Healih Physrcs Vol. 61, No. 3 (September). pp. 4OL-404,1991 0017-9078/91 $3.00 .oO+ Printed in the U.S.A. 0 1991 Health Physics Society Pergamon Press plc Forum CONCEPT OF A “IAFETIME DOSE” OF 350 mSv I. V. Filyushkin Institute of Biophysics, 46 Zhivopisnaya, Moscow, D- 182, U.S.S.R. Abstrucf-After the Chernobyl accident, a number of radiation protection criteria for the early and intermediate phases of the accident were set up by the authorities to protect the public in affected areas. For the late phase, an intervention level of 350 mSv over a lifetime, the so-called 350-mSv concept, has been recommended by the National Council on Radiation Protection and Measurements (NCRP) in the USSR. This concept has been strongly criticized by opponents in the affected republics as being far too high and therefore inhumane. However, a lifetime dose of 350 mSv would impose on an individual an average annual risk of the order of y-’, which is lower than the annual individual risk due to nonradiation causes prevailing in many areas in the USSR. The basic radiation protection principles for nuclear accidents as recommended by the International Commission on Radiological Pro- tection (ICRP) and the International Atomic Energy Agency (IAEA) are at present very difficult to apply in the USSR because the concepts of risk and acceptable risk are rejected categorically. If, however, principles of justi- fication and optimization had been used, the result might have shown that the present lifetime dose limit of 350 mSv, as an intervention level, is actually too low. INTRODUCTION The discussion of 350 mSv as a lifetime dose, how- ever, is questionable, at least as long as its adherents con- BEFOREthe Chernobyl accident there had been no nuclear tinue to hold outmoded views regarding our hy- accident in the world that had resulted in heavy, long- giene. Exactly which principles ofour approach to hygiene term contamination of rural areas populated with as an element in our public health arrangements have hundreds of thousands of people- Not surprisingly, there become out of date and make the whole system unac- was no available international guidance on radiation pro- ceptable as ajustification for a lifetime dose hopefully tection criteria for dealing with such a long-term situation. be apparent from what is discussed below. H ~ ~ Therefore, the National Council on Radiation Protection one thing be noted: The criticism ofthe 350-m~v and Measurements (NCRP) Of the USSR recommended value that has recently been heard has not been accom- a lifetime dose limit (LDL) of 350 mSv as an intervention panied by any well-substantiated proposa~(i.e., of an al- criterion for countermeasuressuch as relocation of people ternative value) by its opponents that would Seem from contaminated areas. The projected lifetime doses to and acceptable. This is too, however, Comply with the limit would include doses to which the since the same principles that have made our public by- population had been exposed since 26 986 and giene of questionable value are, for that very reason, also were to be considered the sum of internal and external a powerful tool in the hands of those who would cate- doses accumulated during 70 Y of life. If projected doses gorically reject any dose as acceptable that is not equal to were expected to exceed this limit, countermeasureswould zero. be introduced. Under the terms that are typical of the USSR’s ap- The proposal of the 350-mSv lifetime dose limit Cre- preach to hygiene, no established dose limit could be re- ated a heated discussion in those republics of the USSR garded as anything other than safe. The 350-m~vlimit affected by the The Of LDL/ 70 does not fall in this category, if only because no such limit = 5 mSv/y was compared to the International COmmis- really exists: The effects of radiation have no threshold sion on Radiological Protection (ICRP) dose limgt of 1 according to the concepts of modern radiobiology. Thus, mSv/y for the population, and on this ground the lifetime we can only try to justify some level of exposure that is dose limit was claimed to be far to0 high and even in- not in the currently accepted Sense but that might humane. nevertheless be acceptable in accordance with specific cri- teria. -- A level exceeding what is “safe” (according to those (Manuscript received 12 Dclober 1990; revised manuscript received arbitrary criteria) would be unacceptable and would ac- 6 March 199 1, accepted 21 March 199 1 ) cordingly call for intervention, One of the intervention 40 1 402 Health Physics September 1991, Volume 61, Number 3 measures designed to prevent violation of the acceptable (of any and all groups of people) is based consists of lim- limit (but certainly not assuring any unattainable “ab- iting the risk (probability) that such effects will occur to solute’’ safety) is evacuation of the population from the the lowest possible level achievable by modern technical affected region. Indeed, any proposed limit should be re- and social means. This is the ALARA (as low as reason- garded only as an intervention level, and the 350-mSv ably achievable) principle, and it was instituted in a place lifetime dose is no exception. This concept may seem where the economic mechanisms and infrastructure of vague or undefined, but only from the standpoint of the society (including public health) are indeed placed at the approach to hygiene by scientists in the USSR, which, service of individuals. unlike the rest of the world, does not recognize such con- cepts. This lack of recognition makes it impossible to jus- RADIATION PROTECTION PRINCIPLES tify any lifetime dose limit in terms of knowledge acces- IN THE USSR sible to us at present. The principles underlying hygiene in the USSR have RADIATION PROTECTION PRINCIPLES always been based, and continue to be based, on uncon- ditional recognition of a threshold for inducing all types Where our own radiation protection principles fail, of effects and an equally categorical rejection of the ex- it becomes acceptable to fall back on the experience of istence of any risk from low levels of exposure. This prin- the rest of the world. In 1977, the ICRP espoused these ciple is intended to apply to all harmful agents present in goals (ICRP 1978): “The purpose of radiation protection the environment: “Any departure from the threshold must be to prevent harmful nonstochastic effects (purpose principle inevitably leads to adopting the concept of ‘ac- 1 ) and to limit the probability of occurrence of stochastic ceptable risk’ . . . notions about ‘socially acceptable risk‘ effects to levels which can be considered acceptable (pur- stand in contradiction to evolutionary theory and to the pose 2) .” principles of public health in a socialist society” (Izmerov The world community accepts these purposes gen- et al. 1984). erally in the same way, regardless of the group of people From a scientific viewpoint, the above quotation, exposed to radiation effects and regardless of the source like other similar ones, is a piece of nonsense. We dem- of the radiation. onstrated this repeatedly in previous publications (Fil- Nonstochastic effects have a threshold. With regard yushkin 1983; Filyushkin and Petoyan 1988). However, to the aim of preventing such effects, the validity of the that does nothing to diminish the administrative weight 350-mSv lifetime dose limit should not raise any doubts these ideas have brought to bear: Any public health worker after the international study carried out by the ICRP in a socialist society has only to look at the list of authors ( 1987) reporting the consequences of medical exposure in Izmerov et al. ( 1984)to realize that the principles they to radiation. From this work it is clear that at an annual stated up to 1984 would be put into effect without ques- dose limit of 5 mSv, nonstochastic effects do not occur, tioning. even with a lifetime exposure at this rate-and even as- The rejection by those in charge of administering suming a number of violations of the dose limit. We can public hygiene in our country of any effects (or risk) due be quite confident in saying that justification of the above to low levels of harmful agents will clearly not have done “concept” has not, in fact, gone far beyond the limits set anything to reduce the actual effects of such agents on by multiplying 5 mSv y-’ by 70 y. The author points out healthy people. Moreover, this approach has made it im- that a “concept” should normally imply more than simply possible to apply categories such as “risk” due to low levels multiplying two familiar figures together; in other words, of radiation, “risk control,” and “socially acceptable risk,” the concept of “lifetime dose” is merely an alternative which are the only categories that offer a realistic basis way of stating that the average annual dose limit will not for a rational limitation of risk, rather than simply ignoring exceed 5 mSv y-’ . it. Another unfortunate effect of this policy of ignoring Attaining the second of the two goals mentioned the true harm to health resulting from our long-ruined above for radiation protection does not yet have solid environment has been a sort of ecological illiteracy among roots within the framework of the “concept.” But then, the USSR population. it would be impossible to achieve this goal if we insisted All this has made it impossible to provide a con- on adhering to our domestic approach to public hygiene, vincing justification not only for the lifetime dose but for which still takes into account neither objective scientific any other radiation protection rules following nuclear ac- knowledge nor the abominable realities of the present state cidents; such rules are objectively aimed at limiting risk, of our environment. The first of these, objective scientific and this criterion simply did not exist among the principles knowledge, has long recognized the thresholdless action of “socialist” hygiene enshrined in law. Further, if a jus- of radiation, which can induce, even at the lowest possible tification cannot be made convincing, it is perceived as doses, late effects-mutagenic and cancer-inducing. It is invalid. This is, in fact, the source of many of the mis- important to remember that these effects constitute the understandings that still persist in connection with the only source of damage to individuals exposed to low ra- radiation protection standards applied after the Chernobyl diation levels (UNSCEAR 1977, 1986). accident, and the 350-mSv lifetime dose is no exception. The second element on which radiation protection To apply in the USSR the ALARA principle devel- A “lifetime dose” of 350 mSv 0 I. V. RLYUSHKIN 403 oped in the West is not easy. For example, it would surely The approach proposed appears unscientific or, at prove unacceptable to apply the logic of a benefit-harm the very least, unsuitable from a medical point of view. (cost-benefit)analysis (ICRP 1985). This type of analysis This is perfectly natural; after all, an “acceptable” radia- compares the benefit obtained by applying measures to tion risk can be justified only in terms of social categories protect a group of people-for example, resettlement- that must not only consider the production potential and with the costs required to implement those measures. If resources of the country but must also be consciouslyper- the level of the risk to be avoided is too low (e.g., a low ceived as meaningful within the framework of the coun- intervention level), then the indirect harm accruing from try’s economy and its political system. In our present sit- excessive expenditure of resources outweighs (even for uation, this last factor is obviously very important. Who the group to be protected) the immediate benefits of re- among us has not been placed in some socially advantaged settlement. From here we arrive at what is called the “op- category conferring, for example, the right to a house or timal” intervention level, where benefit and harm balance a hospital bed simply because of the situation in which each other perfectly. we find ourselves. It would be inhumane to set a lifetime This logic requires a thorough knowledge of the dose so high that it placed the victims of the accident at country’s economic mechanisms, and this is something the bottom of the ecological rank and file. Evaluations of even our leaders cannot boast of. It also assumes that due other kinds are perhaps rather less obvious, but where allowance will be made for benefit accruing indirectly to would they be, in fact, if the 350-mSv lifetime dose were all people (including those requiring protection) from adopted? savings realized on radiological protection measures. At The coefficient of radiogenic cancer risk resulting this point we need confidence in the social institutions of from the exposure of the population to large radiation the country, but what person who has suffered from a doses at Hiroshima and Nagasaki has been assessed at nuclear accident is likely to believe that economic re- about 0.042 deaths per Sv according to the “absolute” sources allotted for his protection will be spent in his in- risk model (UNSCEAR 1988). Extrapolation of this fac- terest and not get lost in an inflated budget. tor to low radiation levels requires a correction (NCRP 1989), the so-called dose rate effectiveness factor (DREF), THE RISK COMPARISON APPROACH to reflect the decrease in the risk coefficient for low dose rates of low-level radiation. This dose rate effectiveness Also possible, however, is an approach based on factor has been assessed variously at 2- 10 (UNSCEAR comparing the risk among the group requiring protection 1988), 3 (NCRP 1989), or not less than 5 (Filyushkin et with a risk already in existence among some comparable al. 1988). Consider, for example, a DREF = 4. The action group. This is, for example, the basis on which ICRP Pub- of other harmful factors that can exercise a synergistic lication 26 ( 1978)justified the dose limit of 50 mSv y-’ effect along with radiation is considered by applying the for occupationally exposed persons. The calculated ra- so-called “relative” risk model (UNSCEAR 1988). The diation risk derived from this dose limit proved to be 1 upper boundary will be a doubling of the risk coefficient in 10,000 y - l , which corresponds to the traumatic risk compared to the one derived from the “absolute” risk prevailing in the safest branches of industry. model. The selection of a group comparable to those who The risk coefficient applicable to a situation in which have suffered from the Chernobyl accident turns out to the normally accepted principles in the USSR apply will be simpler than it might seem at first. We have only to thus be 0.042 X 2/4 N 0.02 per Sv. For a group-averaged recall that the Chernobyl catastrophe, for all its unique dose of 350 mSv over 70 y (or, on average, 5 mSv per scale and consequences, did not create but merely enlarged year), the excess mortality rate due to radiation-induced the ecological disaster zone that has been encompassing cancer would be no more than 10 cases per 100,000 pop- our temtory for a long time. ulation per year. However, 350 mSv is not an average In the period 1981-1985, mortality from malignant lifetime dose but a dose limit. If the limit were observed, tumors was reported as 1 50 cases per 100,000 population the actual average dose would be several times less. Ac- per year (Dvojrin et al. 1988). If we accept figures that cordingly, anticipated mortality from radiation-induced indicate that, in our ecologically damaged cities, cancer cancer would not be 10 cases per 10 per year but much mortality is at least 30%higher than this (Buldakov 1991) , lower, corresponding to the actual average dose. we realize that the technogenic cancer risk alone in these This means that the 45 deaths per lo5 population places will be at least 0.3 X 150 = 45 cases per 100,000 per year characteristic of our ecologically (or, to be more per year. All people living in such ecological conditions precise, chemically) damaged towns would be compara- (and there are tens of millions of them) need an improved ble, according to this criterion, to a lifetime radiation dose environment. And what benefit would be due those who of 1.5-2 Sv or higher. Similarly, residents in the merely fell victim to the accident if the lifetime dose limit of 350 “gassed” regions and towns (let us say Moscow) would mSv were, in fact, accepted and implemented? Where correspond to at least 0.6- 1 Sv, but needless to say, there would they be ranked in the three categories so familiar are no plans to “relocate” towns with a ruined environ- to us: the general population, those who warrant special ment. The most we can hope for is some improvement consideration, and those who are singled out for special in the situation, and even that is obviously not going to treatment even among this last group? come about in the near future. Hence, all that our cus- 404 Health Physics September I99 1, Volume 6 1, Number 3 tomary social criteria would seem to suggest is that 350 of radiation effects, i.e., the existence of effects from mSv as a lifetime dose limit would mean weighting the harmful factors operating at “low” levels that have plagued population very definitely toward the socially privileged our environment for a long time and that, in a sense, have in regard to improvements in ecological conditions. brought about our present lamentable public health sit- As shown, we have used a single indicator-techno- uation. genic cancer risk-as our measure of ecological misfor- tune. However, a complete evaluation would need to CONCLUSION consider other no less important indices of medical risk such as mutagenesis and teratogenesis. But if radiation or Based on the analysis of the public health situation chemical exposure results in equal carcinogenic risk, there prevailing in the USSR as well as on international rec- are weighty reasons to believe that genetic and teratogenic ommendations in radiation protection, the following harm from the latter would be far more considerable: conclusions on setting intervention levels for protecting Contrary to popular belief, radiation is a comparatively the public after the Chernobyl accident have been drawn: “weak” mutagen. Accordingly, if these indices were also considered in our evaluation, the results would shift even 1. Radiation regulations, including intervention more definitely toward “chemical” damage to the envi- levels, have the purpose of limiting radiation risk to a ronment. level considered acceptable in light of “social” criteria. Finally, comprehensive assessments of ecological 2. One way of establishing and justifying an ac- conditions, whether good or bad, require reliable regis- ceptable level of radiation risk is to compare it with more tration, analysis, summarization, and publication of ep- general ecological conditions in the country, for example, idemiological data on the indices of congenital pathology levels of regional medical risk due to environmental in children-data at least as thorough and complete as chemical contamination. those collected for cancer statistics. But this is still some- 3. Taking these considerations into account, we thing for the future. Until quite recently, our common conclude that the lifetime dose limit of 350 mSv, as an and communal approach to public hygiene treated this intervention level, actually may be far too low, in contrast material as “confidential”-in much the same spirit as to the notion that has gained credence among the public the blind principles that rejected the thresholdless nature that it is far too high and therefore “inhumane.” REFERENCES Buldakov, L. A. Multiple regression analysis of cancer incidence and quantities in use by ICRP. Oxford Pergamon Press; ICRP around nuclear plants. Sov. Atomic Energy 3; 1991 (in Rus- Publications 41 and 42. Translated from English by Moiseev, sian). A. A., eds. Moscow: Ehnergoatomizdat; 1987. Dvojrin, V. V.; Tserkovnyj, G. F.; Gulaya, V. I.; Maksimova, Izmerov, N. F.; Kasparov, A. A.; Sanotskij, I. V.; Afanas’eva, V. P. Morbidity due to malignant neoplasms among the pop- P. F.; Sanin, B. M.; Suvorov, G. A. Methodological questions ulation oftheUSSR. Probl. 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