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UCRL-3644
2. The bones of stillborn humans have a much lower Sr?" content
than those of year-old children. The Ssr?9 content of children's bones, which
may be averaged from the Libby report,
is given in Table IV.
This table is
representative of the Sr?9 concentration observed in children of early ages at
two study intervals, namely 15 September 1954 and 1 August 1955, average
collection dates. Newborns (stillbirths) have a much lower Sr70 concentration,
because the uterine source of Sr?9/Ca has some intermediate value between
dietary Sr?9/Ca and adult tissue—bone Sr90/Ca. The value for stillbirths, as
of January 1955, is 0.31 pC Sr?9/g Ca; at this same time, growing children,
age 0 to 5 years, are laying down Sr?9 at 2 pC Sr 90 /g Ca. Thus, the fetal
tissues appear to have available to them only 0. 31/2 = 0.16 as much Sr?9 as
the growing child. This is a reasonable fraction, considering the lesser relative amount of milk products consumed by the average mother and the fact
that her tissue stores of calcium are largely from the pre-fallout era. The
growing child at each interval of growth (i.e.,
0-1 year,
1-2 years, etc.)
dilutes the entering Sr99 /Ca by the existing quantity of sr?9/Ca already present
in the body. However, analysis of the increment increase in Sr99 content
shows that children of all ages are consuming and laying down equivalent con-
centrations of Sr?99 /Ca, and that in January 1955 this concentration was approx-
imately 2 wwe S199 /g Ca.
On this date, three sources of milk showed the following ratios:
Radiostrontium content of milk samples, January 1955
(wu Sr99/g Ca)
Foreign cheese?
2.0
Chicago milk?
1.9
New York milk’
1.6
Since growing children have milk as their chief source of Sr?9, it is as expected
that the value of milk closely approximates the concentration of Sr?9/Ca being
deposited in growing bones. These values imply that, should milk remain as
it was in January 1955, all children. born close to this date will eventually have
in their bones an average concentration of Sr99 of 2 BEC S199 /g Ca.
However, the milk Sr?9/Ca is increasing, and has been increasing
since monitoring of milk was begun in 1953. Eisenbud's report’ gives the
following.
"Merril Eisenbud, Global Distribution of Radicactivity from Nuclear Detona-
tions with Special Reference to Strontium-90, Washington Academy ofSciences,
Fall Symposium, November 15,
1956, Washington,
D.C.