.
during purification (10). Indeed, the low
RNA/DNA ratio (1:3) reported by
Smith and Stoker (//) for Coxiella burnettt may reflect such losses and suggests
. the physicochemicallability of rickettsial
RNA.
The differences between the results obtained at 36°C and at 4°C suggest the
participation of enzymatic processes in
the loss of nucleic acids from the rickettsiae. Since the omission of glutamic
acid did not influence the experimental
results, “energy metabolism” does not
seem to be of importance. The present
findings are perhaps analogous to the
degradation of RNA in resting cultures
of Escherichia coli H, which has been
reported by Stephenson and Moyle (7/2).
The foss of nucleic acids from R.
moosert upon incubation at 36°C may be
one of the reasons for the concomitant
inactivation of the biological properties
of this organism.
Z. A. Coun, F, E. Haun,
W. Cectowskl, F. M. BozEMAn
Department of Rickettsial Diseases,
Walter Reed Army Institute of
Research, Washington, D.C.
References
M. R. Bovarnick and E. G. Allen, J. Bac-
teriol. 73, 56 (1957).
» J. Gen. Physiol. 38, 169 (1954).
Np
C, L. Wisseman et al., J. Immunol, 67, 123
(1951).
R. B. Roberts et al., Carnegie Inst. Wash.
Publ. 607 (1955).
SN
wre
1.
CG. H. Fiske and Y. Subbarow, ibid. 66, 375
{1925).
W. J. Mejbaum, Z. physiol. Chem. Hoppe-
Chem, 161, 83 (1954).
Seyler’s 258, 117 (1939),
G. Cerriotti, J. Biol. Chem. 198, 297 (1952).
E. Chargaff and J. N. Davidson, The Nucleic
Acids (Academic Press, New York, 1955), vol.
II, chap, 16.
10. H. Ris and J. P. Fox, J. Exptl. Med, 89, 681
(1949).
11. J. B. Smith and M. G. P. Stoker, Brit. J.
Expil. Pathol. 32, 433 (1951).
12. M. Stephenson and J. M. Moyle, Biochem.
J. 45, vii (1949).
eo
.
.
G. Schmidt and §. J. Thannhauser, J. Biol.
4 October 1957
/
f
Barium-140 Radioactivity \
in Foods
We wish to report the presence of the
fission products barium-!40 and lanthanum-140 in certain foodstuffs in the
United States during periods of nuclear
weapons tests. The presence of these
nuclides in the amounts observed in no
way constitutes a hazard; it carries none
of the potential implications associated,
for example, with strontium-90. It is of
practical concern primarily to those engaged in measurements of radioactivity
near the natural levels, and when an ac-
curate summation of total radiation is
desired. As in the case of cesium-137
({}, measurements of barium-140/lanthanum-140 may also be of value in the
study of the fallout process.
7 FEBRUARY 1958
Barium-140 has a halflife of 12.8
days, and its daughter laathanum-140
has a half-life of 40.2 hours. Because
of their somewhat similar biochemistry
and the short half-life of lanthanum,
secular equilibrium is likely to be maintained in biological systems, and both
nuclides will follow the chemistry of
barium. The biochemical behavior of
barium-140 is similar to that of calcium
and of strontium-90, but the short halflife of barium-140 and the larger biological discrimination factors against it
render it potentially much Jess dangerous than strontium-90.
The presence of barium-140 was first
noted in some deer in New Mexico dur-
407938
SOT TTT OTT
x“ 20-
J
=
* NEW ORLEANS, LA.
“|
4 BISMARK,N.D.
uJ
A
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x
4
4
wif
4
5 04;-
=
g
© as
4
~
ao
7
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E
ott
,
lo 20
10
MAY
20
JUNE
1 20
!o
JULY
20
AUG
I957
ing the summerof 1956—presumably the
Fig. 1. Typical curves of upper channel
activity versus date, for Bismarck, N.D.,
and New Orleans, La.
large 4x liquid scintillation counter designed especially for the measurement of
radioactivity at natural levels in people
channel occurred at other sampling
points during the summer months, at
none of them did the increase reach this
level. Thirty-seven points are routinely
sampled.
The dates reported in Table 1 are
those on which the samples (50 to 100
pounds of nonfat-dry milk solids) were
result of the United States nuclear test
Operation Redwing. It was detected and
identified (by its haif-life} by means of
the Los Alamos human counter (2), a
and foodstuffs. A threefold increase was
noted in the gammaactivityin the spec-
tral region from 1! to 2 Mev (normally
potassium-40 only). This corresponds
roughly to a barium-140 activity of 0.03
wc per 70 kg, which is 6 percent of the
received at Los Alamos. In general, the
on the basis of the “large population”
value (3). A cow taken directly from
the New Mexico range showed a similar
tion with meteorological data, the actual
beef did not, perhaps because of different feeding habits or because of the time
lag between slaughtering and the ap-
Table 1. Barium-140 peak levels in milk.
maximum permissible amount for man,
amount of barium-140, bat commercial
pearance of the meat on the retail market. While the apparent potassium-40
activity of milk samples showed a few
instances of slight increases during 1956,
it was not possible to identify the excess
activity.
Barium-140 appearedin several United
States milk samples during the months
of June, July, and August, 1957, pre-
sumably as a result of distant fallout
from the test operation in Nevada, Operation Plumb-bob, and perhaps from test
operations of the U.S.S.R. Identification
of the excess activity in the potassium
region of the spectrum was again possible on the basis of the measured halflife. Confirmation of the assignment of
the activity to barium-140 was obtained
by spectral analysis, for which an 8- by
4-inch sodium iodide crystal in a steel
room similar to the installation devel-
oped by Marinelli and his coworkers
at the Argonne National Laboratory
(¢} was used. All five of the prominent barium-140/lanthanum-i40 gamma
peaks were identified.
Table { summarizes dates and concentrations of barium-140 in powdered milk
for those locations at which the barium140 gamma activity exceeded that of
natural potassium-40. While detectable
increases in activity in the upper energy
ae
vn
}~
= 08
delay between production andarrival is
about 1 week, and for accurate correla-
production date must be ascertained,
Estimated
Date received
(1957)
barium-140
content
(myuc/lit of
whole milk)
Bismarck, ND.
7 Aug.
2.2
20 Aug.
0.85
Idaho Falis, Idaho
10 June
0.40
9 Aug.
0.46
5 Aug.
0.32
26 Aug.
0,54
Payette, Idaho
19 June
0.12
Louisville, Ky.
21 July
0.27
9 Aug.
0.46
New Orleans, La.
15 July
0.36
20 Aug.
0.19
Willows, Calif.
10 June
0.31
Ladysmith, Wis.
16 Aug.
0.23
Des Moines, Iowa
9 Aug.
0.18
Ogden, Utah
19 June
0,06
af
14 Aug.
O15 are :
Monroe, Utah o ete
11 June
25 July
0.09:
0.12
283
a