-6of these radioisotopes of todine is short (range from 2
hours to 8 days), the damage to the thyroids would be
expected to occur soon after exposure.
Because the genetic effects of lonizing radiations
occur in the progeny of the exposed individuals and may be
subtle,
it cannot be said that mutations have not occurred
in the fish in the Bikini-Eniwetok area,
although it can
be said that there have been no recognizable mutations in
the thousands of fish that have been observed.
If muta-
tions have occurred they are not the type that manifest
themselves as morphological abnormalities.
Laboratory
experiments rather than field observations are needed to
determine the genetic effects of low,
chronic doses of
ionizing radiation.
In the above discussion it has been pointed out
that the indirect effect upon man of the uptake by fish of
radioisotopes from the sea is of greater concern than the
direct effect upon the fish themselves.
presentation to follow,
Therefore,
in the
principal consideration will be
given to the role of fish in transferring radioisotopes
from the sea to man.
Because fish acquire radioisotopes
either directly from the water,
or indirectly by feeding