The association between AhR activity and POP markers in the study groups. The AhR activities are given for the four country based study groups as relation between (A) AhRag and CB-153, (B) AhRcomp and CB-153, (C) AhRag and p,p'-DDE, (D) AhRcomp and p,p'-DDE. Ln-transformed data was used. For the definition of AhRag and AhRcomp, see the legend to Table 2. RLU: relative luciferase units.