Food often good after expiration date

Don't toss that half gallon of milk just yet.

The "use by" or "best by" dates found on food labels -- from dairy to meat to cereals -- may actually be misleading, some advocates say. It turns out that many of these foods can last much longer and are still perfectly safe to eat.

Christina Guzman is one of millions of Americans who keeps a close eye on these labels. "I don't want to eat something that's expired," she told CBS News.

But in many instances these dates may be overkill, according to Peter Lehner, the executive director of the Natural Resources Defense Council. Lehner told CBS News it's still safe to consume foods and drinks a few days, even weeks -- and sometimes years -- after the date on the package.

"You don't need to throw it out if it's past the date on the label," he said. "The dates are up to the manufacturers, there's no federal standards for anything in this store, except for infant formula."

His organization estimates that 9 out of 10 Americans are confused by the "use by" or "best by" date labels on the foods they buy. The group found that a family of four throws out as much as $2,000 worth of edible food each year.

For the most part, he advises that if milk passes the sniff test it can be used up to week after its date. Eggs are still good for as long as a five weeks after their date. And if they aren't already opened, many canned goods can stick around as long as five years after the date.

The Grocery Manufacturers Association told CBS News that dates on foods are merely there to ensure freshness, and it admits changes may be needed to prevent unnecessary waste. The group says its goal will be to create a uniform global standard that will make it easier for grocery shoppers to interpret date labels.

Until then, Lehrner says consumers should use common sense. "You can open it and smell it. You can take a look at it and for most things you'll be able to tell whether or not it's still good," he said.