Paper or plastic? Whether because the individual consumer has adopted a green philosophy or because plastic grocery bags have been banned in the municipality, the response to that question frequently is “neither, I have reusable shopping bags.” This response prompts another question: are those reusable grocery bags enhancing the potential for consumers to become ill with a food-borne illness, including from leafy greens that may become contaminated with E-coli through contact with the bag itself?
Recent studies, articles, and comments by experts appear to confirm this as an issue to which consumers, as well as grocery stores and even farmers markets, should pay more attention. One example is that a research paper published in 2011 by professors at the University of Pennsylvania and George Mason University found that after San Francisco’s ban on plastic shopping bags took effect in 2007, there was a spike in the city’s emergency room visits/treatment for E-coli infections and a 46% increase in deaths from food-borne illnesses in the three months after the ban took effect. Environmentalists and proponents of banning plastic grocery bags altogether criticize this report. However, in a similar context, researchers at the University of Arizona and Loma Linda University School of Public Health examined reusable grocery bags taken from randomly selected individuals in California and Arizona grocery stores, and in a 2011 paper found that E-coli bacteria was identified in 8% of all the reusable bags examined. That report also reflects that half of the individuals interviewed used their bags more than once per week, three-quarters did not ask that meat be separated from fresh produce, and only 3% cleaned their bags on a regular basis which means that 97% admitted they did not clean the bags regularly, or never cleaned them at all.
Even a recent study out of North Carolina State’s Department of Food, Bioprocessing, and Nutrition Sciences and the University of Nottingham’s, United Kingdom, School of Biosciences, which examined the claim that 8% of reusable grocery bags contained E-coli, concedes that there is some potential for contamination although states it is “low.” See “Cross-Contamination Risks in Reusable Grocery Shopping Bags and Potential Risks to Patrons: A Model Applied to Leafy Greens E-coli 0157:H7.” In that study, only 34.69% of the 107 patrons examined “attempted” to clean their reusable bags, with 5% claiming they cleaned the bags on a regular basis. In addition, only 28% of the patrons assessed either separated or specified the type of food product that should be placed in each bag. According to the study, “most patrons expressed hesitation and lacked an explanation of a potential reaction to how they would handle a situation of meat drippings or contamination.”
It is significant that only 3% of participants in one study and 5% in another study stated they cleaned their reusable bags regularly. Professor Thomas Hugh Pennington, emeritus professor of bacteriology at the University of Aberdeen in Scotland who has chaired inquiries into E-coli outbreaks in Wales and Scotland, has cautioned that reusable grocery bags should not be used at all to carry packaged raw meat or vegetables with soil attached because any bacteria from those products can be transferred to other foods later placed in the bag, some of which might be consumed without cooking. Professor Pennington cautions that even washing or using antibacterial sprays is insufficient to kill all of the bacteria that may be transferred to reusable bags (and presumably even plastic bags) by packaged raw meat, the package exterior of which may contain bacteria.
Studies and experts agree that E-coli outbreaks are larger and more frequent than even fifteen years ago. In recent years some of those outbreaks have involved leafy greens, and there is speculation of a link between feedlots or cow pastures, and the contamination of leafy greens with E-coli. According to Dr. Robert Tauxe, Division of Food-borne, Bacterial and Mycotic Diseases at the Centers for Disease Control and Prevention, in general the bacteria that cause food-borne illnesses prefer non-acidic foods, and the factors that the kinds of produce that cause E-coli outbreaks typically have in common is they are grown fairly close to the ground, are not acidic, and are eaten without cooking. This tendency to lack acidity is significant and Dr. Tauxe has commented that even tomatoes and apples are getting sweeter and less acidic, perhaps due to increasing consumer preference for sweetness.
Regardless of whether leafy greens are packaged as salad mixes or simply purchased separately and all outer leaves removed before consumption, carrying both raw meat and leafy greens in the same grocery bags clearly is unacceptable. Reusing that bag is equally unacceptable when the bag has held packaged raw meat or produce with soil attached, the consumer seldom if ever cleans the bag, and the bag is used thereafter for produce that generally is not cooked including whole leafy greens.