no significant losses from the
skeleton wWere reported during
a 250 q
bored nichchee eased absorp
tion of actinides has been
reported when adeings
ating agents or citrate comple
xes.
.
The
percen
tage
wren tay Administered Pu absorb
ed in the GI tract of rats ineres
eed 700 fen
when a . nistered with DTPA
Plus citrate (1.7% of administered
dose)
when
coeeare ans absorption of Pu
nitrate (0.0011%) (Baxter and
Sullivan, 1972)
rt increaving anon admini
stered separately, were slight
ly less ef fective
rption,
0.
and 0,79% of absorbed dose
res
ti
(gee retention was highes
t with citrate (0.091%), "pallo
u ef a)”
o ) also reported that neptun
ium citrate was more readily
absorbed than N
nagnitede that Np absorption
in the gut was higher than Pu
by an order of .
+
Scott et al. (1949), using 24lanci
3
and
242
(mCl3,
estimat
and 0.05%, respectively, were
absorbed in the GI tract.
Comparablevalues
were Teported using
BkCl3 and *53BkC14 (Hungate et al.,
1972),
Elevated GI
Buldakovet af.(1970) ne animal
s has been emphasized by severa
l investigators
.
reported high absorption and
skel
tal
young dogs. Ballou (1958) and
Baxter and Sul li
) eatimated chac
absorption in young rats was from
2 to 100 ti
times
aeBre
greate
atee
r then
th
ree
f
gtat Pu
Moskalev et al. . (1969) re ported
on the effects of continuousi
aly y feeding 23
2 39
parate ro rats from age 3 months
till death.
The skeleton burden was always
mes the liver burden with the
result that 5 of 68 rats develo
osteosarcomas with an estimated
ed
average bone dose of 57 rads
P
et crac eenee Eeeeundant
literature that absorption of
actinides from the
€
bloodstream is almost insignific
ant und er most conditi
.
Potential hazards may exist, howev
er, if actinides are present with
complexing
oxPoee
or chelat
d. ing agents
g
, . if a bsorption is continuous,
or
if young animals are
Avatlable literature indicates
that the epidermis of smal] mamma
ls is an
. ective parrter fo the absorp
tion of transuranics, particular
ly the insoluble
nompound most ; ely to be found
in the environment.
Increased absorption
(Oakley andThompson,1955;BuldakorofarnsopubLity of plutonium compou
nds
high levels of absorption and
retention have been repo tedwi
ch
dewey
(992) and intramuscular admin
istrations (ICRP, 1992; Durbin”
9) fee
a nas Co puncture wounds ceee
eussand intramuscular injection,
which may
Sustained under natural condit
i
cane ekereeeePresent Plutonium
uptake routes most likely co resul
t ie etenticent
. on burdens. Langham et al,,
1962, reported no systematic absorp
tion
Plutonium oxide when it was applie
d to abraded skin of rabbits
Wh
solution of PuCl3 in dimethyl sulfox
ide was placed on the naked sole
of a.
oe foots 0.26% of the appli
ed dose was detected in the circu
lating blood
wath n3 rr] ures (Watters and
Johnson, 1970),
Khodyreva (1968) applied Plutorate (pHs) to the skin of rabbit
s and estimated 0.15% was absor
bed
and
retained after 14 days. Hungate
et al. (1972) found that 0.03% per
om? of “
einsteinium was absorbed when 0.01
N nitric acid was applied to naked
rat
skin, A maximum of 1.2% of Pluto
nium metal implanted subcutaneously
1
bbi
and mice was absorbed and distribute
d throughout the body durin lifett
:
(Lisko and Kisileleski, 1953).
In their studies, the liver/skeleton
u
tak
ratios were dissimilar between the
two species, probably reflecting the
rapid
388
liver clearance rate reported in numerous studies of the rat.
The average rat
skeleton contained almost 10 times more plutonium than the average rabbit
skeleton. Osteogenic sarcoma of the spine was reported from the rat with the
highest burden.
The results of their data indicate the desirability of obtaining more information on plutonium, and other transuranics, uptake in numerous
species of animals. Weeks and Oakley (1953, 1954) reported plutonium absorption
as high as 2% with 10 N nitric acid and 0.3% with 0.1 N nitric acid after 5
days. Oakley and Thompson (1955) reported increases in absorption with an
increase in depth of administration.
Using Pu (NO3), with 0.1 N nitric acid,
an increase in percentage of administered dose absorbed from 0.33% in intact
skin to 2.7% from subcutaneous injection with a corresponding increase in
liver deposition was reported.
Cable et al. (1962) estimated up to 12% retention in the lymph nodes and 4.8% in bones after 7 days when Pu (NO4), was
injected intradermally. Their data indicated that percent absorption may be
inversely related to dosage as Thompson (1967) later suggested.
Scott et al.
(1948) and Taylor (1969) have reported absorption values of 65 and 51% of
Pu0yClo and plutonium nitrate, respectively; 256 days after administration of
Pud.Cly 47% was retained in the skeleton.
Whereas rather low levels of uptake of transuranics by means of ingestion or
parenteral absorption into vertebrate systems may be important particularly in
chronic situations, laboratory experiments indicate that inhalation is the
most hazardous natural route of entry.
Inhaled insoluble Pu produced Lung
tumors (Moskalev, 1972; Bair and Thompson, 1974).
Significant increases in
lung tumors of rats were reported with accumulated dceses of 50 rads using
inhaled 77%pu citrate (Moskalev, 1972) and 9-32 rads with soluble *38py (Sanders,
1973).
Several works provide summaries of inhalation studies relating to the
retention, translocation, and biological effects of Pu and in some cases other
transuranics (Abrams ¢t al., 1947; Bair and Willard, 1963; Morrow, 1966;
Buldakov, 1970; Sanders, 1973; ICRP, 1972; Bair et al., 1973 and others).
The
results of these studies indicate that absorption from the lung varies from
Absorption, fate, and effects of inhaled
less than 1% to as much as 10 to 15%.
transuranics depend on such factors as solubility, chemical form, respiratory
rate, and particle size.
In addition, Bair et al. (1966) and Buldakov et al.
(1970) have pointed out important
differences between acute versus chronic
Insoluble Pu compounds
are retained
exposures.
(239pu 0.)
in the lung and associated
lymph nodes and are translocated to the bone and liver very slowly, where they
are retained; hence, resulting pathologies are somewhat confined to these
tissues,
Soluble Pu compounds are translocated relatively rapidly via the
blood to bone and liver and, to a lesser extent, lymph nodes, kidney, spleen,
and gonads.
Translocation rates and retention times differ between some
species as rats loose Pu from liver much more rapidly than dogs. Stannard and
Morrow (1956) demonstrated the importance of respiratory rate and volume to Pu
deposition.
Bair and Willard (1963) {ndicated that deposition and retention
of Pu was greatest when inhaled as large particles of 0.6 uw CMD.
Inhaled Pu
Q2 and more soluble Pu compounds result in lymphopenta.
Bafr et al. (1966)
reported all but two dogs with less than 0.003-0.0002 wCi/g Pu O59 in lung
showed persistent lymphopenia and leukopenia throughout their life span.
Bair
et al. (1973) reported there is a possible relationship between Pu-induced
lymphopenia, lymp node pathology, decreased immunological capability (Dilley,
1970), and the pathogenesis of Pu-induced pulmonary neoplasia.
389