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A Scottish research institute this week lifted a ban on one of its scientists from speaking to the press, in a bid to dampen allegations that it had tried to suppress data indicating potential health risks in genetically modified food.

At odds: James (left) says that Pusztai was only prevented from discussing his unpublished data. Credit: PA

Arpad Pusztai, a senior researcher at the Rowett Research Institute in Aberdeen and an authority on lectins, had been banned from speaking to the press after allegedly disclosing unpublished data from his experiments on television last August.

Pusztai concluded from his data that when rats were fed with potatoes genetically modified to produce a lectin with known insecticidal properties they suffered retarded growth, depressed immune systems and reduced body weight. He was suspended for 12 days during an internal investigation, which exonerated him of any wrongdoing. But his contract was not renewed, and he retired at the end of last year at the age of 68.

Shortly after the row broke out, the institute arranged for an audit of Pusztai's results, which concluded that his data were “too inconsistent” to support his conclusions. But last week, amid mounting media interest and public alarm, more than 20 scientists from 13 countries said in a statement organized by Pusztai's supporters that they had reviewed his work and supported his conclusions.

The scientists accused the institute's director, Philip James, of gagging Pusztai and suppressing the flow of scientific information. They criticized James for refusing to make public an unpublished report by Pusztai justifying his conclusions.

James, the author of the British government's proposals for an independent food standards agency, denies the scientists' allegations that he tried to suppress commercially and politically sensitive scientific results (see Nature 394, 714; 1998). He says Pusztai was simply banned from disclosing further unpublished work to the media.

James says the ban is being lifted to counter the view “that Pusztai is subject to some kind of gagging order”. James adds that he is planning to ask an independent learned society, such as the Royal Society of Edinburgh, to convene an open, two-day meeting to discuss the issues raised by the affair.

He says he has “reluctantly” made public Pusztai's unpublished report, adding that he would have preferred what has become known as the “alternative report” to have been published first in a peer-reviewed journal. “It is simply not true to say Arpad is gagged,” says James. “I offered him a press conference [to publicize his research]. But on condition that he should get it published in a journal first.”

Pusztai's supporters claim that the institute's audit report is selective in the data it interprets. “I have the impression that it was hastily compiled and systematically biased towards brushing aside [Pusztai's] experimental findings,” says Vyvyan Howard, head of research in fetal and infant toxico-pathology at the University of Liverpool.

Similarly, Stanley Ewen, professor of histopathology at the University of Aberdeen medical school, and a former collaborator with Pusztai, accuses the audit committee of deliberately withholding critical data on the weights of rat organs.

Ewen has been reported as claiming to have confirmed Pusztai's findings from a histological analysis of tissue from Pusztai's rats. Ewen says he is trying to publish this research, so far without success.

But Andrew Chesson, head of the Rowett's nutritional chemistry unit, who chaired the audit committee, says it took account of all the data then available. The panel included an immunologist, and a plant biotechnologist from outside the institute.

Chesson says that, in many cases, the error bars on the data were almost as large as the numerical quantities. “There is simply no way that Pusztai could support his conclusions with these data.”

Earlier this week, Pusztai was continuing to refuse to speak publicly. But Luke Anderson, an environmental activist and Pusztai supporter, says the researcher is angry and hurt at how a career in which he produced 280 research papers and wrote three books has been brought to an abrupt end.

Anderson adds that one journal was offered the data, but declined to publish it. He acknowledges that few of the signatories of last week's statement are molecular biologists or immunologists. But he argues that they are all sufficiently qualified in medicine and biology to provide an informed opinion on Pusztai's data. Pusztai's results are expected to be made public this week on http://www.rri.sari.ac.uk