The Basics on Genetically Modified Foods

Most people in the world had never given much thought to genetically modified foods until 1999, when scientist Arpad Pusztai caused an outcry by claiming to show that young rats fed GM potatoes were suffering ill health. Pusztai's headline-grabbing experiments are now widely accepted to have been "irrevocably flawed", as New Scientist put it, though some greens claim that he was the target of a shameless smear campaign and that his work still stands. Whatever the truth, the ensuing health scare about "frankenfoods" provided a springboard into the media and public consciousness for other related issues, such as GM food's ethical, environ­mental and economic implications.

By the time the government staged a public debate on the subject in 2003, the overwhelming majority of people were dead against biotechnol­ogy for food, and the big supermarkets had stopped selling most GM products. Despite this, the first licence for the commercial cultivation of a GM crop was given out just a few months later. In the event, the licensee - Bayer CropScience - decided to abandon the country as a potential market, which means that no GM crops are likely to be commercially grown there for some years to come. But modified ingredients and animal feed continue to be imported to, and sold in, and the arguments have broadened from questions over the safety and ethics of "tampering with nature" to claims that, by shunning GM crops, Western shoppers are inadvertently harming both the environment and people in the developing world.

Genetic modification is a kind of biotechnology in which the DNA of an organism, most commonly a crop, is altered. This can be done either by changing an existing part of the DNA or by adding a new gene from elsewhere - usually from a bacteria, a virus or another plant - allowing scientists to "cross" two organisms that couldn't combine in nature. GM has been a theoretical possibility ever since the discovery of DNA in 1953, but it was in the early 1980s that the techniques were actually developed, and in the 1990s that GM foods became a commercial reality.

Though the potential applications are very wide-ranging, there are only a handful of commercially available GM food crops at the time of writing, including soya, maize, cotton and canola. These modified plants are engi­neered to be either herbicide tolerant, insect resistant or both. Herbicide tolerant crops are capable of dealing with special weed killers that would kill normal crops. This, in theory at least, makes farming easier, as it ena­bles simpler and more effective control of weeds. Insect resistant crops, by contrast, have been modified to produce a naturally occurring insecticide known as Bt toxin. This approach seeks to reduce the amount of money and time spent on buying and applying pesticides.

A public outcry has temporarily halted GM planting in Europe, but there's been no such hold-up in much of the rest of the world. At the time of writing there are around six million farmers growing GM crops on roughly 125 million hectares (approximately five times the land space of the UK). The vast majority of these are in the Americas, in particular the US, Argentina, Brazil and Canada.