LYMPHOCYTES 107

a

CONTROLS GROUP A -AGE <5

AGE<5 (13)

o

8

‘6°

24

32
40
POST EXPOSURE DAY

56

185

Figure 4.2.—Serial changes in lymphocyte count of

Group I (Rongelap) for those less than 5 years

and greater than 5 years of age.

Qa

CONTROLS GROUP A-LEUKOCYTES
GROUP I

o

~t

and

a

LEUKOCYTES
AGE > 5(49)
GROUP A-NEUTRO-

| PHILES

rt

|

ui

Il

nN

reached. The count was maintained at approximately 75 percent of control values from
the 7th week to the end of the initial study.
No further recovery was evident at 6 months.
Although both age groups followed the same
general time pattern of response, the lower age
group was below that of the older throughout
most of the observation period. At 12 months
the granulocytes had returned to the control
range.
The absolute lymphocyte count of the older
age group (Fig. 4.2) had fallen by the 3d day
to a value approximately 55 percent of the
control group. This value was maintained
throughout the study, and there was no definite
evidence of an upwardtrend during the initial
or 6 month studies. At 12 months, complete
recovery had not occurred. The values for the
younger age group likewise fell before the 3d
day toa value approximately 25 percent of the
control, following which there wasa significant
upward trend. With the total lymphocyte
count, there is a consistent difference between
the two age groups. However, duringthefirst
+ weeks the difference is accentuated when expressed as percent decrease because of the relatively high lymphocyte levels in the lower age
control group. After this period the differences
expressed as percent are less marked since re-

5

EFFECTS OF IONIZING RADIATION

LEUKOCYTES, NEUTROPHILES AND LYMPHOCYTES x 10?

48

|

-

ot

at

NELITROPHIES
AGE>Sia9o}
|

LYMPHOCYTES"
AGE > 5(49)

POST EXPOSURE DAY
FIGURE 4.3.—Comparative serial changes in the total
leukocyte, neutrophile, and lymphocyte counts tn
those greater than 2 years old, Group T (Rongelap).

covery was more rapid in the younger age
group.

The cellular elements chiefly responsible for

the fluctuations in total white blood cell count
can be determined by comparingthe total white,
neutrophile and lymphocyte counts (Fig. 4.3).
It is seen that the lymphocyte count remained
essentially constant throughout the period of
study, while the total neutrophile count fluctuated with a pattern essentially identical to that
of the total] white blood count (coefficient of
correlation of 0.9). Thus the fluctuations in
total count were due to changes in the neutrophile count. This was true of both the older
and younger age groups. It can be seen from
Table 4.2 that the neutrophile count was consistently greater than the lymphocyte count in
the older age group. In the younger groups,
differences in the neutrophile and lymphocyte
count were less marked and frequently the
lymphocyte count was greater than the neutrophile count.
Platelets were first counted 10 days after exposure, at which time platelet values of the
females were approximately 60 percent of the
appropriate control group (Fig. 4.4). Follow-

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