Toxicity equivalency values for polychlorinated biphenyl mixtures

For aquatic, avian, and mammalian species, dioxin equivalency values (TEQs) were computed for Aroclor, Clophen, Kanechlor, Chlorofen, Sovol, Delor, Phenoclor, and Chinese polychlorinated biphenyl (PCB) mixtures by using World Health Organization toxicity equivalency factors (TEFs) and compound-specific compositional data for PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) for the individual mixtures. The TEQs were similar across the different PCB product lines for mixtures of similar chlorine content. Depending on the PCB mixture, the polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in the mixture contributed anywhere from 0 to 96% of the total TEQs, and the impact of PCDD/Fs was greatest for the fish TEQs. In comparison to the dioxin-like PCBs, few measurements have been performed for PCDD/Fs in the commercial PCB products.