Айзек Азимов - The Genetic Effects of Radiation

Some geneticists have recommended that the average total exposure of human beings in the first 30 years of life be set at 10 rads. Note that this figure is set as a maximum . Every reasonable method, it is expected, will be used to allow mankind to fall as far short of this figure as possible. Note also that the 10–rad figure is an average maximum. The exposure of some individuals to a greater total dose would be viewed as tolerable for society if it were balanced by the exposure of other individuals to a lesser total dose.

A total exposure of 10 rads might increase the overall mutation rate, it is roughly estimated, by 10%. This is serious enough, but is bearable if we can convince ourselves that the alternative of abandoning radiation technology altogether will cause still greater suffering.

A 10% increase in mutation rate, whatever it might mean in personal suffering and public expense, is not likely to threaten the human race with extinction, or even with serious degeneration.

The human race as a whole may be thought of as somewhat analogous to a population of dividing cells in a growing tissue. Those affected by genetic damage drop out and the slack is taken up by those not affected.

If the number of those affected is increased, there would come a crucial point, or threshold, where the slack could no longer be taken up. The genetic load might increase to the point where the species as a whole would degenerate and fade toward extinction—a sort of “racial radiation sickness”.

We are not near this threshold now, however, and can, therefore, as a species, absorb a moderate increase in mutation rate without danger of extinction.

On the other hand, it is not correct to argue, as some do, that an increase in mutation rate might be actually beneficial. The argument runs that a higher mutation rate might broaden the gene pool and make it more flexible, thus speeding up the course of evolution and hastening the advent of “supermen”—brainier, stronger, healthier than we ourselves are.

The truth seems to be that the gene pool, as it exists now, supplies us with all the variability we need for the effective working of the evolutionary mechanism. That mechanism is functioning with such efficiency that broadening the gene pool cannot very well add to it, and if the hope of increased evolutionary efficiency were the only reason to tolerate man–made radiation, it would be insufficient.

The situation is rather analogous to that of a man who owns a good house that is heavily mortgaged. If he were offered a second house with a similar mortgage, he would have to refuse. To be sure, he would have twice the number of houses, but he would not need a second house since he has all the comfort he can reasonably use in his first house—and he would not be able to afford a second mortgage.

What humanity must do, if additional radiation damage is absolutely necessary, is to take on as little of that added damage as possible, and not pretend that any direct benefits will be involved. Any pretense of that sort may well lure us into assuming still greater damage—damage we may not be able to afford under any circumstances and for any reason.

Actually, as the situation appears right now, it is not likely that the use of radiation in modern medicine, research, and industry will overstep the maximum bounds set by scientists who have weighed the problem carefully. Only nuclear warfare is likely to do so, and apparently those governments with large capacities in this direction are thoroughly aware of the danger and (so far, at least) have guided their foreign policies accordingly.

Radiation, Genes, and Man , Bruce Wallace and Theodosius Dobzhansky, Holt, Rinehart and Winston, Inc., New York 10017, 1963, 205 pp., $5.00 (hardback); $1.28 (paperback).

Genetics in the Atomic Age (second edition), Charlotte Auerbach, Oxford University Press, Inc., Fair Lawn, New Jersey 07410, 1965, 111 pp., $2.50.

Atomic Radiation and Life (revised edition), Peter Alexander, Penguin Books, Inc., Baltimore, Maryland 21211, 1966, 288 pp., $1.65.

The Genetic Code , Isaac Asimov, Grossman Publishers, Inc., The Orion Press, New York 10003, 1963, 187 pp., $3.95 (hardback); $0.60 (paperback) from the New American Library of World Literature, Inc., New York 10022.

Radiation: What It Is and How It Affects You. Ralph E. Lapp and Jack Schubert, The Viking Press, New York 10022, 1957, 314 pp., $4.50 (hardback); $1.45 (paperback).

Report of the United Nations Scientific Committee on the Effects of Atomic Radiation , General Assembly, 19th Session, Supplement No. 14 (A/5814), United Nations, International Documents Service, Columbia University Press, New York 10027, 1964, 120 pp., $1.50.

The Effects of Nuclear Weapons , Samuel Glasstone (Ed.), U. S. Atomic Energy Commission, 1962, 730 pp., $3.00. Available from the Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402.

Effect of Radiation on Human Heredity , World Health Organization, International Documents Service, Columbia University Press, New York 10027, 1957, 168 pp., $4.00.

The Nature of Radioactive Fallout and Its Effects on Man , Hearings before the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, Congress of the United States, 85th Congress, 1st Session, U. S. Government Printing Office, 1957, Volume I, 1008 pp., $3.75; Volume II, 1057 pp., $3.50. Available from the Office of the Joint Committee on Atomic Energy, Congress of the United States, Senate Post Office, Washington, D. C. 20510.

Genetics, Radiobiology, and Radiology , Proceedings of the Midwestern Conference, Wendell G. Scott and Evans Titus, Charles C. Thomas Publisher, Springfield, Illinois 62703, 1959, 166 pp., $5.50.

Genetic Hazards of Nuclear Radiations, Bentley Glass, Science , 126: 241 (August 9, 1957).

Genetic Loads in Natural Populations, Theodosius Dobzhansky, Science , 126: 191 (August 2, 1957).

Radiation Dose Rate and Mutation Frequency, W. L. Russell and others, Science , 128: 1546 (December 19, 1958).

Ionizing Radiation and the Living Cell, Alexander Hollaender and George E. Stapleton, Scientific American , 201: 95 (September 1959).

Radiation and Human Mutation, H. J. Muller, Scientific American , 193: 58 (November 1955).

Ionizing Radiation and Evolution, James F. Crow, Scientific American , 201: 138 (September 1959).

Radiation and the Population , 29 minutes, sound, black and white, 1962. Produced by the Argonne National Laboratory. This film explains how radiation causes mutations and how these mutations are passed on to succeeding generations. Mutation research is illustrated with results of experimentation on generations of mice. A discussion of work with fruit flies and induced mutations is also included. This film is available for loan without charge from the AEC Headquarters Film Library, Division of Public Information, U. S. Atomic Energy Commission, Washington, D. C. 20545 and from other AEC film libraries.

The following films were produced by the American Institute of Biological Sciences and may be rented from the Text–Film Division, McGraw–Hill Book Company, 330 West 42nd Street, New York 10036.

Mutation , 28 minutes, sound, color, 1962. This film discusses chromosomal and genetic mutations as applied to man. Muller’s work in inducing mutations by X rays is described.

These three films are 30 minutes long, have sound, are in black and white, and were released in 1960. They are part of a 48–film series that is correlated with the textbook, Principles of Genetics , (fifth edition), Edmund W. Sinnott, L. C. Dunn, and Theodosius Dobzhansky, McGraw–Hill Book Company, 1958, 459 pp., $8.50.