Table 2. Percent of unexposed Marshallese (born before 1954) with thyroid nodules. Established (1958) group (Rongelap) Age group (1954) <10 10-18 >18 All Added groups* Combined groups ts te No. Nods. Carcinoma** hs to No. Nods. Carcinoma** total te % No. Nods. Carcinoma** 58 29 98 86 3.4 6.9 9.2 6.9 1.7 0 1.0 1.1 total 171 50 194 415 2.3 8.0 7.2 5.3 total 0.6 0 0.5 0.5 229 79 292 600 2.6 7.6 7.9 5.8 0.9 0 0.7 0.7 *Added unexposed people of Rongelap, Utirik, Wotje, and Likiep. See Table 1, Appendix I, for island breakdown. **The carcinomas may be underestimated since all unoperated nodules were considered benign for these calculations. Occult papillary carcinomas not included under carcinoma. Table 3. Group Ronge lap Exposure Age <18 " >18 " >18 Utirik Observed/expected thyroid nodules.* <18 No. Total nodules Carcinoma** 42 22/1.6 2/0.4 B85 8/3.3 2/0.8 44 7/3.5 79 *Based on unexposed Marshallese prevalence: 9/5.7 <18, 1/0.6 total nodules 3.9%, noma 1.0%; >18, total nodules 7.9%, carcinoma 0.7%. **Does not include occult papillary carcinomas. ~ 60 - 2/0.3 carci-