Clean your reusable bags or risk food poisoning

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July 24, 7:16 AM

Dirty bags can cause illness

Portland is considering banning single-use plastic shopping bags, but a study of reusable shopping bags shows that many people don't clean them and risk food poisoning.

The study conducted by the Environment and Plastics Industry Council (EPIC) in Toronto, Canada intercepted people on the street to test bags they were actually using.

A majority of the bags were in use less than a year, but users used them for more than just groceries, such as carrying gym clothes or books.  Almost none of the users had ever washed or sanitized the bag.

Unsurprisingly, the bags were found to harbor bacteria, molds and yeast.  This included a coliform (gut) bacteria count that was unacceptable and could lead to food poisoning.  Full reusable shopping bag study report.

An earlier study showed that bags that looked "pristine" still harbored alarming amounts of bacteria, yeasts and mold.  Clean-looking does not mean clean.

Proper Reusable Shopping Bag Cleaning
The two bags above came from my own closet, the home of a hospital clinical microbiologist and medical technologist.  The one on the right is a canvas bag that has been used for carrying gym clothes and other non-food items.  Attempts to wash the canvas bag resulted in a shrunken, misshapen bag that still has dirt stains.  The bag on the right is the common reusable bag, actually made of polypropylene plastic and labeled with washing instructions: Machine wash cold, no bleach, air dry.

Reusable shopping bags should be treated the same as kitchen cutting boards.  Use only for food items.  Meat should be encased in a second plastic bag to prevent leakage of bacteria (including Salmonella).  The bags should be rinsed with soapy water and air dried between uses, and machine washed if there has been any spillage or leakage.

Consider using separate, labeled bags for meat and produce as you do for cutting boards.

Never just fold up a damp reusable shopping bag and pop it into a dark cupboard.  That will make it an excellent petri dish to grow bacteria, yeasts and molds.

Don't Use Reusable Grocery Bags for Other Items
Using a bag contaminated with coliform bacteria such as E. coli and Salmonella from meat to carry other items will result in contaminating those items.  Pens, pencils, cell phones and other items that people put into their mouths or next to their face can carry bacteria or asthma-triggering molds.  Use grocery bags only for groceries, and sanitize them after each use.

As a medical technologist and former food handler, the reusable bags have always concerned me for their potential to be unsanitary.  Single-use bags are sterile upon first use. Train yourself to clean your reusable bags after each use.

More: Portland Considers Plastic Bag Ban




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