; 4 The Committee on Pathologic Effects of Atomic Radiation This Committee was composed of scientists well versed in radiation pathology and chaired by Dr. Shields Warren, Direct of the Cancer Research Institute of the New England Deaconess Hospital, Boston, Massachusetts, and was for five years~-1948 1952--Director of the Division of Biology and Medicine of the Atomic Energy Commisston, This group and subcommittees on blood, lung, delayed effects, the and toxicity of ingested radioactive materials review present state of knowledge and found that our knowledge o immediate effects was much greater than for delayed effects, They observed a five year lessened life span for American radiologists, estimated to have received from a few roentgens 1000r of exposure as compared with physicians not using vadiatlon--and agreed that until we had more precise knowledg of the cumulative effects of repeated small exposure of the wh body to radiation the rule of thumb recommended by the Genetic Committee could equally well apply to medical effects, That i no one should receive more than 50r total accumulated dose to reproductive cells by age 30 - and no more than 50r for each decade thereafter, This, they felt, would assure that any lif expectancy curtailment would be exceedingly minor, likelihood of induced leukemia minimal, and the They noted that as fa as effects on the blood-forming organs, the intestinal tract, are concerned, none of these effects have been detected among who have adhered to present permissible dose levels, As for the hazards from ingestion and radioactive materi they confirmed the validity of existing National Committee for Radiation Protection and International Commission for Radiatio Protection recommendations and as for the most important of th ~9- Enclosure II