We have been told that genetically engineered (GE) material just disperses in nature, but in fact, it is remarkably permanent. Biologically engineered genes and DNA have been found to persist in soil organisms, in insects, pollen, and especially water, and have been found in agricultural ditches as much as a kilometer from the original site. The antibiotic-resistant marker genes used in the process have survived digestion by cattle and even bees, and therefore post a threat of increased antibiotic resistance up and down the food chain. This is one reason why the technology is under a de facto ban in Europe. The genes themselves are not confined to the original, patented plant, but can be spread by wind or pollen to other varieties of the same crop, and even to wild relatives.
Canada is already having tremendous problems with genetically engineered canola, which has not only spread its herbicide-resistant trait to other canola, but is now affecting its many wild relatives, creating what are being termed "super weeds." The situation is so serious that one reason the Canadian Wheat Board is actively fighting the introduction of herbicide-resistant GE wheat, apart from market considerations, is that the species has many wild relatives that could forever become contaminated with herbicide resistance."
—David Suzuki and Holly Dressel, Good News for a Change: How Everyday People are Helping the Planet (2003, Greystone Books)