Plastic pollution has recently been emerging as one of the world’s most pressing environmental issues, with poor and racialized communities around the world disproportionately affected by the entire lifecycle of oil extraction, plastic production, unsafe recycling, polluted beaches, and plastic landfilling. In light of this, industry has been working hard to produce alternatives to traditional plastics, especially for single use items. Often, this looks like compostable products, which individuals and businesses pay a premium for because they care about the environment. Compostable plastics aren’t a straightforward “win” for the environment, unfortunately. Here we unpack and demystify the terms, what compostable plastics really are, and what the end of their life looks like. Skip to the end if you just need the action steps!

Demystifying the Terms

Whether on store shelves or on your takeout containers, you may have seen products making claims like “biodegradable packaging” or “this plastic is made from plants”. Other claims out there include “oxodegradable”, “compostable”, “fully compostable”, “biobased plastic”, and “bio-PET”. We’ve seen these on everything from straws, cups, plates, and utensils, to garbage bags, general packaging, and coffee pods. These terms all sound pretty green to the consumer, but what you might not know is that they all mean different things! Read on to avoid getting greenwashed. 

Biodegradable

Biodegradable sounds great, but doesn’t mean a whole lot. There is no standard for what this term actually means, so just like products branded “natural”, don’t be pulled in by the term. Biodegradable plastic, whether “bio-based” or otherwise, has a chemical additive that helps to speed up breakdown. By “speed up”, we mean timespans of about a decade, as opposed to dozens or even hundreds of years. Biodegradable plastics are likely to break down into smaller and smaller pieces of plastic, eventually creating those microbeads we all want to avoid – and if they’re buried in a landfill far from light, oxygen, and water, they may not even do that. In the end, they’re still plastic.

Compostable Plastics

In general, an item is compostable if two conditions are met: 1) it is made up entirely of “organic” elements (derived from living organisms) and 2) it will decompose into an organic compound called compost. This compost is used as a soil amendment to improve the soil texture and add nutrients that are beneficial to plants. It can even help soils to act as a more efficient carbon “sink” to remove carbon dioxide from the atmosphere!

According to the Biodegradable Products Institute (BPI), in order for a package to be considered compostable, it must break down within a specific timeframe. Most facilities need materials to break down in 80 days or less. This material must biodegrade at a rate comparable to yard trimmings and food scraps, and they must disintegrate so that no large plastic fragments remain to be screened out. Compostable plastics are made from plants, not fossil fuels, and they should be certified compostable by an organization like BPI. Because they don’t contribute to more unsustainable extraction of non-renewable fossil fuels, and because they can break down in the proper composting facilities, this claim isn’t usually greenwashing. However, there are still issues with compostable plastics. To understand these, first we need to understand the types of compostable plastics.

Types of Compostable Plastics

Polylactic Acid, or PLA, is one of the most common compostable plastics used today. Under the right conditions, it breaks down to carbon dioxide, water, and compost, and does not produce microplastics. Products often made with PLA include clear disposable drinking cups, clamshell containers, compost bags or compostable garbage bags, and plastic cutlery. In theory, you can recycle PLA, but almost no recycling programs accept it. The market to buy it and the facilities to recycle it don’t currently exist.

Two other types of compostable plastic that make up significant portions of the world market are Ecoflex, and various starch based blends. Ecoflex is a biodegradable polyester that is certified compostable and made by the company BASF. Starch blends might be familiar to you in the form of grocery bags stating that they are made from cornstarch, though they’re used in many other products as well.

Problems with Compostable Plastics

1. Compostable products are not designed for home composting systems
Compostable products are tested for use in large-scale, commercial composting systems. These get much hotter, and are more carefully managed, than a typical backyard compost heap. For a compostable plastic to actually compost, it needs high heat and large amounts of oxygen, or it won’t break down.

2. Lack of infrastructure: No access to composting
Many municipalities, especially smaller ones, do not have easy access to commercial composting that can handle compostable plastics. This means that that compostable dog-poo bag you paid extra for? It’s still going in the landfill, where it will slowly break down, producing methane gas (a greenhouse gas 25x more potent than carbon dioxide) in the process. In Winnipeg, Brady Landfill is Manitoba’s second-largest point-source greenhouse gas emitter, largely due to organics (including compostable plastics).

3. Lack of infrastructure: Composting systems can’t handle compostable plastics
Many places that do have commercial composting facilities still struggle to accept compostable plastics. There’s a number of reasons for this, depending on the facility, but they include:

• • Compostable plastics can look the same as non-compostable plastics, making it difficult to sort out what is a contaminant, and leading to contamination of the finished compost with plastics
  • Open composting facilities may find compostable bags blow away, rather than composting
  • Facilities designed to deal with leaf and yard waste exclusively are not set up for compostable plastics
  • Composting facilities have a careful “recipe” to produce finished compost, and different feedstocks coming in unexpected quantities and ratios can make this challenging. Current “recipes” need to be redesigned to handle compostable plastics
  • Compostable plastics vary dramatically: a filmy plastic bag and a chunky plastic fork compost at very different rates, for example. Compostable cutlery and clamshells may need to be pre-shredded before being added to a compost pile.
  • Compostable plastics may affect certification (and therefore saleability and value) of finished compost, depending on local regulations

Just like recycling, just because something can be composted, doesn’t mean it is composted.

The Recycling Council of Ontario’s Plastic Action Centre has a great infographic about bioplastics if you’re a visual learner.

Now What?

As an individual citizen, the challenges of how to make the best, lowest-waste, lowest-impact choices can be overwhelming. There is usually no straightforward right answer – and that’s the case with compostable plastics. That said, here are a few rules of thumb you can use going forward, and some actions you can take to make a difference for good!

1. When in doubt, first “refuse” and “reduce”. Do you need a compost bag, or can you just rinse your bucket after dumping it in your backyard bin? Can you use a pooper scooper to grab dog poo and put it in a pet waste digester, instead of grabbing it with a plastic (or compostable plastic) baggie?

2. If you can’t reduce, try to reuse – or choose a reusable option. Eating takeout? A metal fork from the thrift store that you keep wrapped in a napkin in your purse or backpack has a much lower impact than a compostable fork.

3. Stuck with a single-use item? Here’s a few questions you can ask yourself to figure out your personal best option:

• • What will happen to this when I’m done with it? (If it’s compostable, are there compost facilities available? If it’s recyclable, is it accepted in the local system? Will you be willing to take it with you to properly dispose of it if there are no waste sorting bins close at hand?)
  • If it’s going to be thrown out either way, what is it made out of? (Is it made from a renewable resource? Compostable plastics often are. This is a step up from a conventional plastic that is typically made from a nonrenewable resource)
  • What option has the least amount of waste associated with it? (A fast food wrap in a single sheet of paper has a lot less waste than a fast food salad in a clamshell bowl of black, non-recyclable plastic
  • Who can I constructively express my frustration to?
    Ok, technically this won’t help you make a better choice in the moment, but citizen voices help change governmental regulations, and customer voices help shift business practices. Can you fill out a comment card? Mention something to a manager? Write a letter to a business? Meet with your government representative? Sign a petition? Attend a protest? Write a letter to the editor? Boycott particularly problematic examples of waste? Find the method of agitating for change that suits you best, and give it a go!