were still below control levels, but by one year
post-exposure they had returnedto the level of the
comparison population.
Platelets fell to about 30% of the control values
by the fourth week. By six months they had
reached 70% of the controls; at one year the mean
platelet count wasstill below that of the control
population but slightly higher than at the sixmonth survey. At two years the platelets, though
still slightly below the control level, showed some
further increase over the one-yearlevel.
The depression of blood elements in the Ailingnae group who received an estimated dose of 69 r
was similar to that in the other group except that
it was less marked. Even though the doseofirradiation received by the Utirik people was quite
low (about 14 r), a slight depression of platelets
wasobserved duringthefirst month post-exposure.

Changes in the hematocrit were not remarkable

in any of these groups.
Clinical observations revealed no disease processes
or symptoms which could be attributed to radia-

tion effects aside from skin lesions, loss of hair, and

early symptoms. The diseases encountered were
no moresevere or frequentin the irradiated than
in the nonirradiated population even during the
period of greatest depression of the peripheral
blood elements. Up until the two-year examination no deaths had occurred amongtheirradiated
people. It was difficult to evaluate the effects on
fertility; however, a number of apparently normal
babies were born and further pregnancies occurred. No opacities of the lens or other eye
changes were found that could be attributed to
irradiation. The height and weightof the irradiated children wereslightly less than those of the
unirradiated children of the same age, but because

of the small numbers of children involved, no

definite statement could be made.
Beta Irradiation of the Skin

No accurate estimate of the radiation dose to
the skin could be made. Lesionsof the skin and
epilation appeared about two weeks after exposure, largely on parts of the body not covered
by clothing. Most of the lesions were superficial;
they exhibited pigmentation and dry, scaly desquamation and were associated with little pain.
Rapid healing and repigmentation followed.
Some lesions were deeper, exhibited wet desquamation, and were more painful; a few became

secondarily infected. Repigmentation gradually
took place in most instances, and someofthe healing lesions, particularly on the back of the neck,
developed hyperpigmentation ofa grayish, dusky
color and a thickening of the skin with “orangepeel” appearance. At one year, however, this type
of pigmentation was greatly reduced. Deeper
lesions on the dorsum of the feet continued to
show lack of repigmentation, with scarring in
some cases. At two years post-exposure 15 cases

continued to show residual skin effects largely in
the form of pigment aberrations, and someatrophy andscarring. Histopathologicalstudies of the
skin showed changes consistent with radiation
damage. A commonfindingin acute lesions was
spotty transepidermal damage accompanied by
atrophy and flattening of the rete pegs with areas
of relatively normal skin between. The dermis
was muchless affected than the epidermis. Biopsies taken on later surveys showed considerable
improvement but with somepersisting changes.*
In no case was there evidence of any premalignant
or malignant change.
Pigmentation of the semilunararea ofthefingernails and toenails was observed in about 90%
of the people about three weeks after exposure. By
six months pigmentation had largely grown out
with the nail and had disappeared in mostcases.
Internal Irradiation

Radiochemical analysis of numerous urine
samples of the exposed personnel showed some
degree of internal absorption of radioactive materials, probably brought about through eating and
drinking contaminated food and water. Calculations of the body burden of these materials, however, showed that the concentration was too low

to result in any serious effect. Analysis of urine

samples six months after exposure showed only

barely detectable radioactivity present in some
cases. At two years radiochemical examination
of pooled urine samples showed Sr°°=0.6 and
Ce’*4-Pr'** =7.0 disintegrations per minute per
24-hr sample. (The samples were not analyzed
*In somesections acanthosis, absence of pigment in the basal
layer, and atrophy and benign dyskeratosis were noted in the

stratum spinosum of the epidermis. Changes noted occasionally
in the dermis consisted of areas of homogenization and increased

density of collagen, alteration in the distribution of mucopolysaccharide, presence of mucin in areas of degeneration, and capillary dilatation.

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