Radiation Accidents and Their Management

Abstract

Radiation accidents have been a valuable source of information on radiation effects in man (1-9). As contrasted with studies of therapeutic radiation, the accidents usually involve normal people. Furthermore, the follow-up clinical and laboratory studies of accident victims are almost always carried out with great thoroughness. One disadvantage of the information derived from accidents is that the radiation exposure is usually nonuniform in distribution and penetration, and accurate dosimetry is often lacking. Most radiation accidents involve a sudden, brief exposure to penetrating radiation. In contrast, the exposures that may occur in the exploration of space are likely to include a large component of less penetrating radiations, although this situation can, of course, be greatly altered by shielding (10). In addition, there are the problems of the unfamiliar types of radiation, with their high linear energy transfer (LET); but perhaps most strikingly different from our previous experience will be the degrees of protraction involved. The exposures lasting for days or weeks will be considerably longer than those in most radiation accidents. Data in man for exposures of this duration are very meager. If astronauts receive high exposures from solai flares, these will probably be relatively short and thus more nearly approximate our previous expeiience. However, they may be superimposed upon a more prolonged, lower-level radiation exposure. Even though they are not directly applicable to the space pioblem, it may be helpful to consider what we know of previous radiation accidents. The most important information has to do with the responses to doses in the near-lethal and sublethal ranges. Higher, supralethal doses are rare and are unlikely to be encountered in space. In evaluating acute accidental exposures, we find that hematologic changes are not only the most serious clinical effects but also the best biological index of exposure dose. We have attempted to establish typical responses of the adult human being to three different doses of acute total-body irradiation-200 rads, 300 rads, and 450 rads. The curves presented here were established by averaging the results