You want to shop sustainably. When it comes time to get rid of something, you want to do that sustainably, too. So you notice some products that claim biodegradable packaging, some products labeled “biodegradable” and others labeled “compostable.” What do these labels mean? And how can that guide your choices?

Sometimes, you’ll see or hear biodegradable and compostable used interchangeably. They don’t mean the same thing. Using them as if they did adds an unnecessary level of confusion. Some people misuse these terms because they don’t clearly understand the distinction. Others, alas, seem to jumble them together to mislead.

Everything compostable is biodegradable. Not everything biodegradable is compostable. The distinction might not seem important, except that some of the products or packaging are made of plastic and labeled biodegradable. So we can narrow the question: what are we supposed to do with biodegradable plastic packaging?

The meaning of biodegradable

Biodegradable means that living organisms—bacteria and fungi—will break something down into products that exist in nature. Heat, sunlight, and water also break things down but don’t count as biodegradation.

Some bacteria have recently been found to degrade some kinds of plastic. Mostly, though, plastics and metals are not biodegradable.

Different substances break down at different rates. For example:

• Vegetable scraps: 5 days to a month
• Paper: 2-5 months
• A cotton garment: 6 months
• Tree leaves: maybe a year.
• Twigs, branches, or logs from fallen trees: a very long time

These figures assume no human intervention in the process. The figure for vegetable scraps also assumes that rabbits or other critters don’t eat them first.

The meaning of compostable

Industrial composting, turned aerated pile method / Green Mountain Technologies

Compostable means something that biodegrades with human intervention. We deliberately combine organic matter, moisture, and oxygen to speed up the process. There are two major kinds of composting: home composting and industrial composting. Either municipalities or commercial companies can perform industrial composting.

Home composting requires no equipment or expertise beyond what most people can provide. Tools such as compost bins or tumblers exist but are not strictly necessary. People can simply pile compostables on the ground in some suitable spot and occasionally turn them with a pitchfork.

The interior of the pile will heat up to something more than human body temperature. The heat creates a perfect environment for microbes and earthworms to feast on whatever is in the pile.

Over time, they’ll eat the organic material and excrete their wastes. The technical term for the contents of the resulting compost is humus. But we can think of it as worm poop. It’s a great garden amendment and soil conditioner.

Industrial composting requires special equipment that, among other things, achieve much higher temperatures. So it can deal with meat products and other substances not suitable for home composting.

Equipment includes grinders and chippers to chop, say, those tree branches into much smaller pieces and provide more surface area for the bacteria to work on. It may use very large piles, comparable to a home compost pile but turned with bulldozers instead of pitchforks. Or it may use vessels comparable to a home tumbler.

Bioplastics, biodegradable packaging, and compostable plastic

Bioplastic packaging blister made from cellulose acetate

Man-made biodegradable packaging and products usually mean biodegradable plastic. Bioplastics are made from plant material instead of petroleum. Some can even be made from various agricultural wastes.

Making them emits less greenhouse gases than conventional plastics. Therefore, they may have significant environmental advantages. There are too many variables to make a simple statement.

But they are not recyclable. Not all of them are even biodegradable. They do not biodegrade in home compost piles, landfills, or if they get into the ocean.

Bioplastics break down at temperatures of about 120 F°. That’s about 20° hotter than the hottest temperatures a landfill ever gets to. They have about the same environmental impact there as any regular plastic.

They do break down in industrial composting facilities, but not all industrial composting facilities accept them. The general public knows little about industrial composting. Both more recycling/composting infrastructure and more public education are required before bioplastic can live up to its promise.

What happens to bioplastics when you’re through with them?

The FTC defines compostable packaging as anything that will break down at about the same rate as anything else on a home compost pile. Biodegradable packaging, on the other hand, only means that it will break down in the environment into compounds found in nature in a reasonable time.

In other words, it is misleading to label anything as biodegradable if it decomposes in lab tests but not in real-world conditions. And real-world conditions normally mean in landfills, where hardly anything decomposes in reasonable time.

More and more companies are marketing bioplastic utensils such as plates, cups, straws, or sporks as compostable. But unless they are specifically labeled for home composting, they’ll only decompose in industrial composting facilities.

And they are not recyclable. Mixing bioplastics with any plastic accepted in ordinary recycling programs will simply contaminate whatever they’re mixed with.

If you actually compost at home, or if you have access to community composting, buy compostable products.  If you have access to an industrial composting facility, accept biodegradable packaging. Otherwise, the biodegradable vs compostable distinction hardly matters. You can’t do anything with either of them except put them in the trash.

Sources:

Biodegradable vs. compostable: what’s the difference? / Kiah Treece, Treehugger. May 12, 2021
The truth about biodegradable plastic packaging / Eventige Media Group
What’s the difference? Biodegradable vs. compostable / Heather Blackmore, Bob Vila
What’s the difference between recyclable, biodegradable and compostable packaging? / Edyta Dean, Macfarlane Packaging. January 16, 2020