Measurement of background radiation for epidemiologic purposes involves the use of technics capable of detecting geographic variation in exposure to external and internal natural sources of radioactivity at low levels. Methods for determining dose over a period of time are necessary and instruments are being developed. The methodology of this problem is analyzed. | Measurement of background radiation for epidemiologic purposes involves the use of technics capable of detecting geographic variation in exposure to external and internal natural sources of radioactivity at low levels. Methods for determining dose over a period of time are necessary and instruments are being developed. The methodology of this problem is analyzed. MEASUREMENT OF BACKGROUND RADIATION FOR EPIDEMIOLOGIC STUDIES Ascher Segall, . MEASUREMENT of background radiation for epidemiologic purposes implies the characterization of geographic areas according to the ionizing radiation of natural origin received by the residents. The dosimetric problems involved in estimating the average population exposure are relevant to both the planning of epidemiologic studies and the interpretation of results. This area of investigation poses the following problems: 1. The term "background radiation" incorporates a variety of independent and semi-independent natural sources of radioactivity which do not necessarily vary concomitantly from place to place or from time to time. The existence of multiple sources of irradiation complicates the search for geographic areas of widely differing dose levels, since any one source must be markedly elevated before appreciably raising the total dose. 2. Each of the various sources raises measurement problems of its own. Methods that are capable of detecting environmental variation of the order of that encountered in this country and that are at the same time suitable for 1660 the large-scale use required in epidemiologic studies are only now becoming available. 3. Estimates of geographic variation in the dose rate from natural internal emitters are currently based primarily on measurement of sources in the environment. Technics for determining the extent to which such estimates accurately reflect differences in the body burden are still in the process of development. 4. The optimal demographic unit for epidemiologic investigation is
