Already the problems of containing the new genetically altered varieties are evident. Pollen from genetically modified plants is spread by the wind and has been found to have pollinated plants in fields where GMOs were not planted. Although the planting of genetically modified corn is prohibited in Mexico, it has been found in several parts of the country because small farmers experimentally planted corn that had been imported from the U.S. for food and animal feed. To the North, organic canola farmers in Canada complain that it is no longer possible to grow canola that can be certified as organic because of GMO contamination.
The effect of Genetically Modified foods on biodiversity is an area of controversy. As scientists perfect genetically modified varieties and these varieties are used more and more, the natural genetic diversity of the organisms is likely to be lost. Genetic diversity is a form of "insurance" against unforeseen natural disasters (Anderson, Kym, Damania, and Jackson 302). If a species becomes subject to disease, blight, or some other environmental challenge, species with no genetic diversity will be subject to catastrophic loss, but those with genetic diversity may have individuals with the genetic make-up to resist the challenge. So important is the insurance value of genetic diversity that seed banks have been created to house genetically diverse varieties of agricultural seeds.