The FDA itself is part of a new effort to improve nutrition information on processed foods.

In the European Union and Japan, it is nearly impossible to find genetically modified foods, largely because laws require labeling, said William K. Hallman, director of the Food Policy Institute at Rutgers University. "No one wants to carry products with such a label," he said. "The food companies figure that consumers won't buy it."

There is nothing to stop salmon producers or food makers in the United States from voluntarily labeling their products as genetically engineered - except a fear of rejection in the marketplace, Hallman said. "I don't know of a single company that does that," he said.

The FDA maintains it can only require labeling if a genetically engineered food is somehow different from the conventional version - if it has an unusual texture, taste, nutritional component or allergen, for example.

Although some consumer advocates maintain there are important differences, the agency's scientists have already said they see no "biologically relevant" variations between the AquAdvantage salmon and traditional salmon.

Consumers could be certain of getting the non-modified version if they bought salmon labeled as "wild," but most salmon consumed in this country is farmed.

Ever since the FDA approved the first genetically altered material for use in food in 1992, when Monsanto developed a synthetic hormone injected into cows to increase milk production, the agency has held that it cannot require food producers to label products as genetically engineered.

In the intervening years, the use of genetically engineered crops has skyrocketed; 93 percent of this year's soybean crop is genetically engineered, according to the U.S. Agriculture Department.

Byproducts of those crops - soy lecithin, for example - are found in thousands of processed foods from chocolate bars to breakfast cereal; none is labeled as containing genetically modified ingredients.

No 'Hormone Free' either



The labeling matter is further complicated because the FDA has maintained a tough stance for food makers who don't use genetically engineered ingredients and want to promote their products as an alternative. The agency allows manufacturers to label their products as not genetically engineered as long as those labels are accurate and do not imply that the products are therefore more healthful.

The agency warned the dairy industry in 1994 that it could not use "Hormone Free" labeling on milk from cows that are not given engineered hormones, because all milk contains some hormones.

It has sent a flurry of enforcement letters to food makers, including B&G Foods, which was told it could not use the phrase "GMO-free" on its Polaner All Fruit strawberry spread label because GMO refers to genetically modified organisms and strawberries are produce, not organisms.

It told the maker of Spectrum Canola Oil that it could not use a label that included a red circle with a line through it and the words "GMO," saying the symbol suggested that there was something wrong with genetically engineered food.

"This to me raises questions about whose interest the FDA is protecting," said Rep. Dennis J. Kucinich (D-Ohio), who has introduced legislation that would require labeling for genetically engineered food. "They are clearly protecting industry and not the public."

One state with a sizable salmon fishing industry - Alaska - passed a law in 2005 that requires labeling of any genetically engineered fish sold there.

"One side of the argument says let's give consumers sovereignty over their food choices," Hallman said. "The other says we've done the science on this and it's no different, so if we put a label on it, we're implying it's somehow risky and that's like government imposed false advertising."