CHAPTER 4
HEMATOLOGY
4.1
PREVIOUS FINDINGS
Hematological determinations employed in the initial post-exposure period included total
leukocyte, neutrophile, lymphocyte, and platelet counts and hematocrit determinations. Whenever possible, an entire exposure group was studied in a single day. In order to estimate the
severity of the hematological response, findings were comparable to a phase of a control group
similar, where possible, with respect to race, age, sex, background, and habits.
Depression of the total white, neutrophile, lymphocyte, and platelet counts was marked in
the Rongelap group and less severe in the Ai&nginae group. The total white count was consistently lowest during the sixth and seventh post-exposure weeks, followed by an upward trend
with levels remaining below that of the control population at the end of the observation period.
The drop in lymphocytes was early and profound, with little or no evidence of recovery during
the period of observation. Fluctuations in the total white count were due to changes in the neutrophile count. Neutrophile counts in 10 per cent of the Rongelap group fell to below 1000
cells/mmat the time of maximum depression. Platelet counts showedless fluctuation than
did the total white and neutrophile counts and reached lowest values on the 30th post-irradiation
day. At this time, counts in 20 per cent of the Rongelap group were below 90,000/mm*. A
secondary fall in platelets, with greatest depression on the 55th day, was observed, and recovery to control levels was not complete at 6 months.
4.2
METHODS
Determinations made on peripheral blood included total white, neutrophile, lymphocyte,
and platelet counts, as well as hematocrit determinations. Techniques employed were identical
with those used during the initial observation period.’ Two determinations were made on each
individual approximately one week apart (date of all counts taken as the 185th post-irradiation
day). In addition to peripheral blood, bone marrow from the anterior or posterior iliac crest
was obtained on 21 exposed and 20 control individuals. Approximately 1 ml was aspirated, and
cover slip preparations were made from the small particles of marrow thus obtained. Differential counts were taken on these preparations. Part of the marrow was allowed to clot on a
glass slide and was then fixed in formalin-sublimate solution for later examination of histological structure and degree of cellularity.
4.3
PRESENT FINDINGS
Peripheral blood count data for the exposed and control populations are given in Tables
4.1 to 4.3, Figs. 4.1 to 4.4, and in Appendices A and B. To obtain valid comparisons within
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