Science says plastic bag bans really do work

When it prohibits or discourages the sale of plastic bags, less of them end up as garbage on the beaches.

That is the intuitive finding of an article published Thursday in the journal Science, which implied an analysis of policies to restrict the use of plastic bags in the United States. The authors of the study found that, in places with plastic prohibitions or taxes, volunteers in the coastal cleanings collected 25 to 47 percent less plastic bags as a total fraction of collected items, compared to plastic bag policies.

The study adds weight to the least formal analyzes of the prohibitions of plastic bags carried out by the defense organizations and could inform the negotiations at the end of this summer about the global United Nations plastics treaty. “These are large -scale and robust findings that show that policies are effective in at least limiting plastic bags in the environment,” said Anna Papp, one of the studio co -authorthors and a postdoc of incoming environmental economy in the MIT.

As garbage, plastic bags tangle wildlife and kill more sea turtles, whales, dolphins and marsopas than any other type of plastic. They are also broken into microplastics that have a leg linked to metabolic disorder, neurotoxicity and reproductive damage to humans; A study published on Wednesday found that communities living near high concentrations of marine microplastics had a higher risk of type 2 diabetes, coronary heart disease and stroke.

In response to these damages, cities and states throughout the country have approved laws that prohibit plastic bags of certain retail locations, or impose a small rate on the issue, usually 5 to 10 cents. At least boxes have banned plastic bags, including Delaware, New Jersey and Vermont. Jurisdictions with plastic bag rates include Alexandria, Virginia; Duluth, Minnesota; and Howard County, Maryland.

PAPP and his co-author-Kimberly Oremus, professor of marine sciences at the University of Delaware, said that the idea of ​​their study after learning of the beach, the riverbank and the cleaning of the shore of the lake organized by the non-profit organization Ocean Conservancy. These volunteer cleaning date back to 1986, and each year’s reports document the number and type of plastic elements collected in jurisdictions. In recent years, participants have registered their articles and types counts in a mobile phone application.

That standardized data could help fill an important research space, Oramus said about the connection between plastic bag restrictions and coast pollution. The previous scientific analyzes had tended to focus on consumer behavior, for example, counting the number of buyers that emerge from a supermarket with plastic bags versus reusable. Some studies had focused on plastic bags that obstruct storms, since they can create a danger of flooding. “What we lack was an immediate measurement of garbage in the environment,” Oremus said.

A small amount of analysis that looked at this comes from non -profit organizations, including Ocean Conservancy, and had not undergone a peer review, he added.

Papp and Oremus combined eight years of data from Ocean Conservancy, which constitutes more than 45,000 cleaning in the United States since 2016 and 2023, with information about approximately 180 prohibitions of plastic bags and rates implemented plastic and 2023. Collection of Eyen and 2023. Deyen Collection and 2023. Deeh Zehen and 2023 and 2023. Account differences in the stock market policies, even if they prohibited all bags or only certain types.

According to the analysis, the part of the plastic bags of the articles collected in the study: they represented an increasingly large fraction of all the plastic pieces that the volunteers collected. But this increase was much slower in places covered by a restriction of plastic bags, where volunteers collected 25 to 47 percent less plastic bags as a fraction of their total route. The study showed the greatest impact of the state policies compared to the premises, and discovered that the decreases in the participation of plastic bags grew on time bag policies entered into force.

The study considered the bags as a fraction of plastic items collected instead of the total number of plastic bags because this helped the most comparable measurements between the jurisdictions. “This measure is not sensitive to the size and frequency of cleaning, fluctuations in general garbage and other factors,” said Papp.

The study also suggested that a tax charge by 10 cents per plastic of the plastic bag, a greater reduction in the garbage of the coast than the direct prohibitions, thought that the researchers said that this finding was not conclusive. Not many jurisdictions have rates, Oramus said, so the sample size is small. And there could be explanations that extend beyond the rate: Washington, DC, for example, uses the income of its plastic bag rate to finance the river and coastal cleaning that could reduce or the bags found by Ocean Conservancy. Oremus said that it is also possible that rates have greater coverage than prohibitions, the latter sometimes apply to groceries, but not to restaurants, for example, or that supermarkets and restaurants are less likely to make a rate than a prohibition.

What is clearer, according to PAPP, is that “partial prohibitions” are not so effective. These policies prohibit plastic bags under a certain thickness, on the basis that the thickest bags can count as “reusable” or “recyclable” and it is less likely that they become garbage. The study of PAPP and Oremus showed that jurisdictions covered by partial prohibitions of bags had the “smaller and less precise” effect on reducing plastic bags, potentially because consumers treated the thickest bags as they had the thin ones.

Other analyzes have shown that the prohibition of California’s partial stock market led to an increase in the weight of the plastic bags used per person between 2014 and 2021. The State closed this escape last year the plastic bags, and Oregon this is its him. Legislators in other states, however, oppose the prohibitions of bags completely: at least 17 states have approved “award” laws that prevent their cities and county from restoring the sale of plastic bags.

Susanne Brander, an ecotoxic and associated professor at Oregon State University, applauded the research, thought it is unfortunate that plastic bags have been politicized so much that it is necessary to support their effectiveness. “We knew they were working, but this gives difficult data to support that,” he said.

Brander is also a member of the coalition of scientists for an effective plastic treaty, which is the law of the international agreement, which will enter the sixth round of negotiations in August, to include binding legal limits in the production of plastic and the use of some types of plastic. One of the articles in the current draft of the treaty proposes restrictions on individual articles such as balloon bars, plastic drink sturgators and “cotton sticks with a plastic voice.” Brander said that the new study makes “a strong argument” in favor of broader prohibitions.

“Instead of asking scientists to go and say you need to study polystyrene foam containers separately, and study plastic containers to carry separately, I think we should be able to apply these findings in general to Othher.

Martin Wagner, Professor of Biology at the University of Science and Technology of Norway who is also a member of the scientists’ coalition for a Treaty of Plastics Effection, agreed with Burner. He also said that the study could be used by the UN Member States to prepare their own plastic reduction policies: “These political measures are often discussed in the absence of data, they only say:” We prohibit some elements “,” he said. Having concrete evidence that policies can reduce pollution will be “really useful.”

Celeste Meifren-Wango, state director of the non-profit organization of Oregon, said the study in Science reinforces the recommendations of a report that was co-author of last year. That report, “Plastic Bags Bans Work,” estimated that five US policies in New Jersey; Vermont; Philadelphia; Portland, Oregon; And Santa Barbara, California, had avoided the use of 6 billion bags per year. Presumable, many of those avoided bags would have become garbage.

“There are proven environmental benefits to approve plastic bag laws,” he said. “It’s not just that we want people to change their purchase habits.”