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012 - Man-made Radiation · Percheron horse

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  Speaker 1: Section eleven 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 KUBI The Genetic Effects of Radiation by Isaac
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  Speaker 1: Asimov and Theodosius Dobzansky. Man made radiation. Man began to
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  Speaker 1: add to the background radiation in the eighteen nineties. In
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  Speaker 1: eighteen ninety five, X rays were discovered and since then
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  Speaker 1: have become increasingly useful in medical diagnosis and therapy and
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  Speaker 1: in industry. In eighteen ninety six, radioactivity was discovered and
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  Speaker 1: radioactive substances were concentrated in laboratories in order that they
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  Speaker 1: might be studied. In nineteen thirty four, it was found
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  Speaker 1: that radiactive forms of non radioactive elements radioisotopes could be formed,
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  Speaker 1: and their use came to be widespread in universities, hospitals,
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  Speaker 1: and industries. Then, in nineteen forty five, the nuclear bomb
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  Speaker 1: was developed. With the uranium or plutonium fission that produces
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  Speaker 1: a nuclear explosion, there is an accompaniment of intense gamma radiation.
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  Speaker 1: In addition, a variety of radioisotopes are left behind in
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  Speaker 1: the form of the residue fission fragments of the fissioning atoms.
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  Speaker 1: These fission fragments are distributed widely in the atmosphere, Some
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  Speaker 1: rise high into the stratosphere, and descendants fall out over
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  Speaker 1: the succeeding months and years. It is hard to try
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  Speaker 1: to estimate how much additional radiation is being absorbed by
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  Speaker 1: human beings out of these man made sources. Fallout is
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  Speaker 1: not uniformly spread over the Earth, but as higher in
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  Speaker 1: those latitudes where nuclear bombs have been most frequently tested.
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  Speaker 1: Then too, people in industries and research who are involved
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  Speaker 1: with the use of radioisotopes and people in medical centers
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  Speaker 1: who constantly deal with X rays are likely to get
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  Speaker 1: more exposure than others. These adjects of modern science and
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  Speaker 1: medicine are more common and widespread and technologically advanced countries
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  Speaker 1: than elsewhere, and nuclear bombs have most often been exploded
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  Speaker 1: in just those latitudes where the advanced countries are to
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  Speaker 1: be found. Attempts have been made to work out estimates
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  Speaker 1: of this exposure. One estimate of all that a number
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  Speaker 1: of technologically advanced countries, including the United States, showed that
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  Speaker 1: an average of somewhere between zero point zero two and
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  Speaker 1: zero point one eight rim per year was absorbed as
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  Speaker 1: a result of radiations usually X rays used in medical
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  Speaker 1: diagnosis and therapy. Occupational exposure added on the average not
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  Speaker 1: more than zero point zero zero three RIM, though the
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  Speaker 1: individuals constantly exposed in the course of their work would
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  Speaker 1: naturally absorb considerably more than this overall average. On the whole,
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  Speaker 1: the highest absorption was found, as was to be expected
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  Speaker 1: in the United States. If these findings are expanded to
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  Speaker 1: cover a thirty year period, assuming the absorption will remain
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  Speaker 1: the same from year to year, it turns out that
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  Speaker 1: the average absorption of man made radiation in the nation
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  Speaker 1: studied varies from zero point six RIM to five point
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  Speaker 1: five rims per thirty years per individual. Considering the higher
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  Speaker 1: figure to be applicable to the United States, it would
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  Speaker 1: seem that man made radiation from all sources is now
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  Speaker 1: being absorbed at nearly twice the rate that natural radiation
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  Speaker 1: is to put out. Another way, Americans are just about
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  Speaker 1: tripling their radiation dosage by reason of the human activities
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  Speaker 1: that are now adding man made radiation to the natural supply.
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  Speaker 1: By far, the major part of this additional dosage is
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  Speaker 1: the result of the use of X rays in searching
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  Speaker 1: for decayed teeth, broken bones, lung lesions, swallowed objects, and
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  Speaker 1: so on. End of section eleven.