Reusable Grocery Bags

By Kristen Castillo

April 9, 2013 5 min read

Your reusable grocery bags carry bread, fruit, water and other foods, but do you know your bags could also be carrying germs and bacteria, including E. coli?

While reusable bags, which are often made up of woven polypropylene or polyester, are better for the environment than plastic grocery bags, they require more health and safety maintenance than many consumers think.

According to a 2010 study called "Assessment of the Potential for Cross Contamination of Food Products by Reusable Shopping Bags," researchers found reusable bags pose a significant health risk.

Researchers at the University of Arizona and Loma Linda University in California who randomly tested 84 reusable grocery bags of shoppers in Tucson, Ariz., Los Angeles and San Francisco found more than half the bags were positive for "coliform bacteria, including E. coli."

The study also showed that "97 percent of those interviewed never washed or bleached their reusable bags."


"Paper and plastic single-use bags represent a big threat to the environment," says Saralee Hofrichter of, a company that sells reusable bags. "Many of them end up in landfills, while the resources needed in the production of them result in toxic emissions. Reusable bags help reduce the impact of plastic bag waste, while being fashionable and practical."

Some cities have banned plastic bags, such as San Francisco, which imposed a plastic bag ban in 2007. Since many retailers won't provide plastic bags, it's up to you, the consumer, to bring your own bag -- or BYOB.

San Francisco's Board of Supervisors mandated that reusable bags in its jurisdiction must be designed to withstand at least 125 uses. With that many possible uses, unwashed bags could pose a big health hazard.

*Wash, Wash, Wash

Before you head to the store with your reusable bags, make sure they're clean.

"Washing your reusable bags is important, especially to help bacteria, yeasts and mold from growing on your bags and cross-contaminating your food," says Brian Sansoni of the American Cleaning Institute. "For instance, if you've made a lot of purchases in the meat department, the juices from the meat can often leak into your bag."

University of Arizona professor Chuck Gerba, one of the authors of that study on contaminated bags, agrees, urging consumers to "use cloth bags because they can be washed in a washing machine. You should wash them any time you have used them to carry raw meat products."

It's best to know what type of reusable bag you have so you can clean it properly. Sansoni, who recommends reading the bag's care label, gives the following suggestions on how to clean bags made from the following fabrics:

--Cotton bags. Machine wash with hot water and laundry detergent. Machine or line dry.

--Nylon/polyester bags. Hand wash in warm water and soap. Turn inside-out and line dry.

--Insulated bags. Hand wash using warm water and soap; or you can use disinfecting or antibacterial wipes to clean the bags, especially along the seams. Line dry.

--Woven/non-woven polypropylene bags. Machine wash on the gentle cycle with soap and cold water; or hand wash with soap and water. Line dry.

Hofrichter says the bags she sells are made from hemp using "low impact dyes." She recommends washing hemp bags with a gentle cycle machine wash or by hand.

*It's in the Bag!

Make sure the bags are dry before you store them. Wet or damp bags could result in mold or bacteria.

The American Cleaning Institute also suggests not storing bags in your car's trunk since the area can be a "dark, warm and often humid environment that promotes bacteria growth."

Designate specific bags for carrying meat or seafood, as well as ones for produce. Label those bags, and only use them for their label's intended use. While you still should wash all reusable bags, at least you'll know which ones have the potential for contamination and the associated health risks.

If you like reusable bags for toting non-food items like books or clothing, label those bags, too, so you don't accidently use them for carrying groceries.

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