A proposal that Europe's top environment official made last month to ban the planting of a genetically modified corn strain across the bloc sets the stage for a bitter war within European Union, where politicians have done their best to dance around the issue.
The EU's environmental commissioner, Stavros Dimas, said he based his decision squarely on scientific studies suggesting that there remain long-term uncertainties and risks in planting the so-called Bt corn. But when the full European Commission takes up the matter in the next couple of months, commissioners will have to decide what mix of science, politics and trade to apply. And they will face the ambiguous limits of science when it is applied to public policy.
For a decade, the European Union has maintained itself as the last major largely GMO-free swath of land left in the world, largely by sidestepping these tough questions; it kept a moratorium on the planting of crops made from genetically modified organisms while making promises of further scientific studies.
But Europe has been under increasing pressure from the World Trade Organization and the United States, which argue that there is plenty of research to show such products do not harm the environment. Therefore, they insist, normal trade rules must apply.
In fact science does not provide a definitive answer to the question of safety, experts say, just as science could not know for sure whether the Year 2000 computer bug would be a problem.
Dimas, a lawyer and the minister from Greece, looked at the advice provided by the European Union's scientific advisory body - which found that the corn was "unlikely" to pose a risk - but he decided there were nevertheless too many doubts to permit the modified corn.
"Commissioner Dimas has the utmost faith in science," said Barbara Helfferich, spokeswoman for the Environment Commission. "But, there are times when diverging scientific views are on the table." She added that Dimas was acting as a "risk manager."
Within the European scientific community there are passionate divisions about how to apply the growing body of research concerning GM crops, and in particular Bt corn, which is based on the naturally occurring soil bacterium Bacillus thuringiensis, a toxin that is genetically inserted in the corn to kill pests. The vast majority of that research is conducted by, or financed by, the companies that make seeds of genetically modified organisms.
"Where everything gets polarized is the interpretation of results and how they might translate into different scenarios for the future," said Angelika Hilbeck, an ecologist at the Swiss Federal Institute of Technology in Zurich, whose skeptical scientific work on Bt corn was cited by Dimas. "Is the glass half empty or half full?" she asked.
Hilbeck says that company-funded studies do not devote adequate attention to broad ripple effects that modified plants might cause, like changes to bird species or the effect of all farmers planting a single biotechnology crop. Hilbeck said producers of modified organisms, like Syngenta and Monsanto, have rejected repeated requests to release seeds to researchers like herself to conduct independent studies of the environmental impact of the products.
In his decision, Dimas cited a dozen scientific papers in finding potential hazards in the Bt corn to butterflies and other insects.
But the European Federation of Biotechnology, an industry group, argues that the great majority of these papers show that Bt corn does not pose any environmental risk.
Many plant researchers say that Dimas actually ignored science, including that of several researchers who advised the EU that the new corn was safe.
"We are seeing 'advice-resistant' politicians pursuing their own agendas," said one researcher, who like others said he could not be quoted by name because of his advisory role.
But Karen Oberhauser, a leading specialist on Monarch butterflies at the University of Minnesota, said that debate and further study of Bt corn was appropriate, particularly for Europe. "We don't really know for sure if it's having an effect" on ecosystems in the United States, she said, and it is hard to predict future problems. About 40 percent of U.S. corn is now the Bt variety, and it has been planted for about a decade. Whether Bt corn is a problem depends totally on the ecosystem - what plants are near the corn field and what insects feed on them," Oberhauser said. "So it's really, really important to have careful studies."
While Bt crops produce a toxin that kills a winged pest and its caterpillar but is also toxic to related insects, notably Monarch butterflies, but also a number of water insects. The butterflies do not feed on corn itself, but on nearby plants, like milkweed; but since corn pollen is carried in the wind, such plants can also become coated with Bt pollen.
Oberhauser said she had been worried about the effect of Bt corn on Monarch butterflies in the United States, after her studies showed that populations of the insect dipped from 2002 until 2004. But they have rebounded in the last three years, and she has concluded that, in the U.S. corn belt, Bt corn has probably not hurt Monarch butterflies.
Still, she said there was still disagreement and broader causes for worry. U.S. Monarch butterflies may have been saved by a bit of dumb luck, she said, a fluke of local farming practices. Year by year, farmers alternate Bt corn with a genetically modified soy seed that requires the use of a weed killer. That weed killer, Monsanto's Roundup, killed off the milkweed - the monarch's favored meal - in and around corn fields, so the butterflies went elsewhere and were no longer exposed to Bt.
"It's a problem for milkweed, but it made the risk for Monarchs very small," she said.
Still, she said, other effects could emerge with time and in farming regions with other practices. For example, Bt toxin slows the maturation of butterfly caterpillars, which leaves them exposed to predators for longer periods.
Time will tell if there is a real problem. "Sure, time will give you answers on these questions - and maybe show you mistakes that you should have thought about earlier," she said.
For ecologists and entomologists, a major concern is that insects could quickly become resistant to the toxin built into the corn if all farmers in a region used that corn, just as human microbes become resistant to antibiotics that are overused. The pests that are killed by modified corn are only a sporadic problem, which could be treated by other means.
They worry, too, that Bt toxin is present in wind-borne pollen. It is extremely unusual for pollen to contain poison. Most pollens "are highly nutritious, as they are designed to attract," Hilbeck said, wondering how a toxic pollen would affect bees, for example.
Having reviewed the science, insurance companies have been unwilling to insure Bt planting because the risks of collateral damage to health or environment are too uncertain, said Duncan Currie, an international lawyer in Christchurch, New Zealand, who studies the subject.
In the United States, where almost all crops are now genetically modified, the debate is largely closed.
"I'm not saying there are no more questions to pursue, but whether it's good or bad to plant Bt corn - I think we're beyond that," said Richard Hellmich, a plant scientist with the U.S. Department of Agriculture who is based at Iowa State University, who noted that hundreds of studies had been done. Bt corn could help "feed the world," Hellmich said.
But the scientific equation may look different in Europe, with its increasing green consciousness and strong agricultural traditions.
"Science doesn't say on its own what to do," Catherine Geslain-Lanéelle, executive director of the European Food Safety Agency. She noted that while her agency had advised Dimas that Bt corn was "unlikely" to cause harm, it was still working to improve its assessment of the long-term risk to the environment.
Part of the reason that science is central to the current debate is that EU law as well as WTO rules make it much easier for a country or a region to exclude genetically modified seeds in the case of new scientific evidence showing danger. Lacking that kind of justification, a move to bar the plants would be regarded as an unfair barrier to trade, leaving the European Union open to penalties.
But the science probably will not be clear-cut enough to help the EU ministers dodge the bullet.
Simon Butler at the University of Reading in Britain is using computer models to predict the long-term effect of genetically modified crops on birds and other species. But should the ministers should reject Bt corn?
"My work is not to judge whether GM is right or wrong," he said. "It's just to get the data out there."
