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* total % % No. Nods. Carcinoma** 58 29 98 86 3.4 6.9 9.2 6.9 1.7 0 1.0 1.1 Combined groups total 4 ts total No. Nods. Carcinoma** 171 50 194 415 2.3 8.0 7.2 5.3 0.6 0 0.5 0.5 & 4 No. Nods. Carcinoma** 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. **kThe carcinomas may be underestimated since all unoperated nodules were considered benign for these calculations. Occult papillary carcinomas not included under carcinoma. Table 3. Group Observed/expected thyroid nodules.* Exposure Age No. Total nodules Carcinoma** Ronge lap <18 42 22/1.6 2/0.4 Utirik <18 85 8/3.3 2/0.8 " " >18 >18 44 79 7/3.5 9/5.7 2/0.3 1/0.6 *Based on unexposed Marshallese prevalence: <18, total nodules 3.94%, carcinoma 1.0%; >18, total nodules 7.9%, carcinoma 0.7%. **Does not include occult papillary carcinomas. - 60 -