Researchers from the Autonomous University of Barcelona, Spain, have provided insights into how tea bags contribute to daily human ingestion of micro- and nanoplastics (MNPLs). This study confirmed the release of MNPLs from three commercially available tea bags, which all showed varying levels of nano-range particle (NPL) internalization in human intestinal cells.

The study, published in the peer-reviewed journal Chemosphere, highlights the release of MNPLs from polymer-based teabags into the aqueous phase during typical usage and underscores the need to understand their toxicological effects on human health.

Alba Garcia Rodriguez, corresponding author from the Department of Genetics and Microbiology at UAB, tells Packaging Insights: “Industry stakeholders can play a crucial role by minimizing the use of plastics that are prone to shedding micro- and nanoplastics, especially in products that come into contact with F&B.”

“Prioritizing alternative materials with verified low particle release, improving product labeling, and investing in green packaging innovation are all important steps. Transparency regarding material composition and consumer education about safe usage — such as avoiding high temperatures with plastic containers — are also essential to reduce unintentional exposure.”

Advancing methodologies

The study investigated three different types of tea bags with distinct chemical compositions, namely, empty nylon-6 (NY6) teabags representing polyamide, empty PP teabags, and commercially available teabags containing tea, with cellulose (CL) as the polymer composition.

In terms of the research process, Rodriguez emphasizes the urgent need for researchers to standardize methodologies for assessing the release and toxicological effects of MNPLs.

“One of the key challenges in MNPL research is the lack of standardized protocols for sample preparation, characterization, and toxicological assessment. We advocate for the adoption of ‘true-to-life MNPLs,’ which most recently have been coined as real-life MNPLs, derived from real consumer products, instead of using laboratory-made MNPLs that poorly mimic what is found in our ecosystems.” 

“Furthermore, advancing in analytical approaches and methodologies such as electron microscopy, FTIR spectroscopy, and Raman spectroscopy is also urgent since most existing techniques are still not fully adapted for the detection or quantification of MNPLs, particularly in the nano-range, and remain poorly suited for analyzing complex mixtures containing diverse and heterogeneous particles,” she shares.

“Such advances will be essential to accurately quantify human exposure to MNPLs and to enable more robust, realistic, and reliable human health risk assessments, ultimately informing evidence-based regulatory decisions and protective public health strategies.”

Uncovering the health risks

To characterize the MNPLs released from teabags, the researchers employed multiple analytical techniques.The results confirmed the presence of microfibers and NPLs in the leachates from herbal and tea bags composed of NY6, PP, and CL.

“Our study demonstrates that mucus-producing intestinal cells, particularly goblet-like cells such as HT29-MTX, exhibit a higher degree of interaction and internalization of MNPLs compared to non-mucus-producing cells.”

“This suggests that the mucus layer, typically seen as a protective barrier, may actually facilitate the adhesion and uptake of MNPLs’ under certain conditions. Given that these particles can reach ‘easily’ or ‘faster’ the cell nucleus and potentially interfere with cellular functions, there is a growing concern about the MNPLs long-term effects, which may include inflammation, barrier dysfunction, or even genotoxicity.”

The scientists believe their findings should inform regulatory efforts to reduce plastic contamination in food-contact materials. 

Last month, US researchers detected increasing concentrations of microplastics in the human brain. They found that MNPLs appear to be higher in dementia samples.