October 18, 2016
Biobased, Biodegradable, Compostable … How Are They Different?
These terms are often used interchangeably, but they each have distinct meaning and nuanced differences. In simplest terms, most biobased materials are biodegradable, and some biodegradable materials are compostable.
The term “biobased” refers to material feedstock sourcing – the beginning of a package’s life cycle.
A biobased material is made from renewable plant or animal feedstocks. The terms “biobased,” “renewable,” and “biotic” are interchangeable. Tree fiber-based packaging materials are the classic example of biobased packaging, and the realm of fiber-based packaging materials is complemented by novel uses of other biobased sources of fiber such as wheat straw, kenaf, and bamboo. The other realm of biobased packaging materials are bioplastics. Bioplastics can be made from an equally diverse range of feedstocks, including corn starch, sugarcane, and a wide variety of other sources like potatoes, algae, mycelium (mushroom “roots”), and food waste.
The ASTM D6866 test standard can be used to quantify a material’s biobased content, and guidance for marketing claims of biobased materials is given in section 260.16 of the Federal Trade Commission’s Guides for the Use of Environmental Marketing Claims.
The term “biodegradable” refers to a material’s ability to decompose via microbial activity. Biodegradability and compostability both refer to a package’s end-of-life.
Most, but not all, biodegradable packaging materials are biobased. It shouldn’t be assumed that every biobased packaging material is biodegradable nor that every biodegradable material is biobased. For example…
- BASF’s ecoflex(R) is a biodegradable polymer that is not biobased, being a fossil-based aliphatic-aromatic copolyester that meets the ASTM standards for biodegradability and compostability.
- Braskem’s Green Polyethyelene is a biobased polymer that is not biodegradable, being chemically indistinguishable from conventional non-biodegradable polyethylene.
The SPC views compostability as a more meaningful indicator of a package’s ability to undergo an environmentally beneficial process at end-of-life, and hence the SPC does not encourage marketing claims of biodegradability. The SPC has a formal position against the use of biodegradability additives in conventional petroleum-based plastics.
The term “compostable” refers to a material’s ability to biodegrade within a sufficiently short amount of time in the conditions of a composting operation. Many biodegradable products are not compostable, and the terms should not be considered to be equivalent.
Home composting and industrial composting are distinct, and compostability should be classified accordingly. Parameters including heat, aeration, and carbon-to-nitrogen ratio, are more controlled at industrial composting operations, and the time requirements for total biodegradation are very stringent. ASTM D6400 is the chief testing method for determining whether or not a package is compostable in industrial operations. While there is no equivalent testing method for home compostability, a Belgian certification protocol administered by Vinçotte is used to certify home compostability. Guidance for marketing claims of compostability is given in section 260.7 of the Federal Trade Commission’s Guides for the Use of Environmental Marketing Claims.
The SPC encourages marketing claims of compostability via the How2Compost labeling system.