report; the maximum permissible lung burden (MFLB) and the maximum permissible concentration in air ({MPC,). The MPLB is the total amount of a given radionuclide in the lung of an average size man that will result in the lung being irradiated at the maximuin permissible lung dose (MPLD). py The MPC, is the concentration in air that will result in an average adult male obtaining a MPLB and hence a MPLD by breathing the air. . : 7 It is important to recognize that the MPLD is the °F primary stan@ard; it applies to all radionuclides and radiation sources. The MPLB and the MPCa are derived standards and are specific for a radionuclide. These derived standards are related to the biological properties of a radionuclide and to the form of radiation it emits. | Table I lists the existing exposure standards for em~ —_ . ployees of the nuclear industry that apply to Pu-239 in insoluble form. The MPLD of 15 rem/yr is included in the recommendations of the Intcrnational Commission on Radiological Protection -(icrp) 2 the National Council on Radiation Protection and Measurements 8/ (NCRP)?, and the Federal Radiation Council ICRP Publication 9, Recommendations of the International Commission on Radioloaical Protection Pergamon Press, o/ New York, 1966, p. (Accented Seoterber 17, 14. NCRP R epert No. 39, Basic Radiation Prot NCRP PuLli cations, Washington, 9. ¢., Jan. 15, i 1s 19%.