Follow-up survey of dioxins in the blood of Yusho patients (in 2001)

Follow-up survey of the blood concentration of polychlorinated dibezo-p-dioxin (PCDDs), polychlorinated dibenzofuran (PCDFs), Non-ortho-coplaner PCBs (Non-Co-PCB), and Mono-ortho-coplaner PCBs (Mo-Co-PCB) in Yusho patients is very important for their health control. We determined the blood concentration of these dioxin-like isomers in 78 blood samples collected in 2001 using by a high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) equipped with a solvent-cut large volume injection system (SCLV). The accelerated solvent extraction (ASE) method was employed for the treatment of blood samples. The method employed here can allow a reduced amount of blood collecting from Yusho patients compared with the conventional method. In typical Yusho patients (Group A of PCB pattern), the mean TEQ concentrations of PCDDs, PCDFs, Non-Co-PCBs, and Mono-Co-PCBs in blood collected in 2001 were 36, 260, 9.3, and 64 pg-TEQ/g lipid, respectively. As well, the toxic contribution of PCDDs, PCDFs, Non-Co-PCBs, and Mono-Co-PCBs in typical Yusho patients (Group A of PCB pattern) were 10, 70, 3, and 17% of the total TEQ value, respectively. The toxic contribution rate of PCDFs TEQ was still at high levels in relation to total TEQ in typical Yusho patients as mention above. The Yusho patients showing B pattern also had the same A pattern contribution rate. In the patients of group C, however, the mean blood levels of dioxin TEQ in 2001 was two times those of the normal controls determined in 2000 in Fukuoka prefecture. As well, the contribution rates were similar to those of normal subjects, although some patients in this group showed a high toxic contribution rate of PCDFs TEQ in relation to total TEQ. Thirty-three years had passed since the Yusho accident, and the total blood concentrations of PCDFs in the blood of Yusho patients were still higher than those of normal subjects. Among the different groups of PCB patterns, the concentration of 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF and 1,2,3,6,7,8-HxCDF showed significant differences. These findings indicate that these isomers are not metabolized in the human body since traces of them continued to be detected in these patients since they had been contaminated by the rice oil in the original incident.