A plastic bag labelled biodegradable after three years in the marine environment.
Credit: Imogen Napper

Plastic bags that claim to be biodegradable were still intact and able to carry shopping three years after being exposed to the natural environment, a study has found.

The research for the first time tested compostable bags, two forms of biodegradable bag and conventional carrier bags after long-term exposure to the sea, air and earth. None of the bags decomposed fully in all environments.

The compostable bag appears to have fared better than the so-called biodegradable bag. The compostable bag sample had completely disappeared after three months in the marine environment but researchers say more work is needed to establish what the breakdown products are and to consider any potential environmental consequences.

After three years the “biodegradable” bags that had been buried in the soil and the sea were able to carry shopping. The compostable bag was present in the soil 27 months after being buried, but when tested with shopping was unable to hold any weight without tearing.

Researchers from […]