1983 年 18 巻 1 号 p. 3-10
The purpose of the present study was to estimate a biological half-life of iodine in normal Japanese thyroid for the calculation of the thyroid dose from iodine-129 with a long physical half-life. The Japanese takes stable iodine through sea food in a more considerable amount than the Caucasian who is assumed to be the Reference Man recommended by ICRP. It can be shown by medical research in thyroidology that the iodine metabolism between the Japanese and the Caucasian is different owing to the amount of the ingested stable iodine. Furthermore, in the Japanese the thyroid releases inorganic iodine since it takes up iodine more than physiologically required to produce thyroid hormone.
We calculated the biological half-life of iodine for both the Japanese and the Caucasian by using a five compartment model. The following results were delivered. The biological half-life in the Japanese was approximately 40 days, which was in agreement with the values reported before. On the other hand, that of the Caucasian was 130 days nearly equal to the Reference Man.