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 to ts No. Nods. Carcinoma** ts Z No. Nods. Carcinoma** _ total te to No. Nods. Carcinoma** 58 29 98 86 3.4 6.9 9.2 6.9 1.7 0 1.0 1.1 total 17] 50 194 415 2.3 8.0 7.2 5.3 0.6 0 0.5 0.5 total 229 79 292 600 2.6 7.6 7.9 5.8 *Added unexposed people of Rongelap, Utirik, Wotje, and Likiep. 1, Appendix I, for island breakdown. 0.9 0 0.7 0.7 See Table **The carcinomas may be underestimated since all unoperated nodules were considered benign for these calculations. ine luded under carcinoma. Table 3. Group Ronge lap " Utirik " Observed/expected thyroid nodules.* Exposure Age <18 >18 <18 >18 Occult papillary carcinomas not No. Total nodules 42 44 85 79 22/1.6 7/3.5 8/3.3 9/5.7 Carc inoma** 2/0.4 2/0.3 2/0.8 1/0.6 *Based on unexposed Marshallese prevalence: <18, total nodules 3.9%, noma 1.0%; >18, total nodules 7.9%, carcinoma 0.7%. **Does not include occult papillary carcinomas. ~ 60 - carci-