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TUNNARD
TONICOLOGY OF RADIONUCTIDES
tee kere Dee lae dag
“vases. Also a dose-effect relationship( stated
so wank body burden or calculated dos
e) dic
coms were largely breaks(5.86 per hoa
dred
hone BAH Mot deletions or rings. The rela
tionwf chsdacnee Is, of course, sl in the spec
ula-
divlure that ihe mammoch scientific
and
~
“aurents will be soived in time to
make this
“sme of the cthers but it is hone
d that the
AE eaeik,
ie ental
mcidenits of cadcer in man trom
the deposicturh there have been some depo
sitions in
stodets largely the effectiveness
of contral
vely short Ume during which
these low body
“ts, because of the importance
ef plutonium
ale animal studies have been
underway
va nied considerably since the
early and midfm man extending over man
y years. These
wf reinterpreted (76),
= eral milestones have been
passed in the
yand Mays et al (4), report
that the chief
sclony exposed to one of sevet
7
a] boneaa?
“Ra (mesothorium , 7?8Ta, and
2S
is
wah osteesarcoma 8 vear
s after injection of
4 bs likely ton an activity
basis) as for
as exceeded only by that for
228Tp.
+ ht bins fitneicg, and
all Studies reiterate
tel di erence in toxi
city between pluto4 ark wth rodonzs
(80, 81), This empirica
l]
es uiag of maximum
allowable exposures
In an independent study on inhaled aerosols of 77°Pu and 73%Pu in the dog,
Yuile, Gibb & Morrow(90) report increasing pulmonary pathology, typical of
radiation effects, from about 1500-2000 rads to 15,000 rads. They do not,
however, report frank pulmonary carcinoma.
Damage to accessory pulmonary structures, especially pulmonary Ivmph
nodes, is commonly seen, especially if the compound inhaled !s insoluble and is
cleared from the lungs primarily by nonsolubilization processes. With plutcn.um
axide, maior ceeumulations occur m1 tracheebroncival-lyiigh nodes: 20-100
umes the concentration in lung. Fibrosis. scarring, and loss of bh mphatic aadutes
are common, but frank neoplasia ov hese structures has wot lo ound shower.
{9} reports chat iwo dogs and several rais that mhaled “selikic 7 nletoansys
developed matignant lymphoma, and Leber et al (92) report ivmipaomia ai die
regional lymph nodes of a dog receiving sir-oxidized pluteniim $7 sivoutsnecus
cad to radium as a
volume
sane ee
Aa
TA. deposits oF pluton
ium
. sod sad han This has
ted Nave (8-4) to
Teel Clinger With Par
enicre tly injected
fey
RE
Sh traysPOER
UooET
. A :LM
v S A D Sie
2 7 oe
RETBRIER
.
PlulomuM dtu Lu We Comeiustoni Uidl alc disk ls AOU CQL ee Uist:
depends on the rewte ef entry. Hence the relative risk will also vary with ¢ 2
diode of administration and this conclusian cannon bo extended te plusonar >
enlerng OF reutes Cloer Li dgeenon,
The mean skeletal rad dese at the lowest level showing ostcusarecemuato daic
is 78 rads at ] year before death, @6@ rads ut the time ot ceath and the years
hetween injection and death: 9.92 (79). If we campare these to the numbers seen
in other avimals gerd mon for 7°°Ra the empirical toxicity ratie of slightly above
5 anpears to be fully confirmed tn this ‘arge experiment.
Recent work also makes possible coranarison of the effective doses for cstecsarcoma in rodents to those in beagles. Buldakov & Lyubcranski (85) summarized work with 2208 rats recetving niutonium 239 at about 3 months or age.
Incidence rates of about 3°) are seer at averege caiculated skeletal doses af
from. 25-76 rads depending on rouie of entry and cormpound. Mays (personal
communication) calculates the lifetime risk of bone sarcoma in this experiment
as 0.06°4 per rad. But this may not be a smooth function, as many grouns at
low doses showed no ostecsarcomas.
The data of Finkel & Biskis (86) using CFI female mice showas calculated by
Mays & Lioyd (79) 3.994 incidence at 40 rads dose accumulated up to 140 days
before death. This is less than 0.194 incidence per rad. Neither of these rates are
markedly different from those for the dog, e.g. 0.37%, per rad at estimated start
of tumor growth or perhaps lower. Since this figure is for monomeric piutoniun:
{see pace 336), which maybe about twice as carcinogenic as the polymeric form,
the difference among the species becomes even less signiticant. This relative
confluence lends credence to extrapolation to man and the expectation that the
carcinogenicity of plutonium in the bones of man may well be a factor of 5 ar
more greater than thai of radium. Thisis the figure currently used in assaying
hazards oy man. Lloyd & Marshall (87) suggest that the relative eMectiven.ss
factor may be higher in man than in dog because of cifferences in bone struciure
The development of lung cancer in animals inhaling aerosols of plutonium
has nowbeen fully documented (19. &8. 89).
STE SOT Ussue.
Whhe scunewhat
oY
“ee2 Tamers af ce TSSke,
e.g
Le, Cg,
2 ietaps
335
and the higher rate of burial of surface deposits of *7°Pu in the dog.
“'Prrence hive now bee
n all but settled as
oo cuthdes in bone (4,
77, 81, 83, and many
Ls on bone Surfaces,
whereas radium
' tees With caleiu
:n and deposits
rotys ‘ugh sill not uni
formly). This has
“wah ae
“ser
Sete
“eesiar velacialan ad aten Sem tana tos. LO mebapaeaied teete an dads ae ead cual dies “jon vealed gee adh deve « Bones
~s Re
foot
~ Peatint
aeae
Se Pee MENT
¥r g bree
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