Study suggests ‘biodegradable’ teabags don’t readily deteriorate in the environment and can adversely affect terrestrial species

After 30 years of research on plastic pollution I am delighted there is now a global consensus, as evidenced by the UN Plastics Treaty, that current production use and disposal of plastic is unsustainable. But it is with immense frustration that I see alternative and substitute materials entering the market without clear guidance on how their benefits might be realised. Even if consumers understand how to dispose of these products only around half of households in the UK currently have access to the necessary waste streams for the type of composting required. It is essential we learn from the mistakes we made with plastic materials by testing and labelling these novel materials in relation to the prevailing waste management infrastructure.

In this study PLA-based teabags did not fully deteriorate, and it seems that composting worms may be harmed by them. The lack of clear labelling can lead to consumers disposing of teabags in their compost, where any limit to complete degradation of the material raises the potential for plastics to enter the soil when compost is added to the garden, with potential impacts on garden wildlife and uptake by food plants.

PLA is a bioderived plastic with a reduced carbon footprint compared to traditional plastics, which also degrades under industrial composting conditions. Using a number of chemical analysis techniques, we've shown that when it is not properly disposed of, for example after seven months in the soil, its molecular structure remains intact. Labels such as biodegradable and compostable have the potential to mislead the public, therefore it is important that scientists, policy makers and manufacturers work together to ensure clear standards are followed and that the public has easy access to information on where to dispose of those new plastics.