What's the germiest surface in a supermarket? You might be surprised

In light of the global COVID-19 pandemic, Canada's biggest grocery store chains have increased their cleaning and disinfecting measures. But how well is that working?

CBC's Marketplace visited 24 grocery stores around Toronto to swab the following high-touch surfaces: shopping cart handle, front of the shopping cart, baby seat, basket handle, freezer door handle and PIN pad.

In total, Marketplace collected more than 130 samples from the country's biggest chains and some of their subsidiaries Walmart, Costco, Sobeys and Freshco, Loblaws and No Frills, Metro and Food Basics.

The samples were then tested by an accredited microbiological laboratory in Mississauga, Ont.

The goal was not to compare the grocery chains but to determine which surfaces in general have the most germs.

As research on COVID-19 evolves, scientists say surfaces are not the main way the novel coronavirus is transmitted. But high-touch surfaces can nonetheless be a way for other types of pathogens to spread.

The lab tested the swabs for the total number of bacteria on each surface, as well as for E. coli, which is often an indication of cleanliness.

Jason Tetro, a microbiology expert, analyzed the swab results.

"The takeaway is this: Grocery stores have implemented new practices to try and improve hygiene, and as we've seen, it's actually doing a good job in one [respect]," he said. "Is there room for improvement? Absolutely."

Germiest surface

The surface with the most bacteria was the PIN pad used during checkout.

"We saw lots of bacteria [there]," said Tetro.

Marketplace producers rarely saw grocery store employees wiping down PIN pads between customers.

Tetro said that when it comes to the PIN pad, there could be room for improved cleaning."It really is something that we need to be taking a closer look at and maybe doing some better disinfection protocols."

The surface with the second-highest bacteria count was the basket handle.

Tied for third place were the freezer door handle and the front of the shopping cart the part you would grab if you were to pull the cart towardyourself.

While some surfaces had more bacteria than others, some microbiologists Marketplace spoke to, including Jeff Farberat the University of Guelph, cautioned that not all bacteria areproblematicand that sometimes a low bacteria count can still be concerning if it contains more dangerous bacteria.

Industry mindful of customer safety

The Retail Council of Canada, which represents all of the supermarkets Marketplace swabbed, said that the grocery industry has worked closely with governments and health agencies across Canada to ensure health, safety and security.

"Designated as essential retailers, grocers led the way on how to operate safely in a retail environment, one that has since been followed by others as they have reopened or revamped operations," a RCCspokesperson said via email.

In a statement, Loblawsaid, "We are confident that our protocols and sanitization efforts have contributed to keeping [customers] safe and well."

WATCH | Here's what we found by testing more than 130 swabs from 24 different grocery stores:

These are the germiest surfaces in your supermarket

4 years ago

Duration 4:25

CBC Marketplace tested more than 130 swabs from across 24 different grocery stores to reveal which surfaces have the most bacteria.

Metro said it's been working closely with Public Health units across Ontario and that its "operations team is in daily contact with our stores to reinforce our operational best practices and safety protocols."

Walmart said via email that it continues to take measures to support the well-being of customers and associates through "regular cleaning of high-touch areas such as checkouts, payment terminal keypads and shopping carts."

Some grocers provided more specific information on their cleaning measures. For example, Costco said that frequently touched surfaces like the debit machine are sanitized every hour, while Sobeys said it has started rolling out PIN pad covers to make the surface easier to clean.

Cleanest surface a surprise to experts

The cleanest surface in grocery stores was the shopping cart handle.

"I'm literally shocked that it's the lowest [bacteria count], because it should be the highest," said Tetro. He has swabbed grocery carts in the past and has found them to have high bacteria counts and traces of E.coli but not this time.

Alexandra Calle, an assistant professor of microbiology at Texas Tech University, has also swabbed shopping cart handles, and was similarly surprised at the low bacterial count found in this test.

What's changed? Tetro and Calle said it seems the enhanced cleaning protocols supermarkets have implemented in this area are working.

The majority of the carts swabbed by Marketplace producers had either just been sprayed and wipedby an employee or were chosen from a row of carts with a sign indicatingthey had recently been sanitized. From what the producerssaw, most shopping carts were regularly cleaned after each use.

"You try to have a benchmark what should we be looking for when it comes to a bacterial number? Well, now we know," Tetrosaid. "We should be doing as good as the shopping cart handle."

Runner-up for the cleanest surface was the baby seat. Tetro suspects this is because the baby seat is likely being sprayed by some of the disinfectant that's aimed at the shopping cart handle.

"That bystander effect is making a baby seat actually safer than anytime I've ever seen it in the past," he said.

Sanitizing solutions

None of the surfaces Marketplace swabbed had E. coli, a fecal coliform often found in the digestive tract.

When E. coli is found on highly touched surfaces, it's an indication that whoever touched the surface last did not properly wash their hands, likely after using the washroom.

For Tetro and other microbiologists Marketplace spoke with, the fact that E. coli wasn't found on any of the surfaces is another sign that cleaning protocols and proper hand-washing or at least applying hand sanitizer when entering a grocery store are working.

"Hand sanitizer, as we all know, is really good at getting rid of E. coli," said Tetro.

Tetro'stips

Despite the increased sanitation measures grocery stores have instituted, Tetro said there are additional steps shoppers can take in order to practise good hygiene.

When paying for your groceries, Tetro recommends using the tap feature where it's available. (In April, Mastercard and Visa raised the tap limit on all credit card transactions from $100 to $250 to facilitate more contactless payments.)

When cleaning surfaces, Tetro said to remember that cleaners and disinfectants need time to work. This is known as contact time, and it varies depending on the sanitization product.

Tetro says a common way germs spread is through our hands.

"You have to realize, you touch your face about 16 times every hour," he said. "You cannot help it, that's just who you are."

He suggestsusing "an alcohol-based hand sanitizer, 62 to 70 percent ethanol or alcohol for 15 seconds of wetness on your hands .... [That's] going to be efficient to keep you safe."