Measurement of Low Levels of X-Ray Mutagenesis in Relation to Human Disease

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 83; no. 13; pp. 4839 - 4843
• Main Authors: Waldren, Charles, Correll, Laura, Sognier, Marguerite A., Puck, Theodore T.
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.07.1986; National Acad Sciences
• Subjects: Animals; Biological and medical sciences; Caffeine - pharmacology; Cell Survival - radiation effects; Chromosomes; Chromosomes, Human - radiation effects; Cricetinae; DNA Repair - drug effects; Dose-Response Relationship, Radiation; Dosimetry; Fundamental and applied biological sciences. Psychology; Genetic mutation; Human genetics; Humans; Hybrid Cells - radiation effects; Medical genetics; Molecular and cellular biology; Molecular genetics; Mutagenesis; Mutagenesis. Repair; Mutagenicity Tests - methods; Mutagens; Mutation - drug effects; Mutation - radiation effects; Radiation dosage; Radiation genetics; Somatic cells; X-Rays; Human; Measurement; Mutagenesis; Induction; Low dose; Critical study; Tumor; X ray; Method
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.83.13.4839

We previously demonstrated that conventional methods for measurement of mutagenesis in mammalian cells are subject to serious error that causes underestimation of environmental contributions to cancer and genetic disease. This error has been corrected by use of somatic cell hybrids containing a single human chromosome on which the marker genes are carried and by using doses of mutagenic agents so low that little cell killing occurs. This method permits direct measurement of the effects of low doses of radiation and other mutagens without resort to the controversial extrapolation procedure customarily used to estimate effects of doses in the neighborhood of actual human exposures. The new data demonstrate that the true mutagenesis efficiency at the low doses of ionizing radiation that approximate human exposures is more than 200 times greater than those obtained with conventional methods. This methodology also permits evaluation of localized mutations, large and small chromosomal deletions, and nondisjunctional processes and can be used for mutagens that need metabolic activation as well as for cooperatively acting agents. The two opposing classical views that in mammalian cells extrapolation to low doses of x-radiation is linear, on the one hand, or involves a threshold, on the other, are both demonstrated to be incorrect at least for the conditions here considered. The actual curve exhibits a downward concavity so that the mutational efficiency is maximal at low doses. These data may have important implications for human health.