Somatic Chromosome Aberrations Induced by Human Whole-Body Irradiation: The "Recuplex" Criticality Accident

The radiosensitivity of man has been a subject of great practical concern for many years. Unfortunately, information on this subject has been difficult to obtain, particularly in the area of hazards of radiation (1). The reasons for this are obvious. While a great deal of information has been accumulated on the radiosensitivity of the laboratory mouse, and while it is attractive to extrapolate directly from mouse (or other organisms) to man, such extrapolations always present some hazards; they must be made cautiously and their validity tested wherever possible. At present, chromosomal aberration studies appear to offer the best means of directly measuring human genetic radiosensitivity and of making such a test. Modern cytological techniques have made direct determination of aberration frequencies possible in mammalian cells. Somatic chromosome preparations, at least, may be made from readily available tissues. Cross-checking with other mammalian species, which can be used for experimental work in a manner impossible for human subjects, is easily done. Furthermore, a large body of information about chromosomal aberrations and chromosomal radiation response already exists (2). Starting with the pioneering work of Karl Sax in the 1930's, chromosomal aberration studies have become, in fact, one of the most thoroughly studied areas of radiobiology. The major features of chromosomal aberration production-doseeffect kinetics, dose-rate and dose-fractionation effects, and aberration loss and modification through cell division-have been understood for almost 30 years. A standard chromosomal aberration nomenclature has long been accepted by virtually every radiation cytologist in the world. The lack of suitable techniques for the preparation of mammalian material for cytogenetic analysis restricted early work largely to plants and invertebrate animals, but when adequate techniques did become available in the early 1950's, testing of the applicability of earlier data to