<http://schema.org/about>
"To qualify as biodegradable, plastic must be scientifically proven to break down completely within a short time, but even plastic certified as biodegradable may"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/lifestyle/responsible-living/stories/biodegradable-plastic-what-you-need-to-know>