An Analysis of Risk from Incinerator Emission Exposure. R. Harbison, K. Frantzen, R. Freeman, C. Stineman, and G. Randall, Center for Risk Analysis and Management, College of Public Health, U. of South Florida, Tampa, FL 33612; and Ecology and Environment, Inc., 368 Pleasantview Drive, Lancaster, NY 14086
The concern that emerges from the use of combustion technology is often the real or apparent production of dioxins and related compounds and subsequent potential for exposure to humans. While the risk assessment process is used to protect public health, uncertainty in the process prevents its use as a reliable indicator of the likelihood of an adverse effect occurring. Therefore, a more thorough analysis is necessary in order to effectively evaluate the risks associated with combustion technology to put the theoretical risks in perspective and limit their application to public policy. The risk assessments for several incinerator facilities were reviewed. The risks associated with exposure to combustor emissions were evaluated in comparison to common non-combustor exposures. Applying standard U.S. EPA risk assessment methodology (for comparative consistency), we estimated the risks posed by normal societal activity. For example, lifelong consumption of drinking water containing arsenic at its maximum contaminant level (50 ppb) is predicted to result in an excess cancer risk of 2.5 deaths per thousand. Moreover, dioxins in cigarette smoke (Muto and Takizawa, 1989) might yield risk outside of the CERCLA acceptable risk range (10-6 to 10-4) for a moderate smoker (50 pack-year history). These risks are compared to estimated risks from various types of waste incinerators (e.g., medical waste incinerators, the WTI incinerator, and chemical demilitarization incinerators). Much of the risks estimated to be caused by waste incinerators is due to the use of dioxin concentrations at their detection limit (or 0.5 DL) in the exposure calculations. The assumptions and safety factors used in the assessment overestimate the risks associated with incineration. In fact, so many safety factors are included as to guarantee a multiple thousand-fold protection level. In the usual course of life in the developed world the production and use of many different chemicals to manufacture the products that are ultimately consumed results in a concordant involuntary risk to others. These comparative risks are also evaluated. These risk comparisons and their implications to risk management and public policy are important features of the risk analysis process.