Genetically Modified/Altered Foods - What Does It Mean? Is It Safe?
By Charles Arthur
Q What does it mean if a food or crop is genetically modified? A That the DNA in its cells has been altered to add genes from other organisms, such as bacteria, other plants or even animals. (The "antifreeze" genes that fish produce has been added in experiments to some plants, though none is on sale.)
Q How is it done? A Either by using a naturally occurring plant virus to "infect" the target plant with the new genes, or by literally firing the extra DNA on tiny gold beads into the cell nucleus, where the DNA resides. Neither method is precise, but once the new genes have been successfully added, the cell can be multiplied to produce a brand new plant that nature could not have. This does not, however, make it a "mutant": those are naturally occurring.
Q Is the controversy about how genetically modified foods might affect us if we eat them, or about how genetically modified crops might affect the environment while they are growing? A Both.
Q What's the difference between genetically modified, genetically engineered and transgenic? A None - they are synonyms.
Q What are the main ways in which plants are currently genetically modified? better. But for growing, they can be modified to be tolerant of large amounts of powerful weedkillers and insecticides which would otherwise kill them. That potentially means increased productivity.
Q What are the fears arising from these modifications? A For foods, that we might swallow something with genes which could behave unpredictably - for example, somehow mixing with bacteria in our stomach to produce a strange new organism. DNA has a half-life of about 10 minutes in the stomach, so some of those fears have a basis in fact. But processing, such as turning a crop into oil, destroys the DNA. For growing, the worry is that the powerful pesticides will kill everything else in and around the field, such as wildflowers and insects, and thus the bird life which depends on the seeds and grubs. The genes for pesticide resistance might also cross into wild plants, creating an "arms race" in that more, rather than fewer, pesticides have to be used to suppress weeds.
Q What sort of food is currently genetically modified? A You can buy tomato puree made from tomatoes modified to stay fresh longer. Some vegetarian cheeses are made with genetically modified bacteria, which carry out the same function as rennet, the animal protein. But many breads, biscuits, cakes and other foods may contain traces of modified soya: about 30 per cent of the soya beans grown in the US, the world's major producer, are modified to be resistant to a particular herbicide.
Q Why doesn't the Prime Minister back a moratorium on the commercial growing of GM crops, if the Government's official adviser, English Nature, does? A We do not know. At Prime Minister's Questions on Wednesday, he took the line that ministers in trouble often do, which is that they are "following the best scientific advice". The problem is that on this topic, the advisers are divided. The Advisory Committee on Releases to the Environment (Acre) thinks no moratorium is needed; English Nature does.
Q If GM crops are so safe, why do they need all these planting trials and so many regulations? A Because of scientists' worries that cross-pollination with wild plants will lead to the new genes spreading uncontrollably.
Q Will they? A Nobody knows for sure.