Reusable Bags and Bacteria

Replacing plastic bags with reusable cloth ones are definitely better for the environment but there is a downside. According to a just published Canadian study (funded by the Canadian Plastics Industry Council), bacteria accumulates in reusable grocery bags. However, environmental proponents say the problem can be easily solved by doing two things – washing the bags and not carrying groceries in the same reusable bags used to carry gym clothes or diapers.

The study examined swabs from 28 reusable bags and had the following results:

Sixty-four percent of bags had some level of bacteria.
Of those, six bags had bacterial counts higher than the amount considered
safe for drinking water and three had coliforms and fecal intestinal
bacteria.
Forty percent of the bags had yeast or mold.
The more waterproof the bag, the more likely it is to breed bacteria.

Food safety concerns focused on the risks of cross-contamination of food placed in bags contaminated by previous use in successive trips. Contaminants could also be transferred from one bag to another in the packing process during checkout. The report noted that “the most, dark, and warm interior of a folded reusable bag that has acquired a small amount of moisture is an ideal environment for bacteria.

The problem is similar to the one posed by bacteria on kitchen countertops and cutting boards that can also be transferred to food. Again, washing reusable bags regularly and drying them properly solves the problem. What consumers need to be aware of in drying bags is not to dry reusable bags by laying them out flat. Instead, turn the bags inside out to dry or machine dry bags. Many bags such as those made from canvas can be easily machine washed and dried.

Dr. Richard Summerbell who interpreted the results strongly suggests that cleaning instructions be included when reusable bags are sold and says this in no ways means consumers should stop using reusable bags. At a minimum, bags should be turned inside out and air dried. The approach is one of common sense – wash reusable bags when they are dirty, just as you would your clothing.