Rebecca Taylor
Although plastic carry bags are widely referred to as “single-use,” consumers don’t necessarily treat them that way. By comparing the reduction in plastic carry bags used at checkout to the increase in trash bags sold, my results revealed that 12 to 22 percent of plastic carry bags were reused in California as trash bags pre-ban. Each reuse avoided the manufacture and purchase of another plastic bag.Who were the people who reused plastic carry bags pre-ban, and presumably bore the burden of buying trash bags post-ban? I found that bag reuse was higher for people who purchased pet items and baby items “ in other words, who needed to collect and dispose of excrement. In 2017, nearly 6 percent of U.S. households had a child under 5 years old, 44 percent owned a dog, and 35 percent owned a cat.Why didn’t policymakers foresee that bag bans could drive up trash bag sales? Policies typically miss the mark because policymakers either do not understand people’s current behavior or fail to anticipate how people will respond in a completely new situation.
Governments are increasingly banning the use of plastic products, such as carry bags, straws, utensils and microbeads.
The goal is to reduce the amount of plastic going into landfills and waterways. And the logic is that banning something should make it less abundant.
However, this logic falls short if people actually reuse those items instead of buying new ones. For example, so-called ‘single-use’ plastic carry bags can have a multitude of unseen second lives “ as trash bin liners, dog poop bags and storage receptacles.
A UK study calculated that a shopper would need to reuse a cotton carry bag 131 times to reduce its global warming potential below that of plastic bags used once to carry newly purchased goods. To have less impact on the climate than plastic carry bags also reused as trash bags, consumers would need to use the cotton bag 327 times.
In a recent study, I examined how plastic bag bans in California have changed the types of bags people use at checkout and results showed that bag bans may not reduce total plastic usage if people begin purchasing trash bags to replace the carry bags they were previously reusing for garbage. As this finding shows, well-intended bans can have unintended consequences.
From 2007-2015, 139 California cities implemented plastic bag bans. This led to the first statewide plastic bag ban in the US, voted into law in 2016. Because these restrictions were adopted at different times across the state, I was able to compare bag usage at stores with bans to those without.
Using data from retail outlets, I found that bag bans in California reduced plastic bag usage by 40 million pounds/year, but this reduction was offset by a 12 million pound annual increase in trash bag sales. This meant that 30% of the plastic eliminated by the ban was coming back in the form of trash bags, which are thicker than typical plastic bags. In particular, my results showed that bag bans caused sales of trash bags to increase.
Moreover, my study underestimated reuse because it did not examine other ways in which people use plastic carry bags, such as wrapping fragile items for shipping or storage instead of using plastic bubble wrap. Nor did it address increased use of reusable bags made of thicker plastic in place of disposable plastic bags.
The UK study examined the impact of shifting to thicker reusable plastic bags and found that if these thicker bags were not reused between 9-26 times, they would have a higher global warming potential than disposable plastic bags reused as trash bags.
I also found that plastic bag reuse was higher among people who shopped for bargains. Although reusing shopping bags as trash bags could be motivated by environmental concern, it also could be motivated by frugality. Interestingly, I did not find a correlation between plastic bag reuse and income or political leaning, but I did find a positive correlation with higher levels of education.
Banning carry bags illustrates the first problem. Before plastic bags were banned, there was little data on who reused plastic bags or how they reused them. California’s natural experiment revealed this information for other jurisdictions to improve upon.
In my view, policymakers who want to minimize plastic use should consider ways to help people reuse disposable bags. One option would be to offer incentives for producing inexpensive, thin carry bags specifically designed and marketed to be used first as carry bags, then for trash. Such bags would need to sell for less than 9 cents per bag to be competitive with trash bags. Ideally, they would be thin enough to contribute no more to climate change than traditional carry bags.
Another route that some jurisdictions, including Washington have implemented is adopting fees instead of bans, which allows customers to continue using plastic bags as trash bags for a small fee. This is seen to be effective in encouraging consumers to switch to reusable bags.
However, current bag fees have not promoted other uses for disposable carry bags. These policies could be improved by educating customers about the environmental benefits of reusing disposable products. As a general rule, the more an object can be reused “ even a disposable item “ the better for the environment.
