8000 rep will cause blistering of the skin and temporary loss of hair.
Healing of ionizing rediation burns will be somewhat slower than from
thermal burns, but will probably be complete with no undue increase in
numbers of secondary infections.
12,000 to 14,000 rep will cause deep
blistering followed by permanent scarring.
Until further work is re-
ported, it appears that a value of 2000 rep should be considered the
threshold dose for skin burns; however, on the skin of the hands, where
there is increased thickness of palmar cornified tissue, protection
against up to 3000 to 5000 rep air dose would be provided by the cornified layer as quoted by NavMed P-1350.
The biological effect of beta radiation delivered to the whole
body may be considered to vary directly with the dose rate within
limits defined by a recovery rate and a non-recoverable fraction of the
total dose.
Estimates of the mid-lethal dose of whole body beta radi-
ation are widely variant and cannot be entirely resolved.
For example,
it has been found by Zirkle, et al. ,26/ that in comparing the IDs9 of
baby rats, mice, grown rats, guinea pigs, and rabbits, the log of the
gram rep absorbed, i.e., the total energy absorbed by the animal,
varies directly and linearly with the logarithm of the weight of the
animal.
This suggests that body volume as well as surface area involved
are determining factors in the degree of mortality produced.
If a toxic
substance liberated by damaged tissue cells plays e role in lethality,
it would be consistent with the observed data in that, as the body volume to skin surface ratio increased, the toxic material per wit body
volume would decrease.
Thus, if this experimentally determined rela-
tionship of body size is extrapolated to man, a dose of the order of
40,000 beta rep is obtained as IDs for man.
On the other hand, a
fairly sound assumption can be made that a dose causing a moderate
degree of local skin damage, if applied to the entire body, will result
in death in at least a moderate percentage of those involved.
This
26/ Zirkle, R.E., Biological Effects of External Beta Radiation,
National Nuclear Energy Series, Div. IV, Vol., XXII, E., 1951.
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