46
EFFECTS OF IONIZING RADIATION
were sufficient in number to allow all samples
to be taken in rapid succession, and timeintervals were rigidly controlled.
4.2
Methods of Treating Data,
' Control Groups
Pre-Exposurs Bioop counts were not available
on the exposed Marshallese or Americans:
hence the individuals could not be used as their
own controls. In order to estimate the severity
of the hematologic response it was necessary to
establish control groups as comparable as pos-
from Group .A and two from control Gro
were omitted on this basis.
{In the following descriptions and com
sons of the data, findings in the exposed gi
are frequently expressed in terms of perce
the appropriate age and sex control grou]
should be noted, however, that in observat
studies of this kind, unknown factors |
poaxthly account far part of the differences:
between the control and exposure groups
thaugh all possible measures were taken |
lect comparable control groups. In additi
was not possible to obtain more than a s
blead sample on each control individual.
these reasons, statistical tests of signifi
sible with respect to age, race, sex, background
and habits. A control group of 115 Marshallese from Majuro atoll (Control Group .A),
comparable with respect to age and sex to exposure Group I was obtained during theinitial
observation period.* For comparison with the
exposed Americans, blood counts were done on
approximately 85 American men on duty at
Kwajalein. All who had not been on duty in
the tropics for more than 2 months were excluded, since the exposed Americans had been
tical tests for whichit is not necessary to sp
the functional distribution of the variate 1
study) were used (2-7). The advantag
nonparametric methods have been summa
by Moses (8).
associated with radioactive materials were ex-
4.3
used as the Kwaj-American control group.
Data from the control group A were examinedto determine the age and sex dependency
In Taste 4.1 are shown for control group .
To obtain valid comparisons within and among
the various exposure groups, the age and sex
dependencies noted for the control groups were
taken.into account. Although each individual
in all groups was studied hematologically, those
Marshallese with serious long-standing diseases
were omitted from the analysis. .\ total of two
breakdown used for comparisons among
posure groups is shown in Table 4.2. In
breakdownthe age and sex dependencies 1
for the Marshallese control groups were t
into account insofar as was practicable
should be neted that the Group B control v
(Table 4.1) agreed closely with the Gro
control data, To allow additional compa
in the aren for that period of time before exposure. In addition, several who were recently
cluded. Theresulting smaller group of 67 was
of the several hematological determinations.
*A second control group of 82 Marshallese from
Majuro atoll (control Group B) were obtained during
the 6 month medical resurvey.
While data from these
individuals are given in this report, they are not used
for comparisons because of a measles epidemic during
the resurvey,
were applied mainly to time changes with
exposure group, and not to «differences bet
control and exposure groups. For the pu
of detecting significant changes in the her
logical pattern, nonparametric tests (1. e.,5
Hematological Findings, Gen
age and sex, the mean values for the total y
neutrophile, lymphocyte and platelet coun
well as for the hematocrit.
The age anc
between effects on children and adults, the
trophile counts were arbitrarily separated
the age groups used for the lymphocyte co
Monocytes and eosinophiles were broken +
also into the same age groups. The age