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011 - Background Radiation · Percheron horse

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  Speaker 1: Section ten of the Genetic Effects of radiation. This is
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  Speaker 1: Red by Yoganum. The Genetic Effects of Radiation by Isaac
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  Speaker 1: Asimo and Theodosius Dobzanski. Section ten. Background radiation ionizing radiation
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  Speaker 1: in low intensities is part of our natural environment. Such
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  Speaker 1: natural variations referred to as background radiation. Part of it
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  Speaker 1: arises from certain constituents of the soil. Atoms of the
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  Speaker 1: heavy metals uranium and thorium are constantly, though very slowly
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  Speaker 1: breaking down and in the process giving of alpha race,
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  Speaker 1: beta rays, and gamma race. These elements, where not among
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  Speaker 1: the most common, are very widely spread. Minerals containing small
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  Speaker 1: quantities of uranium and thorium are to be found nearly everywhere.
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  Speaker 1: In addition, all the Earth is bombarded with cosmic waves
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  Speaker 1: from outer space and with streams of eye energy particles
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  Speaker 1: from the Sun. Various units can be used to measure
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  Speaker 1: the intensity of this background variation. Ron gen abbreviated small
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  Speaker 1: R and named in honor of the discoverer of X
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  Speaker 1: rays willem ron gen is a unit based on the
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  Speaker 1: number of ions produced by variation. Rather more convenient is
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  Speaker 1: another unit that has come more recently into prominence. This
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  Speaker 1: is the rad an abbreviation for radiation absorbed dose. That
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  Speaker 1: is a measure of the amount of energy delivered to
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  Speaker 1: the body upon the absorption of a particular dose of
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  Speaker 1: ionizing variation. One rad is very nearly equal to one
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  Speaker 1: ron gen. Since background vardiation is undoubtedly one of the
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  Speaker 1: factors in producing spontaneous mutations, it is of interest to
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  Speaker 1: try to determine how much radiation a man or woman
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  Speaker 1: will have absorbed from the time he is first conceived
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  Speaker 1: to the time he conceives his own children. The average
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  Speaker 1: length of time between generations is taken to be about
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  Speaker 1: thirty years, so we can best express absorption of background
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  Speaker 1: variation in units of rats per thirty years. The intensity
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  Speaker 1: of background radiation varies from place to place on the
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  Speaker 1: Earth for several reasons. Cosmic rays are deflected somewhat towards
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  Speaker 1: the magnetic poles by the Earth's magnetic field. They are
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  Speaker 1: also absorbed by the atmosphere to some extent. For this reason,
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  Speaker 1: people living in ecuatorial regions are less exposed to cosmic
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  Speaker 1: rays than those in polar regions, and those in the
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  Speaker 1: plains with a greater thickness of atmosphere above them are
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  Speaker 1: less exposed than those on high plateaus. Then two, radiactive
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  Speaker 1: minerals may be spread widely, but they are not spread evenly.
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  Speaker 1: Where they are concentrated to a greater extent than usual,
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  Speaker 1: background radiation is abnormally high. Thus, an inhabitant of Harrisburg, Pennsylvania,
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  Speaker 1: may absorb two point six four rats per thirty years,
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  Speaker 1: while one of Denver, Colorado, a mile high at the
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  Speaker 1: foot of the Rockies, may absorb five point zero four
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  Speaker 1: rats per thirty years. Greater extremes are encountered at such
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  Speaker 1: places as Kerala, India, where nearby soil rich and thorium
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  Speaker 1: minerals so increases the intensity of background radiation that as
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  Speaker 1: much as as eighty four rats may be absorbed in
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  Speaker 1: thirty years. In addition to a high energy variation from
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  Speaker 1: the outside, there are sources within the body itself. Some
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  Speaker 1: of the potassium and carbon atoms of a body are
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  Speaker 1: inevitably radioactive as much as point fire rat, but thirty
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  Speaker 1: ers arises from this source. Rats and rong gens are
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  Speaker 1: not completely satisfactory units in estimating the biological effects of variation.
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  Speaker 1: Some types of radiation, those made up of comparatively large particles,
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  Speaker 1: for instance, are more effective in producing ions and bring
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  Speaker 1: about molecular changes with greater ease than do electromagnetic variation
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  Speaker 1: delivering equal energy to the body. Thus, if one rad
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  Speaker 1: of alpha particles is absorbed by the body, ten to
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  Speaker 1: twenty times as much biological effect is produced as there
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  Speaker 1: would be in the absorption of one grad of X rays,
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  Speaker 1: gamma race a beta particles. Sometimes, then when speaks of
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  Speaker 1: the relative biological effectiveness are bee of radiation or the
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  Speaker 1: Orongeen equivalent man rim rat of X rays, gamma race
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  Speaker 1: or beta particles as a rim of one, while a
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  Speaker 1: rade up alpha particles as a rem of ten to twenty.
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  Speaker 1: If we allow for the effect of the larger particles,
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  Speaker 1: which are not very common in ordinary conditions, we can
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  Speaker 1: estimate that the gonads of the average human being receive
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  Speaker 1: a total dose of natural radiation of about three rems
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  Speaker 1: for thirty years. This is just about an irreducible minimum.
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  Speaker 1: The end of section ten. Background variation