function blood tests and thyroid examinations by a specialist in endocrinology or thyroid surgery. Othertests are performed on a regular basis in an attempt at early detection of malignant nonthyroidallesions. Thereis also ongoing monitoring for clinical evidence of immune competence, for exposed persons may be at increased risk for unusual manifestations of infectious diseases. Medical examinationsand services performed during this three-year reporting period were conducted primarily aboard the Liktanur I] and the Liktanur III, vessels chartered from US. Oceanography. Exceptions, as in the past, included the use of Brookhaven National Laboratory facilities on Ebeye and, when necessary, Marshallese medical dispensaries on Rongelap, Utirik, and Mejato. Laboratory support during the medical missions is provided by several technicians. Routine blood countsare performed ona J.T. Baker 5000 electronic particle counter and sizer. Leukocyte differentials and phase contrast platelet counts are part of each hemogram. A variety of nonhematologicaltesting services is provided, including bacteriology, stool examination, and urine testing. In the past a battery of manual clinical chemistry tests was carried out using commercial spectrophotometric kits. Recently, however, Eastman-Kodak’s DT-60 and DTSC analyzers were added to increase the variety of chemistry tests available in the field and to improve the turn-around time for results; this has significantly improved laboratory operation. Fortunately, there have been few problems associated with transport, operation, and handling of the new equipment on board ship, even during bad weather. A BeckmanElectrolyte 2 analyzer is used to measure sodium and potassium in serum and urine. Roentgenographic services are performed with a Bennett standard x-ray unit and mammography unit, both of which are contained in a separate module on the deck of the ship. Serum is usually collected from most examinees and frozen for subsequent testing. Referral laboratories have included Bio-Science Laboratories and Accupath in Honolulu for special chemistries and serologies; Pathologists’ Laboratories, Inc., Honolulu, for Papanicolaou smears and other cytology; Brookhaven National Laboratory's clinical laboratory for general chemistry and alpha fetoprotein analysis; Hazelton Biotech- nologies Co., Vienna, VA, for hormone assays; Michael Reese Hospital and Medical Center(Dr: A. B. Schneider, Department of Endocrinology and Metabolism), Chicago, for thyroglobulin analysis; Medical Microbiology Division, University of California, Irvine, for chlamydia culture and serology; and the Eugene L. Saenger Radioisotope Laboratory, University of Cincinnati, for antimicrosomal and antithyroglobulin antibody testing (Dr. Harry Maxon). The Marshall Islands Medical Program is deeply indebted to the many outstanding physicians who, despite the inevitable personal inconvenience, participated in the medical team visits of 1985-1987. It is fair to say that they are the heart of the program. Drawn from excellent medical centers throughout the United States and from private practices, these physicians providethe program with a wide rangeof up-todate clinical experience and perspective that contribute to better patient care. The physicians involved in the 1985-1987 missions arelisted in Appendix A, and represent the following medical specialties: Internal Medicine Pediatrics Infectious Disease Cardiology Obstetrics /Gynecology Ophthalmology Endocrinology Surgery Gastroenterology Family Practice Geriatrics Allergy /Immunology Dermatology Neurology Pediatric Dentistry The participation of many excellent medical specialists undoubtedly has been a majorfactor in the acceptance of the Marshall Islands Medical Program by the population it serves. The percentof persons in the exposed and Comparison groups who appearfor the voluntary examinations remains high. For the current reporting period the annual acceptance rates were: Rongelap Utirik Comparison 1985 82% 92% 76% 1986 93% 92% 66% 1987 95% 90% 72%