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.