They were always pretty random, anyway. Just use your nose to tell you if it's good or bad. And even then, you can usually just cook it.

Walk into a grocery store, and you’ll face a cacophony of expirations dates: “sell by,” “use by,” “freeze by.” Sometimes you’ll even see “enjoy by” or “delicious if used by.”

The confusion over food expiration dates is more than just an inconvenience for shoppers. All that bad labeling means a lot of good food goes to waste, as consumers misinterpret dates and throw away refrigerators full of edible food.

Except for infant formula, the United States lacks the sort of national standards for food expiration dates that many other countries have. The absence of federal legislation has led to a hodgepodge of conflicting state laws, with food producers in many cases slapping whatever dates and phrasing they want onto their products, experts say.

“There’s a lot of confusion among both consumers and, frankly, people who work in the food industry,” said Dana Gunders, executive director of the anti-food waste nonprofit ReFED.

As a result, an estimated 80 million tons of perfectly usable food go uneaten, according to the group, with broad environmental consequences. Global food loss and waste equals 8 to 10 percent of all greenhouse gas pollution, according to the U.N. Intergovernmental Panel on Climate Change.

“There are so many things we need to do to decarbonize,” said Emily Broad Leib, a Harvard Law School professor and founding director of the Harvard Law School Food Law and Policy Clinic. “But this should be one of the easy ones.”

Some members of Congress are trying to change that dizzying nomenclature. Last week, a group of lawmakers — Reps. Chellie Pingree (D-Maine) and Dan Newhouse (R-Wash.) and Sen. Richard Blumenthal (D-Conn.) — reintroduced a bill called the Food Date Labeling Act meant to reduce food waste by standardizing date labels on food products.

Until Congress acts, here’s how to understand all dates and cut down on food waste:

Know what food labels really mean

In the United States, most dates consumers see on food items are for freshness, not safety, according to the U.S. Department of Agriculture. A product past its “best if used by” date may not taste as good as something fresh off the shelf. But it is often perfectly healthy to eat.

“Stale cereal is still safe to eat,” said Andrea Collins, senior specialist at the Natural Resources Defense Council. “So people are prematurely tossing food that could be really nourishing us instead.”

Some food makers measure the rate at which bacteria grows on food, or conduct taste tests to see when food begins to taste stale. But others just make an educated guess at how long a product will remain fresh-tasting.

“Most of them are manufacturers’ best guess at quality,” Collins said.

Follow your nose

If you can’t trust dates printed on packaging, what can you trust? Your own senses are often good enough, experts say. Thousands of years of evolution have given humans the ability to sniff out spoiled milk or spot green, moldy bread.

“Think back to your grandmother,” Gunders said. “There weren’t dates on food then, but they managed to figure things out.”

Here’s how long those condiments in your fridge and pantry are supposed to last

Take yogurt. After a few days in the fridge, it may smell fine but get watery at the surface. “That doesn’t mean it’s not safe to eat,” Gunders said.

Still, there are some exceptions. For instance, people can’t taste or smell a type of foodborne bacteria called listeria, which is particular dangerous during pregnancy and for the elderly. The microbes can survive refrigeration and even freezing. That means you should think twice before eating food that can harbor the pathogen, such as deli meats and ready-to-eat sandwiches that are past their date.

Heat and cold are your friends

Go ahead and sauté that slightly wilting spinach. Your stove should cook away most pathogens, according to Gunders. “If it looks fine, smells fine, but it’s past the date, you’re a little bit nervous — just cook it,” she said.

Food that is about it to hit its expiration date can just be thrown in the freezer to last longer, too. “Your freezer is like a magic pause button,” Gunders said, allowing food to retain its flavor and last much longer than normal.

Broad Leib uses hers all the time, too. “We have a little bag in the freezer with all the little random pieces of fruit that we’re saving for smoothies,” Broad Leib said.

Onward and upward,