Tobacco Documents Online

HAZARDS: SCIENCE AND ITS LIMITS probability of such occurrences is zero-or at least, where the prevention of such mishaps relies on immutable laws of nature that can never fail rather than on the less than reliable intervention of electromechanical devices? Surprisingay, this approach to nuclear safety has come into prominence only in the past five years. Kare Hannerz in Sweden and Herbert Reutler and Gunter H, Lohnert in West Germany have proposed reactor systems whose safety does not depend on active interventions, but rather on passive, inherent characteli:,tics.16 Although one cannot say that the probability of mischance has been reduced to zero, there is little doubt that the probabilities are several, perhaps three, orders of magnitude lower than the probabilities of mischance for existing reactors. To the extent that such proposed reactors embody the principle of inherent safety, their adoption would avoid much of the dispute over reactor safety, the limits on nuclear accident liability contained in the Price-Andcrson Act, repetition of the Three Mile Island accident, and so forth. In short, such a technological fix enables one largely to ignore the uncertainties in any prediction of core-melt probabilities. The idea of incorporating inherent or passive safety into the design of chemical p,lants had been proposed by Trevor A. Kletz of the Loughborough University,of Technology in 1974, shortly after the disaster at the Flixborough cyclohexane plant, which killed 28 people." I suspect that one of the main consequences of the Bhopal disaster will be the incorporation of inherent safety features into new chemical plants; again, a way of finessing uncertainty in predicting failure probabilities. De minimis. A perfect technological fix, such as a totally safe reactor or a crash-proof car, is usually not available, at least at an affordable cost. Some low-level exposure to materials that are toxic at high levels is inevitable, even though we can never accurately establish the risk of such exposure. One way of dealing with this situation is to invoke the principle of de minimis. This principle, as Howard I. Adler and I suggested several years ago, argues that for insults that occur naturally and to which the biosphere has always been exposed and presumably to which it has adapted, one should not worry about any additional man-made exposure as long as the man-made exposure is small compared to the natural exposure.t8 The basic idea is that the natural level of a ubiquitous exposure (such as cosmic radiation), if it is deleterious, cannot have been very deleterious because in spite of its ubiquity, humans have survived. Moreover, we do not know and can never know what the residual effect of that natural exposure really is. An additional exposure that is small compared to natural background radiation should be acceptable; at the very least, its deleterious effect, if any, cannot be determined. Adler and I suggested that for radiation whose natural background is well known, one imay choose a de minimis level as the standard deviation of the natural background. This turns out to be around 20 percent of the mean background, around 20 millirems per year; this value has been used as the Environmelzial Protection Agency standard for exposure to the entire radio- chemical fuel cycle. Scientists know more about the natural incidence and biological effects of radiation than they do about any other agent. It would be natural, therefore, to use the standard established for radiation as a standard for other agents. FALL 1985 69

One can argue that an accident whose occurrence requires an exceedingly unlikely sequence of untoward ~e»ents may also be regarded as an act of G-i9d. This approach has been used by chemist T. Westermark of the Royal Institute of Technology in Stockholm. He has suggested that for naturally occurring carcinogens such as arsenic, chromium, and beryllium, one may choose a de minimis level to be, say, 10 percent of the natural background.19 Clearly, a dee minimis level will always be somewhat arbitrary. Neverthe- less, it seems to me that unless such a level is established, we shall forever be involved in fruitless arguments, the only beneficiaries of which will be the toxic tort lawyers. Could the principle of de minimis be applied in litigation in much the same way it may be applied to regulation-that is, if the exposure is below de minimis, then the blame is intrinsically unprovable and cannot be litigated? I would imagine that the legal de minimis may be set higher than the regulatory de minimis; for example, the legal de minimis for radiation could be the background (after all, the BEIR-III committee concedes there is no way of knowing whether or not such levels are deleterious). The regulatory de minimis could justifiably be lower, simply on grounds of erring on the side of safety. One approach may bc to concede that there is some level of exposure that is beyond demonstrable effect. This defines a trans-scientific threshold. A de minimis level could then be established at some fraction, say one-tenth, of this beyond-demonstrable-effect level. For example, if we take 100 millirems per year of radiation as the beyond-demonstrable-effect level for general somatic effects (damaging somatic cells as opposed to germline cells), which is the value according to the BEIR-III committee, a de minimis level could be set at 10 millirems per year. Of course, such a procedure would evoke much controversy as to what is the beyond-demonstrable-effect level or whether 10 is an ample safety factor. This example demonstrates, however, that at least in the case of low-level radiation, a scientific committee has been able to agree on a beyond-demonstrable-effect level. As for the safety factor of 10, this cannot be adjudicated on scientific grounds. The most one can say is that tradition of- ten supports a safety factor of 10-forexample, the old standard for public ex- posure (500 millirems per year) was set at one-tenth of the tolerance level for workers (5,000 millirems per year). Can the principle of de minimis be applied to accidents? What I have in mind is the notion that accidents that are sufficiently rare may be regarded somehow in the same category as acts of God and be compensated accord- ingly. We already recognize that natural disasters should be compensated by the society as a whole. One can argue that an accident whose occurrence requires an exceedingly unlikely sequence of untoward events may also be regarded as an act of God. Thus, the Price-Anderson Act could be modified so that, quite explicitly, accidents whose consequences exceeded a certain level, and whose probability as estimated by probabilistic risk assessment would be less than, say, I in I billion per year, would be treated as acts of God. Compensation in excess of the amount stipulated in the revised act would be the responsibility of Congress. The cutoff for either compensation or for probabilities would be negotiable, and perhaps it would be revised every 10 years or so. One not entirely fanciful suggestion may be to set any probability of the order of I in 10 million to I in 100 million per year to be a de minimis cutoff, this being the frequency at which the earth may have been visited by 70 1SSUES IN SCIENCE AND TECHNOLOGY

HAZARCS: SCIENCE AND ITS LIMITS the comel:arv asteroids that may have caused the extinction of species in past geologic eras. As in most such questions, identifying and characterizing the problem is easier tha n solving it. That the dilemma of the regulator and the toxic tort judge is rooted in science's inability to predict rare events cannot be denied. Getting lthe regulator and the toxic tort judge off the horns of the dilemma is far from easy, and my two suggestions-the technological fix and de minimis--are offered tentatively and with diffidence. Equaily obvious is the intrinsic social dimension of the issue. In an open, litigious democracy such as ours, any regulation and any judicial decision can be appealed, and if the courts offer no redress, Congress, in principle, can do so. These legal mechanisms are ponderous, however. The result seems to me to be a gradual slowing of our technological-social engine as we become more and mom enmeshed in fruitless argument over unresolvable questions. Wes',~ern society was debilitated once before by such fruitless tilting with Don Quixotian windmills. I refer of course to the devastating campaign against witches from the fourteenth century to the early seventeenth century. As ecolog~s,t William Clark has put it so vividly, society took it for granted dur- ing that period that death, disease, and crop failure could be caused by witches.x' To avoid such catastrophes, one had to burn the witches responsible for them--and consequently some million innocent people were burned. Finally, in 1610, the Spanish inquisitor Alonzo Salazar y Frias realized there was no demonstrated connection between catastrophe and witches. Although he did not prohibit the burning of witches, he did prohibit use of torture to ex- tract confessions. The burning of witches, and witch hunting generally, declined precipitously. I have recounted this story many times by now. Yet it still seems to me to capture the essence of our dilemma: the connection between low-level insult and bodily harm is probably as difficult to prove as the connection between witches and failed crops. I regard it as an aberration that our society has allowed this issue to emerge as a serious social concern, which in the modern context is hardly less fatuous than were the witch hunts of the past. That dark phase in western society died out only aft' er several centuries. I hope our open, democratic society can regain its sense of proportion far sooner and can get on with managing the many real problems we always will face rather than waste its energies on essentially insoluble, and by comparison, intrinsically un- important, problems. ® NOTES: I. This article was adapted from a paper delivered at a June 3-4, 1985. National Academy of Engineering symposium on "Hazards: Technology and Fairness." A report on that symposium will be published in book form by the National Academy Press. 2. William 1). Ruckelshaus. "Risk, Science, and Democracy," Issues in Science and Technology I (Spring 1985): 19-38. 3. U.S. Nuclear Regulatory Commission, Reactor SafetyStudt•: An Assessment ofAccident Risk in U.S. Commercrat Nuclear Plants (WASH-1400. NUREG 75/014) (Washington, D.C., 1975). FALL 1985 71

4. U.S. Nuclear Regulatory Commission, Risk .4ssessmenr RevieK• Group Report to the U.S. Nuclear Regulaton• Commission (NUREG/CR-0400) (Washington, D.C.. September 1978), vi. 5. "Repon to the American Physical Society by the Study Group on Light Water Reactor Safety," Reciexs oJAfodern Physics 47 (Supplement 1) (Summer 1975). 6. National Research Council, The Effects on Populations of Exposure to Low Levels of loni=ing Radiation: 1980 (BEIR-IlI), (Washington, D.C.: National Academy Press, 1980), 2. 7. National Research Council, The Effects on Populations ojExposure to Low Levels of lonizing Radiation: 1980 (BEIR-1I1), iii. 8. National Research Council, The Effects on Populations of Exposure to Low Levels of loni:ing Radiation (BEIR-II), (Washington, D.C.: National Academy Press, 1972), 2. 9. Bruce N. Ames, "Dietary Carcinogens and Anticarcinogens," Science 221 (Sept. 23, 1983): 1249, 1256-64. 10. John R. Totter, "Spontaneous Cancer and Its Possible Relationship to Oxygen Metabolism," Proceedings ojthe National Academy oJSciences 77 (April 1980): 1763-67. 11. Alvin M. Weinberg and John B. Storer, "On 'Ambiguous' Carcinogens and Their Regulation," Risk Analysis 5 (June 1985): 151-55. 12. National Research Council, The Effects on Populations of Exposure to Low Levels oj lonizing Radiation.• 1980 (BE1R-1Il), 287-321. 13. Alice Whittemore, "Facts and Values in Risk Analysis for Environmental Toxicants," Risk Analysis 3 (March 1983): 23-33. 14. John Ben-David, "Emergence of National Traditions in the Sociology of Science: The United States and Great Britain," Sociological Inquiry 48, nos. 3 and 4(1978): 209. 15. Trevor J. Pinch and Wiebe E. Bijker, "The Social Construction of Facts and Artefacts: Or How the Sociology of Science and the Sociology of Technology Might Benefit Each Other," Social Studies of Science 14 (1984): 401. 16. KAre Hannerz, Towards Intrinsicalfr Safe Light li•ater Reactors (ORAU/IEA-83-2(M) Rev.) (Oak Ridge, Tenn.: Oak Ridge Associated Universities. Institute for Energy Analysis, June 1983): Herben Reutler and Gtinter H. Lohnert, "The Modular High Temperature Reactor," Nuclear Technologr 62 (July 1983): 22-30. 17. Trevor A. kletz. Cheaper, Safer Plants or If •ealth and Sqfett• at Gi'ork: Notes on Inherenth Safcr and Simpler Plants (Rugby. England: The Institution of Chemical Engineers, 1984). 18. Howard 1. Adler and Alvin M. Weinberg. "An Approach to Setting Radiation Standards," Health Ph, vstcs 34 (June 1978): 719-20. 19. T. Westermark, Persistent Genoroxic I;'¢ues An .9ttempt at a Risk Assessment (Stockholm: Royal Institute of Technology, 1980). 20. William C. Clark, it'itches. Floods, and If onder Drugs: Historical Perspectives on Risk Management (RR-81-3) (Laxenburg, Austria: International Institute for Applied Systems Analysis, March 1981). 72 ISSUES IN SCIENCE AND TECHNOLOGY