EVEN if Arpad Pusztai鈥檚 research says little about the safety of genetically
modified foods, the controversy surrounding it serves as a reminder that even
such familiar plants as potatoes have the potential to produce fairly noxious
chemicals.
Many plants defend themselves against being eaten by producing poisons. After
generations of breeding, the plants we eat have become less toxic. But rare
genetic accidents can result in long-quiet genes producing large amounts of
toxins. This could be triggered by genetic engineering or by growing plants in
tissue culture.
More worryingly, however, it can also happen during the wholesale genetic
shuffling involved in creating new plant varieties by conventional breeding.
鈥淭here is a shunting around of genes which could potentially create a hazard,鈥�
says Roger Turner, chief executive of the British Society of Plant Breeders.
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Indeed, this has happened at least twice. A potato variety called Lenape was
withdrawn from the US market in the 1960s when it was found to contain
dangerously high levels of potato toxins called solanidine glycosides. And in
the mid-1980s, American growers abandoned a variety of celery because it
contained high levels of psoralens, which become irritants when activated by
sunlight. Workers picking the celery developed skin rashes.
New varieties of GM crops have to be shown to be biochemically similar to
their unmodified counterparts. But conventionally bred varieties require no such
scrutiny. In Britain alone, around a thousand new varieties鈥攎ore than half
of which are intended for human consumption鈥攁re tested each year
(see Table).
This involves trials to ensure that they breed true and give reliable
yields, but doesn鈥檛 routinely include a biochemical safety analysis. The story
is similar throughout the world.
So should regulators demand such tests? If consumers insist that safety is
paramount, this would be the best way to provide it. 鈥淲hen you introduce new
foods, you can鈥檛 assume they will be without hazard,鈥� says Tom Sanders, a
nutritionist at King鈥檚 College London.
But other experts argue that the huge amount of work involved couldn鈥檛 be
justified. 鈥淥f the thousands of varieties and billions of people who consume
them, there鈥檚 only a few examples of things that haven鈥檛 been beneficial,鈥� says
Don Grierson, a plant biotechnologist at the University of Nottingham. After
all, Grierson points out, for centuries people have eaten plants laden with
natural poisons. Cassava and kidney beans can both kill if they aren鈥檛 properly
prepared, he notes.