Shoreline trash slashed by half thanks to plastic bag bans

By Stephen Beech

Plastic bag bans really do work with shoreline litter slashed by almost half, according to new research.

The introduction of fees or bans for the ubiquitous carriers has led to a 47% drop in litter on the coast and beaches, say scientists.

And the decrease rose in magnitude over time - with no evidence of the rates rebounding.

Plastic shopping bags are among the biggest culprits of plastic pollution in the ocean and along coastlines.

They can entangle birds and marine life and break down into harmful microplastics.

More than 100 countries have now introduced bans or fees for plastic bags as awareness of the problem has grown.

But what effect those policies were having on the amount of plastic litter in the marine environment had not been full evaluated until now.

The new study, published in the journal Science, took a thorough look at plastic bag bans and fees across the United States to gauge their effectiveness.

Researchers from the University of Delaware and Columbia University found that the fees or bans led to a 25% to 47% decrease in plastic bags as a share of total items collected in shoreline litter-picks compared to areas without such policies.

Study co-author Professor Kimberly Oremus got the idea for the study when she learned that volunteers at coastal beach clean-ups in Delaware were using an app called Clean Swell to track the litter collected.

The figures go into the Ocean Conservancy’s Trash Information and Data for Education and Solutions (TIDES) database, which keeps crowdsourced records from thousands of clean-ups around the world each year.

Prof Oremus, from the University of Delaware's School of Marine Science and Policy, said: “When we found the database that had information on different shoreline clean-ups, we realised we could look at the composition of litter before and after a policy to see what effect it had.

“And then we could compare that to places that never got a plastic bag policy.”

Study lead author Dr. Anna Papp, of Columbia University’s School of International and Public Affairs, says the plastic collected in shoreline clean-ups can serve as a proxy for the total amount of plastic litter in the local marine or aquatic environment.

She said: “A lot of the previous economics literature on plastic bag policies has used checkout data at the store level.

“So we were excited to add to that a direct measurement of plastic litter on these shorelines.”

The research team looked at tens of thousands of shoreline clean-ups and hundreds of local policies to determine how the legislation worked in terms of reducing plastic litter in the environment.

The researchers focused on the United States because it has no federal plastic bag policy, allowing them to compare the effects of different types of policies at the town, county and state level within a single country.

While it might not seem surprising that banning or taxing plastic bags would reduce litter, Prof Oremus says the results were more robust than she had expected.

She said: “There are so many pathways a bag can take from the checkout line at the store.

“It’s great to see a policy that works in such a clearly measurable way.”

Dr. Papp was surprised to find that around one-in-three Americans are living in an area with some sort of plastic bag policy in place.

She said: “It was interesting to quantify the reach of the policies.

“We compiled over 600 policies for 2007-2023, with a lot of variation in their scope and geographic scale.”

The study also found that some legislation seemed to be more effective than others in reducing plastic litter.

They discovered more robust impacts from state-level policies than town-level policies, with fees appearing to reduce litter even more than bans, though more research is needed to understand why.

Another finding was that the bag bans and fees were most effective in places where the plastic bag litter problem was more severe to begin with.

But the research team warned that despite bans and fees working to reduce the percentage of plastic bags on the shorelines, the overall percentage of plastic bags is increasing in both places with and without the policies.

It is just increasing less in places with the policies than those without.

That’s because plastic pollution is growing in general - and bag policies can only "mitigate" some of its impacts, according to the researchers.

Prof Oremus said: “We’re still getting more plastic bags on shorelines as a percentage of all the clean-up items over time.

“It’s not eliminating the problem, it’s just making it grow more slowly.”

With the United Nations Environment Program announcing the next round of negotiations on an international plastic treaty will happen in August this year, the researchers said their study highlights the opportunity for a more comprehensive approach to the problem.

Dr. Papp said: “Overall, our findings do show that plastic bag policies are broadly effective in limiting litter along shorelines."

She added: “Ours is the first large-scale study to use hundreds of policies and tens of thousands of clean-ups to look at their effects.

"But it is important to keep in mind that this is a relative decrease in affected areas compared to areas without policies.”