2
part of the control group used for the growth and
development studies of the exposed children.
The accumulation of data from these surveysis
becoming increasingly voluminous. Since conditions 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.
Summary of Past Findings
Reports have been published on the findings of
surveys made at the following times after exposure: initial examination,: 6 months,” 1 year,’ 2
years,‘ 3 years,® 4 years,* 5 and 6 years,’ and 7
years.® The followingis a brief summary ofthe find-
ings previously reported.
Duringthefirst 24 to 48 hr after exposure, about
24 of the Rongelap people experienced anorexia
and nausea. A few vomited and had diarrhea.
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 2 weeks after
the accident, when cutaneous lesions and loss of
hair developed, due largely to beta irradiation of
the skin. It was apparent when the people werefirst
examined, a few days after exposure, that the
lymphocytes were considerably depressed and that
significant doses of radiation had probably been
received. In addition to the whole-body dose of
radiation and the beta irradiation of the skin, radio-
chemical analyses of the urine showed that measurable amounts of radioactive material had also
been absorbed internally. The effects of the radia-
tion can best be summarized under three headings
according to the mode of exposure: penetrating irradiation, skin irradiation, and internal irradiation.
PENETRATING RADIATION
One of the earliest findings indicative of significant exposure in these people was loweringoflevels
of leukocytes and platelets of the peripheral blood.
This was most marked in the 64 people on Ronge-
lap who had received 175 r, and was less marked
in the other groups receiving less exposure. The
hemopoietic depression was roughly proportional
to the dose of radiation received. Even in the 157
Utirik people who received only an estimated 14 r,
it was possible to distinguish slight platelet depression in the group as a whole. The smaller group on
Ailingnae and Rongerik showed peripheral blood
levels between those of the high and low exposure
groups. The chronological records of blood findings in the Rongelap and Ailingnae groups are pre-
sented in Table 10 and in Appendices 1 and 2.
Lymphopenia of abouthalf the level of the comparison Marshallese population was evident when
the Rongelap people were first examined on their
arrival at Kwajalein 3 days after exposure. This
depressed level was maintained steadily with only
slight increase noted by one year. In the following
year, mean counts approached the levels of the
comparison population but have since generally
remainedslightly below.
Neutrophil levels fluctuated considerably during
the first month; possibly this was related to the
prevalence of beta burns of the skin during that
period. Neutrophil depression became evident by
5 and 6 weeks post exposure with levels reaching
about half that of the comparison population. This
degree of neutropenia was insufficient to result in
any apparent increased infectious processes, and
indeed it was noted that neutrophilic leukocytosis
was possible in people showing casual infections
at this time. Neutrophil levels recovered more
rapidly than lymphocyte levels and reached near
control levels by one year. Subsequent annua! surveys have revealed that recovery does not appear
to be complete, particularly in younger and older
age groups.
Platelet counts showedless fluctuation than other
blood counts and fairly consistently showed increasing depression, reaching levels of about 30%
that of the comparison population by the 4th week.
A spurt of recovery to about 75% of comparison
levels occurred during the following few weeks,
which was followed by slower recovery but with
mean levels never reaching higher than 85 to 90%
that of the comparison population during the 7
years post exposure.
Erythropoietic depression has not been a consistent finding as with the leukocytes and thrombocytes. Slight depression of red blood counts, hematocrits, and hemoglobin have been noted at times.