey, USEPA, Cincinnati, OH
For nearly 20 years risk assessors have appropriately used probability estimates to measure environmental risks using the 1983 NRC paradigm. While relatively few, peer reviewed risk characterizations have come from these efforts, often risks have been communicated in terms of likelihoods of no effects over life times in the form of numerical calculations like RfD/RfCs in the range of (base 10) E - 4-8. Such numerical representations are not well generally appreciated nor well understood by the general public. In the process of developing improved risk methodology for quantitative comparative risk analysis and decisions (SAB12/98,2/99), the USEPA’s National Center for Environmental Assessment (NCEA) has used a more informative metric for comparing and communicating risk trade offs for disinfection and microbial dynamics in drinking water. The Quality of Adjusted Life Years (QALY) is a stakeholder’s (affected persons) based metric; widely used in the human health community; and facilitates combining of very different health effects (infectious diarrhea, repro-developmental, cancers) into one useable quantum. Using QLAYs as a numerator and interventions cost as the denominator, cost effectiveness ratios which compare multiple barrier choices can readily be supplied. Such cost effectiveness ratios do not make decisions alone but allow for more informed choices by risk managers including the public at large. Although the use of Comparative Risk Methodology and QALYs started in EPA in early 1996 with the M-DBPs challenges, the application of these methods and metrics can readily be applied to both simple and complex environmental issues. This presentation will also identify some additional environmental applications using this public health approach including placed-based evaluations.
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