36
However, since the latter children were on the average 4 months older, the data did not justify a
conclusion that the difference in stature was associated with the exposure of the parents.
Residual beta burns of the skin consisting of
varied degrees of atrophy, scarring, pigment aberrations, and hyperkeratosis were noted as in past
surveys in about 10 people. During the past several
years an increase in the number of pigmented
nevus-like lesions has been noted in areas previously involved with beta burns. These appear to
be increasingslightly in number. Histological diagnosis of one such lesion that was biopsied indicated that it was a typical pigmented nevus. No
case of chronic radiation dermatitis or malignant
change in the residual burns was noted.
Genetic studies have not been specifically conducted in view of the small population involved
and the generally negative results of the studies on
first-generation Japanese children of exposed parents. However, routine examination has revealed
little in the way of congenital anomalies in the
children of exposed parents. One baby born of an
exposed mother in 1960 was diagnosed as having
congenital heart disease and died several months
after birth. The suggested evidence of increased
miscarriages andstillbirths in the exposed woman
during the first several years after exposure might
be related to irradiation of the germ plasm,al-
though this tendency was not apparent in recent
years.
Hematological studies showed mean leukocyte
levels lower this year than last year in both exposed and unexposed groups, but the exposed
group continued to show lower neutrophil and
lymphocyte levels than the unexposed group.
Platelet levels were higher this year in both groups
than previously, but the exposed group continued
to show slightly lower levels. There was an increase in erythrocytes in both exposed and unexposed groups, with little difference noted between
the groups. The deficit in leukocytes and platelets
in the exposed people was more apparent in the
younger and older groups than in the middle
group. Bone marrow examinations showed a reduced myeloid-erythroid ratio in 8 of 9 cases with
abnormalities of the erythroid and myeloid precursors in some. In view of these findings, it is believed that there is some residual effect of radiation
exposure on hematopoiesis in these people.
Peripheral blood cultures or chromosome
studies were carried out on samples from a number
of people. Successful cultures were obtained in
some 40 of 70 bloods; however, difficulties were
encountered under field conditions of high temperature and humidity in obtaining satisfactory
chromosome smears. Nevertheless small numbers
of dicentrics along with abnormal diploid numbers
were noted in a few smears. These data suggest
that resistant damage to blood cells occurred, and
during the next survey further chromosomestudies
of blood and skin of beta burned areas and possibly of bone marrows are being planned.
Gammaspectrographic analyses were not carried out this year since previous levels of g -na
emitting isotopes (Cs?*? and Zn**) had not
n
significant further increase at the time of the
71
survey. However, urinary excretion of Sr*° was determined by radiochemical analysis on 24-hr samples from 18 exposed and 9 unexposed people. As
previously noted, there were no differences between the exposed and the unexposed urinary
levels of Sr*. The mean level of Sr was 114 +14
pC/g Ca. On the basis of previous calculations, the
estimated body burden of Sr*® was 12.0 muC,
which is about 6% of the MPC (200 niyC for non-
industrial populations). Several bone samples obtained from autopsy on the 78-yr-old exposed
woman showed an average of 15 pC/g Ca, representing a body burden of 11.4 muC or about 5.7%
of the MPC, which compares favorably with the
estimate based on urinary excretion. These levels
represent about a sixfold increase in Sr°° over the
1958 levels. Analysis of 4 coconut crabs from the
Island showed high levels with little reduction
during the past few years, necessitating a continuation of the ban on eating these crabs.
Although the acute effects of radiation exposure
in the Marshallese have largely subsided, it is possible that certain late or delayed effects may occur.
Somelate effects have already been observed in
the Japanese, such as an increased incidence of
leukemia and possibly other malignancies and also
development of cataracts. Still other late effects
have been observed in irradiated animals. It is
unlikely that such abnormalities will develop in the
relatively small Rongelap population, and, should
they develop, the incidence should be quite low.
Nevertheless, it is extremely important that further
surveys be conducted to detect subtle changes associated with the development of such abnormualities so that they can be documented and therapeutic