-2somewhat larger dhe to the short-lived iodine isotopes (1) and the yb
from Pacific and Russian tests.
yi3t is a Fission product formed in nuclear explosions.
It and
other products are carried in the air downwind from the point of detanation.
When this fallout settles on pastures,
contaminated.
feed.
the exposed forage becomes
yi3t appears in the milk of cattle ingesting yi31 in their
If wan drinks this radioactive milk,
irreadiates his thyroid gland.
ting thyroid exposure from I
131
yl concentrates in and
These processes suggest 5 ways for estimaThey are listed in decreasing order of
valicity in Table 1 and will be discussed separately.
Table lL
moowr
WAYS OF ESTIMATING THYROID EXPOSURE
it in thyrcid gland
I
in milk
Gamma activity in pastures
Beta activity in air
Fission yield and fallout trajectory
mHyRoD
The most direct way to evaluate I 131
measure its I
131
dose to the thyroid is to
contest by »~rey counting.
We measured yb! in 24 people
during the Utah nm. fartdent of 1962, but unfortunately failed to include
sitea se 43) Qrildren 0-2 years old are regarded as
most
a
'geaiation damage because of “@) the emall size of
ach
aq
ioe presumed greater sensitivity to irradiation and
appear.
A drawback to thyroid count ing is that specialised equipment is
required and only a Limited mmber of people cen be evaluated.
p. 2) my wrx
Fresh milk is by far the major source of fallout yi for our