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- PARIS(AFP) - A widely-used
genetically-modified corn leaves traces of toxin in the soil that remain
deadly for pests for a long period and may have untold effects on other
insects, according to laboratory research reported in Thursday's issue
of Nature.
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- The study comes on the heels of experiments showing that
transgenic corn has a devastating effect on the North American monarch
butterfly, buttressing the claims of environmentalists who say genetic
engineering remains an untested and possibly perilous tool.
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- Researchers at New York University and the Venezuelan
Institute for Scientific Investigation examined a type of maize, called
Bt corn, that has been modified to release toxins in the foliage to kill
caterpillars and other pests.
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- They found that the roots of the corn also exuded the
toxin -- and that it remained active during 25 days of plant growth probably
because it was closely bound to soil particles and was thus protected from
biodegrading.
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- They further discovered that the toxin persisted in the
soil for at least 234 days.
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- The researchers said these early experiments gave no
pointer as to whether the toxin could have a long-lasting, harmful effect
on the soil. The banned pesticide DDT has been found to enter the food
chain partly because it lingers in the soil, breaking down only very slowly.
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- Bt toxin in the soil could help farmers to control pests
or alternatively help breed a strain of toxin-resistant ones, the researchers
said.
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- "There may be a risk that non-target insects and
organisms in high trophic (nutritional) levels could be affected by the
toxin," they added. "Further investigations will be necessary
to shed light on what might happen underground."
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- Bt corn was sown last year across six million hectares
(15 million acres) of American farmland, roughly 20 percent of the national
crop.
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- Earlier this year, American researchers found that caterpillars
of the monarch butterly were killed if they ate milkweed that had been
contaminated with pollen from transgenic corn.
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- US regulators have given the green light to several dozen
genetically modified crops, saying they are safe to eat and environmentally
friendly. Such crops contain genes from bacteria and viruses to make them
resistant to insects and weeds.
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