Researchers at the University of Plymouth in the UK examined the degradation of five plastic bag materials found in stores to understand how well they degrade.
Led by Richard Thompson, a marine biologist who studies plastic waste, the researchers examined the plastic bags by burying them in dirt, submerging them in water and exposing them to outdoor air as if they were litter.
The study found that bags in soil or marine environments were still able to hold a full load of groceries after being exposed to the natural environment for three years.
The researchers concluded that none of the five plastic materials, including the compostable bags, reliably deteriorated enough over the three years to give them any environmental advantages over conventional bags.
The study highlights how consumers can be confused by the term “biodegradable,” expecting that the bags will disappear once thrown away.
The researchers emphasize the need for stricter standards for biodegradable materials.