Taking the Measure of Plastic Bag Bans

Americans go through 102.1 billion plastic bags each year, and those bags end up everywhere. Whether they’re in whale stomachs, or in our water as microplastics, the volume has people concerned.

In an effort to reduce the amount of plastic, bans on single-use plastic bags are on the rise. California and New York already have state-wide bans, and Maine has just become the third state to do so. In other states, cities like Boston, Seattle and Chicago have their own bans, and more seem likely to follow.

While it’s popular to attack plastic bags, it’s still important to ask questions to make sure the bans are necessary and effective.

Are plastic bags as bad as people think? What are the alternatives, and are they any better? What impact do these bans have on people’s behavior and the environment?

It turns out that when you look at the whole lifecycle of different bags, and the unintended consequences of the bans, the results aren’t straightforward.

Cost of Bag Production

The environmental cost of production is a good starting point in measuring the impact of different bags. Contrary to what you might think, from this perspective, plastic bags win out.

Plastic bags are made by using ethylene. Ethylene   is a by-product of the crude oil refining process and natural gas production.   Manufacturing plants have also gotten very efficient at making plastic, so this process doesn’t generate many greenhouse gases per bag.

Paper bags, on the other hand, require cutting down trees and then processing them in an energy-intensive way. A 2005 Scottish study noted that paper bag production uses about four times as much water as plastic and creates three times the amount of greenhouse gases. It should be noted that in the United States, many paper manufacturing facilities use biofuels and co-gen systems to generate the power used in the manufacturing process which may mitigate some of these emissions.

Even cotton tote bags aren’t better for single use. This is because you need to factor in the land and water used to grow the cotton, as well as the processing and production. One study found that you’d need to use the tote bag at least 131 times to be better than a single-use plastic bag, based on the production impact.

Recycling and Decomposing

One of the biggest problems with plastic bags is what happens after they’re used. This is true whether they’re used once or a couple of times.

While the bags can technically be recycled, municipalities don’t accept them with other recyclables. This puts the burden on the consumer to save them and bring them to a place that will accept them, and most people don’t go to the trouble.

When plastic doesn’t get recycled, it either goes into a landfill or ends up as litter.

In a landfill, plastic takes an average of 500 years to decompose. The volume of these bags in the trash also comes at a cost. California alone spends $25M annually on disposal of plastic waste in landfills.

Paper, on the other hand, decomposes in just two to six weeks. It can also be easily recycled.

Other Impacts of Plastic in the Environment

Additionally, when plastic ends up as litter, the environmental impact is much worse than with paper.

Plastic has become one of the most common kinds of waste products, with much of it ending up in the ocean. A study from UC Santa Barbara found that each year, the world’s oceans receive almost 8 million metric tons of plastic.

As an example of how widespread this is, a recent dive by American explorer Victor Vescovo found a plastic bag at the bottom of the Mariana Trench, seven miles below the surface.

One of the biggest concerns with this is the impact on marine animals. Many are tempted to eat plastic bags, thinking they’re food, but instead the bags block their digestion.  As many as 1 million sea animals die each due to the plastic in the oceans. Among them was a dead sperm whale found in April 2019 with 48 pounds of plastic in its stomach.

A less publicized issue is the fact that plastic bags can cause problems in urban settings by clogging waterways and drains. This was discovered as one of the primary factors in flooding in Bangladesh in 1988 and 1998, which led them to ban plastic bags in 2002.

Microplastics are another concern. These form when the plastic breaks down into smaller and smaller pieces.

No one has enough evidence to show any specific health impacts of microplastics, mostly because it is unethical to ask human test subjects to ingest microplastics due to known health hazards of plastic in general, but the amount and range makes it worth watching. A 2017 study found that 94% of tap water samples from the United States contained microplastics and other studies have found high concentrations of microplastics in fish and shellfish commonly eaten by humans.

Another study also noted that when plastic bags are exposed to sunlight, they begin to give off ethylene, and continue to do so even after the sun sets.  This ethylene can contribute to the creation of atmospheric carbon monoxide, a greenhouse gas.  

.

These factors are what make the plastic bag bans so popular, even though from a production standpoint, they can do less environmental damage than the alternatives.

Considering Consumer Behavior

One issue that policymakers often overlook is how consumers will react to their policies. Production and disposal are only one part of the story. It’s also important to consider if people actually do reuse those bags, for what purpose, and how consumers will change their behavior after a plastic bag ban.

In some cases, people do use the plastic bags again, though often only one other time. The most common examples are to line small trash cans and to pick up after dogs. Those needs don’t disappear with the bans, and those are things you can’t use tote bags for.

As a result, one side effect of the bans is that people buy more trash bags for those purposes. Rebecca Taylor, an economist at the University of Sydney, saw a 120% increase in sales of small, four-gallon trash bags. From an environmental perspective, trash bags are worse than the single-use bags, since trash bags are thicker than grocery bags. This means they use more plastic, and it takes longer for them to degrade.

A quick glance at the comments section of the Portland Press Herald, in an article announcing the ban, revealed that many commenters were “hoarding” their plastic bags in response to the ban, or even buying rolls of plastic bags in advance of the law’s April 2020 effective date.

Additionally, the use of paper bags increases significantly after bans. A survey of a few areas in California found that paper bag usage jumped from 3% to 16%. This meant increased production for paper bags, as well as higher volumes of paper trash.

Still, the bans do encourage people to reuse bags by 40%. The bans also reduce the amount of plastic that ends up as trash, which is the other piece to consider.

Conclusion – It’s Complicated

Economists are notorious for responding “it depends” when asked a question comparing two alternatives.  The impact of bans on plastic bags is no different.  Depending on what you measure, you can find support for using plastic bags, and support for banning them.   

It’s important to remember that the impact doesn’t stop with the manufacturing. It continues with how the bags are used, and what happens with them when they’re no longer in use. It’s also important to recognize that no law is ever passed in a vacuum. We need to consider how people will respond, what alternatives are available to them, and what the unintended consequences may be.   

References:

• http://www.allaboutbags.ca/papervplastic.html
• https://www.thebalancesmb.com/plastic-recycling-facts-and-figures-2877886
• https://www.economist.com/international/2018/03/03/the-known-unknowns-of-plastic-pollution
• https://www.npr.org/sections/money/2019/04/09/711181385/are-plastic-bag-bans-garbage
• http://energycenter.org/sites/default/files/Plastic-Bag-Ban-Web-Version-10-22-13-CK.pdf
• https://www.bbc.com/news/science-environment-48230157
• https://www.abc.net.au/science/features/bags/
• https://www.nytimes.com/2019/04/18/science/what-are-microplastics.html