Reusable food shopping bags and packages can contain a high level of bacteria, yeast, mold and coliform counts which pose a significant food safety risk, warns a new study from Sporometrics, an environmental microbiology lab based in Toronto, Canada.
Swab tests of reusable bags last November revealed a bacteria count of 1,800 colony-forming units while 550 were discovered in Tupperware containers. A mould count of 290 was discovered in bags and 10 Tupperware compared with a typical mold count of 150 or less per cubic metre of room air at that time of year.
“The test findings clearly support concerns that reusable grocery bags can become an active microbial habitat and a breeding ground for bacteria, yeast, mold and coliforms.” concluded the study which was funded by the Environment and Plastic Industry Council (EPIC). “This is supported by the high bacterial counts showing that the bag surface (interior) can harbour or breed substantial bacterial populations.”
Food safety fears focus on the risks of cross contamination of food placed in bags contaminated by previous use in successive trips. Also contaminants could be transferred from one bag to another in the check-out packing process.
“The unacceptable presence of coliforms, that is, intestinal bacteria, in some of the bags tested, suggests that forms of E. coli associated with severe disease could be present in small but a significant portion of the bags if sufficient numbers were tested.” according to the report. “Also, it is consistent with everything that is known about Salmonella ecology that it would also be present on rare occasions.”
To combat the threat from food-borne illness associated with re-usable bags and food containers, the study made five specific recommendations. Those included:
- Research. More research is needed to gauge the possibility of microbial build up as reusable bags are reused many times.
- Safety standards. Meat should be double packed in a first-use bag to prevent accidental leakage or drips into the reusable bag. “This should become a mandated safety standard across the entire grocery industry for reusable bags,” say the researchers.
- The investigation of disease outbreaks. Reusable grocery bags and food containers should be added to the list of possible contamination sources when doctors and health officials investigate new food poisoning cases.
- Cleaning packaging. The public should be given full cleaning instructions. All bags should be turned inside out and air dried.
- Reusable protocols. Priority should be given to drafting and disseminating protocols covering the use of reusable food bags and containers. Reusable bags be replaced regularly to avoid the build of harmful bacterial.
Meanwhile, some have questioned the findings of study since it was funded by EPIC which would benefit from the greater use of plastic bags.
“I definitely think that this is their last, final, desperate attempt to scare people off of reusable bags,” said Heather Marshall, spokesperson for the Toronto Environmental Alliance. Neither E. coli nor salmonella, two of the most dangerous food-borne bacteria, were found in any of the bags.
But Cathy Cirko, EPIC vice president Cathy Cirko said: "The (plastic) industry 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."
About 13m cases of food poisoning are reported in Canada each year.