Monday 20 June 2011

Assessments of BSE risk needed greater scrutiny, says professor

Cows in a field
Professor Cummings has examined the reasoning of scientists during the BSE outbreak

Professor Louise Cummings
Professor Louise Cummings, School of Arts and Humanities
The British government came under mounting pressure to make assessments of the risks to human health posed by this new disease.
Professor Louise Cummings

Scientific assessments regarding the human health risks of bovine spongiform encephalopathy (BSE) needed greater critical scrutiny to avoid the resulting catastrophic consequences, according to a professor at Nottingham Trent University.

Research carried out by Professor Louise Cummings, a linguist in the University's School of Arts and Humanities, suggests that weak scientific reasoning led to the risk posed to both humans and the economy being underestimated by successive governments.

Speaking ahead of her inaugural lecture, entitled Protecting the public's health: Scientific reasoning during the BSE epidemic, Professor Cummings commented: "In 1986, the emergence of a new brain disease in British cattle presented a unique challenge to scientists. How that challenge was addressed has been the subject of a public inquiry and numerous academic studies. However, none of these investigations has sought to examine the reasoning of scientists during this critical period in the public health of the UK.

"When BSE first emerged, early investigations indicated that the disease was one of the transmissible spongiform encephalopathies (TSEs), a group of human and animal diseases which are invariably fatal. With increasingly large numbers of cattle developing the disease, and media interest growing rapidly, the British government came under mounting pressure to make assessments of the risks to human health posed by this new disease. Their response was to establish a number of expert scientific committees to consider the potential impact of BSE on human health.

"A report submitted to government by one of these committees, the Southwood Working Party, concluded that the risk to human health was remote, a decision arrived at based on an analogy with scrapie disease in sheep. Scrapie had been endemic in the sheep population of the UK for some 250 years, without evidence of transmission to humans occurring.

"Often, at the outset of an inquiry, when evidence is lacking and not likely to be forthcoming in the short term, uncertainty and lack of knowledge threaten to stall the inquiry. However, a number of non-deductive reasoning strategies come to the fore in these circumstances. These strategies allow investigators to inch forward an inquiry on a tentative basis until such times as evidence is forthcoming.

"One such strategy is analogical reasoning. Analogical reasoning based on scrapie in sheep informed initial risk assessments about BSE. Although this strategy was rationally warranted at the outset of the BSE problem, it was soon to lose its rational standing. Yet, scientists erroneously continued to base their risk assessments on this flawed analogy.

"A further reasoning strategy, the argument from ignorance, was used so often as a basis of BSE risk assessments and public health communication that Lord Phillips and his public inquiry team labelled it the ‘mantra' of the BSE affair. This argument involved scientists and government ministers arguing that because there was no evidence that eating beef caused CJD in humans that eating beef did not cause CJD. Under certain circumstances, this form of argument is rationally warranted. However, these circumstances were not consistently present during the BSE epidemic."

By March 1996, when the Secretary of State for Health announced to Parliament that BSE was the most likely cause of several cases of variant CJD in young people, some 160,000 cattle affected by BSE had been slaughtered. A further 30,000 animals suspected of BSE, but not confirmed to have the disease, had also been slaughtered. As of 9 March 2011, 171 people have died of variant CJD. A study of archived human tissue for the Department of Health has also revealed that 1 person in 4,000 is currently incubating this disease.

Through her lecture, Professor Cummings will explore whether these adverse consequences could have been mitigated by greater scrutiny of the reasoning of scientists. The lecture will take place on Thursday 30 June at Nottingham Trent University's Clifton campus.

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Professor Louise Cummings
Louise Cummings is Professor of Linguistics in the School of Arts and Humanities at Nottingham Trent University. She conducts research in linguistic and philosophical disciplines including pragmatics, clinical linguistics, reasoning, argumentation and fallacy theory. She is the author of Pragmatics: A Multidisciplinary Perspective (Edinburgh University Press, 2005), Clinical Linguistics (Edinburgh University Press, 2008), Clinical Pragmatics (Cambridge University Press, 2009), Rethinking the BSE Crisis (Springer, 2010) and Communication Disorders (Palgrave Macmillan, 2012). She recently edited The Routledge Pragmatics Encyclopedia (Routledge, 2010) and is currently editor of the Handbook of Communication Disorders (Cambridge University Press). Professor Cummings has held Visiting Fellowships in the Department of Philosophy at Harvard University, and the Centre for Research in the Arts, Social Sciences and Humanities (CRASSH) at Cambridge University.