Effects of Low-Level X Radiation on Chromosomes

¹ School of Dentistry, Department of Oral Radiology, University of California at Los Angeles, The Center for the Health Sciences, Los Angeles, California

This study investigated the effects of low doses of X radiation on chromosomes in mammalian epithelium exposed in vivo. The everted cheek pouch of Chinese hamsters was irradiated with 0.25 R, 2.9 R, and 5.4 R. Two hours after exposure, the pouches were biopsied and the tissue prepared for chromosome study. Analysis included the determination of the number and types of lesions in the chromosomes, including breaks, deletions, and exchanges. All doses of radiation produced significant amounts of chromosomal damage. The relationship between the number of aberrations per 100 cells and the exposure level was found to be linear but not directly proportional. The coefficients of aberration production were inversely related to dose level. Other work on radiation-induced chromosome aberrations has indicated a lack of a threshold phenomenon down to the 5 R level; the present data extend this dose level down to the 0.25 R. Although the dose levels of X radiation used in this study correspond to those used in dental radiography, the clinical significance of the results remains to be elucidated.