To The Editor: This letter is prompted by the recent publication of the forthright and authoritative comments on Radiation Hazards by Dr. John Caffey (Radiation Hazards in Diagnostic Radiology, Pediatrics 25:359, 1960).
The readers will be familiar with the evidence in the literature on the hazards, genetic and somatic, of ionizing radiation. It is, perhaps, pertinent at this time to mention some experimental data dealing with the mechanism of action of radiation in affecting intrinsic life processes. Only recently have tools for the quantitative and controlled study of these mechanisms become available.
One of these is the ability to grow human cells singly in vitro under carefully controlled conditions, which has made possible a study of the radiobiologic events which follow exposure of cells to ionizing radiation. Preliminary studies by Dr. T. T. Puck (The Action of Radiation on Mammalian Cells, Am. Naturalist 94:95, 1960) have already indicated the cell