Billions of Plastic Particles in Your Teacup? A New Study Exposes the Invisible Risk

Redacción HC
22/04/2025

Every day, millions of people around the world enjoy a calming cup of tea. But what if that simple act of wellness is also exposing your body to billions of microscopic plastic particles? A groundbreaking study published in Chemosphere (2024) reveals that commercial tea bags—particularly those made from synthetic materials—release staggering amounts of micro- and nanoplastics (MNPLs) when infused. Even more concerning, these particles can penetrate human intestinal cells, raising red flags for public health.

Led by a team of researchers from Universitat Autònoma de Barcelona, Helmholtz Centre for Environmental Research, and Sohag University, the study presents the most realistic and detailed look yet at how we might be unknowingly ingesting plastic through everyday habits—and how those particles interact with our cells.

From Teacup to Cells: What This Study Uncovered

Brewing More Than Tea: The MNPL Extraction Process

To replicate real-life exposure, scientists infused three types of commercially available tea bags made of polypropylene (PP), nylon-6 (NY6), and cellulose in hot water. The infusion process mimicked typical tea preparation at home.

Advanced analytical techniques—including SEM, TEM, ATR-FTIR, DLS, LDV, and NTA—were used to characterize the released particles. The results were startling:

• Polypropylene bags released up to 1.2 billion particles per milliliter.
• Cellulose bags released approximately 135 million particles/mL.
• Nylon-6 bags released over 8 million particles/mL.

These particles ranged in size from 136 to 244 nanometers, with a mixture of microfibers and nanoplastics—a blend rarely captured in earlier lab studies.

Cellular Consequences: How MNPLs Behave in the Body

Testing on Human Intestinal Cells

In the next phase, researchers exposed three human intestinal cell lines—Caco-2, HT29, and HT29-MTX (the latter mimicking mucus-producing gut cells)—to extracted MNPLs in a controlled in vitro environment.

Using fluorescent dyes and 3D confocal microscopy, they observed how the particles interacted with the cells over 24 hours. The results revealed:

• HT29-MTX cells internalized the most polypropylene particles, likely due to their mucus layer, which may act as both a barrier and a trap.
• Caco-2 cells preferentially absorbed nylon-6 nanoparticles.
• Some particles reached the nuclei of intestinal cells—suggesting a risk of potential genomic interference.

“These are not just inert particles,” the authors note. “They are capable of penetrating deep into human cellular structures.”

Real-World Risk: What These Findings Mean for You

The Plastic in Your Cup—and Your Gut

This is one of the first studies to use “true-to-life” MNPLs—actual particles released from consumer products—instead of synthetic lab-generated particles. It confirms that even a single cup of tea may contain millions to billions of plastic particles, depending on the bag type.

And while the study was conducted in vitro, meaning outside a living organism, the implications are serious. If these particles are absorbed by gut cells in lab conditions, it is reasonable to suspect they might behave similarly in the human body—especially with regular, long-term exposure.

Implications for Policy and Public Health

Should We Be Rethinking How We Brew Tea?

This research has sparked renewed calls for stricter regulations on food-contact materials, especially plastic-based teabags, which are often marketed as “premium” or “eco-friendly” alternatives. The authors urge food safety authorities to consider:

• Standardizing MNPL measurement in consumer products.
• Limiting use of polymers that release high levels of nanoparticles when heated.
• Promoting alternative materials such as uncoated paper or metal infusers.

“The lack of regulatory thresholds for nanoplastics in food products is a glaring gap,” warns co-author Alba García-Rodríguez.

How to Protect Yourself: Practical Tips

Until policy catches up, consumers can take steps to reduce potential MNPL exposure:

1. Avoid nylon or plastic mesh tea bags—opt for paper or loose-leaf tea instead.
2. Use metal or glass tea infusers, which release no microplastics.
3. Limit reuse of single-use bags, especially those that appear synthetic or glossy.
4. Look for transparency in labeling—brands that disclose their packaging materials.

Scientific Significance and Next Steps

What This Study Adds to Existing Literature

This study builds on earlier findings (e.g., Hernández et al., 2019) by demonstrating that commercial plastic teabags, not just polystyrene beads in lab tests, can release massive quantities of MNPLs—and that these particles are readily internalized by human intestinal cells.

Future research will need to assess chronic exposure risks in animal models and human subjects, especially regarding inflammation, genotoxicity, and gut barrier function. Understanding how MNPLs interact with the microbiome will also be a crucial next step.

Final Thoughts: Tiny Particles, Big Questions

The idea that sipping tea might expose us to billions of plastic nanoparticles challenges assumptions about what’s safe, natural, or healthy. While more research is needed to fully understand the biological impact, the takeaway is clear: common food-contact materials can release harmful particles under ordinary conditions.

As scientists push for tighter regulation and better public awareness, one thing is certain: we need to pay closer attention to what we can't see—especially when it comes to what goes into our bodies.

Topics of interest

Pollution Health