Up until recently I hadn't ever washed my reusable grocery bags, not because I didn't think it was necessary or a good idea, but to be honest, the idea just hadn't crossed my mind. Since Alameda County now charges for bags, and word on the street is that Contra Costa county will also soon be charging, it seems I will be using more and more reusable bags in the near future.
Awhile ago Mr. L sent this article to me about the need to wash reusable bags. I promptly washed our bags, and bookmarked the article for further thought and study. Larson cites a study published by law professors at the University of Pennsylvania and George Mason University. This study claims to have found a 46% spike in San Francisco deaths during the 3 months immediately following the county wide plastic bag ban in October 2007 (2). Yikes! That seems pretty terrible. However, either I'm being incredibly dense, the numbers in this study are a little sketch, or lawyers have a very different way of reporting numbers, but regardless, after looking at this study a few times this week I wasn't able to grasp what was actually going on. I'm a little uncomfortable with the way the authors compared the before and afters, and since I'm not actually positive of anything, I'll simply be setting this study aside and looking at two published articles that are applicable to this discussion.
Perhaps many of you have been washing your bags for years-- if you think about it, it really is common sense. However, one study randomly interviewed shoppers and sampled reusable bags in California and Arizona (3). They found that reusable bags are seldom, if ever, washed, and that most bags had large amounts of bacteria, about half had some coliform bacteria on them, and 8% had e. Coli on them. The good news is, is that these authors report a >99.9% reduction in bacteria after washing the reusable bags (3).
Another article of note concerns a "point-source" norovirus outbreak on a soccer team (4). After interviewing, constructing a graph of exposures, and calculating risks associated with different exposures for those who were sick and those who were not sick, it was determined that the likely cause of the norvirus outbreak among this team was a reusable grocery bag containing sealed snacks which were stored in the bathroom of the original team member who was sick. As the authors point out, this exposes one good reason not to store food, or bags containing food, in the bathroom and the need to disinfect bathroom surfaces-- especially after someone has a stomach and intestinal bug. However, they also point out that this, "illustrates one of the less obvious hazards of reusable grocery bags" (4).
I like reusable grocery bags for multiple reasons--they're often easier to carry, they're less likely to break, and they're less wasteful. However, it now seems obviously important to me to wash these bags frequently and to practice good segregation by not putting meat in the bag one day and fresh produce in it the same bag the next day.
I'm curious though, have you ever thought about the importance of washing your reusable bags?
(1) Larson, L. E. coli Infections Spike After Plastic Bag Ban in California. Food Poisoning Bulletin. February 10, 2013.http://foodpoisoningbulletin.com/2013/e-coli-infections-spike-after-plastic-bag-ban-in-california/. Accessed 8/30/13.
(2) Klick, J., and Wright, J. Grocery Bag Bans and Foodborne Illness. August 15, 2012. http://foodpoisoningbulletin.com/wp-content/uploads/Grocery-Bag-Bans-and-Foodborne-Illness-1.pdf. Accessed 8/31/13.
(3) Williams, D., Gerba, C., Maxwell, S., and Sinclair, R. Assessment of the Potential for Cross-contamination of Food Products by Reusable Shopping Bags. Food Protection Trends, (2011) 31(8): 508-513. http://www.foodprotection.org/publications/food-protection-trends/article-archive/2011-08assessment-of-the-potential-for-cross-contamination-of-food-products-by-reusable-shopping-bag/. Accessed 8/30/13.
(4) Repp, K., and Keene, W. A Point-Source Norovirus Outbreak Caused by Exposure to Fomites. J Infect Dis. (2012) 205 (11): 1639-1641. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3415849/. Accessed 8/30/13.