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July 16, 2021

Bioplastics: What they are and why they aren’t a solution to plastic pollution

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Topics: Plastics



Bioplastics, including so-called compostable plastics, are showing up in grocery aisles, restaurants and even office supply stores. But are these products actually a solution to the plastic pollution crisis? The short answer is no.

The term bioplastics is a broad term to describe bio-based, biodegradable, and compostable plastics. But these terms don’t all mean the same thing.

For example, biodegradability isn’t exclusive to bio-based plastics, and not all biodegradable plastics are compostable. And very few compostable plastics are compostable in the environment, or in your backyard composter.

Huh? Don’t worry, by the end of this blog you’ll understand the distinctions and limitations of these categories of bioplastics and, most importantly, why none of them are solutions to the plastic pollution crisis.

Bio-based plastics

Bio-based plastics can be made entirely from renewable biomass — like sugarcane and corn — or from a combination of renewable biomass and fossil fuel (oil and gas) sources. However, even if they are made entirely from corn, bio-based plastics don’t always biodegrade quickly into organic materials at their end-of-life. For example, Coca-Cola’s Plant Bottle is made from up to 30 per cent plant-based material, but the plastic is chemically identical to traditional plastic – meaning it isn’t any more biodegradable than a regular pop or water bottle.

Biodegradable plastics

Biodegradability is not exclusive to bio-based plastics. Traditional plastics can biodegrade too. In fact, nearly everything will eventually biodegrade given enough time (in the case of plastic though it is presumed to take hundreds, if not thousands of years.) So, labelling something as biodegradable, without any additional information about how long it will take or what specific conditions are needed for it to do so, is at best meaningless and at worst greenwashing.

Compostable plastics

Compostable plastics are designed to break down into natural substances (compost, water and carbon dioxide) in an established timeframe and under specific conditions – humidity level, oxygen availability and high temperatures, for example. Basically, they are designed to only breakdown in industrial composting facilities.

Compostable plastics don’t breakdown in backyard composters, landfills or the environment

Because compostable plastics are designed to biodegrade under very specific conditions, which are not met on the side of the street or in most landfills – and definitely not in the middle of the ocean – compostable plastics will likely persist for just as long as traditional plastics in the environment. That means, just like traditional plastics, compostable plastics are a threat to wildlife that become entangled in or ingest them.

Can I put compostable plastics in my organic waste bin?

It’s important to remember that a lot of municipalities do not offer curbside composting programs. And many that do, including Toronto and Vancouver, do not accept compostable plastics in their organic waste bins.

Why not? Compostable plastics do not always decompose at the same rate or temperature as other organic materials, like household food waste, yard trimmings and soiled paper products. That means slower waste processing times or additional sorting and reprocessing stages, which cost time and money.

Additionally, compostable plastics are designed to look and feel like traditional plastics, and in typical composting facilities, there is a sorting step specifically to remove non-compostable contaminants, like traditional plastic, before the composting begins. Because compostable plastics are often indistinguishable from traditional plastics, they are removed by machines or people working in these facilities and in turn sent to landfill.

Can I put compostable plastics in my recycling bin?

Absolutely not! Another downside to looking and feeling like traditional plastics is that so-called compostable plastics can mistakenly be sent to recycling facilities with other single-use plastics, where they contaminate potentially valuable recyclable materials and lower the quality of recycled materials.

So, please, please, please do not dispose of your compostable plastic smoothie cup in the recycling bin. If you’re in doubt, throw it out.

TL;DR: We can’t compost our way out of the plastic pollution crisis.

Compostable plastics are just another form of single-use plastic. And while there may be some advantages, like reduced reliance on fossil fuels, there are a lot of downsides as well.

The biggest issue with compostable plastics is that they do not rapidly degrade where it matters most – in the environment, including our oceans. And that means compostable or not, plastic continues to starve, entangle and kill wildlife. Tragically, the very idea of compostable plastic might feel like a free-pass to keep choosing single-use when we really need to reduce plastic use overall.

That is why this Plastic Free July we are calling on the Canadian Government to finalize a strong ban on single-use plastics – including so-called compostable plastics. Add your voice today.