Table 10--ALLOWABLE MEGATONSOF FISSION ENERGY RELEASE AS A FUNCTION OF
VARIOUS GENERAL POPULATION MPL’s
Ay, max.
bone level
(no more
Source of equilibrium bone
level estimate and region
United States
Libby (13)-Ecological data
Allowable MT of Fission yield
testing)
puc/g of Ca
10 puc/g
of Ca
50 pyc/g
of Ca
100 puc/g
of Ca
1000 puc/g
of Ca
3.9-—1.7
130 —-30C
650--1500
1300-3000
13,060—30,000
Kulp (6)-Ecological data
2
250
1250
2500
25,000
Eisenbud (76)-Milk data
4
120
600
1200
12,000
This paper-Bone data
1.9
250
1250
2560
25,000
Kulp (28)-Bone data
This paper-Ecological data
North Temperate Latitudes
This report-Ecological data
This report-Bone data
World Average
Kulp (6)-Ecological data
This report-Ecological data
This report-Bone data
1.5
300
3.5
140
1500
700
3000
1400
30,000
14,000
3.6
140
T00
1400
14,000
1.9
250
1250
2500
29,000
1.3
3.1
380
160
1900
800
3800
1600
38,000
16,000
1.7
150
1500
3000
30,000
2
250
1250
2500
25,000
World Average (no factor for
distribution)
Average x 1/5 (for nonuniformity)
Average x 1/10 (for nonuniformity)
50
25
250
125
500
250
5,000
2,500
TET EG
The most important question regarding the potential hazard of long-range Sr*® fallout is
in relation to future weaponstesting. If there is an upper limit to the amount of Sr® in the bones
of the population that can be safely tolerated, then the megaton equivalents of fission products
that can be contributed per year to the biosphereby all nations is limited.
If Sr® contamination from weapons testing by all nations continues at the same rate as
has occurred during the past 5 years, equilibrium will be reached in about 100 years. At equi-
librium the amount of Sr®® which will disappear each year from the environment, due to radioactive decay, will equal the amount that is being produced, and continuing weaponstests will
not result in any further increase in the population bone levels.
Libby'*1" and others!® have predicted that soil and bone levels at equilibrium with the
present test rate will be 8 to 13 times the present values. On the basis of present average
maximum equilibrium Sr®° bone levels postulated from the considerations set forth in this
paper, the bones of the United States population will reach a steady state with the present
testing rate at a value of 17 to 31 pyc per gram of Ca. The equilibrium value for the weighted
average world population will be 15 to 28 pyc per gram of Ca.
Libby’* has stated that something between 5 and 20 pyc per gram of Ca would be the aver-
age maximum Srconcentration in the bones of the United States population if testing continued
indefinitely at the average rate of the past 5 years. Kulp?® predicted an equilibrium level will
be approached in the North American population of about 8 uc per gram of Ca in about 50
years, and Neuman’? in testimony before the Congressional Subcommittee suggested equi-
librium bone levels of about 90 puc per gram of Ca may be reached in the northern United
States. The values given above show disagreement by a factor of about 10. If, however, we accept as a reasonable average the values developed in this paper, the average Sr*° radiation
dose to the bones of the population of the northern United States, at equilibrium with continued
testing at the past rate, may be about 20 to 30 per cent of the average radiation dose from
natural background, or about 20 to 30 per cent of the maximum permissible level adopted by
the National and International Commissions. Since individual variations may result in a small
number of people accumulating Sr*® burdens that are 5 times the average, the radiation dose
to these few individuals may approach as an upper limit 100 to 150 per cent of the recom-
305