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Ever since their invention in 1959, plastic bags have become synonymous with shopping. For many people, it’s difficult to imagine a quick grocery run without the crinkle of a plastic bag, and even harder to believe that using an alternative could make a meaningful difference in reducing plastic pollution — but a new national study suggests that, in many places, it already has.
A 2021 global survey found that plastic bags accounted for 14% of 12 million marine litter items gathered during beach cleanups — making them by far the most common type of trash in the study. They’re lightweight, rarely recycled, and easily caught and transported by winds, making them especially likely to end up in waterways, where they can persist for decades. This combination of durability and disposability has made plastic bags one of the most stubborn contributors to environmental pollution, particularly along coastlines.
However, a growing body of evidence suggests that instituting regulations on plastic bag usage — where California has long been a national leader — has had a real effect on how often such waste shows up on and near beaches.
In a study published Thursday in Science, researchers Anna Papp of Columbia University and Kimberly Oremus of the University of Delaware found that local and state plastic bag policies enacted from 2016 to 2023, including bans and fees, reduced by as much as 47% the share of waste consisting of plastic bags that is collected during shoreline cleanups. (California’s state-wide rules requiring a $0.10 charge of reusable bags was passed in 2014, and went into effect two years later — though industry watchers largely say while the law was well-intended, its implementation has been ineffective.)
The findings offer clear evidence that legislation can be used to curb plastic pollution — a growing concern as global waste generation is projected to more than triple by the end of the century. As of 2025, more than 100 countries have enacted national or local regulations on plastic bags, and 175 nations are negotiating what could become the world’s first legally binding United Nations treaty to end plastics pollution, so such data may prove essential in determining what environmental policy strategies actually work.
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In the study, researchers analyzed information from more than 45,000 beach cleanups conducted between January 2016 and December 2023 that is in a database maintained by the Ocean Conservancy, an environmental advocacy nonprofit. The researchers then cross-referenced the data with 182 local bag policies enacted over the same time period in ZIP Codes that had shoreline cleanups, and then applied a series of statistical methods to isolate the effects of these policies.
They found that plastic-bag litter dropped significantly in areas with bag laws, even as the national share of plastic bags found during cleanups increased to 6.7% in 2023 from 4.5% in 2016. No similar decline was observed for other types of plastic litter, including plastic straws, bottles, caps and containers, suggesting that the effects were specific to the target policies and not coincidental due to general trends in plastic usages.
Perhaps even more striking, the study found evidence suggesting that the structure of a given bag policy — whether it imposes a full ban, partial ban or a fee — played a crucial role in how much plastic waste it actually reduced.
Full bans prohibit all single-use plastic bags at checkout, while partial bans primarily target thin, single-use plastic bags, often allowing for thicker plastic bags to remain in circulation as so-called reusables. Fees, meanwhile, charge customers a small amount for each bag they take at checkout.
Although the study found that there were relative decreases in plastic litter as a result of both bans and fees, the magnitude of the decrease was larger for fee-based policies compared with full bans and especially partial bans, which were least effective. This suggests that how a policy is designed may matter as much as whether it exists at all — a key insight for lawmakers hoping to craft effective environmental legislation.
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California’s history of efforts to curb plastic waste serve as a prime example of this finding. With the passing of Senate Bill 270 in 2014, which barred the use of single-use plastic shopping bags in many retail settings, California became the first U.S. state to enact a plastic bag ban. Although this ban initially reduced plastic bag litter, it only prohibited the use of bags thinner than 2.25 millimeters, permitting grocery stores and large retailers to charge for thicker plastic bags and ultimately leading to an unexpected jump in plastic bag waste. This is reflected by California’s 2021 Disposal Facility-Based Waste Characterization study, overseen by CalRecycle, which reported that plastic bag waste rose to 231,072 tons in 2021 from 157,385 tons in 2014 — a nearly 47% increase.
“It was a nasty loophole,” said Meredith McCarthy, the senior director of community outreach and partnerships at Heal the Bay, a Santa Monica-based nonprofit that organizes coastal cleanups and advocates for plastic reduction policies. “I think a lot of people were thinking: ‘Wait, we banned it? And now we use more? How is that possible?””
Even so, McCarthy, who’s spent 20 years monitoring trends in plastic pollution on Los Angeles beaches, said that even this imperfect policy has helped implement a noticeable change. “It’s almost rare now to find a plastic bag,” McCarthy said.
The study also found evidence that plastic bag laws may reduce harm to marine life: in areas with bag policies, there was a 30% to 37% reduction in entangled animals relative to areas without such laws. Although the researchers caution that these findings are imprecise, in part because of the fact that we don’t fully understand how wildlife interacts with plastic bags compared with other shoreline litter, the results do point to a potential environmental benefit of regulating single-use plastics.
In September, Gov. Gavin Newsom signed Senate Bill 1053, banning all single-use plastic bags statewide. In theory, starting Jan. 1, 2026, such bags will disappear entirely from checkout lines altogether — meaning customers in California will need to use a reusable bag, pay for a paper bag, or hand carry their purchase.
California’s new ban won’t solve the plastic problem overnight, but this research shows that the right kind of policy — one with stricter laws and fewer loopholes — can make a measurable difference. Want proof? Just head to your nearest beach.
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