FDA on Thursday issued final guidance on voluntarily labeling whether foods derive from genetically engineered (GE) plants.

The development marks an express acknowledgment by FDA that at least a portion of the U.S. population is in favor of knowing whether food comes from bioengineered material.

“We recognize that some consumers are interested in knowing whether food ingredients are derived from GE sources," said Susan Mayne, Ph.D., director of FDA’s Center for Food Safety and Applied Nutrition, in a statement.

Citing consumer polls and concerns about the impact of GE foods on the environment and humans, watchdog groups such as the Center for Food Safety have appealed to Congress to mandate labeling of bioengineered foods. But lawmakers on Capitol Hill remain divided on whether food manufacturers should be required to disclose such information or whether a voluntary labeling system is the better approach.

FDA does not require labels on foods derived from GE plants. Regulators can only do so under federal law if a “material difference" exists between the GE product and its traditional counterpart, the agency said.

While FDA guidance doesn’t carry the force of law, it could provide a level of comfort to food marketers. The question of what constitutes a GE- or non-GE food has fostered uncertainty, as highlighted by a recent lawsuit that was filed against the taco and burrito chain Chipotle.

According to the complaint, Chipotle launched a multimedia campaign in April that represented Chipotle was "G-M-Over it" and that the food chain only uses "non-GMO ingredients." But Chipotle’s advertising campaign is deceptive, the lawsuit alleged, because the company serves meat products that originate from animals that feed on GMOs (genetically modified organisms), and Chipotle’s sour cream and cheese ingredients come from dairy farms that feed animals with GMOs.

Chipotle has said the lawsuit has no merit. But the case highlights the potential for disagreements over the truthfulness of non-GE statements without federal guidance.

“Although companies can always voluntarily add labeling to their products as long as it’s truthful and not misleading, these guidances provide recommended actions for manufacturers who may wish to voluntarily label their products with information about whether the foods contain ingredients from GE sources," FDA explained in a news release.

FDA offered guidance on labeling of foods that derive from GE material, as well as foods that don’t contain bioengineered plants. Examples of the latter statements include “Not bioengineered," “Not genetically engineered" and “We do not use ingredients that were produced using modern biotechnology." Other examples include “Not genetically modified through the use of modern biotechnology," “This oil is made from soybeans that were not genetically engineered," and “Our corn growers do not plant bioengineered seeds."

“FDA encourages food manufacturers to ensure that labeling terminology concerning the use of modern biotechnology in the production of a food or its ingredients be accurate and consistent and that the integrity and meaning of scientific terminology be preserved to help ensure clear communication in food labeling," the agency stated in the guidance. “Thus, FDA encourages manufacturers to use labeling claims that state that a plant-derived food product or its ingredients, as appropriate, was not developed using bioengineering, genetic engineering, or modern biotechnology."

FDA provided examples of statements that could be false or misleading when considered in the context of the whole label. The agency also encouraged industry to avoid statements such as “GMO free," “GE free" and “non-GMO."

“The term ‘free’ conveys zero or total absence unless a regulatory definition has been put in place in a specific situation," FDA explained in the guidance. “The potential challenges of substantiating a ‘free’ claim are described in Section III.D of this guidance, and in light of these challenges FDA recommends that manufacturers not use food labeling claims that indicate that a food is ‘free’ of ingredients derived through the use of biotechnology."

FDA on Thursday also issued draft guidance on voluntarily labeling whether food has been derived from GE Atlantic salmon. The issuance of the document coincided with the agency’s finding that AquaBounty Technologies’ bioengineered salmon is as nutritious and safe as food from conventional Atlantic salmon. The agency is accepting public comment on the draft guidance for 60 days starting on November 23 through instructions in the Federal Register.