65
The external gamma-ray exposures of Table 4.1 #1 affect all of
In addition, beta rays (cesium-137 and
strontium-90) emanate from soil, but have only a limited ra e in
air and very poor penetration into the body; they might aff et the
body's surface in those regions which are closest to or are ctually
touching the ground. Shoes and clothing provide complete o almost
complete protection.
the tissues of the body.
External beta-ray dose is considered to be unimportant
basis of the following. For gamma rays, the Rongelap Islan
Island external-dose ratio is 1.7 (Table 4.1 #1. The betaratio at .007 mm depth (basal cell layer, skin) should be
n the
Eneu
y dose
approximately the same.
Therefore, by extrapolation from t ie
determinations at Eneu (Shingleton et al, 1987)
the Rongelap
basal-cell dose would be 46 mrem/y, and at 1 em depth pract cally
zero (ICRP 51, Table 26).
skin is 5 rem/y (NCRP
Since the radiation protection giide for
1987b), the skin dose is a trivial o
Ap gege tees gens *: prvanpnmeeenmpmemenspc
e.