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