internal doses on Rongerik are assumed to be due entirely to ingestion, ingestion doses on residence islands would not have exceeded a few rem to the thyroid, about 1-2 rem to the large intestine walls, and a fraction of a rem to all other internal organs. Those results should greatly overestimate ingestion doses on residence islands if precautions about eating were taken during known periods of fallout.

V.C.4.3 Summary of Evaluation of Ingestion Doses

The committee acknowledges the concerns of atomic veterans about doses they may have received from ingestion of radionuclides. However, on the basis of an analysis of bounding scenarios for ingestion exposure of participants at the NTS and on residence islands in the Pacific, doses to specific organs and tissues due to ingestion of radionuclides probably were low, especially compared with doses from external exposure, except in rare circumstances. Ingestion doses to most participants probably were around a few mrem or less. Doses of that magnitude are unimportant, so neglect of intakes of radionuclides by ingestion in dose reconstructions for atomic veterans does not appear in most cases to be an important concern with regard to evaluating claims for compensation for radiation-related diseases.

A conclusion that ingestion doses to most atomic veterans were very low may seem unreasonable, especially at the NTS, given the considerable attention that has been paid to ingestion exposures of the US population due to fallout from atmospheric weapons tests at the NTS (NCI, 1997; IOM/NRC, 1999). However, even in the population of the US, doses to most organs and tissues due to ingestion of radionuclides in fallout were substantially less than doses from external exposure (Anspaugh and Church, 1986; Anspaugh et al., 1990; Till et al., 1995; Whicker et al., 1996; UNSCEAR, 2000). The one exception was doses to the thyroid from ingestion of 131I in milk, but even in such cases the principal concern was doses to infants and children who consumed large quantities milk, and doses to adults who drank milk were substantially less. Therefore, ingestion doses normally would have been a concern at the NTS only if participants drank large quantities of milk that had been contaminated by high levels of fallout from recent atmospheric tests. That situation is not known to have occurred at the NTS, and it generally was not a concern in the Pacific, given the absence of sources of milk near the locations of Pacific tests.

V.C.5 Summary of Principal Findings Related to Estimation of Internal Dose

The committee’s evaluation of methods used in the NTPR program to estimate internal doses to atomic veterans focused on methods of estimating inhalation dose. As discussed above, the committee has concluded that internal expo-



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