The notions about biodegradable shopping bags may not be correct in the real sense, a new study of the University of Plymouth suggests. The biodegradable shopping bags were earlier thought to have an advantage over conventional plastic bags that they do not last long in the natural environment, but the fact is something else.
According to the study published in Environmental Science and Technology on Sunday bags that billed as biodegradable, even after being buried in soil or submerged in the sea for three years could carry groceries around five pounds, 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.
As per The Guardian, five types of bags available throughout the UK were compared by the researchers. They are two oxo-biodegradable bags, a compostable bag, a biodegradable bag, and a high-density polyethylene or conventional plastic bag. Each type of bag was exposed to soil, open air or sea water for three years.
The results are as follows:
- There was no sign of the compostable bag in the sea water within three months.
- Even after 27 months the compostable bag was found intact in the soil but failed to carry anything without breaking.
- After nine months in the open air, all type of bags turned to fragments.
- Both the biodegradable and plastic bags buried in soil or seawater for three years were able to carry the weight of a box of cereal, bananas and oranges, pasta, cans of Coke and crackers.
“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.”
The biodegradable labeling can confuse customers that they are the most reliable ways when it comes to carrying shopping bags and disposing of them, Thompson told National Geographic. They are dumping biodegradable bags to recycling bins thinking it is the right way to do; however, these bags may not support 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 Guardian reported that the UK currently lacks the infrastructure to carry out the successful composting process and organize a disposal system around it; the study pointed out. As Vegware, the compostable bag producing company that used in the study told The Guardian, their bags were only designed to break down in certain 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.
The United Nations and the European Union both have found an effective solution to the eight million tons of plastic that end up in the oceans of the whole world each year, and that is rejecting biodegradable bags, National Geographic reported.
It is not that Thompson is against the biodegradable bags, but according to him depending on situations, it is vital that the bag to be the right one should get disposed of in an environment-friendly manner. For example, it is better to use biodegradable materials at sports stadiums, where they could be gathered in one place along with the food waste and disposed of at the end of the game in an ensured way that they break down.
However, for grocery shopping, one of the most effective ways to reduce waste is that individual consumers reuse the same bag as many times as possible.
“A bag that can and is reused many times presents a better alternative to degradability,” the study concluded, according to National Geographic.