colin williamson explains his plea to stop using biodegradable plastic &lsquoplease don&rsquot use them, don&rsquot recycle them and don&rsquot tell me how wonderful they are.&rsquoin the 21st century drive for sustainability, the concept of biodegradable plastics seems fantastic. the iconic manmade product reverting to nature seems too good to be true. and, of course, like anything that seems too good to be true, it probably is.biodegradable plastics do exist, of course, made from agricultural materials or made by modifying conventional petrochemical based materials.