RADIATION AND RISK: THE SOURCE DATA.

A likely impossibility is always preferable to an unconvincing possibility " Aristotle-from the "Poetics " With respect to physical and chemical components in the natural environment other than radiation, it would seem that Man has, through evolutionary processes, been adapted to function adequately over a rather broad range of exposure.Examples of this are carbon dioxide concentration in air, temperature, and barometric pressure.Observ ing this, we might be tempted to posit that Man's response to radiation exposure would be similar.However, as scientists we must stress that we do not know the effect of small exposures to radiation on human beings.We do not know whether such exposures are deleterious,of no consequence, or beneficial.It is perhaps true that more is known of Man's response to ionizing radiations than to any other self-inflicted pollutant of his environment.This is largely due to the experience of radiation injury resulting from early uses of x-rays and radioactive substances, particularly radium.From these early experiences and from studies on certain other groups of individuals subjected to high radiation exposures as a result of radiotherapy, nuclear weapons attack, or radiation accidents, a lim ited amount of information has been pieced together.Such information is almost entirely about the effects of large exposures and high doserates.If we are to make any progress in the difficult task of under standing the possible deleterious effects on the health of the population due to small exposures to ionizing radiation at low dose rates it is clear that much greater efforts at interdisciplinary studies are needed.Radiation physicists can measure human exposures to ionizing radi ations, physicians can advise on the appropriate indices of health, and statisticians can show us how to analyze available data in the most fruitful manner.It also seems clear that any conclusions we may reach as to the probable risks to human beings of low doseB of v