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How sustainable is your reusable bag? Depends on how much you reuse it

Reusable bags are often touted as an eco-friendly solution to single-use plastic bags. But how many times do they need to be used to actually equal or improve upon the environmental impact of their predecessor?
A reusable bag has a varying environmental impact based upon what it's made of; factors such as the emissions produced during its production and disposal matter.

Reusable bags are often touted as a choice made with the planet in mind.

Frequently spotted with bunches of kale teeming out of them and in mass numbers at the farmers market, they exist in an aesthetic that also includes recycling and eating less meat — other planet-friendly actions.

These bags are also frequently dotted with slogans such as “Save Mother Earth” or “Be a conscious consumer.”

But how fruitful can this reusable bag campaign really be?

According to Shelie Miller, Program in the Environment director at the University of Michigan, it all comes down to a game of ‘whack-a-mole.’

“The big idea is to make sure we don't play environmental whack-a-mole,” Miller said. 

“Where we are basically trying to solve one problem with a well-intentioned solution that ends up creating a new and different problem, or making a different environmental problem worse.”

In this game of whack-a-mole, those well-intentioned solutions come in the form of reusable bags — cotton, paper or fabric.

While that new tote bag may be trendy or aesthetically pleasing, the user of that bag actually needs to put in a significant amount of effort, Miller says, to make it count towards a climate solution and not a new problematic mole.

“For the most part, reusable bags are better for the environment,” Miller says. “But they actually do need to be reused a large number of times in order to actually receive environmental benefits.”

Reusable bags have this requirement for a minimum number of uses because of the materials they’re made of, she said.

“To make up for that additional material that comes in your reusable bag, you actually have to reuse it a bunch of times in order to make up for the single-use plastics, which tend to be very thin film and very low material intensity,” she said.

The United Nations Environment Programme published a report in 2020 compiling data from seven life cycle assessments of reusable bags completed over approximately the past decade. 

The report found a cotton bag needs to be reused 50 to 150 times to have less impact on the climate than one single-use plastic bag (SUPB) and a thick, non-woven polypropylene bag — often found hanging around at the end of grocery store checkouts — has to be reused 10 to 20 times.

In Vancouver, shopping bag bylaws state that a reusable bag must be capable of at least 100 uses and made primarily of fabric, such as cotton, canvas, polypropylene or polyester.

Paper bags, the study notes, have a smaller impact than SUPBs when it comes to littering. But Miller and the UN note another trade-off in choosing paper over plastic that involves the negative eutrophication and acidification impacts of paper bags.

“Often the single-use plastic bag, from a climate perspective anyway, actually has fewer environmental impacts than the paper bag,” she said. 

“But again, you do have potential marine issue problems with improperly disposed of [plastic] bags. So there's a trade-off there.”

Currently, paper bags sold in Vancouver must be made of 40 per cent recycled content and cost shoppers 15 cents. This fee will increase to 25 cents in 2023.

What goes into a reusable bag’s footprint?

To determine how many uses each type of reusable bag needs to neutralize its environmental impact, several factors need to be considered. 

From what resources it requires in production to how easily it can be plucked from a garbage can by a light breeze — all of these characteristics matter.

For starters, the weight of a shopping bag plays a pretty big role in determining its impact, according to the UN report. If two bags are made of the same material but one is double the weight, the heavier bag will also have double the impact. 

For SUPBs, their weight varies internationally. In the United States, an SUPB weighs around six grams while in the United Kingdom it weighs around 18 to 20 grams.

To equal out the impact of the two bags, the heavier one would have to be reused more often or used to carry more goods.

The technology and type of energy used to produce these bags is also something to consider, according to the UN report. Paper bags are a great example of this as their climate impact varies greatly depending upon the energy source that’s fuelling the pulp and paper production. 

And once it has lived out its usefulness, a bag’s end of life plays a huge role in its environmental impact. 

When possible, recycling is always a good option, the UN report states.

“Recycling of bags in state-of-the-art facilities reduces the impacts in the end-of-life phase and always reduces the use of raw materials for producing new bags,” the report states.

This compares to a landfill, where the UN report found a paper bag can release harmful methane emissions while a plastic bag can remain relatively inert. 

Incineration is another variable in the disposal of a bag. If a SUPB is incinerated its emissions will affect the climate much more than the emissions from the incineration of a paper bag, which would just enter into the natural carbon cycle.

One final consideration, Miller notes, is whether or not a SUPB has another use before it’s disposed of.

Using SUPBs for dog waste or as a trash bin liner changes a single-use bag to a double-use bag, which according to Miller, complicates the whole assessment. 

“It changes the math a little bit, but it doesn't change the overall outcome that reusables do tend to be better,” Miller said. “You just have to reuse them a large number of times.”



How effective are plastic bag bans?

In September 2020, Tofino, Ucluelet, Saanich, Richmond and Victoria were among the first municipalities in B.C. to have bylaws banning single-use plastics approved.

Now, over 30 other communities in B.C. are either implementing, planning to implement or considering a bylaw related to banning single-use items, according to the Retail Council of Canada. 

A recent Portuguese study found that when a small fee was instituted on lightweight plastic bags, consumption of these bags dropped by a dramatic 99 per cent between 2011 and 2018.

While these results appear strikingly positive, Miller said it’s important to approach plastic bans with a cautious optimism until more evidence is available.

“It’s going to depend a lot on individual cultures. The U.S. is going to behave very different than Europe for lots of different reasons,” Miller said. “We do need a little bit more data to be able to say exactly how customers will react to any sort of bans or intervention.”

Until that data is clearer, Miller said it’s hard to say for sure if these bans will encourage consumers to go the reusable route, reduce their consumption or seek substitutes like paper bags.

This is where consumer behaviour plays a huge role in the success of government policy.

These policies could be very powerful, Miller says, if they actually provoke less consumption. Instead of just a switch to another bag material, such as paper, that then becomes the next ‘whack-a-mole’ issue to arise.

“In the best possible scenario, you have a plastic bag ban or elimination of single-use plastics that actually results in reduced consumption,” she said. “So people just use fewer bags overall.”

But it's the false sense of environmental responsibility that comes from the one-time use of a reusable bag that Miller says consumers need to be conscious of.

“You can't go to the store every time and say, ‘Oh, I forgot my reusable bag so I’ll buy just another reusable bag and another reusable bag,’” Miller said.

“Then we have closets full of reusable bags and we'd be better off with just the single-use alternative.”

This choice to have more sustainable shopping habits is not a one-off decision, Miller emphasizes. It’s a forethought that needs to occur every time shoppers leave home.

“It does require a shift in mentality of saying, ‘All right, this is my bag. I'm not going to get 50 different bags, use each of them a couple of times and then maybe recycle them,’” she said. 

“Because then you're basically… making reusables single-use.”

Beyond the bag

While it can be easy to default to this seemingly simple eco-friendly action, Miller says a person’s impact is much greater than what they carry around at the farmers market.

“Your personal environmental footprint goes way beyond just single-use plastic bags,” she said.

This includes what’s actually being carried by those reusable bags.

“What's in your grocery cart is way more impactful than what you pack those groceries in,” Miller said.

The National Zero Waste Council reported that in 2022, the average Canadian household threw away about $1,300 of food per year.

Within all that food waste, 63 per cent of the food being thrown out could have been eaten, the council reports.

Food packaging is another huge culprit of plastic waste, Miller says. She encourages consumers to buy in bulk when possible to avoid the extra waste.

Personally, Miller does her best to practice what she preaches.

“I have a reusable bag that I bought probably five years ago and one of the straps just snapped on it, and it made me so sad,” she said. “I feel like I have done my part with reusable bags.”

But for those still trying to get the most out of their reusable bags, Miller says the most important thing to remember is to be kind to yourself.

“[Don’t beat] yourself up if you happen to forget your reusable bag,” she said. 

“There are plenty of other things that we can do to reduce our impact, plastic bags are just one very, very, very small fraction of our environmental profile.”