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Mad Cows, Scientists and Politicians
Mad Cows, Scientists and Politicians
Murray Op-ed in Tech Central Station
July 20, 2004
A little over eight years ago, British Secretary of State for Health Stephen Dorrell announced to the House of Commons that scientists had identified a new strain of the fatal brain malady Creuzfeldt-Jacob Disease (CJD) and that they could no longer rule out a link to "Mad Cow Disease" (Bovine Spongiform Encephalopathy or BSE). The implication was clear: Scientists said that British beef was unsafe. (After the announcement, the 1990 photo-op in which former Agriculture Minister John Selwyn Gummer force-fed his daughter a hamburger looked like child abuse.) The panicked reaction decimated the British beef industry at a cost to the taxpayers of over £3 billion and may have helped bring down the Conservative government. Yet new evidence suggests that the whole disaster was merely a manifestation of the conflicting needs of science and politics.<?xml:namespace prefix = u1 /> <?xml:namespace prefix = o />
A new study published in the journal Veterinary Research uncovers a previously unrecognized epidemic of BSE in <?xml:namespace prefix = st1 />France, covering exactly the same period as the epidemic in the UK. The researchers, Virginie Supervie and Dominique Costagliola, "Estimate that 301,200 cows in France were infected by BSE between 1980 and June 2000" and that, "Furthermore, 47,300 animals at an advanced stage of the disease entered into the food chain before 1996, and 1,500 between July 1996 and June 2000."
For comparison, the total number of confirmed cases of BSE in the UK since 1986 is around 180,000. The number of CJD cases associated with the British BSE outbreak is 142. In France, there have been fewer than 10 cases of the strain of CJD linked to infected beef. (These have been blamed on British beef, even though France kept up an illegal ban on the import of British beef for three years after the end of the EU ban).
It may be that these numbers are not directly comparable. A scientist closely associated with the theory of a link between BSE and CJD estimates that a million BSE-infected animals entered the British food chain before the link was made. However, as I have noted elsewhere, most scientists involved in predicting the future course of the variant of CJD in the UK estimate that about 40 more people will die as a result of the disease.
The new research must call into question the strength of the BSE-CJD link. If a country can suffer a major outbreak and escape relatively unscathed without taking any precautionary action, then the seriousness of the threat may well have been overblown. The low estimates of the disease's future effects in Britain underscore this. It is important not to go too far in suggesting that the French research proves no link between BSE and CJD—perhaps red wine protects against the human disease—but all the evidence does need to be reviewed with an open mind.
What the research does show, however, is conflict between the needs of science and politics. In the British case, politicians from John Gummer onwards were demanding certainty. They needed to be able to tell the public that British beef was safe. This changed, with Dorrell's announcement, to the opposite certainty that BSE was such a significant risk that the country needed to slaughter a huge number of animals at a massive cost to the taxpayer.
Yet, throughout the epidemic, science was saying neither. It always accepted the possibility of a risk. Its estimation of that risk changed, and computer models built on that estimation predicted a runaway problem, but those models were always theoretical. But for the British public, politicians acting on that theory turned it into very real costs.
Scientists also bore a heavy cost: their credibility. The public, acting out of what is termed 'rational ignorance' (it only pays to be informed about matters that directly affect you), received the message that scientists one day were saying that beef was categorically safe, the next that it would kill you. When it transpired that beef was not killing millions, they returned to eating beef, but with the belief that you couldn't trust that scientists knew what they were doing.
The lessons of this for another current debate should be obvious. Politicians are looking for certainty on the subject of global warming: Will it be harmful or not? Scientists cannot answer that question with the degree of certainty needed. They have their models, but, as we saw in BSE, models can prove badly wrong. It may well be that, as with France and BSE, the world could withstand global warming without taking any precautionary measures to speak of.
Politicians demand much of science and scientists that they cannot deliver, particularly in the area of certainty. Scientists may sometimes be seduced by the glamour of politics to the extent that they say they can provide that certainty. Science and the public would be better served by scientists keeping a healthy distance from grandstanding politicians.