Characterization of Risks Posed by Combustor Emissions

• Published in: Drug and chemical toxicology (New York, N.Y. 1978) N.Y. 1978), 1999-01, Vol.22 (1), p.221-240
• Main Authors: Rice, Glenn, Swartout, Jeff, Brady-Roberts, Eletha, Reisman, David, Mahaffey, Kate, Lyon, Bradford
• Format: Article
• Language: English
• Subjects: Air Pollutants - toxicity; Animals; Humans; Industrial Waste - adverse effects; Methylmercury Compounds - toxicity; Models, Chemical; Risk Assessment - methods; Risk Factors; Toxicology - methods; United States; United States Environmental Protection Agency; Vehicle Emissions - adverse effects
• ISSN: 0148-0545; 1525-6014
• DOI: 10.3109/01480549909029734

ABSTRACT Risk characterization is the final step of the risk assessment process as practiced in the U.S. EPA. In risk characterization, the major scientific evidence and "bottom-line" results from the other components of the risk assessment process, hazard identification, dose-respdnse assessment, and exposure assessment, are evaluated and integrated into an overall conclusion about the risks posed by a given situation. Risk characterization is also an iterative process; the results of a specific step may require re-evaluation or additional information to finalize the risk assessment process. Risks posed by atmospheric emissions are an example of an involuntary human health risk which typically receives a great deal of public attention. Characterization of the risks posed by atmospheric emissions typically requires the use of mathematical models to evaluate: I) the environmental fate of emitted pollutants, 2) exposures to these pollutants, and 3) human dose-response. Integration df these models results in quantitdtive risk estimates. The confidence in a quantitative risk estimate is examined by evaluating uncertainty and variability within individual risk assessment components. Variability arises from the true heterogeneity in characteristics within a population or an event; on the other hand, uncertainty represents lack of knowledge about the true value used in a risk estimate. U.S. EPA's 1997 Mercury Study will illustrate some aspects of the risk characterization process as well as the uncertainty and variability encountered in the risk assessment process.