Til.
DEVELOPMENTS IN RADIOBIOLOGICAL RESEARCH
Radiobfological research on internally deposited fission products under-
went a number of evoluttonary changes fran the 1940s to the present.
These
changes occurred in investigations on the health effects of these radionuclides and in attempts to estimate the risks that accanpany irradiation.
Studies on the environmental significance of radionuclides also changed, as
-- prompted by the recognition of fission products fn fallout as unwelcome
companions of the testing of nuclear weapons.
Health Effects
Studies on the biological effects of internal emitters general ly
progressed from an initial production of radionuc! ides to metabolic studies on
their distribution and excretion.
Fran here, studies on the acute toxicity,
elicited by exposures to large amcunts of radioactivity, were next.
Then,
since most of the concern was for protection of the worker, chronic studies
involving long-term exposures to lower levels of radioactivity were done to
gain understanding about the late effects that might be produced. The prior
experience with the late effects seen in the radium dial patnters prompted
long-term studies with other radionuclides in the 1940s, principally with bone
seekers such as strontfium-89, -90, and plutonium-239.
In depth studies of
these radionuclides began tn the 1950s, when the Atomic Energy Commission
established several! beagle dog colonies around the country.
Work continues to
the present time.
For radiofodine, the pattern of research development in the 140s was
general ly the same, though for a long time {t renafned fixed in the acute
effects phase, since this was the desired end-potnt for the treatment of
thyroid disorders.
Only after the thyrold gland was strwn to be relatively