represent the only barge series tn which systematiesserial Counts Othe sae pclividundls dave
heen possible, and thus they comprise the most complete data available on human Deri Ox
posed in the high sublethal range.
Tt is also of dimportiance, therefore, to examine the presen
4.13.2
Me?
results bi conjunction with past experience inian effort to gainoa better understanding of (he
hematological response of human berms exposed fo penetrating tadbitron ti Che subleduadl range.
In the following discussion it will be generally assumed that the hennuitological effects
noted were due primarily to the penetrating pam radiation received. The beta radiation injury of the skin may have contributed to fluctuations in the white count during the period of
aclive lesions during-the third, fourth, and fifth week, bul is considered not to have contributed
significantly to depression of any peripheral clements (see chapter 3). The degree of internal
contamination with fission products (see chapter 5) was probably too small to contribute significantly to the carly hematological effects observed. Although it is not possible to say with
certainty that these added factors did not materially affect the hematological pattern seen, it
will become evident in the discussion that the changes observed are not inconsistent with those
to be expected from exposure to penetrating radiation alone. Thus the hematological changes
noled are considered to be the result of a single exposure to penetrating ganima radiation, delivered at rapidly decreasing dose rates over a period of approxtmately two days. Unless
otherwise stated af] discussion wilt be limited to the adult Rongelap group.
The principle sources of previous data availiable for comparison, and the characteristics
and limitations of cach are summarized in Table 4.10. Perusal of the table will make apparent
the difficulties involved in attempting strict comparisons; however, some statements can be
made despite the obvious limitations. For easy reference, “normal” values for peripheral
blood counts, from the present data and from the literature are presented in Table 4.11.
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Comparison with the Japanese Data
The limitations staced in Table 4.10 apply to the Japanese low dose groups* E to H in par-
licular, in which values given*®:"’ are pooled and include individuals located at the time of the
bombing such that they may not have received significant exposure, Hence, while the pattern of
change with respect to time is of value, absolute counts probably are high. The time course of
hematological change i: the Rongelap people corresponded most closely witk these low exposure Japanese groups in which definite signs of severe radiation exposure were present in
wae eee nen f
some individuals but in which essentially no mortality occurred (inittal hemotological studies
on the Japanese terminated at 15 weeks). The early period up to approximately six weeks was
characterized by cunsiderable variation in total white count in both the Rongelap and J: ~anese
people. This fluctuation may be associated with the presence of thermal or other injur. 3; in
the Japanese or the active skin lesions in the Marshallese, or may correspond to the ‘abortive
rise" noted for animals following exposure."'"™ From the sixth week until the termination of
the acute studies on the Marshallese during the tenth week, the Japanese and Marshallese
counts remained at similar levels.
.
The neutrophite count in both the Japanese and Marshallese in general paralleled the total
white count. The lymphocyte count in both groups was depressed carly and remained depressed
at values of approximately 2000 until week 10. The high value of 2692 reported for the Japanese
for weeks 12 to 15 must be suspected of being high for the reasons given in secthon 4.13.2.
Three characteristics of the Japanese hematological trends should be pointed out: a) while
high dose exposure groups with significant mortallly showed early depression with a definite
low point at four weeks, the lower dose groups showed no definite minimumal four weeks but
rather a continued depression until the eighth or ninth weeks. b) While the mean values for
total white and neutrophile counts for even the heavily exposed groups had rcturned to within
*The Japanese casualties were divided into groups A to H on the basis of degree of exposure as determined roughly by distance from the hypocenter and approximate degree of shielding. In groups E to H essentially no mortality ascribable to radiation exposure occurred in the
{first 3 or 4 months.
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