The European Bioplastics Association has released a publication called “CLAIMS ON BIODEGRADABILITY AND COMPOSTABILITY ON PRODUCTS AND PACKAGING". This document recaps the definition of potentially confusing terms like biodegradability, compostability, industrially compostable, home compostable or soil biodegradable.
A product is designed to biodegrade in a certain environment which can be natural (soil, marine, fresh water) or monitored (compost). Biodegradability claims must always specify the receiving environment and be justified by certifications like the EN13432. For instance, PLA is biodegradable in an industrial composter, it is industrially compostable according to EN13432.