Dear Dot: What’s the Deal with Compostable and Biodegradable Plastics?



Dear Dot,

What’s the deal with compostable and biodegradable plastics? Are they really compostable? Can I toss these plastics in my recycle bin? Or is there another way I should be disposing of them? Also, why is this all so damn confusing?


The Short Answer: The most environmentally sustainable choice is the product that will be reused over and over again. Which means, Lou, that Dot can deliver a simple response: Avoid one-and-done products even when they’re promising biodegradability and compostability. 

My dear, confused (join the club!) Lou,

Oh, that I could offer a simple response to your final question. As a reader recently wrote to us in gratitude for Bluedot’s BuyBetter Marketplace newsletter, “doing the right thing for the planet shouldn’t be so confusing.” 

Alas, it falls on us to un-muddle ourselves. 

First off, it is my deep displeasure to point out to you and all readers that recycling, despite our society’s unprecedented enthusiasm for it, has been largely a failure. There are a couple of reasons for this. 

First, shockingly, only nine percent of plastics put into the recycling stream actually get recycled. I know. Let’s both slow down our breathing, Lou. You okay? Cause there’s more.

Second, a considerable amount of the plastic that does get recycled produces infinite amounts of microplastics that, arguably, are even worse because they get into the bodies of every living thing on the planet. Whales. Birds. Earthworms. Human babies. 

So compostable plastics seem like an obvious and necessary shift, right Lou? Eureka! A plastic that we can toss into our compost bins and have it break down, along with organic waste, into soil and fertilizer. 

I tried it, Lou. The farmer from whom Dot’s family gets its veggies and meat delivers our goodies in compostable plastic bags. She used to reuse plastic bags that were donated by her customers. But since stores stopped giving out plastic bags, and most of her customers had come to rely on reusable totes, she began purchasing compostable plastic bags. It’s the responsible choice, right?

So I tossed a few of our farmer’s bags into our composter, which has been a champ at turning banana peels and tea bags and egg shells and so much more into black gold. And then, just this past weekend — close to one year on in my little compostable bag experiment — I lifted the little door at the bottom of our composter to remove the rich brown soil I intended to use when planting the Joe Pye-Weed and Turtlehead seedlings I’d just purchased. What did I find? The damn bags. A bit dirtier and tattier, sure, but otherwise pretty much the same as when I tossed them in. 

What the heck, huh, Lou? Why weren’t they dirt? Or at least less bag-like?

Prof. Mark Miodownik knows. The author of a paper on the subject published in the journal Frontiers in Sustainability said, in the National Observer, “The bottom line is that home compostable plastics don’t work.” He continued, “Let’s just stop. Let’s not pretend to ourselves that it’s going to be some sort of panacea, and you can sell people stuff without really having the infrastructure to deal with the waste and hope that it’s all going to go away.”

He sounds a bit angry, doesn’t he, Lou? And why wouldn’t he be? Why wouldn’t we be? These products are sold to us as a solution. Instead, they are often just replacing one problem with another. 

But let’s break down the problem, shall we? 

First, as Dot did with the doggie doo bags issue, let us consider the difference between compostable and biodegradable. We turn again to the in-the-know folks at Treehugger, who define biodegradable as “[able to] be broken down by microorganisms (like bacteria and fungi) and assimilated into the natural environment.” Note that biodegradation can take from a few weeks or months to, literally, centuries. A car is, technically, biodegradable. Consequently, something labeled “biodegradable” is offering useless information unless it is accompanied with a specific timeline — for instance, biodegradable within twenty-eight days — and information about under what circumstances the item will break down. It stands to reason that if you can’t create the necessary circumstances, then “biodegradable” is meaningless as a term of eco-friendliness. 

Compostable, our Treehugger friends inform us, “refers to a product or material that can biodegrade under specific, human-driven circumstances. Unlike biodegradation, which is an entirely natural process, composting requires human intervention.” Compostable products are further categorized into those compostable in a home system and those that require a more complex commercial facility, which, unfortunately, isn’t always available.

The labeling of compostable and biodegradable items is regulated by the FTC and third-party certification programs. But again, it doesn’t much matter what the label says if the appropriate circumstances — a commercial facility, say, or the presence of oxygen and microorganisms often absent in a landfill — aren’t available.

The New York Times offers an informative primer on some promising new packaging/single-use materials and also some potential pitfalls, concluding that “the best thing you can do environmentally is not create any waste in the first place.”

Dot concurs. As the renowned Canadian environmentalist David Suzuki once told Dot, the most environmentally sustainable choice is the product that will be reused over and over again. 

Which means, Lou, that it seems Dot can deliver a simple response, after all: Avoid one-and-done products even when they’re promising biodegradability and compostability. 

Biodegradably (within sixty-four days),


Got a question for Dot? Let her know here:

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