But there had long been concern that zapping leafy greens with X-rays or other means of radiation would leave them limp. Not so with today's modern techniques.
The Food and Drug Administration determined that irradiation indeed can kill food-poisoning germs and even lengthen the greens' shelf life without compromising the safety or nutrient value of raw spinach and lettuce. The new regulation goes into effect Friday.
"What this does is give producers and processors one more tool in the toolbox to make these commodities safer and protect public health," said Dr. Laura Tarantino, director of FDA's Office of Food Additive Safety.
The Grocery Manufacturers Association had originally petitioned the FDA seeking to expand use of irradiation to many more types of produce several years ago. But in wake of the 2006 E. coli outbreak from spinach -- which killed three people and sickened nearly 200 -- plus a list of lettuce recalls, the industry group asked the FDA to rule on the leafy greens first.
The FDA still is considering what other types of produce might be OK to irradiate. Often mentioned as possible are tomatoes and peppers, which have been the focus of investigators trying to trace this summer's nationwide salmonella outbreak.
E. coli is fairly sensitive to radiation, but salmonella can require more energy. While it's not sterilization, the FDA ruled that food companies could use a dose proven to dramatically reduce levels of E. coli, salmonella and listeria on raw spinach and lettuce -- a dose somewhat lower than meat requires.
The most likely use would be in bagged greens: The entire sealed bag can go under the beam, taking away the risk of recontamination later.
Planning on irradiation isn't an excuse for dirty produce in the first place, Tarantino warned. Growers and processors still must follow standard agricultural and manufacturing processes designed to keep the greens as clean as possible. Consumers, also, should wash the leaves just like they do today.
But increasingly, the raw produce so valued for its nutrition is instead causing outbreaks because of contamination in fields or elsewhere in the chain from farm to table. The spinach outbreak, for instance, was traced to a field that had been contaminated by wild boars. That's prompting new interest in technology.
While irradiated foods initially caused some consumer concern, Tarantino stressed that the food itself harbors no radiation.
"There is no residue, there's nothing left and certainly no radioactivity left," she said.
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