APPENDIX
In the Marshall Islands, twelve children under five
years of age were exposed to heavy fallout in 1954.
Their total body gamma-ray dose was about 175 rads
while their thyroid dose from iodine 131 is estimated
at roughly one thousand rads. Of these twelve children,
two have become hypothyroid with marked growth retardation, while five others have developed adenomatoid
goiters. No thyroid abnormalities have been observed in
the 75 unexposed comparison children from nearby
islands.”
Concerning the St. George children, it 1s uncertain
whether their incidences of non-malignant thyroid abnormalities, such as thyroiditis and thyroid nodules,
were influenced by iodine 131 irradiation.'4 It is also
unknown whether these abnormalities might later have
progressed into cancers if not discovered in the course
of the Utah study and treated surgically.
CONCLUSION
What are the effects of Jow doses of iodine 131 in
children? How safe is the Federal Radiation Council’s
new Protective Action Guide for thyroid doses of 30
rads to individual infants and ten rads to groups of
infants?’ Proper study of the Utah children might provide at least partial answers to these questions.
ACKNOWLEDGEMENTS
OTHER POSSIBILITIES OF IODINE 131
DOSE EVALUATION
The central problem in this study is one of reconstruction in the absence of complete data. Lacking
direct measurements of iodine 131 levels during the
1951-55 tests, estimates have been based on retrospec-
tive calculations of the available data—gross beta and
gamma levels—and on assumptions on the relation of
these levels to the iodine 131 levels.
It is fully recognized that at this point serious objections mayberaised. Firstly, the yields of various radio-
active isotopes have to be assumed in the absence of
full information on the major nature of the fissionable
material used in each explosion. Secondly, our knowledge of the fractionation process is incomplete. Never-
theless it may be useful to pursue these calculations
through as many independent methods as we can find. Not all these methods may prove practicable after
detailed examination, but we cannot afford to reject
suggestions too quickly.
A newpossibility has been pointed out to me by
Merril Eisenbud (Professor of Environmental Medicine,
New York University Medical Center, Tuxedo, New
York). The concept is described by Edwards.'? Both
iodine 131 and iodine 129 result from fission. While
the iodine 131 has decayed because of its short eight-
liminary draft of this paper. These comments were
day half-life, the iodine 129 with its 16-million year
half-life has hardly decayed at all. Thus, the iodine 129
content in the thyroids of people who died soon after
suggestions of some reviewers conflicted sharply with
ficient pathological tissue preserved from autopsies per-
The following individuals made comments on a pre-
very helpful in preparing the final manuscript, although
not ali suggested changes could be incorporated. The
those of others. The listing of reviewers does not imply
their agreement or disagreement with this paper. It
simply acknowledges my appreciation for their help.
Comments were received from: Robert C. Pendleton,
Ray D. Lloyd, Charles L. Dunham, R. John Garner,
E. A. Martell, Victor E. Archer, Leo D. Marinelli,
Roger McClellan, Arthur H. Wolff, Gordon M. Dunning, Lester Van Middlesworth, Cyri! L. Comar, Donald
R. Chadwick, Shields Warren, J. E. Rall, Claire C.
Palmiter, Joshua Holland, Lester Machta, Harold A.
Knapp, Leo K. Bustad, H. David Bruner, Leonard
Sagan, Geoffrey W. Dolphin, Delbert 5. Barth, Edward
S. Weiss, Merril Eisenbud, James G. Terrill, Karl Z.
Morgan, and Sctentist and Citizen. Finally, I wish to
thank the Committee for Nuclear Information for the
Invitation to submit this paper to Scientist and Citizen.
I hope that this article may stimulate thinking on how
best to obtain the information potentially available
from a study of the Utah children. The problem is com-
plex and certainly I do not knowall the answers.
an early nuclear test might indicate the iodine 131 dose
which was received. It may be possible to obtain suf-
formed at that time, and thus gauge the iodine 129
levels.
For example, one microcurie of iodine 131 consists
of 3.72 x 10'° atoms. Thefission yields have been estimated (Weaver, et.al.) at about 3.0 per cent for the
iodine 129 chain, and 4.6 per cent for the iodine 131
chain, from plutonium 239 fission by fission-spectrum
neutrons.” Thus, there are about 2.4 x 10" atoms of
1odine 129 associated with an aittal iodine 131 activity
of one microcuric.
To assay iodine 129 it can be activated to iodine 130
by neutron bombardment.”® A saturation activity of 73
disintegrations per second of iodine 130 (easily counted)
results from the bombardment of 2.4 x 10'° atoms of
iodine 129 (cross-section 30 x 1074 cm? per atom) bya
{lux of 10% neutrons per cm? each second."
Todine 129 atoms are removed from the adult human
thyroid with a biological half-time of about three
months, although this varies from person to person.”!
DOE ARCHIVES
Scientist and Citizen