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1.
Gastrointestinal Tract
There have been few experiments where the gastrointestinal tract
has been exposed in a menner similar to the one assumed here.
oneof these
fed rats 1.0 to 6.0 millicuries of Yittrium-90 in a single feeding,
with four of the 33 animals dying of adenocarcinoma of the colon and
additional animis dying with acute and chronic ulceration of the
colon.
A second group of rats was given 0.46, 0.20, or 0.06 me of y>ber
feeding over a period of three months with total accumulated amounts of
31.2, 15.6 and 4.68 mc respectively.
Six of the eight animals at the two
higher levels died with carcinoma of the colon and no malignancies were
observed at the lowest level.
The authors made no estimate of radiation
doses.
In another experinent, ’ rats were kept alive by the use of parabiosis
or para-aminoproprio pheuone either pre or post whole-body irradiation of
700-1000 roentgens.
‘our of the 21 rats developed tumors along the
gastrointestinal tract (one each jejunum, ileum, duodenum, and colon),
with four edditional animals showing tumors in other organs.
Lesser doses
have been shown to produce appreciable percentage of intestinal carcinoms
in mice by using fast-neutrons, but this is not so applicable to the present
discussion of beta exposure .©
Further, in comparing gastrointestinal
irradiation only, versus whole body, the question is raised as to any
possible indirect carcinogenic action in the latter case.”
One summarizing statement of the short term effects stated, "--though the gastrointestinal tract is one of the sensitive systems to
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- 10.