-~ 61the radioactivity of whote fish does not tell what isotopes
are present or whether the radioactivity is on the outside
surface of the fish or absorbed within the tissues,
edible or non-edible.
either
Without this information there is
some question as to the necessity for discarding the fish.
At the time the fish were being monitored at dock
side, determinations of the gross beta activity of fish
tissues were made of a limited number of samples in labora-
tories.
Values as high as 48,000 cpm were obtained from a
sample of skipjack liver in June 1954 (Kawabata 1956b) but
the isotopes present were not identified.
Three months
later the count was one-sixth of the June value.
[In the
same fish the radioactivity of the muscle was 160 to 180
cpm per gram,
the highest value found for muscle.
Later,
the principal isotope in the muscle of another tuna,
an
albacore, was identified as zn©5; other radioisotopes were
present but not identified.
Since 1954 some of the results
of the analyses of fish for specific radioisotopes by
Japanese scientists have been published in English (Hiyama
1957); these are summarized in Table VII.
Other results
have been published in Japanese but are soon to be published
in English as part of a report on radioactivity in marine
organisms which is being prepared by the United Nations