Is there bacteria in your reusable bags?

Tracey had some great questions in response to Tuesday’s post about the overproduction of reusable bags:
1. How sanitary are they for food?
2. Should they be washed?
3. Do they hold up in the laundry?
Honestly, although I’ve been using reusable bags pretty consistently for more than a year now, I never thought about washing them. My less-than-strict habits — brace yourself for the bad news, ya’ll — means my reusable bags are probably teeming with bacteria.
The Canadian Environment and Plastics Industry Council did a study in 2009 that found reusable bags are a breeding ground for mold, yeast and bacteria. Moisture from fresh produce and juices from meat can combine in the dark, warm crevices of a bag to create one big mess of contamination. And, like mine, most of the bags in the study had never been washed by their owners.
A stateside study conducted in 2010 showed similar results, but NPR’s health blog, Shots, has a decidedly upbeat take on the matter:

Dr. Susan Fernyak, director of San Francisco’s Communicable Disease and Control Prevention division, tells Shots, “Your average healthy person is not going to get sick from the bacteria that were listed.”

Regardless, it’s probably best if you wash your reusable bags, and experts suggest you do so after every use.


Of course, it gets more complicated than just throwing them into the washer with your kid’s soccer jersey. Most bags sold at grocery and retail stores like Walmart are made of nonwoven polypropylene, which is not recommended for the wash. Instead, experts suggest handwashing these bags in a warm, antibacterial soapy bath.
And then you run into the problem of drying them. The Canadian study made this observation:

Reusable bags can in principle be cleaned, but drying them out thoroughly is problematical and their flimsy nature deters scrubbing that would remove organic deposits. Any imperfect cleaning would tend to add water to incompletely removed food material and thus inadvertently boost microbial growth… At very least, if people do choose to wash their bags, it is critical that they not lay them flat to dry but instead turn them inside out and suspend them in order to properly air them out. This will avoid the creation of a moist habitat for bacteria, mold and yeast.

So where does that leave us?
1. Yes, reusable bags can grow bacteria, mold and yeast, all of which you probably don’t want rubbing up against your groceries.
2. Yes, the bags should be washed regularly. Some say after every use.
3. No, most bags are not recommended for the washer or dryer.
To find out more:
Watch a video to see if your reusable bag is cleaner or dirtier than a toilet.
Read the 2009 study done by the Canadian Environment and Plastics Industry Council. (Unless you want a throwback to high school lab reports, scroll down to page six for the observations and conclusions)
Read the 2010 study funded by the American Chemistry Council. (This one is a little easier to read, including its graphs).
Get tips on cleaning your bags, based on which material they’re made of.
Learn how to prevent cross-contamination of your bags.

Sarah Chain

I'm an avid reader and book lover living and working in downtown York. Follow me on Twitter at @sarahEchain.

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2 Responses

  1. Tracey says:

    Thanks for the information Sarah. Looks like we just can’t win.

  2. Nirav Shah says:

    i would suggest bio degradable bags as a solution tgo his mess

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