The Unwitting Labs of Genetic Modification ; Farms Brim with Altered Plants, Even Though Scientists Aren't Yet Sure of the Crops' Effects on the Environment

Article excerpt

In the highly charged debate over biotech crops, critics and supporters can agree on one thing: New strains are sold and planted before much is known about their ecological effects, and too little is being done to find out about them.

Genetically engineered corn, soybeans, and cotton already are staples on millions of acres of farmland in North America. Yet studies of potential risks often are conducted after a new strain of gene-spliced seeds has taken root on farms - too late for the environment or the approval process.

As a result, some researchers say, the world's fields are becoming a laboratory for the largest unplanned ecological experiment in agricultural history.

"We look at genetically modified crops, and we know what the potential hazards may be," says Alan McHughen, a plant geneticist at the University of Saskatchewan in Saskatoon. "But we want to know what the hazards really are before they go out" into the marketplace.

"The question of hazards is real, and it's not going to go away," he adds.

Two recent studies highlight potential ecological risks of genetically engineered crops.

In the current issue of the journal Science, a pair of British scientists suggest that starling populations could drop by as much as 90 percent if farmers adopt a new strain of sugar beets tailored to tolerate herbicides. Using a computer model, the scientists found that the starlings' plight depended on how widely farmers adopted the sugar beets and how much herbicide they applied to their fields - depriving the birds of the weed seeds they eat.

Ironically, the threat to the birds didn't come from the plants themselves, but from farming practices that could result from the plants' introduction.

Corn and butterflies

Also, late last month, researchers from Iowa State University in Ames published the results of experiments studying genetically modified corn and butterflies. It suggests that monarch butterflies are threatened by pollen from corn that's engineered to produce a toxin fatal to a pest called the European corn borer.

The work, which appeared in the journal Oecologia, is the latest in a series of yes-it-does, no-it-doesn't results from various scientists trying to determine whether the pollen seriously threatens the butterflies.

On a scientific level, "there is nothing terrible about any of these studies," even when results appear contradictory, says Jane Rissler, a senior scientist at the Union of Concerned Scientists. "No one study is really definitive; you need an accumulation of evidence over time."

But researchers say they face a number of hurdles in trying to build that body of knowledge.

First, the regulations governing tests can be counterproductive. Scientists must isolate test fields of key crops such as corn and canola because they produce copious amounts of pollen, which can be blown beyond the field and inadvertently mix with other plant species. Yet offsite effects are among the risks scientists want to quantify. …