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015 - Dosage Rates · Percheron horse

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  Speaker 1: Section fourteen of the Genetic Effects of Radiation. This is
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  Speaker 1: a LibriVox recording. All LibriVox recordings are in the public domain.
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  Speaker 1: For more information or to volunteer, please visit LibriVox dot org.
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  Speaker 1: Read by t our Love of Pleasant Hill, California. The
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  Speaker 1: Genetic Effects of Radiation by Isaac Asimov and Theodosius Dovsanski,
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  Speaker 1: Section fourteen dosage rates. Another difference between the genetic and
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  Speaker 1: somatic effects of radiation rests in the response to changes
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  Speaker 1: in the rate at which radiation is absorbed. It makes
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  Speaker 1: a considerable difference to the body whether a large dose
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  Speaker 1: of radiation is absorbed over the space of a few
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  Speaker 1: minutes or a few years. When a large dose is
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  Speaker 1: absorbed over a short interval of time, so many of
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  Speaker 1: the growing tissues lose the capacity for division that death
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  Speaker 1: may follow. If the same dose is delivered over years,
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  Speaker 1: Only a small bit of radiation is absorbed on any
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  Speaker 1: given day, and only small proportions of growing cells lose
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  Speaker 1: the capacity for division at any one time. The unaffected
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  Speaker 1: cells will continually make up for this and will replace
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  Speaker 1: the affected ones. The body is, so to speak, continually
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  Speaker 1: repairing the radiation damage, and no serious symptoms will develop
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  Speaker 1: then too. If a moderate dose is delivered, the body
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  Speaker 1: may show visible symptoms of radiation sickness, but can recover.
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  Speaker 1: It will then be capable of withstanding another moderate dose,
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  Speaker 1: and so on. The situation is quite different with respect
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  Speaker 1: to the genetic effects, at least as far as experiments
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  Speaker 1: with Drosophila and bacteria seem to show. Even the smallest
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  Speaker 1: doses will produce a few mutations in the chromosomes of
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  Speaker 1: those cells in the gonads that eventually develop into sex cells.
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  Speaker 1: The affected gonad cells will continue to produce sex cells
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  Speaker 1: with those mutations for the rest of the life of
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  Speaker 1: the organism. Every tiny bit of radiation adds to the
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  Speaker 1: number of mutated sex cells being constantly produced. There is
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  Speaker 1: no recovery because the sex cells after formation do not
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  Speaker 1: work in cooperation, and affected cells are not replaced by
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  Speaker 1: those that are unaffected. This means, judging by the experiments
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  Speaker 1: on lower creatures, that what counts where genetic damage is
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  Speaker 1: in question is not the rate at which radiation is absorbed,
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  Speaker 1: but the total sum of radiation Every exposure and organism experiences,
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  Speaker 1: however small, adds its bit of damage. Excepting this view,
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  Speaker 1: it would seem important to make every effort to minimize
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  Speaker 1: radiation exposure for the population generally, Since most of the
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  Speaker 1: man made increase in background radiation is a result of
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  Speaker 1: the use of X rays in medical diagnosis and therapy,
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  Speaker 1: many geneticists are looking at this with suspicion and concern.
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  Speaker 1: No one suggests that their use be abandoned, for certainly
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  Speaker 1: such techniques are important in the saving of life and
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  Speaker 1: the mitigation of suffering. Still, X rays ought not to
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  Speaker 1: be used lightly or routinely. As a matter of course,
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  Speaker 1: it might seem that X rays applied to the jaw
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  Speaker 1: or the chest would not affect the gonads, and this
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  Speaker 1: might be so if all the X rays could indeed
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  Speaker 1: be confined to the portion of the body at which
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  Speaker 1: they are aimed. Unfortunately, X rays do not uniformly travel
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  Speaker 1: a straight line in passing through matter. They are scattered
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  Speaker 1: to a certain extent. If a stream of X rays
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  Speaker 1: passes through the body anywhere, or even through objects near
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  Speaker 1: the body, some X rays will be scattered through the gonanths.
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  Speaker 1: It is for this reason that some geneticists suggests that
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  Speaker 1: the history of exposure to X rays be kept carefully
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  Speaker 1: for each person. A decision on a new exposure would
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  Speaker 1: then be determined not only by the current situation, but
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  Speaker 1: by the individual's past history. Such considerations were also an
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  Speaker 1: important part of the driving force behind the movement to
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  Speaker 1: end atmosphere testing of nuclear bombs. While the total addition
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  Speaker 1: to the background radiation resulting from such tests is small,
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  Speaker 1: the prospect of continued accumulation is unpleasant. What's more, whereas
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  Speaker 1: X rays used in diagnosis and therapy have a humane
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  Speaker 1: purpose and chiefly affected patient who hopes to be helped
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  Speaker 1: in the process, nuclear fallout affects all of humanity without distinction,
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  Speaker 1: and seems to many people to have as its end
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  Speaker 1: only the promise of a totally destructive nuclear war. It
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  Speaker 1: is not to be expected that the large majority of
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  Speaker 1: humanity that makes up the populations outside the United States,
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  Speaker 1: Great Britain, France, China, and the Soviet Union can be
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  Speaker 1: expected to accept stoically the risk of even limited quantities
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  Speaker 1: of genetic damage out of any feeling of loyalty to
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  Speaker 1: nations not their own. Even within the populations of the
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  Speaker 1: three major nuclear powers, there are strong feelings that the
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  Speaker 1: possible benefits of nuclear testing do not balance the certain dangers.
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  Speaker 1: Public opinion throughout the world is a key factor then
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  Speaker 1: in enforcing the Nuclear test Ban Treaty signed by the
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  Speaker 1: governments of the United States, Great Britain and the Soviet
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  Speaker 1: Union on October tenth, nineteen sixty three. End of Section
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  Speaker 1: fourteen