undoubtedly is a minute contribution to the total body burden in a highly contaminated environment where the other modes of transport are
permitted to operate over a period of years.
The possibility that in-
halation during the actual fall-out time may provide particles that
will lodge in the lung is not ruled out as a source of critical damage,
but as yet there are no indications suggesting that it requires more
than passing notice and an awareness that it should be watched for.
The water analyses of the SUNSHINE Project and other data indicate that water supplies such as reservoirs will not receive more
than a normal share of fall-out based on surface area.
The water-shed
run-off water does not concentrate strontium-90 in the reservoir.
It
has also been shown that strontium-90 does not reach well water by
leaching through the ground.
It appears, therefore, that water will be
a minor contributor to the total body burden in a highly contaminated
environment.
There are no direct experimental data on humans with regard to
metabolism and excretion on a quantitative basis.
Inferences concern-
ing amounts excreted and amounts deposited in bone are derived from
animal data.
In an attempt to attach significance to the amount of
strontium-90 found in bone, reference is made to the total amount of
fission products released, strontium-90 soil deposition and various
levels in the soil-plant-animal-milk chain.
thus far are well below any hazard level.
The actual values obtained
Their projection to hazard
levels and their quantitative significance will become apparent when
hazerd calculations are discussed below.
It is important to remember that at the end of a year probably
5% pr less of ingested strontium-90 is retained in bone.
In terms of
an equilibrium environment, this principle ceases to be important.
Under these circumstances the ratio of strontium-90/calciumas it is
taken in, corrected for any possible body discrimination between the
two elements, becomes the important factor.
The real situation may be
a@ combination of a high initial intake followed by a continued lower
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