“Acknowledgment. Tne authors gratefully acknowledge support by the Fallout Studies Branch, Division of Biology and Medicine, U. 5. Atomic Energy Commission. The assistance of the Office of Criteria end Standards, Division of Environmental Radiation, and the Southwestern Radiological Health Laboratory of the Bureau of Radiological Health, ‘ . for his invaluable aid in preparing this paper. rh Finally, we should like to thenk our colleague, Robert List, ae ee Re ee ee one wen ‘ appreciated. we srteee weenie eee Public Health Service, Department of Health, Education and Welfare is