The medical journal The Lancet has been criticized by Britain's Royal Society for publishing a paper on genetically modified (GM) potatoes by controversial author Arpad Pusztai.

The study has been a source of continuing furore in Britain following a statement by Pusztai to the press last year — before any findings had been published that GM foods may stunt the growth of rats. This statement triggered widespread concern over the issue of GM foods. The row continued when the Royal Society reviewed Pusztai's data and concluded that the study was based on flawed design, execution and analysis (Nature 398, 98 & 399, 188; 1999).

The Lancet's editor, Richard Horton, says the journal raised the threshold for publication of this paper by sending it to six reviewers instead of three, the number normally used. This was because “Pusztai had recklessly made claims about his data a year ago and because of the issue's sensitivity”. The paper is accompanied by a commentary by researchers at Wageningen Agricultural University in The Netherlands who are critical of the study's design and conclusions.

But Horton defends the journal's decision to publish the paper, saying that it was made on scientific grounds. “A majority supported publication, but for different reasons. If we hadn't published, it wouldn't be surprising if someone accused us of censorship.”

Horton says that one of the benefits of publication is that Pusztai “has had to retract his original claim because his data, which we've published, absolutely don't show that genetically modified foods stunt the growth of rats”.

Aaron Klug, president of the Royal Society, said the society would not have published the paper because “it confirms the society's judgement that the experiments were flawed”. He said publication had given the study undeserved authenticity.

Peter Collins, the society's senior policy adviser, accuses The Lancet of taking “a very strong position on this. It is clear from an editorial previously published by The Lancet that the editor or the magazine were strongly supportive of Pusztai before they had seen his science. I don't think The Lancet can present its decision to publish Puzstai's paper now as a routine scientific decision.”