OFF-SITE MEDICAL ACTIVITIES, NEVADA TEST SITE and the MEDICAL LIAISON OFFICER NETWORK: A HISTORICAL REVIEW E, van der Smissen, M.D. U.S. Public Health Marine Hospital, Galveston, Texas and Maxwell E. Kaye, M.D., D.P.H.* ABSTRACT The "off-site" was originally defined as "that area surrounding the Nevada Test Site (NTS) for a radius of about 300 miles." Prior to 1954, the off-site radiological safety activities were conducted by the Atomic Energy Commission, In 1954, the Public Health Service was given the responsibility for off-site monitoring, and, in addition, a physician was also on temporary assignment. This physician, in addition to functioning as a monitor, also functioned part time as a physicial liaison in regard to possible or alleged radiation injury. Medical concern was based upon two crude guidelines: (1) possible radiation “overexposure” based upon extrapolation from surface and air radiological monitoring; and (2) determination of actual radiation injury based upon signa and symptoms among people alleging radiation injury. The area of concern expanded to 13 areas surrounding the Nevada Test Site, and in 1956, the first Medical Liaison Officer Network (MLON) was initiated. Over the years, MLON increased to a point where there was a representative from every state in the Union; the area of concern expanded to include the entire United States, parts of the South Pacific, Hawaii, and Alaska; and sophisticated methods of evaluation were added--urine sampling, thyroid scanning, blood counts, and whole-body counting. Epidemiological studies were initiated on body burdens of radionuclides and certain disease clusters. *National Environmental Research Center--Las Vegas 17