GMOs: To grow or not to grow

It has been three decades since the first genetically engineered organisms but controversy continues.

Environmental groups issue dire warnings about genetically altered food but scientists continue to claim that it is neither harmful to the environment to grow nor to the human body to eat.

It has been three decades since the earliest genetically engineered organisms were created - the first a bacterium containing a salmonella gene - but they continue to stir debate. Scientists have succeeded in genetically modifying everything from fungi to mice, but it is genetically engineered plants that perhaps create the greatest controversy. The health impacts of eating such genetically modified organisms (GMOs) and environmental concerns about the transfer of their genes to wild plants are issues on which experts are sharply divided.

GMOs are commonly grown commercially in North America while Europe has been less welcoming. Some of the fiercest opposition has come in the UK, where last month trials of a potato engineered for resistance to nematode worms were abandoned after protesters destroyed the crop. EU rules state that foods containing material from GMOs be labelled as such, and many European countries have yet to grow the plants commercially. Similarly, such commercial growing has yet to take place in the UAE. The emirates, however, have not enforced rules on labelling and last year the environmental group Greenpeace revealed that out of 11 food products it tested in the UAE, seven contained GMOs.

Among the most common GMOs grown are plants resistant to herbicides and pests. Clare Oxborrow, a GMO campaigner at Friends of the Earth, the environmental group, said trials and commercial cultivation of such varieties raised many concerns. Herbicide-resistant plants, according to Ms Oxborrow, reduce biodiversity because their growth is tied to the use of herbicides that kill all plant life except the crop.

"That knocks out food for birds and insects and has potential impact up the food chain," she said. Similar issues apply to pest-resistant plants, which Ms Oxborrow said could harm "non-target" organisms such as butterflies and moths. If wild plants picked up genes that, for example, conferred resistance to a pesticide, then controlling them could prove difficult. Alternatively, if pest-resistance genes spread to wild plants, those plants could cause further harm to insect populations.

Apart from the environmental issues, Ms Oxborrow said GMOs were "a corporate-led technology" that multinational companies were using "to take over the world's food supply". "The seeds are patented so farmers cannot save them for the future. They have to buy the seed each year. For developing countries that's not very suitable," she said. Plants that are genetically modified have had specific genes from another organism added to them.These genes were isolated from that organism, cloned and transferred into the plant.

Bacteria may be used as vectors or sometimes young plants are bombarded with gold particles coated with a plasmid - a circular piece of DNA containing the genes of interest. What makes genetic engineering powerful is that it allows genes to be transferred between widely divergent organisms. For example, using traditional techniques, plant breeders may introduce genes from a wild grass into a variety of wheat.

In genetic engineering, because reproduction is not required for gene transfer, even animal genes can be introduced into plants. Also, it is possible to introduce a specified number of known genes, rather than the hundreds that might be transferred during traditional breeding. According to Mike May, a scientist at Broom's Barn, a plant sciences research site that is part of Rothamsted, the UK's largest agricultural research centre, many of the objections campaigners have to GM crops apply also to varieties created using traditional techniques.

"A [conventionally bred] crop may have enhanced disease resistance. The gene could get out into the wild. It's not unique to GMOs and the fact it happens isn't necessarily a bad thing anyway," he said. As an example, Mr May cites the implications of developing a form of cultivated sugar beet that contained genes which conferred resistance to a herbicide. "If the genes got into wild beets... they wouldn't get an advantage as we don't spray them [with herbicide]," Mr May said.

On the other hand, it might cause problems if the genes were for resistance to viruses. Another potential source of concern are pharmaceutical crops - plants grown to synthesise drugs. "These would need very careful checks. It depends on what the gene is," he said. "If it's a drug that can be toxic in some forms and it gets out so that it's eaten by mammals or birds, there could be issues. "If you get to the stage where there's a risk, you don't develop that crop. It's not a bad thing per se but if you don't want it, you don't allow it. There has to be good regulation and a case-by-case analysis."

In Mr May's view, GMOs are more tightly regulated than plants produced by other means, so the environmental or health effects will be identified before commercial cultivation. "If the gene is making the plant produce a toxin against insects, then these plants are assessed for toxin levels," he said. "If you look at conventional breeding, we've created a whole host of species that didn't exist, often using mutagenesis ? radiation to produce a whole range of mutants to select from. That's pretty random, but we don't worry about it."

A similar view is taken by Abdullah Ruwaida, a public health and environment consultant to the General Secretariat of UAE Municipalities. A biotechnologist himself, Mr Ruwaida believes it is wrong to condemn the GMOs out of hand. "It is good technology but it should be controlled," he said. "The harm that people are making about the products, it's not reasonable. They only stress the disadvantages that can occur."

While the two sides disagree about the potential safety hazards of GMOs, both camps agree that genetically modified plants have yet to fulfil early hopes. There is little definitive evidence that genetically modified plants produce better yields than conventionally bred equivalents. Given the current concern over food shortages, this issue has become more critical than ever. "People are seeing the food crisis as a reason why we need to look at GMOs again, but the [agricultural] companies have not produced increased yields," said Friends of the Earth's Ms Oxborrow.

"[GMOs] have had some benefits, but these are the convenient effects of growing them on a large scale." GM soya, for example, has yields that Ms Oxborrow said were five to 10 per cent less than conventional varieties, but the GM version was grown because it was herbicide-resistant and reduced growing costs. Farmers can spray the crop and not worry about the labour-intensive process of removing weeds.

"But there are no drought or salt-tolerant crops. We're being told these are around the corner. GM crops haven't delivered on their promise," she said. Mr May believes more time will lead to results. Genetic modification is in his view "another tool" that should be available to agriculture as it tries to improve yields. Drought-tolerant plants were "being worked on" and would become available eventually.

"[Genetic modification] is a big advantage when it comes to making crops that can grow in a dry area and that are more efficient in their use of nitrogen," he said. @Email:[e-mail]