Dose and Biologica] Indicators 28 other services were rendered inoperative. These cities also ceased to exist as an entity. However, although acute radiation illness did cause a small fraction of the total deaths in the city. deaths from radiation-induced cancer could not be a factor because excess cancers did not begin to appear until the city was well along to being restored. However, even were there no latent period for cancer, the relatively minuscule num- 100 150 Imported Energy, € (kd) Fig. 10. The actual numberof solid cancers among the atomic bombsurvivors, plotted against imparted energy. permits one to obtain a value for the absolute amountof the agent energy that, on average, must be transferred to a population in order Se ee > wer eer oe to cause one excess cancer [4]. This value is nominally 3 kilojoules (kJ). The fact that in Figure 10 the ordinate is the absolute numberof cancers, and nota ratio that can be interpreted as a probability, points up the other problem with the function in Figure 9— it is not in accord with the levels of organization shownin Figure 1. Public health problems, such as are encountered in radioepidemiology, obviously involve a defined population, and the elements of that system are the number of persons exposed (system-element pair B, Fig. 1). Also, as was discussed earlier, whatis of interest is the fraction of the elements of the system dying, and whetherthis is severe enough to cause a quantal response in the system, i.e., the demise of the population of interest. Therefore, proper under these circumstancesis a plot of the same type shown in Figures 5 and 6, which provides the probability of the population showing a quantal response (dying) as a function of the severity of effect. Such a plot is shown in Figure 11. Although it may seem strange to speak in terms of entire populations or societies dying as a result of the killing off of large fractions of the human elements comprising the society, history is replete with this occurring as a result of wars, epidemics and other unknowncauses. During World WarII, Tokyo ceased to exist as a city because of mass carpet fire bombingofthe entire area. Similarly, with Hiroshima and Nagasaki a large fraction of the population was killed outright by the atomic bomb, and all sanitary and Moar al 4 po for hos boc Fo Discussion and Conclusions From the above discussionsit is clear that biological markers are not only useful. but are 3 50 Populations Dying, % 0 bers of cancer deaths would have precludedit from being a health problem that might threaten the continued existence of the two cities involved. If radiation-attributable cancers could have no effect under these extreme conditions of high-dose and dose rate, clearly they cannot constitute a significant public health problem with the low level radiation now encountered in routine radiation protection practice. Thus low level radiation exposure is not a medical problem atall, and a relatively insignificant public health problem. —— All Lethol Effects Radiation induced . ya Concer Deoths o 0 + 0.5 —| 1.0 Severity of Population Effect (deaths) Fig. 11. Plot showing the percent of populations, e.g.. cities. dying. as a function of the severity of injury to the cities as measured by the number of persons killed. With reference to Figure |. here the elements are people and the system is a city. Notice that induced cancer would have played no role in the demise ofthe cities, even were there no latent period. This lack of importance of cancer as a public health hazard under even these high-dose/high-doserate catastrophic conditions indicates that. with small amounts of radiation (low level irradiation), it can constitute only a relatively trivial public health problem. ne ity on tic or ab pr pl “g or se th: Sp tu as H: **]