Researchers from the University of Arizona and Loma Linda University conducted a study to assess the potential for cross contamination of food products from reusable bags for carrying groceries in California and Arizona. They discovered that reusable bags are seldom, if ever, washed and often used for multiple purposes. Large numbers of bacteria wee found in almost all bags and coliform in half. E. coli were identified in 12% of the bags and a wide range of entire bacteria, including several opportunistic pathogens. When meat juices were added to bags and stored in the trunks of cars for two hours the number of bacteria increased 10-fold indicating the potential for bacterial growth in the bags. Hand or machine washing was found to reduce the bacteria by greater than 99.9%. The results indicate that reusable bags can play a significant role in the cross contamination of foods if not properly washed on a regular basis. (1)
Professor Charles Gerba, who led the study said, “Our findings suggest a serious threat to public health, especially from bacteria such as E. coli, which were detected in half of the bags sampled.” A poll revealed that 97 percent of shoppers who used eco-friendly bags never washed or bleached them. (2) About a third said they also used their food-shopping bags to haul around non-food items. Gerba says the public needs to be educated about the proper care of reusable bags by printed instructions on the bags or through public service announcements.
Another wrinkle involves the possibility that reusable bags, mostly made in China, could potentially contain unsafe levels of lead. There is minimal concern that the lead would easily rub off on food when the bags are new. However, there is a possibility that as bags wear down, lead could accumulate in landfills, creating a potential environmental hazard. Senator Charles Schumer of New York is seeking a federal investigation of lead in some grocery bags. (3)
- Charles P. Gerba, David Williams and Ryan G. Sinclair, “Assessment of the Potential for Cross Contamination of Food Products by Reusable Shopping Bags,” June 9, 2010
- Harry Wallop, “Bags for life could have E. coli,” Telegraph.co.uk, June 30, 2010
- The Associated Press, “Probe is sought of lead in reusable grocery bags,” November 14, 2010