exposed on Rongerik. It was reported that the gross beta activity in urine obtained from the Ailingnae group was about 50% of that of the Rongelap group. Thus, it can be surmised that a rough estimate of thyroid dose to the Ailingnae people was about 0.75 Gy (75 rad). The radiation dose received from external exposures must be added to these numbers to estimate the total thyroid dose. However, when observations of thyroid abnormalities began, a more careful evaluation of the dosimetry was made, including the contributions from iodine-131, 132, and 135. Revised estimates of the thyroid doses in the Marshallese by James (36) and Lessard et al. (37) are shown on Table 4. The dose reassessment by Lessard et al. suggested higher absorbed doses than those estimated by James because of differences in assumed isotopic ratios. TABLE 4, Estimeies ofThyroid Dose [Gy,(rad)} in tbe Exposed Populations By Age (Years) at Exposure Abell Rongelep Gy Karty Eothnetes* <lé yr 50 (rad) Ailingnae Gy 16-18 yr 81-18 (810-1800) 7S (rad) Rongerik » Vari Gy _ (tad) L450 (1964) >18 yr 3.48.1 (334-810) 335 (335) al. 10-18 yr >13 yr 18-50 12-17 ) (190) (135) 135 7.40-13.0 NID _ _ _ _ — 060-095 3.040 27-67 15-25 27-47 (30-40) (270-670) 1611 (1800-$000) (1200-1700) (1000-1100 f (275-450) (95) L¢ <10 yw (740-1300) (150-250) (7-46) | -23 (280-290) ~ LS-Lé (150-160) * Original dose estimate (rad), adult population only. N/D = No Data The doses to skeleton and marrow initially were assumed to be small compared to the external doses received. Actually, before the thyroid abnormalities became apparent, it was assumed that "the internal hazard to the contaminated inhabitants of the Marshall Islands is minimal both from the acute and the long range point of view" (5). However, the long-term doses to the skeleton and marrow might be importantin assessing of stochastic effects (see 4.4.4). Also, doses to the gastrointestinal tract may have been significant if these nuclides were inhaled in an insoluble form. (Approximately 61% of inhaled insoluble aerosols >1 micron in diameter will be returned into the pharynx and swallowed). Indeed, high amounts ofactivity were detected in the gastrointestinal tracts of 23