Paper or Plastic? Reusable or Cotton? Which Shopping Bags are Better for the Environment?

Photo by Evie Calder on Unsplash

I've killed a few reusable grocery bags in the last few weeks. Not intentionally of course, it was accidental. I was hauling them along and one of them got caught on a sharp edge of something or other and... boom... there's a tear in it now. It's still good... for a while but... at some point it will fail entirely. On another one, the seam has gone. A third one has a handle that is coming undone from the stitching. The last two I could theoretically fix if we had a sewing machine... but we don't... so I'm not sure what will become of them. Save them until I can visit someone with a sewing machine maybe...

But, this mass mortality of reusable grocery bags annoyed me. Don't these things need to last for more than a few dozen uses before they fall apart?? If we're really trying to help the environment by ditching plastic bags, don't we have to use the typical fold-up reusable grocery bag 100 times or more? Some of these dying bags are only a year old!

I decided to do some digging... and what I found is fascinating and insanely complicated. In terms of environmental impact, you've got two basic factors to consider: (1) what goes into making and transporting the bag and (2) what happens to the bag after it dies. So some bags have really bag environmental impacts at the front end (e.g. paper bags) but have really good back end environmental impacts (e.g. paper bags). Sooo... are paper bags good or bad? It's complicated.

There have been a number of studies (Denmark and UK) that measure the environmental impact of different types of grocery bag options. I'm going to synthesize that information here.

1. Virgin Plastic Bag
This is the standard against which all other bags are measured, because these virgin bags are the ones we are trying to get rid of. Plastic bags are made from petroleum products (bad) but they are light weight and easy to transport (good) and they can be recycled (good) but if they aren't recycled (and only 5% are recycled), plastic bags can blow around and end up in waterways (e.g. rivers, lakes oceans) where they either break down into micro-plastics (very bad) and/or end up in the stomachs of whales and dolphins and turtles (very bad). If they are landfilled, they last a very, very, very long time (bad).

You'll see that the numbers below vary widely. It is, as I mentioned above, a complicated issue. It depends on whether we are just looking at climate change impacts or whether we are considering the entire environmental impact of a bag from creation until destruction. Most of the studies also use a baseline virgin plastic bag that has been used twice - once to go grocery shopping and once as a garbage bag. If a plastic bag is only used once and then ends up in the ditch... that is a whole other kettle of fish. Sooo... These numbers need to be taken with a grain of salt, but they all trend in roughly the same direction and some of them might just surprise you.

2. Recycled Plastic Bag - Use 2 to 4 times
A recycled plastic bag can have various percentages of recycled plastic and this is obviously better than a virgin plastic bag. But, if you use it to haul your groceries and then use it to bring library books back to the library and then use it to take pop cans to the recycling depot and then use it for some garbage in your car, you're having less of an environmental impact than using a virgin plastic bag. 

3. Paper Bag - Use 4 to 43 times

If you are diligent about recycling your plastic bags, then a paper bag would need to be used 43 times before it's environmental impact is less than your plastic bags. If the plastic bags are not recycled, then paper bags only need to be reused 4 times to beat plastic's environmental impact. These numbers can also be influenced by the amount of recycled content in the paper bag. Like I said, it's complicated!

But using a paper bag 4 to 43 times seems a big ridiculous. Paper bags are not that sturdy and I don't know that I'd be able to even eke out four grocery store runs out of one paper bag. I'm not even sure I could make a paper bag last that long at home. Our Fresh Prep meals come in medium-sized paper bags and I save those and then use them for picking mushrooms, at which point they are pretty much toast and that's only two uses... I suppose paper bags from some high-end store (like The Bay?) could be reused for gift bags... but then what?

So paper bags are not really a solution in my mind. The look and sound eco-friendly, but they really don't seem to be... particularly when you think about the forests that are being cut down to make a bag that will only be used twice and then discarded. Although paper bags made from recycled content are obviously better...

4. Typical Fold-up Reusable Bag (NWPP)- Use 6 to 52 times

Right then, this is the number I'm looking for! These are the reusable bags made from non-woven polypropylene (NWPP) and are sometimes called "Bag for Life". These are the bags that kind of look and feel like fabric but can stand up on their own with a bit  of help. They usually fold into a nice, neat rectangle and sometimes have a plastic insert in the bottom.

These are not the same as the old Superstore (Loblaws) bags which look and feel like fabric and are quite floppy. Those bags are apparently made from PET plastic (recycled pop bottles) and need to be used anywhere from 8 to 84 times.

Then there are woven polypropylene bags which I like to call tarp bags, because they kind of look like they are made from plastic tarp material. They need to be used 5 to 45 times to have a lower environmental impact than a virgin plastic bag.

There are soooo many different options out there. But for our purposes, the only comparisons I could find were to the typical non-wove PP bag. So these need to be used anywhere from 6 to 52 times before they are better (environmentally) than a virgin plastic bag.

Well, that makes me feel slightly better. Because if I use them every week to go grocery shopping then, after a year of weekly use, I've come out ahead in the environmental department! It's just... there are some of these bags that I don't use all that often. Like the non-woven PP bag from the funeral home that handled my Dad's cremation. It's a black bag with the name of the funeral home on it. They gave it to me to carry my Dad's box of ashes but... it seems kind of macabre to use it for grocery shopping. Not to mention it's smaller than a typical grocery bag. Hmmm...

5. Cotton Tote Bag - Use 7100 to 20,000 times

I don't know about you, but this surprised the heck out of me! You'd think that cotton bags would be far better than any of the other options but... no. A lot of it has to do with the environmental impact of growing cotton (water use, fertilizer, pesticides, etc) and then processing the cotton into fabric which then needs to get sewed and shipped, etc.

And... organic cotton is actually worse than regular cotton! That's where the 20,000 times comes in... So, while "organic cotton" might sound like it's good for the environment (no pesticides or fertilizer), it's actually far, far worse (mostly due to lower crop yields).

You'd have to use a regular cotton bag every week for almost 12 years (7100 times) to come out ahead against a virgin plastic bag. And an organic cotton bag would need to be used every week for more than 32 years...

Chart showing Life Cycle Assessment of grocery bags (from EuroNews site)

Conclusion

Of course, you'll find that the plastics industry will be touting the environmental benefits of the thin and filmy plastic bag. They will argue that human behaviour is key and that if people would just recycle their plastic bags, then that would be far better than any of the other options. Which might be true "IF" plastic bags were actually recycled. But given their flimsy, fly away nature, even if they end up at a recycling facility, some invariable blow away or get caught in machinery. I know that in our city, plastic bags can NOT go in the blue bin but need to be bagged up and dropped off at the recycling depot. Or taken back to the grocery store from whence they came. And how many people are going to do that?

So, what's a regular person to do? As it turns out, what really matters is human behaviour. All of the studies and articles gave several key recommendations:

1. Whatever bags you already have (plastic, paper, reusable, cotton), keep reusing them (for all sorts of things) until they fall apart, and then use them to bag up your garbage (or compost in the case of paper bags). Single-use anything is bad...

This was actually a helpful tidbit for me because I've been wondering what to do with the falling apart bags... should I be recycling them or not? But it would appear that none of the reusable bags are currently recyclable in Canada. sigh.

Obviously, I would still try to repair the damaged ones. I'm thinking a piece of Gorilla tape might help the one that has the puncture/tear in it. The ones with burst seams, I'll save until I can visit my sister again and we can sew them back together.

2. Do not buy new bags.

There are an overabundance of reusable bags already out there. And for goodness sake, do NOT buy organic cotton bags... or even just regular cotton bags. They are the worst. Check out your local thrift store and you'll likely find all sorts of bags waiting to be adopted.

Maybe even try making your own. I was already wondering what to do with my old, dying t-shirts. Turns out, they can be repurposed into tote bags as well (no sewing required)! That'll be in an upcoming blog post... and I really like the idea of being able to reuse something like an old t-shirt... Not a still wearable t-shirt. That would be just silly...

3. Wash your reusable bags on a regular (weekly) basis. Particularly if you buy meat. 

You don't want bacteria growing on your plastic bags... or viruses... particularly in the age of Covid-19.

British Columbia is going to introduce a single-use plastics ban this year, which will include single-use plastic bags. But... do you see the loop hole in there? Yup... plastic producers see it too. In some jurisdictions, all they've done is produce thicker plastic bags which are theoretically "multi-use" and... voila... they do an end run around the legislation. Time will tell how this plays out in B.C.

Sources

National Geographic - Sustainable Shopping—Which Bag Is Best?

The Atlantic - Are Tote Bags Really Good for the Environment?

Quartz - Your cotton tote is pretty much the worst replacement for a plastic bag

The Conversation - Here’s how many times you actually need to reuse your shopping bags

Columbia University -  Plastic, Paper or Cotton: Which Shopping Bag is Best?

Danish study (opens as pdf) - Lifecycle Assessment of Grocery Carrier Bags (2018)

UK study (opens as pdf) - Life cycle assessment of supermarket carrier bags (2006)

The Conversation - Here’s how many times you actually need to reuse your shopping bags