23 August 1958
Dr. W. B. Lewis, F.R.S
13 Beach Avenue
Deep River, Ontario, Canada
Dear Dr. Lewis:
I am especially grateful to you for your letter of 17 August, because it is the only
one, of the 100 that I have received so far in acknowledgment of copies of my book
that I sent to the writers, in which an effort is made to give me some constructive
I regret that you have found my processes of argument as distasteful as those of Drs.
Libby and Teller. I know how great the temptation is to present only those facts
that support one's convictions, and I have been striving to make my presentation an
over-all balanced one. May I ask that you write me in more detail? I have not been
able to understand your critical remarks - that is, it has seemed to me that in general
your criticisms are without basis, and it is for this reason that I should like to
have you write to me again.
Let me discuss the statements that you make in the second, third, and fourth paragraphs
of your letter, in order that you may see why I am having difficulty in understanding
your criticisms. In the second paragraph you say that the sentence at the top of
page 81 could be transposed. You transform it to read "A very small amount of radiation
may do no harm whatever to a person; but a very small amount of an ordinary chemical
poison (e.g. nitrogen mustard) may harm him in such a way as to cause him to die or
to have a seriously defective child."
It seems to me that the first part of your sentence is not true, in the sense in which
I was writing on page 81. Geneticists in general (that is, essentially without exception)
agree that the mutagenic effects of radiation are proportional to the amount, without
As to the second part of your sentence, I would say that I do not consider nitrogen
mustard an ordinary chemical poison. I did not want to confuse my argument and expand
my book by mentioning the exceptional case of chemical mutagens. That is the reason
that I introduced the adjective ordinary. I feel that it is justified for me to say
that a chemical mutagen is not an ordinary poison.
Moreover, I have significant doubt as to whether a chemical mutagen, in particular
nitrogen mustard, has a mutagenic effect proportional to the dose. There are no significant
experiments on this matter, whereas there are significant experiments for radiation.
Moreover, theoretical considerations do not give a clear answer. I have recently
been trying to work out a detailed molecular theory of the mutagenic action of chemical
mutagens, and I found that in the theory that looked best to me I was making use of
two molecules of the mutagen, rather than only one. If this theory should happen
to be the right one, then a small amount of a chemical mutagen—I should say a very
small amount, to conform to the sentence at the top of page 81—would have an extremely
small effect. An amount one hundredth as great as an ordinary amount would have an
effect only one ten thousandth as great. Consequently I have doubt as to the justification
for the second part of your sentence. However, I contend, in any case, that the presentation
that I give on pages 80 and 81 is a good one.
I judge that the second part of your paragraph two depends upon the first part. I
do not understand what criticism is involved in the second part of your paragraph
Your third paragraph relates to carbon-14, and you say that it seems to you that my
argument is in scientific error. I am pretty sure that it is not in error. The factors
that you mention—the tying up of carbon-14 in trees, and so on, have all been taken
into consideration in my calculation. We have experimental verification of the correctness
of the methods of calculation in the materials-balance calculations made by Libby
for cosmic-ray carbon-14. I must, then, reject your statement that there is an error
in my carbon-14 calculations, although if you were to write to me in enough detail
for me to understand the basis of your statement, I should be glad to go over it carefully,
because I know that I, like other human beings, am not infallible.
I may say that the way in which my results are obtained has been illustrated by a
somewhat simplified calculation published on the editorial page of the New York Times
for 16 May 1958 . Nobody has published any criticism of my communication of 16
May 1958 to the New York Times, and no one has written any criticism to me. Doctors
Kulp, Braecker, and Schulert had significant reason for criticizing me and pointing
out any error that I might have made, in case there were an error, and their silence
is, I think, significant. In fact, I have had two telephone conversations with
them (Dr. Kulp), in which I asked him to point out any error in my calculation, and
I have written several letters to these authors, without getting a reply. In the
telephone conversations Dr. Kulp was silent when I asked him about errors in my calculations.
Also, I may say that I have written a detailed paper, about 20 typewritten pages,
for publication in Science. Publication of the paper has been held up, while a referee
examined it—carefully, I hope. At any rate, I have now made small revisions in the
wording, in accordance with the recommendations of the referee, which were, in fact,
criticisms of my wording. The referee did not have any criticism of the calculations
themselves to make. I hope that my paper on carbon-14 will be published within another
six weeks or two months.
Consequently I have a reasonably strong conviction that you are not justified in saying
that my argument about carbon-14 is in scientific error. Again let me say, however,
that I recognize the possibility that it is, and I request that you write to me again,
with a sufficiently detailed discussion of the point to permit me to understand it.
As to your paragraph three, I should like to point out that the ions that are produced
by radiation are not of the same type as those produced by hydrolysis. The latter
ions, involving in general often transfer of protein from a molecule such as a carboxylic acid to a water molecule,
or the separation of a molecule such as sodium chloride into sodium ions and Chloride
ions, are, of course, not a cause of damage to the human body. However, the process
of ionization by high-energy radiation is one of electronic ionization, in which an
electron is removed from a molecule, leaving an ion that is also a free radical.
Ions of this sort do not in general occur naturally (except, of course, as produced
by natural high-energy radiation).
In writing my book I have made an effort to make statements that would give the right
impression to the ordinary reader, and at the same time represent the truth as accepted
now by scientists. I have had enough experience in writing to know how difficult
it is to do this, and I have not hoped to have complete success. I am troubled that
you have been dissatisfied. If, as I think to be the case, your dissatisfaction is
based upon a misunderstanding of some of the scientific points, I shall not be so
troubled. In any case, I hope to benefit by your further criticism, so that, if a
second edition of the book should ever be published, I might be able to make some
I shall look forward to hearing from you again.