Cc. Lb. Dunhan, M, Dey Directer
October 15, 1958
Division of Biology and Medicine
Garden M. Dunning, Chief, Radiation Effects of Weapons Branch
Division of Biology and Medicine
TODINE~131 MEASUREMENTS OFFSITE DURIIK OPERATION HARDTACK PHASE I
SYMBOL: DBM:REWB :G)
The USPHS offsite radlolnginal monitoring during Operation Nardtack
Phase I on the islands ef Rengelsap, Wetho, Utirik and Ujelang is
the first tine they atteapted te make measurements of iodine~131
by drawing air through a cartridge filled with activated charcoal.
In a draft of their preliminary repert it is stated, "These results
indicate that a significant internal exposure might occur te populations in off-site areas subject te fallout as a result of the
inhalation ef I-131. They further indicate that an off-site sampling
program may not be complete unless it does include a aethod for
determining I-13] levels in the afr."
Since this will be a public decusent I ean foresee the above statements causing undue concern by séue readers. The first sentence
is not fully evaluative and could leave a scare in the minds of readers.
The second sentence might open the AEC te the criticiam of why had
we not dene this during
operations.
I called Mr. Ernest Anderson
(who ecenpiied the report) and discussed the problem with him. He
agreed to rewrite the paragraph.
For your information the collecting point showing the highest
dodine-131 air concentrations, outeide of the Froving Ground, was
Rongelap. The highest sample collected was 125.5 micromicrocuries
per euble meter of iodine-131 averaged ever the 2) hours that it
Was collected. The total expesure te the thyroid from iodine-131,
based upon the USPHS measurements, ever the period of time of cellection
(3 months) that encompassed most of the fallout amounted to about
20 millirads.
This may be compared with the external gama exposure
for the sane perfod of time of about 2865 aillirads.
éc: Dr. Shilling
Dr. Western
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Form AEC=-318 (Rev. 9-53)
U. S. GOVERNMENT PatNTENG OFFICE
16-—-AT74! -3
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