Alpha-emitting particles in lungs

"In recognition of the fact that the potential for release of particulate plutonium and transplutonium alpha-emitting elements fromm nuclear power generation facilities poses questions concerning spatial distribution of dose and the resultant biological effects, the NCRP initiated a new NCRP activity concerned with alpha-emitting particles in lungs. It was not intended that a complete review of the subject would be prepared. On the other hand, the study was not to be directed exclusively to recently promulgated controversial proposals relating to standards for alpha-emitting particles in the lung. Rather, the new effort was intended to be a limited-scope study aimed at the development of a statement on the question of whether the current practice of averaging over the lungs the absorbed dose from particulate alpha-emitting radionuclides is a defensible procedure in the practice of radiation protection, and whether exposure limits derived on this basis are more, or less, conservative than those that might result from a precise consideration of the spatial distribution of the dose." --From Preface, page iii.