The approval comes two years after E. coli outbreaks linked to spinach and lettuce sold in grocery stores and served at various restaurants. Outbreaks of the dangerous bacteria sickened dozens of consumers and led some to be hospitalized.

In severe cases, patients developed kidney failure.

Since then, other outbreaks have affected a variety of products, most recently Salmonella contamination in hot peppers from Mexico that surfaced earlier this summer.

"In the aftermath of the recent outbreaks, FDA wanted to fast track an important tool to help industry improve the safety of fresh produce," Grocery Manufacturers Association (GMA) spokesman Brian Kennedy said.

But FDA spokeswoman Stephanie Kwisnek said the agency was making its decision now because it had finished reviewing all the necessary data.

Industry groups initially sought the agency's approval eight years ago to clear a wide variety of foods, including various meats and produce before amending their request to allow the agency to review certain foods first.

The FDA's review of the other foods is still ongoing.

Foods already approved for radiation treatment include meat, poultry, spices and molluscan shellfish such as oysters, mussels and clams, according to the agency.

About 76 million cases of E.coli and other types of food poisoning occur each year, according to the Centers for Disease Control and Prevention. Patients stricken with a food- borne illness experience a wide variety of symptoms that can include abdominal cramps, vomiting, nausea and diarrhea.

IDEAL HABITAT

Spinach and lettuce are particularly susceptible to contaminants because their textured leaves can provide "an ideal habitat" for pests and because they are usually eaten raw, the FDA said.

The agency granted the production change in response to a request by two industry groups, the National Food Processors Association (NFPA) and The Food Irradiation Coalition.

The Grocery Manufacturers Association (GMA), in a statement, said radiation offered another tool to help improve produce safety. The group merged with the NFPA after the petition was filed, GMA's Kennedy said.

The FDA's ruling could impact a variety of produce companies, including Fresh Del Monte Produce Inc, Chiquita Brands International Inc and privately-held Dole Food Company Inc, among others.

Despite the approval, it was not immediately clear if food manufacturers or retailers would soon begin using the technology amid concerns about costs and consumer reactions.

Radiating food, including leafy greens, does not appear to be dangerous, the FDA said in its notice.

"The overwhelming majority of studies showed no evidence of toxicity. On those few occasions when adverse effects were reported, FDA finds that those effects cannot be attributed to irradiation," it said.

Spinach and lettuce that have been irradiated will have to carry a special "radura" logo and state the product has been "treated with radiation" or "treated by irradiation," FDA's Kwisnek said.

But some consumer groups cautioned against thinking irradiation is the sole step needed to protect against contaminants in leafy greens and other produce.

Other measures still need to be adopted, including many at the farm level before foods are even processed, the Center for Science in the Public Interest said.

Farmers should be required to maintain a written food safety plan and the FDA should develop uniform standards for those plans and routinely inspect them, the nonprofit advocacy group said in a statement.