[Change of PCDF concentrations in the blood of Yusho patients in recent ten years].

The blood of 16 Yusho patients sampled from 1982 (14 years after the incident) to 1992 were analyzed for congeners of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) by high resolution gas chromatography-mass spectrometry and gas chromatography with electron capture detection, respectively. Biological half-lives of PCDFs and PCBs were estimated by following the change of blood concentrations of the Yusho patients in the equation of 1-compartment model. The biological half-lives of 2, 3, 4, 7, 8-penta-CDF and 1, 2, 3, 4, 7, 8-hexa-CDF in 8 individuals varied from 6.0 to 76 years with median 11.7 years and from 4.8 to 26.5 years with median 7.0 years, respectively. The half-lives of 1, 2, 3, 4, 6, 7, 8-hepta-CDF in 4 individuals varied from 2.1 to 15 years. Concentrations of PCBs in 13 individuals were estimated to be slowly decreased and increased with several years half-life in about half-and-half numbers.