29
city of vital statistics in the Marshallese and the
small numbers of people involved.
Nodiseases, infectious or noninfectious, have
developed which could be related directly to radiation effects. The incidenceof diseases in the exposed people noted during the 4-year survey, as in
previous surveys, remained about the same as
found in the unexposed comparison population.
A limited survey of immune responses of the exposed groupat 3 years post-exposure® showed that
the antibody response to tetanus antigenic stimulus was notsignificantly differentfrom the response
in the unexposed group.
Three deaths have occurred in the exposed
people. Thefirst was in a 46-yr-old man whodied
of hypertensive heart disease 1 year post-exposure.
He had had thedisease at the timeof irradiation.
The second occurred in a 78-yr-old man at 2 years
post-exposure. He was a diabetic of long standing
and died apparently of coronary heart disease. A
third occurred in April 1958, after the present
survey, in a 35-yr-old man from the groupthat
received 69 r, due to pneumonia complicating a
severe case of chickenpox. In noneofthese cases
was there any direct evidence that death was due
to radiation exposure.
Lag in recovery of some of the peripheral blood
elements of the exposed people over the 4-year
period since exposure is in sharp contrast to the
much morerapid recovery seen in animal studies,
but generally conformsto the recovery pattern
seen in the Japanese exposed at Hiroshima and
Nagasaki. In the Marshallese the myelocytic series
showed earliest recovery (by | year post-exposure),
with lymphocytes and platelets exhibiting much
slower recovery. The present hematological exam-
examined by comparing differences between the
mean peripheral blood elementlevels of this group
and the corresponding group of unexposed women
with differences between levels in exposed and un-
exposed menof the sameage group. Nosignificant
differences were seen.
It might be questioned whether or not the
present low body burden of radionuclides might
contribute to delayed recovery of hemopoietic
function. Admittedly little is known of possible
effects of such low level exposure on the marrow,
particularly if, as in the case of the Marshallese,
a significant dose of penetrating radiation has been
previously received. However,it is not believed
that the small amountof additional radiation imposed on the marrow from this source would be
sufficient to retard hemopoietic recovery.
Hematological examination at 3 years postexposure revealed a drop in the mean leukocyte
counts compared with 2-year levels in both the exposed and unexposed people. The possibility was
considered that a population trend downward in
leukocyte counts was occurring such as has been ©
seen in Japan.*’ However, this does not seem to be
the case, since leukocyte levels this year are not
further depressed compared with previous levels.
The acute effects of the beta irradiation of the
skin subsided rapidly, and only 12 cases still show
residual scarring and pigment abberation.It is
possible that the acute stage of the beta burns may
have caused some of the fluctuation observed in
the white blood cell count. In those showing
epilation, complete regrowth of hair occurred by
6 months post-exposure.
No acute effects of the internal absorption of
radionuclides were observed.
inations reveal that the meanleukocyte level has
virtually recovered to the control level, but more
individuals had lower counts than in the unexposed group. Thrombocyte productionstill does
not appear to have recovered completely as evidenced by the lower meanlevels in the exposed
people both individually and as a group. As has
seen, but certain of the more fundamental of these
peripheral blood level of these elements has not
impaired in any observable waytheir resistance to
disease.
The 3 deaths that have occurred in the exposed
population do not appearto indicate a higher
mortality rate than seen in the comparison popu-
whetherthereis a lowered reserve hemopoietic
capacity in the marrow of the exposed people. The
effect of the natural stresses of childbearing and
menstruation in women 15 to 45 years of age was
that someof the higher estimates oflife shortening
per roentgen may be too high.
Premature aging'®:*? is difficult to assess. From
observations over the past 4 years the impressionis
been pointed out, however, the slightly lower
There has been considerable speculationas to
LATE EFFECTS
Late effects of radiation exposure have not been
effects that have been observed in animals and to
a lesser extent in man will be mentionedin relation to the Marshallese.
Shortening oflife span**-*? has not been evident.
lations. From these observations it would appear