Dioxin toxicity varies among the congeners International Toxicity Equivalency Factors (tef)for PCDDs and PCDs Congener PCDD series PCDF series 2378 1( defined)0.1 12378 0.5 0.05 23478 0.5 123478,0.1 0.1 123678, (also include 234678 congener) 23789 12346780.01 0. 01(also include 1234789 congener) octachloro.001 0.001 The teFs allow the conversion of various congener concentrations into a single toxicity equivalent quantity (teq)Dioxin toxicity varies among the congeners Congener PCDD series PCDF series 2378 1 (defined) 0.1 12378 0.5 0.05 23478 0.5 123478, 123678, 123789 0.1 0.1 (also include 234678 congener) 1234678 0.01 0.01 (also include 1234789 congener) octachloro 0.001 0.001 International Toxicity Equivalency Factors (TEF) for PCDDs and PCDFs The TEFs allow the conversion of various congener concentrations into a single toxicity equivalent quantity (TEQ)