B. L. LARSON AND K. E. EBNER
is quite small (see Table 6), at present the greatest debate over the continuation
of nuclear tests centers around the genetic effects this increased radiation may
have on future generations. These effects are extremely difficult to evaluate since
so little is known about human genetics. Judging from experience with plants,
insects, animals, and other lower organisms, there is every reason to expect some
genetic effects of radiation. It seems likely that a major portion of the spontaneous mutations of the human species is not due toradiation but to other causes.
Muller [quoted by Libby (74)] has estimated that 10% of the spontaneous mutations in the human species may be dueto irradiation. If one estimates that the
150 (mr) per year from natural radiation now causes 10% of the spontaneous
mutations, then the test fallout, if continued indefinitely at the present level
would cause an increase in the over-all natural spontaneous mutation rate of
about 0.2% (14). This effect is comparable to moving to a slightly different
locality and is much less serious than changing houses or doing any one of a
dozen different things (74).
At present in the United States some 80,000, or 2%, of the four million
children born alive each year have some tangible genetic defects (2). The increase expected, if estimates and extrapolations to low levels are justified and the
tests continue, would be about 160 children per year at the 0.2% level (2).
Whether this effect can be considered small compared to unavoidable damage
caused by spontaneous mutations and other presently accepted hazards of life
depends on ethical and emotional differences in individuals. We as a country
accept death and maiming through preventable accidents such as those from jobs,
sports, automobiles, ete. We discount the harm by considering the advantages.
Also, the individual believes he can exercise some control over them. The fallout
hazards are beyond the control of the individual, involve his descendants, and
so have a strong emotional impact. The need for further controlled studies in
this area is apparent. From the evidence at hand, one must conclude that the
present and projected increases in radiation due to nuclear detonations, if testing is continued at the same rate, are small enough so that they should not cause
us undue concern until further facts concerning humansare available.
APPENDIX
Common Radioactive Terms
1. Curie (ce): The absolute unit of radioactivity equal to 3.7 X 101° disintegrations per second. The microcurie (ye) is equal to 3.7 X 10+ dps. (4).
2. a-Particles: Nuclei of helium atoms with high ionization power but low penetrating power.
B-Particles: Electrons traveling at high velocities with better penetrating but
less ionization power than a-rays.
y-Rays: Light or x-rays with high penetrating power and comparable biologically to 8-rays in ionization power.
3. Roentgen (rj): A quantity of radiation such that the associated corpuscular
emission per 0.001293 g. of air produces, in air, ions carrying one electrostatic
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