Biodegradable vs. Compostable: What's the difference?

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Whether you’re a business looking to offer more environmentally-friendly packaging—or a consumer looking for an alternative to plastic products—the green landscape can be a difficult one to navigate. Vague and misleading claims are common in this space—and these various forms of “greenwashing” make it incredibly difficult to identify optimal product options.

Take the terms “biodegradable” and “compostable”, for instance. These two descriptors are often used interchangeably—and to the untrained eye, they appear to mean the same thing. In reality, however, one is just another form of greenwashing—while the other comes with a few caveats as well.

Here, we’ll bust some myths around compostable and biodegradable products. Specifically, we’ll answer:

  • What’s the difference between compostable and biodegradable?
  • How can you tell if a product is truly compostable?
  • Are all compostable materials really compostable?
  • Are compostable products eco-friendly?
  • What are some other common greenwashing terms?

What’s the difference between compostable and biodegradable?

On the surface, compostable and biodegradable products have a lot in common in that they both break down in the natural environment.

The key difference is that the term “biodegradable” refers to anything that will break down in the natural environment over time. There’s no time limit for biodegradation—and there are no rules around how small the broken-down particles need to be, or whether they can leave behind toxic residues. Under this vague definition, therefore, everything is technically biodegradable—even plastic, which can take hundreds of years to break down into microplastics that ultimately pollute our soil.

The term “compostable”, on the other hand, is a regulated term. If a product is deemed “certified compostable”, it meets certain regulatory standards in how it biodegrades. Specifically, these products break down completely into water, carbon dioxide and biomass. They do so within 90 days, and they leave no harmful residue.

Because of the extra steps required to earn a compostable label, most compostable products can be disposed of in a compost bin and transform into nutrient-rich compost at a local industrial compost facility. That said, not all compostable products are created equal—and not all of them can be thrown into just any compost bin.

How can you tell if a product is truly compostable?

Because the term “compostable” is regulated, companies that use the term on their products must have the products tested and certified by third parties to prove that they meet certain parameters. Once certified, the product will be able to include specific marks. Marks to look out for include:

BPI Certified Compostable

The Biodegradable Products Institute (BPI) is “North America’s leading authority on compostable products and packaging”. The organization’s certification program offers third-party verification of ASTM standards for compostable products.

ASTM D6400 is a globally-recognized mark that outlines the conditions and timeframe within which a compostable product must degrade. This testing is done in a laboratory environment, so the results are as consistent as possible in between tests. A product passes if it biodegrades within 90 days, doesn’t leave behind any harmful residue, and if the resulting compost is not harmful to plant life.

Compost Manufacturing Alliance (CMA) Approved

While BPI Certification demonstrates that a product meets composting standards in a lab setting, it doesn’t account for the variability in real-life environments. This is where CMA approval comes in

CMA conducts “field disintegration testing”—which essentially involves testing BPI Certified compostable materials in a commercial composting facility to make sure they disintegrate within the allotted timeframe. Products with a CMA logo are proven to disintegrate in a commercial composting facility, as predicted, without contaminating the compost.

The optimal compostable products will be both BPI Certified and CMA Approved.

Are all compostable materials really compostable?

This seems like a bit of a silly question—but the answer isn’t as straightforward as you’d think. Compostable products are made of a range of materials. For instance, compostable paper trays are made of natural fibers such as bamboo and sugar cane—while compostable liners are made of resins comprised of both organic sources as well as petroleum products (which make the bags leak-resistant).

Different types of compostable materials require different conditions to fully decompose within the allotted 90-day time span. In many cases, commercial composting facilities are the only facilities powerful enough to create the amount of heat necessary to adequately break them down—and even then, the equipment in these facilities differ from municipality to municipality.

Because of this, unless they’re marked as “certified home compostable” most of these compostable products will not break down in a home compost bin—and even those that are BPI Certified may not break down in your local commercial composting facility. To be sure, it’s best to contact your local composting facility’s website (or app) to understand what is, or isn’t, accepted. When in doubt, it’s best to throw a product out—otherwise you could end up contaminating the entire compost batch.

Are compostable products “eco-friendly”?

When certified compostable products find their way to the compost bin—and are composted in the right environment—they will biodegrade completely into nutrient-rich compost while emitting negligible amounts of CO2. But we’d avoid calling them eco-friendly.

The term “eco-friendly” is incredibly vague—it essentially means that a product is “not environmentally harmful”. But given that everything human beings make has some sort of environmental impact—either in the way these things are produced, used, or disposed of—there’s really no such thing as an eco-friendly product.

According to the FTC’s Green Guides, if a company chooses to use the term eco-friendly on a product, it must explain why the product is environmentally responsible. In the case of certified compostable products, they offer an alternative to single-use plastics, help reduce the amount of waste destined for landfill and encourage composting behaviour. That said, these benefits can only be realized if these products are disposed of in a green bin—which means there needs to be enough green bins, and a nearby composting facility capable of accepting these products. This is not the case in many areas in North America.

Common greenwashing terms

While many companies use the terms “biodegradable” and “eco-friendly” to greenwash their products, these are by no means the only misleading adjectives used in this space. Below are a few others that you should be wary of:

  • Oxo-degradable: If a product is oxo-degradable it’s essentially made from standard plastic, but includes an additive that attracts bacteria to ultimately speed up the degrading process. While oxo-degradable products are biodegradable, they don’t break down like a compostable product would. Rather, they degrade into smaller and smaller pieces, eventually leaving microplastics behind.
  • Plant-based: While many compostable products are plant-based, their vegetative origins don’t necessarily make them better for the environment. For instance, some compostable liners may tout a higher percentage of plant-based materials in their resins, but this simply makes the products cheaper to produce while compromising their strength (and does nothing positive for the environment).
  • 100% biodegradable: Products that are 100% biodegradable will completely break down in the natural environment. But, seeing as every material on earth will ultimately break down into smaller pieces (given enough time), this term doesn’t really mean anything.  
  • Sustainable: Again, this term doesn’t mean much on its own. Is the product sourced from renewable sources? Are materials ethically sourced? Is it somehow better for the planet than comparable products? Without further details, it’s simply another form of greenwashing.

Don’t navigate this terrain alone

As the world strives to reduce its reliance on fossil fuels, the push to reduce—and, ideally, eliminate—single-use plastic, plastic products and plastic packaging is going to grow stronger. Certified compostable products are an excellent option to bridge the gap, as they provide alternatives to plastic products we are currently accustomed to.

For instance, in the food services space, cling wrap is often used when packaging certain products—and in some cases, it’s necessary to avoid contamination. In this instance, compostable cling wrap could dramatically reduce the amount of plastic destined for landfill, provided there were proper composting resources in place—and people were educated on the importance of putting such products in their green bin.

In a similar vein, composting food waste in a commercial composting facility is substantially better than sending it to landfill, where it decomposes and releases methane gas. That said, composting can be a messy business—and many individuals may not want to store food waste in their homes due to the “ick” factor. Compostable liners can incentivize them to participate in composting programs by making the process significantly cleaner and easier.

If you’re interested in exploring compostable options for your organization, EcoSafe Zero Waste offers a host of products for the food services industry, as well as curbside and multi-residential composting programs. To learn more about our products, and their environmental impacts, contact us.

Food loss and waste occur at each stage of the supply chain. The biggest proportion (about 37%) happens in the home.

ReFED, 2021