-17radiation, the effects are classified as somatic or genetic.
Somatic cells are those concerned with the maintenance and
integrity of the individual and include cells in the bone
marrow, blood,
liver or nervous system; genetic cells are
the reproductive cells of the gonads,
which are responsible
for the transfer of genetic information from generation to
generation.
Damage to somatic and genetic celis differs in
that somatic effects are limited to the irradiated individual, whereas genetic effects may be passed on to the
progeny
of the irradiated individual.
The biological effects of radiation vary consider-
ably between individuals of the same species but the
difference between widely separated groups of organisms
is even greater.
In general the more complex the organism,
the more vulnerable it is.
The lethal dose,
fifty per
cent at thirty days (LD59), is about 400 roentgens for man
but is two to three times greater for fish.
Values for
other organisms are given in Figure 1 which is prepared
from data reported by Donaldson and Foster (1957).
Owing
to the great variety of circumstances that existed in the
experiments from which these data were obtained,
the values
‘in Figure 1 represent only orders of magnitude of effects.