Where Does Dinner Come From?

The grocery chain Wegman's has gotten a flood of questions from shoppers lately, concerned about foods from China and elsewhere, CBS News transportation and consumer safety correspondent Nancy Cordes reports.

"My favorite is the woman who said that 'I want to know what the pig ate before it became a pork chop,'" said Mary Ellen Burris, senior vice president of consumer affairs for Wegman's Food Markets.

Figuring out where your food was grown is not always easy — even for an expert like Joe Mendelson.

"We don't have a sticker, so we don't know," Mendelson said while picking up a package in a supermarket. "We don't know where this watermelon came from."

Mendelson, who works for the Center for Food Safety, says there are some rules of thumb.

"Pennsylvania is the state of the mushroom," he said. "Most greens are from California; we know bananas aren't grown in the United States … none." Most come from Central America or South America.

China supplies almost no fruit or fresh vegetables to the United States — but 64 percent of our imported vegetables come from Mexico and 21 percent from Canada.

"In theory we are supposed to be over making sure that the food safety agencies and governments of those countries are doing their job. But in reality, we can't hit all those places and we don't know," said Mendelson.

Leave the produce aisle and things get even more complicated.

"So we got the canned green beans here. Now, you are not gonna get any information where those green beans are from," Mendelson said while strolling down a produce aisle. "You got 'packed from fresh green beans.' Well, one would hope that green beans in the can are packed from actual green beans!"

Seafood the only product that must by law have a country-of-origin label.

"Here we go: farm-raised shrimp from Ecuador," Mendelson said. "Farm-raised shrimp from South America is something, frankly, you should be cautious about."

Since the scares over pet food and toothpaste, Wegman's has been pressing suppliers for more details on ingredients and scheduling more inspections of foreign farms.

"There are good suppliers in China and not-so-good suppliers in China and Vietnam and the rest of the world," said Burris. "It is our responsibility to know the difference."

Fresh produce from abroad is a necessity, she adds, when Americans want it year-round — and they want it cheap.