(aquatic insects probably also fall in this category)
and the fish are most sensitive with an LD. 5 of about
one thousand roentgens--in the same order of magnitude as that of other cold-blooded vertebrates ~-
.. It must be recognized in any consideration of
the relative sensitivity to radiation of different
groups of organisms that considerable variability
exists between similar species.
In comparing the
sensitivity of two species of snails, Bonham and
Palumbo (1951)
found that
‘at 10 kr, approximately
one month elapsed before 50 per cent of the Radix
died, while in the case of the Thais it was approximately one-half of a year.‘
Consideration must also
be given to the different developmental stages of
the same species.
1936, Rugh,
Since many investigators
(Evans,
1949) have correlated radiosensitivity
with metabolic rate of the dividing cell,
it is not
surprising that dormant eggs of aquatic invertebrates
should be especially resistant.
(1951)
found that the two-week LD
eggs was about 50,000 roentgens,
Bonham and Palumbo
the eggs for a short time in water,
development was resumed,
for dry Artemia
50
but after soaking
so that embryonic
the radiosensitivity increased
more than twofold.
The Bikini-Eniwetok test site in the Pacific, where the
United States has tested its largest nuclear devices,
provides
the best study areas of the fate of radionuclides in the sea and
their effect upon the biota.
Because the levels of radioactivity