hina biak
fruit flies.
Only later did the stochastic nature (e.g., Cancer) of the
response of somatic tissue to radiation become clear.
Repairable Injury
(e.g. On Spermatogenesis, leukocyte counts) was a functional phenanena and
{rreparadle injury was an “accleration of aging” phenomenon that shortened
lifespan.
With late effects such as bone cancers, the all-or-none principle
In experiments with
groups of animals exposed to graded dosages of bone seekers, differences th
numbers of cases of cancer and their times of occurrence were observed.
Higher doses resulted {n more tumors at earlier times than lower doses, Low
enough doses did not result in effects before animals dfed of natura) causes
ec
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epan
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described above became the al}, none, or some principle.
(Brues et al., 1947; Brues, 1949), thus leading to the concept of a "practical
threshold” (Evans et al., 1972).
The shape of the dose-response curve for radiation-induced cancers became
the subject of debate in the 1950s.
Several scientists (Lewis, 1957; Court-
Brown, 1958) espoused linearity as the proper way to express the relationship
of dose and effect, citing a proportional increase in effect with increasing
dose in irradtated human populations as evidence for their claim.
Others
(Mole, 1958, Finkel, 1958; Brues, 1958), who based their opinions more on
ae
.
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‘animal data, considered a curvilinear dose-response relationship to be mre
appropriate.
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.
.
mite tachetlieaters
The debate over the proper shape of the dose-response curve has continued
to this time.
report of the Canmittee on the Biological Effects of lonizing Radiation (NAS,
r
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.
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.
1980),
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This was demonstrated by the recent and controversy-ridden