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Genetically modified maize (corn) has been engineered and is grown commercailly in the United States. Currently there are two traits that have been engineereds into corn, these are resistance to the herbicides and incorporation of a gene that codes for the Bacillus thuringiensis (Bt) toxin, protecting plants from insect pests. Hybrids with both herbicide and pest resistance have also been produced.
Herbicide resistant corn
Corn varieties resistant to imidazolinone herbicides and Roundup have been produced.
Herbicide resistant corn is grown in the United States and was approved for import into the EU in 2004.
Bt corn
Bt corn is a variant of maize, genetically altered by methods of to express the bacterial Bt toxin, which is poisonous to insect pests. In the case of corn the pest in the European Corn Borer. This was achieved by inserting a gene from the soil-dwelling microorganism Bacillus thuringiensis into the corn genome. This gene codes for a toxin that will crystallize in the digestive tract of insect larvae, leading to its starvation.
While announced as an outstanding example for green biotechnology by the industry, a study from Cornell University in New York suggested that Bt corn might be poisonous to monarch butterfly larvae. Later studies showed that the extreme conditions of the study could not really occur in nature.
In 2001 Bt176 varieties were withdrawn from the list of approved varieties by the competent US authorities.[1] (http://www.rense.com/general40/GMcropsfailing.htm)
The StarLink corn controversy
StarLink was a variety of Bt corn patented by Aventis Crop Sciences (a subdivision of Aventis, acquired by Bayer AG in 2002).
U.S. regulatory authorities permitted the commercial sale of StarLink seed, with the stipulation that crops produced must not be used for human consumption. This restriction was based on the possibility that a handful of people might develop an allergic reaction to a protein contained in the grain.
StarLink corn was subsequently found in food for people, with an episode involving taco shells being particularly well publicized. This led to a public relations disaster for Aventis and the biotechnology industry as a whole. Sales of StarLink seed were discontinued.
The southern portion of the U.S. corn belt planted the greatest amount of StarLink corn. It is this portion of the U.S. where corn borer damage creates the greatest economic loss to farmers.
There have never been any adequately controlled studies to determine whether StarLink actually poses any greater risk of allergic reaction than ordinary varieties of corn.
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