WASHINGTON — The federal government has proposed relaxing its rules on labeling of irradiated foods and suggested it may allow some products zapped with radiation to be called "pasteurized."

The Food and Drug Administration said the proposed rule would require companies to label irradiated food only when the radiation treatment causes a material change to the product. Examples include changes to the taste, texture, smell or shelf life of a food, which would be flagged in the new labeling.

The technique kills bacteria but does not cause food to become radioactive. Recent outbreaks of foodborne illness have revived interest in irradiation, even though it is not suitable for all food products. For example, irradiating diced Roma tomatoes makes them mushy, the FDA said.

The FDA last week also proposed letting companies use the term "pasteurized" to describe irradiated foods. To do so, they would have to show the FDA that the radiation kills germs as well as the pasteurization process does. Pasteurization typically involves heating a product to a high temperature and then cooling it rapidly.

In addition, the proposal would let companies petition the agency to use additional alternate terms other than "irradiated," something already allowed by the Farm Security and Rural Investment Act of 2002 but that no firms have pursued, according to the FDA.

The FDA posted the proposed revisions to its rules on irradiated foods on its Web site Tuesday, a day before they were to be published in the Federal Register.

FDA will accept public comments on the proposal for 90 days. A consumer group immediately urged the FDA to drop the idea.

"This move by FDA would deny consumers clear information about whether they are buying food that has been exposed to high doses of ionizing radiation," Wenonah Hauter, executive director of Food & Water Watch, said in a statement.

The FDA acknowledges in the proposed rule that allowing alternative ways of describing irradiation could confuse consumers: "Research indicates that many consumers regard substitute terms for irradiation to be misleading," the proposal reads in part.

But the requirement that the new labeling explain why a product was irradiated should clear up some consumer confusion, said Barbara Schneeman, director of the FDA's office of nutrition, labeling and dietary supplements.

"You would be told the material fact: what is it about this product that is different from some other product," Schneeman said. If a food were irradiated but left unchanged and indistinguishable from an identical but unradiated product, it wouldn't have to be labeled, she added.