Research by the Autonomous University of Barcelona (UAB), as part of the European project PlasticHeal, has measured the release of millions of nanoplastics and microplastics from commercial polymer-based tea bags, following infusion.
The study (Banaei et al., 2024) shows for the first time the ability of these particles to be absorbed by cells in the intestine, reach the bloodstream and spread throughout the body. (1) An emerging public health risk that must be addressed without delay.
1) Plastics, microplastics and health. Introduction
The use of plastic materials in modern society is ubiquitous, in every productive sector, due to a series of key advantages including cost-effectiveness, versatility and lightness, among others. Even in the food packaging sector, still poorly regulated. (2)
Microplastic pollution is equally widespread, in the air as in water and food (3,4,5,6). And concerns about its possible impacts on human health have begun to be confirmed in recent years (7,8,9).
The health risks associated with exposure to plastics concern, in particular, both the toxic chemicals used as their additives, and their degradation into micro- (5 mm – 1 μm) and nanoplastics (<1 μm) (Jeong et al., 2024). (10)
2) Food contact materials
Plastic food contact materials can release greater or lesser quantities of microplastics and nanoplastics (MNPL) into foods and drinks, with potentially dangerous effects, which depend on:
– composition and physical-chemical properties of ‘food contact materials’
– environmental stressors (e.g. humidity, heat, light, microbial action or mechanical fragmentation).
The most common plastic packaging – containers, bottles, bags/filters and cups and films – are made from hydrocarbon polymers such as polyethylene (HDPE, LDPE), polypropylene (PP), polyesters (i.e. PET), polystyrene (PS) and PVC. (11)
The same polymers have been detected in various matrices including bottled water, food removed from non-stick cookware, ice cube bags, tea bags, take-away food containers, etc.
3) Microplastics released from polymer-based tea bags. The study
The tea bags stand out, among the various materials in contact with food, for their significant contribution to the release of millions of microplastics and nanoplastics (MNPL), adding to their daily ingestion by humans (Banaei et al., 2023). (12)
The objective of this research (Banaei et al., 2024) is to accurately characterize the toxicological profiles of MNPLs released from tea bags, in order to determine the interactive capacity of this type of exposure with the human organism.
3.1) Hundreds of millions of nanoplastics
Researchers examined different types of tea bags made from the polymers nylon-6, polypropylene and cellulose, available online (Amazon and Alibaba) both separately and inside commercial tea packages to wrap the leaves. Observing that, when used to prepare an infusion, they release enormous quantities of nano-sized particles and nanofilamentous structures, which represent an important source of exposure to MNPL:
– polypropylene, during the infusion of tea, 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;
– nylon-6 releases 8,18 million particles per milliliter, with an average size of 138,4 nanometers.
Particle characterization and measurement were performed with advanced analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), transfractural infrared spectroscopy (ATR-FTIR), dynamic light scattering (DLS), laser Doppler velocimetry (LDV) and nanoparticle tracking analysis (NTA).
3.2) Interactions with human intestinal cells
The Mutagenesis Group of the Department of Genetics and Microbiology at UAB then stained the particles and exposed them for the first time to different types of human intestinal cells, to evaluate their interaction and possible cellular internalization.
The experiments of biological interaction have shown for the first time that:
– mucus-producing intestinal cells have the highest absorption of micro- and nanoplastics;
– the absorbed particles even enter the cell nucleus that houses the genetic material.
The result suggests a key role for intestinal mucus in the absorption of these polluting particles and highlights the need for further research on the effects that chronic exposure may have on human health.
3.3) Provisional conclusions
The research was developed within the framework of the European project PlasticHeal, coordinated by Alba Hernández, professor at the Department of Genetics and Microbiology of the UAB, in collaboration with researchers from the Helmholtz Centre for Environmental Research in Leipzig (Germany).
‘It is essential to develop standardized test methods to assess MNPL contamination released from food contact plastic materials and formulate regulatory policies to effectively mitigate and minimize this contamination.
As the use of plastic in food packaging continues to increase, addressing MNPL contamination is critical to ensure food safety and protect public health‘, the researchers conclude.
4) Risk assessment and management
The emerging risks highlighted in the research under examination are relevant under both the safety profiles of materials and objects in contact with food and food safety. From this derives a double responsibility, respectively on the part of:
– producers, importers and distributors (including remote ones) of ‘food contact materials’ and of tea and infusion preparations in bags based on polymers derived from hydrocarbons. General Product Safety Regulation (EU) No 2023/998, GPSR, states the duty to place on the European market products (including food contact materials) that are strictly safe, on the basis of an appropriate risk assessment (14,15);
– Member States and the European Commission in turn, already pursuant to the Food Contact Materials Regulation (EC) 1935/04 have a duty to adopt safeguard measures, such as restrictions and prohibitions on the use of certain materials in contact with food, where it appears that they may pose risks to human health. (16)
GPSR then introduced the (only) faculty to adopt ‘measures prohibiting, suspending or restricting the placing or making available on the market of such products or establishing special conditions for their assessment of conformity with safety requirements‘, against products which present a serious risk to the health of consumers. (17)
5) Tea and herbal teas, advice for consumers
Tea and herbal teas are excellent drinks in themselves that contribute to the hydration of the body with an additional flavour and sometimes also polyphenols or other bioactive substances. Without ‘adding calories’ to the diet, provided that sugars are not added (the consumption of which must always be limited to a minimum, in every phase of life, according to well-established nutritional recommendations). (18)
The choice of these drinks should first of all be oriented towards organic products, to avoid unnecessary exposure to pesticides and other agrotoxics, even those banned in the EU, which often remain in them, as revealed by a recent test of 60 million consumers (2022). (19)
The results of this study also suggest that the purchase of tea and herbal teas packaged in polymer-based sachets should be avoided in order to avoid exposure to microplastics and plastic additives that are certainly harmful to human health. Therefore, favour ‘plastic-free’ sachets or use stainless steel filters, which present no risk of migration and are reusable for life.
Dario Dongo
Footnote
(1) Banaei G, Abass D, Tavakolpournegari A, Martín-Pérez J, Gutiérrez J, Peng G, Reemtsma T, Marc R, Hernández A, García-Rodríguez A. (2024). Teabag-derived micro/nanoplastics (true-to-life MNPLs) as a surrogate for real-life exposure scenarios. Chemosphere. 368:143736. doi: 10.1016/j.chemosphere.2024.143736
(2) Marta Strinati, Dario Dongo. Chemical toxicity of food contact materials, researchers appeal. FT (Food Times). March 12, 2020
(3) Dario Dongo. Microplastics away in the wind, contaminated even the air. FT (Food Times). April 29, 2019
(4) Dario Dongo. Microplastics in drinking water, WHO calls for risk assessment. FT (Food Times). August 22, 2019
(5) Sabrina Bergamini, Dario Dongo. Microplastics on the plate, two new studies and a petition. FT (Food Times). June 13, 2019
(6) Marta Strinati. Microplastics inside fruits and vegetables. The Italian study. FT (Food Times). June 21, 2020
(7) Paola Palestini, Dario Dongo. Microplastics and human health, the invisible evil. FT (Food Times). March 28, 2019
(8) Marta Strinati. Microplastics, new evidence of genotoxicity on freshwater shrimps. FT (Food Times). March 16, 2023
(9) Marta Strinati. Microplastics, a new cardiovascular risk factor. FT (Food Times). March 11, 2024
(10) Jeong, J., Im, J., Choi, J. (2024). Integrating aggregate exposure pathway and adverse outcome pathway for micro/nanoplastics: a review on exposure, toxicokinetics, and toxicity studies. Ecotoxicol. Environ. Saf. 272, 116022. https://doi.org/10.1016/j.ecoenv.2024.116022
(11) Dario Dongo, Andrea Adelmo Della Penna. PVC, serious risks on transparent films and other packaging. FT (Food Times).
(12) Banaei, G., García-Rodríguez, A., Tavakolpournegari, A., Martín-Perez, J., Villacorta, A., Marcos, R., Hernandez, A.(2023). The release of polylactic acid nanoplastics (PLA-NPLs) from commercial teabags. Obtention, characterization, and hazard effects of
true-to-life PLA-NPLs. J. Hazard Mater. 458, 131899. https://doi.org/10.1016/j.jhazmat.2023.13189
(13) Plastic Heal https://www.plasticheal.eu/en
(14) Dario Dongo, Alessandra Mei. General Product Safety Regulation, at the starting tape in the European Union. THE ABC’S. FT (Food Times). May 13, 2023
(15) Regulation (EU) 2023/988 of the European Parliament and of the Council of 10 May 2023 on general product safety (https://tinyurl.com/3wuhtw8n). See Articles 5,6,8,9,11,12
(16) Regulation (EC) No 1935/2004 of the European Parliament and of the Council of 27 October 2004 on materials and articles intended to come into contact with food. Consolidated text, 28 March 2021 https://tinyurl.com/2asdt22p See Article 18 (safeguard measures)
(17) GPSR, Article 28
(18) Marta Strinati. The harmful role of sugars in the diet, EFSA opinion. FT (Food Times).
(19) Marta Strinati. Pesticides in the cup of tea and herbal teas. Test on 48 products. FT (Food Times).
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
