EFFECTIVE ARRIVAL TIME (HOURS) O r 6 T 7 T 8 9 TOT 10 Ii 12 13 14 TTT 15 16 1718 1920 TTT GROUND Bikar Pe: ATOLL 00 “370 *OGS0 = FS 70 oS 10412 Ly. 40 60 Nia ifs 220RONGERIK AILINGNAE ATOLL 0 1020 UTIRIK ATOLL 80 100 120 ! 140 160 Lo ATOLL" Ld ; oy 180 200 220 240 260 280 300 320 340 DISTANCE FROM GROUND ZERO (MILES) Figure 1. Approximate gamma dose rates (roentgens per hour) at 3 feet above the ground, one day after the detonation. From Glasstone (40). 2. Residual Radiation To assess potential effects of low-level residual radiation persisting on Rongelap, Utirik, and Bikini, periodic monitoring of the inhabitants of these atolls as well as samples of native flora, fauna, soil, and marine life were performed. These studies are discussed in Section X and Appendix IL. E. Data Evaluation Reevaluations of dose estimates are planned or under way using more sophisticated technology and computer methods currently available, and it is possible dose estimates may be increased. In the meantime the dose calculations previously developed will continue to be used. While quantitative variations in dose estimates have an obvious impact on dose/effect correlations, other considerations are equally important in these studies, especially regarding radiation induction of thyroid neoplasms (caveats regarding thyroid dose estimates are discussed in Section IX and Ap- pendix II). Risk probabilities for development of neoplasms secondary to radiation have classically been derived for malignant tumors of specific organ systems.