mmm mt cn te ae One ae te ener nee ee me eT a eRe Ame areas. eee a 7 RC? a if UA Lk + This work also includes determining the levels below which radio- activity is harnless to man or his environment, and measuring radioectivity in and around working areas to make certain that these permissible levels arc not exceeded. The amount of radioactivity in discharged wastes that can be conSicered allowable from the biological and human standpoint must be determined. New data aro needed to give added assurance that present disposal techniques are acccptable or to indicate changes advisable from the sinndpoint of public health or economy of Comaission operations. Commission studies in this field now include: 1. Research on utilization of radioactive isotoves by plants and animals. Low levels of radioactivity in water or soils become a hazard to humans and higher animals to the extent that this activity is taken up and concentrated by plants and lower animal forms which, in turn, serve as food for higher animals or man. 2. Research on monitoring mothods. Work is still necessary to develop routine methods of radioactivity detection suitable for measurements of low intensity radiation in water, air, and food. 3. Research on normal radioactivity in man and nature. _ Data on the radioactivity normally present in rocks, soils, natural waters, plants, animal life, and the human body are needed as a basis for considering disposal techniques. Research proposals approved by the ADC during the quarter in these and other related fields are listed in Appendix D. Permissible Levels of Exnosure The operation of production plants in the atomic energy progran of necessity discharges some radioactive waste products into the environment. The complete elimination of radioactivity from the environnent is not necessary. Throughout its existence the human race has been subjected to radiation by cosmic rays and natural radioactivity in soil, rocks, and water. Living organisms have some resistance to damage by radiation, and the problem is to determine the level of this resistance. Exposure to certain amounts of radiation is kmorm to harm man. However, the imposition of unjustifiably risorous standards for permissible ex- posure would result in excessive onerating costs and lowered operating efficiency. Research is therefore under way to determine as accurately as possible the optimum lcvel of protection which must be given to populations located in the vicinity of atomic energy plants. External radiation. Living organisms can repair a small amount of radiation damage as fast as it occurs. Determining the level of this “tolerance dose" for man and animals is under study. - 53 “ff -li-