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To the Editor of the New York Times:
I have read with interest the letter from Drs. J. Laurence Kulp,
Wallace S. Broecker, and Arthur R. senmwrel nso issue of 2 May 1958.
In this letter they say that my statement that carbon 14 represents "a far

more serious long-term menace than all other radioactive by-products of

an atomic explosion” is incorrect, and

 

“

iL meepeoved— eet eile that carbon 14 will contribute only a

minor fraction of the radiation produced by oe 90 and cesium 131

 

eontirat: When the cumulative damsx dose to the entire Ral ane cncernse over
the total lives of all isotopes is considered, the radiation from the
carbon 14 produced by bomb tests newgmmgpGitendedkemst is found to be Ee
considerably larger than the amount attributed by the AEC to other isotopes,
and the number of defective children that can be predicted to be pro-
duced by the radiation from carbon 14 is far greater than the number
predicted for the other isotopes.

In his 1956 paper on radioactive fallout Dr. W. F. Libby pointed

out that neutrons released in the explosions of nuclear weapons in air

react with nitrogen nuclei to make carbon 14; he said that "fortunately
-2-
safe
this radioactivity is essentially/because of its long lifetime and the
enormous amount of diluting carbon dioxide in the atmosphere." Perhaps
because of a feeling of reassurance engendered by this d statement and

others by Dr. Libby I did not make any calculations of the genetic and

somatic effects of the carbon 14 produced in the testing of nuclear

   

a
weapons until last month.( Zp his 27 March 1958 address in Lausanne,

 

Dr. Libby gave additional information about carbon uf including xhex a
statement kkakx about the amount of carbon 14 generated per megaton,
with fusion and fission weighed as they had actually occurred; this
amount is 7.4 kilograms, about 7 times the amount that he had reported
in 1956 for a pure fission weapon. He stated that a considerable part
of the carbon 14 (which I estimate as two-thirds) falls back as calcium
carbonate, the rest of it entering the reservoire/of which the biosphere
is a part. At the present time the concentration of carbon 14 in the

to
atmosphere has been increased by the bomb tests ky a value 10 percent
greater than its former value. As carbon dioxide dissolves in the ocean,

this percentage will, decrease if the bomb tests are discontinued.

A

I shall calculate the effect of carbon 14 on the basis of the following

TRa Le

assumptions: *A-starmdéesd i of bomb testing Y\ 20 megatons per year;
one-third of the generated carbon 14 is released to the atmosphere; there is
moderately rapid equilibrium with a large reservoir, including the ocean,
with normal content 74,000 kilograms of carbon 14; the mean life of carbon

V

14 is 8070 yearsigthe effect of a single gonad exposure of 0.1 roentgen

  
  
 
 
   
 
  
 
 
 
  
 
  
 
 
   
   
   

of a world population equal to that at present is to cause ultimately a
total of 380,000 seriously defective children (gross physical or mental
defect, stillbirth, childhood death) plus 700,000 sino. ata
deaths, as giuemn estimated by Professor James F. Crow, a member of the
National Academy of Sciences-National Research Council Committee on Genetic
Effects of Atomic Radiation, in his testimony before the Congressional
Subcomhittee on Radiation on 4 June 1957; the population of the world,

over
which has increased by/1 billion during the last 100 years wilt continue

to increasef and will have an average value during the next 10,000 or

20,000 years such that there will be five times as many children born as

 

 

at presentajthe normal amount of carbon 14 in the human body produces a

gonad exposure of 0.0015 roentgen per year, as stated in 1956 hy Dr. Libby}

A straightforward calculation based on the above assumptions leads

directly to the conclusion that 1 year of testing at the standard rate
of 30 megatons per year (2xk$xkmmam two 15-megaton bombs, similar to the

one detonated by the United States on 1 March 1954) will ultimately be
230,000

responsible for the birth of S@i&ye@@0 seriously defective children and

also for 428,000 embryonic and neonatal deaths.

For comparison, we need to have a value of the amount of radiation
produced by the other isotopes. ks The calculation of the effect of
other isotopes is most readily made by the steady-state method. In the
NAS-NRC report of 4 June 1956 it is said that if weapons testing were
continued at the rate of the preceding five years it is estimated that
a total 30-year gonad dose of about one-tenth of a roentgen would be
produced, or, since the accuracy involved is probably not better than a
factor of 5, a dose between 0.02 roentgen and 0.50 roentgen. ‘The value

in 30 years
0.1 roentgen /has been reported as recently as Heuxwary this year, 1958,
in the 24rd Semi-annual Report of the Atomic Energy Commission. It cor-

responds to 0.00535 roentgen per year, and accordingly to the production

of 15,000 seriously defective children plus 23,000 embryonic and neonatal

seston numbers are far less than the numbers predicted as the
2

thats A carbon 14 weeekt per year of testing, and accordingly the statement is justi-

genetic
fied that carbon 14 is a far more serious long-term/menace than the other

products of atomic explosions.

Although the Atomic Energy Commission has not released any statement
about this matter » it seems to me not unlikely that the world-wide fallout
corresponds more closely to the upper limit given by the NAS-NRC committee,

ol retggn os
0.5 roentgen in 430 years, than to the emeeker value A If the upper limit is

   
       
 
 
 
 
 

in fact to be used, the number of defective children Per year of testing

other than carbon 7 becomes 65,000// and the

number of embryonic and neonatal Weaths becomes 115,000 9 These numbers

are still far less than those estimated for #ae carbon 1h, etéecs . On.
the other hand, it must be pointed out that if the world population want te
renaing/ constant// the effect of carbon 14 would be only about equal to
that of the other isotopes, assuming that the other isotopes irradiate the
gonads in amount 0.5 roentgen in 30 years, rather than the usually quoted
value 0.1 roentgen in 30 years.

The somatic effects of the bomb tests are more difficult to discuss,

because they involve more assumptions about the nature of the interaction
of high-energy radiation with the human bodyf and because mmkxukk scientists
are not in such overwhelming agreement as they are about the genetic ef-

fects. I shall content myself with the statement that it is likely

» in the long run,
that the somatic effects of carbon 14 are /roughly equal to those of the

other isotopes, including strontium 90.

rad nar don

The bomb tests carried wasbewené{including 1958, which is starting
Prk
off as a bad year) can be estimated to correspond roughly to J 20-megaton
years. Accordingly we may say that the predicted effect of the carbon
these
14 released in the bomb tests will be to produce about 1 million seriously

defective children and about 2 million embryonic and neonatal deaths,
and that the predicted effects of the other 28@¥SRSS« will be saupredrte
g .
WAL
As other people have pointed out, these numbers Aceresent a minute

fraction of the total number of seriously defective children wees

aeemkans and of embryonic and neonatal sone era Sree

 

a — .

 
 

DE SPT TE OVEN Tiamat or oem Her OSH I feel that

each WAAL LR: human being is important, and that it is well worth while

to calculate the numbers of individual human beings who will be caused

to suffer or to die because of the bomb tests, rather than to talk about

"negligible ettect). * "undetectable increase,” "extremely small fraction."
Linus Pauling

Pasadena, California

8 May 1958