EPA is reasserting its confidence in the methodology it uses for comparing the toxicity of dioxin-related compounds at Superfund sites. The methodology, known as toxicity equivalent factors (TEFs), allows scientists to calculate the total risks posed by dioxin-type chemicals at waste sites. The methodology allows EPA to compare the risks of a host of dioxin-like compounds to the risks posed by the most toxic of these compounds 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD). The dioxin-like compounds include 170 so-called congeners, or dioxin-like compounds, including...