Select Committee on Science and Technology Written Evidence

Memorandum by Professors Martin J Newby and Professor Philip J Thomas, Centre for Risk Management, City University

  This evidence is submitted on an individual basis.



  1.  We believe that two main issues may limit the effectiveness of Government's response to the threat of a new infection:

    (i)  the lack of critical judgment on the part of senior civil servants and Government ministers when faced with scientific issues;

    (ii)  the consequent tendency to rely too heavily on a scientific advisory committee, which may in practice exceed its role by promoting one particular viewpoint to the exclusion of others both to ministers and in the scientific literature.

  2.  In addition, recent experience suggests that Government may be uncomfortable with the concept of finite but acceptable risk, which is integral to decision making under uncertainty; Government appears to have baulked at the challenge of communicating this concept to the public.

  3.  We believe that the events surrounding the epidemic of Bovine Spongiform Encephalopathy (BSE) in cattle and the outbreak of variant Creutzfeldt-Jakob Disease (vCJD) in humans may be seen as a case-study, illustrating many of the potential problems.


  4.  The Secretary of State for Health announced a possible connection between BSE and a new disease, subsequently known as vCJD on 20 March 1996, based on the 10 cases of the disease then known. The Secretary of State gave no indication of the likely size of the outbreak at the time, beyond saying that the chance of infection was "remote." However, it was possible even at that early stage to estimate the range of likely sizes of the human outbreak: it appeared that the number of human victims would be restricted to hundreds1, 2, 3 and such an assessment was communicated to the Spongiform Encephalopathy Advisory Committee (SEAC) in April 1996. The then Chairman, Prof. Pattison (now Sir John) declared himself against the idea of making estimates, before suggesting that the numbers might go as high as 500,0004. This set the tone for the Advisory Committee's subsequent pronouncements: the phrase "it is too soon to know" was used repeatedly by SEAC members, while at the same time the spectre was raised of a 100,000 or many hundreds of thousands of human victims5, 6, 7, 8, 9, 101. Nor was reference made to the low number of human victims that was, as far as we can tell, generally agreed to be most likely11, 12, 13. This attitude seems in part to be based on the view that a full scientific understanding of the disease was required before any decisions could be made. An estimate of the size of the outbreak was the key requirement for planning and decision making, yet the Committee has never adopted a clear position on the question.

  5.  We repeated our calculations at intervals, and found that our predictions for the characteristics of the human outbreak hardly changed over the years14, 15, 16, 17, assuming that BSE was the root cause. The period between human infection and death was estimated as below 10 years, most probably just above seven years. The most likely number of human victims has always been calculated to be about 100, and the current estimate is 130, exactly the same as the figure advanced in 1996. The upper bound for the number of human victims has always come out as a few hundred. These figures are fully consistent with the incoming low figures for vCJD deaths. Confirmed deaths from vCJD stand at 93 as of 4 October 2002, an increase of just 5 over the past year18. Including cases classed as "probable", both living and dead, brings the total to 127, up from 107.

  6.  However, guided by SEAC's advice that hundreds of thousands of fatalities were a real possibility, Government instituted draconian measures after March 1996. While the earlier countermeasures had cost tens of millions of pounds a year, the very extensive countermeasures introduced after March 1996 have cost around £1 billion pounds per year19. These measures seem to have been introduced without an analysis of either costs or benefits.

  7.  We have been able for some time to estimate the number of lives that might have been saved by this dramatically increased annual expenditure16, 17. Reviewing all the countermeasures introduced from the earliest days, we may draw up Table 1.

MeasureDate introduced Number of lives saved
Ruminant Feed Recycle (RFR) banJuly 1988 Thousands
50 per cent and 100 per cent Compensation Orders August 1988 and
February 1990
Specified Bovine Offal (SBO) banend 1989 Hundreds
Measures after March 1996, including the Over 30 Months Scheme (OTMS) April 1996 onwardsUp to about 10

  8.  By far and away the most important countermeasure was the Ruminant Feed Recycle (RFR) ban, introduced in mid-1988. This cut off the fundamental source of infection, leading to the eventual termination first of the BSE epidemic and then of the vCJD outbreak, although the long incubation periods associated with both BSE (five years) and vCJD (seven years) have meant that the process of ending the interlinked outbreaks has been protracted. Without this measure the number of human infections might have reached hundreds per year before the first cases of vCJD were diagnosed, and it is likely that thousands of human infections would have occurred before the public changed its eating habits sufficiently to avoid further infection.

  9.  The next most important countermeasures were the Compensation Orders and the SBO ban. Each of these measures had been implemented by early 1990, and each is estimated to have saved hundreds of lives. Our analysis indicated that the SBO ban had been applied with an efficiency of only about 66 per cent in the early to mid 1990s, a figure confirmed independently by direct calculation from the recorded weights of meat and offal20, 21. There is evidence that the necessary tightening up in the application of the SBO ban did not happen until 199622. More rigorous enforcement of regulation in the early to mid 1990s might have reduced the eventual human death toll by about 100.

  10.  However, the very extensive countermeasures introduced after March 1996, including the mass slaughter associated with the Over 30 Months Scheme (OTMS), were introduced only after the main danger to human health was almost past. Further measures could have only a marginal effect since only about 10 lives could have been at risk, a fact that imposes a low upper limit on their possible effectiveness.


  11.  As was clarified in the BSE Inquiry23, there were delays in identifying BSE as a new disease and in introducing adequate countermeasures against it. Nevertheless, the most important BSE countermeasure, the RFR ban, came into force in July 1988, within 19 months of the first formal identification of the disease, and all the most important measures were in place by early 1990, although the SBO ban was not enforced properly until 1996.

  12.  While the early countermeasures were the most effective in containing the outbreak of vCJD, they did not eliminate the chance of contracting vCJD completely. Nevertheless it was suggested initially that these protective measures removed any threat to humans from BSE and so guaranteed absolute safety. The realisation in early 1996 that there were likely to be human victims24 caused an abrupt switch in policy. Government felt unable to sustain the line that these same measures, subject to strengthening and limited extension, could form a continuing basis for combating the disease. Hence Government began introducing immediately a series of additional countermeasures that were two orders of magnitude more expensive than those enacted previously. Most importantly, as has been noted above, the new measures were destined to have a marginal effect simply because the success of the earlier, much cheaper measures, which had reduced the number of people at risk to a low level.

  13.  An understanding of the limited scale of the problem would surely have caused the Government to question the wisdom of authorising the very large expenditure incurred post March 1996 and to explore alternative ways of achieving similar, or the same, reduction in risk more cheaply. For example, the laxity already highlighted in the early enforcement of the SBO ban suggests that major benefit might have been drawn simply by policing existing countermeasures very much more rigorously.

  14.  Advice on the probable scale of the vCJD outbreak was made available to Government at the time1, 2. Unfortunately the Government chose to be guided by the erroneous view that there might be a vCJD epidemic with hundreds of thousands of victims. The Government's continued inability to give proper consideration to the spectrum of scientific opinion has proved to be very expensive and must be a major cause for concern. It is clear that those tasked with devising policy—ministers and senior civil servants—need to adopt a more critical attitude to the scientific advice they are offered, even when that advice comes from one of their own advisory bodies. They need also to be familiar with the concept of finite but acceptable risk, and realise that absolute safety is rarely an achievable goal in a hazardous world.


  15.  It became evident from 1996 onwards that an inflexible scientific orthodoxy was becoming established based around the views of SEAC members27. For example, our difficulties in getting our first paper published following an initial welcome from Nature have been documented15. The paper14 was eventually published in the British Food Journal, but not before the editor of that journal had felt the need to consult no less than six academic referees. This unprecedentedly large number was occasioned by the need to find additional referees independent of SEAC so as to obtain a properly impartial opinion. Acceptance of the paper in a refereed journal enabled us to submit evidence to the BSE Inquiry. Publication of our work stimulated many letters from within the scientific and medical community expressing relief at the opening of the debate on the scale of the vCJD problem. Several other authors offered evidence of the moderate size of the outbreak28, 29. All these contributions were dismissed by the Chairman of SEAC. In a similar vein, it is noteworthy since the more recent publication of Venters' paper30 in the British Medical Journal how many statements have appeared in that journal's on-line correspondence column welcoming the first open discussion on whether a link from BSE to vCJD has truly been established31.

  16.  It is now apparent that several sets of scientists previously suggesting very large figures for the potential size of the vCJD outbreak have at last reduced their top estimates by several orders of magnitude, thus converging on the low figures advocated consistently by the present authors. For example, it was only when the incubation period was assumed to be comparable with the average lifespan of a UK citizen that one team was able to reproduce its previous upper bound of more than 100,000 deaths8. More relevantly, it is striking how that team's estimate of less than 2900 human victims for an incubation period of 30 years was a hundred times lower than the figure they advanced just one year earlier7. Meanwhile groups that included the current Chairman of SEAC on the one hand, and the past Deputy Chairman on the other, have now come around to using a similar estimation approach24, 25 to that we have always advocated. Given that they are using essentially the same methodology, it would be expected that they would calculate similarly low upper bounds and, indeed, this turns out to be the case. The Chairman has now stated publicly32 that the outbreak could be expected to be at most a few hundred victims.

  17.  Valleron, Boelle, Will and Cesbron replied to our comments on their paper to the Editor of Science with the statement that "To be right too early is to be wrong". We have to disagree with this comment. We find it difficult to disregard the very large amount of money spent since March 1996 to small effect, the disruption to the beef industry and to international trade, and the unnecessary fear and suspicion raised amongst the public.


  18.  The modelling within SEAC has not been directed to supporting decision making, but rather to the exploration and confirmation of scientific theories. Anderson's group in particular has used simulation studies which have the weakness described by the former Government Chief Scientist as "speculative exploration of . . . epidemiological models whose parameters are no more than illustrative guesses"33.

  19.  There has also been a failure to apply logical arguments about the consistency of empirical data and model predictions. In 1999 an average incubation period of 30 years was given serious consideration when the mean age of onset was 26. Furthermore, since exposure to BSE could have occurred only in the 18 years since 1984, such a long average incubation period opens the possibility of another causal mechanism for vCJD. However, wider arguments about the consistency of data and causal mechanism34 have been largely dismissed by those close to SEAC34.


  20.  Our impression is that ministers and senior civil servants have been reluctant to apply their own critical judgment to the problem of BSE and vCJD in the period since March 1996. They have appeared instead to be content to rely more or less exclusively on the judgment of a Committee, SEAC, that should properly have been a source of advice only.

  21.  It is not unnatural that the research scientists making up SEAC should be enthusiasts for their own view, but we have encountered occasions where this enthusiasm has displayed itself as intolerance of differing views. Scientific debate has suffered in consequence, and the potential for diverse scientific advice for Government has been reduced. We feel that benefit would be gained by reviewing both the make-up and the operational terms of reference for such scientific advisory committees.

  22.  A feature of the later stages of the BSE/vCJD crisis has been the willingness to spend very large sums of money to avert a small number of fatalities, perhaps under the belief that this is what the public wants. The problem is that there is competition for Government money, and that money spent on BSE/vCJD is not available for other uses, whether it is building new hospitals or improving the equipment of HM Forces. Nor will it be so easily available for combating an outbreak of infection that may be much more serious.


  1.  Thomas P J (1996) "BSE/CJD: the need for statistics", letter to Lord Wade, 2 April. Copy supplied along with WS313 to the BSE Inquiry in December 1998, held there in "Bundles".

  2.  Lord Wade of Chorlton (1996), Parliamentary Debates (Hansard), House of Lords Official Report, HMSO, Vol. 571 No. 76, 17 April, pp. 695-6.

  3.  Hallberg, Oerjan (1996), "Estimating human BSE numbers", [email protected];

  4.  "It's been six months—should we stop worrying", interview with Prof. John Pattison, by Victoria Macdonald, Sunday Telegraph, 22 September 1996.

  5.  Cousens, S N, Vynnycky E, Zeidler M, Will R G, and Smith P G, (1997) "Predicting the CJD epidemic in humans", Nature, Vo,. 385 pp 197-198, 16 January 1997.

  6.  Ghani A C, Ferguson N M, Donnelly C A, Hagenaars T J and Anderson R M, (1998) "Epidemiological determinants of the pattern and magnitude of the vCJD epidemic in Great Britain", Proc. R. Soc. Lond. B265, pp 2443-2452.

  7.  Ferguson N M, Donnelly C A, Ghani A C, and Anderson R M, (1999), "Predicting the size of the epidemic of the new variant of Creutzfeldt-Jakob disease", British Food Journal, Vol. 101, No. 2, 86-98.

  8.  Ghani A C, Ferguson N M, Donnelly C A, and Anderson R M, (2000) "Predicted vCJD mortality in Great Britain", Nature, Vol. 406, 10 August 2000 pp. 583-584

  9.  Interview with Prof. Peter Smith, Chairman of SEAC, and Prof. Roy Anderson, member of SEAC (2001), The Daily Telegraph, 25 May.

  10.  Anderson R (2001) "The potential human threat", The Journal of the Foundation for Science and Technology, June, pp 13-16.

  11.  Smith P G, (1999) "Predictions about the future course of the variant CJD epidemic", BSE Inquiry, Witness Statement 583.

  12.  Thomas P J and Newby M J, (2000) "Response to WS583 from Professor P G Smith entitled `Predictions about the future course of the variant CJD epidemic' ", BSE Inquiry, Witness Statement 313B.

  13.  Thomas, Philip and Newby, Martin, (1999-b) "Reply to `Predicting the size of the epidemic of the new variant of Creutzfeldt-Jakob disease'", British Food Journal, Vol. 101, Nos. 3 & 4, 284-288.

  14.  Thomas, Philip and Newby, Martin, (1999-a) "Estimating the size of the outbreak of new-variant CJD", British Food Journal, Vol. 101, No. 1, 44-58.

  15.  Newby M J and Thomas P J, (1998) "Estimating the size of the outbreak of new-variant CJD from incoming data", BSE Inquiry, Witness Statement 313.

  16.  Newby M J and Thomas P J, (1999) "Ranking the preventative measures for new-variant CJD using data on human deaths to the end of 1998", BSE Inquiry, Witness Statement 313A.

  17.  Thomas P J, Newby M J, and Zwissler R (2002) "New predictions for vCJD numbers", paper submitted to British Food Journal, September.

  18.  Department of Health, (2002), Monthly Creutzfeldt-Jakob Disease Statistics,

  19.  National Audit Office (1998) "BSE: the cost of a crisis", Report by the Comptroller and Auditor General, 8 July 1998.

  20.  Fleetwood, Andrew (1998-a), BSE Inquiry, Witness Statement 127.

  21.  Fleetwood, Andrew (1998-b) Testimony to the BSE Inquiry, Day 55, pp 89-93.

  22.  Ministry of Agriculture, Fisheries and Food (1996) Bovine Spongiform Encephalopathy in Great Britain, a Progress Report, November, p.7 and Appendix 3.

  23.  The BSE Inquiry (2000),

  24.  Will R G et al. (1996), "A new variant of Creutzfeldt-Jakob disease in the UK", The Lancet, Vol. 347, pp 921-5

  25.  Huillard d'Aignaux J N, Cousens, S N and Smith P G (2001) "Predictability of the UK variant Creutzfeldt-Jakob disease epidemic", Sciencexpress/ / 25 October 2001 / Page 1/ 10.1126/science.1064748

  26.  Valleron, A-J, Boelle P-Y, Will R and Cesbron J-Y, (2001) "Estimation of epidemic size and incubation time based on age characteristics of vCJD in the United Kingdom", Science, Vol. 294, pp. 1726-1728, 23 November.

  27.  Newby M J (1999) "Risks, Decisions and vCJD", The Biologist, November.

  28.  Sneath P H A (2000) "Statement of P H A Sneath, Emeritus Professor of Microbiology, University of Leicester", The BSE Inquiry, Witness Statement 606, 4 February.

  29.  Southwood, Sir Richard (2000), "Supplementary statement by Sir Richard Southwood", The BSE Inquiry, Witness Statement 1E, 10 May.

  30.  Venters G A (2001) "New variant Creutzfeldt-Jakob disease: the epidemic that never was", British Medical Journal, Vol. 323, pp 851-861.

  31.  On-line correspondence (2001, 2002), British Medical Journal,

  32.  Smith P (2002) Interview on Farming Today, BBC Radio 4, 11 October.

  33.  Krebs J R, May R M, Stumpf, M P H (2002) "Theoretical models of sheep BSE reveal possibilities but we must remember that these theories are based on speculation, not on fact", Nature 415, p 115, 10 January.

  34.  Will R G (2001) "New variant Creutzfeldt-Jakob disease: the critique that never was", British Medical Journal,

October 2002

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