Commercial tea bags release millions of microplastics, which enter human intestinal cells

UAB research has characterized in detail how polymer-based commercial tea bags release millions of nanoplastics and microplastics when infused. The research shows for the first time that these particles are able to be absorbed by human intestinal cells, allowing them to reach the bloodstream and spread throughout the body.

Plastic waste pollution represents a critical environmental challenge, with increasing consequences for the well-being and health of future generations. Food packaging is a major source of contamination with micro- and nanoplastics (MNPLs), and inhalation and ingestion are the main routes of human exposure.

A study by the Mutagenesis Group of UAB’s Department of Genetics and Microbiology has successfully obtained and characterized micro- and nanoplastics derived from several types of commercially available tea bags. The article is published in the magazine Chemosphere.

The UAB researchers found that when these tea bags are used to prepare an infusion, massive amounts of nanoparticles and nanofilamentous structures are released, which is a major source of exposure to MNPLs.

The tea bags used for the study are made of the polymers nylon-6, polypropylene and cellulose. The research shows that when brewing tea, polypropylene releases approximately 1.2 billion particles per milliliter, with an average size of 136.7 nanometers; cellulose releases approximately 135 million particles per milliliter, with an average size of 244 nanometers; while nylon-6 releases 8.18 million particles per milliliter, with an average size of 138.4 nanometers.

To characterize the different types of particles present in the infusion, a range of advanced analytical techniques are used, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (ATR-FTIR), dynamic light scattering (DLS), laser Doppler velocimetry (LDV) and nanoparticle tracking analysis (NTA) were used.

“We have managed to innovatively characterize these pollutants using a series of advanced techniques, which is a very important tool to advance research into their potential impacts on human health,” said UAB researcher Alba Garcia.

Interactions with human cells observed for the first time

The particles were first stained and exposed to different types of human intestinal cells to assess their interaction and possible cellular internalization. The biological interaction experiments showed that mucus-producing intestinal cells had the highest uptake of micro- and nanoplastics, with the particles even entering the cell nucleus where the genetic material is located.

The result suggests a key role for intestinal mucus in the absorption of these pollutant particles and underlines the need for further research into the effects that chronic exposure may have on human health.

“It is critical to develop standardized testing methods to assess the contamination of MNPLs released from plastic food contact materials and to formulate regulatory policies to effectively reduce and minimize this contamination. As the use of plastic in food packaging continues to increase, it is critical to tackle MNPLs. contamination to ensure food safety and protect public health,” the researchers added.