i
i
|
Marshallese children appears similar, on a risk per
rad basis, to that in the x-raved children studied
by Hempelmann. !97.109 Risk for thyroid cancer in
the Rongelap people is also similar to that reported for other populations.
The data in Table 25 indicate that at the dose
levels involved there ts a correlation between inci-
dence of thyroid lesions and the estimated dose to
the gland. Onthe basis of the incidence per rad in
the high exposure Rongelap children, about 2
children with adenomas would be expected in the
Ailingnae group, where ? were noted, and 4 in the
Uuirik group, where none was found. The lower
effectiveness per rad in the Utirik children maybe
Table 33
:
rw ee ne ee
‘
‘
29
Percent [Incidence of Thyroid Lesions (20 Years Observation)
Age at exposure
<€10 yr
Group
Benign
Rongelap
> 10 yr
Cancer
84.2
Ailingnae
33.3
X-raved children (17 yr)197
28.0
Rongelap & Ailingnae
Utirik
X-rayed children, low dose (17 yr)10?
Marshallese controls
3.3
0.0
United States}?
4.0
0.0
3.0
0.13
4.3
1.8 x 10-5 (all ages)
Ii
4.4
15.8
5.1
3.5
1.0
0.0
5.4
2.5 X 10-5 (all ages)
0.36-1.7
Cancer
33.3
76.0
0.0
1.0
Worldwide av.108
Benign
1.8 x 10-5 (all ages)
2.5 * 10-5 (all ages)
0.5-1.6
Table 34
Risk* of Radiation-Induced Thyroid Lesions (Cases per 108 man-years per rad)
Age at exposure
< 10 yr
Group(years follow-up)
Dose range, rads (type)
> 10 yr
Benign
Cancer
Dose range, rads
Benign
Cancer
379
135-190
327
31
10.5
16.1
‘225
89.2
7.0
0
6.4
17.8
Rongelap (20)
Ailingnae (20)
Rongelap & Ailingnae (20)
Uuirik (20)
710-1150 (18,7)
280— 450 (I, y)
280-1150 (18,y)
60- 95 (IB, y)
41.9
43.6
42.1
2.6
0
2.3
0
Rochester (17)197
335 (av.) (x rays)
64.0
3.5
Ann Arbor (17)!97
20 (av.) (x rays)
Beach & Dolphin (20)!3
(x rays)
UNSCEAR(17)!4
100- 300 (x rays)
ABCC (20)!91
20-1000 (y, 7)
ABCC (20)102
<20
(y,7)
24.0
2.2
1.7
0.5-15
1.3 (all ages)
0.2 (all ages)
*Risk is calculated from the equation
Risk = No.of cases x 106
~ dose x years at risk ’
or, alternatively,
.
No.of cases x 10
Risk =
‘
=
=“
oa
oo
.
°
a
28.
caetl
No. of subjects X mean dose x mean No.of years atrisk ™=.
Both equations give almost identical results for the Marshallese because of the uniformity of the data. No correction
has been madefor expected numberofcases because the expectation among unexposed subjects is too lowto affect the
results (see Table 33).