HEMATOLOGIC OBSERVATIONS
sure severity except when counts on groups to be
compared are performed at the same time.
The platelet count showed a more systematic
trend than did the neutrophile count. Differences between the low-dose Group IV and
controls at the time of maximumdepression for
all groups with the exception of adult males
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Fictre 4.11.—Cumntative platetet counts for Groups
I (Rongelap), (7 (Ailinginae), and IV (Utinik) and
control Group A at the time of marinuum depression,
TIME OF26
PEAK
DEPRESSION _POST
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Fictre 4.12.—Caumiutaticve platelet counts for Group I
(Rougelap) at the time of mearinuon depression and
G months after erposurc.
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could be noted, and detectable differences existed
between the means for the Marshallese higher
exposure groups. Platelet counting is as easy
as, and more reproducible than leukocyte counts
1.21). Thus, the platelet count may prove to
bea useful index of degree of exposure throughout a large part of the sublethal range.
The above considerations are in accord with
previous findings on humanbeingsand animals.
4.5
61
Conclusions
1. Consiprration Or Tre degree of depression of peripheral cellular elements indicates
that exposure of Group I was moderately
severe, probably within 50 to 100 r of the level
where some fatalities would have resulted.
2. The degree of etfect evidenced in Group I
people is not inconsistent with the physical
estimates of gamma dose received, when the
geometry of exposure and other factors are
considered. Beta lesions of the skin, and the
low levels of internal radioactive contamination observed are considered not to have contributed significantly to the hematological
changes seen.
3. The extensive serial hematological data
obtained, considered in connection with previous data, allow reasonably accurate characterization of the hematological response of human
beings exposed to single doses of penetrating
‘adiation in the high sublethal range. The
pattern of change of some elements may be
different for higher dose levels; (see earlier
discussion).
The time course of events is different from
that observed in large animals and maybe described as follows
a) The total white count increases during
the first 2 or more days andthen decreases below
normal levels. The total count. then fluctuates
over the next 5 or 6 weeks, with no definite
minimum and with some values above normal
(the presence of thermal or beta lesions, or
other acute processes during this time mayaccount in part for these fluctuations). The
count becomes stabilized during the 7th or 8th
weeks at low levels, and minimumcounts probably occur at this time. A definite trend upward is apparent in the 9th or 10th weeks;
however complete recovery may require several
months or more.
b) The neutrophile count parallels the total
white blood cell count. Complete return to
normal values does not occurfor several months