Reading the Label: “Sustainable” Plastics

We come across the question often, is “biodegradable” plastic really plastic?

The short answer is, yes.

The long answer is, well, complicated. 

Marketers have caught on to the plastic-free movement, but the definitions of labels that line the shelves are often murky. Here are some common terms you might see on shelves in Canada, and what they really mean.


Plastics labelled as biodegradable can change their chemical structure over time, but there is no standard or requirement for how long this could take. It could break down in a month – or 10,000 years – and it can still be labeled “biodegradable”. There is also no standard for what it breaks down to, so some may break down into small pieces of plastic that never truly disappear.

Grade: F. Biodegradable plastics should go to landfill.

“Eco” or “Natural”

Run away from these products if there are no other certifications or labels. Everything is natural – including rocks, arsenic, and petroleum.

Grade: F.* Plastics labeled ‘eco’ or ‘natural’ should go to landfill, unless there are other labels such as certified compostable that you understand.

These plastic cups may say “eco,” but they didn’t decompose on the beach they were found.
Photo by Brian Yurasits.


These plastics have additives that assist them in breaking down faster. However, the European Bioplastics organization says a more accurate term is oxo-fragmentation, since the plastics break down into smaller pieces of plastic that remain in the environment. In 2017, 150 organizations worldwide called for the ban of oxo-degradable plastics.

Grade: F. Oxo-degradable plastics should go to landfill.


Certified compostable plastics have to abide by a set of standards where they can break down at the same rate as other compostable materials. In Canada, for a bag to be labeled compostable, it must disintegrate by 90% within 84 days of the composting process, and biodegrade by 90% within 180 days of the composting process, as well as have no harmful effects on plant life. 

Every city has different composting processes and therefore will have different rules. In Calgary, only certified compostable plastic bags are accepted and the product must be certified by BPI or BNQ to be accepted in the City’s compost system. Something to keep in mind is that when compostable bags do break down, they simply turn into mainly carbon dioxide and water. Veggie peelings and garden waste add nutrients to compost, but compostable plastics don’t.

Grade: B. Certified compostable plastics can go in the municipal compost if your city or town accepts it.

The only thing that would get an “A” grade in our minds is to not use plastic bags at all. When you use compostable plastics, dispose of it in a municipal compost facility that accepts it. It’s important to remember, all of these plastics take resources to manufacture, and none of them add value to compost.