“Biodegradable” and “compostable” are terms that pop up frequently in our search to make our day to day purchases more sustainable, but what do they actually mean and what is the difference between the two? That’s exactly the question we’re tackling today. 

Let’s start with “biodegradable.” The term refers to anything that can be broken down by microorganisms, such as bacteria and fungi. Biodegradation is complete when a material has been reassimilated into the natural environment and can happen with or without oxygen. Why is the term a little misleading? Well, vegetable scraps, as you would imagine, are biodegradable and break down in just a few days. On the other hand, plastic is also technically biodegradable, although it takes more than 500 years for it to do so. 

This is why the time to biodegrade is a critical factor when it comes to biodegradable items. For some context, paper takes about two to five months to biodegrade, a cotton t-shirt takes six months, and tree leaves take a year. 

The Federal Trade Commission and third-party certifiers are working to standardize “biodegradable” labeling, but if you’re unsure, you can always ask the company about the breakdown time and conditions of their items. 

“Compostable” items refer to those which can decompose only in specific, man-made conditions. Essentially, they require human intervention to fully biodegrade. The composting process involves breakdown by natural organisms, fueled by water, oxygen, and organic matter inputs from humans.

Composting can be divided into residential and commercial categories. Your residential composting takes food scraps and natural organisms to break down waste but doesn’t generate enough heat to break down meat or dairy. Commercial composting on the other hand screens and sorts materials with specific oxygen and moisture conditions for more heavy-duty breakdowns. This is why items like “compostable” plates can’t be put in your backyard compost bin. This is also why it’s important to check with your local waste disposal sites because most cities don’t actually have commercial composting facilities so that “compostable” plate you just used is heading to the landfill anyway. 

If you thought that compostable items were more environmentally friendly than their biodegradable counterparts, you’re not alone. Unfortunately, the rise of residential composting and societal understanding of the term has led many companies to take advantage of this misperception to greenwash their products. And the truth is “compostable” isn’t always bad. Many plant-based plastics, also known as bioplastics, are a better option in most cases than traditional plastics, especially if your city has a bioplastic composting facility. 

So what’s the takeaway? While most biodegradable and compostable items have good intentions, it’s important to remember that these products are not necessarily as environmentally-friendly as they appear. The bottom line is that reusable goods are always preferable to single-use ones, and it’s critical to do background research on these “green” products before you embrace them.