On the fallout by nuclear explosion experiment and the radioactive iodine in animal organism

Radioactive iodine (mainly 131I, 132I, 133I, and 135I) was measured with fallout, cow milk, human urine, and thyroid glands (human and cattles) after the first nuclear explosion experiment in China. Analysing method was determined by placing emphasis on rapidity and perfect separation from other nuclides. The detectable limit employing this method was about several p Ci. The identification of radioactive iodine was performed with a simultaneous counting type β - ray spectrometer, and 131I, 132I, and 133I were identified by their half lives. 131I in cow milk increased from around the 4th day after the experiment, and it had been detected for a month continuously, the maximum amount being 437 p Ci/l. In thyroid glands, 131I was detected for 100 days in a milch cow, the maximum being 88, 1p Ci/g, while it was somewhat low in Japanese cows and pigs. 131I in the thyroid gland of a human infant (accidentally died after 12 days) was 1.29p Ci/g. 131I in human urine was 6.3p Ci/l on the 7th day. (Kobatake, H.)