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Admit it: When you see milk past the "sell by" date in your fridge you're apt to skip the smell test and throw that stuff out. What you might not know is that the date is actually meant for store stockers to keep track of product rotation. It offers little indication of when the milk may actually sour. You wouldn't be alone in tossing out perfectly good milk. Nine out of 10 Americans needlessly throw away edible, unspoiled food based on "use by," "sell by," and "best before" labels, according to a report released Wednesday by the Natural Resources Defense Council and Harvard Law School.

The problem of wasted food is serious and multifaceted. As Kiera Butler reported earlier this week, a whopping one-third of the global food supply is wasted. Not only that, but this discarded food is responsible for 3.3 gigatons of greenhouse gas emissions. If food waste were a country, it would be the third worst carbon-emitting country on the planet after China and the United States, according to the U.N.'s Food and Agriculture Organization [PDF].

Here in America, we're even worse: Roughly 40 percent of our food goes uneaten, amounting to an economic loss of $165 billion a year, the NRDC reported in 2012. The authors of this week's analysis found that much of that waste is due to "misinterpretation" of the date labels.