PENCINTA ALAM JANUARY 2011
GREEN LIVING COLUMN
BIODEGRADABLE PLASTIC BAGS
Q: WHAT ARE BIODEGRADABLE PLASTIC BAGS?
There are generally two groups of bio-degradable plastic. Hydro-biodegradable plastics are made from starch-based polymers (derived from tapioca, corn, potato or wheat) while oxo-biodegradable plastics are conventional petroleum-based products with some additives that hasten degradation. When exposed to the right conditions (heat, oxygen and moisture), both will undergo chemical degradation, resulting in a reduce molecular weights. The smaller molecules are then amenable to biodegradation by micro-organisms, which convert the materials to carbon dioxide and water. Some polymers require UV light in order to break (photodegradable polymer) while others need aerobic conditions (compostable polymer).
Q: ARE BIODEGRADABLE PLASTIC BAGS REALLY BETTER FOR THE ENVIRONMENT?
Proponents of biodegradable plastics argue that certified biodegradable plastics combine the utility of plastics (lightweight, resistance, waterproof, relative low cost) with the ability to completely and fully biodegrade in a compost facility, therefore eliminating the problems caused by conventional plastic bags (i.e. high cost of recovering and recycling plastic bags, high wastage, endangerment of wildlife and birds, clogging of waterways and landfills).
There are conflicting views as to the environmental benefits of biodegradable plastic bags. Some reports say the production and disposal of biodegradable plastics use less energy and water, generate less greenhouse gases, and produce less waste. But there are also studies which say otherwise.
Then there are criticisms that most so-called biodegradable plastics only degrade (changes in chemical structure and loss in mechanical properties, resulting in the plastic breaking down into small fragments) and do not biodegrade (break down and be consumed by micro-organisms).
Whatever the argument, it is important for us to remember that biodegradable plastics are not the solution to waste management problems. Biodegradable plastics may even create the idea that it is alright for us to generate and discard waste without due consideration, as long as the waste is biodegradable. As with everyone who is concerned about our natural environment, we need to use less disposable packaging and get into the habit of bringing our own reusable containers and bags.
Q: HOW DO I DETECT GREENWASHING WHEN IT COMES TO BIODEGRADABLE PLASTIC BAGS?
There are various kinds of biodegradable plastic bags in the market, but most are not environmentally-friendly. Companies are mostly claiming biodegradability, and unfortunately the greenwashing has taken over the science. Only bags (or any type of biodegradable plastic, for that matter) that conform to compostability standards ASTM D6400 or EN 13432 are truly biodegradable and can be trusted. Oxo-degradable, oxo-biodegradable, oxy-degradable, oxy-biodegradable, and degradable plastic (bags) are not environmentally friendly. They are merely plastic with a chemical additive.
Check the vendor’s claims about the biodegradable plastic bags. If the bags contain plastic (or technically called Polyethylene), these are not biodegradable bags, but rather plastic mixed with a chemical additive that in a short time interval breaks the plastic molecular ties and thus the plastic disintegrates.
Check if the vendor has certification for the material. The only acceptable certification should be ASTM D6400 and/or DIN EN13432.
If the price of the biodegradable plastic bags is very close to that of plastic bags, you are probably not buying biodegradable but rather the plastic with the additive mentioned above.
** Information compiled from http://thestar.com.my/lifestyle/story.asp?file=/2010/12/7/lifefocus/7548373&sec=lifefocus and http://www.biodegradableplasticbags.org/)