Rediske and Selders '5 at Hanford grew barley in soil artificially contaminated with Y and Sr.
Y uptake was lower than Sr by 2 to 4 orders of magnitude.
The same group grew tomatoes in soil contaminated with close-in fallout from a weapon
test. Considerable fractionation had reduced the Sr content of the debris relative to the rare
earth content, and the date of the experiment (1% years after detonation) was such that Sr
activity relative to rare earth was at its minimum. Under these conditions rare earth activity
in leaves was 4 times greater than Sr activity. However, relative to corresponding activities in
the soil, rare earth uptake was 1, that of Sr.
Menzel examined uptakeof rare earths as well as of Ru and Sr by forage crops and vegetables
from soil contaminated with weapon debris similar to that in the Hanford experiment. Despite
reduction of Sr in the soil by fractionation, rare earth activity in the plant leaves averaged 14-the
Sr activity at 1% years after detonation. While the experiments of Menzel and the Hanford .
group are not entirely consistent, both indicate that root uptake of rare earths relative to Sr is
low in the case of actual close-in fallout.
F. Uptake and metabolism of fission products by man and animals:
1. Strontium:
As with plants, the uptake of Sr by man and animals has been studied both by laboratory
experiments and by observations on actual atomic test debris as now present in nature. A few
measurements are available also on stable Sr content of human bones.
a. Laboratory experiments.—The retention of Sr by animals has been examined in numerous
experiments. In Appendix B is a fairly complete collection of data on those experiments which
permit an understanding of Sr metabolism in relation to Ca metabolism. About half of this
information is taken from the publishedliterature.
From these data it may be concluded that when Sr and Ca are administered under equivalent
conditions, the Sr/Ca ratio retained falls between 0.25 and 1.
This was true for:
(1) Wide range of species (mouse, rat, steer).
(2) Wide range of age.
(3) Wide range of carrier Sr.
(4) Conditions of normal or disturbed Ca metabolism.
(5) Oral or injected route of administration.
While most of the experiments have determined comparative Sr and Ca retention over only
a short period of time, the 2 rat experiments, plus the fact that Sr and Ca excretion is low after
the first few days of retention, indicate a similar ratio would hold over longer periods.
These data show that under conditions of widespread environmental contamination, Sr
uptake and retention by animals and presumably by man would be determined by the dietary
Ca status.
The extent of Sr incorporation into milk is an important problem, since milk is the most
important source of Ca in the American diet. Comar has performed experiments on cows in
which the Sr/Ca ratio in feed, blood, and milk was measured under equilibrium conditions.
Typical relative values were 1.0, 0.37, and 0.13 respectively.
In the Sunshineobservations referred
to in the next section, Libby found the Sr/Ca ratio in milk from 10 farms to be 15% of that of
the alfalfa on which the cows were feeding (range 9-36%, with the spread probably attributable
to sampling errors of varioussorts).
b. Observations on weapon test debris in environment.—Human, animal and animal product
samples from the U.S. and foreign countries have been analyzed *. *. '- for Sr-89 or Sr—90.
These data are compiled in Appendix C. The outstanding conclusions are the following:
(1) Dependence of activity on longitude is not large.
Footnote references on pp. 42-43.
Ro
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DOs ARG@HIVEL