2
genie effect in rats anddogs is equal on a rad basis
dibabe
thyroid dose from abserprion af radioiodines in
tiHout, considers the shorter-lved isotopes to be 4
times as energetic as 88) The more cnergene bets
radiation with a higher dose rate and longer range
gives anoruniter tissue distribution of radiae
tien than is produced by EL Phas aiglit explain
whythe ticidence of thyroid lesions in the children
fae
receiving 1000 rads falls an a line comresponding to
babe
1000 rads of x-radiation (Figure 44). ar i aight
indicate that the radiotodiae exposure was about
TO ines as ctfecrive as /Y PE alone would have been
ieee Chale Thus the twe boys with ateaply of
the thyraid: may have bad doses te the wland com,
parable with 40000 te GU00 rads ar morc of siracliations,.
teal
were
.
’
hee
bade
.
sant
woos anal
u
‘»
fe
1
Petal age, an weeks
. [ .
Abogado ‘
u.
Hi
Ia
da ededn enna
lo that of x rays. Walinder et al. have reported
similar findings. °4-6Dunning. ©jn estimating
ee Gaal *
Ma lars
Nahaala
Figure 18. ‘Vivnsdal uptake of MU per granny
versus age. (From Fans et ale)
3. The Development of Thyroid Abnormalities
From In Utero Exposure
The development of thyroid adenomas in one
of the Marshallese bows exposed in utere as of ine
terest. Four children were exposed urate uy the
higher radiation group, one at the end of unesec.
ond trimester ad (woot dhe end of the first uri
mmesters in the lower dose Ronygelap group, ane at
(he cod of the second trimester, Ouly the boy
in the higher dese group and cx posca in the second
trimester has developed thyraid lesions. Several
cases have been reported af children who had
myxedema following a ates exposure during
lreatsnent of the mother with barge doses of cadioiodine. PT LLowever,. this Marshallese buy ap.
pears tobe the first reported case af thyroid adenos developing presumably drome waders expo
sure to tacdiomdines.
fates Uavroid dase calcuLidans are pot possible. since insufficient data are available on fetal
thyroid uptake of racboiedines front the nother at
Various stages of gestation! Figure 48 shows thy.
roid function of the human fetus, The gland is not
thought to begin to function and to accumulate
iodine wndl about the Teh week of vestauon Phe
At the tine of exposure ofthe Marshallese boy
(about 22 to 24 weekso the Uhvroid should have
been actively functioning. He received $73 rads of
ganna radiation but the dase fron radioiadines is
uncertain, In view of the high uptake of radicjodines per gram by the fetal thyroid at 22 weeks,
the tivreid douse might be expected to be high.
However, since i appeats from: our data that
longer latent: periods are associated with lower
doses of radiation tothe Ghyroid, His dikely drat
the Uhivroid in this baw ex posed: audereeen cd a
lower dose than thatia Marshallese children exposed ata voung aie. “Miso, this bay and the others
exposed acatee have shown no dnpaurinens ta
growth and development. Iois of uiterest (hac the
mother of this bow has ed developed any thyreicd
aboormalities and appears ta be curharoid. The
two children exposed at the end al the first teamester probably had nonfincudoning primordial tiv.
roid whines at dat Gane so that the wlhands gecewed
only the gaia exposure and were therefore less
lkeby tadeveiop thyroid abnornialities. None of
the four childecn exposed acatero has show a tier.
cephaly or mental retardation, which have been
noted in some of the Children exposed gr ctere it
Japan.
V, Neoplasia
Among the late cffeets af radiation, (he eabancement of the develapmeat of neoplasia his been
well documented, Ea irradiated aninvals, malig.
Hancies pot anky say be induced at an carer awe
but appear in increased numbers, fa the Japanese
atom booth sucvivers, loukeawa and thyroid neo:
plasia have shawn the mast clear-cut asseciation
with radiaven exposure, though more recently