............ ...... ....::..) ..... 2. Actions taken to reduce exposures should be those which show promise of significant exposure reduction when weighed against total expected exposures and the “costs” “ in this context, are measured “costs, of the actions. primarily in terms of costs to the Enewetak people as constraints on their activities or as dollar costs for cleanup or remedial action. In these evaluations, it should be emphasized that dosages through various pathways are estimated on the basis of environmental data and considerations of expected liting ~,~>ile l’radiation standards” patterns and dietary habits. do not exist for environmental contamination levels in substances such as soil and foodstuffs, there is general agreement in terms of conservative models of these pathways and the relationships between a certain level in the en~tironment and the likely dose to result from- the pathway exposure. ........... ......... .. ...4 — The area of plutonium in soils, however, is one for which there is no general agreement as to the quantitative relationship between levels in soils and dosages to be expected through the the primary one through which man can inhalation pathway, The ICRP recommends receive a significant dose from plutonium. a ma.stimum permissible average concentration (.MPC) of 1 picocurie per cubic meter (pCi/m3) of air for “insoluble” plutonium and O. 06 pCi/m3 for “soluble” plutonium for unWhile the plutonium in the soil at Enewetak restricted areas. is thought to be typical of world-wide fallout, and therefore insoluble, O. 06 pCi/m3 vdl be used for the sake of conservatism. Append~ix -% of Enewetak Radiological Survey, N-VO-140, presents hvo possible methods for deri~ing the exposures that may occur through the inhalation pathway for plutonium in soil. (This is the pathway of interest for the present although it is recognized ingestion may become more that for the very distant future, Table 250 of A pendix E shows that important by comparison. liver, and lung from 23 $ Pu is expected to exposure to bone, be a few hundredths of a rem in 30 years for pathways other than inhalation. ) This material is produced as .4ttachment I of this section. The two methods presented are the “resuspension-factor” Soil concentrations approach and the ‘mass-loading” approach. of 239Pu that would be associated with the standard for 239Pu in air (O. 06 pCi/m3) by the h-o methods are: ... .... ........... .... .. .. .... ... .... ... . . ......... ................ ... .. ...... ......... 111–7 t