- 21 -
is very low in calcium and as a result grows grasses of high
radiostrontium content.
Of course, it is clear that Tertilization with calcium will immediately relieve this di:ficulty,
but in the absence of such fertilization, the questica is:
How serious is the effect of calciun deficiency in promoting
strontium-90 pick-up through the food chain?
As was remarked earlier, there is an averaging
which occurs in food distribution systems and calcium deficient
Soils are naturally rather poor producers and as a consequence
the weight of the food so produced is less than for a good
well fertilized, well balanced soil. This factor reduces the
flow into the general food system of material of exception-
ally high strontium-990 content.
It therefore will probably
be sufficient to consider the radiostrontium of milk, since
milk is the main source of calcium, in order to test for the
radiostrontium content of the food in given areas.
Direct
measurements have shown that a factor of five encompasses the
total variation due to all factors including calcium deficiencies in acid scils.
The general intake must depend on the food distribution pattern and the relatively small fluctuation in milk
contents must reflect this. The number of individuals who
rely totally on the food output of soil of very low calcium
content is very small indeed, but it.must be true that
these individuais if they grew up on such a provincial,
isolated farm would have as much as ten to 50 times the
normal average strontium-90 content. The normal calcium
concentration in soils in the United States is about 20
grams per square foot for the top 2.5 inches and about
the poorest Soil known has about 0.4 gram available calcium
per square foot for the top 2.5 inches--a deficiency factor
of 50.
It is clear from a detailed examination made by
the author for people living in calcium deficient areas with
normal food distribution patterns, that a factor of 5 is about
as large an effect as can be expected from a fifty-fold
deficiency of calcium in the soil. The food from outside of
the calcium deficient area reduces by a factor of about ten
the increase in strontium-90 pick-up rate which would be expected from the calcium deficiency in the soil if people lived
ee
rn
ri
5
m1
F
k
Fa
Ri
4
i
m4
re
py
“
pe
pee
Fa
(more)