Early research on the subject was largely confined to short-lived
species of animals such as rats. and mice and to brief experiments of a
year or two at most. Considerable uncertainty exists, however, in extrapolating the results of these experiments when calculating the effect
of long-duration, low-intensity exposures on man.
These data must be
Internal emitters. Radioactivity accumulates in the human body
followin; prolonged exposure to certain radioactive isotopes in air,
water, or food, inasmuch as these isotopes are selectively absorbed by
various organs of the body. Depending upon the rates of absorption and
excretion, the energy of the radioactivity, and the sensitivity of the
organs to radiation damage, it is possible to arrive at a figure for the
permissible concentrations of the radioactive elements in air and water
consumed by human populations.
All the values of the biological reac-
tions required for the calculations (such as rate of absorption, sensitivity, etc.) are not known accurately, and the calculated results must
be qualified with arbitrary “safety factors" which may or may not be
fully justified. Research programs to obtain better data are in effect
at the Los Alamos Scientific Laboratory and at Argonne National Labora~
tory, and it is planned to encourage the initiation of research projects
in this field at other AEC facilities and at private institutions during
the next year.
Radiation Injury and Long-Term Effects
Radiation cataract studies.
The appearance of incipient cataracts
among a few nuclear physicists (off the nroject) who had been exposed to
cyclotron-produced radiation led to the Commission's request last year
that the Division of Medical Sciences of the National Research Council
make a thorough study of the problem. The Committee on Radiation Cataracts of the National Research Council, established for the purpose, assisted in studying the cases of radiation cataracts, recommended a sound
research program, and screened research proposals for their scientific
merit. As a result of their recommendations, approval was given during
the quarter to research projects on radiation cataracts at four universities - Harvard, Lassachusetts Institute of Technology, University of
Chicaso, and State University of Iowa. These are listed in further detail in Appendix D. Other proposals are under consideration, and related
studies are being made at Oak Ridge National Laboratory and Argonne na-
tional Laboratory.
At the suggestion of the Committee on Ophthalmology of the National
Research Council, the Atomic Bomb Casualty Commission (with funds pro-
vided by the U. S. Atomic Onergy Commission) sponsored a survey to determine what, if any, late ocular effects have resulted from the atomic
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supplemented therefore by lifetime chronic exposure studies on relatively
long-lived species such as the dog, and by a more critical survey of the
fragmentary data available on man in the records of radiologists. The
mouse genetic program recently established at Oak Ridge may be important
in establishing the effects of the low level exposure on large segments
of human population.