The accumulation of data from these surveysis
becomingincreasingly voluminous. Since condi-
tions have not been favorable for performance of
extensive statistical analyses or use of electronic
computing procedures to store and manipulate the
data, the annual survey reports published by this
Laboratory are made as complete as possible. This
report, therefore, includes a considerable amount
of raw data, much of it in appendices, so that
others may have an opportunity to make further
calculations if desired.
This report also contains a brief addendum on
the vegetation of Rongelap Island.
Summaryof Past Findings
Reports have been published on the findings of
surveys made at the following times after exposure: initial examination,' 6 months,’ | year,’ 2
years,* 3 years,° and 4 years.° Thefollowing isa
brief summaryof the findings previously reported.
During the first 24 to 48 hr after exposure,
about % of the Rongelap people experienced
anorexia and nausea. A few vomited and had
diarrhea. Many also experienced itching and
burning of the skin, and a few complainedoflachrymation and burning of the eyes. Following this,
the people remained asymptomatic until about 2
weeksafter the accident, when cutaneouslesions
andloss of hair developed, due largely to beta irradiation of the skin. It was apparent when the
people werefirst examined, a few daysafter exposure, that the lymphocytes were considerably depressed and thatsignificant doses of radiation had
probably been received. In addition to the wholebody dose of radiation andthe betairradiation of
the skin, radiochemical analyses of the urine
showed that measurable amounts of radioactive
material had also been absorbed internally. The
effects of the radiation can best be summarized
underthree headings according to the modeof exposure: penetrating irradiation, skin irradiation,
andinternalirradiation.
PENETRATING IRRADIATION
‘ The changes in the peripheral blood of the more
heavily exposed Rongelap people whoreceived
175 r will be reviewedin the section on hemato-
logical examinations(see Figures 33, 35, and 38,
and Appendices | and 2). The changes in the
Ailingnae and Utirik groups were similar butless
marked. Certain unexplained fluctuations have
occurred from yearto year in the peripheral blood
levels of the comparison populationsas well as of
the exposed groups. Depression of the peripheral
blood elements as represented by mean population levels occurred as follows.
Lymphocytesfell promptly and by the third day
were about 55% of the control values in adults,
and slightly lower in children. There was only
slight recovery after six months. At 2 years, although further recovery was evident, the mean
values of these cells were still found to be below
the comparison population levels (75 to 80%). At
3 years the mean lymphocyte counts wereslightly
below those of the comparison population. At 4
years the mean level appeared to be aboutthe
sameas that of the comparison population, but
many counts remained lower.
Neutrophil levels fluctuated considerably during the first few weeks but fell gradually to a low
of about 50% of comparison population levels by
the 6th week after exposure. Slow recovery ensued, but at 6 months they werestill slightly below -
the unexposed levels. However, by 1 year post exposure they had returnedto the level of the comparison population and have remainedso, with
the possible exception of those of children <12
years old, which generally have been lower than
those of the unexposed children of comparable
age.
Platelets fell to about 30% of the unexposed
values by the 4th week. By 6 months they had
reached 70% of the controls; at 1 year the mean
platelet count wasstill below that of the control
population but higher than at the 6-month survey.
Although further increases were apparent at the
2-, 3-, and 4-year examinations, the levels were
still below those of the comparison population.
Changes in hematocrit were not remarkable in
any of the groups.
Clinical examinations revealed no disease processes or symptoms which could beattributed to
radiation effects, aside from skin lesions, loss of
hair, and early symptoms. Epidemics of chicken
pox and measles occurred. The diseases encoun-
tered were no moresevere or frequentin the irradi-
ated group than in the unexposed group, even
during the period of greatest depression of peripheral blood elements. Three persons in the exposed
population died of disease: (1) a 46-year-old man
with a hypertensive heart disease which had been
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