EUROPE is set to move the debate on genetically modified crops to a more constructive and sophisticated level. Gone will be the “Frankenstein food” epithets and wild claims that such crops can end world hunger. In their place will come a measured, less acrimonious debate based on a clear understanding of what science can and cannot tell us about GM plants (see “Answering the Frankenfears”).
That is the hope of politicians, scientists and biotech companies following the publication this week of a long-awaited report from the UK government that sets out to address public concerns over the safety of GM crops and the food produced from them. While the report does not reach any firm conclusions, its message is that neither blanket advocacy of GM technology, nor opposition to it, is sustainable. Instead, individual GM technologies should be evaluated on their merits, based on research into the costs and benefits of each one. The report also implicitly sets out the scientific uncertainties that Britain, the rest of Europe and the US must resolve if they are ever to reach a consensus over GM safety.
“I think we have broken the ice. I’m confident this is the first report in the world that has comprehensively used the science available to address concerns raised in the public domain,” says David King, the British government’s chief scientist and chairman of the 24-person panel that produced the report.
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The panel, which includes both advocates and opponents of GM technology, reviewed over 600 scientific publications. Its report concludes that the current generation of GM crops have not inflicted any significant damage on the environment, and there is no evidence they are dangerous to eat.
It also identifies serious gaps in our understanding of GM crops. Future generations of GM crops could bring new and unpredictable consequences, it warns, so our knowledge of potential hazards has to keep pace with the technology used to create such plants. In particular, the report highlights three major areas of concern: whether GM foods will spark allergies, the effect of GM crops on soil ecology and farmland biodiversity, and the consequences of transgenes spreading through the environment.
The British government is inviting comments on the report from organisations and individuals before producing a revised version in October. By then, King hopes, the panel will be able to include the results of Britain’s “farm-scale evaluations”, the world’s largest trial designed to find out whether farmland wildlife suffers when GM crops resistant to weedkillers are grown.
People on both sides of the GM debate are already saying that this week’s report will subtly change the way the issue is discussed in Britain and the rest of Europe. In place of the polarised debate, dominated by the entrenched positions for and against GM crops that have characterised the argument till now, they expect to see more constructive dialogue about how best to proceed.
This will leave the British government with some difficult choices. It had expected to come to a decision within months from now about whether to allow the commercial planting of GM crops. Such a decision would have helped other European nations facing the same dilemma. Accepting GM crops would allow Europe to trade freely with the US, where GM crops are becoming ubiquitous. Rejection could trigger a trade war. But a blanket decision on modified crops now looks less likely. Last week, the British government’s Strategy Unit published a report exploring the economic costs and benefits of GM crops (Â鶹´«Ă˝, 19 July, p 3).
“There is no scientific case for ruling out GM per se, but nor do we give blanket approval,” says King. “We consider applications on a case-by-case basis,” he adds. That approach has been widely applauded by the biotech industry and scientists, including the Royal Society. Panel member Alan Gray, director of the UK’s National Environment Research Council Centre for Ecology and Hydrology, says GM crops should be viewed in the same way we consider other technologies whose safety people are concerned about. “The metaphor I would use is vaccinations,” he says. “Are you pro or anti vaccinations? It depends on the case.”
The report says, for example, that certain modified crops are likely to be less dangerous than others. Those modified to resist weedkillers are unlikely to pose problems, even if genes from the plants spread into wild relatives. Plants such as wild sea beet that usually grow in woodland or salt marshes will gain little from being resistant to weedkillers they will rarely encounter. But later generations of GM crops could help turn wild relatives into superweeds if they pass on a trait making them resistant to certain viruses or fungi, as these wild relatives could gain an advantage over their neighbours (see ).
The report also clearly states that there is no evidence that it is harmful to eat current GM crops. Some 250 million people, mainly in the US, have eaten GM food for 7 years without any sign of ill effects. “To rule out that experience would be foolhardy,” says King.
Fears that novel genes introduced into GM foods could pass into bacteria in people’s guts are acknowledged by the report. Panel member Mike Gasson of the Institute of Food Research in Norwich says that genes from GM soya have been found within samples of gut contents removed from volunteers. But there is no evidence it is taken up by bacteria, although the possibility does warrant further investigation.
The report also dismisses calls for prolonged epidemiological studies to check for long-term adverse effects of eating GM foods. “It is almost impossible,” says King. “The human diet is very varied, and any GM food would be consumed in very small amounts, so any effects would be subtle and difficult to measure.”
Some opponents of GM technology, such as the UK-based pressure group GeneWatch, have called for such studies. But other critics concede that they would be impractical and extremely expensive. “Without a specific hypothesis to test, it would be very difficult,” says Douglas Parr, chief scientist for Greenpeace UK.
Parr, who was not a member of the panel that produced the report, says Greenpeace remains opposed to the commercial planting of GM crops in the UK, particularly because we know so little about how introduced genes may pass through the environment. But he welcomes the highlighting of areas of further research. “The fact that they now acknowledge there are real uncertainties is welcome,” says Parr. “It’s not a green light for GM crops.”
Identifying the gaps could stimulate research rather than restrict it, Parr adds. “The fact that uncertainty drives good science is inherent to the precautionary principle. Whatever you think about the field-scale evaluations, there is no doubt they will produce interesting ecological data which will still have value, whatever your position on GM crops.”
King, too, acknowledges that public concern about GM crops in Europe has helped drive research into our understanding of GM technology.
Answering the Frankenfears
IS EATING GM CROPS DANGEROUS?
What we know:
• GM food on the market is “unlikely to be toxic”. It is probably as nutritious, and carcinogenic, as conventional food. The same applies to produce from animals fed GM crops.
• Modified DNA from GM food is unlikely to transfer to bacteria in our guts. Scientists agree this would be extremely rare, as there is no definitive proof that such horizontal gene transfer has yet taken place.
What we don’t know:
• Whether there are any subtle, long-term effects of eating GM food. It is practically impossible to conduct long-term clinical trials of any food. Requiring people to eat a particular foodstuff for decades on end would compromise their diet and might seriously affect their health.
• Whether GM food spurs allergies in some people, either immediately or after several years of exposure. There are gaps in our fundamental understanding of which proteins in ordinary crops trigger allergies, and how they do it, that we need to address before tackling GM issues.
WILL GM CROPS AFFECT THE ENVIRONMENT?
What we know:
• Herbicide-resistant crops are no more invasive or persistent than their traditional counterparts. However, introducing traits such as genes that help plants thrive under the stress of drought could change that.
• Some GM crops are toxic to animals other than the pests they are designed to resist. This toxicity can work its way up the food chain to carnivores. No one knows how big this effect is in the wild, and there are no internationally accepted guidelines for studying it.
• Insects will evolve to overcome pest-resistance genes. But they also evolve to overcome conventional pesticide sprays. No one knows which will happen more quickly.
What we don’t know:
• Whether GM crops affect biodiversity on farms. Farm-scale trials are under way in Britain now, with the results expected in a few months. Even larger studies may be needed to confirm the effect on creatures that have a wide range, especially birds.
The effect of GM crops on soil ecology. The normal variation in the type and number of bacteria is so great that it is impossible at the moment to meaningfully compare GM fields with non-GM fields.
CAN GENES FROM GM CROPS FLOW INTO OTHER PLANTS, MICROBES OR VIRUSES?
What we know:
• Genes do flow between related plants, so they could move from a GM corn to a traditional one, for example, or to weeds. Most scientists think that fields can be sown so that only 1 per cent of plants of a given variety will be contaminated by novel genes in this way.
• Separating crops does not eliminate the chance of occasional cross-pollination. Genes can flow across kilometre-wide buffer zones between crop varieties.
• It is theoretically possible for plant DNA to linger in soil for months and be taken up by microbes, but no one has seen it happen. Likewise there is no evidence that virus-derived genes in GM crops would recombine with genes in an infecting virus. But it cannot be ruled out.
What we don’t know:
• Whether gene transfer will produce superweeds and superbugs that devastate the environment. This depends so much on individual genes that case-by-case studies will have to be done.
- Additional reporting by Nicola Jones