Quantcast

Biodegradable Bags Buried for 3 Years Still Work

Popular
Lloyd Russell / University Of Plymouth

The advantage of biodegradable shopping bags is supposed to be that they will not linger as long in the natural environment as conventional plastic bags. However, a new study from the University of Plymouth suggests that might not be the case.


The study, published in Environmental Science and Technology Sunday, found that bags billed as biodegradable could still carry around five pounds of groceries after being buried in soil or submerged in sea water for three years, The Weather Channel reported.

"After three years, I was really amazed that any of the bags could still hold a load of shopping. For biodegradable bags to be able to do that was the most surprising," study leader Imogen Napper said.

Researchers compared five types of bags widely available in the UK, according to The Guardian: two oxo-biodegradable bags, a biodegradable bag, a compostable bag and a high-density polyethylene, i.e. conventional plastic bag. Each bag was then exposed to soil, seawater or open air for up to three years.

Here is a break-down of the results:

  • The compostable bag had disappeared within three months in the sea water.
  • The compostable bag was still in-tact after 27 months in the soil, but could not carry anything without breaking.
  • All of the bags tore into fragments after nine months in the open air.
  • Both the biodegradable and plastic bags could still carry weight after three years in soil or seawater; they were able to haul a box of cereal, pasta, crackers, cans of Coke, bananas and oranges.

"This research raises a number of questions about what the public might expect when they see something labelled as biodegradable," study co-author and International Marine Litter Research Unit head Professor Richard Thompson said in a university press release. "We demonstrate here that the materials tested did not present any consistent, reliable and relevant advantage in the context of marine litter."

Thompson told National Geographic that the biodegradable labeling can confuse customers about the most responsible ways to carry shopping and disposing of bags. They might think they are doing the right thing by adding biodegradable bags to recycling bins, when really these bags can interfere with the recycling process.

"If you've got bags with a self-destruct function, the recycler doesn't want that mixed in with other bags," Thompson told National Geographic. "They need known and consistent material. So the issue becomes how do you separate biodegradables from conventional plastics? How is the consumer supposed to know how to dispose of it?"

The study pointed out that successful composting required a particular process and a disposal system organized around it, which the UK currently does not have, according to The Guardian. Vegware, the company that makes the compostable bags used in the study, told The Guardian that their bags were only designed to break down in specific conditions.

"Discarding a product in the environment is still littering, compostable or otherwise. Burying isn't composting. Compostable materials can compost with five key conditions — microbes, oxygen, moisture, warmth and time," a company spokesperson said.

Both the United Nations and the European Union have rejected biodegradable bags as an effective solution to the eight million tons of plastic that end up in the world's oceans each year, National Geographic reported. Thompson is not against biodegradable bags, but thinks it is important that the right bag is matched to the situation in which it is most likely to be disposed of in an environmentally friendly way. For example, biodegradable materials would be advantageous at sports stadiums, where they could be gathered in one place with the rest of the food waste at the end of the game and disposed of in a way that ensures they break down. For grocery shopping by individual consumers, reusing the same bag as many times as possible is a more effective way to reduce waste.

"A bag that can and is reused many times presents a better alternative to degradability," the study concluded, according to National Geographic.

EcoWatch Daily Newsletter

New pine trees grow from the forest floor along the North Fork of the Flathead River on the western boundary of Glacier National Park on Sept. 16, 2019 near West Glacier, Montana. Chip Somodevilla / Getty Images

By Alex Kirby

New forests are an apparently promising way to tackle global heating: the trees absorb carbon dioxide, the main greenhouse gas from human activities. But there's a snag, because permanently lower river flows can be an unintended consequence.

Read More
Household actions lead to changes in collective behavior and are an essential part of social movements. Pixabay / Pexels

By Greg McDermid, Joule A Bergerson, Sheri Madigan

Hidden among all of the troubling environmental headlines from 2019 — and let's face it, there were plenty — was one encouraging sign: the world is waking up to the reality of climate change.

So now what?

Read More
Sponsored
Logging state in the U.S. is seen representing some of the consequences humans will face in the absence of concrete action to stop deforestation, pollution and the climate crisis. Mark Newman / Lonely Planet Images / Getty Images

Talk is cheap, says the acting executive secretary of the United Nations Convention on Biological Diversity, who begged governments around the world to make sure that 2020 is not another year of conferences and empty promises, but instead is the year to take decisive action to stop the mass extinction of wildlife and the destruction of habitat-sustaining ecosystems, as The Guardian reported.

Read More
The people of Kiribati have been under pressure to relocate due to sea level rise. A young woman wades through the salty sea water that flooded her way home on Sept. 29, 2015. Jonas Gratzer / LightRocket via Getty Images

Refugees fleeing the impending effects of the climate crisis cannot be forced to return home, according to a new decision by the United Nations Human Rights Committee, as CNN reported. The new decision could open up a massive wave of legal claims by displaced people around the world.

Read More
The first day of the Strike WEF march on Davos on Jan. 18, 2020 near Davos, Switzerland. The activists want climate justice and think the WEF is for the world's richest and political elite only. Kristian Buus / In Pictures via Getty Images

By Ashutosh Pandey

Teenage climate activist Greta Thunberg is returning to the Swiss ski resort of Davos for the 2020 World Economic Forum with a strong and clear message: put an end to the fossil fuel "madness."

Read More