\SO'T I[AEA-SM-224/607 THYROID HYPOFUNCTION APPEARING ASA DELAYED MANIFESTATION OF ACCIDENTAL EXPOSURE TO RADIOACTIVE FALL-OUT IN A MARSHALLESE POPULATION* P.R. LARSEN Thyroid Unit, Department of Medicine, Peter Bent Brigham Hospital, Boston, Massachusetts R.A, CONARD, K. KNUDSEN Brookhaven National Laboratory, Upton, New York J. ROBBINS, J. WOLFF, J.E. RALL National Institute of Arthritis, Metabolism and Digestive Diseases, Bethesda, Maryland B. DOBYNS Department of Surgery, Case-Western Reserve University, Cleveland, Ohio, United States of America Abstract THYROID HYPOFUNCTION APPEARING AS A DELAYED MANIFESTATION OF ACCIDENTAL EXPOSURE TO RADICACTIVE FALL-OUT IN A MARSHALLESE POPULATION. The increased incidence of thyroid nodularity and carcinoma appearing as a late effect after exposure of the human thyroid to ionizing radiation is well recognized. Despite the high prevalence of thyroid nodularity in Marshallese inadvertently exposed to fall-out in 1954, * This work has been carried out under contract EY-76-C-02-0016 with the United States Department of Energy. 101