oho.
A more refined analysis of the above data [Gh] allowed the conclusion
that all genotypes exhibited a radiation induced life-shortening effect depending on a single common primary injury parameter.
For acute single-dose
exposures the parameter could be expressed by the number of days of life lost/
unit dose, equalling 0.28 days/R.
This parameter could be combined with others
to give equations predicting the life-shortening for any combination of normal
life expectancy, dose, incidence of neoplastic conditions.
After correction
for leukaemia and ovarian tumour induction, life-shortening for both sexes following exposure to 570 R was 111 days and exposure to the same LD
@ constant proportion of life lost amounting to 19 per cent.
caused
In aoretion-of-
life experiments mean survival time and mean accumulated dose varied directly
with control survival and therefore at each exposure-rate strains having different control survival lost the same proportion of their life expectancy.
With a few exceptions, the mean accumulated dose and the acute LD
50/30
were
shown to be correlated to each other in that each had a common relationship to
the normal life-span.
aut.
Gowen and Stadler [G11] published also a large series of experiments
where ten different mouse strains (four pairs for each genotype) were initially exposed from mating to death to 6005 gamma-irradiation (0.6 to 2.7 R/
day) for 22 hours/day.
The design and the analysis of this research, although
involving irradiation for the duration-of-life, was centered more on the capacity of irradiation to stop the reproductive functions of these mice, than to
shorten their life-span.
eke.
Other analysis by the Argonne group [S5, G9] contain comparisons of the
relative life-shortening effect of
°C irradiation to death in genetically dif-
ferent mouse strains and indicate the constancy of the slope of the relationship
expressing the log mean after-survival against exposure-rate.
The linearity of
this relationship over the exposure rate range between zero and 56 R/day was es-
tablished for BCF1, C57BL/6, Balb/c and A/Jax male and female mice [S5], thus
confirming previous findings with the LAF1 mouse [S84].
The control survival of
the male and female mice of the four genotypes cited (8 groups in total) ranged
from 466 to 796 days and these differences in life-span curves were nearly parallel and were displaced from one another by the same amount of displacement
of the control survival times.