Studies confirm that a small tax definitely helps curb plastic pollution

Plastic bags are everywhere, and too many slip into rivers and onto beaches. A new analysis finds that policies that either charge a small fee per bag or prohibit them outright cut the share of bags found during shoreline cleanups by 25 to 47 percent.

The study combed through hundreds of city, county, and state rules passed between 2017 and 2023. It matched those policies to more than 45,000 volunteer cleanups across the United States to see what actually changed on the ground.

Who ran the study

The research was coauthored by Kimberly L. Oremus of the University of Delaware’s School of Marine Science and Policy (UDEL).

Oremus and her collaborator set out to measure litter, not just shopping behavior, so the results speak to what ends up in nature.

The team relied on citizen science, meaning trained volunteers recorded what they collected during beach, river, and lake cleanups.

They drew on TIDES, a public database that stores those counts in one place so researchers can analyze patterns across time and place.

Studying plastic bag policies

To isolate the effect of bag policies, the authors used a Difference-in-Differences (DiD) approach that compares places with and without new laws over the same period.

That design helps rule out unrelated trends that affect everyone, such as national shifts in shopping or packaging.

The headline result is simple. In communities with full bans or fees, the share of plastic bags in the litter mix fell relative to similar places without policies, and the decline grew in the years after a law took effect.

State level rules tended to be more reliable in the data than city or county policies. Effects looked similar along coasts and rivers, with hints of larger gains along lakes where winds and currents spread litter differently.

Plastic policy: Fees vs. bans

Fees change the default at every checkout and discourage taking a bag when you do not need one, which reduces both thin and thicker bag use.

Other evidence points in the same direction outside the United States. England reports an almost 98 percent drop in single use carrier bags at major retailers since its charge began.

Policies that only restrict thin bags often allow thicker plastic labeled as reusable.

Those partial bans showed the smallest and least precise effects in the analysis, which is consistent with shoppers substituting one kind of plastic for another.

Some states also pass preemption laws that block cities and counties from regulating bags at all. When local governments cannot act, the study’s data suggest statewide policies become especially important.

Wildlife and entanglement

The cleanup records include notes on animals found entangled in debris.

In areas with bag policies, the presence of entangled animals dropped by roughly 30 to 37 percent, although the authors caution that the estimates are imprecise and more data are needed.

That finding aligns with what we know about single-use-plastics. Thin bags linger in water and along shorelines, where they can snag, smother, or be eaten by turtles, birds, and fish.

Many studies track what happens at store checkouts, but fewer track what ends up outdoors. Shoreline cleanups offer a window into that last step in the chain from purchase to pollution.

Across the study period, the share of bags among collected items rose overall, but it rose less where bag laws existed. That pattern is exactly what you want to see if policies are slowing the flow of litter into the environment.

Global plastic policy steps

A small, universal fee is a simple tool that nudges behavior without banning choices. Full bans can work too, and the analysis shows both approaches reduce the share of plastic bags found during cleanups.

The mix of policies should match local conditions. In places with more bag litter to begin with, impacts were largest, so targeting high problem areas with fast action can deliver quick gains.

Plastic bag rules are only one part of the picture. Negotiators from 175 countries are working toward a plastics treaty under UNEP that could standardize action on a wider set of products and chemicals.

The study notes that bottles, caps, and other items did not decline when bag policies passed. That is a signal that targeted rules for other single use products would be needed to curb overall litter.

Adopt a modest fee or a full ban that applies across retail and restaurant settings, and keep the text simple so it is easy to enforce. Pair the policy with clear signs at checkout and with retailer reporting that tracks compliance.

Measure results in the same way the researchers did. Recruit volunteers, log items in TIDES, and watch how the litter mix changes year over year so the policy can be adjusted as needed.

The study is published in Science.

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