Abstract
The concentrations of polychlorodibenzofuran (PCDF) in two KC-400s which were used as thermotransfer medium was 8.4 (277ppm) and 15.5 (510ppm) times higher than that in original KC-400 preparation. These PCDFs were mainly composed of tetra-, penta- and hexa-chlorodibenzofuran. The component ratio of higher chlorinated PCDFs increased in thermotransfer medium which was used for long period under high temperature. The PCDF components in thermotransfer media were similar to that of Kanemi Rice Oils which caused “Kanemi Yusho, ” but the ratios of PCDF versus PCB concentration in thermotransfer media were lower one to two order in comparison with that of the Kanemi Rice Oils.
On the other hand, when KC-400 sealed in glass ampules was heated at 180 to 300°C, a little PCDF was genetated from PCB. When heating temperature was rised to 360°C, PCDF formed clearly, and its concentration became 2 to 2.8 times in comparison with that of non heating KC-400. Stainless steal acted catalytically on the PCDF formation. It became clear that water also accelerated the PCDF formation. However, PCDFs in heated KC-400 were mainly composed tri- to penta-chlorodibenzofuran, and the component was different from that of PCDF in Kanemi Rice Oils.
