Haws, L. Roundtable: Is it Time to Reevaluate the Toxic Equivalency Factors for PCDDs, PCDFs, and Dioxin-Like PCBs? The Use of Toxicity Equivalence Factors (TEFs) for PCDDs, PCDFs, and Dioxin-Like PCBs in Risk Assessment: Improving the Process. Dioxin 2004. September 6-10, 2004. Berlin, Germany.