Investigation on Organochlorinated Compounds formed in Kanemi Rice Oil that Caused the “Yusho”
Studies on the Compounds Related to PCB (VII)
1979 年 20 巻 1 号 p. 1-9
詳細
1979 年 20 巻 1 号 p. 1-9
PCB, polychlorinated quaterphenyl (PCQ) and polychlorodibenzofuran (PCDF) were detected in Kanemi rice oil that caused the “Yusho. ” These chemicals could be attributable to the thermotransfer medium, which leaked out into Kanemi rice oil in the deodorizer, but the ratios of PCQ/PCB and PCDF/PCB in the oil were found to be extraordinarily high in comparison with those in the original thermotransfer media.
In this paper, the rice oil which was spiked with only PCB or PCB, PCQ and PCDF was deodorized using a laboratory deodorizer, and the changes of concentration of the chemicals were investigated.
1) PCQ and PCDF formation from PCB by deodorizing
The rice oil which was spiked with 10, 000ppm of purified Kanechlor 400, a Japanese commercial PCB preparation containing 48% chlorine, was deodorized in a laboratory deodorizer. The oil was saponified, extracted, washed and concentrated. The concentrated extract was then cleaned up by Florisil and alumina column chromatography to obtain the PCQ and PCDF fractions which were further perchlorinated in order to confirm the chemicalsi.
PCQ was not formed from PCB by deodorizing, but it was recognized that PCDF was formed h a small quantity, i. e., the PCDF level in the oil was 3ppb.
2) The concentration change of each component, PCB, PCQ and PCDF by deodorizing
The rice oil which was spiked with 2, 375ppm of purified Kanechlor 400, 90ppm of PCQ and 1.35ppm of PCDF was deodorized in a laboratory deodorizer.
The amount of PCB which retained in the oil decreased rapidly with rising of deodorizing temperature. When deodorized at 260-270°C, the remaining PCB in the oil was only 38ppm, namely the residual ratio was 1.6%. Less-chlorinated biphenyls than pentachlorobiphenyl evaporated more rapidly by deodorizing, and consequently the component ratio of penta- to octachlorobiphenyl in the oil increased. When deodorized in the range of 220-270°C, the PCB pattern became similar to those obtained from Kanemi rice oils that caused the “Yusho. ”
PCDF in the oil also decreased by deodorizing as well as PCB, but in lesser extent. At the same time, tri- and tetra-chlorodibenzofuran decreased, and the component ratio of penta- and hexa-chlorodibenzofuran in the oil increased.
On the other hand, it became clear that the composition and concentration of PCQ in the oil did not change by deodbrizing. Consequently, the ratios of PCQ/PCB and PCDF/PCB in the oil increased rapidly and reached gradually to the status obtained from Kanemi rice oil.
It was concluded that PCB used as the thermotransfer medium, which contained PCQ and PCDF, leaked out into Kanemi rice oil in the deodorizer, and thereafter the ratios of PCQ/PCB and PCDF/PCB in the oil might become extraordinarily high by deodorizing.
