(=
3.
4
The hematological surveys continue to show considerable fluctuation in
the year-to-year mean levels of leukocytes in both the exposed and
unexposed groups. ‘The mean leukocyte level of the exposed group showed
a decrease at the 1960 survey compared to 1959 (no unexposed people were
examined).
The reasons for these fluctuations are not apparent.
At
five years post-exposure (1959), the exposed peoplestill had mean
platelet levels 10 to 15% below those of the unexposed group, but in
1960 the lymphocyte levels for the first time equaled those of the
unexposed group. The mean erythrocyte levels were slightly lower in
the exposed people but a general anemic tendency exists in all
Marshallese, both exposed and unexposed.
The fact that some of the
blood elexents in the exposed group have not yet returned to the
levels of the unexposed group raises the possibility that a residual
radiation effect on the bone marrow persists, but other, not immediately
apparent, factors may be involved.
Radionuclide body burdens of C5137, 75 and Sr99 were evaluated by
measurement in e whole-body counter or by estimation from radiochemical
analyses of the urine.
The mean body burdens for 1959 were:
Cs137 =
0.57 4c; 265 = O.bhec; and S190 = 6.04c. The body burdens of 705
and Sr?0 continue to rise but at decreasing rates, whereas the level for
Csi37 appears to have reached equilibrium and now to be diminishing.
—'
Little or none of the body burdens of the exposed group appear to be
due to the initial exposure, since at present there is little difference
between the levels of the exposed and unexposed populations living on
Rongelap Island. This may be explained by the fact that additional
weapon tests held in the area have deposited additional fission
products into the enviroment, and the fact that certain staples of
diet are imported and, hence, the people are not living in a "closed
environment."
Consequently, it may never be possible to equate body
burdens with enviromental contaminations.
In any case, the body
burdens are now and will be of small significance interms of rediation
hazards.
Judging from the Japanese populations being studied by the Atomic Bomb
Casualty Commission at Hiroshima and Nagasaki, the next five years will
be the critical period for the development of leukemia in the
Mershallese.
Since animal experiments indicate that still other late
effects may occur in man such as premature ageing, shortening of life
span, increase in degenerative diseases, genetic changes, etc.,
continued careful examination of these populations is in order; all
effects should be documented and therapeutic procedures instituted
wherever possible, should such effects develop. In addition, the
relation of the environmental contamination on Rongelap to the body
burdens of radionuclides of the people living there, imperfect though
it is, warrants close study.
The United Nations Scientific Committes on the Effects of Atomic
Radiations now reviews these yearly surveys.