39
Marshallese children appears similar, on a risk per
rad basis. to that in the x-raved children studied
by Hempelmann. 107-109 Risk for thyroid cancerin
the Rongelap people is also similar to that reported for other populations.
The data in Table 25 indicate that at the dose
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 2 were noted. and 4 in the
Utirik group, where none was found. The lower
effectiveness per rad in the Utirik children may be
levels involved there is a correlation between inci-
Table 33
Percent Incidence of Thyroid Lesions (20 Years Observation)
Age at exposure
<10 yr
Group
Benign
Rongelap
> 10 yr
Cancer
84.2
Ailingnae
Rongelap & Ailingnae
Utirik
3.3
33.3
76.0
0.0
X-rayed children (17 yr)!0?
X-rayed children, low dose (17 yr)'07
33.3
15.8
3.1
1.8x 10-5 (all ages)
2.5 « 10-5 (all ages)
5.4
4.3
0.13
1.0
0.36-1.7
Cancer
11.1
0.0
4.0
0.0
28.0
3.0
Marshallese controls
Worldwide av. 108
United States?
Benign
4.4
0.0
3.5
1.0
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 10® man-vears 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
151.1
22.5
89.2
7.0
0
6.4
17.8
Rongelap (20)
Ailingnae (20)
Rongelap & Ailingnae (20)
Ctirik (20)
710-1150 (IB,y)
280- 450 (I8,y)
280-1150 (IB, y)
60- 95 (18, y)
41.9
43.6
42.1
0
2.6
0
2.3
0
Rochester (17)!07
Ann Arbor (17)!97
Beach & Dolphin (20)!23
UNSCEAR (17)124
335 (av.) (x rays)
20 (av.) (x rays)
(x rays)
100— 300 (x rays)
64.0
24.0
55
2.2
1.7
0.5-15
ABCC(20)19!
ABCC (20)191
~
20-1000 (y, 7)
<20
1.3 (all ages)
(y, 1)
0.2 (ali ages)
“Risk is calculated from the equation
.
No. of cases x 108
Risk = ~————___—___- ,
or, alternatively,
dose X years at risk
No. of cases x 108
Risk = No. of subjects X mean dose x mean No. ofyears atrisk’
Both equations give almost identical results for the Marshallese because of the uniformity of the data. No correction
has been madefor expected number ofcases because the expectation among unexposed subjects is too low to affect the
results (see Table 33).