From Paul Langley.
1963: Radio Strontium Levels in Human Breast Milk
JARVIS AND OTHERS: STRONTIUM-89 AND STONTIUM-90 LEVELS Canadian Medical Association Journal. Jan. 19, 1963, vol 88
Strontium-89 and Strontium-90 Levels in Breast Milk and in Mineral-Supplement Preparations
ANITA A. JARVIS, M.A., M.D.,’ JOHN R. BROWN, M.B., Ph.D.t
and BELLA TIEFENBACHJ Toronto
Note: S.U. = Sunshine Unit.
….. In a previous investigation we reported that
human milk, collected from subjects living in
the Toronto area, had a lower ratio of strontium-
90 uuc./g. Ca (S.U.90) than that found in cows’
milk, obtained during the same period. This study
was carried out at a time when the strontium-90
levels were generally low.
Following the resumption
of nuclear testing it was of interest to ascertain
whether human milk will continue to have lower
strontium-90 and S.U.90 levels than cows’ milk and
to study the time-lag between the appearance of
radiostrontium in cows’ milk and human milk.
As well as significant amounts of strontium-
90, fresh fallout contains a considerable quantity
of strontium-89, which fortunately has a relatively
short half-life (54 days as compared with 28 years
for strontium-90). (Paul’s note: this is the old half life for Sr89, which was found
to be incorrect in 1941. A future post will compare all the fission product strontium isotopes. There are at least 5 of them. When disclosing Project Sunshine in, from memory, 1954, Libby of the AEC spoke only in terms of Sr90 to the public.) short length mother of the bride or groom collections
It is also, like strontium-90, a Beta-emitting,
bone-seeking radionuclide, but owing to
its relatively short half-life, it is present only in
fresh fission products, where its concentration may
be 100-150 times that of strontium-90.
Strontium-89 may be initially the more hazardous material,
Because in addition to its greater fission abundance
it has a greater specific activity.
Shorter-lived isotopes have a greater specific activity than long lived
isotopes because they emit particles at a
faster rate and therefore produce a higher intensity
of radiation, other things being equal.
The chemical and metabolic similarities between
calcium and strontium have stimulated prophylactic
and therapeutic attempts to decrease the retention
of strontium by incorporating stable calcium in the
diet of experimental animals and man. Spencer et al
have reported decreased retention of radiostrontium
following the injection of calcium gluconate
intravenously into human subjects.
Wasserman and Comar and Wasserman, Comar and
Papadopoulau have also shown that in the growing
rat the skeletal retention of radiostrontium could
be lessened by the increase of stable calcium in
the diet. They also showed that elevated calcium
levels would almost proportionally decrease the
total body burden of strontium in immature rats.
It is a widespread custom to administer to
pregnant and lactating women, mineral-supplements
high in calcium, with or without vitamins.
Strontium isotopes, if present in these preparations,
will ultimately be transferred to the fetus and to
the breast-fed infant. In view of this it was thought
to be expedient to examine the calcium, strontium-
89 and strontium-90 content of several commercially
available calcium compounds used in the
manufacture of prenatal and lactational mineral supplement
preparations.
ABSTRACT
Strontium-90, strontium-89 and S.U. values
were determined in human milk before and
after the resumption of atmospheric nuclear
testings in 1961, and the levels were compared
to cows’ milk values reported during
the same time. S.U.90 levels in human milk
were approximately one-fifth of those found
in cows’ milk. Assuming an average dietary
intake of 11-13 S.U.90 during the period
tested, the mean strontium/calcium ratio of
1.78 found in human milk represents an
Observed Ratio milk-diet of approximately
0.14-0.16.
Although strontium-89 was present
in cows’ milk already in September
1961, it did not appear in human milk until
November 1961. It seems, therefore, that
there was a two-month lag period between
the appearance of fresh fallout in cows’
milk and human milk.
Calcium-supplement mineral preparations used
by pregnant and lactating women were
tested to find their strontium-89, strontium-90 and S.U. levels,
because strontium isotopes, if present in
these products, will be transferred to the
fetus and to breast-fed infants. The compounds
tested had S.U.90 levels of 0.13-
2.62; in none of the preparations was Sr89
present.
End quote.