Sushi was once a rare treat in the U.S. But nowadays you can grab a tuna roll anywhere from the airport to your local drugstore.

How safe is it to get your raw-fish fix just steps from the shampoo aisle? Safer than you'd think.

Who's making it
If there's no sushi chef out front, an outside facility is likely sending it in. The largest such supplier is Fuji Food Products, which ships sushi to some Target, Walgreens, and Trader Joe's stores, among other chains. At six factories countrywide, machines turn out rolls that are then sent to their destinations several times a week. Like any food purveyor, Fuji is held to safety standards set by the U.S. Food and Drug Administration (FDA).

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Why it's probably safe
Whether it's made in-house or by a machine, convenience sushi isn't really any more dangerous than potato salad, cold cuts, or other prepackaged foods. "We worry about eating raw fish, but" — aside from a rare bacterial outbreak — "we haven't seen problems with it the way we have with E. coli and salmonella in burgers and chicken," says O. Peter Snyder, president of the food-safety consulting group Hospitality Institute of Technology and Management.

In fact, your tuna roll is more likely to get stinky and unappetizing from spoilage than it is to be contaminated by dangerous pathogens, Snyder says. (Of course, if it smells bad, throw it away.) Surprisingly, the fish doesn't pose the biggest safety risk: The rice does. "If rice is left at room temperature for about eight hours, a bacteria called Bacillus cereus will grow in it, which can make you ill," Snyder says. That's why sushi rice typically is prepared with vinegar.

"When rice is acidified to 4.2 pH, Bacillus cereus can't germinate," Snyder explains.

Bottom line: Shop smart, and you can enjoy to-go sushi with confidence.

Tips for the wary
Any food is potentially harmful if not handled correctly, so follow these guidelines when you're shopping for sushi on the go:

Use your eyes. You likely won't get sick from sushi that's been in the case for a couple of days, but it won't taste great — think dry, hard rice — or look great, either. "You can tell a lot about freshness by the color and texture of a piece of fish," says Brendan Hayes, retail director at The Lobster Place, a fish market and eatery in New York City. "Does it look dry, or does it have that natural glistening quality?" Search, too, for a sushi vendor with high turnover, where the cases are refilled constantly and boxes are being purchased at the same pace.

The fridge is your friend. Packaged sushi is required by the FDA to be refrigerated. If it's not, don't buy it.

Check the sell-by date. Don't eat sushi after that point in time. Period. (In general, raw fish that's refrigerated is safe for three days. Sushi made from cooked fish or vegetables can be eaten up to a full week after it was made if it's stored at or below 41º F, or about five days if your home fridge is set to a warmer 45º F.)

The "pink slime" of fish
In April, scrape tuna — a yellowfin tuna product made by scraping meat off the bones on the back of a fish, and used in sushi, ceviche, and other fish dishes — was linked with a salmonella outbreak. Nearly 400 people in 27 states got sick. (Fuji Food was not involved in the outbreak.) "Making scrape tuna requires a lot of hand contact, and a lot of surface area is exposed to the air, so it has a higher chance of contamination than a solid slice of fish," food safety expert Snyder says. If you're worried, avoid spicy tuna rolls and others made of chopped-up fish bits.