When you prohibit or discourage the sale of plastic bags, fewer of them end as a litter on the beaches.
It is the intuitive discovery of a Document published Thursday In the journal Science, which involved an analysis of policies aimed at restricting the use of plastic bags in the United States. The authors of the study found that, in places with prohibitions of plastic bags or taxes, coastal cleaning volunteers collected 25 to 47% less plastic bags as a total fraction of the articles collected, compared to places without plastic bag policies.
The study adds weight to less formal analyzes of the prohibitions of plastic bags carried out by defenders’ defense organizations and could shed light on the negotiations later this summer on the United Nations world plastics. “These are large-scale results that show that these policies are effective in at least limiting plastic bags in the environment,” said Anna Papp, one of the study co-authors and an incoming postdoc environmental economy.
As a litter, the plastic bags tangled from fauna and kill more Sea turtles, whales, dolphins and porpoises than any other type of plastic. They also break down into microplastics which have been linked to Metabolic disorder, neurotoxicity and reproductive damage in humans; A Study published Wednesday have found that communities living near concentrations of marine microplastics presented an increased risk of type 2 diabetes, coronary disease and stroke.
In response to these misdeeds, cities and states across the country have adopted laws that prohibit plastic bags from certain retail locations, or impose a modest sum – generally from 5 to 10 cents. At least a dozen states have banned plastic bags, including Delaware, New Jersey and Vermont. Jurisdictions with plastic bag costs include Alexandria, Virginie; Duluth, Minnesota; And Comté de Howard, Maryland.
PAPP and his co -author – Kimberly OREMUS, Marine science professor at Delaware University – said they had the idea of their study after learning about the cleaning of the beach, the shore and the lake organized by the non -profit ocean conservance. These Volunteer cleanings date back to 1986And the reports of each year document the number and type of plastic articles collected in the courts. In recent years, participants have recorded their counts and types of items in a mobile phone application.
These standardized data could help fill an important research gap, said Oremus, on the link between restrictions on plastic bags and shore pollution. Previous scientific analyzes had tended to focus on consumer behavior – for example, counting the number of buyers that emerge from a supermarket with plastic and reusable bags. Some studies were focused on plastic bags obstructing storm drains, as this can create a risk of flooding. “What we were missing was a direct measure of the litter in the environment,” said Orimus.
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A small number of analyzes examining this came from non -profit organizations, Including the Ocean ConservanceAnd had not been reviewed by peers, she added.
PAPP and Orimus have combined eight years of Ocean Conservancy data – constituting more than 45,000 cleaning in the United States between 2016 and 2023 – with information on around 180 prohibitions of plastic bags and the costs implemented between 2017 and 2023. They analyzed the collection of plastic bags in zipped codes with and without restrictions of plastic bags, and took into account bag policies, in particular whether they have prohibited all bags of bags or are not into account.
According to the analysis, the part of the plastic bags of the articles collected increased during the study period: they represented an increasing fraction of all the plastic pieces that the volunteers picked up. But this increase was much slower in the places covered by a plastic bag restriction, where volunteers collected 25 to 47% less plastic bags as a fraction of their total transport. The study has shown the highest impact of policies in terms of local policies, and revealed that the decreases in the share of plastic bags have increased over time after the entry into force of bag policies.
The study considered bags as a fraction of plastic articles collected rather than the total number of plastic bags, as this has helped make the measures more comparable between the courts. “This measure is not sensitive to the size and frequency of cleaning, the fluctuations in global litter and other factors,” Papp said.
The study also suggested that taxes – as a charge of 10 cents per plastic bag – cause a greater reduction in the shore litter than outright prohibitions, although researchers have declared that this finding was not conclusive. Not many jurisdictions have costs, said Oremus, so the size of the sample is small. And there could be explanations that extend beyond the costs themselves: Washington, DC, for example, uses the income of its plastic bag costs to finance the River and Shore L’Oremus cleaning said that it is also possible that the costs have greater coverage than prohibitions – these are sometimes applied to grocery stores but not to restaurants, for example – or the supermarkets are less. likely to flout costs than a ban.
According to PAPP, what is clearer is that “partial prohibitions” are not as effective. These policies prohibit plastic bags below a certain thickness, on the basis that thicker bags can count as “reusable” or “recyclable” and are less likely to become litter. The study by PAPP and Orimus showed that the jurisdictions covered by partial bag prohibitions had the effect “the smallest and least precise” on the reduction of the litter of plastic bags, potentially because consumers treated the thicker bags just as they had the fine.
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Other analyzes have shown that the ban on partial bags in California has led to a Increase in the weight of plastic bags used per person between 2014 and 2021. The state closed this escape last year By prohibiting plastic bags and Oregon Followed out with his own bag prohibition Earlier this month. Legislators of other states, however, completely oppose the prohibitions of bags – at least 17 states have passed “pre-emption»Laws preventing their cities and counties from restricting the sale of plastic bags.
Susanne Brander, eco -with an associate teacher at Oregon State University, applauded research, although she said that it was regrettable that plastic bags have become so politicized that a scientific study is necessary to support their effectiveness. “We knew they were working, but that gives difficult data to support this,” she said.
Brander is also a member of the scientists’ Coalition for A Effective Plastics Treaty, which pleads for the international agreement – which will enter its sixth cycle of negotiations in August – to include liaison limits on plastic production and the use of certain types of plastic. One of the articles of draft From the treaty offers restrictions on individual articles such as balloon sticks, plastic drinking agitators and “cotton sticks with plastic rod rod”. Brander said that the new study was “a strong argument” in favor of broader prohibitions.
“Rather than asking scientists to go and say that you have to study the polystyrene containers separately, and study the plastic take-out containers separately, I think we should be able to apply these results largely to other prohibitions for harmful products,” she said.
Martin Wagner, professor of biology at the Norwegian University of Science and Technology, who is also a member of the Scientists Coalition ‘for an effective plastic treaty, agreed with Brander. He also said that the study could be used by UN member states to develop their own plastic reduction policies: “These political measures are often discussed in the absence of data-they simply say:” certain elements prohibitions, “he said. Having concrete evidence that policies can reduce pollution will be “really useful”.
Celeste Meiffren-Swango, director of the Oregon non-profit environment, said that the study in science is strengthening the recommendations of a report she co-written last year. This report, “Plastic bag prohibitions work“Said five American policies in New Jersey; Vermont; Philadelphia; Portland, Oregon; And Santa Barbara, California, had prevented the use of 6 billion bags per year. Praisemboubly, many of these avowed bags would have become a litter.
“There are environmental advantages proven to adopt laws on plastic bags,” she said. “It is not only that we want people to change their purchasing habits.”