BIOLOGY AND MEDICINE
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for the first year of reoccupation and will gradually decline thereafter. The Rongelapese who
go on fishing expeditions to other islands could be exposed to levels of radioactivity higher
than those of Rongelap; however, much of their time is spent on fishing boats over waters with
gamma activity near background values, Thus the external gamma radiation received by the
Rongelapese as a whole can be expected to be initially 0.5 roentgen or less per year.
There is no radiation standard which applies directly to the Rongelap situation. However,
standards established for normal atomic energy activities involving much larger numbers of
people may be of some significance in evaluating the Rongelap data. For occupational conditions, the National Committee on Radiation Protection and Measurement recommends that
adult workers not be exposed to more than 0.8 rem (roentgen equivalent for man) of whole body
radiation per week, or a 13-week dose of 3 rems when the weekly limit is exceeded. This
standard is further restricted by an age qualification, which provides that the maximum permissible accumulated dose in rems, at any age, is equal to five times the number of years
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beyond age 18, provided no annual increment exceeds 15 rems. Thus, for persons over 18
years of age the accumulated maximum permissible dosage is 5(N-18) rems, where N is the
age. This standard applies to all critical organs except the skin, for which the value is double.
For a large population, in contrast with the small group of Rongelapese, the maximum permissible exposure is an average of 14 million rems per million persons during the period
from conception up to the age of 30, and one-third of that amount in each decade thereafter.
Food Supply and Body Content of Strontium 90
Strontium 90 is the radioactive isotope of principal concern in the food chain of the
Marshallese. Analysis of the results from all the Pacific Islands surveyed shows a decline of
strontium 90 with the passage of time, except in the land crabs. Additional collections of land
crabs will be made on Rongelap to establish the reason for the increase in strontium 90 ac-
tivity.
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Maximumpermissible exposure to strontium 90 for the general population, in terms of
maintained level in the body, is 100 Sunshine Units (100 micromicrocuries of strontium 90
per gram of calcium). Exposure of the Rongelapese can be reduced by eliminating land crabs
from the diet and by reducing the consumption of such native plants as pandanus. Because
only a part of the strontium 90 will go from food to bone, these measures may limit the ultimate body burden for the Rongelapese to substantially less than 100 Sunshine Units.
Swine, chickens, ducks, and rats have continued to live on Rongelap during the period of
highest strontium 90 contamination in the soil-plant-animal cycle. Examinations of rats collected and sacrificed two years after the initial fallout show no gross or pathological changes
that could definitely be ascribed to radiation.
Medical Surveillance
When the Rongelap people are returned to their home island, they will be given regular
monthly medical examinations by local health personnel and an annual examination by a
physician from the United States. A dispensary will be maintained for regular health services.
Any unusual body accumulation of strontium 90 will be detected before harmful effects result.
Biological Surveys
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A summary report of the several biological surveys made of the Marshall Islands is being
prepared by the AEC staff. The basic studies were made by the University of Washington, the
Naval Radiological Defense Laboratory, and the New York Health and Safety Laboratory.
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DOE ARCHIVES
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