Do Plastic Bag Bans Reduce Shoreline Plastic Litter?

This study asks whether plastic bag bans and fees reduce shoreline plastic litter. The authors combine data from 611 U.S. state, county, and town plastic bag policies implemented between 2017 and 2023 with evidence from 45,067 citizen-science shoreline cleanups. Using difference-in-differences methods, they estimate that bag policies reduce the share of plastic bags among collected items by 25 to 47 percent relative to areas without policies. Both bans and fees are effective, though fees may have somewhat larger impacts, while partial bans produce smaller effects. There is also suggestive evidence of a 30 to 37 percent reduction in wildlife entanglement .

Full Citation and Link to Article

Papp, A., & Oremus, K. L. (2025). Plastic bag bans and fees reduce harmful bag litter on shorelines. Science, 388, eadp9274. https://doi.org/10.1126/science.adp9274

Extended Summary

Central Research Question

The central research question of this study is whether plastic bag bans and fees effectively reduce plastic bag litter on U.S. shorelines. While many jurisdictions worldwide have adopted such policies in response to concerns about marine pollution, systematic evidence linking these policies to reductions in actual environmental litter has been lacking. The authors specifically investigate how different types of policies—full bans, partial bans, and bag fees—affect the prevalence of plastic bags found in shoreline cleanup efforts across diverse ecosystems, including coasts, rivers, and lakes. They also explore whether such policies reduce wildlife entanglement with plastic debris.

Previous Literature

Prior research on plastic bag policies has primarily focused on consumer behavior rather than environmental outcomes. Studies using retail scanner data indicate that local bans or fees can reduce thin disposable plastic bag use at checkout counters, although substitution often occurs toward paper bags, reusable bags, or thicker plastic bags. Evidence from international cases such as England, Wales, Taiwan, and South Africa has shown mixed results regarding bag consumption, with some demonstrating sustained reductions and others only temporary declines. However, the critical gap in the literature is whether such reductions in consumption translate into measurable declines in plastic litter in natural environments. Some reports have presented before-and-after statistics from isolated cases, but these often lack robust controls for time trends or sample size. This study builds on calls from scholars and policymakers for more systematic evaluation of bag policies’ effects on the environment, especially as negotiations for a global plastics treaty progress and as some U.S. states preempt local bag regulations.

Data

The study draws on two major data sources. First, the authors compile a comprehensive dataset of 611 plastic bag policies across the United States at the state, county, and town levels from 2008 through 2023. These policies include full bans, partial bans, fees, and preemption laws, though only policies implemented between 2017 and 2023 are included in the main analysis to align with cleanup data availability. As of December 2023, about one in three Americans—approximately 116 million people—lived in jurisdictions with a plastic bag law. Second, the study uses citizen science data from 45,067 shoreline cleanups recorded between January 2016 and December 2023. These cleanups, coordinated by the Ocean Conservancy through the TIDES database, document litter collected across coasts, rivers, and lakes. Plastic bags were the fifth most common item found, making up an average of 4.5 percent of items collected, though rising to 6.7 percent by 2023. Importantly, 65.6 percent of cleanups were within 10 kilometers of the coast, and 86.6 percent were in watersheds that drained to the ocean, ensuring relevance for marine pollution. The authors match policy coverage to affected zip codes and grid cells, enabling analysis of treatment and control areas.

Methods

The empirical strategy is based on difference-in-differences models that exploit the staggered rollout of plastic bag policies across U.S. jurisdictions. The authors employ both traditional two-way fixed effects models and more recent estimators robust to heterogeneous treatment effects. They compare the share of plastic bags among cleanup items in treated areas before and after policy implementation to trends in untreated areas. To test robustness, the analysis uses multiple levels of spatial and temporal aggregation, including 0.1° grid cells (~11 km) and zip code–year panels, as well as monthly, quarterly, and annual time aggregation. Event-study analyses are conducted to examine dynamic effects and to test for pre-trends. Placebo tests assess whether other litter items (plastic bottles, caps, straws, containers) changed after policies, which would indicate confounding. Additional robustness checks include excluding years coinciding with COVID-19 disruptions, restricting to cleanups of different sizes, and controlling for cleanup frequency. The authors also explore heterogeneity by policy type (ban, partial ban, fee), geographic scope (state, county, town), shoreline type (coast, river, lake), and baseline prevalence of plastic bags. Finally, they analyze the effect of bag policies on observed animal entanglements in shoreline data.

Findings/Size Effects

The results indicate that plastic bag bans and fees substantially reduce the prevalence of plastic bag litter on U.S. shorelines. Across five estimators, the share of plastic bags among collected items decreases by 25 to 47 percent relative to areas without policies. This effect persists across robustness checks and grows stronger over time after policy implementation, with no evidence of rebound effects within the first five years. Both bans and fees are effective, but fee-based policies may have larger impacts, although estimates are noisier due to fewer cases. Partial bans generate the smallest and least precise effects, likely due to exemptions allowing thicker plastic bags. At different geographic scales, state-level policies show the most robust reductions, but county and town policies are also effective. The effectiveness extends across coasts and rivers, with suggestive evidence of larger reductions along lakes. Importantly, bag policies yield the largest benefits in areas with high baseline shares of plastic bag litter, where plastic bags constituted an average of 13.2 percent of cleanup items before policy adoption. Spillover tests do not reveal strong evidence of cross-border litter shifts, suggesting that effects are localized and not offset by neighboring jurisdictions. Regarding ecological impacts, the authors find suggestive evidence of a 30 to 37 percent reduction in observed wildlife entanglements in areas with policies, although this result is imprecise and not statistically robust across all specifications. Placebo tests confirm that declines in plastic bags were not mirrored in other categories of plastic litter, strengthening the causal interpretation.

Conclusion

The study concludes that plastic bag bans and fees are broadly effective in reducing shoreline plastic bag litter in U.S. jurisdictions. By linking policies directly to environmental outcomes, the analysis fills a critical gap in the literature and provides evidence for policymakers considering bag regulations or negotiating international agreements on plastics. The reductions observed—25 to 47 percent fewer plastic bags in shoreline litter—represent substantial improvements in affected areas, especially where bag litter was initially high. Although fees may have larger effects than bans, more data are needed to confirm this. Partial bans appear least effective, underscoring the importance of policy design. The evidence on wildlife entanglement, while suggestive, calls for further research. The authors note that the effectiveness of these policies could be even greater outside the United States, where waste mismanagement is more severe, though local enforcement capacity will matter. Overall, the findings demonstrate that expanding plastic bag bans and fees can meaningfully reduce plastic pollution and potentially improve ecosystem health, though they cannot by themselves eliminate plastic debris. Future policies targeting other common litter categories, such as bottles and caps, may be necessary to achieve broader reductions in marine and freshwater plastic pollution.