Revision 1
March 19, 1998
by Radiation, Science, and Health, Inc.,
Edited by J. Muckerheide

1.2.5
Weapons and Facility Releases

1.2.5.2
Public

1.2.5.2.2
Marshall Islanders and 'Lucky Dragon' Fishermen

"On 1 March 1954, a hydrogen bomb test was performed on Bikini Island, and 23 Japanese fishermen, 18-39 years old, were exposed to ‘lethal’ radioactive fall-out (about 1 mCi/g by a crude estimate). A brief description of the event and its effects is given here because these men can be regarded as having received a level of radiation intermediate between that of the Hiroshima-Nagasaki atomic bombings and that of the Chernobyl accident (see Kumatori et al. 1980, for details).

"Estimates of whole-body doses of gamma rays from the external fall-out, which were received during the first two weeks up to 14 March when they returned to Japan, were 200-295 rad for 11 fishermen, 325-395 rad for five, 415-475 for three, 545-575 rad for three and 670 rad for one. The acute effects of chronic irradiation at these doses were estimated to be approximately equivalent to those of a single, acute irradiation with half of the doses, i.e., total acute doses of 80-320 rad. Additional doses of radiation in the thyroid, on the basis of radioactive iodine nuclides incorporated, were estimated to be 230-550 rad.

"One fisherman with hematological disturbances (anemia, leukopenia and thrombopenia) and hepatitis died 206 days after the accident, and one with ascites caused by cirrhosis died 21 years later. No malignant disease has been observed in the remaining men. Follow-up studies of peripheral leukocytes and platelets from the exposed fishermen were carried out from the time they returned to Japan. Average leukocyte and platelet counts were markedly depressed for about two years after the exposure, recovered gradually, reaching normal levels two to five years after the exposure, and then showed several excesses for about two years thereafter. More than 20 years after the exposure, the average leukocyte counts were slightly depressed. In two fishermen exposed to high doses, neutrophil counts were depressed continuously for 25 years when compared with the counts on the first day after their return to Japan."