Plastic bag bans help, but they aren't enough to stop pollution

For years, thin plastic bags have been one of the most visible symbols of pollution – blowing through streets, choking marine wildlife, and breaking down into microplastics that contaminate ecosystems.

Now, a new study led by researchers at the University of Delaware and Columbia University offers the clearest evidence yet that bag bans and fees do make a difference.

By analyzing data from tens of thousands of beach cleanups across the United States, the researchers found that jurisdictions with plastic bag laws saw a significant drop – between 25% and 47% – in plastic bags as a share of shoreline litter.

The study is the first large-scale analysis to connect local policy with direct environmental outcomes, rather than relying on consumer checkout data alone.

“A lot of the previous economics literature on plastic bag policies has used checkout data at the store level,” said lead author Anna Papp, an environmental economist at Columbia. “We were excited to add to that a direct measurement of plastic litter on these shorelines.”

Understanding the plastic bag problem

Americans use billions of plastic bags each year – often for just minutes – yet these bags can take hundreds of years to break down.

Most end up in landfills, where they occupy space without decomposing, or escape into the environment, littering streets, waterways, and natural areas.

Because they’re lightweight, they easily blow out of trash bins and landfills, creating widespread pollution that’s difficult and costly to clean up.

Once in the environment, plastic bags wreak havoc on wildlife and ecosystems. Animals, particularly marine life, often mistake them for food or become entangled in them, leading to injury or death.

Microplastics from degrading bags enter the food chain, raising concerns about long-term health effects in both wildlife and humans.

Volunteers help map plastic waste

The idea for the study began when co-author Kimberly Oremus, a marine policy expert at the University of Delaware, noticed that volunteers at Delaware beach cleanups were using an app called Clean Swell to track the litter they picked up.

The app feeds into the Ocean Conservancy’s TIDES database, which collects crowdsourced data from thousands of cleanups around the world.

“When we found the database that had information on different shoreline cleanups, we realized we could look at the composition of litter before and after a policy to see what effect it had,” Oremus said. “And then we could compare that to places that never got a plastic bag policy.”

With no federal ban on plastic bags in the United States, the researchers had a rich dataset of hundreds of local and state-level laws to compare.

Between 2007 and 2023, they compiled over 600 distinct policies, allowing them to assess a wide range of regulations and their impacts.

Bans and fees differ greatly

While it might seem obvious that banning or taxing plastic bags would reduce litter, the magnitude of the effect surprised the team.

“There are so many pathways a bag can take from the checkout line at the store,” Oremus said. “It’s great to see a policy that works in such a clearly measurable way.”

Interestingly, the research also showed that some types of policies work better than others.

State-level laws tended to have a stronger impact than city or county ordinances, and fees – perhaps counterintuitively – were more effective at reducing litter than outright bans.

Papp noted that this could be because fees encourage people to bring reusable bags, while bans may be more easily circumvented with loopholes or substitutions.

The researchers also observed that the policies had the biggest impact in areas that started with higher levels of plastic bag pollution, suggesting that public buy-in and visible local problems may help drive compliance and effectiveness.

Plastic decline slows, not stops

Despite the success of bag policies in reducing local litter, the overall share of plastic bags among shoreline trash is still increasing – just not as quickly in areas with bans or fees.

“We’re still getting more plastic bags on shorelines as a percentage of all the cleanup items over time,” noted Oremus. “It’s not eliminating the problem, it’s just making it grow more slowly.”

This sobering trend highlights the limitations of local policies when facing a global problem.

Plastic production and consumption continue to rise, and single-use items remain deeply embedded in supply chains and consumer habits.

“Ours is the first large-scale study to use hundreds of policies and tens of thousands of cleanups to look at their effects,” Papp said. “But it is important to keep in mind that this is a relative decrease in affected areas compared to areas without policies.”

Bags are just the start

With the United Nations Environment Program preparing for its next round of negotiations on an international plastic treaty in August 2025, the study offers timely evidence that policy can make a tangible difference.

“Overall, our findings do show that plastic bag policies are broadly effective in limiting litter along shorelines,” Papp said. Yet, plastic bags remain just one piece of the puzzle.

The researchers hope their work will help policymakers think beyond local or single-product solutions and push for more comprehensive strategies.

Plastic bag bans aren’t a silver bullet, but they’re one of the tools that clearly work – and that gives scientists something to build on.

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