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If you're looking for a topical issue that polarises opinion, you can't go past genetic modification (GM). At one end of the spectrum, GM food is the answer to world hunger, at the other, it's a ticking time bomb set to wreak havoc on human health and the natural world.
For thousands of years, people have been altering the genetic make-up of plants and animals by crossbreeding closely related organisms with desirable characteristics. Genetic modification, which involves copying genes from one species into another, provides a way to fast track this process - and also to massively expand the possibilities. Supporters say GM can make agriculture greener by enabling farmers to use less pesticide and switch to safer herbicides, for example. Critics say GM crops pose threats to human health and the environment.
The debate is highly charged, to say the least, and environmental groups, such as Greenpeace, frequently find themselves pitted against not only the big seed companies, like Monsanto, but scientists from organisations such as the CSIRO.
As far as Australians are concerned, generally, we're not comfortable with GM foods - and our attitudes haven't changed much in the past five years, according to surveys by Swinburne University in Melbourne. People lack trust in the institutions responsible for commercialising GM crops, the researchers found.
But some scientists in favour of GM worry that what they see as unfounded scare stories are helping to drive unnecessary fear and lack of trust. Establishing what's fact and what's hype on both sides of the debate is vital - not least because the number of GM crops being planted is on the increase worldwide.
Since the first commercialisation of GM crops in 1996 there's been a steady nine million hectare increase in their production each year, according to the latest figures from the International Service for the Acquisition of Agri-biotech Applications. In 2009, 134 million hectares of GM crops were planted worldwide, with the US accounting for nearly 1/2 of that total. Soybeans are the most popular GM crop, but maize takes a big share. In Australia, just over 20 per cent of our main GM crop, canola, is now genetically modified. And that figure is set to increase - in January this year Western Australia joined New South Wales and Victoria in permitting the commercial planting of the GM variety.
By far the most popular GM trait worldwide is herbicide resistance - the ability of a plant to survive a poison that doesn't differentiate between crops and weeds. The primary benefit is that farmers can spray crops with a herbicide and kill only the weeds. And in many cases, it has allowed farmers to switch to using safer herbicide. Take, for example, canola. US seed giant Monsanto added a bacterial gene that makes the GM crop resistant to a herbicide called glyphosate (Roundup), which is much less toxic than atrazine, the one commonly used with conventional canola.
"Mounting evidence of the environmental risks of atrazine really won me over to GM canola," says Rick Roush, a pest expert and dean of the Faculty of Land and Food Resources at the University of Melbourne. The soils in which herbicide-resistant crops are grown also need less tilling, which is better for the soil. The second most common GM trait is pest-resistance. GM cotton plants, for example, have been modified to produce a bacterial toxin (commonly called 'Bt') that kills a common caterpillar pest - massively reducing the amount of insecticide needed to protect the crop.
When Roush first heard about the genetically modified Bt cotton, in the 1980s, he thought it sounded like a terrible idea. "What really changed my mind was when I went to Mississippi to look at some of the field trials of Bt and non-Bt cotton, and the results were spectacular. At that time, 49 per cent of all insecticide sprays in the world were for cotton. I saw that they were essentially growing cotton crops without spraying for the major caterpillar pest - and I thought, this could tremendously reduce pesticide use."
In Australia, a CSIRO study found that Bt cotton needed between only 11 and 40 per cent of the amount of pesticide required for conventional cotton. This "has major benefits for the environment and human health," says John Manners, deputy chief of the CSIRO Plant Industry in St Lucia, Queensland.
Other GM crops currently in development could have different environmental benefits. Researchers in the US
are working on GM varieties that need between 1/2 and 1/3 less nitrogen fertiliser than standard varieties, which could have significant environmental benefits. GM critics, however, see such promises as pipedreams in the same category as "clean coal" technologies.
Soybeans engineered to produce health-boosting omega-3 oils, which are currently extracted from fish, also have the potential to help the environment by taking the pressure off global fish stocks.
An additional benefit of some GM crops is that they produce bigger yields - though this doesn't hold across the board. As far as Roush and other scientists are concerned, the health and environmental benefits of GM are the most important to date. And some new strains of GM crops, such as those designed to grow better in drought conditions, look more promising in terms of increasing yields into the future in the developed world, including Australia. Finding effective ways to boost yields globally will be vital if we're to meet the estimated 50 per cent increase in demand for food by 2030, John Beddington, the UK's chief scientific adviser, told a food summit in London last year. GM certainly won't achieve this alone, he said.
Manners agrees: "It's but one technology that may help us to meet these challenges." But GM crops will be necessary to boost yields and help crops survive in harsher climates as the global population rises and global warming worsens, concluded a recent report from the UK's national academy of science, the Royal Society.
But if GM crops can promote the use of safer herbicides and less pesticide, reduce tillage and often increase yields, why aren't green groups behind them? Laura Kelly, team leader of the Genetic Engineering campaign at Greenpeace Australia Pacific, says there are environmental and health problems with GM.
The canola herbicide glyphosate may be less toxic than atrazine, but it isn't completely safe, according to Kelly. Arguing that it is preferable to atrazine "is a bit like saying it's preferable to have 1 broken leg than 2 broken legs," she says. Organic farming would be a better option to agriculture based around GM crops, she adds. But, failing that, there should be long-term health monitoring of farmers who use glyphosate on a regular basis.
Greenpeace, and others, are also concerned that farmers' increased reliance on glyphosate is driving the development of weeds that are resistant to the herbicide. This problem began well before GM crops were on the scene, but "GM crops are certainly exacerbating that," agrees the University of Melbourne's Roush. In the US, over-use of glyphosate means that some of the principal weeds of corn and soybeans, for example, have become resistant to the herbicide. "A lot of us are quite alarmed at the way things are going in North America right now," says Roush. "We're not convinced that Monsanto and others are taking it seriously enough."
However, reducing the risk of resistance in weeds isn't difficult in theory, he adds. It requires farmers to rotate crops, so they don't use glyphosate in the same field year after year after year.
Environmental groups also say that GM crops can harm biodiversity - the range of different species. The biggest study to date was done on farms in the UK and it found mixed results. There was more biodiversity with some GM crops, but less with others. Food chains based on seeds from weeds were hardest hit. Australia hasn't done such a study. "We want that kind of testing done here. It's likely to be different to the situation in the UK, where it's very much small farms," Kelly says.
And long-term field trials can throw up unexpected results. A 10-year field trial of the genetically modified Bt cotton in northern China, just published in the prestigious academic journal Science, found that populations of a type of bug that had previously been only a minor pest in the area have increased dramatically, adversely affecting a number of fruit crops. The bug seems to be immune the Bt toxin, and farmers have been using less of the traditional insecticides that do kill the bugs.
Most of the farmers growing GM are in the developing world. However, faith in GM crops as the silver bullet to the problem of hunger in the developing world is diminishing. A 2,500 page report from the UN World Food Programme, which included input from governments, NGOs and industries from rich and poor countries, published in 2008, concluded that GM technology is not a quick fix to feed the world's poor.
One of Greenpeace's concerns is that farmers who plant GM crops must buy new seeds every year, making them dependent on the global seed giants rather than being able to store good seed from previous years as they have in the past. Restauranteur Kylie Kwong has signed up to Greenpeace's GM Free Chefs Charter. At her Sydney restaurant she serves only organic and biodynamic food, which is GM-free by definition. One of the reasons for that is, as she told: "Having come to know many of the people who grow the food we serve at Billy Kwong, I am concerned...about the effective transferral of seed ownership from local farmers to global corporations."
A recent report by Olivier De Schutter, the UN special rapporteur on the right to food, found that an increased reliance on buying seed from big companies can put poor farmers into debt.
Greenpeace and other green groups are concerned that pollen from GM crops will cross to non-GM or organic fields. In Canada, all canola was contaminated with the GM variety within five years, Kelly points out. However, argues Roush, Canada never tried to segregate the two crops. His own studies, and those of other researchers, have shown that this isn't difficult to do. Commercial trials of GM canola in Western Australia in 2009 found that the GM and conventional varieties can be successfully segregated.
Some crops need to be planted further apart than others - for example, GM corn needs to be located about 100 m from conventional corn for successful separation. With canola, the distance is less. However, a small amount of cross-pollination between canola crops planted close-by is bound to happen, says Manners. Many canola markets set 'acceptable' limits for GM in 'non-GM' canola, which varies from 0.5. to 5 per cent.
But ultimately, concerns about mixing GM with non-GM largely come down to whether there are any health or environmental problems with the GM trait.
Greenpeace has found traces of GM canola in honey in Victoria. "We're concerned about the health of the bees - partly because we rely on bees for a lot of our food sources, because they pollinate so much - and for the health of the people who eat the honey," Kelly says.
In fact, potential health risks are one of the biggest planks in the GM critics' case. "The preliminary results from independent scientific research are quite alarming," Kelly claims. Kylie Kwong says: "I have doubts about the long-term safety of genetically modified ingredients."
Take the time to sort through the science behind some of the most often-cited GM health scare studies, though, and many of the conclusions look decidedly shaky.
Perhaps the most commonly cited 'evidence' for toxic effects from GM comes from work done by a French scientist called Gilles-Eric Séralini. In 2007, he re-analysed data gathered by Monsanto on rats fed a variety of GM corn called MON863, and reported finding toxic effects on their blood cells and kidneys. In 2009, he published a similar study looking again at MON863, and also at other corn lines, called MON810 and NK603. And again, he reported 'signs of toxicity', such as enlarged livers.
However, other data from Monsanto showed the same apparent problems with six other varieties of conventionally bred, non-GM corn. So is non-GM corn dangerous too? Or did Séralini pick up on variations between the rats that were entirely unrelated to GM? The answer, according to panels of scientists from Germany and France, the US, Canada and Food Standards Australia New Zealand (FSANZ), which have all reviewed the data, is the latter.
However, Monsanto's reluctance to hand over its data to Séralini - who had to obtain a court order to get it - was widely criticised.
In 2008, a feeding trial commissioned by the Austrian government found that mice fed on Mon810 or NK603 had fewer offspring and lower birth rates. This report triggered headlines worldwide, and led to calls for all GM foods to be banned. FSANZ, which considers submissions for new foods, and others, said at the time that there were problems with the experiments. And in April this year the paper was formally withdrawn, because of missing and contradictory data.
Concerns have also been raised about Bt crops, such as soybeans, which produce the bacterial toxin. "The plant is engineered to make an insect's gut explode when it eats it, which makes me a tad nervous," says Kelly.
Needlessly so, counters Roush. The toxin genes were chosen because receptors for them exist only in certain
insects, including the caterpillars that eat the beans. They won't affect beetles or honeybees or anything else, including us, because human physiology is vastly different - we just don't have the receptors these toxins can bind to, he says. People have been eating Bt for a long time, he adds, because it has been widely used as an insecticide spray.
What about the claims that GM foods cause allergies, and could be behind the increase in allergies in the developing world? There is just no good evidence for this at all, says David Tribe, who teaches food safety, food allergy and food biotechnology at the University of Melbourne.
Of course, that's not to say that every GM food is safe. For example, a pea modified by CSIRO to contain a brazil nut gene was found during its development to trigger an unexpected immune response in mice. So CSIRO dropped the project, well before the pea got close to people.
Clearly, GM foods cannot all be lumped together as either 'safe' or 'unsafe'. Each has to be tested. Then the data has to be evaluated, on a case-by-case basis. However, the way GM foods are tested and evaluated has come under fire by GM critics.
Recently, India put the commercial release of a GM eggplant on hold after criticisms that the country's biotechnology regulator had not had data from the company that created it (a joint venture between a local firm and Monsanto) independently analysed.
Among her main concerns about the possible health effects of GM foods, says nutritionist and GM critic Rosemary Stanton is "the fact that testing has been done by the companies marketing the products. I would like FSANZ to insist on independent tests."
Important independent work is done, points out Tribe. "About 30 per cent of all publications of GM food safety are independent of commercial interests," he says.
Clearly, there are some legitimate environmental concerns about some GM crops - such as weed resistance and damage to farmland diversity. Proponents believe these aren't unmanageable. And, they say, whether crops are altered using GM or conventional breeding techniques, many of the risks are the same. After all, weeds resistant to Roundup appeared long before GM crops.
As for health risks, there's no good evidence that any GM food on the market today has any. Greenpeace says current animal feeding trials, which often last 90 days, aren't long enough - it would like to see two-year feeding studies on animals. A 2008 scientific review published in the Journal of the Royal Society of Medicine noted that GM foods had been eaten by millions of people worldwide for 15 years, with no reports of ill effects.
Roush and Tribe, among others, think the ongoing concern that GM foods somehow might have long-term health effects is holding back the development and spread of GM crops that can have significant health and environmental benefits. "I was initially a sceptic of GM crops," says Roush. "But they have reduced the environmental footprint of agriculture in lots of areas in the world. And there are technologies that will be much more important that any of the ones we've seen so far - like efficiency in the use of nitrogen fertiliser. To be able to reduce that is going to be spectacularly important."