Genetically-Modified Corn
Leaves Deadly Toxin In Soil
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.
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.
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.
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.
They further discovered that the toxin persisted in the soil for at least 234 days.
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.
Bt toxin in the soil could help farmers to control pests or alternatively help breed a strain of toxin-resistant ones, the researchers said.
"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."
Bt corn was sown last year across six million hectares (15 million acres) of American farmland, roughly 20 percent of the national crop.
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.
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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