of 14, which was greater than the TCDD induction factor for that sample. The standard deviation of the responses of the three replicates for each sample extract varied between 7 percent and 15 percent. All the TCDD EC50 values were between 6 and 18, except P1-1 (21.6) and P1-2 (20.7). The luciferase activity in the lowest TCDD concentration group was similar to the value of the solvent control in all the sample extracts (Hurst et al., 2004; Gustavsson et al., 2007).