Nene ne ee TTT coe nerenee nearregres ante ammar eo cant
e@n-?
Even though most of the retained burden fn mice and rats was in the
skeleton, the tote! amount retained in the body was small (Tannenbaum et a!.,
1951).
Less than 30 percent of the Injected quantity of uranfum renained in
the body 1-2 munths after the injection of non-toxic quantities,
injected quantity of uranium was at a higher, toxic level, as much as 40
percent was retained.
The destructive effects of uranium on the kidney
(Barnett and Metcalf, 1949) were responsible for the altered pattern of
uranium excretion in the latter group.
The toxicity of uranium compounds was studied in a number of animal
species during the 1940s and later.
Ameena antetee rene
When the
Administration of uranium was by
ingestion and inhalation as well as by other modes of exposure, and the
duration of individual studies ranged fram one month to two years (Voegtlin
and Hodge, 1949 and 1953).
The significant target of natural uranium toxicity is the kidney.
Even
ee eee
though there {fs long tenn retention of uranium by bone, administration of
sufficient uranium to result fn radiation effects would be difficult.
because dosages of uranium thet are even Jower than whe
This fs
{s required to
produce skeletal effects would still be high enough to lead to toxic, fatal
effects on the kidney (Bernard, 1958}.
It is the 4.5 x 10-9 yr half-life
and the low specific ectivity of uranium-238 (about 0.3 microcuries per gram)
that limit the amount of radioactivity that can he incorporated in the body.
Even when natural uranium is enriched beyond the normal 0,74 235U (half-life
© 7.0 x 108 yrs), as 1s the case for uranium based atomic weapons (e.9.,
90% 235y) and uranium reactor fuel, the low specific activity of
v2 microcuries per gram for 235% would Vim(t the radiation exposure,