In an ideal world, we should be able to identify things we can use with no environmental downside. We don’t live in such a world. Take grocery shopping bags, for example. Plastic bags remain forever in the environment and jeopardize wildlife. Reusable cloth grocery bags are not a perfect alternative.

Industries respond predictably to threats. They often attack their critics and certainly present reasons why their product is better than the challengers. So it’s no surprise that the plastic bag industry feels threatened by the specter of bag bans and the rising popularity of reusable cloth grocery bags. 

And it’s a mistake to dismiss its claims without studying them. They have their own negative environmental impacts. It takes careful study of reusable bags vs plastic bags to find the most eco-friendly choices. 

Some problems with reusable cloth grocery bags

Here is part of the plastic bag industry’s take on reusable cloth grocery bags:

Cloth bags are made overseas and imported from Asia. Too many imported fabric products are made in sweatshop conditions, which raises human rights issues. Importing them probably means greenhouse gas-spewing air transportation to get them to the US or Europe. 

True enough.

If it takes forever and a day for plastic bags to decompose, leftover bits of food in cloth bags decompose very quickly. Therefore, cloth bags are full of germs. Pity the poor bagger who must deal with the stench rising from some shopper’s collection of cloth bags. 

Give me a break!

Just toss reusable cloth grocery bags in the washing machine from time to time. An old survey claimed that 97% of users don’t launder their bags. But I’ll bet anyone will wash something that stinks.

During the pandemic, the plastics industry trotted that old canard to put some grocery chains up to forbidding customers to take reusable cloth bags into their stores as protection against COVID-19. Fearmongering about the coronavirus spawned a number of environmentally disastrous practices. 

In fact, the CDC never identified any cases of contracting the virus from touching surfaces. And it lasts longer on plastic than on cloth or paper. Using basic hygiene practices protects against any legitimate safety issues with cloth bags.

And yet the plastics industry does have one valid objection we should know about: 

The most serious environmental issue with cloth shopping bags comes from the amount of energy necessary to make them. Manufacturing one cloth bag has a much larger carbon footprint than manufacturing one plastic bag. Reusable bags need to be used many times just to break even. Cotton bags use the most energy of all. This point needs more careful explanation.

The environmental footprint of manufacturing shopping bags

Various kinds of shopping bags

Plastic bags are made from polyethylene: high-density polyethylene, low-density polyethylene, or linear low-density polyethylene. The three kinds differ in tensile strength and crystalline structure.

Manufacture of polyethylene uses petroleum as a key ingredient. Energy to run the plant most likely runs on coal, natural gas, or more oil. Oil extraction and the manufacturing process both contribute to air pollution. 

Manufacturers of plastic bags send them to distribution centers, which send them to stores––directly or indirectly. It takes fuel to get them from one place to another. It is estimated that it requires the same amount of fuel to make 12 bags as to move a car one mile. Some stores may be near the distribution centers. Others might be hundreds of miles away. 

Reusable bags come from many different materials. Some are made from heavier polyethylene, which means they’ll last longer before they become unusable. Some are made from polyester, a plastic cloth. Polyester bags last longer than heavy plastic bags, but not as long as cotton. 

Growing cotton requires a lot of energy. water, fertilizer, herbicides, and pesticides. In areas with inadequate rainfall, the water comes from irrigation. Organic cotton doesn’t use synthetic chemicals, but organic pesticides are still toxic. Plus it takes more land to grow the same amount of cotton. 

I have not seen any comparisons of different kinds of reusable cloth grocery bags from such fabrics as bamboo, hemp, or jute. The soft bamboo fabric we appreciate so much for clothing and bedding is bamboo rayon. There’s no point in using it to make shopping bags. The more eco-friendly bamboo linen would make more sense. 

Any of those three fabrics require less water, fertilizer, and pesticides to grow than cotton. So any of them would have a smaller environmental footprint and provide equally sturdy bags. 

Life cycle assessments

A Danish study

I never want to be cynical, but a major study by Denmark’s Ministry of Environment and Food looks more like plastic industry propaganda than a government study. It purports to compare the environmental impact of different kinds of bags from production to use and disposal.

Now, I have never been to Denmark and have never seen the grocery bags their stores offer. That said, the study defines the standard grocery shopping bag (low density polyethylene) as having an average volume of 22 liters (almost 6 gallons) and holding an average of 12 kilograms (a little over 26 pounds). This Danish bag, then is considerably larger than the standard American grocery bag.

The study’s long list of environmental impacts of disposing of the various bags does not include danger to marine life or the intake of microplastics into the food chain. The authors also considered the effects of littering negligible in Denmark! 

The study concludes that an organic cotton bag must be reused 20,000 before disposal to make up for the extra environmental cost of making it. That is, it says making and disposing of 20,000 standard polyethylene bags have the same environmental impact of one organic cotton bag! 

British studies

A British study used high-density polyethylene bags as its baseline. It concluded that one plastic bag reused once has the same global warming potential as one paper bag used four times or one cotton bag being used 171 times. That’s considerably more than the footprint of polyester bags or heavier reusable plastic bags. Most paper bags are only used once. For some reason, the study assumed that cotton bags are used only 51 times before being discarded.

I have seen other estimates based on British research that suggest a higher number than 171, but they’re all in the hundreds, nowhere near 20,000.

All this research provides cover for the idea that single-use plastic bags are better for the environment than cotton bags.

The trouble with life cycle assessments

While the Danish study looks like propaganda from the plastics industry, it is an example of a Life Cycle Assessment (LCA), which studies the environmental impact of products from manufacture to disposal. LCAs result from careful scientific study of a dizzying about of data. They may appear in multiple refereed journals, but by the time the public gets to look at them, it is difficult or impossible to discern all the assumptions and simplifications behind them. 

Different LCAs of the same kinds of products can result in vastly different conclusions. So in this case, two studies differ in two orders of magnitude when it comes to the environmental impact of reusable grocery bags.

What looks easy to interpret requires an expert to determine how the scientists made their calculations. At best, LCAs don’t account for anything difficult to measure, such as microplastics or how much ingesting plastic contributes to the death of a sea creature.

They have, in other words, become so generalized that the public should take them more as a rule of thumb than a definitive guideline. 

The environmental footprint of disposing of bags

Disposable plastic bags

Plastic bags do have one big environmental advantage. Bag for bag, producing them carries the lowest carbon footprint. Although they’re made of polyethylene, manufacturing them produces less waste, carbon emissions, and harmful byproducts than other bags. 

Thin as they are, it is possible to reuse them. Thrift stores would welcome whatever you can give them. At the very least, plastic bags can serve as wastebasket liners after you get them home and empty them. Or you can use them to pick up pet waste. 

The problem with plastic bags comes from disposing of them. 

Recycling plastic shopping bags

As for recycling, you can’t put plastic bags out at the curb or in anything that’s bound for a materials recovery facility. They will tangle equipment there. The facility can do nothing with them except pay to send them to the landfill.

To recycle plastic bags, you can take them back to a grocery store and put them in the plastic receptacle there.

For some reason, lots of people seem to think that’s too inconvenient, so plastic bags get recycled at a lower rate than other materials. That’s really too bad, because plastic bag recycling provides the raw material for really useful products, especially composite lumber. 

Not recycling plastic shopping bags

We are a nation—or perhaps a species—of litterbugs. When you take a walk, you regularly see plastic bags and other litter on your way. There’s even more of it along the highways. 

To add insult to injury, the pandemic also caused state highway crews to pick it up less frequently. So people complained. I wonder how many people think nothing of tossing litter out their car windows but then get upset by all the litter they notice.

When people toss plastic bags out of a moving vehicle, the wind carries them upward. They’ll either come back to earth or get caught in tree branches. If no one picks them up off the ground, they’ll eventually get into waterways. At best, they’ll get into sewers, where wastewater treatment plants can retrieve them. At worst, they’ll get into a stream and, eventually, an ocean. 

When natural products degrade, they turn chemically into something else. Our dirt is basically what happens to leaves, twigs, organic garbage, etc. after insects, fungi, bacteria, and worms have ingested and excreted it. 

Plastic only breaks down into smaller and smaller pieces. It doesn’t become something else. 

We are only beginning to recognize the problem of microplastics. By now, you have them in your body. They’re in the food you eat. You may know of plastic in seafood. Less well known, it’s in fruits, vegetables, and even drinking water. 

The end of life for reusable bags

Nothing lasts forever. Your reusable cloth grocery bags will wear out eventually. Disposal options include landfilling or incineration for any of them. You can compost cotton bags, but not polyester. Heavy-duty reusable plastic bags present most of the same end of life problems as disposable bags, except they’re less likely to wind up on the side of the road as litter.

Paper bags are easier to recycle than plastic bags. They’re also biodegradable and compostable. But it takes about four times as much energy to make a paper bag as a plastic bag. Since paper bags are the least durable packaging option, it would be difficult to reuse them enough to neutralize the greater environmental impact of making them.

Recycling paper results in shorter and weaker fibers. Recycling recycled paper shortens them still more. So it can go through the recycling process only a few times before it becomes useless. 

I wonder why the British study assumed that people use cotton bags only 51 times. The only reason I can think of to discard them is when they wear out. I have a heavy cotton bag with three holes in the bottom that it got from someone habitually dragging it on the ground when it was full. I have used it in that condition for more than 15 years. The holes haven’t gotten any bigger.

I haven’t kept track of how many times I’ve used it, but it’s probably more than 171. And since it’s as big as two plastic bags, it would take only 85 uses to pay for its manufacturing footprint.

The environmental impact of bag bans

Some jurisdictions have enacted plastic bag bans. Some retail chains have voluntarily stopped offering plastic bags. Delivery services have likewise discontinued them. This development started sometime later than publication of the British study.

Shoppers no longer accumulate cheap, disposable plastic bags. They receive more reusable bags than they know what to do with. 

How does that happen? 

First, if stores and delivery services cannot issue cheap plastic bags, they must issue something more expensive instead, heavier plastic or polyester (and polyester bags are plastic). Stores often sell these alternative bags rather than giving them away. 

Second, many consumers store their reusable bags at home and forget to take them to the store. So they have to buy more bags there. Other consumers rely on grocery delivery services, which could use paper bags but often deliver polyester bags instead. Some charities regularly send polyester in mass mailings. 

After a while, a glut of reusable bags overwhelms their cupboard space. One Canadian college student posted that she and two roommates had discarded 175 of them, with more coming all the time. The discards probably went to the landfill. 

I have a simple solution to forgetting to take bags to the store: don’t store them at home; leave them in the car. If you get into the store without them, you need only walk out to the parking lot. You won’t need to buy more bags that way. Unfortunately, that suggestion doesn’t help people who don’t drive or eliminate the extra bags that come from delivery services.

Governments could impose some kind of extended producer responsibility, or at least require stores to take back bags, wash them, and resell them. I won’t hold my breath. 

Predictably, some progressives suspect that stores don’t want to participate in any kind of instore-circular bag program because it would cut into the profits of selling new bags! That’s plain foolish. Probably no store profits from bag sales. 

The bottom line

Comparisons of the environmental costs of making a single standard plastic grocery bag vs a single bag of some other materials often seem to imply that they’re all about the same size and capacity. 

My current collection of reusable cloth shopping bags has several different sizes. Some are about the same size as the standard plastic grocery bag. Some hold much more. The largest could easily accommodate the contents of four or five plastic grocery bags. And, of course, they go with me into more than grocery stores.

To the best of my recollection, the first time I ever received plastic instead of paper, it took at least three plastic bags to hold what would have fit into one paper bag. Of course, with the handles, I could carry  half a dozen plastic bags more easily than one paper bag. And when I bought a lot of groceries, the paper bags were often double bagged, because I didn’t have a car and couldn’t carry more than one bag back home. 

But disposing of trillions of plastic bags eliminates the environmental advantages in manufacturing them. The only thing worse is routinely discarding any kind of cloth bag after a single use.

Someday, perhaps, bags from some compostable bioplastic will drive polyethylene from the market. Someday, perhaps, bags made of bamboo, jute, or hemp will drive cotton from the market. At least they’ll likely find a place in it sooner rather than later. 

Until then, existing reusable cloth grocery bags remain the most environmentally friendly shopping bags. But only if you use them many times for many years and wash them regularly. And cotton beats polyester, which is not recyclable or biodegradable.

Sources:

Are reusable bags really better for the environment? / Kati Sakurra, Nature Code. May 2, 2020 
Here’s how many times you need to reuse your reusable grocery bags / Katie Hunt, CNN. March 13, 2023 
Life Cycle Assessment of grocery carrier bags / Ministry of Environment and Food of Denmark. February 2018 
Plastic fantastic! Carrier bags ‘not eco-villains after all’ / Marvin Hickman, Independent. February 20, 2011 
Sustainable shopping—which bag is best? / National Geographic Resource Library. July 10,  2020 
We’re drowning in reusable bags. Are bag profits preventing big grocers from adopting solutions? / Sophia Harris, CBC [Canadian Broadcasting Company] News. October 4, 2024 
Where do plastic bags go? / Shannon Bond, The EPA Blog. March 6, 2014