The committee focused on three types of waste streams for which incineration has been used as an option for waste management: municipal solid wastes, hazardous wastes, and medical wastes. The committee structured its efforts by using an emission-to-receptor framework that is a modification of the risk assessment frameworks presented by NRC (1983, 1994). The committee's framework included consideration of the following components:

Emission characteristics and various factors that could affect emissions resulting from waste-incineration facilities.

Transformation and fate of certain emitted contaminants in various environmental media (i.e., air, water, and soil).

Contributions of incineration to environmental concentrations of contaminants.

Human populations that might be exposed to contaminants of concern, and the pathways through which exposure can occur.

Health responses that might be expected from exposures to contaminants of concern.

Characterization of relationships between waste incineration and health risks.

Other aspects of the committee's study that are not explicitly included in the emission-receptor framework are public perceptions of waste combustion and their bases, sociological considerations of incineration facility siting, and communication of information for understanding and weighing the risks associated with waste combustion.

The committee did not consider the potential health effects on organisms other than humans. In addition, the committee did not consider incineration of waste streams consisting solely of sewage sludge, wood wastes, radioactive waste, or industrial waste that is considered nonhazardous. 1 It is possible, however, that some of those types of waste are fed to a facility that incinerates municipal solid waste.

The committee also did not address, to any great degree, the effects of waste-management activities, such as waste recycling or reuse, except for how such practices might affect the characteristics of waste streams fed to an incineration facility and the resulting emissions to the environment. The committee focused its attention on wastes that have reached an incineration facility—not on the collection, storage, or transportation of wastes to a facility and not on transportation of residual ash away from a facility. However, if one were to perform

1

Various aspects related to the use of incineration for destroying the U.S. stockpile of extremely hazardous chemical agents and munitions have been addressed by another NRC committee (see NRC 1999a and related reports cited therein).

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