Chapter II 



GENERAL NATURE AND PRESENT STATUS 



Recent accomplishments in nuclear physics and engineering have resulted 

 in the production of large quantities of "unnatural" radionuclides and have increased 

 the radioactivity of the biosphere. It is not possible to eliminate all risk, since radio- 

 active contamination is already present. Moreover, it is neither practicable nor 

 sensible to try to eliminate all further sources of risk. Clearly, the hazards should 

 be evaluated in terms of the scientific, social, and economic gains to be achieved. 

 In preparing the 1956 report, we recognized this fact fully and considered the criteria 

 that must be employed in evaluating small but widespread risks, 



A number of other organizations and committees, whose membership represents 

 the most informed judgment available, have also considered the problem. Among these 

 are the National Committee on Radiation Protection and Measurements (NCRP)2,3^ 

 the NAS-NRC Committees on the Biological Effects of Atomic Radiationl.4^ the Medi- 

 cal Research Council^, the United Nations Scientific Committee on Effects of Atomic 

 Radiation^, the International Commission on Radiological Protection (ICRP) "^.S, and 

 the recently formed Federal Radiation Council^. The NCRP, ICRP, and FRC have 

 recommended basic protection standards for radionuclide concentrations in air, water, 

 and the human body for people who work with radioactive materials. All these organiza- 

 tions have given consideration to the exposure of the general population and have agreed 

 that such exposures should be much more restricted than exposures of the smaller oc- 

 cupationally- involved groups. 



With present knowledge, we cannot completely evaluate the risk associated with 

 the continued use of radionuclides that may enter the body. The assumptions on which 

 present radiation protection standards are based must be re-examined repeatedly as 

 more knowledge is accumulated and as production and use of radioactive materials 

 becomes more widespread. Research must continue on uptake, distribution, retention, 

 and biological effects of radionuclides in the biosphere, including man, in order to pro- 

 vide the new information needed as a basis for a progressively informed judgment. 



During 1959, the industrial and medical use of radionuclides increased approxi- 

 mately 20 percent over that of 1958. This increase may be expected to continue. THe 

 use of nuclear energy for the propulsion of submarines and ships and for production 

 pf commercial electrical power is just beginning and may be expected to increase 

 several fold. Although the disposition of the fission products produced in these appli- 

 cations is carefully controlled, the large amounts that will be produced will increase 

 the potential for environmental contamination. We also expect that nuclear energy will 

 be applied increasingly to airborne propulsion and space exploration. Such systems are 

 now under development. A prototype nuclear system for rocket propulsion has been 

 tested, and reactors and isotope units for rocket auxiliary power supplies have been 

 developed. Although such systems produce or contain amounts of radioactivity that 

 are small compared to those produced by nuclear weapons, their use would result in 

 a finite and perhaps significant contribution to the radioactive contamination of man's 

 environment. These applications, and perhaps others not presently foreseen, will 

 introduce new problems, even though there has been considerably less unnatural 

 radioactivity in the atmosphere since the cessation of nuclear tests. 



