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The average concentration of I 131 measured on samples of leafy
vegetables collected from local farms and vegetable markets during the
period of May through September was less than or approximately equivalent to the detection level of 0.05 pce/g.
Considering a consumption rate of
100 g cf leafy vegetables per day throughout the 5 month growing season,
the average annual intake from local vegetables would be about 750 pc yi3),
Such an intake implies an annual exposure of about 1 mrem to the thyroid
of a "standard man".
G.
Concentrations of I
131
in Cattle Thyroids
The collection of thyroids from cattle slaughtered at Pasco was
initiated in 1960 and then broadened in 1962 to include collection of thyroids
of cattle slaughtered at Moses Lake, Toppenish, Walla Walla, and Wenatchee.
Since the concentration of yi31 in bovine thyroids is about 2 orders of magnitude higher than that in the pasture grass or in milk, it is advantageous to
131
.
.
‘ measurements to follow probable trends in
use thyroid
concentrations of I
in milk and farm produce when the levels in milk and vegetables are too low
for practical measurement.
The sensitivity of cattle thyroids is evident
from the significant increase in p31 concentrations observed for a short
period in September following the unplanned release of I
chemical separations facilities (Figure 16).
131
from one of the
The maximum concentration,
however, was only 62 pc/g which was considerably less than levels observed
in late 1962 and early 1963 as a result of I 131 from fallout.
Data obtained from the cattle thyroid program for 1963 are presented
in Appendix B, Table 4.
H.
Radioactive Particulates in the Atmosphere
Air sampling stations are maintained at several locations within the
Hanford reservation and at several sites throughout the Pacific Northwest.
Sample filters are changed weekly by cooperating agencies at Seattle, Spokane,
Walla Walla, and Yakima in Washington; Meacham and Klamath Falls in
Oregon; Boise and Lewiston in Idaho; and Great Falls, Montana.
These filters
are sent to Hanford where they are analyzed for total beta activity.
Individual