264
RADIOACTIVITY IN MAN
absorbed to produce an acute radiation syndrome before an acute
lethal gamina dose had been received. Ingestion of radioactive
materials exposes the gastrointestinal tract and the thyroid gland
to the largest radiation doses of any organ systems. Radioiodine
probably is the most important radioelement present early in
fallout in viewof its selective concentration in the thyroid gland.
The Marshallese people received near maximum permissible
levels of some isotopes early, but there was rapid excretion so that
by one or two years barely detectable amounts remained.
The return of the Rongelap people to their slightly contaminated
island in 1957 has caused a measurable increase in body burdens of
radionuclides. Cs’ and Zn™ increased by factors up to one hundredfold but, even so, present levels represent only a fraction of
the maximumpermissible levels and equilibrium appears to have
been attained. Srexcretion increased twentyfold during the first
vear after the return of the Rongelap people, with a slight further
increase noted the following year. Marine, plant and animal
studies are part of the radiative ecological aspects of these studies.
REFERENCES
1. Conard, R. .4.. Meyer. L. M., Robertson, J. S., Sutow, W. W.. Wolins, W.,
and Hechter. H.: Effects of fallout radiation on a human population,
Rad. Res. Suppl. 1:280, 1959,
nw
. Conard, R. A.. Meyer, L. M.. Rall. J. E.. Lowery, A.. Bach, S, A., Cannon. B., Carter, E. L.. Eicher, M., and Hechter. H.: March 1957 medical
survey of the Rongelap and Utirik people three years after exposure to
radioactive fallout, BNL 501 (1-119) 21 (Mar.) 1957.
3. Conard, R. A. Huggins, C. E.. Cannon, B.. Lowery, A., and Richards,
J. B.: Medical survey of the Marshallese two years after exposure to
fall-out radiauion, J.AM.A. 164:1192 (July 13) 1957.
wa
4. Gronkite. E. Po. Dunham, C. L.. Grifin, D.. MePherson, S. D., and Woad-
ward. K. T.: Twelve month post-exposure survey on Marshallese exposed to fallout radiations. BNL 384 (1-71) (\ug.) 1955.
. Bond. V. P.. Conard, R.A... Robertson, J. S.. and Weden, E. .A.: Medical
examination of Rongelap people six months after exposure to fallout,
Operation Castle Addendum Report 4.1. W937 ( Apr.) 1955,
6. Cronkite. E. P.. Bond. V. P.. und Dunham, C. L.: Some etlects of ionizing
radiation on human beings. United States Government Printing Office.
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7. Kovama. Y., et al: Irve (published by Iryo Dokokai. Medical Affairs Bu-
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