Efforts to reduce plastic waste by banning free grocery bags may have unintended consequences, according to a new study.
Researchers found that while these bans initially encouraged people to cut back on single-use bags, they also led to an increase in the purchase of plastic trash bags, raising questions about the overall environmental impact.
The study, published in the Journal of Marketing Research, analyzed policies in Austin and Dallas, Texas, where bans on single-use plastic bags were introduced and later repealed.
The findings reveal that even after the bans were lifted, some behaviors sparked by the policies persisted—sometimes in ways that didn’t benefit the environment.
Plastic bag sales rise after ban
When cities prohibited stores from giving away free plastic grocery bags, customers began buying more plastic trash bags. Many people had been reusing the free grocery bags as liners for household trash bins. Without those free bags, they turned to store-bought alternatives.
“We were hoping the bans would create positive environmental habits, like using fewer single-use plastics overall,” said Hai Che, an associate professor at UC Riverside and one of the study’s authors. “But the data showed that people ended up buying more plastic instead.”
The team reached this conclusion by analyzing barcode scanner data on consumer purchases. They found a significant rise in trash bag sales during the bans, which continued even after the policies were repealed.
The study examined how behaviors changed in Austin and Dallas, two cities with different policy durations:
- Dallas: A 5-cent fee on plastic bags was in effect for just five months in 2015 before legal challenges forced the city to repeal it. After free bags returned, trash bag sales initially dropped sharply but took over a year to return to pre-policy levels.
- Austin: A full ban on single-use plastic bags lasted five years, from 2013 to 2018, before being overturned by a Texas Supreme Court ruling. Even 18 months after the ban was lifted, trash bag sales remained nearly 39% higher than before the policy.
The researchers noted that the longer a policy is in place, the longer its effects linger after it ends. In Austin, habits like buying trash bags persisted much longer than in Dallas, where the fee was short-lived.
Do the benefits outweigh the costs?
To understand the overall environmental impact, the team conducted a “break-even analysis.” They calculated how many fewer free grocery bags consumers needed to use to offset the rise in trash bag purchases. The results showed that even small reductions in grocery bag use could make the policies environmentally beneficial:
- In Dallas, using one less grocery bag every seven trips would break even.
- In Austin, using one less grocery bag every five trips would balance the increase in trash bag consumption.
“This shows that the policies can still have a positive environmental impact, even when they are repealed,” said Che.
The study highlights the unintended consequences of well-meaning regulations. While it focused on plastic bags, similar effects have been observed in other areas. For instance, taxing sugary drinks has sometimes led to increased purchases of sugary snacks, and energy-saving incentives can occasionally result in higher energy use elsewhere.
“These findings remind us that policies don’t exist in a vacuum,” said Che. “People often respond in ways that policymakers don’t anticipate, and those behaviors can offset or even undermine the policy’s goals.”
Despite these challenges, the research suggests that carefully designed policies can still make a difference. With small adjustments, such as encouraging reusable bags and addressing secondary effects like trash bag use, bans on single-use plastics could have a meaningful and lasting impact on the environment.
