Abstract
Uptake and loss of radioactive iodine by marine organisms were studied in the artificial seawater in which the concentration as well as chemical forms of both stable and radioactive iodine were controlled. The concentration factors of radioactive iodine by these organisms were clearly dependent upon the concentration of stable iodide ion in the culture media while the concentration of stable iodate ion did not affect the uptake and loss of radioactive iodine. It was observed that the higher the concentration of iodide ion was in the culture media the shorter the biological half-life of radioactive iodine became, and thus the lower the concentration factor resulted in.
