EFFECTIVE ARRIVAL TIME (HOURS) 10 9 8 TTT ¢ T 6 0 l2 13 Il TFT 14 15 16 17 18 1920 TT TT TT GROUND ca BIKAR “6! ATOLL a, UTIRIK ATOLL ae Be pro oS(SEB7s 220— RONGERIE Ly 01020 2 jAILINGNAE ATOLL | 40 60 80 100 120 380 os 140 ATOLLW '° a 160 po 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. 2. From Glasstone (40). 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 II. E. Data Evaluation Reevaluations of dose estimates are planned or under way using more so- phisticated 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 Appendix II). Risk probabilities for development of neoplasms secondary to radiation have classically been derived for malignant tumors of specific organ systems.