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A few years ago I heard of a process where perishable foods such as milk and lettuce were bombarded with radiation to dramatically increase their shelf life. This process also killed off bacteria and vermin. Foreign countries seemed to employ this with positive results. There was talk of using this process in the U.S., with the only proviso being that the food in question be specially labeled. However, try as I might, I cannot find any radiation-treated food in my local grocery store--not that I'm eager to try it. How is food treated with radiation? Is it safe? What has happened to the process in the U.S. since the news stories first came out? --Thomas Cotrel, Burbank, California

Depending on whom you talk to, food irradiation is yet another plot to poison the food supply for profit or the victim of antinuclear hysteria. The worst fears are certainly exaggerated. Despite what many people think, the process does not make food radioactive. Pallets of strawberries, chickens, or other foods are exposed to a radioactive source, usually cobalt, for a specified number of minutes inside a shielded room. The radiation kills, or at least is supposed to kill, deadly microorganisms such as salmonella while leaving the food itself more or less intact.

It's the "more or less" part that's the kicker. Ionizing radiation, which is what we're talking about here, causes some of the chemical compounds in food to transmute into other ones. Most of the new chemicals, called "radiolytic products," are the same as naturally occurring compounds and are probably harmless. But a few may not be and, who knows, may even be carcinogenic. What's more, irradiation destroys some vitamins and other nutrients. Estimates of the amount of loss vary widely, from 4 to 40 percent, and it should be pointed out that merely cooking most foods will destroy a percentage of the vitamins. Just the same, the questions surrounding food irradiation have led a number of respected scientists to oppose the practice.

They're in the minority though. What's keeping irradiated food out of the marketplace isn't scientific uncertainty but consumer resistance--or rather fear of consumer resistance. The U.S. Food and Drug Administration has approved irradiation for a number of food items, but the industry has been nervous about putting the stuff on store shelves lest consumers go nuts.

More's the pity, say irradiation advocates. A huge percentage of world food production, as high as 50 percent in developing countries in warm climates, spoils before it can be eaten, and food poisoning is still fairly common in the U.S. and other countries. Irradiation would reduce both these problems. Maybe 20 years from now it'll be as commonplace as fluoridation. Then again, 20 years ago they thought nuclear power would make electricity cheap.

At the entrance to most underground and covered parking garages hereabouts, there are signs reading ABSOLUTELY NO PROPANE VEHICLES ALLOWED IN THIS PARKADE. Why? Is there some danger? --Glenn S., Edmonton, Alberta

There's an off chance you could cause a fire or explosion--a prospect that would definitely enliven a dull trip to the mall but makes your typical petit bourgeois garage owner break out in a cold sweat. Propane, whether used in cars or otherwise, is stored in liquid form in high-pressure tanks. Occasionally some leaks out via a pressure-relief valve or what have you--not a problem on the open road, but potentially a big problem in a confined area, since propane is heavier than air and collects at low spots, e.g., the bottom floor of an underground parking garage or the low point in a tunnel (entrances to tunnels often sport antipropane warnings). Some propane buffs, who regard the stuff as nature's perfect fuel, say the danger is exaggerated, and my search failed to turn up any documented cases of propane disasters in garages or tunnels (although wasn't there some sort of bang at the World Trade Center a while back?). Be that as it may, it's only polite to humor the worrywarts and leave your propane-powered Pontiac parked on the street.

Is there something you need to get straight? Cecil Adams can deliver the Straight Dope on any topic. Write Cecil Adams at the Chicago Reader, 11 E. Illinois, Chicago 60611, or e-mail him at cecil@chireader.com.

Art accompanying story in printed newspaper (not available in this archive): Illustration/Slug Signorino.

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