As genetically modified (GM) crops become more prevalent throughout the food industry, public policies controlling their use continue to evolve. In fall 2000, that evolution was accelerated by StarLink, a genetically engineered field corn. A cross-contamination problem, and the resulting controversy, brought to light the challenges faced by corn farmers, grain dealers, and regulators in segregating gm from non-gm grains and understanding the significance of the gene flow that can result from inadequately separated crops.

The controversy began when small amounts of genetic material from StarLink corn, which was designed to resist insects such as European corn borer, were found in taco shells from Taco Bell and Safeway supermarkets. Because StarLink was approved only for animal feed and not for human consumption, these taco shells were subjected to a Class II recall, used when a food has an adulterant but doesn’t pose a serious risk to human health. StarLink corn contains a protein called Cry9C, which could be an allergen in humans, although tests to date show no evidence that ingesting trace amounts of the protein would cause harm.

How did StarLink corn, which was meant for animal feed, end up in taco shells? It was a result of pollen drift, a concern related to all genetically engineered crops.

When Aventis, the company that produces StarLink, sold the seed to farmers, it required the farmers to sign agreements saying they would use the corn only for animal feed. Farmers planting StarLink also had to keep a 660-foot buffer strip to prevent StarLink from spreading its genes to other corn during pollination. After the cross-contamination problem came to light, some farmers reported they weren’t told that the corn was not meant for human consumption and didn’t receive the instructions about buffer strips. Others may have bought the seed from dealers or representatives who didn’t emphasize the restrictions. Still others might have simply not read the instructions carefully. Whatever the reasons, some StarLink got mixed in with other corn for human consumption, spurring public debate about the safety of gm crops and the regulations controlling them.

“Since nearly all of the corn grown in Pennsylvania is used for feed, we’ve avoided much of the serious controversy surrounding the StarLink corn crisis in the Midwest,” says Greg Roth, associate professor of agronomy. “Nevertheless, our state, as well as the corn industry nationwide, has felt the impact of the StarLink situation. Japan turned to countries other than the U.S. for some of its corn imports. And because of liability issues associated with releasing a corn hybrid that’s not approved for all commercial uses, some transgenic rootworm-resistant corn hybrids have been delayed for market approval. In the future, hybrids will probably have to be approved for both food and feed uses before they’re launched.”

The seed industry has also been affected by StarLink. When the StarLink gene was discovered in other corn, USDA issued a call to test all lots of commercial corn seed in the United States. Small amounts of the StarLink genes were found scattered throughout the industry, and USDA agreed to purchase the contaminated lots to keep StarLink off the market.

“The StarLink experience has demonstrated that it takes careful management to keep unapproved corn out of the grain trade,” Roth says. “Once grain handling facilities are contaminated, it will take time—some estimates say four years—for the grain to work its way through grain elevators, flour mills, and manufacturing plants. Through this crisis, everyone in the industry has certainly developed a healthy appreciation for the liability associated with mismanaging transgenic crops. There’s no question about it: managing GM crops is serious business.”

—Krista Weidner