Scientists have discovered dangerous elements in tea bags

Scientists from the Autonomous University of Barcelona (UAB) have discovered that polymer tea bags available in ordinary shops release millions of nanoplastics and microplastics when brewed. For the first time, they were able to show that these particles are able to penetrate human intestinal cells and possibly enter the bloodstream, spreading throughout the body.

Unfortunately, plastic pollution is becoming an increasingly serious problem that threatens future generations. Meanwhile, food packaging acts as a key source of microplastics and nanoplastics (MNPLs). We can inhale these particles or ingest them along with our food.

As part of the study, scientists first isolated microplastics from several types of shop-bought tea bags. They then found that when a tea bag is brewed in a cup, it releases colossal volumes of tiny pieces of plastic as well as nanofibres. This is how these foreign particles can enter the body.

The bags used in the experiment were made of nylon-6, polypropylene and cellulose. The polypropylene bags were found to release about 1.2 billion particles per millilitre of brewed tea, the cellulose about 135 million, and the nylon-6 about 8.18 million. The average size of the particles released ranged from 136 to 244 nanometres. Advanced analysis techniques used for detailed study were scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (ATR-FTIR), light scattering (DLS), laser Doppler velocimetry (LDV) and nanoparticle tracking (NTA).

To test how these particles interact with human cells, the researchers coloured the plastic and added it to different types of intestinal cells. What was most surprising was that the intestinal mucosal cells absorbed the most nanoparticles, and some even penetrated the cell nucleus, where genetic material is stored. This suggests the importance of intestinal mucus in the process of "capturing" contaminating particles and points to the need for further research, especially into the health effects of long-term (chronic) ingestion of microplastics.

Experts emphasise that uniform standards are needed to assess microplastic pollution from plastic packaging, as well as laws regulating the safe use of such materials.

Source:
Banaei et al, Teabag-derived micro/nanoplastics (true-to-life MNPLs) as a surrogate for real-life exposure scenarios, Chemosphere (2024). DOI: 10.1016/j.chemosphere.2024.143736