A study funded by the National Science Foundation suggests that Bt corn- a genetically-modified corn engineered to express a bacterial toxin which is poisonous to corn borers - may damage the ecology of streams draining Bt corn fields in ways that have not been previously considered. The study indicated that, when plant parts get carried away by streams draining agricultural lands, toxins from Bt corn may reach long distances in streams and may harm stream insects that serve as food for fish.

These issues have not been evaluated by the EPA prior to licensing the use of Bt corn, as their evaluation studies assumed that plant parts would remain in fields without being carried away by streams and the impacts of Bt corn were tested only on small lake organisms that are typically used to test the impacts of chemicals on aquatic ecosystems.

Source: NSF
Image: Genetically modified corn, commonly called Bt corn, is engineered to kill pests such as the European corn borer. However, a new study shows that Bt corn may also harm the caddisfly, which serves as food for fish and amphibians. The new study also shows that parts of Bt corn, such as leaves, cobs and pollen, can travel as far as 2000 meters away from source areas-a phenomenon that was not considered when Bt corn was licensed. Credit: Zina Deretsky, National Science Foundation