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That extra fee at the grocery store for a plastic shopping bag isn’t just an inconvenience –– it is actually making a difference for marine ecosystems, according to a new study.
Policies that ban or impose fees on plastic bags are associated with a 25% to 47% decrease in plastic bag litter in shoreline cleanups, according to a study published Thursday in the journal Science.
Plastic litter is a big risk to the health of marine ecosystems, and the problem is growing, said lead study author Dr. Anna Papp, an environmental economist and incoming postdoctoral researcher at the Massachusetts Institute of Technology.
The United States has no federal-level policy on plastic bags, so researchers analyzed 180 local programs, including full bans, fees on shopping bags and partial bans –– which sometimes have special regulations such as requiring thicker plastics to make shopping bags reusable.
Researchers then analyzed data from more than 45,000 US shoreline cleanups to compare the litter before and after the policy was passed as well as the differences between areas with and without a policy, Papp said.
“The main finding is that these policies led to a decrease in plastic bags as a share of total items collected,” she said.
Other studies have shown that plastic bag policies affect how many bags consumers use, said Dr. Erin Murphy, manager of Ocean Plastics Research for the Ocean Conservancy.
But this most recent research “really takes it to the next level, showing it’s not only reducing the amount of bags we’re using, but it’s actually achieving our broader objectives of environmental cleanliness,” she said.
Plastic bags’ impact on people and animals
Plastic bag pollution is harmful to both animals and humans.
On beaches or other outdoor spaces, plastic pollution can have a negative impact on tourism or the value of spending time in nature, Papp said.
Plastic bag litter is particularly dangerous to marine animals for two reasons, Murphy said. First, they enter the environment more easily than other types of plastic.
“They’re hard to recycle, they’re single-use, and they’re lightweight, and so they blow very easily in the wind. Even if we’re trying to properly manage them, it’s easy for them to escape waste management systems and get into the environment,” she said.
Second, once they enter the environment, plastic bags can lead to population-level effects on marine species, Murphy said.
Many species, including marine mammals and sea turtles, will eat the plastic bags, obstructing the gastrointestinal tract and preventing them from eating until they die, she said. Plastic bags can also entangle wildlife, keeping hatchling sea turtles from reaching the ocean and shading coral reefs, all of which can lead to disease and death for marine species.
“In 2024 alone, our International Coastal Cleanup volunteers cleaned up over 500,000 grocery bags from the environment and 500,000 other plastic bags, totaling more than a million different plastic bag types from the environment,” Murphy said. “They’re always in our top 10 items found in the environment, and that alone is an issue.”
Making a difference
While bans and fees on plastic bags are helping, they are not eradicating the problem, Papp said.
“Plastic pollution is a growing global problem,” she said. “The overall percentage of plastic bags is still increasing … This increase is just slower in places with policies.”
The evidence suggests some policies are more effective than others: Full bans made a bigger impact than partial bans, and fees seemed better than bans, said study coauthor Dr. Kimberly Oremus, an associate professor at the University of Delaware School of Marine Science and Policy.
“One hypothesis is that in at least some cases, the revenue from fees is being used to further reduce litter. In Washington, DC, for example, they use the revenue from plastic bag fees to clean up river shorelines,” Oremus said.
However, the hypothesis has not been investigated, and there is not yet enough data to say for sure that fees are more effective than bans, she said.
More must likely be done outside of these policies as well, Papp said. The United States needs regulations not just on the consumption of plastic bags but also on the production and supply of them, she added.
There are also steps you can take so your plastic shopping bag doesn’t end up in the environment, Papp said.
For one, if you do use a plastic bag, don’t let it fly away and create litter. Then, properly dispose of it — for example, you can take it to a plastic bag recycling station, she said.
And you can always go back to the three R’s, said Dr. Rebecca Taylor, an assistant professor of agricultural and consumer economics at the University of Illinois Urbana–Champaign.
Reduce the number of plastic bags you use, reuse them when you can and recycle them when you must.
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