IS ALL NUCLEAR RADIATION HARMFUL

摘要

An analysis is made of available experimental results on the longevity effects of chronic low-level radiation upon animals. It is shown that a statistical average life-lengthening effect occurs at chronic life-time radiation exposure levels below about 2-5 rad/week;for higher exposures, a life-shortening effect is observed although the data do show variations among animals. Similarly, available data on chronic internal exposures resulting from injection of radioisotopes show that for such materials of interest as plutonium and uranium statistical life-lengthening effects also occur for comparatively low injections where higher injections produce life shortening. The principal sources of human data are statistical studies on the longevity of radiologists, and these also indicate an apparent greater life expectancy for this group as compared to physicians in general. It is noted that available data do not permit unequivocal determination of the over-all genetic effects of low levels of radiation, primarily because the data do not clearly indicate environmental selection principles. Some of the philosophical bases involved in evaluating the over-all somatic and genetic effects of low levels of radiation are briefly discussed.