In recent years, in cleaning up tens of thousands of coastlines across the United States, volunteers have recorded parts of garbage pulled from the edges of lakes, rivers and beaches in a global database.
One of the most common entries? Plastic bag.
However, a study published in Science on Thursday shows that plastic bags require or are prohibited from paying for them, fewer bags on the edge of the water will be found in places across the United States.
Lightweight, abundant thin plastic bags often slide off garbage cans and recycle bins, moving through the wind and going in the waters. There, poses serious risks to wildlife. They are also classified as harmful microplastics discovered almost anywhere on the planet.
Using data complied by the nonprofit Ocean Conservancy, the researchers analyzed the results along with a sample of 45,067 coastline cleanup results between 2016 and 2023 and 182 local and state policies enacted to regulate plastic shopping bags between 2017 and 2023.
They found that the adopted plastic bag policy reduced the share of shoreline plastic bag litter by 25% to 47% compared to areas without policy. The longer the policy, the greater the reduction.
“We’ve seen a lot of people who have had a lot of trouble with us,” said Anna Papp, a fellow Massachusetts Institute of Technology and a fellow postdoc.
The study outlined various types of policies, including a complete ban, a partial ban that allows several thick plastic bags that are considered “reusable,” and charging a fee to bag shoppers at checkout. Prohibitions, such as New York, that are considered complete, may allow exceptions such as food takeout. They found that a complete ban and fees lead to a significant reduction in coastline bags over a partial ban.
The total amount of plastic bag fragments found on the coastline with or without policies during the study period, with or without policies, was significantly less ban on plastic bags and increased fees than those without them.
“It’s blowing the speed of plastic bag garbage,” said Kimberly Olemas, another author and an environmental economist and associate professor at the University of Delaware. “It’s not turning it back on, it’s not eliminating it.”
To test the overall trends in each area, researchers also tracked other items such as bottles and straws. They were unable to find a decline in those and reinforced the findings that a decrease in the proportion of plastic bags is tied to area bag policies.
Findings also suggest that policies may reduce wildlife entanglement by shoreline plastic bags based on a decrease in the number of entangled animals that died or injured during cleanup. However, more information is needed to determine the connection specifically, the researchers said.
Hundreds of state and local governments have adopted a ban or fee for single-use plastic bags, but in some states, local governments have moved to preemptively block bag restrictions. Globally, several countries have adopted plastic bag policies. The timing of this study is relevant as countries around the world negotiate with UN treaties designed to tackle plastic pollution.
Zoie Diana, an environmental scientist and postdoctoral researcher at the University of Toronto, said she studied plastic pollution and was not involved in the study. Researchers are exciting because they managed to reduce plastic waste by using plastic bag policies.
“It shows that this trend didn’t happen anyway,” Diana said. “These policies are working.”
Using data collected by volunteers, researchers gave the ability to track plastic bag waste over time in the environment, making them robust before and after comparisons and as robust as possible, Pap said.
“This isn’t a single snapshot of plastic trash, but it actually happens over and over again,” she said.
Ocean Conservancy collects data from volunteers in coastline cleanups around the world, primarily via mobile apps, and publishes that data for use by researchers.
Erin Murphy, manager of the organization’s Ocean Plastics Research, said the work demonstrates the potential for data collected by volunteers that contribute to a better understanding of environmental issues.
“When we have these members of our community who are interested in the issue and are willing to collect data for us, it allows us to learn more about what is happening in our environment,” Murphy said.
Researchers emphasized that the ban on plastic bags and fees are not a complete solution to plastic bag contamination, but found to be productive when leaving a small number of bags on the beach.
