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Evolution in time of specific activity:
Tw samples for the
evolution of specific activities (in microcuries 1232/i¢g dry saterial )
are shown in graphs 1 and 2,
We verify that the effective half-Lives
of 1131 in the grase (per gram of dry material) are 4,5 + 0.72 days
during the first experiment (1963) and 6,0 + 0.93 days during experi~
mant 2 (1963); the corresponding biological half-lives are, respectively,
10.2 + 2 days and 23.5 + 4,3 days,
Contamination of the Milk
Time required for the appearance of 1131 as a function of the
moment of contamination:
graph 3 showa the evolution of the relative
concentration of 1251, tn relation to the saximum observed peak, as
a function of the moment of the day in which contaminet{on occurred.
predetermined time in a contaminated pasture was equivalent at this
moment to a pasture occupied by the Livestock.
a.
151 activity secreted in the milk:
curves:
Shape of the secretion
placing 3 cows (A,8,C) in contaminated pasture in June,
July, and September, 1962, has produced allk wita 1392 content
per liter as show {fn graphs 4, 5, and 6.
Rainfall (date and height in am) is also show: in the
graphs.
The secretion curves obtained in the special cases of the
firet tw experinents In 1963 are giten in gmphs 1 and 2.
b, 131 activity In milk, expressed in percent of the daily ingested activity.
Given the practical impossibility of deter-
mining the quantity of fresh grass consured caily by each of the
cows, in the case of the free pasture experiment, we nade in 1963
Pee chenaaHeeRS
In our tests, we have assumed that placing the Livestock at a
: