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SESSION IV DISCUSSION
SOLDAT: I recently read a British document* which discussed ingestion hazards from fission-product contamination on vegetation. In
this document it was assumed that all fission products would be removed from vegetation with a half-residence time of 14 days. This time
would be that superimposed upon the radioactive half-life. For ‘I
this turns out to be about a five-day total combined (effective) half-life.
I assume that only particulate material is concerned here. Some of
you may be familiar with this document. Since hazards mostly from
fallout were evaluated, I would expect that the material is particulate.
This is an indication that, at least for purposes of first approximation,
some people have assumed that there is a uniform residence time
regardless of nuclide.
There is one other comment I would like to add in view of the
CERT tests that were discussed by Dr. Hawley. We had a small test at
Hanford in July 1963 in which we had some human volunteers stationed
some 200 m downwind; the uptake of ‘I from inhalation was about
25%. The breathing rate of these individuals was calibrated before the
release and was about 0.5 cm*/hr, or about half of the working value
used by the International Commission on Radiological Protection as a
standard for man. However, these people were at rest at the time.
They were Sitting in the expected path of the cloud.
WARD: Dr. Thompson, with regard to cesium, would you recommend urine analysis to predict cesium intake? This is of particular
interest to me becauSe we are planning such an experiment. Do you
think this would be an adequate way of judging the intake?
THOMPSON: I think it is quite obvious from our graph that urine
analysis has extreme limitations. Maybe Dr. Lengemann would like to
commenton this.
LENGEMANN: We have data on intake and urinary excretion of
‘radiocesium by both cows and rats. We, however, have not yet attempted
to analyze the data for the correlation. This is to be done in the near
future. A preliminary look at the data suggests that the correlation
should be quite good.
WARD: I was thinking about a human diet.
LENGEMANN: Although we have no data for such an inference, I
feel that it should also be a good correlation for the human.
BENINSON:I have a point ofa general nature. It is on the relevance
of the average and of the scatter in contamination of the diet. Is it
really important to identify the extreine values at the levels we are
*Home Office, Science
Advisors
Branch, Basic
Assumptions
for Use in
Assessment of the Radiological Hazard to Food from Fallout, British Report
SA/PR-40(Rev.), May 1962.
WH