(Beyond Pesticides, October 1, 2010) A new study by University of Notre Dame ecologist Jennifer Tank, PhD and colleagues reveals that streams throughout the Midwest are contaminated with transgenic materials from corn crop byproducts, even six months after harvest. The transgenic corn has been genetically engineered (GE) to produce its own insecticide, a toxin from the soil bacterium Bacillus thuringiensis (Bt). In a 2007 paper in the Proceedings of the National Academy of Science (PNAS), Dr. Tank and a group of researchers demonstrated that transgenic materials from corn (pollen, leaves, cobs) do, in fact, enter streams and can be subsequently transported to downstream water bodies. In a paper, “Occurrence of maize detritus and a transgenic insecticidal protein (Cry1Ab) within the stream network of an agricultural landscape,” published in the September 27, 2010 edition of PNAS, the researchers write about their nvestigation of the fate and persistence of the material and its associated Cry1Ab insecticidal protein, using a synoptic field survey of 217 stream sites in northwestern Indiana six months after crop harvest.
â€śWe found that corn crop byproducts were common in agricultural streams and that 86 percent of sites contained corn leaves, cobs, husks and/or stalks in the active stream channel,â€ť Dr. Tank said. â€śIn addition, using a sensitive laboratory test that specifically measures the amount of Cry1Ab protein from Bt corn, we detected Cry1Ab in corn collected from 13 percent of the stream sites. We also detected Cry1Ab dissolved in stream water samples at 23 percent of the sites, even six month after crop harvest.â€ť
Dr. Tank points out that a majority of streams in the Midwestern corn belt are located in close proximity of corn fields. â€śOur GIS analyses found that 91 percent of the more than 200,000 kilometers of streams and rivers in Indiana, Iowa and Illinois are located within 500 meters of a corn field, suggesting that corn crop byproducts and any associated insecticidal proteins may enter streams across the corn belt states.â€ť
Previous research has overlooked the potential for crop byproducts from transgenic corn to enter and be dispersed by headwater streams. â€śOur study demonstrates the persistence and dispersal of crop byproducts and associated transgenic material in streams throughout a corn belt landscape even long after crop harvest,â€ť Dr. Tank concludes. The research emphasizes that there is a tight link between streams and adjacent agricultural fields and dispersal of crop byproducts could affect natural ecosystems beyond field boundaries.
GE crops are already known to contaminate conventional non-GE and organic crops through â€śgenetic driftâ€ť and take a toll on the environment by increasing resistant insects and weeds, contaminating water and affecting pollinators and other non-target organisms. The long-term health effects of consuming GE food are still unknown. GE crops present a unique risk to organic growers. Wind-pollinated and bee-pollinated crops, such as corn and alfalfa, have higher risks of cross pollination between GE crops and unmodified varieties. Currently, no provision exists to effectively protect organic farms from contamination, although EPA has required â€śrefugesâ€ť or non-GE planted barriers around sites planted with GE crops. However, a 2009 study shows that one out of every four farmers who plants GE corn is failing to comply with at least one important insect-resistance management requirement.
Beyond Pesticides believes that whether it is the incorporation into food crops of genes from a natural bacterium (Bt) or the development of a herbicide-resistant crop, the GE approach to pest management is short sighted and dangerous. There are serious public health and pest resistance problems associated with GE crops. Beyond Pesticidesâ€™ goal is to push for labeling as a means of identifying products that contain GE ingredients, seek to educate on the public health and environmental consequences of this technology and generate support for sound ecological-based management systems.
For more information on GE crops please see Beyond Pesticides page on Genetic Engineering.