In fact, it is such a tempestuous topic that organizers of the world's largest biotechnology conference scrubbed a Canadian proposal to have a panel discuss labeling during last week's gathering here.
But that was only a prelude to Wednesday's vote by the European Parliament to require strict labeling as a condition of the European Union dropping its 5-year ban of genetically modified food. Rather than ease trade tensions with the United States, that stipulation is expected to exacerbate them.
For the U.S. biotech industry, the labeling requirements represent a de facto continued European ban on genetically modified products.
Biotechnology's vocal critics readily agree. They think European consumers will reject labeled products, and hope to also bring mandatory labeling to the United States, which has so far resisted such legislation at all levels of government.
"I think the European action marks the beginning of the end for agricultural biotechnology," said longtime critic and activist Jeremy Rifkin.
The industry argues that Europe's stand is based more on internal politics than science. It maintains that biotechnology products are safe, better for the environment than traditional crops and will someday even improve human health.
Under the European rules, which still must be ratified by member countries, all products including animal feed, vegetable oils, seeds and byproducts containing more than 0.9 percent genetically altered material must carry this label: "This product is produced from GMOs."
Companies using engineered ingredients must trace each altered product from its point of origin to the supermarket shelf.
"It's impractical," said Val Giddings of the Biotechnology Industry Organization, or BIO. "It will be impossible to monitor, hugely burdensome and expensive. Rather than facilitating consumer choice, it's more likely to drive food producers to avoid using genetically improved ingredients."
U.S. soy and corn farmers have been particularly hard hit by the EU's aversion to biotechnology crops.
Eighty percent of U.S. soy crops are engineered to withstand the spraying of a popular weed killer and 40 percent of corn crops are engineered with a bacterium's genes to kill pests.
Soy exports to the European Union have fallen from $2.3 billion annually in 1997, the year before the biotech moratorium, to half that last year. U.S. corn exports fell from $191 million in 1997 to less than $2 million last year.
There is a consensus among food and biotechnology companies that any genetically modified food label anywhere will deter consumers. Already, most large food makers don't use genetically modified ingredients in their European goods. Biotechnology companies fear the same thing could happen in the world's largest market if labeling is ever mandated in the United States.
"It's a black label," said Stephanie Childs of the Grocery Manufacturers of America. "We have to respond to the market demand." So her organization has lobbied hard against mandatory labeling.
Last year, the biotech and grocery industries spent a combined $5 million to defeat an Oregon ballot measure that would require mandatory labeling in that state.
At least two proposed laws mandating labels failed on Capitol Hill since 2000. Another bill was introduced last month by Rep. Dennis Kucinich, who is seeking the Democratic presidential nomination.
BIO and the GMA, which represents the world's largest food makers, say they support voluntary labeling, which is the Food and Drug Administration's current position.
But not a single company is known to label its products, though an estimated 70 percent of processed food in the United States contains genetically modified ingredients.
Organic companies have found a growing niche labeling their food as free from genetically modified ingredients, but even they face some trouble in European markets skeptical of all U.S. imports.
At BIO's annual convention, 16,000 international biotechnology professionals heard some 200 panel discussions on topics ranging from gene therapy to plant-made pharmaceuticals. But not an official word on labeling.
Giddings said the labeling panel simply failed to make the final cut for the busy four-day conference.
"Four out of five proposed panels got the ax for one reason or another," Giddings said. "It didn't clear our threshold."
But the Canadian regulators organizing the labeling panel said BIO yanked it well after they had begun the planning. They said indications were that BIO was pressed to skip the subject by a conference organizing committee of food and biotech executives.
One of the panelists who had been lined up, Gregory Jaffe of the Center for Science in the Public Interest, blamed the food industry.
"BIO and its food industry partners felt it was too controversial a topic to have an open discussion about," Jaffe said.