[FACT OR FAKE #55] Does Freezing Your Jeans Really Clean Them Of Bacteria?

The CEO of Levi Strauss & Co. says that people don't need to wash their jeans and has previously said that freezing your jeans can help kill odor-causing bacteria, but some people are skeptical.

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On Tuesday, the CEO of Levi Strauss & Co., Chip Bergh, claimed that jeans do not need to be washed; the pair he wore at that time, he said, had "yet to see a washing machine" in the past year

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Chip Bergh, CEO of Levi Strauss & Co. mentioned that more than a year had passed since he washed the very pair he was wearing as he spoke at Fortune’s ‘Brainstorm Green’ conference on sustainability. He said leaving the jeans out of the laundry saves water and suggested too much washing breaks down the denim.

“These are one of my favorite jeans, maybe a year old, and they have yet to see a washing machine,” Bergh said proudly. “If you talk to real denim aficionados, they’ll tell you, don’t wash your blue jeans.”

"We are the ultimate in sustainable apparel," Bergh said. "If you buy [our jeans] they will last a lot longer than most people's waistlines will." WATCH:

The statement has gotten people talking until they’re blue in the face, or, as the Daily Beast put it, "people are freaking out"

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The idea is that by washing their jeans very rarely, customers can save water — an issue Levi's has become increasingly concerned about recently as they've tried to cut down on water consumption during their manufacturing processes.

Some of their jeans come with instructions that tell customers to "wash them as little as possible" and "throw them in the freezer to kill germs and stink" instead. Saving water is a laudable goal — and washing jeans when they don't smell is indeed wasteful. But on the rare occasions that they start to stink, there's a problem with Levi's recommended solution, which has since become internet lore.

It's not new advice, though. Designer Tommy Hilfiger has made similar comments. And CNN's Anderson Cooper told style expert Stacy London two years ago that he washes his jeans very rarely.

Jeans aficionados may be accustomed to hearing some unusual tips on keeping their denim products fresh. Advice ranges from spot cleaning jeans and never washing them to freezing them to kill any germs. Jolie Kerr, who writes a column called "Ask a Clean Person," says it depends on your lifestyle and hygiene preferences.

"Consider how you're wearing your jeans and make laundering decisions accordingly," said Kerr. "The way you'd care for a pair of jeans that you wear for yardwork versus ones you'd wear out dancing should be different -- the function should dictate how you treat a pair of jeans."

However, people who actually know a thing or two about microbes might not agree to his advice. Stephen Craig Cary, a University of Delaware expert on frozen microbes, says you shouldn't bother freezing your jeans.

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Most of the bacteria on your jeans probably started off on your own body. Since these critters are happiest living at the temperature of human skin, “one might think that if the temperature drops well below the human body temperature they will not survive,” Cary writes, “but actually many will. Many are preadapted to survive low temperatures.” And it takes only one survivor to repopulate your jeans when they warm up.

“I would suggest that you either raise the temperature to 121 degrees Celsius for at least 10 minutes,” Cary writes, “or just wash them! The latter surely is the best alternative to save energy.”

If these jeans are stinky, the freezer is not the answer.

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Cray promised that all it takes for your bell bottoms to become a bacteria-ridden mess is one resilient germ to survive the clean. He was also stationed in Antarctica at the time, so he’d probably learned a thing or two about freezing things.

Julie Segre of the National Human Genome Research Institute cautioned that washing is the best option, because it removes a build up of more than just germs

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“The bacteria that would live on your jeans on the sloughed skin and the dirt nutrients than the jeans themselves, so detaching the sloughed skin could reduce the microbial load of your jeans,” she says. In her opinion, removing the dirt and the sloughed skin is more important than removing any bacteria, though she warns that she may have “just transitioned from speaking as a scientist to speaking as a mother.”

So, should you really stop washing your jeans? Does freezing jeans makes them bacteria-clean?

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FACT: Cold temperatures aren't enough to kill off any bacteria on your clothing. So, freezing a pair of jeans is not likely to kill all the bacteria on them. Therefore, you shouldn't stop washing your jeans.

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The "germs" Levi's refers to are bacteria that live on your own skin and migrate onto denim over time, causing it to smell. Washing the denim kills bacteria, as does raising its temperature to extremely high levels — at least 121°C. But freezing a pair of jeans, alas, is not likely to kill all the bacteria on them.

Sure, overnight freezing might kill most of the bacteria. But if some remain, they'd likely be able to recolonize the denim quickly after it warmed back up. That's because the dirt and dead skin cells present in the jeans — which serve as the bacteria's substrate — are left entirely intact by freezing.

How often you wash your jeans depends on how comfortable you're with the growing amount of dirt and sloughed skin on the fabric

The bacterial load doesn't seem to be much affected by how often you go between washings. A somewhat unscientific experiment by a Canadian student found little difference in the bacterial load between one pair of jeans worn for 15 months without washing and another pair worn for 13 days.

Regardless of all this, if you want to experiment with freezing jeans for yourself, here’s a "how to" video:

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