Perilous Times and Frankenfood
GM - Genetically modified corn 'has polluted rivers across the United
States'
By Steve Connor, Science Editor
Tuesday, 28 September 2010
An insecticide used in genetically modified (GM) crops grown
extensively in the United States and other parts of the world has
leached into the water of the surrounding environment.
The insecticide is the product of a bacterial gene inserted into GM
maize and other cereal crops to protect them against insects such as
the European corn borer beetle. Scientists have detected the
insecticide in a significant number of streams draining the great corn
belt of the American mid-West.
The researchers detected the bacterial protein in the plant detritus
that was washed off the corn fields into streams up to 500 metres away.
They are not yet able to determine how significant this is in terms of
the risk to either human health or the wider environment.
"Our research adds to the growing body of evidence that corn crop
byproducts can be dispersed throughout a stream network, and that the
compounds associated with genetically modified crops, such as
insecticidal proteins, can enter nearby water bodies," said Emma
Rosi-Marshall of the Cary Institute of Ecosystem Studies in Millbrook,
New York.
GM crops are widely cultivated except in Britain and other parts of
Europe. In 2009, more than 85 per cent of American corn crops were
genetically modified to either repel pests or to be tolerant to
herbicides used to kill weeds in a cultivated field.
The GM maize, or corn as it is called in the US, has a gene from the
bacterium Bacillus thuriengensis (Bt) inserted into it to repel the
corn borer beetle. The Bt gene produces a protein called Cry1Ab which
has insectidical properties.
The study, published in the journal Proceedings of the National Academy
of Science, analysed 217 streams in Indiana. The scientists found 86
per cent of the sites contained corn leaves, husks, stalks or cereal
cobs in their channels and 13 per cent contained detectable levels of
the insectidical Cry1Ab proteins.
"The tight linkage between corn fields and streams warrants further
research into how corn byproducts, including Cry1Ab insecticidal
proteins, potentially impact non-target ecosystems, such as streams and
wetlands," Dr Rosi-Marshall said.
All of the stream sites with detectable insecticidal proteins were
located within 500 metres of a corn field. The ramifications are vast
just in Iowa, Illinois, and Indiana, where about 90 per cent of the
streams and rivers – some 159,000 miles of waterways – are also located
within 500 metres of corn fields.
After corn crops are harvested, a common agricultural practice is to
leave discarded plant material on the fields. This "no-till" form of
agriculture minimises soil erosion, but it then also sets the stage for
corn byproducts to enter nearby stream channels.