The original Japanese text can be found here.
After World War II when Japan was under Allied Occupation (1945-1952), research on atomic energy was strictly prohibited. However, in 1950 permission was granted for research on radioactive isotopes. Okano traveled throughout the country giving lectures to inform Japanese about isotopes, and became skilled in handling radioactive materials. On April 16, 1954, he traveled with his supervisor, Dr. Yamazaki Fumio, to examine the hull of the Lucky Dragon. A full month had passed since fallout had contaminated the boat, but both men were astonished to see the needle of their radiation meter swing wildly up into the danger zone. This was the first time they had detected significant radiation outside their laboratories, and it exceeded one hundred times the level occurring in nature. With the discovery that radioactive fallout had contaminated the Lucky Dragon, scientists at universities in Tokyo, Kyoto, Shizuoka, Osaka and Kanazawa began their own studies, communicating their findings by telephone.
Ikeda Nobutaka conducted research on radioactive fallout in Professor Kimura Kenjirō’s research laboratory in the Chemistry Department of Tokyo University. He also visited the Lucky Dragon at Yaizu, and collected samples of fallout-contaminated material. Returning with them to the laboratory, he and about a dozen other researchers spent the next several days and nights frantically analyzing the material out of acute concern for the Lucky Dragon’s crew.
Over the next month Ikeda and his colleagues found twenty-seven types of atomic radiation including Strontium (Sr) 89, Yttrium (Y) 90, and Cerium (Ce) 141. “We were overjoyed because knowing the radiation characteristics meant that it could be located in patients’ bodies and a way might be found to eliminate it. I can still remember how lovely the sunset looked the evening we finally finished the analyses.”
Contradicting its own denials of radioactive contamination, the U.S. government banned imports of Japanese tuna
The U.S. government was greatly alarmed by news that radiation had contaminated tuna in Japan. At the time of the Bikini tests the U.S. was importing large quantities of canned tuna from Japan. Cheap and plentiful, long-finned tuna was canned in vegetable oil.
Now the U.S. government became deeply concerned that contaminated tuna was being imported and distributed in America. Located by Professor Higuchi in the U.S. National Archives, an official U.S. government memo entitled “fish exports” was sent to Washington from the American Embassy in Tokyo on March 21, 1954, five days after the Yomiuri Shimbun reported contamination of the fishing boat Lucky Dragon. Higuchi described the memo:
The memo explained that embassy officials and representatives of the American fishing industry had warned the Japanese government to stop exports of contaminated fish. The government agreed that no fish would be exported to the United States in which radiation was detected.4
Subsequently, a member of the Atomic Energy Commission came to Japan and went to Yokohama Port. There, he ordered thorough monitoring tests for the fins and bellies of frozen tuna scheduled for export to the United States. People in Japan were outraged because, on the one hand, the U.S. government was denying that radiation from nuclear tests had contaminated the ocean or fish, yet it was suspiciously monitoring fish being exported to America.
The Japanese government refuses to pursue U.S. responsibility for contamination and supports continuation of nuclear tests
How, then, in the wake of radiation injuries to the Lucky Dragon’s crew and nuclear contamination of tuna, did the Japanese government deal with the U.S. government that had carried out the tests?
On March 17, with the Diet in an uproar over the Bikini tests, Foreign Minister Okazaki Katsuo came under persistent questioning in a session of the Lower House Budget Committee. Representative Imazumi Isamu, a member of the Socialist Party, severely criticized the Japanese government for failing to request crucial information from the U.S. about the nuclear tests. “America has inflicted radiation injuries on our country’s innocent fishermen. The treatment varies depending on what kind of bomb was detonated. A Japanese government that fails to seek this information for treating the victims is in no way worthy of representing our citizens. It is truly unforgivable.”5
Japanese scientists respond
Japanese government leaders refused to pursue U.S. responsibility for the damages inflicted by the Bikini test. However, among all government departments, the Fisheries Agency was most acutely aware of the danger. It alone planned a survey of radiation contamination in the ocean area around the Bikini atoll where the test was conducted. “The U.S. government was entirely downplaying the test’s effects,” explained Miyake Yasuo who joined the scientific advisory group organized to carry out the survey. “The Japanese government was seeking compensation for injuries to the Lucky Dragon’s crew and the major damage to our fishing industry, but conducting a survey at the site for crucial information about the radioactive contamination was absolutely essential.”
Read more at How Japanese scientists confronted the U.S. and Japanese governments to reveal the effects of Bikini H-bomb tests