Monday, March 8, 1999 Published at 10:24 GMT
Parliament ponders GM potatoes
Dr Pusztai's rats suffered ill effects
By Environment Correspondent Alex Kirby
The scientist whose experiments on rats sparked the storm over genetically-modified (GM) plants is to tell a parliamentary committee why he is concerned.
It is considering how the government assesses the possible risks of GM foods, and their effect on human health and the environment.
In a television interview last August, Dr Pusztai described how he had fed rats with GM potatoes.
He said the animals used in one experiment had shown slight growth retardation, an effect on the immune system and changes in the weight of their internal organs.
Meanwhile, an audit committee set up by Professor James concluded that Dr Pusztai's data did not support his conclusions.
Many scientists believed the experiments were interesting but irrelevant, for two main reasons:
In lay terms, they argued, what Dr Pusztai had done amounted to proving that poisonous potatoes are likely to poison you.
None of that alters the fact that there are real concerns about GM crops.
Some concerns centre on their possible effects on health, some on their potential for harming wildlife and for escaping into the environment.
The Scottish Crop Research Institute has published research that found adverse effects in ladybirds when they were fed on aphids which had fed on GM potatoes.
It found the female insects' lifespans were halved and their reproduction reduced.
The experiments used potatoes similar to some of those used by Dr Pusztai, modified to include snowdrop lectin.
One of them is Paul Brantram. of BIBRA International, which specialises in toxicity testing.
Even if Dr Pusztai's data are statistically significant, he says, they establish nothing, because in every experiment but one the rats became malnourished.
"Organ weights fluctuate up and down unpredictably in such stressed animals.
"You would expect spurious statistically significant differences just due to biological variation in the response to starvation."
In one experiment, D249, Dr Pusztai fed the rats on raw potatoes. His critics say that experiment is meaningless, because all raw potatoes are toxic.
Dr Pusztai himself accepts that the subject has been blown out of all proportion by the media.
But he says: "On the basis of what we saw, we felt there was room for concern."