BIOTECHNOLOGY: GM potato infographic
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GM potato infographic
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BIOTECHNOLOGY

Going bananas over potatoes

October 15, 1999 - Medical journal The Lancet publishes controversial research by Dr Arpad Pusztai who found that feeding genetically engineered potatoes to rats stunted their growth and suppressed their immune system.

The British scientific establishment is up in arms over “Frankenstein” foods again, following an experiment that suggested there might be a health risk from genetically modified crops.

The work by Dr Arpad Pusztai at the Rowett Institute for Agriculture in Aberdeen found that feeding laboratory rats with genetically modified potatoes was bad for them – their growth was stunted and their immune systems suppressed.

The kind of potato he fed to rats had been engineered to produce a molecule called galanthus nivalis agglutinin (GNA). This is a natural insecticide, normally found in snowdrops, which if transfered to potatoes could make them resistant to aphids.

When Dr Pusztai talked about his findings on TV he was promptly fired from his job and his work was ridiculed.

Now he’s back. His research, published in this week’s medical journal The Lancet, is again causing a storm over the risks to humans of munching too many GM spuds.

His sacking so angered his scientific peers that they rallied round and took a second look at his data. Last February a group of them, led by Stanley Ewen, a pathologist from the University of Aberdeen, suggested that there was something more to worry about.

This was because there seemed to be more damage in rats that had been fed the GM potatoes than in a control group that was fed ordinary potatoes with GNA mixed in. And that suggested that the additional damage – thickening of the gut lining and poor development of organs such as the kidney and spleen – might be due not to the GNA, but to something in the genetic-engineering process itself.

Dr Ewen suggests that the blame may lie with a string of genetic material known as the 35S cauliflower-mosaic-virus promoter. Promoters are DNA switches that turn on genes.

Biotechnology companies use the 35S promoter to replace a gene’s natural promoter to make it easier to manipulate. It is found in many GM crops including bt-maize, which produces a natural insecticide that protects it from the attentions of the corn-borer moth, and Roundup-Ready soya beans, which are immune to a common herbicide used to kill weeds.

Unfortunately promoters can jump to the wrong place in a chromosome, and start switching on the wrong genes. This phenomenon could account for Dr Ewen’s observations. But it is by no means the only possible, or even the most likely, explanation.

Skeptics points out that potatoes are stuffed with so many different natural substances, in so many different concentrations, that experiments involving feeding raw spuds to laboratory animals are hard to interpret properly.

Also existing safeguards make it highly unlikely that jumping promoters could be causing problems in established GM crops. The effect is so well known that regulators in both America and the European Union require evidence that plants do not suffer from such instabilities. So far, the biotech industry has provided that evidence.

Sources
PUBLISHED: 15/10/1999; STORY: Graphic News
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