Oxo-degradable straws: magic or myth?

The oxo-biodegradable straw: the straw that is cheap and degrades into smaller pieces that pose no threat to our environment within months after its useful life. That sounds like a strawesome solution for plastic pollution, right? It is exactly these green marketing claims that increase the popularity of oxo-biodegradable straws as an alternative for plastic straws at the European market. However, recent studies and reports overwhelmingly suggest that oxo-biodegradable plastic is not a solution to soil or marine pollution - on the contrary, it contributes to microplastic pollution, poses an environmental risk and does not fit in a circular economy.

But what is an oxo-biodegradable straw exactly?
Oxo-degradable plastic straws, often called ‘eco straws’ in the general market, are actually just conventional plastic straws which include (often toxic) additives to accelerate the fragmentation of the material into very small pieces. The straws are often marketed as a solution to plastic pollution, claiming that the straws degrade into harmless residues within a period ranging from a few months to several years. However, a recent report by the EU Commission states that oxo-biodegradable plastics do not biodegrade but merely fragment into small pieces, also called microplastics, that remain in and potentially harm the environment and endanger recycling and composting.

Challenges with biodegradation
The degradation of oxo-degradable plastic straws happens in two faces. First, the straw needs to fragment into smaller pieces (reduced molecular weight). In theory, this fragmentation should then accelerate the process of biodegradation, i.e. the breakdown triggered by micro-organisms into natural molecules such as carbon dioxide and water.

However, for the fragmentation into smaller pieces the straw needs to be exposed to oxygen, heat and at least 48 hour of sunlight. If these conditions are not met, which is likely in trash bins and landfills, the straw will never reach the reduced molecular weight needed to fully biodegrade. Instead, the straws fragment into smaller plastic pieces, also called microplastics. This way oxo-degradable plastic contributes to  the  microplastics  release  in  the  (marine)  environment  while  misleading  consumers. 

Risk of microplastic pollution
These microplastics pose a great environmental risk, particularly in the ocean where microplastics are eaten by fish and eventually end up in our food chain. A recent study suggests that tiny plastic particles may already be widespread in our food. The small study examined eight participants from Europe, Japan and Russia. All of their stool samples were found to contain microplastic particles. Dr. Philip Schwabl, who presented the findings of the study explains that “the smallest microplastic particles are even capable of entering the bloodstream, lymphatic system, and may even reach the liver." Scientists still know little about the effects of microplastics once they enter the human body, though many studies have already found them present in foods such as fish and table salt that people are likely to eat. The UK government has launched a study to examine the health impacts of microplastics.

Oxo-degradable straws are not circular
Another major concern of oxo-degradable straws is that they are not suitable for recycling or composting.  As the straws are made of conventional plastic with a (toxic) additive, they are not suitable for either plastic recycling or composting. With current technologies they cannot be identified and sorted separately and therefore can negatively affect the quality of recycled plastic products and compost. Thereby oxo-degradable straws go against two key principles of the circular economy: designing out waste and pollution and keeping products and materials in high-value use.

 EU ban on oxo- biodegradable plastics
As a result of the significant body of evidence raising concerns that oxo-biodegradable plastics fragments into microplastics that pollute oceans, the European Commission said it will take steps to “restrict the use” of oxo-biodegradable plastics across the EU. While some EU Member States have already set an example and restricted the use of oxo-degradable plastics, including France and Spain, most EU countries still falsely market oxo-degradable plastics as a solution to the plastic waste and littering problem.

The negative effects on the environment, however, must not be neglected. As a journalist of the Guardian wisely said “throwing oxo-biodegradable plastics away in the hope that a magic formula will guarantee their rapid disappearance is laziness, not environmental care. And anybody who tries to persuade us otherwise is guilty of Greenwash.”