The amount of that three of 14 workers irradiated in a nuclear accident at uranium-processing firm JCO Co. were exposed to is estimated to have been at least eight sievert, doctors said Thursday evening.
This is equivalent to the amount of gamma rays measured 700-800 meters from ground zero when an atomic bomb was dropped on Hiroshima in 1945.
About half of all people exposed to radiation of 4 sievert or higher face the possibility of death within 30 days.
Two of the workers were suffering symptoms of serious radiation poisoning, such as dehydration, and are listed in extremely serious condition, the doctors added.
Gen Suzuki, a doctor at the National Institute of Radiological Sciences in Chiba, to which the workers were airlifted, said the conditions of the two seriously affected workers is “more serious than those of the crew members of Fukuryu Maru No. 5,” a Japanese fishing boat that was accidently irradiated by a U.S. hydrogen bomb test on the Bikini Atoll in March 1954.
The 23-strong crew was exposed to severe radiation after their boat strayed into the test area. One of them later died of a disease believed caused by radiation from the test.
Yasuhito Sasaki, head of the institute, emphasized that doctors at the institute would “do their utmost” to save their lives.
One of the workers, Hisashi Ouchi, 35, temporarily lost consciousness immediately after the accident but has since been able to respond to questions from doctors, officials of the institute said.
Masato Shinohara, 39, is suffering from diarrhea and is repeatedly asking the doctors for water, they added. Both Ouchi and Shinohara are reportedly showing symptoms of consciousness disorder.
Nanao Kamada, a professor at the Research Institute for Radiation Biology and Medicine at Hiroshima University, said Ouchi and Shinohara are believed to be suffering from acute radiation symptoms and that it is difficult to provide proper treatment for them.
Kamada, who examined the blood tests of the three workers, said the third man, Yutaka Yokokawa, 54, is also in a serious condition.
Sodium-24, a radioactive substance, was detected in the vomit of all three, the officials said.
The number of leukocytes in the three rose by two to four times the normal level, according to the institute.
The ratio of lymphocytes in white blood corpuscles, which averages 40 percent among ordinary people, has dropped below 10 percent, and the figures for Ouchi and Shinohara are as low as 2 percent.
Kamada said the degree of radiation the three were exposed to is high, estimating the amount the two critically injured workers absorbed was between 8 to 10 sievert, judging from their lymphocyte count and overall condition.
A marrow transplant is needed for patients suffering from serious acute radiation damage, but Kamada said giving such treatment to the two would be difficult.
Judging from their skin, the two were exposed to radiation that includes not only gamma rays, but alpha rays as well, he said.
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