Numerous examples of potential and real hazards are given. They all show that injury to personal health or the environment is a function not only of the toxicity (i.e. the lethality of a particular hazard) but of the level of exposure to the hazard concerned - in the words of the old maxim, the dose makes the poison.
Existing regulation is criticized for being based on a flawed application of a poor epidemiological methodology, where toxicity is the basis of regulation and dose tends to be ignored. Furthermore, some authors conclude that risk is a subjective phenomenon that cannot be eliminated through regulation.
Leading international expert authors and contributors
Mass-media launch on publication
Important new commercial and H&S area of interest
Whether the public or the environment is at risk is a commonly discussed question in numerous areas of public life, most recently and publicly with regard to issues like BSE, passive smoking and the dangers from pesticides in food production. It is therefore of great importance for everyone concerned with these issues - both policy makers and the public who may be subject to their decisions - to understand the basis on which 'risk' policy is made. The principle objective of this book is to highlight the uncertainties inherent in 'scientific' estimates of risk to the public and the environment resulting from exposure to certain hazards. Numerous examples of potential and real hazards are given. They all show that injury to personal health or the environment is a function not only of the toxicity (i.e. the lethality of a particular hazard) but of the level of exposure to the hazard concerned - in the words of the old maxim, the dose makes the poison. Existing regulation is criticized for being based on a flawed application of a poor epidemiological methodology, where toxicity is the basis of regulation and dose tends to be ignored. Furthermore, some authors conclude that risk is a subjective phenomenon that cannot be eliminated through regulation. Leading international expert authors and contributors Mass-media launch on publication Important new commercial and H&S area of interest
Front Cover
1
What Risk? 4
Copyright Page 5
Table of Contents 6
Foreword 8
Preface 11
Executive summary 17
Acknowledgements 19
Biographies 20
PART I: Methodology 26
CHAPTER 1. Thresholds for carcinogens: a review of the relevant science and its implications for regulatory policy 28
Summary 28
Introduction 29
The meaning of threshold and current applicationto policy 31
The scientific case for a no-threshold assumption 33
Scientific evidence for the existence of athreshold 37
Implications for policy 46
Some science policy issues 51
Conclusions 54
Acknowledgments 55
Appendix: How science contributes topolicy formation
56
References and bibliography 58
CHAPTER 2. Biases introduced by confounding and imperfect retrospective and prospective exposure assessments 62
Summary 62
Statistical approaches to confounding 64
Pathways of cause-effect events 65
Susceptibility bias 65
Detection bias 66
Transfer bias 68
Exposure bias 69
Reasons for problems 70
Acknowledgement 72
References 73
CHAPTER 3. Problems with very low dose riskevaluation: the case of asbestos 74
Summary 74
Introduction 75
Mathematical models and risk evaluation 76
Main strategies 79
The case of asbestos 82
A medical language exists and must be respected.Speaking more generally we must avoidpublishing in medicine that which is medicalnonsense. 88
Rejection of 'everything goes' is a pressing necessity in chronic human very low dose toxicology 91
Acknowledgements 92
References and bibliography 92
PART II: Science 96
CHAPTER 4. Benzene and Leukaemia 98
Summary 98
Introduction 98
Industrial use of benzene 99
Health effects: acute exposure 100
Health effects: chronic exposure 101
Leukaemia 101
The link between benzene exposure and leukaemia 103
Regulation of benzene 108
Quantitative risk assessment (QRA) 109
The US process of QRA 111
Epidemiology of industrially exposed workers 112
Conclusion 117
References 117
CHAPTER 5. Is environmental tobacco smoke a risk factor for lung cancer? 121
Summary 121
Introduction 122
Biological plausibility of current risk estimates 133
Bias and confounding 139
Confounding 153
Quantifying exposure 159
Pooling of risk estimates 161
Other potentially adverse health effects 164
Non–scientific considerations 165
References 166
CHAPTER 6. Beneficial ionizing radiation 176
Summary 176
Introduction 177
The linear hypothesis 178
Radiation hormesis 183
Experimental evidence 185
Epidemiological evidence 187
References 194
CHAPTER 7. Pollution, pesticides and cancer misconceptions 198
Summary 198
Myths and facts about synthetic chemicals and human cancer 199
References 213
CHAPTER 8. Interpretation of epidemiological studies with modestly elevated relative risks 216
Summary 216
Introduction 216
Role of bias 217
Selection 217
Misclassification 218
Confounding 219
Risk identification 220
Risk estimation 221
Conclusions 222
Acknowledgement 223
References 223
CHAPTER 9. The risks of dioxin to human health 226
Summary 226
Introduction 226
The mounting fears of dioxin and the accident at Seveso 227
Generation and occurrence 230
Intake of dioxins into the organism and elimination 231
Mode of action 232
Clinical manifestations of PCDD/PCDFs 233
Chronic toxicity 234
Carcinogenicity 235
Health risk assessments 239
References 239
PART III: Science policy 244
CHAPTER 10. Public policy and public health: coping with potential medical disaster 246
Summary 246
Introduction 246
The unexpected 249
AIDS 253
BSE 254
Perceptions and assessments of risks and uncertainties. 255
Public policy and public health: an examination of blame avoidance strategies 260
Conclusion 262
Acknowledgement 263
References 263
CHAPTER 11. How are decisions taken by government on environmental issues? 267
Summary 267
Factors influencing decisions on environmental issues 267
The role of science in determining environmental policy 269
Discussion of specific environmental issues 274
References 281
PART IV: Commentaries 284
CHAPTER 12. Should we trust science? 286
Summary 286
References 291
CHAPTER 13. The proper role of science in determining low-dose hazard, and appropriate policy uses of this information 292
Summary 292
PART V: Perception 298
CHAPTER 14. Mass media and environmental risk: seven principles 300
Summary 300
Acknowledgement 308
References 308
CHAPTER 15. Cars, cholera, cows, and contaminated land: virtual risk and the management of uncertainty 310
Summary 310
Cars and the risk thermostat 311
Risk: an interactive phenomenon 312
Problems of measurement 313
Reliable knowledge: risks perceived through science 316
Virtual risk - beyond reliable knowledge 320
Plural rationalities 321
Coping with risk and uncertainty: the doseresponse curve 322
BSE/CJD: should we follow a risk–averse environmental policy?
326
The Sydney Smith dilemma 328
Appendix 15.1 330
Appendix 15.2 332
Appendix 15.3 334
Glossary 340
About ESEF 343
Mission statement 346
Authors' addresses 348
Index 352
Preface
Science and the media
This book is about the likely health effects resulting from the emission of small quantities of potentially harmful toxins into the environment and how these substances should be controlled. Many such hazardous substances have been identified and many more probably exist. The particular substances under discussion were chosen because of their relatively high public profile – each has been, at one time or another, the subject of considerable media attention that intensified public fear.
Most of the hazards were newly identified at the time of this media attention, often because they were the subject of epidemiological investigations, or because new technology enabled measurement of toxins at lower concentrations than had earlier been possible. Some were always present but we were not aware of them or their effects, some are by-products of new technology. In most cases, the science of the alleged causal link between toxin and effect is still being formulated, so that an absolute answer to the question of whether a particular substance is a health hazard at the level at which it is commonly present in the environment – or even at much higher levels – is often not available. Frequently, this inability to satisfy curiosity gives rise to alarm and then to suspicion, so that informed debate is overtaken by fears of conspiracy.
Recent campaigns highlighting the apparent lack of public understanding of science have focused on educational programmes in schools and universities. However, most adults become informed about science and technology through the media. These campaigns have largely ignored this fact and there has been little critical analysis of the way that science is portrayed by journalists or of the relationship between the two influential social institutions of science and the media.
For most people, science is understood through the filter of journalistic language and imagery. This filter has changed considerably since science journalism really took off in the 1950s. In the early days, journalists were, in many respects, simply retailers of science, presenting neatly packaged information to readers. However, as the science writers themselves became more sophisticated, and the mood of the times changed, they became more critical of the science they were asked to interpret. By the 1960s journalists were discussing the mixed blessings of science, and by the mid-1970s the environ-mental and consumer movements had begun to speculate on the potential risks to human health from the products of technology. This speculation was further fuelled by several technological disasters: the Bhopal and Seveso chemical spills, the explosion of the space shuttle, ‘Challenger’ and, of course, the nuclear meltdown at Chernobyl. Since then there has been a tendency to welcome new discoveries, such as surgical breakthroughs, but to be highly critical of even the smallest environmental and public health threat.
Many scientists have been concerned that information from pressure groups is treated uncritically by the media. The ‘Brent Spar’ issue, where Greenpeace duped television producers with doctored video coverage, has awakened the electronic media to the problems of being spoon-fed news by pressure groups. Concerned for their image as much as anything else, the media in the late 1990s is attempting to find balance in scientific reporting.
Scientific objectivity arises from empirical testing of theories, which are revised in the light of new evidence and/or better theories. However, empirical testing is not the way that the media create objectivity. Journalists accept that it is not their role to achieve objectivity, but they are expected to approach the ideal of neutrality and unbiased reporting by balancing diverse points of view, by presenting all sides fairly, and by maintaining a clear distinction between news reporting and editorial opinion. However, this ideal is rarely lived up to. The media often fail to present an objective view; they can present a very selective sample of theories and empirical tests and often fail to interpret these correctly, misunderstanding the science and the statistics. And they do so because of prejudice, time pressure and ignorance. It often frustrates scientists that, for the media, balance becomes synonymous with objectivity. However, some scientists use this to their advantage, claiming that the majority view (which they propound) must be correct.
Balanced reporting by journalists is necessary but not sufficient if the public is to be accurately informed of the science relating to any particular scare. Of course, the ability of a journalist to balance a debate requires that he or she be aware of all relevant opinions. However, certain opinions may be contrary to a prevailing orthodoxy, political position or ideological hegemony, in which case there may be reluctance to raise dissenting opinions for fear of retribution against those holding this opinion. The worst examples this century were the debates on eugenics and Lysenkoism. Opinions which are not voiced in public will not be taken into account by the media and therefore only the perception of balance may be given, while the reality is considerably different.
The European Science and Environment Forum (ESEF) seeks to aid the debate by providing the media with rigorous analyses of current debates, bringing to the attention of the media and the public critical works in the scientific literature that may have been overlooked. Through books, briefings, speaking tours and conferences, ESEF members seek to preserve the integrity of science and to promote wider scientific literacy. This book is part of that effort.
Scientists often blame the media for exaggerating stories of alarm, but of course it is not just the media that like exciting ‘positive’ results. In a recent paper in the science journal Oikos (Csada et al. 1997), three Canadian biologists explained how research which is important, but not exciting or innovative, seldom makes it into the more prestigious scientific journals. Those journals rarely carry papers where the findings are largely ‘negative’. For example, a researcher might analyse the data relating to the link between pesticide residues in apples and bladder cancer, and conclude that his results indicated no correlation. One would think that his findings would be useful for those working in similar fields. But such results are not exciting, and thus the chance of the paper being published in a top journal like Nature is remote – at least, that is the conclusion of Csada et al. 1997., who analysed 1812 scientific papers published between 1989 and 1995, picked at random from 40 biology journals. Only 9 per cent of the papers contained ‘non-significant’ results; the figure was even lower for the most prestigious journals.
Given the pressure on university researchers to publish – and in good journals – the bias against publishing ‘negative’ results has some worrying implications. First, it is likely that hypotheses tested will be conservative, because positive results will seem more likely in such cases. More outlandish hypotheses – ones that might broaden the scientific picture – will not be entertained. Second, researchers are likely to select carefully the data in search of a significant correlation. If the chance of being published is increased by showing a positive result, researchers will be tempted to trawl through the data until they find one – ignoring any negative correlations they encounter on the way. Careers may depend on such things.
It is because even the much-vaunted peer review process is far from pure (see Feinstein’s paper) that debate in wider circles is so important. Imagine five identical epidemiological research projects analysing the links between pesticide residues and bladder cancer. Four find no correlation; one finds a correlation. If, because of publication bias, the latter project is published and the former research is ignored, the non-specialist scientist will become slightly worried about pesticide residues. A journalist with information only about the published study could unwittingly turn minor concerns into a grave, powerful discovery.
But, even if the above correlation did exist, the statistician’s caveat is worth remembering: association is not causation. Many fat people drink diet cola but this does not imply that diet cola causes obesity. Most people understand this but many other claimed correlations, especially those for which people do not have personal experience, can lead people to jump to the wrong conclusions. Of course, people do not often deliberately choose to make mental errors or to remain ignorant of highly relevant facts. Too often, though, we seize the first plausible explanation offered. Once we have formed a belief, we are inclined to dismiss contrary evidence. We like to tell ourselves that we are superior to the people who burned witches centuries ago but we are still prone to the same basic mental errors: seeing patterns where there are none, assuming cause where there is only coincidence, and creating widespread alarm from scanty evidence.
There is no simple solution either to the degree of misinformation in the public domain or to the process that leads to panic. However, providing more reliable information is likely to help. Indeed, many of the papers in this book present information concerning particular hazards that should allay some of those fears. Meanwhile, the papers by Adams and Sandman provide insights into the nature of risk and of public perception that scientists would do well to consider; as the BSE fiasco has...
Erscheint lt. Verlag | 2.12.2012 |
---|---|
Sprache | englisch |
Themenwelt | Studium ► Querschnittsbereiche ► Prävention / Gesundheitsförderung |
Naturwissenschaften ► Biologie ► Ökologie / Naturschutz | |
Naturwissenschaften ► Biologie ► Zoologie | |
Recht / Steuern ► Wirtschaftsrecht | |
Technik ► Bauwesen | |
Technik ► Elektrotechnik / Energietechnik | |
Technik ► Umwelttechnik / Biotechnologie | |
Betriebswirtschaft / Management ► Spezielle Betriebswirtschaftslehre ► Versicherungsbetriebslehre | |
ISBN-10 | 0-08-052100-2 / 0080521002 |
ISBN-13 | 978-0-08-052100-8 / 9780080521008 |
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