~ 10 -
Let us again aoply the criterion of normal human exr ciences
to this. Measurements have shown that the general & 2rage
intensity of fallout gamma rays from tests’ is 1 to % :illiroentgens per year.
Now the general magnitude of th effects
to be expected from this can be compared with the natural
radiation intensity. We find, as mentioned earlier, that
such things as living in a brick house instead of a wooden
house can amount to as much as 25 to 50 milliroentgens extra dosage per year, that there are certain areas in the
world where the average dose in this country of 150 milli-
roentgens per year is exceeded by ten-fold, that people
living on granitic rock as compared to those living on
sedimentary rock receive about 70 milliroentgens per year
more dosage due to the higher content of uranium and thorium
in these rocks and that people living at higher altitudes
have a higher natural cosmic ray dosage. Also, of course,
we know that medical uses of X-rays can be considerably
larger than any of these fallout dosages.
We do have experience and valid evidence that the
somatic effects other than cancer and leukemia, that is,
the effects of radiation on ordinary human health, require
dosages which are very much larger, of the order of £5 to
50 roentgen units in order to be observed as changes in
the blood and 100 to 200 roentgens for injury symptc: 53
whereas the dosages we are speaking of from test fallout
are about one hundred thousand fold smaller.
As for genetic effects, these are extremely
difficult to evaluate, since tnere is so little known
about human genetics. But judging from experience with
plants, insects, animals, and lower organisms, there is
every reason to expect some genetic effects of radiation.
The question is how much radiation is required for a given
level of effect. There are a certain number of mutations
in every new human generation. Are these largely induced
by natural radiation or are they mainly of chemical, or
rather biochemical origin, or both? From a chemical point
of view, it seems likely that not all the spontaneous
mutations in the human or any other species are caused by
radiation effects, because it seems likely that radiztion
acts in inducing mutations mainly via molecules which it
generates in the human cell, and that the mutations Gre
caused by these chemicals and therefore in a sense are
.