Biodegradable plastics are not a solution to the problem of ocean litter.
That’s the conclusion of a new United Nations report titled “Biodegradable Plastics and Marine Litter: Misconceptions, Concerns and Impacts on Marine Environments”.
“The adoption of plastic products labelled as ‘biodegradable’ will not bring about a significant decrease either in the quantity of plastic entering the ocean or the risk of physical and chemical impacts on the marine environment, on the balance of current scientific evidence,” states the report authored by Dr. Peter Kershaw, an English scientist who has studied ocean litter for several years.
Complete biodegradation occurs when plastic is broken down to carbon dioxide, methane and water.
“The process is temperature dependent and some plastics labelled as ‘biodegradable’ require the conditions that typically occur in industrial compositing units, with prolonged temperatures of above 50°C, to be completely broken down. Such conditions are rarely if ever met in the marine environment.”
Biodegradable plastics actually create environmental problems because they contaminate recycling streams, according to the report.
My take: Marketers have made inappropriate claims concerning biodegradability of certain plastics for many years. This is a well-documented and fairly written report that lays out the issues clearly. There is a role for biodegradable plastics, such as places that have industrial composters. It appears, based on this report, that typical claims about ocean biodegradability (based on current technology) are not supportable.