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ENERGY Mev
Figure 17. Net in oivo gamma-ray spectra of Marshallese.
acute or subacute effects andlate or long-term
effects. The discussion will concern largely the 64
Rongelap people whoreceived the highest dose
(175 r) of whole-body radiation.
ACUTE AND SUBACUTE EFFECTS
Penetrating Radiation
Symptoms. The only symptomatological evidence
of acute effect from the penetrating radiation was
the occurrence of anorexia and: nausea, and ina
few individuals vomiting and diarrhea, during the
first two days after exposure. That these symptoms were unequivocally related to radiation is
validated by the fact that they did not occur in the
groupsreceiving lower exposure. Other than these
early ones, however, during the three years of ex-
aminations there have been no symptoms that appeared to berelated to radiation effects, except
those associated with superficial irradiation to the
skin.
Hematological effects. The early significantreduction of lymphocytes followed by depression of
other leukocytes and platelets indicated that
serious radiation exposure had occurred. Only a
slight effect on erythropoiesis was observed in the
form ofa slight drop in the hematocrit levels during the first 6 to 8 weeks. The degree of the
hematopoietic depression was consistent with the
calculated dose of 175 r whole-body penetrating
radiation.
Determination of degree of hematopoieticrecovery during the past two years has been increasingly difficult because of problemsin selec-
tion of unexposed “control” populationsas outlined earlier; apparent changes in blood levels
from year to year in different control groups; and
closer proximity of the blood levels in the exposed
groups to those in the unexposed population. The
general lowering of leukocytes in the exposed
group this year would be disturbing exceptthat
the unexposed group also showedsimilar lower
counts when comparedwith the control population used last year. One must consider the possibility that a downward trend in the white blood
cell level of the whole population may be occurring such as has been reported in the Japanese
people over the past 10 years." If this is true in
the case of the Marshallese, it would not seem that
such a trend had affected the more isolated Utirik
people, whose blood levels were more comparable
with those of last year’s controls (Rita or 8,).
Determination of white blood cell levels of these
groups at the next annual medical survey at four
years post-exposure will no doubthelp clarify this
issue.
It seemslikely that a slight lag in recovery of
lymphocytes and platelets does persist three years
post-exposure whenvalues for these elements are
compared with the unexposed group levels. In
contrast to the leukocytes, the platelets showed a
slight increase over last year’s values. Negative
results in bone marrow examinations (carried out
at 6 months and during this survey) do not
negate the possibility of a slight degree of impairmentof hematopoiesis, since a slight depression of
elements noted would notbelikely to be detectable in the bone marrow examinations.
The lowerlevels of hematocrits appearto parallel the reduction of leukocytes, and an explanation based on decreased ervthrocyte production as
a radiation effect does not seem likely, since eryth-
ropoietic depression was not a prominentfeature
of the radiation effects and hematocrits arealso
low in the unirradiated population. Theslight
anemic tendency may possibly be related to blood
loss associated with chronic parasitic infestation
and other formsof chronic infection. Nutritional
deficiency such as iron deficiency, low dietary protein, or interference with absorption of vitamin B,,
are possibilities, but there is no good evidence that
these factors are involved. They will, however, be
given careful consideration in the next survey.
Response to infection. The Marshallese experience
has madeit clear that nature has endowed human