MARCH 1957 MEDICAL SURVEY OF RONGELAP AND UTIRIK PEOPLE
THREE YEARS AFTER EXPOSURE TO RADIOACTIVE FALLOUT
Background
This report presents the results of a medical
survey carried out in March 1957 on the Marshallese people who were accidentally exposed to
radioactive fallout in March 1954. The accident
occurred following the detonation of a large thermonuclear device during experiments at Bikini
in the Pacific Proving Grounds. An unpredicted
shift in winds caused deposition of significant
amounts of fallout on four nearby inhabited Marshall Islands and on 23 Japanese fishermen aboard
their fishing vessel, the Lucky Dragon. Sixty-four
inhabitants ofthe island of Rongelap, 105 nautical miles away from the detonation,received the
largest fallout exposure among the inhabited
islands: an estimated dose of 175 r whole-body
gamma radiation,beta lesions of the skin, and
epilation from contamination of the skin and
slight internal absorption of radioactive material.
The Japanese fishermen probably received a similar exposure, although estimation of their dose
is much less certain. Also 18 Rongelap people
away on a nearbyisland (Ailingnae), whereless
fallout occurred, received only abouthalfthis exposure. Twenty-eight American servicemen on an
island (Rongerik) further away received about the
same amountof radiation as did the 18 people
on Ailingnae. Lastly, 157 Marshallese on Utirik
Island, some 200 miles distant, received only
about 14 r whole-body radiation. The fallout was
notvisible on this island and noskin effects were
seen.
Theinitial findings have been reported on the
Marshallese and Americans‘ and the Japanese
fishermen.? Subsequent examinations of the
Rongelap people have been reported at the tollowing times after exposure: six months,’ one year,‘
and two years.> The present report concernsthe
examination of the Rongelap and Utirik people
three years after exposureto fallout radiation. In
addition examinations were carried out on an unexposed comparison population.
SUMMARY OF PAST FINDINGS
The following is a brief summaryof the past
findings which can be found in detail in thereferences.''?-*
Duringthe first 24 to 48 hr after after exposure,
about two-thirds of the Rongelap people experienced anorexia and nausea and a few vomited"
and had diarrhea. Ac this time manyalso experienced itching and burning of the skin and a few
complained of lachrymation and burning of the
eyes. Following this, the people remained asymptomatic until about two weeksafter the accident,
when cutaneous lesions andloss of hair developed,
due largely to beta irradiation of the skin. The
effects of the radiation can best be summarized
under three headings according to the mode of
irradiation: penetrating irradiation, skin irradiation, andinternal irradiation.
Penetrating Irradiation
The people on the island of Rongelap received
an estimated whole-body dose of 175 r gamma
radiation. Depression of peripheral blood elements occurred as follows (see Figures 7-15):
Lymphocytes fell promptlyand bv the third dav
were 55% of control values (unirradiated Marshallese) in adults, and about 25% in children.
There was only slight recovery by six months.
Through the two-year examinations the mean
values of these cells were still below the control
levels. At two years the lymphocytes were about
75 to 80% of the mean level of the comparison
population.
Neutrophils fluctuated considerably during the
first few weeks but fell gradually to a low of about
50% of control values by the sixth week after exposure; recovery was slow. At six months counts