Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and non-ortho chlorine substituted PCBs (Co-PCBs) are widespread contaminants of the global environment. PCDDs, PCDFs and Co-PCBs all act at least in part via a common mechanism of biological action In addition, some of PCDD and PCDF isomers, and Co-PCBs are extremely toxicใ Therefore, they have been the subject of much concern in the environmental field in variouscountries.