To avoid getting sick, carefully wash your reusable bags

The Canadian Plastics Industry Association is getting some media attention today for a microbiological study that it commissioned on the safety of reusable shopping bags.

It turns out that reusable bags can be a breeding ground for potentially scary stuff: bacteria including E. coli and Salmonella, plus mold and yeast.

The researchers noted that using reusable bags as a multi-purpose tote -- something it saw from the majority of bag owners in this study, is a big concern, "particularly if the reusable bags are used to transport gym equipment or diapers. Gym equipment may carry drug-resistant Staphylococcus aureus strains, skin infecting dermatophyte fungi and other dangerous microorganisms."

Among the conclusions: drafting of protocols on the hygienic use of reusables, including suggestions for regular replacement of reusable bags.

My first thought, before reading the entire report, was that consumers can avoid all the hazards of reusable bags (often made of nonwoven polypropylene or other polymers) by simply washing their bags regularly. But the study notes:

Reusable bags can in principle be cleaned, but drying them out thoroughly is problematical and their flimsy nature deters scrubbing that would remove organic deposits. Any imperfect cleaning would tend to add water to incompletely removed food material and thus inadvertently boost microbial growth.

Serious consideration needs to be given to a microbiologically adequate cleaning protocol for such bags. At very least, if people do choose to wash their bags, it is critical that they not lay them flat to dry but instead turn them inside out and suspend them in order to properly air them out. This will avoid the creation of a moist habitat for bacteria, mold and yeast. Consideration should also be given to replacing the reusables regularly to avoid the whole issue of bacterial build up.

Some critics may dismiss the results of this study because it was commissioned by CPIA, which you might assume could be trying to cast doubt on the safety of reusable bags in order to slow the avalanche of taxes and bans on plastic shopping bags.

But the trade group notes that it "strongly supports reduction and reuse, and recognizes use of reusables as good environmental practice, but it does not want to see these initiatives inadvertently compromise public health and safety."

So there you have it. Go ahead and use reusable bags to tote your groceries. But don't use the same bags for food that you use to carry your gym clothes or dirty diapers.

And, for goodness sake, wash them once in a while, dry them carefully, and don't continue to use them to carry food after they get dirty and gross.