Washington, D.C. - The debate over labeling food products that contain genetically modified crops ignores a fundamental reality: Corn pollen can be carried by the wind for up to six miles.

"It's not just what you do. It's what your neighbor is doing" when it comes to farmers' identification, segregation and labeling of biotech crops, said Iowa State University agronomist Walter Fehr.

Plant pollen can travel from field to field and farm to farm. A single field of bioengineered corn can contaminate fields of conventional corn over a wide area, said the director of ISU's Office of Biotechnology. Separating farmers into those who plant bioengineered seeds and those who don't is increasingly meaningless, Fehr said.

Agriculture is a "neighborhood," he said.

"I might say as a farmer I don't want to mess with StarLink," Fehr said, referring to the unapproved corn variety discovered in Taco Bell taco shells. "But if my neighbor is going to grow it, then I have a problem."

The latest biotech dispute began two weeks ago when a group opposed to genetically modified food said tests had turned up traces of StarLink corn in taco shells made by Kraft Foods for distribution in grocery stores under the Taco Bell brand name. StarLink corn, the group noted, is approved by the Environmental Protection Agency as an animal feed but not as human food, because it contains a protein that can cause an allergic reaction in humans.

Aventis CropScience, which produces StarLink, says it expects to receive approval for human consumption. Meanwhile, the company said, it has stopped sale of the modified corn until getting EPA clearance.

Kraft Foods recalled the products a week ago and urged the federal government to tighten control over the segregation of genetically modified crops.

The Biotechnology Industry Organization, which represents biotech companies, sent a letter to President Clinton asking that no grain products "improved through biotechnology" be allowed to enter commercial markets unless they are approved for both animal feed and for human consumption. Michael Phillips, executive director of the group, said the industry also backs "ensuring that validated test methods for grain are in place" and that government regulation is "appropriate, comprehensive and mandatory."

Scientists in the United States and other countries have shown biotech crops are safe, said David Boettger of Harlan, Ia., president of the Iowa Corn Growers Association. "It is a science that helps us in our production by using less pesticide and in growing better products more economically," he said. "But the challenge of having unhappy consumers is something we can't keep having." "We're kind of in between. So, the emotional battle we have to fight in the public perception arena is very difficult," Boettger said.

Statisticians say 30 percent of Iowa corn acreage was planted this year with genetically modified seeds. Most are engineered to include a bacterium toxic to the corn borer, an insect that must otherwise be controlled with pesticides. Fifty-nine percent of Iowa's soybean acreage was planted with varieties genetically modified to permit spraying of Roundup herbicides so that weeds can be controlled without damaging soybean plants. Up to two-thirds of U.S. processed foods, including dairy products, are estimated to have some link to genetically modified crops.

ISU's Fehr said developing accurate tests for detecting genetic engineering in crops is a major challenge. Other questions, he said, include which foods should be tested and what the tolerance levels should be for biotech material in each product. For example, should hamburger be labeled if the cow ate genetically modified corn, even though the engineered organism is eliminated in the animal's digestive system? Should a taco shell produced from bioengineered corn have a tolerance standard of 5 percent? One percent? Zero? "If you accept that there will always be some level of contamination," said Fehr, "then you have to set up a standard of tolerances. But at what level will the public be satisfied? You can't have zero tolerance."

Iowa State economist Michael Duffy said the dust-up over StarLink and Kraft's taco shells "does not by itself mean a whole lot" since the Aventis corn variety was planted on a relative few acres. Fehr said Iowa State Extension Service officials are trying to determine if any StarLink was planted in Iowa. Officials have said that only about 0.4 percent of the U.S. corn crop was planted with StarLink seed. "It is more fuel for the fire" of controversy over bioengineered foods, Duffy said of the taco shell controversy.

The costs Kraft will incur in recalling the taco shells will also "fuel the fire of reluctance on the part of companies" to utilize bioengineered food ingredients, he said. "They may decide, 'To heck with it," " Duffy said. "The drums are beating in the background," Duffy said, referring to the still small but growing opposition to genetically modified crops among environmental and consumer groups. "They will be watching every move."

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