New Scientific Study Shows that GE Corn Kills the Soil


New findings say genetically altered corn can poison the soil
The warning suggests that pesticides can stay in the ground for months.

Robert C. Cowen
Special to The Christian Science Monitor

Researchers are raising warnings about genetically
engineered corn that makes its own pesticide, giving new perspective to
concerns about a development meant to reduce the need for
chemical pesticides.

The corn's toxin is supposed to kill only the pests it's
aimed at. But lab tests have shown that the roots exude the poison
into the soil where it can remain indefinitely.

Other recent studies have found that the pollen of such
genetically altered corn can kill monarch butterfly larvae,
and that lacewings - natural predators of insect pests - die
when fed corn borer worms raised on the plants. Critics discounted
such findings as unnatural laboratory conditions unlikely to
prevail on the farm.

The new warning published today in the journal Nature also
springs from the test-tube. But this time, the findings
identify a phenomenon that can directly affect farmers' fields. It is
"very definitely" a concern, says microbiologist Guenther Stotzky
of New York University, who reported the discovery along with
his colleague Deepak Saxena and Saul Flores of the
Venezuelan Institute of Scientific Investigations.

The corn produces the active part of an insecticide made by
the bacterium Bacillus thuringiensis. The toxin appears in the
leaves, stock, pollen, and roots. When it's ingested, caterpillars
stop eating and die.

Soil bacteria destroy the toxin if they can get at it. Dr.
Stotzky and his colleagues found that the poison binds to clay
particles and humic acids found naturally in most soils. Instead of
disappearing in about 25 days, it is active for at least 234

The scientists note that pollen falling on the ground and
corn stocks plowed back into the soil add to the toxin that roots
exude. They don't know if build-up would continue or level

Bt corn toxin is different from Bt sprays widely used as an
alternative to chemical insecticides, Stotzky explains. The
latter are crystals that only become active in the target insects'
digestive systems. That's why they don't harm other

The corn carries a gene that produces the active form of the
poison, which puts pressure on soil organisms. No one knows
the consequences, Stotzky says, but "we should stop at this
point and consider these things."

He may get his wish. The US and other countries use Bt corn
widely, but it is falling out of favor with growing consumer
resistance to foods derived from crops genetically modified
to carry alien genes (so-called GM foods). Some major food
companies insist that suppliers segregate GM crops. Non-GM
corn now fetches premium prices.