Compostable Plastic: Why It's Not Always the Best Solution

Is compostable plastic really the solution to our plastic problem? Recently, compostable flexible plastic packaging like polylactic acid (PLA) structures have entered the marketplace. Despite its promise of breaking down in industrial composting facilities, North America doesn’t have the infrastructure available to compost this type of packaging, and these bags don’t break down in your backyard compost.

Two reasons facilities don’t accept compostable plastics:

1. Higher requirements for composting facilities.
Compostable flexible plastic packaging requires high temperatures and specific moisture levels to break down properly. Across North America, municipal composting facilities are not equipped to handle these conditions, or the conditions are vastly different from the majority of composting production, resulting in a need for a resource-restrictive separate stream to make sure this packaging will break down as intended.

2. Lack of reliable regulations around labeling and claims. With a similar look and feel to standard plastic, these bags are often confused with traditional plastic packaging, which can lead to contamination in the recycling stream. Presently, there are no regulations on what can be labelled “compostable”, or how to label these products to reliably tell them apart. If traditional plastic packaging ends up in composting facilities, the entire composting stream will be contaminated. To protect against the risk of environmental pollution, facilities do not accept any flexible compostable plastics.

Compost beside compostable packaging
green bin for compost

What happens if a composting facility receives flexible compostable packaging, or if it goes to the green bin?

In this case, the bags will be filtered out and taken to the landfill. Unfortunately, compostable packaging requires light and moisture to break down into organic by-products, which isn’t available in landfills. Because of this, the compostable packaging won’t break down as intended and can produce greenhouse gases.

Ultimately, while compostable packaging may seem like a promising solution, the reality is that these materials are not as environmentally friendly as they may appear. There are options for monolayer recyclable plastic plastics, but it can be hard to get away from traditional plastic structures until these issues are addressed.

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