The Food Journal and Food, Nutrition & Science

An alliance between The Lempert Report and The Center for Food Integrity

Reusable Bags

Reusable Bags

Food Safety Update

September 26, 2010

More and more consumers are switching to reusable bags when doing their grocery shopping, and this is a good thing. After all, plastic bags take up to 1,000 to decompose in a landfill, and using them costs retailers billions of dollars. But in the rush to convert shopper habits, some basic food safety tips have gotten lost in the shuffle.

Researchers at the University of Arizona and Loma Linda University collected 84 shopping bags from consumers in the San Francisco Bay area, greater Los Angeles and Tucson, Arizona and tested them for germs. Nearly all bags contained large numbers of bacteria, and half contained coliform bacteria. A similar study, recently conducted at Texas Tech University, tested reusable bags and found that half of the bags contained coliform and a quarter of the bags contained E.coli.

In the U of A study, E.coli were identified in 12% of bags. Interviews with customers indicated that they rarely, if ever, washed their bags, even after transporting raw meats. Only 3% of consumers washed their bags; 97% did not. Also, few people (25%) separated their fresh vegetables and fruits from raw meats, and often carried them in the same bag. 

Further investigation found that car trunk storage for reusable bags, post use, led to further bacteria growth. In fact, within two hours of storage in a hot car, bacteria from meat juices increased ten-fold. And many consumers used their unwashed reusable bags for things other than food shopping, like other shopping (57%), clothes (19%), and biking supplies (5%).

The results of these studies suggest that reusable bags, when not washed or used properly (i.e. separating raw meats from produce), could play a significant role in the cross contamination of foods. With an estimated 76 million cases of foodborne illness hitting the U.S. each year, it is important, says researchers, to alert consumers to some basic reusable bag food safety procedures.

Hand or machine washing of reusable bags was found to reduce the bacteria in bags by more than 99.9%, so washing of the bags is key, especially if they are multi-purpose. Additionally, it is recommended to replace reusable totes when they wear out. Also, raw meats that are leaking should be avoided entirely. 

“Reusable bags can get contaminated with bacteria from meat juices and also from produce. Food debris gets in the bag, and the bacteria can grow. We should communicate to consumers that they should separate raw meat products from raw vegetables and wash their bags that carry both of these products after every use,” says Dr. Chuck Gerba, study co-author.