Less than two hours after a gagging order on him was lifted, Dr Arpad Pusztai reiterated his fears about transgenic potatoes he had used in experiments on rats. "I would not eat them," he said. His work is now being submitted for review by independent scientists, who will inform the Government whether it has any merit. Previously Dr Pusztai had claimed, through intermediaries, that the Rowett Institute in Aberdeen, where he had carried out the work, was suppressing his results.
Yesterday, the Rowett announced that it would publish the results and pass them for independent examination to the Royal Societies in London and Edinburgh.
Since being forced to retire last August, after the rat experiments were discredited by an investigation at the institute, Dr Pusztai, 68, has suffered a heart attack and been under a legal ban preventing him discussing the matter publicly.
In a statement yesterday, the Rowett said: "Dr Pusztai has been repeatedly requested to provide papers for publication on all his work. He has not yet done so." It added: "The institute can no longer be responsible for his analyses or views."
Meanwhile, leading British experts in plant science launched a withering attack on Dr Pusztai's work with rats fed GM potatoes, some of which had had lectins - a potential toxin - added separately.
The results were a "red herring", said a panel of scientists from universities and publicly funded research institutes, and should not be used as an excuse for a moratorium on the development and growth of transgenic crops. One of the panel accused Dr Pusztai of double standards, pointing out that he had applied for a biotechnology patent on a plant protein, and had claimed in other studies that the same lectins used in the Rowett experiment could benefit health.
"The gentleman wants it both sides," said Professor Christopher Leaver, head of the plant science department at Oxford University. "The experiments from what I know of them were rather muddled. We must not generalise from a simple, lab-based experiment."
Supporters of Dr Pusztaihave claimed that the results of his rat feeding experiments indicate that the "gene switch" used in the process - called a cauliflower mosaic virus promoter - may stunt the growth and immune system.
However, Professor Leaver said the cauliflower mosaic virus is ubiquitous and everyone has eaten it many times with their food. "It's the most widespread gene promoter in science and there is very little doubt it is safe," he said.
Ray Baker, chief executive of the Biotechnology and Biological Sciences Research Council, said Dr Pusztai's views were unrepresentative and that there are thousands of scientists who would support the potential benefits of GM food and crops.
He said it was important "to reject the idea that scientists are speaking with different voices" on an issue that has generated 25,000 field trials in 45 countries involving 60 different plant species. Professor Don Grierson, a geneticist at Nottingham University whose work led to the first GM tomato, said his findings had meant less waste and a better product. "It's wrong to say it's Frankenstein food," he said.
Claims that GM food is not thoroughly tested were also attacked by Mike Gasson, head of genetics and microbiology at the Institute of Food Research in Norwich. The tests on GM food cover nutritional value, potential toxicity, the unwitting transfer of genes from one organism to another and the concern over possible secondary effects of genetic modification. "All of those issues are very rigorously assessed ... and nothing in the marketplace now is in anyway unsafe," said Dr Gasson.
t A coalition of 29 consumer, development, health and environment organisations called for a five-year block on commercial growing of GM foods for commercial purposes yesterday. "The Government seems to be deaf to all but a few, carefully selected commercially based opinions," said the campaign co-ordinator, Sandra Bell.
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