Concentrations and profiles of tri- through octa-chloro-substituted polychlorinated naphthalene (PCN) congeners were determined in eighteen technical polychlorinated biphenyl (PCB) mixtures including Aroclors, Kanechlors, Clophens, Phenoclors, Sovol, and Chlorofen. PCNs were found in all the PCB mixtures at concentrations ranging from 5.2 to 730 μg/g. Concentrations of PCNs in Aroclor and Kanechlor mixtures were greater than those of polychlorinated dibenzofurans (PCDFs) present as impurities in these technical PCB preparations. Composition of PCN homologues varied among PCB mixtures. In general, highly chlorinated PCB mixtures contained greater percentages of more-chlorinated naphthalene congeners. Concentrations of PCNs varied by 3-fold among three different lots of Aroclor 1254. On the basis of measured concentrations of PCNs in PCB mixtures and global production estimates of PCBs, PCNs emitted from the use of PCBs was estimated to be 169 tons, which is less than 1% of the production of technical PCN mixtures such as Halowaxes. 2,3,7,8-Tetrachlorodibenzo- p -dioxin equivalents (TEQs) contributed by PCNs in technical PCB mixtures were less than those estimated for coplanar PCB congeners and PCDFs.
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Yamashita et al. (2000) studied this question.
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