Tea Advisory Panel

Confused about micro and nano particles that are in the air, water and sometimes referenced in relation to food and drink packaging? You are not alone. The review by Fard et al (2025)[1] of the published research to date illustrates the fact that this is an emerging area of science where vastly differing methods of sample treatments, preparation and analysis, generate results that are totally flawed and hard if not impossible to strictly compare scientific methods. In the following e-news from the Tea Advisory Panel – TAP – www.teaadvisorypanel.com - an independent panel of doctors, scientists, dietitians, nutritionists, chemists and researchers - Dr Tim Bond from TAP sorts fact from fiction on the matter of microplastics.

No evidence of any health risks
Dr Tim Bond notes with reference to work done on drinking water “The World Health Organisation (WHO) has stated that looking at current research they conclude that no reliable information suggests microplastics are a health risk for consumers.[2] In a statement published on August 5, 2025 the BfR (the German Federal Institute for Risk Assessment), following its own assessment of studies on tea bags, said that health impairments are not expected according to current knowledge.[3] In the BfR’s opinion there is also no evidence to support the view that microplastics accumulate in the brain.

In the UK, the Food Standards Agency (FSA) continues to monitor and assess emerging data regarding microplastics in food. The Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment (COT), an independent scientific committee that provides advice to the Food Standards Agency (FSA) and other Government departments has previously concluded that the available data was insufficient for a complete assessment.

As a result, the FSA has advised that, based on current information, they consider it is unlikely that the presence of these particles in food or drink would cause harm to consumers.^[4]

Review of flawed research on microplastics from teabags
Like all scientific research, understanding how the study data has been determined and the resulting research findings is essential.  Dr Tim Bond notes: “It is important to stress that no evidence has been found in microplastic studies to date that tea poses a consumer health risk and all the research published to date in this area has been hugely flawed. As a result, we should not be drawing any conclusions from research which is unsound.”

“The review by Fard et al (2025)[5] started with a total of 890 original articles which were reduced to only 19 that met the authors criteria and even with these criteria applied the articles varied significantly in the number of samples – from 2 to 28 (extremely small for a scientific publication) that were tested to the methods applied, and critically the steps taken to avoid general environmental contamination.”

“For example, in a 2019 study from McGill University, Canada[6], a chemical engineering team looked at the release of micro and nano particles from Nylon and PET (Polyethylene terephthalate) based tea bags. The researchers cut open a very small number of tea bags, emptied out the tea, steeped the bags at a brewing temperature of 95^oC and then measured the numbers of micro and nano particles. The researchers concluded that steeping a single plastic tea bag at brewing temperature (95°C) released a number of micro- and nano-plastics. In reality this was a minute amount. The research focused on only two types of tea bags - Nylon and PET. The majority of teabags in the UK are made from natural, plant fibres so the research findings have no relevance to UK tea drinkers.”

Dr Tim Bond continues: “There are a number of major flaws with this study. Micro and nano particles are very hard to capture, and it is even harder to estimate accurate quantities due to the small sample sizes. Micro particles are typically 100 nanometers-5 millimetres and nano plastics are particles <100 nanometres in size. For reference a human hair is approximately 80,000- 100,000 nanometres wide[7]. The researchers tried to remove all non-teabag sources of micro and nano particles in the experiments, but this is a challenge and an additional disadvantage of the experimental design and hence a major study flaw. As a result, very poor science like this should not be reported on or published and hence should be ignored.”

Dr Tim Bond explains further: “The lack of data provided in the publication on how the calculations of the final numbers of plastic particles were made, makes the results impossible to assess and evaluate. Furthermore, Nylon and PET plastics are ubiquitous in plastic packing, films etc. and have been tested and approved as food safe by governments around the world for decades.”

Soon after the publication of the Hernandez et al., 2019 study from McGill University, Busse[8] et al., a team of food chemists and food safety professionals reviewed the test methods used in the study and used more appropriate analytical method to examine similar teabags. They concluded that the findings of zero microplastic particles in their ‘control/ blank’ was highly unlikely, that all particles (even tea particles) were categorised as micro / nano plastics and that the total number of particles found had been extrapolated from an overestimated base number. They summarised that  “we encourage the reader to rethink critically about the results presented by Hernandez et al. Further, more detailed experiments are needed to definitely evaluate a potential release of microplastics by plastic teabags.”

Dr Tim Bonds adds: “Since 2019 various authors  and studies, such as Banaei et al (2024)[9] have referenced the Hernandez et al paper either copying the flawed analytical methodologies or referencing the debunked outcomes.  Busse et al is rarely referenced on the same work and where they are, the paper is noted as only supportive, rather than recognising the authors critically examined the dubious methodologies used by Hernandez et al and the resulting findings being very questionable.”

Regarding the 2024 paper by Banaei et al., Dr Tim Bond explained, “The methodologies used in this paper - Teabag-derived micro/nanoplastics as a surrogate for real-life exposure scenarios – were very similar methodologies to a previously flawed paper in 2023[10] and like that paper, the 2024 paper has taken a discredited research approach (Hernandez et al[11]) as a base point. As a result, Banaei et al., (2024) should be totally disregarded, has no relevance to the tea drunk in the UK and is another example sadly of poor science.

“Looking at the study in more detail, the authors sourced a single brand of tea from a local market [in Spain] and used a preparation method that they describe as mimicking a traditional cup of tea. However, the authors took 300 tea bags and had the tea removed. The tea bags were them placed in 600ml water preheated to 95^oC with constant stirring peaking at 750 revolutions per minute. This methodology is totally irrelevant to a UK consumer, as they would not cut tea bags, empty the tea and then stir for an unknown period of time with stirring up to 750 rpm and extensive bag-on bag agitation -which the authors themselves comment on.

“Of relevance in the current study of the three tea bag materials studied (nylon, polypropylene and cellulose) only the latter – cellulose - the dominant biopolymer on earth as it is a natural constituent of all plants -edible and not - is of relevance to the UK market.

“Care was taken to use nano and micro plastic free water for the experiment but no mention was made of steps to reduce environmental nano and microparticles e.g. laboratory staff clothing  and the air – a significant source of microplastics according to Cox et al (DOI: 10.1021/acs.est.9b01517) - a weakness of the protocols used in the authors’ 2023 and 2024 publications

“Both the bag materials themselves and the material captured from this aggressive procedure were analysed for material type and size. The authors also compared the materials to other studies and comment that within the study and between studies there is significant variation in results due to non- harmonised methodologies being used. Harvested materials were shown to be of similar chemical makeup to the parent material but the authors take the same approach to Hernandez et al (2019)³– debunked by Busse et al (2020)[12] - in assuming that all the particles are micro and nano-plastics. This shows the extreme challenge in the analysis and study in the emerging area of micro and nano particles. Hence, great caution is needed in interpreting these results.”

Dr Tim Bond adds: “The authors state that they are using methods that mimic home tea preparation method (which they don’t) to harvest a micro and nano plastic fraction (authors call this MNPL) relevant to real life conditions. They then proceeded to investigate the interactions with living cell lines chosen as models for the gut lining i.e. applying MNPL directly to  the cells. To undertake this, the solid MNPL fraction is sonicated to disperse. Sonication is itself an aggressive technique that not only disperses particles but can break them down further – which the authors data on particle size distribution shows. This further material modification is applied to cells at a concentration which the authors themselves state is ‘not designed to be physiologically relevant’ but at a known subtoxic level. The level chosen was from double to 5x the concentration of MNPL material  to cells with a contact time of 48-72 hours. This is obviously a very concentrated level and a long exposure time (when the passage of food through the entire human digestive system is in the order of 72 hours) that was needed to be able to measure the outcome with the confocal microscope selected for the study.

“This obviously leads to questions on the appropriateness of this approach and the relevance of the results to real life situations. The experiment completely overwhelmed the cells studies to the point that 100% of the cells were found to have interacted with the applied materials in the 2023 study on which this 2024 study was based. The authors also state from their previous publication – on which methods were based for this paper - that ‘no cytotoxicity, reactive oxygen species induction or integrity loss - - were detected’ even under these highly concentrated conditions.

“An interesting finding in this study was that cellulose MNPL had bio-interactions with the chosen cell lines as did the Nylon and Polypropylene MNPL. This might suggest that these interactions occur with all-natural plant-based foods if the food consumed and digested is broken down to small enough fragments as part of our natural diet.

 “The study of micro and nanoplastics in the environment and their interactions with biological systems, while important, is emerging science. It is imperative with the proliferation of different studies and techniques, with different sensitivities and known and unknown drawbacks, that appropriate harmonised methods are developed and tested between various research groups for robust conclusions to be drawn. The same is true for studying biological interactions where the concentration of materials studied must be relevant to real life exposure levels and situations.”

Dr Tim Bond continues: “The 2019 study authors stated that ‘some manufacturers have shifted to using plastic teabags instead of the traditional paper teabags.’ The 2024 study and the 2025 review do nothing to update this thinking which does not reflect the true situation; tea bag manufacturers have in fact gone the other way and as referenced in the fact box (page 3) have developed fully biodegradable options with alternative plant-based materials. With this in mind the study by Hernandez et al (2019) does not reflect what is typically on sale in the UK and the data is not only very misleading when detailed in UK media aimed at UK consumers, it should, as a result, be ignored as it is bad science.

Dr Tim Bond concludes: “More work, using the very best and the most robust study designs, is needed to fully assess if there are any impacts of micro and nano-plastic particles, but studies have to be vigorously designed with transparency of data on which the authors base their conclusions.

“Consumers should continue to enjoy the many wellness varieties of tea and herbal infusions for their health-promoting benefits, as well as their delicious taste, as part of a healthy balanced diet.”

The Tea Advisory Panel: The Tea Advisory Panel is supported by an unrestricted educational grant from the UK TEA & INFUSIONS ASSOCIATION, the trade association for the UK tea industry. The Panel has been created to provide media with impartial information regarding the health benefits of tea. Panel members include nutritionists; dieticians and doctors.