(Nucl Safety; Abb: MPC) The quantity of radioactive material in air, water, or food which might be expected to result in a maximum permissible dose to persons inhaling or ingesting them at a standard rate of intake. See: Radiation Protraction Guide; Radioactivity Concentration Guide. Note: Maximum average concentrations of radionuclides to which a worker may be exposed 8 hours a day, 5 days a week, and 50 weeks a year have been recommended by the National Committee on Radiation Protection