being placed on investigations of the fundamental mechanisms involved in the induction 

 of osteosarcomas by internal emitters. 



The ICRP and NCRP have made available an invaluable collection of information 

 and methodology and have chosen wisely on the basis of present knowledge. Yet there 

 are areas where much work still needs to be done. We feel that part of our function 

 is to highlight such areas and to help stimulate scientific efforts directed toward sup- 

 plying the needed information to those charged with the responsibility of setting the 

 maximum permissible dose standards. 



A perusal of this report will indicate that, while progress is being made and 

 advantage is being taken of new approaches, there are many areas in which further 

 information is essential. We recommend that special attention be given to the fol- 

 lowing areas: 



1. Studies in a variety of animals of long-term physiological and pathological 

 changes resulting from chronic irradiation by deposited radionuclides should be con- 

 tinued, with increased reference to variables such as age and nutritional status of 

 the animal, chemical and physical form of the nuclide, route of administration, and 

 duration of exposure. 



2. Studies of the effects of such variables on uptake, retention, and anatomical 

 distribution of radionuclides should be continued, and, where possible, such data 

 should include man himself. 



3. Further studies of the relationship between excretion levels and body content 

 of radionuclides should be carried out, with particular reference to those not readily 

 measurable by external counting techniques. Studies aimed at finding methods for 

 promoting the excretion of deposited radionuclides are also of prime practical im- 

 portance. 



4. Study on a global scale of the accumulation and retention of fallout radio- 

 nuclides in man should be pursued on a continuing basis as fully as is necessary to 

 obtain representative information, since this may be an irreplaceable opportunity 

 to secure this type of human data. For similar reasons, full emphasis should be 

 given to continued study of groups of persons who have been exposed to radioactive 

 materials and of populations that have lived in areas having greater than average 

 levels of radioactivity. 



5. Concepts that are used in the assessment of relative degrees and hazards of 

 exposure to radionuclides, such as RBE and critical organ, should be kept under con- 

 tinued scrutiny with the accumulation of new basic knowledge. 



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