This is not a semantic exercise, at least not entirely, although much of the story revolves around a word: irradiated.

This is also about things outside the world of language. Ground beef, for one thing, more than 19 million pounds of which was suspected of bacterial infection and pulled from stores last summer in two big recalls across the country. Food-borne bacteria, for another thing, estimated to cause 365,000 hospital visits and 5,000 deaths a year in the United States.

Such outbreaks of illness may or may not make news, depending on the flow of events. Either way, Giant Food has been moved to do something, and has become the first supermarket chain in this area to introduce ground beef that's been taken to a specially designed building and run through a machine, zapped electronically to kill such bacteria as E. coli and salmonella. That is, irradiated.

There's that word. What does it say to you?

Giant Food's 189 stores between Virginia and New Jersey early this month were added to the list of those in the United States selling ground beef given this treatment, which was approved by the U.S. Food and Drug Administration in 2000. That puts the number of stores offering irradiated ground beef at somewhere around 1,900. The country is now that much safer from bacteria, or, perhaps, in jeopardy otherwise. Depends on whom you ask.

This is, after all, a story about the connection between food and health, where scientific certainties can seem elusive.

Where irradiated ground beef is concerned, officials in the government and at Giant say we're as close to certainty as anyone can reasonably be. Such august entities as the World Health Organization, the American Medical Association and the Centers for Disease Control and Prevention have given their blessing to ground-beef irradiation as practiced by Giant Food.

The FDA has since 1963 approved many foods for irradiation, including eggs, sprouts, seeds, juice, fresh fruit and vegetables, spices, pork and poultry. Ground beef is considered especially vulnerable to bacteria because the grinding combines meat from different sources, heightening the risk that the meat may have been exposed to bacteria during processing.

Daniel Engeljohn, the director of regulations with the food safety and inspection service at the U.S. Department of Agriculture, firmly responds "no" when asked if any substantive questions remain about the safety of irradiation with respect to ground beef.

"It has been studied well enough on ground beef to lay to rest any concerns," says Engeljohn.

The National Consumers League, the nation's oldest consumer-advocacy group, considers irradiated beef "a measure of safety for consumers," says Linda Golodner, league president. While Golodner says there may be room for more study of irradiation, she feels the safety of irradiated food has been established by the FDA and the USDA.

Folks at the consumer-advocacy groups Public Citizen and the Center for Food Safety are not so sure. The groups say in a joint report that the FDA "has dismissed and ignored a substantial and growing body of evidence suggesting that irradiated foods may not be safe for human consumption."

Then, of course, there is John Q. Public, busily keeping daily life together while awash in endlessly swirling media reports of studies and counterstudies, half-remembered factoids and vague associations. Words, words, words.

If you walk up to folks at the Giant supermarket on York Road, for instance, and ask about this word, irradiated, you sense that the folks in the Giant public-relations department have their work cut out for them.

Some shoppers say the word irradiated makes them think of illness, of nuclear radiation, of things glowing in the dark.

In the absence of other information, says Giant shopper Allison Wolf, the word irradiated by itself "would bother me. It suggests radioactivity, but that's purely from hearing the word."

You have to be looking for it in the meat case to find irradiated ground beef, which makes up only 5 percent to 10 percent of the ground beef the supermarket chain sells. It occupies a little section in the meat case in packages marked with the message: "Irradiated for Food Safety." It costs a bit more than the regular ground beef: $3.99 per pound for the 93-percent lean, as compared with $3.69 for the same grade of nonirradiated ground beef.

Giant has printed brochures and put up signs. It has conducted demonstrations. It is touting the endorsements of government agencies and consumer organizations, including the National Consumers League and the Consumer Federation of America.

The irradiated ground beef at the Giant arrives by way of a plant run by the SureBeam Corp. in San Diego. There, the meat passes on a conveyor belt before an intense energy beam generated electronically, not by means of nuclear materials. True, the beam generates ionizing radiation, same as a nuclear source, meaning it's strong enough to break chemical bonds. Of course, cooking food also breaks chemical bonds.

Public Citizen and the Center for Food Safety say that studies conducted since the 1950s have drawn connections between irradiated foods and health problems in people and animals. Studies have turned up links to abnormal cell development in people, and in animals, fatal internal bleeding, increased prenatal deaths and immune-system changes.

Most recently, German scientists have found that cellular and genetic damage in human and rat cells can be caused by contact with a class of chemicals called -- get ready for this word -- cyclobutanones. These chemicals apparently occur nowhere in nature, but in 1971 it was established by American researchers that they appear when certain fats in food are irradiated.

On the other hand, an August 2000 report from the U.S. General Accounting Office that purports to account for 50 years of research on the subject concludes that the results "support the benefits of food irradiation while indicating minimal potential risks."

If there's the risk that the "I" word will scare customers away, some elements of the food industry are working on that. Giant Food has taken no position on this, but the National Food Processors Association has been pressing the government to allow another term to be used on labels: cold pasteurization.

Sound better?

Perhaps, but when the FDA asked consumers in focus groups about this, the consensus was most wanted it called what it is: irradiated.

No problem, says Carolyn Woods, a shopper at the York Road Giant.

"If it means purifying the beef, I'm all for it," says Woods. "I think it would be simpler if they would say 'purifying the meat.' That way no one would worry about it."