It is unrealistic to suppose that all sources of man-made radiation
should be abolished. The good they do now, the greater good they will do
in the future, cannot be abandoned. It is, however, reasonable to expect
that the present Nuclear Test Ban Treaty will continue and that nations,
such as France and China, which have nuclear capabilities but are not
signatories of the Treaty will eventually sign. It is also reasonable to
expect that X ray diagnosis and therapy will be carried on with the
greatest circumspection, and that the use of radiation in industry and
research will be carried on with great care and with the use of ample
shielding.
[Illustration: _A film badge (left) and a personal radiation monitor
(right) record the amount of radiation absorbed by the wearer. These
safety devices, worn by persons working in radiation environments, are
designed to keep a constant check on each individual’s absorbed dose and
to prevent overexposure._]
As long as man-made radiation exists, there will be some absorption of
it by human beings. The advantages of its use in our modern society are
such that we must be prepared to pay some price. This is not a matter of
callousness. We have come to depend a great deal for comfort and even
for extended life, upon the achievements of our technology, and any
serious crippling of that technology will cost us lives. An attempt must
be made to balance the values of radiation against its dangers; we must
balance lives against lives. This involves hard judgments.
Those working under conditions of greatest radiation risk—in atomic
research, in industrial plants using isotopes, and so on—can be allowed
to set relatively high limits for total radiation dosages and dose rates
that they may absorb (with time) with reasonable safety, but such rates
will never do for the population generally. A relative few can
voluntarily endure risks, both somatic and genetic, that we cannot
sanely expect of mankind as a whole.[9]
From fruit fly experiments it would seem that a total exposure of 30 to
100 rads of radiation will double the spontaneous mutation rate. So much
radiation and such a doubling of the rate would be considered
intolerable for humanity.
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.