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Copyright 1996 The Sunday Telegraph Limited
Sunday Telegraph

March 31, 1996, Sunday


LENGTH: 587 words

HEADLINE: FOCUS - THE BEEF CRISIS: Why we won't take the risk Robert Matthews, Science Correspondent, on how the experts misread the public mood


IT WAS with some exas peration that Professor John Pattison, chairman of the Government's panel of experts on BSE, reiterated his considered scientific view on the risk of contracting CJD from eating beef. In all normal senses of the word, he declared, eating beef is safe. Yet with the intransigence of a surly bull, the British public and foreign governments remain unmoved. On the face of it, the explanation is simple: most people are simply too thick and irrational to understand the concept of risk. They gormlessly fret about the dangers of eating meat while driving along in cars responsible for 5,000 deaths a year. But some experts were last week pointing the finger of blame for the current crisis at Prof Pattison and his colleagues, and their ignorance of a complex field of research: the assessment of risk. By failing to understand how people assess risk, the panel of experts - and the politicians they advise - may have cost thousands of people their livelihoods, perhaps even their lives. Part of the blame lies in the failure of Prof Pattison and his colleagues to provide a basis for their statements. Why do they believe eating beef is safe? The answer lies in simple probability theory: the more independent factors that are involved in an event - like death through eating meat - the less likely that event becomes. In the case of beef, there are five (and possibly more) such factors: The animal must carry BSE - and most beef cattle never have. That animal must be sent to an abattoir for slaughter - which, given that farmers now get full compensation, has become a relatively rare event. Infected parts from the animal must find their way into human food - which again the Government has taken steps to prevent by banning certain offals. Those infected parts must survive food processing: tinning and roasting is likely to destroy any prion protein. Whatever infection remains must be able to affect humans. And, despite the fuss over the 10 patients with an apparently new form of CJD, the evidence for that link remains circumstantial. Indeed, experiments with genetically engineered mice currently suggests there is no link. Last week, Dr Helen Grant, a retired neurologist, added another possibility: that the 10 cases may simply be the result of a rare genetic susceptibility to CJD. What the scientists cannot do at present is put hard figures to all these probabilities, especially the final one. What is clear, however, is that "revelations" about one element - such as proscribed offal reaching the human food chain - are hardly cause for blind panic. Yet according to Professor Lawrence Phillips, an expert on risk assessment at the London School of Economics, even if the risks of meat eating could be quantified - say, one in a million - it would not make the slightest difference to public confidence. "The reason is that scientists and the public mean different things by risk," he said. "For the scientist, it is the probability of something unpleasant happening, while for the public it is something much more complex." Research into risk perception by American psychologists has shown that most people base their risk assessments on three key factors: dread, lack of knowledge, and the number of people involved. "Probabilities play no role at all, and the BSE issue scores high on all three of these factors," said Prof Phillips. "Instead of saying the public doesn't understand risk, they ought to get informed about the way the public thinks about risk."