Francesco Degli Innocenti, EUBP Working Group Standardisation
The development of a framework for bio-based and biodegradable/compostable plastics is a key deliverable of the new Circular Economy Action Plan, which was published by the European Commission in March 2020. Several studies have been launched and published since then to lay down the scientific basis for this framework. One of them is the report “Biodegradability of plastics in the open environment” by SAPEA (Science Advice for Policy by European Academies). The report correctly confirms a role for biodegradable plastics within a circular economy. Unfortunately, it also includes a number of unfounded general assumptions that need to be rectified, especially with regards to the general understanding of biodegradability. Read in the following a guest commentary by Francesco Degli Innocenti, Member of the European Bioplastics Working Group Biodegradables and Chair of the Working Group Standardisation.
A stone held in our hands, does not fall down. In this moment, gravity does not matter, is non-existent, the stone is not moving. One could conclude that, when the stone is in the hand, gravity does not exist. As soon as we open our hands, gravity is back, and the stone falls to the ground. However, physics takes a different approach to describe this phenomenon. Gravity is existent, before and after the falling. Before it does not play a role because the hand prevents the gravitational potential energy from transforming into kinetic energy. Or in simple words: the gasoline in a car tank does not catch fire but no one doubts that it is fuel. However, it is wrong to assume that gasoline, at that moment, does not burn, because it is not inflammable. It becomes flammable as soon as certain conditions, for example temperature or oxygen supply, become favourable to the real and evident manifestation of combustion. Chemistry, using an approach similar to that of physics, describes the phenomenon in a different way: each substance has its own intrinsic reduction potential which describes the tendency of a chemical species to react with oxygen (i.e. to burn). The reduction potential is present, even when conditions are not suitable for a redox reaction to occur.
In a study on Biodegradability of Plastics in the Open Environment published by SAPEA end of 2020, “biodegradability is considered to result from the interplay between material properties that provide the potential for biodegradation to occur, in combination with the environmental conditions that match this potential and, thereby, allow for biodegradation to occur”. The SAPEA report calls this interplay “system property”. In some cases, the report calls biodegradation a system property but then also biodegradability is described as a system property, as if the two terms “biodegradation” and “biodegradability” were synonym