Symposium on Developments in Radiation Protection.
by Pr Klaus Becker, Berlin
Vice President of Radiation Science & Health
Boothstr. 27, D-12207 Berlin
Published in ATW (Journal of the German Nuclear Society), January 2002
An elder statesmen in radiation protection, L. S. Taylor (former NCRP Chairman, ICRP member, etc.) already stated in 1957: "Radiation protection is not only a matter of science. It is a problem of philosophy, morality, and the utmost wisdom". Later he said that the use of the LNT model to calculate health effects of low-level radiation is a "deeply immoral use of our scientific heritage." This, to some degree, already summarizes the results of an international symposium of the German Nuclear Forum on the presence and future of radiation protection which took place in Munich Nov. 28/29, 2001. About 85 specialists from ten countries and several continents attended.
During the opening evening, the German Nuclear Society awarded its Honorary Membership to another elder statesmen, in this case of nuclear energy and the fuel cycle in Japan, namely Dr. Y. Akimoto from Tokyo. He is Chairman of Mitsubishi Materials Corp., President of the Japanese Central Research Institute of the Electric Power Industry, which also operates a new Low Dose Research Laboratory, etc.. It was a fitting introduction to the symposium that, in his comprehensive acceptance speech, he also dealt in detail with the important role of the low radiation dose issue in the public acceptance of nuclear energy. He stated that "ICRP created a false myth, misleading the public because its basic philosophy took on a life of its own. This makes people believe that there are no safe limits, there is no guarantee of safety possible, and the general public can never be satisfied . However, it is well known that a poison can easily become a medicine depending on the dose, and that there is clear evidence of benefits of low-level radiation, known as hormesis."
As two or three of the invited papers will also appear in this issue of atw, the following report will be primarily restricted to the other presentations, and some of the thought-provoking and sometimes controversial discussions, involving many well-known participants such as A. Kaul, former president of UNSCEAR, the German Radiation Protection Institute BfS, ICRP member, etc.; "Mr. Nuclear Safety of Germany" A. Birkhofer, and many others. The symposium was opened by Dr. Krebs, President of the German Nuclear Society. He quoted Ch. Streffer, the new German member of the ICRP main commission, from a recent lecture at the Nuclear Forum in Berlin in October with the statement that the linear dose-response concept, and the assessment of small radiation doses in relation to the wide variations in natural exposures has, unfortunately, not yet been communicated to the public so far. He also pointed out that the radioactive emission of nuclear energy in Germany has been reduced by two orders of magnitude during the past three decades, and cannot be graphically shown as a contribution to total population exposure any more. "A dose, whether from good mother nature or useful nuclear energy, will have the same effect."
In his following introduction, K. Becker pointed out that 1987 concepts and state of scientific knowledge reflected in ICRP 60, which is the basis of the new German Radiation Protection Regulation following legally binding EU regulations, urgently need updating, because scientific progress is far ahead of slow regulatory procedures. He said that the acceptance of clean, safe and economical nuclear energy and radiation uses in medicine, research, etc. including such aspects as decommissioning, remediation, waste management, and overground radon regulations are all related to the low dose issue. Political and economical factors have, unfortunately, also a strong influence on radiation protection politics. He stated that health physicists should care less about measuring doses in the Microsievert and activities in the Millibecquerel range up to three digits more sensitively, more accurately (and usually much more expensively), and quoted R. N. Proctor from his 1995 "War on Cancer": "The persistence of controversy is often not a natural consequence of imperfect knowledge but a political consequence of conflicting interests and structural apathies. Controversy can be engineered; ignorance can be manufactured, maintained and disseminated." This obviously also applies to some aspects of radiation protection in Germany.
The important opening lecture by ICRP-Chairman R. Clarke is printed in this atw issue (as well as is the next issue of "Strahlenschutzpraxis" with a different audience), and thus does not require detailed reporting. His main point was to prevent in the future obvious abuses of Collective Dose outside some special applications such as comparing maintainance activities in NPP. Doses of interest for risk should be defined in the region of a few mSv/y, and "differential equations should be replaced by common sense." There is a shift for the next edition of ICRP 60 to "egalitarism", and of making more use of natural background and its substantial fluctuations as a guideline for limit-setting. However, the LNT hypothesis remains to be the admittedly not really verifiable, but conservative and administratively well-established cornerstone of ICRP philosophy. Unfortunately, there may be many years before more flexible and "progressive" ideas actually could enter regulatory practice .
The next presentation was by K. Henrichs, President of the German/Swiss Radiation Protection Society (FS), about the benefits and costs of the "new" German radiation protection regulations. His presentation also underlined the old and very good relations between the FS and the German Nuclear Society. He pointed out that its introduction was mandatory according to European laws, and discussions about the scientific basis etc., are not feasible any more, and continued with a detailed description of the differences between the old and the new regulations. With the already very high radiation protection performance level of the German nuclear industry, the new regulations would by no means influence the current actual professional or population exposure levels, but create a multitude of additional administrative measures and expenses in the order of 500 mill. EUR within the next years (not including decommissioning, waste management, and so on).
Such expenses are difficult to quantify, e.g. regarding new controls of various consumer goods, construction changes in medical practices, natural occurring radioactive materials (NORM), new administrative procedures, less career opportunities for women, and remaining open questions including the simple question of how to define "environment". On the other hand, the new regulation has the advantage that some measures including decommissioning could be planned on a more legally secure basis and so also prevent or reduce some of the costs, reduce patient exposures, etc.
R. E. J. Mitchel, head of the Radiation Biology and Health Physics Branch of the Chalk River Laboratory in Canada, presented an excellent summary of decades of research on radiation biology of low doses mostly on the basis of cell and rodent experiments. According to his experimental results, the predictions of the LNT hypothesis (every dose, no matter how small, carries with it some risk; risk per dose unit is constant, additive, and can only increase with dose; and biological variables are insignificant compared to dose) are false, and he experimentally demonstrated why this is so. To quote a few sentences from his summary:
"Low dose-rate exposures stimulated the cells to increase their ability to repair broken chromosomes, such that the consequences of a second large exposure were reduced with the same result if the first exposure was 1 or 100 mGy The results show that low dose radiation induces an increase in error-free DNA repair competence. That repair system increases the probability of correctly repairing either radiation-induced or spontaneous DNA damage, or of triggering cell death if the repair is incorrect It seems clear that in normal cells and normal adult animals, low doses and low dose rate exposures to low LET radiation decrease rather than increase cancer risk Since there are no data in the literature that support LNT as a general hypothesis for cancer risk, and considerable evidence contradicting it, this hypothesis must be rejected. Some of the basic principles used in radiation protection such as ALARA are not consistent with the biology of low doses. It is time for a new risk-based approach to radiation protection, firmly linked to the actual biological responses." As a remark from the author of this report: These conclusions are remarkably similar to those by another well-known international radiobiologist, L. Feinendegen (Germany/USA), as presented at the 3rd Biophysics Workshop in Bad Schlema on Sept. 9. 2001, and many others.
Remark: This may be shortened if atw also prints the Mitchel paper.
A. Kellerer, director of the Institute for Radiation Biology of the GSF Neuherberg and the Radiobiology Institute of the University of Munich, presented an impressive view on recent insights into the radiological evaluation of the Chernobyl accident, the evaluation of neutron effects, etc. He pointed out that there have been serious underestimates in the neutron component in the Japanese bomb studies, and that there may indeed be a threshold for leukaemia around 200 mSv, but that the solid cancers indicate a more linear dose-response relationship. Perhaps even more importantly, he stated (also in the final panel discussion of the symposium), the unjustified claims of six-digit Chernobyl casualties, the nonsensical but expensive German efforts to "decontaminate" some cattle-food by-products of cheese production, with less activity than normal fertilisers ("Strahlenmolke"), etc. In particular, he emphasized that there are not only no demonstrable solid cancers (beside the child thyroid cases with 1-3 casualties so far) as a consequence of the Chernobyl accident, but also no increases in the most sensitive detector of radiation damage, namely childhood leukaemia.
P. Deetjen, Director of the Institute of Physiology and Balneology of the University of Innsbruck/Austria, provided some highly interesting (and generally little known) insights into the beneficial effects of radon, which is normally described and even "promoted" by governmental agencies as a dangerous residential lung cancer risk. He first pointed out some of the long-known biopositive effects of low level radiation. (Fig : Growth rate of paramaecia as a function of environmental dose rate, after Planel 1990). He then explained how, in various randomised clinical double-blind studies - which are "the gold standard of medical effectiveness" - by him as well as other groups in other radon treatment facilities, he became convinced about the positive effects of radon inhalation and bath treatments for a multitude of painful diseases such as arthritis, rheumatic problems, and Morbus Bechterew (Fig : Median pressure pain thresholds in kg/cm_ during, 2 and 4 months after treatment with radon and ordinary water (p<0.01 and 0.05, respect.)
He also described his and others research about the biochemical mechanism of such treatments on the very low dose equivalent levels of less than 10 mSv. As a conclusion of his presentation, he summarized (as L. Feinendegen had done also in some of his presentations) the current knowledge about the dose-effect relationship in the low dose, low dose-rate, and low LET area which is of most interest in practical radiation protection in a diagram.
Fig : Schematical diagram of biopositive and bionegative radiation effects as a function of dose, with the linear induction of radiation damage superimposed by the biological defense mechanisms.
The final presentation to this symposium by Z. Jaworowski, member and former president of UNSCEAR, Chairman of the Scientific Council of the Polish Radiation Protection Institute, etc., can also be read in full in this atw issue. Obviously, it offers a multitude of fascinating facts and insights into the aspects of the historical developments and future of radiation protection. To quote only one of his conclusions about the current legally required radiation levels: "Justification for such low levels is difficult to conceive, as no one has ever been identifiably injured by radiation while standards set by th ICRP in the 1920s and 1930s were in force, involving dose levels hundred or thousand times higher." He observes that the total radioactive waste produced by the nuclear power industry in 1997 (stored with extreme safety precautions) amounts to 0.9 km2 of the average, and highly mobile, natural activity of the worlds surface soil (after 500 y of cooling, all the worlds civilian nuclear waste would correspond to less than 4 km2). And non-eruptive volcanic venting processes produce the equivalent of about one third of all nuclear power waste radioactivity
During the final panel discussion, the spectrum of topics ranged from energy policies (with the recent 250 billion EURO estimate of the German Minister of Economics for the "ecological" reorganisation of German energy policy) all the way to medical physics. It was, for example, remarked that the U. K., with exactly the same life expectancy as Germany, needed seven times less population exposure for medical diagnostics (perhaps amortisation of CT units was less important there?), and how easy and inexpensive it would be to reduce population doses in the medical compared to the nuclear sector. A. Kaul pointed out that the German Radiation Protection Commission (SSK), under his chairmanship, already warned in 1986 against abuses of collective dose nationally and internationally in various publications.
Just to mention a few comments, questions and remarks (including some reflections by this author, which time pressure did not permit to articulate in detail): How about the natural differences in radiation sensitivity? Is the absence of genetic effects in humans, compared to mice, related to the better repair mechanism because of much longer generation periods and less offspring? How reliable are epidemiological studies in comparison with experiments on cells and animals? There was agreement with the suggestion to devote more attention to the media and public opinion multiplicators, addressing a wider audience with articles, letters to the editors, etc. There was also some discussion about the selective quoting habits of the LNT- supporters and LNT-sceptics. Not unexpectedly, some also articulated arguments in favour of maintaining LNT: It is presently "politically correct" in most Western European countries, simplifies bookkeeping, and administrators got used to it.
One expert (R. Hock) asked the interesting question: "Why do we need ICRP at all?" This is not easy to answer. Is it really reasonable to apply the same standards world-wide? Perhaps, with half of mankind living on less than two EURO per day, exploding AIDS rates and mass starvation, where a human life could in many cases be saved with a few EURO by vaccination or essential medicaments, is it only the very affluent nations which can afford the luxury of spending millions on one highly hypothetical earlier cancer case? As A. Kellerer put it in one of the final remarks: "If some fairy would offer me the option to completely abolish natural radiation, I would refuse."