Photo: Kristin Roach, Flickr
The study, conducted by researchers at the University of Arizona, Tucson and Loma Linda University in California, found "large numbers" of bacteria in every reusable bag they tested. E. coli, specifically, was found in about 12 percent of the bags examined.
More after the jump... Through interviews with shoppers carrying reusable bags, they also discovered that only a small number -- just 3 percent -- wash their bags, and that the bags are often used for multiple purposes.
The researchers grimly assessed that, "reusable bags can play a significant role in the cross contamination of foods if not properly washed on a regular basis."
So, if you want your reusable bags to be filled with a bounty of food, and not a bounty of bacteria that can cause foodborne illness (of which there are about 76,000,000 cases of in the United States every year), you'll need to wash them. Hand or machine washing, the study notes, reduces the bacteria in bags by more than 99.9 percent.
Washing is so effective, in fact, that the researchers recommend stores be required to put printed instructions on reusable bags "that they be washed between uses or the need to separate raw foods from other food products."
Libba Letton, a spokesperson for Whole Foods, said the grocery chain does not require such instructions on the reusable bags it sells, and she's not certain they're needed.
"It's not surprising to find out that bags need to be cleaned every once in a while," Letton said. "Like all reusable items, reusable bags need to undergo some reasonable care to ensure cleanliness."