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UNCLASSIFIED
Part V
Biology and Medicine
STUDIES OF THE ATOMIC BOMB CASUALTY COMMISSION (ABCC) IN JAPAN
(ONCLASSIFIED)
Eighty thousand atomic bomb survivors from Hiroshima and 15,00@ from Nagasaki were
within 2,000 meters of the blast hypocenter. In accordance with plans nlade during the 19561958 period, certain of those survivors as well as special control populftions have been es-
tablished as the “Master Sample” for close study. Results of these studies to date indicate
that radioactivity induced in or acquired by the survivors is probably nfgligible or nonexistent.
Dosimetry relative to distance from hypocenter is becoming relatively better known as physical dosimetric studies continue. Other results of the studies to date ar# summarized below.
Congenital Effects
Neither still births nor major congenital abnormalities occurring
the irradiated groups
were found to be in exceas of those occurring in controls. Negative findings also resulted from
study of birth weights, simple anthropometric measurements, and postgatal death and infant
mortality rates. With this size population there would be 95 chances out of 100 that a doubling
of the natural rate of these genetic effects would have been detected, Hbwever, there were
some alterations in sex-ratio of these children {a shift to a preponderahce of males) suggesting that there had been effects on the reproductive celis of the parents.
Cataracts and Other Eye Damage
Overt lesions, visible by the ophthalmoscope, were found in a totaJof only 154 survivors
in the two cities. Loss of visual acuity due to the cataracts was small,fwith all but four patients achieving effective vision with appropriate corrective lenses.
he four instances the
visual defect was sufficient to require operation.
°
A measurable reduction in visual acuity has been found in childre who were 7 to 10 years
of age at the time of exposure. The causes of this weakness have not been determined.
Leukemia
Leukemia is a recognized effect of irradiation in experimental a
Hiroshima an increased incidence of leukemia became noticeable in 19 48 and reached a peak
in 1950-52: a total of 122 cases has occurred in residents of Hiroshim h. The incidence rate
has decreased since then, but is still somewhat higher in the exposed gopulation than in the
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