Bt corn is a genetically modified organism (GMO) that has been bioengineered to resist the European corn borer, a crop pest that can cause significant damage to crops. Many nations plant this type of corn, and it is in use in a variety of industries. Studies conducted on this GMO seem to suggest that it has no adverse human health effects, leading many government agencies to certify it as safe for use.
This corn takes advantage of a toxin produced by the Bacillus thuringiensis bacterium. The toxin, known as Bt, ruptures the intestines of the corn borer and related organisms when it is ingested. The pests typically die within two to three days of ingesting the toxin. As early as the 1930s, farmers were cultivating the bacterium as a method of pest control, and spraying the toxin on their crops to prevent infestation by the pest.
Topical application of this natural pesticide had some flaws, including uneven coverage and its eventual washing away. As a result, researchers started to explore the idea of inserting the genes that code for the toxin directly into the genetic code of the corn, along with a section of code known as a promoter, which would encourage the corn to produce the toxin, and a marker that could be used to track and identify modified corn.
After some trial and error, several companies had developed Bt corn, and the plant underwent inspection by government agencies to determine whether or not it was safe. Once approved, it could be planted by farmers, along with so-called “refuge” crops of non-Bt corn. The refuge crops are used to discourage Bt resistance by providing fodder for the European corn bearer that is safe to eat. The idea is that if a few insects develop resistance, they may mate with insects who ate from the refuge crop, diluting or eliminating the resistance. By contrast, a field covered in only Bt corn would promote resistance by killing off all of the insects which were vulnerable to Bt, and promoting the survival of resistant insects.
While this corn clearly has some advantages, it has not been without controversy. Some researchers have raised concerns that the corn or its pollen could impact butterfly populations, as butterfly larvae are vulnerable to the toxin. Studies have also shown that it has interbred with regular corn, creating weak amounts of the toxin in strains of corn that should not have any Bt present. Some opponents of GMOs have also argued that not enough is known about their potential impacts on human health, making them safety risks.