level of intake.
Under these conditions the growing body would tend to
stabilize at the lower level, but the added early high intake might be
a factor worthy of assessment.
For example, the suggestion has been
modet2/ that proper interpretation of 1 microcurie as the maximum permissible concentration in an sdult, based on the radium type of experience, would allow between 1.5 and 5.0 microcuries strontium-90 in bone
one year after initial exposure, in order to be equivalent to 0.5 to
1.0 microcurie 25 years later.
The 1.5 to 3.0 microcuries would be 5%
or less of the initially ingested
dose.
This reasoning points up the
meaning of the body burden as found in the human radium cases with regard to extrapolating back to initial exposure.
In a uniformly con-
taminated environment this problem will not require consideration.
In a uniformly contaminated environment it is possible to
calculate the relationship between strontium-90 in the diet and that
which will deposit in bone.
Animal uptake studies of daily radio-
strontium intake indicate that bone retention will, within a period of
weeks, reach a maximum and that the relationship between the maximum
bone radio-strontium level and the radio-strontium intake may be described by
A= Ae x Sr,
8
Sr£
where
A, = maximum attainable bone radio-strontium level
Ap = quantity of radio-strontium consumed per day
Sr_= quantity of strontium in bone
Sr£ quantity of strontium consumed per day
The bone strontium content has been measured and found to be
approximately 0.67 gms.
4a/
‘The daily intake of strontium is epproximately
Stover, C. N., Second Annual Conference on Plutonium and
Mesothorium, University of Utah, Jume 1954.
108