EFFECTS OF FALLOUT RADIATION ON THE SKIN
THE SHORTER-TERM BIOLOGICAL HAZARDS OF A FALLOUT FIELD
Marshall Island experience, the extent and se-
verity of the skin lesions were directly related
to the amount of visible fallout and on Utirik,
the least. contaminated island of the inhabited
group no fallout was visible andno bets lesions
of the skin developed.
The particulate nature of the material produces spotty distribution on the body. The
Marshallese claimed that the material adhered
closely to the skin and was difficult to brush
off. This was borne out by the difficulties of
complete decontamination.
Areas of the body
where perspiration is greater such as the neck
folds, axillae, antecubital fossae etc. caused
the material to stick and lesions were more
predominant in these areas.
The hair tended
to collect, the material also, particularly in
view of the cocoanut oil hair dressing used by
these people, which made decontamination
extremely difficult. Clothing, even a single
layer of cotton material, afforded almost complete protection as evidenced by the fact that
alinost all of the skin lesions developed on
exposed parts of the body. The loose clothing
warn would not have accounted for more than
about a 25 percent attenuation of the radiation
so that the protection must have been due in
part to the fact thattheloosely fitted clothing
tended to hold the radioactive material away
from the skin. It is also possible that the
material did not stick to the clothing as well
as to the skin.
There are certain biological factors known to
influence the sensitivity of the skin to radiation.
In addition to species differences, it is known
that the skin of certain parts of the body is
more sensitive than that of others. In general
the thinner-skinned flexor surfaces of the body
are more sensitive than the thicker-skinned
extensor surfaces [16].
This was found to be
true in the Marshallese since lesions were more
prevalent on the front and sides of the neck,
axilla and antecubital fossae. Another factor
is associated with pigmentation of the skin,
to be less sensitive to radiation than blends or
fallout is an exceedingly complicated problem
people with ruddy complexions [17]. A factor
which was pointed outearlier is that areas of
the body where perspiration is more profuse
cause the fallout to collect resulting in greater
and I will leave the main discussion of the subject to other speakers. The degree of skin
Sources of radiation ta the skin.- Damage to
the skin results largely from the beta com-
the energies of the beta particles of the componentisotopes. Thus soft radiation confined
reaction and damage is more dependent on the
skin effects.
depth dose than on the surface dose of beta
radiation and the depth dose is dependent on
ponent of the fallout in view of the fact that
the beta-gammaratio is quite high, All of the
largely to the dead horny Jayer and upper
epidermis would be relatively ineffective in
energy of the beta particles entering the skin
tion and particulate nature of the fallout in
producing a reactionin the skin; more energetic
radiation, penetrating through the epidermis,
could result in transepidermal necrosis; and
deeper penetration into the dermis could result,
in more severe ulcerating Jesions. Each radioisotope has its own characteristic spectrum of
energies with a maximum energy, but since
relatively few particles are of this energy, the
average energy, which is roughly one-third of
the maximum energyand the 50 percent atten-
sources on the skin, By far the greatest
part of the skin dose comes from this source.
mating skineffects.
Figure 1 shows roughly the 50 percent atten-
is absorbed in the skin. Soft gamma rays
accounts for some of the radiation dose to the
skin, and the harder gamma rays contribute
least since they are more penetrating. The
skin dose results from two sources of beta
radiation, the fallout material in direct contact
with the skin and the material on the ground.
1. Contact source.—The spotty distribu-
137
Estimation of beta doses to the skin from
FepDermis
POERMIS
g
the occurrenceof fallout would have to be visible
to result. in such damage. Forexample, in the
Darker-skinned people, brunettes, are known
3
It seems likely that
50% ATTENUATION IN SKIN (MICRONS)
186
sufficiently concentrated.
900
1060;
L
L
Ot
02
1
1
1
as
of
os
BETA ENERGY (ove)
4
J
os
Or
Figure 1-40 percent attenuation in skin (microns),
old reaction (erythema, epidermal atrophy) are
fairly dependent on the energy of the beta
particles of the various isotopes.
Thus it takes
uation in tissue are more micaningful in esti-
20,000-30,000 rep from S® (average energy 0.1
Mev.) to producea reaction while it only takes
1500-2000 rep of Sr®-Y" or Y" (average
Radiation is largely from the skin surface.
However, the possibility must be considered
uation in skin of several isotopes. With the
same surface dose the more energetic beta
reaction. It is of interest that Moritz and
Henriques found that the dose at 0.09 mm.
tion into the dermal region via the hair
greater damage to the skin.
Table 1 is made up of data from animal
studies from several investigators and shows
the energy dependence of betas from various
contact with skin results in multiple point
that a certain amount of percutaneous absorption may take place and some penctrashafts,
occur.
sebaceous and sweat glands may
The Castle fallout contained about
10 percent water soluble fission products, some
of which might conceivebly have been absorbed percutaneously. Whitten et al. [18]
have shown that thorium-x applied to the
skin results in some percutaneous absorption
and entry into the hair shafts and glands.
Weintend to investigate this problem with
fission products on the skin by means
of autoradiography.
2. Ground source-—A certain amount of
the skin dose mayresult from beta radiation
from the fallout material on the ground.
This contribution is likely to be far less than
that from the contact source. The lower
parts of the body will receive the greater
part of this radiation since the beta particles
are completely stopped in 2 meters of air.
emmiting isotopes
will
naturally result
in
isotopes in producing recognizable skin reac-
tions.
Note that the surface doses for thresh-
energy 0.5-0.6 Mev.) to produce the same
depth of the pigskin (estimated to be the
epidermal
thickness)
was
constant
within
several hundred rep to produce transepidermal
injury [15]. Wilhelmy has also noted thatit
takes roughly the same dose of electrons and
soft X-rays at the level of the subpapillary
layer to produce erythema[19]. On this basis
Taste 1—SURFACE DOSE REQUIRED TO PRODUCE RECOGNIZABLE EPIDERMAL INJURY
Investigator
Henshaw,et al_ow. 02
* Snider and Raper.
Raper and Barnes... ...- .
ee
L -
Lushbaugh. ...22-..200. 0.02.
Moritz and Henriques .
Antmsi
eee
Tsotope
pe
pa
pa
se
se
Co®
Cg?
Srve
os
ye
Average en.
eray (Mov)
0. 5
-5
-6
3
- 05
al
12
3
5
-7
Surface doso (rep)
1, 500-4,
2,
5,
2, 500-5,
20, 000-30,
4, 000-5,
2, 000-3,
1, 500-2,
1, 500-2,
1, 500-2,
000
500
000
000
060
000
000
000
000
000