National Annual Dioxin Emissions Estimate for Hazardous Waste Incinerators

Reducing emissions of polychlorinated dibenzo-p-di-oxins and dibenzofurans, commonly known as di-oxins, is a high priority for environmental regulatory bodies throughout much of the world. In the United States, Section 112 (c)(6) of the Clean Air Act (CAA) requires the Environmental Protectio n Agency (EPA) to identify and control emissions from sources that are responsible for at least 90% of the overall emissions of seven targeted hazardous air pollutants, including dioxins.¹ On April 19, 1996, the EPA proposed Maximum Achievable Control Technology (MACT) Standards for Hazardous Waste Combustors² (HWCs). In that preamble, the EPA estimated annual dioxin emissions from the nation's hazardous waste incinerators (HWIs) to be 79 grams expressed as 2,3,7,8 tetrachloro dibenzo-p-dioxins (TCDD) international toxic equivalents (ITEQs). However, early EPA dioxin emission estimates from medical waste incinerators and cement kilns were significantly overestimated;^3-5 so, the following independent national dioxin emissions estimate for HWIs was prepared. This estimate corrects the errors in the EPA's HWI emissions database, uses an updated inventory of HWIs in the United States, and applies statistical imputation techniques that take maximum advantage of the limited dioxin emissions data for HWIs.