Genes, corn, butterfiles and choice

BT Corn

Double, double toil and trouble; Fire burn and cauldron bubble…
Eye of newt, and toe of frog,
Wool of bat, and tongue of dog….

What, you may increasingly wonder, is being added to your food? And why are you being deprived of freedom of choice?

When you buy corn at the supermarket, how are you going to know whether a pesticide has been spliced into the corn’s genes? A pesticide said to be harmless to humans, but which kills corn-boring caterpillars — and, according to new research findings, may also kill monarch butterflies?

There is no requirement that pest-proof corn be labelled. And without labelling, you’ll have no way of knowing which cob has been genetically engineered, and which hasn’t. Your choice is gone.

According to a new book, the federal government has approved 36 genetically engineered foods for sale. Some of these foods, such as corn, soy beans, and several varieties of canola (in the form of oils, margarines, tofu products, fillers, syrup, and cornstarch), are used in processed foods. As a result, say the authors, « As much as 60 per cent of processed foods are liable to contain genetically engineered products.’’

In addition, the authors say, « They’re putting fish genes in tomatoes and sugar beets, scorpion toxin in rice and tobacco.” Genetically engineered foods also include squash, potatoes, and cotton seed.

The book, entitled REAL FOOD For A Change (Random House of Canada, $21.95), is written by Rod MacRae, who coordinates Toronto’s Food Policy Council, Wayne Roberts, who teaches in the graduate program at York University’s Faculty of Environmental Studies, and Lori Stahlbrand, a former CBC radio broadcaster who teaches part time in the same program.

About a third of the corn and 85 per cent of the soy beans planted in Ontario are genetically engineered, as is about 55 per cent of the canola grown nation wide.

In the case of corn, genetic material from a naturally-occurring bacteria called Bacillus thuringiensis (Bt) has been spliced into corn genes — meaning that every cell in every kernel of an engineered cob contains Bt toxin.

The Bt bacteria lives in soil and kills leaf-eating caterpillars by invading their digestive system. A study at Cornell University in the United States (reported in Nature, 20 May 1999, page 214) has found that Monarch caterpillars are killed when pollen from Bt-corn is spread by wind to milkweed. Milkweed is the sole food of Monarch larvae.

In a news release published on the Cornell web site (, the researchers say that as the Monarch caterpillars ingest Bt toxin in the pollen, « the gut wall changes from a protective layer to an open sieve, so that pathogens usually kept within the gut and excreted, are released into the insect’s body. As a result, the caterpillar quickly sickens and dies….

« Monarchs are considered to be a flagship species for conservation. This is a warning bell,’’ they add, pointing out that, « Milkweed grows best in ‘disturbed habitats,’ like the edges of corn fields.’’ Corn sheds pollen for 8-10 days between late June and mid-August, which is when Monarch larvae feed.

Terry Daynard, executive vice-president of the Ontario Corn Producers’ Association, is calling for more research, and says Bt-corn is a valuable advance because it allows farmers to avoid using insecticides which are much more expensive and, to many people, more objectionable.

However, nothing he says detracts from the need for freedom of choice for consumers. Only labelling of foods will give them the power to decide what foods are best for their own health, and how they want to protect the environment.

Until governments require labelling, I know what I’m going to do. When I reach the checkout counter at the supermarket, I’m going to ask if the produce I’m buying is genetically engineered. The cashier won’t know, so I’ll ask to have the manager called. If enough people do this, maybe supermarket chains will force a change.

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