Despite controversy regarding genetically modified crops, some experts say a certain type of genetically modified corn may be healthy.

Gary Munkvold, associate professor of plant pathology, said Bacillus thuringiensis (Bt) corn has an advantage over conventional varieties in preventing disease caused by dangerous chemical contamination.

When insects such as the corn borer injure the plant, a fungus called Fusarium often thrives in these damaged areas, he said.

Once the plant is infected, the fungus produces a group of toxins called fumonisins that may be potentially fatal to humans and livestock.

Some populations in Africa and China are at higher risk for disease caused by these naturally occurring poisons, Munkvold said.

“Eating corn with a lot of fumonisins is associated with higher levels of esophageal cancer,” he said.

Livestock such as horses may suffer from a degenerative brain disorder called leukoencephalo malacia, while pigs may be subjected to an equally fatal lung condition called pulmonary edema, Munkvold said. Fumonisins also have caused liver and kidney failure in laboratory animals.

Richard Hellmich, United States Department of Agriculture collaborator, said the problem with using chemical insecticides or organic controls, such as the fungus Beauveria bassiana, is that they are not expressed throughout the entire life of the plant.

“With Bt corn, [the crop] gets complete protection throughout the entire season,” he said. “With other methods, you must have perfect timing. The corn borer spends the first part of the season outside the plant, then burrows inside. Once inside, insecticides don’t work.”

The use of insecticides is often impractical because it usually requires the use of aerial application, said Galen Dively, a University of Maryland pest management specialist.

Dively said the use of the fungus Beauveria as pest control is ineffective because the environment plays such a critical role.

“In the summer it doesn’t work,” he said. “Here [on the East Coast] it doesn’t have the right moisture or the right temperature.”

Munkvold disagreed with the claims that corn treated with Beauveria is safer for human consumption.

“It’s interesting because people are really worried about Bt toxin, which is toxic to insects but not mammals,” he said. “And yet Beauvaria basically has the same kind of situation of producing the chemicals that are toxic only to insects, so it doesn’t make it any safer than Bt corn.”

Munkvold said the Food and Drug Administration oversees the testing on transgenic organisms, such as Bt corn, although the testing is provided by the company itself or may be contracted through a university or private firm.

“I think this system is one of the things people criticize because they don’t trust companies to do the safety testing properly,” he said.

The recent dispute about the safety of StarLink corn pertains to a protein that was not found in any other brand of Bt corn, Munkvold said.

“The Bt protein in StarLink corn could not break down as rapidly in the digestive system as others do,” he said. “Because of this, it has a greater potential to cause an allergic reaction, but there is no evidence that it has ever done that.”

StarLink is only one brand of Bt corn, but Yield Guard is responsible for between 80 to 90 percent of Bt corn on the market, Munkvold said.

He said the reason StarLink was used for human consumption was that it had been accidentally mixed.

The current system of buying and selling corn does not make it possible to keep it separate, Munkvold said. Even when farmers follow the rules, there is still a chance of cross-pollination from surrounding fields, he said.