The BSE inquiry

Editor's note: this article by Robert Curnow was adapted from an article originally published in the February 2001 issue of RSS NEWS, the monthly magazine of the Royal Statistical Society (RSS). I am grateful to Frank Duckworth, the Editor of RSS NEWS, the Royal Statistical Society and Robert Curnow for permission to slightly amend and publish this article. The issue of BSE/vCJD is a dramatic one that has attracted intense publicity and led to a collapse of public trust in scientists and the scientific method. The repercussions may well lead to changes in the way that scientific evidence is assessed, especially in the manner in which government seeks and appraises scientific advice. Clearly, there are implications for radiological protection given the controversial and contentious nature of the current debates concerning the risks to human health (or their absence) posed by exposure to low levels of ionising and non-ionising radiations. The mammoth report of the BSE inquiry chaired by Lord Phillips has been expertly summarised by Robert Curnow in this article and those involved in radiological protection should carefully consider the potential ramifications of what he has written. Robert Curnow is a professor of statistics at the University of Reading and a former president of the Royal Statistical Society. Any attempt to summarise the 16 volumes of the report of the BSE inquiry chaired by Lord Phillips is bound to be highly subjective. I have attempted to extract those findings and conclusions that will be of most interest to fellows of the Royal Statistical Society (RSS). Several statisticians and epidemiologists have contributed to research on BSE and vCJD and given evidence to the inquiry. They may well differ in their interpretation and emphasis on the different parts of the report. I hope that they will contribute through the correspondence columns of RSS NEWS. In 1998, I submitted some comments to the inquiry on behalf of the RSS when submitting evidence about the work of my own research group. I have to declare an interest since our research on the inheritance of susceptibility to BSE in cattle and the analysis of the maternal cohort study investigating transmission of the disease from cow to calf was funded by three grants from the then Ministry of Agriculture, Fisheries and Food (MAFF). I have also been a member of epidemiology and genetic subgroups of the Spongiform Encephalopathy Advisory Committee (SEAC). The whole report of the inquiry to the House of Commons can be found on the inquiry's website. Volume 1, Findings and Conclusions, is at (http://62.189.42.105/report/volume1/toc.htm.) The report contains some criticism of individuals but recognises that most were under considerable pressure of work and were facing the problems of a new type of disease. Little was known of the aetiology of the disease and the likelihood and method of transmission both within and between species. There are several references in the report to the lack of belief in government and in the Civil Service that the disease could be transmitted to humans. This led to a lack of urgency that communicated itself to those responsible for developing policy and to delays and a lack of rigour in implementing policy decisions. Examples of delay were that it took over three years to issue warnings and basic advice to people working in high risk trades; a so-called fast track professional letter took fourteen months to prepare, and advice was sent to schools about risks from dissecting bovine eyeballs two and a half years after these were identified by SEAC. The possibility of a risk to humans was not adequately communicated to the public. For example, repeated statements that `there is no evidence that BSE is transmissible to humans' were not qualified by the statement that such evidence would take many years to emerge. Reassurances that beef was safe to eat were not linked to the implementation of the precautionary measures that had been taken and, therefore, that previous consumption could result, as it later did, in transmissions to humans. The report says that the government must resist attempting to appear to have all the answers in situations of uncertainty. Sir Robert May, then chief scientific adviser to the government, in his evidence put it more starkly: `the full messy process whereby scientific understanding is arrived at with all its problems has to be spilled out into the open'. The situation changed drastically on 20 March 1996 when the government announced that BSE had probably been transmitted to humans as a new form of CJD, vCJD. It contains criticisms of inadequate liaison between government departments, particularly MAFF, the Department of Health and the Department of Trade and Industry. There are interesting comments on the role of advisory committees and independent scientists. It is claimed that the advice of independent scientific experts was sometimes sought and followed when decisions could have been reached more swiftly and satisfactorily within government. Advisory committees should not be asked to advise which policy option to adopt where the policy decision involves the balancing of considerations, which fall outside the expertise of the committee. Committees should rather be asked to set out a range of policy options, together with the implications of each. Assumptions underlying the advice should be made clear and the nature and extent of any areas of uncertainty identified. The report recognises the need for clearer and more detailed recommendations from advisory committees to officials. For example, it argues that the importance of removing every scrap of spinal cord from carcasses destined for human consumption would have been recognised if more clearly expressed by SEAC. The Southwood Report in 1989 on the implications of BSE is criticised for not making clear the assumptions on which its conclusion that `it is most unlikely that BSE would have any implications for human health' was based and for not making clearer that all reasonable practicable precautions should be taken to reduce the risk that would exist should BSE prove to be transmissible to humans. The Southwood Report was still being cited as saying that the risks were remote after the assumptions underlying the statement were known to be no longer tenable. It is recommended that government departments retain sufficient scientific expertise `in house' to ensure that the advice of advisory committees, and the reasoning behind it, can be understood and evaluated. I am not sure what is meant here by `evaluated' since the science should presumably be sound. Certainly, there needs to be `in house' expertise to act as an intermediary between the advisory committee and policy-makers so that the scientific advice can be properly related to alternative policy options. The report recommends that government should seek advice from the professional or other body best qualified to advise on suitable candidates for membership of advisory committees. The advice of an advisory committee should normally be made public by that committee. The RSS argued this general point when the `Freedom of Information' White Paper was published, but to no effect. The report criticises the impeding of the gathering of data about the extent of the spread of BSE by an embargo within the State Veterinary Service in the first half of 1987 on making information about the new disease public. The epidemiological data collected by the State Veterinary Service should have been made available earlier to others interested in the epidemiology of the disease, including those with experience in human epidemiology. The report argues that the appointment of a research director or `supremo' would have improved the co-ordination of research effort, including the identification of the best sources of expert assistance, and the identification of areas, including epidemiology, where research could profitably have been started earlier or pursued with more vigour. I made three comments to the inquiry in 1998 on behalf of the RSS. The first was about the lack of response from the Department of Health in 1996 to a letter from the then president, Adrian Smith, recommending the establishment of a UK working party to review the whole area of BSE and vCJD surveillance and epidemiology. The second was the need for politicians, civil servants and the public to be educated in the nature of scientific investigation and statistical conclusions. The third was a point also made in the RSS response to the government consultation document `Statistics: a Matter of Trust' about the need to include scientific investigations within `official statistics'. This was so that the design, analysis and presentation of the results of such investigations are protected from real or perceived political interference. In 1999, I was asked by the inquiry to amplify this last point. I stressed the importance of individual government departments, the Office of Science and Technology and what is now the Office for National Statistics being able to identify the need for external scientific advice where this is not available within the government service or its agencies. The recent rapid development in mathematical modelling and methods of data analysis underlines the need for this continuing involvement of external experts in specialist areas. We still have arguments to win about the extent of coverage of national statistics. I hope that the RSS will continue to offer a forum for discussion of all these issues and be active in giving advice, whether sought or not.