A new study indicates that a popular type of genetically engineered corn--called Bt corn--may damage the ecology of streams draining Bt corn fields in ways that have not been previously considered by regulators. The study, which was funded by the National Science Foundation, appears in the Oct. 8 edition of The Proceedings of the National Academy of Sciences.
This study provides the first evidence that toxins from Bt corn may travel long distances in streams and may harm stream insects that serve as food for fish. These results compound concerns about the ecological impacts of Bt corn raised by previous studies showing that corn-grown toxins harm beneficial insects living in the soil.
Licensed for use in 1996, Bt corn is engineered to produce a toxin that protects against pests, particularly the European corn borer. Bt corn now accounts for approximately 35 percent of corn acreage in the U.S., and its use is increasing.
"As part of the licensing process for genetically modified crops, the U.S. Environmental Protection Agency (EPA) was responsible for testing and identifying potential environmental consequences from the planting of Bt corn," says Jennifer Tank, who is from the University of Notre Dame and is a member of the team studying Bt corn.
To fulfill this requirement, EPA completed studies that assumed that plant parts would remain in fields without being carried away by streams draining agricultural lands, says Tank. In addition, EPA only tested the impacts of Bt corn on small lake organisms that are typically used to test the impacts of chemicals on aquatic ecosystems.
The agency did not evaluate the impacts of Bt corn on organisms that live in streams--even though Midwest agricultural lands where Bt corn is grown are heavily intersected by streams draining the landscape. But despite the limitations of its tests, EPA concluded that Bt corn "is not likely to have any measurable effects on aquatic invertebra
|Contact: Jennifer Tank|
National Science Foundation