- 51 VIII . , Summary of Recommendations he following recommendations apply to alpha-emitting hot particles where a hot particle is defined as a particle _that contains sufficient activity to deliver at least 1000 rem/yr to the surrounding lung tissue. For isotopes having half-lives greater than one year, this would correspond to particles containing at least 0.07 pCi of alpha activity. °? It is recommended that: l. “Ff For occupational exposure MPLPB = 2 hot particles pos C fou MPC, for Pu-239 = 3.5x10716 uci/m1®® 2. For non-occupational exposure MPLPB = 0.2 hot particles MPCa for Pu-239 = 9x10718 uci/mi®? .87/ These particulates would consist of compounds of Pu and the other actnides which fall into Class Y material in tne ICRP Task Group Lung Moecel. These materials vrould be retained for years in the lung. See for example, ICRP Publication 19, Oc. cit. ‘p. 6. Since only particles in the size range of 5 u and below & = = _ 88/ “4 jae fue it This MPCg applies for particles contai: ng 0.07 pCi of Pu-239. For particles containing more than 0.07 pCi the MPCa could be inercased proportionateiy. For particles containing less thar 0.07 pCi the existing MPCa=4él07++ cci/m would apply. The MPCa fer hot particles of other isoctovcis and mixtures of isotores sheuld be established on a similis basis with consideration given to the half-life of the isctse:. e9/ Ibid. ee uo ct qv here. If the half-life is less than or close to 1 year the Of 0.07 pCi can be adjusted upward through appropriate caicu t-: BH dnt (0 mM cr ' qt diameter would be Cevosited in the deep respiratory tissue, ¢! in effect sets an upver limit for the particle size of inter Je + a — *