V in the environs, considering all possible sources, are within limits. The AEC's Health and Safety Laboratory (HASL) conducts a radlological monitoring and surveillance program on a wide geographical scale and for a variety of components of the bioenvironment. Among the surveillance activities are: (1) worldwide deposition of strontium 9° (Precipitation) Program; (2) the radionuclides in surface air promo, and high altitude balloon air sampling prouran; (3) the radiostrontium in milk and tapwater “program; (4) the HASL diet studies; and (5) the program on concentrations of strontium-90 in human vertebra. The U. S. Public Health Service (USPHS) operates (1) a Pasteurized Milk Network consisting of 63 sampling stations, 61 of which are located in the U. S., one in Puerto Rico and one in the | Canal Zone;'and (2) the Radiation Alert Network (RAN) for routinely sampling air at ground level on filters, consisting of 73 stations throughout the U. S.. In addition to these routine network programs, the USPHS conducts periodic surveys for radioactivity in food and diet, and semiannual analysis of water for tritium at 10 surface water sampling stations in the U.S. Various other national and international health agencies also operate extensive programs to evaluate exposures to the public from the environment vie air, water and diet sampling programs. The USPHS has also, as a matter of perspective, developed data on the very much larger exposures to the public from diagnostic and therapeutic medical exposures. Such exposures ere largely from X-ray equipment not under AEC regulation. There is no single inventory of the total number of curies that have been created from all sources for all purposes. While this could be collected, continuous surveillance of important areas of the bioenvironment