39 bv Hempeimann. 07.109 Risk for thyroid cancer in the Rongelap people is also similar to that re- 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 levels involved there is a correlation between inci- Utirik group, where none was found. The lower effectiveness per rad in the Utirik children may be Marshallese children appears similar, on a risk per rad basis, to that in the x-raved children studied Ailingnae group, where 2 were noted. and + in the ported for other populations. The dara in Table 25 indicate that at the dose Table 33 Percent Incidence of Thyroid Lesions (20 Years Observation) Age at exposure <10 yr Group Rongelap Ailingnae Rongelap & Ailingnae Utirik X-rayed children (17 yr)107 X-rayed children, low dose (17 yr)!07 Marshallese controls Benign Cancer Benign 84.2 33.3 76.0 0.0 28.0 3.0 3.3 0.0 4.0 0.0 4.3 0.13 iL. 33.3 15.8 3.1 1.8x 10-5 (all ages) 5.4 1.0 Worldwide av. 108 United States197 >10 vr 2.5 X LO-3 (all ages) 0.36-1.7 Cancer 4.4 0.0 3.5 1.0 1.8 10-5 (all ages) 2.9% 1075 (all ages) 0.5-1.6 Table 4 Risk* of Radiation-[nduced Thyroid Lesions (Cases per 10® man-years per rad) Age at exposure < 10 yr Group(years follow-up) Rongelap (20) Ailingnae (20) Rongelap & Ailingnae (20) Utirik (20) Rochester (17)10T Ann Arbor (17)107 Beach & Doiphin (20)123 UNSCEAR(17)!24 ABCC (20)101 ABCC (20)201 Dose range, rads (type) > 10yr Benign Cancer 710-1150 (18,7) 41.9 43.6 42.1 0 2.6 0 2.3 0 335 (av.) (x rays) 20 (av.) (x rays) (x rays) 100- 300 (x rays) 20-1000 (y, 2) <20 (y,") 64.0 24.0 3.5 2.2 17 0.5=15 1.3 (all ages) 0.2 (all ages) 280— 450 (18, y) 280-1150 (TB, y) 60- 9518, y) Dose range, rads 379 135-190 327 31 Benign 10.5 151.1 22.5 89.2 Cancer 7.0 0 6.4 17.8 *Risk is calculated from the equation Risk = No.of cases X L08 dose X years at risk or, alternatively, . Risk = No. of cases x 106 ~ No. of subjects x mean dose < 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). VOB o tao