バイオアッセイ法によるヒトのトリチウム排泄に関する分析

抄録

On the basis of many human tritium metabolic data accumulated in the Intense 14MeV Neutron Source Facility OKTAVIAN of Osaka University, Japan, until now, the characteristics of the measured data have been analyzed for bioassay samples of urine, exhaled water and water distilled from urine. It has been found that the tritium concentration of exhaled water is equal to that in water distilled from urine. A new method has been developed to follow up each metabolism of two chemical forms, that is, free water tritium (FWT) and organically bound tritium (OBT) in urine. In case of repeated tritium intake, it was found that the tritium concentration could be approximated by single exponential function corresponding to the fastest excretion component for about 50 days after each intake. In this approximate method, the biological half-life of second intake exceeded compared with that of first intake. The distribution ratio of FWT and OBT components changed at the next intake compared with the previous intake. Consequently, the ratio of the OBT component increased and brought the apparent increase of the biological half-life.