"Biodegradable," "compostable," and "oxo-biodegradable" get printed on packaging as if they mean the same thing. They don't — and the difference matters for your business, your customers, and the environment.
Biodegradable: a broad, loosely-defined claim
Technically, "biodegradable" just means a material can be broken down by microorganisms eventually. There's no fixed timeframe and no guarantee about what's left behind. Under the right conditions, almost anything is biodegradable given enough time — including some conventional plastics, which can take decades. Because the term isn't tied to a specific standard, it's the easiest one for low-quality products to misuse.
Compostable: biodegradable, with proof
Compostable is a stricter claim. A genuinely compostable bag breaks down within a defined period (typically 180 days in industrial composting conditions), leaves no toxic residue, and turns into usable compost — water, CO2, and biomass. To legitimately call a product compostable, it needs to pass certification testing against standards like EN 13432 or ASTM D6400, which we cover in detail in a separate guide.
This is the category Greensack bags fall into: made from plant-based materials such as cornstarch, PLA, and PBAT, engineered specifically to compost fully rather than just "eventually break down."
Oxo-biodegradable: the one to watch out for
Oxo-biodegradable (sometimes called "oxo-degradable") bags are conventional plastic with a chemical additive that makes the plastic fragment into smaller pieces faster when exposed to heat, light, or oxygen. This is the critical difference: the plastic doesn't turn into compost — it turns into microplastics. Regulators in the EU and several other markets have restricted oxo-degradable plastic specifically because of this concern.
If a bag "breaks apart" quickly but the packaging doesn't mention a compostability certification number, it's worth asking whether it's oxo-biodegradable rather than genuinely compostable.
How to tell them apart at a glance
| Term | What actually happens | Certification required? |
|---|---|---|
| Biodegradable | Breaks down eventually — timeframe and residue not defined | No |
| Compostable | Fully converts to compost within a defined period, no toxic residue | Yes (EN 13432 / ASTM D6400) |
| Oxo-biodegradable | Fragments into microplastics; does not compost | No recognised compostability standard |
Why this matters for your business
- Regulatory risk: Many state and municipal plastic bans specifically exempt certified compostable bags — but not biodegradable or oxo-biodegradable ones.
- Brand risk: Customers are increasingly aware of "greenwashing." Using a vaguely-labelled bag and calling it eco-friendly can backfire if questioned.
- Actual environmental impact: Only certified compostable packaging reliably avoids contributing to microplastic pollution.
The simple rule
When evaluating any packaging supplier's sustainability claim, ask for the certification number and testing standard. If they can't provide one, treat "biodegradable" or "eco-friendly" as marketing language rather than a verified fact.