When it comes to being strict about “sell by” and expiration dates, you might think that you only have to be concerned about the perishables in your refrigerator. However, as it turns out, the time runs out on quite a few of the items you have in your dresser as well. That could potentially include your underwear. That’s right, a recent piece published by Refinery29 has revealed that the thongs, boxers, boy shorts, and panties you have, might need to be tossed out after a certain amount of time.

Speaking to Dr. Philip M. Tierno, a professor of microbiology and pathology at the New York University School of Medicine, Refinery found that “there’s about one-tenth of a gram of poop in the average pair of ‘clean’ underwear.”

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Yuck, right?

According to Tierno, “washing machines may not kill all the organisms.”

Speaking about underwear, Tierno says there’s no germ-related reason to toss out old underwear as long as you’re washing it regularly and after every use. “As long as you’re washing and disinfecting your underwear, and they’re mechanically functional, with no holes, and they’re not soiled, you can keep those,” Tierno explained. “When they become frayed or the elastic stops working, you’ll know to replace them.”

The inoculum effect, which means it takes a certain amount of organisms to cause an infection,” he went onto explain. “Your machine won’t leave behind enough microbes to create a problem for you, Tierno says. If you want to be extra careful, disinfect your washing machine by running a bleach cycle with no clothes on a monthly basis, to make sure it’s not collecting extra bacteria, he recommends.”

Tierno pointed out that to properly clean your underwear you should toss them in a washing machine with a detergent that contains peroxide.

Tierno says that you should check the label of your underwear to find out the hottest setting to wash your clothing.

“Washing machines may not kill all the organisms, but there’s another phenomenon, the inoculum effect, which means it takes a certain amount of organisms to cause and infection,” he explained. “Your machine won’t leave behind enough microbes to create a problem for you, Tierno says. If you want to be extra careful, disinfect your washing machine by running a bleach cycle with no clothes on a monthly basis, to make sure it’s not collecting extra bacteria, he recommends.”