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BNL 11999
Late Effects of Radioactive Fallout on the Thyroid Gland
e
in a Marshallese Population
During the past four years cases of thyreid abnormalities have
developed in a Marshallese population who were accidentally exposed to
radioactive fallout in 1954.
Before discussing this development, I would
like to briefly review the background of the accident and some of the other
effects noted in this population which are believed to have been associated
with their radlation exposure.
The accident occurred on March lst, 1954 when a thermonuclear
device was detonated at Bikini in the Pacifie proving grounds.
The yield
was larger than expected and since the fireball touched the ground, large
amounts of incinerated coral and debris were mixed with the radioactive
cloud.
An unpredicted shift in winds occurred high aloft and instead of
the cloud going in a northerly direction over the open sea, it veered to
the east dropping radioactive fallout on several inhabited islands.
The first slide shows the fallout pattern and location of
the exposed islands as related to Bikini.
The 64 Marshallese on Rongelap
atoll received the heaviest exposure and it is this group that has shown
the major radiation effects.
The island groups with their exposure status
are shown in the following table.
Summary of Fallout Effects
Group*
Rongelap
Ailingnae
Rongerik
Utirik
Composition
64 Marshallese
18 Marshallese
28 Americans
157 Marshallese
Fallout observed
Estimated gamma
dose (rads)
Heavy (snowlike)
175
Moderate (mistlike)
69
Moderate (mistilike}
78
None
14
Skin
Lesions
Numerous
Less Numerous
Slight
No skin lesions
;
or entiation
*Also exposed were 23 Japanese fishermen aboard their vessel
a
fo
gps
_ who received a sublethal dose.
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