3. Island interior—0.059 mSvy-! (5.9 mrem y-}). 4. Beaches and lagoon—0.50 pSv y~! (0.050 mrem y~'). The average external effective dose rate attributable to such a living pattern in 1995 on Rongelap Island is about 0.11 mSv y~! (11 mrem y~!). The natural external background effective dose rate is about 0.22 mSv y—! (22 mrem y-!). Beta Radiation It is impossible to predict precisely what the beta dose to the skin will be, but it is clear that the “shallow dose” due to both beta particles and external gamma exposure will be only slightly greater than the dose estimated for external gamma whole-body exposure. This higher “shallow dose” will occur primarily to the most exposed parts of the body, usually the arms, lower legs, and feet. The skin is a much less sensitive organ to radiation than other parts of the body; for example, the weighting factor for stochastic risk recommended by the ICRP for skin is 0.01, compared with 0.20 for gonads, 0.12 for red bone marrow, colon, stomach, and lungs, and 0.05 for breast, bladder, dose for adults due to ingestion of P7Cs and Sr can be used as a conservative |e intake beginning in infancy. In calculate only the doses to adults. Strontium-90 Several models have been defeloped over the years to estimate the cycling gnd retention of 99Sr in the body as a functiqn of age to calculate age-dependent dose] conversion factors. We have previously uged both the model developed at Environmental MeasurementLaboratory (EML) (Rivera, 1967; Bennett, 1973, 1977, 1978; Kluse&, 1979) and that of Papworth and Vennart $1973, 1984). The two models give very similarfresults, with the biggest difference in results dccurring for persons between the ages of 5 and 15 y. Both models are empirical modelg based on measurements of 99Sr in the diet and corresponding measurements of “Br in autopsy bone samples. The retentions and turnover rates, and discrimination factors if the models are determined by regression fanalysis or equation solution fitting of the olfse No particular correlation is made liver, and thyroid (ICRP, 1990). Consequently, the beta contribution to the total effective dose is extremely small. Internal Exposure function of bone compartments fs generally outlined in the ICRP model (ICRH, 1972, 1979, Cesium-137 The conversion from the intake of137Cs to the effective dose for the adult is based upon the ICRP methods described in ICRP Publications 30, 56, 61 (ICRP, 1979, 1990, 1991b), which are based on Leggett's model (Leggett, 1986). We have combined the ICRP model for charged-particle emissions for the betaparticle emissions (E = 0.51 meV) from 137Cs and the methods of Leggett et al. (1984), and Cristy and Ekerman (1987a and 1987b) for the photon emission (E = 0.66 meV), associated with 137Cs decay (137mBa) to generate the final dose conversion factors. The biological half-life of 137Cs is determined as a function of mass (i.e., age) by the methods described in the Leggett model. In a separate report, we estimated the comparative doses between adults and children (Robison and Phillips, 1989). The results indicate that the estimated integral effective 1990). The bone is assumed to be cbmposed of a structural component associateq with bone volume, which includes the compact cortical bone, a large portion of tha@ (trabecular) bone, and a metabolif associated with bone surfaces. compartments are then identifiedi cancellous component effect, three two within mechanical structure and integrity of the bone, the bone volume and one within the bone surface. The bone volume is asspciated with and the bone surface is involved with the metabolic regulation of extracell@lar calcium. Much use is made of general dat about age- dependent bone formation within these compartments and, consequently, fhis modelis not as dependent on radionuclidejspecific data as the other models. Wewill not discuss further ddtails of these models, but refer the reader tojthe onginal articles and their associated references for