Not all “biodegradable” plastics are created equal

Going green is one of the fastest growing consumer trends today. Good news for the environment with eco-friendly consumers putting pressure on brands to create sustainable products. But extremely damaging when companies simply jump on the band wagon by using misleading labelling and packaging.

Buyer beware

Be wary of any claim of being “Biodegradable” if there are no details on where it will biodegrade and how it will biodegrade. Ask yourself “where is it going to be disposed of for it to biodegrade? In a landfill? In a home compost? Or in a commercial composting facility?” 

And if it claims to be “recyclable”, ask yourself if it can be mainstream recycled – meaning it can go into your household recycle bin for council collection. If the answer is NO, then don’t buy it.

Know what the labels mean

With no national requirement for product labelling, consumers are easy targets for misinformation. Let education be your best defence and learn what the labels mean.

Bioplastics are made from plant-based materials. Only a small portion of bioplastics are biodegradable, most of which require a municipal or commercial compost facility to biodegrade and they cannot be recycled.

Compostable plastics refer to “biodegradable” plastics made from plant-based materials like corn and wheat starch which will only biodegrade if composted in a municipal or commercial compost facility. PLA or Polylactide for example is a compostable plastic. Unfortunately, there are not many composting facilities available or accessible in Australia. In fact, there is no existing infrastructure to separate compostable plastics from other waste or to transport them to such facilities, resulting in them going to landfill. “Compostable plastic” will not biodegrade in landfill as the environment there is too cool. They also cannot be recycled.

Degradable plastics have nothing to do with biodegradation and microorganisms. “Degradable” or “oxo-degradable” plastics use a metallic additive that sets off a slow chemical reaction and over 12-24 months which causes the plastic to fragment into little pieces. So, instead of one piece of plastic we end up with hundreds or thousands of little pieces of plastic which may not be visible, but create a worse result for the environment, particularly when marine animals easily consume these fragments. “Degradable” plastics cannot be composted or recycled.

Landfill biodegradable plastics incorporate an organic food source additive in the plastic at the time of manufacture. When disposed to a landfill they attract naturally occurring microbes that exist in there. The microbes seek out the food and in the process the enzymes they secrete break down the long polymer molecules where they can be digested too. The resulting products of the biodegradation are a biogas and a biomass (humus). There is no plastic residue left or any toxic constituents. “Landfill biodegradable” plastics can be recycled. They can also be composted in a municipal or commercial compost facility. Their results are verified by various ASTM testing methods.

NOTE: No plastic is good in the ocean. There are no microbes present there to biodegrade the material away.

By Dr Ross Headifen, educator of responsible plastic use and co-founder of Biogone.