29
Marshallese children appears similar, on a risk per
rad basis, to that in the x-rayed children studied
by Hempelmann.!07.109 Risk for thyroid cancer in
the Rongelap people is also similar to that reported for other populations.
The data in Table25 indicate that at the dose
levels involved there is a correlation between inci-
dence of thyroid lesions and the estimated dose to
the gland. On the 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 2 were noted, and4 in the
Uuritk group, where none was found. The lower
effectiveness per rad in the Utirik children may be
Table 33
Percent Incidence of Thyroid Lesions (20 Years Observation)
Age at exposure
<10 yr
Group
> 10 yr
Benign
Cancer
Benign
Rongelap
Ailingnae
Rongelap & Ailingnae
84.2
33.3
76.0
3.3
0.0
4.0
11.1!
33.3
15.8
X-rayed children (17 yr)19
X-rayed children, low dose (17 yr)!07
28.0
3.0
Utirik
Marshallese controls
Worldwideav. 108
United States!9?
0.0
0.0
1.0
1.8 10-5 (all ages)
2.5 & 10-5 (all ages)
4.4
0.0
3.3
3.1
4.3
0.13
0.36-1.7
Cancer
1.0
5.4
1.8 x 10-5 (al! ages)
2.5 K 10-5 (all ages)
0.5-1.6
Table 34
Risk* of Radiation-Induced Thyroid Lesions (Cases per 106 man-years per rad)
Age at exposure
< 10 yr
Group (years follow-up)
Dose range, rads {type)
> 10 yr
Benign
Cancer
710-1150 (18,7)
41.9
2.6
Rongelap & Ailingnae (20)
280-1150 (If, y)
42.1
Rochester (17)!97
335 (av.) (x rays)
Rongelap(20)
Ailingnae (20)
280- 450 (18, y)
Utirik (20)
43.6
60- 95 (1B, y)
Ann Arbor (17)107
0
64.0
20 (av.} (x rays)
Beach & Dolphin (20)123
24.0
(x rays)
UNSCEAR(17)224
100- 300 (x rays)
ABCC(20)101
<20
379
Benign
10.5
Cancer
7.0
0
135-190
151.1
0
0
31
892
178
2.3
327
22.5
6.4
5.5
2.2
1.7
0.5-15
20-1000 (y, 2)
ABCC (20)!01
Dose range,rads
1.3 (all ages)
(y,n)
0.2 (all ages)
*Risk is calculated from the equation
.
No. of cases & 108
Risk = ~———_—___—"__ ,
dose x years at risk
or, alternatively,
Risk =
No. of cases « 106
No. of subjects x mean dose x mean No.of years at risk"
Both equations give almost identical results for the Marshallese because of the uniformity of the data, No correction
has been made for expected numberof cases because the expectation among unexposed subjects is too low to affect the
results (see Table 33}.