It turns out that these "biodegradable" plastic shopping bags may not be as good for the environment as the first thought.
First class study, published in the journal Environmental Science and Technology found biodegradable bags were still able to carry shopping after immersion in soil and water for three years.
For this study, researchers spent three years testing on five different types of shopping bags currently offered by popular supermarkets – biodegradable, oxo-biodegradable, compostable, and high density polyethylene.
“These materials were exposed in three natural environments; in the open air, buried in the soil and immersed in seawater, as well as under controlled laboratory conditions, ”the report explained.
The bags were checked at regular intervals with a monitored degree of deterioration.
Each of the bags, after exposure to air for nine months, fell into fragments, but three materials – including biodegradable bags – were buried in soil or sea for more than three years.
In fact, bags not only remained intact, but could still carry nearly 2 kilograms of food.
Compostable bags were the most environmentally friendly when they stayed in the sea, divided into larger pieces after three months in the marine environment.
However, they could still be found in the soil after 27 months – although it was unable to keep any foods.
Researchers questioned whether some of these products should be marketed along with statements that they can be "recycled back to the wild" or "plant alternatives to plastics".
The study also highlighted how the term "biodegradable" can confuse consumers who believe that a bag simply disappears when it is fired. However, researchers insist that this is not an argument against the development of biodegradable or compostable materials.
"Our results together have shown that none of the bags could rely on significant deterioration in all environments in three years," the report said.
"It is therefore unclear whether oxo-biodegradable or biodegradable formulations provide sufficiently advanced degrees of deterioration that are beneficial in relation to marine waste reduction compared to conventional sachets".
Research comes after Woolworths, Coles and other retailers have banned disposable plastic bags in July last year.
The National Retail Association (NRA) estimates that 1.5 billion disposable plastic bags have been removed in the first three months after the ban was imposed.
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