APPENDIX IV INHALATION OF STRONTIUM 90 Aluminum oxide has been suggested as a possible trap for Sr°° during formation of particles in an atomic explosion. Consideration is therefore being given to the effect of this type of conglomerate material upon inhalation into the lung. Aluminum oxide has been implicated as the causative agent of a pneumoconiotic disease (Shaver's Disease ) among workers inhaling f'mes of calcined bauxite, The microscopic pathological picture has been described as a diffuse fibrotic process. The alveolar walls were thickened and in places the alveoli were replaced by fibrous tissue. Hyalinization was considerable. The fibrosis was not nodular in type. This mechanism may result in somewhat greater trapping than the conventi onal rule of thumb regarding the retention of particulate n-atter in the lungs.* However, for SUNSHINE we shall use the standard MPC of 2 x 10-1° pc/mlof air. It may be of some interest to calculate the inhalation-limiting world dose of Sr°9. This calculation is even more idealized than those given in Appendix I, especially since it assumes that all the Sr°° created is available in aerosol form uniformly distributed throughoutthe earth’s atmosphere. We take as the volume of the earth's atmosphere, 5 & 10% cc, The required amount of Sr®° aerosol to bring the atmosphere up to tolerance is then (2 X 10-19) (5 X 107*) = 105 uc = 10° curies, This activity of Sris created by a fission energy equivalent to 5000 MT, Pending better evaluation of the inhalation hazard, this figure is to be taken cum granosalis. *International Commission on Radiological Protection; NBS Handbook 47. 89