STRONTIUM-90 IN MILK
unit of quantity of electricity of either sign. The roentgen is a measure of
nuation
on may
ite since
plants,
energy absorbed and corresponds to the absorption of 83 ergs/g of air and
about 93 ergs/g of tissue (4).
,
an
. rep: Physical equivalent of a roentgen and equals 93 ergs/g (4).
. rad: A unit of absorbed dose which is equal to 100 ergs/g (4).
. RBE: Relative Biological Effectiveness. RBE compares the biological effectiveness of radiation from different sources. For 8 particles and y rays,
RBE = 1; for a particles, RBE = 20, and for protons, RBE = 10. This unit is
not precise, for it depends on pH, oxygen tension, and the organ radiated
(19k, 197).
. rem: It is the unit of RBE dose. That is, it includes the RBE and the absorbed dose 1n rads. This unit also has a degree of uncertainty (19n).
. Diserimination ratio: The ratio of strontium to calcium in any product compartment decided by the ratio in a precursor compartment. Comar et al. (5)
express it as the ‘‘Strontium-Calcium Observed Ratio’’: O Rgample-precuraor
‘et some
le spon* causes.
is muta‘hat the
taneous
nt level
rate of
lifferent
ne of a
vel (2).
mth
Sr/Ca of sample
—________———.. For example, an ORguin-aiet of 0.1 means that the diet of a
Sr/Ca of precursor
+
million
The inand the
damage
of life
strontium-90 per gram of calcium (pye Sr-90/g Ca) and is the common unit for
country
describing the concentration of Sr-90 in man (797). It is equal to one-hundredth
of the average permissible body burden of Sr-90 for the general public (0.1yc).
Since the body contains about 1,000 g. of Ca, the maximum permissible amount
of Sr-90/¢ Ca for the average population is equal to 1 K 10-4 we Sr-90/g¢ Ca. The
Sunshine Unit is 1/100th of this value, or equal to puc Sr-90/e Ca.
ym jobs,
antages.
: fallout
its, and
idies in
hat the
if test-
REFERENCES
r peneng but
jologiscular
static
RATE FRAOEnde, MOOR Big Atariys ermMETIRE
te ot
t cause
ntegra-
cow contains ten times as much Sr-90 per unit of calcium as is found in the milk.
This may also be expressed as a Discrimination Ratio, or Factor of 10.
. Sunshine Unit (S.U.): A S.U. is equal to the number of micromicrocuries of
(1) Annersen, EL. C., Scaren, R, L.. FISHER, W. R.. ann LANGHAM, WricHt. Radioactivity
of People and Foods. Science, 125: 1273. 1957.
(2) Anonymous. AEC Committee Views Fallout. Chem. and Eng, News, 35: 49. 1957.
(3) Caster, W. O. Strontium-90 Hazard: Relationship Between Maximum Permissible Concentration and Population Mean, Science, 125: 1291. 1957.
(4) Comar, C. L. Radioisotopes in Biology and Agriculture. McGraw-Hill Book Co., New
York. 1955.
(5) Comar, C. L., Russetn, R. S., anp Wasserman, R. H. Strontium-Caleium Movement
from Soil to Man. Science, 126: 485. 1957.
(6) Comar, C. L., WAassermaAN, R. H., anp Noip, M. M. Strontium-Caleium Discrimination
Factors in the Rat. Proc. Soc. Fzntl. Biel. Med., 92: 859. 1956.
( ) Comar, C. L., Wasserman, R. H., ULLBERG, SVEN, AND ANpDREWs, G. A. Strontium
Metabolism and Strontium-Caleium Discrimination in Man. Proc. Soc. Exptl, Biol.
Med., 95: 386. 1957.
(8) Ecxerman, W. R., Kup, J. L., anp SCHULERT, A. R, Strontium-90 in Man. II. Science,
127: 266. 1958.
(9) Faria, G., Bucuer, J. C., Burnert, C. H., Canrrit, 8, T., GLass, Hi. B., anp Warren, 8.
Statement of Radioactive Fallout (by the Advisory Committee on Biology and Medicine of Sigma Xi). Am, Scientist, 46: 138. 1958.
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