With the Marlies’ (Toronto’s most successful hockey team) season over, many Torontonians (they live in Canada) may turn their attention to the frothy battles between Mayor Rob Ford and his city council colleagues. At least until the Leafs start training camp.
Last week, in an attempt to repeal a rule requiring a 5-cent fee for to plastic bags at retail stores, Ford’s focus resulted in Toronto City Council banning plastic bags outright. Irony can be pretty ironic sometimes.
The fallout is following a particularly familiar path: a crusade on reusable bags in the name of public health.
With plastic bags soon to be outlawed in this city, possibly to be followed by other municipalities, many shoppers will turn to reusable bags as the logical replacement.
University of Ottawa microbiologist Dr. Jason Tetro calls them "a nightmare for public health (units)," warning that people should be aware of bacteria growing on their bags.
"if you are getting groceries, then there’s a chance that they will end up leaking into the bag, and then you have growth and virus survival," he said.
He cited a report by the Canadian Plastics Industry Association (CPIA) from 2008, which said that reusable bags can harbour germs from meat and produce.
Nightmare might be a bit of an overstatement. The published evidence doesn’t even show that reusable bags are much of a risk factor.
The CPIA study the Germ Guy cites was based on data generated from swabbing a whopping 25 bags, with 4 controls looking for anything they could find.
Swab-testing of a scientifically-meaningful sample of both single-use and reusable grocery bags found unacceptably high levels of bacterial, yeast, mold and coliform counts in the reusable bags. The swab testing was conducted March 7-April 10th by two independent laboratories. The study found that 64% of the reusable bags were contaminated with some level of bacteria and close to 30% had elevated bacterial counts higher than the 500 CFU/mL considered safe for drinking water.
Um, yeah except that coliform isn’t an indicator of really anything in a shopping bag. It’s a great indicator of water quality, but not great for food (coliforms are all over the place, including on produce). The lack of real data is probably why it was reported in CFU/ml (a water measurement — pretty hard to tell what a ml of a shopping bag represents). The most telling data was that no generic E. coli or Salmonella was found.
Williams and colleagues (2011) have published the only peer-reviewed study on the microbial safety of reusable bags and tested growth of Salmonella in 2 batches. They spiked the bags with 10^6 cfu and let them sit in the trunk of a car for 2 hours. One of the batches, where the temperature reached 47C/117F, showed a one-log increase in the Salmonella. The other batch, where the temperature reached 53C/124F, there was a one-log reduction. That data doesn’t show just a breeding zone – it shows they can be a killing zone too (and I’m not sure how realistic a 10^6 contamination really is).
Friend of barfblog and food safety rock star, Sylvanus Thompson put things into perspective by saying there is currently no campaign targeting reusable bags and that Health Canada’s website provides safety tips for safely reusing grocery bags.
A bigger nightmare is the rumor the Leafs have interest in trading for Roberto Luongo.