The independent scientists vigorously defended the work of Arpad Pusztai, an expert on plant toxins, who was forced to retire last year from his post at the Rowett Research Institute in Aberdeen after prematurely releasing the results of his experiments to the World in Action television programme .
Twenty researchers from around the world have signed a memorandum condemning the way Dr Pusztai was treated by the Rowett Institute, which said the 68-year-old scientist had become "muddled" over an experiment that did not in fact involve genetically modified potatoes.
Dr Pusztai was suspended and his annual contract not renewed. He has since been told not to talk publicly about his work on GM potatoes by his former employer.
But yesterday Vyvyan Howard, a toxicologist from Liverpool University, released data from further experiments carried out by Dr Pusztai which, said Dr Howard, supports the principal conclusion that genetically modified food can be harmful to health.
Dr Howard said that "transgenic" potatoes, which had an added gene responsible for a plant toxin called a lectin, produced damaging effects on the immune systems and internal organs of the laboratory animals. "There is obviously something going on with this transgenic potato which is not just due to the lectins. We don't have an answer to that. It needs further research," he said.
Stanley Ewen, of the department of pathology at Aberdeen University, released preliminary results of his own experiments, which showed that animals fed on GM potatoes experienced the take-up of lectin proteins into the cells of their intestines. "It may be that in GM food a drug- delivery system has been created, delivering something you didn't want to," Dr Ewen said.
Another supporter of Dr Pusztai, Professor Brian Goodwin, of Schumacher College in Dartington, Devon, said the latest results will strengthen support for an immediate moratorium on the growth of GM crops, a ban on patenting genes and an independent inquiry into the use of genetic engineering by the food and agricultural industries.
Ronald Finn, past president of the British Society of Allergy and Environmental Medicine, said Dr Pusztai's research raised serious concerns. "Dr Pusztai's results to date at the very least raise the suspicion that genetically modified potatoes may damage the immune system." If that happened, he said, the consequences of something like a flu epidemiccould be extremely serious. "You can imagine a doomsday scenario. If the immune system of the population was weakened, then the mortality would be increased many, many times."
Other scientists criticised Dr Pusztai's supporters for taking his research out of context. Professor Ray Baker, chief executive of the Biotechnology and Biological Research Council, said the potato experiments did not cast doubt on the safety of all GM food. "These potatoes were part of an experiment and were never intended for commercial production, nor are they available on the market," he said.
As the row over Dr Pusztai erupted, Tony Blair yesterday rejected calls for a moratorium on GM food and played down mounting concern. "There is no GM food that can be sold in this country without going through a very long regulatory process," he said on BBC radio. "Let's proceed on the basis of genuine scientific analysis and inquiry, proceed with very great care and caution and not get the facts mixed up."
Philip James, director of the Rowett Institute, vigorously defended his decision to suspend Dr Pusztai on the grounds that the lectin expert had become confused over key experiments on GM potatoes.
Dr James said that Dr Pusztai had claimed in media interviews to have found ill-effects on rats fed with GM potatoes with a lectin called GNA - a protein derived from the snowdrop plant - but in fact he had mistaken these results for those on ordinary potatoes that had been deliberately laced with high concentrations of another, highly toxic lectin called Con A, which would never be used in human food.
Dr James strongly denied that he had come under any political pressure to dismiss Dr Pusztai.
The environmental pressure group Friends of the Earth called on the Prime Minister yesterday to hold an inquiry into the affair.Reuse content