Characterization of Risks Posed by Combustor Emissions

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-response 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: 1) the environmental fate of emitted pollutants, 2) exposures to these pollutants, and 3) human dose-response. Integration of these models results in quantitative 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.

Monitoring dioxins and furans in the vicinity of an old municipal waste incinerator after pronounced reductions of the atmospheric emissions

“…In recent years, intense local opposition to incineration has notably increased as a result of the fears surrounding their potential environmental impact and the risks to human health from the emissions of a number of organic and inorganic products. [1][2][3][4] Among the emission products of municipal solid waste incinerators (MSWI), and due to their great toxicological potential, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are of particular concern. 5 Once emitted into the atmosphere, PCDD/Fs are dispersed throughout the environment, and because of their semivolatile and hydrophobic properties, they accumulate in organic rich media.…”