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Professor Anthony Seaton

Committee for Finance and Personnel

Damages (Asbestos-Related Conditions) Bill

Written Evidence from Professor Anthony Seaton


 Prof Anthony Seaton CBE,


Pleural plaques are benign lesions caused by past asbestos exposure and are not pre-malignant. They cause no symptoms to the individual, but are a marker of past exposure to asbestos. Anxiety may be prevented by careful explanation of their implications to the subject. This medical process is hindered by the implication of available compensation that they are indeed a significant medical condition. The numbers of individuals currently with pleural plaques may be as many as a million in England and Wales.

Negative implications of their recognition as a tortious condition are an overall increase in anxiety among asbestos-exposed individuals, a significant increase in radiation hazard to the population, an increase in the risk of anxiety related to unnecessary investigations and false positive results requiring further investigation, and increases in public expenditure in defending actions and investigating and treating anxious patients in the NHS. On the positive side, while those well people with plaques may receive a sum of money, law firms and expert witnesses may look forward to significant increases in revenue.

1. The House of Lords has accepted medical evidence that pleural plaques are harmless indicators of past asbestos exposure and not a cause of ill health. They have discussed in extenso the legal issues surrounding compensation for such a condition and have decided that there is no case in law for actions against employers for the condition. I have been asked for my opinion on this issue. My views are those of a physician and researcher who has made a prolonged study of the issues and has looked after many patients with asbestos-related conditions.

2. I agree with the decision of the House of Lords, which is based on generally accepted medical knowledge. Much of the argument revolved around the anxiety felt by individuals as a consequence of receiving information that they had plaques. For the reasons given below, I am of the opinion that this anxiety relates to inability of doctors to reassure patients about the benign nature of the condition in light of legal implications that it is a serious disease. The risks relate to asbestos exposure, not to pleural plaques, and such risks can now be quantified and put into perspective in order to inform and usually reassure the individuals concerned.

3. Asbestos causes a number of different conditions of the lung and its lining (the pleura), some serious and fatal, others less serious, and some trivial but sometimes alarming. The most serious such conditions, mesothelioma and lung cancer are widely known by the public to be fatal, while asbestosis is potentially disabling and fatal. The others, notably pleural plaques, pleural effusion and pleural fibrosis, though not fatal, are often confused in the public (and sometimes medical) mind as “asbestosis”. The least serious is the development of pleural plaques. This is however far and away the most common of all the asbestos-related conditions and thus has acquired important financial connotations to companies, lawyers and doctors as well as to workers, out of all proportion to its medical importance.

4. Mesothelioma is universally fatal, almost uniquely attributable to asbestos exposure and relatively common, occurring in some 2000 people per annum in UK. The risk of development is related to the dose of asbestos received (the product of exposure concentration and duration). Asbestosis is now rarely fatal, since its development requires a very high exposure and such exposures are historic in the West. It does however still appear in a slowly progressive or arrested form in some individuals with heavy past exposures and certainly can be disabling. Lung cancer is primarily related to cigarette smoking but asbestos exposure is a well-recognised risk factor that acts synergistically with smoking. These serious conditions are rightly compensable under civil law and the degree of disablement is assessable in the normal manner.

5. The pleural conditions other than mesothelioma differ in a number of ways. Pleural effusion is usually temporarily disabling by breathlessness and pain and may resolve into pleural fibrosis. It is worrying for the patient, since the alternative diagnosis the doctor considers is always mesothelioma and several investigations and ultimately the passage of time without worsening are necessary to exclude this fatal possibility. There is no dispute about compensation for this. Diffuse pleural fibrosis likewise may be confused with mesothelioma, requires investigation and causes anxiety. In addition, if it is sufficiently extensive it may cause pulmonary impairment and sometimes pain; any dysfunction may be measured easily by lung function testing. Again, compensation is not in dispute. In contrast, pleural plaques are medically trivial, cause no impairment and, until it was proposed by lawyers that they should attract compensation, caused no medical problems. They have now become big business for law firms (a Google search gives evidence of this) and an easy source of income for expert witnesses. Their unnecessary investigation by CT scanning has resulted in considerable radiation exposure of well people, sometimes at the instigation of lawyers rather than doctors.

6. I first became interested in industrial and asbestos diseases and their prevention as a junior doctor in Liverpool in the 1960s. In the United States, from 1969 to 1971 I concentrated mostly on coalminers’ diseases but in Cardiff, as a young chest consultant, I saw many patients with both coal- and asbestos-caused disease. My interest and knowledge of these and other conditions was such that I published my first book on the subject with my American colleague, Prof WKC Morgan, “Occupational Lung Diseases” in 1975. At that time and well into the 1980s the benign nature of pleural plaques was known to the medical profession. In pathological terms they are collagenous (fibrous) scars, usually on the under-surface of the ribs or on the diaphragm, on what is called the parietal pleura and almost always covered by an intact layer of normal lining mesothelium. They neither involve the lungs themselves nor impair its function. They are not pre-malignant. They were however known to be an indication of previous asbestos exposure and thus a confirmation of the story recounted by the subject. They indicate that some asbestos has passed through the lungs and reached the lung lining and has then been inactivated by a fibrotic reaction. By their limited extent and their position away from the lung, they cannot impair its function.

7. During my earlier professional career it was possible to deal with patients in whom pleural plaques had been discovered, almost always as an incidental finding consequential upon having a chest radiograph, by explaining that they simply meant that, as the person usually knew, he (rarely she) had been exposed to asbestos and that they did not imply the likelihood of any serious disease. As time passed, it became possible for chest physicians with suitable knowledge to explain any risk of other asbestos disease related to the exposures and to make a rough estimate of risk in relation to other likely conditions such as other cancer or heart attack. It was thus possible to reassure the person. A competent chest physician was therefore able to prevent a long legacy of usually unnecessary anxiety and allow the person to continue to lead his (almost always these people are male) normal life.

8. From a clinical medical point of view, matters changed when it was decided legally that individuals with pleural plaques became entitled to sue for injury and able to obtain financial compensation. Part of this acknowledged the presence of “anxiety”, an inevitable consequence of bad medical management forced upon doctors by the difficulty of explaining the benign nature of the condition when the law apparently says it is a disease, with implied serious consequences. The management of these individuals was thus handed over to lawyers who did not have a strong interest in reducing any anxiety. Since the House of Lords’ decision it has again been possible to manage such individuals according to established medical practice.

9. In making these comments, I should point out that I have appeared in Court in the British Isles and the United States on a number of occasions both for defenders and plaintiffs and have often written expert reports on asbestos cases. My and my colleagues’ research work over a lifetime has been devoted to prevention of industrial and environmental diseases and some has resulted in considerable benefits to working people. The recognition that coal mining caused chronic obstructive lung disease, for example, long disputed by other medical researchers, came about as a result of our research although it was primarily targeted at finding appropriate preventive dust standards. Dust standards in the wool and PVC industries are also based on research I led. I am currently working on a case for recognition of solvent-induced neurological disease in the UK. Regrettably, occupational disease is far from rare in the UK and many workers are seriously disabled as a consequence. In my opinion, however, the medical case for recognition of pleural plaques as a disease is flimsy in the extreme. If their Lordships’ decision were to be overturned by legislation, the financial benefits to workers, lawyers and experts would be balanced by a return to the situation whereby it again becomes difficult to explain to well people that they are not seriously ill, with the attendant psychological consequences.

Anthony Seaton
5th October 2009 and revised 28th January 2011


1. The number of future cases in Great Britain of the malignant asbestos-related tumour, mesothelioma, has been estimated by Hodgson and colleagues (British Journal of Cancer 2005;92:587-93). This paper estimates that some 65,000 deaths from this disease will occur between 2001 and 2050. Approximately nine tenths of these deaths would be likely to occur in England and Wales, making 59,500 less the 9000 or so that will already have occurred since 2001.

3. Assuming all patients with asbestos-related mesothelioma have plaques, this allows estimation of the numbers of cases of plaques currently in England and Wales with such radiological abnormalities. Were, say, 100% of individuals with plaques to develop mesothelioma, there would now be c50,500 men with plaques currently in England and Wales, since it is reasonable to suppose that the large majority of future mesothelioma patients already have plaques as a consequence of past exposure (it is unlikely that current exposures to asbestos will cause mesothelioma). This is a minimum figure for plaques.

3. More realistic figures may be obtained by making assumptions about the risk of developing mesothelioma in individuals with plaques. Thus, if say 50% of those with plaques were to develop the tumour, the numbers currently with plaques would be 101,000 men or if (a more realistic figure) 5% were to develop mesothelioma there would be 1,010,000 men currently with plaques in England and Wales. This would represent around 4% of the adult male population. If my original assumption is wrong, and say only 50% of people with mesothelioma have plaques, the figure would be halved to around 2% of the male population.

4. To put these estimates into perspective, the estimates derived by Peto and colleagues are helpful (Lancet 1995;345:535-39) The highest risks of mesothelioma occur in the cohort of individuals born in the years 1940-58 and risks have declined in cohorts born subsequent to 1948. In those males born in that period, approximately 1% have died or are expected to die from mesothelioma. The highest risks in terms of trades are among shipyard workers, carpenters, electricians, fitters and construction workers in these 1940-1950 birth cohorts, averaging between 2 and 7% over a lifetime. The cost of a significant proportion of claims will fall on the public sector, especially councils. Even such high relative risks do not overall alter life expectancy which depends on more common causes of death. Roughly one in three of us will die of cancer and a similar proportion of cardiovascular disease, usually in old age. The risk of mesothelioma alters the odds of the sort of cancer from which an individual might die rather than altering the likely time at which the inevitable event of death will occur.

5. If the law recognises, effectively, that pleural plaques are a disease for which compensation might be obtained through the Courts, it is not unreasonable in the light of what happened after recognition of bronchitis and emphysema (real diseases) in coalminers to expect that law firms might maximise efforts to obtain clients by advertisement. Since the risks of both mesothelioma and plaques relate to asbestos exposure, the targets of such promotional activity would be those who had worked in the above-mentioned industries. It would be necessary to subject such individuals to radiographic investigation. Since plaques are often not easily diagnosed by simple chest films and may be mimicked by other conditions such as pleural fat pads, it is not difficult to see that this would often include CT scanning. Such investigation, whether positive or negative for plaques, would detect a proportion of incidental abnormalities requiring further investigation and causing attendant anxiety, quite apart from subjecting individuals to unnecessary radiation. The objective of any proposed law to allow individuals to seek compensation for anxiety would thus have the paradoxical effect of increasing the number of people with this condition, as well as adding to the costs on the NHS. Ultimately the management of litigation-induced anxiety falls on the NHS.

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