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Microplastics in tea bags

A research study by the University of Barcelona has found that many teabags are leaching billions of microplastic particles into our cups. This concern was reported by the BBC as far back as 19th September 2019. These particles are most readily absorbed by the mucus-forming cells in the gut and can pass into our blood-stream, thereby spreading throughout the body. Further concerns have been raised by the discovery that these plastics can pass though cell walls into the cell nucleus with consequences that are so far little known.

Between 39,000 and 52,000 particles are absorbed by the body each year depending upon age and gender. 20% of these particles have been found to be of concern to the European Union due to their persistence, accumulation in fatty tissues and toxicity. Ingestion is the principal way in which our bodies are exposed to these microplastics.

Non-biodegradable polypropylene is frequently used in manufacturing tea bags and food grade polymers such as nylon can break down when exposed to higher temperatures as experienced when brewing tea. Harmful particles are released above 40 degrees C and the high temperatures of brewing mean that the harmful effects are exacerbated. These plastics are used to seal the bags and can be used to reinforce the paper to help prevent the bags from bursting.

Absorption of these particles makes the body more susceptible to disease through weakening the body’s defenses. They can also upset the balance of flora in the gut leading to problems with metabolism and nutrition. Those suffering from gastrointestinal cancer have been found to have a higher concentration of micro-particles and nano-particles in the gut. They can also affect the production of hormones. The effect on the reproductive system due to the accumulation of these particles within cells is as yet little known. Furthermore, plastics found in the gut have been associated with conditions such as inflammatory bowel disease.

Tea should be infused with loose leaf tea in glass, ceramic or metal vessels although it is known that metal can taint the flavour of tea.

Researchers found that a plastic pyramid shaped teabag released about 11.6bn microplastic and 3.1bn smaller nanoplastic particles into hot water at 95 degrees, a typical temperature for brewing tea. Not only were they having an effect upon health but these single-use plastics are a hazard to the environment and even so-called bio-degradable teabags can take decades to degrade. Three different plastic-based teabag materials were chosen for the research:
• Those made primarily from polypropylene released about 1.2 billion particles per milliliter, averaging 136.7 nanometers in size.
• Cellulose bags released on average 135 million particles per milliliter, around 244 nanometers in size.
• The nylon-6 teabags typically released 8.18 million particles per milliliter, averaging 138.4 nanometers in size.

The effect of heat on plastics raises the wider issue of microparticles from other plastics heated to high temperatures used in the preparation of our food such as microwavable meal trays.

Take care to ensure that the teabags you might use are plastic-free. Loose leaf tea is the simple solution to this potential problem and the taste should be a whole lot better!

Additional sources:
Commercial tea bags release millions of microplastics when in use. University of Barcelona
Health risks posed by microplastics in tea bags: microplastic pollution – a truly global problem. Tooba Ali a, Ashna Habib a,*, Fiza Muskan a, Sadia Mumtaz a, Ramsha Shams b
Gooya Banaei et al, Teabag-derived micro/nanoplastics (true-to-life MNPLs) as a surrogate for real-life exposure scenarios, Chemosphere (2024).

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