73
probably with less internal absorption of radionu-
clides, since their stored water and food were cov-
ered, and they have had nothyroid effects (see
Appendix 2).
Evaluation of the effects of radiation exposure
in humanbeings (patients, physicians using radiation, accident cases, etc.) is always difficult because
of uncertainties regarding exact dosage,fractionation and dose-rate effects, partial-body exposure,
complicating diseases, etc. The doses received by
the Marshallese, like most human exposures,
could be only roughly estimated, although the
hematological data were compatible with thecalculated whole-body doses. Even greater uncertainties were encounteredin estimating the doses due
to internal absorption of radionuclides.
The data on the effects of fallout radiation in
the Marshallese have provided important information that will apply in a general way to any
population exposed acutely to fallout. However,
the effects may be modified in othersituationsif
nuclear explosions occur in regions with different
terrain, soil types, climate, and availability of protective measures.
C. ACUTE EFFECTS
The most serious acute effects of the exposure
in the Marshallese were due to penetrating gam-
ma radiation. These included transient anorexia,
nausea, and vomiting andsignificant depression of
the peripheral blood elements in many members of
the higher exposure Rongelap group. The hematological depression was not sufficient to produce definite clinical signs and required no specific therapy.
Contamination of the skin in the Rongelap
group resulted in wide-spread beta burns on parts
of the body not covered by clothing and in spotty
epilation of the scalp. These effects were probably
aggravated by delay in decontamination and by
perspiration due to the warm climate causing the
fallout to stick to the skin. The superficial nature
of the lesions, rapid healing with minimalresidual
skin changes, and regrowth of hair were no doubt
due to the low average energy of the beta radiation
in the fallout.
Thelack of recognizable acute effects from the
internal absorption of radionuclides is noteworthy
in view of the serious thyroid abnormalities that
later developed.
Because of residual contamination ontheislands,
radiological monitoring of personnel and environment has been an importantpart of the surveys in
evaluating body burdens of radionuclides in the
Rongelap and Utirik »eople. Recently the areas
undergoing such monitoring have includedBikini
Atoll and the people who have returned to live
there, and theywill also include Eniwetok when
its people return home.
D. LATE EFFECTS
The possible emergenceof late effects of exposure in the Marshallese has received considerable
attention in follow-up examinations. Exceptfor
the thyroid lesions and the one case of leukemia,
only a few findings possibly related to radiation
exposure have been seen; otherwise the general
incidenceofillnesses and the overall physical condition have been similar in the exposed andin the
unexposed comparison groups. The increase in
miscarriages andstillbirths among the exposed
Rongelap women duringthefirst 5 years after exposure may or may not have been related to radi-
ation effects. No genetic effects have been noted in
the children born of exposed parents; this is not
surprising in view of the generally negative findings in the much larger Japanese study. Thefindings of persistent chromosome aberrationsin cultured peripheral blood lymphocytes at 10 vears
post exposure and a possible somatic mutation in
hemoglobin in several of the exposed group suggest that genetic mutations mayalso be present.
The possibility of genetic effects in the offspring is
of serious concern to the exposed people and deserves further study.
Effects of radiation onlife shortening or mortal-
ity are difficult to evaluate because of the small
numberof people and the differences in age distribution between the exposed and comparison
groups. The only death that mayberelated to exposure is that from leukemia. The occurrenceof a
few additional cases of cancer (other than thyroid)
cannot be ascribed definitely to radiation exposure. The lack of skin cancer from beta burns may
be related to the minimal natureofthe residual
skin changes, probably dueto insufficient radiation injury to the dermis, but the possibility of skin
cancer developing must be kept in mind because
the latent period may be very long.
The developmentof a case of acute leukemia in
the Rongelap boy may or may notberelated to
radiation exposure. However, this disease appears
to be even rarer in the Marshall Islands than in
the U.S. It is noteworthy that his disease was the