.
rg
wa
40. ‘She probic ms of high lceal concent ton
wWeterat (irantialy Gl¢
of cose ace at these moot sovere wie: rad IRCLIVS Det
Vaile
some
sol
merry Ce“ussion} de
pariteclate angie: lab bv the feo uy CU cay wile
fang
adaotiyyhaces,
ad fart Pe‘esis based
ecetrdttecs. Here the locnh Coco can reach very
on
dose
Cstecminatioa
encounters prifonad
high valucs even theugh the Incan tissue dase
ypstucel toute“s
my be very low. Gereintyii Canuat be assured “acu! Ties, onoilering onty che yey
there
is
first
the
pioblaa
of
lack
off
newledes of
thathacacny ofe sc aud efcctwill hold at these
the
sensitivity
to
radintion-induced
matizaant
Richt doses aud @os.c rates, On the ather ha:nd,
there m:
chanze of the reticulum cclis presant, aud poss-
bea gecat deal of cell death, nnd par-
az
ibly also of lysaphocytes thensh+ e3.
Also ay
calculation of Coan NoriLation to t! 2 WARDrion.
chements ct tac lympioid tissue wool TSae] ive
ticuladly with c-errission, withits snore nad well-
oe
defined ranges, the sunnber of a®
“ue sinble i
eels raoy besmall sorapared with thhe numb er at:
Rilled! celis. Flow=
= eer, this ratio w ul deosad on Lvvormatio
ubjects as
: the size and activityof the particles, the extent
resent
RAY
to which they agcregate, and their movearent
culate im
41. Oa the basis of general considerations and
of some experimenveul data and clinical experi-
particles within. the lymph nodes.“Tn addition
there is very little reported work on Uhe distribution of the material withia fie nedes, which
within the tissue, aad the movementof the cells
pest them.
clsRe
u
ence the ‘Disk Gro:op were of the opinion that, could be obtained by autoradiographic study,
the SAMS I“ACiciiva NCrey ab- ; or on the deeres of fibrast
sis and ether lastolozical
sorption nucht welk Deiiess Chective when distri-
bated as 2 series of “hot spots” than whea uai-
oo
for date cfiec ts,
farmly distributed. Fhus, with particulate= racliovc..
a
. Mowevec, @ savers praciical problem
alld hes now
been rccogauized in coanecition with the ishala
ae
tion ofplutconiuim pacticutates, and is now being
coasilered in cciait by a Task Group of Corm-
mittee 1 of ICRP.
42. From dog experiments bein. carried out
in the United States and Som limited sstudies in
made the Task Group coagidered that they
should, for consistency \ithia, the recomunenaations, refer to the whole lymph tissns and not
only to the respiratory lymph nodes. However,
human subjects it hzs become clear that inhalation of plutonium pxrticulates can leadto hin
concentrations of the particulate matecial in the
pulmonary lymph rodes, and thet the mean
radiation dose to ths© pulmontary lymph nodes
until more information becomes available on
some of the subjects mentioned above, litds
and indeed to lympmhonl tissue 2s a whole is
Nkely to be greatly ic excess of that to the lang,
which is at present receded a3 the critical orza
for inhaled particulans matter.
45. The actual dose ratio; are not yet known
with anyprecision bat the Task Group underston] that the mean cose to lymphoid tiiue a3
“R® whole might excee:i that to the hing by a
factor of 10 or marc, and, if the respiratory
lyznph nodes were atanc teken into consideration, the facter cou Be 109 ov perhans much
| Rreater, Lhe problent &s whether lympiroiel tissue
he
as
the
critical
organ, and, if su, achother the dose "sie
(MU,
foe
phvteslaa
ino
putentets
foc
Snow’
be sebstuvieds seduccd Latow the cure
XC
reet valicn
weirht can be put on dose calculations. Data on
tumour productioa from animal experiments ave
of more significance, 7and the results of pyresent
work with dogs, particularly those with lower
amounts ofplut onium, are awaited with interest.
In the meantime, the Task Group 3ve OF
aed
es a whole or respteaeecy lyrapt: rode isaunc ds
particuler showd bs teben
on the residence times of the particulate maaterial
particulate matecial over reauy years. Another
factor to befhen inte cousideration, corna.aa to
all particel ic deposition and espacially to those
involving eoerediters, is that the nurnber of cells
irradiatediis, for the samemeantissns dose, Very
dependent on the purticle size, Minalty, ly:nphocyte migration ts a factor that should be taken
.
into consideration.
can!
ions
calculat
se
45, Inso far a3 meanco
active sources withic a tissue, 2 mean tis: 12 dose
would .probably i: Lat ottce
changes oroduced. Better data ave zlso reauired
ia the Jymph nodes and the solubiliy of the
the
opinion that any Immediate change Jja the dos
lisnit for plutonium ou thes basis of visk to lym
phoid tissue is not warranted.
so meee ome
II.
-13-
a
on
.
ICRP Publication 14
Radiation Sensitivity and
Spatial Distribution of Dose
(Publication 14 app2ars as a
report of two Task Groups,
and not as the official
recormondations of the ICRP.)