October 12, 2010
Pesticides produced by genetically modified (GM) corn have been found dissolved in streams in Indiana, raising new questions about whether GM foods could have impacts beyond immediate food safety, a new study reports.
Jennifer Tank of Indiana's University of Notre Dame and colleagues sampled 217 streams in a 400-square-mile (1,053-square-kilometer) area in northwestern Indiana, six months after the corn harvest. Of those streams, 28 had corn "detritus" (that would be husks, cobs, leaves, and so on for those playing along at home) containing the Cry1Ab protein, which is produced by so-called GM "Bt corn" to ward off the European corn borer, an invasive pest.
The researchers, whose work was published last month in the Proceedings of the National Academy of Sciences, also found Cry1Ab protein in the water of another 50 of the 217 test stream sites, even though there were no corn husks in the water. However, all 50 of those streams were located within 1,640 feet (500 meters)--or roughly five football fields--from a cornfield.
"In this part of Indiana, there's corn and soybean throughout the landscape," study co-author Emma Rosi-Marshall, of Loyola University Chicago, told Green Guide. "It's hard to get too far before you come across another cornfield."
But the fact that the protein was found without the immediate presence of corn implies that the stuff sticks around for a goodly while, and that streams are able to transport the insecticide far and wide.
"It wasn't surprising to us, given our previous research showing that the flow in the stream dictates how far corn material transfers, that this stuff would move once it got in," Rosi-Marshall said.
Tank and Rosi-Marshall also collaborated on a paper in the journal Ecological Applications showing that the toxins in Bt corn can affect caddisflies' growth, at least in a lab setting.
The corn borer pest has the potential to develop a resistance to Bt corn and has done so in a lab, scientists have found.
As for the pesticide's toxicity to humans, nobody really knows. Indiana's streams ultimately drain into the Great Lakes or the Mississippi, but whether Cry1Ab is still present by the time the water enters the human supply is unknown.
Researchers in France found that Cry1Ab causes organ damage in rats, even when the corn made up a third or less of the rats' diets. Study author Gilles-Eric Séralini of the University of Caen and CRIIGEN, the Committee for Research & Independent Information on Genetic Engineering, said it was an open question whether the insecticide would do the same in humans.
"Unfortunately, the modified Bt toxins, mutated and as produced by GM plants, have never been tested on human cells in regulatory tests, despite our requests," he said. "This is a shame."
(Related: "Food: How Altered?")