What do those expiration dates really mean?

What’s safe -- and what should be tossed -- once the expiration date has passed.
© MSN Healthy Living // © MSN Health

Have you ever had a splitting headache and grabbed a bottle of aspirin, only to notice that it expired last month? Ever brewed a fresh pot of coffee, only to be dismayed that your dairy creamer is a few days past its suggested prime?

Most of us probably think we’re wasting too much. And it’s true. The Environmental Protection Agency’s latest annual report on municipal waste estimates Americans threw out almost 250 million tons of trash in 2010. Of that, almost 35 million tons was food.

We want to reuse and recycle. We want to do good. But what’s safe to keep around? And what should be tossed? Here, some experts weigh in on what expiration dates really mean.

-- By Michael Ko for MSN Healthy Living

1 of 15 Expiration date (Rich Pedroncelli/AP)

Medicine

A 1979 law requires drug manufacturers to stamp an expiration date on their products. This is the date at which the manufacturer can guarantee the full potency and safety of the drug.

However, many medications may still be potent for years afterward, argue the authors of a 2012 study that appeared in the Archives of Internal Medicine. Their study analyzed medications that had expired 28 to 40 years ago. They found that of the 14 drug compounds tested, 12 still contained at least 90 percent of the originally labeled amount.

“Given that Americans currently spend more than $300 billion annually on prescription medications, extending drug expiration dates could yield enormous health care expenditure savings,” says Lee Cantrell, associate professor of clinical pharmacy at the University of California, San Francisco, and lead author of the study.

2 of 15 Medication (David Sucsy/Getty Images)

Car seats

Most child safety car seats have an expiration date of between six to nine years, with the date usually embossed or printed somewhere on the base. While it may be tempting -- and financially appealing -- to keep it around for your second or third child, experts recommend replacing a seat before it expires.

Hot temperatures inside cars can weaken the plastic and other synthetic materials used to make car seats, according to a report produced by the National Safety Commission, which focuses on driver education issues. And some experts say years of wear and tear can also create cracks too small to be be seen.

New car seats can also come with better technology and improved safety standards. The National Highway Traffic Safety Administration provides a comprehensive list of car-seat inspection stations throughout the country that can check to see if your car seat is still good.

3 of 15 Woman putting a baby in a car seat (John Burke/Photolibrary/Getty Images)

Ground beef or chicken

The U.S. Department of Agriculture’s Food Safety and Inspection Service does not require dating on ground beef or poultry, and the agency advises consumers to handle meat carefully regardless of “use by,” “sell by,” or any other date.

“These dates reflect quality, not safety, and they must adhere to formatting requirements if a manufacturer chooses to display them,” says Kathy Bernard, a USDA technical information specialist. “If a product is handled properly and stored at a safe temperature, the product should still be safe, though not at its best quality, after the date passes.”

If meat is handled improperly, however -- for example, exposed to temperatures above 40 degrees Fahrenheit for more than two hours -- safety may be compromised before the date passes. Under certain conditions, spoilage bacteria that cause odd smells or excessive sliminess may double in as little as 20 minutes. While consumers can see the obvious, Bernard warns that some pathogenic bacteria that cause illness may not affect taste, smell or appearance. E. coli O157:H7, Campylobacter, and Salmonella are examples, she said.

Perhaps surprisingly, raw meat keeps its quality better than cooked meat, Bernard says. Freezing can extend shelf life.

4 of 15 Ground meat (Daniel Acker/Bloomberg via Getty Images )

Canned goods

Canned meat will keep for two to five years, if the can remains in good condition and has been stored in a cool, clean, dry place, says the USDA’s Bernard. Never store cans above the stove, under the sink, in a damp garage, or anywhere else with high or low temperature extremes.

While extremely rare, a toxin produced by Clostridium botulinum -- the main paralytic ingredient in Botox -- is the worst danger in canned foods in general. Bernard says you should never eat food from containers that show possible botulism warnings: leaking, bulging or badly dented cans; cracked jars or jars with loose or bulging lids; or any container that spurts liquid when opening.

“Don’t taste such food,” Bernard says. “Even a minuscule amount of botulinum toxin can be deadly.”

High-acid foods like tomatoes or pineapples might discolor or corrode can linings. As long as the can is fine, however, the contents should be safe to eat, although the taste, texture and nutritional value can diminish.

5 of 15 Canned products (Tim Boyle/Getty Images) )

Eggs

According to the USDA’s refrigeration and food safety guidelines, eggs in their shells can be stored between three to five weeks in the refrigerator, regardless of the date stamped on the carton.

Raw yolks can be refrigerated from two to four days, while hard-boiled eggs can last about a week, according to the USDA. Slightly beaten eggs can be frozen for up to a year, according to the American Dietetic Association. Eggs should always be stored in the coldest part of the fridge, and not in the door, to slow down harmful bacterial growth. When eggs go bad, they usually smell like sulfur.

Consumers should pay attention when eating foods made with raw eggs. Young children, the elderly and people with an impaired immune system are more at risk of illness when exposed to bacteria such as salmonella. Common foods that contain raw eggs include cookie dough, homemade mayonnaise and Caesar salad dressing.

6 of 15 Eggs (Saul Loeb/AFP/Getty Images)

Milk

It’s easy to throw the milk out when you swirl the carton and see chunks. But what about after the expiration date’s passed, and yet the milk smells fine?

“Nearly two-thirds of Americans needlessly discard a quarter-gallon of milk each month,” Ethel Tiersky, the editor of Shelf Life Advice, said in a 2011 New York Times article.

As with most food products, the expiration date for milk refers more to quality rather than specific safety concerns. And as with meat and eggs, the bacteria that make food look and smell bad are different from the bacteria that cause illness.

The pasteurization process, which involves heating the milk to high temperatures, destroys most of the harmful bacteria in raw milk. So trust your senses and not the expiration date, experts say. If you’re a true saver, turn old milk into cheese. Find recipes online.

7 of 15 A woman shopping for milk (Paul Burns/Getty Images)

Batteries

The expiration date on a battery is usually an indicator of shelf life, which, for some manufacturers, is a specific amount of power that the battery is expected to retain over a specific amount of time.

For example, Energizer’s L91 1.5-volt, AA lithium battery has a shelf life of 15 years, which means if stored for that long at 70 degrees Fahrenheit, it will keep 90 percent of its energy. Some manufacturers also include date codes. A “KB” on a coin lithium battery made by Energizer for toys and watches indicates it was made on January 2013 and has an expected shelf life of eight years.

Temperature and humidity can affect battery life. Experts suggest storing batteries in cool, dry locations.

“A battery is a device that is able to store electrical energy in the form of chemical energy, and convert that energy into electricity,” says Antoine Allanore, assistant professor of metallurgy at the Massachusetts Institute of Technology. So, variations in the actual chemistry and components can also factor into how long a battery lasts.

8 of 15 Batteries (Justin Sullivan/Getty Images)

Makeup

Like expired food, old makeup can harbor harmful bacteria.

“You don’t really want to be applying bacteria directly to your skin, especially your face,” says Maria Del Russo, editor at bellasugar.com. “You can cause breakouts, infection, irritation, a whole host of messy disgusting problems.”

The manufacturer’s recommended shelf life is marked on the packaging, often shown in a little makeup pot, noted with a number next to an M (months) or Y (years). After opening a makeup product for the first time, Del Russo suggests figuring out the expiration date based on the recommendation and writing it on a little piece of tape you can stick directly on the container. That way, you’ll know exactly when to throw it out.

According to Del Russo: powders are good for about two years; cream-based products, between 12 to 18 months; lipstick, about a year; and pencil eyeliners, about two years.

9 of 15 Makeup (Adrianna Williams/Getty Images)

Condoms

Condom manufacturers say their products should last for about four to five years if kept sealed in a cool, dry place. Some condoms enhanced with spermicide, which kills sperm, are guaranteed for less than that. Think of it as medicine that loses its potency and effectiveness over time.

If a condom is stored someplace warm or hot, or stuck in a wallet for a long time, it could lose its flexibility and strength.

“It’s not a good idea to use an expired condom because expired condoms are more likely to break, which can result in pregnancy and sexually transmitted infections,” according to the Planned Parenthood website. “But it’s better to use an expired condom than to use none.”

10 of 15 Condoms (William B. Plowman/Getty Images)