212 Health Physics August 2010, Volume 99, Number 2 Table 5. Projected proportion (in %) of total cancerrisk attributable to radioactive fallout, by population, cancersite, and time period. Uncertainty distributions represented by their means and their 5" and 95™ percentiles. Lifetime attributable Attributable risk, risk Population group and cancer type Rongelap Island and Ailinginae exposed community Leukemia Thyroid Stomach Colon Other solid Total Utrik community Leukemia Thyroid Stomach Colon Other solid Total Kwajalein and other mid-latitude atolls Leukemia Thyroid Stomach Colon Other solid Total Majuro and other southern latitude atolls, plus the Rongelap control population Leukemia Thyroid Stomach Colon Other solid Total Entire Marshall Islands population exposed at any time between 1948 and 1970 Leukemia Thyroid Stomach Colon Other solid Total Mean 5% 1948-2008 95% Mean 5% Attributable risk from 2009 95% Mean 5% 95% 78 95 48 64 43 55 39 87 11 36 20 28 91 97 73 78 54 69 83 95 44 60 48 59 43 85 9.2 32 23 30 93 97 71 75 61 73 63 95 52 68 32 47 29 91 13 40 17 26 77 97 77 81 43 62 19 71 4.8 9.4 6.7 10 4.3 32 0.64 3.2 1.5 2.4 45 86 14 19 14 22 26 69 4.5 8.4 6.8 11 5.4 29 0.63 2.8 1.8 2.7 57 86 12 17 15 25 9.0 74 5.0 10 6.5 9.0 2.5 35 0.67 3.1 1.1 1.8 17 87 17 21 14 19 8.4 25 1.9 2.3 1.4 2.2 1.7 6.1 0.26 0.73 0.34 0.50 20 45 3.7 4.8 2.9 4.8 15 28 2.8 3.3 2.3 3.5 2.9 7.0 0.37 1.1 0.60 0.86 36 49 8.5 6.6 4.6 7.9 2.9 21 1.5 1.8 0.96 1.4 0.75 5.1 0.20 0.57 0.20 0.30 3.5 39 4.3 3.8 2.0 3.0 2.2 12 0.47 0.69 0.48 0.76 0.41 2.5 0.069 0.23 0.11 0.16 6.0 27 1.3 1.4 1.0 1.8 4.2 13 0.63 0.90 0.65 1.1 0.67 2.7 0.089 0.31 0.18 0.27 12 29 1.8 2.0 1.4 2.7 0.76 11 0.39 0.59 0.37 0.53 0.22 2.2 0.058 0.20 0.071 0.11 1.4 25 1.2 1.2 0.81 1.2 5.1 21 1.2 1.7 1.0 1.6 0.96 6.0 0.17 0.59 0.27 0.41 12 39 3.4 3.5 2.0 3.4 9.3 24 1.6 2.4 1.6 2.6 1.6 6.5 0.23 0.80 0.46 0.67 23 43 4.7 4.9 3.2 5.6 1.7 17 0.94 1.5 0.66 0.99 0.46 5.0 0.14 0.46 0.16 0.22 3.1 33 2.8 2.9 1.3 1.9 71% (32% to 86%) of those in the Utrik population, 25% (6% to 45%) in the mid-latitude atoll populations, and 12% (2.5% to 27%) of those in the southern atoll populations (Table 5). These numbers reflect the large effect of exposure to radioactive iodine in fallout, primarily due to the active uptake of ingested iodine which is used by the thyroid gland for the production of thyroid hormone. From another perspective, the projected 50 lifetime excess of thyroid cancers in the exposed MI population is 30% of the total projected excess of 170 total lifetime cancers, while the corresponding proportion of projected baseline cancers, 190 thyroid cancers out of 11,000 baseline cancers of all types, is less than 2% of the total (Table 4). Roughly the same percentages (thyroid cancer is ~30% ofthe total cancer excess and ~2% of the total cancer baseline) hold for each of the population subsets represented in Table 4. If not for the large contribution to total cancers due to exposure to radioiodines in fallout, the fraction of leukemia risk (excluding chronic lymphocytic leukemia, or CLL, which is not included in the BEIR VII model) attributable to radiation exposure might be expected to dominate as it does, for example, in the LSS cohort of atomic bomb survivors (Preston et al. 2003) for whom radioactive fallout was at most a very minor contributor to total radiation dose (Young and Kerr 2005). Overall, non-CLL leukemia accounts for about 4% of total projected radiation-related risk with some variation by sub-population, compared to 1.3% of projected baseline risk. Attributable risk for leukemia is high for the