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Teabags may be really bad for the environment, study finds

Plastic pollution is a growing concern, prompting manufacturers to seek alternatives like biodegradable plastics.
Plastic pollution is a growing concern, prompting manufacturers to seek alternatives like biodegradable plastics. (CREDIT: Creative Commons)

Plastic pollution is a growing concern, prompting manufacturers to seek alternatives like biodegradable plastics. However, a recent study highlights that some of these alternatives, specifically PLA-based teabags, may not degrade in soil as intended, posing potential risks to terrestrial species.

Researchers from the University of Plymouth conducted a study to examine the degradation of teabags made from polylactic acid (PLA), a bioplastic derived from renewable resources like corn starch and sugar cane. They tested three types of teabags: those made entirely from PLA and those made from a blend of cellulose and PLA. The teabags were buried in soil for seven months to observe their degradation.


The results were telling. Teabags made solely from PLA remained completely intact, showing no signs of breaking down. In contrast, teabags made from a mix of cellulose and PLA did degrade, losing between 60% and 80% of their mass. However, the PLA component within these teabags did not decompose, remaining as smaller pieces in the soil.

The study, published in Science of the Total Environment, also explored the effects of PLA on soil organisms, focusing on the earthworm species Eisenia fetida, which plays a crucial role in soil health by breaking down organic matter. Researchers exposed earthworms to varying concentrations of teabag discs, equivalent to the mass of half, one, and two teabags. They discovered that exposure to these PLA teabag discs resulted in up to a 15% increase in earthworm mortality. Moreover, certain concentrations of PLA negatively affected earthworm reproduction.


One significant finding of the study was the lack of clear disposal information on product packaging. Among the teabags tested, only one manufacturer indicated that their teabags were not suitable for home composting.

This lack of guidance can lead to teabags ending up in soil, contributing to environmental contamination. The study underscores the importance of providing consumers with accurate and clear information regarding the disposal of biodegradable products.


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Dr. Winnie Courtene-Jones, the study's lead author and a Post-Doctoral Research Fellow at the University of Plymouth, emphasized the need for more research on biodegradable plastics like PLA. "In response to the plastic waste crisis, biodegradable plastics such as PLA are being used in an increasing range of products.

This study highlights the need for more evidence on the degradation and possible effects of such materials before their use becomes even more widespread, and to prevent the generation of alternative problems if they are not properly disposed of," she stated.


Professor Antoine Buchard, a co-author of the study and a Professor of Sustainable Polymer Chemistry at the University of York, highlighted the potential for public misunderstanding regarding biodegradable labels.

"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, policymakers, and manufacturers work together to ensure clear standards are followed and that the public has easy access to information on where to dispose of these new plastics," he explained.


Broader Implications and Future Directions

The study is part of a larger research project, BIO-PLASTIC-RISK, funded by the Natural Environment Research Council. This four-year, £2.6 million project aims to assess how biodegradable packaging and products break down and their impact on both terrestrial and marine environments.

The findings also coincide with discussions at the Intergovernmental Negotiating Committee (INC-4) for the Global Plastics Treaty, highlighting the urgent need for international cooperation on plastic pollution. Professor Richard Thompson OBE FRS, Head of the University of Plymouth’s International Marine Litter Research Unit, stressed the importance of clear disposal guidelines.

"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 realized. 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 labeling these novel materials in relation to the prevailing waste management infrastructure," he remarked.


Dr. Mick Hanley, an Associate Professor in Plant-Animal Interactions at the University of Plymouth and senior author of the study, pointed out the risks to garden wildlife and food plants. "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 labeling 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," he warned.

This study highlights the critical need for clear labeling and disposal guidelines for biodegradable products like PLA-based teabags. As the use of such materials becomes more widespread, it is essential to ensure they do not inadvertently harm the environment they are meant to protect. By working together, scientists, policymakers, and manufacturers can help mitigate these risks and promote more sustainable practices.

For more environmental news stories check out our Green News section at The Brighter Side of News.


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