The idea of a “biodegradable” plastic suggests a material that would degrade to little or nothing over a period of time, posing less of a hazard to wildlife and the environment. This is the sort of claim often made by plastic manufacturers, yet recent research has revealed supposedly biodegradable plastic bags still intact after three years spent either at sea or buried underground. So un-degraded were these bags that they were still able to hold more than two kilos of shopping.
The study’s authors, Imogen Napper and Richard Thompson at the University of Plymouth, tested compostable, biodegradable, oxo-biodegradable, and conventional polythene plastic bags in three different natural environments: buried in the ground, outdoors exposed to air and sunlight, and submerged in the sea. Not one of the bags broke down completely in all of the environments tested. In particular, the biodegradable bag survived in soil and sea almost unscathed.