heel or ear.

Subsequently, venipuncture specimens anticoagulated with heparin

were used. Since 1973, NajEDTA has been used as the anticoagulant. Duplicate
pipettes were filled for leukocyte and platelet counts and diluted with 3% acetic acid or 1% ammonium oxalate, respectively, and each was then dispensed
into a single hemocytometer chamber after 10-minute rotations and counted by

phase microscopy after settling 10 minutes.

Hematocrits were measured in

heparinized capillary tubes.
One-hundred-cell differential counts were performed on Wright's stained blood smear and used to calculate absolute concentrations of leukocyte subsets.
Hemoglobin concentration after conversion to
cyanmethemoglobin was measured with a Lumitron colorimeter.
Hemocytometrics were used for leukocyte counts until the introduction of
a Coulter counter during the third annual survey (1957).
Erythrocyte counts
were also performed with the Coulter instrument, and modifications in orifice
diameter allowed electronic counts to replace phase microscopy for platelets
after the fourteenth annual survey.
The Coulter counters were superseded in
1973 by instruments

from General Science

platelet (MK-4) enumeration.

for both

leukocyte

(MK-3)

and

In 1978, a J.T. Baker Instruments (Milford, CT)

MK-4/HC platelet counting system was adopted, along with a Baker MK-40 fourparameter cell counter to measure leukocytes, erythrocytes, hemoglobin, and
hematocrit.

Initially, hematologic measurements in exposed individuals were repeated

in duplicate or triplicate at weekly intervals.
By 1962, a repeat determination was made only if an abnormal value was observed.

C.

Results and Discussion
Specific mean hematologic values over the last five-year survey period

are presented in Figures 2 to 4, segregated on the basis of exposure group and
sex.

It should be emphasized that the values for the Ailingnae group repre-

sent means of only 4 to 8 determinations (Table 1), and this clearly contributes to their variability. No statistically significant differences were de-

monstrable among the three groups exposed to radiation and their appropriate
comparison populations for any of the mean hematologic values recorded during
this period.
Certain measurements showed tendencies to segregate on the basis
of sex, however, regardless of exposure group.
These included increased
platelet counts in females (Figure 4) and the expected increases in various

red cell parameters in males (Figure 3).

Variation between sexes in platelet

concentrations has been observed consistently throughout the 26-year study pe-

riod and appears to represent a true anthropometric distinction in the
Marshallese, as it does in Caucasians. The sporadic very low values for individual platelet counts shown in Figure 7 most likely represent technical
artifacts.

Despite the lack of significant variance among group means, a number of

individuals exhibited sufficient deviations in certain hematologic measurements to require followup assessments.
Figures 5 to 7 record individual
values segregated by exposure group, sex, and time of study between 1975 and

1979 for persons whose hemograms contained values outside the ranges 4,280 to

10,640/y1 Leukocytes, 10.2 to 17.2 g/dl hemoglobin, and 120,000 to 372,000/y1
platelets.
These ranges represent values more than one standard deviation

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