DRAFT ~13- Previous studies (1, 22) in the Marshall Islands and the analytical data reported here indicate that only ©°Co, 39%Sr, !37Cs and Plutonium isotopes contribute to the internal dose. The dose calculations resulting from the inhalation and ingestion of these nuclides have been made using the most recent models, transfer coefficients and turnover times available. The dose from ®°Co was based upon a single exponential model with a biological half time of 10 days (17). whole body was taken as 0.3. was used. The transfer across the gut to For !37Cs a two component exponential function 100% of the 137Cs ingested is assumed to reach the whole body. Of the total !3’Cs reaching the body, 15% has a biological half time of 1 day and 85% has a biological half time of 115 days (8). The critical organ for 99Sr dose calculations is bone marrow. The doses from 2°Sr presented in this report are for bone marrow and are calculated using the method developed by Spiers (9, 10, 11) and used in the UNSCEAR reports (12). This model calculates the dose using a quality factor (QF) of 1 without the use of an "n" factor for non-uniform distribution in the bone (13). Under these conditions the bone marrow doses should be compared to the 0.5 rem per year guide for members of the public rather than the 3 rem ‘per year criteria (14, 15, 16) used if mineral bone doses are calculated using an "n" factor of 5 (13, 17). The bone and liver doses resulting from 239,24°Py were calculated using the ICRP lung model (18, 18A) and the most recent paramters for transfer from the lung, across the gut wall and for retention time in the critical organs (18, 19). A summary description of this model and associated transfer and retention coefficients is given in a recent paper by Martin and Bloom (20). — OR sci