[Change of PCDF and PCB concentrations in the blood of Yucheng and Yusho patients for 25 years].

The blood samples of 3 Yucheng patients collected 6-7 times from 1980 to 1993 and 5 Yusho patients collected 6-8 times from 1982 to 1993 were analyzed for congeners of polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) by high resolution gas chromatography-mass spectrometry and gas chromatography-electron capture detection. In the blood of Yucheng patients, the high concentrations of 3 PCDF congeners, 2,3',4, 4',5-penta-CB and 5 PCB congeners were eliminated at half-lives of 2.4-2.9, 1.7 and 4.1-6.1 years, respectively, while in Yusho patients, 14 years after the incident, their half-lives were converted to longer times as observed 3.2-13.4, 24.0 and 13.7-34.2 years, respectively. In the same Yucheng and Yusho patients, the half-lives of the 5 PCB congeners were about twice longer than those of the 3 PCDF congeners. PCBs are more retainable than PCDFs in human blood.